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Proceedings Paper

A laser tomography test bed for extremely large telescopes
Author(s): R. Conan; P. Piatrou; F. Rigaut; K. Uhlendorf
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Paper Abstract

The Advanced Instrumentation and Technology Center at the Australian National University is building a Laser Tomography Adaptive Optics Test Bed for Extremely Large Telescopes. The optical test bench is using three Laser Guide Stars (LGS) propagating through three phase screens. The LGS wavefronts are sampled with a 16 × 16 Shack-Hartmann wavefront sensor (SH-WFS). Cone effect, spot elongation and Sodium layer density fluctuations are reproduced on the bench. Two Natural Guide Stars (NGS), on-axis and off-axis, are also added to the bench. The wavefront of the on-axis NGS is corrected with a DM located in the optical path of both the LGSs and the on-axis NGS. The DM commands are derived from the tomographic estimate of the on-axis NGS wavefront using the measurements of the 3 LGS WFSs. The off-axis NGS wavefront is sampled with a 6 × 6 SH-WFS and is emulating tip-tilt, focus and truth sensing. A DM located in front of the off-axis NGS WFS is correcting the off-axis NGS wavefront. The commands of this DM are also derived from the tomographic reconstructor. In the paper, the design of the LTAO test bed is presented.

Paper Details

Date Published: 4 August 2014
PDF: 17 pages
Proc. SPIE 9148, Adaptive Optics Systems IV, 91485T (4 August 2014); doi: 10.1117/12.2054471
Show Author Affiliations
R. Conan, The Australian National Univ. (Australia)
P. Piatrou, The Australian National Univ. (Australia)
F. Rigaut, The Australian National Univ. (Australia)
K. Uhlendorf, The Australian National Univ. (Germany)


Published in SPIE Proceedings Vol. 9148:
Adaptive Optics Systems IV
Enrico Marchetti; Laird M. Close; Jean-Pierre Véran, Editor(s)

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