CN113552696B

CN113552696B - Optical system, image capturing module and electronic equipment

Info

Publication number: CN113552696B
Application number: CN202110800456.6A
Authority: CN
Inventors: 杨健; 华露; 李明
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2021-07-15
Filing date: 2021-07-15
Publication date: 2023-11-07
Anticipated expiration: 2041-07-15
Also published as: CN113552696A

Abstract

The invention relates to an optical system, an image capturing module and electronic equipment. The optical system includes: the first lens element with positive refractive power has a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; the second 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; a third lens element, a fourth lens element, a fifth lens element and a sixth lens element with refractive power; the seventh lens element with refractive power has a concave image-side surface at a paraxial region; an eighth lens element with positive refractive power having a convex object-side surface at a paraxial region; a ninth lens element with negative refractive power having a concave image-side surface at a paraxial region; the method meets the following conditions: TTL/ImgH is less than or equal to 1.35 and less than or equal to 1.41; TTL is the total optical length and ImgH is the half image height. The optical system can achieve both high imaging performance and a compact design.

Description

Optical system, image capturing module and electronic equipment

Technical Field

The present invention relates to the field of image capturing, and in particular, to an optical system, an image capturing module, and an electronic device.

Background

With the updating of technology, consumers have increasingly higher requirements on shooting quality of electronic devices such as smart phones, tablet computers, electronic readers and the like. Generally, a nine-lens type imaging lens has obvious advantages, and can obtain higher resolution, so that the imaging lens is often used in high-end electronic equipment to improve the quality of photographed pictures and resolution and definition.

However, for general electronic devices, the market often desires electronic devices that not only possess excellent image capturing performance, but also that have a reduced thickness as much as possible. However, for an imaging lens with a nine-piece structure, due to the large number of lenses, the axial dimension of the optical system of the imaging lens is difficult to shrink, and the optical system of the imaging lens is difficult to meet the requirement of excellent imaging performance and keep a short dimension, so that the requirements of the electronic equipment on high imaging performance and miniaturization design are difficult to be met.

Disclosure of Invention

Accordingly, it is necessary to provide an optical system, an image capturing module, and an electronic device, which are required to solve the problem that the conventional nine-lens type imaging lens is difficult to satisfy the requirements of the electronic device for high imaging performance and miniaturization design.

An optical system, comprising, in order from an object side to an image side along an optical axis:

a first 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 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 refractive power;

a fourth lens element with refractive power;

A fifth lens element with refractive power;

a sixth lens element with refractive power;

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

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

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

and the optical system satisfies the following conditional expression:

1.35≤TTL/ImgH≤1.41；

the TTL is the distance between the object side surface of the first lens element and the imaging surface of the optical system on the optical axis, that is, the total optical length of the optical system, and ImgH is half of the image height corresponding to the maximum field angle of the optical system.

In the optical system, the positive refractive power of the first lens element is matched with the convex surface type of the object side surface of the first lens element, so that the total length of the optical system is reduced, and the miniaturization design is realized. The negative refractive power of the second lens element is beneficial to correcting the aberration generated by the first lens element by matching with the concave surface type of the image side surface of the second lens element. The refractive power of the first lens and the second lens and the matching of the corresponding surface shapes are favorable for realizing deflection on the light rays entering at a large angle, thereby being favorable for expanding the angle of view of the optical system and reducing the sensitivity of the optical system. The refractive power of the eighth lens element and the ninth lens element and the corresponding surface profile thereof are in cooperation, so that light rays can smoothly transition to an imaging surface through the eighth lens element and the ninth lens element, and aberration can be prevented. Through the lens quantity, the refractive power and the surface type design, the light rays entering at a large angle are favorably and gently transited in the optical system, the generation of spherical aberration and astigmatism can be effectively restrained, and the larger imaging image height and the smaller on-axis size are favorably obtained.

When the refractive power and the surface type characteristics are provided and the upper limit of the condition is met, the optical system can have a large image surface characteristic, so that the optical system can be matched with a photosensitive element with a higher pixel to have better imaging quality, in addition, the axial dimension of the optical system can be prevented from being too long, and further, the requirements of the electronic equipment on high imaging performance and miniaturization design are met. When the lower limit of the conditional expression is met, the optical total length of the optical system can be prevented from being too short relative to the imaging height, so that the incident light rays have enough space deflection when passing through each lens to realize smooth transition, the sensitivity of imaging definition to the optical total length of the system is reduced, the stability of imaging quality is maintained, and the design difficulty of the optical system is reduced. The optical system with the design can meet the requirements of high shooting performance and miniaturization design, and is beneficial to reducing the sensitivity and design difficulty of the optical system.

In one embodiment, the optical system satisfies the following conditional expression:

1.4≤f/EPD≤1.8；

where f is the effective focal length of the optical system and EPD is the entrance pupil diameter of the optical system. The upper limit of the conditional expression is satisfied, so that the optical system has larger aperture and higher light flux, and further, the optical system can have good imaging quality in a low-light environment. The lower limit of the conditional expression is satisfied, the light entering quantity of the optical system is not overlarge, and the generation of the marginal field aberration is favorably limited. Therefore, when the above conditional expression is satisfied, the optical system can realize a large aperture characteristic, and has good imaging quality in a low-light environment.

-6≤f2/f123≤-2.5；

wherein f2 is an effective focal length of the second lens, and f123 is a combined focal length of the first lens, the second lens, and the third lens. When the conditional expression is satisfied, the refractive power of the second lens in the front three lenses is reasonably configured, so that the gentle transition of incident light in the front three lenses of the optical system is facilitated, the deflection angle of marginal view field light is facilitated to be slowed down, the burden of deflecting light of each lens of the third lens image side is reduced, the sensitivity of the optical system is further facilitated to be reduced, and meanwhile, the generation of aberration of the front three lenses is also facilitated to be restrained, so that the imaging quality is facilitated to be improved; in addition, the negative refractive power contribution amount of the second lens is reasonably configured, so that the total length of the system is reduced, the miniaturized design is realized, meanwhile, the surface shape of the second lens is not excessively bent, the processability of the second lens can be improved, and the molding difficulty of the second lens is reduced.

1≤f45/f67≤9；

wherein f45 is a combined focal length of the fourth lens and the fifth lens, and f67 is a combined focal length of the sixth lens and the seventh lens. When the above conditional expressions are satisfied, the ratio of the combined focal lengths of the fourth lens and the fifth lens to the combined focal length of the sixth lens and the seventh lens can be reasonably configured, so that the fourth lens and the fifth lens can effectively balance the aberration generated by the object space and the image space, which is beneficial to balancing the aberration between the fourth lens and the fifth lens and between the sixth lens and the seventh lens, and is beneficial to improving the field curvature and the distortion of the optical system and improving the imaging quality of the optical system. When f45/f67 > 9, the total refractive power provided by the fourth lens element and the fifth lens element is too small to balance the aberrations generated by the front and rear lens elements, resulting in reduced imaging quality; when f45/f67 is smaller than 1, the fourth lens element and the fifth lens element provide excessive negative refractive power, which tends to increase the sensitivity of the optical system, and is disadvantageous for achieving miniaturization and large aperture characteristic of the system.

1≤f89/f≤7.5；

wherein f89 is a combined focal length of the eighth lens and the ninth lens, and f is an effective focal length of the optical system. When the above conditional expression is satisfied, the refractive power contribution of the eighth lens and the ninth lens can be reasonably distributed, which is favorable for reasonably transferring incident light to an imaging surface between the eighth lens and the ninth lens, thereby being favorable for reducing the deflection angle of the light in the optical system, reducing the sensitivity of the optical system and further being favorable for improving the imaging quality of the optical system. When f89/f is more than 7.5, the refractive power provided by the eighth lens and the ninth lens is too small, so that the deflection of the marginal view field rays is not facilitated, the marginal view field is easy to generate serious stray light, the risk of ghost image generation is increased, and the imaging quality is reduced; when f89/f is less than 1, the eighth lens and the ninth lens provide too strong refractive power, which is unfavorable for smooth transition of light rays, and easily increases sensitivity of an optical system and reduces imaging quality of an optical head system.

0.55≤ACT/TTL≤0.65；

wherein ACT is the sum of thicknesses of the lenses in the optical system on the optical axis. When the conditional expression is satisfied, the ratio of the sum of the center thicknesses of the lenses to the total optical length of the system can be reasonably configured, so that the air gaps between the adjacent lenses are facilitated, the assembly difficulty of the optical system is reduced, the assembly stability is improved, and the sensitivity of the optical system is also facilitated to be reduced, and the imaging stability and the imaging quality of the optical system are improved; in addition, the system overall length is also facilitated to be shortened, and the miniaturization design is realized.

