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摘要: 针对用于地球静止轨道卫星的遥感面阵快照式成像光谱仪传输数据量过大引起的数据传输困难、信号采集处理时间长的问题,利用地球静止轨道平台可以长期驻留固定区域上空的特点,提出采用压缩感知的大口径宽谱段快照式光谱仪方案,对其光学系统结构进行设计,并对相关参数进行了计算。物镜采用同轴三反式无焦系统,用分色片对系统分光,经过对各系统进行优化处理,最终获得了幅宽为400 km×400 km,可见光地面像元分辨率为50 m、中波红外地面像元分辨率为400 m、长波红外地面像元分辨率为625 m的光学系统。该设计中,可见光路在78.125 lp/mm的MTF高于0.455,中波红外的光谱分辨率为光路在33.3 lp/mm处的MTF高于0.518,长波红外光路在20.8 lp/mm处的MTF高于0.498;可见光光谱分辨率为20 nm、中波红外的光谱分辨率为50 nm、长波红外的光谱分辨率为150 nm;可见光路二级光谱小于0.05 mm,设计结果具有良好的成像质量,各部分光学系统成像质量接近衍射极限,设计结果满足应用和指标需求。Abstract: Due to the excessive data transmission of the geostationary orbit array staring spectrometer, the data transmission is difficulty and signal acquisition and processing time is long. According to the characteristic that geostationary orbit platform can stay over the fixed area for a long time, a scheme of large aperture visual and infrared snapshot spectrometer based on compressive sensing was proposed. The physical model of compressive sensing spectral imaging was analyzed, the structure of the optical system was designed, and the relevant parameters were calculated. A coaxial three-mirror afocal optical system was used in objective lens, and dichroic films were used to split the spectrum. After optimization, the optical system was shown with a width of 400 km×400 km, 50 m Ground Sample Distance (GSD) in visible part, 400 m GSD in Middle Wave Infrared (MWIR) part and 625 m GSD in Long Wave Infrared (LWIR) part. The results show that the MTF in the visible part is higher than 0.455 at 78.125 lp/mm, the MTF in mid-wave infrared region is higher than 0.518 at 33.3 lp/mm, and the MTF is higher than 0.498 at 20.8 lp/mm in long-wave infrared region. The spectral resolutions are 20 nm, 50 nm, and 150 nm in the visible part, the mid-wave infrared region, and the long-wave infrared region, respectively. The second-order spectrum of the visual part is less than 0.05 mm. The optical system has good imaging performance, and the imaging quality of each part of the optical system is close to the diffraction limit, which meets the needs of applications and indicators.
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表 1 光学系统设计要求
Table 1. Requirements for optical system design
可见光系统 中波红外系统 长波红外系统 空间分辨率/m 50 400 625 幅宽/km 400×400 400×400 320×320 光谱分辨率/nm 20 50 150 表 2 光学系统探测器参数
Table 2. Parameters of the optical system’s detector
可见光系统 中波红外系统 长波红外系统 像元数/pixel 8000×8000 1024×1024 512×512 像元尺寸/μm 6.4×6.4 15×15 24×24 表 3 光学系统最终设计参数
Table 3. Parameters of the designed optical system
可见光系统 中波红外系统 长波红外系统 系统孔径/mm 700 视场角2ω/(°) 0.66×0.66 0.66×0.66 0.52×0.52 系统焦距/mm 4500 1350 1375 表 4 子系统参数
Table 4. Parameters of the sub-optical system
可见光一次会聚
光路/准直光路中波红外一次会聚
光路/准直光路长波红外一次会聚
光路/准直光路系统焦距/
mm900/534 270/137 275/124 光栅线对数/
(lp·mm−1)170 50 45 -
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