CN114740594A

CN114740594A - Optical system, camera module and electronic equipment

Info

Publication number: CN114740594A
Application number: CN202210220532.0A
Authority: CN
Inventors: 龙鑫灿; 李明
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2022-03-08
Filing date: 2022-03-08
Publication date: 2022-07-12
Anticipated expiration: 2042-03-08
Also published as: CN114740594B

Abstract

The invention discloses an optical system, a camera module and electronic equipment. The optical system sequentially comprises a first lens with positive refractive power, a second lens with negative refractive power, a third lens with positive refractive power and a fourth lens with refractive power from an object side to an image side along an optical axis; the optical system comprises a fifth lens element with positive refractive power, a sixth lens element with negative refractive power, a seventh lens element with positive refractive power, and an eighth lens element with negative refractive power, wherein the optical system satisfies the following relations: 1.6< ∑ CT/Σ AT < 2.4; the optical system of the embodiment of the application has large image plane characteristics and a miniaturized design, and can meet the requirements of large-range shooting and high imaging quality.

Description

Optical system, camera module and electronic equipment

Technical Field

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

Background

Along with the development of the camera technology, the market demand of portable electronic equipment such as smart phones, smart watches and smart glasses is greatly increased, and the lens can acquire image information and is a main module for realizing image shooting of the electronic equipment. An image sensor of a general lens may be a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor, and with the refinement of Semiconductor process technology, the pixel size of the image sensor is reduced, and the lens is gradually developed in the high pixel field, so that the requirements of consumers for the imaging quality, functions and the like of the lens are higher and higher, and the lens is required to be thinner and smaller, and at the same time, higher imaging quality is also achieved.

Disclosure of Invention

The present invention is directed to solving at least one of the problems of the prior art. Therefore, the present application provides an optical system that can achieve both a large image plane design and a small design, so as to effectively solve the problem of good imaging quality.

The invention also provides a camera module in a second aspect.

The third aspect of the present invention further provides an electronic device.

The optical system according to the first aspect of the present application, in order from an object side to an image side along an optical axis, comprises: 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 positive refractive power having a convex object-side surface at paraxial region; a fourth lens element with refractive power; a fifth lens element with positive refractive power having a convex image-side surface at paraxial region; a sixth lens element with negative refractive power having a concave image-side surface at paraxial region; a seventh lens element with positive refractive power having a convex object-side surface at paraxial region; the eighth lens element with negative refractive power has a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region.

In the optical system, the positive refractive power of the first lens element is matched with the convex-concave design of the object-side surface and the image-side surface at the paraxial region, so that the incident light with large angle can enter the optical system and can be effectively converged. The first lens element can smoothly transmit incident light rays converged by the second lens element and correct primary aberration caused by converging incident light rays by matching with negative refractive power of the second lens element and convex-concave design at a paraxial region. Meanwhile, by matching with the positive refractive power of the third lens element and the convex design of the object-side surface at the paraxial region, the light rays in the central and peripheral fields can be further converged, so that the total length of the optical system is reduced, and the aberration caused by the first lens element and the second lens element and difficult to correct is eliminated. The fourth lens element with refractive power can effectively correct aberration generated when light passes through the object lens elements (i.e., the first lens element to the third lens element), and reduce the correction pressure of the rear lens elements (i.e., the fifth lens element to the eighth lens element). The positive refractive power of the fifth lens element can correct aberration generated when light passes through the fourth lens element, and the positive and negative lens elements can cancel out aberration generated when light passes through the fourth lens element, so that the negative refractive power of the sixth lens element can cancel out aberration generated when light passes through the sixth lens element, and the image-side surface of the fifth lens element is designed to have a convex surface shape at the paraxial region, and the light of the central field of view can be further converged by matching with the concave surface shape of the image-side surface of the sixth lens element at the paraxial region, thereby compressing the total length of the optical system. The object side surface of the seventh lens element is convex at the paraxial region, so that the positive refractive power of the seventh lens element can be enhanced, the astigmatism of the optical system can be balanced, the eighth lens element with negative refractive power can be used for correcting the distortion of the optical system, meanwhile, the object side surface of the eighth lens element is convex at the paraxial region, and the image side surface of the eighth lens element is concave at the paraxial region, so that light can be incident on the imaging surface more smoothly, and the main light incident angle of each visual field on the imaging surface can be reduced, thereby improving the photosensitive efficiency and enhancing the imaging quality.

In one embodiment, the optical system satisfies the relationship: 1.6< ∑ CT/Σ AT < 2.4; Σ CT is the sum of the lens thicknesses of the first lens to the eighth lens on the optical axis, and Σ AT is the sum of the intervals between two adjacent lenses of the first lens to the eighth lens on the optical axis. Through satisfying the conditional expression, the central thickness of all lenses on the optical axis, the air space on the optical axis between any two adjacent lenses in the first lens to the eighth lens can be controlled, and each lens has enough design and arrangement space, thereby not only being beneficial to processing and assembling each lens in the optical system, but also ensuring that the optical system has smaller optical total length, and being beneficial to realizing the miniaturization design of the optical system.

In one embodiment, the optical system satisfies the relationship: 9.5< f FNO/T45< 13; and/or, 2.8mm < f/FNO <3 mm; f is an effective focal length of the optical system, FNO is an f-number of the optical system, and T45 is a distance on an optical axis from an object side surface of the fourth lens to an image side surface of the fifth lens. By satisfying the conditional expression: 9.5< f FNO/T45<13, the optical system not only can realize the miniaturized design, but also can ensure enough light flux to meet the imaging requirements of the optical system on high image quality and high definition. When f × FNO/T45 is not greater than 9.5, on the premise that the optical system satisfies sufficient light flux, the distance between the object side surface of the fourth lens element and the image side surface of the fifth lens element on the optical axis is increased, so that the total length of the optical system is increased, which is not favorable for miniaturization design, and when f × FNO/T45 is not less than 13, the effective light flux of the optical system is easily affected, which results in low accuracy of capturing images by the optical system and is not favorable for the design requirement of high resolution imaging quality of the optical system.

