CN112987258B

CN112987258B - Optical system, image capturing module and electronic equipment

Info

Publication number: CN112987258B
Application number: CN202110340969.3A
Authority: CN
Inventors: 徐标; 李明; 宋琦
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: 2022-08-30
Anticipated expiration: 2041-03-30
Also published as: CN112987258A

Abstract

The invention 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 refractive power having a convex object-side surface at paraxial region and a concave image-side surface at paraxial region; a third lens element with refractive power; a fourth lens element with refractive power having a concave image-side surface at paraxial region; a fifth lens element with refractive power having a concave object-side surface at paraxial region; a sixth lens element with refractive power having a concave image-side surface at paraxial region; a seventh lens element with positive refractive power; and an eighth lens element with negative refractive power having a concave image-side surface at paraxial region; and the optical system satisfies: ImgH2/(TTL FNO) is not less than 2.5mm and not more than 2.53 mm. The condition is satisfied, and the imaging quality of the optical system in a weak light environment can be improved.

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

With the rapid development of the camera shooting technology, the imaging quality requirements of users on electronic equipment such as smart phones and tablet computers are higher and higher, high-quality imaging can bring higher-quality shooting experience to the users, and the performance improvement of an optical system in the electronic equipment is one of key factors for improving the imaging quality. However, the current optical system has poor shooting effect in the low light environments such as night scenes, rainy days, starry sky, and the like, and is difficult to meet the requirement of high imaging quality.

Disclosure of Invention

Accordingly, it is desirable to provide an optical system, an image capturing module and an electronic device for solving the problem of poor shooting effect of the conventional optical system in a low light environment.

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 and a concave image-side surface;

a second 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 third lens element with refractive power;

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

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

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

a seventh lens element with positive refractive power; and

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:

2.5mm≤ImgH ² /(TTL*FNO)≤2.53mm；

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

In the optical system, the first lens element has positive refractive power, which is beneficial to shortening the total length of the optical system and meets the requirement of miniaturization design of the optical system. The object side surface of the first lens element is convex at a paraxial region, which is beneficial to enhancing the positive refractive power of the first lens element, further shortening the total length of the optical system, and simultaneously being beneficial to enabling light rays of each field of view to uniformly enter the optical system. The image side surface of the sixth lens element is concave at the paraxial region, which is advantageous for shortening the total length of the optical system. The seventh lens element with positive refractive power is favorable for improving the ability of converging light rays at the image side end of the optical system. The eighth lens element with negative refractive power is advantageous for correcting aberration generated by the optical system to shorten the total length of the system. The image side surface of the eighth lens element is concave at a paraxial region, and the principal point can be located away from the image plane of the optical system, thereby further shortening the overall length of the optical system.

The half-image height, the total optical length and the f-number of the optical system can be reasonably configured to meet the conditional expression, so that the maximum field angle of the optical system can be expanded, the optical system can acquire more scene contents, and the imaging information of the optical system is enriched; in addition, the characteristic of large aperture of the optical system is facilitated, and the light inlet quantity of the optical system is improved, so that the imaging quality of the optical system in a low-light environment is improved, the optical system has a better blurring effect, and the requirement of high imaging quality is met; in addition, the system length of the optical system is shortened, and the miniaturization design is realized.

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

the FOV is more than or equal to 82.5 degrees and less than or equal to 84 degrees. When the conditional expressions are met, the optical system has wide-angle characteristics, so that the optical system can acquire more scene contents and enrich imaging information of the optical system.

TTL is not less than 7.55mm and not more than 7.6 mm. The system length of the optical system can be shortened by satisfying the conditional expressions, and the requirement of miniaturization design is met.

FNO 1.59. Satisfying the above conditional expressions, a large aperture design of the optical system can be realized.

5.4mm≤f*tan(HFOV)≤5.5mm；

wherein f is an effective focal length of the optical system, and the HFOV is a half of a maximum field angle of the optical system. The optical system can reasonably configure the effective focal length and the maximum half field angle of the optical system, is beneficial to shortening the total length of the optical system and meets the requirement of miniaturization design; meanwhile, the deflection angle of light rays in the optical system can be reduced, so that the surface shape of each lens in the optical system can not be excessively bent or excessively gentle, and the yield of injection molding of each lens can be improved; moreover, the optical system is favorable for having large image surface characteristics, so that the optical system can be matched with a photosensitive element with a larger size, and the imaging quality of the optical system is further favorable for being improved.

