Thermal Imager wiki

A thermal imager: who is useful and where it is used, how to choose a thermal imager. What is a thermal imager and why is it needed, how to choose the right thermal imager and what characteristics to look for when buying. Varieties and what is the difference from night vision devices. Here is wiki to know it all.

What is a thermal imager?

A thermal imager is a measuring device that allows you to see the thermal (infrared) radiation of surrounding objects at any time of the day, measure the temperature at any point on the surface with an accuracy of 0.1 ° C and higher. The main purpose of the thermal imager is non-contact temperature measurement of objects of living and inanimate nature, troubleshooting of equipment and electrics, construction defects. Thermal imaging cameras create sharp thermal images based on temperature differences. And complex algorithms of simple-looking cameras read temperature values ​​from these images. The hottest places are colored in red, yellow and orange, the coldest in blue and black. Thermal imagers gained popularity due to the possibility of application in all branches of human activity. The most popular areas of application are construction, hunting, medicine and industry. Increasingly, thermal imagers are also used in everyday life to inspect apartments and private houses, allow you to find places of heat leaks and electrical problems.

Principle of operation of the thermal imager

The principle of operation of the thermal imager is based on the registration and analysis of surface temperatures of objects. Each of the materials has its own ability to reflect and absorb infrared radiation. The uneven heating of the same surface allows you to form a picture of the temperature distribution on it, associating the color on the display with the temperature. In this case, the temperature resolution is 0.05-0.1 degrees. Features of the spectral range of 8-14 microns and 3-5.5 microns, in which thermal imagers operate, are such that the surface layers of the atmosphere are the most transparent for a given wavelength, while providing the greatest observation range for objects emitting in the temperature range from -50 to + 500 degrees. In this frequency range, the least interference from atmospheric phenomena is fog, rain, snow, smoke.

What a thermal imager sees

he human eye sees a very small part of the electromagnetic spectrum. Our “detectors” are imperfect, we perceive only visible light, infrared radiation is beyond the capabilities of our eyes. Visible light occupies a wavelength range of electromagnetic radiation from 0.38 to 0.76 microns, with the middle of this range falling at a wavelength of 0.55 microns, which corresponds to the maximum solar radiation. Since the entire range of electromagnetic radiation extends from angstroms to hundreds of kilometers and is in fact not limited to either the “left” or “right”, human civilization, throughout its technological history, seeks to master those radiation ranges where the human eye is powerless. IR radiation is in the range between visible light and the microwave range of the electromagnetic spectrum. Infrared (IR) radiation covers the wavelength range from 0.76 to 1000 microns. The main source of infrared radiation is heat or thermal radiation. Any object with a temperature above absolute zero (-273.15°C or 0 degrees Kelvin) emits radiation in the infrared region. Even objects that seem very cold to us, such as ice cubes, emit IR rays. In other words, if the human eye could see in the IR range, then we could estimate the temperature of objects without touching them. The heat of the sun’s rays, a fire or a heating radiator – all this is infrared radiation. Although the eyes do not see it, our subcutaneous nervous system perceives this radiation as heat. The warmer an object, the more IR radiation it emits. The infrared radiation emitted from the object is focused by the lens of the thermal imager on the infrared detector. This detector transmits a signal to the electronic unit for image processing. The electronic unit converts the signals from the sensor into a thermal image that is displayed in the viewfinder, on a standard monitor or LCD. And by converting the infrared image into a radiometric one, the temperature values ​​are read from the thermal imaging image.

Infrared vision of animals

Man “peeped” a lot from nature, creating his own devices and mechanisms. In wildlife, there are natural analogues of thermal imagers. Special organs that capture thermal radiation are present in a number of animals. For example, snakes use a molecular algorithm to process data about the outside world. This sensory system, called pits, allows you to choose from the whole variety of warm objects that exist in the outside world only those that move and are of particular interest for food. The structure of such an organ is quite simple. Near each eye there is a hole about a millimeter in diameter, which leads into a small cavity of the same size. On the walls of the cavity there is a membrane containing a matrix of thermoreceptor cells approximately 40 by 40 cells in size. These cells do not respond to the “brightness of light” of heat rays, but to the local temperature of the membrane. The snake’s sixth sense organ works like a camera obscura, the prototype of cameras. A small warm-blooded animal against a cold background emits “heat rays” in all directions – infrared radiation with a wavelength of about 10 microns. Passing through the hole, the rays locally heat the membrane and create a “thermal image”. Due to the high sensitivity of receptor cells (a temperature difference of thousandths of a degree Celsius is detected!) and good angular resolution, a snake can spot a mouse in absolute darkness from a fairly large distance. Deep-sea squids have another version of “thermal” vision. In addition to the usual eyes, on the lower surface of the body of the squid there are special organs that capture infrared rays. Their device is similar to an ordinary eye, which at the same time has an additional light filter that absorbs all other rays, except infrared, and is located in front of a refractive lens-crystalline lens.

