Electron beam pumped argon-excimer laser using an unstable resonator

An unstable resonator was used for an e-beam pumped argon-excimer laser in the VUV-spectral region, for the first time to our knowledge. Adoption of the unstable resonator achieved successful operations of the high output energy of 28 mJ without any damage of the resonator mirrors. Beam divergence of the argon-excimer laser output was measured with a beam profiler, which was developed in our laboratory, It was found that the output beam involved a large ASE output. The maximum focused fluence at the center of the output beam was measured to be 42 mJ/cm². The coherence of the argon-excimer laser was degraded by the ASE, which was caused due to high gain condition of the argon-excimer laser