Optical System, Imaging Device, and Electronic Device

Abstract

The present application discloses an optical system, which sequentially includes, from the object side to the image side along the optical axis: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens. The first lens has a negative refractive power, its object side is convex, and its image side is concave; the second lens has a positive refractive power, its object side is convex, and its image side is convex; the third lens has a negative refractive power, its object side is concave, and its image side is concave; the fourth lens has a positive refractive power; the fifth lens has a positive refractive power; the sixth lens has a negative refractive power, and its object side is concave; a diaphragm is disposed between the second lens and the third lens; the optical system satisfies the following relationship: f / D ≤ 1.6; where D is the entrance pupil diameter of the optical system, and f is the effective focal length of the optical system. The present application also relates to an imaging device and an electronic device.

Description

Technical Field

[0001] The present invention relates to the field of optical imaging technologies, and particularly to an optical system, an image pickup device, and an electronic device. Background Art

[0002] With the development of science and technology, the market demand for vehicle-mounted or surveillance camera lenses with high imaging quality is gradually increasing. Generally, lenses with a smaller F-number can collect more light information, have smaller optical aberrations, and better imaging quality. Therefore, such lenses are gradually favored by the market.

[0003] However, the inventors have found that in existing vehicle-mounted cameras and surveillance cameras, the F-number of the lens is usually large and the imaging effect is not good. Especially in the case of insufficient light (such as rainy days, dusk, etc.) or when the vehicle or the bracket shakes, the F-number of traditional vehicle-mounted and surveillance cameras can no longer meet the higher imaging requirements. Summary of the Invention

[0004] Based on this, in view of the problem of the large F-number and low imaging performance of traditional vehicle-mounted cameras, it is necessary to provide an improved optical system.

[0005] An optical system sequentially includes, from the object side to the image side along the optical axis: a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens, wherein,

[0006] The first lens has a negative refractive power, its object side surface is convex, and its image side surface is concave;

[0007] The second lens has a positive refractive power, its object side surface is convex, and its image side surface is convex;

[0008] The third lens has a negative refractive power, its object side surface is concave, and its image side surface is concave;

[0009] The fourth lens has a positive refractive power;

[0010] The fifth lens has a positive refractive power;

[0011] The sixth lens has a negative refractive power, and its object side surface is concave;

[0012] An aperture stop is disposed between the second lens and the third lens;

[0013] The optical system satisfies the following relational expression: f / D ≤ 1.6;

[0014] Wherein, f is the effective focal length of the optical system, and D is the entrance pupil diameter of the optical system.

[0015] For the above optical system, by reasonably distributing the refractive power, surface shape of each lens, and the spacing between each lens, the optical system can have a large aperture (i.e., a small F number), increase the light passing amount of the optical system, and further achieve a clear and bright imaging effect on the object to be photographed.

[0016] In one embodiment, among the lenses sequentially arranged from the object side to the image side along the optical axis, at least one lens has a planar object side or image side.

[0017] By setting the object side or image side of at least one lens among the lenses sequentially arranged from the object side to the image side to be planar, on the one hand, it is beneficial to lens processing, and on the other hand, since the curvature at the planar part is zero, the sensitivity of the optical system can be reduced, and the assembly yield of the lens can be improved.

[0018] In one embodiment, the object side of the fifth lens is spherical or aspherical, and the image side of the fifth lens is spherical or aspherical.

[0019] By setting the object side of the fifth lens to be spherical or aspherical and the image side to be spherical or aspherical, that is, neither the object side nor the image side of the fifth lens is planar, it is beneficial to correct the aberration of the optical system and improve the edge resolution of the image formed by the optical system.

[0020] In one embodiment, the optical system satisfies the following relationship:

[0021] 1 < L / f < 5; where L is the distance from the object side of the first lens to the imaging surface of the optical system on the optical axis, and f is the effective focal length of the optical system.

[0022] By controlling the distance from the object side of the first lens to the imaging surface of the optical system on the optical axis to satisfy the above relationship with the effective focal length of the optical system, the overall length of the optical system can be prevented from being too long, and at the same time, the effective focal length of the optical system can also be prevented from being too long, which is beneficial to achieving the miniaturization and wide-angleization of the lens.

[0023] In one embodiment, the refractive index Nd3 and Abbe number Vd3 of the third lens respectively satisfy Nd3 > 1.9, Vd3 < 30; the refractive index Nd6 and Abbe number Vd6 of the sixth lens respectively satisfy Nd6 > 1.9, Vd6 < 30.

