Optical fiber sensor
First Claim
1. An optical fiber sensor comprising:
- a pulse-modulated, linearly polarized wideband optical source of the superluminescent diode type,a single-mode birefringent optical fiber sensor, the input face of which is coupled to the source, the axis of polarization of the source being aligned with a neutral axis of the fiber;
at least one device, for creating polarization coupling points, that is placed on the optical fiber and, in being subjected to a stress, creates a coupling point in the fiber;
polarization means that are coupled to the output face of the fiber to align the polarizations of the waves transmitted by the fiber,a spectroscopic analysis device coupled to the output of the polarization means, to analyze the radiation transmitted and to form the transmission function of the sensor,and processing means which, through the transmission function, extract the measurement of strain corresponding to the coupling point.
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Abstract
The disclosed optical fiber sensor uses the effect of variation in the birefringence in a birefringent optical fiber as a function of the stresses and of the temperature. It has a linearly polarized, wide-spectrum source coupled to a polarizing-preserving single-mode optical fiber, along one of its neutral axes, devices capable of inducing coupling points being distributed along this fiber. A polarizer at 45° with respect to the neutral axes of the fiber is placed at output of this sensor fiber. The output radiation is analyzed by spectroscopy, for example in a scanning Michelson interferometer associated with a detector. The detection by the interferometer enables the identification of the devices that are subjected to stresses. The same type of device may be used for the simultaneous detection of the stresses and/or the temperatures. The disclosed device can be applied notably to the monitoring and supervision of any installation in which strains have to be detected.
57 Citations
12 Claims
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1. An optical fiber sensor comprising:
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a pulse-modulated, linearly polarized wideband optical source of the superluminescent diode type, a single-mode birefringent optical fiber sensor, the input face of which is coupled to the source, the axis of polarization of the source being aligned with a neutral axis of the fiber; at least one device, for creating polarization coupling points, that is placed on the optical fiber and, in being subjected to a stress, creates a coupling point in the fiber; polarization means that are coupled to the output face of the fiber to align the polarizations of the waves transmitted by the fiber, a spectroscopic analysis device coupled to the output of the polarization means, to analyze the radiation transmitted and to form the transmission function of the sensor, and processing means which, through the transmission function, extract the measurement of strain corresponding to the coupling point. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
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Specification