In Brief

Millimeter Waves for Weapons Detection

Millimeter wave technology from Smiths Detection, Brijot and QinetiQ

By Derek Slater

January 01, 2006 — CSO —

Weapons Detection Turns out your body emanates millimeter waves. (It always has. Don't get embarrassed about it now.) Millimeter waves, a form of radiant energy, have a wavelength bigger than microwaves but smaller than infrared. At the fall ASIS show in Orlando, two companies showcased products that use millimeter wave technology to tell if you're carrying a concealed weapon: Brijot Imaging Systems and Smiths Detection. (U.K.-based QinetiQ also makes one.)

Unlike your body, weapons and other high-density materials don't give off many millimeter waves. So when these products scan a person, they look for blank spots in the scanned image, areas of the body that should be giving off millimeter waves, but aren't.

Smiths Detection's product is a large chamber called Tadar that looks at home in an airport checkpoint. Brijot's BIS-WDS Prime camera units are portable, so they can conceivably be can be set up temporarily for special events. Both systems have limits; neither can see "through" the scanned person to detect a weapon, so you either need multiple cameras to get a whole-body view, or you need to have a person being scanned to pirouette slowly in front of the unit.

Millimeter wave technology has been evolving toward the mainstream for years; it's partially the basis for what author Jeffrey Rosen called the "Naked Machine," an airport passenger scanning device that detractors find invasive because of the detailed image it displays. The Naked Machine uses active scanning, bathing subjects in millimeter and microwaves. The Brijot and Smiths products use passive scanning instead (though the Tadar system can use active scanning). Passive scanners simply read the waves already given off by the "scanee."

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