Invisibility cloaks slim down

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.