Imaging system

Abstract

The application discloses an imaging system, which comprises, in sequence from the object side to the image side along the optical axis, a first lens with positive refractive power, a first spacer element in contact with the image side surface of the first lens, a second lens with negative refractive power, a second spacer element in contact with the image side surface of the second lens, a third lens with positive refractive power, a third spacer element in contact with the image side surface of the third lens, a fourth lens with positive refractive power, the object side surface of which is a convex surface, a fourth spacer element in contact with the image side surface of the fourth lens, a fifth lens with negative refractive power, the image side surface of which is a convex surface, a fifth spacer element in contact with the image side surface of the fifth lens, and a sixth lens with negative refractive power, wherein at least one lens among the first lens to the sixth lens is an aspherical lens, the radius of curvature R2 of the image side surface of the first lens, the radius of curvature R12 of the image side surface of the sixth lens, the outer diameter D2m of the image side surface of the second spacer element, and the outer diameter D5m of the image side surface of the fifth spacer element satisfy the following condition: -13.0 < (R2 / D2m) + (R12 / D5m) < 13.0.

Description

Technical Field

[0001] This application relates to the field of optical components, and more specifically, to an imaging system. Background Technology

[0002] With the improvement in performance and reduction in size of charge-coupled device (CCD) and complementary metal-oxide semiconductor (CMOS) image sensors, the corresponding imaging systems also need to meet the requirements of high imaging quality and miniaturization. At the same time, the emerging dual-camera technology generally requires the use of telephoto lenses to obtain high spatial angular resolution. The stray light index and automatic assembly stability of the imaging system play a crucial role in the image quality.

[0003] In other words, the existing six-element optical imaging system cannot simultaneously meet the design requirements of telephoto lenses while also taking into account stray light and assembly stability. Summary of the Invention

[0004] This application provides an imaging system comprising, along the optical axis from the object side to the image side, the following components in sequence: a first lens having positive optical power; a first spacer element contacting the image-side surface of the first lens; a second lens having negative optical power; a second spacer element contacting the image-side surface of the second lens; a third lens having positive optical power; a third spacer element contacting the image-side surface of the third lens; a fourth lens having positive optical power, its object side surface being convex; a fourth spacer element contacting the image-side surface of the fourth lens; and a fifth lens having negative optical power. The image-side surface of the first lens is convex; the fifth spacer element is in contact with the image-side surface of the fifth lens; the sixth lens has negative optical power; wherein, at least one of the first to sixth lenses is an aspherical lens, and the radius of curvature R2 of the image-side surface of the first lens, the radius of curvature R12 of the image-side surface of the sixth lens, the outer diameter D2m of the image-side surface of the second spacer element, and the outer diameter D5m of the image-side surface of the fifth spacer element satisfy the following: -13.0 < (R2 / D2m) + (R12 / D5m) < 13.0.

[0005] In one embodiment of this application, the effective focal length f1 of the first lens, the effective focal length f5 of the fifth lens, the thickness CP1 of the first spacer element, and the thickness CP5 of the fifth spacer element satisfy the following: -230 < f5 / CP5 + f1 / CP1 < -18.0.

[0006] In one embodiment of this application, the distance EP34 between the third spacer element and the fourth spacer element on the optical axis, the distance EP45 between the fourth spacer element and the fifth spacer element on the optical axis, the center thickness CT3 of the third lens on the optical axis, and the center thickness CT4 of the fourth lens on the optical axis satisfy the following: -7.0 < (EP34 + EP45) / (CT3 - CT4) < -3.0.

[0007] In one embodiment of this application, the radius of curvature R8 of the image side of the fourth lens, the inner diameter d2m of the image side of the second spacer element, and the inner diameter d3m of the image side of the third spacer element satisfy the following: 4.0 < |R8 / (d3m+d2m)| < 9.0.

[0008] In one embodiment of this application, the thickness CP3 of the third spacer element, the distance EP23 between the second spacer element and the third spacer element on the optical axis, the distance T23 between the second lens and the third lens on the optical axis, and the center thickness CT3 of the third lens on the optical axis satisfy the following: 1.5 < T23 / CP3 + EP23 / CT3 < 61.0.

[0009] In one embodiment of this application, the distance T45 between the fourth lens and the fifth lens on the optical axis, the outer diameter D4s of the object side of the fourth spacer element, the inner diameter d4s of the object side of the fourth spacer element, and the thickness CP4 of the fourth spacer element satisfy the following: 7.0 < (D4s + d4s) / (CP4 + T45) < 16.0.

[0010] In one embodiment of this application, the radius of curvature R5 of the object side of the third lens, the sum of the distances ∑AT between any two adjacent lenses from the first lens to the sixth lens on the optical axis, and the sum of the distances ∑EP between any two adjacent spacers from the first spacer element to the fifth spacer element on the optical axis satisfy: 24.0 < |R5 / (∑EP-∑AT)| < 45.0.

[0011] In one embodiment of this application, the sum of the thicknesses of each of the first to the fifth spacer elements, ∑CP, the radius of curvature R11 of the object side surface of the sixth lens, and the sum of the center thicknesses of each of the first to the sixth lenses on the optical axis, ∑CT, satisfy: 0 < |R11 / (∑CP + ∑CT)| < 13.0.

[0012] In one embodiment of this application, the effective focal length f3 of the third lens, the effective focal length f5 of the fifth lens, the center thickness CT3 of the third lens on the optical axis, the center thickness CT5 of the fifth lens on the optical axis, the thickness CP3 of the third spacer element, the thickness CP5 of the fifth spacer element, the outer diameter D5s of the object side of the fifth spacer element, and the inner diameter d5m of the image side of the fifth spacer element satisfy the following: -24.0 ≤ (f5 CP3 CT5 CT3-f3 CP5 CT5 CT3) / (CP3 CP5 D5s d5m) < -10.0.

