CN113835199A

CN113835199A - Optical imaging system

Info

Publication number: CN113835199A
Application number: CN202111201867.XA
Authority: CN
Inventors: 高扬; 徐武超; 戴付建; 赵烈烽
Original assignee: Zhejiang Sunny Optics Co Ltd
Current assignee: Zhejiang Sunny Optics Co Ltd
Priority date: 2021-10-15
Filing date: 2021-10-15
Publication date: 2021-12-24

Abstract

The invention discloses an optical imaging system, which sequentially comprises the following components from an object side to an image side along an optical axis: a first lens; a second lens having a negative optical power; a third lens; a fourth lens element having a concave image-side surface; a fifth lens; a sixth lens having a negative optical power; a seventh lens element having a convex object-side surface and a concave image-side surface; and an eighth lens element; wherein, the on-axis distance TTL from the object side surface of the first lens to the imaging surface and the half of the diagonal length ImgH of the effective pixel area on the imaging surface satisfy: TTL/ImgH ≦ 1.4. The optical imaging system can have good imaging quality by defining the focal power and the surface type of the second lens, the fourth lens, the fifth lens and the seventh lens; by restricting the ratio of the on-axis distance from the object side surface of the first lens to the imaging surface to half of the diagonal length of the effective pixel area on the imaging surface, the optical imaging system is ultrathin and has high pixels.

Description

Optical imaging system

Technical Field

The invention belongs to the field of optical imaging, and particularly relates to an optical imaging system comprising eight lenses.

Background

The smart phone drives the performance of the image system to be greatly improved, and the life of people is greatly changed. In order to continuously improve the imaging quality, more improvements are applied to optical imaging systems with small structures. At present, the image plane size of a mobile phone imaging system is on the trend of continuous increase, and the optical lens generally satisfies the requirements by increasing the number of lenses, but the requirements are opposite to the requirements of a miniaturized structure required by a smart phone. The conventional lens mounted on a portable electronic product mostly adopts a three-piece or four-piece lens structure, and the existing optical system cannot meet the requirement of a higher-order photographing system. With the development of technology and the increasing demand of diversified users, five-lens, six-lens and seven-lens structures are gradually emerging in the design of optical imaging systems to achieve better imaging quality.

In order to simultaneously require miniaturization and lightness as much as possible and enable the imaging effect of the optical lens to meet the requirements, higher difficulty and challenge are brought to the lens design. Therefore, it is a problem to be solved how to select a suitable material, a reasonable lens refractive index configuration and shape, and finally make the lens assembly become an ultra-thin and high-resolution lens assembly.

This application technical scheme has obtained good image quality through 8 lens focal powers of rational distribution, simultaneously through the introduction of first GM mould pressing material, has reduced the total length of system, has satisfied frivolous, miniaturized requirement.

Disclosure of Invention

The application aims at providing an optical imaging system consisting of eight lenses, which has the characteristics of ultra-thin and good imaging quality.

The present application provides an optical imaging system, in order from an object side to an image side along an optical axis, comprising:

a first lens;

a second lens having a negative optical power;

a third lens;

a fourth lens element having a concave image-side surface;

a fifth lens;

a sixth lens having a negative optical power;

a seventh lens element having a convex object-side surface and a concave image-side surface;

an eighth lens;

wherein, the on-axis distance TTL from the object side surface of the first lens to the imaging surface and the half of the diagonal length ImgH of the effective pixel area on the imaging surface satisfy: TTL/ImgH ≦ 1.4.

According to one embodiment of the present application, the effective focal length f1 of the first lens, the effective focal length f7 of the seventh lens, and half of the maximum field angle Semi-FOV of the optical imaging system satisfy: 1.0 ≦ f7/f × tan (Semi-FOV) ≦ 1.2.

According to one embodiment of the present application, the central thickness CT1 of the first lens on the optical axis, the central thickness CT2 of the second lens on the optical axis, the central thickness CT3 of the third lens on the optical axis, the air interval T34 of the third lens and the fourth lens on the optical axis, and the distance BFL from the image side surface of the last lens of the optical imaging system to the imaging surface on the optical axis satisfy: 0.5 ≦ (CT1+ CT2+ CT3-T34)/BFL ≦ 1.2.

According to one embodiment of the present application, a radius of curvature R13 of the seventh lens object-side surface and a radius of curvature R14 of the seventh lens image-side surface satisfy: 16 ≦ f7/R13+ f7/R14 ≦ 20.

According to one embodiment of the present application, a radius of curvature R13 of the seventh lens object-side surface and a radius of curvature R14 of the seventh lens image-side surface satisfy: 1.5 ≦ (R13+ R14)/(R13-R14) | ≦ 3.5.

According to an embodiment of the present application, the effective focal length f7 of the seventh lens and the effective focal length f8 of the eighth lens satisfy: 0.5 ≦ f7/f8| ≦ 1.5.

According to one embodiment of the present application, the radius of curvature R3 of the object-side surface of the second lens and the radius of curvature R4 of the image-side surface of the second lens satisfy: 1.4 ≦ R3/R4 ≦ 1.7.

According to one embodiment of the present application, the effective focal length f5 of the fifth lens, the effective focal length f6 of the sixth lens, and the effective focal length f of the optical imaging system satisfy: 0.5 ≦ (f5+ f6)/f | ≦ 5.7.

According to one embodiment of the present application, the combined focal length f234 of the second, third, and fourth lenses satisfies: -4.0 ≦ f234/f ≦ -2.0.

According to an embodiment of the present application, a sum Σ AT of an on-axis distance TTL from an object-side surface of the first lens to an imaging plane and an air interval on an optical axis between the first lens and any adjacent two lenses having optical powers in a lens closest to the imaging plane satisfies: 2.5 ≦ TTL/Σ AT ≦ 3.0.

According to one embodiment of the present application, the effective focal length f1 of the first lens and the effective focal length f4 of the fourth lens satisfy: 2.0 ≦ f4/f1| ≦ 3.5.

According to one embodiment of the present application, an on-axis distance SL from the diaphragm to the imaging surface and an on-axis distance BFL from the image-side surface of the last lens of the optical imaging system to the imaging surface satisfy: 6.5 ≦ SL/BFL ≦ 8.5.

According to one embodiment of the application, the combined focal length f4567 of the fourth, fifth, sixth, and seventh lenses satisfies: 1.0 ≦ f4567/f ≦ 1.5.

