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Fiber Bragg Grating (FBG) Sensors for Railways

Fiber optic solutions for monitoring systems in the railway industryFiber Bragg grating sensors characteristicsFiber Bragg grating sensors in field projects

Fiber Bragg grating (FBG) sensors have already been applied in various applications and still arouse great production interest. They are commonly used in structural health monitoring for aerospace, civil engineering, oil & gas, etc.

As for the railway industry, fiber optic technology has made a substantial contribution to its development. It is anticipated that within a few years the number of goods that will be transported by railways will be increased, as well as the number of passengers. This, in turn, will lead to the growth of the axle load and trains' faster speeds operating.

That's why there is a great need for a full understanding of the rails' structural and operating conditions as well as for providing safe and reliable operating conditions. So modern innovative technologies are required. Fiber optic solutions for monitoring systems in the railway industry

In railways, common monitoring systems use strain gauge sensors. The sensors constantly measure resistance caused by the stress transmitted by the rail when the train runs through it. This fiber optic technology is already prominent due to its effectiveness. However, it still has several shortcomings. For example, it is expensive, huge and has difficulties in usage, in comparison with modern FBG sensors. Moreover, the most important disadvantage is that they can be affected by electromagnetic interference. FBG sensors are immune to the external interference such as electromagnetic interference, lightning and many other external disturbances.

Because of this, fiber Bragg grating sensors are getting more and more applications in high-speed railway networks. Applications are train weight estimation, measurement of train speed for real time, wheel imbalance detection, etc. It is clear from experiments that FBG sensors are more appropriate as railway monitoring systems compared to electrical ones. Fiber Bragg grating sensors characteristics

FBG sensors provide many crucial features for unique operational conditions in railways. In comparison with usual electrical sensors, fiber Bragg grating sensors have EMI/RFI immunity, multiplexing capability and can offer interrogation for long distances. In FBGs the data is wavelength-encoded, which makes the signals less susceptible to intensity fluctuations. Moreover, the fiber optic cable can be interrogated from either end, offering redundancy to FBG sensing networks. Plus, FBGs have a self-calibration capability. The strain and temperature measured findings is an absolute parameter. So there is no dependency on the measurement value and losses between the interrogation unit and the FBGs. To fabricate FBG sensors, FBGs are packaged and transformed into different types of transducers. That makes it possible to install them on the rail track fasteners, clips, bogie, train body, chassis, and axle boxes of a train to provide ongoing inspection for health checking.

In addition to that, FBG sensors can be interrogated at very high-speeds.

Providing reliable operational conditions, fiber optic designs can measure a wide range of other parameters such as inclination and acceleration through the modulation of light in reaction to the environment. Therefore, one FBG interrogator can work with a lot of FBG sensors to measure many options at the same time at different locations over the vast territory. The sensing signals can be read at distances more than 100 km away.

These features are especially useful for the railway industry because they allow simplifying the installations a lot and reducing costs. Fiber Bragg grating sensors in field projects

Over the past few years, specialists have safely held a number of field trial railway projects involving FBG sensors. For example, in 2007, about fifty FBG-based vibration sensors were installed along the East Rail Link that connects Hong Kong and Mainland China. Then fiber optic solutions were applied in metro lines of Hong Kong, part of the Beijing-Shanghai High-speed Rail Link, and in Delhi Airport Metro Express Line.

In Hong Kong this fiber optic technology was applied on a passenger rail system as a structural health monitoring system. The FBG sensors were attached to the bottom of the carriages. The goal was temperature and strain measurement. The fiber optic system supplied all the necessary data including rail tracks' and carriages' deformation. The acquired information helped to assess the rates of the corrosion and bearing wear.

According to the results, due to FBG sensors, costs of maintenance were greatly reduced. Moreover, it helped to avoid or prevent problems at early stages due to the early detection of excessive vibrations. All these works showed that FBG sensors are superior in comparison with conventional sensors in many essential aspects.

Nowadays, fiber optic solutions are regarded as one the most cost-effective technology that helps in monitoring the condition and structural health of the carriages, tracks, and under frame equipment in railway systems. There are still some parameters that need to be improved, like the lack of proprietary and custom specifications. However, in the future major railway operators can apply modern FBG sensors, gaining more field experience.

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 [email protected]

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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.

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 [email protected]

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Fiber Optic Sensors for the Structural Health Monitoring

Structural health monitoring or SHM is a crucial technique thanks to the development of architectural design. Its main goal is ensuring safety for the civil infrastructure. Due to the fiber optic sensors' benefits, a great number of the distributed sensing systems have found application in civil engineering as SHM systems.

What is a Structural Health Monitoring System?

Structural health monitoring is a technique of evaluating and monitoring structural health. Thanks to its capability to respond to unfavorable changes, this method is widely used in many fields including aerospace, civil, and energy sectors, etc.

Why is SHM necessary?

All structures are vulnerable to various internal and external factors that can lead to wear or malfunction. There are various reasons that can cause it. For instance, deterioration, problems in construction process, an accident or environmental load, etc. That's why it is important to implement a monitoring system.

Damage identification systems monitor all the changes in rates in real time 24/7. It gives an opportunity to detect deviations quickly and react properly in a short period of time before significant damage is caused. Therefore, timely maintenance and repair actions reduce the repair time and operating costs.

The structural health monitoring systems provide the following benefits:

Increased security;

Detecting of the damages at an early stage of difficulties;

Continuous tracking;

Saving of operating costs and time;

Development of rational management and maintenance strategies, etc.

Typical Fiber Optic Sensors

In accordance with the increase of the number of buildings' and bridges' under construction, the health monitoring of the concrete structures has become a topical issue.

1. Temperature Sensors

Most of all, the health of the concrete structure depends on the temperature influence. Its monitoring influences the general quality and thermal resistance of the entire structure.

At early stages, the temperature shifts affect structure' cracks and thermal stresses that are usually caused by hydration. Besides, with the help of the two crucial parameters, the maximum temperature and the temperature trend, specialists predict the future structural health.

In addition to that, there is a special system called Distributed Temperature Sensing (DTS) that helps to monitor the cracks that may appear in the concrete structures. Its low cost and well-considered technology are believed to be important advantages in measurement. Other advantages of the FBG temperature sensors are their accurate measurements and fast response. Besides, temperature sensors are perfect for hard-to-reach places and massive sensing networks.

2. Strain Sensors

Another popular type of the fiber optic sensors is FBG strain sensors. To find out the deformation degree, the structure's density information is used. In fact, the stability of the structure depends on its strength. It is safe when the structure strength is greater than the applied pressure.

After calibration, the unit acquires the features of a force transducer. The strain sensor transfers the component strain accurately. Characteristics such as light phase, frequency, amplitude, or polarization state, allow operators to monitor the health of the structure. All these features change under the influence of deformation.

Due to the common features of the strain sensors, like small size, they are universal sensors for force and load control. They are often used in large machines and steel constructions where there are high loads. 

3. Displacement sensors

The other type of sensors are displacement sensors the main task of which is displacement measurement. It becomes possible by the constant measurement of the distance between the sensor and an object.

These FBG sensors are frequently used because they are greatly resistant to external impacts like corrosion and electromagnetic interference. Moreover, they are applied where long term reliability and safety are demanded.

If we compare them to the strain sensors and temperature sensors, FBG displacement sensors can’t measure quantity using only fiber optic sensors. They utilize FBG response to its equivalent Bragg wavelength.

Displacement sensors are perfect for monitoring of the civil engineering structures 24/7. They are suitable for monitoring aircraft, concrete structures and other industrial applications.

4. Pressure sensors

FBG pressure sensors use reflected wavelength analysis. This kind of sensors measure various parameters under severe conditions like high temperature or pressure rates.

The fiber pressure sensor' operational principle is based on the fact that external factors affect the Bragg wavelengths by influencing the pressure sensor. In such a case, changes of the FBG's physical or geometrical properties are implicitly measured.

FBG pressure sensors have the same characteristics as the other fiber optic sensors. They are small, portable and provide the highest accuracy and stability.

Usually, fiber pressure sensors measure the levels of liquids and gas in pipelines or tanks. They are used for the indirect flow control in tanks and pipes. FBG pressure sensors are crucially essential in various industrial fields like liquid level monitoring in oil storage tanks, gas turbine engines, etc.

In conclusion, we should say that any of these fiber optic sensors can perform measurements as a structural health monitoring. According to the existing situation and characteristics, the specialists choose the suitable variant, thus ensuring safety for any kind of civil construction.

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 [email protected]

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Fiber optic solutions for smart cities

The topic of a smart city and how it should be implemented is one of the most discussed today. The problem is everyone understands something different by this term. However, all people agree on one thing — the advent of the era of “smart cities” is inevitable. 

First of all, the smart city is a modern urban management system, convenient transport, efficient fiber optic solutions, developed internal procedures of the urban environment. They also include modern channels of interaction with residents, infrastructure, big data, etc.

Additionally, the smart city is a big amount of data that is structured, accessible, and properly secured. When these factors are combined and managed, then the smart city will appear. 

Components of smart cities

The elements of the smart city, in general, contain smart energy, a resource supply system, smart transport and security system provided by fiber sensors, a system of social services, and urban management. Only when all these parameters come together, this is a full-fledged smart city, not its elements.

In the smart city concept, the conventional infrastructure of housing and utilities is equipped with modern fiber optic sensors. Herewith, controllers and video cameras, connected to broadband networks and integrated with a platform for data collection and processing are installed too. 

All this data is analyzed and allows achieving great efficiency and optimization of city services and local businesses, whether it is the expenditure of resources or the management of passenger traffic.

In theory, everything looks simple, but in reality, there are a lot of obstacles. Those who develop the ideology of a smart city have to face a lot of barriers, both typical for large IT projects and individual ones. This fact seriously complicates the process.

Cities must meet one common requirement to become smart: to collect reliable information (from fiber optic sensors). Based on data it is possible to develop fiber optic solutions for the long term because data is crucial in our time.

If you integrate fiber sensors into the city's infrastructure and create new data collection points — including from citizens with their mobile devices — the smart city administration will be able to analyze big data to more accurately track and predict what is happening.

This is also evident in the deployment of communication systems: local fiber optic networks, municipal Wi-Fi, specialized applications for specific tasks (smart parking, street lighting, waste disposal, and recycling).

As already mentioned, the concept of a smart/safe city includes components from a wide variety of areas of life. Moreover, the consumers of these elements are both business and government organizations, as well as the residents of cities themselves. 

Smart transport as a component of smart cities

In large cities, we are used to applying intelligent traffic analysis and route planning services. These services are based on fiber optic solutions for the collection and processing of data on vehicle movement. Nevertheless, the concept of smart transport is much broader. 

Equipping vehicles with location and speed fiber sensors, as well as video cameras, allows solving a variety of tasks. For example, they provide security to logistics management. Fiber optic sensors allow detecting where the car is, what it does and how it can plan its further route.

The development of smart transport will lead to the emergence of a full-fledged autopilot for private cars. However, there are a lot of technological and legal issues to be resolved, so whether this will happen shortly is not clear.

Smart fiber sensors for security

One of the most popular and well-developed features of smart cities today is security (in the context of protection from crime).

The streets of cities around the world are equipped with video surveillance cameras connected to a single fiber optic system for collecting and processing information, which reduces the volume of crimes.  But video surveillance is just one part. 

Smart policing is an attempt to transform a familiar service into a more effective law enforcement tool in the face of increasing population density. There is a huge layer of fiber optic technologies that the average user simply does not notice. In addition to the video surveillance system itself, this may include:

● new communication tools that allow quickly receiving information about incidents;

● modern emergency notification systems for employees and the public;

● equipment (sapper robots, drones, etc.) that allows replacing people when they have to solve dangerous tasks or improve search and other activities;

● data collection tools that can be used as an evidence base (audio recording, etc.);

● fiber optic systems for analyzing all kinds of data that allow identifying atypical human behavior or infrastructure failures at an early stage.

In the future, the concept of smart police implies the creation of centers, where all the information is collected by the fiber optic systems, especially from critical areas. Seeing the whole situation, emergency services can make decisions more quickly.

Smart resource consumption

It is obvious that accurate accounting of resources consumed allows managing the load or making savings. Therefore, it is necessary not only to implement fiber sensors in all areas of housing and communal services but also to collect data in a single platform for centralized management. On the scale of the entire country, this is a task for years and it requires billions of dollars in budgets.

There are examples of cities around the world that are actively implementing smart resource consumption. In particular, Barcelona has introduced automated structural health monitoring of street lighting, taking into account the time of day and weather conditions. Taking into account favorable environmental conditions, solar energy is actively used here for heating water in buildings, as well as powering interactive displays of public transport stops. Nowadays a modular open-source platform is being developed. It collects and analyzes information from fiber optic sensors for the consumption of basic resources, weather fiber sensors, ambient noise, etc. 

