The anti-cloak

A kind of transformation media, which we shall call the anti-cloak, is proposed to partially defeat the cloaking effect of the invisibility cloak. An object with an outer shell of anti-cloak is visible to the outside if it is coated with the invisible cloak. Fourier-Bessel analysis confirms this finding by showing that external electromagnetic wave can penetrate into the interior of the invisibility cloak with the help of the anti-cloak. (C) 2008 Optical Society of America.