# US 2025/0146935 A1 · Optical density measuring apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2025/0146935 A1 - Document ID: US20250146935A1 - Status: Published application - Kind: A1 - Application number: 18/932,621 - Filed: 2024-10-31 - Published: 2025-05-08 - Earliest claimed: 2023-11-02 - Assignees: Asahi Kasei Microdevices Corporation - Applicants: Asahi Kasei Microdevices Corporation - Inventors: Takaaki FURUYA; Ryotaro OKUDA - Web page: https://patentgrep.com/patent/US20250146935A1 ## CPC - G01N 21/3504: for analysing gases, e.g. multi-gas analysis - G01N 21/61: Non-dispersive gas analysers {(G01N21/3504 takes precedence)} - G01N 21/03: Cuvette constructions - G01N 21/031: {Multipass arrangements} - G01N 2021/0378: {Shapes} - G01N 2201/0221: Portable; cableless; compact; hand-held - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) ## Abstract A compact and highly accurate optical density measuring apparatus that includes an ellipsoidal mirror and a folding mirror is provided. In the optical density measuring apparatus, the shape of at least a part of the inner surface of a light guiding part is composed of a figure of a part of an ellipsoid E, and a shape of at least a part of another portion of the inner surface of the light guiding part is composed of a figure of a part of a plane or a quadric surface. 60% or more of the area of a light source region of a light emitting part is present in a region Rin, and 60% or more of the area of a light receiving region of a light receiving part is present in a region Rout. ## Claims ### Claim 1 An optical density measuring apparatus comprising: a light emitting part; a light receiving part; and a light guiding part for guiding light from the light emitting part to the light receiving part, wherein a shape of at least a part of an inner surface of the light guiding part is composed of a figure of a part of an ellipsoid E, and a shape of at least a part of another portion of the inner surface of the light guiding part is composed of a figure of a part of a plane or a quadric surface, and when: an ellipse having a maximum area in a cross-section of the ellipsoid E is defined as an ellipse Ec, and an ellipsoid that passes through two focal points Fa and Fb of the ellipse Ec and has a minimum volume having a scaling relationship with the ellipsoid E without being rotated is defined as an ellipsoid Ein; a region included in the ellipsoid Ein is defined as a region Rin; and a region inside the ellipsoid E and not included in the ellipsoid Ein is defined as a region Rout; 60% or more of an area of a light source region of the light emitting part is present in the region Rin, and 60% or more of an area of a light receiving region of the light receiving part is present in the region Rout. ### Claim 2 (depends on 1) The optical density measuring apparatus according to claim 1, wherein all of the area of the light source region of the light emitting part is present in the region Rin, and all of the area of the light receiving region of the light receiving part is present in the region Rout. ### Claim 3 (depends on 1) The optical density measuring apparatus according to claim 1, wherein the plane or the quadric surface passes through a vicinity of one focal point of the ellipse Ec. ### Claim 4 (depends on 1) The optical density measuring apparatus according to claim 1, wherein the light receiving part is located near an edge of the ellipsoid E. ### Claim 5 (depends on 1) The optical density measuring apparatus according to claim 1, wherein an angle between an elliptical symmetry plane present at a center of a major axis of the ellipsoid E and a portion where the light guiding part is connected to the plane or the quadric surface is 1° or more. ### Claim 6 (depends on 1) The optical density measuring apparatus according to claim 1, wherein a ratio a/b of a long radius a to a short radius b of the ellipse Ec is 1.2 or more. ### Claim 7 (depends on 3) The optical density measuring apparatus according to claim 3, wherein the vicinity is a region at a distance of LE/4 or less from the one focal point when LE is a maximum length of the ellipsoid E. ### Claim 8 (depends on 1) The optical density measuring apparatus according to claim 1, wherein Ls≥(LE/50) when Ls is a maximum length of the light source region and LE is a maximum length of the ellipsoid E. ### Claim 9 (depends on 1) The optical density measuring apparatus according to claim 1, wherein Ld≥(LE/50) when Ld is a maximum length of the light receiving region and LE is a maximum length of the ellipsoid E. ### Claim 10 (depends on 1) The optical density measuring apparatus according to claim 1, wherein an identical holding part holds the light emitting part and the light receiving part. ### Claim 11 (depends on 1) The optical density measuring apparatus according to claim 1, further comprising an auxiliary reflector composed of a figure different from the ellipsoid E. ### Claim 12 (depends on 11) The optical density measuring apparatus according to claim 11, wherein the auxiliary reflector is present in the region Rin. ### Claim 13 (depends on 1) The optical density measuring apparatus according to claim 1, wherein the light emitting part is a plane light source. ### Claim 14 (depends on 1) The optical density measuring apparatus according to claim 1, wherein the ellipsoid E is a spheroid. ### Claim 15 (depends on 1) The optical density measuring apparatus according to claim 1, wherein the shape of at least the part of another portion of the inner surface of the light guiding part is a plane. ### Claim 16 (depends on 1) The optical density measuring apparatus according to claim 1, wherein the shape of at least the part of another portion of the inner surface of the light guiding part is a sphere. ### Claim 17 (depends on 1) The optical density measuring apparatus according to claim 1, wherein two or more reflection surfaces composed of a figure of a part of a plane or a quadric surface are connected to a symmetry plane of the ellipsoid E. ### Claim 18 (depends on 17) The optical density measuring apparatus according to claim 17, wherein an angle formed by a part at which the two reflection surfaces are connected is 10° or more and is 90° or less. ### Claim 19 An optical density measuring apparatus comprising: a light emitting part; a light receiving part; and a light guiding part for guiding light from the light emitting part to the light receiving part, wherein a shape of at least a part of an inner surface of the light guiding part is composed of a figure of a part of an ellipsoid E, and a shape of at least a part of another portion of the inner surface of the light guiding part is composed of a figure of a part of a plane or a quadric surface, and when: an ellipse having a maximum area in a cross-section of the ellipsoid E is defined as an ellipse Ec, and an ellipsoid that passes through two focal points Fa and Fb of the ellipse Ec and has a minimum volume having a scaling relationship with the ellipsoid E without being rotated is defined as an ellipsoid Ein; a region included in the ellipsoid Ein is defined as a region Rin; and a region inside the ellipsoid E and not included in the ellipsoid Ein is defined as a region Rout; the center of gravity of the light source region or a peak point of luminance is defined as a point Gin, the center of gravity of the light receiving region is defined as a point Gout, the point Gin is present in the region Rin, and the point Gout is present in the region Rout. ### Claim 20 An optical density measuring apparatus comprising: a light emitting part; a light receiving part; and a light guiding part for guiding light from the light emitting part to the light receiving part, wherein a shape of at least a part of an inner surface of the light guiding part is composed of a figure of a part of an ellipsoid E, and a shape of at least a part of another portion of the inner surface of the light guiding part is composed of a figure of a part of a plane or a quadric surface, and when: an ellipse having a maximum area in a cross-section of the ellipsoid E is defined as an ellipse Ec, and an ellipsoid that passes through two focal points Fa and Fb of the ellipse Ec and has a minimum volume having a scaling relationship with the ellipsoid E without being rotated is defined as an ellipsoid Ein; a region included in the ellipsoid Ein is defined as a region Rin; a region inside the ellipsoid E and not included in the ellipsoid Ein is defined as a region Rout; 60% or more of an area of a light source region of the light emitting part is present in the region Rout, and 60% or more of an area of a light receiving region of the light receiving part is present in the region Rin.