Telephoto lens and electronic equipment

Abstract

The invention discloses a telephoto lens and electronic equipment, the telephoto lens comprises a lens assembly, a turn-back prism and a compensation prism from an object side to an image side, and the lens assembly comprises a plurality of lenses arranged in sequence; the turn-back prism comprises a first working surface, a second working surface and a third working surface; light emitted by the lens assembly enters the turn-back prism from the first working face, is reflected to the first working face for the first time through the second working face, is reflected to the third working face for the second time through the first working face, and is emitted out through the third working face. The compensation prism comprises a fourth working surface and a fifth working surface; the light emitted by the turn-back prism enters the compensation prism from the fourth working surface and is emitted through the fifth working surface, so that the zero-view-field main light is vertically emitted to the imaging surface of the imaging chip, and the imaging chip is vertically arranged in the lens module. According to the telephoto lens and the electronic equipment, the height of the telephoto lens can be reduced, and lens miniaturization is achieved.

Description

Technical Field

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

[0002] With the development of multifunctionality of various electronic products, the camera function has become an essential function of many electronic products, such as smart phones and tablet computers with camera functions.

[0003] However, as users have increasingly higher requirements for lenses, telephoto lenses with longer back focal lengths generally have problems with the lenses being too high and protruding from the body, resulting in an unsightly appearance. Summary of the invention

[0004] In view of the above problems, an object of the present invention is to provide a telephoto lens and an electronic device, which can reduce the height of the telephoto lens and realize miniaturization of the lens. The present invention provides a telephoto lens, which comprises a lens assembly, a folding prism and a compensation prism from the object side to the image side; the lens assembly comprises a plurality of lenses arranged in sequence; the folding prism comprises a first working surface, a second working surface and a third working surface; the light emitted from the lens assembly enters the folding prism from the first working surface, is reflected to the first working surface by the second working surface for the first time, is reflected to the third working surface by the first working surface for the second time, and is emitted from the third working surface; the compensation prism comprises a fourth working surface and a fifth working surface; the light emitted from the folding prism enters the compensation prism from the fourth working surface, and is emitted from the fifth working surface, so that the main light of zero field of view is vertically incident on the imaging surface of an imaging chip, and the imaging chip is vertically arranged inside a lens module.

[0005] Optionally, the compensation prism is a wedge prism, and the fourth working surface and the fifth working surface form a wedge angle.

[0006] Optionally, the folding prism is a trapezoidal prism.

[0007] Optionally, the fourth working surface of the compensation prism coincides with the third working surface of the folding prism.

[0008] Optionally, the compensation prism and the folding prism form a combined prism.

[0009] Optionally, the Abbe coefficient Ab5 of the folding prism and the Abbe coefficient Ab6 of the compensation prism satisfy: Ab5>40, Ab6>40.

[0010] Optionally, the refractive index N5 of the folding prism and the refractive index N6 of the compensating prism satisfy: 0.1 <ABS(N5-N6)。

[0011] Optionally, a distance M1 from the lens surface of the lens assembly to the first working surface, and a distance M2 from the first working surface to the lower end point of the imaging surface satisfy: M1<5.1 mm, M2<5 mm, 0.5 <M1 / ML2<1.5。

[0012] Optionally, the focal length f' and the imaging circle diameter ImC of the telephoto lens satisfy: 1 <f’ / ImC<2.2。

[0013] Optionally, an included angle α1 between the first working surface and the second working surface satisfies: 25°≤α1≤45°.

[0014] Optionally, an included angle α2 between the fourth working surface and the fifth working surface satisfies: 8°≤α2≤25°.

[0015] Optionally, the lens assembly includes a first lens, a second lens, a third lens and a fourth lens, the first lens has positive optical power, and the second lens has negative optical power.

[0016] Optionally, the focal length f1 of the first lens and the focal length f2 of the second lens satisfy: 1≤|f2 / f1|≤2.

[0017] The present invention also provides an electronic device, comprising the above-mentioned telephoto lens.

[0018] The telephoto lens and electronic device provided by the present invention include a lens assembly, a folding prism and a compensating prism from the object side to the image side. The telephoto lens can be used to provide a telephoto lens with a large aperture and a large target surface by reasonably allocating the focal length, spacing and refractive index of each lens of the lens assembly, folding the back focus optical path of the lens by the folding prism, and correcting and deflecting the light by the compensating prism. The folding prism can be used to reduce the height of the telephoto lens, and the compensating prism can be used to vertically arrange an imaging chip, so as to facilitate the installation of the imaging chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

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

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

[0022] Figures 3 to 5 The axial aberration diagram, distortion diagram and MTF curve diagram of the telephoto lens of Example 1 are respectively shown.

[0023] Figure 6 A schematic structural diagram of a telephoto lens according to Embodiment 2 of the present application is shown.

[0024] Figures 7 to 9 The axial aberration diagram, distortion diagram and MTF curve diagram of the telephoto lens of Example 2 are respectively shown.

