2 GENERATIONS OF LASER-GUIDE-STAR ADAPTIVE-OPTICS EXPERIMENTS AT THE STARFIRE OPTICAL-RANGE

We report results that were obtained with two generations (Generation I and Generation II) of a laser-guide-star adaptive-optics system that is capable of continuous compensation at 65-Hz (Generation I) and 130 -Hz (Generation II) closed-loop bandwidths on a 1.5-m telescope. We us ed a copper-vapor laser that was focused at a 10-km range as the laser guide star and a range-gated Shack-Hartmann sensor to operate a conti nuous-facesheet deformable mirror that controlled either 149 or 241 ac tuators. We used a separate full-aperture sensor and a steering mirror to remove overall tilt. System performance was measured by imaging st ars with a high-resolution CCD camera in a narrow spectral band that w as centered at 0.88 mu m, from which we computed point-spread function s, optical transfer functions, and Strehl ratios. Using the laser guid e star, we achieved a FWHM image resolution of 0.13 arcsec and a Streh l ratio of 0.48. Using a natural guide star, we achieved a Strehl rati o of 0.64 at 0.13 arcsec FWHM resolution. We also obtained compensated images of the Trapezium region in Orion in H-alpha light, using only the laser guide star.