Application of Distributed Fiber Optic Sensings

Distributed fiber optic sensing is a sensor that uses a unique distributed fiber optic detection technology to measure or monitor spatial distribution and temporal change information along the fiber optic transmission path. It arranges sensing fiber along the field and can simultaneously obtain spatial distribution and temporal change information of the measured field, which has many attractions for many industrial applications.

The working principle of the distributed fiber optic sensing system is to simultaneously use fiber optic as the sensing sensitive element and transmission signal medium, and use advanced OTDR technology and OFDR technology to detect temperature and strain changes at different positions along the fiber optic, realizing truly distributed measurement. The temperature measurement principle is based on the scattering effect of the distributed temperature sensing system; the strain measurement principle is based on the scattering effect of the distributed temperature and strain sensing system, which can measure temperature and strain simultaneously.

Features of distributed fiber optic sensing

• The sensing element in the distributed fiber optic sensing system is only the fiber optic.

• A one-time measurement can obtain a one-dimensional distribution map of the measured area in the entire fiber optic area. If the fiber optic is laid out in a grid shape, the two-dimensional and three-dimensional distribution of the measured area can be determined.
  

• The spatial resolution of OTDR system is generally in the meter level, while the spatial resolution of OFDR technology can reach the millimeter level.
  

• The measurement accuracy of the distributed fiber optic sensing system generally exists in a mutually restrictive relationship with spatial resolution.
  

• The detection signal is generally weak, so the signal processing system requires a high signal-to-noise ratio.
  

• Since a lot of signal addition and averaging, frequency scanning, and phase tracking are required during the detection process, a long time is needed to complete a complete measurement.
  

Applications of Distributed fiber optic sensings

Structural monitoring: 

Stress-strain and temperature monitoring of large structures such as pipelines, offshore oil platforms, oil wells, dams, levees, bridges, buildings, tunnels, and cables.

Leakage detection: 

Liquid or natural gas pipelines, industrial processing, dams, tanks.

Transportation: 

Detection of road icing, railway monitoring.

Security systems:

Fire or overheating temperature detection, power cable monitoring, signal eavesdropping monitoring, monitoring of garbage treatment stations, monitoring of landslides.

Fiber optic communication:

Online control of fiber optic cable production, fiber optic cable maintenance, working fiber optic cable strain monitoring, fiber doping measurement.

Environmental measurement:

Long-term temperature measurement of heat, ventilation, and air conditions, external marine, forest, and field locations.