Metamaterials: Towards invisibility in the visible

Researchers are working to achieve invisibility using three principal methods that are camouflage, transparency, and cloaking. They are developing light-scattering objects that can show transparency by designing them so that their optical appearances are compensated for in-scattering without absorbing light. They need to design materials such that it can move the points of physical space to apparent positions that all remain the same, regardless of the point of view. They are also exploring an approach that involves concealing a region of the physical space and to create the illusion of an unperturbed virtual space with a rectangular grid, which needs light to travel along curved coordinate lines. Some optical cloaking devices are very small and two-dimensional, but can work only in the infrared region not for visible light and can help to design new cloaking devices that can work in visible light.