CN218886278U - Imaging system - Google Patents

Abstract

The application discloses imaging system, this imaging system includes lens group and a plurality of interval component, and lens group includes by the thing side to the image side according to the preface along the optical axis: a first lens having positive refractive power; the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; a third lens element with negative refractive power having a concave object-side surface and a concave image-side surface; a fourth lens element with positive refractive power; a fifth lens, the object side surface of which is a concave surface and the image side surface of which is a convex surface; wherein the plurality of spacer elements includes at least one spacer element between the first optic and the second optic including a first spacer element and a second spacer element, and the imaging system satisfies: 2< (D2 s-D2 s)/(D1 s-D1 s) + (f 1 tan (Semi-FOV)) <10, wherein D1s is the inner diameter of the object-side face of the first spacer element, D1s is the outer diameter of the object-side face of the first spacer element, D2s is the inner diameter of the object-side face of the second spacer element, D2s is the outer diameter of the object-side face of the second spacer element, f1 is the effective focal length of the first lens, and Semi-FOV is half of the maximum field angle of the lens group.

Description

Imaging system

Technical Field

The present application relates to the field of optical elements, and in particular, to an imaging system.

Background

As the performance of charge-coupled devices (CCDs) and complementary metal-oxide semiconductor (CMOS) image sensors increases and the size thereof decreases, the corresponding imaging system also meets the requirements of high imaging quality and miniaturization.

With the increasing requirements of imaging systems of portable electronic products, the number of lenses or the longer focal length of the imaging system is increased to meet the requirements of optical performance, but the miniaturization and light weight of the imaging system are not facilitated. The imaging system may also typically include a spacing element for coupling adjacent lenses, with larger segments between the lenses being susceptible to poor set stability of the imaging system; with the increase of the image surface, the edge of the lens is easy to generate the stray light phenomenon, and the imaging quality is reduced. Whether the imaging light beam of the imaging system has stray light or not and the assembling stability of a plurality of lenses are key indexes for measuring the imaging performance.

Therefore, how to reasonably set the optical parameters of the imaging system and the structure and size of the spacing element to improve the imaging quality and the assembly stability of the imaging system is an urgent problem to be solved in the art.

SUMMERY OF THE UTILITY MODEL

The present application provides an imaging system, comprising a lens assembly and a plurality of spacer elements, the lens assembly sequentially comprises from an object side to an image side along an optical axis: a first lens having positive refractive power; the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; a third lens element with negative refractive power having a concave object-side surface and/or concave image-side surface; a fourth lens element with positive refractive power; a fifth lens, the object side surface of which is a concave surface and the image side surface of which is a convex surface; wherein the plurality of spacer elements comprises at least one spacer element located between any two adjacent lenses, wherein the at least one spacer element is in contact with at least a portion of a lens located on an object side thereof, and the at least one spacer element located between the first lens and the second lens comprises a first spacer element and a second spacer element, and the imaging system satisfies: 2< (D2 s-D2 s)/(D1 s-D1 s) + (f 1 tan (Semi-FOV)) <10, wherein D1s is an inner diameter of an object-side face of the first spacer element, D1s is an outer diameter of an object-side face of the first spacer element, D2s is an inner diameter of an object-side face of the second spacer element, D2s is an outer diameter of an object-side face of the second spacer element, f1 is an effective focal length of the first lens, and Semi-FOV is half of a maximum field angle of the lens group. In one embodiment of the present application, at least a portion of the first and second spacing elements are in contact with at least a portion of the object side surfaces of the first and second lenses, respectively.

In one embodiment of the present application, an inner diameter D1s of the object-side surface of the first spacer element, an outer diameter D1s of the object-side surface of the first spacer element, an inner diameter D1m of the image-side surface of the first spacer element, an outer diameter D1m of the image-side surface of the first spacer element, a curvature radius R2 of the image-side surface of the first lens, and a curvature radius R3 of the object-side surface of the second lens satisfy: l (R2/R3) + (D1 s/D1 m) | <20.

In one embodiment of the present application, an inner diameter D1s of the object-side surface of the first spacer element, an outer diameter D1s of the object-side surface of the first spacer element, an inner diameter D1m of the image-side surface of the first spacer element, an outer diameter D1m of the image-side surface of the first spacer element, a curvature radius R2 of the image-side surface of the first lens, and a curvature radius R3 of the object-side surface of the second lens satisfy: l (R2 + D1 s)/(R3 + D1 m) | <4.

In one embodiment of the present application, the plurality of spacer elements further comprises a third spacer element positioned between the second lens piece and the third lens piece, wherein an object-side surface of the third spacer element is in contact with at least a portion of an image-side surface of the second lens piece and an image-side surface of the third spacer element is in contact with at least a portion of an object-side surface of the third lens piece; and the imaging system satisfies: 25< (d 2s + d3 s)/(R3 + R4) × V2<60, wherein d2s is the inner diameter of the object-side surface of the second spacing element, d3s is the inner diameter of the object-side surface of the third spacing element, R3 is the radius of curvature of the object-side surface of the second optic, R4 is the radius of curvature of the image-side surface of the second optic, and V2 is the abbe number of the second optic.

In one embodiment of the present application, the plurality of spacer elements further comprises a third spacer element positioned between the second lens plate and the third lens plate, wherein an object side surface of the third spacer element is in contact with at least a portion of an image side surface of the second lens plate and an image side surface of the third spacer element is in contact with at least a portion of an object side surface of the third lens plate; and the imaging system satisfies: 1< -d3s tan (Semi-FOV)/T23 <5, wherein D3s is the outer diameter of the object-side face of the third spacer element, semi-FOV is half of the maximum field angle of the lens group, and T23 is the distance between the second lens piece and the third lens piece on the optical axis.

In one embodiment of the present application, a distance EP23 of the second spacer element from the third spacer element on the optical axis and a center thickness CT2 of the second lens on the optical axis satisfy: 0< -EP23/CT 2<3.

In one embodiment of the present application, the plurality of spacer elements further comprises a fourth spacer element located between the third lens and the fourth lens, wherein a distance EP34 of the third spacer element from the fourth spacer element on the optical axis satisfies a central thickness CT3 of the third lens on the optical axis: 0-straw EP34/CT3<3.

