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Real-time numerical reconstruction of digitally recorded holograms

The numerical reconstruction of digitally recorded holograms has constituted the bottle neck for real-time digital holography. The reconstruction process can be understood as the diffraction that undergoes a wavefront as it illuminates the digitally recorded hologram. As this process is done numerically, the reconstruction of a M × N pixels hologram into an image of similar dimensions is an operation with a Ο (M × N)2 complexity. The diffraction process can be represented by a Fresnel transform or a scalable convolution of the recorded hologram. In these representations the numerical reconstruction has a complexity of Ο (M × log N)2, still quite demanding computationally if the holograms are of 2048 × 2048 pixels. In this work, the power provided by a Graphics Processing Unit (GPU) is used to accelerate the numerical reconstruction of digitally recorded holograms. The methodology is supported on the parallelization of typical Fresnel transform and scalable reconstruction algorithms. On reconstructing holograms of 2048 × 2048 pixels, the reconstruction is speeded up 20 times for the former method and 11 times for the scalable convolution. For holograms of 1024 × 1024, the accelerated reconstruction methods allow for real-time digital holography.