HOLOGRAPHIC MEMORY WITH CORRELATOR BASED READOUT

The investigation of an inverted hybrid digital/optical VanderLugt typ e correlator based on a holographic memory is reported in this paper. A set of reference templates is stored in a photorefractive crystal (P RC) by angular hologram multiplexing. In the filter plane, a phase-mod ulating liquid crystal television (LCTV) serves as a phase-only input device. During the recognition process, which is based on the pure pha se correlation, the reference templates are correlated sequentially wi th the input object. This correlator shows high sensitivity to object rotation, sharp correlation peaks, high light efficiency, and is fully shift-invariant in spite of the PRC thickness. The influences of the LCTV on the performance of the system are discussed and experimental r esults are shown.