CN215494317U

CN215494317U - Optical system, image capturing module and electronic equipment

Info

Publication number: CN215494317U
Application number: CN202121060549.1U
Authority: CN
Inventors: 徐标; 李明
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2021-05-18
Filing date: 2021-05-18
Publication date: 2022-01-11
Anticipated expiration: 2031-05-18

Abstract

The utility model relates to an optical system, an image capturing module and an electronic device. The optical system includes: a first lens element with positive refractive power having a convex object-side surface and a concave image-side surface; a second lens element with negative refractive power having a convex object-side surface and a concave image-side surface; a third lens element with refractive power having a convex object-side surface at paraxial region; a fourth lens element with refractive power having a convex object-side surface and a concave image-side surface; a fifth lens element with refractive power having a concave object-side surface at paraxial region and a convex image-side surface at paraxial region; a sixth lens element with refractive power; a seventh lens element with refractive power; an eighth lens element with negative refractive power having a concave image-side surface at paraxial region; the optical system satisfies: f tan (HFOV) is less than or equal to 7.2mm and less than or equal to 7.4 mm. The optical system has the characteristics of large image surface and good imaging quality.

Description

Optical system, image capturing module and electronic equipment

Technical Field

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

Background

Along with the rapid development of the camera shooting technology, more and more electronic equipment such as smart phones, tablet computers and electronic readers are provided with optical systems to achieve the camera shooting function, so that the imaging quality requirements of the market on the electronic equipment are higher and higher to meet the requirements of users, and high-quality imaging can bring high-picture-quality shooting experience to the users. However, the imaging quality of the current optical system still needs to be improved.

SUMMERY OF THE UTILITY MODEL

Accordingly, there is a need for an optical system, an image capturing module and an electronic device to improve the imaging quality of the optical system.

An optical system includes, 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 and a concave image-side surface;

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

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

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

a sixth lens element with refractive power;

a seventh lens element with refractive power;

an eighth 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:

7.2mm≤f*tan(HFOV)≤7.4mm；

wherein f is an effective focal length of the optical system, and the HFOV is half of a maximum field angle of the optical system.

In the optical system, the first lens has positive refractive power, so that the total length of the optical system is favorably shortened, and the miniaturization design is realized. The second lens element has negative refractive power, which is beneficial to correcting aberration generated by the first lens element and improving imaging quality. The first lens and the second lens are matched, so that the on-axis spherical aberration of the optical system can be corrected, and the imaging quality is improved. The object side surfaces of the first lens and the second lens are convex surfaces at the lower beam axis, and the image side surfaces of the first lens and the second lens are concave surfaces at the lower beam axis, so that light rays in the optical system can be converged, the total length of the optical system can be shortened, and the imaging quality of the optical system can be improved. The object side surface of the third lens is a convex surface at a position near the optical axis, which is beneficial to converging light rays, thereby being beneficial to shortening the total length of the optical system. The fourth lens and the fifth lens are meniscus lenses, which are beneficial to correcting astigmatism, curvature of field and distortion of the optical system. The fifth lens element, the sixth lens element and the seventh lens element with refractive power are arranged to correct coma aberration of the optical system. The eighth lens element with negative refractive power can correct curvature of field of the optical system. The image side surface of the eighth lens element is concave at a paraxial region, which is beneficial to reducing the sensitivity of the optical system and facilitating the engineering manufacture of the optical system.

When the condition formula is met, the optical system can realize large image surface characteristics, so that the optical system can be matched with a photosensitive element with a larger size, has the characteristics of high pixel and high definition, and improves the imaging quality of the optical system.

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

1.2≤TTL/ImgH≤1.3；

wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an image plane of the optical system, that is, a total optical length of the optical system, and ImgH is a half of an image height corresponding to a maximum field angle of the optical system. When the above conditional expressions are satisfied, it is advantageous to shorten the total length of the optical system, thereby facilitating the realization of a miniaturized design.

1.0≤CT3/ET3≤1.7；

wherein CT3 is the thickness of the third lens element along the optical axis, and ET3 is the distance from the maximum effective aperture on the object side of the third lens element to the maximum effective aperture on the image side of the third lens element along the optical axis, i.e. the thickness of the edge of the third lens element. When the conditional expression is met, the surface shape of the third lens can be reasonably configured, so that the surface shape of the third lens cannot be too gentle or excessively bent, the processing and forming of the third lens are facilitated, and the forming yield is improved; meanwhile, the surface type of the third lens is reasonably configured, so that the surface type of the third lens cannot be too gentle or excessively bent, the field curvature of the optical system can be better corrected by the third lens, and the imaging quality of the optical system is improved.

1.5≤|R7+R8|/|R7-R8|≤8.0；

wherein R7 is a radius of curvature of an object-side surface of the fourth lens element at an optical axis, and R8 is a radius of curvature of an image-side surface of the fourth lens element at the optical axis. When the conditional expressions are met, the thickness ratio of the center to the edge of the fourth lens can be reasonably configured, so that the surface shape of the fourth lens cannot be too gentle or excessively bent, the tolerance sensitivity of the fourth lens is favorably reduced, and the forming yield is improved; meanwhile, the fourth lens is favorable for balancing the high-grade coma aberration of the optical system better, and the imaging quality of the optical system is improved.

