Optical Conformal Mapping and Dielectric Invisibility Devices
  An invisibility device should guide light around an object as if nothing were there, regardless where the light comes from. Ideal invisibility devices are impossible due to the wave nature of light. This paper develops a general recipe for the design of media that create perfect invisibility within the accuracy of geometrical optics. Here the imperfections of invisibility can be made arbitrarily small to hide objects that are much larger than the wavelength. Using modern metamaterials, practical demonstrations of such devices seem possible. The method developed here can be also applied to escape from detection by other forms of waves such as sound. 
Ulf Leonhardt