To provide an irradiation device capable of stably applying a laser beam having a further homogeneous intensity distribution.
The irradiation device includes: a laser light source 11; a polarization beam splitter 13 (polarization separation means) for separating laser light emitted from the laser light source 11 into P polarized light (first linearly-polarized light) and S polarized light (second linearly-polarized light); a cylindrical lens array pair 14 (luminous flux division means) for dividing the first or second linearly-polarized light into a plurality of luminous fluxes; a quarter wavelength plate array 15 where first quarter wavelength plates 15A for converting luminous flux to clockwise circular polarized light, and second quarter wavelength plates 15B for converting luminous flux to counterclockwise circular polarized light are alternately arranged in an X-axis direction (first direction) orthogonal to an optical axis Z; and a condenser lens 16 (projection optical system) for condensing the clockwise circular polarized light and the counterclockwise circular polarized light to be emitted toward a surface 3S (irradiation object surface).
Yasushi Santanzaki
Masao Hasebe
Takaaki Tanaami