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Proceedings Paper

Dynamic Optical Deformations Of A Chopping Secondary Mirror
Author(s): Daniel Vukobratovich; Robert DiTolla; Ralph M. Richard
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Paper Abstract

The finite element method was used to analyze the optical performance of the Space Infrared Telescope Facility (SIRTF) fused-silica secondary mirror as it is subjected to a dynamic chopping motion. The chopping motion was assumed to be of quasi-square wave form with the mirror stationary during a dwell period following the actual chop rotation. The primary optical deformation was "ringing" during the dwell period; damping during the dwell time (20 ms) was not effective. For a given chopping motion, the magnitude of the optical deflections could be reduced by proper choice of the support points, by increasing the stiffness of the mirror, reducing the magnitude of the chop angle, and/or increasing the chop period. Prescribed acceleration versus time during the chop motion affects the optical deformations as well. There are optimum support-point locations for each type of motion. Tapering the back of the secondary mirror does not significantly affect optical deformation provided that supports are located at the optimum points. For the best trade of mass moment of inertia against deformation, lightweight mirror geometries should be used.

Paper Details

Date Published: 23 February 1985
PDF: 6 pages
Proc. SPIE 0572, Infrared Technology XI, (23 February 1985); doi: 10.1117/12.950688
Show Author Affiliations
Daniel Vukobratovich, University of Arizona (United States)
Robert DiTolla, University of Arizona (United States)
Ralph M. Richard, University of Arizona (United States)

Published in SPIE Proceedings Vol. 0572:
Infrared Technology XI
Richard A. Mollicone; Irving J. Spiro, Editor(s)

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