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New methods and technologies that will enable visible wavelength science with laser guidestar AO on the extremely large telescopes

Abstract 116

Submitted by Donald GAVEL


D. Gavel


Lick Observatory, University of California


We discuss new non-traditional methods of wavefront sensing and control that could enable the next generation of wide-field, high sky coverage visible light adaptive optics systems. Imaging and spectroscopy at the diffraction limit becomes increasingly difficult as the science wavelength gets shorter due to the increased accuracy and higher temporal bandwidths needed for the AO correction. Bright guide stars are needed and for any reasonable sky coverage they must be provided by powerful lasers. At the LAO we have been investigating means of using diffractive wavefront sensors to provide the greatest accuracy per guidestar photon. In addition, we are advocating the use of uplink correction, whereby the laser beam is corrected for turbulence on the up-propagation path in order to concentrate the guide star energy into a smaller spot, again, for greater wavefront sensing accuracy per laser photon. In this presentation we give a conceptual framework for visible wavelength AO on ELTs using these and other new approaches currently under investigation, and discuss some of the progress in laboratory and on-sky experiments toward this end.