Edward Kibblewhite, University of Chicago
Keywords: Adaptive Optics
Abstract:
We report closed-loop results obtained from an adaptive optics system with multiple laser guide beacons. The system is mounted on the 6.5 m MMT telescope in Arizona, and is designed to explore advanced altitude-conjugated techniques for wide-field image compensation. Five beacons are made by Rayleigh scattering of laser beams at 532 nm integrated over a range from 20 to 29 km by dynamic refocus of the telescope optics. The return light is analyzed by a unique Shack-Hartmann sensor that places all five beacons on a single detector, with electronic shuttering to implement the beacon range gate. The wavefront sensor divides the 6.5 m telescope pupil into 60 subapertures, and wavefront correction is applied with the telescope’s unique deformable secondary mirror. The system has now begun operations as a tool for astronomical science, in a mode in which the boundary-layer turbulence, close to the telescope, is compensated. Image quality of 0.2-0.3 arcsec is routinely delivered in the near infrared bands from 1.2 to 2.5 microns over a field of view of 2 arcmin. Although it does not reach the diffraction limit, this represents a 3 to 4-fold improvement in resolution over the natural seeing, and a field of view an order of magnitude larger than conventional adaptive optics systems deliver. In this paper we present performance metrics including images of the core of a globular cluster where correction is almost uniform across the full field, and preliminary results from the first scientific program to take advantage of the system.
Date of Conference: September 1-4. 2009
Track: Adaptive Optics