Optical imaging system
An optical imaging system includes a first lens group that can move in an optical direction and has negative refractive power; a second lens group that can move in the optical direction and has positive refractive power; and a third lens group that can move in the optical direction and has negative refractive power. The first lens group, the second lens group, and the third lens group include seven lenses in total, and at least one of the seven lenses includes an aspherical surface.
1. A optical imaging system, comprising:
a first lens group configured to move in an optical direction and having negative refractive power;
a second lens group configured to move in the optical direction and having positive refractive power; and
a third lens group configured to move in the optical direction and having negative refractive power,
wherein the first lens group, the second lens group, and the third lens group comprise seven lenses in total, and
wherein at least one of the seven lenses includes an aspherical surface.
2. The optical imaging system of claim 1 , wherein at least one of the seven lenses is made of a plastic material.
3. The optical imaging system of claim 1 , wherein the first lens group comprises two lenses having refractive power with different signs.
4. The optical imaging system of claim 1 ,
wherein the second lens group comprises three lenses,
wherein the three lenses of the second lens group are disposed such that the three lenses have refractive power having signs different from signs of refractive power of adjacent lenses in the second lens group.
5. The optical imaging system of claim 1 , wherein the third lens group comprises two lenses having refractive power with different signs.
6. The optical imaging system of claim 1 , further comprising:
a refractive prism disposed in front of the first lens group.
7. The optical imaging system of claim 1 , wherein, at a wide-angle end of the optical imaging system, a distance D1 between the first lens group and the second lens group is greater than a distance D3 between the third lens group and an imaging plane, and a distance D2 between the second lens group and the third lens group is greater than D3.
8. The optical imaging system of claim 7 , wherein D1/D2 is within a range of 0.9 to 1.3, D2/D3 is within a range of 1.5 to 2.2, and D1/D3 is within a range of 1.5 to 3.5.
9. The optical imaging system of claim 1 , wherein at a telephoto end of the optical imaging system, a distance D1 between the first lens group and the second lens group is smaller than a distance D2 between the second lens group and the third lens group, and D2 is smaller than a distance D3 between the third lens group and an imaging plane.
10. The optical imaging system of claim 9 , wherein D1/D2 is within a range of 0.2 to 0.4, D2/D3 is within a range of 0.2 to 0.4, and D3/D1 is within a range of 14 to 16.
11. An optical imaging system, comprising:
a prism;
a first lens having positive refractive power;
a second lens having negative refractive power;
a third lens having positive refractive power;
a fourth lens having negative refractive power;
a fifth lens having positive refractive power;
a sixth lens having positive refractive power; and
a seventh lens having negative refractive power,
wherein the prism and the first to seventh lenses are sequentially disposed from an object side.
12. The optical imaging system of claim 11 , wherein the first lens comprises a convex image-side surface.
13. The optical imaging system of claim 11 , wherein the second lens comprises a convex object-side surface.
14. The optical imaging system of claim 11 , wherein the third lens comprises a convex image-side surface.
15. The optical imaging system of claim 11 , wherein the fourth lens comprises a concave object-side surface.
16. The optical imaging system of claim 11 , wherein the sixth lens comprises a concave object-side surface.
17. The optical imaging system of claim 11 , wherein the seventh lens comprises a concave image-side surface.
18. The optical imaging system of claim 11 , wherein at least one of the lenses comprise an aspherical surface.
19. The optical imaging system of claim 11 , wherein:
−1.0<( R 1+ R 2)/( R 1− R 2)<−0.1,
where R1 is a radius of curvature of an object-side surface of the first lens, and R2 is a radius of curvature of an image-side surface of the first lens.
20. The optical imaging system of claim 11 , wherein:
0.11< Nd 6 − Nd 7<0.13,
where Nd6 is a refractive index of the sixth lens, and Nd7 is a refractive index of the seventh lens.