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Various nonlinear mapping techniques have been investigated for exploiting the restrictive characteristics of available spatial light modulators (e.g., phase-only or binary phase-only) and/or to modify the performance of coherent optical correlators. The phasewith- constrained-magnitude filter (PCMF) is a practical complex spatial filter realizable with today’s technology. It relies on the coupling between magnitude and phase transmittance exhibited by certain types of spatial light modulators. It requires relatively little computational effort to implement, and its performance has been shown to compare quite favorably with that of phase-only filters. In this paper we review the basic PCMF concept and show how performance of the PCMF can be improved by modifying the basic PCMF algorithm in two ways: (1) by setting the magnitude transmittance of the spatial light modulator to its lowest achievable value for a chosen set of low spatial frequency components and (2) by adjusting the values of the desired spatial frequency distribution relative to the available dynamic range of the spatial light modulator. The second method, in particular, can be used to make the PCMF perform more like an inverse filter or more like a matched filter, depending on the desired results.
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