Grouping telephoto lens

Abstract

The invention discloses a grouping telephoto lens. The grouping telephoto lens comprises a first lens group, a turn-back prism, a second lens group and a chip imaging assembly, the turn-back prism comprises a light inlet side and a light outlet side, and the light inlet side and / or the light outlet side of the turn-back prism are / is provided with a light filtering film; the first lens group comprises at least three lenses which are arranged in front of the light inlet side of the turn-back prism; the second lens group comprises at least one lens which is arranged behind the light emitting side of the turn-back prism or is arranged close to the light inlet side of the turn-back prism and is positioned between the first lens group and the light inlet side of the turn-back prism; the first lens group and / or the second lens group move / moves in the optical axis direction for focusing. The grouping telephoto lens provided by the invention meets the requirement of miniaturization.

Description

Technical Field

[0001] The present invention relates to the field of optical imaging technology, and in particular to a grouping telephoto lens. Background Art

[0002] With the rapid development of mobile communication technology and the popularization of smartphones, the functions and application scenarios of mobile phone lenses are constantly enriching and expanding. Among them, telephoto lenses, as a functional module that enables long-distance shooting and optical zoom, have attracted widespread attention in the smartphone market.

[0003] However, to capture distance and quality images, a telephoto lens necessarily requires a long focal length and a large aperture. This also requires a sufficiently large size, creating a trade-off between size, macro range, and zoom ratio. This makes it impossible to achieve a balance between performance and size, making it difficult to miniaturize telephoto lenses. Existing technologies that use prisms to fold the optical path and increase the optical range have achieved significant success in recent years, but these same trade-offs still exist. Summary of the Invention

[0004] In view of the above problems, an object of the present invention is to provide a group telephoto lens, which can achieve a smaller volume and meet the demand for miniaturization.

[0005] The present invention provides a grouped telephoto lens, which includes a first lens group, a folding prism, a second lens group and a chip imaging component; the folding prism includes a light input side and a light output side, and a filter film is provided on the light input side and / or the light output side of the folding prism; the first lens group includes at least three lenses, which are arranged before the light input side of the folding prism; the second lens group includes at least one lens, which is arranged after the light output side of the folding prism, or is arranged adjacent to the light input side of the folding prism, and is located between the first lens group and the light input side of the folding prism; the first lens group and / or the second lens group moves along the optical axis to focus.

[0006] Optionally, if the first lens group is arranged before the light-incoming side of the folding prism, and the second lens group is arranged after the light-outgoing side of the folding prism, the distance M1 from the bottom of the folding prism to the axial outermost point of the object-side surface of the lens of the first lens group closest to the object side, and the distance M2 from the bottom of the folding prism to the bottom surface of the circuit board where the chip imaging component is located, satisfy: M2+0.5<M1<M2+4.

[0007] Optionally, if the first lens group is arranged before the light-incoming side of the folding prism, and the second lens group is arranged after the light-outgoing side of the folding prism, the distance M1 from the bottom of the folding prism to the axial outermost point of the object-side surface of the lens of the first lens group closest to the object side, and the distance M2 from the bottom of the folding prism to the bottom surface of the circuit board where the chip imaging component is located, and the total optical length M3 of the group telephoto lens satisfy: M1+M2<M3-2.

[0008] Optionally, a distance M4 between the intersection of the zero-field chief ray at the second reflecting surface of the folding prism and the incident optical axis satisfies: M4 ≥ 3.5 mm.

[0009] Optionally, if the first lens group is arranged before the light-entering side of the folding prism, and the second lens group is arranged after the light-exiting side of the folding prism, in the far-focus state, the distance H8a between the lens of the first lens group closest to the folding prism and the folding prism along the optical axis, and in the near-focus state, the distance H8b between the lens of the first lens group closest to the folding prism and the folding prism along the optical axis, the near-focus object distance H0, and the system focal length f' of the grouped telephoto lens satisfy: ABS(H8a-H8b) / (f'*H0 / (H0-f')-f')≤1.

[0010] Optionally, the optical power EFX1 of the first lens group and the system focal length f' of the group telephoto lens satisfy: EFX1 / f'<1.

[0011] Optionally, the second lens group includes a fourth lens, and an equivalent thickness H9 of the folding prism and a center thickness H11 of the fourth lens satisfy: 0.01≤H11 / H9≤0.1.

[0012] Optionally, an equivalent thickness H9 of the folding prism and a system focal length f' of the group telephoto lens satisfy the following relationship: 0.25≤f' / H9≤1.2.

[0013] Optionally, the second lens group includes a fourth lens, and a focal length f4 of the fourth lens and a system focal length f' of the group telephoto lens satisfy: -5≤f4 / f'≤0.

[0014] Optionally, the object-side surface of the lens closest to the object in the first lens group has a curvature radius C3, the second lens group includes a fourth lens, and the object-side surface of the fourth lens has a curvature radius C12 that satisfies: 0.5≤C3 / C12≤1.8.

[0015] The clustered telephoto lens provided by the present invention includes a first lens group, a folding prism, a second lens group, and a chip imaging assembly. The first and second lens groups can be used to focus and form an image. Multiple light path reflections through the folding prism achieve light path folding, significantly reducing the overall height and shoulder height of the clustered telephoto lens. Furthermore, the folding prism includes a light-input side and a light-output side. Filter films are provided on the light-input and / or light-output sides of the folding prism, further reducing the height of the lens module. Consequently, the clustered telephoto lens can be smaller in size, meeting miniaturization requirements while maintaining the same optical performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 A schematic diagram of the structure of a group telephoto lens after folding the optical path according to an embodiment of the present application is shown.

