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Electro-optic imaging Fourier transform spectrometer
NASA Technical Reports Server (NTRS)
Chao, Tien-Hsin (Inventor); Znod, Hanying (Inventor)
An Electro-Optic Imaging Fourier Transform Spectrometer (EOIFTS) for Hyperspectral Imaging is described. The EOIFTS includes an input polarizer, an output polarizer, and a plurality of birefringent phase elements. The relative orientations of the polarizers and birefringent phase elements can be changed mechanically or via a controller, using ferroelectric liquid crystals, to substantially measure the spectral Fourier components of light propagating through the EIOFTS. When achromatic switches are used as an integral part of the birefringent phase elements, the EIOFTS becomes suitable for broadband applications, with over 1 micron infrared bandwidth.
Electro-optic Imaging Fourier Transform Spectrometer
NASA Technical Reports Server (NTRS)
Chao, Tien-Hsin
JPL is developing an innovative compact, low mass, Electro-Optic Imaging Fourier Transform Spectrometer (E-O IFTS) for hyperspectral imaging applications. The spectral region of this spectrometer will be 1 - 2.5 micron (1000-4000/cm) to allow high-resolution, high-speed hyperspectral imaging applications. One application will be the remote sensing of the measurement of a large number of different atmospheric gases simultaneously in the same airmass. Due to the use of a combination of birefringent phase retarders and multiple achromatic phase switches to achieve phase delay, this spectrometer is capable of hyperspectral measurements similar to that of the conventional Fourier transform spectrometer but without any moving parts. In this paper, the principle of operations, system architecture and recent experimental progress will be presented.
Electro-optic Imaging Fourier Transform Spectrometer
NASA Technical Reports Server (NTRS)
Chao, Tien-Hsin
JPL is developing an innovative compact, low mass, Electro-Optic Imaging Fourier Transform Spectrometer (E-0IFTS) for hyperspectral imaging applications. The spectral region of this spectrometer will be 1 - 2.5 pm (1000 -4000 cm-') to allow high-resolution, high-speed hyperspectral imaging applications [l-51. One application will be theremote sensing of the measurement of a large number of different atmospheric gases simultaneously in the sameairmass. Due to the use of a combination of birefiingent phase retarders and multiple achromatic phase switches toachieve phase delay, this spectrometer is capable of hyperspectral measurements similar to that of the conventionalFourier transform spectrometer but without any moving parts. In this paper, the principle of operations, systemarchitecture and recent experimental progress will be presen.
Electro-Optical Imaging Fourier-Transform Spectrometer
NASA Technical Reports Server (NTRS)
Chao, Tien-Hsin; Zhou, Hanying
An electro-optical (E-O) imaging Fourier-transform spectrometer (IFTS), now under development, is a prototype of improved imaging spectrometers to be used for hyperspectral imaging, especially in the infrared spectral region. Unlike both imaging and non-imaging traditional Fourier-transform spectrometers, the E-O IFTS does not contain any moving parts. Elimination of the moving parts and the associated actuator mechanisms and supporting structures would increase reliability while enabling reductions in size and mass, relative to traditional Fourier-transform spectrometers that offer equivalent capabilities. Elimination of moving parts would also eliminate the vibrations caused by the motions of those parts. Figure 1 schematically depicts a traditional Fourier-transform spectrometer, wherein a critical time delay is varied by translating one the mirrors of a Michelson interferometer. The time-dependent optical output is a periodic representation of the input spectrum. Data characterizing the input spectrum are generated through fast-Fourier-transform (FFT) post-processing of the output in conjunction with the varying time delay.
Testing of electro-optical imaging systems
NASA Astrophysics Data System (ADS)
Chrzanowski, Krzysztof; Barela, Jaroslaw; Firmanty, Krzysztof
Humans cannot objectively judge electro-optical imaging systems looking on an image of typical scenery. Quality of the image can be bad for some people but good for others and therefore objective test methods and advanced equipment are needed to evaluate these imaging systems. Test methods and measuring systems that enable reliable testing and evaluation of modern thermal cameras, color and monochrome TV cameras, LLLTV cameras and image intensifier systems are presented in this paper.
Investigation on probing quadratic electro-optic coefficient of tantalum potassium niobate crystal based on Fourier transform
NASA Astrophysics Data System (ADS)
Gao, Ch. Y.; Yu, H. T.; Wen, J.; Zhao, M.; Shang, J. J.; Li, X. L.
A method for probing quadratic electro-optic(QEO) coefficient of tantalum potassium niobate crystal based on Fourier transform was proposed. We acquired all the independent component of QEO coefficient tensor of crystal, they are h11 = 1.56 ×10-14m2 /V2 , h12 = 1.24 ×10-14m2 /V2 and h44 = 0.160 ×10-14m2 /V2 respectively. With the help of the computer digital image processing technology, this method should have further application prospect in the areas of optical properties parameters measuring to the optical functional materials.
Spaceborne astronomy with electro-optical image sensors
NASA Technical Reports Server (NTRS)
Bradley, W. C.
The Space Telescope, planned for orbiting in the early 1980s, is described, with emphasis on its electro-optical image sensing capability. Relative advantages of image tubes and solid state arrays as image detectors are summarized; image tube technology is well characterized, but preference may be given to a more versatile tandem solid state array consisting of one module with high silicon response covering most of the spectrum, and a second intensified array with ultraviolet sensitivity and low noise readout. The classical 'photoelectron noise limit' calculation is reviewed, and a detailed calculation of sensitivity limits adaptable to analysis of image tube or solid state array detectors is also given. In particular, characteristics of a filter to optimize the signal to noise ratio is determined. Typical sensitivity calculations for an image tube detector show that with an exposure of one orbital night (approximately 2000 seconds), 10% photometry may be done to a low limit of visual magnitude.
Electro-optically modulated polarizing Fourier-transform spectrometer for plasma spectroscopy applications.
Howard, John
A new electro-optically modulated optical solid-state (MOSS) interferometer has been constructed for measurement of quantities related to the low-order spectral moments of line emission from optically thin radiant media such as plasmas. When Doppler broadening is dominant, the spectral moments give the Radon transform of corresponding moments of the velocity distribution function of the radiating species. The instrument, which is based on the principle of the Fourier-transform spectrometer, has high etendue and is rugged and compact. When electro-optical path-length modulation techniques are employed, the spectral information is encoded in the temporal frequency domain at harmonics of the modulation frequency and can be obtained by use of a single photodetector. Specifically, for a plasma in drifting local thermodynamic equilibrium the zeroth moment (brightness) is given by the average signal level, the first moment (shift) by the interferometric phase, and the second moment (linewidth) by the fringe visibility. To illustrate the MOSS performance, I present spectroscopic measurements of the time evolution of the plasma ion temperature and flow velocity for rf-heated discharges in the H-1 heliac, a toroidal plasma magnetic confinement at the Australian National University. PMID:11900436
Remote sensing of stress using electro-optics imaging technique
NASA Astrophysics Data System (ADS)
Chen, Tong; Yuen, Peter; Hong, Kan; Tsitiridis, Aristeidis; Kam, Firmin; Jackman, James; James, David; Richardson, Mark; Oxford, William; Piper, Jonathan; Thomas, Francis; Lightman, Stafford
Emotional or physical stresses induce a surge of adrenaline in the blood stream under the command of the sympathetic nerve system, which, cannot be suppressed by training. The onset of this alleviated level of adrenaline triggers a number of physiological chain reactions in the body, such as dilation of pupil and an increased feed of blood to muscles etc. This paper reports for the first time how Electro-Optics (EO) technologies such as hyperspectral [1,2] and thermal imaging[3] methods can be used for the detection of stress remotely. Preliminary result using hyperspectral imaging technique has shown a positive identification of stress through an elevation of haemoglobin oxygenation saturation level in the facial region, and the effect is seen more prominently for the physical stressor than the emotional one. However, all results presented so far in this work have been interpreted together with the base line information as the reference point, and that really has limited the overall usefulness of the developing technology. The present result has highlighted this drawback and it prompts for the need of a quantitative assessment of the oxygenation saturation and to correlate it directly with the stress level as the top priority of the next stage of research.
Electro-Optical Imaging Microscopy of Dye-Doped Artificial Lipidic Membranes
Hajj, Bassam; De Reguardati, Sophie; Hugonin, Loïc; Le Pioufle, Bruno; Osaki, Toshihisa; Suzuki, Hiroaki; Takeuchi, Shoji; Mojzisova, Halina; Chauvat, Dominique; Zyss, Joseph
Artificial lipidic bilayers are widely used as a model for the lipid matrix in biological cell membranes. We use the Pockels electro-optical effect to investigate the properties of an artificial lipidic membrane doped with nonlinear molecules in the outer layer. We report here what is believed to be the first electro-optical Pockels signal and image from such a membrane. The electro-optical dephasing distribution within the membrane is imaged and the signal is shown to be linear as a function of the applied voltage. A theoretical analysis taking into account the statistical orientation distribution of the inserted dye molecules allows us to estimate the doped membrane nonlinearity. Ongoing extensions of this work to living cell membranes are discussed. PMID:19948120
Enhanced secure strategy for electro-optic chaotic systems with delayed dynamics by using fractional Fourier transformation.
Cheng, Mengfan; Deng, Lei; Li, Hao; Liu, Deming
We propose a scheme whereby a time domain fractional Fourier transform (FRFT) is used to post process the optical chaotic carrier generated by an electro-optic oscillator. The time delay signature of the delay dynamics is successfully masked by the FRFT when some conditions are satisfied. Meanwhile the dimension space of the physical parameters is increased. Pseudo random binary sequence (PRBS) with low bit rate (hundreds of Mbps) is introduced to control the parameters of the FRFT. The chaotic optical carrier, FRFT parameters and the PRBS are covered by each other so that the eavesdropper has to search the whole key space to crack the system. The scheme allows enhancing the security of communication systems based on delay dynamics without modifying the chaotic source. In this way, the design of chaos based communication systems can be implemented in a modular manner. PMID:24663864
Q selection for an electro-optical earth imaging system: theoretical and experimental results.
Cochrane, Andy; Schulz, Kevin; Kendrick, Rick; Bell, Ray
This paper explores practical design considerations for selecting Q for an electro-optical earth imaging system, where Q is defined as (λ FN) / pixel pitch. Analytical methods are used to show that, under imaging conditions with high SNR, increasing Q with fixed aperture cannot lead to degradation of image quality regardless of the angular smear rate of the system. The potential for degradation of image quality under low SNR is bounded by an increase of the detector noise scaling as Q. An imaging test bed is used to collect representative imagery for various Q configurations. The test bed includes real world errors such as image smear and haze. The value of Q is varied by changing the focal length of the imaging system. Imagery is presented over a broad range of parameters. PMID:24104104
Electro-optical and SAR image fusion for improvements on target feature estimation
NASA Astrophysics Data System (ADS)
Lampropoulos, George A.; Li, Yifeng; Secker, Jeff; Sevigny, Leandre; Beaudoin, Andre
In this paper, tradeoff studies on several pixel level fusion algorithms and on their performance evaluation criteria are presented. Electro-optical (EO) and SAR sensors are dissimilar and produce images with very low degrees of correlation. These images are initially registered at subpixel level accuracy. The fusion is performed using the following pixel level fusion algorithms: Principal Component Analysis (PCA), Averaging (Ave), Laplacian Pyramid, Filter Subtract Decimate (FSD), Ratio Pyramid, Contrast Pyramid, Gradient Pyramid, Discrete Wavelet Transform (QWT), Shift Invariant DWT (SIDWT) with Haar, Morphological Pyramid, and the recent image fusion method developed by AUG Signals Ltd. A MATLAB based dedicated image fusion toolbox, that includes several pixel level fusion, restoration and registration algorithms, has been recently developed by AUG Signals. This toolbox is used for the tradeoff studies.
An airborne thematic thermal infrared and electro-optical imaging system
NASA Astrophysics Data System (ADS)
Sun, Xiuhong; Shu, Peter
This paper describes an advanced Airborne Thematic Thermal InfraRed and Electro-Optical Imaging System (ATTIREOIS) and its potential applications. ATTIREOIS sensor payload consists of two sets of advanced Focal Plane Arrays (FPAs) - a broadband Thermal InfraRed Sensor (TIRS) and a four (4) band Multispectral Electro-Optical Sensor (MEOS) to approximate Landsat ETM+ bands 1,2,3,4, and 6, and LDCM bands 2,3,4,5, and 10+11. The airborne TIRS is 3-axis stabilized payload capable of providing 3D photogrammetric images with a 1,850 pixel swathwidth via pushbroom operation. MEOS has a total of 116 million simultaneous sensor counts capable of providing 3 cm spatial resolution multispectral orthophotos for continuous airborne mapping. ATTIREOIS is a complete standalone and easy-to-use portable imaging instrument for light aerial vehicle deployment. Its miniaturized backend data system operates all ATTIREOIS imaging sensor components, an INS/GPS, and an e-Gimbal™ Control Electronic Unit (ECU) with a data throughput of 300 Megabytes/sec. The backend provides advanced onboard processing, performing autonomous raw sensor imagery development, TIRS image track-recovery reconstruction, LWIR/VNIR multi-band co-registration, and photogrammetric image processing. With geometric optics and boresight calibrations, the ATTIREOIS data products are directly georeferenced with an accuracy of approximately one meter. A prototype ATTIREOIS has been configured. Its sample LWIR/EO image data will be presented. Potential applications of ATTIREOIS include: 1) Providing timely and cost-effective, precisely and directly georeferenced surface emissive and solar reflective LWIR/VNIR multispectral images via a private Google Earth Globe to enhance NASA's Earth science research capabilities; and 2) Underflight satellites to support satellite measurement calibration and validation observations.
Improved fusing infrared and electro-optic signals for high-resolution night images
NASA Astrophysics Data System (ADS)
Huang, Xiaopeng; Netravali, Ravi; Man, Hong; Lawrence, Victor
Electro-optic (EO) images exhibit the properties of high resolution and low noise level, while it is a challenge to distinguish objects with infrared (IR), especially for objects with similar temperatures. In earlier work, we proposed a novel framework for IR image enhancement based on the information (e.g., edge) from EO images. Our framework superimposed the detected edges of the EO image with the corresponding transformed IR image. Obviously, this framework resulted in better resolution IR images that help distinguish objects at night. For our IR image system, we used the theoretical point spread function (PSF) proposed by Russell C. Hardie et al., which is composed of the modulation transfer function (MTF) of a uniform detector array and the incoherent optical transfer function (OTF) of diffraction-limited optics. In addition, we designed an inverse filter based on the proposed PSF to transform the IR image. In this paper, blending the detected edge of the EO image with the corresponding transformed IR image and the original IR image is the principal idea for improving the previous framework. This improved framework requires four main steps: (1) inverse filter-based IR image transformation, (2) image edge detection, (3) images registration, and (4) blending of the corresponding images. Simulation results show that blended IR images have better quality over the superimposed images that were generated under the previous framework. Based on the same steps, the simulation result shows a blended IR image of better quality when only the original IR image is available.
Multi-sensor fusion of infrared and electro-optic signals for high resolution night images.
Huang, Xiaopeng; Netravali, Ravi; Man, Hong; Lawrence, Victor
Electro-optic (EO) image sensors exhibit the properties of high resolution and low noise level at daytime, but they do not work in dark environments. Infrared (IR) image sensors exhibit poor resolution and cannot separate objects with similar temperature. Therefore, we propose a novel framework of IR image enhancement based on the information (e.g., edge) from EO images, which improves the resolution of IR images and helps us distinguish objects at night. Our framework superimposing/blending the edges of the EO image onto the corresponding transformed IR image improves their resolution. In this framework, we adopt the theoretical point spread function (PSF) proposed by Hardie et al. for the IR image, which has the modulation transfer function (MTF) of a uniform detector array and the incoherent optical transfer function (OTF) of diffraction-limited optics. In addition, we design an inverse filter for the proposed PSF and use it for the IR image transformation. The framework requires four main steps: (1) inverse filter-based IR image transformation; (2) EO image edge detection; (3) registration; and (4) blending/superimposing of the obtained image pair. Simulation results show both blended and superimposed IR images, and demonstrate that blended IR images have better quality over the superimposed images. Additionally, based on the same steps, simulation result shows a blended IR image of better quality when only the original IR image is available. PMID:23112602
Multi-Sensor Fusion of Infrared and Electro-Optic Signals for High Resolution Night Images
Huang, Xiaopeng; Netravali, Ravi; Man, Hong; Lawrence, Victor
Electro-optic (EO) image sensors exhibit the properties of high resolution and low noise level at daytime, but they do not work in dark environments. Infrared (IR) image sensors exhibit poor resolution and cannot separate objects with similar temperature. Therefore, we propose a novel framework of IR image enhancement based on the information (e.g., edge) from EO images, which improves the resolution of IR images and helps us distinguish objects at night. Our framework superimposing/blending the edges of the EO image onto the corresponding transformed IR image improves their resolution. In this framework, we adopt the theoretical point spread function (PSF) proposed by Hardie et al. for the IR image, which has the modulation transfer function (MTF) of a uniform detector array and the incoherent optical transfer function (OTF) of diffraction-limited optics. In addition, we design an inverse filter for the proposed PSF and use it for the IR image transformation. The framework requires four main steps: (1) inverse filter-based IR image transformation; (2) EO image edge detection; (3) registration; and (4) blending/superimposing of the obtained image pair. Simulation results show both blended and superimposed IR images, and demonstrate that blended IR images have better quality over the superimposed images. Additionally, based on the same steps, simulation result shows a blended IR image of better quality when only the original IR image is available. PMID:23112602
Fusing electro-optic and infrared signals for high resolution night images
NASA Astrophysics Data System (ADS)
Huang, Xiaopeng; Netravali, Ravi; Man, Hong; Lawrence, Victor
Electro-optic (EO) images exhibit the properties of high resolution and low noise level, while it is a challenge to distinguish objects at night through infrared (IR) images, especially for objects with a similar temperature. Therefore, we will propose a novel framework of IR image enhancement based on the information (e.g., edge) from EO images, which will result in high resolution IR images and help us distinguish objects at night. Superimposing the detected edge of the EO image onto the corresponding transformed IR image is our principal idea for the proposed framework. In this framework, we will adopt the theoretical point spread function (PSF) proposed by Russell C. Hardie et al. for our IR image system, which is contributed by the modulation transfer function (MTF) of a uniform detector array and the incoherent optical transfer function (OTF) of diffraction-limited optics. In addition, we will design an inverse filter in terms of the proposed PSF to conduct the IR image transformation. The framework requires four main steps, which are inverse filter-based IR image transformation, EO image edge detection, registration and superimposing of the obtained image pair. Simulation results will show the superimposed IR images.
Performance evaluation of panoramic electro-optic imagers using the TOD method
NASA Astrophysics Data System (ADS)
Désaulniers, Pierre; Thibault, Simon
The triangle orientation discrimination (TOD) method is an emerging technique for the evaluation of electro-optical (EO) systems. In this method, the test pattern is a non-periodic equilateral triangle in one of four different orientations (apex up, down, left, or right), and the measurement procedure is a robust four-alternative forced-choice psychophysical process. This leads to a time-consuming task. Consequently, software models have been developed to replace the required human observers. These models base their decision on the orientation of the target using correlation between observed data and the set of four differently oriented targets. This study investigates for the first time how this method can be applied to highly distorted OE systems like hemispheric imagers. These types of systems have inherent large distortion, but the distortion should not be considered as an aberration but rather the result of the projection of a hemispheric field (3D) on a 2D sensor. The distortion deforms the image of the targets and image processing is usually performed to remove distortion and straighten the field of view. We present a comparison in accuracy and computational burden for the evaluation of EO system performance between cases where tested images are pre-processed and correlated to unchanged triangle targets and where untouched (distorted) images are correlated with position-wise distorted targets. This is a first evaluation of the application of the TOD with the goal of obtaining an image quality criterion for panoramic imagers.
Process for the development of image quality metrics for underwater electro-optic sensors
NASA Astrophysics Data System (ADS)
Taylor, James S., Jr.; Cordes, Brett
Electro-optic identification (EOID) sensors have been demonstrated as an important tool in the identification of bottom sea mines and are transitioning to the fleet. These sensors produce two and three-dimensional images that will be used by operators and algorithms to make the all-important decision regarding use of neutralization systems against sonar contacts classified as mine-like. The quality of EOID images produced can vary dramatically depending on system design, operating parameters, and ocean environment, necessitating the need for a common scale of image quality or interpretability as a basic measure of the information content of the output images and the expected performance that they provide. Two candidate approaches have been identified for the development of an image quality metric. The first approach is the development of a modified National Imagery Interpretability Rating Scale (NIIRS) based on the EOID tasks. Coupled with this new scale would be a modified form of the General Image Quality Equation (GIQE) to provide a bridge from the system parameters to the NIIRS scale. The other approach is based on the Target Acquisition Model (TAM) that has foundations in Johnson"s criteria and a set of tasks. The following paper presents these two approaches along with an explanation of the application to the EOID problem.
Single-shot time-resolved THz spectroscopy using non-collinear electro-optic imaging
NASA Astrophysics Data System (ADS)
Wang, Zhenyou; Su, Fuhai; Hegmann, Frank A.
We demonstrate a technique for rapid substance identification via single-shot, coherent THz imaging using non-collinear electro-optic sampling. A THz probe pulse generated in ZnTe is transmitted through the sample then focused on a (110) ZnTe detection crystal. An 800nm, 100fs optical pulse employed as a sampling beam passes through the ZnTe detection crystal at an angle of 7^o relative to the THz beam.footnotetextT. Yasuda et al., Opt. Commun. 267, 128 (2006) The THz field induced birefringence is resolved as a variation of the intensity of the sampling pulse transmitted through a crossed polarizer. The modified sampling beam spot is imaged using a CCD camera. Because of the non-collinear geometry, the spatial overlap between the THz field and the optical pulse depends on the temporal position within the THz waveform. Consequently, we obtain high-resolution 2D images of the THz waveform without scanning the relative path length. The resolution of the absorption spectra extracted from wet paper and lactose using the single-shot imaging approach is comparable to the resolution obtained through conventional scanning lock-in measurements. Possible applications for substance detection are discussed.
Canopy induced aberration correction in airborne electro-optical imaging systems
NASA Astrophysics Data System (ADS)
Harder, James A.; Sprague, Michaelene W.
An increasing number of electro-optical systems are being used by pilots in tactical aircraft. This means that the afore mentioned systems must operate through the aircrafts canopy, unfortunately the canopy functions as a less than ideal lens element in the electro-optical sensor optical path. The canopy serves first and foremost as an aircraft structural component, considerations like minimizing the drag co-efficient and the ability to survive bird strikes take precedence over achieving optimal optical characteristics. This paper describes how the authors characterized the optical characteristics of an aircraft canopy. Families of modulation transfer functions were generated, for various viewing geometries through the canopy and for various electro-optical system entrance pupil diameters. These functions provided us with the means to significantly reduce the effect of the canopy "lens" on the performance of a representative electro-optical system, using an Astigmatic Corrector Lens. A comparison of the electro-optical system performance with and without correction is also presented.
Terahertz spectroscopic imaging using noncollinear electro-optic sampling and a multistep mirror without shifting the object
NASA Astrophysics Data System (ADS)
Itani, Norihiko; Maruyama, Kazunori; Hasegawa, Shin-ya; Wakana, Shinichi
We previously developed a high-speed terahertz spectroscopic imaging method based on electro-optic sampling with a noncollinear geometry of the THz beam and probe laser beam and using a multistep mirror in the path of the probe beam. We set the incident probe laser into MAST at a 45° angle, to prevent interference between adjacent beams. However, this produced beam vignetting, so imaging had to be performed twice, between sample movements, and this increased the imaging time accordingly. Thus, we improved the probe-laser imaging system after reflecting from the MAST to correct for the effects of diffraction. This prevents interference from adjacent beams and allows the angle of incidence on the MAST to be set to 0°, enabling the entire sample surface to be imaged in one measurement. As a result, we are able to perform measurements in 40 seconds, half the time of the previous method, and obtain a 28x28-pixel spectral image with spatial resolution of 1.07 mm. To verify the imaging performance, we also measured test samples, showing that the shape and thickness of items inside an opaque plastic case can be distinguished using amplitude and phase images, and metallic foreign objects can be detected. We also evaluated the method and were able to show the validity of the spectral imaging results by distinguishing the transmission or blocking of arbitrary frequency components.
Electro-optical testing of fully depleted CCD image sensors for the Large Synoptic Survey Telescope camera
NASA Astrophysics Data System (ADS)
Doherty, Peter E.; Antilogus, Pierre; Astier, Pierre; Chiang, James; Gilmore, D. Kirk; Guyonnet, Augustin; Huang, Dajun; Kelly, Heather; Kotov, Ivan; Kubanek, Petr; Nomerotski, Andrei; O'Connor, Paul; Rasmussen, Andrew; Riot, Vincent J.; Stubbs, Christopher W.; Takacs, Peter; Tyson, J. Anthony; Vetter, Kurt
The LSST Camera science sensor array will incorporate 189 large format Charge Coupled Device (CCD) image sensors. Each CCD will include over 16 million pixels and will be divided into 16 equally sized segments and each segment will be read through a separate output amplifier. The science goals of the project require CCD sensors with state of the art performance in many aspects. The broad survey wavelength coverage requires fully depleted, 100 micrometer thick, high resistivity, bulk silicon as the imager substrate. Image quality requirements place strict limits on the image degradation that may be caused by sensor effects: optical, electronic, and mechanical. In this paper we discuss the design of the prototype sensors, the hardware and software that has been used to perform electro-optic testing of the sensors, and a selection of the results of the testing to date. The architectural features that lead to internal electrostatic fields, the various effects on charge collection and transport that are caused by them, including charge diffusion and redistribution, effects on delivered PSF, and potential impacts on delivered science data quality are addressed.
Imaging Fourier transform spectrometer
Bennett, C.L.
This invention is comprised of an imaging Fourier transform spectrometer having a Fourier transform infrared spectrometer providing a series of images to a focal plane array camera. The focal plane array camera is clocked to a multiple of zero crossing occurrences as caused by a moving mirror of the Fourier transform infrared spectrometer and as detected by a laser detector such that the frame capture rate of the focal plane array camera corresponds to a multiple of the zero crossing rate of the Fourier transform infrared spectrometer. The images are transmitted to a computer for processing such that representations of the images as viewed in the light of an arbitrary spectral ``fingerprint`` pattern can be displayed on a monitor or otherwise stored and manipulated by the computer.
Fourier plane imaging microscopy
Dominguez, Daniel Peralta, Luis Grave de; Alharbi, Nouf; Alhusain, Mdhaoui; Bernussi, Ayrton A.
We show how the image of an unresolved photonic crystal can be reconstructed using a single Fourier plane (FP) image obtained with a second camera that was added to a traditional compound microscope. We discuss how Fourier plane imaging microscopy is an application of a remarkable property of the obtained FP images: they contain more information about the photonic crystals than the images recorded by the camera commonly placed at the real plane of the microscope. We argue that the experimental results support the hypothesis that surface waves, contributing to enhanced resolution abilities, were optically excited in the studied photonic crystals.
Terahertz wavefront assessment based on 2D electro-optic imaging
NASA Astrophysics Data System (ADS)
Cahyadi, Harsono; Ichikawa, Ryuji; Degert, Jérôme; Freysz, Eric; Yasui, Takeshi; Abraham, Emmanuel
Complete characterization of terahertz (THz) radiation becomes an interesting yet challenging study for many years. In visible optical region, the wavefront assessment has been proved as a powerful tool for the beam profiling and characterization, which consequently requires 2-dimension (2D) single-shot acquisition of the beam cross-section to provide the spatial profile in time- and frequency-domain. In THz region, the main problem is the lack of effective THz cameras to satisfy this need. In this communication, we propose a simple setup based on free-space collinear 2D electrooptic sampling in a ZnTe crystal for the characterization of THz wavefronts. In principle, we map the optically converted, time-resolved data of the THz pulse by changing the time delay between the probe pulse and the generated THz pulse. The temporal waveforms from different lens-ZnTe distances can clearly indicate the evolution of THz beam as it is converged, focused, or diverged. From the Fourier transform of the temporal waveforms, we can obtain the spectral profile of a broadband THz wave, which in this case within the 0.1-2 THz range. The spectral profile also provides the frequency dependency of the THz pulse amplitude. The comparison between experimental and theoretical results at certain frequencies (here we choose 0.285 and 1.035 THz) is in a good agreement suggesting that our system is capable of THz wavefront characterization. Furthermore, the implementation of Hartmann/Shack-Hartmann sensor principle enables the reconstruction of THz wavefront. We demonstrate the reconstruction of THz wavefronts which are changed from planar wave to spherical one due to the insertion of convex THz lens in the THz beam path. We apply and compare two different reconstruction methods: linear integration and Zernike polynomial. Roughly we conclude that the Zernike method provide smoother wavefront shape that can be elaborated later into quantitative-qualitative analysis about the wavefront
Real-Time THz Imaging Using Full-Field Electro-Optic Sampling
NASA Astrophysics Data System (ADS)
Ayesheshim, A.; Bushfield, I.; Hegmann, F. A.
Real time terahertz imaging offers diverse opportunities and applications for non-destructive imaging applications [1,2]. In this paper, we demonstrate real-time THz imaging of still, moving, and concealed objects. Using a Ti: sapphire amplifier laser system, a THz beam is generated and detected via optical rectification and EO sampling respectively using [110] ZnTe wafers. Real time THz video rate imaging of metal objects and dripping water within a cardboard cylinder are clearly seen by an 8-bit grayscale CCD camera. The ring-like temporal and spatial intensity distribution of the various frequency components of the THz signal on the focal plane is also studied. To improve SNR, we use frame averaging and dynamic subtraction methods [3]. [4pt] [1] B .B. Hu and M. C. Nuss, Opt.Lett. 20, 1716(1995). [0pt] [2] K.Kawase, Y.Ogawa, Y.Watanabe, Opt. Express 11, 2546(2003). [0pt] [3] Z.Jiang, X.G.Xu, and X. -C. Zhang, Appl.Opt.39, 2982-2987(2000).
Electro-Optical BLM Chips Enabling Dynamic Imaging of Ordered Lipid Domains
Shao, Chenren; Kendall, Eric; DeVoe, Don L.
Studies of lipid rafts, ordered microdomains of sphingolipids and cholesterol within cell membranes, are essential in probing the relationships between membrane organization and cellular function. While in vitro studies of lipid phase separation are commonly performed using spherical vesicles as model membranes, the utility of these models is limited by a number of factors. Here we present a microfluidic device that supports simultaneous electrical measurements and confocal imaging of on-chip bilayer lipid membranes (BLMs), enabling real-time multi-domain imaging of membrane organization. The chips further support closed microfluidic access to both sides of the membrane, allowing the membrane boundary conditions to be rapidly changed and providing a mechanism for dynamically adjusting membrane curvature through application of a transmembrane pressure gradient. Here we demonstrate the platform through the study of dynamic generation and dissolution of ordered lipid domains as membrane components are transported to and from the supporting annulus containing solvated lipids and cholesterol. PMID:22728885
Electro-Optical Characterization
Not Available
In the Electro-Optical Characterization group, within the National Center for Photovoltaic's Measurements and Characterization Division, we use various electrical and optical experimental techniques to relate photovoltaic device performance to the methods and materials used to produce them. The types of information obtained by these techniques range from small-scale atomic-bonding information to large-scale macroscopic quantities such as optical constants and electron-transport properties. Accurate and timely measurement of the electro-optical properties as a function of device processing provides researchers and manufacturers with the knowledge needed to troubleshoot problems and develop the knowledge base necessary for reducing cost, maximizing efficiency, improving reliability, and enhancing manufacturability. We work collaboratively with you to solve materials- and device-related R&D problems. This sheet summarizes our primary techniques and capabilities.
Field-of-view analysis of a polarization interference Fourier transform imaging spectrometer.
DeHoog, Edward; Xia, Xiaowei; Parfenov, Alexander; Shih, Min-Yi
The Fourier transform imaging spectrometer (FTIS) is an important tool for the measurement of spectral information in a scene. Advances in electro-optic crystal systems have led to the advent of the FTIS based on polarization interference filters. The operation of these devices as spectrometers has been well characterized, but the imaging capabilities have yet to be thoroughly explored. We explore the field-of-view limitations that occur when using this particular type of FTIS. PMID:21947057
Triple image encryption scheme in fractional Fourier transform domains
NASA Astrophysics Data System (ADS)
Liu, Zhengjun; Dai, Jingmin; Sun, Xiaogang; Liu, Shutian
We proposed a triple image encryption scheme by use of fractional Fourier transform. In this algorithm, an original image is encoded in amplitude part and other two images are encoded into phase information. The key of encryption algorithm is obtained from the difference between the third image and the output phase of transform. In general case, random phase encoding technology is not required in the proposed algorithm. Moreover, all information of images is preserved in theory when image are decrypted with correct key. The optical implementation of the algorithm is presented with an electro-optical hybrid structure. Numerical simulations have demonstrated the efficiency and the security of this algorithm. Based on this scheme a multiple image algorithm is expanded and designed.
An electro-optical imaging approach to the prompt signal processing problem of mega-channel SSC detector arrays
Lowry, M.; Ables, E.; Bionta, R.; Haigh, R.; Hugenberg, K.; Kalibjian, R.; McConaghy, C.; Milton, D.; Rotter, M.; Schulte, H.
The physics demands of high luminosity at the SSC and the sometimes subtle measurements required to elucidate new physics will undoubtedly tax existing instrumentation. As is the case with most experimental fields, new physics follows from better measurement concepts and technologies. We expect this to be the case with the SSC as well. In what follows, we offer a glimpse of what may be possible using some of the recent results from the emerging technologies in the field of electro-optics. 12 refs., 4 figs.
Hackel, L.A.; Hermann, M.R.; Dane, C.B.; Tiszauer, D.H.
A solid state laser is frequency tripled to 0.3 {micro}m. A small portion of the laser is split off and generates a Stokes seed in a low power oscillator. The low power output passes through a mask with the appropriate hole pattern. Meanwhile, the bulk of the laser output is focused into a larger stimulated Brillouin scattering (SBS) amplifier. The low power beam is directed through the same cell in the opposite direction. The majority of the amplification takes place at the focus which is the fourier transform plane of the mask image. The small holes occupy large area at the focus and thus are preferentially amplified. The amplified output is now imaged onto the multichip module where the holes are drilled. Because of the fourier plane amplifier, only about 1/10th the power of a competitive system is needed. This concept allows less expensive masks to be used in the process and requires much less laser power. 1 fig.
Hackel, Lloyd A.; Hermann, Mark R.; Dane, C. Brent; Tiszauer, Detlev H.
A solid state laser is frequency tripled to 0.3 .mu.m. A small portion of the laser is split off and generates a Stokes seed in a low power oscillator. The low power output passes through a mask with the appropriate hole pattern. Meanwhile, the bulk of the laser output is focused into a larger stimulated Brillouin scattering (SBS) amplifier. The low power beam is directed through the same cell in the opposite direction. The majority of the amplification takes place at the focus which is the fourier transform plane of the mask image. The small holes occupy large area at the focus and thus are preferentially amplified. The amplified output is now imaged onto the multichip module where the holes are drilled. Because of the fourier plane amplifier, only .about.1/10th the power of a competitive system is needed. This concept allows less expensive masks to be used in the process and requires much less laser power.
Imaging Fourier Transform Spectrometer
Bennett, C.L.; Carter, M.R.; Fields, D.J.; Hernandez, J.
The operating principles of an Imaging Fourier Transform Spectrometer (IFTS) are discussed. The advantages and disadvantages of such instruments with respect to alternative imaging spectrometers are discussed. The primary advantages of the IFTS are the capacity to acquire more than an order of magnitude more spectral channels than alternative systems with more than an order of magnitude greater etendue than for alternative systems. The primary disadvantage of IFTS, or FTS in general, is the sensitivity to temporal fluctuations, either random or periodic. Data from the IRIFTS (ir IFTS) prototype instrument, sensitive in the infrared, are presented having a spectral sensitivity of 0.01 absorbance units, a spectral resolution of 6 cm{sup {minus}1} over the range 0 to 7899 cm{sup {minus}1}, and a spatial resolution of 2.5 mr.
Tsang, Mankei
The quantum dynamics of the coupling between a cavity optical field and a resonator microwave field via the electro-optic effect is studied. This coupling has the same form as the optomechanical coupling via radiation pressure, so all previously considered optomechanical effects can in principle be observed in electro-optic systems as well. In particular, I point out the possibilities of laser cooling of the microwave mode, entanglement between the optical mode and the microwave mode via electro-optic parametric amplification, and back-action-evading optical measurements of a microwave quadrature.
Organic electro-optic materials
NASA Astrophysics Data System (ADS)
Dalton, Larry R.; Robinson, Bruce H.; Jen, Alex K.; Ried, Philip; Eichinger, Bruce; Jang, Sei-Hum; Luo, Jingdong; Liu, Sen; Liao, Yi; Firestone, Kimberly A.; Bhatambrekar, Nishant P.; Bale, Denise; Haller, Marnie A.; Bhattacharjee, Sanchali; Schendel, Jessica; Sullivan, Philip A.; Hammond, Scott; Buker, Nicholas; Cady, Field; Chen, Antao; Steier, William H.
The potential of organic electro-optic materials for large electro-optic activity and fast response to applied electric fields (leading to 100 GHz device bandwidths) is important and increasingly well-recognized. In this communication, we demonstrate how quantum and statistical mechanical calculations can be used to guide the systematic improvement of both molecular first hyperpolarizability (β) and macroscopic electro-optic activity (r). Femtosecond time-resolved, wavelength-agile Hyper-Rayleigh Scattering (HRS) measurements have been used to measure β values relative to chloroform and to avoid confusion associated with two photon contributions. Electro-optic coefficients have been characterized by simple reflection (Teng-Man method), attenuated total reflection (ATR), and Mach Zehnder interferometry. "Constant bias" modifications of these techniques have been used to permit investigation of optimized poling conditions. Organic electro-optic materials also afford unique advantages for the fabrication of conformal and flexible devices, for the integration of disparate materials, and for exploitation of novel manufacturing technologies such as soft lithography. Both stripline and ring microresonator structures have been fabricated by soft lithography. The integration of organic electro-optic materials with silicon photonics (both split ring microresonators and photonic bandgap circuitry) has been demonstrated.
Electro-optical Synergy Technique
El-Domyati, Moetaz; El-Ammawi, Tarek S.; Medhat, Walid; Moawad, Osama; Mahoney, My G.
Objectives: Electro-optical synergy technology is one of the most recently described methods for nonablative skin rejuvenation. The aim of this study is to evaluate the effects of electro-optical synergy on connective tissue composition by histological and immunohistochemical techniques coupled with computerized morphometric analysis. Design: A prospective clinical study. Participants: Six volunteers with Fitzpatrick skin types 3 to 4 and Glogau class I to II wrinkles were subjected to three months (6 sessions at 2-week intervals) of electro-optical synergy treatment. Measurements: Standard photographs and skin biopsies were obtained at baseline as well as three and six months after the start of treatment. The authors performed quantitative evaluation of total elastin, tropoelastin, collagen types I, III, and VII, and newly synthesized collagen. Results: Noticeable clinical and histological improvement was observed after electro-optical synergy treatment. A statistically significant increase in the means of collagen types I, III, and VII, as well as newly synthesized collagen, together with increased levels of tropoelastin, were detected, while the mean level of total elastin was significantly decreased at the end of treatment and three months post-treatment. Conclusion: Electro-optical synergy is an effective treatment for contouring facial skin laxity. This modality stimulates the repair processes and reverses the clinical, as well as the histopathological, signs of aging with the advantage of being a relatively risk-free procedure with minimal patient recovery time. PMID:21203352
Empirical electro-optical and x-ray performance evaluation of CMOS active pixels sensor for low dose, high resolution x-ray medical imaging.
Arvanitis, C D; Bohndiek, S E; Royle, G; Blue, A; Liang, H X; Clark, A; Prydderch, M; Turchetta, R; Speller, R
Monolithic complementary metal oxide semiconductor (CMOS) active pixel sensors with high performance have gained attention in the last few years in many scientific and space applications. In order to evaluate the increasing capabilities of this technology, in particular where low dose high resolution x-ray medical imaging is required, critical electro-optical and physical x-ray performance evaluation was determined. The electro-optical performance includes read noise, full well capacity, interacting quantum efficiency, and pixels cross talk. The x-ray performance, including x-ray sensitivity, modulation transfer function, noise power spectrum, and detection quantum efficiency, has been evaluated in the mammographic energy range. The sensor is a 525 x 525 standard three transistor CMOS active pixel sensor array with more than 75% fill factor and 25 x 25 microm pixel pitch. Reading at 10 f/s, it is found that the sensor has 114 electrons total additive noise, 10(5) electrons full well capacity with shot noise limited operation, and 34% interacting quantum efficiency at 530 nm. Two different structured CsI:Tl phosphors with thickness 95 and 115 microm, respectively, have been optically coupled via a fiber optic plate to the array resulting in two different system configurations. The sensitivity of the two different system configurations was 43 and 47 electrons per x-ray incident on the sensor. The MTF at 10% of the two different system configurations was 9.5 and 9 cycles/mm with detective quantum efficiency of 0.45 and 0.48, respectively, close to zero frequency at approximately 0.44 microC/kg (1.72 mR) detector entrance exposure. The detector was quantum limited at low spatial frequencies and its performance was comparable with high resolution a: Si and charge coupled device based x-ray imagers. The detector also demonstrates almost an order of magnitude lower noise than active matrix flat panel imagers. The results suggest that CMOS active pixel sensors when coupled
Empirical electro-optical and x-ray performance evaluation of CMOS active pixels sensor for low dose, high resolution x-ray medical imaging
Arvanitis, C. D.; Bohndiek, S. E.; Royle, G.; Blue, A.; Liang, H. X.; Clark, A.; Prydderch, M.; Turchetta, R.; Speller, R.
Monolithic complementary metal oxide semiconductor (CMOS) active pixel sensors with high performance have gained attention in the last few years in many scientific and space applications. In order to evaluate the increasing capabilities of this technology, in particular where low dose high resolution x-ray medical imaging is required, critical electro-optical and physical x-ray performance evaluation was determined. The electro-optical performance includes read noise, full well capacity, interacting quantum efficiency, and pixels cross talk. The x-ray performance, including x-ray sensitivity, modulation transfer function, noise power spectrum, and detection quantum efficiency, has been evaluated in the mammographic energy range. The sensor is a 525x525 standard three transistor CMOS active pixel sensor array with more than 75% fill factor and 25x25 {mu}m pixel pitch. Reading at 10 f/s, it is found that the sensor has 114 electrons total additive noise, 10{sup 5} electrons full well capacity with shot noise limited operation, and 34% interacting quantum efficiency at 530 nm. Two different structured CsI:Tl phosphors with thickness 95 and 115 {mu}m, respectively, have been optically coupled via a fiber optic plate to the array resulting in two different system configurations. The sensitivity of the two different system configurations was 43 and 47 electrons per x-ray incident on the sensor. The MTF at 10% of the two different system configurations was 9.5 and 9 cycles/mm with detective quantum efficiency of 0.45 and 0.48, respectively, close to zero frequency at {approx}0.44 {mu}C/kg (1.72 mR) detector entrance exposure. The detector was quantum limited at low spatial frequencies and its performance was comparable with high resolution a:Si and charge coupled device based x-ray imagers. The detector also demonstrates almost an order of magnitude lower noise than active matrix flat panel imagers. The results suggest that CMOS active pixel sensors when coupled to
NASA Astrophysics Data System (ADS)
Yagi, Shogo; Fujiura, Kazuo
We have grown KTN crystals with optical quality, and developed high-speed beam deflectors and variable focal length lenses based on KTN's large electro-optic effect. Furthermore, by using the KTN beam deflectors, we have developed a swept light source for OCT operable at 200 kHz.
A methodology for estimating lateral range curves for electro-optical visible and infrared imaging systems for maritime search and detection applications
NASA Astrophysics Data System (ADS)
DeWeert, Michael J.; Leonard, Carrie L.; Stalder, Carrie L.; Iokepa, Judy; Gradie, Jonathan
Electro-optical (EO) systems with digital image processing and computer-aided detection are increasingly coming into use for maritime surveillance, reconnaissance and search and rescue. EO systems have the potential to improve the consistency of detection, reduce operator workload and fatigue, and improve search efficiency. However, quantifying their performance versus more traditional approaches is problematic, because of the differences in how performance is specified for traditional systems versus modern computer-aided designs. In maritime search applications, system performance is commonly specified in terms of the lateral range curve (LRC). The LRC is a plot of the probability of detection versus horizontal range from the search platform. This metric has a long history, rooted in visual searches by trained human observers. However, it is specified without reference to any false-alarm rate or probability of false alarm. Computer-aided EO performance, on the other hand, is usually specified in terms of Signal-to-Noise Ratio (SNR), Receiver Operating Characteristic (ROC) curve, or some equivalent metric. In this paper, we demonstrate a methodology for estimating LRCs from SNRs or ROC curves. This methodology provides a consistent, quantifiable means for comparing the performance of new and legacy systems.
Shuttle sortie electro-optical instruments study
NASA Technical Reports Server (NTRS)
A study to determine the feasibility of adapting existing electro-optical instruments (designed and sucessfully used for ground operations) for use on a shuttle sortie flight and to perform satisfactorily in the space environment is considered. The suitability of these two instruments (a custom made image intensifier camera system and an off-the-shelf secondary electron conduction television camera) to support a barium ion cloud experiment was studied for two different modes of spacelab operation - within the pressurized module and on the pallet.
Electro-optic network analyzer
NASA Technical Reports Server (NTRS)
Jackson, Todd A.
The bandwidth of frequency domain measurement methods of electrical signals has usually been far greater than the bandwidth of time domain methods. The primary limits of the time domain approach have been the 20 to 30 GHz bandwidth limit for electronic waveform acquisition instrumentation, and the lack of usable electrical pulse generators for excitation of a test device. The bandwidth of frequency domain network analysis appears to have reached a plateau of between 100 to 200 GHz, while time domain measurement have improved markedly in both bandwidth and sensitivity with the introduction of the pulsed laser based electro-optic sampling approach. Network analysis or the measurement of device scattering parameters provides information necessary to the design of electronic network such as high frequency amplifiers, mixers, and phase shifter. The bandwidth of frequency domain network analysis is currently being exceeded by the next generations of high frequency transistors and devices. Thus the electro-optic approach is a natural means of extending network analysis into the range above 100 GHz by employing time domain methods. In this approach, a suitable electrical excitation pulse is generated and propagated along a transmission line toward a test device. In the picosecond domain, laser driven photoconductive switches provide a unique method of generating electrical transients. Several materials were studied for generating short electrical pulses using photoconductive switches. The various semiconductive materials tested for photoconductive switching, and the electro-optic measurement technique used to characterize the material performance are described.
Advanced electro-optical imaging techniques. [conference papers on sensor technology applicable to Large Space Telescope program
NASA Technical Reports Server (NTRS)
Sobieski, S. (Editor); Wampler, E. J. (Editor)
The papers presented at the symposium are given which deal with the present state of sensors, as may be applicable to the Large Space Telescope (LST) program. Several aspects of sensors are covered including a discussion of the properties of photocathodes and the operational imaging camera tubes.
Electro-optical imaging of F-actin and endoplasmic reticulum in living and fixed plant cells.
Allen, N S; Bennett, M N
Confocal and video micrographs of living and fixed alfalfa roots, onion epithelial and pear pollen cells illustrate the architecture of the cytoskeleton and endoplasmic reticulum in plant cells. Fixation of plant tissues to preserve cytoplasmic structure poses special problems. When possible, emphasis should be placed on the imaging of structures in stained living cells over time. The early events that occur when Nod factors or bacteria elicit nodule formation in alfalfa roots will illustrate several approaches to plant cell fixation, staining and imaging. The first observable events after Nod factor stimulation occur in root hairs and are changes in rates of cytoplasmic streaming, nuclear movements, and changes in the shape of the vacuole. Within ten minutes, the endoplasmic reticulum shifts position towards the tip of the root hair. For comparison, the endoplasmic reticulum localization in pollen tubes and onion epithelial cells will be illustrated. The actin cytoskeleton undergoes a series of changes over a twelve hour period. These changes in the cytoskeleton are spatially and temporally correlated with the observed growth changes of the root hairs. This dynamic change of the actin filament and endoplasmic reticulum and associated secretory vesicles in these root hairs suggests a mechanism for the observed root hair growth changes. PMID:9601538
Advanced Electro-Optic Surety Devices
Watterson, C.E.
The Advanced Electro-Optic Surety Devices project was initiated in march 1991 to support design laboratory guidance on electro-optic device packaging and evaluation. Sandia National Laboratory requested AlliedSignal Inc., Kansas City Division (KCD), to prepare for future packaging efforts in electro-optic integrated circuits. Los Alamos National Laboratory requested the evaluation of electro-optic waveguide devices for nuclear surety applications. New packaging techniques involving multiple fiber optic alignment and attachment, binary lens array development, silicon V-groove etching, and flip chip bonding were requested. Hermetic sealing of the electro-optic hybrid and submicron alignment of optical components present new challenges to be resolved. A 10-channel electro-optic modulator and laser amplifier were evaluated for potential surety applications.
Airborne Electro-Optical Sensor Simulation System. Final Report.
ERIC Educational Resources Information Center
Hayworth, Don
The total system capability, including all the special purpose and general purpose hardware comprising the Airborne Electro-Optical Sensor Simulation (AEOSS) System, is described. The functional relationship between hardware portions is described together with interface to the software portion of the computer image generation. Supporting rationale…
Using a piezoelectric fiber stretcher to remove the depth ambiguity in optical Fourier domain imaging
NASA Astrophysics Data System (ADS)
Vergnole, Sébastien; Lamouche, Guy; Dufour, Marc; Gauthier, Bruno
This paper reports the study of an Optical Fourier Domain Imaging (OFDI) setup for optical coherence tomography. One of the main drawbacks of OFDI is its inability to differentiate positive and negative depths. Some setups have already been proposed to remove this depth ambiguity by introducing a modulation by means of electro-optic or acousto-optic modulators. In our setup, we implement a piezoelectric fiber stretcher to generate a periodic phase shift between successive A-scans, thus introducing a transverse modulation. The depth ambiguity is then resolved by performing a Fourier treatment in the transverse direction before processing the data in the axial direction. It is similar to the B-M mode scanning already proposed for Spectral-Domain OCT1 but with a more efficient experimental setup. We discuss the advantages and the drawbacks of our technique compared to the technique based on acousto-optics modulators by comparing images of an onion obtained with both techniques.
Iterative electro-optic matrix processor
NASA Astrophysics Data System (ADS)
Carlotto, M. J.
An electro-optic vector matrix processor with electronic feedback is described. The iterative optical processor (IOP) is designed for the rapid solution of linear algebraic equations. The IOP and the iterative algorithm it realizes are analyzed and simulated. A version of the system was fabricated using advanced solid state light sources and detectors plus fiber optic technology, and its performance is evaluated. An extension of the system using wavelength multiplexing is developed and the basic system concepts demonstrated. Its use in the restoration of degraded images or signals (deconvolution) and the computation of matrix eigenvectors and eigenvalues and matrix inversion are demonstrated. The two major case studies pursued are: adaptive phased array radar processing and optimal control. In the former case, the system is used to compute the adaptive antenna weights for a radar system. In the latter case, the IOP solves the linear quadratic regular and algebraic Ricatti equations of modern control theory.
Electro-optic Lightning Detector
NASA Technical Reports Server (NTRS)
Koshak, William J.; Solakiewicz, Richard J.
The design, alignment, calibration, and field deployment of a solid-state lightning detector is described. The primary sensing component of the detector is a potassium dihydrogen phosphate (KDP) electro-optic crystal that is attached in series to a flat plate aluminum antenna; the antenna is exposed to the ambient thundercloud electric field. A semiconductor laser diode (lambda = 685 nm), polarizing optics, and the crystal are arranged in a Pockels cell configuration. Lightning-caused electric field changes are related to small changes in the transmission of laser light through the optical cell. Several hundred lightning electric field change excursions were recorded during five thunderstorms that occurred in the summer of 1998 at the NASA Marshall Space Flight Center (MSFC) in northern Alabama.
Electro-optic modulator material
Adams, John J.; Ebbers, Chris A.
An electro-optic device for use with a laser beam. A crystal has a first face and a second face. Means are provided for applying a voltage across the crystal to obtain a net phase retardation on the polarization of the laser beam when the laser beam is passed through the crystal. In one embodiment the crystal is composed of a compound having the chemical formula ReAe40(BO3)3 where: RE consists of one or more of the following elements La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu and two other elements Y and Sc; and where Ae is from the list of Ca, Sr, or Ba.
Electro-Optic Lighting Detector
NASA Technical Reports Server (NTRS)
Koshak, William J.; Solakiewicz, Richard J.
The design, alignment, calibration, and field deployment of a solid-state lightning detector is described. The primary sensing component of the detector is a potassium dihydrogen phosphate electro-optic crystal that is attached in series to a flat-plate aluminum antenna; the antenna is exposed to the ambient thundercloud electric field. A semiconductor laser diode (lambda = 685 nm), polarizing optics, and the crystal are arranged in a Pockels cell configuration. Lightning-caused electric field changes are related to small changes in the transmission of laser light through the optical cell. Several hundred lightning electric field change excursions were recorded during five thunderstorms that occurred in the summer of 1998 at the NASA Marshall Space Flight Center in northern Alabama.
Electro-optic lightning detector.
Koshak, W J; Solakiewicz, R J
The design, alignment, calibration, and field deployment of a solid-state lightning detector is described. The primary sensing component of the detector is a potassium dihydrogen phosphate electro-optic crystal that is attached in series to a flat-plate aluminum antenna; the antenna is exposed to the ambient thundercloud electric field. A semiconductor laser diode (lambda = 685 nm), polarizing optics, and the crystal are arranged in a Pockels cell configuration. Lightning-caused electric field changes are related to small changes in the transmission of laser light through the optical cell. Several hundred lightning electric field change excursions were recorded during five thunderstorms that occurred in the summer of 1998 at the NASA Marshall Space Flight Center in northern Alabama. PMID:18323949
Bulk Electro-Optical Polymer Component
NASA Technical Reports Server (NTRS)
Gottsche, Allan; Perry, Joseph W.; Perry, Kelly J.
Polymer serves in high-voltage sensors and laser-beam modulators. Electro-optical polymer of relatively low cost formed as bulk specimen from azo dye 4-(4-nitrophenylazo)-N-ethyl, N-2-hydroxyethylaniline, also known as Disperse Red 1 or DR1, and transparent epoxy. More stable than prior electro-optical polymers based on DR1 and poly(methylmethacrylate). If polymer were sandwiched between electrodes, it provides direct measurement of high voltage via electro-optical effect. Has significant nonlinear optical properties. Material useful in microelectronics, micro-optics, integrated optics, and testing of materials. Polymer withstands electric fields up to 120 kV/cm.
Electro-Optic Lightning Detector
NASA Technical Reports Server (NTRS)
Koshak, William J.; Solakiewica, R. J.
Electric field measurements are fundamental to the study of thunderstorm electrification, thundercloud charge structure, and the determination of the locations and magnitudes of charges deposited by lightning. Continuous field observations can also be used to warn of impending electrical hazards. For example, the USAF Eastern Range (ER) and NASA Kennedy Space Center (KSC) in Florida currently operate a ground-based network of electric field mill sensors to warn against lightning hazards to space vehicle operations/launches. The sensors provide continuous recordings of the ambient field. Others investigators have employed flat-plate electric field antennas to detect changes In the ambient field due to lightning. In each approach, electronic circuitry is used to directly detect and amplify the effects of the ambient field on an exposed metal conductor (antenna plate); in the case of continuous field recordings, the antenna plate is alternately shielded and unshielded by a grounded conductor. In this work effort, an alternate optical method for detecting lightning-caused electric field changes is Introduced. The primary component in the detector is an anisotropic electro-optic crystal of potassium di-hydrogen phosphate (chemically written as KH2PO4 (KDP)). When a voltage Is placed across the electro-optic crystal, the refractive Indices of the crystal change. This change alters the polarization state of a laser light beam that is passed down the crystal optic axis. With suitable application of vertical and horizontal polarizers, a light transmission measurement is related to the applied crystal voltage (which in turn Is related to the lightning caused electric field change). During the past two years, all critical optical components were procured, assembled, and aligned. An optical housing, calibration set-up, and data acquisition system was integrated for breadboard testing. The sensor was deployed at NASA Marshall Space Flight Center (MSFC) in the summer of 1998 to
Electro-optical field sensor using single total internal reflection in electro-optical crystals
NASA Astrophysics Data System (ADS)
Kijima, K.; Abe, O.; Shimizu, A.; Nakamura, T.; Kono, H.; Hagihara, S.; Torikai, E.; Hori, H.
A novel electro-optical radio frequency field sensor with simple structure and high sensitivity is realized using single total internal reflection in electro-optical crystals. Without employing any waveguide structures, the minimum detectable electric field strength of the total internal reflection electro-optical-sensor is estimated to 86.52 dB μV/m (21.18 mV/m) at a resolution band width of 100 Hz for a short interaction length.
NASA Technical Reports Server (NTRS)
Zou, Yingyin (Inventor); Chen, Qiushui (Inventor); Zhang, Run (Inventor); Jiang, Hua (Inventor)
An electro-optic Q-switch for generating sequence of laser pulses was disclosed. The Q-switch comprises a quadratic electro-optic material and is connected with an electronic unit generating a radio frequency wave with positive and negative pulses alternatively. The Q-switch is controlled by the radio frequency wave in such a way that laser pulse is generated when the radio frequency wave changes its polarity.
Electro-optic component mounting device
Gruchalla, Michael E.
A technique is provided for integrally mounting a device such as an electro-optic device (50) in a transmission line to avoid series resonant effects. A center conductor (52) of the transmission line has an aperture (58) formed therein for receiving the device (50). The aperture (58) splits the center conductor into two parallel sections on opposite sides of the device. For a waveguide application, the center conductor is surrounded by a conductive ground surface (54), which is spaced apart from the center conductor with a dielectric material (56). One set of electrodes formed on the surface of the electro-optic device (50) is directly connected to the center conductor 52 and an electrode formed on the surface of the electro-optic device is directly connected to the conductive ground surface (54). The electrodes formed on the surface of the electro-optic device are formed on curved sections of the surface of the device to mate with correspondingly shaped electrodes on the conductor and ground surface to provide a uniform electric field across the electro-optic device. The center conductor includes a passage ( 60) formed therein for passage of optical signals to an electro-optic device.
Electro-optic component mounting device
Gruchalla, M.E.
A technique is provided for integrally mounting a device such as an electro-optic device in a transmission line to avoid series resonant effects. A center conductor of the transmission line has an aperture formed therein for receiving the device. The aperture splits the center conductor into two parallel sections on opposite sides of the device. For a waveguide application, the center conductor is surrounded by a conductive ground surface which is spaced apart from the center conductor with a dielectric material. One set of electrodes formed on the surface of the electro-optic device is directly connected to the center conductor and an electrode formed on the surface of the electro-optic device is directly connected to the conductive ground surface. The electrodes formed on the surface of the electro-optic device are formed on curved sections of the surface of the device to mate with correspondingly shaped electrodes on the conductor and ground surface to provide a uniform electric field across the electro-optic device. The center conductor includes a passage formed therein for passage of optical signals to an electro-optic device. 10 figs.
