Telephoto lens and electronic equipment

Abstract

The invention discloses a telephoto lens. The telephoto lens sequentially comprises a first lens assembly, a first prism, a second lens assembly, a second prism and an image sensor from an object side to an image side, the first lens assembly at least comprises a first lens, and the first prism comprises a first working face facing the first lens and a second working face facing the second lens assembly. The second prism comprises a third working face facing the second lens assembly, a fifth working face facing the image sensor and a fourth working face used for reflecting incident light from the fifth working face for the second time, and an imaging face of the image sensor is arranged relative to the fifth working face. The thickness OAL1 of the second lens assembly and the equivalent thickness H15 of the second prism meet the condition that OAL1 / H15 is larger than or equal to 0.25 and smaller than or equal to 0.85. According to the telephoto lens, the overall height is effectively reduced, and miniaturization of the lens is facilitated. The invention further discloses the electronic equipment.

Description

Technical Field

[0001] The present invention relates to the technical field of optical imaging, and particularly to a telephoto lens and an electronic device. Background Art

[0002] With the increasing development of various electronic products towards multi-functionality, the camera function has become a standard configuration for electronic products such as smart phones and tablet computers.

[0003] However, with the continuous improvement of users' requirements for imaging quality, due to the relatively long back focal length of the telephoto lens, there are generally problems such as a relatively large lens height and protruding outside the body, which affect the overall appearance design and aesthetics of the whole machine. Summary of the Invention

[0004] In view of the above problems, the purpose of the present invention is to provide a telephoto lens, which can effectively reduce the overall height and is beneficial to the miniaturization of the lens.

[0005] The present invention provides a telephoto lens, which sequentially includes a first lens assembly, a first prism, a second lens assembly, a second prism, and an image sensor from the object side to the image side; the first lens assembly at least includes 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 the incident light from the fifth working surface for the second time, the imaging surface of the image sensor is arranged relative to the fifth working surface, the fifth working surface is used for reflecting the incident light from the first working surface for the first time and emitting the incident light from the fourth working surface to the imaging surface, and 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, the first lens, the second lens, and the fourth lens have positive optical powers, and the third lens and the fifth lens have negative optical powers.

[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 a diaphragm, and the diaphragm is disposed on the image side surface 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, and the filter is disposed between the fifth working surface and the imaging surface.

[0020] Optionally, the third working surface is perpendicular to the fourth working surface, 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, and the sixth working surface is used to reflect the incident light from the first working surface to the second working surface.

[0022] The present invention further provides an electronic device, including the above-mentioned telephoto lens.

[0023] By controlling the ratio between the thickness of the second lens assembly and the equivalent thickness of the second prism within a reasonable range, the telephoto lens provided by the present invention is beneficial to shortening the length of the second lens assembly, reducing the overall volume, facilitating the miniaturization of the lens, effectively reducing the overall height. At the same time, the light is reflected twice inside the second prism and then emitted to the imaging surface, and the back focal optical path of the lens is folded twice inside the second prism, which can further reduce the overall height and improve the imaging quality, thereby correspondingly improving the user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following will briefly introduce the drawings required for the embodiments. It should be understood that the following drawings only show some embodiments of the present invention, and therefore should not be regarded as limiting the scope. For those of ordinary skill in the art, without creative efforts, other related drawings can also be obtained based on these drawings.

[0025] Figure 1 FIG. shows a schematic structural diagram of a telephoto lens according to an embodiment of the present application.

[0026] Figure 2 FIG. shows a schematic structural diagram of the telephoto lens of Embodiment 1 of the present application.

[0027] Figures 3 to 5 FIGS. respectively show the MTF curve diagram, light fan diagram, relative illuminance and Y field angle diagram of the telephoto lens of Embodiment 1.

[0028] Figure 6 FIG. shows a schematic structural diagram of the telephoto lens of Embodiment 2 of the present application.

[0029] Figures 7 to 9 FIGS. respectively show the MTF curve diagram, light fan diagram, relative illuminance and Y field angle diagram of the telephoto lens of Embodiment 2.

[0030] Figure 10 FIG. shows a schematic structural diagram of the telephoto lens of Embodiment 3 of the present application.

