If those new airport X-ray scanners offend your modest sensibilities, you may not want to read this. A new terahertz remote sensor may soon be able to see through walls, packaging materials, and even clothing from thousands of feet away, identifying materials contained inside through their unique spectral signatures.

 

Terahertz waves exist in the part of the spectrum between infrared and microwave light, but they were largely thought to be a dead end for remote sensing tech because they are absorbed and degraded by moisture in the air, making them highly unreliable at distances beyond just a few inches.

 

But researchers at Rensselaer Polytechnic Institute decided that if terahertz waves themselves won’t work across distances, they would use a laser to excite terahertz radiation at faraway targets. The detector works by zeroing two lasers at different frequencies on a target. This causes the materials the laser hits to emit terahertz radiation, which in turn emits a fluorescence that is unique to that material as well as detectable from far away.