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向双向偏理,提了一法测量玻璃双棱镜微小底角新方法,介绍了测量基本理,讨论了测量误差.