TTL/ImgH is more than or equal to 1.35 and less than or equal to 1.4. The condition formula is satisfied, the total length of the optical system is favorably shortened, and the requirement of miniaturization design is satisfied. Below the lower limit of the conditional expression, the total system length of the optical system is too short and/or the half-image height is too large, so that the edge imaging is poor, and the improvement of the imaging quality of the optical system is not facilitated while the miniaturization design requirement is realized; exceeding the upper limit of the above conditional expressions is disadvantageous in the miniaturization of the optical system because the total length of the optical system is too long.

1≤|R13+R14|/|R13-R14|≤1.2；

wherein R13 is a curvature radius of an object-side surface of the seventh lens at an optical axis, and R14 is a curvature radius of an image-side surface of the seventh lens at the optical axis. The surface type of the seventh lens can be reasonably configured when the conditional expressions are met, so that the surface type of the seventh lens cannot be excessively bent or excessively gentle, the tolerance sensitivity of the seventh lens is favorably reduced, and the injection molding yield of the seventh lens is improved; meanwhile, the high-grade coma aberration of the optical system can be balanced, and the imaging quality of the optical system is improved.

3≤|f1/(f7+f8)|≤25；

wherein f1 is an effective focal length of the first lens, f7 is an effective focal length of the seventh lens, and f8 is an effective focal length of the eighth lens. The ratio of the effective focal length of the first lens to the sum of the effective focal lengths of the seventh lens and the eighth lens can be reasonably configured when the conditional expressions are satisfied, so that the spherical aberration contributions of the first lens, the seventh lens and the eighth lens are reasonably distributed, and the on-axis area of the optical system has good imaging quality.

1≤f67/f≤1.5；

wherein f67 is a combined focal length of the sixth lens and the seventh lens, and f is an effective focal length of the optical system. The ratio of the combined focal length of the sixth lens and the seventh lens and the effective focal length of the optical system can be reasonably configured by satisfying the conditional expression, so that the combined focal length of the sixth lens and the seventh lens cannot be too strong in the optical system, thereby being beneficial to correcting the high-order spherical aberration of the optical system and further improving the imaging quality of the optical system.

0.35mm≤ET2≤0.5mm；

ET2 is the distance in the optical axis direction from the maximum effective aperture on the object side of the second lens to the maximum effective aperture on the image side of the second lens, i.e. the edge thickness of the second lens. The edge thickness of the second lens can be reasonably configured when the conditional expression is met, so that the distortion of the optical system is favorably inhibited, and the imaging quality of the optical system is improved; in addition, the surface shape of the second lens is not excessively bent or excessively gentle, and the processing and molding of the second lens are facilitated.

0.5≤|SAG61/CT6|≤1；

SAG61 is a rise of the sixth lens at the maximum effective aperture on the object-side surface, i.e. the distance from the intersection of the object-side surface of the sixth lens and the optical axis to the maximum effective aperture on the object-side surface of the sixth lens in the optical axis direction, and CT6 is the thickness of the sixth lens on the optical axis, i.e. the center thickness of the sixth lens. Satisfy above-mentioned conditional expression, can carry out rational configuration to the ratio of rise and the central thickness of sixth lens to be favorable to making the face type of sixth lens more reasonable, and then reduce the tolerance sensitivity of sixth lens, promote the machine-shaping yield of sixth lens.

5≤|V4-V5|≤10；

wherein V4 is the Abbe number of the fourth lens under d-line (587.56nm wavelength), and V5 is the Abbe number of the fifth lens under d-line. The optical system meets the conditional expression, can reasonably configure the difference between the Abbe numbers of the fourth lens and the fifth lens, is favorable for correcting the chromatic aberration of the optical system, reduces the secondary spectrum of the optical system and improves the imaging quality of the optical system.

