Analysis of the dual discrimination ability of the two-port photorefractive joint transform correlator

Applied Optics (Impact Factor: 1.78). 12/1995; 34(35):8154-66. DOI: 10.1364/AO.34.008154
Source: PubMed


An all-optical joint transform correlator featuring two operative correlation planes(ports) with complementary performance is presented. We present the theory of operation, derive the input-output characteristics, and demonstrate computer simulations and experimental results. The 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 performance of the two ports depends on an experimentally controlled beam intensity ratio and the photorefractive coupling coefficient. With appropriate selection of these parameters, the first port is capable of high discrimination, while simultaneously the second offers a low discrimination output. Our results show that the two-beam coupling port can achieve peak-to-noise and signal-to-noise ratio values better than the phase-only correlator, whereas the four-wave-mixing port performs similarly to the classical joint transform correlator. This leads to a potential application in which the correlator could be set up so that in one port a general class is detected (interclass) and, in the other, the specific item in a class is detected (intraclass).

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    ABSTRACT: We present what is to our knowledge the first quantitative analysis of the dual optimality that can be achieved in the all-optical two-port photorefractive joint-transform correlator. We determine the operating region where these ports have complementary performance: the first port performs well for non-Gaussian clutter noise, and the second port is optimal for additive Gaussian noise. Dual optimality is achieved without the performance compromise of the optimal trade-off filter approach. (C) 1995 Optical Society of America
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