-18.3≤(SAG81-SAG72)/ET78≤0.7；

the SAG81 is a distance from an intersection point of the object side surface of the eighth lens element and the optical axis to the maximum effective aperture of the object side surface of the eighth lens element in the optical axis direction, wherein when the maximum effective aperture point of the object side surface of the eighth lens element is located at an image side of an intersection point of the object side surface of the seventh lens element and the optical axis, SAG81 is a positive value, when the maximum effective aperture point of the object side surface of the eighth lens element is located at an object side of an intersection point of the object side surface of the eighth lens element and the optical axis, SAG81 is a negative value, SAG72 is a distance from an image side surface of the seventh lens element to the maximum effective aperture point of the optical axis, that is, a distance from the image side surface of the seventh lens element to the maximum effective aperture point of the seventh lens element in the optical axis direction, SAG72 is a positive value, and SAG72 is a distance from the image side surface of the seventh lens element to the maximum effective aperture point of the image side surface of the seventh lens element in the optical axis. When the conditional expression is satisfied, the sagittal height and the air interval of the image side surface of the seventh lens and the object side surface of the eighth lens can be reasonably configured, and the effective deflection of light on the seventh lens and the eighth lens is facilitated, so that the angle of principal ray on the imaging surface of the optical system is reduced, the relative brightness of the optical system can be effectively improved, and the imaging definition is improved.

1.3≤SD62/SD41≤1.6；

the SD62 is half of the maximum effective aperture of the image side surface of the sixth lens element, and the SD41 is half of the maximum effective aperture of the object side surface of the fourth lens element. When the above conditional expression is satisfied, the ratio of the maximum effective half caliber of the image side surface of the sixth lens to the maximum effective half caliber of the object side surface of the fourth lens can be reasonably configured, which is favorable for reducing the on-axis size of the front lens group, thereby being favorable for the miniaturization design of the optical system, simultaneously being favorable for the optical system to have large image surface characteristics, being capable of matching with the photosensitive element with higher pixel and improving the resolution of the system. When SD62/SD41 is larger than 1.6, the effective aperture steps of the fourth lens to the sixth lens are too large, which is not beneficial to obtaining smaller deflection angle of marginal rays, and meanwhile, the assembly stability of the optical system is reduced.

2.8≤(SD92-SD22)/|SAG92|≤3.8；

the SD92 is half of the maximum effective aperture of the image side surface of the ninth lens, the SD22 is half of the maximum effective aperture of the image side surface of the second lens, and the SAG92 is the sagittal height of the image side surface of the ninth lens at the maximum effective aperture, i.e. the distance from the intersection point of the image side surface of the ninth lens and the optical axis to the maximum effective aperture of the image side surface of the ninth lens in the optical axis direction. When the condition is satisfied, the difference between the maximum effective half calibers of the second lens and the ninth lens and the ratio of the image side sagittal height of the ninth lens can be reasonably configured, so that the effective caliber step difference between the second lens and the ninth lens can be controlled within a reasonable range, the total length of the system can be shortened, and the aperture of the optical system can be increased; in addition, the sagittal height of the image side surface of the ninth lens is reasonably restrained, so that aberration generated by each lens in the object side is corrected by the ninth lens, meanwhile, the image side surface type of the ninth lens cannot be excessively bent, and the machinability of the ninth lens is improved. When (SD 92-SD 22)/|SAG 92| < 2.8, the sagittal height of the image side of the ninth lens is too large, and the image side surface of the ninth lens is too curved, which is not beneficial to the molding processing of the ninth lens; when (SD 92-SD 22)/|SAG 92| > 3.8, the sagittal height of the image side surface of the ninth lens is too small, so that the aberration correction effect of the ninth lens on each lens on the object side is insufficient, and good imaging quality cannot be ensured.

An image capturing module includes a photosensitive element and the optical system according to any of the above embodiments, where the photosensitive element is disposed on an image side of the optical system. The optical system is adopted in the image capturing module, so that the requirements of high image capturing performance and miniaturization design can be met.

An electronic device comprises a shell and the image capturing module, wherein the image capturing module is arranged on the shell. The electronic equipment adopts the image capturing module, so that the requirements of high image capturing performance and miniaturization design can be met.

Drawings

Fig. 1 is a schematic structural view of an optical system in a first embodiment of the present application;

FIG. 2 is a longitudinal spherical aberration, astigmatism and distortion chart of an optical system according to a first embodiment of the present application;

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

FIG. 4 is a longitudinal spherical aberration, astigmatism and distortion chart of an optical system according to a second embodiment of the present application;

fig. 5 is a schematic structural view of an optical system in a third embodiment of the present application;

FIG. 6 is a longitudinal spherical aberration, astigmatism and distortion chart of an optical system according to a third embodiment of the present application;

fig. 7 is a schematic structural view of an optical system in a fourth embodiment of the present application;

FIG. 8 is a longitudinal spherical aberration, astigmatism and distortion chart of an optical system according to a fourth embodiment of the present application;

fig. 9 is a schematic structural view of an optical system in a fifth embodiment of the present application;

FIG. 10 is a longitudinal spherical aberration, astigmatism and distortion chart of an optical system according to a fifth embodiment of the present application;

fig. 11 is a schematic structural view of an optical system in a sixth embodiment of the present application;

FIG. 12 is a longitudinal spherical aberration diagram, an astigmatic diagram, and a distortion diagram of an optical system according to a sixth embodiment of the present application;

fig. 13 is a schematic structural view of an optical system in a seventh embodiment of the present application;

FIG. 14 is a longitudinal spherical aberration, astigmatism and distortion chart of an optical system according to a seventh embodiment of the present application;

fig. 15 is a schematic structural view of an optical system in an eighth embodiment of the present application;

FIG. 16 is a longitudinal spherical aberration, astigmatism and distortion chart of an optical system according to an eighth embodiment of the present application;

FIG. 17 is a schematic diagram of an image capturing module according to an embodiment of the present application;

fig. 18 is a schematic diagram of an electronic device according to an embodiment of the application.

Detailed Description

In order that the above objects, features and advantages of the application will be readily understood, a more particular description of the application will be rendered by reference to the appended drawings. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. The present application may be embodied in many other forms than described herein and similarly modified by those skilled in the art without departing from the spirit of the application, whereby the application is not limited to the specific embodiments disclosed below.

In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. indicate orientations or positional relationships based on the orientations or positional relationships shown in the drawings are merely for convenience in describing the present invention and simplifying the description, and do not indicate or imply that the device or element being referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present invention.

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 at least one such feature. In the description of the present invention, the meaning of "plurality" means at least two, for example, two, three, etc., unless specifically 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; can be mechanically or electrically connected; either directly or indirectly, through intermediaries, or both, may be in communication with each other or in interaction with each other, unless expressly defined otherwise. 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 present invention, unless expressly stated or limited otherwise, a first feature "up" or "down" a second feature may be the first and second features in direct contact, or the first and second features in indirect contact via an intervening medium. Moreover, a first feature being "above," "over" and "on" a second feature may be a first feature being directly above or obliquely above the second feature, or simply indicating that the first feature is level higher than the second feature. The first feature being "under", "below" and "beneath" the second feature may be the first feature being directly under or obliquely below the second feature, or simply indicating that the first feature is less level than the second feature.

It will be understood that when an element is referred to as being "fixed" or "disposed" on another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like are used herein for illustrative purposes only and are not meant to be the only embodiment.

Referring to fig. 1, in some embodiments of the present application, the optical system 100 includes, in order from an object side to an image side along an optical axis 110, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, an eighth lens L8, and a ninth lens L9. Specifically, the first lens element L1 comprises an object-side surface S1 and an image-side surface S2, the second lens element L2 comprises an object-side surface S3 and an image-side surface S4, the third lens element L3 comprises an object-side surface S5 and an image-side surface S6, the fourth lens element L4 comprises an object-side surface S7 and an image-side surface S8, the fifth lens element L5 comprises an object-side surface S9 and an image-side surface S10, the sixth lens element L6 comprises an object-side surface S11 and an image-side surface S12, the seventh lens element L7 comprises an object-side surface S13 and an image-side surface S14, the eighth lens element L8 comprises an object-side surface S15 and an image-side surface S16, and the ninth lens element L9 comprises an object-side surface S17 and an image-side surface S18. 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 coaxially disposed, and an axis common to the lenses in the optical system 100 is an optical axis 110 of the optical system 100.

The first lens element L1 with positive refractive power has a convex object-side surface S1 at the paraxial region 110, which is beneficial to shortening the overall length of the optical system 100 and achieving a compact design. The image-side surface S2 of the first lens element L1 is concave at the paraxial region 110. The second lens element L2 with negative refractive power has a concave image-side surface S4 at a paraxial region 110 of the second lens element S2 for correcting aberrations generated by the first lens element L1. The object side surface S3 of the second lens element L2 is convex at the paraxial region 110. The refractive power of the first lens element L1 and the second lens element L2, and the matching of the respective surface patterns thereof, are beneficial to deflecting the incident light beam with a large angle, thereby being beneficial to expanding the angle of view of the optical system 100 and reducing the sensitivity of the optical system 100. The third lens element L3, the fourth lens element L4, the fifth lens element L5, the sixth lens element L6 and the seventh lens element L7 each have refractive power. The image-side surface S14 of the seventh lens element L7 is concave at the paraxial region 110. The eighth lens element L8 with positive refractive power has a convex object-side surface S15 at a paraxial region 110. The ninth lens element L9 with negative refractive power has a concave image-side surface S18 at a paraxial region 110.

