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Proceedings Paper

Design Of The Apache Point Observatory 3.5m Telescope II. Deformation Analysis Of The Primary Mirror
Author(s): Walter A. Siegmund; Edward J. Mannery; James Radochia; Paul E. Gillett
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Paper Abstract

We have calculated the deflection of the surface of a 3.5 meter diameter borosilicate mirror using the finite element method. The mirror is a 0.46 m thick honeycomb structure with 25 mm thick face plates and 13 mm ribs. The cell spacing is 0.192 m and is regular except near the inner and outer perimeters. Axial support for the mirror will be provided by 48 air pistons. The air pressure in the pistons will be regulated to balance the axial component of the mirror weight. The axial air pistons are located near nodes in the rib pattern of the honeycomb thereby facilitating access to the interior of the mirror for ventilation and transverse support. A simple wind loading case was examined and the resulting deflections are shown to be small. The effects of thickness variations in fabrication of the mirror are presented and are small for the magnitudes of the variations expected. Several thermal load cases are described.

Paper Details

Date Published: 20 August 1986
PDF: 13 pages
Proc. SPIE 0628, Advanced Technology Optical Telescopes III, (20 August 1986); doi: 10.1117/12.963554
Show Author Affiliations
Walter A. Siegmund, University of Washington (United States)
Edward J. Mannery, University of Washington (United States)
James Radochia, JLR Computer Analysis (United States)
Paul E. Gillett, RGA Consulting Engineers (United States)

Published in SPIE Proceedings Vol. 0628:
Advanced Technology Optical Telescopes III
Lawrence D. Barr, Editor(s)

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