  The aim of an invisibility device is to guide light around any object put
inside, being able to hide objects from sight. In this work, we propose a novel
design of dielectric invisibility media based on negative refraction and
optical conformal mapping that seems to create perfect invisibility. This
design has some advantages and more relaxed constraints compared with already
proposed schemes. In particular, it represents an example where the time delay
in a dielectric invisibility device is zero. Furthermore, due to impedance
matching of negatively refracting materials, the reflection should be close to
zero. These findings strongly indicate that perfect invisibility with optically
isotropic materials is possible. Finally, the area of the invisible space is
also discussed.
