Telephoto lens and electronic equipment
By combining prism reflection and lens design, the problem of the large height of telephoto lenses was solved, achieving lens miniaturization and high-quality imaging, thus improving the user experience.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- KUNSHAN Q TECH CO LTD
- Filing Date
- 2025-04-30
- Publication Date
- 2026-05-19
AI Technical Summary
Telephoto lenses, due to their longer back focal length and greater lens height, affect the appearance and aesthetics of electronic devices.
By employing a prism design, light is reflected twice internally, and by rationally allocating the optical power, spacing, and refractive index of the lenses, the effect of a large target surface, a large aperture, and a short overall optical length is achieved, thereby reducing the lens height.
It effectively reduces lens height, improves image quality, and enhances the appearance and user experience of electronic devices.
Smart Images
Figure CN224263468U_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of optical imaging technology, and in particular to a telephoto lens and an electronic device. Background Technology
[0002] As various electronic products become increasingly multifunctional, camera functionality has become a standard feature in smartphones, tablets, and other electronic products.
[0003] However, as users' demands for image quality continue to increase, telephoto lenses, due to their longer back focal length, generally have the problem of being too tall and protruding from the camera body, which affects the overall appearance and aesthetics of the camera. Utility Model Content
[0004] In view of the above problems, the purpose of this utility model is to provide a telephoto lens that effectively reduces the overall height and is conducive to the miniaturization of the lens.
[0005] This invention provides a telephoto lens, comprising, from the object side to the image side, a lens assembly, a prism, and an image sensor. The lens assembly includes a plurality of lenses arranged in sequence. The prism includes an incident surface facing the lens assembly, a first reflecting surface, a second reflecting surface, and an exiting surface facing the image sensor. The first reflecting surface is used to reflect light from the incident surface for the first time and reflect it to the second reflecting surface. The second reflecting surface is used to reflect light from the first reflecting surface for the second time and reflect it to the exiting surface. The incident surface is perpendicular to the second reflecting surface. The first reflecting surface and the exiting surface are on the same plane. The exiting surface is inclined relative to the second reflecting surface and closer to the incident surface. The imaging surface of the image sensor is disposed relative to the exiting surface.
[0006] Optionally, the first reflective surface and / or the second reflective surface are provided with a reflective film.
[0007] Optionally, the plurality of lenses includes a first lens, a second lens, a third lens, and a fourth lens, with the incident surface facing the fourth lens. The effective aperture D10 of the image-side surface of the fourth lens and the effective aperture D11 of the incident surface satisfy: 0.8 <D10 / D11<1.2。
[0008] Optionally, the effective aperture D11 of the incident surface and the effective aperture D12 of the exit surface satisfy: 0.2 <D11 / D12<0.5。
[0009] Optionally, the included angle θ1 between the first reflecting surface and the second reflecting surface satisfies: 25° < θ1 < 35°, and the included angle θ2 between the incident surface and the first reflecting surface satisfies: 50° < θ2 < 70°.
[0010] Optionally, the angle θ3 between the exit surface and the zero field-of-view principal ray is 90°.
[0011] Optionally, the plurality of lenses includes a first lens, a second lens, a third lens, and a fourth lens, with the incident surface facing the fourth lens, and the focal length f1 of the first lens and the focal length f of the telephoto lens satisfying: 0.3 <f1 / f<0.6。
[0012] Optionally, the plurality of lenses includes a first lens, a second lens, a third lens, and a fourth lens, with the incident surface facing the fourth lens. The focal length f4 of the fourth lens and the focal length f of the telephoto lens satisfy: -0.9 <f4 / f<-0.5。
[0013] Optionally, the telephoto lens further includes an aperture stop, the plurality of lenses include a first lens, a second lens, a third lens and a fourth lens, the incident surface is disposed toward the fourth lens, and the aperture stop is disposed on the object side of the first lens.
[0014] Optionally, the telephoto lens further includes a filter for correcting color deviation and / or a protective glass for protecting the photosensitive element located on the imaging surface, the filter being disposed between the exit surface and the imaging surface.
[0015] This invention also provides an electronic device, including the aforementioned telephoto lens.
