Posts Tagged stealth

Silence is Golden and also a Fetching Cloak

Scientists have shown off the blueprint for an “acoustic cloak”, which could make objects impervious to sound waves.

The technology, outlined in the New Journal of Physics, could be used to build sound-proof homes, advanced concert halls or stealth warships.

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The Spanish team who conducted the new work believe the key to a practical device are so-called “sonic crystals”.

These artificial composites – also known as “meta-materials” – can be engineered to produce specific acoustical effects.

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“The idea of acoustic cloaking is to deviate the sounds waves around the object that has to be cloaked,” said Jose Sanchez-Dehesa of the Polytechnic University of Valencia, one of the researchers behind the new work.

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Nanoengineers create Light “Sponge”

The perfect light \"sponge\"“Three things can happen to light when it hits a material,” says Boston College Physicist Willie J. Padilla. “It can be reflected, as in a mirror. It can be transmitted, as with window glass. Or it can be absorbed and turned into heat. This metamaterial has been engineered to ensure that all light is neither reflected nor transmitted, but is turned completely into heat and absorbed. It shows we can design a metamaterial so that at a specific frequency it can absorb all of the photons that fall onto its surface.”

The metamaterial is the first to demonstrate perfect absorption and unlike conventional absorbers it is constructed solely out of metallic elements, giving the material greater flexibility for applications related to the collection and detection of light, such as imaging, says Padilla, an assistant professor of physics.

Metamaterial designs give them new properties beyond the limits of their actual physical components and allow them to produce “tailored” responses to radiation. Because their construction makes them geometrically scalable, metamaterials are able to operate across a significant portion of the electromagnetic spectrum.

This means that the metal is blacker than black.

(via boingboing)

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