TDI CMOS图像传感器曝光时间优化方法研究

Integration Time Optimization for TDI CMOS Image Senor

为了提高时间延迟积分互补金属氧化物半导体(TDI CMOS)图像传感器的成像质量,研究了TDI CMOS图像传感器中曝光时间的选取对成像质量的影响。基于行滚筒曝光读出原理,分别分析了曝光时间对信噪比(SNR)和调制传递函数(MTF)的影响机理,根据分析结果,提出在级数已选定的情况下,曝光时间的选取存在最优值,此时得到的图像质量较好。为验证结论,基于自主研发的TDI CMOS图像传感器芯片及现场可编程门阵列(FPGA)开发板,搭建了TDI CMOS图像传感器成像测试系统。实验中采用MTF×SNR作为评价图像质量的指标,实验结果表明,在选定的相机参数下,积分级数为8级,光强为20 lx时,TDI CMOS图像传感器曝光时间选取64 ms时所得到的图像质量最好,此时MTF×SNR最大。

In order to improve the image quality of the time delay integration complementary metal oxide semiconductor （TDI CMOS） image sensor, the influence of integration time selected on image quality is studied. Based on the rolling shutter readout principle, the impacts of integration time on signal to noise ratio （SNR） and modulation transfer function （MTF） are analyzed respectively. According to the results of the analysis, it is proposed that in the case of series selected ,the optimal value exists in the selection of integration time, which makes a better image quality. To validate the conclusion, on the basis of self-developed TDI CMOS image sensor chip and field programmable gate array （FPGA） development board, the imaging testing system of TDI CMOS image sensor is set up. By using MTF x SNR as the image quality evaluating index in the experiment, the experimental results show that under the selected camera parameters, the stage is 8, and the light intensity is 20 Ix, when the integration time is 64μs, the best image quality can be obtained and the MTFx SNR is maximum.