An Introduction to Thermal Imaging
I nfrared energy is emitted from all objects as heat. By detecting very subtle temperature differences of everything in view, infrared (or thermal imaging) technology is able to reveal what would otherwise be invisible to the naked eye. Even in challenging weather conditions or complete darkness, thermal imaging gives the user the ability to see the unseen. Thermal imaging was firstly developed for military use and has since been adopted by law enforcement personnel, search & rescue teams, security professionals and wildlife enthusiasts.
A Simplified Explanation of How Thermal Imaging Works
- The objects in the view all emit infrared energy (heat – invisible to the human eye).
- The Germanium lens focuses the heat on to the microbolometer (sensor).
- The signal processor converts the information in to a visible format that can be seen through the display screen.
What to look for in a Thermal Imager
When looking at purchasing a thermal imager there are a few essential factors that need to be taken into consideration to ensure you get a product which is best suited to your needs. We will now look at the key features that make up a thermal imaging device.
Of all the requirements sensor resolution is the most important factor to consider and when comparing products you should prioritise finding the highest resolution you can for your budget. Higher resolution imaging provides more accurate viewing and has a finer and sharper detail when used. Because of this it is one feature to not compromise on. Most specification sheets will state the detection (you can detect ‘something’ is present), recognition (you can recognise it is human) and identification (you can identify its a man/woman, model of car etc.) ranges of a man sized target with an emphasis on the detection range.
Range of detection:
The range of detection and consequently the recognition and identification ranges vary from model to model and therefore when deciding which unit is best it is essential you determine exactly what you will be using it for to ensure it is able to perform under the required conditions. Range of detection is determined by a combination of optical magnification and sensor resolution.
Also known as frames per second (FPS) or frame frequency, the frame rate determines the rate at which the imaging device produces consecutive images and therefore the refresh rate and smoothness of the moving image you can see. Most models specification will display the rate in Hz ranging from 9 to 50, a higher frame rate means a smoother image when panning or tracking a moving target. To help get an idea of what to compare this to a standard TV broadcast rate is 25Hz.
Taking your thermal out of the country
All thermal cameras with a frame rate above 9Hz – or weapon mounted (regardless of frame rate) – are strictly controlled by ITAR regulations and are subject to UK Government Export Licensing Regulations. A license will need to be obtained prior to export, even temporarily (e.g. holiday), from the UK. Some countries may be embargoed and no thermal imagers or night vision devices can be taken or exported to them. It is the responsibility of the exporter, whether it be a company or individual, to ensure that such license is obtained. Failure to comply is a criminal offense.
For further information visit – UK Government – Controlling defense, security and dual use strategic exports