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A near-infrared tip-tilt sensor for the Keck I laser guide star adaptive optics system

Wizinowich, Peter and Smith, Roger and Biasi, Roberto and Cetre, Sylvain and Dekany, Richard and Femenia-Castella, Bruno and Fucik, Jason and Hale, David and Neyman, Chris and Pescoller, Dietrich and Ragland, Sam and Stomski, Paul and Andrighettoni, Mario and Bartos, Randy and Bui, Khanh and Cooper, Andrew and Cromer, John and van Dam, Marcos and Hess, Michael and James, Ean and Lyke, Jim and Rodriguez, Hector and Stalcup, Thomas (2014) A near-infrared tip-tilt sensor for the Keck I laser guide star adaptive optics system. In: Adaptive Optics Systems IV. Proceedings of SPIE. No.9148. Society of Photo-Optical Instrumentation Engineers , Bellingham, WA, Art. No. 91482B.

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The sky coverage and performance of laser guide star (LGS) adaptive optics (AO) systems is limited by the natural guide star (NGS) used for low order correction. This limitation can be dramatically reduced by measuring the tip and tilt of the NGS in the near-infrared where the NGS is partially corrected by the LGS AO system and where stars are generally several magnitudes brighter than at visible wavelengths. We present the design of a near-infrared tip-tilt sensor that has recently been integrated with the Keck I telescope’s LGS AO system along with some initial on-sky results. The implementation involved modifications to the AO bench, real-time control system, and higher level controls and operations software that will also be discussed. The tip-tilt sensor is a H2RG-based near-infrared camera with 0.05 arc second pixels. Low noise at high sample rates is achieved by only reading a small region of interest, from 2×2 to 16×16 pixels, centered on an NGS anywhere in the 100 arc second diameter field. The sensor operates at either Ks or H-band using light reflected by a choice of dichroic beamsplitters located in front of the OSIRIS integral field spectrograph.

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Wizinowich, Peter0000-0002-1646-442X
Additional Information:© 2014 SPIE. This material is based in part upon work supported by the National Science Foundation under Grant No. AST-1007058. We would like to acknowledge the technical contributions of Jon Chock, Liz Chock, Shui Kwok, Sudha Laven, Scott Lilley, Jeff Mader, Olivier Martin, Bill Randolph, Kevin Tsubota and Ed Wetherell at WMKO, Ernest Croner at Caltech, and Antonin Bouchez at GMT. We would also like to thank our science team of Tommaso Treu at University of California (UC) Santa Barbara and Mark Morris at UC Los Angeles. The W. M. Keck Observatory is operated as a scientific partnership among the California Institute of Technology, the University of California, and the National Aeronautics and Space Administration. The Observatory was made possible by the generous financial support of the W. M. Keck Foundation. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain.
Funding AgencyGrant Number
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:adaptive optics, laser guide star, tip-tilt sensing, Keck Observatory
Series Name:Proceedings of SPIE
Issue or Number:9148
Record Number:CaltechAUTHORS:20151014-082546213
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Official Citation:Peter Wizinowich ; Roger Smith ; Roberto Biasi ; Sylvain Cetre ; Richard Dekany ; Bruno Femenia-Castella ; Jason Fucik ; David Hale ; Chris Neyman ; Dietrich Pescoller ; Sam Ragland ; Paul Stomski ; Mario Andrighettoni ; Randy Bartos ; Khanh Bui ; Andrew Cooper ; John Cromer ; Marcos van Dam ; Michael Hess ; Ean James ; Jim Lyke ; Hector Rodriguez ; Thomas Stalcup; A near-infrared tip-tilt sensor for the Keck I laser guide star adaptive optics system. Proc. SPIE 9148, Adaptive Optics Systems IV, 91482B (July 21, 2014); doi:10.1117/12.2055279
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:61096
Deposited By: Tony Diaz
Deposited On:14 Oct 2015 19:42
Last Modified:11 Oct 2019 03:56

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