| 摘要 |
An illumination device (4) is provided with the following: an optical member (5) provided with an annular- or horseshoe-shaped light guide layer (10) and a diffusion layer (11) that are stacked in a center axis (O) direction, the light guide layer (10) having a light-receiving surface facing a tangent line direction; and a light introducing member (8) that is disposed to the outside of the optical member (5) in the radial direction thereof, the light introducing member causing illumination light from the light-receiving surface thereof to be incident in the tangent line direction in the light guide layer (10). The diffusion layer (11) diffuses, by volume scattering, the illumination light incident from the light guide layer (10). The optical member (5) emits, from at least one edge surface (5a) in the axis (O) direction, the illumination light that has been emitted from the diffusion layer (11) in the center axis direction. |
