Optical systems, lens modules and terminal equipment

Abstract

The embodiments of the present application disclose an optical system, a lens module, and a terminal device. The optical system includes a first lens group with negative refractive power and a second lens group, a third lens group, and a fourth lens group with positive refractive power along the optical axis from the object side to the image side. The image side surface of the lens adjacent to the image side in the second lens group at the near optical axis is concave, and the object side surface of the lens adjacent to the object side in the third lens group at the near optical axis is concave. The fourth lens group includes at least two lenses, and at least one lens in the fourth lens group has negative refractive power. The refractive power and surface shape of the first to fourth lens groups are reasonably configured so that the optical system has high pixels and good imaging quality, can clearly capture imaging information, and meet the high-pixel image quality requirements of the optical system.

Description

Technical Field

[0001] The present invention belongs to the field of optical imaging technology, and in particular relates to an optical system, a lens module and a terminal device. Background Art

[0002] In recent years, in order to meet the growing market demand, mobile phones, surveillance, vehicle-mounted and other terminal devices have increasingly higher requirements for cameras, requiring not only miniaturization and lightweight, but also high pixels.

[0003] At present, with the development of terminal equipment, traditional optical systems generally have the problems of large size and high price, which cannot meet customers' requirements for small size, low price and high performance.

[0004] How to solve the problem of lens miniaturization, improve the pixel of the lens and meet the requirements of high-pixel image quality should be the research and development direction of the industry. Summary of the Invention

[0005] The embodiments of the present application provide an optical system, a lens module and a terminal device. The optical system has high pixels and good imaging quality, can clearly capture imaging information, and meets the requirements of high pixel image quality of the optical system.

[0006] In a first aspect, an embodiment of the present application provides an optical system, which includes, in sequence from the object side to the image side along the optical axis, a first lens group with negative refractive power and a second lens group, a third lens group, and a fourth lens group with positive refractive power; the image side surface of the lens adjacent to the image side in the second lens group is concave, wherein the lens adjacent to the image side refers to the lens closest to the image side in the second lens group; the object side surface of the lens adjacent to the object side in the third lens group is concave, wherein the lens adjacent to the object side refers to the lens closest to the object side in the third lens group; the fourth lens group includes at least two lenses, and at least one lens in the fourth lens group has negative refractive power; the optical system also includes a stop, which is located between the object side of the optical system and the object side surface of the third lens group.

[0007] The present application provides an optical system comprising four lens groups, namely a first lens group, a second lens group, a third lens group, and a fourth lens group. The lens groups of the optical system facilitate the elimination of aberrations within the lens groups and enable mutual correction between the lens groups. By rationally configuring the refractive power and surface shape of the first to fourth lens groups, the optical system achieves high pixel density and good imaging quality, while achieving a compact structure to meet the requirements of miniaturization.

[0008] In one embodiment, among all the lenses of the optical system, the object side surface and / or image side surface of at least one lens is aspherical, which is beneficial to correcting system aberrations and improving system imaging quality.

[0009] In one embodiment, the second lens group includes a second lens and a third lens, wherein the image side surface of the second lens is cemented to the object side surface of the third lens; and / or the third lens group includes a fourth lens and a fifth lens, wherein the image side surface of the fourth lens is cemented to the object side surface of the fifth lens. By arranging the second lens and the third lens to be cemented to form a cemented lens, and / or the fourth lens and the fifth lens to be cemented to form a cemented lens, it is advantageous to reduce the decentering sensitivity of the optical imaging system, improve the assembly yield, and reduce production costs. A cemented lens refers to two or more lenses bonded together using a photosensitive adhesive or the like.

[0010] In one embodiment, the object-side surface of the second lens at the near optical axis is convex, the image-side surface of the second lens at the near optical axis is convex, the object-side surface of the third lens at the near optical axis is concave, the image-side surface of the third lens at the near optical axis is concave, the object-side surface of the fourth lens at the near optical axis is concave, the image-side surface of the fourth lens at the near optical axis is concave, the object-side surface of the fifth lens at the near optical axis is convex, and the image-side surface of the fifth lens at the near optical axis is convex. By limiting the surface shapes of the second, third, fourth, and fifth lenses, it is advantageous to achieve a compact structure of the optical system and a high-pixel imaging effect.

[0011] In one embodiment, the lens adjacent to the object side of the fourth lens group is a sixth lens, the sixth lens having positive refractive power, the object-side surface of the sixth lens near the optical axis being convex, and the image-side surface of the sixth lens near the optical axis being convex. The lens adjacent to the image side of the fourth lens group is a seventh lens, the seventh lens having negative refractive power, the object-side surface of the seventh lens near the optical axis being concave, and the image-side surface of the seventh lens near the optical axis being convex. By limiting the refractive power and surface shape of the sixth and seventh lenses in the fourth lens group, a compact structure of the optical system and high-pixel imaging effects can be achieved.

[0012] In one embodiment, the optical system satisfies the conditional equation: 0.32 < Imgh / TTL < 0.46, where Imgh is the diagonal length of the effective pixel area of ​​the optical system, and TTL is the total length of the optical system (i.e., the distance from the object side of the first lens to the imaging plane on the optical axis in the optical system). By limiting the Imgh / TTL ratio, high-pixel imaging quality of the optical system is ensured, while also controlling the total length of the optical system, facilitating a compact structure for the optical system and miniaturization of the lens.

