Adaptive Optics for Industry and Medicine pp 250-259 | Cite as
Aberrations of a Master-Oscillator-Power-Amplifier Laser with Adaptive Optics Correction
Summary
Beam quality and efficiency of high-power solid state lasers are limited by aberrations of the active medium. The aberrations are due to temperature gradients in the laser crystals that in turn are due to the inevitable heat generation in the crystal. The aberrations lead to high diffraction losses of the laser resonator and reduced output power.
We use a birefringence-compensation scheme consisting of a relay-imaging telescope and a 90° polarization rotator to eliminate the stress-induced birefringence. In order to further improve the beam quality, the remaining aberrations of the thermal lens have to be eliminated. It is important to know the type and strength of the aberrations to determine the requirements of the adaptive mirror.
We present the investigation of aberrations in a MOPA cw-Nd:YVO4/Nd:YAG laser system in which we employ an adaptive membrane mirror in order to compensate for the aberrations of the power amplifier. A genetic algorithm is used to control the adaptive mirror. A suitable power-in-the-bucket measurement behind a diffraction-limited aperture generates the beam quality signal for the feedback loop. The beam quality (M2) is improved by a factor of 2.8.
Keywords
Beam Quality Spherical Aberration Adaptive Optic Deformable Mirror Adaptive MirrorPreview
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