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Proceedings Paper

Design and development of a 329-segment tip-tilt piston mirror array for space-based adaptive optics
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Paper Abstract

We report on the development of a new MEMS deformable mirror (DM) system for the hyper-contrast visible nulling coronagraph architecture designed by the Jet Propulsion Laboratory for NASA's Terrestrial Planet Finding (TPF) mission. The new DM is based largely upon existing lightweight, low power MEMS DM technology at Boston University (BU), tailored to the rigorous optical and mechanical requirements of the nulling coronagraph. It consists of 329-hexagonal segments on a 600μm pitch, each with tip/tilt and piston degrees of freedom. The mirror segments have 1μm of stroke, a tip/tilt range of 600 arc-seconds, and maintain their figure to within 2nm RMS under actuation. The polished polycrystalline silicon mirror segments have a surface roughness of 5nm RMS and an average curvature of 270mm. Designing a mirror segment that maintains its figure during actuation was a very significant challenge faced during DM development. Two design concepts were pursued in parallel to address this challenge. The first design uses a thick, epitaxial grown polysilicon mirror layer to add rigidity to the mirror segment. The second design reduces mirror surface bending by decoupling actuator diaphragm motion from the mirror surface motion. This is done using flexure cuts around the mirror post in the actuator diaphragm. Both DM architectures and their polysilicon microfabrication process are presented. Recent optical and electromechanical characterization results will also be discussed, in addition to plans for further improvement of DM figure to satisfy nulling coronagraph optical requirements.

Paper Details

Date Published: 23 January 2006
PDF: 9 pages
Proc. SPIE 6113, MEMS/MOEMS Components and Their Applications III, 61130O (23 January 2006); doi: 10.1117/12.651373
Show Author Affiliations
Jason B. Stewart, Boston Univ. (United States)
Thomas G. Bifano, Boston Univ. (United States)
Boston Micromachines Corp. (United States)
Paul Bierden, Boston Micromachines Corp. (United States)
Steven Cornelissen, Boston Micromachines Corp. (United States)
Timothy Cook, Boston Univ. (United States)
B. Martin Levine, Jet Propulsion Lab. (United States)


Published in SPIE Proceedings Vol. 6113:
MEMS/MOEMS Components and Their Applications III
Scot S. Olivier; Srinivas A. Tadigadapa; Albert K. Henning, Editor(s)

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