Tag: distributed sensing

Structural Health Monitoring Systems Applications

Structural health monitoring systems have found a number of applications in various fields. A complex approach including several techniques is the best solution for detecting damage and structural changes.

Here are some examples of its implementation in structures where fiber optic technology is more commonly used. Structural Health Monitoring Systems Applications

Structural Health Monitoring Common Information

The most effective methods of maintenance programs include early detection of material degradation and failure. Mostly, fiber optic systems have two purposes of applications:

Structural efficiency control during the construction;
Continuous monitoring of structural efficiency under service loads.

Structural health monitoring systems consist of three subsystems:

A network of fiber Bragg grating sensors;
An FBG interrogator that records the optical reflection from each fiber optic sensor. They are placed in the necessary locations, depending on the applications and type of the structure.
A processing unit that collects all the data from the FBG interrogator, processes it and transmits it to the user.

Distributed Sensing Systems

Distributed temperature systems are often the choice for harsh environments where traditional sensors may not be suitable. When we talk about dams, tunnels and similar structures, there are conditions that greatly affect the operation of the structures and sensors. Ground movement, earth pressure, water and groundwater have an impact on the reliability and efficiency of any monitoring system.

Specialists can monitor all deformations and temperature changes through distributed sensing. Distributed fiber optic sensors are capable of measuring various parameters from thousands of points and transmitting them to a center that provides complex data on any changes.

Distributed temperature systems are often the choice for harsh environments where traditional sensors may not be suitable. In the case of dams, tunnels and similar structures, there are conditions that have a major impact on the operation of the facility and its sensors. Ground movement, earth pressure, water and groundwater will affect the reliability and efficiency of any monitoring system.

Structural Health Monitoring of Dams

Dam safety can have a significant impact on the surrounding environment and people. That’s why structural health monitoring of the dams is an essential part of the dam safety regime. Timely detection of defects and minimizing the effects of possible damage are the main purposes of such systems. However, specialists may face some difficulties due to the height and complex structures of the dams. Comprehensive structural health monitoring can’t be fully achieved with just a few monitoring points; it requires a complete, properly designed fiber optic system. Another problem is that some areas of the dams are inaccessible or difficult to access.

There are a number of factors that can affect dam construction. These include temperature, hydrostatic pressure, chemical reactions, etc. There are also environmental factors such as air temperature, reservoir levels, and earthquakes.

All of these circumstances can be the cause of typical dam problems such as cracking, displacement, etc. The other problem is the appearance of internal erosion, which can cause the failure of the whole mechanism in the future. This problem is hard to detect. That’s why it is important to have an effective fiber optic system in place for structural health monitoring and therefore safe operation.

Accidents in dams usually occur during the first filling or in the first few years of operation. However, there are also accidents that occur later.

Structural Health Monitoring (SHM) of Tunnels

SHM is able to provide a quick assessment of the state of health of the tunnel. It is typically used for safety improvement and optimization of maintenance and operations activities. The fiber optic monitoring system provides data on any changes in indicators that could be the cause of tunnel collapse. This makes it possible to monitor the stability of the structure and take action when it’s needed.

The construction of tunnels is based on soil conditions, the functions of the tunnels themselves, and logistical issues. Underground construction is irreplaceable, especially in cities where land resources are scarce. They are not as susceptible to the effects of natural disasters as are structures on the surface of the earth.

In the hard-to-reach or problematic areas of the tunnels, distributed monitoring systems are usually recommended. This makes it easy for staff to monitor the condition of their structures and perform necessary maintenance in a timely manner. This is especially important when it comes to fires – the biggest danger in tunnels. There are special fiber optic systems for temperature control and early warning of ignition, including fiber optic heat detectors.

Today, there are automated fiber optic solutions that provide accurate monitoring from a remote location. These fiber optic devices are often designed specifically for use in critical locations. In addition, they consider the cases that may occur, such as the use of the additional FBG sensors. If the other sensor fails, they will be able to operate.

