CN112987257B

CN112987257B - Optical imaging system, image capturing module and electronic equipment

Info

Publication number: CN112987257B
Application number: CN202110339123.8A
Authority: CN
Inventors: 华露; 杨健; 李明
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2021-03-30
Filing date: 2021-03-30
Publication date: 2022-06-24
Anticipated expiration: 2041-03-30
Also published as: CN112987257A

Abstract

The present application relates to the field of optical imaging technologies, and in particular, to an optical imaging system, an image capturing module and an electronic device. The image side of the object side comprises: a first lens having a positive refractive power, a second lens having a negative refractive power, a third lens having a positive refractive power, a fourth lens having a refractive power, and a fifth lens having a refractive power, an object-side surface of the fifth lens being concave at a paraxial region, and an image-side surface of the fifth lens being convex at a paraxial region; a sixth lens having a focal power, a seventh lens having a negative focal power, an image-side surface of the seventh lens being concave at a paraxial region; an eighth lens having a refractive power, an object-side surface of the eighth lens being convex at a paraxial region; and the ninth lens has optical power, the object side surface of the ninth lens is convex at a paraxial region, and the image side surface of the ninth lens is concave at the paraxial region. The optical imaging system in the application can improve the imaging effect of the optical imaging system.

Description

Optical imaging system, image capturing module and electronic equipment

Technical Field

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

Background

With the increase of the internet coverage area and the development of the internet technology, the updating cycle of the main terminal bearing the internet application of the mobile phone is shorter and shorter, the shooting function of the mobile phone is stronger and stronger, besides the continuous improvement of pixels, the types of lenses capable of adapting to different shooting environments are more and more, meanwhile, the requirement on the single type of lenses is stricter, and the whole trend that the mobile phone lens is developed to the professional camera lens is presented. The telephoto lens has a long focal length, so that a shallower depth of field can be obtained, and further, far scene details can be better processed, and the imaging effect of distance compression is achieved.

However, the existing telephoto lens mobile phone has a poor imaging effect, so that the photographing effect is poor, and the user experience is affected.

Disclosure of Invention

The application provides an optical imaging system, and the imaging effect of the optical imaging system is better.

In order to achieve the above object, the present application provides an optical imaging system, comprising, in order from an object side to an image side:

a first lens element having a positive optical power, an object-side surface of the first lens element being convex at a paraxial region and an image-side surface of the first lens element being concave at a paraxial region;

a second lens element having a negative optical power, an object-side surface of the second lens element being convex at a paraxial region and an image-side surface of the second lens element being concave at a paraxial region;

a third lens having positive optical power, an object side surface of the third lens being convex at a paraxial region;

a fourth lens having a focal power, an image side surface of the fourth lens being concave at a paraxial region;

a fifth lens element having a focal power, an object-side surface of the fifth lens element being concave at a paraxial region and an image-side surface of the fifth lens element being convex at a paraxial region;

a sixth lens element having a focal power, an object-side surface of the sixth lens element being concave at a paraxial region and an image-side surface of the sixth lens element being convex at a paraxial region;

a seventh lens having a negative optical power, an image side surface of the seventh lens being concave at a paraxial region;

an eighth lens having a refractive power, an object side surface of the eighth lens being convex at a paraxial region;

a ninth lens having a power, an object-side surface of the ninth lens being convex at a paraxial region, an image-side surface of the ninth lens being concave at a paraxial region.

The object-side surface and the image-side surface of the ninth lens element are aspheric, and at least one of the object-side surface and the image-side surface of the ninth lens element has at least one inflection point.

In the optical imaging system, the first lens has positive focal power, the object side surface of the first lens is convex at a position near an optical axis, and the image side surface of the first lens is concave at a position near the optical axis, so that the effect of correcting aberration of the first lens is improved, the first lens is ensured to have proper thickness, and the effect of reasonably matching with the rear lens can be achieved during assembly; the second lens has negative focal power, the object side surface of the second lens is a convex surface at a paraxial region, and the image side surface of the second lens is a concave surface at the paraxial region, so that the second lens has stronger negative bending force, and the miniaturization of the optical imaging system is favorably realized; the fifth lens has a focal power, the object side surface of the fifth lens is concave at a paraxial region, and the image side surface of the fifth lens is convex at the paraxial region; the reasonable deflection of the light on the object side surface of the fifth lens is facilitated, particularly the reasonable angle of the light in the external view field can ensure that the external view field obtains higher relative illumination and good imaging quality is ensured; the seventh lens has negative focal power, and the image side surface of the seventh lens is concave at a paraxial region; the total length of the optical imaging system is favorably shortened, the aberration generated by the front lens is corrected, and the aberration balance of the optical imaging system is favorably maintained; the eighth lens has focal power, and the object side surface of the eighth lens is convex at a paraxial region; the object side surface of the eighth lens is provided with an inflection point, and the inflection point is matched with the inflection point on the lateral surface of the seventh lens, so that aberration can be corrected, and imaging quality can be improved; the ninth lens has optical power, and the object-side surface of the ninth lens is convex at a paraxial region and the image-side surface of the ninth lens is concave at the paraxial region; the ninth lens is favorable for better converging the light of the central field of view to the center of the image plane, plays a role of a base pad for the imaging of the whole image plane, has an aberration correction effect and ensures high imaging quality together with the front lens. Therefore, the imaging effect of the optical imaging system can be improved by the arrangement mode of the focal powers of the first lens to the ninth lens and the arrangement mode of the image side surface and the object side surface of the first lens to the ninth lens.

Preferably, the optical imaging system satisfies the following conditional expression:

6<f2/(r22-r21)<14.5；

wherein f2 is the second lens effective focal length; r22 is the curvature radius of the image side surface of the second lens at the optical axis; r21 is the radius of curvature of the object-side surface of the second lens at the optical axis.

By satisfying the limitation of the conditional expression and reasonably configuring the relationship between the effective focal length of the second lens and the object-side curvature radius of the second lens, the second lens can generate enough negative refractive power to balance the aberrations generated by the first lens, the third lens and the fourth lens in the positive direction; in addition, the shape of the object side image side surface of the second lens can be effectively controlled to have a proper curvature, and the sensitivity and the processing difficulty of the second lens are reduced. When f2/(r22-r21) is not less than 14.5, the negative refractive power provided by the second lens element is not sufficient to balance the positive refractive power of the front lens element, which is not favorable for the total aberration correction; when f2/(r22-r21) ≦ 6, the difference between the object-side curvature radii of the second lens is too large, which may cause too large difference between the surface curvatures of the second lens, which is not enough to obtain a proper deflection angle for light, and is not favorable for shortening the total optical length, and limiting the image height, which affects the imaging quality; on the other hand, the second lens surface is too curved, which increases the difficulty of lens molding and assembling.

