Experimental Analysis of Output Phase Properties for the High-Power Q-Switched Slab Nd:YAG Laser

Many factors of intracavity perturbation will degrade the output power and beam quality for high power passive Q-switched slab laser. In the paper, the experiment test on the output beam quality of a passive Q-switched zig-zag slab Nd:YAG laser has been performed by adopting Hartmann-Shack (H-S) wavefront sensor and Zernike mode reconstruction theory, namely wavefront properties can be fully obtained by processing the image of beam spot matrix. In this way, the PV and RMS values of the wavefront aberration, every order zernike aberrations can be acquired accurately, and the point spread function (PSF) of the beam and the distribution of circle energy can also be obtained by further calculation, so the beam-quality can be known fully. The experimental results show that the wavefront aberration of laser is mainly concentrated in the frontal 10 ranks of Zernike aberration, mainly including the defocus A3, the low-order astigmatism A5, the coma aberration A6 and the spherical aberration A10 because of the crystal thermal effect and the intracavity aberrated perturbation.