Approximately sixty percent of coalition soldier deaths in Iraq and Afghanistan are due to improvised explosive devices (IEDs), placed along the roads. Because these bombs are often planted in public areas, it is important to detect them in a way that doesn't harm the surrounding infrastructure, or unnecessarily require civilians to evacuate nearby buildings. Researchers from Michigan State University believe that a laser-based system that they developed could fit the bill.
The laser itself is similar in output to a simple presentation pointer. Used in conjunction with a camera, it would direct both short and long pulses of light at suspicious objects or areas. The short molecules cause the molecules of explosive substances to vibrate, while the longer pulses are used to "read" those vibrations, which are unique to each explosive substance.
One of the challenges of field detection of explosives is the fact that there are so many similar chemical compounds present in the environment, and they can mask the sought-after molecules. Using the laser system, however, even a billionth of a gram of explosives can reportedly be detected.