Thermal cameras detect temperature by recognizing and capturing different levels of infrared light. This light is invisible to the naked eye, but can be felt as heat if the intensity is high enough. ... Thermal cameras can see this radiation and convert it to an image that we can then see with our eyes.

How does a thermal imaging camera work?

All objects emit infrared energy, known as a heat signature. An infrared camera (also known as a thermal imager) detects and measures the infrared energy of objects. The camera converts that infrared data into an electronic image that shows the apparent surface temperature of the object being measured.

How far does thermal imaging work?

A typical application for thermal imaging is border security, where most threats occur at night. Watchtowers spaced at 4km intervals or more have to be able to detect threats at ranges up to 2km or more to guarantee full coverage of the border.