星间激光通信终端及其实验室检测平台光学系统研究

	星间激光通信终端及其实验室检测平台光学系统研究
	吴从均
学位类型	博士
导师	颜昌翔
	2014-07
学位授予单位	中国科学院大学
学位专业	光学工程
摘要	星间激光通信具有信息容量大、光学增益高、高度抗干扰和抗截获能力等突出优点，得到了国内外广大关注。激光通信中光学系统支路繁多、波像差要求极高，对光学元件的加工和装调要求非常严格，所以研究合理的光学系统结构，建立像差和通信性能参数之间关系，可以有效指导设计、加工和装调；通信终端通信距离非常远，难以在地面开展行之有效的试验，因此研制终端检测所需的实验室平台和空间通信链路模拟设备是评估终端整体性能的有效途径。针对通信终端不同支路的作用特点和探测方式，本文建立了发射系统单色像差和远场激光能量分布、接收系统单色像差和捕获光斑精度、接收能量以及通信系统误码率之间的关系，并利用建立的关系分析了单色像差对于指向、捕获精度和误码率的影响；分析结果表明，慧差和倾斜将严重影响指向和捕获跟踪精度，分别呈三次和线性关系，像差对于误码率的影响和理论误码率大小有关，理论误码率越低，通信终端对光学系统要求越高；通过对IM/DD和BPSK调制解调方式的分析，指出了基于BPSK相干通信对光学系统波像差要求要高于IM/DD非相干激光通信的依据；通过对不同光束相干时外差效率的研究，指出在追求较高外差效率时，需根据探测器、相干光束形式来确定光束参数。根据GEO通信终端的使用要求和特点，提出了基于BPSK调制GEO通信终端的光学系统要求。在该指标下，比较了采用透射、离轴反射、卡式和改进卡式结构设计终端天线时对体积、加工、装调的要求。结果表明改进的卡式结构具有体积小、加工难度低、装配公差松的优点，非常适合于星间通信终端的应用，并采用改进的卡式结构设计了基于BPSK调制的GEO终端光学系统，分析了该光学系统的性能。通过对国外激光通信终端实验室测试设备的功能分析，并结合通信终端光学系统特点，提出了测试通信终端所用的实验室检测平台的光学系统原理和设计要求，根据光学要求设计了该测试平台，平台采用全反射结构、利用分束器反射和透射相结合的结构消除光学系统的偏振分离，这使得平台不仅能测试不同激光波长的终端、又能对不同调制形式下的终端进行性能评估；平台调试结果表明，平台不能满足指标波像差要求，通过分析平台波像差的特点，提出了采用掩模相位板补偿系统波面的方法，并对补偿效果和可行性进行了分析和实验验证，结果表明该方法稳定可行；根据研制的测试平台，对应的设计了能够模拟空间可变距离光束传输的实验室系统，系统采用全反射级联、物像同时移动实现，系统结构明确、体积小，精度分析表明系统能够实现很高精度的能量稳定度，满足测试系统要求
其他摘要	Inter-satellites Laser communication Terminals (LCT) have got widespread atte- ntion now, dues to its advantages such as huge capacity of information, high optical gain and high anti-interception ability. The optical system of LCT has the characteristics of high imaging quality requirement and multi-channel used, which give a great pressure on optical manufacture and alignment. As to direct optical design, manufacture and alignment, studying on the relationship between aberration and communication property and developing more reasonable optical structure are very significative. Besides, it’s difficult to promote effective experiment on ground because of the far distance among the communication LCT, therefore, developing test platform for LCT and designing the space link models to evaluation LCT in laboratory is very indispensable. Based on different detection model and the function peculiarity of different channels, the relationship between primary monochrome aberrations of transmit antenna and far field laser intensity distribution, primary monochrome aberrations of receiving terminals and acquisition accuracy, acquisition intensity, and bit error rate(BER) were established. The relationship between pointing error, acquisition error, BER and aberration were analyzed by numerical method. The results indicate that tilt and coma have a great effect on pointing error and acquisition error, liner and cubic curve can stand its relationship, respectively. The effects of aberration to BER were determined by the ideal BER, the lower BER needs higher requirements of the optical system. Coherent heterodyne detection based on BPSK modulation have rigid requirement on aberration, compared to uncoherent detection based on IM/DD modulation. The analysis of heterodyne efficiency with different coherent beam shows that the parameters of the beam rest with the detector parameters and coherent beam styles so as to obtain high heterodyne efficiency. On the basis of the GEO LCT’s working mode and application feature, optical index of GEO LCT based on BPSK modulation were presented. In order to develop a suitable antenna optical structure, transmission, reflection of off-axis, classical cassegrain and developed cassegrain types were compared upon manufacture, alignment and test. The results states developed cassegrain have the advantages of smaller size, easier manufacture and looser tolerance, and is propitious to be used for optical antenna of inter-satellite communication. Using Zemax software, the optical system was designed with developed cassegrain structure, and its performance were also discussed. According to the function analysis about laboratory test equipment of LCT in aboard and LCT’s characteristic, principle and optical requirement of LCT’s lab test and link model system were brought forward, and also designed the optical system upon the requirement with reflection structure, the beam splitter’s reflection and transmission were used to compensated the polarization diverse. The system can be used to test different LCT that not only different communication wavelength, but different types of modulation. Because of the manufacture levels and highly image quality demand, the alignment results were not satisfied for the optical requirements proposed. After analyzed the wavefront’s features, method using mask phase plate to correct the wavefront was discussed. The result indicated that mask phase plate can improve the wavefront to its requirments with practicable process. The space link model was also designed based on the test equipment, the theoretical analysis of the space link model shows its can model 103km~105km communication link, which can satisfied the most LCT payload used in inter-satellite communication.
语种	中文
文献类型	学位论文
条目标识符	http://ir.ciomp.ac.cn/handle/181722/41485
专题	中科院长春光机所知识产出
推荐引用方式 GB/T 7714	吴从均. 星间激光通信终端及其实验室检测平台光学系统研究[D]. 中国科学院大学,2014.

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