从理论上计算了由于光束倾斜入射产生的棱镜起偏系统角谱宽度的压缩效应，计算结果表明，入射光束相对于棱镜入射面的入射角越大对角谱宽度的压缩就越明显，不同材料的基底折射率的差别对角谱宽度的压缩影响不大。通过举例从膜系设计的角度进一步论证了这一结论。还指明在实际系统中可以保持入射光束的相对角度不变的情况下，通过改变棱镜的形状来达到倾斜入射的目的从而实现角谱宽度的压缩。对如何设计出高性能的宽角宽光谱偏振分束镜具有重大的指导意义。

Compression effect of angular width for polarizing beam splitter under tilted incidence is caclulated. The calculated result shows that the larger the tilted angle is, the more distinct the compression effect, difference of substrate refractive index has little influence on the compression effect. The conclusion is testfied by the designing of thin fim coatings ulteriorly. In practical use when the direction of incident light is kept invariable the compression effect of angular acceptance width can be realized by changing the shape of the PBS prism. The result has a great help to design polarizing beam splitter with a wide augluar acceptance and spectrum bandwidth in practice.