15<f7/sag72<120；

wherein f7 is the seventh lens effective focal length; sag72 is the sagittal height of the image side surface of the seventh lens at the maximum effective diameter.

By satisfying the limitation of the conditional expression, the ratio of the effective focal length of the seventh lens to the image side rise of the seventh lens is controlled within a reasonable range, the surface shape of the seventh lens is favorably controlled, the seventh lens is matched and complemented with the front lens and the rear lens in shape and aberration correction, light can smoothly transit in the rear lens group to reach an image surface at a reasonable incidence angle, and the high imaging quality of an on-axis field of view can be ensured.

15<r81/|sag81|<135；

wherein r81 is a radius of curvature of the object-side surface of the eighth lens at the optical axis; sag81 is the rise of the eighth lens object-side at the maximum effective diameter.

By satisfying the limitation of the conditional expression, the ratio of the curvature radius of the object side of the eighth lens to the rise of the object side of the eighth lens is configured to be in a reasonable range, which is helpful for restraining the shape trend and the face-type inclination angle of the eighth lens, and provides the optical imaging system with a proper focal length contribution amount, thereby realizing the long-focus characteristic. When r81/| sag81| ≧ 135, the eighth lens profile is insufficiently curved, tends to be gentle, and provides a telephoto characteristic with insufficient refractive power to support the overall system; when r81/| sag81| is less than or equal to 15, the surface shape of the eighth lens is too curved, which easily causes the light deflection angle of the marginal field of view to be too large, and the light angle incident on the image surface of the eighth lens to be too large, and finally causes the quality of marginal imaging to be reduced.

EFL/TTL>1；

the EFL is an effective focal length of the optical imaging system, and the TTL is a distance from an object-side surface of the first lens element to an imaging surface of the optical imaging system on an optical axis.

By satisfying the limitation of the conditional expression, the optical imaging system can obtain the long-focus characteristic, and meanwhile, the optical imaging system can have a relatively compact structure by reducing the total length of the optical imaging system, so that the miniaturization and the portability of the lens are realized.

f1/sd11<4.2；

wherein f1 is the effective focal length of the first lens; sd11 is the maximum effective half aperture of the object-side face of the first lens.

Through the restriction that satisfies the conditional expression, the ratio of control first lens effective focal length and the biggest effective half bore of first lens objective side is favorable to keeping under the long-focus prerequisite, increases the angle of view, and the control to first lens bore and face type can compress the light incident angle in addition, reduces the pupil aberration, and then helps promoting the formation of image quality. When f1/sd11 is larger than or equal to 4.2, the first lens element provides too small positive refractive power, which is not favorable for compressing the light incident angle, and the rear lens element is not easy to achieve spherical aberration correction balance, finally resulting in reduced imaging quality.

0.32<BFL/sd92<0.4；

the BFL is the minimum distance from the image side surface of the ninth lens to the imaging surface of the optical imaging system in the optical axis direction, namely the back focus; sd92 is the maximum effective half aperture of the image side surface of the ninth lens.

Through the limitation that satisfies the conditional expression, the projection height of light at the ninth lens can be guaranteed to the ratio of rationally configured back focal and the maximum effective half bore of the image side of the ninth lens, and then sufficient luminous flux is obtained, so that the outer view field has higher relative illuminance.

IMGH*2/TTL>0.93；

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

Satisfying the restrictions of the conditional expressions makes it possible to realize telephoto imaging while maintaining a large image plane with a small size. In addition, the large image surface is also beneficial to better showing the details of the shot object, and further the imaging quality is improved.

tan(FOV/2)/ct19>0.12mm^-1；

wherein the FOV is a maximum field angle of the optical imaging system; ct19 is the sum of the thicknesses of the first lens to the ninth lens on the optical axis.

By satisfying the limitation of the conditional expression, the ratio of the maximum field angle to the sum of the thicknesses of the nine lenses on the optical axis is controlled to be more than 0.12, which is beneficial to shortening the total length of the system and realizing the ultrathin characteristic. When tan (FOV/2)/ct19 is less than or equal to 0.12, miniaturization of the optical imaging system is not facilitated, and the smaller field of view range will also reduce user experience.

1.3<aet14/at14<1.75；

aet14 is the sum of air gaps of the maximum effective semi-calibers of the first lens to the fourth lens in the optical axis direction; at14 is the sum of the air gaps on the optical axis of the first lens to the fourth lens.

The ratio is reasonably controlled by satisfying the limitation of the conditional expression, the total length of the system is favorably shortened, and each lens in the front lens group has reasonable air gaps at the optical axis and the maximum effective semi-aperture, so that the distance between the lenses is not too small to increase the difficulty in assembling the lenses; the distance is not too large to allow reasonable transition of light and the total optical length cannot be further compressed. When aet14/at14 is larger than or equal to 1.75, the air gap between the adjacent lenses of the front lens group at the maximum effective semi-caliber position is too large, so that the thickness difference of the thick edge in the lenses is increased, the thickness distribution of the lenses is uneven, the stability of the lenses is reduced, namely, the thin part is easy to crack in the later-stage lens assembling process, and the production cost is increased; when aet14/at14 is less than or equal to 1.3, the lens arrangement is too tight, the assembly process is easy to extrude, and the assembly difficulty is increased.

The application also provides an image capturing module, which comprises any one of the optical systems and has good imaging quality.

This application still provides an electronic equipment, get for instance the module including casing and the aforesaid, get for instance the module and locate in the casing, get for instance the module through adopting the aforesaid, electronic equipment can possess good camera performance.

