"Conventional security systems include metal detectors for personnel and x-ray systems for hand-carried items. To detect plastic or ceramic handguns and knives, plastic weapons, and liquid explosives, conventional metal detectors and x-ray systems can be augmented with millimeter-wave imaging that penetrates clothing but is reflected by the body and concealed items. Such a system, now in prototype stage, has been developed by David Sheen, Douglas McMakin, and Thomas Hall of the Pacific Northwest National Laboratory (PNNL; Richland, WA).

Consisting of a vertical millimeter-wave array of antennas scanned in a cylindrical manner about the person under surveillance, images from the system reveal differences in shape and reflectivity and allow operators to readily identify concealed weapons. In operation, the person scanned stands on a platform near the center of the scanner and is illuminated by a wide-bandwidth, diverging-beam coherent millimeter-wave source."

Click HERE to read the entire article from a 2001 edition of Visual System Deisgn Magazine. While controversial, the product has since become standard for screening at airports to ensure safety as dictated by Homeland Security.