Integrated Electro-optical Laser-Beam Scanners
NASA Technical Reports Server (NTRS)
Boord, Warren T.
Scanners using solid-state devices compact, consume little power, and have no moving parts. Integrated electro-optical laser scanner, in conjunction with external lens, points outgoing beam of light in any number of different directions, depending on number of upper electrodes. Offers beam-deflection angles larger than those of acousto-optic scanners. Proposed for such diverse applications as nonimpact laser printing, color imaging, ranging, barcode reading, and robotic vision.
Laboratory for testing electro-optical surveillance systems
NASA Astrophysics Data System (ADS)
Chrzanowski, K.
A modern laboratory capable to carry out expanded tests of all types of electro-optical surveillance systems (thermal imagers, TV/LLLTV cameras, night vision devices, laser range finders/designators/illuminators, multi-sensor surveillance systems) and basic modules of such surveillance systems (IR FPA/CCD/CMOS/EBAPS sensors, image intensifier tubes, optical objectives) was developed and is presented in this paper. The laboratory can be treated as a both scientific and technical achievement due to its several features. First, all important parameters of modern electro-optical surveillance systems or parameters of basic modules of such systems can be measured. Second, the laboratory is built using a set of semi-independent modular test stations. This modular concept enables easy creations of many versions optimized for different applications. Third, interpretation of the measurement data is supported by a set of specialized computer simulation programs. Fourth, all tests stations in the laboratory were developed by the same design team and are based on similar test concepts.. Because of these features the laboratory of electro-optical surveillance technology presented in this paper can be an optimal solutions for scientific centers or industrial companies who plan to enter and make quick progress in all main areas of surveillance technology.
Rotational-translational fourier imaging system
NASA Technical Reports Server (NTRS)
Campbell, Jonathan W. (Inventor)
This invention has the ability to create Fourier-based images with only two grid pairs. The two grid pairs are manipulated in a manner that allows (1) a first grid pair to provide multiple real components of the Fourier-based image and (2) a second grid pair to provide multiple imaginary components of the Fourier-based image. The novelty of this invention resides in the use of only two grid pairs to provide the same imaging information that has been traditionally collected with multiple grid pairs.
A large aperture electro-optic deflector
NASA Astrophysics Data System (ADS)
Bosco, A.; Boogert, S. T.; Boorman, G. E.; Blair, G. A.
An electro-optic laser beam deflector with a clear optical aperture of 8.6 mm has been designed, realized, and tested. The electro-optic material used to implement the device was a MgO:LiNbO3 crystal. The exceptionally large aperture makes the device suitable for applications where fast scanning of high power laser beams is needed. The measured deflection angle was 120 μrad/kV for a total length of electro-optic material of 90 mm. A mode quality analysis of the laser beam revealed that the M2 of the laser is affected by less than 4% during scan operation when maximum driving voltage is applied.
Electro-Optical Characterization at NREL
Keyes, B. M.; Dippo, P.; Gedvilas, L.; Johnston, S.; Levi, D.; Metzger, W.; Sopori, B.
One of the core issues in all of the photovoltaics technologies is relating PV device performance to the methods and materials used to produce them. Due to the nature of PV devices, the electronic and optical properties of the materials are key to device performance. The relationship between materials growth and processing, the resulting electro-optical properties, and device performance can be extremely complex and difficult to determine without direct measurement of these properties. Accurate and timely measurement of the electro-optical properties as a function of device processing provides researchers and manufacturers with the knowledge they need to troubleshoot problems and develop the knowledge base necessary for reducing cost, maximizing efficiency, improving reliability, and enhancing manufacturability. The Electro-optical Characterization Team at NREL provides this support for all internal and external projects funded by the PV Program.
Polarization Independent Electro-Optic Modulator
NASA Technical Reports Server (NTRS)
Yao, Xiao-Tian Steve (Inventor)
A polarization insensitive electro-optic modulator is constructed by providing a polarization beamsplitter to separate an incoming light beam into two orthogonally plane polarized beams. Each of the polarized beams passes through a separate electro-optic modulator where each beam is modulated by the same data signal. After modulation the beams are combined to yield a modulated beam having modulated components that are orthogonally polarized. Not only is this device insensitive to changes in polarization of the input beam, the final modulated beam can be detected by optical receivers without regard to polarization alignment of the modulated beam and the receiver.
Electro-optic voltage sensor head
Crawford, Thomas M.; Davidson, James R.; Woods, Gregory K.
The invention is an electro-optic voltage sensor head designed for integration with existing types of high voltage transmission and distribution apparatus. The sensor head contains a transducer, which comprises a transducing material in which the Pockels electro-optic effect is observed. In the practice of the invention at least one beam of electromagnetic radiation is routed into the transducing material of the transducer in the sensor head. The beam undergoes an electro-optic effect in the sensor head when the transducing material is subjected to an E-field. The electro-optic effect is observed as a differential phase a shift, also called differential phase modulation, of the beam components in orthogonal planes of the electromagnetic radiation. In the preferred embodiment the beam is routed through the transducer along an initial axis and then reflected by a retro-reflector back substantially parallel to the initial axis, making a double pass through the transducer for increased measurement sensitivity. The preferred embodiment of the sensor head also includes a polarization state rotator and at least one beam splitter for orienting the beam along major and minor axes and for splitting the beam components into two signals which are independent converse amplitude-modulated signals carrying E-field magnitude and hence voltage information from the sensor head by way of optic fibers.
Electro-optic voltage sensor head
Crawford, T.M.; Davidson, J.R.; Woods, G.K.
The invention is an electro-optic voltage sensor head designed for integration with existing types of high voltage transmission and distribution apparatus. The sensor head contains a transducer, which comprises a transducing material in which the Pockels electro-optic effect is observed. In the practice of the invention at least one beam of electromagnetic radiation is routed into the transducing material of the transducer in the sensor head. The beam undergoes an electro-optic effect in the sensor head when the transducing material is subjected to an E-field. The electro-optic effect is observed as a differential phase a shift, also called differential phase modulation, of the beam components in orthogonal planes of the electromagnetic radiation. In the preferred embodiment the beam is routed through the transducer along an initial axis and then reflected by a retro-reflector back substantially parallel to the initial axis, making a double pass through the transducer for increased measurement sensitivity. The preferred embodiment of the sensor head also includes a polarization state rotator and at least one beam splitter for orienting the beam along major and minor axes and for splitting the beam components into two signals which are independent converse amplitude-modulated signals carrying E-field magnitude and hence voltage information from the sensor head by way of optic fibers. 6 figs.
Measurements and characterization - Electro-optical characterization
Cook, G.
This brochure presents the capabilities that the Measurements and Characterization Division has in Electro-Optical Characterization, in which a variety of spectroscopy, ellipsometry, and capacitance techniques are used to probe the fundamental electrical and optical properties of solid-state materials.
Field analysis of electro-optic probes for minimally invasive microwave sampling.
Lee, Dong-Joon; Kwon, Jae-Yong; Kang, No-Weon
We numerically and experimentally investigate the field invasiveness of microwave signals using an electro-optic technique. The distortion of the standing wave voltage and pulse waveform probed by the electro-optic technique is explored through both minimally invasive external and non-invasive internal sensing configurations. First, we analyzed the continuous wave microwave field imaging on a millimeter- scale coaxial transmission line using a highly accurate and stable electro- optic scanning system. The electric field images from the microwave device are attained virtually non-invasively using a miniaturized fiber-coupled electro-optic probe. The accuracy of the field imaging associated with various probe styles is investigated by numerical analysis and experiment. Then, we analyzed the waveform of the coaxial transmission line up to 50 GHz using a pulsed electro-optic system with an external probe set. Finally, the invasive analysis was extended to the sub-millimeter-scale on-wafer coplanar waveguides, where the voltage waveforms are measured using a minimally invasive external probe as well as an internal wafer probe for non-invasive sampling. PMID:24663582
Electro-optic measurement of terahertz pulse energy distribution
NASA Astrophysics Data System (ADS)
Sun, J. H.; Gallacher, J. G.; Brussaard, G. J. H.; Lemos, N.; Issac, R.; Huang, Z. X.; Dias, J. M.; Jaroszynski, D. A.
An accurate and direct measurement of the energy distribution of a low repetition rate terahertz electromagnetic pulse is challenging because of the lack of sensitive detectors in this spectral range. In this paper, we show how the total energy and energy density distribution of a terahertz electromagnetic pulse can be determined by directly measuring the absolute electric field amplitude and beam energy density distribution using electro-optic detection. This method has potential use as a routine method of measuring the energy density of terahertz pulses that could be applied to evaluating future high power terahertz sources, terahertz imaging, and spatially and temporarily resolved pump-probe experiments.
Adaptive wiener image restoration kernel
Yuan, Ding
A method and device for restoration of electro-optical image data using an adaptive Wiener filter begins with constructing imaging system Optical Transfer Function, and the Fourier Transformations of the noise and the image. A spatial representation of the imaged object is restored by spatial convolution of the image using a Wiener restoration kernel.
Livermore Imaging Fourier Transform Infrared Spectrometer (LIFTIRS)
Carter, M.R.; Bennett, C.L.; Fields, D.J.; Lee, F.D.
Lawrence Livermore National Laboratory is currently operating a hyperspectral imager, the Livermore Imaging Fourier Transform Infrared Spectrometer (LIFTIRS). This instrument is capable of operating throughout the infrared spectrum from 3 to 12.5 {mu}m with controllable spectral resolution. In this presentation we report on it`s operating characteristics, current capabilities, data throughput and calibration issues.
Electro-optical rendezvous and docking sensors
NASA Technical Reports Server (NTRS)
Tubbs, David J.; Kesler, Lynn O.; Sirko, Robert J.
Electro-optical sensors provide unique and critical functionality for space missions requiring rendezvous, docking, and berthing. McDonnell Douglas is developing a complete rendezvous and docking system for both manned and unmanned missions. This paper examines our sensor development and the systems and missions which benefit from rendezvous and docking sensors. Simulation results quantifying system performance improvements in key areas are given, with associated sensor performance requirements. A brief review of NASA-funded development activities and the current performance of electro-optical sensors for space applications is given. We will also describe current activities at McDonnell Douglas for a fully functional demonstration to address specific NASA mission needs.
Polarization-independent electro-optic depolarizer
NASA Astrophysics Data System (ADS)
Heismann, F.; Tokuda, K. L.
We demonstrate a compact electro-optic polarization scrambler that depolarizes arbitrarily polarized light with less than 2.5% residual degree of polarization and variable depolarization times in the microsecond to millisecond range. The integrated-optic depolarizer is fabricated on lithium niobate and operates with a single-mode waveguide designed for a 1.5- mu m wavelength. The scrambler introduces negligible intensity modulation of less than 1.6% in the depolarized output light.
Electro-Optical High-Voltage Sensors
NASA Technical Reports Server (NTRS)
Gottsche, Allan; Johnston, Alan R.
Electro-optical sensors for measuring high voltages developed for use in automatically controlled power-distribution systems. Sensors connected to optoelectronic interrogating equipment by optical fibers. Because sensitive material and optical fibers are all dielectric, no problem in electrically isolating interrogating circuitry from high voltage, and no need for voltage dividers. Sensor signals transmitted along fibers immune to electromagnetic noise at radio and lower frequencies.
Electro-optical voltage sensor head
Woods, G.K.
A miniature electro-optic voltage sensor system capable of accurate operation at high voltages is disclosed. The system employs a transmitter, a sensor disposed adjacent to but out of direct electrical contact with a conductor on which the voltage is to be measured, a detector, and a signal processor. The transmitter produces a beam of electromagnetic radiation which is routed into the sensor where the beam undergoes the Pockels electro-optic effect. The electro-optic effect causes phase shifting in the beam, which is in turn converted to a pair of independent beams, from which the voltage of a system based on its E-field is determined when the two beams are normalized by the signal processor. The sensor converts the beam by splitting the beam in accordance with the axes of the beam`s polarization state (an ellipse whose ellipticity varies between -1 and +1 in proportion to voltage) into at least two AM signals. These AM signals are fed into a signal processor and processed to determine the voltage between a ground conductor and the conductor on which voltage is being measured. 6 figs.
Electro-optical voltage sensor head
Woods, Gregory K.
A miniature electro-optic voltage sensor system capable of accurate operation at high voltages. The system employs a transmitter, a sensor disposed adjacent to but out of direct electrical contact with a conductor on which the voltage is to be measured, a detector, and a signal processor. The transmitter produces a beam of electromagnetic radiation which is routed into the sensor where the beam undergoes the Pockels electro-optic effect. The electro-optic effect causes phase shifting in the beam, which is in turn converted to a pair of independent beams, from which the voltage of a system based on its E-field is determined when the two beams are normalized by the signal processor. The sensor converts the beam by splitting the beam in accordance with the axes of the beam's polarization state (an ellipse whose ellipticity varies between -1 and +1 in proportion to voltage) into at least two AM signals. These AM signals are fed into a signal processor and processed to determine the voltage between a ground conductor and the conductor on which voltage is being measured.
Linear Transformations Performed By An Electro-Optical Processor
NASA Astrophysics Data System (ADS)
Bromley, Keith; Monahan, Michael A.; Saxe, Steven G.
Abstract. This paper discusses the development of a noncoherent optical signal processing device, termed an electro-optical processor, and its application to performing discrete linear transformations. The device consists of a light-emitting diode (LED), a photographic matrix mask, and an area-array charge-coupled device (CCD). It is capable of performing matrix-vector products at high speed in a small, low-power, and potentially low-cost package. The operation of the processor and a sum-mary of methods for handling bipolar and complex arithmetic are briefly described. Then, consistent with the central theme of this book, em-phasis is placed upon the computation of linear transformations using this optical implementation. The transformations discussed are the cosine, Fourier, proportional-bandwidth spectral analysis, Karhunen-Loeve, sine, Mellin, Waish-Hadamard, Haar, and slant. Examples of the matrix masks for each of these transformations are shown along with a discussion of practical applications.
Single-shot electro-optic sampling of coherent transition radiation at the A0 Photoinjector
Maxwell, T.J.; Ruan, J.; Piot, P.; Thurman-Keup, R.; /Fermilab
Future collider applications and present high-gradient laser plasma wakefield accelerators operating with picosecond bunch durations place a higher demand on the time resolution of bunch distribution diagnostics. This demand has led to significant advancements in the field of electro-optic sampling over the past ten years. These methods allow the probing of diagnostic light such as coherent transition radiation or the bunch wakefields with sub-picosecond time resolution. Potential applications in shot-to-shot, non-interceptive diagnostics continue to be pursued for live beam monitoring of collider and pump-probe experiments. Related to our developing work with electro-optic imaging, we present results on single-shot electro-optic sampling of the coherent transition radiation from bunches generated at the A0 photoinjector.
Fourier analysis: from cloaking to imaging
NASA Astrophysics Data System (ADS)
Wu, Kedi; Cheng, Qiluan; Wang, Guo Ping
Regarding invisibility cloaks as an optical imaging system, we present a Fourier approach to analytically unify both Pendry cloaks and complementary media-based invisibility cloaks into one kind of cloak. By synthesizing different transfer functions, we can construct different devices to realize a series of interesting functions such as hiding objects (events), creating illusions, and performing perfect imaging. In this article, we give a brief review on recent works of applying Fourier approach to analysis invisibility cloaks and optical imaging through scattering layers. We show that, to construct devices to conceal an object, no constructive materials with extreme properties are required, making most, if not all, of the above functions realizable by using naturally occurring materials. As instances, we experimentally verify a method of directionally hiding distant objects and create illusions by using all-dielectric materials, and further demonstrate a non-invasive method of imaging objects completely hidden by scattering layers.
Nonlinear optical polymers for electro-optic signal processing
NASA Technical Reports Server (NTRS)
Lindsay, Geoffrey A.
Photonics is an emerging technology, slated for rapid growth in communications systems, sensors, imagers, and computers. Its growth is driven by the need for speed, reliability, and low cost. New nonlinear polymeric materials will be a key technology in the new wave of photonics devices. Electron-conjubated polymeric materials offer large electro-optic figures of merit, ease of processing into films and fibers, ruggedness, low cost, and a plethora of design options. Several new broad classes of second-order nonlinear optical polymers were developed at the Navy's Michelson Laboratory at China Lake, California. Polar alignment in thin film waveguides was achieved by electric-field poling and Langmuir-Blodgett processing. Our polymers have high softening temperatures and good aging properties. While most of the films can be photobleached with ultraviolet (UV) light, some have excellent stability in the 500-1600 nm range, and UV stability in the 290-310 nm range. The optical nonlinear response of these polymers is subpicosecond. Electro-optic switches, frequency doublers, light modulators, and optical data storage media are some of the device applications anticipated for these polymers.
Advances in automatic electro-optical tracking systems
NASA Astrophysics Data System (ADS)
Hughes, Andrew D.; Moy, Anthony J. E.
British Aerospace (Systems & Equipment) Ltd (BASE) has been working in the field of automatic electro-optical tracking (Autotrack) systems for more than 12 years. BASE Autotrack systems carry out the automatic detection, tracking and classification of missiles and targets using image processing techniques operating on data received from electro-optical sensors. Typical systems also produce control data to move the sensor platform, enabling moving targets to be tracked accurately over a wide range of conditions. BASE Autotrack systems have been well proven in land, sea and air applications. This paper discusses the relevance of Autotrack systems to modern high-technology warfare and charts the progress of their development with BASE, both with respect to current products and active research programs. Two third generation BASE Autotrack systems are described, one of which provided a sophisticated air-to-ground tracking capability in the recent Gulf War. The latest Autotrack product is also described; this uses ASIC and Transputer technology to provide a high-performance, compact, missile and target tracker. Reference is also made to BASE's research work. Topics include an ASIC correlator, point target detection and, in particular, the use of neural networks for real-time target classification.
Advances in automatic electro-optical tracking systems
NASA Astrophysics Data System (ADS)
Moy, Anthony J. E.; Hughes, Andrew D.
British Aerospace (Systems & Equipment) Ltd (BASE) has been working in the field of automatic electro-optical tracking (Autotrack) systems for more than 12 years. BASE Autotrack systems carry out the automatic detection, tracking and classification of missiles and targets using image processing techniques operating on data received from electro-optical sensors. Typical systems also produce control data to move the sensor platform, enabling moving targets to be tracked accurately over a wide range of conditions. BASE Autotrack systems have been well proven in land, sea and air applications. This paper discusses the relevance of Autotrack systems to modern high-technology warfare and charts the progress of their development within BASE, both with respect to current products and active research programs. Two third generation BASE Autotrack systems are described, one of which provided a sophisticated air-to-ground tracking capability in the recent Gulf War. The latest Autotrack product is also described; this uses ASIC and Transputer technology to provide a high-performance, compact, missile and target tracker. Reference is also made to BASE's research work. Topics include an ASIC correlator, point target detection and, in particular, the use of neural networks for real-time target classification.
Lead silicate microstructured optical fibres for electro-optical applications.
Zhang, Wen Qi; Manning, Sean; Ebendorff-Heidepriem, Heike; Monro, Tanya M
We report progress towards the realization of optical modulators based on electro-optic effects in soft glass fibres. A hybrid fabrication procedure was developed for producing microstructured lead silicate glass fibres with internal electrodes. Electro-optical characterization confirms experimentally that the enhanced nonlinear properties and superior isolation between the optical field and the electrodes make these fibres an ideal candidate platform for efficient electro-optical devices. PMID:24514705
Electro-optical properties of Rydberg excitons
NASA Astrophysics Data System (ADS)
Zielińska-Raczyńska, Sylwia; Ziemkiewicz, David; Czajkowski, Gerard
We show how to compute the electro-optical functions (absorption, reflection, and transmission) when Rydberg exciton-polaritons appear, including the effect of the coherence between the electron-hole pair and the electromagnetic field. With the use of the real density matrix approach, numerical calculations applied for the Cu2O crystal are performed. We also examine in detail and explain the dependence of the resonance displacement on the state number and applied electric field strength. We report a fairly good agreement with recently published experimental data.
Fourier removal of stripe artifacts in IRAS images
NASA Technical Reports Server (NTRS)
Van Buren, Dave
By working in the Fourier plane, approximate removal of stripe artifacts in IRAS images can be effected. The image of interest is smoothed and subtracted from the original, giving the high-spatial-frequency part. This 'filtered' image is then clipped to remove point sources and then Fourier transformed. Subtracting the Fourier components contributing to the stripes in this image from the Fourier transform of the original and transforming back to the image plane yields substantial removal of the stripes.
Electro-optics and lasers in Israel
NASA Astrophysics Data System (ADS)
Van Zwaren, Joesph
With over 3,000 scientists, engineers, and technicians spread out in some 86 companies, and in 10 universities and research institutes, all within less than a 2 hour drive from one another, Israel has no doubt one of the largest concentrations of researchers and skilled manpower in electro-optics and lasers in the world. This report presents an up-to-date picture of the field in Israel, covering the industry, academia and education. The recent wave of Russian immigration is bringing thousands of scientists and tens of thousands of engineers and is expected to make an impact on the field of electro-optics and lasers. A million immigrants from Russia are expected to come between 1990 and 1995. There were 3,700 scientists and 2,800 engineers among the first 200,000 Soviet immigrants. As most of this qualified manpower can not be expected to be absorbed by the existing industry, the Israeli government is actively encouraging local and foreign investors and local and multinational companies to help develop new and expanded high-tech enterprises in Israel. The Ministry of Industry and Trade has embarked upon a broad ranged program for industrial growth and immigrant absorption with the goal of doubling technology-based exports in the next four years. The Ministry of Science and Technology has started a program supporting R&D projects at the different universities for immigrant scientists with the goal of capitalizing on the talents of the newcomers to strengthen academia.
Poling of Microwave Electro-Optic Devices
NASA Technical Reports Server (NTRS)
Singer, Kenneth D.
The desire to transmit high frequency, microwave RF signals over fiber optic cables has necessitated the need for electro-optic modulation devices. However, in order to reap these potential benefits, it is necessary to develop the devices and their associated fabrication processes, particularly those processes associated with the poling of the devices. To this end, we entered into a cooperative research agreement with Richard Kunath of NASA LeRC. A graduate student in my group, Tony Kowalczyk, worked closely with the group at NASA to develop processes for construction of a microwave frequency electro-optic modulator. Materials were commercially obtained from Amoco Chemical and in collaboration with Lockheed-Martin. The photolithography processes were developed at NASA LeRC and the electric-field poling process was carried out in our laboratory at CWRU. During the grant period, the poling process conditions were investigated for these multilayer devices. Samples were poled and the resulting nonlinear optical properties were evaluated in our laboratory. Following the grant period, Kowalczyk went to NASA under a NRC fellowship, and I continued to collaborate as a consultant. Publications listed at the end of this report came out of this work. Another manuscript is in preparation and will be submitted shortly.
Electro-optic Phase Grating Streak Spectrometer
Goldin, F. J.
The electro-optic phase grating streak spectrometer (EOPGSS) generates a time-resolved spectra equivalent to that obtained with a conventional spectrometer/streak camera combination, but without using a streak camera (by far the more expensive and problematic component of the conventional system). The EOPGSS is based on a phase, rather than an amplitude grating. Further, this grating is fabricated of electro-optic material such as, for example, KD*P, by either etching grooves into an E-O slab, or by depositing lines of the E-O material onto an optical flat. An electric field normal to the grating alters the material's index of refraction and thus affects a shift (in angle) of the output spectrum. Ramping the voltage streaks the spectrum correspondingly. The streak and dispersion directions are the same, so a second (static, conventional) grating disperses the spectrum in the orthogonal direction to prevent different wavelengths from "overwriting" each other. Because the streaking is done by the grating, the streaked output spectrum is recorded with a time-integrating device, such as a CCD. System model, typical design, and performance expectations will be presented.
Defence electro-optics: European perspective
NASA Astrophysics Data System (ADS)
Hartikainen, Jari
In 2009 the United States invested in defence R&T 3,6 times and in defence research and development 6,8 times as much as all member states of the European Defence Agency (EDA) combined while the ratio in the total defence expenditure was 2,6 in the US' favour. The European lack of investments in defence research and development has a negative impact on the competitiveness of European defence industry and on the European non-dependence. In addition, the efficiency of investment is reduced due to duplication of work in different member states. The Lisbon Treaty tasks EDA to support defence technology research, and coordinate and plan joint research activities and the study of technical solutions meeting future operational needs. This paper gives an overview how EDA meets the challenge of improving the efficiency of European defence R&T investment with an emphasis on electro-optics and describes shortly the ways that governmental and industrial partners can participate in the EDA cooperation. Examples of joint R&T projects addressing electro-optics are presented.
Electro-optic resonant phase modulator
NASA Technical Reports Server (NTRS)
Chen, Chien-Chung (Inventor); Hemmati, Hamid (Inventor); Robinson, Deborah L. (Inventor)
An electro-optic resonant cavity is used to achieve phase modulation with lower driving voltages. Laser damage thresholds are inherently higher than with previously used integrated optics due to the utilization of bulk optics. Phase modulation is achieved at higher speeds with lower driving voltages than previously obtained with non-resonant electro-optic phase modulators. The instant scheme uses a data locking dither approach as opposed to the conventional sinusoidal locking schemes. In accordance with a disclosed embodiment, a resonant cavity modulator has been designed to operate at a data rate in excess of 100 megabits per sec. By carefully choosing the cavity finesse and its dimension, it is possible to control the pulse switching time to within 4 nano-sec. and to limit the required switching voltage to within 10 V. This cavity locking scheme can be applied by using only the random data sequence, and without the need of dithering of the cavity. Compared to waveguide modulators, the resonant cavity has a comparable modulating voltage requirement. Because of its bulk geometry, the resonant cavity modulator has the potential of accommodating higher throughput power. Mode matching into the bulk device is easier and typically can be achieved with higher efficiency. An additional control loop is incorporated into the modulator to maintain the cavity on resonance.
Electro-Optical Laser Technology. Curriculum Utilization. Final Report.
ERIC Educational Resources Information Center
Nawn, John H.
This report describes a program to prepare students for employment as laser technicians and laser operators and to ensure that they have the necessary skills required by the industry. The objectives are to prepare a curriculum and syllabus for an associate degree program in Electro-Optical Laser Technology. The 2-year Electro-Optical Laser program…
Electro-optical Probing Of Terahertz Integrated Circuits
NASA Technical Reports Server (NTRS)
Bhasin, K. B.; Romanofsky, R.; Whitaker, J. F.; Valdmanis, J. A.; Mourou, G.; Jackson, T. A.
Electro-optical probe developed to perform noncontact, nondestructive, and relatively noninvasive measurements of electric fields over broad spectrum at millimeter and shorter wavelengths in integrated circuits. Manipulated with conventional intregrated-circuit-wafer-probing equipment and operated without any special preparation of integrated circuits. Tip of probe small electro-optical crystal serving as proximity electric-field sensor.
Electro-optic device with gap-coupled electrode
Deri, Robert J.; Rhodes, Mark A.; Bayramian, Andrew J.; Caird, John A.; Henesian, Mark A.; Ebbers, Christopher A.
An electro-optic device includes an electro-optic crystal having a predetermined thickness, a first face and a second face. The electro-optic device also includes a first electrode substrate disposed opposing the first face. The first electrode substrate includes a first substrate material having a first thickness and a first electrode coating coupled to the first substrate material. The electro-optic device further includes a second electrode substrate disposed opposing the second face. The second electrode substrate includes a second substrate material having a second thickness and a second electrode coating coupled to the second substrate material. The electro-optic device additionally includes a voltage source electrically coupled to the first electrode coating and the second electrode coating.
Optical analysis of electro-optical systems by MTF calculus
NASA Astrophysics Data System (ADS)
Barbarini, Elisa Signoreto; Dos Santos, Daniel, Jr.; Stefani, Mário Antonio; Yasuoka, Fátima Maria Mitsue; Castro Neto, Jarbas C.; Rodrigues, Evandro Luís Linhari
One of the widely used methods for performance analysis of an optical system is the determination of the Modulation Transfer Function (MTF). The MTF represents a quantitative and direct measure of image quality, and, besides being an objective test, it can be used on concatenated optical system. This paper presents the application of software called SMTF (software modulation transfer function), built in C++ and Open CV platforms for MTF calculation on electro-optical system. Through this technique, it is possible to develop specific method to measure the real time performance of a digital fundus camera, an infrared sensor and an ophthalmological surgery microscope. Each optical instrument mentioned has a particular device to measure the MTF response, which is being developed. Then the MTF information assists the analysis of the optical system alignment, and also defines its resolution limit by the MTF graphic. The result obtained from the implemented software is compared with the theoretical MTF curve from the analyzed systems.
Electro-optical tunable birefringent filter
Levinton, Fred M.
An electrically tunable Lyot type filter is a Lyot that include one or more filter elements. Each filter element may have a planar, solid crystal comprised of a material that exhibits birefringence and is electro-optically active. Transparent electrodes may be coated on each face of the crystal. An input linear light polarizer may be located on one side of the crystal and oriented at 45 degrees to the optical axis of the birefringent crystal. An output linear light polarizer may be located on the other side of the crystal and oriented at -45 degrees with respect to the optical axis of the birefringent crystal. When an electric voltage is applied between the electrodes, the retardation of the crystal changes and so does the spectral transmission of the optical filter.
Electrically actuated elastomers for electro optical modulators
NASA Astrophysics Data System (ADS)
Galler, N.; Ditlbacher, H.; Steinberger, B.; Hohenau, A.; Dansachmüller, M.; Camacho-Gonzales, F.; Bauer, S.; Krenn, J. R.; Leitner, A.; Aussenegg, F. R.
By using an elastomer as dielectric medium in a parallel plate capacitor, the attractive forces between the differently charged electrodes strongly compress that layer, representing a special type of electrostrictive effect. With an optical interference technique at the metal-insulator-metal layer system we studied the temporal behaviour of this mechanical deformation. We show that the deformation can be enhanced when the capacitor is laterally structured in order to allow the elastomer volume between the electrodes to move laterally, resulting in typical response times below 1 ms. The elastomer together with the metal electrodes is a metal-insulator-metal optical waveguide, whose mode properties can be tuned by electrically controlled mechanical thickness changes, suggesting applications for low-price electro optical modulators with response speeds comparable to thermo optical polymer modulators but with much smaller size.
Electro-optical graphene plasmonic logic gates.
Ooi, Kelvin J A; Chu, Hong Son; Bai, Ping; Ang, Lay Kee
The versatile control of graphene's plasmonic modes via an external gate-voltage inspires us to design efficient electro-optical graphene plasmonic logic gates at the midinfrared wavelengths. We show that these devices are superior to the conventional optical logic gates because the former possess cut-off states and interferometric effects. Moreover, the designed six basic logic gates (i.e., NOR/AND, NAND/OR, XNOR/XOR) achieved not only ultracompact size lengths of less than λ/28 with respect to the operating wavelength of 10 μm, but also a minimum extinction ratio as high as 15 dB. These graphene plasmonic logic gates are potential building blocks for future nanoscale midinfrared photonic integrated circuits. PMID:24690855
Efficiently poled electro-optic polymer modulators.
Qiu, Feng; Yokoyama, Shiyoshi
A titanium dioxide (TiO2) / electro-optic (EO) polymer hybrid waveguide modulator was designed and fabricated. This modulator possessed a significant advantage for realizing high poling efficiency regardless of the EO polymer resistivity. The in-device EO coefficient was measured to be 100 pm/V, which was 32% higher than that of the thin polymer film. As a result, the phase modulator displayed a VπL figure of merit of 3.5 V∙cm at 1550 nm, which can be reduced further in a push-pull Mach-Zehnder interferometer structure. Temporal stability test of the modulator at 85°C indicated only 8% change of Vπ over 500 hours. The propagation loss in the waveguide was measured as ~3 dB/cm. PMID:27557181
Linear electro-optical properties of zincite
NASA Astrophysics Data System (ADS)
Shaldin, Yu. V.
Orientational, dispersion, and temperature dependences of electro-optical coefficients of Li-doped ZnO single crystals are investigated. According to the data on the orientational dependences obtained far from the electronic absorption band, the values of all linearly independent components of the Pockels tensor are specified. In the range from 2 eV to E g , at both 100 and 300 K, the dispersion obeys a power law with m=2, which indicates a two-dimensional character of the van Hove singularity. The anomalies in the temperature dependences in the range from 15 to 700 K are explained by the competing contributions of the anharmonicities of the electron and lattice subsystems, which lead to anomalous behavior of the coefficients at both low ( T < 100 K) and high ( T > 100 K) temperatures. In the low-temperature range, the identified anomalies correlate with data of independent measurements of birefringence, spontaneous polarization, and dilatometry.
Electro-optic high voltage sensor
Davidson, James R.; Seifert, Gary D.
A small sized electro-optic voltage sensor capable of accurate measurement of high voltages without contact with a conductor or voltage source is provided. When placed in the presence of an electric field, the sensor receives an input beam of electromagnetic radiation. A polarization beam displacer separates the input beam into two beams with orthogonal linear polarizations and causes one linearly polarized beam to impinge a crystal at a desired angle independent of temperature. The Pockels effect elliptically polarizes the beam as it travels through the crystal. A reflector redirects the beam back through the crystal and the beam displacer. On the return path, the polarization beam displacer separates the elliptically polarized beam into two output beams of orthogonal linear polarization. The system may include a detector for converting the output beams into electrical signals and a signal processor for determining the voltage based on an analysis of the output beams.
Electro-optical hybrid slip ring
NASA Astrophysics Data System (ADS)
Hong, En
The slip ring is a rotary electrical interface, collector, swivel or rotary joint. It is a physical system that can perform continuous data transfer and data exchange between a stationary and a rotating structure. A slip ring is generally used to transfer data or power from an unrestrained, continuously rotating electro-mechanical system in real-time, thereby simplifying operations and eliminating damage-prone wires dangling from moving joints. Slip rings are widely used for testing, evaluating, developing and improving various technical equipment and facilities with rotating parts. They are widely used in industry, especially in manufacturing industries employing turbo machinery, as in aviation, shipbuilding, aerospace, defense, and in precise facilities having rotating parts such as medical Computerized Tomography (CT) and MRI scanners and so forth. Therefore, any improvement in slip ring technology can impact large markets. Research and development in this field will have broad prospects long into the future. The goal in developing the current slip ring technology is to improve and increase the reliability, stability, anti-interference, and high data fidelity between rotating and stationary structures. Up to now, there have been numerous approaches used for signal and data transfer utilizing a slip ring such as metal contacts, wires, radio transmission, and even liquid media. However, all suffer from drawbacks such as data transfer speed limitations, reliability, stability, electro-magnetic interference and durability. The purpose of the current research is to break through these basic limitations using an optical solution, thereby improving performance in current slip ring applications. This dissertation introduces a novel Electro-Optical Hybrid Slip Ring technology, which makes "through the air" digital-optical communication between stationary and rotating systems a reality with high data transfer speed, better reliability and low interference susceptibility
Electro-optic high voltage sensor
Davidson, James R.; Seifert, Gary D.
A small sized electro-optic voltage sensor capable of accurate measurement of high levels of voltages without contact with a conductor or voltage source is provided. When placed in the presence of an electric field, the sensor receives an input beam of electromagnetic radiation into the sensor. A polarization beam displacer serves as a filter to separate the input beam into two beams with orthogonal linear polarizations. The beam displacer is oriented in such a way as to rotate the linearly polarized beams such that they enter a Pockels crystal having at a preferred angle of 45 degrees. The beam displacer is therefore capable of causing a linearly polarized beam to impinge a crystal at a desired angle independent of temperature. The Pockels electro-optic effect induces a differential phase shift on the major and minor axes of the input beam as it travels through the Pockels crystal, which causes the input beam to be elliptically polarized. A reflecting prism redirects the beam back through the crystal and the beam displacer. On the return path, the polarization beam displacer separates the elliptically polarized beam into two output beams of orthogonal linear polarization representing the major and minor axes. The system may include a detector for converting the output beams into electrical signals, and a signal processor for determining the voltage based on an analysis of the output beams. The output beams are amplitude modulated by the frequency of the electric field and the amplitude of the output beams is proportional to the magnitude of the electric field, which is related to the voltage being measured.
Efficient single pixel imaging in Fourier space
NASA Astrophysics Data System (ADS)
Bian, Liheng; Suo, Jinli; Hu, Xuemei; Chen, Feng; Dai, Qionghai
Single pixel imaging (SPI) is a novel technique capturing 2D images using a bucket detector with a high signal-to-noise ratio, wide spectrum range and low cost. Conventional SPI projects random illumination patterns to randomly and uniformly sample the entire scene's information. Determined by Nyquist sampling theory, SPI needs either numerous projections or high computation cost to reconstruct the target scene, especially for high-resolution cases. To address this issue, we propose an efficient single pixel imaging technique (eSPI), which instead projects sinusoidal patterns for importance sampling of the target scene's spatial spectrum in Fourier space. Specifically, utilizing the centrosymmetric conjugation and sparsity priors of natural images' spatial spectra, eSPI sequentially projects two \\tfrac{π }{2}-phase-shifted sinusoidal patterns to obtain each Fourier coefficient in the most informative spatial frequency bands. eSPI can reduce requisite patterns by two orders of magnitude compared to conventional SPI, which helps a lot for fast and high-resolution SPI.
Optical image encryption based on multifractional Fourier transforms.
Zhu, B; Liu, S; Ran, Q
We propose a new image encryption algorithm based on a generalized fractional Fourier transform, to which we refer as a multifractional Fourier transform. We encrypt the input image simply by performing the multifractional Fourier transform with two keys. Numerical simulation results are given to verify the algorithm, and an optical implementation setup is also suggested. PMID:18066153
Determining electro-optic coefficients for lithium tantalate using an electro-optic scanning device
Casson, J. L.; Gahagan, K. T.; Robinson, J. M.; Scrymgeour, D. A.; Jain, R.
We demonstrate a ferroelectric optical device based on single crystal LiTaO{sub 3} that can scan a laser beam from the visible to the infrared. It utilizes the electro-optic effect in the ferroelectric that has potentially high intrinsic response times of GHz. There are many applications to such scanning devices in the infrared such as optical switching, spectrometry, microscopy, and sensing. Lithium tantalate has two ferroelectric polarization states that are antiparallel (180{sup o}) to each other. The domain states can be reversed by applying an electric field of {approx}21 kV/mm at room temperature. By reversing the domain structure in the crystal, we can create domains in the crystal of almost any desired shape. By creating prism-shaped domain, we can create a ferroelectric deflector or scanner by applying either static or sweeping voltages across the crystal. This scanner is capable of scanning wavelengths from 0.4-5 {micro}m. The scanning performance varied from a total deflection angle of 13.38{sup o} at 1558 nm to 16.18{sup o} at 632.8 nm. Since the amount of deflection of the incoming light is determined by the applied voltage, the electro-optic coefficient and other fixed quantities, by measuring the deflection angle as a function of wavelength, the dispersion of the electro-optic coefficient in lithium tantalate can be determined. In these experiments, the scanner was characterized from the visible (632.8 nm) to midinfrared (1558 nm). Both extraordinary and the ordinary polarizations of light were used, in order to determine the electro-optic coefficients, r{sup 33} and r{sup 31}. Except for the values at 632.8 nm, these values of the electro-optic coefficients have not been previously reported. For lithium tantalate, r{sup 33} at 632.8 nm is reported in the literature as 30.2 pm/V. We found that this decreases to 27.1 pm/V at 1558 nm. For the extraordinary polarization, r{sup 13} varied from 7.55 pm/V (632.8 nm) to 6.84 pm/V (1558 nm).
Photoinduced electro-optics measurements of biosilica transformation to cristobalite
Fuchs, Ido; Aluma, Yaniv; Ilan, Micha; Kityk, Iwan; Mastai, Yitzhak
In this paper we studied the photoinduced electro optics effects in the thermal transformation process of biosilica to cristobalite, at a relatively low temperature and ambient pressure. This process was characterized by a variety of standards techniques with emphasis on linear electro optic effect measurements. Overall we demonstrated that photoinduced electro optics measurements are very sensitive to the transformation from amorphous structure of silica in the natural sponge samples to laminar string morphology of cristobalite. With this technique we could probe the change in the samples chirality from achiral bio silica to chiral cristobalite structure. Furthermore it is shown that natural biosilica have photoinduced linear electro optics respond indicating the chiral natural of biosilica. - Graphical abstract: The phase transformation of biosilica from marine sponges to Cristobalite under thermal treatment was investigated using photoinduced electro optics measurements. The figure shows the changes of the electro-optic coefficient of cristobalite and biosilica. - Highlights: • We examine phase transformation of biosilica. • We report transition from amorphous biosilica to crystalline Cristobalite. • Biosilica transformation to Cristobalite at temperature of 850 °C. • Biosilica transformation is studied with photoinduced measurements. • We examine changes in the photoinduced linear electro optics properties.
Compact snapshot birefringent imaging Fourier transform spectrometer
NASA Astrophysics Data System (ADS)
Kudenov, Michael W.; Dereniak, Eustace L.
The design and implementation of a compact multiple-image Fourier transform spectrometer (FTS) is presented. Based on the multiple-image FTS originally developed by A. Hirai, the presented device offers significant advantages over his original implementation. Namely, its birefringent nature results in a common-path interferometer which makes the spectrometer insensitive to vibration. Furthermore, it enables the potential of making the instrument ultra-compact, thereby improving the portability of the sensor. The theory of the birefringent FTS is provided, followed by details of its specific embodiment. A laboratory proof of concept of the sensor, designed and developed at the Optical Detection Lab, is also presented. Spectral measurements of laboratory sources are provided, including measurements of light-emitting diodes and gas-discharge lamps. These spectra are verified against a calibrated Ocean Optics USB2000 spectrometer. Other data were collected outdoors, demonstrating the sensor's ability to resolve spectral signatures in standard outdoor lighting and environmental conditions.
A new electro-optic waveguide architecture and the unprecedented devices it enables
NASA Astrophysics Data System (ADS)
Davis, Scott R.; Rommel, Scott D.; Farca, George; Anderson, Michael H.
A new electro-optic waveguide platform, which provides unprecedented electro-optical phase delays (> 1mm), with very low loss (< 0.5 dB/cm) and rapid response time (sub millisecond), is presented. This technology, developed by Vescent Photonics, is based upon a unique liquid-crystal waveguide geometry, which exploits the tremendous electro-optic response of liquid crystals while circumventing historic limitations of liquid crystals. The exceedingly large optical phase delays accessible with this technology enable the design and construction of a new class of previously unrealizable photonic devices. Examples include: a 1-D non-mechanical, analog beamsteerer with an 80° field of regard, a chip-scale widely tunable laser, a chip-scale Fourier transform spectrometer (< 5 nm resolution demonstrated), widely tunable micro-ring resonators, tunable lenses, ultra-low power (< 5 microWatts) optical switches, true optical time delay (up to 10 ns), and many more. All of these devices may benefit from established manufacturing technologies and ultimately may be as inexpensive as a calculator display. Furthermore, this new integrated photonic architecture has applications in a wide array of commercial and defense markets including: remote sensing, micro-LADAR, OCT, laser illumination, phased array radar, optical communications, etc. Performance attributes of several example devices are presented.
Electro-optic properties of hybrid solgel doped with a nonlinear chromophore with large hyperpolarizability.
Zhang, Hong Xi; Lu, Dong; Peyghambarian, Nasser; Fallahi, Mahmoud; Luo, Jing Dong; Chen, Bao Quan; Jen, Alex K Y
We report the electro-optic properties of hybrid silica solgel doped with a nonlinear chromophore with large hyperpolarizability. Electro-optic coefficients of higher than 30 pm/V have been obtained. Moreover, the electro-optic coefficients have good temporal stability and show promise for the development of high-speed electro-optic devices. PMID:15675685
Photoinduced electro-optics measurements of biosilica transformation to cristobalite
NASA Astrophysics Data System (ADS)
Fuchs, Ido; Aluma, Yaniv; Ilan, Micha; Kityk, Iwan; Mastai, Yitzhak
In this paper we studied the photoinduced electro optics effects in the thermal transformation process of biosilica to cristobalite, at a relatively low temperature and ambient pressure. This process was characterized by a variety of standards techniques with emphasis on linear electro optic effect measurements. Overall we demonstrated that photoinduced electro optics measurements are very sensitive to the transformation from amorphous structure of silica in the natural sponge samples to laminar string morphology of cristobalite. With this technique we could probe the change in the samples chirality from achiral bio silica to chiral cristobalite structure. Furthermore it is shown that natural biosilica have photoinduced linear electro optics respond indicating the chiral natural of biosilica.
Highly Sensitive Electro-Optic Modulators
DeVore, Peter S
There are very important diagnostic and communication applications that receive faint electrical signals to be transmitted over long distances for capture. Optical links reduce bandwidth and distance restrictions of metal transmission lines; however, such signals are only weakly imprinted onto the optical carrier, resulting in low fidelity transmission. Increasing signal fidelity often necessitates insertion of radio-frequency (RF) amplifiers before the electro-optic modulator, but (especially at high frequencies) RF amplification results in large irreversible distortions. We have investigated the feasibility of a Sensitive and Linear Modulation by Optical Nonlinearity (SALMON) modulator to supersede RF-amplified modulators. SALMON uses cross-phase modulation, a manifestation of the Kerr effect, to enhance the modulation depth of an RF-modulated optical wave. This ultrafast process has the potential to result in less irreversible distortions as compared to a RF-amplified modulator due to the broadband nature of the Kerr effect. Here, we prove that a SALMON modulator is a feasible alternative to an RFamplified modulator, by demonstrating a sensitivity enhancement factor greater than 20 and significantly reduced distortion.
Electro-optical spin measurement system
NASA Technical Reports Server (NTRS)
Fodale, Robert (Inventor); Hampton, Herbert R. (Inventor)
An electro-optical spin measurement system for a spin model in a spin tunnel includes a radio controlled receiver/transmitter, targets located on the spin model, optical receivers mounted around the perimeter of the spin tunnel and the base of the spin tunnel for receiving data from the targets, and a control system for accumulating data from the radio controlled receiver and receivers. Six targets are employed. The spin model includes a fuselage, wings, nose, and tail. Two targets are located under the fuselage of the spin model at the nose tip and tail. Two targets are located on the side of the fuselage at the nose tip and tail, and a target is located under each wing tip. The targets under the fuselage at the nose tip and tail measure spin rate of the spin model, targets on the side of the fuselage at the nose tip and tail measure angle of attack of the spin model, and the targets under the wing tips measure roll angle of the spin model. Optical receivers are mounted at 90 degree increments around the periphery of the spin tunnel to determine angle of attack and roll angle measurements of the spin model. Optical receivers are also mounted at the base of the spin tunnel to define quadrant and position of the spin model and to determine the spin rate of the spin model.
Hybrid electro-optically modulated microcombs.
Del'Haye, Pascal; Papp, Scott B; Diddams, Scott A
Optical frequency combs based on mode-locked lasers have proven to be invaluable tools for a wide range of applications in precision spectroscopy and metrology. A novel principle of optical frequency comb generation in whispering-gallery mode microresonators ("microcombs") has been developed recently, which represents a promising route towards chip-level integration and out-of-the-lab use of these devices. Presently, two families of microcombs have been demonstrated: Combs with electronically detectable mode spacing that can be directly stabilized, and broadband combs with up to octave-spanning spectra but mode spacings beyond electronic detection limits. However, it has not yet been possible to achieve these two key requirements simultaneously, as will be critical for most microcomb applications. Here we present a route to overcome this problem by interleaving an electro-optic comb with the spectrum from a parametric microcomb. This allows, for the first time, direct control and stabilization of a microcomb spectrum with large mode spacing (>140 GHz) with no need for an additional mode-locked laser frequency comb. The attained residual 1-sec instability of the microcomb comb spacing is 10(-15), with a microwave reference limited absolute instability of 10(-12) at a 140 GHz mode spacing. PMID:23368562
Experimental studies of electro-optic polymer modulators and waveguides
NASA Astrophysics Data System (ADS)
Hedin, Eric R.; Goetz, Frederick J.
The results of an experimental study of electro-optic modulators and waveguides based on polymeric materials are presented. Included are the design, fabrication, and testing of integrated Mach-Zehnder modulators, which are based on polymer films that contain a novel, nonlinear electro-optic chromophore. Studies also show the efficacy of photolithography or photobleaching by the use of this chromophore to form passive, branching waveguides, which are operated at the 1300-nm wavelength.
Terahertz wave electro-optic measurements with optical spectral filtering
Ilyakov, I. E. Shishkin, B. V.; Kitaeva, G. Kh.; Akhmedzhanov, R. A.
We propose electro-optic detection techniques based on variations of the laser pulse spectrum induced during pulse co-propagation with terahertz wave radiation in a nonlinear crystal. Quantitative comparison with two other detection methods is made. Substantial improvement of the sensitivity compared to the standard electro-optic detection technique (at high frequencies) and to the previously shown technique based on laser pulse energy changes is demonstrated in experiment.
Development of electro-optical instrumentation for reactor safety studies
Turko, B.T.; Kolbe, W.F.; Leskovar, B.; Sun, R.K.
The development of new electro-optical instrumentation for reactor safety studies is described. The system measures the thickness of the water film and droplet size and velocity distributions which would be encountered in the annular two-phase flow in a reactor cooling system. The water film thickness is measured by a specially designed capacitance system with a short time constant. Water droplet size and velocity are measured by a subsystem consisting of a continuously pulsed laser light source, a vidicon camera, a video recorder, and an automatic image analyzer. An endoscope system attached to the video camera is used to image the droplets. Each frame is strobed with two accurately spaced uv light pulses, from two sequentially fired nitrogen lasers. The images are stored in the video disk recorder. The modified automatic image analyzer is programmed to digitize the droplet size and velocity distributions. Many special optical, mechanical and electronic system components were designed and fabricated. They are described in detail, together with calibration charts and experimental results.
Identification of handheld objects for electro-optic/FLIR applications
NASA Astrophysics Data System (ADS)
Moyer, Steve K.; Flug, Eric; Edwards, Timothy C.; Krapels, Keith A.; Scarbrough, John
This paper describes research on the determination of the fifty-percent probability of identification cycle criterion (N50) for two sets of handheld objects. The first set consists of 12 objects which are commonly held in a single hand. The second set consists of 10 objects commonly held in both hands. These sets consist of not only typical civilian handheld objects but also objects that are potentially lethal. A pistol, a cell phone, a rocket propelled grenade (RPG) launcher, and a broom are examples of the objects in these sets. The discrimination of these objects is an inherent part of homeland security, force protection, and also general population security. Objects were imaged from each set in the visible and mid-wave infrared (MWIR) spectrum. Various levels of blur are then applied to these images. These blurred images were then used in a forced choice perception experiment. Results were analyzed as a function of blur level and target size to give identification probability as a function of resolvable cycles on target. These results are applicable to handheld object target acquisition estimates for visible imaging systems and MWIR systems. This research provides guidance in the design and analysis of electro-optical systems and forward-looking infrared (FLIR) systems for use in homeland security, force protection, and also general population security.
Holographic Optical Elements with Electro-optic Control
NASA Astrophysics Data System (ADS)
Ermold, Michael Leigh
mirrors from a theoretical and experimental perspective. Presented here are methods of formation, their optical and electro-optic properties, the device morphology and its relation to the observed properties, and a theoretical model for the have also been observed through the use of optical measurements, optical and electron imaging. I will also discuss implications when HOEs are used in imaging and non-imaging applications.
External electro-optic sampling utilizing a poled polymer asymmetric Fabry Perot cavity as an electro-optical probe tip
NASA Astrophysics Data System (ADS)
Chen, Kaixin; Zhang, Hongbo; Zhang, Daming; Yang, Han; Yi, Maobin
External electro-optic sampling utilizing a poled polymer asymmetry Fabry-Perot cavity as electro-optic probe tip has been demonstrated. Electro-optical polymer spin coated on the high-reflectivity mirror (HRM) was corona poled. Thus, an asymmetric F-P cavity was formed based on the different reflectivity of the polymer and HRM and it converted the phase modulation that originates from electro-optic effect of the poled polymer to amplitude modulation, so only one laser beam is needed in this system. The principle of the sampling was analyzed by multiple reflection and index ellipsoid methods. A 1.2 GHz microwave signal propagating on coplanar waveguide transmission line was sampled, and the voltage sensitivity about 0.5 mV/ Hz was obtained.
Electro-Optical Design for Efficient Visual Communication
NASA Technical Reports Server (NTRS)
Huck, Friedrich O.; Fales, Carl L.; Jobson, Daniel J.; Rahman, Zia-Ur
Visual communication, in the form of telephotography and television, for example, can be regarded as efficient only if the amount of information that it conveys about the scene to the observer approaches the maximum possible and the associated cost approaches the minimum possible. Elsewhere we have addressed the problem of assessing the end to end performance of visual communication systems in terms of their efficiency in this sense by integrating the critical limiting factors that constrain image gathering into classical communications theory. We use this approach to assess the electro-optical design of image gathering devices as a function of the f number and apodization of the objective lens and the aperture size and sampling geometry of the phot-detection mechanism. Results show that an image gathering device that is designed to optimize information capacity performs similarly to the human eye. For both, the performance approaches the maximum possible, in terms of the efficiency with which the acquired information can be transmitted as decorrelated data, and the fidelity, sharpness, and clearity with which fine detail can be restored.
Underwater electro-optical system for mine identification
NASA Astrophysics Data System (ADS)
Strand, Michael P.
The Electro-Optic Identification (EOID) Sensors project is developing a Laser Visual Iidentification Sensor (LVIS) for identification of proud, partially buried, and moored mines in shallow water/very shallow water. LVIS will be deployed in small diameter underwater vehicles, including unmanned underwater vehicles (UUVs). Since the mission is mine identification, LVIS must: a) deliver high quality images in turbid coastal waters, while b) being compatible with the size and power constraints imposed by the intended deployment platforms. This project is sponsored by the Office of Naval Research, as a part of the AOA Mine Reconnaissance/Hunter program. High quality images which retain target detail and contrast are required for mine identification. LVIS will be designed to produce images of minelike contacts (MLC) of sufficient quality to allow identification while operating in turbid coastal waters from a small diameter UUV. Technology goals for the first generation LVIS are a) identification range up to 40 feet for proud, partially buried, and moored MLCs under coastal water conditions; b) day/night operation from a UUV operating at speeds up to 4 knots; c) power consumption less than 500 watts, with 275 watts being typical; and d) packaged within a 32-inch long portion of a 21-inch diameter vehicle section.
Imaging Fourier transform spectrometry of chemical plumes
NASA Astrophysics Data System (ADS)
Bradley, Kenneth C.; Gross, Kevin C.; Perram, Glen P.
A midwave infrared (MWIR) imaging Fourier transform spectrometer (FTS), the Telops FIRST-MWE (Field-portable Imaging Radiometric Spectrometer Technology - Midwave Extended) has been utilized for the standoff detection and characterization of chemical plumes. Successful collection and analysis of MWIR hyperspectral imagery of jet engine exhaust has allowed us to produce spatial profiles of both temperature and chemical constituent concentrations of exhaust plumes. Successful characterization of this high temperature combustion event has led to the collection and analysis of hyperspectral imagery of lower temperature emissions from industrial smokestacks. This paper presents MWIR data from remote collection of hyperspectral imagery of methyl salicilate (MeS), a chemical warfare agent simulant, during the Chemical Biological Distributed Early Warning System (CBDEWS) test at Dugway Proving Grounds, UT in 2008. The data did not contain spectral lines associated with emission of MeS. However, a few broad spectral features were present in the background-subtracted plume spectra. Further analysis will be required to assign these features, and determine the utility of MWIR hyperspectral imagery for analysis of chemical warfare agent plumes.
Color image registration based on quaternion Fourier transformation
NASA Astrophysics Data System (ADS)
Wang, Qiang; Wang, Zhengzhi
The traditional Fourier Mellin transform is applied to quaternion algebra in order to investigate quaternion Fourier transformation properties useful for color image registration in frequency domain. Combining with the quaternion phase correlation, we propose a method for color image registration based on the quaternion Fourier transform. The registration method, which processes color image in a holistic manner, is convenient to realign color images differing in translation, rotation, and scaling. Experimental results on different types of color images indicate that the proposed method not only obtains high accuracy in similarity transform in the image plane but also is computationally efficient.
Electro-optic polymers: Materials and devices
NASA Astrophysics Data System (ADS)
Derose, Christopher Todd
Electro-optic (EO) polymers are an attractive alternative to inorganic nonlinear materials. EO polymers with a Pockel's coefficient, r33, greater than 320 pm/V have been recently demonstrated. In addition to their high EO activity, EO polymers have the additional benefit that their dielectric constants at optical and millimeter wave frequencies are closely matched which allow for bandwidths which are limited only by the resistive losses of traveling wave electrodes. The amorphous nature of the host polymer makes heterogeneous integration of the materials on any substrate possible. The devices which will have the most immediate impact based on these recent materials developments are EO waveguide modulators. Performance benchmarks of less than 6 dB insertion loss, sub-volt Vpi and greater than 100 GHz bandwidth have been achieved separately however, the challenge of achieving all of these benchmarks in a single device has not yet been met. The aim of this dissertation is to optimize passive materials to achieve efficient in device poling of EO polymers, optimize the chromophore loading of the active polymers and to optimize waveguide modulators for device performance within a particular system, analog RF photonic links. These optimizations were done by defining figures of merit for the materials and modulators. This research strategy has led to significant improvements in poling efficiency as well as modulators with record low insertion losses which maintain a low Vpi on the order of 1--2 Volts. Using this optimization strategy and state of the art EO polymers, devices which meet or surpass the benchmark performance values in all categories are expected in the near future.
Electro-optic properties of organic nanotubes.
