Shaped teflon can hide objects from microwaves from one direction

Look out for mass-produced invisibility cloaks thanks to an entirely new way of designing and manufacturing them out of materials such as Teflon. The new approach is to create a computer model of the cloak in the form of a conventional material with fixed light bending properties. The model simulates how this conventional material distorts light as it passes by. The computer then changes the shape and topology of the material to reduce this distortion. By repeating this process many times, it is possible to find a topology that minimises the distortion of light so that it remains more or less unchanged as it passes by. The result is an invisibility cloak; not a perfect one but one that can hold its own against many of those made of metamaterials.

Today, Lu Lan at Zhejiang University in China and a few pals have actually created the first invisibility cloak designed using topology optimisation. They carved it out of Teflon and it took them all of 15 minutes using a computer-controlled engraving machine. “The fabrication process of a sample is substantially simplified,” they say.

The resulting “Teflon eyelid” invisibility cloak hides a cylindrical disc of metal the size of poker chip from microwaves. But crucially, its performance closely matches the prediction of the computer simulation

The same approach can work in optical wavelengths. “Such a cloaking setup won’t be a big problem to replicate in the THz or even optical spectrum,” they say.

Next the researchers want to develop the technique to create cloaks that work over a range of frequencies and at a range of angles.

Arxiv – Experimentally demonstrated an unidirectional electromagnetic cloak designed by topology optimization (10 pages)

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