基于光学章动的快速角度误差信号提取技术研究
文献类型：学位论文
| 作者 | 贺红雨 |
| 文献子类 | 硕士 |
| 导师 | 孙建锋 |
| 关键词 | 自由空间光通信 free space optical communication, fine tracking, angle error detection 精跟踪 fiber nutation 角度误差探测 local oscillator nutation 光纤章动 acoustic-optic deflector 本振光章动 piezo sacanner tube 声光偏转器 压电陶瓷管扫描器 |
| 其他题名 | Study on fast angle error signal detection technology based on optical nutation |
| 英文摘要 | 精跟踪是自由空间光通信的关键技术之一，而角度误差探测是精跟踪中的难点。精跟踪中角度误差探测的方式主要有两种，一种是将信号光分束到位置传感器的传统探测方式；另一种是利用光学章动产生的扰动的探测方式。利用章动探测角度误差的方式的优势是不需要分光，可以减少损耗，利用高速的光学章动可以实现高带宽的角度探测等。在广泛调研自由空间光通信及精跟踪中角度误差探测的基础上，本文分别提出两种光学章动探测角度误差的具体实现方案。 本文首先从空间光耦合到单模光纤的理论模型以及信号光和本振光的空间混频的理论模型入手，分析了基于光纤章动的角度误差探测和基于本振光章动探测角度误差的基本原理。 然后本文对产生章动的器件的特性进行了研究，建立了器件的理论模型。实现光纤章动的压电陶瓷管扫描器受到非线性效应，谐振效应和交叉耦合效应的影响，难以实现高速的精确控制。利用简单的模型计算得到了谐振频率和悬挂长度的关系，并在实验中通过测试找到工作在5kHz下合适的悬臂长度。实现本振光章动的声光偏转器是利用声光布拉格效应实现光束偏转的，具有无机械装置的优点，但是声光偏转器在使光束偏转时需要一定的渡越时间，而限制了章动频率。 其次本文提出了计算角度误差的算法，并进行了针对算法精度的仿真。算法中最基本的思想是利用两个不同时刻的光功率之比来得到一个关于二维角度误差的方程。在基于光纤章动探测角度误差的方案中，光纤的轨迹是连续的，得到的功率信号也是连续的，一个周期可以采样多个点得到多组方程。但是光纤章动存在随机误差，因此我们利用最小二乘估计点的位置。在本振光章动探测角度误差的实验中，采取的是四角度章动，功率信号是阶跃变化的，一个周期跳变四次，利用相差半个周期的外差信号可以得到两组方程，可以直接用这两组方程解出角度误差。仿真的结果表明这种算法在在角度误差比较大的时候，计算误差大，计算误差随着角度误差变小而变小。 最后分别针对两种探测角度的方案搭建了相应的实验系统。在光纤章动探测角度误差的实验系统中完成了耦合效率随角度误差变化曲线的测量，压电陶瓷管章动轨迹的调试工作，并完成了角度误差探测的工作。光纤章动的频率达到5kHz，测量误差为0.02接收视场角。在本振光章动探测角度误差的实验系统中完成了外差效率曲线随角度误差变化曲线测量，利用声光偏转器实现了本振光2kHz的章动，测量的误差精度优于0.05接收视场角。; Fine tracking is one of the key technology of free space optical communication, and angle error detection is the difficulty of fine tracking. There are two types of angle error detection in fine tracking: the first type is split signal beam into a QD or CCD and other position detector to detect angle error, the other type is using nutation to detect angle error. The advantage of using nutation to detect angle error is avoiding splitting light, reducing losses and high bandwidth with fast nutation. After widely investigate and survey on free space optical communication and angle error detection in fine tracking system, this paper respectively proposes scheme of angle error detection based on fiber nutation and local oscillator nutation. Firstly, this paper starts from the theoretical model of space light coupling into fiber and signal interfere with local oscillator in bulk optics. Coupling efficiency and heterodyne efficiency change with angle error was analyzed in multiple circumstances. Meanwhile we measured the curve of coupling efficiency change with angle error and heterodyne efficiency change with angle error, they are both coincide with theoretical curve. There is Piezo tube scanner for fiber nutation. Next, this paper researched on character of nutation component, and theoretical model of the component was built. The piezo tube scanner for fiber nutation suffer from effect of vibrations, nonlinearity effects and cross-coupling effect, thus can’t be precisely controlled. Simple model was used to calculate the relationship between resonant frequency with hanging length. We also find proper hanging length at 5kHz for experiment through test. The acousto-optic deflector for local oscillator nutation is based on the Bragg effect, the advantage of acousto-optic deflector is nonmechanical. However, there is transit time for acousto-optic deflector which limit the nutation frequency. Then, angle error detection algorithm was coming up with in this paper, as well as simulation on precision of algorithm. The basic idea of algorithm is obtaining an equation of bidimensional angle error from the ratio of laser power of different time. In the scheme of fiber nutation angle error detection, the trace of fiber nutation is sequential, which means the signal of laser power is sequential, we can sample multiple point of power and get more than one equation. However, there is random error for trace of fiber nutation, thus we use least square method to estimate the angle error. In the scheme of local oscillator nutation angle error detection, four angle nutation was adopted, the signal of power is step change, there is four steps in a nutation period, therefore we can get two equation and solve equation set to get angle error. The simulation result shows that the calculation error is large when angle error is large, along with the decline of the angle error the algorithm gradually convergence. Finally, corresponding experiment setup was built aiming at two types of angle error detection. In experimental system of fiber nutation angle error detection, the coupling efficiency change with angle error was measured, and the nutation of piezo tube scanner was accomplished, as well as, the angle error detection. The nutation frequency of fiber reached to 5kHz, the measured error is less than 0.02 receiving angle. In local oscillator nutation angle error detection experimental system, the heterodyne efficiency change with angle error was measured, 2kHz natation was realized using acoustic-optic deflector, and the measured error is less than 0.05 receiving angle. |
| 学科主题 | 光学工程 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/31093]  |
| 专题 | 中国科学院上海光学精密机械研究所 |
| 作者单位 | 中国科学院上海光学精密机械研究所 |
| 推荐引用方式 GB/T 7714 | 贺红雨. 基于光学章动的快速角度误差信号提取技术研究[D]. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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