Articles

about Fiber Bragg Gratings (FBG), FBG Sensors and Monitoring Systems

A new application of FBG sensors

on November 18, 2019

FBG sensorA team of researchers offers a new application of fiber Bragg grating sensors (FBG sensors) in the construction and characterization of Micro Pattern Gaseous Detector. Such a FBG sensing system includes 144 gas electron multiplier chambers of about 0.5 m2 active area each. It should be noted that FBG technology has been applied in high energy physics only for high precision positioning and re-positioning fiber sensors due to their benefits (low cost, easy installation, low space consumption). Nowadays the most common application of fiber Bragg gratings remains the use for very accurate strain measurements in material studies.

Now FBG technology is used as flatness and mechanical tensioning sensors employed to the wide GEM foils of the GE1/1 chambers. FBG sensor array allows detecting the optimal mechanical tension applied and characterizing the mechanical tension that should be applied to the foils. A new application of FBG sensors has been already tested and demonstrated great results that can determine a standard assembly procedure and possible future developments.

Fiber Bragg gratings are considered to be a type of distributed Bragg reflector, developed by a short segment of optical fiber that enables one to reflect certain wavelengths of light and transmit all others. The operating principle of FBG sensors is based on “the creation of a periodic variation in the refractive index of the fiber core, which generates a wavelength-specific dielectric mirror”. Thus, the FBG sensing system can be applied as a strain measurement device because changes in fiber Bragg gratings lead to various light frequency responses.

One more application of FBG sensors in GEM chamber construction includes the opportunity to be applied as a load gauge for accurate measurement of the tensile load employed to the foils, of the various layers, at the same moment. The thing is that this FBG application plays a crucial role in the case of the GE1/1 chambers because the foils are stretched through screwing nuts with a dynamometric screwdriver during their assembly procedure, therefore, it is necessary to know accurately how much to strain the foils to escape to stretch them too much.

The testing of fiber Bragg grating sensors consist of proper stretching of the GE1/1 GEM stack, then the researchers removed a single stretching screw from the chamber and replaced it with an eyelet screw with installed stainless steel wire applied to set various weights. Additionally, it was necessary to add weights in different steps until they applied load achieves in the fiber Bragg gratings facing the eyelet the same response as when stretching of the GEMs occurs by the traditional screw.

Finally, the technology of FBG sensors is regarded as a highly reliable glue-less technique that offers the correct tensioning of the three GEM foils. The correct tension across the GEM stack leads to uniform gaps resulting in the required performance of the detector. Moreover, FBG sensors operate successfully as load gauges for accurate detection of the used stretching force to GEM foils.

Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for the clients. Optromix produces a wide range of fiber optic devices, including cutting-edge customized fiber optic Bragg grating product line and fiber Bragg grating sensor systems. Moreover, Optromix is a top choice among the manufacturers of fiber Bragg grating monitoring systems. If you have any questions, please contact us at info@optromix.com

read more
editorA new application of FBG sensors

Fiber optic sensors based on the vapor deposited conducting polymer

on November 11, 2019

fibre-1562702_640A 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 potential 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-ethylenedioxythiophene) 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-ethylenedioxythiophene). 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”.

Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for the clients. Optromix produces a wide range of fiber optic devices, including cutting-edge customized fiber optic Bragg grating product line and fiber Bragg grating sensor systems. Moreover, Optromix is a top choice among the manufacturers of fiber Bragg grating monitoring systems. If you have any questions, please contact us at info@optromix.com

read more
editorFiber optic sensors based on the vapor deposited conducting polymer

Distributed acoustic sensing for railway structural health monitoring

on October 28, 2019

The principle of distributed acoustic sensing (DAS) operation is based on the processes occurring in fiber optic cables. To be more precise, sound waves falling at the fiber cable change the reflection of laser beam pulses inside it. Thus, these changes are possible to be detected. 

1railway-track-2049394_640Specially developed algorithms allow converting a measurable backscatter signal trace (signature) into valuable information, for example, about moving rolling stock, about people moving along or near tracks, or other actions, such as earthmoving operations.

