Frisking From Afar

Millimeter-wave camera picks up both metallic and plastic concealed handguns.

#### Tech Update Archive

DEERFIELD, MA-Between microwave and infrared lies the millimeter wave band. This little-heralded portion of the electromagnetic spectrum turns out to be perfect for "remote frisking." Millitech Corp. has designed a camera to accomplish just that. The idea calls for measuring the time delay and intensity of millimeter wave energy that radiates naturally. At millimeter wavelengths, people are good emitters, while metals are very poor. Dielectric objects, such as plastics, ceramics and powdered drugs, are somewhere in between. Clothing and building materials, such as wallboard, are virtually transparent.