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A 100-m Fabry–Pérot Cavity with Automatic Alignment Controls for Long-Term Observations of Earth’s Strain
- Source :
- Technologies, Vol 2, Iss 3, Pp 129-142 (2014), Technologies, Volume 2, Issue 3, Pages 129-142
- Publication Year :
- 2014
- Publisher :
- MDPI AG, 2014.
-
Abstract
- We have developed and built a highly accurate laser strainmeter for geophysical observations. It features the precise length measurement of a 100-m optical cavity with reference to a stable quantum standard. Unlike conventional laser strainmeters based on simple Michelson interferometers that require uninterrupted fringe counting to track the evolution of ground deformations, this instrument is able to determine the absolute length of a cavity at any given time. The instrument offers advantage in covering a variety of geophysical events, ranging from instantaneous earthquakes to crustal deformations associated with tectonic strain changes that persist over time. An automatic alignment control and an autonomous relocking system have been developed to realize stable performance and maximize observation times. It was installed in a deep underground site at the Kamioka mine in Japan, and an effective resolution of 2 × (10−8 − 10−7) m was achieved. The regular tidal deformations and co-seismic strain changes were in good agreement with those from a theoretical model and a co-located conventional laser strainmeter. Only the new instrument was able to record large strain steps caused by a nearby large earthquake because of its capability of absolute length determination.
- Subjects :
- business.industry
lcsh:T
optical cavity alignment
earthquake monitoring
laser strainmeter
Ranging
Strainmeter
Geodesy
Laser
lcsh:Technology
law.invention
Physics::Geophysics
Tectonics
Length measurement
Optics
law
Optical cavity
Astronomical interferometer
absolute distance determination
business
Geology
Fabry–Pérot interferometer
Subjects
Details
- Language :
- English
- ISSN :
- 22277080
- Volume :
- 2
- Issue :
- 3
- Database :
- OpenAIRE
- Journal :
- Technologies
- Accession number :
- edsair.doi.dedup.....79678d2d38dbd92bb48f850b528876a2