Divergence and polarisation of radiation of a wide-aperture chemical DF laser with an unstable resonator

Influence of a plane-parallel plate, placed inside an unstable resonator and entirely overlapping the beam cross section, on the polarisation and divergence of wide-aperture DF-laser radiation is studied at various angles of plate inclination to the resonator axis. It is shown that the plate inside a resonator has no effect on the radiation divergence and only requires a corresponding shift of a convex mirror in order to keep the resonator confocal. A noticeable change in the radiation polarisation has been observed only at angles of plate inclination greater than 20°; at angles of above 45° the radiation becomes actually linearly polarised.