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Scientists Engineer Material That Bends Light


For years, science fiction writers have imagined cloaking devices that could make objects or people invisible. While invisibility cloaks are still a fantasy, scientists have developed the optical materials that could some day make the illusion a reality. As VOA's Jessica Berman reports the materials, which bend light, have more serious applications as well.

Scientists have developed materials that can reverse the direction of visible light. Called meta-materials, scientists say the three-dimensional materials (3-D) could one day bend light to create an illusion of invisibility, a phenomenon they call negative refraction.

In two papers published this week in the journals Science and Nature, researchers at the University of California, Berkeley, describe the development of the meta-materials.

They create the effect of invisibility by bending light back and forth and around objects, eliminating shadows and reflecting back no light so the objects cannot be seen.

Xiang Zhang is a professor of mechanical engineering and lead author of the papers.

Zhang likens the effect of completely bending light around an object to make it invisible to water channeled by a rock in a stream.

"When they pass this object, the light rays can actually be bended around an object, then re-emerged after this object," he said. "So, for observers downstream, they won't see any shadows of the object. So, people cannot see the object and [that's how it makes] the object invisible."

Negative refraction can also create some interesting optical illusions.

As an example, scientists say fish in an aquarium normally appear closer to the top of the tank than they are. With negative refraction, the fish on the bottom of the aquarium appear to be floating above it.

But the ability to bend light backward could lead to more useful important applications, according to Zhang.

Zhang says negative refraction could result in something he calls a super lens powerful enough to view miniscule DNA molecules and the tiniest live viruses.

"We can use that to [watch] how the tiny, tiny biological machines work inside of cells," he said. "And how to understand, for example, how cancer develops and how disease develops."

Zhang also envisions more mundane but practical applications to the light-bending technology. He says negative refraction will make it possible to develop even smaller computer chips and higher density DVDs that store hundreds, or perhaps thousands of movies on a single disc.