Optical imaging lens system
This invention provides an optical imaging lens system in order from an object side to an image side including: a first lens element with positive refractive power having a convex object-side surface and a concave image-side surface, a second lens element with negative refractive power having a convex object-side surface and a concave image-side surface, a third lens element with positive refractive power, and a fourth lens element having a concave image-side surface, and at least one of the object-side and image-side surfaces thereof being aspheric; wherein the optical imaging lens system further comprises an aperture stop and an electronic sensor on which an object is imaged, and the aperture stop is positioned between an object and the first lens element; wherein there are four lens elements with refractive power. By such arrangement, total track length and photosensitivity of the optical imaging lens system can be effectively reduced while retaining high image quality.
1. An optical imaging lens system, in order from an object side to an image side comprising:
a first lens element with positive refractive power having a convex object-side surface and a concave image-side surface, wherein the portion of the object-side surface of the first lens element in proximity to the optical axis is convex and the portion of the image-side surface of the first lens element in proximity to the optical axis is concave;
a second lens element with negative refractive power having a convex object-side surface and a concave image-side surface;
a third lens element with positive refractive power; and
a fourth lens element having a concave image-side surface, and at least one of the object-side and image-side surfaces thereof being aspheric;
wherein the optical imaging lens system further comprises an aperture stop and an electronic sensor on which an object is imaged, and the aperture stop is positioned between an object and the first lens element;
wherein there are four lens elements with refractive power;
wherein a focal length of the optical imaging lens system is f, a focal length of the third lens element is f 3 , a focal length of the fourth lens element is f 4 , an on-axis spacing between the first lens element and the second lens element is T 12 , an on-axis spacing between the second lens element and the third lens element is T 23 , a distance on the optical axis between the aperture stop and the electronic sensor is SL, a distance on the optical axis between the object-side surface of the first lens element and the electronic sensor is TTL, and they satisfy the relation:
0 <f/f 3<0.9;
| f/f 4|<0.75;
0 <T 12 /T 23<0.27; and
0.9 <SL/TTL< 1.2.
2. The optical imaging lens system according to claim 1 , wherein at least one inflection point is formed on at least one surface of the object-side and image-side surfaces of the fourth lens element, and the fourth lens element is made of plastic.
3. The optical imaging lens system according to claim 2 , wherein the third lens element has a concave object-side surface and a convex image-side surface, and a refractive index of the first lens element is N 1 , and it satisfies the relation:
1.4 <N 1<1.6.
4. The optical imaging lens system according to claim 3 , wherein a radius of curvature of the image-side surface of the second lens element is R 4 , a radius of curvature of the object-side surface of the second lens element is R 3 , and they satisfy the relation:
0 <R 4 /R 3<0.3.
5. The optical imaging lens system according to claim 3 , wherein a focal length of the optical imaging lens system is f, a focal length of the third lens element is f 3 , and they satisfy the relation:
0 <f/f 3<0.75.
6. The optical imaging lens system according to claim 5 , wherein the fourth lens element has negative refractive power and a convex object-side surface.
7. The optical imaging lens system according to claim 6 , wherein a focal length of the optical imaging lens system is f, a focal length of the fourth lens element is f 4 , and they satisfy the relation:
| f/f 4|<0.5.
8. The optical imaging lens system according to claim 6 , wherein a vertical distance between a maximum effective diameter position on the image-side surface of the third lens element and the optical axis is Y 32 , a distance in parallel with the optical axis from the maximum effective diameter position on the image-side surface of the third lens element to the on-axis vertex on the image-side surface of the third lens element is SAG 32 , and they satisfy the relation:
0.5 <SAG 32 /Y 32<0.8.
9. The optical imaging lens system according to claim 6 , wherein a focal length of the optical imaging lens system is f, a focal length of the first lens element is f 1 , and they satisfy the relation:
1.2 <f/f 1<1.7.
10. The optical imaging lens system according to claim 6 , wherein a focal length of the optical imaging lens system is f, a focal length of the third lens element is f 3 , and they satisfy the relation:
0 <f/f 3<0.5.
11. The optical imaging lens system according to claim 6 , wherein an Abbe number of the first lens element is V 1 , an Abbe number of the second lens element is V 2 , and they satisfy the relation:
30 <V 1 −V 2<42.
12. The optical imaging lens system according to claim 11 , wherein a radius of curvature of the object-side surface of the first lens element is R 1 , a radius of curvature of the image-side surface of the first lens element is R 2 , and they satisfy the relation:
0 <R 1 /R 2<0.2.
13. The optical imaging lens system according to claim 1 , wherein a distance on the optical axis between the object-side surface of the first lens element and the electronic sensor is TTL, half of the diagonal length of the effective pixel area of the electronic sensor is ImgH, and they satisfy the relation:
TTL/ImgH< 1.95.
14. An optical imaging lens system, in order from an object side to an image side comprising:
a first lens element with positive refractive power having a convex object-side surface and a concave image-side surface, wherein the portion of the object-side surface of the first lens element in proximity to the optical axis is convex and the portion of the image-side surface of the first lens element in proximity to the optical axis is concave;
a second lens element with negative refractive power having a convex object-side surface and a concave image-side surface;
a third lens element with positive refractive power having a concave object-side surface and a convex image-side surface, and at least one of the object-side and image-side surfaces thereof being aspheric; and
a fourth lens element with negative refractive power having a convex object-side surface and a concave image-side surface, and at least one of the object-side and image-side surfaces thereof being aspheric;
wherein the optical imaging lens system further comprises an aperture stop and an electronic sensor on which an object is imaged, and the aperture stop is positioned between an object and the first lens element;
wherein there are four lens elements with refractive power;
wherein a radius of curvature of the image-side surface of the second lens element is R 4 , a radius of curvature of the object-side surface of the second lens element is R 3 , a distance on the optical axis between the aperture stop and the electronic sensor is SL, a distance on the optical axis between the object-side surface of the first lens element and the electronic sensor is TTL, an on-axis spacing between the first lens element and the second lens element is T 12 , an on-axis spacing between the second lens element and the third lens element is T 23 , and they satisfy the relation:
0 <R 4 /R 3<0.3;
0.9 <SL/TTL< 1.2; and
0 <T 12 /T 23<0.6.
15. The optical imaging lens system according to claim 14 , wherein at least one inflection point is formed on at least one surface of the object-side and image-side surfaces of the fourth lens element, and the fourth lens element is made of plastic.
16. The optical imaging lens system according to claim 15 , wherein a focal length of the optical imaging lens system is f, a focal length of the third lens element is f 3 , and they satisfy the relation:
0 <f/f 3<0.9.
17. The optical imaging lens system according to claim 16 , wherein a focal length of the optical imaging lens system is f, a focal length of the fourth lens element is f 4 , and they satisfy the relation:
| f/f 4|<0.5.
18. The optical imaging lens system according to claim 16 , wherein an on-axis spacing between the first lens element and the second lens element is T 12 , an on-axis spacing between the second lens element and the third lens element is T 23 , and they satisfy the relation:
0 <T 12 /T 23<0.27.
19. The optical imaging lens system according to claim 16 , wherein an Abbe number of the first lens element is V 1 , an Abbe number of the second lens element is V 2 , and they satisfy the relation:
30 <V 1 −V 2<42.
20. The optical imaging lens system according to claim 15 , wherein a focal length of the optical imaging lens system is f, a focal length of the third lens element is f 3 , and they satisfy the relation:
0 <f/f 3<0.75.