Patent ID: 7205502

Claim:
A reflector-mirror drive shaft controller for a laser beam machine that comprises a bed, a pallet which is disposed on the bed and holds a workpiece, a column which moves along an X axis, that is, in a longitudinal axis of the bed, a saddle which is supported by the column and moves along a Y axis orthogonal to the X axis, a machining head on a laser machining tool which is supported by the saddle and moves along a Z axis perpendicular to a plane formed by the X axis and Y axis, a machining lens in the laser machining tool, a laser oscillator device, and a reflector-mirror driven by the reflector-mirror drive shaft controller along a drive shaft for keeping a length of an optical path between the laser oscillator device and the machining lens constant, wherein the reflector-mirror drive shaft controller moves the reflector-mirror along the drive shaft to keep the length of the optical path between the laser oscillator device and the machining lens constant, and the reflector-mirror drive shaft controller includes means for giving an offset to movement of the reflector-mirror as a function of a range of thickness of the workpiece to adjust a diameter size of a beam incident to the machining lens across the range of thickness of the workpiece.