Imaging lens
A low-cost, compact and low-profile imaging lens with relatively high brightness, which provides a wide angle of view of about 90 degrees and corrects various aberrations properly. It is designed for use in a solid-state image sensor and includes the following elements arranged in order from an object side to an image side: a first lens as a positive or negative double-sided aspheric lens having a convex object-side surface near an optical axis; an aperture stop; a positive second lens having a convex image-side surface; a negative third lens having a concave image-side surface; a positive fourth lens having a convex image-side surface; and a fifth lens as a negative meniscus lens having a concave image-side surface near the optical axis. It satisfies a conditional expression (1) below: 0.9<ih/f<1.1 (1) where f: focal length of the overall optical system of the imaging lens ih: maximum image height.
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:
a first lens as a double-sided aspheric lens with positive refractive power having convex surfaces on the object side and the image side near an optical axis;
an aperture stop;
a second lens with positive refractive power having convex surfaces on the object side and the image side near the optical axis;
a third lens as a meniscus lens with negative refractive power having a concave surface on the image side;
a fourth lens with positive refractive power having a convex surface on the image side; and
a fifth lens as a meniscus lens with negative refractive power having a concave surface on the image side near the optical axis,
wherein an angle of view is substantially 90 degrees, and
wherein a conditional expression (1) below is satisfied:
0.9<ih/f<1.1 (1)
where
f: focal length of an overall optical system of the imaging lens, and
ih: maximum image height.
2. The imaging lens according to claim 1 , wherein a conditional expression (2) below is satisfied:
0.04<|r1/r2|<2.50 (2)
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.
3. The imaging lens according to claim 1 , wherein a conditional expression (3) below is satisfied:
0.4<r6/f<0.8 (3)
where
r6: curvature radius of the image-side surface of the third lens.
4. The imaging lens according to claim 1 , wherein a conditional expression (4) below is satisfied:
1.94<|r7/r8|<3.65 (4)
where
r7: curvature radius of the object-side surface of the fourth lens
r8: curvature radius of the image-side surface of the fourth lens.
5. The imaging lens according to claim 1 , wherein a conditional expression (5) below is satisfied:
1.33<TTL/f<2.20 (5)
where
TTL: distance on the optical axis from the object-side surface of the first lens to an image plane without a filter, etc.
6. The imaging lens according to claim 1 , wherein a conditional expression (6) below is satisfied:
0.65<f2/f<1.24 (6)
where
f2: focal length of the second lens.
7. The imaging lens according to claim 2 , wherein a conditional expression (7) below is satisfied:
1.0<|r3|/f (7)
where
r3: curvature radius of the object-side surface of the second lens.
8. The imaging lens according to claim 1 , wherein a conditional expression (8) below is satisfied:
−1.6<f3/f<−1.0 (8)
where
f3: focal length of the third lens.
9. The imaging lens according to claim 2 , wherein a conditional expression (3) below is satisfied:
0.4<r6/f<0.8 (3)
where
r6: curvature radius of the image-side surface of the third lens.
10. The imaging lens according to claim 2 , wherein a conditional expression (4) below is satisfied:
1.94<|r7/r8|<3.65 (4)
where
r7: curvature radius of the object-side surface of the fourth lens
r8: curvature radius of the image-side surface of the fourth lens.
11. The imaging lens according to claim 2 , wherein a conditional expression (6) below is satisfied:
0.65<f2/f<1.24 (6)
where
f2: focal length of the second lens.
12. The imaging lens according to claim 2 , wherein a conditional expression (8) below is satisfied:
−1.6<f3/f<−1.0 (8)
where
f3: focal length of the third lens.
13. 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 as a meniscus double-sided aspheric lens with positive or negative refractive power having a convex surface on the object side near an optical axis;
an aperture stop;
a second lens with positive refractive power having a convex surface on the image side;
a third lens having a convex surface on the object side;
a fourth lens; and
a fifth lens as a meniscus lens with negative refractive power having a concave surface on the image side near the optical axis,
wherein conditional expressions (4) and (6) below are satisfied:
1.94<|r7/r8|<3.65 (4)
0.65<f2/f<1.24 (6)
where
r7: curvature radius of the object-side surface of the fourth lens,
r8: curvature radius of the image-side surface of the fourth lens,
f: focal length of an overall optical system of the imaging lens, and
f2: focal length of the second lens.
14. The imaging lens according to claim 13 , wherein the third lens is a meniscus lens with negative refractive power, and the fourth lens with positive refractive power having a convex surface on the image side.
15. The imaging lens according to claim 13 , wherein a conditional expression (1) below is satisfied:
0.9<ih/f<1.1 (1)
where
f: focal length of an overall optical system of the imaging lens, and
ih: maximum image height.
16. The imaging lens according to claim 13 , wherein a conditional expression (2) below is satisfied:
0.04<|r1/r2|<2.50 (2)
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.
17. The imaging lens according to claim 13 , wherein a conditional expression (3) below is satisfied:
0.4<r6/f<0.8 (3)
where
r6: curvature radius of the image-side surface of the third lens.
18. The imaging lens according to claim 13 , wherein a conditional expression (5) below is satisfied:
1.33<TTL/f<2.20 (5)
where
TTL: distance on the optical axis from the object-side surface of the first lens to an image plane without a filter, etc.
19. The imaging lens according to claim 16 , wherein a conditional expression (7) below is satisfied:
1.0<|r3|/f (7)
where
r3: curvature radius of the object-side surface of the second lens.
20. The imaging lens according to claim 13 , wherein a conditional expression (8) below is satisfied:
−1.6<f3/f<−1.0 (8)
where
f3: focal length of the third lens.