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Proceedings Paper

The study on the scheme of dynamic measurement of the main active reflector for FAST
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Paper Abstract

China has embarked on a project to build the world's largest radio telescope, the Five hundred meter Aperture Spherical Telescope (FAST), in a karst depression in southwest Guizhou Province. The telescope is of a modified Arecibo type. We suggest an active main reflector that is spherical in the neutral state but the illuminated aperture of 300m in diameter would be adjusted into a proper paraboloid such that a simple feed could be used at its focus, since the "spherical correction" has be done on the ground. The feed cabin at the focus is supported and driven directly by cables controlled by computer, which avoids a heavy and expensive feed supporting system. Newly developed method and technology for determining the spatial position of 2400 nodes on the main reflector of the FAST are introduced in this paper. Base on the measurements of the position of node under which the down cable are linked, a loop feedback control enables accurately driving the spherical reflector deformed to paraboloid. The key technique of this implementation is the precise measurement of 2400 nodes. In this article, we introduce the scheme of simplified photogrammetry aiming at no lateral shift situation; we analyse the influence of lateral shift; and considering lateral shift, we propose a scheme using rotation platform plus double-eye camera to accomplish the dynamic measurement of the reflector. The result of analysis and testing shows the feasibility and effectivity of the scheme of measurement.

Paper Details

Date Published: 10 July 2008
PDF: 10 pages
Proc. SPIE 7012, Ground-based and Airborne Telescopes II, 70120U (10 July 2008); doi: 10.1117/12.790609
Show Author Affiliations
Lichun Zhu, National Astronomical Observatory (China)
Jinwen Hu, National Astronomical Observatory (China)
Weimin Li, Univ. of Science and Technology of China (China)

Published in SPIE Proceedings Vol. 7012:
Ground-based and Airborne Telescopes II
Larry M. Stepp; Roberto Gilmozzi, Editor(s)

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