采用环形光束对卫星光通信发射系统的影响分析

发布时间：2018-04-21 02:13

本文选题：空间光通信 + 衍射光学　；参考：《哈尔滨工业大学》2017年硕士论文

【摘要】：随着信息社会不断发展,卫星激光通信的研究逐渐受到各国关注。由于终端光学系统各项指标对激光通信的影响重大,进一步优化其光学系统对提升终端性能显得尤为重要。对于卫星光通信终端的发射系统,使用环形光避开卡式天线次镜遮挡的过程中,发射光束的环形模型以及环形光与天线系统的参数设计对最终的优化结果有一定的影响。本文采用近年研究热度较高的双高斯环形光代替较早提出的双半高斯环形光,并与研究热度同样较高的平顶环形光进行对比分析。选择合适的环形光模型并研究输入光与光阑之间的最优匹配参数对提升天线能量利用率和深入了解环形光传输特点有着重要的意义。本文针对卫星激光通信环形光方案优化选型以及实现环形激光整形进行了以下工作:(1)对比分析了近年来提出的一种高效双高斯环形光代替陈旧模型后对卫星光通信的影响,以此来研究更适用于卫星激光通信的环形光模型。主要对三种模型的近场衍射中心能量、远场终端天线入瞳功率以及与之相对应的整形元件的成像精度进行了仿真。通过综合比较,平顶环形光远场入瞳功率峰值虽最高,但对参数匹配精确度要求较高;而双高斯环形光的稳定性最强,远场入瞳功率较高,容错能力更强,能够适用的系统更宽泛,各方面性能均较为优秀。(2)为求得更高远场入瞳功率所对应的双高斯环形光参数与环形光阑的参数匹配最优解,针对环形入射光与环形光阑的特殊通光性质,采用了一种新的分析方案对光学系统参数与入瞳功率的关系进行了全局考察。通过仿真获得能达到最高入瞳功率的最优参数匹配曲线图,对工程设计有一定的指导意义。(3)在设计环形光整形衍射光学元件的过程中,为保留GS算法运算速度快的优势,同时降低其迭代极值瓶颈,使用了一种几何追迹构建初值的方法,并将几何轮廓相位化后带入算法中。迭代结果显示构建的初值较平面相位和随机相位而言,成像图样均方误差更低。(4)为了解环形激光整形元件在工程实现中可能引入的误差对元件性能的影响,仿真分析了台阶量化、纵向及横向误差与衍射效率、峰值能量率以及成像均方误差的关系。仿真结果表明,适当增加台阶数可以很大程度上提高衍射效率,同时引入的横向误差对近场成像结果和远场入瞳功率的影响相较纵向误差而言更为严重。
[Abstract]:With the development of information society, the research of satellite laser communication has been paid more and more attention. Because of the great influence of various optical system indexes on laser communication, it is very important to further optimize the optical system to improve the performance of the terminal. For the transmission system of satellite optical communication terminal, the ring model of the emitting beam and the parameter design of the annular light and antenna system have certain influence on the final optimization results in the process of using annular light to avoid the blocking of the secondary mirror of the card antenna. In this paper, the double Gao Si ring light, which has been studied in recent years, is used to replace the double half Gao Si ring light, which has been put forward earlier, and is compared with the flat-top ring light with the same heat intensity. It is important to select an appropriate annular light model and study the optimal matching parameters between the input light and the aperture to enhance the energy utilization ratio of the antenna and to deeply understand the characteristics of the ring optical transmission. In this paper, the optimal selection of ring optical scheme for satellite laser communication and the realization of ring laser shaping are compared and analyzed. The influence of an efficient double Gao Si ring light instead of the old model proposed in recent years on satellite optical communication is compared and analyzed. The ring optical model which is more suitable for satellite laser communication is studied. The near field diffraction center energy of the three models, the power of the far field terminal antenna entering pupil and the imaging accuracy of the corresponding shaping elements are simulated. Through comprehensive comparison, although the peak-value of farfield entry pupil power of flat-top annular light is the highest, the accuracy of parameter matching is high, while the stability of double- annular light is the strongest, the power of far-field entry pupil is higher, and the fault tolerance ability is stronger. In order to obtain the matching optimal solution between the double Gao Si ring optical parameters and the annular aperture parameters corresponding to the higher far field pupil power, the system that can be applied is broader, and the performance of all aspects is better. According to the special optical properties of ring incident light and annular aperture, a new analytical scheme is proposed to study the relationship between the optical system parameters and the power of the entrance pupil. Through simulation, the optimal parameter matching curve which can reach the maximum input pupil power is obtained, which has a certain guiding significance for engineering design. In the process of designing ring light shaping diffraction optical element, the GS algorithm has the advantage of fast operation speed. At the same time, the bottleneck of iterative extremum is reduced, and a geometric tracing method is used to construct the initial value, and then the geometric contour phase is introduced into the algorithm. The iterative results show that the initial values constructed are lower than the plane phase and random phase, and the mean square error of the imaging pattern is lower. 4) in order to understand the effect of the errors that may be introduced in the engineering implementation of the ring laser shaping elements on the performance of the components, The relationship between step quantization, longitudinal and transverse errors and diffraction efficiency, peak energy rate and imaging mean square error is analyzed by simulation. The simulation results show that the diffraction efficiency can be greatly improved by increasing the number of steps, and the influence of the lateral error on the near field imaging results and the far field pupil power is more serious than that of the longitudinal error.
【学位授予单位】：哈尔滨工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TN929.1

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