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1 November 1991Computer-aided photorefractive pattern recognition
A hybrid pattern recognition system which consists of photorefractive crystal, SLM, and computers is designed and analyzed. In this system, photorefractive crystals are used as dynamic real-time recording materials and optical coherent spatial filters. The problems of excessive sensitivity to scale and rotation in general optical matched filters are solved by computer-aided digital pre-processing. The limitation of angular deviation apart from the Bragg condition due to volume hologram leads to no shift invariant. Thus, the optical properties such as hologram recording speed and diffraction efficiency of FWM in photorefractive crystals are different and strongly depended on the operation condition. We design the most suitable architectures to fit the purpose of the system. Finally, the performance of the whole system is discussed.
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Ching-Cherng Sun, Ming-Wen Chang, Smile Yeh, Nai-Jen Cheng, "Computer-aided photorefractive pattern recognition," Proc. SPIE 1564, Optical Information Processing Systems and Architectures III, (1 November 1991); https://doi.org/10.1117/12.49710