Someday in the future you may actually be able to breeze through airport security without the hassle of removing your shoes. Researchers at the U. S. Department of Energy's Argonne National Laboratory believe they know how to make that possible: by using a scanner using T-rays. The T-rays are said the be able with examine shoes without the passenger removing them. This form of electromagnetic radiation is believed to be harmless.

T-rays have been difficult to generate without using a host of bulky equipment. But researchers at Argonne have found a simple way to generate T-rays-terahertz radiation-using special, high-temperature superconducting crystals in a compact device.

"We developed a new source for terahertz radiation," Welp said. The work, done with researchers in Turkey and Japan, represents "a big step forward," he said.

T-rays are part of the electromagnetic spectrum that lies between microwaves on the low end and infrared radiation on the high end.

Unlike conventional X-rays, which can cause cell damage, T-rays do not have enough energy to alter cell ionization, which can lead to radiation sickness or cancer.

And while they cannot see through metals or water, they can penetrate many common materials like leather, fabric, cardboard, and paper.

"Terahertz radiation is sensitive to characteristics of a lot of chemicals," Welp said, offering the promise of new uses in airport scanners or detecting illicit chemicals or weapons that could not be picked up by an X-ray.

T-rays can also penetrate about four-tenths of an inch through human skin, offering some medical applications as well.