静止轨道星载差分吸收光谱仪CCD成像系统设计

静止轨道卫星差分吸收光谱仪采用摆扫成像方式对大气进行探测,针对其工作时CCD成像系统信噪比大于1 000、高速探测模式下探测周期小于10min、高分辨率模式下探测周期小于1h的要求,进行CCD成像系统设计.选取CCD47-20作为探测器,设计成像电路实现光谱图像信号的采集和上传.分析了帧叠加和像元合并对时间、空间分辨率的影响.结合帧转移CCD的特点设计了每个位置最后一帧读出时摆镜转动的成像方式,并合理设置了帧叠加数和像元合并数,达到优化成像周期的目的.1s曝光时间条件下,该CCD成像系统的高速、高分辨率模式探测周期分别为515s和3 315s,图像信噪比均大于1 000,污染物观测实验中未出现失帧或重复的现象.该CCD成像系统方案满足静止轨道星载差分吸收光谱仪的探测需求,为静止轨道环境监测仪器设计提供参考.

CCD Imaging System Design for Geostationary Satellite-borne Differential Optical Absorption Spectrometer

The geostationary satellite-borne differential optical absorption spectrometer detects the atmosphere by whiskbroom imaging.Aiming at the requirements of signal-to-noise ratio bigger than 1000 and the spectrometer's detection period of less than 10 min in high-speed detection mode and less than 1 h in high-resolution mode,the CCD imaging system was designed.Selecting CCD47-20 as the detector,the imaging circuit was designed to realize the sample and upload of image signal.The effects of frame co-added and binning on the time and spatial resolution were analyzed.Combined with the characteristics of the frame transfer CCD,the imaging method of swinging the mirror when reading the last frame of each position was designed,and the number of frame co-added and binning were set reasonably to achieve the purpose of optimizing the imaging cycle.Under 1s exposure time,the detection period is 515 s in high-speed mode and 3315 s in high-resolution mode,and the signal-to-noise ratio is greater than 1000 in both two modes.In the pollutant observation experiment,there is no missing frames or duplication occurred.The CCD imaging system meets the detection requirements of the geostationary spaceborne differential optical absorption spectrometer,and provides a technical reference for the design of a spectrometer imaging system eventually applied to a geostationary satellite.