[0024] Using materials that satisfy the above refractive index relationship and Abbe number relationship to prepare the third lens and the sixth lens is beneficial to correcting the axial chromatic aberration and lateral chromatic aberration of the optical system and improving the imaging quality.

[0025] In one embodiment, the optical system satisfies the following relationship: -2 < R8 / f < -0.5; where R8 is the radius of curvature of the image side of the fourth lens, and f is the effective focal length of the optical system.

[0026] By controlling the radius of curvature of the image side of the fourth lens and the effective focal length of the optical system to satisfy the above relationship, it is beneficial to correct the image plane curvature and spherical aberration of the optical system.

[0027] In one embodiment, the optical system satisfies the following relationship: f456 / f > 0.5; where f456 is the combined focal length of the fourth lens, the fifth lens, and the sixth lens, and f is the effective focal length of the optical system.

[0028] By controlling the combined focal length of the fourth lens, the fifth lens, and the sixth lens and the effective focal length of the optical system to satisfy the above relationship, it is beneficial to further correct the image plane curvature of the optical system, and at the same time, it can also increase the optical back focal length of the optical system, thereby facilitating the installation of a filter and a protective glass between the sixth lens and the imaging plane.

[0029] In one embodiment, the optical system satisfies the following relationship: FOV / CRA > 5; where FOV is the horizontal field of view angle of the optical system, and CRA is the chief ray angle of incidence of the optical system.

[0030] By controlling the horizontal field of view angle of the optical system and the chief ray angle of incidence of the optical system to satisfy the above relationship, it is possible to increase the horizontal field of view angle of the optical system to meet the wide-angle shooting requirements of electronic products such as mobile phones and cameras, and at the same time, it is also possible to reduce the chief ray angle of incidence of the optical system to improve the photosensitive performance of the optical system and improve the imaging effect.

[0031] In one embodiment, the optical system satisfies the following relationship: 0.5 < R2 / f < 1.5; where R2 is the radius of curvature of the image side of the first lens, and f is the effective focal length of the optical system.

[0032] By controlling the radius of curvature of the image side of the first lens and the effective focal length of the optical system to satisfy the above relationship, it is beneficial to correct the distortion of the optical system and to achieve the wide-angleization of the optical system; at the same time, as the radius of curvature of the image side of the first lens decreases, the difficulty of lens processing and coating will also increase. Therefore, by controlling the radius of curvature of the image side of the first lens within a reasonable range through the above relationship, the difficulty of lens processing and coating can be reduced, the production yield of the lens can be improved, and the production cost can be reduced.

[0033] In one embodiment, the optical system satisfies the following relational expression: 3 < (D34 / f) * 100 < 6; where D34 is the distance on the optical axis from the image side surface of the third lens to the object side surface of the fourth lens, and f is the effective focal length of the optical system.

[0034] By controlling the distance on the optical axis from the image side surface of the third lens to the object side surface of the fourth lens to satisfy the above relationship with the effective focal length of the optical system, the overall length of the optical system can be effectively reduced, and miniaturization of the lens can be achieved.

[0035] The present application also provides an image pickup device.

[0036] An image pickup device includes the optical system as described above; and an image sensor, where the image sensor is disposed on the image side of the optical system to receive light carrying image information formed by the optical system.

[0037] For the above image pickup device, by using the optical system with a small F-number, a clear and bright image can be obtained. At the same time, the overall length of the image pickup device is small and the production yield is high, which is beneficial to achieving miniaturization and reducing production costs.

[0038] The present application also provides an electronic device.

[0039] An electronic device includes a housing; and the image pickup device as described above, where the image pickup device is mounted on the housing to acquire images.

[0040] For the above electronic device, by using the image pickup device as described above, an image with a prominent subject, clear and bright can be captured, meeting the shooting requirements of in-vehicle cameras or surveillance cameras. Description of the Drawings

[0041] Figure 1 Shows a schematic structural diagram of the optical system according to Embodiment 1 of the present application;

[0042] Figures 2A to 2C Respectively are the longitudinal spherical aberration curve graph, astigmatism curve graph, and distortion curve graph of the optical system according to Embodiment 1;

[0043] Figure 3 Shows a schematic structural diagram of the optical system according to Embodiment 2 of the present application;

[0044] Figures 4A to 4C Respectively are the longitudinal spherical aberration curve graph, astigmatism curve graph, and distortion curve graph of the optical system according to Embodiment 2;

[0045] Figure 5 Shows a schematic structural diagram of the optical system according to Embodiment 3 of the present application;

[0046] Figures 6A to 6CThey are respectively the longitudinal spherical aberration curve graph, the astigmatism curve graph, and the distortion curve graph of the optical system of Embodiment 3. Detailed implementation manners

[0047] For the convenience of understanding the present invention, the present invention will be described more comprehensively below with reference to the relevant drawings. Preferred embodiments of the present invention are shown in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the disclosure of the present invention more thorough and comprehensive.

