Development of a Convex Mirror Cooling Methode for a TEA CO2 Coaxial Output Unstable Resonator Laser
J. Chen, W. Yu, H. Zhu and Z. Cheng
A coaxial unstable resonator using a vortex tube to cool the convex mirror has been developed for the transversely excited atmospheric TEA CO2. 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, particularly 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.
Keywords: TEA CO2 laser, unstable resonator, convex mirror, Vortex-Tube-Cooling, beam quality, finite element method.