Carbon nanotubes have been at the forefront of a lot of scientific research, with the atom-thin structures used for their strength, durability, and optical properties. Now, a team from the University of Michigan have demonstrated that by airbrushing an object with arrays of the tubes, known as forests, it is possible to create a layer which perfectly absorbs the light that hits it. While this isn't quite see-through invisibility as we know it from science fiction, it creates an illusion of a flat black object with no discernible texture: anything painted with the technology would take on a two-dimensional appearance, since no light is reflected by the surface. Additionally, the refractive index of carbon nanotubes and air is very similar, meaning there is little distortion as light passes between the two mediums.
The image above shows their experiment — the top line is under an electron microscope, and shows a bare silicon etching roughly 80 micrometers wide, which is then coated in the nanotube forest. The second line shows the same images using visible light, with the final pair (images C and F) showing the contrast when a mark is made on the nanotubes.
Similar tech is already employed by NASA to blacken the inside of its telescopes, and researchers are also looking into the potential uses in fiber optics for noise reduction, but this is the first time that the nanotubes have been used to conceal objects. The research is due to be published in Applied Physics Letters in the coming months.