Fiber optic sensing device and method of making and operating the same
First Claim
1. A fiber optic sensor cable, composing:
- a core having a grating with a quasiperiodic modulation of index of refraction, the grating composing;
a plurality of grating element blocks having a refractive index na and a fiber length d(na) or a refractive index nb and a fiber length d(nb), arranged in a quasiperiodic sequence, wherein the quasiperiodic sequence is defined by the equation Sj={Sj-1,Sj-2} for j values greater than two, wherein S1=na and S2=na nb anda cladding disposed circumferentially about the core.
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Abstract
In accordance with one exemplary embodiment the invention provides a multi-parameter fiber optic sensing system with an aperiodic sapphire fiber grating as sensing element for simultaneous temperature, strain, NOx, CO, O2 and H2 gas detection. The exemplary sensing system includes an aperiodic fiber grating with an alternative refractive index modulation for such multi-function sensing and determination. Fabrication of such quasiperiodic grating structures can be made with point-by-point UV laser inscribing, diamond saw micromachining, and phase mask-based coating and chemical etching methods. In the exemplary embodiment, simultaneous detections on multi-parameter can be distributed, but not limited, in gas/steam turbine exhaust, in combustion and compressor, and in coal fired boilers etc. Advantageously, the mapping of multiple parameters such as temperature, strain, and gas using sapphire aperiodic gratings improves control and optimization of such systems directed to improve efficiency and output and reduce emissions.
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Citations
27 Claims
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1. A fiber optic sensor cable, composing:
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a core having a grating with a quasiperiodic modulation of index of refraction, the grating composing; a plurality of grating element blocks having a refractive index na and a fiber length d(na) or a refractive index nb and a fiber length d(nb), arranged in a quasiperiodic sequence, wherein the quasiperiodic sequence is defined by the equation Sj={Sj-1,Sj-2} for j values greater than two, wherein S1=na and S2=na nb and a cladding disposed circumferentially about the core. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A fiber optic sensing device, comprising:
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a fiber core comprising a grating with a quasiperiodic modulation of index of refraction, wherein the grating comprises a plurality of grating element blocks having a refractive index na or a refractive index nb, arranged in a quasiperiodic sequence, wherein the quasiperiodic sequence is defined by the equation Sj={Sj-1,Sj-2} for j values greater than two, wherein S1=na and S2=na nb; a light source configured to illuminate the core; and a detector system configured to estimate at least one parameter based upon at least one diffraction peak generated from the plurality of grating element blocks. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24)
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25. A fiber optic sensor cable, comprising:
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a core; and a cladding disposed circumferentially about the core; wherein the core comprises an aperiodic grating comprising an aperiodic sequence of blocks na and nb, wherein na having a first index of refraction and nb having a second index of refraction different from the first index of refraction, wherein the aperiodic sequence is a Fibonacci sequence.
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26. A fiber optic sensor cable, comprising:
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a core; and a cladding disposed circumferentially about the core; wherein the core comprises an aperiodic grating comprising an aperiodic sequence of blocks na and nb, wherein na having a first index of refraction and nb having a second index of refraction different from the first index of refraction, wherein the aperiodic sequence is defined by the equation Sj{Sj-1,Sj-2} for j values greater than two, wherein S1=na and S2 =nanb. - View Dependent Claims (27)
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Specification