CN218866209U

CN218866209U - Optical system, camera module and terminal equipment

Info

Publication number: CN218866209U
Application number: CN202223090209.0U
Authority: CN
Inventors: 刘明珠; 焦俊辉
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2022-11-17
Filing date: 2022-11-17
Publication date: 2023-04-14
Anticipated expiration: 2032-11-17

Abstract

The utility model discloses an optical system, module and terminal equipment make a video recording. The optical system includes: the object side surface of the first lens element is convex at a paraxial region, and the image side surface of the first lens element is concave at a paraxial region; the object-side surface of the second lens element is concave at paraxial region, and the image-side surface thereof is convex at paraxial region; the object side surface and the image side surface of the third lens are convex at a paraxial region; the object side surface of the fourth lens element is concave at a paraxial region, and the image side surface thereof is convex at a paraxial region; the optical system satisfies the relationship: 210 °/mm < FOV/f < 300 °/mm; the optical system of the embodiment of the application has a large field angle, meets the miniaturization design and can meet the requirement of high imaging quality.

Description

Optical system, camera module and terminal equipment

Technical Field

The utility model relates to a photographic imaging technology field especially relates to an optical system, module and terminal equipment make a video recording.

Background

With the rapid development of science and technology, the medical industry has made great progress, and the technology of examination using an endoscope and minimally invasive surgery using an endoscope has gradually developed and matured. The endoscope is used as an optical instrument, can enter a human body through a natural channel of the human body to image a lesion part, and can directly observe the lesion in an organ. However, the existing endoscope detection equipment in the medical field has large volume and small field of view, thereby easily influencing medical diagnosis.

SUMMERY OF THE UTILITY MODEL

The utility model discloses aim at solving one of the technical problem that exists among the prior art at least. To this end, the present application proposes, in a first aspect, an optical system that satisfies a miniaturized design while having a large angle of view, and that can satisfy a demand for high imaging quality.

The utility model discloses the second aspect still provides a module of making a video recording.

The utility model discloses the third aspect still provides a terminal equipment.

The optical system according to the first aspect of the present application, wherein the number of the lenses with refractive power is four, and the optical system sequentially includes, from an object side to an image side along an optical axis: a first lens element with negative refractive power having a convex object-side surface and a concave image-side surface; a second lens element with negative refractive power having a concave object-side surface at a paraxial region and a convex image-side surface at a paraxial region; a third lens element with positive refractive power having a convex object-side surface and a convex image-side surface; the fourth lens element with negative refractive power has a concave object-side surface at a paraxial region and a convex image-side surface at a paraxial region.

In the optical system, the first lens element with negative refractive power has a convex-concave design with the object-side surface and the image-side surface at a paraxial region, which is favorable for enhancing the negative refractive power of the first lens element and converging large-angle incident light rays so as to increase the field angle of the optical system; the second lens element with negative refractive power can correct spherical aberration of light rays generated by the first lens element, and the second lens element with concave object-side surface and convex image-side surface can further contribute to convergence of light rays and improve optical performance of the optical system; the third lens element with positive refractive power and convex surface is favorable for smooth transition of large-angle light, further converges light, and shortens the total system length of the optical system, and is matched with the fourth lens element with negative refractive power, and the object side surface and the image side surface of the fourth lens element are respectively designed to be concave-convex surfaces at the paraxial region, so that astigmatism generated by the object side lens elements (namely the first lens element and the second lens element) of the optical system is favorably corrected, aberration which is difficult to correct and is brought by the object side lens elements (namely the first lens element and the second lens element) when converging incident light is balanced, the generation of chromatic aberration is reduced, and the imaging quality of the optical system is improved.

In one embodiment, the optical system satisfies the relationship:

FOV/f is more than 210 degrees/mm and less than 300 degrees/mm; FOV is the maximum field angle of the optical system, and fsaid is the effective focal length of the optical system. Satisfying the above relational expression makes it possible to satisfy the miniaturization demand while having a large angle of view.

In one embodiment, the optical system satisfies the relationship:

140 ° < FOV < 150 °; the FOV is the maximum field angle of the optical system. The optical system can have a large field angle by satisfying the relational expression, and the shooting requirement of a wide field angle range is met.

In one embodiment, the optical system satisfies the relationship:

0.05 < | f1/f2| < 0.12;21 < | f2/f3| < 38;0.58 < | f3/f4| < 0.65; f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, and f4 is the effective focal length of the fourth lens. Satisfying above-mentioned relational expression, can be favorable to the rational distribution Of the refractive power Of reasonable control each lens in optical system, simultaneously, effective focal length that can also effectual control optical system for effective focal length reduces rationally (for example be less than 0.6 mm), thereby makes optical system's DOF (Depth Of field) wider, and the Depth Of field effect is better.

In one embodiment, the optical system further comprises a stop located between the image-side surface of the second lens and the object-side surface of the third lens, the optical system satisfying the relationship:

CT2/CT1 is more than 1.45 and less than 2.35; CT1 is the thickness of the first lens element on the optical axis, i.e. the middle thickness of the first lens element, and CT2 is the thickness of the second lens element on the optical axis, i.e. the middle thickness of the second lens element. Satisfy above-mentioned relational expression, the well thickness that can rationally control first lens and the well thickness of second lens, the reasonable face type of lens is convenient for injection moulding, homogeneity when being favorable to the injection moulding to can be favorable to the equipment of first lens and second lens, in addition, still be favorable to shortening optical system's overall length, do benefit to the miniaturized design that realizes optical system.

In one embodiment, the optical system satisfies the relationship:

4.9 < (CT 1+ CT2+ CT3+ CT 4)/(AC 1+ AC2+ AC 3) < 5.5; CT1 is the thickness of the first lens element on the optical axis, CT2 is the thickness of the second lens element on the optical axis, CT3 is the thickness of the third lens element on the optical axis, CT4 is the thickness of the fourth lens element on the optical axis, AC1 is the air space between the first lens element and the second lens element on the optical axis, AC2 is the air space between the second lens element and the third lens element on the optical axis, and AC3 is the air space between the third lens element and the fourth lens element on the optical axis. Satisfy above-mentioned relational expression, the thickness and the clearance of each lens can rationally be distributed, can shorten optical system's overall length, do benefit to optical system miniaturized design, can also promote optical system imaging quality.

In one embodiment, the optical system satisfies the relationship:

f/TTL is less than 0.2; TTL is a distance on an optical axis from an object-side surface of the first lens element to an imaging surface of the optical system, and f is an effective focal length of the optical system. Satisfying the above relation allows the optical system to match with a large-sized (e.g., 1/14 inch) photo-sensitive chip, and also achieves a good imaging effect.

