光波经过光学位移反射器后，由于全反射的存在，入射光的s偏振分量和p 偏振分量在相位上将产生一个额外的常量差值，这将导致出射光相对于入射光的偏振状态发生变化。通过分析高反膜的反射机理及其结构特征，同时结合直角棱镜的几何结构，提出了基于高反膜膜系结构的直角棱镜保偏膜设计方法，该方法通过将设计膜系镀制到直角棱镜的两直角面上，使光束经过直角棱镜平行反射后，偏振状态保持不变。同时，对该方法进行了可行性研究和误差分析。结果表明，该方法结合目前成熟的高反膜制作工艺，理论可行，易于实现商业化应用；对于光波的小角度入射误差而言，方案所述镀膜直角棱镜的保偏特性表现出良好的稳定性。

An extra constant difference between s and p component is produced after the light gets through the reflector based on total reflection,which lead to the change of the polarization state as a result. A novel design method of the polarization-preserving films for rectangular prism based on high-reflection films is proposed after deep analysis on its working mechanism and the geometry of the prism.The polarization state is kept invariant by plating the designed films on the two planes of the prism.The method has been theoretically and experimentally proved to be feasible.It is also easy to realize commercial application with the mature fabrication process of the high-reflection films. What′s more,the polarization-preserving characteristic of the method works well with little incidence error.