Laser beacon system for the UnISIS adaptive optics system at the Mount Wilson 2.5-m telescope

摘要

A 50 watt excimer laser (lambda equals 351 nm) has been installed at the Mt. Wilson 2.5- meter telescope in California as part of the UnISIS adaptive optics system. This laser is used to produce Rayleigh guide stars 18 km above Mt. Wilson. In its initial configuration the projection optics are used to create a single laser guide star. The optical system is designed to allow an easy switch to accommodate three laser guide stars if (1) the laser return signal is sufficiently bright and (2) the laser guide star wavefront sensor has a read noise low enough to detect the split signal. The three guide stars are projected simultaneously in a triangular configuration above the telescope pupil. This three laser guide star system design is the first to confront directly the problem of focal anisoplanatism with an array of laser guide stars. The three guide star array provides a test for theoretical analyses of arrays of laser guide stars which will be an inevitable part of the adaptive optics systems of 8-meter and 10-meter class telescopes.