[0018] Figure 2 and Figure 3 Schematic diagrams of the front structure of the folded optical path of the group telephoto lens in the far focus state and the near focus state according to Example 1 of the present application are respectively shown.

[0019] Figure 4 and Figure 5 The MTF curves of the group telephoto lens of Example 1 in the far focus state and the near focus state are shown respectively.

[0020] Figure 6 and Figure 7 Schematic diagrams of the front structure of the folded optical path of the group telephoto lens in the far focus state and the near focus state according to Example 2 of the present application are respectively shown.

[0021] Figure 8 and Figure 9 The MTF curves of the group telephoto lens of Example 2 in the far focus state and the near focus state are shown respectively.

[0022] Figure 10 and Figure 11 Schematic diagrams of the front structure of the folded optical path of the group telephoto lens in the far focus state and the near focus state according to Example 3 of the present application are respectively shown.

[0023] Figure 12 and Figure 13 The MTF curves of the group telephoto lens of Example 3 in the far focus state and the near focus state are shown respectively. DETAILED DESCRIPTION

[0024] The aforementioned and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of the preferred embodiments with reference to the drawings. Through the description of the specific embodiments, a deeper and more specific understanding of the technical means and effects adopted by the present invention to achieve the intended purpose can be obtained. However, the accompanying drawings are only for reference and illustration purposes and are not intended to limit the present invention. Some well-known parts may not be shown. In the various drawings, the same elements are represented by similar reference numerals. For the sake of clarity, the various parts in the drawings are not necessarily drawn strictly according to the actual scale.

[0025] It should be understood that the terms "first," "second," "third," and "fourth," etc., are intended only to distinguish between components or circuits having similar properties, and do not indicate or imply relative importance or a particular order. The terms "comprise," "include," or any other variation thereof, are intended to cover a non-exclusive inclusion, and may include, in addition to the listed elements, other elements not explicitly listed.

[0026] In the drawings, the thickness, size, and shape of the lenses are slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical surfaces shown in the drawings are provided by way of example. That is, the shapes of the spherical surfaces are not limited to those shown in the drawings. The drawings are for illustration only and are not drawn strictly to scale.

[0027] In this article, the paraxial region refers to the area near the optical axis. If a lens surface is convex and the location of the convex surface is undefined, it means that the lens surface is convex at least in the paraxial region. If a lens surface is concave and the location of the concave surface is undefined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the subject is called the object-side surface of the lens, and the surface of each lens closest to the image plane is called the image-side surface of the lens.

[0028] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments in this application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0029] The features, principles and other aspects of the present application are described in detail below.

[0030] Please refer to Figure 1 , Figure 1 A schematic diagram of the structure of a group telephoto lens after folding the optical path according to an embodiment of the present application is shown.

[0031] According to the exemplary embodiment of the present application, the grouped telephoto lens includes a first lens group 10, a return prism P1, a second lens group 20 and a chip imaging component 30; the return prism P1 includes a light input side and a light output side, and a filter film is provided on the light input side and / or the light output side of the return prism P1; the first lens group 10 includes at least three lenses, which are arranged before the light input side of the return prism P1; the second lens group 20 includes at least one lens, which is arranged after the light output side of the return prism P1, or is arranged adjacent to the light input side of the return prism P1, and is located between the first lens group 10 and the light input side of the return prism P1; the first lens group 10 and / or the second lens group 20 moves along the optical axis for focusing.

[0032] The folding prism P1 includes a light-incoming side and a light-outgoing side. Figure 1 As shown, the light-entering side and the light-emitting side can be the same surface; however, the present application is not limited thereto. For example, the light-entering side and the light-emitting side can be at the top and bottom of the folding prism P1, respectively, or at the top and waist of the folding prism P1, etc. After the light enters the folding prism P1 from the light-entering side, it can be reflected at least twice and then emitted from the light-emitting side. If the first lens group 10 is arranged before the light-entering side of the folding prism P1; and the second lens group 20 is arranged after the light-emitting side of the folding prism P1, the light can sequentially penetrate the first lens group 10, the folding prism P1, and the second lens group 20, and finally be projected onto the imaging surface IMG of the chip imaging component 30. If the first lens group 10 is arranged in front of the light-entering side of the returning prism P1; the second lens group 20 is set adjacent to the light-entering side of the returning prism P1, and is located between the first lens group 10 and the light-entering side of the returning prism P1, then the light can penetrate the first lens group 10, the second lens group 20 and the returning prism P1 in sequence, and finally be projected onto the imaging surface IMG of the chip imaging component 30.

[0033] Among them, the folding prism P1 can perform multiple light path reflections to achieve light path folding, changing the original straight-line direction of the light. The lens back focus optical path can be folded inside the folding prism P1, so that the light emitted from the folding prism P1 can reach the imaging surface IMG through a smaller optical path, which correspondingly shortens the lens back focus length and can significantly reduce the overall height and shoulder height of the lens module. By reasonably allocating the optical focal length, spacing and refractive index of each lens in the first lens group 10 and the second lens group 20, the angle and thickness of the folding prism P1 can significantly reduce the overall height and shoulder height of the grouped telephoto lens. In addition, the folding prism P1 includes a light input side and a light output side. The light input side and / or light output side of the folding prism P1 are provided with a filter film, which can further reduce the height of the lens module.

[0034] The first lens group 10 and / or the second lens group 20 move along the optical axis for AF, achieving excellent image quality at close focus, for example, 20 cm, and at infinity. Optionally, the first lens group 10 can also move along the optical axis for AF and in the X and Y directions (the optical axis is the Z axis) to achieve optical image stabilization (OIS). Furthermore, this grouping allows the AF and OIS travel to be reduced to 50%-80% of the conventional focus travel, meeting height requirements and facilitating miniaturization of the lens module.

