LASER PROCESSING DEVICE AND LASER RADIATION METHOD

摘要

A laser processing apparatus includes a laser irradiation unit has a structure providing an intensity distribution of the laser beam focused on the grain-oriented electrical steel sheet on a cross-section in a direction perpendicular to the scanning direction on the grain-oriented electrical steel sheet so as to satisfy Ib/Ia ‰¤ 2, where Ra 1 and Ra 2 are distances between the centroid of the intensity distribution and positions at which the intensity integration value from the centroid of the intensity distribution is 43% of the total intensity integration value, beam intensities Ia 1 and Ia 2 are intensities of the laser beam corresponding to Ra 1 and Ra 2 , respectively, Ia is the average value of Ia 1 and Ia 2 and Ib is the beam intensity at the centroid of the intensity distribution.