[0016] The telephoto lens provided by this utility model reflects light twice internally through the first and second reflecting surfaces of a prism before exiting onto the imaging surface. The back focal length of the lens is folded twice inside the prism, which reduces the overall height and improves image quality. At the same time, the imaging surface is tilted to follow the exit surface, which can further reduce the overall height. On the other hand, by reasonably allocating the optical power, spacing and refractive index of each lens in the lens assembly, the effect of large target area, large aperture and short optical length can be achieved, which is conducive to lens miniaturization and improves the user experience. Attached Figure Description
[0017] 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.
[0018] Figure 1 A schematic diagram of the structure of a telephoto lens according to an embodiment of this application is shown.
[0019] Figure 2A schematic diagram of the telephoto lens of Embodiment 1 of this application is shown.
[0020] Figures 3 to 5 The MTF curve, aperture fan diagram, relative illumination and Y field of view diagram of the telephoto lens of Example 1 are shown respectively.
[0021] Figure 6 A schematic diagram of the telephoto lens of Embodiment 2 of this application is shown.
[0022] Figures 7 to 9 The MTF curve, fan diagram, relative illumination and Y field of view diagram of the telephoto lens of Example 2 are shown respectively.
[0023] Figure 10 A schematic diagram of the telephoto lens of Embodiment 3 of this application is shown.
[0024] Figures 11 to 13 The MTF curve, fan diagram, relative illumination and Y field of view diagram of the telephoto lens of Example 3 are shown respectively. Detailed Implementation
[0025] 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.
[0026] It is important to understand that the terms "first," "second," "third," "fourth," etc., are used merely to distinguish elements or circuits with similar properties, and do not indicate or imply relative importance or a specific order. The terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, which includes not only the listed elements but also other elements not expressly listed.
[0027] In the accompanying drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for ease of illustration. Specifically, the shapes of the spherical or aspherical surfaces shown in the drawings are illustrated by way of example only. That is, the shapes of the spherical or aspherical surfaces are not limited to those shown in the drawings. The drawings are for illustrative purposes only and are not drawn strictly to scale.
[0028] In this article, the paraxial region refers to the region near the optical axis. If the lens surface is convex and the location of the convexity is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the location of the concaveness is not defined, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the subject is called the object-side surface of the lens, and the surface of each lens closest to the imaging plane (IMG) is called the image-side surface of the lens.
[0029] 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.
[0030] The features, principles and other aspects of this application are described in detail below.
[0031] Figure 1 A schematic diagram of the structure of a telephoto lens according to an embodiment of this application is shown. Figure 1 As shown, a telephoto lens, from the object side to the image side, includes: a lens assembly 10, a prism P, and an image sensor. The lens assembly 10 includes a plurality of lenses arranged in sequence. The prism P includes an incident surface P1 facing the lens assembly 10, a first reflecting surface P2, a second reflecting surface P3, and an exiting surface P4 facing the image sensor. The first reflecting surface P2 is used to reflect light from the incident surface P1 for the first time and reflect it to the second reflecting surface P3. The second reflecting surface P3 is used to reflect light from the first reflecting surface P2 for the second time and reflect it to the exiting surface P4. The incident surface P1 is perpendicular to the second reflecting surface P3. The first reflecting surface P2 and the exiting surface P4 are on the same plane. The exiting surface P4 is inclined relative to the second reflecting surface P3 and closer to the incident surface P1. The imaging surface IMG of the image sensor is set relative to the exiting surface P4.
[0032] When the telephoto lens of this application is in use, light passes sequentially through the lens assembly 10 and the incident surface P1 into the prism P, undergoes a first reflection through the first reflecting surface P2 and is reflected to the second reflecting surface P3, then undergoes a second reflection through the second reflecting surface P3 and is reflected to the exit surface P4, and is emitted from the exit surface P4 to the imaging surface IMG.
[0033] The lens assembly 10 may include multiple lenses, for example, 4 lenses, or other numbers of lenses. Each lens has a corresponding optical power for telephoto imaging. The light is reflected twice inside by the first reflecting surface P2 and the second reflecting surface P3 of the prism P and then emitted to the imaging surface IMG. The back focal length of the lens is folded twice inside the prism P, and the structure can be more compact, the overall height can be reduced, and the imaging quality can be improved. At the same time, the incident surface P1 is perpendicular to the second reflecting surface P3, and the imaging surface IMG is arranged obliquely following the exit surface P4, and the image sensor is also arranged obliquely correspondingly, which is beneficial to correcting the propagation path of the light and can further reduce the overall height. On the other hand, by reasonably distributing the optical power, spacing, refractive index, etc. of each lens in the lens assembly, the effects of large target surface, large aperture, and short overall optical length can be achieved, which is beneficial to the miniaturization of the lens, the appearance of the electronic device can be improved accordingly, and the user experience can be enhanced.