In one embodiment of the present application, the plurality of spacer elements further comprises a fifth spacer element located between the fourth lens and the fifth lens, wherein a distance EP45 of the fourth spacer element from the fifth spacer element on the optical axis satisfies a central thickness CT4 of the fourth lens on the optical axis: 0< -EP45/CT 4<3.

In one embodiment of the present application, the plurality of spacer elements further includes a fourth spacer element between the third lens and the fourth lens and a fifth spacer element between the fourth lens and the fifth lens, wherein a distance EP45 of the fourth spacer element and the fifth spacer element on the optical axis, a thickness CP4 of the fourth spacer element, a center thickness CT4 of the fourth lens on the optical axis, and a refractive index N4 of the fourth lens satisfy: 1< (EP 45+ CP 4)/CT 4 × N4<5.

In one embodiment of the present application, the plurality of spacer elements further comprises a third spacer element positioned between the second lens and the third lens, wherein a distance EP34 between the third spacer element and the fourth spacer element on the optical axis, a thickness CP4 of the fourth spacer element, a center thickness CT3 of the third lens on the optical axis, and a distance T23 between the second lens and the third lens on the optical axis satisfy: 0< (EP 34+ CP 4)/(CT 3+ T23) <2.

The imaging system of this application includes lens group and a plurality of spacer element, through the internal diameter of adjusting first spacer element and second spacer element and the angle of field relation of lens group, can guarantee the relative illuminance of outer visual field, and then improves the imaging quality. And, through set up at least one spacer element between adjacent lens, reduced the segment difference between the lens, be favorable to improving imaging system's assemblage stability, simultaneously, spacer element still can be used to intercept unnecessary reflection light path to reduce the parasitic light.

Drawings

Other features, objects and advantages of the present application will become more apparent upon reading of the following detailed description of non-limiting embodiments thereof, made with reference to the accompanying drawings in which:

fig. 1 shows a parameter labeling diagram of an imaging lens according to the present application;

figure 2 shows a schematic structural view of a lens group according to example 1 of the present application;

FIG. 3 is a cross-sectional view of an imaging system including the lens group of FIG. 2 according to embodiment 1 of the present application;

FIG. 4 is a cross-sectional view of another imaging system including the set of lenses shown in FIG. 2 according to embodiment 1 of the present application;

FIG. 5 is a cross-sectional view of another imaging system including the lens group shown in FIG. 2 according to embodiment 1 of the present application;

figures 6A-6C show the astigmatism curve, distortion curve and chromatic aberration of a lens array according to example 1 of the present application;

figure 7 shows a schematic view of a structure of a lens set according to example 2 of the present application;

FIG. 8 is a cross-sectional view of an imaging system including the lens group of FIG. 7 according to embodiment 2 of the present application;

FIG. 9 is a cross-sectional view of another imaging system including the set of lenses shown in FIG. 7 according to example 2 of the present application;

FIG. 10 is a cross-sectional view of another imaging system including the set of lenses shown in FIG. 7 according to example 2 of the present application;

11A-11C show the astigmatism curve, distortion curve and chromatic aberration of the lens set according to example 2 of the present application;

figure 12 shows a schematic view of a set of lenses according to example 3 of the present application;

FIG. 13 shows a cross-sectional schematic view of an imaging system including the set of lenses shown in FIG. 12 according to example 3 of the present application;

figure 14 shows a cross-sectional schematic view of another imaging system according to embodiment 3 of the present application including the set of lenses shown in figure 12;

FIG. 15 is a cross-sectional view of another imaging system including the set of lenses shown in FIG. 12 according to example 3 of the present application;

fig. 16A to 16C show an astigmatism curve, a distortion curve and a chromatic aberration of magnification curve of the lens set according to embodiment 3 of the present application, respectively.

Detailed Description

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

In the drawings, the thickness, size and shape of the lenses have been slightly exaggerated for the 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.

Herein, 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 position of the concave surface 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 to be shot 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.

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

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.

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 in the present application may be combined with each other without conflict. The following examples are merely illustrative of several embodiments of the present invention, which are described in more detail and detail, but are not to be construed as limiting the scope of the invention. It should be noted that, for those skilled in the art, without departing from the concept of the present application, several modifications and improvements may be made, which all fall within the protection scope of the present invention, for example, any combination of the lens group, the lens barrel structure and the spacing element may be used in the embodiments of the present application, and the lens group in one embodiment is not limited to be combined with the lens barrel structure, the spacing element and the like in this embodiment. The present application will be described in detail below with reference to the embodiments with reference to the attached drawings.

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

The imaging system according to an exemplary embodiment of the present disclosure may include a lens group and a lens barrel for accommodating the lens group, wherein the lens group includes, in order from an object side to an image side along an optical axis, a first lens element, a second lens element, a third lens element, a fourth lens element and a fifth lens element with refractive power, respectively.

In an exemplary embodiment, the first lens element can have positive refractive power, the object-side surface can be convex, and the image-side surface can be convex or concave, the second lens element can have positive or negative refractive power, the object-side surface can be convex, and the image-side surface can be concave, thereby forming a meniscus shape with the object side convex; the third lens element with negative refractive power has a concave object-side surface and a concave image-side surface; the fourth lens element with positive refractive power has a convex object-side surface and a convex or concave image-side surface; the fifth lens element with positive refractive power has a concave object-side surface and a convex image-side surface, and thus has a meniscus shape convex toward the image side. By reasonably distributing the refractive power of each lens included in the lens group, the imaging system can meet the requirement of long focus; the optical path of the optical path in the optical system can be adjusted by reasonably distributing the surface type of each lens, the manufacturability of lens forming is increased, the resolving power of an imaging system is effectively improved, and the image pickup effect can be effectively improved by reasonably distributing the refractive power and the surface type.

