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Proceedings Paper

Fiber Optic Flexural Disk Microphone
Author(s): David A Brown; T. Hofler; S. L. Garrett
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Paper Abstract

A microphone consisting of a hollow cylinder whose flexible, circular endplates are bonded to pairs of flat spiral wound coils of optical fiber is described. When the endplate/disk is deformed due to a pressure difference, the outer and inner fiber coils experience opposite strains resulting in a "push-pull" optical path length difference which is detected in an all-fiber Michelson interferometer. The close proximity of the interferometric fiber coils, separated by the thin thermally conducting end plate, rejects thermal gradient induced signals. The addition of a second identical endplate and fiber coil pair at the opposite end of the cylinder doubles the acoustic sensitivity while canceling acceleration induced signals. The calculated and measured optical strain of a single plate, single coil sensor using static pressure, acoustic pressure, and acceleration are in good agreement and yield a sensitivity of 21 milliradians per Pascal per meter of optical fiber for an 8.0 cm diameter, 3.0 mm thick plate below its resonance frequency of 3 KHz.

Paper Details

Date Published: 1 February 1989
PDF: 11 pages
Proc. SPIE 0985, Fiber Optic and Laser Sensors VI, (1 February 1989); doi: 10.1117/12.948847
Show Author Affiliations
David A Brown, Naval Postgraduate School (United States)
T. Hofler, Naval Postgraduate School (United States)
S. L. Garrett, Naval Postgraduate School (United States)

Published in SPIE Proceedings Vol. 0985:
Fiber Optic and Laser Sensors VI
Ramon P. DePaula; Eric Udd, Editor(s)

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