Use of unstable resonators in achieving the diffraction divergence of the radiation emitted from high-gain pulsed gas lasers

An analysis is made of the possibilty of using unstable resonators in reducing the divergence of the radiation emitted from high-gain pulsed gas lasers. A qualitative discussion is given of the properties of unstable resonators in such lasers, and their optimal parameters are determined. Experiments are reported on pulsed copper vapor lasers. It is reported that the average output power achieved in these experiments is 5 W when the divergence is close to the diffraction limit. A comparison is made of the characteristics of lasers with plane-parallel and telescopic resonators.