ScienceDaily — Carbon nanotubes, tiny cylinders composed of one-atom-thick carbon lattices, have gained fame as one of the strongest materials known to science. Now a group of researchers from the University of Michigan is taking advantage of another one of carbon nanotubes' unique properties, the low refractive index of low-density aligned nanotubes, to demonstrate a new application: making 3-D objects appear as nothing more than a flat, black sheet.
The refractive index of a material is a measure of how much that material slows down light, and carbon nanotube "forests" have a low index of refraction very close to that of air. Since the two materials affect the passage of light in similar ways, there is little reflection and scattering of light as it passes from air into a layer of nanotubes. The Michigan team realized they could use this property to visually hide the structure of objects.