New super-thin, flexible invisibility cloak wows Harry Potter fans

Harry Potter fans rejoice: Researchers have devised an ultra-thin invisibility cloak that can mask three-dimensional objects -- if you’re observing that object in microwave light, that is.

With butterbeer and Bertie Bott’s every flavor beans on the market, perhaps it was only a matter of time before invisibility cloaks edged from Hogwarts fantasy toward engineered reality.

Previous research has focused on metamaterials -- man-made materials engineered into tiny repeating patterns that can bend light waves around an object, rather than letting it bounce and scatter from the surface and into our eyes, allowing us to see it.

But a new study, published in the New Journal of Physics, describes a method called “mantle cloaking,” which uses a less bulky, more conformable “metascreen” fashioned with 66-micrometer-thick copper strips and 100-micrometer polycarbonate film in a fishnet design. When light hits the cloak, the metascreen cancels out the scattering rays, effectively rendering the object transparent.

“The wave passes through the object as if it is not there, so you would be able to ‘see’ through the object once it is cloaked,” study coauthor Andrea Alu, an engineer at the University of Texas at Austin, said in an email. “That is the main challenge in cloaking.”

And given that thin, flexible plastic can more easily conform to an object’s shape, the new design makes for a much better candidate for invisibility cloaks, the authors said.

Of course, microwave light waves are large -- making it relatively less challenging to cloak the 7-inch rod in the scientists’ experiment, according to the authors. Visible light waves are much smaller, which means that at least in the very near future, only tiny micrometer-sized objects could be hidden from plain sight -- and they’re too small to be seen with the naked eye anyway.

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