[0048] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "left", "right", "up", "down", "front", "rear", "circumferential" and similar expressions used herein are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation of the present invention.

[0049] It should be noted that in this specification, the expressions such as first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the features. Therefore, without departing from the teachings of the present application, the first lens discussed below can also be referred to as the second lens or the third lens.

[0050] For the convenience of description, the shapes of the spherical surfaces or aspherical surfaces shown in the drawings are shown by way of example. That is, the shapes of the spherical surfaces or aspherical surfaces are not limited to the spherical surfaces or aspherical surfaces shown in the drawings. The drawings are only examples and are not drawn strictly to scale.

[0051] In this article, if the lens surface is convex and the position of the convex surface is not defined, it means that the lens surface is convex at least in the paraxial region; if the lens surface is concave and the position of the concave surface is not defined, it means that the lens surface is concave at least in the paraxial region. The paraxial region here refers to the region near the optical axis. The surface of each lens closest to the object is called the object side surface, and the surface of each lens closest to the imaging surface is called the image side surface.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0053] Traditional vehicle-mounted or surveillance lenses usually have a large F number and low imaging performance. In addition, in response to the market demand for miniaturization and low cost, vehicle-mounted or surveillance lenses are usually equipped with plastic aspherical lenses, but plastic lenses have poor temperature compensation and cannot maintain ideal imaging effects in harsh environments.

[0054] The above defects are the results obtained by the inventor after practice and careful research. Therefore, the discovery process of the above problems and the solutions proposed in the embodiments of the present application for the above problems below should be the contributions made by the inventor to the present application during the application process. The features, principles and other aspects of the present application are described in detail below.

[0055] Please also read Figure 1 , Figure 3 and Figure 5 The optical system of the embodiment of the present application includes six lenses with refractive power, namely a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens. The six lenses are arranged in sequence from the object side to the image side along the optical axis.

[0056] The first lens has negative refractive power, its object side surface is convex, and its image side surface is concave; the second lens has positive refractive power, its object side surface is convex, and its image side surface is convex; the third lens has negative refractive power, and its object side surface is concave, and its image side surface is concave; the fourth lens has positive refractive power; the fifth lens has positive refractive power; the sixth lens has negative refractive power, and its object side surface is concave.

[0057] A stop is also provided between the second lens and the third lens to further improve the imaging quality of the optical system. The stop can be an aperture stop or a field stop.

[0058] Specifically, the optical system satisfies the following relationship: f / D≤1.6, wherein f is the effective focal length of the optical system, and D is the entrance pupil diameter of the optical system.

[0059] When the above optical system is used for imaging, the light emitted or reflected by the object enters the optical system from the object side direction, and sequentially passes through the first lens, the second lens, the third lens, the fourth lens, the fifth lens, and the sixth lens, and finally converges on the imaging surface. By controlling the effective focal length of the optical system and the entrance pupil diameter of the optical system to satisfy the above relationship, the F-number of the optical system can be effectively reduced, so the light transmission amount of the optical system can be increased, so that more light emitted or reflected by the object converges to the imaging surface, and finally a clear and bright image with prominent main body is formed.

[0060] In an exemplary embodiment, among the lenses sequentially arranged from the object side to the image side along the optical axis, at least one lens has a plane object side surface or image side surface. By setting the object side surface or image side surface of at least one lens among the lenses sequentially arranged from the object side to the image side to be a plane, on the one hand, it is beneficial to the processing of the lens, and on the other hand, since the curvature at the plane is zero, when the position of the lens is slightly offset, it will not have a great impact on the imaging of the optical system, so the sensitivity of the optical system can be effectively reduced, and the assembly yield of the lens can be improved.

[0061] In an exemplary embodiment, the object side surface of the fifth lens is a spherical surface or an aspherical surface, and the image side surface of the fifth lens is a spherical surface or an aspherical surface. By setting the object side surface of the fifth lens to be a spherical surface or an aspherical surface and the image side surface to be a spherical surface or an aspherical surface, that is, both the object side surface and the image side surface of the fifth lens are not planes, it is beneficial to correct the aberration of the optical system and improve the edge resolution of the image formed by the optical system.

