New airport screeners could save time, energy

/ Source: Discovery Channel

Using several new advances in T-rays, or terahertz radiation, airport scanners could soon determine if a vial of white powder in a suitcase is common sugar or illegal drugs.

Scientists at the Massachusetts Institute of Technology, at Rice University, in Europe and elsewhere have independently undertaken research to make it dramatically easier and cheaper to produce, amplify and direct T-rays.

Their work could eventually eliminate the need for long airport security lines and bulky X-ray machines while detecting more narcotics and explosives.

"(With T-rays) you can see through optically opaque materials, and many biochemical compounds, like explosives, have a signal in the terahertz range," said Qing Hu, a scientist at MIT who developed a new high powered quantum cascade T-ray laser.

For security officials, T-rays offer two key advantages over X-rays. First, T-rays pass through clothing but not skin, making it easier to find concealed weapons without the harmful ionizing radiation that results from X-rays.

T-rays are even sensitive enough to even pass through a sealed envelope to read the message inside.

More importantly, narcotics and explosives absorb T-rays. By shining a variety of T-rays on an airline passenger and measuring which wavelengths are absorbed and which ones bounce back, airline screeners could find hidden drugs or trace amounts of an explosive.

"All explosives have these fingerprints in the electromagnetic spectrum," said Hu. "They can be quite distinctive."

The three independent research teams have gone a long way toward creating the powerful and energy efficient T-rays scientists and security officials need.

First, MIT scientists have produced a powerful and tunable terahertz laser. Their research is detailed in the journal Nature Photonics.

Once the T-ray is created, it can now be amplified. Known as gain switching, the technique basically jumpstarts the T-ray. The laser takes fractions of a second to reach full power. If, however, a laser being charged is hit by another, full strength laser, then the two lasers emerge more powerful than either one.

The effect is similar to two people jumping on a trampoline. If one person hits the other person's bounce, they can suddenly bounce much higher. In the new system, also described in Nature Photonics, the emerging T-ray is 400 times more powerful than it was before.

Scientists can now also send those powerful T-rays in any direction, using new technology developed by Rice University researchers, which allows scientists to reflect and scatter the T-rays in any direction they desire.

Junichiro Kono, a professor at Rice University, finds such developments "promising for the future of T-ray technology."

Reading letters without opening them, finding drugs and identifying terrorists could all be possible with efficient and powerful terahertz lasers.