Other areas as part of the smart city

Smart education and health care (as well as other areas — mass events and tourism) allow not so much to save money but to improve the quality of life in the city.

Broadband networks make it possible to significantly expand the audience listening to a particular training course. For this purpose, educational facilities are equipped with electronic boards and cameras, as well as remote presence systems. This allows solving different tasks at different levels of education — from providing compulsory secondary education to low-mobility citizens to remote higher education in the country's leading universities.

Similar fiber optic systems in medicine allow helping patients in hospitals on the outskirts or in the regions, using the advice of more qualified specialists from the center. For example, it can be performed by a mobile carriage with diagnostic devices, a computer, a video camera, etc. 

It is worth noting that the division of industries in this list is very conditional. Many tasks are solved at the intersection of, for example, resource analysis and logistics. 

The routes of cars that take out the garbage are planned not according to a schedule, but taking into account the data from the fiber optic sensors. They detect the fullness of garbage containers that arrive at the coordination center in real-time.

Besides, some ideas combine fiber optic solutions from several areas at once. For example, they include smart office buildings that are part of a smart city. 

The main problems of implementing smart sensors

From the business point of view, there are several serious obstacles to the development of real projects within the framework of the smart city concept, which still need to be improved.

Individual components of the smart city have been developing in different cities for a long time. The main problem is the payback period for projects. 

Therefore, the first task is to increase the level of security in cities, obviously, through the introduction of video recording systems and video analytics provided by fiber sensors. It allows automatically cut off a large part of street crimes. This is the most understandable task: it is clear how to fiber optic technology and why it is necessary, it is easier to justify the costs.

In general, local specifics are extremely important for the smart city project, because people think differently in every city in the world, they have different needs and problems.

The issue of the security of the smart city system itself requires special mention. After all, every smart fiber sensor or device can become an entry point for intruders. The sensor software can be modified so that if there are “defects” in the security system, it will perform completely different tasks. 

Usually, all fiber optic sensors are made in the dust- and moisture-proof coatings, equipped with batteries with a long working time, and support data transmission over the network.

Types of fiber sensors for smart cities

Fiber optic sensors are terminal components in the following systems:

● smart parking;

● smart garbage;

● smart road signs.

Finally, it is necessary to pay attention to the fiber sensor for monitoring the position of manhole covers and the water level sensor, which allows measuring the water and its volume in any tank.

Smart cities are predicted to have a great future. However, when it will come, it is not yet clear. The thing is that technologically, everything is ready for this. There are Big Data analysis tools, appropriate server equipment, fiber sensors that can work for ten years without recharging the battery, and appropriate communication standards. Nevertheless, this market has a lack of technological stability — the final choice of dominant standards and the formation of business models. All these help to understand how you can work and earn money here. 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 [email protected]

[optromix]

Special optical fibers: the overview

At present, optical fibers are widely used not only in fiber-optic data transmission lines but also in various fiber optic cables and sensors of physical quantities and other fiber-based devices. The specifics of this application require the creation of optical fibers with special properties. 

The main purpose of special optical fibers is to perform various operations with light signals (amplification, modulation, filtration, etc.), as well as the operation of fibers in special modes and conditions (for example, under high mechanical loads – shock or

static, high temperature, radiation, humidity, UV, average IR, and far-IR ranges), so the requirements for optical losses in such fibers fade into the background. 

The typical length of special optical fibers is not kilometers, as, in the case of long-distance fiber cables, it achieves from one to several tens of meters. Today, manufacturers of fiber optic solutions note a growing interest in specialized fibers for use in optical components. 

For example, global consumption of special optical fibers in 2007 amounted to more than $ 1.2 billion. Many manufacturers of special optical fibers are expanding their customers in the field of biomedicine, aviation, input/output, and military industries. Other manufacturers see more opportunities for using special fiber optic cables in sensors and fiber optic gyroscopes. 

Nevertheless, the use of special optical fibers in communication systems has made more significant progress and promises many new opportunities. It is already clear that in any case of further development, special fiber cables will be used in the equipment of next-generation communication networks.

Currently, there are about twenty types of special optical fibers that differ in their design characteristics and basic properties. The following basic information about some of the widely used special optical fibers is provided based on the most important areas of their application in communications. 

Optical fiber for lasers and amplifiers

Ytterbium fiber with a double-clad is used in high-power radiation sources and amplifiers. These fiber optic cables are designed to meet the requirements for high-power amplifiers, industrial and military lasers, and infrared sources. 

The optical fibers are specifically designed to effectively combine a single-mode signal and high pumping power from a multimode diode into a passive double-clad fiber. The combination of low-cost, high-output multimode diodes with these fibers allows for easily achieving multi-watt power levels with an effective ratio of electrical power to optical power. 

These fiber cables have a multimode core that corresponds in size to the diameter of the inner clad of the ytterbium fiber used as an active element for fiber lasers and amplifiers. They are used to transfer radiation energy from the optical pump source of a fiber laser (or amplifier) to its active element and deliver laser output radiation for various applications.

Optical fibers for optical multiplexers and demultiplexers

Optical multiplexers and demultiplexers of an input/output are typically created with the use of photosensitive fibers. The ability of an optical fiber to change the refractive index of the core under the influence of light is called the fiber's photosensitivity. 

Photosensitive fibers are used to create fiber Bragg gratings, which are the main component of radiation input-output multiplexers and demultiplexers. A fiber Bragg grating is an optical fiber with a periodic change in the refractive index along with its core. 

By irradiating a photosensitive fiber with a laser beam through a phase mask, a fiber Bragg grating can be created. The main property of this grating is the reflection of light propagating through the fiber in a narrow band that is centered around the Bragg wavelength.

Optical fibers for modulators

There are two types of optical waveguide modulators: planar and fiber. Both types are most often phase modulators. Thus, both polarizing fibers and conventional optical fibers are used in these modulators. 

Optical fibers for filters

Currently, there are numerous types of optical fiber filters: filters on diffraction or Bragg gratings, Fabry–Perot and Mach–Zander filters, etc. 

For example, a Bragg filter is a photosensitive optical fiber with a Bragg grating formed on part of it. If you change (control) the period of the FBG filter, it becomes a tunable filter. The grating period can be changed by heating or mechanical stresses.

Optical fibers for dispersion compensation

Dispersion compensation can be performed using several methods. For example, special fiber cables or dispersion-compensating modules can be used.

These fiber optic cables have a large negative dispersion, as well as a negative slope of the dispersion curve. A wide range of operations can be performed using fibers that compensate for dispersion. The second example of dispersion compensation is fiber Bragg gratings with a variable period.

Optical fibers for supercontinuum sources

Photonic crystal fibers are a special example of special optical fibers. Thanks to the appearance of a series of unique properties, they are used not only in optical communication, but also in high-power transmission, sensitive sensors, non-linear devices, and other areas.

Manipulating the type of grating, its step, the shape of the air channels, and the refractive index of the glass allows for obtaining properties that do not exist in conventional fiber optic cables. For example, nonlinear properties make photon-crystal fibers capable of generating a supercontinuum, i.e. converting light of a certain wavelength into light with longer and shorter waves. Thus, it is possible to create broadband light sources based on new principles. 

Fiber optic amplifiers

It is known that the optical signal is attenuated by 10-20 dB at every 50-100 km of fiber optic cables. This fact requires compensation. Previously, the only way to compensate for losses in the line was the use of regenerators in the existing communication lines.

Currently, three types of optical amplifiers have been developed for fiber optic systems: semiconductor optical amplifiers, fiber amplifiers based on rare-earth ions (for example, erbium), and Raman fiber amplifiers. 

The most widespread use is currently found in optical fiber amplifiers. The current level of technology development allows for employing various impurities into quartz fiber, in particular, rare earth elements. Erbium optical fiber amplifiers are the most common at present.

Advantages of erbium fiber amplifiers include:

– high energy transfer from the pump to signal > 50 %;

- simultaneous amplification over a wide range of wavelengths, i.e. they are suitable for WDM systems;

- output limit greater than 10-25 dB / m;

– the gain time constant is large enough for overcoming modulation interference;

- low noise factor;

– polarization independence (which reduces loss);

- the opportunity to use these optical fibers in remote systems;

- the erbium amplifier can also operate in the S and L ranges.

The disadvantages of erbium fiber amplifiers include:

- large dimensions of the erbium amplifier module;

- the inability to integrate with semiconductor devices;

- amplified spontaneous emission (ASE);

– crosstalk;

- gain limit. 

Raman fiber amplifier

Raman amplifiers are promising for use in fiber optic systems due to their following fundamental advantages: they can amplify at any wavelength; the fiber light guide itself can be used as the active medium of Raman amplifiers; the gain spectrum of these amplifiers depends on the pump spectrum (wavelength), so the selection of pump sources can form a very wide (more than 100 nm) gain band; Raman amplifiers have a low noise level.

The main disadvantage of Raman amplifiers is their low conversion efficiency, which requires the use of a fairly powerful continuous pump radiation to obtain the typical signal gain of 30 dB for fiber optic systems. 

Double-clad activated optical fibers

An appropriate pump is required for any laser to work. In particular, fiber lasers use optical fiber pumping. It is proposed to use double-clad optical fibers to increase the output power of fiber lasers and simplify the input of radiation from semiconductor laser diodes into the fiber light guide.

Photonic crystal activated fibers

Recently, photonic crystal fiber-based lasers have been rapidly developed. Photonic crystal waveguides and optical fibers are a new type of waveguides. Their appearance is associated with the creation and research of new fiber optic systems – photonic crystals. They have the following distinctive features in comparison to conventional fibers:

- high numerical aperture;

- large core diameter, which can support the single-mode operation. As a result, high pumping powers and generation without noticeable heating can be realized in photonic crystal fibers;

- the absence of non-linear effects;

- high anisotropy of the optical fiber structure, allowing transmission of radiation with a high degree of polarization. 

Anisotropic single-mode fiber cables

Along with the long-distance lines, fiber optic cables are widely used in a wide variety of measurement, diagnostic, and highly sensitive monitoring and control systems. Anisotropic single-mode optical fibers promote the development of sensors for measuring various physical quantities and such unique devices as fiber optic gyroscopes. 

Many manufacturers of special optical fibers are expanding their customers in the field of biomedicine, aviation, and military industries. Other manufacturers see more opportunities for using special fiber optic cables in sensors and fiber optic gyroscopes. Nevertheless, the use of special optical fibers in communication systems has made more significant progress and promises many new opportunities. It is already clear that in any case of further development, special fiber cables will be used in the equipment of next-generation communication networks.  If you would like to obtain an optical fiber product, you should choose the Optromix company. Optromix is a provider of top quality special fibers and broad spectra optical fiber solutions. The company delivers the best quality special fibers and fiber optic cables, fiber optic bundles, spectroscopy fiber optic probes, probe couplers, and accessories for process spectroscopy to clients. If you have any questions or would like to buy an optical fiber, please contact us at [email protected]

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What are better scrubbers or low-sulfur fuels?

It is a well-known fact that the Marine Environment Protection Committee (MEPC) confirmed that the sulfur content in marine fuel should be at least 0.5% by January 1, 2020. Thus, shipowners have two options: to install air treatment devices on their ships or use fuel with low sulfur content.

So what is better - the installation of scrubber systems or the use of LS fuel (with 0.5% sulfur content)?

Shipowners face a difficult choice that requires several factors to be considered:

· Fuel consumption;

· Age of the vessel;

· Time that the ship spends at sea;

· Navigation area of the vessel;

· How much space is available on the ship;

· How much free power is available for additional equipment on the ship;

· What type of agreement is used with the charter.

Fuel consumption

First of all, it is necessary to pay careful attention to fuel consumption. The owner of a large ship with a large fuel consumption needs to think carefully because he needs to calculate how much the ship uses high sulfur fuel per year, how much does it cost, how much low sulfur fuel will be needed per year, and calculate the difference in money. And then it is recommended to think about whether it will be more profitable to put a scrubber or better to apply LS fuel.

Age of the vessel

Age is also an important factor. Does it make sense to install an expensive system if the ship is going to be sold for scrap soon? Sometimes it is more profitable to build a new vessel with an already installed air treatment system for air pollution control than to maintain the old one according to new requirements.

Navigation area

Air pollution control of exhaust gases will only be performed in ports and the ECA (Emission Control Areas). This means that a large vessel that is located outside these areas for most time can use high sulfur fuel, therefore, it is more profitable to install a scrubber or use a hybrid system.

Installation place of the air treatment system

Each ship is unique. Passenger ships install a scrubber right in the exhaust pipe. Large bulk carriers and tankers can easily install the air treatment system both in the exhaust pipe and make an extension to it. For example, on tankers, most of the equipment is installed on the deck, instead of the engine room.