[0035] Therefore, the clustered telephoto lens according to the embodiment of the present invention can achieve a smaller volume of the clustered telephoto lens, meeting the demand for miniaturization.

[0036] In an exemplary embodiment, according to the clustered telephoto lens of the present application, the first lens group 10 may include at least three lenses, for example, three, four, or five lenses; the lenses may be molded spherically or aspherically. In one exemplary embodiment, the lens closest to the object in the first lens group 10 has positive optical power and can perform a light-gathering function. In one exemplary embodiment, Figure 1 As shown, the first lens group 10 includes, from the object side to the image side, a first lens L1, a second lens L2, and a third lens L3. The first lens L1 has positive refractive power, the second lens L2 has negative refractive power, and the third lens L3 has positive refractive power. In one exemplary embodiment, the second lens L2 can be meniscus-shaped, with its object-side surface being concave.

[0037] In an exemplary embodiment, Figure 1 As shown, according to the clustered telephoto lens of the present application, the second lens group 20 comprises only one lens, which reduces the module shoulder height. This lens is the fourth lens L4, which can be molded spherically or aspherically. In one exemplary embodiment, the fourth lens L4 has negative power to correct chromatic aberration. In another exemplary embodiment, the central portion of the fourth lens L4 is convex toward the object, and the object-side profile of the fourth lens L4 has two valleys, one on each side extending from the central portion.

[0038] In an exemplary embodiment, according to the group telephoto lens of the present application, the materials of the lenses in the first lens group 10 and the second lens group 20 can be glass, plastic, or a glass-plastic hybrid.

[0039] In an exemplary embodiment, the cluster telephoto lens according to the present application further includes an aperture stop STO. Preferably, the aperture stop STO is disposed on the object-side surface of the lens closest to the object in the first lens group 10. However, the present application is not limited thereto; the aperture stop STO may also be disposed between two adjacent lenses in the plurality of lenses in the first lens group 10, for example.

[0040] In an exemplary embodiment, Figure 1As shown, according to the clustered telephoto lens of the present application, if the first lens group 10 is arranged before the light-entering side of the folding prism P1, and the second lens group 20 is arranged after the light-exiting side of the folding prism P1, the distance M1 from the bottom of the folding prism P1 to the axial outermost point of the object-side surface of the lens closest to the object of the first lens group 10, and the distance M2 from the bottom of the folding prism P1 to the bottom surface of the circuit board 40 where the chip imaging component 30 is located, satisfy: M2+0.5<M1<M2+4. By controlling the distance M1 from the bottom of the folding prism P1 to the axial outermost point of the object-side surface of the lens closest to the object of the first lens group 10, and the distance M2 from the bottom of the folding prism P1 to the bottom surface of the circuit board 40 where the chip imaging component 30 is located, it is beneficial to reduce the shoulder height of the lens module and achieve miniaturization of the lens module.

[0041] In an exemplary embodiment, Figure 1 As shown, according to the cluster telephoto lens of the present application, if the first lens group 10 is arranged before the light-entering side of the folding prism P1, and the second lens group 20 is arranged after the light-exiting side of the folding prism P1, the distance M1 from the bottom of the folding prism P1 to the axial outermost point of the object-side surface of the lens closest to the object side of the first lens group 10, and the distance M2 from the bottom of the folding prism P1 to the bottom surface of the circuit board 40 where the chip imaging component 30 is located, the total optical length M3 of the cluster telephoto lens ( Figure 2 (not shown), satisfying: M1 + M2 < M3 - 2. By controlling the distance M1 from the bottom of the folding prism P1 to the axially outermost point of the object-side surface of the lens closest to the object in the first lens group 10, the distance M2 from the bottom of the folding prism P1 to the bottom surface of the circuit board 40 where the chip imaging assembly 30 is located, and the total optical length M3 of the clustered telephoto lens, the total optical length of the system can be reduced, achieving miniaturization of the lens module.

[0042] In an exemplary embodiment, Figure 1 As shown, the clustered telephoto lens of the present application can meet the requirement of M4 ≥ 3.5 mm, where M4 is the distance between the intersection of the zero-field chief ray on the second reflective surface of the folding prism P1 and the incident optical axis. Meeting M4 ≥ 3.5 mm facilitates lens module assembly by controlling the range of the distance M4 between the intersection of the zero-field chief ray on the second reflective surface of the folding prism P1 and the incident optical axis.

[0043] In an exemplary embodiment, Figure 1As shown, according to the grouped telephoto lens of the present application, if the first lens group 10 is arranged before the light-entering side of the return prism P1, and the second lens group 20 is arranged after the light-exiting side of the return prism P1, in the far-focus state, the distance H8a between the lens of the first lens group 10 closest to the return prism P1 and the return prism P1 along the optical axis, in the near-focus state, the distance H8b between the lens of the first lens group 10 closest to the return prism P1 and the return prism P1 along the optical axis, the near-focus object distance H0, and the system focal length f' of the grouped telephoto lens satisfy: ABS(H8a-H8b) / (f'*H0 / (H0-f')-f')≤1. This can help reduce the stroke when the lens is focusing, and is beneficial to the miniaturization of the lens module.

[0044] In an exemplary embodiment, the cluster telephoto lens of the present application can satisfy EFX1 / f'<1, where EFX1 is the optical power of first lens group 10, and f' is the system focal length of the cluster telephoto lens. Controlling the ratio of the optical power EFX1 of first lens group 10 to the system focal length f' of the cluster telephoto lens facilitates aberration correction and improves imaging quality.

