Application of Infrared Thermal Imaging Technology in Civil Field
- Issue Time
Thermal imaging technology is playing an important role in many fields, such as civil aviation, security, border defense and automation. This paper briefly introduces the basic elements and characteristics of infrared thermal imaging technology and then discusses in detail its application in seven fields.
Since all objects above absolute zero emit infrared light, infrared thermal imaging technology is to absorb the infrared light radiated by the target object and then converts the light signal into an electrical signal, that is, converts the infrared radiation invisible to the naked eye into a visible image. At the same time, there are three infrared atmospheric windows: 1-3um (short wave), 3-5um (medium wave), and 8-14um (long wave). Infrared thermal imaging usually works in the mid-wave infrared and long-wave infrared bands.
This technology is widely used in various fields, and has the following characteristics:
(1) The temperature measurement range is wide, usually-170 ~ 2000℃(or need to add a filter);
(2) The detection accuracy is high, and the resolution is less than 0.1℃temperature;
(3) The response time is short, the temperature field of the object can be measured in a few seconds;
(4) It can be used to measure small targets or point to target objects;
(5) It is a passive measurement and will not damage the temperature to be measured field (temperature measurement distance can be close or far, from a few centimeters to astronomical distances).
Infrared imaging can be used in infrastructure construction, urban management, industrial production, traffic control, resource exploration, inspection and quarantine, fire security, and other fields, and the market demand is broad. Due to its wide application and great convenience for production and life, the market demand for infrared imaging may maintain a sustained and stable growth trend in the future. In addition to traditional application industries, there will be more emerging market demands that will become a new growth point for the infrared imaging market.
At present, the application of infrared thermal imaging technology is becoming more and more popular, involving many fields such as civil aviation, security, border defense, industry, construction, transportation, outdoor, and automation. The applications of infrared thermal imaging in seven fields are described in detail below.
1. Civil aviation
With the continuous development of modern aviation science and technology, the safety of civil aircraft is getting higher and higher. After being equipped with the Integrated Surveillance System (ISS), the aircraft can provide the crew with the comprehensive ground and air traffic, flight meteorology, complex landforms, and other information, which continuously enhances its ability to perceive the air environment.
However, the ISS system only solves the safety problems of the aircraft when flying in the air; it cannot provide effective solutions for the safety problems when landing or being located on the runway under conditions of low visibility such as heavy fog or thunderstorms. The existing ISS system has two defects: first, the pilot cannot be fully informed of the runway situation when the aircraft lands; second, the aircraft cannot detect and recognize the surrounding environment when moving on the runway, which often leads to collisions with other aircraft, injury to ground staff and other accidents.
This deficiency can be compensated by adding an infrared assistance system under the front of the aircraft. Since infrared thermal imaging technology can detect and identify the runway and the surrounding environment, the take-off and landing level of the aircraft can be improved by navigating with the help of infrared visual images, thereby improving the safety of aircraft take-off and landing
2. Electric power industry
The electric power industry is currently the most mature and stable application in the field of preventive inspection. As the most effective online power detection method, infrared thermal imaging technology can quickly repair power equipment, thereby effectively reducing the time cost of equipment maintenance and improving the reliability of equipment operation.
There are many advantages of using infrared thermal imaging for power inspection: it is far away from equipment and has strong safety; non-contact temperature measurement does not affect the operation of equipment; fast scanning speed saves time; it has a wide temperature measurement range and high precision; the thorough monitoring can accurately detect the defects of the equipment. Power generation, distribution, and substations in important areas can be equipped with high-end infrared imaging monitoring equipment.
3. Forest fire prevention and environmental monitoring
The surface temperature information of the object can be extracted and quantified from the target image observed by the thermal imaging camera. This feature can be used in the field of fire prevention. In a large area of forest, inconspicuously hidden fires are easy to cause large fires, and it is difficult to detect in time only by manual monitoring, and it has developed into a situation that is difficult to control when discovered.
The high-sensitivity infrared thermal imager can perform real-time analysis of the monitoring target by setting the upper limit of the target temperature. If the target temperature reaches the set upper limit, an alarm message will be issued, so that the location and scale of the fire point can be quickly determined, and the forest fire can be eliminated in the budding stage, thereby eliminating the fire hazard.
4. Medical field
The human body itself is also a source of infrared radiation, and its tissue cells generate heat and transmit it to the body surface in the process of metabolism. When normal or pathological changes occur in a certain part of the human body, the surface temperature of that place will deviate from the normal value.
Medical infrared cameras can map this part of the change into a temperature map. As a non-invasive, non-contact, non-radiation, green auxiliary diagnosis technology, medical infrared thermal imaging has the characteristics of high sensitivity, comprehensiveness, and quickness, and can play the role of early screening, early diagnosis, and full dynamic monitoring, thereby achieving the goal of "curing the unformed disease".
It is known as one of the five major medical imaging technologies, the other four being nuclear magnetic resonance, CT, X-ray, and ultrasound. The main applications of medical infrared thermal imaging technology include physical identification, chronic disease prevention/control (elderly health care), major disease prevention, common disease diagnosis, comprehensive evaluation of sub-health, rehabilitation services, mental health inspection, TCM syndrome differentiation, and efficacy evaluation, etc. The application of this technology in the medical field has just started. Our society will gradually enter the elderly society, so thermal imaging cameras have a huge application market in the medical field.
