推扫式线阵TDI CCD扫描调制传递函数分析

Scanning modulation transfer function analysis of push-broom linear TDI CCD

根据线阵TDI CCD离散采样的特点,以采样间距内成像调制度均值为基础,构建了推扫成像模式下线阵TDI CCD扫描方向的调制传递函数。该调制传递函数的数值分析表明:对于像元为10μm的线阵TDI CCD,行转移驱动时钟相数为4,3或2时,Nyquist频率处调制传递函数值分别为0.363,0.333或0.255;行频误差为1%及3%时,不同积分级数下调制传递函数变化曲线表明,增大行频误差及增加积分级数将使调制传递函数值减小,图像分辨率降低。成像实验结果符合所构建调制传递函数的定量分析结论。

Scanning modulation transfer function（MTF） for linear time-delay integration（TDI） charge coupled device（CCD） using push-broom imaging mode was established.The MTF which took the discrete sampling characteristics of linear TDI CCD into account,was based on the imaging modulation mean within sampling interval.The numerical analysis of the proposed MTF indicated that the value of MTF at Nyquist frequency for linear TDI CCD with 10 μm pixel size was 0.363,0.333 and 0.255 respectively,when the number of row transfer phase clocks was 4,3 and 2.When the row frequency error was 1% or 3%,the changes of MTF curves with different integration numbers implied that increasing the row frequency error and the integration number could decrease the value of MTF and reduce the image resolution.The results of imaging experiment agree with the quantity analysis of the proposed MTF.