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题名:
惯性约束聚变装置中自适应光学系统的性能和波前控制方法研究
作者: 黄林海
学位类别: 博士
答辩日期: 2009-06-01
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: 姜文汉
关键词: 惯性约束聚变 ; 自适应光学 ; 光学仿真 ; 波前控制
其他题名: The Research of control method and performance for Adaptive Optics in Inertial Confinement Fusion (ICF) facility
学位专业: 光学工程
中文摘要: 自适应光学(Adaptive Optics, AO)技术通过实时的校正惯性约束聚变(Inertial Confinement Fusion, ICF)装置中的静态和动态像差,保证装置输出光束的质量,改善靶点焦斑能量分布,为成功实现激光点火奠定基础。然而,自适应光学与ICF装置中的非线性效应、倍频转换等光学效应的相互影响关系却一直很模糊,致使自适应光学技术在实际运用中产生问题时无法确定其根源,阻碍自适应光学技术在ICF装置的进一步发展。此外,合适的波前控制方法是充分发挥ICF装置中自适应光学的校正能力的重要因素,是自适应光学技术在ICF装置中进一步发展的重要前提。因此,本文的研究内容分两部分进行,第一部分,在简要分析国内外ICF装置及其自适应光学发展历史的基础上,通过建立首套含自适应光学的ICF装置仿真分析程序,给出不同AO配置下的ICF装置波前校正效果,并以数值仿真的形式解答自适应光学与ICF装置中各光学效应间的关系;第二部分,初步探索了利用多个已知像差进行Gerchberg-Saxton (G-S)相位反演的算法和随机并行梯度下降(Stochastic parallel gradient descent, SPGD)控制算法两种波前控制方法在ICF装置中使用的可行性。 本文首次提出修正型高斯影响函数表达式,并据此建立首套含自适应光学的ICF装置仿真程序。修正型高斯影响函数是对原有高斯影响函数的角向和径向修正后获得的结果,其产生的影响函数面形更接近实测结果;结合准确的哈特曼仿真模型,建立与实际校正效果相近的自适应光学模型。与此同时,根据相应的物理光学原理,先后建立光的线性传播,光的非线性传播,光的增益,光的倍频,连续随机位相板等模型;从而建立准确的ICF装置仿真模型。最后,利用非方形孔径位相解缠绕方法将ICF装置的仿真模型和自适应光学仿真模型结合起来,并以目前“神光III”原型装置和计划的“神光III”主机装置中可能存在的各种自适应光学配置为背景,利用合理的像差生成方法,完成全光路仿真。仿真结果表明:将变形镜放置在腔镜处且光路中不存在旋光装置时,经自适应光学校正后,在光传输的各个阶段像差均维持较小,校正效果也较理想。 利用仿真程序,研究了自适应光学与非线性效应、倍频效应之间的相互关系以及自适应光学自身共轭对波前校正结果的影响。研究结果表明:1)非线性效应不会改变自适应光学的校正结果;2)自适应光学波前校正可以改善因非线性引起的光强畸变,但是,自适应光学技术不能消除因非线性而引起的自聚焦效应;3)SGIII的像差对倍频器转换效果的影响很小,自适应光学波前校正可以改善倍频器输出的光强均匀性;4)在保证ICF装置严格共轭的情况下,自适应光学系统短距离偏离共轭位置对其在ICF装置中校正效果的影响是可以忽略。 本文第二部分对G-S相位反演的算法和SPGD优化控制算法进行了初步的探索。经理论、仿真和实验验证,结果表明:1)在不考虑远场光斑和已知像差的测量误差条件下,利用变形镜影响函数可以准确的反演出探测像差。即使存在一定测量误差,这种多帧G-S算法仍然能够反演出较准确的像差;2)即使装置中存在旋光系统且变形镜放置在腔镜位置,SPGD算法仍可作为ICF装置中自适应光学的波前控制方法。仿真和实验结果还表明,SPGD算法可以避免因存在旋光系统和变形镜的两次校正而引起的校正相消,导致驱动器行程不断增加的不稳定结果。 通过建立首套含自适应光学ICF装置仿真程序,解答自适应光学与ICF装置中光学效应间的关系,为下一步优化设计ICF装置中自适应光学的关键器件(变形镜、哈特曼传感器)及其之间的匹配关系打好基础;通过探索多种波前控制方法在ICF装置中的使用为更灵活、更高效的使用ICF装置中自适应光学系统奠定基础。
英文摘要: By compensating static and dynamic optical wavefront distortions in ICF facility real-timely, the adaptive optics (AO) system can improve the quality of light beam and make the far-field intensity distribution more centralization, which provides foundation for successful ignition. However, the obsolescent relationship between AO correction and nonlinear effect, frequency conversion leads to difficulties in determining reasons for problems meeting in experiment, which plagues the development of AO in ICF facility. Besides, proper means of wavefront control method is needed for exerting full the correction capability of AO system and for further development of AO system in ICF facility. Therefore, the paper consists of two components. In the first component, a beam propagation codes with AO system is modeled for ICF facility, and the relationships is cleared by those codes. The feasibilities of the Gerchberg-Saxton (G-S) retrieval method using multiple known phases and Stochastic parallel gradient descent (SPGD) algorithm in ICF facility are primarily explored in section 2. The Modified Gaussian influence function (MGIF) of deformable mirror actuators is first introduced in this paper and the beam propagation codes with AO system for ICF facility are indexed based on the MGIF. The modified