The conditional expression is satisfied: 2.8mm < f/FNO <3mm, can control the ratio of effective focal length of optical system and optical system's f-number in reasonable scope for optical system obtains longer focal length when satisfying the miniaturization, in addition, can make optical system obtain sufficient light flux when shooing, in order to realize that optical system obtains high picture quality, high definition's imaging effect. When f/FNO is less than or equal to 2.8mm, the diaphragm number of the optical system is too large, so that the diaphragm is too small, the light incoming amount is insufficient, the shooting effect of the optical system in a dark environment is reduced, and the effective focal length of the optical system is small at the moment, so that the optical system cannot shoot a distant scene; when f/FNO is larger than or equal to 3mm, the diaphragm number of the optical system is too small, so that the diaphragm is too large, the design and manufacturing difficulty of the optical system is increased, and the effective focal length of the optical system is too long, so that the shooting field of view is difficult to expand.

In one embodiment, the optical system satisfies the relationship: 5.5< ∑ CT/CT1< 11; Σ CT is the sum of the lens thicknesses of the first lens to the eighth lens on the optical axis, and CT1 is the thickness of the first lens on the optical axis. The optical system meets the conditional expression, and the total length of the optical system can be effectively shortened and the imaging quality of the optical system can be ensured by adjusting the proportional relation between the total thickness of the first lens to the eighth lens on the optical axis and the thickness of the first lens on the optical axis, so that the miniaturization design requirement of the optical system can be realized while the imaging quality of the optical system is ensured.

In one embodiment, the optical system satisfies the relationship: 1< f1/f < 1.5; f1 is the effective focal length of the first lens. The optical system meets the conditional expression, the contribution of the first lens to the total focal power of the optical system is proper by reasonably configuring the relationship between the effective focal length of the first lens and the effective focal length of the optical system, the aberration correction capability of the optical system is favorably improved, and in addition, the first lens can be matched with other lenses (the second lens to the eighth lens) to ensure that the optical system has a better aberration correction effect, so that the optical system is ensured to have good imaging quality. When f1/f is less than or equal to 1, the effective focal length of the optical system is too large, a large field angle cannot be obtained, and high-resolution imaging of the optical system is not facilitated; when f1/f is greater than or equal to 1.5, the effective focal length of the first lens element is too large, and the contribution to the total focal power of the optical system is insufficient, so that the refractive power burden from the second lens element to the eighth lens element is increased, and the improvement of the aberration correction capability of the optical system is not facilitated.

In one embodiment, the optical system satisfies the relationship: 1< | R2+ R3|/| R2-R3| < 2.5; r2 is a radius of curvature of an object-side surface of the first lens at an optical axis, and R3 is a radius of curvature of an image-side surface of the first lens at the optical axis. Satisfy above-mentioned conditional expression, the camber change trend of the object side face and the image side face of first lens can be controlled well, thereby make first lens thickness ratio trend mild, and then restrict the shape of first lens, be favorable to controlling the spherical aberration of first lens, make the imaging quality of the visual field of on-axis and the visual field outside the optical axis can not produce obvious degradation because of the contribution change of spherical aberration, still be favorable to improving optical system's optical performance, simultaneously, first lens face type changes gently, can reduce the manufacturing degree of difficulty of first lens, thereby improve the processing yield.

In one embodiment, the optical system satisfies the relationship: 1< SD42/SD41< 1.2; SD41 is half the maximum effective aperture of the object-side surface of the fourth lens, and SD42 is half the maximum effective aperture of the image-side surface of the fourth lens. By satisfying the conditional expressions, the aperture of the object side surface of the fourth lens and the aperture of the image side surface of the fourth lens can be reasonably configured, and the radial size of the fourth lens is further reduced, so that the small head design of the optical system is facilitated. When the optical system is applied to the electronic equipment, the opening size of the optical system on the screen of the electronic equipment can be reduced, and the screen occupation ratio of the electronic equipment is further improved. In addition, when the above relation is satisfied, the edge size of the fourth lens does not change too drastically, so that the workability of the lens is improved, and the fourth lens having a larger aperture is also advantageous in enlarging the aperture, maintaining the optical system to have a good light transmission amount, and thus enabling the optical system to have a high image quality. When SD41/SD42 is less than or equal to 1, the deflection degree of incident light in the fourth lens is too large, off-axis aberration is easy to increase, and the imaging quality of the optical system is reduced; when SD41/SD42 is 1.5 or more, the radial dimension of the fourth lens is too large, and it is difficult to design a small head of the optical system.

In one embodiment, the optical system satisfies the relationship: 5< f7/CT7< 10.5; f7 is an effective focal length of the seventh lens, and CT7 is a thickness of the seventh lens on an optical axis. Through satisfying the conditional expression, can reduce the tolerance sensitivity of seventh lens center thickness, reduce the processing degree of difficulty of seventh lens, be favorable to promoting optical system's equipment yield, further reduction in production cost to through satisfying the relational expression, can avoid seventh lens effective focal length too big, optical system to produce difficult astigmation of rectifying, thereby improve optical system's imaging quality, can avoid the center thickness of seventh lens too big simultaneously, do benefit to optical system's miniaturized design. When f7/CT7 is not more than 5, or f7/CT7 is not less than 10.5, tolerance sensitivity of the center thickness of the seventh lens is high, processing difficulty of the seventh lens is increased, improvement of assembly yield of the optical system is not facilitated, and production cost is further increased.

In one embodiment, the optical system satisfies the relationship: 6.2mm < f tan (hfov) <6.7 mm; f is the effective focal length of the optical system, and the HFOV is half of the maximum field angle of the optical system. The conditional expression is satisfied, through the interrelation of the maximum field angle of the total effective focal length of reasonable setting optical system and optical system, be favorable to enlarging optical system's field angle in order to realize wide angle characteristic, make optical system can acquire more scene contents, suitable effective focal length still can restrain optical system's distortion, thereby promote optical system's imaging quality, and simultaneously, satisfy the relational expression, also be favorable to enlarging the formation of image circle in order to realize big image plane characteristic, thereby richen optical system's imaging information, in addition, still be favorable to shortening optical system's overall length, realize miniaturized design. Therefore, the optical system can be designed in a miniaturized manner, and is favorable for realizing high-pixel and large-image-plane characteristics of the optical system, so that the shooting effect is improved, and the imaging quality is improved.

The camera module according to the second aspect of the present application includes a photosensitive chip and the optical system described above, where the photosensitive chip is disposed on the image side of the optical system. Through adopting above-mentioned optical system, the module of making a video recording has big image plane characteristic and miniaturized design, can satisfy shoot on a large scale and high imaging quality's demand.

