Optical Associative Processors With Controlled Nonlinearity In The Fourier Domain

Abstract

Two types of optical associative memory for two-dimensional image retrieval using nonlinear correlation is described. The product between the input image and the stored images is obtained by nonlinear correlation technique which has a superior performance compared with the conventional optical correlation techniques in the areas of the light efficiency, the correlation peak to sidelobe ratio and correlation spot size. We show that for some noisy inputs, it is necessary to use nonlinearity at the Fourier plane to improve the correlation SNR. Using this technique, better quality images can be reconstructed and the need for optical gain and the optical feedback may be eliminated.