Patent ID: 7402773

Claim:
A laser beam processing machine comprising a chuck table for holding a workpiece, a laser beam application means for applying a laser beam capable of passing through the workpiece 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, the laser beam application means comprising a laser beam oscillation means, an optical transmission means for transmitting a laser beam oscillated from the laser beam oscillation means and a condenser lens for converging a laser beam transmitted by the optical transmission means, wherein the optical transmission means comprises a birefringence lens for separating the laser beam oscillated from the laser beam oscillation means into normal light and abnormal light; and the condenser lens converges respectively the normal light and the abnormal light separated by the birefringence lens to form the focal point of the normal light and the focal point of the abnormal light by the laser beam to simultaneously form deteriorated layers of different depths in the workpiece, wherein a birefringence deflection plate for displacing the optical axis of the laser beam applied to the condenser lens in a processing-feed direction is interposed between the birefringence lens and the condenser lens.