Tag: fiber optic sensors

Fiber Optic Sensors for Underground Coal Mines

Thanks to the fiber optic sensors, a number of fields and industries have found new approaches in safety and production processes. As a part of fiber optic technology, fiber Bragg grating sensors have proved to be an effective technique of monitoring and security insurance.

Fiber Optic Sensing Applications in Underground Mining

Underground extraction of the minerals continues to be a high-risk industry. This industry has become highly dangerous because of the permanent presence of difficult challenges. Such factors as dynamic changes, hidden defaults and seismic tremors can lead to disastrous consequences.

Due to the advancement of fiber optic technology, there is an opportunity of constant monitoring with the help of fiber optic sensing systems. Fiber Bragg grating (FBG) sensing has already demonstrated its abilities in other directions like for monitoring of the dams and bridges. For mining, the deployment of FBG sensors has become possible because of the properties they have such as high and long-term sustainability and high resistance to electromagnetic events.

This article presents the most common applications of the fiber Bragg grating (FBG) sensing in the coal industry.

Fiber Optic Sensors for Structural Safety of the Mines

Distributed sensing can be called a crucial component in the structural health monitoring of the underground mines. Previously, devices for the structural health construction monitoring couldn’t allow watching the data 24/7, and thus, respond quickly in such environmental conditions. However, today’s fiber optic monitoring systems make all this possible.

Due to the fiber Bragg grating sensors’ qualities, like reliability, they are able to constantly track the extractive activities. Moreover, thanks to their high level of sensitivity, there is a possibility to detect the slight modifications in equipment functioning and prevent severe damages at an early stage. So, fiber optic sensors are fit for mine structural monitoring as a proactive damage detection system and as one of the accident prevention strategies.

Therefore, fiber Bragg grating (FBG) sensing is able to ensure the necessary level of safety in mines. It provides the estimation of the mines’ present environment when FBG sensors collect and transmit the data remotely.

Fiber Optic Sensing for Coal Dressing Chamber Bottom Plate

Apart from safety monitoring of the roof activity, there is an opportunity to monitor changes in the coal dressing chamber bottom plate with the fiber optic monitoring systems. However such monitoring has a range of aspects that should be taken into account.

Firstly, huge equipment occupies most of part of the chamber. During the coal production it produces vibrations that may influence the stability of the mine country rock. This fact should be considered while installing fiber optic technology.
Secondly, monitoring systems should be immune to electronic interference. That is a great benefit of the fiber optic sensing, especially for the chamber, where electromagnetic interference phenomenon is strong.
Thirdly, the system shouldn’t interfere with the operation of the equipment.
Fourthly, due to the constant production around the coal separation chamber it is complicated to get accurate information.

Nowadays, fiber Bragg grating sensors can not always be applied for monitoring of the coal dressing chamber bottom plate. Still, there are some challenges that specialists can face. The lack of space, chances of inaccurate data and other difficulties can make fiber optic sensors’ setup harder or even impossible. As well as wet environments, FBG sensors are often applied in heavy environmental conditions, and specialists got used to developing such projects.

Microseismic Monitoring System as Part of the Fiber Optic Technology

Microseismic monitoring technology is an important instrument designed to prevent any dangerous accidents with the help of seismic assessment and alert about any changes.

Fiber optic sensing has also been successfully applied as a microseismic monitoring system for coal mines. The sensors were suggested to use because of their significant advantages such as large dynamic range, high sensitivity, etc.

Due to the conducted experiments, fiber Bragg grating sensors were installed in the tunnels. During the field projects they have proved to be effective by providing all the data about dynamic activities in the mine accurately. Such level of accuracy is possible due to the fact that the microseismic data are tracked over the full length of the installed fiber optic cable. The interrogation system collects the data, provides the seismic interrogation and transfers the received data. It allows improving the dynamic range and installing more fiber optic sensors. Both these factors increase the positioning accuracy of seismic events.