The present application further provides an optical imaging system, in order from an object side to an image side along an optical axis, comprising:

a first lens;

a second lens having a negative optical power;

a third lens;

a fourth lens;

a fifth lens element having a convex object-side surface and a convex image-side surface;

a sixth lens having a negative optical power;

a seventh lens;

an eighth lens element having a convex object-side surface and a concave image-side surface;

The invention has the beneficial effects that:

the optical imaging system provided by the invention comprises a plurality of lenses, such as a first lens to an eighth lens. The optical imaging system can have good imaging quality by defining the focal power and the surface type of the second lens, the fourth lens, the fifth lens and the seventh lens; by restricting the ratio of the on-axis distance from the object side surface of the first lens to the imaging surface to half of the diagonal length of the effective pixel area on the imaging surface, the optical imaging system is ultrathin and has high pixels.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings needed to be used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art to obtain other drawings based on these drawings without creative efforts.

FIG. 1 is a schematic diagram of a lens assembly of an optical imaging system 1 according to an embodiment of the present invention;

FIGS. 2a and 2b are axial chromatic aberration curves and astigmatic curves of an optical imaging system of example 1 of the present invention, respectively;

FIG. 3 is a schematic diagram of a lens assembly of an optical imaging system according to embodiment 2 of the present invention;

FIGS. 4a and 4b are axial chromatic aberration curves and astigmatic curves, respectively, of an optical imaging system of example 2 of the present invention;

FIG. 5 is a schematic diagram of a lens assembly of an optical imaging system according to embodiment 3 of the present invention;

FIGS. 6a and 6b are axial chromatic aberration curves and astigmatism curves, respectively, of an optical imaging system in accordance with embodiment 3 of the present invention;

FIG. 7 is a schematic diagram of a lens assembly of an optical imaging system according to embodiment 4 of the present invention;

FIGS. 8a and 8b are axial chromatic aberration curves and astigmatism curves, respectively, of an optical imaging system in accordance with embodiment 4 of the present invention;

FIG. 9 is a schematic diagram of a lens assembly of an optical imaging system according to embodiment 5 of the present invention;

FIGS. 10a and 10b are axial chromatic aberration curves and astigmatism curves, respectively, of an optical imaging system in accordance with embodiment 5 of the present invention;

FIG. 11 is a schematic diagram of a lens assembly of an optical imaging system according to embodiment 6 of the present invention;

fig. 12a and 12b are axial chromatic aberration curves and astigmatism curves of example 6 of the optical imaging system of the present invention, respectively.

Detailed Description

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

It should be noted that in this specification, the expressions first, second, third, etc. are used only to distinguish one feature from another, and do not represent any limitation on the features. Thus, the first lens discussed below may also be referred to as the second lens or the third lens without departing from the teachings of the present invention.

It will be further understood that the terms "comprises," "comprising," "has," "having," "includes" and/or "including," when used in this specification, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof. Moreover, when a statement such as "at least one of" appears after a list of listed features, the entirety of the listed features is modified rather than modifying individual elements in the list. Furthermore, when describing embodiments of the present application, the use of "may" mean "one or more embodiments of the present application. Also, the term "exemplary" is intended to refer to an example or illustration.

In the drawings, the thickness, size, and shape of the lens have been slightly exaggerated for convenience of explanation. In particular, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shape of the spherical surface or the aspherical surface is not limited to the shape of the spherical surface or the aspherical surface shown in the drawings. The figures are purely diagrammatic and not drawn to scale.

In the description of the present invention, the paraxial region refers to a region near the optical axis. If the lens surface is convex and the convex position is not defined, it means that the lens surface is convex at least in the paraxial region. If the lens surface is concave and the concave position is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is called the object side surface of the lens, and the surface of each lens closest to the imaging surface is called the image side surface of the lens.

Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. Features, principles and other aspects of the present invention will be described in detail below with reference to the accompanying drawings in conjunction with embodiments.

Exemplary embodiments

The optical imaging system according to an exemplary embodiment of the present invention includes eight lenses, in order from an object side to an image side along an optical axis: the lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens, wherein the second lens has negative focal power; the image side surface of the fourth lens is a concave surface; the sixth lens has negative focal power; the object side surface of the seventh lens element is convex, and the image side surface of the seventh lens element is concave. The optical imaging system can have good imaging quality by defining the optical power and the surface type of the second lens, the fourth lens, the fifth lens and the seventh lens.

The optical imaging system according to still another exemplary embodiment of the present invention includes eight lenses, in order from an object side to an image side along an optical axis: the lens comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens, wherein the second lens has negative focal power; the object side surface of the fifth lens is a convex surface, and the image side surface of the fifth lens is a convex surface; the sixth lens has negative focal power; the object side surface of the eighth lens element is convex, and the image side surface of the eighth lens element is concave. The optical imaging system can have good imaging quality by limiting the optical power and the surface type of the second lens, the fifth lens, the sixth lens and the eighth lens.

In the present exemplary embodiment, the on-axis distance TTL from the object-side surface of the first lens to the imaging plane and the half ImgH of the diagonal length of the effective pixel area on the imaging plane satisfy: TTL/ImgH ≦ 1.4. By restricting the ratio of the on-axis distance from the object side surface of the first lens to the imaging surface to half of the diagonal length of the effective pixel area on the imaging surface, the optical imaging system is ultrathin and has high pixels. More specifically, the on-axis distance TTL from the object-side surface of the first lens to the imaging surface and the half ImgH of the diagonal length of the effective pixel area on the imaging surface satisfy: TTL/ImgH ≦ 1.35.

In the present exemplary embodiment, the effective focal length f1 of the first lens, the effective focal length f7 of the seventh lens, and half of the maximum field angle Semi-FOV of the optical imaging system satisfy: 1.0 ≦ f7/f × tan (Semi-FOV) ≦ 1.2. The chip matched with the large image plane can be ensured by the effective focal length of the first lens, the effective focal length of the seventh lens and half of the maximum field angle of the optical imaging system, so that the system has the characteristics of high pixel, low sensitivity and easiness in processing. More specifically, the effective focal length f1 of the first lens, the effective focal length f7 of the seventh lens, and half of the maximum field angle Semi-FOV of the optical imaging system satisfy: 1.0 ≦ f7/f × tan (Semi-FOV) ≦ 1.18.

