Darkened streets, tops of buildings and open areas at night–once the bane of police forces–are no longer safe refuges for lawbreakers as increasing numbers of law-enforcement aviation units adopt infrared technology for covert criminal surveillance, tracking and subsequent capture. AIN recently visited FLIR Systems, one of the world’s leading infrared equipment developers and manufacturers, at its facility in Portland, Ore.

The company’s name derives from the acronym for forward-looking infrared–a description first coined in the early post-World War II era, when the technology was in its infancy and airborne systems were installed to look only at objects directly ahead of the aircraft. Today, FLIR Systems builds units whose gimballed infrared sensor “eyes” can be slewed to point at targets anywhere through 360 degrees around the aircraft, as well as above and below it.

Infrared radiation is continuously emitted by all objects, including humans, with the emission level being roughly proportional to the object’s temperature. But while invisible to the human eye, this radiation can be “seen” by an infrared sensor, which can differentiate temperatures down to fractions of a degree. And it can do this both by day or in the blackest of nights.

When portrayed on a screen in the cockpit, the resulting real-time thermal “picture” of a given scene, where warmer objects appear light and cooler objects appear darker, can be startlingly realistic and require little interpretation. A person hiding in an unlit alleyway, running across an open field at night or a stolen car racing down a freeway all show up clearly under infrared surveillance.

And even in broad daylight infrared can see things that the human eye cannot. An overflight of an apparently abandoned jungle airstrip in cocaine country might show nothing on a visual scan. But an infrared pass over the strip could detect the recent presence of an aircraft by the patch of cooler ground that had been in its shadow, with the shape of the patch approximating the aircraft’s silhouette and indicating its general shape, size and number of engines.

Individuals visually concealed by bushes and trees beside the strip would also show up clearly under infrared surveillance. Three years ago in San Antonio a released prisoner went on a shooting rampage, killing two police officers and injuring three others before fleeing into a densely wooded area from where, moving all the time, he randomly fired at passersby. An infrared-equipped police helicopter was called in and within eight minutes the individual was spotted and captured.

Typical of FLIR Systems’ law-enforcement products is its recently introduced Ultra 7500, a 26-pound, nine-inch-diameter, spherical unit containing the infrared sensor and a low-light-level TV camera. Normally installed under the aircraft, usually near the nose, the unit is operated by an observer via a multifunction handheld control. With it, the observer can alternate between infrared and the low-light camera, the latter having a very powerful zoom and autofocus feature that allows the aircraft to stay three or more miles away from suspicious activity while still monitoring it closely.

The unit can also be set to track an operator-designated target, after which its fiber-optic gyro stabilization system will automatically slew horizontally and vertically to keep the target centered in the display screen, regardless of the aircraft’s subsequent maneuvers in pitch and roll.

An optional system add-on, which has been selected by many law-enforcement agencies, is a long-range laser illuminator, whose pencil-thin beam can be pointed by the airborne observer at a fugitive.

More than 300 U.S. law-enforcement organizations are now flying with FLIR Systems’ infrared equipment, and a number of overseas police forces also do so.
But this is a fraction of the company’s total output of well over 30,000 systems in various configurations, most of which are in military land, sea and air use, including most recently the unmanned air vehicles flying reconnaissance patrols, which datalink their findings down to U.S. ground forces.