CN116819723A

CN116819723A - Optical system, camera module and terminal equipment

Info

Publication number: CN116819723A
Application number: CN202310492054.3A
Authority: CN
Inventors: 饭嶋健司
Original assignee: Jiangxi Oufei Optics Co ltd
Current assignee: Jiangxi Oufei Optics Co ltd
Priority date: 2023-05-04
Filing date: 2023-05-04
Publication date: 2023-09-29

Abstract

The invention discloses an optical system, a camera module and terminal equipment. The optical system comprises nine lens elements with refractive power, a first lens element with negative refractive power, a second lens element with negative refractive power, a third lens element with negative refractive power, a fourth lens element with positive refractive power, a fifth lens element with positive refractive power, a sixth lens element with positive refractive power, a seventh lens element with positive refractive power, an eighth lens element with negative refractive power and a ninth lens element with positive refractive power, which are arranged in sequence from the object side to the image side along an optical axis; the optical system satisfies the relationship: 39 (deg/mm) < FOV/f <54 (deg/mm); the optical system has a large angle of view and good imaging quality, and is favorable for acquiring more scene contents, so that imaging information of the optical system is enriched.

Description

Optical system, camera module and terminal equipment

Technical Field

The present invention relates to the field of photography imaging technology, and in particular, to an optical system, a camera module, and a terminal device.

Background

At present, with the progress of sensing technology, the pixel pitch is finer and finer, a sensor with higher pixels is required to be supported by a lens, and the shooting range of a general wide-angle lens is wide, but due to adverse factors such as distortion aberration, the peripheral area is easily compressed, and finally the amount of information which can be shot is reduced, so how to realize that an optical system has a larger angle of view and good imaging quality is simultaneously achieved, and the imaging device is one of technical problems which are urgent to be solved in the industry.

Disclosure of Invention

The present invention aims to solve at least one of the technical problems existing in the prior art. Therefore, the first aspect of the present invention provides an optical system with a larger angle of view and good imaging quality, which is favorable for the optical system to acquire more scene contents and enrich imaging information of the optical system.

The second aspect of the present invention further provides an image capturing module.

The third aspect of the present invention also proposes a terminal device.

According to the optical system of the first aspect of the present invention, the number of lenses with refractive power is nine, 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 at a paraxial region and a concave image-side surface at a paraxial region; a second lens element with negative refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; a third lens element with negative refractive power having a concave object-side surface at a paraxial region and a concave image-side surface at a paraxial region; a fourth lens element with positive refractive power having a convex object-side surface at a paraxial region and a convex image-side surface at a paraxial region; a fifth lens element with positive refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; a sixth lens element with positive refractive power having a convex object-side surface at a paraxial region and a convex image-side surface at a paraxial region; a seventh lens element with positive refractive power having a convex image-side surface at a paraxial region; an eighth lens element with negative refractive power having a concave object-side surface at a paraxial region; and a ninth lens element with positive refractive power having a convex 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 object-side surface at a paraxial region and a concave image-side surface at a paraxial region, so that the optical system is favorable for capturing large-angle light rays entering the first lens element, the effect of wide-angle image pickup is realized, and the optical system is favorable for covering a large viewing angle range; the second lens element is designed with a convex-concave surface at a paraxial region, i.e., the object-side surface is convex and the image-side surface is concave, and has negative refractive power to facilitate sharing of negative refractive power pressure of the first lens element, so as to facilitate further converging of incident light, so that high-angle light of the first lens element is smoothly incident into the second lens element at a reasonable angle, and aberration generated by the first lens element due to the high-angle light can be corrected; the third lens element with negative refractive power has a concave object-side surface and a concave image-side surface, which facilitates the widening of a light beam and the smooth transition of light rays with larger angles, and is matched with the fourth lens element with positive refractive power, wherein the object-side surface is convex and the image-side surface is convex, which facilitates the convergence of incident light rays with large angles so as to facilitate the shortening of the total length of the optical system; the fifth lens element with positive refractive power has a convex object-side surface and a concave image-side surface, so as to balance the aberration of the fourth lens element, which is difficult to correct when converging incident light rays; the sixth lens element with positive refractive power has a convex object-side surface and a convex image-side surface, so that the central and peripheral view field rays can be further converged, thereby being beneficial to the total length of the compression optical system; the seventh lens element with positive refractive power can be matched with a surface-type design with a convex image side surface, so that the focal power of the seventh lens element can be enhanced, the total length of the system of the optical system can be further shortened, the seventh lens element with negative refractive power can be matched with a surface-type design with a concave object side surface, the gentle transition of light rays can be facilitated, the image surface bending and distortion of the peripheral part of a picture can be well corrected, meanwhile, the seventh lens element with positive refractive power can be matched with the eighth lens element with negative refractive power to mutually offset aberration generated by the eighth lens element with negative refractive power, namely the eighth lens element with negative refractive power is beneficial to correcting the aberration generated by the seventh lens element with positive refractive power, and the field curvature of the optical system can be reduced; the object side surface and the image side surface of the ninth lens with positive refractive power are convex surfaces, so that the light incoming quantity of the ninth lens can be effectively controlled, the relative illuminance is increased, the brightness of an imaging surface is improved, the incident angle of incident light on the imaging surface can be reduced, the generation of chromatic aberration is reduced, and the imaging quality of an optical system is improved.

In one embodiment, the optical system satisfies the relationship:

39 (deg/mm) < FOV/f <54 (deg/mm); FOV is the maximum field angle of the optical system and f is the effective focal length of the optical system. The relation is satisfied, and the ratio of the maximum field angle to the effective focal length of the optical system can be reasonably configured, so that the view finding area of a picture is effectively improved, and the optical system has wide-angle characteristics; and simultaneously, the sensitivity of the optical system is reduced, so that the production and the assembly of the optical system are facilitated.

In one embodiment, the optical system satisfies the relationship:

0.25< f/f6<0.70; f is the effective focal length of the optical system, and f6 is the effective focal length of the sixth lens. The relation is satisfied, the sixth lens provides positive refractive power for the optical system, and the wide-angle and high-image-quality imaging of the optical system is facilitated by controlling the ratio relation between the effective focal length of the sixth lens and the effective focal length of the optical system. Exceeding the upper limit of the relation, the refractive power of the sixth lens is too strong, so that the lens surface is too bent, and stronger astigmatism and chromatic aberration are easy to generate, thereby being unfavorable for realizing the high-resolution imaging characteristic of the optical system; below the lower limit of the relation, the effective focal length of the sixth lens element is too large, and the refractive power in the middle of the optical system is insufficient, so that captured large-angle light is difficult to be smoothly incident to the rear lens group (i.e., the seventh lens element, the eighth lens element and the ninth lens element) of the optical system, which is disadvantageous in expanding the angle of view of the optical system.

