大视场TDI CCD相机焦平面电路一致性设计
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摘要
针对大视场TDI CCD拼接相机焦平面存在各通道之间性能的差异性较大,导致多通道拼接好的图像存在明显的亮暗差别等问题,提出一种可靠的、有效的焦平面电路一致性设计方法。首先,介绍了TDI CCD拼接相机焦平面电路结构;其次,全面地阐述了影响焦平面电路非均匀性的因素;然后,从关键元器件筛选、关键电路及PCB一致性设计、FPGA软件一致性设计和多通道主时钟一致性设计四个方面进行了多通道焦平面电路的一致性设计;最后,经过实验证明,在饱和曝光量50%的辐照度下焦平面所有通道响应度的标准偏差为71.4,平均数码值的标准偏差为39.6,同时,所有通道中最低信噪比也能满足44.2dB,所有性能指标满足相机均匀性要求,实现了大视场TDI CCD相机全视场内的高质量成像。
The big performance difference of each channel of wide field focal plane circuit of TDI CCD camera will lead to problems in multi-channel stitching images such as apparent brightness difference.Thus in this paper,put forward is a kind of reliable and effective method of consistency for focal plane circuit design.Firstly,the structure of focal circuit of TDI CCD stitching camera is introduced.Secondly,comprehensively expounds the factors influencing the focal plane heterogeneity of the circuit.Then,from the four aspects such as key components selection,key circuit and PCB design,FPGA software consistency and multi-channel master clock consistency design were carried out to make the consistency design of the focal plane circuit.Finally,the experiments prove that under the saturation exposure irradiance of 50%,the standard deviation of all the channel responsivity and the average digital value is 71.4and 39.6,respectively.Meanwhile,the lowest SNR can reach 44.2dB,all the performance indicators meet the uniformity requirement of the camera,realizing high quality imaging in the full field of view for TDI CCD camera with big field of view.
The big performance difference of each channel of wide field focal plane circuit of TDI CCD camera will lead to problems in multi-channel stitching images such as apparent brightness difference.Thus in this paper,put forward is a kind of reliable and effective method of consistency for focal plane circuit design.Firstly,the structure of focal circuit of TDI CCD stitching camera is introduced.Secondly,comprehensively expounds the factors influencing the focal plane heterogeneity of the circuit.Then,from the four aspects such as key components selection,key circuit and PCB design,FPGA software consistency and multi-channel master clock consistency design were carried out to make the consistency design of the focal plane circuit.Finally,the experiments prove that under the saturation exposure irradiance of 50%,the standard deviation of all the channel responsivity and the average digital value is 71.4and 39.6,respectively.Meanwhile,the lowest SNR can reach 44.2dB,all the performance indicators meet the uniformity requirement of the camera,realizing high quality imaging in the full field of view for TDI CCD camera with big field of view.
引文
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[4]荣少巍.基于FPGA的高精度多通道采集存储系统研究[J].电子测量技术,2014,37(4):108-112.Rong Shaowei Research of FPGA-based high-precision multi-channel acquisition and storage system[J].Electron.Measurement Technol.,2014,37(4):108-112.
[5]李国宁,刘妍妍,张柯,等.高频差分采样技术在CCD信号处理中的实现[J].电子测量技术,2014,37(10):123-129.Li Guoning,Liu Yanyan,Zhang Ke,et al.High frequency difference of sampling technology in CCD signal processing[J].Electron.Measurement Technol.,2014,37(10):123-129.
[6]李益民,刘岩俊,何昕,等.高精度CCD拼接相机标定方法研究[J].半导体光电,2008,29(5):799-802.Li Yimin,Liu Yanjun,He Xi,et al.Research of calibration method for high-precision CCD butting camera[J].Semiconductor Optoelectronics,2008,29(5):799-802.
[7]王军,冯伟,刘金国,等.大视场多CCD拼接相机标定方法研究[J].光学与光电技术,2004,2(6):7-9.Wang Jun,Feng Wei,Liu Jinguo,et al.A calibration of multi-CCD ballistic camera with wide field of view and high precision[J].Opt.&Optoelectron.Technol.,2004,2(6):7-9.
[8]李洋,刘亚侠.TDICCD相机系统响应非均匀性校正[J].仪器仪表学报,2006,27(6):1226-1227.Li Yang,Liu Yaxia.Nonuniformity correction of system response based on the TDICCD camera[J].Chinese J.of Scientific Instrument,2006,27(6):1226-1227.