21 July 2014 A near-infrared tip-tilt sensor for the Keck I laser guide star adaptive optics system
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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.
© (2014) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Peter Wizinowich, Peter Wizinowich, Roger Smith, Roger Smith, Roberto Biasi, Roberto Biasi, Sylvain Cetre, Sylvain Cetre, Richard Dekany, Richard Dekany, Bruno Femenia-Castella, Bruno Femenia-Castella, Jason Fucik, Jason Fucik, David Hale, David Hale, Chris Neyman, Chris Neyman, Dietrich Pescoller, Dietrich Pescoller, Sam Ragland, Sam Ragland, Paul Stomski, Paul Stomski, Mario Andrighettoni, Mario Andrighettoni, Randy Bartos, Randy Bartos, Khanh Bui, Khanh Bui, Andrew Cooper, Andrew Cooper, John Cromer, John Cromer, Marcos van Dam, Marcos van Dam, Michael Hess, Michael Hess, Ean James, Ean James, Jim Lyke, Jim Lyke, Hector Rodriguez, Hector Rodriguez, Thomas Stalcup, 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 (21 July 2014); doi: 10.1117/12.2055279; https://doi.org/10.1117/12.2055279


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