0.2≤|f8/(f2+f3)|≤5.2；

wherein f8 is the effective focal length of the eighth lens, f2 is the effective focal length of the second lens, and f3 is the effective focal length of the third lens. When the conditional expressions are satisfied, the ratio of the refractive power of the eighth lens element to the sum of the refractive powers of the second lens element and the third lens element can be reasonably configured, so that the spherical aberration contribution degrees of the second lens element, the third lens element and the eighth lens element in the optical system can be reasonably distributed, and the imaging quality of the on-axis area of the optical system can be improved.

0.9≤f1/f≤1.1；

wherein f1 is the effective focal length of the first lens. When the conditional expressions are met, the ratio of the effective focal length of the first lens and the effective focal length of the optical system can be reasonably configured, so that the refractive power of the first lens cannot be too strong, the high-grade spherical aberration of the optical system can be corrected, and the imaging quality of the optical system is improved.

1.0≤|SAG61/CT6|≤2.0；

the SAG61 is a distance from an intersection point of an object side surface of the sixth lens and an optical axis to a maximum effective aperture of the object side surface of the sixth lens in the optical axis direction, wherein when the maximum effective aperture of the object side surface of the sixth lens is located on an image side of the intersection point of the object side surface of the sixth lens and the optical axis, a value of the SAG61 is positive, when the maximum effective aperture of the object side surface of the sixth lens is located on an object side of the intersection point of the object side surface of the sixth lens and the optical axis, a value of the SAG61 is negative, and the CT6 is a thickness of the sixth lens on the optical axis. When the conditional expressions are met, the surface type of the sixth lens can be reasonably configured, so that the surface type of the sixth lens cannot be too gentle or excessively bent, the tolerance sensitivity of the sixth lens is favorably reduced, the sixth lens is favorably machined and formed, and the forming yield is improved.

0.1≤D6/CT7≤1.0；

wherein D6 is an axial distance between an image-side surface of the sixth lens element and an object-side surface of the seventh lens element, and CT7 is an axial thickness of the seventh lens element. When the conditional expression is satisfied, the ratio of the air interval on the optical axis between the sixth lens and the seventh lens and the central thickness of the seventh lens can be reasonably configured, which is beneficial to the sixth lens and the seventh lens to better correct the high-order aberration of the optical system; meanwhile, the field curvature adjustment in engineering manufacturing is facilitated, and the imaging quality of the optical system is further improved. Below the lower limit of the above conditional expression, it is difficult to effectively balance the high-order aberrations of the optical system. Exceeding the upper limit of the above conditional expressions, the chief ray angle of the optical system is difficult to match with the chief ray angle of the photosensitive element, which is not favorable for improving the imaging quality of the optical system.

0.01≤R4/R5≤0.1；

wherein R4 is a curvature radius of the image side surface of the second lens at the optical axis, and R5 is a curvature radius of the object side surface of the third lens at the optical axis. When the conditional expressions are met, the ratio of the curvature radius of the image side surface of the second lens and the curvature radius of the object side surface of the third lens at the optical axis can be reasonably configured, so that the aberration of the optical system can be balanced more effectively by the second lens and the third lens, the sensitivity of the optical system is reduced, and the imaging quality of the optical system is improved. Below the lower limit of the above conditional expression, the image-side surface of the second lens is too curved, which results in too much sensitivity of the optical system and is not favorable for engineering manufacture. Exceeding the upper limit of the above conditional expression, the object-side surface of the third lens is too curved, which is not favorable for correcting the field curvature of the optical system, and is not favorable for improving the imaging quality of the optical system.

1.1≤TTL/f≤1.5；

wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an image plane of the optical system. When the conditional expressions are satisfied, the total length of the optical system is favorably shortened, and the field angle of the optical system is not too large, so that the optical system is prevented from generating serious aberration. When the optical total length of the optical system is too short below the lower limit of the above conditional expression, the sensitivity of the optical system is increased, which is not favorable for correcting the aberration of the optical system, and the field angle of the optical system is easily too small to meet the scene shooting requirement. Above the above conditional expressions, the total optical length of the optical system is too long, which is not favorable for realizing the miniaturization design, and the light of the marginal field of view is difficult to image in the effective pixel area of the imaging surface, which easily causes incomplete imaging information.

An image capturing module includes a photosensitive element and the optical system of any of the above embodiments, wherein the photosensitive element is disposed at an image side of the optical system. The optical system is adopted in the image capturing module, and can realize large image surface characteristics, thereby being beneficial to improving the imaging quality of the image capturing module.

An electronic device comprises a shell and the image capturing module, wherein the image capturing module is arranged on the shell. Adopt above-mentioned getting for instance module among the electronic equipment, be favorable to promoting electronic equipment's imaging quality.

Drawings

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

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

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

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

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

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

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

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

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

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

FIG. 11 is a schematic structural diagram of an optical system according to a sixth embodiment of the present application;

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

fig. 13 is a schematic view of an image capturing module according to an embodiment of the present application;

fig. 14 is a schematic diagram of an electronic device in an embodiment of the present application.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the utility model and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the utility model.

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

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood by those skilled in the art according to specific situations.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" 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 as used herein are for illustrative purposes only and do not denote a unique embodiment.

Referring to fig. 1, in some embodiments of the present application, an 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, and an eighth lens L8. Specifically, the first lens L1 includes an object-side surface S1 and an image-side surface S2, the second lens L2 includes an object-side surface S3 and an image-side surface S4, the third lens L3 includes an object-side surface S5 and an image-side surface S6, the fourth lens L4 includes an object-side surface S7 and an image-side surface S8, the fifth lens L5 includes an object-side surface S9 and an image-side surface S10, the sixth lens L6 includes an object-side surface S11 and an image-side surface S12, the seventh lens L7 includes an object-side surface S13 and an image-side surface S14, and the eighth lens L8 includes an object-side surface S15 and an image-side surface S16.

