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Proceedings Paper

Athermal design of the optical tube assemblies for the ESO VLT Four Laser Guidestar Facility
Author(s): R. Henselmans; D. Nijkerk; M. Lemmen; N. Rijnveld; F. Kamphues
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Paper Abstract

TNO is developing the Optical Tube Asssemblies (OTAs) for the ESO VLT Four Laser Guide Star Facility. The OTAs are Galilean 20x beam expanders, expanding a Ø15 mm input beam to a steerable Ø300 mm output beam with a wavefront quality requirement of 50 nm rms. The allowed defocus under the influence of the changing environmental air temperature (0-15°C, -0.7°C/hr gradient) is only 0.2 waves. The thermal behaviour of the system has been analyzed by combining optical, lumped mass and FE analyses. A design that is passively athermalized over a large temperature range as well as under the influence of thermal gradients has been developed. Extensive thermal testing has shown the system performs as required. This paper describes the design and test results.

Paper Details

Date Published: 12 September 2011
PDF: 7 pages
Proc. SPIE 8149, Astronomical Adaptive Optics Systems and Applications IV, 814905 (12 September 2011); doi: 10.1117/12.893845
Show Author Affiliations
R. Henselmans, TNO (Netherlands)
D. Nijkerk, TNO (Netherlands)
M. Lemmen, TNO (Netherlands)
N. Rijnveld, TNO (Netherlands)
F. Kamphues, TNO (Netherlands)

Published in SPIE Proceedings Vol. 8149:
Astronomical Adaptive Optics Systems and Applications IV
Robert K. Tyson; Michael Hart, Editor(s)

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