In an exemplary embodiment, the imaging system further comprises a plurality of spacer elements including at least one spacer element located between any adjacent two of the lenses, the at least one spacer element being in contact with at least a portion of an adjacent lens. Optionally, the at least one spacing element may be in contact with a non-active optical portion of an adjacent lens (e.g., an edge region of the lens). Illustratively, the plurality of spacer elements includes, for example, a first spacer element and a second spacer element between the first lens and the second lens, a third spacer element between the second lens and the third lens, a fourth spacer element between the third lens and the fourth lens, and a fifth spacer element between the fourth lens and the fifth lens. Optionally, at least a portion of the first spacer element and at least a portion of the second spacer element are in contact, e.g. the image side surface of the first spacer element is in contact with at least a portion of the object side surface of the second spacer element. The static repulsion of the PC component in the assembling process can be reduced by controlling at least one part of the first spacing element to be in contact with at least one part of the second spacing element, the stability of the lens component in the assembling process is ensured, and the manufacturing yield of the lens is improved. Through setting up a plurality of spacer elements, help intercepting unnecessary reflection light path, promote imaging system's formation of image definition, reduce the production of miscellaneous light, ghost to can guarantee that a plurality of spacer elements assemble with lens cone, lens in order, and guarantee that the assembly is stable.

In an exemplary embodiment, the image side surface of the first lens may be in contact with at least a portion of the object side surface of the first spacer element, the object side surface of the second lens may be in contact with at least a portion of the image side surface of the second spacer element, and the image side surface of the second lens may be in contact with at least a portion of the object side surface of the third spacer element. Through set up second interval component and set up third interval component at the image side of second lens at the object side of second lens, can rationally restrict incident light scope, reject the relatively poor light of marginal quality, reduce off-axis image difference, can shelter from the stray light path that the second lens reflection produced simultaneously, improve optical system's imaging quality. In addition, the contact between the object side surface with the convex surface of the second lens and at least one part of the image side surface of the second spacing element is reasonably controlled, so that the path of a light path in an optical system can be reasonably limited, the manufacturability of lens molding is increased, and the image resolution of an imaging system is effectively improved. Alternatively, the object side surface of the third lens may be in contact with at least a portion of the image side surface of the third spacing element, the image side surface of the third lens may be in contact with at least a portion of the object side surface of the fourth spacing element, the object side surface of the fourth lens may be in contact with at least a portion of the image side surface of the fourth spacing element, the object side surface of the fourth lens may be in contact with at least a portion of the object side surface of the fifth spacing element, and the object side surface of the fifth lens may be in contact with at least a portion of the image side surface of the fifth spacing element.

In an exemplary embodiment, the imaging system further includes a prism disposed within the lens barrel, and the prism may be disposed on an object side surface of the first lens along the optical axis. The prism may have two optical axes that are orthogonal, an incident optical axis perpendicular to the incident surface of the prism and an exit optical axis perpendicular to the exit surface of the prism. The light from the object can sequentially pass through the incident surface of the prism along the incident optical axis, is reflected and deflected by 90 degrees by the reflecting surface of the prism, and then is emitted in the direction vertical to the emitting surface. The emergent optical axis of the prism and the optical axis of the lens group are positioned on the same straight line, and the light emitted from the emergent surface of the prism can sequentially pass through the second lens, the third lens, the fourth lens and the fifth lens and is finally projected onto the imaging surface. The optical axes are fused together to form the main optical axis of the periscopic telephoto lens. Change the reflection direction of light through the prism for the tele lens can lie flat and place (for putting upside down for vertical placing), can realize periscopic structure, thereby reduces the thickness of carrying on the electronic equipment of tele lens.

In an exemplary embodiment, referring to the dimensioning of fig. 1, a distance TD on the optical axis from the object-side surface of the first lens to the image-side surface of the fifth lens, an aperture value Fno of the lens group, an inner diameter d0s of the object-side end of the lens barrel, and an inner diameter d0m of the image-side end of the lens barrel satisfy: 7 Td/(d 0s-d0 m) × Fno <11. The inner diameters of the two ends of the imaging system are controlled by adjusting the difference value of the inner diameters of the object side end and the image side end of the lens cone, so that the overall specification of the imaging system is reduced, and in addition, the system length and the aperture value of the lens group are adjusted to be in relation with the inner diameters of the two ends of the lens cone, so that the imaging system has smaller system length on the premise of ensuring the imaging effect, and the imaging system has the characteristics of miniaturization and ultra-thinness. In some examples, the object side end and the image side end of the lens barrel may have a slope structure as inclined in fig. 1, so that the inner diameter d0s of the object side end and the inner diameter d0m of the image side end of the lens barrel may be understood as the smallest inner diameters that the object side end and the image side end of the lens barrel have.

It is understood that, in order to make the structure and the labels of the drawings clearer, the labels of the sizes of the components in fig. 1 are simplified, only a group of sizes of the first spacing element and the distance between the first spacing element and the second spacing element on the optical axis are taken as examples, and the first spacing element can be referred to for the size limitation of each of the second spacing element to the fifth spacing element, which is not described herein in detail.

In an exemplary embodiment, with reference to the dimensioning of fig. 1, the inner diameter D1s of the object-side face of the first spacer element, the outer diameter D1s of the object-side face of the first spacer element, the inner diameter D2s of the object-side face of the second spacer element, the outer diameter D2s of the object-side face of the second spacer element, the effective focal length f1 of the first lens element and half of the maximum field angle Semi-FOV of the lens group are satisfied: 2< (D2 s-D2 s)/(D1 s-D1 s) + (f 1 tan (Semi-FOV)) <10. The deformation of the assembly stress can be reduced by reasonably controlling the inner diameter of the first spacing element, so that the field curvature sensitivity of the sensitive lens is effectively reduced; the range of satisfying above-mentioned conditional expression can be through the internal diameter of reasonable control second interval component, can guarantee the relative illuminance in outer visual field effectively to can rationally restrict incident light scope, reject the relatively poor light of edge quality, improve imaging system's imaging quality.

In an exemplary embodiment, with reference to the dimensioning of fig. 1, the inner diameter D1s of the object-side face of the first spacer element, the outer diameter D1s of the object-side face of the first spacer element, the inner diameter D1m of the image-side face of the first spacer element, the outer diameter D1m of the image-side face of the first spacer element, the radius of curvature R2 of the image-side face of the first lens and the radius of curvature R3 of the object-side face of the second lens are satisfied: l (R2/R3) + (D1 s/D1 m) + (D1 s/D1 m) | <20. The curvature of the image side surface and the object side surface of the first lens are controlled to be matched with the inner diameter and the outer diameter of the first spacing element, so that the aberration of a system is balanced, the contact width between the image side surface and the object side surface of the first spacing element and the lens can limit the part of the lens mechanism to reflect to generate redundant light, the assembly deformation of the first lens can be optimized and the second lens can better lean forwards and backwards when the condition formula range is met, the assembly yield of the whole imaging system is improved, and the manufacturing cost is effectively reduced.