[0013] In one embodiment, the optical system satisfies the conditional formula: -3.8 < f1 / f < -1.3; the lens in the first position sorted from the object side to the image side is the first lens, f1 is the focal length of the first lens, and f is the effective focal length of the optical system. By defining the ratio range of f1 / f, the first lens adjacent to the object side is set as a negative lens to provide negative refractive power for the optical system, capture the light rays entering the optical system at large angles, increase the field angle range of the optical system to obtain a large field angle, and endow the optical system with the characteristics of low sensitivity and miniaturization.

[0014] In one embodiment, the optical system satisfies the conditional formula: 4 < |(SD S1) / (RDY S1)| * 100 < 9; SDS1 is half of the maximum effective aperture value of the object side surface of the first lens, and RDY S1 is the radius of curvature of the object side surface of the first lens. The magnitude of RDY S1 will affect the bending degree of the lens and the processing difficulty of the lens. When |(SD S1) / (RDY S1)| * 100 < 4, the greater the bending degree of the lens, the more it affects the processing of the lens. When |(SD S1) / (RDY S1)| * 100 > 9, the lens surface is smooth and it is easy to generate ghost images with other components with similar flat surfaces.

[0015] By defining the ratio range of f1 / f and the magnitude of RDY S1, it is beneficial to increase the field angle range of the optical system to obtain a large field angle, and on the basis of endowing the optical system with the characteristics of low sensitivity and miniaturization, reduce the probability of generating ghost images.

[0016] In one embodiment, the optical system satisfies the conditional formula: 0 < f23 / f < 5; the lens in the second position sorted from the object side to the image side is the second lens, and the lens in the third position sorted from the object side to the image side is the third lens. f23 is the combined focal length of the second lens and the third lens, and f is the effective focal length of the optical system. By defining a suitable ratio of f23 / f, it is beneficial to correct the chromatic aberration of the optical system, reduce the decentration sensitivity, correct the aberration of the optical system, improve the imaging resolution, and reduce the system assembly sensitivity, solve the problems of lens process manufacturing and lens assembly, and improve the yield.

[0017] In one embodiment, the optical system satisfies the conditional formula: 30 < |nd2 - nd3| * 100 < 60; the lens in the second position sorted from the object side to the image side is the second lens, and the lens in the third position sorted from the object side to the image side is the third lens. nd2 is the refractive index of the second lens, and nd3 is the refractive index of the third lens. Reasonably configuring the refractive indices of the second lens and the third lens included in the second lens group to ensure the refractive power of the second lens group is beneficial to correcting the system aberration and improving the imaging resolution of the optical system.

[0018] In one embodiment, the optical system satisfies the following condition: 0.5mm < D34 < 1.3mm; the lens in the third position from the object side to the image side is the third lens, the lens in the fourth position from the object side to the image side is the fourth lens, and D34 is the distance on the optical axis between the image side surface of the third lens and the object side surface of the fourth lens. Limiting the distance on the optical axis between the image side surface of the third lens and the object side surface of the fourth lens helps reduce assembly sensitivity, improve production yield, and make the optical system compact, meeting miniaturization requirements.

[0019] In one embodiment, the optical system satisfies the conditional equation: |nd4-nd5|*100<30; the lens in the fourth position from the object side to the image side is the fourth lens, the lens in the fifth position from the object side to the image side is the fifth lens, nd4 is the refractive index of the fourth lens, and nd5 is the refractive index of the fifth lens. Properly configuring the refractive indices of the fourth and fifth lenses helps reduce the probability of ghosting between the cemented surfaces of the fourth and fifth lenses.

[0020] In one embodiment, the optical system satisfies the following condition: 0.1 < D56 / f < 0.5; the lens ranked fifth from the object side to the image side is the fifth lens, the lens ranked sixth from the object side to the image side is the sixth lens, D56 is the distance on the optical axis between the image side of the fifth lens and the object side of the sixth lens, and f is the effective focal length of the optical system. By controlling the air gap between the fifth and sixth lenses, the position of the system imaging plane is controlled, ensuring the system has a wide viewing angle and a short overall system length, achieving a compact optical system structure, improving image quality, and extending the system's usability over a wide range of time and space.

[0021] In one embodiment, the optical system satisfies the conditional equation: 0 < f67 / f < 3; the lens ranked sixth from the object side to the image side is the sixth lens, the lens ranked seventh from the object side to the image side is the seventh lens, f67 is the combined focal length of the sixth and seventh lenses, and f is the effective focal length of the optical system. By limiting the f67 / f ratio, the fourth lens group can achieve a larger focal length, reducing sensitivity.

[0022] In one embodiment, the optical system satisfies the following conditions: nd4>1.65; nd7>1.65; vd4<55; vd7<55; the lens ranked fourth from the object side to the image side is the fourth lens, the lens ranked seventh from the object side to the image side is the seventh lens, nd4 is the refractive index of the fourth lens, nd7 is the refractive index of the seventh lens, vd4 is the Abbe number of the fourth lens, and vd7 is the Abbe number of the seventh lens. Limiting the ratio of the refractive indices and Abbe numbers of the fourth and seventh lenses facilitates correction of off-axis chromatic aberration of the system and improves the resolution of the optical system.

[0023] In one embodiment, the optical system satisfies the following condition: 3 < FOV / CRA < 16, where FOV is the diagonal field of view of the optical system, and CRA is the angle between the principal ray and the normal to the imaging surface at maximum image height. By limiting the ratio of the field of view angle to the principal ray incident angle, the optical system has a larger field of view, meeting the wide field of view requirements of mobile phones, surveillance cameras, and vehicle-mounted devices. Simultaneously, reducing the angle of the principal ray incident on the imaging surface can enhance the photosensitivity of the photosensitive element, thereby improving the imaging quality of the optical system.