According to the third aspect of the present application, the electronic device includes a fixing member and the camera module set, and the camera module set is disposed on the fixing member. The camera module can realize large image surface characteristics and miniaturization design, and can meet the requirements of large-range shooting and high imaging quality.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

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

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

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

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

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

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

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

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

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

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

fig. 11 is a schematic view of a camera module according to an embodiment of the second aspect of the present application;

fig. 12 is a schematic structural diagram of an electronic device according to an embodiment of the third aspect of the present application.

Reference numerals:

an optical system 10, a camera module 20, an electronic device 30,

the optical axis 101, the optical filter 110, the photosensitive chip 210, the fixing member 310,

stop STO, first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, seventh lens L7, eighth lens L8,

a first lens object-side surface S1, a first lens image-side surface S2, a second lens object-side surface S3, a second lens image-side surface S4, a third lens object-side surface S5, a third lens image-side surface S6, a fourth lens object-side surface S7, a fourth lens image-side surface S8, a fifth lens object-side surface S9, a fifth lens image-side surface S10, a sixth lens object-side surface S11, a sixth lens image-side surface S12, a seventh lens object-side surface S13, a seventh lens image-side surface S14, an eighth lens object-side surface S15, an eighth lens image-side surface S16, a filter object-side surface S17, a filter image-side surface S18, and an image-forming surface S19.

Detailed Description

Reference will now be made in detail to embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like or similar reference numerals refer to the same or similar elements or elements having the same or similar function throughout. The embodiments described below with reference to the drawings are illustrative and intended to be illustrative of the invention and are not to be construed as limiting the invention.

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

Referring to fig. 1, the present application provides an optical system 10 with an eight-lens design, and the optical system 10 includes, in order from an object side to an image side along an optical axis 101, 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 or 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. The lenses in the optical system 10 should be coaxially arranged, the common axis of the lenses is the optical axis 101 of the optical system 10, and the lenses can be installed in a lens barrel to form an image pickup lens.

The first lens L1 has an object side surface S1 and an image side surface S2, the second lens L2 has an object side surface S3 and an image side surface S4, the third lens L3 has an object side surface S5 and an image side surface S6, the fourth lens L4 has an object side surface S7 and an image side surface S8, the fifth lens L5 has an object side surface S9 and an image side surface S10, the sixth lens L6 has an object side surface S11 and an image side surface S12, the seventh lens L7 has an object side surface S13 and an image side surface S14, and the eighth lens L8 has an object side surface S15 and an image side surface S16. Meanwhile, the optical system 10 further has an image plane S19, the image plane S19 is located on the image side of the eighth lens element L8, and light rays emitted from an on-axis object point at a corresponding object distance can be converged on the image plane S19 after being adjusted by each lens element of the optical system 10.

Generally, the image forming surface S19 of the optical system 10 coincides with the light sensing surface of the light sensing chip. It should be noted that in some embodiments, the optical system 10 may be matched with an image sensor having a rectangular photosensitive surface, and the imaging surface S19 of the optical system 10 coincides with the rectangular photosensitive surface of the image sensor. At this time, the effective pixel area on the imaging surface S19 of the optical system 10 has a horizontal direction, a vertical direction, and a diagonal direction, and in this application, the maximum angle of view of the optical system 10 is understood to be the maximum angle of view of the optical system 10 in the diagonal direction, and the image height corresponding to the maximum angle of view is understood to be half the length of the effective pixel area on the imaging surface S19 of the optical system 10 in the diagonal direction.

In the embodiment of the present application, the object-side surface S1 of the first lens element L1 is convex at the paraxial region 101, and the image-side surface S2 is concave at the paraxial region 101; the object-side surface S3 of the second lens element L2 is convex at the paraxial region 101, and the image-side surface S4 is concave at the paraxial region 101; the object-side surface S5 of the third lens element L3 is convex at the paraxial region 101; the image-side surface S10 of the fifth lens element L5 is convex at the paraxial region 101; the image-side surface S12 of the sixth lens element L6 is concave at the paraxial region 101, and the object-side surface S13 of the seventh lens element L7 is convex at the paraxial region 101; the object-side surface S15 of the eighth lens element L8 is convex at the paraxial region 101, and the image-side surface S16 is concave at the paraxial region 101. When it is described that a lens surface has a certain profile at a paraxial region 101, that is, the lens surface has the certain profile in the vicinity of the optical axis 101; when describing a lens surface as having a profile near the maximum effective aperture, the lens surface has the profile radially and near the maximum effective clear aperture.

In the optical system 10, the positive refractive power of the first lens element L1, combined with the convex-concave design of the object-side surface S1 and the image-side surface S2 at the position near the optical axis 101, is favorable for the incident light with large angle to enter the optical system 10 and to be effectively converged. In combination with the negative refractive power of the second lens element L2 and the convex-concave design at the paraxial region 101, the incident light converged by the first lens element L1 can be smoothly transmitted, and the primary aberration caused by the converging incident light of the first lens element L1 can be corrected. By combining the positive refractive power of the third lens element L3 and the convex design of the object-side surface S5 at the paraxial region 101, the central and peripheral field rays can be further converged, thereby reducing the total length of the optical system 10 and eliminating the uncorrectable aberrations caused by the first lens element L1 and the second lens element L2. The fourth lens element L4 with refractive power can effectively correct the aberration generated by the light passing through the object lens element (i.e., the first lens element L1 to the third lens element L3), and reduce the correction pressure of the rear lens element (i.e., the fifth lens element L5 to the eighth lens element L8). The positive refractive power of the fifth lens element L5 can correct the aberration generated when light passes through the fourth lens element L4, and the positive and negative refractive powers can cancel each other out the aberration generated when light passes through the sixth lens element L5, so that the negative refractive power of the sixth lens element L6 can cancel the aberration generated when light passes through the sixth lens element L5, and the convex design of the image-side surface S10 of the fifth lens element L5 at the paraxial region 101 can further converge the light of the central field of view by matching with the concave design of the image-side surface S12 of the sixth lens element L6 at the paraxial region 101, thereby reducing the total length of the optical system 10. The object-side surface S13 of the seventh lens element L7 is convex at the paraxial region 101, which can enhance the positive refractive power of the seventh lens element L7, and is favorable for balancing the astigmatism of the optical system, and the object-side surface S15 of the eighth lens element L8 is convex at the paraxial region 101 and the image-side surface S16 is concave at the paraxial region 101, which is favorable for making the light beam more smoothly incident on the image plane S19, which is favorable for reducing the chief ray incident angle of each field on the image plane S19, thereby improving the light sensing efficiency and enhancing the image quality.

