Abstract

Adaptive photodetectors are based on the effect of non-steady-state photo-induced electromotive force. The effect consists in generation of an alternating (AC) electric current through a short-circuited photorefractive or photoconductive sample due to interaction of the instantaneous spatial distribution of photoconductivity produced by a vibrating light pattern with that of the stable diffusion-type space-charge electric field recorded by this or another light pattern. This field pattern recorded in the sample is efficiently reconstructed (i.e. produces the maximal output AC current) only under illumination by the matched (i.e. the same) light pattern that gives rise to the photoconductivity distribution. Any other (nonmatched) or shifted picture produces noncoherent signals from different areas of the device resulting in a weak noise-like output signal. Recently we suggested to use this property for correlation analysis of 2D patterns [1].

© 1996 IEEE