Telephoto lens and electronic equipment

Abstract

The utility model discloses a telephoto lens and electronic equipment. The telephoto lens sequentially comprises a lens assembly, a prism and an image surface from an object space to an image space, the lens assembly sequentially comprises a first lens, a second lens, a third lens and a fourth lens. The first lens has positive focal power; the second lens has negative focal power; the third lens has positive focal power; the fourth lens has negative focal power; the prism is provided with an incident surface, a first reflecting surface, a first total reflection surface, a second total reflection surface, a second reflecting surface and an emergent surface, the incident surface and the emergent surface are arranged oppositely, and the focal length f'of the system and the focal power phi 1 of the first lens meet the condition that f ' / phi 1 is larger than or equal to 400 and smaller than or equal to 500; after passing through the lens assembly, light enters the prism from the incident surface, is reflected by the first reflecting surface, the first fully reflecting surface, the second fully reflecting surface and the second reflecting surface in sequence, and is emitted from the emergent surface to the image surface for imaging. The utility model has the advantages of long focus and miniaturization, and can be used for equipment such as light and thin smart phones.

Description

Technical Field

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

[0002] With the rapid development of mobile communication technology and the widespread use of smartphones, the functions and application scenarios of mobile phone lenses are constantly being enriched and expanded. Among them, in order to photograph distant objects, a longer focal length is required. As a result, telephoto lenses, as a functional module that enables long-distance shooting and optical zoom, have received widespread attention in the smartphone market.

[0003] However, a longer focal length means a longer optical path, resulting in a larger lens size, making it difficult to use in thin and light devices such as smartphones. Utility Model Content

[0004] In view of the above problems, the purpose of this utility model is to provide a telephoto lens and electronic device, which has the advantages of telephoto and miniaturization, and can be used in thin and light smartphones and other devices.

[0005] This utility model provides a telephoto lens, which includes a lens assembly, a prism, and an image plane in sequence from the object side to the image side; the lens assembly includes a first lens, a second lens, a third lens, and a fourth lens in sequence; the first lens has positive optical power; the second lens has negative optical power; the third lens has positive optical power; and the fourth lens has negative optical power; the prism has an incident surface, a first reflecting surface, a first total internal reflection surface, a second total internal reflection surface, a second reflecting surface, and an exit surface, with the incident surface and the exit surface arranged opposite to each other; the system focal length f′ of the telephoto lens and the first... The optical power Φ1 of a lens satisfies: 400≤f′ / φ1≤500; after passing through the lens assembly, the light rays are incident on the prism along the first optical axis through the incident surface, reflected by the first reflecting surface, incident on the first total internal reflection surface along the second optical axis, total internal reflection surface along the first total internal reflection surface, total internal reflection surface along the third optical axis, total internal reflection surface along the second total internal reflection surface, incident on the second reflecting surface along the fourth optical axis, and finally reflected by the second reflecting surface and exiting from the exit surface along the fifth optical axis to the image plane for imaging.

[0006] Optionally, the angle between the first optical axis and the second optical axis is between 0° and 90°, the angle between the second optical axis and the third optical axis is between 90° and 180°, the angle between the third optical axis and the fourth optical axis is between 90° and 180°, the angle between the fourth optical axis and the fifth optical axis is between 0° and 90°, and the first optical axis and the fifth optical axis are parallel to each other.

[0007] Optionally, the incident surface and the first total reflection surface are a common plane, and / or the second total reflection surface and the exit surface are a common plane.

[0008] Optionally, the optical power Φ1 of the first lens and the optical power Φ3 of the third lens satisfy: 1≤φ1 / φ3≤2.5.

[0009] Optionally, the Abbe number AB1 of the first lens and the Abbe number AB2 of the second lens satisfy: 25 ≤ AB1 - AB2.

[0010] Optionally, the dispersion coefficient N2 of the second lens and the dispersion coefficient N5 of the prism satisfy: 30 <N5-N2。

[0011] Optionally, the equivalent thickness H of the prism 11 The system focal length f′ of the telephoto lens satisfies: 0.5 <H 11 / f′<0.75.

[0012] Optionally, the object aspect height SAG9 and the image aspect height SAG10 of the fourth lens satisfy: |SAG9|≤0.4mm, |SAG10|≤0.4mm.

[0013] Optionally, the optical power Φ3 of the third lens satisfies: 0.03 < Φ3 < 0.07.

[0014] Optionally, the distance H between the fourth lens and the prism 10 The system focal length f′ of the telephoto lens satisfies: 0.01 <H 10 / f′<0.025.

[0015] Optionally, the angle A between the incident surface of the prism and the first reflecting surface after the optical path is folded satisfies: 29° < A < 35°.

[0016] Optionally, the distance H from the object-side vertex of the first lens to the prism 2-10 and the equivalent thickness H of the prism 11 Satisfy: 0.35≤(H) 2-10 ) / H 11 ≤0.45.

[0017] This invention also provides an electronic device, including the aforementioned telephoto lens.

