Long-focus lens and electronic device

Abstract

The application discloses a long-focus lens, which comprises, in sequence from the object side to the image side, a first lens assembly, a first prism, a second lens assembly, a second prism and an image sensor; the first lens assembly comprises at least a first lens; the first prism comprises a first working surface facing the first lens and a second working surface facing the second lens assembly; the second prism comprises a third working surface facing the second lens assembly, a fifth working surface facing the image sensor and a fourth working surface for performing second reflection on incident light from the fifth working surface; the imaging surface of the image sensor is arranged relative to the fifth working surface; and the thickness OAL1 of the second lens assembly and the equivalent thickness H15 of the second prism satisfy the condition: 0.25<=OAL1 / H15<=0.85. The long-focus lens disclosed by the application effectively reduces the overall height and is beneficial to the miniaturization of the lens. The application further discloses an electronic device.

Description

Technical Field

[0001] This invention relates to the field of optical imaging technology, and in particular to a telephoto lens and an electronic device. Background Technology

[0002] As various electronic products become increasingly multifunctional, camera functionality has become a standard feature in smartphones, tablets, and other electronic products.

[0003] However, as users' demands for image quality continue to increase, telephoto lenses, due to their longer back focal length, generally have the problem of being too tall and protruding from the camera body, which affects the overall appearance and aesthetics of the camera. Summary of the Invention

[0004] In view of the above problems, the purpose of this invention is to provide a telephoto lens that effectively reduces the overall height and facilitates lens miniaturization.

[0005] This invention provides a telephoto lens, comprising, from the object side to the image side, a first lens assembly, a first prism, a second lens assembly, a second prism, and an image sensor. The first lens assembly includes at least a first lens. The first prism includes a first working surface facing the first lens and a second working surface facing the second lens assembly. The second prism includes a third working surface facing the second lens assembly, a fifth working surface facing the image sensor, and a fourth working surface for reflecting incident light from the fifth working surface a second time. The imaging surface of the image sensor is disposed relative to the fifth working surface. The fifth working surface is used to reflect incident light from the first working surface a first time and to exit incident light from the fourth working surface onto the imaging surface. The thickness OAL1 of the second lens assembly and the equivalent thickness H15 of the second prism satisfy: 0.25≤OAL1 / H15≤0.85.

[0006] Optionally, the second lens assembly includes a second lens, a third lens, a fourth lens, and a fifth lens arranged in sequence, wherein the first lens, the second lens, and the fourth lens have positive optical power, and the third lens and the fifth lens have negative optical power.

[0007] Optionally, the focal length f1 of the first lens and the focal length f of the telephoto lens satisfy: 1≤f1 / f≤5.

[0008] Optionally, the focal length f2 of the second lens and the focal length f of the telephoto lens satisfy: 0.2≤f2 / f≤0.8.

[0009] Optionally, the focal length f5 of the fifth lens and the focal length f of the telephoto lens satisfy: 0.15≤abs(f5) / f≤0.75.

[0010] Optionally, the equivalent thickness H4 of the first prism, the focal length f of the telephoto lens, and the aperture F# of the telephoto lens satisfy: 8≤|H4-f| / F#≤21.

[0011] Optionally, the equivalent thickness H15 of the second prism and the focal length f of the telephoto lens satisfy: 0.25≤H15 / f≤1.

[0012] Optionally, the radius of curvature r1 of the object side surface of the first lens and the radius of curvature r2 of the object side surface of the second lens satisfy: 1≤r1 / r2≤3.

[0013] Optionally, the equivalent thickness H2 of the first lens and the equivalent thickness H4 of the first prism satisfy: 0.1≤H2 / H4≤1.

[0014] Optionally, the focal length f of the telephoto lens and the aperture F# of the telephoto lens satisfy: 4≤f / F#≤10.

[0015] Optionally, the distance OAL2 from the fifth working surface to the imaging surface and the aperture F# of the telephoto lens satisfy: 0.3≤OAL2 / F#≤0.65.

[0016] Optionally, the focal length f1 of the first lens, the focal length f2 of the second lens, and the focal length f5 of the fifth lens satisfy: 3≤(f1+f2) / abs(f5)≤11.

[0017] Optionally, the Abbe number Ab1 of the first lens satisfies: 55 ≤ Ab1 ≤ 85.

[0018] Optionally, the telephoto lens further includes an aperture stop, which is disposed on the image side of the first prism.

[0019] Optionally, the telephoto lens further includes a filter for correcting color deviation and / or a protective glass for protecting the photosensitive element located on the imaging surface, the filter being disposed between the fifth working surface and the imaging surface.

[0020] Optionally, the third working surface is perpendicular to the fourth working surface, and the included angle α between the fourth working surface and the fifth working surface satisfies: 27°≤α≤33°, and the included angle β between the third working surface and the fifth working surface satisfies: 54°≤β≤66°.

[0021] Optionally, the first prism further includes a sixth working surface, which is used to reflect incident light from the first working surface to the second working surface.

[0022] The present invention also provides an electronic device including the telephoto lens described above.

[0023] The telephoto lens provided by this invention, by controlling the ratio between the thickness of the second lens assembly and the equivalent thickness of the second prism within a reasonable range, is beneficial to shortening the length of the second lens assembly, reducing the overall volume, facilitating lens miniaturization, and effectively reducing the overall height. At the same time, by reflecting light twice internally through the second prism before it is emitted to the imaging surface, and folding the lens's back focal length twice inside the second prism, the overall height can be further reduced and the image quality improved, thereby enhancing the user experience. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0025] Figure 1 A schematic diagram of the structure of a telephoto lens according to an embodiment of this application is shown.

