Measuring spatial coherence by using a lateral shearing interferometry.

A modified lateral shearing interferometry is proposed to measure the spatial coherence of partially coherent light beams. This interferometry based on a 4f system consists of a diffraction grating and a spatial light modulator (SLM). In this system, the diffraction grating splits the partially coherent wave into two copied waves, forming a shearing interferogram on the observation plane. The period of the composite blazing grating generated by the phase-modulated SLM is flexibly tuned for controlling the lateral displacement of the two copied waves. The complex degree of spatial coherence of the partially coherent field is obtained through measurements and Fourier analysis of the fringe pattern.