Distributed temperature sensing is a newly introduced technique capable of complex structural health monitoring systems. Temperature and pressure control is especially important for dams and tunnels with their difficult-to-access locations and other challenges that staff usually face. SHM is the solution for these situations.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) product line such as fiber Bragg grating sensors, for example, FBG strain sensors, FBG interrogators and multiplexers, Distributed Acoustic Sensing (DAS) systems, Distributed Temperature Sensing (DTS) systems. The company creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. If you are interested in structural health monitoring systems and want to learn more, please contact us at info@optromix.com

Distributed Sensing for Seismic Monitoring Systems

We have already published a range of articles referring to different applications of fiber optic technology in various industries and fields. Geophysics has also applied distributed sensing as a powerful instrument for structural health monitoring, such in, the oil and gas industry, tunnel safety monitoring, etc.

Seismic monitoring has been no exception. Resistance to electromagnetic disturbance, cost-effectiveness and possibility of implementing into hard-to-reach regions or places that can be harmful for human health are undeniable advantages of distributed sensing systems. Distributed Sensing for Seismic Monitoring Systems

What is Distributed Sensing Technology?

Distributed sensing is a technology that provides continuous measurements in real-time. Compared to traditional sensors, placed at certain points, distributed sensing acts as a sensing element along its entire length because the whole fiber optic cable is applied.

Due to the exploitation of the entire fiber optic cable all over its length, this method is considered to be one of the most cost-effective tools that can be placed in severe conditions.

Operation Principle of the Distributed Sensing Systems

In simpler terms, DAS systems as a part of the distributed sensing technology consist of several components including fiber optic cable and an attached optoelectronic device – FBG interrogator. The interrogator sends short pulses of the pulsed laser light into fiber optic cable. Then the backscattered light moves back up the fiber to the FBG interrogation unit. Due to the time that the laser pulse takes, there can be found the relation backscatter event and a fiber distance.

The FBG interrogator is connected to a processing unit that processes and stores the received data. This unit gets the raw data and transfers it into the information that is displayed in the program.

The software provides the visualized analysis that includes the previous data as well. In case there are any differences, fiber optic system alarms specialists. For instance, the system can display the location of the fiber optic cable on the map and highlight locations where the rates have changed or exceeded acceptable limits.

What’s the Difference Between DAS and DTS Systems?

Traditionally, distributed sensing systems are divided into distributed temperature sensing and distributed acoustic sensing.

The main difference between DTS and DAS systems is the type of signals they get to provide analysis. DTS systems are sensitive to temperature changes, while DAS is sensitive to acoustic vibrations. Therefore, their operation principle is also different. Due to the fiber qualities, the performance of DTS systems is able to stay at the necessary high injected pump power level. At the same time, DAS systems don’t require such high pump power as DTS systems because of the Rayleigh scattering.

DAS Systems and Their Applications in Seismic Monitoring

If we are talking about seismic monitoring, distributed acoustic sensing is used. DAS systems measure any vibrations that can’t be detected by DTS technology.

The goal of all seismic monitoring systems is warning before any accident occurs. Their effectiveness depends on the accuracy of the obtained data, lifetime and length. That’s why there is a necessity in a continuous operating system that is capable of working in severe environments and over long distances.

DAS systems were implemented as seismic monitoring systems due to the above-mentioned advantages as well as low cost, no special maintenance, robustness, etc. Therefore, distributed acoustic systems have provided new capabilities for seismic monitoring.

Field Projects Where Sensing Systems Were Applied

If we are talking about sensing systems, in most cases fiber optic sensors were more effective in comparison with the conventional electronic ones. That provides unrivaled performance, especially in critical applications.

For example, two years ago the specialists started a range of experiments in the Arctic and the Arctic Ocean. This is the first case when DAS systems were installed in the Arctic. Scientists wanted to get the analysis of the seafloor seismic activities and other processes under Arctic sea ice with a distributed acoustic sensing system. Fiber optic cable catches the vibrations about all the changes of the ocean 24/7.

The other project with DAS systems has also allowed scientists to see them in other severe environmental conditions. Since they are installed mostly in the ground, specialists have monitored their performance in snow. The most concerning parameters for them were the snow depth and severe frosts.

