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

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

doi:10.1117/12.2055279

21 July 2014 A near-infrared tip-tilt sensor for the Keck I laser guide star adaptive optics system

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

Author Affiliations +

Proceedings Volume 9148, Adaptive Optics Systems IV; 91482B (2014) https://doi.org/10.1117/12.2055279
Event: SPIE Astronomical Telescopes + Instrumentation, 2014, Montréal, Quebec, Canada

Abstract

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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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, and 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); https://doi.org/10.1117/12.2055279

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