In some embodiments, at least one of the object-side surface S17 and the image-side surface S18 of the ninth lens element L9 has an inflection point, which is disposed to make the refractive power configuration of the ninth lens element L9 in the vertical axis direction more uniform, thereby correcting the aberration of the off-axis field of view.

In addition, in some embodiments, the optical system 100 is provided with a stop STO, which may be disposed on the object side of the first lens L1. Further, the optical system 100 further includes an image plane S21 located at the image side of the ninth lens L9, where the image plane S21 is an imaging plane of the optical system 100, and the incident light can be imaged on the image plane S21 after being adjusted by 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. In some embodiments, the optical system 100 further includes an infrared cut filter L10 disposed on the image side of the ninth lens L9, where the infrared cut filter L10 is used to filter out the interference light, and prevent the interference light from reaching the image surface S21 of the optical system 100 to affect normal imaging.

In some embodiments, the object side and the image side of each lens of the optical system 100 are both aspheric. The adoption of the aspheric structure can improve the flexibility of lens design, effectively correct spherical aberration and improve imaging quality. In other embodiments, the object side and image side of each lens of the optical system 100 may be spherical. It should be noted that the above embodiments are merely examples of some embodiments of the present application, and in some embodiments, the surfaces of the lenses in the optical system 100 may be aspherical or any combination of spherical surfaces.

In some embodiments, the materials of the lenses in the optical system 100 may be glass or plastic. The plastic lens can reduce the weight of the optical system 100 and the production cost, and the small size of the optical system 100 is matched to realize the light and thin design of the optical system 100. The lens made of glass material provides the optical system 100 with excellent optical performance and high temperature resistance. It should be noted that the materials of the lenses in the optical system 100 may be any combination of glass and plastic, and are not necessarily all glass or all plastic.

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.

Further, in some embodiments, the optical system 100 satisfies the conditional expression: TTL/ImgH is less than or equal to 1.35 and less than or equal to 1.41; wherein TTL is a distance from the object side surface S1 of the first lens element L1 to the imaging surface of the optical system 100 on the optical axis 110, and ImgH is half of an image height corresponding to a maximum field angle of the optical system 100. Specifically, TTL/ImgH may be: 1.364, 1.371, 1.382, 1.385, 1.390, 1.391, 1.395, 1.399, 1.401, or 1.402. The optical system 100 can have a large image plane characteristic when the upper limit of the conditional expression is satisfied, so that the optical system 100 can be matched with a photosensitive element with a higher pixel to have better imaging quality, and in addition, the axial dimension of the optical system 100 can be prevented from being too long, so that the requirements of electronic equipment on high imaging performance and miniaturization design are met. When the lower limit of the above conditional expression is satisfied, the optical total length of the optical system 100 can be prevented from being too short relative to the imaging image height, so that the incident light rays have enough space deflection when passing through each lens to realize smooth transition, and the sensitivity of the imaging definition to the optical total length of the system is reduced, thereby maintaining the stability of the imaging quality, and being beneficial to reducing the design difficulty of the optical system 100. The optical system 100 with the design can meet the requirements of high imaging performance and miniaturization design, and is beneficial to reducing the sensitivity and design difficulty of the optical system 100.

It should be noted that, in some embodiments, the optical system 100 may match a photosensitive element having a rectangular photosensitive surface, and the imaging surface of the optical system 100 coincides with the photosensitive surface of the photosensitive element. At this time, if the effective pixel area on the imaging plane of the optical system 100 has the horizontal direction and the diagonal direction, the maximum field angle FOV of the optical system 100 may be understood as the maximum field angle of the diagonal direction of the optical system 100, and ImgH may be understood as half the length of the effective pixel area on the imaging plane of the optical system 100 in the diagonal direction.

In some embodiments, the optical system 100 satisfies the conditional expression: f/EPD is not less than 1.4 and not more than 1.8; where f is the effective focal length of the optical system 100 and EPD is the entrance pupil diameter of the optical system 100. Specifically, the f/EPD may be: 1.482, 1.510, 1.533, 1.628, 1.632, 1.688, 1.703, 1.725, 1.765, or 1.800. The upper limit of the above conditional expression is satisfied, which is favorable for making the optical system 100 have a larger aperture and a higher light flux, and further making the optical system 100 have good imaging quality in a low light environment. The lower limit of the above conditional expression is satisfied, and the light entering amount of the optical system 100 is not excessively large, which is advantageous for limiting the occurrence of the fringe field aberration. Therefore, when the above conditional expression is satisfied, the optical system 100 can realize a large aperture characteristic and has good imaging quality in a low-light environment.

In some embodiments, the optical system 100 satisfies the conditional expression: -6 is less than or equal to f2/f123 is less than or equal to-2.5; wherein f2 is the effective focal length of the second lens L2, and f123 is the combined focal length of the first lens L1, the second lens L2, and the third lens L3. Specifically, f2/f123 may be: -5.900, -5.822, -5.112, -4.356, -4.212, -3.987, -3.555, -2.778, -2.612, or-2.563. When the above conditional expression is satisfied, the refractive power of the second lens L2 in the first three lenses is reasonably configured, which is favorable for smooth transition of the incident light in the first three lenses of the optical system 100, thereby being favorable for slowing down the deflection angle of the marginal view field light, reducing the burden of deflecting the light by each lens in the image side of the third lens L3, further being favorable for reducing the sensitivity of the optical system 100, and also favorable for inhibiting the generation of aberration of the first three lenses, thereby being favorable for improving the imaging quality; in addition, the reasonable configuration of the negative refractive power contribution of the second lens L2 is beneficial to shortening the total length of the system and realizing miniaturization design, meanwhile, the surface shape of the second lens L2 cannot be excessively bent, the processability of the second lens L2 can be improved, and the molding difficulty of the second lens L2 is reduced.

In some embodiments, the optical system 100 satisfies the conditional expression: f45/f67 is more than or equal to 1 and less than or equal to 9; wherein f45 is a combined focal length of the fourth lens L4 and the fifth lens L5, and f67 is a combined focal length of the sixth lens L6 and the seventh lens L7. Specifically, f45/f67 may be: 1.224, 1.556, 1.842, 2.111, 2.124, 2.653, 3.451, 4.300, 4.414, or 8.67. When the above conditional expressions are satisfied, the ratio of the combined focal lengths of the fourth lens element L4 and the fifth lens element L5 to the combined focal length of the sixth lens element L6 and the seventh lens element L7 can be reasonably configured, so that the aberrations generated by the object side and the image side lens can be effectively balanced by the fourth lens element L4 and the fifth lens element L5, and the aberrations between the fourth lens element L4 and the fifth lens element L5 and the aberrations between the sixth lens element L6 and the seventh lens element L7 can be balanced, thereby improving the curvature of field and the distortion of the optical system 100, and improving the imaging quality of the optical system 100. When f45/f67 > 9, the total refractive power provided by the fourth lens element L4 and the fifth lens element L5 is too small to balance the aberrations generated by the front and rear lens elements, resulting in reduced imaging quality; when f45/f67 is smaller than 1, the negative refractive powers provided by the fourth lens element L4 and the fifth lens element L5 are too high, which may easily result in increased sensitivity of the optical system 100, and are disadvantageous in achieving miniaturization and large aperture characteristics of the system.

In some embodiments, the optical system 100 satisfies the conditional expression: f89/f is more than or equal to 1 and less than or equal to 7.5; where f89 is a combined focal length of the eighth lens L8 and the ninth lens L9, and f is an effective focal length of the optical system 100. Specifically, f89/f may be: 1.311, 1.355, 1.377, 1.421, 1.455, 1.497, 1.502, 1.521, 1.566, or 7.271. When the above conditional expression is satisfied, the refractive power contributions of the eighth lens element L8 and the ninth lens element L9 can be reasonably distributed, which is favorable for reasonably transferring the incident light beam between the eighth lens element L8 and the ninth lens element L9 to the imaging surface, thereby being favorable for reducing the deflection angle of the light beam in the optical system 100, reducing the sensitivity of the optical system 100, and further being favorable for improving the imaging quality of the optical system 100. When f89/f is more than 7.5, the refractive power provided by the eighth lens element L8 and the ninth lens element L9 is too small, which is not beneficial to deflection of light rays of the edge view field, so that serious stray light phenomenon of the edge view field is easy to occur, the risk of ghost image generation is increased, and the imaging quality is reduced; when f89/f < 1, the refractive powers provided by the eighth lens element L8 and the ninth lens element L9 are too strong, which is not beneficial to smooth transition of light rays, and the sensitivity of the optical system 100 is easily increased, and the imaging quality of the optical system 100 is reduced.