[0018] The telephoto lens and electronic device provided by this utility model include, from object side to image side, a lens assembly, a prism, and an image plane. The lens assembly includes a first lens, a second lens, a third lens, and a fourth lens. The first lens has positive optical power; the second lens has negative optical power; the third lens has positive optical power; and the fourth lens has negative optical power. The prism has an incident surface, a first reflecting surface, a first total internal reflection surface, a second total internal reflection surface, a second reflecting surface, and an exit surface, with the incident surface and the exit surface arranged opposite to each other. The system focal length f′ of the telephoto lens and the optical power Φ1 of the first lens satisfy: 400≤f′ / φ1≤500, which is beneficial for converging light, achieving a relative aperture, improving image quality, and avoiding large aberrations caused by an excessively large relative aperture, as well as reduced brightness and resolution caused by an excessively small relative aperture. After passing through the lens assembly, light rays enter the prism along the first optical axis through the incident surface. After being reflected by the first reflecting surface, they enter the first total internal reflection surface along the second optical axis. After total internal reflection by the first total internal reflection surface, they enter the second total internal reflection surface along the third optical axis. After total internal reflection by the second total internal reflection surface, they enter the second reflecting surface along the fourth optical axis. After being reflected by the second reflecting surface, they exit from the exit surface along the fifth optical axis to form an image on the image plane. This invention utilizes an L-shaped periscope structure formed by four lenses and one prism to fully leverage space for imaging. The fewer lenses used reduce the overall height, and the back focal length is shortened by multiple folds inside the prism, further reducing the lens height. Through the rational allocation of the optical power, spacing, and refractive index of each lens, as well as the configuration of the prism, the telephoto lens possesses the advantages of both long focal length and miniaturization, making it suitable for thin and light devices such as smartphones. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model 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.

[0020] Figure 1 A schematic diagram of the structure of a telephoto lens according to an embodiment of this application is shown.

[0021] Figure 2 A schematic diagram of the structure of a telephoto lens according to Embodiment 1 of this application is shown.

[0022] Figures 3 to 6 The aperture fan diagram, distortion diagram, relative illumination and Y field of view diagram and MTF curve of the telephoto lens of Example 1 are shown respectively.

[0023] Figure 7A schematic diagram of the structure of a telephoto lens according to Embodiment 2 of this application is shown.

[0024] Figures 8 to 11 The light field diagram, distortion diagram, relative illumination and Y field of view diagram and MTF curve of the telephoto lens of Example 2 are shown respectively.

[0025] Figure 12 A schematic diagram of the structure of a telephoto lens according to Embodiment 3 of this application is shown.

[0026] Figures 13 to 16 The aperture fan diagram, distortion diagram, relative illumination and Y field of view diagram and MTF curve of the telephoto lens of Example 3 are shown respectively. Detailed Implementation

[0027] The foregoing and other technical contents, features, and effects of this utility model 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 can be gained of the technical means and effects adopted by this utility model to achieve its intended purpose. However, the accompanying drawings are for reference and illustration only and are not intended to limit this utility model; 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.

[0028] It is important to understand that the terms “first,” “second,” “third,” and “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.

[0029] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shape of the sphere shown in the drawings is illustrated by way of example. That is, the shape of the sphere is not limited to that shown in the drawings. The drawings are for illustrative purposes only and are not drawn strictly to scale.

[0030] 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 plane of the lens, and the surface of each lens closest to the image plane is called the image plane of the lens.

[0031] 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.

[0032] The features, principles and other aspects of this application are described in detail below.

[0033] like Figure 1 As shown, the telephoto lens according to an exemplary embodiment of this application includes, in order from object to image, a lens assembly, a prism L5, and an image plane IMG. The lens assembly includes, in order, a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4. The first lens L1 has positive optical power; the second lens L2 has negative optical power; the third lens L3 has positive optical power; and the fourth lens L4 has negative optical power. The prism L5 has an incident surface S51, a first reflecting surface S52, a first total internal reflection surface S53, a second total internal reflection surface S54, a second reflecting surface S55, and an exit surface S56, with the incident surface S51 and the exit surface S56 arranged opposite to each other. The system focal length f′ of the telephoto lens and the optical power Φ1 of the first lens L1 satisfy: 400≤f′ / φ1≤500, which is beneficial for converging light, achieving a relative aperture, improving image quality, avoiding large aberrations caused by an excessively large relative aperture, and avoiding reduced brightness and resolution caused by an excessively small relative aperture. After passing through the lens assembly, the light rays are incident on the prism L5 along the first optical axis through the incident surface S51. After being reflected by the first reflecting surface S52, the light rays are incident on the first total reflection surface S53 along the second optical axis. After being totally reflected by the first total reflection surface S53, the light rays are incident on the second total reflection surface S54 along the third optical axis. After being totally reflected by the second total reflection surface S54, the light rays are incident on the second reflecting surface S55 along the fourth optical axis. After being reflected by the second reflecting surface S55, the light rays are emitted from the exit surface S56 along the fifth optical axis to the image plane IMG for imaging. In this embodiment of the telephoto lens, among the four lenses in the lens assembly, the first lens L1 and the third lens L3 can focus light, and the third lens L3 can also correct aberrations. The second lens L2 and the fourth lens L4 can also correct aberrations. At the same time, the prism L5 can fold the light entering the prism L5 multiple times through the incident surface S51, the first reflecting surface S52, the first total reflection surface S53, the second total reflection surface S54, the second reflecting surface S55, and the exit surface S56. Thus, this utility model can make full use of space for imaging using an L-shaped periscope structure formed by four lenses and one prism L5. The use of fewer lenses can reduce the overall height, and the back focal length is shortened by multiple folds inside the prism L5, which also reduces the lens height. Through the reasonable allocation of the optical power, spacing, and refractive index of each lens and the configuration of the prism L5, the telephoto lens has the advantages of long focal length and miniaturization, and can be used in thin and light smartphones and other devices.

