PHASE-ANALYSIS OF DIFFRACTED BEAMS USING MULTIPLEXED FOURIER-TRANSFORM LENSES

The output from diffraction gratings is formed using a Fourier transform lens. Because optical detectors are sensitive to intensity, information about the phase of the diffracted beams is lost. The relative phase shift between different diffracted orders can be measured using a multiplexed lens consisting of two offset lenses This lens forms two separate copies of the diffraction pattern. If a diffracted order from one copy overlaps a different order from the second copy, the resulting interference allows analysis of the relative phase between the different diffracted orders. Experimental results are presented using multiplexed lenses written onto a magneto-optic spatial light modulator.