Abstract A Nd:YLF laser system with frequency doubled output is described. Several aspects concerning energy and stability of the pulses will be discussed. The system consists of a CW mode locked Nd:YLF oscillator and two double pass amplifiers having a total small signal gain of about a million which means care must be taken to prevent self-oscillations. Due to saturation effects the energy per micropulse is limited to 20 μJ, resulting in 8 μJ at the second harmonic frequency (526.5 nm). For the frequency conversion KTP type II is used. The short term timing stability was measured using a spectrum analyser and found to be less than 200 fs with a width of 450 Hz. The amplitude fluctuations over the 15 μs macropulse are determined by the saturation behaviour of the amplifiers and the shot to shot stability of the amplifiers. Third and fourth harmonic generation is under study.