| 摘要 |
PROBLEM TO BE SOLVED: To provide a dark field of view illumination device that is less in the number of components and is robust in positioning an optics.SOLUTION: An illumination device emitting parallel light having a ring-like light flux cross-section comprises: a surface light source that radially emits light from an emission surface; a first specular mirror that is arranged to face the surface light source, and reflect the light from the surface light source in a radial direction crossing an optical axis of emission light of the illumination device by a specular surface provided in an outer side surface of the first specular mirror; and a second specular mirror that is provided in an inner side surface of a lens barrel surrounding the first specular mirror, and causes the specular surface of the first specular mirror to reflect specular light by the first specular mirror in a direction parallel to the optical axis. The light reflected by the second specular mirror can be parallel light having the ring-like light flux cross section. |