[0025] Fig.10 A schematic structural diagram of a telephoto lens according to Embodiment 3 of the present application is shown.

[0026] Figures 11 to 13 The axial aberration diagram, distortion diagram and MTF curve diagram of the telephoto lens of Example 3 are respectively shown. DETAILED DESCRIPTION

[0027] The aforementioned and other technical contents, features and effects of the present invention will be clearly presented in the following detailed description of the preferred embodiments with reference to the drawings. Through the description of the specific implementation methods, the technical means and effects adopted by the present invention to achieve the intended purpose can be more deeply and specifically understood. However, the attached drawings are only for reference and illustration purposes, and are not used to limit the present invention. Some well-known parts may not be shown. In each of the drawings, the same elements are represented by similar reference numerals. For the sake of clarity, the various parts in the drawings are not necessarily drawn strictly in accordance with the actual proportions.

[0028] It should be understood that the terms "first", "second", "third", "fourth", etc. are only used to distinguish components or circuits with similar properties, rather than indicating or implying relative importance or a specific order. The terms "include", "comprises", or any other variation thereof, are intended to cover non-exclusive inclusion, and may include other elements not explicitly listed in addition to those listed elements.

[0029] In the drawings, the thickness, size and shape of the lenses have been slightly exaggerated for ease of explanation. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are shown by way of example. That is, the shapes of the spherical or aspherical surfaces are not limited to the shapes of the spherical or aspherical surfaces shown in the drawings. The drawings are only examples 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 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 is called the object side of the lens, and the surface of each lens closest to the imaging plane IMG is called the image side of the lens.

[0031] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

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

[0033] Figure 1 A schematic structural diagram of a telephoto lens according to an embodiment of the present application is shown.

[0034] According to the telephoto lens of the exemplary embodiment of the present application, from the object side to the image side, it includes a lens assembly, a folding prism P1 and a compensation prism P2, and the lens assembly includes a plurality of lenses arranged in sequence; the folding prism P1 includes a first working surface, a second working surface and a third working surface; the light emitted from the lens assembly is incident on the folding prism P1 from the first working surface, is reflected for the first time to the first working surface by the second working surface, is reflected for the second time to the third working surface by the first working surface, and is emitted from the third working surface; the compensation prism P2 includes a fourth working surface and a fifth working surface; the light emitted from the folding prism P1 is incident on the compensation prism P2 from the fourth working surface, and is emitted from the fifth working surface, so that the main light of zero field of view is vertically incident on the imaging surface IMG of the imaging chip, wherein the imaging chip is vertically arranged inside the lens module.

[0035] Specifically, the lens assembly receives object light and realizes telephoto imaging by reasonably allocating the focal length, spacing and refractive index of multiple lenses of the lens assembly. The light emitted by the lens assembly enters the folding prism P1 from the first working surface, and the folding prism P1 can change the original straight line direction of the light, and the light is reflected twice inside the folding prism P1, that is, the first reflection occurs on the second working surface and the second reflection occurs on the first working surface, then the lens back focus optical path can be folded inside the folding prism P1, so that the light emitted from the folding prism P1 can reach the imaging surface IMG through a smaller optical path, which correspondingly shortens the lens back focus length. The light emitted from the folding prism P1 enters the compensation prism P2 from the fourth working surface, and the compensation prism P2 can correct and deflect the light, that is, the direction of the light will be deflected when it enters the fourth working surface and when it exits the compensation prism P2 at the fifth working surface, and finally the zero-field main light is vertically incident on the imaging surface IMG of the imaging chip. The imaging chip can be vertically arranged inside the lens module. If there is no compensation prism P2 for correction and polarization, the imaging surface IMG is often arranged at an angle, which will not be convenient for the installation of the imaging chip inside the lens module. In addition, the prism arrangement of this embodiment only reflects the light twice, because if it is reflected only once, although the direction of the light will be changed, it still occupies a longer space in the direction after the reflection to be used as the rear focus optical path of the lens, making the fuselage larger. If it is reflected more than three times, more than three reflecting surfaces need to be provided, and the prism structure is more complicated and will occupy a larger space, making the fuselage larger. Therefore, the telephoto lens of this embodiment can be used to provide a telephoto lens with a large aperture and a large target surface by reasonably allocating the optical focal length, spacing and refractive index of each lens of the lens assembly, folding the rear focal optical path of the lens by the folding prism P1, and correcting and deflecting the light by the compensating prism P2. The height of the telephoto lens can be lowered by using the folding prism P1, and the imaging chip can be set vertically by using the compensating prism P2, which is convenient for installing the imaging chip.

