Rayleigh Laser Guide Star Systems: Application to UnISIS

Laser guide stars created by Rayleigh scattering provide a reasonable means to monitor atmospheric wavefront distortions for real-time correction by adaptive optics systems. Because of the $\lambda^{-4}$ wavelength dependence of Rayleigh scattering, short wavelength lasers are a logical first choice for astronomical laser guide star systems, and in this paper we describe the results from a sustained experimental effort to integrated into an adaptive optics system a 351 nm Rayleigh laser guide star created at an altitude of 20 km (above MSL) at the Mt. Wilson 2.5-m telescope. In addition to providing obvious scientific benefits, the 351 nm laser guide star projected by UnISIS is "Stealth qualified: in terms of the FAA and airplane avoidance. Due to the excellent return signal at the wavefront sensor, there is no doubt that future applications will be found for short-wavelength Rayleigh scattered laser guide stars.