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题名:
自适应光学系统模式复原算法和控制算法的优化研究
作者: 李新阳
学位类别: 博士
答辩日期: 2000
授予单位: 中国科学院光电技术研究所
授予地点: 中国科学院光电技术研究所
导师: 姜文汉
关键词: 自适应光学系统 ; 大气湍流 ; 模式复原算法 ; 自适应控制算法 ; 优化
中文摘要: 自适应光学系统实时校正动态波前误差,使光学系统具有了适应外界环境变化,始终保持最优工作状况的能力。自适应光学系统的补偿效率受到被校正波前误差的时间-空间特性与系统的时间-空间特性匹配程度的制约。寻求波前误差特性和系统性能的最佳匹配始终是自适应光学技术发展和系统设计研制中的重要问题。在一定的硬件条件下,复原算法和控制算法具有一定的调整灵活性。其中复原算法直接影响自适应光学系统的空间补偿特性,而控制算法决定了系统对时间扰动信号的抑制能力。要使自适应光学系统在各种工作环境下均达到最优状态,就要对自己的空间域补偿能力和时间域抑制能力分别进行优化,也就是说要分别研究自适应光学系统中复原算法和控制算法的优化问题。合适的复原算法和控制算法不但可以提高自适应光学系统的灵活性和通用性,而且可以充分发挥系统的潜力,改善体系的校正效果。在复原算法优化方面,本文通过Zernike模式和K-L模式分析了大气湍流畸变波前的空间特性。通过变形镜本征模式和哈特曼本征模式,分析了自适应光学系统中变形镜波前校正器和哈特曼波前传感器的空间特性,以及整个系统的空间特性。其中哈特曼本征模式的新概念是本文在研究哈特曼传感器的噪声传递特性时首先提出来的。本文还分别研究了基于Zernike模式、K-L模式、变形镜本征模式和哈特曼本征模式的实时模式复原算法及其优化技术。其基本思想是把湍流畸变波前分解为一系列正校解耦的、空间特性各不相同的模式,然后根据自适应光学系统对这些模式的不同影响,以及大气湍流、噪声等工作环境对这些模式的不同影响程度,对各阶模式进行合理筛选,把系统的空间校正能力调整到最佳状态。在控制算法优化方面,本文从控制理论的角度分析了自适应光学系统的时间响应特性,研究了自适应光学系统的最优控制技术。在经典控制理论中,最优控制体现为系统的最优控制带宽或是最优控制增益。本文从理论上推导了确定系统最优控制带宽的方法,并讨论了经典控制算法下实现最优控制的局限性。在此基础上,本文提出了了一种适合在实际自适应光学系统上应用的自适应控制算法。自适应控制算法具有自动调整控制参数以适应工作环境变化的能力,可以从根本上解决自适应光学系统的最优控制问题。另外,本文还提出了一种双系统串联工作方式,讨论了这种串联工作方式提高自适应光学系统时间域校正能力的可能性。为实现自适应光学系统时间域和空间域的全面优化,本文把自适应光学系统的空间域优化技术即模式复原算法与时间域优化技术即自适应控制算法结合起来,得到了一套模式优化技术。具体做法是选通过模式复原算法对各阶波前模式进行了优化选择,调整系统的空间响应特性,然后对各个正交模式分别进行自适应控制,调整系统的时间响应特性。模式优化技术的最终目的是提高自适应光学系统的通用性、灵活性和有效性,使自适应光学系统在不同应用背景和工作环境上均达到最佳校正效果。在实验验证方面,本文研究了模式复原算法和自适应控制算法在实际自适应光学系统上的实现问题。在实际三公里水平大气湍流补偿实验中,对直接斜率法、Zernike模式法、K-L模式法、变形镜本征模法、哈特曼本征模法等各种实时复原算法的校正效果进行了对比研究。本文利用模式优化技术,得到了比目前常用复原算法和控制算法更好的实际校正效果,获得了一批国内外未见报道的实验结果。实验结果验证了本文理论分析结果和研究方法的正确性。
英文摘要: The adaptive optics (AO) system compensates the disturbed wavefront in real time. By the AO technology, traditional optical systems can hold the optimal work conditions with changing of environment. The compensation effect of an AO system limited by the time-domain and space-domain characteristics of disturbed wavefront and the AO system itself. The need of seeking for the optimal match between disturbed wavefront and the AO system is one of the most important problems in the developing of the AO technology and the design of a practical AO system. The reconstruction algorithm and the control algorithm can affect the space-domain and time-domain performances of an AO system to some degree. If we want the AO system be optimal in any work conditions, we must optimize the space-domain and time-domain performance of an AO system respectively. In order words, we should optimize the reconstruction algorithm and control algorithm respectively. Appropriate algorithms can enhance the adaptability of an AO system, discover the potentials of the system, and improve the performances of the system. In this paper, the spatial characteristic of atmosphere disturbed wavefront was analyzed by Zernike polynomials and Karhunen-Loeve (K-L) functions. The Deformable Mirror Eigen Mode (DMEM) and the Hartmann Sensor Eigen Mode (HSEM) that was a new concept introduced by the paper firstly, were used to analyze the spatial characteristic of deformable mirror, Harmann sensor and the whole AO system. The real-time model reconstruction algorithms based on Zernike polynomials, K-L functions, DMEMs and HSEMs were established and optimized in this paper too. In detail, the atmosphere disturbed wavefront was decomposed into a series of orthonormal modes with difference spatial characteristics. Then the modes were filtered based on the difference response to AO system and to the work conditions such as turbulence and measurement noise. The spatial performance of the AO system will be better after mode filtering. The time-domain characteristics of AO system and the problem of optimal control were analyzed by control theory in this paper. In traditional control theory, the concept of optimal control means the optimization of control bandwidths or controller gain. The formulas of calculating the optimal control bandwidths of an AO system were deduced. The difficulties of optimal control in traditional theory were discussed. An adaptive control algorithm that can be applied in practical AO system was given.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.ioe.ac.cn/handle/181551/35
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:
李新阳. 自适应光学系统模式复原算法和控制算法的优化研究[D]. 中国科学院光电技术研究所. 中国科学院光电技术研究所. 2000.
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