[0036] In an exemplary embodiment, according to the telephoto lens of the present application, the compensation prism P2 is a wedge-shaped prism, and the fourth working surface and the fifth working surface form a wedge angle. If the compensation prism P2 is a wedge-shaped prism, the fourth working surface and the fifth working surface can be used as two planes forming the wedge angle, which has a simple structure and can achieve light deflection, so that the zero-field main light is vertically incident on the imaging surface IMG of the imaging chip, which facilitates the imaging chip to be installed in a vertical setting inside the lens module.

[0037] In an exemplary embodiment, according to the telephoto lens of the present application, the folding prism P1 is a trapezoidal prism. If the folding prism P1 is a wedge-shaped prism, the second working surface and the third working surface can serve as the waist of the trapezoidal prism. The upper and lower bases of the trapezoidal prism are parallel to each other, which is easy to install and fix. However, the present invention is not limited to this, and the folding prism P1 can also be a prism of other shapes, such as a triangular prism.

[0038] In an exemplary embodiment, according to the telephoto lens of the present application, the folding prism P1 is an isosceles trapezoidal prism. The folding prism P1 is an isosceles wedge-shaped prism, so there is no need to distinguish the two waists of the trapezoidal prism, which is convenient for installation.

[0039] In an exemplary embodiment, according to the telephoto lens of the present application, the second working surface can be coated with a reflective film. Thus, when the light is reflected by the second working surface, it can be ensured that the light can be completely reflected, reducing the risk of the light being refracted out of the return prism P1 when the light is first reflected by the second working surface. It is understandable that the first working surface can also be coated with a reflective film to ensure that the light can be completely reflected, reducing the risk of the light being refracted out of the return prism P1 when the light is secondly reflected by the first working surface.

[0040] In an exemplary embodiment, according to the telephoto lens of the present application, the folding prism P1 may be provided with a cut corner or a rounded corner, etc. By cutting or rounding the corner, the planar length of the folding prism P1, such as the lateral length of the first working surface, can be reduced, thereby reducing the overall lateral length of the folding prism P1, thereby saving the internal space of the lens module, helping to improve the reliability of the module and reduce stray light.

[0041] In an exemplary embodiment, according to the telephoto lens of the present application, the fourth working surface of the compensation prism P2 overlaps with the third working surface of the folding prism P1. That is, the compensation prism P2 and the folding prism P1 are in a surface overlap relationship, and the two can be glued together or separated.

[0042] In an exemplary embodiment, according to the telephoto lens of the present application, the compensation prism P2 and the folding prism P1 form a combined prism. Figure 1 As shown, not only does the fourth working surface of the compensation prism P2 coincide with the third working surface of the return prism P1, but the length of the fourth working surface of the compensation prism P2 is also equal to the length of the third working surface of the return prism P1. Therefore, the compensation prism P2 can be used as a compensation element on the third working surface of the return prism P1. The compensation prism P2 and the return prism P1 can form a combined prism, which can be used for light offset compensation and is easy to install.

[0043] In an exemplary embodiment, according to the telephoto lens of the present application, Ab5>40 and Ab6>40 may be satisfied, wherein the Abbe coefficient of the folding prism P1 is Ab5 and the Abbe coefficient of the compensating prism P2 is Ab6. Satisfying Ab5>40 and Ab6>40, by controlling the magnitude of the Abbe coefficient Ab5 of the folding prism P1 and the magnitude of the Abbe coefficient Ab6 of the compensating prism P2, it is possible to avoid large chromatic aberration introduced by the folding prism P1 and the compensating prism P2, so that the telephoto lens has good imaging quality.

[0044] In an exemplary embodiment, for the telephoto lens according to the present application, 0.1 < ABS(N5 - N6) can be satisfied, where N5 is the refractive index of the retroflection prism P1 and N6 is the refractive index of the compensation prism P2. By satisfying 0.1 < ABS(N5 - N6), the difference between the refractive index N5 of the retroflection prism P1 and the refractive index N6 of the compensation prism P2 is controlled, and a large refractive index difference can cause a large deflection angle of light, which is beneficial to achieving horizontal light emission.

[0045] In an exemplary embodiment, for the telephoto lens according to the present application, M1 < 5.1 mm, M2 < 5 mm, and 0.5 < M1 / M2 < 1.5 can be satisfied, where M1 is the distance from the lens surface of the lens assembly to the first working surface, and M2 is the distance from the first working surface to the lower endpoint of the imaging surface. By satisfying M1 < 5.1 mm, M2 < 5 mm, and 0.5 < M1 / M2 < 1.5, by controlling the distance M1 from the lens surface of the lens assembly to the first working surface and the distance M2 from the first working surface to the lower endpoint of the imaging surface, it is beneficial to control the system height within a reasonable range, and thus beneficial to lens miniaturization.

[0046] In an exemplary embodiment, for the telephoto lens according to the present application, 1 < f’ / ImC < 2.2 can be satisfied, where f’ is the focal length of the telephoto lens and ImC is the imaging circle diameter. By satisfying 1 < f’ / ImC < 2.2, by controlling the ratio of the focal length f’ of the telephoto lens and the imaging circle diameter ImC within a limited range, it is possible to better balance a large aperture and a small field of view angle.