In the present exemplary embodiment, the central thickness CT1 of the first lens on the optical axis, the central thickness CT2 of the second lens on the optical axis, the central thickness CT3 of the third lens on the optical axis, the air interval T34 of the third lens and the fourth lens on the optical axis, and the distance BFL from the image-side surface of the last lens of the optical imaging system to the imaging surface on the optical axis satisfy: 0.5 ≦ (CT1+ CT2+ CT3-T34)/BFL ≦ 1.2. The air space of the third lens and the fourth lens on the optical axis is limited in a reasonable range with the ratio of the distance from the image side surface of the last lens of the optical imaging system to the imaging surface on the optical axis, so that the distortion contribution of the fourth lens is adjusted to compensate the distortion generated by the lens at the rear end close to the image surface. More specifically, the central thickness CT1 of the first lens on the optical axis, the central thickness CT2 of the second lens on the optical axis, the central thickness CT3 of the third lens on the optical axis, the air space T34 of the third lens and the fourth lens on the optical axis and the distance BFL from the image side surface of the last lens of the optical imaging system to the imaging surface on the optical axis satisfy: 0.75 ≦ (CT1+ CT2+ CT3-T34)/BFL ≦ 1.0.

In the present exemplary embodiment, the radius of curvature R13 of the object-side surface of the seventh lens and the radius of curvature R14 of the image-side surface of the seventh lens satisfy: 16 ≦ f7/R13+ f7/R14 ≦ 20. The focal power and the lens shape of the seventh lens can be controlled by controlling the ratio of the effective focal length of the seventh lens to the curvature radius of the object side surface of the seventh lens and the ratio of the effective focal length of the seventh lens to the curvature radius of the image side surface of the seventh lens, so that the processing requirement is met. More specifically, the radius of curvature R13 of the object-side surface of the seventh lens and the radius of curvature R14 of the image-side surface of the seventh lens satisfy: 17.45 ≦ f7/R13+ f7/R14 ≦ 19.30.

In the present exemplary embodiment, the radius of curvature R13 of the object-side surface of the seventh lens and the radius of curvature R14 of the image-side surface of the seventh lens satisfy: 1.5 ≦ (R13+ R14)/(R13-R14) | ≦ 3.5. By controlling the conditional expression within a reasonable range, the contribution rate of the third-order astigmatism of the fourth lens can be controlled to a certain degree, so that the third-order astigmatism of the fourth lens is within a reasonable range, and the effect of high macro resolution is achieved. More specifically, the radius of curvature R13 of the object-side surface of the seventh lens and the radius of curvature R14 of the image-side surface of the seventh lens satisfy: 2.30 ≦ (R13+ R14)/(R13-R14) | ≦ 3.40.

In the present exemplary embodiment, the effective focal length f7 of the seventh lens and the effective focal length f8 of the eighth lens satisfy: 0.5 ≦ f7/f8| ≦ 1.5. By reasonably controlling the focal length ratio of the seventh lens and the eighth lens within a certain range, the aberration generated by the seventh lens and the aberration generated by the eighth lens can be balanced, the contribution of the aberration of the lenses is controlled, the aberration of the system is in a reasonable horizontal state, and the optical imaging system has good imaging quality. More specifically, the effective focal length f7 of the seventh lens and the effective focal length f8 of the eighth lens satisfy: 1.24 ≦ f7/f8| ≦ 1.41.

In the present exemplary embodiment, the radius of curvature R3 of the object-side surface of the second lens and the radius of curvature R4 of the image-side surface of the second lens satisfy: 1.4 ≦ R3/R4 ≦ 1.7. By limiting the ratio range of the object side curvature radius and the image side curvature radius of the second lens, the shape of the second lens can be effectively constrained, so that the aberration contribution of the object side surface and the image side surface of the second lens can be effectively controlled, and the imaging quality of the system can be effectively improved. More specifically, the radius of curvature R3 of the object-side surface of the second lens and the radius of curvature R4 of the image-side surface of the second lens satisfy: 1.45 ≦ R3/R4 ≦ 1.65.

In the present exemplary embodiment, the effective focal length f5 of the fifth lens, the effective focal length f6 of the sixth lens, and the effective focal length f of the optical imaging system satisfy: 0.5 ≦ (f5+ f6)/f | ≦ 5.7. By reasonably controlling the ratio of the sum of the fifth lens and the sixth lens to the focal length of the system within a certain range, the aberration generated by the combination of the fifth lens and the sixth lens can be balanced, the contribution of the aberration of the lenses can be controlled, the aberration of the system can be in a reasonable horizontal state, and the optical imaging system has good imaging quality. More specifically, the effective focal length f5 of the fifth lens, the effective focal length f6 of the sixth lens, and the effective focal length f of the optical imaging system satisfy: 1.80 ≦ | (f5+ f6)/f | ≦ 5.65.

In the present exemplary embodiment, the combined focal length f234 of the second lens, the third lens, and the fourth lens satisfies: -4.0 ≦ f234/f ≦ -2.0. By reasonably controlling the ratio of the combined focal length of the second lens, the third lens and the fourth lens to the system focal length within a certain range, the aberration generated by the combination of the second lens, the third lens and the fourth lens can be balanced, the contribution of the lens aberration is controlled, the system aberration is in a reasonable horizontal state, and the optical imaging system has good imaging quality. More specifically, the combined focal length f234 of the second lens, the third lens and the fourth lens satisfies: -2.90 ≦ f234/f ≦ -2.10.

In the present exemplary embodiment, the on-axis distance TTL of the first lens object-side surface to the imaging plane and the sum Σ AT of the air intervals on the optical axis between the first lens and any adjacent two lenses having optical powers in the lens closest to the imaging plane satisfy: 2.5 ≦ TTL/Σ AT ≦ 3.0. The ratio of the distance from the object side surface of the first lens to the imaging surface on the axis to the sum of the air intervals on the optical axis between the first lens and any two adjacent lenses with focal power in the lens closest to the imaging surface is reasonably controlled in a certain reasonable range, so that the lens structure is more densely and reasonably arranged in a limited space size, and ultra-thinning and miniaturization are realized. More specifically, the on-axis distance TTL from the object-side surface of the first lens to the imaging plane and the sum Σ AT of the air intervals on the optical axis between the first lens and any adjacent two lenses having optical powers in the lens closest to the imaging plane satisfy: 2.51 ≦ TTL/Σ AT ≦ 2.95.

