Xin Bo, Claver Chuck, Liang Ming, Chandrasekharan Srinivasan, Angeli George, Shipsey Ian
Appl Opt. 2015 Oct 20;54(30):9045-54. doi: 10.1364/AO.54.009045.
The Large Synoptic Survey Telescope (LSST) will use an active optics system (AOS) to maintain alignment and surface figure on its three large mirrors. Corrective actions fed to the LSST AOS are determined from information derived from four curvature wavefront sensors located at the corners of the focal plane. Each wavefront sensor is a split detector such that the halves are 1 mm on either side of focus. In this paper, we describe the extensions to published curvature wavefront sensing algorithms needed to address challenges presented by the LSST, namely the large central obscuration, the fast f/1.23 beam, off-axis pupil distortions, and vignetting at the sensor locations. We also describe corrections needed for the split sensors and the effects from the angular separation of different stars providing the intrafocal and extrafocal images. Lastly, we present simulations that demonstrate convergence, linearity, and negligible noise when compared to atmospheric effects when the algorithm extensions are applied to the LSST optical system. The algorithm extensions reported here are generic and can easily be adapted to other wide-field optical systems including similar telescopes with large central obscuration and off-axis curvature sensing.
大型综合巡天望远镜（LSST）将使用主动光学系统（AOS）来保持其三块大型镜子的对准和表面形状。反馈给LSST AOS的校正动作是根据从位于焦平面角落的四个曲率波前传感器获取的信息确定的。每个波前传感器都是一个分裂探测器，其两半在焦点两侧各为1毫米。在本文中，我们描述了对已发表的曲率波前传感算法的扩展，以应对LSST所带来的挑战，即大的中心遮挡、快速的f/1.23光束、离轴光瞳畸变以及传感器位置处的渐晕。我们还描述了分裂传感器所需的校正以及提供焦内和焦外图像的不同恒星角间距的影响。最后，我们给出了模拟结果，当将算法扩展应用于LSST光学系统时，与大气效应相比，这些模拟结果展示了收敛性、线性度以及可忽略的噪声。这里报告的算法扩展是通用的，并且可以很容易地适用于其他宽视场光学系统，包括具有大中心遮挡和离轴曲率传感的类似望远镜。
