Coherent optical target recognition through a phase distorting medium

This paper presents a technique for distinguishing targets in a limited class, in case conventional imaging is unsuccessful due to a phase distorting medium closely overlaying the observation system. The procedure is to record the spatial density spectrum of a coherently illuminated object, construct its fourier transform, and then compare the resulting autocorrelation function with a limited number of possible autocorrelation functions. For a simple object, experimental results illustrate the effect that a close-lying phase distortion has on the conventional image as compared to that on the autocorrelation function.