Adaptive Optics Technology Used To Improve The Quality Of Solid-state Laser Beam

When the solid state laser is operating, the waste heat stored in the laser medium cause ununiformity of the temperature distribution in the medium, which will result in the wavefront distortion and the beam quality degradation. In order to minish the beam distortion caused from the thermal effects, the conventional methods are to improve the beam quality passively, such as changing the pump geometry and the structure of the laser. Adaptive optics (AO) technology can be used in the soild laser as a active way to reduce the wavefront destortion and fulfill good beam quality under high average power. The thermodynamic characteristic of thin-disk laser medium and the output wavefront characteristic were studies by theoretical analysis, numerical simulation and experiment, then we got the basic thermal distortion rule of the thin-disk laser. The experiment of improving the wavefront by extra-cavity AO system in the thin-disk laser was carried out. These results will provide references for AO system used in the high power thin-disk DPL laser.The thermodynamic model for the thin-disk laser medium was established. The temperature and the thermal stress distribution in laser medium were got based on the stable thermal differential eguation and the balance equation respectively. Numerical simulations about the thermodynamic characteristic of the Nd:YAG thin-disk laser was done, the distribution of the temperature and the thermal stress in laser medium at different pump conditions were got. The relationships between the thickness of laser medium, the intensity distribution of pump laser and the distribution of the the temperature and the thermal stress in laser medium were discussed.The theoretical model for analyzing the wavefront distortion was established. The method to calculate the wavefront in thin-disk laser was put forward. Numerical simulations about the wavefront optical phase difference (OPD) in different pump conditions was done, the relationship between the OPD and the thickness of laser medium and the relationship between the OPD and the intensity distribution of pump laser were analyed. The result shows that the intensity distribution of pump light is the main factor to influence the distribution of beam aberration.The extra-cavity AO experiments in He-Ne laser and low power Nd:YAG rod laser were carried out, the wavefront distortions were well corrected. The Nd:YAG thin-disk MOPA experimental setup was established for analyzing the thermal distortion in the power amplifier. The wavefront distortions in different pump conditions were measured, the AO experiments to...