Optical system for imaging pickup
An optical system for imaging pickup includes, sequentially arranged from an object side to an image side: the first lens element with positive refractive power having a convex image-side surface, the second lens element with refractive power having a concave image-side surface, the third lens element with refractive power, the fourth lens element with refractive power having both object-side and image-side surfaces being aspheric, and the fifth lens element with negative refractive power having a concave image-side surface, and both object-side and image-side surfaces being aspheric. By such arrangements, the optical system for imaging pickup satisfies conditions related to shorten the total length and to reduce the sensitivity for use in compact cameras and mobile phones with camera functionalities.
1. An optical system for imaging pickup, sequentially arranged from an object side to an image side, comprising:
a first lens element with positive refractive power, having a convex image-side surface;
a second lens element with refractive power, having a concave image-side surface;
a third lens element with refractive power;
a fourth lens element with refractive power, having both object-side surface and image-side surface being aspheric; and
a fifth lens element with negative refractive power, having a concave image-side surface, both object-side surface and image-side surface being aspheric, and at least one of the object-side surface and the image-side surface having at least one inflection point; wherein, R 1 is a curvature radius of the object-side surface of the first lens element, R 2 is a curvature radius of the image-side surface of the first lens element, f is a focal length of the optical system for imaging pickup, f 1 is a focal length of the first lens element, f 5 is a focal length of the fifth lens element, and the following relations are satisfied:
| R 1 |/R 2 <−1.0;
0.5 <f 1 /f< 1.4; and
−1.5 <f 5 /f<− 0.3.
2. The optical system for imaging pickup of claim 1 , further comprising a stop, wherein S D is an axial distance between the stop and the image-side surface of the fifth lens element, T D is an axial distance between the object-side surface of the first lens element and the image-side surface of the fifth lens element, and the following relation is satisfied:
0.70 <S D /T D <1.15.
3. The optical system for imaging pickup of claim 2 , wherein the second lens element has negative refractive power.
4. The optical system for imaging pickup of claim 3 , wherein the fourth lens element has a convex image-side surface.
5. The optical system for imaging pickup of claim 4 , wherein f 2 is a focal length of the second lens element, f 3 is a focal length of the third lens element, and the following relation is satisfied:
| f 2 /f 3 |<1.5.
6. The optical system for imaging pickup of claim 5 , further comprising an image sensor, wherein ImgH is half of a diagonal length of an effective photosensitive area of the image sensor, f is the focal length of the optical system for imaging pickup, and the following relation is satisfied:
0.6<ImgH/ f< 1.0.
7. The optical system for imaging pickup of claim 5 , wherein R 2 is the curvature radius of the image-side surface of the first lens element, R 4 is a curvature radius of the image-side surface of the second lens element, and the following relation is satisfied:
−2.0 <R 2 /R 4 <−0.3.
8. The optical system for imaging pickup of claim 3 , wherein f 4 is a focal length of the fourth lens element, f is the focal length of the optical system for imaging pickup, and the following relation is satisfied:
0.3 <f 4 /f< 0.9.
9. The optical system for imaging pickup of claim 8 , wherein the first lens element has a convex object-side surface, the fourth lens element has a concave object-side surface and a convex image-side surface, and the fourth lens element and the fifth lens element are made of plastic.
10. The optical system for imaging pickup of claim 8 , wherein R 1 is the curvature radius of the object-side surface of the first lens element, R 2 is the curvature radius of the image-side surface of the first lens element, and the following relation is satisfied:
| R 1 |/R 2 <−2.0.
11. The optical system for imaging pickup of claim 8 , wherein f 2 is a focal length of the second lens element, f 3 is a focal length of the third lens element, and the following relation is satisfied:
| f 2 /f 3 |<0.5.
12. The optical system for imaging pickup of claim 8 , wherein f is the focal length of the optical system for imaging pickup, f 4 is the focal length of the fourth lens element, f 5 is the focal length of the fifth lens element, and the following relation is satisfied:
3.0 <f/f 4 |+|f/f 5 |<5.0.
13. The optical system for imaging pickup of claim 3 , further comprising an image sensor installed at an image plane for imaging an object, wherein TTL is an axial distance between the object-side surface of the first lens element and the image plane, ImgH is half of a diagonal length of an effective photosensitive area of the image sensor, and the following relation is satisfied:
TTL /ImgH<2.1.
