How FLIR Imaging Works

An image of the thermal spectrum through FLIR imaging

The word FLIR is a US Military Acronym that officially stands for Forward Looking Infrared Radar although in common usage it has generally been changed to Forward Looking InfraRed. The term originated with airborne thermal imaging units that were angled to look forward. It has since been in public knowledge as meaning any thermal infrared imaging camera that is used. There is even a major manufacturer in the industry that borrowed the acronym. They are known as FLIR Systems Inc. and they manufacture every type of infrared camera there is.

FLIR imaging is a night vision technology used in operation desert storm war and now being used currently in  operation desert fox  in the Persian gulf.  Thermal imaging is used not only for surveillance but for target acquisition and tracking.
Helicopters (apache) have forward looking infrared units mounted on them that can give the pilot a thermal picture miles ahead of the aircraft.  Fighter planes (F-16, F-14, F-15, F-18, stealth fighter, tomcat, etc.) use thermal infrared imaging to locate and control fire to specific targets.  Even some of the missiles being fired at the Iraqi’s are guided with infrared technology ( heat seeking missile ).

Thermal energy is transmitted in the infrared wavelength ( 1 micron to 100 microns ).  You can see by the image above that thermal energy is closely related to visible light in that it travels in a wave.  Thermal ir imaging takes traditional light amplification night vision devices ( the green images you see on TV) one step farther.  The human eye can only see the narrow middle band of visible light that encompasses all the colors of light in the rainbow.
Thermal infrared imagers translate the energy transmitted in the infrared wavelength into data that can be processed into a visible light spectrum video display.  Visible light is dependent on a light source ( the sun or artificial ) reflecting off an object to be received by our eyes.

Remember, all objects above 0 degrees Kelvin emit thermal infrared energy so thermal imagers can passively  see all objects regardless of ambient light.  This can give you an enormous advantage on the battle field, especially in the persian gulf wars (operation desert storm and operation desert fox).    Advances in stealth technology have not only concentrated on creating battle field machines that are hard to see with radar,  but they have also drastically reduced the thermal infra red   signature.  This signature is what allows thermally guided missiles to home in on there targets.  The thermal infrared heat signature also allows ground and air forces to track enemy movement of large resources (tanks, planes, vehicles, etc.).  Today’s battle field machines have reduced the thermal signature   ( mainly by cooling the exhaust and insulating the heat producing parts ) to a level that is much harder to detect.  But they are not invisible!  With thermal infrared imagers military hardware, transport vehicles, machines and humans stick vastly.  You can defeat traditional night vision device but you simply cannot hide completely from thermal infrared imaging technology.  Not even Saddam Huisein can hide.

FLIR imaging cameras come in different configurations to suit your specific need.  Tanks like the M1A1 Abrams main battle tank have driving systems that rely on thermal infra red imaging to navigate any terrain day or night.  That is one of the benefits of thermal infrared imaging technology it can be used in daylight or complete darkness, it is totally independent of visible light.   Consumer versions of this driving system can be found in products like the night sight thermal infrared vehicle imager.  This roof mounted vehicle option offers pan, tilt, and remote joystick control for mobile applications.  Ground forces are issued small pocket sized thermal infrared imagers ( like the milcam le ) for short to medium range surveillance and reconnaissance.  Snipers are furnished with thermal infrared imaging weapon sights which can acquire and remove living targets from considerable distances.

This page is very short for such a technical topic and is not meant to be a definitive resource but a very general outline.  At SPI we welcome any questions or comments you might have regarding FLIR imaging technologies.  Please call Jim Santana at (702) 369-3966 in the Las Vegas area, toll free at (800) 403-2983, or email us with your questions and you will be responded to immediately.

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