In some embodiments, the optical system 100 satisfies the conditional expression: ACT/TTL is more than or equal to 0.55 and less than or equal to 0.65; where ACT is the sum of the thicknesses of the lenses in the optical system 100 on the optical axis 110. Specifically, ACT/TTL may be: 0.596, 0.598, 0.601, 0.603, 0.608, 0.614, 0.617, 0.619, 0.621 or 0.624. When the above conditional expression is satisfied, the ratio of the sum of the center thicknesses of the lenses to the total optical length of the system can be reasonably configured, which is favorable for providing enough air gaps between adjacent lenses, thereby being favorable for reducing the assembly difficulty of the optical system 100, improving the assembly stability, and simultaneously being favorable for reducing the sensitivity of the optical system 100, thereby improving the imaging stability and the imaging quality of the optical system 100; in addition, the system overall length is also facilitated to be shortened, and the miniaturization design is realized.

In some embodiments, the optical system 100 satisfies the conditional expression: -18.3.ltoreq.SAG 81-SAG 72)/ET 78.ltoreq.0.7; wherein SAG81 is the sagittal height of the object side S15 of the eighth lens element L8 at the maximum effective aperture, SAG72 is the sagittal height of the image side S14 of the seventh lens element L7 at the maximum effective aperture, and ET78 is the distance from the maximum effective aperture of the image side S14 of the seventh lens element L7 to the object side S15 of the eighth lens element L8 in the direction of the optical axis 110. Specifically, (SAG 81-SAG 72)/ET 78 may be: -18.201, -1.995, -1.521, -1.112, 0.001, 0.335, 0.457, 0.512, 0.594 or 0.644. When the above conditional expressions are satisfied, the sagittal height and the air interval of the image side surface S14 of the seventh lens element L7 and the object side surface S15 of the eighth lens element S8 can be reasonably configured, which is favorable for effectively deflecting light rays at the seventh lens element L7 and the eighth lens element L8, thereby being favorable for reducing the chief ray angle on the imaging surface of the optical system 100, and further effectively improving the relative brightness of the optical system 100 and the imaging definition.

In some embodiments, the optical system 100 satisfies the conditional expression: SD62/SD41 is more than or equal to 1.3 and less than or equal to 1.6; the image side surface S12 of the sixth lens element L6 has a half maximum effective aperture, and the object side surface S7 of the fourth lens element L4 has a half maximum effective aperture, SD 41. Specifically, SD62/SD41 may be: 1.393, 1.401, 1.425, 1.453, 1.460, 1.477, 1.489, 1.501, 1.510, or 1.513. When the above conditional expression is satisfied, the ratio of the maximum effective half-caliber of the image side surface S12 of the sixth lens element L6 to the maximum effective half-caliber of the object side surface S7 of the fourth lens element L4 can be reasonably configured, which is favorable for reducing the on-axis size of the front lens group, thereby being favorable for the miniaturization design of the optical system 100, being favorable for the optical system 100 to have a large image surface characteristic, being capable of matching with the photosensitive element with higher pixel and improving the resolution of the system. When SD62/SD41 is greater than 1.6, the effective aperture steps of the fourth lens L4 to the sixth lens L6 are too large, which is unfavorable for obtaining smaller deflection angle of marginal rays and reduces the assembly stability of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: 2.8 < (SD 92-SD 22)/|SAG 92| < 3.8; the SD92 is half of the maximum effective aperture of the image side surface S18 of the ninth lens element L9, the SD22 is half of the maximum effective aperture of the image side surface S4 of the second lens element L2, and the SAG92 is the sagittal height of the image side surface S18 of the ninth lens element L9 at the maximum effective aperture. Specifically, (SD 92-SD 22)/|sag92| may be: 2.856, 2.915, 3.022, 3.147, 3.268, 3.355, 3.474, 3.552, 3.632 or 3.749. When the above conditional expression is satisfied, the difference between the maximum effective half calibers of the second lens element L2 and the ninth lens element L9 and the ratio of the sagittal height of the image side S18 of the ninth lens element L9 can be reasonably configured, which is beneficial to controlling the effective caliber step of the second lens element L2 to the effective caliber step of the ninth lens element L18 within a reasonable range, thereby being beneficial to shortening the total length of the system and increasing the aperture of the optical system 100; in addition, the sagittal height of the image side surface S18 of the ninth lens element L9 is advantageously restricted, so that the aberration generated by each lens element in the object side can be corrected by the ninth lens element L9, and meanwhile, the image side surface S18 of the ninth lens element L9 is not excessively curved, so that the workability of the ninth lens element L9 is improved. When (SD 92-SD 22)/|SAG 92| < 2.8, the sagittal height of the image side S18 of the ninth lens L9 is too large, and the image side S18 of the ninth lens L9 is too curved, which is unfavorable for the molding processing of the ninth lens L9; when (SD 92-SD 22)/|sag 92| > 3.8, the sagittal height of the image side surface S18 of the ninth lens element L9 is too small, resulting in insufficient aberration correction effect of the ninth lens element L9 on each lens element on the object side, and good imaging quality cannot be ensured.

The reference wavelengths for the above effective focal length and combined focal length values are 555nm.

From the above description of the embodiments, more particular embodiments and figures are set forth below in detail.

First embodiment

Referring to fig. 1 and 2, fig. 1 is a schematic structural diagram of an optical system 100 in a first embodiment, wherein the optical system 100 includes, in order from an object side to an image side, a stop STO, a first lens L1 with positive refractive power, a second lens L2 with negative refractive power, a third lens L3 with positive refractive power, a fourth lens L4 with negative refractive power, a fifth lens L5 with positive refractive power, a sixth lens L6 with negative refractive power, a seventh lens L7 with negative refractive power, an eighth lens L8 with positive refractive power, and a ninth lens L9 with negative refractive power. Fig. 2 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the first embodiment, from left to right, where the reference wavelength of the astigmatism graph and the distortion graph is 555nm, and other embodiments are the same.

The object side surface S1 of the first lens element L1 is convex at a paraxial region 110 and concave at a peripheral region;

the image-side surface S2 of the first lens element L1 is concave at a paraxial region 110 and convex at a peripheral region;

The object side surface S3 of the second lens element L2 is convex at the paraxial region 110 and convex at the peripheral region;

the image-side surface S4 of the second lens element L2 is concave at the paraxial region 110 and concave at the peripheral region;

the object side surface S5 of the third lens element L3 is convex at a paraxial region 110 and concave at a peripheral region;

the image-side surface S6 of the third lens element L3 is convex at the paraxial region 110 and convex at the peripheral region;

the fourth lens element L4 has a concave object-side surface S7 at a paraxial region 110 and a convex object-side surface S7 at a peripheral region;

the image-side surface S8 of the fourth lens element L4 is concave at the paraxial region 110 and concave at the peripheral region;

the object side surface S9 of the fifth lens element L5 is convex at the paraxial region 110 and convex at the circumferential region;

the image-side surface S10 of the fifth lens element L5 is convex at a paraxial region 110 and concave at a peripheral region;

the object side surface S11 of the sixth lens element L6 is concave at the paraxial region 110 and convex at the peripheral region;

the image-side surface S12 of the sixth lens element L6 is convex at the paraxial region 110 and convex at the peripheral region;

the object side surface S13 of the seventh lens element L7 is convex at the paraxial region 110 and convex at the peripheral region;

the image-side surface S14 of the seventh lens element L7 is concave at the paraxial region 110 and concave at the peripheral region;

the object side surface S15 of the eighth lens element L8 is convex at the paraxial region 110 and concave at the peripheral region;

The image-side surface S16 of the eighth lens element L8 is concave at the paraxial region 110 and concave at the peripheral region;

the object side surface S17 of the ninth lens element L9 is concave at the paraxial region 110 and concave at the peripheral region;

the image-side surface S18 of the ninth lens element L9 is concave at the paraxial region 110 and convex at the peripheral region.

The object side surfaces and the image side surfaces of 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 aspheric.

It should be noted that in the present application, when one surface of the lens is described as being convex at the paraxial region 110 (the central region of the surface), it is understood that the region of the surface of the lens near the optical axis 110 is convex. When describing a surface of a lens as concave at the circumference, it is understood that the surface is concave in the area near the maximum effective radius. For example, when the surface is convex at the paraxial region 110 and also convex at the circumference, the shape of the surface from the center (the intersection of the surface and the optical axis 110) to the edge direction may be purely convex; or first transition from a convex shape in the center to a concave shape and then become convex near the maximum effective radius. The various shape structures (concave-convex relationship) of the surface are not fully revealed here only for the purpose of explaining the relationship at the optical axis 110 with the circumference, but other cases may be deduced from the above examples.

The materials 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 all plastics.

Further, the optical system 100 satisfies the conditional expression: TTL/imgh=1.390; wherein TTL is a distance from the object side surface S1 of the first lens element L1 to the imaging surface of the optical system 100 on the optical axis 110, and ImgH is half of an image height corresponding to a maximum field angle of the optical system 100. When the above conditional expression is satisfied, the requirements of high imaging performance and miniaturization design can be satisfied, and the sensitivity and design difficulty of the optical system 100 can be reduced.

