Mobile phone telephoto lens with reduced height

Abstract

The invention discloses a mobile phone telephoto lens with reduced height. The mobile phone telephoto lens with reduced height sequentially comprises a first lens, a second lens, a third lens, a fourth lens, a prism and an image surface from an object space to an image space, wherein the first lens has positive focal power; the second lens has positive focal power; the third lens has positive focal power; the fourth lens has negative focal power; the prism is provided with an incident plane, a first reflection plane, a total reflection plane, a second reflection plane and an emergent plane, and light emitted by the fourth lens enters the prism from the incident plane, is reflected at least once through the first reflection plane, the total reflection plane and the second reflection plane and then is emitted to the image plane through the emergent plane. According to the mobile phone telephoto lens with the reduced height, the large aperture, the small size, the long focal length and the high imaging quality of the lens can be realized.

Description

Technical Field

[0001] The invention relates to the technical field of optical imaging, and in particular to a mobile phone telephoto lens with a reduced height. Background Art

[0002] With the development of mobile phone camera modules, the use scenarios of mobile phone telephoto lenses have gradually increased, and telephoto has become an indispensable part of mobile phone telephoto lenses. However, due to the space limitations of mobile phones and the need for telephoto optical distance, conventional periscope lenses are difficult to meet the requirements of telephoto lenses for focal length, large aperture, and small size. The longer the focal length, the larger the aperture and the thicker the mobile phone module required, making it impossible to use telephoto and large aperture lenses in mobile phones. Summary of the invention

[0003] In view of the above problems, the object of the present invention is to provide a mobile phone telephoto lens with a reduced height, which can achieve a large aperture, small size, long focal length and high imaging quality of the lens. The present invention provides a mobile phone telephoto lens with a reduced height, comprising a first lens, a second lens, a third lens, a fourth lens, a prism and an image plane; wherein the first lens has a positive focal length; the second lens has a positive focal length; the third lens has a positive focal length; the fourth lens has a negative focal length; the prism has an incident surface, a first reflection surface, a total reflection surface, a second reflection surface and an exit surface; the light emitted by the fourth lens enters the prism from the incident surface, is reflected at least once by the first reflection surface, the total reflection surface and the second reflection surface, and then is emitted to the image plane through the exit surface.

[0004] Optionally, the light emitted from the fourth lens is incident into the prism through the incident surface along the first optical axis direction, is reflected by the first reflection surface to reach the total reflection surface along the second optical axis direction, is then reflected by the total reflection surface to reach the second reflection surface along the third optical axis direction, is then reflected by the second reflection surface to reach the exit surface along the fourth optical axis direction, and is then emitted through the exit surface to the image plane.

[0005] Optionally, the center thickness CT1 of the first lens, the center thickness CT2 of the second lens, the center thickness CT3 of the third lens, the center thickness CT4 of the fourth lens, the space gap T1 between the first lens and the second lens, the space gap T2 between the second lens and the third lens, and the space gap T3 between the third lens and the fourth lens satisfy: CT1+CT2+CT3+CT4+T1+T2+T3<3.3mm.

[0006] Optionally, an air gap T4 between the fourth lens and the prism satisfies: 0.33 mm<T4<0.55 mm.

[0007] Optionally, the effective focal length f of the mobile phone telephoto lens and the distance BFL from the image side of the fourth lens to the image plane satisfy: 0.7<f / BFL<1.

[0008] Optionally, the effective focal length f of the mobile phone telephoto lens, the effective focal length f2 of the second lens, and the effective focal length f4 of the fourth lens satisfy: 0<((f / f4)-(f / f2))<3.

[0009] Optionally, a thickness CT5 of the prism satisfies: 11 mm<CT5<14 mm.

[0010] Optionally, the maximum effective diameter DT11 of the first lens on the object side, the maximum effective diameter DT12 of the first lens on the image side, the maximum effective diameter DT21 of the second lens on the object side, and the maximum effective diameter DT22 of the second lens on the image side satisfy: 19<(DT11+DT21) / (DT12 / DT22)<21.

[0011] Optionally, the thickness CT6 of the prism after folding the light path and the total length L1 of the prism after light conversion satisfy: 0.2<CT6 / L1<0.3.