Finally, in the conditions of decreasing temperatures the reduction in background noise and better signal-to-noise ratio was noticed. In fact, the lower temperatures, the better results distributed acoustic sensing has provided. Cold temperatures don’t make fiber optic performance difficult or interfere with accuracy of the received data. Moreover, fiber optic cable is able to transfer signals at snow depths of at least 0.65m.

Distributed sensing as a tool for seismic monitoring systems has proved to be effective in detection of any seismic shocks and flow changes. All in all, DAS provides capabilities for seismic monitoring of the near surface.

DAS systems distributed acoustic sensing distributed sensing distributed sensing systems DTS systems FBG interrogators fiber optic cable

Distributed Acoustic Sensing (DAS) in the oil and gas industry

DAS in the oil and gas industry According to scientists, nowadays we can see newly developed distributed sensing systems that can have many appliances including monitoring of wells’ conditions in the oil and gas industry. Mostly, distributed acoustic sensing (DAS) is applied in these spheres.

The engineers have an opportunity to make decisions on operational optimization onsite with the usage of the data provided by distributed fiber optic sensors. The fiber optic technology can help in well performance improvement as well as in keeping safety at the well site. And as a result, it optimizes production from oil and gas wells. In comparison with distributed sensing, there is no such method that could provide such quality and extent of detail about physical conditions.

Mostly, distributed acoustic sensing (DAS) is produced to record fluid and gas flow signals, listen to hydraulic fracturing-related signals, etc. Distributed sensing systems trace changes in acoustic vibrations along the entire length of a fiber optic cable in real-time. In the fiber optic cable, there are thousands of detection points at minimal spatial intervals. Compared to the usual sensing systems, distributed sensing does not rely on discrete sensors at predetermined points. Distributed sensing system uses the whole fiber optics itself as a sensing unit.

Therefore, fiber optic technology is suitable for those who want to apply environmental monitoring in sensitive geologic operations. Thanks to the length of the fiber optic cable and its working ability in severe environmental conditions for long, it is quite popular for such use. The down hole fiber optic sensor application provides for oil and gas wells, flow-back operations, geothermal wells, etc.

The ability of measurement along the complete length of the fiber optic cable can be applied for many other applications like the characterization of contaminated bedrock aquifers and monitoring of geologic carbon sequestration projects. In addition to that, distributed sensing systems can also register the conditions of the near-wellbore area of subsurface rock formations.

DAS system manufacturers always have an aim of making their fiber optic solutions better. For the DAS systems, it is the regulation of acoustic and vibratory noise sensing. The ambient noise is always in sites and should not be measured.

That is why the next scientific goal for DAS technology is the creation of a portable vibration isolation system to maximize the distributed acoustic sensing system’s dynamic range.

Optromix is a DAS system manufacturer that provides top-of-the-line distributed acoustic sensing systems suitable for monitoring commerce networks. If you have any questions or would like to buy a DAS system, please contact us at info@optromix.com

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Distributed Acoustic Sensing (DAS) and its applications

DAS and its applications In southwest Iceland, there is a fiber optic cable that connects two geothermal power plants. It is used as every casual fiber optic cable for data transmitting. However, in 2015 a research team decided to apply it for detecting seismic waves of earthquakes, so they could draw a map of the underground features including geological faults. And distributed acoustic sensing (DAS) made it possible.

Scientists made their discovery thanks to distributed acoustic sensing (DAS). This technique measures any tiny changes to the phase of fiber optic laser pulses that reflect from many points on fiber optics. The thing is an acoustic or seismic wave stretches and compresses fiber optics when it passes through the ground where the fiber optic is attached. DAS systems can provide the necessary information at a reasonable cost. Moreover, the usual seismometers couldn’t reach such kind of information.

In fact, Iceland is not the first country where the distributed acoustic sensing (DAS) technology was applied. Before that, fiber optic cables were produced in other seismic regions, for example, in the USA. The precise information on earthquakes’ location, nearby faults was got thanks to the fiber optics both on the seabed and on land. Scientists consider that by using a million kilometers of fiber optic cable around the world, we can broaden quake monitoring thanks to the network of seismometers with fiber optic sensors.

