Patent ID: 8039778

Claim:
A laser processing apparatus, comprising: a laser light source emitting a laser beam; a monitor light source emitting a monitor light with a wavelength different from that of the laser beam; an irradiation optical system applying the laser beam emitted from the laser light source and the monitor light emitted from the monitor light source to an object and surroundings thereof so that an application angle onto the object is the same while scanning an irradiation position of the laser beam and the monitor light along a predetermined direction; an optical filter provided on the opposite side to the irradiation optical system with respect to the object, the optical filter interrupting the laser beam and transmitting the monitor light; a photo-detector detecting the monitor light transmitted through the optical filter; and a control section controlling a start and a stop of pulse oscillation of the laser beam emitted from the laser light source, wherein the control section stops the pulse oscillation of the laser beam with respect to the laser light source in the case in which the monitor light applied from the irradiation optical system is detected by the photo-detector; while it starts the pulse oscillation of the laser beam with respect to the laser light source in the case in which no monitor light applied from the irradiation optical system is detected at the photo-detector.