All in all, monitoring with fiber optic sensors in combination with the automatic processing of data can bring major benefits to identification of any changes, malfunction of mine operation and damage prevention.

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

Fiber Bragg Grating Sensors for Weigh-in-Motion strips

Nowadays, road safety has advanced to a new level with the use of fiber Bragg grating sensors. Due to its characteristics, fiber optic technology has become part of the other technologies. For example, FBG sensors are applied in WIM systems (or Weigh-In-Motion systems) for that purpose.

There are several types of WIM systems and one of them is based on fiber Bragg grating sensors. Such systems provide specialists with the most accurate and detailed data around the clock, monitoring traffic flow. They are able to detect the vehicles and in the meantime determine their weight during the regular traffic. The traffic monitoring in real time allows improving the enhancement of traffic management.

Moreover, fiber Bragg gratings (FBGs) are used in WIM systems for the structural health monitoring, for example, of the bridges or rails.

What is Weigh-in-Motion (WIM) Technology?

Weigh-in-motion (WIM) systems are based on technology that allows providing reliable weight measurements of the vehicles. The systems can be applied whether for specific road or rail vehicles such as trucks and trains, or for public applications like be set on the rail or road tracks to monitor the traffic. Weigh-in-motion systems built on fiber Bragg grating sensors measure the traffic flow and supply all the information from it. Thanks to the durability and quality of FBG sensors, the necessary data is provided using one of the most cost-effective methods.

The whole fiber optic system consists of a range of sensors and a roadside unit with all the data devices. According to the application purposes, there is an opportunity to add other fiber optic sensors to this weigh-in-motion system, for instance, temperature sensors. Moreover, to receive more data about the vehicles, it is possible to use cameras for license plate photos.

What Information do the Weigh-in-Motion Systems Provide?

Fiber optic sensors follow two basic physical principles. The first principle that belongs to fiber Bragg gratings is the diffraction changes under the deformations. The second one is the changes of the optical fibers and their characteristics under the influence of the deformation. Therefore, the WIM systems provide all the characteristics that fiber optic technology offers.

The reliable data on weight from fiber optic sensors give an understanding of the loading of heavy goods vehicles and traffic flow. FBG sensors will help in estimation, avoiding any inaccuracy in the future. This, in turn, will allow improving the goods transportation and infrastructure management.

Except for the usual weight parameters that fiber optic systems provide, there are other available options, such as date-time, speed and classes of vehicles. To efficiently operate, the fiber optic systems can be installed on the specific vehicle or placed by the road for the entire traffic flow monitoring.

Advantages and Disadvantages of the Fiber Optic Sensors

As any technology based on fiber optic sensors, WIM systems possess all the features that FBG sensors have. Such characteristics as light weight, small size and insensitivity to the electromagnetic fields and weather conditions are really important in monitoring systems. Moreover, WIM systems have an ability to identify the underinflated or double tires in the traffic stream.

Weigh-in-motion systems help in providing very short response time in operations. However, there is a possibility of some inaccuracy of weighting, especially in motion. That’s why specialists are aiming at enhancing the same level of accuracy in motion as in static. And sometimes there is no use in enhancing the fiber Bragg grating sensors’ accuracy level, but increasing the number of sensors or making the automatic calibration processes better. There is a range of external factors that influence fiber optic sensors’ operation such as vehicle suspension, road roughness, etc. Moreover, they can influence the accuracy level in a bad way.

The most commonly agreed disadvantage is relatively high cost for electronic equipment. However, due to the long service life of fiber optic sensors, WIM systems seem to be a cost-effective technique by operating for at least 10 years.

