Fiber optic strain gauge patch
First Claim
1. A fiber optic strain gauge patch comprising:
- (a) a first layer of protective carrier material;
(b) an optical fiber having a first end and a second end, formed in a plurality of loops, and disposed onto the first layer of protective carrier material;
(c) a first reflective marker in the optical fiber in proximity to the first end of the optical fiber;
(d) a second reflective marker in the optical fiber in proximity to the second end of the optical fiber; and
(e) a second layer of protective carrier material disposed onto the optical fiber,wherein the first and second layers of protective carrier material hold the optical fiber in position with respect to the first and second layers of protective carrier material.
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Accused Products
Abstract
A fiber optic sensor for measuring strain on and within structures. The sensor includes an optical fiber, two reflective markers, and two thin layers of carrier material. The optical fiber is looped multiple times within the two thin layers of the carrier material. The optical signal circulates multiple times through the sensing region, as it is travels through the multiple loops of optical fiber within the carrier layers. The fiber optic sensor can be embedded within a structure, as that structure is being fabricated, or it can be attached onto a preexisting structure. An optical signal generated from a source such as a laser is input into one end of the optical fiber. The signal is reflected at reflective markers at predetermined positions in the optical fiber. The time delay of the signals received back is then analyzed to calculate the strain in the structure.
88 Citations
49 Claims
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1. A fiber optic strain gauge patch comprising:
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(a) a first layer of protective carrier material; (b) an optical fiber having a first end and a second end, formed in a plurality of loops, and disposed onto the first layer of protective carrier material; (c) a first reflective marker in the optical fiber in proximity to the first end of the optical fiber; (d) a second reflective marker in the optical fiber in proximity to the second end of the optical fiber; and (e) a second layer of protective carrier material disposed onto the optical fiber, wherein the first and second layers of protective carrier material hold the optical fiber in position with respect to the first and second layers of protective carrier material. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A system for measuring strain comprising:
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(a) a fiber optic strain gauge patch comprising a first layer and a second layer of protective carrier material, an optical fiber having a first end and a second end, formed in a plurality of loops, and disposed onto the first layer of protective carrier material, first and second reflective markers on the optical fiber in proximity to the first and second ends, respectively, of the optical fiber, wherein the first and second layers of protective carrier material hold the optical fiber in position with respect to the first and second layers of protective carrier material; (b) a monitor connected to the optical fiber in the fiber optic strain gauge patch by a connecting optical fiber, said monitor comprising a light source, a delay generator, a fast rise-time photodetector and a fiber optic splitter; (c) means for analyzing data derived from optical signals reflected by the reflective markers to calculate strain in the optical fiber. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A method for making a fiber optic strain gauge patch comprising:
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(a) preparing a first and a second layer of protective carrier material; (b) preparing an optical fiber having a first end and a second end, and having a first reflective marker in proximity to the first end and a second reflective marker in proximity to the second end; (c) placing the optical fiber in multiple loops on the first layer of protective carrier material; (d) encasing the first end of the optical fiber in protective flexible cover; (e) placing the second layer of protective carrier material over the optical fiber; and (f) pressing the first and second layers of protective carrier material against each other at a pressure ranging from about 0 psi to about 20 psi. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A method for measuring strain in a structure comprising:
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(a) providing a fiber optic strain gauge patch having a first layer of protective carrier material, multiple loops of an optical fiber with a first end, a second end, a first reflective marker in proximity to the first end, a second reflective marker in proximity to the second end, and a second layer of protective carrier material, said first and second layers of protective materials covering and enclosing said multiple loops of the optical fiber; (b) optically connecting the first end of the optical fiber to a time domain reflectometer having a light source, a delay generator, a fast rise-time photo-detector and a fiber optic splitter; (c) using the optical time domain reflectometer to input a first light pulse into the first end of the optical fiber; (d) using the optical time delay reflectometer to detect light pulses reflected by the first and second reflective markers; (e) measuring the time delay between light pulses reflected by the first reflective marker and light pulses reflected by the second reflective marker; and (f) calculating the strain in the structure from the time delay between light pulses. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38, 39, 40, 41)
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42. A fiber optic strain gauge patch for installation in a composite material comprising:
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(a) an optical fiber having a first end and a second end, disposed in loops onto a first layer of protective carrier material; (b) a first reflective marker in the optical fiber in proximity to the first end of the optical fiber; (c) a second reflective marker in the optical fiber in proximity to the second end of the optical fiber; and (d) a second layer of protective carrier material disposed onto the optical fiber, wherein the first and second layers of protective carrier material hold the optical fiber in position with respect to the first and second layers of protective carrier material, and wherein the protective carrier material is selected such that the curing characteristics of the carrier material match the curing characteristics of the composite material sufficiently such that the carrier material can be cured as the composite material is cured. - View Dependent Claims (43, 44, 45, 46, 47, 48, 49)
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Specification