[0034] In an exemplary embodiment, the angle between the first and second optical axes is between 0° and 90°, the angle between the second and third optical axes is between 90° and 180°, the angle between the third and fourth optical axes is between 90° and 180°, and the angle between the fourth and fifth optical axes is between 0° and 90°. The first and fifth optical axes are parallel to each other. By controlling the angles between the first and fifth optical axes and ensuring that the first and fifth optical axes are parallel to each other, it is beneficial to control the folding direction of the light rays, ensuring that the light rays enter at the incident surface S51, and after multiple reflections, exit at the exit surface S56 opposite to the incident surface S51, and form an image on the image plane.

[0035] In an exemplary embodiment, the incident surface S51 and the first total reflection surface S53 are common planes, and / or, the second total reflection surface S54 and the exit surface S56 are common planes. In other exemplary embodiments, the incident surface S51 and the first total reflection surface S53 are parallel planes, and / or, the second total reflection surface S54 and the exit surface S56 are parallel planes.

[0036] In one exemplary embodiment, according to the telephoto lens of this application, the prism L5 is a parallelogram prism. One side of the parallelogram prism is provided with an incident surface S51 and a first total reflection surface S53, and the opposite side is provided with a second total reflection surface S54 and an exit surface S56. The other two sides of the parallelogram prism are respectively provided with a first reflection surface S52 and a second reflection surface S55. However, this application is not limited to this; the prism can also be composed of multiple prisms spliced ​​together, and the multiple prisms can be fixedly connected by optical adhesive.

[0037] In an exemplary embodiment, the lenses in the lens assembly of the telephoto lens according to this application can all be aspherical. For example, the first lens L1, the second lens L2, the third lens L3 and the fourth lens L4 are all aspherical. Aspherical lenses can better correct spherical aberration, reduce chromatic aberration and improve light transmittance, and can more accurately control the focusing and distribution of light, thereby improving image quality.

[0038] In one exemplary embodiment, according to the telephoto lens of this application, the first lens L1 is meniscus and convex towards the object side, the second lens L2 is meniscus and convex towards the object side, the third lens L3 is meniscus and convex towards the object side, and the fourth lens L4 is meniscus and convex towards the object side. In another exemplary embodiment, according to the telephoto lens of this application, the first lens L1 is meniscus and convex towards the object side, the second lens L2 is biconcave, the third lens L3 is biconvex, and the fourth lens L4 is biconcave.

[0039] In an exemplary embodiment, for the telephoto lens according to the present application, one or more of the first reflecting surface S52, the first total reflecting surface S53, the second total reflecting surface S54, and the second reflecting surface S55 are coated with a reflective film, which can be a metal film or a dielectric film, ensuring that light can be completely reflected and reducing the risk of light being refracted out of the prism L5.

[0040] In an exemplary embodiment, the telephoto lens according to the present application satisfies 1≤φ1 / φ3≤2.5; where, the optical power of the first lens L1 is Φ1, and the optical power of the third lens L3 is Φ3. Satisfying 1≤φ1 / φ3≤2.5, by controlling the ratio of the optical power Φ1 of the first lens L1 to the optical power Φ3 of the third lens L3, it is beneficial to correct spherical aberration and coma and improve the imaging quality.

[0041] In an exemplary embodiment, the telephoto lens according to the present application satisfies 25≤AB1 - AB2; where, the Abbe number of the first lens L1 is AB1, and the Abbe number of the second lens L2 is AB2. Satisfying 25≤AB1 - AB2, by controlling the difference between the Abbe number AB1 of the first lens L1 and the Abbe number AB2 of the second lens L2, it is beneficial to correct chromatic aberration and improve the imaging quality.

[0042] In an exemplary embodiment, the telephoto lens according to the present application satisfies 30 < N5 - N2; where, the dispersion coefficient of the second lens L2 is N2, and the dispersion coefficient of the prism L5 is N5. Satisfying 30 < N5 - N2, by controlling the difference between the dispersion coefficient N2 of the second lens L2 and the dispersion coefficient N5 of the prism L5, it is beneficial to chromatic aberration correction and improve the imaging quality.

[0043] In an exemplary embodiment, the telephoto lens according to the present application satisfies 0.5 < H 11 / f′ < 0.75; where, the equivalent thickness of the prism L5 is H 11 , and the system focal length of the telephoto lens is f′. Satisfying 0.5 < H 11 / f′ < 0.75, by controlling the ratio of the equivalent thickness H 11 of the prism L5 to the system focal length f′ of the telephoto lens, it is beneficial to control the multiple reflections of light in the prism L5 and satisfy the optical path of light in the prism L5 to achieve long focal length and miniaturization.

[0044] In an exemplary embodiment, the telephoto lens according to this application satisfies |SAG9|≤0.4mm and |SAG10|≤0.4mm; wherein, the object-oriented height of the fourth lens L4 is SAG9, and the image-oriented height of the fourth lens L4 is SAG10. Satisfying |SAG9|≤0.4mm and |SAG10|≤0.4mm, by controlling the object-oriented height SAG9 and the image-oriented height SAG10 of the fourth lens L4, it is beneficial to control the shape of the fourth lens L4, improve the manufacturability of the lens, reduce the angle between the light and the lens, optimize aberration values, and improve the lens imaging quality.

