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Proceedings Paper

Adaptive secondary mirror for the 6.5-m conversion of the Multiple Mirror Telescope: first laboratory testing results
Author(s): Guido Brusa-Zappellini; Armando Riccardi; Valdemaro Biliotti; Ciro Del Vecchio; Piero Salinari; Paolo Stefanini; Paolo Mantegazza; Roberto Biasi; Mario Andrighettoni; Claudio Franchini; Daniele Gallieni
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Paper Abstract

We present the first results of test performed on a reduced size adaptive secondary prototype named P36. The full size unit, named MMT336, is ready to be assembled and it is planned to install it at the 6.5m conversion of the Multiple Mirror Telescope by the end of this year. The design of the final unit consists of: a convex thin deformable mirror whose figure is controlled by 336 electro-magnetic force actuators, a thick reference shell and a third aluminum shell used for actuator support and cooling. The force actuator response function is adjusted using both open and closed loop compensation to obtain an equivalent position actuator thanks to nearly co-located capacitive position sensors. The digital real-time control and the unit monitoring is done using custom-made electronics based on DSPs. The preliminary dynamical test aimed at identifying the P36 mirror response function to obtain a proper dynamics compensation were successful. In fact two main results have been obtained: 1) an accurate identification of the feedforward matrix used to control the mirror 2) settling time of approximately 0.5 ms, well within the specifications. We also complement these lab results with results obtained from simulations of the full size mirror dynamics.

Paper Details

Date Published: 27 September 1999
PDF: 12 pages
Proc. SPIE 3762, Adaptive Optics Systems and Technology, (27 September 1999); doi: 10.1117/12.363599
Show Author Affiliations
Guido Brusa-Zappellini, Osservatorio Astrofisico di Arcetri (United States)
Armando Riccardi, Osservatorio Astrofisico di Arcetri (Italy)
Valdemaro Biliotti, Osservatorio Astrofisico di Arcetri (Italy)
Ciro Del Vecchio, Osservatorio Astrofisico di Arcetri (Italy)
Piero Salinari, Osservatorio Astrofisico di Arcetri (Italy)
Paolo Stefanini, Osservatorio Astrofisico di Arcetri (Italy)
Paolo Mantegazza, Politecnico di Milano (Italy)
Roberto Biasi, Microgate S.r.L. (Italy)
Mario Andrighettoni, Microgate S.r.L. (Italy)
Claudio Franchini, Media Lario S.r.L. (Italy)
Daniele Gallieni, ADS International S.r.L. (Italy)


Published in SPIE Proceedings Vol. 3762:
Adaptive Optics Systems and Technology
Robert K. Tyson; Robert Q. Fugate, Editor(s)

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