提出一种棱镜耦合布儒斯特角双循环算法，实现了液体复折射率的精确测量.使用p线偏振光入射到等腰棱镜底面与待测液体样品的分界面上，逐步旋转棱镜，得到样品总光强反射率随入射角变化关系的实验曲线；基于菲涅尔公式及布儒斯特定律，分析了棱镜测量液体复折射率的基本原理，采取双循环拟合算法，求得样品折射率及消光系数；搭建了相应的实验系统，测量了印度墨水、脂肪乳溶液和二碘甲烷匹配液等样品的复折射率，也得到了印度墨水和脂肪乳溶液的折射率、消光系数随浓度变化的实验曲线.实验表明：测量液体折射率及消光系数的精度分别约为0.000 2和0.000 1，有较高的测量准确度及稳定性，测量液体折射率范围不受棱镜折射率限制.
Through the introduction of double-circulating measurement, the accurate measurement of complex refractive index of liquid was achieving by using the Brewster Angle measurement technology. The p polarized light went into interface of the bottom of an isosceles prism and sample to be measured . After rotating the prism step by step, the experimental curve of the relationship between the total light intensity reflectivity of the sample with the incident angle was made. Based on the Fresnel formula and Confucianism's specific law, the basic principle of the complex refractive index of liquid is analyzed, the refractive index and extinction coefficient of sample can be obtained by using binary fitting. Appling corresponding experiment system, the complex refractive index of the Indian ink, Fat Emulsion Injection and Diiodomethane refractive index matching liquid was measured and the samples experimental curve of the refractive index, absorption coefficient versus the concentration of liquid was composed. Experiment results showed that the measuring precision of liquid refractive index and the absorption coefficient were about 0.000 2 and 0.000 1 with high accuracy and stability. Meanwhile, the range of liquid refractive index is not limited by prismatic refractive index.