The first lens element L1 has positive refractive power, which is beneficial to shortening the total length of the optical system 100 and realizing a compact design. The object-side surface S1 of the first lens element L1 is convex at the paraxial region 110, and the image-side surface S2 is concave at the paraxial region 110, which is favorable for converging light rays in the optical system 100, thereby being favorable for shortening the total length of the optical system 100 and improving the imaging quality of the optical system 100. The second lens element L2 with negative refractive power is favorable for correcting the aberration generated by the first lens element L1, thereby improving the imaging quality. The object-side surface S3 of the second lens element L2 is convex at the paraxial region 110, and the image-side surface S4 is concave at the paraxial region 110, which is favorable for converging light rays in the optical system 100, thereby being favorable for shortening the total length of the optical system 100 and improving the imaging quality of the optical system 100. The first lens L1 and the second lens L2 are matched to facilitate the correction of the on-axis spherical aberration of the optical system 100, thereby improving the imaging quality. The object-side surface S5 of the third lens element L3 is convex in a direction near the optical axis 110, which is advantageous for converging light rays, thereby being advantageous for shortening the total length of the optical system 100. The fourth lens element L4 has refractive power. The fifth lens element L5, the sixth lens element L6 and the seventh lens element L7 all have refractive power, which is favorable for correcting coma aberration of the optical system 100. The object-side surface S7 of the fourth lens element L4 is convex at the paraxial region 110, and the image-side surface S8 is concave at the paraxial region 110. The object-side surface S9 of the fifth lens element L5 is concave at the paraxial region 110, and the image-side surface S10 is convex at the paraxial region 110. The fourth lens element L4 and the fifth lens element L5 are meniscus lenses, which are advantageous for correcting astigmatism, curvature of field and distortion of the optical system 100. The eighth lens element L8 has negative refractive power, which is favorable for correcting the curvature of field of the optical system 100. The image-side surface S16 of the eighth lens element L8 is concave at a position near the optical axis 110, which is favorable for reducing the sensitivity of the optical system 100 and is favorable for the engineering manufacture of the optical system 100.

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 or on the object side S1 of the first lens L1. In some embodiments, the optical system 100 further includes an infrared filter L9 disposed on the image side of the eighth lens L8, and the infrared filter L9 includes an object-side surface S17 and an image-side surface S18. Furthermore, the optical system 100 further includes an image plane S19 located on the image side of the eighth lens L8, the image plane S19 is an imaging plane of the optical system 100, and incident light is 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 and the eighth lens L8 and can be imaged on the image plane S19. It should be noted that the infrared filter L9 may be an infrared cut filter, and is used for filtering the interference light and preventing the interference light from reaching the image plane S19 of the optical system 100 to affect the normal imaging.

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

In some embodiments, each lens in the optical system 100 may be made of glass or plastic. The lens made of plastic material can reduce the weight of the optical system 100 and the production cost, and the light and thin design of the optical system 100 can be realized by matching with the small size of the optical system 100. The glass lens provides the optical system 100 with excellent optical performance and high temperature resistance. It should be noted that the material of each lens in the optical system 100 may be any combination of glass and plastic, and is not necessarily both glass and plastic.

It is to be noted that the first lens L1 does not mean that there is only one lens, and in some embodiments, there may be two or more lenses in the first lens L1, and the two or more lenses can form a cemented lens, and a surface of the cemented lens closest to the object side can be regarded as the object side surface S1, and a surface of the cemented lens closest to the image side can be regarded as the image side surface S2. Alternatively, although no cemented lens is formed between the lenses of the first lens L1, the distance between the lenses is relatively fixed, and in this case, the object-side surface of the lens closest to the object side is the object-side surface S1, and the image-side surface of the lens closest to the image side is the image-side surface S2. In addition, the number of lenses in the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, or the eighth lens L8 in some embodiments may be greater than or equal to two, and a cemented lens may be formed between any two adjacent lenses, or a non-cemented lens may be used.

Further, in some embodiments, the optical system 100 satisfies the conditional expression: f tan (HFOV) is less than or equal to 7.2mm and less than or equal to 7.4 mm; where f is the effective focal length of the optical system 100 and the HFOV is half the maximum field angle of the optical system 100. Specifically, f tan (hfov) may be: 7.203, 7.208, 7.210, 7.214, 7.219, 7.225, 7.227, 7.236, 7.238, or 7.243, the numerical units being mm. When the above conditional expressions are satisfied, the optical system 100 can realize a large image plane characteristic, so that a larger-sized photosensitive element can be matched, the optical system 100 has the characteristics of high pixel and high definition, and the imaging quality of the optical system 100 is improved.

In some embodiments, the optical system 100 satisfies the conditional expression: TTL/ImgH is more than or equal to 1.2 and less than or equal to 1.3; wherein, TTL is a distance from the object-side surface S1 of the first lens element L1 to the image plane of the optical system 100 on the optical axis 110, and ImgH is half of the image height corresponding to the maximum field angle of the optical system 100. Specifically, TTL/ImgH may be: 1.212, 1.213, 1.215, 1.217, 1.218, 1.220, 1.221, 1.223, 1.224, or 1.225. When the above conditional expressions are satisfied, it is advantageous to shorten the total length of the optical system 100, thereby contributing to the realization of a miniaturized design.