What can a thermal imager do?

In the process of thermal imaging diagnostics, as well as when performing an energy audit, using a thermal imager, places with abnormal temperature deviations are identified, that is, the device is most often used as an indicator. Most thermal imagers can not only obtain thermal images of objects, but also determine the surface temperature at individual points. By detecting “overheated” elements, the thermal imager allows you to detect malfunctioning units of mechanical units that are subject to increased friction, defects in contact connections, switching equipment and current-carrying lines of power electrical equipment. In the construction industry, thermal imaging is used for energy audits, checking the quality of construction and installation works (including checking the correct installation of window blocks, thermal insulation, etc.), searching for leaks and hidden defects, identifying places where mold can appear, diagnosing electrical networks and switching equipment, checking the operation of heating systems, etc. Classification of measuring thermal imagers by application: for inspection of electrical equipment and electricians; to search for heat-cold leaks; to search for gas leaks / oil spills; for control and automation of technological processes; for scientific research.

Main characteristics and price of the thermal imager

To the greatest extent, the price of a thermal imager depends on the resolution of the IR sensor, temperature range, range (larger germanium lenses are more expensive) and additional measurement functions. The most inexpensive thermal imager today can be bought for 1000 Euro. For this price you will get a simple device that is suitable for everyday needs in everyday life. The most expensive models are professional thermal imagers with a large matrix for energy audits, technical and industrial diagnostics, they cost from a million or more. Consider the main characteristics of thermal imagers. The resolution of an infrared detector is the main characteristic that determines the functionality of a particular model and the “efficiency” of thermography. The most affordable are models with a resolution of 60×60, thermal imagers of the upper price range have a resolution of over 640×480. It is important not to confuse the resolution of the IR detector with the characteristics of the built-in visible camera and the resolution of the instrument’s display. The resolution of a thermal imager is the number of individual “measurement points” horizontally and vertically displayed on an image. Outwardly similar models with the same screen size, but with a different resolution of the IR matrix, will show similar “images” during the shooting process, however, upon detailed examination of the thermogram on a computer (or after printing a full-size image), the difference will be noticeable – to get a quality of 120×120 using thermal imager with a resolution of 60×60, you need to take 4 shots at close range. In most cases, low-resolution basic models are used for operational diagnostics of electromechanical equipment, switching and electric power equipment, searching for leaks, determining sources of heat loss in rooms, etc. Models of thermal imagers with a resolution of 120×120 successfully cope with the tasks of energy auditing of buildings up to 5 floors high. For thermal imaging inspection of large objects, models with a resolution of 320×240 (for buildings up to 16 floors) and 640×480 are usually used. Thermal imagers with high resolution allow you to get high quality thermal images “in one go”, however, even with a model of a lower class (with “weak” resolution), you can get the same results by taking a series of images and “stitching” them using the appropriate software (Some fixtures have a special pan feature that makes this easier.) Additional “optics” (interchangeable lenses) allow you to expand the capabilities of the thermal imager by performing a general thermal imaging survey using a wide-angle lens, such optics are convenient if the object is close to the operator and you want to view as large an area as possible (scientific research, construction and energy). For detailed images of distant objects or individual elements (for example, the upper floors of buildings, power transmission towers, chimneys, IR shooting from a helicopter) – using a telephoto lens.

