Laser machining device and bellows device

A laser machining device comprising:

• a machining table on which a workpiece is placed;
• a laser oscillator that emits a laser beam;
• a light-guide optical system that deflects the laser beam emitted from the laser oscillator;
• an extensible and contractible bellows that has a shape of a cylinder and surrounds an optical path of the laser beam after the light-guide optical system deflects the laser beam;
• a bend mirror that deflects the laser beam having passed through the bellows in a direction toward the machining table, the bend mirror being coupled to the bellows;
• a machining head that irradiates the workpiece with the laser beam deflected by the bend mirror;
• a unit that supplies purge gas to form an air current within the bellows, the air current having a downstream side on a side of the light-guide optical system;
• an abnormality detector including a light emitting unit that emits a light beam which is separate from the laser beam in a direction perpendicular to the laser beam near an end portion of the bellows at a side of the light-guide optical system, and a light receiving unit that measures an amount of received light of the light beam;
• and
• a control unit that selectively controls the laser oscillator to stop emitting the laser beam when the amount of received light of the light beam in the light receiving unit falls below a first threshold.