[0045] In an exemplary embodiment, the telephoto lens according to this application satisfies 0.03 < Φ3 < 0.07; wherein, the optical power of the third lens L3 is Φ3. Satisfying 0.03 < Φ3 < 0.07, by controlling the optical power Φ3 of the third lens L3, is beneficial for further light convergence, thus satisfying the aperture requirement.

[0046] In an exemplary implementation, reference may be made to Figure 1 The telephoto lens according to this application can meet the requirement of 0.01. <H 10 / f′<0.025; where the distance between the fourth lens L4 and the prism L5 is H. 10 The system focal length of the telephoto lens is f′. It satisfies 0.01. <H 10 / f′<0.025, by controlling the distance H between the fourth lens L4 and the prism L5 10 The ratio of the system focal length f′ of the telephoto lens to the focal length of the telephoto lens helps to meet the focusing distance of lenses with different focal lengths and avoids collision between the fourth lens L4 and the prism L5.

[0047] In an exemplary embodiment, the telephoto lens according to this application can satisfy 0.35 ≤ (H 2-10 ) / H 11 ≤0.45; where the distance from the vertex of the object side surface of the first lens L1 to the prism L5 is H. 2-10 The equivalent thickness H of prism L5 11 Satisfying 0.35≤(H) 2-10 ) / H 11 ≤0.45, by controlling the distance H from the vertex of the object side surface of the first lens L1 to the prism L5. 2-10 Equivalent thickness H of prism L5 11 By adjusting the ratio of the two elements, the overall thickness of the lens assembly can be reasonably reduced, the system volume can be controlled, and the lens can be miniaturized.

[0048] In an exemplary embodiment, the telephoto lens according to this application satisfies n1 < 1.6 and V1 > 50; wherein, the refractive index of the first lens L1 is n1, and the dispersion coefficient of the first lens L1 is V1. Satisfying n1 < 1.6 and V1 > 50, by controlling the refractive index n1 and the dispersion coefficient of the first lens L1, the first lens L1 has a low refractive index and a high dispersion coefficient, which is beneficial to reduce the dispersion entering the optical system, reduce the difficulty of correcting aberrations in other lenses, make the lens shape more reasonable, reduce the sensitivity of the system, and also reduce the processing and assembly difficulty of the lens.

[0049] In an exemplary embodiment, the telephoto lens according to this application satisfies 29° < A < 35°; wherein, the angle between the incident surface S51 and the first reflecting surface S52 of the prism L5 after folding the optical path is A. Satisfying 31° < A < 35°, by controlling the angle A between the incident surface S51 and the first reflecting surface S52 of the prism L5 after folding the optical path, the thickness of the prism L5 after folding the optical path can be controlled, which is beneficial for miniaturizing mobile phone lenses. In one embodiment, the telephoto lens according to this application satisfies 29° < B < 35°; wherein, the angle between the exit surface S56 and the second reflecting surface S55 of the prism L5 after folding the optical path is B.

[0050] In an exemplary embodiment, the intersection of the incident surface S51 and the first reflecting surface S52 of the prism L5 (angle A) and / or the intersection of the exiting surface S56 and the second reflecting surface S55 of the prism L5 (angle B) may be provided with chamfers or rounded corners. The tangent of the chamfer may be perpendicular to the first surface S10. By chamfering or rounding, the lateral length of the incident surface S51 and / or the exiting surface S56 of the prism L5 can be reduced, thereby reducing the overall lateral length of the prism L5. This saves internal space in the lens, helps improve module reliability, and reduces stray light. However, the present invention is not limited to this. Other intersections of the surfaces of the prism L1 may also be modified by chamfering or rounding as needed to save internal space in the camera module, improve the manufacturing yield of the prism L5, improve overall reliability, and provide a certain degree of anti-stray light effect.

[0051] In an exemplary embodiment, the telephoto lens according to this application further includes an aperture stop STO, which is disposed between the third lens L3 and the fourth lens L4 to further improve overall performance. In other exemplary embodiments, the aperture stop STO may be disposed between other lenses.

[0052] In an exemplary embodiment, the telephoto lens according to this application further includes a color filter IR for correcting color aberrations and / or a protective glass for protecting the photosensitive element located on the image plane IMG. In one exemplary embodiment, the color filter IR and / or the protective glass may be disposed between the image plane IMG and the exit surface S56 of the prism L5.

[0053] Based on the same inventive concept, the electronic device according to the exemplary embodiments of this application includes the telephoto lens described above. 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 refer to embodiments of the telephoto lens; repeated details will not be elaborated further.

[0054] However, those skilled in the art will understand that the number of lenses constituting the optical imaging lens can be varied to obtain the various results and advantages described herein without departing from the technical solutions claimed in this application. For example, although four lenses are described as an example in the embodiments, the optical imaging lens is not limited to including four lenses. If desired, the optical imaging lens may also include other numbers of lenses.

[0055] The following describes in further detail, with reference to the accompanying drawings, specific embodiments of the telephoto lens applicable to the above-described embodiments.