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. Adopt above-mentioned optical system among the getting for instance the module, be favorable to realizing wide angle characteristic and big light ring characteristic, also be favorable to optical system's miniaturized design simultaneously to be favorable to reducing the size of getting for instance the 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 module of getting for instance among the electronic equipment, be favorable to realizing wide angle characteristic and big light ring characteristic, also be favorable to optical system's miniaturized design simultaneously to be favorable to reducing electronic equipment's size.

Drawings

FIG. 1 is a schematic 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 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," "transverse," "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 invention and to simplify the description, but are not intended to indicate or imply that the device or element so referred to must have a particular orientation, be constructed and operated in a particular orientation, and are not to be construed as limiting the invention.

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 explicitly stated or limited, the terms "mounted," "connected," "fixed," and the like are to be construed broadly, e.g., as being permanently connected, detachably connected, or integral; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be interconnected within two elements or in a relationship where two elements interact with each other unless otherwise specifically limited. 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 "under," "beneath," and "under" a second feature may be directly under or obliquely under the second 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, the optical system 100 includes, in order from an object side to an image side along an optical axis 110, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7, 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 with positive refractive power is helpful for shortening the total length of the optical system 100, and meets the requirement of miniaturization design of the optical system 100. The object-side surface S2 of the first lens element L1 is convex in a direction close to the optical axis 110, which is favorable for enhancing the positive refractive power of the first lens element L1, further shortening the total length of the optical system 100, and simultaneously being favorable for making the light rays in each field of view enter the optical system 100 uniformly. The image-side surface S2 of the first lens element L1 is concave at the paraxial region 110. The second lens element L2 with refractive power has a convex object-side surface S3 at a paraxial region 110 and a concave image-side surface S4 at a paraxial region 110 of the second lens element L2. The third lens element L3 has refractive power. The fourth lens element L4 with refractive power has a concave image-side surface S8 at a paraxial region 110 of the fourth lens element L4. The fifth lens element L5 with refractive power has a concave object-side surface S9 at a paraxial region 110 of the fifth lens element L5. The sixth lens element L6 has refractive power. The image-side surface S12 of the sixth lens element L6 is concave near the axis 110, which is advantageous for shortening the overall length of the optical system 100. The seventh lens element L7 with positive refractive power is favorable for improving the ability of converging light at the image side of the optical system 100. The eighth lens element L8 with negative refractive power is advantageous for correcting the aberration generated by the optical system 100 to shorten the total length of the system. The image-side surface S16 of the eighth lens element L8 is concave at the paraxial region 110, and the principal point can be located away from the image plane of the optical system 100, thereby further shortening the total length of the optical system 100. The different surface types of the lenses are matched, so that light rays entering the optical system 100 can stably pass through the surfaces of the lenses and finally irradiate on the imaging surface of the optical system 100 for imaging. Meanwhile, reasonable surface type matching is beneficial to reducing the attenuation of the optical system 100 to the shot object information and improving the lens resolving power, so that the optical system 100 has good imaging quality.

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 ir-cut filter L9 disposed on the image side of the eighth lens L8, and the ir-cut filter L9 includes an object-side surface S17 and an image-side surface S18. The infrared cut filter L9 is used to filter out interference light, and prevent the interference light from reaching the imaging surface of the optical system 100 and affecting normal imaging. 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.

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 is realized in cooperation with the miniaturization of the optical system. 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: imgH not less than 2.5mm ² V (TTL FNO) is less than or equal to 2.53 mm; where ImgH is half of the image height corresponding to the maximum field angle of the optical system 100, TTL is the 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, i.e., the total optical length of the optical system 100, and FNO is the f-number of the optical system 100. In particular ImgH ² /(TTL × FNO) may be: 2.51, 2.52 or 2.53, in units of mm. Satisfying the above conditional expressions, the half-image height, the total optical length, and the f-number of the optical system 100 can be reasonably configured, which is beneficial to expanding the maximum field angle of the optical system 100, so that the optical system 100 can acquire more scene contents, and enrich the imaging information of the optical system 100; in addition, the characteristic of large aperture of the optical system 100 is facilitated, and the light input amount of the optical system 100 is improved, so that the imaging quality of the optical system 100 in a low-light environment is improved, the optical system 100 can have a better blurring effect, and high imaging quality is metRequesting; further, it is advantageous to shorten the overall length of the optical system 100 and to realize a compact design.