Where do ships get the power from?

The new scrubber system requires more ship power. Taking into consideration the fact that there are also requirements for the ballast system, most ships will not have enough power, that is why they put an additional generator. The additional generator means more fuel consumption, more supplies, more maintenance, and more responsibilities for the crew.

What about the charter?

The fact is that it takes about a month to install the scrubber. The ship maintenance during one month in the dock is a large minus for the shipowner and an extra headache for the charter.

What if you choose LS fuel?

To begin with, fuel tanks, fuel handling equipment, and pipes must be drained and treated from HS fuel so that it does not mix. It is difficult to imagine how much time the process will take and how long the ship will stay at the pier just for this reason.

Burning distillate fuel can lead to problems with the fuel pumps, which will cause excessive wear and scratches, as well as damage to the old engine.

Moreover, its price will increase because of the increased demand for LS fuel. From this point of view, the vessels with scrubbers will win financially.

And if you choose the scrubber?

The market offers a huge number of wet air scrubbers for air treatment, i.e. they use seawater to clean exhaust gases. These wet scrubbers are divided by the appearance: open and closed-loop, hybrid, built-in, attached type (U-type) scrubber systems.

Open-loop wet air scrubbers are suitable for vessels operating in open seas. The scrubber system takes water and pumps it through the scrubber, treating most of the sulfur from the exhaust, and then discharges the water overboard (mostly without polluting the environment).

The closed-loop scrubbers are ideal for vessels that sail in the ECA areas or frequently enter ports. The operation of this system is similar to an open cycle, only the water does not go overboard, but remains on the ship. Later, the resulting sludge is removed at a suitable port.

The hybrid scrubber system is more expensive, it combines an open and closed type, which is more convenient and economical if you look at the promising future.

Built-in wet scrubbers are installed in the main engine along with the exhaust pipe. They are often used on passenger and container ships.

U-type air treatment systems have become very popular, as they can be attached to the exhaust pipe and do not require its redevelopment. This type is installed faster than the built-in one since the installation is designed and created in advance.

The shipowner will have to go through many stages before the wet air scrubber is installed. It is necessary to choose the type of scrubber, manufacturer, which directly affects the price, delivery, and installation time.

The full installation of the open-loop wet air scrubbers varies between 3-6 million dollars. Delivery of all equipment takes from 7 months to 2 years. The price and delivery time of wet scrubbers increases due to the huge number of orders.

The next problem is to find a manufacturer in a suitable area with the opportunity to store a ship and assemble this system at a favorable price and in the shortest possible time. The shortest time to build this system is 35-40 days.

The availability of manufacturers due to the influx of people who want to install scrubbers for air pollution control is already a problem. Don't forget that the IMO also requires installing ballast tank cleaners. For example, it is known that several Chinese factories reported that their schedule for 2019 is full.

The scrubber system must pass a series of checks and receive a certificate after its installation. The crew must take additional courses. And by the way, do not forget that ship mechanics will have more work that no one will pay for besides.

However, it has been found that scrubbers have less impact on the climate than low-sulfur fuels. 

For instance, an independent environmental research consulting company has published a new study that concludes that the use of wet air scrubbers leads to slightly lower CO2 emissions compared to the use of very low-sulfur fuels on several ships.

Previous studies have shown uncertain results regarding the environmental impact of using scrubbers, especially on what environmental impact matters, how large the impact is, and how it should be evaluated.

The new study provides a comprehensive overview of the climate impact of various options for reducing sulfur emissions. It shows that in many cases the carbon footprint from applying a scrubber is lower than using low-sulfur fuels.

The thing is that wet scrubbing systems remain the most commonly used air treatment devices that allow performing air pollution control. If you search for the best air treatment device to improve air quality, you can buy a high-tech completely new type of wet air scrubber – a Multi-Vortex wet air scrubber produced by Optromix company. Optromix is a fast-growing vendor of wet air scrubbers. The multi-vortex scrubber can remove gas emissions, dust, vapors, and other pollutants from a gas stream.  It is an innovative technology created to save water that makes it more cost-efficient and differs from other types of scrubbers.  If you have any questions or would like to purchase a multi-vortex wet air scrubber, please contact us at [email protected]

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Fiber laser systems act as weapons in military application

Nowadays technological progress has reached a milestone when laser system weapons systems installed on vehicles have become a reality. Vehicle-mounted laser beam weapons are considered to be a low-cost device for improving combat capabilities, applied by both regular and irregular armies involved in almost every conflict in the world. 

Until recently, options for installing weapons on combat vehicles have been limited to machine guns and artillery systems of various types. However, the situation here begins to change with the emergence of fiber laser systems or directed laser beam energy systems that produce enough power to burn small aircraft and ammunition in the air. 

The placement of large power storage units on such systems has always been a serious problem, but recent developments in fiber laser technology have reduced the size of lasers to allow them to be installed even on a large jeep. 

In the 90s, there was a technological revolution in fiber optic communications, which accelerated the development of high-power solid-state laser systems, which found application in industrial processing a decade later – branding, cutting, welding, and melting.

These laser systems are extremely effective at short distances, but it was a matter of time for the industry to find a way to scale this fiber laser technology and develop futuristic weapons that could cut and melt targets at a distance of several hundred or even thousands of meters.

Interest in military applications of fiber lasers increased immediately after the demonstrations of the first quantum generators. The unique properties of laser beam radiation, directivity, monochromaticity, coherence, generation of ultrashort pulses, and high energy concentrations are regarded as very attractive for various weapons systems. 

Laser systems include devices employed to perform measurements and even functional sensors. For military applications, such fiber laser systems are applied for guidance or target designation, rangefinding (determining the distance to the target), control of combat vehicles (proximity sensors), detection, tracking, and visualization of targets (laser beam radars), countering enemy electronic-optical tools. 

Fiber laser weapons always cause a lot of controversies. Some people consider it a weapon of the future, while others categorically deny the likelihood of effective examples of such weapons appearing shortly. People thought about laser beam weapons even before they appeared.

Since the development of the first laser system, a huge number of ways to obtain laser beam radiation have been found. There are solid-state lasers, gas lasers, dye lasers, free-electron lasers, fiber lasers, semiconductor lasers, and other laser systems. 

Also, lasers differ in the method of excitation. For example, in gas laser systems of various designs, the active medium can be excited by optical radiation, electric current discharge, chemical reaction, nuclear pumping, or thermal pumping. The emergence of semiconductor lasers leads to DPSS (diode-pumped solid-state) laser systems.

Various designs allow obtaining different wavelengths of laser beam radiation at the output, from soft x-ray radiation to infrared radiation. Laser systems that emit hard x-rays and gamma-ray lasers are still in development. This allows selecting the fiber laser based on the problem being solved. 

As for military applications, this means, for example, the possibility of choosing a fiber laser system with wavelength radiation that is minimally absorbed by the planet's atmosphere. Since the development of the prototype, the power has continuously increased, the mass and size characteristics and the efficiency of lasers have improved. 

This is very clearly seen in the example of laser modules. Of course, fiber laser modules are not suitable for creating combat lasers, but they are in turn used for pumping efficient solid-state and fiber laser systems. 

An important element of the system is the high-quality laser beam focusing system – the smaller the spot area is on the target, the higher the specific power is that allows damage to be caused. Progress in the development of complex optical systems and the emergence of new high-temperature optical materials allows producing highly efficient focusing systems. 

Another important component that makes it possible to create a laser beam weapon is the development of systems for aiming and holding the beam on the target. Gigawatt power is required to hit targets with an "instant" shot, in a fraction of a second, but the creation of such fiber laser systems and power sources for them on a mobile chassis is a matter of the distant future. 

Accordingly, it is necessary to hold the spot of laser beam radiation on the target for some time (from a few seconds to several tens of seconds) to destroy targets with lasers of hundreds of kilowatts – tens of megawatts. This requires high-precision and high-speed drives that can track the high-quality laser beam on the target, according to the guidance system.

The guidance system must compensate for the distortion introduced by the atmosphere, when shooting at long distances, for which the guidance system can use several laser systems for various purposes, providing accurate guidance of the main "combat" laser beam on the target. 

Because of the lack of power sources for optical pumping, gas-dynamic and chemical laser systems have received priority development in the field of weapons. Despite all the benefits provided by gas-dynamic and chemical lasers, they have significant disadvantages: the need for consumable components, launch inertia (according to some data, it is up to one minute), significant heat generation, large dimensions, and the output of spent components of the active medium. Such lasers can only be placed on large areas.

At the moment, the greatest prospects are for solid-state and fiber laser systems, which only need to provide them with sufficient power to operate. The US Navy is actively working on free-electron fiber laser technology. An important advantage of fiber lasers is their scalability, i.e. the ability to combine several fiber laser modules to get more power.

Modern laser systems adapt to any vehicle that you want to use at the moment and that's why this technology is so impressive, it provides the flexibility of the architecture to fit different vehicles without much refinement. This allows developing a system to support both a combat team and a forward operating base.

The system applies commercial fiber lasers assembled into easily reproducible modules, which makes it very affordable. Using multiple fiber laser modules also reduces the likelihood of minor faults, as well as the cost and volume of maintenance and repair.

There are several characteristics of a directed energy tactical weapon that make it very attractive to modern armed forces, including the low cost of "ammunition" and their speed, accuracy, and ease of use.

First of all, this is a very accurate weapon with potentially very low indirect damage. The speed of laser beam light allows instantly irradiating the target, and, therefore, it is possible to hit highly maneuverable targets, i.e. keeping the laser beam on the target, which sometimes can not cope with kinetic ammunition.

Perhaps the most important benefit of such fiber laser systems is the low cost of one effective "shot". For instance, at this point, you don't want to spend expensive and powerful defensive kinetic weapons on cheap multiple threats. Laser beam weapons are regarded as an addition to kinetic systems. 

The laser system is used against a large number of cheap threats of low intensity, leaving your kinetic force for attacking complex, armored, long-range threats. Such fiber lasers can be employed to protect against flying drones. For example, an American company has introduced a laser system to protect objects from drones. 

A combat laser system shot down five aircraft-type drones during tests in 2017 in New Mexico. The fiber laser system is called ATHENA (Advanced Test High Energy Asset, high energy system for advanced testing). The operating principle is based on a 30-kilowatt fiber laser.

Another application of the laser system was demonstrated using a fiber laser system against missiles.  A message published on the company's website informs that the engineers have managed to solve the issue related to the heating of the high-quality laser beam installation, as well as its compactness, thus, creating an ideal protection system. 

The engineers claim that this is the only company that has an integrated fiber laser weapon system at an acceptable level of power and accuracy, which they have achieved with the ADAM (Area Defense Anti-Munitions) and ATHENA (Advanced Test High Energy Asset) laser systems.

If you are looking for a compact highly-efficient laser system, the Optromix company is ready to manufacture it. Optromix is a manufacturer of laser systems, optical fiber sensors, and optical monitoring systems. We develop and manufacture a broad variety of fiber lasers, high powered fiber lasers, and other types. We offer simple laser products, as well as sophisticated fiber laser systems with unique characteristics, based on the client’s inquiry.  We manufacture laser modules using our technologies based on the advanced research work and patents of the international R&D team. Laser processes are of high quality, high precision, easily-automated manufacturing solutions that provide repeatability and flexibility. If you have any questions or would like to buy a fiber laser system, please contact us at [email protected]

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Fiber optic sensing solutions for extreme conditions

Electrical sensing systems (strain sensors, string-based, potentiometric, etc.) have been the main method of measuring physical and mechanical phenomena for decades. Despite their widespread application, electric sensing systems have a number of disadvantages, such as loss of signal transmission, susceptibility to electromagnetic interference, the need to organize an intrinsically safe electrical circuit (if there is a danger of explosion). 

These inherent limitations make electrical sensors unsuitable or difficult to use for a number of tasks. The application of fiber optic sensing solutions is an excellent way to overcome these problems. The signal in fiber optic sensors is light in the optical fiber used instead of electricity in the copper wire of standard electrical sensors.

Over the past twenty years, a huge number of innovations in optoelectronics and in the field of fiber optic telecommunications have led to a significant reduction in the price of fiber sensor components and to a significant improvement in the quality of fiber optic systems. These improvements allow fiber optic sensors to move from the category of experimental laboratory devices to the category of widely used devices in such areas as monitoring of buildings and structures, etc.

One of the most commonly used fiber optic sensors is considered to be fiber Bragg grating sensors (FBG). The fiber Bragg gratings in these sensors reflect a light signal whose spectral characteristic (wavelength) shifts along with changes in the measured parameter (temperature and/or deformation). During the manufacture of gratings, a region with a periodic change in the refractive index is created inside the optical fiber core, herewith, this region is directly called the FBG.