In one embodiment, the optical system satisfies the relationship:

0.20< f/f9<0.60; f is the effective focal length of the optical system, and f9 is the effective focal length of the ninth lens. The ninth lens element can provide a proper positive refractive power, so as to effectively correct spherical aberration generated by the front lens element (i.e., the first lens element to the eighth lens element) and enhance the imaging resolution of the optical system; in addition, the positive refractive power can also reasonably deflect the light rays incident at a large angle, which is favorable for the size compression of the ninth lens to the whole optical system, thereby promoting the miniaturization of the optical system.

In one embodiment, the optical system satisfies the relationship:

0.7< |f3/f4| <0.9; f3 is the effective focal length of the third lens; f4 is the effective focal length of the fourth lens. The relation is satisfied, and the refractive power near the object side can be reasonably distributed by reasonably controlling the ratio of the effective focal length between the third lens and the fourth lens, so that the optical system can shoot objects at a longer distance, and the sufficient refractive power intensity can effectively converge light rays, thereby being beneficial to improving the imaging quality of the optical system.

In one embodiment, the optical system satisfies the relationship:

1.50< |f7/f8| <3.00; f7 is the effective focal length of the seventh lens; f8 is the effective focal length of the eighth lens. The above relation is satisfied, and the ratio of the effective focal length between the seventh lens and the eighth lens is reasonably controlled, so that the optical system has reasonable back focus, chromatic aberration, astigmatism and other aberration of the optical system can be corrected, and imaging quality of the optical system is improved.

In one embodiment, the optical system satisfies the relationship:

6< |r82/r81| <11; r81 is the radius of curvature of the object side surface of the eighth lens element at the optical axis; r82 is a radius of curvature of the image side surface of the eighth lens element at the optical axis. The curvature change trend of the object side surface and the image side surface of the eighth lens can be well controlled by meeting the relation, the shape of the eighth lens is further limited, the spherical aberration of the eighth lens is favorably controlled, the imaging quality of the view field on the optical axis and the imaging quality of the view field outside the optical axis cannot be obviously degraded due to the change of the contribution quantity of the spherical aberration, and the optical performance of the optical system is favorably improved.

In one embodiment, the optical system satisfies the relationship:

-3.2< r91/r92< -0.3; r91 is the radius of curvature of the object side surface of the ninth lens at the optical axis; r92 is the radius of curvature of the image side surface of the ninth lens at the optical axis. The curvature change trend of the object side surface and the image side surface of the ninth lens can be well controlled by meeting the relation, so that the thickness of the ninth lens is more gentle than the trend, the shape of the ninth lens is further limited, the spherical aberration of the ninth lens is favorably controlled, the imaging quality of the field of view on the optical axis and the field of view outside the optical axis cannot be obviously degraded due to the change of the contribution quantity of the spherical aberration, the optical performance of an optical system is favorably improved, meanwhile, the surface type of the ninth lens is more gentle, the processing and manufacturing difficulty of the ninth lens can be reduced, and the processing yield is improved.

In one embodiment, the optical system satisfies the relationship:

0.8< (CT 1/ET 1)/(CT 2/ET 2) <1.85; CT1 is the thickness of the first lens on the optical axis; CT2 is the thickness of the second lens on the optical axis; ET1 is the distance from the object side surface maximum effective light transmission aperture of the first lens to the image side surface maximum effective light transmission aperture in the optical axis direction, and ET2 is the distance from the object side surface maximum effective light transmission aperture of the second lens to the image side surface maximum effective light transmission aperture in the optical axis direction. The relation is satisfied, through controlling the center thickness and the edge thickness of the first lens, and the center thickness and the edge thickness of the second lens, the thickness ratio of the first lens to the second lens can be reasonably controlled, so that the surface bending freedom degree of the first lens and the second lens is optimized, the effective convergence of large-angle incident light rays is facilitated, the light rays passing through the first lens and the second lens have smaller deflection angles, the generation of stray light in an optical system is reduced, the excellent imaging performance can be ensured, meanwhile, the processing technology of the lenses can be optimized through reasonable surface shape change, and the design and assembly sensitivity of the first lens and the second lens is reduced.

In one embodiment, the optical system satisfies the relationship:

-0.2< (NL 8-NL 7)/r 72< -0.075; NL7 is the refractive index of the seventh lens, NL8 is the refractive index of the eighth lens, and r72 is the radius of curvature of the image side surface of the seventh lens at the optical axis. The refractive indexes of the seventh lens and the eighth lens and the curvature radius of the object side surface of the seventh lens are reasonably configured to meet the relational expression, so that smooth transition of light rays can be facilitated, and the optical performance of the optical system can be improved.

In one embodiment, the optical system satisfies the relationship:

9mm < TTL/FNO <15mm; TTL is the distance between the object side surface of the first lens and the imaging surface of the optical system on the optical axis, and FNO is the f-number of the optical system. The light flux can be reasonably configured on the premise of meeting miniaturization of the optical system, excessive exposure is not caused, the brightness of an edge view field of the optical system is not too low due to too large exposure, the risk of a dark angle is increased, influence of off-axis aberration on the system is reduced, and imaging quality is improved.

In one embodiment, the optical system satisfies the relationship:

3.3< SD11/SD61<2.5; SD11 is the maximum effective aperture of the object side surface of the first lens, and SD61 is the maximum effective aperture of the object side surface of the sixth lens. The relation is satisfied, and the ratio of the maximum effective caliber of the object side surface of the first lens to the maximum effective caliber of the object side surface of the sixth lens is limited, so that the whole size of the optical system is balanced, the optical system is contained in the lens barrel with a relatively simple structure, and the assembly yield of the optical system is improved.

In one embodiment, the optical system satisfies the relationship:

-8.50< v3-v4< -2.50; v3 is the abbe number of the third lens, and v4 is the abbe number of the fourth lens. The above relation is satisfied, which is favorable for reducing chromatic aberration generated by the third lens and the fourth lens, reducing tolerance sensitivity, and balancing the overall chromatic aberration of the optical system by controlling partial chromatic aberration; meanwhile, the third lens and the fourth lens are convenient to glue, so that the interval distance between the two lenses is reduced, and the total length of the system is reduced; the assembly parts between the lenses are reduced, so that the working procedures are reduced, and the cost is lowered; the tolerance sensitivity problem of the lens unit caused by inclination/core deviation and the like in the assembling process is reduced, and the production yield is improved.

In one embodiment, the optical system satisfies the relationship:

40.0< v7-v8<70.0, v7 is the abbe number of the seventh lens and v8 is the abbe number of the eighth lens. The above relation is satisfied, which is favorable for reducing chromatic aberration generated by the seventh lens and the eighth lens, reducing tolerance sensitivity, and balancing the overall chromatic aberration of the optical system by controlling partial chromatic aberration;

in one embodiment, the seventh lens and the eighth lens are cemented to facilitate reducing the separation distance between the two lenses, thereby reducing the overall length of the system; the assembly parts between the lenses are reduced, so that the working procedures are reduced, and the cost is lowered; the tolerance sensitivity problem of the lens unit caused by inclination/core deviation and the like in the assembling process is reduced, and the production yield is improved.

