激光导引星大气湍流波前非等晕性误差的像差模式分解

Modal Decomposition of Anisoplanatic Error of Atmospheric Turbulence for a Laser Guide Star

激光导引星概念解决了自适应光学技术的信标问题 ,同时带来了无法克服的非等晕性误差。将高度聚焦非等晕性误差和角度非等晕性误差统一起来考虑 ,分析激光导引星的大气湍流波前各阶模式的非等晕性误差 ,并给出了解析模型。同时分析了瑞利导星和钠导星的大气湍流波前的模式非等晕性相对误差 ,在没有角度偏离的情况下 ,90km的钠导星的模式非等晕性误差明显小于 15km的瑞利导星 ,但是它对角度的敏感程度却远远大于瑞利导星。采用激光导引星的自适应光学系统用于大气湍流的校正 ,选择较低阶的模式校正就可以达到较好的效果 ,而且即使目标与导引星的偏角大于等晕角 。

The beacon problem of adaptive optics (AO) is settled by the promotion of laser guide star (LGS), but the anisoplanatic error due to LGS will degrade the performance of AO system as well. Analytical expressions are given to evaluate the modal anisoplanatic error of atmospheric turbulence for LGS. Anisoplanatic error for Rayleigh LGS and Na LGS are also analyzed. Results show that the modal anisoplanatic error of 90 km Na LGS is obviously less than that of 15 km Rayleigh LGS without the angle deviation between LGS and object, but is greatly sensitive to the angle deviation than Rayleigh LGS. Good performance will be obtained with low order aberration mode correction in LGS AOS, and when angle deviation between beacon and object is larger than isoplanatic patch, low order modes should be corrected for effective correcting result.