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27 June 2006 A deformable secondary mirror for the VLT
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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.
© (2006) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
R. Arsenault, R. Biasi, D. Gallieni, A. Riccardi, P. Lazzarini, N. Hubin, E. Fedrigo, R. Donaldson, S. Oberti, S. Stroebele, R. Conzelmann, and M. Duchateau "A deformable secondary mirror for the VLT", Proc. SPIE 6272, Advances in Adaptive Optics II, 62720V (27 June 2006);


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