In one embodiment, the optical system satisfies the relationship:

TTL/FNO is more than 0.6mm and less than 0.7mm; TTL is a distance on an optical axis from an object-side surface of the first lens element to an imaging surface of the optical system, and FNO is an f-number of the optical system. The relation is satisfied, so that the optical system has shorter total optical length and smaller aperture, the optical system can meet the miniaturization requirement, and the depth of field requirement is met.

In one embodiment, the optical system satisfies the relationship:

0.42mm less than (TTL-BFL)/FNO less than 0.47mm; BFL is the distance on the optical axis from the image side surface of the fourth lens to the imaging surface, TTL is the distance on the optical axis from the object side surface of the first lens to the imaging surface of the optical system, and FNO is the f-number of the optical system. The optical system has shorter optical back focus, can meet the miniaturization requirement, and has a small aperture to meet the depth of field requirement.

In one embodiment, the optical system satisfies the relationship:

2.5 < Vd1/Vd2 < 2.8; vd3/Vd4 is more than 2.3 and less than 2.4; vd1 is an abbe number of the first lens, vd2 is an abbe number of the second lens, vd3 is an abbe number of the third lens, and Vd4 is an abbe number of the fourth lens. Satisfying the above relation, being favorable to correcting the aberration, can improving the imaging quality, and also being favorable to the central imaging to approach the diffraction limit.

In one embodiment, the optical system satisfies the relationship:

1.5 < | R42/R31| < 2; r31 is the curvature radius of the object side surface of the third lens at the optical axis, R42 is the curvature radius of the image side surface of the fourth lens at the optical axis, and the diaphragm is positioned between the image side surface of the second lens and the object side surface of the third lens. R31 and R42 are both positioned on one side of the diaphragm facing the imaging surface, so that the sensitivity of the optical system is higher, the relational expression is satisfied, the sensitivity of the optical system can be effectively reduced, and the assembly yield is improved.

In one embodiment, the optical system satisfies the relationship:

FOV/FNO is more than 31 degrees and less than 33 degrees; FOV is the maximum field angle of the optical system and FNO is the f-number of the optical system. The optical system can meet the requirements of large-angle shooting and depth of field at the same time by meeting the relational expression.

In one embodiment, the optical system satisfies the relationship:

f/FNO is more than 0.1mm and less than 0.15mm; FNO is an f-number of the optical system, and f is an effective focal length of the optical system. The optical system has smaller focal length and reasonable aperture, and can be beneficial to balancing the imaging quality and the depth of field range of the optical system, namely, the requirements of imaging and depth of field are met.

In one embodiment, the optical system satisfies the relationship:

1.5mm < | f1+ f2+ f3+ f4|/FNO < 3mm; f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, f4 is the effective focal length of the fourth lens, and FNO is the f-number of the optical system. Satisfying the above relation, the effective focal length Of the optical system can be effectively controlled, so that the effective focal length Of the optical system is reasonably reduced (for example, less than 0.6 mm), and the DOF (Depth Of Focus) Of the optical system is wider and the Depth Of field effect is better.

In one embodiment, the optical system satisfies the relationship:

2.8 < (CT 1+ CT2+ CT3+ CT 4)/f < 3.1; CT1 is the thickness of the first lens element on the optical axis, CT2 is the thickness of the second lens element on the optical axis, CT3 is the thickness of the third lens element on the optical axis, CT4 is the thickness of the fourth lens element on the optical axis, and f is the effective focal length of the optical system. The optical system satisfies the relation, the thickness of each lens can be reasonably controlled under a smaller focal length, the total length of the optical system is favorably shortened, and the miniaturization design of the optical system is favorably realized.

In one embodiment, the optical system satisfies the relationship:

0.35mm < (CT 1+ CT2+ CT3+ CT 4)/FNO < 0.39mm; CT1 is the thickness of the first lens on the optical axis; CT2 is the thickness of the second lens element on the optical axis, and CT3 is the thickness of the third lens element on the optical axis; CT4 is the thickness of the fourth lens on the optical axis, and FNO is the f-number of the optical system. The relation is satisfied, so that the optical system has smaller lens thickness and appropriate aperture, the total length of the optical system can be shortened, the miniaturization design of the optical system is facilitated, and the requirement of depth of field is satisfied.

In one embodiment, the optical system satisfies the relationship:

1.7 < (CT 1+ CT2+ CT3+ CT 4)/BFL < 1.9; CT1 is the thickness of the first lens element on the optical axis, CT2 is the thickness of the second lens element on the optical axis, CT3 is the thickness of the third lens element on the optical axis, CT4 is the thickness of the fourth lens element on the optical axis, and BFL is the distance from the image side surface of the fourth lens element to the imaging surface on the optical axis. Satisfying above-mentioned relational expression, can shortening optical system's overall length, be favorable to optical system miniaturized design, still be favorable to reducing the manufacturing degree of difficulty of each lens simultaneously.

In one embodiment, the optical system satisfies the relationship:

13.7mm ^-1 ＜FNO/(AC1+AC2+AC3)＜14.2mm ^-1 (ii) a AC1 is an air space on the optical axis between the first lens and the second lens, AC2 is an air space on the optical axis between the second lens and the third lens, AC3 is an air space on the optical axis between the third lens and the fourth lens, and FNO is an f-number of the optical system. Satisfying the above relation, the clear aperture of the optical system can be effectively controlled, and the reasonable space between the lenses enables the light of the small aperture to have sufficient space transition, which can improve the imaging quality and is beneficial to the optimization of RI (Relative illumination).

In one embodiment, the optical system satisfies the relationship:

f/(AC 1+ AC2+ AC 3) < 1.6 < 1.9; AC1 is an air space between the first lens element and the second lens element on the optical axis, AC2 is an air space between the second lens element and the third lens element on the optical axis, AC3 is an air space between the third lens element and the fourth lens element on the optical axis, and f is an effective focal length of the optical system. Satisfy above-mentioned relational expression, be favorable to reasonable control optical system's overall length, realize optical system's miniaturized design to effectively balance optical system's overall length and effective focal length, and then promote optical system's imaging quality.

In one embodiment, the optical system satisfies the relationship:

0.33 < (AC 1+ AC2+ AC 3)/BFL < 0.35; AC1 is an air space between the first lens element and the second lens element on the optical axis, AC2 is an air space between the second lens element and the third lens element on the optical axis, AC3 is an air space between the third lens element and the fourth lens element on the optical axis, and BFL is a distance from an image side surface of the fourth lens element to an image plane on the optical axis. The imaging quality of the optical system can be improved, and the manufacturing difficulty of each lens can be reduced.

