Optical multiple pattern recognition with a correlator using a single binary phase-only filter

Simulated and experimental results are presented for a mutiplexed, frequenc y-plane, correlator that is capable of recognizing a plurality of input pat terns with a single, binary, phase-only, correlation filter. The correlator incorporates a pixellated, binary phase, random coded, fixed mask in the i nput plane that gives enhanced performance and, by introducing space-varian ce, enables the output to be presented in simple coded forms. The correlati on filter is designed using a standard optimization technique. As the numbe r of reference patterns stored in the filter is increased, performance is d egraded but can be at least partially regained by increasing the number of pixels in the mask and filter. Detailed results are given for a 128 x 128 p ixel, eight-character recogition correlator showing two forms of output cod ing. (C) 2000 Published by Elsevier Science B.V. All rights reserved.