Simple technique for the determination of the complex transmittance of spatial light modulator

Abstract : We describe a simple technique for the determination of the complex transmittance of a spatial light modulator. The technique uses the variation of the diffraction efficiency of Ronchi gratings imprinted on the SLM, as a function of the grating contrast. The measurement is made on the central peak of the diffraction structure with a monopixel detector only. The technique can also be used in quasi real time in order to adjust the SLM in the expected working regime (phase only modulation for example)