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Shack-Hartmann wavefront sensing with elongated sodium laser beacons: centroiding versus matched filtering

Gilles, Luc and Ellerbroek, Brent (2006) Shack-Hartmann wavefront sensing with elongated sodium laser beacons: centroiding versus matched filtering. Applied Optics, 45 (25). pp. 6568-6576. ISSN 0003-6935.

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We describe modeling and simulation results for the Thirty Meter Telescope on the degradation of sodium laser guide star Shack-Hartmann wavefront sensor measurement accuracy that will occur due to the spatial structure and temporal variations of the mesospheric sodium layer. By using a contiguous set of lidar measurements of the sodium profile, the performance of a standard centroid and of a more refined noise-optimal matched filter spot position estimation algorithm is analyzed and compared for a nominal mean signal level equal to 1000 photodetected electrons per subaperture per integration time, as a function of subaperture to laser launch telescope distance and CCD pixel readout noise. Both algorithms are compared in terms of their rms spot position estimation error due to noise, their associated wavefront error when implemented on the Thirty Meter Telescope facility adaptive optics system, their linear dynamic range, and their bias when detuned from the current sodium profile.

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Additional Information:© 2006 Optical Society of America Received 21 November 2005; accepted 10 April 2006; posted 17 April 2006 (Doc. ID 65931). The authors thank the Purple Crow Lidar team from the University of Western Ontaria, Canada, for making their sodium layer measurements available to us. The authors also thank Glen Herriot and Jean-Pierre Véran from the Herzberg Institute of Astronomy, Canada, for fruitful discussions. The authors acknowledge the support of the TMT partner institutions including the Association of Canadian Universities for Research in Astronomy (ACURA), the Association of Universities for Research in Astronomy (AURA), the California Institute of Technology, and the University of California. This work was also supported by the Canada Foundation for Innovation, the Gordon and Betty Moore Foundation, the National Optical Astronomy Observatory, which is operated by AURA under cooperative agreement with the National Science Foundation, the Ontario Ministry of Research and Innovation, and the National Research Council of Canada.
Subject Keywords:Adaptive optics; Wave-front sensing
Issue or Number:25
Record Number:CaltechAUTHORS:GILao06
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:5158
Deposited By: Archive Administrator
Deposited On:03 Oct 2006
Last Modified:02 Oct 2019 23:19

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