合成孔径激光成像雷达大视场光学外差探测技术研究
文献类型：学位论文
| 作者 | 卢栋 |
| 学位类别 | 硕士 |
| 答辩日期 | 2013 |
| 授予单位 | 中国科学院上海光学精密机械研究所 |
| 导师 | 孙建锋 |
| 关键词 | 合成孔径激光成像雷达 光学外差探测 外差效率 信噪比 视场角 阵列探测 |
| 其他题名 | Research on Wide Field-of-View Optical Heterodyne Detection for Synthetic Aperture Imaging Ladar |
| 中文摘要 | 光学外差探测是基于两光束干涉效应来实现对微弱信号的探测，因此也称为相干探测。随着激光技术的发展，相干探测所表现出的众多优点使其已经或正在取代直接探测而应用于空间激光应用系统，空间合成孔径激光成像雷达（SAIL）就是最典型的应用之一。SAIL的原理来源于微波合成孔径雷达，是目前能够在远距离实现厘米量级分辨率的唯一光学成像手段。SAIL因具有超高的成像分辨率及全天候实时快速成像的能力，在军事、航天、气象等方面有着广阔的应用前景。由于激光波长比微波小3~6个数量级，而光学器件比信号波长大3~6个数量级，SAIL的成像又带来了空间域和时间域光学波段的难题，且更易受到大气扰动、平台抖动和元器件稳定性等因素的影响。SAIL常工作于光学衍射极限状态，接收视场和成像幅宽较小，因此保证系统信噪比不降低情况下，研究如何增大SAIL的接收视场和探测能力，对实现大面积宽幅成像有重要意义。 论文首先综述了合成孔径激光成像雷达基本原理，国内外进展现状及SAIL的独特优势和应用领域；介绍了光学外差探测技术原理，给出了外差探测中重要的两个评价参量外差效率和信噪比的定义式。在此基础上，主要做了如下几方面工作： 1.对常用的两种接收结构做了理论分析，采用简化设计的SAIL系统结构，推导了高斯信号场和平面波信号场的波面点目标衍射方程，并得出其远场可归一化表示。基于实际系统，讨论了本振光斑、信号光斑、光场类型及雷达运动对系统外差效率的影响；并数值模拟多点目标成像，结果和理论分辨率基本一致，验证了透镜在合束前结构具有更大接收视场。 2.从接收视场角、信号光可探测能力及系统的信噪比三个方面分析论证了传统的望远镜接收、透镜接收及望远镜自差接收这三种典型外差接收结构的优缺点；结果表明阵列探测器结构具有视场大，探测能力强，信噪比高的优点，与Siegman光学外差接收天线理论吻合，可成为大视场SAIL外差探测系统的选择。 3.对合成孔径激光成像雷达大视场接收结构做了验证性实验，并给出相关讨论和误差分析，与理论解释相符。 |
| 英文摘要 | Optical heterodyne detection can receive weak signal based on the two-beam interference effects, also known as coherent detection. With the development of laser technology, direct detection has been or is being replaced by coherent detection owing to its many obvious advantages in space laser application systems and space Synthetic Aperture Imaging Ladar (SAIL) is the typical application of coherent detection. Referring to the principle of Synthetic Aperture Radar in radio frequencies, SAIL is the only one optical imaging means able to achieve centimeters-class resolution in the long-range order. Due to its high imaging resolution and 24-hour real-time fast imaging ability, SAIL will have wide application prospects in military, aerospace, meteorological and etc.Because of laser wavelength smaller than microwave for three to six orders of magnitude, and optical devices bigger than laser wavelength for the same orders of magnitude,SAIL technology broughts some new optical problems in spatial-domain and time-domain and is more easily influenced by atmospheric disturbances, platform jitter,component stability and other factors. Often working in the optical diffraction limit state, SAIL’s receiving field of view and imaging width are grater small.Thus, ensuring the system signal-to-noise ratio,how to increase the field of view and detection capability of SAIL has a important significance. The paper firstly introduces the basic principle of Synthetic Aperture Imaging Ladar, progress status at home and abroad, and SAIL''s unique advantages and applications;Then gives the basic theory of optical heterodyne detection technology and the definition of heterodyne efficiency and signal-to-noise ratio. On above basis, the thesis includes the following work: 1. Theoretical analysis of two common receiving structures is given.According to simplified SAIL system architecture, diffraction equations of point target of Gaussian signal field and plane wave signal field are derived,and can be normalized presented.Based on the real system, the impact on system heterodyne efficiency of the local oscillator spot, signal spot, the type of signal field and ladar movement is provided. Numerical simulation of multi-target imaging is accomplished and the results show that the lens on the front of beam combiner structure has larger receiving field-of-view, which meets with theoretical analysis. 2. Considering the receiving FOV,signal light detection capability and signal-to-noise ratio of corresponding system , relative merits of three typical heterodyne receiving structures of telescope receiving, focusing lens receiveing and telescope for self-heterodyne are discussed. The results show that array detection structure has a large field of view, strong detection capability and high signal-to-noise ratio, which meet with Siegman’s optical heterodyne receiving antenna theory. 3. Validation experiment of SAIL for wide field of view heterodyne receiving structure is accomplished.Relevant discussions and analysis are presented, consistent with the theoretical explanation. |
| 语种 | 中文 |
| 源URL | [http://ir.siom.ac.cn/handle/181231/16788]  |
| 专题 | 上海光学精密机械研究所_学位论文 |
| 推荐引用方式 GB/T 7714 | 卢栋. 合成孔径激光成像雷达大视场光学外差探测技术研究[D]. 中国科学院上海光学精密机械研究所. 2013. |
入库方式： OAI收割
来源：上海光学精密机械研究所
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