The application of DAS-based systems becomes widespread, for instance, in the oil and gas industry, as well as in the border protection due to these technical capabilities.

Any single-mode fiber can be quickly and easily converted into a series of “virtual microphones” by distributed acoustic sensing. This requires only minimal exposure to the ends of the optical fibers

Since the majority of railway tracks already have fiber optic cables, the above-mentioned possibilities of DAS application in the railway infrastructure can be performed to a large extent using existing resources.

If an existing fiber optic cable already laid close to the railway infrastructure is used, it is possible to monitor trains, auxiliary rolling stock, track crews, strangers near tracks or natural influences on the infrastructure. 

Accordingly, DAS technology can find application in tracking systems for the movement of trains, monitoring the track and rolling stock, as well as in the protection of railway infrastructure.

Only one set of DAS systems enables to monitor processes and components on and off track for 40 km. It is possible to combine many such units into a common sensing system to cover extensive networks of railway tracks. At the same time, the DAS system operates with an accuracy of 10 m and provides information about the location of the recorded event on the site and GPS coordinates.

Several acoustic sensing sets can be combined into a single system to control longer tracks. The possibilities of the co-use of distributed acoustic sensing and wheel hole registration systems were already studied to meet the requirements of the railroads, taking into account the considered limitations.

The application of advanced axis counters is caused by the need to detect individual axes and the train location on a particular track in compliance with safety conditions.

Unlike track circuits, directly establishing the free or occupation part of the track, the axis counting system operates indirectly. If the track part was free in the initial period, and then the number of wheelsets entering and leaving coincided, the part is registered as free from railroad rolling stock. If this condition is not fulfilled, the part is considered occupied.

The data combination from both sensing systems creates a whole variety of new possibilities by using the generated information from fiber optic acoustic sensors. This technical solution of acoustic sensing makes it possible to detect a train to a concrete track precisely. 

Also, DAS technology provides an even more accurate determination of the train length. Moreover, this combination of sensing systems offers the opportunity to localize events, for example, you can determine which axis has a slider. In this combination, DAS can also be used on sections of railway tracks with complex track development, where several parallel tracks are connected by operations.

The user interface system of distributed acoustic sensing displays in a convenient form both data received directly from the DAS system and information generated using combined technical solutions, including additional axis counters and a system for registering the wheel hole of railroad rolling stock.

Conditions detected by the DAS system and a combined technical solution are carefully classified and all received information is provided in a visual form. This serves as the basis for the planning and implementation of activities arising from the detection results.

Besides, the data collected by distributed acoustic sensing can be redirected directly to mobile end-use devices. Nevertheless, they can also be transmitted, for example, to unmanned aerial vehicles, which are sent to the appropriate location using available GPS data. Thus, the DAS system allows you to quickly respond to a variety of events.

The interference of both signals will make it possible to more accurately correlate information about the state of train components with a specific location in the future, for example, it will be easy to establish which axis has the slider on it. New possibilities are opened up for using DAS technology in complex railway tracks, where several parallel tracks are connected by operations. 

1000px-Distributed_Acoustic_SensingThe system of distributed acoustic sensing allows both monitoring of rolling stock and state track components: the DAS system completely controls the railways and the area around them. Even unforeseen events that are difficult to detect are recognized reliably.

This also applies to fractures of rails, which represent one of the main risks on the railway. This sensing system also detects electrical discharges on air-track lines due to overload, floods, stone falling, falling of trees, and mudflows. Fiber optic acoustic sensors can significantly reduce the number of costly violations of the usual operation in railway transport.

With an increase in the accuracy of event localization, conditions are created for the application of DAS technology in areas with complex track development.

The signals (signatures) recorded during the movement of trains by the axis counters and the acoustic sensors are brought together to determine the exact location.

The possibilities of using acoustic sensing technology in railways open up broad prospects for increasing the effectiveness of monitoring infrastructure and rolling stock. Thus, the DAS system provides structural health monitoring information about:

– location of the train;

– direction of the traffic;

– speed;

– time of train arrival;

– the distance between trains;

– rail break;

– slide;

– falling of stones;

– spark discharge in the contact network;

– unauthorized access;

– cable theft;

– vandalism, etc.

