大气湍流三维波前探测模式层析算法分析

Analysis of modal tomography for three-dimensional wavefront sensing of atmosphere turbulence

大气湍流三维波前探测是实现多层共轭自适应光学技术的关键和前提.对湍流三维波前探测中最常用的模式法层析技术进行理论研究与分析,提出该算法存在原理性限制,并基于此对模式法层析技术产生误差的原因展开分析,最后针对不同类型的模式层析重构误差给出数值仿真实验结果.分析表明,模式层析重构中使用了Zernike分解基的一部分作为新的分解基进行波面拟合,从而引入模式混淆和模式耦合两个方面的误差;部分Zernike分解基不相关是避免模式混淆误差的必要条件,模式耦合误差则无法避免.最后结合仿真结果提出大视场探测、小区域重构的方法,很好地抑制了模式耦合误差.

Three-dimensional （3D） wavefront sensing of atmosphere turbulence is a key step to realize multi-conjugate adaptive optics technology. In this article, model tomography, which is one of the most important algorithms for 3D wavefront sensing, is analyzed in theory, the principle limitation of model tomography is proposed. Based on this view the reason for tomography error is discussed, and the simulation results for different errors are produced finally. The analysis shows that part Zernike model basis is used as a new basis of polynomial decomposition in model tomography, which leads to modal coupling error and aliasing error. The un-correlation of part Zernike model basis is the prerequisite to avoid modal aliasing error, but modal coupling error cannot be removed and we can only restrain its influence. Combined with simulation result a method with large field of view （FOV） sensing and small FOV reconstruction is proposed and gives a good performance to control modal coupling error.