Beam quality of unstable resonator of TEA CO2 coaxial output laser with vortex tube cooling system

The beam quality of unstable resonator of TEA CO2 coaxial output laser is deteriorated remarkably by the thermal accumulation of the output coupler. In order to improve the beam quality, a vortex tube cooling system of output coupler was adopted. The divergence angle was measured at an average pulse energy of 18.3 J under condition of different frequency with and without using the vortex tube cooling system at real time, and the timesdiffractionlimited factor was studied. The results show that the times diffractionlimited factor was changed from 3.52 to 6.94 without the vortex tube cooling system and from 350 to 3.88 with the cooling system at 3 Hz during an operating time of 300 s.