Optical fibers and fiber sensors are non-conductive, electrically passive, and immune to EM interference. The interrogation using a tunable high-power laser allows measurements to be made over long distances with virtually no signal loss. Additionally, in contrast to the electrical sensing system, each optical fiber channel can interrogate a variety of FBG sensors, which significantly reduces the size and complexity of such a fiber optic system.

Fiber optic sensing solutions are ideal for applications where conventional electrical sensors (strain gauges, strings, thermoresistors, etc.) have proved difficult to use due to extreme conditions (long distances, EM fields, explosion protection, etc.). Since the installation and operation of fiber sensors are similar to conventional electrical sensors, it is easy to switch to fiber optic solutions. Understanding how such fiber optic systems work and the benefits of using them can greatly facilitate various measurement tasks (for example, structural health monitoring).

In short, the main advantages of FBG sensors include:

● high sensitivity and performance;

● relatively large range of measured deformations;

● the best weight and overall dimensions, small size;

● high noise immunity, insensitivity to electromagnetic interference, such as microwave field, spark discharge, magnetic fields, electromagnetic pulses of various nature and any intensity;

● absolute electrical safety due to the absence of electrical circuits between the fiber optic sensor and the recording module;

● full electrical, explosion and fire safety, high chemical resistance of sensor elements.

The conditions of the environment and controlled conditions in which one or more external factors — radiation, temperature, electromagnetic field, aggressiveness, humidity, pressure, and deformation — have the maximum possible constant values are regarded as extreme. 

In such conditions, primary converters of control systems for dangerous technological processes (oil production, transportation, and processing of oil and gas, nuclear power generation, storage of radioactive waste), monitoring and diagnostics systems for complex construction and engineering structures (dams, bridges, mines, etc.), and military and emergency management systems operate.

Currently, fiber optic technologies are widely used in various fields of science and technology. One of the main applications of fiber optics is the creation of portable high-sensitivity sensors. Pressure, strain, vibration, tilt, linear motion, and temperature sensors are widely applied in the industries of structural health monitoring pipelines, heating lines, power cables, mines, etc.

Radiation

Compared to fiber sensors, the lack of power supply at the location of electrical sensing systems does not prevent continuous remote monitoring of dangerous objects, such as nuclear power plants, in an emergency beyond design situations. For instance, the well-known events at the Japanese nuclear power plant "Fukushima-1" in 2011 were characterized by the fact that during the two weeks when the nuclear power plant was completely de-energized, there was no information from electronic sensors, which was extremely important for monitoring the technical condition of the emergency station.

Temperature

Problems of standard sensing systems control of tightness of tanks with liquid hydrogen, which is the fuel of modern rocket engines, has a temperature of -253 °C and very high fluidity, due to the fact that at such temperatures, most materials become very fragile, and the sensitivity of palladium sensors quickly decreases. 

It is problematic to measure the pressure and dryness of superheated steam in gas generators and superheated gas in jet engine nozzles at temperatures up to + 600 °C since piezoelectric sensors quickly degrade at temperatures above + 300 °C. Modern FBG sensors of physical quantities are heat-resistant (up to +2300 °C) and cold-resistant (up to -270 °C). This provides reliable and long-term monitoring of the technical condition of high-temperature and cryogenic objects.

Electromagnetic interference

Measurements of physical quantities using electrical sensing systems in conditions of high-power electromagnetic interference, including guidance on coaxial electrical cables and sensors from lightning discharges, in conditions of monitoring the patient's pulse in a medical nuclear magnetic resonance facility, as well as measurements of high voltages and high currents in electrical engineering, are highly problematic.

Fiber Bragg grating sensors are completely immune to electromagnetic interference and are stable insulators. This makes it possible to measure high voltages up to 800 kV and high currents up to 200 kA with high accuracy (class 02s) by fiber optic sensing technology.

Aggressive environment

Measurements of physical quantities of chemically aggressive media, long — term measurements of deformation of dynamically loaded objects and structures, as well as multi-sensor measurements-with the number of control points in several hundred and thousands, are also problematic for electrical sensing systems since the volume of measuring electrical cables is unacceptably increasing.

Distributed fiber optic sensors are multi-sensors: up to 10 thousand consecutive intra-fiber sensors can be used in one optical fiber (fiber optic cable) to measure physical quantities (temperature, strain, seismoacoustics, pressure, radiation, etc.). Multimode fiber optic cables allow performing remote measurements with high accuracy using borehole video cameras, and temperature fields — using pyrometers and thermal imagers.

Metrological calibration

A serious problem of electrical sensing systems embedded in objects (in the concrete of hydraulic dams and bridges, in the pylons and walls of high-rise buildings, etc.) presents the practical difficulty of their periodic calibration (metrological verification).

Modern fiber sensors have the function of metrological self-monitoring (FMSM) due to the multimodality of the optical signal, which allows for self-calibration of fiber optic sensors in real-time without stopping the controlled processes and without verification standards.

In the last decade, there were implemented many similar applications of modern fiber sensors and systems in extreme environments of nuclear, oil and gas and aerospace industries, shipbuilding, hydraulic engineering, energy, construction, military, and natural emergencies.

Moreover, the durability of FBG sensors in these extreme conditions creates an obvious advantage of their use in the energy, oil and gas, aerospace, construction, and transport industries in comparison with non-optical types of measuring systems.

Thus, the extreme operating conditions of fiber Bragg grating sensors, for example in wells (extreme parameters, flammable, aggressive and abrasive environments) or power plants (ultra-high currents and discharges, voltages and fields, significant ionizing radiation), actually belong to the usual operating conditions of fiber optic sensors.

If you are looking for reliable fiber optic sensing solutions for structural health monitoring, you should choose the Optromix company. Optromix is a fast-growing vendor of fiber Bragg grating (FBG) product line such as fiber Bragg grating 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 [email protected] 

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The full overview of fiber optic bundles applied in medicine

If you would like to obtain an optical fiber product, you should choose the Optromix company. Optromix is a provider of top quality special fibers and broad spectra optical fiber solutions. The company delivers the best quality special fibers and fiber optic cables, fiber optic bundles, spectroscopy fiber optic probes, probe couplers, and accessories for process spectroscopy to clients. If you have any questions or would like to buy an optical fiber, please contact us at [email protected]

A fiber optic bundle is an element of a fiber cable that is a very thin quartz thread with a diameter of 0.1 mm. This optical fiber is used for transmitting electromagnetic radiation. The operating principle of the fiber bundle is based on the use of such processes as reflection, as well as refraction of the wave at the boundary of the shell and the thread itself, which have different properties, which, in turn, depend on the refractive index. 

Due to the fact that the value of laser beam light attenuation in the optical fiber is quite small, fiber optic bundles are often used to transmit an optical signal over long distances. The optical signal is not subject to interference in fiber bundles, and this property is widely applied in the development of fiber optic sensors. Fiber optic bundles make it possible to transmit light like an electric current.

The fiber bundle is considered to be the main element of a fiber optic cable. The optical fiber of which consists of a core, one or more shells, and one or more protective coatings. The core is the central part of the optical fiber, through which the main part of the signal power is transmitted. If the core is employed to transmit electromagnetic energy, then the shell is used for creating better reflection conditions at the core-shell interface, protecting the fiber core from mechanical damage, as well as protecting it from energy radiation to the surrounding space and absorbing unwanted radiation from outside.

Fiber optic bundles are divided into two groups: multimode and single-mode.

The operating principle of the fiber bundle is based on fiber optic technology - a technology for transmitting laser beam light through a fiber optic bundle of optical fibers that are very thin, flexible glass or plastic. A good fiber bundle will transmit the entire spectrum of visible light without loss. These fiber optic cables have a very high-quality optical transmission.

Fiber optic bundles can have different shells, up to metal, but this option is not recommended for use in medicine since it is very difficult to clean. The disadvantage of this fiber bundle is regarded as its fragility. As you use fiber optic bundles, some optical fibers break down. The loss of optical fibers can be seen if one end of the fiber cable is viewed in daylight. The broken fibers are visible as black dots.

To avoid damage to these fibers, it is necessary to take into account the radius of the curvature of the bundle. The fiber may also be damaged if the cooling system of the light source does not work properly. In this case, the optical fibers of the bundle are burned (melted), which dramatically reduces the light intensity. If low-quality fibers or glue are used, the fiber optic bundle may burn out after several months of use.

Fiber bundles are widely used in optical communication systems, in sensors of various types, etc. At the same time, fiber optic bundles have played a huge role in the development of communication, they have a revolutionizing influence on the methods of observation, diagnosis, and treatment in medicine. 

These ultra-thin flexible optical fibers "opened a window into the living tissue of the human body". By inserting fiber optic bundles into natural holes or small incisions and passing them through channels in the human body, doctors can carefully examine the bronchi of the lungs, intestinal folds, heart chambers, and many other internal organs that were previously unavailable for such careful observation. 

By placing fiber optic sensors in the bloodstream, doctors can perform rapid and reliable biochemical analyses directly at the patient's bedside, in the exam room, or in the operating room. All other methods of blood analysis require a certain amount of blood for subsequent laboratory tests. 

By directing laser beam radiation through the fiber bundle, doctors can even perform surgical operations inside the human body, which sometimes avoids the usual surgical procedure involving cutting healthy tissue to have access to the focus of the disease.

By transmitting laser radiation through fiber optic bundles, gastroenterologists, for example, cauterize blood vessels to stop bleeding in the intestines, cardiologists have begun to destroy plaques and blood clots in the peripheral arteries, and neurosurgeons will soon be able to restore nerve fibers in the brain and spinal cord. 

Fiber optic systems can help combine diagnosis and treatment, for example, by combining the means of detecting cancer cells with ways to destroy them without damaging neighboring healthy tissues. Many diagnostic and therapeutic procedures using fiber optic bundles do not require pain relief and can be performed reliably and without risk to health in the doctor's office; therefore, further development of fiber optic technology should reduce the risk and cost of medical care. 

It is possible that the use of fiber optic systems will make medical care more reliable in cases where conventional surgical operations are dangerous or even impossible, for example, in young children or in elderly people.

The application of fiber bundles in medicine began with the use of image transmission systems called fiberscopes in diagnostic practice. The first fiberscope designed to examine the stomach and esophagus was developed in 1957. Since then, such fiber optic systems have been significantly improved, and now they can be used to examine almost all human organs. 

A modern fiberscope consists of two fiber optic bundles: one leads light to the bio tissues, and the other transmits the image to the observer. The fiber bundle is connected to a powerful light source, the light enters the cores of the fiber optic bundle made of high-purity quartz glass. Such an optical fiber is 10,000 times more transparent than window glass and therefore can conduct laser beam light over many kilometers without much loss. 

Individual fiber optic bundles are glued together only at its ends, which provides it with flexibility and at the same time eliminates mixing of individual parts of the transmitted image. The restored image can be viewed through an eyepiece, recorded on videotape, or played back on a display. Since thousands of fiber bundles can be located in a single fiber optic system with a diameter of less than one millimeter, the fiberscope can transmit images with high spatial resolution and almost perfect color reproduction.

The lighting and image-transmitting fiber optic bundles can be easily inserted into a catheter with a diameter of several millimeters resulting in an endoscopic fiber catheter.  Often fiberscopes are considered to be a part of more complex instruments called endoscopes, which have additional auxiliary channels through which the functions of the medical device are expanded. 

For example, it is possible to improve visibility through one of the channels, you can also withdraw fluid from the body or enter water or air to clean the wound from foreign substances or organic residues. Another channel may contain thin wires to rotate the end of the endoscopic fiber catheter. The third channel can have tiny scalpels that can be inserted to cut through the bio tissue and remove polyps, as well as needles for injecting drugs.

Using such fiber optic systems, doctors can examine the internal cavity of the digestive, circulatory, respiratory, and genitourinary systems of a person, take small samples of bio tissues for laboratory tests, and even perform surgical operations. The application of a fiberscope allows doctors to detect polyps in the colon, objects in the lungs, and tumors in the esophagus and then remove them with minimal surgery.

The production of ultra-thin optical fibers developed in recent years has allowed to reduce the diameter of fiberscopes and increase the number of optical fibers in the fiber bundle for observations, which in turn has improved its resolution. The latest endoscopic fiber catheters contain up to 10,000 fiber optic bundles less than one millimeter in diameter. Such a fiber optic system, inserted through an artery on a person's shoulder, can transmit images of heart valves, as well as blockages in the coronary arteries — the vessels that supply the heart with blood.

In addition to obtaining images using fiber optic technology, you can make direct and rapid biochemical and clinical blood tests and solve other problems of human physiology. The main element of such a system is a fiber optic bundle inserted through a catheter into the human body. 

In many cases, a medical examination using fiber optic systems can be more accurate, reliable, and cost-effective than traditional methods that are based on laboratory analyses of fluids taken from the body.