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

1.6<∑CT/ΣAT<2.4；

Σ CT is the sum of the lens thicknesses of the first lens L1 to the eighth lens L8 on the optical axis 101, that is, on the optical axis 101, the lens thickness of the first lens L1, the lens thickness of the second lens L2, the lens thickness of the third lens L3, the lens thickness of the fourth lens L4, the lens thickness of the fifth lens L5, the lens thickness of the sixth lens L6, the lens thickness of the seventh lens L7, the lens thickness of the eighth lens L8, and Σ AT is the sum of the spacings of adjacent two lenses in the first lens L1 to the eighth lens L8 on the optical axis 101, that is, on the optical axis 101, the distance between the image-side surface S2 of the first lens L1 and the object-side surface S3 of the second lens L2, the distance between the image-side surface S3 of the first lens L3 to the object-side surface S3 of the second lens L3, the distance between the image-side surface S3 of the second lens L3 to the image-side surface S3 of the second lens L3, the distance between the image-side surface S3 of the second lens L3 and the third lens L3, and the distance between the object-side surface S3 of the third lens L3, and the object-side surface S3 of the fourth lens L3, A distance between the image-side surface S8 of the fourth lens L4 and the object-side surface S9 of the fifth lens L5, a distance between the image-side surface S10 of the fifth lens L5 and the object-side surface S11 of the sixth lens L6, a distance between the image-side surface S12 of the sixth lens L1 and the object-side surface S13 of the seventh lens L7, and a distance between the image-side surface S14 of the seventh lens L7 and the object-side surface S15 of the eighth lens L8.

By satisfying the conditional expressions, the central thicknesses of all the lenses on the optical axis 101 and the air intervals between any two adjacent lenses of the first lens L1 to the eighth lens L8 on the optical axis 101 can be controlled, and each lens has sufficient design and arrangement space, which is not only beneficial to the processing and assembly of each lens in the optical system 10, but also can ensure that the optical system 10 has a small optical total length, thereby being beneficial to the miniaturization design of the optical system 10.

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

9.5<f*FNO/T45<13；

f is the effective focal length of the optical system 10, FNO is the f-number of the optical system 10, and T45 is the distance from the object-side surface S7 of the fourth lens L4 to the image-side surface S10 of the fifth lens L5 on the optical axis 101.

By satisfying the conditional expressions, the optical system 10 can not only realize a miniaturized design, but also ensure a sufficient amount of light to satisfy the imaging requirements of the optical system 10 for high image quality and high definition. When f × FNO/T45 is not greater than 9.5, the distance from the object-side surface S7 of the fourth lens L4 to the image-side surface S10 of the fifth lens L5 on the optical axis 101 is increased on the premise that the optical system 10 satisfies the sufficient light flux amount, and the total length of the optical system 10 is further increased, which is not favorable for the miniaturization design, and when f × FNO/T45 is not less than 13, the effective light flux amount of the optical system 10 is easily affected, which results in low accuracy of capturing images by the optical system 10 and is not favorable for the design requirement of high resolution imaging quality of the optical system 10.

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

2.8mm<f/FNO<3mm；

f is the effective focal length of the optical system 10, and FNO is the f-number of the optical system 10.

By satisfying the conditional expressions, the ratio of the effective focal length of the optical system 10 to the f-number of the optical system 10 can be controlled within the above range, so that the optical system 10 can obtain a longer focal length while satisfying miniaturization, and in addition, the optical system 10 can obtain a sufficient amount of light flux at the time of shooting, so that the optical system 10 can obtain an imaging effect of high image quality and high definition. When f/FNO is less than or equal to 2.8mm, the f-number of the optical system 10 is too large, so that the aperture is too small, the light incoming amount is insufficient, the shooting effect of the optical system 10 in a dark environment is reduced, and the effective focal length of the optical system 10 is also small, so that the optical system 10 cannot shoot a distant scene; when f/FNO is larger than or equal to 3mm, the diaphragm number of the optical system 10 is too small, which results in too large diaphragm, so that the design and manufacture difficulty of the optical system 10 is increased, and the effective focal length of the optical system 10 is too long, which is difficult to enlarge the shooting field of view.

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

5.5<∑CT/CT1<11；

Σ CT is the sum of the lens thicknesses of the first lens L1 to the eighth lens L8 on the optical axis 101, that is, on the optical axis 101, the thickness of the first lens L1, the thickness of the second lens L2, the thickness of the third lens L3, the thickness of the fourth lens L4, the thickness of the fifth lens L5, the thickness of the sixth lens L6, the thickness of the seventh lens L7, and the thickness of the eighth lens L8, and CT1 is the thickness of the first lens L1 on the optical axis 101.

By adjusting the proportional relationship between the total lens thickness of the first lens L1 through the eighth lens L8 on the optical axis 101 and the thickness of the first lens L1 on the optical axis 101, the total length of the optical system 10 can be effectively shortened, the imaging quality of the optical system 10 can be ensured, and the design requirement of miniaturization of the optical system 10 can be realized while the imaging quality of the optical system 10 is ensured.

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

1<f1/f<1.5；

f is the effective focal length of the optical system 10, and f1 is the effective focal length of the first lens L1.

Satisfying the above conditional expressions, by appropriately configuring the relationship between the effective focal length of the first lens L1 and the effective focal length of the optical system 10, the contribution amount of the first lens L1 to the total optical power of the optical system 10 is made appropriate, which is beneficial to improve the aberration correction capability of the optical system 10, and in addition, the first lens L1 can be matched with other lenses (the second lens L2 to the eighth lens L8) to enable the optical system 10 to have a better aberration correction effect, thereby ensuring that the optical system 10 has good imaging quality. When f1/f is less than or equal to 1, the effective focal length of the optical system 10 is too large, so that a larger field angle cannot be obtained, which is not favorable for high-resolution imaging of the optical system 10; when f1/f is greater than or equal to 1.5, the effective focal length of the first lens element L1 is too large, and the contribution to the total focal power of the optical system 10 is insufficient, so that the burden of the refractive power from the second lens element L2 to the eighth lens element L8 is increased, and the improvement of the aberration correction capability of the optical system 10 is not facilitated.

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

1<|R2+R3|/|R2-R3|<2.5；

r2 is the radius of curvature of the object-side surface S1 of the first lens element L1 at the optical axis 101, and R3 is the radius of curvature of the image-side surface S2 of the first lens element L2 at the optical axis 101.

