| 摘要 |
PROBLEM TO BE SOLVED: To provide a method for detecting focal point shift of a laser capable of detecting and correcting focal point shift due to thermal effect at a low cost.SOLUTION: A processing head (1) is positioned with respect to a reference measurement surface (11) having a small opening (10) so that a laser beam axis (5) passes through the small opening. A laser beam (4) is emitted focusing on the reference measurement surface or the front or rear of the surface. The level of radiant light (14) radiated from at least a part of the periphery of the small opening on the reference measurement surface is measured by a radiant light measurement sensor (12), and a focal point shift amount is obtained using the measured value to correct the focal point of the laser beam. |