[0034] In an exemplary embodiment, a reflective film is provided on the first reflecting surface P2 and / or the second reflecting surface P3. Thus, when the light is reflected for the first time on the first reflecting surface P2 and / or for the second time on the second reflecting surface P3, it can be ensured that the light can be completely reflected, reducing the risk that the light is refracted out of the prism when passing through the first reflecting surface P2 and / or the second reflecting surface P3, which is beneficial to improving the imaging quality.
[0035] In an exemplary embodiment, the multiple lenses include a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4. The incident surface P1 faces the fourth lens L4. The effective aperture D10 of the image side of the fourth lens L4 and the effective aperture D11 of the incident surface P1 satisfy: 0.8 < D10 / D11 < 1.2. By controlling the ratio of the effective aperture D10 of the image side of the fourth lens L4 to the effective aperture D11 of the incident surface P1 within a reasonable range, the width of the prism P can be effectively controlled, meeting the small-size requirement, which is beneficial to the miniaturization of the lens and the large-aperture design.
[0036] In an exemplary embodiment, the effective aperture D11 of the incident surface P1 and the effective aperture D12 of the exit surface P4 satisfy: 0.2 < D11 / D12 < 0.5. By controlling the ratio of the effective aperture D11 of the incident surface P1 to the effective aperture D12 of the exit surface P4 within a reasonable range, the length of the prism P can be effectively controlled, meeting the small-size requirement, which is beneficial to the miniaturization of the lens and the large-aperture design.
[0037] In an exemplary embodiment, the included angle θ1 between the first reflecting surface P2 and the second reflecting surface P3 satisfies: 25° < θ1 < 35°, and the included angle θ2 between the incident surface P1 and the first reflecting surface P2 satisfies: 50° < θ2 < 70°. By controlling the included angle θ1 between the first reflecting surface P2 and the second reflecting surface P3 and the included angle θ2 between the incident surface P1 and the first reflecting surface P2, the thickness of the prism P can be effectively reduced to meet the small-size requirement. At the same time, the imaging surface IMG is inclined along with the exit surface P4, and the image sensor is also inclined correspondingly, which can further reduce the overall height.
[0038] In an exemplary embodiment, the included angle θ3 between the exit surface P4 and the chief ray of the zero field of view is 90°, which can ensure that the exit angle of the chief ray of the zero field of view is 0°. It can reduce the astigmatism and other optical aberrations caused by refraction, and can also reduce the generation of reflections, further reducing the optical aberrations. Thus, the generation of chromatic aberration can be reduced, avoiding vignetting or color cast in the picture, which helps to improve the imaging quality and accuracy of the optical system.
[0039] In an exemplary embodiment, the multiple lenses include a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4. The incident surface P1 is arranged facing the fourth lens L4. The focal length f1 of the first lens L1 and the focal length f of the telephoto lens satisfy: 0.3 < f1 / f < 0.6. By controlling the ratio of the focal length f1 of the first lens L1 to the focal length f of the telephoto lens within a suitable range, it is beneficial to converge light, reduce the deflection angle of the light rays of the subsequent lenses, and improve the imaging quality.
[0040] In an exemplary embodiment, the multiple lenses include a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4. The incident surface P1 is arranged facing the fourth lens L4. The focal length f4 of the fourth lens L4 and the focal length f of the telephoto lens satisfy: -0.9 < f4 / f < -0.5. By controlling the ratio of the focal length f4 of the fourth lens L4 to the focal length f of the telephoto lens within a reasonable range, it is beneficial to correct spherical aberration and improve the resolution.
[0041] In an exemplary embodiment, the telephoto lens further includes an aperture STO. The multiple lenses include a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4. The incident surface P1 is arranged facing the fourth lens L4. The aperture STO is arranged on the object side surface of the first lens L1, which is beneficial to adjust the intensity of the light beam entering the first lens L1 and improve the imaging effect.
[0042] In an exemplary embodiment, the telephoto lens further includes a filter IR for correcting color deviation and / or a protective glass for protecting the photosensitive element located on the imaging surface IMG. The filter IR is arranged between the exit surface P4 and the imaging surface IMG, which is beneficial to correct the aberrations generated by the imaging system.