[0026] Figure 2 A schematic diagram of the telephoto lens of Embodiment 1 of this application is shown.

[0027] Figures 3 to 5 The MTF curve, aperture fan diagram, relative illumination and Y field of view diagram of the telephoto lens of Example 1 are shown respectively.

[0028] Figure 6 A schematic diagram of the telephoto lens of Embodiment 2 of this application is shown.

[0029] Figures 7 to 9 The MTF curve, fan diagram, relative illumination and Y field of view diagram of the telephoto lens of Example 2 are shown respectively.

[0030] Figure 10 A schematic diagram of the telephoto lens of Embodiment 3 of this application is shown.

[0031] Figures 11 to 13 The MTF curve, fan diagram, relative illumination and Y field of view diagram of the telephoto lens of Example 3 are shown respectively. Detailed Implementation

[0032] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of preferred embodiments with reference to the accompanying drawings. Through the description of the specific embodiments, a more in-depth and specific understanding can be gained of the technical means and effects adopted by the present invention to achieve its intended purpose. However, the accompanying drawings are for reference and illustration only 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 clarity, the various parts in the drawings are not necessarily drawn strictly to scale.

[0033] It is important to understand that the terms "first," "second," "third," "fourth," etc., are used merely to distinguish elements or circuits with similar properties, and do not indicate or imply relative importance or a specific order. The terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, which includes not only the listed elements but also other elements not expressly listed.

[0034] 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 only. 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 drawn strictly to scale.

[0035] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the subject is called the object-side surface of the lens, and the surface of each lens closest to the imaging plane (IMG) is called the image-side surface of the lens.

[0036] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This 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] Figure 1 A schematic diagram of the structure of a telephoto lens according to an embodiment of this application is shown. Figure 1As shown, a telephoto lens, from the object side to the image side, includes a first lens assembly 10, a first prism P1, a second lens assembly 20, a second prism P2, and an image sensor. The first lens assembly 10 includes at least a first lens L1. The first prism P1 includes a first working surface 110 facing the first lens L1 and a second working surface 120 facing the second lens assembly 20. The second prism P2 includes a third working surface 210 facing the second lens assembly 20, a fifth working surface 230 facing the image sensor, and a fourth working surface 220 for reflecting incident light from the fifth working surface 230 a second time. The image sensor's imaging surface IMG is positioned relative to the fifth working surface 230. The fifth working surface 230 is used to reflect incident light from the first working surface 110 a first time and to exit incident light from the fourth working surface 220 onto the imaging surface IMG. The thickness OAL1 of the second lens assembly 20 and the equivalent thickness H15 of the second prism P2 satisfy: 0.25≤OAL1 / H15≤0.85.

[0039] When the telephoto lens of this application is in use, the incident light sequentially passes through the first lens L1 and the first working surface 110 and enters the first prism P1, then exits through the second working surface 120 and passes through the second lens assembly 20 and the third working surface 210 to enter the second prism P2, is reflected for the first time by the fifth working surface 230 and then reflected to the fourth working surface 220, is reflected for the second time by the fourth working surface 220 and then reflected to the fifth working surface 230, and exits through the fifth working surface 230 to the imaging surface IMG.

[0040] By controlling the ratio between the thickness OAL1 of the second lens assembly 20 and the equivalent thickness H15 of the second prism P2 within a reasonable range, it is beneficial to shorten the length of the second lens assembly 20, thereby reducing the overall volume, which is conducive to lens miniaturization and effectively reducing the overall height. Simultaneously, by having the light reflected twice internally by the second prism P2 before exiting to the imaging surface IMG, the original direction of the light can be changed without occupying a large space, and only a short optical path is needed to reach the imaging surface IMG. This correspondingly shortens the lens's back focal length. Folding the lens's back focal length twice inside the second prism P2 further reduces the overall height and improves image quality, thereby enhancing the user experience.

[0041] In an exemplary embodiment, the second lens assembly 20 includes a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5 arranged in sequence. The first lens L1, the second lens L2, and the fourth lens L4 have positive optical power, while the third lens L3 and the fifth lens L5 have negative optical power.

[0042] Specifically, the second working surface 120 is positioned toward the second lens L2, and the third working surface 210 is positioned toward the fifth lens L5. The thickness OAL1 of the second lens assembly 20 is the thickness OAL1 between the object side of the second lens L2 and the image side of the fifth lens L5. The thickness OAL1 between the object side of the second lens L2 and the image side of the fifth lens L5, and the equivalent thickness H15 of the second prism P2 satisfy: 0.25≤OAL1 / H15≤0.85.

[0043] When the telephoto lens of this application is in use, the incident light passes sequentially through the first lens L1 and the first working surface 110 into the first prism P1, then exits through the second working surface 120 and passes sequentially through the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5 and the third working surface 210 into the second prism P2. After the first reflection by the fifth working surface 230, it is reflected to the fourth working surface 220, then reflected a second time by the fourth working surface 220, and finally exits through the fifth working surface 230 to the imaging surface IMG.

[0044] Specifically, the first lens L1 has positive optical power and is the lens closest to the object side in the first lens assembly 10. The first lens L1 plays the main role in converging light in the entire optical system. The first prism P1 can correct the propagation path of the incident light by changing the position of the first lens L1 in the first lens assembly 10 through the first working surface 110 and the second working surface 120. This allows the light emitted from the first prism P1 to reach the second lens L2 after a shorter optical path, thereby shortening the back focal length of the lens. Furthermore, by combining the positive and negative focal powers of multiple lenses, various aberrations can be balanced to obtain a clear image.

