Here are answers to questions we are most frequently asked. You may find your question answered here. If not, please contact us we are here to help, and it may save you precious time.
Contact us
Why consider distributed sensing when conventional sensors (e.g., strain gauges, extensometers, Pt100 temperature sensors) do a good job?
Conventional sensors:
Distributed sensing relies on optical fiber sensing cables:
Distributed fiber optic sensing is the only cost-effective way to monitor kilometers of concrete, steel, soil, or rock for early signs of failure. As a sensing technique, it is a powerful and highly efficient tool.
It detects and locates deformation, cracking, ground movement, and temperature events that could infer erosion, seepage or a leak. Optical fibers are truly distributed sensors, detecting and locating early signs of deformation inferred from changes in strain or temperature (or both). Electrical fields do not affect fiber optics, which withstand lightning, chemically aggressive environments, and long-term aging effects.
Distributed fiber optic sensing is cost-effective for larger or longer projects. As a rough guide, monitoring 100’000 points over 50 km works out usually at less than 10 Euros per point (including instrument and fiber optic sensing cable. Engineering cost, installation, and sundries not included). That’s economically advantageous for continuous automatic sensing, especially since the sensing cable needs no maintenance.
| Technology | Sensing | Physical Effect | Main Applications | Capabilities |
|---|---|---|---|---|
| Distributed Strain and Temperature Sensing Brillouin DTSS | Strain and temperature | Brillouin scattering |
Structural health Geohazard detection Deformation monitoring Power cable condition | Long-term stable measurements of both strain and temperature No re-calibration required |
| Distributed Temperature Sensing Raman DTS | Temperature | Raman scattering |
Fire detection Power cable condition monitoring Leakage detection |
Ideal for temperature only measurement |
| Distributed Acoustic Sensing Rayleigh DAS | Vibration/Acoustics | Rayleigh scattering |
Seismic profiling Intrusion detection Leakage detection |
Dynamic distributed acoustic data |
There are systems to meet most requirements for continuous monitoring of large, long, or complex structures. Since each project is different, we can help you specify a configuration to fulfill the project’s requirements. And if fiber optic sensing is not ideal for your project, we’ll tell you that too.
Here are a few questions for you that help define the configuration:
Yes. Our Brillouin technology-based instruments (BOFDA, BOFDR) monitor strain and temperature or temperature compensation for strain. The sensing cable contains fiber in a loose tube to measure temperature. While for strain, a tight-buffered fiber is required. Contact us for help defining which fiber optic sensor (sensing cable) is the right one for your project.
Distance is no problem for fiber optic sensing. fibrisTerre’s system monitors from a few tens of meters to 80 km from a single interrogator. A geogrid or geosynthetic may be used as a carrier. A multi-channel switch allows multiple sensing cables to be interrogated, enabling monitoring of larger areas or cross-sections of complex structures.
Talk to us. As necessary, we will put you in touch with an integrator, specialist installer, or agents near you to make sure you benefit from local and application-specific service and support.
The sensing cable is very similar to a fiber optic telecoms cable. The fiber inside is single-mode. For strain monitoring, the fiber will be held tightly in the cable (tight-buffered) so that the cable detects the strain in the structure. For temperature measurement, the fiber is contained in a loose tube within the cable. Sensing cables are available with various ruggedized structures and materials to ensure fitness-for-purpose and longevity in different applications.
A broken fiber can be repaired or replaced. Redundancy is built into a good monitoring design. There are guidelines for handling the fiber optic cable, which is why we rely on specialist installers and agents to specify and install the sensor correctly. Our in-house specialists help with both equipment and sensing cable selection and configuration.
An application-specific sensing cable will give the best results. Sometimes, temperature monitoring can use an existing fiber optic cable. Monitoring strain usually requires a tight-buffered fiber which is unlikely to be found in an existing telecoms cable.
fibrisTerre’s fTB instrument series provides a range of interface options for data handling and instrument control. These enable seamless integration into SCADA systems, third-party data visualization software, FE modeling, GIS representation, and digital twins.
fibrisTerre’s fTB 5020 interrogator range is designed for reliability. The unit weighs only 7 kg, consumes a mere 40 W, and is sealed against dust ingress. It operates at temperatures between 0 and 45°C.
Your fibrisTerre instrument and its computer arrive in a ruggedized trolley as standard. This is ideal for surveys and interventions. You will need a power supply. For continuous monitoring, the instrument requires housing in a controlled environment. A rack-mounted option is available, with UPS, suitable for substations.
Designed for long-term, continuous monitoring, the system divides into two parts:
Fiber optic cables are robust and passive and are deployed in industrial projects demanding a life expectancy of one hundred years. For the instruments, optical switches, computers, and other electronic components, fibrisTerre offers servicing and warranty plans to ensure that your measurements are continuous.
