Results of an experimental and theoretical analysis of the proprerties of a LD pumped laser using a stable resonator and second harmonic conversion crystal are presented. The influence of thermal lens effect on laser output mode and beam quality has been discussed briefly by using the transfer matrix theory. In this paper, further experiment on the output beam quality of a LD pumped acousto-optic Q-switched laser has been also performed by adopting Shack-Hartmann wavefront sensor and Zernike mode reconstruction theory. Using this method, PV and RMS error of aberration wavefront, the first 35-order Zernike aberrations can be acquired. Furthermore, Strehl ratio curve of output beam and the distribution of circle energy can also be obtained by further calculation, so mode properities can be comprehensively understood. Experimental results show that the beam wavefront aberration is mainly concentrated in the first 15 orders of Zernike aberration, mainly including the defocus A3, the low-order astigmatism A4 and A5, the coma and spherical aberration because of the thermal-lens effect.
Design and experimental demonstration of a high conversion efficiency OPCPA pre-amplifier for petawatt laser facility
