一种测量透明薄膜折射率的方法

用一个三棱镜把光耦合到被测量透明薄膜上；由另一个三棱镜把光耦合出来。当光束在与被测量薄膜的界面刚好发生全反射，由棱镜２耦合出的光突然消失。这时光束进入被测量薄膜的入射角为临界角。测出入射棱镜的入射角，从而求出该薄膜相对不论的临界角，由此而求出该透明薄膜的折射率。

A method of measurement refractive index of transparent films with double-prisms

With one prism couples a light beam onto a measured transparent film, another couples the light beam out. When the light beam is just at total reflection on the plane of the measured material, the light beam that is coupled out by prism 2 suddenly disappears. This incident angle of the measured material is the critical angle of material. The critical angle is calculated by measuring the incident angle of prism 1 and calculating the refractive index of the transparent material. This method is simple to be operated and the sample is easy to be fabricated. This method is not only used to measure the refractive indices of thin films, but also used to meaure light-guiding substrates, transparent liquieds and solids. The accuracy of this method is same as that of minmum deviation method.