Thermal imaging and 7 practical tips about it

What is thermal imaging?

Thermal imaging scan, or simply thermal imaging, is a process that converts infrared radiation (heat) into an image of the temperature differences present in a snapshot taken by a thermal camera. In thermal imaging systems, infrared imaging cameras feature infrared detectors that usually consist of arrays of micron-size sensors or pixels.

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Depending on its materials and intended use, a camera’s array can either be cooled or uncooled. Radiation from the scene is focused onto the detector array by a lens system, and processing electronics display the image. Atmospheric conditions greatly influence the amount of attenuation of infrared radiation as long as it is collected during a time of low attenuation. The detector response must be matched with either the mid-wave IR (MWIR) or longwave IR (LWIR) atmospheric windows.

What is thermal imaging?

We are not concerned with measuring the temperatures of objects present in the scene during most survey work or field observations but rather only with the evident temperature differences between objects present. Note that this is an improvement over the level of difficulty that most thermographers face when conducting field measurements, but it does come with its own set of requirements.
An essential component of the process of detecting, recognizing, and identifying animals of interest in the field is the creation of the best images possible. For years, the military has been working on surveillance applications with this objective in mind.

As early as the 1950s, the military developed the first thermal imaging cameras. These cameras were very large, heavy, and expensive. Those cameras had to be cooled with liquid nitrogen in order to function. Since the beginning of the development of thermal imaging cameras, new detector materials, array fabrication techniques, software, optics, electronics, coolers, and packaging have been developed that have resulted in reliable, high-performance thermal imaging devices. Midway through the 1990s, most focal plane arrays were cooled and new imagers began to incorporate uncooled arrays.

A focal plane array can be either cooled or uncooled today. Thermal imaging technology is mainly discussed in books devoted to the development of thermal imagers and detector arrays for use in commercial rather than military applications, such as long-distance surveillance and target identification.

What is thermal imaging used for?

According to a historical analysis of the development of thermal imaging, it originated during the Korean War, when it was employed to conduct scouting missions and combat missions at night. Since then, its applications have spread dramatically in many different fields and for many different reasons.

Electrical maintenance image

applications of thermal imaging in electrical maintenance are numerous. , For instance, Thermal imaging is used by power line technicians to identify and pinpoint parts and joints that could overheat since they already emit more heat than the more robust sections. This also helps to locate loose connections and failing devices.

Plumbing image

Thermal imaging devices are used by plumbers to find leaks in walls and pipes. They can be used from a distance, which makes them ideal for identifying potential problems with equipment that is hard to reach or otherwise might pose a safety risk to workers.

Building construction thermal imaging

A mechanical technician or a building construction specialist who works with thermal insulation often uses thermal imaging to find leaks, allowing them to maintain temperature regulation in a building efficiently. They can see faults and analyze the structure of a building at a glance. Thermal imaging can detect heat loss from walls, HVAC equipment, doors, and windows.

Termite pack inside and on wall image

There are a surprising number of thermal imaging applications in the field of animal and pest management. These cameras can help spot pests or animals that are hiding in dark roof areas without having to climb on top of them, as well as detect potential termite activity. In addition, they can better facilitate wildlife surveys in a non-intrusive manner without affecting wildlife.

Transport image

The development of thermal imaging technology has made travel navigation easier, particularly for nighttime travel. Maritime navigation, for example, utilizes it as a means of viewing other vessels, people, and obstructions during the nighttime while at sea. Detecting animals and people beyond streetlights and headlights has become more common by incorporating infrared cameras in cars.

Airport image

Detecting fevers and temperature anomalies can be done with the use of thermal imaging in the medical field. Thermal imaging cameras have proven particularly useful in airports since they can quickly and precisely scan incoming or outgoing passengers for higher temperatures, which was essential during recent outbreaks of diseases like Covid-19 and Ebola. In addition, thermal imaging has been proven to be helpful for diagnosing neck, back, and limb conditions, as well as circulatory disorders.

