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What is thermal imaging?


No matter how many carrots we eat, our human eyes are pretty poor at seeing in the dark. This is where thermal imaging can help. Thermal imaging is the process of detecting infrared radiation and producing an image of that radiation (a thermogram).

To produce a thermogram you need a thermal imaging camera, also known as an infrared camera. When we think of infrared cameras, probably the first thing that comes to mind is finding people in the dark, whether that’s rescuing someone in a disaster situation or catching a criminal on the run.

However, these cameras have a wide variety of applications in industry, energy, building, science, automation and more. For example, you could use cameras like the TI160 and TI384 from ULIRvision to detect overheating in a power line.

At the other end of the scale, you could use the TI120, also from ULIRvision, to detect the possible presence of pandemic viruses such as SARS in a crowd of people moving through an airport. We’ll be discussing these different uses in more detail in another blog.

So how does thermal imaging work?

Whereas normal cameras work with visible light, (i.e. the light that we can see with our own eyes) thermal imaging cameras use infrared light (which we can’t see). The thermal imager converts this infrared radiation into electrical signals, making it visible to us as a thermogram.

Infrared radiation is generated when molecules move. For molecules to move, their temperature has to be above absolute zero – this is very, very cold −273.15° Celsius to be precise. The higher the temperature, the more the molecules inside an object move, generating more infrared radiation. So although our eyes can’t see infrared light we can feel it as heat.

As warm-blooded creatures, we humans generate quite a bit of infrared radiation, making us easy to spot with an infrared camera compared to other objects in our surrounding environment.

These variations in infrared emissions / temperature show up on a thermogram as different colours, as you can see in the images on this page and the video below.