Fiber optic sensor having a multicore optical fiber and an associated sensing method
First Claim
1. A fiber optic sensor for measuring strain in a workpiece independent of variations in temperature to which the workpiece is subjected, the fiber optic sensor comprising:
- a multicore optical fiber comprising;
first and second optical cores adapted to transmit optical signals having first and second predetermined wavelengths, respectively, in a single spatial mode, wherein the first and second predetermined wavelengths are different, and wherein said first and second optical cores include a respective Bragg grating at the same relative spatial location which is adapted to reflect optical signals having the first and second predetermined wavelengths, respectively; and
a cladding layer surrounding each of said first and second optical cores;
first and second optical sources for generating optical signals having first and second predetermined wavelengths, respectively, said first and second optical sources being coupled to said first and second optical cores of said multicore optical fiber, respectively, for transmitting the optical signals therethrough;
first and second detectors, coupled to said first and second optical cores of said multicore optical fiber, respectively, for detecting optical signals reflected by the respective Bragg grating of said first and second optical cores; and
strain determining means, operably connected to said first and second detectors, for determining the strain imparted to the workpiece, independent of variations in the temperature to which the workpiece is subjected, based upon the difference between the respective wavelengths of the optical signals detected by said first and second detectors and the first and second predetermined wavelengths, respectively.
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Abstract
A fiber optic sensor and associated sensing method includes a multicore optical fiber having first and second optical cores adapted to transmit optical signals having first and second predetermined wavelengths, respectively, in a single spatial mode. The first and second optical cores each include a respective Bragg grating adapted to reflect optical signals having the first and second predetermined wavelengths, respectively. Based upon the differences between the respective wavelengths of the optical signals reflected by the respective Bragg gratings and the first and second predetermined wavelengths, a predetermined physical phenomena to which the workpiece is subjected can be determined. For example, the fiber optic sensor can include strain determining means for determining the strain imparted to the workpiece. Alternatively, the fiber optic sensor can include temperature determining means for determining the temperature to which the workpiece is subjected. Further, the fiber optic sensor can include both strain determining means and temperature determining means for simultaneously determining the strain and temperature to which a workpiece is subjected. The fiber optic sensor also includes calibration means for measuring the predetermined physical phenomena, independent of variations in other physical phenomena.
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Citations
20 Claims
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1. A fiber optic sensor for measuring strain in a workpiece independent of variations in temperature to which the workpiece is subjected, the fiber optic sensor comprising:
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a multicore optical fiber comprising; first and second optical cores adapted to transmit optical signals having first and second predetermined wavelengths, respectively, in a single spatial mode, wherein the first and second predetermined wavelengths are different, and wherein said first and second optical cores include a respective Bragg grating at the same relative spatial location which is adapted to reflect optical signals having the first and second predetermined wavelengths, respectively; and a cladding layer surrounding each of said first and second optical cores; first and second optical sources for generating optical signals having first and second predetermined wavelengths, respectively, said first and second optical sources being coupled to said first and second optical cores of said multicore optical fiber, respectively, for transmitting the optical signals therethrough; first and second detectors, coupled to said first and second optical cores of said multicore optical fiber, respectively, for detecting optical signals reflected by the respective Bragg grating of said first and second optical cores; and strain determining means, operably connected to said first and second detectors, for determining the strain imparted to the workpiece, independent of variations in the temperature to which the workpiece is subjected, based upon the difference between the respective wavelengths of the optical signals detected by said first and second detectors and the first and second predetermined wavelengths, respectively. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A fiber optic sensor for measuring a temperature to which a workpiece is subjected independent of variations in strain imparted to the workpiece, the fiber optic sensor comprising:
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a multicore optical fiber comprising; first and second optical cores adapted to transmit optical signals having first and second predetermined wavelengths, respectively, in a single spatial mode, wherein the first and second predetermined wavelengths are different, and wherein said first and second optical cores include a respective Bragg grating at the same relative spatial location which is adapted to reflect optical signals having the first and second predetermined wavelengths, respectively; and a cladding layer surrounding each of said first and second optical cores; first and second optical sources for generating optical signals having first and second predetermined wavelengths, respectively, said first and second optical sources being coupled to said first and second optical cores of said multicore optical fiber, respectively, for transmitting the optical signals therethrough; first and second detectors, coupled to said first and second optical cores of said multicore optical fiber, respectively, for detecting optical signals reflected by the respective Bragg grating of said first and second optical cores; and temperature determining means, operably connected to said first and second detectors, for determining the temperature to which the workpiece is subjected, independent of variations in the strain imparted to the workpiece, based upon the difference between the respective wavelengths of the optical signals detected by said first and second detectors and the first and second predetermined wavelengths, respectively. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A method of sensing a predetermined phenomena to which a workpiece is subjected, independent of other phenomena to which the workpiece is subjected, the method comprising the steps of:
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generating first and second optical signals having first and second predetermined wavelengths, respectively, wherein the first and second predetermined wavelengths are different; coupling the first and second optical signals to first and second optical cores, respectively, of a multicore optical fiber; transmitting the first and second optical signals in a single spatial mode through the first and second optical cores, respectively, of the multicore optical fiber; reflecting the optical signals transmitted by the first and second optical cores by first and second Bragg gratings defined by the first and second optical cores, respectively, at the same relative spatial location to thereby create first and second resonance signals, respectively; detecting the first and second resonance signals reflected by the respective Bragg gratings of the first and second optical cores, respectively; and determining the magnitude of the predetermined phenomena to which the workpiece is subjected, independent of other phenomena to which the workpiece is subjected, based upon the difference between the respective wavelengths of the first and second resonance signals and the first and second predetermined wavelengths, respectively. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification