Optical time-domain reflectometry
AssigneeYork Limited
InventorsArthur H. Hartog, Martin P. Gold, Adrian P. Leach
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Abstract
An optical time-domain reflectometry method of sensing respective values of a physical parameter, such as temperature, at different locations along an optical fibre, in which back-scattered optical radiation is used to produce output signals indicative of the values being sensed, is improved by employing optical filtering means to ensure that the back-scattered radiation used is restricted to a preselected single spectral line resulting from inelastic scattering in the fibre, for example one of the Anti-Stokes Raman lines, or to two mutually adjacent such lines.
Claims20
An optical time-domain reflectometry method of sensing respective values of a physical parameter at different locations along an optical fibre, in which method radiation is launched into the fibre at one end thereof and resulting back-scattered optical radiation is used to produce electrical output signals indicative of the values being sensed, wherein optical filtering means are employed to ensure that said back-scattered radiation used to produce the electrical output signals is restricted to a preselected single spectral line resulting from inelastic scattering in the fibre.
An optical time-domain reflectometry method of sensing respective values of a physical parameter at different locations along an optical fibre, in which method radiation is launched into the fibre at one end thereof and resulting back-scattered optical radiation is used to produce electrical output signals indicative of the values being sensed, wherein optical filtering means are employed to ensure that said back-scattered radiation used to produce the electrical output signals is restricted to two preselected spectral lines that are closely adjacent to one another and result from inelastic scattering in the fibre, the back-scattered radiation of these lines being directed from the filtering means onto a common optical detector, so as to be additive in effect thereon.
Optical time-domain reflectometry apparatus, for sensing respective values of a physical parameter at different locations throughout a region of interest, said apparatus comprising:
- an optical fibre, for deployment through said region of interest;
- source means for launching radiation into said optical fibre at one end thereof, to be back-scattered therein at different locations therealong;
- sensor means for receiving, from said one end of the optical fibre, such back-scattered radiation and producing electrical signals in response thereto;
- electronic processing circuitry, having an input connected to said sensor means, for employing said electrical signals to produce electrical output signals indicative of said respective values;
- and
- optical filtering means, arranged between said sensor means and said one end of the optical fibre, for ensuring that said back-scattered radiation received by said sensor means is restricted to a preselected single spectral line resulting from inelastic scattering in the fibre.
Optical time-domain reflectometry apparatus, for sensing respective values of a physical parameter at different locations throughout a region of interest, said apparatus comprising:
- an optical fibre, for deployment through said region of interest;
- source means for launching radiation into said optical fibre at one end thereof, to be back-scattered therein at different locations therealong;
- a sensor for receiving, from said one end of the optical fibre, such back-scattered radiation and producing electrical signals in response thereto;
- electronic processing circuitry, having an input connected to said sensor, for employing said electrical signals to produce electrical output signals indicative of said respective values;
- and
- optical filtering and directing means, arranged between said sensor and said one end of the optical fibre, for ensuring that said back-scattered radiation received by said sensor is restricted to two preselected spectral lines that are closely adjacent to one another and result from inelastic scattering in the fibre, and for directing the radiation of those lines onto said sensor so as to be additive in effect thereon.
Dependencies are inferred from the claim text.