Imaging lens
A low-cost, compact and low-profile imaging lens with relatively high brightness, which provides a wide field of view (full field of view: about 90 degrees) and corrects aberrations properly. Designed for a solid-state image sensor, it includes elements arranged in the following order from an object side to an image side: an aperture stop, a first positive (refractive power) lens, a second negative lens having a concave image-side surface, a third positive lens having a convex image-side surface, a fourth lens as a meniscus double-sided aspheric lens having a convex object-side surface near an optical axis, a fifth negative lens as a double-sided aspheric lens having a concave image-side surface near the optical axis, and a conditional expression (1) below is satisfied: | r 1|>| r 2| (1) where r1: curvature radius of the object-side surface of the first lens r2: curvature radius of the image-side surface of the first lens.
1. An imaging lens for a solid-state image sensor in which elements are arranged in order from an object side to an image side, comprising:
an aperture stop;
a first lens with positive refractive power;
a second lens as a meniscus lens with negative refractive power having a concave surface on the image side;
a third lens with positive refractive power having a convex surface on the image side;
a fourth lens as a meniscus double-sided aspheric lens having a convex surface on the object side near an optical axis; and
a fifth lens as a double-sided aspheric lens with negative refractive power having a concave surface on the image side near the optical axis,
wherein a conditional expression (1) below is satisfied:
| r 1 |>|r 2| (1)
where
r1: curvature radius of the object-side surface of the first lens, and
r2: curvature radius of the image-side surface of the first lens.
2. The imaging lens according to claim 1 ,
wherein a conditional expression (2) below is satisfied:
0.9 <ih/f< 1.1 (2)
where
f: focal length of an overall optical system of the imaging lens, and
ih: maximum image height.
3. The imaging lens according to claim 1 ,
wherein a conditional expression (3) below is satisfied:
2.20 <|r 1 /r 2|<8.20 (3)
where
r1: curvature radius of the object-side surface of the first lens, and
r2: curvature radius of the image-side surface of the first lens.
4. The imaging lens according to claim 1 ,
wherein a conditional expression (4) below is satisfied:
−1.50 <f 2 /f<− 1.00 (4)
where
f: focal length of an overall optical system of the imaging lens, and
f2: focal length of the second lens.
5. The imaging lens according to claim 1 ,
wherein a conditional expression (5) below is satisfied:
0.70 <f 3 /f< 1.50 (5)
where
f: focal length of an overall optical system of the imaging lens, and
f3: focal length of the third lens.
6. The imaging lens according to claim 1 ,
wherein the aspheric surfaces of the fourth lens have a pole-change point in a position off the optical axis.
7. The imaging lens according to claim 1 ,
wherein the aspheric surfaces of the fifth lens have a pole-change point in a position off the optical axis.
8. The imaging lens according to claim 1 ,
wherein a conditional expression (6) below is satisfied:
0.6 <TTL/ 2 ih< 1.0 (6)
where
TTL: distance on the optical axis from the aperture stop to an image plane without a filter, and
ih: maximum image height.
9. The imaging lens according to claim 2 ,
wherein a conditional expression (4) below is satisfied:
−1.50 <f 2 /f<− 1.00 (4)
where
f2: focal length of the second lens.
10. The imaging lens according to claim 2 ,
wherein a conditional expression (5) below is satisfied:
0.70 <f 3 /f< 1.50 (5)
where
f3: focal length of the third lens.
11. The imaging lens according to claim 2 ,
wherein the aspheric surfaces of the fourth lens have a pole-change point in a position off the optical axis.
12. The imaging lens according to claim 2 ,
wherein the aspheric surfaces of the fifth lens have a pole-change point in a position off the optical axis.
13. The imaging lens according to claim 2 ,
wherein a conditional expression (6) below is satisfied:
0.6 <TTL/ 2 ih< 1.0 (6)
where
TTL: distance on the optical axis from the aperture stop to an image plane without a filter, and
ih: maximum image height.
14. An imaging lens for a solid-state image sensor in which elements are arranged in order from an object side to an image side, comprising:
a first lens with positive refractive power having a convex surface on the object side;
a second lens having a convex surface on the object side;
a third lens;
a fourth lens as a double-sided aspheric lens having a concave surface on the image side near an optical axis; and
a fifth lens as a double-sided aspheric lens having a concave surface on the image side near the optical axis,
wherein a conditional expression (2) below is satisfied:
0.9 <ih/f< 1.1 (2)
where
f: focal length of an overall optical system of the imaging lens, and
ih: maximum image height.
15. The imaging lens according to claim 14 ,
wherein a conditional expression (1) below is satisfied:
| r 1 |>|r 2| (1)
where
r1: curvature radius of the object-side surface of the first lens, and
r2: curvature radius of the image-side surface of the first lens.
16. The imaging lens according to claim 14 ,
wherein conditional expressions (4) and (5) below are satisfied:
−1.50 <f 2 /f<− 1.00 (4)
0.70 <f 3 /f< 1.50 (5)
where
f: focal length of an overall optical system of the imaging lens,
f2: focal length of the second lens, and
f3: focal length of the third lens.
17. The imaging lens according to claim 14 ,
wherein the third lens with positive refractive power has a convex surface on the image side, and the fourth lens is a meniscus lens having a concave surface on the image side near the optical axis, and having a pole-change point in a position off the optical axis on the aspheric surfaces of the fourth lens.
18. The imaging lens according to claim 14 ,
wherein the fifth lens is a meniscus lens having a concave surface on the image side near the optical axis, and having a pole-change point in a position off the optical axis on the aspheric surfaces of the fifth lens.
19. An imaging lens for a solid-state image sensor in which elements are arranged in order from an object side to an image side, comprising:
an aperture stop;
a first lens with positive refractive power having a convex surface on the object side;
a second lens having a convex surface on the object side;
a third lens;
a fourth lens as a double-sided aspheric lens with positive refractive power having a concave surface on the image side near an optical axis; and
a fifth lens as a double-sided aspheric lens having a concave surface on the image side near the optical axis,
wherein the fourth lens has a weaker refractive power than the first lens, the second lens, the third lens, and the fifth lens.
20. The imaging lens according to claim 1 , wherein conditional expressions (2) and (6) below are satisfied:
0.9 <ih/f< 1.1 (2)
0.6 <TTL/ 2 ih< 1.0 (6)
where
f: focal length of an overall optical system of the imaging lens,
TTL: distance on the optical axis from the aperture stop to an image plane without a filter, and
ih: maximum image height.