Patent ID: 6026053
Filing Date: 2000-02-15
Classification: G11C

Abstract:
A photorefractive read-only optical memory apparatus using phase, frequency, and angular modulation, comprising:a controllable quasi-monochromatic light source for producing collimated light;at least one photorefractive data layer deployed orthogonally to the direction of propagation of the collimated light of said controllable quasi-monochromatic light source and arranged such that the collimated light is transmitted through said photorefractive data layer and further comprising:at least one page area for storing recorded information and altering the transmitted collimated light, further comprising:at least one data page containing an array of phase altering storage pixels for encoding the recorded information as a phase delay of the transmitted collimated light, wherein said array of phase altering storage pixels are aligned, with respect to the transmitted collimated light, with all of said arrays of phase altering storage pixels in the same one of said page areas and with all of said arrays of phase altering storage pixels in any of said page areas aligned, with respect to the transmitted collimated light, with the same one of said page areas, and further wherein all of the phase altering storage pixels in any of said array of phase altering storage pixels in any of said data pages are carrier modulated in frequency and angle such that the carrier frequency and angle is unique for each data page amongst all the data pages aligned, with respect to the transmitted collimated light;a lenslet for each of said alignment of page areas for accepting the transmitted collimated light after passing through said alignment of page areas and transmitting transformed images of each one of said data pages, in accordance with the unique carrier frequency and angle modulation of said contained array of phase altering storage pixels, onto a spatial frequency plane;a transform plane shutter array, deployed in the spatial frequency plane, comprising a plurality of shutter elements for selectively passing the transmitted transformed image of only one of said data pages and not transmitting the unmodulated carrier transform;a reimaging lens for accepting the passed transmitted transformed image of only one of said data pages and imaging the passed transmitted transformed image of only one of said data pages onto an image plane;a photodetector array deployed in the image plane to receive the transmitted transformed image of only one of said data pages and reproduce the recorded data;means for controlling said transform plane shutter array to selectively chose one of said data pages; andmeans for accepting the reproduced data from said photodetector array.