Share Email Print

Proceedings Paper

Sodium beacon wavefront sensing for the Euro50 telescope in the presence of perspective elongation
Format Member Price Non-Member Price
PDF $14.40 $18.00

Paper Abstract

To obtain full sky coverage, astronomical adaptive optics systems require Na Sodium Beacons (SBs) (also referred to as Laser Guide Stars or LGSs) located at heights extending from 85 to 100 km. When viewed at the edge of large telescopes these SBs appear elongated. For the Euro50 50 meter aperture telecopes this elongation amounts to 6 to 9 arcseconds when the laser is launched from a point on the telescope axis. This is substantially larger than the -0.6 arcsec FWHM SB when viewed near the telescope center. This so-called "perspective elongation" substantially decreases the sensitivity of SB aided adaptive optics. We describe a way of removing this elongation when using pulsed lasers. It uses rapid (microsecond) refocusing of the telescope with the aid of birefringent lenses and polarization modulators. We present an outline of the SB wavefront sensor for the Euro50.

Paper Details

Date Published: 7 July 2004
PDF: 10 pages
Proc. SPIE 5382, Second Backaskog Workshop on Extremely Large Telescopes, (7 July 2004); doi: 10.1117/12.566229
Show Author Affiliations
Jacques Maurice Beckers, Univ. of Chicago (United States)
Lund Observatory (Sweden)
Mette Owner-Petersen, Lund Observatory (Sweden)
Torben E. Andersen, Lund Observatory (Sweden)

Published in SPIE Proceedings Vol. 5382:
Second Backaskog Workshop on Extremely Large Telescopes
Arne L. Ardeberg; Torben Andersen, Editor(s)

© SPIE. Terms of Use
Back to Top