Imaging system

Abstract

The application discloses an imaging system, including a lens group, a plurality of spacer elements and a lens barrel, the lens group sequentially includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens from the object side to the image side along the optical axis, wherein the number of lenses with optical power in the lens group is six. The plurality of spacer elements includes a third spacer element and a fourth spacer element. The imaging system satisfies: 5.0<(D4s-CP4)N4 / CT4<12.5 and 4.5<R8 / f+d4s / EP34<8.5, wherein D4s is the outer diameter of the object side surface of the fourth spacer element, CP4 is the maximum thickness of the fourth spacer element, N4 is the refractive index of the fourth lens, CT4 is the center thickness of the fourth lens, R8 is the curvature radius of the image side surface of the fourth lens, f is the total effective focal length of the imaging system, d4s is the inner diameter of the object side surface of the fourth spacer element, and EP34 is the distance between the third spacer element and the fourth spacer element.

Description

[0001] Divisional Application Declaration

[0002] This application is a divisional application of the China Invention Patent Application No. 202210836226.X, filed on July 15, 2022, entitled “Imaging System” and claiming priority to the China Invention Patent Application No. 202210836226.X, filed on July 15, 2022, entitled “Imaging System”. TECHNICAL FIELD

[0003] The present application relates to the field of optical elements, in particular, to an imaging system. BACKGROUND

[0004] With the gradual maturity of AR / VR technology, the market of smart glasses such as AR glasses and VR glasses gradually rises, thereby putting forward the requirements of miniaturization and high imaging performance for the imaging lens and its matching components (for example, lens barrel) carried by the smart glasses.

[0005] Wide-angle lenses are widely used in AR or VR application scenarios such as environmental perception, spatial positioning, gesture control, etc. due to their wider shooting angle. However, the size of the wide-angle lenses on the market is usually large. In addition, the imaging lens usually includes multiple lenses and spacer elements for coupling adjacent lenses, and the large gap between the lenses causes the problem of assembly stability. Moreover, with the increase of the image plane, the edge of the lens is prone to stray light phenomenon. The above stray light and assembly stability problems seriously affect the imaging quality of the imaging lens.

[0006] Therefore, how to reasonably set the optical parameters of the imaging lens and the lens barrel and the structure and size relationship of the lenses and the spacer elements, so as to improve the stray light problem and ensure the assembly stability of the imaging lens under the premise of realizing wide angle and miniaturization is a problem to be solved in the field.

[0007] It should be understood that this Background section is intended to provide useful background for understanding the technology, however, the content of this section does not necessarily constitute the content known or understood by those skilled in the art prior to the filing date of this application. SUMMARY

[0008] The application provides an imaging system, comprising a lens set, a plurality of spacer elements, and a lens barrel for accommodating the lens set and the plurality of spacer elements, the lens set sequentially comprises, along an optical axis from an object side to an image side, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens, wherein the number of lenses with optical power in the lens set is six, the first lens has negative optical power, the second lens has positive optical power, and the third lens has negative optical power; the plurality of spacer elements comprises a first spacer element in contact with an image side surface portion of the first lens, a second spacer element in contact with an image side surface portion of the second lens, a third spacer element in contact with an image side surface portion of the third lens, a fourth spacer element in contact with an image side surface portion of the fourth lens, and a fifth spacer element in contact with an image side surface portion of the fifth lens; wherein the size of the lens barrel along the optical axis direction is less than 5.0 mm, and the imaging system satisfies: 634.0 < (L + TD) < 700.0, tan(Semi-FOV) / CPmin < 722.5; wherein L is the size of the lens barrel along the optical axis direction, TD is the distance from the object side surface of the first lens to the image side surface of the sixth lens along the optical axis, Semi-FOV is the maximum semi-field of view of the imaging system, and CPmin is the minimum value of the maximum thickness of each of the first spacer element to the fifth spacer element.

[0009] In an embodiment of the application, the imaging system satisfies: R3 / R4 < 0, wherein R3 is the radius of curvature of the object side surface of the second lens, and R4 is the radius of curvature of the image side surface of the second lens. In an embodiment of the application, the imaging system satisfies: f4 / f5 < 0, and R8 / R11 < 0; wherein f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, R8 is the radius of curvature of the image side surface of the fourth lens, and R11 is the radius of curvature of the object side surface of the sixth lens.

[0010] In an embodiment of the application, the material of the fourth lens is glass.

[0011] In an embodiment of the application, the outer diameter of the object side surface of any one of at least two spacer elements included in the first spacer element to the fifth spacer element is equal to the outer diameter of the image side surface of the any one, and the inner diameter of the object side surface of the any one is equal to the inner diameter of the image side surface of the any one.

[0012] ​In one embodiment of the present application, the imaging system satisfies: -24.5 < (f3 + f2) / (EP23 - CP2) < -3.0, where f3 is the effective focal length of the third lens, f2 is the effective focal length of the second lens, EP23 is the distance along the optical axis of the image side surface of the second spacer element and the object side surface of the third spacer element, and CP2 is the maximum thickness of the second spacer element.

[0013] In one embodiment of the present application, the imaging system satisfies: 5.0 < (D4s - CP4) / N4 / CT4 < 12.5, where D4s is the outer diameter of the object side surface of the fourth spacer element, CP4 is the maximum thickness of the fourth spacer element, N4 is the refractive index of the fourth lens, and CT4 is the center thickness of the fourth lens.

[0014] In one embodiment of the present application, the imaging system satisfies: 0 < (D1m - d1m) / R2 / (CP1 / T12) < 20.5, where D1m is the outer diameter of the image side surface of the first spacer element, d1m is the inner diameter of the image side surface of the first spacer element, R2 is the curvature radius of the image side surface of the first lens, CP1 is the maximum thickness of the first spacer element, and T12 is the air gap of the first lens and the second lens on the optical axis.

[0015] In one embodiment of the present application, the imaging system satisfies: 4.0 < (R2 + R3) / (CT2 - EP12 + CP1) < 27.5, where R2 is the curvature radius of the image side surface of the first lens, R3 is the curvature radius of the object side surface of the second lens, CT2 is the center thickness of the second lens, EP12 is the distance of the first spacer element and the second spacer element, and CP1 is the maximum thickness of the first spacer element.

[0016] In one embodiment of the present application, the imaging system satisfies: 3.5 < (D2s - d2s + D2m) / (T23 + CT2) < 9.5, where D2s is the outer diameter of the object side surface of the second spacer element, d2s is the inner diameter of the object side surface of the second spacer element, D2m is the outer diameter of the image side surface of the second spacer element, T23 is the air gap of the second lens and the third lens on the optical axis, and CT2 is the center thickness of the second lens.

[0017] In one embodiment of the present application, the imaging system satisfies: -13.0 < (D3m - d3s) / (T34 - CT3) < 5.0, where D3m is the outer diameter of the image side surface of the third spacer element, d3s is the inner diameter of the image side surface of the third spacer element, T34 is the air gap of the third lens and the fourth lens on the optical axis, and CT3 is the center thickness of the third lens. ​​R7 < 7.5, where D3m is an outer diameter of an image-side surface of the third spacer element, d3s is an inner diameter of an object-side surface of the third spacer element, T34 is an air gap of the third lens and the fourth lens on the optical axis, and R7 is a curvature radius of the object-side surface of the fourth lens.

[0018] In one embodiment of the present application, the imaging system satisfies 4.5 < R8 / f+d4s / EP34 < 8.5, where R8 is a curvature radius of an image-side surface of the fourth lens, f is a total effective focal length of the imaging system, d4s is an inner diameter of an object-side surface of the fourth spacer element, and EP34 is a distance between the third spacer element and the fourth spacer element.