In the present exemplary embodiment, the effective focal length f1 of the first lens and the effective focal length f4 of the fourth lens satisfy: 2.0 ≦ f4/f1| ≦ 3.5. The ratio of the effective focal length of the fourth lens to the effective focal length of the first lens is reasonably controlled within a certain range, so that the reasonable distribution of the focal powers of the fourth lens and the first lens can be realized, the system aberration is reduced, and the imaging quality of the system is improved. More specifically, the effective focal length f1 of the first lens and the effective focal length f4 of the fourth lens satisfy: 2.1 ≦ f4/f1| ≦ 3.10.

In the present exemplary embodiment, the on-axis distance SL from the stop to the imaging surface and the distance BFL from the image-side surface of the last lens of the optical imaging system to the imaging surface on the optical axis satisfy: 6.5 ≦ SL/BFL ≦ 8.5. The ratio of the distance between the diaphragm and the imaging surface on the axis to the distance between the last lens image side surface of the optical imaging system and the imaging surface on the optical axis is reasonably controlled within a certain range, so that the aberration generated by the front and the back combination is balanced, the contribution of the aberration of the lens is controlled, the aberration of the system is in a reasonable horizontal state, and the optical imaging system has good imaging quality. More specifically, the axial distance SL from the diaphragm to the imaging surface and the axial distance BFL from the image side surface of the last lens of the optical imaging system to the imaging surface satisfy: 6.80 ≦ SL/BFL ≦ 7.80.

In the present exemplary embodiment, the combined focal length f4567 of the fourth lens, the fifth lens, the sixth lens, and the seventh lens satisfies: 1.0 ≦ f4567/f ≦ 1.5. By reasonably controlling the ratio of the combined focal length of the fourth lens to the seventh lens to the focal length of the system within a certain range, the aberration generated by the front and the rear combination can be balanced, the contribution of the aberration of the lenses is controlled, the aberration of the system is in a reasonable horizontal state, and the optical imaging system has good imaging quality. More specifically, the combined focal length f4567 of the fourth lens, the fifth lens, the sixth lens, and the seventh lens satisfies: 1.30 ≦ f4567/f ≦ 1.48.

In the present exemplary embodiment, the object-side surface and the image-side surface of any one of the first lens E1 through the eighth lens E8 are aspheric, and the profile x of each aspheric lens can be defined using, but not limited to, the following aspheric formula:

wherein x is the rise of the distance from the aspheric surface vertex to the aspheric surface vertex when the aspheric surface is at the position with the height of h along the optical axis direction; c is the paraxial curvature of the aspheric surface, c being 1/R (i.e., paraxial curvature c is the inverse of radius of curvature R in table 1); k is a conic coefficient; ai is the correction coefficient of the i-th order of the aspheric surface.

In the present exemplary embodiment, the above-described optical imaging system may further include a diaphragm. The stop may be disposed at an appropriate position as needed, for example, the stop may be disposed between the object and the first lens. Optionally, the optical imaging system may further include a filter for correcting color deviation and/or a protective glass for protecting the photosensitive element on the imaging surface.

The optical imaging system according to the above-described embodiment of the present invention may employ a plurality of lenses, for example, the above-described eight lenses. The optical imaging system has a large imaging image surface by reasonably distributing the focal power and the surface type of each lens, the central thickness of each lens, the on-axis distance between each lens and the like, has the characteristics of wide imaging range and high imaging quality, and ensures the ultrathin property of the mobile phone.

In an exemplary embodiment, at least one of the mirror surfaces of each lens is an aspheric mirror surface, i.e., at least one of the object side surface of the first lens to the image side surface of the eighth lens is an aspheric mirror surface. The aspheric lens is characterized in that: the aspherical lens has a better curvature radius characteristic, and has advantages of improving distortion aberration and astigmatic aberration, unlike a spherical lens having a constant curvature from the lens center to the lens periphery, in which the curvature is continuously varied from the lens center to the lens periphery. After the aspheric lens is adopted, the aberration generated during imaging can be eliminated as much as possible, thereby improving the imaging quality. Optionally, at least one of an object-side surface and an image-side surface of each of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens is an aspherical mirror surface. Optionally, each of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens has an object-side surface and an image-side surface which are aspheric mirror surfaces.

However, it will be appreciated by those skilled in the art that the number of lenses constituting the optical imaging system may be varied to achieve the various results and advantages described in the present specification without departing from the claimed subject matter. For example, although eight lenses are exemplified in the embodiment, the optical imaging system is not limited to include eight lenses, and the optical imaging system may include other numbers of lenses if necessary.

Specific embodiments of an optical imaging system suitable for use in the above-described embodiments are further described below with reference to the drawings.

Detailed description of the preferred embodiment 1

Fig. 1 is a schematic view of a lens assembly structure of an optical imaging system according to embodiment 1 of the present invention, the optical imaging system, in order from an object side to an image side along an optical axis, comprising: a stop STO, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, an eighth lens E8, a filter E9, and an image forming surface S19.

The first lens element E1 has positive power, and has a convex object-side surface S1 and a concave image-side surface S2. The second lens element E2 has negative power, and has a convex object-side surface S3 and a concave image-side surface S4. The third lens element E3 has positive power, and has a convex object-side surface S5 and a concave image-side surface S6. The fourth lens element E4 has negative power, and has a convex object-side surface S7 and a concave image-side surface S8. The fifth lens element E5 has positive power, and has a convex object-side surface S9 and a convex image-side surface S10. The sixth lens element E6 has negative power, and has a convex object-side surface S11 and a concave image-side surface S12. The seventh lens element E7 has positive power, and has a convex object-side surface S13 and a concave image-side surface S14. The eighth lens element E8 has negative power, and has a convex object-side surface S15 and a concave image-side surface S16. Filter E8 has an object side S17 and an image side S18. The light from the object sequentially passes through the respective surfaces S1 to S18 and is finally imaged on the imaging plane S19.

As shown in table 1, a basic parameter table of the optical imaging system of example 1 is shown, in which the units of the radius of curvature, the thickness, and the focal length are all millimeters (mm). The first lens E1 is preferably but not limited to GM material (mold glass), which has the characteristics of glass material, and is easy to manufacture aspheric lens, and is more advantageous for optimization.

TABLE 1

As shown in table 2, in embodiment 1, the total effective focal length f of the optical imaging system is 7.04mm, the distance TTL on the optical axis from the object side surface S1 of the first lens E1 to the imaging surface S19 of the optical imaging system is 8.80mm, and the half ImgH of the diagonal length of the effective pixel region on the imaging surface S19 is 7.40 mm. Half the maximum field angle Semi-FOV of the optical imaging system is 42.80 °. The aperture value Fno of the optical imaging system is 1.68.

