DISTRIBUTED TEMPERATURE AND STRAIN SENSING (DTS/DSS): PRINCIPLES AND INDUSTRIAL APPLICATIONS
WHY TEMPERATURE AND STRAIN MONITORING HAS BECOME A STRATEGIC CHALLENGE
Mechanical strain is one of the most fundamental indicators of the health and behavior of physical assets. Whether in pipelines, telecom and power cables, bridges, tunnels, dams, wells, or large civil structures, strain reveals how materials deform under ground movement, temperature and load changes, or internal pressure.
Temperature is also a key insight to monitor as it can reveal a leak that could compromise the asset’s integrity.
Excessive or unexpected temperature and/or strain often precedes structural damage, fatigue, leaks, failures, or safety incidents. Yet, monitoring both parameters accurately over long distances and extended assets remains a major challenge.
Traditional temperature and strain measurement techniques are limited by:
- Point-based measurements,
- Complex installation and cabling,
- Vulnerability in harsh environments,
- Limited scalability for long or buried assets
As infrastructure networks expand and age, operators increasingly need continuous, distributed temperature and/or strain visibility, not just isolated measurements.
This is where Distributed Temperature and Strain Sensing (DTS/DSS), also referred to as DTSS or DSTS, has become a key enabling technology.
By using optical fiber as a continuous sensor, DTS/DSS provides real-time or quasi–real-time temperature and strain profiles over tens of kilometers, offering unmatched insight into the mechanical behavior of critical assets and its integrity. Originally developed for geotechnical and energy applications, DTS/DSS is now widely used across infrastructure monitoring, energy, oil & gas, geotechnical engineering, and Structural Health Monitoring (SHM).
This page explains what Distributed Temperature and Strain Sensing is, how it works, and why it is becoming a cornerstone of modern asset integrity strategies.
WHAT IS DISTRIBUTED TEMPERATURE AND STRAIN SENSING (DTS/DSS)?
Distributed Temperature and Strain Sensing (DTS/DSS) is a fiber optic sensing technology that uses an optical fiber as a continuous, distributed temperature and strain sensor.
Instead of measuring at discrete locations, DTS/DSS provides temperature and/or strain measurements at every point along the fiber, typically with:
- Minimum spatial resolution of 1 meter
- Sensing ranges up to 100 km
- High measurement stability over long periods
In practical terms, a single optical fiber can replace thousands of conventional temperature and strain sensors, delivering a complete profile of a structure or asset.
The fiber itself acts as the sensing element, while a dedicated optoelectronic unit, called a DTS/DSS interrogator, analyzes backscattered light to calculate both strain and temperature, enabling accurate monitoring even in thermally varying environments.
THE PHYSICAL PRINCIPLE BEHIND DTS/DSS: BRILLOUIN SCATTERING
LIGHT PROPAGATION AND SCATTERING IN OPTICAL FIBER
When a laser pulse propagates through an optical fiber, a small portion of the light is scattered backward due to interactions between light and the acoustic waves naturally present in the fiber material. This phenomenon is known as Brillouin scattering.
Unlike Rayleigh scattering (used for DAS) or Raman scattering (used for DTS), Brillouin scattering is sensitive to both strain and temperature.
BRILLOUIN FREQUENCY SHIFT
The key parameters measured in DTS/DSS is the Brillouin Frequency Shift (BFS) and its amplitude variation. These fluctuations vary linearly with:
- Mechanical strain applied to the fiber
- Temperature of the fiber
By precisely measuring the BFS and the amplitude as functions of distance - determined from the time-of-flight of the backscattered light - the interrogator can reconstruct distributed strain and temperature profiles along the fiber.
SEPARATING STRAIN AND TEMPERATURE
Because Brillouin scattering is sensitive to both parameters, DTS/DSS systems rely on:
- Temperature compensation using reference fibers
- Combined DTS/DSS architectures
- Or advanced signal processing techniques
to isolate true mechanical strain from thermal effects.
This capability makes Brillouin based sensing ideal for long-term structural and geotechnical monitoring.
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HOW A DISTRIBUTED TEMPERATURE AND STRAIN SENSING SYSTEM WORKS
A DTS/DSS system is built around three main components.
THE OPTICAL FIBER
The sensing element is a standard or specially coated optical fiber, which can be:
- Bonded to structures (bridges, tunnels, buildings)
- Embedded in concrete or composite materials
- Installed along pipelines or telecom and power cables
- Buried in soil or rock for geotechnical monitoring
- Deployed in wells or boreholes
The way the fiber is installed is critical: while temperature monitoring can be performed with a loose fiber, accurate strain monitoring requires good mechanical coupling between the fiber and the structure to ensure accurate strain transfer.
THE DTS/DSS INTERROGATOR
The interrogator is the core measurement unit. It:
- Injects laser pulses into the fiber
- Analyzes Brillouin backscattered signals
- Measures the local Brillouin frequency shift and amplitude variation
- Calculates distributed strain and temperature
Modern industrial interrogators, such as the FEBUS G1-R or FEBUS G1-C (portable), are designed to deliver:
- High strain resolution (typically a few microstrain)
- Long sensing range
- Excellent repeatability
- Robustness for field deployment
Whether the FEBUS G1-R provides long-term continuous monitoring applications, including:
- Structure integrity
- Pipeline integrity
- Installed cables
The FEBUS G1-C is intended for periodic or short-term monitoring campaigns, such as:
- Intermittent monitoring during bridge and dam construction
- Field geotechnic trials
- Monitoring of cable integrity during offshore deployments
The FEBUS G2 further enhances monitoring capabilities by directly discriminating strain and temperature effects in real time during the measurement process, providing more accurate and reliable data interpretation.
