BBC: One of the inventors of “transformation optics” has taken another step forward in the development of structures that can redirect light, hiding the objects behind them. David Smith of Duke University and his colleagues created a diamond-shaped structure that eliminates some of the imperfections of previous invisibility cloaks. The device was able to perfectly hide a 7.5-cm-diameter, 1-cm-tall cylinder from detection by microwaves. However, the cloak only worked from one direction. Microwaves from any other direction could see the cylinder. Because of the wavelength differences between microwaves and visible light, this doesn’t make invisibility to sight any more promising, but hiding objects from microwaves could be useful for the military and telecommunications.