Spatial phase-shifting moire deflectometry

A novel spatial phase-shifting method is presented from the moire phenomena. With the analysis to moire patterns from the scalar diffraction theory, there is stable phase shift between different order diffraction interferograms of moire deflectometry. This phase shift just depends on the distance between two gratings and the grating period. In this spatial phase-shifting method, no beam splitter, polarizer or wave plate is used and the disadvantage of uncertain phase shifts due to the methods using polarizer or wave plate is removed.