Tikhonravov Alexander V, Trubetskov Michael K, Amotchkina Tatiana V, Dobrowolski J A
Research Computing Center, Moscow State University, Leninskie Gory, 119992 Moscow, Russia.
Appl Opt. 2008 May 1;47(13):C124-30. doi: 10.1364/ao.47.00c124.
We deal with optimal two-material antireflection (AR) coatings for the visible and adjacent spectral regions. It has been shown before that, for a given set of input parameters (refractive indices of the substrate, ambient medium and high- and low-index coating materials, and for a given spectral width of the AR coating), such designs consist of one or more clusters of layers of approximately constant optical thickness and number of layers. We show that, through the analysis of many different optimal coatings, it is possible to derive two parameters for a simple empirical expression that relates the residual average reflectance in the AR region to the number of clusters. These parameters are given for all possible combinations of relative spectral bandwidth equal to 2, 3, and 4; low-index to ambient-medium index ratio equal to 1.38 and 1.45; and high-to-low index ratio equal to 1.4, 1.5, and 1.7. The agreement between the numerically and the empirically calculated values of residual average reflectance is excellent. From the information presented the optical thin-film designer can quickly calculate the required number of layers and the overall optical thickness of an AR coating having the desired achievable residual average reflectance.
我们研究适用于可见光及相邻光谱区域的最佳双材料抗反射（AR）涂层。之前已经表明，对于给定的一组输入参数（基底、环境介质以及高折射率和低折射率涂层材料的折射率，以及对于给定的AR涂层光谱宽度），此类设计由一层或多层具有近似恒定光学厚度和层数的层簇组成。我们表明，通过对许多不同的最佳涂层进行分析，可以为一个简单的经验表达式推导出两个参数，该表达式将AR区域中的残余平均反射率与层簇数量相关联。这些参数针对相对光谱带宽等于2、3和4；低折射率与环境介质折射率之比等于1.38和1.45；以及高折射率与低折射率之比等于1.4、1.5和1.7的所有可能组合给出。残余平均反射率的数值计算值与经验计算值之间的一致性非常好。根据所提供的信息，光学薄膜设计者可以快速计算出具有所需可实现残余平均反射率的AR涂层所需的层数和总光学厚度。
