Optical imaging system
An optical imaging system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, an eighth lens, and a ninth lens sequentially arranged from an object side, wherein the first lens has positive refractive power, the second lens has negative refractive power and a refractive index higher than 1.6, any one of the third lens and the fourth lens has a refractive index higher than 1.6, the sixth lens has negative refractive power and a refractive index higher than 1.6, and TTL/(2*IMG HT)<0.61, where TTL is a distance on an optical axis from an object-side surface of the first lens to an imaging plane, and IMG HT is half a diagonal length of the imaging plane.
1 . An optical imaging system comprising:
a first lens, a second lens, a third lens having positive refractive power, a fourth lens having positive refractive power, a fifth lens having negative refractive power, a sixth lens, a seventh lens having positive refractive power, a convex object-side surface in a paraxial region thereof, and a concave image-side surface in a paraxial region thereof, an eighth lens, and a ninth lens sequentially arranged from an object side,
wherein the first lens has positive refractive power,
wherein the second lens has negative refractive power and a refractive index higher than 1.6,
wherein any one of the third lens and the fourth lens has a refractive index higher than 1.6,
wherein the sixth lens has negative refractive power and a refractive index higher than 1.6,
wherein TTL/(2*IMG HT)<0.61, where TTL is a distance on an optical axis from an object-side surface of the first lens to an imaging plane, and IMG HT is half a diagonal length of the imaging plane, and
wherein f1/|f2|<0.34, where f1 is a focal length of the first lens, and f2 is a focal length of the second lens.
2 . The optical imaging system of claim 1 , wherein TTL/ΣCT<2, where ΣCT is a sum of thicknesses on the optical axis of the first to ninth lenses.
3 . The optical imaging system of claim 1 , wherein 0.6<f/f1<1.5, where f is an overall focal length of the optical imaging system, and f1 is a focal length of the first lens.
4 . The optical imaging system of claim 1 , wherein v1−v2>30, where v1 is an Abbe number of the first lens, and v2 is an Abbe number of the second lens.
5 . The optical imaging system of claim 1 , wherein 1<TTL/f<1.25, where f is an overall focal length of the optical imaging system.
6 . The optical imaging system of claim 1 , wherein n2+n3>3.15, where n2 is a refractive index of the second lens, and n3 is a refractive index of the third lens.
7 . The optical imaging system of claim 1 , wherein 0.15<BFL/f<0.25, where f is an overall focal length of the optical imaging system, and BFL is a distance on the optical axis from an image-side surface of the ninth lens to the imaging plane.
8 . The optical imaging system of claim 1 , wherein 0.001<D1/f<0.04, where D1 is a distance on the optical axis between an image-side surface of the first lens and an object-side surface of the second lens, and f is an overall focal length of the optical imaging system.
9 . The optical imaging system of claim 1 , wherein 0.3<R1/f<0.4, where R1 is a radius of curvature of the object-side surface of the first lens, and f is an overall focal length of the optical imaging system.
10 . The optical imaging system of claim 1 , wherein Fno<2.3, where Fno is an f-number of the optical imaging system.
11 . The optical imaging system of claim 1 ,
wherein the eighth lens has positive refractive power and the ninth lens has negative refractive power.
12 . An optical imaging system comprising:
a first lens having positive refractive power, a convex object-side surface, and a concave image-side surface;
a second lens having negative refractive power, a convex object-side surface, and a concave image-side surface;
a third lens having positive refractive power, a convex object-side surface, and a concave image-side surface;
a fourth lens having positive refractive power, and a fifth lens having negative refractive power;
a sixth lens having negative refractive power and a refractive index higher than 1.6;
a seventh lens having positive refractive power, a convex object-side surface in a paraxial region thereof, and a concave image-side surface in a paraxial region thereof, and an eighth lens each having positive refractive power; and
a ninth lens having negative refractive power,
wherein the first to ninth lenses are sequentially arranged from an object side,
wherein TTL/ΣCT<2, where TTL is a distance on an optical axis from an object-side surface of the first lens to an imaging plane, and ΣCT is a sum of thicknesses on the optical axis of the first to ninth lenses, and
wherein f1/|f2|<0.34, where f1 is a focal length of the first lens, and f2 is a focal length of the second lens.
13 . The optical imaging system of claim 12 , wherein TTL/(2*IMG HT)<0.61, where IMG HT is half a diagonal length of the imaging plane.
14 . The optical imaging system of claim 12 , wherein the eighth lens has a convex object-side surface and a concave image-side surface, and
wherein the ninth lens has a concave object-side surface and a concave image-side surface.
15 . The optical imaging system of claim 12 , wherein the second lens, and any one of the third lens and the fourth lens each have a refractive index higher than 1.6.
16 . An optical imaging system comprising:
a first lens having positive refractive power;
a second lens having negative refractive power;
a third lens having positive refractive power, a convex object-side surface, and a concave image-side surface;
a fourth lens having positive refractive power, and a fifth lens having negative refractive power;
a sixth lens having negative refractive power and a refractive index higher than 1.6;
a seventh lens and an eighth lens each having positive refractive power, a convex object-side surface, and a concave image-side surface; and
a ninth lens having negative refractive power, a concave object-side surface, and a concave image-side surface,
wherein the first to ninth lenses are sequentially arranged from an object side,
wherein 0.6<f/f1<1.5, where f is an overall focal length of the optical imaging system, and f 1 is a focal length of the first lens, and
wherein f1/|f2|<0.34, where f2 is a focal length of the second lens.
17 . The optical imaging system of claim 16 , wherein the second lens, and any one of the third lens and the fourth lens each have a refractive index higher than 1.6.