Space-variant processing using phase codes and Fourier-plane sampling techniques
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Any slowly varying linear space-variant system can, in principle, be represented holographically by spatially sampling the input plane and multiplexing the respective system transfer functions. A scheme reported earlier for implementing this technique makes use of phase diffusers in the reference beam paths to encode sequentially recorded holograms. However to minimize the cross talk between the holograms upon playback the diffusers should have good correlation properties, In this thesis extensive computer simulations to evaluate the correlation properties of a family of binary phase codes are conducted. An alternative multiplexing technique in which the transfer functions are sampled in the Fourier plane to generate a composite hologram is also described. In this technique the samples of the transfer functions are placed in non-overlapping regions and hence there will be no crosstalk upon playback. However multiple copies of the input function are required during the playback step. The results of preliminary experiments conducted to evaluate this approach for space-variant system representation are presented including the verification of coherent addition using computer multiplexed holograms.