Taking a page from Harry Potter and his invisibility cloak, physicists at the Karlsruhe Institute of Technology (KIT) in Germany, believe they found a way to create an optical invisibility cloak from diffused scattered light. Diffused scattered light – like fog, frosted window panes or clouds – lets light in but hides the light source.
Currently with the laws of physics, you can’t make something completely invisible in terms of color and polarization, but according to Robert Schittny, an author of the study which was recently published in the journal, Science, this property of light-scattering media can be used to hide objects inside, creating an optical invisibility cloak.
Like all good phycisists, Schittny performed an experiment to test his theory. He used an extended light source to illuminate a plexiglas tank filled with a white, cloudy thick liquid.
Then, he placed simple, metal cylinders (a few centimeters in diameter) painted with white dispersion paint inside the plexiglass tank. By filling the tank with the liquid, combined with back lighting, the metal cylinders inside the tank cast a visible shadow on the tank wall. But, to pass the light around the metal cylinders, the physicists applied a transparent silicon material with a light-scattering melamine microparticles which created a thin shell around the cylinders
The silicon shell around the cylinders caused a faster diffusion of light, meaning it passed the light around the cylinders or cloaked them, and they didn’t cast a shadow anymore. According to Schittny, the disappearance of the shadow indicates successful cloaking.
“We will have to wait a long time for real applications, but it might be possible to produce frosted glass panes for bathrooms with integrated invisible metal bars or sensors to deter burglary,” adds Schittny.