[0019] In one embodiment of the present application, the imaging system satisfies 0 < (D4s+d4s) / (R7-R8) < 19.5, where D4s is an outer diameter of an object-side surface of the fourth spacer element, d4s is an inner diameter of the object-side surface of the fourth spacer element, R7 is a curvature radius of the object-side surface of the fourth lens, and R8 is a curvature radius of the image-side surface of the fourth lens.

[0020] In one embodiment of the present application, the imaging system satisfies 53.0 < D5m / T56+d4m / T45 < 74.0, where D5m is an outer diameter of an image-side surface of the fifth spacer element, T56 is an air gap of the fifth lens and the sixth lens on the optical axis, d4m is an inner diameter of an image-side surface of the fourth spacer element, and T45 is an air gap of the fourth lens and the fifth lens on the optical axis.

[0021] In one embodiment of the present application, the imaging system satisfies 6.5 < (L-EP15) / (T23+CT3+T34) FNO < 9.5, where L is a size of the lens barrel in the direction of the optical axis, EP15 is a distance of the first spacer element to the fifth spacer element in the direction of the optical axis, T23 is an air gap of the second lens and the third lens on the optical axis, CT3 is a center thickness of the third lens, T34 is an air gap of the third lens and the fourth lens on the optical axis, and FNO is an F number of the imaging system.

[0022] In one embodiment of the present application, the imaging system satisfies -11.5 < (D5s+D1s) / (R11-R2) < -6.0,

[0023] where D5s is an outer diameter of an object-side surface of the fifth spacer element, D1s is an outer diameter of an object-side surface of the first spacer element, R11 is a curvature radius of an object-side surface of the sixth lens, and R2 is a curvature radius of an image-side surface of the first lens.

[0024] In an embodiment of the present application, the imaging system satisfies: -8.0 < (CT3-CT2) / (EP23-EP12) < 12.0,

[0025] wherein CT3 is the center thickness of the third lens, CT2 is the center thickness of the second lens, EP23 is the distance between the image side surface of the second spacer element and the object side surface of the third spacer element along the optical axis, and EP12 is the distance between the first spacer element and the second spacer element.

[0026] In an embodiment of the present application, the imaging system satisfies: 7.5 < |(R9+R10) / (CP5+CP4)| < 93.5, wherein R9 is the radius of curvature of the object side surface of the fifth lens, R10 is the radius of curvature of the image side surface of the fifth lens, CP5 is the maximum thickness of the fifth spacer element, and CP4 is the maximum thickness of the fourth spacer element.

[0027] In an embodiment of the present application, the imaging system satisfies: 0 < (R3+R4) / (D2s-D1s) < 16.5, wherein R3 is the radius of curvature of the object side surface of the second lens, R4 is the radius of curvature of the image side surface of the second lens, D2s is the outer diameter of the object side surface of the second spacer element, and D1s is the outer diameter of the object side surface of the first spacer element.

[0028] Another aspect of the present application provides an imaging system, comprising a lens group, a plurality of spacer elements, and a lens barrel for accommodating the lens group and the plurality of spacer elements. The lens group comprises, in order from an object side to an image side along an optical axis, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens, wherein the number of lenses having optical power in the lens group is six. The plurality of spacer elements comprises a third spacer element in partial contact with an image side surface of the third lens, and a fourth spacer element in partial contact with an image side surface of the fourth lens. The imaging system satisfies: 5.0 < (D4s-CP4) N4 / CT4 < 12.5 and 4.5 < R8 / f+d4s / EP34 < 8.5, wherein D4s is the outer diameter of the object side surface of the fourth spacer element, CP4 is the maximum thickness of the fourth spacer element, N4 is the refractive index of the fourth lens, CT4 is the center thickness of the fourth lens, R8 is the radius of curvature of the image side surface of the fourth lens, f is the total effective focal length of the imaging system, d4s is the inner diameter of the object side surface of the fourth spacer element, and EP34 is the distance between the third spacer element and the fourth spacer element.

[0029] The imaging system of the present application comprises a lens group, a plurality of spacer elements, and a lens barrel for accommodating the lens group and the plurality of spacer elements, the relative illumination and distortion and other performance indicators of the imaging system are controlled within a reasonable range by controlling the optical power of the first lens, the second lens and the third lens; at the same time, by reasonably arranging the spacer elements between the lenses, the assembly stability of the imaging system can be improved. Further, by reasonably controlling the relationship between the minimum value of the difference between the size of the lens barrel along the optical axis and the distance along the optical axis from the object side of the first lens to the image side of the sixth lens, the field of view angle of the imaging system and the thickness of each of the plurality of spacer elements, the imaging system can have a large field of view angle while constraining the axial length of the lens group, and by further constraining the size of the lens barrel in the optical axis direction, the miniaturization of the imaging system is realized. BRIEF DESCRIPTION OF DRAWINGS

[0030] Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments made with reference to the accompanying drawings:

[0031] Figure 1 A parameter labeling diagram of an imaging system according to the present application is shown;

[0032] Figure 2 A cross-sectional schematic diagram of an imaging system according to Embodiment 1 of the present application is shown;

[0033] Figure 3 A cross-sectional schematic diagram of another imaging system according to Embodiment 1 of the present application is shown;

[0034] Figure 4 A cross-sectional schematic diagram of still another imaging system according to Embodiment 1 of the present application is shown;

[0035] Figures 5A to 5C Axial chromatic aberration curves, magnification chromatic aberration curves and astigmatism curves of the imaging system according to Embodiment 1 of the present application are shown respectively;

[0036] Figure 6 A cross-sectional schematic diagram of an imaging system according to Embodiment 2 of the present application is shown;

[0037] Figure 7 A cross-sectional schematic diagram of another imaging system according to Embodiment 2 of the present application is shown;

[0038] Figure 8 A cross-sectional schematic diagram of still another imaging system according to Embodiment 2 of the present application is shown;

[0039] Figures 9A to 9C Axial chromatic aberration curves, magnification chromatic aberration curves and astigmatism curves of the imaging system according to Embodiment 2 of the present application are shown respectively;

[0040] Figure 10 FIG. 3 shows a cross-sectional schematic view of an imaging system according to an embodiment of the present application;

[0041] Figure 11 FIG. 4 shows a cross-sectional schematic view of another imaging system according to an embodiment of the present application;

[0042] Figure 12 FIG. 5 shows a cross-sectional schematic view of still another imaging system according to an embodiment of the present application; and

[0043] Figures 13A to 13C FIGS. 6A, 6B and 6C respectively show an on-axis chromatic aberration curve, a magnification chromatic aberration curve and a distortion curve of the imaging system according to an embodiment of the present application. DETAILED DESCRIPTION

[0044] For a better understanding of the present application, various aspects of the present application will be described in greater detail below with reference to the accompanying drawings. It is to be understood that the detailed description is merely exemplary of the application and is not intended to limit the scope of the application in any way. Throughout the specification, like reference numerals refer to like elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0045] In the drawings, the thickness, size, and shape of lenses have been exaggerated slightly for ease of explanation. Specifically, the shape of a spherical surface or an aspherical surface shown in the drawings is shown by way of example. That is, the shape of a spherical surface or an aspherical surface is not limited to the shape of a spherical surface or an aspherical surface shown in the drawings. The drawings are merely examples and are not drawn to scale.

[0046] In this document, the paraxial region refers to a region near the optical axis. If a lens surface is convex and the position of the convex surface is not specified, it means that the lens surface is convex at least in the paraxial region. If a lens surface is concave and the position of the concave surface is not specified, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is referred to as the object side surface of the lens, and the surface of each lens closest to the imaging plane is referred to as the image side surface of the lens.

