Rapid refocusing system for the Euro50 telescope aimed at removing the perspective elongation of laser beacons

Jacques M. Beckers; Mette Owner-Petersen; Torben Andersen

doi:10.1117/12.504238

24 December 2003 Rapid refocusing system for the Euro50 telescope aimed at removing the perspective elongation of laser beacons

Jacques M. Beckers, Mette Owner-Petersen, Torben Andersen

Author Affiliations +

Proceedings Volume 5169, Astronomical Adaptive Optics Systems and Applications; (2003) https://doi.org/10.1117/12.504238
Event: Optical Science and Technology, SPIE's 48th Annual Meeting, 2003, San Diego, California, United States

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 telescopes 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.

Citation Download Citation

Jacques M. Beckers, Mette Owner-Petersen, and Torben Andersen "Rapid refocusing system for the Euro50 telescope aimed at removing the perspective elongation of laser beacons", Proc. SPIE 5169, Astronomical Adaptive Optics Systems and Applications, (24 December 2003); https://doi.org/10.1117/12.504238

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