Fig. 1

Beam profile of a tophat intensity distribution and b Gaussian intensity distribution at 600 mJ and 650 mJ output power, respectively. The beam profiles were measured at 750 mm and 1250 mm distances from the respective laser; the beam was reflected to these positions by an optical window to reduce the laser fluence on the beam profiler. (Note: Due to the difference in beam divergence angle of two intensity distributions, different distances were used to completely separate the beam spots avoiding interference in the beam profile measurement.).