The camera module according to the second aspect of the present application includes a photosensitive chip and the optical system described above, where the photosensitive chip is disposed on the image side of the optical system. Through adopting above-mentioned optical system, satisfy the miniaturized design when the module of making a video recording can have great angle of field, can satisfy high imaging quality's demand simultaneously.

According to the third aspect of the application, the terminal device comprises a fixing piece and the camera module, and the camera module is arranged on the fixing piece. The camera module can meet the requirements of miniaturization design and high imaging quality when having a large field angle.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

Fig. 1 is a schematic structural diagram of an optical system according to a first embodiment of the present application;

FIG. 2 includes a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of the optical system in the first embodiment;

fig. 3 is a schematic structural diagram of an optical system according to a second embodiment of the present application;

FIG. 4 includes a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of the optical system in the second embodiment;

fig. 5 is a schematic structural diagram of an optical system according to a third embodiment of the present application;

FIG. 6 includes a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of the optical system in the third embodiment;

fig. 7 is a schematic structural diagram of an optical system according to a fourth embodiment of the present application;

FIG. 8 includes a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of the optical system in the fourth embodiment;

fig. 9 is a schematic structural diagram of an optical system according to a fifth embodiment of the present application;

FIG. 10 includes a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of the optical system in the fifth embodiment;

fig. 11 is a schematic view of a camera module according to an embodiment of the present application;

fig. 12 is a schematic structural diagram of a terminal device according to an embodiment of the present application.

Reference numerals:

the optical system 10, the camera module 20,

the optical axis 101, the photosensitive chip 210, the stop STO,

first lens L1: the object side S1, the image side S2,

second lens L2: the object side S3, like the side S4,

third lens L3: the object side S5, the image side S6,

fourth lens L4: the object side S7, the image side S8,

a filter object side surface S9, a filter image side surface S10,

the optical filter 110, the image plane S11, the terminal device 30,

a fixing member 310.

Detailed Description

Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary intended for explaining the present invention, and should not be construed as limiting the present invention.

An optical system 10 according to an embodiment of the present invention will be described below with reference to the drawings.

Referring to fig. 1, an optical system 10 with a four-lens design is provided in the present application, and the optical system 10 includes, in order along an optical axis 101, a first lens element L1 with negative refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, and a fourth lens element L4 with negative refractive power. The lenses in the optical system 10 should be coaxially arranged, the common axis of the lenses is the optical axis 101 of the optical system 10, and the lenses can be installed in a lens barrel to form an image pickup lens.

The first lens L1 has an object-side surface S1 and an image-side surface S2, the second lens L2 has an object-side surface S3 and an image-side surface S4, the third lens L3 has an object-side surface S5 and an image-side surface S6, and the fourth lens L4 has an object-side surface S7 and an image-side surface S8. Meanwhile, the optical system 10 further has an imaging surface S11, the imaging surface S11 is located on the image side of the fourth lens element L4, and light rays emitted from an on-axis object point at a corresponding object distance can be converged on the imaging surface S11 after being adjusted by each lens element of the optical system 10.

Generally, the imaging surface S11 of the optical system 10 coincides with the photosensitive surface of the photosensitive chip 210. It should be noted that, in some embodiments, the optical system 10 may match an image sensor having a rectangular photosensitive surface, and the imaging surface S11 of the optical system 10 coincides with the rectangular photosensitive surface of the image sensor. At this time, the effective pixel area on the imaging surface S11 of the optical system 10 has a horizontal direction, a vertical direction, and a diagonal direction, and in this application, the maximum angle of view of the optical system 10 is understood to be the maximum angle of view of the optical system 10 in the diagonal direction, and the image height corresponding to the maximum angle of view is understood to be half the length of the effective pixel area on the imaging surface S11 of the optical system 10 in the diagonal direction.

In the embodiment of the present application, the object-side surface S1 of the first lens element L1 is convex at the paraxial region 101, and the image-side surface S2 is concave at the paraxial region 101; the object-side surface S3 of the second lens element L2 is concave at the paraxial region 101, and the image-side surface S4 is convex at the paraxial region 101; the object-side surface S5 of the third lens element L3 is convex at the paraxial region, and the image-side surface S6 is convex at the paraxial region 101; the object-side surface S7 of the fourth lens element L4 is concave at the paraxial region 101, and the image-side surface S8 is convex at the paraxial region 101. When it is described that a lens surface has a certain profile at a paraxial region 101, that is, the lens surface has the certain profile in the vicinity of the optical axis 101; when describing a lens surface as having a profile near the maximum effective aperture, the lens surface has the profile radially and near the maximum effective clear aperture.

In the optical system 10, the first lens element with negative refractive power has a convex-concave design at the paraxial region 101 with the object-side surface S1 and the image-side surface S2, which is favorable for enhancing the negative refractive power of the first lens element L1 and converging large-angle incident light beams, so as to increase the field angle of the optical system 10; by making the second lens element L2 have negative refractive power, the spherical aberration generated by the light passing through the object lens element, i.e., the first lens element L1, can be corrected, and in addition, by adopting the design that the object side surface S3 of the second lens element L2 is concave and the image side surface S4 is convex, the convergence of the light can be further facilitated, and the optical performance of the optical system 10 can be improved; the third lens element L3 with positive refractive power and convex surface facilitates smooth transition of large-angle light beams, further converges light beams, and shortens the total system length of the optical system 10, and is combined with the fourth lens element L4 with negative refractive power, and the object-side surface S7 and the image-side surface S8 of the fourth lens element are designed to be concave-convex surfaces at the paraxial region 101, so as to facilitate correction of astigmatism generated by the object-side lens element, i.e., the first lens element L1 and the second lens element L2, of the optical system 10, and simultaneously balance the difficult-to-correct aberration generated by the object-side lens element, i.e., the first lens element L1 and the second lens element L2, when converging incident light beams, reduce the generation of chromatic aberration, and improve the imaging quality of the optical system 10

In one embodiment, the optical system 10 satisfies the relationship:

210 °/mm < FOV/f < 300 °/mm; FOV is the maximum field angle of the optical system, and fsaid is the effective focal length of the optical system.

Satisfying the above relational expression makes it possible to satisfy the miniaturization requirement while providing the optical system 10 with a large angle of view.

In one embodiment, the optical system 10 satisfies the relationship:

140 ° < FOV < 150 °; the FOV is the maximum field angle of the optical system 10.

By satisfying the above relational expression, the optical system 10 can have a large angle of view, and satisfy the shooting requirement in a wide angle of view.