Axis counters provide information about:

– the state of free/occupation of a track particular section;

– number of axes on the track section;

– speed;

– direction of the traffic;

– diagnostics.

An important aspect of railway operation is safety. Security has many indications and affects numerous different areas. DAS provides a comprehensive solution to cope with several tasks – from labor protections to the protection against vandalism.

Distributed acoustic sensing offers railway operators a single solution for the protection of infrastructure and the safety of railway workers, with an extended range and high efficiency.

DAS converts measured signals (signatures) into valuable information, for example, about moving vehicles and individuals. Based on this information, messages are generated about the presence of objects or people, which can be more accurately classified due to the high sensitivity of the sensing system. It also allows for directly recognizing certain actions, for example, earthmoving on the way, and displaying the corresponding alarm messages.

Finally, distributed acoustic sensing systems will change the way that trains are monitored and infrastructure is operated soon. An integrated railway structural health monitoring system is becoming available, which opens up previously unimaginable DAS applications and allows for the implementation of the most challenging ideas in the field of train and operation control.

The use of a distributed acoustic sensing systems for the railway industry opens up wide applications for monitoring the movement of trains, monitoring the condition of equipment, protecting infrastructure and ensuring the safety of people in real-time.

Moreover, recent advances in DAS make the sensing systems cost-effective, highly precise, herewith, these acoustic sensors do not require accurate alignment resulting in tuning vibration measurement to a particular point in the optical fiber. Thus, new DAS systems promote the speed of measurement beyond the previously established theoretical limit set by the sensing distance. The technology of new fiber optic acoustic sensors is based on the application of “colored” probe pulses or linear frequency multiplexing.

It should be noted that DAS is a highly reliable technology because it continues its operation even after it has been cut. DAS has the biggest influence in the signaling area, for example,  distributed sensing helps to manage trains by control of their accurate position and motion in real-time. The technology enables to reduce journey times while increasing rail capacity and improving safety.

Of course, the distributed acoustic sensing system continues improving and the improvement will provide quantitative measurement with improved sensitivity and higher spatial resolution on longer lengths of the sensing fiber in the future.

3das_1Optromix 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

read more
editorDistributed acoustic sensing for railway structural health monitoring

Recent developments in Distributed Acoustic Sensing

on October 21, 2019

ear-2972890_640The operational principle of distributed acoustic sensing or fiber optic DAS is based on coherent Rayleigh backscattering in an optical fiber. Today the technology of acoustic sensing is regarded as a common technique for structural health monitoring of various dynamic actions in real-time. DAS applications in safety, security, and integrity monitoring systems promote a steadily growth of the fiber optic DAS market.

Fiber optic acoustic sensors offer the opportunity to measure various changes in environmental parameters provoked by numerous events over long distances. The applications of DAS technology include transportation, oil and gas, and process control systems, herewith, they continue increasing. Additionally, distributed acoustic sensing allows performing measurements of both slowly changing (for instance, temperature or static strain) and fast-changing parameters (dynamic strain or vibration) providing fast and precise monitoring in real-time.

Therefore, DAS systems for the mentioned measurements are required to pay careful attention. Despite numerous developments that have been made in distributed acoustic sensing to increase the measurement speed over short distances with high spatial resolution, measurements at long distances remain considerably slow. Nevertheless, fiber optic acoustic sensors provide interesting alternatives for fast distributed measurements over long distances.

Such developments in distributed acoustic sensing  as “use of high ER pulses to reduce coherence noise, fast denoising in the optical domain using optical pulse coding technique, generation of high ER pulses using nonlinear Kerr effect, and the identification of pulse shapes robust against modulation instability” enable to enhance the performance of fiber optic acoustic sensors.