In an exemplary embodiment, with reference to the dimensioning of fig. 1, the inner diameter D1s of the object-side face of the first spacer element, the outer diameter D1s of the object-side face of the first spacer element, the inner diameter D1m of the image-side face of the first spacer element, the outer diameter D1m of the image-side face of the first spacer element, the radius of curvature R2 of the image-side face of the first lens and the radius of curvature R3 of the object-side face of the second lens are satisfied: l (R2 + D1 s)/(R3 + D1 m) | <4. By controlling the curvature of the image side surface of the first lens and the curvature of the object side surface of the second lens to be matched with the inner diameter and the outer diameter of the first spacing element, a stray light path generated by the inter-object reflection of the image side surface of the first lens and the object side surface of the second lens can be shielded, the examination requirement is met by the relative-contrast outer field of view, and meanwhile, the imaging quality of the imaging system can be improved.

In an exemplary embodiment, the plurality of spacer elements further comprises a third spacer element positioned between the second lens piece and the third lens piece, wherein the object side surface of the third spacer element is in contact with at least a portion of the image side surface of the second lens piece and the image side surface of the third spacer element is in contact with at least a portion of the object side surface of the third lens piece; and the imaging system satisfies: 25< (d 2s + d3 s)/(R3 + R4) × V2<60, reference is made to the dimensioning of fig. 1, where d2s is the inner diameter of the object-side face of the second spacing element, d3s is the inner diameter of the object-side face of the third spacing element, R3 is the radius of curvature of the object-side face of the second optic, R4 is the radius of curvature of the image-side face of the second optic, and V2 is the abbe number of the second optic. The curvature of the object side surface and the image side surface of the second lens is controlled to be matched with the inner diameter of the object side surface of the second spacing element and the inner diameter of the object side surface of the third spacing element, the light path range of the second lens which is emitted and incident into the third lens can be reasonably limited, light with poor edge quality can be eliminated, the stability of the second lens and the third lens in bearing and leaning can be effectively improved, the sensitivity of the assembling structure between the lenses is reduced, and the imaging quality of an imaging system is improved.

In an exemplary embodiment, the plurality of spacer elements further comprises a third spacer element positioned between the second lens plate and the third lens plate, wherein the object-side surface of the third spacer element is in contact with at least a portion of the image-side surface of the second lens plate and the image-side surface of the third spacer element is in contact with at least a portion of the object-side surface of the third lens plate; and the imaging system satisfies: 1< -D3s tan (Semi-FOV)/T23 <5, with reference to the dimensional designations of FIG. 1, wherein D3s is the outer diameter of the object-side face of the third spacing element, the Semi-FOV is half the maximum field angle of the lens set and T23 is the distance on the optical axis between the second and third lenses. By controlling the conditions, the light path of the second lens mechanism part can be limited from being emitted, a stray light path generated by the lens mechanism part is shielded, and the incidence of an effective light path is improved to ensure the relative illumination of an outer view field; with the control of clearance ratio, can promote the structural stability of second lens and third lens assemblage, reduce the clearance field curvature sensitivity around second lens and the third lens, promote imaging system's formation of image quality.

In an exemplary embodiment, the plurality of spacing elements includes a third spacing element between the second lens and the third lens, a fourth spacing element between the third lens and the fourth lens, and a fifth spacing element between the fourth lens and the fifth lens, and with reference to the dimensional indicia of fig. 1, the imaging system satisfies: EP23/CT2<1.5 and 1 are woven into EP34/CT3<3 and EP45/CT4<1.5, where EP23 is the distance of the second spacer element from the third spacer element on the optical axis, CT2 is the central thickness of the second lens on the optical axis, EP34 is the distance of the third spacer element from the fourth spacer element on the optical axis, CT3 is the central thickness of the third lens on the optical axis, EP45 is the distance of the fourth spacer element from the fifth spacer element on the optical axis, and CT4 is the central thickness of the fourth lens on the optical axis. By controlling the condition, the distance between any two adjacent spacing elements in the second spacing element to the fifth spacing element can be adjusted to adjust the distance between each lens in the first lens to the fifth lens, so that the sensitivity of field curvature can be reduced, the thickness control of the lens is improved, and the formability of the lens is improved; in addition, the distance between the lens and the adjacent lens is adjusted by further controlling the center thickness of each lens from the second lens to the fourth lens, so that the stability of the imaging system can be ensured, and a good imaging effect can be obtained. And, by controlling the distance between the above-mentioned spacing elements and the center thickness of each of the second lens to the fourth lens, the imaging system is further miniaturized and ultra-thinned.

In an exemplary embodiment, with reference to the dimensioning of fig. 1, the distance EP45 of the fourth spacer element from the fifth spacer element on the optical axis, the thickness CP4 of the fourth spacer element, the central thickness CT4 of the fourth lens on the optical axis and the refractive index N4 of the fourth lens are satisfied: 1< (EP 45+ CP 4)/CT 4N 4<5. The central thickness of the fourth lens is controlled to optimize the shape of the fourth lens so as to ensure the machinability of the lens, thereby improving the material forming stability of the fourth lens and reducing the stress influence generated by assembly in the assembly process so as to obtain good assembly yield.

In an exemplary embodiment, with reference to the dimensioning of fig. 1, the distance EP34 of the third spacer element from the fourth spacer element on the optical axis, the thickness CP4 of the fourth spacer element, the central thickness CT3 of the third lens on the optical axis and the distance T23 of the second lens from the third lens on the optical axis satisfy: 0< (EP 34+ CP 4)/(CT 3+ T23) <2. By controlling the condition, the structural stability of the fifth lens can be enhanced, the gathering stress conduction in the assembling process is uniform, and the variation of the central stress of the second lens and the third lens is reduced. The distribution positions of the second lens and the third lens in the optical system can be reasonably distributed, the sensitivity of the front and back clearance field curvature of the second lens and the third lens is reduced, and the optical system can obtain good imaging effect.

