Forward looking infrared
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A forward looking infrared (FLIR) is the North American English term for a camera that takes pictures using the infrared portion of the electromagnetic spectrum. Elsewhere in the English speaking world, these are typically called Thermal imagers. Often these contain sub-systems known as Thermal imaging common modules or TICM. FLIRs are often described as "infrared cameras". Since FLIRs use detection of thermal energy to create the "picture" assembled for the video output, they can be used to help pilots and drivers steer their vehicles at night, and in fog, or detect warm objects against a cold background when it is completely dark (such as a cloudy, moonless night). Note that a FLIR's wavelength range differs from a night vision camera, which detects wavelengths up to around 1-1.5 micrometres (slightly higher than the human eye can detect).
There are two basic ranges of infrared. 8-12 micrometre cameras (or "far infra-red" or LWIR) can see engine exhaust, or human body heat a few miles away, but longer distance viewing becomes blurred because the infra-red light is absorbed, scattered and refracted by the air.
3-5 micrometre infrared ("MWIR") cameras can see almost as well, and are far less absorbed by air, but generally require a much more expensive sensor array, and lower-temperature cooling.
Many FLIR systems use digital image processing to improve the image quality. FLIR sensor arrays often have inconsistent responses from pixel to pixel. To fix this, the response of each pixel is measured at the factory, and a transform, mostly linear, maps the measured brightness.
FLIRs are often used in naval vessels, fixed-wing aircraft, helicopters, and armored fighting vehicles. In warfare, they have three large advantages. First, the imager itself is difficult for the enemy to detect. Second, they see heat, which is hard to camouflage. Thirdly, FLIR systems can see through smoke, fog, haze, and other atmospheric obscurants better than a visible light camera can. However, it is hard to distinguish friend from foe when using the FLIR, which has led to friendly fire incidents.
Forward Looking InfraRed (FLIR) systems is not the name of an infrared camera, but is a company that manufacturers infrared devices.
[edit] Citizen Privacy and FLIR
Whether or not the need and the duty to protect citizens from danger outweighs the right to privacy, and whether individuals, if given the choice would urge the government to buy more FLIRs is a topic of some debate. [1] [2] [3]
[edit] The Many Uses of FLIR
In addition to its potential for surveillance of known or suspected criminals, FLIR can be used for watershed temperature monitoring and for monitoring wild game habitats.
