Cool Optical Camoflage

NF Reporter · 02-26-2007, 06:00 PM

Alright ill admit i wasnt sure how to spell that correctly, but you get the idea. Looks like an invisibility suit isnt far off.

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waltky · 08-10-2008, 09:07 PM

More on it...

Invisibility cloak one step closer, scientists say
Sun Aug 10, 2008 WASHINGTON - Scientists have created two new types of materials that can bend light the wrong way, creating the first step toward an invisibility cloaking device.

Quote:

One approach uses a type of fishnet of metal layers to reverse the direction of light, while another uses tiny silver wires, both at the nanoscale level. Both are so-called metamaterials -- artificially engineered structures that have properties not seen in nature, such as negative refractive index.

The two teams were working separately under the direction of Xiang Zhang of the Nanoscale Science and Engineering Center at the University of California, Berkeley with U.S. government funding. One team reported its findings in the journal Science and the other in the journal Nature. Each new material works to reverse light in limited wavelengths, so no one will be using them to hide buildings from satellites, said Jason Valentine, who worked on one of the projects.

"We are not actually cloaking anything," Valentine said in a telephone interview. "I don't think we have to worry about invisible people walking around any time soon. To be honest, we are just at the beginning of doing anything like that." Valentine's team made a material that affects light near the visible spectrum, in a region used in fiber optics.

More Invisibility cloak one step closer, scientists say | Science | Reuters

waltky · 01-27-2012, 12:14 AM

Granny says it'd be a good way fer Obama to sneak up on Ahmadinejad an' smack him upside the back o' the head...

Scientists in US a step closer to 3D ‘invisibility cloak’
Fri, Jan 27, 2012 - Scientists in the US reported a further step toward a celebrated “invisibility cloak” by masking a large, free-standing object in three dimensions.

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The laboratory work is the latest advance in a scientific frontier that uses novel materials to manipulate light, a trick that is of huge interest to the military in particular. Reporting in the New Journal of Physics, researchers at the University of Texas in Austin cloaked an 18cm cylindrical tube from light in the microwave part of the energy spectrum. Those hoping for a Harry Potter-style touch of wizardry would be disappointed. To the human eye, which can only perceive light in higher frequencies, the tube would not have been invisible at all , but the researchers said the experiment is important proof of a principle that so-called plasmonic meta-materials can achieve a cloaking effect.

A warplane cloaked with such materials could achieve “super-stealth” status by becoming invisible in all directions to radar microwaves, co-lead researcher Andrea Alu said. Plasmonic meta-materials are composites of metal and non-conductive synthetics made of nanometer-sized structures that are far smaller than the wavelength of the light that strikes them. As a result, when incoming photons hit the material, they excite currents that make the light waves scatter. The new experiment entailed making a shell of plasmonic meta-materials and placing the cylinder inside, then exposing the combination to microwaves.

Microwaves scattered by the shell ran into microwaves bounced from the object, preventing them sending a return signal to the viewer. “When the scattered fields from the cloak and the object interfere, they cancel each other out, and the overall effect is transparency and invisibility at all angles of observations,” Alu said. Any shape of object can be masked, he added. The feat is a step forward because other techniques have entailed bending light around two-dimensional objects or, in 3D, masking microscopic bumps on mirrors or reflectors, an approach called “carpet cloaking,” the authors said. The new concept could be modified for visible light, although any cloaked objects would be very small, in the micrometer range, as the plasmonic effect is linked to the wavelength of the light, Alu said in a telephone interview.

Even so, there could be important applications for microwave meta-materials, he said. “Camouflaging to radar is one important application, a super-stealth device to make objects invisible to radar,” he said. “What we are thinking about is not necessarily cloaking the whole warplane, but some hotspots, a part such as the tailplane that you would want to cloak because it reflects most of the energy [from microwave radar].” Another outlet would be in laboratories, filtering out the “backscatter” of light from the tip of high-powered optical microscopes. Unwanted light such as this impairs images of the object that is being scrutinized and skews measurements.

Scientists in US a step closer to 3D ?invisibility cloak? - Taipei Times