[0047] It should be noted that the expressions first, second, third, etc. in the present specification are merely used to distinguish one feature from another feature, and do not represent any limitation on the features. Thus, the first lens discussed below can also be referred to as the second lens or the third lens without departing from the teachings of the present application.

[0048] It should also be understood that the use of the terms "including", "including having", "having", "containing", and / or "containing having" when used in this specification, specifies 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. In addition, when terms such as "at least one of" appear in a list of items, they are used to modify the entire list of items, and do not modify the items individually. In addition, when describing embodiments of the present application, the use of "may" means "one or more embodiments of the present application". Also, the term "exemplary" is intended to refer to an example or illustration.

[0049] 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 should also be understood that the terms 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.

[0050] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict. The following embodiments only express several embodiments of the present application, which are described in detail and specifically, but can not be understood as limitations to the scope of the patent of the present application. It should be noted that, for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are within the scope of protection of the present application, for example, the lens group, the lens barrel and the spacer element in each embodiment of the present application can be combined arbitrarily, and are not limited to the combination of the lens group, the lens barrel, the spacer element and the like in the embodiment. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0051] The features, principles and other aspects of the present application are described in detail below.

[0052] The imaging system according to the exemplary embodiments of the present application can include a lens group, a plurality of spacer elements, and a lens barrel for accommodating the lens group and the plurality of spacer elements, wherein the lens group includes, in order from an object side to an image side along an optical axis, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens.

[0053] In exemplary embodiments, the first lens can have a negative focal power, the object side surface thereof can be convex or concave, the image side surface thereof can be convex or concave, the second lens can have a positive focal power, the object side surface thereof can be convex, and the image side surface thereof can be convex; the third lens can have a negative focal power, the object side surface thereof can be concave, and the image side surface thereof can be convex or concave; the fourth lens can have a positive focal power or a negative focal power, the object side surface thereof can be convex or concave, and the image side surface thereof can be convex; the fifth lens can have a positive focal power or a negative focal power, the object side surface thereof can be concave or convex, and the image side surface thereof can be convex or concave; and the sixth lens can have a positive focal power or a negative focal power, the object side surface thereof can be convex, and the image side surface thereof can be concave. By reasonably allocating the surface shape and focal power of each lens of the imaging system, the imaging effect can be effectively improved. In addition, by reasonably controlling the surface shape of each lens, the path of light in the optical system can be adjusted, the resolution of the imaging system can be effectively improved, and the aberration of the imaging system can be balanced.

[0054] In exemplary embodiments, the plurality of spacer elements includes at least one spacer element located between any two adjacent lenses, and the at least one spacer element is in contact with at least a portion of the adjacent lens. Specifically, the plurality of spacer elements includes, for example, a first spacer element located between the first lens and the second lens, a second spacer element located between the second lens and the third lens, a third spacer element located between the third lens and the fourth lens, a fourth spacer element located between the fourth lens and the fifth lens, and a fifth spacer element located between the fifth lens and the sixth lens. Optionally, the first spacer element can be in contact with a portion of the image side surface of the first lens, the second spacer element can be in contact with a portion of the image side surface of the second lens, the third spacer element can be in contact with a portion of the image side surface of the third lens, the fourth spacer element can be in contact with a portion of the image side surface of the fourth lens, and the fifth spacer element can be in contact with a portion of the image side surface of the fifth lens. Optionally, the portion of the image side surface of any one of the above-mentioned first to fifth spacer elements in contact with the adjacent lens can include a non-effective optical portion (for example, an edge region of the lens). By providing a plurality of spacer elements and making each spacer element in contact with the adjacent lens, it is helpful to intercept the excess reflected light path, improve the imaging cleanliness of the imaging system, reduce the generation of stray light and ghost, and ensure that the plurality of spacer elements are sequentially assembled with the lens barrel and the lens and ensure the stability after assembly.

[0055] In exemplary embodiments, the outer diameter of the object side surface of any one of the at least two spacer elements included in the first to fifth spacer elements is equal to the outer diameter of the image side surface, and the inner diameter of the object side surface of any one of the at least two spacer elements is equal to the inner diameter of the image side surface. The at least two spacer elements provided as above can have a relatively thin thickness, thereby effectively blocking the excess light and reducing the stray light.

[0056] In exemplary embodiments, with reference toFigure 1 The dimensions of the imaging system are specified such that the dimension of the lens barrel P0 along the optical axis is less than 5.0 mm. By constraining the dimension of the lens barrel P0, it is beneficial to achieve miniaturization of the imaging system.

[0057] In an exemplary implementation, reference Figure 1 The dimensions of the imaging system must satisfy: 634.0 < (L + TD) tan(Semi-FOV) / CPmin < 722.5; where L is the dimension of the lens barrel along the optical axis, TD is the distance along the optical axis from the object-side surface of the first lens to the image-side surface of the sixth lens, Semi-FOV is the maximum half-field of view of the imaging system, and CPmin is the minimum of the maximum thicknesses of the spacers from the first to the fifth spacers. Furthermore, the imaging system satisfies: 634.5 < (L + TD) tan(Semi-FOV) / CPmin < 722.0. Furthermore, by rationally controlling the relationship between the dimension of the lens barrel along the optical axis, the difference in distance along the optical axis between the object-side surface of the first lens and the image-side surface of the sixth lens, the field of view of the imaging system, and the minimum value among the thicknesses of the multiple spacer elements, it is possible to enable the imaging system to have a large field of view while constraining the axial length of the lens group. By further constraining the dimension of the lens barrel along the optical axis, miniaturization of the imaging system is achieved.

[0058] Understandably, this was done to make the structure and labels of the attached figures clearer. Figure 1 The marking of the dimensions of each component has been simplified. Only a set of dimensions of the first spacer element, the distance between the first spacer element and the third spacer element along the optical axis, and the maximum thickness of the third spacer element are marked as examples. For the relevant dimension limitations of the other spacer elements, please refer to the exemplary markings. This application will not elaborate on them here.

[0059] In an exemplary implementation, reference Figure 1 The dimensions of the imaging system satisfy the following condition: -24.5 < (f3 + f2) / (EP23 - CP2) < -3.0, where f3 is the effective focal length of the third lens, f2 is the effective focal length of the second lens, EP23 is the distance along the optical axis between the image side of the second spacer element and the object side of the third spacer element, and CP2 is the maximum thickness of the second spacer element. By reasonably controlling the ratio of the sum of the effective focal lengths of the second and third lenses, and the ratio of the distance along the optical axis between the second and third spacers element to the maximum thickness of the second spacer element, the imaging system can be constrained in terms of both relative illumination in the outer field of view and the length of the middle section of the imaging system.

[0060] In the example embodiments, the imaging system satisfies: R3 / R4<0, where R3 is the radius of curvature of the object side surface of the second lens, and R4 is the radius of curvature of the image side surface of the second lens. Further, the imaging system satisfies: -2.5<R3 / R4<0. By reasonably controlling the range of the radius of curvature of the object side surface and the image side surface of the second lens, i.e., reasonably controlling the bending direction and the bending size of the object side surface and the image side surface of the second lens, the second lens can have a good ability to balance the axial chromatic aberration, so that the optical imaging system obtains good imaging quality within a certain imaging wavelength bandwidth range. In the example embodiments, the imaging system satisfies: f4 / f5<0 and R8 / R11<0, where f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, R8 is the radius of curvature of the image side surface of the fourth lens, and R11 is the radius of curvature of the object side surface of the sixth lens. Further, the imaging system satisfies: -4.0<f4 / f5<0 and -4.5<R8 / R11<0. By reasonably controlling the ratio of the radius of curvature of the image side surface of the fourth lens and the radius of curvature of the object side surface of the sixth lens within a reasonable range, the ability of the imaging system to correct aberration of the edge field of view is improved, the imaging surface height of the system is increased, the imaging range of the system is wider, and the processing workability of the fourth lens and the sixth lens is improved. In addition, by reasonably limiting the ratio of the optical power of the fourth lens and the fifth lens, the fourth lens can have a good ability to balance the astigmatism of the imaging system.