Stoylov, Stoyl P; Stoilova-McPhie, Svetla
In this review article the theoretical and experimental possibilities of applying EO-methods for estimation of the physico-chemical properties of the organic nanotubes (ONTs) are studied. The ONTs are highly organized nanostructures of strongly elongated, anysometric, and hollow cylinders with a size range of 1 nm to 10,000 nm, e.g. in aqueous solutions they could behave as colloid (disperse) particles. They have high interaction ability due to their extremely large curved, rolled-up external surfaces (bilayers of membrane walls) and unique properties because of their specific electric charge distribution and dynamics that make possible the functionalization of their surfaces. Thus they could template guestsubstances such as membrane proteins and protein complexes on the exterior surfaces and in the membrane. We performed our investigations for the case of ONT aqueous colloid suspension. Following our earlier proposition of the general expression for the electro-optic (EO) effect we derived equations for the evaluation of the electric properties of ONT particles such as mechanism of electric polarization and identification of their most important electric Dipole Moments (DM), permanent (pDM) and induced (iDMs). Further we recommend ways for the calculation of their magnitude and direction. Also we evaluated some geometrical properties such as length of the ONT particles and their polydispersity. The knowledge that we provided about the ONT properties may enable us to elucidate and predict their biological activity. Templating biological active ligands (such as membrane proteins and protein complexes) on the inner and outer surfaces as well as in the surface membrane creates their potential usefulness as carrier and deliverer of biopharmaceuticals in bio-nanodevices. The theoretical equations were compared with the experimental data for ONTs such as (lipid) LNT, Tobacco Mosaic Virus (TMV) and microtubules (MT). Comparison of EO methods with other methods used till
Automatic Suppression of Intense Monochromatic Light in Electro-Optical Sensors
Ritt, Gunnar; Eberle, Bernd
Electro-optical imaging sensors are widely distributed and used for many different tasks. Due to technical improvements, their pixel size has been steadily decreasing, resulting in a reduced saturation capacity. As a consequence, this progress makes them susceptible to intense point light sources. Developments in laser technology have led to very compact and powerful laser sources of any wavelength in the visible and near infrared spectral region, offered as laser pointers. The manifold of wavelengths makes it difficult to encounter sensor saturation over the complete operating waveband by conventional measures like absorption or interference filters. We present a concept for electro-optical sensors to suppress overexposure in the visible spectral region. The key element of the concept is a spatial light modulator in combination with wavelength multiplexing. This approach allows spectral filtering within a localized area in the field of view of the sensor. The system offers the possibility of automatic reduction of overexposure by monochromatic laser radiation. PMID:23202039
Electro-optical (EO) target and background simulation
NASA Astrophysics Data System (ADS)
Denney, Dwight L.; Yin, Young-Koh
A computer based thermal scene simulation was developed for generating synthetic images to facilitate the design and test of missile born Electro-Optical (EO) seeker systems. A scene is composed of objects and a background selected from the available data base files. Objects are modeled by combining small planar facets to cover their three dimensional surface. Each facet is associated in the data base with the thermal and optical properties of the surface being modeled. The objects may be stationary or mobile. The background is modeled on the interior surface of a pyramid defining the extent of the scene, with the floor of the pyramid representing the earth surface and the sides of the pyramid representing above horizon. The pyramid surface is then divided into triangular facets. Each facet is assigned a uniform texture selected from the database of background materials. The simulation is designed to be used with missile 6 degree of freedom (6DOF) simulations, and generates images as seen by the seeker based on the instantaneous seeker line of sight, seeker position, seeker orientation, object orientations and positions, and background.
Speckle size in optical Fourier domain imaging
NASA Astrophysics Data System (ADS)
Lamouche, G.; Vergnole, S.; Bisaillon, C.-E.; Dufour, M.; Maciejko, R.; Monchalin, J.-P.
As in conventional time-domain optical coherence tomography (OCT), speckle is inherent to any Optical Fourier Domain Imaging (OFDI) of biological tissue. OFDI is also known as swept-source OCT (SS-OCT). The axial speckle size is mainly determined by the OCT resolution length and the transverse speckle size by the focusing optics illuminating the sample. There is also a contribution from the sample related to the number of scatterers contained within the probed volume. In the OFDI data processing, there is some liberty in selecting the range of wavelengths used and this allows variation in the OCT resolution length. Consequently the probed volume can be varied. By performing measurements on an optical phantom with a controlled density of discrete scatterers and by changing the probed volume with different range of wavelengths in the OFDI data processing, there is an obvious change in the axial speckle size, but we show that there is also a less obvious variation in the transverse speckle size. This work contributes to a better understanding of speckle in OCT.
Configuration of electro-optic fire source detection system
NASA Astrophysics Data System (ADS)
Fabian, Ram Z.; Steiner, Zeev; Hofman, Nir
The recent fighting activities in various parts of the world have highlighted the need for accurate fire source detection on one hand and fast "sensor to shooter cycle" capabilities on the other. Both needs can be met by the SPOTLITE system which dramatically enhances the capability to rapidly engage hostile fire source with a minimum of casualties to friendly force and to innocent bystanders. Modular system design enable to meet each customer specific requirements and enable excellent future growth and upgrade potential. The design and built of a fire source detection system is governed by sets of requirements issued by the operators. This can be translated into the following design criteria: I) Long range, fast and accurate fire source detection capability. II) Different threat detection and classification capability. III) Threat investigation capability. IV) Fire source data distribution capability (Location, direction, video image, voice). V) Men portability. ) In order to meet these design criteria, an optimized concept was presented and exercised for the SPOTLITE system. Three major modular components were defined: I) Electro Optical Unit -Including FLIR camera, CCD camera, Laser Range Finder and Marker II) Electronic Unit -including system computer and electronic. III) Controller Station Unit - Including the HMI of the system. This article discusses the system's components definition and optimization processes, and also show how SPOTLITE designers successfully managed to introduce excellent solutions for other system parameters.
Seaborne electro-optical sensors and their technologies
NASA Astrophysics Data System (ADS)
Horman, Stephen R.; Headley, Robert M., Jr.; Zurasky, Matthew W.; Dezeeuw, Patrick A.; Trahan, Joseph W.
The US Navy (USN) has long placed a strong emphasis on the production and use of electro-optical (EO) sensors for a wide variety of mission on naval aircraft. Numerous EO fire control and surveillance sensor systems have been developed for USN surface ship applications, but production and deployment has been limited. This apparent dichotomy is due to the vastly different missions and environments of aircraft and ships, and to the need for shipboard system that will support operations dictated by our global interest. EO technology has now evolved to the point where surveillance and fire control sensor systems can be built that have excellent performance under the preponderance of environmental conditions, and where atmospheric refraction, rather than transmission, is the primary design driver. In addition, the consensus of USN decision-makers is that EO sensor system that are designed to complement not supplant, radar systems can provide dramatic improvements in combat system performance at acceptable costs. The two sensor classes that have achieved this level of maturity are Horizon IR Surveillance Systems and the Thermal Imaging Sensors. This paper describes the technologies that have made these sensors possible as well as some of the phenomenological drivers to their designs.
Electro optical design for a space camera based on MODTRAN data analysis
NASA Astrophysics Data System (ADS)
Haghshenas, Javad
Electro-Optical design of a push-broom space camera for a Low Earth Orbit (LEO) remote sensing satellite is discussed in this paper. An atmosphere analysis is performed based on ModTran algorithm and the total radiance of visible light reached to the camera entrance diameter is simulated by Atmosphere radiative transfer software PcModWin. Simulation is done for various conditions of sun zenith angles and earth surface albedos to predict the signal performance in different times and locations. According to the proposed simulation of total radiance incidence, appropriate linear CCD is chosen and then an optical design is done to completely satisfy electro-optics requirements. Optical design is based on Schmidt-Cassegrain scheme, which results in simple fabrication and high accuracy. Proposed electro-optical camera satisfies 5.9 meter ground resolution with image swath of higher than 23 km on the earth surface. Satellite is assumed to be at 681km altitude with 6.8km/s ground track speed.
The electro-optical and electrochromic properties of electrolyte-liquid crystal dispersions
NASA Astrophysics Data System (ADS)
Cupelli, Daniela; De Filpo, Giovanni; Chidichimo, Giuseppe; Nicoletta, Fiore Pasquale
Liquid crystals are known to exhibit a reversible color change by applying a direct current electric field, if a small amount of quaternary ammonium salts is dissolved into them. Applications of such an electrochromic liquid crystal cell have been proposed as interesting laser-addressed writing and image storage devices. Liquid crystal dispersions are composite materials formed by liquid crystal droplets embedded in either a polymer or a monomer matrix. Thin films of liquid crystal dispersions can be turned from an opaque to a transparent state by application of a suitable alternating current electric field. Herein, we report our investigations on electrolyte-liquid crystal dispersions, which show independent electro-optical and electrochromic properties characterized by fast bleaching times. This cell involves the reorientation of liquid crystal molecules, trapped in droplets, for the electro-optical changes from the opaque to transparent state and the formation of complexes at the cathode, between the positive ions of electrolyte and liquid crystal dispersed in the matrix, for the electrochromic changes from the bleached to colored state. The device is able to change its electro-optical transmittance within few milliseconds and its color within few seconds.
Novel electro-optical coupling technique for magnetic resonance-compatible positron emission tomography detectors.
Olcott, Peter D; Peng, Hao; Levin, Craig S
A new magnetic resonance imaging (MRI)-compatible positron emission tomography (PET) detector design is being developed that uses electro-optical coupling to bring the amplitude and arrival time information of high-speed PET detector scintillation pulses out of an MRI system. The electro-optical coupling technology consists of a magnetically insensitive photodetector output signal connected to a nonmagnetic vertical cavity surface emitting laser (VCSEL) diode that is coupled to a multimode optical fiber. This scheme essentially acts as an optical wire with no influence on the MRI system. To test the feasibility of this approach, a lutetium-yttrium oxyorthosilicate crystal coupled to a single pixel of a solid-state photomultiplier array was placed in coincidence with a lutetium oxyorthosilicate crystal coupled to a fast photomultiplier tube with both the new nonmagnetic VCSEL coupling and the standard coaxial cable signal transmission scheme. No significant change was observed in 511 keV photopeak energy resolution and coincidence time resolution. This electro-optical coupling technology enables an MRI-compatible PET block detector to have a reduced electromagnetic footprint compared with the signal transmission schemes deployed in the current MRI/PET designs. PMID:19397853
Electro-Optical Effects in Thin Organic Films
NASA Technical Reports Server (NTRS)
Leyderman, Alexander; Penn, Benjamin G.
Meta-nitroaniline (mNA) and 2-cyclo-octylamino-5-nitropyridine (COANP) single crystals were grown between two transparent fused quartz plates on which indium-tin-oxide layers were deposited. Both linear and quadratic electro-optic effects of the crystals were examined by an ac modulation method. The figures of merit for mNA and COANP are estimated to be 3.2(10-12 m/V and 4.2(10-12 m/V, respectively. It was found that the crystals were under good protection of the cells and the figure of merits of the crystals did not decrease with time. It is believed that the method adopted in the paper is applicable to electro-optic cell fabrication with other compounds if those crystals growth from melt is feasible. It is suggested that the electro-optic cells have potential fortune because of their durability and relative easy manipulation processes of crystal growth.
Electro-optically spectrum tailorable intracavity optical parametric oscillator.
Chung, H P; Chang, W K; Tseng, C H; Geiss, R; Pertsch, T; Chen, Y H
We report a unique, pulsed intracavity optical parametric oscillator (IOPO) whose output spectrum is electro-optically (EO) tailorable based on an aperiodically poled lithium niobate (APPLN) working simultaneously as an optical parametric gain medium and an active gain spectrum filter in the system. We have successfully obtained from the IOPO the emission of single to multiple narrow-line signal spectral peaks in a near-infrared (1531 nm) band simply by electro-optic control. The power spectral density of the EO tailored signal can be enhanced by up to 10 times over the original (nontailored) signal. PMID:26565817
Fourier transform imaging spectropolarimeter using simultaneous polarization modulation.
Meng, Xin; Li, Jianxin; Liu, Defang; Zhu, Rihong
We introduce a Fourier transform imaging spectropolarimeter composed of a simultaneous polarization modulator and a Fourier transform spectrometer without slit. The spectropolarimeter enables the generation of four sets of fringe patterns with different polarization states of light from an object point. Fourier transform of the fringe patterns provides four equations of Stokes parameters in various wavenumbers. And we can obtain the full-stokes vector from the equations. The most significant advantage of the method is that the four polarized fringe patterns are obtained simultaneously and separated without aliasing. Additionally, the advantages of the Fourier transform spectrometer are maintained, such as high radiative throughput. PMID:23455296
Electro-Optical Sensing Apparatus and Method for Characterizing Free-Space Electromagnetic Radiation
Zhang, Xi-Cheng; Libelo, Louis Francis; Wu, Qi
Apparatus and methods for characterizing free-space electromagnetic energy, and in particular, apparatus/method suitable for real-time two-dimensional far-infrared imaging applications are presented. The sensing technique is based on a non-linear coupling between a low-frequency electric field and a laser beam in an electro-optic crystal. In addition to a practical counter-propagating sensing technique, a co-linear approach is described which provides longer radiated field--optical beam interaction length, thereby making imaging applications practical.
Double image encryption based on iterative fractional Fourier transform
NASA Astrophysics Data System (ADS)
Liu, Zhengjun; Liu, Shutian
We present an image encryption algorithm to simultaneously encrypt two images into a single one as the amplitudes of fractional Fourier transform with different orders. From the encrypted image we can get two original images independently by fractional Fourier transforms with two different fractional orders. This algorithm can be independent of additional random phases as the encryption/decryption keys. Numerical results are given to analyze the capability of this proposed method. A possible extension to multi-image encryption with a fractional order multiplexing scheme has also been given.
[Research of dual-photoelastic-modulator-based beat frequency modulation and Fourier-Bessel transform imaging spectrometer].
Wang, Zhi-Bin; Zhang, Rui; Wang, Yao-Li; Huang, Yan-Fei; Chen, You-Hua; Wang, Li-Fu; Yang, Qiang
As the existing photoelastic-modulator(PEM) modulating frequency in the tens of kHz to hundreds of kHz between, leading to frequency of modulated interference signal is higher, so ordinary array detector cannot effectively caprure interference signal..A new beat frequency modulation method based on dual-photoelastic-modulator (Dual-PEM) and Fourier-Bessel transform is proposed as an key component of dual-photoelastic-modulator-based imaging spectrometer (Dual-PEM-IS) combined with charge coupled device (CCD). The dual-PEM are operated as an electro-optic circular retardance modulator, Operating the PEMs at slightly different resonant frequencies w1 and w2 respectively, generates a differential signal at a much lower heterodyne frequency that modulates the incident light. This method not only retains the advantages of the existing PEM, but also the frequency of modulated photocurrent decreased by 2-3 orders of magnitude (10-500 Hz) and can be detected by common array detector, and the incident light spectra can be obtained by Fourier-Bessel transform of low frequency component in the modulated signal. The method makes the PEM has the dual capability of imaging and spectral measurement. The basic principle is introduced, the basic equations is derived, and the feasibility is verified through the corresponding numerical simulation and experiment. This method has' potential applications in imaging spectrometer technology, and analysis of the effect of deviation of the optical path difference. This work provides the necessary theoretical basis for remote sensing of new Dual-PEM-IS and for engineering implementation of spectra inversion. PMID:24822442
Solid state electro-optic color filter and iris
NASA Technical Reports Server (NTRS)
Test results obtained have confirmed the practicality of the solid state electro-optic filters as an optical control element in a television system. Neutral-density control range in excess of 1000:1 has been obtained on sample filters. Test results, measurements in a complete camera system, discussions of problem areas, analytical comparisons, and recommendations for future investigations are included.
Laser Electro-Optic Technology. Florida Vocational Program Guide.
ERIC Educational Resources Information Center
University of South Florida, Tampa. Dept. of Adult and Vocational Education.
This program guide identifies primary considerations in the organization, operation, and evaluation of a laser electro-optic technology program. An occupational description and program content are presented. A curriculum framework specifies the exact course title, course number, levels of instruction, major course content, laboratory activities,…
Laser Electro-Optic Engineering Technology. Florida Vocational Program Guide.
ERIC Educational Resources Information Center
University of South Florida, Tampa. Dept. of Adult and Vocational Education.
This program guide identifies particular considerations in the organization, operation, and evaluation of laser electro-optic engineering technology programs. Contents include an occupational description and information on the following: program content, including a curriculum framework that details major concepts and intended outcomes and a list…
Linearized Bragg grating assisted electro-optic modulator.
Khurgin, Jacob B; Morton, Paul A
We propose a new linearized electro-optic modulator in which linearization is achieved by modulating the index of a Bragg grating reflector placed in the arm(s) of a Michelson Interferometer. This grating-assisted Michelson (GAMI) modulator can operate as either an intensity or amplitude modulator, and is shown to significantly improve the linearity of microwave photonics links. PMID:25503037
Electro-optic contribution to Raman scattering from alkali halides
Mahan, G.D.; Subbaswamy, K.R.
The electro-optic contributions to second-order Raman scattering and field-induced first-order scattering from alkali halides are calculated explicitly in terms of the ionic hyperpolarizability coefficients. The relevant local-field corrections are evaluated. Illustrative numerical results are presented.
Coherent electro-optical detection of THz-wave generated from synchronously pumped picosecond THz parametric oscillator
NASA Astrophysics Data System (ADS)
Takida, Yuma; Ohira, Tatsuya; Tadokoro, Yuzuru; Kumagai, Hiroshi; Nashima, Shigeki
Terahertz (THz) radiation via parametric down-conversion of optical pulses in a nonlinear optical crystal is an attractive way to develop frequency tunable THz-wave sources. Therefore, we have focused on developing low-laser-powerpumped THz-wave parametric sources and then successfully demonstrated a synchronously-pumped picosecond THz parametric oscillator (TPO) in pump-enhanced idler-resonant cavity with a bulk 5 mol% MgO-doped lithium niobate (MgO:LN) crystal. In this paper, toward coherent electro-optical (EO) detection of THz waves generated from our synchronously pumped picosecond TPO, we reported time-domain measurements of the THz electric fields using a bowtie- shaped low-temperature grown gallium arsenide (LT-GaAs) photoconductive (PC) antenna as a THz detector. As a result, we obtained temporal waveforms of the THz electric pulses, for the different number of Si-prism couplers, and then found that the radiated THz waves separated multiple unanticipated pulses by use of the arrayed-prism coupling technique. Also, we compared the time-domain system with a Fourier transform Michelson interferometer using a highresistance silicon (Si) beam splitter, from the some viewpoints. The present results reveal great prospects for the realization of THz spectroscopy and imaging applications using our THz-wave source.
Fourier domain OCT imaging of American cockroach nervous system
NASA Astrophysics Data System (ADS)
Wyszkowska, Joanna; Gorczynska, Iwona; Ruminski, Daniel; Karnowski, Karol; Kowalczyk, Andrzej; Stankiewicz, Maria; Wojtkowski, Maciej
In this pilot study we demonstrate results of structural Fourier domain OCT imaging of the nervous system of Periplaneta americana L. (American cockroach). The purpose of this research is to develop an OCT apparatus enabling structural imaging of insect neural system. Secondary purpose of the presented research is to develop methods of the sample preparation and handling during the OCT imaging experiments. We have performed imaging in the abdominal nerve cord excised from the American cockroach. For this purpose we have developed a Fourier domain / spectral OCT system operating at 820 nm wavelength range.
Fourier Spectral Filter Array for Optimal Multispectral Imaging.
Jia, Jie; Barnard, Kenneth J; Hirakawa, Keigo
Limitations to existing multispectral imaging modalities include speed, cost, range, spatial resolution, and application-specific system designs that lack versatility of the hyperspectral imaging modalities. In this paper, we propose a novel general-purpose single-shot passive multispectral imaging modality. Central to this design is a new type of spectral filter array (SFA) based not on the notion of spatially multiplexing narrowband filters, but instead aimed at enabling single-shot Fourier transform spectroscopy. We refer to this new SFA pattern as Fourier SFA, and we prove that this design solves the problem of optimally sampling the hyperspectral image data. PMID:26849867
Invariant quaternion radial harmonic Fourier moments for color image retrieval
NASA Astrophysics Data System (ADS)
Xiang-yang, Wang; Wei-yi, Li; Hong-ying, Yang; Pan-pan, Niu; Yong-wei, Li
Moments and moment invariants have become a powerful tool in image processing owing to their image description capability and invariance property. But, conventional methods are mainly introduced to deal with the binary or gray-scale images, and the only approaches for color image always have poor color image description capability. Based on radial harmonic Fourier moments (RHFMs) and quaternion, we introduced the quaternion radial harmonic Fourier moments (QRHFMs) for representing color images in this paper, which can be seen as the generalization of RHFMs for gray-level images. It is shown that the QRHFMs can be obtained from the RHFMs of each color channel. We derived and analyzed the rotation, scaling, and translation (RST) invariant property of QRHFMs. We also discussed the problem of color image retrieval using invariant QRHFMs. Experimental results are provided to illustrate the efficiency of the proposed color image representation.
Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS): Imaging and Tracking Capability
NASA Technical Reports Server (NTRS)
Zhou, D. K.; Larar, A. M.; Liu, Xu; Reisse, R. A.; Smith, W. L.; Revercomb, H. E.; Bingham, G. E.; Zollinger, L. J.; Tansock, J. J.; Huppi, Ronald J.
The geosynchronous-imaging Fourier transform spectrometer (GIFTS) engineering demonstration unit (EDU) is an imaging infrared spectrometer designed for atmospheric soundings. It measures the infrared spectrum in two spectral bands (14.6 to 8.8 microns, 6.0 to 4.4 microns) using two 128 128 detector arrays with a spectral resolution of 0.57/cm with a scan duration of approx. 11 seconds. From a geosynchronous orbit, the instrument will have the capability of taking successive measurements of such data to scan desired regions of the globe, from which atmospheric status, cloud parameters, wind field profiles, and other derived products can be retrieved. The GIFTS EDU provides a flexible and accurate testbed for the new challenges of the emerging hyperspectral era. The EDU ground-based measurement experiment, held in Logan, Utah during September 2006, demonstrated its extensive capabilities and potential for geosynchronous and other applications (e.g., Earth observing environmental measurements). This paper addresses the experiment objectives and overall performance of the sensor system with a focus on the GIFTS EDU imaging capability and proof of the GIFTS measurement concept.
Prototype positron emission tomography insert with electro-optical signal transmission for simultaneous operation with MRI
NASA Astrophysics Data System (ADS)
Olcott, Peter; Kim, Ealgoo; Hong, Keyjo; Lee, Brian J.; Grant, Alexander M.; Chang, Chen-Ming; Glover, Gary; Levin, Craig S.
The simultaneous acquisition of PET and MRI data shows promise to provide powerful capabilities to study disease processes in human subjects, guide the development of novel treatments, and monitor therapy response and disease progression. A brain-size PET detector ring insert for an MRI system is being developed that, if successful, can be inserted into any existing MRI system to enable simultaneous PET and MRI images of the brain to be acquired without mutual interference. The PET insert uses electro-optical coupling to relay all the signals from the PET detectors out of the MRI system using analog modulated lasers coupled to fiber optics. Because the fibers use light instead of electrical signals, the PET detector can be electrically decoupled from the MRI making it partially transmissive to the RF field of the MRI. The SiPM devices and low power lasers were powered using non-magnetic MRI compatible batteries. Also, the number of laser-fiber channels in the system was reduced using techniques adapted from the field of compressed sensing. Using the fact that incoming PET data is sparse in time and space, electronic circuits implementing constant weight codes uniquely encode the detector signals in order to reduce the number of electro-optical readout channels by 8-fold. Two out of a total of sixteen electro-optical detector modules have been built and tested with the entire RF-shielded detector gantry for the PET ring insert. The two detectors have been tested outside and inside of a 3T MRI system to study mutual interference effects and simultaneous performance with MRI. Preliminary results show that the PET insert is feasible for high resolution simultaneous PET/MRI imaging for applications in the brain.
Prototype positron emission tomography insert with electro-optical signal transmission for simultaneous operation with MRI.
Olcott, Peter; Kim, Ealgoo; Hong, Keyjo; Lee, Brian J; Grant, Alexander M; Chang, Chen-Ming; Glover, Gary; Levin, Craig S
The simultaneous acquisition of PET and MRI data shows promise to provide powerful capabilities to study disease processes in human subjects, guide the development of novel treatments, and monitor therapy response and disease progression. A brain-size PET detector ring insert for an MRI system is being developed that, if successful, can be inserted into any existing MRI system to enable simultaneous PET and MRI images of the brain to be acquired without mutual interference. The PET insert uses electro-optical coupling to relay all the signals from the PET detectors out of the MRI system using analog modulated lasers coupled to fiber optics. Because the fibers use light instead of electrical signals, the PET detector can be electrically decoupled from the MRI making it partially transmissive to the RF field of the MRI. The SiPM devices and low power lasers were powered using non-magnetic MRI compatible batteries. Also, the number of laser-fiber channels in the system was reduced using techniques adapted from the field of compressed sensing. Using the fact that incoming PET data is sparse in time and space, electronic circuits implementing constant weight codes uniquely encode the detector signals in order to reduce the number of electro-optical readout channels by 8-fold. Two out of a total of sixteen electro-optical detector modules have been built and tested with the entire RF-shielded detector gantry for the PET ring insert. The two detectors have been tested outside and inside of a 3T MRI system to study mutual interference effects and simultaneous performance with MRI. Preliminary results show that the PET insert is feasible for high resolution simultaneous PET/MRI imaging for applications in the brain. PMID:25856511
Fractional Fourier transform in temporal ghost imaging with classical light
Setaelae, Tero; Shirai, Tomohiro; Friberg, Ari T.
We investigate temporal, second-order classical ghost imaging with long, incoherent, scalar plane-wave pulses. We prove that in rather general conditions, the intensity correlation function at the output of the setup is given by the fractional Fourier transform of the temporal object. In special cases, the correlation function is shown to reduce to the ordinary Fourier transform and the temporal image of the object. Effects influencing the visibility and the resolution are considered. This work extends certain known results on spatial ghost imaging into the time domain and could find applications in temporal tomography of pulses.
Theoretical study of Fourier-transform acousto-optic imaging.
Barjean, Kinia; Ramaz, François; Tualle, Jean-Michel
We propose a full theoretical study of Fourier-transform acousto-optic imaging, which we recently introduced and experimentally assessed in [Opt. Lett.40, 705-708 (2015)OPLEDP0146-959210.1364/OL.40.000705] as an alternative to achieve axial resolution in acousto-optic imaging with a higher signal-to-noise ratio. PMID:27140883
Motion compensation for electro-optical line scanner sensors using incomplete data
NASA Astrophysics Data System (ADS)
Power, Gregory J.
When imaging the ground from the air, distortions can occur if the imagery was created form an electro-optical line scanner pointing to nadir and mounted on the bottom of an airborne platform. The inability of the aircraft to maintain a perfect trajectory can cause the distortions. In the worst case scenario, camera stabilizers fail, no geographical reference or navigation data is available, and the sensor periodically fails leaving incomplete data for image construction. Motion compensation can restore the images. This paper describes various distortions that can be created for an airborne nadir-aimed line scanner. A motion-compensation technique is introduced that combines multiple cues from geographical reference and navigation data as well as line-scan matched filtering. A semi- automated restoration implementation is introduced followed by the automated line-scan matched filter implementation. These various compensation techniques provide backup for each other thus creating a more efficient motion- compensation system. Even in the worst case scenario, the system continues to attempt motion compensation using an optimal line-scan matched filtering technique. The results of using this automated technique for motion compensation is demonstrated using simulated high-definition imagery and then using actual electro-optical and hyperspectral images that were obtained form the Dynamic Data Base (DDB) program sponsored by the Defense Advanced Research Projects Agency (DARPA).
A new generation of previously unrealizable photonic devices as enabled by a unique electro-optic waveguide architecture
NASA Astrophysics Data System (ADS)
Davis, Scott R.; Rommel, Scott D.; Farca, George; Anderson, Michael H.
A new electro-optic waveguide platform, which provides unprecedented electro-optical phase delays (> 1mm), with very low loss (< 0.5 dB/cm) and rapid response time (sub millisecond), is presented. This technology, developed by Vescent Photonics, is based upon a unique liquid-crystal waveguide geometry, which exploits the tremendous electro-optic response of liquid crystals while circumventing historic limitations of liquid crystals. The exceedingly large optical phase delays accessible with this technology enable the design and construction of a new class of previously unrealizable photonic devices. Examples include: a 1-D non-mechanical, analog beamsteerer with an 80° field of regard, a chip-scale widely tunable laser, a chip-scale Fourier transform spectrometer (< 5 nm resolution demonstrated), widely tunable micro-ring resonators, tunable lenses, ultra-low power (< 5 microWatts) optical switches, true optical time delay (up to 10 ns), and many more. All of these devices may benefit from established manufacturing technologies and ultimately may be as inexpensive as a calculator display. Furthermore, this new integrated photonic architecture has applications in a wide array of commercial and defense markets including: remote sensing, micro-LADAR, OCT, laser illumination, phased array radar, optical communications, etc. Performance attributes of several example devices are presented.
Proposal of snapshot line-imaging Fourier spectroscopy for smartphone
NASA Astrophysics Data System (ADS)
Kawashima, Natsumi; Sato, Shun; Ishida, Akane; Inohara, Daichi; Tanaka, Naotaka; Wada, Kenji; Nishiyama, Akira; Fujiwara, Masaru; Ishimaru, Ichiro
We propose the extremely-compact-size line-imaging Fourier spectroscopy for smartphones. We realize the near common-path interferometer with strong robustness for mechanical vibrations by installing the transmission-type relative-inclined phase-shifter. The interferogram of an imaging line is formed as 2-dimensional fringe pattern on imaging sensor, such as CCD camera. In other words, the horizontal axis on an imaging sensor is assigned to phase-shift value. And the vertical axis is corresponds to image formation coordinate. Thus, by installing a relatively-inclined thin glass into imaging optics, such as smartphone, we will realize the line-imaging Fourier spectroscopy for healthcare sensor in daily-life environments.
Monocular electro-optical stereo scanner
NASA Technical Reports Server (NTRS)
Vermillion, C.; Maurer, H.; Salomonson, V.; Cote, C.; Catena, J.; Rampariyan, H.; Smith, J.
MEOSS is a single optics and single spectral band camera. Three CCD's working in pushbroom mode are mounted perpendicular to the flight direction on a common focal plate. Their oblique views of + and - 23 degrees forward and backward, as well as nadir oriented, lead to threefold stereoscopic images. This principle allows a nearly simultaneous generation of all three images of a stereo triplet. The time gap between the forward and aft looking images guarantees constant illumination conditions. The ground resolution of MEOSS will be 52 by 80 m ground pixel size, height resolution of 55 m and swath width of 255 km. The drifting ground coverage pattern of MEOSS is unique compared to polar orbiting satellites and will allow images of an area to be taken at different times of the day. A scene will consist of 3144 scan lines, with each having 3236 pixels. The data will be received by the Deep Space Network of JPL Goldstone and mailed to Goddard.
Monocular electro-optical stereo scanner
NASA Astrophysics Data System (ADS)
Vermillion, C.; Maurer, H.; Salomonson, V.; Cote, C.; Catena, J.; Rampariyan, H.; Smith, J.
MEOSS is a single optics and single spectral band camera. Three CCD's working in pushbroom mode are mounted perpendicular to the flight direction on a common focal plate. Their oblique views of + and - 23 degrees forward and backward, as well as nadir oriented, lead to threefold stereoscopic images. This principle allows a nearly simultaneous generation of all three images of a stereo triplet. The time gap between the forward and aft looking images guarantees constant illumination conditions. The ground resolution of MEOSS will be 52 by 80 m ground pixel size, height resolution of 55 m and swath width of 255 km. The drifting ground coverage pattern of MEOSS is unique compared to polar orbiting satellites and will allow images of an area to be taken at different times of the day. A scene will consist of 3144 scan lines, with each having 3236 pixels. The data will be received by the Deep Space Network of JPL Goldstone and mailed to Goddard.
Automatic Laser Glare Suppression in Electro-Optical Sensors
Ritt, Gunnar; Eberle, Bernd
Progress in laser technology has led to very compact but nevertheless powerful laser sources. In the visible and near infrared spectral region, lasers of any wavelength can be purchased. Continuous wave laser sources pose an especially serious threat to the human eye and electro-optical sensors due to their high proliferation and easy availability. The manifold of available wavelengths cannot be covered by conventional safety measures like absorption or interference filters. We present a protection concept for electro-optical sensors to suppress dazzling in the visible spectral region. The key element of the concept is the use of a digital micromirror device (DMD) in combination with wavelength multiplexing. This approach allows selective spectral filtering in defined regions of interest in the scene. The system offers the possibility of automatic attenuation of dazzling laser radiation. PMID:25569754
Electroluminescent devices with function of electro-optic shutter.
Song, Seongkyu; Jeong, Jaewook; Chung, Seok Hwan; Jeong, Soon Moon; Choi, Byeongdae
The polymer-dispersed liquid crystal (PDLC) was used as a dielectric layer of electroluminescent (EL) device to provide multi-function of electroluminescence and electro-optic shutter. A 50 μm-thick PDLC layer was formed between a transparent electrode and a ZnS:Cu phosphor layer. The electro-optic properties of the EL device were not distorted by the introduction of the PDLC layer. The extraction efficiency of luminescence was improved by more than 14% by PDLC layer. The transmittance of the PDLC was also founded not to be degraded significantly by excitation frequency. Therefore, the electroluminescence of the device was ignited by excitation frequency at a given voltage for full transparency of the PDLC. This device has great potential for applications in transparent displays with the function of a privacy window. PMID:23037230
Electro-optical sensor with automatic suppression of laser dazzling
NASA Astrophysics Data System (ADS)
Ritt, G.; Eberle, B.
The progress in laser technology leads to very compact but nevertheless powerful laser sources. In the visible and near infrared spectral region, lasers of any wavelength can be purchased. Especially continuous wave laser sources pose a serious threat to the human eye and electro-optical sensors due to their high proliferation and easy availability. The manifold of wavelengths cannot be encountered by conventional safety measures like absorption or interference filters. We present a protection concept for electro-optical sensors to suppress dazzling in the visible spectral region. The key element of the concept is the use of a digital micromirror device (DMD) in combination with wavelength multiplexing. This approach allows selective spectral filtering in defined regions of interest in the scene. The system offers the possibility of automatic attenuation of dazzling laser radiation. An anti-dazzle algorithm comprises the analysis of the laser wavelength and the subsequent activation of the appropriate micromirrors of the DMD.
Electro-optic techniques in electron beam diagnostics
van Tilborg, Jeroen; Toth, Csaba; Matlis, Nicholas; Plateau, Guillaume; Leemans, Wim
Electron accelerators such as laser wakefield accelerators, linear accelerators driving free electron lasers, or femto-sliced synchrotrons, are capable of producing femtosecond-long electron bunches. Single-shot characterization of the temporal charge profile is crucial for operation, optimization, and application of such accelerators. A variety of electro-optic sampling (EOS) techniques exists for the temporal analysis. In EOS, the field profile from the electron bunch (or the field profile from its coherent radiation) will be transferred onto a laser pulse co-propagating through an electro-optic crystal. This paper will address the most common EOS schemes and will list their advantages and limitations. Strong points that all techniques share are the ultra-short time resolution (tens of femtoseconds) and the single-shot capabilities. Besides introducing the theory behind EOS, data from various research groups is presented for each technique.
Automatic laser glare suppression in electro-optical sensors.
Ritt, Gunnar; Eberle, Bernd
Progress in laser technology has led to very compact but nevertheless powerful laser sources. In the visible and near infrared spectral region, lasers of any wavelength can be purchased. Continuous wave laser sources pose an especially serious threat to the human eye and electro-optical sensors due to their high proliferation and easy availability. The manifold of available wavelengths cannot be covered by conventional safety measures like absorption or interference filters. We present a protection concept for electro-optical sensors to suppress dazzling in the visible spectral region. The key element of the concept is the use of a digital micromirror device (DMD) in combination with wavelength multiplexing. This approach allows selective spectral filtering in defined regions of interest in the scene. The system offers the possibility of automatic attenuation of dazzling laser radiation. PMID:25569754
Intraocular electro-optic lens with ciliary muscle controlled accommodation.
Doornaert, Dries; Glorieux, Christ; De Gersem, Herbert; Puers, Robert; Spileers, Werner; Blanckaert, Johan
In this paper a concept is proposed of an intraocular lens implant with electro-optic accommodation of a variable-focus hybrid liquid-crystal-based lens. The dioptric strength of the lens is electronically controlled by a signal that is derived from the change of inductance of a sensing coil due to a marker implanted in the nearby contracting or decontracting ciliary muscle. Analytical, numerical and experimental results are reported on the dependency of the frequency of a Colpitts oscillator circuit on the location of a nearby conductive marker. A concept is also reported on the use as an electro-optic lens of a device based on a liquid crystal in planar alignment, which is held between a flat and a curved window coated with optically transparent and electrically conductive layers. PMID:24110406
[Spatially modulated Fourier transform imaging spectrometer data compression research].
Huang, Min; Xiangli, Bin; Yuan, Yan; Shen, Zhong; Lu, Qun-bo; Wang, Zhong-hou; Liu, Xue-bin
Fourier transform imaging spectrometer is a new technic, and has been developed very fast in recent ten years. When it is used in satellite, because of the limit by the data transmission, the authors need to compress the original data obtained by the Fourier transform imaging spectrometer, then, the data can be transmitted, and can be incepted on the earth and decompressed. Then the authors can do data process to get spectrum data which can be used by user. Data compression technic used in Fourier transform imaging spectrometer is a new technic, and few papers introduce it at home and abroad. In this paper the authors will give a data compression method, which has been used in EDIS, and achieved a good result. PMID:20302132
Electro-optical Tuning of Fabry-Perot Interferometers
NASA Technical Reports Server (NTRS)
Schwemmer, G. K.
Compact unit operates much faster than conventional piezoelectric scanners. High voltage creates electric field in Pockels cell, changing refractive properties. Cell changes optical path length between mirrors without mechanically moving anything in gap. High voltage varied rapidly to scan interferometer. Voltage applied longitudinally or transversely, depending on type of Pockels cell. New electro-optic scanner scans given range in one-millionth time of piezoelectric scanner - tens to hundreds of nanoseconds per interferometer order. Also reducing size of interferometer.
Electro-optical characterization of GaAs solar cells
NASA Technical Reports Server (NTRS)
Olsen, Larry C.; Dunham, Glen; Addis, F. W.; Huber, Dan; Daling, Dave
The electro-optical characterization of gallium arsenide p/n solar cells is discussed. The objective is to identify and understand basic mechanisms which limit the performance of high efficiency gallium arsenide solar cells. The approach involves conducting photoresponse and temperature dependent current-voltage measurements, and interpretation of the data in terms of theory to determine key device parameters. Depth concentration profiles are also utilized in formulating a model to explain device performance.
A final look at LDEF electro-optic systems components
NASA Technical Reports Server (NTRS)
Blue, M. D.
Postrecovery characteristics of LDEF electro-optic components from the GTRI tray are compared with their prelaunch characteristics and with the characteristics of similar components from related experiments. Components considered here include lasers, light-emitting diodes, semiconducting radiation detectors and arrays, optical substrates, filters, and mirrors, and specialized coatings. Our understanding of the physical effects resulting from low earth orbit are described, and guidelines and recommendations for component and materials choices are presented.
Visualizing Sound with an Electro-Optical Eardrum
NASA Astrophysics Data System (ADS)
Truncale, Nicholas P.; Graham, Michelle T.
As science educators, one of our important responsibilities is ensuring students possess the proper tools and accommodations to examine phenomena in a laboratory setting. It is our job to innovate methods enabling students with disabilities to participate in all aspects of investigations. This article describes an experimental accommodation allowing a deaf student to determine and plot the sensitivity of an electro-optical eardrum in the sound range of 10-150 Hz.
Magneto-optic and electro-optic modulators
Hutchinson, D.P.; Ma, C.H.; Price, T.R.; Staats, P.A.; Vander Sluis, K.L.
An important aspect of the Faraday rotation diagnostic for tokamak plasma measurements has been the development of suitable polarization modulators for submillimeter wavelengths. The problems are to obtain high optical transmission and fast modulation frequencies. At ORNL we have developed both a magneto-optic and an electro-optic submillimeter-wave modulators. These devices have been operated at modulation frequencies of approximately 100 kHz and both have high transmission.
Medical Image Provessing using Transient Fourier Holography in Bacteriorhodopsin Films
NASA Astrophysics Data System (ADS)
Kothapalli, Sri-Rajasekhar; Wu, Pengfei; Yelleswarapu, Chandra; Devulapalli, Rao
A real-time optical Fourier image processing system is demonstrated for early detection of microcalcifications in screen film as well as digital mammograms. The principle is based on recording and reconstructing the transient photoisomerizative grating formed in the bR film. At first Fourier hologram is recorded by spatially overlapping the Fourier transformed object beam with the reference beam in the bR film. Then the object beam is blocked and the reference beam performs the reconstruction of the recorded Fourier hologram. The optimum of diffraction efficiency occurs when object beam intensity is matched to the reference beam intensity. We exploit this technique to process mammograms in real-time for identification of microcalcifications buried in the soft tissue for early detection of breast cancer. A novel feature of the technique is the ability to transient display of selected spatial frequencies in the reconstructing process which enables the radiologists to study the features of interest in time scale.
Innovative, Inexpensive Etching Technique Developed for Polymer Electro- Optical Structures
NASA Technical Reports Server (NTRS)
Nguyen, Hung D.
Electro-optic, polymer-based integrated optic devices for high-speed communication and computing applications offer potentially significant advantages over conventional inorganic electro-optic crystals. One key area of integrated optical technology--primary processing and fabrication--may particularly benefit from the use of polymer materials. However, as efforts concentrate on the miniaturization of electro-integrated circuit pattern geometries, the ability to etch fine features and smoothly sloped sidewalls is essential to make polymers useful for electro-integrated circuit applications. There are many existing processes available to etch polymer materials, but they all yield nearly vertical sidewalls. Vertical sidewalls are too difficult to reliably cover with a metal layer, and incomplete metalization degrades microwave performance, particularly at high frequency. However, obtaining a very sloped sidewall greatly improves the deposition of metal on the sidewall, leading to low-loss characteristics, which are essential to integrating these devices in highspeed electro-optic modulators. The NASA Lewis Research Center has developed in-house an inexpensive etching technique that uses a photolithography method followed by a simple, wet chemical etching process to etch through polymer layers. In addition to being simpler and inexpensive, this process can be used to fabricate smoothly sloped sidewalls by using a commercial none rodible mask: Spin-On-Glass. A commercial transparent material, Spin-On-Glass, uses processes and equipment similar to that for photoresist techniques.
Electro-optic voltage sensor with Multiple Beam Splitting
Woods, Gregory K.; Renak, Todd W.; Crawford, Thomas M.; Davidson, James R.
A miniature electro-optic voltage sensor system capable of accurate operation at high voltages without use of the dedicated voltage dividing hardware. The invention achieves voltage measurement without significant error contributions from neighboring conductors or environmental perturbations. The invention employs a transmitter, a sensor, a detector, and a signal processor. The transmitter produces a beam of electromagnetic radiation which is routed into the sensor. Within the sensor the beam undergoes the Pockels electro-optic effect. The electro-optic effect produces a modulation of the beam's polarization, which is in turn converted to a pair of independent conversely-amplitude-modulated signals, from which the voltage of the E-field is determined by the signal processor. The use of converse AM signals enables the signal processor to better distinguish signal from noise. The sensor converts the beam by splitting the beam in accordance with the axes of the beam's polarization state (an ellipse) into at least two AM signals. These AM signals are fed into a signal processor and processed to determine the voltage between a ground conductor and the conductor on which voltage is being measured.
Electro-optic voltage sensor with beam splitting
Woods, Gregory K.; Renak, Todd W.; Davidson, James R.; Crawford, Thomas M.
The invention is a miniature electro-optic voltage sensor system capable of accurate operation at high voltages without use of the dedicated voltage dividing hardware typically found in the prior art. The invention achieves voltage measurement without significant error contributions from neighboring conductors or environmental perturbations. The invention employs a transmitter, a sensor, a detector, and a signal processor. The transmitter produces a beam of electromagnetic radiation which is routed into the sensor. Within the sensor the beam undergoes the Pockels electro-optic effect. The electro-optic effect produces a modulation of the beam's polarization, which is in turn converted to a pair of independent conversely-amplitude-modulated signals, from which the voltage of the E-field is determined by the signal processor. The use of converse AM signals enables the signal processor to better distinguish signal from noise. The sensor converts the beam by splitting the beam in accordance with the axes of the beam's polarization state (an ellipse) into at least two AM signals. These AM signals are fed into a signal processor and processed to determine the voltage between a ground conductor and the conductor on which voltage is being measured.
Comparative analysis of imaging configurations and objectives for Fourier microscopy.
Kurvits, Jonathan A; Jiang, Mingming; Zia, Rashid
Fourier microscopy is becoming an increasingly important tool for the analysis of optical nanostructures and quantum emitters. However, achieving quantitative Fourier space measurements requires a thorough understanding of the impact of aberrations introduced by optical microscopes that have been optimized for conventional real-space imaging. Here we present a detailed framework for analyzing the performance of microscope objectives for several common Fourier imaging configurations. To this end, we model objectives from Nikon, Olympus, and Zeiss using parameters that were inferred from patent literature and confirmed, where possible, by physical disassembly. We then examine the aberrations most relevant to Fourier microscopy, including the alignment tolerances of apodization factors for different objective classes, the effect of magnification on the modulation transfer function, and vignetting-induced reductions of the effective numerical aperture for wide-field measurements. Based on this analysis, we identify an optimal objective class and imaging configuration for Fourier microscopy. In addition, the Zemax files for the objectives and setups used in this analysis have been made publicly available as a resource for future studies. PMID:26560923
PREFACE: Colloidal and molecular electro-optics Colloidal and molecular electro-optics
NASA Astrophysics Data System (ADS)
Palberg, Thomas; Löwen, Hartmut
The Kerr effect, also known as the quadratic electro-optic effect, was discovered more than a hundred years ago by John Kerr, a Scottish physicist [1]. It describes the change in the refractive index of a material in response to an applied electric field. Around 1950 its application swayed from simple to complex fluids. A strong contribution was made through a number of seminal papers by the French polymer scientist H Benoit [2-4]. These and others initiated wide interest from researchers working on macromolecular solutions or colloidal dispersions. Experimental activities were further boosted by the advent of the laser and theoretical approaches strongly drew from growing computer power. Use of AC or pulsed field techniques, as well as of inhomogeneous fields, including laser tweezers, studies of electrophoretic, dielectrophoretic, electro-osmotic and other types of motion by advanced optical methods and combinations with other external fields have had the greatest impact on our understanding of the electric field induced optical properties of soft matter systems. Today the field has matured and its techniques are broadly employed as versatile tools with applications ranging from biological systems to electronic ink. Fundamental interest still continues but more and more side branches have evolved fruitfully. This collection of papers was, therefore, brought together to take a fresh look at this traditional field. Further, we are to celebrate 35 years of a successful conference series, ELOPTO, with the last one held at Waldthausen Castle hosted by the Johannes Gutenberg University, MainzNote1 and the DFG Collaborative Research Centre TR6 'Physics of colloidal dispersions in external fields'Note2. In this issue we have collected the articles of some of the leading experts in the area, well garnished with novel approaches and clever ideas by younger colleagues. With our selection we hope to cover a representative spectrum of the ongoing research, catch the most
Stereo Electro-optical Tracking System (SETS)
NASA Technical Reports Server (NTRS)
Koenig, E. W.
The SETS is a remote, non-contacting, high-accuracy tracking system for the measurement of deflection of models in the National Transonic Facility at Langley Research Center. The system consists of four electronically scanned image dissector trackers which locate the position of Light Emitting Diodes embedded in the wing or body of aircraft models. Target location data is recorded on magnetic tape for later 3-D processing. Up to 63 targets per model may be tracked at typical rates of 1280 targets per second and to precision of 0.02mm at the target under the cold (-193 C) environment of the NTF tunnel.
LLNL electro-optical mine detection program
Anderson, C.; Aimonetti, W.; Barth, M.; Buhl, M.; Bull, N.; Carter, M.; Clark, G.; Fields, D.; Fulkerson, S.; Kane, R.
Under funding from the Advanced Research Projects Agency (ARPA) and the US Marine Corps (USMC), Lawrence Livermore National Laboratory (LLNL) has directed a program aimed at improving detection capabilities against buried mines and munitions. The program has provided a national test facility for buried mines in arid environments, compiled and distributed an extensive data base of infrared (IR), ground penetrating radar (GPR), and other measurements made at that site, served as a host for other organizations wishing to make measurements, made considerable progress in the use of ground penetrating radar for mine detection, and worked on the difficult problem of sensor fusion as applied to buried mine detection. While the majority of our effort has been concentrated on the buried mine problem, LLNL has worked with the U.S.M.C. on surface mine problems as well, providing data and analysis to support the COBRA (Coastal Battlefield Reconnaissance and Analysis) program. The original aim of the experimental aspect of the program was the utilization of multiband infrared approaches for the detection of buried mines. Later the work was extended to a multisensor investigation, including sensors other than infrared imagers. After an early series of measurements, it was determined that further progress would require a larger test facility in a natural environment, so the Buried Object Test Facility (BOTF) was constructed at the Nevada Test Site. After extensive testing, with sensors spanning the electromagnetic spectrum from the near ultraviolet to radio frequencies, possible paths for improvement were: improved spatial resolution providing better ground texture discrimination; analysis which involves more complicated spatial queueing and filtering; additional IR bands using imaging spectroscopy; the use of additional sensors other than IR and the use of data fusion techniques with multi-sensor data; and utilizing time dependent observables like temperature.
Novel fringe scanning/Fourier transform method of synthetic imaging
Crawford, T.M.; Albano, R.K.
We have developed a one-dimensional theory and a computer model for synthetically imaging scenes using a novel fringe scanning/Fourier transform technique. Our method probes a scene using two interfering beams of slightly different frequency. These beams form a moving fringe pattern which scans the scene and resonates with any spatial frequency components having the same spatial frequency as the scanning fringe pattern. A simple, non-imaging detector above the scene observes any scattered radiation from the scene falling onto it. If a resonance occurs between the scanning fringe pattern and the scene, then the scattered radiation will be modulated at the difference frequency between the two probing beams. By changing the spatial period of the fringe pattern and then measuring the amplitude and phase of the modulated radiation that is scattered from the scene, the Fourier amplitudes and phases of the different spatial frequency components making up the scene can be measured. A synthetic image of the scene being probed can be generated from this Fourier amplitude and phase data by taking the inverse Fourier transform of this information. This technique could be used to image objects using light, ultrasonic, or other electromagnetic or acoustic waves.
Grid-Independent Compressive Imaging and Fourier Phase Retrieval
ERIC Educational Resources Information Center
Liao, Wenjing
This dissertation is composed of two parts. In the first part techniques of band exclusion(BE) and local optimization(LO) are proposed to solve linear continuum inverse problems independently of the grid spacing. The second part is devoted to the Fourier phase retrieval problem. Many situations in optics, medical imaging and signal processing call…
Visible Imaging Fourier Transform Spectrometer: Design and Calibration
Wishnow, E H; Wurtz, R; Blais-Ouellette, S; Cook, K H; Carr, D; Lewis, I; Grandmont, F; Stubbs, C W
We present details of the design, operation and calibration of an astronomical visible-band imaging Fourier transform spectrometer (IFTS). This type of instrument produces a spectrum for every pixel in the field of view where the spectral resolution is flexible. The instrument is a dual-input/dual-output Michelson interferometer coupled to the 3.5 meter telescope at the Apache Point Observatory. Imaging performance and interferograms and spectra from calibration sources and standard stars are discussed.
Errors of fourier chemical-shift imaging and their corrections
NASA Astrophysics Data System (ADS)
Wang, Zhiyue; Bolinger, Lizann; Subramanian, V. Harihara; Leigh, John S.
From a finite and discrete Fourier transform point of view, we discuss the sources of localization errors in Fourier chemical-shift imaging, and demonstrate them explicitly by computer simulations for simple cases. Errors arise from intravoxel dephasing and the intravoxel asymmetry. The spectral leakage due to intravoxel dephasing is roughly 6-8% from one voxel to one of its nearest neighbors. Neighbors further away are influenced less significantly. The loss of localization due to intravoxel asymmetry effect is also severe. Fortunately, these errors can be corrected under certain conditions. The method for correcting the errors by postprocessing the data is described.
Electro-optic crystal mosaics for the generation of terahertz radiation
Carrig, Timothy J.; Taylor, Antoinette J.; Stewart, Kevin R.
Apparatus for the generation of high energy terahertz radiation is presented and comprises laser means effective to produce subpicosecond optical pulses and a mosaic comprising a plurality of planar electro-optic crystals fastened together edge to edge in the form of a grid. The electro-optic crystals are in optical communication with the subpicosecond optical pulses, and behave as a single large electro-optic crystal, producing high energy terahertz radiation by way of optical rectification.
Electro-optic crystal mosaics for the generation of terahertz radiation
Carrig, T.J.; Taylor, A.J.; Stewart, K.R.
Apparatus for the generation of high energy terahertz radiation is presented and comprises laser means effective to produce subpicosecond optical pulses and a mosaic comprising a plurality of planar electro-optic crystals fastened together edge to edge in the form of a grid. The electro-optic crystals are in optical communication with the subpicosecond optical pulses, and behave as a single large electro-optic crystal, producing high energy terahertz radiation by way of optical rectification. 5 figs.
MTF measurements on real time for performance analysis of electro-optical systems
NASA Astrophysics Data System (ADS)
Stuchi, Jose Augusto; Signoreto Barbarini, Elisa; Vieira, Flavio Pascoal; dos Santos, Daniel, Jr.; Stefani, Mário Antonio; Yasuoka, Fatima Maria Mitsue; Castro Neto, Jarbas C.; Linhari Rodrigues, Evandro Luis
The need of methods and tools that assist in determining the performance of optical systems is actually increasing. One of the most used methods to perform analysis of optical systems is to measure the Modulation Transfer Function (MTF). The MTF represents a direct and quantitative verification of the image quality. This paper presents the implementation of the software, in order to calculate the MTF of electro-optical systems. The software was used for calculating the MTF of Digital Fundus Camera, Thermal Imager and Ophthalmologic Surgery Microscope. The MTF information aids the analysis of alignment and measurement of optical quality, and also defines the limit resolution of optical systems. The results obtained with the Fundus Camera and Thermal Imager was compared with the theoretical values. For the Microscope, the results were compared with MTF measured of Microscope Zeiss model, which is the quality standard of ophthalmological microscope.
Synthesis of electro-optic modulators for amplitude modulation of light
NASA Technical Reports Server (NTRS)
Ammann, E. O.; Yarborough, J. M.
Electro-optical modulator realizes voltage transfer function in synthesizing birefringent networks. Choice of the voltage transfer function is important, the most satisfactory optimizes the modulator property.
Introduction into service of mature pushbroom electro-optic sensors
NASA Astrophysics Data System (ADS)
Brownie, Ralph S.
Pushbroom Electro-Optic sensors have been developed and brought into full production, entering service in year 2000 on RAF Jaguar and Belgian Air Force F-16. The use of fiber- optic gyroscopes, closely coupled to the focal plane electronics, permits correction of all motion effects and provides practical high quality, stereo imagery at high V/H ratios. This paper describes technical features and samples of imagery from a scalable range of sensors incorporating focal lengths from 38mm to 900mm and operating throughout the full flight envelope of modern fighter aircraft.
Nanosecond Electro-Optic Switching of a Liquid Crystal
NASA Astrophysics Data System (ADS)
Borshch, Volodymyr; Shiyanovskii, Sergij V.; Lavrentovich, Oleg D.
Electrically induced reorientation of nematic liquid crystal (NLC) molecules caused by dielectric anisotropy of the material is a fundamental phenomenon widely used in modern technologies. Its Achilles heel is a slow (millisecond) relaxation from the field-on to the field-off state. We present an electro-optic effect in an NLC with a response time of about 30 ns to both the field-on and field-off switching. This effect is caused by the electric field induced modification of the order parameters and does not require reorientation of the optic axis (director).
Electro-optic analyzer of angular momentum hyperentanglement.
Wu, Ziwen; Chen, Lixiang
Characterizing a high-dimensional entanglement is fundamental in quantum information applications. Here, we propose a theoretical scheme to analyze and characterize the angular momentum hyperentanglement that two photons are entangled simultaneously in spin and orbital angular momentum. Based on the electro-optic sampling with a proposed hyper-entanglement analyzer and the simple matrix operation using Cramer rule, our simulations show that it is possible to retrieve effectively both the information about the degree of polarization entanglement and the spiral spectrum of high-dimensional orbital angular momentum entanglement. PMID:26911530
Electro-optic analyzer of angular momentum hyperentanglement
NASA Astrophysics Data System (ADS)
Wu, Ziwen; Chen, Lixiang
Characterizing a high-dimensional entanglement is fundamental in quantum information applications. Here, we propose a theoretical scheme to analyze and characterize the angular momentum hyperentanglement that two photons are entangled simultaneously in spin and orbital angular momentum. Based on the electro-optic sampling with a proposed hyper-entanglement analyzer and the simple matrix operation using Cramer rule, our simulations show that it is possible to retrieve effectively both the information about the degree of polarization entanglement and the spiral spectrum of high-dimensional orbital angular momentum entanglement.
Wavelength-tunable laser based on electro-optic effect
NASA Astrophysics Data System (ADS)
Wu, Pengfei; Tang, Suning
Currently available wavelength-tunable lasers have technical difficulty in combining high-speed, continuous and wide wavelength tunability with high output power. We demonstrated a high-speed wavelength-tunable laser based on a fast electro-optic effect. We observed that the wavelength-swept speed exceeds 107 nm/s at center wavelength of 1550 nm with continuous wavelength tunability. Moreover, the maximum output power is over 100 mW and the wavelength tuning range is near 100 nm with a full width at half maximum of less than 0.5 nm.
Electro-optic analyzer of angular momentum hyperentanglement
Wu, Ziwen; Chen, Lixiang
Characterizing a high-dimensional entanglement is fundamental in quantum information applications. Here, we propose a theoretical scheme to analyze and characterize the angular momentum hyperentanglement that two photons are entangled simultaneously in spin and orbital angular momentum. Based on the electro-optic sampling with a proposed hyper-entanglement analyzer and the simple matrix operation using Cramer rule, our simulations show that it is possible to retrieve effectively both the information about the degree of polarization entanglement and the spiral spectrum of high-dimensional orbital angular momentum entanglement. PMID:26911530
Electro optical tuning of Tamm-plasmon exciton-polaritons
Gessler, J.; Baumann, V.; Emmerling, M.; Amthor, M.; Winkler, K.; Schneider, C.; Kamp, M.; Höfling, S.
We report on electro optical tuning of the emission from GaAs quantum wells resonantly coupled to a Tamm-plasmon mode in a hybrid metal/dielectric structure. The structures were studied via momentum resolved photoluminescence and photoreflectance spectroscopy, and the surface metal layer was used as a top gate, which allowed for a precise tuning of the quantum well emission via the quantum confined Stark effect. By tuning the resonance, we were able to observe the characteristic anticrossing behavior of a polaritonic emission in the strong light-matter coupling regime, yielding a Rabi splitting of (9.2 ± 0.2) meV.
