Invisibility cloaks slim down

skin cloak

SLEEK AND EFFECTIVE  An ultrathin invisibility cloak hides objects by coaxing light waves to rebound as if they had struck a flat surface, as seen in this illustration.

Courtesy of Xiang Zhang group, Berkeley Lab/UC Berkeley

A new invisibility cloak offers more stealth in a thinner package.

The 80-nanometer-thick “skin cloak,” reported in the Sept. 18 Science, drapes over a micrometer-sized object and renders it undetectable for a specific wavelength of red light. Light waves bounce off the shielded entity as if rebounding off a flat surface. Unlike previous prototypes known as carpet cloaks, the skin cloak is extremely thin, works in open air and doesn’t leave a signature in light that makes the cloak itself detectable.

Penn State optical physicist Xingjie Ni and colleagues say the cloak, which is made of tiny gold antennas stuck on a gold and magnesium fluoride base, can be scaled up to hide even larger items. But scientists say they are still a long way from building cloaks that conceal macroscopic objects in all the wavelengths of light that are visible to the naked eye.

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