[0043] Based on the same inventive concept, this application also provides an electronic device, including the aforementioned telephoto lens. The electronic device includes, but is not limited to, smartphones, tablets, laptops, gimbal cameras, surveillance cameras, and other imaging devices. Implementations of this electronic device can be found in the embodiments of the telephoto lens; repeated details will not be elaborated further.
[0044] However, those skilled in the art will understand that the number of lenses constituting the lens assembly 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 have been described as an example in the embodiments, the lens assembly is not limited to including four lenses. If desired, the lens assembly may also include other numbers of lenses.
[0045] The following describes in further detail, with reference to the accompanying drawings, specific embodiments of the telephoto lens applicable to the above-described embodiments.
[0046] Example 1
[0047] The following is for reference Figure 2 A telephoto lens according to Embodiment 1 of this application is described.
[0048] The telephoto lens of Embodiment 1, from the object side to the image side, includes: a lens assembly 10, a prism P, and an image sensor. The lens assembly 10 includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4 arranged in sequence. The prism P includes an incident surface P1 facing the fourth lens L4, a first reflecting surface P2, a second reflecting surface P3, and an exit surface P4 facing the image sensor. The first reflecting surface P2 is used to reflect light from the incident surface P1 for the first time and reflect it to the second reflecting surface P3. The second reflecting surface P3 is used to reflect light from the first reflecting surface P2 for the second time and reflect it to the exit surface P4. The incident surface P1... 1. Perpendicular to the second reflecting surface P3, the first reflecting surface P2 and the exiting surface P4 are on the same plane. The exiting surface P4 is inclined relative to the second reflecting surface P3 and closer to the incident surface P1. The imaging surface IMG of the image sensor is set relative to the exiting surface P4. The first reflecting surface P2 is provided with a reflective film. The angle θ1 between the first reflecting surface P2 and the second reflecting surface P3 is 30°. The angle θ2 between the incident surface P1 and the first reflecting surface P2 is 60°. The angle θ3 between the exiting surface P4 and the zero field principal ray is 90°. The aperture STO is set on the object side of the first lens L1. The filter IR is set between the exiting surface P4 and the imaging surface IMG.
[0049] The first lens L1 has positive optical power, with a convex object-side surface and a concave image-side surface. The second lens L2 has negative optical power, with a convex object-side surface and a concave image-side surface. The third lens L3 has positive optical power, with a convex object-side surface and a concave image-side surface. The fourth lens L4 has negative optical power, with a concave object-side surface and a convex image-side surface. The filter IR has an object-side surface and an image-side surface. Light rays pass sequentially through the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the incident surface P1 into the prism P. They are reflected by the first reflecting surface P2 to the second reflecting surface P3 (the first reflection), then reflected again by the second reflecting surface P3 to the exit surface P4 (the second reflection), and finally imaged onto the imaging surface IMG.
[0050] Table 1 shows the basic parameters of the telephoto lens of Example 1, where the units for radius of curvature, thickness, focal length, and effective aperture are all millimeters (mm).
[0051] Table 1:
[0052]
[0053] Wherein, L1-R1 represents the object-side surface of the first lens L1, L1-R2 represents the image-side surface of the first lens L1, 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, P-R1 represents the object-side surface of the prism P (i.e., the incident surface P1), P-R2 represents the image-side surface of the prism P (i.e., the exit surface P4), IR-R1 represents the object-side surface of the filter IR, and IR-R2 represents the image-side surface of the filter IR.
[0054] In Embodiment 1, the object-side surface and image-side surface of any one of the first lens L1 to the fourth lens L4 are both even-order aspherical surfaces. The surface shape of each aspherical lens can be defined using, but is not limited to, the following aspherical formula:
[0055] (1)
[0056] Where Z represents the height along the optical axis, c is the reciprocal of the surface radius, k is the conic coefficient, and r is the aperture along the radial direction; α represents the aspherical coefficient, α1 represents the aspherical coefficient A2, α2 represents the aspherical coefficient A4, and so on. Table 2 gives the higher-order coefficients A2, A4, A6, A8, A10, A12, A14, and A16 that can be used for each aspherical mirror in Example 1.