Fiber bundles eliminate analysis delays and reduce the likelihood of errors. In addition, fiber optic sensors do not interact chemically with the body's tissues and do not cause a reaction of the immune system. They are more durable, versatile, and potentially safer than microelectronic devices that are also designed to collect data on the functional activity of the body and are inserted inside the human body. 

Fiber bundles also allow directly determining the oxygen content in the blood. The fiber optic sensor can measure pressure in the arteries, bladder, and urethra. In recent years, the most significant application of fiber optic bundles in medicine is considered to be the transfer of laser radiation energy inside the human body for surgical and therapeutic purposes.

Maintenance of fiber bundles

When maintenance of any fiber optic bundles is performed, the following conditions must be observed:

Handle the fiber bundles carefully.

Avoid twisting them too much.

After the operation has been completed, first disconnect the fiber bundle connector from the endoscopic fiber catheter, and then disconnect it from the light source.

The end of the bundle should be periodically cleaned with a ball of cotton wool moistened with alcohol.

The outer coating of the fiber bundle must be cleaned with a mild cleaning agent or disinfectant.

The distal end of a fiber optic bundle should never be placed near a tissue or near a patient when connected to a light source. The heat generated due to the intensity of the light can cause the patient to burn or ignite the tissue.

The intensity of the light source is so high that there is a chance of damage to the retina if the light falls directly on the eye. Never try to look directly at a working light source, or at the distal end of the fiber optic bundle when it is connected to such a source.

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Fiber laser systems for material processing

Laser technology for material processing, which was appeared about three decades ago, is currently experiencing the peak of its development and popularity. Modern fiber laser technologies are rapidly being introduced into industrial production and advertising business, often replacing traditional methods of material processing.

The focused laser beam of adjustable power turned out to be an ideal "working tool" for the creators of new equipment. The laser system for cutting and marking, welding and surfacing, as a material processing tool, works quickly and does not wear out, it is economical, highly accurate, and its impact is easy to control and manage.

Laser  technologies for material processing have a number of advantages that contribute to the expansion of their application in various industries and services:

wide range of processed materials,

no mechanical impact on the product with minimal thermal,

precision and guaranteed repeatability,

high contrast and durability of the images applied,

high speed and performance, saving on consumables and low power consumption,

possibility of laser beam processing in hard-to-reach places, on flat and curved surfaces,

the ability to integrate the fiber laser into various technological processes, including production lines and robotic systems.

For instance, laser system engraving is effective for personalization of souvenirs and gifts, fiber laser application of personal and greeting inscriptions. Laser beam cutting as a high-precision tool allows producing products with minimal material consumption and without additional processing of the cutting edges. Laser system welding is characterized by high welding speeds and high quality of welds with minimal weld sizes.

Laser hardening

A fiber laser or thermal hardening of metals and alloys by laser beam emission is based on local heating of a surface area under the influence of radiation and subsequent cooling of this surface area at a supercritical rate as a result of heat transfer to the inner layers of the metal.

In contrast to the known processes of thermal hardening by quenching with high-frequency currents, electric heating, melt quenching and other methods, heating during laser beam hardening is not volumetric, but a surface process. At the same time, the heating time and cooling time are insignificant, there is almost no exposure at the heating temperature. 

These conditions provide high rates of heating and cooling of the treated surface areas. Due to these features, the formation of the structure during laser beam heat treatment has its own specific features. The main purpose of fiber laser thermal hardening of steels, cast iron, and non-ferrous alloys is to increase the wear resistance of parts working under friction conditions. 

As a result of laser system hardening, high surface hardness, high dispersion of the structure, a decrease in the coefficient of friction, an increase in the bearing capacity of the surface layers, and other parameters are achieved. Fiber laser hardening provides the lowest wear and friction coefficient, and furnace quenching – the highest. 

Along with this, hardening by the fiber laser system is characterized by very small running time (only two or three cycles), a decrease in the upper values of the number of acoustic emission pulses, and a small interval of change in the number of laser beam pulses. This is due to an increase in the uniformity of the microstructure of the surface area after laser system hardening.

The wear resistance of cast iron and aluminum alloys under sliding friction conditions after continuous laser treatment is noticeably increased. The increased wear resistance of cast iron after laser beam treatment is due not only to the corresponding structural and phase composition but also to improved friction conditions thanks to graphite preserved in the laser zone. It also increases the wear resistance of steels and some other alloys when friction occurs in alkaline and acidic environments.

Laser system cutting

Fiber laser cutting is a laser technology that uses the energy of a laser beam to cut various materials. Laser cutting is usually used on industrial production lines. Technologically, this process is reduced to focusing a high-energy laser stream on the material being cut. The material, in turn, begins to melt, burn, evaporate, or be removed by a stream of auxiliary gas. 

The laser beam cut is characterized by high edge quality and positioning accuracy. Powerful industrial fiber lasers can cut metal sheets and other materials of various shapes with equal ease. Laser system cutting has a number of advantages over other metal-cutting methods. 

Advanced equipment of fiber laser system cutting machine is able to process almost all metals and their alloys. It becomes possible to achieve a minimum area of the cut, while there is almost no deformation of the edges. The purchase of laser system cutting equipment is advisable in cases where it is necessary to perform the following types of work:

● Machine processing of metal without high initial costs and physical contact with metal

● Metal processing without using a large amount of manual labor

● Metal cutting that does not involve further processing of the part

● High-speed metal cutting, which is accompanied by a slight thermal effect on the metal surface

● Cutting of finished products (past painting processes, etc.) without losing the external qualities of the part.

The fiber laser is able to operate in pulse-periodic and continuous modes. The technological capabilities of the laser beam equipment allow performing metal cutting operations that are accompanied by a small amount of waste. Since the laser system cutting machine is characterized by high positioning accuracy, it is possible to significantly reduce the cut tolerance, which leads to the high economic efficiency of cutting. 

The laser beam of high quality makes it possible not only to cut metal with high precision but also to create holes in it with a diameter of 0.2 mm or more. The fiber laser system for cutting is characterized by a high speed of operation, which depends on the power of the laser beam.

Laser cutting equipment makes it possible to process non-rigid parts and parts that are easily subject to deformation. The use of laser technology enables cutting out details of any, even the most complex contour.

Laser engraving

Fiber laser engraving includes the removal of the surface layer of a material (metal, plastic, leather) or coating (paint, electroplating, spraying) under the influence of the laser beam of high quality. Laser system engraving will not be erased and will not fade. It can rightfully be called eternal. 

The laser beam process is controlled by a computer, which allows engraving images from any digital format (after the necessary processing). The laser beam of high quality allows applying high-resolution images. This makes it possible to engrave high-quality microimages and micro texts.

The laser beam modes embedded in the system can vary very widely. This allows adjusting the depth of the burning of the material. For example, there is a deep engraving in metal for maximum clarity and durability or evaporation of the top layer of paint for the product label without affecting the material itself.

In addition to the standard three-dimensional laser system engraving, there is a technology for obtaining color engraving. Colors in fiber laser engraving of metal are achieved due to the appearance of oxide films in the area of laser beam exposure. The laser technology for obtaining them is innovative and unique. The colors are selected separately for each new material.

Laser welding

Fiber laser welding is a welding technology used to attach various parts of metal using a laser system. Due to the high concentration of laser beam energy in the welding process, a small volume of molten metal, the small size of the heating spot, high rates of heating and cooling of the weld metal and the near-weld zone are provided.

The process is often used to perform large volumes of production, such as in the automotive industry. Depending on the purpose, continuous or pulsed fiber laser operation can be used. A laser beam with a pulse time of the order of milliseconds is used for welding very thin workpieces. A continuous laser system is used for deep welding.

Fiber laser welding is a universal welding method that can be used to weld carbon steel, stainless steel, aluminum, and titanium. A high cooling rate can lead to thermal damage when welding carbon steels. The welding quality is high, similar to electron beam welding. The welding speed is proportional to the applied power, and also depends on the type and thickness of the workpieces. 

The high power potential of fiber laser systems makes them particularly suitable for large production volumes. This type of welding is particularly dominant in the automated industry. Some of the advantages of fiber laser welding compared to conventional include: air route can be used to transmit laser beam, that is, there is no need to vacuum, it is easy to synchronize manipulators, there is no x-ray radiation, it provides the best quality of welds.

One of the methods of laser system welding is hybrid laser beam welding. This is a combination of laser and arc welding (gas metal arc welding). The electric arc melts the wire, ensuring a constant arc length, while the wire is put automatically by the wire feeder. Protective gases (argon, helium, carbon dioxide, and their mixtures) are used to protect against the atmosphere, which is appeared from the welding head together with the electrode wire.

If you are looking for a compact highly-efficient laser system, the Optromix company is ready to manufacture it. Optromix is a manufacturer of laser systems, optical fiber sensors, and optical monitoring systems. We develop and manufacture a broad variety of fiber lasers, high powered fiber lasers, and other types. We offer simple laser products, as well as sophisticated fiber laser systems with unique characteristics, based on the client’s inquiry. 

Moreover, our fiber lasers are exceptionally light and compact and can be embedded in other devices or used in mobile applications. Our company offers single-mode Erbium lasers and Ytterbium lasers as well as single-frequency fiber lasers (similar to DFB lasers), wavelength-tunable fiber laser systems, and unique DUV fiber laser system.  We manufacture laser modules using our technologies based on the advanced research work and patents of the international R&D team. Laser processes are of high quality, high precision, easily-automated manufacturing solutions that provide repeatability and flexibility. If you have any questions or would like to buy a fiber laser system, please contact us at [email protected]

[optromix]

The need for air pollution control has significantly increased

Basic facts

● Air pollution is one of the main health risks associated with the environment.

● The lower the levels of air pollution are, the better the cardiovascular and respiratory health of the population are in both the long and short term.

● In 2016, 91% of the world's population lived in areas where pollution levels exceeded the values set in the WHO's air quality recommendations.

● In 2012, according to estimations, 4.2 million premature deaths occurred worldwide due to air pollution in urban and rural areas.

● About 91% of these premature deaths occurred in low-and middle-income countries with the highest number of deaths in the regions of South-East Asia and the Western Pacific.

● Policies and investments in support of cleaner transport, energy-efficient housing, energy generation, and industry, as well as improved urban waste management, contribute to reducing the main sources of urban air pollution.

● In addition to air pollution, indoor smoke poses a serious health risk to the estimated 3 billion people who cook and heat their homes using biomass and coal fuels.

The Nature Communications organization has published a study according to which a sharp reduction in carbon emissions into the atmosphere can become cost-effective in the short term.

According to the latest data, most people die because of polluted air in India and China. That is why these countries should first of all fight against particulates into the atmosphere, but the governments of these countries do not pay enough attention to the problem.

Experts claim that the reduction of greenhouse gas emissions will decrease mortality and the percentage of serious diseases in places with polluted air in our generation, and improvement of the resident health in problem regions will save money allocated annually for health care.

This point is crucial, but it is not fully taken into account in the global economic analysis of how much the world community should invest in the fight against climate change.

At the same time, the amount of benefit directly depends on the policy of controlling environmental pollution and can reach several trillion dollars per year.

Authors of the study note that usually it is customary to talk about the contribution of our descendants and our planet when discussing the problems of air pollution control but, as evidenced by the latest work in this area, the benefit (including economic) can be obtained in the coming years by eliminating harmful particulate pollutants.

To be more precise, air pollution is considered to be the main cause of the global environmental threat. The international labor organization defines air pollution as the presence in the air of particulates that are harmful to health or dangerous for other reasons, regardless of their physical form. The burning of fossil fuels, agricultural activities, and mining are just some of the causes of air pollution. Carbon dioxide, sulfur dioxide, nitrogen oxides, and dust are regarded as the most popular and most polluting the atmosphere.

Any particulates pollute the air: gaseous, solid and liquid if they are contained in it in quantities exceeding their average content. Air pollution is divided into dust and gas. The World Health Organization defines polluted air as if its chemical composition can negatively affect the health of people, plants, and animals, as well as other elements of the environment (water, soil). Air pollution is the most dangerous of all types of pollution because it is mobile and can pollute almost all components of the environment over large areas.

Main sources of air pollution include:

● industrialization and a growing population,

● energy sector,

● transport industry,

● natural source.

The growing demand for energy has made the burning of hydrocarbons the main source of anthropogenic air pollution.

The most dangerous particulate pollutants are:

● sulfur dioxide (SO2),

● nitrogen oxides (NxOy),

● coal dust (X2),

● volatile organic compounds (benzopyrene),

● carbon monoxide (CO),

● carbon dioxide (CO2),

● tropospheric ozone (O3),

● lead (Pb),

● suspended dust.