DATA PROCESSING AND SOFTWARE
Raw DTS/DSS data consists of distributed temperature and strain profiles evolving over time.
Advanced software platforms enable operators to:
- Visualize temperature and/or strain profiles and trends
- Define alarm thresholds and zones
- Detect abnormal deformation patterns
- Correlate strain with temperature, load, or events
- Integrate data into SHM, SCADA, or asset management systems
This software layer turns DTS/DSS into a powerful decision support tool.
KEY CHARACTERISTICS OF DISTRIBUTED TEMPERATURE AND STRAIN SENSING
CONTINUOUS, DISTRIBUTED MEASUREMENTS
DTS/DSS provides true distributed temperature and strain sensing, not interpolation between sensors. Every meter of fiber is an independent measurement point.
LONG-DISTANCE COVERAGE
A single interrogator can monitor tens of kilometers of fiber, making DTS/DSS ideal for extended and linear assets.
HIGH SENSITIVITY AND STABILITY
DTS/DSS can detect very small strain and/or temperature variations and is well suited for long-term monitoring with minimal drift.
PASSIVE AND INTRINSICALLY SAFE TECHNOLOGY
The fiber contains no electrical components, no power supply, and no active electronics in the field, making DTS/DSS ideal for:
- Hazardous environments
- Remote locations
- Underground or underwater assets
WHAT CAN DISTRIBUTED TEMPERATURE AND STRAIN SENSING DETECT?
Distributed Temperature and Strain Sensing can reveal a wide range of phenomena, including:
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Because damages often appears before visible failures, DTS/DSS enables early detection of structural issues.
TYPICAL APPLICATIONS FOR DTS/DSS
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STRUCTURAL HEALTH MONITORING (SHM) |
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DTS/DSS is increasingly used for continuous Structural Health Monitoring of:
By tracking temperature and strain evolution over time, operators can:
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PIPELINE INTEGRITY AND GROUND MOVEMENT MONITORING |
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For pipelines crossing unstable terrain, DTS/DSS enables:
Combined solutions such as FOPipe leverage distributed temperature and strain data to enhance pipeline integrity management by providing early alerting, classification, and precise map localization of events. |
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UNDERGROUND INFRASTRUCTURE, TELECOM AND POWER CABLE MONITORING |
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For the telecommunications and energy sectors, DTS/DSS helps monitor:
Integrated platforms like FOGrid combine strain and temperature data to provide a comprehensive view of cable health, enabling operators to optimize production and lower maintenance costs. |
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GEOTECHNICAL AND NATURAL HAZARD MONITORING |
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DTS/DSS is widely used in geotechnical engineering to monitor:
The dense spatial sampling offered by DTS/DSS provides valuable insight into soil and rock deformation patterns. |
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WELL AND RESERVOIR MONITORING |
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In oil, gas, geothermal, and CO₂ storage wells, DTS/DSS supports:
When combined with DAS, DTS/DSS contributes to comprehensive well monitoring solutions such as FOWell. |
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KEY TECHNICAL PARAMETERS TO CONSIDER
DEPLOYMENT BEST PRACTICES AND CHALLENGES
When evaluating a DTS/DSS system, important parameters include:
- Spatial resolution: distance between strain measurement points
- Sensing range: maximum fiber length
- Acquisition time: update rate of strain profiles
Selecting the optimal configuration requires expertise in fiber optics, installation methods, and application-specific constraints.
Successful DTS/DSS projects depend on:
- Proper fiber selection and installation technique
- Suitable mechanical coupling to the monitored structure
- Careful temperature compensation
- Robust data processing and interpretation
- Integration into operational workflows
End-to-end FEBUS Optics solutions combining hardware, software, and application expertise are critical to achieving reliable and actionable results.
DISTRIBUTED TEMPERATURE AND STRAIN SENSING WITHIN DFOS TECHNOLOGIES
DTS/DSS is part of the broader family of Distributed Fiber Optic Sensing (DFOS) technologies, which also includes:
- Distributed Acoustic Sensing (DAS) based on Rayleigh scattering
- Distributed Temperature Sensing (DTS) based on Raman scattering
Together, DAS, DTS (Raman-based), and DTS/DSS provide complementary insights into vibration, temperature, and mechanical deformation, enabling holistic asset monitoring.
WHY DISTRIBUTED TEMPERATURE AND STRAIN SENSING IS STRATEGIC
Several trends are driving DTS/DSS adoption:
- Aging infrastructures
- Increased focus on resilience and safety
- Growing geotechnical risks
- Stricter regulatory requirements
- Demand for data-driven asset management
DTS/DSS supports these needs by delivering continuous, reliable, and spatially dense temperature and strain information.
FROM DISTRIBUTED TEMPERATURE AND STRAIN DATA TO STRUCTURAL INSIGHT
Distributed Temperature and Strain Sensing transforms an optical fiber into a powerful, continuous temperature and strain sensor capable of monitoring the mechanical behavior of critical assets and its thermal profile over long distances.
By leveraging Brillouin-based photonics, advanced signal processing, and industrial-grade software, DTS/DSS enables operators to detect abnormal behaviors early, and make informed decisions.
For organizations managing complex infrastructures, DTS/DSS is not just a sensing technology, it is a strategic tool for safer, more resilient, and more efficient operations.