针对随机并行梯度下降(SPGD)算法实时性强,同时具有一定的灵活性的要求,本文提出了一种基于FPGA的SPGD 算法硬件实现方法。该方法首先划分了各功能模块,然后对关键模块进行了实时化处理,并使用“流水线”和RAM 技术设计了可升级和扩展的变形镜控制模块。最后将该算法实现并应用到61 单元自适应光学激光实验中,结果表明本文的设计可使用不同的性能指标实现变形镜的SPGD 算法闭环控制,并能同时完成倾斜镜的控制,达到了实时性和灵活性的要求。

To meet the request of real-time control and the flexility of the Stochastic Parallel Gradient Descent (SPGD) algorithm for Adaptive Optics (AO) system, an implementation of the SPGD algorithm in FPGA was proposed. Firstly, the diagram of the SPGD algorithm controlling system was designed. Then, the key modules were processed for real-time control, and a deformable-mirror controlling module that can be updated for future application was designed according to the pipeline and RAM techniques. Based on this implementation, a laser beam focusing system with a 61-element deformable mirror and high frame-frequency CCD was built. The experimental results demonstrate that the AO system can correct static distorted wave-front successfully with different system performance metrics and can also control deformable mirror and tilt mirror simultaneously.