Distributed acoustic sensing (DAS) has been previously applied mostly in the fossil-fuels industry. The sensing technology helped to monitor boreholes and image deposits of oil and gas. Nowadays, it has many other applications for extracting data from vibration in the ground. Distributed acoustic sensing can even shed some light on global warming by studying the glaciers’ movements in the Antarctic and Alaska.

Besides earthquakes, researchers proved that they can use DAS systems for studying other natural hazards. The research team from Italy showed that they can detect the strain changes connected to the volcanic phenomena which include explosions. They also discovered seismic waves slowing through presumed fault zones on the volcano.

In the meantime, scientists from Japan demonstrated that DAS technology can monitor submarine volcanoes. The researchers measured the signals from the fiber optic cable on the seafloor. They found out that fiber optic sensors could produce coherent measurements that are needed for underwater eruptions’ recording.

Distributed sensing is an effective instrument that provides us with a lot of data that we can’t observe with the naked eye. Considering how widely fiber optic lines are used, distributed acoustic sensing (DAS) can give many possibilities to scientists and society.

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Distributed Acoustic Sensing (DAS) for vibration detection

DAS for vibration detection The thing is that human hearing is actually limited. Nonetheless, the technology of Distributed Acoustic Sensing (DAS) allows for detecting ground vibrations that are difficult to hear. Therefore, DAS systems perform analysis of seismic signals produced by people, animals, or even vehicles, etc.

To be more precise, DAS technology collects acoustic data with the help of fiber optic cables. Herewith, distributed acoustic sensing records signals and the backscatter pattern that can be analyzed later. For instance, distributed acoustic sensors can detect various environmental conditions – earthquake and hydrological activity, wind and weather events, and more.

It should be noted that virtually any fiber cable can be used as an acoustic sensor thanks to DAS technology. The thing is that it needs limited power, and the DAS is immune to electromagnetic and radiofrequency interference. This is the reason why distributed acoustic sensors can be applied for long-term, persistent monitoring in difficult-to-reach places.

The most popular DAS applications include the oil and gas industry where acoustic sensors are used to monitor pipeline leakage and seismic activities. Additionally, DAS systems perform perimeter security and smart city applications and control traffic and assets.

A company-manufacturer of fiber optic solutions from the U.S. has presented a new project for existing fiber cables. They test DAS technology to improve its sensitivity and resolution. Thus, new DAS applications would appear to offer a greater understanding of acoustic signals.

Thus, DAS helps to detect cattle movement in an agricultural experimental station. The existing fiber optic cables record four main signal types: cattle movement, earthquake and wind activities, and human traffic. Herewith, the researchers claim that it is very easy to turn existing cables into acoustic sensors of high efficiency.

In the nearest future, distributed acoustic sensors can be used for the detection of geological, hydrological, meteorological, and biological (human and animal) activity. During the tests, DAS systems have provided a greater understanding of the movements of cattle and people in the land.

Distributed acoustic sensing demonstrates a high level of efficiency. “DAS using fiber optic cables could prove to be an effective solution for monitoring the movement of livestock and wildlife and weather events such as high winds, storms, and lightning in remote locations.” Moreover, the same technique can be useful for other applications mentioned above. Even though DAS technology still needs to be improved, it is planned to be used to test new analytical techniques and devices.

Optromix is a DAS system manufacturer that provides top of the line distributed acoustic sensing systems suitable for monitoring of commerce networks. If you have any questions or would like to buy a DAS system, please contact us at info@optromix.com

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Fiber optic sensors for deformation detection

Fiber optic sensors for deformation detection The development of stretchable fiber optic sensors promotes changing the operation of soft robots and smart systems. Recently, a team of scientists from the U.S. has developed a distributed fiber sensor that uses low-cost LEDs and dyes. The developed fiber optic sensors are stretchable and allow for finding different deformations (strain, pressure, bending).

To be more precise, these distributed sensors can be applied in soft robotic systems and augmented reality technology. The fiber optic sensors offer the opportunity to feel the same tactile sensations as animals use to navigate the natural world. The ability to determine deformations(for instance, strain, pressure, and bending) makes it possible to find exact locations.