The optical system 100 satisfies the conditional expression: f/epd=1.576; where f is the effective focal length of the optical system 100 and EPD is the entrance pupil diameter of the optical system 100. Therefore, when the above conditional expression is satisfied, the optical system 100 can realize a large aperture characteristic, has good imaging quality in a low-light environment, and is also beneficial to suppressing the generation of field aberration at the edge of the optical system 100.

The optical system 100 satisfies the conditional expression: f2/f123= -4.002; wherein f2 is the effective focal length of the second lens L2, and f123 is the combined focal length of the first lens L1, the second lens L2, and the third lens L3. When the above conditional expression is satisfied, the refractive power of the second lens L2 in the first three lenses is reasonably configured, which is favorable for smooth transition of the incident light in the first three lenses of the optical system 100, thereby being favorable for slowing down the deflection angle of the marginal view field light, reducing the burden of deflecting the light by each lens in the image side of the third lens L3, further being favorable for reducing the sensitivity of the optical system 100, and also favorable for inhibiting the generation of aberration of the first three lenses, thereby being favorable for improving the imaging quality; in addition, the reasonable configuration of the negative refractive power contribution of the second lens L2 is beneficial to shortening the total length of the system and realizing miniaturization design, meanwhile, the surface shape of the second lens L2 cannot be excessively bent, the processability of the second lens L2 can be improved, and the molding difficulty of the second lens L2 is reduced.

The optical system 100 satisfies the conditional expression: f45/f67=2.918; wherein f45 is a combined focal length of the fourth lens L4 and the fifth lens L5, and f67 is a combined focal length of the sixth lens L6 and the seventh lens L7. When the above conditional expressions are satisfied, the ratio of the combined focal lengths of the fourth lens element L4 and the fifth lens element L5 to the combined focal length of the sixth lens element L6 and the seventh lens element L7 can be reasonably configured, so that the aberrations generated by the object side and the image side lens can be effectively balanced by the fourth lens element L4 and the fifth lens element L5, and the aberrations between the fourth lens element L4 and the fifth lens element L5 and the aberrations between the sixth lens element L6 and the seventh lens element L7 can be balanced, thereby improving the curvature of field and the distortion of the optical system 100, and improving the imaging quality of the optical system 100. When f45/f67 > 9, the total refractive power provided by the fourth lens element L4 and the fifth lens element L5 is too small to balance the aberrations generated by the front and rear lens elements, resulting in reduced imaging quality; when f45/f67 is smaller than 1, the negative refractive powers provided by the fourth lens element L4 and the fifth lens element L5 are too high, which may easily result in increased sensitivity of the optical system 100, and are disadvantageous in achieving miniaturization and large aperture characteristics of the system.

The optical system 100 satisfies the conditional expression: f89/f=1.676; where f89 is a combined focal length of the eighth lens L8 and the ninth lens L9, and f is an effective focal length of the optical system 100. When the above conditional expression is satisfied, the refractive power contributions of the eighth lens element L8 and the ninth lens element L9 can be reasonably distributed, which is favorable for reasonably transferring the incident light beam between the eighth lens element L8 and the ninth lens element L9 to the imaging surface, thereby being favorable for reducing the deflection angle of the light beam in the optical system 100, reducing the sensitivity of the optical system 100, and further being favorable for improving the imaging quality of the optical system 100. When f89/f is more than 7.5, the refractive power provided by the eighth lens element L8 and the ninth lens element L9 is too small, which is not beneficial to deflection of light rays of the edge view field, so that serious stray light phenomenon of the edge view field is easy to occur, the risk of ghost image generation is increased, and the imaging quality is reduced; when f89/f < 1, the refractive powers provided by the eighth lens element L8 and the ninth lens element L9 are too strong, which is not beneficial to smooth transition of light rays, and the sensitivity of the optical system 100 is easily increased, and the imaging quality of the optical system 100 is reduced.

The optical system 100 satisfies the conditional expression: ACT/ttl=0.614; where ACT is the sum of the thicknesses of the lenses in the optical system 100 on the optical axis 110. When the above conditional expression is satisfied, the ratio of the sum of the center thicknesses of the lenses to the total optical length of the system can be reasonably configured, which is favorable for providing enough air gaps between adjacent lenses, thereby being favorable for reducing the assembly difficulty of the optical system 100, improving the assembly stability, and simultaneously being favorable for reducing the sensitivity of the optical system 100, thereby improving the imaging stability and the imaging quality of the optical system 100; in addition, the system overall length is also facilitated to be shortened, and the miniaturization design is realized.

The optical system 100 satisfies the conditional expression: (SAG 81-SAG 72)/et78=0.351; wherein SAG81 is the sagittal height of the object side S15 of the eighth lens element L8 at the maximum effective aperture, SAG72 is the sagittal height of the image side S14 of the seventh lens element L7 at the maximum effective aperture, and ET78 is the distance from the maximum effective aperture of the image side S14 of the seventh lens element L7 to the object side S15 of the eighth lens element L8 in the direction of the optical axis 110. When the above conditional expressions are satisfied, the sagittal height and the air interval of the image side surface S14 of the seventh lens element L7 and the object side surface S15 of the eighth lens element S8 can be reasonably configured, which is favorable for effectively deflecting light rays at the seventh lens element L7 and the eighth lens element L8, thereby being favorable for reducing the chief ray angle on the imaging surface of the optical system 100, and further effectively improving the relative brightness of the optical system 100 and the imaging definition.

The optical system 100 satisfies the conditional expression: SD62/SD41 = 1.393; the image side surface S12 of the sixth lens element L6 has a half maximum effective aperture, and the object side surface S7 of the fourth lens element L4 has a half maximum effective aperture, SD 41. When the above conditional expression is satisfied, the ratio of the maximum effective half-caliber of the image side surface S12 of the sixth lens element L6 to the maximum effective half-caliber of the object side surface S7 of the fourth lens element L4 can be reasonably configured, which is favorable for reducing the on-axis size of the front lens group, thereby being favorable for the miniaturization design of the optical system 100, being favorable for the optical system 100 to have a large image surface characteristic, being capable of matching with the photosensitive element with higher pixel and improving the resolution of the system. When SD62/SD41 is greater than 1.6, the effective aperture steps of the fourth lens L4 to the sixth lens L6 are too large, which is unfavorable for obtaining smaller deflection angle of marginal rays and reduces the assembly stability of the optical system 100.

The optical system 100 satisfies the conditional expression: (SD 92-SD 22)/|sag 92|= 2.926; the SD92 is half of the maximum effective aperture of the image side surface S18 of the ninth lens element L9, the SD22 is half of the maximum effective aperture of the image side surface S4 of the second lens element L2, and the SAG92 is the sagittal height of the image side surface S18 of the ninth lens element L9 at the maximum effective aperture. When the above conditional expression is satisfied, the difference between the maximum effective half calibers of the second lens element L2 and the ninth lens element L9 and the ratio of the sagittal height of the image side S18 of the ninth lens element L9 can be reasonably configured, which is beneficial to controlling the effective caliber step of the second lens element L2 to the effective caliber step of the ninth lens element L18 within a reasonable range, thereby being beneficial to shortening the total length of the system and increasing the aperture of the optical system 100; in addition, the sagittal height of the image side surface S18 of the ninth lens element L9 is advantageously restricted, so that the aberration generated by each lens element in the object side can be corrected by the ninth lens element L9, and meanwhile, the image side surface S18 of the ninth lens element L9 is not excessively curved, so that the workability of the ninth lens element L9 is improved. When (SD 92-SD 22)/|SAG 92| < 2.8, the sagittal height of the image side S18 of the ninth lens L9 is too large, and the image side S18 of the ninth lens L9 is too curved, which is unfavorable for the molding processing of the ninth lens L9; when (SD 92-SD 22)/|sag 92| > 3.8, the sagittal height of the image side surface S18 of the ninth lens element L9 is too small, resulting in insufficient aberration correction effect of the ninth lens element L9 on each lens element on the object side, and good imaging quality cannot be ensured.

In addition, various parameters of the optical system 100 are given in table 1. The image plane S21 in table 1 can be understood as the imaging plane of the optical system 100. The elements from the object plane (not shown) to the image plane S21 are arranged in the order of the elements from top to bottom in table 1. The radius Y in table 1 is the radius of curvature of the object or image side of the corresponding surface number at the optical axis 110. The surface numbers S1 and S2 are the object side surface S1 and the image side surface S2 of the first lens element L1, respectively, i.e., the surface with the smaller surface number is the object side surface and the surface with the larger surface number is the image side surface in the same lens element. The first value in the "thickness" parameter row of the first lens element L1 is the thickness of the lens element on the optical axis 110, and the second value is the distance from the image side surface of the lens element to the rear surface of the image side direction on the optical axis 110.

Note that in this embodiment and the following embodiments, the optical system 100 may not be provided with the ir cut filter L10, but the distance from the image side surface S18 to the image surface S21 of the ninth lens L9 remains unchanged.

