星载大气痕量气体差分吸收光谱仪前置光学系统设计

Design of Fore Optical System in Space-Borne Differential Optical Absorption Spectrometer for Atmospheric Trace Gas Monitoring

星载大气痕量气体差分吸收光谱仪通过获取地球大气或地表反射、散射的紫外/可见光辐射,监测大气痕量气体的全球分布。为实现大视场、紫外/可见光宽波段探测、高光谱分辨率和小型化等研制目标,设计了一种前置光学系统,具体由前置望远镜和中继光学系统构成。其中,前置望远镜通过两片偏轴球面镜实现在交轨方向114°视场的覆盖;中继光学系统则通过中继反射镜、分色片及中继镜头将探测光谱(240～710nm)分为4个光谱通道,并将各谱段的光分别导入各自光谱成像系统中进行探测。设计结果表明,前置光学系统在大视场范围内、在探测的紫外/可见光宽波段内均能具有良好的成像结果,为后续的光谱成像达到高光谱分辨率提供了保障。前置光学系统整体体积紧凑,重量轻,在无摆扫前提下,满足大视场需求以及适应星载等平台的搭载需求。

Space-borne differential optical absorption spectrometer is used for atmospheric trace gas distribution monitoring through acquiring high accuracy ultraviolet/visible （UV/VIS） radiation scattered or reflected by air or earth surface. To achieve the goals of large view angle, wide UV/VIS waveband detection, high spectral resolution and compact structure in space, a fore optical system is designed. It includes fore-optics telescope and relay optical system. To detect viewing field at 114° in cross-orbit direction, fore-optics telescope with two pieces of off-axis spherical mirrors is designed. Relay optical system consists of relay mirror, coloriseparation filters, and relay lens, which separates the incident light into four spectral channels covering 240~710 nm. Then we import each beam of light into corresponding spectral imaging channels respectively. The design result shows that the fore optical system works efficiently inside the field of view for both UV and VIS waveband, providing good imaging quality. That makes it possible to implement high spectral resolution of subsequent systems. The fore optical system has more compact structure and lighter weight comparing with other products. It can meet the requirement of spaceborne and airborne platforms without using a scan mirror.