Electro-Optical Modulator Bias Control Using Bipolar Pulses
NASA Technical Reports Server (NTRS)
Farr, William; Kovalik, Joseph
An improved method has been devised for controlling the DC bias applied to an electro-optical crystal that is part of a Mach-Zehnder modulator that generates low-duty-cycle optical pulses for a pulse-position modulation (PPM) optical data-communication system. In such a system, it is desirable to minimize the transmission of light during the intervals between pulses, and for this purpose, it is necessary to maximize the extinction ratio of the modulator (the ratio between the power transmitted during an "on" period and the power transmitted during an "off" period). The present method is related to prior dither error feedback methods, but unlike in those methods, there is no need for an auxiliary modulation subsystem to generate a dithering signal. Instead, as described below, dither is effected through alternation of the polarity of the modulation signal. The upper part of Figure 1 schematically depicts a Mach-Zehnder modulator. The signal applied to the electro-optical crystal consists of a radio-frequency modulating pulse signal, VRF, superimposed on a DC bias Vbias. Maximum extinction occurs during the off (VRF = 0) period if Vbias is set at a value that makes the two optical paths differ by an odd integer multiple of a half wavelength so that the beams traveling along the two paths interfere destructively at the output beam splitter. Assuming that the modulating pulse signal VRF has a rectangular waveform, maximum transmission occurs during the "on" period if the amplitude of VRF is set to a value, V , that shifts the length of the affected optical path by a half wavelength so that now the two beams interfere constructively at the output beam splitter. The modulating pulse signal is AC-coupled from an amplifier to the electro-optical crystal. Sometimes, two successive pulses occur so close in time that the operating point of the amplifier drifts, one result being that there is not enough time for the signal level to return to ground between pulses. Also, the
Track Initiation for Electro-Optical Tracking of Space Objects
NASA Astrophysics Data System (ADS)
Xu, Z. W.; Wang, X.
Aimed at the track initiation for the electro-optical tracking of space objects, and based on modified Hough transformation, a track initiation algorithm without prior information is proposed to realize the fully robotic identification and tracking of moving objects. The method is valid for the tracking of multi-target as well as with a non-continuous sequence. Simulation shows that the method is effective and applicable for operational usage, and is especially good for the search and discovery of new objects.
Radiation resistance of electro-optic polymer-based modulators
Taylor, Edward W.; Nichter, James E.; Nash, Fazio D.; Haas, Franz; Szep, Attila A.; Michalak, Richard J.; Flusche, Brian M.; Cook, Paul R.; McEwen, Tom A.; McKeon, Brian F.; Payson, Paul M.; Brost, George A.; Pirich, Andrew R.; Castaneda, Carlos; Tsap, Boris; Fetterman, Harold R.
Mach-Zehnder interferometric electro-optic polymer modulators composed of highly nonlinear phenyltetraene bridge-type chromophores within an amorphous polycarbonate host matrix were investigated for their resistance to gamma rays and 25.6 MeV protons. No device failures were observed and the majority of irradiated modulators exhibited decreases in half-wave voltage and optical insertion losses compared to nonirradiated control samples undergoing aging processes. Irradiated device responses were attributed to scission, cross-linking, and free volume processes. The data suggests that strongly poled devices are less likely to de-pole under the influence of ionizing radiation.
Birefringent Fourier transform imaging spectrometer with a rotating retroreflector.
Bai, Caixun; Li, Jianxin; Shen, Yan; Zhou, Jianqiang
A birefringent Fourier transform imaging spectrometer with a new lateral shearing interferometer is presented. The interferometer includes a Wollaston prism and a retroreflector. It splits an incident light beam into two shearing parallel parts to obtain interference fringe patterns of an imaging target, which is well established as an aid in reducing problems associated with optical alignment and manufacturing precision. Continuously rotating the retroreflector enables the spectrometer to acquire two-dimensional spectral images without spatial scanning. This technology, with a high work efficiency and low complexity, is inherently compact and robust. The effectiveness of the proposed method is demonstrated by the experimental results. PMID:27472640
Astronomical imaging Fourier spectroscopy at far-infrared wavelengths
NASA Astrophysics Data System (ADS)
Naylor, David A.; Gom, Brad G.; van der Wiel, Matthijs H. D.; Makiwa, Gibion
The principles and practice of astronomical imaging Fourier transform spectroscopy (FTS) at far-infrared wavelengths are described. The MachâZehnder (MZ) interferometer design has been widely adopted for current and future imaging FTS instruments; we compare this design with two other common interferometer formats. Examples of three instruments based on the MZ design are presented. The techniques for retrieving astrophysical parameters from the measured spectra are discussed using calibration data obtained with the HerschelâSPIRE instrument. The paper concludes with an example of imaging spectroscopy obtained with the SPIRE FTS instrument.
Experimental results from an airborne static Fourier transform imaging spectrometer.
Ferrec, Yann; Taboury, Jean; Sauer, Hervé; Chavel, Pierre; Fournet, Pierre; Coudrain, Christophe; Deschamps, Joël; Primot, Jérôme
A high étendue static Fourier transform spectral imager has been developed for airborne use. This imaging spectrometer, based on a Michelson interferometer with rooftop mirrors, is compact and robust and benefits from a high collection efficiency. Experimental airborne images were acquired in the visible domain. The processing chain to convert raw images to hyperspectral data is described, and airborne spectral images are presented. These experimental results show that the spectral resolution is close to the one expected, but also that the signal to noise ratio is limited by various phenomena (jitter, elevation fluctuations, and one parasitic image). We discuss the origin of those limitations and suggest solutions to circumvent them. PMID:22015418
Gradient-based image recovery methods from incomplete Fourier measurements.
Patel, Vishal M; Maleh, Ray; Gilbert, Anna C; Chellappa, Rama
A major problem in imaging applications such as magnetic resonance imaging and synthetic aperture radar is the task of trying to reconstruct an image with the smallest possible set of Fourier samples, every single one of which has a potential time and/or power cost. The theory of compressive sensing (CS) points to ways of exploiting inherent sparsity in such images in order to achieve accurate recovery using sub-Nyquist sampling schemes. Traditional CS approaches to this problem consist of solving total-variation (TV) minimization programs with Fourier measurement constraints or other variations thereof. This paper takes a different approach. Since the horizontal and vertical differences of a medical image are each more sparse or compressible than the corresponding TV image, CS methods will be more successful in recovering these differences individually. We develop an algorithm called GradientRec that uses a CS algorithm to recover the horizontal and vertical gradients and then estimates the original image from these gradients. We present two methods of solving the latter inverse problem, i.e., one based on least-square optimization and the other based on a generalized Poisson solver. After a thorough derivation of our complete algorithm, we present the results of various experiments that compare the effectiveness of the proposed method against other leading methods. PMID:21690011
Fourier transform digital holographic adaptive optics imaging system
Liu, Changgeng; Yu, Xiao; Kim, Myung K.
A Fourier transform digital holographic adaptive optics imaging system and its basic principles are proposed. The CCD is put at the exact Fourier transform plane of the pupil of the eye lens. The spherical curvature introduced by the optics except the eye lens itself is eliminated. The CCD is also at image plane of the target. The point-spread function of the system is directly recorded, making it easier to determine the correct guide-star hologram. Also, the light signal will be stronger at the CCD, especially for phase-aberration sensing. Numerical propagation is avoided. The sensor aperture has nothing to do with the resolution and the possibility of using low coherence or incoherent illumination is opened. The system becomes more efficient and flexible. Although it is intended for ophthalmic use, it also shows potential application in microscopy. The robustness and feasibility of this compact system are demonstrated by simulations and experiments using scattering objects. PMID:23262541
Optimal color image restoration: Wiener filter and quaternion Fourier transform
NASA Astrophysics Data System (ADS)
Grigoryan, Artyom M.; Agaian, Sos S.
In this paper, we consider the model of quaternion signal degradation when the signal is convoluted and an additive noise is added. The classical model of such a model leads to the solution of the optimal Wiener filter, where the optimality with respect to the mean square error. The characteristic of this filter can be found in the frequency domain by using the Fourier transform. For quaternion signals, the inverse problem is complicated by the fact that the quaternion arithmetic is not commutative. The quaternion Fourier transform does not map the convolution to the operation of multiplication. In this paper, we analyze the linear model of the signal and image degradation with an additive independent noise and the optimal filtration of the signal and images in the frequency domain and in the quaternion space.
Electron Bunch Shape Measurements Using Electro-optical Spectral Decoding
NASA Astrophysics Data System (ADS)
Borysenko, A.; Hiller, N.; Müller, A.-S.; Steffen, B.; Peier, P.; Ivanisenko, Y.; Ischebeck, R.; Schlott, V.
Longitudinal diagnostics of the electron bunch shapes play a crucial role in the operation of linac-based light sources. Electro-optical techniques allow us to measure the longitudinal electron bunch profiles non-destructively on a shot-by-shot basis. Here we present results from measurements of electron bunches with a length of 200-900 fs rms at the Swiss FEL Injector Test Facility. All the measurements were done using an Yb-doped fibre laser system (with a central wavelength of a 1050 nm) and a GaP crystal. The technique of electro-optical spectral decoding (EOSD) was applied and showed great capabilities to measure bunch shapes down to around 370 fs rms. Measurements were performed for different electron energies to study the expected distortions of the measured bunch profile due to the energy-dependent widening of the electric field, which plays a role for low beam energies below and around 40 MeV. The studies provide valuable input for the design of the EOSD monitors for the compact linear accelerator FLUTE that is currently under commissioning at the Karslruhe Institute of Technology (KIT).
Relaxation Times of Microemulsion Systems From Electro-Optical Measurements
NASA Astrophysics Data System (ADS)
Edwards, Matthew
Relaxation Times of Microemulsion Systems from Electro-Optical Measurements Matthew Edwards (Spelman College) Relaxation measurements, as determined from electro-optically induced birefringence, have been made on ternary microemulsion systems of AOT, water, and octane. Loci of 22 samples, representing displacements along the 90oil concentration line in the three-component phase diagram, were prepared having weight fractions ranging from 0to AOT+water to 60times, at room temperature, changed by more than an order of magnitude in this phase diagram displacement, going from 2.55x10(-7)at 0The methodology for determing each sample's relaxation time was to fit the raw data of polarized - transmitted laser intensity as a function of time, as generated from using the standard Kerr effect. The raw data sample sets were fitted to within 8exponentially decaying function. The single exponential decay mechanism that is thought to be "effective rotational relaxation." This supports our earlier measurements (1) which indicate clustering of composite droplets within the microemulsion samples following the onset of the applied electric field. 1. Edwards, M.E. et, Physical Review E, 57, No. 797 (1998)
Electro-optical effects in hybrid aligned flexoelectric nematic layers
NASA Astrophysics Data System (ADS)
Derfel, G.; Buczkowska, M.
Liquid crystal cells with hybrid boundary anchoring, filled with nematic possessing flexoelectric properties, and subjected to external electric field, were studied numerically in order to find the influence of flexoelectricity on their behavior. Such layers may adopt three kinds of director structures: uniform planar, uniform homeotropic, and non-uniform which is intermediate between the former two. Stability of these structures depends on flexoelectric coefficients, anchoring strengths, thickness of the layer, dielectric anisotropy, and elastic constants. Changes of bias voltage cause transitions between them, which lead to electro-optical effects if the layers are placed between crossed polarizers. Three cases of transitions were considered: (i) transition between bright planar and dark non-uniform states, (ii) between dark planar and bright non-uniform states, and (iii) between dark homeotropic and bright non-uniform states. The director distributions in various states corresponding to various grey levels were calculated, and the electro-optic characteristics were obtained. The dynamics of the transitions between dark, bright, and intermediate states was determined taking into account the backflow effect. It was found that the transitions are faster when the nematic is devoid of flexoelectric properties.
Development of a stable electro-optical modulator
NASA Technical Reports Server (NTRS)
Abushagur, Mustafa A. G.
The activity of the sun can be studied through the measurement of its magnetic field. The measurement of the polarization state of the sunlight in a narrow spectral bandwidth can be related to the magnetic fields strengths and directions over the active sunspots. Measuring the polarization state can be done using the vector magnetograph. The essential component of the vector magnetograph is the polarization modulators. Electro-optical modulators are used as dynamic retarders. KDP (potassium dideuterium phosphate) crystals provide variable retardation which can be controlled by the applied voltage. KDP's have a high contrast ratio but suffer some problems; they require a high voltage and have a limited modulation lifetime. The KDP modulator forms the heart of the polarimeter assembly which is used for carrying out accurate measurements of linear polarization of the sun. It is therefore important to study the optical and electrical behavior of the KDP crystals so that the ultimate goal of making stable electro-optical modulators in the laboratory is achieved. A number of activities were performed in coating and testing the KDP crystals. A summary of these activities is given.
Automatic building detection and 3D shape recovery from single monocular electro-optic imagery
NASA Astrophysics Data System (ADS)
Lavigne, Daniel A.; Saeedi, Parvaneh; Dlugan, Andrew; Goldstein, Norman; Zwick, Harold
The extraction of 3D building geometric information from high-resolution electro-optical imagery is becoming a key element in numerous geospatial applications. Indeed, producing 3D urban models is a requirement for a variety of applications such as spatial analysis of urban design, military simulation, and site monitoring of a particular geographic location. However, almost all operational approaches developed over the years for 3D building reconstruction are semiautomated ones, where a skilled human operator is involved in the 3D geometry modeling of building instances, which results in a time-consuming process. Furthermore, such approaches usually require stereo image pairs, image sequences, or laser scanning of a specific geographic location to extract the 3D models from the imagery. Finally, with current techniques, the 3D geometric modeling phase may be characterized by the extraction of 3D building models with a low accuracy level. This paper describes the Automatic Building Detection (ABD) system and embedded algorithms currently under development. The ABD system provides a framework for the automatic detection of buildings and the recovery of 3D geometric models from single monocular electro-optic imagery. The system is designed in order to cope with multi-sensor imaging of arbitrary viewpoint variations, clutter, and occlusion. Preliminary results on monocular airborne and spaceborne images are provided. Accuracy assessment of detected buildings and extracted 3D building models from single airborne and spaceborne monocular imagery of real scenes are also addressed. Embedded algorithms are evaluated for their robustness to deal with relatively dense and complicated urban environments.
Denoising and deblurring of Fourier transform infrared spectroscopic imaging data
NASA Astrophysics Data System (ADS)
Nguyen, Tan H.; Reddy, Rohith K.; Walsh, Michael J.; Schulmerich, Matthew; Popescu, Gabriel; Do, Minh N.; Bhargava, Rohit
Fourier transform infrared (FT-IR) spectroscopic imaging is a powerful tool to obtain chemical information from images of heterogeneous, chemically diverse samples. Significant advances in instrumentation and data processing in the recent past have led to improved instrument design and relatively widespread use of FT-IR imaging, in a variety of systems ranging from biomedical tissue to polymer composites. Various techniques for improving signal to noise ratio (SNR), data collection time and spatial resolution have been proposed previously. In this paper we present an integrated framework that addresses all these factors comprehensively. We utilize the low-rank nature of the data and model the instrument point spread function to denoise data, and then simultaneously deblurr and estimate unknown information from images, using a Bayesian variational approach. We show that more spatial detail and improved image quality can be obtained using the proposed framework. The proposed technique is validated through experiments on a standard USAF target and on prostate tissue specimens.
Wideband electromagnetic scattering program. Fourier-based radar imaging techniques
NASA Astrophysics Data System (ADS)
Chan, B. L.; Young, J. D.; Rudduck, R. C.
This report describes the implementation of Fourier based radar imaging algorithms in a computer program. In particular, the algorithms are derived for wide bandwidth and for specific geometries. These geometries are often measured by radar cross section measurement systems such as compact ranges and near field linear synthetic aperture radar systems. The limitations of different implementations of the algorithms are presented. Imaging results from radar measurements are also presented for an F-4 fighter aircraft, an M35 truck (1/16 scale model), and a forest.
A novel electro-optical pump-probe system for bioelectromagnetic investigations
NASA Astrophysics Data System (ADS)
De Angelis, Annalisa; Couderc, Vincent; Leproux, Philippe; Labruyère, Alexis; Tonello, Alessandro; El Amari, Saad; Arnaud-Cormos, Delia; Leveque, Philippe
In the area of bioelectromagnetic studies there is a growing interest to understand the mechanisms leading to nanosecond electric fields induced electroporation. Real-time imaging techniques at molecular level could probably bring further advances on how electric fields interact with living cells. However the investigations are limited by the present-day lack of these kinds of advanced instrumentations. In this context, we present an innovative electro-optical pump-probe system. The aim of our project is to provide a performing and compact device for electrical stimulation and multiplex Coherent anti-Stokes Raman Scattering (M-CARS) imaging of biological cells at once. The system consists of a 1064 nm sub-nanosecond laser source providing both a monochromatic pump and a polychromatic Stokes optical beam used in a CARS process, as well as the trigger beam for the optoelectronic switching-based electrical pulse generator. The polychromatic Stokes beam (from 600 to 1700 nm) results from a supercontinuum generation in a photonic crystal fiber (PCF). A detailed spectro-temporal characterization of such a broadband spectrum shows the impact of the nonlinear propagation in the fiber on the Stokes wave. Despite the temporal distortions observable on Stokes pulse profiles, their spectral synchronization with the pump pulse remains possible and efficient in the interesting region between 1100 nm and 1700 nm. The electrical stimulation device consists of a customized generator combining microstrip-line technology and laser-triggered photoconductive semiconductor switches. Our experimental characterization highlights the capability for such a generator to control the main pulse parameters (profile, amplitude and duration) and to be easily synchronized with the imaging system. We finally test and calibrate the system by means of a KDP crystal. The preliminary results suggest that this electro-optical system provides a suitable tool for real-time investigation of
Imaging Fourier Transform Spectroscopy from a Space Based Platform -- The Herschel/SPIRE Fourier Transform Spectrometer
NASA Astrophysics Data System (ADS)
Spencer, Locke Dean
The Herschel Space Observatory (Herschel), a flagship mission of the European Space Agency (ESA), is comprised of three cryogenically cooled instruments commissioned to explore the far-infrared/submillimetre universe. Herschel's remote orbit at the second Lagrangian point (L2) of the Sun-Earth system, and its cryogenic payload, impose a need for thorough instrument characterization and rigorous testing as there will be no possibility for any servicing after launch. The Spectral and Photometric Imaging Receiver (SPIRE) is one of the instrument payloads aboard Herschel and consists of a three band imaging photometer and a two band imaging spectrometer. The imaging spectrometer on SPIRE consists of a Mach-Zehnder (MZ)-Fourier transform spectrometer (FTS) coupled with bolometric detector arrays to form an imaging FTS (IFTS). This thesis presents experiments conducted to verify the performance of an IFTS system from a space based platform, Le. the use of the SPIRE IFTS within the Herschel space observatory. Prior to launch, the SPIRE instrument has undergone a series of performance verification tests conducted at the Rutherford Appleton Laboratory (RAL) near Oxford, UK. Canada is involved in the SPIRE project through provision of instrument development hardware and software, mission flight software, and support personnel. Through this thesis project I have been stationed at RAL for a period spanning fifteen months to participate in the development, performance verification, and characterization of both the SPIRE FTS and photometer instruments. This thesis discusses Fourier transform spectroscopy and related FTS data processing (Chapter 2). Detailed discussions are included on the spectral phase related to the FTS beamsplitter (Chapter 3), the imaging aspects of the SPIRE IFTS instrument (Chapter 4), and the noise characteristics of the SPIRE bolometer detector arrays as measured using the SPIRE IFTS (Chapter 5). This thesis presents results from experiments performed
Electro-optic study of PZT ferroelectric ceramics using modulation of reflected light
NASA Astrophysics Data System (ADS)
Kniazkov, A. V.
Electro-optic coefficients of variations in the refractive index of PZT and PLZT ceramic materials induced by ac electric field are estimated using modulation of reflected light. The electro-optic coefficients of PLZT ceramics measured with the aid of conventional birefringence using the phase shift of transmitted radiation and the proposed method of birefringence using the modulation of reflected light are compared.
Electro-optic contribution to field-induced Raman scattering in alkali halides
Subbaswamy, K.R.; Mahan, G.D.
The electro-optic contribution to the field-induced first-order Raman scattering cross section in alkali halide crystals is calculated using measured values for hyperpolarizabilities. The electro-optic contribution is much larger than the previously reported atomic displacement contribution. The results cast some doubt on the accuracy of the reported hyperpolarizability values.
High-resolution lensless Fourier transform holography for microstructure imaging
NASA Astrophysics Data System (ADS)
Zhao, Jie; Wang, Dayong; Wang, Huaying; Xie, Jianjun
Digital holography combines the advantages of the optical holography and the computers. It can implement an all-digital processing and has the quasi real-time property. With lensless Fourier transform recording architecture, the limited bandwidth of CCD camera can be utilized sufficiently, and the sampling theorem is satisfied easily. Therefore, high-resolution can be achieved. So it is preferred in the microstructure imaging. In the paper, based on the Fresnel diffraction theory and the off-axis lensless Fourier transform recording architecture, the experimental optimization and correspondingly the digital reconstruction was investigated. Also, the lateral resolution of the reconstructed image was analyzed and improved by the proposed techniques. When the USAF test target was imaged without any pre-magnification, the lateral resolution of 3.1μm was achieved, which matched the theoretical prediction very well. The key points to achieve high resolution image are to use the smaller object and to arrange the distance between the object and the CCD plane as short as possible. Meanwhile, properly overlapping the reconstructed image with the DC term was helpful to improve the resolution. The noise in the reconstructed image could be reduced greatly by choosing the optical elements precisely and adjusting the beam path finely. The experimental results demonstrated that it is possible for the digital holographic microscopy to produce the high resolution image without the objective pre-magnification. The results also showed that, with a high quality hologram, the special image processing during the reconstruction may be unnecessary to obtain a high quality image.
Optical stress sensor based on electro-optic compensation for photoelastic birefringence in a single crystal
Li Changsheng
An optical stress sensor is proposed by using a single crystal with both electro-optic and photoelastic effects. Different from previous crystal-based stress sensors, the proposed sensor is based on electro-optic compensation for stress-induced birefringence and does not need an additional quarter-wave plate or modulator, because the stress-sensing element is simultaneously used as an electro-optic compensator. Candidate sensing materials include electro-optic crystals of the 3 m symmetry group and all glass with large Kerr coefficients. A primary experiment has demonstrated that the stress-induced birefringence in lithium niobate crystal can be compensated by its electro-optic birefringence. The proposed stress sensor is compact and low cost, and it is possible to achieve closed-loop stress measurement.
An innovative procedure for calibration of strapdown electro-optical sensors onboard unmanned air vehicles.
Fasano, Giancarmine; Accardo, Domenico; Moccia, Antonio; Rispoli, Attilio
This paper presents an innovative method for estimating the attitude of airborne electro-optical cameras with respect to the onboard autonomous navigation unit. The procedure is based on the use of attitude measurements under static conditions taken by an inertial unit and carrier-phase differential Global Positioning System to obtain accurate camera position estimates in the aircraft body reference frame, while image analysis allows line-of-sight unit vectors in the camera based reference frame to be computed. The method has been applied to the alignment of the visible and infrared cameras installed onboard the experimental aircraft of the Italian Aerospace Research Center and adopted for in-flight obstacle detection and collision avoidance. Results show an angular uncertainty on the order of 0.1° (rms). PMID:22315559
An Innovative Procedure for Calibration of Strapdown Electro-Optical Sensors Onboard Unmanned Air Vehicles
Fasano, Giancarmine; Accardo, Domenico; Moccia, Antonio; Rispoli, Attilio
This paper presents an innovative method for estimating the attitude of airborne electro-optical cameras with respect to the onboard autonomous navigation unit. The procedure is based on the use of attitude measurements under static conditions taken by an inertial unit and carrier-phase differential Global Positioning System to obtain accurate camera position estimates in the aircraft body reference frame, while image analysis allows line-of-sight unit vectors in the camera based reference frame to be computed. The method has been applied to the alignment of the visible and infrared cameras installed onboard the experimental aircraft of the Italian Aerospace Research Center and adopted for in-flight obstacle detection and collision avoidance. Results show an angular uncertainty on the order of 0.1° (rms). PMID:22315559
Integrated optics in an electrically scanned imaging Fourier transform spectrometer
NASA Technical Reports Server (NTRS)
Breckinridge, James B. (Inventor); Ocallaghan, Fred G. (Inventor)
An efficient, lightweight and stable, Fourier transform spectrometer was developed. The mechanical slide mechanism needed to create a path difference was eliminated by the use of retro-reflecting mirrors in a monolithic interferometer assembly in which the mirrors are not at 90 degrees to the propagation vector of the radiation, but rather at a small angle. The resulting plane wave fronts create a double-sided inteferogram of the source irradiance distribution which is detected by a charge-coupled device image sensor array. The position of each CCD pixel in the array is an indication of the path difference between the two retro-reflecting mirrors in the monolithic optical structure. The Fourier transform of the signals generated by the image sensor provide the spectral irradiance distribution of the source. For imaging, the interferometer assembly scans the source of irradiation by moving the entire instrument, such as would occur if it was fixedly mounted to a moving platform, i.e., a spacecraft. During scanning, the entrace slot to the monolithic optical structure sends different pixels to corresponding interferograms detected by adjacent columns of pixels of the image sensor.
Imaging Fourier transform spectrometer (IFTS): parametric sensitivity analysis
NASA Astrophysics Data System (ADS)
Keller, Robert A.; Lomheim, Terrence S.
Imaging Fourier transform spectrometers (IFTS) allow for very high spectral resolution hyperspectral imaging while using moderate size 2D focal plane arrays in a staring mode. This is not the case for slit scanning dispersive imaging spectrometers where spectral sampling is related to the focal plane pixel count along the spectral dimension of the 2D focal plane used in such an instrument. This can become a major issue in the longwave infrared (LWIR) where the operability and yield of highly sensitivity arrays (i.e.HgCdTe) of large dimension are generally poor. However using an IFTS introduces its own unique set of issues and tradeoffs. In this paper we develop simplified equations for describing the sensitivity of an IFTS, including the effects of data windowing. These equations provide useful insights into the optical, focal plane and operational design trade space that must be considered when examining IFTS concepts aimed at a specific sensitivity and spectral resolution application. The approach is illustrated by computing the LWIR noise-equivalent spectral radiance (NESR) corresponding to the NASA Geosynchronous Imaging Fourier Transform Spectrometer (GIFTS) concept assuming a proven and reasonable noise-equivalent irradiance (NEI) capability for the focal plane.
Electro-optical and Magneto-optical Sensing Apparatus and Method for Characterizing Free-space Electromagnetic Radiation
Zhang, Xi-Cheng; Riordan, Jenifer Ann; Sun, Feng-Guo
Apparatus and methods for characterizing free-space electromagnetic energy, and in particular, apparatus/method suitable for real-time two-dimensional far-infrared imaging applications are presented. The sensing technique is based on a non-linear coupling between a low-frequency electric (or magnetic) field and a laser beam in an electro-optic (or magnetic-optic) crystal. In addition to a practical counter-propagating sensing technique, a co-linear approach is described which provides longer radiated field-optical beam interaction length, thereby making imaging applications practical.
Electro-optical Neural Platform Integrated with Nanoplasmonic Inhibition Interface.
Yoo, Sangjin; Kim, Raeyoung; Park, Ji-Ho; Nam, Yoonkey
Engineering of neural interfaces with nanomaterials for remote manipulation facilitates the development of platforms for the study and treatment of brain disorders, yet extending their capability to inhibiting the electrical activities of unmodified neurons has been difficult. Here we report the development of an electro-optical neural platform integrated with gold nanorods for simultaneous electrical excitation and readout, and photothermal inhibition of neural activities. A monolayer of gold nanorods was placed at the electrode-neuron interfaces of a microelectrode array for photothermal stimulation of neural activities. This nanoplasmonic interface interacted well with neurons and metal electrodes without affecting the biological and electrical properties. We demonstrated that spontaneous firing of neurons and their signal propagation along the neurites evoked by electrical stimulation were optically inhibited on this neural platform. We believe that our platform could be an alternative to the optogenetic approach and may ultimately be applied to prosthetic devices based on optical neuromodulation. PMID:26960013
Degradation of electro-optic components aboard LDEF
NASA Astrophysics Data System (ADS)
Blue, M. D.
Remeasurement of the properties of a set of electro-optic components exposed to the low-earth environment aboard the Long Duration Exposure Facility (LDEF) indicates that most components survived quite well. Typical components showed some effects related to the space environment unless well protected. The effects were often small but significant. Results for semiconductor infrared detectors, lasers, and LED's, as well as filters, mirrors, and black paints are described. Semiconductor detectors and emitters were scarred but reproduced their original characteristics. Spectral characteristics of multi-layer dielectric filters and mirrors were found to be altered and degraded. Increased absorption in black paints indicates an increase in absorption sites, giving rise to enhanced performance as coatings for baffles and sunscreens.
Electro-optic Laser-Sampled Neutron Detector
J. Kenneth Shultis; Douglas McGregor
A new method of detecting radiation which can allow for long distance measurements is being investigated. The device is primarily for neutrons detection althought it could, in principle, be used for gamma ray detection. The neutron detection medium is a solid, transparent, electro-optical material, such as lithium niobate, lithium tantalite, or barium borate. Crystals of these materials act as optical gates to laser light, allowing light to pass through only when a neutron interaction occurs in the crystal. Typical light detection devices, such as CCD cameras or photomultiplier tubes, can be used to signal when light passes through the crystal. The overall goal of the project is to investigate the feasibility of such devices for the detection of neutron radiation and to quantify their capabilities and limitations.
Electro-optic polymer waveguide grating with fast tuning capability.
Wang, Yi-Ping; Chen, Jian-Ping; Li, Xin-Wan; Zhou, Jun-He; Shen, Hao; Zhang, Xiao-Hong; Ye, Ai-Lun
A novel fast tunable electro-optic (EO) polymer waveguide grating is proposed and designed. Its resonant wavelength can be linearly tuned via the first-order EO effect with a high sensitivity of 6.1 pm/V. We find that the spectrum characteristics of EO polymer waveguide gratings depend strongly on many grating parameters, such as refractive-index modulation, modulation function, grating period, and period number. Material selection, fabrication technology, EO tuning ability, and polarization dependence of EO polymer waveguide gratings are also discussed. Such a waveguide grating not only overcomes the disadvantages of fiber-optic gratings, such as slow wavelength tuning ability and large-scale integration inconvenience, but also has many advantages, such as high resonant-wavelength tuning sensitivity, the same fabrication technology used for semiconductors, and polarization independence. PMID:16007840
Quantum Hamiltonian theory of an electro-optical modulator
NASA Astrophysics Data System (ADS)
Miroshnichenko, G. P.; Gleim, A. V.
A Quantum Hamiltonian formalism is proposed for the description of an electro-optical modulator based on the linear Pockels effect. Optical photons interact with photons of a microwave mode in a combined high- Q cavity made of a LiNbO3 crystal. The microwave photons occupy a coherent state, while optical photons have an arbitrary density matrix. The spectrum of a photodetected modulated signal is analyzed as a function of the frequency of a tunable optical filter. Numerical estimates are obtained, and quantum effects in the spectrum, such as the red shift of the central frequency and sidebands, the possibility of modulation of the optical signal by the microwave field vacuum, and the asymmetry of the intensity of the spectral sidebands, are discussed.
Degradation of electro-optic components aboard LDEF
NASA Technical Reports Server (NTRS)
Blue, M. D.
Remeasurement of the properties of a set of electro-optic components exposed to the low-earth environment aboard the Long Duration Exposure Facility (LDEF) indicates that most components survived quite well. Typical components showed some effects related to the space environment unless well protected. The effects were often small but significant. Results for semiconductor infrared detectors, lasers, and LED's, as well as filters, mirrors, and black paints are described. Semiconductor detectors and emitters were scarred but reproduced their original characteristics. Spectral characteristics of multi-layer dielectric filters and mirrors were found to be altered and degraded. Increased absorption in black paints indicates an increase in absorption sites, giving rise to enhanced performance as coatings for baffles and sunscreens.
We have made the first observation of a charged particle beam by means of its electro-optical effect on the propagation of laser light in a birefringent crystal at the Brookhaven National Laboratory Accelerator Test Facility. Polarized infrared light was coupled to a LiNbO{sub 3} crystal through a polarization maintaining fiber of 4 micron diameter. An electron beam in 10 ps bunches of 1 mm diameter was scanned across the crystal. The modulation of the laser light during passage of the electron beam was observed using a photodiode with 45 GHz bandwidth. The fastest rise time measured, 120 ps, was made in the single shot mode and was limited by the bandwidth of the oscilloscope and the associated electronics. Both polarization dependent and polarization independent effects were observed. This technology holds promise of greatly improved spatial and temporal resolution of charged particle beams.
Electro-Optical Plasmonic Switch Based On Graphene
NASA Astrophysics Data System (ADS)
Park, Suk-Young; Moon, Kyungsun
We have studied an electro-optical plasmonic waveguide, which controls the transmission of incident light by switching the coupling of the surface plasmon polariton (SPP) localized on graphene. It has been previously shown that the propagation length of the SPP localized on the copper surface can be effectively reduced by a factor of two or three by applying external bias potential. In our study, we have demonstrated that the propagation length of the SPP localized on graphene can be dramatically reduced by a factor of ten or so and the wavelength of SPP can be reduced by several hundredths of the incident light as well. This may help develop a nano-scale plasmonic switch. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (NRF-2012R1A1A2006927).
Solid state electro-optic color filter and iris
NASA Technical Reports Server (NTRS)
A pair of solid state electro-optic filters (SSEF) in a binocular holder were designed and fabricated for evaluation of field sequential stereo TV applications. The electronic circuitry for use with the stereo goggles was designed and fabricated, requiring only an external video input. A polarizing screen suitable for attachment to various size TV monitors for use in conjunction with the stereo goggles was designed and fabricated. An improved engineering model 2 filter was fabricated using the bonded holder technique developed previously and integrated to a GCTA color TV camera. An engineering model color filter was fabricated and assembled using PLZT control elements. In addition, a ruggedized holder assembly was designed, fabricated and tested. This assembly provides electrical contacts, high voltage protection, and support for the fragile PLZT disk, and also permits mounting and optical alignment of the associated polarizers.
Voigt waves in electro-optic homogenized composite materials
NASA Astrophysics Data System (ADS)
Mackay, Tom G.
A study was undertaken into Voigt wave propagation in a homogenized composite material (HCM). The HCM investigated arose from a porous electro-optic host material infiltrated by a fluid of refractive index na, considered in the long-wavelength regime. The extended Bruggeman homogenization formalism was employed to estimate the constitutive parameters of the HCM. In principle, the directions which support Voigt wave propagation in the HCM may be controlled by means of an applied dc electric field; and the degree of control may be sensitive to the porosity of the host material, the shapes, sizes and orientations of the pores, as well as the refractive index na. Here the theoretical methodology is presented; numerical results are presented elsewhere.
Solid state electro-optic color filter and iris
NASA Technical Reports Server (NTRS)
The electro-optic properties of lanthanum-modified lead zirconate titanate (PLZT) ferroelectric ceramic material are evaluated when utilized as a variable density and/or spectral filter in conjunction with a television scanning system. Emphasis was placed on the development of techniques and procedures for processing the PLZT disks and for applying efficient electrode structures. A number of samples were processed using different combinations of cleaning, electrode material, and deposition process. Best overall performance resulted from the direct evaporation of gold over chrome electrodes. A ruggedized mounting holder assembly was designed, fabricated, and tested. The assembly provides electrical contacts, high voltage protection, and support for the fragile PLZT disk, and permits mounting and optical alignment of the associated polarizers. Operational measurements of a PLZT sample mounted in the holder assembly were performed in conjunction with a television camera and the associated drive circuits. The data verified achievement of the elimination of the observed white-line effect.
Electro-optical switching and memory display device
Skotheim, Terje A.; O'Grady, William E.; Linkous, Clovis A.
An electro-optical display device having a housing with wall means including one transparent wall and at least one other wall. Counter electrodes are positioned on the transparent wall and display electrodes are positioned on the other wall with both electrodes in electrically conductive relationship with an electrolyte. Circuit means are connected to the display and counter electrodes to apply different predetermined control potentials between them. The display electrodes are covered with a thin electrically conductive polymer film that is characterized according to the invention by having embedded in it pigment molecules as counter ions. The display device is operable to be switched to a plurality of different visual color states at an exceptionally rapid switching rate while each of the color states is characterized by possessing good color intensity and definition.
Electro-optical switching and memory display device
Skotheim, T.A.; O'Grady, W.E.; Linkous, C.A.
An electro-optical display device having a housing with wall means including one transparent wall and at least one other wall. Counter electrodes are positioned on the transparent wall and display electrodes are positioned on the other wall with both electrodes in electrically conductive relationship with an electrolyte. Circuits means are connected to the display and counter electrodes to apply different predetermined control potentials between them. The display electrodes are covered with a thin electrically conductive polymer film that is characterized according to the invention by having embedded in it pigment molecules as counter ions. The display device is operable to be switched to a plurality of different visual color states at an exceptionally rapid switching rate while each of the color states is characterized by possessing good color intensity and definition.
Design principles and realization of electro-optical circuit boards
NASA Astrophysics Data System (ADS)
Betschon, Felix; Lamprecht, Tobias; Halter, Markus; Beyer, Stefan; Peterson, Harry
The manufacturing of electro-optical circuit boards (EOCB) is based to a large extent on established technologies. First products with embedded polymer waveguides are currently produced in series. The range of applications within the sensor and data communication markets is growing with the increasing maturity level. EOCBs require design flows, processes and techniques similar to existing printed circuit board (PCB) manufacturing and appropriate for optical signal transmission. A key aspect is the precise and automated assembly of active and passive optical components to the optical waveguides which has to be supported by the technology. The design flow is described after a short introduction into the build-up of EOCBs and the motivation for the usage of this technology within the different application fields. Basis for the design of EOCBs are the required optical signal transmission properties. Thereafter, the devices for the electro-optical conversion are chosen and the optical coupling approach is defined. Then, the planar optical elements (waveguides, splitters, couplers) are designed and simulated. This phase already requires co-design of the optical and electrical domain using novel design flows. The actual integration of an optical system into a PCB is shown in the last part. The optical layer is thereby laminated to the purely electrical PCB using a conventional PCB-lamination process to form the EOCB. The precise alignment of the various electrical and optical layers is thereby essential. Electrical vias are then generated, penetrating also the optical layer, to connect the individual electrical layers. Finally, the board has to be tested electrically and optically.
Multifunctional metasurface lens for imaging and Fourier transform
NASA Astrophysics Data System (ADS)
Wen, Dandan; Yue, Fuyong; Ardron, Marcus; Chen, Xianzhong
A metasurface can manipulate light in a desirable manner by imparting local and space-variant abrupt phase change. Benefiting from such an unprecedented capability, the conventional concept of what constitutes an optical lens continues to evolve. Ultrathin optical metasurface lenses have been demonstrated based on various nanoantennas such as V-shape structures, nanorods and nanoslits. A single device that can integrate two different types of lenses and polarities is desirable for system integration and device miniaturization. We experimentally demonstrate such an ultrathin metasurface lens that can function either as a spherical lens or a cylindrical lens, depending on the helicity of the incident light. Helicity-controllable focal line and focal point in the real focal plane, as well as imaging and 1D/2D Fourier transforms, are observed on the same lens. Our work provides a unique tool for polarization imaging, image processing and particle trapping.
Instrument concept of the imaging Fourier transform spectrometer GLORIA
NASA Astrophysics Data System (ADS)
Friedl-Vallon, F.; Gulde, T.; Hase, F.; Kleinert, A.; Kulessa, T.; Maucher, G.; Neubert, T.; Olschewski, F.; Piesch, C.; Preusse, P.; Rongen, H.; Sartorius, C.; Schneider, H.; Schönfeld, A.; Tan, V.; Bayer, N.; Blank, J.; Dapp, R.; Ebersoldt, A.; Fischer, H.; Graf, F.; Guggenmoser, T.; Höpfner, M.; Kaufmann, M.; Kretschmer, E.; Latzko, T.; Nordmeyer, H.; Oelhaf, H.; Orphal, J.; Riese, M.; Schardt, G.; Schillings, J.; Sha, M. K.; Suminska-Ebersoldt, O.; Ungermann, J.
The Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) is an imaging limb emission sounder operating in the thermal infrared region. It is designed to provide measurements of the Upper Troposphere/Lower Stratosphere with high spatial and high spectral resolution. The instrument consists of an imaging Fourier transform spectrometer integrated in a gimbal. The assembly can be mounted in the belly pod of the German high altitude and long range research aircraft HALO and in instrument bays of the Russian M55 Geophysica. Measurements are made predominantly in two distinct modes: the chemistry mode emphasises chemical analysis with high spectral resolution, the dynamics mode focuses on dynamical processes of the atmosphere with very high spatial resolution. In addition the instrument allows tomographic analyses of air volumes. The first measurement campaigns have shown compliance with key performance and operational requirements.
Instrument concept of the imaging Fourier transform spectrometer GLORIA
NASA Astrophysics Data System (ADS)
Friedl-Vallon, F.; Gulde, T.; Hase, F.; Kleinert, A.; Kulessa, T.; Maucher, G.; Neubert, T.; Olschewski, F.; Piesch, C.; Preusse, P.; Rongen, H.; Sartorius, C.; Schneider, H.; Schönfeld, A.; Tan, V.; Bayer, N.; Blank, J.; Dapp, R.; Ebersoldt, A.; Fischer, H.; Graf, F.; Guggenmoser, T.; Höpfner, M.; Kaufmann, M.; Kretschmer, E.; Latzko, T.; Nordmeyer, H.; Oelhaf, H.; Orphal, J.; Riese, M.; Schardt, G.; Schillings, J.; Sha, M. K.; Suminska-Ebersoldt, O.; Ungermann, J.
The Gimballed Limb Observer for Radiance Imaging of the Atmosphere (GLORIA) is an imaging limb emission sounder operating in the thermal infrared region. It is designed to provide measurements of the upper troposphere/lower stratosphere with high spatial and high spectral resolution. The instrument consists of an imaging Fourier transform spectrometer integrated into a gimbal. The assembly can be mounted in the belly pod of the German High Altitude and Long Range research aircraft (HALO) and in instrument bays of the Russian M55 Geophysica. Measurements are made in two distinct modes: the chemistry mode emphasises chemical analysis with high spectral resolution, and the dynamics mode focuses on dynamical processes of the atmosphere with very high spatial resolution. In addition, the instrument allows tomographic analyses of air volumes. The first measurement campaigns have shown compliance with key performance and operational requirements.
Multifunctional metasurface lens for imaging and Fourier transform
Wen, Dandan; Yue, Fuyong; Ardron, Marcus; Chen, Xianzhong
A metasurface can manipulate light in a desirable manner by imparting local and space-variant abrupt phase change. Benefiting from such an unprecedented capability, the conventional concept of what constitutes an optical lens continues to evolve. Ultrathin optical metasurface lenses have been demonstrated based on various nanoantennas such as V-shape structures, nanorods and nanoslits. A single device that can integrate two different types of lenses and polarities is desirable for system integration and device miniaturization. We experimentally demonstrate such an ultrathin metasurface lens that can function either as a spherical lens or a cylindrical lens, depending on the helicity of the incident light. Helicity-controllable focal line and focal point in the real focal plane, as well as imaging and 1D/2D Fourier transforms, are observed on the same lens. Our work provides a unique tool for polarization imaging, image processing and particle trapping. PMID:27272601
Multifunctional metasurface lens for imaging and Fourier transform.
Wen, Dandan; Yue, Fuyong; Ardron, Marcus; Chen, Xianzhong
A metasurface can manipulate light in a desirable manner by imparting local and space-variant abrupt phase change. Benefiting from such an unprecedented capability, the conventional concept of what constitutes an optical lens continues to evolve. Ultrathin optical metasurface lenses have been demonstrated based on various nanoantennas such as V-shape structures, nanorods and nanoslits. A single device that can integrate two different types of lenses and polarities is desirable for system integration and device miniaturization. We experimentally demonstrate such an ultrathin metasurface lens that can function either as a spherical lens or a cylindrical lens, depending on the helicity of the incident light. Helicity-controllable focal line and focal point in the real focal plane, as well as imaging and 1D/2D Fourier transforms, are observed on the same lens. Our work provides a unique tool for polarization imaging, image processing and particle trapping. PMID:27272601
Medical Image Processing Using Real-Time Optical Fourier Technique
NASA Astrophysics Data System (ADS)
Rao, D. V. G. L. N.; Panchangam, Appaji; Sastry, K. V. L. N.; Material Science Team
Optical Image Processing Techniques are inherently fast in view of parallel processing. A self-adaptive Optical Fourier Processing system using photo induced dichroism in a Bacteriorhodopsin film was experimentally demonstrated for medical image processing. Application of this powerful analog all-optical interactive technique for cancer diagnostics is illustrated with mammograms and Pap smears. Micro calcification clusters buried in surrounding tissue showed up clearly in the processed image. By playing with one knob, which rotates the analyzer in the optical system, either the micro calcification clusters or the surrounding dense tissue can be selectively displayed. Bacteriorhodopsin films are stable up to 140^oC and environmental friendly. As no interference is involved in the experiments, vibration isolation and even a coherent light source are not required. It may be possible to develop a low-cost rugged battery operated portable signal-enhancing magnifier.
Color image encryption based on joint fractional Fourier transform correlator
NASA Astrophysics Data System (ADS)
Lu, Ding; Jin, Weimin
In this paper, an optical color image encryption/decryption technology based on joint fractional Fourier transform correlator and double random phase encoding (DRPE) is developed. In this method, the joint fractional power spectrum of the image to be encrypted and the key codes is recorded as the encrypted data. Different from the case with classical DRPE, the same key code was used both in the encryption and decryption. The security of the system is enhanced because of the fractional order as a new added key. This method takes full advantage of the parallel processing features of the optical system, and could optically realize single-channel color image encryption. The experimental results indicate that the new method is feasible.
The gridding method for image reconstruction by Fourier transformation
Schomberg, H.; Timmer, J.
This paper explores a computational method for reconstructing an n-dimensional signal f from a sampled version of its Fourier transform {cflx f}. The method involves a window function {cflx w} and proceeds in three steps. First, the convolution {cflx g} = {cflx w} * {cflx f} is computed numerically on a Cartesian grid, using the available samples of {cflx f}. Then, g = wf is computed via the inverse discrete Fourier transform, and finally f is obtained as g/w. Due to the smoothing effect of the convolution, evaluating {cflx w} * {cflx f} is much less error prone than merely interpolating {cflx f}. The method was originally devised for image reconstruction in radio astronomy, but is actually applicable to a broad range of reconstructive imaging methods, including magnetic resonance imaging and computed tomography. In particular, it provides a fast and accurate alternative to the filtered backprojection. The basic method has several variants with other applications, such as the equidistant resampling of arbitrarily sampled signals or the fast computation of the Radon (Hough) transform.
Grid-Based Fourier Transform Phase Contrast Imaging
NASA Astrophysics Data System (ADS)
Tahir, Sajjad
Low contrast in x-ray attenuation imaging between different materials of low electron density is a limitation of traditional x-ray radiography. Phase contrast imaging offers the potential to improve the contrast between such materials, but due to the requirements on the spatial coherence of the x-ray beam, practical implementation of such systems with tabletop (i.e. non-synchrotron) sources has been limited. One recently developed phase imaging technique employs multiple fine-pitched gratings. However, the strict manufacturing tolerances and precise alignment requirements have limited the widespread adoption of grating-based techniques. In this work, we have investigated a technique recently demonstrated by Bennett et al. that utilizes a single grid of much coarser pitch. Our system consisted of a low power 100 microm spot Mo source, a CCD with 22 microm pixel pitch, and either a focused mammography linear grid or a stainless steel woven mesh. Phase is extracted from a single image by windowing and comparing data localized about harmonics of the grid in the Fourier domain. A Matlab code was written to perform the image processing. For the first time, the effects on the diffraction phase contrast and scattering amplitude images of varying grid types and periods, and of varying the window function type used to separate the harmonics, and the window widths, were investigated. Using the wire mesh, derivatives of the phase along two orthogonal directions were obtained and new methods investigated to form improved phase contrast images.
Assessment of Spacecraft Operational Status Using Electro-Optical Predictive Techniques
NASA Astrophysics Data System (ADS)
Swann, D.; Klem, B.; McCoy, B.
The current class of small satellite systems presents an analyst responsible for monitoring spacecraft operational status and early detection of detrimental anomalies with a broad variety of sensing and identification issues and challenges. Simple, small, cube-shaped satellites, without protruding solar panel appendages, may require enhanced preflight characterization processes to support monitoring by passive, remote, nonimaging optical sensors. This paper will describe spacecraft optical signature modeling and simulation techniques to develop sensing and identification algorithms for observing and characterizing key spacecraft features. The simulation results are based on electro-optical signatures apparent to nonimaging sensors, along with related observable features derived from multicolor and multiviewing aspect scenarios. This model and simulation analysis capability is used to support programs to monitor spacecraft performance status and identify anomalies associated with spacecraft damage/deterioration due to space debris or micrometeorite impact, thruster exhaust deposition or material aging. The development of state-of-the-art optical signature modeling tools to perform high-fidelity satellite models (such as the Air Force Academy FalconSat-5 or AFRL TacSat-3) simulations to characterize spectral radiant intensities apparent to passive, remote, nonresolved imaging sensors are described in detail. Simulations are performed for a comprehensive scenario range of natural (solar and earth) illumination and viewing conditions. Results are generated for comparing baseline, streamlined geometry models with the actual higher fidelity models that capture vehicle small-size hardware components and modifications. Output consisting of radiant intensity history apparent to ground-based sensor locations for vehicle trajectories that capture a comprehensive range of illumination conditions from the sun and underlying earth scene are presented for extensive spectral band
Quantification of helicopter rotor downwash effects on electro-optical defensive aids suites
NASA Astrophysics Data System (ADS)
Seiffer, Dirk P.; Eisele, Christian; Henriksson, Markus; Sjöqvist, Lars; Möller, Sebastian; Togna, Fabio; Velluet, Marie-Thérèse
The performance of electro-optical platform protection systems can be degraded significantly by the propagation environment around the platform. This includes aero-optical effects and zones of severe turbulence generated by engine exhausts. For helicopters rotor tip vortices and engine exhaust gases that are pressed down by the rotor airflow form the so called downwash phenomena. The downwash is a source for perturbations. A wide range of spatial and temporal fluctuations in the refractive index of air can occur. The perturbations from the turbulent flow cause detrimental effects on energy delivery, angle of arrival fluctuations, jam-code transmission, tracking accuracy and imaging performance in general. Therefore the effects may especially have a severe impact on the performance of laser-based protection systems like directed infrared countermeasures (DIRCM). The chain from passive missile detection and warning to obtaining an optical break-lock by the use of an active laser system will be influenced. To anticipate the installed performance of an electro-optical defensive aids suite (DAS) for helicopter platforms it is necessary to develop models for the prediction of the perturbations. Modelled results have to be validated against experimental findings. However, the data available in open literature on the effects of rotor downwash from helicopters on optical propagation is very limited. To collect necessary data and to obtain a first impression about the magnitude of occurring effects the European defence agency group (EDA) on "airborne platform effects on lasers and warning sensors (ALWS)" decided to design and perform a field trial on the premises of the Italian Air Force Flight Test Center in Pratica di Mare, Italy. ALWS is a technical arrangement under the Europa MoU among France, Germany, Italy, Sweden and the United Kingdom.
High throughput full Stokes Fourier transform imaging spectropolarimetry.
Meng, Xin; Li, Jianxin; Xu, Tingting; Liu, Defang; Zhu, Rihong
A complete full Stokes imaging spectropolarimeter is proposed. Four separate polarized spectra are fed into the Sagnac Fourier transform spectrometer without slit using different angle combinations of the polarized elements. The four polarized spectra are separated without spatial aliasing. And the system has a good performance to resist the instrument noise due to its high light throughput. The mathematical model for the approach is derived and an optimization of the retardance is discussed. For acquiring the four spectra simultaneously, an improved robust polarization modulator using aperture division is outlined. Then the system is discussed in detail including the imaging principle and spectral resolution. Lastly, two proven experiments are carried out and the experimental results in visible light are outlined. PMID:24514802
Ultrahigh speed spectral/Fourier domain ophthalmic OCT imaging
NASA Astrophysics Data System (ADS)
Potsaid, Benjamin; Gorczynska, Iwona; Srinivasan, Vivek J.; Chen, Yueli; Liu, Jonathan; Jiang, James; Cable, Alex; Duker, Jay S.; Fujimoto, James G.
Ultrahigh speed spectral / Fourier domain optical coherence tomography (OCT) imaging using a CMOS line scan camera with acquisition rates of 70,000 - 312,500 axial scans per second is investigated. Several design configurations are presented to illustrate trade-offs between acquisition speed, sensitivity, resolution and sensitivity roll-off performance. We demonstrate: extended imaging range and improved sensitivity roll-off at 70,000 axial scans per second , high speed and ultrahigh resolution imaging at 106,382 axial scans per second, and ultrahigh speed imaging at 250,000-312,500 axial scans per second. Each configuration is characterized through optical testing and the trade-offs demonstrated with in vivo imaging of the fovea and optic disk in the human retina. OCT fundus images constructed from 3D-OCT data acquired at 250,000 axial scans per second have no noticeable discontinuity of retinal features and show that there are minimal motion artifacts. The fine structures of the lamina cribrosa can be seen. Long cross sectional scans are acquired at 70,000 axial scans per second for imaging large areas of the retina, including the fovea and optic disk. Rapid repeated imaging of a small volume (4D-OCT) enables time resolved visualization of the capillary network surrounding the INL and may show individual red blood cells. The results of this study suggest that high speed CMOS cameras can achieve a significant improvement in performance for ophthalmic imaging. This promises to have a powerful impact in clinical applications by improving early diagnosis, reproducibility of measurements and enabling more sensitive assessment of disease progression or response to therapy.
Evaluation of active and passive polarimetric electro-optic imagery for civilian and military targets discrimination
NASA Astrophysics Data System (ADS)
Lavigne, Daniel A.; Breton, Mélanie; Pichette, Mario; Larochelle, Vincent; Simard, Jean-Robert
Electro-optic (EO) imaging systems are commonly used to detect civilian and military targets during surveillance operations and search and rescue missions. Adding the polarization of light as additional information to such active and passive EO imaging systems may increase the target discrimination performance, as man made objects are known to depolarized light in different manner than natural background. However, while the polarization of light has been used and studied in the past for numerous applications, the understanding of the polarization phenomenology taking place with targets used in cluttered backgrounds requires additional experimentations. Specifically, the target contrast enhancement obtained by analyzing the polarization of the reflected light from either a direct polarized laser source as encountered in active imagers, or from natural ambient illumination, needs further investigation. This paper describes an investigation of the use of polarization-based imaging sensors to discriminate civilian and military targets against different backgrounds. Measurements were carried out using two custom-designed active and passive imaging systems operating in the near infrared (NIR) and the long-wave infrared (LWIR) spectral bands. Polarimetric signatures were acquired during two distinct trials that occurred in 2007, using specific civilian and military targets such as cars and military vehicles. Results demonstrate to what extent and under which illumination and environmental conditions the exploitation of active and passive polarimetric images is suitable to enable target detection and recognition for some events of interest, according to various specific scenarios.
Future electro-optical sensors and processing in urban operations
NASA Astrophysics Data System (ADS)
Grönwall, Christina; Schwering, Piet B.; Rantakokko, Jouni; Benoist, Koen W.; Kemp, Rob A. W.; Steinvall, Ove; Letalick, Dietmar; Björkert, Stefan
In the electro-optical sensors and processing in urban operations (ESUO) study we pave the way for the European Defence Agency (EDA) group of Electro-Optics experts (IAP03) for a common understanding of the optimal distribution of processing functions between the different platforms. Combinations of local, distributed and centralized processing are proposed. In this way one can match processing functionality to the required power, and available communication systems data rates, to obtain the desired reaction times. In the study, three priority scenarios were defined. For these scenarios, present-day and future sensors and signal processing technologies were studied. The priority scenarios were camp protection, patrol and house search. A method for analyzing information quality in single and multi-sensor systems has been applied. A method for estimating reaction times for transmission of data through the chain of command has been proposed and used. These methods are documented and can be used to modify scenarios, or be applied to other scenarios. Present day data processing is organized mainly locally. Very limited exchange of information with other platforms is present; this is performed mainly at a high information level. Main issues that arose from the analysis of present-day systems and methodology are the slow reaction time due to the limited field of view of present-day sensors and the lack of robust automated processing. Efficient handover schemes between wide and narrow field of view sensors may however reduce the delay times. The main effort in the study was in forecasting the signal processing of EO-sensors in the next ten to twenty years. Distributed processing is proposed between hand-held and vehicle based sensors. This can be accompanied by cloud processing on board several vehicles. Additionally, to perform sensor fusion on sensor data originating from different platforms, and making full use of UAV imagery, a combination of distributed and
Continued Development of a Planetary Imaging Fourier Transform Spectrometer (PIFTS)
NASA Technical Reports Server (NTRS)
Sromovsky, L. A.
This report describes continued efforts to evaluate a breadboard of a Planetary Imaging Fourier Transform Spectrometer (PIFTS). The PIFTS breadboard was developed under prior PIDDP funding. That effort is described in the final report for NASA Grant NAG5-6248 and in two conference papers (Sromovsky et al. 2000; Revercomb et al. 2000). The PIFTS breadboard was designed for near-IR (1-5.2 micrometer imaging of planetary targets with spectral resolving powers of several hundred to several thousand, using an InSb detector array providing at least 64x64 pixels imaging detail. The major focus of the development effort was to combine existing technologies to produce a small and low power design compatible with a very low mass flyable instrument. The objective of this grant (NAG5-10729) was further characterization of the breadboard performance, including intercomparisons with the highly accurate non-imaging Advanced Emitted Radiance Interferometer (AERI) (Revercomb et al. 1994; Best et al. 1997).
Calibration of the Geostationary Imaging Fourier Transform Spectrometer (GIFTS)
NASA Technical Reports Server (NTRS)
Best, F. A.; Revercomb, H. E.; Bingham, G. E.; Knuteson, R. O.; Tobin, D. C.; LaPorte, D. D.; Smith, W. L.
The NASA New Millennium Program's Geostationary Imaging Fourier Transform Spectrometer (GIFTS) requires highly accurate radiometric and spectral calibration in order to carry out its mission to provide water vapor, wind, temperature, and trace gas profiling from geostationary orbit. A calibration concept has been developed for the GIFTS Phase A instrument design. The in-flight calibration is performed using views of two on-board blackbody sources along with cold space. A radiometric calibration uncertainty analysis has been developed and used to show that the expected performance for GIFTS exceeds its top level requirement to measure brightness temperature to better than 1 K. For the Phase A GIFTS design, the spectral calibration is established by the highly stable diode laser used as the reference for interferogram sampling, and verified with comparisons to atmospheric calculations.
Susceptibility of electro-optic components to degradation in a space environment.
Blue, M D
Possible causes of degradation of electro-optic systems operating in a space environment include not only the effects of radiation but also the effects of temperature, temperature cycling, atomic oxygen effects (for low-Earth orbits), micrometeoroid impacts, and contamination effects. For the majority of electro-optic components, the radiation environment in space does not present a significant problem. For a few components, or for electro-optic systems that must operate in a high radiation environment, special precautions must be observed. The effects of radiation, as well as other problems of the space environment, on electro-optic components, including recent results from the LDEF satellite experiments and some later measurements, are reviewed. Guidelines for materials and component selection shielding are presented. PMID:11540513
Tunable Optical Filters Having Electro-optic Whispering-gallery-mode Resonators
NASA Technical Reports Server (NTRS)
Savchenkov, Anatoliy (Inventor); Ilchenko, Vladimir (Inventor); Matsko, Andrey B. (Inventor); Maleki, Lutfollah (Inventor)
Tunable optical filters using whispering-gallery-mode (WGM) optical resonators are described. The WGM optical resonator in a filter exhibits an electro-optical effect and hence is tunable by applying a control electrical signal.
