Laser processing apparatus

A laser processing apparatus for forming a dividing groove in a wafer by irradiating an upper surface of the wafer held by a chuck table with a laser beam, the laser processing apparatus comprising:

• a laser oscillator configured to emit the laser beam;
• a slit configured to narrow a width of the laser beam emitted from the laser oscillator to a width corresponding to the dividing groove to form the dividing groove of a predetermined width;
• a slit moving mechanism configured to move the slit in a direction corresponding to a width direction of the dividing groove;
• an adjusting unit configured to make a center of the slit and a cross-sectional center of the laser beam entering the slit coincide with each other in a direction in which the slit moving mechanism moves the slit;
• a mirror configured to reflect the laser beam emitted from the laser oscillator and irradiate the wafer held on the chuck table with the laser beam;
• and
• a camera disposed on a back side of the mirror, and configured to image a transmitted laser beam as the laser beam emitted from the laser oscillator and passed through the mirror,
• wherein the adjusting unit includes:
• a center identifying section configured to identify a cross-sectional center of the transmitted laser beam on a basis of brightness of pixels of an image captured by the camera, and
• a second control section configured to control the slit moving mechanism on a basis of the cross-sectional center of the transmitted laser beam, the cross-sectional center being identified by the center identifying section, such that the cross-sectional center of the laser beam and the center of the slit coincide with each other in a moving direction of the slit.