一束光通过屋脊棱镜，在镜内会被分为两条路径传播。两条路径偏振传输特性的差异，导致了零级衍射光斑的分裂现象，严重影响了光学系统的成像质量。为了弄清楚这种分裂现象，利用相干偏振理论，全面研究了不同偏振态的光束通过Schmidt棱镜后的光强分布。此光强分布同时包含了棱镜的结构参数。通过对此光强分布进行分析，得到了对准单色光的如下结论：1) 均匀态偏振光通过棱镜后的分裂双峰间距随着偏振度的增加而增加，且双峰极大值的光强差也随之增加；2) 矫正屋脊棱镜衍射光斑分裂现象的最理想条件为偏振矩阵因子B=0。通过改变单一界面入射角的方式获得不同偏振度的单色偏振光。检测该单色偏振光经过Schmidt棱镜后的衍射分布，得到与相干偏振统一理论分析一致的结果。

A laser beam can be split into two sub-beams when it passes through a roof prism. The difference of polarization transmission characteristics between the two paths leads to the splitting of the zero-order diffraction spot, which seriously affects the imaging quality of the optical system. In order to clarify this splitting phenomenon, the light intensity distribution of different polarization beams passing through a Schmidt prism is comprehensively studied by using the theory of coherent polarization. Through the analysis of the light intensity distribution, the following conclusions about the alignment of monochromatic light are obtained: 1) The distance between two splitting peaks after the uniform polarized light through the prism increases with the increase of the degree of polarization, and the light intensity difference of the maximum of two peaks also increases; 2) the most ideal conditions for correcting roof prism diffraction spot splitting phenomenon is the polarization matrix factor equal to 0. By changing the angle of incidence of a single interface, different degrees of polarization of monochromatic polarized lights are got. The diffraction distribution of the monochromatic polarized light passing through the Schmidt prism is measured and the results are consistent with the unified theoretical analysis of the coherent polarization.