In one embodiment, the optical system satisfies the relationship:

0.15mm ^-1 <1/(f12*DST)<0.65mm ^-1 the method comprises the steps of carrying out a first treatment on the surface of the f12 is the combined effective focal length of the first lens and the second lens; DST is the amount of distortion at the maximum field angle of the optical system. The above relation is satisfied, and the effective focal length of the combination of the first lens and the second lens can be reasonably configured on the premise of satisfying the distortion in a predetermined range, so that the refractive powers of the first lens and the second lens are reasonably distributed, and the effective convergence of the incident light rays with large angles is facilitated.

The image pickup module according to the second aspect of the present invention comprises a photosensitive chip and any one of the above optical systems, wherein the photosensitive chip is disposed on an image side of the optical system. By adopting the optical system, the camera module can meet the requirement of high imaging quality while having a larger field angle.

The terminal equipment according to the third aspect of the invention comprises a fixing piece and the camera module, wherein the camera module is arranged on the fixing piece. The camera shooting module can meet the requirement of high imaging quality while having a larger 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 invention;

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

FIG. 3 is a schematic diagram of an optical system according to a second embodiment of the present invention;

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

FIG. 5 is a schematic diagram of an optical system according to a third embodiment of the present invention;

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

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

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

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

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

fig. 11 is a schematic structural view of an optical system according to a sixth embodiment of the present invention;

fig. 12 includes a longitudinal spherical aberration diagram, an astigmatic diagram, and a distortion diagram of the optical system in the sixth embodiment;

FIG. 13 is a schematic diagram of an image capturing module according to an embodiment of the present invention;

Fig. 14 is a schematic structural diagram of a terminal device according to an embodiment of the present invention.

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 surface S1, the image side surface S2,

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

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

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

fifth lens L5: the object side S9, the image side S10,

sixth lens L6: the object side S11, the image side S12,

seventh lens L7: the object side S13, the image side S14,

eighth lens L8: the object side S15, the image side S16,

ninth lens L9: the object side S17, the image side S18,

filter object side S19, filter image side S20,

the filter 110, the imaging plane S21, the terminal device 30,

a fixing member 310.

Detailed Description

Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to like or similar elements or elements having like or similar functions throughout. The embodiments described below by referring to the drawings are illustrative and intended to explain the present invention and should not be construed as limiting the invention.

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

Referring to fig. 1, an embodiment of the present invention provides an optical system 10 having a nine-lens design, wherein the optical system 10 includes, in order along an optical axis 101, a first lens L1 having negative refractive power, a second lens L2 having negative refractive power, a third lens L3 having negative refractive power, a fourth lens L4 having positive refractive power, a fifth lens L5 having positive refractive power, a sixth lens L6 having positive refractive power, a seventh lens L7 having positive refractive power, an eighth lens L8 having negative refractive power, and a ninth lens L9 having positive refractive power. The lenses in the optical system 10 should be coaxially disposed, the common axis of the lenses is the optical axis 101 of the optical system 10, and the lenses can be mounted in a lens barrel to form an imaging lens.

The first lens element L1 has an object-side surface S1 and an image-side surface S2, the second lens element L2 has an object-side surface S3 and an image-side surface S4, the third lens element L3 has an object-side surface S5 and an image-side surface S6, the fourth lens element L4 has an object-side surface S7 and an image-side surface S8, the fifth lens element L5 has an object-side surface S9 and an image-side surface S10, the sixth lens element L6 has an object-side surface S11 and an image-side surface S12, the seventh lens element L7 has an object-side surface S13 and an image-side surface S14, the eighth lens element L8 has an object-side surface S15 and an image-side surface S16, and the ninth lens element L9 has an object-side surface S17 and an image-side surface S18. Meanwhile, the optical system 10 further has an imaging surface S21, the imaging surface S21 is located at the image side of the ninth lens L9, and the light emitted from the on-axis object point at the corresponding object distance can be converged on the imaging surface S21 after being adjusted by each lens of the optical system 10.

With continued reference to fig. 13, in general, the imaging surface S21 of the optical system 10 coincides with the photosurface of the photoship 210. It should be noted that, in some embodiments, the optical system 10 may be matched to the photosensitive chip 210 having a rectangular photosensitive surface, and the imaging surface S21 of the optical system 10 coincides with the rectangular photosensitive surface of the photosensitive chip 210. At this time, the effective pixel area on the imaging surface S21 of the optical system 10 has a horizontal direction, a vertical direction, and a diagonal direction, and in the present invention, the maximum field angle of the optical system 10 may be understood as the field angle of the optical system 10 in the diagonal direction, and the image height corresponding to the maximum field angle may be understood as half the length of the effective pixel area on the imaging surface S21 of the optical system 10 in the diagonal direction.

In the embodiment of the invention, 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 convex at the paraxial region 101, and the image side surface S4 is concave at the paraxial region 101; the object side surface S5 of the third lens element L3 is concave at the paraxial region 101, and the image side surface S6 is concave at the paraxial region 101; the fourth lens element L4 has a convex object-side surface S7 at a paraxial region 101 and a convex image-side surface S8 at the paraxial region 101; the object side surface S9 of the fifth lens element L5 is convex at the paraxial region 101, and the image side surface S10 is concave at the paraxial region 101; the object side surface S11 of the sixth lens element L6 is convex at the paraxial region 101, and the image side surface S12 is convex at the paraxial region 101; the image-side surface S14 of the seventh lens element L7 is convex at the paraxial region 101; the object side surface S15 of the eighth lens element L8 is concave at the paraxial region 101; the object side surface S17 of the ninth lens element L9 is convex at the paraxial region 101, and the image side surface S18 is convex at the paraxial region 101; when describing that the lens surface has a certain profile at the paraxial region 101, i.e. that the lens surface has such a profile near the optical axis 101.

