多层衍射元件的浮雕深度和基底材料的优化分析

在分析单层和多层衍射元件衍射效率的基础上，推导出光学系统中多层衍射元件浮雕深度和基底材料的一般关系式，并对这些变量进行优化，得到阿贝数的值大致在20～80之间，β的合理值在0.25～0.6之间，当2个衍射元件的阿贝数v1＜v2，且差值比较大时，阿贝数小的衍射元件的基底材料选择光学玻璃中的火石玻璃，阿贝数大的衍射元件的基底材料选择光学玻璃中的冕牌玻璃。根据这个方法，设计了3组可实现宽波段高衍射效率的不同材料、不同浮雕深度的组合，使得每组组合中两层衍射元件的衍射效率都在99%以上。

Optimized analysis of relief depth and substrate material of multi-layer diffractive elements

The common relational expression of the relief depth and substrate material of multi-layer diffractive elements in an optical system was derived on the basis of analyzing the diffractive efficiency of mono-layer and multi-layer diffractive elements, and the Abbe number of 20～80 and β=0.25～0.6 were obtained by the optimization of these variances. The optical system can achieve high diffractive efficiency in broad wave band by reasonably using multi-layer diffractive elements in optical system. The variances of the relief depth and substrate material of diffractive optical elements are considered in optical system design. The ways to choose the material and relief depth of diffractive elements are described. Three pairs of different material and relief depth elements which can realize the high diffractive efficiency in the broad wave band were designed with the method.