[0045] In an exemplary embodiment, Figure 1 As shown, according to the clustered telephoto lens of the present application, 0.01≤H11 / H9≤0.1 can be satisfied. Specifically, the second lens group 20 includes the fourth lens L4, H9 is the equivalent thickness of the folding prism P1, and H11 is the center thickness of the fourth lens L4. The satisfaction of 0.01≤H11 / H9≤0.1 is achieved by controlling the ratio range of the center thickness H11 of the fourth lens L4 and the equivalent thickness H9 of the folding prism P1, which helps control the height of the prism light exit surface module, thereby reducing the shoulder height of the lens module and achieving miniaturization of the lens module.

[0046] In an exemplary embodiment, the clustered telephoto lens of the present application can satisfy the condition 0.25≤f' / H9≤1.2, where H9 is the equivalent thickness of the folding prism P1 and f' is the system focal length of the clustered telephoto lens. By controlling the ratio of the equivalent thickness H9 of the folding prism P1 to the system focal length f' of the clustered telephoto lens, the prism thickness can be kept within a reasonable range, which can optimize optical system aberrations, reduce system volume, and achieve miniaturization of the lens module.

[0047] In an exemplary embodiment, the cluster telephoto lens of the present application can satisfy -5 ≤ f4 / f' ≤ 0. The second lens group 20 includes a fourth lens L4, where f4 is the focal length of the fourth lens L4, and f' is the system focal length of the cluster telephoto lens. Controlling the ratio of the focal length f4 of the fourth lens L4 to the system focal length f' of the cluster telephoto lens facilitates distortion correction and improves image quality.

[0048] In an exemplary embodiment, the clustered telephoto lens of the present application can satisfy 0.5 ≤ C3 / C12 ≤ 1.8, where C3 is the radius of curvature of the object-side surface of the lens closest to the object in the first lens group 10, and C12 is the radius of curvature of the object-side surface of the second lens group 20 including the fourth lens L4. The requirement of 0.5 ≤ C3 / C12 ≤ 1.8 is achieved by controlling the ratio of the radius of curvature C3 of the object-side surface of the lens closest to the object in the first lens group 10 to the radius of curvature C12 of the object-side surface of the fourth lens L4, thereby facilitating the system focal length and improving imaging quality.

[0049] In an exemplary embodiment, the cluster telephoto lens of the present application can satisfy 0.2 ≤ f1 / f' ≤ 1. The first lens group 10 includes the first lens L1 closest to the object, where f1 is the focal length of the first lens L1, and f' is the system focal length of the cluster telephoto lens. This 0.2 ≤ f1 / f' ≤ 1 requirement is achieved by controlling the ratio of the focal length f1 of the first lens L1 to the system focal length f' of the cluster telephoto lens, thereby facilitating light convergence and achieving a large aperture.

[0050] In an exemplary embodiment, the clustered telephoto lens of the present application can satisfy 0.01≤AB1 / N1≤0.05. First lens group 10 includes first lens L1, which is closest to the object side. AB1 is the Abbe number of first lens L1, and N1 is the refractive index of first lens L1. Controlling the ratio of Abbe number AB1 to refractive index N1 of first lens L1 facilitates chromatic aberration correction and achieves high image quality at large apertures.

[0051] In an exemplary embodiment, the clustered telephoto lens of the present application can satisfy 1≤Np≤1.9, where Np is the refractive index of the folding prism P1. Controlling the range of the refractive index Np of the folding prism P1 facilitates controlling the signal-to-noise ratio of the system and improving imaging quality.

[0052] In an exemplary embodiment, the clustered telephoto lens of the present application can satisfy 0.25 mm ≤ H12 ≤ 14 mm, where H12 is the distance from the object-side surface of the lens closest to the imaging plane IMG in the second lens group 20 to the imaging plane IMG. By controlling the range of distance H12 from the object-side surface of the lens closest to the imaging plane IMG in the second lens group 20, the likelihood of spot smear imaging can be reduced, thereby improving image quality.

[0053] In an exemplary embodiment, the folding prism P1 can be modified by cutting or rounding the corners. The cutting and rounding of the corners are coated, silk-screened, etc. to suppress the influence of stray light, which helps to improve the reliability of the module and reduce stray light.

[0054] In an exemplary embodiment, the auto focus (AF) drive of the first lens group 10 may be a voice coil motor (VCM), and its motion guide structure may be a suspension wire, a spring, a ball bearing, or a guide rod.

[0055] Based on the same inventive concept, an electronic device according to an exemplary embodiment of the present application includes the aforementioned clustered telephoto lens. The electronic device may be, but is not limited to, a smartphone, a tablet computer, a laptop computer, a pan / tilt camera, a surveillance camera, an in-vehicle monitoring device, or other imaging device. The implementation of this electronic device can be referenced in the examples of the clustered telephoto lens, and any repetitive details will not be repeated here.

[0056] However, those skilled in the art will appreciate that the number of lenses comprising the optical imaging lens can be varied to achieve the various results and advantages described herein without departing from the claimed technical solutions. For example, while the embodiments describe four lenses as an example, the optical imaging lens is not limited to four lenses. If desired, the optical imaging lens may also include other numbers of lenses.

[0057] Specific embodiments of the group telephoto lens applicable to the above-mentioned embodiments will be further described below with reference to the accompanying drawings.

[0058] Example 1 The following reference Figure 2 and Figure 3 The following describes a grouped telephoto lens according to embodiment 1 of the present application. Figure 2 and Figure 3 Schematic diagrams of the front structure of the folded optical path of the group telephoto lens in the far focus state and the near focus state according to Example 1 of the present application are respectively shown.

