研究了椭偏测量中多层薄膜拟和模型建立的过程，并对一未知多层光学薄膜进行了椭偏分析，建立了substrate/film1/EMA/film2/srough 的物理结构模型。采用椭偏法，在首先确定出基底光学常数的基础上，提出了从单层、双层、三层逐次建模拟和的分析方法。研究结果表明：对于透明或弱吸收光学薄膜，采用柯西公式可以较好表征材料的色散关系。椭偏分析最终得到的未知薄膜基本结构为G(1.52)/2.031 2(203.0 nm)1.463 6(170.1 nm) 2.079 1 (170.4 nm) /A，膜系设计及分光光度计测量的透射光谱证实了这一结果。对多层膜厚度和光学常数的分析表明，椭偏法仍然是一种行之有效的薄膜光学常数测量方法。

The fitting model of multi-layer thin films in ellipsometry analysis was established. An unknown film was investigated and the physical structure model of substrate/film1/EMA/film2/srough was applied. Based on spectroscopic ellipsometry after determining the optical constant of the substrate, the modeling method of increased layers from single to 3-layer was provided. The results indicate that the Cauchy dispersion model is available for optical transparent or weak-absorption thin films. The structure of the unknown film was fitted with a model of G (1.52)/2.031 2 (203.0 nm) 1.463 6 (170.1 nm) 2.079 1 (170.4 nm) /A by ellipsometry analysis method, and the result was confirmed by the transmission spectrum from a spectrophotometer. The analysis to optical constant and film thickness also show that the ellipsometry is effective for multi-layer thin films analysis.