傅里叶望远镜成像关键技术研究

	傅里叶望远镜成像关键技术研究
	于树海
学位类型	博士
导师	王建立
	2014-07
学位授予单位	中国科学院大学
学位专业	机械电子工程
摘要	傅里叶望远镜(Fourier Telescopy，简称FT)综合了激光主动照明和合成孔径成像技术的优势，使得成像分辨率和系统信噪比之间相互分离，易于系统扩展，采用光桶（不要求共相的拼接大面积反射镜）即可作为返回信号的接收装置，降低了系统研发难度和成本，可对远距离、暗、小目标高分辨率成像探测，分辨率理论上无穷大，是非常规光学成像技术的重要方向之一，特别是在对地球同步静止轨道卫星目标的高分辨率成像探测方面拥有独特的优势，具有较大的应用前景。本文在现有研究的基础上，主要就以下几个方面进行了深入的分析研究： 1、介绍了FT成像系统基本原理：从时空编码入手，阐述了傅里叶望远镜可以突破成像衍射极限的理论依据；结合T型发射配置模式，介绍了相位闭合技术，阐述了其消除大气Piston和发射系统的粗大相位差异的基本原理；对图像重构算法进行了研究，进而完成了整个系统原理的搭建。为接下来的研究打下了理论基础。 2、在基本原理的基础上，提出将发射望远镜非均匀间隔作为发射配置模式，在同等发射器数量的条件下，可以采集到目标的高频分量，还原目标更为精细。由补零到非均匀傅里叶变换,再到缺失频率估计，完善了非均匀配置重构算法。为了降低采样频率，引入非均匀采样技术，结合非均匀傅里叶变换和幅值衰减法，通过数值模拟验证了该方法的可行性。分析表明该方法不仅能降低采样频率，并且对噪声的敏感性和传统的FFT方法基本一致。 3、作为主动成像技术，光束传输必然受到大气扰动的影响，分析指出：傅里叶望远镜可以忽略大气对光强的影响，并且当发射系统海拔在900m左右时，傅里叶望远镜成像系统主要受到大气2、3阶倾斜像差的影响。在此基础上，分析了倾斜项校正精度对系统的影响。 4、分析了光束间移频频差及目标运动对FT系统的影响，采用全相位谱时移相位差方法对频差进行了校正，完成了静止目标的外场实验数据全处理，验证了方法的可行性，并对运动目标进行了成像模拟，发现该方法完全不受目标运动的影响，可用于实际工程系统的数据处理。 5、结合理论分析，完成了实验室内和外场实验验证研究，证明了FT成像系统的可行性，验证了系统不受下行链路大气扰动的影响。为实际工程系统的最终实施提供了参考，并对大功率长相干激光器和光学延迟线进行了研究。
其他摘要	Fourier Telescopy, abbreviated as FT, integrates the advantages of laser active lighting and synthetic aperture imaging technique so that imaging resolution and system SNR are separated from each other. By the way, it is easy to expand the system. Using light buckets can be seen as the return signal receiving device, reducing the difficulties and costs for system research. As one of the most important directions of non-conventional optical imaging technique, it has a big applying prospect in imaging and detecting the targets which are in a distant, dark and small condition with a high resolution. In theory, resolution is countless large, especially, it has unique advantage in imaging and detecting GEO satellites with high resolution. On the basis of the existed research, this thesis mainly analyses and studies the following aspects thoroughly: 1. This thesis introduces the basic theory of FT imaging system. It states the theoretical basis that Fourier Telescopy can be used to break through imaging diffraction-limited, beginning from space-time encoded theory. Combining the T type emitter configuration mode, it gives an introduction about phase closure, and the basic theory of eliminating the Piston phase difference have also been explained. The research on algorithms of reconstruction images has been studies and the theory formation for the whole system has been completed as well. It has laid a theoretical foundation for the following research. 2. Based on the fundamental theory, this thesis puts forward non- uniform spacing as launching configuration mode. Under the situation of using the emitters of the same number, it can collect the higher frequency of the target so that it will be elaborate to return to the original condition of it. From set zeros to non-uniform Fourier Transform(NFT) and estimating deficiency frequency, non-uniform configuration reconstruction algorithm has been perfect. In order to reduces sampling frequency and import non-uniform sampling technique, it has validated the practicability of the method combined with NFT and amplitude damping. From the analysis, it is obvious that this method can not only decrease sampling frequency, but also go to the same noise sensitivity with traditional Fourier Transform(FT) methods. 3. As active imaging technique, it must be influenced by atmospheric disturbance when light transmission. It can be seen from the analysis that Fourier Telescopy can ignore the influence of disturbance on intensity. What is more, it’s imaging system is mainly effected by 2、3 tilt modes when the altitude of the launching system is at about 900m.On this basis, it has analyzed the influence of accuracy of tilt correction on the system. 4. Having analyzed the effects of frequency errors of arbitrary two beams and the target movement to FT system, it takes the method of all phase time shift phase difference correcting spectrum to adjust frequency errors. Field experiment data processing has been finished and the practicability also been checked. Furthermore, it has simulated the image aimed at the moving target. It is evident that this method is not influenced by the target movement and it can be used in dealing with the data in the practical project system. 5. Analyzed integrated with the theory, the experiment has been completed both in the lab and outside. It testifies the feasibility of the system and checks that imaging system is not influenced by down-link atmospheric disturbance. It has offered the reference to the practice of project system. Besides, this thesis has studied a lot optics delay thread and laser of high power and long coherence.
语种	中文
文献类型	学位论文
条目标识符	http://ir.ciomp.ac.cn/handle/181722/41495
专题	中科院长春光机所知识产出
推荐引用方式 GB/T 7714	于树海. 傅里叶望远镜成像关键技术研究[D]. 中国科学院大学,2014.

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