[0059] like Figure 2 and Figure 3As shown, the clustered telephoto lens includes a first lens group 10, a folding prism P1, a second lens group 20, and a chip imaging assembly 30. The folding prism P1 includes a light-entry side and a light-exit side, with a filter film disposed on the light-entry side and / or the light-exit side of the folding prism P1. The first lens group 10 is positioned before the light-entry side of the folding prism P1, and the second lens group 20 is positioned after the light-exit side of the folding prism P1. In other embodiments, the first lens group 10 is positioned before the light-entry side of the folding prism P1, and the second lens group 20 is positioned immediately adjacent to the light-entry side of the folding prism P1 and between the first lens group 10 and the light-entry side of the folding prism P1. The first lens group 10 and / or the second lens group 20 move along the optical axis for focusing. The first lens group 10 includes, from the object side to the image side, a first lens L1, a second lens L1, and a third lens L3. The second lens group 20 includes a fourth lens L4. An aperture stop STO may be disposed on the object-side surface of the first lens L1.

[0060] Please also refer to the following Figure 2 、 Figure 3 As shown in Table 1, the first lens L1 has positive optical power, and its object side surface is convex, and its image side surface is convex. The second lens L2 has negative optical power, its object side surface is concave, and its image side surface is convex. The third lens L3 has positive optical power, its object side surface is convex, and its image side surface is convex. The return prism P1 has a light input side and a light output side. The fourth lens L4 has positive optical power, its object side surface is convex, and its image side surface is concave. The light from the object first passes through the first lens group 10, specifically the aperture STO, the first lens L1, the second lens L2 and the third lens L3; then enters the return prism P1 through the light input side, is reflected at least twice inside the return prism P1, and is emitted through the light output side; then passes through the second lens group 20, that is, the fourth lens L4, and is projected onto the imaging surface IMG of the chip imaging component 30.

[0061] Table 1 shows the basic parameters of the cluster telephoto lens of Example 1, wherein the units of curvature radius, thickness and focal length are all millimeters (mm).

[0062] Table 1:

[0063] Among them, L1 R1 represents the object-side surface of the first lens L1, and L1 R2 represents the image-side surface of the first lens L1; L2 R1 represents the object-side surface of the second lens L2, and L2 R2 represents the image-side surface of the second lens L2; ​​L3 R1 represents the object-side surface of the third lens L3, and L3 R2 represents the image-side surface of the third lens L3; Prism R1 represents the light-incoming side of the returning prism P1, and Prism R2 represents the light-outgoing side of the returning prism P1; L4 R1 represents the object-side surface of the fourth lens L4, and L4 R2 represents the image-side surface of the fourth lens L4. The surface number "8 L3 R2" corresponds to a thickness of "0.45 / 1.43." 0.45mm represents the distance H8a along the optical axis between the third lens element L3 (i.e., the lens closest to the folding prism P1 in the first lens group 10) and the folding prism P1 in the far focus state. 1.43mm represents the distance H8b along the optical axis between the third lens element L3 (i.e., the lens closest to the folding prism P1 in the first lens group 10) and the folding prism P1 in the near focus state at a macro distance of, for example, 20cm. The sign of the radius of curvature is determined by the left or right of the surface's center, with the object side on the left and the image side on the right. If the surface is to the left of the center, the radius of curvature is positive; if it is to the right, the radius of curvature is negative.

[0064] In Example 1, the object-side surface and the image-side surface of any lens from the first lens L1 to the fourth lens L4 may both be even-order aspheric surfaces. The shape of the aspheric surface may be defined by, but not limited to, the following aspheric surface formula: (1) Wherein, x is the distance vector height from the vertex of the extended aspheric surface when the extended aspheric surface is at a height of h along the optical axis; c is the paraxial curvature of the extended aspheric surface, c = 1 / R (that is, the paraxial curvature c is the inverse of the curvature radius in Table 1 above); k is the cone coefficient; Ai is the correction coefficient of the i-th order of the extended aspheric surface.

[0065] Table 2 shows the conic coefficients and higher-order coefficients A2, A4, A6, A8, A10, A12, A14, A16, A18, and A20 when the object-side surfaces and image-side surfaces of the first lens L1 to the fourth lens L4 in Example 1 are even-order aspheric surfaces.

[0066] Table 2:

[0067] In Example 1, the cluster telephoto lens has a system focal length f' of 13.85 mm, an aperture value F# of 2.65, an image circle diameter of 8.24 mm, and an operating wavelength range of 420-380 nm. In the telephoto state, the distance H8a along the optical axis between the third lens element L3 (i.e., the lens element in the first lens group 10 closest to the folding prism P1) and the folding prism P1; in the near-focus state, the distance H8b along the optical axis between the third lens element L3 (i.e., the lens element in the first lens group 10 closest to the folding prism P1) and the folding prism P1; the near-focus object distance H0 (e.g., 20 cm); and the system focal length f' of the cluster telephoto lens are related by the equation ABS(H8a-H8b) / (f'*H0 / (H0-f')-f')=0.95, satisfying ABS(H8a-H8b) / (f'*H0 / (H0-f')-f')≤1. The central thickness H11 of the fourth lens element L4 and the equivalent thickness H9 of the folding prism P1 are related by the equation H11 / H9=0.035, satisfying 0.01≤H11 / H9≤0.1. The equivalent thickness H9 of the folding prism P1 and the system focal length f' of the cluster telephoto lens are related by the equation f' / H9=0.962, satisfying 0.25≤f' / H9≤1.2. The focal length f1 of the first lens element L1 and the system focal length f' of the cluster telephoto lens are related by the equation f1 / f'=0.604, satisfying 0.2≤f1 / f'≤1. The focal length f4 of the fourth lens element L4 and the system focal length f' of the cluster telephoto lens are related by the equation f4 / f'=-1.716, satisfying -5≤f4 / f'≤0. The Abbe number AB1 of first lens L1 and its refractive index N1 are related by the equation AB1 / N1=0.028, satisfying 0.01≤AB1 / N1≤0.05. The radius of curvature C3 of the object-side surface of the lens closest to the object in first lens group 10 and the radius of curvature C12 of the object-side surface of fourth lens L4 are related by the equation C3 / C12=1.429, satisfying 0.5≤C3 / C12≤1.8. The refractive index Np of folding prism P1 is 1.680, satisfying 1≤Np≤1.9. The distance H12 from the object-side surface of the lens closest to imaging plane IMG in second lens group 20 to imaging plane IMG is 1.410 mm, satisfying 0.25 mm≤H12≤14 mm.