[0024] In one embodiment, the optical system satisfies the conditional equation: 0.3 < ΣCT / TTL < 0.8; the lens ranked first from the object side to the image side is the first lens, the lens ranked seventh from the object side to the image side is the seventh lens, ΣCT is the sum of the thicknesses of the first through seventh lenses of the optical system on the optical axis, and TTL is the total length of the optical system (i.e., the distance from the object side of the first lens to the imaging plane on the optical axis in the optical system). By rationally configuring the center thickness of each lens, the total length of the optical system can be effectively shortened, ensuring a compact structure between the lenses.

[0025] In a second aspect, the present application provides a lens module, comprising a lens barrel and the optical system described in any one of the aforementioned embodiments, wherein the optical system is installed in the lens barrel.

[0026] In a third aspect, the present application provides a terminal device comprising the lens module.

[0027] The present application reasonably configures the refractive power and surface shape of the first lens group to the fourth lens group, so that the optical system has high pixels and good imaging quality, meets the requirements of miniaturization, and realizes a compact structure of the optical system. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the background technology, the drawings required for use in the embodiments of the present invention or the background technology will be described below.

[0029] Figure 1 is a schematic diagram of the optical system provided by this application applied in a terminal device;

[0030] Figure 2 is a schematic structural diagram of an optical system provided in the first embodiment of the present application;

[0031] Figure 3 is the spherical aberration curve of the optical system of the first embodiment;

[0032] Figure 4 is an astigmatism curve of the optical system of the first embodiment;

[0033] Figure 5 is a distortion curve of the optical system of the first embodiment;

[0034] Figure 6 is a schematic structural diagram of an optical system provided in a second embodiment of the present application;

[0035] Figure 7 is the spherical aberration curve of the optical system of the second embodiment;

[0036] Figure 8 is an astigmatism curve of the optical system of the second embodiment;

[0037] Figure 9 is a distortion curve of the optical system of the second embodiment;

[0038] Figure 10 is a schematic structural diagram of an optical system provided in the third embodiment of the present application;

[0039] Figure 11 is a spherical aberration curve of the optical system of the third embodiment;

[0040] Figure 12 is an astigmatism curve of the optical system of the third embodiment;

[0041] Figure 13 is a distortion curve of the optical system of the third embodiment;

[0042] Figure 14 is a schematic structural diagram of an optical system provided in a fourth embodiment of the present application;

[0043] Figure 15 is a spherical aberration curve of the optical system of the fourth embodiment;

[0044] Figure 16 is an astigmatism curve of the optical system of the fourth embodiment;

[0045] Figure 17 is a distortion curve of the optical system of the fourth embodiment. DETAILED DESCRIPTION

[0046] The embodiments of the present invention are described below with reference to the accompanying drawings.

[0047] See Figure 1 The optical system 10 involved in this application is applied to a lens module 20 in a terminal device 30. The terminal device 30 can be a mobile phone, a monitoring device, a vehicle-mounted device, etc. The optical system 10 is installed in the lens barrel of the lens module 20, and the lens module 20 is assembled inside the terminal device 30.

[0048] In one embodiment, the optical system provided herein includes seven lenses, which form four lens groups, arranged in order from the object side to the image side along the optical axis: a first lens group, a second lens group, a third lens group, and a fourth lens group. The number of lenses in the present application can also be six, eight, nine, and so on.

[0049] Specifically, the surface shapes and refractive powers of the four lens groups are as follows:

[0050] The first lens group has negative refractive power; the second lens group has positive refractive power, and the image side surface of the lens adjacent to the image side in the second lens group is concave, wherein the lens adjacent to the image side refers to the lens closest to the image side in the second lens group; the third lens group has positive refractive power, and the object side surface of the lens adjacent to the object side in the third lens group is concave, wherein the lens adjacent to the object side refers to the lens closest to the object side in the third lens group; the fourth lens group has positive refractive power, and the fourth lens group includes at least two lenses, and at least one lens in the fourth lens group has negative refractive power.

[0051] The optical system further includes a stop located between the object side of the optical system and the object side surface of the third lens group.

[0052] By rationally configuring the refractive power and surface shape of the first to fourth lens groups, the optical system has high pixels and good imaging quality, meets the requirements of miniaturization, and realizes a compact structure of the optical system.

[0053] Among all the lenses in the optical system, at least one lens has an aspheric object-side surface and / or image-side surface, which helps correct system aberrations and improve system imaging quality. Taking the sixth lens as an example, where both the object-side and image-side surfaces are aspheric, the aspheric curve equation for the sixth lens is as follows:

[0054]

[0055] Where Z is the distance from the corresponding point on the aspheric surface to the plane tangent to the vertex of the surface, r is the distance from the corresponding point on the aspheric surface to the optical axis, c is the curvature of the aspheric vertex, k is the cone constant, and Ai is the coefficient corresponding to the i-th higher-order term in the aspheric surface shape formula.

[0056] The present application is described in detail below through four specific embodiments.

[0057] Example 1

[0058] like Figure 2 As shown, the middle straight line represents the optical axis. The left side of the optical system is the object side, and the right side is the image side. In the optical system provided in this embodiment, along the optical axis from the object side to the image side are the first lens L1, the second lens L2, the third lens L3, the aperture STO, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the protective glass CG. Among them, the first lens L1 is the first lens group, the second lens L2 and the third lens L3 are configured as a cemented lens and form the second lens group, the fourth lens L4 and the fifth lens L5 are configured as a cemented lens and form the third lens group, and the sixth lens L6 and the seventh lens L7 are the fourth lens group. The lens groups of the optical system are conducive to eliminating aberrations within the lens groups and can achieve mutual correction between lens groups. The cemented lenses are conducive to reducing the decentration sensitivity of the optical imaging system, improving the assembly yield, and reducing production costs.