The curvature change trends of the object side surface S1 and the image side surface S2 of the first lens L1 can be well controlled, so that the thickness ratio of the first lens L1 is gentle, the shape of the first lens L1 is further limited, the spherical aberration of the first lens L1 is favorably controlled, the imaging quality of a visual field on the optical axis 101 and the imaging quality of a visual field outside the optical axis 101 cannot be obviously degraded due to the change of the contribution of the spherical aberration, the optical performance of the optical system 10 is favorably improved, meanwhile, the change of the surface shape of the first lens L1 is gentle, the processing and manufacturing difficulty of the first lens L1 can be reduced, and the processing yield is improved.

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

1<SD42/SD41<1.2；

SD41 is half the maximum effective diameter of the object-side surface S7 of the fourth lens L4, and SD42 is half the maximum effective diameter of the image-side surface S8 of the fourth lens L4.

By satisfying the conditional expressions, the aperture of the object-side surface S7 of the fourth lens L4 and the aperture of the image-side surface S8 of the fourth lens L4 can be reasonably arranged, and the radial size of the fourth lens L4 is reduced, which is favorable for the optical system 10 to realize a small-head design. When the optical system 10 is applied to an electronic device, the size of the opening of the optical system 10 on the screen of the electronic device can be reduced, and the screen occupation ratio of the electronic device is further improved. In addition, when the above relation is satisfied, the edge size of the fourth lens L4 does not change too drastically, so that the workability of the lens is improved, and the larger aperture of the fourth lens L4 is also advantageous for enlarging the aperture, maintaining the amount of light transmitted through the optical system 10, and thus providing the optical system 10 with higher image quality. When the ratio SD41/SD42 is less than or equal to 1, the deflection degree of the incident light in the fourth lens L4 is too large, the off-axis aberration is easy to increase, and the imaging quality of the optical system 10 is reduced; when SD41/SD42 is 1.5 or more, the radial dimension of the fourth lens L4 becomes too large, and it becomes difficult to realize a small head design of the optical system 10.

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

5<f7/CT7<10.5；

f7 is the effective focal length of the seventh lens L7, and CT7 is the thickness of the seventh lens L7 on the optical axis 101.

By satisfying the conditional expression, the tolerance sensitivity of the center thickness of the seventh lens L7 can be reduced, the processing difficulty of the seventh lens L7 is reduced, the improvement of the assembly yield of the optical system 10 is facilitated, the production cost is further reduced, and by satisfying the relational expression, the excessive effective focal length of the seventh lens L7 and the difficult correction astigmatism generated by the optical system 10 can be avoided, so that the imaging quality of the optical system 10 is improved, meanwhile, the excessive center thickness of the seventh lens L7 can be avoided, and the miniaturization design of the optical system 10 is facilitated. When f7/CT7 is not more than 5, or f7/CT7 is not less than 10.5, tolerance sensitivity of the center thickness of the seventh lens L7 is high, processing difficulty of the seventh lens L7 is increased, assembly yield of the optical system 10 is not improved, and production cost is further increased.

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

6.2mm<f*tan(HFOV)<6.7mm；

f is the effective focal length of the optical system 10 and the HFOV is half the maximum field of view of the optical system 10.

The conditional expression is satisfied, the relationship between the total effective focal length of the optical system 10 and the maximum field angle of the optical system 10 is reasonably set, which is beneficial to enlarging the field angle of the optical system 10 to realize the wide-angle characteristic, so that the optical system can acquire more scene contents, and the distortion of the optical system 10 can be further suppressed by the proper effective focal length, thereby improving the imaging quality of the optical system 10, and meanwhile, the relational expression is satisfied, which is also beneficial to enlarging the imaging circle to realize the large image plane characteristic, thereby enriching the imaging information of the optical system 10, in addition, the total length of the optical system 10 is beneficial to being shortened, and the miniaturization design is realized. Therefore, the optical system 10 can be designed to be compact, and is advantageous for achieving high-pixel and large-image-plane characteristics of the optical system 10, thereby improving the imaging effect and the imaging quality.

The value of the effective focal length in the above relations is 546nm, the effective focal length is at least the value of the corresponding lens at the paraxial region 101, and the refractive power of the lens is at least the value of the effective focal length at the paraxial region 101. And the above relationship conditions and the technical effects thereof are directed to the optical system 10 having the above lens design. When the lens design (the number of lenses, the refractive power arrangement, the surface type arrangement, etc.) of the optical system 10 cannot be ensured, it is difficult to ensure that the optical system 10 can still have the corresponding technical effect when the relational expressions are satisfied, and even the imaging performance may be significantly reduced.

In some embodiments, at least one lens in the optical system 10 may have a spherical surface shape, and the design of the spherical surface shape may reduce the difficulty and cost of manufacturing the lens. In some embodiments, at least one lens of the optical system 10 may also have an aspheric surface, which may be referred to as having an aspheric surface when at least one side surface (object side surface or image side surface) of the lens is aspheric. In one embodiment, both the object-side surface and the image-side surface of each lens can be designed to be aspheric. The aspheric design can help the optical system 10 to eliminate aberration more effectively, improving imaging quality. In some embodiments, the design of each lens surface in the optical system 10 may be configured by spherical and aspherical surface types in order to take into account the manufacturing cost, the manufacturing difficulty, the imaging quality, the assembly difficulty, and the like.

The surface shape of the aspheric surface can be calculated by referring to an aspheric surface formula:

where Z is a distance from a corresponding point on the aspheric surface to a tangent plane of the aspheric surface at the optical axis 101, r is a distance from the corresponding point on the aspheric surface to the optical axis 101, c is a curvature of the aspheric surface at the optical axis 101, k is a conic coefficient, and Ai is a high-order term coefficient corresponding to the ith high-order term in the aspheric surface type formula.

It should also be noted that when a lens surface is aspheric, there may be points of inflection where the surface will change in shape in the radial direction, such as where one lens surface is convex near the optical axis 101 and concave near the maximum effective aperture. The planar design of the reverse curvature point can realize good correction on field curvature and distortion aberration of the edge field in the optical system 10, and improve imaging quality.