[0057] Table 2:
[0058]
[0059] In Example 1, light is reflected twice internally by the first reflecting surface P2 and the second reflecting surface P3 of the prism P before exiting to the imaging surface IMG. The back focal length of the lens is folded twice inside the prism P, making the structure more compact, reducing the overall height and improving the image quality. At the same time, the incident surface P1 is perpendicular to the second reflecting surface P3, and the imaging surface IMG is tilted to follow the exit surface P4. The image sensor is also tilted accordingly, which helps to correct the propagation path of light and further reduces the overall height. On the other hand, by reasonably allocating the optical power, spacing and refractive index of the first lens L1 to the fourth lens L4 in the table above, the effect of a large target surface, a large aperture and a short optical length can be achieved, which is conducive to lens miniaturization, improves the appearance of electronic devices, and enhances the user experience. The telephoto lens has a focal length of f = 14.3mm, an aperture of f = 2.5, an image circle diameter of 9.4mm, a field of view of 33°, and an operating wavelength of 420~680nm. The effective aperture of the image side of the fourth lens L4 is D10 = 4.70mm, the effective aperture of the incident surface P1 is D11 = 4.89mm, the effective aperture of the exit surface P4 is D12 = 14.03mm, the focal length of the first lens L1 is f1 = 7.17mm, and the focal length of the fourth lens L4 is f4 = -12.3mm. The effective aperture D10 of the image-side surface of the fourth lens L4 is related to the effective aperture D11 of the incident surface P1 by D10 / D11 = 0.96; the effective aperture D11 of the incident surface P1 is related to the effective aperture D12 of the exit surface P4 by D11 / D12 = 0.35; the focal length f1 of the first lens L1 is related to the focal length f of the telephoto lens by f1 / f = 0.50; the focal length f4 of the fourth lens L4 is related to the focal length f of the telephoto lens by f4 / f = -0.86.
[0060] Figure 3 The MTF curve of the telephoto lens in Example 1 is shown. The MTF (Modulation Transfer Function) curve shows the transmission of image details (i.e. image contrast) at different spatial frequencies by the imaging system. At a spatial frequency of 90 lp / mm, the MTF value is greater than 0.5, indicating good resolution and good imaging effect. Figure 4 The optical fan diagram of the telephoto lens of Example 1 is shown. The optical fan diagram typically shows the cross-section of the light beam at different positions, as well as the path and variation of its propagation in the optical system. It is a comprehensive evaluation diagram of various aberrations, with a scale of ±20µm, that is, the scale range in the horizontal and vertical directions is ±20µm, and various aberrations are well corrected. Figure 5 The diagram shows the relative illuminance and Y-field angle of the telephoto lens in Example 1. The relative illuminance is greater than 0.6, and the illuminance is uniform. According to... Figures 3 to 5 As can be seen, the telephoto lens given in Example 1 has well-corrected aberrations, uniform illumination, and good resolution, and can achieve good image quality.
[0061] Example 2
[0062] The following is for reference Figure 6 This application describes a telephoto lens according to Embodiment 2. For the sake of brevity, descriptions similar to those in Embodiment 1 are omitted in this embodiment.
[0063] The telephoto lens of Embodiment 2, from the object side to the image side, includes: a lens assembly 10, a prism P, and an image sensor. The lens assembly 10 includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4 arranged in sequence. The prism P includes an incident surface P1 facing the fourth lens L4, a first reflecting surface P2, a second reflecting surface P3, and an exit surface P4 facing the image sensor. The first reflecting surface P2 is used to reflect light from the incident surface P1 for the first time and reflect it to the second reflecting surface P3. The second reflecting surface P3 is used to reflect light from the first reflecting surface P2 for the second time and reflect it to the exit surface P4. The incident surface P1... 1. Perpendicular to the second reflecting surface P3, the first reflecting surface P2 and the exiting surface P4 are on the same plane. The exiting surface P4 is inclined relative to the second reflecting surface P3 and closer to the incident surface P1. The imaging surface IMG of the image sensor is set relative to the exiting surface P4. The first reflecting surface P2 is provided with a reflective film. The angle θ1 between the first reflecting surface P2 and the second reflecting surface P3 is 30°. The angle θ2 between the incident surface P1 and the first reflecting surface P2 is 60°. The angle θ3 between the exiting surface P4 and the zero field principal ray is 90°. The aperture STO is set on the object side of the first lens L1. The filter IR is set between the exiting surface P4 and the imaging surface IMG.