It should be borne in mind that wide-angle lenses increase the “angle of view” of the device, and telephoto lenses narrow it. In professional thermal imagers, an IR lens is a complex assembly that includes a set of lenses and mirrors made of fragile, expensive materials that require precision processing such as silicon, germanium, and special IR glasses. The main parameters of lenses that are important to the consumer are the focal length and the angle of view. The temperature range in which the thermal imager can measure (or the range of controlled temperatures) determines the scope of the instrument. For thermography of buildings, thermal imagers with an upper temperature range of up to +100 ° C are quite suitable, for diagnostics of electrical installations and industrial units, devices capable of measuring up to + 350 ° C are required, and for testing boilers, heat generators, etc., more “high-temperature” models are needed ( up to +650°C). In the foundry, glass, chemical, and energy industries, where temperatures can reach up to +1200°C (or higher), thermal imager models with the appropriate temperature range are used. When choosing a thermal imager, of course, one should “leave” a certain “temperature margin”, however, it is not worth overestimating the requirements for the temperature range – this is an unreasonable expenditure of funds. Sensitivity is the value of the minimum temperature difference that a thermal imager can detect. The “contrast” of the resulting image depends on this characteristic. For energy audits, a sensitivity of 0.1°C is sufficient. Less sensitive models can also be used to detect “overheated” components of electrical power or mechanical equipment. Increased sensitivity is required to detect areas with high humidity, leaks, hidden defects, etc. Measurement accuracy (error). Almost all thermal imagers (with an uncooled bolometric matrix) provide measurement accuracy of at least 2%, which is quite sufficient for solving most diagnostic and energy audit problems. Nitrogen-cooled models, which are more commonly used for scientific research and process control, provide higher accuracy. Spectral range. To perform most tasks (for example, thermal imaging of buildings), thermal imagers with a spectral range of 7-14 microns are used. Shooting of buildings with continuous glazing is provided by models with a spectral range of 3-5 μm (with a cooled matrix), which allow determining the surface temperature of glass-like objects without taking into account their reflectivity. The screen size of a thermal imager is important for operational thermal imaging, when you need to quickly and without errors identify a malfunction on the spot. For an energy audit, this characteristic is not so important, because when compiling reports, the quality of images is determined only by the resolution of the IR sensor.

Additional features

Most thermal imagers (except budget models) are equipped with built-in video cameras with an image storage function, which makes it possible to overlay (full or picture-in-picture) images of infrared and visible spectra. Models of the upper price range allow video recording. For more efficient processing of the results of thermal imaging diagnostics, the functions of annotating thermograms, as well as their positioning (using the built-in compass or GPS), are useful. To diagnose and identify areas of mold formation, the functions of temperature alarm and detection of areas with maximum and minimum temperature indicators are in demand. When choosing a thermal imager, you should definitely familiarize yourself with the capabilities of the software (if it is supplied with the device), or purchase special software separately.

Manufacturers of thermal imagers

There are more and more manufacturers of thermal imagers every year, competition is growing, new brands are emerging, but not all of them deserve attention. Here are a few brands that you can safely buy without worrying about the money spent. Investments in reliable and high-quality equipment will pay off.

How to Choose a Thermal Imager

Contents Since a thermal imager is a versatile instrument for measuring temperature and analyzing thermal fields, you may be tempted to use it for a wide range of measurement and diagnostic applications. This is the first thought you should get rid of when choosing a camera. When buying a thermal imager, the first thing to be clear is the main areas of its further application, the second is to decide on the budget. The third is the matrix of the thermal imager, the more accurate its resolution and frame rate, measured in Hz, the higher the resolution of the matrix and the higher the frame rate, the better the picture. Thermal imagers for perimeter protection Unlike measuring cameras, security thermal imagers do not measure the temperature of objects, they have other tasks. Using a thermal imager as a “long-range” and highly sensitive night vision device will require you to purchase long-focus optics, but does not require temperature measurement functions. The security thermal imager must provide clear images of the intruder at long distances at the maximum operating temperature range in order to exclude false alarms from security systems. Pay attention to the resolution of the matrix of the thermal imager, the larger it is, the clearer the picture, but the thermal imager itself is also more expensive. Models: rotary thermal imaging system RTR-100F with a human detection range of up to 3000 meters; multi-sensor system PTP-225M with a resolution of 640 x 480 for the protection of critical facilities; PERGAM S140 gyro-stabilized optical-electronic video surveillance system based on a thermal imager with a matrix resolution of 640 × 512 pixels;

Simple low-cost thermal imagers up to 1000 Euro.

Simple low-cost devices for everyday needs (thermal imaging inspection of an apartment, summer house, house, checking electricians, troubleshooting car wiring, underfloor heating, etc.) include models: a miniature thermal imager for a FLIR One Pro smartphone with a matrix of 160×120 pixels; moisture meter with built-in thermal imaging module FLIR MR160 with a matrix of 80×60; Guide BritIR B0 – inexpensive thermal imager for inspection of electronics and electrical wiring; budget thermal imager testo 865 with a matrix of 160 x 120 pixels for maintenance and installation work in construction and industry. Here, the choice is simple. Look at the resolution of the matrix, the more the better. It is better not to take cameras with a resolution of 80×60 for everyday needs at all, the picture is very small and illegible, you can’t make out anything on it. But if you need a device that will replace a boring point pyrometer, then a baby with such a matrix will do just fine. Even when choosing, pay attention to such a function as a picture in a picture or an overlay of a visible image on a thermogram. Each manufacturer has its own name, for example, Flir has MSX.

