Based on the double refraction principle of outgoing beam in the biprism,the displacement method for measuring the small angle of biprism is presented.The error of this method is also discussed.

利用双棱镜引起射光束方双的原理,提了一种位法量玻璃双棱镜微小底角的新方法,介绍了量的基本原理,讨论了量误差.