Athermal design of the optical tube assemblies for the ESO VLT four laser guidestar facility
conference paper
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.
Topics
TNO Identifier
442998
ISSN
0277786X
ISBN
9780819487599
Article nr.
814905
Source title
Astronomical Adaptive Optics Systems and Applications IV, 21-24 August 2011, San Diego, CA, USA
Collation
7 p.
Pages
814905-1 - 814905-7
Files
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