Two-shot point-diffraction interferometer with an unknown phase shift

Abstract

On the basis of a modified Mach–Zehnder interferometer, this paperproposes a two-shot point-diffraction interferometer (PDI), by which twoπ-shifted interferograms are created according to the principle of half-wave loss and aresimultaneously captured by a single CCD camera. After an arbitrary unknown phase shiftis induced, a second and final shot captures these last two patterns. Then a novel algorithmbased on statistical principles is developed to extract the actual phase shift and thewavefront phase from four interferograms. The combination of two required shots and arobust algorithm allows the proposed PDI to be implemented efficiently and accurately.Related simulation and experiments are conducted to prove the correctness of the proposedmethod.