为了在低照度下获得高的灵敏度和空间分辨率, 行间转移CCD相机能够按一定的方法以时延积分(TDI)方式工作。辐射定标实验中发现, 这种工作方式会造成某些像元的输出明显低于其他像元, 从而导致系统像元响应不均匀性和信噪比变差。提出了一种改进的TDI模式行间转移CCD相机辐射定标方法。该方法将TDI级数作为变量加入到像元响应不均匀性和信噪比的算法中, 在基本不影响正常使用的前提下大幅提高系统的性能。验证实验结果表明, 和原方法相比, 改进后的辐射定标方法能够有效降低系统的响应不均匀性并提高信噪比, 更加真实地反映系统特性。当采用32级TDI方式时, 像元响应非均匀性从4.88%降低至0.86%, 而信噪比提高了2.9%。

In order to obtain higher responsivity and spatial resolution under poor illumination condition, interline transfer CCD camera can be designed to work in time delay and integration (TDI) mode similar to TDI CCD. Whereas it is found that outputs of some pixels are obviously lower than others′ as interline transfer CCD camera works in TDI mode in laboratory radiometric calibration experiments. In result, photo response non-uniformity(PRNU) and signal noise ratio(SNR) of the system become worse. An improved radiometric calibration method of interline transfer CCD camera based on TDI working mode is put forward. In this method, TDI stage is taken into account in PRNU and SNR algorithms and system performance is improved remarkably with few influences on use. Results of validation experiments prove that the improved radiometric calibration method can efficiently improve SNR and lower PRNU of the system. In addition, characteristic of the system can be reflected better with the improved radiometric calibration method. As working in 32 TDI stages, PRUN is reduced from 4.88% to 0.86% and SNR is improved about 2.9%.