Diffraction field of orthogonal cosine-gratings

In order to analyze diffraction field of orthogonal cosine-gratings,it was analyzed based on the method of wave-front phase factors and considering the influence of limited aperture of grating.The phase-front function,amplitude and intensity expressions of the diffraction field were deduced.The amplitude and intensity of light distribution diagram of phase plane were obtained.Finally,the half-angle-width of maximum value in the center was given.This study may further provide a theoretical foundation to analyze diffraction of orthogonal cosine-gratings.