[0062] In an exemplary embodiment, the distance from the object side surface of the first lens to the imaging surface of the optical system on the optical axis is L, the effective focal length of the optical system is f, and the optical system satisfies the following relational expression: 1 < L / f < 5. By controlling the distance from the object side surface of the first lens to the imaging surface of the optical system on the optical axis and the effective focal length of the optical system to satisfy the above relationship, the overall length of the optical system can be prevented from being too long, and the effective focal length of the optical system can be prevented from being too long, so it is beneficial to realize the miniaturization and wide-angle of the lens.

[0063] In an exemplary embodiment, the refractive index Nd3 and Abbe number Vd3 of the third lens respectively satisfy Nd3 > 1.9, Vd3 < 30; the refractive index Nd6 and Abbe number Vd6 of the sixth lens respectively satisfy Nd6 > 1.9, Vd6 < 30. Using materials that satisfy the above refractive index relationship and Abbe number relationship to prepare the third lens and the sixth lens is beneficial to correcting the axial chromatic aberration and magnification chromatic aberration of the optical system, and further improving the imaging quality.

[0064] In an exemplary embodiment, the radius of curvature of the image side surface of the fourth lens is R8, the effective focal length of the optical system is f, and the optical system satisfies the following relationship: -2 < R8 / f < -0.5. By controlling the radius of curvature of the image side surface of the fourth lens and the effective focal length of the optical system to satisfy the above relationship, it is beneficial to correct the field curvature and spherical aberration of the optical system.

[0065] In an exemplary embodiment, the combined focal length of the fourth lens, the fifth lens, and the sixth lens is f456, the effective focal length of the optical system is f, and the optical system satisfies the following relationship: f456 / f > 0.5. By controlling the combined focal length of the fourth lens, the fifth lens, and the sixth lens and the effective focal length of the optical system to satisfy the above relationship, it is beneficial to further correct the field curvature of the optical system, and at the same time, it can also increase the optical back focal length of the optical system, so as to facilitate the installation of a filter and a protective glass between the sixth lens and the imaging surface. The optical back focal length is defined as the distance on the optical axis from the image side surface of the last lens of the optical system to the imaging surface. In this embodiment, the last lens is the sixth lens.

[0066] In an exemplary embodiment, the horizontal field of view angle of the optical system is FOV, the chief ray angle of incidence of the optical system is CRA, and the optical system satisfies the following relationship: FOV / CRA > 5. By controlling the horizontal field of view angle of the optical system and the chief ray angle of incidence of the optical system to satisfy the above relationship, it is possible to increase the horizontal field of view angle of the optical system to meet the wide-angle shooting requirements of electronic products such as mobile phones and cameras, and at the same time, it is also possible to reduce the chief ray angle of incidence of the optical system to improve the photosensitive performance of the optical system and improve the imaging effect.

[0067] In an exemplary embodiment, the radius of curvature of the image side surface of the first lens is R2, the effective focal length of the optical system is f, and the optical system satisfies the following relationship: 0.5 < R2 / f < 1.5. By controlling the radius of curvature of the image side surface of the first lens and the effective focal length of the optical system to satisfy the above relationship, it is beneficial to correct the distortion of the optical system and to achieve wide-angleization of the optical system; at the same time, as the radius of curvature of the image side surface of the first lens decreases, the difficulty of lens processing and coating will increase accordingly. Therefore, by controlling the radius of curvature of the image side surface of the first lens within a reasonable range through the above relationship, the difficulty of lens processing and coating can be reduced, the production yield of the lens can be improved, and the production cost can be reduced.

[0068] In an exemplary embodiment, the distance on the optical axis from the image side surface of the third lens to the object side surface of the fourth lens is D34, the effective focal length of the optical system is f, and the optical system satisfies the following relationship: 3 < (D34 / f) * 100 < 6. By controlling the distance on the optical axis from the image side surface of the third lens to the object side surface of the fourth lens and the effective focal length of the optical system to satisfy the above relationship, the overall length of the optical system can be effectively reduced, and miniaturization of the lens can be achieved.

[0069] In an exemplary embodiment, the material of each lens in the optical system is glass. Specifically, the glass can be LAF material glass, LAH material glass, or LASF and TAF material glass. Using glass materials with high refractive index and low dispersion characteristics to prepare lenses can enable the lenses to have better light transmission performance, further ensuring the high-definition imaging effect of the optical system. At the same time, it also broadens the working temperature range of the optical system, enabling it to achieve good imaging effects within the range of -40°C to 85°C, and improving the working stability of the optical system in harsh environments.

