全帧CCD相机时间延迟积分模式下的图像缺损

Image defect of full-frame CCD in TDI mode

长焦距面阵CCD相机以TDI模式进行动态横向多幅扫描成像时,行转移频率高或者曝光时间长会使图像输出有明显缺损,从而影响图像的判读。为解决这一问题,分析了全帧CCD相机TDI模式的工作原理,分析认为快门曝光过程中CCD存在的无效TDI转移是导致输出图像出现缺损的主要原因。通过实验验证了分析结果,并提出保证CCD曝光过程中TDI转移与机械快门曝光精确同步的方法来消除无效TDI转移。据此设计了光电同步定位法进行曝光控制,并研制了相应的快门光电同步装置。成像实验结果显示,该方法可将图像缺陷区域控制在15列像元内,解决了面阵CCD在TDI模式下输出图像的缺损问题,提高了图像判读精度。

When a long focal area-array CCD camera takes photos in a TDI mode for dynamic lateral multi-frame imaging,it will output images with large size defect on the edge of image because of the high line transfer frequency or long exposure time and will influence image interpretation.To overcome the problems,the operating principle of area-array CCD in the TDI mode was analyzed,and the analysis indicates that the large size defect in the image comes from the invalid TDI transfer stages of the CCD during shutter exposure process.The obtained results were verified by a experiment and a method that the TDI transfer was finished simultaneously with shutter exposure was proposed to remove the invalid TDI transfer.On the basis of the analysis,a photo-electricity positioning synchronized was proposed and a photo electricity synchronizer was developed to settle the headache.The results show that the image defect area is less than 15 column-pixels,which successfully solves the image defect from the area-array CCD camera in the TDI mode and improves its image interpretation accuracy.