XeCl laser system with a 25 cm × 25 cm output aperture

A description is given of a high-power excimer laser system. The first results are reported of the amplification of a beam with a divergence close to the diffraction limit. Beyond the preamplifier, the 5 cm × 6 cm laser beam contains 50% of the radiation energy in the diffraction core. At the output from the system an irradiation brightness of 2 × 10¹⁴ W cm^-2 sr^-1 was obtained. A numerical model of the amplification of the radiation, taking into account the influence of the amplified spontaneous emission, was devised. It demonstrated a satisfactory agreement between the calculated and experimental data.