We present experimental and theoretical results on aberration control in solid state laser amplifiers and resonators. In lasers with diffraction-limited beam quality, aberrations cause diffraction losses that reduce the output power. In laser amplifiers, aberrations in the active medium degrade the beam quality of the amplified beam. Adaptive optics can be used to correct for the aberrations and thus increase output power and beam quality, respectively.
The required precision of the adaptive aberration correction can be estimated with a simple mode expansion model in which an aberrated TEM00 mode is expanded into Gauss-Hermite modes. Apart from these theoretical results we will present experimental results for a MOPA (Master-Oscillator-Power-Amplifier) laser system consisting of a Nd:YVO4 master oscillator and two Nd:YAG power amplifiers. A micromachined deformable mirror was used in a closed-loop system to correct for the thermo-optic aberrations of the amplifiers. A beam with a beam quality of M2= 2.5 at an out power of 80 W was obtained. The deformable mirror was controlled by a genetic algorithm.© (2003) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.