DFOSS

Distributed Fiber Optic Sensing Technology

The distributed fiber optic sensing technology (DFOS) measures the strain and temperature change based on the changes in the backscattering of light in fiber optic sensors. The DFOS technology based on the Brillouin scattering, measures the frequency shift spectrum at any location along a fiber optic cable, where the laser light is launched into.

At present, this Brillouin scattering technology can be categorized into two main types, the Brillouin Optical Time Domain Analysis (BOTDA) and the Brillouin Optical Time Domain Reflectometry (BOTDR).

In BODTA, the optical stimulation leads to a greater intensity of the scattering mechanism and hence an improved signal to noise ratio coincides.

Measurement using BOTDA requires access of the two ends of a fiber optic cables. For BOTDR, the detection of a relatively lower intensity scattered light required longer time and long pulse which will affect the spatial resolution.

However, BOTDR has an advantage that it is able to access to only one fiber end, i.e. possible to take measurement if fiber if broken at certain location.

DFOS is offering new possibilities in geotechnical and structural health monitoring. Installing a single DFOS cable in soil or structure allows the acquisition of a great amount of accurate relative strain measurements.