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, the effective pixel region on the imaging plane of the optical system 100 has a horizontal direction and a diagonal direction, and the HFOV may be understood as half of the maximum field angle of the optical system 100 in the diagonal direction, and the ImgH may be understood as half of the length of the effective pixel region on the imaging plane of the optical system 100 in the diagonal direction.

In some embodiments, the optical system 100 satisfies the conditional expression: FNO is not less than 1.8 and not more than 1.9, wherein FNO is the f-number of the optical system 100. Specifically, FNO may be: 1.87 or 1.88. Satisfying the above conditional expressions, the optical system 100 can realize a large aperture characteristic, so that the optical system 100 has a sufficient light incident amount, which is beneficial to making the image shot by the optical system 100 clearer; meanwhile, the imaging quality of the optical system 100 in a low-light environment can be improved.

In some embodiments, the optical system 100 satisfies the conditional expression: CT3/ET3 is more than or equal to 1.0 and less than or equal to 1.7; CT3 is the thickness of the third lens element L3 along the optical axis 110, and ET3 is the distance from the maximum effective aperture of the object-side surface S5 of the third lens element L3 to the maximum effective aperture of the image-side surface S6 of the third lens element L3 along the optical axis 110. Specifically, CT3/ET3 may be: 1.637, 1.639, 1.642, 1.653, 1.655, 1.660, 1.668, 1.673, 1.677 or 1.689. When the conditional expressions are satisfied, the surface shape of the third lens L3 can be reasonably configured, so that the surface shape of the third lens L3 is not excessively gentle or excessively bent, the processing and molding of the third lens L3 are facilitated, and the molding yield is improved; meanwhile, the surface type of the third lens L3 is reasonably configured, so that the surface type of the third lens L3 is not too gentle or excessively curved, which is beneficial for the third lens L3 to better correct the curvature of field of the optical system 100, and improves the imaging quality of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: the absolute value of R7+ R8/| R7-R8| is more than or equal to 1.5 and less than or equal to 8.0; wherein R7 is a radius of curvature of the object-side surface S7 of the fourth lens element L4 along the optical axis 110, and R8 is a radius of curvature of the image-side surface S8 of the fourth lens element L4 along the optical axis 110. Specifically, | R7+ R8|/| R7-R8| may be: 1.807, 2.105, 2.654, 3.456, 3.397, 4.284, 5.301, 5.596, 6.372, or 7.644. When the conditional expressions are satisfied, the thickness ratio of the center to the edge of the fourth lens L4 can be reasonably configured, so that the surface shape of the fourth lens L4 is not too gentle or excessively bent, the tolerance sensitivity of the fourth lens L4 is reduced, and the molding yield is improved; meanwhile, the fourth lens L4 is also beneficial to better balance the high-level coma aberration of the optical system 100, and the imaging quality of the optical system 100 is improved.

In some embodiments, the optical system 100 satisfies the conditional expression: | f8/(f2+ f3) | is not less than 0.2 and not more than 5.2; wherein f8 is the effective focal length of the eighth lens L8, f2 is the effective focal length of the second lens L2, and f3 is the effective focal length of the third lens L3. Specifically, | f8/(f2+ f3) | may be: 0.206, 0.217, 0.229, 0.364, 0.501, 0.663, 0.701, 0.778, 1.364 or 5.148. When the above conditional expressions are satisfied, the ratio of the refractive power of the eighth lens element L8 to the sum of the refractive powers of the second lens element L2 and the third lens element L3 can be reasonably configured, so that the spherical aberration contributions of the second lens element L2, the third lens element L3 and the eighth lens element L8 in the optical system 100 can be reasonably distributed, and the imaging quality of the on-axis region of the optical system 100 can be further improved.

In some embodiments, the optical system 100 satisfies the conditional expression: f1/f is more than or equal to 0.9 and less than or equal to 1.1; where f1 is the effective focal length of the first lens L1. Specifically, f1/f may be: 0.981, 0.983, 0.985, 0.986, 0.990, 0.992, 0.995, 0.999, 1.012 or 1.022. When the above conditional expressions are satisfied, the ratio of the effective focal lengths of the first lens element L1 and the optical system 100 can be reasonably configured, so that the refractive power of the first lens element L1 is not too strong, which is beneficial to correcting the high-order spherical aberration of the optical system 100 and improving the imaging quality of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: the absolute value of SAG61/CT6 is more than or equal to 1.0 and less than or equal to 2.0; the SAG61 is a distance from an intersection point of the object-side surface S11 of the sixth lens L6 and the optical axis 110 to a maximum effective aperture of the object-side surface S11 of the sixth lens L6 in the direction of the optical axis 110, and the CT6 is a thickness of the sixth lens L6 on the optical axis 110. Specifically, | SAG61/CT6| can be: 1.051, 1.102, 1.235, 1.289, 1.355, 1.436, 1.628, 1.784, 1.883 or 1.929. When the conditional expressions are satisfied, the surface shape of the sixth lens L6 can be reasonably configured, so that the surface shape of the sixth lens L6 is not too gentle or excessively curved, the tolerance sensitivity of the sixth lens L6 is favorably reduced, the machining and forming of the sixth lens L6 are favorably realized, and the forming yield is improved.