Applications of the Weigh-in-Motion Systems

Fiber optic solutions are applied for many purposes as WIM systems. If it is needed, WIM unit can provide several data parameters at once. Usually, such data is applied in the following spheres:

Vehicle and traffic loading. As it was mentioned before, the information on the traffic flow helps in optimization and planning of the road network in the future. Or the researchers frequently apply it for carrying out the studies. However, there is another implementation that can be used for the already existing infrastructure – for example, for the review of the traffic flow over the road network and its future development with time.
Weight enforcement is aimed at complying with loading regulations. This will lead to the decline of the overloading numbers that have negative implications. These WIM systems based on the FBG principles provide the most effective instrument of weight enforcement.
WIM systems based on the FBGs can also be applied for industrial use like in logistic centers or at ports. They are most commonly needed in the weight check and defining of the trucks’ axle loads. All these measures are aimed at avoiding overloads and their possible future consequences of entering the road network.
WIM systems with fiber optic sensors for the railway industry are as well effective as DAS systems described in previous articles. The most common ways of application in this sphere are the total track loading and dynamic wheel loads. In practical terms, the provided data helps in design and maintenance of the rail tracks.

In the future WIM systems with fiber optic sensors will allow creating one of the base elements of the “Smart City” concept. The FBG sensors are able to provide the system that with different types of sensors will form a complex and reliable technology. Moreover, the improvement of the weigh-in-motion systems based on the fiber Bragg grating sensors will lead to the decrease of overloaded trucks on roads.

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Fiber Optic Sensor (FOS) Technology and its Applications

Thanks to all the advantages of the fiber optic sensor (FOS) technology and its diversity of instruments, described in the previous article, there are a range of applications. Structural health monitoring of the concrete constructions is proved to be the most effective tool for management of the infrastructure, due to the latest results.

Here is a list of the most common applications where fiber Bragg grating sensors can be installed.

Bridges

The lifetime of every large bridge is several decades or hundreds of years, including the period of construction and repair stages. Despite the improved quality of the bridges’ planning, it is still difficult to accurately predict its lifetime because of the complex structures and external influence like corrosion or the natural disasters like earthquake, flood, etc.

The structural health monitoring in real time gives an insurance of the safety of bridges. According to the researchers, this fiber optic system can be applied on the different stages of the bridge construction. Most of all, these fiber optic monitoring systems are used in the operation or safety phase of bridges and extend their lifespan.

The FBG structural health monitoring systems include fiber optic sensors, multiplexers, FBG interrogators, local and remote computers.

All in all, the fiber optic monitoring systems provide the following advantages:

Control of state of metal structures;
Control of the bridge oscillation frequency;
Notifications for the personnel on screen;
Extending the bridge’s lifetime, etc.

Moreover, when we talk about the railroad bridges, it is also possible to evaluate the lower bridge beam condition.

Buildings

The state of the load-bearing structure and building foundation is a crucial element of safety. And fiber optic sensors have made a great contribution to it.

The structural health monitoring can be applied whether for the buildings under construction or for the old houses when there is a severe level of damage and degradation of materials. Unfortunately, the majority of the houses that were built before, mostly in the previous century, are particularly vulnerable to environmental actions. Basically, because there was no specific constructive detailing that would provide the age resistance of the constructions.

The degradation usually includes steel corrosion, debonding of concrete, etc. It becomes visible when the damage is greatly extended on the elements of the structure. If the moment for the structural repair is missed, it often leads to its more complex and expensive modernization. At worst, there is a need for demolition.

Mostly, fiber optic technology is used for:

Control of the strain-stress state of metal basic structures and foundations;
Monitoring of the cracks and foundation shrinkage in reinforced concrete structures;
Snow load control.

Tunnels

The structural health monitoring systems have also made a great contribution into tunnel construction.

The most important safety factor in tunnels, as in many civil structures, is the deformations. Fiber optic sensors can monitor and provide the useful data both within the construction phases and over the long term. In the long term, monitoring calls a very stable and precise system that can compare deformation measurements over long periods. In the short term, the monitoring system can measure deformations that occur for relatively short periods.

The structural health monitoring system influences the tunnels’ management and security by providing in-time maintenance and restoration. There is a problem of excessive deformations which can seldom affect the structural security, but can cause durability problems.

For example, such fiber optic monitoring systems can be applied during the highway tunnel’ construction to measure the tunnel load or to monitor railway tunnels. Besides, the knowledge of the tunnel’s behavior helps while the introduction of the modern building techniques or for the prolongation of its service life in the future.

