| 摘要 |
PROBLEM TO BE SOLVED: To provide a light irradiation device suppressing variations in light intensity due to light interference.SOLUTION: A laser beam from a light source part 4 is guided along an optical axis J1 of an irradiation optical system 5 to an irradiation surface 320. A division lens part 62 of the irradiation optical system includes a plurality of element lenses 620 arranged in an arrangement direction perpendicular to the optical axis, and light transmitting through the plurality of element lenses enters a plurality of translucent elements 610 of a phase difference generation part 61. A light condensing part 63 overlaps, on the irradiation surface, irradiation ranges 50 of light from the plurality of element lenses. The light path lengths of three translucent elements respectively corresponding to three target element lenses arranged continuously in the arrangement direction is determined so that the two target element lenses adjacent to each other forms a target element lens pair, and a light intensity peak position on the irradiation surface generated by interference of light transmitting through one target element lens pair is different from the peak position of the other target element lens pair. This suppresses variations in light intensity due to light interference on the irradiation surface.SELECTED DRAWING: Figure 3 |
