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题名:
自适应光学系统SPGD控制算法的FPGA实现及实验研究
作者: 张金宝
学位类别: 硕士
答辩日期: 2009-06-02
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: 李新阳
关键词: 自适应光学 ; SPGD算法 ; FPGA
其他题名: FPGA Implementation and Experimental Demonstration of Stochastic Parallel Gradient Descent Control Algorithm for Adaptive Optics System
学位专业: 计算机应用技术
中文摘要:   SPGD控制算法(随机并行梯度下降,Stochastic Parallel Gradient Descent algorithm)是一种无波前探测自适应光学技术。与常规自适应光学技术相比,该方法不需要进行波前测量和波前重构,而是把波前校正器的控制信号作为优化参数,以应用系统所关心的系统性能指标直接作为优化算法的目标函数,通过寻优得到接近理想的校正效果。由于不再需要波前探测,一方面简化了系统结构,另一方面拓展了常规自适应光学技术在波前无法测量环境中的应用。   作为寻优控制的方法,算法的迭代速度对控制带宽起着相当关键的作用。而算法的实现方式对迭代速度有着决定性的影响,因此算法的实现方式至关重要。本文在研究现有SPGD算法实现方式的基础上,提出了基于FPGA平台的硬件电路实现方法。该设计能够同时控制倾斜镜和61单元的变形镜,具有近千次每秒的算法迭代速度。   利用该算法实现平台,搭建了61单元SPGD算法自适应光学实验系统,分别开展了静态和动态波前畸变校正实验。通过静态波前畸变校正实验表明该实验系统对静态波前畸变具有良好的校正效果。在动态波前畸变实验中,分别使用热风式湍流模拟装置和转动位相板产生动态波前扰动。动态波前畸变校正实验结果表明该实验系统的有效带宽约为10Hz。
英文摘要:  The stochastic parallel gradient descent (SPGD) algorithm is an adaptive optics (AO) control technique without wave-front sensor. Compared with the conventional AO control methods, this AO control technique doesn’t need to measure the wave-front and reconstruct it, but considers the performance metric as a function of the control parameters and then uses SPGD optimization algorithm to improve the performance metrics. It is simpler than the conventional AO in system architecture and can be applied to the complicated conditions where wave-front distortions can not be measured directly.  In order to put the SPGD algorithm into practical use, fast iteration speed is necessary. Based on the study of two existing implementations of the SPGD algorithm, we proposed a new way of implementing it in FPGA. Composed of hardware circuits, the FPGA can work at very high speed and guarantee the real-time control of the AO system. On the other hand, the FPGA is programmable, thus makes it flexible to modify the implementation when needed. The hardware implementation that can control a 61-element deformable mirror in AO system was designed in our research.  A laser beam focusing AO system was then built and two kinds of wave-front distortions were considered in our experiment. First static distortions are induced by the AO system itself and phase-aberration-plate. Then dynamic distortions are induced by heater and rotating phase-plate. The static distortion-correction-experiment demonstrates that our FPGA implementation of SPGD algorithm can work successfully. The factors that influence the convergence rate and effect are also discussed in this experiment. The dynamic distortion-correction-experiment shows that our AO system can improve the laser beam quality in the spectral band up to 10Hz.
语种: 中文
内容类型: 学位论文
URI标识: http://ir.ioe.ac.cn/handle/181551/384
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:
张金宝. 自适应光学系统SPGD控制算法的FPGA实现及实验研究[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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