Hydroelectric and Wind Power Plants

Fiber optic solutions have found their applications for nuclear, hydroelectric, wind power plants. Aging management of the components is directly related to their operation. Safety requirements guarantee their safe operation but still are difficult for operators to track fully. All kinds of power plants require the accurate and qualified assessment of the thermomechanical loads and other parameters that can lead to the early aging of the equipment.

Fiber optic sensing is one of the best monitoring and maintaining systems for the plants. Structural health monitoring (SHM) of hydroelectric plants, wind turbines and others gives operators real-time information of the components’ condition.

Dams

As for the dams, fiber optic technology helps in detection of the seepage flow changes in a dam structure. Dams usually face different problems connected to external loads such as water level changes, seismic disturbances, etc. Any changes in numbers can be a sign of erosion which is the most common cause of the dam failure.

Fiber optic system allows operators to get the data from all over the dam as measurements are taken along the full length of the cable. Distributed sensing detects the tiniest changes in rates that otherwise can lead to the operational failures.

Fiber optic sensors are able to measure various parameters and quantities in structural health monitoring. Depending on the required operating principles, specialists discuss which type of FBG sensor is the best suitable and their way of embedding and surface mounting. All in all, their final goal is to find the most effective fiber optic solution for the operating principle and potential applications in SHM.

The short list of applications can be also found on our website.

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Fiber Optic Sensing for the Steam Assisted Gravity Drainage

Fiber optic sensing technology has proved to be an effective method in well and reservoir management. Fiber optic sensors constantly track temperature changes along the wells at specified intervals and collect all the data.
This technique is also compliant with the other technologies such as Steam Assisted Gravity Drainage (SAGD).

What is Steam Assisted Gravity Drainage?

Steam Assisted Gravity Drainage (or SAGD) is an enhanced oil recovery drilling technique that helps in extracting heavy crude oil or bitumen from oil sands deposits. Mostly, the accustomed approaches in such cases are economically inefficient. Specialists may use it in particular cases when the production is difficult. With the help of the fiber optic technology this approach becomes more cost-effective.

How does Steam Assisted Gravity Drainage work?

In short, the SAGD system’s principle is heating the heavy oil or bitumen by the steam for further extraction. For that two horizontal wells are drilled at an angle of 90 degrees to a vertical bore well. In the wells, there are two pipes, one above the other for around 4-5 meters.

At the very beginning, the cold heavy oil is essentially immobile because of the high viscosity, and it needs to be warmed up to extract it. To do so, the steam is applied. It travels through the upper well into the reservoir and expends the heat in all directions of the formation, making a steam chamber. The heat warms the bitumen and reduces its viscosity. Then the bitumen flows downward into the production well and is pumped to the surface. Both processes are going at the same time.

Current Applications of the Steam Assisted Gravity Drainage

Due to the growing level of oil consumption, the level of its development needs to be increased. Not the last role is played by the SAGD and fiber optic systems such as fiber optic sensors and fiber Bragg gratings.

Like any exploration, heavy oil production needs accurate analysis and planning, especially if there are other factors that make the production difficult. Such aspects as great depth, high temperature conditions, etc. are essential. All of these issues need to be considered. The low mobility and high viscosity make the oil producing complicated and lead to low recovery indexes. However, due to the SAGD and fiber optic technology, there is an opportunity to maximize the recovery indexes.

For SAGD technology, FBG sensors are usually applied in wells to track the steam as it moves along the wellbore. Due to the fiber optic sensors, there is an opportunity to see the data in real time. According to the achieved data, the velocity of the steam can be identified. Besides, temperature sensors can also define the speed of the heating. The accurate settings of the temperature, pressure and steam-injection rates can lead to the operational savings. All the information can be used to plan the further work of the production operations.

