A coherent optical correlator and matched filter maker

Experimental work with a compact, coherent, real-time optical correlator and a matched-filter-maker system is described. Attributes of the correlator include small size, the ability to correlate an input image with multiple references, and operation over a wide range of input light levels. The input scene enters the correlator by a system of lenses while the matched filters are prerecorded on a photographic plate that is inserted into the correlator. The correlator contains a miniature CCD (charge-coupled device) television camera upon which the correlations are projected. The output of the camera is a standard composite video signal that can be displayed on a simple monitor. A match between the input scene and one of the stored filters is indicated by the appearance of a bright correlation spot on the output monitor. Experimental results obtained with the system are given. It is found that correlator alignment drift with changes in temperature is a problem