[0056] Example 1

[0057] The following is for reference Figure 2 A telephoto lens according to Embodiment 1 of this application is described. Figure 2 A schematic diagram of the telephoto lens according to Embodiment 1 of this application is shown. Figure 2 As shown, the telephoto lens, from object side to image side, includes a lens assembly, a prism L5, and an image plane IMG in sequence. The lens assembly includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4. The first lens L1 has positive optical power; the second lens L2 has negative optical power; the third lens L3 has positive optical power; and the fourth lens L4 has negative optical power. The prism L5 has an incident surface S51, a first reflecting surface S52, a first total internal reflection surface S53, a second total internal reflection surface S54, a second reflecting surface S55, and an exit surface S56, with the incident surface S51 and the exit surface S56 arranged opposite to each other. An aperture stop STO can be positioned between the third lens L3 and the fourth lens L4. An IR filter can be positioned between the image plane IMG and the exit surface S56 of the prism L5.

[0058] Please refer to the following as well. Figure 2As per Table 1, the first lens L1 has positive optical power, with its object surface L1R1 being convex and its image surface L1R2 being concave. The second lens L2 has negative optical power, with its object surface L2R1 being convex and its image surface L2R2 being concave. The third lens L3 has positive optical power, with its object surface L3R1 being convex and its image surface L3R2 being concave. The fourth lens L4 has negative optical power, with its object surface L4R1 being convex and its image surface L4R2 being concave. The incident surface S51 of the prism L5 is positioned opposite to the fourth lens L4, and the exit surface S56 of the prism L5 can be positioned opposite to the object surface of the filter IR. The filter IR has an object surface IRR1 and an image surface IRR2. After passing through the first lens L1, the second lens L2, the third lens L3, the aperture stop STO, and the fourth lens L4 in the lens assembly, the light enters the prism L5 from the incident surface S51. It is then reflected sequentially by the first reflecting surface S52, the first total reflection surface S53, the second total reflection surface S54, and the second reflecting surface S55, and finally forms an image on the image plane IMG.

[0059] Table 1 shows the basic parameters of the telephoto lens of Example 1, where the units for radius of curvature, thickness, and sagitta are millimeters (mm).

[0060] Table 1:

[0061]

[0062] In Embodiment 1, the object and image aspects of the first lens L1 to the fourth lens L4 can both be extended aspherical surfaces, and the surface shape of each extended aspherical surface can be defined using, but is not limited to, the following aspherical formula:

[0063] (1)

[0064] Where x is the distance vector from the vertex of the extended aspherical surface at a height h along the optical axis; c is the paraxial curvature of the extended aspherical surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the radius of curvature in Table 1 above); k is the conic coefficient; Ai is the i-th order correction coefficient of the extended aspherical surface. Table 2 shows the higher-order coefficients A4, A6, A8, A10, A12, A14 and A16 of the extended aspherical mirror surface that can be used for the object and image aspects of the first lens L1 to the fourth lens L4 in Embodiment 1.

[0065] Table 2:

[0066]

[0067] In this embodiment, based on the reasonable allocation of the optical power distribution, spacing, and refractive index of the first lens L1 to the fourth lens L4 in the above table, and the folding of the rear focal light rays under the equivalent thickness of the prism L5, the long focal length and miniaturization of the long focal length lens can be achieved. Among them, the focal length of the long focal length lens is 33 mm, the aperture of the long focal length lens is 4.5, and the imaging circle diameter of the long focal length lens is 7.456 mm. The relationship between the system focal length f′ of the long focal length lens and the optical power Φ1 of the first lens L1 is f′ / φ1 = 478.261, satisfying: 400 ≤ f′ / φ1 ≤ 500. The relationship between the optical power Φ1 of the first lens L1 and the optical power Φ3 of the third lens L3 is φ1 / φ3 = 2.029, satisfying: 1 ≤ φ1 / φ3 ≤ 2.5. The relationship between the Abbe number AB1 of the first lens L1 and the Abbe number AB2 of the second lens L2 is AB1 - AB2 = 32.200, satisfying: 25 ≤ AB1 - AB2. The relationship between the dispersion coefficient N2 of the second lens L2 and the dispersion coefficient N5 of the prism L5 is N5 - N2 = 37.4, satisfying: 30 < N5 - N2. The equivalent thickness H of the prism L5 11 and the relationship between the system focal length f′ of the long focal length lens is H 11 / f′ = 0.659, satisfying: 0.5 < H 11 / f′ < 0.75. The relationship between the sagittal height SAG9 on the object side of the fourth lens L4 and the sagittal height SAG10 on the image side of the fourth lens L4 is |SAG9| = 0.147 mm, |SAG10| = 0.285 mm, satisfying: |SAG9| ≤ 0.4 mm, |SAG10| ≤ 0.4 mm. The optical power Φ3 of the third lens L3 is Φ3 = 0.034, satisfying: 0.03 < Φ3 < 0.07. The distance H between the fourth lens L4 and the prism L5 10 and the relationship between the system focal length f′ of the long focal length lens is H 10 / f′ = 0.018, satisfying: 0.01 < H 10 / f′ < 0.025. The distance H from the vertex of the object side of the first lens L1 to the prism L5 2-10 and the equivalent thickness H of the prism L5 11 The relationship between them is (H 2-10 ) / H 11 = 0.425, satisfying: 0.35 ≤ (H 2-10 ) / H 11 ≤ 0.45. The angle A between the incident surface S51 and the first reflection surface S52 of the prism L5 after folding the optical path can be A = 30°, satisfying: 29° < A < 35°.