High frequency electro-optic measurement of strained silicon racetrack resonators
NASA Astrophysics Data System (ADS)
Borghi, Massimo; Mancinelli, Mattia; Merget, Florian; Witzens, Jeremy; Bernard, Martino; Ghulinyan, Mher; Pucker, Georg; Pavesi, Lorenzo
In this paper, we report on time resolved electro-optic measurements in strained silicon resonators. Strain is induced by applying a mechanical deformation to the device. It is demonstrated that the linear electro-optic effect vanishes when the applied voltage modulation varies much faster than the free carrier lifetime, and that this occurs independently on the level of the applied stress. This demonstrates that, at frequencies which lie below the free carrier recombination rate, the electro-optic modulation is caused by plasma carrier dispersion. After normalizing out free carrier effects, it is found an upper limit of (8 +/- 3) pm/V to the value of the strain induced χ(2)eff, zzz tensor component. This is an order of magnitude lower than the previously reported values for static electro-optic measurements.
Electro-optic and acousto-optic laser beam scanners
NASA Astrophysics Data System (ADS)
Heberle, Johannes; Bechtold, Peter; Strauß, Johannes; Schmidt, Michael
Electro-optical deflectors (EOD) and acousto-optical deflectors (AOD) are based on deflection of laser light within a solid state medium. As they do not contain any moving parts, they yield advantages compared to mechanical scanners which are conventionally used for laser beam deflection. Even for arbitrary scan paths high feed rates can be achieved. In this work the principles of operation and characteristic properties of EOD and AOD are presented. Additionally, a comparison to mirror based mechanical deflectors regarding deflection angles, speed and accuracy is made in terms of resolvable spots and the rate of resolvable spots. Especially, the latter one is up to one order of magnitude higher for EOD and AOD systems compared to conventional systems. Further characteristic properties such as response time, damage threshold, efficiency and beam distortions are discussed. Solid state laser beam deflectors are usually characterized by small deflection angles but high angular deflection velocities. As mechanical deflectors exhibit opposite properties an arrangement of a mechanical scanner combined with a solid state deflector provides a solution with the benefits of both systems. As ultrashort pulsed lasers with average power above 100 W and repetition rates in the MHz range have been available for several years this approach can be applied to fully exploit their capabilities. Thereby, pulse overlap can be reduced and by this means heat affected zones are prevented to provide proper processing results.
A high average power electro-optic switch using KTP
Ebbers, C.A.; Cook, W.M.; Velsko, S.P.
High damage threshold, high thermal conductivity, and small thermo-optic coefficients make KTiOPO{sub 4} (KTP) an attractive material for use in a high average power Q-switch. However, electro-chromic damage and refractive index homogeneity have prevented the utilization of KTP in such a device in the past. This work shows that electro-chromic damage is effectively suppressed using capacitive coupling, and a KTP crystal can be Q-switched for 1.5 {times} 10{sup 9} shots without any detectable electro-chromic damage. In addition, KTP with the high uniformity and large aperture size needed for a KTP electro-optic Q-switch can be obtained from flux crystals grown at constant temperature. A thermally compensated, dual crystal KTP Q-switch, which successfully produced 50 mJ pulses with a pulse width of 8 ns (FWHM), has been constructed. In addition, in off-line testing the Q-switch showed less than 7% depolarization at an average power loading of 3.2 kW/cm{sup 2}.
Evaluation of the electro-optic direction sensor
NASA Technical Reports Server (NTRS)
Johnson, A. R.; Salomon, P. M.
Evaluation of a no-moving-parts single-axis star tracker called an electro-optic direction sensor (EODS) concept is described and the results are given in detail. The work involved experimental evaluation of a breadboard sensor yielding results which would permit design of a prototype sensor for a specific application. The laboratory work included evaluation of the noise equivalent input angle of the sensor, demonstration of a technique for producing an acquisition signal, constraints on the useful field-of-view, and a qualitative evaluation of the effects of stray light. In addition, the potential of the silicon avalanche-type photodiode for this application was investigated. No benefit in noise figure was found, but the easily adjustable gain of the avalanche device was useful. The use of mechanical tuning of the modulating element to reduce voltage requirements was also explored. The predicted performance of EODS in both photomultiplier and solid state detector configurations was compared to an existing state-of-the-art star tracker.
Enhanced electro-optic response in domain-engineered LiNbO3 channel waveguides
NASA Astrophysics Data System (ADS)
Zisis, G.; Ying, C. Y. J.; Ganguly, P.; Sones, C. L.; Soergel, E.; Eason, R. W.; Mailis, S.
Substantial enhancement (36.7%) of the intrinsic electro-optic coefficient ( r33) has been observed in lithium niobate channel waveguides, which are made to overlap with a pole-inhibited ferroelectric domain. The waveguide and the overlapping ferroelectric domain are both produced by a single UV irradiation process and are thus self-aligning. The enhancement of the electro-optic coefficient effect is attributed to strain, which is associated with the ferroelectric domain boundaries that contain the channel waveguide.
Electro-optic modulation in hybrid solgel doped with Disperse Red chromophore.
Lu, Dong; Zhang, Hongxi; Fallahi, Mahmoud
An electro-optically active hybrid solgel doped with Disperse Red 13 has been developed by use of a simple solvent-assisted method. It permits a high loading concentration and has low optical loss at 1550 nm. A channel waveguide amplitude modulator has been fabricated by use of active and passive hybrid solgel materials. The device shows an electro-optic coefficient of 14 pm/V at 1550 nm and stable operation. PMID:15751884
Electro-optic modulation in hybrid solgel doped with Disperse Red chromophore
NASA Astrophysics Data System (ADS)
Lu, Dong; Zhang, Hongxi; Fallahi, Mahmoud
An electro-optically active hybrid solgel doped with Disperse Red 13 has been developed by use of a simple solvent-assisted method. It permits a high loading concentration and has low optical loss at 1550 nm. A channel waveguide amplitude modulator has been fabricated by use of active and passive hybrid solgel materials. The device shows an electro-optic coefficient of 14 pm/V at 1550 nm and stable operation.
Design and construction of an electro-optic RF metamaterial array
NASA Astrophysics Data System (ADS)
Chen, Weibin; Nelson, Robert L.; Zhan, Qiwen
Subwavelength metallic structures capable of creating strongly localized electromagnetic field with enormous enhancement under illumination/excitation are designed for direct radio frequency (RF) imaging. Three dimensional finite element method models are applied to investigate the electromagnetic field concentrations of two types of split ring resonators. Under appropriate linearly polarized illumination, a highly confined field located at the gap of the ring resonator is found due to strong scattering resonance. The numerical studies show that field enhancement as high as 6,800 is achieved for a planar D-shaped split ring resonator. The enhancement can be further increased through shrinking the gaps size or the ring width. Crescent shaped split ring resonator is designed for broadband application. It provides an enhanced bandwidth which is 1.15 times of the resonant frequency. The concentrated electromagnetic field facilitates nonlinear processes that find lots of applications. Optimized RF concentrators integrated with electro-optic modulators are demonstrated to directly modulate optical carrier. The combination of RF concentrator and EO modulator could enable a focal plane RF imager array that allows direct RF imaging, and significantly decrease RF aperture size and weight. Additional benefits include enhanced functionality such as inherent polarimetric imaging capability.
Multiresolution graph Fourier transform for compression of piecewise smooth images.
Hu, Wei; Cheung, Gene; Ortega, Antonio; Au, Oscar C
Piecewise smooth (PWS) images (e.g., depth maps or animation images) contain unique signal characteristics such as sharp object boundaries and slowly varying interior surfaces. Leveraging on recent advances in graph signal processing, in this paper, we propose to compress the PWS images using suitable graph Fourier transforms (GFTs) to minimize the total signal representation cost of each pixel block, considering both the sparsity of the signal's transform coefficients and the compactness of transform description. Unlike fixed transforms, such as the discrete cosine transform, we can adapt GFT to a particular class of pixel blocks. In particular, we select one among a defined search space of GFTs to minimize total representation cost via our proposed algorithms, leveraging on graph optimization techniques, such as spectral clustering and minimum graph cuts. Furthermore, for practical implementation of GFT, we introduce two techniques to reduce computation complexity. First, at the encoder, we low-pass filter and downsample a high-resolution (HR) pixel block to obtain a low-resolution (LR) one, so that a LR-GFT can be employed. At the decoder, upsampling and interpolation are performed adaptively along HR boundaries coded using arithmetic edge coding, so that sharp object boundaries can be well preserved. Second, instead of computing GFT from a graph in real-time via eigen-decomposition, the most popular LR-GFTs are pre-computed and stored in a table for lookup during encoding and decoding. Using depth maps and computer-graphics images as examples of the PWS images, experimental results show that our proposed multiresolution-GFT scheme outperforms H.264 intra by 6.8 dB on average in peak signal-to-noise ratio at the same bit rate. PMID:25494508
Internal model control of a fast steering mirror for electro-optical fine tracking
NASA Astrophysics Data System (ADS)
Xia, Yun-xia; Bao, Qi-liang; Wu, Qiong-yan
The objective of this research is to develop advanced control methods to improve the bandwidth and tracking precision of the electro-optical fine tracking system using a fast steering mirror (FSM). FSM is the most important part in this control system. The model of FSM is established at the beginning of this paper. Compared with the electro-optical fine tracking system with ground based platform, the electro-optical fine tracking system with movement based platform must be a wide bandwidth and a robustness system. An advanced control method based on internal model control law is developed for electro-optical fine tracking system. The IMC is an advanced algorithm. Theoretically, it can eliminate disturbance completely and make sure output equals to input even there is model error. Moreover, it separates process to the system dynamic characteristic and the object perturbation. Compared with the PID controller, the controller is simpler and the parameter regulation is more convenient and the system is more robust. In addition, we design an improved structure based on classic IMC. The tracking error of the two-port control system is much better than which of the classic IMC. The simulation results indicate that the electro-optical control system based on the internal model control algorithm is very effective. It shows a better performance at the tracing precision and the disturbance suppresses. Thus a new method is provided for the high-performance electro-optical fine tracking system.
Electro-optical detector for use in a wide mass range mass spectrometer
NASA Technical Reports Server (NTRS)
Giffin, Charles E. (Inventor)
An electro-optical detector is disclosed for use in a wide mass range mass spectrometer (MS), in the latter the focal plane is at or very near the exit end of the magnetic analyzer, so that a strong magnetic field of the order of 1000G or more is present at the focal plane location. The novel detector includes a microchannel electron multiplier array (MCA) which is positioned at the focal plane to convert ion beams which are focused by the MS at the focal plane into corresponding electron beams which are then accelerated to form visual images on a conductive phosphored surface. These visual images are then converted into images on the target of a vidicon camera or the like for electronic processing. Due to the strong magnetic field at the focal plane, in one embodiment of the invention, the MCA with front and back parallel ends is placed so that its front end forms an angle of not less than several degrees, preferably on the order of 10.degree.-20.degree., with respect to the focal plane, with the center line of the front end preferably located in the focal plane. In another embodiment the MCA is wedge-shaped, with its back end at an angle of about 10.degree.-20.degree. with respect to the front end. In this embodiment the MCA is placed so that its front end is located at the focal plane.
Imaging Fourier Transform Spectro-polarimetry in the Infrared
NASA Astrophysics Data System (ADS)
Jurgenson, C. A.; Stencel, R. E.; Stout, J.
Imaging spectro-polarimetry has the capability to trace polarization changes in dust grains throughout an extended region of interest. An instrument that has the capability to achieve moderately high resolution (R = 2000 at 10 microns) via a stepping Fourier transform spectrometer, while preserving imaging polarimetry capabilities (TNTCAM2, Jurgenson et al. 2003), is set to achieve first light during early 2005. Motion control of the interferometer, as well as array control/readout is accomplished via an FPGA card programmed in LabVIEW(c). Mid-IR polarization studies are useful in approximating grain shapes and sizes in dusty environments. Correlation studies between mid and near-IR features can be used to test the core-mantle arrangement of grain growth. Polarization analysis is currently only possible between 8-13 microns, but the interferometer, as well as TNTCAM2, can operate at selected bandpasses in the near-IR region. A wire grid and waveplate would need to be purchased for work in the near-IR. Laboratory calibration results, both spectral and polarization, are reported. We are seeking collaborators in shared-risk science with this instrument, so please contact the authors if interested. Sigma Xi Grants In Aid of Research as well as the estate of William Herschel Womble provided funding for this endeavor.
Electro-Optical Payloads and CubeSat Missions for Earth and Space Science
NASA Astrophysics Data System (ADS)
Swenson, C.; Marchant, A.
Small, low-power electro-optical scientific payloads are required if small satellites and CubeSats are to become significant enablers of new science. Although these are just one class of scientific instrumentation they have often played a key role in many scientific discoveries. The most significant advances in Earth and space science, over the next decade are most likely to derive from new observational techniques. The connection between advances in scientific understanding and technology has historically been demonstrated across many disciplines and time. In this paper we present a review of three such sensors and the associated CubeSat missions and scientific investigation enabled. Each mission involves a relatively recently developed small electro-optical sensor which is tightly integrated with the small satellite bus in to a "Science Craft". The first is the NSF funded OPAL mission which makes use of a high-sensitivity, hyper-spectral limb imager to observe the daytime O2 A-band (near 762nm) emission. These observations allow the temperature of the lower thermosphere to be determined and address questions on the energy budget and response of the thermosphere to geomagnetic storms. The second is the MeNISCuS mission Methane Nadir Imaging Spatial-heterodyne CubeSat Spectrometer which is a demonstration of the volume holographic grating (VHG) spatial heterodyne spectrometer developed under a NASA-sponsored STTR contract. Methane (CH4) is the second most important greenhouse gas and although burning methane produces less CO2 than oil or coal, methane's global warming potential is about ~30 times higher. As a result, if methane leak rates are greater than 3-5%, the warming potential will outweigh the benefit of reduced CO2. The sources of such leaks can be discovered using missions like MeNISCuS. The third instrument and mission is SEDI a CubeSat scaled Fabry-Perot spectrometer focused on a narrow band around the OI(630) red line for observing winds in the
Electro-optical properties investigation of a series of hydroxylphenylporphyrins
NASA Astrophysics Data System (ADS)
Shi, Yingyan; Zheng, Wenqi; Li, Ziheng; Wang, Xingqiao; Wang, Dejun; Qiu, Shilun; Li, Xiangqing
substituting groups of the porphyrin ring and using different solvents could obtain the porphyrins with different electro-optical properties.
Electro-optic and dielectric properties of photorefractive BaTiO3 and KNbO3
NASA Astrophysics Data System (ADS)
Zgonik, Marko; Nakagawa, Kiyoshi; Günter, Peter
Recently determined complete sets of materials parameters describing the dielectric, elastic, piezoelectric, elasto-optic, and electro-optic properties of BaTiO3 and KNbO3 crystals at room temperature are used to calculate the effective electro-optic coefficients and dielectric constants required for describing photorefractive phenomena. We show a substantial deviation of the new values from the electro-optic coefficients for homogeneously applied electric fields that were used previously in describing the photorefractive effects. We derive angular dependences of the effective electro-optic coefficients and the effective dielectric constants relevant for grating recording in both crystals and verify them experimentally.
Electric field induced biaxiality and the electro-optic effect in a bent-core nematic liquid crystal
NASA Astrophysics Data System (ADS)
Nagaraj, Mamatha; Panarin, Y. P.; Manna, U.; Vij, J. K.; Keith, C.; Tschierske, C.
We report the observation of a biaxial nematic phase in a bent-core molecular system using polarizing microscopy, electro-optics, and dielectric spectroscopy, where we find that the biaxiality exists on a microscopic scale. An application of electric field induces a macroscopic biaxiality and in consequence gives rise to electro-optic switching. This electro-optic effect shows significant potential in applications for displays due to its fast high-contrast response. The observed electro-optic switching is explained in terms of the interaction of the ferroelectric clusters with the electric field.
Organic-based electro-optic modulators for microwave photonic applications
NASA Astrophysics Data System (ADS)
Eng, David
As cutting-edge microwave photonic systems with higher complexity and stringent device requirement are being developed, the demand higher performance modulators with lower drive voltages and higher bandwidth is beginning to overtake the physical limitations of existing modulators based in LiNbO3. To address this growing demand, groundbreaking work in the field of organic electro-optic materials has been achieved over the past 10--15 years that has resulted in materials with electro-optic coefficients up to 10 times that of LiNbO3 and with demonstrated response times into the THz regime. This dissertation details work towards developing low drive-voltage, high bandwidth organic-based electro-optic modulators to support next generation microwave photonic systems. Initial efforts were focused on designing an organic electro-optic material based low frequency phase modulator and developing a fabrication procedure that successfully integrates the material without compromising its electro optic activity. Additionally a procedure for inducing the high electro-optic activity in the waveguide core through a process known as 'poling' was developed. The phase modulators were then characterized to confirm the expected high electro-optic activity and correspondingly low drive voltages. To transition from low frequency modulation to broadband operation it was necessary to gather some dielectric information of the waveguide materials for RF design. Because traditional RF dielectric constant measurements assume thick substrates on the order of 100s of microns, a modified microstrip ring resonator technique was developed to measure the dielectric constant of thin, polymer waveguide films on the order of 10 mum out to 110 GHz. A high frequency traveling wave microstrip modulator was then designed and optimized for operation up to 50 GHz, and efforts were turned towards RF packaging of the microstrip modulators for practical utilization and integration. To feed the RF signals a
Numerical Modeling and Analysis of Optical Response of Electro-optic Modulators
Hussein, Y
This paper presents an analysis of a LiNbO{sub 3} electro-optic modulator using the Finite Difference Time Domain (FDTD) technique, and also a new and efficient multiresolution time-domain technique for fast and accurate modeling of photonic devices. The electromagnetic fields computed by FDTD are coupled to standard electro-optic relations that characterize electro-optic interactions. This novel approach to LiNbO{sub 3} electro-optic modulators using a coupled FDTD technique allows for previously unattainable investigations into device operating bandwidth and data transmission speed. On the other hand, the proposed multiresolution approach presented in this paper solves Maxwell's Equations on nonuniform self-adaptive grids, obtained by applying wavelet transforms followed by hard thresholding. The developed technique is employed to simulate a coplanar waveguide CPW, which represents an electro-optic modulator. Different numerical examples are presented showing more than 75% CPU-time reduction, while maintaining the same degree of accuracy of standard FDTD techniques.
Electro-optic property of ZnO:X (X=Li,Mg) thin films
NASA Astrophysics Data System (ADS)
Nagata, Takahiro; Shimura, Tamaki; Ashida, Atsushi; Fujimura, Norifumi; Ito, Taichiro
We have proposed an application of ZnO:X (X=Li,Mg,Ni,Al etc.) films for monolithic optical integrated circuits (OICs) (Mat. Res. Soc. Symp. Proc. 574 (1999) 317). Although non-doped ZnO has an electro-optic effect, it is only a Pockel's effect. The electro-optic effect of Pb(Zr,Ti)O 3 (Jpn. J. Appl. Phys. 34 (1995) 5091) is superior to ZnO, because that is caused by a non-linear Kerr effect. Our group demonstrated that Li-doped ZnO (ZnO:Li) films exhibited ferroelectric behavior (Appl. Phys. A, in press). ZnO with ferroelectricity should have a non-linear electro-optic effect against the applied voltage. In this paper, to design the ZnO monolithic slab waveguide for electro-optical switch, the refractive indices of top and bottom electrode layers and core layer were investigated. Then, electro-optical property of ZnO:Li,Mg films was evaluated, and the possibility of applying to an optical switch was also discussed.
Modeling the anisotropic electro-optic interaction in hybrid silicon-ferroelectric optical modulator.
Hu, Xuan; Cueff, Sébastien; Romeo, Pedro Rojo; Orobtchouk, Régis
We present a numerical method to accurately model the electro-optic interaction in anisotropic materials. Specifically, we combine a full-vectorial finite-difference optical mode solver with a radio-frequency solver to analyze the overlap between optical modes and applied electric field. This technique enables a comprehensive understanding on how electro-optic effects modify individual elements in the permittivity tensor of a material. We demonstrate the interest of this approach by designing a modulator that leverages the Pockels effect in a hybrid silicon-BaTiO3 slot waveguide. Optimized optical confinement in the active BaTiO3 layer as well as design of travelling-wave index-matched electrodes is presented. Most importantly, we show that the overall electro-optic modulation is largely governed by off-diagonal elements in the permittivity tensor. As most of active electro-optic materials are anisotropic, this method paves the way to better understand the physics of electro-optic effects and to improve optical modulators. PMID:25835926
Marine atmospheric effects on electro-optical systems performance
NASA Astrophysics Data System (ADS)
Richter, Juergen H.; Hughes, Herbert G.
For the past twelve years, a coordinated tri-service effort has been underway in the United States Department of Defense to provide an atmospheric effects assessment capability for existing and planned electro-optical (E0) systems. This paper reviews the exploratory development effort in the US Navy. A key responsibility for the Navy was the development of marine aerosol models. An initial model, the Navy Aerosol Model (NAN), was developed, tested, and transitioned into LOWTRAN 6. A more comprehensive model, the Navy Oceanic Vertical Aerosol Model (NOVAM), has been formulated and is presently undergoing comprehensive evaluation and testing. Marine aerosols and their extinction properties are only one important factor in EO systems performance assessment. For many EO systems applications, an accurate knowledge of marine background radiances is required in addition to considering the effects of the intervening atmosphere. Accordingly, a capability was developed to estimate the apparent sea surface radiance for different sea states and meteorological conditions. Also, an empirical relationship was developed which directly relates apparent mean sea temperature to calculated mean sky temperature. In situ measurements of relevant environmental parameters are essential for real-time EO systems performance assessment. Direct measurement of slant path extinction would be most desirable. This motivated a careful investigation of lidar (light detection and ranging) techniques including improvements to single-ended lidar profile inversion algorithms and development of new lidar techniques such as double-ended and dual-angle configurations. It was concluded that single-ended, single frequency lidars can not be used to infer slant path extinction with an accuracy necessary to make meaningful performance assessments. Other lidar configurations may find limited application in model validation and research efforts. No technique has emerged yet which could be considered ready for
Pigtailed electro-optic probes for vectorial electric field mapping
NASA Astrophysics Data System (ADS)
Warzecha, Adriana; Gaborit, Gwenaël; Ruaro, Mickael; Duvillaret, Lionel; Lassere, Jean-Louis
Electro-optic measurement (EO) constitutes an efficient technique to characterize electrical (E) fields : indeed, the Pockel's effect properties (linear modification of refractive indices of some non-centrosymetric crystals induced by the E-field)1 leads to a vectorial measurement. Thus, it allows to map the E-field vector and its transient evolution, either in free space or inside guiding structures. Pigtailed EO sensors are naturally becoming a reliable and consistent mean of characterization for many applications, e.g. high power microwaves (HPM), electromagnetic interference (EMI), on chip diagnostic, bio-electromagnetism (e.g. influence of mobile phones on the human body). Even if these non-invasive sensors provide a greater temporal and spatial resolution (femtosecond and sub-millimeter, respectively) than commonly used sensors (antennas, bolometers), it remains temperature dependant and quite low sensitive. EO probes are based on the modification of a laser beam (either its polarization, phase or amplitude) crossing an EO crystal. We demonstrate here the last developments and improvements for EO probes as well as for whole EO setups, exploiting polarization state or amplitude modulation. The sensor is constituted by a polarization maintaining (PM) fiber carrying the beam to the crystal and taking it back once modulated, gradient index lense(s) managing the shape of the beam, half or quarter wave plate controlling the input and output polarizations and a crystal (either anisotropic: LiTaO3, LiNb03, DAST, KTP or isotropic : ZnTe, InP) converting the E-field into a modulation. Our probes are fully dielectric and cylindrically shaped (length ~ 1 cm and diameter ~ 2-3 mm). The setup is made of a 1.5 μm DFB laser, some photodiodes (low and high speed) added with a polarization state analyser arrangement in case of EO probes based on polarization state modulation scheme. The measurement bench is fully automated and compensate/measure the temperature deviation
Electro-Optical Inspection For Tolerance Control As An Integral Part Of A Flexible Machining Cell
NASA Astrophysics Data System (ADS)
Renaud, Blaise
Institut CERAC has been involved in optical metrology and 3-dimensional surface control for the last couple of years. Among the industrial applications considered is the on-line shape evaluation of machined parts within the manufacturing cell. The specific objective is to measure the machining errors and to compare them with the tolerances set by designers. An electro-optical sensing technique has been developed which relies on a projection Moire contouring optical method. A prototype inspection system has been designed, making use of video detection and computer image processing. Moire interferograms are interpreted, and the metrological information automatically retrieved. A structured database can be generated for subsequent data analysis and for real-time closed-loop corrective actions. A real-time kernel embedded into a synchronisation network (Petri-net) for the control of concurrent processes in the Electra-Optical Inspection (E0I) station was realised and implemented in a MODULA-2 program DIN01. The prototype system for on-line automatic tolerance control taking place within a flexible machining cell is described in this paper, together with the fast-prototype synchronisation program.
Superior electro-optic response in multiferroic bismuth ferrite nanoparticle doped nematic liquid crystal device.
Nayek, Prasenjit; Li, Guoqiang
A superior electro-optic (E-O) response has been achieved when multiferroic bismuth ferrite (BiFeO3/BFO) nanoparticles (NPs) were doped in nematic liquid crystal (NLC) host E7 and the LC device was addressed in the large signal regime by an amplitude modulated square wave signal at the frequency of 100 Hz. The optimized concentration of BFO is 0.15 wt%, and the corresponding total optical response time (rise time + decay time) for a 5 μm-thick cell is 2.5 ms for ~7 V(rms). This might be exploited for the construction of adaptive lenses, modulators, displays, and other E-O devices. The possible reason behind the fast response time could be the visco-elastic constant and restoring force imparted by the locally ordered LCs induced by the multiferroic nanoparticles (MNPs). Polarized optical microscopic textural observation shows that the macroscopic dislocation-free excellent contrast have significant impact on improving the image quality and performance of the devices. PMID:26041701
Superior electro-optic response in multiferroic bismuth ferrite nanoparticle doped nematic liquid crystal device
Nayek, Prasenjit; Li, Guoqiang
A superior electro-optic (E-O) response has been achieved when multiferroic bismuth ferrite (BiFeO3/BFO) nanoparticles (NPs) were doped in nematic liquid crystal (NLC) host E7 and the LC device was addressed in the large signal regime by an amplitude modulated square wave signal at the frequency of 100 Hz. The optimized concentration of BFO is 0.15 wt%, and the corresponding total optical response time (rise time + decay time) for a 5 μm-thick cell is 2.5 ms for ~7 Vrms. This might be exploited for the construction of adaptive lenses, modulators, displays, and other E-O devices. The possible reason behind the fast response time could be the visco-elastic constant and restoring force imparted by the locally ordered LCs induced by the multiferroic nanoparticles (MNPs). Polarized optical microscopic textural observation shows that the macroscopic dislocation-free excellent contrast have significant impact on improving the image quality and performance of the devices. PMID:26041701
An investigation of electro-optical 1/f noise reduction in an open-path tunable diode laser spectrometer
NASA Astrophysics Data System (ADS)
Mahdi, Samira A.
A mobile spectrometer system has been designed to scan the near-surface atmosphere for ammonia gas over a wide range of distances (10 m to 1 Km). Since the system is designed for space applications, it needs to be small, light weight, and low power, which dictates the use of relatively low frequency measurement scans. The spectrometer uses a diode laser, which is subject to a large of electro-optical 1/f noise component at these low frequencies. In this work, digital signal processing techniques are developed to reduce the effects of 1/f noise in gas measurements. A Double Fast Fourier Transform-Based Filter (DFFT-BF) method is developed to maximize the measurement sensitivity of a low frequency Tunable Diode Laser Spectrometer (TDLS) system. The 1/f noise spectrum and the uncertainty in the wavelength of the diode laser emission due to 1/f frequency noise is investigated in both simulations and experiments. Also, measurements of ammonia gas using its 1543 nm absorption peak were performed using a sinusoidal waveform to drive the diode laser. A signal processing method is proposed that reduces the effects of electro-optical 1/f noise while keeping the measurement signal relatively constant. Measurements with different modulated waveforms are also examined, including a sawtooth with superimposed sine wave and a sinusoidal wave with a multiple step offset to drive the diode laser. In addition, the system is tested in outdoor measurements of ammonia gas concentrations. The results show that the DFFT-BF method reduces the effects of the 1/f noise in the measurement.
Optical imaging process based on two-dimensional Fourier transform for synthetic aperture imaging ladar
NASA Astrophysics Data System (ADS)
Sun, Zhiwei; Zhi, Ya'nan; Liu, Liren; Sun, Jianfeng; Zhou, Yu; Hou, Peipei
The synthetic aperture imaging ladar (SAIL) systems typically generate large amounts of data difficult to compress with digital method. This paper presents an optical SAIL processor based on compensation of quadratic phase of echo in azimuth direction and two dimensional Fourier transform. The optical processor mainly consists of one phase-only liquid crystal spatial modulator(LCSLM) to load the phase data of target echo and one cylindrical lens to compensate the quadratic phase and one spherical lens to fulfill the task of two dimensional Fourier transform. We show the imaging processing result of practical target echo obtained by a synthetic aperture imaging ladar demonstrator. The optical processor is compact and lightweight and could provide inherent parallel and the speed-of-light computing capability, it has a promising application future especially in onboard and satellite borne SAIL systems.
Optical Fourier techniques for medical image processing and phase contrast imaging
Yelleswarapu, Chandra S.; Kothapalli, Sri-Rajasekhar; Rao, D.V.G.L.N.
This paper briefly reviews the basics of optical Fourier techniques (OFT) and applications for medical image processing as well as phase contrast imaging of live biological specimens. Enhancement of microcalcifications in a mammogram for early diagnosis of breast cancer is the main focus. Various spatial filtering techniques such as conventional 4f filtering using a spatial mask, photoinduced polarization rotation in photosensitive materials, Fourier holography, and nonlinear transmission characteristics of optical materials are discussed for processing mammograms. We also reviewed how the intensity dependent refractive index can be exploited as a phase filter for phase contrast imaging with a coherent source. This novel approach represents a significant advance in phase contrast microscopy. PMID:18458764
Optical Fourier techniques for medical image processing and phase contrast imaging.
Yelleswarapu, Chandra S; Kothapalli, Sri-Rajasekhar; Rao, D V G L N
This paper briefly reviews the basics of optical Fourier techniques (OFT) and applications for medical image processing as well as phase contrast imaging of live biological specimens. Enhancement of microcalcifications in a mammogram for early diagnosis of breast cancer is the main focus. Various spatial filtering techniques such as conventional 4f filtering using a spatial mask, photoinduced polarization rotation in photosensitive materials, Fourier holography, and nonlinear transmission characteristics of optical materials are discussed for processing mammograms. We also reviewed how the intensity dependent refractive index can be exploited as a phase filter for phase contrast imaging with a coherent source. This novel approach represents a significant advance in phase contrast microscopy. PMID:18458764
Geostationary Imaging Fourier Transform Spectrometer (GIFTS): science applications
NASA Astrophysics Data System (ADS)
Smith, W. L.; Revercomb, H. E.; Zhou, D. K.; Bingham, G. E.; Feltz, W. F.; Huang, H. L.; Knuteson, R. O.; Larar, A. M.; Liu, X.; Reisse, R.; Tobin, D. C.
A revolutionary satellite weather forecasting instrument, called the "GIFTS" which stands for the "Geostationary Imaging Fourier Transform Spectrometer", was recently completed and successfully tested in a space chamber at the Utah State University's Space Dynamics Laboratory. The GIFTS was originally proposed by the NASA Langley Research Center, the University of Wisconsin, and the Utah State University and selected for flight demonstration as NASA's New Millennium Program (NMP) Earth Observing-3 (EO-3) mission, which was unfortunately cancelled in 2004. GIFTS is like a digital 3-d movie camera that, when mounted on a geostationary satellite, would provide from space a revolutionary four-dimensional view of the Earth's atmosphere. GIFTS will measure the distribution, change, and movement of atmospheric moisture, temperature, and certain pollutant gases, such as carbon monoxide and ozone. The observation of the convergence of invisible water vapor, and the change of atmospheric temperature, provides meteorologists with the observations needed to predict where, and when, severe thunderstorms, and possibly tornados, would occur, before they are visible on radar or in satellite cloud imagery. The ability of GIFTS to observe the motion of moisture and clouds at different altitudes enables atmospheric winds to be observed over vast, and otherwise data sparse, oceanic regions of the globe. These wind observations would provide the means to greatly improve the forecast of where tropical storms and hurricanes will move and where and when they will come ashore (i.e., their landfall position and time). GIFTS, if flown into geostationary orbit, would provide about 80,000 vertical profiles per minute, each one like a low vertical resolution (1-2km) weather balloon sounding, but with a spacing of 4 km. GIFTS is a revolutionary atmospheric sensing tool. A glimpse of the science measurement capabilities of GIFTS is provided through airborne measurements with the NPOESS Airborne
Imaging the sun in hard x rays using Fourier telescopes
NASA Technical Reports Server (NTRS)
Campbell, J. W.
For several years, solar flares have been observed with a variety of instruments confirming that tremendous amounts of energy are locally stored in the solar magnetic field and then rapidly released during the life of the flare. In concert with observations, theorists have attempted to describe the means by which these energetic events occur and evolve. Two competing theories have emerged and have stood the test of time. One theory describes the flare in terms of nonthermal, electron beam injection into a thick target while the other uses a thermal approach. Both theories provide results which are reasonably consistent with current observations; but to date, none have been able to provide conclusive evidence as to the validity of either model. Imaging on short time scales (1 s) and/or small size scales (1 arc s) should give definitive answers to these questions. In order to test whether a realistic telescope can indeed discriminate between models, we construct model sources based upon the thermal and the nonthermal models and calculate the emission as a function of time and energy in the range from 10 to 100 keV. In addition, we construct model telescopes representing both the spatial modulation collimator (SMC) and the rotating modulation collimator (RMC) techniques of observation using random photon counting statistics. With these two types of telescopes we numerically simulate the instrument response to the above two model flares to see if there are distinct x-ray signatures which may be discernable. We find that theoretical descriptions of the primary models of solar flares do indeed predict different hard x-ray signatures for 1 sec time scales and at 1-5 arc sec spatial resolution. However, these distinguishing signatures can best be observed early in the impulsive phase and from a position perpendicular to the plane of the loop. Furthermore, we find that Fourier telescopes with reasonable and currently attainable design characteristics can image these
Electro-optic bypass exchange switch integrated in a single LiNbO3 crystal
NASA Astrophysics Data System (ADS)
Song, Zhe; Liu, Liren; Ren, Haixia; Luan, Zhu
In this paper, an electro-optic bypass-exchange switch integrated in a single substrate of birefringent LiNbO3 crystal is proposed, which consists of two beam splitters based on the double refraction on the interfaces and in between an electro-optic modulator using the electro-optic effect of the crystal. Two basic configurations are discussed. In addition, a single-block integrated array of bypass-exchange switches is suggested. These switches have the advantages of small loss, relaxation of the requirement for alignment and low sensitivity to the environment. A design of a single-substrate bypass-exchange switch is given and the experiment is demonstrated, too.
Diffraction from tunable periodic structures: application for the determination of electro-optic coefficients.
Yang, X; Wood, L T; Miller, J H
We discuss a method for measuring electro-optic coefficients by measuring diffraction from a tunable grating. The method involves measuring the changes in the diffraction pattern of a reflection grating, where applied electric fields of alternating direction induce changes in the index of refraction through the electro-optic effect. For certain geometries, these applied fields cause period-doubling effects that produce new peaks in the diffraction pattern. Numerically calculated diffraction patterns are presented for the assumptions of both homogeneous and inhomogeneous fields. Peak splitting, as a function of both the number of slits illuminated and the induced change in the index of refraction, is observed and discussed. Finally, the usefulness of our method for the measurement of electro-optic coefficients is discussed. PMID:18364844
Measurement of Sub-Picosecond Electron Bunches via Electro-Optic Sampling of Coherent Transition Radiation
Maxwell, Timothy John
Future collider applications as well as present high-gradient laser plasma wakefield accelerators and free-electron lasers operating with picosecond bunch durations place a higher demand on the time resolution of bunch distribution diagnostics. This demand has led to significant advancements in the field of electro-optic sampling over the past ten years. These methods allow the probing of diagnostic light such as coherent transition radiation or the bunch wakefields with sub-picosecond time resolution. We present results on the single-shot electro-optic spectral decoding of coherent transition radiation from bunches generated at the Fermilab A0 photoinjector laboratory. A longitudinal double-pulse modulation of the electron beam is also realized by transverse beam masking followed by a transverse-to-longitudinal phase-space exchange beamline. Live profile tuning is demonstrated by upstream beam focusing in conjunction with downstream monitoring of single-shot electro-optic spectral decoding of the coherent transition radiation.
Space Qualification Issues in Acousto-optic and Electro-optic Devices
NASA Technical Reports Server (NTRS)
Prasad, Narasimha S.; Taylor, Edward W.; Trivedi, Sudhir; Kutcher, Sue; Soos, Jolanta
Satellite and space-based applications of photonic devices and systems require operational reliability in the harsh environment of space for extended periods of time. This in turn requires every component of the systems and their packaging to meet space qualifications. Acousto- and electro-optical devices form the major components of many current space based optical systems, which is the focus of this paper. The major space qualification issues are related to: mechanical stability, thermal effects and operation of the devices in the naturally occurring space radiation environment. This paper will discuss acousto- and electro-optic materials and devices with respect to their stability against mechanical vibrations, thermal cycling in operating and non-operating conditions and device responses to space ionizing and displacement radiation effects. Selection of suitable materials and packaging to meet space qualification criteria will also be discussed. Finally, a general roadmap for production and testing of acousto- and electro-optic devices will be discussed.
Micro-electro-mechanically tunable metamaterial with enhanced electro-optic performance
Pitchappa, Prakash; Pei Ho, Chong; Lin, Yu-Sheng; Lee, Chengkuo; Kropelnicki, Piotr; Singh, Navab; Huang, Chia-Yi
We experimentally demonstrate a micro-electro-mechanically tunable metamaterial with enhanced electro-optical performance by increasing the number of movable cantilevers in the symmetrical split ring resonator metamaterial unit cell. Simulations were carried out to understand the interaction of the incident terahertz radiation with out-of-plane deforming metamaterial resonator. In order to improve the overall device performance, the number of released cantilever in a unit cell was increased from one to two, and it was seen that the tunable range was doubled and the switching contrast improved by a factor of around five at 0.7 THz. This simple design approach can be adopted for a wide range of high performance electro-optical devices such as continuously tunable filters, modulators, and electro-optic switches to enable future photonic circuit applications.
A magneto-electro-optical effect in a plasmonic nanowire material.
Valente, João; Ou, Jun-Yu; Plum, Eric; Youngs, Ian J; Zheludev, Nikolay I
Electro- and magneto-optical phenomena play key roles in photonic technology enabling light modulators, optical data storage, sensors and numerous spectroscopic techniques. Optical effects, linear and quadratic in external electric and magnetic field are widely known and comprehensively studied. However, optical phenomena that depend on the simultaneous application of external electric and magnetic fields in conventional media are barely detectable and technologically insignificant. Here we report that a large reciprocal magneto-electro-optical effect can be observed in metamaterials. In an artificial chevron nanowire structure fabricated on an elastic nano-membrane, the Lorentz force drives reversible transmission changes on application of a fraction of a volt when the structure is placed in a fraction-of-tesla magnetic field. We show that magneto-electro-optical modulation can be driven to hundreds of thousands of cycles per second promising applications in magneto-electro-optical modulators and field sensors at nano-tesla levels. PMID:25906761
A magneto-electro-optical effect in a plasmonic nanowire material
NASA Astrophysics Data System (ADS)
Valente, João; Ou, Jun-Yu; Plum, Eric; Youngs, Ian J.; Zheludev, Nikolay I.
Electro- and magneto-optical phenomena play key roles in photonic technology enabling light modulators, optical data storage, sensors and numerous spectroscopic techniques. Optical effects, linear and quadratic in external electric and magnetic field are widely known and comprehensively studied. However, optical phenomena that depend on the simultaneous application of external electric and magnetic fields in conventional media are barely detectable and technologically insignificant. Here we report that a large reciprocal magneto-electro-optical effect can be observed in metamaterials. In an artificial chevron nanowire structure fabricated on an elastic nano-membrane, the Lorentz force drives reversible transmission changes on application of a fraction of a volt when the structure is placed in a fraction-of-tesla magnetic field. We show that magneto-electro-optical modulation can be driven to hundreds of thousands of cycles per second promising applications in magneto-electro-optical modulators and field sensors at nano-tesla levels.
A magneto-electro-optical effect in a plasmonic nanowire material
Valente, João; Ou, Jun-Yu; Plum, Eric; Youngs, Ian J.; Zheludev, Nikolay I.
Electro- and magneto-optical phenomena play key roles in photonic technology enabling light modulators, optical data storage, sensors and numerous spectroscopic techniques. Optical effects, linear and quadratic in external electric and magnetic field are widely known and comprehensively studied. However, optical phenomena that depend on the simultaneous application of external electric and magnetic fields in conventional media are barely detectable and technologically insignificant. Here we report that a large reciprocal magneto-electro-optical effect can be observed in metamaterials. In an artificial chevron nanowire structure fabricated on an elastic nano-membrane, the Lorentz force drives reversible transmission changes on application of a fraction of a volt when the structure is placed in a fraction-of-tesla magnetic field. We show that magneto-electro-optical modulation can be driven to hundreds of thousands of cycles per second promising applications in magneto-electro-optical modulators and field sensors at nano-tesla levels. PMID:25906761
Molecular engineering of nanoscale order in organic electro-optic glasses
Hammond, Scott R.; Sinness, Jessica; Dubbury, Sara; Firestone, Kimberly A.; Benedict, Jason B.; Wawrzak, Zdzislaw; Clot, Olivier; Reid, Philip J.; Dalton, Larry R.
The rational design of bulk nanoscale order in organic electro-optic materials, where the strong dipole-dipole interactions tend to dominate over the weaker forces exploited for self-assembly processes, remains an attractive yet elusive goal. Towards this end, a series of pseudo-discotic dipolar nonlinear optical chromophores have been synthesized and fully characterized. Theoretical guidance and an iterative molecular design process have succeeded in engineering long-range nanoscale order in organic electro-optic glasses. Small-angle thin-film X-ray diffraction experiments demonstrate a self-assembled lamellar morphology in a majority of these materials. Cryogenic crystallography, using a synchrotron X-ray source, afforded the structure of a representative system. This structure, in concert with thin-film X-ray diffraction, atomic force microscopy, UV-vis-NIR absorption spectroscopy, and refractive index experiments elucidated the nanoscale order in the films. Application of these materials in electro-optics is discussed.
A Community Format for Electro-Optical Space Situational Awareness (EOSSA) Data Products
NASA Astrophysics Data System (ADS)
Payne, T.; Mutschler, S.; Meiser, D.; Crespo, R.; Shine, N.
In this paper, we present a flexible format for compiling radiometry/photometry data with pertinent information about the collections into a file for use by the Space Situational Awareness (SSA) community. With the increase in the number of Electro-Optical (EO) sensors collecting photometric, radiometric, and spectroscopic data on man-made Resident Space Objects (RSOs) for SSA purposes, the EO SSA community of interest and stakeholders in SSA require a file format protocol for reporting the extracted information used for SSA from these datasets. This EOSSA file format provides a foundation to enable data providers to format their processed data. The objective of this format is to handle a variety of photometric measurements from multiple sensors and provide fields for specific parameters containing crucial data about the object, the sensor, the collection, and the processing. The chosen formatting type for EOSSA is the Flexible Image Transport System (FITS). It is maintained by the International Astronomical Union and NASA/GSFC. FITS is the standard data format used in astronomy and has extensions and features that make it easy to transport and archive large scientific data sets. There are types of FITS files for multi-dimensional arrays, such as images, or hyperspectral image cubes, and headers and tables for data extracted from the images, and descriptive information about the data and sensor. The FITS binary table extension is the most efficient data structure to use for the purposes of SSA with respect to ease of programming, computational speed, and storage space. A hierarchical data format (HDF5) has many of these features; however, its biggest drawback to our purpose is that the files are large and require a lot of storage space. Secondly, no standardized HDF5 file structure has been developed and there is no high level application programming interface (API).
Fourier transform image processing techniques for grid-based phase contrast imaging
NASA Astrophysics Data System (ADS)
Tahir, Sajjad; Bashir, Sajid; Petruccelli, Jonathan C.; MacDonald, C. A.
A recently developed technique for phase imaging using table top sources is to use multiple fine-pitch gratings. However, the strict manufacturing tolerences and precise alignment required have limited the widespread adoption of grating-based techniques. In this work, we employ a technique recently demonstrated by Bennett et al.1 that ultilizes a single grid of much coarser pitch. Phase is extracted using Fourier processing on a single raw image taken using a focused mammography grid. The effects on the final image of varying grid, object, and detector distances, window widths, and of a variety of windowing functions, used to separate the harmonics, were investigated.
Rotational-translational fourier imaging system requiring only one grid pair
NASA Technical Reports Server (NTRS)
Campbell, Jonathan W. (Inventor)
The sky contains many active sources that emit X-rays, gamma rays, and neutrons. Unfortunately hard X-rays, gamma rays, and neutrons cannot be imaged by conventional optics. This obstacle led to the development of Fourier imaging systems. In early approaches, multiple grid pairs were necessary in order to create rudimentary Fourier imaging systems. At least one set of grid pairs was required to provide multiple real components of a Fourier derived image, and another set was required to provide multiple imaginary components of the image. It has long been recognized that the expense associated with the physical production of the numerous grid pairs required for Fourier imaging was a drawback. Herein one grid pair (two grids), with accompanying rotation and translation, can be used if one grid has one more slit than the other grid, and if the detector is modified.
Silicon-integrated thin-film structure for electro-optic applications
McKee, Rodney A.; Walker, Frederick Joseph
A crystalline thin-film structure suited for use in any of an number of electro-optic applications, such as a phase modulator or a component of an interferometer, includes a semiconductor substrate of silicon and a ferroelectric, optically-clear thin film of the perovskite BaTiO.sub.3 overlying the surface of the silicon substrate. The BaTiO.sub.3 thin film is characterized in that substantially all of the dipole moments associated with the ferroelectric film are arranged substantially parallel to the surface of the substrate to enhance the electro-optic qualities of the film.
Electro-optic architecture for servicing sensors and actuators in advanced aircraft propulsion systems
NASA Technical Reports Server (NTRS)
Poppel, G. L.; Glasheen, W. M.
A detailed design of a fiber optic propulsion control system, integrating favored sensors and electro-optics architecture is presented. Layouts, schematics, and sensor lists describe an advanced fighter engine system model. Components and attributes of candidate fiber optic sensors are identified, and evaluation criteria are used in a trade study resulting in favored sensors for each measurand. System architectural ground rules were applied to accomplish an electro-optics architecture for the favored sensors. A key result was a considerable reduction in signal conductors. Drawings, schematics, specifications, and printed circuit board layouts describe the detailed system design, including application of a planar optical waveguide interface.
Coulomb field strength measurement by electro-optic spectral decoding system at the CALIFES beam line
NASA Astrophysics Data System (ADS)
Pan, R.; Jamison, S. P.; Lefevre, T.; Gillespie, W. A.
Electro-optic (EO) techniques are increasingly used for longitudinal bunch profile measurements. A bunch profile monitor, based on electro-optic spectral decoding (EOSD), has been developed and demonstrated on the CALIFES beam line at CERN. The EO response is analysed using a frequency domain description, and two methods for extraction of absolute Coulomb field strengths from the electron bunch are demonstrated. Measurements at field strengths up to 1.3 MV/m agree with the expectation based on independent charge measurements.
Electric field and temperature measurement using ultra wide bandwidth pigtailed electro-optic probes.
Bernier, Maxime; Gaborit, Gwenaël; Duvillaret, Lionel; Paupert, Alain; Lasserre, Jean-Louis
We present pigtailed electro-optic probes that allow a simultaneous measurement of high frequency electric fields and temperature using a unique laser probe beam. This has been achieved by the development of a novel probe design associated with a fully automated servo-controlled optical bench, initially developed to stabilize the electric field sensor response. The developed electro-optic probes present a stable response in outdoors conditions over a time duration exceeding 1 h, a frequency bandwidth from kHz to tens of GHz with a sensitivity of 0.7 Vm(-1)Hz(-(1/2)), and a temperature accuracy of 40 mK. PMID:18449315
Electro-optic harmonic conversion switch for large-aperture multipass laser systems
Henesian, M.A.; Goldhar, J.; Haas, R.A.
The authors have demonstrated electro-optically tuned second-harmonic generation using Type I KDP inside a plasma-electrode discharge cell. An axial voltage of +/- 52 kV is required to switch a 1.064-..mu..m beam by conversion to 0.53 ..mu..m, in agreement with theory. Electro-optically tuned harmonic generation may be combined with a recently developed transparent plasma electrode to produce a large-aperture switch for multipass laser systems. 7 references, 4 figures, 1 table.
Gahagan, K. T.; Casson, J. L.; Robinson, J. M.; Scymgeour, D. A.; Gopalan, V.; Libatique, N. J; Tafoya, J.; Jain, R.
An electro-optic beam scanner fabricated on ferroelectric LiTaO{sub 3} is demonstrated which is capable of continuously scanning at wavelengths ranging from 0.4-5 {micro}m. The scanning performance varied from a total deflection angle of 13.38{sup o} at 1558 nm to 16.18{sup o} at 632.8 nm. The dispersion of the r{sub 33} and r{sub 13} electro-optic coefficients of LiTaO{sub 3} with wavelength was also determined.
Integration of electro-optic lenses and scanners on ferroelectric LiTaO{sub 3}
Gopalan, V.; Gahagan, K.T.; Jia, Q.X.; Tobinson, J.M.; Mitchell, T.E.; Schlesinger, T.E.; Stancil, D.D.
An integrated electro-optic lens/scanner device was fabricated on a ferroelectric LiTaO{sub 3} wafer. This was done using lithographically defined domain-inverted regions extending through the crystal thickness. A lens power of 0.233 cm{sup {minus}1}kV{sup {minus}1} and a scanner deflection of 12.68 mrad{sup {minus}1}kV{sup {minus}1} was observed. The authors also demonstrate an electro-optic lens stack collimator which collimates an input beam focused to a 5{micro}m waist diameter at {minus}2.3kV.
Midwave infrared imaging Fourier transform spectrometry of combustion plumes
NASA Astrophysics Data System (ADS)
Bradley, Kenneth C.
A midwave infrared (MWIR) imaging Fourier transform spectrometer (IFTS) was used to successfully capture and analyze hyperspectral imagery of combustion plumes. Jet engine exhaust data from a small turbojet engine burning diesel fuel at a low rate of 300 cm3/min was collected at 1 cm -1 resolution from a side-plume vantage point on a 200x64 pixel window at a range of 11.2 meters. Spectral features of H2O, CO, and CO2 were present, and showed spatial variability within the plume structure. An array of thermocouple probes was positioned within the plume to aid in temperature analysis. A single-temperature plume model was implemented to obtain spatially-varying temperatures and plume concentrations. Model-fitted temperatures of 811 +/- 1.5 K and 543 +/- 1.6 K were obtained from plume regions in close proximity to thermocouple probes measuring temperatures of 719 K and 522 K, respectively. Industrial smokestack plume data from a coal-burning stack collected at 0.25 cm-1 resolution at a range of 600 meters featured strong emission from NO, CO, CO2, SO 2, and HCl in the spectral region 1800-3000 cm-1. A simplified radiative transfer model was employed to derive temperature and concentrations for clustered regions of the 128x64 pixel scene, with corresponding statistical error bounds. The hottest region (closest to stack centerline) was 401 +/- 0.36 K, compared to an in-stack measurement of 406 K, and model-derived concentration values of NO, CO2, and SO2 were 140 +/- 1 ppmV, 110,400 +/- 950 ppmV, and 382 +/- 4 ppmV compared to in-stack measurements of 120 ppmV (NOx), 94,000 ppmV, and 382 ppmV, respectively. In-stack measurements of CO and HCl were not provided by the stack operator, but model-derived values of 19 +/- 0.2 ppmV and 111 +/- 1 ppmV are reported near stack centerline. A deployment to Dugway Proving Grounds, UT to collect hyperspectral imagery of chemical and biological threat agent simulants resulted in weak spectral signatures from several species. Plume
Adaptive chirp-Fourier transform for chirp estimation with applications in ISAR imaging of maneuvering targets
NASA Astrophysics Data System (ADS)
Xia, Xiang-Gen; Wang, Genyuan; Chen, Victor C.
This paper first reviews some basic properties of the discrete chirp-Fourier transform and then present an adaptive chirp- Fourier transform, a generalization of the amplitude and phase estimation of sinusoids (APES) algorithm proposed by Li and Stoica for sinusoidal signals. We finally applied it to the ISAR imaging of maneuvering targets.
Method of synthesizing a plurality of reactants and producing thin films of electro-optically active transition metal oxides
Tracy, C. Edwin; Benson, David K.; Ruth, Marta R.
A method of synthesizing electro-optically active reaction products from a plurality of reactants by inducing a reaction by plasma deposition among the reactants. The plasma reaction is effective for consolidating the reactants and producing thin films of electro-optically active transition metal oxides.
Spontaneous helix formation in non-chiral bent-core liquid crystals with fast linear electro-optic effect
Sreenilayam, Sithara P.; Panarin, Yuri P.; Vij, Jagdish K.; Panov, Vitaly P.; Lehmann, Anne; Poppe, Marco; Prehm, Marko; Tschierske, Carsten
Liquid crystals (LCs) represent one of the foundations of modern communication and photonic technologies. Present display technologies are based mainly on nematic LCs, which suffer from limited response time for use in active colour sequential displays and limited image grey scale. Herein we report the first observation of a spontaneously formed helix in a polar tilted smectic LC phase (SmC phase) of achiral bent-core (BC) molecules with the axis of helix lying parallel to the layer normal and a pitch much shorter than the optical wavelength. This new phase shows fast (∼30 μs) grey-scale switching due to the deformation of the helix by the electric field. Even more importantly, defect-free alignment is easily achieved for the first time for a BC mesogen, thus providing potential use in large-scale devices with fast linear and thresholdless electro-optical response. PMID:27156514
Spontaneous helix formation in non-chiral bent-core liquid crystals with fast linear electro-optic effect.
Sreenilayam, Sithara P; Panarin, Yuri P; Vij, Jagdish K; Panov, Vitaly P; Lehmann, Anne; Poppe, Marco; Prehm, Marko; Tschierske, Carsten
Liquid crystals (LCs) represent one of the foundations of modern communication and photonic technologies. Present display technologies are based mainly on nematic LCs, which suffer from limited response time for use in active colour sequential displays and limited image grey scale. Herein we report the first observation of a spontaneously formed helix in a polar tilted smectic LC phase (SmC phase) of achiral bent-core (BC) molecules with the axis of helix lying parallel to the layer normal and a pitch much shorter than the optical wavelength. This new phase shows fast (∼30 μs) grey-scale switching due to the deformation of the helix by the electric field. Even more importantly, defect-free alignment is easily achieved for the first time for a BC mesogen, thus providing potential use in large-scale devices with fast linear and thresholdless electro-optical response. PMID:27156514
Spontaneous helix formation in non-chiral bent-core liquid crystals with fast linear electro-optic effect
NASA Astrophysics Data System (ADS)
Sreenilayam, Sithara P.; Panarin, Yuri P.; Vij, Jagdish K.; Panov, Vitaly P.; Lehmann, Anne; Poppe, Marco; Prehm, Marko; Tschierske, Carsten
Liquid crystals (LCs) represent one of the foundations of modern communication and photonic technologies. Present display technologies are based mainly on nematic LCs, which suffer from limited response time for use in active colour sequential displays and limited image grey scale. Herein we report the first observation of a spontaneously formed helix in a polar tilted smectic LC phase (SmC phase) of achiral bent-core (BC) molecules with the axis of helix lying parallel to the layer normal and a pitch much shorter than the optical wavelength. This new phase shows fast (~30 μs) grey-scale switching due to the deformation of the helix by the electric field. Even more importantly, defect-free alignment is easily achieved for the first time for a BC mesogen, thus providing potential use in large-scale devices with fast linear and thresholdless electro-optical response.
Electro-optical and radar systems for disaster management: lessons and perspectives from India
NASA Astrophysics Data System (ADS)
Hegde, V. S.; Srivastava, S. K.; Bandyopadhayay, S.; Manikiam, B.
Using conjunctively electro-optical and radar systems has been a part of India's Earth Observation (EO) strategy for disaster management. To address the gaps in the operational systems of disaster management, increasingly improved quality of information in terms of spatial scale, temporal scale and all weather capability mapping are called for and the EO satellites have accordingly been configured. For example, CCD camera (1 km spatial resolution) in GEO orbiting INSAT satellites, which work in conjunction with polar orbiting IRS WiFS (188 m spatial resolution) for real time coarse observations of the events such as forest fire, floods etc is in operation. To address the subtle features associated with agricultural drought, Resourcesat has been configured with Advanced WiFS having 55 m spatial, 5 days repetativitity, 740 km swath and 10 bits radiometry. It is a unique mission with variety of payloads viz., AWiFS, LISS 4 (5.8 m multi-spectral; 22 days repetativitity) and PAN from the same platform. The Digital Elevation Models (DEM) emanating from Cartosat are providing valuable inputs to characterize geo-physical terrain vulnerability. Radar Imaging Satellite (RISAT), with all weather capability mission, is yet another mission configured for disaster management. Taking into account the flood dynamics as well as the river basin parameters, RISAST is being configured with multiparametric C-band SAR with 5 imaging modes; 1-2 m spatial resolution; 224 km swath; 7 days repetitivity and 8 bits quantizations. Integrating these capabilities, space based Disaster Management Support (DMS) systems, in India, has been built upon committing EO enabled products and services for disaster reduction on operational basis.
Experimental characterization, evaluation, and diagnosis of advanced hybrid infrared focal plane array electro-optical performance
NASA Astrophysics Data System (ADS)
Lomheim, Terrence S.; Schumann, Lee W.; Kohn, Stanley E.
