Briguglio Runa, Quirós-Pacheco Fernando, Males Jared R, Xompero Marco, Riccardi Armando, Close Laird M, Morzinski Katie M, Esposito Simone, Pinna Enrico, Puglisi Alfio, Schatz Lauren, Miller Kelsey
INAF Osservatorio Astrofisico di Arcetri, L. E. Fermi 5, 50125, Firenze, Italy.
GMTO, 465 N. Halstead St., Suite 250, Pasadena, CA, 91107, USA.
Sci Rep. 2018 Jul 17;8(1):10835. doi: 10.1038/s41598-018-29171-6.
In this paper we describe the procedure for the optical calibration of large size deformable mirrors, acting as wavefront correctors for adaptive optics systems. Adaptive optics compensate the disturbance due to the atmospheric turbulence to restore the telescope resolution. We will showcase in particular the activities performed for the Adaptive Secondary Mirror (ASM) of the Magellan Adaptive Optics system (MagAO), which is an instrument for the 6.5 m Magellan Clay Telescope, located at Las Campanas Observatory, in Chile. The MagAO ASM calibration is part of the MagAO-2K project, a major MagAO upgrade that started in 2016 with the goal of boosting adaptive optics (AO) correction at visible wavelengths to image exoplanets. For the first time, the optical quality of MagAO mirror is reported. We describe the procedures developed to achieve high SNR interferometric measurements of the ASM modes under the presence of dome convection noise and telescope vibrations. These measurements were required to produce an improved control matrix with up to 500 modes to close the AO loop on sky with enhanced performances. An updated slaving algorithm was developed to improve the control of actuators vignetted by the central obscuration. The calibrations yielded also a new ASM flattening command, updating the one in use since the MagAO commissioning in 2013. With the new flattening command, a 22 nm RMS surface error was achieved. Finally, we present on-sky results showing the MagAO performance achieved with the new calibrations.
在本文中，我们描述了用于大尺寸变形镜光学校准的程序，这种变形镜用作自适应光学系统的波前校正器。自适应光学可补偿大气湍流引起的干扰，以恢复望远镜的分辨率。我们将特别展示为麦哲伦自适应光学系统（MagAO）的自适应副镜（ASM）所开展的工作，该系统是位于智利拉斯坎帕纳斯天文台的6.5米麦哲伦·克莱望远镜的一种仪器。MagAO ASM校准是MagAO - 2K项目的一部分，这是MagAO的一次重大升级，该项目于2016年启动，目标是在可见光波长下增强自适应光学（AO）校正以对系外行星成像。首次报告了MagAO镜的光学质量。我们描述了在圆顶对流噪声和望远镜振动存在的情况下，为实现对ASM模式进行高信噪比干涉测量而开发的程序。这些测量对于生成一个改进的控制矩阵是必要的，该矩阵具有多达500个模式，以便在天空中以增强的性能闭合AO回路。开发了一种更新的从属算法，以改进对因中央遮挡而渐晕的致动器的控制。校准还产生了一个新的ASM平坦化指令，更新了自2013年MagAO调试以来一直在使用的指令。通过新的平坦化指令，实现了22纳米的均方根表面误差。最后，我们展示了在天空中使用新校准所实现的MagAO性能的结果。
