星载高分辨力近红外CO_2光谱仪设计

Design of Spaceborne High Resolution Near Infrared Imaging Spectrometer

为了测量大气层中分布在近红外波段（1 591~1 621 nm）的CO_2吸收光谱,设计了一种高分辨力光谱探测仪,并开展了相关原理样机的研制。对国外载荷进行分析,系统选用了平面反射光栅分光的结构形式。光谱仪由前置望远物镜及成像光谱仪组成,望远镜采用匹兹伐结构,以满足系统大相对口径、小瞬时视场的特点。通过ZEMAX进行仿真和优化设计,系统实现了0.1 nm的高光谱分辨力,在20 lp/mm处MTF大于0.65。这种方案工程实现性好,设计方法与结果合理可行。

In order to measure the absorption spectrum, whose radiation wavelength range is between 1 591 nm to 1 621 nm（near infrared band）,a kind of high spectral resolution spectral detector is designed for measuring the near infrared CO_2 absorption bands, and the instrument underlying is in progress. Compared with existing optical systems applied to spaceborne hyperspectral imagers abroad, a simple planar reflection grating structure is selected for beam splitting. The whole detector is consisted of a fore optics system and a spectral imaging system. To fit the big opposite aperture（F1.8） and small IFOV, Petzval construction is applied to the fore optics system. The system＇s simulation and optimization is completed by ZEMAX optical design software, which shows that the optical design completely and feasibly meet the application requirements. System realize the high spectral resolution of 0.1 nm, and the Modulation Transfer Function（MTF） of both the center and the edge wavelength are higher than 0.65 at the characteristic frequency of 20 lp/mm.