[0047] In an exemplary embodiment, for the telephoto lens according to the present application, 25° ≤ α1 ≤ 45° can be satisfied, where α1 is the angle between the first working surface and the second working surface of the retroflection prism P1. By satisfying 25° ≤ α1 ≤ 45°, by controlling the angle α1 between the first working surface and the second working surface of the retroflection prism P1, it is beneficial to ensure that the retroflection prism P1 has a smaller thickness, and thus beneficial to lens miniaturization.

[0048] In an exemplary embodiment, for the telephoto lens according to the present application, 8° ≤ α2 ≤ 25° can be satisfied, where α2 is the angle between the fourth working surface and the fifth working surface of the compensation prism P2. By satisfying 8° ≤ α2 ≤ 25°, by controlling the angle α2 between the fourth working surface and the fifth working surface of the compensation prism P2, it is beneficial to enable the compensation prism P2 to have a certain optical path difference up and down.

[0049] In an exemplary embodiment, for the telephoto lens according to the present application, 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 a positive optical power, and the second lens L2 has a negative optical power. The first lens L1 has a positive optical power for converging light rays. The second lens L2 has a negative optical power for aberration correction. By combining the convex or concave surfaces of multiple lenses, various aberrations can be balanced to obtain a clear image.

[0050] In one exemplary embodiment, for the telephoto lens according to the present application, 1≤|f2 / f1|≤2 can be satisfied, where f1 is the focal length of the first lens L1 and f2 is the focal length of the second lens L2. Satisfying 1≤|f2 / f1|≤2, by controlling the focal lengths f1 of the first lens L1 and f2 of the second lens L2, it is beneficial for aberration correction and high resolution can be achieved.

[0051] In one exemplary embodiment, for the telephoto lens according to the present application, 0.1<f1 / f’<1 can be satisfied, where f1 is the focal length of the first lens L1 and f’ is the focal length of the telephoto lens. Satisfying 0.1<f1 / f’<1, by controlling the ratio of the focal length f1 of the first lens L1 to the focal length f’ of the telephoto lens, it is beneficial for the first lens L1 to bear the main optical power of the optical system, which is beneficial for aberration correction and high resolution can be achieved.

[0052] In one exemplary embodiment, for the telephoto lens according to the present application, 0.1<|f2 / f’|<2 can be satisfied, where f2 is the focal length of the second lens L2 and f’ is the focal length of the telephoto lens. Satisfying 0.1<|f2 / f’|<2, 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 for the second lens L2 to maintain a weak optical power of the lens, avoiding large aberrations and enabling the telephoto lens to have good imaging quality.

[0053] In one exemplary embodiment, for the telephoto lens according to the present application, 1<|f3 / f’|<5 can be satisfied, where f3 is the focal length of the third lens L3 and f’ is the focal length of the telephoto lens. Satisfying 1<|f3 / f’|<5, by controlling the ratio of the focal length f3 of the third lens L3 to the focal length f’ of the telephoto lens, it is beneficial for the third lens L3 to maintain a weak optical power of the lens, avoiding large aberrations and enabling the telephoto lens to have good imaging quality.

[0054] In one exemplary embodiment, for the telephoto lens according to the present application, 1 < |f4 / f’| < 35 can be satisfied, where the focal length of the fourth lens L4 is f4 and the focal length of the telephoto lens is f’. Satisfying 1 < |f4 / f’| < 35 is conducive to keeping the lens weak refractive power of the fourth lens L4 by controlling the ratio of the focal length f4 of the fourth lens L4 to the focal length f’ of the telephoto lens, avoiding large aberrations, and enabling the telephoto lens to have good imaging quality.

[0055] In one exemplary embodiment, for the telephoto lens according to the present application, 0.05 < H3 / f’ < 0.15 can be satisfied, where the thickness of the first lens L1 is H3 and the focal length of the telephoto lens is f’. Satisfying 0.05 < H3 / f’ < 0.15 can avoid difficult processing due to too thick lens by controlling the ratio of the thickness H3 of the first lens L1 to the focal length f’ of the telephoto lens within a certain range.

[0056] In one exemplary embodiment, for the telephoto lens according to the present application, 1.5 < Ab1 / Ab2 < 2.5 can be satisfied, where the Abbe number of the first lens L1 is Ab1 and the Abbe number of the second lens L2 is Ab2. Satisfying 1.5 < Ab1 / Ab2 < 2.5 is conducive to chromatic aberration correction by controlling the ratio of the Abbe number Ab1 of the first lens L1 to the Abbe number Ab2 of the second lens L2 within a certain range, enabling the telephoto lens to have good imaging quality.

[0057] In an exemplary embodiment, for the telephoto lens according to the present application, the telephoto lens further includes a stop STO, and the stop STO can be disposed on the object side of the first lens L1 or between adjacent lenses.

