U.S. engineers turn to sound to detect hidden explosives

NASHVILLE, Oct. 24 (UPI) -- U.S. engineers say an acoustic detection system to identify homemade bombs can detect the difference between low-yield and high-yield explosives.

That capability has never before been included in a remote bomb detection system, engineers at Vanderbilt University said.


Current techniques for explosives detection range from dogs to mass spectrometry, gas chromatography and specially designed X-ray machines.

"Existing methods require you to get quite close to the suspicious object," civil and environmental engineering Professor Douglas Adams said. "The idea behind our project is to develop a system that will work from a distance to provide an additional degree of safety."

Adams is developing the acoustic detection system with colleagues at Purdue University and the Colorado School of Mines under a grant from the Office of Naval Research.

In the new system a phased acoustic array focuses an intense sonic beam at a suspected improvised explosive device while an instrument called a laser vibrometer is aimed at the object's package and records how it is vibrating in response.

"We are applying techniques of laser vibrometry that have been developed for non-destructive inspection of materials and structures to the problem of bomb detection and they are working quite well," Adams said.

The best way to detect the contents of devices made of rigid material like metal is to use short ultrasonic waves, the researchers found, while longer subsonic and infrasonic waves were effective in penetrating softer materials like plastics.

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