Optical system, camera module and electronic device

Abstract

The present application discloses an optical system, an imaging module and an electronic device. The optical system includes a first lens, a second lens, a third lens and a fourth lens arranged in sequence; the first lens and the second lens form a first lens group, the third lens and the fourth lens form a second lens group, the first lens group is fixed relative to the imaging plane of the optical system, and the second lens group is movable along the optical axis direction; the optical system satisfies the relational expressions: 24deg<FOV<30deg, 1.95<FNO<2.7; FOV is the maximum field of view of the optical system, and FNO is the f-number of the optical system. The optical system, the imaging module and the electronic device disclosed in the present application can effectively shorten the focusing stroke on the basis of taking into account the miniaturization design, so as to reduce the overall thickness of the optical system, and enable the optical system to adapt to the thin and light design of smart terminals such as mobile phones and tablet computers.

Description

Technical Field

[0001] This application relates to the field of optical imaging technology, and in particular to an optical system, camera module and electronic device. Background Technology

[0002] As the miniaturization requirements of smart devices such as mobile phones and tablets increase, new challenges have arisen for the design of optical systems incorporated into these devices. In most related technologies, optical systems achieve optical zoom by moving multiple internal lens groups in tandem. However, this method requires significant space for movement and a large focusing distance, resulting in a relatively large overall thickness of the optical system. This leads to a considerable protrusion of the optical system onto smart devices like mobile phones and tablets, hindering the pursuit of a thinner and lighter design. Summary of the Invention

[0003] This application discloses an optical system, camera module, and electronic device that can effectively shorten the focusing stroke while maintaining a miniaturized design, thereby reducing the overall thickness of the optical system and enabling it to adapt to the thin and light design of smart terminals such as mobile phones and tablets.

[0004] To achieve the above objective, firstly, the optical system comprises four lenses with refractive power, arranged sequentially along the object-side to image-side direction of the optical axis:

[0005] A first lens group, comprising a first lens and a second lens sequentially arranged along the object-side to the image-side direction of the optical axis, wherein the first lens has positive refractive power, the object-side surface of the first lens is convex near the optical axis, and the image-side surface of the first lens is concave near the optical axis; the second lens has negative refractive power, the object-side surface of the second lens is concave near the optical axis, and the image-side surface of the second lens is convex near the optical axis; and

[0006] The second lens group includes a third lens and a fourth lens arranged sequentially along the object-side to image-side direction of the optical axis. The third lens has negative refractive power, and both the object-side and image-side surfaces of the third lens are concave near the optical axis. The fourth lens has positive refractive power, and both the object-side and image-side surfaces of the fourth lens are convex near the optical axis.

[0007] Wherein, the first mirror group is fixed relative to the imaging surface of the optical system, and the other mirror group of the second mirror group is movable along the optical axis;

[0008] The optical system satisfies the following relationship: 24deg <FOV<30deg、1.95<FNO<2.7;

[0009] FOV is the maximum field of view of the optical system, and FNO is the aperture number of the optical system.

[0010] Secondly, this application discloses a camera module, which includes an image sensor and an optical system as described in the first aspect above, wherein the image sensor is disposed on the image side of the optical system. A camera module with the aforementioned optical system can effectively shorten the focusing distance, thereby reducing the overall thickness of the camera module and enabling it to adapt to the thinner and lighter design of smart terminals such as mobile phones and tablets.

[0011] Thirdly, this application discloses an electronic device comprising a housing and a camera module as described in the second aspect above, the camera module being disposed within the housing. An electronic device having the aforementioned camera module can also effectively achieve a thin and light design.

[0012] Compared with the prior art, the beneficial effects of this application are as follows:

[0013] In the optical system provided in this application, in order to achieve miniaturization and effectively shorten the focusing stroke, thereby reducing the overall thickness of the optical system, four lenses are divided into a first lens group and a second lens group. One of the first and second lens groups is fixed relative to the imaging surface of the optical system, while the other is movable along the optical axis. This enables the optical system to have continuous internal focusing functionality. By utilizing only one lens group for movement, the load on the motor of the optical system can be further reduced, achieving a fast internal focusing effect with a lower-power motor. Moreover, this movement method results in a shorter focusing stroke, effectively reducing the thickness of the optical system.

[0014] On this basis, the present application further designs the refractive power and surface profile of the four lenses. That is, by using four lenses with refractive power, the present application can disperse the light refraction pressure to each lens, so as to reduce the light refraction task load of a single lens, and avoid excessively curved lenses that increase tolerance sensitivity. Specifically, the first lens has positive refractive power, and with the design that its object side and image side are respectively convex and concave at the paraxial region, it can facilitate better entry of light into the first lens; the second lens has negative refractive power, with its object side being concave at the paraxial region and its image side being convex at the paraxial region, which can help correct the aberration generated by the first lens and improve the imaging effect of the optical system. The third lens has negative refractive power, and both its object side and image side are concave at the paraxial region, which can help reduce the incident angle of light entering the optical system, so that as much light as possible enters the optical system. The fourth lens has positive refractive power, and its object side and image side are respectively convex and concave at the paraxial region, which is beneficial for correcting spherical aberration, coma and distortion generated by the first lens group, and can mitigate the exit angle of light, facilitating large-range light to enter the image plane and further improving the imaging quality of the optical system. Moreover, among the first to fourth lenses, the design of a convex-concave lens matched with a biconcave lens is adopted, so that the thickness of each lens is smaller, which further facilitates the control of the overall thickness of the optical system, and thus is beneficial to the miniaturization design of the optical system.

[0015] In addition, the optical system satisfies the relational expressions: 24deg<FOV<30deg, 1.95<FNO<2.7, which enables the optical system to have an appropriate field of view to match telescopic applications, and at the same time, can achieve a balance between illumination and depth of field, and increase the light intake to improve image quality. Brief Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following will briefly introduce the drawings required in the embodiments. Obviously, the drawings in the following description are only some embodiments of the present application, and for those of ordinary skill in the art, other drawings can also be obtained based on these drawings without any creative effort.

[0017] Figure 1A is a schematic structural diagram of the optical system disclosed in the first embodiment of the present application in a far-focus state;

[0018] Figure 1B is an astigmatism curve diagram (mm) and a distortion curve diagram (%) of the optical system disclosed in the first embodiment of the present application in a far-focus state;

[0019] Figure 1C is a lateral chromatic aberration curve diagram of the optical system disclosed in the first embodiment of the present application in a far-focus state;

[0020] Figure 2A This is a schematic diagram of the optical system disclosed in the first embodiment of this application in a near-focus state;

[0021] Figure 2B These are the astigmatism curve (mm) and distortion curve (%) of the optical system disclosed in the first embodiment of this application in a near-focus state;

[0022] Figure 2C This is a chromatic aberration curve of the optical system disclosed in the first embodiment of this application in a near-focus state;

[0023] Figure 3A This is a schematic diagram of the optical system disclosed in the second embodiment of this application in the telephoto state;

[0024] Figure 3B These are the astigmatism curve (mm) and distortion curve (%) of the optical system disclosed in the second embodiment of this application in the telephoto state;

[0025] Figure 3C This is a diagram of the chromatic aberration curve of the optical system disclosed in the second embodiment of this application in the telephoto state;

[0026] Figure 4A This is a schematic diagram of the optical system disclosed in the second embodiment of this application in a near-focus state;

[0027] Figure 4B These are the astigmatism curve (mm) and distortion curve (%) of the optical system disclosed in the second embodiment of this application in a near-focus state;