In some embodiments, at least one lens of the optical system 10 is made of Glass (GL). For example, the first lens L1 closest to the object side may be made of glass, and the effect of the glass material of the first lens L1 on eliminating temperature drift may be utilized to effectively reduce the influence of the environmental temperature change on the optical system 10, thereby maintaining a better and more stable imaging quality. In some embodiments, the material of at least one lens in the optical system 10 may also be Plastic (PC), and the Plastic material may be polycarbonate, gum, etc. The lens made of plastic can reduce the production cost of the optical system 10, and the lens made of glass can endure higher or lower temperature and has excellent optical effect and better stability. In some embodiments, lenses of different materials may be disposed in the optical system 10, that is, a design combining a glass lens and a plastic lens may be adopted, but the specific configuration relationship may be determined according to practical requirements and is not exhaustive here.

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 also 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 also be used.

In some embodiments, the optical system 10 further includes an aperture stop STO, which may also be a field stop, for controlling the light incident amount and the depth of field of the optical system 10, and achieving good interception of the ineffective light to improve the imaging quality of the optical system 10, and the aperture stop STO may be disposed between the object side of the optical system 10 and the object side surface S1 of the first lens L1. It is understood that, in other embodiments, the stop STO may also be disposed between two adjacent lenses, for example, between the third lens L3 and the fourth lens L4, or between the fourth lens L4 and the fifth lens L5, and the arrangement is adjusted according to practical situations, which is not specifically limited in this embodiment of the present application. The aperture stop STO may also be formed by a holder that holds the lens.

The optical system 10 of the present application is illustrated by the following more specific examples:

first embodiment

Referring to fig. 1, in the first embodiment, the optical system 10 includes, in order from an object side to an image side along an optical axis 101, an aperture 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 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. The respective lens surface types of the optical system 10 are as follows:

the object-side surface S1 of the first lens element L1 is convex at the paraxial region 101, and the image-side surface S2 is concave at the paraxial region 101;

the object-side surface S3 of the second lens element L2 is convex at the paraxial region 101, and the image-side surface S4 is concave at the paraxial region 101;

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

the object-side surface S7 of the fourth lens element L4 is convex at the paraxial region 101, and the image-side surface S8 is concave at the paraxial region 101;

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

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

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

the object-side surface S15 of the eighth lens element L8 is convex at the paraxial region 101, and the image-side surface S16 is concave at the paraxial region 101.

In the first embodiment, each of the first lens L1 to the eighth lens L8 has an aspheric surface, and each of the first lens L1 to the eighth lens L8 is made of Plastic (PC). The optical system 10 further includes a filter 110, the filter 110 can be a part of the optical system 10 or can be removed from the optical system 10, but when the filter 110 is removed, the total optical length TTL of the optical system 10 remains unchanged; in the embodiment, the optical filter 110 is an infrared cut-off filter, and the infrared cut-off filter is disposed between the image side surface S16 of the eighth lens L8 and the imaging surface S19 of the optical system 10, so as to filter out light rays in invisible wave bands such as infrared light, and only allow visible light to pass through, so as to obtain a better image effect; it is understood that the filter 110 can also filter out light in other bands, such as visible light, and only let infrared light pass through, and the optical system 10 can be used as an infrared optical lens, that is, the optical system 10 can also image and obtain better image effect in a dark environment and other special application scenes.

The lens parameters of the optical system 10 in the first embodiment are shown in table 1 below. The elements from the object side to the image side of the optical system 10 are arranged in the order from top to bottom in table 1, wherein the stop represents the aperture stop STO. The Y radius in table 1 is the radius of curvature of the corresponding surface of the lens at the optical axis 101. In table 1, the surface with the surface number S1 represents the object-side surface of the first lens L1, the surface with the surface number S2 represents the image-side surface of the first lens L1, and so on. The absolute value of the first value of the lens in the "thickness" parameter list is the thickness of the lens on the optical axis 101, and the absolute value of the second value is the distance from the image-side surface of the lens to the next optical surface (the object-side surface or stop surface of the next lens) on the optical axis 101, wherein the stop thickness parameter represents the distance from the stop surface to the object-side surface of the adjacent lens on the image side on the optical axis 101. In the table, the reference wavelength of the refractive index and abbe number of each lens is 587.6nm, the reference wavelength of the focal length (effective focal length) is 546nm, and the numerical units of the Y radius, thickness, and focal length (effective focal length) are millimeters (mm). In addition, the parameter data and the lens surface shape structure used for the relational expression calculation in the following embodiments are subject to the data in the lens parameter table in the corresponding embodiment.

TABLE 1

As can be seen from table 1, the effective focal length f of the optical system 10 in the first embodiment is 7.059mm, the f-number FNO is 2.45, the total optical length TTL is 8.864mm, the total optical length TTL in the following embodiments is the sum of the thickness values corresponding to surface numbers S1 to S17, and half of the maximum field angle HFOV of the optical system 10 is 42.789 °, which indicates that the optical system 10 in this embodiment has a large field angle.

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

TABLE 2

Further, in the first embodiment, the optical system 10 satisfies the following relationships:

f tan (hfov) ═ 6.534; satisfying the conditional expression, by reasonably setting the correlation between the total effective focal length of the optical system 10 and the maximum field angle of the optical system 10, it is beneficial to realize the characteristics of high pixel and large image plane of the optical system 10, so as to improve the shooting effect and improve the imaging quality.

f FNO/T45 ═ 9.892; by satisfying the conditional expressions, the optical system 10 not only can realize a miniaturized design, but also can ensure a sufficient amount of light transmission to satisfy the imaging requirements of the optical system 10 for high image quality and high definition.

∑CT/T1＝5.613；

By satisfying the conditional expressions, the total length of the optical system 10 can be effectively shortened and the imaging quality of the optical system 10 can be ensured by adjusting the proportional relationship between the total lens thickness of the first lens L1 to the eighth lens L8 on the optical axis 101 and the thickness of the first lens L1 on the optical axis 101, and the design requirement of miniaturization of the optical system 10 can be realized while the imaging quality of the optical system 10 is ensured.

f1/f is 1.109; satisfying the above conditional expressions, the relationship between the focal length of the first lens L1 and the effective focal length of the optical system 10 is reasonably configured, which is beneficial to improve the aberration correction capability of the optical system 10, and in addition, the first lens L1 can be matched with other lenses (the second lens L2 to the eighth lens L8) to enable the optical system 10 to have a better aberration correction effect, thereby ensuring that the optical system 10 has good imaging quality.