[0058] In an exemplary embodiment, for the telephoto lens according to the present application, 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. In one exemplary embodiment, for the telephoto lens according to the present application, the filter IR can be disposed between the fifth working surface of the compensation prism P2 and the imaging surface IMG, but the present invention is not limited thereto, and the filter IR can also be disposed at other positions, such as between the lens assembly and the first working surface of the folding prism P1, etc.

[0059] Based on the same inventive concept, for the electronic device according to the exemplary embodiment of the present application, the electronic device includes 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. For the implementation of this electronic device, reference can be made to the embodiments of the telephoto lens, and repeated parts will not be elaborated.

[0060] However, those skilled in the art should understand that, without departing from the technical solution claimed in the present 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 four lenses are described as an example in the embodiments, the optical imaging lens is not limited to including four lenses. If necessary, the optical imaging lens may also include other numbers of lenses.

[0061] Specific embodiments of the telephoto lens applicable to the above-mentioned embodiments are further described below with reference to the accompanying drawings.

[0062] Example 1 The following reference Figure 2 A telephoto lens according to Embodiment 1 of the present application is described. Figure 2 A schematic structural diagram of a telephoto lens according to Embodiment 1 of the present application is shown.

[0063] The telephoto lens of Example 1 includes a lens assembly, a folding prism P1 and a compensation prism P2 in order from the object side to the image side. The lens assembly may include a first lens L1, a second lens L2, a third lens L3 and a fourth lens L4. The aperture STO may be arranged on the object side of the first lens L1. The filter IR may be arranged between the compensation prism P2 and the imaging surface IMG.

[0064] The first lens L1 has positive optical power, and its object side surface is convex, and its image side surface is convex. The second lens L2 has negative optical power, and its object side surface is convex, and its image side surface is concave. The third lens L3 has negative optical power, and its object side surface is concave, and its image side surface is convex. The fourth lens L4 has positive optical power, and its object side surface is convex, and its image side surface is concave. The filter IR has an object side surface and an image side surface. The reentrant prism P1 has a first working surface, a second working surface, and a third working surface. The compensation prism P2 has a fourth working surface and a fifth working surface. The light from the object passes through the aperture STO, the first lens L1, the second lens L2, the third lens L3 and the fourth lens L4 in sequence, and then enters the return prism P1 from the first working surface, is reflected for the first time at the second working surface, is reflected for the second time at the first working surface, is emitted through the third working surface, and then enters the compensation prism P2 from the fourth working surface, is emitted through the fifth working surface, passes through the filter IR, and is finally imaged on the imaging surface IMG.

[0065] Table 1 shows basic parameters of the telephoto lens of Example 1, wherein the curvature radius, thickness and focal length are all in millimeters (mm).

[0066] Table 1:

[0067] Among them, L1 R1 represents the object side surface of the first lens L1, L1 R2 represents the image side surface of the first lens L1, L2 R1 represents the object side surface of the second lens L2, L2 R2 represents the image side surface of the second lens L2, L3 R1 represents the object side surface of the third lens L3, L3 R2 represents the image side surface of the third lens L3, L4 R1 represents the object side surface of the fourth lens L4, L4 R2 represents the image side surface of the fourth lens L4, P1 R1 represents the object side surface of the return prism P1, that is, the first working surface, P1 R2 represents the image side surface of the return prism P1, that is, the third working surface, P2 R1 represents the object side surface of the compensation prism P2, that is, the fourth working surface, P2 R2 represents the image side surface of the compensation prism P2, that is, the fifth working surface, IR R1 represents the object side surface of the filter IR, and IR R2 represents the image side surface of the filter IR.

[0068] In Embodiment 1, the object side surface and the image side surface of any lens among the first lens L1 to the fourth lens L4 are both even-order aspherical surfaces, and the surface shape of each aspherical lens can be defined by but not limited to the following aspherical surface formula: …… ... Wherein, Z represents the height in the optical axis direction, c is the inverse of the surface radius, k is the cone coefficient, r is the diameter in the radial direction; α represents the aspheric coefficient, α1 represents the aspheric coefficient A2, α2 represents the aspheric coefficient A4... Table 2 shows the high-order coefficients A2, A4, A6, A8, A10, A12, A14 and A16 that can be used for each aspheric mirror surface in Example 1.

