为了更有效地增大光通过平行分束棱镜时产生的剪切差，以方便实验中光路的搭建，运用棱镜光扩束原理和菲涅耳公式对棱镜进行了优化设计，得到了一种新型的转向型复合式平行分束棱镜。经理论分析和举例论证，其在高透射比的基础上，很好地实现了增大剪切差的效果，并伴有光路转向的作用，具有较高的使用价值和实用性。

In order to increase the lateral shearing distance when light transit the parallel splitting prism,as well as facilitate the path building of rays in the experiment,the prism design was optimized based on the prism light scattering beam principle and Fresnel formula and a new kind of turning composite parallel splitting prism was obtained. Analytical and experimental results prove that the lateral shearing distance is extended accompanying with deflecting function if the prism is with high transmissivity,which is valuable and practical.