Scientists construct ultra-thin invisibility cloak

Bristol – Scientists have constructed a new ultra-thin invisibility cloak made from a mesh of fine copper that is capable of making a hand-sized cylinder invisible to microwaves.

While most people associate such cloaks with boy magician Harry Potter and his adventures, there would real-life uses for them, such as securing your valuables with tiny security tags that it would be impossible for a thief to see or even find.

“In principle, this technique could also be used to cloak light,” explained Professor Andrea Alu from the University of Texas at Austin in a paper published in the Institute of Physics and German Physical Society’s New Journal of Physics.

Microwaves and light occupy different bands of the electromagnetic spectrum and are differentiated only by wavelength.

Unlike previous cloaking studies where meta-materials have been used to divert, or bend, the incoming waves around an object, researchers this time used a new, ultra-thin layer called a “meta-screen” to cancel out the waves as they are scattered off the cloaked object.

Electromagnetic fields, including light and microwaves, consist of waves and the human eye sees objects because these waves rebound off their surface.

“When the scattered fields from the cloak and the object interfere, they cancel each other out and the overall effect is transparency and invisibility at all angles of observation,” said co-author of the study Professor Alu.

Researchers demonstrated the new cloaking device’s functionality using an 18-centimetre cylindrical rod, but also predict that oddly shaped and asymmetrical objects could be cloaked using the same principles.

The meta-screen cloak was made by attaching strips of 66-micrometre-thick copper tape to a flexible 100-micrometre-thick polycarbonate film in a fishnet design.

“The advantages of the mantle cloaking over existing techniques are its conformability, ease of manufacturing and improved bandwidth,” explained Alu.

In future, the team hopes to test the technology with light.

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