Patent ID: 6016210
Filing Date: 2000-01-18
Classification: G03H,G11B

Abstract:
A method for mitigating scatter noise in output patterns of hologram while reading out a hologram from a holographic storage medium, the hologram being written by interfering a write reference beam and an object beam, the method comprising the steps of:(a) illuminating the holographic storage medium with a first read reference beam propagating along a centerline of the write reference beam;(b) producing a first hologram output pattern from the holographic storage medium, the first hologram output pattern including a first data signal pattern and a first noise pattern;(c) recording the first hologram output pattern on a detector array having M rows of pixels, the recorded first hologram output pattern having a first signal-to-noise ratio;(d) transferring electric charges of pixels in each originating row of the M rows of pixels to corresponding pixels in a subsequent row of the M rows of pixels, the distance between an originating row and a subsequent row being equal to the translation distance between the first data signal pattern and the succeeding data signal pattern;(e) illuminating the holographic storage medium with a succeeding read reference beam, the succeeding read reference beam forming a separation angle with the first read reference beam;(f) producing a succeeding hologram output pattern from the holographic storage medium, the succeeding hologram output pattern including a succeeding data signal pattern and a succeeding noise pattern, the succeeding data signal pattern substantially corresponding to the first data signal pattern shifted by a translation distance related to the separation angle, the succeeding noise pattern being uncorrelated to the first noise pattern; and(g) recording the succeeding hologram output pattern on the detector array such that electric charges associated with the succeeding hologram output pattern are added to preexisting electric charges of pixels in the detector array, the recorded succeeding hologram output pattern having a signal-to-noise ratio substantially greater than the first signal-to-noise ratio.