  It has been proposed that an additional U(1) sector of hidden photons could
account for the Dark Matter observed in the Universe. When passing through an
interface of materials with different dielectric properties, hidden photons can
give rise to photons whose wavelengths are related to the mass of the hidden
photons. In this contribution we report on measurements covering the visible
and near-UV spectrum that were done with a large, 14 m2 spherical metallic
mirror and discuss future dark-matter searches in the eV and sub-eV range by
application of different electromagnetic radiation detectors.