[0031] Figures 11 to 13 FIGS. respectively show the MTF curve diagram, light fan diagram, relative illuminance and Y field angle diagram of the telephoto lens of Embodiment 3. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The foregoing 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 accompanying drawings. Through the description of the specific embodiments, a more in-depth and specific understanding of the technical means and effects adopted by the present invention to achieve the expected purpose can be obtained. However, the accompanying drawings are only for reference and illustration, and are not used to limit the present invention. Some well-known parts may not be shown. In each drawing, the same elements are denoted by similar reference numerals. For clarity, the various parts in the drawings are not necessarily drawn to scale exactly according to the actual objects.

[0033] It should be understood that the terms "first", "second", "third", "fourth", etc. are only used to distinguish elements or circuits with similar attributes, rather than indicating or implying relative importance or a specific order. The terms "comprising", "including" or any other variant thereof are intended to cover non-exclusive inclusion, and in addition to the listed elements, may also include other elements not specifically listed.

[0034] In the drawings, for the sake of convenience of illustration, the thickness, size and shape of the lens have been slightly exaggerated. Specifically, the spherical or aspherical shapes shown in the drawings are shown by way of example. That is, the spherical or aspherical shapes are not limited to the spherical or aspherical shapes shown in the drawings. The drawings are only for illustration 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 position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object to be photographed is called the object side surface of the lens, and the surface of each lens closest to the imaging surface IMG is called the image side surface of the lens.

[0036] It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0037] The features, principles and other aspects of the present application will be described in detail below.

[0038] Figure 1 The structural schematic diagram of a telephoto lens according to an embodiment of the present application is shown. As Figure 1As shown in the figure, a telephoto lens includes, in order 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 reflecting the incident light from the fifth working surface 230 for the second time. The imaging surface IMG of the image sensor is arranged relative to the fifth working surface 230. The fifth working surface 230 is used for reflecting the incident light from the first working surface 110 for the first time and for emitting the incident light from the fourth working surface 220 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.

[0039] When the telephoto lens of the present 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, passes through the second lens assembly 20 and the third working surface 210, and enters the second prism P2. It is reflected for the first time by the fifth working surface 230 and reflected to the fourth working surface 220, then reflected for the second time by the fourth working surface 220 and 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, facilitating the miniaturization of the lens, and effectively reducing the overall height. At the same time, by reflecting the light twice inside the second prism P2 and then emitting it to the imaging surface IMG, there is no need to occupy a large space to change the original direction of the light, and only a small optical path is required to reach the imaging surface IMG. The back focal length of the lens is correspondingly shortened, and the back focal optical path of the lens is folded twice inside the second prism P2, which can further reduce the overall height and improve the imaging quality, thereby improving 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 powers, and the third lens L3 and the fifth lens L5 have negative optical powers.

[0042] Specifically, the second working surface 120 faces the second lens L2, the third working surface 210 faces the fifth lens L5, the thickness OAL1 of the second lens assembly 20 is the thickness OAL1 between the object side surface of the second lens L2 and the image side surface of the fifth lens L5, and the thickness OAL1 between the object side surface of the second lens L2 and the image side surface 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 the present application is in use, incident light sequentially enters the first prism P1 through the first lens L1 and the first working surface 110, then exits through the second working surface 120 and sequentially passes through the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5 and the third working surface 210 and enters the second prism P2, is first reflected by the fifth working surface 230 and reflected to the fourth working surface 220, then is secondarily reflected by the fourth working surface 220 and reflected to the fifth working surface 230, and exits through the fifth working surface 230 to the imaging surface IMG.

[0044] Specifically, the first lens L1 has a positive optical power. The first lens L1 is the lens closest to the object side in the first lens assembly 10. The first lens L1 plays a main role in converging light rays in the entire optical system. The first prism P1 can correct the propagation path of the incident light as the position of the first lens L1 in the first lens assembly 10 changes through the first working surface 110 and the second working surface 120, so that the light rays can reach the second lens L2 after passing through a smaller optical path from the first prism P1, correspondingly shortening the back focal length of the lens. And through the combination of the positive and negative optical powers of multiple lenses, various aberrations can be balanced to obtain a clear image.

