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Proceedings Paper

Real time wavefront control system for the Large Synoptic Survey Telescope (LSST)
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Paper Abstract

The LSST is an integrated, ground based survey system designed to conduct a decade-long time domain survey of the optical sky. It consists of an 8-meter class wide-field telescope, a 3.2 Gpixel camera, and an automated data processing system. In order to realize the scientific potential of the LSST, its optical system has to provide excellent and consistent image quality across the entire 3.5 degree Field of View. The purpose of the Active Optics System (AOS) is to optimize the image quality by controlling the surface figures of the telescope mirrors and maintaining the relative positions of the optical elements. The basic challenge of the wavefront sensor feedback loop for an LSST type 3-mirror telescope is the near degeneracy of the influence function linking optical degrees of freedom to the measured wavefront errors. Our approach to mitigate this problem is modal control, where a limited number of modes (combinations of optical degrees of freedom) are operated at the sampling rate of the wavefront sensing, while the control bandwidth for the barely observable modes is significantly lower. The paper presents a control strategy based on linear approximations to the system, and the verification of this strategy against system requirements by simulations using more complete, non-linear models for LSST optics and the curvature wavefront sensors.

Paper Details

Date Published: 4 August 2014
PDF: 16 pages
Proc. SPIE 9150, Modeling, Systems Engineering, and Project Management for Astronomy VI, 91500H (4 August 2014); doi: 10.1117/12.2055390
Show Author Affiliations
George Z. Angeli, LSST Corp. (United States)
Bo Xin, LSST Corp. (United States)
Charles Claver, LSST Corp. (United States)
Douglas MacMartin, California Institute of Technology (United States)
Douglas Neill, LSST Corp. (United States)
Matthew Britton, the Optical Sciences Co. (United States)
Jacques Sebag, LSST Corp. (United States)
Srinivasan Chandrasekharan, LSST Corp. (United States)

Published in SPIE Proceedings Vol. 9150:
Modeling, Systems Engineering, and Project Management for Astronomy VI
George Z. Angeli; Philippe Dierickx, Editor(s)

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