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What is Thermal Scanning?

Infared, thermal imaging, thermal scanning, thermography,

March 30 , 2021

Thermal scanning is the use of a special type of scanner (camera like device) that is able to detect infrared radiation.  Normally humans are unable to see into the infrared spectrum and instead have a very narrow field of vision as shown below.  However, with special equipment we are able to detect and convert this infrared data into a visual image.

Infared Spectrum and visible specturm
The visible spectrum and IR spectrum

What is so special about infrared? 

Infrared radiation has a very special quality, such that everything that is above absolute 0 (-273.13°C or 0°K) gives off infrared radiation that is directly proportional to its energy, in turn this can be converted to temperature.  Thus through understanding what temperature correlates to what ‘colour’ of the infrared spectrum, we are able to accurately calculate and deduce temperatures.  This process in itself may seem simple when seeing images like those below.  

Thermal image of Thermal Scanners car, in rainbow spectrum.
Thermal image of Thermal Scanners car, in rainbow spectrum.

However, to get these temperatures accurate is a different story, as any trained professional can tell you.  That’s because every material actually gives off slightly different levels of radiation depending on something called the materials ‘emissivity’. The topic of emissivity will be explored in detail in another blog due to its complex nature.

So what can thermal scanning detect?

Well due to the way that thermal scanning works it can detect problems that involve heat that can’t be seen with the naked eye.  Problems like these actually appear more often than many realise, such as in electrical equipment, solar panels and energy leakage.  

In electrical equipment, components tend to heat up to high levels before failure.  Depending upon the component some of them can reach temperatures in excess of 400°C before failure which can create high risks of electrical fire.

Thermal Scan of an Aeroplane taking off.

So what does thermal scanning actually detect?

Thermal scanning can only detect the surface energy of an object. As such most of what you see on movies or tv with thermal scanning actually isn’t possible.  Thermal scanning can’t see through any solid objects such as walls or clothing, nor can it even see through glass or perspex!  This is because the thermal scanners only pick up the surface temperature of the object.