Optical system, lens module, and terminal device
An optical system, a lens module, and a terminal device are provided. The optical system includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens. The first lens with a positive refractive power has an object-side surface which is convex at an optical axis. The second lens with a negative refractive power has an image-side surface which is concave at the optical axis. The third lens with a negative refractive power has an object-side surface which is convex at the optical axis and an image-side surface which is concave at the optical axis. The fourth lens with a negative refractive power has an image-side surface which is concave at the optical axis. The fifth lens and the sixth lens have the refractive power. The optical system satisfies expression 1<ftLtl4/ftGtl4<1.5.
1. An optical system comprising six lenses in total arranged in order from an object side to an image side, the six lenses comprise:
a first lens with a positive refractive power, wherein the first lens has an object-side surface which is convex at an optical axis;
a second lens with a negative refractive power, wherein the second lens has an image-side surface which is concave at the optical axis;
a third lens with a negative refractive power, wherein the third lens has an object-side surface which is convex at the optical axis and an image-side surface which is concave at the optical axis;
a fourth lens with a negative refractive power, wherein the fourth lens has an image-side surface which is concave at the optical axis;
a fifth lens with a refractive power; and
a sixth lens with a refractive power;
wherein the optical system satisfies the following expression:
1≤ftLtl4/ftGtl4<1.5,
wherein ftLtl4 represents a longest distance from the object-side surface of the fourth lens to the image-side surface of the fourth lens in a direction parallel to the optical axis, and ftGtl4 represents a shortest distance from the object-side surface of the fourth lens to the image-side surface of the fourth lens in the direction parallel to the optical axis.
2. The optical system as claimed in claim 1 , wherein the optical system satisfies the following expression:
0.5< DL 1/Imgh<1,
wherein DL1 represents an effective aperture of the first lens, and Imgh represents half of a diagonal length of an effective pixel area of the optical system on an imaging surface.
3. The optical system as claimed in claim 1 , wherein the optical system satisfies the following expression:
2< f/f 1<3,
wherein f represents an effective focal length of the optical system, and f1 represents a focal length of the first lens.
4. The optical system as claimed in claim 1 , wherein the optical system satisfies the following expression:
−0.5< f 1/ f 2<−0.2,
wherein f1 represents a focal length of the first lens, and f2 represents a focal length of the second lens.
5. The optical system as claimed in claim 1 , wherein the optical system satisfies the following expression:
0.05<airL3/ TTL< 0.3,
wherein airL3 represents a distance on the optical axis from the image-side surface of the third lens to the object-side surface of the fourth lens, and TTL represents a distance on the optical axis from the object-side surface of the first lens to an imaging surface of the optical system.
6. The optical system as claimed in claim 1 , wherein the optical system satisfies the following expression:
1 mm<( R 5* R 6)/( R 5+ R 6)<4.5 mm,
wherein R5 represents a radius of curvature of the object-side surface of the third lens on the optical axis, and R6 represents a radius of curvature of the image-side surface of the third lens on the optical axis.
7. The optical system as claimed in claim 1 , wherein the optical system satisfies the following expression:
FBL/TTL> 0.1,
wherein FBL represents a distance on the optical axis from an intersection between the image-side surface of the sixth lens and the optical axis to an imaging surface of the optical system, and TTL represents a distance on the optical axis from the object-side surface of the first lens to the imaging surface of the optical system.
8. The optical system as claimed in claim 1 , further comprising:
a stop located at an object side of the first lens or between two adjacent lenses among the plurality of lenses, and
the optical system satisfying the following expression:
0.5< DL /Imgh<1,
wherein DL represents an aperture of the stop, and Imgh represents half of a diagonal length of an effective pixel area of the optical system on an imaging surface.
9. The optical system as claimed in claim 1 , further comprising:
a stop located at the object side of the first lens or between two adjacent lenses among the plurality of lenses, and
the optical system satisfying the following expression:
1.5< TTL/DL< 2.2,
wherein TTL represents a distance on the optical axis from the object-side surface of the first lens to an imaging surface of the optical system, and DL represents an aperture of the stop.