Anthropogenic sources of air pollution include:

● low-altitude emissions,

● chemical conversion of fuel,

● extraction and transportation of raw materials,

● chemical industry,

● processing industry,

● metallurgical industry,

● cement production,

● landfills for raw materials and waste,

● motorization.

Natural sources of air pollution are the following:

● eruption,

● chemical weathering of rocks,

● forest and steppe fires,

● lightning,

● space dust,

● biological process.

Particulate pollutants are absorbed by people mainly during breathing. They contribute to the development of respiratory diseases, allergies, and reproductive disorders. Air pollution causes corrosion of metals and building materials in everyday life. It also negatively affects the plant world, disrupting the processes of photosynthesis, transpiration, and respiration. 

Particulates also worsen the condition of water and soil. Globally, air pollution has an impact on climate change. Air pollution also increases the acidity of drinking water. This causes an increase in the content of lead, copper, zinc, aluminum, and even cadmium in the water entering our apartments. Water with high acidity destroys water supply systems, washing out various toxic substances.

According to the World Health Organization (WHO), financial losses because of poor air pollution control in Europe amount to about 1.6 trillion US dollars. This is the result of about 600,000 premature deaths (about $ 1.4 trillion) and diseases (about $ 200 billion).

The effects of insufficient air pollution control include:

● Acid rain - precipitation with a low pH level. According to some information, acid rain increases infant mortality and the risk of developing lung diseases, as well as causes the oxidation of rivers and lakes, destruction of flora and fauna, soil degradation, destruction of monuments and architecture.

● Smog – polluted air containing a high concentration of dust and toxic gases, the source of which is mainly cars and industrial enterprises.

● Unpleasant odors – the result of the presence of particulate pollutants in the air that irritate the olfactory receptors. The effect of unpleasant odors on human health is usually psychosomatic.

● Ozone holes - a decrease in ozone content. The ozone layer is a natural filter that protects living organisms from harmful UV radiation. 

● The greenhouse effect is a phenomenon that occurs in the atmosphere of the planet, causing an increase in the temperature of the planet, including the Earth.

Air pollution caused by cars is responsible for about 1/4 of the deaths in huge cities. In addition to dust, vehicles are a source of nitrogen dioxide emissions, a substance that is at the center of the scandal was the German automaker Volkswagen, which falsified the results of environmental tests of its cars.

As the world around us becomes more polluted and overpopulated, engines continue to emit particulate pollutants into the atmosphere, and half of the entire population does not have access to clean fuels or technologies (such as stoves and lamps), the levels of air pollution we breathe become more dangerous — currently, 9 out of every 10 people breathe polluted air, resulting in 7 million deaths each year.

Poor air pollution control has severe health consequences — one-third of deaths from stroke, lung cancer, and heart disease are caused by air pollution. This is equivalent to exposure to tobacco smoke and is significantly more severe than, for example, the consequences of consuming excessive amounts of salt.

Air pollution is difficult to avoid no matter how rich the area you live in. Microscopic particulates can pass through our body's defenses, penetrating deep into the respiratory and circulatory systems and destroying the lungs, heart, and brain. 

The absence of visible smog does not mean that there is healthy air around. All over the world, both cities and villages are exposed to toxic levels of particulate pollutants that exceed the annual average recommended in the WHO air quality guidelines.

Herewith, according to the opinion of health specialists, people who live and work in high air pollution are more attackable to the COVID-19 - today the most thrilling disease, causing panic all over the world. There is an opinion that air pollution control systems such as scrubbers are considered to be one of the best ways to prevent people from lung infections resulting in the reduction of infectious diseases like coronavirus. 

If you would like to make your contribution to improving air quality in order to provide air pollution control, you should choose a new type of wet scrubbers that is Multi-Vortex scrubber. Multi-Vortex wet air scrubber could apply water contaminated with dust, sand, and even small rocks to capture particulate pollutants, different types of dust, and some gases from the air.  This type of scrubber is an ideal solution for ore and coal mining. Thus, it can be used in different mining, combustion, and chemical processes to capture gases. Also, in some cases, the unique Multi-Vortex scrubber design allows utilizing cheaper reagents to capture the pollutant gas with more efficiency than a standard wet scrubber. If you would like to buy Multi-Vortex wet air scrubber or have some questions, please contact us at [email protected]

[optromix]

Distributed temperature sensors promote warning systems

If you are interested in DTS systems and want to learn more, please contact us at [email protected]

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.

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.

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.

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.

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.

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.

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.

The fiber optic sensing system consists of distributed temperature sensors designed to measure temperature along the borehole, and 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.

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. 

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.

[optromix]

Optical fibers: past and present

In 1966, Charles Kao Kuen, a scientist from China, presented the results of his research to the world. The main message of his development was that fiber optic communication can be organized using optical fibers. In his research, Kao introduced the unique design features of optical fiber and its materials to the world. Researches of the scientist can rightfully be considered the basis of fiber optic telecommunications today.

The very first mention of the term “optical fiber” was first used in 1956 by NS Kapany from the USA. Today, fiber optic communication technologies have so firmly penetrated our lives that we no longer see anything surprising in them and perceive their presence as well as the presence of a water supply system in an apartment building. During the development of fiber optics, many interesting studies and experiments have been carried out.

Active talks about optical fiber LEDs began in the fifties of the last century. Then they began to make them from various kinds of transparent materials. However,  the transparency of those materials was not enough for good light conductivity. In 1966, a group of scientists led by Charles Kuen Kao concluded that quartz glass would be the most suitable material for fiber optic communications. 

Even then, Kao believed that with the help of fiber optics it would be possible to transmit information and soon this type of communication would replace the signal transmission via copper wires. Three years later, Kao received a fiber with an attenuation coefficient of 4 dB/km. This result was the first instance of ultra-transparent glass. 

A year later, Corning Incorporated produced optical fibers with a stepped refractive index profile and reached an attenuation coefficient of 20 dB/km at a wavelength of 633 nm. For the first time, a quartz optical fiber passed a light beam at a distance of up to 2 kilometers. Quantum data transfer is currently developing similarly as an experiment and commercial use over short distances. 

Today, optical fiber is used in many industries besides Telecom. It includes X-ray machines, where it provides galvanic isolation between a high voltage source and low-voltage control equipment. In this way, staff and patients receive isolation from the high-voltage part of the equipment. Optical fiber is used in distribution devices of electric substations as a sensor of the protection system.

Optical fibers are widely used in various types of measuring systems, where it is impossible to use traditional electrical devices. For example, their applications include temperature measurement systems in jet engines of an airplane, tomographic medical devices for the study of internal organs, including the brain, etc. Optical fiber sensors can measure vibration frequency, rotation, displacement, speed and acceleration, twisting, and other parameters.

Today, optical fiber-based gyroscopes are used, which operate based on the Sagnac effect. This gyroscope has no moving parts, which makes it very reliable. Even though modern navigation systems use a huge number of different sensors that determine the position of the object, the most independent system can be created only based on fiber optic gyroscopes.

Fiber optics are widely used in security alarm systems. Such a security system is arranged as follows: when an intruder enters the territory, the conditions for passing light through the light guide change, and an alarm is triggered. Optical fiber is actively used for decorative purposes, as a holiday decoration, in art and advertising.

New types of optical fibers are constantly being developed. For example, photonic-crystal light guides. The propagation of light in them is based on slightly different principles. These fiber optics can be used as a liquid, chemical, and gas sensor. Also, it can be used for transporting high-power radiation for industrial or medical purposes.

Fiber lasers with a continuous output power of several tens of kilowatts are no longer new. Weapons based on 5.5 kW lasers with 6 optical fiber were tested in the U.S. Navy in 2014. Fiber lasers cut metal and concrete. For example, the IPG Photonics metal cutting machine has a capacity of 100 kW.

The development of an optical fiber that could be used to transmit laser energy with the power of several kilowatts continues. In theory, the transmission of emission with a power of 10 kW over a 250 m long fiber with a core diameter of 150 microns is considered to be possible. It is also worth noting that multi-core optical fibers are being actively developed today. Their use will significantly increase the total bandwidth of the fiber optic network.

Fiber systems are in its fifties, but the fiber technology is not going to retire. Innovations in the field of optical fiber appear regularly and Telecom is not the only industry interested in the development of fiber optic technology. Optical fibers are used, for example, as sensors for measuring temperature, pressure, and mechanical stresses. 

Besides, fiber optic systems are often used as distributed spectroscopic and acoustic detectors for probing oil wells. In extreme conditions, cracks appear on the surface of the fiber. At high temperatures and pressures, hydrogen and moisture quickly penetrate the material, and its transparency and, as a result, other characteristics deteriorate.

Physicists have found out why this happens. Using Raman scattering, scientists have proved that allotropic carbon compounds (carbon nanotubes, fullerenes, graphenes) are present in the protective layer of optical fibers. Such nanostructures can play the role of additional channels for the penetration of hydrogen and moisture to the core of optical fibers, impairing transparency for light signals. The results of the study will help optimize the technological processes for creating optical fibers with a protective carbon layer so that they can be used in the exploration of oil wells.

Innovations in fiber optics

Standard optical fiber with a "step" change in the refractive index directs the light due to the effect of total internal reflection. This effect is easy to observe, if you look from below at a glass of water at a slight angle, the surface of the water will appear mirrored. Similarly, light beams in a fiber system are reflected from the walls and can propagate without loss over large distances. 

At the same time, the rather low values of the angle of internal reflection in the optical fiber and the wave nature of the light establish the conditions that the propagation of light is possible only at certain angles. In other words, the fiber supports the propagation of several discrete "modes". Optical fiber, which allows the propagation of only one mode, is called single-mode - these are the fibers that are most suitable for use in telecommunications.

What are the disadvantages of such a standard optical fiber with a stepwise change in the refractive index? In fact, none. Such a fiber optic system copes pretty well with all the applications for which it was originally developed. The problem is that modern industry needs something more.

It is not enough to perform only one job  - well-flexibility (literally and figuratively), the ability to integrate with other devices and devices is valued as highly as the classic reliability of conventional fiber optics. And such a fiber loses wherever some unusual properties are required, such as the ability to transmit high power, compatibility with various sensors and fiber optic lasers on rare-earth metals, possess high nonlinearity, birefringence, or dispersion. 

In other words, conventional optical fiber is only perfect for simple applications in telecommunications. A huge number of new applications appeared with the advent of such objects as microstructured fiber, an optical fiber with a photonic crystal, fiber lasers, mode synchronizers on carbon nanotubes, nanoplasma structures.

Microstructured fiber optics

Unlike optical fiber with a stepwise change in the refractive index, which is usually made of two or more types of glass (for example, germanium-doped glass has a higher refractive index and is used to produce the central part of the fiber), a microstructured fiber optics can be made entirely of one type of glass. The outer layer with a low refractive index is replaced here with a large number of cylindrical cavities filled with a specific gas or simply air.

The technique of producing such optical fibers was introduced in 1991 and has been constantly developing since then. The technology is based on a simple idea: glass tubes of relatively large size are stacked together in the desired structure, which is subsequently drawn under heating into an optical fiber with a specific arrangement of air cavities, the geometry of which is determined by the initial arrangement of the tubes. Depending on how the full internal reflection mechanism is implemented, these fibers can be divided into two types: cavity fibers and fibers on photonic crystals.

Cavity optical fibers

In the cavity fibers, the glass central part is surrounded by a set of cylindrical air cavities, which reduces the effective refractive index and greatly modifies the effect of total internal reflection. Since the size of the air cavities and the distance between them are comparable with the wavelength of light (hundreds of nanometers), the effective refractive index will also vary with the wavelength of transmitted light. The result of this is the ability of such an optical fiber to carry only one mode, regardless of the wavelength. Such fibers are commonly used to transmit high light powers and have low nonlinearity.

Optical fiber with a photonic crystal

Compared to all other fibers in the optical fiber with a photonic crystal does not use the total internal reflection. The collecting of light in the center of such a fiber system occurs due to the phenomenon of interference on a periodic structure with a size of the order of the wavelength created by the lattice of cylindrical cavities - a photonic crystal. 

Although the fact that the physics of photonic crystals, and especially their production, is still developing, we often face related phenomena in everyday life. These phenomena give a bright color to the wings of some butterflies and holograms on our credit cards. And in that and other cases, certain colors stand out from the white light due to interference. The advantage of such fiber optics is the low dispersion since light now propagates in an almost dispersion-free medium-air.

Frequency converters on cavity lasers

The ability to get rid of any restrictions on the environment in which light propagates inside the fiber opens up very interesting prospects and applications. Thus, light propagating inside the central part of the optical fiber filled with a certain gas will collect information about this gas (for example, due to Raman scattering).

Raman scattering can also be used for frequency converters. The passing light excites vibrational modes in the gas molecules that fill the fiber. The reemission of light at a lower frequency, as a rule, is a rather weak effect, however, in the case of an optical fiber, it is enhanced due to the enormous length at which the interaction takes place (along the entire length of the fiber), as well as due to local amplification of the electric field.