In the first embodiment, the effective focal length f= 6.060mm, the f-number fno=1.576, the maximum field angle fov= 83.098deg, and the optical total length ttl= 7.660mm of the optical system 100. In the first embodiment and the other embodiments, the optical system 100 satisfies the conditional expression: FNO is more than or equal to 1.4 and less than or equal to 1.8;7.641mm is less than or equal to TTL is less than or equal to 7.720mm; imgH is less than or equal to 5.45mm and less than or equal to 5.51mm; the optical system 100 has a large aperture characteristic, and can have good imaging quality even in a low-light environment, the optical system 100 can meet the requirement of miniaturization design, the optical system 100 has a large image plane characteristic, and can be matched with a photosensitive element with high pixel, so that the resolution of the optical system 100 is improved.

The reference wavelength of the focal length of each lens is 555nm, the reference wavelength of the refractive index and Abbe number is 587.56nm (d-line), and other embodiments are the same.

TABLE 1

Further, the aspherical coefficients of the image side or object side of each lens of the optical system 100 are given in table 2. Wherein the plane numbers S1-S18 represent the image side surfaces or the object side surfaces S1-S18, respectively. And K-a20 from top to bottom respectively represent types of aspherical coefficients, where K represents a conic coefficient, A4 represents four times an aspherical coefficient, A6 represents six times an aspherical coefficient, A8 represents eight times an aspherical coefficient, and so on. In addition, the aspherical coefficient formula is as follows:

where Z is the distance from the corresponding point on the aspheric surface to the plane tangential to the surface vertex, r is the distance from the corresponding point on the aspheric surface to the optical axis 110, c is the curvature of the aspheric vertex, k is the conic coefficient, ai is the coefficient corresponding to the i-th higher term in the aspheric surface formula.

TABLE 2

In addition, fig. 2 includes a longitudinal spherical aberration diagram (Longitudinal Spherical Aberration) of the optical system 100, which shows the deviation of the focal point of light rays of 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 plane to the intersection of the light ray with the optical axis 110. As can be seen from the longitudinal spherical aberration diagram, the degree of focus deviation of the light beams with the respective wavelengths in the first embodiment tends to be uniform, and the diffuse spots or the halos in the imaging picture are effectively suppressed. Fig. 2 also includes a field profile (ASTIGMATIC FIELD CURVES) of the optical system 100, wherein the S-curve represents the sagittal field profile at 555nm and the T-curve represents the meridional field profile at 555 nm. As can be seen from the figure, the field curvature of the optical system 100 is small, the field curvature and astigmatism of each field of view are well corrected, and the center and the edge of the field of view have clear imaging. Fig. 2 also includes a DISTORTION map (DISTORTION) of the optical system 100, in which it is seen that the DISTORTION of the image caused by the main beam is small and the imaging quality of the system is good.

Second embodiment

Referring to fig. 3 and 4, fig. 3 is a schematic structural diagram of an optical system 100 in a second embodiment, wherein the optical system 100 sequentially includes, from an object side to an image side, a stop STO, a first lens L1 with positive refractive power, a second lens L2 with negative refractive power, a third lens L3 with positive refractive power, a fourth lens L4 with negative refractive power, a fifth lens L5 with negative refractive power, a sixth lens L6 with negative refractive power, a seventh lens L7 with negative refractive power, an eighth lens L8 with positive refractive power, and a ninth lens L9 with negative refractive power. Fig. 4 is a graph showing longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the second embodiment in order from left to right.

the object side surface S5 of the third lens element L3 is concave at the paraxial region 110 and concave at the peripheral region;

the image-side surface S8 of the fourth lens element L4 is convex at a paraxial region 110 and concave at a peripheral region;

the object side surface S9 of the fifth lens element L5 is concave at the paraxial region 110 and convex at the peripheral region;

the image-side surface S10 of the fifth lens element L5 is concave at the paraxial region 110 and concave at the peripheral region;

the image-side surface S12 of the sixth lens element L6 is convex at the paraxial region 110 and concave at the peripheral region;

the object side surface S13 of the seventh lens element L7 is concave at the paraxial region 110 and convex at the peripheral region;

the image-side surface S16 of the eighth lens element L8 is convex at the paraxial region 110 and concave at the peripheral region;

the object side surface S17 of the ninth lens element L9 is convex at the paraxial region 110 and concave at the peripheral region;

In addition, the parameters of the optical system 100 are given in table 3, and the definition of the parameters can be obtained in the first embodiment, which is not described herein.

TABLE 3 Table 3

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Further, the aspheric coefficients of the image side or the object side of each lens of the optical system 100 are given in table 4, and the definition of each parameter can be obtained from the first embodiment, which is not described herein.

TABLE 4 Table 4

From the above provided parameter information, the following data can be deduced:

TTL/ImgH	1.402	ACT/TTL	0.624
				f/EPD	1.582	(SAG81-SAG72)/ET78	0.644
f2/f123	-4.356	SD62/SD41	1.467
				f45/f67	2.646	(SD92-SD22)/\|SAG92\|	3.043
f89/f	1.666

in addition, as can be seen from the aberration diagram in fig. 4, the longitudinal spherical aberration, curvature of field and distortion of the optical system 100 are all well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Third embodiment

Referring to fig. 5 and 6, fig. 5 is a schematic structural diagram of an optical system 100 in a third embodiment, wherein the optical system 100 sequentially includes, from an object side to an image side, a stop STO, a first lens L1 with positive refractive power, a second lens L2 with negative refractive power, a third lens L3 with positive refractive power, a fourth lens L4 with positive refractive power, a fifth lens L5 with negative refractive power, a sixth lens L6 with positive refractive power, a seventh lens L7 with negative refractive power, an eighth lens L8 with positive refractive power, and a ninth lens L9 with negative refractive power. Fig. 6 is a graph showing longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the third embodiment in order from left to right.

The object side surface S1 of the first lens element L1 is convex at the paraxial region 110 and convex at the peripheral region;

the object side surface S9 of the fifth lens element L5 is concave at the paraxial region 110 and concave at the peripheral region;

the object side surface S11 of the sixth lens element L6 is concave at the paraxial region 110 and concave at the peripheral region;

In addition, the parameters of the optical system 100 are given in table 5, and the definition of the parameters can be obtained in the first embodiment, which is not described herein.

TABLE 5

Further, the aspheric coefficients of the image side or the object side of each lens of the optical system 100 are given in table 6, and the definition of each parameter can be obtained from the first embodiment, which is not described herein.

TABLE 6

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And, according to the above-provided parameter information, the following data can be deduced:

TTL/ImgH	1.390	ACT/TTL	0.606
				f/EPD	1.700	(SAG81-SAG72)/ET78	0.306
f2/f123	-3.349	SD62/SD41	1.476
				f45/f67	2.405	(SD92-SD22)/\|SAG92\|	2.991
f89/f	1.722

in addition, as is clear from the aberration diagram in fig. 6, the longitudinal spherical aberration, curvature of field, and distortion of the optical system 100 are all well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Fourth embodiment

Referring to fig. 7 and 8, fig. 7 is a schematic structural diagram of an optical system 100 in a fourth embodiment, wherein the optical system 100 sequentially includes, from an object side to an image side, a stop STO, a first lens L1 with positive refractive power, a second lens L2 with negative refractive power, a third lens L3 with positive refractive power, a fourth lens L4 with negative refractive power, a fifth lens L5 with negative refractive power, a sixth lens L6 with positive refractive power, a seventh lens L7 with negative refractive power, an eighth lens L8 with positive refractive power, and a ninth lens L9 with negative refractive power. Fig. 8 is a graph showing longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the fourth embodiment in order from left to right.

the object side surface S5 of the third lens element L3 is convex at the paraxial region 110 and convex at the peripheral region;

the object side surface S15 of the eighth lens element L8 is convex at the paraxial region 110 and convex at the circumferential region;

In addition, the parameters of the optical system 100 are given in table 7, and the definition of the parameters can be obtained in the first embodiment, which is not described herein.

TABLE 7

Further, the aspheric coefficients of the image side or the object side of each lens in the optical system 100 are given in table 8, and the definition of each parameter can be obtained from the first embodiment, which is not described herein.

TABLE 8

/>

TTL/ImgH	1.364	ACT/TTL	0.600
				f/EPD	1.800	(SAG81-SAG72)/ET78	-0.687
f2/f123	-5.900	SD62/SD41	1.510
				f45/f67	1.245	(SD92-SD22)/\|SAG92\|	3.749
f89/f	1.617

In addition, as is clear from the aberration diagram in fig. 8, the longitudinal spherical aberration, curvature of field, and distortion of the optical system 100 are all well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Fifth embodiment

Referring to fig. 9 and 10, fig. 9 is a schematic structural diagram of an optical system 100 in a fifth embodiment, wherein the optical system 100 sequentially includes, from an object side to an image side, a stop STO, a first lens L1 with positive refractive power, a second lens L2 with negative refractive power, a third lens L3 with positive refractive power, a fourth lens L4 with negative refractive power, a fifth lens L5 with negative refractive power, a sixth lens L6 with positive refractive power, a seventh lens L7 with negative refractive power, an eighth lens L8 with positive refractive power, and a ninth lens L9 with negative refractive power. Fig. 10 is a graph showing longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the fifth embodiment in order from left to right.

the image-side surface S6 of the third lens element L3 is concave at a paraxial region 110 and convex at a peripheral region;

the object side surface S9 of the fifth lens element L5 is convex at the paraxial region 110 and concave at the peripheral region;

the object side surface S11 of the sixth lens element L6 is convex at the paraxial region 110 and concave at the peripheral region;

the image-side surface S12 of the sixth lens element L6 is concave at the paraxial region 110 and concave at the peripheral region;

In addition, the parameters of the optical system 100 are given in table 9, and the definition of the parameters can be obtained in the first embodiment, which is not described herein.