[0068] Figure 4 The MTF curve and MTF (Modulation Transfer Function) curve of the clustered telephoto lens of Example 1 in the telephoto state are shown. The MTF curve shows the imaging system's transmission of image details (i.e., image contrast) at different spatial frequencies. At infinity and a spatial frequency of 125 lp / mm, the OTF modulus is greater than 0.2, indicating excellent resolution. Figure 5The MTF curve of the cluster telephoto lens of Example 1 at close focus state and the MTF (Modulation Transfer Function) curve are shown. The MTF curve shows the transmission of image details (i.e. image contrast) of the imaging system at different spatial frequencies. The OTF modulus is greater than 0.1 at a close focus of 20cm and a spatial frequency of 120lp / mm, indicating good resolution. Figures 4 and 5 It can be seen that the group telephoto lens provided in Example 1 has good resolution in both the far-focus state and the near-focus state, and can achieve good imaging quality.

[0069] Example 2 The following reference Figure 6 and Figure 7 The following describes a grouped telephoto lens according to embodiment 2 of the present application. Figure 6 and Figure 7 Schematic diagrams of the front structure of the folded optical path of the group telephoto lens in the far focus state and the near focus state according to Example 2 of the present application are respectively shown.

[0070] like Figure 6 and Figure 7 As shown, the clustered telephoto lens includes a first lens group 10, a folding prism P1, a second lens group 20, and a chip imaging assembly 30. The folding prism P1 includes a light-entry side and a light-exit side, and a filter film is provided on the light-entry side and / or the light-exit side of the folding prism P1. The first lens group 10 is arranged before the light-entry side of the folding prism P1, and the second lens group 20 is arranged after the light-exit side of the folding prism P1. In other embodiments, the first lens group 10 is arranged before the light-entry side of the folding prism P1, and the second lens group 20 is arranged immediately adjacent to the light-entry side of the folding prism P1 and located between the first lens group 10 and the light-entry side of the folding prism P1. The first lens group 10 and / or the second lens group 20 move along the optical axis for focusing. The first lens group 10 includes, from the object side to the image side, a first lens L1, a second lens L2, and a third lens L3. The second lens group 20 includes a fourth lens L4. A stop STO may be provided on the object-side surface of the first lens L1.

[0071] Please also refer to the following Figure 6 、 Figure 7As shown in Table 3, the first lens L1 has positive optical power, and its object side surface is convex, and its image side surface is convex. The second lens L2 has negative optical power, its object side surface is concave, and its image side surface is convex. The third lens L3 has positive optical power, its object side surface is concave, and its image side surface is convex. The return prism P1 has a light input side and a light output side. The fourth lens L4 has positive optical power, its object side surface is convex, and its image side surface is concave. The light from the object first passes through the first lens group 10, specifically the aperture STO, the first lens L1, the second lens L2 and the third lens L3; then enters the return prism P1 through the light input side, is reflected at least twice inside the return prism P1, and is emitted through the light output side; then passes through the second lens group 20, that is, the fourth lens L4, and is projected onto the imaging surface IMG of the chip imaging component 30.

[0072] Table 3 shows the basic parameters of the cluster telephoto lens of Example 2, where the units of curvature radius, thickness and focal length are all millimeters (mm).

[0073] Table 3:

[0074] Table 4 shows the conic coefficients and higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 of the object-side and image-side surfaces of the first to fourth lenses L1 to L4, which can be used in Example 2, when the surfaces are even-order aspheric surfaces. The surface shape of each even-order aspheric surface can be defined by formula (1) given in Example 1.

[0075] Table 4:

[0076] In Example 2, the cluster telephoto lens has a system focal length f' of 13.81 mm, an aperture value F# of 2.65, an image circle diameter of 8.33 mm, and an operating wavelength range of 420-380 nm. In the telephoto state, the distance H8a along the optical axis between the third lens L3 (i.e., the lens closest to the folding prism P1 in the first lens group 10) and the folding prism P1; in the near-focus state, the distance H8b along the optical axis between the third lens L3 (i.e., the lens closest to the folding prism P1 in the first lens group 10) and the folding prism P1; the near-focus object distance H0 (e.g., 20 cm); and the system focal length f' of the cluster telephoto lens are related by the equation ABS(H8a-H8b) / (f'*H0 / (H0-f')-f')=0.95, satisfying ABS(H8a-H8b) / (f'*H0 / (H0-f')-f')≤1. The central thickness H11 of the fourth lens element L4 and the equivalent thickness H9 of the folding prism P1 are related by the equation H11 / H9=0.035, satisfying 0.01≤H11 / H9≤0.1. The equivalent thickness H9 of the folding prism P1 and the system focal length f' of the cluster telephoto lens are related by the equation f' / H9=0.962, satisfying 0.25≤f' / H9≤1.2. The focal length f1 of the first lens element L1 and the system focal length f' of the cluster telephoto lens are related by the equation f1 / f'=0.564, satisfying 0.2≤f1 / f'≤1. The focal length f4 of the fourth lens element L4 and the system focal length f' of the cluster telephoto lens are related by the equation f4 / f'=-1.791, satisfying -5≤f4 / f'≤0. The Abbe number AB1 of first lens L1 and its refractive index N1 are related by the equation AB1 / N1=0.028, satisfying 0.01≤AB1 / N1≤0.05. The radius of curvature C3 of the object-side surface of the lens closest to the object in first lens group 10 and the radius of curvature C12 of the object-side surface of fourth lens L4 are related by the equation C3 / C12=1.349, satisfying 0.5≤C3 / C12≤1.8. The refractive index Np of folding prism P1 is 1.720, satisfying 1≤Np≤1.9. The distance H12 from the object-side surface of the lens closest to imaging plane IMG in second lens group 20 to imaging plane IMG is 1.405 mm, satisfying 0.25 mm≤H12≤14 mm.