[0012] The reduced height mobile phone telephoto lens provided by the present invention can be used to achieve focusing imaging within the range of 25 cm to infinity by reasonably allocating the optical focal length, and can be used to achieve good imaging quality within the range of 25 cm and infinity. In addition, the multi-lens and prism are combined into an L-shaped periscope structure to fully utilize the space, thereby realizing a large aperture, small size, and long focal length telephoto optical lens design scheme. The optical scheme has a small shoulder height and can be adapted to a portable folding machine. The reduced height mobile phone telephoto lens provided by the present invention can be used to achieve the following beneficial effects: 1) A 72mm equivalent focal length high-definition telephoto lens was designed to achieve good imaging quality at a large aperture of F2.6 from 25cm to infinity; 2) The optical solution has a shoulder height of 3.08mm, which is perfectly suitable for the design of thin and light folding machines; 3) The height of the lens body is 7.5mm, making full use of the space of the decorative part on the back cover of the mobile phone. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] 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.

[0014] Figure 1 A lens equivalent structure diagram of a mobile phone telephoto lens with a reduced height according to an embodiment of the present application is shown.

[0015] Figure 2 A lens equivalent structure diagram of a mobile phone telephoto lens with a reduced height according to an embodiment of the present application is shown.

[0016] Figure 3 A lens equivalent structure diagram of a mobile phone telephoto lens with a reduced height according to Example 1 of the present application is shown.

[0017] Figures 4 to 8 The MTF curve diagram, relative illumination and Y field of view diagram, distortion diagram, light fan diagram and vertical axis chromatic aberration diagram of the reduced height mobile phone telephoto lens of Example 1 are respectively shown.

[0018] Fig. 9 A lens equivalent structure diagram of a mobile phone telephoto lens with a reduced height according to Example 2 of the present application is shown.

[0019] Figures 10 to 14 The MTF curve diagram, relative illumination and Y field of view diagram, distortion diagram, light fan diagram and vertical axis chromatic aberration diagram of the reduced height mobile phone telephoto lens of Example 2 are respectively shown. DETAILED DESCRIPTION

[0020] 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.

[0021] 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.

[0022] In the drawings, the thickness, size and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical surfaces shown in the drawings are shown by way of example. That is, the shapes of the spherical surfaces are not limited to the shapes of the spherical surfaces shown in the drawings. The drawings are only examples and are not drawn strictly to scale.

[0023] 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 image plane is called the image side of the lens.

[0024] 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.

[0025] The features, principles and other aspects of the present application are described in detail below.

[0026] like Figure 1 As shown, according to the reduced height mobile phone telephoto lens of the exemplary embodiment of the present application, along the optical axis from the object side to the image side, it includes a first lens G1, a second lens G2, a third lens G3, a fourth lens G4, a prism G5 and an image plane IMG in sequence; wherein the first lens G1 has positive optical power; the second lens G2 has positive optical power; the third lens G3 has positive optical power; the fourth lens G4 has negative optical power; the prism G5 has an incident surface, a first reflection surface, a total reflection surface, a second reflection surface and an exit surface ( Figure 1 Not shown, please refer to Figure 2 ), the light emitted from the fourth lens G4 is incident on the prism G5 from the incident surface, is reflected at least once by the first reflection surface, the total reflection surface and the second reflection surface, and then is emitted to the image surface IMG through the exit surface.

[0027] In the reduced height mobile phone telephoto lens of this embodiment, the optical power of the first lens G1 to the fourth lens G4 follows the positive, positive, positive and negative arrangement, which is conducive to the correction of spherical aberration and chromatic aberration; the third lens G3 can be a biconcave lens, that is, its object side and image side are both concave. The light emitted by the fourth lens G4 enters the prism G5 from the incident surface, is reflected at least once by the first reflection surface, the total reflection surface and the second reflection surface, and then is emitted to the image surface IMG through the exit surface, so that the back focus optical path is folded inside the prism G5, shortening the back focus length of the lens to reduce the height of the camera. By reasonably allocating the optical power of each lens, it can be used to achieve focusing imaging within the range of 25cm to infinity of the 1 / 2.76″ telephoto lens, and can be used to achieve good imaging quality within the range of 25cm and infinity. By combining multiple lenses and prism G5 into an L-shaped periscope structure to fully utilize the space, a telephoto optical lens design scheme with a large aperture, small size and long focal length is realized. The optical scheme has a small shoulder height and can be adapted to a portable folding machine.