TABLE 9

Further, the aspheric coefficients of the image side or the object side of each lens of the optical system 100 are given in table 10, and the definition of each parameter can be obtained from the first embodiment, which is not described herein.

Table 10

Face number

S1

S2

S3

S4

S5

S6

K

0.000E+00

A4

1.925E-04

-2.635E-02

-4.256E-02

-2.143E-02

-9.422E-03

-6.279E-03

A6

1.750E-03

1.763E-02

2.272E-02

7.326E-03

-1.960E-03

-2.715E-02

A8

-2.535E-03

-6.569E-03

-2.497E-03

9.950E-03

9.574E-04

4.524E-02

A10

2.544E-03

4.937E-04

-6.753E-03

-1.856E-02

-5.292E-03

-5.751E-02

A12

-1.559E-03

8.321E-04

6.828E-03

1.632E-02

6.062E-03

4.576E-02

A14

5.928E-04

-4.735E-04

-3.543E-03

-8.735E-03

-3.560E-03

-2.268E-02

A16

-1.367E-04

1.192E-04

1.102E-03

2.884E-03

1.067E-03

6.813E-03

A18

1.745E-05

-1.441E-05

-1.910E-04

-5.373E-04

-1.257E-04

-1.126E-03

A20

-9.875E-07

6.406E-07

1.423E-05

4.435E-05

0.000E+00

7.735E-05

Face number

S7

S8

S9

S10

S11

S12

K

0.000E+00

-1.000E+01

8.000E+00

0.000E+00

-6.569E+00

A4

-9.178E-03

1.391E-02

1.175E-02

-1.344E-02

-2.176E-02

-1.798E-02

A6

-4.640E-02

-8.486E-02

-7.357E-02

-1.917E-02

9.211E-03

1.071E-02

A8

7.001E-02

1.156E-01

8.901E-02

2.024E-02

-1.216E-02

-1.487E-02

A10

-7.844E-02

-1.060E-01

-6.582E-02

-1.092E-02

1.077E-02

9.482E-03

A12

5.813E-02

6.441E-02

3.034E-02

3.863E-03

-4.919E-03

-3.358E-03

A14

-2.776E-02

-2.560E-02

-8.676E-03

-9.874E-04

1.245E-03

6.974E-04

A16

8.316E-03

6.408E-03

1.410E-03

1.719E-04

-1.754E-04

-8.177E-05

A18

-1.446E-03

-9.244E-04

-1.010E-04

-1.692E-05

1.279E-05

4.833E-06

A20

1.126E-04

5.944E-05

5.973E-07

6.721E-07

-3.724E-07

-1.050E-07

Face number

S13

S14

S15

S16

S17

S18

K

2.394E+00

-4.478E+00

-1.000E+00

0.000E+00

-7.575E-01

A4

-4.403E-03

-1.223E-01

-8.004E-02

6.916E-02

-5.595E-02

-7.169E-02

A6

1.853E-02

7.684E-02

3.617E-02

-4.422E-02

2.327E-03

1.582E-02

A8

-1.853E-02

-3.481E-02

-2.046E-02

1.377E-02

2.135E-03

-2.974E-03

A10

8.610E-03

1.039E-02

7.421E-03

-2.961E-03

-3.936E-04

4.321E-04

A12

-2.441E-03

-2.050E-03

-1.814E-03

4.393E-04

2.429E-05

-4.446E-05

A14

4.412E-04

2.665E-04

2.914E-04

-4.213E-05

2.108E-07

3.040E-06

A16

-5.036E-05

-2.189E-05

-2.855E-05

2.417E-06

-1.002E-07

-1.303E-07

A18

3.337E-06

1.021E-06

1.528E-06

-7.320E-08

4.712E-09

3.163E-09

A20

-9.739E-08

-2.044E-08

-3.415E-08

8.628E-10

-7.346E-11

-3.312E-11

TTL/ImgH	1.390	ACT/TTL	0.598
				f/EPD	1.650	(SAG81-SAG72)/ET78	-1.140
f2/f123	-2.828	SD62/SD41	1.513
				f45/f67	2.767	(SD92-SD22)/\|SAG92\|	2.861
f89/f	1.628

in addition, as is clear from the aberration diagram in fig. 10, the longitudinal spherical aberration, curvature of field, and distortion of the optical system 100 are all well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Sixth embodiment

Referring to fig. 11 and 12, fig. 11 is a schematic structural diagram of an optical system 100 in a sixth embodiment, the optical system 100 includes, in order from an object side to an image side, a stop STO, a first lens L1 with positive refractive power, a second lens L2 with negative refractive power, a third lens L3 with positive refractive power, a fourth lens L4 with negative refractive power, a fifth lens L5 with negative refractive power, a sixth lens L6 with negative refractive power, a seventh lens L7 with positive refractive power, an eighth lens L8 with positive refractive power, and a ninth lens L9 with negative refractive power. Fig. 12 is a graph showing longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the sixth embodiment in order from left to right.

In addition, the parameters of the optical system 100 are given in table 11, and the definition of the parameters can be obtained in the first embodiment, which is not described herein.

TABLE 11

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Further, the aspheric coefficients of the image side or the object side of each lens of the optical system 100 are given in table 12, and the definition of each parameter can be obtained from the first embodiment, which is not described herein.

Table 12

Face number

S1

S2

S3

S4

S5

S6

K

0.000E+00

A4

-5.828E-04

-2.451E-02

-4.037E-02

-2.007E-02

-1.003E-02

1.825E-02

A6

3.991E-03

1.325E-02

1.992E-02

5.244E-03

-1.373E-03

-1.017E-01

A8

-6.205E-03

-1.329E-03

-4.643E-03

9.889E-03

-4.795E-04

1.669E-01

A10

6.284E-03

-4.293E-03

6.223E-04

-1.590E-02

-2.778E-03

-1.834E-01

A12

-3.959E-03

4.044E-03

-1.025E-03

1.301E-02

3.253E-03

1.305E-01

A14

1.565E-03

-1.922E-03

1.064E-03

-6.601E-03

-1.843E-03

-5.961E-02

A16

-3.781E-04

5.237E-04

-4.765E-04

2.090E-03

5.337E-04

1.694E-02

A18

5.108E-05

-7.726E-05

1.043E-04

-3.783E-04

-5.958E-05

-2.728E-03

A20

-3.013E-06

4.769E-06

-9.076E-06

3.129E-05

0.000E+00

1.901E-04

Face number

S7

S8

S9

S10

S11

S12

K

0.000E+00

1.000E+01

2.800E+01

0.000E+00

1.343E+01

A4

1.852E-02

2.304E-02

9.639E-03

-4.083E-03

6.296E-03

6.606E-03

A6

-1.196E-01

-9.803E-02

-6.504E-02

-3.706E-02

-4.354E-02

-3.922E-02

A8

1.665E-01

1.227E-01

7.606E-02

3.544E-02

3.780E-02

2.564E-02

A10

-1.550E-01

-1.028E-01

-5.516E-02

-1.712E-02

-1.536E-02

-8.965E-03

A12

9.489E-02

5.782E-02

2.640E-02

4.763E-03

2.944E-03

1.809E-03

A14

-3.770E-02

-2.182E-02

-8.831E-03

-8.621E-04

-1.060E-04

-2.170E-04

A16

9.490E-03

5.331E-03

2.006E-03

1.207E-04

-4.996E-05

1.945E-05

A18

-1.411E-03

-7.665E-04

-2.741E-04

-1.301E-05

7.277E-06

-1.723E-06

A20

9.721E-05

4.961E-05

1.685E-05

7.228E-07

-2.871E-07

8.970E-08

Face number

S13

S14

S15

S16

S17

S18

K

2.394E+00

5.121E+00

-1.000E+00

0.000E+00

-7.744E-01

A4

1.486E-02

-9.656E-02

-5.224E-02

7.786E-02

-5.513E-02

-7.400E-02

A6

-1.159E-02

6.501E-02

1.901E-02

-5.422E-02

5.496E-03

1.772E-02

A8

5.007E-07

-3.271E-02

-1.418E-02

1.818E-02

1.738E-04

-3.639E-03

A10

2.178E-03

1.115E-02

6.053E-03

-4.043E-03

1.182E-04

5.597E-04

A12

-1.045E-03

-2.519E-03

-1.578E-03

6.052E-04

-5.028E-05

-5.949E-05

A14

2.459E-04

3.683E-04

2.535E-04

-5.854E-05

6.718E-06

4.148E-06

A16

-3.310E-05

-3.320E-05

-2.408E-05

3.436E-06

-4.387E-07

-1.802E-07

A18

2.468E-06

1.667E-06

1.236E-06

-1.091E-07

1.441E-08

4.407E-09

A20

-7.882E-08

-3.553E-08

-2.637E-08

1.409E-09

-1.916E-10

-4.628E-11

in addition, as is clear from the aberration diagram in fig. 12, the longitudinal spherical aberration, curvature of field, and distortion of the optical system 100 are all well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Seventh embodiment

