共蒸法制备非均匀膜的速率控制分析

渐变折射率薄膜，又称为非均匀膜。利用德鲁德理论分析了混合介质膜的介电常量与各个膜料的介电常量之间的关系，介绍了共蒸法制备非均匀膜的制备机理。对混合膜的沉积速率为两种膜料的沉积速率之和的情况，分别从两种膜料的单分子体积是否相等和总的沉积速率是否为常数两个方面，探讨了双源共蒸法制备的非均匀膜的折射率分布规律与膜料的沉积速率之间的关系，并给出了几种常见的折射率分布如线性变化、正弦变化、指数变化和双曲变化规律的膜料沉积速率表达式。最后以混合介质膜的总沉积速率为常数、折射率按照线性变化为例进行了说明。

Graded index coatings are also called inhomogeneous coatings. Based on Drude theory, the relationship of dielectric constants between inhomogeneous coatings and coating materials was analyzed. The mechanism of preparing inhomogeneous coatings by multi-source co-evaporation was introduced. Subsequently, we discussed how to get the distribution of deposition rate v(x) of coating materials from the refractive index distribution n(x) of inhomogeneous coatings on the assumptions that the volumes of different materials were equal or not and the total deposition rate was constant or not, and some deposition rate expressions of different refractive index distribution such as linearity, sine, exponent, and hyperbola were given too. In the end, a simple example was given, in which the total deposition rate was constant and the change law of refractive index was linearity.