In an exemplary embodiment, the first lens is made of glass, and any one of the second lens to the fifth lens is made of plastic. The first lens is made of glass materials, so that the first lens has higher Abbe number and higher refractive index, and the size of the optical lens group can be reduced; any one of the second lens to the fifth lens is made of plastic materials, so that the cost of the lens group is saved, the cost of the imaging lens is reduced, and the processing difficulty of the lenses is reduced while high imaging quality is obtained. In an exemplary embodiment, the lens group according to the present application may further include a filter for correcting color deviation and/or a protective glass for protecting a photosensitive element located on an image plane.

The lens set according to the above embodiments of the present application may employ a plurality of lenses, such as the above five lenses. By reasonably distributing the refractive power, the surface type, the center thickness of each lens, the on-axis distance between lenses and the like of each lens, the low-order aberration of the imaging system can be effectively balanced and controlled, meanwhile, the tolerance sensitivity can be reduced, and the miniaturization of the imaging system can be kept.

In an embodiment of the present application, at least one of the mirror surfaces of each of the first to fifth lenses is an aspherical mirror surface. The aspheric lens is characterized in that: the curvature varies continuously from the center of the lens to the periphery of the lens. Unlike a spherical lens having a constant curvature from the lens center to the lens periphery, an aspherical lens has a better curvature radius characteristic, and has advantages of improving distortion aberration and improving astigmatic aberration. After the aspheric lens is adopted, the aberration generated in imaging can be eliminated as much as possible, and the imaging quality is further improved. Optionally, the object-side surface and the image-side surface of each of the first lens to the fifth lens are aspheric mirror surfaces.

However, it will be appreciated by those skilled in the art that the number of lenses making up the imaging system can be varied to achieve the various results and advantages described in this specification without departing from the claimed technology. For example, although the embodiment has been described with five lenses as an example, the imaging system is not limited to include five lenses. The imaging system may also include other numbers of lenses, if desired.

Specific examples of imaging systems that can be adapted to the above-described embodiments are further described below with reference to the accompanying drawings.

Example 1

The lens group and the imaging system according to embodiment 1 of the present application are described below with reference to fig. 2 to 6C. Fig. 1 shows a schematic structural diagram of a lens set according to embodiment 1 of the present application. Fig. 3 to 5 respectively show cross-sectional schematic views of three imaging systems including the lens group shown in fig. 2 according to embodiment 1 of the present application.

As shown in fig. 2, the lens assembly includes, in order from an object side to an image side: a first lens E1, a stop STO, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a filter E6, and an image plane S13.

The first lens element E1 with positive refractive power has a convex object-side surface S1 and a convex image-side surface S2. The second lens element E2 with positive refractive power has a convex object-side surface S3 and a concave image-side surface S4. The third lens element E3 with negative refractive power has a concave object-side surface S5 and a concave image-side surface S6. The fourth lens element E4 with positive refractive power has a convex object-side surface S7 and a concave image-side surface S8. The fifth lens element E5 with positive refractive power has a concave object-side surface S9 and a convex image-side surface S10. The filter E6 has an object side surface S11 and an image side surface S12. The light from the object passes through the respective surfaces S1 to S12 in order and is finally imaged on the imaging plane S13.

Table 1 shows a basic parameter table for the lens set of example 1, wherein the radius of curvature, thickness/distance and focal length are all in millimeters (mm).

TABLE 1

In this embodiment, the total effective focal length f of the lens assembly is 19.13mm, the distance TTL between the object-side surface S1 of the first lens element E1 and the image plane S13 is 19.13mm, the half ImgH of the diagonal length of the effective pixel area on the image plane S13 is 3.47mm, the aperture value Fno of the lens assembly is 3.47, and the half Semi-FOV of the maximum field angle of the lens assembly is 9.94 °.

In the present embodiment, the aspheric surface type x included in the object-side surface and the image-side surface of the lenses of the first lens E1 to the fifth lens E5 can be defined by, but is not limited to, the following aspheric surface 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 =1/R (i.e., paraxial curvature c is the inverse of radius of curvature R in table 1 above); k is a conic coefficient; ai is the correction coefficient of the i-th order of the aspherical surface. Table 2 below gives the coefficients A4, A6, A8, a10, and a11 of high-order terms that can be used for the aspherical mirrors S7 and S8 in example 1.

Flour mark	A4	A6	A8	A10	A11
						S7	-1.9322E-03	-2.3392E-04	-4.2181E-05	8.1749E-06	-9.4232E-07
S8	-1.1810E-03	-3.4930E-04	1.4113E-05	-4.7625E-06	3.3447E-07

TABLE 2

As shown in fig. 3, the imaging system 110 includes the lens group, a lens barrel 111 for accommodating the lens group, and a plurality of spacing elements P1 to P5 located between any two adjacent lenses of the plurality of lenses. As shown in fig. 4, the imaging system 120 includes the lens group, a lens barrel 121 for accommodating the lens group, and a plurality of spacing elements P1 to P5 located between any two adjacent lenses of the plurality of lenses. As shown in fig. 5, the imaging system 130 includes the lens group, a lens barrel 131 for accommodating the lens group, and a plurality of spacing elements P1 to P5 located between any two adjacent lenses of the plurality of lenses. In the imaging system as shown in fig. 3 to 5, the first and second spacing elements P1 and P2 are located between the first and second lenses E1 and E2, and the first spacing element P1 is in contact with at least a portion of the image side surface S2 portion of the first lens E1, and the second spacing element P2 is in contact with at least a portion of the object side surface S3 portion of the second lens E2. A third spacing element P3 is located between the second lens E2 and the third lens E3, a fourth spacing element P4 is located between the third lens E3 and the fourth lens E4, and a fifth spacing element P5 is located between the fourth lens E5 and the fifth lens E5. In the present embodiment, the first P1 and fourth P4 spacing elements are spacers and the second P2, third P3 and fifth P5 spacing elements are spacers. The first to fifth spacing elements P1 to P5 can block the entry of external unwanted light, make the lens and the lens barrel better bear, and enhance the structural stability of the imaging system.

Table 3 shows a basic parameter table of the lens barrel and the spacer element of the three imaging systems of embodiment 1, and the unit of each parameter in table 3 is millimeter (mm).

