Nature Photonics article. . . . . Wired article

Two lasers at different frequencies aimed at the target together generate a plasma (basically excited, or ionised air). This plasma emits a florescence that is scattered in characteristic ways by the terahertz radiation of the material it hits. The reflection of the florescence is detectable from remote distances.

The researchers have tested hundreds of different substances and created a library of terahertz spectra to compare to the signal from the target and instantly identify the material that was hit.

The researchers demonstrated that they could detect the signal from 67 feet (20m) away, the length of their laboratory space, but theoretically they could identify materials hundreds of feet or even miles away, Liu said.


So is this the end of all privacy? It is now futile to attempt to conceal one's body with clothing? Will nude-o-scopes become ubiquitous in places like airports, casinos, and convenience stores? Can anyone ever again be certain that the gray smoked semiglobe on the ceiling only has a camera in it?
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