Fire image

During rescue missions, firefighters use thermal imaging to see through smoke and find people in otherwise obscured and risky environments. A thermal camera can also be used to identify spot fires quickly so that they can intervene before they spread.

Other uses of thermal imaging

Thermal imaging is incorporated into the surveillance equipment of police and law enforcement agencies, as it helps the officers locate suspects at night, as well as to investigate crime scenes and also carry out search and rescue operations. Their advantage over night-vision devices is that they require no ambient light and are not affected by bright lighting, which is essential for tactical missions. Science and research are undoubtedly sectors that draw significant benefits from using thermal imagers, for accurate and precise visualizations of heat patterns. Thermal imaging cameras are used in a wide range of applications, such as heating, ventilation, air conditioning, mold detection, quality assurance, and many others.

We will answer the most frequent questions about thermal imaging in the following.

Is it possible to see through glass with a thermal camera?

Thermal imaging cameras are not typically able to work through glass.
It would be a bit complex from a physics standpoint to explain everything that’s going on here, but the basic principle isn’t complicated. Glass acts as a transparent sheet while reflecting infrared wavelengths (this is why the lenses on IR cameras are typically made of germanium or zinc selenide.)

You wouldn’t likely see a thermal image of what’s on the other side of a window if you held a thermal camera up to a window, but a blurry mess – possibly including your reflection!
There’s no absolute rule about infrared passing through glass; some infrared frequencies can pass through, while certain types and configurations of glass allow for varying amounts of infrared transmission. Compared to household glazing, car windscreens tend to perform better.

Even though, most often, the image of the screen will be obscured by infrared reflection from the ‘wrong’ side of the glass, which may vary in opacity levels. At least there will be little detail and little contrast in the object being viewed. A thermal imaging camera will not be able to get accurate readings through glass (or other highly reflective surfaces).

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Do thermal cameras work underwater?

It is unlikely that thermal imaging will be effective underwater. There are several reasons for this, including issues with glass as outlined above.

Infrared waves are blocked by water in much the same way visible light is blocked by opaque barriers. Just as we cannot see through paint, infrared sensors cannot detect waves through the water due to the inability of the waves to pass through water easily.
The thermal conductivity and specific heat of water present another challenge for IR cameras. A one-degree increase or decrease in the temperature of water requires four times as much energy as in the air.

As a result, an object loses (or gains) heat energy much more quickly, and over shorter distances, compared to water. Objects submerged in water are therefore harder to distinguish from those in the air for thermal imaging purposes.

Can thermal imaging cameras see through walls?

Actually, no – but on the other hand, they don’t seem to see through anything. Thermal imaging cameras detect the surface temperature of the first object within their field of view; for example, point the camera at a wall or another solid surface, and it will record the heat emitted from the surface.

Exterior thermography rarely reveals much about what is going on inside and vice versa since most buildings are engineered and insulated to trap heat. In the case of a house fire, an IR camera would also be able to detect extreme heat radiating behind a wall since the wall would also heat up quickly.

In the same way, certain thermal cameras are sensitive enough to register a person’s body heat (up to +/- 0.01 Celsius). Imagine, for example, standing opposite the other side of a sufficiently thin and cold wall – provided the individual remains in place long enough for some of their body heat to transfer through the wall materials.

The fact that thermal imaging can save you money isn’t something you would expect from a device like this, but when you think about all it can do, you can see why it makes sense. Besides the initial purchase price, it is likely that this device will save your business or home thousands of dollars in potential maintenance and repair costs if faults, leaks, and weaknesses are not detected sooner.

You can also use thermal imaging for fun! A handheld thermal imager can be used for a variety of enjoyment-related tasks, such as identifying birds and other fauna when hiking or even comparing relative temperatures of drinks.

It is important to remember, however, that thermal imaging has many applications. At times, you will need to use additional tools and instruments to verify what you are seeing. As a result, you should keep this in mind when purchasing such devices.

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