Editing Forward-looking infrared (section)

== Design ==
[[File:Flickr - Official U.S. Navy Imagery - Alleged drug traffickers are arrested by Colombian naval forces..jpg|thumb|300px|FLIR imagery from a U.S. Navy helicopter: Alleged drug traffickers are being arrested by Colombian naval forces.]]

[[infrared|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&nbsp;μm and can see heat sources, such as hot engine parts or human [[body heat]], several kilometers away. Longer-distance viewing is made more difficult with LWIR because the infrared light is [[absorption (optics)|absorbed]], [[scattering|scattered]], and [[refraction|refracted]] by air and by water vapor.

Some long-wave cameras require their detector to be [[cryogenics|cryogenically]] cooled, typically for several minutes before use, although some moderately sensitive infrared cameras do not require this. Many thermal imagers, including some forward-looking infrared cameras (such as some LWIR [[Synthetic vision system|enhanced vision systems]] (EVS)) are also uncooled.

''Medium-wave'' (MWIR) cameras operate in the 3–5&nbsp;μm range. These can see almost as well, since those frequencies are less affected by water-vapor absorption, but generally require a more expensive [[sensor array]], along with cryogenic cooling.

Many camera systems use [[digital image processing]] to improve the image quality. Infrared imaging sensor arrays often have wildly inconsistent sensitivities from [[pixel]] to pixel, due to limitations in the manufacturing process. To remedy this, the response of each pixel is measured at the factory, and a transform, most often linear, maps the measured input signal to an output level.

Some companies offer advanced "fusion" technologies that blend a visible-spectrum image with an infrared-spectrum image to produce better results than a single-spectrum image alone.<ref>{{cite web |url=http://www.sri.com/newsroom/videos/topic/273 |title=Three-Band Video Fusion Demo : Sarnoff Corporation |date=May 2008 |publisher=Sarnoff.com |access-date=2011-11-24}}</ref>