[0045] According to the optical power distribution of the first lens L1 to the fifth lens L5, and by reasonably allocating the optical powers, spacings and refractive indices of each lens, as well as the angles and thicknesses of the first prism P1 and the second prism P2, etc., and compressing the heights of the first lens assembly 10 and the second lens assembly 20 while satisfying the focal length, the effects of a large target surface, a large aperture and a short overall 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 imaging 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 light rays 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 ratio of the absolute value of the focal length f5 of the fifth lens L5 to 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, so that the actual aperture does not 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 is controlled, which is beneficial to the miniaturization of the lens.

[0051] In an exemplary embodiment, the curvature radius r1 of the object side surface of the first lens L1 and the curvature radius r2 of the object side surface of the second lens L2 satisfy: 1 ≤ r1 / r2 ≤ 3. By controlling the ratio of the curvature radius r1 of the object side surface of the first lens L1 to the curvature radius r2 of the object side surface of the second lens L2 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, ensuring the lens strength of the first lens L1.

[0053] In an exemplary embodiment, the focal length f of the telephoto lens and the aperture F# of the telephoto lens satisfy: 4 ≤ f / F# ≤ 10. By controlling the ratio of the focal length f of the telephoto lens to the aperture F# of the telephoto lens within a reasonable range, the light passing aperture is controlled, which is beneficial to 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 to the aperture F# of the telephoto lens 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 sum of the focal length f1 of the first lens L1 and the focal length f2 of the second lens L2 to the absolute value of the focal length f5 of the fifth lens L5 within a reasonable range, the focal lengths of the respective lenses can be controlled within a reasonable range, which is beneficial to 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 optimizing chromatic aberration.

[0057] In an exemplary embodiment, the telephoto lens further includes a diaphragm STO, and the diaphragm STO is disposed on the image side of the first prism P1, which is beneficial to reducing the effective aperture of the second lens assembly 20 and thus reducing the overall height.

[0058] In an exemplary embodiment, the telephoto lens further 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 to correcting the aberration generated by the imaging system.

[0059] In an exemplary embodiment, the third working surface 210 is perpendicular to the fourth working surface 220, and 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 inclined 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-reflected light, and the camera height can be significantly reduced. At the same time, since the imaging surface IMG is disposed opposite to the fifth working surface 230, the imaging surface IMG is inclined, and the image sensor is also inclined, further reducing the overall height.

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

[0061] The incident light passes through the first lens L1 and the first working surface 110 in sequence and enters the first prism P1, then is reflected by the sixth working surface 130 to the second working surface 120, and then exits through the second working surface 120.

[0062] Specifically, the first prism P1 is an isosceles right 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, and the second working surface 120 is connected to the sixth working surface 130. The sixth working surface 130 reflects the incident light entering the first prism P1 to deflect the light, so as to correct the propagation path of the incident light and further reduce the height of the camera.

[0063] In an exemplary embodiment, the first prism P1 is a flat glass. The first working surface 110 and the second working surface 120 are arranged in parallel. The incident light passes through the first lens L1 and the first working surface 110 in sequence and enters the first prism P1, and then exits through the second working surface 120, which is beneficial to correcting the propagation path of the incident light, so that the incident light can reach the second lens L2 after passing through a smaller optical path after exiting the first prism P1, correspondingly shortening the back focal length of the lens and reducing the overall height.

[0064] In an exemplary embodiment, a reflective film may be coated on the fourth working surface 220. Thus, when the incident light is reflected by the fourth working surface 220, it can be ensured that the incident light is completely reflected, reducing the risk that the incident light is refracted out of the second prism P2 when reflected by the fourth working surface 220. It can be understood that a part 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 that the light can be completely reflected, reducing the risk that the incident light is refracted out of the first prism P1 when reflected by the sixth working surface 130.

[0065] Based on the same inventive concept, the present application also provides an electronic device including the above-mentioned telephoto lens. The electronic device includes but is not limited to smartphones, tablet computers, laptop computers, gimbal shooting devices, surveillance cameras, and other imaging devices. The implementation of this electronic device can refer to the embodiments of the telephoto lens, and the repeated parts will not be described again.

