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Proceedings Paper

New challenges for adaptive optics: the OWL 100-m telescope
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Paper Abstract

Adaptive optics will be a key element of future Extremely Large Telescopes (ELTs) which need sharp images both to avoid object confusion and to boost sensitivity to point sources against sky background. A challenging task of correcting turbulence in the visible part of the spectrum is addressed. With an R approximately 10 natural guide star a Strehl ratio (SR) of 0.6 can be achieved at 500 nm, at the cost of an extremely low sky coverage. Thus, use of Multi-Conjugate Adaptive Optics techniques will be essential to widen the field of view (FOV). We summarize our recent theoretical results and show that with 3 deformable mirrors it is realistic to obtain a FOV diameter of 30' - 60' in the visible, or 3' - 6' in the K band. Contrary to the common belief, the layered structure of the turbulence vertical profile is not needed to achieve this limit, neither do we need to know the profile exactly. The wide corrected FOV ensures a reasonably good sky coverage in the near infrared using 4 natural guide stars (60% in the J band at medium Galactic latitudes). Artificial Laser Guide Stars will be needed to correct in the visible, using in addition a faint natural star to measure low-order wavefront aberrations. On ELTs this star can be faint, up to R equals 23, so a good sky coverage can also be obtained. A significant fraction of guide sources at these magnitudes are extragalactic.

Paper Details

Date Published: 7 July 2000
PDF: 8 pages
Proc. SPIE 4007, Adaptive Optical Systems Technology, (7 July 2000); doi: 10.1117/12.390315
Show Author Affiliations
Norbert N. Hubin, European Southern Observatory (Germany)
Miska Le Louarn, European Southern Observatory (Germany)
Marc S. Sarazin, European Southern Observatory (Germany)
Andrei A. Tokovinin, European Southern Observatory (Chile)
Elise Vernet-Viard, European Southern Observatory (Italy)

Published in SPIE Proceedings Vol. 4007:
Adaptive Optical Systems Technology
Peter L. Wizinowich, Editor(s)

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