High performance scanning time-delay-and-integration and staring hybrid focal plane devices with very large formats, small pixel sizes, formidable frame and line rates, on-chip digital programmability, and high dynamic ranges, are being developed for a myriad of defense, civil, and commercial applications that span the spectral range from shortwave infrared (SWIR) to longwave infrared (LWIR). An essential part in the development of such new advanced hybrid infrared focal planes is empirical validation of their electro-optical (EO) performance. Many high-reliability, high-performance applications demand stringent and near flawless EO performance over a wide variety of operating conditions and environments. Verification of focal plane performance compliance over this wide range of parametric conditions requires the development and use of accurate, flexible, and statistically complete test methods and associated equipment. In this paper we review typical focal plane requirements, the ensuing measurement requirements (quantity, accuracy, repeatability, etc.), test methodologies, test equipment requirements, electronics and computer-based data acquisition requirements, statistical data analysis and display requirements, and associated issues. We also discuss special test requirements for verifying the performance of panchromatic thermal and multispectral imaging focal planes where characterization of dynamic modulation transfer function (MTF), and point-image response and optical overload is generally required. We briefly overview focal plane radiation testing. We conclude with a discussion of the technical challenges of characterizing future advanced hybrid focal plane testing where it is anticipated that analog-to- digital conversion will be included directly on focal plane devices, thus creating the scenario of 'photons-in-to-bits- out' within the focal plane itself.
Single-Grid-Pair Fourier Telescope for Imaging in Hard-X Rays and gamma Rays
NASA Technical Reports Server (NTRS)
Campbell, Jonathan
This instrument, a proposed Fourier telescope for imaging in hard-x rays and gamma rays, would contain only one pair of grids made of an appropriate radiation-absorpting/ scattering material, in contradistinction to multiple pairs of such as grids in prior Fourier x- and gamma-ray telescopes. This instrument would also include a relatively coarse gridlike image detector appropriate to the radiant flux to be imaged. Notwithstanding the smaller number of grids and the relative coarseness of the imaging detector, the images produced by the proposed instrument would be of higher quality.
Compact imaging spectrometer combining Fourier transform spectroscopy with a Fabry-Perot interferometer.
Pisani, Marco; Zucco, Massimo
An imaging spectrometer based on a Fabry-Perot interferometer is presented. The Fabry-Perot interferometer scans the mirror distance up to contact and the intensity modulated light signal is transformed using a Fourier Transform based algorithm, as the Michelson based Fourier Transform Spectrometers does. The resulting instrument has the advantage of a compact, high numerical aperture, high luminosity hyperspectral imaging device. Theory of operation is described along with one experimental realization and preliminary results. PMID:19434165
Electro-Optic Modulator Based on Organic Planar Waveguide Integrated with Prism Coupler
NASA Technical Reports Server (NTRS)
Sarkisov, Sergey S.
The objectives of the project, as they were formulated in the proposal, are the following: (1) Design and development of novel electro-optic modulator using single crystalline film of highly efficient electro-optic organic material integrated with prism coupler; (2) Experimental characterization of the figures-of-merit of the modulator. It is expected to perform with an extinction ratio of 10 dB at a driving signal of 5 V; (3) Conclusions on feasibility of the modulator as an element of data communication systems of future generations. The accomplishments of the project are the following: (1) The design of the electro-optic modulator based on a single crystalline film of organic material NPP has been explored; (2) The evaluation of the figures-of-merit of the electro-optic modulator has been performed; (3) Based on the results of characterization of the figures-of-merit, the conclusion was made that the modulator based on a thin film of NPP is feasible and has a great potential of being used in optic communication with a modulation bandwidth of up to 100 GHz and a driving voltage of the order of 3 to 5 V.
Electro-optic phase modulator as a starting mechanism in Ti:sapphire
NASA Astrophysics Data System (ADS)
Grice, Warren P.; Walmsley, Ian A.; Suzuki, Mitsutoshi
An electro-optic phase modulator in a regenerative mode-locker configuration is demonstrated as the starting mechanism for a Kerr-lens mode-locked Ti:sapphire laser. Mode locking is initiated automatically, and the system is capable of pulses as short as 21 fs.
Electro-optic polymer light modulator based on surface plasmon resonance
NASA Astrophysics Data System (ADS)
Jung, C.; Yee, S.; Kuhn, K.
The first experimental results, to our knowledge, for an optical modulator that makes use of an electro-optic polymer located between two thin silver films are presented. The methods used to fabricate the modulator are discussed. Initial results show 18.5% modulation in the intensity of the light reflected off of the modulator at a wavelength of 6328 A.
Analytical study of terahertz wave intensity measurements by ZnTe electro-optic crystal
NASA Astrophysics Data System (ADS)
Siddique, Muhammad; Yang, Suhui; Li, Zhuo; Li, Ping
An analytical study of THz-waves' intensity measurement generated by Terahertz Parametric Oscillator (TPO) and detection of the THz pulses occurs via free-space electro optic detection by ZnTe crystal has been studied. The pump-probe technique has been used to observe the dynamics of an optically excited ZnTe electro-optic crystal. THz wave will be used as modulation source for electro-optical phenomena in ZnTe crystal. The THz pulses generated by TPO are 10-25 ns pulses at a repetition rate of 1Hz. ZnTe crystal is being used for intensity measurement of THz-waves. In this theoretical proposed experiment, a short pump pulse (THz-wave) and probe pulse (near IR laser) with duration of typically 10 to 25 ns interacts in the ZnTe. In electro-optic sampling the two effects namely Pockels effect and Kerr effect have been discussed and interaction of two beams from or transmission through the ZnTe, the probe pulse Intensity contains information about the THz-waves' intensity and so on.
Heterostructure of ferromagnetic and ferroelectric materials with magneto-optic and electro-optic effects
NASA Technical Reports Server (NTRS)
Zou, Yingyin Kevin (Inventor); Jiang, Hua (Inventor); Li, Kewen Kevin (Inventor); Guo, Xiaomei (Inventor)
A heterostructure of multiferroics or magnetoelectrics (ME) was disclosed. The film has both ferromagnetic and ferroelectric properties, as well as magneto-optic (MO) and electro-optic (EO) properties. Oxide buffer layers were employed to allow grown a cracking-free heterostructure a solution coating method.
High-power electro-optic switch technology based on novel transparent ceramic
NASA Astrophysics Data System (ADS)
Xue-Jiao, Zhang; Qing, Ye; Rong-Hui, Qu; Hai-wen, Cai
A novel high-power polarization-independent electro-optic switch technology based on a reciprocal structure Sagnac interferometer and a transparent quadratic electro-optic ceramic is proposed and analyzed theoretically and experimentally. The electro-optic ceramic is used as a phase retarder for the clockwise and counter-clockwise polarized light, and their polarization directions are adjusted to their orthogonal positions by using two half-wave plates. The output light then becomes polarization-independent with respect to the polarization direction of the input light. The switch characteristics, including splitter ratios and polarization states, are theoretically analyzed and simulated in detail by the matrix multiplication method. An experimental setup is built to verify the analysis and experimental results. A new component ceramic is used and a non-polarizing cube beam splitter (NPBS) replaces the beam splitter (BS) to lower the ON/OFF voltage to 305 V and improve the extinction ratio by 2 dB. Finally, the laser-induced damage threshold for the proposed switch is measured and discussed. It is believed that potential applications of this novel polarization-independent electro-optic switch technology will be wide, especially for ultrafast high-power laser systems. Project supported by the National Natural Science Foundation of China (Grant Nos. 61137004, 61405218, and 61535014).
Development of Articulated Competency-Based Curriculum in Laser/Electro-Optics Technology. Final Report.
ERIC Educational Resources Information Center
Luzerne County Community Coll., Nanticoke, PA.
A project was conducted at the Community College of Luzerne County (Pennsylvania) to develop, in cooperation with area vocational-technical schools, the first year of a competency-based curriculum in laser/electro-optics technology. Existing programs were reviewed and private sector input was sought in developing the curriculum and identifying…
Development of Articulated Competency-Based Curriculum in Laser/Electro-Optics Technology. Final Report.
ERIC Educational Resources Information Center
Luzerne County Community Coll., Nanticoke, PA.
The project described in this report was conducted at the Community College of Luzerne County (Pennsylvania) to develop, in conjunction with area vocational-technical schools, the second year of a competency-based curriculum in laser/electro-optics technology. During the project, a task force of teachers from the area schools and the college…
Development of Generalizable Educational Programs in Laser/Electro-Optics Technology: Final Report.
ERIC Educational Resources Information Center
Hull, Daniel M.
The purpose of the Laser/Electro-Optics Technology (LEOT) Project was to establish a pilot educational program, develop a flexible curriculum, prepare and test instructional materials, transport the curriculum and instructional materials into other educational institutions by establishing relevant LEOT programs wherever they are needed, and to…
Giant quadratic electro-optical effect during polarization switching in ultrathin ferroelectric polymer films
Blinov, L. M. Lazarev, V. V.; Palto, S. P.; Yudin, S. G.
The low-frequency quadratic electro-optical effect with a maximum electro-optical coefficient of g = 8 Multiplication-Sign 10{sup -19} m{sup 2}/V{sup 2} (i.e., four orders of magnitude greater than the standard high-frequency value) has been studied in thin films of ferroelectric polymer PVDF(70%)-TrFE(30%). The observed effect is related to the process of spontaneous polarization switching, during which the electron oscillators of C-F and C-H dipole groups rotate to become parallel to the applied field. As a result, the ellipsoid of the refractive index exhibits narrowing in the direction perpendicular to the field. The field dependence of the electro-optical coefficient g correlates with that of the apparent dielectric permittivity, which can be introduced under the condition of ferroelectric polarization switching. The observed electro-optical effect strongly decreases when the frequency increases up to several hundred hertz. The temperature dependence of the effect exhibits clearly pronounced hysteresis in the region of the ferroelectric phase transition.
Quantum calculations of the electro-optical parameters of haloid ethers, esters, amides and carbamates
NASA Astrophysics Data System (ADS)
Furer, V. L.
Force and electro-optical parameters of haloid ethers, esters, amides and carbamates were calculated using the MINDO/3 method. The obtained values of parameters, frequencies and intensities of bands in IR spectra are in good accordance with experiment. The changes of molecular parameters due to the electronic interactions and conformational transitions are discussed.
New concepts of electro-optical light deflection: EO-slab and phased EO-array
NASA Astrophysics Data System (ADS)
Wirth, Volker; Krasnaberski, Alexei; Ivanenko, Mikhail
Deflection and modulation of a laser beam for Q-switching or material processing can be realized in many ways. Today, one task is still the speed of these components. Especially for spatial pulse separation in ultrashort pulse laser applications the deflection must be faster (MHz). Promising solutions are deflectors based on the electro-optic effect.
Electro-optic modulator for infrared laser using gallium arsenide crystal
NASA Technical Reports Server (NTRS)
Walsh, T. E.
Gallium arsenide electro-optic modulator used for infrared lasers has a mica quarter-wave plate and two calcite polarizers to amplitude or phase modulate an infrared laser light source in the wavelength range from 1 to 3 microns. The large single crystal has uniformly high resistivities, is strain free, and comparable in quality to good optical glass.
Polymer stabilized liquid crystals: Topology-mediated electro-optical behavior and applications
NASA Astrophysics Data System (ADS)
Weng, Libo
There has been a wide range of liquid crystal polymer composites that vary in polymer concentration from as little as 3 wt.% (polymer stabilized liquid crystal) to as high as 60 wt.% (polymer dispersed liquid crystals). In this dissertation, an approach of surface polymerization based on a low reactive monomer concentration about 1 wt.% is studied in various liquid crystal operation modes. The first part of dissertation describes the development of a vertical alignment (VA) mode with surface polymer stabilization, and the effects of structure-performance relationship of reactive monomers (RMs) and polymerization conditions on the electro-optical behaviors of the liquid crystal device has been explored. The polymer topography plays an important role in modifying and enhancing the electro-optical performance of stabilized liquid crystal alignment. The enabling surface-pinned polymer stabilized vertical alignment (PSVA) approach has led to the development of high-performance and fast-switching displays with controllable pretilt angle, increase in surface anchoring energy, high optical contrast and fast response time. The second part of the dissertation explores a PSVA mode with in-plane switching (IPS) and its application for high-efficiency and fast-switching phase gratings. The diffraction patterns and the electro-optical behaviors including diffraction efficiency and response time are characterized. The diffraction grating mechanism and performance have been validated by computer simulation. Finally, the advantages of surface polymerization approach such as good optical contrast and fast response time have been applied to the fringe-field switching (FFS) system. The concentration of reactive monomer on the electro-optical behavior of the FFS cells is optimized. The outstanding electro-optical results and mechanism of increase in surface anchoring strength are corroborated by the director field simulation. The density and topology of nanoscale polymer protrusions
A generalized Fourier penalty in prior-image-based reconstruction for cross-platform imaging
NASA Astrophysics Data System (ADS)
Pourmorteza, A.; Siewerdsen, J. H.; Stayman, J. W.
Sequential CT studies present an excellent opportunity to apply prior-image-based reconstruction (PIBR) methods that leverage high-fidelity prior imaging studies to improve image quality and/or reduce x-ray exposure in subsequent studies. One major obstacle in using PIBR is that the initial and subsequent studies are often performed on different scanners (e.g. diagnostic CT followed by CBCT for interventional guidance); this results in mismatch in attenuation values due to hardware and software differences. While improved artifact correction techniques can potentially mitigate such differences, the correction is often incomplete. Here, we present an alternate strategy where the PIBR itself is used to mitigate these differences. We define a new penalty for the previously introduced PIBR called Reconstruction of Difference (RoD). RoD differs from many other PIBRs in that it reconstructs only changes in the anatomy (vs. reconstructing the current anatomy). Direct regularization of the difference image in RoD provides an opportunity to selectively penalize spatial frequencies of the difference image (e.g. low frequency differences associated with attenuation offsets and shading artifacts) without interfering with the variations in unchanged background image. We leverage this flexibility and introduce a novel regularization strategy using a generalized Fourier penalty within the RoD framework and develop the modified reconstruction algorithm. We evaluate the performance of the new approach in both simulation studies and in physical CBCT test-bench data. We find that generalized Fourier penalty can be highly effective in reducing low-frequency x-ray artifacts through selective suppression of spatial frequencies in the reconstructed difference image.
Image watermarking extraction using Fourier domain Wiener filter
NASA Astrophysics Data System (ADS)
Birch, Philip; Pavlidis, Marios; Panwar, Ankit; Nnamadim, Ozoemena; Kypraios, Ioannis; Mitra, Bhargav; Young, Rupert; Chatwin, Chris
Digital watermarking is a vital process for protecting the copyright of images. This paper presents a method of embedding a private robust watermark into a digital image. The full complex form the Wiener filter is used to extract the signal from the watermarked image. This is shown to outperform the more conventional approximate notation. The results are shown to be extremely noise insensitive.
Imaging Organ of Corti Vibration Using Fourier-Domain OCT
NASA Astrophysics Data System (ADS)
Choudhury, Niloy; Chen, Fangyi; Fridberger, Anders; Zha, Dingjun; Jacques, Steven L.; Wang, Ruikang K.; Nuttall, Alfred L.
Measuring the sound stimulated vibration from various structures in the organ of Corti is important in understanding how the small vibrations are amplified and detected. In this study we examine the feasibility of using phase-sensitive Fourier domain optical coherence tomography (PSFD-OCT) to measure vibration of the cellular structures of the organ of Corti. PSFD-OCT is a low coherence interferrometry system where the interferrogram is detected as a function of wavelength. The phase of the Fourier transformation of the detected spectra contains path deference (between the sample arm and the reference arm) information of the interferometer. In PSFD-OCT this phase is measured as a function of time and thus any time dependent change in the path difference between the sample arm and the reference arm can be detected. In the experiment, we used an in vitro preparation of the guinea pig cochlea and made a surgical opening at the apical end to access the organ of Corti. By applying tones with different frequencies via the intact middle ear, we recorded the structural vibration inside the organ of Corti. Vibration amplitude and phase of different substructures were mapped on a cross-section view of the organ of Corti. Although the measurements were made at the apical turn of the cochlea, it will be possible to make vibration measurement from various turns of the cochlea. The noise floor of the system was 0.3 nm, calibrated using a piezo stack as a calibrator.
Tunable microwave bandpass filter integrated power divider based on the high anisotropy electro-optic nematic liquid crystal.
Liu, Yupeng; Liu, Yang; Li, Haiyan; Jiang, Di; Cao, Weiping; Chen, Hui; Xia, Lei; Xu, Ruimin
A novel, compact microwave tunable bandpass filter integrated power divider, based on the high anisotropy electro-optic nematic liquid crystal, is proposed in this letter. Liquid crystal, as the electro-optic material, is placed between top inverted microstrip line and the metal plate. The proposed structure can realize continuous tunable bandpass response and miniaturization. The proposed design concept is validated by the good performance of simulation results and experimental results. The electro-optic material has shown great potential for microwave application. PMID:27475583
Tunable microwave bandpass filter integrated power divider based on the high anisotropy electro-optic nematic liquid crystal
NASA Astrophysics Data System (ADS)
Liu, Yupeng; Liu, Yang; Li, Haiyan; Jiang, Di; Cao, Weiping; Chen, Hui; Xia, Lei; Xu, Ruimin
A novel, compact microwave tunable bandpass filter integrated power divider, based on the high anisotropy electro-optic nematic liquid crystal, is proposed in this letter. Liquid crystal, as the electro-optic material, is placed between top inverted microstrip line and the metal plate. The proposed structure can realize continuous tunable bandpass response and miniaturization. The proposed design concept is validated by the good performance of simulation results and experimental results. The electro-optic material has shown great potential for microwave application.
Applied electro-optics educational and training program with multiple entrance and exit pathways
NASA Astrophysics Data System (ADS)
Scott, Patricia; Zhou, Feng; Zilic, Dorothy
This paper presents an innovative hands-on training program designed to create a pipeline of highly-skilled technical workers for today's workforce economy. The 2+2+2 Pennsylvania Integrated Workforce Leadership Program in Electro-Optics prepares students for a career in this new high-tech field. With seamless transition from high school into college, the program offers the versatility of multiple entrance and exit pathways. After completion of each educational level, students can exit the program with various skill levels, including certificates, an associate's degree, or a bachelor's degree. Launched by Indiana University of Pennsylvania (IUP) in partnership with Lenape Vocational School (Lenape), the 2+2+2 educational pathway program was implemented to promote early training of high-school students. During the first level, students in their junior and/or senior year enroll in four Electro-Optics courses at Lenape. Upon completion of these courses and an Advanced Placement Equivalency course with an appropriate exam score, students can earn a certificate from Lenape for the 15+ credits, which also can be articulated into IUP's associate degree program in Electro-Optics. During the second level, students can earn an associate's degree in Electro-Optics, offered only at the IUP Northpointe Campus. After completion of the Associate in Applied Science (A.A.S.), students are prepared to enter the workforce as senior technicians. During the third level, students who have completed the Associate of Science (A.S.) in Electro-Optics have the opportunity to matriculate at IUP's Indiana Campus to earn a Bachelor of Science (B.S.) degree in Applied Physics with a track in Electro-Optics. Hence, the name 2+2+2 refers to getting started in high school, continuing the educational experience with an associate's degree program, and optionally moving on to a bachelor's degree. Consequently, students move from one educational level to the next with advanced credits toward the next
Periodic artifact reduction in Fourier transforms of full field atomic resolution images.
Hovden, Robert; Jiang, Yi; Xin, Huolin L; Kourkoutis, Lena F
The discrete Fourier transform is among the most routine tools used in high-resolution scanning/transmission electron microscopy (S/TEM). However, when calculating a Fourier transform, periodic boundary conditions are imposed and sharp discontinuities between the edges of an image cause a cross patterned artifact along the reciprocal space axes. This artifact can interfere with the analysis of reciprocal lattice peaks of an atomic resolution image. Here we demonstrate that the recently developed Periodic Plus Smooth Decomposition technique provides a simple, efficient method for reliable removal of artifacts caused by edge discontinuities. In this method, edge artifacts are reduced by subtracting a smooth background that solves Poisson's equation with boundary conditions set by the image's edges. Unlike the traditional windowed Fourier transforms, Periodic Plus Smooth Decomposition maintains sharp reciprocal lattice peaks from the image's entire field of view. PMID:25597865
In vivo human retinal imaging by Fourier domain optical coherence tomography.
Wojtkowski, Maciej; Leitgeb, Rainer; Kowalczyk, Andrzej; Bajraszewski, Tomasz; Fercher, Adolf F
We present what is to our knowledge the first in vivo tomograms of human retina obtained by Fourier domain optical coherence tomography. We would like to show that this technique might be as powerful as other optical coherence tomography techniques in the ophthalmologic imaging field. The method, experimental setup, data processing, and images are discussed. PMID:12175297
Fourier Power Spectrum Characteristics of Face Photographs: Attractiveness Perception Depends on Low-Level Image Properties
Langner, Oliver; Wiese, Holger; Redies, Christoph
We investigated whether low-level processed image properties that are shared by natural scenes and artworks – but not veridical face photographs – affect the perception of facial attractiveness and age. Specifically, we considered the slope of the radially averaged Fourier power spectrum in a log-log plot. This slope is a measure of the distribution of special frequency power in an image. Images of natural scenes and artworks possess – compared to face images – a relatively shallow slope (i.e., increased high spatial frequency power). Since aesthetic perception might be based on the efficient processing of images with natural scene statistics, we assumed that the perception of facial attractiveness might also be affected by these properties. We calculated Fourier slope and other beauty-associated measurements in face images and correlated them with ratings of attractiveness and age of the depicted persons (Study 1). We found that Fourier slope – in contrast to the other tested image properties – did not predict attractiveness ratings when we controlled for age. In Study 2A, we overlaid face images with random-phase patterns with different statistics. Patterns with a slope similar to those in natural scenes and artworks resulted in lower attractiveness and higher age ratings. In Studies 2B and 2C, we directly manipulated the Fourier slope of face images and found that images with shallower slopes were rated as more attractive. Additionally, attractiveness of unaltered faces was affected by the Fourier slope of a random-phase background (Study 3). Faces in front of backgrounds with statistics similar to natural scenes and faces were rated as more attractive. We conclude that facial attractiveness ratings are affected by specific image properties. An explanation might be the efficient coding hypothesis. PMID:25835539
Integrated photoelasticity through imaging fourier polarimetry of an elliptic retarder.
Berezhna, S; Berezhnyy, I; Takashi, M
It is shown that three optical parameters that are necessary for stress computation in integrated photoelasticity can be measured with high accuracy by use of a Fourier polarimetry method. Inasmuch as a photoelastic sample, which is an object of investigation in integrated photoelasticity, is a kind of an elliptic retarder, the technique presented here measures relative retardation delta, azimuth angle theta, and ellipticity angle epsilon instead of the characteristic parameters that traditionally have been used in integrated photoelasticity. The ability of the new technique to provide better accuracy with a simpler setup has been proved experimentally. Furthermore, the technique is self-contained as for phase measurement; i.e., it automatically performs phase unwrapping at the points where phase data exceed the value of pi. The full value of a phase at a certain point is retrieved by processing of pi-modulo phase data that have been precisely measured at several wavelengths. The usefulness of the new method for integrated photoelasticity has been demonstrated through measurement of a diametrically compressed disk viewed at oblique light incidence. PMID:18357041
Effect of solvents on the electro-optical switching of graphene oxide dispersions
NASA Astrophysics Data System (ADS)
Ahmad, Rana Tariq Mehmood; Hong, Seung-Ho; Shen, Tian-Zi; Masud, Aurangzeb Rashid; Song, Jang-Kun
The electrical manipulation of graphene oxide (GO) alignment in aqueous dispersions is a useful technique with various applications. In particular, the electrical switching of GO particles can be used to devise optical birefringent liquid crystal displays. However, the electric switching of aqueous GO dispersions with a high ionic concentration requires driving voltages with high frequencies (˜10 kHz), which is a challenging limitation. We demonstrate that stable electro-optical switching can be achieved at low frequencies (100 Hz) using GO dispersions in organic solvents instead of water. The hydrodynamic flow of the solvent and the electrophoretic drift of the GO particles are hindered in the GO dispersions in organic solvents with lower dielectric constants. Moreover, the electro-optical performance of these GO dispersions is similar to the aqueous GO dispersions, despite the lower magnitude of the ionization ratio for the GO particle functional groups. These results are crucial for developing a liquid crystal display device using GO dispersions.
Electro-optic tuning and sidelobe control in acousto-optic tunable filters
NASA Astrophysics Data System (ADS)
Aronson, L. B.
Both the center wavelength and the sidelobe structure of an integrated acousto-optic tunable filter (AOTF) are determined by the effective waveguide birefringence along the length of the device. By altering the birefringence by means of the electro-optic effect, one can control these device characteristics in potentially useful ways. Electro-optic tuning of the center frequency of an AOTF is demonstrated, and it is shown that this tuning mode, while limited to smaller ranges than acoustic frequency tuning, is many orders of magnitude faster. By use of multisection electrodes, dynamic control over the shape of the filter function is demonstrated. Finally, a number of practical uses of this technique are discussed.
Lithium niobate nanoparticle-coated Y-coupler optical fiber for enhanced electro-optic sensitivity.
Rao, Ch N; Sagar, S B; Harshitha, N G; Aepuru, Radhamanohar; Premkumar, S; Panda, H S; Choubey, R K; Kale, S N
Single crystals of lithium niobate (LiNbO3), possessing high birefringence and anisotropic properties have been explored, for a long time, to harness their excellent electro-optic properties. However, their nanoforms are comparatively less explored. In this context, dielectric constant and polarization (P) versus electric-field (E) characteristics of LiNbO3 nanomaterials have been studied. A nonideal P-E loop and a dielectric constant of 20 at the onset of 1 kHz were seen. The electro-optic sensitivity was found to be 4 times as compared to the bulk LiNbO3 crystals. The results are attributed to oxygen vacancies, antisite defects, and grain boundary effects in an already congruent structural matrix of LiNbO3. PMID:25680132
Effect of dielectric claddings on the electro-optic behavior of silicon waveguides.
Sharma, Rajat; Puckett, Matthew W; Lin, Hung-Hsi; Isichenko, Andrei; Vallini, Felipe; Fainman, Yeshaiahu
We fabricate silicon waveguides in silicon-on-insulator (SOI) wafers clad with either silicon dioxide, silicon nitride, or aluminum oxide and, by measuring their electro-optic behavior, we characterize the capacitively induced free-carrier effect. By comparing our results with simulations, we confirm that the observed voltage dependences of the transmission spectra are due to changes in the concentrations of holes and electrons within the semiconductor waveguides and show how strongly these effects depend on the cladding material that comes into contact with the waveguide. Waveguide loss is additionally found to have a high sensitivity to the applied voltage, suggesting that these effects may find use in applications that require low- or high-loss propagation. These phenomena, which are present in all semiconductor waveguides, may be incorporated into more complex waveguide designs in the future to create high-efficiency electro-optic modulators and wavemixers. PMID:26977665
Strong free-carrier electro-optic response of sputtered ZnO films
Dominici, Lorenzo; Michelotti, Francesco; Auf der Maur, Matthias
We report on the anisotropic electro-optic response of sputtered ZnO films and its dispersion towards both the frequency of the modulating voltage and the wavelength of the probing beam. The observed dispersion put in evidence two mechanisms. A fast and weak electrorefraction response, due to the nonlinear polarization of bound electrons, and a strong and slow carrier refraction term, ascribed to the modulation of free carriers. The former corresponds to an electro-optical coefficient of approximately -0.5 pm/V, while the latter may reach a magnitude up to 20 times stronger. This term relaxes at about 12 kHz and is largely wavelength dependent, due to a combination of effects. Also bias voltages lead to its quenching, likely extending the depletion regions at grain boundaries.
Wireless electro-optic switching network for optical fiber sensor array using MEMS-IDT devices
NASA Astrophysics Data System (ADS)
Varadan, Vijay K.; Varadan, Vasundara V.
Optical fiber arrays have been proposed for signal paths in various civilian and military controls as a means of offering advanced sensing functions not available in electronic systems. To implement optic fiber sensors on various control systems, a proper electro-optic architecture (EOA) with a bar- coded electro-optical switch needs to be studied. In this paper, a design of such EO switch is proposed which can be operated remotely. Lithium Niobate is chosen as the EO material. The MEMS-IDT device is designed with Lithium Niobate as a substrate with IDT and a set of floating reflectors. The reflectors can be programmable and thus a bar-coded switch can be fabricated. The electrostatic field between the reflectors and the Lithium Niobate serves as the fast acting switch in this application.
Electro-optically tunable, multi-wavelength optical parametric generators in aperiodically poled lithium niobates.
Chen, Y H; Chung, H P; Chang, W K; Lyu, H T; Chang, J W; Tseng, C H
We report on the design and demonstration of electro-optically tunable, multi-wavelength optical parametric generators (OPGs) based on aperiodically poled lithium niobate (APPLN) crystals. Two methods have been proposed to significantly enhance the electro-optic (EO) tunability of an APPLN OPG constructed by the aperiodic optical superlattice (AOS) technique. This is done by engineering the APPLN domain structure either in the crystal fabrication or in the crystal design process to increase the length or block-number difference of the two opposite-polarity domains used in the structure. Several orders of magnitude enhancement on the EO tuning rate of the APPLN OPGs constructed by the proposed techniques for simultaneous multiple signal wavelength generation over a conventional one has been demonstrated in a near infrared band (1500-1600 nm). PMID:23263140
Paraxial Theory of Direct Electro-optic Sampling of the Quantum Vacuum.
Moskalenko, A S; Riek, C; Seletskiy, D V; Burkard, G; Leitenstorfer, A
Direct detection of vacuum fluctuations and analysis of subcycle quantum properties of the electric field are explored by a paraxial quantum theory of ultrafast electro-optic sampling. The feasibility of such experiments is demonstrated by realistic calculations adopting a thin ZnTe electro-optic crystal and stable few-femtosecond laser pulses. We show that nonlinear mixing of a short near-infrared probe pulse with the multiterahertz vacuum field leads to an increase of the signal variance with respect to the shot noise level. The vacuum contribution increases significantly for appropriate length of the nonlinear crystal, short pulse duration, tight focusing, and a sufficiently large number of photons per probe pulse. If the vacuum input is squeezed, the signal variance depends on the probe delay. Temporal positions with a noise level below the pure vacuum may be traced with subcycle resolution. PMID:26764990
Electro-optical co-simulation for integrated CMOS photonic circuits with VerilogA.
Sorace-Agaskar, Cheryl; Leu, Jonathan; Watts, Michael R; Stojanovic, Vladimir
We present a Cadence toolkit library written in VerilogA for simulation of electro-optical systems. We have identified and described a set of fundamental photonic components at the physical level such that characteristics of composite devices (e.g. ring modulators) are created organically - by simple instantiation of fundamental primitives. Both the amplitude and phase of optical signals as well as optical-electrical interactions are simulated. We show that the results match other simulations and analytic solutions that have previously been compared to theory for both simple devices, such as ring resonators, and more complicated devices and systems such as single-sideband modulators, WDM links and Pound Drever Hall Locking loops. We also illustrate the capability of such toolkit for co-simulation with electronic circuits, which is a key enabler of the electro-optic system development and verification. PMID:26480379
High-speed and low-power electro-optical DSP coprocessor.
Tamir, Dan E; Shaked, Natan T; Wilson, Peter J; Dolev, Shlomi
A fast, power-efficient electro-optical vector-by-matrix multiplier (VMM) architecture is presented. Careful design of an electrical unit supporting high-speed data transfer enables this architecture to overcome bottlenecks encountered by previous VMM architectures. Based on the proposed architecture, we present an electro-optical digital signal processing (DSP) coprocessor that can achieve a significant speedup of 2-3 orders of magnitude over existing DSP technologies and execute more than 16 teraflops. We show that it is feasible to implement the system using off-the-shelf components, analyze the performance of the architecture with respect to primitive DSP operations, and detail the use of the new architecture for several DSP applications. PMID:19649106
Nanosecond square high voltage pulse generator for electro-optic switch
NASA Astrophysics Data System (ADS)
Feng, Xian-wang; Long, Xing-wu; Tan, Zhong-qi
A scalable square high voltage pulse generator, which has the properties of fast rise time, fast fall time, powerful driving capability, and long lifetime, is presented in this paper by utilizing solid state circuitry. A totem-pole topology is designed to supply a powerful driving capability for the electro-optic (EO) crystal which is of capacitive load. Power MOSFETs are configured in series to sustain high voltage, and proper driving circuits are introduced for the specific MOSFETs configurations. A 3000 V pulse generator with ˜49.04 ns rise time and ˜10.40 ns fall time of the output waveform is presented. This kind of generator is desirable for electro-optic switch. However, it is not specific to EO switch and may have broad applications where high voltage fast switching is required.
Nanosecond square high voltage pulse generator for electro-optic switch.
Feng, Xian-wang; Long, Xing-wu; Tan, Zhong-qi
A scalable square high voltage pulse generator, which has the properties of fast rise time, fast fall time, powerful driving capability, and long lifetime, is presented in this paper by utilizing solid state circuitry. A totem-pole topology is designed to supply a powerful driving capability for the electro-optic (EO) crystal which is of capacitive load. Power MOSFETs are configured in series to sustain high voltage, and proper driving circuits are introduced for the specific MOSFETs configurations. A 3000 V pulse generator with ~49.04 ns rise time and ~10.40 ns fall time of the output waveform is presented. This kind of generator is desirable for electro-optic switch. However, it is not specific to EO switch and may have broad applications where high voltage fast switching is required. PMID:21806222
Recent Advances in the Design of Electro-Optic Sensors for Minimally Destructive Microwave Field Probing
Lee, Dong-Joon; Kang, No-Weon; Choi, Jun-Ho; Kim, Junyeon; Whitaker, John F.
In this paper we review recent design methodologies for fully dielectric electro-optic sensors that have applications in non-destructive evaluation (NDE) of devices and materials that radiate, guide, or otherwise may be impacted by microwave fields. In many practical NDE situations, fiber-coupled-sensor configurations are preferred due to their advantages over free-space bulk sensors in terms of optical alignment, spatial resolution, and especially, a low degree of field invasiveness. We propose and review five distinct types of fiber-coupled electro-optic sensor probes. The design guidelines for each probe type and their performances in absolute electric-field measurements are compared and summarized. PMID:22346604
Adjustable mount for electro-optic transducers in an evacuated cryogenic system
NASA Technical Reports Server (NTRS)
Crossley, Edward A., Jr. (Inventor); Haynes, David P. (Inventor); Jones, Howard C. (Inventor); Jones, Irby W. (Inventor)
The invention is an adjustable mount for positioning an electro-optic transducer in an evacuated cryogenic environment. Electro-optic transducers are used in this manner as high sensitivity detectors of gas emission lines of spectroscopic analysis. The mount is made up of an adjusting mechanism and a transducer mount. The adjusting mechanism provided five degrees of freedom, linear adjustments and angular adjustments. The mount allows the use of an internal lens to focus energy on the transducer element thereby improving the efficiency of the detection device. Further, the transducer mount, although attached to the adjusting mechanism, is isolated thermally such that a cryogenic environment can be maintained at the transducer while the adjusting mechanism remains at room temperature. Radiation shields also are incorporated to further reduce heat flow to the transducer location.
Time evolution of an electro-optic modulator by detection of its nonlinear behavior
NASA Astrophysics Data System (ADS)
Bui, Dang Thanh; Nguyen, Lam Duy; Ledoux-Rak, Isabelle; Journet, Bernard
The stability of an electro-optic modulator has been significantly improved by implementing an original temperature control system. In particular, the evolution of the modulator characteristics can be followed through its nonlinear behavior by detecting the second harmonic of a low-frequency modulation signal; the evolution can be investigated with a higher accuracy by measuring also the phase-shift of this harmonic signal. Two digital boards have been developed with PSOC microcontrollers. The first one is associated with a small power amplifier for the temperature control; the second board is used to analyze the behavior of the electro-optic modulator. By thermal control of the modulator it is possible to reduce significantly the drift of its optical bias point.
Method of synthesizing a plurality of reactants and producing thin films of electro-optically active transition metal oxides
Tracy, C.E.; Benson, D.K.; Ruth, M.R.
A method of synthesizing a plurality of reactants by inducing a reaction by plasma deposition among the reactants. The plasma reaction is effective for consolidating the reactants and producing thin films of electro-optically active transition metal oxides.
Electro-optic MZI modulators, utilizing different phases in proton-exchanged LiTaO3 waveguides
NASA Astrophysics Data System (ADS)
Kostritskii, S. M.; Korkishko, Yu. N.; Fedorov, V. A.; Tavlykaev, R. F.; Ramaswamy, R. V.
Electro-optic Mach-Zehnder interferometric (MZI) modulators have been fabricated by proton exchange in LiTaO3. Electro-optic efficiency of these modulators has been found to be depending on phase composition of HxLi1-xTaO3 waveguide in full accordance with the data of Raman scattering spectroscopy on microscopic contributions in electro-optic effect for the different HxLi1-xTaO3 phases. These spectroscopy data were used to found an appropriate phase composition and, thus, optimize MZI modulators. The experimental samples of MZI modulator fabricated at the optimal technological conditions exhibit the improved electro-optical efficiency with far superior photorefractive resistance compared to the LiNbO3 waveguides and modulators.
Proposed measurement of spin currents in a GaAs crystal using the electro-optical Pockels effect
Zhang, Xingchu; Zheng, Yongjun; She, Weilong
A new method for measuring spin currents is proposed, based on the linear electro-optic (Pockels) effect caused by the additional second-order nonlinear electric susceptibility (electro-optic tensor) generated by the spin currents. The non-zero elements of electro-optic tensor induced by spin currents in GaAs crystal are calculated, and the wave coupling theory of linear electro-optic effect is used to analyze the polarization change of a probe beam. The numerical results show that, for a linearly polarized probe beam with a frequency close to the band gap of GaAs crystal, its polarization rotation can be as large as 14 μrad under an applied electric field of about 350 V/mm. This effect should offer an alternative detection method for spintronics.
Active mode-locked lasers and other photonic devices using electro-optic whispering gallery mode resonators
NASA Technical Reports Server (NTRS)
Matsko, Andrey B. (Inventor); Ilchenko, Vladimir (Inventor); Savchenkov, Anatoliy (Inventor); Maleki, Lutfollah (Inventor)
Techniques and devices using whispering gallery mode (WGM) optical resonators, where the optical materials of the WGM resonators exhibit an electro-optical effect to perform optical modulation. Examples of actively mode-locked lasers and other devices are described.
Triggerable electro-optic amplitude modulator bias stabilizer for integrated optical devices
Conder, A.D.; Haigh, R.E.; Hugenberg, K.F.
An improved Mach-Zehnder integrated optical electro-optic modulator is achieved by application and incorporation of a DC bias box containing a laser synchronized trigger circuit, a DC ramp and hold circuit, a modulator transfer function negative peak detector circuit, and an adjustable delay circuit. The DC bias box ramps the DC bias along the transfer function curve to any desired phase or point of operation at which point the RF modulation takes place. 7 figs.
Triggerable electro-optic amplitude modulator bias stabilizer for integrated optical devices
Conder, Alan D.; Haigh, Ronald E.; Hugenberg, Keith F.
An improved Mach-Zehnder integrated optical electro-optic modulator is achieved by application and incorporation of a DC bias box containing a laser synchronized trigger circuit, a DC ramp and hold circuit, a modulator transfer function negative peak detector circuit, and an adjustable delay circuit. The DC bias box ramps the DC bias along the transfer function curve to any desired phase or point of operation at which point the RF modulation takes place.
Measurement of strains at high temperatures by means of electro-optics holography
NASA Technical Reports Server (NTRS)
Sciammarella, Cesar A.; Bhat, G.; Vaitekunas, Jeffrey
Electro-optics holographic-moire interferometry is used to measure strains at temperatures up to 1000 C. A description of the instrumentation developed to carry out the measurements is given. The data processing technique is also explained. Main problems encountered in recording patterns at high temperatures are analyzed and possible solutions are outlined. Optical results are compared with strain gage values obtained with instrumented specimens and with theoretical results. Very good agreement is found between optical, strain gage and theoretical results.
Electro-optical control in a plasmonic metamaterial hybridised with a liquid-crystal cell.
Buchnev, O; Ou, J Y; Kaczmarek, M; Zheludev, N I; Fedotov, V A
We experimentally demonstrate efficient electro-optical control in an active nano-structured plasmonic metamaterial hybridised with a liquid-crystal cell. The hybridisation was achieved by simultaneously replacing the polarizer, transparent electrode and molecular alignment layer of the liquid-crystal cell with the metamaterial nano-structure. With the control signal of only 7 V we have achieved a fivefold hysteresis-free modulation of metamaterial transmission at the wavelength of 1.55 µm. PMID:23389148
Electro-Optic Segment-Segment Sensors for Radio and Optical Telescopes
NASA Technical Reports Server (NTRS)
Abramovici, Alex
A document discusses an electro-optic sensor that consists of a collimator, attached to one segment, and a quad diode, attached to an adjacent segment. Relative segment-segment motion causes the beam from the collimator to move across the quad diode, thus generating a measureable electric signal. This sensor type, which is relatively inexpensive, can be configured as an edge sensor, or as a remote segment-segment motion sensor.
Measurement of Electro-Optic Shock and Electron Acceleration in a Strongly Cavitated Laser Wakefield Accelerator
Helle, M. H.; Kaganovich, D.; Gordon, D. F.; Ting, A.
Conically emitted second harmonic radiation was observed when a relativistically intense, ultrashort laser pulse was focused into a jet of gas. This second harmonic electro-optic shock is the result of frequency mixing within the sheath of electrons surrounding a highly cavitated plasma region created by the ponderomotive force of the laser. Strong correlation between the second harmonic characteristics and electron acceleration has been observed.
Measurement of electro-optic shock and electron acceleration in a strongly cavitated laser wakefield accelerator.
Helle, M H; Kaganovich, D; Gordon, D F; Ting, A
Conically emitted second harmonic radiation was observed when a relativistically intense, ultrashort laser pulse was focused into a jet of gas. This second harmonic electro-optic shock is the result of frequency mixing within the sheath of electrons surrounding a highly cavitated plasma region created by the ponderomotive force of the laser. Strong correlation between the second harmonic characteristics and electron acceleration has been observed. PMID:20867524
Electro-optic and holographic measurement techniques for the atmospheric sciences. [considering spacecraft simulation applications
NASA Technical Reports Server (NTRS)
Moore, W. W., Jr.; Lemons, J. F.; Kurtz, R. L.; Liu, H.-K.
A comprehensive examination is made of recent advanced research directions in the applications of electro-optical and holographic instrumentations and methods to atmospheric sciences problems. In addition, an overview is given of the in-house research program for environmental and atmospheric measurements with emphasis on particulates systems. Special treatment is made of the instrument methods and applications work in the areas of laser scattering spectrometers and pulsed holography sizing systems. Selected engineering tests data on space simulation chamber programs are discussed.
Measured performance of an airborne Fourier-transform hyperspectral imager
NASA Astrophysics Data System (ADS)
Otten, Leonard John, III; Meigs, Andrew D.; Sellar, R. Glenn; Rafert, Bruce
A new hyperspectral imager has recently been developed by Kestrel Corporation for use in light aircraft platforms. The instrument provides 256 spectral channels with 87 cm-1 spectral bandwidth over the 450 nm to 1000 nm portion of the spectrum. Operated as a pushbroom imager, the FTVHSI has been shown to have a IFOV of 0.75 mrad, and a FOV of 0.23 rad. The sensor includes an internal spectral/radiometric calibration source, a self contained spectrally resolved downwelling sensor, and complete line of sight and GPS positioning information. The instrument is now operating from a Cessna TU-206 single engine aircraft.
Terahertz time-domain electro-optic measurements by femtosecond laser pulses with an edge-cut spectrum.
Ilyakov, I E; Kitaeva, G Kh; Shishkin, B V; Akhmedzhanov, R A
Balanced electro-optic detection techniques of terahertz wave radiation are proposed based on variations of the energy and ellipticity of laser pulses with an edge-cut spectrum. The techniques are compared with the standard electro-optic detection scheme utilizing laser pulses with Gaussian spectrum shape. Our calculations and measurements show that the studied schemes have a much better response to the terahertz wave radiation at high frequencies compared with the standard one. PMID:27367085
All-optical and electro-optical switches based on the interaction with disclination lines in chiral nematic liquid crystals
NASA Astrophysics Data System (ADS)
Laudyn, U. A.; Kwasny, M.; Sala, F. A.; Karpierz, M. A.
We outline the main features of spatial solitons called nematicons in chiral nematic liquid crystal confined in a wedge cell. We focus on electro-optic readdressing via the interaction with the disclination line to obtain highly steerable beam propagation. Nematicons can be effectively deviated by using the electro-optics response of the medium leading to voltage-control reconfiguration of light-induced guided-wave circuits and signal readdressing.
Frequency-agile hyper-Rayleigh scattering studies of electro-optic chromophores
NASA Astrophysics Data System (ADS)
Firestone, Kimberly A.; Lao, David B.; Casmier, Daniel M.; Clot, Olivier; Dalton, Larry R.; Reid, Philip J.
Hyper-Rayleigh scattering (HRS) is used to measure the first-hyperpolarizability (β) of electro-optic (EO) chromophores. One of the inherent concerns in any HRS measurement is the extent to which resonant enhancement contributes to the observed intensity thereby leading to inaccuracies when evaluating chromophore potential for application in electro-optical devices. One way to address this concern is to employ increasingly longer excitation wavelengths far from resonance. However, in charge-transfer-based non-linear optical chromophores, enhanced β generally correlates with a red-shift of the charge transfer absorption band so that even at the longest excitation wavelengths generally employed in HRS studies, resonant enhancement remains an issue. We have adopted an alternative approach in which the wavelength dispersion of the HRS intensity is determined by performing measurements at a variety of excitation wavelengths. This approach allows one to ascertain the role of resonance enhancement thereby allowing for more accurate correlation of improved β with molecular architecture. We report the results of our HRS studies for nine chromophores employing excitation wavelengths ranging from 780 to 1907 nm. Our HRS results demonstrate good agreement with the predictions of density functional theory. This synthesis of experimental and theoretical techniques has resulted in more effective designs for the next generations of electro-optical chromophores.
Terahertz time domain and far-infrared spectroscopies of side-chain electro-optic polymers
NASA Astrophysics Data System (ADS)
Yamada, Toshiki; Kaji, Takahiro; Aoki, Isao; Yamada, Chiyumi; Mizuno, Maya; Saito, Shingo; Tominari, Yukihiro; Tanaka, Shukichi; Otomo, Akira
We investigated the dielectric properties of side-chain electro-optic polymers in a broad THz frequency region (90 GHz to 7 THz). For this investigation, we used terahertz time domain spectroscopy and the absorption coefficient in a broader frequency region of up to 20 THz that was obtained by far-infrared spectroscopy. The polymers studied were a new methacrylate polymer with a high-hyperpolarizability chromophore as the sidechain, a side-chain copolymer Disperse Red 1 polymethylmethacrylate, and pure polymethylmethacrylate. The dielectric properties in the low THz frequency region (∼0.1 THz) provide us with important information about the intrinsic refractive index for ultrahigh-speed electro-optic modulation (∼100 GHz), as well as versatile information such as the absorption coefficient and dielectric loss. The THz and far-infrared spectroscopic data in the wide frequency region provide us with the fundamental data for applications of side-chain electro-optic polymers within THz generation and detection.
Electro-optic voltage sensor for sensing voltage in an E-field
Woods, Gregory K.; Renak, Todd W.
A miniature electro-optic voltage sensor system capable of accurate operation at high voltages. The system employs a transmitter, a sensor disposed adjacent to but out of direct electrical contact with a conductor on which the voltage is to be measured, a detector, and a signal processor. The transmitter produces a beam of electromagnetic radiation which is routed into the sensor where the beam undergoes the Pockels electro-optic effect. The electro-optic effect causes phase shifting in the beam, which is in turn converted to a pair of independent beams, from which the voltage of a system based on its E-field is determined when the two beams are normalized by the signal processor. The sensor converts the beam by splitting the beam in accordance with the axes of the beam's polarization state (an ellipse whose ellipticity varies between -1 and +1 in proportion to voltage) into at least two AM signals. These AM signals are fed into a signal processor and processed to determine the voltage between a ground conductor and the conductor on which voltage is being measured.
Electro-optic voltage sensor for sensing voltage in an E-field
Woods, G.K.; Renak, T.W.
A miniature electro-optic voltage sensor system capable of accurate operation at high voltages is disclosed. The system employs a transmitter, a sensor disposed adjacent to but out of direct electrical contact with a conductor on which the voltage is to be measured, a detector, and a signal processor. The transmitter produces a beam of electromagnetic radiation which is routed into the sensor where the beam undergoes the Pockels electro-optic effect. The electro-optic effect causes phase shifting in the beam, which is in turn converted to a pair of independent beams, from which the voltage of a system based on its E-field is determined when the two beams are normalized by the signal processor. The sensor converts the beam by splitting the beam in accordance with the axes of the beam`s polarization state (an ellipse whose ellipticity varies between -1 and +1 in proportion to voltage) into at least two AM signals. These AM signals are fed into a signal processor and processed to determine the voltage between a ground conductor and the conductor on which voltage is being measured. 18 figs.
Graphene electro-optic modulator with 30 GHz bandwidth
NASA Astrophysics Data System (ADS)
Phare, Christopher T.; Daniel Lee, Yoon-Ho; Cardenas, Jaime; Lipson, Michal
Graphene has generated exceptional interest as an optoelectronic material because its high carrier mobility and broadband absorption promise to make extremely fast and broadband electro-optic devices possible. Electro-optic graphene modulators previously reported, however, have been limited in bandwidth to a few gigahertz because of the large capacitance required to achieve reasonable voltage swings. Here, we demonstrate a graphene electro-optic modulator based on resonator loss modulation at critical coupling that shows drastically increased speed and efficiency. Our device operates with a 30 GHz bandwidth and with a state-of-the-art modulation efficiency of 15 dB per 10 V. We also show the first high-speed large-signal operation in a graphene modulator, paving the way for fast digital communications using this platform. The modulator uniquely uses silicon nitride waveguides, an otherwise completely passive material platform, with promising applications for ultra-low-loss broadband structures and nonlinear optics.
High-frequency electro-optic measurement of strained silicon racetrack resonators.
Borghi, M; Mancinelli, M; Merget, F; Witzens, J; Bernard, M; Ghulinyan, M; Pucker, G; Pavesi, L
The observation of the electro-optic effect in strained silicon waveguides has been considered a direct manifestation of an induced χ(2) nonlinearity in the material. In this work, we perform high-frequency measurements on strained silicon racetrack resonators. Strain is controlled by a mechanical deformation of the waveguide. It is shown that any optical modulation vanishes, independent of the applied strain, when the applied voltage varies much faster than the carrier effective lifetime and that the DC modulation is also largely independent of the applied strain. This demonstrates that plasma carrier dispersion is responsible for the observed electro-optic effect. After normalizing out free-carrier effects, our results set an upper limit of (8±3) pm/V to the induced high-speed effective χeff,zzz(2) tensor element at an applied stress of -0.5 GPa. This upper limit is about 1 order of magnitude lower than previously reported values for static electro-optic measurements. PMID:26565856
New electro-optic laser scanners for small-sat to ground laser communication links
NASA Astrophysics Data System (ADS)
Davis, Scott R.; Johnson, Seth T.; Rommel, Scott D.; Anderson, Michael H.; Chen, Jimmy; Chao, Tien-Hsin
In this paper we present new electro-optic beam steering technology and propose to combine it with optical telecommunication technology, thereby enabling low cost, compact, and rugged free space optical (FSO) communication modules for small-sat applications. Small satellite applications, particularly those characterized as "micro-sats" are often highly constrained by their ability to provide high bandwidth science data to the ground. This will often limit the relevance of even highly capable payloads due to the lack of data availability. FSO modules with unprecedented cost and size, weight, and power (SWaP) advantages will enable multi-access FSO networks to spread across previously inaccessible platforms. An example system would fit within a few cubic inch volume, require less than 1 watt of power and be able to provide ground station tracking (including orbital motion over wide angles and jitter correction) with a 50 to 100 Mbps downlink and no moving parts. This is possible, for the first time, because of emergent and unprecedented electro-optic (EO) laser scanners which will replace expensive, heavy, and power-consuming gimbal mechanisms. In this paper we will describe the design, construction, and performance of these new scanners. Specific examples to be discussed include an all electro-optic beamsteer with a 60 degree by 40 degree field of view. We will also present designs for a cube-sat to ground flight demonstration. This development would provide a significant enhancement in capabilities for future NASA and other Government and industry space projects.
Optical modulation techniques for analog signal processing and CMOS compatible electro-optic modulation
NASA Astrophysics Data System (ADS)
Gill, Douglas M.; Rasras, Mahmoud; Tu, Kun-Yii; Chen, Young-Kai; White, Alice E.; Patel, Sanjay S.; Carothers, Daniel; Pomerene, Andrew; Kamocsai, Robert; Beattie, James; Kopa, Anthony; Apsel, Alyssa; Beals, Mark; Mitchel, Jurgen; Liu, Jifeng; Kimerling, Lionel C.
Integrating electronic and photonic functions onto a single silicon-based chip using techniques compatible with mass-production CMOS electronics will enable new design paradigms for existing system architectures and open new opportunities for electro-optic applications with the potential to dramatically change the management, cost, footprint, weight, and power consumption of today's communication systems. While broadband analog system applications represent a smaller volume market than that for digital data transmission, there are significant deployments of analog electro-optic systems for commercial and military applications. Broadband linear modulation is a critical building block in optical analog signal processing and also could have significant applications in digital communication systems. Recently, broadband electro-optic modulators on a silicon platform have been demonstrated based on the plasma dispersion effect. The use of the plasma dispersion effect within a CMOS compatible waveguide creates new challenges and opportunities for analog signal processing since the index and propagation loss change within the waveguide during modulation. We will review the current status of silicon-based electrooptic modulators and also linearization techniques for optical modulation.
Externally-Modulated Electro-Optically Coupled Detector Architecture for Nuclear Physics Instrumentation
Xi, Wenze; McKisson, John E.; Weisenberger, Andrew G.; Zhang, Shukui; Zorn, Carl J.
A new laser-based externally-modulated electro-optically coupled detector (EOCD) architecture is being developed to enable high-density readout for radiation detectors with accurate analog radiation pulse shape and timing preservation. Unlike digital conversion before electro-optical modulation, the EOCD implements complete analog optical signal modulation and multiplexing in its detector front-end. The result is a compact, high performance detector readout that can be both radiation tolerant and immune to magnetic fields. In this work, the feasibility of EOCD was explored by constructing a two-wavelength laser-based externally-modulated EOCD, and testing analog pulse shape preservation and wavelength-division multiplexing (WDM) crosstalk. Comparisons were first made between the corresponding initial pulses and the electro-optically coupled analog pulses. This confirmed an excellent analog pulse preservation over $ sim {hbox {29}}% $ of the modulator's switching voltage range. Optical spectrum analysis revealed less than $-{hbox {14}}~hbox{dB}$ crosstalk with 1.2 nm WDM wavelength bandgap, and provided insight on experimental conditions that could lead to increased inter-wavelength crosstalk. Further discussions and previous research on the radiation tolerance and magnetic field immunity of the candidate materials were also given, and quantitative device testing is proposed in the future.
Electro-optic architecture (EOA) for sensors and actuators in aircraft propulsion systems
NASA Technical Reports Server (NTRS)
Glomb, W. L., Jr.
Results of a study to design an optimal architecture for electro-optical sensing and control in advanced aircraft and space systems are described. The propulsion full authority digital Electronic Engine Control (EEC) was the focus for the study. The recommended architecture is an on-engine EEC which contains electro-optic interface circuits for fiber-optic sensors on the engine. Size and weight are reduced by multiplexing arrays of functionally similar sensors on a pair of optical fibers to common electro-optical interfaces. The architecture contains common, multiplex interfaces to seven sensor groups: (1) self luminous sensors; (2) high temperatures; (3) low temperatures; (4) speeds and flows; (5) vibration; (6) pressures; and (7) mechanical positions. Nine distinct fiber-optic sensor types were found to provide these sensing functions: (1) continuous wave (CW) intensity modulators; (2) time division multiplexing (TDM) digital optic codeplates; (3) time division multiplexing (TDM) analog self-referenced sensors; (4) wavelength division multiplexing (WDM) digital optic code plates; (5) wavelength division multiplexing (WDM) analog self-referenced intensity modulators; (6) analog optical spectral shifters; (7) self-luminous bodies; (8) coherent optical interferometers; and (9) remote electrical sensors. The report includes the results of a trade study including engine sensor requirements, environment, the basic sensor types, and relevant evaluation criteria. These figures of merit for the candidate interface types were calculated from the data supplied by leading manufacturers of fiber-optic sensors.
Automatic bias control system of high speed electro-optic modulator in DPSK Systems
NASA Astrophysics Data System (ADS)
Xu, Miao; Tong, Shoufeng; Wang, Dashuai
In DPSK communication system, the traditional way for bias voltage is loading a fixed bias voltage on the electro-optic modulator. For the influence of the temperature changes, the half-wave voltage of the electro-optic modulator may change and the DC bias supply voltage will have a certain degree of random fluctuations at the meantime which will cause the DC bias point of the modulator drift and consequently the communication systems are affected. To enhance the stability of the DPSK optical communication system and control the bias of Mach-Zehnder electro-optic modulators automatically, a PID control method has been proposed in this paper. After the actual operation, a DPSK signal transmission with transfer rate of 5Gb/s is built. Using the complex spectrum analyzer, stable signal and the constellation can be received. The automatic control system basically meets the needs of the DPSK transmission system of high stability, high accuracy and capacity of resisting disturbance.
[Research on spatially modulated Fourier transform imaging spectrometer data processing method].
Huang, Min; Xiangli, Bin; Lü, Qun-Bo; Zhou, Jin-Song; Jing, Juan-Juan; Cui, Yan
Fourier transform imaging spectrometer is a new technic, and has been developed very rapidly in nearly ten years. The data catched by Fourier transform imaging spectrometer is indirect data, can not be used by user, and need to be processed by various approaches, including data pretreatment, apodization, phase correction, FFT, and spectral radicalization calibration. No paper so far has been found roundly to introduce this method. In the present paper, the author will give an effective method to process the interfering data to spectral data, and with this method we can obtain good result. PMID:20496726
A Super-Imaging Fourier Transform Spectrometer for the VLT
NASA Astrophysics Data System (ADS)
Maillard, Jean-Pierre; Bacon, Roland
A cryogenic, near-infrared (Hawaii2 domain) imaging FTS is proposed for a Nasmyth focus of an 8-m VLT, as a unique solution for providing integral field spectroscopy at high spectral resolution (R = 50,000 at 2 μm) over a large field, up to 3 x 3 arcmin FOV. Another mode is proposed behind AO with a smaller field but preserving high spectral resolution.
Asymmetric multiple-image encryption based on the cascaded fractional Fourier transform
NASA Astrophysics Data System (ADS)
Li, Yanbin; Zhang, Feng; Li, Yuanchao; Tao, Ran
A multiple-image cryptosystem is proposed based on the cascaded fractional Fourier transform. During an encryption procedure, each of the original images is directly separated into two phase masks. A portion of the masks is subsequently modulated into an interim mask, which is encrypted into the ciphertext image; the others are used as the encryption keys. Using phase truncation in the fractional Fourier domain, one can use an asymmetric cryptosystem to produce a real-valued noise-like ciphertext, while a legal user can reconstruct all of the original images using a different group of phase masks. The encryption key is an indivisible part of the corresponding original image and is still useful during decryption. The proposed system has high resistance to various potential attacks, including the chosen-plaintext attack. Numerical simulations also demonstrate the security and feasibility of the proposed scheme.