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

[0067] Specific embodiments of the telephoto lens applicable to the above embodiments will be further described below with reference to the accompanying drawings.

[0068] Example 1 The following refers to Figure 2 Describe the telephoto lens according to Embodiment 1 of the present application.

[0069] The telephoto lens of Embodiment 1 sequentially includes a first lens assembly 10, a first prism P1, a second lens assembly 20, a second prism P2, and an image sensor from the object side to the image side; 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, a fifth working surface 230 facing the image sensor, and a fourth working surface 220 for reflecting the incident light from the fifth working surface 230 a second time. The imaging surface IMG of the image sensor is arranged relative to the fifth working surface 230. The fifth working surface 230 is used for reflecting the incident light from the first working surface 110 for the first time and for emitting the incident light from the fourth working surface 220 to the imaging surface IMG. The thickness OAL1 between the object side surface of the second lens L2 and the image side surface 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 powers, and the third lens L3 and the fifth lens L5 have negative optical powers. The aperture STO is arranged on the image side surface of the first prism P1. The filter IR is arranged 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.

[0070] The first lens L1 has a positive focal power, with its object side being convex and its image side being concave. The second lens L2 has a positive focal power, with its object side being convex and its image side being concave. The third lens L3 has a negative focal power, with its object side being concave and its image side being concave. The fourth lens L4 has a positive focal power, with its object side being convex and its image side being convex. The fifth lens L5 has a negative focal power, with its object side being concave and its image side being convex. The filter IR has an object side and an image side. Incident light passes through the first lens L1 and the first working surface 110 in sequence and enters the first prism P1, then exits through the second working surface 120 and passes through the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5 and the third working surface 210 in sequence and enters the second prism P2, is reflected for the first time by the fifth working surface 230 and reflected to the fourth working surface 220, then is reflected for the second time by the fourth working surface 220 and reflected to the fifth working surface 230, exits through the fifth working surface 230 and passes through the object side and the image side of the filter IR, and finally forms an image on the imaging surface IMG.

[0071] Table 1 shows the basic parameter table of the telephoto lens in Embodiment 1. Among them, the units of the radius of curvature, thickness, and focal length are all millimeters (mm).

[0072] Table 1:

[0073] Among them, L1-R1 represents the object side of the first lens L1, L1-R2 represents the image side of the first lens L1, P1-R1 represents the object side of the first prism P1, that is, the first working surface 110, P1-R2 represents the image side of the first prism P1, that is, the second working surface 120, L2-R1 represents the object side of the second lens L2, L2-R2 represents the image side of the second lens L2, L3-R1 represents the object side of the third lens L3, L3-R2 represents the image side of the third lens L3, 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, that is, the third working surface 210, P2-R2 represents the image side of the second prism P2, that is, 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.

[0074] In Embodiment 1, the object side and the image side of any one of the second lens L2 to the fifth lens L5 are both even aspherical surfaces. The surface profiles of each aspherical lens can be defined by, but not limited to, the following aspherical formula: (1) Among them, Z represents the height in the optical axis direction, c is the reciprocal of the surface radius, k is the conic coefficient, and r is the aperture in the radial direction; α represents the aspheric coefficient, α1 represents the aspheric coefficient A2, α2 represents the aspheric coefficient A4... Table 2 gives the high-order term coefficients A2, A4, A6, A8, A10, A12, A14, and A16 of each aspheric mirror surface used in Example 1.

[0075] Table 2:

[0076] In Example 1, based on the reasonable distribution and setting of the optical power distribution, the optical power, spacing, and refractive index of each of the first lens L1 to the fifth lens L5, as well as the angles and thicknesses of the first prism P1 and the second prism P2 in the above table, and while satisfying the focal length, compressing the height of the first lens assembly 10 and the second lens assembly 20, the effects of a large target surface, a large aperture, and a short overall optical length can be achieved, effectively reducing the overall height and miniaturizing the lens. Among them, the field of view angle of the telephoto lens is 33°, the aperture value of the telephoto lens is 2.45, the focal length f of the telephoto lens is 15.27 mm, the working wavelength band of the telephoto lens is 420 - 680 nm, and the imaging circle diameter of the telephoto lens is 9.6 mm. 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 from the object side of the second lens L2 to 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 curvature radius r1 of the object side of the first lens L1 and the curvature radius r2 of the object side 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 = 64.2.

