Fiber optic acoustic emission sensor

Patent 6097478 Issued on August 1, 2000. Estimated Expiration Date:

April 2, 2018. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.

Abstract Claims Description Full Text

Patent References

3051003

3056297

Transducer for converting acoustic energy directly into optical energy
Patent #: 4071753
Issued on: 01/31/1978
Inventor: Fulenwider , et al.

Fibre optic pressure sensor
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Inventor: Bucaro , et al.

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Patent #: 4360247
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Inventor: Beasley

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Inventor: Fuller

Microbending of optical fibers for remote force measurement
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Inventor: Whitten

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Inventors

Application

No. 053939 filed on 04/02/1998

US Classes:

356/35.5, By light interference detector (e.g., interferometer)356/477Using fiber or waveguide interferometer

Examiners

Primary: Kim, Robert H.
Assistant: Lee, Andrew H.

Attorney, Agent or Firm

Edwards; Robert J., Baraona; Robert C., Marich; Eric

International Class

G01B 009/02

Abstract

A fiber optic acoustic emission (FOAE) sensor particularly suitable for vibration sensing in a hostile environment has a pair of optical fibers each having an end face. In one embodiment, a hollow tube or core having opposite open ends receives the end faces of the optical fibers. Means are provided for fixing the optical fibers in the hollow core with the end faces facing each other and spaced by a distance from each other in the core. A signal processing unit is connected to the optical fibers for supplying light to, and for receiving light from, the optical fibers and for measuring variations in optical phase which result in changes in the light intensity due to vibrations of the hollow core. The hollow core is fixed in a resonant cylinder, and the resonant cylinder is fixed in a housing to complete the sensor. Other embodiments dispense with the need for the hollow tube or core and employ means for fixing the optical fibers within a precision hole, advantageously produced by electrical discharge machining (EDM) or similar processes, provided in the resonant cylinder. A system employing these embodiments of the FOAE sensor is also disclosed.

Other References

Murphy, Kent A. et al. "Acoustic Wave Response of the Extrinsic Fabry-Perot Interferometric (EFPI) Optical Fiber Sensor", Adaptive Structures and Material Systems-American Society of Mechanical Engineers, Aerospace Div., AD vol. 35, published by ASME, New York, NY 1993, pp. 395-39