PERFORATING METHOD AND LASER MACHINING APPARATUS

摘要

A perforating method and a laser machining apparatus are provided to shorten the time for measuring the height of the surface of a workpiece and improve the machining efficiency although irregularities of about 10 to 30 mum are present in the surface of a table. A laser machining apparatus comprises: a memory unit for memorizing results in which heights of the surface of the table having a workpiece mounted thereon are measured in a matrix form; a detection unit for detecting the height directional position of a condensing lens; and an arithmetic unit for obtaining a height of the surface of the table at an arbitrary point by an operation, wherein: a height of the arbitrary point on a top face of the workpiece mounted on the table is measured before machining; the height of the surface of the table at the arbitrary point is obtained by the operation using the heights of the surface of the table at four points surrounding the arbitrary point; a difference between the measured height of the top face of the workpiece and the height of the surface of the table obtained by the operation is set as a plate thickness of the workpiece; and the condensing lens is positioned in the height direction by setting the height of the top face of the workpiece at other machining position as the sum of the plate thickness and the height of the surface of the table at the machining position obtained by the operation using the height of the surface of the table at four points surrounding the machining position.