[0059] The first lens L1 has negative refractive power and is made of glass. Its object-side surface S1 is convex near the optical axis, and its image-side surface S2 is concave near the optical axis. Both are spherical.

[0060] The second lens L2 has positive refractive power and is made of glass. Its object-side surface S3 is convex near the optical axis, and its image-side surface S4 is also convex near the optical axis. Both are spherical.

[0061] The third lens L3 has negative refractive power and is made of glass. Its object-side surface S5 is concave near the optical axis, and its image-side surface S6 is also concave near the optical axis. Both are spherical.

[0062] The fourth lens L4 has negative refractive power and is made of glass. Its object-side surface S7 is concave near the optical axis, and its image-side surface S8 is also concave near the optical axis. Both are spherical surfaces.

[0063] The fifth lens L5 has positive refractive power and is made of glass. Its object-side surface S9 is convex near the optical axis, and its image-side surface S10 is also convex near the optical axis. Both are spherical surfaces.

[0064] The sixth lens L6 has positive refractive power and is made of glass. Its object-side surface S11 is convex near the optical axis, and its image-side surface S12 is convex near the optical axis. Both are aspherical.

[0065] The seventh lens L7 has negative refractive power and is made of glass. Its object-side surface S13 is concave near the optical axis, and its image-side surface S14 is convex near the optical axis. Both surfaces are spherical.

[0066] The aperture STO can be located between the object side of the optical system and the third lens group. In this embodiment, the aperture STO is located after the third lens L3, close to the middle position of the optical system, which is conducive to balancing the aberrations of the optical system.

[0067] Cover glass CG is located behind lens element L7 and includes object-side surface S15 and image-side surface S16. It protects the photosensitive element from exposure, shielding it from dust and other influences, and ensuring image quality. Imaging surface S17 is the active pixel area of ​​the electronic photosensitive element.

[0068] Table 1a shows the characteristics of the optical system of this embodiment, where the units of Y radius (ie, curvature radius), thickness, and focal length are all millimeters (mm).

[0069] Table 1a

[0070]

[0071]

[0072] Wherein, f is the effective focal length of the optical system, FNO is the aperture number of the optical system, and FOV is the field of view angle in the diagonal direction of the optical system.

[0073] S4 / S5 refers to the image-side surface of the second lens and the object-side surface of the third lens. The image-side surface S4 of the second lens and the object-side surface S5 of the third lens are glued together, so they are reflected as one surface in the data.

[0074] S8 / S9 refers to the image-side surface of the fourth lens and the object-side surface of the fifth lens. The image-side surface S8 of the fourth lens and the object-side surface S9 of the fifth lens are glued together, so they are reflected as one surface in the data.

[0075] Table 1b shows the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 that can be used for the aspherical mirror surfaces S11 and S12 in the first embodiment.

[0076] Table 1b

[0077] Surface number S11 S12 K 1.17E+00 -1.99E+00 A4 -1.07E-04 -4.87E-05 A6 -4.02E-07 1.46E-06 A8 0.00E+00 0.00E+00 A10 0.00E+00 0.00E+00 A12 0.00E+00 0.00E+00 A14 0.00E+00 0.00E+00 A16 0.00E+00 0.00E+00 A18 0.00E+00 0.00E+00 A20 0.00E+00 0.00E+00

[0078] Figure 3 The spherical aberration curve of the optical system of the first embodiment is shown, which indicates the deviation of the focal point of light of different wavelengths after passing through each lens of the optical system;

[0079] Figure 4 An astigmatism curve of the optical system of the first embodiment is shown, which indicates meridional field curvature and sagittal field curvature;

[0080] Figure 5The distortion curve of the optical system of the first embodiment is shown, which represents the distortion magnitude values ​​corresponding to different field angles;

[0081] according to Figure 3 、 Figure 4 and Figure 5 It can be seen that the optical system provided in the first embodiment can achieve good imaging quality.

[0082] Example 2

[0083] like Figure 6 As shown, the middle straight line represents the optical axis. The left side of the optical system is the object side, and the right side is the image side. In the optical system provided in this embodiment, along the optical axis from the object side to the image side are the first lens L1, the second lens L2, the third lens L3, the aperture STO, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the protective glass CG. Among them, the first lens L1 is the first lens group, the second lens L2 and the third lens L3 are configured as a cemented lens and form the second lens group, the fourth lens L4 and the fifth lens L5 are configured as a cemented lens and form the third lens group, and the sixth lens L6 and the seventh lens L7 are the fourth lens group. The lens groups of the optical system are conducive to eliminating aberrations within the lens groups and can achieve mutual correction between lens groups. The cemented lenses are conducive to reducing the decentration sensitivity of the optical imaging system, improving the assembly yield, and reducing production costs.

[0084] The first lens L1 has negative refractive power and is made of glass. Its object-side surface S1 is convex near the optical axis, and its image-side surface S2 is concave near the optical axis. Both are spherical.

[0085] The second lens L2 has positive refractive power and is made of glass. Its object-side surface S3 is convex near the optical axis, and its image-side surface S4 is also convex near the optical axis. Both are spherical surfaces.

[0086] The third lens L3 has negative refractive power and is made of glass. Its object-side surface S5 is concave near the optical axis, and its image-side surface S6 is also concave near the optical axis. Both are spherical.