Drawings

Fig. 1 is a schematic configuration diagram of an optical imaging system according to a first embodiment of the present invention;

FIG. 2 is a schematic diagram of a longitudinal spherical aberration diagram, an astigmatism graph and distortion of the optical imaging system of the first embodiment of the present invention;

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

FIG. 4 is a schematic diagram of a longitudinal spherical aberration diagram, an astigmatism graph and distortion of an optical imaging system according to a second embodiment of the invention;

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

FIG. 6 is a schematic diagram of a longitudinal spherical aberration diagram, an astigmatism graph and distortion of an optical imaging system according to a third embodiment of the invention;

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

FIG. 8 is a schematic diagram of a longitudinal spherical aberration diagram, an astigmatism graph and distortion of an optical imaging system according to a fourth embodiment of the invention;

FIG. 9 is a schematic configuration diagram of an optical imaging system according to a fifth embodiment of the present invention;

fig. 10 is a schematic view of a longitudinal spherical aberration diagram, an astigmatism graph and distortion of an optical imaging system of a fifth embodiment of the present invention;

FIG. 11 is a schematic configuration diagram of an optical imaging system according to a sixth embodiment of the present invention;

fig. 12 is a schematic diagram of a longitudinal spherical aberration diagram, an astigmatism graph and distortion of an optical imaging system according to a sixth embodiment of the present invention.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Referring to fig. 1, an optical imaging system according to the present application includes, in order from an object side to an image side:

a first lens element 1 having positive optical power, an object-side surface S2 of the first lens element 1 being convex at a paraxial region, and an image-side surface S3 of the first lens element 1 being concave at a paraxial region;

a second lens 2 having a negative optical power, an object-side surface S4 of the second lens 2 being convex at a paraxial region, an image-side surface of the second lens 2 being concave at a paraxial region S5;

a third lens 3 having positive optical power, an object side surface S6 of the third lens 3 being convex at a paraxial region;

a fourth lens 4 having optical power, an image side surface S9 of the fourth lens 4 being concave at a paraxial region;

a fifth lens 5 having optical power, an object-side surface S11 of the fifth lens 5 being concave at a paraxial region, an image-side surface S12 of the fifth lens 5 being convex at a paraxial region;

a sixth lens 6 having optical power, an object side surface S13 of the sixth lens 6 being concave at a paraxial region, an image side surface S14 of the sixth lens 6 being convex at a paraxial region;

a seventh lens 7 having a negative optical power, an image-side surface S16 of the seventh lens 7 being concave at a paraxial region;

an eighth lens 8 having optical power, an object side surface S17 of the eighth lens 8 being convex at a paraxial region;

a ninth lens element 9 having optical power, an object-side surface S19 of the ninth lens element 9 being convex at a paraxial region, and an image-side surface S20 of the ninth lens element 9 being concave at a paraxial region.

In the optical imaging system of the present application, the first lens element 1 has positive focal power, and the object-side surface S2 of the first lens element 1 is convex at the paraxial region, and the image-side surface S3 is concave at the paraxial region, which is beneficial to improving the aberration correcting effect of the first lens element 1, and also can ensure that the first lens element 1 has a proper thickness, and can achieve the effect of reasonably matching with the rear lens element when assembled; the second lens element 2 has negative power, and the object-side surface S4 of the second lens element 2 is convex at the paraxial region and the image-side surface S5 is concave at the paraxial region, so that the second lens element 2 has strong negative bending strength, which is beneficial to realizing miniaturization of the optical imaging system; the fifth lens element 5 has optical power, the object-side surface S11 of the fifth lens element 5 being concave at the paraxial region and the image-side surface S12 being convex at the paraxial region; the reasonable deflection of the light on the object side surface of the fifth lens 5 is facilitated, especially the reasonable angle of the light in the external view field can ensure that the external view field obtains higher relative illumination and ensures good imaging quality; the seventh lens element 7 has negative power, and the image-side surface S15 of the seventh lens element 7 is concave at the paraxial region; the total length of the optical imaging system is favorably shortened, the aberration generated by the front lens is corrected, and the aberration balance of the optical imaging system is favorably maintained; the eighth lens element 8 has optical power, and the object-side surface S17 of the eighth lens element 8 is convex at the paraxial region; the object side surface of the eighth lens 8 is provided with an inflection point, and the inflection point is matched with the inflection point of the image side surface S16 of the seventh lens 7, so that aberration can be corrected, and imaging quality can be improved; the ninth lens element 9 has optical power, and the object-side surface S19 of the ninth lens element 9 is convex at the paraxial region and the image-side surface S20 is concave at the paraxial region; the ninth lens 9 is beneficial to better converging the central field-of-view light to the center of the image plane, plays a role of a base pad for imaging the whole image plane, has an aberration correction effect and ensures high imaging quality together with the front lens. Therefore, the imaging effect of the optical imaging system is improved by the arrangement of the powers of the first lens 1 to the ninth lens 9 and the arrangement of the image side surface and the object side surface of the first lens 1 to the ninth lens 9.

In some embodiments, the object-side surface S19 and the image-side surface S20 of the ninth lens 9 are aspheric, and at least one of the object-side surface S19 and the image-side surface S20 of the ninth lens 9 is provided with at least one inflection point, and the first lens 1 is further provided with a first stop S1, a second stop S10 is disposed between the fourth lens 4 and the fifth lens 5, and an infrared cut filter is disposed between the ninth lens 9 and the image surface S23.

The first diaphragm S1 and the second diaphragm S10 are aperture diaphragms for controlling the amount of light entering the optical system 10 and at the same time can function to block ineffective light.

The aspherical surface has a surface shape determined by the following formula:

wherein Z is the longitudinal distance between any point on the aspheric surface and the surface vertex, r is the distance between any point on the aspheric surface and the optical axis, the vertex curvature (the reciprocal of the curvature radius) of c, k is a conic constant, and Ai is the correction coefficient of the i-th order of the aspheric surface.

In some embodiments, the optical imaging system satisfies the following conditional expression:

6<f2/(r22-r21)<14.5；

wherein f2 is the effective focal length of the second lens 2; r22 is the curvature radius of the image side surface of the second lens 2; r21 is the radius of curvature of the object side of the second lens 2. That is, f2/(r22-r21) may have any value within the range of (6, 14.5), and for example, may have values of 6.458, 7.014, 9.107, 10.976, 11.572, 14.057, and the like.

The relationship between the effective focal length of the second lens element 2 and the curvature radius of the object side of the second lens element 2 is reasonably configured to satisfy the above conditional expressions, so that the second lens element 2 can generate enough negative refractive power to balance the aberration generated by the first lens element 1, the third lens element 3 and the fourth lens element 4 in the positive direction; in addition, the shape of the side surface of the object side of the second lens 2 can be effectively controlled to have proper curvature, and the sensitivity and the processing difficulty of the second lens 2 are reduced. When f2/(r22-r21) ≥ 14.5, the negative refractive power provided by the second lens element 2 is insufficient to balance the positive refractive power of the front lens element, which is unfavorable for the total aberration correction; when f2/(r22-r21) ≦ 6, the difference between the radii of curvature of the object side and the image side of the second lens 2 is too large, which may cause too large difference between the degrees of curvature of the object side and the image side of the second lens 2, on one hand, not enough to obtain a proper deflection angle for the light, which is not favorable for shortening the total optical length and limiting the image height, and affects the imaging quality; on the other hand, the second lens 2 is too curved, which increases the difficulty of lens forming and assembling.