L R2+ R3 l/l R2-R3 l 1.581; satisfying the above conditional expressions, the aspect ratio of the object-side surface S1 and the image-side surface S2 of the first lens L1 can be well controlled, and further the shape of the first lens L1 is limited, which is beneficial to controlling the spherical aberration of the first lens L1, so that the imaging quality of the field of view on the optical axis 101 and the field of view outside the optical axis 101 will not be significantly degraded due to the change of the contribution of the spherical aberration, and is also beneficial to improving the optical performance of the optical system 10 and reducing the processing difficulty of the first lens L1.

SD42/SD41 is 1.126; by satisfying the conditional expressions, the aperture of the object-side surface S7 of the fourth lens L4 and the aperture of the image-side surface S8 of the fourth lens L4 can be reasonably arranged, and the radial dimension of the fourth lens L4 is reduced, so that the optical system 10 can be designed to have a small head. When the optical system 10 is applied to an electronic device, the size of the opening of the optical system 10 on the screen of the electronic device can be reduced, and the screen occupation ratio of the electronic device is further improved. Further, when the above-described relational expression is satisfied, the fourth lens L4 is high in workability, and is also advantageous in enlarging the aperture, maintaining the L4 with a good light transmission amount, and further enabling the L4 to have a high imaging quality.

f7/CT7 is 7.200; by satisfying the conditional expression, the tolerance sensitivity of the center thickness of the seventh lens L7 can be reduced, the processing difficulty of the seventh lens L7 is reduced, the improvement of the assembly yield of the optical system 10 is facilitated, the production cost is further reduced, and by satisfying the relational expression, the excessive focal length of the seventh lens L7 and the difficult astigmatism generated by the optical system 10 can be avoided, so that the imaging quality of the optical system 10 is reduced, and meanwhile, the excessive center thickness of the seventh lens L7 can be avoided, which is not favorable for the miniaturization design of the optical system 10.

f/FNO is 2.881; by satisfying the conditional expressions, when the ratio of the effective focal length of the optical system 10 to the f-number of the optical system 10 is controlled to be within the above range, the optical system 10 can obtain a longer focal length while satisfying miniaturization, and at the same time, the optical system 10 can obtain a sufficient amount of light transmission during shooting, so that the optical system 10 can obtain an imaging effect with high image quality and high definition.

Σ CT/Σ AT 1.835; by satisfying the conditional expression, by controlling the ratio of the total of the lens thicknesses of the first lens L1 to the eighth lens L8 on the optical axis 101 to the total of the spacing distances of the adjacent two lenses of the first lens L1 to the eighth lens L8 on the optical axis 101, the processing and the assembly of each lens of the system are facilitated, the total length of the optical system 10 can be effectively reduced and ensured, and the miniaturization of the optical system 10 is facilitated.

Fig. 2 includes a longitudinal spherical aberration diagram, an astigmatism diagram, and a distortion diagram of the optical system 10 in the first embodiment. Wherein the reference wavelength of the astigmatism and distortion plots is 546 nm. Longitudinal Spherical Aberration diagrams (Longitudinal Spherical Aberration) show the convergent focus deviation of light rays of different wavelengths through the lens. The ordinate of the longitudinal spherical aberration diagram represents Normalized Pupil coordinates (Normalized Pupil Coordinator) from the Pupil center to the Pupil edge, and the abscissa represents the distance (in mm) from the imaging plane S19 to the intersection point of the ray and the optical axis. It can be known from the longitudinal spherical aberration diagram that the convergent focus deviation degrees of the light rays with the wavelengths in the first embodiment tend to be consistent, the maximum focus deviation of the reference wavelengths is controlled within ± 0.02mm, and for a large image plane system, the diffuse spots or the chromatic halo in an imaging picture are effectively suppressed. FIG. 2 also includes an astigmatism plot of the Field curvature (effective Field curvatures) of optical system 10, where the S curve represents the sagittal Field curvature at 546nm and the T curve represents the meridional Field curvature at 546 nm. As can be seen from the figure, the field curvature of the optical system 10 is small, the maximum field curvature is controlled within ± 0.2mm, for a large image plane system, the degree of image plane curvature is effectively suppressed, the sagittal field curvature and the meridional field curvature under each field tend to be consistent, and the astigmatism of each field is well controlled, so that it can be seen that the center to the edge of the field of view of the optical system 10 has clear imaging. Further, it is understood from the distortion map that the degree of distortion of the optical system 10 having a large image plane characteristic is also well controlled.

Second embodiment

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

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

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

The lens parameters of the optical system 10 are given in tables 3 and 4, wherein the definitions of the names and parameters of the elements can be obtained from the first embodiment, which is not repeated herein.

TABLE 3

TABLE 4

As can be seen from the aberration diagrams in fig. 4, the longitudinal spherical aberration, curvature of field, astigmatism, and distortion of the optical system 10 having the wide-angle characteristic are all controlled well, and the optical system 10 of this embodiment can have good imaging quality.

Third embodiment

Referring to fig. 5, in the third embodiment, the optical system 10 includes, in order from the object side to the image side along the optical axis 101, an aperture stop STO, the first lens element L1 with positive refractive power, the second lens element L2 with negative refractive power, the third lens element L3 with positive refractive power, the fourth lens element L4 with negative refractive power, the fifth lens element L5 with positive refractive power, the sixth lens element L6 with negative refractive power, the seventh lens element L7 with positive refractive power, and the eighth lens element L8 with negative refractive power. The respective lens surface types of the optical system 10 are as follows:

the object-side surface S7 of the fourth lens element L4 is concave at the paraxial region 101, and the image-side surface S8 is concave at the paraxial region 101;

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

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

The lens parameters of the optical system 10 in this embodiment are given in tables 5 and 6, wherein the definitions of the names and parameters of the elements can be obtained from the first embodiment, which is not repeated herein.

TABLE 5

TABLE 6

As can be seen from the aberration diagrams in fig. 6, the longitudinal spherical aberration, curvature of field, astigmatism, and distortion of the optical system 10 having the wide-angle characteristic are all controlled well, and the optical system 10 of this embodiment can have good imaging quality.

Fourth embodiment

Referring to fig. 7, in the fourth embodiment, the optical system 10 includes, in order from the object side to the image side along the optical axis 101, an aperture stop STO, the first lens element L1 with positive refractive power, the second lens element L2 with negative refractive power, the third lens element L3 with positive refractive power, the fourth lens element L4 with negative refractive power, the fifth lens element L5 with positive refractive power, the sixth lens element L6 with negative refractive power, the seventh lens element L7 with positive refractive power, and the eighth lens element L8 with negative refractive power. The respective lens surface types of the optical system 10 are as follows:

The lens parameters of the optical system 10 in this embodiment are given in tables 7 and 8, wherein the definitions of the names and parameters of the elements can be obtained from the first embodiment, which is not repeated herein.

