Patent ID: 8767782

Claim:
A laser irradiating device comprising: a plurality of lasers configured to emit a plurality of laser beams; an irradiating face slantingly arranged with respect to the plurality of laser beams; an isolator configured to remove return light of the plurality of laser beams; means for forming shapes of the plurality of laser beams on the irradiating face in an elliptical shape; and means for moving irradiating positions of the plurality of laser beams on the irradiating face in a first direction and a direction reverse to the first direction, and moving the irradiating positions of the plurality of laser beams on the irradiating face in a second direction, wherein each of the plurality of lasers is configured to irradiate to emit each different region of the irradiating face at a time, wherein each of the plurality of lasers is configured to emit a laser beam slantingly with respect to a vertical direction of the irradiating face in the middle of the laser beam, and wherein each of incident angles φ of the plurality of laser beams to the irradiating face is the same or satisfy φ≧arcsin (W/2d) when widths of the plurality of laser beams are set to W and a thickness of a substrate is set to d—so that no interference is caused unless incident light and reflected light on a rear surface of the substrate are overlapped.