US 9,310,273 B2 · Optical fibre sensor interrogation system

Abstract

A monitoring system for monitoring a plurality of fiber Bragg gratings in an optical fiber, each fiber Bragg grating being sensitive to a different wavelength of light. The system comprises a broadband source for illuminating the optical fiber; at least one optical interferometer; light feeding means for feeding to an input of the interferometer light reflected from the fiber Bragg gratings, and a processor for processing the output from the interferometer to determine the wavelength of the reflected light. The light feeding means comprise a wavelength division multiplexer operable to separate light received from the optical fiber into a plurality of wavelengths, each associated with one of the fiber Bragg gratings and/or a time division mulitplexer operable to separate light received from the optical fiber into in a time separated series.

Claims12

Dependent claims

A monitoring system for monitoring a plurality of fibre Bragg gratings in an optical fibre, each fibre Bragg grating being sensitive to a different wavelength of light, the system comprising:

a broadband source for illuminating the optical fibre;
a single optical interferometer;
light feeding means for feeding to an input of the interferometer light reflected from the fibre Bragg gratings, and
a processor for processing the output from the interferometer to determine the wavelength of the reflected light,
wherein:
the light feeding means comprise a wavelength division multiplexer operable to separate light received from the optical fibre into a plurality of wavelengths, each associated with one of the plurality of fibre Bragg gratings, the wavelength division multiplexer having multiple channels, one for each of the plurality of fibre Bragg gratings;
and
an optical switch is operable to selectively switch light from each of the plurality of fibre Bragg gratings into the single optical interferometer in a time separated series.

5 more elements

A method for measuring an absolute wavelength in a system having at least one fibre Bragg grating in an optical fibre, each fibre Bragg grating being sensitive to a different wavelength of light, the method comprising:

during an initializing stage of said system:
illuminating the optical fibre with a broadband source;
inputting light reflected from the at least one fibre Bragg grating to a single optical interferometer that has two input arms;
varying the optical path difference between the interferometer arms;
and
determining the absolute wavelength using any change of phase caused by the change of optical path difference;
and
storing the absolute wavelength as a function of change in phase;
and
during use of said system, using the stored absolute wavelength reference value and a measure of change of phase to determine absolute wavelength of light reflected from the at least one fibre Bragg grating.

7 more elements

Dependencies are inferred from the claim text.

Optical fibre sensor interrogation system

Life of this patent

Optical fibre sensor interrogation system

Life of this patent

Abstract

Claims12