A diode pumped laser includes a high reflector and an output coupler defining a resonator. The resonator includes a gain medium and a Q-switch and produces a fundamental beam. A first non-linear crystal is positioned extra-cavity of the resonator along a path of the fundamental beam. The first non-linear crystal generates a second harmonic beam from the fundamental beam. The first non-linear crystal is critically phased matched. A second non-linear crystal is portioned extra-cavity of the resonator along a path of the fundamental beam and the path of the second harmonic beam. The second non-linear crystal produces a third harmonic beam. The second non-linear crystal is critically phased matched.