[0064] The first lens L1 has positive optical power, with a convex object-side surface and a concave image-side surface. The second lens L2 has positive optical power, with a concave object-side surface and a convex image-side surface. The third lens L3 has negative optical power, with a concave object-side surface and a convex image-side surface. The fourth lens L4 has negative optical power, with a concave object-side surface and a convex image-side surface. The filter IR has an object-side surface and an image-side surface. Light rays pass sequentially through the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the incident surface P1 into the prism P. They are reflected by the first reflecting surface P2 to the second reflecting surface P3 (the first reflection), then reflected again by the second reflecting surface P3 to the exit surface P4 (the second reflection), and finally imaged onto the imaging surface IMG.
[0065] Table 3 shows the basic parameters of the telephoto lens in Example 2, where the units for radius of curvature, thickness, focal length, and effective aperture are all millimeters (mm).
[0066] Table 3:
[0067]
[0068] Table 4 shows the higher-order coefficients that can be used for each aspherical mirror in Example 2, wherein each aspherical surface shape can be defined by formula (1) given in Example 1 above.
[0069] Table 4:
[0070]
[0071] In Embodiment 2, light is reflected twice internally by the first reflecting surface P2 and the second reflecting surface P3 of the prism P before exiting to the imaging surface IMG. The back focal length of the lens is folded twice inside the prism P, resulting in a more compact structure, reduced overall height, and improved image quality. Simultaneously, the incident surface P1 is perpendicular to the second reflecting surface P3, and the imaging surface IMG is tilted to follow the exit surface P4. The image sensor is also tilted accordingly, which helps to correct the propagation path of light and further reduces the overall height. On the other hand, by reasonably allocating the optical power, spacing, and refractive index of the first lens L1 to the fourth lens L4 in the table above, a large target surface, large aperture, and short optical length can be achieved, which is beneficial for lens miniaturization. The appearance of electronic devices can be improved accordingly, and the user experience can be enhanced. The telephoto lens has a focal length of 15.36mm, an aperture of 2.5, an image circle diameter of 9.4mm, a field of view of 34°, and an operating wavelength of 420~680nm. The effective aperture of the image side of the fourth lens L4 is D10=4.89mm, the effective aperture of the incident surface P1 is D11=5.20mm, the effective aperture of the exit surface P4 is D12=13.52mm, the focal length of the first lens L1 is f1=7.8mm, and the focal length of the fourth lens L4 is f4=-9.27mm. The effective aperture D10 of the image-side surface of the fourth lens L4 is related to the effective aperture D11 of the incident surface P1 by D10 / D11 = 0.94; the effective aperture D11 of the incident surface P1 is related to the effective aperture D12 of the exit surface P4 by D11 / D12 = 0.38; the focal length f1 of the first lens L1 is related to the focal length f of the telephoto lens by f1 / f = 0.51; the focal length f4 of the fourth lens L4 is related to the focal length f of the telephoto lens by f4 / f = -0.60.
[0072] Figure 7The MTF curve of the telephoto lens in Example 2 is shown. The MTF (Modulation Transfer Function) curve shows the transmission of image details (i.e. image contrast) at different spatial frequencies by the imaging system. At a spatial frequency of 90 lp / mm, the MTF value is greater than 0.5, indicating good resolution and good imaging effect. Figure 8 The optical fan diagram of the telephoto lens of Example 2 is shown. The optical fan diagram typically shows the cross-section of the light beam at different positions, as well as the path and changes in the propagation of the beam in the optical system. It is a comprehensive evaluation diagram of various aberrations, with a scale of ±20µm, that is, the scale range in the horizontal and vertical directions is ±20µm, and various aberrations are well corrected. Figure 9 The diagram shows the relative illumination and Y-field of view of the telephoto lens in Example 2. The relative illumination is greater than 0.6, and the illumination is uniform. According to... Figures 7 to 9 It can be seen that the telephoto lens given in Example 2 has well corrected aberrations, uniform illumination and good resolution, and can achieve good image quality.
[0073] Example 3
[0074] The following is for reference Figure 10 This describes a telephoto lens according to Embodiment 3 of this application. In this embodiment, for the sake of brevity, descriptions similar to those in Embodiment 1 are omitted.
