Endoscope objective lens
First Claim
1. An endoscope objective lens comprising, successively from the object side:
- a first lens directing its concave surface to the image side;
a second lens made of a positive meniscus lens directing its convex surface to the image side;
a third lens made of a planoconvex lens directing its convex surface to the object side; and
a stop placed between the first lens and the second lens;
wherein the following Conditional Expressional expressions (1) to (4) are satisfied;
2.00<
|f1/f|<
3.00
(1)
0.50<
|f2/f3|<
0.70
(2)
2.00<
|f1/d1-2|<
5.00
(3)
0.40<
|R2R/R2F|<
0.60
(4)and whereinf;
Focal length of the whole system,f1;
Focal length of the first lens,f2;
Focal length of the second lens,f3;
Focal length of the third lens,d1-2;
Air gap between the first lens and the second lens,R2F;
Radius of curvature of the object-side surface of the second lens,R2R;
Radius of curvature of the image-side surface of the second lens.
1 Assignment
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Accused Products
Abstract
To provide an endoscope objective lens which has a lens constitution of a relatively small number of three pieces, a short total length of lens, and various kinds of good optical performances starting with curvature of field. It is constituted of a first lens L1 directing its concave surface to the image side, a second lens L2 made of a positive meniscus lens directing its convex surface to the image side, and a third lens L3 made of a planoconvex lens directing its convex surface to the object side arranged sequentially from the object side, and a stop placed between said first lens L1 and said second lens L2. It also satisfies the following Conditional Expressions:
2.00<|f1/f|<3.00, (1)
0.50<|f2/f3|<0.70, (2)
2.00<|f1/d1-2|<5.00 , (3)
0.40<|R2R/R2F|<0.60 . (4)
Note that f is the focal length of the whole system, f1–f3 the focal lengths of the first-third lenses, respectively, d1-2 the air distance between the first lens and the second lens, R2F the radius of curvature of the object-side surface of the second lens, and R2R the radius of curvature of the image-side surface of the second lens.
60 Citations
6 Claims
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1. An endoscope objective lens comprising, successively from the object side:
-
a first lens directing its concave surface to the image side; a second lens made of a positive meniscus lens directing its convex surface to the image side; a third lens made of a planoconvex lens directing its convex surface to the object side; and a stop placed between the first lens and the second lens; wherein the following Conditional Expressional expressions (1) to (4) are satisfied;
2.00<
|f1/f|<
3.00
(1)
0.50<
|f2/f3|<
0.70
(2)
2.00<
|f1/d1-2|<
5.00
(3)
0.40<
|R2R/R2F|<
0.60
(4)and wherein f;
Focal length of the whole system,f1;
Focal length of the first lens,f2;
Focal length of the second lens,f3;
Focal length of the third lens,d1-2;
Air gap between the first lens and the second lens,R2F;
Radius of curvature of the object-side surface of the second lens,R2R;
Radius of curvature of the image-side surface of the second lens.- View Dependent Claims (2, 3, 4, 5, 6)
-
Specification