  Partially coherent light beams are encountered both in classical and in
quantum optics. Their coherence properties generally depend on the correlation
properties of their sources. In this paper, we propose a technique for
controlling the coherence properties of optical beams in laboratory
environment. The technique is based on the fact that coherence properties of
partially coherent electromagnetic beams can be changed on refraction and on
reflection, and that the changes can be controlled by varying the angle of
incidence.