TABLE 2

The optical imaging system in embodiment 1 satisfies:

TTL/ImgH is 1.19; wherein, TTL is the on-axis distance from the object side surface of the first lens to the imaging surface, and ImgH is half of the diagonal length of the effective pixel area on the imaging surface.

f7/f × tan (Semi-FOV) ═ 1.05; where f1 is the effective focal length of the first lens, f7 is the effective focal length of the seventh lens, and the Semi-FOV is half the maximum field angle of the optical imaging system.

(CT1+ CT2+ CT3-T34)/BFL 0.95; wherein CT1 is a central thickness of the first lens element, CT2 is a central thickness of the second lens element, CT3 is a central thickness of the third lens element, T34 is an air gap between the third lens element and the fourth lens element, and BFL is a distance between an image-side surface of the last lens element and an image-side surface of the optical imaging system.

f7/R13+ f7/R14 is 17.66; wherein, R13 is the curvature radius of the object side surface of the seventh lens, and R14 is the curvature radius of the image side surface of the seventh lens.

L (R13+ R14)/(R13-R14) | 2.35; wherein, R13 is the curvature radius of the object side surface of the seventh lens, and R14 is the curvature radius of the image side surface of the seventh lens.

1.40, | f7/f8 |; wherein f7 is the effective focal length of the seventh lens, and f8 is the effective focal length of the eighth lens.

R3/R4 ═ 1.52; wherein R3 is the curvature radius of the object-side surface of the second lens, and R4 is the curvature radius of the image-side surface of the second lens.

1.81 | (f5+ f6)/f |; wherein f5 is the effective focal length of the fifth lens, f6 is the effective focal length of the sixth lens, and f is the effective focal length of the optical imaging system.

f 234/f-2.93; wherein f234 is the combined focal length of the second lens, the third lens and the fourth lens.

TTL/Σ AT is 2.53; wherein, TTL is the axial distance from the object side surface of the first lens to the imaging surface, and Σ AT is the sum of the air intervals on the optical axis between any two adjacent lenses with focal power in the first lens and the lens closest to the imaging surface.

3.03, | f4/f1 |; wherein f1 is the effective focal length of the first lens, and f4 is the effective focal length of the fourth lens.

SL/BFL ═ 7.76; wherein, SL is the distance from the diaphragm to the imaging surface on the axis, BFL is the distance from the last lens image side surface of the optical imaging system to the imaging surface on the optical axis.

f4567/f ═ 1.36; wherein f4567 is a combined focal length of the fourth lens, the fifth lens, the sixth lens and the seventh lens.

In example 1, the object-side surface and the image-side surface of any one of the first lens element E1 through the eighth lens element E8 are aspheric, and table 3 shows the high-order term coefficients a that can be used for the aspheric mirror surfaces S1 through S16 in example 1₄、A₆、A₈、A₁₀、A₁₂、A₁₄、A₁₆、A₁₈、A₂₀、A₂₂、A₂₄、A₂₆、A₂₈And A₃₀。

TABLE 3

Fig. 2a shows an on-axis chromatic aberration curve of the optical imaging system of embodiment 1, which represents the deviation of the convergent focal points of light rays of different wavelengths after passing through the lens. Fig. 2b shows an astigmatism curve of the optical imaging system of embodiment 1, which represents a meridional field curvature and a sagittal field curvature. As can be seen from fig. 2a to 2b, the optical imaging system according to embodiment 1 can achieve good imaging quality.

Specific example 2

Fig. 3 is a schematic view of a lens assembly structure of an optical imaging system in embodiment 2, the optical imaging system, in order from an object side to an image side along an optical axis, including: a stop STO, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, an eighth lens E8, a filter E9, and an image forming surface S19.

As shown in table 4, a basic parameter table of the optical imaging system of example 2 is shown, in which the units of the radius of curvature, the thickness, and the focal length are all millimeters (mm). The first lens E1 is preferably but not limited to GM material (mold glass), which has the characteristics of glass material, and is easy to manufacture aspheric lens, and is more advantageous for optimization.

TABLE 4

As shown in table 5, in embodiment 2, the total effective focal length f of the optical imaging system is 7.14mm, the distance TTL on the optical axis from the object side surface S1 of the first lens E1 to the imaging surface S19 of the optical imaging system is 9.00mm, and the half ImgH of the diagonal length of the effective pixel region on the imaging surface S19 is 7.40 mm. Half the maximum field angle Semi-FOV of the optical imaging system is 42.92 °. The aperture value Fno of the optical imaging system is 1.68.

TABLE 5

In example 2, the object-side surface and the image-side surface of any one of the first lens element E1 through the eighth lens element E8 are aspheric, and table 6 shows the high-order term coefficients a that can be used for the aspheric mirror surfaces S1 through S16 in example 2₄、A₆、A₈、A₁₀、A₁₂、A₁₄、A₁₆、A₁₈、A₂₀、A₂₂、A₂₄、A₂₆、A₂₈And A₃₀。

