Abstract: The transmittance characteristic of three-slabs whose configuration is glass-semitransparent liquid-glass was analyzed based on ray trace method，and transmittance ratio calculation model of semi-transparent liquid was developed.The unique value range and multi-value range of double-thickness model of thermal radiation physical property measurement of semi-transparent liquid with transmission method were discussed，and the application range of the inverse model was attained.The optical constants of heptane attained in the references were selected as the true values，and the spectral transmittance ratio of the semi-transparent liquid based on the direct model simulation were regarded as the experimental values.The optical constants of heptane were achieved by the inverse models.Good agreement was obtained between the retrieved optical constants of heptane and the experimental data attained in the references.Then the influences of measurement error on the inverse results were also investigated.

Key words: semi-transparent liquid, three-slab, thermal radiation physical property, complex refractive index, inverse model

摘要： 基于光线跟踪法研究了玻璃-半透明液体-玻璃三层平板透射特性，给出了获取夹层内液体透射比模型。分析了透射法测量液体热辐射物性的双厚度模型的单值性和多值性条件，给出了其适用范围。以庚烷热辐射物性测量为例，采用正问题模型计算透射比并作为“测量值”，利用双厚度模型反演n、k。结果表明，在一定n、k的范围内双厚度模型反演误差较小，且利用其反演庚烷的n、k与文献实验数据吻合较好，同时分析了测量误差对反演的影响。

关键词: 半透明液体, 三层平板, 热辐射物性, 复折射率, 反演模型