[0068] Figure 3 The fan diagram of the light of the long focal length lens in Embodiment 1 is shown, with a scale of ±10 μm, and the imaging magnification error values are all within an acceptable range. Figure 4The distortion diagram of the telephoto lens of Example 1 is shown, with distortion less than 1.0%, indicating good correction. Figure 5 The relative illumination and Y-field diagram of the telephoto lens of Example 1 are shown. The relative illumination is greater than 0.9, and the image illumination is uniform. Figure 6 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 250 lp / mm, the MTF modulus is greater than 0.1, indicating good resolution. According to... Figures 3 to 6 It can be seen that the telephoto lens given in Example 1 has small imaging error, good correction, uniform image illumination and good resolution, and can achieve good image quality.

[0069] Example 2

[0070] The following is for reference Figure 7 Describes a telephoto lens according to Embodiment 2 of this application. Figure 7 A schematic diagram of the telephoto lens according to Embodiment 2 of this application is shown. Figure 7 As shown, the telephoto lens, from object side to image side, includes a lens assembly, a prism L5, and an image plane IMG in sequence. The lens assembly includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4. The first lens L1 has positive optical power; the second lens L2 has negative optical power; the third lens L3 has positive optical power; and the fourth lens L4 has negative optical power. The prism L5 has an incident surface S51, a first reflecting surface S52, a first total internal reflection surface S53, a second total internal reflection surface S54, a second reflecting surface S55, and an exit surface S56, with the incident surface S51 and the exit surface S56 arranged opposite to each other. An aperture stop STO can be positioned between the third lens L3 and the fourth lens L4. An IR filter can be positioned between the image plane IMG and the exit surface S56 of the prism L5.

[0071] Please refer to the following as well. Figure 7As per Table 3, the first lens L1 has positive optical power, with its object surface L1R1 being convex and its image surface L1R2 being concave. The second lens L2 has negative optical power, with its object surface L2R1 being concave and its image surface L2R2 being concave. The third lens L3 has positive optical power, with its object surface L3R1 being convex and its image surface L3R2 being convex. The fourth lens L4 has negative optical power, with its object surface L4R1 being concave and its image surface L4R2 being concave. The incident surface S51 of the prism L5 is positioned opposite to the fourth lens L4, and the exit surface S56 of the prism L5 can be positioned opposite to the object surface of the filter IR. The filter IR has an object surface IRR1 and an image surface IRR2. After passing through the first lens L1, the second lens L2, the third lens L3, the aperture stop STO, and the fourth lens L4 in the lens assembly, the light enters the prism L5 from the incident surface S51. It is then reflected sequentially by the first reflecting surface S52, the first total reflection surface S53, the second total reflection surface S54, and the second reflecting surface S55, and finally forms an image on the image plane IMG.

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

[0073] Table 3:

[0074]

[0075] Table 4 shows the higher-order coefficients A4, A6, A8, A10, A12, A14, and A16 of the extended aspherical mirrors that can be used for the object and image aspects of the first lens L1 to the fourth lens L4 in Embodiment 2.

[0076] Table 4:

[0077]

[0078] In this embodiment, based on the reasonable allocation of the optical power distribution, spacing, and refractive index of the first lens L1 to the fourth lens L4 in the above table, and the folding of the rear focal rays under the equivalent thickness of the prism L5, the long focal length and miniaturization of the long focal length lens can be achieved. Among them, the focal length of the long focal length lens is 33 mm, the aperture of the long focal length lens is 4.5, and the imaging circle diameter of the long focal length lens is 7.466 mm. The relationship between the system focal length f′ of the long focal length lens and the optical power Φ1 of the first lens L1 is f′ / φ1 = 434.211, satisfying 400 ≤ f′ / φ1 ≤ 500. The relationship between the optical power Φ1 of the first lens L1 and the optical power Φ3 of the third lens L3 is φ1 / φ3 = 1.583, satisfying 1 ≤ φ1 / φ3 ≤ 2.5. The relationship between the Abbe number AB1 of the first lens L1 and the Abbe number AB2 of the second lens L2 is AB1 - AB2 = 32.200, satisfying 25 ≤ AB1 - AB2. The relationship between the dispersion coefficient N2 of the second lens L2 and the dispersion coefficient N5 of the prism L5 is N5 - N2 = 37.4, satisfying 30 < N5 - N2. The equivalent thickness H 11 of the prism L5 and the system focal length f′ of the long focal length lens have the relationship H 11 / f′ = 0.659, satisfying 0.5 < H 11 / f′ < 0.75. The relationship between the sag SAG9 on the object side of the fourth lens L4 and the sag SAG10 on the image side of the fourth lens L4 is |SAG9| = 0.247 mm, |SAG10| = 0.238 mm, satisfying |SAG9| ≤ 0.4 mm, |SAG10| ≤ 0.4 mm. The optical power Φ3 of the third lens L3 is Φ3 = 0.048, satisfying 0.03 < Φ3 < 0.07. The distance H 10 between the fourth lens L4 and the prism L5 and the system focal length f′ of the long focal length lens have the relationship H 10 / f′ = 0.018, satisfying 0.01 < H 10 / f′ < 0.025. The distance H 2-10 from the vertex of the object side of the first lens L1 to the prism L5 and the equivalent thickness H 11 of the prism L5 have the relationship (H 2-10 ) / H 11 = 0.437, satisfying 0.35 ≤ (H 2-10 ) / H 11 ≤ 0.45. The angle A between the incident surface S51 and the first reflection surface S52 of the prism L5 after folding the optical path can be A = 30°, satisfying 29° < A < 35°.

