Square laser beam of high power transverse flow CO2 laser and its application

By means of the Collins formula and finite-element method, diffraction integral equation of the square resonator with spherical mirrors is transformed to the finite-element matrix equation, mode-fields of the square aperture resonator is calculated. Experiment with square aperture resonator is done on HUST2000 high power transverse flow CO2 laser. The results show that a square multi-mode beam with uniform comparatively intensity appeares in near field distribution. Laser quenching on 45# steel is done by using the square multi-mode beam and general circle beam. The hardened case caused by the square multi-mode beam is more uniform than general circle beam.