Distributed Optical Fibre Sensor
AssigneeFotech Solutions Limited
InventorAlan John Rogers
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Abstract
A distributed optical fibre sensor is described. The sensor uses a sensor fibre (10) having a low or zero intrinsic birefringence that is responsive to an environmental parameter (24) such as pressure. Probe light pulses having a diversity of launch polarisation states are used to reduce signal fading and polarisation dependent loss in the retardation beat frequency signals which are sensed (20) and then analysed (22) to determine the environmental parameter as a profile along the sensor fibre.
Claims33
A distributed optical fibre sensor comprising:
- a monomode sensor fibre for disposing in an environment such that the birefringence of the sensor fibre is responsive to at least one environmental influence;
- a light source arranged to launch pulses of probe light each having a defined launch polarisation state into the sensor fibre;
- a detector arranged to receive probe light following backscatter of said pulses within the sensor fibre, and to detect retardation beat frequency signals from the received probe light using one or more detector polarisation states;
- and
- an analyser arranged to determine at least one parameter indicative of said environmental influence, as a profile along at least part of the sensor fibre, from properties of the retardation beat frequency signals.
A method of mapping an environmental parameter along a sensor optical fibre, comprising:
- launching a series of probe light pulses into the sensor optical fibre;
- detecting a retardation beat frequency signal in probe light backscattered from the sensor optical fibre;
- and
- mapping the parameter as a profile along the sensor fibre from the retardation beat frequency signals of the plurality of pulses.
Dependencies are inferred from the claim text.