Abstract: A laser processing apparatus includes at least a laser oscillator, optical fiber (30), and laser head (40). Laser head (40) includes at least first and second shield glasses (45) and (47) and first and second light receivers (51) and (52) inside second housing (41). In first and second shield glasses (45) and (47), first and second coating films (46) and (48) are respectively provided on light receiving surfaces of laser light (LB). First light receiver (51) receives laser light (LB) reflected by first coating film (46) and outputs a first light receiving signal, and second light receiver (52) receives laser light (LB) reflected by peripheral portion (48b) of second coating film (48) and outputs a second light receiving signal.

Abstract: Beam splitter (23) is provided with AR coating (24). AR coating (24) has a first reflectance for reflecting a first laser light higher than a second reflectance for reflecting a second laser light. Detector (25) detects reflection light (RL) reflected by beam splitter (23). Detector (25) has a first light receiving sensitivity for receiving the first laser light lower than a second light receiving sensitivity for receiving the second laser light.

Abstract: Collimator lens (21) and focusing lens (22) are provided with AR coating (23). AR coating (23) has a first reflectance for reflecting a first laser light higher than a second reflectance for reflecting a second laser light. Detector (25) detects diffusion light (DL) diffused by collimator lens (21) and focusing lens (22). Detector (25) has a first light receiving sensitivity for receiving the first laser light lower than a second light receiving sensitivity for receiving the second laser light.

Abstract: A laser processing apparatus includes first and second laser oscillators that emit first and second laser lights (LB1), (LB2) having wavelengths different from each other, an optical fiber that guides first and second laser lights (LB1), (LB2), and laser head (50) configured to condense first and second laser lights (LB1), (LB2), respectively, at predetermined positions of a workpiece. Laser head (50) includes optical path difference generation unit (70) provided inside second housing (51). Optical path difference generation unit (70) is configured to make an optical path length of first laser light (LB1) inside second housing (51) longer than an optical path length of second laser light (LB2).

Abstract: In order to separate a material layer from a substrate at the boundary face between the substrate and the material layer, a laser light is applied to a workpiece from the substrate side through a mask, the work having the material layer formed on the substrate. The laser beam is split into a plurality of small area laser light by the mask 44, and two or more irradiation regions are formed on the workpiece. Adjacent irradiation regions are separated from each other, and an edge part of each irradiation region and an edge part of an adjacent irradiation region, which extend in a direction parallel to the relative moving direction of the workpiece, are arranged such that the edge of the irradiation region and the edge of the adjacent irradiation region are sequentially overlapped each other as the work is moved.

Abstract: In order to separate a material layer from a substrate at the boundary face between the substrate and the material layer, a laser light is applied to a workpiece from the substrate side through a mask, the work having the material layer formed on the substrate. The laser beam is split into a plurality of small area laser light by the mask 44, and two or more irradiation regions are formed on the workpiece. Adjacent irradiation regions are separated from each other, and an edge part of each irradiation region and an edge part of an adjacent irradiation region, which extend in a direction parallel to the relative moving direction of the workpiece, are arranged such that the edge of the irradiation region and the edge of the adjacent irradiation region are sequentially overlapped each other as the work is moved.

Abstract: A substrate is separated from a material layer formed on the substrate without generating cracks in the material layer formed on the substrate. In order to separate the material layer from the substrate at a boundary between the substrate (1) and the material layer (2), pulsed laser light (L) is applied, through the substrate (1), to a workpiece (3) having the material layer (2) formed on the substrate (1), while from moment to moment changing an irradiation region with respect to the workpiece (3), in such a manner that the adjacent irradiation regions overlap each other on the workpiece (3). The region where the pulsed laser light (L) is applied to the work (3) is set to satisfy the relationship of S/0.125, where S (mm2) is the area of the irradiation region, and L (mm) is the circumferential length of the irradiation region. Consequently, the material layer can be reliably separated from the substrate without generating cracks in the material layer formed on the substrate.