In the optical system 10, the first lens element L1 with negative refractive power has a convex object-side surface S1 at a paraxial region and a concave image-side surface S2 at a paraxial region, so as to facilitate capturing of a large-angle light beam incident into the first lens element L1, thereby realizing a wide-angle image capturing effect and facilitating coverage of a wide viewing angle range by the optical system 10; the second lens element L2 has a convex-concave design at a paraxial region, i.e., the object-side surface S3 is convex and the image-side surface S4 is concave, and has negative refractive power to facilitate sharing of the negative refractive power of the first lens element L1, so as to facilitate further converging the incident light, so that the large-angle light of the first lens element L1 is smoothly incident into the second lens element L2 at a reasonable angle, and meanwhile, aberration generated by the large-angle light of the first lens element L1 can be corrected; the third lens element L3 with negative refractive power has a concave object-side surface S5 and a concave image-side surface S6, which are beneficial to widening a beam bundle and smoothly transiting light rays with larger angle, and the fourth lens element L4 with positive refractive power has a convex object-side surface S7 and a convex image-side surface S8, which are beneficial to converging incident light rays with larger angle so as to be beneficial to shortening the total system length of the optical system 10, and the third lens element L3 with negative refractive power and the fourth lens element L4 with positive refractive power can mutually offset aberration generated by each other, i.e. the fourth lens element L4 with positive refractive power is beneficial to correcting the aberration generated by the third lens element L3 with negative refractive power, thereby reducing the field curvature of the optical system 10; the fifth lens element L5 with positive refractive power has a convex object-side surface S9 and a concave image-side surface S10, so as to balance the aberrations of the fourth lens element L4, which are difficult to correct when converging the incident light rays; the sixth lens element L6 with positive refractive power having a convex object-side surface S11 and a convex image-side surface S12, which further converges the central and peripheral field-of-view rays, thereby facilitating the overall length of the optical system 10; the seventh lens element L7 with positive refractive power can enhance the focal power of the seventh lens element L7 with the convex surface of the image-side surface S13, which is beneficial to further shortening the overall length of the optical system 10, and the eighth lens element L8 with negative refractive power can be matched with the concave surface of the object-side surface S15 of the eighth lens element L8, which is beneficial to smooth transition of light rays, and can better correct the curvature and distortion of the image plane at the peripheral part of the image, meanwhile, the seventh lens element L7 with positive refractive power can mutually offset the aberration generated by each other with the eighth lens element L8 with negative refractive power, i.e. the eighth lens element L8 with negative refractive power is beneficial to correct the aberration generated by the seventh lens element L7 with positive refractive power, thereby reducing the curvature of field of the optical system 10; the object side surface S17 and the image side surface S18 of the ninth lens element L9 with positive refractive power are convex, so as to effectively control the light entering amount, thereby increasing the relative illuminance, improving the brightness of the imaging surface S21, reducing the incident angle of the incident light on the imaging surface S21, and reducing the chromatic aberration, so as to improve the imaging quality of the optical system 10.

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

39 (deg/mm) < FOV/f <54 (deg/mm); FOV is the maximum field angle of the optical system 10 and f is the effective focal length of the optical system 10. The ratio of the maximum field angle to the effective focal length of the optical system 10 can be reasonably configured by satisfying the above relation, so that the viewing area of a picture is effectively increased, and the optical system 10 has wide-angle characteristics; while also facilitating a reduction in sensitivity of the optical system 10, thereby facilitating production and assembly of the optical system 10.

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

0.25< f/f6<0.70; f is the effective focal length of the optical system, and f6 is the effective focal length of the sixth lens L6. The sixth lens element L6 provides positive refractive power for the optical system 10, and the optical system 10 can achieve wide-angle and high-quality imaging by controlling the ratio of the effective focal length of the sixth lens element L6 to the effective focal length of the optical system 10. Exceeding the upper limit of the relation, the refractive power of the sixth lens element L6 is too strong, resulting in excessive bending of the lens surface, which is prone to generate stronger astigmatism and chromatic aberration, thereby being unfavorable for realizing the high resolution imaging characteristics of the optical system 10; below the lower limit of the relationship, the effective focal length of the sixth lens element L6 is too large, and the refractive power in the middle of the optical system is insufficient, so that it is difficult for captured large-angle light rays to smoothly enter the rear lens group (i.e., the seventh lens element L7, the eighth lens element L8, and the ninth lens element L9) of the optical system 10, thereby being disadvantageous in expanding the angle-of-view range of the optical system 10.

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

0.20< f/f9<0.60; f is the effective focal length of the optical system 10, and f9 is the effective focal length of the ninth lens L9. Satisfying the above relation, the ninth lens element L9 can provide a proper positive refractive power, and can effectively correct spherical aberration generated by the front lens element group (i.e., the first lens element L1 to the eighth lens element L8), thereby enhancing the imaging resolution of the optical system 10; in addition, the positive refractive power can also reasonably deflect the light incident at a large angle, which is beneficial to the size compression of the ninth lens element L9 on the whole optical system 10, thereby promoting the miniaturization of the optical system 10.

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

0.7< |f3/f4| <0.9; f3 is the effective focal length of the third lens L3; f4 is the effective focal length of the fourth lens L4. The above relation is satisfied, and the refractive power near the object side is reasonably distributed by reasonably controlling the ratio of the effective focal lengths between the third lens element L3 and the fourth lens element L4, so that the optical system 10 can shoot objects at a longer distance, and the sufficient refractive power intensity can effectively converge light rays, thereby being beneficial to improving the imaging quality of the optical system 10.

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

1.50< |f7/f8| <3.00; f7 is the effective focal length of the seventh lens L7; f8 is the effective focal length of the eighth lens L8. Satisfying the above relation, the ratio of the effective focal length between the seventh lens L7 and the eighth lens L8 can be reasonably controlled, which is beneficial to making the optical system 10 have a reasonable back focus, being beneficial to correcting chromatic aberration, astigmatism and other aberrations of the optical system 10, and improving the imaging quality of the optical system 10.

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

6< |r82/r81| <11; r81 is a radius of curvature of the object side surface S15 of the eighth lens L8 at the optical axis; r82 is a radius of curvature of the image side surface S16 of the eighth lens L8 at the optical axis. The curvature change trend of the object side surface S15 and the image side surface S16 of the eighth lens element L8 can be well controlled by satisfying the above relation, so that the shape of the eighth lens element L8 is limited, the spherical aberration of the eighth lens element L8 is favorably controlled, the imaging quality of the field of view on the optical axis and the field of view outside the optical axis cannot be obviously degraded due to the change of the contribution amount of the spherical aberration, and the optical performance of the optical system 10 is favorably improved.

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

-3.2< r91/r92< -0.3; r91 is the radius of curvature of the object side surface S17 of the ninth lens L9 at the optical axis; r92 is the radius of curvature of the image side surface S18 of the ninth lens L9 at the optical axis. The curvature change trend of the object side surface S17 and the image side surface S18 of the ninth lens element L9 can be well controlled by satisfying the above relation, so that the thickness of the ninth lens element L9 is smoother than the trend, the shape of the ninth lens element L9 is further limited, the spherical aberration of the ninth lens element L9 is favorably controlled, the imaging quality of the field of view on the optical axis and the field of view outside the optical axis cannot be obviously degraded due to the contribution change of the spherical aberration, the optical performance of the optical system 10 is favorably improved, the surface change of the ninth lens element L9 is gentle, the processing and manufacturing difficulty of the ninth lens element L9 can be reduced, and the processing yield is improved.