expressions for both azimuthal and radial directions are presented, which provides much better performance in data fitting. Combining with the model of Shack –Hartmann sensor (SH), the model for AO system is built, which agrees with the actual one. Simultaneity, based on the theories of physical optics, the linear propagation, nonlinear propagation, amplification, frequency conversion and continuous phase-plate are modeled respectively, and the close integration of those models built the accuracy model for ICF facility. Finally, a new method to solve the problem of non-square unwrapping phase is presented to reconcile the model of ICF facility and model of AO system. On the background of actual scheme of AO in ‘Shen Guang III’ facility and suitable aberrations, simulations are performed. The results indicate that the corrected laser beam possesses a smaller aberration for the duration of propagation in ICF facility if there are not beam rotations in ICF facility and the DM is placed at the cavity mirror of multi-pass amplifier. By mean of codes built above, the impact of non-conjugation of AO system and the relationship between AO system and non-linear effect, frequency conversion are studied. The conclusions are as follows: 1) Nonlinear effects do little difference to the correction capability of AO system. 2) The correction of AO system can somewhat improve the uniformity of laser beam intensity distribution, but fail to eliminate self-focusing effects. 3) The effect of frequency-tripling for laser beam with aberrations in SGIII is small, and the AO system can also improve the uniformity of laser beam intensity distribution. 4) Deviating from conjugation position for short rang does little effect to the correction result of AO system, on condition that ICF facility is self-conjugation. By theory analysis, simulation and experimental verification, the research of the wavefront control methods of G-S retrieval method and SPGD algorithm in ICF facility have come to the conclusions that: 1) Ideally, the mult-frame G-S retrieval method can reach the phase accuracy using the influence function of DM, even in the case of certain measurement errors, the method works well. 2) It is feasible that the SPGD algorithm can be used as wavefront control method in ICF facility even in the conditions that optical rotation exists in the ICF facility. The result of simulation and experiment also suggest that SPGD algorithm capable of avoiding instability of actuators caused by optical rotation and twice corrections of DM. With the utilization of the codes built above which clear the relationship between AO system and optical effects in ICF facility, we are ready to prepare for the optimization design of deformable mirror (DM), Shack –Hartmann sensor (HS) and relationship between them. Moreover, the explorations of new ways of wavefront control methodes contribute to more flexible and efficient AO system in ICF facility.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.ioe.ac.cn/handle/181551/337
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:
黄林海. 惯性约束聚变装置中自适应光学系统的性能和波前控制方法研究[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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