[0069] Table 2:

[0070] In Example 1, the focal length of the telephoto lens is 13.3 mm, the aperture of the telephoto lens is 2.4, the imaging circle diameter of the telephoto lens is 8.16 mm, and the field of view angle of the telephoto lens is 33°. The angle between the first working surface and the second working surface may be α1=30.0°. The angle between the fourth working surface and the fifth working surface may be α2=11.5°. The focal length of the first lens L1 is f1=6.624 mm, the focal length of the second lens L2 is f2=-11.664 mm, and the relationship between the focal length f1 of the first lens L1 and the focal length f2 of the second lens L2 is |f2 / f1|=1.761. The relationship between the focal length f1 of the first lens L1 and the focal length f' of the telephoto lens is f1 / f'=0.498. The relationship between the focal length f2 of the second lens L2 and the focal length f' of the telephoto lens is |f2 / f'|=0.877. The relationship between the focal length f3 of the third lens L3 and the focal length f' of the telephoto lens is |f3 / f'|=2.932. The relationship between the focal length f4 of the fourth lens L4 and the focal length f' of the telephoto lens is |f4 / f'|=5.056. The relationship between the thickness H3 of the first lens L1 and the focal length f' of the telephoto lens is H3 / f'=0.099. The relationship between the Abbe coefficient Ab1 of the first lens L1 and the Abbe coefficient Ab2 of the second lens L2 is Ab1 / Ab2=2.188. The Abbe coefficient Ab5 of the folding prism P1 is 64.2, and the Abbe coefficient Ab6 of the compensation prism P2 is 54.7. The relationship between the refractive index N5 of the folding prism P1 and the refractive index N6 of the compensation prism P2 is ABS(N5-N6)=0.140. The relationship between the distance M1 from the lens surface of the lens assembly to the first working surface and the distance M2 from the first working surface to the lower end point of the imaging surface is M1=4.990, M2=3.540, M1 / M2=1.41. The relationship between the focal length f' of the telephoto lens and the imaging circle diameter ImC is f' / ImC=1.630.

[0071] Figure 3 The axial aberration diagram of the telephoto lens of Example 1 is shown, which illustrates the focus deviation formed on the focal plane by light of different wavelengths along the direction of the optical axis when the pupil radius is 2.7700 mm. The lateral aberration is less than 0.04 mm, and the aberration correction is good. Figure 4 The distortion diagram of the telephoto lens of Example 1 is shown, and the optical distortion is less than 0.5%, which is very small. Figure 5 The MTF curve of the telephoto lens of Example 1 is shown, and the MTF (Modulation Transfer Function) curve shows the transmission of image details (i.e., image contrast) of the imaging system at different spatial frequencies. The MTF value is greater than 0.5 at a spatial frequency of 125lp / mm, which has good resolution. Figures 3 to 5It can be seen that the telephoto lens provided in Example 1 can achieve good imaging quality.

[0072] Example 2 The following reference Figure 6 A telephoto lens according to Embodiment 2 of the present application is described. In this embodiment, for the sake of brevity, some descriptions similar to Embodiment 1 are omitted. Figure 6 A schematic structural diagram of a telephoto lens according to Embodiment 2 of the present application is shown.

[0073] The telephoto lens of Example 2 includes a lens assembly, a folding prism P1 and a compensation prism P2 in order from the object side to the image side. The lens assembly may include a first lens L1, a second lens L2, a third lens L3 and a fourth lens L4. The aperture STO may be arranged on the object side of the first lens L1. The filter IR may be arranged between the compensation prism P2 and the imaging surface IMG.

[0074] The first lens L1 has positive optical power, and its object side surface is convex, and its image side surface is convex. The second lens L2 has negative optical power, and its object side surface is convex, and its image side surface is concave. The third lens L3 has negative optical power, and its object side surface is concave, and its image side surface is convex. The fourth lens L4 has negative optical power, and its object side surface is convex, and its image side surface is concave. The filter IR has an object side surface and an image side surface. The reentrant prism P1 has a first working surface, a second working surface, and a third working surface. The compensation prism P2 has a fourth working surface and a fifth working surface. The light from the object passes through the aperture STO, the first lens L1, the second lens L2, the third lens L3 and the fourth lens L4 in sequence, and then enters the return prism P1 from the first working surface, is reflected for the first time at the second working surface, is reflected for the second time at the first working surface, is emitted through the third working surface, and then enters the compensation prism P2 from the fourth working surface, is emitted through the fifth working surface, passes through the filter IR, and is finally imaged on the imaging surface IMG.

[0075] Table 3 shows basic parameters of the telephoto lens of Example 2, where the curvature radius, thickness and focal length are all in millimeters (mm).

[0076] Table 3:

[0077] Table 4 shows the high-order coefficients of each aspherical mirror surface that can be used in Example 2, wherein each aspherical surface shape can be defined by the formula (1) given in the above-mentioned Example 1.