In some embodiments, the optical system 100 satisfies the conditional expression: D6/CT7 is more than or equal to 0.1 and less than or equal to 1.0; wherein D6 is the distance between the image-side surface S12 of the sixth lens element L6 and the object-side surface S13 of the seventh lens element L7 on the optical axis 110, and CT7 is the thickness of the seventh lens element L7 on the optical axis 110. Specifically, D6/CT7 may be: 0.203, 0.245, 0.267, 0.289, 0.301, 0.339, 0.412, 0.453, 0.477, or 0.496. When the above conditional expressions are satisfied, the ratio of the air space on the optical axis 110 between the sixth lens L6 and the seventh lens L7 and the central thickness of the seventh lens L7 can be reasonably configured, which is beneficial for the sixth lens L6 and the seventh lens L7 to better correct the high-level aberration of the optical system 100; meanwhile, the field curvature adjustment in engineering manufacturing is facilitated, and the imaging quality of the optical system 100 is further improved. Below the lower limit of the above conditional expression, it is difficult to effectively balance the high-order aberrations of the optical system 100. Above the upper limit of the above conditional expression, the chief ray angle of the optical system 100 is difficult to match with the chief ray angle of the photosensitive element, which is not favorable for improving the imaging quality of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: R4/R5 is more than or equal to 0.01 and less than or equal to 0.1; wherein R4 is the radius of curvature of the image-side surface S4 of the second lens element L2 along the optical axis 110, and R5 is the radius of curvature of the object-side surface S5 of the third lens element L3 along the optical axis 110. Specifically, R4/R5 may be: 0.029, 0.031, 0.032, 0.039, 0.045, 0.061, 0.063, 0.070, 0.078, or 0.088. When the above conditional expressions are satisfied, the ratio of the curvature radii of the image-side surface S4 of the second lens element L2 and the object-side surface S5 of the third lens element L3 at the optical axis 110 can be reasonably configured, which is beneficial to more effectively balance the aberration of the optical system 100 for the whole of the second lens element L2 and the third lens element L3, and reduce the sensitivity of the optical system 100, thereby improving the imaging quality of the optical system 100. Below the lower limit of the conditional expression, the image-side surface S4 of the second lens L2 is too curved, which results in too much sensitivity of the optical system 100 and is not favorable for engineering. Exceeding the upper limit of the above conditional expression, the object-side surface S5 of the third lens L3 is too curved to correct the curvature of field of the optical system 100, and thus the image quality of the optical system 100 is not improved.

In some embodiments, the optical system 100 satisfies the conditional expression: TTL/f is more than or equal to 1.1 and less than or equal to 1.5; wherein, TTL is a distance from the object-side surface S1 of the first lens element L1 to the image plane of the optical system 100 on the optical axis 110. Specifically, TTL/f may be: 1.185, 1.187, 1.188, 1.195, 1.201, 1.203, 1.208, 1.210, 1.211, or 1.214. Satisfying the above conditional expressions is advantageous in shortening the total system length of the optical system 100 and preventing the field angle of the optical system 100 from becoming too large, thereby preventing the optical system 100 from generating severe aberration. Below the lower limit of the above conditional expression, the total optical length of the optical system 100 is too short, which increases the sensitivity of the optical system 100, is not favorable for correcting the aberration of the optical system 100, and tends to make the field angle of the optical system 100 too small to meet the scene shooting requirement. Exceeding the above conditional expressions, the optical system 100 has an excessively long total optical length, which is not favorable for realizing a compact design, and the light of the peripheral field of view is difficult to be imaged in the effective pixel area of the imaging plane, which is likely to cause incomplete imaging information.

The reference wavelengths of the above effective focal length values are all 555 nm.

Based on the above description of the embodiments, more specific embodiments and drawings are set forth below for detailed description.

First embodiment

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

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

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

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

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

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

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

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

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

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

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

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

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

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

The object-side surface and the image-side surface 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, and the eighth lens L8 are aspheric.

It should be noted that, in the present application, when a surface of the lens is described as being convex at a position near the optical axis 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 a surface of a lens is described as concave at the circumference, it is understood that the surface is concave near the region of maximum effective radius. For example, when the surface is convex at a paraxial region 110 and also convex at a peripheral region, the shape of the surface from the center (the intersection of the surface with the optical axis 110) to the edge direction may be purely convex; or a convex shape at the center is firstly transited to a concave shape, and then becomes a convex shape near the maximum effective radius. Here, only examples are made to illustrate the relationship at the optical axis 110 and the circumference, and various shape structures (concave-convex relationship) of the surface are not fully embodied, but other cases can be derived from the above examples.

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 and the eighth lens L8 are all made of plastic.

Further, the optical system 100 satisfies the conditional expression: f tan (hfov) ═ 7.243 mm; where f is the effective focal length of the optical system 100 and the HFOV is half the maximum field angle of the optical system 100. When the above conditional expressions are satisfied, the optical system 100 can realize a large image plane characteristic, so that a larger-sized photosensitive element can be matched, the optical system 100 has the characteristics of high pixel and high definition, and the imaging quality of the optical system 100 is improved.

The optical system 100 satisfies the conditional expression: TTL/ImgH is 1.225; wherein, TTL is a distance from the object-side surface S1 of the first lens element L1 to the image plane of the optical system 100 on the optical axis 110, and ImgH is half of the image height corresponding to the maximum field angle of the optical system 100. When the above conditional expressions are satisfied, it is advantageous to shorten the total length of the optical system 100, thereby contributing to the realization of a miniaturized design.

