The Characteristic of the Diffraction of a Grating under Spherical Lightwave Illumination

Based on the Fourier optics theory,the diffraction characteristic of a grating through a lens under spherical lightwave illumination is analysed.The analytical equation of the diffraction of the grating is given.The image plane of the sphere lightwave is just the diffraction fringe plane of the grating.Both the diffracton equation and the missing order equation of the grating are put forward.If the distance between the grating and the lens is shorter than the focal length of the lens,the distance of the adjacent diffraction light fringes is longer than that of the grating under planar lightwave illumination for the same focal length of the lens.