Frequency-scanned optical time domain reflectometry
AssigneeSchlumberger Technology Corporation
InventorArthur H. Hartog
Life of this patent
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Abstract
A frequency-scanned optical time domain reflectometry technique includes launching a plurality of interrogating pulses into an optical fiber at a plurality of optical carrier frequencies. A Rayleigh backscatter signal is detected for each interrogating pulse as a function of time between the launching of the pulse and the detection of the backscatter signal. The time resolved Rayleigh backscatter signal at each optical frequency may then be examined to determine a distribution of a physical parameter along the length of the optical fiber.
Claims30
A method of determining a physical parameter associated with an optical fiber, comprising:
- launching a plurality of interrogating pulses into the optical fiber, wherein at least a first interrogating pulse has a first optical frequency and a second interrogating pulse has a second optical frequency different than the first optical frequency;
- acquiring, for each of the plurality of interrogating pulses, time resolved Rayleigh backscatter signals at a plurality of locations along at least a portion of the length of the optical fiber;
- comparing the time resolved Rayleigh backscatter signals from the first plurality of interrogating pulses with the time resolved Rayleigh backscatter signals from the second plurality of interrogating pulses;
- and
- based on the comparing, determining a distribution of a first physical parameter along at least the portion of the length of the optical fiber.
A system, comprising:
- an optical fiber;
- an optical source to output an optical pulse at each of a plurality of optical frequencies for launching into the optical fiber;
- and
- a detection and acquisition system coupled to the optical fiber and configured to:
- detect Rayleigh backscatter corresponding to each launched optical pulse as a function of time;
- based on the detected Rayleigh backscatter, acquire a time resolved coherent Rayleigh spectra (TRCRS) measurement corresponding to each of the optical frequencies;
- save at least one of the time resolved coherent Rayleigh spectra (TRCRS) measurements as a baseline;
- compare the time resolved Rayleigh coherent spectra (TRCRS) corresponding to given optical frequencies to the baseline;
- and
- determine a distribution of a physical parameter along a length of the fiber based on the TRCRS measurement comparison at each of the plurality of optical frequencies.
A method of determining a physical parameter associated with an optical fiber, comprising:
- providing a signature of the optical fiber, the signature corresponding to time resolved coherent Rayleigh spectra measurements taken along at least a portion of the optical fiber at a plurality of optical frequencies;
- launching a plurality of interrogating pulses into the optical fiber, wherein at least a first interrogating pulse has a first optical frequency and a second interrogating pulse has a second optical frequency different than the first optical frequency;
- acquiring, for each of the plurality of interrogating pulses, time resolved Rayleigh backscatter spectra at a plurality of locations along at least a portion of the length of the optical fiber;
- comparing the acquired time resolved Rayleigh backscatter spectra to the signature;
- and
- based on the comparing, determining a distribution of a physical parameter along at least the portion of the length of the optical fiber.
Dependencies are inferred from the claim text.