The scientists claim that such a fiber optic technology will be useful for applications in sports medicine and physical therapy. The development of fiber sensors is based on previous technology, “in which light was sent through an optical waveguide, and a photodiode detected changes in the beam’s intensity to determine when the material was deformed.” Then numerous similar sensing systems have been created.

It should be noted that the operating principle is based on silica-based distributed fiber sensors. The distributed fiber optic sensors allow for recording the slightest wavelength shifts to determine, for example, changes in humidity, temperature, and strain. Nevertheless, silica optical fibers are not efficient with soft and stretchable devices.

Herewith, it is easy to deform soft materials in difficult-to-reach areas. Therefore, scientists develop a fiber sensor that can overcome these challenges. The new fiber optic system consists of a stretchable light guide for multimodal sensing. The two cores of optical fiber are made of polyurethane elastomeric. The first core is transparent, the second has dyed.

A pair of cores in distributed fiber optic sensors increase the number of outputs. They, in turn, help to find various deformations, their exact location, and magnitudes. Compared to standard distributed sensors, new sensing systems do not need high-resolution detection equipment.

Stretchable fiber optic sensors apply small optoelectronics with a lower resolution. Thus, they have a lower cost, simple manufacturing, and can be easily installed into small systems. Moreover, it is possible to wear this fiber optic technology. For example, scientists have installed these fiber sensors in a 3D-printed glove.

Finally, this fiber optic technology allows scientists to measure tactile interactions in real life. Additionally, the team finds the way how distributed fiber optic sensors can advances virtual and augmented reality experiences. The thing is that these systems’ operation is based on motion capture, and fiber sensors can add new experiences.

Optromix is a fast-growing vendor of fiber Bragg grating (FBG) product line such as fiber Bragg grating sensors, for example, fbg strain sensors, FBG interrogators and multiplexers, Distributed Acoustic Sensing (DAS) systems, Distributed Temperature Sensing (DTS) systems. The company creates and supplies a broad variety of fiber optic solutions for monitoring worldwide. If you are interested in structural health monitoring systems and want to learn more, please contact us at info@optromix.com

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Distributed temperature sensing (DTS) in oceanography

DTS in oceanography The technology of distributed temperature sensing (DTS) is based on the application of Raman scattering from a laser beam light through optical fibers to detect temperature parameters along a fiber optic cable. The thing is that temperature resolution plays a crucial role. Herewith, this feature makes it possible to efficiently use DTS systems in oceanography.

Even though oceanographic applications of distributed temperature sensing are not new but such observations are not often. The reason is the serious challenges of deployment, calibration, and operation in oceanographic environment conditions. Nevertheless, researchers have tested the DTS system to overcome oceanographic configuration, calibration, and data processing difficulties.

It should be noted that they also evaluate temperature errors of DTS for several common scenarios. Difficult conditions influence the whole process, thus, the researchers look for alternative calibration, analysis, and deployment methods for distributed temperature sensing.

Therefore, these errors will be reduced and the successful application of DTS systems will be increased in dynamic ocean conditions. The thing is that DTS technology allows for “continuously sampling at a relatively high temporal and spatial resolution for significant duration over broad spatial scales.”

Despite distributed temperature sensing is widely applied in environmental applications, the oceanographic area remains challenging and still relatively rare. The main purpose of new DTS development is the solution to common problems present in oceanographic deployments.

To be more precise, the researchers use 2 various DTS systems, 3 fiber optic cables, and 24 thermistors. All of them help to test cables and different calibration configurations and perform distributed temperature sensing. Test results enable them to improve future oceanographic deployments. Moreover, they aid to achieve the best possible temperature signal in difficult deployment and operational environments.

DTS technology is a relatively new oceanographic tool. It allows for detecting temperature across wide spatial and temporal scales. Herewith, the application of such a fragile DTS system in remote and dynamically complex conditions remains difficult. Moreover, sometimes it is impossible to perform distributed temperature sensing at all.