In one embodiment, the optical system 10 satisfies the relationship:

0.05 < | f1/f2| < 0.12;21 < | f2/f3| < 38;0.58 < | f3/f4| < 0.65; f1 is the effective focal length of the first lens element L1, f2 is the effective focal length of the second lens element L2, f3 is the effective focal length of the third lens element L3, and f4 is the effective focal length of the fourth lens element L4.

Satisfying the above relation, it is beneficial to reasonably control the refractive power Of each lens in the optical system 10, and at the same time, it is also able to effectively control the effective focal length Of the optical system 10, so that the effective focal length is reasonably reduced (for example, less than 0.6 mm), and thus the DOF (Depth Of Focus) Of the optical system 10 is wider and the Depth Of field effect is better.

In one embodiment, the optical system 10 further includes a stop ST0, the stop ST0 is located between the image-side surface S4 of the second lens L2 and the object-side surface S5 of the third lens L3, and the optical system 10 satisfies the relationship:

CT2/CT1 is more than 1.45 and less than 2.35; CT1 is the thickness of the first lens L1 on the optical axis 101, i.e. the middle thickness of the first lens L1, and CT2 is the thickness of the second lens L2 on the optical axis 101, i.e. the middle thickness of the second lens L2.

Satisfy above-mentioned relational expression, can rationally control the medium-thickness of first lens L1 and the medium-thickness of second lens L2, the reasonable face type of lens is convenient for injection moulding, and homogeneity when being favorable to the injection moulding to can be favorable to the equipment of first lens L1 and second lens L2, in addition, still be favorable to shortening optical system 10's overall length, do benefit to the miniaturized design that realizes optical system 10.

In one embodiment, the optical system 10 satisfies the relationship:

4.9 < (CT 1+ CT2+ CT3+ CT 4)/(AC 1+ AC2+ AC 3) < 5.5; CT1 is the thickness of the first lens L1 on the optical axis 101; CT2 is the thickness of the second lens L2 on the optical axis 101, and CT3 is the thickness of the third lens L3 on the optical axis 101; CT4 is the thickness of the fourth lens L4 on the optical axis 101, AC1 is the air space between the first lens L1 and the second lens L2 on the optical axis 101, AC2 is the air space between the second lens L2 and the third lens L3 on the optical axis 101, and AC3 is the air space between the third lens L3 and the fourth lens L4 on the optical axis 101.

Satisfying above-mentioned relational expression, the thickness and the clearance of each lens can rationally be distributed, can shorten optical system 10's overall length, do benefit to optical system 10 miniaturized design, can also promote optical system 10 imaging quality.

In one embodiment, the optical system 10 satisfies the relationship:

f/TTL is less than 0.2; TTL is a distance from the object-side surface S1 of the first lens element L1 to the image plane S11 of the optical system 10 on the optical axis 101, and f is an effective focal length of the optical system 10.

Satisfying the above relationship allows the optical system 10 to be matched with a large-sized (e.g., 1/14 inch) photo sensor chip 210, and also achieves a good image forming effect.

In one embodiment, the optical system 10 satisfies the relationship:

TTL/FNO is more than 0.6mm and less than 0.7mm; TTL is a distance from the object-side surface S1 of the first lens element L1 to the image plane S11 of the optical system 10 on the optical axis 101, and FNO is an f-number of the optical system 10.

Satisfying the above relation, the optical system 10 has a shorter total optical length and a smaller aperture, so that the optical system 10 can satisfy the miniaturization requirement and the depth of field requirement.

In one embodiment, the optical system 10 satisfies the relationship:

0.42mm less than (TTL-BFL)/FNO less than 0.47mm; BFL is a distance from the image-side surface S7 of the fourth lens element L4 to the image-forming surface S11 on the optical axis 101, i.e. a back focus of the optical system 10, TTL is a distance from the object-side surface S1 of the first lens element L1 to the image-forming surface S11 of the optical system 10 on the optical axis 101, and FNO is an f-number of the optical system 10.

Satisfying the above relationship, the optical system 10 has a shorter optical back focus, so that the optical system 10 can satisfy the miniaturization requirement, and the optical system 10 has a small aperture and satisfies the depth of field requirement.

In one embodiment, the optical system 10 satisfies the relationship:

2.5 < Vd1/Vd2 < 2.8;2.3 < Vd3/Vd4 < 2.4; vd1 is the abbe number of the first lens L1, vd2 is the abbe number of the second lens L2, vd3 is the abbe number of the third lens L3, and Vd4 is the abbe number of the fourth lens L4.

Satisfying the above relation, being favorable to correcting the aberration, can improving the imaging quality, and also being favorable to the central imaging to approach the diffraction limit.

In one embodiment, the optical system 10 satisfies the relationship:

1.5 < | R42/R31| < 2; r31 is a curvature radius of the object-side surface S5 of the third lens L3 at the optical axis 101, R42 is a curvature radius of the image-side surface S8 of the fourth lens L4 at the optical axis 101, and the stop ST0 is located between the image-side surface S4 of the second lens L2 and the object-side surface S5 of the third lens L3.

R31 and R42 are both on the side of the diaphragm ST0 toward the imaging surface S11, so the sensitivity of the optical system 10 is high,

satisfying the above relation, the sensitivity of the optical system 10 can be effectively reduced, and the assembly yield can be improved.

In one embodiment, the optical system 10 satisfies the relationship:

31 DEG < FOV/FNO < 33 DEG; FOV is the maximum field angle of the optical system 10 and FNO is the f-number of the optical system 10.

Satisfying the above relation, the optical system 10 can satisfy the requirements of wide-angle shooting and depth of field.

In one embodiment, the optical system 10 satisfies the relationship:

f/FNO is more than 0.1mm and less than 0.15mm; FNO is the f-number of the optical system 10, and f is the effective focal length of the optical system 10.

Satisfying the above conditional expression, the optical system 10 has a smaller focal length and a reasonable aperture, which is beneficial to balance the imaging quality and the depth of field range of the optical system 10, that is, satisfying the imaging requirement and the depth of field requirement.

Satisfying the above relation, the manufacturing difficulty of each lens can be reduced while improving the imaging quality of the optical system 10.

1.5mm < | f1+ f2+ f3+ f4|/FNO < 3mm; f1 is the effective focal length of the first lens L1, f2 is the effective focal length of the second lens L2, f3 is the effective focal length of the third lens L3, f4 is the effective focal length of the fourth lens L4, and FNO is the f-number of the optical system 10.