15<f7/sag72<120；

wherein f7 is the effective focal length of the seventh lens 7; sag72 is the sagittal height of the image side surface of the seventh lens at the maximum effective diameter. That is, f7/sag72 may be any value within the range of (15, 120), for example, 19.210, 25.234, 26.304, 50.383, 54.359, 116.770, and the like.

Wherein the rise is the distance from the center of the image side surface of the seventh lens element 7 (i.e., the intersection of the object side surface and the optical axis) to the maximum effective clear aperture of the surface (i.e., the maximum effective diameter of the surface) in the direction parallel to the optical axis. When the vector height value is a positive value, in a direction parallel to the optical axis of the system, the position of the maximum effective light-passing aperture of the surface is closer to the image side of the system than the position of the center of the surface; when the value is negative, the plane has a larger effective clear aperture at the object side than at the center of the plane in a direction parallel to the optical axis of the system.

By satisfying the limitation of the conditional expression, the ratio of the effective focal length of the seventh lens 7 to the image side rise of the seventh lens 7 is controlled within a reasonable range, which is beneficial to controlling the 7-face shape of the seventh lens, and the shape and aberration correction of the seventh lens are matched and complemented with the front and the rear lenses, and the seventh lens is also beneficial to smoothly transiting light rays in the rear lens group to reach an image plane at a reasonable incident angle, so that the on-axis field of view can obtain high imaging quality.

15<r81/|sag81|<135；

wherein r81 is the curvature radius of the object-side surface of the eighth lens 8 at the optical axis; sag81 is the rise of the object-side surface of the eighth lens 8 at the maximum effective diameter. r81/| sag81| may have any value within the range of (15, 135), for example, 21.97, 47.62, 60.51, 123.71, 122.90, 131.17, and the like.

By satisfying the limitation of the conditional expression, configuring the ratio of the curvature radius of the object side of the eighth lens 8 to the rise of the object side of the eighth lens 8 within a reasonable range helps to constrain the shape trend and the face tilt angle of the eighth lens 8, and provides the optical imaging system with a proper focal length contribution amount, thereby realizing the telephoto characteristic. When r81/| sag81| ≧ 135, the eighth lens element 8 is insufficiently curved in surface form and tends to be gentle, providing a telephoto characteristic with insufficient refractive power to support the overall system; when r81/| sag81| is less than or equal to 15, the surface shape of the eighth lens 8 is too curved, which easily causes the light deflection angle of the marginal field of view to be too large, and the light angle incident on the image surface of the eighth lens 8 to be too large, finally causing the quality of marginal imaging to be reduced.

EFL/TTL>1；

wherein, EFL is an effective focal length of the optical imaging system, and TTL is an axial distance from an object-side surface of the first lens element to an image plane of the optical system, that is, a distance from an intersection point of a first surface (a surface close to the object side) of the first lens element 1 and the optical axis to an image plane center. The EFL/TTL can be a value greater than 1, for example, a value of 1.01, 1.02, 1.05, etc.

f1/sd11<4.2；

wherein f1 is the effective focal length of the first lens 1; sd11 is the maximum effective half aperture of the object-side surface of the first lens 1. That is, f1/sd11 may be any value less than 4.2, for example, 4.11, 4.10, 3.96, 3.94, 3.81, or the like.

Through the restriction that satisfies the conditional expression, the ratio of the effective focal length of first lens 1 and the maximum effective half bore of first lens 1 object side is controlled, is favorable to keeping under the prerequisite of long focus, and increase field angle, the control to 1 bore of first lens and face type can compress the light incident angle in addition, reduces pupil aberration, and then helps promoting the formation of image quality. When f1/sd11 is greater than or equal to 4.2, the positive refractive power provided by the first lens element 1 is too small to compress the light incident angle, so that the rear lens element is not easy to achieve spherical aberration correction balance, and the imaging quality is reduced.

0.32<BFL/sd92<0.4；

the BFL is the minimum distance from the image side surface of the ninth lens to the imaging surface of the optical imaging system in the optical axis direction, namely the back focus; sd92 is the largest effective half aperture of the image side surface of the ninth lens 9. That is, BFL/sd92 may have any value within the range of (0.32, 0.4), for example, 0.34, 0.36, 0.37, 0.38, etc.

Through the limitation that satisfies the conditional expression, the projection height of light at ninth lens 9 can be guaranteed to the ratio of the maximum effective half bore of the image side of rational configuration back focal and ninth lens 9, and then sufficient light flux is obtained for the outer visual field has higher relative illuminance.

IMGH*2/TTL>0.93；

wherein, TTL is the distance between the object side surface of the first lens and the imaging surface of the optical system on the optical axis; ImgH is half of the maximum field angle of the optical system corresponding to the image height. That is, IMGH × 2/TTL may be any value greater than 0.93, for example, 0.937, 0.938, 0.964, and the like.

tan(FOV/2)/ct19>0.12mm^-1；

wherein the FOV is a maximum field angle of the optical imaging system; ct19 is the sum of the thicknesses of the first lens to the ninth lens on the optical axis. That is, tan (FOV/2)/ct19 may be any value greater than 0.12, for example, 0.12, 0.13, 0.14, 0.16, or the like.

In some embodiments, the optical imaging system satisfies the following conditional expression: 1.3< aet14/at14< 1.75;

aet14 represents the sum of air gaps in the optical axis direction of the maximum effective half aperture of the first lens to the fourth lens; at14 is the sum of the air gaps on the optical axis of the first lens to the fourth lens. That is, aet14/at14 may have any value within the range of (1.3, 1.75), and may have any value, for example, 1.35, 1.42, 1.43, 1.44, 1.63, 1.67, or the like.

First embodiment

Referring to fig. 1 and 2, the optical imaging system of the first embodiment comprises, in order from an object side to an image side: a first lens element 1 having positive optical power, an object-side surface S2 of the first lens element 1 being convex at a paraxial region, and an image-side surface S3 of the first lens element 1 being concave at a paraxial region; a second lens element 2 having a negative optical power, an object-side surface S4 of the second lens element 2 being convex at a paraxial region, an image-side surface S5 of the second lens element 2 being concave at a paraxial region; a third lens element 3 having positive optical power, an object-side surface S6 of the third lens element 3 being convex at a paraxial region, and an image-side surface S7 of the third lens element 3 being concave at a paraxial region; a fourth lens element 4 having a negative optical power, an image-side surface S9 of the fourth lens element 4 being concave at a paraxial region thereof, and an object-side surface S8 of the fourth lens element 4 being convex at a paraxial region thereof; a fifth lens element 5 having a negative optical power, an object-side surface S11 of the fifth lens element 5 being concave at a paraxial region, an image-side surface S12 of the fifth lens element 5 being convex at a paraxial region; a sixth lens 6 having positive optical power, an object-side surface S13 of the sixth lens 6 being concave at a paraxial region, an image-side surface S14 of the sixth lens 6 being convex at a paraxial region; a seventh lens 7 having a negative optical power, an object side surface S15 of the seventh lens 7 being concave at a paraxial region; the image-side surface S16 of the seventh lens element 7 is concave at the paraxial region; an eighth lens 8 having positive optical power, an object-side surface S17 of the eighth lens 8 being convex at a paraxial region; the image-side surface S18 of the eighth lens element 8 is convex at paraxial region; a ninth lens element 9 with negative optical power, an object-side surface S19 of the ninth lens element 9 being convex at a paraxial region, and an image-side surface S20 of the ninth lens element 9 being concave at a paraxial region.

