  Invisibility cloaks have become one of the most outstanding developments
among the wide range of applications in the field of metamaterials. So far,
most efforts in invisibility science have been devoted to achieving practically
realizable cloak designs and to improving the effectiveness of these devices in
reducing their scattering cross-section (SCS), a scalar quantity accounting for
the total electromagnetic energy scattered by an object. In contrast, little
attention has been paid to the opposite side of the technology: the development
of more efficient techniques for the detection of invisibility devices. For
instance, the SCS ignores the phase change introduced by the cloak, as well as
the angular dependence of the incident and scattered waves. Here, we propose to
take advantage of the smarter way in which diffraction tomography processes all
this overlooked information to improve the efficiency in unveiling the presence
of invisibility devices. We show that this approach not only results in a
considerable sensitivity enhancement in the detection of different kinds of
cloaks based on both scattering cancellation and transformation optics, but
also enables us to even obtain images depicting the approximate shape and size
of the cloak. As a side result, we find that scattering cancellation coatings
may be used to enhance the contrast of tomographic images of closely-packed
particles. Our work could be easily extended to the detection of sound cloaks.