Satisfying the above relation, the effective focal length Of the optical system 10 can be effectively controlled, so that the effective focal length Of the optical system 10 is reasonably reduced (for example, less than 0.6 mm), and thus the DOF (Depth Of field) Of the optical system 10 is wider and the Depth Of field effect is better.

In one embodiment, the optical system 10 satisfies the relationship:

2.8 < (CT 1+ CT2+ CT3+ CT 4)/f < 3.1; CT1 is the thickness of the first lens L1 on the optical axis 101; CT2 is the thickness of the second lens L2 on the optical axis 101, and CT3 is the thickness of the third lens L3 on the optical axis 101; CT4 is the thickness of the fourth lens element L4 on the optical axis 101, and f is the effective focal length of the optical system 10.

Satisfying the above relation, the thickness of each lens of the optical system 10 can be reasonably controlled at a smaller focal length, which is beneficial to shortening the total length of the optical system 10 and to miniaturizing the optical system 10.

0.35mm < (CT 1+ CT2+ CT3+ CT 4)/FNO < 0.39mm; CT1 is the thickness of the first lens L1 on the optical axis 101; CT2 is the thickness of the second lens L2 on the optical axis 101, and CT3 is the thickness of the third lens L3 on the optical axis 101; CT4 is the thickness of the fourth lens L4 on the optical axis 101, and FNO is the f-number of the optical system 10.

Satisfying the above relation, the optical system 10 has a smaller lens thickness and a suitable aperture, which can shorten the total length of the optical system 10, facilitate the miniaturization design of the optical system 10, and satisfy the depth of field requirement.

In one embodiment, the optical system 10 satisfies the relationship:

1.7 < (CT 1+ CT2+ CT3+ CT 4)/BFL < 1.9; CT1 is a thickness of the first lens element L1 on the optical axis 101, CT2 is a thickness of the second lens element L2 on the optical axis 101, CT3 is a thickness of the third lens element L3 on the optical axis 101, CT4 is a thickness of the fourth lens element L4 on the optical axis 101, and BFL is a distance between the image-side surface S7 of the fourth lens element L4 and the image-forming surface S11 on the optical axis 101, i.e., a back focus of the optical system 10.

Satisfying the above relation, the total length of the optical system 10 can be shortened, which is beneficial to the miniaturization design of the optical system 10 and the reduction of the manufacturing difficulty of each lens.

FNO/(AC 1+ AC2+ AC 3) < 14.2mm-1, which is more than 13.7 mm-1; AC1 is an air space between the first lens L1 and the second lens L2 on the optical axis 101, AC2 is an air space between the second lens L2 and the third lens L3 on the optical axis 101, AC3 is an air space between the third lens L3 and the fourth lens L4 on the optical axis 101, and FNO is an f-number of the optical system 10.

Satisfying the above relation, the clear aperture of the optical system 10 can be effectively controlled, and the reasonable space between the lenses enables the light of the small aperture to have sufficient spatial transition, which can improve the imaging quality and is beneficial to the optimization of RI (Relative illumination).

f/(AC 1+ AC2+ AC 3) < 1.6 < 1.9; AC1 is an air space between the first lens L1 and the second lens L2 on the optical axis 101, AC2 is an air space between the second lens L2 and the third lens L3 on the optical axis 101, AC3 is an air space between the third lens L3 and the fourth lens L4 on the optical axis 101, and f is an effective focal length of the optical system 10.

Satisfying the above relation, it is beneficial to reasonably control the total length of the optical system 10, realize the miniaturization design of the optical system 10, and effectively balance the total length and the effective focal length of the optical system 10, thereby improving the imaging quality of the optical system 10.

0.33 < (AC 1+ AC2+ AC 3)/BFL < 0.35; AC1 is an air space between the first lens L1 and the second lens L2 on the optical axis 101, AC2 is an air space between the second lens L2 and the third lens L3 on the optical axis 101, AC3 is an air space between the third lens L3 and the fourth lens L4 on the optical axis 101, and BFL is a distance between the object-side surface S7 of the fourth lens L4 and the image plane S11 on the optical axis 101, i.e., a back focus of the optical system 10.

The effective focal length in the above relationships is at least the value at the paraxial region 101 with reference to the wavelength of 555nm, and the refractive power of the lens is at least the value at the paraxial region 101. And the above relationship conditions and the technical effects thereof are directed to the optical system 10 having the above lens design. When the lens design (the number of lenses, the refractive power arrangement, the surface type arrangement, etc.) of the optical system 10 cannot be ensured, it is difficult to ensure that the optical system 10 can still have the corresponding technical effect when the relational expressions are satisfied, and even the imaging performance may be significantly degraded.

In some embodiments, at least one lens in the optical system 10 may have a spherical surface shape, and the design of the spherical surface shape may reduce the difficulty and cost of manufacturing the lens. In some embodiments, at least one lens of the optical system 10 may also have an aspheric surface, which may be referred to as having an aspheric surface when at least one side surface (object side surface or image side surface) of the lens is aspheric. In one embodiment, both the object-side surface and the image-side surface of each lens can be designed to be aspheric. The aspheric design can help the optical system 10 to eliminate the aberration more effectively, improving the imaging quality. In some embodiments, the design of each lens surface in the optical system 10 may be configured by spherical and aspherical surface types in order to take into account the manufacturing cost, the manufacturing difficulty, the imaging quality, the assembling difficulty, and the like.

The surface shape of the aspheric surface can be calculated by referring to an aspheric surface formula:

wherein Z is a distance from a corresponding point on the aspheric surface to a tangent plane of the aspheric surface at the optical axis 101, r is a distance from the corresponding point on the aspheric surface to the optical axis 101, c is a curvature of the aspheric surface at the optical axis 101, k is a conic coefficient, and Ai is a high-order term coefficient corresponding to the ith-order high-order term in the aspheric surface type formula.

It should also be noted that when a lens surface is aspheric, there may be points of inflection where the surface will change in shape in the radial direction, such as where one lens surface is convex near the optical axis 101 and concave near the maximum effective aperture. The planar design of the reverse curvature point can realize good correction on field curvature and distortion aberration of the edge field in the optical system 10, and improve imaging quality.

In some embodiments, at least one lens of the optical system 10 is made of Glass (GL). For example, the first lens L1 closest to the object side may be made of glass, and the effect of the glass material of the first lens L1 on eliminating temperature drift may be utilized to effectively reduce the influence of the ambient temperature change on the optical system 10, thereby maintaining a better and more stable imaging quality. In some embodiments, the material of at least one lens in the optical system 10 may also be Plastic (PC), and the Plastic material may be polycarbonate, gum, etc. The lens made of plastic can reduce the production cost of the optical system 10, and the lens made of glass can endure higher or lower temperature and has excellent optical effect and better stability. In some embodiments, lenses of different materials may be disposed in the optical system 10, that is, a design combining a glass lens and a plastic lens may be adopted, but the specific configuration relationship may be determined according to practical requirements and is not exhaustive here.