Fiber Optic Sensors in Downhole Monitoring

Fiber optic sensors have proved to be effective for various parameters’ monitoring in downhole applications. Most of all, distributed temperature sensing (DTS) is applied for these purposes. Distributed sensing has demonstrated good results. It has high recommendations in the oil industry. DTS can monitor well temperature all over the fiber optic cable.

Due to the modernly developed fiber optic designs and improvement of fiber optic sensing technology, a range of issues related to downhole production have been solved. However, the harsh environmental conditions in the downhole can still bring some problems to the fiber optic sensors.

The sensors still need to cope with hydrogen in the severe environmental conditions. It has a great impact on the optical fibers. Firstly, it can cause pressure and temperature errors. The appearing errors are connected to the hydrogen diffusion into the microstructure and to the changes of the refractive index when hydrogen penetrates into micro holes and fiberglass. So the hydrogen leads to the additional Bragg wavelength shift.

With this in mind, specialists are constantly developing fiber optic monitoring systems based on fiber Bragg grating technology.

Advantages and disadvantages of the SAGD

SAGD has played a crucial role in the rapid development of the oil resources. However, as everything, this method has some pros and cons that should be taken into account.

Most Common Disadvantages for SAGD technology

Firstly, as any other technology, SAGD has its restrictions. It is not well-suited for every production area with heavy oil. It has several aspects to be fulfilled, like homogeneous and relatively thick reservoirs.
Secondly, high water and fuel consumption. To work effectively, SAGD needs a large amount of water and natural gas. Both of them are used in the process of steam production. That’s why the energy consumption is high but worth it. When all these conditions are satisfied, SAGD technology can be used. Moreover, the specialists advise using deep water sources that are not appropriate for consumption or agricultural uses. In fact, the majority of deployments’ developers follow this recommendation for environmental protection.
Thirdly, some think that SAGD technology is an expensive tool for oil production. However, specialists consider this technology as a superior alternative to reduce the high expenses and at the same time increase productivity. The reason for the cost reduction is that less horizontal wells are required to be drilled.
Fourthly, concerns about an environmental effect of the steam assisted gravity drainage (SAGD) are still a topic of discussion. However, according to the statistics, over the last 20 years the environmental analysis is getting better. It is obvious that the production of the crude bitumen and oil cause environmental consequences, but due to the development of modern cleaner extraction technologies, the situation is improving.

The Main Advantages of the SAGD technology

The main benefit of the whole SAGD technology is the improved steam-oil ratio and high ultimate recovery. Besides, the DTS systems help in optimization of the oil and bitumen production.

The other SAGD advantage is the constant evolution. Every next project makes a great contribution and brings new ideas and experiences. Meanwhile, the diversity of newly developed methods leads to new approaches to different types of oil fields.

So there are other modified types of SAGD technique:

Shaft and Tunnel Access (SATAC);
Single Well SAGD (SW-SAGD);
Multi-drain SAGD;
Fast-SAGD;
Enhanced Steam Assisted Gravity Drainage (ESAGD).

The SAGD was firstly implemented in Canada, where there are the largest reservoirs of crude bitumen. This allowed to advance the recovery factors in excess of 50%.

SAGD (steam assisted gravity drainage) well temperature monitoring provide:

Temperature profile control of injection and production wells;
Determination of inflow (injection) intervals of the fluid;
Determination of the fluid level in the well and perforation intervals;
Identification of issues in the well.

Plus, as any fiber optic technology, distributed temperature sensing for SAGD offers:

Maximum protection of the cable against chemical and physical effects;
Longer service life;
Convenience and speed of the installation;
Operations in the well without the extraction of the cable sensor.

The SAGD wells have implemented all the advantages of fiber optic sensing. FBG sensors offer real-time, precise temperature measurements along the fiber optic cable in the wellbore. Fiber optic solutions allowed us to monitor the objects that were unapproachable before. For example, fiber optic sensors with extended temperature range were applied in the oil wells for temperature control during oil production using SAGD technology.

