# US 8,786,965 B2 · Die processing method, die, objective lens, and optical pick-up device > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,786,965 B2 - Document ID: US8786965B2 - Status: Granted - Kind: B2 - Application number: 13/498,575 - Filed: 2010-08-17 - Published: 2012-07-19 - Granted: 2014-07-22 - Earliest claimed: 2009-09-30 - Assignees: Konica Minolta Opto, Inc. - Applicants: Kenichi Ishii; Kyu Takada - Inventors: Kenichi Ishii; Kyu Takada - Web page: https://patentgrep.com/patent/US8786965B2 ## CPC - G11B 7/1374: Objective lenses {(optical objectives per se G02B9/00)} - B23B 1/00: Methods for turning or working essentially requiring the use of turning-machines; Use of auxiliary equipment in connection with such methods - B23B 27/005: {Geometry of the chip-forming or the clearance planes, e.g. tool angles (B23B27/141 and B23B27/22 take precedence)} - B23B 27/06: Profile cutting tools, i.e. forming-tools - B29D 11/00009: {Production of simple or compound lenses} - B29D 11/0048: {Moulds for lenses (moulds for plastic articles in general B29C33/00)} - G02B 5/1895: {such optical elements having dioptric power} - G11B 7/1353: Diffractive elements, e.g. holograms or gratings {(diffraction gratings per se G02B5/18; holograms per se G02B5/32; grating systems G02B27/44)} - B29C 33/424: {Moulding surfaces provided with means for marking or patterning (for injection moulding B29C45/372)} - G11B 7/13922: {passive} - G11B 7/22: Apparatus or processes for the manufacture of optical heads, e.g. assembly - G11B 2007/0006: {adapted for scanning different types of carrier, e.g. CD & DVD} - G11B: INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D9/00; recording or playback apparatus using mechanically marked tape, e.g. punched paper tape, or using unit records, e.g. punched or magnetically marked cards G06K; transferring data from one type of record carrier to another G06K1/18; circuits for coupling output of reproducer to radio receiver H04B1/20; gramophone pick-ups or like acoustic electromechanical transducers or circuits therefor H04R) - B23B: TURNING; BORING (arrangements for copying or controlling B23Q) - B29D: PRODUCING PARTICULAR ARTICLES FROM PLASTICS OR FROM SUBSTANCES IN A PLASTIC STATE (making granules B29B9/00; making preforms B29B11/00) - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - B29C: SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING (making preforms B29B11/00; making laminated products by combining previously unconnected layers which become one product whose layers will remain together B32B37/00 - B32B41/00) ## Abstract A method for processing a material for a die for molding an objective lens which is formed with a multilevel structure on the curved surface thereof, wherein the transfer surface of the objective lens is cut by a tool having a cutting face, the outline of which includes a linear first edge portion, a linear second edge portion extending in a direction which intersects the first edge portion at an acute angle thereto, and a third edge portion which joins the ends of the first and second edge portions, while the die material is rotated around the axis thereof, in a state in which at least the first edge portion and the second edge portion of the tool is inclined with respect to the axis and while the tool is moved only in the axial direction and in the direction which intersects the axis. ## Claims ### Claim 1 An objective lens used for an optical pick-up device compatible with different types of optical disks and to focus a light flux onto an information recording surface of each of the optical disks, comprising: at least one optical surface including an optical path difference providing structure, wherein the objective lens is a plastic lens, wherein the optical path difference providing structure includes ring-shaped zones, wherein on a cross section of the objective lens in the optical axis direction, a first slope which is closer to the optical axis in the part of ring-shaped zones inclines so as to deviate from the optical axis as the first slope proceeds to the tip of the part of ring-shaped zones and a second slope which is farther from the optical axis in the part of ring-shaped zones is parallel to the optical axis or inclines so as to get close to the optical axis as the second slope proceeds to the tip of the part of ring-shaped zones, wherein following formula is satisfied: 0°≦θ2′≦15° Formula (7) where θ2′ is an acute angle between the optical axis and the second slope. ### Claim 2 (depends on 1) The objective lens of claim 1, wherein on the cross section of the objective lens in the optical axis direction, an acute slope angle θ1′ between the optical axis and the first slope is larger than θ2′ in the part of the ring-shaped zones. ### Claim 3 (depends on 2) The objective lens of claim 2, wherein following is satisfied: 15°≦θ1′≦35° Formula (6). ### Claim 4 (depends on 3) The objective lens of claim 3, wherein a following formula is satisfied: 1°≦θ2′≦15° Formula (8). ### Claim 5 (depends on 1) The objective lens of claim 1, wherein on the cross section of the objective lens in the optical axis direction, an acute slope angle θ1′ between the optical axis and the first slope is equal to or nearly equal to θ2′ in the part of the ring-shaped zones. ### Claim 6 (depends on 5) The objective lens of claim 5, wherein a following formula is satisfied: 10°≦θ1′≦20° Formula (9). ### Claim 7 (depends on 1) The objective lens of claim 1, wherein the optical path difference providing structure comprises two basic structures and the two basic structures are superimposed. ### Claim 8 (depends on 1) The objective lens of claim 1, wherein a following formula is satisfied, when a thickness of the objective lens along the optical axis and a focal length of the objective lens are set to be d (mm) and f (mm) respectively: 0.9≦d/f≦1.6 Formula (5). ### Claim 9 (depends on 1) An optical pick-up device comprising the objective lens of claim 1. ### Claim 10 (depends on 1) The objective lens of claim 1, wherein the part of ring-shaped zones comprises a terrace surface which is connecting the first slope and the second slope. ### Claim 11 (depends on 1) The objective lens of claim 1, wherein the light flux passing through the second slope does not converge onto an information recording surface of each of the optical disks.