US 7,564,540 B2 · Fibre optic sensor method and apparatus

Abstract

This invention uses an interferometric fiber optic sensor, particularly a Sagnac or Michelson interferometer, in a first fiber to monitor a sensing length of the first fiber and to detect disturbances. Signals indicating disturbances are classified as being of interest or not of interest, depending on predetermined criteria. Disturbances of interest can be, for example, the breaking of reinforcement wires in concrete pipe, the breaking of wires in suspension cables, a fire, a pipeline leak, or an intrusion. A location sensor system is used to determine the location of disturbances of interest, and to confirm the interferometer signal to reduce noise. The location sensor system is a fiber optic sensor, such as a phase OTDR sensor or a Brillouin effect sensor, which can detect the location of events it senses. It is present either in the first fiber or in a separate fiber laid adjacent the first fiber along its sensing length, as for example in the same optical cable.

Claims20

Dependent claims

A fibre optic monitoring system for detecting and locating disturbances along a predetermined length, which comprises:

a first fibre optic sensor which extends along said predetermined length and which continuously detects disturbances along the entire predetermined length and produces a first output
a second fibre optic sensor which extends along said predetermined length and which produces a second output which detects disturbances and their locations along the predetermined length
means for analyzing the output of said first fibre optic sensor to identify disturbances sensed by said first fibre optic sensor which have at least one predetermined characteristic
means for analyzing the output of said second fibre optic sensor to determine whether a disturbance was sensed by said second fibre optic sensor at a time approximately corresponding to the time at which the first fibre optic sensor sensed a disturbance with said one predetermined characteristic, and, if so, the location, along said predetermined length, of the disturbance sensed by the second fibre optic sensor.

1 more element

Dependencies are inferred from the claim text.

Fibre optic sensor method and apparatus

Life of this patent

Fibre optic sensor method and apparatus

Life of this patent

Abstract

Claims20