[0045] Based on the optical power distribution of the first lens L1 to the fifth lens L5, and by reasonably allocating the optical power, spacing and refractive index of each lens, as well as the angle and thickness of the first prism P1 and the second prism P2, and compressing the height of the first lens assembly 10 and the second lens assembly 20 while satisfying the focal length, the effect of a large target surface, a large aperture and a short optical length can be achieved, effectively reducing the overall height and making the lens miniaturized.

[0046] In an exemplary embodiment, the focal length f1 of the first lens L1 and the focal length f of the telephoto lens satisfy: 1≤f1 / f≤5. By controlling the ratio of the focal length f1 of the first lens L1 to the focal length f of the telephoto lens within a suitable range, it is beneficial to reduce the sensitivity of the first lens L1 and improve the image quality.

[0047] In an exemplary embodiment, the focal length f2 of the second lens L2 and the focal length f of the telephoto lens satisfy: 0.2≤f2 / f≤0.8. By controlling the ratio of the focal length f2 of the second lens L2 to the focal length f of the telephoto lens, it is beneficial to converge the light and obtain the desired focal length.

[0048] In an exemplary embodiment, the focal length f5 of the fifth lens L5 and the focal length f of the telephoto lens satisfy: 0.15≤abs(f5) / f≤0.75. By controlling the absolute value of the focal length f5 of the fifth lens L5 and the ratio of the focal length f of the telephoto lens, it is beneficial to correct distortion and field curvature.

[0049] In an exemplary embodiment, the equivalent thickness H4 of the first prism P1, the focal length f of the telephoto lens, and the aperture F# of the telephoto lens satisfy: 8≤|H4-f| / F#≤21. By controlling the ratio of the absolute value of the difference between the equivalent thickness H4 of the first prism P1 and the focal length f of the telephoto lens to the aperture F# of the telephoto lens, light leakage is avoided, which would cause the actual aperture to fail to meet the requirements.

[0050] In an exemplary embodiment, the equivalent thickness H15 of the second prism P2 and the focal length f of the telephoto lens satisfy: 0.25≤H15 / f≤1. By controlling the ratio of the equivalent thickness H15 of the second prism P2 to the focal length f of the telephoto lens within a reasonable range, the volume of the second prism P2 can be controlled, which is beneficial to the miniaturization of the lens.

[0051] In an exemplary embodiment, the radius of curvature r1 of the object side surface of the first lens L1 and the radius of curvature r2 of the object side surface of the second lens L2 satisfy: 1≤r1 / r2≤3. By controlling the ratio of the radius of curvature r1 of the object side surface of the first lens L1 and the radius of curvature r2 of the object side surface of the second lens L2 to be within a reasonable range, it is beneficial to control the light path of the first lens L1 and the second lens L2 and reduce spherical aberration and coma.

[0052] In an exemplary embodiment, the equivalent thickness H2 of the first lens L1 and the equivalent thickness H4 of the first prism P1 satisfy: 0.1≤H2 / H4≤1. By controlling the ratio of the equivalent thickness H2 of the first lens L1 to the equivalent thickness H4 of the first prism P1 within a reasonable range, the first lens L1 is controlled to have a certain equivalent thickness, thereby ensuring the lens strength of the first lens L1.

[0053] In an exemplary embodiment, the focal length f and the aperture F# of the telephoto lens satisfy: 4≤f / F#≤10. By controlling the ratio of the focal length f and the aperture F# of the telephoto lens within a reasonable range, the aperture can be controlled, which is beneficial for correcting coma.

[0054] In an exemplary embodiment, the distance OAL2 from the fifth working surface 230 to the imaging surface IMG and the aperture F# of the telephoto lens satisfy: 0.3≤OAL2 / F#≤0.65. By controlling the ratio of the distance OAL2 from the fifth working surface 230 to the imaging surface IMG and the aperture F# of the telephoto lens to be within a reasonable range, it is beneficial to avoid dirty imaging and improve imaging quality.

[0055] In an exemplary embodiment, the focal length f1 of the first lens L1, the focal length f2 of the second lens L2, and the focal length f5 of the fifth lens L5 satisfy: 3≤(f1+f2) / abs(f5)≤11. By controlling the ratio of the absolute value of the sum of the focal length f1 of the first lens L1 and the focal length f2 of the second lens L2 to the focal length f5 of the fifth lens L5 to be within a reasonable range, the focal length of each lens can be controlled within a reasonable range, which is beneficial for controlling spherical aberration and achieving a large aperture.

[0056] In an exemplary embodiment, the Abbe number Ab1 of the first lens L1 satisfies: 55≤Ab1≤85. By controlling the Abbe number Ab1 of the first lens L1 within a reasonable range, it is beneficial to optimize chromatic aberration.

[0057] In an exemplary embodiment, the telephoto lens also includes an aperture stop STO, which is located on the image side of the first prism P1. This helps to reduce the effective aperture of the second lens assembly 20, thereby reducing the overall height.

[0058] In an exemplary embodiment, the telephoto lens also includes a filter IR for correcting color deviation and / or a protective glass for protecting the photosensitive element located on the imaging surface IMG. The filter IR is disposed between the fifth working surface 230 and the imaging surface IMG, which is beneficial for correcting aberrations generated by the imaging system.