The optical system 100 satisfies the conditional expression: FNO is 1.87, where FNO is the f-number of the optical system 100. Satisfying the above conditional expressions, the optical system 100 can realize a large aperture characteristic, so that the optical system 100 has a sufficient light incident amount, which is beneficial to making the image shot by the optical system 100 clearer; meanwhile, the imaging quality of the optical system 100 in a low-light environment can be improved.

The optical system 100 satisfies the conditional expression: CT3/ET3 ═ 1.637; CT3 is the thickness of the third lens element L3 along the optical axis 110, and ET3 is the distance from the maximum effective aperture of the object-side surface S5 of the third lens element L3 to the maximum effective aperture of the image-side surface S6 of the third lens element L3 along the optical axis 110. When the conditional expressions are satisfied, the surface shape of the third lens L3 can be reasonably configured, so that the surface shape of the third lens L3 is not excessively gentle or excessively bent, the processing and molding of the third lens L3 are facilitated, and the molding yield is improved; meanwhile, the surface type of the third lens L3 is reasonably configured, so that the surface type of the third lens L3 is not too gentle or excessively curved, which is beneficial for the third lens L3 to better correct the curvature of field of the optical system 100, and improves the imaging quality of the optical system 100.

The optical system 100 satisfies the conditional expression: r7+ R8/| R7-R8| ═ 3.101; wherein R7 is a radius of curvature of the object-side surface S7 of the fourth lens element L4 along the optical axis 110, and R8 is a radius of curvature of the image-side surface S8 of the fourth lens element L4 along the optical axis 110. When the conditional expressions are satisfied, the thickness ratio of the center to the edge of the fourth lens L4 can be reasonably configured, so that the surface shape of the fourth lens L4 is not too gentle or excessively bent, the tolerance sensitivity of the fourth lens L4 is reduced, and the molding yield is improved; meanwhile, the fourth lens L4 is also beneficial to better balance the high-level coma aberration of the optical system 100, and the imaging quality of the optical system 100 is improved.

The optical system 100 satisfies the conditional expression: i f8/(f2+ f3) | 0.778; wherein f8 is the effective focal length of the eighth lens L8, f2 is the effective focal length of the second lens L2, and f3 is the effective focal length of the third lens L3. When the above conditional expressions are satisfied, the ratio of the refractive power of the eighth lens element L8 to the sum of the refractive powers of the second lens element L2 and the third lens element L3 can be reasonably configured, so that the spherical aberration contributions of the second lens element L2, the third lens element L3 and the eighth lens element L8 in the optical system 100 can be reasonably distributed, and the imaging quality of the on-axis region of the optical system 100 can be further improved.

The optical system 100 satisfies the conditional expression: f1/f is 0.992; where f1 is the effective focal length of the first lens L1. When the above conditional expressions are satisfied, the ratio of the effective focal lengths of the first lens element L1 and the optical system 100 can be reasonably configured, so that the refractive power of the first lens element L1 is not too strong, which is beneficial to correcting the high-order spherical aberration of the optical system 100 and improving the imaging quality of the optical system 100.

The optical system 100 satisfies the conditional expression: 1.292 | SAG61/CT6 |; the SAG61 is a distance from an intersection point of the object-side surface S11 of the sixth lens L6 and the optical axis 110 to a maximum effective aperture of the object-side surface S11 of the sixth lens L6 in the direction of the optical axis 110, and the CT6 is a thickness of the sixth lens L6 on the optical axis 110. When the conditional expressions are satisfied, the surface shape of the sixth lens L6 can be reasonably configured, so that the surface shape of the sixth lens L6 is not too gentle or excessively curved, the tolerance sensitivity of the sixth lens L6 is favorably reduced, the machining and forming of the sixth lens L6 are favorably realized, and the forming yield is improved.

The optical system 100 satisfies the conditional expression: D6/CT7 is 0.242; wherein D6 is the distance between the image-side surface S12 of the sixth lens element L6 and the object-side surface S13 of the seventh lens element L7 on the optical axis 110, and CT7 is the thickness of the seventh lens element L7 on the optical axis 110. When the above conditional expressions are satisfied, the ratio of the air space on the optical axis 110 between the sixth lens L6 and the seventh lens L7 and the central thickness of the seventh lens L7 can be reasonably configured, which is beneficial for the sixth lens L6 and the seventh lens L7 to better correct the high-level aberration of the optical system 100; meanwhile, the field curvature adjustment in engineering manufacturing is facilitated, and the imaging quality of the optical system 100 is further improved. Below the lower limit of the above conditional expression, it is difficult to effectively balance the high-order aberrations of the optical system 100. Above the upper limit of the above conditional expression, the chief ray angle of the optical system 100 is difficult to match with the chief ray angle of the photosensitive element, which is not favorable for improving the imaging quality of the optical system 100.

The optical system 100 satisfies the conditional expression: R4/R5 ═ 0.034; wherein R4 is the radius of curvature of the image-side surface S4 of the second lens element L2 along the optical axis 110, and R5 is the radius of curvature of the object-side surface S5 of the third lens element L3 along the optical axis 110. When the above conditional expressions are satisfied, the ratio of the curvature radii of the image-side surface S4 of the second lens element L2 and the object-side surface S5 of the third lens element L3 at the optical axis 110 can be reasonably configured, which is beneficial to more effectively balance the aberration of the optical system 100 for the whole of the second lens element L2 and the third lens element L3, and reduce the sensitivity of the optical system 100, thereby improving the imaging quality of the optical system 100. Below the lower limit of the above conditional expression, the sensitivity of the optical system 100 is too high, which is not favorable for engineering manufacturing.