[0087] The fourth lens L4 has negative refractive power and is made of glass. Its object-side surface S7 is concave near the optical axis, and its image-side surface S8 is also concave near the optical axis. Both are spherical surfaces.

[0088] The fifth lens L5 has positive refractive power and is made of glass. Its object-side surface S9 is convex near the optical axis, and its image-side surface S10 is also convex near the optical axis. Both are spherical surfaces.

[0089] The sixth lens L6 has positive refractive power and is made of glass. Its object-side surface S11 is convex near the optical axis, and its image-side surface S12 is convex near the optical axis. Both are aspherical.

[0090] The seventh lens L7 has negative refractive power and is made of glass. Its object-side surface S13 is concave near the optical axis, and its image-side surface S14 is convex near the optical axis. Both surfaces are spherical.

[0091] The other structures of the second embodiment are the same as those of the first embodiment, and can be referred to for reference.

[0092] Table 2a shows the characteristics of the optical system of this embodiment, where the units of Y radius (ie, curvature radius), thickness, and focal length are all in millimeters (mm).

[0093] Table 2a

[0094]

[0095]

[0096] Wherein, f is the effective focal length of the optical system, FNO is the aperture number of the optical system, and FOV is the field of view angle in the diagonal direction of the optical system.

[0097] S4 / S5 refers to the image-side surface of the second lens and the object-side surface of the third lens. The image-side surface S4 of the second lens and the object-side surface S5 of the third lens are glued together, so they are reflected as one surface in the data.

[0098] S8 / S9 refers to the image-side surface of the fourth lens and the object-side surface of the fifth lens. The image-side surface S8 of the fourth lens and the object-side surface S9 of the fifth lens are glued together, so they are reflected as one surface in the data.

[0099] Table 2b gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of the aspherical mirror surfaces S11 and S12 that can be used in the second embodiment.

[0100] Table 2b

[0101] Surface number S11 S12 K 1.58E+00 -1.77E+00 A4 -1.08E-04 -4.88E-05 A6 -9.37E-07 9.43E-07 A8 0.00E+00 0.00E+00 A10 0.00E+00 0.00E+00 A12 0.00E+00 0.00E+00 A14 0.00E+00 0.00E+00 A16 0.00E+00 0.00E+00 A18 0.00E+00 0.00E+00 A20 0.00E+00 0.00E+00

[0102] Figure 7 The spherical aberration curve of the optical system of the second embodiment is shown, which indicates the deviation of the focal point of light of different wavelengths after passing through each lens of the optical system;

[0103] Figure 8 An astigmatism curve of the optical system of the second embodiment is shown, which indicates meridional field curvature and sagittal field curvature;

[0104] Figure 9 The distortion curve of the optical system of the second embodiment is shown, which represents the distortion magnitude values ​​corresponding to different field angles;

[0105] according to Figure 7 、 Figure 8 and Figure 9 It can be seen that the optical system provided in the second embodiment can achieve good imaging quality.

[0106] Example 3

[0107] like Figure 10 As shown, the middle straight line represents the optical axis. The left side of the optical system is the object side, and the right side is the image side. In the optical system provided in this embodiment, along the optical axis from the object side to the image side are the first lens L1, the second lens L2, the third lens L3, the aperture STO, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the protective glass CG. Among them, the first lens L1 is the first lens group, the second lens L2 and the third lens L3 are configured as a cemented lens and form the second lens group, the fourth lens L4 and the fifth lens L5 are configured as a cemented lens and form the third lens group, and the sixth lens L6 and the seventh lens L7 are the fourth lens group. The lens groups of the optical system are conducive to eliminating aberrations within the lens groups and can achieve mutual correction between lens groups. The cemented lenses are conducive to reducing the decentration sensitivity of the optical imaging system, improving the assembly yield, and reducing production costs.

[0108] The first lens L1 has negative refractive power and is made of glass. Its object-side surface S1 is convex near the optical axis, and its image-side surface S2 is concave near the optical axis. Both are spherical.

[0109] The second lens L2 has positive refractive power and is made of glass. Its object-side surface S3 is convex near the optical axis, and its image-side surface S4 is also convex near the optical axis. Both are spherical.

[0110] The third lens L3 has negative refractive power and is made of glass. Its object-side surface S5 is concave near the optical axis, and its image-side surface S6 is also concave near the optical axis. Both are spherical.

[0111] The fourth lens L4 has negative refractive power and is made of glass. Its object-side surface S7 is concave near the optical axis, and its image-side surface S8 is also concave near the optical axis. Both are spherical surfaces.

[0112] The fifth lens L5 has positive refractive power and is made of glass. Its object-side surface S9 is convex near the optical axis, and its image-side surface S10 is also convex near the optical axis. Both are spherical surfaces.

[0113] The sixth lens L6 has positive refractive power and is made of glass. Its object-side surface S11 is convex near the optical axis, and its image-side surface S12 is convex near the optical axis. Both are aspherical.

[0114] The seventh lens L7 has negative refractive power and is made of glass. Its object-side surface S13 is concave near the optical axis, and its image-side surface S14 is convex near the optical axis. Both surfaces are spherical.

[0115] The other structures of the third embodiment are the same as those of the first embodiment, and can be referred to for reference.

[0116] Table 3a shows the characteristics of the optical system of this embodiment, where the units of Y radius (ie, curvature radius), thickness, and focal length are all in millimeters (mm).