Electro-optical phenomena based on ionic liquids in an optofluidic waveguide.
He, Xiaodong; Shao, Qunfeng; Cao, Pengfei; Kong, Weijie; Sun, Jiqian; Zhang, Xiaoping; Deng, Youquan
An optofluidic waveguide with a simple two-terminal electrode geometry, when filled with an ionic liquid (IL), forms a lateral electric double-layer capacitor under a direct current (DC) electric field, which allows the realization of an extremely high carrier density in the vicinity of the electrode surface and terminals to modulate optical transmission at room temperature under low voltage operation (0 to 4 V). The unique electro-optical phenomenon of ILs was investigated at three wavelengths (663, 1330 and 1530 nm) using two waveguide geometries. Strong electro-optical modulations with different efficiencies were observed at the two near-infrared (NIR) wavelengths, while no detectable modulation was observed at 663 nm. The first waveguide geometry was used to investigate the position-dependent modulation along the waveguide; the strongest modulation was observed in the vicinity of the electrode terminal. The modulation phase is associated with the applied voltage polarity, which increases in the vicinity of the negative electrode and decreases at the positive electrode. The second waveguide geometry was used to improve the modulation efficiency. Meanwhile, the electro-optical modulations of seven ILs were compared at an applied voltage ranging from ±2 V to ±3.5 V. The results reveal that the modulation amplitude and response speed increase with increasing applied voltage, as well as the electrical conductivity of ILs. Despite the fact that the response speed isn't fast due to the high ionic density of ILs, the modulation amplitude can reach up to 6.0 dB when a higher voltage (U = ±3.5 V) is applied for the IL [Emim][BF4]. Finally, the physical explanation of the phenomenon was discussed. The effect of the change in IL structure on the electro-optical phenomena was investigated in another new experiment. The results reveal that the electro-optical phenomenon is probably caused mainly by the change in carrier concentration (ion redistribution near charged
Microwave and Electro-optical Transmission Experiments in the air-sea Boundary Layer
NASA Astrophysics Data System (ADS)
Anderson, K. D.
Microwave and electro-optical signal propagation over a wind-roughened sea is strongly dependent on signal interaction with the sea surface, the mean profiles of pressure (P), humidity (Q), temperature (T), wind (U) and their turbulent fluctuations (p, q, t, u). Yet, within the marine surface layer, these mechanisms are not sufficiently understood nor has satisfactory data been taken to validate propagation models, especially under conditions of high seas, high winds, and large surface gradients of Q and T. To address this deficiency, the Rough Evaporation Duct (RED) experiment was designed to provide first data for validation of meteorological, microwave, and electro-optical models in the marine surface layer for rough surface conditions including the effects of surface waves. The RED experiment was conducted offshore of the Hawaiian Island of Oahu in late summer, mid-August to mid-September, of 2001. R/P FLIP, moored about 10 km off of the NE coast of Oahu, hosted the primary meteorological sensor suites and served as a terminus for the propagation links. There were eleven scientists and engineers aboard R/P FLIP who installed instruments measuring mean and turbulent meteorological quantities, sea wave heights, directions, and kinematics, upward and downward radiance, near surface bubble generation, atmospheric particle size distributions, laser probing of the atmosphere, and sources for both microwave and electro-optic signals. In addition to R/P FLIP, two land sites were instrumented with microwave and electro-optic receivers and meteorological sensors, two buoys were deployed, a small boat was instrumented, and two aircraft flew various tracks to sense both sea and atmospheric conditions. In all, more than 25 people from four countries, six universities, and four government agencies were directly involved with the RED experiment. While the overall outcome of the RED experiment is positive, we had a number of major and minor problems with the outfitting
Remote ballistic emplacement of an electro-optical and acoustic target detection and localization system
NASA Astrophysics Data System (ADS)
West, Aaron; Mellini, Mark
Near real time situational awareness in uncontrolled non line of sight (NLOS) and beyond line of sight (BLOS) environments is critical in the asymmetric battlefield of future conflicts. The ability to detect and accurately locate hostile forces in difficult terrain or urban environments can dramatically increase the survivability and effectiveness of dismounted soldiers, especially when they are limited to the resources available only to the small unit. The Sensor Mortar Network (SMortarNet) is a 60mm Intelligence, Surveillance, and Reconnaissance (ISR) mortar designed to give the Squad near real time situational awareness in uncontrolled NLOS environments. SMortarNet is designed to track targets both acoustically and electro optically and can fuse tracks between, the acoustic, EO, and magnetic modalities on board. The system is linked to other mortar nodes and the user via a masterless frequency hopping spread spectrum ad-hoc mesh radio network. This paper will discuss SMortarNet in the context of a squad level dismounted soldier, its technical capabilities, and its benefit to the small unit Warfighter. The challenges with ballistic remote emplacement of sensitive components and the on board signal processing capabilities of the system will also be covered. The paper will also address how the sensor network can be integrated with existing soldier infrastructure, such as the NettWarrior platform, for rapid transition to soldier systems. Networks of low power sensors can have many forms, but the more practical networks for warfighters are ad hoc radio-based systems that can be rapidly deployed and can leverage a range of assets available at a given time. The low power long life networks typically have limited bandwidth and may have unreliable communication depending on the network health, which makes autonomous sensors a critical component of the network. SMortarNet reduces data to key information features at the sensor itself. The smart sensing approach enables
Spectral multiplexing and coherent-state decomposition in Fourier ptychographic imaging
Dong, Siyuan; Shiradkar, Radhika; Nanda, Pariksheet; Zheng, Guoan
Information multiplexing is important for biomedical imaging and chemical sensing. In this paper, we report a microscopy imaging technique, termed state-multiplexed Fourier ptychography (FP), for information multiplexing and coherent-state decomposition. Similar to a typical Fourier ptychographic setting, we use an array of light sources to illuminate the sample from different incident angles and acquire corresponding low-resolution images using a monochromatic camera. In the reported technique, however, multiple light sources are lit up simultaneously for information multiplexing, and the acquired images thus represent incoherent summations of the sample transmission profiles corresponding to different coherent states. We show that, by using the state-multiplexed FP recovery routine, we can decompose the incoherent mixture of the FP acquisitions to recover a high-resolution sample image. We also show that, color-multiplexed imaging can be performed by simultaneously turning on R/G/B LEDs for data acquisition. The reported technique may provide a solution for handling the partially coherent effect of light sources used in Fourier ptychographic imaging platforms. It can also be used to replace spectral filter, gratings or other optical components for spectral multiplexing and demultiplexing. With the availability of cost-effective broadband LEDs, the reported technique may open up exciting opportunities for computational multispectral imaging. PMID:24940538
Full-Stokes Fourier-transform imaging spectropolarimeter using a time-division polarization modulator.
Meng, Xin; Li, Jianxin; Song, Huaqing; Zhu, Rihong
A Fourier-transform imaging spectropolarimeter is presented and demonstrated. It is composed of a time-division polarization modulator and a high radiation throughput Fourier-transform spectrometer. Four polarization states of the input light are generated by rotating the retarder. Then, the polarized light enters the Fourier-transform spectrometer to create four sets of interferometric images, where we can recover four polarization spectra and calculate the full-Stokes vector in various wavenumber frequency. The method has good performance to resist instrument noise and has the advantage of high spatial resolution. The laboratory setup is described and the noise source is analyzed. Two proven experiments have been carried out in visible light. PMID:25321096
The Bulk Density of Meteoroids from Electro-Optical Measurements
NASA Astrophysics Data System (ADS)
Kikwaya-Eluo, J.-B.; Brown, P.; Hawkes, R. L.
The mean bulk density of small meteoroids remains a poorly measured quantity. Based on photographic observations of large (gram-sized) meteoroids and the theory of quasi-continuous fragmentation Lebedinets (1987) and Babadzhanov (1994) estimated the average bulk density of meteoroids to be near 3300kg m-3, with values for individual meteoroids ranging from 100 and 8000 kg m-3. These high values are close to the density of solid-iron and stony meteorites and have been shown to contradict some of the assumptions of the quasi-continuous theory (Bellot Rubio et al., 2002). In contrast, application of the competing single body theory (i.e. the heating of the meteoroid occurs without intensive ablation) on 370 meteors with a magnitude range between +2.5 and -5 mag (McCrosky and Posen, 1961) by Bellot et al. (2002) found low values for the density of meteoroids in a similar mass range. For sporadic meteors, Bellot et al. (2002) found an average density of 800 kg m-3, while the density for individual meteoroids ranged from 100 to 4500 kg m-3. Here we report our attempt to measure the bulk density of smaller ( mg) meteoroids using the single body model applied to low-light-level tv (LLLTV) observations. Our data are gathered from two stations (separation 50 km). One station uses a digital, gated image intensifier coupled to a megapixel CCD detector, while the other station uses an image intensifier coupled to a video-rate CCD. The gated sensor permits high temporal snapshots (0.5 ms) of meteors which can then be combined with the LLLTV systems at the second site to define both the trajectory and velocity of the meteoroid to high precision. It is our goal to detect significant deceleration in a sample of both shower and sporadic meteors. Absence of significant wake in the gated images is used as a criterion to select those meteors for which fragmentation is not important and thus application of the single body model is most appropriate.
Image deconvolution of extended objects - A comparison of the inverse Fourier and the Lucy techniques
NASA Astrophysics Data System (ADS)
Cunningham, C. C.; Anthony, D.
Two methods of deconvolution, the inverse Fourier method and the Lucy iterative technique, are compared with respect to their applicability to restoration of Hubble Space Telescope images of Saturn. The two techniques are found to provide nearly identical results in the case of cloud morphologies and comparable results for fluxes from Saturn's bright disk.
Gallery of Datacubes Obtained with the Livermore Imaging Fourier Transform Spectrometer
Wurtz, R; Wishnow, E H; Blais-Ouellette, S; Cook, K H; Holden, B P; Carr, D J; Stubbs, C W
We have acquired spatial-spectral datacubes of astronomical objects using the Livermore visible-band imaging Fourier transform spectrometer at Apache Point Observatory. Each raw datacube contains hundreds of thousands of spectral interferograms. We present in-progress demonstrations of these observations.
Gaseous effluent monitoring and identification using an imaging Fourier transform spectrometer
Carter, M.R.; Bennett, C.L.; Fields, D.J.; Hernandez, J.
We are developing an imaging Fourier transform spectrometer for chemical effluent monitoring. The system consists of a 2-D infrared imaging array in the focal plane of a Michelson interferometer. Individual images are coordinated with the positioning of a moving mirror in the Michelson interferometer. A three dimensional data cube with two spatial dimensions and one interferogram dimension is then Fourier transformed to produce a hyperspectral data cube with one spectral dimension and two spatial dimensions. The spectral range of the instrument is determined by the choice of optical components and the spectral range of the focal plane array. Measurements in the near UV, visible, near IR, and mid-IR ranges are possible with the existing instrument. Gaseous effluent monitoring and identification measurements will be primarily in the ``fingerprint`` region of the spectrum, ({lambda} = 8 to 12 {mu}m). Initial measurements of effluent using this imaging interferometer in the mid-IR will be presented.
Incubator embedded cell culture imaging system (EmSight) based on Fourier ptychographic microscopy.
Kim, Jinho; Henley, Beverley M; Kim, Charlene H; Lester, Henry A; Yang, Changhuei
Multi-day tracking of cells in culture systems can provide valuable information in bioscience experiments. We report the development of a cell culture imaging system, named EmSight, which incorporates multiple compact Fourier ptychographic microscopes with a standard multiwell imaging plate. The system is housed in an incubator and presently incorporates six microscopes. By using the same low magnification objective lenses as the objective and the tube lens, the EmSight is configured as a 1:1 imaging system that, providing large field-of-view (FOV) imaging onto a low-cost CMOS imaging sensor. The EmSight improves the image resolution by capturing a series of images of the sample at varying illumination angles; the instrument reconstructs a higher-resolution image by using the iterative Fourier ptychographic algorithm. In addition to providing high-resolution brightfield and phase imaging, the EmSight is also capable of fluorescence imaging at the native resolution of the objectives. We characterized the system using a phase Siemens star target, and show four-fold improved coherent resolution (synthetic NA of 0.42) and a depth of field of 0.2 mm. To conduct live, long-term dopaminergic neuron imaging, we cultured ventral midbrain from mice driving eGFP from the tyrosine hydroxylase promoter. The EmSight system tracks movements of dopaminergic neurons over a 21 day period. PMID:27570701
Incubator embedded cell culture imaging system (EmSight) based on Fourier ptychographic microscopy
Kim, Jinho; Henley, Beverley M.; Kim, Charlene H.; Lester, Henry A.; Yang, Changhuei
Multi-day tracking of cells in culture systems can provide valuable information in bioscience experiments. We report the development of a cell culture imaging system, named EmSight, which incorporates multiple compact Fourier ptychographic microscopes with a standard multiwell imaging plate. The system is housed in an incubator and presently incorporates six microscopes. By using the same low magnification objective lenses as the objective and the tube lens, the EmSight is configured as a 1:1 imaging system that, providing large field-of-view (FOV) imaging onto a low-cost CMOS imaging sensor. The EmSight improves the image resolution by capturing a series of images of the sample at varying illumination angles; the instrument reconstructs a higher-resolution image by using the iterative Fourier ptychographic algorithm. In addition to providing high-resolution brightfield and phase imaging, the EmSight is also capable of fluorescence imaging at the native resolution of the objectives. We characterized the system using a phase Siemens star target, and show four-fold improved coherent resolution (synthetic NA of 0.42) and a depth of field of 0.2 mm. To conduct live, long-term dopaminergic neuron imaging, we cultured ventral midbrain from mice driving eGFP from the tyrosine hydroxylase promoter. The EmSight system tracks movements of dopaminergic neurons over a 21 day period. PMID:27570701
Image Stability Requirements For a Geostationary Imaging Fourier Transform Spectrometer (GIFTS)
NASA Technical Reports Server (NTRS)
Bingham, G. E.; Cantwell, G.; Robinson, R. C.; Revercomb, H. E.; Smith, W. L.
A Geostationary Imaging Fourier Transform Spectrometer (GIFTS) has been selected for the NASA New Millennium Program (NMP) Earth Observing-3 (EO-3) mission. Our paper will discuss one of the key GIFTS measurement requirements, Field of View (FOV) stability, and its impact on required system performance. The GIFTS NMP mission is designed to demonstrate new and emerging sensor and data processing technologies with the goal of making revolutionary improvements in meteorological observational capability and forecasting accuracy. The GIFTS payload is a versatile imaging FTS with programmable spectral resolution and spatial scene selection that allows radiometric accuracy and atmospheric sounding precision to be traded in near real time for area coverage. The GIFTS sensor combines high sensitivity with a massively parallel spatial data collection scheme to allow high spatial resolution measurement of the Earth's atmosphere and rapid broad area coverage. An objective of the GIFTS mission is to demonstrate the advantages of high spatial resolution (4 km ground sample distance - gsd) on temperature and water vapor retrieval by allowing sampling in broken cloud regions. This small gsd, combined with the relatively long scan time required (approximately 10 s) to collect high resolution spectra from geostationary (GEO) orbit, may require extremely good pointing control. This paper discusses the analysis of this requirement.
Precise spectrum reconstruction of the Fourier transforms imaging spectrometer based on polarization beam splitters.
Ren, Wenyi; Zhang, Chunmin; Jia, Chenling; Mu, Tingkui; Li, Qiwei; Zhang, Lin
A method was proposed to precisely reconstruct the spectrum from the interferogram taken by the Fourier transform imaging spectrometer (FTIS) based on the polarization beam splitters. Taken the FTISs based on the Savart polariscope and Wollaston prism as examples, the distorted spectrums were corrected via the proposed method effectively. The feasibility of the method was verified via simulation. The distorted spectrum, recovered from the interferogram taken by the polarization imaging spectrometer developed by us, was corrected. PMID:23595463
Two-dimensional Kerr-Fourier imaging of translucent phantoms in thick turbid media
NASA Astrophysics Data System (ADS)
Liang, X.; Wang, L.; Ho, P. P.; Alfano, R. R.
Translucent scattering phantoms hidden inside a 5.5-cm-thick Intralipid solution were imaged as a function of phantom scattering coefficients by the use of a picosecond time-and space-gated Kerr-Fourier imaging system. A 2-mm-thick translucent phantom with a 0.1% concentration (scattering coefficient) difference from the 55-mm-thick surrounding scattering host can be distinguished at a signal level of approximately 10-10 of the incidence illumination intensity.
Shuttle pointing of electro-optical experiments; Proceedings of the Seminar, Los Angeles, Calif., February 10-13, 1981
NASA Astrophysics Data System (ADS)
Jerkovsky, W.
A Spacelab/sortie program overview is presented and related programs and techniques are discussed. Pointing systems are considered along with optical sensors for pointing systems, Spacelab experiments, sortie experiments, and future experiments and programs. Attention is given to European pointed experiments on the first Spacelab payload, Spacelab 2 pointed experiments, crew optimized Shuttle/experiment pointing, interactive data analysis for astronomy Shuttle experiments at Goddard Space Flight Center, an overview of infrared measurement programs, a 102 cm balloon-borne telescope for far-infrared astronomical observations, analysis techniques applied to balloon-borne mosaic interferometer and radiometer measurements, reduction and analysis of electrographic imagery and spectra, Skylab's Apollo telescope mount, experiment pointing with magnetic suspension, Gimbalfex fine pointing system, design considerations for imaging charge-coupled device star sensors, a solid-state aspect sensor, attitude transfer by electro-optical instrumentation for Shuttle experiments, an atmospheric emissions photometric imaging experiment for Spacelab 1, and orbital operations with the Shuttle infrared telescope facility.
Target recognition: fusing long-wave infrared and electro-optical imagery for detection of humans in a scene
NASA Astrophysics Data System (ADS)
Woodyard, R. L.; Skipper, J. A.; Repperger, D. W.
We aim to identify humans in multimodal imagery by predicting the human long-wave infrared (LWIR) signature in a variety of scenarios. By adapting Tanabe's thermocomfort model, we simulate human body heat flow both between tissue layers (core, muscle, fat and skin) and between body segments (head, chest, upper arm, etc.). To assess the validity of our implementation, we simulated the conditions described in actual human subject studies, and compared our results to values reported in the literature. Inputs to the model include age, height, weight, clothing, physical activity and ambient conditions, including temperature, humidity and wind velocity. Iteration of heat transport equations and a thermoregulatory component yields temporal data of segment surface temperature. Our model was found to be in close agreement with experimentally collected data, with a maximum deviation from literature values of approximately 0.80%. By comparing the predicted human thermal signature to deblurred LWIR images and then fusing this information at the feature level with high-resolution electro-optical image data, we can facilitate identity detection of objects in a scene acquired under different conditions. Ultimately, our goal is to differentiate humans from their surroundings and label non-human objects as thermal clutter.
Optical coherence tomography for imaging of subpleural alveolar structure using a Fourier domain mode locked laser
NASA Astrophysics Data System (ADS)
Kirsten, Lars; Walther, Julia; Cimalla, Peter; Gaertner, Maria; Meissner, Sven; Koch, Edmund
Optical coherence tomography (OCT) is a noninvasive imaging modality generating cross sectional and volumetric images of translucent samples. In Fourier domain OCT (FD OCT), the depth profile is calculated by a fast Fourier transformation of the interference spectrum, providing speed and SNR advantage and thus making FD OCT well suitable in biomedical applications. The interference spectrum can be acquired spectrally resolved in spectral domain OCT or time-resolved in optical frequency domain imaging (OFDI). Since OCT images still suffer from motion artifacts, especially under in vivo conditions, increased depth scan rates are required. Therefor, the principle of Fourier domain mode locking has been presented by R. Huber et al. circumventing the speed limitations of conventional FD OCT systems. In FDML lasers, a long single mode fiber is inserted in the ring resonator of the laser resulting in an optical round trip time of a few microseconds. Sweeping the wavelength synchronously by a tunable Fabry-Perot filter can provide wavelength sweeps with repetition rates up to a few MHz used for OFDI. Imaging of subpleural lung tissue for investigation of lung dynamics and its elastic properties is a further biomedical application demanding high-speed OCT imaging techniques. For the first time, the visualization of subpleural alveolar structures of a rabbit lung is presented by the use of an FDML-based OCT system enabling repetition rates of 49.5 kHz and 122.6 kHz, respectively.
Hydrogen bonding intermolecular effect on electro-optical response of doped 6PCH nematic liquid crystal with some azo dyes
NASA Astrophysics Data System (ADS)
Kiani, S.; Zakerhamidi, M. S.; Tajalli, H.
Previous studies on the electro-optical responses of dye-doped liquid crystal have shown that dopant material have a considerable effect on their electro-optical responses. Despite the studies carried out on electro-optical properties of dye-doped liquid crystal, no attention has been paid to study of the interaction and structural effects in this procedure. In this paper, linear dyes and with similar structure were selected as dopants. The only difference in used dyes is the functional groups in their tails. So, doping of these dyes into liquid crystals determines the influence of interaction type on electro-optical behaviours of the doped systems. Therefore, in this work, two aminoazobenzene ("A-dye": hydrogen bond donor) and dimethyl-aminoazobenzene ("B-dye") dyes with different compositional percentages in liquid crystal host were used. Electro-optical Kerr behaviour, the pre-transition temperature and third order nonlinear susceptibility were investigated. The obtained results effectively revealed that type of interactions between the dye and liquid crystal is determinative of behavioral difference of doped system, compared to pure liquid crystal. Also, pre-transitional behaviour and thereupon Kerr electro-optical responses were affected by formed interactions into doped systems. In other words, it will be shown that addition of any dopants in liquid crystal, regardless of the nature of interactions, cannot cause appropriate electro-optical responses. In fact, type of dye, nature of interactions between dopant and liquid crystalline host as well as concentration of dye are the key factors in selecting the appropriate liquid crystal and dopant dye.
An image hiding method based on cascaded iterative Fourier transform and public-key encryption algorithm
NASA Astrophysics Data System (ADS)
Zhang, B.; Sang, Jun; Alam, Mohammad S.
An image hiding method based on cascaded iterative Fourier transform and public-key encryption algorithm was proposed. Firstly, the original secret image was encrypted into two phase-only masks M1 and M2 via cascaded iterative Fourier transform (CIFT) algorithm. Then, the public-key encryption algorithm RSA was adopted to encrypt M2 into M2' . Finally, a host image was enlarged by extending one pixel into 2×2 pixels and each element in M1 and M2' was multiplied with a superimposition coefficient and added to or subtracted from two different elements in the 2×2 pixels of the enlarged host image. To recover the secret image from the stego-image, the two masks were extracted from the stego-image without the original host image. By applying public-key encryption algorithm, the key distribution was facilitated, and also compared with the image hiding method based on optical interference, the proposed method may reach higher robustness by employing the characteristics of the CIFT algorithm. Computer simulations show that this method has good robustness against image processing.
Novel Algorithm for Polar and Spherical Fourier Analysis on Two and Three Dimensional Images
NASA Astrophysics Data System (ADS)
Yang, Zhuo; Kamata, Sei-Ichiro
Polar and Spherical Fourier analysis can be used to extract rotation invariant features for image retrieval and pattern recognition tasks. They are demonstrated to show superiorities comparing with other methods on describing rotation invariant features of two and three dimensional images. Based on mathematical properties of trigonometric functions and associated Legendre polynomials, fast algorithms are proposed for multimedia applications like real time systems and large multimedia databases in order to increase the computation speed. The symmetric points are computed simultaneously. Inspired by relative prime number theory, systematic analysis are given in this paper. Novel algorithm is deduced that provide even faster speed. Proposed method are 9-15% faster than previous work. The experimental results on two and three dimensional images are given to illustrate the effectiveness of the proposed method. Multimedia signal processing applications that need real time polar and spherical Fourier analysis can be benefit from this work.
A compact Fourier transform imaging spectrometer employing a variable gap Fabry-Perot interferometer
NASA Astrophysics Data System (ADS)
Lucey, Paul G.; Akagi, Jason; Bingham, Adam L.; Hinrichs, John L.; Knobbe, Edward T.
Fourier transform spectroscopy is a widely employed method for obtaining visible and infrared spectral imagery, with applications ranging from the desktop to remote sensing. Most fielded Fourier transform spectrometers (FTS) employ the Michelson interferometer and measure the spectrum encoded in a time-varying signal imposed by the source spectrum interaction with the interferometer. A second, less widely used form of FTS is the spatial FTS, where the spectrum is encoded in a pattern sampled by a detector array. Recently we described using a Fabry-Perot interferometer, with a deliberately wedged gap geometry and engineered surface reflectivities, to produce an imaging spatial FTS. The Fabry-Perot interferometer can be much lighter and more compact than a conventional interferometer configuration, thereby making them suitable for portable and handheld applications. This approach is suitable for use over many spectral regimes of interest, including visible and infrared regions. Primary efforts to date have focused on development and demonstration of long wave infrared (LWIR) spectral imagers. The LWIR version of the miniaturized Fabry-Perot has been shown to be effective for various applications including spectral imaging-based chemical detection. The compact LWIR spectral imager employs uncooled optics and a microbolometer camera; a handheld version is envisioned for future development. Recent advancements associated with the spatial Fourier Transform imaging spectrometer system are described.
Characterization of devices, circuits, and high-temperature superconductor transmission lines by electro-optic testing
NASA Technical Reports Server (NTRS)
Whitaker, John F.
The development of a capability for testing transmission lines, devices, and circuits using the optically-based technique of electro-optics sampling was the goal of this project. Electro-optic network analysis of a high-speed device was demonstrated. The project involved research on all of the facets necessary in order to realize this result, including the discovery of the optimum electronic pulse source, development of an adequate test fixture, improvement of the electro-optic probe tip, and identification of a device which responded at high frequency but did not oscillate in the test fixture. In addition, during the process of investigating patterned high-critical-temperature superconductors, several non-contacting techniques for the determination of the transport properties of high T(sub c) films were developed and implemented. These are a transient, optical pump-probe, time-resolved reflectivity experiment, an impulsive-stimulated Raman scattering experiment, and a terahertz-beam coherent-spectroscopy experiment. The latter technique has enabled us to measure both the complex refractive index of an MgO substrate used for high-T(sub c) films and the complex conductivity of a YBa2Cu3O(7-x) sample. This information was acquired across an extremely wide frequency range: from the microwave to the submillimeter-wave regime. The experiments on the YBCO were conducted without patterning of, or contact to, the thin film. Thus, the need for the more difficult transmission-line experiments was eliminated. Progress in all of these areas was made and is documented in a number of papers. These papers may be found in the section listing the abstracts of the publications that were issued during the course of the research.
Nanoengineering of Soft Matter Interactions in Organic Electro-Optic Materials
NASA Astrophysics Data System (ADS)
Benight, Stephanie J.
Identification of electronic intermolecular electrostatic interactions that can significantly enhance poling-induced order is important to the advancement of the field of organic electro-optics and utilization of organic materials in photonics applications. Here we demonstrate an example of such improvement achieved through exploitation of the interaction of coumarin pendant groups in chromophore-containing macromolecules. The synthetic attachment of these pendant groups to electro-optic (EO) chromophores promotes intermolecular cooperativity as demonstrated by a 2-3 fold increase in macroscopic EO activity (acentric order). Acentric order enhancement is explained in terms of lattice-symmetry effects, where constraint of orientational degrees of freedom alters the relationship between centrosymmetric and acentric order. We demonstrate both experimentally and theoretically that lattice dimensionality can be defined using the relationship between centrosymmetric order and acentric order. Experimentally: Acentric order is determined by attenuated total reflection (ATR) measurement of electro-optic activity coupled with hyper-Rayleigh scattering (HRS) measurement of molecular first hyperpolarizability while centrosymmetric order is determined by the variable angle polarization referenced absorption spectroscopy (VAPRAS) method. These measurements of chromophore order and lattice dimensionality are correlated with measurements of viscoelastic properties by Shear Modulation Force Microscopy (SM-FM), Intrinsic Friction Analysis (IFA), and Dielectric Relaxation Spectroscopy (DRS), leading to a self-consistent picture of the effect of specific spatially-anisotropic intermolecular interactions upon the physical properties of nanoengineered soft matter EO materials. Theoretically: Order is determined from statistical mechanical models that predict the properties of soft condensed matter. Exploration of this reduced dimensionality effect is explored through attachment of
Fourier-based linear systems description of free-breathing pulmonary magnetic resonance imaging
NASA Astrophysics Data System (ADS)
Capaldi, D. P. I.; Svenningsen, S.; Cunningham, I. A.; Parraga, G.
Fourier-decomposition of free-breathing pulmonary magnetic resonance imaging (FDMRI) was recently piloted as a way to provide rapid quantitative pulmonary maps of ventilation and perfusion without the use of exogenous contrast agents. This method exploits fast pulmonary MRI acquisition of free-breathing proton (1H) pulmonary images and non-rigid registration to compensate for changes in position and shape of the thorax associated with breathing. In this way, ventilation imaging using conventional MRI systems can be undertaken but there has been no systematic evaluation of fundamental image quality measurements based on linear systems theory. We investigated the performance of free-breathing pulmonary ventilation imaging using a Fourier-based linear system description of each operation required to generate FDMRI ventilation maps. Twelve subjects with chronic obstructive pulmonary disease (COPD) or bronchiectasis underwent pulmonary function tests and MRI. Non-rigid registration was used to co-register the temporal series of pulmonary images. Pulmonary voxel intensities were aligned along a time axis and discrete Fourier transforms were performed on the periodic signal intensity pattern to generate frequency spectra. We determined the signal-to-noise ratio (SNR) of the FDMRI ventilation maps using a conventional approach (SNRC) and using the Fourier-based description (SNRF). Mean SNR was 4.7 ± 1.3 for subjects with bronchiectasis and 3.4 ± 1.8, for COPD subjects (p>.05). SNRF was significantly different than SNRC (p<.01). SNRF was approximately 50% of SNRC suggesting that the linear system model well-estimates the current approach.
Digital watermarking algorithm research of color images based on quaternion Fourier transform
NASA Astrophysics Data System (ADS)
An, Mali; Wang, Weijiang; Zhao, Zhen
A watermarking algorithm of color images based on the quaternion Fourier Transform (QFFT) and improved quantization index algorithm (QIM) is proposed in this paper. The original image is transformed by QFFT, the watermark image is processed by compression and quantization coding, and then the processed watermark image is embedded into the components of the transformed original image. It achieves embedding and blind extraction of the watermark image. The experimental results show that the watermarking algorithm based on the improved QIM algorithm with distortion compensation achieves a good tradeoff between invisibility and robustness, and better robustness for the attacks of Gaussian noises, salt and pepper noises, JPEG compression, cropping, filtering and image enhancement than the traditional QIM algorithm.
Double image encryption based on random phase encoding in the fractional Fourier domain.
Tao, Ran; Xin, Yi; Wang, Yue
A novel image encryption method is proposed by utilizing random phase encoding in the fractional Fourier domain to encrypt two images into one encrypted image with stationary white distribution. By applying the correct keys which consist of the fractional orders, the random phase masks and the pixel scrambling operator, the two primary images can be recovered without cross-talk. The decryption process is robust against the loss of data. The phase-based image with a larger key space is more sensitive to keys and disturbances than the amplitude-based image. The pixel scrambling operation improves the quality of the decrypted image when noise perturbation occurs. The novel approach is verified by simulations. PMID:19550895
Pockel's electro-optic coefficients of lithium tetraborate Li2B4O7
NASA Astrophysics Data System (ADS)
Méndez, A.; García-Cabañes, A.; Diéguez, E.; Cabrera, J. M.
Pockel's electro-optic coefficients r31 and r33 of Li2B4O7 have been measured with an improved interferometric (Mach-Zehnder) method. The effective rc coefficient has also been measured by a polarimetric setup which, within the experimental error, has given the same value as that of the interferometric method. Attempts to measure the r42 coefficient with either the interferometric or the polarimetric method have given a value below the detection limit of our setups. All coefficients are given in terms of the published values of the piezoelectric coefficient d13.
High-Sensitivity Optical Pulse Characterization Using Sagnac Electro-Optic Spectral Shearing Interferometry
Dorrer, C.; Bromage, J.
An electro-optic spectral shearing interferometer for high-sensitivity optical pulse characterization is described. Two replicas of the test pulse counterpropagate in a Sagnac interferometer with orthogonal polarization states, resulting in two relatively sheared copolarized replicas after temporal phase modulation. The polarization interferometer is intrinsically stable, and its birefringence sets the delay between interfering replicas to reduce the spectrometer resolution requirement. Experimental implementations demonstrate real-time pulse characterization at average powers as low as 1 nWwith spectral shears as high as 280 GHz.
Electro-optical sun compass with a very high degree of accuracy.
Bollanti, Sarah; De Meis, Domenico; Di Lazzaro, Paolo; Flora, Francesco; Gallerano, Gian Piero; Mezi, Luca; Murra, Daniele; Torre, Amalia; Vicca, Davide
We present a novel electro-optical solar compass that is able to determine the true North direction with an accuracy better than 1/100 of degree, superior to that of any other magnetic or electronic compass that does not resort to differential GPS. The compass has an electronic sensor to determine the line of sight of the Sun and a simple but effective algorithm to calculate the position of the Sun. The excellent results obtained during the experimental tests demonstrate the advantages of this compass, which is also compact and not expensive. PMID:26258372
Characterization of lithium niobate electro-optic modulators at cryogenic temperatures
NASA Astrophysics Data System (ADS)
Morse, Jeffrey D.; McCammon, Kent G.; McConaghy, Charles F.; Masquelier, Don A.; Garrett, Henry E.; Lowry, Mark E.
This paper reports on the operation of lithium niobate electro-optic waveguide modulators at temperatures down to 15 degree(s)K. Commercial and laboratory fiber pigtailed devices have successfully been cooled without any increases in insertion loss from temperature induced stresses in device packaging. Three x-cut devices exhibited a linear increase in Vpi voltage of 8% +/- 1% when cooled from room temperature to approximately 20 degree(s)K. The broadband frequency response improved at lower temperatures. A velocity-matched experimental modulator has shown increased bandwidth when cooled to liquid nitrogen temperature.
New Remote Gas Sensor Using Rapid Electro-Optical Path Switching
NASA Technical Reports Server (NTRS)
Sachse, G. W.; Lebel, P. J.; Wallio, H. A.; Vay, S. A.; Wang, L. G.
Innovative gas filter correlation radiometer (GFCR) features nonmechanical switching of internal optical paths. Incoming radiation switched electro-optically, by means of polarization, between two optical paths, one of which contains correlation gas cell while other does not. Advantages include switching speed, 2 to 3 orders of magnitude faster than mechanical techniques, and high reliability. Applications include regional studies of atmospheric chemistry from either manned or unmanned aircraft as well as satellite studies of global distributions, sources and sink mechanisms for key species involved in chemistry of troposphere. Commercial applications: ability to survey many miles of natural gas pipelines rapidly from aircraft, pinpointing gas leaks by measuring methane at 2.3 micrometers.
Characterization of lithium niobate electro-optic modulators at cryogenic temperatures
Morse, J.; McCammon, K.; McConaghy, C.; Masquelier, D.; Garrett, H.; Lowry, M.
This paper reports on the operation of lithium niobate electro-optic waveguide modulators at temperatures down to 15{degrees}K. Commercial and laboratory fiber pigtailed devices have successfully been cooled without any increases in insertion loss from temperature induced stresses in device packaging. Three x-cut devices exhibited a linear increase in V{pi} voltage of 8%{plus_minus}1% when cooled from room temperature to {approximately} 20{degree}K. The broadband frequency response improved at lower temperature. A velocity-matched experimental modular has shown increased bandwidth when cooled to liquid nitrogen temperature.
Polymeric waveguide electro-optic beam-steering device with DNA biopolymer conductive cladding layers
NASA Astrophysics Data System (ADS)
Aga, Roberto S.; Ouchen, Fahima; Lesko, Alyssa; Telek, Brian A.; Fehrman Cory, Emily M.; Bartsch, Carrie M.; Lombardi, Jack; Grote, James; Heckman, Emily M.
A polymer electro-optic (EO) waveguide beam-steering device with deoxyribonucleic acid (DNA) biopolymer conductive cladding layers and a core layer of the commercially available EO polymer SEO100 is demonstrated with 100% relative poling efficiency. This demonstration device exhibits a deflection efficiency of 99 mrad/kV with a corresponding in-device EO coefficient r33 of 124 pm/V at 1550 nm. When the DNA biopolymer bottom cladding layer is replaced by the commonly used cladding polymer UV15, the deflection efficiency and in-device r33 drop to 34 mrad/kV and 43 pm/V, respectively.
Self-Action of Light Fields in Waveguide Photon Structures Based on Electro-Optic Crystals
NASA Astrophysics Data System (ADS)
Shandarov, V. M.
Special features of spatial self-action of light fields in nonlinear optical photonic waveguide structures formed in strontium barium niobate and lithium niobate electro-optic crystals are discussed. The main methods of forming such structures including photorefractive waveguide elements and systems are briefly considered. The formation of spatial optical solitons in planar waveguides based on lithium niobate and strontium barium niobate crystals as well as in one-dimensional photonic lattices in lithium niobate is demonstrated experimentally for light beams of microwatt power. In regimes of spatial optical solitons, channel optical waveguides are formed not only in the planar waveguides, but also in the volume of photorefractive lithium niobate.
Optical switch using electro-optic crystal with phase matching films
NASA Astrophysics Data System (ADS)
Shirasaki, M.; Takagi, N.; Obokata, T.
An electro-optical switch for the 1.3 micron wavelength is demonstrated which uses a thin crystal plate of Bi12SiO20 with SiO2-Si:H-SiO2 phase matching films as the polarization converter. The switch has a drive voltage of 390 V and an extinction ratio of less than -20 dB. By reducing the crystal thickness from 100 to 50 microns, the drive voltage could be reduced by a factor of two; a further reduction could be obtained by optimizing the crystal orientation.
Design of high efficiency multi-GHz SiGe HBT electro-optic modulator.
Deng, Shengling; Huang, Z Rena; McDonald, J F
We design and theoretically analyze a heterojunction bipolar transistor (HBT) electro-optic (EO) modulator with a composition graded SiGe base. The waveguide has a large cross-section of 1 microm for ease of fiber alignment. At a base-emitter bias of V BE = 2.5 V, a pi-phase shift requires 74.5 microm interaction length for TM polarization at lambda = 1.55 microm. The total optical attenuation is 3.9 dB to achieve a pi-phase shift in this condition. This device is expected to operate at a switching speed of 2.4 GHz. PMID:19654748
Electro-optic Measurement of the Wake Fields of a Relativistic Electron Beam
Fitch, M. J.; Melissinos, A. C.; Colestock, P. L.; Carneiro, J.-P.; Edwards, H. T.; Hartung, W. H.
When a relativistic electron bunch traverses a structure, strong electromagnetic fields are induced in its wake. For a 12 nC bunch of duration 4.2ps FWHM, the peak field is measured >0.5 MV/m . Time resolution of {approx}5 ps is achieved using electro-optic sampling with a lithium tantalate (LiTaO{sub 3}) crystal and a short-pulse infrared laser synchronized to the beam. We present measurements for both the longitudinal and radial components of the field and relate them to the wall impedance.
Electro-optic detection of continuous-wave mid-infrared radiation
NASA Astrophysics Data System (ADS)
Cao, Hua; Nahata, Ajay
We demonstrate coherent detection of continuous-wave mid-infrared radiation. This radiation is produced by use of conventional difference-frequency mixing and detected via the linear electro-optic effect. The detection process allows for the simultaneous measurement of the amplitude and phase properties of the infrared field. Both processes require an amplitude-modulated optical beam that is derived from the superimposed output of two single-frequency lasers. With appropriate choice of lasers and nonlinear optical crystals, the technique may be applied to any wavelength throughout the far and mid infrared.
Phase polymorphism and electro-optical properties of a ferroelectric liquid crystal containing the biphenyl system
NASA Astrophysics Data System (ADS)
Zalewski, Sławomir; Ossowska-Chruściel, Mirosława D.
In this article we present results concerning phase transitions and physical properties of the ferroelectric phase of the compound (S)-4-(1-methylheptyloxy)biphenyl-4'-(heptyloxy phenyl)-4-carboxylate (MHOBOPO7). The compound has the following phases: smectic ferroelectric C (SmC*), chiral nematic N*, and two defected phases, TGBC and blue phase. The mesomorphic properties were investigated by means of three complementary methods: differential scanning calorimetry, polarizing light optical microscopy, and transmitted light intensity. The electro-optical measurements were carried out on an ordered sample in a middle electric field during very slow cooling from the nematic phase to the ferroelectric phase.
Effects of graphene on electro-optic switching and spontaneous polarization of a ferroelectric liquid crystal
Basu, Rajratan
A small quantity of graphene flakes was doped in a ferroelectric liquid crystal (FLC), and the field-induced ferroelectric electro-optic switching was found to be significantly faster in the FLC + graphene hybrid than that of the pure FLC. Further studies revealed that the suspended graphene flakes enhanced the FLC's spontaneous polarization by improving smectic-C ordering resulting from the π–π electron stacking, and reduced rotation viscosity by trapping some of the free ions of the FLC media. These effects coherently impacted the FLC-switching phenomenon, enabling the FLC molecules to switch faster on reversing an external electric field.
Injected-charge-driven increase in electro-optic effect of KTN crystals
Toyoda, Seiji; Imai, Tadayuki; Miyazu, Jun; Okabe, Yuichi; Ueno, Masahiro; Kobayashi, Junya
We report a significant increase in the electro-optic (EO) effect of KTa{sub x}Nb{sub 1-x}O{sub 3} (KTN) crystals that we achieved by injecting carriers into them. The dielectric constant of KTN was increased approximately twofold by carrier injection. The EO beam scanning performance was effectively improved by the increase in the EO effect resulting from the increased dielectric constant. The estimated densities of the trapped electrons were as small as 5.8 × 10{sup 20}m{sup -3}. The very small quantity of injected electrons greatly affected the dielectric constant and EO effect of the KTN crystals.
Electro-optic switching in phase-discontinuity complementary metasurface twisted nematic cell.
Lee, Y U; Kim, J; Woo, J H; Bang, L H; Choi, E Y; Kim, E S; Wu, J W
Electro-optic switching of refraction is experimentally demonstrated in a phase-discontinuity complementary metasurface twisted nematic cell. The phase-discontinuity complementary metasurface is fabricated by focused-ion-beam milling, and a twisted nematic cell is constructed with complementary V-shape slot antenna metasurface. By application of an external voltage, switching is achieved between ordinary refraction and extraordinary refraction satisfying the generalized Snell's law. It has a strong implication for applications in spatial light modulation and wavelength division multiplexer/demultiplexer in a near-IR spectral range. PMID:25321285
Conversion Efficiency, Spectral And Mode Purities Of A Single Sideband Electro-Optic Modulator
NASA Astrophysics Data System (ADS)
Eng, R. S.; Parker, J. K.; Bunis, J. L.; Grimm, J. G.; Harris, N. W.; Wong, D. M.
The measured single sideband conversion efficiency of a 10.6 μm bulk-type CdTe electro-optic modulator over the 14-18 GHz modulation frequency range is shown to be in close agreement with the coupled-mode and segmented modulator theories. The paper addresses the effects of the rotational orientations of segmented crystals and indirectly proves that a broadband multisection modulator is feasible; it further shows that a modulator with crystals in rotatable segmented circular waveguides is spectrally widely tunable. The effects of mechanical pressure and off-axis beam propagation on conver-sion, mode purity, and beam quality are also discussed.
An electro-optic modulator-assisted wavevector-resolving Brillouin light scattering setup.
Neumann, T; Schneider, T; Serga, A A; Hillebrands, B
Brillouin light scattering spectroscopy is a powerful technique which incorporates several extensions such as space-, time-, phase-, and wavevector-resolution. Here, we report on the improvement of the wavevector-resolving setup by including an electro-optic modulator. This provides a reference to calibrate the position of the diaphragm hole which is used for wavevector selection. The accuracy of this calibration is only limited by the accuracy of the wavevector measurement itself. To demonstrate the validity of the approach the wavevectors of dipole-dominated spin waves excited by a microstrip antenna were measured. PMID:19485518
Electro-optic system for online light transmission control of polymer-dispersed liquid crystal windows
NASA Astrophysics Data System (ADS)
Sanchez-Pena, Jose M.; Vazquez, Carmen; Perez, I.; Rodriguez, Inmaculada; Oton, Jose M.
Polymer-dispersed liquid crystals (PDLCs) are formed by microdroplets of liquid crystal embedded in a flexible matrix and sandwiched between transparent electrodes. Large area units (several square meters) can be easily prepared. Opaque, transparent, and intermediate light transmission states can be achieved by applying appropriate electric fields. These features allow their use in active windows for illumination, greenhouse regulation, and privacy, both on buildings and vehicles. An electro-optic system based on a microcontrolled driver was implemented for on-line control of PDLC windows. The system may self-regulate daylight or may be used as remote control.
High-Q lithium niobate microdisk resonators on a chip for efficient electro-optic modulation.
Wang, Jie; Bo, Fang; Wan, Shuai; Li, Wuxia; Gao, Feng; Li, Junjie; Zhang, Guoquan; Xu, Jingjun
Lithium niobate (LN) microdisk resonators on a LN-silica-LN chip were fabricated using only conventional semiconductor fabrication processes. The quality factor of the LN resonator with a 39.6-μm radius and a 0.5-μm thickness is up to 1.19 × 10(6), which doubles the record of the quality factor 4.84 × 10(5) of LN resonators produced by microfabrication methods allowing batch production. Electro-optic modulation with an effective resonance-frequency tuning rate of 3.0 GHz/V was demonstrated in the fabricated LN microdisk resonator. PMID:26368411
External electro-optic probing of millimeter-wave integrated circuits
NASA Technical Reports Server (NTRS)
Whitaker, J. F.; Valdmanis, J. A.; Jackson, T. A.; Bhasin, K. B.; Romanofsky, Robert R.; Mourou, G. A.
An external, noncontact electro-optic measurement system, designed to operate at the wafer level with conventional wafer probing equipment and without any special circuit preparation, has been developed. Measurements have demonstrated the system's ability to probe continuous and pulsed signals on microwave integrated circuits on arbitrary substrates with excellent spatial resolution. Experimental measurements on a variety of digital and analog circuits, including a GaAs selectively-doped heterostructure transistor prescaler, an NMOS silicon multiplexer, and a GaAs power amplifier MMIC are reported.
Influence of gold nanorods size on electro-optical and dielectric properties of ferroelectric liquid crystals
Podgornov, Fedor V.; Ryzhkova, Anna V.; Haase, Wolfgang
The influence of the gold nanorods (GNRs) diameter on the electro-optic and dielectric properties of the ferroelectric liquid crystals (FLCs) was investigated. It was shown that dispersing of GNRs in FLCs could lead to an increase of the internal electric field inside the liquid crystalline layer. This effect results in a significant decrease of the switching time and the rotational viscosity of the FLC/GNRs nanodispersions independently on the GNRs diameter. Oppositely, the relaxation frequency and the dielectric strength of the Goldstone mode strongly depend on the GNRs diameter, which can be explained by the charge transfer between the GNRs and FLC molecules.
Hybrid electro-optic plasmonic modulators based on directional coupler switches
NASA Astrophysics Data System (ADS)
Zografopoulos, Dimitrios C.; Swillam, Mohamed A.; Shahada, Lamees A.; Beccherelli, Romeo
By breaking the diffraction limit, plasmonics enable the miniaturization of integrated optical signal processing units in a platform compatible with traditional CMOS technology. In such architectures, modulators and switches are essential elements for fast and low-power optical signal processing. This work presents the design of a CMOS-compatible hybrid plasmonic modulator based on directional couplers enhanced with a layer of electro-optic polymer. The modulator shows very broad operating window with low crosstalk values and very small footprint with respect to similar couplers and switches of the silicon photonics platform.
Accurate determination of the diffusion coefficient of proteins by Fourier analysis with whole column imaging detection.
Zarabadi, Atefeh S; Pawliszyn, Janusz
Analysis in the frequency domain is considered a powerful tool to elicit precise information from spectroscopic signals. In this study, the Fourier transformation technique is employed to determine the diffusion coefficient (D) of a number of proteins in the frequency domain. Analytical approaches are investigated for determination of D from both experimental and data treatment viewpoints. The diffusion process is modeled to calculate diffusion coefficients based on the Fourier transformation solution to Fick's law equation, and its results are compared to time domain results. The simulations characterize optimum spatial and temporal conditions and demonstrate the noise tolerance of the method. The proposed model is validated by its application for the electropherograms from the diffusion path of a set of proteins. Real-time dynamic scanning is conducted to monitor dispersion by employing whole column imaging detection technology in combination with capillary isoelectric focusing (CIEF) and the imaging plug flow (iPF) experiment. These experimental techniques provide different peak shapes, which are utilized to demonstrate the Fourier transformation ability in extracting diffusion coefficients out of irregular shape signals. Experimental results confirmed that the Fourier transformation procedure substantially enhanced the accuracy of the determined values compared to those obtained in the time domain. PMID:25607375
Remote Fourier transform-infrared spectral imaging system with hollow-optical fiber bundle.
Huang, Chenhui; Kino, Saiko; Katagiri, Takashi; Matsuura, Yuji
A spectral imaging system consisting of a Fourier transform-infrared spectrometer, a high-speed infrared camera, and a bundle of hollow-optical fibers transmitting infrared radiation images was constructed. Infrared transmission spectra were obtained by carefully processing multiple interferograms taken by high-speed photography. Infrared spectral images of a variety of samples captured by the system were measured. We successfully detected existence maps of the oil and fat of biological samples by mapping the transmission of specific wavelengths in the spectrum. PMID:23052066
High-SNR static Fourier-transform imaging spectrometer based on differential structure
NASA Astrophysics Data System (ADS)
Jin, Peng; Zhu, Shuaishuai; Zhang, Yu; Lin, Jie
Fourier-transform imaging spectrometers are rapidly developed due to their extensive use in industrial monitoring, target detection, and chemical identification. Static Fourier-transform imaging spectrometer (SFIS) containing a birefringent interferometer is one of the most popular directions due to its inherent robustness. However, the SFIS suffers from its low achievable signal-to-noise ratio (SNR) because of the restriction of incident angle. Meanwhile, in applications, the SNR is perhaps the most important factor to determine the usefulness of an instrument. In this paper, we report here a Static Fourier-transform imaging spectrometer based on differential structure (SFIS-DS) in the 400-800nm wavelength range with a high SNR. As in electronic system, the differential structure can double optical efficiency and strongly restrain common mode error in the SFIS-DS. And the differential structure described here is also available for any instruments containing a birefringent interferometer. However, the drawback of the SFIS-DS is that the two images obtained by the two differential channels need precise registration which can be overcome by a sub-pixel spatial registration algorithm. The experimental results indicate the SFIS-DS can increase the SNR by no less than 40%.
Study on the algorithm of computational ghost imaging based on discrete fourier transform measurement matrix
NASA Astrophysics Data System (ADS)
Zhang, Leihong; Liang, Dong; Li, Bei; Kang, Yi; Pan, Zilan; Zhang, Dawei; Gao, Xiumin; Ma, Xiuhua
On the basis of analyzing the cosine light field with determined analytic expression and the pseudo-inverse method, the object is illuminated by a presetting light field with a determined discrete Fourier transform measurement matrix, and the object image is reconstructed by the pseudo-inverse method. The analytic expression of the algorithm of computational ghost imaging based on discrete Fourier transform measurement matrix is deduced theoretically, and compared with the algorithm of compressive computational ghost imaging based on random measurement matrix. The reconstruction process and the reconstruction error are analyzed. On this basis, the simulation is done to verify the theoretical analysis. When the sampling measurement number is similar to the number of object pixel, the rank of discrete Fourier transform matrix is the same as the one of the random measurement matrix, the PSNR of the reconstruction image of FGI algorithm and PGI algorithm are similar, the reconstruction error of the traditional CGI algorithm is lower than that of reconstruction image based on FGI algorithm and PGI algorithm. As the decreasing of the number of sampling measurement, the PSNR of reconstruction image based on FGI algorithm decreases slowly, and the PSNR of reconstruction image based on PGI algorithm and CGI algorithm decreases sharply. The reconstruction time of FGI algorithm is lower than that of other algorithms and is not affected by the number of sampling measurement. The FGI algorithm can effectively filter out the random white noise through a low-pass filter and realize the reconstruction denoising which has a higher denoising capability than that of the CGI algorithm. The FGI algorithm can improve the reconstruction accuracy and the reconstruction speed of computational ghost imaging.
Fourier-interpolation superresolution optical fluctuation imaging (fSOFi) (Conference Presentation)
NASA Astrophysics Data System (ADS)
Enderlein, Joerg; Stein, Simon C.; Huss, Anja; Hähnel, Dirk; Gregor, Ingo
Stochastic Optical Fluctuation Imaging (SOFI) is a superresolution fluorescence microscopy technique which allows to enhance the spatial resolution of an image by evaluating the temporal fluctuations of blinking fluorescent emitters. SOFI is not based on the identification and localization of single molecules such as in the widely used Photoactivation Localization Microsopy (PALM) or Stochastic Optical Reconstruction Microscopy (STORM), but computes a superresolved image via temporal cumulants from a recorded movie. A technical challenge hereby is that, when directly applying the SOFI algorithm to a movie of raw images, the pixel size of the final SOFI image is the same as that of the original images, which becomes problematic when the final SOFI resolution is much smaller than this value. In the past, sophisticated cross-correlation schemes have been used for tackling this problem. Here, we present an alternative, exact, straightforward, and simple solution using an interpolation scheme based on Fourier transforms. We exemplify the method on simulated and experimental data.
Binary encoding method to encrypt Fourier-transformed information of digital images
NASA Astrophysics Data System (ADS)
Lin, Kuang Tsan
An encoding method is used to encrypt the Fourier-transformed information of a hidden (covert) digital image in an overt image, while the Fourier-transformed information must be encoded with binary codes. All of the pixels in an overt image are classified into five groups that are called identification, type, tracing, dimension, and information codes. Identification codes are used to judge if the overt image contains codes that belong to the proposed encoding method or not; type codes are used to judge the encoding type; tracing codes are used to judge the encoding trace; dimension codes are used to judge the size of the hidden information; and information codes are used to decode the hidden information. Applying the proposed encoding method is rather easy, and host images corresponding to overt images are not needed for decoding work. The experiment has demonstrated four types of encoding for the proposed encoding method to reconstruct covert images without any distortion or only with a little distortion.
Development of a multi-Fourier-transform interferometer: imaging experiments in millimeter and submillimeter wave bands.
Ohta, Izumi S; Hattori, Makoto; Matsuo, Hiroshi
We have developed a millimeter and submillimeter Michelson-type bolometric interferometer based on a Martin-Puplett-type Fourier-transform spectrometer named multi-Fourier-transform interferometer (MuFT). We have succeeded in proving that the MuFT is capable of performing broadband imaging observations as theoretically proposed by our previous paper (OHM) [Appl. Opt. 45, 2576 (2006)]. We succeeded in acquiring the mutual coherence signal for an extended source in broadband. By analyzing the obtained mutual coherence signal following the formula proposed in OHM, 2D source images for each wavenumber from 5 cm(-1) (150 GHz) to 35 cm(-1) (1.05 THz) with a wavenumber interval of 0.4 cm(-1) (12 GHz) were successfully extracted. The large dynamic range advantage of the MuFT proposed in OHM was confirmed experimentally. PMID:17514233
Nonnegative image reconstruction from sparse Fourier data: a new deconvolution algorithm
NASA Astrophysics Data System (ADS)
Bonettini, S.; Prato, M.
This paper deals with image restoration problems where the data are nonuniform samples of the Fourier transform of the unknown object. We study the inverse problem in both semidiscrete and fully discrete formulations, and our analysis leads to an optimization problem involving the minimization of the data discrepancy under nonnegativity constraints. In particular, we show that such a problem is equivalent to a deconvolution problem in the image space. We propose a practical algorithm, based on the gradient projection method, to compute a regularized solution in the discrete case. The key point in our deconvolution-based approach is that the fast Fourier transform can be employed in the algorithm implementation without the need of preprocessing the data. A numerical experimentation on simulated and real data from the NASA RHESSI mission is also performed.
Effect of surface anchoring energy on electro-optic characteristics of a fringe-field switching liquid crystal cell
NASA Astrophysics Data System (ADS)
Kim, Jin Hyun; Kang, Wan Seok; Sol Choi, Han; Park, Kiwoong; Lee, Joong Hee; Yoon, Sangho; Yoon, Sukin; Lee, Gi-Dong; Lee, Seung Hee
Surface anchoring strength of the alignment layer on liquid crystal (LC) determines electro-optic characteristics in the LC devices. This paper investigates how azimuthal and polar anchoring strength affects the electro-optic performance of a fringe-field switching (FFS) mode associated with electrode structure, cell gap and dielectric anisotropy of the LC by numerical simulation. Our important findings in the FFS mode are that both azimuthal and polar anchoring energy can considerably affect the operating voltage and also maximum transmittance when using a LC with positive dielectric anisotropy; however, when using a LC with negative dielectric anisotropy only azimuthal anchoring energy affects electro-optic characteristics. The study proposes an optimal design of an alignment layer for maximizing transmittance in the FFS mode.