Referring to fig. 13 and 14, fig. 13 is a schematic structural diagram of an optical system 100 in a seventh embodiment, wherein the optical system 100 sequentially includes, from an object side to an image side, a stop STO, a first lens L1 with positive 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 negative refractive power, a sixth lens L6 with positive refractive power, a seventh lens L7 with negative refractive power, an eighth lens L8 with positive refractive power, and a ninth lens L9 with negative refractive power. Fig. 14 is a graph showing longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the seventh embodiment in order from left to right.

the fourth lens element L4 has a convex object-side surface S7 at a paraxial region 110 and a concave object-side surface at a peripheral region;

In addition, the parameters of the optical system 100 are given in table 13, and the definition of the parameters can be obtained in the first embodiment, which is not described herein.

TABLE 13

Further, the aspheric coefficients of the image side or the object side of each lens in the optical system 100 are given in table 14, and the definition of each parameter can be obtained from the first embodiment, which is not described herein.

TABLE 14

TTL/ImgH	1.390	ACT/TTL	0.596
				f/EPD	1.660	(SAG81-SAG72)/ET78	0.063
f2/f123	-2.563	SD62/SD41	1.417
				f45/f67	8.670	(SD92-SD22)/\|SAG92\|	2.856
f89/f	1.751

in addition, as is clear from the aberration diagram in fig. 14, the longitudinal spherical aberration, curvature of field, and distortion of the optical system 100 are all well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Eighth embodiment

Referring to fig. 15 and 16, fig. 15 is a schematic structural diagram of an optical system 100 in an eighth embodiment, wherein the optical system 100 sequentially includes, from an object side to an image side, a stop STO, a first lens L1 with positive refractive power, a second lens L2 with negative refractive power, a third lens L3 with positive refractive power, a fourth lens L4 with negative refractive power, a fifth lens L5 with negative refractive power, a sixth lens L6 with negative refractive power, a seventh lens L7 with negative refractive power, an eighth lens L8 with positive refractive power, and a ninth lens L9 with negative refractive power. Fig. 16 is a graph showing longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the eighth embodiment in order from left to right.

the fourth lens element L4 has a convex object-side surface S7 at a paraxial region 110 and a convex object-side surface at a peripheral region;

the image-side surface S10 of the fifth lens element L5 is concave at the paraxial region 110 and convex at the peripheral region;

the object side surface S13 of the seventh lens element L7 is convex at the paraxial region 110 and concave at the peripheral region;

the image-side surface S14 of the seventh lens element L7 is concave at the paraxial region 110 and convex at the peripheral region;

the object side surface S17 of the ninth lens element L9 is concave at the paraxial region 110 and convex at the peripheral region;

In addition, the parameters of the optical system 100 are given in table 15, and the definition of the parameters can be obtained in the first embodiment, which is not described herein.

TABLE 15

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Further, the aspheric coefficients of the image side or the object side of each lens in the optical system 100 are given in table 16, and the definition of each parameter can be obtained from the first embodiment, which is not described herein.

Table 16

TTL/ImgH	1.401	ACT/TTL	0.613
				f/EPD	1.482	(SAG81-SAG72)/ET78	-18.201
f2/f123	-4.043	SD62/SD41	1.421
				f45/f67	4.305	(SD92-SD22)/\|SAG92\|	2.964
f89/f	1.311

In addition, as is clear from the aberration diagram in fig. 16, the longitudinal spherical aberration, curvature of field, and distortion of the optical system 100 are all well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Referring to fig. 17, in some embodiments, the optical system 100 may be assembled with the photosensitive element 210 to form the image capturing module 200. At this time, the photosensitive surface of the photosensitive element 210 can be regarded as the image surface S21 of the optical system 100. The image capturing module 200 may further be provided with an infrared cut filter L10, where the infrared cut filter L10 is disposed between the image side surface S18 and the image surface S21 of the ninth lens element L9. Specifically, the photosensitive element 210 may be a charge coupled element (Charge Coupled Device, CCD) or a complementary metal oxide semiconductor device (Complementary Metal-Oxide Semiconductor Sensor, CMOS Sensor). The optical system 100 is used in the image capturing module 200, which can satisfy the requirements of high image capturing performance and miniaturization design.

Referring to fig. 17 and 18, in some embodiments, the image capturing module 200 can be applied to an electronic device 300, which includes a housing 310, and the image capturing module 200 is disposed on the housing 310. Specifically, the electronic device 300 may be, but is not limited to, a portable telephone, a video phone, a smart phone, an electronic book reader, a vehicle-mounted image pickup device such as a car recorder, or a wearable device such as a smart watch. When the electronic device 300 is a smart phone, the housing 310 may be a middle frame of the electronic device 300. The adoption of the image capturing module 200 in the electronic device 300 can satisfy the requirements of high image capturing performance and miniaturization design.

The technical features of the above-described embodiments may be arbitrarily combined, and all possible combinations of the technical features in the above-described embodiments are not described for brevity of description, however, as long as there is no contradiction between the combinations of the technical features, they should be considered as the scope of the description.

The above examples illustrate only a few embodiments of the invention, which are described in detail and are not to be construed as limiting the scope of the invention. It should be noted that it will be apparent to those skilled in the art that several variations and modifications can be made without departing from the spirit of the invention, which are all within the scope of the invention. Accordingly, the scope of protection of the present invention is to be determined by the appended claims.

Claims

1. An optical system, characterized in that the number of lenses with refractive power in the optical system is nine, and the optical system sequentially comprises, from an object side to an image side along an optical axis:

A third lens element with refractive power;

a fourth lens element with refractive power;

a fifth lens element with refractive power;

a sixth lens element with refractive power;

and the optical system satisfies the following conditional expression:

1.35≤TTL/ImgH≤1.41；

-18.3≤(SAG81-SAG72)/ET78≤0.7；

wherein TTL is the distance between the object side surface of the first lens element and the imaging surface of the optical system on the optical axis, imgH is half of the image height corresponding to the maximum field angle of the optical system, SAG81 is the sagittal height of the object side surface of the eighth lens element at the maximum effective aperture, SAG72 is the sagittal height of the image side surface of the seventh lens element at the maximum effective aperture, and ET78 is the distance between the image side surface of the seventh lens element at the maximum effective aperture and the object side surface of the eighth lens element at the maximum effective aperture in the optical axis direction.

2. The optical system according to claim 1, wherein the following conditional expression is satisfied:

1.4≤f/EPD≤1.8；

where f is the effective focal length of the optical system and EPD is the entrance pupil diameter of the optical system.

3. The optical system according to claim 1, wherein the following conditional expression is satisfied:

-6≤f2/f123≤-2.5；

wherein f2 is an effective focal length of the second lens, and f123 is a combined focal length of the first lens, the second lens, and the third lens.

4. The optical system according to claim 1, wherein the following conditional expression is satisfied:

1≤f45/f67≤9；

wherein f45 is a combined focal length of the fourth lens and the fifth lens, and f67 is a combined focal length of the sixth lens and the seventh lens; and/or

The optical system satisfies the following conditional expression:

1≤f89/f≤7.5；

wherein f89 is a combined focal length of the eighth lens and the ninth lens, and f is an effective focal length of the optical system.

5. The optical system according to claim 1, wherein the following conditional expression is satisfied:

0.55≤ACT/TTL≤0.65；

wherein ACT is the sum of thicknesses of the lenses in the optical system on the optical axis.

6. The optical system of claim 1, wherein the object side and the image side of each lens in the optical system are aspheric.

7. The optical system according to claim 1, wherein the following conditional expression is satisfied:

1.3≤SD62/SD41≤1.6；

the SD62 is half of the maximum effective aperture of the image side surface of the sixth lens element, and the SD41 is half of the maximum effective aperture of the object side surface of the fourth lens element.

8. The optical system according to claim 1, wherein the following conditional expression is satisfied:

2.8≤(SD92-SD22)/|SAG92|≤3.8；

wherein SD92 is half of the maximum effective aperture of the image side of the ninth lens, SD22 is half of the maximum effective aperture of the image side of the second lens, and SAG92 is the sagittal height of the image side of the ninth lens at the maximum effective aperture.

9. An image capturing module comprising a photosensitive element and the optical system of any one of claims 1-8, wherein the photosensitive element is disposed on an image side of the optical system.

10. An electronic device, comprising a housing and the image capturing module of claim 9, wherein the image capturing module is disposed on the housing.