Posts Tagged ‘invisibility’

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.

“The fact that we can make a curved surface appear flat also means that we can make it look like anything else. We also can make a flat surface appear curved,” said Penn State University electrical engineering professor Xingjie Ni, the study’s lead author.

The researchers said they overcame two drawbacks of previous experimental microscopic cloaks that were bulkier and harder to “scale up,” or become usable for larger objects.

Ni said the technology eventually could be used for military applications like making large objects like vehicles or aircraft or even individual soldiers “invisible.”

Ni also mentioned some unconventional applications.

How about a cloaking mask for the face? “All the pimples and wrinkles will no longer be visible,” Ni said. How about fashion design? Ni suggested a cloak that “can be made to hide one’s belly.”

http://www.huffingtonpost.com/entry/invisibility-cloak-may-be-moving-closer-to-reality_55febe51e4b0fde8b0ce9afd

Advertisements


Doctoral student Joseph Choi demonstrates a multidirectional ‘perfect paraxial’ cloak using 4 lenses.


Choi uses his hand to further demonstrate his device.


A laser shows the paths that light rays travel through the system, showing regions that can be used for cloaking an object.

Scientists at the University of Rochester have discovered a way to hide large objects from sight using inexpensive and readily available lenses.

Cloaking is the process by which an object becomes hidden from view, while everything else around the cloaked object appears undisturbed.

“A lot of people have worked on a lot of different aspects of optical cloaking for years,” John Howell, a professor of physics at the upstate New York school, said on Friday.

The so-called Rochester Cloak is not really a tangible cloak at all. Rather the device looks like equipment used by an optometrist. When an object is placed behind the layered lenses it seems to disappear.

Previous cloaking methods have been complicated, expensive, and not able to hide objects in three dimensions when viewed at varying angles, they say.

“From what, we know this is the first cloaking device that provides three-dimensional, continuously multidirectional cloaking,” said Joseph Choi, a graduate student who helped develop the method at Rochester, which is renowned for its optical research.

In their tests, the researchers have cloaked a hand, a face, and a ruler – making each object appear “invisible” while the image behind the hidden object remains in view. The implications for the discovery are endless, they say.

“I imagine this could be used to cloak a trailer on the back of a semi-truck so the driver can see directly behind him,” Choi said. “It can be used for surgery, in the military, in interior design, art.”

Howell said the Rochester Cloak, like the fictitious cloak described in the pages of the Harry Potter series, causes no distortion of the background object.

Building the device does not break the bank either. It cost Howell and Choi a little over $US1000 ($1140) in materials to create it and they believe it can be done even cheaper.

Although a patent is pending, they have released simple instructions on how to create a Rochester Cloak at home for under $US100 (114).

There is also a one-minute video about the project on YouTube.

http://www.smh.com.au/technology/sci-tech/scientists-unveil-invisibility-cloak-to-rival-harry-potters-20140927-10n1dp.html