Effect of the fringe visibility on spectrum SNR of Fourier transform imaging spectrometer
NASA Astrophysics Data System (ADS)
Wang, Shuang; Bin, Xiangli; Jing, Juanjuan; Pi, Haifeng
The principle of Fourier transform spectrometer is based on the relationship of Fourier-Transform between interferogram and spectrum. The spectral information of Fourier transform imaging spectrometer (FTIS) reconstructed from raw interferogram by data processing. So there are two kinds of signal-to-noise ratio (SNR) to evaluate instrument performance, one regarding interferogram and the other regarding reconstructed spectrum. Because the raw interferogram is intuitive, the interferogram SNR is studied usually. On the contrary, the spectrum SNR is studied less because of the complexity of the data processing from interferogram to spectrum. The research about the effect of the interference fringe visibility on the spectrum SNR is especially few. This paper present a research work on the relations between the interference fringe visibility and the spectrum SNR. Firstly, the reduction of fringe visibility caused by imaging lens defocus was analyzed. Secondly, the changes of the average spectrum signal and noise caused by the reduction of fringe visibility were calculated. For average spectrum signal, the math deductions are done base on Fourier transform theory. The average noise with different input signal optic-electrons number are simulated. the results show that the average spectrum signal is directly proportional to the fringe visibility, and the effect of fringe visibility on the noise related to signal can be ignorable. Finally, In order to demonstrate above results, the imaging experiment was done with white-light source, using LASIS (Large aperture static imaging spectrometer) based on Sagnac Interferometer. The average spectrum SNRs under different fringe visibility are calculated and analyzed. The experimental results show that: the average spectrum SNRs increase from 42.7 to 62.4.along with the fringe visibility increasing from 0.5051 to 0.687. the reconstructed spectrum SNR is directly proportional to the fringe visibility. As a result, the interferogram
Image Reconstruction from Under sampled Fourier Data Using the Polynomial Annihilation Transform
Archibald, Richard K.; Gelb, Anne; Platte, Rodrigo
Fourier samples are collected in a variety of applications including magnetic resonance imaging and synthetic aperture radar. The data are typically under-sampled and noisy. In recent years, l1 regularization has received considerable attention in designing image reconstruction algorithms from under-sampled and noisy Fourier data. The underlying image is assumed to have some sparsity features, that is, some measurable features of the image have sparse representation. The reconstruction algorithm is typically designed to solve a convex optimization problem, which consists of a fidelity term penalized by one or more l1 regularization terms. The Split Bregman Algorithm provides a fast explicit solutionmore » for the case when TV is used for the l1l1 regularization terms. Due to its numerical efficiency, it has been widely adopted for a variety of applications. A well known drawback in using TV as an l1 regularization term is that the reconstructed image will tend to default to a piecewise constant image. This issue has been addressed in several ways. Recently, the polynomial annihilation edge detection method was used to generate a higher order sparsifying transform, and was coined the "polynomial annihilation (PA) transform." This paper adapts the Split Bregman Algorithm for the case when the PA transform is used as the l1 regularization term. In so doing, we achieve a more accurate image reconstruction method from under-sampled and noisy Fourier data. Our new method compares favorably to the TV Split Bregman Algorithm, as well as to the popular TGV combined with shearlet approach.« less
Image Reconstruction from Under sampled Fourier Data Using the Polynomial Annihilation Transform
Archibald, Richard K.; Gelb, Anne; Platte, Rodrigo
Fourier samples are collected in a variety of applications including magnetic resonance imaging and synthetic aperture radar. The data are typically under-sampled and noisy. In recent years, l1 regularization has received considerable attention in designing image reconstruction algorithms from under-sampled and noisy Fourier data. The underlying image is assumed to have some sparsity features, that is, some measurable features of the image have sparse representation. The reconstruction algorithm is typically designed to solve a convex optimization problem, which consists of a fidelity term penalized by one or more l1 regularization terms. The Split Bregman Algorithm provides a fast explicit solution for the case when TV is used for the l1l1 regularization terms. Due to its numerical efficiency, it has been widely adopted for a variety of applications. A well known drawback in using TV as an l1 regularization term is that the reconstructed image will tend to default to a piecewise constant image. This issue has been addressed in several ways. Recently, the polynomial annihilation edge detection method was used to generate a higher order sparsifying transform, and was coined the "polynomial annihilation (PA) transform." This paper adapts the Split Bregman Algorithm for the case when the PA transform is used as the l1 regularization term. In so doing, we achieve a more accurate image reconstruction method from under-sampled and noisy Fourier data. Our new method compares favorably to the TV Split Bregman Algorithm, as well as to the popular TGV combined with shearlet approach.
Low power Electro-optical filter: Constructed using silicon nanobeam resonator and PIN junction
NASA Astrophysics Data System (ADS)
Ebrahimy, Mehdi N.; Orafaei, Hamed; Andalib, Alireza; Alipuor-Banaei, Hamed
In this paper, a high tunable Electro-optical filter is designed and simulated with low electric power consumption. A silicon nanobeam resonator based on one-dimensional photonic crystal in the form of Fabry-Perot structure, silicon-on-insulator waveguide, is proposed with a PIN junction. In designing nanobeam resonator, "deterministic design method" is used to achieve the high quality factor and high-transmission rate. Tuning of the resonant wavelength in the output channel of the filter is achieved by manipulating the refractive index of the active area by using the free-carrier dispersion effect. The output wavelengths of designed device can be tuned for the telecom-friendly 1.55 μm range. The device shows a wavelength shift higher than 3 nm for a power consumption of only 0.9 mW. Finally, the simulation results show that the provided device can be considered as a narrowband and tunable Electro-optical filter that is suitable for DWDM communication system.
Electro-optic sampling for time resolving relativistic ultrafast electron diffraction
Scoby, C. M.; Musumeci, P.; Moody, J.; Gutierrez, M.; Tran, T.
The Pegasus laboratory at UCLA features a state-of-the-art electron photoinjector capable of producing ultrashort (<100 fs) high-brightness electron bunches at energies of 3.75 MeV. These beams recently have been used to produce static diffraction patterns from scattering off thin metal foils, and it is foreseen to take advantage of the ultrashort nature of these bunches in future pump-probe time-resolved diffraction studies. In this paper, single shot 2-d electro-optic sampling is presented as a potential technique for time of arrival stamping of electron bunches used for diffraction. Effects of relatively low bunch charge (a few 10's of pC) and modestly relativistic beams are discussed and background compensation techniques to obtain high signal-to-noise ratio are explored. From these preliminary tests, electro-optic sampling is suitable to be a reliable nondestructive time stamping method for relativistic ultrafast electron diffraction at the Pegasus lab.
Electro-optical equivalent calibration technology for high-energy laser energy meters.
Wei, Ji Feng; Chang, Yan; Sun, Li Qun; Zhang, Kai; Hu, Xiao Yang; Zhang, Wei
Electro-optical equivalent calibration with high calibration power and high equivalence is particularly well-suited to the calibration of high-energy laser energy meters. A large amount of energy is reserved during this process, however, which continues to radiate after power-off. This study measured the radiation efficiency of a halogen tungsten lamp during power-on and after power-off in order to calculate the total energy irradiated by a lamp until the high-energy laser energy meter reaches thermal equilibrium. A calibration system was designed based on the measurement results, and the calibration equivalence of the system was analyzed in detail. Results show that measurement precision is significantly affected by the absorption factor of the absorption chamber and by heat loss in the energy meter. Calibration precision is successfully improved by enhancing the equivalent power and reducing power-on time. The electro-optical equivalent calibration system, measurement uncertainty of which was evaluated as 2.4% (k = 2), was used to calibrate a graphite-cone-absorption-cavity absolute energy meter, yielding a calibration coefficient of 1.009 and measurement uncertainty of 3.5% (k = 2). A water-absorption-type high-energy laser energy meter with measurement uncertainty of 4.8% (k = 2) was considered the reference standard, and compared to the energy meter calibrated in this study, yielded a correction factor of 0.995 (standard deviation of 1.4%). PMID:27131714
T-shaped cavity dual-frequency Nd:YAG laser with electro-optical modulation
NASA Astrophysics Data System (ADS)
Xing, Junhong; Jiao, Mingxing; Liu, Yun
A T-shaped cavity dual-frequency Nd:YAG laser with electro-optical modulation is proposed, which consists of both p- and s-cavities sharing the same gain medium of Nd:YAG. Each cavity was not only able to select longitudinal mode but also tune frequency using an electro-optic birefringent filter polarization beam splitter + lithium niobate. The frequency difference of dual frequency was tuned through the whole gain bandwidth of Nd:YAG, which is far above the usually accepted free spectral range value in the case of a single-axis laser. As a result, the simultaneous operation of orthogonally and linearly polarized dual-frequency laser was obtained, which coincides with the theoretical analysis based on Jones matrices. The obtained frequency difference ranges from 0 to 132 GHz. This offers a simple and widely tunable source with potential for portable frequency reference applications in terahertz-wave generation and absolute-distance interferometry measurement areas.
Performance of an electro-optical solar compass in partially obscured Sun conditions.
Bollanti, S; De Meis, D; Di Lazzaro, P; Flora, F; Gallerano, G P; Mezi, L; Murra, D; Vicca, D
Solar compasses are designed to accurately find true North on sunny days. However, no data on their performance are available when sunlight is partially blocked, e.g., by a cloud. We have measured, for the first time to the best of our knowledge, the performance of one of the most accurate electro-optical solar compasses (accuracy better than 0.01 deg) as a function of the solar disk obscuration during the Sun's eclipse on 20 March 2015. The measurements show that the accuracy level is mainly dependent on the asymmetry of the obscuration with respect to the main axis of the optical detection system and, to a lesser extent, on the percentage of the solar disk covered. In particular, azimuth measurement suffered a maximum deviation of 0.08 deg when 35% of the solar disk was asymmetrically obscured. The deviation was smaller when 46% of the solar disk was more symmetrically obscured. This experiment demonstrates that, even in the case of a partially obscured Sun, the electro-optical solar compass maintains an accuracy better than magnetic and electronic compasses. PMID:27140077
Synthesis and characterization of cross-linkable polyurethane-imide electro-optic waveguide polymer
NASA Astrophysics Data System (ADS)
Wang, Long-De; Tang, Jie; Li, Ruo-Zhou; Zhang, Tong; Tong, Ling; Tang, Jing
The novel electro-optic (EO) polymers of fluorinated cross-linkable polyurethane-imides (CLPUI) were designed and synthesized by polycondensation of azo chromophore C1 and C2, diisocyanate MDI, and aromatic dianhydride 6FDA. Molecular structural characterization for the resulting polymers was achieved by 1HNMR, FT-IR, elemental analysis, and gel permeation chromatography. The polymers exhibit good film-forming properties, high glass transition temperature ( T g) in the range of 193-200 °C, and thermal stability up to 290 °C. The polymers that possess a high EO coefficient (γ_{33} = 48 and 56 pm/V) at 1550 nm for poled polymer thin films were measured by the simple reflection technique. Excellent temporal stability and low optical losses in the range of 1.1-1.7 dB/cm at 1550 nm were observed for these polymers. Using the synthesized side-chain electro-optic CLPUI as the active core material and of a fluorinated polyimide as cladding material, we have designed and successfully fabricated the high-performance polymer waveguide Mach-Zehnder EO modulators.
Electro-optical backplane demonstrator with integrated multimode gradient-index thin glass waveguide panel
NASA Astrophysics Data System (ADS)
Schröder, Henning; Brusberg, Lars; Pitwon, Richard; Whalley, Simon; Wang, Kai; Miller, Allen; Herbst, Christian; Weber, Daniel; Lang, Klaus-Dieter
Optical interconnects for data transmission at board level offer increased energy efficiency, system density, and bandwidth scalability compared to purely copper driven systems. We present recent results on manufacturing of electrooptical printed circuit board (PCB) with integrated planar glass waveguides. The graded index multi-mode waveguides are patterned inside commercially available thin-glass panels by performing a specific ion-exchange process. The glass waveguide panel is embedded within the layer stack-up of a PCB using proven industrial processes. This paper describes the design, manufacture, assembly and characterization of the first electro-optical backplane demonstrator based on integrated planar glass waveguides. The electro-optical backplane in question is created by laminating the glass waveguide panel into a conventional multi-layer electronic printed circuit board stack-up. High precision ferrule mounts are automatically assembled, which will enable MT compliant connectors to be plugged accurately to the embedded waveguide interfaces on the glass panel edges. The demonstration platform comprises a standardized sub-rack chassis and five pluggable test cards each housing optical engines and pluggable optical connectors. The test cards support a variety of different data interfaces and can support data rates of up to 32 Gb/s per channel.
Sol-Gel Material-Enabled Electro-Optic Polymer Modulators.
Himmelhuber, Roland; Norwood, Robert A; Enami, Yasufumi; Peyghambarian, Nasser
Sol-gels are an important material class, as they provide easy modification of material properties, good processability and are easy to synthesize. In general, an electro-optic (EO) modulator transforms an electrical signal into an optical signal. The incoming electrical signal is most commonly information encoded in a voltage change. This voltage change is then transformed into either a phase change or an intensity change in the light signal. The less voltage needed to drive the modulator and the lower the optical loss, the higher the link gain and, therefore, the better the performance of the modulator. In this review, we will show how sol-gels can be used to enhance the performance of electro-optic modulators by allowing for designs with low optical loss, increased poling efficiency and manipulation of the electric field used for driving the modulator. The optical loss is influenced by the propagation loss in the device, as well as the losses occurring during fiber coupling in and out of the device. In both cases, the use of sol-gel materials can be beneficial due to the wide range of available refractive indices and low optical attenuation. The influence of material properties and synthesis conditions on the device performance will be discussed. PMID:26225971
Single-shot electron bunch length measurements using a spatial electro-optical autocorrelation interferometer
NASA Astrophysics Data System (ADS)
Sütterlin, Daniel; Erni, Daniel; Schlott, Volker; Sigg, Hans; Jäckel, Heinz; Murk, Axel
A spatial, electro-optical autocorrelation (EOA) interferometer using the vertically polarized lobes of coherent transition radiation (CTR) has been developed as a single-shot electron bunch length monitor at an optical beam port downstream the 100 MeV preinjector LINAC of the Swiss Light Source. This EOA monitor combines the advantages of step-scan interferometers (high temporal resolution) [D. Mihalcea et al., Phys. Rev. ST Accel. Beams 9, 082801 (2006) and T. Takahashi and K. Takami, Infrared Phys. Technol. 51, 363 (2008)] and terahertz-gating technologies [U. Schmidhammer et al., Appl. Phys. B: Lasers Opt. 94, 95 (2009) and B. Steffen et al., Phys. Rev. ST Accel. Beams 12, 032802 (2009)] (fast response), providing the possibility to tune the accelerator with an online bunch length diagnostics. While a proof of principle of the spatial interferometer was achieved by step-scan measurements with far-infrared detectors, the single-shot capability of the monitor has been demonstrated by electro-optical correlation of the spatial CTR interference pattern with fairly long (500 ps) neodymium-doped yttrium aluminum garnet (Nd:YAG) laser pulses in a ZnTe crystal. In single-shot operation, variations of the bunch length between 1.5 and 4 ps due to different phase settings of the LINAC bunching cavities have been measured with subpicosecond time resolution.
Electro-optical study of the exposure of Azospirillum brasilense carbohydrate epitopes.
Guliy, Olga I; Matora, Larisa Yu; Dykman, Lev A; Staroverov, Sergey A; Burygin, Gennady L; Bunin, Viktor D; Burov, Andrei M; Ignatov, Oleg V
The exposure of Azospirillum brasilense carbohydrate epitopes was investigated by electro-optical analysis of bacterial cell suspensions. To study changes in the electro-optical (EO) properties of the suspensions, we used antibodies generated to the complete lipopolysaccharide of A. brasilense type strain Sp7 and also antibodies to the smooth and rough O polysaccharides of Sp7. After 18 hr of culture growth, the EO signal of the suspension treated with antibodies to smooth O polysaccharide was approximately 20% lower than that of the suspension treated with antibodies to complete lipopolysaccharide (control). After 72 hr of culture growth, the strongest EO signal was observed for the cells treated with antibodies to rough O polysaccharide (approximately 46% greater than the control), whereas for the cells treated with antibodies to smooth O polysaccharide, it was much lower (approximately 23% of the control). These data were confirmed by electron microscopy. The results of the study may have importance for the rapid evaluation of changes in lipopolysaccharide form in microbial biotechnology, when the antigenic composition of the bacterial surface requires close control. PMID:25273383
Electro-optical equivalent calibration technology for high-energy laser energy meters
NASA Astrophysics Data System (ADS)
Wei, Ji Feng; Chang, Yan; Sun, Li Qun; Zhang, Kai; Hu, Xiao Yang; Zhang, Wei
Electro-optical equivalent calibration with high calibration power and high equivalence is particularly well-suited to the calibration of high-energy laser energy meters. A large amount of energy is reserved during this process, however, which continues to radiate after power-off. This study measured the radiation efficiency of a halogen tungsten lamp during power-on and after power-off in order to calculate the total energy irradiated by a lamp until the high-energy laser energy meter reaches thermal equilibrium. A calibration system was designed based on the measurement results, and the calibration equivalence of the system was analyzed in detail. Results show that measurement precision is significantly affected by the absorption factor of the absorption chamber and by heat loss in the energy meter. Calibration precision is successfully improved by enhancing the equivalent power and reducing power-on time. The electro-optical equivalent calibration system, measurement uncertainty of which was evaluated as 2.4% (k = 2), was used to calibrate a graphite-cone-absorption-cavity absolute energy meter, yielding a calibration coefficient of 1.009 and measurement uncertainty of 3.5% (k = 2). A water-absorption-type high-energy laser energy meter with measurement uncertainty of 4.8% (k = 2) was considered the reference standard, and compared to the energy meter calibrated in this study, yielded a correction factor of 0.995 (standard deviation of 1.4%).
Portable electro-optic device for performing serviceability check on IR guided missiles
NASA Astrophysics Data System (ADS)
Maini, A. K.; Agrawal, V.
Electro-optically guided weapons are the most potent and widely used munitions on land-based, aerial and ship-borne platforms because of their proven precision strike capability. Two such guided weapon categories include the IR guided surface-to-air and air-to-air missiles and laser guided bombs and missiles. The efficacy of the mission is critically dependent on the successful deployment of the weapon. This not only necessitates that periodic functionality check be carried out on these weapons, it should also be possible to perform functionality check also known as serviceability check even after they are strapped on to the launch platform. Serviceability check in the strap-on condition ensures a much higher hit probability. This paper presents the design and development of a portable electro-optic device that generates IR signatures in 3-5-µm band having the desired amplitude and spectral shape to match the IR signatures of target aircraft. A prototype was built using the proposed concept. The prototype was characterized in terms of its output amplitude and wavelength spectrum. The prototype was used to perform serviceability check on IR seekers of foreign origin. Test results are presented in the paper.
Controlling Fringe Sensitivity of Electro-Optic Holography Systems Using Laser Diode Current Modulation
NASA Technical Reports Server (NTRS)
Bybee, Shannon J.
Electro-Optic Holography (EOH) is a non-intrusive, laser-based, displacement measurement technique capable of static and dynamic displacement measurements. EOH is an optical interference technique in which fringe patterns that represent displacement contour maps are generated. At excessively large displacements the fringe density may be so great that individual fringes are not resolvable using typical EOH techniques. This thesis focuses on the development and implementation of a method for controlling the sensitivity of the EOH system. This method is known as Frequency Translated Electro-Optic Holography (FTEOH). It was determined that by modulating the current source of the laser diode at integer multiples of the object vibration, the fringe pattern is governed by higher order Bessel function of the first kind and the number of fringes that represent a given displacement can be controlled. The reduction of fringes is theoretically unlimited but physically limited by the frequency bandwidth of the signal generator, providing modulation to the laser diode. Although this research technique has been verified theoretically and experimentally in this thesis, due to the current laser diode capabilities it is a tedious and time consuming process to acquire data using the FTEOH technique.
Electro-optical logic gates based on graphene-silicon waveguides
NASA Astrophysics Data System (ADS)
Chen, Weiwei; Yang, Longzhi; Wang, Pengjun; Zhang, Yawei; Zhou, Liqiang; Yang, Tianjun; Wang, Yang; Yang, Jianyi
In this paper, designs of electro-optical AND/NAND, OR/ NOR, XOR/XNOR logic gates based on cascaded silicon graphene switches and regular 2×1 multimode interference combiners are presented. Each switch consists of a Mach-Zehnder interferometer in which silicon slot waveguides embedded with graphene flakes are designed for phase shifters. High-speed switching function is achieved by applying an electrical signal to tune the Fermi levels of graphene flakes causing the variation of modal effective index. Calculation results show the crosstalk in the proposed optical switch is lower than -22.9 dB within a bandwidth from 1510 nm to 1600 nm. The designed six electro-optical logic gates with the operation speed of 10 Gbit/s have a minimum extinction ratio of 35.6 dB and a maximum insertion loss of 0.21 dB for transverse electric modes at 1.55 μm.
Single-shot electron bunch length measurements using a spatial electro-optical autocorrelation interferometer
Suetterlin, Daniel; Erni, Daniel; Schlott, Volker; Sigg, Hans; Jaeckel, Heinz; Murk, Axel
A spatial, electro-optical autocorrelation (EOA) interferometer using the vertically polarized lobes of coherent transition radiation (CTR) has been developed as a single-shot electron bunch length monitor at an optical beam port downstream the 100 MeV preinjector LINAC of the Swiss Light Source. This EOA monitor combines the advantages of step-scan interferometers (high temporal resolution) [D. Mihalcea et al., Phys. Rev. ST Accel. Beams 9, 082801 (2006) and T. Takahashi and K. Takami, Infrared Phys. Technol. 51, 363 (2008)] and terahertz-gating technologies [U. Schmidhammer et al., Appl. Phys. B: Lasers Opt. 94, 95 (2009) and B. Steffen et al., Phys. Rev. ST Accel. Beams 12, 032802 (2009)] (fast response), providing the possibility to tune the accelerator with an online bunch length diagnostics. While a proof of principle of the spatial interferometer was achieved by step-scan measurements with far-infrared detectors, the single-shot capability of the monitor has been demonstrated by electro-optical correlation of the spatial CTR interference pattern with fairly long (500 ps) neodymium-doped yttrium aluminum garnet (Nd:YAG) laser pulses in a ZnTe crystal. In single-shot operation, variations of the bunch length between 1.5 and 4 ps due to different phase settings of the LINAC bunching cavities have been measured with subpicosecond time resolution.
Impact of lateral carrier confinement on electro-optical tuning properties of polariton condensates
Brodbeck, S.; Suchomel, H.; Amthor, M.; Wolf, A.; Kamp, M.; Schneider, C.; Höfling, S.
Electro-optical measurements on exciton-polaritons below and above the condensation threshold are performed on high quality, pin-doped microcavities with embedded GaAs quantum wells. Applying an external electric field shifts the polariton emission by hundreds of μeV both in the linear and the nonlinear regime. We study three device geometries to investigate the influence of carrier confinement in the plane of the quantum well on the electro-optical tuning properties. In the conventional micropillar geometry, the electric field tuning behavior is dominated by the effects of carrier tunneling and electric field screening that manifest in a blueshift of the polariton emission. In stark contrast, for a planar sample geometry, we can significantly extend the range of electric fields and a redshift is observed. To separate the contributions of quantum confined Stark effect and reduced exciton oscillator strength to the energy shift, we study a third sample where the etching of micropillars is stopped just above the active region. In this semi-planar geometry, exciton and polariton emissions can be measured simultaneously. As for the planar geometry, redshifts of the polariton emission are observed below and above threshold that are well reproduced by theoretical shifts.
Full-field absolute phase measurements in the heterodyne interferometer with an electro-optic modulator
NASA Astrophysics Data System (ADS)
Chen, Y. L.; Hsieh, H. C.; Wu, W. T.; Su, D. C.
A novel method for full-field absolute phase measurements in the heterodyne interferometer with an electro-optic modulator is proposed in this paper. Instead of the commonly-used half-wave voltage to drive the electro-optic modulator, a saw-tooth voltage signal with the amplitude being lower than its half-wave voltage is used. The interference signals become a group of periodical sinusoidal segments. The initial phase of each sinusoidal segment depends on the phase difference induced by the test sample. In real measurements, each segment is taken by a fast camera and becomes discrete digital points. After a series of operations, the starting point of the sampled sinusoidal segment can be determined accurately. Next, the period of the sampled sinusoidal segments is lengthened and they can be modified to a continuous sinusoidal wave by using a least-square sine fitting algorithm. The initial phase of the continuous sinusoidal wave can also be estimated. Subtracting the characteristic phase of the modulator from the initial phase, the absolute phase measured at the pixel can be obtained without the conventional reference signals. These operations are applied to other pixels, and the full-field absolute phase measurements can be achieved. The phase retardation of a quarter-wave plate is measured to show the validity of this method.
Wideband THz Time Domain Spectroscopy based on Optical Rectification and Electro-Optic Sampling
Tomasino, A.; Parisi, A.; Stivala, S.; Livreri, P.; Cino, A. C.; Busacca, A. C.; Peccianti, M.; Morandotti, R.
We present an analytical model describing the full electromagnetic propagation in a THz time-domain spectroscopy (THz-TDS) system, from the THz pulses via Optical Rectification to the detection via Electro Optic-Sampling. While several investigations deal singularly with the many elements that constitute a THz-TDS, in our work we pay particular attention to the modelling of the time-frequency behaviour of all the stages which compose the experimental set-up. Therefore, our model considers the following main aspects: (i) pump beam focusing into the generation crystal; (ii) phase-matching inside both the generation and detection crystals; (iii) chromatic dispersion and absorption inside the crystals; (iv) Fabry-Perot effect; (v) diffraction outside, i.e. along the propagation, (vi) focalization and overlapping between THz and probe beams, (vii) electro-optic sampling. In order to validate our model, we report on the comparison between the simulations and the experimental data obtained from the same set-up, showing their good agreement. PMID:24173583
Sol-Gel Material-Enabled Electro-Optic Polymer Modulators
Himmelhuber, Roland; Norwood, Robert A.; Enami, Yasufumi; Peyghambarian, Nasser
Sol-gels are an important material class, as they provide easy modification of material properties, good processability and are easy to synthesize. In general, an electro-optic (EO) modulator transforms an electrical signal into an optical signal. The incoming electrical signal is most commonly information encoded in a voltage change. This voltage change is then transformed into either a phase change or an intensity change in the light signal. The less voltage needed to drive the modulator and the lower the optical loss, the higher the link gain and, therefore, the better the performance of the modulator. In this review, we will show how sol-gels can be used to enhance the performance of electro-optic modulators by allowing for designs with low optical loss, increased poling efficiency and manipulation of the electric field used for driving the modulator. The optical loss is influenced by the propagation loss in the device, as well as the losses occurring during fiber coupling in and out of the device. In both cases, the use of sol-gel materials can be beneficial due to the wide range of available refractive indices and low optical attenuation. The influence of material properties and synthesis conditions on the device performance will be discussed. PMID:26225971
Electro-optic voltage sensor for sensing voltage in an E-field
Davidson, James R.; Crawford, Thomas M.; Seifert, Gary D.
A miniature electro-optic voltage sensor and system capable of accurate operation at high voltages has a sensor body disposed in an E-field. The body receives a source beam of electromagnetic radiation. A polarization beam displacer separates the source light beam into two beams with orthogonal linear polarizations. A wave plate rotates the linear polarization to rotated polarization. A transducer utilizes Pockels electro-optic effect and induces a differential phase shift on the major and minor axes of the rotated polarization in response to the E-field. A prism redirects the beam back through the transducer, wave plate, and polarization beam displacer. The prism also converts the rotated polarization to circular or elliptical polarization. The wave plate rotates the major and minor axes of the circular or elliptical polarization to linear polarization. The polarization beam displacer separates the beam into two beams of orthogonal linear polarization representing the major and minor axes. The system may have a transmitter for producing the beam of electro-magnetic radiation; a detector for converting the two beams into electrical signals; and a signal processor for determining the voltage.
Reconstruction of piecewise homogeneous images from partial knowledge of their Fourier Transform
NASA Astrophysics Data System (ADS)
Féron, Olivier; Chama, Zouaoui; Mohammad-Djafari, Ali
Fourier synthesis (FS) inverse problem consists in reconstructing a multi-variable function from the measured data which correspond to partial and uncertain knowledge of its Fourier Transform (FT). By partial knowledge we mean either partial support and/or the knowledge of only the module and by uncertain we mean both uncertainty of the model and noisy data. This inverse problem arises in many applications such as : optical imaging, radio astronomy, magnetic resonance imaging (MRI) and diffraction scattering (ultrasounds or microwave imaging). Most classical methods of inversion are based on interpolation of the data and fast inverse FT. But when the data do not fill uniformly the Fourier domain or when the phase of the signal is lacking as in optical interferometry, the results obtained by such methods are not satisfactory, because these inverse problems are ill-posed. The Bayesian estimation approach, via an appropriate modeling of the unknown functions gives the possibility of compensating the lack of information in the data, thus giving satisfactory results. In this paper we study the case where the observations are a part of the FT modulus of objects which are composed of a few number of homogeneous materials. To model such objects we use a Hierarchical Hidden Markov Modeling (HMM) and propose a Bayesian inversion method using appropriate Markov Chain Monte Carlo (MCMC) algorithms.
H-infinity mix sensitivity controller design based on GIMC for electro-optical stabilization and tracking system
NASA Astrophysics Data System (ADS)
Liu, Zi-dong; Bao, Qi-liang; Xia, Yunxia; Liu, Xiang
Electro-optical stabilization and tracking system is critical and difficult issue in satellite laser communication. Moreover, line-of-sight stabilized system is the kernel of implementing electro-optical stabilization and tracking system, which can be used to isolate the vibration of the moving platform of the satellite and the disturbance of the space environment. In this paper, we propose a new method, which using H∞ mix sensitivity based on generalized internal model controller (GIMC), to design the control system of the electro-optical stabilized platform. It is well known that there is an intrinsic conflict between performance and robustness in the standard feedback framework. Generalized internal model controller is a new architecture which can separate the performance and robustness design in controller design. This architecture has two parts: a high performance controller, say K0,which is designed by PI controller in this paper, and then a robustification controller, say Q, which is designed to improve the ability of the anti disturbance by using H-infinity mix sensitivity controller design method. In this paper, we also present the steps of controller design by using this method to make it easier to use. Based on the proposed method, numerical simulation and experiment are both carried out for a gyro stabilized platform of electro-optical tacking system. Both the numerical simulated and the experimental results show that the electro-optical stabilized platform using the H-infinity mix sensitivity controller design method based on GIMC is accurate and effective. Comparing with the same PI controller in standard feedback framework, the proposed method can guarantee the high tracking performance as same as the PI controller and improve the external disturbance restraining ability a lot. In conclusion, H-infinity mix sensitivity controller design method based on GIMC is a new approach for gyro stabilized platform of electro-optical stabilization and tracking
Optimized multiplexing super resolution imaging based on a Fourier ptychographic microscope
NASA Astrophysics Data System (ADS)
Sun, Jiasong; Chen, Qian; Zhang, Yuzhen; Zuo, Chao; Feng, Shijie; Hu, Yan; Zhang, Jialin
Fourier ptychographic microscopy (FPM) is a recently developed super-resolution technique by using angularly varying illumination and a phase retrieval algorithm to surpass the diffraction limit of the objective lens. To be specific, FP captures a set of low-resolution (LR) images under angularly varying illuminations, and combines them into one high-resolution (HR) image in the Fourier domain. However, the long capturing process becomes an obvious limitation since there are large number of images need to be acquired. Furthermore, the time can be increased several times over in order to acquire high-dynamic range images. Utilizing the multiplexing principle, we propose an optimized multiplexing FP algorithm, which is highly efficient, to shorten the exposure time of each raw image in this work. High acquisition efficiency is achieved by employing two set of optimized multiplexing patterns for bright-field and dark-field imaging respectively. Experimental results demonstrated that this method could improve the quality of reconstructed HR intensity distributions in a faster measuring process.
Single-channel color image encryption using phase retrieve algorithm in fractional Fourier domain
NASA Astrophysics Data System (ADS)
Sui, Liansheng; Xin, Meiting; Tian, Ailing; Jin, Haiyan
A single-channel color image encryption is proposed based on a phase retrieve algorithm and a two-coupled logistic map. Firstly, a gray scale image is constituted with three channels of the color image, and then permuted by a sequence of chaotic pairs generated by the two-coupled logistic map. Secondly, the permutation image is decomposed into three new components, where each component is encoded into a phase-only function in the fractional Fourier domain with a phase retrieve algorithm that is proposed based on the iterative fractional Fourier transform. Finally, an interim image is formed by the combination of these phase-only functions and encrypted into the final gray scale ciphertext with stationary white noise distribution by using chaotic diffusion, which has camouflage property to some extent. In the process of encryption and decryption, chaotic permutation and diffusion makes the resultant image nonlinear and disorder both in spatial domain and frequency domain, and the proposed phase iterative algorithm has faster convergent speed. Additionally, the encryption scheme enlarges the key space of the cryptosystem. Simulation results and security analysis verify the feasibility and effectiveness of this method.
Evaluation of Fourier transform coefficients for the diagnosis of rheumatoid arthritis from diffuse optical tomography images
NASA Astrophysics Data System (ADS)
Montejo, Ludguier D.; Jia, Jingfei; Kim, Hyun K.; Hielscher, Andreas H.
We apply the Fourier Transform to absorption and scattering coefficient images of proximal interphalangeal (PIP) joints and evaluate the performance of these coefficients as classifiers using receiver operator characteristic (ROC) curve analysis. We find 25 features that yield a Youden index over 0.7, 3 features that yield a Youden index over 0.8, and 1 feature that yields a Youden index over 0.9 (90.0% sensitivity and 100% specificity). In general, scattering coefficient images yield better one-dimensional classifiers compared to absorption coefficient images. Using features derived from scattering coefficient images we obtain an average Youden index of 0.58 +/- 0.16, and an average Youden index of 0.45 +/- 0.15 when using features from absorption coefficient images.
Adaptive anisotropic diffusion for noise reduction of phase images in Fourier domain Doppler optical coherence tomography.
Xia, Shaoyan; Huang, Yong; Peng, Shizhao; Wu, Yanfeng; Tan, Xiaodi
Phase image in Fourier domain Doppler optical coherence tomography offers additional flow information of investigated samples, which provides valuable evidence towards accurate medical diagnosis. High quality phase images are thus desirable. We propose a noise reduction method for phase images by combining a synthetic noise estimation criteria based on local noise estimator (LNE) and distance median value (DMV) with anisotropic diffusion model. By identifying noise and signal pixels accurately and diffusing them with different coefficients respectively and adaptive iteration steps, we demonstrated the effectiveness of our proposed method in both phantom and mouse artery images. Comparison with other methods such as filtering method (mean, median filtering), wavelet method, probabilistic method and partial differential equation based methods in terms of peak signal-to-noise ratio (PSNR), equivalent number of looks (ENL) and contrast-to-noise ratio (CNR) showed the advantages of our method in reserving image energy and removing noise. PMID:27570687
Depth resolved hyperspectral imaging spectrometer based on structured light illumination and Fourier transform interferometry.
Choi, Heejin; Wadduwage, Dushan; Matsudaira, Paul T; So, Peter T C
A depth resolved hyperspectral imaging spectrometer can provide depth resolved imaging both in the spatial and the spectral domain. Images acquired through a standard imaging Fourier transform spectrometer do not have the depth-resolution. By post processing the spectral cubes (x, y, λ) obtained through a Sagnac interferometer under uniform illumination and structured illumination, spectrally resolved images with depth resolution can be recovered using structured light illumination algorithms such as the HiLo method. The proposed scheme is validated with in vitro specimens including fluorescent solution and fluorescent beads with known spectra. The system is further demonstrated in quantifying spectra from 3D resolved features in biological specimens. The system has demonstrated depth resolution of 1.8 μm and spectral resolution of 7 nm respectively. PMID:25360367
Adaptive anisotropic diffusion for noise reduction of phase images in Fourier domain Doppler optical coherence tomography
Xia, Shaoyan; Huang, Yong; Peng, Shizhao; Wu, Yanfeng; Tan, Xiaodi
Phase image in Fourier domain Doppler optical coherence tomography offers additional flow information of investigated samples, which provides valuable evidence towards accurate medical diagnosis. High quality phase images are thus desirable. We propose a noise reduction method for phase images by combining a synthetic noise estimation criteria based on local noise estimator (LNE) and distance median value (DMV) with anisotropic diffusion model. By identifying noise and signal pixels accurately and diffusing them with different coefficients respectively and adaptive iteration steps, we demonstrated the effectiveness of our proposed method in both phantom and mouse artery images. Comparison with other methods such as filtering method (mean, median filtering), wavelet method, probabilistic method and partial differential equation based methods in terms of peak signal-to-noise ratio (PSNR), equivalent number of looks (ENL) and contrast-to-noise ratio (CNR) showed the advantages of our method in reserving image energy and removing noise. PMID:27570687
Fourier-processed images of dynamic lung function from list-mode data
Zubal, I.G.; Rowe, R.W.; Bizais, Y.; Susskind, H.; Bennett, G.W.; Brill, A.B.
Time and volume correlated amplitude and phase images are computed from nuclear medical ventilation studies and for dynamic transmission scans of the lungs. This is made possible by a hardware interface and data acquisition system, developed in-house, allowing camera events and multiple ancillary physiological signals (including lung volume) to be acquired simultaneously in list mode. The first harmonic amplitude and phase images are constructed on an event by event basis. These are computed for both equal time and equal lung volume increments. Time and volume correlated Fourier images for ventilation studies have shown details and functional structures not usually seen in conventional imaging techniques. Processed transmission scans show similar results compared to ventilation images.
Depth resolved hyperspectral imaging spectrometer based on structured light illumination and Fourier transform interferometry
Choi, Heejin; Wadduwage, Dushan; Matsudaira, Paul T.; So, Peter T.C.
A depth resolved hyperspectral imaging spectrometer can provide depth resolved imaging both in the spatial and the spectral domain. Images acquired through a standard imaging Fourier transform spectrometer do not have the depth-resolution. By post processing the spectral cubes (x, y, λ) obtained through a Sagnac interferometer under uniform illumination and structured illumination, spectrally resolved images with depth resolution can be recovered using structured light illumination algorithms such as the HiLo method. The proposed scheme is validated with in vitro specimens including fluorescent solution and fluorescent beads with known spectra. The system is further demonstrated in quantifying spectra from 3D resolved features in biological specimens. The system has demonstrated depth resolution of 1.8 μm and spectral resolution of 7 nm respectively. PMID:25360367
Perfusion and ventilation filters for Fourier-decomposition MR lung imaging.
Wujcicki, Artur; Corteville, Dominique; Materka, Andrzej; Schad, Lothar R
MR imaging without the use of contrast agents has recently been used for creating perfusion and ventilation functional lung images. The technique incorporates frequency- or wavelet-domain filters to separate the MR signal components. This paper presents a new, subject-adaptive algorithm for perfusion and ventilation filters design. The proposed algorithm uses a lung signal model for separation of the signal components in the frequency domain. Non-stationary lung signals are handled by a short time Fourier transform. This method was applied to sets of 192 and 90 co-registered non-contrast MR lung images measured for five healthy subjects at the rate of 3,33 images per second, using different slice thicknesses. In each case, the resulted perfusion and ventilation images showed a smaller amount of mutual information, when compared to those obtained using the known lowpass/highpass filter approach. PMID:25466452
Broadband terahertz characterization of the refractive index and absorption of some important polymeric and organic electro-optic materials
NASA Astrophysics Data System (ADS)
Cunningham, Paul D.; Valdes, Nestor N.; Vallejo, Felipe A.; Hayden, L. Michael; Polishak, Brent; Zhou, Xing-Hua; Luo, Jingdong; Jen, Alex K.-Y.; Williams, Jarrod C.; Twieg, Robert J.
We report broad bandwidth, 0.1-10 THz time-domain spectroscopy of linear and electro-optic polymers. The common THz optical component materials high-density polyethylene, polytetrafluoroethylene, polyimide (Kapton), and polyethylene cyclic olefin copolymer (Topas) were evaluated for broadband THz applications. Host polymers polymethyl methacrylate, polystyrene, and two types of amorphous polycarbonate were also examined for suitability as host for several important chromophores in guest-host electro-optic polymer composites for use as broadband THz emitters and sensors.
Slow-light enhanced electro-optic modulation with an on-chip silicon-hybrid Fano system.
Bera, Arijit; Roussey, Matthieu; Kuittinen, Markku; Honkanen, Seppo
We present the theoretical study of a coupled cavity system yielding a Fano response on a fully on-chip silicon platform hybridized with an electro-optic polymer. This novel Fano system is based on a slot waveguide Bragg grating geometry, enabling a huge enhancement of the electro-optic properties due to slow light effects at the resonance. The modulator shows a high resonance tunability of 1.75 nm/V and a low switching power of 0.63 V. Such a versatile system shows the promise for various nonlinear and active devices only by using suitable cover material. PMID:27176970
Reprint of: Coulomb field strength measurement by electro-optic spectral decoding system at the CALIFES beam line
NASA Astrophysics Data System (ADS)
Pan, R.; Jamison, S. P.; Lefevre, T.; Gillespie, W. A.
Electro-optic (EO) techniques are increasingly used for longitudinal bunch profile measurements. A bunch profile monitor, based on electro-optic spectral decoding (EOSD), has been developed and demonstrated on the CALIFES beam line at CERN. The EO response is analysed using a frequency domain description, and two methods for extraction of absolute Coulomb field strengths from the electron bunch are demonstrated. Measurements at field strengths up to 1.3 MV/m agree with the expectation based on independent charge measurements.
Electro-optical and dielectric properties of CdSe quantum dots and 6CHBT liquid crystals composites
Singh, U. B.; Pandey, M. B.; Dhar, R; Pandey, A. S.; Kumar, S.; Dabrowski, R.
We have prepared the composites of a room temperature nematic liquid crystal namely 4-(trans-4-n-hexylcyclohexyl) isothiocyanatobenzoate (6CHBT) and Cadmium Selenide Quantum Dots (CdSe-QDs) and investigated their electro-optical and dielectric properties. Effect of dispersion of CdSe-QDs on various electro-optical and display parameters of host liquid crystalline material have been studied. Physical parameters, such as switching threshold voltage and splay elastic constant have been altered drastically for composites. Dispersion of QDs in a liquid crystals medium destabilizes nematic ordering of the host and decreases the nematic-to-isotropic transition temperature.
Electro-optic millimeter-wave harmonic downconversion and vector demodulation using cascaded phase modulation and optical filtering.
Pagán, Vincent R; Murphy, Thomas E
We describe and demonstrate an electro-optic technique to simultaneously downconvert and demodulate vector-modulated millimeter-wave signals. The system uses electro-optic phase modulation and optical filtering to perform harmonic downconversion of the RF signal to an intermediate frequency (IF) or to baseband. We demonstrate downconversion of RF signals between 7 and 70-GHz to IFs below 20-GHz. Furthermore, we show harmonic downconversion and vector demodulation of 2.5-Gb/s QPSK and 5-Gb/s 16-QAM signals at carrier frequencies of 40-GHz to baseband. PMID:26030537
Ultrasonic imaging of an object at the presence of Fourier and non-Fourier transformation in the transmitted through the object acoustic field.
Andreeva, A; Burova, M; Burov, J
A metal object is computer visualized by registration of the amplitudes of the transmitted through the object short acoustic pulses. The pulses are separated by time, because of the presence of holes and internal compact components in the longitudinal section (structure along the propagation direction of acoustic wave). The acoustic field transmitted through the object is composited from a field presenting Fourier transformation of the hole shape and field, transmitted through the metal components in the longitudinal section of the object. A computer Fourier transformation of the digital data of the amplitude fields transmitted through the object components is performed instead of converging lens. The Fourier series of the object obtained as digital data after the transformation is multiplied with a term, describing the angle distribution of the field on spatial frequencies. The reconstruction of the image of the metal components is performed by reverse transformation, i.e. summing up in all spatial frequencies. 3D visualization of the transmitted through the hole acoustic field determines the hole geometry (circular, square, rectangular). It is shown that at the transmission of a short acoustic pulse through the components with different thicknesses and holes, presenting Fourier and non-Fourier transformation can be registered separately in contrast to the optics. PMID:17395232
High-resolution retinal imaging using adaptive optics and Fourier-domain optical coherence tomography
Olivier, Scot S.; Werner, John S.; Zawadzki, Robert J.; Laut, Sophie P.; Jones, Steven M.
This invention permits retinal images to be acquired at high speed and with unprecedented resolution in three dimensions (4.times.4.times.6 .mu.m). The instrument achieves high lateral resolution by using adaptive optics to correct optical aberrations of the human eye in real time. High axial resolution and high speed are made possible by the use of Fourier-domain optical coherence tomography. Using this system, we have demonstrated the ability to image microscopic blood vessels and the cone photoreceptor mosaic.
Spectral calibration for infrared hyperspectral imaging Fourier transform spectrometer based on absorption peaks
NASA Astrophysics Data System (ADS)
Li, YaSheng; Chen, Yan; Liao, Ningfang; Lyu, Hang; He, Shufang; Wan, Lifang
A new calibration method for infrared hyperspectral imaging Fourier transform spectrometer is presented. Two kinds of common materials as Polypropylene (PP) and Polyethylene Terephthalate (PET) films which have special absorption peaks in the infrared band were used in the calibration experiment. As the wavelengths at the sharp absorption peaks of the films are known, an infrared imaging spectrometer can be calibrated on spectra with two or three peaks. With high precision and stability, this method simplifies the calibration work. It is especially appropriate for the measuring condition with a lack of calibration equipment or with inconvenience to calibrate the multiple light sources outdoors.
Automated turbulences jitters correction with a dual ports imaging Fourier-transform spectrometer
NASA Astrophysics Data System (ADS)
Prel, Florent; Lantagne, Stéphane; Moreau, Louis; Roy, Claude
When the scene observed by an imaging Fourier-Transform Spectrometer is not stable in amplitude or in position during the time it takes to acquire to spectrum, spectro-radiometric artifacts are generated. These artifacts reduce the radiometric accuracy and may also damage the spectral line shape. The displacements of the scene in the field of view can be due to air turbulence, platform jitters or scene jitters. We describe an automated correction process based on the information provided by the second output port of a two-port imaging FTS. Corrected and uncorrected data will be compared.
Research on algorithm for infrared hyperspectral imaging Fourier transform spectrometer technology
NASA Astrophysics Data System (ADS)
Wan, Lifang; Chen, Yan; Liao, Ningfang; Lv, Hang; He, Shufang; Li, Yasheng
This paper reported the algorithm for Infrared Hyperspectral Imaging Radiometric Spectrometer Technology. Six different apodization functions are been used and compared, and the phase corrected technologies of Forman is researched and improved, fast fourier transform(FFT)is been used in this paper instead of the linear convolution to reduce the quantity of computation.The interferograms is achieved by the Infrared Hyperspectral Imaging Radiometric Spectrometer which are corrected and rebuilded by the improved algorithm, this algorithm reduce the noise and accelerate the computing speed with the higher accuracy of spectrometers.
Application of short-coherence lensless Fourier-transform digital holography in imaging through diffusive medium
NASA Astrophysics Data System (ADS)
Zhang, Yizhuo; Situ, Guohai; Pedrini, Giancarlo; Wang, Dayong; Javidi, Bahram; Osten, Wolfgang
We propose a short-coherence lensless Fourier-transform digital holography for imaging through scattering media. The technique utilizes a low-power cw diode laser with short temporal coherence and enables the selection of the early-arriving photons through a diffusive medium by interfering with a spherical reference beam from the same source. An averaging technique is introduced to extract the weak signal from strong background noise. The proposed technique is verified using both theoretical analysis and experimental demonstration by imaging an object through a 3-mm-thick chicken breast tissue.
Sampling reconstruction of N-dimensional bandlimited images after multilinear filtering in fractional Fourier domain
NASA Astrophysics Data System (ADS)
Wei, Deyun; Li, Yuanmin
This paper addresses the problem of multidimensional signal reconstruction from generalized samples in fractional Fourier domain including the deterministic case and the stochastic case. The generalized sampling expansion is investigated for the case where the fractional bandlimited input depends on N real variable, i.e., f(t)=f(t1,⋯,tN) and is used as a common input to a parallel bank of m independent N dimensional linear fractional Fourier filters Hα,k(u), k=1,⋯,m. For the deterministic input, the input is assumed to have its N dimensional fractional Fourier transform bandlimited to the frequency rang |ui|≤Ωi, for i=1,⋯,N. If m, the number of fractional Fourier filters, is written as a product of positive integers in the form m=m1m2⋯mN, and if the fractional bandlimited input f(t) is processed by fractional Fourier filter Hα,k(u)resulting m outputs gk(t), then f(t) can be reconstructed in terms of the samples gk(nT), each output being sampled at the identical rates of Ω1 csc α/m1π, Ω2 csc α/m2π,⋯, ΩN csc α/mNπ samples/second in t1,⋯,tN respectively. This contrasts with the rates of Ω1 csc α/π, Ω2 csc α/π,⋯, ΩN csc α/π in t1,⋯,tN needed for reconstruction of the unfiltered input f(t). Input sampling expansions in terms of samples of the output filters are given for both deterministic and stochastic inputs, the generalized sampling expansion for random input having the same form as for the deterministic case but interpreted in the mean-square sense. Our formulation and results are general and include derivative sampling and periodic nonuniform sampling in the fractional Fourier domain for multidimensional signals as special case. Finally, the potensional application of the multidimensional generalized sampling is presented to show the advantage of the theory. Especially, the application of multidimensional generalized sampling in the context of the image scaling about image super-resolution is
Mapping agroecological zones and time lag in vegetation growth by means of Fourier analysis of time series of NDVI images
NASA Technical Reports Server (NTRS)
Menenti, M.; Azzali, S.; Verhoef, W.; Van Swol, R.
Examples are presented of applications of a fast Fourier transform algorithm to analyze time series of images of Normalized Difference Vegetation Index values. The results obtained for a case study on Zambia indicated that differences in vegetation development among map units of an existing agroclimatic map were not significant, while reliable differences were observed among the map units obtained using the Fourier analysis.
Fourier synthesis image reconstruction by use of one-dimensional position-sensitive detectors.
Kotoku, Jun'ichi; Makishima, Kazuo; Okada, Yuu; Negoro, Hitoshi; Terada, Yukikatsu; Kaneda, Hidehiro; Oda, Minoru
An improvement of Fourier synthesis optics for hard x-ray imaging is described, and the basic performance of the new optics is confirmed through numerical simulations. The original concept of the Fourier synthesis imager utilizes nonposition-sensitive hard x-ray detectors coupled to individual bigrid modulation collimators. The improved concept employs a one-dimensional position-sensitive detector (such as a CdTe strip detector) instead of the second grid layer of each bigrid modulation collimator. This improves the imaging performance in several respects over the original design. One performance improvement is a two-fold increase in the average transmission, from 1/4 to 1/2. The second merit is that both the sine and cosine components can be derived from a single grid-detector module, and hence the number of imaging modules can be halved. Furthermore, it provides information along the depth direction simultaneously. This in turn enables a three-dimensional imaging hard x-ray microscope for medical diagnostics, incorporating radioactive tracers. A conceptual design of such a microscope is presented, designed to provide a field of view of 4 mm and a spatial resolution of 400 microm. PMID:12856730
Ultrasonic reflection imaging has the potential to produce higher image resolution than transmission tomography, but imaging resolution and quality still need to be further improved for early cancer detection and diagnosis. We present an ultrasound reflection image reconstruction method using the split-step Fourier propagator. It is based on recursive inward continuation of ultrasonic wavefields in the frequency-space and frequency-wavenumber domains. The inward continuation within each extrapolation interval consists of two steps. In the first step, a phase-shift term is applied to the data in the frequency-wavenumber domain for propagation in a reference medium. The second step consists of applying another phase-shift term to data in the frequency-space domain to approximately compensate for ultrasonic scattering effects of heterogeneities within the breast. We use synthetic ultrasound pulse-echo data recorded around a ring for heterogeneous, computer-generated numerical breast phantoms to study the imaging capability of the method. The phantoms are derived from an experimental breast phantom and a sound-speed tomography image of an in-vivo ultrasound breast data collected usi ng a ring array. The heterogeneous sound-speed models used for pulse-echo imaging are obtained using a computationally efficient, first-arrival-time (time-of-flight) transmission tomography method. Our studies demonstrate that reflection image reconstruction using the split-step Fourier propagator with heterogeneous sound-speed models significantly improves image quality and resolution. We also numerically verify the spatial sampling criterion of wavefields for a ring transducer array.
Field experiment performance of the receiver elements for a Fourier telescopy imaging system
NASA Astrophysics Data System (ADS)
Mathis, J.; Stapp, J.; Cuellar, E. L.; Cooper, J.; Morris, A.; Fairchild, P.; Hult, Dane; Koski, Katrina; Ramzel, Lee; Thornton, Marcia A.
Fourier telescopy (FT) is an active imaging technique that is a candidate for high resolution imaging systems which can be used to obtain satellite images out to geosynchronous target ranges. Fourier telescopy uses multiple beams that illuminate the target with a fringe pattern that sweeps across it due to a set frequency difference between beams. In this way the target spatial frequency components are encoded in the temporal signal that is reflected from the target. The FT receiver can then be composed of a large area "light bucket" collector, since only the integrated temporal signal is necessary to reconstruct the target image. The GEO Light Imaging National Testbed (GLINT) system was previously designed to obtain satellite images at geosynchronous ranges by using this technique. The "light bucket" receiver was designed use forty heliostats, each having a collection area of ten meters square, and composed of a 16 x 16 grid of two foot square mirrors. The heliostats would redirect the return light from the target onto a large spherical concentrator array composed of hexagonal mirror segments. This concentrator would then focus the return light onto a photomultiplier tube (PMT) detector. The FT Field experiment presented in this paper uses one 10-meter square heliostat and a single PMT, plus a scaled down secondary array to provide the optical elements of the receiver for the FT field experiment. In this paper, we will describe the performance characteristics of the heliostat, secondary, and PMT detector. Performance characteristics include optical wavefront, alignment, and alignment stability of the optical elements. Finally, results will be presented after the receiver was integrated with a transmitter system that provided the modulated FT signal from various targets. Image reconstructions will show that even using low quality "Light bucket" receiver optics and a 1.5 km horizontal path through the atmosphere, the modulated signal can still produce good image
Superresolution imaging method using phase-shifting digital lensless Fourier holography.
Granero, Luis; Micó, Vicente; Zalevsky, Zeev; García, Javier
A method which is useful for obtaining superresolved imaging in a digital lensless Fourier holographic configuration is presented. By placing a diffraction grating between the input object and the CCD recording device, additional high-order spatial-frequency content of the object spectrum is directed towards the CCD. Unlike other similar methods, the recovery of the different band pass images is performed by inserting a reference beam in on-axis mode and using phase-shifting method. This strategy provides advantages concerning the usage of the whole frequency plane as imaging plane. Thus, the method is no longer limited by the zero order term and the twin image. Finally, the whole process results in a synthetic aperture generation that expands up the system cutoff frequency and yields a superresolution effect. Experimental results validate our concepts for a resolution improvement factor of 3. PMID:19687979
Automated segmentation of intramacular layers in Fourier domain optical coherence tomography structural images from normal subjects
Zhang, Xusheng; Yousefi, Siavash; An, Lin
Abstract. Segmentation of optical coherence tomography (OCT) cross-sectional structural images is important for assisting ophthalmologists in clinical decision making in terms of both diagnosis and treatment. We present an automatic approach for segmenting intramacular layers in Fourier domain optical coherence tomography (FD-OCT) images using a searching strategy based on locally weighted gradient extrema, coupled with an error-removing technique based on statistical error estimation. A two-step denoising preprocess in different directions is also employed to suppress random speckle noise while preserving the layer boundary as intact as possible. The algorithms are tested on the FD-OCT volume images obtained from four normal subjects, which successfully identify the boundaries of seven physiological layers, consistent with the results based on manual determination of macular OCT images. PMID:22559689
In-vivo human corneal nerve imaging using Fourier-domain OCT
NASA Astrophysics Data System (ADS)
Shin, Jun Geun; Lee, Byeong Ha; Eom, Tae Joong; Hwang, Ho Sik
We have imaged human corneal nerve bundles by using real-time Fourier-domain OCT (FD-OCT). Corneal nerves contribute to the maintenance of healthy ocular surface owing to their trophic influences on the corneal epithelium. The FD-OCT system was based on a swept laser of a 50 kHz sweeping rate and 1.31 μm center wavelength. At the area including sclera, limbus, and cornea, we could successfully get the in-vivo tomograms of the corneal nerve bundles. The scan range was 5 x 5mm. In this study, the A-scan images in each B-scan were realigned to have a flat air-surface boundary in the final B-scan image. With this effort, we could align corneal nerve bundle in a same depth and get the 3D image showing the branched and threadlike corneal nerve bundles.
Color image encryption using iterative phase retrieve process in quaternion Fourier transform domain
NASA Astrophysics Data System (ADS)
Sui, Liansheng; Duan, Kuaikuai
A single-channel color image encryption method is proposed based on iterative phase iterative process in quaternion Fourier transform domain. First, three components of the plain color image is confused respectively by using cat map. Second, the confused components are combined into a pure quaternion image, which is encode to the phase only function by using an iterative phase retrieval process. Finally, the phase only function is encrypted into the gray scale ciphertext with stationary white noise distribution based on the chaotic diffusion, which has camouflage property to some extent. The corresponding plain color image can be recovered from the ciphertext only with correct keys in the decryption process. Simulation results verify the feasibility and effectiveness of the proposed method.
Field experiment and image reconstruction using a Fourier telescopy imaging system over a 600-m-long horizontal path.
Yu, Shu-Hai; Dong, Lei; Liu, Xin-Yue; Lin, Xu-Dong; Megn, Hao-Ran; Zhong, Xing
To confirm the effect of uplink atmospheric turbulence on Fourier telescopy (FT), we designed a system for far-field imaging, utilizing a T-type laser transmitting configuration with commercially available hardware, except for a green imaging laser. The horizontal light transmission distance for both uplink and downlink was ∼300 m. For both the transmitting and received beams, the height upon the ground was below 1 m. The imaging laser's pointing accuracy was ∼9.3 μrad. A novel image reconstruction approach was proposed, yielding significantly improved quality and Strehl ratio of reconstructed images. From the reconstruction result, we observed that the tip/tilt aberration is tolerated by the FT system even for Changchun's atmospheric coherence length parameter (r0) below 3 cm. The resolution of the reconstructed images was ∼0.615 μrad. PMID:27556991
Three-wave mixing with whispering-gallery modes for electro-optic modulation and photonic reception
NASA Technical Reports Server (NTRS)
Ilchenko, V. S.; Savchenkov, A. A.; Matsko, A. B.; Maleki, L.
We demonstrate an electro-optic microwave modulator with milliWatt control power and a sub-microWatt photonic receiver based on triply-resonant three-wave mixing in high-Q toroidal lithium niobate cavities with whispering-gallery (WG) modes.
Coupled-cavity electro-optically {ital Q}-switched Nd:YVO{sub 4} microchip lasers
Zayhowski, J.J.; Dill, C. III
Nd:YVO{sub 4} microchip lasers have been electro-optically {ital Q} switched to produce 12-{mu}J pulses of 115-ps duration at repetition rates of up to 1 kHz. At a repetition rate of 2.25 MHz, 0.16-{mu}J pulses with an 8.8-ns duration were obtained.
Electro-optical characteristics of ZrO2 nanoparticle doped liquid crystal on ion-beam irradiated polyimide layer.
Park, Hong-Gyu; Kim, Hyung-Jun; Kim, Myoung-Seong; Lee, Il-Hwan; Seo, Dae-Shik
It is well known that doping liquid crystals (LCs) with nanoparticles can readily change the physical and electro-optical properties of LC mixture. In this paper, we report on how the electro-optical properties and thermal stability of an LC system were enhanced by dispersing zirconia (ZrO2) nanoparticles in nematic LCs on ion-beam irradiated polyimide layers. Homogeneous LC alignment was achieved and ZrO2/LC mixture was applied in twisted-nematic (TN) mode. The addition of ZrO2 nanoparticles contributed to improvement of electro-optical properties in the TN LC cell by lowering voltage operation and decreasing response time. The TN LC cells with a ZrO2 nanoparticle concentration of 2.0 wt% showed the lowest threshold voltage of 2.0 V and the fastest response time of 15.3 ms. This enhanced electro-optical performance was likely due to van-der waals interactions and the screening effect of the ZrO2 nanoparticles in the LC medium. The thermal stability of the ZrO2/LC mixture was also improved compared to a pristine LC system. PMID:22966615