Fused tension-based fiber grating pressure sensor
First Claim
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1. A pressure sensor, comprising:
- an optical fiber, having at least one pressure reflective element embedded therein, the pressure reflective element having a pressure reflection wavelength;
sensing means, fused to at least a portion of the fiber on opposite sides of the reflective elements, for holding the fiber on opposite axial sides of the reflective element and for adjusting the strain on the fiber in response to external pressure;
the reflective element having a predetermined amount of tension pre-stain; and
the sensing means being strained due to a change in pressure, the strain causing a change in the pressure reflection wavelength, and the change in the pressure reflection wavelength being indicative of the change in pressure.
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Abstract
A fused tension-based fiber grating pressure sensor includes an optical fiber having a Bragg grating impressed therein. The fiber is fused to tubes on opposite sides of the grating and an outer tube is fused to the tubes to form a chamber. The tubes and fiber may be made of glass. Light is incident on the grating and light is reflected from the grating at a reflection wavelength λ1. The grating is initially placed in tension as the pressure P increases, the tension on the grating reduced and the reflection wavelength shifts accordingly. A temperature grating may be used to measure temperature and allow for a temperature-corrected pressure measurement.
117 Citations
86 Claims
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1. A pressure sensor, comprising:
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an optical fiber, having at least one pressure reflective element embedded therein, the pressure reflective element having a pressure reflection wavelength;
sensing means, fused to at least a portion of the fiber on opposite sides of the reflective elements, for holding the fiber on opposite axial sides of the reflective element and for adjusting the strain on the fiber in response to external pressure;
the reflective element having a predetermined amount of tension pre-stain; and
the sensing means being strained due to a change in pressure, the strain causing a change in the pressure reflection wavelength, and the change in the pressure reflection wavelength being indicative of the change in pressure. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
a pair of end tubes being fused to at least a portion of the fiber on opposite sides of the reflective element; and
an outer tube being fused to the end tubes.
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3. The pressure sensor of claim 1, wherein the sensing means comprises a tube fused to at least a portion of the fiber on opposite axial sides of the reflective element.
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4. The pressure sensor of claim 1, wherein the reflective element is a Bragg grating.
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5. The pressure sensor of claim 3, wherein at least a portion of the tube has a cylindrical shape.
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6. The apparatus of claim 1 wherein the sensing means is made of a glass material.
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7. The apparatus of claim 1 wherein the sensing means has at least one axially extended region.
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8. The apparatus of claim 1 wherein the sensing means has at least one outer tapered axial end.
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9. The apparatus of claim 1 wherein the sensing means has at least one inner tapered axial end.
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10. The apparatus of claim 1, wherein the sensing means comprises a plurality of optical fibers encased in the tube.
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11. The apparatus of claim 1, wherein the fiber has a plurality of reflective elements embedded therein.
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12. The apparatus of claim 1, wherein the fiber has at least one pair of reflective elements and the fiber is doped with a rare-earth dopant at least between the pair of elements to form a fiber laser.
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13. The apparatus of claim 12, wherein the fiber laser lases at lasing wavelength which changes as pressure changes.
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14. The apparatus of claim 1, wherein at least a portion of the fiber is doped with a rare-earth dopant where the reflective element is located and the reflective element is configured to form a DFB fiber laser.
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15. The apparatus of claim 14, wherein the DFB fiber laser lases at a lasing wavelength which changes as force on the tube changes.
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16. The apparatus of claim 1, wherein the fiber has a temperature reflective element embedded therein disposed in thermal proximity to the pressure reflective element which has a temperature reflection wavelength that changes with temperature.
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17. The apparatus of claim 16, wherein the temperature reflective element is encased in the tube.
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18. The apparatus of claim 16, wherein the temperature reflection wavelength does not change in response to a change in the pressure wavelength due to a change in the pressure.
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19. The apparatus of claim 16, wherein the temperature reflection wavelength changes in response to a change in the pressure wavelength due to a change in the pressure at a different rate than the pressure wavelength changes due to a same change in pressure.
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20. The apparatus of claim 1, further comprising an outer housing, which contains the sensing means, the sensing means being suspended in the housing by suspension means.
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21. The apparatus of claim 18, wherein the suspension means comprises a fluid.
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22. The apparatus of claim 18, wherein the suspension means comprises spacers in a fluid.
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23. A pressure sensor, comprising:
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an optical fiber with at least one reflective element therein; and
a sensing element fused to at least a portion of the fiber on opposite sides of the reflective element. - View Dependent Claims (24, 25, 26)
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27. A method of making a pressure sensor comprising the steps of:
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obtaining an optical fiber with at least one reflective element therein; and
fusing a sensing element to at least a portion of the fiber on opposite sides of the reflective element. - View Dependent Claims (28, 29, 30)
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31. A pressure sensor, comprising:
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an optical waveguide comprising a pressure-sensitive reflective element; and
a first housing fused to a cladding of the optical waveguide at first and second axial locations to form a cavity around the pressure-sensitive reflective element, wherein the optical waveguide is pre-tensioned within the cavity. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56)
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57. A method for manufacturing a pressure sensor, comprising, in no particular order:
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providing an optical waveguide comprising a pressure-sensitive reflective element; and
fusing a first housing to a cladding of the optical waveguide at first and second axial locations to form a cavity around the pressure sensor; and
pre-tensioning the optical waveguide within the cavity. - View Dependent Claims (58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86)
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Specification