[0028] Figure 4C This is a chromatic aberration curve of the optical system disclosed in the second embodiment of this application in a near-focus state;

[0029] Figure 5A This is a schematic diagram of the optical system disclosed in the third embodiment of this application in the telephoto state;

[0030] Figure 5B These are the astigmatism curve (mm) and distortion curve (%) of the optical system disclosed in the third embodiment of this application in the telephoto state;

[0031] Figure 5C This is a diagram of the chromatic aberration curve of the optical system disclosed in the third embodiment of this application in the telephoto state;

[0032] Figure 6A This is a schematic diagram of the optical system disclosed in the third embodiment of this application in a near-focal state;

[0033] Figure 6B These are the astigmatism curve (mm) and distortion curve (%) of the optical system disclosed in the third embodiment of this application in a near-focus state;

[0034] Figure 6C This is a chromatic aberration curve of the optical system disclosed in the first embodiment of this application in a near-focus state;

[0035] Figure 7A This is a schematic diagram of the optical system disclosed in the fourth embodiment of this application in the telephoto state;

[0036] Figure 7B These are the astigmatism curve (mm) and distortion curve (%) of the optical system disclosed in the fourth embodiment of this application in the telephoto state;

[0037] Figure 7C This is a diagram of the vertical chromatic aberration curve of the optical system disclosed in the fourth embodiment of this application in the telephoto state;

[0038] Figure 8A This is a schematic diagram of the optical system disclosed in the fourth embodiment of this application in a near-focus state;

[0039] Figure 8B These are the astigmatism curve (mm) and distortion curve (%) of the optical system disclosed in the fourth embodiment of this application in a near-focus state;

[0040] Figure 8C This is a chromatic aberration curve of the optical system disclosed in the fourth embodiment of this application in a near-focus state;

[0041] Figure 9A This is a schematic diagram of the optical system disclosed in the fifth embodiment of this application in the telephoto state;

[0042] Figure 9B These are the astigmatism curve (mm) and distortion curve (%) of the optical system disclosed in the fifth embodiment of this application in the telephoto state;

[0043] Figure 9C This is a diagram of the chromatic aberration curve of the optical system disclosed in the fifth embodiment of this application in the telephoto state;

[0044] Figure 10A This is a schematic diagram of the optical system disclosed in the fifth embodiment of this application in a near-focus state;

[0045] Figure 10B These are the astigmatism curve (mm) and distortion curve (%) of the optical system disclosed in the fifth embodiment of this application in a near-focus state;

[0046] Figure 10C This is a chromatic aberration curve of the optical system disclosed in the fifth embodiment of this application in a near-focus state;

[0047] Figure 11 This is a schematic diagram of the camera module disclosed in this application;

[0048] Figure 12 This is a schematic diagram of the structure of the electronic device disclosed in this application. Detailed Implementation

[0049] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0050] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, elements, or components (which may be the same or different in specific type and construction), and are not intended to indicate or imply the relative importance or quantity of the indicated devices, elements, or components. Unless otherwise stated, "a plurality of" means two or more.

[0051] The technical solution of this application will be further described below with reference to the embodiments and accompanying drawings.

[0052] Please see Figure 1A and Figure 2A According to a first aspect of this application, an optical system 100 is disclosed. The optical system 100 includes a first lens group G1 and a second lens group G2 arranged sequentially along the optical axis from the object side to the image side. The first lens group G1 includes a first lens L1 and a second lens L2 arranged sequentially from the object side to the image side along the optical axis. The second lens group G2 includes a third lens L3 and a fourth lens L4 arranged sequentially from the object side to the image side along the optical axis. The first lens group G1 is fixed relative to the imaging plane IMG of the optical system 100, while the second lens group G2 is movable along the optical axis, thereby enabling the optical system 100 to have continuous internal focusing functionality. Furthermore, by utilizing only one lens group for movement, the required thrust is smaller, reducing the difficulty of focusing design and facilitating mass production.

[0053] Understandably, by moving the second lens group G2, the optical system 100 can switch between near-focus and telephoto states. Taking the first lens group G1 as a fixed example, when the optical system is in near-focus state, the second lens group G2 is positioned closer to the first lens group G1 along the optical axis. When the optical system 100 is in telephoto state, the second lens group G2 is positioned further away from the first lens group G1 along the optical axis; that is, the second lens group G2 moves along the direction close to the imaging surface IMG of the optical system, moving away from the first lens group G1 and closer to the imaging surface IMG of the optical system.

[0054] Optionally, the first lens L1 has positive refractive power, which helps to compress the length of the optical axis of the lens group of the optical system 100 near the object side, thereby reducing the thickness of the entire optical system 100 in the optical axis direction near the object side. The object-side surface S1 of the first lens L1 is convex near the optical axis, thereby allowing adjustment of the surface shape of the object-side surface of the first lens L1, thus enhancing the optical path control capability of the light-incident surface of the first lens L1. The image-side surface S2 of the first lens L1 is concave near the optical axis, thereby allowing adjustment of the surface shape of the image-side surface S2 of the first lens L1, which helps to correct aberrations such as astigmatism.

[0055] Optionally, the second lens L2 has a negative refractive power, which can balance the aberrations generated by the lens assembly in the compressed optical system. The object-side surface S3 of the second lens L2 is convex near the optical axis, and the image-side surface S4 of the second lens L2 is concave near the optical axis, which can adjust the direction of light propagation and help balance the volume configuration of the lens assembly at the object-side end of the optical system.

[0056] Optionally, the third lens L3 has negative refractive power, thus enabling it to work in conjunction with the first lens group G1 to reduce coma in the peripheral field of view. The object-side surface S5 of the third lens L3 is concave near the optical axis, and the image-side surface S6 is also concave near the optical axis. This allows for adjustment of the surface of the third lens L3, thereby facilitating the adjustment of the light-tracing direction and helping to increase the imaging area. Simultaneously, it can also delay the angle of light rays entering the optical system 100 from the first lens group G1, allowing the light rays to enter the second lens group G2 more smoothly.

[0057] Optionally, the fourth lens L4 has positive refractive power, thereby balancing the aberrations generated by the optical system. The object-side surface S7 of the fourth lens L4 is convex near the optical axis, and the image-side surface S8 of the fourth lens L4 is concave near the optical axis. This helps to correct spherical aberration, coma, and distortion generated by the front lens group, while also reducing the exit angle of light rays, which is beneficial for a wider range of light rays to enter the imaging plane IMG of the optical system 100.

[0058] In some embodiments, the optical system 100 can be applied to electronic devices such as smartphones and tablets. The first lens L1, second lens L2, third lens L3, and fourth lens L4 can be made of plastic or glass. Using plastic lenses allows for a lighter optical system 100 while also making it easier to process complex lens shapes. Using glass lenses provides good optical performance and reduces the temperature sensitivity of the optical system. Of course, in other embodiments, the optical system 100 can also be applied to electronic devices such as in-vehicle devices and dashcams, or to automobiles as a camera mounted on the vehicle body.

[0059] In some embodiments, the optical system 100 may further include a reflector LP, which may be disposed between the image-side surface S8 of the fourth lens L4 and the imaging surface IMG of the optical system 100. Thus, the reflector LP allows the optical system 100 to have different optical path orientations, making the lens space configuration more flexible, helping to reduce structural limitations and achieve miniaturization of the optical system.