Additionally, DTS systems face challenges during the detection of air/sea boundary. The reason is the change of water level, for instance, tides, waves, surge, etc., when the fiber optic cable can be exposed. Finally, the new DTS has succeeded to detect the temperature variance between the air-sea interface.

If you want to obtain a highly efficient distributed temperature sensing system, you should choose the Optromix company. Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for monitoring worldwide. Optromix is a fast-growing vendor of fiber Bragg grating (FBG) products line such as fiber Bragg grating sensors, FBG interrogators and multiplexers, distributed acoustic sensing (DAS) systems, distributed temperature sensing (DTS) systems. If you are interested in DTS systems and want to learn more, please contact us at info@optromix.com

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Distributed temperature sensors promote warning systems

DTS for warning systems Temperature is a key safety indicator in any industry. The technology of distributed temperature sensors using optical fiber allows measuring the temperature at any point in the fiber, with an interval of 1 meter, resulting in the detailed temperature dependence of all required areas. The data obtained by this technique makes it possible to develop intelligent warning systems based on it, therefore, replacing outdated point-based monitoring systems.

Operating principle of temperature sensors

The optical fiber itself acts like a fiber optic sensor, and the distributed nature of the DTS technology enables us to determine the temperature change at an arbitrary point, spreading many kilometers from it. Moreover, the measurement quality is not affected by electromagnetic radiation, thus, the distributed temperature technology is free from false alarms.

To be more precise, distributed temperature sensors (DTS) allow measuring the characteristics of an object along a fiber optic cable, while the fiber cable is a linear sensor, which is a continuously distributed sensing element throughout its entire length.

The operating principle is based on the reflectivity of stimulated Raman scattering of light (Raman effect). A semiconductor laser is also used to determine the location of temperature changes in a fiber optic cable. The fact is that the structure of the optical fiber changes when the temperature changes.

When laser beam light from the laser system enters the area of temperature change, it interacts with the changed structure of the optical fiber, and in addition to direct light scattering, reflected light appears.

Benefits of temperature sensing systems

The main advantages of fiber optic sensors in comparison with classical analogs are the following:

Compact size;
Very fast response to parameter changes in the environment;
Low weight;
Multiple parameters can be registered simultaneously by a single distributed sensor;
Reliability;
Very wide operating temperature range of DTS;
Small price per unit length of the sensing system;
High sensitivity;
Long operating time;
The high spatial resolution of temperature sensors;
Resistance to chemicals and aggressive environments;
DTS is not affected by electromagnetic disturbances;
The sensitive part of the fiber sensor does not require connection to power lines.

The processing unit measures the propagation speed and power of both direct and reflected light and determines where the temperature changes. For instance, at a wavelength of 1550 nm, a pulsed generation mode is used with a laser power limit of 10 mW.

Types of sensors for temperature measurement

There are several types of optical fibers, each of which meets certain requirements for its properties, depending on the application due to the fact that the properties of the optical fiber can be varied over a wide range.

Physical effects on the optical fiber, such as pressure, deformation, temperature change, affect the properties of the fiber at the point of exposure and it is possible to measure the environmental parameters by measuring the change in the properties of the fiber at a given point.

In general, a fiber optic sensor consists of two concentric layers: fiber core and optical coating. The fiber optic light guide part can be protected by a layer of acrylate, plastic, reinforced sheath, etc., depending on the application of this fiber cable.

Thus, distributed fiber optic sensors are perfect for industries related to combustible and explosive materials, such as coal, oil and gas production, etc. for use in fire alarm systems of various structures.

Common applications of DTS systems

Application of distributed temperature sensors includes:

fire alarm systems in the road, rail, or service tunnels;
thermal monitoring of power cables and overhead transmission lines to optimize production processes;
improving the efficiency of oil and gas wells;
ensuring the safe working condition of industrial induction melting furnaces;
monitoring the tightness of containers with liquefied natural gas on ships in unloading terminals;
detection of leaks in dams;
temperature control in chemical processes;
leak detection in pipelines.

In addition, DTS systems combined with other tools open completely new areas of application. For example, it is possible to design a specialized device – a fire detector based on a distributed fiber optic temperature sensor.

