By TEBAOFLEX Jyen. Originally published on January 14, 2026.
Distributed fiber sensing uses the optical fiber as part of a measurement system, but the cable decides how the environment reaches that fiber. Distributed acoustic sensing (DAS), temperature sensing (DTS) and strain sensing (DSS) therefore require different combinations of coupling, protection and calibration. A robust telecom cable is not automatically an accurate structural sensor.
Start with the measurement objective
- DAS: measure dynamic disturbances through a defined interrogator response, gauge length and mechanical coupling.
- DTS: measure temperature along the route, with a suitable response time and a method for controlling unwanted influences.
- DSS: transfer relevant deformation from the host material into the sensing fiber, with a known relationship between measured fiber strain and structural strain.
Raman, Brillouin and Rayleigh methods are not interchangeable labels for the same instrument. Confirm the supported fiber type, optical configuration, range, resolution, sampling and calibration with the interrogator manufacturer. Cable protection must not isolate the measurand that the system is intended to detect.
Coupling and temperature compensation
A strain-relieved fiber can reduce mechanical cross-sensitivity in a temperature application. A bonded or otherwise mechanically coupled fiber can measure deformation, but the full chain—from concrete, grout or soil through jacket and internal layers—determines strain transfer. Creep, slip and installation details can change the result.
A simplified Brillouin relation is delta_f = CT × delta_T + Ce × delta_epsilon. The coefficients need calibration for the fiber and system. For illustration only, if CT = 1.08 MHz/°C and Ce = 0.048 MHz/microstrain, 200 microstrain produces 9.6 MHz, equivalent to 8.89°C if wrongly interpreted as temperature alone.
A nearby temperature-reference fiber can support compensation only when its thermal response, location and calibration are appropriate. Simply subtracting two uncalibrated traces does not guarantee pure structural strain or a fixed microstrain accuracy.
Do not infer construction from a product-family name
Solifos’ published BRUsens range provides examples of temperature, strain and hybrid sensing constructions. Its BSSH V13 is described as a configurable hybrid containing three stranded fiber-in-metal tubes and a structured sheath. That contradicts a blanket description of the model as having no tubes. BRUsens is referenced as the manufacturer’s product family, not as evidence of TEBAOFLEX qualification.
A metal tube may provide useful mechanical and environmental protection, but its alloy name alone does not prove perfect hermeticity or eliminate optical ageing. Similarly, bulk metal thermal conductivity cannot establish the response time of an installed cable surrounded by grout, soil or insulation.
Plan the installation and calibration together
- Define what quantity is measured and how it will inform an alarm or engineering decision.
- Choose cable-to-structure coupling, attachment spacing, grout or burial method and any pre-strain.
- Record optical route length versus physical chainage, splices and inaccessible sections.
- Establish temperature compensation and reference sensors where needed.
- Verify response with a controlled commissioning stimulus and record a baseline.
For DAS, cable orientation and mechanical coupling influence sensitivity. Published field research on DAS calibration emphasizes that recorded fiber strain is not automatically equal to host-rock strain. There is no universal sound-gain improvement or detection distance from adding one armour layer.
Acceptance evidence
Request construction and optical data, relevant mechanical and environmental qualification, and a system-specific calibration/commissioning plan. State test wavelengths, load conditions, spatial resolution and acceptance criteria. OTDR continuity alone does not demonstrate accurate temperature, strain or acoustic measurement, and no unprovided proprietary laboratory results are claimed here.
Sources and application documentation
Discuss the application
Send the application duty, installation drawing and required acceptance criteria to TEBAOFLEX. WhatsApp: +86 185 9591 3361. Request the applicable product documentation before ordering.