Measuring refractive index and optical homogeneity of crystal with Mach-Zehnder interferometer

A method of measuring refractive index of transparent media plate with Mach-Zehnder interferometer was introduced. Its formula was given, measurement error and precision were analyzed. The temperature differential was measured and the measurement precision was analyzed. The method was suitable to transparent media (solid or liquid). The practicability of the method was proved by measuring extraordinary refractive index of pure LiNbO₃ crystal plate, and it is shown that the method is used for measuring high refractive index of anisotropic crystal plate especially.