Super-Gaussian resonators for long-pulse XeCl lasers

Near-diffraction-limited laser beams of high energy have been achieved with a long-pulse (110-ns) XeCl laser fitted with a super-Gaussian unstable cavity of magnification M = 2.7. It has been found that when the super-Gaussian output coupler is replaced with a hard-edge aluminized mirror of radius equal to the super-Gaussian mirror spot size, the output laser energy is reduced by 10%, whereas the beam divergence increases more than 50%.