中国激光, 2014, 41 (6): 0602002, 网络出版: 2014-04-09
相干合成中基于SPGD算法的平移误差和倾斜误差控制
Error Control of Piston and Tilt Based on SPGD in Coherent Beam Combination
激光光学 随机并行梯度下降算法 平移误差 倾斜误差 相干合成 短脉冲激光 laser optics stochastic parallel gradient descent pistion error tilt error coherent beam combination short-pulse laser
摘要
随机并行梯度下降算法(SPGD)是控制多路激光束的相位锁定,实现相干合成的一种有效方式。在分析平移误差和倾斜误差对相干合成(CBC)影响的基础上,建立2×2排布的光束模型探讨了该算法中的增益系数和扰动幅值对平移误差和倾斜误差控制的影响,并对增益系数的优化进行了分析。研究结果表明,要提高相干合成的效果,必须同时校正平移误差和倾斜误差;随着增益系数和扰动幅值的增加,SPGD算法的收敛速度加快,但计算精度降低,系统会发生振荡;自适应更新增益系数是一种有效的参数优化方式,可很好平衡算法收敛速度和计算精度问题。为大型固体短脉冲激光装置中基于SPGD算法进行相干合成研究提供了理论参考。
Abstract
Stochastic parallel gradient descent (SPGD) is an effective way to achieve multi-channel phase-locked laser beams for coherent beam combination (CBC). In this paper, the influence of piston error and tilt error on CBC is primarily presented. Then, an arrangement model of 2×2 laser beams is built. With this proposed model, SPGD is tested and verified. Key parameters, the gain coefficient and the disturbance amplitude, impacts on the error control performance of the algorithm, are analyzed and optimized. The surveys show that it is necessary to control piston error and tilt error for CBC. When SPGD is used to correct the above errors, the convergence speed of the algorithm is improved with the increase of the gain coefficient and the disturbance amplitude, however, the accuracy of SPGD is reduced and the system is vibrated. In order to improve CBC, the adaptive gain coefficient is studied. Compared with the fixed gain coefficient, the adaptive gain coefficient is able to make a good balance between the convergence speed and the accuracy of the algorithm, which indicates that the adaptive gain coefficient is an effective optimization way. These results in this paper provide a theoretical reference for CBC using SPGD in a large short-pulse laser facility.
母杰, 景峰, 王逍, 朱启华, 李志林, 张军伟. 相干合成中基于SPGD算法的平移误差和倾斜误差控制[J]. 中国激光, 2014, 41(6): 0602002. Mu Jie, Jing Feng, Wang Xiao, Zhu Qihua, Li Zhilin, Zhang Junwei. Error Control of Piston and Tilt Based on SPGD in Coherent Beam Combination[J]. Chinese Journal of Lasers, 2014, 41(6): 0602002.