PROGRAMMABLE IMAGE ASSOCIATIVE MEMORY USING AN OPTICAL DISK AND A PHOTOREFRACTIVE CRYSTAL

The optical disk is a computer-addressable binary storage medium with very high capacity. More than 1010 bits of information can be recorded on a 12-cm-diameter optical disk. The natural two-dimensional format of the data recorded on an optical disk makes this medium particularly attractive for the storage of images and holograms, while parallel ac cess provides a convenient mechanism through which such data may be re trieved. In this paper we discuss a closed-loop optical associative me mory based on the optical disk. This system incorporates image correla tion, using photorefractive media to compute the best association in a shift-invariant fashion. When presented with a partial or noisy versi on of one of the images stored on the optical disk, the optical system evolves to a stable state in which those stored images that best matc h the input are temporally locked in the loop.