Patent ID: 7843633

Claim:
A laser processing apparatus, comprising: a fiber laser light source emitting laser light; a collimator collimating the laser light emitted from said fiber laser light source in a state where the laser light is enlarged to a predetermined beam diameter; a first condenser lens condensing the laser light emitted from said collimator on a predetermined part of an object to be processed; an optical isolator arranged on a light path between said collimator and said first condenser lens, said optical isolator emitting laser light, as forward propagation light that has reached from the collimator side, in parallel to a direction of incidence of the laser light, and emitting return light, as reverse propagation light that has reached from the first condenser lens side, at a predetermined angle with regard to a direction of incidence of the return light; and a spatial filter arranged on a light path between said collimator and said optical isolator, said spatial filter having: a second condenser lens temporarily condensing the laser light from said collimator; a third condenser lens, arranged closer to said optical isolator than a focal point of the laser light having passed through said second condenser lens, collimating the laser light condensed by said second condenser lens; and a pinhole mask arranged such that a pinhole is located at a focal point of the laser light formed between said second and third condenser lenses.