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Proceedings Paper

Measuring transmission and forces from observatory equipment vibration
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Paper Abstract

We describe measurements of both the vibration forces imparted by various types of observatory equipment, and the transmission of these forces through the soil, foundations and telescope pier. These are key uncertainties both in understanding how to mitigate vibration at existing observatories and for developing a vibration budget in the design of future observatories such as the Thirty Meter Telescope. Typical vibration surveys have measured only the resulting motion (acceleration); however, this depends on both the source and the system being excited (for example, isolating equipment results in less force being transmitted, but greater motion of the equipment itself). Instead, here we (a) apply a known force input to the pier from a shaker and measure the response at different locations, and (b) use isolator properties combined with measured acceleration to infer the forces applied by various equipment directly. The soil foundation and pier transmission can then be combined with a finite element model based vibration transmission analysis to estimate the optical consequences. Estimates of plausible source levels supports the development of a vibration budget for TMT that allocates allowable forces to the sources of vibration; this is described in a companion paper.

Paper Details

Date Published: 22 July 2014
PDF: 8 pages
Proc. SPIE 9145, Ground-based and Airborne Telescopes V, 91454G (22 July 2014); doi: 10.1117/12.2057206
Show Author Affiliations
Hugh Thompson, Thirty Meter Telescope Observatory Corp. (United States)
Doug G. MacMartin, Thirty Meter Telescope Observatory Corp. (United States)
California Institute of Technology (United States)
Peter W. G. Byrnes, National Research Council Canada (Canada)
Daigo Tomono, Subaru Telescope, National Astronomical Observatory of Japan (United States)
Hiroshi Terada, Subaru Telescope, National Astronomical Observatory of Japan (United States)

Published in SPIE Proceedings Vol. 9145:
Ground-based and Airborne Telescopes V
Larry M. Stepp; Roberto Gilmozzi; Helen J. Hall, Editor(s)

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