Gas contaminant effect in a discharge-excited ArF excimer laser

4 , O₂ and N₂ in a discharge-excited ArF-excimer laser. Measured characteristics include laser pulse energy, small-signal gain, and laser spectrum. Measurement results indicate that laser pulse energy degradation for such impurities (<100 ppm) is mainly due to optical absorption. It has also been found that for O₂ contaminants laser pulse energy degradation is strongly dependent on operational repetition rates; at higher repetition rates, an increased concentration of O₂ impurities results in a reduced small-signal gain and a consequent decline in laser pulse energy. Received: 12 June 1997/Revised version: 3 December 1997