[0077] Figure 3 The MTF curve graph of the telephoto lens of Embodiment 1 is shown. The MTF (Modulation Transfer Function) curve shows the transmission of the imaging system for image details (i.e., image contrast) at different spatial frequencies. Its MTF value is greater than 0.5 at a spatial frequency of 90 lp / mm, with good resolving power and good imaging effect. Figure 4 The fan diagram of the telephoto lens of Embodiment 1 is shown. The fan diagram usually shows the cross-section of the light beam at different positions, as well as the propagation path and changes in the optical system. It is a comprehensive evaluation diagram of various aberrations, with a scale of ±20um, that is, the scale range in the horizontal and vertical directions is ±20um, and various aberrations are corrected well. Figure 5 The relative illuminance and Y field angle graph of the telephoto lens of Embodiment 1 is shown. The relative illuminance is greater than 0.6, and the illuminance is uniform. According to Figures 3 to 5 It can be seen that the telephoto lens given in Embodiment 1 has well-corrected aberrations, uniform illuminance, and good resolving power, and can achieve good imaging quality.

[0078] Example 2 The following will refer to Figure 6 Describe the telephoto lens according to Embodiment 2 of the present application. In this embodiment, for the sake of simplicity, some descriptions similar to those in Embodiment 1 will be omitted.

[0079] The telephoto lens of Embodiment 2 sequentially includes a first lens assembly 10, a first prism P1, a second lens assembly 20, a second prism P2, and an image sensor from the object side to the image side; the first lens assembly 10 includes a first lens L1, 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, a fifth working surface 230 facing the image sensor, and a fourth working surface 220 for reflecting the incident light from the fifth working surface 230 for the second time, the imaging surface IMG of the image sensor is arranged relative to the fifth working surface 230, the fifth working surface 230 is used for reflecting the incident light from the first working surface 110 for the first time and for emitting the incident light from the fourth working surface 220 to the imaging surface IMG, the thickness OAL1 between the object side surface of the second lens L2 and the image side surface 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 powers, and the third lens L3 and the fifth lens L5 have negative optical powers. The aperture STO is arranged on the image side surface of the first prism P1. The filter IR is arranged 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, 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°, 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.

[0080] The first lens L1 has a positive focal power, with its object side being convex and its image side being concave. The second lens L2 has a positive focal power, with its object side being convex and its image side being concave. The third lens L3 has a negative focal power, with its object side being concave and its image side being concave. The fourth lens L4 has a positive focal power, with its object side being convex and its image side being convex. The fifth lens L5 has a negative focal power, with its object side being concave and its image side being convex. The filter IR has an object side and an image side. The incident light passes through the first lens L1 and the first working surface 110 in sequence and enters the first prism P1, then exits through the second working surface 120 and passes through the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5 and the third working surface 210 in sequence and enters the second prism P2, is reflected for the first time by the fifth working surface 230 and reflected to the fourth working surface 220, then is reflected for the second time by the fourth working surface 220 and reflected to the fifth working surface 230, exits through the fifth working surface 230 and passes through the object side and the image side of the filter IR, and finally forms an image on the imaging surface IMG.

[0081] Table 3 shows the basic parameter table of the telephoto lens of Example 2, where the units of the radius of curvature, thickness, and focal length are all millimeters (mm).

[0082] Table 3:

[0083] Table 4 shows the high-order term coefficients of the aspherical mirror surfaces that can be used in Example 2, where each aspherical surface type can be defined by the formula (1) given in the above Example 1.

[0084] Table 4:

[0085] In Embodiment 2, based on the reasonable allocation and setting of the optical power distribution of the first lens L1 to the fifth lens L5, the optical power, spacing, and refractive index of each lens, as well as the angles and thicknesses of the first prism P1 and the second prism P2 in the above table, while satisfying the focal length, the height of the first lens assembly 10 and the second lens assembly 20 can be compressed, achieving the effects of a large target surface, a large aperture, and a short overall optical length, effectively reducing the overall height and miniaturizing the lens. Among them, the field of view angle of the telephoto lens is 32°, the aperture value of the telephoto lens is 2.5, the focal length f of the telephoto lens is 16.453 mm, the working wavelength band of the telephoto lens is 420 - 680 nm, and the imaging circle diameter of the telephoto lens is 9.6 mm. 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 from the object side of the second lens L2 to 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 curvature radius r1 of the object side of the first lens L1 and the curvature radius r2 of the object side 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.

