# US 10,441,148 B2 · Illumination lens and illumination optical system for an endoscope > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,441,148 B2 - Document ID: US10441148B2 - Status: Granted - Kind: B2 - Application number: 15/980,145 - Filed: 2018-05-15 - Published: 2018-11-22 - Granted: 2019-10-15 - Earliest claimed: 2017-05-19 - Assignees: FUJIFILM Corporation - Applicants: FUJIFILM Corporation - Inventors: Kazuki Inoue - Web page: https://patentgrep.com/patent/US10441148B2 ## CPC - A61B 1/0623: {for off-axis illumination} - A61B 1/00096: {Optical elements} - A61B 1/07: using light-conductive means, e.g. optical fibres - G02B 23/2461: {Illumination} - F21V 5/008: {Combination of two or more successive refractors along an optical axis} - A61B: DIAGNOSIS; SURGERY; IDENTIFICATION (usefulness limited to only animals A61D) - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - F21V: FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR ## Abstract An illumination lens consists of two lenses consisting of a first lens and a second lens arranged in this order from a light source side, and surfaces of all the lenses have a planar shape or a convexly spherical shape. An incident surface of the first lens is a convex surface, and an emission surface of the second lens is a flat surface. An intersection of a ray incident in parallel to an optical axis at a height of 0.25×H and a ray incident in parallel to the optical axis at a height of 0.5×H is positioned only inside the illumination lens in a case in which an outer diameter of the first lens is denoted by 2H. Predetermined Conditional Expression related to a focal length of the illumination lens and a focal length of the first lens is satisfied. ## Claims ### Claim 1 An illumination lens that is used in an illumination optical system for an endoscope, the illumination lens consisting of two lenses consisting of a first lens and a second lens arranged in this order toward an object side from a light source side, wherein surfaces of all the lenses have a planar shape or a convexly spherical shape, an incident surface of the first lens on which light generated from a light source is to be incident is a convex surface, an emission surface of the second lens from which light toward an object is to be emitted is a flat surface, an intersection of a ray incident on the incident surface in parallel to an optical axis at a height of 0.25×H from the optical axis and a ray incident on the incident surface in parallel to the optical axis at a height of 0.5×H from the optical axis is positioned only inside the illumination lens in a case in which an outer diameter of the first lens in a direction perpendicular to the optical axis is denoted by 2H, in a case in which a thickness of the second lens along the optical axis is denoted by t, a position of the intersection in a direction of the optical axis is positioned closer to the light source than a position, which is apart from the emission surface of the second lens to the light source side by 0.4×t, and Conditional Expression (1) expressed by “0.61