10. The optical system as claimed in claim 1 , wherein the optical system satisfies the following expression:
0.7< TTL/f< 1,
wherein TTL represents a distance on the optical axis from the object-side surface of the first lens to an imaging surface of the optical system, and f represents an effective focal length of the optical system.
11. A lens module, comprising:
an optical system, comprising six lenses in total arranged in order from an object side to an image side, the six lenses comprise:
a first lens with a positive refractive power, wherein the first lens has an object-side surface which is convex at an optical axis;
a second lens with a negative refractive power, wherein the second lens has an image-side surface which is concave at the optical axis;
a third lens with a negative refractive power, wherein the third lens has an object-side surface which is convex at the optical axis and an image-side surface which is concave at the optical axis;
a fourth lens with a negative refractive power, wherein the fourth lens has an image-side surface which is concave at the optical axis;
a fifth lens with a refractive power; and
a sixth lens with a refractive power;
wherein the optical system satisfies the following expression:
1≤ftLtl4/ftGtl4<1.5,
wherein ftLtl4 represents a longest distance from the object-side surface of the fourth lens to the image-side surface of the fourth lens in a direction parallel to the optical axis, and ftGtl4 represents a shortest distance from the object-side surface of the fourth lens to the image-side surface of the fourth lens in the direction parallel to the optical axis; and
a photosensitive element located at the image side of the optical system.
12. The lens module as claimed in claim 11 , wherein the optical system satisfies the following expression:
0.5< DL 1/Imgh<1,
wherein DL1 represents an effective aperture of the first lens, and Imgh represents half of a diagonal length of an effective pixel area of the optical system on an imaging surface.
13. The lens module as claimed in claim 11 , wherein the optical system satisfies the following expression:
2< f/f 1<3,
wherein f represents an effective focal length of the optical system, and f1 represents a focal length of the first lens.
14. The lens module as claimed in claim 11 , wherein the optical system satisfies the following expression:
−0.5< f 1/ f 2<−0.2,
wherein f1 represents a focal length of the first lens, and f2 represents a focal length of the second lens.
15. The lens module as claimed in claim 11 , wherein the optical system satisfies the following expression:
0.05<airL3/ TTL< 0.3,
wherein airL3 represents a distance on the optical axis from the image-side surface of the third lens to the object-side surface of the fourth lens, and TTL represents a distance on the optical axis from the object-side surface of the first lens to an imaging surface of the optical system.
16. The lens module as claimed in claim 11 , wherein the optical system satisfies the following expression:
1 mm<( R 5* R 6)/( R 5+ R 6)<4.5 mm,
wherein R5 represents a radius of curvature of the object-side surface of the third lens on the optical axis, and R6 represents a radius of curvature of the image-side surface of the third lens on the optical axis.
17. The lens module as claimed in claim 11 , wherein the optical system satisfies the following expression:
FBL/TTL> 0.1,
wherein FBL represents a distance on the optical axis from an intersection between the image-side surface of the sixth lens and the optical axis to an imaging surface of the optical system, and TTL represents a distance on the optical axis from the object-side surface of the first lens to the imaging surface of the optical system.
18. The lens module as claimed in claim 11 , wherein the optical system further comprises:
a stop located at an object side of the first lens or between two adjacent lenses among the plurality of lenses, and
the optical system satisfying the following expression:
0.5< DL /Imgh<1,
wherein DL represents an aperture of the stop, and Imgh represents half of a diagonal length of an effective pixel area of the optical system on an imaging surface.
19. The lens module as claimed in claim 11 , wherein the optical system further comprises:
a stop located at the object side of the first lens or between two adjacent lenses among the plurality of lenses, and
the optical system satisfying the following expression:
1.5< TTL/DL< 2.2,
wherein TTL represents a distance on the optical axis from the object-side surface of the first lens to an imaging surface of the optical system, and DL represents an aperture of the stop.
20. A terminal device, comprising:
the lens module as claimed in claim 11 .