[0117] Table 3a

[0118]

[0119] Wherein, f is the effective focal length of the optical system, FNO is the aperture number of the optical system, and FOV is the field of view angle in the diagonal direction of the optical system.

[0120] S4 / S5 refers to the image-side surface of the second lens and the object-side surface of the third lens. The image-side surface S4 of the second lens and the object-side surface S5 of the third lens are glued together, so they are reflected as one surface in the data.

[0121] S8 / S9 refers to the image-side surface of the fourth lens and the object-side surface of the fifth lens. The image-side surface S8 of the fourth lens and the object-side surface S9 of the fifth lens are glued together, so they are reflected as one surface in the data.

[0122] Table 3b gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of the aspherical mirror surfaces S11 and S12 that can be used in the third embodiment.

[0123] Table 3b

[0124]

[0125]

[0126] Figure 11 The spherical aberration curve of the optical system of the third embodiment is shown, which indicates the deviation of the focal point of light of different wavelengths after passing through each lens of the optical system;

[0127] Figure 12 An astigmatism curve of the optical system of the third embodiment is shown, which indicates meridional field curvature and sagittal field curvature;

[0128] Figure 13 The distortion curve of the optical system of the third embodiment is shown, which represents the distortion magnitude values ​​corresponding to different field angles;

[0129] according to Figure 11 、 Figure 12 and Figure 13 It can be seen that the optical system provided in the third embodiment can achieve good imaging quality.

[0130] Example 4

[0131] like Figure 14 As shown, the middle straight line represents the optical axis. The left side of the optical system is the object side, and the right side is the image side. In the optical system provided in this embodiment, along the optical axis from the object side to the image side are the first lens L1, the second lens L2, the third lens L3, the aperture STO, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the protective glass CG. Among them, the first lens L1 is the first lens group, the second lens L2 and the third lens L3 are configured as a cemented lens and form the second lens group, the fourth lens L4 and the fifth lens L5 are configured as a cemented lens and form the third lens group, and the sixth lens L6 and the seventh lens L7 are the fourth lens group. The lens groups of the optical system are conducive to eliminating aberrations within the lens groups and can achieve mutual correction between lens groups. The cemented lenses are conducive to reducing the decentration sensitivity of the optical imaging system, improving the assembly yield, and reducing production costs.

[0132] The first lens L1 has negative refractive power and is made of glass. Its object-side surface S1 is convex near the optical axis, and its image-side surface S2 is concave near the optical axis. Both are spherical.

[0133] The second lens L2 has positive refractive power and is made of glass. Its object-side surface S3 is convex near the optical axis, and its image-side surface S4 is also convex near the optical axis. Both are spherical.

[0134] The third lens L3 has negative refractive power and is made of glass. Its object-side surface S5 is concave near the optical axis, and its image-side surface S6 is also concave near the optical axis. Both are spherical.

[0135] The fourth lens L4 has negative refractive power and is made of glass. Its object-side surface S7 is concave near the optical axis, and its image-side surface S8 is also concave near the optical axis. Both are spherical surfaces.

[0136] The fifth lens L5 has positive refractive power and is made of glass. Its object-side surface S9 is convex near the optical axis, and its image-side surface S10 is also convex near the optical axis. Both are spherical surfaces.

[0137] The sixth lens L6 has positive refractive power and is made of glass. Its object-side surface S11 is convex near the optical axis, and its image-side surface S12 is convex near the optical axis. Both are aspherical.

[0138] The seventh lens L7 has negative refractive power and is made of glass. Its object-side surface S13 is concave near the optical axis, and its image-side surface S14 is convex near the optical axis. Both surfaces are spherical.

[0139] The other structures of the fourth embodiment are the same as those of the first embodiment, and can be referred to for reference.

[0140] Table 4a shows the characteristics of the optical system of this embodiment, where the units of Y radius (ie, curvature radius), thickness, and focal length are all in millimeters (mm).

[0141] Table 4a

[0142]

[0143] Wherein, f is the effective focal length of the optical system, FNO is the aperture number of the optical system, and FOV is the field of view angle in the diagonal direction of the optical system.

[0144] S4 / S5 refers to the image-side surface of the second lens and the object-side surface of the third lens. The image-side surface S4 of the second lens and the object-side surface S5 of the third lens are glued together, so they are reflected as one surface in the data.

[0145] S8 / S9 refers to the image-side surface of the fourth lens and the object-side surface of the fifth lens. The image-side surface S8 of the fourth lens and the object-side surface S9 of the fifth lens are glued together, so they are reflected as one surface in the data.

[0146] Table 4b gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of the aspherical mirror surfaces S11 and S12 that can be used in the fourth embodiment.

[0147] Table 4b

[0148] Surface number S11 S12 K 1.12E+00 -1.90E+00 A4 -1.13E-04 -9.14E-06 A6 -4.56E-07 7.86E-07 A8 0.00E+00 0.00E+00 A10 0.00E+00 0.00E+00 A12 0.00E+00 0.00E+00 A14 0.00E+00 0.00E+00 A16 0.00E+00 0.00E+00 A18 0.00E+00 0.00E+00 A20 0.00E+00 0.00E+00

[0149] Figure 15 The spherical aberration curve of the optical system of the fourth embodiment is shown, which indicates the deviation of the focal point of light of different wavelengths after passing through each lens of the optical system;

[0150] Figure 16 An astigmatism curve of the optical system of the fourth embodiment is shown, which indicates meridional field curvature and sagittal field curvature;

[0151] Figure 17 The distortion curve of the optical system of the fourth embodiment is shown, which represents the distortion magnitude values ​​corresponding to different field angles;

[0152] according to Figure 15 、 Figure 16 and Figure 17 It can be seen that the optical system provided in the fourth embodiment can achieve good imaging quality.

