文章从常见的折射率测定方法入手，分析了最小偏向角法和垂直入射法的误差灵敏度和合成不确定度，得出在相同顶角和偏向角的情况下最小偏向角法测量的不确定度约为垂直入射法1/2 的结论。同时，分析了折射率测定时光源带宽引起的色散对测量精度的影响，利用Herzberger 色散方程估计了ZnSe 的色散情况，获得了在5~10μm 波段的色散约为5×10-4 μm-1，从而确定了折射率测量的光源带宽需小于20 nm 的要求。本文从误差控制角度出发，对比了最小偏向角法和垂直入射法的精度，为我们红外材料低温折射率测量的下一步工作奠定了基础。

Based on common measurements of refraction, it is found that the precision of minimum deviation condition is better than that of vertical incidence condition according to our analysis of the sensitivity and uncertainty of them.Analysis shows that for the same deviation and apex angle, the uncertainty of the minimum deviation method is only 1/2 of the uncertainty of the vertical incidence method. Another factor which would also effects uncertainty is the bandwidth of optical source. From analyzing dispersion of ZnSe by Herzberger dispersion equation, it is found that the dispersion of ZnSe at the wavelength of 5~10 μm is approximately 5×10-4 μm-1. For a given accuracy, the optical source’s bandwidth is less than 20 nm.