After plugging away for some time at two dimensional invisibility cloaks, researchers have begun experimenting with a cloak that can obscure its contents in three dimensions. While the device only works in a limited range of wavelengths, its relative success should help keep the field moving forward. The invisibility cloaks mentioned among scientists are not really turning anything invisible, but rather playing tricks with the light, misdirecting it so that the objects they encase cannot be seen. Normally, the cloaks only work in two dimensions, so just by changing your point of view a bit, the cloak will become obvious—a limitation scientists want to overcome. The 3D cloak in this case is made of woodpile-structured photonic crystals that can redirect light of wavelengths around the size of the crystals’ rod spacing
