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Curvature Wavefront Sensing for the Large Synoptic Survey Telescope

Xin, Bo et al.
Claver, C.; Liang, M; Chandrasekharan, S.; Angeli, G.; Shipsey, I.
Publication Date: 
Tuesday, October 20, 2015
Journal Articles
Applied Optics
54, Issue 30
Page #: 
8 817

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 4 curvature wavefront sensors located at the corners of the focal plane. Each wavefront sensor is a split detector such that the halves are 1mm 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 intra- and extra-focal 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.

Bibtex reference: 
@ARTICLE{2015arXiv150604839X, author = {{Xin}, B. and {Claver}, C. and {Liang}, M. and {Chandrasekharan}, S. and {Angeli}, G. and {Shipsey}, I.}, title = "{Curvature Wavefront Sensing for the Large Synoptic Survey Telescope}", journal = {ArXiv e-prints}, archivePrefix = "arXiv", eprint = {1506.04839}, primaryClass = "astro-ph.IM", keywords = {Astrophysics - Instrumentation and Methods for Astrophysics}, year = 2015, month = jun, adsurl = {}, adsnote = {Provided by the SAO/NASA Astrophysics Data System}

Financial support for LSST comes from the National Science Foundation (NSF) through Cooperative Agreement No. 1258333, the Department of Energy (DOE) Office of Science under Contract No. DE-AC02-76SF00515, and private funding raised by the LSST Corporation. The NSF-funded LSST Project Office for construction was established as an operating center under management of the Association of Universities for Research in Astronomy (AURA).  The DOE-funded effort to build the LSST camera is managed by the SLAC National Accelerator Laboratory (SLAC).
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