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摘要:
针对航天星载遥感探测系统,由于航天器体积和重量限制,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。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。设计结果表明:该系统主镜口径
1000 mm,在500 km轨高下,可见和短波波段空间分辨率优于2 m,中波优于3 m,长波优于6 m,全色优于1 m。且系统全视场达到2.3°,满足20 km幅宽探测。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,实现望远镜与光谱仪的光瞳匹配。此外,本文还提出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,能够实现全谱段高光谱信息同步获取,可广泛应用于星载对地探测成像等领域。Abstract:Due to the constraints of volume and weight in spacecraft, it is challenging to simultaneously obtain large aperture, high resolution and hyperspectral information in satellite remote sensing systems. This paper proposes a novel hyperspectral imaging system that utilizes a shared primary and secondary mirror design, along with 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 exceed 2 m, in the mid-wave band exceed 3 m, in the long-wave band exceed 6m, 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 capabilities for aberration and distortion correction, 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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表 1 光学系统的主要系统技术指标
Table 1. Key technical specifications of the optical system
类别 全色 可见 短波 中波 长波 波段/μm 0.4-0.8 0.4-0.9 0.9-2.5 3.5-5.0 8.0-12.5 像元尺寸/μm 7.5 15.0 15.0 15.0 30.0 焦距/mm 3750 3750 3750 2500 2500 F数 3.75 3.75 3.75 2.50 2.50 空间分辨率/m 1 2 2 3 6 幅宽/km 20 视场角 /° 2.3 像元数 20000 10000 10000 6667 3334 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 表 3 各谱段光谱仪参数
Table 3. Structural parameters of Offner spectrometer in each spectral band
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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