[0061] In the example embodiments, the imaging system satisfies: 5.0<(D4s-CP4) N4 / CT4<12.5, where D4s is the outer diameter of the object side surface of the fourth spacer element, CP4 is the maximum thickness of the fourth spacer element, N4 is the refractive index of the fourth lens, and CT4 is the central thickness of the fourth lens. Further, the imaging system satisfies: 5.5<(D4s-CP4) N4 / CT4<12.0. By reasonably controlling the relationship among the outer diameter of the object side surface of the fourth spacer element and the difference between the thickness, the central thickness of the fourth lens, and the refractive index of the fourth lens, the stray light reflected by the internal optical structure of the fourth lens can be effectively absorbed, the interference influence of the assembly bearing surface is reduced, the lens bearing density is improved, and the structural stability and imaging quality of the imaging system are improved.

[0062] In an exemplary embodiment, the imaging system satisfies: 0 < (D1m-d1m) / R2 / (CP1 / T12) < 20.5, where D1m is the outer diameter of the image side surface of the first spacer element, d1m is the inner diameter of the image side surface of the first spacer element, R2 is the radius of curvature of the image side surface of the first lens, CP1 is the maximum thickness of the first spacer element, and T12 is the air gap of the first lens and the second lens on the optical axis. Further, the imaging system satisfies: 0.5 < (D1m-d1m) / R2 / (CP1 / T12) < 20.0. By constraining the relationship between the difference between the outer diameter and the inner diameter of the image side surface of the first spacer element, the radius of curvature of the image side surface of the first lens, the maximum thickness of the first spacer element, and the air gap of the first lens and the second lens on the optical axis, the profile shape of the first spacer element can be reasonably set, and the stray light is reduced while ensuring the processability and the reliability of the assembly support of the imaging system.

[0063] In an exemplary embodiment, the imaging system satisfies: 4.0 < (R2+R3) / (CT2-EP12+CP1) < 27.5, where R2 is the radius of curvature of the image side surface of the first lens, R3 is the radius of curvature of the object side surface of the second lens, CT2 is the center thickness of the second lens, EP12 is the distance of the first spacer element and the second spacer element, and CP1 is the maximum thickness of the first spacer element. Further, the imaging system satisfies: 4.5 < (R2+R3) / (CT2-EP12+CP1) < 27.0. By reasonably controlling the ratio relationship between the sum of the radius of curvature of the image side surface of the first lens and the object side surface of the second lens, the difference between the center thickness of the second lens and the distance of the first spacer element and the second spacer element, and the maximum thickness of the first spacer element, the system aberration is balanced, the convergence degree of the entering light by the first two lenses is improved, the field of view angle is improved, the overall length of the lens is controlled, and the small size of the lens is ensured.

[0064] In the example embodiment, the imaging system satisfies: 3.5 < (D2s-d2s+D2m) / (T23+CT2) < 9.5, where D2s is the outer diameter of the object side surface of the second spacer element, d2s is the inner diameter of the object side surface of the second spacer element, D2m is the outer diameter of the image side surface of the second spacer element, T23 is the air gap of the second lens and the third lens on the optical axis, and CT2 is the center thickness of the second lens. Further, the imaging system satisfies: 4.0 < (D2s-d2s+D2m) / (T23+CT2) < 9.0. By reasonably controlling the ratio between the difference between the outer diameter of the object side surface of the second spacer element and the inner diameter of the object side surface of the second spacer element and the sum of the outer diameter of the image side surface of the second spacer element and the center thickness of the second lens and the sum of the air gap of the second lens and the third lens on the optical axis, the second spacer element can be better matched with the inner diameter of the lens barrel; in addition, the axial placement space of the second spacer element can be reasonably arranged, which helps to improve the imaging quality.

[0065] In the example embodiment, the imaging system satisfies: -13.0 < (D3m d3s) / (T34 R7) < 7.5, where D3m is the outer diameter of the image side surface of the third spacer element, d3s is the inner diameter of the object side surface of the third spacer element, T34 is the air gap of the third lens and the fourth lens on the optical axis, and R7 is the curvature radius of the object side surface of the fourth lens. Further, the imaging system satisfies: -12.5 < (D3m d3s) / (T34 R7) < 7.0. By reasonably setting the ratio between the product of the inner diameter of the object side surface and the outer diameter of the image side surface of the third spacer element and the product of the air gap of the third lens and the fourth lens on the optical axis and the curvature radius of the object side surface of the fourth lens, the light rays emitted by the third lens can be blocked, the excess light rays entering the fourth lens can be effectively reduced, and the distribution uniformity of the light rays reaching the imaging surface can be effectively controlled, thereby effectively controlling the dispersion of the Modulation Transfer Function (MTF) curve of the imaging system and obtaining good imaging quality.

[0066] In the example embodiment, the imaging system satisfies: 4.5 < R8 / f+d4s / EP34 < 8.5, where R8 is the curvature radius of the image side surface of the fourth lens, f is the total effective focal length of the imaging system, d4s is the inner diameter of the object side surface of the fourth spacer element, and EP34 is the effective focal length of the fourth lens. Distance of third and fourth spacer elementsFurther, the imaging system satisfies: 5.0 < R8 / f + d4s / EP34 < 8.0. By reasonably controlling the sum relationship between the ratio of the curvature radius of the image side surface of the fourth lens to the total effective focal length of the imaging system and the ratio of the inner diameter of the object side surface of the fourth spacer element to the distance between the third spacer element and the fourth spacer element, the system sensitivity is reduced, and the ghost light generated by the fourth lens edge light leakage is reduced.

[0067] In the example embodiment, the imaging system satisfies: 0 < (D4s + d4s) / (R7 - R8) < 19.5, where D4s is the outer diameter of the object side surface of the fourth spacer element, d4s is the inner diameter of the object side surface of the fourth spacer element, R7 is the curvature radius of the object side surface of the fourth lens, and R8 is the curvature radius of the image side surface of the fourth lens. Further, the imaging system satisfies: 0 < (D4s + d4s) / (R7 - R8) < 19.0. By reasonably setting the ratio of the sum of the inner and outer diameters of the object side surface of the fourth spacer element to the difference between the curvature radii of the object side surface and the image side surface of the fourth lens, the shape of the fourth lens can be controlled, which is beneficial for lens forming; at the same time, the fourth spacer element and the fourth lens have a good bearing relationship, and the assembly yield is improved.

[0068] In the example embodiment, the imaging system satisfies: 53.0 < D5m / T56 + d4m / T45 < 74.0, where D5m is the outer diameter of the image side surface of the fifth spacer element, T56 is the air gap of the fifth lens and the sixth lens on the optical axis, d4m is the inner diameter of the image side surface of the fourth spacer element, and T45 is the air gap of the fourth lens and the fifth lens on the optical axis. Further, the imaging system satisfies: 53.5 < D5m / T56 + d4m / T45 < 73.5. By reasonably setting the sum relationship between the ratio of the outer diameter of the image side surface of the fifth spacer element to the air gap of the fifth lens and the sixth lens on the optical axis and the ratio of the inner diameter of the image side surface of the fourth spacer element to the air gap of the fourth lens and the fifth lens on the optical axis, the positions of the fourth spacer element and the fifth spacer element in the imaging system can be reasonably set, which is beneficial for obtaining a large field of view and ensuring miniaturization of the imaging system.

