How does a thermal camera work?

Any object with a temperature above absolute zero (minus 273.15 degrees Celsius) is going to emit radiation because all the molecules that make it up are in motion – and the more the motion, the more the radiation emitted.

What a thermal camera does, then, is create an image of an object based on the radiation it emits.

Thermal Camera Survey

A thermal camera being operated by an engineer.

Some – but certainly not all – of that radiation is visible. Only about half the energy given off by the sun is visible, for example. The rest is either ultraviolet or infrared, depending on the wavelength of that radiation.

And infrared radiation is what a thermal camera picks up on and uses to create an image.

Image from Thermal Imaging Camera

An image captured with a thermal imaging camera.

How does it do that?

In a normal digital camera, the lens focuses what it sees onto a detector chip made up of millions of pixels, each analysing the colour of the light that falls onto it before sending that information to be processed within the camera to create a visual image.

In a thermal camera, though, that detector chip (a microbolometer) is a sensor array with a grid usually made up of only thousands of pixels. Each of those pixels changes its electrical resistance depending on the intensity of long-wavelength infrared radiation the lens directs onto it.

Detector chips in thermal cameras can either be cooled or uncooled. Handheld cameras tend to contain uncooled chips, and can normally distinguish temperature changes of 0.4 degrees Fahrenheit (0.2 degrees Celsius).

Cooled detectors, on the other hand, are bulkier – and considerably more expensive – but can detect much more subtle temperature changes, and at far greater distances.

However, no thermal camera can take give accurate readings without adjustments to compensate for the reflectivity and the emissivity of the surface you’re looking at.

And there are other aspects of thermal imaging you definitely need to have under your belt to make a success of a career in thermography.

These include the correct setup of your camera in the first place, accurate analysis of the information it provides and the ability to communicate that analysis effectively to your client in order to solve their original problem.

That could be something as small as an overheating electrical component on a circuit board, or as large as massive heat loss from a tower block – each requiring a different approach.

And after taking any of the many specialist thermal imaging courses available from the iRed Academy, you’ll know exactly how to approach a client’s problem situation, how to set up your thermal imaging equipment to produce the right kind of image, how to analyse the image produced and how to explain that analysis in order to provide your client with an effective solution.

Talk to us about the kind of thermography career you’re interested in, and we’ll help get you started, get trained, and get qualified.