[0070] In an exemplary embodiment, the optical system further includes a filter for filtering infrared light and / or a protective glass for protecting the photosensitive element located on the imaging surface, wherein the filter is disposed between the sixth lens and the photosensitive element.

[0071] The optical system according to the above embodiment of the present application can employ multiple lenses, such as the six lenses described above. By reasonably distributing the refractive power, surface shape of each lens, and the spacing between each lens, the F-number of the optical system can be effectively reduced, the light transmission amount of the optical system can be increased, and a subject-prominent, clear, and bright image can be obtained. At the same time, the production cost of the optical system is also reduced, which is conducive to miniaturization. In addition, the lens material in this optical system uses glass, so it has a wide working temperature range, and thus can still work normally in high and low temperature environments, which is conducive to being adapted to devices with harsh working environments such as vehicle-mounted and surveillance lenses. It can be understood that although six lenses are described as an example in the embodiment, the optical system is not limited to including six lenses. If necessary, the optical system can also include other numbers of lenses.

[0072] The following further describes specific embodiments of the optical system applicable to the above embodiment with reference to the accompanying drawings.

[0073] Embodiment 1

[0074] The following refers to Figures 1 to 2C Describe the optical system of Embodiment 1 of the present application.

[0075] Figure 1 Fig. shows a schematic structural diagram of the optical system of Embodiment 1. As Figure 1 shown, the optical system sequentially includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and an imaging surface S17 along the optical axis from the object side to the image side.

[0076] The first lens L1 has a negative refractive power, and its object side surface S1 and image side surface S2 are both spherical surfaces, where the object side surface S1 is a convex surface and the image side surface S2 is a concave surface.

[0077] The second lens L2 has a positive refractive power, and its object side S3 and image side S4 are both spherical surfaces, where the object side S3 is a convex surface and the image side S4 is a convex surface.

[0078] The third lens L3 has a negative refractive power, and its object side S5 and image side S6 are both spherical surfaces, where the object side S5 is a concave surface and the image side S6 is a concave surface.

[0079] The fourth lens L4 has a positive refractive power, and its object side S7 and image side S8 are both spherical surfaces, where the object side S7 is a flat surface and the image side S8 is a convex surface.

[0080] The fifth lens L5 has a positive refractive power, and its object side S9 and image side S10 are both spherical surfaces, where the object side S9 is a convex surface and the image side S10 is a convex surface.

[0081] The sixth lens L6 has a negative refractive power, and its object side S11 and image side S12 are both spherical surfaces, where the object side S11 is a concave surface and the image side S12 is a flat surface.

[0082] An aperture stop STO is also provided between the second lens L2 and the third lens L3 to further improve the imaging quality of the optical system.

[0083] Optionally, the optical system further includes a filter L7 having an object side S13 and an image side S14 and a protective glass L8 having an object side S15 and an image side S16. Light from the object OBJ sequentially passes through the surfaces S1 to S16 and finally forms an image on the imaging surface S17. Optionally, the filter L7 is an infrared filter for filtering infrared light in the external light incident on the optical system to avoid imaging distortion.

[0084] Table 1 shows the surface types, radii of curvature, thicknesses, materials, refractive indices, Abbe numbers of the lenses of the optical system of Example 1, and the effective focal lengths of the lenses. Among them, the units of the radius of curvature, thickness, and the effective focal length of each lens are all millimeters (mm). The reference wavelength is 587.56 nm.

[0085] Table 1

[0086]

[0087] Therefore, from the data in Table 1, it can be seen that in this embodiment, the first lens L1 to the sixth lens L6 all adopt glass spherical lenses, and the optical system in Example 1 satisfies:

[0088] f / D = 1.6, where f is the effective focal length of the optical system and D is the entrance pupil diameter of the optical system;

[0089] L / f = 3.865, where L is the distance on the optical axis from the object side surface S1 of the first lens L1 to the imaging surface S17 of the optical system, and f is the effective focal length of the optical system;

[0090] Nd3 = 1.92, Vd3 = 18.9, Nd6 = 1.92, Vd6 = 18.9, where Nd3 is the refractive index of the third lens L3, Vd3 is the Abbe number of the third lens L3, Nd6 is the refractive index of the sixth lens L6, and Vd6 is the Abbe number of the sixth lens L6.