Fiber optic lasers

Fiber optic laser technology has developed rapidly over the past few decades. In such lasers, the active medium is located inside the optical fiber itself. The characteristics of fiber lasers are improving every year and have almost reached the characteristics of conventional lasers in terms of power, pulse duration, and generation bandwidth. At the same time, the combination of fiber lasers with microstructured fiber opens up new prospects for such devices. Such structures have low bending losses and increased selectivity between modes.

Mod synchronizers on carbon nanotubes

Currently, fiber lasers are used in a variety of fields, from telecommunications to laser surgery. One of the main advantages of such lasers is the ability to generate ultra-short pulses of light in the picosecond and sub-picosecond ranges. For such applications, fiber optic lasers use passive mod synchronizers, a device whose optical transparency varies with the intensity of the transmitted light. Recently, mode synchronizers on carbon nanotubes are more often used.

Chemical and biological sensors based on fiber optic technology

The development of nanotechnology and in particular nanoplasmonics, together with fiber optics, leads to the emergence of new devices and sensors. Nanoplasmonic structures allow efficiently converting plasmon resonances of various chemical compounds adsorbed on the surface of an optical fiber into optical signals propagating through a fiber. Multiple amplification of the local electric field makes these sensors sensitive to single molecules.

Recently, fiber optics is undergoing a rebirth through integration with various nanostructures. This symbiosis leads to completely new, sometimes unexpected, applications. There is no doubt that soon we will witness the widespread penetration of devices based on optical fibers in various areas of the industry from telecommunications to medicine. If you would like to obtain an optical fiber product, you should choose the Optromix company. Optromix is a provider of top quality special fibers and broad spectra optical fiber solutions. The company delivers the best quality special fibers and fiber cables, fiber optic bundles, spectroscopy fiber optic probes, probe couplers and accessories for process spectroscopy to clients. If you have any questions or would like to buy an optical fiber, please contact us at [email protected]

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How air pollution destroys our health

As the world around us becomes more polluted and overpopulated, factories continue to emit air pollutants into the atmosphere and half of the people does not have access to clean fuels or technologies, the levels of air pollution we breathe are becoming more dangerous — currently, 9 out of every 10 people breathe particulate pollutants, which lead to 7 million deaths each year.

Air pollution has severe health consequences - one-third of deaths from stroke, lung cancer, and heart disease are caused by the absence of air pollution control and insufficient air treatment. This is equivalent to exposure to tobacco smoke and much more serious than, for instance, the consequences of consuming excessive amounts of salt.

Air pollution is difficult to avoid no matter how rich the area you live in. Microscopic particulate pollutants can pass through the protective mechanisms of our body, penetrating deep into the respiratory and circulatory system and destroying the lungs, heart, and brain.

The absence of visible smog does not mean that there is healthy air around. All around the world, both cities and villages are exposed to toxic air pollutants that exceed the annual average recommended in the WHO air quality guidelines (the World Health Organization).

The true cost of climate change can be seen in our hospitals and felt by our lungs. The influence of dirty energy sources is so great that the transition to cleaner and more sustainable options for energy, transport and food systems will eventually pay off. When health concerns are taken into account, reducing the effects of climate change promises opportunities, not costs.

"Breathe Life", a global campaign for clean air led by the WHO, the Climate and Clean Air Coalition, and the United Nations Environment Program, calls on communities to reduce the impact of polluted air in cities, regions, and countries, providing strict air pollution control, herewith, it currently reaches about 97 million people.

The WHO, the UN environment program and the "Breathe life" campaign of the Climate and clean air coalition have developed an online tool for measuring particulate pollutant levels to help people better understand how polluted the air is where they live. 

The WHO and its partners have repeatedly held conferences on air pollution and human health in order to bring all of humanity together to meet key commitments to solve the problem. The conference attendants draw attention to this growing public health issue and provide information and tools for taking action on health risks associated with air pollution.

The Conference focuses on air treatment activities. There are available strategies for reducing emissions from energy generation, vehicle use, waste management, housing, and industrial activities. These air pollution control activities often provide other benefits, such as limiting traffic and reducing noise that contribute to improved health and well-being.

Better air quality provides benefits for all of us and everywhere. The conference calls for urgent action and agreement on a goal to reduce deaths caused by air pollution.

There are two types of pollution — outdoor air pollution and indoor pollution, which is associated with burning fuels (such as coal, firewood, or kerosene) over an open fire or in stoves in poorly ventilated areas. Both types of air pollution can aggravate each other, as air moves from rooms to the outside and vice versa.

Indoor air pollution kills 4 million people every year, mostly in Africa and Asia, where polluting fuels and technologies are used daily in homes for cooking, heating, and lighting. Women and children who spend more time indoors are most affected.

The main particulate pollutants are fine particles, i.e. a mixture of solid particles and small drops produced mainly in fuel combustion and traffic; nitrogen dioxide arising from traffic and use of gas stoves indoors; sulfur dioxide resulting from the burning of fossil fuels, and ozone at the earth's surface, formed by the reaction of sunlight with air pollutants emitted by motor vehicles. The greatest impact on people is caused by small particulate matters (often referred to as PM and used as a unit of measurement for air pollution).

Particulates with a diameter of 10 microns or less (≤ PM10) can penetrate and settle deep in the lungs, but even more dangerous to health are particles with a diameter of 2.5 microns or less (≤ PM2.5). These are the smallest particulates — 60 of these particles are equal to the thickness of a human hair.

PM2.5 can enter the lungs and circulatory system. They can increase the risk of heart and respiratory diseases, as well as lung cancer.

Polluted air has a devastating effect on children's health. Worldwide up to 14% of children aged 5-18 years suffer from asthma caused, among other things, by air pollution. Every year 543.000 children under the age of 5 die from respiratory diseases related to air pollution. Air pollution is also linked to childhood cancer. The influence of polluted air on pregnant women can lead to fetal brain development. Air pollution is also associated with cognitive impairment in both children and adults.

Ozone is one of the main causes of asthma (or its aggravation), and nitrogen dioxide and sulfur dioxide can also lead to asthma, bronchial symptoms, pneumonia, and reduced lung function. 

In addition to affecting our health, air pollutants cause long-term environmental damage, leading to climate change, which is also a significant threat to health and well-being.

The WHO and its partners, such as the United Nations Environment Program, are developing air treatment options for supporting countries. For example, the WHO is developing a set of methodologies (a set of methodologies for ensuring clean energy sources in households) to help countries implement the WHO's recommendations on household fuel combustion and develop strategies for increasing the use of clean energy sources at home.

The UN intergovernmental group of experts on climate change has warned that to limit the rate of global warming at 1.5°C, it is necessary to stop generating electricity by burning coal by 2050. Otherwise, we may see a major climate crisis in 20 years.

So how can we achieve air pollution control? For example, at present, the requirements of legislation and industry regulations on environmental protection have significantly increased. Each company that releases various particulate pollutants into the air pays for ambient air pollution if they do not exceed the established standards, in case of exceeding the standards, are subject to penalties up to the suspension of production.

Besides, it is possible to perform the air treatment of polluted air in industries. Gas air treatment devices, such as scrubbers are used for cleaning industrial gaseous waste.

A scrubber is an industrial unit used for air treatment of waste polluted air from various particulates. The scrubber is considered to be the most effective device for removing solid particles of any dispersed composition from gases. In addition to capturing dust, it can perform heat exchange and absorption processes.

A wet scrubber is a device designed for air treatment of gas from various impurities by washing the gas medium with a liquid (usually water).

The scrubber applications include:

●     Engineering;

●     Chemical industry;

●     Ferrous and non-ferrous metallurgy;

●     Oil production and petrochemical industry;

●     Coal industry;

●     Powerhouses;

●     Other areas of industry where there is a need to clean the gas from particulate pollutants.

The scrubber operating principle is based on the wet air treatment technique — the gas in the working chamber is mixed with water or other technical liquid, as a result, water droplets surround dust particulates or other contamination, after which the treated gas goes into the atmosphere, and the wastewater is drained from the working chamber. The wet air scrubber can treat the gas up to 99% due to this principle of operation.

Scrubber systems differ in the principle of operation - the size and performance of scrubbers depend on this.

Main types of scrubbers:

Centrifugal wet air scrubber;

Nozzle scrubber;

Hollow scrubber;

Venturi scrubber;

Packed bed scrubber (which, in its turn, is divided according to the principle of operation into foam and bubble).

Advantages of using scrubber systems for air treatment:

● The wet air scrubber allows you to quickly and effectively treat the environment from various particulates. The system demonstrates an uninterrupted operation for a long time.

●    The design meets safety standards. The equipment can operate even at pressures above 0.07 MPa.

●    The scrubber is multi-functional since it can be used not only for dry but also for wet air treatment. Small and large pollution, smoke, fumes, and dust are eliminated almost instantly.

●    The wet scrubber reduces the flue gas temperature and steam condensation, which is especially important for large petrochemical plants.

●    The design humidifies the air. Evaporation occurs smoothly, so temperature and pressure differences are not obvious.

● The wet air scrubber is a cost-effective device, as in the process of operation in the equipment are disposed of outgoing gases.

If you would like to make your contribution to improving air quality in order to provide air pollution control, you should choose a new type of wet scrubbers that is Multi-Vortex scrubber. Multi-Vortex wet air scrubber could apply water contaminated with dust, sand, and even small rocks to capture particulate pollutants, different types of dust and some gases from the air.  This type of scrubber is an ideal solution for ore and coal mining. Thus, it can be used in different mining, combustion and chemical processes to capture gases. Also, in some cases, the unique Multi-Vortex scrubber design allows utilizing cheaper reagents to capture the pollutant gas with more efficiency than a standard wet scrubber. If you would like to buy Multi-Vortex wet air scrubber or have some questions, please contact us at [email protected]

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Medical application of fiber laser systems

More than 40 years have passed since the development of the first laser system, but this was enough to make quantum electronics one of the leading areas of science and technology. Numerous improvements of lasers and their application make it possible to obtain fundamentally new results in information systems and communications, in biology and medicine, in space and other scientific researches.

Laser beam emission is characterized by monochromaticity, sharp focus, due to which it is possible to concentrate laser beam energy and power at considerable distances, the ability to vary the modes of radiation from continuous to pulsed with different pulse durations, and finally, coherence and polarization. A unique combination of these properties allows realizing various interaction mechanisms - both thermal (plasma formation, ablation, evaporation, melting, heating), and non-thermal (spectral resonance) effects on matter, which affect complex atomic and molecular systems.

It is not surprising that the idea of using laser beam radiation in medicine appears one of the first. Over the past years, fiber laser devices and techniques have been used in almost all sections of medicine. Fiber lasers are especially successfully used in surgery, therapy and in the diagnosis of diseases. At the same time, it was discovered that each type of laser system operation, each laser-medical technique requires a specific combination of basic parameters of laser beam radiation and knowledge of the mechanisms of its interaction with various tissues.

Today there are three main areas of fiber laser application in medicine:

- New methods of non-invasive diagnostics: optical coherence tomography is considered to be a promising method for the diagnosis of ophthalmic and cancer diseases, laser spectral analysis of biomarker molecules in exhaled air for diseases of the gastrointestinal tract. 

It is these diagnostics that use such unique properties of laser beam radiation as high coherence and polarization, which distinguishes it from ordinary, even monochromatic, light.

- The therapy by fiber laser systems is widely used: irradiation with low-intensity laser systems of poorly healing wounds or human blood; in combination with photosensitizers, low-energy fiber lasers are used to selectively destroy cancer cells, atherosclerotic plaques, and treat macular degeneration (photodynamic therapy).

- Finally, powerful (high-energy) laser systems, which are used as a surgical tool in ophthalmology, otorhinolaryngology, urology, cosmetology. The surgery uses high-intensity laser systems that cause irreversible changes in tissues: welding, evaporation, ablation (removal and cutting).

The therapy by fiber laser systems is another area that has become most widespread in the whole world - irradiation with low-energy lasers of blood and poorly healing wounds.

For external use, laser system treatment occurs by exposure to certain areas and points of the body. The light penetrates through the tissues to a greater depth and stimulates the metabolism in the affected tissues, activates the healing and regeneration of wounds, there is a general stimulation of the body as a whole.

During intravenous fiber laser system therapy, the laser beam influences the blood through a thin light guide that is inserted into a vein. The intravascular effect of low-intensity radiation allows you to affect the entire mass of blood. This leads to stimulation of hematopoiesis, strengthening immunity, increasing the transport function of blood, and also helps to increase metabolism. Significantly positive effects in laser system therapy of angina pectoris, myocardial infarction, and other pathologies were obtained with the introduction of an optical fiber through which laser beam radiation was introduced into the patient's elbow vein.

