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

Lichun Zhu; Jinwen Hu; Weimin Li

doi:10.1117/12.790609

10 July 2008 The study on the scheme of dynamic measurement of the main active reflector for FAST

Lichun Zhu, Jinwen Hu, Weimin Li

Proceedings Volume 7012, Ground-based and Airborne Telescopes II; 70120U (2008) https://doi.org/10.1117/12.790609
Event: SPIE Astronomical Telescopes + Instrumentation, 2008, Marseille, France

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.

Citation Download Citation

Lichun Zhu, Jinwen Hu, and Weimin Li "The study on the scheme of dynamic measurement of the main active reflector for FAST", Proc. SPIE 7012, Ground-based and Airborne Telescopes II, 70120U (10 July 2008); https://doi.org/10.1117/12.790609

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