Distributed Fibre Optic Sensing for Event Detection

Abstract

A fibre optic sensing method and apparatus for determining location and direction information of disturbances occurring in the environment of a sensor optical fibre are provided. The method comprises launching optical pulses into at least one polarisation eigenmode of a polarisation maintaining fibre as the sensor optical fibre, detecting temporal speckle patterns of light backscattered from the at least one polarisation eigenmode of the fibre, comparing the temporal speckle patterns to determine the location and direction information of a disturbance in the environment of the sensor optical fibre. The location information may be a distance along the fibre, and the direction information may be a direction radially from the axis of the fibre. The apparatus or instrument may be used to detect disturbance over long distances such as pipes, pipelines, or wells. Other applications include detecting intruders entering a controlled area.

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