[0060] Optionally, the reflector LP can be one or more, and the reflector LP may include a prism or a mirror. Taking the reflector LP as a prism as an example, the prism can bend the light path at least twice, thereby extending the light path in the optical system 100, thus achieving a longer light path in a limited lens space, meeting telephoto requirements, and thus adapting to miniaturized smart terminals.

[0061] Optionally, Figure 2A The optical path of the optical system 100 in the telephoto state is shown in the figure. Figure 2B The diagram shows the optical path of the optical system 100 in a near-focus state. The near-focus state refers to the state when the object distance of the optical system is 300 mm, and the far-focus state refers to the state when the object distance of the optical system 100 is at infinity.

[0062] The near-focus state refers to the state of the optical system when the object distance is 300mm, and the far-focus state refers to the state of the optical system when the object distance is infinity.

[0063] It is understood that the above example with an object distance of 300mm is for illustrative purposes; that is, the image quality is optimal at an object distance of 300mm. Of course, imaging is also possible with an object distance less than 300mm; that is, in some other embodiments, a scheme with an object distance less than 300mm can also be used. Specific adjustments can be made according to actual needs, and no specific limitations are made here.

[0064] like Figure 1A , Figure 2AAs shown, the optical system 100 includes a first mirror group G1, a second mirror group G2, a reflector LP, and an imaging surface IMG. The reflector LP can be a prism, and it includes a first surface LP1, a first reflecting surface RF1, and a second reflecting surface RF2. The first reflecting surface RF1 and the second reflecting surface RF2 intersect, with the first reflecting surface RF1 connected to one side of the first surface LP1 and the second reflecting surface RF2 connected to the other side of the first surface LP1. The first mirror group, the second mirror group, and the imaging surface IMG of the optical system are located on the same side relative to the first surface LP1. Imaging light sequentially passes through the first mirror group G1 and the second mirror group G2, is transmitted through the first surface LP1 to the reflector, is reflected by the first reflecting surface RF1 to the first surface, is reflected from the first surface to the second reflecting surface RF2, is reflected again by the second reflecting surface RF2 to the first surface LP1, and finally enters the imaging surface IMG of the optical system. Specifically, taking a prism as an example, the imaging light sequentially passes through the first mirror group G1 and the second mirror group G2, and is transmitted through the first surface LP1 into the prism. It is then reflected by the first reflecting surface RF1 back to the first surface LP1, reflected by the first surface LP1 to the second reflecting surface RF2, reflected again by the second reflecting surface RF2 back to the first surface LP1, and transmitted through the first surface LP1 to the outside of the prism, finally converging on the imaging surface IMG of the optical system 100. It can be seen that by setting this reflector LP, the light path can be deflected three times. Therefore, compared to a linear light path, this method of deflecting the light path can effectively control the lengths of the first and second mirror groups in the optical axis direction while achieving a telephoto lens, thus facilitating the miniaturization design of the optical system.

[0065] Of course, as another embodiment, the cross-section of the reflector can be trapezoidal. In this case, the reflector may also include a second surface (not shown), which may be parallel to the first surface. The first reflecting surface is connected between the first and second surfaces, and the second reflecting surface is also connected between the first and second surfaces. Using a trapezoidal reflector, since no imaging light passes through the intersection of the first and second reflecting surfaces, i.e., the optical path is not affected, a second surface is provided at the intersection of the first and second reflecting surfaces. On the one hand, compared to a sharp-cornered design, a planar design is easier to manufacture; on the other hand, since this is a planar design, the thickness of the reflector in the optical axis direction of the first mirror group G1 and the second mirror group G2 can be shortened, thereby facilitating the miniaturization design of the optical system 100.

[0066] It is understood that the first surface LP1 includes an incident light region LP10 and an exit light region LP12, which can be coplanar. Imaging light can enter the reflector from the incident light region and finally exit through the exit light region to the imaging surface of the optical system. Of course, it is understood that, as another example, the incident light region LP10 and the exit light region LP12 can also be non-coplanar, for example, they can be arranged in parallel, and this embodiment does not specifically limit this.

[0067] Please refer to it again. Figure 1A , Figure 2A Optionally, taking the reflector LP as a prism, and the prism causing the light path to bend three times as an example, in this prism, a first included angle α can be formed between the first surface LP1 and the first reflecting surface RF1, and a second included angle β can be formed between the second reflecting surface RF2 and the first surface LP1. The angles of the first included angle α and the second included angle β can both be in the range of 25°-35°. That is, the angle range of the first included angle α can be 25°-35°, and the angle range of the second included angle β can also be 25°-35°. However, it should be noted that the angles of the first included angle α and the second included angle β can be equal or unequal. For example, the angle of the first included angle α can be 30°, and the angle of the second included angle β can be 25°, 28°, or 30°.

[0068] For example, the first included angle α may be further in the range of 28°-35°, or 25°-30°, etc. The second included angle β may be further in the range of 27°-35° or 25°-30°, etc.

[0069] In some embodiments, the thickness L of the reflector LP is approximately between 3.6mm and 3.75mm. For example, the thickness L of the reflector LP can be 3.6mm, 3.61mm, 3.65mm, 3.7mm, 3.75mm, etc. The thickness L of the reflector LP refers to the distance from the first surface LP1 to the intersection of the first reflecting surface RF1 and the second reflecting surface RF2. Of course, when the cross-section of the reflector is trapezoidal, that is, when the reflector also includes a second surface, the thickness L of the reflector LP refers to the distance between the first surface LP1 and the second surface.

[0070] In some embodiments, the optical system 100 further includes an aperture stop STO, which can be an aperture stop and / or a field stop, and can be disposed between the object surface S1 of the first lens L1 and the object surface of the optical system. It is understood that in other embodiments, the aperture stop STO can also be disposed between two other lenses; for example, the aperture stop STO can also be disposed between the first lens L1 and the second lens L2. The specific arrangement can be adjusted according to actual conditions, and this embodiment does not impose specific limitations.

[0071] In some embodiments, the optical system 100 further comprises an IR filter, which is disposed on the second lens group and located between the reflecting element RF and the imaging plane IMG of the optical system 100. Optionally, the IR filter may be an infrared cut-off filter. The use of the infrared cut-off filter can filter out infrared light, improve imaging quality, and make the imaging more consistent with the visual experience of the human eye. It is understandable that the IR filter can be made of coated optical glass, colored glass, or other materials, which can be selected according to actual needs, and no specific limitation is made in this embodiment.

[0072] In some embodiments, the optical system 100 satisfies the following relational expression: 24deg<FOV<30deg; where FOV is the maximum field of view angle of the optical system 100 in the telefocus state. When the optical system 100 satisfies this relational expression, the optical system 100 can have an appropriate viewing angle to cooperate with telescopic applications.

[0073] In some embodiments, the optical system satisfies the following relational expression: <FOVi / FOVm<1.1, where FOVm is the maximum field of view angle of the optical system 100 in the near-focus state, and FOVi is the maximum field of view angle of the optical system 100 in the telefocus state. When this relational expression is satisfied, the difference between the maximum field of view angles of the optical system 100 in the near-focus state and the telefocus state is small, so that the optical system 100 can always maintain the telescopic function.

[0074] In some embodiments, the optical system 100 satisfies the relational expression: 1.95<FNO<2.7. Where FNO is the f-number of the optical system in the telefocus state. In this way, the optical system 100 can have the characteristic of a large aperture, that is, it can achieve a balance between illuminance and depth of field, and increase the light intake to improve image quality.

