We consider the problem of identifying the material properties from boundary measurements. For the conductivity case, this is known as Calderon problem: “Is it possible to determine the electrical conductivity inside a domain from the boundary voltage and current measurements?” The uniqueness for Calderon problem holds when the conductivity is restricted to be isotropic, where by definition the material properties are independent of direction. For the anisotropic case, the uniqueness fails to hold since, using a change of coordinates, it is possible to make two different anisotropic conductivity profiles which give the same boundary data. We will see how to make “Harry Potter’s invisibility cloak” using a singular change of coordinates, which blows up a point to the region being cloaked. In addition, the regularization or the approximation of singular cloaking will be explained. Finally, I will provide a new method of constructing very effective near-cloaking structures in order to achieve enhanced near-invisibility.