[0086] Figure 7 The MTF curve graph of the telephoto lens in Embodiment 2 is shown. The MTF (Modulation Transfer Function) curve shows the transmission of the imaging system for image details (i.e., image contrast) at different spatial frequencies. Its MTF value is greater than 0.5 at a spatial frequency of 90 lp / mm, indicating good resolution and good imaging effect. Figure 8The fan diagram of the telephoto lens of Embodiment 2 is shown. The fan diagram generally shows the cross-section of the light beam at different positions, as well as the propagation path and changes in the optical system. It is a comprehensive evaluation diagram of various aberrations, with a scale of ±20um, that is, the scale range in the horizontal and vertical directions is ±20um, and various aberrations are corrected well. Figure 9 The relative illuminance and Y field angle diagram of the telephoto lens of Embodiment 2 are shown. The relative illuminance is greater than 0.6, and the illuminance is uniform. According to Figures 7 to 9 It can be seen that the telephoto lens given in Embodiment 2 has well-corrected aberrations, uniform illuminance, and good resolving power, and can achieve good imaging quality.

[0087] Example 3 The following refers to Figure 10 Describe the telephoto lens according to Embodiment 3 of the present application. In this embodiment, for the sake of simplicity, some descriptions similar to those in Embodiment 1 will be omitted.

[0088] The telephoto lens of Embodiment 3 sequentially includes a first lens assembly 10, a first prism P1, a second lens assembly 20, a second prism P2, and an image sensor from the object side to the image side; 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, a fifth working surface 230 facing the image sensor, and a fourth working surface 220 for reflecting the incident light from the fifth working surface 230 for the second time. The imaging surface IMG of the image sensor is arranged relative to the fifth working surface 230. The fifth working surface 230 is used for reflecting the incident light from the first working surface 110 for the first time and emitting the incident light from the fourth working surface 220 to the imaging surface IMG. The thickness OAL1 between the object side surface of the second lens L2 and the image side surface 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 powers, and the third lens L3 and the fifth lens L5 have negative optical powers. The aperture stop STO is arranged on the image side surface of the first prism P1. The filter IR is arranged 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, 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°, 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.

[0089] The first lens L1 has a positive optical power, with its object side being convex and its image side being concave. The second lens L2 has a positive optical power, with its object side being convex and its image side being concave. The third lens L3 has a negative optical power, with its object side being convex and its image side being concave. The fourth lens L4 has a positive optical power, with its object side being convex and its image side being convex. The fifth lens L5 has a negative optical power, with its object side being concave and its image side being concave. The filter IR has an object side and an image side. The incident light passes through the first lens L1 and the first working surface 110 in sequence and enters the first prism P1, then exits through the second working surface 120 and passes through the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5 and the third working surface 210 in sequence and enters the second prism P2, is reflected for the first time by the fifth working surface 230 and reflected to the fourth working surface 220, then is reflected for the second time by the fourth working surface 220 and reflected to the fifth working surface 230, exits through the fifth working surface 230 and passes through the object side and the image side of the filter IR, and finally forms an image on the imaging surface IMG.

[0090] Table 5 shows the basic parameter table of the telephoto lens of Example 3, where the units of the radius of curvature, thickness, and focal length are all millimeters (mm).

[0091] Table 5:

[0092] Table 6 shows the higher-order term coefficients of the aspherical mirrors that can be used in Example 3, where each aspherical surface type can be defined by the formula (1) given in the above Example 1.