[0059] In an exemplary embodiment, the third working surface 210 is perpendicular to the fourth working surface 220. The included angle α between the fourth working surface 220 and the fifth working surface 230 satisfies: 27°≤α≤33°, and the included angle β between the third working surface 210 and the fifth working surface 230 satisfies: 54°≤β≤66°. The third working surface 210 is connected to the fifth working surface 230, and the fourth working surface 220 is connected to the fifth working surface 230. Specifically, the imaging surface IMG is tilted relative to the fourth working surface 220 and closer to the third working surface 210. By controlling the included angle α between the fourth working surface 220 and the fifth working surface 230 and the included angle β between the third working surface 210 and the fifth working surface 230, the fourth working surface 220 and the fifth working surface 230 can be used for internal double reflection of light, and the camera height can be significantly reduced. At the same time, because the imaging surface IMG is set relative to the fifth working surface 230, the imaging surface IMG is tilted, and the image sensor is also tilted, further reducing the overall height.

[0060] In an exemplary embodiment, the first prism P1 further includes a sixth working surface 130, which is used to reflect incident light from the first working surface 110 to the second working surface 120.

[0061] The incident light rays pass through the first lens L1 and the first working surface 110 in sequence and enter the first prism P1. They are then reflected by the sixth working surface 130 to the second working surface 120 and exit through the second working surface 120.

[0062] Specifically, the first prism P1 is an isosceles right-angle prism, the first working surface 110 is perpendicular to the second working surface 120, the first working surface 110 is connected to the sixth working surface 130, the second working surface 120 is connected to the sixth working surface 130, and the sixth working surface 130 reflects the incident light entering the first prism P1 to deflect the light, thereby correcting the propagation path of the incident light and further reducing the height of the camera.

[0063] In an exemplary embodiment, the first prism P1 is a flat glass plate, and the first working surface 110 and the second working surface 120 are arranged in parallel. The incident light rays pass through the first lens L1 and the first working surface 110 in sequence and enter the first prism P1, and then exit through the second working surface 120. This helps to correct the propagation path of the incident light rays, so that the incident light rays can reach the second lens L2 after exiting the first prism P1 with a shorter optical path, thereby shortening the back focal length of the lens and reducing the overall height.

[0064] In an exemplary embodiment, the fourth working surface 220 may be coated with a reflective film. This ensures that incident light is completely reflected when reflected by the fourth working surface 220, reducing the risk of incident light being refracted through the second prism P2 during reflection at the fourth working surface 220. It is understood that a portion of the fifth working surface 230 may also be coated with a reflective film. The sixth working surface 130 may be coated with a reflective film to ensure complete reflection of light, reducing the risk of incident light being refracted through the first prism P1 during reflection at the sixth working surface 130.

[0065] Based on the same inventive concept, this application also provides an electronic device, including the aforementioned telephoto lens. The electronic device includes, but is not limited to, smartphones, tablets, laptops, gimbal cameras, surveillance cameras, and other imaging devices. Implementations of this electronic device can be found in the embodiments of the telephoto lens; repeated details will not be elaborated further.

[0066] However, those skilled in the art will understand that the number of lenses constituting the optical imaging lens can be changed without departing from the technical solutions claimed in this application to obtain the various results and advantages described in this specification. For example, although the first lens assembly 10 is described in the embodiment as having one lens, it is not limited to including one lens. If desired, the first lens assembly 10 may also include other numbers of lenses; although the second lens assembly 20 is described in the embodiment as having four lenses, it is not limited to including four lenses. If desired, the second lens assembly 20 may also include other numbers of lenses.

[0067] The following describes in further detail, with reference to the accompanying drawings, specific embodiments of the telephoto lens applicable to the above-described embodiments.

[0068] Example 1

[0069] The following is for reference Figure 2 A telephoto lens according to Embodiment 1 of this application is described.

[0070] The telephoto lens of Embodiment 1, from the object side to the image side, includes a first lens assembly 10, a first prism P1, a second lens assembly 20, a second prism P2, and an image sensor in sequence. The first lens assembly 10 includes a first lens L1, and the second lens assembly 20 includes a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5 arranged in sequence. The first prism P1 includes a first working surface 110 facing the first lens L1 and a second working surface 120 facing the second lens L2. The second prism P2 includes a third working surface 210 facing the fifth lens L5 and a second working surface 120 facing the image sensor. The image sensor comprises a fifth working surface 230 and a fourth working surface 220 for a second reflection of incident light from the fifth working surface 230. The imaging surface IMG of the image sensor is positioned relative to the fifth working surface 230. The fifth working surface 230 is used for a first reflection of incident light from the first working surface 110 and for exiting incident light from the fourth working surface 220 onto the imaging surface IMG. The thickness OAL1 between the object side of the second lens L2 and the image side of the fifth lens L5, and the equivalent thickness H15 of the second prism P2, satisfy: 0.25 ≤ OAL1 / H15 ≤ 0.85. The first lens L1, the second lens L2, and the fourth lens L4 have positive optical power, and the third lens L3 and the fifth lens L5 have negative optical power. The aperture stop STO is positioned on the image side of the first prism P1. The filter IR is positioned between the fifth working surface 230 and the imaging surface IMG. The third working surface 210 is perpendicular to the fourth working surface 220. The third working surface 210 is connected to the fifth working surface 230, and the fourth working surface 220 is connected to the fifth working surface 230. The included angle α between the fourth working surface 220 and the fifth working surface 230 is 30°, and the included angle β between the third working surface 210 and the fifth working surface 230 is 60°. The first prism P1 is a flat glass, and the first working surface 110 and the second working surface 120 are arranged in parallel.