[0075] In some embodiments, the optical system 100 satisfies the relational expression: 1<FNOm / FNOi<1.1, where FNOm is the f-number of the optical system in the near-focus state, and FNOi is the f-number of the optical system 100 in the telefocus state. When this relational expression is satisfied, the optical system 100 can always have the large aperture characteristic.

[0076] In some embodiments, the optical system 100 satisfies the following relational expression: 1.9<fi / f1<2.3, where f1 is the focal length of the first lens L1, and fi is the focal length of the optical system 100 in the afocal state. By controlling the ratio of the focal length of the optical system 100 in the afocal state to the focal length of the first lens L1, a reasonable refractive power distribution can be obtained for the first lens L1, which helps to reduce the total spherical aberration, chromatic aberration and distortion of the first lens group to a reasonable level, lowers the design difficulty of the subsequent lenses, improves the overall resolving power of the optical system 100, and enhances the peripheral aberration correction of the optical system 100. In addition, it is beneficial to the size reduction of the first lens group, thus contributing to the formation of the optical system 100 with a small size.

[0077] In some embodiments, the optical system 100 satisfies the following relational expression: -30<f2 / fi<-2, where f2 is the focal length of the second lens L2. By controlling the ratio of the focal length of the second lens L2 to the focal length of the optical system 100 in the afocal state, the second lens L2 can have a reasonable refractive power, which helps to reduce the total spherical aberration, chromatic aberration and distortion of the first lens group G1 to a reasonable level, lowers the design difficulty of the subsequent lenses, improves the overall resolving power of the optical system 100, and enhances the peripheral aberration correction of the optical system 100. In addition, it is beneficial to the size reduction of the first lens group G1, thus contributing to the formation of the optical system 100 with a small size.

[0078] In some embodiments, the optical system 100 satisfies the following relational expression: -3.1<fi / f3<-2.2, where f3 is the focal length of the third lens L3. By controlling the ratio of the focal length of the optical system 100 in the afocal state to the focal length of the third lens L3, the third lens L3 can have a reasonable refractive power, which helps to reduce the total spherical aberration, chromatic aberration and distortion of the first lens group to a reasonable level, lowers the design difficulty of the subsequent lenses, improves the overall resolving power of the optical system 100, and enhances the peripheral aberration correction of the optical system 100. In addition, it is beneficial to the size reduction of the first lens group, thus contributing to the formation of the optical system 100 with a small size.

[0079] In some embodiments, the optical system 100 satisfies the following relational expression: 0.55<f4 / fi<1.1, where f4 is the focal length of the fourth lens L4. By controlling the ratio of the focal length of the fourth lens L4 to the focal length of the optical system 100 in the afocal state, the fourth lens L4 can have a reasonable refractive power, which helps to reduce the total spherical aberration, chromatic aberration and distortion of the second lens group to a reasonable level, lowers the design difficulty of the subsequent lenses, improves the overall resolving power of the optical system 100, and enhances the peripheral aberration correction of the optical system 100. In addition, it is beneficial to the size reduction of the second lens group, thus contributing to the formation of the optical system 100 with a small size.

[0080] In some embodiments, the optical system 100 satisfies the relational expression: 1<fi / fm<1.1, where fm is the focal length of the optical system 100 in a near-focus state. When the optical system satisfies this relational expression, the optical system 100 can have an inner focusing effect.

[0081] In some embodiments, the optical system 100 satisfies the following relational expression: 2.7<fi / R1<3.2; where R1 is the radius of curvature of the object-side surface S1 of the first lens L1 at the optical axis. When the optical system 100 satisfies this relational expression, the surface profile complexity of the first lens L1 can be reduced, so that the increase of field curvature and distortion can be effectively suppressed, and the molding difficulty of the first lens L1 can be reduced at the same time.

[0082] In some embodiments, the optical system 100 satisfies the following relational expression: 1.8<R2 / fi<5.2; where R2 is the radius of curvature of the image-side surface S2 of the first lens L1 at the optical axis. When the optical system 100 satisfies this relational expression, the surface profile complexity of the first lens L1 can be reduced, so that the increase of field curvature and distortion can be effectively suppressed, and the molding difficulty of the first lens L1 can be reduced at the same time.

[0083] In some embodiments, the optical system 100 satisfies the following relational expression: -4<fi / R3<-2, where R3 is the radius of curvature of the object-side surface S3 of the second lens L2 at the optical axis. When the optical system 100 satisfies this relational expression, the surface profile complexity of the second lens L2 can be reduced, so that the increase of field curvature and distortion can be effectively suppressed, and the molding difficulty of the second lens L2 can be reduced at the same time.

[0084] In some embodiments, the optical system 100 satisfies the following relational expression: -3.8<fi / R4<-1.3, where R4 is the radius of curvature of the image-side surface S4 of the second lens L2 at the optical axis. When the optical system 100 satisfies this relational expression, the surface profile complexity of the second lens L2 can be reduced, so that the increase of field curvature and distortion can be effectively suppressed, and the molding difficulty of the second lens L2 can be reduced at the same time.

[0085] In some embodiments, the optical system 100 satisfies the following relational expression: -2<fi / R5<-1.1, where R5 is the radius of curvature of the object-side surface of the third lens L3 at the optical axis. When the optical system 100 satisfies this relational expression, the surface profile complexity of the third lens L3 can be reduced, so that the increase of field curvature and distortion can be effectively suppressed, and the molding difficulty of the third lens L3 can be reduced at the same time.

[0086] In some embodiments, the optical system 100 satisfies the following relational expression: 2<fi / R6<3.2, where R6 is the radius of curvature of the image-side surface of the third lens L3 at the optical axis. When the optical system 100 satisfies this relational expression, it can reduce the surface profile complexity of the third lens L3, thereby effectively suppressing the increase of field curvature and distortion, and simultaneously lowering the molding difficulty of the third lens L3.

[0087] In some embodiments, the optical system 100 satisfies the following relational expression: 4<fi / R7<6, where R7 is the radius of curvature of the object-side surface S7 of the fourth lens L4 at the optical axis. When the optical system 100 satisfies this relational expression, it can reduce the surface profile complexity of the fourth lens L4, thereby effectively suppressing the increase of field curvature and distortion, and simultaneously lowering the molding difficulty of the fourth lens L4.

[0088] In some embodiments, the optical system 100 satisfies the following relational expression: 2.2<fi / R8<3.5, where R8 is the radius of curvature of the image-side surface S8 of the fourth lens L4 at the optical axis. When the optical system 100 satisfies this relational expression, it can reduce the surface profile complexity of the fourth lens L4, thereby effectively suppressing the increase of field curvature and distortion, and simultaneously lowering the molding difficulty of the fourth lens L4.

[0089] In some embodiments, the optical system 100 satisfies the following relational expression: 0.78<SD1 / IMGH<1.02. Wherein SD1 is the maximum effective half-aperture of the object-side surface of the first lens L1. When the optical system 100 satisfies this relational expression, it can reasonably control the ratio of the maximum effective half-aperture of the optical system 100 to the image plane IMG, realize the convergence of light within the field of view, and at the same time enable the maximum effective half-aperture of the optical system 100 to match the size of the image plane of the optical system 100, which is beneficial to improving the space utilization rate of the optical system 100.

