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Photoinduced anisotropy in pyrrlfulgide and its application in optical image processing and polarization holography

Photoinduced anisotropic properties of pyrrylfulgide are studied. From measurement of the photoinduced spectrum of dichroism, the birefringence spectrum is evaluated by Kramers-Kronig relations. At optimal exposure of 13 ~ 20J/cm2 a maximum photoinduced dichroism (Dperpendicular - Dparallel) of about 0.1 and a maximum photoinduced birefringence (nperpendicular - nparallel) of about 8×10-4 are achieved. We exploit this photoinduced anisotropy and use a pyrrylfulgide/PMMA film to demonstrate optical image processing such as contrast reversal, image subtraction and summation, low-pass filtering and edge-enhancement. From the spectra of dichroism and birefringence the spectrum of the diffraction efficiency for polarization holography is calculated. We demonstrate that diffracted images with high signal-to-noise-ratio (SNR) can be obtained by holographic recording with orthogonal polarization.