Moreover, recent advances in DAS make the sensing systems cost-effective, highly precise, herewith, these acoustic sensors do not require accurate alignment resulting in tuning vibration measurement to a particular point in the optical fiber. Thus, new DAS systems promote the speed of measurement beyond the previously established theoretical limit set by the sensing distance. The technology of new fiber optic acoustic sensors is based on the application of “colored” probe pulses or linear frequency multiplexing.

Finally, the improved distributed acoustic sensors have higher spatial resolution due to the use of tweaking of the conventional set up to make the optical noise lower, and more accurate quantitative measurement of an external impact thanks to frequency shift measurements and direct phase demodulation techniques.

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

read more
editorRecent developments in Distributed Acoustic Sensing

Distributed acoustic sensing for phase-sensitive OTDR technology

on October 14, 2019

1000px-Distributed_Acoustic_SensingThe sensing system is a fundamental device that presents data information about the features of the surrounding environmental conditions to electronic tools. The information obtained through distributed fiber sensing is used for analytical purposes or processed and employed to take specific actions. Herewith, today distributed sensors find widespread application since they are applied in most of the human daily used items.

For instance, distributed optical fiber sensors apply light to probe a kilometer-length optical fiber employed as the sensing system. Thus, distributed sensors allow for the detection of strain or temperature variations along the fiber length. The principle of distributed optical fiber sensor operation is based on “scattering processes happening along the optical fiber, either Rayleigh stimulated Brillouin or Raman scattering”.

The characteristics of various scattering processes offer different applications to distributed sensors. For example, distributed optical fiber sensors based on Raman technology are regarded as highly efficient temperature sensing devices. Recent developments in sensing technology enable to reach a better resolution, higher bandwidth or longer-range operation.

Nowadays new sensing technique to interrogate an optical fiber applying Rayleigh backscattering process is considered to be very advanced. Such distributed sensors are based on phase-sensitive optical time-domain reflectometry (OTDR) technology, herein, they use a train of linearly-chirped optical pulses resulting in a quite simple conventionally used methodology. Additionally, distributed acoustic sensing for phase-sensitive OTDR technology provides amazing robustness against laser phase noise and a record measured sensitivity.

The technology of distributed acoustic sensing for phase-sensitive OTDR has been experimentally demonstrated a couple of years ago, based on the application of a chirped-pulse as a probe, in an otherwise direct-detection-based standard setup: chirped-pulse (CP-)ΦOTDR. The benefits of DAS systems include intrinsic immunity to fading points and use of direct detection, therefore, distributed acoustic sensing offers reliable high sensitivity measurements.

Finally, DAS technology for OTDR finds its use in diverse applications that include seismology or civil engineering (monitoring of pipelines, train rails, etc.), and new applications based on distributed acoustic or temperature sensing appear everyday. Such a distributed optical fiber sensor can operate in up to 100 km with a low cost-setup, showing performances close to the attainable limits for a given set of signal parameters.

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

read more
editorDistributed acoustic sensing for phase-sensitive OTDR technology

FBG sensors for measuring human body temperature

on October 7, 2019

thermometer-1539191_640The opportunity to measure body temperature plays a crucial role in both physiological studies and clinical investigations. New wearable sensors based on fiber Bragg grating or FBG technology offer such an opportunity in intelligent clothing for human body temperature measurement.

The main purpose of the development is the integration of FBG sensors into functional textiles to enhance the abilities of wearable fiber optic solutions for body temperature monitoring. Thus, the FBG sensing system provides the temperature sensitivity of 150 pm/°C, which is almost 15 times higher than that of a bare fiber Bragg grating.

It should be noted that fiber Bragg grating is regarded as a type of distributed FBG reflector installed in a short segment of optical fiber that reflects particular wavelengths of light and transmits all the others. The FBG technology is used here as an inline optical filter to block specific wavelengths, or as a wavelength-specific reflector.

Additionally,  FBG sensors offer great benefit over electronic sensing systems for the use in intelligent structures, civil engineering, harsh environmental conditions, built structural health monitoring system and other. Distributed temperature sensors based on fiber Bragg gratings measure human body temperature at fiver places: left chest, right chest, left armpit, right armpit, and at the center of the upper back. Herewith, the data information provided by these FBG sensors at five places is not the same because different parts of the human body have different temperatures.

