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Impact of sodium laser guide star fratricide on multi-conjugate adaptive optics systems

Wang, Lianqi and Otarola, Angel and Ellerbroek, Brent (2010) Impact of sodium laser guide star fratricide on multi-conjugate adaptive optics systems. Journal of the Optical Society of America A, 27 (11). A19-A28. ISSN 1084-7529.

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Laser beams projected from the ground to form sodium layer laser guide stars (LGSs) for adaptive optics (AO) systems experience scattering and absorption that reduce their intensity as they propagate upward through the atmosphere. Some fraction of the scattered light will be collected by the other wavefront sensors and causes additional background in parts of the pupil. This cross-talk between different LGS wavefront sensors is referred to as the fratricide effect. In this paper we quantify the magnitude of four different sources of scattering/absorption and backscattering, and we evaluate their impact on performance with various zenith angles and turbulence profiles for one particular AO system. The resulting wavefront error for the Thirty Meter Telescope (TMT) multi-conjugate AO (MCAO) system, NFIRAOS, is on the order of 5 to 20 nm RMS, provided that the mean background from the fratricide effect can be calibrated and subtracted with an accuracy of 80%. We also present the impact on system performance of momentary variations in LGS signal levels due to variations in cirrus absorption or laser power, and we show that this affects the performance more than does an equal variation in the level of the fratricide.

Item Type:Article
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Wang, Lianqi0000-0002-9803-166X
Additional Information:© 2010 Optical Society of America. Received April 12, 2010; accepted June 1, 2010; posted June 7, 2010 (Doc. ID 126821); published June 23, 2010. This work is supported by the Thirty Meter Telescope (TMT) project. The authors gratefully acknowledge the support of the TMT partner institutions. They are the Association of Canadian Universities for Research in Astronomy (ACURA), the California Institute of Technology, and the University of California. 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 (NSERC), the British Columbia Knowledge Development Fund, the Association of Universities for Research in Astronomy (AURA), and the U.S. National Science Foundation (NSF).
Funding AgencyGrant Number
Thirty Meter Telescope (TMT) projectUNSPECIFIED
TMT partner institutionsUNSPECIFIED
Gordon and Betty Moore FoundationUNSPECIFIED
Canada Foundation for InnovationUNSPECIFIED
Ontario Ministry of Research and InnovationUNSPECIFIED
National Research Council of Canada (NRCC)UNSPECIFIED
Natural Sciences and Engineering Research Council of Canada (NSERC)UNSPECIFIED
British Columbia Knowledge Development FundUNSPECIFIED
Association of Universities for Research in Astronomy (AURA)UNSPECIFIED
Issue or Number:11
Classification Code:OCIS Codes: # (010.1080) Atmospheric and oceanic optics : Active or adaptive optics # (010.7350) Atmospheric and oceanic optics : Wave-front sensing
Record Number:CaltechAUTHORS:20101206-094102187
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Official Citation:Lianqi Wang, Angel Otarola, and Brent Ellerbroek, "Impact of sodium laser guide star fratricide on multi-conjugate adaptive optics systems," J. Opt. Soc. Am. A 27, A19-A28 (2010)
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:21164
Deposited By: Tony Diaz
Deposited On:08 Dec 2010 17:38
Last Modified:09 Mar 2020 13:19

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