TDI CCD成像电路系统响应模型的研究

Research on Response Model of TDI CCD Image System

为建立准确的时间延迟积分电荷耦合元件(TDI CCD)成像电路系统的响应模型,根据成像系统的信号处理流程,详细分析了CCD传感器、预放电路与视频处理电路等主要环节对系统响应的影响,并结合理论响应模型,针对实际的处理流程,建立了实际系统的理论响应模型。利用某航天相机TDI CCD成像系统进行了暗电流噪声、视频处理电路噪声等专项测试实验,并在不同的拍照参数与光辐射条件下进行了辐射定标实验,分析了具体的实验图像数据,采用最小二乘法的线性拟合与二次多项式拟合分别得到了系统响应的近似数学模型和高精度数学模型,拟合决定系数R2分别达到了0.992和0.9998。利用该响应模型可以准确计算卫星在轨拍照时地物的辐射特性,并为合理选择相机在轨拍照参数提供依据。成像实验表明,系统响应模型准确,参数设置合理,满足相机在轨拍照的任务要求,提高了相机在轨工作的效率。

To establish accurate response model of time delay integration charge coupled device （TDI CCD） image system, the main parts are analyzed in detail, such as CCD sensor, amplifier circuits and video processing circuit, according to the flow of signal processing. The response model for the actual system is established in theory based on the flow processing. The noises of dark current, video processing circuit are tested on a spatial TDI CCD image system. And so is the radiometric calibration under conditions of different parameters and illuminations. The image data of experiments is analyzed. An approximate formula and a precise formula are achieved by linear polynomial and quadratic polynomial of the least square method. The goodness of fit for linear and quadratic polynomial shows that R2 reaches 0. 992 and 0. 9998, respectively. The radiation character of ground targets can be acquired by the response model. And the choice of reasonable working parameter can also be decided according to the model. The experimental results show that the response model of image system is accurate and the working parameters are reasonable, which meets the demand and improves the efficiency of on-orbit spatial camera.