[0069] In the example embodiment, the imaging system satisfies: 6.5 < (L - EP15) / (T23 + CT3 + T34) FNO < 9.5, where L is the size of the lens barrel along the optical axis, EP15 is the distance of the first spacer element to the fifth spacer element along the optical axis, T23 is the air gap of the second lens and the third lens on the optical axis, CT3 is the center thickness of the third lens, T34 is the air gap of the third lens and the fourth lens on the optical axis, and FNO is the aperture value of the imaging system. Further, the imaging system satisfies: 7.0 < (L - EP15) / (T23 + CT3 + T34) FNO<9.0. By controlling the product of the ratio of the difference between the size of the lens barrel on the optical axis and the distance of the first interval element to the fifth interval element along the optical axis and the distance of the image side surface of the second lens to the object side surface of the fourth lens along the optical axis, the aperture value of the imaging system, the miniaturization of the imaging system is facilitated and better imaging quality is obtained.

[0070] In an example embodiment, the imaging system satisfies: -11.5 < (D5s+D1s) / (R11-R2) < -6.0, where D5s is the outer diameter of the object side surface of the fifth interval element, D1s is the outer diameter of the object side surface of the first interval element, R11 is the radius of curvature of the object side surface of the sixth lens, and R2 is the radius of curvature of the image side surface of the first lens. Further, the imaging system satisfies: -11.0 < (D5s+D1s) / (R11-R2) < -6.5. By reasonably setting the ratio relationship between the sum of the outer diameter of the object side surface of the fifth interval element and the outer diameter of the object side surface of the first lens and the difference between the radius of curvature of the object side surface of the sixth lens and the radius of curvature of the image side surface of the first lens, the chromatic aberration and distortion of the imaging system are improved, the imaging quality is improved, and the large step difference at the front end and the rear end of the imaging system is effectively avoided, and the stability of the lens is improved.

[0071] In an example embodiment, the imaging system satisfies: -8.0 < (CT3-CT2) / (EP23-EP12) < 12.0, where CT3 is the center thickness of the third lens, CT2 is the center thickness of the second lens, EP23 is the distance along the optical axis between the image side surface of the second interval element and the object side surface of the third interval element, and EP12 is the distance between the first interval element and the second interval element. Further, the imaging system satisfies: -8.0 < (CT3-CT2) / (EP23-EP12) < 11.5. By reasonably controlling the difference between the center thickness of the third lens and the center thickness of the second lens, the distance along the optical axis between the second interval element and the third interval element, and the sum of the distance along the optical axis between the first interval element and the second interval element, the internal space of the imaging system is reasonably distributed, and the field curvature is improved by adjusting the distance between adjacent interval elements among the first interval element to the third interval element, and the imaging performance is improved.

[0072] In an example embodiment, the imaging system satisfies: 7.5 < |(R9+R10) / (CP5+CP4)| < 93.5, where R9 is the curvature radius of the object side surface of the fifth lens, R10 is the curvature radius of the image side surface of the fifth lens, CP5 is the maximum thickness of the fifth spacer element, and CP4 is the maximum thickness of the fourth spacer element. Further, the imaging system satisfies: 8.0 < |(R9+R10) / (CP5+CP4)| < 93.0. By controlling the ratio of the sum of the curvature radius of the object side surface and the image side surface of the fifth lens to the sum of the maximum thickness of the fourth spacer element and the fifth spacer element, the shape of the fifth lens can be effectively controlled, which is beneficial for the processing and forming of the lens, and the stray light can be improved.

[0073] In an example embodiment, the imaging system satisfies: 0 < (R3+R4) / (D2s-D1s) < 16.5, where R3 is the curvature radius of the object side surface of the second lens, R4 is the curvature radius of the image side surface of the second lens, D2s is the outer diameter of the object side surface of the second spacer element, and D1s is the outer diameter of the object side surface of the first spacer element. Further, the imaging system satisfies: 0.5 < (R3+R4) / (D2s-D1s) < 16.0. By controlling the ratio of the sum of the curvature radius of the object side surface and the image side surface of the second lens to the difference between the outer diameter of the object side surface of the second spacer element and the outer diameter of the object side surface of the first spacer element, the bending degree of the second lens can be effectively reduced, the risk of forming and appearance of the lens can be reduced, and the large assembly difference at the second lens can be avoided, and the stability of the lens can be improved.

[0074] In an example embodiment, the material of the fourth lens is glass, and the material of any one of the first lens to the third lens and the fifth lens and the sixth lens is plastic. The fourth lens is made of glass, which has a high Abbe number and a high refractive index, and can reduce the size of the lens group. Any one of the first lens to the third lens and the fifth lens and the sixth lens is made of plastic, which is beneficial for saving the cost of the lens group, thereby reducing the cost of the imaging system, and is beneficial for reducing the processing difficulty of the lens while obtaining high imaging quality. In an example embodiment, the lens group according to the present application can further include a filter for correcting color deviation and / or a protective glass for protecting the photosensitive element located on the imaging surface.

[0075] In the embodiments of the present application, at least one of the mirror surfaces of each of the first lens to the sixth lens is an aspherical mirror surface. The aspherical lens is characterized in that the curvature continuously changes from the center of the lens to the periphery of the lens. Unlike the spherical lens having a constant curvature from the center of the lens to the periphery of the lens, the aspherical lens has a better curvature radius characteristic, and has the advantages of improving the distortion aberration and improving the astigmatism aberration. After the aspherical lens is used, the aberration occurring during imaging can be eliminated as much as possible, and thus the imaging quality is improved. Alternatively, the object side surface and the image side surface of each of the first lens to the sixth lens are aspherical mirror surfaces.

[0076] However, those skilled in the art should understand that the number of lenses constituting the imaging system can be changed without departing from the technical solutions claimed by the present application, to obtain the various results and advantages described in the present specification. For example, although the five lenses are described as an example in the embodiments, the imaging system is not limited to including six lenses. If necessary, the imaging system can also include other numbers of lenses.

[0077] The specific embodiments of the imaging system applicable to the above-described embodiments are further described below with reference to the accompanying drawings.

[0078] Example 1

[0079] The following refers to Figures 2 to 5C The imaging system according to Embodiment 1 of the present application is described. Figures 2 to 4 The sectional views of the imaging system 110, the imaging system 120 and the imaging system 130 according to Embodiment 1 of the present application are respectively shown.

[0080] As Figures 2 to 4 shown, the imaging system 110, the imaging system 120 and the imaging system 130 respectively include a lens group including, in order from the object side to the image side along the optical axis, the first lens E1, the stop STO, the second lens E2, the third lens E3, the fourth lens E4, the fifth lens E5, the sixth lens E6, the filter E7 and the imaging surface S15.

[0081] The first lens E1 has negative focal power, with a convex object side surface S1 and a concave image side surface S2. The second lens E2 has positive focal power, with a convex object side surface S3 and a convex image side surface S4. The third lens E3 has negative focal power, with a concave object side surface S5 and a convex image side surface S6. The fourth lens E4 has positive focal power, with a convex object side surface S7 and a convex image side surface S8. The fifth lens E5 has negative focal power, with a concave or convex object side surface S9 and a convex image side surface S10. The sixth lens E6 has negative focal power, with a convex object side surface S11 and a concave image side surface S12. The filter E7 has an object side surface S13 and an image side surface S14. Light from an object passes through the surfaces S1 to S14 in sequence and is finally imaged on the image plane S15.

[0082] Table 1 shows a basic parameter table of the imaging system of Example 1, where the units of the radius of curvature, thickness / distance and focal length are all millimeters (mm).

