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US 7,623,307 B2Granted
Imaging lens
AssigneeFujinon Corporation
InventorTakayuki Noda
Life of this patent
Estimating the term…
Abstract
An imaging lens is provided and includes: in order from an object side of the imaging lens, a first lens having a positive refractive power; a second lens having one of a positive refractive power and a negative refractive power; and a third lens that corrects for aberration. At least one of the first and second lenses has a diffractive optical surface, the diffractive optical surface having twenty or less orbicular gratings in a range to pass an effective light ray.
Claims20
An imaging lens comprising:
- in order from an object side of the imaging lens,
- a first lens having a positive refractive power;
- a second lens having one of a positive refractive power and a negative refractive power;
- a third lens that corrects for aberration,
- wherein at least one of the first and second lenses has a diffractive optical surface, the diffractive optical surface having twenty or less orbicular gratings in a range to pass an effective light ray;
- and
- an aperture stop located on an object side of the first lens or between the first and second lenses, wherein said diffractive optical surface is provided on a lens arranged closest to said aperture stop.
4 more elements
An imaging lens comprising:
- in order from an object side of the imaging lens,
- a first lens having a positive refractive power;
- a second lens having one of a positive refractive power and a negative refractive power;
- a third lens that corrects for aberration,
- wherein at least one of the first and second lenses has a diffractive optical surface, the diffractive optical surface having twenty or less orbicular gratings in a range to pass an effective light ray;
- and
- an aperture stop on an object side of the first lens or between the first and second lenses,
- wherein a lens arranged closest to the aperture stop has the diffractive optical surface on a lens surface having, in the vicinity of the optical axis, a radius of curvature which is larger in absolute value than a radius of curvature of an opposite lens surface of the lens.
5 more elements
An imaging lens comprising:
- in order from an object side of the imaging lens,
- a first lens having a positive refractive power;
- a second lens having one of a positive refractive power and a negative refractive power;
- and
- a third lens that corrects for aberration,
- wherein at least one of the first and second lenses has a diffractive optical surface, the diffractive optical surface having twenty or less orbicular gratings in a range to pass an effective light ray, and
- wherein said orbicular gratings are recessed inward of a basic surface of the lens having said diffractive optical surface.
4 more elements
An imaging lens comprising:
- in order from an object side of the imaging lens,
- a first lens having a positive refractive power;
- a second lens having one of a positive refractive power and a negative refractive power;
- and
- a third lens that corrects for aberration,
- wherein at least one of the first and second lenses has a diffractive optical surface, the diffractive optical surface having twenty or less orbicular gratings in a range to pass an effective light ray, and
- wherein said orbicular gratings are structured so as to relieve on-axis chromatic aberration at longer wavelength.
4 more elements
Dependencies are inferred from the claim text.