Lasers!

More fuel for my all-seeing laser detector of the future:
http://spectrum.ieee.org/semiconductors/optoelectronics/using-lasers-to-find-land-mines-and-ieds/0
This article solves the problem of detecting gaseous chemicals. Apparently the lasing creates an area that reflects radar pulses when the target chemical is present.

And the original that got me thinking:
http://gizmodo.com/5923980/the-secret-government-laser-that-instantly-knows-everything-about-you


-JD