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题名:
自适应光学系统的光束质量影响问题研究
作者: 叶红卫
学位类别: 博士
答辩日期: 2009-06-06
授予单位: 中国科学院光电技术研究所
授予地点: 光电技术研究所
导师: 饶长辉
关键词: 自适应光学 ; 光束质量 ; 变形镜 ; 像差解耦 ; 联合闭环
其他题名: The Study on the Influence of Beam Quality for an Adaptive Optics System
学位专业: 光学工程
中文摘要: 自适应光学技术经过近三十年的不断发展,已经在天文观测高分辨率成像、激光大气传输,光学系统光束质量改善等很多领域取得了比较成功的应用;然而自适应光学系统作为大型光学系统的一个组成部分,需要与其他光学系统相配合使用。如果系统中存在较大的抖动误差、高空间频率像差或较大的光强不均匀性误差,就会对自适应光学系统的光束质量有很大的影响。深入分析影响自适应光学系统校正效果的各种因素,合理评价自适应光学系统的校正效果,是当前自适应光学领域的一个很重要的研究课题。 本文研究的目的是从实际工程入手,针对工程中遇到的实际问题,通过理论分析和大量的仿真计算以及实验测试,深入分析影响自适应光学系统校正能力的各种因素。为提高自适应光学系统的光束质量提供理论依据。 本文首先分析了光学系统光束抖动对光束质量的影响,给出了理论解析公式。研究表明光束抖动对光束质量影响极大,必须引起足够重视。要想提高全系统的光束质量,光束抖动误差必须得到严格的控制,否则将使自适应光学系统校正能力无法体现。这部分研究结果对于穿过大气的成像、激光能量传输等应用领域具有重要意义。 其次分析了光学系统的静态和动态Zernike像差与对光束质量因子间的影响,推导了根据zernike波像差及其动态方差大小估算光束质量 因子的计算公式。指出在自适应光学系统设计中,只有既要注意低阶像差校正,又要注意高阶残差对光束质量的影响,才能使系统得到更好的校正效果。 另外分析了近场光强分布及高空间频率像差对最终远场光斑光束质量的影响。通过理论分析和计算机仿真计算,指出振幅调制度影响远场光斑弥散光强的大小,近场强度调制频率影响高阶散斑分布的区域。当近场光强分布的填充因子f>0.5时,近场光强分布对系统光束质量的影响就可以忽略不计。如果光强足够强还会引起附加的高空间频率波像差,自适应光学对这部分波像差校正能力较弱,波像差均方根RMS超过λ/20就会使光束质量明显下降,但对中心亮斑的形态影响不大。因此对于关心能量集中度指标的高能激光系统而言,用峰值斯特列尔比或桶中功率比要比用光束质量β因子要更合理。相关研究对于自适应光学系统工作的对象-激光光束提出新的改进方向。。 最后针对目前对自适应光学空间校正精度和校正能力需求很高,但高精度变形镜制作困难的实际情况,提出一种用单波前传感器控制多个变形镜联合校正的新的控制算法,通过对像差的解耦和限定校正实现对畸变波前的高精度的实时校正。搭建了基于单波前传感器控制双变形镜联合校正的自适应光学系统,用模式控制与直接斜率控制相结合的方法,实现了对光学系统静态像差和动态像差的闭环校正。通过这种控制方法,可以在现有技术条件下大幅度提高自适应光学校正能力。为提高自适应光学系统的校正能力提供了新的思路。 总之,本文相关研究工作对于现有自适应光学系统的改造和新型自适应光学系统的研制有重要的指导意义。为合理评价自适应光学校正能力,提高自适应光学系统校正效果积累了一定程度的理论知识和工程经验。
英文摘要: After three decades of development, adaptive optics(AO) technology has been applied successfully to high resolution imaging of astronomical observation, laser propagation in the atmosphere, improvement beam quality of the optical system, and many other fields; however, as a part of large optical system, AO system need usually integration with other optical systems, therefore any error of a subsystem affects the evaluation of correction effect of AO. It is important to deep analyze various influence factors on correction and evaluate correction ability of an AO system. The goal of this paper discusses mainly deep analysis various influence factors on correction effect of AO such as beam jitter, static and dynamic Zernike aberration, near-field intensity distribution and high spatial frequency aberration, and then provides the proof in principle with improvement the beam quality of AO through numerous theory analyses, numerical simulations and test by experiments under practical engineering environment. Firstly,the dissertation analyzed systemically effect of beam jitter on beam quality and obtained analytical formulae. It is indicated that beam jitter affects beam quality strongly,so the importance should be attached to it. The error resulted from beam jitter must be controlled to improve the beam quality of the whole system; otherwise the correction capability of AO can not be achieved. Secondly, the thesis analyzed the effect of static and dynamic Zernike aberration of the optical system on beam quality β factor, and derived the formula of estimating the beam quality factor from the Zernike coefficients and dynamic variance of aberration. It is pointed out that the better correction performance of the AO system had be achieved none but the effect of lower-order aberration and higher-order residual error on beam quality were compensated. Additionally, the effect of near-field intensity distribution and high spatial frequency aberration on beam quality was analyzed. It is proposed that lever of amplitude modulation influences the dispersion intensity of far-field spot and near-field intensity modulation frequency affects the distribution area of higher-order scatter spot by theory analysis and computer simulation. When f>0.5(f refers to filling factor of near-field intensity), the effect may be ignored. If the intensity is enough large to cause additional higher spatial frequency aberration, the beam quality degrades but does not contribute to the shape of the central light spot when the aberration RMS is more thanλ/20, because AO is not good at correcting the aberration. Thus, in order to characterize the beam quality, it is reasonable to characterize the beam quality using peak strehl ratio or power in barrel rather than β factor for high energy laser system where the specification of energy focusing is regarded highly. Based on the research efforts presented in the paper, a potential path to improve laser beam of AO system was proposed. Finally, to meet the requirement of high precision for spatial correction and solve the problem of the producing high precision deformable mirror, a new algorithm is proposed that controls several deformable mirror corrections using single wave-front sensor, decoupling aberration and limiting of wave-front aberration to achieve high precision real-time correction. An adaptive optical system was set up based on the scheme of single wave-front sensor jointed deformable mirror correction, and the close-loop correction of static and dynamic aberration was implemented by the way of pattern control combined with direct slope control. With the above methods, the correction performance can be improved significantly under the existing condition. In a word, numerous works mentioned will provide a new idea with improvement the correction capability of AO system. Overall, it is meaningful for the research efforts presented in the paper to improve the existing AO system and develop new AO systems. And fruitful theoretical and practical research works have been done for a reasonable evaluation of correction ability of adaptive optics and improvement of correction effect of adaptive optics system.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.ioe.ac.cn/handle/181551/170
Appears in Collections:光电技术研究所博硕士论文_学位论文

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Recommended Citation:
叶红卫. 自适应光学系统的光束质量影响问题研究[D]. 光电技术研究所. 中国科学院光电技术研究所. 2009.
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