[0091] R8 / f = -1.11, where R8 is the radius of curvature of the image side surface S8 of the fourth lens L4, and f is the effective focal length of the optical system;

[0092] f456 / f = 0.77, where f456 is the combined focal length of the fourth lens L4, the fifth lens L5, and the sixth lens L6, and f is the effective focal length of the optical system;

[0093] FOV / CRA = 5.72, where FOV is the horizontal field of view angle of the optical system, and CRA is the chief ray angle of incidence of the optical system;

[0094] R2 / f = 0.649, where R2 is the radius of curvature of the image side surface S2 of the first lens L1, and f is the effective focal length of the optical system;

[0095] (D34 / f)*100 = 5.2, where D34 is the distance on the optical axis from the image side surface S6 of the third lens L3 to the object side surface S7 of the fourth lens L4, and f is the effective focal length of the optical system.

[0096] Figure 2A The longitudinal spherical aberration curve of the optical system of Example 1 is shown, which respectively represents the deviation of the converging points of the light rays with wavelengths of 435.83 nm, 546.07 nm, 587.56 nm, and 656.27 nm after passing through the optical system; Figure 2B The astigmatism curve of the optical system of Example 1 is shown, which represents the meridional image plane curvature and the sagittal image plane curvature; Figure 2C The distortion curve of the optical system of Example 1 is shown, which represents the distortion rate in different viewing angle cases. According to Figures 2A to 2C It can be seen that the optical system given in Example 1 can achieve good imaging quality.

[0097] Example 2

[0098] The following refers to Figures 3 to 4C Describe the optical system of Embodiment 2 of the present application. In this embodiment, for the sake of simplicity, some descriptions similar to those in Embodiment 1 will be omitted. Figure 3 The structural schematic diagram of the optical system of Embodiment 2 of the present application is shown.

[0099] As Figure 3 shown, the optical system sequentially includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and an imaging surface S17 along the optical axis from the object side to the image side.

[0100] The first lens L1 has a negative refractive power, and its object surface S1 and image surface S2 are both spherical surfaces, where the object surface S1 is a convex surface and the image surface S2 is a concave surface.

[0101] The second lens L2 has a positive refractive power, and its object surface S3 and image surface S4 are both spherical surfaces, where the object surface S3 is a convex surface and the image surface S4 is a convex surface.

[0102] The third lens L3 has a negative refractive power, and its object surface S5 and image surface S6 are both spherical surfaces, where the object surface S5 is a concave surface and the image surface S6 is a concave surface.

[0103] The fourth lens L4 has a positive refractive power, and its object surface S7 and image surface S8 are both spherical surfaces, where the object surface S7 is a flat surface and the image surface S8 is a convex surface.

[0104] The fifth lens L5 has a positive refractive power, and its object surface S9 and image surface S10 are both aspherical surfaces, where the object surface S9 is a convex surface and the image surface S10 is a convex surface.

[0105] The sixth lens L6 has a negative refractive power, and its object surface S11 and image surface S12 are both spherical surfaces, where the object surface S11 is a concave surface and the image surface S12 is a flat surface.

[0106] An aperture stop STO is further provided between the second lens L2 and the third lens L3 to further improve the imaging quality of the optical system.

[0107] Optionally, the optical system further includes a filter L7 having an object surface S13 and an image surface S14 and a protective glass L8 having an object surface S15 and an image surface S16. Light from the object OBJ sequentially passes through the surfaces S1 to S16 and finally forms an image on the imaging surface S17. Optionally, the filter L7 is an infrared filter.

[0108] Table 2 shows the surface types, radii of curvature, thicknesses, materials, refractive indices, Abbe numbers, and effective focal lengths of the lenses of the optical system of Example 2, where the units of the radii of curvature, thicknesses, and effective focal lengths of the lenses are all millimeters (mm). The reference wavelength is 587.56 nm.

[0109] Table 2

[0110]

[0111]

[0112] As can be seen from Table 2, in this embodiment, both the object side surface S9 and the image side surface S10 of the fifth lens L5 are aspherical surfaces, and the aspherical surface profiles x are defined by the following formula:

[0113]

[0114] Where x is the distance sagitta from the vertex of the aspherical surface when the aspherical surface is at a position with a height of h along the optical axis; c is the paraxial curvature of the aspherical surface, c = 1 / R (that is, the paraxial curvature c is the reciprocal of the radius of curvature R in Table 2); k is the conic coefficient; Ai is the i-th order coefficient of the aspherical surface. Table 3 below gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for the aspherical mirror surfaces S9 and S10 in Embodiment 2.

[0115] Table 3

[0116]

[0117] Table 4 shows the numerical values of the relevant parameters of the optical system of Embodiment 2.

