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Proceedings Paper

Keck II laser guide star AO system and performance with the TOPTICA/MPBC laser
Author(s): Jason C. Y. Chin; Peter Wizinowich; Ed Wetherell; Scott Lilley; Sylvain Cetre; Sam Ragland; Drew Medeiros; Kevin Tsubota; Greg Doppmann; Angel Otarola; Kai Wei
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Paper Abstract

The Keck II Laser Guide Star (LGS) Adaptive Optics (AO) System was upgraded from a dye laser to a TOPTICA/MPBC Raman-Fibre Amplification (RFA) laser in December 2015. The W. M. Keck Observatory (WMKO) has been operating its AO system with a LGS for science since 2004 using a first generation 15 W dye laser. Using the latest diode pump laser technology, Raman amplification, and a well-tuned second harmonic generator (SHG), this Next Generation Laser (NGL) is able to produce a highly stable 589 nm laser beam with the required power, wavelength and mode quality. The beam’s linear polarization and continuous wave format along with optical back pumping are designed to improve the sodium atom coupling efficiency over previously operated sodium-wavelength lasers. The efficiency and operability of the new laser has also been improved by reducing its required input power and cooling, size, and the manpower to operate and maintain it.

The new laser has been implemented on the telescope’s elevation ring with its electronics installed on a new Nasmyth sub-platform, with the capacity to support up to three laser systems for future upgrades. The laser is projected from behind the telescope’s secondary mirror using the recently implemented center launch system (CLS) to reduce LGS spot size. We will present the new laser system and its performance with respect to power, stability, wavelength, spot size, optical repumping, polarization, efficiency, and its return with respect to pointing alignment to the magnetic field. Preliminary LGSAO performance is presented with the system returning to science operations. We will also provide an update on current and future upgrades at the WMKO.

Paper Details

Date Published: 26 July 2016
PDF: 19 pages
Proc. SPIE 9909, Adaptive Optics Systems V, 99090S (26 July 2016); doi: 10.1117/12.2233138
Show Author Affiliations
Jason C. Y. Chin, W. M. Keck Observatory (United States)
Peter Wizinowich, W. M. Keck Observatory (United States)
Ed Wetherell, W. M. Keck Observatory (United States)
Scott Lilley, W. M. Keck Observatory (United States)
Sylvain Cetre, W. M. Keck Observatory (United States)
Sam Ragland, W. M. Keck Observatory (United States)
Drew Medeiros, W. M. Keck Observatory (United States)
Kevin Tsubota, W. M. Keck Observatory (United States)
Greg Doppmann, W. M. Keck Observatory (United States)
Angel Otarola, Thirty Meter Telescope (United States)
Kai Wei, Thirty Meter Telescope (United States)


Published in SPIE Proceedings Vol. 9909:
Adaptive Optics Systems V
Enrico Marchetti; Laird M. Close; Jean-Pierre Véran, Editor(s)

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