The optical system 100 satisfies the conditional expression: TTL/f is 1.200; wherein, TTL is a distance from the object-side surface S1 of the first lens element L1 to the image plane of the optical system 100 on the optical axis 110. Satisfying the above conditional expressions is advantageous in shortening the total system length of the optical system 100 and preventing the field angle of the optical system 100 from becoming too large, thereby preventing the optical system 100 from generating severe aberration.

In addition, the parameters of the optical system 100 are given in table 1. Among them, the image plane S19 in table 1 may be understood as an imaging plane of the optical system 100. The elements from the object plane (not shown) to the image plane S19 are sequentially arranged in the order of the elements from top to bottom in table 1. The Y radius in table 1 is the radius of curvature of the object-side or image-side surface at the optical axis 110 for the corresponding surface number. Surface numbers S1 and S2 denote an object-side surface S1 and an image-side surface S2 of the first lens L1, respectively, that is, in the same lens, a surface with a smaller surface number is an object-side surface, and a surface with a larger surface number is an image-side surface. The first numerical value in the "thickness" parameter column of the first lens element L1 is the thickness of the lens element along the optical axis 110, and the second numerical value is the distance between the image-side surface and the rear surface of the lens element along the image-side direction along the optical axis 110.

Note that, in this embodiment and the following embodiments, the optical system 100 may not be provided with the infrared filter L9, but the distance from the image-side surface S16 of the eighth lens L8 to the image surface S19 is kept constant at this time.

In the first embodiment, the effective focal length f of the optical system 100 is 7.5mm, the f-number FNO is 1.87, the maximum field angle FOV is 88 °, and the total optical length TTL is 9.0 mm.

And the reference wavelength of the focal length of each lens is 555nm, the reference wavelength of the refractive index and the Abbe number is 587.56nm, and the other embodiments are also the same.

TABLE 1

Further, aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are given by table 2. Wherein, the surface numbers from S1 to S16 represent the image side or the object side S1 to S16, respectively. And K-a20 from top to bottom respectively indicate the types of aspheric coefficients, where K indicates a conic coefficient, a4 indicates a quartic aspheric coefficient, a6 indicates a sextic aspheric coefficient, A8 indicates an octal aspheric coefficient, and so on. In addition, the aspherical surface coefficient formula is as follows:

where Z is the distance from the corresponding point on the aspheric surface to the plane tangent 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 surface vertex, k is the conic coefficient, and Ai is the coefficient corresponding to the i-th high order term in the aspheric surface profile 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 converging focal points of the light rays of different wavelengths after passing through the lens. The ordinate of the longitudinal spherical aberration diagram represents the Normalized Pupil coordinate (Normalized Pupil Coordinator) from the Pupil center to the Pupil edge, and the abscissa represents the distance (in mm) of the imaging plane from the intersection of the ray with the optical axis 110. It can be known from the longitudinal spherical aberration diagram that the convergent focus deviation degrees of the light rays with different wavelengths in the first embodiment tend to be consistent, and the diffuse speckle or the chromatic halo in the imaging picture is effectively suppressed. FIG. 2 also includes a field curvature diagram (ASTIGMATIC FIELD CURVES) of optical system 100, where the S-curve represents sagittal field curvature at 555nm and the T-curve represents meridional field curvature at 555 nm. As can be seen from the figure, the curvature of field of the optical system 100 is small, the curvature of field and astigmatism of each field are well corrected, and the center and the edge of the field have clear images. Fig. 2 also includes a DISTORTION map (distorsion) of the optical system 100, and it can be seen that the image DISTORTION caused by the main beam is small and the imaging quality of the system is excellent.

Second embodiment

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

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

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

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

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

TABLE 3

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 4, and the definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

TABLE 4

According to the provided parameter information, the following data can be deduced:

f*tan(HFOV)	7.243mm	f1/f	0.982
				TTL/ImgH	1.214	\|SAG61/CT6\|	1.316
CT3/ET3	1.668	D6/CT7	0.267
				\|R7+R8\|/\|R7-R8\|	3.581	R4/R5	0.051
\|f8/(f2+f3)\|	0.610	TTL/f	1.189

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

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

TABLE 5

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 6, and the definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

TABLE 6

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

f*tan(HFOV)	7.223mm	f1/f	0.981
				TTL/ImgH	1.213	\|SAG61/CT6\|	1.324
CT3/ET3	1.665	D6/CT7	0.273
				\|R7+R8\|/\|R7-R8\|	3.895	R4/R5	0.060
\|f8/(f2+f3)\|	0.574	TTL/f	1.190

in addition, as can be seen from the aberration diagram in fig. 6, the longitudinal spherical aberration, curvature of field, and distortion of the optical system 100 are 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 the optical system 100 in the fourth embodiment, in which the optical system 100 includes, in order from an object side to an image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with negative refractive power, a sixth lens element L6 with negative refractive power, a seventh lens element L7 with positive refractive power, and an eighth lens element L8 with negative refractive power. Fig. 8 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the fourth embodiment, which is shown from left to right.

