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Proceedings Paper

Demonstration of a robust curved carbon fiber reinforced polymer deformable mirror with low surface error
Author(s): Blake Coughenour; S. Mark Ammons; Michael Hart; Robert Romeo; Robert Martin; Matt Rademacher; Hop Bailey
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Paper Abstract

Carbon fiber reinforced polymer (CFRP) composites provide several advantages as a substrate for thin-shell adaptive secondary mirrors, including high stiffness-to-weight ratio and low coefficient of thermal expansion (CTE). We have addressed some of these concerns using a prototype CFRP mirror under actuation. Using 4D and Newton interferometry, we present measurements of surface quality at a range of temperatures. Under actuator relaxation at room temperature, its surface error is low (92 nm RMS) and dominated by edge curvature. This error is reduced further under best actuator correction to 43 nm RMS, placing it into consideration for use in near-IR astronomy. The low surface error internal to the outer ring of actuators - 17 nm RMS at 60°F and 33 nm RMS at 20°F - suggests that larger mirrors will have a similar figure quality under actuator correction on ground-based AO systems. Furthermore, the actuator forces required to correct the figure are small compared to the dynamic range of voice coil actuators (~0.1 N). In addition, surface roughness is characterized to address the effects of high spatial frequency errors.

Paper Details

Date Published: 14 July 2010
PDF: 9 pages
Proc. SPIE 7736, Adaptive Optics Systems II, 77363I (14 July 2010); doi: 10.1117/12.856326
Show Author Affiliations
Blake Coughenour, College of Optical Sciences, The Univ. of Arizona (United States)
S. Mark Ammons, Steward Observatory, The Univ. of Arizona (United States)
Michael Hart, Steward Observatory, The Univ. of Arizona (United States)
Robert Romeo, Composite Mirror Applications, Inc. (United States)
Robert Martin, Composite Mirror Applications, Inc. (United States)
Matt Rademacher, Steward Observatory, The Univ. of Arizona (United States)
Hop Bailey, Steward Observatory, The Univ. of Arizona (United States)

Published in SPIE Proceedings Vol. 7736:
Adaptive Optics Systems II
Brent L. Ellerbroek; Michael Hart; Norbert Hubin; Peter L. Wizinowich, Editor(s)

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