[0083]

[0084] Table 1

[0085] In this example, the total effective focal length f of the imaging system is 2.17 mm, the distance TTL from the object side surface S1 of the first lens E1 to the image plane S15 on the optical axis is 4.91 mm, the maximum half field angle Semi-FOV of the imaging system is 55.30°, and the aperture value FNO of the imaging system is 2.21.

[0086] In this example, the surface types of the aspheres contained in the object side surfaces and the image side surfaces of the lenses in the first lens E1 to the sixth lens E6 The aspheres can be defined using, but not limited to, the following asphere formula:

[0087] (1)

[0088] wherein, is the sag of the asphere at a height h along the optical axis from the vertex of the asphere; c is the paraxial curvature of the asphere, c = 1 / R (i.e., the paraxial curvature c is the inverse of the radius of curvature R in Table 1 above); k is the conic constant; and Ai is the correction coefficient of the i-th order of the asphere. Table 2 below gives the high order coefficients A4, A6, A8, A10, A12, A14, A16, A18, A20, A22, A24, A26, A28 and A30 that can be used for each of the aspheres S1 to S12 in the lenses of Example 1.

[0089]

[0090] Table 2

[0091] As Figures 2 to 4As shown, the imaging system 110, the imaging system 120 and the imaging system 130 further respectively include a plurality of spacer elements and a lens barrel P0 for accommodating the lens group and the plurality of spacer elements. The plurality of spacer elements, for example, include spacer elements P1~P5. Optionally, P1~P5 and the lens barrel P0 for accommodating the lens group and the spacer elements P1~P5. The first spacer element P1 is located between the first lens E1 and the second lens E2, and the first spacer element P1 and the image side surface S2 of the first lens E1 are partially in contact; the second spacer element P2 is located between the first lens E2 and the second lens E3, and the second spacer element P2 and the image side surface S4 of the second lens E2 are partially in contact; the third spacer element P3 is located between the third lens E3 and the fourth lens E4, and the third spacer element P3 and the image side surface S6 of the third lens E3 are partially in contact; the fourth spacer element P4 is located between the fourth lens E4 and the fifth lens E5, and the fourth spacer element P4 and the image side surface S8 of the fourth lens E4 are partially in contact; the fifth spacer element P5 is located between the fifth lens E5 and the sixth lens E6, and the fifth spacer element P5 and the image side surface S10 of the fifth lens E5 are partially in contact.

[0092] In the imaging system as shown in Figures 2 to 4 The first spacer element P1 to the fifth spacer element P5 can block the external stray light from entering, make the lens better abut against the lens barrel, and enhance the structural stability of the imaging system.

[0093] Table 3 shows the basic parameter table of the lens barrel and the spacer elements of the three imaging systems of Example 1, and the units of the parameters in Table 3 are millimeters (mm).

[0094]

[0095] Table 3

[0096] Figure 5A The axial chromatic aberration curve of the imaging system of Example 1 is shown, which represents the convergence focus deviation of light rays of different wavelengths after passing through the imaging system. Figure 5B The magnification chromatic aberration curve of the imaging system of Example 1 is shown, which represents the deviation of the image height of the light rays on the imaging surface after passing through the lens. Figure 5C The astigmatism curve of the imaging system of Example 1 is shown, which represents the meridional image surface curvature and the sagittal image surface curvature. According to Figures 5A to 5C It can be known that the imaging system given in Example 1 can achieve good imaging quality.

[0097] Example 2

[0098] The imaging system according to Example 2 of the present application is described below with reference to Figures 6 to 9C Figures 6 to 8 ​Cross-sectional schematic diagrams of the imaging system 210, the imaging system 220 and the imaging system 230 according to the embodiment 2 of the present application are shown respectively.

[0099] As shown in FIG. 2, the imaging system 110, the imaging system 120 and the imaging system 130 respectively include a lens group which sequentially includes a first lens E1, a stop STO, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a filter E7 and an imaging surface S15 along an optical axis from an object side to an image side. Figures 6 to 8

[0100] The first lens E1 has a negative focal power, and its object side surface S1 is a concave surface, and its image side surface S2 is a concave surface. The second lens E2 has a positive focal power, and its object side surface S3 is a convex surface, and its image side surface S4 is a convex surface. The third lens E3 has a negative focal power, and its object side surface S5 is a concave surface, and its image side surface S6 is a concave surface. The fourth lens E4 has a positive focal power, and its object side surface S7 is a convex surface, and its image side surface S8 is a convex surface. The fifth lens E5 has a negative focal power, and its object side surface S9 is a convex surface, and its image side surface S10 is a concave surface. The sixth lens E6 has a negative focal power, and its object side surface S11 is a convex surface, and its image side surface S12 is a concave surface. The filter E7 has an object side surface S13 and an image side surface S14. Light from an object sequentially passes through the surfaces S1 to S14 and is finally imaged on the imaging surface S15.

[0101] Table 4 shows a basic parameter table of the imaging system of the embodiment 2, wherein the units of the curvature radius, the thickness / distance and the focal length are all millimeter (mm).

[0102]

[0103] Table 4

[0104] In the embodiment, the total effective focal length f of the imaging system is 2.27 mm, the distance TTL of the object side surface S1 of the first lens E1 to the imaging surface S15 on the optical axis is 4.89 mm, the maximum half field angle Semi-FOV of the imaging system is 53.52°, and the aperture value FNO of the imaging system is 2.22.

[0105] Table 5 shows the high order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, A20, A22, A24, A26, A28 and A30 of each mirror surface of the aspheric surfaces S1 to S12 which can be used in the embodiment 2, wherein each aspheric surface profile can be defined by the formula (1) given in the embodiment 1 above.

[0106]

[0107] Table 5

[0108] As shown in FIG. 2, the imaging system 110, the imaging system 120 and the imaging system 130 respectively include a lens group which sequentially includes a first lens E1, a stop STO, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a filter E7 and an imaging surface S15 along an optical axis from an object side to an image side. Figures 6 to 8 ​As shown, imaging systems 210, 220, and 230 each further include multiple spacer elements and a lens barrel P0 for accommodating the lens group and the multiple spacer elements. These multiple spacer elements include, for example, spacer elements P1 to P5. Optionally, the first spacer element P1 is located between the first lens E1 and the second lens E2, and the first spacer element P1 is in contact with the image-side surface S2 of the first lens E1; the second spacer element P2 is located between the first lens E2 and the second lens E3, and the second spacer element P2 is in contact with the image-side surface S4 of the second lens E2; the third spacer element P3 is located between the third lens E3 and the fourth lens E4, and the third spacer element P3 is in contact with the image-side surface S6 of the third lens E3; the fourth spacer element P4 is located between the fourth lens E4 and the fifth lens E5, and the fourth spacer element P4 is in contact with the image-side surface S8 of the fourth lens E4; the fifth spacer element P5 is located between the fifth lens E5 and the sixth lens E6, and the fifth spacer element P5 is in contact with the image-side surface S10 of the fifth lens E5.

[0109] For example, the plurality of spacers may also include a spacer P2' located between the second spacer P2 and the third lens E3, and a spacer P4' located between the fourth spacer P4 and the fifth lens E5. Alternatively, spacer P2' may partially contact the second spacer P2 and the third lens E3, respectively, and spacer P4' may partially contact the fourth spacer P4 and the fifth lens E5, respectively.

[0110] In such Figures 6 to 8 In the imaging system shown, the first spacer element P1 to the fifth spacer element P5 can block excess external light from entering, allowing the lens and lens barrel to better support each other and enhancing the structural stability of the imaging system.

[0111] Table 6 shows the basic parameters of the lens barrel and spacer element of the three imaging systems in Example 2. The unit of each parameter in Table 6 is millimeters (mm).

