Virtual Grating Shift Phase Moire Fringe On The Interferogram Processing And Application

The virtual grating phase-shifting moire fringe method is based on virtual grating technology, phase-shifting interferometry and moire technology. When a carrier interferogram is processed by this method, the effects of phase shifting can be attained without the phase shifting errors. Moire fringe patterns are formed by the superposition of the interferogram to be evaluated and the phase shifting virtual gratings generated by computer. Four phase shifting interferograms can be gained by filtering the four moire fringe patterns, then the phase of the interferogram to be evaluated is gained by the phase shifting interferometric algorithm.In this paper, the theory about the virtual grating phase-shifting moire fringe method is introduced and analyzed, the program for the method is designed; the filter methods both in spatial field and in frequency field are discussed, the results are compared each other and the parameters of two type filters are chosen .The errors of the algorithm are discussed and the effects of the interferogram expansion are analyzed. The feasibility of the virtual grating phase-shifting moire fringe method is achieved by comparing the results with those of ZYGO's. Some valuable applications are studied. Experiments are carried out and the results are presented.