[0075] The telephoto lens of Embodiment 3, from the object side to the image side, includes: a lens assembly 10, a prism P, and an image sensor. The lens assembly 10 includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4 arranged in sequence. The prism P includes an incident surface P1 facing the fourth lens L4, a first reflecting surface P2, a second reflecting surface P3, and an exit surface P4 facing the image sensor. The first reflecting surface P2 is used to reflect light from the incident surface P1 for the first time and reflect it to the second reflecting surface P3. The second reflecting surface P3 is used to reflect light from the first reflecting surface P2 for the second time and reflect it to the exit surface P4. The incident surface P1... 1. Perpendicular to the second reflecting surface P3, the first reflecting surface P2 and the exiting surface P4 are on the same plane. The exiting surface P4 is inclined relative to the second reflecting surface P3 and closer to the incident surface P1. The imaging surface IMG of the image sensor is set relative to the exiting surface P4. The first reflecting surface P2 is provided with a reflective film. The angle θ1 between the first reflecting surface P2 and the second reflecting surface P3 is 30°. The angle θ2 between the incident surface P1 and the first reflecting surface P2 is 60°. The angle θ3 between the exiting surface P4 and the zero field principal ray is 90°. The aperture STO is set on the object side of the first lens L1. The filter IR is set between the exiting surface P4 and the imaging surface IMG.
[0076] The first lens L1 has positive optical power, with a convex object-side surface and a concave image-side surface. The second lens L2 has negative optical power, with a concave object-side surface and a concave image-side surface. The third lens L3 has positive optical power, with a convex object-side surface and a convex image-side surface. The fourth lens L4 has negative optical power, with a concave object-side surface and a convex image-side surface. The filter IR has an object-side surface and an image-side surface. Light rays pass sequentially through the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, and the incident surface P1 into the prism P. They are reflected by the first reflecting surface P2 to the second reflecting surface P3 (the first reflection), then reflected again by the second reflecting surface P3 to the exit surface P4 (the second reflection), and finally pass through the exit surface P4, ultimately forming an image on the imaging surface IMG.
[0077] Table 5 shows the basic parameters of the telephoto lens in Example 3, where the units for radius of curvature, thickness, focal length, and effective aperture are all millimeters (mm).
[0078] Table 5:
[0079]
[0080] Table 6 shows the higher-order coefficients that can be used for each aspherical mirror in Example 3, wherein each aspherical surface shape can be defined by formula (1) given in Example 1 above.
[0081] Table 6:
[0082]
[0083] In embodiment 3, light is reflected twice internally by the first reflecting surface P2 and the second reflecting surface P3 of the prism P before being emitted to the imaging surface IMG. The back focal length of the lens is folded twice inside the prism P, making the structure more compact, reducing the overall height and improving the image quality. At the same time, the incident surface P1 is perpendicular to the second reflecting surface P3, and the imaging surface IMG is tilted to follow the exit surface P4. The image sensor is also tilted accordingly, which helps to correct the propagation path of light and further reduces the overall height. On the other hand, by reasonably allocating the optical power, spacing and refractive index of the first lens L1 to the fourth lens L4 in the table above, the effect of a large target surface, a large aperture and a short optical length can be achieved, which is conducive to lens miniaturization, improves the appearance of electronic devices, and enhances the user experience. The telephoto lens has a focal length of f = 15.39mm, an aperture of f = 2.5, an image circle diameter of 9.4mm, a field of view of 34°, and an operating wavelength of 420~680nm. The effective aperture of the image side of the fourth lens L4 is D10 = 4.89mm, the effective aperture of the incident surface P1 is D11 = 5.16mm, the effective aperture of the exit surface P4 is D12 = 13.55mm, the focal length of the first lens L1 is f1 = 7.96mm, and the focal length of the fourth lens L4 is f4 = -9.27mm. The effective aperture D10 of the image-side surface of the fourth lens L4 is related to the effective aperture D11 of the incident surface P1 by D10 / D11 = 0.95; the effective aperture D11 of the incident surface P1 is related to the effective aperture D12 of the exit surface P4 by D11 / D12 = 0.38; the focal length f1 of the first lens L1 is related to the focal length f of the telephoto lens by f1 / f = 0.52; the focal length f4 of the fourth lens L4 is related to the focal length f of the telephoto lens by f4 / f = -0.60.