14. An optical system for imaging pickup, sequentially arranged from an object side to an image side, comprising:
a first lens element with positive refractive power, having a convex image-side surface;
a second lens element with refractive power, having a concave image-side surface;
a third lens element with refractive power;
a fourth lens element with positive refractive power, having a convex image-side surface, both object-side surface and image-side surface being aspheric, and at least one of the object-side surface and image-side surface having at least one inflection point; and
a fifth lens element with negative refractive power, having a concave image-side surface, both object-side surface and image-side surface being aspheric, and at least one of the object-side surface and the image-side surface having at least one inflection point, wherein R 1 is a curvature radius of the object-side surface of the first lens element, R 2 is a curvature radius of the image-side surface of the first lens element, f is a focal length of the optical system for imaging pickup, f 1 is a focal length of the first lens element, f 5 is a focal length of the fifth lens element, and the following relations are satisfied:
| R 1 |/R 2 <−1.0;
0.5 <f 1 /f< 1.4; and
−1.5 <f 5 /f<− 0.3.
15. The optical system for imaging pickup of claim 14 , wherein the second lens element has negative refractive power, and the fourth lens element and the fifth lens element are made of plastic.
16. The optical system for imaging pickup of claim 15 , wherein, R 2 is the curvature radius of the image-side surface of the first lens element, R 4 is a curvature radius of the image-side surface of the second lens element, and the following relation is satisfied:
−2.0 <R 2 /R 4 <−0.3.
17. The optical system for imaging pickup of claim 15 , wherein R 1 is the curvature radius of the object-side surface of the first lens element, R 2 is the curvature radius of the image-side surface of the first lens element, and the following relation is satisfied:
| R 1 |/R 2 <−2.0.
18. The optical system for imaging pickup of claim 15 , wherein the first lens element has a convex object-side surface; f is the focal length of the optical system for imaging pickup, f 4 is a focal length of the fourth lens element, f 5 is the focal length of the fifth lens element, and the following relation is satisfied:
3.0 <|f/f 4 |+|f/f 5 |<5.0.
19. An optical system for imaging pickup, sequentially arranged from an object side to an image side, comprising:
a first lens element with positive refractive power, having a convex image-side surface;
a second lens element with negative refractive power;
a third lens element with refractive power;
a fourth lens element with positive refractive power, having both object-side surface and image-side surface being aspheric, and at least one of the object-side surface and the image-side surface having at least one inflection point; and
a fifth lens element with negative refractive power, having a concave image-side surface, both object-side surface and image-side surface being aspheric, and at least one of the object-side surface and the image-side surface having at least one inflection point, wherein R 1 is a curvature radius of the object-side surface of the first lens element, R 2 is a curvature radius of the image-side surface of the first lens element, f is a focal length of the optical system for imaging pickup, f 1 is a focal length of the first lens element, f 4 is a focal length of the fourth lens element, f 5 is a focal length of the fifth lens element, and the following relations are satisfied:
| R 1 |/R 2 <−1.0;
0.5 <f 1 /f< 1.4;
0.35 <f 4 /f< 0.67; and
−1.5 <f 5 /f<− 0.3.
20. The optical system for imaging pickup of claim 19 , further comprising a stop, wherein the fourth lens element has a concave object-side surface and a convex image-side surface; S D is an axial distance between the stop and the image-side surface of the fifth lens element, T D is an axial distance between the object-side surface of the first lens element and the image-side surface of the fifth lens element, f 2 is a focal length of the second lens element, f 3 is a focal length of the third lens element, and the following relations are satisfied:
0.7 <S D /T D <1.15; and
| f 2 /f 3 |<0.5.
21. The optical system for imaging pickup of claim 20 , wherein R 2 is the curvature radius of the image-side surface of the first lens element, R 4 is a curvature radius of the image-side surface of the second lens element, and the following relation is satisfied:
−2.0 <R 2 /R 4 <−0.3.
22. The optical system for imaging pickup of claim 19 , further comprising an image sensor, wherein ImgH is half of a diagonal length of an effective photosensitive area of the image sensor, f is the focal length of the optical system for imaging pickup, and the following relation is satisfied:
0.6<ImgH/ f< 1.0.