[0077] Figure 8 The MTF curve and MTF (Modulation Transfer Function) curve of the clustered telephoto lens of Example 2 in the telephoto state are shown. The MTF curve shows the imaging system's transmission of image details (i.e., image contrast) at different spatial frequencies. At infinity and a spatial frequency of 125 lp / mm, the OTF modulus is greater than 0.2, indicating excellent resolution. Figure 9The MTF curve of the cluster telephoto lens of Example 2 at close focus state and the MTF (Modulation Transfer Function) curve are shown. The MTF curve shows the transmission of image details (i.e. image contrast) of the imaging system at different spatial frequencies. The OTF modulus is greater than 0.1 at a close focus of 20cm and a spatial frequency of 120lp / mm, indicating good resolution. Figures 8 and 9 It can be seen that the group telephoto lens provided in Example 2 has good resolution in both the far-focus state and the near-focus state, and can achieve good imaging quality.

[0078] Example 3 The following reference Figure 10 and Figure 11 The following describes a grouped telephoto lens according to embodiment 2 of the present application. Figure 10 and Figure 11 Schematic diagrams of the front structure of the folded optical path of the group telephoto lens in the far focus state and the near focus state according to Example 3 of the present application are respectively shown.

[0079] like Figure 10 and Figure 11 As shown, the clustered telephoto lens includes a first lens group 10, a folding prism P1, a second lens group 20, and a chip imaging assembly 30. The folding prism P1 includes a light-entry side and a light-exit side, with a filter film disposed on the light-entry side and / or the light-exit side of the folding prism P1. The first lens group 10 is positioned before the light-entry side of the folding prism P1, and the second lens group 20 is positioned after the light-exit side of the folding prism P1. In other embodiments, the first lens group 10 is positioned before the light-entry side of the folding prism P1, and the second lens group 20 is positioned immediately adjacent to the light-entry side of the folding prism P1 and between the first lens group 10 and the light-entry side of the folding prism P1. The first lens group 10 and / or the second lens group 20 move along the optical axis for focusing. The first lens group 10 includes, from the object side to the image side, a first lens L1, a second lens L1, and a third lens L3. The second lens group 20 includes a fourth lens L4. An aperture stop STO may be disposed on the object-side surface of the first lens L1.

[0080] Please also refer to the following Figure 10 、 Figure 11As shown in Table 5, the first lens L1 has positive optical power, and its object side surface is convex, and its image side surface is convex. The second lens L2 has negative optical power, its object side surface is concave, and its image side surface is convex. The third lens L3 has positive optical power, its object side surface is concave, and its image side surface is convex. The return prism P1 has a light input side and a light output side. The fourth lens L4 has positive optical power, its object side surface is convex, and its image side surface is concave. The light from the object first passes through the first lens group 10, specifically the aperture STO, the first lens L1, the second lens L2 and the third lens L3; then enters the return prism P1 through the light input side, is reflected at least twice inside the return prism P1, and is emitted through the light output side; then passes through the second lens group 20, that is, the fourth lens L4, and is projected onto the imaging surface IMG of the chip imaging component 30.

[0081] Table 5 shows the basic parameters of the cluster telephoto lens of Example 3, wherein the units of the curvature radius, thickness, focal length and aperture are all millimeters (mm).

[0082] Table 5:

[0083] Table 6 shows the conic coefficients and higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 of the object-side and image-side surfaces of the first to fourth lenses L1 to L4, which can be used in Example 3, when the surfaces are even-order aspheric surfaces. The surface shape of each even-order aspheric surface can be defined by formula (1) given in Example 1.

[0084] Table 6:

[0085] In Example 3, the cluster telephoto lens has a system focal length f' of 13.88 mm, an aperture value F# of 2.65, an image circle diameter of 8.31 mm, and an operating wavelength range of 420-380 nm. In the telephoto state, the distance H8a along the optical axis between the third lens element L3 (i.e., the lens element in the first lens group 10 closest to the folding prism P1) and the folding prism P1; in the near-focus state, the distance H8b along the optical axis between the third lens element L3 (i.e., the lens element in the first lens group 10 closest to the folding prism P1) and the folding prism P1; the near-focus object distance H0 (e.g., 20 cm); and the system focal length f' of the cluster telephoto lens are related by the equation ABS(H8a-H8b) / (f'*H0 / (H0-f')-f')=0.95, satisfying ABS(H8a-H8b) / (f'*H0 / (H0-f')-f')≤1. The central thickness H11 of the fourth lens element L4 and the equivalent thickness H9 of the folding prism P1 are related by the equation H11 / H9=0.035, satisfying 0.01≤H11 / H9≤0.1. The equivalent thickness H9 of the folding prism P1 and the system focal length f' of the cluster telephoto lens are related by the equation f' / H9=0.962, satisfying 0.25≤f' / H9≤1.2. The focal length f1 of the first lens element L1 and the system focal length f' of the cluster telephoto lens are related by the equation f1 / f'=0.563, satisfying 0.2≤f1 / f'≤1. The focal length f4 of the fourth lens element L4 and the system focal length f' of the cluster telephoto lens are related by the equation f4 / f'=-1.841, satisfying -5≤f4 / f'≤0. The Abbe number AB1 of first lens L1 and its refractive index N1 are related by the equation AB1 / N1=0.028, satisfying 0.01≤AB1 / N1≤0.05. The radius of curvature C3 of the object-side surface of the lens closest to the object in first lens group 10 and the radius of curvature C12 of the object-side surface of fourth lens L4 are related by the equation C3 / C12=1.360, satisfying 0.5≤C3 / C12≤1.8. The refractive index Np of folding prism P1 is 1.720, satisfying 1≤Np≤1.9. The distance H12 from the object-side surface of the lens closest to imaging plane IMG in second lens group 20 to imaging plane IMG is 1.391 mm, satisfying 0.25 mm≤H12≤14 mm.

