In certain situations, security is of the utmost importance, but some security technologies present risks of their own. That is why researchers are working on new techniques to detect threats. Now those at the National Institute of Standards and Technology have developed a prototype system that can detect hidden weapons and threats up to 28 meters away.
This system is actually based on a camera design used in advanced telescopes. It utilizes superconductors that change in resistance when exposed to very faint light. In this case the light has to have a frequency around 850 micrometers, which is a terahertz frequency. Terahertz radiation has the ability to pass through clothing, but presents no threat the living tissue, which should make it very useful in sensing technologies. The system is also passive, so instead of requiring a dedicated terahertz source, it is able to image targets with only naturally occurring light.
The prototype's 251 sensors have the ability to resolve details as small as one centimeter, but operates at only six frames per second, which is a bit slow. Further development though could quadruple the number of sensors, which will increase the area it can image and the framerate.
Source: NIST via EurekAlert!