[0118] Table 4

[0119] f (mm) 5.46 Vd6 18.9 f / D 1.6 R8 / f -1.1 FOV (degrees) 64.52 f456 / f 0.77 L / f 3.839 FOV / CRA 5.55 Nd3 1.92 R2 / f 0.642 Vd3 18.9 D34 / f 4.56 Nd6 1.92

[0120] Figure 4A shows the longitudinal spherical aberration curve of the optical system of Embodiment 2, which respectively represents the deviation of the focusing points of light rays with different wavelengths after passing through the optical system; Figure 4B shows the astigmatism curve of the optical system of Embodiment 2, which represents the meridional image plane curvature and the sagittal image plane curvature; Figure 4C shows the distortion curve of the optical system of Embodiment 2, which represents the distortion rate under different viewing angles. According to Figures 4A to 4C it can be seen that the optical system given in Embodiment 2 can achieve good imaging quality.

[0121] Embodiment 3

[0122] The following refers to Figures 5 to 6C to describe the optical system of Embodiment 3 of the present application. In this embodiment, for the sake of simplicity, some descriptions similar to those in Embodiment 1 will be omitted. Figure 5 shows the structural schematic diagram of the optical system of Embodiment 3 of the present application.

[0123] As Figure 5 shown, the optical system sequentially includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and an imaging surface S17 along the optical axis from the object side to the image side.

[0124] The first lens L1 has a negative refractive power. Both its object side S1 and image side S2 are spherical surfaces, where the object side S1 is convex and the image side S2 is concave.

[0125] The second lens L2 has a positive refractive power. Both its object side S3 and image side S4 are spherical surfaces, where the object side S3 is convex and the image side S4 is convex.

[0126] The third lens L3 has a negative refractive power. Both its object side S5 and image side S6 are spherical surfaces, where the object side S5 is concave and the image side S6 is concave.

[0127] The fourth lens L4 has a positive refractive power. Both its object side S7 and image side S8 are spherical surfaces, where the object side S7 is planar and the image side S8 is convex.

[0128] The fifth lens L5 has a positive refractive power. Both its object side S9 and image side S10 are aspherical surfaces, where the object side S9 is convex and the image side S10 is convex.

[0129] The sixth lens L6 has a negative refractive power. Both its object side S11 and image side S12 are spherical surfaces, where the object side S11 is concave and the image side S12 is planar.

[0130] An aperture stop STO is also disposed between the second lens L2 and the third lens L3 to further improve the imaging quality of the optical system.

[0131] Optionally, the optical system further includes a filter L7 having an object side S13 and an image side S14, and a protective glass L8 having an object side S15 and an image side S16. Light from the object OBJ sequentially passes through the surfaces S1 to S16 and finally forms an image on the imaging surface S17. Optionally, the filter L7 is an infrared filter.

[0132] Table 5 shows the surface types, radii of curvature, thicknesses, materials, refractive indices, Abbe numbers, and effective focal lengths of the lenses of the optical system in Embodiment 3. Among them, the units of the radius of curvature, thickness, and effective focal length of each lens are all millimeters (mm); Table 6 shows the high-order term coefficients of the object side S9 and the image side S10 of the fifth lens L5 that can be used in Embodiment 3, where the aspherical surface type can be defined by the formula (1) given in Embodiment 2; Table 7 shows the numerical values of the relevant parameters of the optical system given in Embodiment 3. The reference wavelength is 587.56 nm.

[0133] Table 5

[0134]

[0135]

[0136] Table 6

[0137]

[0138] Table 7

[0139]

[0140]

[0141] Figure 6A shows the longitudinal spherical aberration curve of the optical system of Embodiment 3, which respectively represents the deviation of the converging points of light rays with different wavelengths after passing through the optical system; Figure 6B shows the astigmatism curve of the optical system of Embodiment 3, which represents the meridional image plane curvature and the sagittal image plane curvature; Figure 6C shows the distortion curve of the optical system of Embodiment 3, which represents the distortion rate in different viewing angle cases. According to Figures 6A to 6C it can be known that the optical system given in Embodiment 3 can achieve good imaging quality.

[0142] This application also provides an image pickup device, including the optical system as described above and a photosensitive element. The photosensitive element is disposed on the image side of the optical system to receive the light carrying image information formed by the above optical system.

[0143] Specifically, the photosensitive element can adopt a complementary metal oxide semiconductor (CMOS, Complementary Metal Oxide Semiconductor) image sensor or a charge coupled device (CCD, Charge - coupled Device) image sensor.