[0090] In some embodiments, the optical system 100 satisfies the following relational expression: 1.3<SD1 / SD8<1.65. Wherein SD1 is the maximum effective half-aperture of the object-side surface of the first lens L1, and SD8 is the maximum effective half-aperture of the image-side surface S8 of the fourth lens L4. When this relational expression is satisfied, the ratio of the maximum effective half-aperture of the object-side surface of the first lens L1 to the maximum effective half-aperture of the image-side surface of the fourth lens L4 can be reasonably controlled, so that there is no large step difference between the first lens L1 and the fourth lens L4, thereby allowing light to enter the second lens group G2 from the first lens group G1 more gently.

[0091] In some embodiments, the optical system 100 satisfies the following relational expression: 1.25 < SD1 / SD5 < 1.45. Herein, SD5 is the maximum effective half-aperture of the object-side surface S5 of the third lens L3. When the optical system 100 satisfies this relational expression, the maximum effective half-aperture of the object-side surface of the first lens L1 and the maximum effective half-aperture of the object-side surface of the third lens L3 can be adapted to each other, and the size difference between the two will not be too large, so that as many light rays as possible can enter the second lens group G2 through the first lens group G1, which is further beneficial to improving the imaging quality of the optical system.

[0092] In some embodiments, the optical system 100 satisfies the following relational expression: 2.1 < GL2 / GL1 < 3.2. Herein, GL2 is the distance on the optical axis from the object-side surface of the third lens L3 to the image-side surface of the fourth lens L4 in the second lens group G2 (that is, the distance occupied by the second lens group G2 on the optical axis), and GL1 is the distance on the optical axis from the object-side surface of the first lens L1 to the image-side surface of the second lens L2 in the first lens group G1 (that is, the distance occupied by the entire first lens group G1 on the optical axis). When this relational expression is satisfied, the dimensions of the first lens group G1 and the second lens group G2 on the optical axis can be reasonably controlled, so that the miniaturization design of the optical system 100 is realized, and the processing and assembly of the first lens group G1 and the second lens group G2 are also facilitated.

[0093] In some embodiments, the optical system 100 satisfies the following relational expression: 2.3 < CT1 / CT2 < 3.3. Herein, CT1 is the thickness of the first lens L1 on the optical axis, and CT2 is the thickness of the second lens L2 on the optical axis. By limiting the ratio of the thickness of the first lens L1 on the optical axis to the thickness of the second lens L2 on the optical axis, the thicknesses of the first lens L1 and the second lens L2 can be reasonably controlled, the miniaturization design of the optical system 100 is realized, and the sensitivity of the optical system 100 is favorably reduced at the same time.

[0094] In some embodiments, the optical system 100 satisfies the following relational expression: 1.3 < CT3 / CT4 < 2.2. Herein, CT3 is the thickness of the third lens L3 on the optical axis, and CT4 is the thickness of the fourth lens L4 on the optical axis. When this relational expression is satisfied, the thicknesses of the fourth lens L4 and the third lens L3 can be effectively controlled, so as to control the overall thickness of the second lens group, realize the miniaturization design of the optical system 100, and help reduce the sensitivity of the optical system 100 at the same time.

[0095] In some embodiments, the optical system 100 satisfies the following relational expression: 1.5<CT2 / CT3<2.45. When this relational expression is satisfied, the thicknesses of the second lens L2 and the third lens L3 can be effectively controlled, so that the overall thickness of the optical system is concentrated in the first lens group G1, which realizes the miniaturization of the optical system 100 and is also beneficial to reducing the sensitivity of the optical system 100.

[0096] In some embodiments, the optical system 100 satisfies the following relational expression: 1<TDm / TDi<1.1. Wherein, TDm is the distance on the optical axis from the object side of the first lens L1 to the image side of the fourth lens L4 when the optical system is in a near-focus state, and TDi is the distance on the optical axis from the object side of the first lens L1 to the image side of the fourth lens L4 when the optical system is in a far-focus state. When this relational expression is satisfied, the movement amount of the first lens group G1 of the optical system in the near-focus state and the far-focus state can be controlled to be appropriate, which is beneficial to controlling the movement stroke of the first lens group G1.

[0097] In some embodiments, the optical system 100 satisfies the following relational expression: 5.3<TTL / ImgH<5.7. Wherein, TTL is the optical path length of the optical system 100 (that is, the total optical path length of the optical system 100). When this relational expression is satisfied, the relationship between the optical system in the far-focus state and the image plane IMG of the optical system 100 can be controlled, so that the lens group of the optical system can adapt to the image plane of the optical system 100, which is beneficial for light to enter the image plane better.

[0098] In some embodiments, the optical system 100 satisfies the following relational expression: 5.3<TTL / ATTL<5.7. Wherein, ATTL refers to the sum of the distance from the object side of the first lens L1 to the object side of the reflecting member LP in the optical axis direction and the thickness L of the reflecting member LP (see Figure 2A ). When this relational expression is satisfied, the length of the optical system in the optical axis direction is significantly smaller than the total optical path length of the optical system, which can effectively shorten the dimension of the optical system in the optical axis direction while achieving a long focal length, and is beneficial to the miniaturization of the optical system.

[0099] The optical system 100 of this embodiment will be described in detail below with reference to specific parameters.

[0100] First Embodiment

[0101] The schematic structural diagram of the optical system 100 disclosed in the first embodiment of the present application is as shown in Figure 1A , Figure 2AAs shown, the optical system 100 includes an aperture stop STO, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a reflector LP, and a filter IR, arranged sequentially along the optical axis from the object side to the image side. The first lens L1 and the second lens L2 constitute a first lens group G1, and the third lens L3 and the fourth lens L4 constitute a second lens group G2.

[0102] In this embodiment, the first lens L1 has positive refractive power, and its object-side surface S1 and image-side surface S2 are convex and concave near the optical axis, respectively. The second lens L2 has negative refractive power, its object-side surface S3 is concave near the optical axis, and its image-side surface S4 is convex near the optical axis. The third lens L3 has negative refractive power, and its object-side surface S5 and image-side surface S6 are both concave near the optical axis. The fourth lens L4 has positive refractive power, and its object-side surface S7 and image-side surface S8 are convex and concave near the optical axis, respectively.

[0103] In this embodiment, the reflector LP is a prism, the included angle α between the first reflecting surface and the first surface is 30°, and the included angle β between the second reflecting surface and the first surface is also 30°.

[0104] The optical system 100 of this application, through the aforementioned structural design—namely, utilizing the reflector LP to achieve optical path folding, and positioning the first lens group G1, the second lens group G2, and the imaging surface of the optical system 100 on the same side relative to the first surface RF1 of the reflector RF—enables the optical system 100 to possess miniaturization characteristics. When the optical system 100 is applied to electronic devices, it can adapt to the miniaturization design requirements of electronic devices. For example, taking a mobile phone as an example, when the optical system is used in a camera module assembled in a mobile phone as a rear camera module, the optical axes of the lens groups (first lens L1 to fourth lens L4) are approximately perpendicular to the back of the mobile phone (i.e., the surface of the back cover). The aperture of the lenses is not limited by the thickness of the mobile phone and can protrude fully or partially from the back of the mobile phone, avoiding excessive overall thickness and thus meeting the requirements for a thin and light mobile phone design. In addition, the image plane of the optical system is approximately parallel to the display surface of the mobile phone, which facilitates the installation of the photosensitive chip and reduces assembly difficulty.

[0105] Furthermore, the prism of this application adopts the method that the light-incident area LP10 and the light-outceasing area LP12 are located on the same surface and are roughly parallel to the back of the mobile phone, which makes the mobile phone thinner and lighter and more ergonomic.

