星地激光通信中光束传输仿真和链路特性关键技术分析-simulation of beam transmission and analysis of key technologies of link characteristics in satellite-ground laser communication.docx

dissertation are as follows:By summarizing the multi-phase screen simulation method of light beam transmission in atmospheric turbulence base on standard parabolic equation, this dissertation elucidated how to choose grid parameters when discretized the turbulence and optical field. By the numerical analysis of the practical links, we found out that the existing methods could not guarantee the reliability when the divergence angle was larger than 100μrad. For such kind of condition, the characteristics of the maximum spatial sampling rate was discussed, and an improved method using multi-phase screen was developed with the examples of divergence angles of 100urad and 1.35mrad in horizontal links. The results showed that by using the improved method, the characteristics of the light field and the theoretical expectation as well as the experimental result were almost the same, which proved the reliability and practicability of the new method.When the light beam divergence angle is relatively large, with the links grow longer, the simulation needs very large memory of the computer, sometimes even larger than the capability of the experimental computer. By analyzing respectively the relationship of accuracy of simulation with the value of grid parameters and the conditions of different links, this dissertation not only proposed an optimal grid parameters solution, but also fitted out an empirical formula of the relationship of the optimal grid parameters with the divergence angles and the lengths of the links, which helped a lot to determine the value of grid parameter and lowed down the memory requirement while guaranteeing the reliability during the procedures of simulation.For the design of the acquisition, pointing, tracking (APT) system, the influence of atmospheric refractivity on APT and pointing in advance. A formula based on the the wavelength of light, air temperature and atmospheric pressure, considering the air temperature and atmospheric pressure as functio