Flour mark

A4

A6

A8

A10

A12

A14

A16

S1

1.0610E-04

2.9349E-04

-3.3027E-04

2.1927E-04

-9.7344E-05

2.8261E-05

-5.3335E-06

S2

-7.3241E-03

3.5461E-03

-2.4165E-03

1.1571E-03

-3.3045E-04

5.2312E-05

-3.2204E-06

S3

-9.6543E-03

4.2420E-03

2.2134E-03

-9.9663E-03

1.4949E-02

-1.4277E-02

9.6807E-03

S4

-1.0451E-02

9.3839E-03

-1.8618E-02

4.0315E-02

-6.6276E-02

7.7556E-02

-6.4724E-02

S5

-1.2757E-02

2.7637E-03

-1.1028E-02

3.5411E-02

-7.3261E-02

9.7553E-02

-8.7619E-02

S6

-6.4024E-03

5.4501E-03

-2.1217E-02

4.4701E-02

-6.2081E-02

5.8353E-02

-3.7795E-02

S7

-2.2783E-02

-1.3423E-02

4.9517E-02

-1.0539E-01

1.4725E-01

-1.4493E-01

1.0343E-01

S8

-1.4143E-02

-2.9048E-02

6.7801E-02

-9.8817E-02

9.7416E-02

-6.8778E-02

3.5821E-02

S9

6.9210E-03

-3.0149E-02

5.0960E-02

-5.6469E-02

4.1504E-02

-2.0832E-02

7.3669E-03

S10

1.7064E-03

-1.0002E-02

7.6494E-03

-4.6130E-03

2.1311E-03

-7.1269E-04

1.6476E-04

S11

1.4768E-02

-1.8677E-02

1.5531E-02

-1.0169E-02

5.1175E-03

-1.9996E-03

6.0298E-04

S12

-2.0651E-02

-7.6965E-03

1.0540E-02

-5.9692E-03

2.2180E-03

-5.9895E-04

1.2148E-04

S13

-1.7956E-02

-2.4852E-04

1.0831E-03

-8.8034E-04

3.8187E-04

-1.0662E-04

2.0470E-05

S14

1.6686E-02

-3.7213E-03

-1.5289E-03

9.3393E-04

-2.5581E-04

4.5389E-05

-5.6728E-06

S15

-7.2708E-02

1.9297E-02

-4.1559E-03

6.6790E-04

-7.4031E-05

5.6561E-06

-3.0179E-07

S16

-7.9137E-02

2.3113E-02

-5.3430E-03

8.9631E-04

-1.0835E-04

9.4940E-06

-6.0682E-07

Flour mark

A18

A20

A22

A24

A26

A28

A30

S1

5.8848E-07

-2.9169E-08

0.0000E+00

S2

-1.7936E-07

2.4546E-08

0.0000E+00

S3

-4.8001E-03

1.7443E-03

-4.5823E-04

8.4474E-05

-1.0342E-05

7.5371E-07

-2.4712E-08

S4

3.8823E-02

-1.6748E-02

5.1434E-03

-1.0959E-03

1.5382E-04

-1.2779E-05

4.7574E-07

S5

5.4695E-02

-2.4031E-02

7.4086E-03

-1.5693E-03

2.1752E-04

-1.7767E-05

6.4833E-07

S6

1.6909E-02

-5.1227E-03

9.8987E-04

-1.0165E-04

6.8016E-07

9.5395E-07

-6.9574E-08

S7

-5.4166E-02

2.0814E-02

-5.7986E-03

1.1389E-03

-1.4944E-04

1.1747E-05

-4.1796E-07

S8

-1.3882E-02

3.9818E-03

-8.3138E-04

1.2251E-04

-1.2053E-05

7.0989E-07

-1.8918E-08

S9

-1.8736E-03

3.4521E-04

-4.5771E-05

4.2621E-06

-2.6473E-07

9.8570E-09

-1.6678E-10

S10

-2.3327E-05

9.1910E-07

3.5813E-07

-8.0870E-08

7.9216E-09

-3.8418E-10

7.2666E-12

S11

-1.3847E-04

2.3796E-05

-2.9892E-06

2.6503E-07

-1.5650E-08

5.5075E-10

-8.7184E-12

S12

-1.8676E-05

2.1686E-06

-1.8683E-07

1.1522E-08

-4.7804E-10

1.1886E-11

-1.3324E-13

S13

-2.7807E-06

2.6939E-07

-1.8452E-08

8.7067E-10

-2.6864E-11

4.8711E-13

-3.9312E-15

S14

5.1367E-07

-3.3869E-08

1.6090E-09

-5.3572E-11

1.1848E-12

-1.5613E-14

9.2692E-17

S15

1.1276E-08

-2.8999E-10

4.8666E-12

-4.5734E-14

9.0627E-17

2.3682E-18

-1.6764E-20

S16

2.8374E-08

-9.6756E-10

2.3763E-11

-4.0907E-13

4.6832E-15

-3.2021E-17

9.8956E-20

TABLE 6

Fig. 4a shows an on-axis chromatic aberration curve of the optical imaging system of embodiment 2, which represents the deviation of the convergent focal points of light rays of different wavelengths after passing through the lens. Fig. 4b shows an astigmatism curve of the optical imaging system of embodiment 2, which represents a meridional field curvature and a sagittal field curvature. As can be seen from fig. 4a to 4b, the optical imaging system according to embodiment 2 can achieve good imaging quality.

Specific example 3

Fig. 5 is a schematic view of a lens assembly structure of an optical imaging system in embodiment 3, the optical imaging system, in order from an object side to an image side along an optical axis, including: a stop STO, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, an eighth lens E8, a filter E9, and an image forming surface S19.

As shown in table 7, a basic parameter table of the optical imaging system of example 3 is shown, in which the units of the radius of curvature, the thickness, and the focal length are all millimeters (mm). The first lens E1 is preferably but not limited to GM material (mold glass), which has the characteristics of glass material, and is easy to manufacture aspheric lens, and is more advantageous for optimization.

TABLE 7

As shown in table 8, in embodiment 3, the total effective focal length f of the optical imaging system is 7.21mm, the distance TTL on the optical axis from the object side surface S1 of the first lens E1 to the imaging surface S19 of the optical imaging system is 9.25mm, and the half ImgH of the diagonal length of the effective pixel region on the imaging surface S19 is 7.40 mm. Half the maximum field angle of the optical imaging system Semi-FOV is 43.35 °. The aperture value Fno of the optical imaging system is 1.68.

TABLE 8

In example 3, the object-side surface and the image-side surface of any one of the first lens element E1 through the eighth lens element E8 are aspheric, and table 9 shows the high-order term coefficients a usable for the aspheric mirror surfaces S1 through S16 in example 3₄、A₆、A₈、A₁₀、A₁₂、A₁₄、A₁₆、A₁₈、A₂₀、A₂₂、A₂₄、A₂₆、A₂₈And A₃₀。

TABLE 9

Fig. 6a shows an on-axis chromatic aberration curve of the optical imaging system of embodiment 3, which represents the deviation of the convergent focal points of light rays of different wavelengths after passing through the lens. Fig. 6b shows an astigmatism curve of the optical imaging system of embodiment 3, which represents a meridional field curvature and a sagittal field curvature. As can be seen from fig. 6a to 6b, the optical imaging system according to embodiment 3 can achieve good imaging quality.

Specific example 4

Fig. 7 is a lens assembly structure of an optical imaging system in accordance with embodiment 4 of the present invention, the optical imaging system, in order from an object side to an image side along an optical axis, includes: a stop STO, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, an eighth lens E8, a filter E9, and an image forming surface S19.

As shown in table 10, the basic parameter table of the optical imaging system of example 4 is shown, in which the units of the radius of curvature, the thickness, and the focal length are all millimeters (mm). The first lens E1 is preferably but not limited to GM material (mold glass), which has the characteristics of glass material, and is easy to manufacture aspheric lens, and is more advantageous for optimization.