[0013] In one embodiment of this application, a lens barrel is used to accommodate each lens and each spacer element, wherein the dimension L of the lens barrel along the optical axis, the radius of curvature R2 of the image side surface of the first lens, and the radius of curvature R12 of the image side surface of the sixth lens satisfy the following: -15.0≤(R2-R12) / L<7.0.

[0014] The imaging system of this application includes a lens barrel, multiple lenses, and multiple spacer elements. By placing spacer elements between adjacent lenses, excess light can be effectively blocked, thereby improving stray light. Furthermore, the bearing arrangement between the lenses and spacer elements improves the stability and consistency during lens assembly, avoiding yield losses during production. In addition, this application uses multiple lenses (e.g., six lenses). By rationally allocating the optical power of each lens and adjusting the relationship between the curvature radius of the image-side surfaces of the first and sixth lenses and the radius of the adjacent spacer elements, the imaging system exhibits excellent bearing stability and improved reliability. Attached Figure Description

[0015] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings:

[0016] Figure 1 A schematic diagram of the spacer element included in the imaging system according to this application for stray light elimination is shown;

[0017] Figure 2 A schematic diagram showing the parameter annotations of the imaging system according to this application is provided;

[0018] Figure 3 A cross-sectional schematic diagram of an imaging system according to Embodiment 1 of this application is shown;

[0019] Figure 4 A cross-sectional schematic diagram of another imaging system according to Embodiment 1 of this application is shown;

[0020] Figure 5 A cross-sectional schematic diagram of another imaging system according to Embodiment 1 of this application is shown;

[0021] Figures 6A to 6D The astigmatism curve, distortion curve, magnification chromatic aberration curve, and on-axis chromatic aberration curve of the imaging system according to Embodiment 1 of this application are shown respectively.

[0022] Figure 7 A cross-sectional schematic diagram of an imaging system according to Embodiment 2 of this application is shown;

[0023] Figure 8 A cross-sectional schematic diagram of another imaging system according to Embodiment 2 of this application is shown;

[0024] Figure 9 A cross-sectional schematic diagram of another imaging system according to Embodiment 2 of this application is shown;

[0025] Figures 10A to 10D The astigmatism curve, distortion curve, magnification chromatic aberration curve, and on-axis chromatic aberration curve of the imaging system according to Embodiment 2 of this application are shown respectively.

[0026] Figure 11 A cross-sectional schematic diagram of an imaging system according to Embodiment 3 of this application is shown;

[0027] Figure 12 A cross-sectional schematic diagram of another imaging system according to Embodiment 3 of this application is shown;

[0028] Figure 13 A cross-sectional schematic diagram of another imaging system according to Embodiment 3 of this application is shown;

[0029] Figures 14A to 14D The astigmatism curve, distortion curve, magnification chromatic aberration curve, and on-axis chromatic aberration curve of the imaging system according to Embodiment 3 of this application are shown respectively. Detailed Implementation

[0030] To better understand this application, various aspects of this application will be described in more detail with reference to the accompanying drawings. It should be understood that these detailed descriptions are merely illustrative of exemplary embodiments of this application and are not intended to limit the scope of this application in any way. Throughout the specification, the same reference numerals refer to the same elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0031] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not strictly to scale.

[0032] It should be noted that in this specification, the terms "first," "second," "third," etc., are used only to distinguish one feature from another and do not imply any limitation on the features. Therefore, without departing from the teachings of this application, the first lens discussed below may also be referred to as the second lens or the third lens.

[0033] It should also be understood that the terms "comprising," "including," "having," "containing," and / or "comprising," when used in this specification, indicate the presence of the stated features, elements, and / or components, but do not exclude the presence or addition of one or more other features, elements, components, and / or combinations thereof. Furthermore, when expressions such as "at least one of..." appear after a list of listed features, they modify the entire list of features, not individual elements in the list. Additionally, when describing embodiments of this application, the word "may" is used to mean "one or more embodiments of this application." And the term "exemplary" is intended to refer to an example or illustration.

[0034] Unless otherwise specified, all terms used herein (including technical and scientific terms) shall have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. It should also be understood that terms (e.g., those defined in common dictionaries) shall be interpreted as having the meaning consistent with their meaning in the context of the relevant art and shall not be interpreted in an idealized or overly formal sense, unless expressly so specified herein.

[0035] It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of this application can be combined with each other. The following embodiments only illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the present invention. It should be pointed out that, for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. For example, the structures of the lens group, spacer element, and lens barrel in the various embodiments of this application can be arbitrarily combined, and it is not limited to the lens group in one embodiment being only combined with the structure of the lens barrel, spacer element, etc., of that embodiment. In the accompanying drawings, for ease of explanation, the thickness, size, and shape of the lens have been slightly exaggerated. Specifically, the shapes of spherical or aspherical surfaces shown in the accompanying drawings are shown by way of example. That is, the shapes of spherical or aspherical surfaces are not limited to the shapes of spherical or aspherical surfaces shown in the accompanying drawings. The accompanying drawings are only examples and are not strictly drawn to scale.

[0036] The present application will now be described in detail with reference to the accompanying drawings and embodiments.

[0037] The features, principles and other aspects of this application are described in detail below.

[0038] An imaging system according to an exemplary embodiment of this application may include a lens group, a plurality of spacer elements, and a lens barrel for accommodating the lens group and the spacer elements, wherein the lens group includes, 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, each having an optical power.

