Laser guide stars using the mesospheric sodium layer at 100 km provide a means of creating a beacon to sense and correct atmospheric turbulence which limits the resolution of large ground based telescopes. Natural guide stars have also been used but their occurence is rare and much of the sky is left unaccessible. Laser guide stars can be positioned to any point in the sky and can track stellar objects thereby allowing almost complete sky coverage even for dim objects. A laser guide star system has been deployed at the Lick Observatory on Mt. Hamilton and a second is under development for the 10 m Keck telescope on Mauna Kea on Hawaii. These laser systems use solid state lasers to pump a liquid dye laser which produces the correct wavelength and near diffraction limited beam. With the advent of fiber optics, the pump and dye master oscillator can be remotely located away from the telescope while the dye amplifiers are mounted directly on the telescope. The Lick system will be shown and results presented. The Keck design will also be shown.
Herbert Friedman received his BS, MS and PhD degrees from the Polytechnic Institute of Brooklyn in Electrophysics. He has worked at Avco Everett Research Lab and LLNL specializing in the areas of high power lasers, broad area electron beams and laser applications such as laser guide stars.
Directions to Lick Observatory: The Observatory is more than 20 miles from downtown San Jose along Mt. Hamilton Road at an elevation of 4200 feet. Take 680 south to Alum Rock Avenue/SR 130. Head east to Mt. Hamilton Road (right turn, continuing on SR 130).The road follows the grade originally laid out over a century ago. It has many sharp curves and is quite narrow in places. There are no services of any kind at Mt. Hamilton or anywhere along the road outside of San Jose. During the winter the road may be closed temporarily due to snowfall.

-----Note added Friday, January 9: The Weather Service predicts no snow on the peak from the current weather system. Lick Observatory states that the road is in good condition. Current road conditions are available at:

Lick Obs