Laser apparatus and laser machining method

A laser apparatus comprising:

• a first vacuum chamber including a process region, wherein machining is performed on a target substrate in the process region;
• a carrier disposed in the first vacuum chamber, the carrier configured to fix the target substrate;
• a chamber window disposed in one surface of the first vacuum chamber, wherein the chamber window is made of a transparent material;
• a laser module disposed to overlap the chamber window;
• a first protection window positioned between the carrier and the chamber window;
• a second vacuum chamber disposed at a first side of the first vacuum chamber;
• and
• a transfer unit configured to transfer the first protection window to the second vacuum chamber;
• and.
• a contamination detector configured to detect whether the first protection window is contaminated,
• wherein the first protection window is disposed between the contamination detector and the chamber window.