[0028] In an exemplary embodiment, reference may be made to Figure 2According to the reduced height mobile phone telephoto lens of the present application, the light emitted from the fourth lens G4 is incident on the prism G5 through the incident surface along the first optical axis direction, is reflected by the first reflection surface to reach the total reflection surface along the second optical axis direction, is then reflected by the total reflection surface to reach the second reflection surface along the third optical axis direction, is then reflected by the second reflection surface to reach the exit surface along the fourth optical axis direction, and is then emitted to the image surface IMG through the exit surface.

[0029] In one exemplary embodiment, according to the reduced height mobile phone telephoto lens of the present application, the angle θ1 between the first optical axis and the second optical axis satisfies 0°<θ1<90°; the angle θ2 between the second optical axis and the third optical axis satisfies 90°<θ2<180°; the angle θ3 between the third optical axis and the fourth optical axis satisfies 0°<θ3<90°. And in one exemplary embodiment, according to the reduced height mobile phone telephoto lens of the present application, the first optical axis and the fourth optical axis are in a parallel relationship.

[0030] In one exemplary embodiment, according to the reduced height mobile phone telephoto lens of the present application, the incident surface, the total reflection surface and the exit surface are common planes. And in one exemplary embodiment, according to the reduced height mobile phone telephoto lens of the present application, the prism G5 is a trapezoidal prism, the incident surface, the total reflection surface and the exit surface can be jointly arranged on the longer bottom edge of the trapezoidal prism, and the first reflection surface and the second reflection surface can be respectively arranged on the two waists of the trapezoidal prism.

[0031] In an exemplary embodiment, according to the reduced height mobile phone telephoto lens of the present application, one or more of the first reflection surface, the total reflection surface and the second reflection surface are coated with a reflective film, which can ensure that the light can be completely reflected and reduce the risk of light being refracted out of the prism G5.

[0032] In an exemplary embodiment, the reduced height mobile phone telephoto lens according to the present application can satisfy CT1+CT2+CT3+CT4+T1+T2+T3<3.3mm; wherein the center thickness of the first lens G1 is CT1, the center thickness of the second lens G2 is CT2, the center thickness of the third lens G3 is CT3, the center thickness of the fourth lens G4 is CT4, the space gap between the first lens G1 and the second lens G2 is T1, the space gap between the second lens G2 and the third lens G3 is T2, and the space gap between the third lens G3 and the fourth lens G4 is T3. Satisfying CT1+CT2+CT3+CT4+T1+T2+T3<3.3mm, by controlling the center thicknesses CT1-CT4 of the first lens G1 to the fourth lens G4 and the air gap T1-T3 between the lenses, it is beneficial to realize the miniaturization of the mobile phone telephoto lens.

[0033] In an exemplary embodiment, the reduced height mobile phone telephoto lens according to the present application can satisfy 0.33mm<T4<0.55mm; wherein the air gap between the fourth lens G4 and the prism G5 is T4. Satisfying 0.33mm<T4<0.55mm and controlling the air gap T4 between the fourth lens G4 and the prism G5 is conducive to miniaturization of the mobile phone telephoto lens.

[0034] In an exemplary embodiment, the reduced height mobile phone telephoto lens according to the present application can satisfy 0.7<f / BFL<1; wherein, the effective focal length of the reduced height mobile phone telephoto lens is f, and the distance from the image side of the fourth lens G4 to the image plane IMG is BFL. Satisfying 0.7<f / BFL<1, by controlling the effective focal length f of the reduced height mobile phone telephoto lens, the distance BFL from the image side of the fourth lens G4 to the image plane IMG, if the value of f / BFL is less than the lower limit, astigmatism, distortion, etc. may occur; if the value of f / BFL is greater than the upper limit, the lens resolution may be insufficient, affecting the imaging quality; and the appropriate value of f / BFL can be used to achieve excellent imaging quality at object distances from 25cm to infinity.