[0153] Table 5 shows the Imgh / TTL values ​​of the optical systems of the first to fourth embodiments. It can be seen from Table 5 that each embodiment satisfies the condition: 0.32<Imgh / TTL<0.46.

[0154] Table 5

[0155] Imgh / TTL First embodiment 0.34 Second embodiment 0.34 Third embodiment 0.34 Fourth embodiment 0.34

[0156] Table 6 shows the FOV / CRA values ​​of the optical systems of the first to fourth embodiments. As can be seen from Table 6, each embodiment satisfies the condition: 3<FOV / CRA<16.

[0157] Table 6

[0158] FOV / CRA First embodiment 7.17 Second embodiment 5.97 Third embodiment 5.98 Fourth embodiment 5.98

[0159] Table 7 shows the f1 / f values ​​of the optical systems of the first to fourth embodiments. It can be seen from Table 7 that each embodiment meets the condition: -3.8 <f1 / f<-1.3。

[0160] Table 7

[0161] f1 / f First embodiment -1.33 Second embodiment -1.32 Third embodiment -1.35 Fourth embodiment -1.34

[0162] Table 8 shows the values ​​of |((SD S1) / (RDY S1))|*100 of the optical systems of the first to fourth embodiments. It can be seen from Table 8 that each embodiment satisfies the condition: 4<|(SD S1) / (RDY S1)|*100<9.

[0163] Table 8

[0164] |(SD S1) / (RDY S1)|*100 First embodiment 8.37 Second embodiment 8.55 Third embodiment 5.20 Fourth embodiment 4.57

[0165] Table 9 shows the f23 / f values ​​of the optical systems of the first to fourth embodiments. It can be seen from Table 9 that each embodiment satisfies the condition: 0<f23 / f<5.

[0166] Table 9

[0167] f23 / f First embodiment 1.82 Second embodiment 1.76 Third embodiment 1.82 Fourth embodiment 1.81

[0168] Table 10 shows the values ​​of |nd2-nd3|*100 of the optical systems of the first to fourth embodiments. It can be seen from Table 10 that each embodiment satisfies the condition: 30<|nd2-nd3|*100<60.

[0169] Table 10

[0170] |nd2-nd3|*100 First embodiment 48.00 Second embodiment 48.40 Third embodiment 50.60 Fourth embodiment 49.00

[0171] Table 11 shows the D34 values ​​of the optical systems of the first to fourth embodiments. As can be seen from Table 11, each embodiment satisfies the condition: 0.5<D34<1.3.

[0172] Table 11

[0173] D34 First embodiment 0.83 Second embodiment 0.52 Third embodiment 0.85 Fourth embodiment 0.71

[0174] Table 12 shows the f67 / f values ​​of the optical systems of the first to fourth embodiments. It can be seen from Table 12 that each embodiment satisfies the condition: 0<f67 / f<3.

[0175] Table 12

[0176] f67 / f First embodiment 1.58 Second embodiment 1.59 Third embodiment 1.56 Fourth embodiment 1.60

[0177] Table 13 shows the ΣCT / TTL values ​​of the optical systems of the first to fourth embodiments. It can be seen from Table 13 that each embodiment satisfies the condition: 0.3<ΣCT / TTL<0.8.

[0178] Table 13

[0179] ΣCT / TTL First embodiment 0.51 Second embodiment 0.52 Third embodiment 0.54 Fourth embodiment 0.52

[0180] Table 14 shows the D56 / f values ​​of the optical systems of the first to fourth embodiments. It can be seen from Table 14 that each embodiment satisfies the condition: 0.1<D56 / f<0.5.

[0181] Table 14

[0182] D56 / f First embodiment 0.34 Second embodiment 0.26 Third embodiment 0.23 Fourth embodiment 0.29

[0183] Table 15 shows the nd4; nd7 and vd4; vd7 values ​​of the optical systems of the first to fourth embodiments. It can be seen from Table 15 that each embodiment meets the conditions: nd4; nd7>1.65vd4; vd7<55.

[0184] Table 15

[0185]

[0186]

[0187] Table 16 shows the values ​​of |nd4-nd5|*100 of the optical systems of the first to fourth embodiments. It can be seen from Table 16 that each embodiment satisfies the condition: |nd4-nd5|*100<30.

[0188] Table 16

[0189] |nd4-nd5|*100 First embodiment 12.0 Second embodiment 6.3 Third embodiment 13.1 Fourth embodiment 13.1

[0190] The above is a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications are also considered to be within the scope of protection of the present application.

Claims

1. An optical system, characterized in that: Along the optical axis from the object side to the image side, there are: A first lens group includes a first lens having negative refractive power; a second lens group having positive refractive power, the second lens group comprising a second lens and a third lens arranged in sequence from the object side to the image side, the second lens having positive refractive power, the third lens having negative refractive power, and the image side surface of the third lens being concave at a near optical axis; a third lens group having positive refractive power, the third lens group comprising a fourth lens and a fifth lens arranged in sequence from the object side to the image side, the fourth lens having negative refractive power, the object-side surface of the fourth lens being concave near the optical axis, and the fifth lens having positive refractive power; a fourth lens group having positive refractive power, the fourth lens group comprising a sixth lens and a seventh lens arranged in sequence from the object side to the image side, the sixth lens having positive refractive power, and the seventh lens having negative refractive power; The optical system is composed of the above seven lenses with optical power; The optical system satisfies the conditional formula: 3<FOV / CRA<16; FOV is the field of view angle of the optical system in the diagonal direction, and CRA is the angle between the principal ray at the maximum image height and the normal direction of the imaging surface.

