Laser detection has long been a way for military units to determine if something hazardous - be it emissions or explosives - lie ahead. Now, a new "air laser" developed by Princeton University may make this process not only more accurate but safer as well.
Standard LIDAR detectors work by focusing a laser beam on a distant object and then measuring the scattering of the returning laser beam against the original. While this will tell observers if something odd is going on in and around the area where the laser beam was focused, it cannot tell them exactly what or in what concentrations.
Now, Princeton University scientists in conjunction with the Office of Naval Research have created the Air Laser, which is intended to be a far more accurate tool in finding out not only that something is "over there", but exactly what it is and how much of it is present.
Instead of relying on reflected beams, the Air Laser focuses on a tiny cylinder of air (1mm long) in the area of the target object. The UV laser then excites the oxygen atoms in the cylinder, which emit infrared light when the UV pulse ends. This light travels along the cylinder, exiting more atoms and producing a coherent laser beam that is sent directly back to the original UV source. Not only does this beam contain traces of just what is present in the area sampled, but the returning beam is thousands of times stronger than in standard LIDAR methods, and this should allow for a far better ability to detect even the minuscule amount of gas some IEDs and other chemical agents produce.
Right now, the team is working on perfecting the Air Laser's core technology and extending its range past its current one and one half feet. Fortunately, the beam should simply be able to focus a target farther away and natural excitation processes should take care of the rest.
In a world increasingly besieged by "undetectable" bombs and noxious agents, developing a smart, sensitive way to detect them is certainly not just a bunch of hot air.