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

0.8< (CT 1/ET 1)/(CT 2/ET 2) <1.85; CT1 is the thickness of the first lens L1 on the optical axis; CT2 is the thickness of the second lens L2 on the optical axis; ET1 is the distance from the position of the object side surface S1 with the largest effective aperture of the first lens element L1 to the position of the image side surface with the largest effective aperture of the second lens element L2 in the optical axis direction, and ET2 is the distance from the position of the object side surface S3 with the largest effective aperture of the second lens element L2 to the position of the image side surface with the largest effective aperture of the second lens element L2 in the optical axis direction. The above relation is satisfied, by controlling the center thickness and the edge thickness of the first lens L1 and the center thickness and the edge thickness of the second lens L2, the thickness ratio of the first lens L1 to the second lens L2 can be reasonably controlled, so that the planar bending degrees of freedom of the first lens L1 and the second lens L2 are optimized, thereby being beneficial to the effective convergence of the incident light rays with a large angle, and the light rays passing through the first lens L1 and the second lens L2 have a smaller deflection angle, thereby reducing the generation of stray light in the optical system 10, further ensuring excellent imaging performance, and meanwhile, the reasonable planar change can optimize the processing technology of the lenses, and reduce the design and assembly sensitivity of the first lens L1 and the second lens L2.

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

-0.2< (NL 8-NL 7)/r 72< -0.075; NL7 is the refractive index of the seventh lens L7, NL8 is the refractive index of the eighth lens L8, and r72 is the radius of curvature of the image side surface S13 of the seventh lens L7 at the optical axis. Satisfying the above relation, by reasonably configuring the refractive indexes of the seventh lens L7 and the eighth lens L8 and the radius of curvature of the object-side surface S13 of the seventh lens L7, smooth transition of light rays can be facilitated, and improvement of the optical performance of the optical system 10 can be facilitated.

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

9mm < TTL/FNO <15mm; TTL is the distance between the object side surface S1 of the first lens L1 and the imaging surface S21 of the optical system 10 on the optical axis, and FNO is the f-number of the optical system 10. The above relation is satisfied, and the light quantity can be reasonably configured on the premise of satisfying miniaturization of the optical system 10, so that excessive exposure is not caused, the edge view field of the optical system is not too low due to too large exposure, the risk of dark angle is increased, the influence of off-axis aberration on the system is reduced, and the imaging quality is improved.

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

3.3< SD11/SD61<2.5; SD11 is the maximum effective aperture of the object side surface S1 of the first lens L1, and SD61 is the maximum effective aperture of the object side surface S11 of the sixth lens L6. The above relation is satisfied, and the ratio of the maximum effective caliber of the object side surface S1 of the first lens L1 to the maximum effective caliber of the object side surface S11 of the sixth lens L6 is defined, so that the overall size of the optical system 10 is balanced, which is beneficial to accommodating the optical system 10 in a lens barrel with a relatively simple structure and improving the assembly yield of the optical system 10.

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

-8.50< v3-v4< -2.50; v3 is the abbe number of the third lens L3, and v4 is the abbe number of the fourth lens L4. Satisfying the above relation is beneficial to reducing chromatic aberration generated by the third lens L3 and the fourth lens L4, reducing tolerance sensitivity, and balancing the overall chromatic aberration of the optical system 10 by controlling partial chromatic aberration; meanwhile, the third lens L3 and the fourth lens L4 are convenient to glue, and the interval distance between the two lenses is reduced, so that the total length of the system is reduced; the assembly parts between the lenses are reduced, so that the working procedures are reduced, and the cost is lowered; the tolerance sensitivity problem of the lens unit caused by inclination/core deviation and the like in the assembling process is reduced, and the production yield is improved.

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

40.0< v7-v8<70.0; v7 is the abbe number of the seventh lens L7, and v8 is the abbe number of the eighth lens L8. Satisfying the above relation is advantageous in reducing chromatic aberration generated by the seventh lens L7 and the eighth lens L8, reducing tolerance sensitivity, balancing the overall chromatic aberration of the optical system 10 by controlling partial chromatic aberration;

in one embodiment, the seventh lens L7 and the eighth lens L8 are glued to facilitate reducing the separation distance between the two lenses, thereby reducing the overall length of the system; the assembly parts between the lenses are reduced, so that the working procedures are reduced, and the cost is lowered; the tolerance sensitivity problem of the lens unit caused by inclination/core deviation and the like in the assembling process is reduced, and the production yield is improved.

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

0.15mm ^-1 <1/(f12*DST)<0.65mm ^-1 the method comprises the steps of carrying out a first treatment on the surface of the f12 is the combined effective focal length of the first lens L1 and the second lens L2; DST is the amount of distortion at the maximum field angle of the optical system 10. The above relation is satisfied, and the combined effective focal length of the first lens L1 and the second lens L2 can be reasonably configured on the premise of satisfying the distortion in the predetermined range, so that the refractive powers of the first lens L1 and the second lens L2 are reasonably distributed, and the effective convergence of the incident light rays with large angles is facilitated.

The effective focal length is at least a value corresponding to the lens element at the paraxial region 101, and the refractive power of the lens element is at least a value corresponding to the paraxial region 101. The above relational conditions and the technical effects thereof are directed to the optical system 10 having the lens design described above. If the lens design (lens number, refractive power configuration, surface configuration, etc.) of the optical system 10 cannot be ensured, it is difficult to ensure that the optical system 10 still has the technical effects when satisfying these relationships, 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 of manufacturing the lens and reduce the manufacturing cost.

In some embodiments, at least one lens of the optical system 10 may also have an aspherical surface profile, i.e., when at least one side surface (object side or image side) of the lens is aspherical, the lens may be said to have an aspherical surface profile. In one embodiment, both the object side and the image side of each lens can be designed to be aspheric. The aspheric design can help the optical system 10 to more effectively eliminate aberrations and improve imaging quality. In some embodiments, in order to achieve the advantages of manufacturing cost, manufacturing difficulty, imaging quality, assembly difficulty, etc., the design of each lens surface in the optical system 10 may be composed of a spherical and an aspherical surface profile.

The surface type calculation of the aspherical surface can refer to an aspherical surface formula:

where Z is the distance from the corresponding point on the aspheric surface to the tangential plane of the surface at the optical axis 101, r is the distance from the corresponding point on the aspheric surface to the optical axis 101, c is the curvature of the aspheric surface at the optical axis 101, k is the conic coefficient, ai is the higher order term coefficient corresponding to the i-th order higher order term in the aspheric surface formula.

It should further be noted that when a certain lens surface is aspherical, there may be a point of inflection on the lens surface, where a change in the type of surface will occur in the radial direction, e.g. one lens surface is convex at the paraxial region 101 and concave near the maximum effective caliber. The surface shape design of the inflection point can realize good correction of curvature of field and distortion aberration of the fringe field in the optical system 10, and improve imaging quality.

In some embodiments, the material of at least one lens in the optical system 10 is Glass (GL). For example, the first lens L1 closest to the object side may be made of a glass material, and the influence of the environmental temperature change on the optical system 10 may be effectively reduced by using the temperature-eliminating and drift effect of the glass material of the first lens L1, so as to maintain a better and stable imaging quality. In some embodiments, the material of at least one lens in the optical system 10 may also be Plastic (PC), which may be polycarbonate, gum, or the like. The lens with plastic material can reduce the production cost of the optical system 10, while the lens with glass material can withstand 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, i.e. a combination of glass lenses and plastic lenses may be used, but the specific configuration relationship may be determined according to practical requirements, which is not meant to be exhaustive.