[0078] Table 4:

[0079] In Example 2, the focal length of the telephoto lens is 13.3 mm, the aperture of the telephoto lens is 2.4, the imaging circle diameter of the telephoto lens is 8.16 mm, and the field of view angle of the telephoto lens is 33°. The angle between the first working surface and the second working surface may be α1=30.0°. The angle between the fourth working surface and the fifth working surface may be α2=11.5°. The focal length of the first lens L1 is f1=5.870 mm, the focal length of the second lens L2 is f2=--8.528 mm, and the relationship between the focal length f1 of the first lens L1 and the focal length f2 of the second lens L2 is |f2 / f1|=1.453. The relationship between the focal length f1 of the first lens L1 and the focal length f' of the telephoto lens is f1 / f'=0.441. The relationship between the focal length f2 of the second lens L2 and the focal length f' of the telephoto lens is |f2 / f'|=0.641. The relationship between the focal length f3 of the third lens L3 and the focal length f' of the telephoto lens is |f3 / f'|=1.461. The relationship between the focal length f4 of the fourth lens L4 and the focal length f' of the telephoto lens is |f4 / f'|=31.110. The relationship between the thickness H3 of the first lens L1 and the focal length f' of the telephoto lens is H3 / f'=0.099. The relationship between the Abbe coefficient Ab1 of the first lens L1 and the Abbe coefficient Ab2 of the second lens L2 is Ab1 / Ab2=2.188. The Abbe coefficient Ab5 of the folding prism P1 is 64.2, and the Abbe coefficient Ab6 of the compensation prism P2 is 54.7. The relationship between the refractive index N5 of the folding prism P1 and the refractive index N6 of the compensation prism P2 is ABS(N5-N6)=0.140. The relationship between the distance M1 from the lens surface of the lens assembly to the first working surface and the distance M2 from the first working surface to the lower end point of the imaging surface is M1=4.970, M2=3.540, and M1 / M2=1.40. The relationship between the focal length f' of the telephoto lens and the imaging circle diameter ImC is f' / ImC=1.630.

[0080] Figure 7 The axial aberration diagram of the telephoto lens of Example 2 is shown, which illustrates the focus deviation formed on the focal plane by light of different wavelengths along the direction of the optical axis when the pupil radius is 2.7700 mm. The lateral aberration is less than 0.04 mm, and the aberration correction is good. Figure 8 The distortion diagram of the telephoto lens of Example 2 is shown, and the optical distortion is less than 0.5%, which is very small. Fig. 9 The MTF curve of the telephoto lens of Example 2 is shown, and the MTF (Modulation Transfer Function) curve shows the transmission of image details (i.e., image contrast) of the imaging system at different spatial frequencies. The MTF value is greater than 0.5 at a spatial frequency of 125lp / mm, which has good resolution. Figures 7 to 9It can be seen that the telephoto lens provided in Example 2 can achieve good imaging quality.

[0081] Example 3 The following reference Fig.10 A telephoto lens according to Embodiment 3 of the present application is described. In this embodiment, for the sake of brevity, some descriptions similar to Embodiment 1 are omitted. Fig.10 A schematic structural diagram of a telephoto lens according to Embodiment 3 of the present application is shown.

[0082] The telephoto lens of Example 3 includes a lens assembly, a folding prism P1 and a compensation prism P2 in order from the object side to the image side. The lens assembly may include a first lens L1, a second lens L2, a third lens L3 and a fourth lens L4. The aperture STO may be arranged on the object side of the first lens L1. The filter IR may be arranged between the compensation prism P2 and the imaging surface IMG.

[0083] The first lens L1 has positive optical power, and its object side surface is convex, and its image side surface is convex. The second lens L2 has negative optical power, and its object side surface is convex, and its image side surface is concave. The third lens L3 has positive optical power, and its object side surface is concave, and its image side surface is convex. The fourth lens L4 has negative optical power, and its object side surface is convex, and its image side surface is concave. The filter IR has an object side surface and an image side surface. The reentrant prism P1 has a first working surface, a second working surface, and a third working surface. The compensation prism P2 has a fourth working surface and a fifth working surface. The light from the object passes through the aperture STO, the first lens L1, the second lens L2, the third lens L3 and the fourth lens L4 in sequence, and then enters the return prism P1 from the first working surface, is reflected for the first time at the second working surface, is reflected for the second time at the first working surface, is emitted through the third working surface, and then enters the compensation prism P2 from the fourth working surface, is emitted through the fifth working surface, passes through the filter IR, and is finally imaged on the imaging surface IMG.

[0084] Table 5 shows basic parameters of the telephoto lens of Example 3, where the curvature radius, thickness and focal length are all in millimeters (mm).

[0085] Table 5:

[0086] Table 6 shows the high-order coefficients of each aspherical mirror surface that can be used in Example 3, wherein each aspherical surface shape can be defined by the formula (1) given in the above Example 1.