2. The optical system according to claim 1, wherein: Among all the lenses of the optical system, the object-side surface and / or the image-side surface of at least one lens is aspherical.

3. The optical system according to claim 1, wherein: The image-side surface of the second lens is cemented to the object-side surface of the third lens; and / or the image-side surface of the fourth lens is cemented to the object-side surface of the fifth lens.

4. The optical system according to claim 3, wherein: The object side surface of the second lens at the near optical axis is convex, the image side surface of the second lens at the near optical axis is convex, the object side surface of the third lens at the near optical axis is concave, the image side surface of the fourth lens at the near optical axis is concave, the object side surface of the fifth lens at the near optical axis is convex, and the image side surface of the fifth lens at the near optical axis is convex.

5. The optical system according to claim 1, wherein: The sixth lens has positive refractive power, the object side surface of the sixth lens at the near optical axis is convex, the image side surface of the sixth lens at the near optical axis is convex, the object side surface of the seventh lens at the near optical axis is concave, and the image side surface of the seventh lens at the near optical axis is convex.

6. The optical system according to any one of claims 1 to 5, characterized in that The optical system satisfies the conditional formula: 0.32<Imgh / TTL<0.46; Imgh is the diagonal length of the effective pixel area of ​​the optical system, and TTL is the total length of the optical system.

7. The optical system according to any one of claims 1 to 5, characterized in that The optical system satisfies the conditional formula: -3.8 <f1 / f<-1.3; The lens at the first position arranged from the object side to the image side is the first lens, f1 is the focal length of the first lens, and f is the effective focal length of the optical system.

8. The optical system according to claim 1, wherein: The optical system satisfies the conditional formula: 4<|(SD S1) / (RDY S1)|*100<9; The lens arranged in the first position from the object side to the image side is the first lens, SD S1 is half of the maximum effective aperture value of the object side surface of the first lens, and RDY S1 is the curvature radius of the object side surface of the first lens.

9. The optical system according to any one of claims 1 to 5, characterized in that The optical system satisfies the conditional formula: 0<f23 / f<5; The lens in the second position from the object side to the image side is the second lens, the lens in the third position from the object side to the image side is the third lens, f23 is the combined focal length of the second lens and the third lens, and f is the effective focal length of the optical system.

10. The optical system according to any one of claims 1 to 5, characterized in that The optical system satisfies the conditional formula: 30<|nd2-nd3|*100<60; The lens in the second position from the object side to the image side is the second lens, the lens in the third position from the object side to the image side is the third lens, nd2 is the refractive index of the second lens, and nd3 is the refractive index of the third lens.

11. The optical system according to any one of claims 1 to 5, characterized in that The optical system satisfies the conditional formula: 0.5mm<D34<1.3mm; The lens in the third position from the object side to the image side is the third lens, the lens in the fourth position from the object side to the image side is the fourth lens, and D34 is the distance on the optical axis between the image side surface of the third lens and the object side surface of the fourth lens.

12. The optical system according to any one of claims 1 to 5, characterized in that The optical system satisfies the conditional formula: |nd4-nd5|*100<30; The lens at the fourth position from the object side to the image side is the fourth lens, the lens at the fifth position from the object side to the image side is the fifth lens, nd4 is the refractive index of the fourth lens, and nd5 is the refractive index of the fifth lens.

13. The optical system according to any one of claims 1 to 5, characterized in that The optical system satisfies the conditional formula: 0.1<D56 / f<0.5; The lens ranked fifth from the object side to the image side is the fifth lens, the lens ranked sixth from the object side to the image side is the sixth lens, D56 is the distance on the optical axis between the image side surface of the fifth lens and the object side surface of the sixth lens, and f is the effective focal length of the optical system.

14. The optical system according to any one of claims 1 to 5, characterized in that The optical system satisfies the conditional formula: 0<f67 / f<3; The lens at the sixth position from the object side to the image side is the sixth lens, the lens at the seventh position from the object side to the image side is the seventh lens, f67 is the combined focal length of the sixth lens and the seventh lens, and f is the effective focal length of the optical system.

15. The optical system according to any one of claims 1 to 5, characterized in that The optical system satisfies the conditional formula: nd4>1.65; nd7>1.65; vd4<55; vd7<55; The lens at the fourth position from the object side to the image side is the fourth lens, the lens at the seventh position from the object side to the image side is the seventh lens, nd4 is the refractive index of the fourth lens, nd7 is the refractive index of the seventh lens, vd4 is the Abbe number of the fourth lens, and vd7 is the Abbe number of the seventh lens.

16. The optical system according to any one of claims 1 to 5, characterized in that The object side surface of the first lens is convex at the near optical axis, and the image side surface of the first lens is concave at the near optical axis.

17. The optical system according to any one of claims 1 to 5, characterized in that The optical system satisfies the conditional formula: 0.3<ΣCT / TTL<0.8; The lens at the first position from the object side to the image side is the first lens, the lens at the seventh position from the object side to the image side is the seventh lens, ΣCT is the sum of the thicknesses of the first to seventh lenses of the optical system on the optical axis, and TTL is the total length of the optical system.

18. A lens module, characterized in that: It comprises a lens barrel and an optical system as claimed in any one of claims 1 to 17, wherein the optical system is installed in the lens barrel.

19. A terminal device, characterized in that: Comprising the lens module as described in claim 18.

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