Distributed Acoustic Sensor: Mapping Strain and Vibration with Optical Fibre Seminar

Distributed optical fibre sensors (DOFS) have some unique features that has no parallel in conventional sensing techniques. The ability of measuring physical phenomenon such as temperatures and vibrations at thousands of points along a single fibre under harsh conditions and in an inaccessible environments is particularly interesting for the monitoring of structures such as pipelines, flow lines, oil wells, and boreholes. Despite a steady improvement in the performance of DOFS, most of the research has been focused on advancing DC and quasi-DC distributed sensors. Recently, we have developed a distributed vibration sensor, also known as distributed acoustic sensor (DAS), capable of fully quantifying dynamic disturbances along the optical fibre. Using a technique known as optical time-domain reflectometry (OTDR), the sensor has been used to measure the frequency components of multiple disturbances along a 4km sensing fibre simultaneously. In this presentation, distributed optical fibre sensors will be defined and their advantages over conventional sensing techniques will be discussed. The principle of operation of optical time domain reflectometry (OTDR) sensing technique will be explained. Finally, the principle of DAS will be discussed.