The Distributed Acoustic Sensor (DAS) measures the true acoustic field every 1m over up to 50km of sensing fibre. It does this by sending an optical signal into the fibre and looking at the naturally occurring reflections that are scattered back all along the glass. By analyzing these reflections, and measuring the time between the laser pulse being launched and the signal being received, the DAS can measure the acoustic signal at all points along the fibre.

The DAS measures from one end of a standard single mode telecoms fibre. It can be used with existing cables.

The Distributed Temperature Sensor (DTS) illuminates the sensing fibre with a series of sub-nanosecond duration pulses. As the pulses propagate down the fibre, a small amount of light is backscattered towards the laser source. The majority of the backscatter, Rayleigh light, is at the same optical wavelength, as the laser and is not temperature sensitive. However, a small proportion of the light is scattered by the Raman process and is temperature dependent. By recording the backscattered Raman light as a function of time, the temperature at all points along the fibre can be determined.

Applications:

• Distributed Flow profiling;
• Distributed Seismic analysis;
• Fracturing;
• Assessment  of Hydrological Dynamics;
• Active and Passive Seepage Detection in Dams and Dikes;
• Monitoring of Geothermal Wells;
• Power Cable Monitoring;
• Monitoring of Gas Storage Reservoirs;
• Long distance pipeline monitoring;
• Border surveillance;
• Perimeter monitoring;
• Tunneling activity detection;
• Transport & critical infrastructure security;
• Port, harbor & coastal waters surveillance;
•  Railways monitoring.