谐衍射中、长波红外超光谱成像系统设计

Design of hyper-spectral imaging system with harmonic diffraction element in medium and long infrareds

为了充分利用中波红外和长波红外的光谱信息，建立了谐衍射中、长波红外超光谱成像系统。利用谐衍射元件独特的色散特性，将谐衍射透镜应用于中、长波红外超光谱成像系统中，使系统在中波红外3．7～4．8μm和长波红外8．5～12μm的2个谐振波段内获取二百多个不同波长的图像信息。设计结果显示，在中波红外波段18lp／mm处，光学调制传递函数〉0．52；长波红外波段13lp／mm处，光学凋制传递函数〉0．51；光学系统的点斑均方根直径在中波红外波段小于279m，在长波红外波段小于34μm。得到的结果表明，光学调制传递函数在各个波长处均接近衍射极限，点斑的均方根直径完全可以与国内现有探测器的像元尺寸匹配。

By making the best of the spectral information of medium and long infrareds, a harmonic diffractive/refractive optical system in middle and long infrareds is established, the hyper-spectral imaging system has obtained more than 200 spectral images in medium-wave infrared band of 3.7-4.8 μm and long-wave infrared band of 8. 5-12 μm based on the special large dispersion capability of harmonic diffractive elements. The design results show that the optical modulation transfer function is greater than 0.52 at 18 lp/mm in medium-wave infrared band; and greater than 0.51 at 13 lp/mm in long-wave infrared band. Furthermore, the RMS spot diameter is less than 27 μm in medium-wave infrared band and is less than 34 μm in long-wave infrared band. Obtained data indicate that the optical modulation transfer functions at all wavelengths are close to the diffraction limit; and the RMS diameer of points can match with the pixel size of existing detectors.