Divergence of radiation from an electric-discharge CO2 laser having an unstable resonator

The results are presented of an experimental investigation into the divergence of radiation from a quasi-cw CO₂ laser having an unstable resonator. It was found that the onset of inhomogeneity in the active medium, caused by instability of the self-sustained gas discharge, led to a substantial increase in the divergence of the laser radiation before its power fell. This effect must be taken into account when optimizing laser operating regimes. Laser radiation entering the resonator after reflection from an irradiated target can greatly influence the power, stability, and divergence of the radiation, leading to disruption of the normal intensity distribution in the focal plane. This effect is observed even when the target is rotated through large angles relative to the direction of the incident radiation.