[0106] It is understood that this optical system 100 can also be used for front-facing cameras or other mounting methods; the rear-facing camera mounting is only an example.

[0107] Specifically, the parameters of the optical system 100 are given in Table 1 below. The elements along the optical axis of the optical system 100, from the object side to the image side, are arranged sequentially from top to bottom according to Table 1. In the same lens, the surface with the smaller face number is the object-side surface of the lens, and the surface with the larger face number is the image-side surface of the lens. For example, face numbers 1 and 2 correspond to the object-side surface S1 and image-side surface S2 of the first lens L1, respectively. The Y-radius in Table 1 is the radius of curvature of the corresponding object-side or image-side surface at the optical axis. The first value in the "thickness" parameter column of the lens is the thickness of the lens along the optical axis, and the second value is the distance from the image-side surface of the lens to the next surface along the optical axis. The value of the stop STO in the "Thickness" parameter column represents the distance on the optical axis from the stop STO to the vertex of the next surface (the vertex refers to the intersection of the surface and the optical axis). By default, the direction from the object side of the first lens L1 to the image side of the last lens is the positive direction of the optical axis. When this value is negative, it indicates that the stop STO is set on the image side of the next surface vertex. If the stop STO thickness is positive, the stop STO is on the object side of the next surface vertex. It is understood that the units for the Y-radius, thickness, and focal length in Table 1 are all mm. Furthermore, the refractive index, Abbe number, etc., in Table 1 are obtained at a reference wavelength of 587.56 nm, and the focal length is obtained at a reference wavelength of 555 nm. Considering that the optical system 100 of this application can achieve internal focusing, it has a telephoto state and a near-focus state. Therefore, it has different object distances A in the telephoto state and the near-focus state. At the same time, in the telephoto state and the near-focus state, the air gap T23 (i.e., D in Table 1) between the image side surface S4 of the second lens L2 and the object side surface S5 of the third lens L3 in the optical axis direction is different, and the air gap (i.e., E in Table 1) between the image side surface S8 of the fourth lens L4 and the reflector LP in the optical axis direction is also different.

[0108] In Table 1, the thickness t1 corresponding to surface number 9 refers to the distance on the optical axis from the incident light region to the second surface; the thickness t2 corresponding to surface number 10 refers to the optical path length of the light reflected from the second surface to the first surface; the thickness t3 corresponding to surface number 11 refers to the optical path length of the light reflected from the first surface to the fourth surface; and the thickness t4 corresponding to surface number 12 refers to the distance on the optical axis from the light emitting region of the fourth surface to the first surface (see details in Table 1). Figure 1A ).

[0109] Based on this, Table 2 was compiled, which shows the values ​​of A, D, E, FNO, FOV, TTL, f, and ImgH in both telephoto and near-photo modes. In Table 2, the unit of FOV is deg, FNO has no unit, and the units of the other parameters are mm.

[0110] In the first embodiment, the total optical path length of the optical system is TTL = 20mm.

[0111] In addition, in Tables 1 and 3 below, surface numbers 1 and 2 correspond to the object side S1 and image side S2 of the first lens L1, respectively; surface numbers 3 and 4 correspond to the object side S3 and image side S4 of the second lens L2, respectively; and so on, surface numbers 7 and 8 correspond to the object side S7 and image side S8 of the fourth lens L4, respectively.

[0112] In the first embodiment, the object-side surface and image-side surface of any one of the first lens L1 to the fourth lens L4 are aspherical, and the surface shape x of each aspherical lens can be defined using, but is not limited to, the following aspherical formula:

[0113]

[0114] Where x is the distance vector from the vertex of the aspherical surface at a height of h along the optical axis; c is the curvature of the aspherical surface at the optical axis, c = 1 / Y (i.e., the paraxial curvature c is the reciprocal of the radius of curvature Y in Table 1 below); K is the conic coefficient; Ai is the i-th order correction coefficient of the aspherical surface. Table 3 below gives the higher-order coefficients A4, A6, A8, A10, A12, A14, and A16 that can be used for surfaces numbered 1-8 in the first embodiment.

[0115] Table 1

[0116]

[0117] Table 2

[0118] parameter A D E FNO TTL FOV ImgH f telephoto unlimited 0.30 0.826 2.26 20.00 26.7 3.6 14.92 Close focus 300.00 0.57 0.556 2.3 20.00 26.1 3.6 14.2

[0119] Table 3

[0120]

[0121]

[0122] Please see Figure 1B , Figure 2B (A) in the middle Figure 1B , Figure 2B Figure (A) shows the aberration curves of the optical system 100 in the first embodiment at wavelengths of 470 nm, 510 nm, 555 nm, 610 nm, and 650 nm in both the far-focus and near-focus states. The horizontal axis along the X-axis represents the focus shift, and the vertical axis along the Y-axis represents the image height, in mm. The field curvature curves represent the curvature of the meridional and sagittal imaging planes. As can be seen from the figure, the field curvature of the optical system 100 is small, and the field curvature and astigmatism of each field of view are well corrected, with clear imaging at both the center and edges of the field of view.

[0123] Please see Figure 1B , Figure 2B (B) in the middle Figure 1B , Figure 2B Figure (B) shows the distortion curve of the optical system 100 in this embodiment at a wavelength of 650 nm. The horizontal axis along the X-axis represents distortion, and the vertical axis along the Y-axis represents image height, both in mm. Figure 1B , Figure 2B As can be seen from (B) in the figure, the distortion of the optical system 100 is well corrected at a wavelength of 650nm.

[0124] Please see Figure 1C , Figure 2C The figures show the chromatic aberration curves of the optical system 100 in this embodiment at wavelengths of 470nm, 510nm, 555nm, 610nm, and 650nm, respectively, in both telephoto and near-focus states. Simultaneously, from... Figure 1C As can be seen, in the telephoto state, the maximum chromatic aberration value of this optical system is less than 1.6 μm, and it is mostly located within the Airy disk area. Figure 2C As can be seen, in near-focus mode, at the above wavelengths, the maximum chromatic difference of this optical system is less than 3μm and is basically located within the Airy disk region.

[0125] Second Embodiment

[0126] like Figure 3A , Figure 4A As shown, the optical system 100 of this application includes an aperture stop STO, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a reflector, and a filter IR, arranged sequentially along the optical axis from the object side to the image side. The first lens L1 and the second lens L2 constitute a first lens group G1, and the third lens L3 and the fourth lens L4 constitute a second lens group G2.

[0127] Specifically, the parameters of the optical system 100 are given in Table 4 below. The definitions of each parameter can be derived from the description of the foregoing embodiments and will not be repeated here. Correspondingly, Table 5 gives the values ​​of each parameter of the optical system in the telephoto and near-focus states. In this embodiment, the total optical path length TTL of the optical system 100 is 20 mm. Table 6 below gives the higher-order coefficients that can be used for each aspherical lens in the second embodiment.

[0128] Table 4

[0129]

[0130]

[0131] Table 5

[0132] parameter A D E FNO TTL FOV ImgH f telephoto unlimited 0.30 0.78 2.5 20.00 27.5 3.6 14.7 Close focus 300.00 0.57 0.497 2.54 20.00 25.4 3.6 14

[0133] Table 6

[0134]

[0135] Please see Figure 3B , Figure 4B ,Depend on Figure 3B , Figure 4B As can be seen from (A) the ray astigmatism diagram and (B) the distortion curve diagram, the astigmatism and distortion of the optical system 100 are well controlled, thus the optical system 100 of this embodiment has good imaging quality. Furthermore, regarding... Figure 3B , Figure 4B (A) and Figure 3B , Figure 4B The wavelengths corresponding to the curves in (B) can be referred to in the first embodiment regarding... Figure 1B , Figure 2B (A) Figure 1B , Figure 2B The content described in (B) will not be repeated here.