It should be noted that the first lens L1 does not mean that there is only one lens, and in some embodiments, there may be two or more lenses in the first lens L1, and the two or more lenses can form a cemented lens, and a surface of the cemented lens closest to the object side can be regarded as the object side surface S1, and a surface of the cemented lens closest to the image side can be regarded as the image side surface S2. Alternatively, although no cemented lens is formed between the lenses of the first lens L1, the distance between the lenses is relatively fixed, and in this case, the object-side surface of the lens closest to the object side is the object-side surface S1, and the image-side surface of the lens closest to the image side is the image-side surface S2. In addition, the number of lenses in the second lens L2, the third lens L3, or the fourth lens L4 in some embodiments may also be greater than or equal to two, and a cemented lens may be formed between any two adjacent lenses, or may also be a non-cemented lens.

In some embodiments, the stop ST0 may be an aperture stop or a field stop, and the aperture stop is used to control the light incident amount and the depth of field of the optical system 10 and also achieve good interception of the ineffective light to improve the imaging quality of the optical system 10, and may be disposed between the object side of the optical system 10 and the object side surface S1 of the first lens L1. It is understood that, in other embodiments, the stop STO may also be disposed between two adjacent lenses, for example, between the second lens L2 and the third lens L3, or between the third lens L3 and the fourth lens L4, and the arrangement is adjusted according to practical situations, which is not specifically limited in the embodiment of the present application. The aperture stop STO may also be formed by a holder that holds a lens.

The optical system 10 of the present application is illustrated by the following more specific examples:

first embodiment

Referring to fig. 1, in the first embodiment, the optical system 10 includes, in order from an object side to an image side along an optical axis 101, a first lens element L1 with negative refractive power, a second lens element L2 with negative refractive power, a stop STO, a third lens element L3 with positive refractive power, and a fourth lens element L4 with negative refractive power. The respective lens surface types of the optical system 10 are as follows:

the object-side surface S1 of the first lens element L1 is convex at the paraxial region 101, and the image-side surface S2 is concave at the paraxial region 101;

the object-side surface S3 of the second lens element L2 is concave at the paraxial region 101, and the image-side surface S4 is convex at the paraxial region 101;

the object-side surface S5 of the third lens element L3 is convex at the paraxial region 101, and the image-side surface S6 is convex at the paraxial region 101;

the object-side surface S7 of the fourth lens element L4 is concave at the paraxial region 101, and the image-side surface S8 is convex at the paraxial region 101.

The object side surface S1 of the first lens L1 is convex at the circumference, and the image side surface S2 is concave at the circumference;

the object side surface S3 of the second lens L2 is concave at the circumference, and the image side surface S4 is convex at the circumference;

the object-side surface S5 of the third lens element L3 is convex at the circumference, and the image-side surface S6 is convex at the circumference;

the object-side surface S7 of the fourth lens element L4 is concave at the circumference, and the image-side surface S8 is convex at the circumference.

Further, in the present embodiment, the stop STO is an aperture stop and is located between the image-side surface S4 of the second lens L2 and the object-side surface S5 of the third lens L3.

In the first embodiment, the surfaces of the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 of the first lens L1 to the fourth lens L4 are all aspheric, and the material of each of the first lens L1 to the fourth lens L4 is Plastic (PC).

The optical system 10 further includes a filter 110, the filter 110 can be a part of the optical system 10 or can be removed from the optical system 10, but when the filter 110 is removed, the total optical length TTL of the optical system 10 remains unchanged; in this embodiment, the optical filter 110 is an infrared cut-off filter, and the infrared cut-off filter is disposed between the image side surface S8 of the fourth lens L4 and the imaging surface S11 of the optical system 10, so as to filter out light rays in invisible bands such as infrared light, and only allow visible light to pass through, so as to obtain a better image effect; it is understood that the filter 110 can also filter out light in other bands, such as visible light, and only let infrared light pass through, and the optical system 10 can be used as an infrared optical lens, that is, the optical system 10 can also image and obtain better image effect in a dark environment and other special application scenes.

The lens parameters of the optical system 10 in the first embodiment are shown in table 1 below. The elements from the object side to the image side of the optical system 10 are arranged in the order from top to bottom in table 1, wherein the stop represents the aperture stop STO. The Y radius in table 1 is the radius of curvature of the corresponding surface of the lens at the optical axis 101. In table 1, the surface with the surface number S1 represents the object-side surface of the first lens L1, the surface with the surface number S2 represents the image-side surface of the first lens L1, and so on. The absolute value of the first value of the lens in the "thickness" parameter list is the thickness of the lens on the optical axis 101, and the absolute value of the second value is the distance from the image-side surface of the lens to the next optical surface (the object-side surface or stop surface of the next lens) on the optical axis 101, wherein the stop thickness parameter represents the distance from the stop surface to the object-side surface of the adjacent lens on the image side on the optical axis 101. In the table, the reference wavelength of the refractive index and the abbe number of each lens is 587.6nm, the reference wavelength of the focal length (effective focal length) is 555nm, and the numerical units of the Y radius, the thickness and the focal length (effective focal length) are millimeters (mm). In addition, the parameter data and the lens surface shape structure used for the relational expression calculation in the following embodiments are based on the data in the lens parameter table in the corresponding embodiment.

TABLE 1

As can be seen from table 1, the effective focal length f of the optical system 10 in the first embodiment is 0.555mm, the f-number FNO is 4.5, the maximum field angle FOV of the optical system 10 is 142 °, the total optical length TTL is 2.900mm, and the total optical length TTL values in the following embodiments are the sum of the thickness values corresponding to the surface numbers S1 to S11.

Table 2 below presents the aspherical coefficients of the corresponding lens surfaces in table 1, where K is a conic coefficient and Ai is a coefficient corresponding to the i-th order higher-order term in the aspherical surface type formula.