[0093] Table 6:

[0094] In Embodiment 3, based on the reasonable allocation and setting of the optical power distribution of the first lens L1 to the fifth lens L5, the optical power, spacing, and refractive index of each lens, as well as the angles and thicknesses of the first prism P1 and the second prism P2 in the above table, and while satisfying the focal length, the heights of the first lens assembly 10 and the second lens assembly 20 are compressed, achieving the effects of a large target surface, a large aperture, and a short overall optical length, effectively reducing the overall height and miniaturizing the lens. Among them, the field of view angle 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 18.6 mm, the working wavelength range of the telephoto lens is 420 - 680 nm, and the imaging circle diameter of the telephoto lens is 9.6 mm. 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 from the object side of the second lens L2 to 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 curvature radius r1 of the object side of the first lens L1 and the curvature radius r2 of the object side 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.

[0095] Figure 11 The MTF curve graph of the telephoto lens in Embodiment 3 is shown. The MTF (Modulation Transfer Function) curve shows the transmission of the imaging system for image details (i.e., image contrast) at different spatial frequencies. Its MTF value is greater than 0.5 at a spatial frequency of 90 lp / mm, indicating good resolution and good imaging effect. Figure 12The fan diagram of the telephoto lens of Embodiment 3 is shown. The fan diagram generally shows the cross-section of the light beam at different positions, as well as the propagation path and changes in the optical system. It is a comprehensive evaluation diagram of various aberrations, with a scale of ±20um, that is, the scale range in the horizontal and vertical directions is ±20um, and various aberrations are corrected well. Figure 13 The relative illuminance and Y field angle diagram of the telephoto lens of Embodiment 3 are shown. The relative illuminance is greater than 0.6, and the illuminance is uniform. According to Figures 11 to 13 It can be seen that the telephoto lens given in Embodiment 3 has well-corrected aberrations, uniform illuminance, and good resolution, and can achieve good imaging quality.

[0096] Table 7 shows the relevant parameter table of the telephoto lenses of Embodiment 1, Embodiment 2, and Embodiment 3. Among them, the units of the radius of curvature, equivalent thickness, and focal length are all millimeters (mm).

[0097] Table 7:

[0098] In summary, Embodiment 1, Embodiment 2, and Embodiment 3 respectively satisfy the relationships shown in Table 8.

[0099] Table 8:

[0100] The above description is only the preferred embodiments of the present application and the description of the applied technical principles. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solutions formed by the specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the inventive concept. For example, the technical solutions formed by mutually replacing the above features with the technical features (but not limited to) having similar functions disclosed in the present application.

Claims

1. A telephoto lens, characterized in that: The invention 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) comprises at least a first lens (L1); the first prism (P1) comprises 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) comprises a third working surface (210) facing the second lens assembly (20), a fifth working surface (230) facing the image sensor and a second working surface (240) for future use; A fourth working surface (220) is provided on which incident light from the fifth working surface (230) is reflected for a second time, an imaging surface (IMG) of the image sensor is arranged relative to the fifth working surface (230), the fifth working surface (230) is used to reflect incident light from the first working surface (110) for a first time and to emit incident light from the fourth working surface (220) to the imaging surface (IMG), and a thickness OAL1 of the second lens assembly (20) and an equivalent thickness H15 of the second prism (P2) satisfy the following conditions: 0.25≤OAL1 / H15≤0.

85.

2. The telephoto lens according to claim 1, characterized in that: The second lens assembly (20) comprises 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) having positive optical power, and the third lens (L3) and the fifth lens (L5) having negative optical power.

3. The telephoto lens according to claim 2, 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.

4. The telephoto lens according to claim 2, 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.

5. The telephoto lens according to claim 2, wherein: 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.

6. The telephoto lens according to claim 2, wherein: 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.

7. The telephoto lens according to claim 2, wherein: The equivalent thickness H15 of the second prism (P2) and the focal length f of the telephoto lens satisfy: 0.25≤H15 / f≤1.

8. The telephoto lens according to claim 2, wherein: A curvature radius r1 of the object side surface of the first lens (L1) and a curvature radius r2 of the object side surface of the second lens (L2) satisfy: 1≤r1 / r2≤3.

9. The telephoto lens according to claim 2, wherein: A focal length f1 of the first lens (L1), a focal length f2 of the second lens (L2), and a focal length f5 of the fifth lens (L5) satisfy: 3≤(f1+f2) / abs(f5)≤11.

10. An electronic device, characterized in that: Comprising the telephoto lens as claimed in any one of claims 1 to 9.

Images