Beam quality of a XeCl excimer laser vs. the repetition-rate

We present the results of beam quality measurements of a XeCl (lambda = 0.308 mu m) laser, equipped with a generalized self-filtering unstable resonator (GSFUR), while operating in the burst mode at repetition rates of up to 50 Hz. In particular, we have measured the behavior of the laser-energy distribution (both in the near- and far-field) and of the beam-angular-stability (BAS) vs. the repetition rate. The time-evolution of the divergence within the single laser pulse was also measured. The GSFUR is able to achieve a nearly diffraction-limited divergence since the beginning of the laser pulse, and to maintain the values of the times-diffraction-limit number, of the M-2 parameter and of the BAS independent of the repetition rate. The BAS was measured by using two different techniques, and the results suggest that the reliability of the standards commonly used may depend upon the experimental set-up.