Patent ID: 8294123

Claim:
A laser beam machining method of irradiating an object to be machined with machining laser light beam, from a specific irradiation direction, said method comprising steps of: irradiating the surface of the object with a plurality of adjustment laser light beams as reference light beams for adjusting a converging point of the machining laser light beam, from respective irradiation directions different from each other and further through optical paths different from an optical path of the machining laser light beam, the plurality of adjustment laser light beams having a relationship such that a beam spacing therebetween on the surface of the object changes according to a depth position of the converging point from the surface of the object, irradiation areas of the plurality of adjustment laser light beams satisfying a specific positional relationship with respect to the converging point of the machining laser light beam; monitoring irradiation areas of the plurality of adjustment laser light beams, on the surface of the object; exacting a positional information of the surface of the object with respect to the converging point of the machining laser light beam, on the basis of information of the irradiation areas and the specific positional relationship; moving the object so as to make the beam spacing obtained from the positional information become a predetermined beam spacing; and irradiating the object, whose position has been adjusted, with the machining laser light beam, after moving the object.