Cloaking technology, stealth paint, fancy eyeliner. The applications are endless.
A carbon nanotube coating developed at the University of Michigan acts as a “magic black cloth” that conceals an object’s three-dimensional geometry and makes it look like a flat black sheet.
The 70-micron coating, or carbon nanotube carpet, is about half the thickness of a sheet of paper. It absorbs 99.9 percent of the light that hits it, researchers say.
You could use it to completely hide any 3D attributes of an object,
said Jay Guo, a professor in the Department of Electrical Engineering and Computer Science and principal investigator.
It’s not cloaking, as the object can still cast a shadow. But if you put an object on a black background, then with this coating, it could really become invisible.
A paper on the research is newly published online in Applied Physics Letters.
To demonstrate this concept, the researchers made a raised, microscopic tank shape on a piece of silicon. They then grew the carbon nanotube carpet on top of the entire silicon chip. In photos taken through an optical microscope, they show that the tank is imperceptible. As a control, they did this again, carving out a rectangle that was not coated with carbon nanotubes. The rectangle is visible on this chip, but the tank remains hidden.
Human eyes perceive an object based on how it reflects or scatters light. The “refractive index” of this new coating is similar to that of air, meaning light traveling through air doesn’t scatter or reflect when it hits the coating.