An optical fiber infrasound sensor: a new lower limit on atmospheric pressure noise between 1 and 10 Hz.
A new distributed sensor for detecting pressure variations caused by distant sources has been developed. The instrument reduces noise due to air turbulence in the infrasound band by averaging pressure along a line by means of monitoring strain in a long tubular diaphragm with an optical fiber interferometer. Above 1 Hz, the optical fiber infrasound sensor (OFIS) is less noisy than sensors relying on mechanical filters. Records collected from an 89-m-long OFS indicate a new low noise limit in the band from 1 to 10 Hz. Because the OFIS integrates pressure variations at light-speed rather than the speed of sound, phase delays of the acoustical signals caused by the sensor are negligible. Very long fiber-optic sensors are feasible and hold the promise of better wind-noise reduction than can be achieved with acoustical-mechanical systems.
Zumberge
Mark A
MA
The Cecil and Ida Green Institute of Geophysics and Planetary Physics, Scripps Institution of Oceanography, University of California-San Diego, La Jolla, California 92093-0225, USA.
Berger
Jonathan
J
Hedlin
Michael A H
MA
Husmann
Eric
E
Nooner
Scott
S
Hilt
Richard
R
Widmer-Schnidrig
Rudolf
R
D001274:Atmospheric Pressure; D005336:Fiber Optic Technology / Q000295:instrumentation*; D008962:Models, Theoretical; D009622:Noise; D055100:Optical Fibers