[0039] In an exemplary embodiment, the first lens may have positive optical power, its object-side surface may be convex, and its image-side surface may be convex or concave; the second lens may have negative optical power, its object-side surface may be convex, and its image-side surface may be concave, thereby forming a meniscus shape convex towards the object side; the third lens may have positive optical power, its object-side surface may be convex or concave, and its image-side surface may be convex; the fourth lens may have positive optical power, its object-side surface may be convex, and its image-side surface may be convex or concave; the fifth lens may have negative optical power, its object-side surface may be concave, and its image-side surface may be convex, thereby forming a meniscus shape convex towards the image side; the sixth lens may have negative optical power, its object-side surface may be convex or concave, and its image-side surface may be concave. By rationally allocating the surface shape and optical power of each lens in the imaging system, the imaging effect can be effectively improved. Furthermore, by rationally controlling the surface shape of each lens, the resolution of the imaging system can be effectively improved and the aberrations of the imaging system can be balanced by adjusting the path of light in the optical system.

[0040] In an exemplary embodiment, the plurality of spacer elements includes a first spacer element located between a first lens and a second lens, a second spacer element located between a second lens and a third lens, a third spacer element located between a third lens and a fourth lens, a fourth spacer element located between a fourth lens and a fifth lens, and a fifth spacer element located between a fifth lens and a sixth lens. Optionally, the first spacer element contacts the image-side surface of the first lens, the second spacer element contacts the image-side surface of the second lens, the third spacer element contacts the image-side surface of the third lens, the third spacer element contacts the image-side surface of the fourth lens, and the fifth spacer element contacts the image-side surface of the fifth lens. Optionally, in addition to the third spacer element, at least one additional spacer element may be provided between the third lens and the fourth lens. In an example where the at least one additional spacer element is a single spacer element, this single spacer element may contact the third spacer element and may contact the object-side surface of the third lens. In an example where the at least one additional spacer element is two spacer elements, one of the two spacer elements adjacent to the third spacer element contacts the third spacer element and contacts the other spacer element, which may contact the object-side surface of the third lens. By rationally setting multiple spacer elements, it is helpful to intercept excess reflected light paths, improve the imaging clarity of the imaging system, reduce the generation of stray light and ghosting, and ensure the stability of lens components during assembly. For example, when multiple spacer elements are assembled with the lens barrel and lens in sequence, assembly stability can be guaranteed, thereby improving the manufacturing yield of the lens.

[0041] Figure 1 A schematic diagram of the spacer element for eliminating stray light according to this application is shown. It should be understood that the diagram is provided to make the structure and labeling clearer. Figure 1 The example only uses the fourth spacer element P4 to eliminate stray light; the other spacer elements also have the function of eliminating stray light, and the principle of eliminating stray light is the same as that of the fourth spacer element. Figure 1 It is clear that the spacer element 4 can eliminate stray light G generated by multiple reflections of light at the edge of the lens.

[0042] In an exemplary implementation, reference Figure 2For the dimension markings, the following relationships are satisfied among the radius of curvature R2 of the image side of the first lens, the radius of curvature R12 of the image side of the sixth lens, the outer diameter D2m of the image side of the second spacer element, and the outer diameter D5m of the image side of the fifth spacer element: -13.0 < (R2 / D2m) + (R12 / D5m) < 13.0. By reasonably setting the radii of the first lens and the sixth lens, their ratio is within the optimal range. This reduces the abrupt change points of the lens surface shape, reduces the forming difficulty, improves the consistency and stability of lens forming, and increases the assembly yield. At the same time, a reasonable gradient is set between the sixth lens and the first lens to ensure the smooth change of the outer diameters of the remaining lenses, reduce large-step structures, improve the bearing stability of the lens, and enhance the reliability performance. Additionally, by controlling the curvature of the image side of the first lens, it is beneficial to achieve a large field angle of the imaging system, and by controlling the curvature of the image side of the sixth lens, it is beneficial to balance chromatic aberration and control distortion. Meeting the above conditions can make the outer diameter of the image side of the second spacer element match the outer diameter of the image side of the fifth spacer element, and can block the stray light paths generated by the image side reflections of the first lens and the second lens and the stray light paths generated by the image side reflections of the fifth lens and the sixth lens, thereby improving the imaging quality of the imaging system.

[0043] It can be understood that, in order to make the structure and markings of the drawings clearer, Figure 2 only the dimension markings of the structures of individual lenses and individual spacer elements are taken as examples. For the dimension limitations of the similar structures of the remaining lenses and the remaining spacer elements, reference can be made to the relevant dimension structures and markings that have been labeled above, and this application will not elaborate here.

[0044] In an exemplary embodiment, referring to Figure 2 the dimension markings, the following relationships are satisfied among the effective focal length f1 of the first lens, the effective focal length f5 of the fifth lens, the thickness CP1 of the first spacer element, and the thickness CP5 of the fifth spacer element: -230 < f5 / CP5 + f1 / CP1 < -18.0. Further, the above conditional formula can also satisfy: -230.0 < f5 / CP5 + f1 / CP1 < 0 or 0 < f5 / CP5 + f1 / CP1 < -18.0. By reasonably setting the thicknesses of the first spacer element and the fifth spacer element, the internal stress of the lens can be effectively reduced, the deformation amount caused by the release of baking stress can be reduced, thereby reducing the field curvature change of the lens after high temperature and high humidity in reliability, and reducing the problem of barrel deformation caused by the cooperation between the lens and the barrel, and improving the performance yield. By reasonably controlling the focal length of the first lens, it helps to have sufficient converging ability at the object side end to adjust the beam focusing position, thereby shortening the overall length of the system. By reasonably controlling the focal length of the fifth lens, it is beneficial to correct the astigmatism in the sagittal direction and the meridional direction.

