Experimental demonstration of the hybrid opto-electronic correlator for target recognition.

Optical target recognition using correlators is an important technique for fast verification and identification of images. The hybrid opto-electronic correlator (HOC) recently proposed by us bypasses the need for nonlinear materials such as photorefractive polymer films by using detectors instead, and the phase information is yet conserved by the interference of plane waves with the images. In this paper, we demonstrate experimentally the basic working principle of the HOC architecture using currently available technologies. For matched reference and query images, the output signal shows a sharp peak, indicating a match is found. For an unmatched case, a much lower peak value is observed, indicating no match. We also demonstrate the dependence of the output signal on the phases of the interfering plane waves and describe a technique using an interferometer and a servo for optimizing the output signal. As such, the work reported here paves the way for further development of the HOC for practical applications.