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Proceedings Paper

Laser guide stars and models of atmospheric turbulence
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Paper Abstract

We propose a modified approach to form a laser guide star (LGS) with a wide, collimated laser beam launched through the full aperture of a telescope. Using a special form of field stop (diaphragm) uniquely positioned for each subapertures, the wavefront sensor "sees" only a small part of the source corresponding to the area on the sky, which is cut out by the field stop. Each of these spherical waves subtends the area of a separate subaperture at the telescope pupil. Thus, the LGS is formed of a set of spherical waves. Since the linear size of the subaperture is approximately equal to the coherence radius, the measured wavefront can be restored as a smooth phase function. In the paper use of this scheme is investigated. It is well know that adaptive optical system (AOS) operating on astronomical telescopes with a LGS has limitations due to the effect of the focal anisoplanatism, since the spherical wavefront that comes from the LGS does not pass trough the same portion of turbulence atmosphere as plane wavefront of natural guide stars (NGS) located at an infinite distance from ground. There have been proposed several different approaches to overcome the focal anisoplanatism. In the method proposed by Buscher et al, sensing of the turbulence-induced wavefront distortions is performed on the outgoing path of a collimated laser beam by forming an extended intensity pattern in the atmosphere and analyzing its distortion from the ground. In a recent work, the prospect of using a collimated laser beam launched through the main telescope has been revisited and a special wavefront sensing scheme has been proposed. In the present paper we show possible implementation for this scheme and give analytical analysis of AOS performance.

Paper Details

Date Published: 14 February 2008
PDF: 7 pages
Proc. SPIE 6936, Fourteenth International Symposium on Atmospheric and Ocean Optics/Atmospheric Physics, 69360I (14 February 2008); doi: 10.1117/12.783065
Show Author Affiliations
L. A. Bol'basova, Institute of Atmospheric Optics (Russia)
Tomsk State Univ. (Russia)
V. P. Lukin, Institute of Atmospheric Optics (Russia)
Tomsk State Univ. (Russia)


Published in SPIE Proceedings Vol. 6936:
Fourteenth International Symposium on Atmospheric and Ocean Optics/Atmospheric Physics

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