Steam assisted gravity drainage is commonly believed to be applied for complex deployments. It aims to make the process simpler. And the fiber optic technology is good at helping it. However, the specialists should discuss and decide how fiber optic technology can fit into the development at the planning stage. Fiber optic solutions may simplify the production process.

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Fiber Bragg grating sensors for overhead transmission lines’ monitoring

Fiber Bragg grating sensors have a wide range of applications starting from the oil & gas industry and ending with structural health monitoring. However, few people know that FBG sensors are also effectively used to prevent icing on the overhead transmission lines.

According to the statistics, many countries have already faced great accidents and vast economic loss caused by the icing on the overhead transmission lines. The frequent icing load can lead to catastrophic consequences, for example, line breaks, short circuits, and tower collapses. In such disasters, thousands of people find themselves without electricity.

Fiber optic sensors VS electric ones in icing monitoring

Nowadays, there are different technologies for icing monitoring that can be produced both for individual transmission lines and for the whole energy transport infrastructure. The common ways of icing conditions estimation are dip-sag monitoring, video surveillance, non-contact infrared measurement, etc. All these methods usually can’t give accurate data on icing thickness, and they have got difficulties because of electromagnetic interference with the power supply.

Compared to the traditional sensors, fiber optic sensors improve the effectiveness of accident prevention through monitoring and control with the help of automated instruments and systems.

The main system’s features in icing monitoring are:

The system monitors the onset of icing in accordance with changes in the load and sag of the span.
The system includes an ice melting system.
The system monitors the temperature of the ground wire and switches the melting off automatically.

FBG sensors’ main advantages for icing monitoring

In fact, fiber Bragg grating (FBG) sensors have already turned out to be an excellent solution for solving all the issues where electric sensors failed. In comparison with them, fiber optic sensors apply light for change monitoring in strain, temperature, and other parameters. It means that their accuracy doesn’t depend on electromagnetic interference.

Over recent years, FBG sensors have proved to have a lot of potential in monitoring the transmission lines. Fiber Bragg grating (FBG) sensors’ advantages are:

compact size,
lightweight,
tolerance to corrosion and to electromagnetic interference,
resistance to the environmental impact,
high-temperature stability,
explosion and fire safety,
wide range of measurements, etc.

Scientists made FBG sensors able to define the accurate phase without a special reference point. Moreover, they can also suit for grid monitoring and distributed measurement.

Thanks to modern measurement methods such as distributed fiber optic sensors, a complex problem of monitoring the start of the ice formation can be solved, and there is the most effective way to eliminate it.

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FBG Interrogators with a size of a memory stick

Fiber optic sensors are a modern technology that helps in shape and temperature measurements in various spheres and industries, for example, civil structures, aircraft, medicine, etc. Scientists from all over the world aim to create the most compact and cost-effective device according to the market demand. So the specialists from Europe have produced the new memory stick-sized FBG Interrogators.

Fiber optic sensors’ nature

Fiber optic sensors have many characteristics that make them very effective for a multitude of applications. They are small, inert to chemical substances, immune to electromagnetic interference, and capable of withstanding high temperatures. There is no doubt that they have a lot of applications thanks to their unique characteristics. Fiber optic sensors are applied in structural health monitoring. In medicine, they are also used in catheters, endoscopes, etc.

Over the last years, scientists have developed fiber Bragg grating (FBG) sensors that can measure strain and temperature. For example, fiber optic sensors are successfully applied in the new generation of planes. The whole principle of the fiber optic sensors is based on the reflected light. The light is sent through a fiber optic cable and partially reflected by a microstructure inscribed into the fiber core. Researchers can observe different changes in strain or temperature thanks to the shifts in the wavelength of the reflected light.

Modern sensor devices such as FBG interrogators are based on free-space spectrometry. Spectrometers measure the properties of light in a specific part of the electromagnetic spectrum. However, this approach still has several limitations including measurement resolution, power consumption, etc. That is why scientists aim to develop fiber optic technology further.

