Two-channel self-focusing matched filter

Abstract

A two-channel self-focusing matched filter produced by a computer generated hologram is proposed in this paper. The filter function is synthesized for two different objects to be recognized. The composite filter function consists of two terms, one of which is formed by adding a negative quadratic phase factor into the conjugate Fourier spectrum of one object, and another, which is adding a positive quadratic phase factor into the Fourier spectrum of another object. The composite function is then encoded into a computer-generated hologram to fabricate a matched filter. When performing pattern recognition, the filter will produce two correlation signals of two objects in the first positive order and the first negative order of diffraction, respectively. The diffracted light can be self-focused in the plane at a designed distance behind the filter. The optical experiments have shown the capability of the filter for simultaneously recognizing two different objects.