Sensing and control of segmented mirrors with a pyramid wavefront sensor in the presence of spiders
Sensing and control of segmented mirrors with a pyramid wavefront sensor in the presence of spiders
复制标题
在蜘蛛存在的情况下使用金字塔波前传感器感测和控制分段镜
DOI：
10.26698/ao4elt5.0015
复制
发表时间：
2018
期刊：
影响因子：
--
通讯作者：
J. Vernet
中科院分区：
文献类型：
--
作者：
N. Schwartz;J. Sauvage;C. Correia;C. Petit;F. Quirós;T. Fusco;K. Dohlen;K. E. Hadi;N. Thatte;F. Clarke;J. Paufique;J. Vernet
望远镜瞳孔的分割（通过蜘蛛和分割的M4）在波前传感器（WFS）上创建了由蜘蛛宽度隔离的相位区域，打破了波前的空间连续性。金字塔WFS（PWFS）对差动活塞的差的灵敏度导致差的可见性并且因此导致不可控的差动活塞。在闭环操作中，段之间的差动活塞将稳定在平均感测波长的整数值附近。差动活塞的范围通常为传感波长的一到十倍，并随时间迅速变化，导致性能极差。此外，由大气湍流产生的像差将包含节段之间的大量差动活塞。去除每个DM段上的活塞贡献导致性能差。为了减少不必要的差分活塞的影响，由AO校正注入，我们比较了三种不同的方法。我们首先限制自己仅使用PWFS测量的信息，特别是通过减少调制。我们表明，合理地使用这些信息是重要的，但还不够。我们讨论了可能的改进方法，通过使用先验信息。第二种方法是基于DM命令的相位闭合，并假设校正波前在整个未分割瞳孔上的连续性。最后一种方法是基于成对从动的边缘执行器，并显示出最好的结果。我们比较这些方法的性能，使用现实的端到端的模拟。我们发现，成对的奴隶导致一个小的总波前误差的增加，只增加了20-45 nm RMS之间的正交看到0.45-0.85弧秒之间的条件。最后，我们讨论了结合不同的解决方案，以提高鲁棒性的可能性。
The segmentation of the telescope pupil (by spiders & the segmented M4) create areas of phase isolated by the width of the spiders on the wavefront sensor (WFS), breaking the spatial continuity of the wavefront. The poor sensitivity of the Pyramid WFS (PWFS) to differential piston leads to badly seen and therefore uncontrollable differential pistons. In close loop operation, differential pistons between segments will settle around integer values of the average sensing wavelength. The differential pistons typically range from one to ten times the sensing wavelength and vary rapidly over time, leading to extremely poor performance. In addition, aberrations created by atmospheric turbulence will contain large amounts of differential piston between the segments. Removing piston contribution over each of the DM segments leads to poor performance. In an attempt to reduce the impact of unwanted differential pistons that are injected by the AO correction, we compare three different approaches. We first limit ourselves to only use the information measured by the PWFS, in particular by reducing the modulation. We show that using this information sensibly is important but will not be sufficient. We discuss possible ways of improvement by using prior information. A second approach is based on phase closure of the DM commands and assumes the continuity of the correction wavefront over the entire unsegmented pupil. The last approach is based on the pair-wise slaving of edge actuators and shows the best results. We compare the performance of these methods using realistic end-to-end simulations. We find that pair-wise slaving leads to a small increase of the total wavefront error, only adding between 20-45 nm RMS in quadrature for seeing conditions between 0.45-0.85 arcsec. Finally, we discuss the possibility of combining the different proposed solutions to increase robustness.
HARMONI 的自适应光学系统：E-ELT 的可见光和近红外积分场光谱仪
DOI：
10.1117/12.857507
发表时间：
2010
期刊：
--
影响因子：
--
作者：
Fusco T
通讯作者：
Fusco T