System numbering	d1s	d1m	D1s	D1m	d2s	D2s	d3s	D3s	EP23	EP34	EP45	d0m	d0s	CP4
															110	5.38	5.00	5.91	5.49	4.58	6.1	3.92	6.00	0.98	1.39	0.53	4.36	7.60	0.89
120	5.28	4.90	6.13	5.69	4.48	6.3	3.82	6.20	0.98	1.39	0.53	4.36	7.60	0.89
															130	5.18	4.70	6.43	5.99	4.38	6.6	3.64	6.50	0.98	1.39	0.53	4.36	7.60	0.89

TABLE 3

Fig. 6A shows an astigmatism curve representing a meridional field curvature and a sagittal field curvature of the imaging system of embodiment 1. Fig. 6B shows a distortion curve of the imaging system of embodiment 1, which represents distortion magnitude values corresponding to different image heights. Fig. 6C shows a chromatic aberration of magnification curve of the imaging system of embodiment 1, which represents the deviation of different image heights on the imaging plane after the light passes through the imaging system. As can be seen from fig. 6A to 6C, the imaging system according to embodiment 1 can achieve good imaging quality.

Example 2

A lens group and an imaging system according to embodiment 2 of the present application are described below with reference to fig. 7 to 11C. Fig. 7 is a schematic structural diagram of a lens group according to embodiment 2 of the present application. Figures 8-10 show cross-sectional schematic views of three imaging systems including the set of lenses shown in figure 7, respectively, according to example 2 of the present application.

As shown in fig. 7, the lens assembly, in order from an object side to an image side along an optical axis, comprises: a first lens E1, a stop STO, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a filter E6, and an image plane S13.

The first lens element E1 with positive refractive power has a convex object-side surface S1 and a concave image-side surface S2. The second lens element E2 with negative refractive power has a convex object-side surface S3 and a concave image-side surface S4. The third lens element E3 with negative refractive power has a concave object-side surface S5 and a concave image-side surface S6. The fourth lens element E4 with positive refractive power has a convex object-side surface S7 and a concave image-side surface S8. The fifth lens element E5 with positive refractive power has a concave object-side surface S9 and a convex image-side surface S10. The filter E6 has an object side surface S11 and an image side surface S12. The light from the object sequentially passes through the respective surfaces S1 to S12 and is finally imaged on the imaging surface S13.

Table 4 shows a basic parameter table for the lens set of example 2, wherein the radius of curvature, thickness/distance, and focal length are all in millimeters (mm).

TABLE 4

In this embodiment, the total effective focal length f of the lens assembly is 17.50mm, the distance TTL between the object-side surface S1 of the first lens element E1 and the image plane S13 on the optical axis is 19.00mm, the half ImgH of the diagonal length of the effective pixel area on the image plane S13 is 3.67mm, the aperture value Fno of the lens assembly is 3.53, and the half Semi-FOV of the maximum field angle of the lens assembly is 11.80 °.

Tables 5 and 6 show high-order term coefficients A4, A6, A8, a10, a11, a12, a13, a14, a15, a16, a17, a18, and a19 of respective mirror surfaces usable for the aspherical surfaces S1 to S10 in example 2, wherein the respective aspherical surface types can be defined by the formula (1) given in example 1 above.

Flour mark

A4

A6

A8

A10

A11

A12

A13

S1

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

S2

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

S3

-1.2509E-04

7.1678E-04

-5.1620E-04

9.8696E-05

6.0653E-05

-4.4978E-05

1.2808E-05

S4

-3.9926E-03

1.1612E-02

-1.0570E-02

3.5170E-03

1.4184E-03

-1.9903E-03

9.5327E-04

S5

-2.7159E-02

8.3560E-02

-1.1627E-01

9.9887E-02

-5.6527E-02

2.1425E-02

-5.2532E-03

S6

-4.6769E-02

1.2046E-01

-1.6120E-01

1.3576E-01

-7.5099E-02

2.7788E-02

-6.7281E-03

S7

-3.4242E-02

4.6192E-02

-2.3956E-02

-3.7055E-02

1.0070E-01

-1.2576E-01

1.0317E-01

S8

-2.1323E-02

4.8760E-03

6.5270E-02

-1.8755E-01

2.8997E-01

-2.9862E-01

2.1615E-01

S9

-7.2155E-03

-9.8585E-03

5.6360E-02

-1.1660E-01

1.4580E-01

-1.2273E-01

7.2027E-02

S10

-8.1114E-04

-9.8461E-03

2.9761E-02

-5.1478E-02

5.8862E-02

-4.6500E-02

2.5836E-02

TABLE 5

Flour mark

A14

A15

A16

A17

A18

A19

S1

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

S2

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

S3

-1.7959E-06

1.0246E-07

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

S4

-2.3359E-04

2.4070E-05

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

S5

7.4792E-04

-4.6151E-05

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

S6

9.7315E-04

-6.3968E-05

0.0000E+00

0.0000E+00

0.0000E+00

0.0000E+00

S7

-5.9126E-02

2.3774E-02

-6.5638E-03

1.1834E-03

-1.2532E-04

5.9041E-06

S8

-1.1138E-01

4.0580E-02

-1.0202E-02

1.6817E-03

-1.6340E-04

7.0871E-06

S9

-2.9570E-02

8.3237E-03

-1.5300E-03

1.6534E-04

-7.9638E-06

0.0000E+00

S10

-1.0069E-02

2.6923E-03

-4.6995E-04

4.8190E-05

-2.2001E-06

0.0000E+00

TABLE 6

As shown in fig. 8, the imaging system 210 includes the lens group, a lens barrel 211 for accommodating the lens group, and a plurality of spacing elements P1 to P5 located between any two adjacent lenses of the plurality of lenses. As shown in fig. 9, the imaging system 220 includes the lens group, a lens barrel 221 for accommodating the lens group, and a plurality of spacing elements P1 to P5 located between any two adjacent lenses of the plurality of lenses. As shown in fig. 10, the imaging system 230 includes the lens group, a lens barrel 231 for accommodating the lens group, and a plurality of spacing elements P1 to P5 located between any two adjacent lenses of the plurality of lenses. In the imaging system as shown in fig. 8 to 10, the first and second spacing elements P1 and P2 are located between the first and second lenses E1 and E2, and the first spacing element P1 is in contact with at least a portion of the image side surface S2 of the first lens E1, and the second spacing element P2 is in contact with at least a portion of the object side surface S3 of the second lens E2. The third spacing element P3 is located between the second lens E2 and the third lens E3, the fourth spacing element P4 is located between the third lens E3 and the fourth lens E4, and the fifth spacing element P5 is located between the fourth lens E5 and the fifth lens E5. In the present embodiment, the first P1 and fourth P4 spacer elements are spacers and the second P2, third P3 and fifth P5 spacer elements are spacers. The first to fifth spacing elements P1 to P5 can block the entry of external unwanted light, make the lens and the lens barrel better bear, and enhance the structural stability of the imaging system.