In some embodiments, the optical system 100 satisfies the conditional expression: the FOV is more than or equal to 82.5 degrees and less than or equal to 84 degrees; where FOV is the maximum field angle of the optical system 100. Specifically, the FOV may be: 82.5, 82.6, 82.8, 82.9, 83, 83.1, 83.3, 83.6, 83.9 or 84, with numerical units being. When the above conditional expressions are satisfied, the optical system 100 has a wide-angle characteristic, so that the optical system 100 can acquire more scene contents and enrich imaging information of the optical system 100.

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

In some embodiments, the optical system 100 satisfies the conditional expression: f tan (HFOV) is less than or equal to 5.4mm and less than or equal to 5.5 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: 5.41, 5.42, 5.43, 5.44, 5.45, 5.46, 5.47, 5.48 or 5.49 in mm. Satisfying the above conditional expressions, the effective focal length and the maximum half field angle of the optical system 100 can be reasonably configured, which is beneficial to shortening the total length of the optical system 100 and satisfying the requirement of miniaturization design; meanwhile, the deflection angle of the light in the optical system 100 can be reduced, so that the surface shape of each lens in the optical system 100 can not be excessively bent or excessively gentle, and the yield of injection molding of each lens can be improved; moreover, the optical system 100 has a large image plane characteristic, so that the optical system 100 can be matched with a photosensitive element with a larger size, and the imaging quality of the optical system 100 can be improved.

In some embodiments, the optical system 100 satisfies the conditional expression: TTL/ImgH is more than or equal to 1.35 and less than or equal to 1.4. Specifically, TTL/ImgH may be: 1.37 or 1.38. Satisfying the above conditional expressions is advantageous for shortening the total system length of the optical system 100 and satisfying the requirement of the miniaturized design. Below the lower limit of the above conditional expression, the total system length of the optical system 100 is too short and/or the half-image height is too large, which results in poor edge imaging, and is not beneficial to improving the imaging quality of the optical system 100 while realizing the miniaturization design requirement; exceeding the upper limit of the above conditional expression is disadvantageous in the miniaturization of the optical system 100 because the total length of the optical system 100 is too long.

In some embodiments, the optical system 100 satisfies the conditional expression: the absolute value of R13+ R14/| R13-R14| is more than or equal to 1.2; wherein R13 is a radius of curvature of the object-side surface S13 of the seventh lens element L7 along the optical axis 110, and R14 is a radius of curvature of the image-side surface S14 of the seventh lens element L7 along the optical axis 110. Specifically, | R13+ R14|/| R13-R14| may be: 1.015, 1.033, 1.043, 1.067, 1.099, 1.122, 1.130, 1.139, 1.140, or 1.142. The surface shape of the seventh lens L7 can be reasonably configured to ensure that the surface shape of the seventh lens L7 is not excessively curved or excessively gentle when the conditional expressions are satisfied, so that the tolerance sensitivity of the seventh lens L7 is favorably reduced, and the injection molding yield of the seventh lens L7 is improved; meanwhile, the high-level coma aberration of the optical system 100 is balanced, and the imaging quality of the optical system 100 is improved.

In some embodiments, the optical system 100 satisfies the conditional expression: | f1/(f7+ f8) | is not less than 3 and not more than 25; where f1 is the effective focal length of the first lens L1, f7 is the effective focal length of the seventh lens L7, and f8 is the effective focal length of the eighth lens L8. Specifically, | f1/(f7+ f8) | may be: 3.43, 5.36, 7.31, 8.39, 11.25, 13.15, 16.58, 19.33, 20.02 or 24.44. Satisfying the above conditional expressions, the ratio of the effective focal length of the first lens L1 to the sum of the effective focal lengths of the seventh lens L7 and the eighth lens L8 can be configured reasonably, so as to distribute the spherical aberration contributions of the first lens L1, the seventh lens L7 and the eighth lens L8 reasonably, and further enable the on-axis area of the optical system 100 to have good imaging quality.