In addition, the object-side surface S2 of the first lens element 1 is concave at the circumference, and the image-side surface S3 of the first lens element 1 is convex at the circumference; the object side surface S4 of the second lens element 2 is concave at the circumference, and the image side surface S5 of the second lens element 2 is concave at the circumference; the object-side surface S6 of the third lens element 3 is concave at the circumference, and the image-side surface S7 of the third lens element 3 is convex at the circumference; the object-side surface S8 of the fourth lens element 4 is convex at the circumference, and the image-side surface S9 of the fourth lens element 4 is convex at the circumference; the object side surface S11 of the fifth lens element 5 is concave at the circumference, and the image side surface S12 of the fifth lens element 5 is concave at the circumference; the object-side surface S13 of the sixth lens element 6 is convex at its circumference, and the image-side surface S14 of the sixth lens element 6 is concave at its circumference; the object-side surface S15 of the seventh lens element 7 is convex at the circumference, and the image-side surface S16 of the seventh lens element 7 is concave at the circumference; the object-side surface S17 of the eighth lens element 8 is convex at its circumference, and the image-side surface S18 of the eighth lens element 8 is concave at its circumference; the object-side surface S19 of the ninth lens element 9 is convex at its circumference, and the image-side surface S20 of the ninth lens element 9 is convex at its circumference.

Fig. 2 is a graph of longitudinal spherical aberration, an astigmatism and a distortion of the optical imaging system in the first embodiment from left to right; in the longitudinal spherical aberration curve chart, the ordinate is a normalized field of view, and the focus deviation of each field of view is within +/-0.05 mm from the graph, which indicates that the spherical aberration of the optical imaging system is small; in the astigmatism graph, the ordinate is the image height, the unit is mm, and it is seen from the graph that the focus deviation of each field of view of the sagittal image surface S and the meridional image surface T is within ± 0.05mm, which indicates that the field curvature aberration of the optical imaging system is small; in a distortion graph, the ordinate is the image height, the unit is mm, and the distortion rate of each field of view is within +/-2.5% from the graph, which indicates that the imaging distortion of the optical imaging system is small, wherein an astigmatism graph and a distortion graph are data with the reference wavelength of 555 nm; therefore, as can be seen from fig. 2, various aberrations of the optical imaging system in the first embodiment are relatively small, so that the imaging quality is high and the imaging effect is excellent.

In the first embodiment, the effective focal length of the optical imaging system is 7.28mm for EFL, 49.05 ° for the maximum field angle FOV, 2.4 for f-number FNO, and 7.15mm for total length TTL.

The reference wavelength of the focal length of the lens in the first embodiment is 555nm, the reference wavelength of the refractive index and the abbe number is 587.56nm, and the numerical units of the Y radius, the thickness and the focal length are millimeters (mm). And the optical imaging system in the first embodiment satisfies the conditions of the following table.

TABLE 1

It should be noted that FNO is the f-number of the optical imaging system, and FOV is the maximum field angle of the optical imaging system.

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

Second embodiment

Referring to fig. 3 and 4; the optical imaging system of the second embodiment, in order from the object side to the image side, comprises: a first lens element 1 having positive optical power, an object-side surface S2 of the first lens element 1 being convex at a paraxial region, and an image-side surface S3 of the first lens element 1 being concave at a paraxial region; a second lens 2 having negative optical power, an object-side surface S4 of the second lens 2 being convex at a paraxial region, an image-side surface S5 of the second lens 2 being concave at a paraxial region; a third lens element 3 having positive optical power, an object-side surface S6 of the third lens element 3 being convex at a paraxial region, and an image-side surface S7 of the third lens element 3 being concave at a paraxial region; a fourth lens element 4 having a negative optical power, an object-side surface S8 of the fourth lens element 4 being convex at a paraxial region, an image-side surface S9 of the fourth lens element 4 being concave at a paraxial region; a fifth lens element 5 having a negative optical power, an object-side surface S11 of the fifth lens element 5 being concave at a paraxial region, an image-side surface S12 of the fifth lens element 5 being convex at a paraxial region; a sixth lens 6 having positive optical power, an object-side surface S13 of the sixth lens 6 being concave at a paraxial region, an image-side surface S14 of the sixth lens 6 being convex at the paraxial region; a seventh lens 7 having a negative optical power, an object side surface S15 of the seventh lens 7 being concave at a paraxial region, an image side surface S16 of the seventh lens 7 being concave at a paraxial region; an eighth lens 8 having positive optical power, an object-side surface S17 of the eighth lens 8 being convex at a paraxial region, an image-side surface S18 of the eighth lens 8 being concave at a paraxial region; a ninth lens element 9 having positive optical power, an object-side surface S19 of the ninth lens element 9 being convex at a paraxial region, and an image-side surface S20 of the ninth lens element 9 being concave at a paraxial region.

In addition, the object-side surface S2 of the first lens element 1 is concave at the circumference, and the image-side surface S3 of the first lens element 2 is convex at the circumference; the object-side surface S4 of the second lens element 2 is convex at the circumference, and the image-side surface S5 of the second lens element 2 is concave at the circumference; the object side surface S6 of the third lens element 3 is concave at the circumference, and the image side surface S7 of the third lens element 3 is concave at the circumference; the object-side surface S8 of the fourth lens element 4 is convex at the circumference, and the image-side surface S9 of the fourth lens element 4 is convex at the circumference; the object side surface S11 of the fifth lens element 5 is concave at the circumference, and the image side surface S12 of the fifth lens element 5 is concave at the circumference; the object-side surface S13 of the sixth lens element 6 is convex at its circumference, and the image-side surface S14 of the sixth lens element 6 is concave at its circumference; the object-side surface S15 of the seventh lens element 7 is convex at the circumference, and the image-side surface S16 of the seventh lens element 7 is concave at the circumference; the object-side surface S17 of the eighth lens element 8 is concave at the circumference, and the image-side surface S18 of the eighth lens element 8 is convex at the circumference; the object-side surface S19 of the ninth lens element 9 is convex at its circumference, and the image-side surface S20 of the ninth lens element 9 is convex at its circumference.

