  Cherenkov Telescopes are equipped with optical dishes of large diameter -- in
general based on segmented mirrors -- with typical angular resolution of a few
arc-minutes. To evaluate the mirror's quality specific metrological systems are
required that possibly take into account the environmental conditions in which
typically these telescopes operate (in open air without dome protection). For
this purpose a new facility for the characterization of mirrors has been
developed at the labs of the Osservatorio Astronomico di Brera of the Italian
National Institute of Astrophysics. The facility allows the precise measurement
of the radius of curvature and the distribution of the concentred light in
terms of focused and scattered components and it works in open air. In this
paper we describe the facility and report some examples of its measuring
capabilities.