Temperature sensors for fire detection

Detecting a fire in an industrial environment is not an easy task because of the large number of disturbing factors, many of which can be considered by detectors as carriers of fire signs. In addition, dust deposited on the DTS‘ sensitive elements makes it difficult to operate and it can disable them.

It is also necessary to take into account the possible smoldering of the deposited dust, which can also lead to false alarms. The presence of fumes and aerosols makes it impossible to operate smoke optical-electronic fire detectors. The presence of carbon monoxide will trigger gas fire detectors.

Industrial facilities and production are characterized by large volumes of premises, high ceilings, the presence of long tunnels, collectors, mines, inaccessible areas, and premises with a complex configuration and geometry. And in these conditions, it is certainly possible to protect using traditional fire alarm systems, but this involves the use of a large number of detectors, and therefore they have high costs, including installation and maintenance of alarm systems and automation.

It is difficult to select detectors for explosive zones, especially for use in underground operations and mines. Aggressive media are often present in chemical industries. There are also objects of sea and river transport, characterized by the aggressive salt fog.

Oil and gas application

The use of non-electric sensing devices, the use of fiber optic cable allows the DTS to be applied in enterprises of the oil and gas complex, mines, underground operations, chemical industries (including those with aggressive environments), and metallurgy and energy enterprises.

As for oil companies, the active development of high-viscosity oil fields, which imposes strict requirements on the production equipment, and the severe depletion of most oil and gas fields require mining organizations to conduct prospecting and exploration operations, change production technologies and control the technical condition of wells.

The main task for mining companies to increase the well’s production capacity in real-time is to track information about the processes occurring in wells and fields. Solutions based on standard temperature sensors suggest well logging using point measuring instruments, which leads to the inaccuracy of the data obtained.

The disadvantages of such sensing devices include the inability to fix the distribution of one of the most important parameters of the well – the temperature profile in real-time, as well as the need for power supply, the impact on the measurement results of external electromagnetic fields, labor and time costs required for the departure of the team and performing various operations, including the immersion of the fiber sensor element and its movement along the well, data processing, etc.

DTS as a part of a fiber optic system

The fiber optic sensing system consists of distributed temperature sensors designed to measure temperature along the borehole, and a point-to-point fiber pressure sensor. Optical fibers of a distributed temperature sensing system and pressure sensors can be structurally installed in a single fiber cable.

The fiber optic cable is resistant to mechanical damage. Additional fiber optic cable protection is not required during descent and lifting operations, but the protection of the fiber cable from mechanical damage during descent and lifting operations can be provided by the use of protective coatings.

Where to buy quality temperature sensors?

Distributed temperature system provides continuous underground power lines monitoring of temperatures, detecting hot spots, delivering operational status, condition assessment, and power circuit rating data. This helps operators to optimize the transmission and distribution networks, and reduce the cost of operation and capital.

Usually, the DTS systems can detect the temperature to a spatial resolution of 1 m with precision to within ±1°C at a resolution of 0.01°C. Measurement distances of greater than 30 km can be monitored and some specialized systems can provide even tighter spatial resolutions.
The advantages of working with Optromix:

Our DTS system has the superior quality, however, its price is one of the lowest in the market;
Optromix is ready to develop DTS systems based on customer’s specifications.

If you are interested in DTS systems and want to learn more, please contact us at info@optromix.com

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Distributed temperature sensors of high precision for Raman-based sensing

DTS for Raman sensing A new distributed temperature sensor (DTS) system has been developed to perform optimization of the temperature precision with the enhanced temperature sensitivity of backscattered spontaneous Raman scattering. The DTS system is based on the difference in sensitive-temperature compensation.

Distributed temperature sensors apply the dual-demodulation, self-demodulation, and double-end configuration principles. The DTS system has been already tested and demonstrates great results: the temperature precision is considered to be 12.54 °C, 8.53 °C, and 15.00 °C along the 10.8 km under the traditional R-DTS systems, respectively.

It is possible to use the sensing system with difference sensitive-temperature compensation for the dual-demodulation, self-demodulation, and double-end configuration R-DTS, herewith, this fiber optic sensing technology enables to make the temperature precision better than 1 °C for these three demodulation systems.