In some embodiments, the optical system 100 satisfies the conditional expression: f67/f is more than or equal to 1 and less than or equal to 1.5; where f67 is the combined focal length of the sixth lens L6 and the seventh lens L7, and f is the effective focal length of the optical system 100. Specifically, f67/f may be: 1.00, 1.05, 1.09, 1.11, 1.15, 1.18, 1.20, 1.25, 1.27, or 1.31. Satisfying the above conditional expressions, the ratio of the combined focal length of the sixth lens L6 and the seventh lens L7 to the effective focal length of the optical system 100 can be configured reasonably, so that the combined focal length of the sixth lens L6 and the seventh lens L7 is not too strong in the optical system 100, which is favorable for correcting the high-order spherical aberration of the optical system 100, and further improves the imaging quality of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: ET2 is more than or equal to 0.35mm and less than or equal to 0.5 mm; ET2 is the distance from the maximum effective aperture of the object-side surface S3 of the second lens L2 to the maximum effective aperture of the image-side surface S4 of the second lens L2 in the direction of the optical axis 110, i.e., the edge thickness of the second lens L2. Specifically, ET2 may be: 0.36, 0.37, 0.38, 0.39, 0.40, 0.41, 0.42 or 0.43, in units of mm. Satisfying the above conditional expression, the edge thickness of the second lens L2 can be reasonably configured, thereby being beneficial to suppressing the distortion of the optical system 100 and further improving the imaging quality of the optical system 100; in addition, the surface shape of the second lens L2 is not excessively curved or excessively gentle, which is beneficial to the processing and molding of the second lens L2.

In some embodiments, the optical system 100 satisfies the conditional expression: the absolute value of SAG61/CT6 is more than or equal to 0.5 and less than or equal to 1; SAG61 is the rise of the sagittal height of the sixth lens L6 at the maximum effective aperture of the object-side surface S1, that is, the distance from the intersection point of the object-side surface S1 of the sixth lens L6 and the optical axis 110 to the maximum effective aperture of the object-side surface S11 of the sixth lens L6 in the direction of the optical axis 110, and CT6 is the thickness of the sixth lens L6 on the optical axis 110, that is, the center thickness of the sixth lens L6. Specifically, | SAG61/CT6| can be: 0.60, 0.62, 0.63, 0.65, 0.68, 0.70, 0.74, 0.75, 0.76 or 0.77. Satisfying above-mentioned conditional expression, can rationally disposing the ratio of rise and the central thickness of sixth lens L6 to be favorable to making the face type of sixth lens L6 more reasonable, and then reduce sixth lens L6's tolerance sensitivity, promote the machine-shaping yield of sixth lens L6.

In some embodiments, the optical system 100 satisfies the conditional expression: V4-V5 is more than or equal to 5 and less than or equal to 10; wherein V4 is the abbe number of the fourth lens L4 under d-line (587.56nm wavelength), and V5 is the abbe number of the fifth lens L5 under d-line. Specifically, | V4-V5| may be 7.95. Satisfying the above conditional expressions, the difference between abbe numbers of the fourth lens L4 and the fifth lens L5 can be configured reasonably, which is beneficial to correcting chromatic aberration of the optical system 100, and reducing the secondary spectrum of the optical system 100, thereby improving the imaging quality of the optical system 100.

The reference wavelengths of the effective focal lengths are 555nm, and the reference wavelengths of the Abbe numbers are 587.56 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 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. 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 convex at the periphery;

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

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

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

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 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 concave 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 the paraxial region 110 and convex at the periphery.

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: ImgH ² V (TTL × FNO) ═ 2.51 mm; where ImgH is half of the image height corresponding to the maximum field angle of the optical system 100, TTL is the 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, i.e., the total optical length of the optical system 100, and FNO is the f-number of the optical system 100. Satisfying the above conditional expressions, the half-image height, the total optical length, and the f-number of the optical system 100 can be reasonably configured, which is beneficial to expanding the maximum field angle of the optical system 100, so that the optical system 100 can acquire more scene contents, and enrich the imaging information of the optical system 100; in addition, the optical system 100 is also favorable for realizing the characteristic of a large aperture, and the light input quantity of the optical system 100 is improved, so that the imaging quality of the optical system 100 in a low-light environment is improved, the optical system 100 can have a better blurring effect, and the requirement of high imaging quality is further met; further, it is advantageous to shorten the total length of the optical system 100 and to realize a compact design.

