Invisibile Curiosity

Metamaterials digital to create invisibility cloaks


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Metamaterials are artificial compounds that interact with the sound (most other types of waves) and the light in unusual ways, showing the characteristics that are not found in nature. Currently researchers that define the new concept of “metamaterials digital” provide an easier way to produce these compounds – which are already being used for testing and iperlenti invisibility cloaks, which are not subject to the limits of conventional materials.

“The basic idea relating to metamaterials is to mimic the way in which the atoms interact with the light, but with artificial structures still smaller than the wavelength of the light itself” – Boris Kuhlmey University of Sydney explains in The Conversation. “In this way, the optical properties will no longer be reserved to those of the constituent materials, and may be designed in an almost arbitrary.”

The way he behaves a metamaterial depends on the properties of its constituent units and as subunits are organized. Cristian Della Giovampaola and Nader Engheta, University of Pennsylvania, propose to use only two subunits with opposite properties. Defined as “bit metamaterials,” they are like the numbers 1 and 0 of a binary system. Have used parts of the nanoscopic silica and silver, interacting with light in ways quite different: one acts as the metal, while the other insulator.

Both researchers have used a computer simulation to create the layered structures that make up the bytes of high function and complexity. Once the bytes were “digitized” the material that resulted had its own characteristics, different from its constituent subunits.

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The idea of a cloak of invisibility depends on the manipulation of light so that the electronic circuits can control the flow of electrons. When the electromagnetic waves (such as light) hitting an object of metal or wood, are dispersed; here’s the way we see the object. Let us assume that there is an artificial material that covers it – a possible bending wave around it without being dispersed – that way we would not be able to see the object.

Manipulate the light all the time: for example, the magnifying lenses focus at a single point, while the mirrors reflect it, making change direction. Metamaterials, however, can make things even more phenomenal. “I can bend light, to disperse, to manipulate it in many different ways,” says Tiffany Walsh of Deakin University.

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Metamaterials can be created to produce negative angles of refraction. If the water in the glass showcases negative refraction, the image of the pen under the water line is reversed as seen in a mirror.

A pen sticking out of a glass of water never appears as a straight line. The surface of the water bends the light, and it, traveling from the pen to the observer from below the border of the water, has a different angle of refraction with respect to the light that travels from the top. However, unlike the naturally occurring materials, metamaterials are able to play the angles of refraction negative, reversing the image (see image above). Engheta explains the difference between the two shots with the pen inside the glass, in this video of 2013 describing metamaterials:


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