[0045] In an exemplary embodiment, referring to Figure 2The dimensions of the third and fourth spacers on the optical axis, specifically the distances EP34 and EP45 between the fourth and fifth spacers, the center thickness CT3 of the third lens, and the center thickness CT4 of the fourth lens on the optical axis, satisfy the following condition: -7.0 < (EP34 + EP45) / (CT3 - CT4) < -3.0. By appropriately setting the ratio of the distance between adjacent spacers in the third, fourth, and fifth spacers to the difference in thickness between the third and fourth lenses, the influence of air gap variations on the lens can be reduced. Furthermore, by further controlling the thickness ratio of the third and fourth lenses, the structural stability of the third and fourth lenses can be enhanced, and field curvature sensitivity can be reduced.

[0046] In an exemplary implementation, reference Figure 2 The dimensions specify that the radius of curvature R8 of the image-side surface of the fourth lens, the inner diameter d2m of the image-side surface of the second spacer element, and the inner diameter d3m of the image-side surface of the third spacer element satisfy the following condition: 4.0 < |R8 / (d3m+d2m)| < 9.0. By controlling the ratio of the radius of curvature of the image-side surface of the fourth lens to the sum of the inner diameters of the image-side surfaces of the second spacer element P2 and the third spacer element P3 within a reasonable range, light leakage can be effectively reduced, high-energy light spots can be prevented, and the image quality of the lens can be improved. Simultaneously, reasonable inner diameters of the second and third spacers improve flatness and reduce tilting during assembly.

[0047] In an exemplary implementation, reference Figure 2 The dimensions of the lens, including the thickness CP3 of the third spacer element, the distance EP23 between the second and third spacers on the optical axis, the distance T23 between the second and third lenses on the optical axis, and the center thickness CT3 of the third lens on the optical axis, satisfy the following condition: 1.5 < T23 / CP3 + EP23 / CT3 < 61.0. By reasonably controlling the ratio of the distance between the second and third lenses to the thickness of the third spacer element, and the ratio of the thickness of the third lens to the distance between the second and third spacers element, the light convergence can be effectively improved, the relative illumination can be increased, and thus the lens imaging performance can be enhanced.

[0048] In an exemplary implementation, reference Figure 2The dimensions of the fourth and fifth lenses, the distance T45 on the optical axis, the outer diameter D4s of the object side of the fourth spacer, the inner diameter d4s of the object side of the fourth spacer, and the thickness CP4 of the fourth spacer satisfy the following: 7.0 < (D4s + d4s) / (CP4 + T45) < 16.0. By reasonably controlling the ratio of the sum of the distance between the fourth and fifth lenses and the thickness of the fourth spacer to the sum of the inner and outer diameters of the object side of the fourth spacer, stray light from circular arcs can be effectively avoided. Simultaneously, the thickness ratio of the fifth lens is improved, resulting in a gentler forming process for the latter two large image-plane lenses and reducing lens outer diameter deformation caused by internal stress.

[0049] In an exemplary implementation, reference Figure 2 The dimensions specify that the radius of curvature R5 of the object-side surface of the third lens, the sum of the distances ∑AT between any two adjacent lenses from the first to the sixth lens on the optical axis, and the sum of the distances ∑EP between any two adjacent spacers from the first to the fifth spacer element on the optical axis satisfy: 24.0 < |R5 / (∑EP-∑AT)| < 45.0. By reasonably controlling the curvature of the object-side surface of the third lens, the smoothness of the third lens can be improved, ghosting in the optical system can be reduced, and the imaging capability of the optical imaging lens can be improved. In addition, by reasonably controlling the difference between the sum of the distances between each lens and the sum of the distances between each spacer element, the product yield loss caused by unstable assembly of each component can be effectively reduced. Furthermore, by controlling the balance of the axial thickness of each spacer element and each lens, stray light problems can be improved, thereby improving image quality.

[0050] In an exemplary implementation, reference Figure 2 The dimensions specify that the sum of the thicknesses of any one of the first to fifth spacers, ∑CP, the radius of curvature R11 of the object-side surface of the sixth lens, and the sum of the center thicknesses of any one of the first to sixth lenses along the optical axis, ∑CT, satisfy: 0 < |R11 / (∑CP + ∑CT)| < 13.0. By reasonably controlling the curvature of the object-side surface of the sixth lens and the relationship between the thicknesses of each lens and each spacer, the risk of weld lines is reduced, while the flatness of the lenses is improved, and tilting during assembly is less likely to occur, thus stabilizing the optical imaging lens.

[0051] In an exemplary implementation, reference Figure 2 The dimensions of the third lens (f3), the fifth lens (f5), the center thickness of the third lens on the optical axis (CT3), the center thickness of the fifth lens on the optical axis (CT5), the thickness of the third spacer (CP3), the thickness of the fifth spacer (CP5), the outer diameter of the object side of the fifth spacer (D5s), and the inner diameter of the image side of the fifth spacer (d5m) satisfy the following: -24.0 ≤ (f5 CP3 CT5 CT3-f3 CP5 CT5 CT3) / (CP3 CP5 D5s (d5m) < -10.0. By reasonably controlling the thickness of the third and fifth spacer elements, the outer diameter of the object side and the inner diameter of the image side, as well as the effective focal length and thickness of the third and fifth lenses, stray light caused by the third and fifth lenses can be avoided. At the same time, controlling the center thickness of the third and fifth lenses is beneficial to improving field curvature stability and overall structural strength, thereby obtaining better reliability performance. Controlling the optical power of the fifth lens is beneficial to achieving telephoto characteristics.

