The technology, described as "passive terahertz" screening, is one of several advances that the TSA and airlines hope will help U.S. airports handle the growing demand for air travel that is already creating bottlenecks and frustration at airports across the country.

The TSA has purchased several terahertz screening devices from Britain-based Thruvision to test in a TSA facility near Arlington, Va. If the devices pass the initial tests, they may be used on a trial basis at U.S. airports, said Kevin Gramer, vice president of Thruvision Americas.

The screening device, which is about the size of an old-fashioned PC computer tower and weighs about 50 pounds, reads the outline of people to reveal firearms and explosives hidden under their clothes.

The screening device, which is about the size of an old-fashioned PC computer tower and weighs about 50 pounds, reads the outline of people to reveal firearms and explosives hidden under their clothes.

Unlike the TSA's existing full-body scanners that bounce millimeter waves off of passengers to spot objects hidden under their clothes, Gramer said, the passive terahertz technology reads the energy emitted by a person, similar to thermal imaging used in night-vision goggles.