Fiber laser radiation differs from ordinary, even monochromatic light by its coherence and polarization. There is a misconception that these special properties are responsible for the observed clinical and photobiological effects. As laser beam penetrates deeper into the biological tissue (skin, organ, blood), coherence and polarization persist only to a depth of 200-300 microns, and then these properties disappear and incoherent and non-polarized, monochromatic radiation spreads. Consequently, the beneficial effects observed during laser system therapy of various diseases are caused not by some special properties of fiber laser exposure, but they are similar to the action of ordinary unpolarized and incoherent light with an appropriate radiation wavelength.

Photons emitted by electrons of excited biomolecules form secondary radiation that propagates (scatters) in all directions and excites other biological tissue molecules, increasing the depth of effective exposure. Due to the diversity of biomolecules in the body, secondary radiation is broadband, incoherent and non-polarized.

Another factor that increases the depth of effective exposure is the transfer of excited molecules by blood and lymph throughout the body. It can be assumed that at depths exceeding 3 cm, the main biological effect is exerted not by the primary, laser beam radiation, but rather by the secondary scattered broadband incoherent and non-polarized radiation.

It is also very difficult to determine in practice the dose of absorbed laser beam radiation, since the proportion of reflected and absorbed radiation depends on many reasons, so some researchers believe that fiber laser system therapy is an art like all medicine.

Today, two applications of fiber laser selective excitation of material vibrational levels in the mid-IR region of the spectrum are distinguished: fiber laser surgery of soft and hard tissues and laser system evaporation of polymers for thin-film spraying. These fiber laser system applications are based on the ability of mid-IR lasers to cause thermal or thermomechanical changes in the materials being processed, which can be classified as phase changes rather than laser beam chemistry. Fiber lasers have great potential for creating precision surgical instruments, due to their ability to focus laser beam radiation into a small spot on the length. A larger penetration depth increases the number of damaged cells, while a shorter depth results in less material removal per pulse.

The goal of laser beam ablation is to remove a specific part of the tissue, leaving the surrounding tissue biologically alive. Surgical requirements, however, are often the opposite: high ablation rates are required in dentistry, while they should be minimal in refractive ophthalmology; cutting vascular tissues (brain surgery) requires some amount of surface coagulation (“thermal damage”) in order to achieve hemostasis (stop bleeding), while for non-vascular tissue (cosmetology) wound healing is better when there is no thermal damage.

Laser systems are finding new applications in PDT, a new cancer treatment method. Unsuccessful attempts to control the development of cancer remain a major problem. The main goal for patients with an incurable disease is to delay the development of the tumor. If the tumor is not large, the fiber laser system thermal ablation may become the treatment.

Photodynamic therapy (PDT) by laser systems is another minimally invasive strategy for the removal of tumors. The idea behind PDT is to use the toxicity of porphyrin to destroy tumors. Up to the present moment, it has mainly been used to treat superficial, malignant or pre-malignant lesions of the mucous membrane, carcinoma of the bladder, tumor of the esophagus or bronchus, a tumor on the head or neck, accessible through the endoscope. In combination with special catheters and the development of new photosensitizers, PDT by fiber laser systems can be effective for patients with solid tumors and especially with liver metastases. 

If you are looking for a compact highly-efficient laser system, the Optromix company is ready to manufacture it. Optromix is a manufacturer of laser systems, optical fiber sensors, and optical monitoring systems. We develop and manufacture a broad variety of fiber lasers, high powered fiber lasers, and other types. We offer simple laser products, as well as sophisticated fiber laser systems with unique characteristics, based on the client’s inquiry. 

Moreover, our fiber lasers are exceptionally light and compact and can be embedded in other devices or used in mobile applications. Our company offers single-mode Erbium lasers and Ytterbium lasers as well as single-frequency fiber lasers (similar to DFB lasers), wavelength-tunable fiber lasers systems, and unique DUV fiber laser system.  We manufacture laser modules using our technologies based on the advanced research work and patents of the international R&D team. Laser processes are of high quality, high precision, easily-automated manufacturing solutions that provide repeatability and flexibility. If you have any questions or would like to buy a fiber laser system, please contact us at [email protected]

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Endoscopic fiber catheter and its applications

An endoscope is an optical device that is used to study hard-to-reach cavities of mechanisms, machines, and equipment. In its simplest form, it is a long flexible or rigid fiber bundle with a lens, optical system, illumination, and eyepiece. In the case when the optical fiber is used for image transmission, such an endoscope is called a fiber optic one, fiberscope or endoscopic fiber catheter.

Light is used to transmit electronic signals over long distances. A single fiber bundle with a thickness of human hair can transmit all the signals necessary for the operation of televisions, telephones, and computers at home or in an institution. Such fibers, also called optical fibers, are usually made of glass or plastic.

The main element of a fiber optic cable or simply optical cable is an optical fiber waveguide. A fiber waveguide, or optical fiber, is an optical waveguide designed for the directional transmission of optical radiation, made in the form of a thin glass bundle of a cylindrical shape with a circular cross-section.

The optical fiber consists of a light-transmitting core, one or several layers of protective-reflective coatings, which prevent the diffusion of light. The fibers are collected in a cable, which can contain from 72 to 144 fibers.

Cables based on fiber optic technology are used in medical equipment and instruments. Standard technology includes the opportunity of inserting a special tool with flexible optical fibers, which can transmit a signal to an external camera inside the organs of the human body. Fiber optics is used in medicine as lighting material. Devices equipped with fiber modules allow painlessly highlighting the cavity of the stomach, nasopharynx, etc.

Modern endoscopic fiber catheters have a fairly complex scheme, which includes the following elements:

● fiber optic probe with stainless steel coating and tungsten covering;  

● fiber optic light guide to provide illumination and light transmission from the source to the distal end;

● lens, interchangeable optics;

● eyepiece;

● body frame.

The design may vary depending on the purpose of use. So, for those cases when it is necessary to use ultraviolet illumination, the optical fiber with quartz fibers are used. The endoscopic fiber catheter must be absolutely dust-proof and waterproof, as well as resistant to aggressive environments, oils, gasoline, etc. The camera can be connected to the eyepiece through a special adapter for recording and documenting, as well as a display.

Endoscopic fiber catheters have a very wide range of applications. Due to the design features and the principle of operation, devices with a fiber optic probe diameter of up to two millimeters are produced, which allows quality control of internal surfaces and hidden cavities of almost any objects to which access by other means is practically impossible: turbines, aircraft wings, heat exchangers, pipelines and pipes of small diameter, etc.

Endoscopic fiber catheters, like their gradient, lens counterparts, are also commonly divided into two very broad categories. The first includes flexible endoscopes (the manipulator of such optical fiber devices can bend at any angle). The second includes devices of rigid type (the manipulator is straight and inflexible). It is flexible endoscopic fiber catheters that are used more actively and are in high demand for obvious reasons. And that's all, even despite the higher price of such equipment.

A rigid endoscope (fiber optic bundle) consists of visual and lighting systems. The visual system consists of a lens, rod or gradient optics, which is enclosed in an internal metal tube. The lighting system consists of an optical fiber that is located between two metal tubes: external and internal.

Rigid endoscopic systems are characterized by four main parameters: the diameter and the length of the working parts, the angle of the observational direction and the angle of the view field. The main advantage of rigid endoscopes is their high resolution - up to 2S lines per millimeter.

Direct access to the object is not always possible or the object itself has complex geometry, for example, gas turbines, electric engines, turbogenerators, boilers, heat exchangers, water pipes, sewers, industrial communications. In this case, flexible endoscopic fiber catheters are used for visual inspection.

The visual system and the light transmission system in flexible endoscopes consist of fiber optics mounted inside a flexible fiber bundle with a controllable distal end.

Flexible endoscopic fiber catheters have a controlled distal end that bends in one or two planes. As a rule, this is determined by the diameter of the working part. The main disadvantage of flexible optical fiber endoscopes compared to rigid ones is lower resolution. It is necessary to pay attention to two main parameters when choosing flexible endoscopic fiber catheters: diameter and length of the working part. 

However, choosing a fiber optic endoscope, you will need to pay attention not only to the flexibility or rigidity of its manipulator but also to whether the case of such a product is waterproof. Resolution is also important. By the way, it is the resolution that is a very important indicator, and therefore it’s worthwhile to research this parameter in a little more detail. By simple and understandable words, the higher the resolution is, the better the quality of the image produced by the endoscopic fiber catheter is considered to be, herewith, such a fiber optic device will be more useful to your needs and the needs of your enterprise.

The main purpose of optical fiber endoscopes is a quick and high-quality visual examination of hard-to-reach cavities of machines and mechanisms without disassembling them. The most illustrative examples by industry are shown below.

● Power industry - endoscopic fiber catheters monitor the state of heat engineering, electrical and other types of power plant equipment. For example, they are used to monitor the condition of the intra-cooling channels, the windings of electric generators and transformers, the inner walls of the pipes.

● Water supply and sewage - optical fiber endoscopes detect damages, corrosion, blockages, cracks and foreign objects in pipes and tanks, they monitor the flowing part of pumping systems.

● Metallurgical industry - fiber catheters are applied for the maintenance of production facilities, for example, inspection of furnace assemblies, as well as for quality control of forming.

● Aviation and space industry - fiber optic sensing systems monitor the state of power elements of hull structures, tank walls, gas turbine blades and compressors, shells, sprayers, nozzles of combustion chambers, as well as they participate in the development and production of rocket engines and pneumatic hydraulic systems.

● Mechanical engineering - endoscopic fiber catheters control the quality of manufacturing and check the technical condition of various components and parts of machines, for example, mold cavities, mechanical transmission parts, bearings, pipelines, soldered and welded structures cavities.

● Security services, customs - fiber catheters are used for the quick search for explosive devices, drugs, weapons, smuggling, for inspecting the contents of opaque containers without opening them, and for a number of other special purposes.

● Architecture and construction - fiber optic bundles check the state of power elements of ceilings, internal cavities, reinforcement and waterproofing of walls, condition of pipelines, as well as architectural modeling.

● Gas pumping stations - fiber sensing systems monitor the condition of the blades, combustion chambers, fuel system and other components of gas pumping units, they check for erosion, corrosion, deposits and fatigue cracks in taps, valves, pipelines, separators, and other systems.

● Chemical and petrochemical industry - optical fiber catheters perform systematic and emergency inspections of pipelines, pressure vessels, heat exchangers, pneumatic and hydraulic units and other devices.

● Automotive industry - they control the quality of manufacture and assembly of engines, for example, the quality of cleaning forming from rods, control hydropneumatic systems, the quality of welding and painting. In operation - sensing systems for monitoring the condition of valves, cylinder liners, gear, corrosion of body parts.

● Rail and sea transport - fiber optic catheters for inspection of diesel and electric engines, generators, transformers, and other units and assemblies.

● Electronic industry - fiber bundles control and ensure the quality of production and assembly of electronic devices.

● Science and education - the systems are employed for observing animals and insects, studying the root system of plants, etc. They include archaeological and exploratory work, an inspection of the internal cavities of statues and monuments.

Medicine

The benefits of optical fibers in medical fiberscopes

Modern endoscopic sensing systems (flexible endoscopes, fiberscopes) use fiber optics. Almost all organs became available for inspection by endoscopic fiber probes, the illumination of the organs under investigation increased, conditions for photographing and video recording (endophotography and endocinematography) appeared, and it became possible to record images on video (on external systems). Currently, endoscopic fiber techniques are used for both the diagnosis and treatment of various diseases.

If you would like to obtain an optical fiber product, you should choose the Optromix company. Optromix is a provider of top quality special fibers and broad spectra fiber optic solutions. The company delivers the best quality special fibers and fiber cables, fiber optic bundles, spectroscopy fiber optic probes, probe couplers and accessories for process spectroscopy to clients. The Optromix product line is based on over 30 years of unique technology experience, which allows these products to have a broad spectral range from 200 nm to 18 µm.

Optromix optical fibers are used in a wide variety of applications, some of which include spectroscopy and process monitoring tasks, IR radiation delivery to and out of closed volumes, thermosensing, laser power flexible delivery systems, IR-imaging, etc. Along with a regular range of products, the company offers custom optical fiber solutions for non-standard tasks and applications. The aim is to deliver the best quality optical fiber systems, high power fiber cables, and spectroscopy fiber probes & fiber bundles to clients, and our custom solutions meet the needs of a wide range of applications, such as reaction monitoring, biomedicine & biotechnology, IR-Fiber pyrometry, laser technology. If you have any questions or would like to buy an optical fiber, please contact us at [email protected]

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Distributed acoustic sensing for railway structural health monitoring

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 [email protected]

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. 

Specially 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. 

The 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.