[0035] In an exemplary embodiment, the reduced height mobile phone telephoto lens according to the present application may satisfy 1<((f / f4)+(f / f2))<4; wherein, the effective focal length of the reduced height mobile phone telephoto lens is f, the effective focal length of the second lens G2 is f2, and the effective focal length of the fourth lens G4 is f4. Satisfying 1<((f / f4)+(f / f2))<4, by controlling the effective focal length f of the reduced height mobile phone telephoto lens, the effective focal length f2 of the second lens G2, and the effective focal length f4 of the fourth lens G4, a suitable focal length and depth of field may be obtained, and astigmatism, distortion, chromatic aberration, etc. may be avoided, and it may be used to achieve excellent imaging quality at object distances from 25 cm to infinity.

[0036] In an exemplary embodiment, the reduced height mobile phone telephoto lens according to the present application may satisfy 0<((f / f4)-(f / f2))<3; wherein, the effective focal length of the reduced height mobile phone telephoto lens is f, the effective focal length of the second lens G2 is f2, and the effective focal length of the fourth lens G4 is f4. Satisfying 0<((f / f4)-(f / f2))<3, by controlling the effective focal length f of the reduced height mobile phone telephoto lens, the effective focal length f2 of the second lens G2, and the effective focal length f4 of the fourth lens G4, a suitable focal length and depth of field can be obtained, and astigmatism, distortion, chromatic aberration, etc. can be avoided, which can be used to achieve excellent imaging quality at object distances from 25 cm to infinity.

[0037] In an exemplary embodiment, reference may be made to Figure 1According to the reduced height of the mobile phone telephoto lens of the present application, 11mm<CT5<14mm can be satisfied; wherein, the thickness CT5 of the prism G5 satisfies 11mm<CT5<14mm. By controlling the thickness CT5 of the prism G5, the optical path of the light inside the prism G5 can be adjusted, so that the light can be correctly focused on the image plane IMG, thereby improving the image quality.

[0038] In an exemplary embodiment, the reduced height of the mobile phone telephoto lens according to the present application can meet 1.55≤n1≤1.98, and 45≤V1≤90; wherein, the refractive index of the first lens G1 is n1, and the dispersion coefficient of the first lens G1 is V1. When 1.55≤n1≤1.98, and 45≤V1≤90 are satisfied, the chromatic aberration of the first lens G1 can be controlled by the refractive index n1 of the first lens G1 and the dispersion coefficient V1 of the first lens G1, the burden of correcting chromatic aberration of other lenses is reduced, and freedom is reserved for correcting other aberrations.

[0039] In an exemplary embodiment, the reduced height mobile phone telephoto lens according to the present application can satisfy 19<(DT11+DT21) / (DT12 / DT22)<21; wherein, the maximum effective diameter of the object side of the first lens G1 is DT11, the maximum effective diameter of the image side of the first lens G1 is DT12, the maximum effective diameter of the object side of the second lens G2 is DT21, and the maximum effective diameter of the image side of the second lens G2 is DT22. Satisfying 19<(DT11+DT21) / (DT12 / DT22)<21, by controlling the maximum effective diameter DT11 of the object side of the first lens G1, the maximum effective diameter DT12 of the image side of the first lens G1, the maximum effective diameter DT21 of the object side of the second lens G2, and the maximum effective diameter DT22 of the image side of the second lens G2, a balance between increasing the amount of light entering and reducing aberrations can be achieved, thereby improving the imaging quality.

[0040] In an exemplary embodiment, reference may be made to Figure 2 According to the reduced height of the mobile phone telephoto lens of the present application, 0.2<CT6 / L1<0.3 can be satisfied; wherein, the thickness of the prism G5 after the folded light path is CT6, and the total length is L1. Satisfying 0.2<CT6 / L1<0.3, by controlling the thickness CT6 and the total length L1 of the prism G5 after the folded light path, the light can be controlled to reflect at a specific angle inside the prism G5, thereby controlling the thickness CT6 of the prism G5 after the folded light path, which is conducive to miniaturization of the mobile phone telephoto lens.

[0041] In an exemplary embodiment, the reduced height mobile phone telephoto lens according to the present application can satisfy 31°<A<35°, wherein the angle after the prism G5 folds the light path is A. Satisfying 31°<A<35°, by controlling the angle A after the prism G5 folds the light path, and then controlling the thickness CT6 of the prism G5 after the folded light path, it is beneficial to realize the miniaturization of the mobile phone telephoto lens.

