Optical fiber strain sensor with improved linearity range
First Claim
1. A strain sensor, comprising:
- a two-mode optical fiber constructed of materials producing an intermodal phase difference δ
φ
01 -δ
φ
11 of less than 0.17 radians when subjected to stress within a measurable range of the strain sensor;
light supply means for supplying light to a first end of said optical fiber; and
light intensity detection means for detecting light intensity of the point at a second end of said optical fiber.
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Accused Products
Abstract
A strain sensor is constructed from a two mode optical fiber. When the optical fiber is surface mounted in a straight line and the object to which the optical fiber is mounted is subjected to strain within a predetermined range, the light intensity of any point at the output of the optical fiber will have a linear relationship to strain, provided the following equation is less than 0.17 radians ##EQU1## where nco represents the refractive index of the core, k represents the wavenumber of the light, L represents the length of the optical fiber, S1 represents axial strain, V is ##EQU2## U is a solution to the eigenvalue equation of the optical fiber, vf represents the Poisson ratio, Pef represents the effective strain-optic coefficient of the optical fiber and nln represents ##EQU3## where K1 is the modified Bessel function of second kind of order/with argument given by
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Citations
4 Claims
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1. A strain sensor, comprising:
-
a two-mode optical fiber constructed of materials producing an intermodal phase difference δ
φ
01 -δ
φ
11 of less than 0.17 radians when subjected to stress within a measurable range of the strain sensor;light supply means for supplying light to a first end of said optical fiber; and light intensity detection means for detecting light intensity of the point at a second end of said optical fiber. - View Dependent Claims (2, 3)
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4. A strain sensor, comprising:
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a single mode optical fiber constructed of materials producing a phase of a fundamental mode δ
φ
01 of less than 0.17 radians when subjected to stress within a measurable range of the strain sensor;light supply means for supplying light to a first end of said optical fiber; and light intensity detection means for detecting light intensity of the point at a second end of said optical fiber.
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Specification