振幅非均匀波前的相位畸变传感及自适应校正技术研究

The technology of adaptive optics is widely applied in the fields of astronomical observation, laser-beam control and medical diagnose. In an practical system, when then intensity of source for wavefront detection is too weak or the amplitude of wavefront is non-uniform, the detection accuracy of wavefront sensor will drop seriously. It will affect the correction efficiency of the whole adaptive optics system. This project is put forward from the “imperfect” condition, studying on the phase sensing of non-uniform amplitude wavefront and its correction technology, to solve the problem of “blind” wavefront sensor in several typical systems. (1) An aberration detection method based on two Shack-Hartmann sensors is brought forward. It helps to find the relationship between the deflection of spots and the characteristic parameters of the aberration.(2) Based on the distribution characteristics of the aberration, the center of the “lost” spots is estimated. (3) The algorithm of the data fusion of two Shack-Hartmann wavefront sensors is studied. And the direct gradient algorithm for close-loop adaptive correction is analyzed, too. The experiments are set up to verify the efficiency of the algorithm. The conclusions of this project will improve the adaptability of the technology of the adaptive optics and promote it to a wider and deeper application.

自适应光学技术被广泛应用于天文观测、激光光束控制和医疗诊断等领域。在实际系统中，当波前探测所利用的光源较微弱或振幅分布不均匀时，波前传感器的实际测量精度相对于设计精度大打折扣，也严重影响到整个自适应光学系统的波前校正效率。本项目从“非理想”的应用环境出发，研究振幅非均匀波前的相位畸变传感和自适应校正技术，解决几种典型应用中波前传感器“看不准”或“误看”问题：（1）提出基于双哈特曼探测技术的畸变源扰动时空特性测量方法，揭示子孔径光斑偏转特性与畸变源扰动特征参量的内在关联；（2）基于畸变源扰动时空变化特性，对传感器“缺失”光斑的质心位置作出实时、最优估计；（3）研究多哈特曼数据融合算法，以及基于数据融合算法的自适应直接斜率闭环控制算法，实验验证算法的有效性和执行效率。研究结果将进一步提升自适应光学技术对复杂环境的适应性，推动自适应光学向更广、更深发展。

本项目从“非理想”的应用环境出发，研究了振幅非均匀波前的相位畸变传感和自适应校正技术，基本解决了几种典型应用中波前传感器“看不准”或“误看”问题：（1）提出了一种新的基于双哈特曼数据融合技术的分光镜热畸变实时校正方法。给出了数据融合理论模型，详细讨论了影响数据融合算法效率的各种因素，如入射光束角度、激光波长差异和空间分辨率失配等问题。建立了包括常规自适应光学系统和双哈特曼探测器在内的实验系统，验证数据融合算法的有效性。实验结果表明，该系统可以实时校正氟化钙分光镜的热畸变。系统输出光束质量因子从4倍衍射极限降低至1.7倍，光束质量明显提高。此外，实验研究结果与理论模拟结果符合较好。（2）基于畸变源扰动时空变化特性，对传感器“缺失”光斑的质心位置作出实时、最优估计；（3）研究了多哈特曼数据融合算法，以及基于数据融合算法的自适应直接斜率闭环控制算法，实验验证了算法的有效性和执行效率。