Fibre Optic Distributed Sensing
First Claim
1. A method of distributed fibre optic sensing comprising performing a series of interrogations of an optical fibre, each interrogation comprising launching interrogating radiation comprising at least one pulse pair into the fibre, wherein the pulses of a pulse pair are introduced to the optical fibre with a time interval therebetween, and sampling radiation which is Rayleigh backscattered from within said fibre to obtain at least one sample from each interrogation;
- and determining any phase modulation in the samples, wherein the step of determining the phase modulation comprises isolating components of the phase modulation which are below a threshold frequency.
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Abstract
A method of distributed fibre optic sensing is described. In an example, a series of interrogations are launched into an optical fibre, each interrogation comprising interrogating radiation in at least one pulse pair, wherein the pulses of a pulse pair are introduced to the optical fibre with a time interval therebetween. Radiation backscattered therefrom is sampled, so as to obtain at least one sample from each interrogation. Phase modulation in the samples is determined and components of the phase modulation which are below a threshold frequency are isolated. Such a method of sensing could be used, for example, to monitor changes in temperature of the optical fibre.
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Citations
24 Claims
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1. A method of distributed fibre optic sensing comprising performing a series of interrogations of an optical fibre, each interrogation comprising launching interrogating radiation comprising at least one pulse pair into the fibre, wherein the pulses of a pulse pair are introduced to the optical fibre with a time interval therebetween, and sampling radiation which is Rayleigh backscattered from within said fibre to obtain at least one sample from each interrogation;
- and determining any phase modulation in the samples, wherein the step of determining the phase modulation comprises isolating components of the phase modulation which are below a threshold frequency.
- View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
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17. A distributed fibre optic sensor apparatus comprising:
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an optical source configured to, in use, launch a series of interrogations, each interrogation comprising a pulse pair, into an optical fibre, wherein the pulses of a pulse pair are introduced to the optical fibre with a time interval therebetween; a sampling detector configured to, in use, sample radiation which is Rayleigh backscattered from within said optical fibre from the interrogations; and a processor configured to determine any phase modulation in the samples, and to isolate components of the phase modulation below a threshold frequency. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
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Specification