Scientists have come up with a new technology to detect a chemical sample located one kilometer away. In future, this could play a powerful tool for the military to detect explosives located at a distance and even for astronomers to probe alien worlds for life. Vladislav Yakovlev, a biomedical engineer at Texas A&M University and a co-author of the study said that previous research have described similar laser sensing technologies but no one has been successful to obtain such long distances, and especially not on a single-shot basis.
The technique makes use of a physical phenomenon called “Raman scattering”. When light passes through a particle, the particle’s molecules scatter a small fraction of the incoming photons around, changing the photon’s energy level in the process. This causes a color change in a small percentage of the laser pulses that hit the target. “The color change of the light is unique to the specific chemical,” Yakovlev explained, “so we then detect the color of the light and that allows us to identify the specific chemical.” This led the scientists to differentiate similar-looking powders like ammonium nitrate and sodium nitrate — both of which can be used to make bombs — from 400 meters (0.2 miles) away.
The estimated cost for the entire setup is around $30,000. To make the system more “real-world friendly”, the researchers have to identify which conditions are ideal for irradiation in addition to making sure that the device can identify compounds as accurately as it can detect individual chemicals. And it’s reasonably safe, the researchers say, the only threat is the effect that the laser might have on human eyes – something that operators can avoid by following eye precautions.
“Remote detection of explosives is a really big thing,” Yakolvev said. “Our hope is that this technique will allow for the detection of hazardous chemicals from a safe distance in real time.”
“Considering that it takes just one laser shot to quantify the presence of specific compounds on a ground,” Yakovlev said, “one can imagine mapping the large area quickly identifying locating and quantifying the presence of such compounds” from the comfort of a plane’s cockpit. It could even be used in future space missions to Mars, he said. “You can imagine putting such remote sensing system on a satellite, and probing each spot on the ground” for signs of life on other planets.
Via : theverge
Source : pnas