[0071] The first lens L1 has positive optical power, with a convex object-side surface and a concave image-side surface. The second lens L2 has positive optical power, with a convex object-side surface and a concave image-side surface. The third lens L3 has negative optical power, with a concave object-side surface and a concave image-side surface. The fourth lens L4 has positive optical power, with a convex object-side surface and a convex image-side surface. The fifth lens L5 has negative optical power, with a concave object-side surface and a convex image-side surface. The filter IR has both an object-side surface and an image-side surface. The incident light rays pass sequentially through the first lens L1 and the first working surface 110 into the first prism P1, then exit through the second working surface 120 and pass sequentially through the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5 and the third working surface 210 into the second prism P2. After the first reflection by the fifth working surface 230, the light rays are reflected to the fourth working surface 220, then reflected a second time by the fourth working surface 220, and finally exit through the fifth working surface 230 and pass through the object side and image side of the filter IR, and finally form an image on the imaging surface IMG.

[0072] Table 1 shows the basic parameters of the telephoto lens in Example 1, where the units for radius of curvature, thickness, and focal length are all millimeters (mm).

[0073] Table 1:

[0074]

[0075] Wherein, L1-R1 represents the object-side surface of the first lens L1, L1-R2 represents the image-side surface of the first lens L1, P1-R1 represents the object-side surface of the first prism P1 (i.e., the first working surface 110), P1-R2 represents the image-side surface of the first prism P1 (i.e., the second working surface 120), L2-R1 represents the object-side surface of the second lens L2, 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. On the side, L4-R1 represents the object side of the fourth lens L4, L4-R2 represents the image side of the fourth lens L4, L5-R1 represents the object side of the fifth lens L5, L5-R2 represents the image side of the fifth lens L5, P2-R1 represents the object side of the second prism P2, i.e., the third working surface 210, P2-R2 represents the image side of the second prism P2, i.e., the fifth working surface 230, IR-R1 represents the object side of the filter IR, and IR-R2 represents the image side of the filter IR.

[0076] In Example 1, the object-side surface and image-side surface of any one of the second lens L2 to the fifth lens L5 are both even-order aspherical surfaces. The surface shape of each aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0077] (1)

[0078] Where Z represents the height along the optical axis, c is the reciprocal of the surface radius, k is the conic coefficient, and r is the aperture along the radial direction; α represents the aspherical coefficient, α1 represents the aspherical coefficient A2, α2 represents the aspherical coefficient A4, and so on. Table 2 gives the higher-order coefficients A2, A4, A6, A8, A10, A12, A14, and A16 that can be used for each aspherical mirror in Example 1.

[0079] Table 2:

[0080]

[0081] In Embodiment 1, the optical power distribution of the first lens L1 to the fifth lens L5, the optical power, spacing and refractive index of each lens, and the angle and thickness of the first prism P1 and the second prism P2 are reasonably allocated and set according to the table above. While satisfying the focal length, the height of the first lens assembly 10 and the second lens assembly 20 is compressed, which can achieve the effect of large target surface, large aperture and short optical length, effectively reducing the overall height and making the lens miniaturized. The telephoto lens has a field of view of 33°, an aperture value of 2.45, a focal length f of 15.27mm, a working wavelength of 420~680nm, and an imaging circle diameter of 9.6mm. The relationship between the focal length f1 of the first lens L1 and the focal length f of the telephoto lens is f1 / f = 3.93; the relationship between the focal length f2 of the second lens L2 and the focal length f of the telephoto lens is f2 / f = 0.53; the relationship between the focal length f5 of the fifth lens L5 and the focal length f of the telephoto lens is abs(f5) / f = 0.60; the relationship between the equivalent thickness H4 of the first prism P1, the focal length f of the telephoto lens, and the aperture F# of the telephoto lens is |H4-f| / F# = 11.23; the relationship between the equivalent thickness H15 of the second prism P2 and the focal length f of the telephoto lens is H15 / f = 0.69; the relationship between the thickness OAL1 between the object side of the second lens L2 and the image side of the fifth lens L5 and the equivalent thickness H15 of the second prism P2 is OAL1 / H15. =0.52; The relationship between the radius of curvature r1 of the object side surface of the first lens L1 and the radius of curvature r2 of the object side surface of the second lens L2 is r1 / r2=2.20; The relationship between the equivalent thickness H2 of the first lens L1 and the equivalent thickness H4 of the first prism P1 is H2 / H4=0.30; The relationship between the focal length f of the telephoto lens and the aperture F# of the telephoto lens is f / F#=6.23; The relationship between the distance OAL2 from the fifth working surface 230 to the imaging surface IMG and the aperture F# of the telephoto lens is OAL2 / F#=0.41; The relationship between the focal length f1 of the first lens L1, the focal length f2 of the second lens L2 and the focal length f5 of the fifth lens L5 is (f1+f2) / abs(f5)=7.5; The Abbe number Ab1 of the first lens L1 is 64.2.

[0082] Figure 3 The MTF curve of the telephoto lens in Example 1 is shown. The MTF (Modulation Transfer Function) curve shows the transmission of image details (i.e. image contrast) at different spatial frequencies by the imaging system. At a spatial frequency of 90 lp / mm, the MTF value is greater than 0.5, indicating good resolution and good imaging effect. Figure 4 The optical fan diagram of the telephoto lens of Example 1 is shown. The optical fan diagram typically shows the cross-section of the light beam at different positions, as well as the path and variation of its propagation in the optical system. It is a comprehensive evaluation diagram of various aberrations, with a scale of ±20µm, that is, the scale range in the horizontal and vertical directions is ±20µm, and various aberrations are well corrected. Figure 5 The diagram shows the relative illuminance and Y-field angle of the telephoto lens in Example 1. The relative illuminance is greater than 0.6, and the illuminance is uniform. According to... Figures 3 to 5 As can be seen, the telephoto lens given in Example 1 has well-corrected aberrations, uniform illumination, and good resolution, and can achieve good image quality.