[0042] In an exemplary embodiment, the reduced height mobile phone telephoto lens according to the present application further includes an aperture STO, which is disposed between the first lens G1 and the second lens G2 to further improve the overall performance. In other exemplary embodiments, the aperture STO may be disposed between other lenses.

[0043] In an exemplary embodiment, the reduced height mobile phone telephoto lens according to the present application further includes a filter IR for correcting color deviation and / or a protective glass for protecting the photosensitive element located on the image plane IMG.

[0044] 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.

[0045] A specific embodiment of the mobile phone telephoto lens with a reduced height applicable to the above-mentioned embodiment will be further described below with reference to the accompanying drawings.

[0046] Example 1 The following reference Figure 3 Describe the reduced height telephoto lens for a mobile phone according to Example 1 of the present application. Figure 3 A lens equivalent structure diagram of a mobile phone telephoto lens with a reduced height according to Example 1 of the present application is shown.

[0047] like Figure 3 As shown, the reduced height mobile phone telephoto lens includes, from the object side to the image side, a first lens G1, an aperture STO, a second lens G2, a third lens G3, a fourth lens G4, a prism G5, a filter IR and an image plane IMG. The first lens G1 to the fourth lens G4 each include an object side facing the object side and allowing imaging light to pass through, and an image side facing the image side and allowing imaging light to pass through.

[0048] The first lens G1 has positive focal power, and its object side 11 is convex, and its image side 12 is convex. The second lens G2 has positive focal power, and its object side 21 is concave, and its image side 22 is convex. The third lens G3 has positive focal power, and its object side 31 is concave, and its image side 32 is concave. The fourth lens G4 has negative focal power, and its object side 41 is convex, and its image side 42 is convex. The prism G5 is a trapezoidal prism, and has an object side 51 and an image side 52. The filter IR has an object side 61 and an image side 62. Light from an object passes through the first lens G1, the aperture STO, the second lens G2, the third lens G3, the fourth lens G4, the prism G5, and the filter IR in sequence, and is finally imaged on the image plane IMG.

[0049] Table 1 shows the basic parameters of the reduced height mobile phone telephoto lens of Example 1, wherein the units of the curvature radius, thickness, focal length and aperture are all millimeters (mm).

[0050] Table 1:

[0051] In Example 1, the object side and the image side of the first lens G1 are both standard surfaces, and the object side and the image side of any one of the second lens G2 to the fourth lens G4 are both extended aspheric surfaces. The surface shape of each extended aspheric surface can be defined by, but not limited to, the following aspheric surface formula: (1) Wherein, x is the distance vector height from the vertex of the extended aspheric surface when the extended aspheric surface is at a height of h along the optical axis; c is the paraxial curvature of the extended aspheric surface, c=1 / R (i.e., the paraxial curvature c is the inverse of the radius of curvature in Table 1 above); k is the cone coefficient; Ai is the correction coefficient of the i-th order of the extended aspheric surface. Table 2 below shows the high-order coefficients A4, A6, A8, A10, A12, A14 and A16 that can be used for each extended aspheric mirror surface 21-42 in Example 1.

[0052] Table 2:

[0053] In this embodiment, the focal length of the mobile phone telephoto lens with a reduced height is 11.2mm, the working band of the mobile phone telephoto lens with a reduced height is 430-650nm, the aperture of the mobile phone telephoto lens with a reduced height is 2.65, the imaging circle diameter of the mobile phone telephoto lens with a reduced height is 7mm, the field of view angle is 32.6°, and the total optical length of the mobile phone telephoto lens with a reduced height is 17.04mm. The relationship between the center thickness CT1-CT4 of the first lens G1 to the fourth lens G4 and the air gap T1-T3 between the lenses is CT1+CT2+CT3+CT4+T1+T2+T3=3.09mm. The relationship between the air gap T4 between the fourth lens G4 and the prism G5 is: T4=0.5mm. The effective focal length f of the mobile phone telephoto lens and the distance BFL from the image side to the image plane of the fourth lens are f / BFL=0.8.