[0052] In an exemplary embodiment, the imaging lens further includes a lens barrel for housing the lenses and spacer elements, see reference. Figure 2 The dimensions are specified, wherein the dimension L of the lens barrel along the optical axis, the radius of curvature R2 of the image-side surface of the first lens, and the radius of curvature R12 of the image-side surface of the sixth lens satisfy the following condition: -15.0 ≤ (R2 - R12) / L < 7.0. Furthermore, the above condition can also satisfy: -15.0 ≤ (R2 - R12) / L < 0 or 0 < (R2 - R12) / L < 7.0. By reasonably setting the curvature of the image-side surfaces of the first and sixth lenses, the risk of convexity of the image-side surface of the first lens and the image plane of the sixth lens can be avoided, reducing lens scratches. Additionally, limiting the axial dimension of the lens barrel allows for miniaturization.

[0053] In an exemplary embodiment, the imaging system according to this application may further include a filter for correcting color deviation and / or a protective glass for protecting the photosensitive element located on the imaging surface.

[0054] The lens group according to the above embodiments of this application can employ multiple lenses, such as the six lenses mentioned above. By rationally allocating the optical power, surface shape, center thickness of each lens, and on-axis spacing between each lens, the low-order aberrations of the imaging system can be effectively balanced and controlled, while reducing its tolerance sensitivity and maintaining the miniaturization of the imaging system.

[0055] In embodiments of this application, at least one of the mirror surfaces of the first to sixth lenses is an aspherical mirror surface. An aspherical lens is characterized by a continuously changing curvature from its center to its periphery. Unlike a spherical lens, which has a constant curvature from its center to its periphery, an aspherical lens has superior curvature radius characteristics, offering advantages in improving distortion and astigmatism. By using an aspherical lens, aberrations occurring during imaging can be eliminated as much as possible, thereby improving image quality. Optionally, both the object-side and image-side surfaces of each of the first to sixth lenses are aspherical mirror surfaces.

[0056] However, those skilled in the art will understand that the number of lenses constituting the imaging system can be varied to obtain the various results and advantages described herein without departing from the technical solutions claimed in this application. For example, although six lenses are described as an example in the embodiments, the imaging system is not limited to including six lenses. If desired, the imaging system may also include other numbers of lenses.

[0057] Specific embodiments of the imaging system applicable to the above-described embodiments are further described below with reference to the accompanying drawings.

[0058] Example 1

[0059] The following is for reference Figures 3 to 6D An imaging system according to Embodiment 1 of this application is described. Figures 3 to 5 Cross-sectional schematic diagrams of three imaging systems according to Embodiment 1 of this application are shown. Each of the three imaging systems may include a lens group, multiple spacer elements, and a lens barrel for housing the lens group and spacer elements. The lens groups included in the three imaging systems may have the same optical structure.

[0060] by Figure 3 The imaging system 110 shown includes a lens group as an example, which includes, in sequence along the optical axis from the object side to the image side: aperture stop STO, first lens E1, second lens E2, third lens E3, fourth lens E4, fifth lens E5, and sixth lens E6. Exemplarily, the lens group may also include a filter (not shown) disposed along the optical axis on the image side of the sixth lens E6 and an imaging surface S15 (not shown).

[0061] The first lens E1 has positive optical power, with its object-side surface S1 being convex and its image-side surface S2 being convex. The second lens E2 has negative optical power, with its object-side surface S3 being convex and its image-side surface S4 being concave. The third lens E3 has positive optical power, with its object-side surface S5 being convex and its image-side surface S6 being convex. The fourth lens E4 has positive optical power, with its object-side surface S7 being convex and its image-side surface S8 being concave. The fifth lens E5 has negative optical power, with its object-side surface S9 being concave and its image-side surface S10 being convex. The sixth lens E6 has negative optical power, with its object-side surface S11 being concave and its image-side surface S12 being concave. The filter has an object-side surface S13 and an image-side surface S14. Light from the object passes sequentially through surfaces S1 to S12 and is finally imaged onto the imaging surface S15.

[0062] Table 1 shows the basic parameters of the lens group in Example 1, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0063]

[0064] Table 1

[0065] In this embodiment, the effective focal length f1 of the first lens E1 is 8.89 mm, the effective focal length f3 of the third lens E3 is 14.49 mm, and the effective focal length f5 of the fifth lens E5 is -13.02 mm.

[0066] In this embodiment, the object-side and image-side surfaces of the lenses from the first lens E1 to the sixth lens E6 include aspherical surfaces. The following aspherical formulas can be used for limitation:

[0067] (1)

[0068] in, Let be the distance vector from the vertex of the aspherical surface at a height of h along the optical axis; c is the paraxial curvature of the aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the radius of curvature R in Table 1 above); k is the conic coefficient; Ai is the i-th order correction coefficient of the aspherical surface. Table 2 below gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for the aspherical mirrors S1 to S12 in Example 1.

[0069]

[0070] Table 2

[0071] Continue to refer to Figure 3The imaging system 110 includes a lens barrel P0 and a plurality of spacer elements, including a first spacer element P1 located between a first lens E1 and a second lens E2, a second spacer element P2 located between a second lens E2 and a third lens E3, a third spacer element P3 located between a third lens E3 and a fourth lens E4, a fourth spacer element P4 located between a fourth lens E4 and a fifth lens E5, and a fifth spacer element P5 located between a fourth lens E4 and a fifth lens E5. Exemplarily, the first spacer element P1 contacts the image-side surface S2 of the first lens E1, the second spacer element P2 contacts the image-side surface S4 of the second lens E2, and the third spacer element P3 contacts the image-side surface S6 of the third lens E3. The plurality of spacer elements also includes a spacer element P3b located between the third lens E3 and the fourth lens E4, which contacts the image-side surface of the third spacer element P3 and the object-side surface of the fourth lens E4. The fourth spacer element P4 contacts the image-side surface S8 of the fourth lens E4, and the fifth spacer element P5 contacts the image-side surface S10 of the fifth lens E5. In the imaging system 110, the first spacer element P1, the second spacer element P2, the third spacer element P3, the fourth spacer element P4, and the fifth spacer element P5 are spacers, and the spacer element P3b is a spacer ring. The spacers can be used to couple adjacent lenses and block excess external light from entering. By properly setting the positions of the spacers and each lens, the structural stability of the imaging system can be enhanced.

