双层衍射光学元件能够在宽波段光谱范围内工作并具有较高的衍射效率。提出了工作在一定入射角范围内的双层衍射光学元件的复合带宽积分平均衍射效率的数学分析模型。设计了一种工作波段为0.4~0.9 m的含有双层衍射光学元件的宽波段光学系统。其焦距为28 mm, F/#为2, 视场达到18°。该系统采用Petzval物镜结构, 由四片透镜组成。在60 lp/mm处, 其调制传递函数(Modulation Transfer Function, MTF)大于0.67。所用双层衍射光学元件在0.4~0.9 m波段内的带宽积分平均衍射效率高于91%。系统中入射到衍射面上的角度为0°~8.62°。该双层衍射光学元件的复合带宽积分平均衍射效率为97.36%。与传统的折射式宽波段光学系统相比, 含有双层衍射光学元件的宽波段光学系统的结构更简单, 分辨率更高。

Double-layer diffractive optical elements (DOEs) can work within a wide spectral band and have high diffraction efficiency. A mathematical analytic model of the polychromatic bandwidth integration average diffraction efficiency for double-layer DOEs in a certain incident angle range is proposed. A 0.4 to 0.9 m wide waveband optical system containing double-layer DOEs is designed. The optical system has a focal length of 28 mm, a F/# of 2 and a field of view of 18°. It uses a Petzval objective structure consisting of four lenses. Its Modulation Transfer Function (MTF) is greater than 0.67 at 60 lp/mm. The bandwidth integration average diffraction efficiency of its double-layer DOEs is above 91% in the 0.4 to 0.9 m waveband. In the optical system, the incident angle upon the diffractive surface is within the range of 0° to 8.62°. The comprehensive bandwidth integration average diffraction efficiency of the double-layer DOEs is 97.36%. Compared with the traditional refractive wide waveband optical system, this wide waveband optical system containing double-layer DOEs has a simpler structure and higher resolution.