Military infrared sensor that ferrets out suicide vests offered to local law enforcement.

• Position: Homeland Security News

* A sensor used in battle zones that can detect explosives and weapons hidden under clothing at long distances is now being marketed domestically.

Thermal Matrix USA sees its Access Counter IED Technology system as one answer to the long-standing problem of how to detect a suicide bomber before he reaches a secure area.

The product originated in 2005 as a "system of systems" that used long-, mid- and short-wave infrared, millimeter wave, terahertz and ultraviolet spectrums to create a complete picture of what subjects were concealing underneath their clothes. The Department of Homeland Security ran operational tests of the system, called the Gauntlet, and it worked well, but it was not portable, and took a long time to set up, said Bill Reinpoldt, the company's director of technology.

"It took a few guys and truck or two to move the system around. It was big and unwieldy," he said.

The company decided that the three infrared waves were doing the bulk of the work. The other spectrums were adding value but contributing to the complexity. It scrapped the others and stuck with a highly sensitive infrared device.

Meanwhile, privacy concerns emerged about the millimeter wave technology, which exposes human anatomy in the view screens. Also, infrared does not project any radiation like some of the Transportation Security Administration screening devices at airports, he added.

Infrared does not see through clothing. Bodies give off heat signatures, and any object between the skin and the sensor absorbs that heat. The concealed object casts a "shadow," which shows up on the monitor in fine detail. These objects might be...