[0079] Figure 8 The fan diagram of the long focal length lens of Embodiment 2 is shown, with a scale of ±10 μm, and the imaging magnification error values are all within an acceptable range. Figure 9The distortion diagram of the telephoto lens of Example 2 is shown, with distortion less than 1.0%, indicating good correction. Figure 10 The relative illumination and Y-field diagram of the telephoto lens in Example 2 are shown. The relative illumination is greater than 0.9, and the image illumination is uniform. Figure 11 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 250 lp / mm, the MTF modulus is greater than 0.1, indicating good resolution. According to... Figures 8 to 11 It can be seen that the telephoto lens given in Example 2 has small imaging error, good correction, uniform image illumination and good resolution, and can achieve good image quality.

[0080] Example 3

[0081] The following is for reference Figure 12 Description of a telephoto lens according to Embodiment 3 of this application. Figure 12 A schematic diagram of the telephoto lens according to Embodiment 3 of this application is shown. Figure 12 As shown, the telephoto lens, from object side to image side, includes a lens assembly, a prism L5, and an image plane IMG in sequence. The lens assembly includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4. The first lens L1 has positive optical power; the second lens L2 has negative optical power; the third lens L3 has positive optical power; and the fourth lens L4 has negative optical power. The prism L5 has an incident surface S51, a first reflecting surface S52, a first total internal reflection surface S53, a second total internal reflection surface S54, a second reflecting surface S55, and an exit surface S56, with the incident surface S51 and the exit surface S56 arranged opposite to each other. An aperture stop STO can be positioned between the third lens L3 and the fourth lens L4. An IR filter can be positioned between the image plane IMG and the exit surface S56 of the prism L5.

[0082] Please refer to the following as well. Figure 12According to Table 5, the first lens L1 has positive optical power, with its object surface L1R1 being convex and its image surface L1R2 being concave. The second lens L2 has negative optical power, with its object surface L2R1 being concave and its image surface L2R2 being concave. The third lens L3 has positive optical power, with its object surface L3R1 being convex and its image surface L3R2 being convex. The fourth lens L4 has negative optical power, with its object surface L4R1 being concave and its image surface L4R2 being concave. The incident surface S51 of the prism L5 is positioned opposite to the fourth lens L4, and the exit surface S56 of the prism L5 can be positioned opposite to the object surface of the filter IR. The filter IR has an object surface IRR1 and an image surface IRR2. After passing through the first lens L1, the second lens L2, the third lens L3, the aperture stop STO, and the fourth lens L4 in the lens assembly, the light enters the prism L5 from the incident surface S51. It is then reflected sequentially by the first reflecting surface S52, the first total reflection surface S53, the second total reflection surface S54, and the second reflecting surface S55, and finally forms an image on the image plane IMG.

[0083] Table 5 shows the basic parameters of the telephoto lens in Example 3, where the units for radius of curvature, thickness, and sagitta are millimeters (mm).

[0084] Table 5:

[0085]

[0086] Table 6 shows the higher-order coefficients A4, A6, A8, A10, A12, A14, and A16 of the extended aspherical mirrors that can be used for the object and image aspects of the first lens L1 to the fourth lens L4 in Embodiment 3.

[0087] Table 6:

[0088]

[0089] In this embodiment, based on the reasonable allocation settings of the optical power distribution, spacing, and refractive index of the first lens L1 to the fourth lens L4 in the above table, as well as the folding of the rear focal rays under the equivalent thickness of the prism L5, the long focal length and miniaturization of the long focal length lens can be achieved. Among them, the focal length of the long focal length lens is 33 mm, the aperture of the long focal length lens is 4.5, and the imaging circle diameter of the long focal length lens is 7.456 mm. The relationship between the system focal length f′ of the long focal length lens and the optical power Φ1 of the first lens L1 is f′ / φ1 = 428.571, satisfying 400 ≤ f′ / φ1 ≤ 500. The relationship between the optical power Φ1 of the first lens L1 and the optical power Φ3 of the third lens L3 is φ1 / φ3 = 1.262, satisfying 1 ≤ φ1 / φ3 ≤ 2.5. The relationship between the Abbe number AB1 of the first lens L1 and the Abbe number AB2 of the second lens L2 is AB1 - AB2 = 32.200, satisfying 25 ≤ AB1 - AB2. The relationship between the dispersion coefficient N2 of the second lens L2 and the dispersion coefficient N5 of the prism L5 is N5 - N2 = 37.4, satisfying 30 < N5 - N2. The relationship between the equivalent thickness H 11 of the prism L5 and the system focal length f′ of the long focal length lens is H 11 / f′ = 0.659, satisfying 0.5 < H 11 / f′ < 0.75. The relationship between the sagittal height SAG9 on the object side of the fourth lens L4 and the sagittal height SAG10 on the image side of the fourth lens L4 is |SAG9| = 0.329 mm, |SAG10| = 0.214 mm, satisfying |SAG9| ≤ 0.4 mm and |SAG10| ≤ 0.4 mm. The optical power Φ3 of the third lens L3 is Φ3 = 0.061, satisfying 0.03 < Φ3 < 0.07. The distance H 10 between the fourth lens L4 and the prism L5 and the system focal length f′ of the long focal length lens is H 10 / f′ = 0.018, satisfying 0.01 < H 10 / f′ < 0.025. The distance H 2-10 from the vertex of the object side of the first lens L1 to the prism L5 and the equivalent thickness H 11 of the prism L5 have the relationship (H 2-10 ) / H 11 = 0.437, satisfying 0.35 ≤ (H 2-10 ) / H 11 ≤ 0.45. The angle A between the incident surface S51 and the first reflection surface S52 of the prism L5 after folding the optical path can be A = 30°, satisfying 29° < A < 35°.

