Output beam characteristics of a toric concave mirror laser resonator

The output beam characteristics of a toric concave mirror laser resonator are discussed. The experiments of the toric concave mirror laser resonator, the plane-concave stable resonator, and the parallel plane resonator with the same Fresnel number of 17.25 are done on HUST2000 high-power transverse flow CO2 laser. The output laser beam of 1820 W with a doughnutlike distribution, the output laser beam of 1860 W with a Laguerre-Gaussian (LG) transverse electromagnetic modes (TEM)60 distribution and the laser beam of 1000 W with are approximate LG TEM30 distribution are obtained, respectively, at the same discharge current of 5 A. The scanning welding test on 316L stainless steel shows that the output beam of the toric concave mirror laser resonator can used for deep penetration laser welding, the welding depth is >2.4 mm at a velocity of 1 m/min, whereas that of other two resonators cannot be used for deep-penetration laser welding because of low beam quality or low output power. This resonator can be used in the laser with a large transverse gain size to improve beam quality greatly without sacrificing the output power.