| 摘要 |
PROBLEM TO BE SOLVED: To provide a light irradiation device that secures irradiation light sufficient for a large diameter, and increases/reduces a diameter of the irradiation light.SOLUTION: A light irradiation device 1 has: a lens 3 that allows for reduction in an outward angle with respect to an optical axis 5, and emits incident light from a light source 2; and a liquid crystal optical device 4 to which the emitted light is entered. The liquid crystal optical device 4 has a prism part 13 and a liquid crystal part 14, respectively on a light incident side and on a light emission side. The prism part 13 comprises: a plurality of circular cones 21 that is formed in a center area 6 located on the optical axis 5 by directing an apex toward a liquid crystal part 14 side in an optical axis direction; and a plurality of circumferential protrusions 23 that has a protrusion side directed toward the liquid crystal part 14 side in a peripheral area 7 surrounding the center area 6, and is concentrically arrayed. An inclination of a side face of the circular cone 21 with respect to the optical axis 5 is formed so as to be made steeper than that of an outer peripheral surface of the circumferential protrusion 23. The liquid crystal part 14 changes a refractive index by changing a longitudinal direction of a liquid crystal molecule in accordance with a voltage applied to the optical axis direction. |