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

TABLE 7

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 8, and the definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

TABLE 8

f*tan(HFOV)	7.228mm	f1/f	0.995
				TTL/ImgH	1.212	\|SAG61/CT6\|	1.075
CT3/ET3	1.666	D6/CT7	0.256
				\|R7+R8\|/\|R7-R8\|	7.644	R4/R5	0.088
\|f8/(f2+f3)\|	0.206	TTL/f	1.199

in addition, as can be seen from the aberration diagram in fig. 8, the longitudinal spherical aberration, curvature of field, and distortion of the optical system 100 are 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 the optical system 100 in the fifth embodiment, in which the optical system 100 includes, in order from an object side to an image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with negative refractive power, a fifth lens element L5 with negative refractive power, a sixth lens element L6 with positive refractive power, a seventh lens element L7 with positive refractive power, and an eighth lens element L8 with negative refractive power. Fig. 10 is a graph showing the longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the fifth embodiment from left to right.

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

TABLE 9

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 10, and the definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

Watch 10

f*tan(HFOV)	7.203mm	f1/f	1.022
				TTL/ImgH	1.213	\|SAG61/CT6\|	1.051
CT3/ET3	1.689	D6/CT7	0.496
				\|R7+R8\|/\|R7-R8\|	2.527	R4/R5	0.029
\|f8/(f2+f3)\|	0.696	TTL/f	1.214

in addition, as can be seen from the aberration diagram in fig. 10, the longitudinal spherical aberration, curvature of field, and distortion of the optical system 100 are 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 the optical system 100 in the sixth embodiment, in which the optical system 100 includes, in order from an object side to an image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with negative refractive power, a fifth lens element L5 with positive refractive power, a sixth lens element L6 with positive refractive power, a seventh lens element L7 with negative refractive power, and an eighth lens element L8 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 definitions of the parameters can be obtained from the first embodiment, which is not described herein.

TABLE 11

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

TABLE 12

f*tan(HFOV)	7.227mm	f1/f	0.986
				TTL/ImgH	1.213	\|SAG61/CT6\|	1.929
CT3/ET3	1.684	D6/CT7	0.203
				\|R7+R8\|/\|R7-R8\|	1.807	R4/R5	0.062
\|f8/(f2+f3)\|	5.132	TTL/f	1.185

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

Referring to fig. 13, 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 light-sensing surface of the light-sensing element 210 may be regarded as the image surface S19 of the optical system 100. The image capturing module 200 may further include an infrared filter L9, and the infrared filter L9 is disposed between the image side surface S16 and the image surface S19 of the eighth lens element L8. Specifically, the photosensitive element 210 may be a Charge Coupled Device (CCD) or a Complementary Metal-Oxide Semiconductor (CMOS) Device. By adopting the optical system 100 in the image capturing module 200, the optical system 100 can realize large image plane characteristics, which is beneficial to improving the imaging quality of the image capturing module 200.

Referring to fig. 13 and 14, in some embodiments, the image capturing module 200 may be applied to an electronic device 300, the electronic device includes a housing 310, and the image capturing module 200 is disposed in the housing 310. Specifically, the electronic apparatus 300 may be, but is not limited to, a wearable device such as a mobile phone, a video phone, a smart phone, an electronic book reader, a vehicle-mounted image capturing apparatus such as a car recorder, or a smart watch. When the electronic device 300 is a smartphone, the housing 310 may be a middle frame of the electronic device 300. The image capturing module 200 is adopted in the electronic device 300, which is beneficial to improving the imaging quality of the electronic device 300.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the utility model. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.

Claims

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

a sixth lens element with refractive power;

a seventh lens element with refractive power;

and the optical system satisfies the following conditional expression:

7.2mm≤f*tan(HFOV)≤7.4mm；

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

1.2≤TTL/ImgH≤1.3；

wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an image plane of the optical system, and ImgH is half of an image height corresponding to a maximum field angle of the optical system.

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

1.0≤CT3/ET3≤1.7；

wherein CT3 is a thickness of the third lens element in an optical axis direction, and ET3 is a distance from an object-side maximum effective aperture of the third lens element to an image-side maximum effective aperture of the third lens element in the optical axis direction.

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

1.5≤|R7+R8|/|R7-R8|≤8.0；

wherein R7 is a radius of curvature of an object-side surface of the fourth lens element at an optical axis, and R8 is a radius of curvature of an image-side surface of the fourth lens element at the optical axis.

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

0.2≤|f8/(f2+f3)|≤5.2；

wherein f8 is the effective focal length of the eighth lens, f2 is the effective focal length of the second lens, and f3 is the effective focal length of the third lens.

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

0.9≤f1/f≤1.1；

wherein f1 is the effective focal length of the first lens.

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

1.0≤|SAG61/CT6|≤2.0；

SAG61 is the distance from the intersection point of the object side surface of the sixth lens and the optical axis to the maximum effective aperture of the object side surface of the sixth lens in the optical axis direction, and CT6 is the thickness of the sixth lens in the optical axis direction.

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

0.1≤D6/CT7≤1.0；

wherein D6 is an axial distance between an image-side surface of the sixth lens element and an object-side surface of the seventh lens element, and CT7 is an axial thickness of the seventh lens element.

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

0.01≤R4/R5≤0.1；

wherein R4 is a curvature radius of the image side surface of the second lens at the optical axis, and R5 is a curvature radius of the object side surface of the third lens at the optical axis.

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

1.1≤TTL/f≤1.5；

wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an image plane of the optical system.

11. An image capturing module, comprising a photosensitive element and the optical system of any one of claims 1 to 10, wherein the photosensitive element is disposed on an image side of the optical system.

12. An electronic device, comprising a housing and the image capturing module of claim 11, wherein the image capturing module is disposed on the housing.