Optical imaging system
An optical imaging system includes a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a negative refractive power, a fourth lens, a fifth lens, and a sixth lens having a positive refractive power and having a convex image-side shape, sequentially arranged in a direction from an object side of the optical imaging system to an imaging plane of the optical imaging system.
1. An optical imaging system, comprising:
a first lens comprising a convex image-side surface, a second lens, a third lens comprising negative refractive power, a fourth lens, a fifth lens, and a sixth lens comprising positive refractive power and a convex object-side surface in a paraxial portion sequentially arranged from an object side to an image side,
wherein 0.7<TL/f<1.0 and 0.1<D45/TL<0.7,
where TL represents a distance from an object-side surface of the first lens to an imaging plane, f represents a total focal length of the optical imaging system, and D45 represents a distance from an image-side surface of the fourth lens to an object-side surface of the fifth lens.
2. The optical imaging system of claim 1 , wherein the first lens comprises positive refractive power.
3. The optical imaging system of claim 1 , wherein the second lens comprises negative refractive power.
4. The optical imaging system of claim 1 , wherein the fifth lens comprises negative refractive power.
5. The optical imaging system of claim 1 , wherein the second lens comprises a convex object-side surface.
6. The optical imaging system of claim 1 , wherein the second lens comprises a concave image-side surface.
7. The optical imaging system of claim 1 , wherein the third lens comprises a concave image-side surface.
8. The optical imaging system of claim 1 , wherein the fourth lens comprises a convex object-side surface along the optical axis.
9. The optical imaging system of claim 1 , wherein the fourth lens comprises a convex image-side surface along the optical axis.
10. The optical imaging system of claim 1 , wherein the fifth lens comprises a concave image-side surface along the optical axis.
11. The optical imaging system of claim 1 , wherein the sixth lens comprises a convex image-side surface along the optical axis.
12. An optical imaging system, comprising:
a first lens, a second lens, a third lens comprising negative refractive power, a fourth lens comprising a convex object-side surface, a fifth lens, and a sixth lens comprising positive refractive power and a convex object-side surface in a paraxial portion sequentially arranged from an object side to an image side,
wherein 0.7<TL/f<1.0 and 0.1<D45/TL<0.7,
where TL represents a distance from an object-side surface of the first lens to an imaging plane, f represents a total focal length of the optical imaging system, and D45 represents a distance from an image-side surface of the fourth lens to an object-side surface of the fifth lens.
13. The optical imaging system of claim 12 , wherein:
0.15< R 1/ f< 0.32,
where R1 represents a radius of curvature of an object-side surface of the first lens.
14. The optical imaging system of claim 12 , wherein:
−3.5< f/f 2<−0.5,
where f2 represents a focal length of the second lens.
15. The optical imaging system of claim 12 , wherein:
1.60< Nd 6<1.75,
where Nd6 represents a refractive index of the sixth lens.
16. The optical imaging system of claim 12 , wherein:
0.3<tan θ<0.5
where θ represents a half angle of view of the optical imaging system.
17. The optical imaging system of claim 12 , wherein:
2.0< f/EPD< 2.7,
where EPD represents a diameter of an entrance aperture.
18. The optical imaging system of claim 12 , wherein the sixth lens comprises an inflection point formed on an image-side surface.