Measuring transmission and forces from observatory equipment vibration

From National Research Council Canada

DOIResolve DOI: https://doi.org/10.1117/12.2057206
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Name affiliation
  1. National Research Council of Canada. National Science Infrastructure
FormatText, Article
Proceedings titleGround-Based and Airborne Telescopes V
Series titleProceedings of SPIE; no. 9145
ConferenceGround-Based and Airborne Telescopes V, June 22-27, 2014
ISSN0277-786X
1996-756X
ISBN9780819496133
Article number91454G
SubjectAirborne telescopes; Equipment; Finite element method; Observatories; Optical telescopes; Extremely Large Telescopes; Soil foundation; Thirty Meter Telescope; TMT; Vibration; Vibration forces; Vibration transmission; Vibration analysis
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.
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PublisherSPIE
LanguageEnglish
Peer reviewedYes
NPARC number21275587
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