Béchet Clémentine, Tallon Michel, Tallon-Bosc Isabelle, Thiébaut Éric, Le Louarn Miska, Clare Richard M
European Southern Observatory (ESO), Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany.
J Opt Soc Am A Opt Image Sci Vis. 2010 Nov 1;27(11):A1-8. doi: 10.1364/JOSAA.27.0000A1.
The design of the laser-guide-star-based adaptive optics (AO) systems for the Extremely Large Telescopes requires careful study of the issue of elongated spots produced on Shack-Hartmann wavefront sensors. The importance of a correct modeling of the nonuniformity and correlations of the noise induced by this elongation has already been demonstrated for wavefront reconstruction. We report here on the first (to our knowledge) end-to-end simulations of closed-loop ground-layer AO with laser guide stars with such an improved noise model. The results are compared with the level of performance predicted by a classical noise model for the reconstruction. The performance is studied in terms of ensquared energy and confirms that, thanks to the improved noise model, central or side launching of the lasers does not affect the performance with respect to the laser guide stars' flux. These two launching schemes also perform similarly whatever the atmospheric turbulence strength.
为极大望远镜设计基于激光导星的自适应光学（AO）系统，需要仔细研究在夏克 - 哈特曼波前传感器上产生的拉长光斑问题。对于波前重建而言，正确建模由这种拉长所引起的噪声的不均匀性和相关性的重要性已得到证明。在此，我们报告（据我们所知）首次使用这种改进噪声模型对带有激光导星的闭环地面层AO进行的端到端模拟。将结果与用于重建的经典噪声模型预测的性能水平进行比较。从环围能量的角度研究性能，并证实由于改进的噪声模型，激光的中心发射或侧面发射在激光导星通量方面不会影响性能。无论大气湍流强度如何，这两种发射方案的性能也相似。
