Now you see it, now you don't: invisibility cloak nears reality

Thu Sep 17, 2015 9:04pm EDT
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By Will Dunham

WASHINGTON (Reuters) - A cloak of invisibility may be common in science fiction but it is not so easy in the real world. New research suggests such a device may be moving closer to reality.

Scientists said on Thursday they have successfully tested an ultra-thin invisibility cloak made of microscopic rectangular gold blocks that, like skin, conform to the shape of an object and can render it undetectable with visible light.

The researchers said while their experiments involved cloaking a miniscule object they believe the technology could be made to conceal larger objects, with military and other possible applications.

The cloak, 80 nanometers in thickness, was wrapped around a three-dimensional object shaped with bumps and dents. The cloak's surface rerouted light waves scattered from the object to make it invisible to optical detection.

It may take five to 10 years to make the technology practical to use, according to Xiang Zhang, director of the Materials Sciences Division of the U.S. Department of Energy's Lawrence Berkeley National Laboratory and a professor at the University of California, Berkeley.

"We do not see fundamental roadblocks. But much more work needs to be done," said Zhang, whose research was published in the journal Science.

The technology involves so-called metamaterials, which possess properties not present in nature. Their surfaces bear features much smaller than the size of a wavelength of light. They redirect incoming light waves, shifting them away from the object being cloaked.

The cloaking "skin" boasts microscopic light-scattering antennae that make light bouncing off an object look as if it were reflected by a flat mirror, rendering the object invisible.   Continued...

Light reflects off the cloak (red arrows) as if it were reflecting off a flat mirror in this 3D illustration of a metasurface skin cloak made from an ultrathin layer of nanoantennas (gold blocks) covering an arbitrarily shaped object is shown in this handout image courtesy of Xiang Zhang group on September 17, 2015. REUTERS/Xiang Zhang group/Lawrence Berkeley National Laboratory/Handout