IMPLEMENTATION OF A PHOTOREFRACTIVE BINARY JOINT TRANSFORM CORRELATOR

The use of photorefractive materials such as Bi12SiO20 as dynamic holo graphic media is becoming an interesting alternative to that of the cu rrent liquid-crystal-based modulators in real-time optical image proce ssing. We present an experimental realization of optical correlation f or pattern recognition by means of a photorefractive joint transform c orrelator. The correlator operates with a liquid-crystal television as the input and a photorefractive crystal at the recording plane. We co nsider two possible ways of registering the Fourier plane information: conventional detection of the joint power spectrum, and utilization o f only phase information at the Fourier plane by suitable preprocessin g of the scene and the reference at the object plane. We compare the l atter case with the performance of a binary joint transform correlator . Analysis, simulations, and experimental results are presented. (C) 1 998 Optical Society of America.