on so called cloaking devices.

‘A metamaterial’s (non-textile) microscopic structures are bigger than atoms, but they’re smaller than the wavelength of certain waves—optical, acoustic, electromagnetic. And because of that, it’s possible for them to redirect incoming energy. That can be useful for beam-steering antennas, acoustic trickery, and cloaking devices.

I’m not going to call them invisibility cloaks, even though that’s the preferred term of most of the researchers building these things. Because they’re just…not. They’re not flexible, and they don’t drape over the objects they’re built to hide. The first functional cloaking device was more like a container—a thick ring that surrounded the object it was hiding, bending a single wavelength of light around it. Other so-called carpet cloaks look more like a hollow pyramid set down on top of the hidden object, the surface of which reflects incident light in a way that makes it look like there’s nothing but a flat surface underneath.’

‘Instead of resting over or around the object to be concealed, the Berkeley group wrapped a thin layer of gold nanoantennas—only 80 nanometers thick—around the target. Those nanoantennas distort light waves as they hit the surface, and the scientists oriented them to reflect the light so it looks like it’s bouncing off a flat mirror instead of a few weirdly-shaped microbumps.

But despite its physical similarity to a piece of clothing, the Berkeley device’s functionality is still closer to the Yautja tech. Like the Predator’s cloaking device, it only works for certain wavelengths—well, actually, just one, 730 nanometers (that’s red light).’

http://www.wired.com/2015/09/cloaking-device-predator-less-harry-potter/

 

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