TABLE 2

Fig. 2 includes a longitudinal spherical aberration diagram, an astigmatism diagram, and a distortion diagram of the optical system 10 in the first embodiment. Wherein the reference wavelength of the astigmatism diagram and the distortion diagram is 555nm. Longitudinal Spherical Aberration diagrams (Longitudinal Spherical Aberration) show the deviation of the converging focus of light rays of different wavelengths through the lens. The ordinate of the longitudinal spherical aberration diagram represents Normalized Pupil coordinates (Normalized Pupil coordmator) from the Pupil center to the Pupil edge, and the abscissa represents the distance (in mm) from the imaging plane S11 to the intersection of the ray and the optical axis 101. It can be known from the longitudinal spherical aberration diagram that the convergent focus deviation degrees of the light rays with the respective wavelengths in the first embodiment tend to be consistent, the maximum focus deviation of the respective reference wavelengths is controlled within ± 0.25mm, and for the optical system 10, the diffuse spots or color halos in the imaging picture are effectively suppressed. FIG. 2 also includes an astigmatism plot (volumetric Field Curves) of Field curvature of optical system 10, where the S curve represents sagittal Field curvature at 555nm and the T curve represents meridional Field curvature at 555nm. As can be seen from the figure, the field curvature of the optical system 10 is small, the maximum field curvature is controlled within ± 0.05mm, the degree of curvature of image plane is effectively suppressed for the optical system 10, the sagittal field curvature and the meridional field curvature under each field tend to be consistent, and the astigmatism of each field is better controlled, so that it is known that the center to the edge of the field of view of the optical system 10 has clear imaging. As can be seen from the distortion map, the degree of distortion of the optical system 10 having a characteristic of a large angle of view is also well controlled.

Second embodiment

Referring to fig. 3, in the second embodiment, the optical system 10 includes, in order from the object side to the image side along the optical axis 101, a first lens element L1 with negative refractive power, a second lens element L2 with negative refractive power, an aperture stop STO, a third lens element L3 with positive refractive power, and a fourth lens element L4 with negative refractive power. The respective lens surface types of the optical system 10 are as follows:

In the second embodiment, the surfaces of the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 of the first lens L1 to the fourth lens L4 are all aspheric, and the material of each of the first lens L1 to the fourth lens L4 is Plastic (PC).

The lens parameters of the optical system 10 are given in table 3, wherein the definitions of the names and parameters of the elements can be obtained from the first embodiment, which is not repeated herein.

TABLE 3

Table 4 below shows aspheric coefficients of the corresponding lens surfaces in table 3, where K is a conic coefficient and Ai is a coefficient corresponding to the i-th order high-order term in the aspheric surface type formula.

TABLE 4

As can be seen from the aberration diagrams in fig. 4, the longitudinal spherical aberration, curvature of field, astigmatism, and distortion of the optical system 10 having the wide-angle characteristic are all controlled well, and the optical system 10 of this embodiment can have good imaging quality.

Third embodiment

Referring to fig. 5, in the third embodiment, the optical system 10 includes, in order from the object side to the image side along the optical axis 101, a first lens element L1 with negative refractive power, a second lens element L2 with negative refractive power, a stop STO, a third lens element L3 with positive refractive power, and a fourth lens element L4 with negative refractive power. The respective lens surface types of the optical system 10 are as follows:

In the third embodiment, the surfaces of the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 of the first lens L1 to the fourth lens L4 are all aspheric, and the material of each of the first lens L1 to the fourth lens L4 is Plastic (PC).

The lens parameters of the optical system 10 in this embodiment are given in table 5, wherein the names and parameters of the elements can be defined in the first embodiment, which is not described herein.

TABLE 5

Table 6 below presents the aspherical coefficients of the corresponding lens surfaces in table 5, where K is a conic coefficient and Ai is a coefficient corresponding to the i-th order higher-order term in the aspherical surface type formula.

TABLE 6

As can be seen from the aberration diagrams in fig. 6, the longitudinal spherical aberration, curvature of field, astigmatism, and distortion of the optical system 10 having the wide-angle characteristic are all controlled well, and the optical system 10 of this embodiment can have good imaging quality.

Fourth embodiment

Referring to fig. 7, in the fourth embodiment, the optical system 10 includes, in order from the object side to the image side along the optical axis 101, a first lens element L1 with negative refractive power, a second lens element L2 with negative refractive power, a stop STO, a third lens element L3 with positive refractive power, and a fourth lens element L4 with negative refractive power. The respective lens surface types of the optical system 10 are as follows:

In the fourth embodiment, the surfaces of the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 of the first lens L1 to the fourth lens L4 are all aspheric, and the material of each of the first lens L1 to the fourth lens L4 is Plastic (PC).

The lens parameters of the optical system 10 in this embodiment are given in table 7, wherein the names and parameters of the elements can be defined in the first embodiment, which is not described herein.

TABLE 7

Table 8 below presents the aspheric coefficients of the corresponding lens surfaces in table 7, where K is the conic coefficient and Ai is the coefficient corresponding to the i-th order high-order term in the aspheric surface-type formula.

TABLE 8

As can be seen from the aberration diagrams in fig. 8, the longitudinal spherical aberration, curvature of field, astigmatism, and distortion of the optical system 10 having wide-angle characteristics are well controlled, and the optical system 10 of this embodiment can have good imaging quality.

Fifth embodiment

Referring to fig. 9, in the fifth embodiment, the optical system 10 includes, in order from the object side to the image side along the optical axis 101, a first lens element L1 with negative refractive power, a second lens element L2 with negative refractive power, a stop STO, a third lens element L3 with positive refractive power, and a fourth lens element L4 with negative refractive power. The respective lens surface types of the optical system 10 are as follows:

In the fifth embodiment, the surfaces of the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 of the first lens L1 to the fourth lens L4 are all aspheric, and the material of each of the first lens L1 to the fourth lens L4 is Plastic (PC).

The lens parameters of the optical system 10 in this embodiment are given in table 9, wherein the definitions of the names and parameters of the elements can be obtained from the first embodiment, which is not described herein.

TABLE 9

Table 10 below presents the aspherical coefficients of the corresponding lens surfaces in table 9, where K is a conic coefficient and Ai is a coefficient corresponding to the i-th order higher-order term in the aspherical surface type formula.

Watch 10

As can be seen from the aberration diagrams in fig. 10, the longitudinal spherical aberration, curvature of field, astigmatism, and distortion of the optical system 10 having the wide-angle characteristic are all controlled well, and the optical system 10 of this embodiment can have good imaging quality.

Referring to table 11, table 11 summarizes ratios of the relations in the first embodiment to the fifth embodiment of the present application.

TABLE 11

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The optical system 10 in each of the above embodiments can keep good imaging quality while compressing the total length to achieve a miniaturized design, and can also possess a large image plane characteristic, compared to a general optical system.

