Thermal cameras and thermal imagers

What are thermal imaging cameras?

Thermal imaging cameras are modern devices that record and change the image seen by the eye into a thermal image using infrared radiation. The resulting image represents the temperature of the object in question, and allows for simple image registration using the temperature difference. Thermal imaging cameras and thermal imaging cameras are the same device.

Infrared radiation is part of the electromagnetic spectrum, but unlike visible light (which is also part of it), it is completely invisible to the human eye. It is due to this that light has no effect on thermal imaging cameras, so regardless of the time of day or night, the image remains just as clear.

Interestingly, thermal imaging camera technology was first used for the military.

How do thermal imaging cameras work?

Thermal imaging cameras generate images based on temperature differences. The device uses infrared radiation in the selected electromagnetic wave range of the infrared detector, which is installed in the thermal camera. The thermal imager measures and images the infrared radiation that comes from the object.

It should be noted that the value of the radiation is a function of the surface temperature of the object in question, so it is possible to calculate and image these values. It is also important to note that the energy received through the camera depends not only on the temperature of the object itself, but is also a function of emissivity.

Radiation also comes from the environment and is reflected by the object. The object's radiance and reflected radiation are also affected by the absorption of the atmosphere, so in order to accurately measure the temperature, the effects of different radiation sources must be compensated for. Thermal imaging cameras do this fully automatically - you only need to enter the following parameters into it:

• emissivity of the object,
• ambient temperature,
• the distance between the object and the camera,
• relative humidity,
• temperature of the atmosphere.

The thermal image shows a range of colors from dark blue to red, where the hottest elements are marked as red, and the coldest elements are marked in blue.

What are the functions of thermal imaging cameras?

Thermal imaging cameras are created to be used on a daily basis and in all conditions. en.ivel.pl offers handheld thermal imaging cameras capable of detecting gas, able to identify problems in electrical installations or mechanical equipment.

Some of the thermal imaging cameras are equipped with a pistol grip, so we can actually with one hand, with the click of a button, efficiently and quickly find and remove the fault.

How to choose thermal imagers?

Thermal imagers are characterized by a number of parameters that are worth paying attention to if you want to buy the right device to look at when purchasing.

Sensor resolution - this is undoubtedly one of the most important parameters. As a rule, thermal imaging cameras have quite small resolutions (compared to all sorts of other cameras). Typical sensor resolution for cheaper thermal imagers is 384 x 288 pixels, and the image from such a thermal imager - although not very detailed - is sufficient and quite useful. Resolution alone should not be the deciding factor in the choice.

Thermal sensitivity - this value determines the smallest temperature difference between two registered objects allowing to distinguish between them. Often referred to as NETD in technical parameters, it is expressed in mK. The smaller the NETD value, the better the quality of the observed image.

Frame rate - is a value expressing the frequency with which the thermal image is refreshed. The most common values are 50 Hz, 30 Hz and 9 Hz, with most manufacturers using just 50 Hz. A high refresh rate ensures correct image reproduction for objects that move quickly.

Lens parameters - in the case of this value, a lot depends on the type of thermal imager - you should thoroughly study the specifications of the thermal imaging cameras you choose. The most common lenses are those with an aperture of f/1.0 and f/1.2, and the longer the focal length, the more magnified the image and the smaller the field of view.

Field of view - this variable depends on the size of the sensor, which in turn depends on the resolution and pixel size. We can expect the largest fields of view for high-resolution thermal imagers with lenses of short focal length. In some simplification, we can say that the higher the magnification, the smaller the field of view.

Magnification - this value is the product of many factors, such as the focal length of the lens, the size of the sensor, the size of the display or the magnification of the optical system.

Display - the importance of a good display is extremely often downplayed. This is a mistake, because a suitable display should have good resolution and high contrast, as well as an optical system that works with the screen, which should produce an image that is well magnified and free of distortion.

Laser rangefinder - in thermal imaging devices, the problem of determining distance becomes quite important, since the intensity with which an object is seen does not allow us to fully determine the real distance. That's why a built-in laser rangefinder is a very valuable addition to thermal imagers.

Where can we use thermal imaging cameras?

Thermal imaging cameras are used in the energy industry and the construction industry. Thermal imaging can be used to see how much heat is escaping from a building and check the quality of its insulation, for example. We can also monitor water ingress into the house, as thermal imaging cameras can record cold spots on the wall or plaster. This allows us to prevent rising heating bills or moisture-damaged walls or floors. Thermal imagers are also used to determine the location of electrical cables in a wall.

Law enforcement and police also use thermal imagers almost daily. Thermal cameras come in handy for tracking down criminals - they can show people hiding in the darkness of a forest or, for example, fresh tire tracks of a car. Police also use them to track illegal activities, such as growing cannabis, which needs heat to grow. Buildings therefore emit invisible to the eye infrared radiation more strongly than other buildings.

Small temperature differences can effectively pinpoint hidden stashes in walls and items hidden under clothing like weapons. Also, services that guard national borders use this type of equipment to detect illegal smuggling or immigration, among other things.

Thermal imaging cameras are also used in special situations by emergency services, for example. Searching for victims of disasters, missing persons in the mountains or early detection of fire danger in the forest are just a few examples of situations in which thermal imagers prove indispensable.

Thermal imagers are also used in industry and manufacturing. The devices are actually indispensable wherever control and continuous monitoring of processes and machinery is needed.

Finally, thermal imaging cameras are also used in medicine and veterinary medicine - thanks to the temperature difference, we locate inflammation in the body faster. This reduces the time used for diagnosis, so we can implement treatment more quickly.