高能激光系统中通常包含光束净化装置以对激光器出射光束的波前畸变进行连续校正。为研究随机并行梯度下降自适应光学方法在光束净化问题上的可行性, 按算法运行时序连续改变37单元变形镜的面形, 以在实验光路中引入高能激光器输出光束的常见动态波前畸变, 同时采用随机并行梯度下降算法控制同一变形镜对此动态畸变进行校正。实验结果显示, 在事先消除系统初始像差的情况下, 系统分别以1 kHz和2 kHz的模拟迭代速率工作时, 激光束的动态像差都得到了充分抑制, 光束质量在整个校正时段内始终维持在较好水平。这表明随机并行梯度下降自适应光学方法应用在光束净化系统中是可行的。

A beam cleanup subsystem is usually contained in high power laser system to correct for the wavefront aberrations of the output beam of the laser resonator continuously. To investigate the feasibility of the stochastic parallel gradient descent (SPGD) adaptive optics method on beam cleanup issue, dynamical wavefront aberrations, analogous to the commonly encountered wavefront distortions in high power laser beams, are first introduced into the experimental laser beam by continuously changing the surface shape of a 37-element deformable mirror incorporated in the system according to the iteration sequence of the SPGD algorithm, and then the same deformable mirror is used to correct for the produced aberrations by applying the SPGD algorithm to upgrade the control voltages of the mirror actuators. The experimental results show that, when the initial aberrations of the system being removed, the dynamic wavefront aberrations of the laser beam can be compensated successfully and the beam quality remains on a high level during the whole correction period with the system working on simulated iteration rates of 1 kHz and 2 kHz respectively. It is indicated that the SPGD adaptive optics method is feasible on beam cleanup system.