As can be seen from the aberration diagram in fig. 4, the longitudinal spherical aberration, curvature of field, and distortion of the optical system are well controlled, so that the optical system of this embodiment has good imaging quality. In the second embodiment, the effective focal length of the optical imaging system is 7.27mm for EFL, 49.11 ° for the maximum field angle FOV, 2.19 for f-number FNO, and 7.15mm for total length TTL.

The reference wavelength of the focal length of the lens in the second embodiment is 555nm, the reference wavelength of the refractive index and the abbe number is 587.56nm, and the numerical units of the radius Y, the thickness and the focal length are all millimeters (mm). And the optical imaging system in the second embodiment satisfies the conditions of the following table.

TABLE 3

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

Third embodiment

Referring to fig. 5 and 6, the optical imaging system of the third embodiment comprises, in order from the object side to the image side: a first lens element 1 having positive optical power, an object-side surface S2 of the first lens element 1 being convex at a paraxial region, and an image-side surface S3 of the first lens element 1 being concave at a paraxial region; a second lens element 2 having a negative optical power, an object-side surface S4 of the second lens element 2 being convex at a paraxial region, an image-side surface S5 of the second lens element 2 being concave at a paraxial region; a third lens element 3 having positive optical power, an object-side surface S6 of the third lens element 3 being convex at a paraxial region, and an image-side surface S7 of the third lens element 3 being concave at a paraxial region; a fourth lens 4 having negative optical power, an object-side surface S8 of the fourth lens 4 being convex at a paraxial region, an image-side surface S9 of the fourth lens 4 being concave at a paraxial region; a fifth lens element 5 having a negative optical power, an object-side surface S11 of the fifth lens element 5 being concave at a paraxial region, an image-side surface S12 of the fifth lens element 5 being convex at a paraxial region; a sixth lens 6 having positive optical power, an object-side surface S13 of the sixth lens 6 being concave at a paraxial region, an image-side surface S14 of the sixth lens 6 being convex at a paraxial region; a seventh lens 7 having a negative optical power, an object-side surface S15 of the seventh lens 7 being concave at a paraxial region, an image-side surface S16 of the seventh lens 7 being concave at a paraxial region; an eighth lens 8 having positive optical power, an object-side surface S17 of the eighth lens 8 being convex at a paraxial region, an image-side surface S18 of the eighth lens 8 being concave at a paraxial region; a ninth lens element 9 with negative optical power, an object-side surface S19 of the ninth lens element 9 being convex at a paraxial region, and an image-side surface S20 of the ninth lens element 9 being concave at a paraxial region.

In addition, the object-side surface S2 of the first lens element 1 is concave at the circumference, and the image-side surface S3 of the first lens element 1 is convex at the circumference; the object-side surface S4 of the second lens element 2 is concave at the circumference, and the image-side surface S5 of the second lens element 2 is convex at the circumference; the object-side surface S6 of the third lens element 3 is concave at the circumference, and the image-side surface S7 of the third lens element 3 is convex at the circumference; the object-side surface S8 of the fourth lens element 4 is convex at the circumference, and the image-side surface S9 of the fourth lens element 4 is concave at the circumference; the object-side surface S11 of the fifth lens element 5 is concave at the circumference, and the image-side surface S12 of the fifth lens element 5 is convex at the circumference; the object-side surface S13 of the sixth lens element 6 is convex at its circumference, and the image-side surface S14 of the sixth lens element 6 is concave at its circumference; the object-side surface S15 of the seventh lens element 7 is convex at its circumference, and the image-side surface S16 of the seventh lens element 8 is concave at its circumference; the object-side surface S17 of the eighth lens element 8 is concave at the circumference, and the image-side surface S18 of the eighth lens element 8 is convex at the circumference; the object-side surface S19 of the ninth lens element 9 is concave at the circumference, and the image-side surface S20 of the ninth lens element 9 is convex at the circumference.

As can be seen from the aberration diagram in fig. 6, the longitudinal spherical aberration, curvature of field, and distortion of the optical system are well controlled, so that the optical system of this embodiment has good imaging quality. In the third embodiment, the effective focal length of the optical imaging system is 7.19mm for EFL, 49.57 ° for the maximum field angle FOV, 2.11 for f-number FNO, and 7.14mm for total length TTL.

The reference wavelength of the focal length of the lens of the third embodiment was 555nm, the reference wavelength of the refractive index and the abbe number was 587.56nm, and the numerical units of the Y radius, the thickness, and the focal length were millimeters (mm). And the optical imaging system in the third embodiment satisfies the conditions of the following table.

TABLE 5

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

Fourth embodiment

Refer to fig. 7 and 8; the optical imaging system of the fourth embodiment, in order from the object side to the image side, comprises: a first lens element 1 having positive optical power, an object-side surface S2 of the first lens element 1 being convex at a paraxial region, and an image-side surface S3 of the first lens element 1 being concave at a paraxial region; a second lens element 2 having a negative optical power, an object-side surface S4 of the second lens element 2 being convex at a paraxial region, an image-side surface S5 of the second lens element 2 being concave at a paraxial region; a third lens 3 having positive optical power, an object-side surface S6 of the third lens 3 being convex at a paraxial region, an image-side surface S7 of the third lens 3 being concave at a paraxial region; a fourth lens 4 having positive optical power, an object-side surface S8 of the fourth lens 4 being convex at a paraxial region, an image-side surface S9 of the fourth lens 4 being concave at a paraxial region; a fifth lens 5 having positive optical power, an object-side surface S11 of the fifth lens 5 being concave at a paraxial region, an image-side surface S12 of the fifth lens 5 being convex at a paraxial region; a sixth lens 6 having a negative optical power, an object-side surface S13 of the sixth lens 6 being concave at a paraxial region, an image-side surface S14 of the sixth lens 6 being convex at a paraxial region; a seventh lens 7 having a negative optical power, an object-side surface S15 of the seventh lens 7 being convex at a paraxial region, an image-side surface S16 of the seventh lens 7 being concave at a paraxial region; an eighth lens 8 having positive optical power, an object-side surface S17 of the eighth lens 8 being convex at a paraxial region, an image-side surface S18 of the eighth lens 8 being concave at a paraxial region; a ninth lens element 9 with negative optical power, an object-side surface S19 of the ninth lens element 9 being convex at a paraxial region, and an image-side surface S20 of the ninth lens element 9 being concave at a paraxial region.