TABLE 7

TABLE 8

As can be seen from the aberration diagrams in fig. 8, the longitudinal spherical aberration, curvature of field, astigmatism, and distortion of the optical system 10 having wide-angle characteristics are well controlled, and the optical system 10 of this embodiment can have good imaging quality.

Fifth embodiment

Referring to fig. 9, in the fifth embodiment, the optical system 10 includes, in order from the object side to the image side along the optical axis 101, an aperture stop STO, the first lens element L1 with positive refractive power, the second lens element L2 with negative refractive power, the third lens element L3 with positive refractive power, the fourth lens element L4 with negative refractive power, the fifth lens element L5 with positive refractive power, the sixth lens element L6 with negative refractive power, the seventh lens element L7 with positive refractive power, and the eighth lens element L8 with negative refractive power. The respective lens surface types of the optical system 10 are as follows:

the object-side surface S7 of the fourth lens element L4 is concave at the paraxial region 101, and the image-side surface S8 is convex at the paraxial region 101;

The lens parameters of the optical system 10 in this embodiment are given in tables 9 and 10, wherein the definitions of the names and parameters of the elements can be obtained from the first embodiment, which is not repeated herein.

TABLE 9

Watch 10

As can be seen from the aberration diagrams in fig. 10, the longitudinal spherical aberration, curvature of field, astigmatism, and distortion of the optical system 10 having the wide-angle characteristic are all controlled well, and the optical system 10 of this embodiment can have good imaging quality.

Referring to table 11, table 11 summarizes ratios of the relations in the first embodiment to the fifth embodiment of the present application.

TABLE 11

Relation/embodiment	First embodiment	Second embodiment	Third embodiment	Fourth embodiment	Fifth embodiment
						f tan (HFOV) (unit: mm)	6.534	6.306	6.344	6.327	6.490
f*FNO/T45	9.892	11.369	12.568	12.722	12.763
						∑CT/CT1	5.613	10.822	7.339	5.657	6.176
f1/f	1.095	1.124	1.159	1.395	1.372
						\|R2+R3\|/\|R2-R3\|	1.581	1.418	1.675	2.262	2.441
f7/CT7	7.200	5.055	10.274	6.871	7.108
						f/Fno (unit: mm)	2.881	2.991	2.867	2.947	2.903
∑CT/ΣAT	1.835	2.012	1.630	2.392	2.302
						1<SD42/SD41<1.2	1.126	1.098	1.122	1.127	1.136

The optical system 10 in the above embodiments can keep good imaging quality while compressing the overall length to achieve a compact design, and can also have a larger field of view range, compared to a general optical system.

Referring to fig. 11, an embodiment of the present application further provides a camera module 20, where the camera module 20 includes an optical system 10 and a photosensitive chip 210, and the photosensitive chip 210 is disposed on an image side of the optical system 10, and the photosensitive chip 210 and the optical system can be fixed by a bracket. The photosensitive chip 210 may be a CCD (Charge Coupled Device) or a CMOS (Complementary Metal Oxide Semiconductor) sensor. Generally, the image forming surface S19 of the optical system 10 overlaps the photosensitive surface of the photosensitive chip 210 when assembled. By adopting the optical system 10, the camera module 20 can realize large image plane characteristics, large aperture characteristics and a miniaturized design, and can meet the requirements of large-range shooting and high imaging quality.

Referring to fig. 12, some embodiments of the present application also provide an electronic device 30. The electronic device 30 includes a fixing member 310, the camera module 20 is mounted on the fixing member 310, and the fixing member 310 may be a display screen, a circuit board, a middle frame, a rear cover, or the like. The electronic device 30 may be, but is not limited to, a mobile phone, a video phone, a smart phone, an e-book reader, a tablet computer, a vehicle-mounted camera such as a PDA (Personal Digital Assistant) or a car-recorder, or a wearable device such as a smart watch or smart glasses. The camera module 20 can realize large image plane characteristics, large aperture characteristics and miniaturization design, so that the electronic device 30 can meet the requirements of large-range shooting and high imaging quality, and can also realize portable design.

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 to implicitly indicate the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of the present invention, "a plurality" means two or more unless specifically defined 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; the connection can be mechanical connection, electrical connection or communication; either directly or indirectly through intervening media, either internally or in any other relationship. 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 description herein, references to the description of the term "one embodiment," "some embodiments," "an example," "a specific example," or "some examples," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, the schematic representations of the terms used above are not necessarily intended to refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, various embodiments or examples and features of different embodiments or examples described in this specification can be combined and combined by one skilled in the art without contradiction.

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

Claims

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

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

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

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

a fourth lens element with refractive power;

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

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

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

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

the optical system satisfies the relationship:

1.6<∑CT/ΣAT<2.4；

Σ CT is the sum of the lens thicknesses of the first lens to the eighth lens on the optical axis, and Σ AT is the sum of the intervals between two adjacent lenses of the first lens to the eighth lens on the optical axis.

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

9.5< f FNO/T45< 13; and/or the presence of a gas in the gas,

2.8mm<f/FNO<3mm；

f is an effective focal length of the optical system, FNO is an f-number of the optical system, and T45 is a distance on an optical axis from an object side surface of the fourth lens to an image side surface of the fifth lens.

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

5.5<∑CT/CT1<11；

CT1 is the thickness of the first lens on the optical axis.

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

1<f1/f<1.5；

f1 is the effective focal length of the first lens.

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

1<|R2+R3|/|R2-R3|<2.5；

r2 is a radius of curvature of an object-side surface of the first lens at an optical axis, and R3 is a radius of curvature of an image-side surface of the first lens at the optical axis.

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

1<SD42/SD41<1.2；

SD41 is half the maximum effective aperture of the object-side surface of the fourth lens, and SD42 is half the maximum effective aperture of the image-side surface of the fourth lens.

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

5<f7/CT7<10.5；

f7 is the effective focal length of the seventh lens, and CT7 is the thickness of the seventh lens on the optical axis.

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

6.2mm<f*tan(HFOV)<6.7mm；

the HFOV is half of the maximum field angle of the optical system.

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

10. An electronic device, comprising a fixing member and the camera module set according to claim 10, wherein the camera module set is disposed on the fixing member.