中国激光, 2014, 41 (6): 0612002, 网络出版: 2014-04-16
信标湍流探测中波前非等晕问题的研究I数值建模
Investigation of Anisoplanatic Effect in Atmospheric Turbulence Probing with Beacon INumerical Modeling
大气光学 自适应光学 信标 非等晕误差 数值建模 atmospheric optics adaptive optics guide star anisoplanatic error numerical modeling
摘要
信标概念的提出解决了自适应光学(AO)系统的湍流参考源问题,同时也带来了不可避免的非等晕误差。综合考虑实际中信标与观测目标之间的空间角度与高度差异,利用数值建模对不同信标机制下(包括自然信标、人造信标)湍流探测中波前像差模式的非等晕性误差进行了系统性分析。研究发现:自然信标机制下,有效的纯角度非等晕性方差较传统评估值(θ/θ0)5/3偏小;因而,传统评估方式中直接利用大气等晕角θ0评估纯角度非等晕性误差对AO校正的影响,比实际影响严重。人造信标机制下,无角度偏差时的模式非等晕性误差随信标高度增加而减小;但由于角度偏差所致信标探测波前与待校正目标波前之间模式相关性的退化,却随信标高度增加而变得更加敏感,此时应根据应用需求对AO系统工作模式与信标模式进行权衡优化选择。研究所得的理论结果为外大气信标自适应光学实验的展开提供了必要的理论支持。
Abstract
The atmospheric turbulence probing source of adaptive optics (AO) is proposed by the promotion of beacon (namely guide star, GS). However the unavoidable anisoplanatic error it brings can degrade the performance of AO system. Taking account of the differences of height location and spatial angular deviations between GS and object, the ensemble statistical characteristics of anisoplanatic error with different GS modes are investigated by numerical modeling, including natural guide star (NGS) and laser guide star (LGS). In NGS mode, the effective angular anisoplanatic variance is smaller than the traditional evaluation value (θ/θ0)5/3. So the conventional characterization of the angular anisoplanatic degradation in AO correction with atmospheric anisoplanatic angle θ0 is more serious than actual circumstance. In LGS mode, the higher the beacon probing altitude is, the smaller the Zernike aberration modal anisoplanatic error is. But the aberration modal correlation degradation between LGS and object resulted from their angular deviation becomes more sensitive. Under such circumstance the AO system operation mode and the GS mode should be weighed up and optimized according to practical application. The numerical results provide theoretical support for the experiment investigation of atmospheric AO with LGS in future.
罗曦, 李新阳. 信标湍流探测中波前非等晕问题的研究I数值建模[J]. 中国激光, 2014, 41(6): 0612002. Luo Xi, Li Xinyang. Investigation of Anisoplanatic Effect in Atmospheric Turbulence Probing with Beacon INumerical Modeling[J]. Chinese Journal of Lasers, 2014, 41(6): 0612002.