EFFECTS OF MULTILEVEL PHASE MASKS ON INTERPIXEL CROSS-TALK IN DIGITALHOLOGRAPHIC STORAGE

We study the interpixel cross talk introduced to digital holographic d ata storage by use of a multilevel phase mask at the data-input plane. We evaluate numerically the intensity distribution at the output dete ctor for Fourier plane hologram storage in a limited-aperture storage medium. Only the effect at an output pixel of interpixel cross talk fr om the four horizontal and vertical neighboring pixels is considered, permitting systematic evaluation of all possibilities. For random two- level and pseudorandom six-level phase masks, the influence of the pix el fill factor, as well as the aperture size of the storage medium, is studied. Our simulations show that, for a given aperture size, a rand om two-level mask is more susceptible to interpixel cross talk than is a pseudorandom six-level mask. Decreasing the pixel fill factor below 94% with a pseudorandom six-level phase mask makes it theoretically p ossible to have a system with no errors from interpixel cross talk if one particular 5-pixel pattern is forbidden through modulation coding. Reducing the input fill factor below 85% means that no patterns need to be excluded. (C) 1997 Optical Society of America.