Extrinsic fiber optic displacement sensors and displacement sensing systems
Abstract
An extrinsic Fizeau fiber optic sensor comprises a single-mode fiber, used as an input/output fiber, and a multimode fiber, used purely as a reflector, to form an air gap within a silica tube that acts as a Fizeau cavity. The Fresnel reflection from the glass/air interface at the front of the air gap (reference reflection) and the reflection from the air/glass interface at the far end of the air gap (sensing reflection) interfere in the input/output fiber. The two fibers are allowed to move in the silica tube, and changes in the air gap length cause changes in the phase difference between the reference reflection and the sensing reflection. This phase difference is observed as changes in intensity of the light monitored at the output arm of a fused biconical tapered coupler. The extrinsic Fizeau fiber optic sensor behaves identically whether it is surface mounted or embedded, which is unique to the extrinsic sensor in contrast to intrinsic Fabry-Perot sensors. The sensor may be modified to provide a quadrature phase shift extrinsic Fizeau fiber optic sensor for the detection of both the amplitude and the relative polarity of dynamically varying strain. The quadrature light signals may be generated by eithermore »
- Inventors:
- Issue Date:
- Research Org.:
- Virginia Polytech Inst/St Univ
- OSTI Identifier:
- 5051543
- Patent Number(s):
- 5301001
- Application Number:
- PPN: US 7-834674
- Assignee:
- Center For Innovative Technology, Herndon, VA (United States)
- DOE Contract Number:
- AC21-89MC25159
- Resource Type:
- Patent
- Resource Relation:
- Patent File Date: 12 Feb 1992
- Country of Publication:
- United States
- Language:
- English
- Subject:
- 47 OTHER INSTRUMENTATION; DISPLACEMENT GAGES; DESIGN; MULTIPLEXERS; OPTICAL FIBERS; SILICON OXIDES; CHALCOGENIDES; ELECTRONIC EQUIPMENT; EQUIPMENT; FIBERS; MEASURING INSTRUMENTS; OXIDES; OXYGEN COMPOUNDS; SILICON COMPOUNDS; 440800* - Miscellaneous Instrumentation- (1990-)
Citation Formats
Murphy, K A, Gunther, M F, Vengsarkar, A M, and Claus, R O. Extrinsic fiber optic displacement sensors and displacement sensing systems. United States: N. p., 1994.
Web.
Murphy, K A, Gunther, M F, Vengsarkar, A M, & Claus, R O. Extrinsic fiber optic displacement sensors and displacement sensing systems. United States.
Murphy, K A, Gunther, M F, Vengsarkar, A M, and Claus, R O. Tue .
"Extrinsic fiber optic displacement sensors and displacement sensing systems". United States.
@article{osti_5051543,
title = {Extrinsic fiber optic displacement sensors and displacement sensing systems},
author = {Murphy, K A and Gunther, M F and Vengsarkar, A M and Claus, R O},
abstractNote = {An extrinsic Fizeau fiber optic sensor comprises a single-mode fiber, used as an input/output fiber, and a multimode fiber, used purely as a reflector, to form an air gap within a silica tube that acts as a Fizeau cavity. The Fresnel reflection from the glass/air interface at the front of the air gap (reference reflection) and the reflection from the air/glass interface at the far end of the air gap (sensing reflection) interfere in the input/output fiber. The two fibers are allowed to move in the silica tube, and changes in the air gap length cause changes in the phase difference between the reference reflection and the sensing reflection. This phase difference is observed as changes in intensity of the light monitored at the output arm of a fused biconical tapered coupler. The extrinsic Fizeau fiber optic sensor behaves identically whether it is surface mounted or embedded, which is unique to the extrinsic sensor in contrast to intrinsic Fabry-Perot sensors. The sensor may be modified to provide a quadrature phase shift extrinsic Fizeau fiber optic sensor for the detection of both the amplitude and the relative polarity of dynamically varying strain. The quadrature light signals may be generated by either mechanical or optical means. A plurality of the extrinsic sensors may connected in cascade and multiplexed to allow monitoring by a single analyzer. 14 figures.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Tue Apr 05 00:00:00 EDT 1994},
month = {Tue Apr 05 00:00:00 EDT 1994}
}