Holographic implementation of complex filters with phase-only pixelated spatial light modulators

摘要

We discuss the performance of the double-phase holographic encoding of complex modulation, implemented with a phase-only spatial light modulator (SLM). A macro-pixel formed with two phase-modulated pixels of the SLM is required to encode each sampled value of the desired complex modulation. This complex modulation is obtained in the zero order term of the Fourier series associated to the macro-pixel structure. We discuss the performance of this holographic method with explicit consideration to the pixelated structure of the SLM. We show that an exact copy of the desired complex function, only attenuated by the SLM fill factor, is generated by the holographic code (with some additional high order off-axis terms). We derive a formula for the signal field reconstruction efficiency. This formula shows that the efficiency is dependent on the absorption (or modulus) of the encoded complex modulation. As an application, we show that the holographic code can be adapted (with slight modifications) to implement a highly isotropic edge enhancement filter.