折/衍混合多光谱红外成像光谱仪离轴系统设计

采用二元光学透镜作为分光元件的多光谱成像光谱仪,由于焦距随波长的变化改变了系统的F数,因此改变了系统的放大率,从而引起光谱图像的像元配准误差。为改进基于二元光学透镜的多光谱成像光谱仪的性能,首次提出将离轴三反射镜系统与具有二元光学透镜的变焦距系统相结合的新技术方案。设计了由三片二次非球面生成的无中心遮拦的前置望远镜,该望远镜不仅有利于提高多光谱成像光谱仪的集光能力,且有利于系统的小型轻量化。同时设计了含二元光学透镜的三片型变焦距组件,用来消除多光谱成像光谱仪的像元配准误差。整个多光谱成像光谱仪系统仅有6个单片,非常简单。另外,该系统在空间频率为20 c/mm时MTF超过0.3,充分满足红外焦平面探测器对多光谱成像系统分辨率的要求,像面尺寸为7.2 mm。适用于探测单元尺寸为25μm、规格为128×128元的红外焦平面探测器。

Design of hybrid refractive/diffractive off-axial optical system for multispectral infrared imaging spectrometer

The magnification changing with the incident wavelength, which would bring the different spectral image matching error, is inevitable in the multispectral infrared imaging spectrometer using binary optical element (BOE) as spectro"element because its focal length changes with incident wavelength. To improve the optical performance of the multispectral infrared imaging spectrometer, the hybrid refraction/ diffraction zoom optical system combining the off"axial three"mirror system is firstly put forward. The front element of multispectral infrared imaging spectrometer is an unobscured and afocal three "mirror telescope,which not only makes for enlarging the clear aperture of multispectral infrared imaging spectrome" ter,but also reduces the size and weight.The rear elements of multispectral infrared imaging spectrometeris a hybrid refractive/diffractive three#elements zoom optical system, which eliminates the different spec-tral image matching error in the multispectral infrared imaging spectrometer using BOE aThe magnification changing with the incident wavelength, which would bring the different spectral image matching error, is inevitable in the multispectral infrared imaging spectrometer using binary optical element (BOE) as spectro"element because its focal length changes with incident wavelength. To improve the optical performance of the multispectral infrared imaging spectrometer, the hybrid refraction/ diffraction zoom optical system combining the off"axial three"mirror system is firstly put forward. The front element of multispectral infrared imaging spectrometer is an unobscured and afocal three "mirror telescope,which not only makes for enlarging the clear aperture of multispectral infrared imaging spectrome" ter,but also reduces the size and weight.The rear elements of multispectral infrared imaging spectrometeris a hybrid refractive/diffractive three#elements zoom optical system, which eliminates the different spec-tral image matching error in the multispectral infrared imaging spectrometer using BOE as spectro element The designed system is very simple in structure. Moreover, the modulation transfer function (MTF) of the designed system is greater than 0.3 for 20 c/mm spatial frequency, which meets the resolution requirement of the stare array detector of the multispectral infrared imaging spectrometer. In addition, the image size of the designed system is 7.2 mm, which meets 25 μm detector cell and 128 ×128 infrared detector arrays.