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, where the two or more lenses can form a cemented lens, a surface of the cemented lens closest to the object side may be referred to as an object side surface S1, and a surface closest to the image side may be referred to as an image side surface S2. Alternatively, the first lens L1 does not have a cemented lens, but the distance between the lenses is relatively constant, and 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, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, or the ninth lens L9 in some embodiments may be greater than or equal to two, and any adjacent lenses may form a cemented lens therebetween or may be a non-cemented lens.

In some embodiments, the aperture stop ST0 of the present invention may be an aperture stop, or a field stop, and the aperture stop is used for controlling the light entering amount and the depth of field of the optical system 10, and meanwhile, can well intercept the non-effective 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 S1 of the first lens L1. It is to be understood that, in other embodiments, the stop STO may 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, or between the fourth lens L4 and the fifth lens L5, or between the fifth lens L5 and the sixth lens L6, or between the sixth lens L6 and the seventh lens L7, or between the seventh lens L7 and the eighth lens L8, or between the eighth lens L8 and the ninth lens L9, and the arrangement is adjusted according to the actual situation, which is not particularly limited in the embodiments of the present invention. The aperture stop STO may also be formed by a holder that holds the lens.

The optical system 10 of the present invention 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 L1 with negative refractive power, a second lens L2 with negative refractive power, a third lens L3 with negative refractive power, a fourth lens L4 with positive refractive power, a fifth lens L5 with positive refractive power, a stop STO, a sixth lens L6 with positive refractive power, a seventh lens L7 with positive refractive power, an eighth lens L8 with negative refractive power, and a ninth lens L9 with positive refractive power. The lens surfaces 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 convex at the paraxial region 101, and the image side surface S4 is concave at the paraxial region 101;

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

the fourth lens element L4 has a convex object-side surface S7 at a paraxial region 101 and a convex image-side surface S8 at the paraxial region 101;

the object side surface S9 of the fifth lens element L5 is convex at the paraxial region 101, and the image side surface S10 is concave at the paraxial region 101;

the object side surface S11 of the sixth lens element L6 is convex at the paraxial region 101, and the image side surface S12 is convex at the paraxial region 101;

The image-side surface S13 of the seventh lens element L7 is convex at the paraxial region 101; the image side surface S14 is convex at the paraxial region 101;

the object side surface S15 of the eighth lens element L8 is concave at the paraxial region 101; the image side surface S16 is concave at the paraxial region 101;

the object-side surface S17 of the ninth lens element L9 is convex at the paraxial region 101, and the image-side surface S18 is convex at the paraxial region 101.

Further, in the present embodiment, the stop STO is an aperture stop, and is located between the image side surface S10 of the fifth lens element L5 and the object side surface S11 of the sixth lens element L6. In the first embodiment, the surfaces of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the seventh lens L7, and the eighth lens L8 of the first to ninth lenses L9 are spherical surfaces, the surfaces of the fifth lens L5, the sixth lens L6, and the ninth lens L9 are aspherical surfaces, and the materials of the lenses of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, and the ninth lens L9 are Glass (GL, glass).

The optical system 10 further includes a filter 110, the filter 110 being either part of the optical system 10 or removable from the optical system 10, but the total optical length TTL of the optical system 10 remains unchanged when the filter 110 is removed; the filter 110 may be an infrared cut-off filter, which is disposed between the image side surface S8 of the fourth lens L4 and the imaging surface S21 of the optical system 10, so as to filter light rays in an invisible band, 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 optical filter 110 can also filter out light rays of other wavebands, such as visible light, and only let infrared light pass through, and the optical system 10 can be used as an infrared optical lens, i.e. the optical system 10 can also image in dim environments and other special application scenarios and can obtain better image effect.

The lens parameters of the optical system 10 in the first embodiment are presented in table 1 below. The elements from the object side to the image side of the optical system 10 are sequentially arranged in the order from top to bottom of table 1, wherein the aperture stop STO characterizes the aperture stop. The radius Y 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 element L1, the surface with the surface number S2 represents the image side surface of the first lens element L1, and so on. The absolute value of the first value of the lens in the "thickness" parameter row 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 of the lens to the subsequent optical surface (the object side of the subsequent lens or the aperture plane) on the optical axis 101, wherein the thickness parameter of the aperture represents the distance from the aperture plane to the object side of the adjacent lens on the optical axis 101. The refractive index and Abbe number of each lens in the table are 587.56nm, the reference wavelength of the lens focal length is 546nm, and the numerical units of the Y radius, thickness and focal length (effective focal length) are millimeters (mm). In addition, the parameter data and the lens surface type structure used for the relational computation in the following embodiments are based on the data in the lens parameter table in the corresponding embodiments.

TABLE 1

As is clear from table 1, the effective focal length f of the optical system 10 in the first embodiment is 3.837mm, the f-number FNO is 2.0, the maximum field angle FOV of the optical system 10 is 151.7 °, the total optical length TTL is 29.493mm, 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 S21.

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 astigmatic and aberrational maps is 546nm. The longitudinal spherical aberration diagram (Longitudinal Spherical Aberration) shows the focus deviation of light rays with different wavelengths after passing through the lens. The ordinate of the longitudinal spherical aberration diagram represents the normalized pupil coordinates (Normalized Pupil Coordinator) from the pupil center to the pupil edge, and the abscissa represents the distance (in mm) from the imaging surface S21 to the intersection of the light ray with the optical axis 101. As can be seen from the longitudinal spherical aberration chart, the degree of focus deviation of the light beams with each wavelength in the first embodiment tends to be uniform, the maximum focus deviation of each reference wavelength is controlled within ±0.025mm, and the diffuse spots or the halos in the imaging picture are effectively suppressed for the optical system 10.

Fig. 2 also includes an astigmatism diagram (Astigmatic Field Curves) of the optical system 10, with the abscissa representing the distance (in mm) from the imaging surface S21 to the intersection of the light ray with the optical axis 101, and the ordinate representing the maximum field angle (in deg) of the optical system 10, where the S-curve represents the sagittal field curvature at 546nm and the T-curve represents the meridional field curvature at 546 nm. As can be seen from the figure, the curvature of field of the optical system 10 is small, the maximum curvature of field is controlled within ±0.025mm, the curvature of field is effectively suppressed for the optical system 10, the curvature of field of the sagittal field and the curvature of field under each field of view tend to be consistent, and the astigmatism of each field of view is better controlled, so that the center to the edge of the field of view of the optical system 10 has clear imaging.

Fig. 2 also includes a distortion chart of the optical system 10, in which the abscissa represents distortion (in%) and the ordinate represents the maximum angle of view (in deg) of the optical system 10, and it is understood from the distortion chart that the degree of distortion of the optical system 10 having a large angle of view characteristic is also well controlled.