Thermal imagers for construction and electrical equipment

Inspection of buildings and structures with a thermal imager allows you to identify heat leaks in a building, in the energy sector – to find the causes of electrical equipment malfunctions. For IR diagnostics in construction and energy, cameras with a matrix resolution of 320 x 240 pixels and a digital zoom function that allows you to see more details and create thermograms with a resolution of 640 x 480 and 1024 × 768 pixels are the best choice. In the conditions of the Russian harsh climate, an important parameter is the range of operating ambient temperatures, since the inspection of construction sites is more often carried out in winter, when the temperature difference between indoors and outdoors is maximum. Very often, temperature inhomogeneities are too small, a few degrees, which is why the heating season is the ideal time to inspect buildings. The greater the temperature difference, the easier it is to detect energy losses. The temperature difference between indoor and outdoor air during thermal imaging inspection of buildings should be at least 10°C – 15°C. The higher the temperature difference, the more accurate the test results. The ideal conditions for a thermal imaging survey are a clear windless evening, the indoor temperature is +(20-25)⁰С, and the outside temperature is (0-10)⁰С or lower. If you plan to inspect a house or commercial facility during the warm season, when the temperature difference is minimal, we recommend using an air door to create additional thermal pressure. According to the Department of Energy, fixing defects found during inspections of building envelopes can reduce energy costs by at least 15%. The following models are suitable for energy audit of buildings and enterprises: FLIR T1020 – a professional thermal imager for energy audit with an IR matrix of 1024 × 768 pixels; FLIR T540 – a thermal imager with a rangefinder, a removable lens and built-in GPS, a matrix with a resolution of 464 x 348 pixels; professional measuring thermal imager Guide C400 with GPS and Wi-Fi, matrix 400×300 pixels; thermal imaging camera Guide C640 Pro with a 640×480 matrix, temperature measurement range from -20 to +2000ºC, a large selection of interchangeable lenses with a sensitivity of F1.0 and F1.1; Fluke TiX1000 thermal imager with 1024 x 768 pixels, 32x zoom, sensitivity ≤ 0.05°C;

Choosing a medical thermal imager

Thermography has long been used in medicine, but has not yet received mass distribution. Not all clinics can afford to buy a thermal imager for examining a person. In medical thermal imagers, a matrix with a high resolution of 384 × 288 pixels and a high frame rate of 30-60 Hz for a high-quality thermal image, the price of a thermal imager is appropriate. All medical thermal imagers have their own software for analyzing and processing thermal images and videos. In our arsenal there is one medical thermal imager – PERGAMED-Diagnostics. This is a fairly accurate device, the accuracy of measuring surface temperatures is 0.3 ° C. Such accuracy is achieved through the use of a blackbody (black body) as a calibrator. Medical thermal imagerMedical thermal imager PERGAMED-Diagnostics Thermal imaging examination of the human body is used to diagnose diseases in the early stages (in some cases, long before the patient’s complaints) of a wide range of diseases. The thermal imager registers its thermal radiation from the surface of the human body, places where the body temperature is elevated are painted in red-yellow hues, elevated temperature is a sign of inflammation. Thermal imaging examination allows you to identify: inflammatory processes and tumors of various organs, lesions of the nerves and arteries of the extremities, varicose veins; neurological manifestations of osteochondrosis of the spine, etc. With the help of a thermal imager, functional disorders of the autonomic nervous system can be detected. With thermal imaging, visualization of endothelial dysfunction is possible. Advantages of the thermal imager as a diagnostic tool Absolutely safe for the patient. There are no harmful radiations, for example, as with x-rays. Thermal imaging inspection can be assigned an unlimited number of times. This is very important for the timely correction of physiotherapy treatment. Precision and high sensitivity. On thermograms of the body surface, which are analyzed by software on a computer, the temperature of different parts of the body can differ by tenths and hundredths of a degree, such a temperature difference is very important for a correct diagnosis. Large amount of data for analysis. With the help of a medical thermal imager, it is possible to examine not only the entire human body, but also to accurately study its individual parts, for example, for the presence of tumors that are not visually noticeable at an early stage. Thermal imagers are rapidly becoming cheaper every year, becoming available to a wide range of consumers. If earlier they cost several tens of thousands of dollars and were available only to military and large companies, today you can buy the cheapest thermal imager from us for 1000Euro. If you need a measuring or security thermal imager, a pyrometer with a built-in IR module, a video surveillance system based on high-resolution thermal imaging modules, please contact us, we will help you make the right choice.