A 1.4-KJ SOLID-STATE POWER OSCILLATOR WITH GOOD BEAM QUALITY

By using three 6-disk amplifiers of 10 cm clear aperture from the Nova laser as the active element in an unstable resonator of magnification M = 3, we achieved a single shot output of 1.4 kJ in a beam which con tains 90% of its energy within twice the theoretical beam divergence. We show that most of the beam quality degradation comes from about one wave of beam tilt during the pulse and that the tilt corrected beam q uality corresponds to a Strehl ratio of almost-equal-to 0.6.