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Proceedings Paper

A CSO submillimeter active optics system
Author(s): Melanie Leong; Ruisheng Peng; Martin Houde; Hiroshige Yoshida; Richard Chamberlin; Thomas G. Phillips
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Paper Abstract

Active surface correction of the Caltech Submillimeter Observatory (CSO) primary mirror has been accomplished. The Dish Surface Optimization System (DSOS) has been designed and built to operate at the CSO, on Mauna Kea, Hawaii. The DSOS is the only active optics system of its kind in the world. There are 99 steel rod standoffs that interface the dish panels to its backing structure. Each standoff is now fitted with a heating/cooling assembly. Applying a controlled potential to each of the 99 assemblies adjusts the surface of the dish. Heating elongates and cooling shortens the standoffs, providing the push or pull on the primary's panel surface. The needed correction for each standoff, for a given elevation, is determined from prior holography measurements of the dish surface. Without the DSOS the optimum surface accuracy was 25-μm RMS, yielding a beam efficiency of 33% at the 350-μm-wavelength range. With the DSOS on, this has been improved to 10-μm RMS. The best beam efficiency obtained is 56%, with an average beam efficiency of 53%. The DSOS has been in operation on the CSO since February 2003. Observers using the SHARCII (a 384 pixel submillimeter high angular resolution camera) and the 850 GHz heterodyne receiver, have been able to detect new weak and/or distant objects including detection of an earth-massed planet in Fomalhaut with the help of this unique active optics system.

Paper Details

Date Published: 27 June 2006
PDF: 11 pages
Proc. SPIE 6275, Millimeter and Submillimeter Detectors and Instrumentation for Astronomy III, 62750P (27 June 2006); doi: 10.1117/12.672115
Show Author Affiliations
Melanie Leong, Caltech Submillimeter Observatory (United States)
Ruisheng Peng, Caltech Submillimeter Observatory (United States)
Martin Houde, Caltech Submillimeter Observatory (United States)
Hiroshige Yoshida, Caltech Submillimeter Observatory (United States)
Richard Chamberlin, Caltech Submillimeter Observatory (United States)
Thomas G. Phillips, California Institute of Technology (United States)

Published in SPIE Proceedings Vol. 6275:
Millimeter and Submillimeter Detectors and Instrumentation for Astronomy III
Jonas Zmuidzinas; Wayne S. Holland; Stafford Withington; William D. Duncan, Editor(s)

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