[0112]

[0113] Table 6

[0114] Figure 9A The on-axis chromatic aberration curve of the imaging system of Embodiment 2 is shown, which represents the deviation of the convergence focal point after light of different wavelengths passes through the imaging system. Figure 9B The magnification chromatic aberration curve of the imaging system of Embodiment 2 is shown, which represents the deviation of different image heights on the imaging plane after light passes through the lens. Figure 9C The astigmatism curves of the imaging system of Example 2 are shown, representing the meridional image plane curvature and the sagittal image plane curvature. According to... Figures 9A to 9CIt can be seen that the imaging system given in Example 2 can achieve good imaging quality.

[0115] Example 3

[0116] The following is for reference Figures 10 to 13C An imaging system according to Embodiment 3 of this application is described. Figures 10 to 12 Cross-sectional schematic diagrams of imaging systems 310, 320 and 330 according to Embodiment 3 of this application are shown respectively.

[0117] like Figures 10 to 12 As shown, imaging systems 310, 320 and 330 each include a lens group, which includes, in sequence along the optical axis from the object side to the image side: a first lens E1, an aperture stop STO, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a sixth lens E6, a filter E7 and an imaging surface S15.

[0118] The first lens E1 has negative optical power, with its object-side surface S1 being concave and its image-side surface S2 being concave. The second lens E2 has positive optical power, with its object-side surface S3 being convex and its image-side surface S4 being convex. The third lens E3 has negative optical power, with its object-side surface S5 being concave and its image-side surface S6 being concave. The fourth lens E4 has negative optical power, with its object-side surface S7 being concave and its image-side surface S8 being convex. The fifth lens E5 has positive optical power, with its object-side surface S9 being convex and its image-side surface S10 being concave. The sixth lens E6 has negative optical power, with its object-side surface S11 being convex and its image-side surface S12 being concave. The filter E7 has an object-side surface S13 and an image-side surface S14. Light from the object passes sequentially through each surface S1 to S14 and is finally imaged on the imaging surface S15.

[0119] Table 7 shows the basic parameters of the imaging system of Example 3, where the units for radius of curvature, thickness / distance, and focal length are millimeters (mm).

[0120]

[0121] Table 7

[0122] In this embodiment, the total effective focal length f of the imaging system is 2.17 mm, the distance TTL between the object surface S1 and the imaging surface S15 of the first lens E1 on the optical axis is 4.97 mm, the maximum semi-FOV of the imaging system is 53.53°, and the aperture value FNO of the imaging system is 2.22.

[0123] Table 8 shows the high-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, A20, A22, A24, A26, A28 and A30 of each mirror surface in the aspherical surfaces S1 to S12 used in the embodiment 3, wherein each aspherical surface can be defined by the formula (1) given in the embodiment 1 above.

[0124]

[0125] Table 8

[0126] As Figures 10 to 12 shown, the imaging system 310, the imaging system 320 and the imaging system 330 each further include a plurality of spacer elements, and a lens barrel P0 for accommodating the lens group and the plurality of spacer elements. The plurality of spacer elements, for example, include the spacer elements P1 to P5. Optionally, the first spacer element P1 is located between the first lens E1 and the second lens E2, and the first spacer element P1 partially contacts the image side surface S2 of the first lens E1; the second spacer element P2 is located between the first lens E2 and the second lens E3, and the second spacer element P2 partially contacts the image side surface S4 of the second lens E2; the third spacer element P3 is located between the third lens E3 and the fourth lens E4, and the third spacer element P3 partially contacts the image side surface S6 of the third lens E3; the fourth spacer element P4 is located between the fourth lens E4 and the fifth lens E5, and the fourth spacer element P4 partially contacts the image side surface S8 of the fourth lens E4; and the fifth spacer element P5 is located between the fifth lens E5 and the sixth lens E6, and the fifth spacer element P5 partially contacts the image side surface S10 of the fifth lens E5.

[0127] Exemplarily, the plurality of spacer elements, for example, further include a spacer element P1' located between the first spacer element P1 and the second lens E2. As an option, the spacer element P1' can partially contact the first spacer element P1 and the second lens E2, respectively.

[0128] In the imaging system as Figures 10 to 12 shown, the first spacer element P1' to the fifth spacer element P5 can block the external stray light from entering, make the lens better abut against the lens barrel, and enhance the structural stability of the imaging system.

[0129] Table 9 shows the basic parameter table of the lens barrel and the spacer elements of the three imaging systems in the embodiment 3, wherein the units of each parameter in Table 9 are millimeters (mm).

[0130]

[0131] Table 9

[0132] Figure 13AThe on-axis chromatic aberration curve of the imaging system of embodiment 3 is shown, which represents the convergence point deviation of light rays of different wavelengths after passing through the imaging system. Figure 13B The magnification chromatic aberration curve of the imaging system of embodiment 3 is shown, which represents the deviation of different image heights of light rays on the imaging plane after passing through the lens. Figure 13C The astigmatism curve of the imaging system of embodiment 3 is shown, which represents the meridional image curvature and sagittal image curvature. According to the astigmatism curve, the maximum sagittal image curvature is 0.005 mm-1, and the maximum meridional image curvature is 0.005 mm-1. Figures 13A to 13C It can be seen that the imaging system given in embodiment 3 can achieve good imaging quality.

[0133] In summary, embodiments 1 to 3 respectively satisfy the relationships shown in Table 10, wherein the system numbers of the imaging systems in embodiments 1 to 3 are given in Table 10.

[0134]

[0135] Table 10

[0136] The above description is merely preferred embodiments of the present application and a description of the technical principles of the application. It should be understood by those skilled in the art that the scope of the application disclosed in the present application is not limited to the technical solutions formed by the specific combinations of the above technical features, and should also cover other technical solutions formed by any combinations of the above technical features or equivalent features without departing from the inventive concept. For example, the above features can be replaced with technical features disclosed in the present application (but not limited to) having similar functions to form technical solutions.

Claims

1. An imaging system, comprising a lens group, a plurality of spacer elements, and a lens barrel for housing the lens group and the plurality of spacer elements, characterized in that, The lens group comprises, in sequence along the optical axis from the object side to the image side, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens, wherein the first lens and the third lens have negative optical power, the second lens has positive optical power, and the number of lenses with optical power in the lens group is six. The plurality of spacer elements include: The third spacer element contacts the image-side portion of the third lens; and The fourth spacer element is in contact with the image-side portion of the fourth lens; The imaging system satisfies: 6.36 ≤ (D4s - CP4) N4 / CT4≤11.02 and 5.92≤R8 / f+d4s / EP34≤7.41, where D4s is the outer diameter of the object side of the fourth spacer element, CP4 is the maximum thickness of the fourth spacer element, N4 is the refractive index of the fourth lens, CT4 is the center thickness of the fourth lens, R8 is the radius of curvature of the image side of the fourth lens, f is the total effective focal length of the imaging system, d4s is the inner diameter of the object side of the fourth spacer element, and EP34 is the distance between the third spacer element and the fourth spacer element.

2. The imaging system according to claim 1, characterized in that, The imaging system satisfies: -12.05≤(D3m d3s) / (T34 R7)≤6.32, Wherein, D3m is the outer diameter of the image side of the third spacer element, d3s is the inner diameter of the object side of the third spacer element, T34 is the air gap between the third lens and the fourth lens on the optical axis, and R7 is the radius of curvature of the object side of the fourth lens.