Table 7 shows a basic parameter table of the lens barrel and the spacer of three imaging systems of embodiment 2, and the unit of each parameter in table 7 is millimeter (mm).

System numbering	d1s	d1m	D1s	D1m	d2s	D2s	d3s	D3s	EP23	EP34	EP45	d0m	d0s	CP4
															210	5.01	4.83	5.83	5.92	4.22	6.1	3.27	5.8	1.45	1	0.75	3.61	7.56	0.48
220	4.91	4.73	6.03	6.12	4.12	6.3	3.17	6	1.45	1	0.75	3.6	7.56	0.48
															230	4.71	4.63	6.23	6.32	3.92	6.5	2.97	6.2	1.45	1	0.75	3.6	7.56	0.48

TABLE 7

Fig. 11A shows an astigmatism curve representing meridional field curvature and sagittal field curvature of the imaging system of embodiment 2. Fig. 11B shows a distortion curve of the imaging system of embodiment 2, which represents distortion magnitude values corresponding to different image heights. Fig. 11C shows a chromatic aberration of magnification curve of the imaging system of embodiment 2, which represents the deviation of different image heights on the imaging plane after the light passes through the imaging system. As can be seen from fig. 11A to 11C, the imaging system according to embodiment 2 can achieve good imaging quality.

Example 3

A lens group and an imaging system according to embodiment 3 of the present application are described below with reference to fig. 12 to 16C. Figure 12 shows a schematic view of a structure of a lens set according to embodiment 3 of the present application. Figures 13-15 respectively show cross-sectional schematic views of three imaging systems including the lens stack shown in figure 12 according to embodiment 3 of the present application.

As shown in fig. 12, the lens assembly, in order from an object side to an image side along an optical axis, comprises: a first lens E1, a stop STO, a second lens E2, a third lens E3, a fourth lens E4, a fifth lens E5, a filter E6 and an image plane S13.

The first lens element E1 with positive refractive power has a convex object-side surface S1 and a convex image-side surface S2. The second lens element E2 with positive refractive power has a convex object-side surface S3 and a concave image-side surface S4. The third lens element E3 with negative refractive power has a concave object-side surface S5 and a concave image-side surface S6. The fourth lens element E4 with positive refractive power has a convex object-side surface S7 and a convex image-side surface S8. The fifth lens element E5 with positive refractive power has a concave object-side surface S9 and a convex image-side surface S10. The filter E6 has an object side surface S11 and an image side surface S12. The light from the object passes through the respective surfaces S1 to S12 in order and is finally imaged on the imaging plane S13.

Table 8 shows a table of basic parameters for the lens set of example 3, wherein the radii of curvature, thickness/distance, and focal length are all in millimeters (mm).

TABLE 8

In this embodiment, the total effective focal length f of the lens assembly is 19.36mm, the axial distance TTL between the object-side surface S1 of the first lens element E1 and the image plane S13 is 19.26mm, a half ImgH of a diagonal length of the effective pixel area on the image plane S13 is 3.47mm, the aperture Fno of the lens assembly is 3.47, and a half Semi-FOV of a maximum field angle of the lens assembly is 9.86 °.

Table 9 shows the high-order term coefficients A4, A6, A8, a10, a11, and a12 of the respective mirror surfaces usable for the aspherical surfaces S7 to S10 in example 3, wherein the respective aspherical surface types can be defined by the formula (1) given in example 1 above.

Flour mark

A4

A6

A8

A10

A11

A12

S7

-8.7238E-04

-6.3695E-04

2.6713E-04

-2.4668E-05

0.0000E+00

0.0000E+00

S8

6.0455E-04

-5.3345E-04

1.9482E-04

7.7895E-06

-5.3821E-06

2.5748E-07

S9

5.7688E-04

-1.6141E-04

2.7833E-06

-2.1491E-06

-1.6595E-06

0.0000E+00

S10

4.9443E-05

7.7557E-06

-2.8035E-05

-3.1061E-06

1.1323E-07

0.0000E+00

TABLE 9

As shown in fig. 13, the imaging system 310 includes the lens group, a lens barrel 311 for accommodating the lens group, and a plurality of spacing elements P1 to P5 located between any two adjacent lenses of the plurality of lenses. As shown in fig. 14, the imaging system 320 includes the lens group, a lens barrel 321 for accommodating the lens group, and a plurality of spacing elements P1 to P5 located between any two adjacent lenses of the plurality of lenses. As shown in FIG. 15, the imaging system 330 includes the lens group, a lens barrel 331 for accommodating the lens group, and a plurality of spacing elements P1-P5 located between any two adjacent lenses of the plurality of lenses. In the imaging system as shown in fig. 13-15, the first and second spacing elements P1 and P2 are located between the first and second lenses E1 and E2, and the first spacing element P1 is in contact with at least a portion of the image side surface S2 of the first lens E1 and the second spacing element P2 is in contact with at least a portion of the object side surface S3 of the second lens E2. A third spacing element P3 is located between the second lens E2 and the third lens E3, a fourth spacing element P4 is located between the third lens E3 and the fourth lens E4, and a fifth spacing element P5 is located between the fourth lens E5 and the fifth lens E5. In the present embodiment, the first spacing element P1 is a spacer, and the second to fifth spacing elements P2 to P5 are spacers. The first to fifth spacing elements P1 to P5 can block the entry of external unwanted light, make the lens and the lens barrel better bear, and enhance the structural stability of the imaging system.

Table 10 shows a basic parameter table of the lens barrel and the spacer element of the three imaging systems of embodiment 3, and the unit of each parameter in table 10 is millimeter (mm).

