How does thermal imaging work?
Thermal imaging cameras detect heat, whereas normal digital cameras have sensors which detect light.  On a thermal imaging camera, a special lens focuses the heat (infrared energy) given off by an object onto a detector which is sensitive to heat.  Therefore thermal imaging will work both in daylight as well as in complete darkness as it is unaffected by light.

Can thermal imaging see through objects/does it work like X-Ray Vision?
No – because thermal imaging only detects heat, it will not ‘see’ through solid objects, clothing, brick walls, etc.  It will see the heat coming off the surface of an object.  In fact, thermal imaging technology cannot see through glass, either.  Because of this, the lenses on thermal imaging cameras have to be made of a special element (Germanium) and not from glass.  This makes the lenses of thermal imaging cameras more expensive than regular camera lenses.  Contrary to popular belief, thermal imaging cannot really see through somebody’s clothing.

How far can thermal imaging cameras see?
This depends on a number of factors:

  1. How large and how hot the object is you are looking at
  2. The size (resolution) of the detector in the thermal imager
  3. The pixel pitch of the detector (how far apart each pixel is on the detector – this is measured in microns – the closer together they are, the higher the thermal image quality)
  4. The type/size of lens being used on the thermal imaging camera
  5. The weather conditions

To give a rough idea:  A Thermoteknix TiCAM 750MR (Medium Range) Thermal Imaging Binocular with a 75mm lens and a 384 x 288 resolution detector with a 17µ pitch can detect a man at 2km in standard weather conditions.

What is thermal imaging useful for?

Energy Efficiency
For example, thermal imaging can be used to see how much heat is escaping from a house/building and to check how well insulated that building is or to monitor water ingress in buildings (dampness shows up as cold on brickwork/plaster/flooring, etc).

Police and Law Enforcement
For example, to see fugitives hiding in darkness or under the cover of trees, to see if a car is warm which would suggest it had been driven recently, to follow vehicles at night (e.g. from a helicopter).  Thermal Imaging can detect such slight difference in temperatures that it can even see, for example, the heat left by skid marks from a recently departed vehicle.  Police also use thermal imagers to look at houses where it is suspected that a cannabis farm is operating as they tend to give off more heat than neighbouring buildings – especially from the roof generally.  Small differences in temperature can indicate hidden compartments in walls and my show if somebody is concealing a weapon or gun under their clothing.

To find people/bodies lying injured in remote or other areas/burning buildings/natural disaster zones such as earthquakes/floods.  Thermal Imaging will also see through fog/smoke.  It is also used for detecting forest fires.

Surveillance/Reconnaissance/Border Control
To see movement/presence of people/vehicles.  It is also widely used in maritime environments for the same purpose.

For monitoring hotspots in electrical equipment (Predictive Maintenance) and for monitoring high temperature processes such as in boilers, furnaces/kilns.  Thermal Imaging is routinely used in the monitoring of cement kilns.

For seeing in the darkness for combat environments and for general situational awareness.

For seeing differences in body temperature – inflammation in the body of a mammal creates extra localized heat which is visible/detectable by a thermal imaging camera.

Thermal imaging is used in so many applications in this area that it is almost impossible to list them all.  However, F1 and Indycar racing teams use thermal imaging cameras to monitor the heat of the tyres on their cars to optimize traction, to track the heat signature of missiles, to film lions hunting at night and NASA even used Thermoteknix thermal imaging cameras to look for water on the moon (and they found it!).

What is the difference between Night Vision and Thermal Imaging?
Night Vision (also known as I2 or Image Intensification) relies on at least a very low level of light (less than the human eye can detect) in order to amplify it so that it can produce a picture.  Night Vision will not work in complete darkness whereas thermal imaging will because it only ‘sees’ heat.
To summarise, Night Vision is good for identification purposes, can see through glass but cannot see in complete darkness.  Thermal Imaging cannot see through glass, but can see in complete darkness, it is therefore a more powerful detection technology, cannot be blinded by light and can see through fog and smoke.  Combine the two technologies into Fused Night Vision with, for example, a Thermoteknix ClipIR Thermal Imager Clip On device and you have the best of both worlds.