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SiO2薄膜是光学薄膜领域内常用的重要低折射率材料之一.在文中研究中,通过测量薄膜的椭偏参数,使用非线性最小二乘法反演计算获得薄膜的光学常数.采用离子束溅射和电子束蒸发两种方法制备了SiO2薄膜,在拟合过程中,基于L8(22)正交表设计了8组反演计算实验,以评价函数MSE为考核指标.实验结果表明:对IBS SiO2薄膜拟合MSE函数影响最大的为界面层模型,对EB SiO2薄膜拟合MSE函数影响最大的为Pore模型.同时确定了不同物理模型对拟合MSE函数的影响大小和反演计算过程模型选择的次序,按照确定的模型选择次序拟合,两种薄膜反演计算的MSE函数相对初始MSE可下降35％和38％,表明拟合过程模型选择合理物理意义明确.文中提供了一种判断薄膜物理模型中各因素对于薄膜光学常数分析作用大小的途径,对于薄膜光学常数分析具有指导意义.“,”SiO2 thin films were deposited by ion beam sputtering (IBS) and electron beam evaporation (EB) technologies.The optical constants of SiO2 thin films were fitted by nonlinear least square algorithm.8 group experiments were designed based on L8 (22) orthogonal array.The results show that intermix is the most important factor for the IBS SiO2 thin film while Proe model for the EB SiO2 thin film.The values of MSE evaluation function for IBS SiO2 thin film and EB SiO2 thin film decline 35％ and 38％ respectively,which shows that the physical models are reasonable and the physical meaning is clear.The method to estimate the effect of different factors was offered,which is meaningful for the analysis of optical constants of thin films.