The application of distributed temperature sensors based on FBG technology allows developing a sample of intelligent clothing and testing the heat transmission mechanism from numerous aspects. New mathematical model of heat transmission for the human skin, the air and clothing has been created. Therefore, FBG sensors provide the theoretical basis of human temperature measurement applying intelligent clothing with distributed temperature sensors and demonstrate the implementation of optical fiber grating into the clothing. 

Finally, the temperature measured by DTS systems can be useful to represent human body temperature in clinics. Nonetheless, it is planned to enlarge “research in intelligent clothing to cover the measuring and recording of real-time physiological information, such as human respiration, heartbeat, blood pressure, and other physiological signals.”

The biomedical application of wearable FBG sensors, which are non-intrusive, non-invasive, and continuously being monitored, is considered to become a highly potential monitoring and diagnostic devices. Thus, these distributed temperature sensors can determine and process physiological signals, extract signal characterization, transmit data, and have other basic options.

Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for the clients. Optromix produces a wide range of fiber optic devices, including cutting-edge customized fiber optic Bragg grating product line and fiber Bragg grating sensor systems. Moreover, Optromix is a top choice among the manufacturers of fiber Bragg grating monitoring systems. If you have any questions, please contact us at info@optromix.com

read more
editorFBG sensors for measuring human body temperature

Spacecraft structural health monitoring by fiber Bragg grating sensors

on September 30, 2019

space-shuttle-992_640Fiber Bragg gratings or FBGs are considered to offer a markworthy application in fastly growing aerospace industry. The FBG benefits such as phenomenal optical multiplexing make them possible to use as smart fiber optic sensors that allow them to perform structural health monitoring of airborne vehicles and maintain and lengthen their lifetime. Thus, FBG technology plays a crucial role in the spacecraft industry where tiny errors and damage can lead to death for the crew aboard.

To be more precise, fiber Bragg grating is regarded as a thin, tubular optical fiber device that includes a physical “grating” area at its core. Herewith, the core of fiber Bragg gratings is not homogeneous, it has a periodic variation in the refractive material index. The principle of FBG technology operation is based on the change in the core refractive index because of which “some light will be reflected and some will be transmitted through the tube.” Additionally, the periodic spacing of the grating influences the reflected vs transmitted wavelength of light.

FBGs demonstrate efficient operation as narrow bandwidth light filters. The FBG application includes a block of specific wavelengths and transmission of others that is similar to the mode selection that appears in laser cavities. Nevertheless, such features as pressure and strain as well as vibration and displacement also influence at the wavelengths of fiber Bragg gratings, while the temperature may lead to thermo-optic effects in the silica material that conventional FBG sensors are made from. Therefore, the mentioned FBG properties allow using them as fiber optic sensors to measure various physical effects at the same time.

FBG technology opens an opportunity to use FBG sensors to determine ultrasonic and acoustic wave signals, with a unique application in structural health monitoring of aerospace vehicles. The thing is that acousto-ultrasonic detection by fiber Bragg grating sensors is highly effective in damage detection if the spacecraft is not mobile (on the ground). Herewith, an ultrasonic actuator is required to produce the ultrasonic signals. It should be noted that the damage detection by FBG sensors is very accurate and quantitative because it allows controlling both the waveform function and the repetition of measurements.

Nevertheless, the limitations in resolution and bandwidth of conventional tools applied with fiber Bragg grating sensors, for example, optical spectrum analyzers, do not provide accuracy in high-frequency detection. It is necessary to use a demodulation method to interpret the detected signals for accurate detection of ultrasonic waves. Herewith, the installation technique of the fiber Bragg gratings is also important in ultrasonic detection. The installation of the fiber Bragg grating sensors into an aerospace vehicle or craft require the use of various techniques. For example, it is possible to place FBGs into composite materials, however, it may cause signal distortion. This is the reason why a better way is gluing FBG sensors on with some adhesive, such as epoxy. 

Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for the clients. Optromix produces a wide range of fiber optic devices, including cutting-edge customized fiber optic Bragg grating product line and fiber Bragg grating sensor systems. Moreover, Optromix is a top choice among the manufacturers of fiber Bragg grating monitoring systems. If you have any questions, please contact us at info@optromix.com

read more
editorSpacecraft structural health monitoring by fiber Bragg grating sensors

FBG accelerometers for railway structural health monitoring

on September 23, 2019

train-821500_640New improved accelerometers based on fiber Bragg grating or FBG technology by fiber optic sensors allow performing railway structural health monitoring in both frequency and acceleration range. Such FBG accelerometers provide such advantage as immunity to electromagnetic interference, herewith, the fiber accelerometer offers multiplexed data information along very long lengths of a railway or pipeline for the in situ single-headend measurements of such parameters as vibration, strain, temperature, and fault locations or other challenges.

Thus, distributed sensors based on fiber optic technology are considered to be a better sensing device for structural health monitoring, compared to other sensing systems. It should be noted that FBG accelerometer systems are able to perform “perimeter security and other applications where events span frequencies <700 Hz and acceleration shock values of <30 G with sensitivities of about 16 pm/G” among various fiber optic sensing systems.

Nevertheless, the application in railway structural health monitoring requires optical fiber sensors that offer a higher level of acceleration peak value and broader frequency ranges. The developed optical fiber accelerometer offers the following parameters: >40 G acceleration values, 8 pm/G sensitivity for frequency values up to 1 kHz and the device is operable up to 2.5 kHz. The developed fiber optic sensor was already tested in a railway application and demonstrated successful results.

Additionally, it is possible to change the optical fiber cross-section to make the stress-induced measurement optimized, depending on the required parameters. For example, this FBG accelerometer has a commercially available length (about 0.35 m), a 15 mm diameter,  50/50 splitter (3 dB coupler), a 56 g stainless-steel mass (25 mm diameter, 15 mm height).

The principle of FBG accelerometer operation is based on the lateral forces cause birefringence changes that directly correlate with force parameters, such as vibration. Therefore, FBG accelerometer installed on a moving train enables to monitor the reflection spectrum in real-time to determine various problems with the track of a railway such as cracks, corrugations, or weak points. 

Finally, the developed microstructured optical fiber used in new types of FBG accelerometers increases the level of measurement sensitivity of available systems up to 5X, and it is planned to apply the optical fiber to manufacture additional FBG accelerometers for field tests. Herewith, the FBG accelerometer is regarded as a highly important sensing device in an all-optical fiber sensing network that offers a great amount of data information resulting in efficient structural health monitoring of railways.

Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for the clients. Optromix produces a wide range of fiber optic devices, including cutting-edge customized fiber optic Bragg grating product line and fiber Bragg grating sensor systems. Moreover, Optromix is a top choice among the manufacturers of fiber Bragg grating monitoring systems. If you have any questions, please contact us at info@optromix.com

read more
editorFBG accelerometers for railway structural health monitoring

High resolution distributed temperature sensing

on September 16, 2019

Maxdetect_Humidity_and_Temperature_Sensor_-_RHT03_10167The fiber Bragg grating distributed temperature sensing on gas-insulated line spacer influences surface charge accumulation. Nevertheless, it is very difficult to perform the DTS measurement because the traditional electric sensors have huge dimensions, they are difficult to multiplex and highly sensitive to electromagnetic interference.

Thus, a distributed temperature sensing system of the GIL spacer based on the technology of the optical frequency domain reflectometry was designed to solve the challenges. The operation of the DTS system is based on the ultra-weak fiber Bragg grating or FBG technology to change single-mode optical fiber because of its higher signal-noise ratio.

It should be noted that the distributed temperature sensing also used the demodulation technique to compensate for the nonlinear frequency tuning errors caused by the unstable tunable laser. Therefore, the DTS system allows determining the connection between the space temperature and the wavelength shift during the calibration test.

