Principle of defocusing scatter-plate interferometer based on statistical optics

Among the theories of scatter plate interferometer, the method based on statistical optics is most successful. This method is developed in this paper. The method of equivalent field based on fractional Fourier transform and the method of statistical average based on statistical optics are used. The relations between the interference fringes and the wave aberration of the tested lens are described, when the two scatter plates are not in the conjugal planes of tested lens.