Abstract

A matched filter in the Fourier plane is a complex function consisting of phase and amplitude. This cannot be written on a spatial light modulator (SLM) in a real-time system. The phase-only filter obviates this problem in that only a phase function needs to be written. We show that a good autocorrelation comparable to a matched filter can be obtained using the exact phase of the reference function and an amplitude mask which is an ensemble average of a class of similar object. Only the phase portion is updated in a library search and can be implemented in real time on a binary phase-only SLM. The position of the amplitude mask is not critical and could be changed by mechanical means to search for different classes of object. Computer simulation results are presented for the average amplitude matched filter with both continuous and binary phase and compared to the standard matched filter.

© 1988 Optical Society of America