介绍了随机并行梯度下降(SPGD)算法及其在相干合成中的应用，针对实验中算法关键参数难以调节的难点，提出采用软硬件结合的新方式，实现对实验数据的在线采集和分析以及对SPGD算法关键参数的自动实时调节。开展了4路光纤激光相干合成实验，对不同调节方法进行对比。实验中采用新方式有效调节了SPGD算法中增益系数和随机扰动幅度的取值，合成效果显著。

To obtain a large-aperture high damage threshold grating compressor for a perawatt laser system, the multi-piece dielectric membrane tiled grating is an effective method. In order to avoid the influence of tiling error on the temporal and spatial characteristics of grating, the rotation error needs to be controlled in 1 μrad. Therefore, the zero-order and first-order diffracting light is used to monitor the rotation error independently. 0.1 pixel accuracy can be achieved by location of the center of fringe with quadratic curve-fitting, which can detect rotation error about 0.5 μrad. For the requirement of high precision is confined by the controlling device and environment, real-time monitoring and adjusting are necessary to maintain the grating posture, and feedback the deflection to the installations to maintain the sub-grating position. The deviation can be maintained within 0.5 μrad for a long time. Experiments show the rotation error real-time monitoring and adjusting about tiled gratings can meet precision and stability requirements.

为了获得拍瓦激光系统需要的大口径高破坏阈值光栅压缩器,用多块电介质膜光栅进行拼接是解决问题的有效方法。旋转偏差需要控制在1 μrad内,才能避免拼接误差带来的时空特性影响,因此利用零级光和一级衍射光对旋转偏差进行独立监测,采用二次曲线拟合法对干涉条纹中心位置进行高精度测量,测量精度可达0.1 pixel,检测到旋转偏差约0.5 μrad;高精度的要求受调节机构和环境的限制,需实时监测调节来保持光栅姿态,将偏转量反馈给光栅调节装置保持拼接子光栅的位置,可长时间保持在0.5 μrad偏差内。实验结果表明,光栅拼接旋转偏差实时监测调节能满足拼接高精度和长时间稳定的要求。