Patent US4699831A successfully refreshed from Google Patents.
Patent US5883744A successfully refreshed from Google Patents.
US5883744A
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Chromatic aberration correcting element and its application
Assignee: Pentax Corp
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Filing: 1997-02-18
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Granted: 1999-03-16
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Expires: 2017-02-18
Abstract
Abstract A chromatic aberration correcting element that is a simple lens having at least one aspheric surface, the radius of curvature of which increases from the optical axis toward the periphery. At least one of the surfaces is formed as a diffraction lens surface that consists of annular segments that shift discretely in a direction in which the lens thickness increases as a function of the distance from the optical axis. Also disclosed is a chromatic aberration correcting device having annular segments formed in steps on either a light entrance face or a light exit face or both. The annular segments are composed of planes perpendicular to and concentric with the optical axis.
Inventors
- 👤 Koichi Maruyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 13:14
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/18; G02B5/1876; G02B5/189; G02B5/1895; G02B27/00; G02B27/0025; G02B27/0037; G02B27/42; G02B27/4233; G02B27/4238; G02B3/00; G02B3/02; G02B3/04; G02B3/08; G11; G11B; G11B7/00; G11B7/12; G11B7/135; G11B7/1353; G11B7/1372; G11B7/1374; G11B7/1378
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
49 words
A lens element having a diffractive surface, said diffractive surface being formed to correct simultaneously chromatic aberration and spherical aberration generated by said lens element, wherein said diffractive surface has a convex aspheric shape macroscopically and has a radius of curvature that increases with distance from an optical axis.
Claim 2
Dependent Claim
49 words
A lens element having a diffractive surface, said diffractive surface being formed to correct simultaneously chromatic aberration and spherical aberration generated by said lens element, wherein said diffractive surface has a convex aspheric shape macroscopically and has a radius of curvature that increases with distance from an optical axis.
Claim 3
Dependent Claim
81 words
A lens element having a diffractive surface, said diffractive surface being formed to correct simultaneously chromatic aberration and spherical aberration generated by said lens element, wherein said diffractive surface has a convex aspheric shape macroscopically and has a radius of curvature that increases with distance from an optical axis and wherein said diffractive surface of said lens element comprises annular steps formed on a first surface of said lens element and each of said annular steps has an aspheric annular surface.
Claim 4
Dependent Claim
81 words
A lens element having a diffractive surface, said diffractive surface being formed to correct simultaneously chromatic aberration and spherical aberration generated by said lens element, wherein said diffractive surface has a convex aspheric shape macroscopically and has a radius of curvature that increases with distance from an optical axis and wherein said diffractive surface of said lens element comprises annular steps formed on a first surface of said lens element and each of said annular steps has an aspheric annular surface.
Claim 5
Dependent Claim
85 words
A lens element as claimed in claim 2, wherein the shape of said diffractive surface is defined by the following equation: ##EQU12## where X(h) is the sag of said diffractive surface, h is the radial distance of a point on said diffractive surface from the optical axis, r is the radius of curvature of the vertex of the aspheric surface, N is the number of the step, K is the conic constant, A4, A6, A8 and A10 are aspheric coefficients, and Δ N are constants.
Claim 6
Dependent Claim
45 words
A lens element as claimed in claim 1, wherein said diffractive surface comprises annular steps, and a thickness of said lens element decreases with distance from an optical axis except at transition points of said annular steps, the thickness increasing abruptly at said transition points.
Claim 7
Dependent Claim
64 words
A lens element as claimed in claim 4, wherein said lens element satisfies the following relationship: 0.8≦t(n-1)/λ≦10 where λ is the wavelength of light being corrected by said lens element, t is the shift amount in the optical axis direction at a corresponding one of said transition points, and n is the refractive index of the medium of which said lens element is made.
Claim 8
Dependent Claim
29 words
A lens element as claimed in claim 5, wherein said diffractive surface has a greater curvature than a second surface of said lens element which opposes said diffractive surface.
Claim 9
Dependent Claim
25 words
A lens element as claimed in claim 1, wherein said diffractive surface has a lesser curvature than a second surface which opposes said diffractive surface.
Claim 10
Dependent Claim
29 words
A lens element as claimed in claim 3, wherein each of said aspheric annular surfaces has a curvature different than the curvatures of other ones of said annular surfaces.
Claim 11
Dependent Claim
24 words
A lens element as claimed in claim 8, wherein each of said aspheric annular surfaces is rotationally symmetrical with respect to the optical axis.
Claim 12
Dependent Claim
22 words
A lens element as claimed in claim 4, wherein a second surface which opposes said diffractive surface is a continuous aspheric surface.
Claim 13
Dependent Claim
36 words
A lens element as claimed in claim 1, wherein said diffractive surface of said lens element comprises a plurality of ring shaped surfaces, and a second surface of said lens element is a continuous aspheric surface.
Claim 14
Dependent Claim
64 words
A lens element as claimed in claim 4, wherein heights of said transition points from the optical axis are defined by the following relationship: N=INT(Ah.sup.2 +Bh.sup.4 +C) where N is an integer designating the number for the annual step as counted from the optical axis, h is the height of said transition points from the optical axis, and A, B, and C are constants.
Claim 15
Dependent Claim
69 words
A lens element as claimed in claim 1, wherein the shape of said diffractive surface is defined by the following equation: X(h)=ΔN where X(h) is the sag of said diffractive surface, h is the radial distance of a point on said diffractive surface from the optical axis, and ΔN=D*N where D is a constant and N is the number for the annual step as counted from the optical axis.
Claim 16
Dependent Claim
71 words
A lens element having a diffractive surface, said diffractive surface being formed to correct simultaneously chromatic aberration and spherical aberration generated by said lens element, wherein said diffractive surface has a convex aspheric shape macroscopically and has a radius of curvature that increases with distance from an optical axis, and wherein said diffractive surface has a greater curvature than a second surface of said lens element which opposes said diffractive surface.
Claim 17
Dependent Claim
71 words
A lens element having a diffractive surface, said diffractive surface being formed to correct simultaneously chromatic aberration and spherical aberration generated by said lens element, wherein said diffractive surface has a convex aspheric shape macroscopically and has a radius of curvature that increases with distance from an optical axis, and wherein said diffractive surface has a greater curvature than a second surface of said lens element which opposes said diffractive surface.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 2002-03-15 | 2002-09-14 | 2003-03-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-03-15 | 2006-09-14 | 2007-03-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-03-15 | 2010-09-14 | 2011-03-16 | $7700.00 | Window Closed / Lapsed |