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Proceedings Paper

Improving the alignment of a large telescope structure using thermographic measurements
Author(s): Rogerio Enriquez; David R. Smith
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Paper Abstract

While many telescopes employ some form of thermal monitoring and control to reach their surface accuracy and pointing specifications, such thermal systems are generally not available during field erection of the telescope structure. This presents a problem for large structures, because their size results in structural members with long time constants and substantial total deformations. These characteristics can potentially result in the development of significant thermal gradients across the structure or even across the width of a member. The resulting temperature variations complicate the alignment of critical features, including the main axes. As a result, it would be advantageous to monitor the thermal behavior of a large telescope structure during its construction. In the past, such monitoring was made difficult because of the size of the structure, continuing construction work, or rugged field conditions. However, with the advent of affordable field-ready thermal imaging systems, it is now possible to perform such monitoring. In this paper, we present thermal images of the alidade structure of the Large Millimeter-wave Telescope (LMT/GTM) at its site at 4600m on the top of Volcan Sierra Negra in central Mexico. We present images of typical thermal distributions for different times of day, and compare them with basic analytical models. Finally, we use the thermal imaging results to predict the effects of the temperature distribution on the location of the azimuth bogie connections and the elevation axis.

Paper Details

Date Published: 29 September 2004
PDF: 10 pages
Proc. SPIE 5495, Astronomical Structures and Mechanisms Technology, (29 September 2004); doi: 10.1117/12.552490
Show Author Affiliations
Rogerio Enriquez, Instituto Nacional de Astrofisica, Optica y Electronica (Mexico)
David R. Smith, MERLAB, P.C. (United States)

Published in SPIE Proceedings Vol. 5495:
Astronomical Structures and Mechanisms Technology
Joseph Antebi; Dietrich Lemke, Editor(s)

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