Invisibility Cloaking Takes a Big Stride At a Small Scale

jan_jes writes: Scientists have devised an ultra-thin invisibility "skin" cloak that can conform to the shape of an object and conceal it from detection with visible light. Although this cloak is only microscopic in size, the principles behind the technology should enable it to be scaled-up to conceal macroscopic items as well. The scientists used brick-like blocks of gold nanoantennas to form the 80-nanometer-thick cloak, which conformed to the arbitrary bumps and dents in the 1,300-square-micrometer sample object. The cloak, a metamaterial engineered to bend light in ways not seen in nature, was able to reflect red light as if it were bouncing off a flat mirror.

Comments

More like a cloth mirror, but still impressive

[140Mandak262Jamuna]

No, it does not shield the object from all directions. The invisibility is available is possible for only one viewing direction, possibly with with narrow angular limits. In that sense it is more like David Copperfield, mirrors and things like railroad cars or jetliners "disappearing". But the impressive thing is that though it reflects light like a plane mirror, it is a cloth that is draped over an arbitrary shape. We have seen reflective patches on jogging suits and jackets of people working near highways. But this one seems to be behave like a virtual plane mirror despite being draped over objects.

Quite interesting, seems to be using diffraction patterns of these bricks. Reminds me of the Material Science 201 class where they talk about X-Ray diffraction pattern of crystalline structure, the Bragg's equation, 2 d sin(theta) = n lambda from the dim recesses of my memory. I could not get it then how the powdered substance with structures oriented in all the planes could be understood by the neat rows of dots, one incident and one reflected ray shown in the diagram. I don't get it now how this cloth could create that diffraction pattern.