Researchers at the Berkeley Lab just developed what could be the most effective invisibility cloak we’ve seen outside of a sci-fi movie. The ultra-thin cloak is made of near-microscopic brick-shaped gold antennas, and it resolves some of the shortcomings of previous technologies. Because of its ingenious design, the cloak works nearly as well as a perfectly flat mirror, reflecting light in such a way that makes it seem like the cloak and the object it’s hiding are not there at all. The researchers say that even the edges of the object are invisible with the new device.
We love innovations that bring us a little closer to having real life superpowers. Superhuman night vision, the strength to scale buildings, and the ability to disappear in plain sight are all things we’d like to do, if only technology would give us a way. That last one – the ability to become invisible – might be one of the most appealing of superpowers, and we have in fact published a whole slew of articles on previous attempts at making a garment that can render its wearer invisible.
Imagine a cloak made from thousands or perhaps millions of tiny mirrors. Mirrors reflect light and, as everyone knows, what is behind a mirror remains hidden because the mirror replaces what the viewer observes with a reflection. Most modern attempts at an invisibility cloak work on the same principles, by reflecting light and thereby hiding the subject in question. However, they run into some problems, especially around the edges of objects, where the tiny mirrors can bend light or reflect it back in colors, similar to a prism. Faults like that make it possible to detect an item that is supposed to be hidden, if you have a sharp eye.
The new development addresses that problem. The ultralight film is made from a 50-nanometer-thick layer of magnesium fluoride topped with tiny, brick-shaped gold antennas, each 30 nanometers thick. With an average human hair measuring about 100,000 nanometers wide, it’s important to realize just how thin this material is, because that aids in its performance. Due to its thinness and flexibility, the cloak can be draped over any object, and it can be fine-tuned to match virtually any background.
Images via Xiang Zhang group and Berkeley Lab/UC Berkeley