[0054] Figure 4 The MTF curve of the reduced height mobile phone telephoto lens of Example 1 is shown. The MTF (Modulation Transfer Function) curve is the degree to which the lens reproduces the details of the subject on the image plane IMG as the spatial frequency changes. The MTF meets the design requirements and the lens imaging quality is very good. Figure 5 The relative illumination and Y field of view of the telephoto lens of the mobile phone with a reduced height of Example 1 are shown. The relative illumination is greater than 72%, and the brightness of the picture is uniform. Figure 6 The distortion diagram of the telephoto lens of the mobile phone with a reduced height of Example 1 is shown, and the absolute value of the distortion is less than 0.2%, which is very well corrected. Figure 7 The light fan diagram of the mobile phone telephoto lens with reduced height of Example 1 is shown, with a scale of ±10μm and imaging magnification error values ​​all within an acceptable range. Figure 8 The vertical axis chromatic aberration diagram of the mobile phone telephoto lens with reduced height of Example 1 is shown, which shows that when the maximum field of view is 16.8000 degrees, the focus deviation of light of different wavelengths formed on the imaging plane along the direction perpendicular to the optical axis is within 2.4 μm, and the color reproduction is good. Figures 4 to 8 It can be seen that the reduced height mobile phone telephoto lens provided in Example 1 can achieve good imaging quality.

[0055] Example 2 The following reference Fig. 9 Describe the reduced height telephoto lens for a mobile phone according to Example 2 of the present application. Fig. 9 The lens equivalent structure diagram of the mobile phone telephoto lens with reduced height according to Embodiment 2 of the present application is shown. In this embodiment, for the sake of brevity, some descriptions similar to Embodiment 1 will be omitted.

[0056] like Fig. 9As shown, the reduced height mobile phone telephoto lens includes, from the object side to the image side, a first lens G1, an aperture STO, a second lens G2, a third lens G3, a fourth lens G4, a prism G5, a filter IR and an image plane IMG. The first lens G1 to the fourth lens G4 each include an object side facing the object side and allowing imaging light to pass through, and an image side facing the image side and allowing imaging light to pass through.

[0057] The first lens G1 has positive focal power, and its object side 11 is convex, and its image side 12 is convex. The second lens G2 has positive focal power, and its object side 21 is convex, and its image side 22 is concave. The third lens G3 has positive focal power, and its object side 31 is concave, and its image side 32 is concave. The fourth lens G4 has negative focal power, and its object side 41 is convex, and its image side 42 is convex. The prism G5 is a trapezoidal prism, and has an object side 51 and an image side 52. The filter IR has an object side 61 and an image side 62. Light from an object passes through the first lens G1, the aperture STO, the second lens G2, the third lens G3, the fourth lens G4, the prism G5, and the filter IR in sequence, and is finally imaged on the image plane IMG.

[0058] Table 3 shows the basic parameter table of the reduced height mobile phone telephoto lens of Example 2, wherein the units of the curvature radius, thickness, focal length and aperture are all millimeters (mm).

[0059] Table 3:

[0060] Table 4 shows the high-order coefficients that can be used for each extended aspheric mirror surface 21-42 in Example 2, wherein the surface shape of each extended aspheric mirror surface 21-42 can be defined by the formula (1) given in the above-mentioned Example 1.

[0061] Table 4:

[0062] In this embodiment, the focal length of the mobile phone telephoto lens with a reduced height is 11.6mm, the working band of the mobile phone telephoto lens with a reduced height is 430-650nm, the aperture of the mobile phone telephoto lens with a reduced height is 2.65, the imaging circle diameter of the mobile phone telephoto lens with a reduced height is 7mm, the field of view angle is 31.6°, and the total optical length of the mobile phone telephoto lens with a reduced height is 17.04mm. The relationship between the center thickness CT1-CT4 of the first lens G1 to the fourth lens G4 and the air gap T1-T3 between the lenses is CT1+CT2+CT3+CT4+T1+T2+T3=3.10mm. The relationship between the air gap T4 between the fourth lens G4 and the prism G5 is: T4=0.5mm. The effective focal length f of the mobile phone telephoto lens and the distance BFL from the image side to the image plane of the fourth lens are f / BFL=0.8.

