Third-harmonic generation using an ultrahigh-spectral-brightness ArF* source

Tunable coherent radiation in the vicinity of 64 nm has been produced by third-harmonic generation of the output of an ultrahigh-spectral-brightness ArF*source in various simple gaseous media. The following performance parameters of the ArF* system are used: pulse energy, ~300 mJ; pulse duration, ~7 nsec; spectral width, <260 MHz; beam divergence, ~5microradx15microrad; and repetition rate up to 10 Hz. Third-harmonic generation with peak powers up to 30 W has been observed in an apparatus that eliminates photoabsorption of the third harmonic in the differential pumping stages.