ANALYSIS OF THE DUAL DISCRIMINATION ABILITY OF THE 2-PORT PHOTOREFRACTIVE JOINT TRANSFORM CORRELATOR

An all-optical joint transform correlator featuring two operative corr elation planes (ports) with complementary performance is presented. We present the theory of operation, derive the input-output characterist ics, and demonstrate computer simulations and experimental results. Th e two-port joint transform correlator is based on simultaneous use of two photorefractive wave-mixing architectures. The first port uses two -beam coupling, and the second port uses four-wave mixing. The perform ance of the two ports depends on an experimentally controlled beam int ensity ratio and the photorefractive coupling coefficient. With approp riate selection of these parameters, the first port is capable of high discrimination, while simultaneously the second offers a low discrimi nation output. Our results show that the two-beam coupling port can ac hieve peak-to-noise and signal-to-noise ratio values better than the p hase-only correlator, whereas the four-wave-mixing port performs simil arly to the classical joint transform correlator. This leads to a pote ntial application in which the correlator could be set up so that in o ne port a general class is detected (interclass) and, in the other, th e specific item in a class is detected (intraclass). (C) 1995 Optical Society of America