[0072] refer to Figure 4 The imaging system 120 may have a structure similar to that of the imaging system 110, except that in the imaging system 120, the third spacer element P3 and the fourth spacer element P4 are spacers, and the first spacer element P1, the second spacer element P2, the fifth spacer element P5 and the spacer element P3b are spacers.

[0073] refer to Figure 5 Imaging system 130 may have a structure similar to imaging systems 110 and 120. However, unlike these two imaging systems, imaging system 130 includes a spacer element P3c located between the third lens E3 and the fourth lens E4. Optionally, spacer element P3b may contact the image-side surface of the third spacer element P3, and spacer element P3c may contact the image-side surface of spacer element P3b and the object-side surface of the fourth lens E4. In imaging system 130, the first spacer element P1, the second spacer element P2, the third spacer element P3, spacer element P3c, and the fifth spacer element P5 are spacers, and spacer elements P3b and the fourth spacer element P4 are spacers.

[0074] Figure 6A The astigmatism curves of the imaging system of Example 1 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 6BThe distortion curves of the imaging system of Example 1 are shown, which represent the distortion magnitude values ​​corresponding to different image heights. Figure 6C The magnification chromatic aberration curve of the imaging system of Embodiment 1 is shown, which represents the deviation of different image heights on the imaging plane after light passes through the lens. Figure 6D The on-axis chromatic aberration curve of the imaging system of Embodiment 1 is shown, which represents the deviation of the converging focal point of light of different wavelengths after passing through the lens. According to Figures 6A to 6D It can be seen that the imaging system given in Example 1 can achieve good imaging quality.

[0075] Example 2

[0076] The following is for reference Figures 7 to 10D An imaging system according to Embodiment 1 of this application is described. Figures 7 to 9 Cross-sectional schematic diagrams of three imaging systems according to Embodiment 2 of this application are shown. Each of the three imaging systems includes a lens group, multiple spacer elements, and a lens barrel for housing the lens group and spacer elements. The lens groups included in the three imaging systems may have the same optical structure.

[0077] by Figure 7 The imaging system 210 shown includes a lens group as an example, which includes, in sequence along the optical axis from the object side to the image side: aperture stop STO, first lens E1, second lens E2, third lens E3, fourth lens E4, fifth lens E5, and sixth lens E6. Exemplarily, the lens group may also include a filter (not shown) disposed along the optical axis on the image side of the sixth lens E6 and an imaging surface S15 (not shown).

[0078] The first lens E1 has positive optical power, with its object-side surface S1 being convex and its image-side surface S2 being convex. The second lens E2 has negative optical power, with its object-side surface S3 being convex and its image-side surface S4 being concave. The third lens E3 has positive optical power, with its object-side surface S5 being concave and its image-side surface S6 being convex. The fourth lens E4 has positive optical power, with its object-side surface S7 being convex and its image-side surface S8 being concave. The fifth lens E5 has negative optical power, with its object-side surface S9 being concave and its image-side surface S10 being convex. 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 has an object-side surface S13 and an image-side surface S14. Light from the object passes sequentially through surfaces S1 to S12 and is finally imaged onto the imaging surface S15.

[0079] Table 3 shows the basic parameters of the lens group in Example 2, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0080]

[0081] Table 3

[0082] In this embodiment, the effective focal length f1 of the first lens E1 is 8.92mm, the effective focal length f3 of the third lens E3 is 15.59mm, and the effective focal length f5 of the fifth lens E5 is -10.96mm.

[0083] Table 4 gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for each aspherical mirror S1 to S12 in Example 2, wherein each aspherical surface shape can be defined by formula (1) given in Example 1 above.

[0084]

[0085] Table 4

[0086] Continue to refer to Figure 7 The imaging system 210 includes a lens barrel P0 and a plurality of spacer elements, including a first spacer element P1 located between a first lens E1 and a second lens E2, a second spacer element P2 located between a second lens E2 and a third lens E3, a third spacer element P3 located between a third lens E3 and a fourth lens E4, a fourth spacer element P4 located between a fourth lens E4 and a fifth lens E5, and a fifth spacer element P5 located between a fourth lens E4 and a fifth lens E5. Exemplarily, the first spacer element P1 contacts the image-side surface S2 of the first lens E1, the second spacer element P2 contacts the image-side surface S4 of the second lens E2, and the third spacer element P3 contacts the image-side surface S6 of the third lens E3. The plurality of spacer elements also includes a spacer element P3b located between the third lens E3 and the fourth lens E4, which contacts the image-side surface of the third spacer element P3 and the object-side surface of the fourth lens E4. The fourth spacer element P4 contacts the image-side surface S8 of the fourth lens E4, and the fifth spacer element P5 contacts the image-side surface S10 of the fifth lens E5. In the imaging system 210, the first spacer element P1, the second spacer element P2, the third spacer element P3, the fourth spacer element P4, and the fifth spacer element P5 are spacers, and the spacer element P3b is a spacer ring. The spacers can be used to couple adjacent lenses and block excess external light from entering. By properly setting the positions of the spacers and each lens, the structural stability of the imaging system can be enhanced.

[0087] refer to Figure 8 Imaging system 220 may have a structure similar to imaging system 210, except that in imaging system 220, the first spacer element P1, the second spacer element P2, the third spacer element P3 and the fifth spacer element P5 are spacers, and the spacer element P3b and the fourth spacer element P4 are spacers.