Watch 10

Fig. 16A shows an astigmatism curve representing meridional field curvature and sagittal field curvature of the imaging system of embodiment 3. Fig. 16B shows a distortion curve of the imaging system of embodiment 3, which represents distortion magnitude values corresponding to different image heights. Fig. 16C shows a chromatic aberration of magnification curve of the imaging system of embodiment 3, which represents the deviation of different image heights on the imaging plane after the light passes through the imaging system. As can be seen from fig. 16A to 16C, the imaging system according to embodiment 3 can achieve good imaging quality.

In summary, examples 1 to 3 satisfy the relationships shown in table 11, respectively.

TABLE 11

The above description is only a preferred embodiment of the application and is illustrative of the principles of the technology employed. It will be appreciated by a person skilled in the art that the scope of protection covered by the present application is not limited to the embodiments with a specific combination of the features described above, but also covers other embodiments with any combination of the features described above or their equivalents without departing from the scope of the present application. For example, the above features may be replaced with (but not limited to) features having similar functions disclosed in the present application.

Claims (11)

1. The imaging system comprises a lens group and a plurality of spacing elements, wherein the lens group sequentially comprises from an object side to an image side along an optical axis:

a first lens having positive refractive power;

the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface;

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

a fourth lens element with positive refractive power;

a fifth lens, the object side surface of which is a concave surface and the image side surface of which is a convex surface; wherein the plurality of spacer elements comprises at least one spacer element located between any two adjacent lenses, wherein the at least one spacer element is in contact with at least a portion of a lens located on an object side thereof, and the at least one spacer element located between the first lens and the second lens comprises a first spacer element and a second spacer element, and the imaging system satisfies:

2<(D2s-d2s)/(D1s-d1s)+(f1*tan(Semi-FOV))<10，

wherein D1s is an inner diameter of an object-side surface of the first spacer element, D1s is an outer diameter of an object-side surface of the first spacer element, D2s is an inner diameter of an object-side surface of the second spacer element, D2s is an outer diameter of an object-side surface of the second spacer element, f1 is an effective focal length of the first lens, and Semi-FOV is half of a maximum field angle of the lens group.

2. The imaging system of claim 1, wherein an inner diameter D1s of the object-side surface of the first spacer element, an outer diameter D1s of the object-side surface of the first spacer element, an inner diameter D1m of the image-side surface of the first spacer element, an outer diameter D1m of the image-side surface of the first spacer element, a radius of curvature R2 of the image-side surface of the first lens, and a radius of curvature R3 of the object-side surface of the second lens satisfy: l (R2/R3) + (D1 s/D1 m) + (D1 s/D1 m) | <20.

3. The imaging system of claim 1, wherein an inner diameter D1s of the object-side surface of the first spacer element, an outer diameter D1s of the object-side surface of the first spacer element, an inner diameter D1m of the image-side surface of the first spacer element, an outer diameter D1m of the image-side surface of the first spacer element, a radius of curvature R2 of the image-side surface of the first lens, and a radius of curvature R3 of the object-side surface of the second lens satisfy: l (R2 + D1 s)/(R3 + D1 m) | <4.

4. The imaging system of claim 1, wherein the plurality of spacer elements further comprises a third spacer element positioned between the second lens piece and the third lens piece, wherein an object-side surface of the third spacer element is in contact with at least a portion of an image-side surface of the second lens piece and an image-side surface of the third spacer element is in contact with at least a portion of an object-side surface of the third lens piece; and the imaging system satisfies:

25<(d2s+d3s)/(R3+R4)*V2<60，

wherein d2s is an inner diameter of an object-side surface of the second spacer element, d3s is an inner diameter of an object-side surface of the third spacer element, R3 is a radius of curvature of an object-side surface of the second lens, R4 is a radius of curvature of an image-side surface of the second lens, and V2 is an abbe number of the second lens.

5. The imaging system of claim 1, wherein the plurality of spacer elements further comprises a third spacer element positioned between the second lens plate and the third lens plate, wherein an object-side surface of the third spacer element is in contact with at least a portion of an image-side surface of the second lens plate and an image-side surface of the third spacer element is in contact with at least a portion of an object-side surface of the third lens plate; and the imaging system satisfies:

1<D3s*tan(Semi-FOV)/T23<5，

wherein D3s is an outer diameter of an object-side surface of the third spacer element, the Semi-FOV is a half of a maximum field angle of the lens group, and T23 is a distance between the second lens and the third lens on the optical axis.

6. The imaging system of claim 1, wherein the plurality of spacer elements further comprises a third spacer element positioned between the second lens and the third lens, wherein a distance EP23 of the second spacer element from the third spacer element on the optical axis satisfies a central thickness CT2 of the second lens on the optical axis: 0< -EP23/CT 2<3.

7. The imaging system of claim 6, wherein the plurality of spacing elements further comprises a fourth spacing element between the third lens and the fourth lens, wherein a distance EP34 of the third spacing element from the fourth spacing element on the optical axis satisfies between a center thickness CT3 of the third lens on the optical axis: 0-straw EP34/CT3<3.

8. The imaging system of claim 7, wherein the plurality of spacer elements further comprises a fifth spacer element positioned between the fourth lens and the fifth lens, wherein a distance EP45 of the fourth spacer element from the fifth spacer element on the optical axis satisfies a central thickness CT4 of the fourth lens on the optical axis: 0< -EP45/CT 4<3.

9. The imaging system of claim 1, wherein the plurality of spacer elements further comprises a fourth spacer element between the third and fourth lenses and a fifth spacer element between the fourth and fifth lenses, wherein a distance EP45 of the fourth and fifth spacer elements on the optical axis, a thickness CP4 of the fourth spacer element, a center thickness CT4 of the fourth lens on the optical axis, and a refractive index N4 of the fourth lens satisfy: 1< (EP 45+ CP 4)/CT 4 × N4<5.

10. The imaging system of claim 7, wherein a distance EP34 of the third and fourth spacing elements on the optical axis, a thickness CP4 of the fourth spacing element, a center thickness CT3 of the third lens on the optical axis, and a distance T23 of the second and third lenses on the optical axis satisfy: 0< (EP 34+ CP 4)/(CT 3+ T23) <2.

11. The imaging system of claim 1, wherein the first lens is made of glass, and any one of the second lens to the fifth lens is made of plastic.

Images