Noise reduction of page-oriented data storage by inverse filtering during recording

Two novel techniques for eliminating deterministic noise from a age-oriented memory are presented. The first technique equalizes the output response of ON pixels by adjustment of the exposure of each pixel during the recording of each data page. A test image transmitted through the system measures the spatial nonuniformities, and the appropriate inverse filter is imposed upon the data page and recorded in the storage material. On readout, the output signal values are then spatially uniform, perturbed only by random noise sources. Experimental results of using this predistortion technique in a pixel-matched holographic storage system are shown. Under conditions of high volumetric density, raw bit-error-rate (BER) improvements of 6-8 orders of magnitude are obtained (from 10(-4) to <10(-10)). holographic storage to subtract from bright OFF pixels. contrast, BER improvements of 6 orders of magnitude (from 10(-2) to 10(-8)) are demonstrated. The second technique uses a phase shift during Under conditions of low spatial light modulator (C) 1998 Optical Society of America.