Second embodiment

Referring to fig. 3, in the second embodiment, the optical system 10 includes, in order from an object side to an image side along an optical axis 101, a first lens L1 with negative refractive power, a second lens L2 with negative refractive power, a third lens L3 with negative refractive power, a fourth lens L4 with positive refractive power, a fifth lens L5 with positive refractive power, a stop STO, a sixth lens L6 with positive refractive power, a seventh lens L7 with positive refractive power, an eighth lens L8 with negative refractive power, and a ninth lens L9 with positive refractive power. The lens surfaces of the optical system 10 are as follows:

Further, in the present embodiment, the stop STO is an aperture stop, and is located between the image side surface S10 of the fifth lens element L5 and the object side surface S11 of the sixth lens element L6.

In the first embodiment, the surfaces of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the seventh lens L7, and the eighth lens L8 of the first to ninth lenses L9 are spherical surfaces, the surfaces of the fifth lens L5, the sixth lens L6, and the ninth lens L9 are aspherical surfaces, and the materials of the lenses of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, and the ninth lens L9 are Glass (GL, glass).

The parameters of each lens of the optical system 10 are given in table 3, wherein the reference wavelength of the focal length of the lens is 546nm, and the names and parameters of other elements can be defined in the first embodiment, which is not described herein.

TABLE 3 Table 3

As is clear from table 3, the effective focal length f of the optical system 10 in the second embodiment is 3.739mm, the f-number FNO is 2.0, the maximum field angle FOV of the optical system 10 is 151.7 °, the total optical length TTL is 28.528mm, 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 S21.

Table 4 below presents the aspherical 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 higher order term in the aspherical surface type formula.

TABLE 4 Table 4

As can be seen from the longitudinal spherical aberration diagram, the astigmatic diagram and the distortion diagram in fig. 4, the longitudinal spherical aberration, the field curvature, the astigmatic and the distortion of the optical system 10 having the large angle of view characteristic are well controlled, 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 L1 with negative refractive power, a second lens L2 with negative refractive power, a third lens L3 with negative refractive power, a fourth lens L4 with positive refractive power, a fifth lens L5 with positive refractive power, a stop STO, a sixth lens L6 with positive refractive power, a seventh lens L7 with positive refractive power, an eighth lens L8 with negative refractive power, and a ninth lens L9 with positive refractive power. The lens surfaces of the optical system 10 are as follows:

The parameters of each lens of the optical system 10 in this embodiment are given in table 5, wherein the reference wavelength of the focal length of the lens is 546nm, and the names and parameters of other elements can be defined in the first embodiment, which is not described herein.

TABLE 5

As is clear from table 5, the effective focal length f of the optical system 10 in the third embodiment is 3.786mm, the f-number FNO is 2.0, the maximum field angle FOV of the optical system 10 is 150.9 °, the total optical length TTL is 29.953mm, 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 S21.

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 large angle of field characteristic are well controlled, 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 L1 with negative refractive power, a second lens L2 with negative refractive power, a third lens L3 with negative refractive power, a fourth lens L4 with positive refractive power, a fifth lens L5 with positive refractive power, a stop STO, a sixth lens L6 with positive refractive power, a seventh lens L7 with positive refractive power, an eighth lens L8 with negative refractive power, and a ninth lens L9 with positive refractive power, which are sequentially included in the optical system 10 from the object side to the image side along the optical axis 101. The lens surfaces of the optical system 10 are as follows:

the image-side surface S13 of the seventh lens element L7 is concave at the paraxial region 101; the image side surface S14 is convex at the paraxial region 101;

In the first embodiment, the surfaces of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the seventh lens L7, and the eighth lens L8 of the first lens L1 to the ninth lens L9 are spherical surfaces, the surfaces of the fifth lens L5 and the sixth lens L6 are aspherical surfaces, and the materials of the lenses of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, and the ninth lens L9 are Glass (GL, glass).

The parameters of each lens of the optical system 10 in this embodiment are given in table 7, wherein the reference wavelength of the focal length of the lens is 546nm, and the names and parameters of other elements can be defined in the first embodiment, which is not described herein.

TABLE 7

As is clear from table 7, the effective focal length f of the optical system 10 in the fourth embodiment is 2.771mm, the f-number FNO is 2.4, the maximum field angle FOV of the optical system 10 is 142.3 °, the total optical length TTL is 24.999mm, 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 S21.

Table 8 below presents the aspherical coefficients of the corresponding lens surfaces in table 7, 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 8

Face number	S9	S10	S11	S12	S18
						k	0.0000E+00	0.0000E+00	0.0000E+00	0.0000E+00	0.0000E+00
A4	6.6988E-04	1.8685E-03	1.4949E-03	1.7583E-03	2.8771E-03
						A6	2.8911E-05	6.5666E-05	-2.8277E-04	-1.4669E-04	-1.0643E-04
A8	-1.0353E-06	-1.6026E-06	2.2047E-04	-5.8356E-05	4.5647E-05
						A10	5.1087E-07	6.5836E-07	-1.5445E-04	1.6649E-05	-7.1357E-06
A12	-1.0312E-07	-7.6181E-08	5.3451E-05	-5.5359E-06	7.6370E-07
						A14	9.8194E-09	9.0901E-09	-9.8270E-06	7.3136E-07	-4.3967E-08
A16	-3.6008E-10	-5.4814E-10	6.8774E-07	-6.3290E-08	1.0681E-09

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 the large angle of field characteristic 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 L1 with negative refractive power, a second lens L2 with negative refractive power, a third lens L3 with negative refractive power, a fourth lens L4 with positive refractive power, a fifth lens L5 with positive refractive power, a stop STO, a sixth lens L6 with positive refractive power, a seventh lens L7 with positive refractive power, an eighth lens L8 with negative refractive power, and a ninth lens L9 with positive refractive power. The lens surfaces of the optical system 10 are as follows:

In the first embodiment, the object side surfaces S17 of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the seventh lens L7, the eighth lens L8, and the ninth lens L9 are spherical surfaces, the image side surfaces S18 of the fifth lens L5, the sixth lens L6, and the ninth lens L9 are aspherical surfaces, and the materials of the lenses of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, the eighth lens L8, and the ninth lens L9 are Glass (GL, glass).

The parameters of each lens of the optical system 10 in this embodiment are given in table 9, wherein the reference wavelength of the focal length of the lens is 546nm, and the names and parameters of other elements can be defined in the first embodiment, which is not described herein.

TABLE 9

As is clear from table 9, the effective focal length f of the optical system 10 in the fifth embodiment is 3.057mm, the f-number FNO is 2.4, the maximum field angle FOV of the optical system 10 is 150.8 °, the total optical length TTL is 24.001mm, 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 S21.

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.

