基于多层衍射光学元件衍射效率的表达式, 推导出了双层衍射光学元件空气间隙与衍射效率的关系。分析了空气间隙、周期、入射波段对衍射光学元件在可见光波段、红外中波、红外长波衍射效率的影响。以[400~700 nm]、[3~5 μm]、[8~12 μm]波段为例, 分别以聚碳酸酯(PC)、聚甲基丙烯酸甲酯(PMMA)为可见光波段双层衍射光学元件第一、第二层的基底、以硫化锌(ZnS)和硒化锌(ZnSe)为红外中波和长波双层衍射光学元件第一、第二层基底材料。在特定周期情况下, 确定了双层衍射光学元件空气间隙的大小对多层衍射光学元件的衍射效率的影响。

Based on the expression of diffraction efficiency for multilayer diffractive optical element, the relationship between the air gap of a two-layer diffractive optical element and diffraction efficiency is derived. The influence on diffraction efficiency of the diffraction optical element in visible spectrum, infrared medium wave and infrared long wave from air gap, period and incident wave is analyzed. Taking 400~700 nm, 3~5 μm and 8~12 μm wavelength as examples, with polycarbonate (PC), poly methyl methacrylate (PMMA) as the first layer basement and the second layer basement of the two-layer diffraction optical element in visible wavelength respectively, with zinc sulfide (ZnS) and zinc selenide (ZnSe) as the first layer basement and the second layer basement of the two-layer diffraction optical element in infrared medium wave and infrared long wave. In particular period situation, the influence on diffraction efficiency of multilayer diffractive optical element from the size of air gap of two-layer diffraction optical element is determined.