[0086] Figure 12 The MTF curve and MTF (Modulation Transfer Function) curve of the clustered telephoto lens of Example 3 in the telephoto state are shown. The MTF curve shows the imaging system's transmission of image details (i.e., image contrast) at different spatial frequencies. At infinity and a spatial frequency of 125 lp / mm, the OTF modulus is greater than 0.2, indicating excellent resolution. Figure 13The MTF curve of the cluster telephoto lens of Example 3 at close focus is shown, as well as the MTF (Modulation Transfer Function) curve. The MTF curve shows the transmission of image details (i.e., image contrast) of the imaging system at different spatial frequencies. The OTF modulus is greater than 0.1 at a close focus of 20 cm and a spatial frequency of 120 lp / mm, indicating excellent resolution. Figures 12 to 13 It can be seen that the group telephoto lens provided in Example 3 has good resolution in both the far-focus state and the near-focus state, and can achieve good imaging quality.

[0087] In summary, Example 1, Example 2, and Example 3 respectively satisfy the relationships shown in Table 7.

[0088] Table 7:

[0089] The above description is merely a preferred embodiment of the present application and an illustration 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 the technical solutions formed by the specific combination of the above-mentioned technical features, but also encompasses other technical solutions formed by any combination of the above-mentioned technical features or their equivalents without departing from the inventive concept. For example, a technical solution formed by replacing the above-mentioned features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. A group telephoto lens, characterized in that: It includes a first lens group, a folding prism, a second lens group and a chip imaging component; The folding prism comprises a light-incoming side and a light-outgoing side, and a filter film is provided on the light-incoming side and / or the light-outgoing side of the folding prism; The first lens group includes at least three lenses, which are arranged in front of the light-entering side of the return prism; the second lens group includes at least one lens, which is arranged behind the light-exiting side of the return prism, or is set adjacent to the light-entering side of the return prism, and is located between the first lens group and the light-entering surface of the return prism; the first lens group and / or the second lens group moves along the optical axis to focus.

2. The group telephoto lens according to claim 1, wherein: If the first lens group is arranged before the light-incoming side of the folding prism, and the second lens group is arranged after the light-outgoing side of the folding prism, the distance M1 from the bottom of the folding prism to the axial outermost point of the object-side surface of the lens of the first lens group closest to the object side, and the distance M2 from the bottom of the folding prism to the bottom surface of the circuit board where the chip imaging component is located, satisfy: M2+0.5<M1<M2+4.

3. The group telephoto lens according to claim 1, wherein: If the first lens group is arranged before the light-incoming side of the folding prism, and the second lens group is arranged after the light-outgoing side of the folding prism, the distance M1 from the bottom of the folding prism to the axial outermost point of the object-side surface of the lens of the first lens group closest to the object side, and the distance M2 from the bottom of the folding prism to the bottom surface of the circuit board where the chip imaging component is located, and the total optical length M3 of the group telephoto lens satisfy: M1+M2<M3-2.

4. The group telephoto lens according to claim 1, wherein: A distance M4 between the intersection of the zero-field chief ray at the second reflecting surface of the folding prism and the incident optical axis satisfies: M4 ≥ 3.5 mm.

5. The group telephoto lens according to claim 1, wherein: If the first lens group is arranged before the light-entering side of the folding prism, and the second lens group is arranged after the light-exiting side of the folding prism, in the far-focus state, the distance H8a along the optical axis between the lens of the first lens group closest to the folding prism and the folding prism, and in the near-focus state, the distance H8b along the optical axis between the lens of the first lens group closest to the folding prism and the folding prism, the near-focus object distance H0, and the system focal length f' of the grouped telephoto lens satisfy: ABS(H8a-H8b) / (f'*H0 / (H0-f')-f')≤1.

6. The group telephoto lens according to claim 1, wherein: The optical power EFX1 of the first lens group and the system focal length f' of the group telephoto lens satisfy: EFX1 / f'<1.

7. The group telephoto lens according to claim 1, wherein: The second lens group includes a fourth lens, and an equivalent thickness H9 of the folding prism and a center thickness H11 of the fourth lens satisfy the following conditions: 0.01≤H11 / H9≤0.

1.

8. The group telephoto lens according to claim 1, wherein: The equivalent thickness H9 of the folding prism and the system focal length f' of the group telephoto lens satisfy the following: 0.25≤f' / H9≤1.

2.

9. The group telephoto lens according to claim 1, wherein: The second lens group includes a fourth lens, and a focal length f4 of the fourth lens and a system focal length f' of the group telephoto lens satisfy: -5≤f4 / f'≤0.

10. The group telephoto lens according to claim 1, wherein: The object-side surface of the lens closest to the object in the first lens group has a curvature radius C3, the second lens group includes a fourth lens, and the object-side surface of the fourth lens has a curvature radius C12 that satisfies: 0.5≤C3 / C12≤1.8.

Images