Table 10

Face number	S9	S10	S11	S12	S18
						k	0.0000E+00	0.0000E+00	0.0000E+00	0.0000E+00	0.0000E+00
A4	6.5570E-04	2.6451E-03	9.2187E-04	1.3269E-03	1.0367E-03
						A6	4.9979E-05	1.5716E-04	-4.2953E-04	-1.8818E-04	-8.1173E-06
A8	-3.5289E-06	1.8789E-05	4.8701E-04	1.8467E-04	5.8421E-06
						A10	9.8304E-07	-4.3941E-06	-2.5900E-04	-9.0350E-05	-8.9037E-07
A12	-1.0517E-07	1.5683E-06	7.7442E-05	2.5082E-05	8.0601E-08
						A14	6.6070E-09	-2.1147E-07	-1.2072E-05	-3.5840E-06	-3.9326E-09
A16	-1.8124E-10	1.2897E-08	7.6707E-07	2.0797E-07	7.9048E-11

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 large angle of field characteristic are well controlled, and the optical system 10 of this embodiment can have good imaging quality.

Sixth embodiment

Referring to fig. 10, 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 L1 with negative refractive power, a second lens L2 with negative refractive power, a third lens L3 with negative refractive power, a fourth lens L4 with positive refractive power, a fifth lens L5 with positive refractive power, a stop STO, a sixth lens L6 with positive refractive power, a seventh lens L7 with positive refractive power, an eighth lens L8 with negative refractive power, and a ninth lens L9 with positive refractive power. The lens surfaces of the optical system 10 are as follows:

the object side surface S15 of the eighth lens element L8 is concave at the paraxial region 101; the image side surface S16 is convex at the paraxial region 101;

In the first embodiment, the first lens element L1, the second lens element L2, the third lens element L3, the fourth lens element L4, the image-side surface S10 of the fifth lens element L5, the seventh lens element L7, the eighth lens element L8, and the object-side surface S17 of the ninth lens element L9 of the first through ninth lens elements L1-9 are spherical, the object-side surface S9 of the fifth lens element L5, the sixth lens element L6, and the image-side surface S18 of the ninth lens element L9 are aspherical, and the first lens element L1, the second lens element L2, the third lens element L3, the fourth lens element L4, the fifth lens element L5, the sixth lens element L6, the seventh lens element L7, the eighth lens element L8, and the ninth lens element L9 are Glass (GL, glass).

In the present embodiment, the parameters of each lens of the optical system 10 are given in table 11, wherein the reference wavelength of the focal length of the lens is 555nm, and the names and parameters of other elements can be defined in the first embodiment, which is not described herein.

TABLE 11

As is clear from table 11, the effective focal length f of the optical system 10 in the sixth embodiment is 3.058mm, the f-number FNO is 2.4, the maximum field angle FOV of the optical system 10 is 150.0 °, the total optical length TTL is 23.5mm, 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 S21.

Table 12 below presents the aspherical coefficients of the corresponding lens surfaces in table 11, 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 12

Referring to table 13, table 13 is a summary of the ratios of the relationships in the first to sixth embodiments of the present invention.

TABLE 13

Referring to fig. 13, an embodiment of the present invention further provides an image capturing module 20, where the image capturing 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 two can be fixed by a bracket. The photo-sensing chip 210 may be a CCD sensor (Charge Coupled Device ) or a CMOS sensor (Complementary Metal Oxide Semiconductor, complementary metal oxide semiconductor). Generally, at the time of assembly, the imaging surface S21 of the optical system 10 overlaps the photosensitive surface of the photosensitive chip 210. By adopting the optical system 10, the camera module 20 can meet the requirement of high imaging quality while having a larger field angle.

Referring to fig. 14, some embodiments of the present invention also provide a terminal device 30. The terminal device 30 includes a fixing member 310, and the camera module 20 is mounted on the fixing member 310, where the fixing member 310 may be a display screen, a circuit board, a middle frame, a rear cover, and the like. The terminal device 30 may be, but is not limited to, a vehicle, a smart phone, a smart watch, smart glasses, an electronic book reader, a tablet computer, a PDA (Personal Digital Assistant ), an endoscopic device, etc. The camera module 20 can meet the requirement of high imaging quality while having a larger field angle for the terminal device 30.

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

In the present invention, unless explicitly specified and limited otherwise, the terms "mounted," "connected," "secured," and the like are to be construed broadly, and may be, for example, fixedly connected, detachably connected, or integrally formed; the device can be mechanically connected, electrically connected and communicated; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present invention can be understood by those of ordinary skill in the art according to the specific circumstances.

In the description of the present specification, a description referring to terms "one embodiment," "some embodiments," "examples," "specific examples," or "some examples," etc., means 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 present invention. In this specification, schematic representations of the above terms are not necessarily directed 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. Furthermore, the different embodiments or examples described in this specification and the features of the different embodiments or examples may be combined and combined by those skilled in the art without contradiction.

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

Claims

1. An optical system, characterized in that the number of lenses with refractive power is nine, and the optical system sequentially comprises, 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 at a paraxial region and a concave image-side surface at a paraxial region;

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

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

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

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

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

a seventh lens element with positive refractive power having a convex image-side surface at a paraxial region;

an eighth lens element with negative refractive power having a concave object-side surface at a paraxial region;

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

The optical system satisfies the relationship:

39(deg/mm)<FOV/f<54(deg/mm)；

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:

0.25<f/f6<0.70；0.20<f/f9<0.60；

f6 is the effective focal length of the sixth lens; f9 is the effective focal length of the ninth lens.

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

0.7<|f3/f4|<0.9；1.50<|f7/f8|<3.00；

f3 is the effective focal length of the third lens; f4 is the effective focal length of the fourth lens; f7 is the effective focal length of the seventh lens; f8 is the effective focal length of the eighth lens.

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

6<|r82/r81|<11；-3.2<r91/r92<-0.3；

r81 is the radius of curvature of the object side surface of the eighth lens element at the optical axis; r82 is a radius of curvature of the image side surface of the eighth lens element at the optical axis, and r91 is a radius of curvature of the object side surface of the ninth lens element at the optical axis; r92 is the radius of curvature of the image side surface of the ninth lens at the optical axis.

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

0.8<(CT1/ET1)/(CT2/ET2)<1.85；

CT1 is the thickness of the first lens on the optical axis; CT2 is the thickness of the second lens on the optical axis; ET1 is the distance from the object side surface maximum effective light transmission aperture of the first lens to the image side surface maximum effective light transmission aperture in the optical axis direction, and ET2 is the distance from the object side surface maximum effective light transmission aperture of the second lens to the image side surface maximum effective light transmission aperture in the optical axis direction.

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

-0.2<(NL8-NL7)/r72<-0.075；

NL7 is the refractive index of the seventh lens, NL8 is the refractive index of the eighth lens, and r72 is the radius of curvature of the image side surface of the seventh lens at the optical axis.

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

9mm<TTL/FNO<15mm；

TTL is the distance between the object side surface of the first lens and the imaging surface of the optical system on the optical axis, and FNO is the f-number of the optical system.

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

3.3<SD11/SD61<2.5；

SD11 is the maximum effective aperture of the object side surface of the first lens, and SD61 is the maximum effective aperture of the object side surface of the sixth lens.

9. An imaging 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 of claim 9, wherein the camera module is disposed on the fixing member.