[0144] The above - mentioned image pickup device can obtain a clear and bright image by using an optical system with a small F - number. At the same time, the total length of the image pickup device is small and the production yield is high, which is beneficial to realizing miniaturization and reducing production costs.

[0145] This application also provides an electronic device, including a housing and the image pickup device as described above. The image pickup device is installed on the housing to acquire images.

[0146] Specifically, the image pickup device is disposed inside the housing and exposed from the housing to acquire images. The housing can provide protection such as dust - proof, waterproof and anti - fall for the image pickup device. A hole corresponding to the image pickup device is opened on the housing to enable light to penetrate into or out of the housing through the hole.

[0147] The above - mentioned electronic device can capture bright and clear images by using the image pickup device as described above, meeting the shooting requirements of electronic devices such as vehicle - mounted cameras and surveillance cameras.

[0148] The technical features of the above-described embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope described in this specification.

[0149] The above-described embodiments merely represent several implementation manners of the present invention, and the description thereof is relatively specific and detailed. However, it should not be construed as a limitation on the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention patent shall be subject to the appended claims.

Claims

1. An optical system sequentially includes, from the object side to the image side along the optical axis: A first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens. Among the lenses in the optical system, only six lenses have optical power. It is characterized in that, The first lens has a negative refractive power, its object side is convex, and its image side is concave; The second lens has a positive refractive power, its object side is convex, and its image side is convex; The third lens has a negative refractive power, its object side is concave, and its image side is concave; The fourth lens has a positive refractive power; The fifth lens has a positive refractive power; The sixth lens has a negative refractive power, and its object side is concave; An aperture stop is provided between the second lens and the third lens; The optical system satisfies the following relational expressions: f / D ≤ 1.6; Wherein, f is the effective focal length of the optical system, and D is the entrance pupil diameter of the optical system; 5 < FOV / CRA ≤ 5.72; Wherein, FOV is the horizontal field of view angle of the optical system, and CRA is the chief ray incident angle of the optical system.

2. The optical system according to claim 1, wherein Among the lenses arranged in sequence from the object side to the image side along the optical axis, at least one lens has a flat object side or image side.

3. The optical system according to claim 1, characterized in that, The object side of the fifth lens is spherical or aspherical, and the image side of the fifth lens is spherical or aspherical.

4. The optical system according to claim 1, characterized in that The optical system satisfies the following relational expressions: 1 < L / f < 5; Wherein, L is the distance on the optical axis from the object side of the first lens to the imaging surface of the optical system, and f is the effective focal length of the optical system.

5. The optical system according to claim 1, characterized in that, The refractive index Nd3 and Abbe number Vd3 of the third lens respectively satisfy Nd3 > 1.9, Vd3 < 30; The refractive index Nd6 and Abbe number Vd6 of the sixth lens respectively satisfy Nd6 > 1.9, Vd6 < 30.

6. The optical system according to claim 1, characterized in that, When the optical system satisfies the following relationship: -2 < R8 / f < -0.5; Wherein, R8 is the radius of curvature of the image side of the fourth lens, and f is the effective focal length of the optical system.

7. The optical system according to claim 1, characterized in that The optical system satisfies the following relational expressions: f456 / f > 0.5; Wherein, f456 is the combined focal length of the fourth lens, the fifth lens, and the sixth lens, and f is the effective focal length of the optical system.

8. The optical system according to claim 1, characterized in that The optical system satisfies the following relational expressions: f / D = 1.6; The fourth lens has a positive refractive power, its object side is flat, and its image side is convex; The fifth lens has a positive refractive power, its object side is convex, and its image side is convex; The sixth lens has a negative refractive power, and its image side is flat.

9. The optical system according to claim 1, wherein The optical system satisfies the following relational expressions: 0.5 < R2 / f < 1.5; Wherein, R2 is the radius of curvature of the image side of the first lens, and f is the effective focal length of the optical system.

10. The optical system according to claim 1, characterized in that, The optical system satisfies the following relational expressions: 3 < (D34 / f) * 100 < 6; Wherein, D34 is the distance on the optical axis from the image side of the third lens to the object side of the fourth lens, and f is the effective focal length of the optical system.

11. An imaging device, characterized in that, Comprising: The optical system according to any one of claims 1-10; And, An image sensor, which is disposed on the image side of the optical system to receive light carrying image information formed by the optical system.

12. An electronic device, characterized in that, Comprising: A housing; And An imaging device as claimed in claim 11, which is mounted on the housing for acquiring an image.

Images