Characteristics of XeCl laser radiation from an unstable cavity with asymmetric radiation coupling-out

The divergence of the radiation from a repetitively pulsed electric-discharge transversely excited XeCl laser with an unstable cavity and asymmetric coupling-out of the radiation was studied experimentally. A cavity with convex mirrors made it possible to generate radiation with a near-diffraction divergence and to retain the energy at the level of 40% — 50% of the energy of a laser with a plane — plane cavity. The generation of a circular spot with a uniform intensity distribution by focusing a rectangular beam is described. Calculations and experiments are used to show that this phenomenon does not arise from diffraction and is not a result of the interaction of the laser radiation with the medium or with the target material.