How waves can help scan objects behind barriers

​New York: A group of researchers has created a special type of strong electromagnetic wave that can help authorities see objects behind barriers.

In a new research at the University of Rochester, New York, researchers Kang Liu, a Ph.D. student in optics, Xi-Cheng Zhang, the Director of the Institute of Optics, and a group from Greece led by Tzortzakis Stelios worked with this special electromagnetic wave --called terahertz (THz).

The team demonstrated that they could detect a THz wave at a distance of up to 100 feet. "The use of an unconventional laser beam in our project goes beyond a scientific curiosity.

It makes possible the remote sensing of chemical, biological and explosive materials from a standoff distance," Zhang was quoted as saying.

THz waves, which fall between microwave and the infrared band on the electromagnetic spectrum, can penetrate certain solid objects that are opaque to visible light to create images of what is hidden from view.

These waves do not damage human tissue but they can be absorbed by water molecules in the air and weaken significantly over longer distances.

So to weed out this obstacle, the team created a wave more than five times stronger than what is generated by more conventional means.

The key to their results, published in the journal Optica, was the use of a specific exotic laser beam -- called a ring-Airy beam -- to generate a THz wave that has 5.3 times the pulse energy of THz waves created with standard Gaussian beams.

"We believe our method could help THz remote sensing from more than 100 feet away by providing a more robust and flexible way to generate THz remotely," said Liu.