Invisibility cloak 'step closer'

[The Venetian]

Monday, 11 August 2008 01:53 UK

Scientists in the US say they are a step closer to developing materials that could render people invisible.
Researchers at the University of California in Berkeley have developed a material that can bend light around 3D objects making them "disappear".
The materials do not occur naturally but have been created on a nano scale, measured in billionths of a metre.
The team says the principles could one day be scaled up to make invisibility cloaks large enough to hide people.
Stealth operations
The findings, by scientists led by Xiang Zhang, were published in the journals Nature and Science.
The light-bending effect relies on reversing refraction, the effect that makes a straw placed in water appear bent.
Previous efforts have shown this negative refraction effect using microwaves—a wavelength far longer than humans can see.



"In order to have the 'Harry Potter' effect, you just need to find the right materials for the visible wavelengths." Ortwin Hess

The new materials instead work at wavelengths around those used in the telecommunications industry—much nearer to the visible part of the spectrum.
Two different teams led by Zhang made objects made of so-called metamaterials—artificial structures with features smaller than the wavelength of light that give the materials their unusual properties.
One approach used nanometre-scale stacks of silver and magnesium fluoride in a "fishnet" structure, while another made use of nanowires made of silver.
Light is neither absorbed nor reflected by the objects, passing "like water flowing around a rock," according to the researchers. As a result, only the light from behind the objects can be seen.
Cloak and shadow


"This is a huge step forward, a tremendous achievement," says Professor Ortwin Hess of the Advanced Technology Institute at the University of Surrey. "It's a careful choice of the right materials and the right structuring to get this effect for the first time at these wavelengths."
There could be more immediate applications for the devices in telecommunications, Prof Hess says.
What's more, they could be used to make better microscopes, allowing images of far smaller objects than conventional microscopes can see.
And a genuine cloaking effect isn't far around the corner.
"In order to have the 'Harry Potter' effect, you just need to find the right materials for the visible wavelengths," says Prof Hess, "and it's absolutely thrilling to see we're on the right track."

Source

[Trefelin]

This is mad, read about this today, Harry Potter isn't so far fetched after all! Next we'll be hearing of Mandrake Plantations to ease the plight of the starving Ethiopians!

[The Venetian]

Please note the info below is from 2005.

Real-World Applications

While an invisibility cloak is an interesting application of optical camouflage, it's probably not the most useful one. Here are some practical ways the technology might be applied:

• Pilots landing a plane could use this technology to make cockpit floors transparent. This would enable them to see the runway and the landing gear simply by glancing down.
• Doctors performing surgery could use optical camouflage to see through their hands and instruments to the underlying tissue. See Tachi Lab: Optical Camouflage: oc-phantom.mpg to watch a video of how this might work.
• Providing a view of the outside in windowless rooms is one of the more fanciful applications of the technology, but one that might improve the psychological well-being of people in such environments.
• Drivers backing up cars could benefit one day from optical camouflage. A quick glance backward through a transparent rear hatch or tailgate would make it easy to know when to stop.

One of the most promising applications of this technology, however, has less to do with making objects invisible and more about making them visible. The concept is called mutual telexistence: working and perceiving with the feeling that you are in several places at once. Here's how it works:

• Human user A is at one location while his telexistence robot A is at another location with human user B.
• Human user B is at one location while his telexistence robot B is at another location with human user A.
• Both telexistence robots are covered in retro-reflective material so that they act like screens.
• With video cameras and projectors at each location, the images of the two human users are projected onto their respective robots in the remote locations.
• This gives each human the perception that he is working with another human instead of a robot.

Right now, mutual telexistence is science fiction, but it won't be for long as scientists continue to push the boundaries of the technology. For example, pervasive gaming is already becoming a reality. Pervasive gaming extends gaming experiences out into the real world, whether on city streets or in remote wilderness. Players with mobile displays move through the world while sensors capture information about their environment, including their location. This information is used to deliver users a gaming experience that changes according to where they are and what they are doing.
For more information on the invisibility cloak, optical camouflage and related topics, check out the links on the next page.

Source

Also read :
HowStuffWorks "How Invisibility Cloaks Work"

HowStuffWorks "Altered Reality"