Additionally, the distributed temperature sensing includes the application of the data processing technique for 3D surface temperature on a cone-type spacer. Finally, the DTS system based on FBG technology enables to obtain efficiently high-resolution temperature measurements on the spacer surface with the help of the optical frequency domain reflectometry, which is virtually impossible to perform with the traditional electric temperature sensing systems.

Nowadays the technology of direct current transmission with the gas-insulated line is an effective way due to its low electrical losses compared with, for example, AC transmission. That is why the distributed temperature sensing is considered to be a key factor that should be known first.

To be more precise, the disadvantages of traditional electric sensing systems such as dimensions, multiplexing, and sensitivity to EMI are solved by optical fiber sensing in electrical engineering. Fiber Bragg grating technology is a precise optical temperature sensing technique widely applied. But there are some limits in the multiplexing ability of conventional FBG sensors.

The new distributed temperature sensing system includes ultra-weak fiber Bragg gratings providing a reflectivity of only 0.1% compared to the conventional FBG sensors. Compared to the optical frequency domain reflectometry based on the Rayleigh technology, “ultra-weak FBG can achieve higher signal-noise ratio since the reflection of ultra-weak FBG sensor is much higher than the backscattering in the optical fiber”.

Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for the clients. Optromix produces a wide range of fiber optic devices, including cutting-edge customized fiber optic Bragg grating product line and fiber Bragg grating sensor systems. Moreover, Optromix is a top choice among the manufacturers of fiber Bragg grating monitoring systems. If you have any questions, please contact us at info@optromix.com

read more
editorHigh resolution distributed temperature sensing

Fiber optic solutions for conveyor health monitoring

on September 9, 2019

mining-excavator-1736293_640A company from Australia offers a novel fiber optic solution that allows providing conveyor health monitoring by applying real-time data to rationalize production and on-site performance, improve occupational health, hygiene, and safety management, and implement new predictive maintenance and support capabilities to control management.

Thus, the fiber optic technology was tested in surface and sub-surface environments of some of the world’s largest mining companies and bulk material handling the equipment resulting in the accessibility of optical fiber sensing for present sale all over the world. The fact is that efficient conveyor systems are highly important because the profitability of mining companies depends fully on such fiber optic sensing systems.

Additionally, the mining industry has always a huge challenge of conveyor maintenance, and traditional sensing technologies for advanced conveyor failure detection are often precarious, subjective, they require many time and labors. The new fiber sensing system combines the technology of optical fiber detection with a sensing technology platform, “advanced signal processing algorithms and predictive analytics” enabling to acoustically monitor and check conveyor health. 

The advantages of presented fiber optic solution include the provision of accurate data to maintenance technicians, site personnel, regional operational hubs, and global headquarters, the opportunity to obtain daily asset reliability reports from every conveyor, at every site worldwide due to the connection of the fiber system to 

a wireless Internet.

The operation of the fiber optic system is based on the transmission process of short laser beam pulses along a single optical fiber cable installed along the length of a conveyor, while acoustic disturbances from the conveyor sensing system lead to tiny changes in the backscattered laser beam light, which is then classified into distinguished parameters.

Also, the obtained data is then processed, the following information is gathered:

  • the detection of a damaged ball or a broken cage in a ball race;
  • monitoring and “tracking idler bearings as they progressively wear”;
  • the prediction of potential bearing seizures and establishment of roller replacement priorities at the next maintenance shut down.

Finally, the fiber optic technology of distributed acoustic sensing is considered to be “the way of the future for conveyor health monitoring”. Such fiber optic solution successfully optimizes conveyor operation and provides essential cost savings for operators. Herewith, this fiber sensing system monitors the condition of every conveyor roller that can contain 7.000 bearings per kilometer.

Optromix is a manufacturer of innovative fiber optic products for the global market. The company provides the most technologically advanced fiber optic solutions for the clients. Optromix produces a wide range of fiber optic devices, including cutting-edge customized fiber optic Bragg grating product line and fiber Bragg grating sensor systems. Moreover, Optromix is a top choice among the manufacturers of fiber Bragg grating monitoring systems. If you have any questions, please contact us at info@optromix.com

read more
editorFiber optic solutions for conveyor health monitoring