Translation sensitivity adjustable compact optical correlator and its application for fingerprint recognition

A translation sensitivity adjustable compact optical correlator (TSACOC) utilizing a convergent reference wave has been designed and tested. Its properties and performances, including the location of the correlation peak and the effects of lateral and longitudinal displacements for both filters and input images, are systematically analyzed based on the nonparaxial approximation for the reference beam. The theoretical analyses have been verified in experiments. By discussing the practical problems encountered, we have found that the tolerance of the system to the input lateral displacement can be conveniently increased by changing a geometric factor of the system. This property is very important to a TSACOC with a pinhole aperture attached to an ordinary detector at a fixed place. In addition, the effectiveness of the TSACOC for fingerprint recognition is also presented. (C) 1996 Society of Photo-Optical Instrumentation Engineers.