CCD亚像元成像质量的调制传递函数分析

Analysis of CCD Subpixel Imaging Quality Based on Modulation Transfer Function

从调制传递函数MTF的定义出发,对CCD离散抽样过程的MTF进行分析,指出CCD器件的MTF不仅与输入信号的频率有关,而且与相位有关,得出了CCD器件的平均调制传递函数的计算公式。通过计算对CCD的一般成像、亚像元成像和互有四分之一像元位移的成像系统的调制传递函数进行分析比较,结果表明,理论上亚像元成像获得图像的分辨率能达到一般成像的两倍,互有四分之一像元位移的成像系统获得的图像分辨率能达到一般成像的3.74倍。在空间频率低于CCD的Nyquist频率时,多CCD的成像质量也明显好于一般成像质量。

The modulation transfer function(MTF) of discrete sampling process of CCD sensor is analyzed from the definition of MTF.The MTF of CCD sensor is not only related with the frequency of input signal,but also influenced by the phase.The calculating formula of average MTF of CCD sensor is acquired.After the comparison of the average MTF of general imaging,subpixel imaging and imaging system with a quarter of pixel displacement,this paper obtains the results that the resolution of the image acquired by subpixel imaging is theoretically about twice of the one acquired by general imaging,and the resolution of the image acquired by imaging system with a quarter of pixel displacement is about 3.74 times of the one acquired by general imaging.The results also show that the imaging quality with multiple CCD is obviously better than that of general imaging when the spatial frequency is lower than the Nyquist frequency of the CCD sensor.