Referring to fig. 11, an embodiment of the present application further provides a camera module 20, where the camera module 20 includes an optical system 10 and a photosensitive chip 210, and the photosensitive chip 210 is disposed on an image side of the optical system 10, and the photosensitive chip 210 and the optical system can be fixed by a bracket. The photo sensor chip 210 may be a CCD sensor (Charge Coupled Device) or a CMOS sensor (Complementary Metal Oxide Semiconductor). Generally, the imaging surface S11 of the optical system 10 overlaps the photosensitive surface of the photosensitive chip 210 when assembled. By adopting the optical system 10 described above, the camera module 20 satisfies a miniaturized design while having a large angle of view, and at the same time can satisfy the demand for high imaging quality.

Referring to fig. 12, some embodiments of the present application further provide a terminal device 30. The terminal device 30 includes a fixing member 310, the camera module 20 is mounted on the fixing member 310, and the fixing member 310 may be a display screen, a circuit board, a middle frame, a rear cover, or the like. The terminal device 30 may be, but is not limited to, a smart phone, a smart watch, smart glasses, an e-book reader, a tablet computer, a PDA (Personal Digital Assistant), an endoscope device, and the like. The camera module 20 can satisfy the miniaturization design of the terminal device 30 with a larger field angle, and can satisfy the requirement of high imaging quality.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or to implicitly indicate the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically limited otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," and "fixed" are to be construed broadly and may, for example, be fixedly connected, detachably connected, or integrally formed; the connection can be mechanical connection, electrical connection or communication; they may be directly connected or indirectly connected through intervening media, or may be connected through the use of two elements or the interaction of two elements. The specific meaning of the above terms in the present invention can be understood according to specific situations by those skilled in the art.

In the description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Moreover, various embodiments or examples and features of various embodiments or examples described in this specification can be combined and combined by one skilled in the art without being mutually inconsistent.

While embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that: various changes, modifications, substitutions and alterations can be made to the embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the claims and their equivalents.

Claims

1. An optical system, comprising four lens elements with refractive power, in order from an object side to an image side along an optical axis:

a first lens element with negative refractive power having a convex object-side surface and a concave image-side surface;

a second lens element with negative refractive power having a concave object-side surface at paraxial region and a convex image-side surface at paraxial region;

a third lens element with positive refractive power having convex object-side and image-side surfaces at paraxial region;

a fourth lens element with negative refractive power having a concave object-side surface at a paraxial region and a convex image-side surface at a paraxial region;

the optical system satisfies the relationship:

210°/mm＜FOV/f＜300°/mm；

140°＜FOV＜150°；

FOV is the maximum field angle of the optical system, and f is the effective focal length of the optical system.

2. The optical system of claim 1, wherein the optical system satisfies the relationship:

0.05＜|f1/f2|＜0.12；

21＜|f2/f3|＜38；

0.58＜|f3/f4|＜0.65；

f1 is an effective focal length of the first lens, f2 is an effective focal length of the second lens, f3 is an effective focal length of the third lens, and f4 is an effective focal length of the fourth lens.

3. The optical system of claim 1, further comprising a stop located between an image-side surface of the second lens and an object-side surface of the third lens, the optical system satisfying the relationship:

1.45＜CT2/CT1＜2.35；

4.9＜(CT1+CT2+CT3+CT4)/(AC1+AC2+AC3)＜5.5；

CT1 is the thickness of the first lens element on the optical axis, CT2 is the thickness of the second lens element on the optical axis, CT3 is the thickness of the third lens element on the optical axis, CT4 is the thickness of the fourth lens element on the optical axis, AC1 is the air space between the first lens element and the second lens element on the optical axis, AC2 is the air space between the second lens element and the third lens element on the optical axis, and AC3 is the air space between the third lens element and the fourth lens element on the optical axis.

4. The optical system of claim 1, wherein the optical system satisfies the relationship:

f/TTL＜0.2；

0.6mm＜TTL/FNO＜0.7mm；

0.42mm＜(TTL-BFL)/FNO＜0.47mm；

TTL is the object side of first lens to optical system's image plane distance on the optical axis, FNO is optical system's f-number, BFL is fourth lens's image side to image plane distance on the optical axis.

5. The optical system of claim 1, wherein the optical system satisfies the relationship:

2.5＜Vd1/Vd2＜2.8；

2.3＜Vd3/Vd4＜2.4；

1.5＜|R42/R31|＜2；

vd1 is an abbe number of the first lens, vd2 is an abbe number of the second lens, vd3 is an abbe number of the third lens, vd4 is an abbe number of the fourth lens, R31 is a curvature radius of an object-side surface of the third lens at an optical axis, and R42 is a curvature radius of an image-side surface of the fourth lens at the optical axis.

6. The optical system of claim 1, wherein the optical system satisfies the relationship:

31°＜FOV/FNO＜33°；

0.1mm＜f/FNO＜0.15mm；

1.5mm＜|f1+f2+f3+f4|/FNO＜3mm；

FNO is an f-number of the optical system, f1 is an effective focal length of the first lens, f2 is an effective focal length of the second lens, f3 is an effective focal length of the third lens, and f4 is an effective focal length of the fourth lens.

7. The optical system of claim 1, wherein the optical system satisfies the relationship:

2.8＜(CT1+CT2+CT3+CT4)/f＜3.1；

0.35mm＜(CT1+CT2+CT3+CT4)/FNO＜0.39mm；

1.7＜(CT1+CT2+CT3+CT4)/BFL＜1.9；

CT1 is the thickness of the first lens element on the optical axis, CT2 is the thickness of the second lens element on the optical axis, CT3 is the thickness of the third lens element on the optical axis, CT4 is the thickness of the fourth lens element on the optical axis, and FNO is the f-number of the optical system; and BFL is the distance from the image side surface of the fourth lens to the imaging surface.

8. The optical system of claim 1, wherein the optical system satisfies the relationship:

13.7mm ^-1 ＜FNO/(AC1+AC2+AC3)＜14.2mm ^-1 ；

1.6＜f/(AC1+AC2+AC3)＜1.9；

0.33＜(AC1+AC2+AC3)/BFL＜0.35；

FNO does optical system's f-number, AC1 does first lens with the second lens is in the epaxial air space of optical axis, and AC2 does the second lens with the third lens is in the epaxial air space of optical axis, and AC3 does the third lens with the fourth lens is in the epaxial air space of optical axis, and BFL does the image side of fourth lens is to the distance of imaging surface on the optical axis.

9. A camera module, comprising a photosensitive chip and the optical system of any one of claims 1 to 8, wherein the photosensitive chip is disposed on an image side of the optical system.

10. A terminal device, comprising a fixing member and the camera module set according to claim 9, wherein the camera module set is disposed on the fixing member.