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Distributed Control of Large Deformable Mirrors

MacMartin, Douglas G. and Heimsten, Rikard and Andersen, Torben and Owner-Petersen, Mette (2012) Distributed Control of Large Deformable Mirrors. In: Adaptive Optics Systems III. Proceedings of SPIE. No.8447. Society of Photo-optical Instrumentation Engineers (SPIE) , Bellingham, WA, Art. No. 844710. ISBN 978-0-8194-9148-0.

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While it is attractive to integrate a deformable mirror (DM) for adaptive optics (AO) into the telescope itself rather than using relay optics within an instrument, the resulting large DM can be expensive, particularly for extremely large telescopes. A low-cost approach for building a large DM is to use voice-coil actuators, and rely on feedback from mechanical sensors to improve the dynamic response of the mirror sufficiently so that it can be used in a standard AO control system. The use of inexpensive voice-coil actuators results in many lightly- damped structural resonances within the desired control bandwidth. We present a robust control approach for this problem, and demonstrate performance in a closed-loop AO simulation, incorporating realistic models of low-cost actuators and sensors. The first contribution is to demonstrate that high-bandwidth active damping can be robustly implemented even with non-collocated sensors, by relying on the "acoustic limit" of the structure where the modal bandwidth exceeds the modal spacing. Next we introduce a novel local control approach, which significantly improves the high spatial frequency performance relative to collocated position control, but without the robustness challenges associated with a global control approach. The combination of these "inner" control loops results in DM command response that is demonstrated to be sufficient for integration within an AO system.

Item Type:Book Section
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MacMartin, Douglas G.0000-0003-1987-9417
Additional Information:© 2012 SPIE.
Subject Keywords:Deformable Mirror, Extremely Large Telescopes, Control Systems
Series Name:Proceedings of SPIE
Issue or Number:8447
Record Number:CaltechAUTHORS:20130125-133346621
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Official Citation:Distributed control of large deformable mirrors Douglas G. MacMartin, Rikard Heimsten, Torben Andersen, Mette Owner-Petersen Proc. SPIE 8447, Adaptive Optics Systems III, 844710 (September 13, 2012); doi: 10.1117/12.926940
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36597
Deposited By: Ruth Sustaita
Deposited On:25 Jan 2013 21:53
Last Modified:09 Nov 2021 23:23

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