Forward looking infrared

Forward looking infrared (FLIR) cameras, typically used on military and civilian aircraft, use a thermographic camera that senses infrared radiation.

The sensors installed in forward-looking infrared cameras—as well as those of other thermal imaging cameras—use detection of infrared radiation, typically emitted from a heat source (thermal radiation), to create a "picture" assembled for video output.

They can be used to help pilots and drivers steer their vehicles at night and in fog, or to detect warm objects against a cooler background. The wavelength of infrared that thermal imaging cameras detect differs significantly from that of night vision, which operates in the visible light and near-infrared ranges (0.4 to 1.0 μm).

Design

Infrared light falls into two basic ranges: long-wave and medium-wave. Long-wave infrared (LWIR) cameras, sometimes called "far infrared", operate at 8 to 12 μm, and can see heat sources, such as hot engine parts or human body heat, a few miles away. Longer-distance viewing is made more difficult with LWIR because the infrared light is absorbed, scattered, and refracted by air and by water vapor.