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摘要:
受航天器体积和重量限制，航天星载遥感探测系统难以兼顾大口径、高分辨率以及高光谱信息同步获取的需求。针对这一问题，本文提出一种新型的高光谱成像系统，采用主次镜共用、多通道分离同轴五反光路设计，结合Offner凸面光栅光谱仪分光技术，实现从可见到长波红外的高光谱探测。该系统主镜口径为
1000 mm，在500 km轨高下，可见和短波、中波、长波、全色波段空间分辨率分别优于2 m、3 m、6 m和1 m。且系统全视场可达到2.3°，满足20 km幅宽的探测要求。为提高系统的像差与畸变校正能力，设计中引入高阶非球面，形成像方远心光路，实现了望远镜与光谱仪的光瞳匹配。此外，本文还将光谱仪模块整体放入冷箱制冷，从源头上抑制光机结构背景辐射对成像质量的影响。最终设计结果表明，该系统成像质量优良、布局简单且体积轻便，而且能够实现全谱段高光谱信息的同步获取，可广泛应用于星载对地探测成像等领域。Abstract:Due to spacecraft’s volume and weight constraints, it is challenging to simultaneously obtain large aperture, high resolution, and hyperspectral information in spaceborne remote sensing systems. We propose a novel hyperspectral imaging system that utilizes a shared primary and secondary mirror design and a coaxial five-mirror optical path for multi-channel separation. By integrating Offner convex grating spectroscopy, the system enables hyperspectral detection from the visible to the long-wave infrared spectrum. Design results indicate that with a primary mirror diameter of
1000 mm at an altitude of 500 km, the spatial resolution in the visible and short-wave bands exceeds 2 m, in the mid-wave band exceeds 3 m, in the long-wave band exceeds 6 m, and the panchromatic resolution is better than 1 m. The system achieves a full field of view of 2.3°, accommodating a swath width of 20 km for detection. To enhance the system's aberration and distortion correction capabilities, high-order aspheric elements are incorporated to create a telecentric optical path, ensuring optimal matching between the telescope and the spectrometer. Furthermore, we propose housing the spectrometer module in a cooling chamber to effectively mitigate the impact of background radiation from the optical structure on image quality. The final design demonstrates excellent imaging quality, a simple layout, and a compact structure, enabling the simultaneous acquisition of high spectral information across the entire spectrum. This system has broad applications in satellite-based earth observation and imaging.-
Key words:
- spaceborne /
- hyperspectral /
- full-spectrum /
- convex grating spectrometer /
- background radiation
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图 6 望远镜系统各谱段MTF图。(a) VNIR；(b) SWIR；(c) MWIR；(d) LWIR
Figure 6. MTF diagram of each spectral band. (a) VNIR; (b) SWIR; (c) MWIR; (d) LWIR
图 7 光谱仪拼接方案。(a)可见光光谱仪；(b)短波光谱仪；(c)中波光谱仪；(d)长波光谱仪
Figure 7. Splicing scheme of the spectrometer. (a) VNIR splicing; (b) SWIR splicing; (c) MWIR splicing; (d) LWIR splicing
图 9 全系统各波段调制传递函数图。(a) 全色；(b)可见；(c)短波；(d)中波；(e)长波
Figure 9. MTF diagram of each spectral band. (a) PAN; (b) VNIR; (c) SWIR; (d) MWIR; (e) LWIR
图 10 (a) 3.0~5.0 μm和(b) 8.0~12.5 μm黑体辐射出射度
Figure 10. Medium and long wave blackbody radiant exitance. (a) 3.0-5.0 μm; (b) 8.0-12.5 μm
图 11 中继系统与冷光阑匹配结构图
Figure 11. Matching structure diagram of relay system and cold stop
图 12 光谱仪低温光学结构示意图
Figure 12. Schematic of low temperature structure of the spectrograph
图 14 制冷温度对背景辐射的影响。(a)中波背景辐射；(b)长波背景辐射
Figure 14. Effect of temperature inwall on background radiation. (a) Medium wave background radiation; (b) long wave background radiation
表 1 光学系统的主要技术指标
Table 1. Key technical specifications of the optical system
类别 波段
/μm像元
尺寸
/μm焦距
/mmF数 空间
分辨率
/m幅宽
/km视场
角
/(°)像元数 全色 0.4-0.8 7.5 3750 3.75 1 20000 可见 0.4-0.9 15.0 3750 3.75 2 10000 短波 0.9-2.5 15.0 3750 3.75 2 20 2.3 10000 中波 3.5-5.0 15.0 2500 2.50 3 6667 长波 8.0-12.5 30.0 2500 2.50 6 3334 
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表 2 各谱段光谱仪参数
Table 2. Structural parameters of Offner spectrometer in each spectral band
类别 可见 短波 中波 长波 光谱分辨率/nm 10 20 40 80 波段数 50 80 37 56 像元尺寸/μm 15 15 15 30 光谱色散/mm 0.75 1.20 0.56 1.68 探测器规模 2048×256 2048×256 2048×256 1024 ×256光谱仪数量 5 5 4 4 狭缝/mm 30×5 30×5 25×4 25×4 相对孔径 0.13 0.13 0.20 0.20
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表 3 光谱仪公差设置
Table 3. Tolerance setting for spectrometer
类别 反射镜M1 光栅 反射镜M2 曲率半径/mm ±0.01 ±0.01 ±0.01 厚度/mm ±0.01 ±0.005 ±0.01 XY偏心/mm ±0.01 - ±0.01 XY倾斜/° ±0.005 - ±0.005 S+A不规则度/光圈 ±0.5 - ±0.5
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