Microbend fiber-optic sensor
First Claim
1. A fiber-optic sensor for producing microbends in an optical fiber in response to variation of an environmental parameter, said optical fiber being embedded in a sheath made of a first material, said sheath being coated with a layer of a second material wherein said layer exhibits two lines of surface discontinuities according to a longitudinal direction of the fiber, said discontinuities being periodically distributed on each line at a distance d from each other and said lines being symmetrical according to the rotation axis of the fiber, but shifted on both sides of the rotation axis of the fiber whereby said first and second materials react in response to said environmental parameter in such a manner that a variation of said environmental parameter produces microbends of the same periodicity d as that of said discontinuities.
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Abstract
The invention relates to a fiber-optic detector and concerns more particularly a detector capable of producing microbends in an optical fiber in response to the variation of a physical quantity or of an environmental parameter. The sensor of the invention consists of an optical fiber provide with a sheath which is covered by a layer exhibiting periodic discontinuities. The sheath and its covering react to the variation of the parameter to be detected in such a manner as to produce microbends of the same periodicity as that of the discontinuities.
29 Citations
23 Claims
- 1. A fiber-optic sensor for producing microbends in an optical fiber in response to variation of an environmental parameter, said optical fiber being embedded in a sheath made of a first material, said sheath being coated with a layer of a second material wherein said layer exhibits two lines of surface discontinuities according to a longitudinal direction of the fiber, said discontinuities being periodically distributed on each line at a distance d from each other and said lines being symmetrical according to the rotation axis of the fiber, but shifted on both sides of the rotation axis of the fiber whereby said first and second materials react in response to said environmental parameter in such a manner that a variation of said environmental parameter produces microbends of the same periodicity d as that of said discontinuities.
- 14. A fiber-optical sensor for producing microbends in an optical fiber in response to a variation of an environmental parameter, wherein said optical fiber is embedded in a sheath made of a first material, said sheath being coated with a layer of a second material having periodic discontinuities in a longitudinal direction of the fiber optical sensor, said discontinuities being disposed asymmetrically with respect to a plane containing the fiber axis, said first and second materials reacting in response to a variation in said environmental parameter to produce microbends of the same periodicity as that of said discontinuities.
Specification