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US 7,408,725 B2Granted
Single focus lens
AssigneeFujinon Corporation
InventorKenichi Sato
Life of this patent
Estimating the term…
Abstract
A single focus lens is provided and includes: in order from an object side of the single focus lens, a first lens having positive power and having a convex surface on the object side; a second lens of a negative meniscus lens and having a concave surface of the object side on its paraxial axis; and a third lens of an aspherical lens having a convex surface on the object side on its paraxial axis. The single focus lens satisfies conditions specified in the specification.
Claims26
A single focus lens comprising:
- in order from an object side of the single focus lens,
- a first lens having positive power and having a convex surface on the object side;
- a second lens of a negative meniscus lens and having a concave surface of the object side on its paraxial axis;
- and
- a third lens of an aspherical lens having a convex surface on the object side on its paraxial axis,
- wherein the single focus lens satisfies conditions (1) to (7):
- 0.6<f1/f<1.5 (1)
- 69<νdA (2)
- 24<νdB<32 (3)
- NdA<1.55 (4)
- 1.48<NdB<1.65 (5)
- L/D<1.8 (6)
- 0.30<RA/f<0.40 (7)
- wherein
- f represents a focal length of the single focus lens;
- f1 represents a focal length of the first lens;
- νdA represents Abbe number of the first lens;
- νdB represents Abbe number of the second lens;
- NdA represents a refractive index at the d-line of the first lens;
- NdB represents a refractive index at the d-line of the second lens;
- RA represents a paraxial radius of curvature of an object-side surface of the first lens;
- L represents a distance along an optical axis between the object-side surface of the first lens and an image-forming position;
- and
- D represents a maximum image height.
21 more elements
A single focus lens comprising:
- in order from an object side of the single focus lens,
- a first lens having positive power and having a convex surface on the object side;
- a second lens of a negative meniscus lens and having a concave surface of the object aide on its paraxial axis;
- and
- a third lens of an aspherical lens having a convex surface on the object side on its paraxial axis,
- wherein the single focus lens satisfies conditions (1), (6) and (7) for compactness:
- 0.6<f1/f<1.5 (1)
- L/D<1.8 (6)
- 0.30<RA/f<0.40 (7)
- wherein
- f represents a focal length of the single focus lens;
- f1 represents a focal length of the first lens;
- RA represents a paraxial radius of curvature of an object-side surface of the first lens;
- L represents a distance along an optical axis between the object-side surface of the first lens and an image-forming position;
- and
- D represents a maximum image height.
13 more elements
A single focus lens comprising:
- in order from an object side of the single focus lens,
- a first lens having positive power and having a convex surface on the object side;
- a second lens of a negative meniscus lens and having a concave surface of the object side on its paraxial axis;
- and
- a third lens of an aspherical lens having a convex surface on the object side on its paraxial axis,
- wherein the single focus lens satisfies conditions (2)-(6):
- 69<νdA (2)
- 24<νdB<32 (3)
- NdA<1.55 (4)
- 1.48<NdB<1.65 (5)
- L/D<1.8 (6)
- wherein
- f represents a focal length of the single focus lens;
- νdA represents Abbe number of the first lens
- νdB represents Abbe number of the second lens;
- NdA represents a refractive index at the d-line of the first lens;
- NdB represents a refractive index at the d-line of the second lens;
- L represents a distance along an optical axis between the object-side surface of the first lens and an image-forming position;
- and
- D represents a maximum image height.
17 more elements
Dependencies are inferred from the claim text.