| 摘要 |
PROBLEM TO BE SOLVED: To provide irradiation light having uniform intensity distribution in an easy manner.SOLUTION: A light irradiation device 31 includes a plurality of lenses 71 arranged with a constant pitch in one arrangement direction orthogonal to an optical axis J1. A laser beam from a light source 4 is guided to the plurality of lenses 71 by a first lens part 6 and split into the arrangement directions. A radiation range 51 of light from the plurality of lenses 71 is overlapped with an irradiation surface 320 on the optical axis J1 by a second lens part 8. When attention is paid to light from one position in the arrangement directions in an emission area 41 of the light source 4, the light split by the plurality of lenses 71 generates on the irradiation surface 320 an interference fringe having bright portions aligned in the arrangement direction with a constant fringe pitch. Indeed, light from an entire width in the arrangement direction on the emission area 41 aligns wide bright portions which are the bright portions of the interference fringe and are wider than the bright portions, in the arrangement direction with the fringe pitch. The widths of the wide bright portions of the light irradiation device 31 are integral multiples of the fringe pitch. This provides irradiation light having uniform intensity distribution in an easy manner. |