The new generation of FBG interrogators

As fiber optic technology develops, scientists create new ways of device dimensions, power, and cost consumption to serve the increasing applications and clients’ requirements. There are many types of FBG interrogators that can include multiple photonic functions in one device. These devices represent the second generation on the market responding to the clients’ demands.

Nowadays, scientists even work on the third generation of fiber optic systems that have the size of a memory stick. With the size optimization, they also make the cost-effectiveness better. The new fiber optic technology includes a photonic submodule that consists of two light sources and a spectrometer section. Scientists have added three thermistors to measure the temperature of those three parts. The small box that has a size of a memory stick detects the reflected light that’s coming in on the fiber. The light is produced by one of the two light sources inside the model, injected into the fiber. The photodiodes record the reflections and the electronics amplify them.

Despite all the advantages of these new fiber optic systems, the future market adoption needs a more compact and lower-cost solution, including the costs of the consumables in medical and fiber optic battery monitoring systems.

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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Fiber Optic Solutions for 3D visualization in agriculture

Scientists have developed a new technology based on the distributed sensing system. They have found a fiber optic solution for 3D visualization in real-time that demonstrates crop root growth. Moreover, the newly developed distributed sensing system serves as radar and can be applied to measure temperature, acoustic, strain, etc.

In fact, in the 21st-century farmers agree that soil fiber optic sensors play a crucial role in agricultural development. Thanks to the data received from fiber optic sensors and other advanced technologies, they can easily develop more precise uses of water and other inputs.

Modern fiber optic technology in agriculture

According to recent studies, the plant root directly influences crop resilience and productivity rates. For instance, deep root architecture suits better for drought resistance. Thanks to it, it is possible to keep high crop yields even in the absence of rainfalls. In contrast, shallow root structures are better for paddy fields where there is a deficiency in oxygen. To speed the crops’ adaptation to such anticipated environmental conditions, scientists had an aim to create a system that would quickly provide data in real-time on root architecture. That is why they applied modern fiber optic technology.

The whole procedure of plant roots’ visualization seems to be difficult because it requires digging. Moreover, there is still a lack of convenient and high-resolution underground imaging systems that could help in studying plant root structures.

Fiber optic sensors for root growth monitoring

With the help of fiber optic technology, scientists prototype the newest imaging device which monitors root growth underground by using distributed fiber optic sensors. During the experiments, the fiber optic sensor was attached to a soft film and transformed into a spiral. Then a distributed sensing system was put into a pot filled with soil. As a result of the tests, scientists demonstrated that the distributed sensing system is able to detect small movements within solids even when a fiber optic sensor is placed into a film structure. This fiber optic solution provides a new approach to imaging movements in the field.

Each year researchers aim to turn farming technologies into a more automated sphere. The fiber optic sensors can help in it by providing more feedback on the soil conditions, temperature, etc. This modern device based on a distributed sensing system is an important addition to the next-generation agriculture instruments. It can be applied for data-driven automation.

According to scientists, this novel method with the usage of fiber optic sensors can also have other different applications. It can suit any small-scale perturbation occurring in solids, for instance, for monitoring worms’ movements through sediments or the propagation of mushrooms in loam.

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FBG sensors in monitoring road conditions

Scientists from Latvia made a number of experiments using fiber optic technology for monitoring the condition of the road surface. They chose special FBG sensors that can collect data about roadway changes, like changes in the strain and temperature. These fiber optic solutions that also include applying fiber Bragg gratings (FBGs) will help in designing reliable roads and planning for road repairs.

The process of pavement destroying can’t be completely stopped. However, we can apply more strong materials and repair small cracks in the structure at the early stages. That is why we require new monitoring methods and the most effective ways are fiber optic solutions.

According to the research, the fiber sensors could define the roadway defects and measure the load on the site. So with the help of fiber optic sensors, it will be possible to consider the pressure and vibration created by transport in the area and strengthen the coverage in the right places.

