Limits from the Funk Experiment on the Mixing Strength of Hidden-Photon
  Dark Matter in the Visible and Near-Ultraviolet Wavelength Range
  We present results from the FUNK experiment in the search for hidden-photon
dark matter. Near the surface of a mirror, hidden photons may be converted into
ordinary photons. These photons are emitted perpendicular to the surface and
have an energy equal to the mass of the dark matter hidden photon. Our
experimental setup consists of a large, spherical mirror with an area of more
than 14 m$^2$, which concentrates the emitted photons into its central point.
Using a detector sensitive to visible and near-UV photons, we can exclude a
kinetic-mixing coupling of stronger than $\chi \approx 10^{-12}$ in the mass
range of 2.5 to 7 eV, assuming hidden photons comprise all of the dark matter.
The experimental setup and analysis used to obtain this limit are discussed in
detail.
