A 'laser-pointer' for detecting roadside bombs

Michigan State University researchers have developed a laser that could detect improvised explosive devices (IEDs) with an output comparable to a simple presentation pointer.

Michigan State University researchers have developed a highly sensitive laser that could detect improvised explosive devices (IEDs) from a safe distance.

Credit: Marcos Dantus

Credit: Marcos Dantus

Marcos Dantus, a chemistry professor at Michigan State leading the research, said that the detection of IEDs in the field is extremely important and challenging because the environment introduces a large number of chemical compounds that mask the select few molecules that one is trying to detect.

“Having molecular structure sensitivity is critical for identifying explosives and avoiding unnecessary evacuation of buildings and closing roads due to false alarms,” he said.

The laser, which has comparable output to a simple presentation pointer, works by combining ultra-short pulses that "kick" the molecules and make them vibrate, as well as long pulses that are used to “listen” and identify the different “chords.” The chords include different vibrational frequencies that uniquely identify every molecule, much like a fingerprint, according to a news release.

Funded in part by the Department of Homeland Security, the laser is paired with a type of powerful spectroscopy known as Coherent anti-Stokes Raman spectroscopy (CARS), which is detailed in a technical paper (PDF) published by the team in Applied Physics Letters.

The laser can work in tandem with cameras and allows users to scan questionable areas from a safe distance.

Another advantage is that it allows to detect IEDs in a manner that is nondestructive as IEDs can be found in populated urban areas. In these environments the laser can distinguish explosives from vast arrays of similar compounds. The MSU laser has been tuned to make these distinctions even for quantities as small as a fraction of a billionth of a gram.

“The laser and the method we’ve developed were originally intended for microscopes, but we were able to adapt and broaden its use to demonstrate its effectiveness for standoff detection of explosives,” said Dantus. He hopes to net additional funding to take this laser from the lab and into the field.

IEDs are homemade weapons that pose a constant threat to coalition soldiers in Iraq and Afghanistan, accounting for roughly 60 percent of deaths.


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