[0088] refer to Figure 9Imaging system 230 may have a structure similar to imaging systems 210 and 220. However, unlike these two imaging systems, imaging system 230 includes a spacer element P3c located between the third lens E3 and the fourth lens E4. Optionally, spacer element P3b may contact the image-side surface of the third spacer element P3, and spacer element P3c may contact the image-side surface of spacer element P3b and the object-side surface of the fourth lens E4. In imaging system 230, the first spacer element P1, the second spacer element P2, the third spacer element P3, spacer element P3c, and the fifth spacer element P5 are spacers, and spacer elements P3b and the fourth spacer element P4 are spacers.

[0089] Figure 10A The astigmatism curves of the imaging system of Example 2 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 10B The distortion curves of the imaging system of Example 2 are shown, which represent the distortion magnitude values ​​corresponding to different image heights. Figure 10C 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 10D The on-axis chromatic aberration curve of the imaging system of Embodiment 2 is shown, representing the deviation of the converging focal point of light of different wavelengths after passing through the lens. According to... Figures 10A to 10D It can be seen that the imaging system given in Example 2 can achieve good imaging quality.

[0090] Example 3

[0091] The following is for reference Figures 11 to 14D An imaging system according to Embodiment 3 of this application is described. Figures 11 to 13 Cross-sectional schematic diagrams of three imaging systems according to Embodiment 3 of this application are shown. Each of the three imaging systems may include a lens group, multiple spacer elements, and a lens barrel for housing the lens group and spacer elements. The lens groups included in the three imaging systems may have the same optical structure.

[0092] by Figure 11 The imaging system 310 shown includes a lens group as an example, which includes, in sequence along the optical axis from the object side to the image side: aperture stop STO, first lens E1, second lens E2, third lens E3, fourth lens E4, fifth lens E5, and sixth lens E6. Exemplarily, the lens group may also include a filter (not shown) disposed along the optical axis on the image side of the sixth lens E6 and an imaging surface S15 (not shown).

[0093] The first lens E1 has positive optical power, with its object-side surface S1 being convex and its image-side surface S2 being concave. The second lens E2 has negative optical power, with its object-side surface S3 being convex and its image-side surface S4 being concave. The third lens E3 has positive optical power, with its object-side surface S5 being concave and its image-side surface S6 being convex. The fourth lens E4 has positive optical power, with its object-side surface S7 being convex and its image-side surface S8 being convex. The fifth lens E5 has negative optical power, with its object-side surface S9 being concave and its image-side surface S10 being convex. 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 has an object-side surface S13 and an image-side surface S14. Light from the object passes sequentially through surfaces S1 to S12 and is finally imaged onto the imaging surface S15.

[0094] Table 5 shows the basic parameters of the lens group in Example 3, where the units for radius of curvature and thickness / distance are millimeters (mm).

[0095]

[0096] Table 5

[0097] In this embodiment, the effective focal length f1 of the first lens E1 is 9.68 mm, the effective focal length f3 of the third lens E3 is 13.81 mm, and the effective focal length f5 of the fifth lens E5 is -10.02 mm.

[0098] Table 6 gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for each aspherical mirror S1 to S12 in Example 3, wherein each aspherical surface shape can be defined by formula (1) given in Example 1 above.

[0099]

[0100] Table 6

[0101] Continue to refer to Figure 11The imaging system 310 includes a lens barrel P0 and a plurality of spacer elements, including a first spacer element P1 located between a first lens E1 and a second lens E2, a second spacer element P2 located between a second lens E2 and a third lens E3, a third spacer element P3 located between a third lens E3 and a fourth lens E4, a fourth spacer element P4 located between a fourth lens E4 and a fifth lens E5, and a fifth spacer element P5 located between a fourth lens E4 and a fifth lens E5. Exemplarily, the first spacer element P1 contacts the image-side surface S2 of the first lens E1, the second spacer element P2 contacts the image-side surface S4 of the second lens E2, and the third spacer element P3 contacts the image-side surface S6 of the third lens E3. The plurality of spacer elements also includes a spacer element P3b located between the third lens E3 and the fourth lens E4, which contacts the image-side surface of the third spacer element P3 and the object-side surface of the fourth lens E4. The fourth spacer element P4 contacts the image-side surface S8 of the fourth lens E4, and the fifth spacer element P5 contacts the image-side surface S10 of the fifth lens E5. In the imaging system 310, the first spacer element P1, the second spacer element P2, the third spacer element P3, the fourth spacer element P4, and the fifth spacer element P5 are spacers, and the spacer element P3b is a spacer ring. The spacers can be used to couple adjacent lenses and block excess external light from entering. By properly setting the positions of the spacers and each lens, the structural stability of the imaging system can be enhanced.

[0102] refer to Figure 12 The imaging system 320 may have a structure similar to that of the imaging system 310. However, in the imaging system 320, the first spacer element P1, the second spacer element P2, the spacer element P3b and the fifth spacer element P5 are spacers, and the third spacer element P3 and the fourth spacer element P4 are spacers.

[0103] refer to Figure 13 Imaging system 330 may have a structure similar to imaging systems 310 and 320. However, unlike these two imaging systems, imaging system 330 includes a spacer element P3c located between the third lens E3 and the fourth lens E4. Optionally, spacer element P3b may contact the image-side surface of the third spacer element P3, and spacer element P3c may contact the image-side surface of spacer element P3b and the object-side surface of the fourth lens E4. In imaging system 330, the first spacer element P1, the second spacer element P2, the third spacer element P3, spacer element P3c, and the fifth spacer element P5 are spacers, and spacer elements P3b and the fourth spacer element P4 are spacers.

