Structural monitoring system using fiber optics
First Claim
1. A method of monitoring a physical movement occurring at any point between spaced points on a structure including the steps of:
- (a) attaching with attachment means at least one optical fiber continuously to said structure to extend from at least one of the spaced points to the other and thereby engage all points along the structure between said spaced points so that physical movement of the structure between said spaced points will result in physical movement of the optical fiber;
(b) passing a first light signal into said optical fiber; and
(c) detecting reflection changes in said first light signal resulting from said physical movement to thereby provide an indication that a physical movement has taken place and a indication of the location and magnitude of said movement.
1 Assignment
0 Petitions
Accused Products
Abstract
An optical fiber is securely and continuously fastened to a structure such as a pipeline, offshore platform, bridge, building, dam or even a natural object. A light signal is passed into one end of the optical fiber. Any physical movement of the structure, or sectional movements along the optical fiber path, such as deflection, bending, displacement (changes in linear uniformity) or fracture of the structure will necessarily affect the optical fiber. As a consequence, detectable changes will occur in the "electro-optic signature" (for measurements made at the input end of the optical fiber) or in the light signal transmission (for measurements made at the opposite end of the optical fiber). Such measurements made at the input include reflections resulting from Rayleigh back-scattering and can be periodically or continuously made to determine the magnitude and location of the aforementioned physical movements of the structure. In addition, by utilizing additional optical fibers, the direction and rate, i.e., dynamics, of such physical movements can be determined. The optical fiber itself can be used as a communication link for the transmission of data and voice.
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Citations
11 Claims
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1. A method of monitoring a physical movement occurring at any point between spaced points on a structure including the steps of:
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(a) attaching with attachment means at least one optical fiber continuously to said structure to extend from at least one of the spaced points to the other and thereby engage all points along the structure between said spaced points so that physical movement of the structure between said spaced points will result in physical movement of the optical fiber; (b) passing a first light signal into said optical fiber; and (c) detecting reflection changes in said first light signal resulting from said physical movement to thereby provide an indication that a physical movement has taken place and a indication of the location and magnitude of said movement. - View Dependent Claims (2)
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3. A method of determining the locations of physical movement occurring along a continuum of points between spaced points on a structure, said method including the steps of:
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(a) attaching with attachment means at least one optical fiber continuously to said structure to extend from at least one of the spaced points to the other and thereby engage all points along the structure between said spaced points so that physical movement of the structure between said spaced points will result in physical movement of said optical fiber; (b) passing a first light signal into said optical fiber; and (c) continuously detecting individual multiple light reflections in said fiber along the continuum of points between spaced points to identify points along the structure at which a physical movement has taken place and to provide an indication of the magnitude of all such movements.
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4. An apparatus for monitoring a physical movement between spaced points on a structure including, in combination:
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(a) at least one optical fiber; (b) attachment means between said optical fiber and said structure for attaching said optical fiber continuously to said structure to extend from at least one of the spaced points to the other and thereby directly engage all points along the structure between said spaced points so that physical movement of the structure between said spaced points will result in physical movement of the optical fiber; (c) means for passing a first light signal into said optical fiber; (d) means for detecting and indicating reflection changes in said first light signal as a consequence of said physical movement; and
,(e) means responsive to said reflection changes for indicating the location and magnitude of said physical movement. - View Dependent Claims (5, 6, 7, 8)
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9. An apparatus for monitoring a physical movement between spaced points on a structure including, in combination:
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(a) at least on optical fiber; (b) means for attaching said optical fiber continuously to said structure to extend from at least one of the spaced points to the other and thereby engage all points along the structure between said spaced points; (c) means for passing a first light signal into said optical fiber; (d) means for detecting and indicating reflection changes in said first light signal as a consequence of said physical movement; (e) means responsive to said reflection changes for indicating the location and magnitude of said physical movement; (f) at least one additional optical fiber secured to said structure along portions of the structure spaced from said one optical fiber; (g) means for passing a second light signal into said additional optical fiber; (h) means for detecting changes in said second light signal resulting from said physical movement of the structure; and (j) means for comparing the changes in said first light signal with the changes in said second light signal to thereby enable the direction of said physical movement to be determined.
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10. An apparatus for monitoring a physical movement between spaced points on a structure including, in combination:
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(a) at least one optical fiber; (b) attachment means between said optical fiber and said structure for attaching said optical fiber continuously to said structure to extend from at least one of the spaced points to the other and thereby engage all points along the structure between said spaced points so that physical movement of said structure between said spaced points will result in physical movement of said optical fiber; (c) means for passing a first light signal into said optical fiber; (d) means for detecting and indicating reflection changes in said first light signal as a consequence of said physical movement; and (e) means responsive to said reflection changes for indicating the location and magnitude of said physical movement; (f) said optical fiber including a core and surrounding cladding, said cladding having an index of refraction different from the index of refraction of said core, said first light signal passing through said core being substantially retained in the core by internal reflections from the interface of said core and cladding so long as the index of refraction of said cladding is not changes;
a sheath surrounding said cladding, said sheath having a coating of fixed particulate material uniformly spread over its interior wall surface in intimate engagement with the outer surface of said cladding, said particulate material having a diameter of from 5 to 23 microns, said particulate material radially moving into and distorting the homogeneity of at least a portion of said cladding whenever said sheath, cladding and core are subject to tension as a result of said physical movement of said structure attached to said fiber, the distortion resulting in a change in the index of refraction of the cladding such that some light is permitted to escape from said core and cladding at the location of said physical movement thereby generating Rayleigh back scattering reflection changes in said light signal.
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11. A method of monitoring a physical movement occurring at any point between spaced points on a structure including the steps of:
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(a) attaching at least one optical fiber continuously to said structure to extend from at least one of the spaced points to the other and thereby engage all points along the structure between said spaced points; (b) passing a first light signal into said optical fiber; (c) detecting reflection changes in said first light signal resulting from said physical movement to thereby provide an indication that a physical movement has taken place and an indication of the location and magnitude of said movement; (d) attaching at least one additional optical fiber to said structure extending along portions of the structure spaced from said one optical fiber; (e) passing a second light signal into said additional optical fiber; (f) detecting changes in said second light signal resulting from said physical movement of the structure; and (g) comparing the changes in said first light signal with the changes in said second light signal to thereby enable the direction of said physical movement to be determined.
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Specification