The optical system 100 satisfies the conditional expression: f tan (hfov) ═ 5.41 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. Satisfying the above conditional expressions, the effective focal length and the maximum half field angle of the optical system 100 can be reasonably configured, which is beneficial to shortening the total length of the optical system 100 and satisfying the requirement of miniaturization design; meanwhile, the deflection angle of the light in the optical system 100 can be reduced, so that the surface shape of each lens in the optical system 100 can not be excessively bent or excessively gentle, and the yield of injection molding of each lens can be improved; moreover, the optical system 100 has a large image plane characteristic, so that the optical system 100 can be matched with a photosensitive element with a larger size, and the imaging quality of the optical system 100 can be improved.

The optical system 100 satisfies the conditional expression: TTL/ImgH is 1.38. Satisfying the above conditional expressions is advantageous for shortening the total system length of the optical system 100 and satisfying the requirement of miniaturization design; .

The optical system 100 satisfies the conditional expression: r13+ R14/| R13-R14| ═ 1.121; wherein R13 is a radius of curvature of the object-side surface S13 of the seventh lens element L7 along the optical axis 110, and R14 is a radius of curvature of the image-side surface S14 of the seventh lens element L7 along the optical axis 110. The surface shape of the seventh lens L7 can be reasonably configured to ensure that the surface shape of the seventh lens L7 is not excessively bent or excessively gentle when the conditional expressions are met, so that the tolerance sensitivity of the seventh lens L7 is reduced, and the injection molding yield of the seventh lens L7 is improved; meanwhile, the high-level coma aberration of the optical system 100 can be balanced, and the imaging quality of the optical system 100 can be improved.

The optical system 100 satisfies the conditional expression: i f1/(f7+ f8) | 12.14; where f1 is the effective focal length of the first lens L1, f7 is the effective focal length of the seventh lens L7, and f8 is the effective focal length of the eighth lens L8. Satisfying the above conditional expressions, the ratio of the effective focal length of the first lens L1 to the sum of the effective focal lengths of the seventh lens L7 and the eighth lens L8 can be configured reasonably, so as to distribute the spherical aberration contributions of the first lens L1, the seventh lens L7 and the eighth lens L8 reasonably, and further enable the on-axis area of the optical system 100 to have good imaging quality.

The optical system 100 satisfies the conditional expression: f67/f is 1.24; where f67 is the combined focal length of the sixth lens L6 and the seventh lens L7, and f is the effective focal length of the optical system 100. Satisfying the above conditional expressions, the ratio of the combined focal length of the sixth lens L6 and the seventh lens L7 to the effective focal length of the optical system 100 can be configured reasonably, so that the combined focal length of the sixth lens L6 and the seventh lens L7 is not too strong in the optical system 100, which is beneficial to correcting the high-order spherical aberration of the optical system 100, and further improves the imaging quality of the optical system 100.

The optical system 100 satisfies the conditional expression: ET2 ═ 0.40 mm; ET2 is the distance from the maximum effective aperture of the object-side surface S3 of the second lens L2 to the maximum effective aperture of the image-side surface S4 of the second lens L2 in the direction of the optical axis 110, i.e., the edge thickness of the second lens L2. Satisfying the above conditional expression, the edge thickness of the second lens L2 can be reasonably configured, which is beneficial to suppressing the distortion of the optical system 100, and further improves the imaging quality of the optical system 100; in addition, the second lens L2 is not excessively curved or flat in surface shape, which is beneficial to the processing and molding of the second lens L2.

The optical system 100 satisfies the conditional expression: 0.75 | SAG61/CT6 |; here, SAG61 is the saggital height at the maximum effective aperture of the object-side surface S1 of the sixth lens L6, and CT6 is the thickness of the sixth lens L6 on the optical axis 110, that is, the center thickness of the sixth lens L6. Satisfying above-mentioned conditional expression, can rationally configuring the ratio of rise and the central thickness of sixth lens L6 to be favorable to making the face type of sixth lens L6 more reasonable, and then reduce sixth lens L6's tolerance sensitivity, promote sixth lens L6's machine-shaping yield.