[0083] Example 2

[0084] The following is for reference Figure 6 This application describes a telephoto lens according to Embodiment 2. For the sake of brevity, descriptions similar to those in Embodiment 1 are omitted in this embodiment.

[0085] The telephoto lens of Embodiment 2, from the object side to the image side, includes a first lens assembly 10, a first prism P1, a second lens assembly 20, a second prism P2, and an image sensor. The first lens assembly 10 includes a first lens L1, and the second lens assembly 20 includes a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5 arranged in sequence. The first prism P1 includes a first working surface 110 facing the first lens L1 and a second working surface 120 facing the second lens L2. The second prism P2 includes a third working surface 210 facing the fifth lens L5 and a second working surface 120 facing the image sensor. The image sensor comprises a fifth working surface 230 and a fourth working surface 220 for a second reflection of incident light from the fifth working surface 230. The imaging surface IMG of the image sensor is positioned relative to the fifth working surface 230. The fifth working surface 230 is used for a first reflection of incident light from the first working surface 110 and for exiting incident light from the fourth working surface 220 onto the imaging surface IMG. The thickness OAL1 between the object side of the second lens L2 and the image side of the fifth lens L5, and the equivalent thickness H15 of the second prism P2, satisfy: 0.25 ≤ OAL1 / H15 ≤ 0.85. The first lens L1, the second lens L2, and the fourth lens L4 have positive optical power, and the third lens L3 and the fifth lens L5 have negative optical power. The aperture stop STO is positioned on the image side of the first prism P1. The filter IR is positioned between the fifth working surface 230 and the imaging surface IMG. The third working surface 210 is perpendicular to the fourth working surface 220. The third working surface 210 is connected to the fifth working surface 230, and the fourth working surface 220 is connected to the fifth working surface 230. The included angle α between the fourth working surface 220 and the fifth working surface 230 is 30°, and the included angle β between the third working surface 210 and the fifth working surface 230 is 60°. The first prism P1 is a flat glass, and the first working surface 110 and the second working surface 120 are arranged in parallel.

[0086] The first lens L1 has positive optical power, with a convex object-side surface and a concave image-side surface. The second lens L2 has positive optical power, with a convex object-side surface and a concave image-side surface. The third lens L3 has negative optical power, with a concave object-side surface and a concave image-side surface. The fourth lens L4 has positive optical power, with a convex object-side surface and a convex image-side surface. The fifth lens L5 has negative optical power, with a concave object-side surface and a convex image-side surface. The filter IR has both an object-side surface and an image-side surface. The incident light rays pass sequentially through the first lens L1 and the first working surface 110 into the first prism P1, then exit through the second working surface 120 and pass sequentially through the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5 and the third working surface 210 into the second prism P2. After the first reflection by the fifth working surface 230, the light rays are reflected to the fourth working surface 220, then reflected a second time by the fourth working surface 220, and finally exit through the fifth working surface 230 and pass through the object side and image side of the filter IR, and finally form an image on the imaging surface IMG.

[0087] Table 3 shows the basic parameters of the telephoto lens in Example 2, where the units for radius of curvature, thickness, and focal length are all millimeters (mm).

[0088] Table 3:

[0089]

[0090] Table 4 shows the higher-order coefficients that can be used for each aspherical mirror in Example 2, wherein each aspherical surface shape can be defined by formula (1) given in Example 1 above.

[0091] Table 4:

[0092]

[0093] In Embodiment 2, the optical power distribution of the first lens L1 to the fifth lens L5, the optical power, spacing and refractive index of each lens, and the angle and thickness of the first prism P1 and the second prism P2 are reasonably allocated and set according to the table above. While satisfying the focal length, the height of the first lens assembly 10 and the second lens assembly 20 is compressed, which can achieve the effect of large target surface, large aperture and short optical length, effectively reducing the overall height and making the lens miniaturized. The telephoto lens has a field of view of 32°, an aperture value of 2.5, a focal length f of 16.453mm, a working wavelength of 420~680nm, and an imaging circle diameter of 9.6mm. The relationship between the focal length f1 of the first lens L1 and the focal length f of the telephoto lens is f1 / f = 3.28; the relationship between the focal length f2 of the second lens L2 and the focal length f of the telephoto lens is f2 / f = 0.55; the relationship between the focal length f5 of the fifth lens L5 and the focal length f of the telephoto lens is abs(f5) / f = 0.55; the relationship between the equivalent thickness H4 of the first prism P1, the focal length f of the telephoto lens, and the aperture F# of the telephoto lens is |H4-f| / F# = 12.88; the relationship between the equivalent thickness H15 of the second prism P2 and the focal length f of the telephoto lens is H15 / f = 0.64; the relationship between the thickness OAL1 between the object side of the second lens L2 and the image side of the fifth lens L5 and the equivalent thickness H15 of the second prism P2 is OAL1 / H15. =0.57; The relationship between the radius of curvature r1 of the object side surface of the first lens L1 and the radius of curvature r2 of the object side surface of the second lens L2 is r1 / r2=1.84; The relationship between the equivalent thickness H2 of the first lens L1 and the equivalent thickness H4 of the first prism P1 is H2 / H4=0.16; The relationship between the focal length f of the telephoto lens and the aperture F# of the telephoto lens is f / F#=6.58; The relationship between the distance OAL2 from the fifth working surface 230 to the imaging surface IMG and the aperture F# of the telephoto lens is OAL2 / F#=0.40; The relationship between the focal length f1 of the first lens L1, the focal length f2 of the second lens L2 and the focal length f5 of the fifth lens L5 is (f1+f2) / abs(f5)=7.0; The Abbe number Ab1 of the first lens L1 is 68.3.