3. The imaging system according to claim 1, characterized in that, The imaging system satisfies: 0.20≤(D4s+d4s) / (R7-R8)≤18.14, Wherein, D4s is the outer diameter of the object side of the fourth spacer element, d4s is the inner diameter of the object side of the fourth spacer element, R7 is the radius of curvature of the object side of the fourth lens, and R8 is the radius of curvature of the image side of the fourth lens.

4. The imaging system according to claim 1, characterized in that, The plurality of spacer elements further includes: a second spacer element that contacts the image-side portion of the second lens, wherein the imaging system satisfies: -23.60≤(f3+f2) / (EP23-CP2)≤-4.01, Wherein, f3 is the effective focal length of the third lens, f2 is the effective focal length of the second lens, EP23 is the distance along the optical axis between the image side of the second spacer and the object side of the third spacer, and CP2 is the maximum thickness of the second spacer.

5. The imaging system according to claim 1, characterized in that, The plurality of spacers further includes: a first spacer element that contacts the image-side portion of the first lens, wherein the imaging system satisfies: 1.11≤(D1m-d1m) / R2 / (CP1 / T12)≤19.96, Wherein, D1m is the outer diameter of the image side of the first spacer element, d1m is the inner diameter of the image side of the first spacer element, R2 is the radius of curvature of the image side of the first lens, CP1 is the maximum thickness of the first spacer element, and T12 is the air gap between the first lens and the second lens on the optical axis.

6. The imaging system according to claim 1, characterized in that, The plurality of spacers further includes: a first spacer element that contacts the image-side surface portion of the first lens; and a second spacer element that contacts the image-side surface portion of the second lens, wherein the imaging system satisfies: 5.09≤(R2+R3) / (CT2-EP12+CP1)≤26.28, Wherein, R2 is the radius of curvature of the image side of the first lens, R3 is the radius of curvature of the object side of the second lens, CT2 is the center thickness of the second lens, EP12 is the distance between the first spacer element and the second spacer element, and CP1 is the maximum thickness of the first spacer element.

7. The imaging system according to claim 1, characterized in that, The plurality of spacer elements further includes: a second spacer element that contacts the image-side portion of the second lens, wherein the imaging system satisfies: 4.67≤(D2s-d2s+D2m) / (T23+CT2)≤8.50, Wherein, D2s is the outer diameter of the object side of the second spacer element, d2s is the inner diameter of the object side of the second spacer element, D2m is the outer diameter of the image side of the second spacer element, T23 is the air gap between the second lens and the third lens on the optical axis, and CT2 is the center thickness of the second lens.

8. The imaging system according to claim 1, characterized in that, The plurality of spacers further includes a fifth spacer element, which contacts the image-side portion of the fifth lens, wherein the imaging system satisfies: 54.39≤D5m / T56+d4m / T45≤73.32, Wherein, D5m is the outer diameter of the image-side surface of the fifth spacer element, T56 is the air gap between the fifth lens and the sixth lens on the optical axis, d4m is the inner diameter of the image-side surface of the fourth spacer element, and T45 is the air gap between the fourth lens and the fifth lens on the optical axis.

9. The imaging system according to claim 1, characterized in that, The plurality of spacers further includes: a first spacer element that contacts the image-side surface portion of the first lens; and a fifth spacer element that contacts the image-side surface portion of the fifth lens, wherein the imaging system satisfies: -10.32≤(D5s+D1s) / (R11-R2)≤-7.21, Wherein, D5s is the outer diameter of the object side of the fifth spacer element, D1s is the outer diameter of the object side of the first spacer element, R11 is the radius of curvature of the object side of the sixth lens, and R2 is the radius of curvature of the image side of the first lens.

10. The imaging system according to claim 1, characterized in that, The plurality of spacers further includes: a first spacer element that contacts the image-side surface portion of the first lens; and a second spacer element that contacts the image-side surface portion of the second lens, wherein the imaging system satisfies: -7.95≤(CT3-CT2) / (EP23-EP12)≤11.27, Wherein, CT3 is the center thickness of the third lens, CT2 is the center thickness of the second lens, EP23 is the distance along the optical axis between the image side of the second spacer and the object side of the third spacer, and EP12 is the distance between the first spacer and the second spacer.

11. The imaging system according to claim 1, characterized in that, The plurality of spacers further includes a fifth spacer element, which contacts the image-side portion of the fifth lens, wherein the imaging system satisfies: 8.79≤|(R9+R10) / (CP5+CP4)|≤92.71, Wherein, R9 is the radius of curvature of the object side of the fifth lens, R10 is the radius of curvature of the image side of the fifth lens, CP5 is the maximum thickness of the fifth spacer element, and CP4 is the maximum thickness of the fourth spacer element.

12. The imaging system according to claim 1, characterized in that, The plurality of spacers further includes: a first spacer element that contacts the image-side surface portion of the first lens; and a second spacer element that contacts the image-side surface portion of the second lens, wherein the imaging system satisfies: 0.91≤(R3+R4) / (D2s-D1s)≤15.17, Wherein, R3 is the radius of curvature of the object side of the second lens, R4 is the radius of curvature of the image side of the second lens, D2s is the outer diameter of the object side of the second spacer element, and D1s is the outer diameter of the object side of the first spacer element.

13. The imaging system according to claim 1, characterized in that, The plurality of spacer elements also include: The first spacer element is in contact with the image-side portion of the first lens; The second spacer element contacts the image-side portion of the second lens; and The fifth spacer element is in contact with the image-side portion of the fifth lens.

14. The imaging system according to claim 13, characterized in that, The dimension of the lens barrel along the optical axis is less than 5.0 mm; and The imaging system satisfies: 615.19 ≤ (L + TD) tan(Semi-FOV) / CPmin≤721.59, where L is the dimension of the lens barrel along the optical axis, TD is the distance from the object side of the first lens to the image side of the sixth lens along the optical axis, Semi-FOV is the maximum half field of view of the imaging system, and CPmin is the minimum of the maximum thicknesses of the spacers from the first spacer to the fifth spacer.

15. The imaging system according to claim 13, characterized in that, The outer diameter of the object side of any one of the at least two spacers included in the first to the fifth spacers is equal to the outer diameter of the image side, and the inner diameter of the object side of any one spacer is equal to the inner diameter of the image side.

16. The imaging system according to claim 13, characterized in that, The imaging system satisfies: 7.48≤(L-EP15) / (T23+CT3+T34) FNO ≤ 8.37 Wherein, L is the dimension of the lens barrel along the optical axis, EP15 is the distance from the first spacer element to the fifth spacer element along the optical axis, T23 is the air gap between the second lens and the third lens on the optical axis, CT3 is the center thickness of the third lens, T34 is the air gap between the third lens and the fourth lens on the optical axis, and FNO is the aperture value of the imaging system.

17. The imaging system according to any one of claims 1-16, characterized in that, The imaging system satisfies: -1.89≤R3 / R4≤-1.40, Wherein, R3 is the radius of curvature of the object side of the second lens, and R4 is the radius of curvature of the image side of the second lens.

18. The imaging system according to any one of claims 1-16, characterized in that, The imaging system satisfies: -3.00≤f4 / f5≤-0.40, and -3.53≤R8 / R11≤-1.63; Wherein, f4 is the effective focal length of the fourth lens, f5 is the effective focal length of the fifth lens, R8 is the radius of curvature of the image side of the fourth lens, and R11 is the radius of curvature of the object side of the sixth lens.

19. The imaging system according to any one of claims 1-16, characterized in that, The fourth lens is made of glass.

20. The imaging system according to any one of claims 1-16, characterized in that, The image-side surface of the first lens is concave; The object-side surface of the second lens is convex, and the image-side surface is also convex. The object-side surface of the third lens is concave. The image-side surface of the fourth lens is convex; and The object-side surface of the sixth lens is convex, and the image-side surface is concave.

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