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Proceedings Paper

High performance holography mapping with the LMT
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Paper Abstract

When making holography measurements on a large telescope, there are many factors that make it difficult to obtain a consistent map. Two of these factors are variations of the satellite and temperature-induced deformations of the reflecting surface. The former requires frequent returns to the center of the map to check the satellite and the latter requires that the map be completed rapidly and at night. While holography mapping has traditionally been performed using point-by-point or raster scanning, these methods involve substantial overhead in the frequent movements back to the center of the map. In performing holography maps of the Large Millimeter Telescope (LMT) for the first light campaign, the observing team proposed a radial scanning approach. This strategy has the advantage that every scan passes through the center of the map. However, such a scan results in a disproportionate amount of telescope time near the center region. To achieve more uniform coverage, the team proposed a velocity profile that is inversely proportional to the distance from the center of the map. Because the velocity profile is defined with respect to position rather than time, this new approach required an extension of the existing parametric scanning capabilities at the LMT. The high axis rates resulting from this velocity profile present additional challenges. This paper describes the implementation and performance results for holography maps that use a radial scan pattern with a position-dependent velocity profile at the LMT. Both theoretical and experimental results are presented.

Paper Details

Date Published: 17 September 2012
PDF: 10 pages
Proc. SPIE 8444, Ground-based and Airborne Telescopes IV, 84442N (17 September 2012); doi: 10.1117/12.926252
Show Author Affiliations
David R. Smith, MERLAB, P.C. (United States)
Kamal Souccar, Large Millimeter Telescope, Univ. of Massachusetts Amherst (United States)


Published in SPIE Proceedings Vol. 8444:
Ground-based and Airborne Telescopes IV
Larry M. Stepp; Roberto Gilmozzi; Helen J. Hall, Editor(s)

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