Scientists chose fiber optic systems because fiber optic sensors are highly sensitive and do not require a power supply. Fiber sensors can be installed in an existing fiber optic network and receive data remotely. The basis of fiber optic sensors contains fiber Bragg gratings (FBGs). It is a section in the middle of an optical fiber, where the refractive index of light has been changed using ultraviolet radiation. As a result, such a section always reflects radiation only in a very small part of the spectrum and transmits the rest of the light without loss. The fiber Bragg grating (FBG) can be formed so that the wavelength of the reflected light depends on changes in temperature, pressure, or other physical aspects. Because of these parameters, fiber Bragg grating sensors are effective for application.

Scientists placed two types of fiber optic sensors on one of the highways during its renovation. The first one measured deformations in construction, the other detected temperature. Since unprotected fiber sensors are quite fragile, they were packed in composite and ceramic tubes. The first test demonstrated that the most precise strain measurements are possible when the load is placed exactly at the location of the fiber optic sensors. Researchers also specified that temperature plays a crucial role in the deformations of the asphalt. And the final key aspect of the tests with fiber optic technology was monitoring real traffic and defining the truck’s quantity.

Finally, the experiments demonstrate that fiber optic sensors can measure the deformations of the roadway with sufficient accuracy. By applying FBG sensors specialists can determine the moment when the limit of permissible deformations will be exceeded in the selected area. That will definitely help in designing new roads and repairing the existing ones.

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Distributed Acoustic Sensing (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.

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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Fiber Optic Technology and its recent advances

During the last 60 years, fiber optic technology has been applied to improve the efficiency of developed systems in various spheres like medicine, vehicles, and other industries. Modern fiber optic solutions expand the abilities by implementing levels of data and sensing technology in the energy, medical field, and even aerospace. There are various fiber optic solutions that help researchers improve their development and make new discoveries in science.

Intrinsic and extrinsic fiber optic sensors are two wide categories of fiber optic sensors. Extrinsic fiber optic sensors utilize the fiber to manage the light to a sensing region. Then the optical signal is modulated in another environment. Talking about the intrinsic fiber optic sensors, the light remains within the waveguide. So it measures the influence of the optical fiber signal.

Intrinsic fiber optic sensor technology, where the fiber optic sensor is the fiber optic cable itself, has improved significantly during recent years. There are two main technologies connected to intrinsic fiber optic sensors: scattering and FBG. FBG methods can be fully distributed or have many sensing points. With the help of FBG sensors, scientists can define the changes by getting precise measurements. Scattering techniques depend on natural imperfections occurring in the fiber optic cable. The FBGs have a high signal-to-noise ratio in comparison with scattering techniques.

Both scattering and FBGs use different demodulation techniques. Scattering techniques get the information by observing changes in naturally back-scattering patterns. For FBG based technology, wavelength division multiplexing is the most prevalent demodulation technique. However, in certain circumstances, optical frequency domain reflectometry can become the most useful method.

Wavelength division multiplexing is able to spread to large distances and get the data rapidly. This technology can also support multiple fiber Bragg gratings on a fiber. It observes critical points more than the whole field of the data. That is why it is mostly applied in automobile crash testing as a monitoring instrument.

The scattering techniques can cover long distances and give a distributed profile of the data. They obtain information all over the entire fiber optic cable. Many systems on the market measure temperature or acoustics and are called Distributed Temperature Sensing (DTS) or Distributed Acoustic Sensing (DAS). These techniques are usually applied in monitoring a pipeline for tampering, for example, where there is no need for high-speed acquisition.

Optical frequency domain reflectometry is another demodulation technique that is mostly applied with FBG sensors where fiber Bragg gratings are placed really close and create a fully distributed sensing fiber. It has many advantages like the combination of high spatial resolution, a bunch of fiber optic sensors, a quick refresh rate, and a full distribution set. Apart from distributed sensing of a strain and temperature, this technology allows defining 2D deflection, liquid level, magnetic fields, etc.

Nowadays, thanks to fiber optic technology, scientists have an opportunity to solve any problems in their designs by using fiber optic systems. And there are still many possibilities for fiber optic technology in the future.

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