Method for adjusting the focus position of a laser beam

Abstract

This method for setting the focus position of a laser beam comprises a first step of inserting a first holder for holding a protective glass and an aperture for limiting a beam diameter of a guide laser beam into an insertion opening provided in a lower part of a laser head; a second step of emitting the guide laser beam; and a third step of determining whether the focus position of the laser beam is within a predetermined range, which includes a reference position, based on a comparison between a test piece provided at the reference position according to the focus position of the guide laser beam and the beam diameter of the guide laser beam indicated on the test piece during the execution of the second step.