Back in December, there was a bit of a ray gun party at Yuma Proving Grounds, apparently. While the Air Force put its new Scorpion bomb-zapping microwave blaster through its paces, the Army Research Lab successfully tried out a prototype bomb-spotter that relies on lasers to spot explosives, according to Inside Defense.
[The Lab is] calling the system "Standoff LIBS," using the acronym for laser-induced breakdown spectroscopy...LIBS is a means of detecting traces of explosives on surfaces as far away as 30 meters, employing technology found in mining operations to determine the grade of ore.As envisioned, here is how the military system could work: A laser is directed at a vehicle or other item that could have a bomb attached. Due to the heat created by the laser, the surface material then vaporizes. In the process, the material's molecules break down into their atoms, which "get excited in the high-temperature environment and light up as sharp lights in the spectrometer" -- the device used to read and analyze the reaction, ARL research physicist Andrzej Miziolek explained.The wave length of the lights are then analyzed by a computer which matches the information against a library of known signatures...For instance, a laser pointed at the door handle of a car could let the system detect if someone who has touched explosives has subsequently touched that door...A typical application for the technology could be at a road checkpoint, where troops would be able to check cars for traces of explosives without the drivers' knowledge, a [military] official said."You don't want the adversary to know that you are checking him," the source said. "If you find explosives, you can go ahead and secure the situation."