Study On Active Boresight Method For An Atmospheric Lidar System Based On CCD Imaging

Lidar technology is one of the most useful and important method to monitor the atmosphere, which can detect aerosol, clouds, water vapor, temperature, wind, pollutant and greenhouse gases as CO2 and CH4. To obtain the correct and high quality data, the parallel between the transmitting laser beam and optical axis of the receiving telescope upon a lidar system is of great importance. A high accurate and efficient active boresight mechanism is urgent needed for automating the lidar system especially for airborne and satellite lidars.The thesis proposes a design of an automatic boresight system for atmospheric lidar based on CCD imaging. The detail description of the principle, the validation experiment, the optical and mechanical design, and also the imaging process software are included. The outlook of the application to the real lidar system is also discussed.The thesis is consisted of six chapters:The first chapter describes the fundamentals of lidar remote sensing, including the principle, lidar equation and the lidar system. The importance of the active boresight mechanism and the review of boresight technique are also presented.The second chapter introduces the Dual-Wavelength Mie Lidar (DWL) used in this thesis, including the hardware, especially the receiving optical system and the control software. The validation experiment is carried out on this lidar system and the result shows the good practicality of the proposed active boresight method.The third chapter presents CCD image procedure. Based on the LABVIEW commercial software and the SDK kit provide by the CCD manufacture. The laser beam recognition method is proposed which is very important for the error analysis and the feedback control of the 2D direction of the transmitting laser.The fourth chapter gives the error analysis of the proposed active boresight method including the errors caused by the CCD image acquisition and the transmitting mechanism. The range of the tolerance errors is also discussed.The fifth chapter looks forward to the hardware development according the CCD imaging boresight method, including the optical and mechanical design of the lidar receiving system, the usage of the mirror adjustment mechanism and the feedback control.The last chapter summaries the main work has been done in this thesis. The importance and the innovations are pointed out. The shortages and the further extended work such as the expectation for high efficiency algorithm and method for image processing are given and discussed.