Soft decision decoding for holographic memories with intrapage intensity variations

A holographic memory system using a two-dimensional array of code sequences and soft decision decoding is implemented. The random error correction and burst error correction capability of this system is shown. We can obtain l ower bit error rates using soft decision Viterbi decoding rather than using hard decision decoding or simple thresholding. Different threshold levels for each data pixel position are determined by considering intrapage intens ity variations. With these threshold levels, much lower bit error rates are obtained. The experimental results are presented.