  We present experimental results on the optical absorption spectra of
epitaxial graphene from the visible to the terahertz (THz) frequency range. In
the THz range, the absorption is dominated by intraband processes with a
frequency dependence similar to the Drude model. In the near IR range, the
absorption is due to interband processes and the measured optical conductivity
is close to the theoretical value of $e^{2}/4\hbar$. We extract values for the
carrier densities, the number of carbon atom layers, and the intraband
scattering times from the measurements.