[0136] Similarly, please see Figure 3C , Figure 4C ,Depend on Figure 3C , Figure 4C The curves show that the maximum chromatic difference value of this optical system is less than 3 μm, and it is mostly located within the Airy disk region. Furthermore, regarding... Figure 3C , Figure 4C The wavelengths corresponding to each curve can be referred to in the first embodiment. Figure 1C , Figure 2C As shown in the figure, this embodiment will not be described in detail.

[0137] Third Embodiment

[0138] like Figure 5A , Figure 6A As shown, the optical system 100 of this application includes an aperture stop STO, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a reflector, and a filter IR, arranged sequentially along the optical axis from the object side to the image side. The first lens L1 and the second lens L2 constitute a first lens group G1, and the third lens L3 and the fourth lens L4 constitute a second lens group G2.

[0139] Specifically, the parameters of the optical system 100 are given in Table 7 below. The definitions of each parameter can be derived from the description of the foregoing embodiments and will not be repeated here. Correspondingly, Table 8 gives the values ​​of each parameter of the optical system in the telephoto and near-focus states. In this application, the total optical path length TTL of the optical system 100 is 19.85 mm. Table 9 below gives the higher-order coefficients that can be used for each aspherical lens in the third embodiment.

[0140] Table 7

[0141]

[0142] Table 8

[0143] parameter A D E FNO TTL FOV ImgH f telephoto unlimited 0.30 0.828 2.14 19.85 26.9 3.6 17.77 Close focus 300.00 0.59 0.538 2.18 19.85 26.3 3.6 14.1

[0144] Table 9

[0145]

[0146] Please see Figure 5B , Figure 6B ,Depend on Figure 5B , Figure 6B As can be seen from (A) the ray astigmatism diagram and (B) the distortion curve diagram, the astigmatism and distortion of the optical system 100 are well controlled, thus the optical system 100 of this embodiment has good imaging quality. Furthermore, regarding... Figure 5B , Figure 6B (A) and Figure 5B , Figure 6B The wavelengths corresponding to the curves in (B) can be referred to in the first embodiment regarding... Figure 1B , Figure 2B (A) Figure 1B , Figure 2B The content described in (B) will not be repeated here.

[0147] Similarly, please see Figure 5C , Figure 6C ,Depend on Figure 6C , Figure 6C The curves show that the maximum chromatic difference value of this optical system is less than 3 μm, and it is mostly located within the Airy disk region. Furthermore, regarding... Figure 5C , Figure 6C The wavelengths corresponding to each curve can be referred to in the first embodiment. Figure 1C , Figure 2C As shown in the figure, this embodiment will not be described in detail.

[0148] Fourth embodiment

[0149] like Figure 7A , Figure 8A As shown, the optical system 100 of this application includes an aperture stop STO, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a reflector, and a filter IR, arranged sequentially along the optical axis from the object side to the image side. The first lens L1 and the second lens L2 constitute a first lens group G1, and the third lens L3 and the fourth lens L4 constitute a second lens group G2.

[0150] Specifically, the parameters of the optical system 100 are given in Table 10 below. The definitions of each parameter can be derived from the description of the foregoing embodiments and will not be repeated here. Correspondingly, Table 11 gives the values ​​of each parameter of the optical system in the telephoto and near-focus states. In this embodiment, the total optical path length TTL of the optical system 100 is 19.6 mm. Table 12 gives the higher-order coefficients that can be used for each aspherical lens in the fourth embodiment.

[0151] Table 10

[0152]

[0153] Table 11

[0154] parameter A D E FNO TTL FOV ImgH f telephoto unlimited 0.30 0.774 2.266 19.60 28 3.6 14.178 Close focus 300.00 0.56 0.517 2.3 19.60 27.4 3.6 13.6

[0155] Table 12

[0156]

[0157]

[0158] Please see Figure 7B , Figure 8B ,Depend on Figure 7B , Figure 8B As can be seen from (A) the ray astigmatism diagram and (B) the distortion curve diagram, the astigmatism and distortion of the optical system 100 are well controlled, thus the optical system 100 of this embodiment has good imaging quality. Furthermore, regarding... Figure 7B , Figure 8B (A) and Figure 7B , Figure 8B The wavelengths corresponding to the curves in (B) can be referred to in the first embodiment regarding... Figure 1B , Figure 2B (A) Figure 1B , Figure 2B The content described in (B) will not be repeated here.

[0159] Similarly, please see Figure 7C , Figure 8C ,Depend on Figure 7C , Figure 8C The curves show that the maximum chromatic difference value of this optical system is less than 3 μm, and it is mostly located within the Airy disk region. Furthermore, regarding... Figure 7C , Figure 8C The wavelengths corresponding to each curve can be referred to in the first embodiment. Figure 1C , Figure 2C As shown in the figure, this embodiment will not be described in detail.

[0160] Fifth embodiment

[0161] like Figure 9A, Figure 10A As shown, the optical system 100 of this application includes an aperture stop STO, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a reflector, and a filter IR, arranged sequentially along the optical axis from the object side to the image side. The first lens L1 and the second lens L2 constitute a first lens group G1, and the third lens L3 and the fourth lens L4 constitute a second lens group G2.

[0162] Specifically, the parameters of the optical system 100 are given in Table 13 below. The definitions of each parameter can be derived from the description of the foregoing embodiments and will not be repeated here. Correspondingly, Table 14 gives the values ​​of each parameter of the optical system in the telephoto and near-focus states. In this embodiment, the total optical path length TTL of the optical system is 20.06 mm. Table 15 below gives the higher-order coefficients that can be used for each aspherical lens in the fifth embodiment.

[0163] Table 13

[0164]

[0165] Table 14

[0166]

[0167]

[0168] Table 15

[0169]

[0170] Please see Figure 9B , Figure 10B ,Depend on Figure 9B , Figure 10B As can be seen from (A) the ray astigmatism diagram and (B) the distortion curve diagram, the astigmatism and distortion of the optical system 100 are well controlled, thus the optical system 100 of this embodiment has good imaging quality. Furthermore, regarding... Figure 9B , Figure 10B (A) and Figure 9B , Figure 10B The wavelengths corresponding to the curves in (B) can be referred to in the first embodiment regarding... Figure 1B , Figure 2B (A) Figure 1B , Figure 2B The content described in (B) will not be repeated here.

[0171] Similarly, please see Figure 9C , Figure 10C ,Depend on Figure 9C , Figure 10CThe curves show that the maximum chromatic difference value of this optical system is less than 3 μm, and it is mostly located within the Airy disk region. Furthermore, regarding... Figure 9C , Figure 10C The wavelengths corresponding to each curve can be referred to in the first embodiment. Figure 1C , Figure 2C As shown in the figure, this embodiment will not be described in detail.

[0172] Refer to Table 16, which summarizes the ratios of the relationships in the first to fifth embodiments of this application.