The operating principle of Raman Distributed Temperature Sensor is based on “specific optical effects along the sensing optical fiber to obtain a spatially distributed temperature profile”. Compared to traditional discrete sensing techniques, R-DTS systems provide unique attributes and capabilities.

It should be noted that spontaneous Raman scattering of distributed temperature sensors uses the energy exchange in the optical fiber, therefore, when the pulsed light quantum and fiber optic material molecule leads to an inelastic collision in optical fiber, this will create an anti-Stokes light.

The thing is that the anti-Stokes light is regarded to be very sensitive to the surrounding temperature, and it allows modulating the environmental temperature using the principle of Raman scattering. Nowadays, such DTS systems find their application in the temperature safety monitoring thanks to the benefits of distributed measurement, long-distance, and high spatial resolution, as well as in transport infrastructure, smart grid and gas pipeline, etc.

It is necessary to pay on the following parameters when you choose distributed temperature sensors with high-performance: temperature precision, temperature resolution, and spatial resolution. DTS systems can be used as an industrial temperature measurement system, for instance, the carrier density in the power cable can be measured by employing a specific temperature. Additionally, distributed temperature sensors allow locating the position of pipeline leakage.

Tests demonstrate that the temperature demodulation system based on distributed temperature sensing offers higher temperature precision and resolution of the self-demodulation than the dual-demodulation system due to the signal-to-noise ratio. Moreover, the double-ended configuration for DTS systems allows avoiding the measurement error based on the change of local external attenuation.

distributed sensing DTS FBG temperature sensors

Fiber optic sensors based on the vapor deposited conducting polymer

polymer FBG sensors A team of researchers from Australia has developed a mathematical model, which is based on energy deposition and the laser-induced damage threshold (LIDT) for low-intensity light radiation resulting in the appearance of conducting polymers in novel fiber optic sensing applications.

It should be noted that nowadays polymer features are regarded as one of the most potentials and studied CP’s, herewith, the material may find numerous applications such as light-emitting diodes (OLED), optical displays, photovoltaic devices, and fiber optic sensors.

The thing is that the poly(3,4-ethylene dioxythiophene) is almost visibly transparent in its doped state, while it converts into an opaque material (dark blue) in the dedoped state, thus, making the polymer ideal for optical applications, for instance, in electrochromic devices and optical fiber sensors.

The interaction between light and the sensing material plays a crucial role in fiber optic sensing. To be more precise, there is a reaction between the sensing material and an external stimulus, therefore, it becomes possible to interrogate and measure the change, linking the optical fiber measurement to the external stimuli.

Optical fibers are considered to be an ideal example of a way to send light to a volume or point of interest for fiber optic sensing. Usually, “optical material is coated on the side or at the tip of the fiber, which are typically inorganic material”. Numerous recent sensing applications (temperature sensors, hydrogen sensors, and polymer functionalization of exposed-core microstructured optical fibers) include fiber tip fabrication and side coating.

Thus, the researchers present a new fiber optic sensing architecture based on coating the tip of an optical fiber with the vapor-deposited conducting polymer. They confirm that such fiber optic sensors enable us to study the unique electrochemical properties of PEDOT: Tos at the sub-micron length scale. Additionally, the polymer material can be integrated with optical waveguides (optical fibers as well) resulting in a range of electro-optical devices.

Optical fibers provide such benefits as immunity to electromagnetic fields, the possibility for in-vivo, and distributed measurements with the electrochemical properties of poly((3,4-ethylene dioxythiophene). Also, the researchers prepare a technique to gradually deposit PEDOT: Tos layers with desired thicknesses on the tip of optical fibers to produce such a fiber optic sensor.

Finally, the fiber optic technology was tested, and the polymer material was deposited at the tip of cleaned and cleaved SMF-28 optical fiber. Moreover, the deposition technique is based on 4 steps: “ 1. Oxidant solution preparation, 2. Oxidant coating and splitting at the tip of the fiber, 3. VPP process and 4. Washing of unbound and unreacted monomers”.

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