[0084] Figure 11 The MTF curve of the telephoto lens in Example 3 is shown. The MTF (Modulation Transfer Function) curve shows the transmission of image details (i.e. image contrast) at different spatial frequencies by the imaging system. At a spatial frequency of 90 lp / mm, the MTF value is greater than 0.5, indicating good resolution and good imaging effect. Figure 12 The optical fan diagram of the telephoto lens of Example 3 is shown. The optical fan diagram typically shows the cross-section of the light beam at different positions, as well as the path and changes in the propagation of the beam in the optical system. It is a comprehensive evaluation diagram of various aberrations, with a scale of ±20µm, that is, the scale range in the horizontal and vertical directions is ±20µm, and various aberrations are well corrected. Figure 13 The diagram shows the relative illumination and Y-field of view of the telephoto lens in Example 3. The relative illumination is greater than 0.6, and the illumination is uniform. According to... Figures 11 to 13As can be seen, the telephoto lens given in Example 3 has well-corrected aberrations, uniform illumination, and good resolution, and can achieve good image quality.
[0085] In summary, Examples 1, 2, and 3 satisfy the relationships shown in Table 7.
[0086] Table 7:
[0087]
[0088] 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, From the object side to the image side, the components are arranged in sequence as follows: a lens assembly (10), a prism (P), and an image sensor. The lens assembly (10) includes a plurality of lenses arranged in sequence. The prism (P) includes an incident surface (P1) facing the lens assembly (10), a first reflecting surface (P2), a second reflecting surface (P3), and an exit surface (P4) facing the image sensor. The first reflecting surface (P2) is used to reflect light from the incident surface (P1) for the first time and reflect it to the second reflecting surface (P3). The second reflecting surface (P3) is used to reflect light from the first reflecting surface (P2) for the second time and reflect it to the exit surface (P4). The incident surface (P1) is perpendicular to the second reflecting surface (P3). The first reflecting surface (P2) and the exit surface (P4) are on the same plane. The exit surface (P4) is inclined relative to the second reflecting surface (P3) and closer to the incident surface (P1). The imaging surface (IMG) of the image sensor is set relative to the exit surface (P4).
2. The telephoto lens of claim 1, wherein, The first reflective surface (P2) and / or the second reflective surface (P3) are provided with reflective films.
3. The telephoto lens of claim 1, wherein, The plurality of lenses includes a first lens (L1), a second lens (L2), a third lens (L3), and a fourth lens (L4). The incident surface (P1) is disposed facing the fourth lens (L4). The effective aperture D10 of the image-side surface of the fourth lens (L4) and the effective aperture D11 of the incident surface (P1) satisfy: 0.8 <D10 / D11<1.2。 4. The telephoto lens of claim 1, wherein, The effective aperture D11 of the incident surface (P1) and the effective aperture D12 of the exit surface (P4) satisfy: 0.2 <D11 / D12<0.5。 5. The telephoto lens of claim 1, wherein, The included angle θ1 between the first reflecting surface (P2) and the second reflecting surface (P3) satisfies: 25° < θ1 < 35°, and the included angle θ2 between the incident surface (P1) and the first reflecting surface (P2) satisfies: 50° < θ2 < 70°.
6. The telephoto lens of claim 1, wherein, The angle θ3 between the exit surface (P4) and the zero field of view principal ray is 90°.
7. The telephoto lens of claim 1, wherein, The plurality of lenses includes a first lens (L1), a second lens (L2), a third lens (L3), and a fourth lens (L4). The incident surface (P1) is positioned facing the fourth lens (L4). The focal length f1 of the first lens (L1) and the focal length f of the telephoto lens satisfy: 0.3 <f1 / f<0.6。 8. The telephoto lens of claim 1, wherein, The plurality of lenses includes a first lens (L1), a second lens (L2), a third lens (L3), and a fourth lens (L4). The incident surface (P1) is positioned facing the fourth lens (L4). The focal length f4 of the fourth lens (L4) and the focal length f of the telephoto lens satisfy: -0.9 <f4 / f<-0.5。 9. The telephoto lens of claim 1, wherein, The long-focus lens further comprises a stop (STO), the plurality of lenses comprising a first lens (L1), a second lens (L2), a third lens (L3) and a fourth lens (L4), the entrance face (P1) being arranged towards the fourth lens (L4), the stop (STO) being arranged on the object side of the first lens (L1).
10. An electronic device, comprising: A long-focus lens comprising any one of claims 1 to 9.