5. Security monitoring
The application of infrared thermal imaging technology in security includes anti-theft monitoring, camouflage, and concealed target recognition, security patrols at night and in harsh weather conditions, security work in key departments, buildings, and warehouses, fire monitoring, land, and port security, airport surveillance and other fields. High-end infrared imaging equipment has the advantages of high concealment, low false alarm rate, and no need for any auxiliary light source at night.
Ports, airports, nuclear power plants, etc. are important areas that are prone to theft and even terrorist attacks. A thermal imager can play an important role in protection. Airports, hydroelectric power plants, refineries, oil and gas pipelines, and any other large infrastructure may have enclosure boundaries that can be several kilometers long. At this point, thermal imaging cameras can provide them with a safe perimeter alarm solution. During the SARS period in 2003, infrared thermal imaging technology has been used in security inspections, which yielded good results.
In addition, thermal imaging cameras can also be used for monitoring and early warning of "low, slow, and small" targets such as drones, aviation models, and airborne balloons. Since such targets have the characteristics of small radar scattering areas and slow speed, it is difficult to monitor them by radar technology. Infrared thermal imaging technology is not limited by the above characteristics. It can monitor and warn the "low, slow, and small" targets in the airspace in real-time, so as to achieve effective detection and expelling of "low, slow, and small" targets.
6. Maritime field
Infrared thermal imaging technology is efficient and practical in the marine environment and can meet the following needs: port, waterway, and coastal security, maritime security, maritime illegal entry detection, maritime law enforcement, anti-piracy and threat detection, fishing fleet protection, ship tracking, and observation, search and rescue operations, and environmental protection. Even objects that cannot be detected by radar systems (such as sailboats, wooden boats, and floating objects) can be detected using infrared thermal imaging technology.
Thermal imaging cameras can provide an "early warning system" against common hazards, showing invisible thermal energy from potential hazards, including floating objects, airline traffic, anchored ships, small crafts, and artificial constructions such as piers. They can also identify icebergs and shallow swimming whales.
Thermal imaging cameras can help tankers navigate ice-covered waters safely, and see everything at night, including any detail on other ships such as the cockpits, bridges, anchors, and more. At the same time, it can also be used for maritime search and rescue missions. Search and rescue personnel can use infrared thermal imaging cameras to accurately find and locate victims, and then successfully carry out underwater search and rescue work.
Infrared thermal imaging technology can also help maritime personnel understand the dynamics on land, delineate alert areas around crime scenes or search areas, and provide law enforcement officers on land with observed information, which is conducive to the safe cooperation of maritime and coastal law enforcement officers.
7. Industrial manufacturing
Infrared thermal imaging technology also has a wide range of applications in the field of industrial manufacturing. As electronic components get smaller and smaller, it becomes extremely difficult to accurately get their thermal information. With infrared thermal imaging, engineers can easily visualize and quantify thermal images of manufacturing equipment. At the same time, in the early stages of circuit design, thermal imaging can be used to pre-optimize the design.
When the microscope is combined with infrared thermal imaging technology, it becomes a thermal imaging microscope that can accurately measure the temperature of objects as small as 3um. Using thermal imaging microscopes, researchers can characterize the thermal properties of components and semiconductor substrates without contact.
Infrared thermal imaging technology can help automotive engineers improve airbag system design, verify the efficiency of heating and cooling systems, quantify the effect of thermal shock on tire wear, inspect the performance quality of joints and welds, and more. New drug research and development can also benefit from infrared technology. Scientists study the changes that take place in the titration dish by observing temperature changes in chemical reactions. With the help of infrared thermal imaging technology, the manufacturing industry can shorten the research and development cycle and improve the product quality, thereby increasing the company's profit.
Infrared non-destructive testing is a widely used method for evaluating the properties of materials, components, and systems without causing damage to the object being inspected. Infrared thermal imaging technology can not only complete various advanced inspections such as non-destructive testing, stress mapping, and surface cracks detection but also can be used to detect small temperature differences as low as 1mK. Infrared NDT can detect internal defects by observing thermal differences on the target surface based on target excitation. This technique is valuable for detecting voids, delamination, and water occlusion in composites.
Stress testing and fatigue testing are common test methods in mechanical engineering and materials science, but they can only provide limited information on complex structures. Infrared thermal imaging for thermal stress mapping can provide thousands of stress measurements simultaneously, even for geometrically complex components. This technique provides researchers with more timely and more complete information compared with strain gauges.
After years of accumulation, infrared thermal imaging technology has realized functional modularization, miniaturization, electronization, and full automation, and has the characteristics of high sensitivity, fast response, harmless to the human body, easy maintenance, and long service life.
Uncooled thermal imaging technology is widely used in industrial production monitoring, public safety law enforcement, safe city construction, medical auxiliary diagnosis, civil satellite remote sensing, equipment preventive fault diagnosis and maintenance, maritime law enforcement, galaxy deep space exploration, and civil areas such as driver assistance.
With the continuous development of cooled infrared detector technology, the cost of high-performance, large-area, high-reliability, and high-resolution infrared detectors will gradually decrease, making cooled infrared thermal imaging cameras more and more popular in high-end civilian fields.
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