Development of the Convex Mirror Cooling of TEA CO_2 Coaxial Output Unstable Resonator Laser

摘要

A coaxial unstable resonator using a vortex tube to cool the convex mirror has been developed for the transversely excited atmospheric TEA CO_2. The time dependent thermal deformation of the convex mirror was analysed by using the finite element method. The simulated results indicate that the Vortex-Tube-Cooling system can remarkably reduce the thermal deformation of the convex mirror, particulary over a long working time. Also, the experimental verification was carried out and the results show that the developed Vortex-Tube-Cooling coaxial unstable resonator system is an effective and applicable cooling method for convex mirrors. The divergence angle drops from 3.19 mrad to 1.78 mrad, and the times-diffraction-limit factor decreases from 6.94 to 1.78 when using the Vortex-Tube-Cooling system when the repetition rate is 3 Hz and the continuous working time is 300 s.