[0094] Figure 7 The MTF curve of the telephoto lens in Example 2 is shown. The MTF (Modulation Transfer Function) curve shows the transmission of image details (i.e. image contrast) at different spatial frequencies by the imaging system. At a spatial frequency of 90 lp / mm, the MTF value is greater than 0.5, indicating good resolution and good imaging effect. Figure 8The optical fan diagram of the telephoto lens of Example 2 is shown. The optical fan diagram typically shows the cross-section of the light beam at different positions, as well as the path and changes in the propagation of the beam in the optical system. It is a comprehensive evaluation diagram of various aberrations, with a scale of ±20µm, that is, the scale range in the horizontal and vertical directions is ±20µm, and various aberrations are well corrected. Figure 9 The diagram shows the relative illumination and Y-field of view of the telephoto lens in Example 2. The relative illumination is greater than 0.6, and the illumination is uniform. According to... Figures 7 to 9 It can be seen that the telephoto lens given in Example 2 has well corrected aberrations, uniform illumination and good resolution, and can achieve good image quality.

[0095] Example 3

[0096] The following is for reference Figure 10 This application describes a telephoto lens according to Embodiment 3. For the sake of brevity, descriptions similar to those in Embodiment 1 are omitted in this embodiment.

[0097] The telephoto lens of Embodiment 3, from the object side to the image side, includes a first lens assembly 10, a first prism P1, a second lens assembly 20, a second prism P2, and an image sensor in sequence. The first lens assembly 10 includes a first lens L1, and the second lens assembly 20 includes a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5 arranged in sequence. The first prism P1 includes a first working surface 110 facing the first lens L1 and a second working surface 120 facing the second lens L2. The second prism P2 includes a third working surface 210 facing the fifth lens L5 and a second working surface 120 facing the image sensor. The image sensor comprises a fifth working surface 230 and a fourth working surface 220 for a second reflection of incident light from the fifth working surface 230. The imaging surface IMG of the image sensor is positioned relative to the fifth working surface 230. The fifth working surface 230 is used for a first reflection of incident light from the first working surface 110 and for exiting incident light from the fourth working surface 220 onto the imaging surface IMG. The thickness OAL1 between the object side of the second lens L2 and the image side of the fifth lens L5, and the equivalent thickness H15 of the second prism P2, satisfy: 0.25 ≤ OAL1 / H15 ≤ 0.85. The first lens L1, the second lens L2, and the fourth lens L4 have positive optical power, and the third lens L3 and the fifth lens L5 have negative optical power. The aperture stop STO is positioned on the image side of the first prism P1. The filter IR is positioned between the fifth working surface 230 and the imaging surface IMG. The third working surface 210 is perpendicular to the fourth working surface 220. The third working surface 210 is connected to the fifth working surface 230, and the fourth working surface 220 is connected to the fifth working surface 230. The included angle α between the fourth working surface 220 and the fifth working surface 230 is 30°, and the included angle β between the third working surface 210 and the fifth working surface 230 is 60°. The first prism P1 is a flat glass, and the first working surface 110 and the second working surface 120 are arranged in parallel.

[0098] The first lens L1 has positive optical power, with a convex object-side surface and a concave image-side surface. The second lens L2 has positive optical power, with a convex object-side surface and a concave image-side surface. The third lens L3 has negative optical power, with a convex object-side surface and a concave image-side surface. The fourth lens L4 has positive optical power, with both its object-side and image-side surfaces being convex. The fifth lens L5 has negative optical power, with both its object-side and image-side surfaces being concave. The filter IR has both an object-side surface and an image-side surface. The incident light rays pass sequentially through the first lens L1 and the first working surface 110 into the first prism P1, then exit through the second working surface 120 and pass sequentially through the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5 and the third working surface 210 into the second prism P2. After the first reflection by the fifth working surface 230, the light rays are reflected to the fourth working surface 220, then reflected a second time by the fourth working surface 220, and finally exit through the fifth working surface 230 and pass through the object side and image side of the filter IR, and finally form an image on the imaging surface IMG.

[0099] Table 5 shows the basic parameters of the telephoto lens in Example 3, where the units for radius of curvature, thickness, and focal length are all millimeters (mm).

[0100] Table 5:

[0101]

[0102] Table 6 shows the higher-order coefficients that can be used for each aspherical mirror in Example 3, wherein each aspherical surface shape can be defined by formula (1) given in Example 1 above.

[0103] Table 6:

[0104]

