Illumination lens, illumination optical system, and endoscope

An illumination optical system of an endoscope, the illumination optical system comprising:

• an illumination lens consisting of a first lens and a second lens that are arranged in this order from a light source side toward an irradiation target side;
• and
• a point light source configured to emit a plurality of light rays to the illumination lens, wherein angles of the plurality of light rays incident on the illumination lens with respect to an optical axis of the illumination lens are different from each other,
• wherein the illumination lens is configured to directly receive the plurality of light rays from the point light source and cause all of the plurality of light rays to intersect on the irradiation target side at positions outside the second lens,
• wherein a surface of the first lens closest to the light source side and a surface of the first lens closest to the irradiation target side are spherical convex surfaces,
• a surface of the second lens closest to the light source side is a spherical convex surface, and
• in a case where a radius of curvature of the surface of the first lens closest to the light source side is denoted by Rf1, a radius of curvature of the surface of the first lens closest to the irradiation target side is denoted by Rr1, and a radius of curvature of the surface of the second lens closest to the light source side is denoted by Rf2, Conditional expression (1) is satisfied,
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