TDI-CMOS图像传感器多次采样叠加调制传输函数模型研究

Research on Modulation Transfer Function Model of TDI-CMOS Image Sensor with Oversample-Superposition

提出了多次采样叠加下时间延迟积分(TDI)CMOS图像传感器沿扫描方向的调制传输函数(MTF)分析模型。基于行滚筒曝光读出原理,研究了一个行时间内采样次数、叠加次数、TDI级数和速度失配比对扫描MTF的影响机理。为验证扫描MTF模型,基于TDI-CMOS图像传感器将连续视场映射为离散图像的几何和能量传输关系分析,建立了成像仿真系统并利用刃边法计算MTF曲线。仿真结果表明,扫描MTF随着采样次数增加而增大;当采样次数固定,扫描MTF随着叠加次数增大而减小;扫描MTF随着速度失配比和TDI累加级数增大而减小。

An analytical model of modulation transfer function （MTF） for time-delay-integration （TDI） CMOS image sensor with oversample-superposition in the scanning direction is proposed. Impacts of sample number in a line-time, superposition number, TDI stage and velocity mismatch ratio on scanning MTF are studied based on the along-track- rolling exposure readout principle. To verify the scanning MTF model, an imaging simulation system is established, which is based on analysis of geometric and energy transmission relationship from continuous scene to discrete image on the TDI-CMOS image sensor. Then knife-edge method is used to calculate the MTF curve. The simulation results show that scanning MTF increases with the increase of sample number, scanning MTF is negatively related to superposition number when sample number is fixed, and scanning MTF decreases with the increase of velocity mismatch ratio and number of TDI stages.