给出了一种全新的膜系设计方法，该方法与目前常用的偏振分束器PBS分光镜所采用的多组膜堆周期膜系的设计方法有着本质上的区别。全新的PBS膜系的设计引入一种有序对偶递变方法，它是基于周期性有序地变换成递变非周期性设计，目的是扰动针对45°入射布鲁斯特角的敏感。采用了两种折射率材料光学厚度的递变，在SF75系列玻璃棱镜内部入射光能满足45°角±(5°～6°)变化、P偏振态的透射率平均不低于70%、S偏振态的反射率不高于99.6%的光学特征指标，而且偏振截止带的带宽可以扩展到400 nm～700 nm。简化了工艺难度，大幅度缩减镀膜时间，降低了投影显示器件制造成本，并提高了光学特征指标。

A new optical multilayer design for 45° incidence angle on PBS mirror is introduced. Compared with the traditional method of three stocks periodic multilayer design on PBS mirror, the new method is different in basic principles, which is called as non-periodic gradient multilayer method. It is based on the concept of changing the layers from period to non-period orderly. The purpose is to influence Brewster angle sensitivity effect on PBS mirror. Only two kinds of coating metrical were used on the substrate of SF75 prism glass deposition multilayer. P-polarization transition was over 70% and S-polarization reflection was less than 0.4% when incidence angle changed from 39° gradually to 51°. The bandwidth of the polarization cutoff was expanded to 400 nm~700 nm. The new design for LCOS display system improves optical performance, simplifies process and reduces coating time and production cost.