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We present the requirements, design, and resulting new layout for the laser guide star/natural guide star (LGUNGS) adaptive optics (AO) system on the 3-meter Shane telescope at Lick Observatory. This layout transforms our engineering prototype into a stable, reliable, maintainable end-user-oriented system, suitable for use as a facility instrument. Important new features include convenient calibration using proven phase-shifting diffraction interferometer or phase-diversity techniques'; a new wavefront sensor design that uses the science path's f/28.5 parabola; improved field stop mechanics for better Rayleigh- scatter rejection in LGS mode and better guide-star selection NGS mode; high-sensitivity, wide-field acquisition camera; and significant improvements in adjustment motorization and optomechanical stability. Keywords: Adaptive optics, Lick Observatory, laser guide-star, natural guide-star, phase-shifting diffraction interferometer, phase-diversity, optical design, Bravais lens

Results of experiments with the laser guide star adaptive optics system on the 3-meter Shane telescope at Lick Observatory have demonstrated a factor of 4 performance improvement over previous results. Stellar images recorded at a wavelength of 2 micrometers were corrected to over 40 percent of the theoretical diffraction-limited peak intensity. For the previous two years, this sodium-layer laser guide star system has corrected stellar images at this wavelength to approximately 10 percent of the theoretical peak intensity limit. After a campaign to improve the beam quality of the laser system, and to improve calibration accuracy and stability of the adaptive optics system using new techniques for phase retrieval and phase-shifting diffraction interferometry, the system performance has been substantially increased. The next step will be to use the Lick system for astronomical science observations, and to demonstrate this level of performance with the new system being installed on the 10-meter Keck II telescope.

A laser system to generate sodium-layer guide stars has been designed, built and delivered to the Keck Observatory in Hawaii. The system uses frequency doubled YAG lasers to pump liquid dye lasers and produces 20 W of average power. The design and performance results of this laser system are presented.

A tip-tilt control system has been built as part of the adaptive optics system for the Keck II telescope on Mauna Kea in Hawaii. This system is used to correct for wavefront tip-tilt when the adaptive optics system is in the laser guide star mode, and it uses a natural star as the reference. The system consists of a tip-tilt sensor, fast steering mirror, and digital controller. The tip-tilt sensor is based on a quadrant lens assembly with fiber-optics coupling to four photon counting silicon avalanche photodiodes. The fast steering mirror mount has three PZT actuators with position sensor, and an 8 inch Silicon Carbide lightweight mirror. The controller accommodates a range of integration times, and includes automatic light level control, and an adaptive control algorithm which optimizes control performance with changing tilt star image sizes. The design and performance characteristics of a tip- tilt control system for the Keck II telescope are presented.

The laser guide star adaptive optics system currently being developed for the Keck 2 telescope consists of several major subsystems: the optical bench, wavefront control, user interface and supervisory control, and the laser system. The paper describes the design and implementation of the wavefront control subsystem that controls a 349 actuator deformable mirror for high order correction and tip-tilt mirrors for stabilizing the image and laser positions.

The installation and performance characteristics of a 20 W sodium beacon laser system for the 3 m Shane telescope at the Lick Observatory are presented.

The use of sodium-layer laser guide stars for adaptive optics systems greatly enhances the sky coverage as compared to systems using natural guide stars. In order to demonstrate the feasibility of a sodium-layer guide star, a 20 W pulsed dye laser system has been designed and installed on the 3 meter Shane telescope at the Lick Observatory, Mt. Hamilton, California. The adaptive optics system used in conjunction with the laser guide star system has been described elsewhere1 and has already demonstrated diffraction limited images at the 2.2 micron wavelength using natural guide stars. The integration of the sodium laser guide star and the adaptive optics systems represents the first such installation on an astronomical telescope.

The design and background data for a sodium layer laser guide star system to be installed on the 3 meter telescope at Lick Observatory is presented. A 30 W dye laser at 589 nm and 10 kHz will be mounted on the telescope and will be pumped by fiber coupled, frequency doubled YAG laser located in a separate room.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.