Compensation for pixel misregistration in volume holographic data storage

We describe what we believe to be a novel postprocessing algorithm for comp ensating for misregistrations between a detector array and the coherent ima ge of a pixelated two-dimensional data page. A lookup table of baseline loc al offsets is combined with the dynamically measured global offset of the r eceived data page, producing an estimate of the total lateral shift of each small block of pixels. A serial algorithm then reallocates the appropriate portion of the signal detected by each pixel to its neighbors, accounting for both the linear and the quadratic contributions introduced by coherent illumination of square-law detectors. This procedure can relax the tight co nstraints on page registration, optical distortion, and material shrinkage that currently hamper page-oriented holographic storage systems. Experiment al results from a pixel-matched 1-Mpixel volume holographic system are pres ented, showing an increase in position tolerance (for a raw bit-en or rate <10(-3)) from <plus/minus>16% to +/- 40% of the pixel pitch. (C) 2001 Optic al Society of America.