CaltechAUTHORS
  A Caltech Library Service

Strategies to cope with sodium layer profile variations in laser guide star AO systems

Ellerbroek, Brent L. (2014) Strategies to cope with sodium layer profile variations in laser guide star AO systems. In: Adaptive Optics Systems IV. Proceedings of SPIE. No.9148. Society of Photo-optical Instrumentation Engineers (SPIE) , Bellingham, WA, Art. No. 91482A. http://resolver.caltech.edu/CaltechAUTHORS:20180619-152637378

[img] PDF - Published Version
See Usage Policy.

753Kb

Use this Persistent URL to link to this item: http://resolver.caltech.edu/CaltechAUTHORS:20180619-152637378

Abstract

The vertical profile of the mesospheric sodium layer varies significantly on a time scale of one minute. These variations can impact the random and systematic measurement errors of laser guide star Shack-Hartmann wave front sensors, particularly on extremely large telescopes. Sensor performance can be improved by selecting pixel processing weights matched to the sodium layer profile, assuming that the shape of the profile can be measured or estimated in real time. In this paper we describe the magnitude of these effects for the Thirty Meter Telescope AO system NFIRAOS. We review several existing approaches for measuring or estimating the sodium layer profile in real time. We then describe a new method for estimating the profile directly from the laser guide star wave front pixel intensities themselves, jointly with the subaperture tip/tilt measurements. The algorithm used for this purpose is based upon the multi-frame iterative blind deconvolution algorithm from image post processing: Subaperture tip/tilts and the sodium profile are estimated successively, bootstrapping the estimate of each quantity from the previous estimate of the other. We present promising initial simulation results on the potential performance of the algorithm, and suggest areas for future work.


Item Type:Book Section
Related URLs:
URLURL TypeDescription
https://doi.org/10.1117/12.2054415DOIArticle
Additional Information:© 2014 Society of Photo-optical Instrumentation Engineers (SPIE). Angel Otarola provided the sample sodium layer measurements from the LZT Lidar facility. Lianqi Wang provided the simulated NFIRAOS LGS WFS pixel intensities used in Sec. 7. The TMT Project gratefully acknowledges the support of the TMT partner institutions. They are the Association of Canadian Universities for Research in Astronomy (ACURA), the California Institute of Technology, the University of California, the National Astronomical Observatory of Japan, the National Astronomical Observatories of China and their consortium partners, and the Department of Science and Technology of India and their supported institutes. This work was supported as well by the Gordon and Betty Moore Foundation, the Canada Foundation for Innovation, the Ontario Ministry of Research and Innovation, the National Research Council of Canada, the Natural Sciences and Engineering Research Council of Canada, the British Columbia Knowledge Development Fund, the Association of Universities for Research in Astronomy (AURA), and the U.S. National Science Foundation.
Group:Thirty Meter Telescope
Funders:
Funding AgencyGrant Number
Association of Canadian Universities for Research in Astronomy (ACURA)UNSPECIFIED
CaltechUNSPECIFIED
University of CaliforniaUNSPECIFIED
National Astronomical Observatory of JapanUNSPECIFIED
National Astronomical Observatories of ChinaUNSPECIFIED
Department of Science and Technology (India)UNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Canada Foundation for InnovationUNSPECIFIED
Ontario Ministry of Research and InnovationUNSPECIFIED
National Research Council of CanadaUNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
British Columbia Knowledge Development FundUNSPECIFIED
Association of Universities for Research in Astronomy (AURA)UNSPECIFIED
NSFUNSPECIFIED
Subject Keywords:Adaptive optics, laser guide stars, wave front sensing
Record Number:CaltechAUTHORS:20180619-152637378
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20180619-152637378
Official Citation:Brent L. Ellerbroek, "Strategies to cope with sodium layer profile variations in laser guide star AO systems", Proc. SPIE 9148, Adaptive Optics Systems IV, 91482A (21 July 2014); doi: 10.1117/12.2054415; https://doi.org/10.1117/12.2054415
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:87239
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:19 Jun 2018 22:48
Last Modified:19 Jun 2018 22:48

Repository Staff Only: item control page