Watch 10

As shown in table 11, in embodiment 4, the total effective focal length f of the optical imaging system is 7.45mm, the distance TTL on the optical axis from the object side surface S1 of the first lens E1 to the imaging surface S19 of the optical imaging system is 9.25mm, and the half ImgH of the diagonal length of the effective pixel region on the imaging surface S19 is 7.40 mm. Half the maximum field angle Semi-FOV of the optical imaging system is 43.33 °. The aperture value Fno of the optical imaging system is 1.68.

TABLE 11

In example 4, the object-side surface and the image-side surface of any one of the first lens element E1 through the eighth lens element E8 are aspheric, and table 12 shows the high-order term coefficients a that can be used for the aspheric mirror surfaces S1 through S16 in example 4₄、A₆、A₈、A₁₀、A₁₂、A₁₄、A₁₆、A₁₈、A₂₀、A₂₂、A₂₄、A₂₆、A₂₈And A₃₀。

TABLE 12

Fig. 8a shows an on-axis chromatic aberration curve of the optical imaging system of embodiment 4, which represents the deviation of the convergent focal points of light rays of different wavelengths after passing through the lens. Fig. 8b shows an astigmatism curve representing meridional field curvature and sagittal field curvature of the optical imaging system of example 4. As can be seen from fig. 8a to 8b, the optical imaging system according to embodiment 4 can achieve good imaging quality.

Specific example 5

Fig. 9 is a lens assembly structure of the optical imaging system according to embodiment 5 of the present invention, the optical imaging system, in order from an object side to an image side along an optical axis, includes: a stop STO, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, an eighth lens E8, a filter E9, and an image forming surface S19.

As shown in table 13, the basic parameter table of the optical imaging system of example 5 is shown, in which the units of the radius of curvature, the thickness, and the focal length are all millimeters (mm). The first lens E1 is preferably but not limited to GM material (mold glass), which has the characteristics of glass material, and is easy to manufacture aspheric lens, and is more advantageous for optimization.

Watch 13

As shown in table 14, in embodiment 5, the total effective focal length f of the optical imaging system is 7.82mm, the distance TTL on the optical axis from the object side surface S1 of the first lens E1 to the imaging surface S19 of the optical imaging system is 9.75mm, and the half ImgH of the diagonal length of the effective pixel region on the imaging surface S19 is 7.40 mm. Half the maximum field angle Semi-FOV of the optical imaging system is 42.57 °. The aperture value Fno of the optical imaging system is 1.68.

TABLE 14

In example 5, the object-side surface and the image-side surface of any one of the first lens element E1 to the eighth lens element E8 are aspheric, and table 15 shows the high-order term coefficients a that can be used for the aspheric mirror surfaces S1 to S16 in example 5₄、A₆、A₈、A₁₀、A₁₂、A₁₄、A₁₆、A₁₈、A₂₀、A₂₂、A₂₄、A₂₆、A₂₈And A₃₀。

