Patent ID: 7459655

Claim:
A laser beam processing machine comprising a chuck table for holding a workpiece, a laser beam application means comprising a laser beam oscillation means and a condenser equipped with an objective lens for converging a laser beam oscillated by the laser beam oscillation means to apply it to the workpiece held on the chuck table, and a processing-feed means for moving the chuck table and the laser beam application means relative to each other in a processing-feed direction, wherein a focusing point shifting means for shifting the position of the focusing point of the laser beam converged by the objective lens is arranged between the laser beam oscillation means and the objective lens, and the focusing point shifting means comprises a first lens for transmitting the laser beam oscillated by the laser beam oscillation means, a second lens for transmitting a laser beam that has passed through the first lens, and an optical path length changing means for changing the length of an optical path between the first lens and the second lens, wherein the optical path length changing means is constituted by a first deflection mirror means which is composed of a first mirror for reflecting and deflecting a laser beam that has passed through the first lens, a second mirror, located at a predetermined interval from the first mirror, for reflecting and deflecting a laser beam reflected by the first mirror, and an angle adjusting actuator for adjusting the setting angles of the first mirror and the second mirror with respect to the first lens while maintaining the predetermined interval between the first mirror and the second mirror and a second deflection mirror means which is composed of a third mirror for reflecting and deflecting a laser beam reflected by the second mirror of the first deflection mirror means, a fourth mirror, located at a predetermined interval from the third mirror, for reflecting and deflecting a laser beam reflected by the third mirrors and an angle adjusting actuator for adjusting the setting angles of the third mirror and the fourth mirror with respect to the second mirror while maintaining the predetermined interval between the third mirror and the fourth mirror.