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A Caltech Submillimeter Observatory Active Optics System

Leong, Melanie and Peng, Ruisheng and Yoshida, Hiroshige and Chamberlin, Richard and Phillips, Thomas G. (2009) A Caltech Submillimeter Observatory Active Optics System. In: Submillimeter astrophysics and technology : a symposium honoring Thomas G. Phillips. ASP Conference Series. No.417. Astronomical Society of the Pacific Conference Series , San Francisco, CA, pp. 131-136. ISBN 978-1-58381-714-8.

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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 SHARC-II (Dowell et al. 2003; 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 with the help of this unique active optics system.

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Additional Information:© 2009 Astronomical Society of the Pacific. The DSOS was researched, prototyped, designed, and built through a grant from the National Science Foundation, Grant Number AST 99-80846.
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Series Name:ASP Conference Series
Issue or Number:417
Record Number:CaltechAUTHORS:20100914-084943269
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:19928
Deposited By: Tony Diaz
Deposited On:16 Sep 2010 22:38
Last Modified:03 Oct 2019 02:03

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