Research On The Calibration Technique Of The TDI CCD Remote Sensing Camera

With the development of secondary planet and application technique of the remote sensing, high-speed, high-quality, high-resolution remote sensor is required. The TDI CCD sensor has been demonstrated to be well suited for that purpose. the TDI CCD sensors have fine resolution,high sensitivity and low noise and satisfy the requirement of glimmer and light weight and soundly reliability for aerospace. The dissertation is put forward during the manufacture the TDI CCD remote sensing camera. The manufacture of the TDI CCD remote sensing camera is a complex project. It concerns many aspects and every aspect will decide the victory and fail of the whole project. The calibration of the TDI CCD imaging system is absolutely necessarily part of the manufacture the TDI CCD camera. In fact, the idea of the calibration is not only used in the visible light and infrared light. The calibration is needed in many measurement and exploration process. The essential of the calibration accurately is confirming the relationship of the measurement values and the physical quantity. This dissertation is followed the project of manufacturing the TDI CCD remote sensing camera, which is made by Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Science. The principle of the TDI CCD remote sensing camera is given and the advantage of the TDI CCD is discussed. The radiometric calibration, the system gain and response non-uniformity of the TDI CCD remote sensing camera are discussed. The radiometric calibration of the TDI CCD remote sensing camera is done in the emphases laboratory of application Optics. The integration sphere is used for simulating different radiance, which is decided by the different sun vertex angle and different reflectivity of the ground. The parameters of the gain and stage of the TDI CCD remote sensing camera are given through the analyzing of outcome of the experiment. The outcomes are used in the practice and the errors are discussed in the end of the experiments. The gain of the CCD camera is the conversion between the number of electrons recorded by the CCD and the number of the digital units (counts) contained in the CCD image. It is useful to know this conversion for evaluating the performance of the CCD camera. In this dissertation, the mathematical theory is given behind the gain calculation and shows how the mathematics suggests ways to measure the gain accurately. In this dissertation the gains were computed using the mean-variance method, also known as the method of photon transfer curves. This derivation uses the concepts of signal and noise and photon noise obeys the laws of Poissonian statistics. The results and figures of the system gain of the TDI CCD camera are given. In the aspects of non-uniformity correction of the system response, the reasons, which cause the non-uniformity, are discussed. Several methods of non-uniformity correction of the system are discussed. Based on photoelectric response of the individual pixel is linear, it is possible to correct the pixel non-uniformity by two-step. Firstly the single TDI CCD chip is corrected and later the four TDI CCD chips. The standard deviation of the four image chips after the correction is 6.46 times less than before correction.