Laser processing apparatus

A laser processing apparatus comprising:

• a chuck table configured to hold a workpiece;
• a laser beam irradiating unit configured to irradiate the workpiece held on the chuck table with a pulsed laser beam;
• a processing feed unit configured to processing-feed the chuck table and the laser beam irradiating unit relative to each other;
• an indexing feed unit configured to indexing-feed the chuck table and the laser beam irradiating unit relative to each other;
• and
• a control unit;
• the laser beam irradiating unit including
• a laser oscillator,
• a first mirror configured to reflect the laser beam emitted from the laser oscillator and propagate the laser beam to a second mirror,
• the second mirror configured to reflect the laser beam reflected from the first mirror and propagate the laser beam to a third mirror,
• the third mirror configured to reflect the laser beam reflected from the second mirror and propagate the laser beam to a processing point for processing the workpiece,
• a first power measuring unit configured to measure power of leakage light of the laser beam transmitted through the first mirror,
• a second power measuring unit configured to measure power of leakage light of the laser beam transmitted through the second mirror,
• a third power measuring unit configured to measure power of leakage light of the laser beam transmitted through the third mirror, and
• a condensing lens configured to condense the laser beam propagated by the third mirror and irradiate the workpiece with the condensed laser beam,
• wherein the control unit allows to measure the power of the leakage light of the laser beam by the power measuring units while irradiating the workpiece with the laser beam.