[0063] Fig.10 The MTF curve of the reduced height mobile phone telephoto lens of Example 2 is shown. The MTF (Modulation Transfer Function) curve is the degree to which the lens reproduces the details of the subject on the image plane IMG as the spatial frequency changes. The MTF meets the design requirements and the lens imaging quality is very good. Fig.11 The relative illumination and Y field of view of the telephoto lens of the mobile phone with a reduced height of Example 2 are shown. The relative illumination is greater than 70%, and the brightness of the picture is uniform. Fig.12 The distortion diagram of the telephoto lens of the mobile phone with a reduced height of Example 2 is shown, and the absolute value of the distortion is less than 1%, and the correction is very good. Fig.13 The light fan diagram of the mobile phone telephoto lens with reduced height of Example 2 is shown, with a scale of ±40μm, and the imaging magnification error values ​​are all within an acceptable range. Fig.14 The vertical axis chromatic aberration diagram of the mobile phone telephoto lens with reduced height of Example 2 is shown, which shows that when the maximum field of view is 3.6000 mm, the focus deviation of light of different wavelengths formed on the imaging plane along the direction perpendicular to the optical axis is within 4μm, and the color reproduction is good. Figures 10 to 14 It can be seen that the reduced height mobile phone telephoto lens provided in Example 2 can achieve good imaging quality.

[0064] 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 mobile phone telephoto lens with a reduced height, characterized in that: The sequence from the object side to the image side includes: a first lens, a second lens, a third lens, a fourth lens, a prism and an image plane; wherein, The first lens has positive optical power; the second lens has positive optical power; the third lens has positive optical power; the fourth lens has negative optical power; The prism has an incident surface, a first reflection surface, a total reflection surface, a second reflection surface and an exit surface. The light emitted by the fourth lens enters the prism from the incident surface, is reflected at least once by the first reflection surface, the total reflection surface and the second reflection surface, and then is emitted to the image surface through the exit surface.

2. The height-reduced mobile phone telephoto lens according to claim 1, characterized in that: The light emitted from the fourth lens is incident into the prism through the incident surface along the first optical axis direction, is reflected by the first reflection surface to reach the total reflection surface along the second optical axis direction, is then reflected by the total reflection surface to reach the second reflection surface along the third optical axis direction, is then reflected by the second reflection surface to reach the exit surface along the fourth optical axis direction, and is then emitted to the image plane through the exit surface.

3. The height-reduced mobile phone telephoto lens according to claim 1, characterized in that: The center thickness CT1 of the first lens, the center thickness CT2 of the second lens, the center thickness CT3 of the third lens, the center thickness CT4 of the fourth lens, the space gap T1 between the first lens and the second lens, the space gap T2 between the second lens and the third lens, and the space gap T3 between the third lens and the fourth lens satisfy: CT1+CT2+CT3+CT4+T1+T2+T3<3.3mm.

4. The height-reduced mobile phone telephoto lens according to claim 1, characterized in that: An air gap T4 between the fourth lens and the prism satisfies: 0.33 mm<T4<0.55 mm.

5. The height-reduced mobile phone telephoto lens according to claim 1, characterized in that: The effective focal length f of the mobile phone telephoto lens and the distance BFL from the image side of the fourth lens to the image plane satisfy: 0.7<f / BFL<1.

6. The height-reduced mobile phone telephoto lens according to claim 1, characterized in that: The effective focal length f of the mobile phone telephoto lens, the effective focal length f2 of the second lens, and the effective focal length f4 of the fourth lens satisfy: 1<((f / f4)+(f / f2))<4.

7. The height-reduced mobile phone telephoto lens according to claim 1, characterized in that: The effective focal length f of the mobile phone telephoto lens, the effective focal length f2 of the second lens, and the effective focal length f4 of the fourth lens satisfy: 0<((f / f4)-(f / f2))<3.

8. The height-reduced mobile phone telephoto lens according to claim 1, characterized in that: The thickness CT5 of the prism satisfies: 11 mm<CT5<14 mm.

9. The height-reduced mobile phone telephoto lens according to claim 1, characterized in that: The object side maximum effective diameter DT11 of the first lens, the image side maximum effective diameter DT12 of the first lens, the object side maximum effective diameter DT21 of the second lens, and the image side maximum effective diameter DT22 of the second lens satisfy: 19<(DT11+DT21) / (DT12 / DT22)<21.

10. The height-reduced mobile phone telephoto lens according to claim 1, characterized in that: The thickness CT6 of the prism after folding the light path and the total length L1 of the prism after light conversion satisfy: 0.2<CT6 / L1<0.3.

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