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US 7,443,611 B2Granted
Imaging lens
AssigneeFujinon Corporation
InventorYoshikazu Shinohara
Life of this patent
Estimating the term…
Abstract
An imaging lens is provided and includes: a first lens of a positive lens; a second lens of a negative lens whose concave surface faces to an image side of the second lens; a third lens of a positive lens, whose both surfaces are aspheric, having a concave surface facing to an object side of the third lens; and a fourth lens of a meniscus lens, whose both surfaces are aspheric, having a convex surface facing to the object side near the optical axis, the lenses being arranged in this order from an object side, the first imaging lens satisfying the conditional expressions specified in the specification.
Claims29
An imaging lens comprising:
- in order from an object side of the imaging lens,
- a first lens of a positive lens;
- a second lens of a negative lens having a concave surface on an image side thereof;
- a third lens of a positive lens having a concave surface on an object side thereof, wherein both surfaces of the third lens are aspheric;
- and
- a fourth lens of a meniscus lens having a convex surface on an object side thereof and near an optical axis, wherein both surfaces of the fourth lens are aspheric,
- the imaging lens satisfying conditional expressions (1) to (6):
- 0.3<|f1/f2|<0.8 (1)
- νdG1−νdG2>25 (2)
- |A1|<1.5×10−5×1/° C. (3)
- |A2|<1.5×10−5×1/° C. (4)
- |A3|>1.5×10−5×1/° C. (5)
- |A4|>1.5×10−5×1/° C. (6)
- wherein
- f1 represents a focal length of the first lens,
- f2 represents a focal length of the second lens,
- νdG1 represents Abbe number of the first lens,
- νdG2 represents Abbe number of the second lens,
- A1 represents a linear coefficient of expansion of the first lens,
- A2 represents a linear coefficient of expansion of the second lens,
- A3 represents a linear coefficient of expansion of the third lens, and
- A4 represents a linear coefficient of expansion of the fourth lens.
19 more elements
An imaging lens comprising:
- in order from an object side of the imaging lens,
- a first lens of a positive lens made of a glass material;
- a second lens of a negative lens made of a glass material and having a concave surface on an image side thereof;
- a third lens of a positive lens made of a plastic material and having a concave surface on an object side thereof, wherein both surfaces of the third lens are aspheric;
- and
- a fourth lens of a meniscus lens made of a plastic material and having a convex surface on an object side thereof and near an optical axis, wherein both surfaces of the fourth lens are aspheric,
- the imaging lens satisfying conditional expressions (1) to (2):
- 0.3<|f1/f2|<0.8 (1)
- νdG1−νdG2>25 (2)
- wherein
- f1 represents a focal length of the first lens,
- f2 represents a focal length of the second lens,
- νdG1 represents Abbe number of the first lens, and
- νdG2 represents Abbe number of the second lens.
11 more elements
An imaging lens comprising:
- in order from an object side of the imaging lens,
- a first lens of a positive lens;
- a second lens of a negative lens having a concave surface on an image side thereof;
- a third lens of a positive lens having a concave surface on an object side thereof, wherein both surfaces of the third lens are aspheric;
- and
- a fourth lens of a meniscus lens having a convex surface on an object side thereof and near an optical axis, wherein both surfaces of the fourth lens are aspheric,
- the imaging lens satisfying conditional expressions (1) and (2):
- 0.3<|f1/f2|<0.8 (1)
- νdG1−νdG2>25 (2)
- wherein
- f1 represents a focal length of the first lens,
- f2 represents a focal length of the second lens,
- νdG1 represents Abbe number of the first lens,
- νdG2 represents Abbe number of the second lens, and
- wherein said first and second lenses have relatively small linear coefficients of expansion, and said third and fourth lenses have linear coefficients of expansion which are larger than the liner coefficients of expansion of said first and second lenses.
12 more elements
An imaging lens comprising:
- in order from an object side of the imaging lens,
- a first lens of a positive lens;
- a second lens of a negative lens having a concave surface on an image side thereof;
- a third lens of a positive lens having a concave surface on an object side thereof, wherein both surfaces of the third lens are aspheric;
- and
- a fourth lens of a meniscus lens having a convex surface on an object side thereof and near an optical axis, wherein both surfaces of the fourth lens are aspheric,
- the imaging lens satisfying conditional expressions (1) and (2):
- 0.3<|f1/f2|<0.8 (1)
- νdG1−νdG2>25 (2)
- wherein
- f1 represents a focal length of the first lens,
- f2 represents a focal length of the second lens,
- νdG1 represents Abbe number of the first lens, and
- νdG2 represents Abbe number of the second lens, and
- wherein liner coefficients of expansion of said first and second lenses are smaller than linear coefficients of expansion of said third and fourth lenses.
12 more elements
Dependencies are inferred from the claim text.