[0173] Table 16

[0174]

[0175]

[0176] Please see Figure 11 This application also discloses a camera module 200, which includes an image sensor 201 and an optical system 100 as described in any of the first to fifth embodiments of the first aspect above. The image sensor 201 is disposed on the image side of the optical system 100. The optical system 100 is used to receive the light signal of the subject and project it onto the image sensor 201. The image sensor 201 is used to convert the light signal corresponding to the subject into an image signal, which will not be elaborated here. It is understood that the camera module 200 with the above-described optical system 100 has all the technical effects of the above-described optical system 100, and can achieve miniaturization design while reducing the difficulty of zoom design and realizing mass production design. Since the above-described technical effects have been described in detail in the embodiments of the optical system 100, they will not be repeated here.

[0177] Please see Figure 12 This application also discloses an electronic device 300, which includes a housing 301 and the aforementioned camera module 200, with the camera module 200 disposed within the housing. Specifically, the camera module 200 can be disposed inside the housing 301 or on the housing 301. The electronic device 300 can be, but is not limited to, a mobile phone, tablet computer, laptop computer, smartwatch, monitor, etc. It is understood that the electronic device 300 with the aforementioned camera module 200 also possesses all the technical effects of the aforementioned optical system 100. That is, it can achieve miniaturization while reducing the difficulty of zoom design, enabling mass production design. Since the aforementioned technical effects have been described in detail in the embodiments of the optical system 100, they will not be repeated here.

[0178] The optical system, camera module, and electronic device disclosed in the embodiments of this application have been described in detail above. Specific examples have been used to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the optical system, camera module, and electronic device of this application and their core ideas. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of this application. Therefore, the content of this specification should not be construed as a limitation of this application.

Claims

1. An optical system, characterized in that, There are four lenses with refractive power, and the optical system includes, arranged in order from the object side to the image side along the optical axis: a first lens group, which includes a first lens and a second lens arranged in order from the object side to the image side along the optical axis, the first lens has positive refractive power, 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, the second lens has negative refractive power, the object side surface of the second lens is concave at the near optical axis, and the image side surface of the second lens is convex at the near optical axis; and a second lens group, which includes a third lens and a fourth lens arranged in order from the object side to the image side along the optical axis, the third lens has negative refractive power, and both the object side surface and the image side surface of the third lens are concave at the near optical axis, the fourth lens has positive refractive power, the object side surface of the fourth lens is convex at the near optical axis, and the image side surface of the fourth lens is concave at the near optical axis; wherein the first lens group is fixed relative to the image plane of the optical system, and the second lens group is movable along the optical axis direction; The optical system satisfies the following relational expressions: 24deg<FOV<30deg, 1.95<FNO<2.7; where FOV is the maximum field of view of the optical system, and FNO is the f-number of the optical system.

2. The optical system according to claim 1, characterized in that, The optical system satisfies the following relational expressions: 1.9<fi / f1<2.3, and / or, -30<f2 / fi<-2, and / or, -3.1<fi / f3<-2.2, and / or, 0.55<f4 / fi<1.1; where f1 is the focal length of the first lens, f2 is the focal length of the second lens, f3 is the focal length of the third lens, f4 is the focal length of the fourth lens, and fi is the focal length of the optical system in the far-focus state.

3. The optical system according to claim 1, characterized in that, The optical system satisfies the following relational expressions: 2.7<fi / R1<3.2, and / or, 1.8<R2 / fi<5.2, and / or, -4<fi / R3<-2, and / or, -3.8<fi / R4<-1.3, and / or, -2<fi / R5<-1.1, and / or, 2<fi / R6<3.2, and / or, 4<fi / R7<6, and / or, 2.2<fi / R8<3.5; where R1 is the radius of curvature of the object side surface of the first lens at the optical axis, R2 is the radius of curvature of the image side surface of the first lens at the optical axis, R3 is the radius of curvature of the object side surface of the second lens at the optical axis, R4 is the radius of curvature of the image side surface of the second lens at the optical axis, R5 is the radius of curvature of the object side surface of the third lens at the optical axis, R6 is the radius of curvature of the image side surface of the third lens at the optical axis, R7 is the radius of curvature of the object side surface of the fourth lens at the optical axis, R8 is the radius of curvature of the image side surface of the fourth lens at the optical axis, and fi is the focal length of the optical system in the far-focus state.

4. The optical system according to claim 1, characterized in that, The optical system satisfies the following relational expressions: 5.3<TTL / IMGH<5.7, and / or, 1<TDm / TDi<1.1; wherein TTL is the optical path length of the optical system, IMGH is half of the image height corresponding to the maximum field of view of the optical system, TDm is the distance on the optical axis from the object-side surface of the first lens to the image-side surface of the fourth lens when the optical system is in a near-focus state, and TDi is the distance on the optical axis from the object-side surface of the first lens to the image-side surface of the fourth lens when the optical system is in a far-focus state.

5. The optical system according to claim 1, characterized in that, The optical system satisfies the following relational expressions: 0.78<SD1 / IMGH<1.02, and / or, 1.3<SD1 / SD8<1.65, and / or, 1.25<SD1 / SD5<1.45; wherein SD1 is the maximum effective half-aperture of the object-side surface of the first lens, SD8 is the maximum effective half-aperture of the image-side surface of the fourth lens, IMGH is half of the image height corresponding to the maximum field of view of the optical system, and SD5 is the maximum effective half-aperture of the object-side surface of the third lens.

6. The optical system according to claim 1, characterized in that, The optical system satisfies the following relational expressions: 2.3<CT1 / CT2<3.3, and / or, 1.3<CT4 / CT3<2.2, and / or, 1.5<CT2 / CT3<2.45; and / or, 2.1<GL2 / GL1<3.2; wherein CT1 is the thickness of the first lens on the optical axis, CT2 is the thickness of the second lens on the optical axis, CT3 is the thickness of the third lens on the optical axis, CT4 is the thickness of the fourth lens on the optical axis, GL2 is the distance on the optical axis from the object-side surface of the third lens to the image-side surface of the fourth lens in the second lens group, and GL1 is the distance on the optical axis from the object-side surface of the first lens to the image-side surface of the second lens in the first lens group.

7. The optical system according to claim 1, characterized in that, The optical system satisfies the following relational expressions: 1<fi / fm<1.1, and / or, 1<FOVi / FOVm<1.1, and / or, 1<FNOm / FNOi<1.1; wherein fi is the focal length of the optical system in the far-focus state, fm is the focal length of the optical system in the near-focus state, FOVm is the focal length of the optical system in the near-focus state, FOVi is the focal length of the optical system in the far-focus state, FNOm is the f-number of the optical system in the near-focus state, and FNO is the f-number of the optical system in the far-focus state.

8. The optical system according to claim 1, characterized in that, The optical system further comprises a reflecting member, the reflecting member has a first surface, a first reflecting surface and a second reflecting surface, the first reflecting surface is connected to one side of the first surface, the second reflecting surface is connected to the other side of the first surface, and the second reflecting surface is connected to the first reflecting surface; The first lens group, the second lens group and the image plane of the optical system are located on the same side relative to the first surface; The imaging light passes sequentially through the first mirror group and the second mirror group and is transmitted through the first surface into the reflector. It is reflected by the first reflective surface back to the first surface, reflected by the first surface to the second reflective surface, reflected by the second reflective surface back to the first surface, and transmitted through the first surface to the imaging surface of the optical system.

9. A camera module, characterized in that, The camera module includes an image sensor and an optical system as described in any one of claims 1-8, wherein the image sensor is disposed on the image side of the optical system.

10. An electronic device, characterized in that, The electronic device includes a housing and a camera module as described in claim 9, wherein the camera module is disposed in the housing.

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