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Proceedings Paper

A deformable secondary mirror for the VLT
Author(s): R. Arsenault; R. Biasi; D. Gallieni; A. Riccardi; P. Lazzarini; N. Hubin; E. Fedrigo; R. Donaldson; S. Oberti; S. Stroebele; R. Conzelmann; M. Duchateau
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Paper Abstract

ESO has initiated in June 2004 a feasibility study to investigate the possibility to retro-fit one of the VLT 8 m telescope with a deformable secondary mirror (DSM). The scope of this effort has been broadened to a concept of Adaptive Optics Facility (adaptive telescope with adapted instrument park). The feasibility study, conducted by MicroGate, ADS Intl and the INAF-Osservatorio Astrofisico di Arcetri, has been successful (no show stopper identified) and has provided an elegant design of an alternate M2-Unit for the VLT. It features a 1170 actuators DSM based on the voice coil force actuators coupled with capacitive sensors. An 80 kHz internal control loop allows implementing of electronic damping. The simulations performed have shown a fitting error of 62.5 nm rms (ro = 12.1 cm @ 30 deg. zenith) with a 2mm thin shell and 1.5 kW of heat dissipation. The design shall provide a full stroke of ~50 μm and a rise time of < 1 msec. The DSM will be focused and "centered" by a Hexapod and a bi-positions electro-mechanism will allow switching from Nasmyth to Cassegrain focus configuration. Several features are planned to ease maintenance and diagnostic.

Paper Details

Date Published: 27 June 2006
PDF: 12 pages
Proc. SPIE 6272, Advances in Adaptive Optics II, 62720V (27 June 2006); doi: 10.1117/12.672879
Show Author Affiliations
R. Arsenault, European Southern Observatory (Germany)
R. Biasi, MicroGate S.r.l. (Italy)
D. Gallieni, ADS International Srl (Italy)
A. Riccardi, INAF-Osservatorio Astrofisico de Arcetri (Italy)
P. Lazzarini, ADS International Srl (Italy)
N. Hubin, European Southern Observatory (Germany)
E. Fedrigo, European Southern Observatory (Germany)
R. Donaldson, European Southern Observatory (Germany)
S. Oberti, European Southern Observatory (Germany)
S. Stroebele, European Southern Observatory (Germany)
R. Conzelmann, European Southern Observatory (Germany)
M. Duchateau, European Southern Observatory (Germany)

Published in SPIE Proceedings Vol. 6272:
Advances in Adaptive Optics II
Brent L. Ellerbroek; Domenico Bonaccini Calia, Editor(s)

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