Scientists say optical cloaking is near

Champaign, Ill. -- Two U.S. scientists say they have developed a technique using computer simulations that results in the nearly total cloaking of an object.

University of Illinois Professor Harley Johnson and postdoctoral researcher Dong Xiao noted cloaking of microwave energy was reported in 2006 by researchers from Duke University, Imperial College London and the Sensor Metrix Corp. in San Diego. That was achieved using metallic structures called ring resonators. But since metallic particles absorb some visible light, the resonators failed to fully cloak energy in the portion of the spectrum visible to humans.

To overcome that problem, Xiao used resonators made with a coating of silicon crystals to cloak a container.

"When light of the correct wavelength strikes the coating, the light bends around the container and continues on its way, like water flowing around a rock," Xiao said. "An observer sees what is behind the container, as though it isn't there. Both the container and its contents are invisible."

The scientists admit their cloaking technique isn't yet perfect, and Xiao said, "We refer to the technique as 'approximate' cloaking.'"

Xiao and Johnson's work is highlighted in the June issue of the Materials Research Society Bulletin.

Copyright 2008 by United Press International.