The optical system 100 satisfies the conditional expression: V4-V5| ═ 7.95; wherein V4 is the abbe number of the fourth lens L4 under d-line (587.56nm wavelength), and V5 is the abbe number of the fifth lens L5 under d-line. Satisfying the above conditional expression, the difference between the abbe numbers of the fourth lens L4 and the fifth lens L5 can be configured reasonably, which is beneficial to correcting chromatic aberration of the optical system 100, and reducing the secondary spectrum of the optical system 100, thereby improving the imaging quality of the optical system 100.

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 cut filter L9, but the distance from the image side surface S16 to the image surface S19 of the eighth lens L8 is kept constant at this time.

In the first embodiment, the effective focal length f of the optical system 100 is 6.14mm, the f-number FNO is 1.59, the maximum field angle FOV is 82.8 °, and the total optical length TTL is 7.6 mm. In the first embodiment and the subsequent embodiments, the relation is satisfied: TTL is not less than 7.55mm and not more than 7.6 mm; FNO 1.59; the optical system can be designed to be compact and to have a large aperture.

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

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 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. 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 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 the paraxial region 110 and is convex at the peripheral region;

the object-side surface S7 of the fourth lens element L4 is convex at a position near the optical axis 110 and is concave at the circumference;

the object-side surface S9 of the fifth lens element L5 is concave at the paraxial region 110 and is concave at the 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 S13 of the seventh lens element L7 is convex at the paraxial region 110 and concave at the peripheral region;

the object-side surface S15 of the eighth lens element L8 is convex at 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.

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

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

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 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. 6 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the third embodiment, from left to right.

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

In addition, the parameters of the optical system 100 are given in table 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

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 negative 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.

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

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

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

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

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 positive 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 negative 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.

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 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 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.

TABLE 10

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 negative refractive power, a seventh lens element L7 with positive 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.

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

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 derived from the first embodiment, which is not repeated herein.

TABLE 12

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

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 ir-cut filter L9, wherein the ir-cut filter L9 is disposed between the image side S16 and the image plane 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. The optical system 100 is adopted in the image capturing module 200, which is beneficial to realizing the wide-angle characteristic and the large aperture characteristic, and is also beneficial to the miniaturization design of the optical system 100, thereby being beneficial to reducing the size 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 smart watch or an onboard image capturing apparatus such as a cellular phone, a video phone, a smart phone, an electronic book reader, and a vehicle data recorder. 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 realizing the wide-angle characteristic and the large aperture characteristic, and is also beneficial to the miniaturization design of the optical system 100, thereby being beneficial to reducing the size 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 invention. 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 eight lens elements with refractive power, 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 third lens element with refractive power;

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

a seventh 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; and

and the optical system satisfies the following conditional expression:

2.5mm≤ImgH ² /（TTL*FNO）≤2.53mm；

0.5≤|SAG61/CT6|≤1；

wherein ImgH is a half of an image height corresponding to a maximum field angle of the optical system, TTL is a distance on an optical axis from an object-side surface of the first lens to an image plane of the optical system, FNO is an f-number of the optical system, SAG61 is a rise at a maximum effective aperture of an object-side surface of the sixth lens, and CT6 is a thickness of the sixth lens on the optical axis.

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

5.4mm≤f*tan(HFOV) ≤5.5mm；

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

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

1.35≤TTL/ImgH≤1.4。

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

1≤|R13+R14|/|R13-R14|≤1.2；

wherein R13 is a radius of curvature of an object-side surface of the seventh lens element at an optical axis, and R14 is a radius of curvature of an image-side surface of the seventh lens element at the optical axis.

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

3≤|f1/(f7+f8)|≤25；

wherein f1 is an effective focal length of the first lens, f7 is an effective focal length of the seventh lens, and f8 is an effective focal length of the eighth lens.

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

1≤f67/f≤1.5；

wherein f67 is a combined focal length of the sixth lens and the seventh lens, and f is an effective focal length of the optical system.

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

0.35mm≤ET2≤0.5mm；

ET2 is a distance in the optical axis direction from the maximum effective aperture on the object side of the second lens to the maximum effective aperture on the image side of the second lens.

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

82.5°≤FOV≤84°；

7.55mm≤TTL≤7.6mm；

wherein the FOV is a maximum field angle of the optical system.

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

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