Negative-branch unstable resonator Nd:YAG laser.

The results of an experimental investigation of the performance characteristics of a Q-switched Nd:YAG laser utilizing a negative-branch unstable resonator is presented. Measurements indicate that near diffraction-limited beam quality has been attained with a system in the rangefinder/designator energy category. In a performance comparison with a conventional parallel-plane mirror resonator, the unstable resonator was found to produce equally efficient operation with greatly superior beam radiance and tolerance to mirror misalignment.