In addition, the object-side surface S2 of the first lens element 1 is concave at the circumference, and the image-side surface S3 of the first lens element 1 is convex at the circumference; the object-side surface S4 of the second lens element 2 is convex at the circumference, and the image-side surface S5 of the second lens element 2 is concave at the circumference; the object-side surface S6 of the third lens element 3 is concave at the circumference, and the image-side surface S7 of the third lens element 3 is convex at the circumference; the object-side surface S8 of the fourth lens element 4 is convex at the circumference, and the image-side surface S9 of the fourth lens element 4 is convex at the circumference; the object-side surface S11 of the fifth lens element 5 is concave at the circumference, and the image-side surface S12 of the fifth lens element 5 is convex at the circumference; the object side surface S13 of the sixth lens element 6 is concave at the circumference, and the image side surface S14 of the sixth lens element 6 is concave at the circumference; the object-side surface S15 of the seventh lens element 7 is convex at the circumference, and the image-side surface S16 of the seventh lens element 7 is concave at the circumference; the object-side surface S17 of the eighth lens element 8 is convex at its circumference, and the image-side surface S18 of the eighth lens element 8 is concave at its circumference; the object-side surface S19 of the ninth lens element 9 is convex at its circumference, and the image-side surface S20 of the ninth lens element 9 is convex at its circumference.

As can be seen from the aberration diagram in fig. 8, the longitudinal spherical aberration, curvature of field, and distortion of the optical system are well controlled, so that the optical system of this embodiment has good imaging quality. In the fourth embodiment, the effective focal length of the optical imaging system is 7.28mm for EFL, 49.89 ° for the maximum field angle FOV, 2.30 for f-number FNO, and 7.13mm for total length TTL.

The reference wavelength of the focal length of the lens in the fourth embodiment is 555nm, the reference wavelength of the refractive index and the abbe number is 587.56nm, and the numerical units of the radius Y, the thickness and the focal length are millimeters (mm). And the optical imaging system in the fourth embodiment satisfies the conditions of the following table.

TABLE 7

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

Fifth embodiment

Refer to fig. 9 and 10; the optical imaging system of the fifth embodiment, in order from the object side to the image side, comprises: a first lens element 1 having positive optical power, an object-side surface S2 of the first lens element 1 being convex at a paraxial region, and an image-side surface S3 of the first lens element 1 being concave at a paraxial region; a second lens 2 having negative optical power, an object-side surface S4 of the second lens 2 being convex at a paraxial region, an image-side surface S5 of the second lens 2 being concave at a paraxial region; a third lens element 3 having positive optical power, an object-side surface S6 of the third lens element 3 being convex at a paraxial region, and an image-side surface S7 of the third lens element 3 being concave at a paraxial region; a fourth lens element 4 having positive optical power, an object-side surface S8 of the fourth lens element 4 being convex at a paraxial region, an image-side surface S9 of the fourth lens element 4 being concave at a paraxial region; a fifth lens element 5 having a negative optical power, an object-side surface S11 of the fifth lens element 5 being concave at a paraxial region, an image-side surface S12 of the fifth lens element 5 being convex at a paraxial region; a sixth lens 6 having a negative optical power, an object-side surface S13 of the sixth lens 6 being concave at a paraxial region, an image-side surface S14 of the sixth lens 6 being convex at a paraxial region; a seventh lens 7 having a negative optical power, an object-side surface S15 of the seventh lens 7 being convex at a paraxial region, an image-side surface S16 of the seventh lens 7 being concave at a paraxial region; an eighth lens 8 having positive optical power, an object-side surface S17 of the eighth lens 8 being convex at a paraxial region, an image-side surface S18 of the eighth lens 8 being concave at a paraxial region; a ninth lens element 9 with negative optical power, an object-side surface S19 of the ninth lens element 9 being convex at a paraxial region, and an image-side surface S20 of the ninth lens element 9 being concave at a paraxial region.

In addition, the object-side surface S2 of the first lens element 1 is concave at the circumference, and the image-side surface S3 of the first lens element 1 is convex at the circumference; the object-side surface S4 of the second lens element 2 is concave at the circumference, and the image-side surface S5 of the second lens element 2 is convex at the circumference; the object-side surface S6 of the third lens element 3 is concave at the circumference, and the image-side surface S7 of the third lens element 3 is convex at the circumference; the object-side surface S8 of the fourth lens element 4 is convex at the circumference, and the image-side surface S9 of the fourth lens element 4 is concave at the circumference; the object-side surface S11 of the fifth lens element 5 is concave at the circumference, and the image-side surface S12 of the fifth lens element 5 is convex at the circumference; the object side surface S13 of the sixth lens element 6 is concave at the circumference, and the image side surface S14 of the sixth lens element 6 is concave at the circumference; the object-side surface S15 of the seventh lens element 7 is concave at the circumference, and the image-side surface S16 of the seventh lens element 7 is convex at the circumference; the object-side surface S17 of the eighth lens element 8 is concave at the circumference, and the image-side surface S18 of the eighth lens element 8 is convex at the circumference; the object-side surface S19 of the ninth lens element 9 is convex at its circumference, and the image-side surface S20 of the ninth lens element 9 is concave at its circumference.

As can be seen from the aberration diagram in fig. 10, the longitudinal spherical aberration, curvature of field, and distortion of the optical system are well controlled, so that the optical system of this embodiment has good imaging quality. In the fifth embodiment, the effective focal length of the optical imaging system is 7.27mm for EFL, 48.91 ° for the maximum field angle FOV, 2.30 for f-number FNO, and 6.95mm for total length TTL.

The reference wavelength of the focal length of the lens in the fifth embodiment is 555nm, the reference wavelength of the refractive index and the abbe number is 587.56nm, and the numerical units of the radius Y, the thickness, and the focal length are all millimeters (mm). And the optical imaging system in the fifth embodiment satisfies the conditions of the following table.

