An Optical Fiber Infrasound Sensor

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An Optical Fiber Infrasound Sensor
Institute of Geophysics and Planetary
Physics Scripps Institution of Oceanography Univer
sity of California, San Diego

• M. Zumberge, J. Blum, K. Walker,
• J. Berger, M. Dzieciuch, M. Hedlin

Presented to Infrasound Technology Workshop
29 Oct 2003
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Old Infrasound Technology

• Basic design is a single-point microbarograph
  connected to a series of pipes for spatial
  filtering

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New Sensor Concept

• A long, compliant, sealed tube deforms as
  pressure changes
• An optical fiber wrapped around the tube senses
  the deformation

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line-integrated average
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Instrument Constructionand Installation
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Effect of geometry on response

• linear sensors depend on length, signal ?, and
  arrival azimuth
• circular sensors depend on diameter and signal
  ?

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Conclusions

• The OFIS is comparable to the best pipe array
  from the microbarom band up to 1 Hz
• Above 1 Hz, the OFIS is significantly quieter
• The OFIS is also a very good microphone
• The sensor can be made significantly longer to
  average over a larger region
• An array of OFISs will be capable of determining
  source azimuth
• Rapidly deployable, above-ground OFISs are viable
  sensors for infrasound source monitoring
• Some TEDs (Technical Engineering Details) remain
  to be solved before we can deploy OFISs routinely
  or widely

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Acknowledgements

• Funding for research and development of the OFIS
  has been provided by
• Scripps Institution of Oceanography
• Kinemetrics Corporation
• The Green Foundation for Earth Science
• The Defense Threat Reduction Agency
• DARPA
• SAIC