[0090] Figure 13 shows the fan diagram of the long focal length lens of Embodiment 3, with a scale of ±10 μm, and the imaging magnification error values are all within an acceptable range. Figure 14The distortion diagram of the telephoto lens of Example 3 is shown, with distortion less than 1.0%, indicating good correction. Figure 15 The relative illumination and Y-field diagram of the telephoto lens in Example 3 are shown. The relative illumination is greater than 0.9, and the image illumination is uniform. Figure 16 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 250 lp / mm, the MTF modulus is greater than 0.1, indicating good resolution. According to... Figures 13 to 16 It can be seen that the telephoto lens given in Example 3 has small imaging error, good correction, uniform image illumination and good resolution, and can achieve good image quality.

[0091] In summary, Examples 1, 2, and 3 satisfy the relationships shown in Table 7.

[0092] Table 7:

[0093]

[0094] 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 utility model involved in this application is not limited to the 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 long focus lens characterized by, The long-focus lens comprises a lens assembly, a prism and an image plane in sequence from an object side to an image side; the lens assembly comprises a first lens, a second lens, a third lens and a fourth lens in sequence; the first lens has positive refractive power; the second lens has negative refractive power; the third lens has positive refractive power; the fourth lens has negative refractive power; the prism has an entrance surface, a first reflection surface, a first total reflection surface, a second total reflection surface, a second reflection surface and an exit surface, the entrance surface and the exit surface are oppositely arranged; the system focal length f' of the long-focus lens and the refractive power Φ1 of the first lens satisfy: 400 ≤ f' / φ1 ≤ 500. After passing through the lens assembly, the light ray is incident into the prism through the entrance surface along a first optical axis direction, is reflected by the first reflection surface, is incident into the first total reflection surface along a second optical axis direction, is totally reflected by the first total reflection surface, is incident into the second total reflection surface along a third optical axis direction, is totally reflected by the second total reflection surface, is incident into the second reflection surface along a fourth optical axis direction, is reflected by the second reflection surface, and is incident from the exit surface into the image plane along a fifth optical axis direction to form an image.

2. The telephoto lens of claim 1, wherein The refractive power Φ1 of the first lens and the refractive power Φ3 of the third lens satisfy: 1 ≤ φ1 / φ3 ≤ 2.

5.

3. The telephoto lens of claim 1, wherein, The Abbe number AB1 of the first lens and the Abbe number AB2 of the second lens satisfy: 25 ≤ AB1 - AB2.

4. The telephoto lens of claim 1, wherein, The dispersion coefficient N2 of the second lens and the dispersion coefficient N5 of the prism satisfy: 30 < N5 - N2.

5. The telephoto lens of claim 1, wherein, An equivalent thickness H of the prism 11 And a system focal length f' of the telephoto lens satisfies: 0.5 11 / H 6. The telephoto lens of claim 1, wherein, The sagittal height SAG9 of the fourth lens on the object side and the sagittal height SAG10 of the fourth lens on the image side satisfy: |SAG9| ≤ 0.4 mm, |SAG10| ≤ 0.4 mm.

7. The telephoto lens of claim 1, wherein, The refractive power Φ3 of the third lens satisfies: 0.03 < Φ3 < 0.

07.

8. The telephoto lens of claim 1, wherein, The distance H between the fourth lens and the prism 10 And the system focal length f' of the long-focus lens satisfies: 0.01<H 10 / f' < 0.

025.

9. The telephoto lens of claim 1, wherein, a distance H from an object-side vertex of the first lens to the prism 2-10 and an equivalent thickness H of the prism 11 satisfies: 0.35 ≤ (H 2-10 ) / H 11 ≤ 0.

45.

10. An electronic device, comprising: The long-focus lens comprises a lens assembly, a prism and an image plane in sequence from an object side to an image side; the lens assembly comprises a first lens, a second lens, a third lens and a fourth lens in sequence; the first lens has positive refractive power; the second lens has negative refractive power; the third lens has positive refractive power; the fourth lens has negative refractive power; the prism has an entrance surface, a first reflection surface, a first total reflection surface, a second total reflection surface, a second reflection surface and an exit surface, the entrance surface and the exit surface are oppositely arranged; the system focal length f' of the long-focus lens and the refractive power Φ1 of the first lens satisfy: 400 ≤ f' / φ1 ≤ 500.

Images