[0087] Table 6:

[0088] In Example 3, the focal length of the telephoto lens is 13.3 mm, the aperture of the telephoto lens is 2.4, the imaging circle diameter of the telephoto lens is 8.16 mm, and the field of view angle of the telephoto lens is 33°. The angle between the first working surface and the second working surface may be α1=30.0°. The angle between the fourth working surface and the fifth working surface may be α2=11.5°. The focal length of the first lens L1 is f1=6.252 mm, the focal length of the second lens L2 is f1=-9.390 mm, and the relationship between the focal length f1 of the first lens L1 and the focal length f2 of the second lens L2 is |f2 / f1|=1.502. The relationship between the focal length f1 of the first lens L1 and the focal length f' of the telephoto lens is f1 / f'=0.470. The relationship between the focal length f2 of the second lens L2 and the focal length f' of the telephoto lens is |f2 / f'|=0.706. The relationship between the focal length f3 of the third lens L3 and the focal length f' of the telephoto lens is |f3 / f'|=3.376. The relationship between the focal length f4 of the fourth lens L4 and the focal length f' of the telephoto lens is |f4 / f'|=3.143. The relationship between the thickness H3 of the first lens L1 and the focal length f' of the telephoto lens is H3 / f'=0.100. The relationship between the Abbe coefficient Ab1 of the first lens L1 and the Abbe coefficient Ab2 of the second lens L2 is Ab1 / Ab2=2.188. The Abbe coefficient Ab5 of the folding prism P1 is 64.2, and the Abbe coefficient Ab6 of the compensation prism P2 is 54.7. The relationship between the refractive index N5 of the folding prism P1 and the refractive index N6 of the compensation prism P2 is ABS(N5-N6)=0.140. The relationship between the distance M1 from the lens surface of the lens assembly to the first working surface and the distance M2 from the first working surface to the lower end point of the imaging surface is M1=5.050, M2=3.540, M1 / M2=1.43. The relationship between the focal length f' of the telephoto lens and the imaging circle diameter ImC is f' / ImC=1.630.

[0089] Fig.11 The axial aberration diagram of the telephoto lens of Example 3 is shown, which illustrates the focus deviation formed on the focal plane by light of different wavelengths along the direction of the optical axis when the pupil radius is 2.7700 mm. The lateral aberration is less than 0.05 mm, and the aberration correction is good. Fig.12 The distortion diagram of the telephoto lens of Example 3 is shown, and the optical distortion is less than 0.5%, which is very small. Fig.13 The MTF curve of the telephoto lens of Example 3 is shown, and the MTF (Modulation Transfer Function) curve shows the transmission of image details (i.e., image contrast) of the imaging system at different spatial frequencies. The MTF value is greater than 0.5 at a spatial frequency of 125lp / mm, which has good resolution. Figures 11 to 13It can be seen that the telephoto lens provided in Example 3 can achieve good imaging quality.

[0090] In summary, Example 1, Example 2 and Example 3 respectively satisfy the relationship shown in Table 7.

[0091] Table 7:

[0092] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a 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 above features are replaced with (but not limited to) technical features with similar functions disclosed in the present application.

Claims

1. A telephoto lens, characterized in that: From the object side to the image side includes: A lens assembly, the lens assembly comprising a plurality of lenses arranged in sequence; A folding prism, the folding prism comprising a first working surface, a second working surface and a third working surface; the light emitted by the lens assembly enters the folding prism from the first working surface, is reflected by the second working surface to the first working surface for the first time, is reflected by the first working surface to the third working surface for the second time, and is emitted from the third working surface; A compensation prism, wherein the compensation prism comprises a fourth working surface and a fifth working surface; the light emitted from the folding prism is incident from the fourth working surface to the compensation prism, and is emitted through the fifth working surface, so that the zero-field main light is vertically incident on the imaging surface of the imaging chip, and the imaging chip is vertically arranged inside the lens module.

2. The telephoto lens according to claim 1, characterized in that: The Abbe coefficient Ab5 of the folding prism and the Abbe coefficient Ab6 of the compensation prism satisfy: Ab5>40, Ab6>40.

3. The telephoto lens according to claim 1, characterized in that: The refractive index N5 of the folding prism and the refractive index N6 of the compensating prism satisfy: 0.1 <ABS(N5-N6)。 4. The telephoto lens according to claim 1, wherein: The distance M1 from the lens surface of the lens assembly to the first working surface, and the distance M2 from the first working surface to the lower end point of the imaging surface satisfy: M1<5.1mm, M2<5mm, 0.5 <M1 / M2<1.5。 5. The telephoto lens according to claim 1, characterized in that: The focal length f' and imaging circle diameter ImC of the telephoto lens satisfy: 1 <f’ / ImC<2.2。 6. The telephoto lens according to claim 1, wherein: An included angle α1 between the first working surface and the second working surface satisfies: 25°≤α1≤45°.

7. The telephoto lens according to claim 1, wherein: An included angle α2 between the fourth working surface and the fifth working surface satisfies: 8°≤α2≤25°.

8. The telephoto lens according to claim 1, wherein: The lens assembly includes a first lens, a second lens, a third lens and a fourth lens, the first lens has positive optical power, and the second lens has negative optical power.

9. The telephoto lens according to claim 8, characterized in that: The focal length f1 of the first lens and the focal length f2 of the second lens satisfy: 1≤|f2 / f1|≤2.

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

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