An injection-locked unstable resonator rare-gas halide discharge laser of narrow linewidth and high spatial quality

An oscillator-amplifier KrF discharge laser system capable of providing up to 400 mJ output with 0.1-cm
^-1
linewidth in a 20-ns pulse is described. The output beam divergence is described and shown to be affected by the discharge current. The output beam is near the diffraction limit in the direction parallel to the discharge and about three times the diffraction limit transverse to the discharge. Operation with XeCl at up to 250 mJ with similar linewidth and spatial quality is also described.