Flour mark

A4

A6

A8

A10

A12

A14

A16

S1

4.8527E-04

5.1334E-05

-1.7533E-04

2.1935E-04

-1.4128E-04

5.0868E-05

-1.0601E-05

S2

-7.7527E-03

4.5100E-03

-3.8126E-03

2.3357E-03

-9.2338E-04

2.3498E-04

-3.7076E-05

S3

-1.0262E-02

8.2305E-03

-1.0267E-02

1.2751E-02

-1.2696E-02

9.6427E-03

-5.4651E-03

S4

-8.7036E-03

5.6798E-03

-1.0717E-02

2.7833E-02

-5.3245E-02

6.8427E-02

-6.0117E-02

S5

-1.1716E-02

4.6286E-03

-1.6712E-02

3.9965E-02

-6.6318E-02

7.5863E-02

-6.1021E-02

S6

-5.6558E-03

8.2229E-04

-3.6226E-03

4.3295E-03

-2.5523E-03

-6.3414E-04

2.5494E-03

S7

-2.3666E-02

-7.2262E-03

3.1329E-02

-7.8091E-02

1.2621E-01

-1.4149E-01

1.1279E-01

S8

-1.4697E-02

-2.4763E-02

5.7755E-02

-8.5958E-02

8.7060E-02

-6.3185E-02

3.3782E-02

S9

4.9658E-03

-2.3816E-02

4.3219E-02

-5.1504E-02

4.0848E-02

-2.2311E-02

8.6810E-03

S10

-1.2800E-03

-7.7289E-03

1.0398E-02

-1.1499E-02

9.3390E-03

-5.4480E-03

2.2993E-03

S11

6.3992E-03

-6.8108E-03

4.0743E-03

-1.9483E-03

6.2102E-04

-1.3097E-04

1.8768E-05

S12

-1.7454E-02

-5.5956E-03

8.2656E-03

-4.8864E-03

1.8752E-03

-5.1767E-04

1.0617E-04

S13

-1.2973E-02

-5.6738E-03

4.2898E-03

-2.0411E-03

6.6979E-04

-1.5782E-04

2.7041E-05

S14

1.4843E-02

-8.3056E-03

1.6187E-03

-1.5695E-04

-9.4316E-06

5.9725E-06

-1.0503E-06

S15

-3.9074E-02

4.8594E-03

-4.2821E-04

4.3620E-05

-2.6738E-06

-1.0451E-07

3.3702E-08

S16

-4.0895E-02

7.7578E-03

-1.4664E-03

2.3161E-04

-2.7669E-05

2.4347E-06

-1.5741E-07

Flour mark

A18

A20

A22

A24

A26

A28

A30

S1

1.1888E-06

-5.6353E-08

0.0000E+00

S2

3.2812E-06

-1.2505E-07

0.0000E+00

S3

2.3002E-03

-7.1638E-04

1.6323E-04

-2.6492E-05

2.9027E-06

-1.9240E-07

5.8203E-09

S4

3.6874E-02

-1.5941E-02

4.8351E-03

-1.0067E-03

1.3698E-04

-1.0965E-05

3.9142E-07

S5

3.5013E-02

-1.4380E-02

4.1906E-03

-8.4512E-04

1.1204E-04

-8.7765E-06

3.0756E-07

S6

-2.3489E-03

1.2658E-03

-4.4903E-04

1.0668E-04

-1.6423E-05

1.4849E-06

-5.9943E-08

S7

-6.4664E-02

2.6693E-02

-7.8540E-03

1.6054E-03

-2.1646E-04

1.7299E-05

-6.2032E-07

S8

-1.3410E-02

3.9308E-03

-8.3660E-04

1.2532E-04

-1.2499E-05

7.4373E-07

-1.9954E-08

S9

-2.4589E-03

5.1119E-04

-7.7529E-05

8.3784E-06

-6.1310E-07

2.7294E-08

-5.5915E-10

S10

-7.0611E-04

1.5751E-04

-2.5219E-05

2.8217E-06

-2.0937E-07

9.2536E-09

-1.8435E-10

S11

-2.3404E-06

4.2121E-07

-8.3822E-08

1.1550E-08

-9.6018E-10

4.3790E-11

-8.4532E-13

S12

-1.6298E-05

1.8621E-06

-1.5556E-07

9.1898E-09

-3.6209E-10

8.5081E-12

-8.9947E-14

S13

-3.3805E-06

3.0695E-07

-1.9947E-08

9.0071E-10

-2.6768E-11

4.6980E-13

-3.6843E-15

S14

1.1165E-07

-8.0107E-09

3.9702E-10

-1.3417E-11

2.9511E-13

-3.8037E-15

2.1758E-17

S15

-2.9614E-09

1.4996E-10

-4.9075E-12

1.0595E-13

-1.4649E-15

1.1800E-17

-4.2220E-20

S16

7.4840E-09

-2.6069E-10

6.5685E-12

-1.1651E-13

1.3802E-15

-9.8081E-18

3.1642E-20

Watch 15

Fig. 10a shows an on-axis chromatic aberration curve of the optical imaging system of embodiment 5, which represents the deviation of the convergent focal points of light rays of different wavelengths after passing through the lens. Fig. 10b shows an astigmatism curve representing meridional field curvature and sagittal field curvature of the optical imaging system of example 5. As can be seen from fig. 10a to 10b, the optical imaging system according to embodiment 5 can achieve good imaging quality.

Specific example 6

Fig. 11 is a lens assembly structure of an optical imaging system according to embodiment 6 of the present invention, the optical imaging system, in order from an object side to an image side along an optical axis, comprising: a stop STO, a first lens E1, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a seventh lens E7, an eighth lens E8, a filter E9, and an image forming surface S19.

As shown in table 16, the basic parameter table of the optical imaging system of example 6 is shown, in which the units of the radius of curvature, the thickness, and the focal length are all millimeters (mm). The first lens E1 is preferably but not limited to GM material (mold glass), which has the characteristics of glass material, and is easy to manufacture aspheric lens, and is more advantageous for optimization.

TABLE 16

As shown in table 17, in embodiment 6, the total effective focal length f of the optical imaging system is 7.93mm, the distance TTL on the optical axis from the object side surface S1 of the first lens E1 to the imaging surface S19 of the optical imaging system is 9.93mm, and the half ImgH of the diagonal length of the effective pixel region on the imaging surface S19 is 7.40 mm. Half the maximum field angle Semi-FOV of the optical imaging system is 41.67 °. The aperture value Fno of the optical imaging system is 1.68.

TABLE 17

In example 6, the object-side surface and the image-side surface of any one of the first lens element E1 to the eighth lens element E8 are aspheric, and table 18 shows that these lenses can be used in example 6High-order coefficient A of each aspherical mirror surface S1-S16₄、A₆、A₈、A₁₀、A₁₂、A₁₄、A₁₆、A₁₈、A₂₀、A₂₂、A₂₄、A₂₆、A₂₈And A₃₀。

Watch 18

Fig. 12a shows an on-axis chromatic aberration curve of the optical imaging system of embodiment 6, which represents the deviation of the convergent focal points of light rays of different wavelengths after passing through the lens. Fig. 12b shows an astigmatism curve representing meridional field curvature and sagittal field curvature of the optical imaging system of example 6. As can be seen from fig. 12a to 12b, the optical imaging system according to embodiment 6 can achieve good imaging quality.

The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, improvements, equivalents and the like that fall within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims

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

a first lens;

a second lens having a negative optical power;

a third lens;

a fourth lens element having a concave image-side surface;

a fifth lens;

a sixth lens having a negative optical power;

an eighth lens;

2. The optical imaging system of claim 1, wherein the effective focal length f1 of the first lens, the effective focal length f7 of the seventh lens, and half the Semi-FOV of the maximum field angle of the optical imaging system satisfy: 1.0 ≦ f7/f × tan (Semi-FOV) ≦ 1.2.

3. The optical imaging system of claim 1, wherein the central thickness CT1 of the first lens on the optical axis, the central thickness CT2 of the second lens on the optical axis, the central thickness CT3 of the third lens on the optical axis, the air space T34 of the third lens and the fourth lens on the optical axis, and the distance BFL from the image side surface of the last lens of the optical imaging system to the image plane on the optical axis satisfy: 0.5 ≦ (CT1+ CT2+ CT3-T34)/BFL ≦ 1.2.

4. The optical imaging system of claim 1, wherein the radius of curvature R13 of the object-side surface of the seventh lens and the radius of curvature R14 of the image-side surface of the seventh lens satisfy: 16 ≦ f7/R13+ f7/R14 ≦ 20.

5. The optical imaging system of claim 1, wherein the radius of curvature R13 of the object-side surface of the seventh lens and the radius of curvature R14 of the image-side surface of the seventh lens satisfy: 1.5 ≦ (R13+ R14)/(R13-R14) | ≦ 3.5.

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

a first lens;

a second lens having a negative optical power;

a third lens;

a fourth lens;

a sixth lens having a negative optical power;

a seventh lens;

7. The optical imaging system according to claim 6, wherein a sum Σ AT of an on-axis distance TTL from an object side surface of the first lens to the imaging plane and an air interval on the optical axis between the first lens and any adjacent two of the lenses having optical powers in the lens closest to the imaging plane satisfies: 2.5 ≦ TTL/Σ AT ≦ 3.0.

8. The optical imaging system of claim 6, wherein the effective focal length f1 of the first lens and the effective focal length f4 of the fourth lens satisfy: 2.0 ≦ f4/f1| ≦ 3.5.

9. The optical imaging system of claim 6, wherein an on-axis distance SL from the stop to the imaging surface and an on-axis distance BFL from the image-side surface of the last lens of the optical imaging system to the imaging surface satisfy: 6.5 ≦ SL/BFL ≦ 8.5.

10. The optical imaging system of claim 6, wherein the combined focal length f4567 of the fourth lens, the fifth lens, the sixth lens and the seventh lens satisfies: 1.0 ≦ f4567/f ≦ 1.5.