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Proceedings Paper

The actuator design and the experimental tests of a new technology large deformable mirror for visible wavelengths adaptive optics
Author(s): Ciro Del Vecchio; Guido Agapito; Carmelo Arcidiacono; Luca Carbonaro; Fabrizio Marignetti; Enzo De Santis; Valdemaro Biliotti; Armando Riccardi
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Paper Abstract

Recently, Adaptive Secondary Mirrors showed excellent on-sky results in the Near Infrared wavelengths. They currently provide 30mm inter-actuator spacing and about 1 kHz bandwidth. Pushing these devices to be operated at visible wavelengths is a challenging task. Compared to the current systems, working in the infrared, the more demanding requirements are the higher spatial resolution and the greater correction bandwidth. In fact, the turbulence scale is shorter and the parameter variation is faster. Typically, the former is not larger than 25 mm (projected on the secondary mirror) and the latter is 2 kHz, therefore the actuator has to be more slender and faster than the current ones. With a soft magnetic composite core, a dual-stator and a single-mover, VRALA, the actuator discussed in this paper, attains unprecedented performances with a negligible thermal impact. Pre-shaping the current required to deliver a given stroke greatly simplifies the control system, whose output supplies the current generator. As the inductance depends on the mover position, the electronics of this generator, provided with an inductance measure circuit, works also as a displacement sensor, supplying the control system with an accurate feed-back signal. A preliminary prototype, built according to the several FEA thermo-magnetic analyses, has undergone some preliminary laboratory tests. The results of these checks, matching the design results in terms of power and force, show that the the magnetic design addresses the severe specifications.

Paper Details

Date Published: 13 September 2012
PDF: 10 pages
Proc. SPIE 8447, Adaptive Optics Systems III, 844708 (13 September 2012); doi: 10.1117/12.926184
Show Author Affiliations
Ciro Del Vecchio, INAF - Osservatorio Astrofisico di Arcetri (Italy)
Guido Agapito, INAF - Osservatorio Astrofisico di Arcetri (Italy)
Carmelo Arcidiacono, INAF - Osservatorio Astrofisico di Arcetri (Italy)
Luca Carbonaro, INAF - Osservatorio Astrofisico di Arcetri (Italy)
Fabrizio Marignetti, Univ. degli Studi di Cassino (Italy)
Enzo De Santis, Univ. degli Studi di Cassino (Italy)
Valdemaro Biliotti, INAF - Osservatorio Astrofisico di Arcetri (Italy)
Armando Riccardi, INAF - Osservatorio Astrofisico di Arcetri (Italy)

Published in SPIE Proceedings Vol. 8447:
Adaptive Optics Systems III
Brent L. Ellerbroek; Enrico Marchetti; Jean-Pierre Véran, Editor(s)

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