Optical imaging system of camera lens assembly
The present disclosure provides an optical imaging system of a camera lens assembly. The optical imaging system is sequentially provided with a first lens, a second lens, a third lens and a fourth lens from an object side to an imaging side along an optical axis. The first lens has a positive refractive power, an object side surface and an image side surface of the first lens are both convex surface. An object side surface of the second lens is a convex surface, and an image side surface of the second lens is a convex surface. The third lens has a negative refractive power and the fourth lens has a negative refractive power. An effective focal length of the first lens f1, an effective focal length of the fourth lens f4, and an effective focal length of the optical imaging system f satisfy: −0.8<(f1+f4)/f<0.
1. An optical imaging system, the optical imaging system comprising with a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged from an object side to an imaging side along an optical axis,
wherein the first lens has a positive refractive power, an object side surface of the first lens is a convex surface, and an image side surface of the first lens is a concave surface;
an object side surface of the second lens is a convex surface, and an image side surface of the second lens is a concave surface; and
the third lens and the fourth lens have negative refractive powers,
wherein an effective focal length of the first lens f1, an effective focal length of the fourth lens f4, and an effective focal length of the optical imaging system f satisfy: −0.8<(f1+f4)/f<0; and
a radius of curvature of the image side surface of the first lens R2 and a radius of curvature of the image side surface of the second lens R4 satisfy: 1<R2/R4<2.1.
2. The optical imaging system according to claim 1 , wherein the radius of curvature of the image side surface of the first lens R2 and a radius of curvature of the object side surface of the second lens R3 satisfy: 1.3<R2/R3<1.9.
3. The optical imaging system according to claim 1 , wherein an effective focal length of the third lens f3 and an effective focal length of the fourth lens f4 satisfy: 1<f3/f4<3.
4. The optical imaging system according to claim 1 , wherein an effective radius of the object side surface of the first lens DT11 and an effective radius of the object side surface of the second lens DT21 satisfy: 1.2<DT11/DT21<1.8.
5. The optical imaging system according to claim 1 , wherein an axial distance from an intersection point of an image side surface of the third lens and the optical axis to a vertex of an effective radius of the image side surface of the third lens SAG32 and a center thickness of the third lens on the optical axis CT3 satisfy: −0.7<SAG32/CT3<−0.3.
6. The optical imaging system according to claim 1 , wherein a center thickness of the first lens on the optical axis CT1 and a center thickness of the third lens on the optical axis CT3 satisfy: 2.5<CT1/CT3<3.1.
7. The optical imaging system according to claim 1 , wherein a filter is arranged between the fourth lens and an image plane, and the filter is an infrared (IR) filter.
8. The optical imaging system according to claim 7 , wherein a bandpass wavelength of the infrared (IR) filter ranges from 750 nm to 900 nm.
9. The optical imaging system according to claim 1 , wherein a distance from the object side surface of the first lens to an image plane on the optical axis TTL and the effective focal length of the optical imaging system f satisfy: TTL/f<1.
10. The optical imaging system according to claim 1 , wherein a center thickness of the first lens on the optical axis CT1 and a center thickness of the fourth lens on the optical axis CT4 satisfy: 0.4<CT4/CT1<0.8.
11. An optical imaging system, the optical imaging system comprising a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged from an object side to an imaging side along an optical axis,
wherein the first lens has a positive refractive power, an object side surface of the first lens is a convex surface, and an image side surface of the first lens is a concave surface;
an object side surface of the second lens is a convex surface, and an image side surface of the second lens is a concave surface; and
the third lens and the fourth lens have negative refractive powers,
wherein a center thickness of the first lens on the optical axis CT1 and a center thickness of the fourth lens on the optical axis CT4 satisfy: 0.4<CT4/CT1<0.8, and
a radius of curvature of the image side surface of the first lens R2 and a radius of curvature of the image side surface of the second lens R4 satisfy: 1<R2/R4<2.1.
12. The optical imaging system according to claim 11 , wherein a distance from the object side surface of the first lens to an image plane on the optical axis TTL and the center thickness of the fourth lens on the optical axis CT4 satisfy: CT4/TTL<0.1.
13. The optical imaging system according to claim 12 , wherein an effective focal length of the third lens f3 and an effective focal length of the fourth lens f4 satisfy: 1<f3/f4<3.
14. The optical imaging system according to claim 11 , wherein the radius of curvature of the image side surface of the first lens R2 and a radius of curvature of the object side surface of the second lens R3 satisfy: 1.3<R2/R3<1.9.
15. The optical imaging system according to claim 11 , wherein an effective radius of an image side surface of the fourth lens DT42 and ImgH, ImgH being half a diagonal length of an effective pixel area of an electronic photosensitive element, satisfy: 0.5<DT42/ImgH<0.9.
16. The optical imaging system according to claim 11 , wherein an axial distance from an intersection point of an image side surface of the third lens and the optical axis to a vertex of an effective radius of the image side surface of the third lens SAG32 and a center thickness of the third lens on the optical axis CT3 satisfy: −0.7<SAG32/CT3<−0.3.
17. The optical imaging system according to claim 11 , wherein an effective focal length of the third lens f3, an effective focal length of the fourth lens f4, and an effective focal length of the optical imaging system f satisfy: −4.5<(f3+f4)/f<−3.
18. The optical imaging system according to claim 11 , wherein the center thickness of the first lens on the optical axis CT1 and a center thickness of the third lens on the optical axis CT3 satisfy: 2.5<CT1/CT3<3.1.
19. The optical imaging system according to claim 11 , wherein a distance from the object side surface of the first lens to an image plane on the optical axis TTL and an effective focal length of the optical imaging system f satisfy: TTL/f<1.