  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.
