Imagine throwing a cloak over your head and becoming invisible to the outside world. That possibility, once the stuff of science fiction and fantasy, could soon become a reality.
An invisibility cloak, or a cloth that renders its wearer completely invisible to others, is not a new concept. It's been a popular device for generations of novelists, and scientists have been working on the idea for years.
Researchers at the University of California at Berkley may have come the closest yet to developing the real thing.
According to Dr. Xiang Zhang, a Berkley-based materials scientist who helped develop the cloak, the prototype takes advantage of the latest advances in optics technology.
Normally, we see an object because light scatters as it bounces off its surface, and the distorted waves reveal its shape. But the new cloak, he says, stops those bounces and distortions, which renders the object effectively invisible.
Studded with millions of tiny reflective nano-antennas made of gold — each one about one-thousandth the thickness of a human hair — the cloak stops the light from scattering and distorting, so it appears like the light reflecting from a flat surface.
“Now they can have a reflection from a floor or a mirror or a wall – you do not see the object anymore," said Zhang.
There are other invisibility cloaks, but these are designed to bend light around an object. They're bulky and cannot conceal objects that aren't smooth.
The tiny mirrors in Zhang’s cloak, however, solve this problem. They are so tiny, the skintight cloth covers nooks and crannies and bumps, and still reflects light as if it were a smooth mirror.
So far, the researchers have been working with very tiny objects — 36-by-36 micrometers in size, visually undetectable — but Zhang says the science would be the same on a macro scale, and the technology can be scaled up to cover humans, possibly in the next five to seven years.
The military may be interested in making soldiers and aircraft invisible, but Zhang says there could be a number of everyday uses of the cloak, including cosmetics.
“Where people can make sizeable bellies become six-packs, that can be flattened up visually, not [for] real. Scars on the face and things that [the cloak] can make disappear," said Zhang.
Zhang says the cloak could also be wrapped around the rear frame in a car window, making the “blind spot” disappear so people can see approaching vehicles.
An article describing the invisibility cloak technology is published in the journal Science.