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

George Z. Angeli; Bo Xin; Charles Claver; Douglas MacMartin; Douglas Neill; Matthew Britton; Jacques Sebag; Srinivasan Chandrasekharan

doi:10.1117/12.2055390

4 August 2014 Real time wavefront control system for the Large Synoptic Survey Telescope (LSST)

George Z. Angeli, Bo Xin, Charles Claver, Douglas MacMartin, Douglas Neill, Matthew Britton, Jacques Sebag, Srinivasan Chandrasekharan

Author Affiliations +

Proceedings Volume 9150, Modeling, Systems Engineering, and Project Management for Astronomy VI; 91500H (2014) https://doi.org/10.1117/12.2055390
Event: SPIE Astronomical Telescopes + Instrumentation, 2014, Montréal, Quebec, Canada

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.

Citation Download Citation

George Z. Angeli, Bo Xin, Charles Claver, Douglas MacMartin, Douglas Neill, Matthew Britton, Jacques Sebag, and Srinivasan Chandrasekharan "Real time wavefront control system for the Large Synoptic Survey Telescope (LSST)", Proc. SPIE 9150, Modeling, Systems Engineering, and Project Management for Astronomy VI, 91500H (4 August 2014); https://doi.org/10.1117/12.2055390

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