The Calibration Technology Of The TDI-CCD Camera On Lunar Exploration

In recent years, with the development of satellite remote sensing technology, higherrequirements for space remote sensors were proposed. The high-speed, high-quality,high-resolution space remote sensor had become the trend.The speed of the work wouldbe influenced in practice as improving the spatial resolution and the sensitivity. It was theTDI-CCD that the contradiction of the three factors was solved. And it could increase theresolution and the response uniformity. The ratio of signal to noise of the system and theF/#were also improved in any degree. So that it had a potential applications in the broadfield of space remote sensing, and would become the main technical means and the keytechnical measure of lightening the space remote sensor. TDI-CCD camera was thedirection of the space camera development. This paper was from the national lunarexploration research projects. TDI-CCD stereo camera was an important load on theguiding star in the second phase of lunar exploration research project, and had been usedto obtain more precise image of the lunar surface. It was the first time to make use ofTDI-CCD technology in China’s lunar exploration. In the text, the calibration techniqueof TDI-CCD camera in lunar exploration was mainly studied.Firstly, the working principle and the principle of laboratory calibration of theTDI-CCD remote camera were introduced in this paper. After that we reached apreliminary model of the system error to determine the relative radiometric calibrationprocess of the TDI-CCD experimental camera in lunar exploration. As well as thevarious factors infecting the image in the entire optical system were analyzed.Secondly, the response characteristics of TDI-CCD under different conditions of theintegration class, the gain and the line frequency were expatiated via data analysis. Theseconditions of the three factors were assembled to regulate the radiometric luminance.Then followed the calibration process, we made a further analysis, such as the treatment of the dark current, the relative calibration and absolute calibration. As the nonuniformitystill exists in the relative calibrated images, the results should be revised before absolutecalibration. During the process, we imitated the practical conditions as much as possibleto realize a variety of working conditions of the detector to complete the calibration.Again, according to the response characteristics of TDI-CCD, the calibration datawas optimized. Within the tolerance of error, a relative calibration matrix was obtained tobe suit for dealing with the data in any state of the camera, which solved the problem ofdiversity in the practical application process, and largely reduced the complexity ofpost-data processing.Finally, the optimal relative matrix and the corresponding relative matrix wererespectively verified by the data of extraventricular image. The maximum error and itscauses were analyzed. The results showed that the optimal matrix could take the place ofother calibration matrices to deal with data, in line with the project target. It greatlysimplified the work of processing the post-calibration data.