Lockheed Martin Coherent Technologies (LMCT) reports on the development of a compact, scalable versatile optical waveform sodium guidestar laser system (GLS) suitable for Adaptive Optics (AO) systems on Extremely Large Telescopes (ELT's) and smaller telescopes. We have successfully completed phase 1 of the three-phase, 4½ year, NSF funded, National Optical Astronomy Observatory (NOAO) sponsored program. The GLS can be optimized for efficient sodium layer interaction for each telescope / AO system with mitigation of parasitic effects such as Rayleigh or cirrus cloud scatter of adjacent beacon light in multi-conjugate adaptive optics (MCAO) and spot elongation in the sodium layer from off-axis light launch in an ELT. The proposed solid-state laser architecture incorporates patent-pending self-imaging waveguide technology and is based on a set of requirements that was determined after extensive discussions with the astronomy adaptive optics community. This paper presents data on single beacon, Rayleigh compensating, and elongation compensating waveforms that were demonstrated through all stages of the architecture, as well as demonstrated and anticipated 589 nm power levels for each waveform. The design of the master oscillator power amplifier (MOPA) architecture, modulation methodology, power amplification, and sum-frequency generation stages is also described. System attributes, including size, weight, and power will also be discussed.
We report on the first successful installation of a commercial solid-state sodium guidestar laser system (GLS). The GLS developed at LMCT was delivered to Gemini North Observatory in February of 2005. The laser is a single beacon system that implements a novel laser architecture and represents a critical step towards addressing the need of the astronomy and military adaptive optics (AO) communities for a robust turn-key commercial GLS. The laser was installed on the center section of the 8 m Gemini North telescope, with the output beam relayed to a laser launch telescope located behind the 1 m diameter secondary mirror. The laser went through a three week performance evaluation between November and December 2005 wherein it consistently generated 12 W average power with measured M<sup>2</sup> < 1.1 while locked to the D2 line at +/- 100 MHz. The system was required to perform during a 12-hour test period during three runs of 4-6 consecutive nights each. The laser architecture is based on continuous wave (CW) mode-locked solid-state lasers. The mode-locked format enables more efficient SFG conversion, and dispenses with complex resonant intensity enhancement systems and injection-locking electronics. The linearly-polarized, near-diffraction-limited, modelocked 1319 nm and 1064 nm pulses are generated in separate dual-head diode-pumped resonators. The two IR pulses are input into a single-stage, 30 mm PPSLT sum-frequency generation (SFG) crystal provided by Physical Science, Inc. Visible (589 nm) power of >16 W have been generated, representing a conversion efficiency of 40%.
Coherent Technologies, Inc. (CTI) is developing the first commercial solid-state sodium beacon laser guidestar (LGS): a critical step towards addressing the need of the astronomy adaptive optics (AO) community for a robust turn-key commercial LGS that can be upgraded for different observatory facilities and for different AO formats - including multi-conjugate AO (MCAO) and future extra-large telescopes. The LGS that is currently being developed will be a 14 W single beacon system to be installed on the center section of the Gemini North telescope in Fall 2004. This paper describes the Gemini North LGS requirements, the design of the laser with design trades against other LGS architectures; the functionality of the automated remote laser control system; latest size, weight, power, and performance data; and the current status of the program.