TABLE 9

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

Sixth embodiment

Referring to fig. 11 and 12; the optical imaging system of the sixth embodiment, in order from the object side to the image side, comprises: a first lens element 1 having positive optical power, an object-side surface S2 of the first lens element 1 being convex at a paraxial region, and an image-side surface S3 of the first lens element 1 being concave at a paraxial region; a second lens element 2 having a negative optical power, an object-side surface S4 of the second lens element 2 being convex at a paraxial region, an image-side surface S5 of the second lens element 2 being concave at a paraxial region; a third lens element 3 having positive optical power, an object-side surface S6 of the third lens element 3 being convex at a paraxial region, and an image-side surface S7 of the third lens element 3 being concave at a paraxial region; a fourth lens 4 having a negative optical power, an object-side surface S8 of the fourth lens 4 being concave at a paraxial region, an image-side surface S9 of the fourth lens 4 being concave at a paraxial region; a fifth lens element 5 having a negative optical power, an object-side surface S11 of the fifth lens element 5 being concave at a paraxial region, an image-side surface S12 of the fifth lens element 5 being convex at a paraxial region; a sixth lens 6 having positive optical power, an object-side surface S13 of the sixth lens 6 being concave at a paraxial region, an image-side surface S14 of the sixth lens 6 being convex at the paraxial region; a seventh lens 7 having a negative optical power, an object side surface S15 of the seventh lens 7 being concave at a paraxial region, an image side surface S16 of the seventh lens 7 being concave at a paraxial region; an eighth lens 8 having a negative optical power, an object-side surface S17 of the eighth lens 8 being convex at a paraxial region, an image-side surface S18 of the eighth lens 8 being concave at a paraxial region; a ninth lens element 9 having positive optical power, an object-side surface S19 of the ninth lens element 9 being convex at a paraxial region, and an image-side surface S20 of the ninth lens element 9 being concave at a paraxial region.

In addition, the object-side surface S2 of the first lens element 1 is concave at the circumference, and the image-side surface S3 of the first lens element 1 is convex at the circumference; the object-side surface S4 of the second lens element 2 is concave at the circumference, and the image-side surface S5 of the second lens element 2 is convex at the circumference; the object side surface S6 of the third lens element 3 is concave at the circumference, and the image side surface S7 of the third lens element 3 is concave at the circumference; the object-side surface S8 of the fourth lens element 4 is convex at the circumference, and the image-side surface S9 of the fourth lens element 4 is convex at the circumference; the object-side surface S11 of the fifth lens element 5 is concave at the circumference, and the image-side surface S12 of the fifth lens element 5 is convex at the circumference; the object-side surface S13 of the sixth lens element 6 is convex at its circumference, and the image-side surface S14 of the sixth lens element 6 is concave at its circumference; the object-side surface S15 of the seventh lens element 7 is convex at the circumference, and the image-side surface S16 of the seventh lens element 7 is convex at the circumference; the object-side surface S17 of the eighth lens element 8 is concave at the circumference, and the image-side surface S18 of the eighth lens element 8 is convex at the circumference; the object-side surface S19 of the ninth lens element 9 is convex at its circumference, and the image-side surface S20 of the ninth lens element 9 is convex at its circumference.

As can be seen from the aberration diagrams in fig. 12, the longitudinal spherical aberration, curvature of field, and distortion of the optical system are well controlled, so that the optical system of this embodiment has good imaging quality. In the sixth embodiment, the effective focal length of the optical imaging system is 7.28mm for EFL, 48.69 ° for the maximum field angle FOV, 2.21 for f-number FNO, and 7.14mm for total TTL.

The reference wavelength of the focal length of the lens of the sixth embodiment is 555nm, the reference wavelength of the refractive index and the abbe number is 587.56nm, and the numerical units of the radius Y, the thickness and the focal length are all millimeters (mm). And the optical imaging system in the sixth embodiment satisfies the conditions of the following table.

TABLE 11

Table 12 below embodies the aspherical coefficients of the respective lens surfaces of table 11, where K is a conic coefficient and Ai is a coefficient corresponding to the i-th order high-order term in the aspherical surface type formula.

The above embodiments 1 to 6 satisfy the relational expressions described in table 13:

conditions/examples	1	2	3	4	5	6
							6<f2/(r22-r21)<14.5	10.976	11.572	9.107	6.458	7.014	14.057
15<f7/sag72<120	54.359	50.383	26.304	116.770	19.210	25.234
							15<r81/\|sag81\|<135	123.71	122.90	47.62	60.51	21.97	131.17
EFL/TTL>1	1.02	1.02	1.01	1.02	1.05	1.02
							f1/sd11<4.2	3.96	3.94	3.81	4.10	4.11	3.96
0.32<BFL/sd92<0.4	0.36	0.34	0.37	0.36	0.38	0.36
							IMGH*2/TTL>0.93	0.937	0.937	0.938	0.939	0.964	0.938
tan(FOV/2)/ct19>0.12mm^-1	0.13	0.12	0.13	0.13	0.16	0.14
							1.3<aet14/at14<1.75	1.63	1.71	1.43	1.44	1.42	1.35

It will be apparent to those skilled in the art that various changes and modifications may be made in the embodiments of the present invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. An optical imaging system, comprising nine lenses, in order from an object side to an image side:

a ninth lens having a power, an object-side surface of the ninth lens being convex at a paraxial region and an image-side surface of the ninth lens being concave at a paraxial region;

the optical imaging system satisfies the following conditional expression:

EFL/TTL>1；

wherein, EFL is the effective focal length of the optical imaging system, and TTL is the distance from the object side surface of the first lens to the imaging surface of the optical system on the optical axis.

2. The optical imaging system of claim 1, wherein the optical imaging system satisfies the following conditional expression:

6<f2/(r22-r21)<14.5；

wherein f2 is the second lens effective focal length; r22 is the radius of curvature of the image-side surface of the second lens at the optical axis; r21 is the radius of curvature of the object-side surface of the second lens at the optical axis.

3. The optical imaging system of claim 1, wherein the optical imaging system satisfies the following conditional expression:

15<f7/sag72<120；

4. The optical imaging system of claim 1, wherein the optical imaging system satisfies the following conditional expression:

15<r81/|sag81|<135；

5. The optical imaging system of claim 1, wherein the optical imaging system satisfies the following conditional expression:

f1/sd11<4.2；

wherein f1 is the effective focal length of the first lens; sd11 is the maximum effective half aperture of the object-side surface of the first lens.

6. The optical imaging system of claim 1, wherein the optical imaging system satisfies the following conditional expression:

0.32<BFL/sd92<0.4；

the BFL is the minimum distance from the image side surface of the ninth lens to the imaging surface of the optical imaging system in the optical axis direction; sd92 is the maximum effective half aperture of the image side surface of the ninth lens.

7. The optical imaging system of claim 1, wherein the optical imaging system satisfies the following conditional expression:

IMGH*2/TTL>0.93；

8. The optical imaging system of claim 1, wherein the optical imaging system satisfies the following conditional expression:

tan(FOV/2)/ct19>0.12mm^-1；

9. The optical imaging system of claim 1, wherein the optical imaging system satisfies the following conditional expression:

1.3<aet14/at14<1.75；

10. An image capturing module, comprising: the optical imaging system of any one of claims 1 to 9.

11. An electronic device, comprising: the image capturing module of claim 10, and a housing on which the image capturing module is mounted.