DUAL NONLINEAR CORRELATOR BASED ON COMPUTER-CONTROLLED JOINT TRANSFORM PROCESSOR - DIGITAL ANALYSIS AND OPTICAL RESULTS

The hybrid optoelectronic processor, presented in this paper, realizes the dual nonlinear correlation (DNC) in a set-up based on a two-step nonlinear joint transform correlator architecture. In the first step t hree power spectrum distributions (input scene power spectrum, referen ce target power spectrum, and the joint power spectrum) necessary for the nonlinear processing are captured with a CCD camera. Nonlinear mod ification of the joint power spectrum, which does not have to be symme trical in the input and reference channels, is introduced digitally. I n the second step, the modified joint power spectrum is Fourier transf ormed optically. Numerical analysis of this processor shows a crucial influence of the dynamic range and the limited number of grey levels o f the CCD camera during image acquisition in the first step, on the ou tput signal parameters and the discrimination capability of the set-up . Optical results of recognition obtained for noise-free segmented inp ut scenes show that the set-up enables the realization of various corr elation operations as CR-IF, POF, IF, PPC, etc. without any filters an d that the discrimination capability is easy to control by a proper se lection of the type of nonlinear processing.