1. An Optical Fiber Infrasound Sensor
Institute of Geophysics and Planetary Physics
Scripps Institution of Oceanography
University of California, San Diego
An Optical Fiber Infrasound Sensor
M. Zumberge, J. Blum, K. Walker,
J. Berger, M. Dzieciuch, M. Hedlin
Presented to Infrasound Technology Workshop Oct 2003

2. Old Infrasound Technology
Basic design is a single-point microbarograph connected to a series of pipes for spatial filtering

3. New Sensor Concept
A long, compliant, sealed tube deforms as pressure changes
An optical fiber wrapped around the tube senses the deformation

4. line-integrated average

6. Instrument Construction and Installation

24. Effect of geometry on response
linear sensors depend on length, signal , and arrival azimuth
circular sensors depend on diameter and signal 

26. 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

27. 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