[0105] In Embodiment 3, the optical power distribution of the first lens L1 to the fifth lens L5, the optical power, spacing and refractive index of each lens, and the angle and thickness of the first prism P1 and the second prism P2 are reasonably allocated and set according to the table above. While satisfying the focal length, the height of the first lens assembly 10 and the second lens assembly 20 is compressed, which can achieve the effect of large target surface, large aperture and short optical length, effectively reducing the overall height and making the lens miniaturized. Among them, the field of view of the telephoto lens is 31°, the aperture value of the telephoto lens is 2.6, the focal length f of the telephoto lens is 18.6mm, the working wavelength of the telephoto lens is 420~680nm, and the imaging circle diameter of the telephoto lens is 9.6mm. The relationship between the focal length f1 of the first lens L1 and the focal length f of the telephoto lens is f1 / f = 1.12; the relationship between the focal length f2 of the second lens L2 and the focal length f of the telephoto lens is f2 / f = 0.64; the relationship between the focal length f5 of the fifth lens L5 and the focal length f of the telephoto lens is abs(f5) / f = 0.29; the relationship between the equivalent thickness H4 of the first prism P1, the focal length f of the telephoto lens, and the aperture F# of the telephoto lens is |H4-f| / F# = 13.45; the relationship between the equivalent thickness H15 of the second prism P2 and the focal length f of the telephoto lens is H15 / f = 0.56; the relationship between the thickness OAL1 between the object side of the second lens L2 and the image side of the fifth lens L5 and the equivalent thickness H15 of the second prism P2 is OAL1 / H15. =0.44; The relationship between the radius of curvature r1 of the object side surface of the first lens L1 and the radius of curvature r2 of the object side surface of the second lens L2 is r1 / r2=1.30; The relationship between the equivalent thickness H2 of the first lens L1 and the equivalent thickness H4 of the first prism P1 is H2 / H4=0.24; The relationship between the focal length f of the telephoto lens and the aperture F# of the telephoto lens is f / F#=7.15; The relationship between the distance OAL2 from the fifth working surface 230 to the imaging surface IMG and the aperture F# of the telephoto lens is OAL2 / F#=0.39; The relationship between the focal length f1 of the first lens L1, the focal length f2 of the second lens L2 and the focal length f5 of the fifth lens L5 is (f1+f2) / abs(f5)=6.1; The Abbe number Ab1 of the first lens L1 is 68.3.

[0106] Figure 11 The MTF curve of the telephoto lens in Example 3 is shown. The MTF (Modulation Transfer Function) curve shows the transmission of image details (i.e. image contrast) at different spatial frequencies by the imaging system. At a spatial frequency of 90 lp / mm, the MTF value is greater than 0.5, indicating good resolution and good imaging effect. Figure 12The optical fan diagram of the telephoto lens of Example 3 is shown. The optical fan diagram typically shows the cross-section of the light beam at different positions, as well as the path and changes in the propagation of the beam in the optical system. It is a comprehensive evaluation diagram of various aberrations, with a scale of ±20µm, that is, the scale range in the horizontal and vertical directions is ±20µm, and various aberrations are well corrected. Figure 13 The diagram shows the relative illumination and Y-field of view of the telephoto lens in Example 3. The relative illumination is greater than 0.6, and the illumination is uniform. According to... Figures 11 to 13 As can be seen, the telephoto lens given in Example 3 has well-corrected aberrations, uniform illumination, and good resolution, and can achieve good image quality.

[0107] Table 7 shows the relevant parameters of the telephoto lenses in Examples 1, 2 and 3, where the units for radius of curvature, equivalent thickness and focal length are millimeters (mm).

[0108] Table 7:

[0109]

[0110] In summary, Examples 1, 2, and 3 satisfy the relationships shown in Table 8.

[0111] Table 8:

[0112]

[0113] 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. A telephoto lens, characterized in that, The image sensor comprises, from the object side to the image side, a first lens assembly (10), a first prism (P1), a second lens assembly (20), a second prism (P2), and an image sensor. The first lens assembly (10) includes at least a first lens (L1). The first prism (P1) includes a first working surface (110) facing the first lens (L1) and a second working surface (120) facing the second lens assembly (20). The second prism (P2) includes a third working surface (210) facing the second lens assembly (20), a fifth working surface (230) facing the image sensor, and a fourth working surface (220) for a second reflection of incident light from the fifth working surface (230). The imaging plane (IMG) of the image sensor is positioned relative to the fifth working surface (230), which is used for a first reflection of incident light from the first working surface (110). The incident light from the fourth working surface (220) is emitted to the imaging surface (IMG). The thickness OAL1 of the second lens assembly (20) and the equivalent thickness H15 of the second prism (P2) satisfy: 0.25≤OAL1 / H15≤0.

85. The second lens assembly (20) includes a second lens (L2), a third lens (L3), a fourth lens (L4) and a fifth lens (L5) arranged in sequence. The first lens (L1), the second lens (L2) and the fourth lens (L4) have positive optical power, and the third lens (L3) and the fifth lens (L5) have negative optical power. The first lens assembly (10) has one lens with optical power, and the second lens assembly (20) has four lenses with optical power. The focal length f5 of the fifth lens (L5) and the focal length f of the telephoto lens satisfy: 0.15≤abs(f5) / f≤0.

75.

2. The telephoto lens according to claim 1, characterized in that, The focal length f1 of the first lens (L1) and the focal length f of the telephoto lens satisfy: 1≤f1 / f≤5.

3. The telephoto lens according to claim 1, characterized in that, The focal length f2 of the second lens (L2) and the focal length f of the telephoto lens satisfy: 0.2≤f2 / f≤0.

8.

4. The telephoto lens according to claim 1, characterized in that, The equivalent thickness H4 of the first prism (P1), the focal length f of the telephoto lens, and the aperture F# of the telephoto lens satisfy: 8≤|H4-f| / F#≤21.

5. The telephoto lens according to claim 1, characterized in that, The equivalent thickness H15 of the second prism (P2) and the focal length f of the telephoto lens satisfy: 0.25≤H15 / f≤1.

6. The telephoto lens according to claim 1, characterized in that, The radius of curvature r1 of the object side surface of the first lens (L1) and the radius of curvature r2 of the object side surface of the second lens (L2) satisfy: 1≤r1 / r2≤3.

7. The telephoto lens according to claim 1, characterized in that, The focal length f1 of the first lens (L1), the focal length f2 of the second lens (L2), and the focal length f5 of the fifth lens (L5) satisfy: 3≤(f1+f2) / abs(f5)≤11.

8. An electronic device, characterized in that, Including the telephoto lens as described in any one of claims 1 to 7.

Images