| 摘要 |
Illumination light is efficiently distributed to a target, and luminous intensity distribution is enhanced. An endoscopic illumination optical system includes a light guide bundle in an insertion portion of an endoscope, for guiding light from a light source, and a lens for distributing the light from the bundle to a target. The lens includes two inflection points in a vertical cross section including an optical axis of the lens, and includes a first concave surface inside the two inflection points, and an annular second concave surface outside the inflection points, continuous with an outer periphery of the first surface. The second surface faces an outer peripheral edge of the bundle in an optical axis direction. A distance A between the inflection points in the vertical cross section and a diameter D of an end surface of the satisfy 0.75@A/D@0.85 (1). |
