System overview of 30 W and 55 W sodium guide star laser systems

We report on the successful delivery of a 30 W solid-state sodium Guide Star Laser System (GLS) to the W. M. Keck Observatory in 2009, and the demonstration of a 55 W GLS delivered to the Gemini South Observatory in 2010. This paper describes the GLS performance results of both the Keck I and Gemini South GLSs with an emphasis on the system design and delivered performance. The 589 nm output was generated via Sum Frequency Mixing (SFM) of 1064 nm and 1319 nm Nd:YAG lasers in a LBO (Lithium Triborate) nonlinear crystal. The Keck GLS underwent extensive testing and has demonstrated consistent performance with a CW mode-locked output of > 30 W and measured beam quality of M² < 1.2 while locked to the sodium D2a transition. The Keck GLS was installed on the telescope in late 2009 and first light on the sky was achieved in early 2010. Factory testing of the Gemini South GLS shows a CW modelocked output of > 55 W and measured M² ~1.2 while locked to the sodium D2a line center. The Gemini South GLS has produced a maximum power of 76 W at 589 nm with 85 W of 1319 nm and 110 W of 1064 nm as inputs to the SFM, representing a single-pass conversion efficiency of 39%.