Patent ID: 7864823

Claim:
A laser irradiation apparatus comprising: a first laser light source configured to emit a first polarized pulse laser beam; a second laser light source configured to emit a second polarized pulse laser beam which is different from the first polarized pulse laser beam; an optical path combining member configured to guide the first polarized pulse laser beam and the second polarized pulse laser beam to pass through a same optical path; a polarization control member arranged in a direction perpendicular to a traveling direction of laser beams, wherein the polarization control member includes a first polarization control portion and a second polarization control portion, each of which controls a polarization state of beam components of the pulsed laser beam from the optical path combining member, wherein the polarization state controlled by the first polarization control portion is different from that controlled by the second polarization control portion; and a laser beam superimposing member configured to superimpose the pulsed laser beam which has passed through the first polarization control portion and the pulsed laser beam which has passed through the second polarization control portion with each other on a surface to be irradiated of an object, wherein the first laser light source and the second laser light source emit linearly-polarized pulse laser beams of which polarization directions are at 90Â° to each other, wherein the first polarization control portion and the second polarization control portion are quarter wave plates which each have an optical axis at an angle of 45Â° with respect to each of the polarization directions of the pulsed laser beams emitted from the first laser light source and the second laser light source, and wherein the optical axes of the first polarization control portion and the second polarization control portion are at 90Â° to each other.