自准直法测焦距中的假相与排除

The false appearance and It's Removal in the Determination of Focal Length by Self-collimation

假相是由折射球面∑＿１反射球面∑＿２、折射球面∑＿１构成的光学系统所成．实验中转动平面镜可以将二者分开．

The false appearance is formed in the aptical system which consists of a refraction spherical surface ∑_1,a refraction spherical surface ∑_2 and a refraction spherical surface ∑1;Rotating the plane mirror,the false appearance may be sorted out from the real one.