Adaptive secondary mirror for the 6.5-m conversion of the Multiple Mirror Telescope: first laboratory testing results

Guido Brusa-Zappellini; Armando Riccardi; Valdemaro Biliotti; Ciro Del Vecchio; Piero Salinari; Paolo Stefanini; Paolo Mantegazza; Roberto Biasi; Mario Andrighettoni; Claudio Franchini; Daniele Gallieni

doi:10.1117/12.363599

27 September 1999 Adaptive secondary mirror for the 6.5-m conversion of the Multiple Mirror Telescope: first laboratory testing results

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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Proceedings Volume 3762, Adaptive Optics Systems and Technology; (1999) https://doi.org/10.1117/12.363599
Event: SPIE's International Symposium on Optical Science, Engineering, and Instrumentation, 1999, Denver, CO, United States

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.

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Guido Brusa-Zappellini, Armando Riccardi, Valdemaro Biliotti, Ciro Del Vecchio, Piero Salinari, Paolo Stefanini, Paolo Mantegazza, Roberto Biasi, Mario Andrighettoni, Claudio Franchini, and Daniele Gallieni "Adaptive secondary mirror for the 6.5-m conversion of the Multiple Mirror Telescope: first laboratory testing results", Proc. SPIE 3762, Adaptive Optics Systems and Technology, (27 September 1999); https://doi.org/10.1117/12.363599

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