ABSTRACT
In recent years, transformation optics has become an active new field. It has been popularized through the idea of J. B. Pendry that an invisibility cloak can be designed by transforming space and considering the corresponding equivalent material properties. A simple setting for transformation optics is to consider cylindrical devices where the transformation concerns only the radial distance. In order to obtain the components of the equivalent permeability and permittivity tensors in the Cartesian coordinates, it is necessary to perform first an initial transformation from Cartesian to cylindrical coordinates, then the radial transformation concerned, and finally the back transformation from cylindrical to Cartesian coordinates. A dramatic example of transformation optics devices is the superlens: Even if these devices were proposed a few years before the rise of transformation optics, they are nicely interpreted as corresponding to a folding of the space on itself.