[0104] Figure 14A The astigmatism curves of the imaging system of Example 3 are shown, which represent the meridional image plane curvature and the sagittal image plane curvature. Figure 14BThe distortion curves of the imaging system of Example 3 are shown, which represent the distortion magnitude values ​​corresponding to different image heights. Figure 14C The magnification chromatic aberration curve of the imaging system in Example 3 is shown, which represents the deviation of different image heights on the imaging plane after light passes through the lens. Figure 14D The on-axis chromatic aberration curve of the imaging system of Embodiment 3 is shown, which represents the deviation of the converging focal point of light of different wavelengths after passing through the lens. According to Figures 14A to 14D It can be seen that the imaging system given in Example 3 can achieve good imaging quality.

[0105] Table 7 shows the basic parameters of the lens barrel and spacer element in the imaging systems of Examples 1 to 3. The unit of each parameter in Table 7 is millimeters (mm).

[0106]

[0107] Table 7

[0108] In summary, Examples 1 to 3 respectively satisfy the relationships shown in Table 8.

[0109]

[0110] Table 8

[0111] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. An imaging system, characterized in that, Along the optical axis from the object side to the image side, the following are included in sequence: The first lens has positive optical power and its object-side surface is convex. The first spacer element is in contact with the image-side surface of the first lens; The second lens has negative optical power, and its object side is convex while its image side is concave. The second spacer element is in contact with the image-side surface of the second lens; The third lens has positive optical power and its image-side surface is convex. The third spacer element is in contact with the image-side surface of the third lens; The fourth lens has positive optical power and its object side is convex. The fourth spacer element is in contact with the image-side surface of the fourth lens; The fifth lens has negative optical power, with a concave object side and a convex image side. The fifth spacer element is in contact with the image-side surface of the fifth lens; The sixth lens has negative optical power and its image-side surface is concave; wherein, at least one of the first to the sixth lens is an aspherical lens, and the radius of curvature R2 of the image-side surface of the first lens, the radius of curvature R12 of the image-side surface of the sixth lens, the outer diameter D2m of the image-side surface of the second spacer element, the outer diameter D5m of the image-side surface of the fifth spacer element, and the distance EP34 between the third and fourth spacer elements on the optical axis, the distance EP45 between the fourth and fifth spacer elements on the optical axis, the center thickness CT3 of the third lens on the optical axis, and the center thickness CT4 of the fourth lens on the optical axis satisfy: -12.74≤(R2 / D2m)+(R12 / D5m)≤12.58 and -7.0<(EP34+EP45) / (CT3-CT4)≤-3.73; The imaging system has six lenses with optical power.

2. The imaging system according to claim 1, characterized in that, The effective focal length f1 of the first lens, the effective focal length f5 of the fifth lens, the thickness CP1 of the first spacer element, and the thickness CP5 of the fifth spacer element satisfy the following condition: -229.58≤f5 / CP5+f1 / CP1≤-18.

73.

3. The imaging system according to claim 1, characterized in that, The radius of curvature R8 of the image side of the fourth lens, the inner diameter d2m of the image side of the second spacer element, and the inner diameter d3m of the image side of the third spacer element satisfy the following condition: 4.65≤|R8 / (d3m+d2m)|≤8.

94.

4. The imaging system according to claim 1, characterized in that, The thickness CP3 of the third spacer element, the distance EP23 between the second spacer element and the third spacer element on the optical axis, the distance T23 between the second lens and the third lens on the optical axis, and the center thickness CT3 of the third lens on the optical axis satisfy the following condition: 1.89≤T23 / CP3+EP23 / CT3≤60.

81.

5. The imaging system according to claim 1, characterized in that, The distance T45 between the fourth lens and the fifth lens on the optical axis, the outer diameter D4s of the object side of the fourth spacer element, the inner diameter d4s of the object side of the fourth spacer element, and the thickness CP4 of the fourth spacer element satisfy the following: 7.54≤(D4s+d4s) / (CP4+T45)≤15.

42.

6. The imaging system according to claim 1, characterized in that, The radius of curvature R5 of the object side of the third lens, the sum of the distances ∑AT between any two adjacent lenses from the first lens to the sixth lens on the optical axis, and the sum of the distances ∑EP between any two adjacent spacers from the first spacer element to the fifth spacer element on the optical axis satisfy: 24.65≤|R5 / (∑EP-∑AT)|≤44.

42.

7. The imaging system according to claim 1, characterized in that, The sum of the thicknesses of the first to the fifth spacers, ∑CP, the radius of curvature of the object side surface of the sixth lens, and the sum of the center thicknesses of the first to the sixth lenses on the optical axis, ∑CT, satisfy: 9.92≤|R11 / (∑CP+∑CT)|≤12.

54.

8. The imaging system according to claim 1, characterized in that, The effective focal length f3 of the third lens, the effective focal length f5 of the fifth lens, the center thickness CT3 of the third lens on the optical axis, the center thickness CT5 of the fifth lens on the optical axis, the thickness CP3 of the third spacer element, the thickness CP5 of the fifth spacer element, the outer diameter D5s of the object side of the fifth spacer element, and the inner diameter d5m of the image side of the fifth spacer element satisfy the following: -24.0<(f5 CP3 CT5 CT3-f3 CP5 CT5 CT3) / (CP3 CP5 D5s d5m)≤-10.37。 9. The imaging system according to claim 1, characterized in that, Also includes: A lens barrel for accommodating each lens and each spacer element, wherein the dimension L of the lens barrel along the optical axis, the radius of curvature R2 of the image side surface of the first lens, and the radius of curvature R12 of the image side surface of the sixth lens satisfy the following: -14.40≤(R2-R12) / L≤6.87.

Images