Optical system, camera module and terminal equipment

Abstract

According to the optical system, the camera module and the terminal equipment provided by the invention, the positive refractive power design of the first lens is matched with the design that the object side surface is the convex surface, so that the light collection capability is improved; due to the design that the second lens has positive refractive power and the object side surface of the second lens is a convex surface, the emergent light of the first lens can be effectively transited and adjusted; the positive refractive power of the third lens is matched with the design that the object side surface and the image side surface are respectively a concave surface and a convex surface, so that the propagation path of the light beam can be further optimized; the negative refractive power of the fourth lens is matched with the design that the object side surface and the image side surface of the fourth lens are respectively a convex surface and a concave surface, so that the effects of balancing system aberration and compressing the total length of the optical system are achieved on the imaging side. According to the optical system, imaging can be carried out based on the infrared band, and meanwhile the requirements of large aperture, high imaging quality, optical system miniaturization design and stable imaging in a dark light environment are met.

Description

Technical Field

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

[0002] In recent years, with the rapid iteration and upgrading of portable electronic products such as mobile phones and tablets, the market's performance requirements for imaging lenses in portable electronic products have become increasingly diversified. In application scenarios such as iris recognition, imaging lenses not only need to have imaging capabilities based on the infrared band, but also need to meet the requirements of large aperture and high imaging quality, so as to adapt to diverse imaging needs and improve the lens's compatibility with different imaging environments.

[0003] While current portable electronic product imaging lenses have achieved relatively large apertures, in the pursuit of high imaging quality, it is often difficult to simultaneously achieve full-screen image clarity, lens miniaturization, and stable imaging in low-light environments. Summary of the Invention

[0004] This application provides an optical system, camera module, and terminal device that can perform infrared imaging while meeting the requirements of large aperture, high imaging quality, miniaturized optical system design, and stable imaging in low-light environments.

[0005] To achieve the above objectives, in a first aspect, this application discloses an optical system comprising four lenses with refractive power, including a first lens, a second lens, a third lens, and a fourth lens arranged sequentially along the optical axis from the object side to the image side; The first lens has positive refractive power, the object side of the first lens is convex near the optical axis, and the image side of the first lens is concave near the optical axis. The second lens has positive refractive power, and the object side of the second lens is convex near the optical axis; The third lens has positive refractive power, the object side of the third lens is concave near the optical axis, and the image side of the third lens is convex near the optical axis. The fourth lens has negative refractive power, the object side of the fourth lens is convex near the optical axis, and the image side of the fourth lens is concave near the optical axis. The optical system satisfies the following relationship: 84deg < FOV < 103deg and 2.24 ≤ FNO ≤ 2.71; Wherein, FOV is the maximum field of view of the optical system, and FNO is the aperture number of the optical system.

[0006] In the optical system provided by this application, in order to be able to image based on the infrared band while meeting the requirements of large aperture, high imaging quality, miniaturized design of the optical system, and stable imaging in low-light environments, the number of lenses in the optical system is controlled to four. At the same time, by reasonably distributing the refractive power and surface parameters of each lens, the overall optical length is effectively shortened while ensuring imaging performance. Specifically, the positive refractive power design of the first lens in combination with the design of its object side as a convex surface is conducive to enhancing the light collection ability; the positive refractive power of the second lens and the design of its object side as a convex surface can effectively transition and adjust the light emitted by the first lens, reducing the generation of marginal aberrations; the positive refractive power of the third lens in combination with the design of its object side as a concave surface and image side as a convex surface can further optimize the light beam propagation path and improve imaging clarity; the negative refractive power of the fourth lens in combination with the design of its object side as a convex surface and image side as a concave surface plays a role in balancing the aberrations of the optical system and compressing the overall length of the optical system on the imaging side. At the same time, it can also suppress the light emission angle, which is beneficial to the incidence of a large range of light onto the imaging surface.

[0007] The optical system satisfies the relationship 84deg < FOV < 103deg, which is conducive to achieving large-field-angle imaging, enabling the capture of a wider scene range, and enhancing the perception ability of the optical system for the surrounding environment.

[0008] The optical system satisfies the relationship 2.24 ≤ FNO ≤ 2.71. The optical system has the characteristic of a large aperture, ensuring a large light input amount for the optical system, thereby improving the exposure rate of the optical system under low-light conditions (such as dusk, night, etc.), while ensuring good resolution of the optical system and enhancing the imaging quality of the optical system.

[0009] As an optional implementation manner, the optical system satisfies the following relationship: 0.99 < TTL / IMGH < 1.19; Where, TTL is the distance from the object side of the first lens to the imaging surface of the optical system in the optical axis direction, and IMGH is half of the image height corresponding to the maximum field of view angle of the optical system.

[0010] The optical system satisfies the relationship 0.99 < TTL / IMGH < 1.19. By reasonably configuring the ratio relationship between the overall length and half image height of the optical system, it can not only ensure that the optical system has sufficient imaging space but also effectively control the overall size of the optical system, achieving the miniaturized design of the optical system, thus better adapting to the thin and light requirements of portable electronic products.

[0011] As an optional implementation manner, the optical system satisfies the following relationship: 1.2 < f1 / f < 1.6, and / or, 8.4 < f2 / f < 164, and / or, 1.5 < f3 / f < 2.36, and / or, -2.3 < f4 / f < -1; where f is the focal length of the optical system, 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, and f4 is the focal length of the fourth lens.

[0012] When the optical system satisfies the above relationships, by optimizing the ratio of the focal length of each lens to the total focal length of the system, the refractive power of each lens can be reasonably distributed, ensuring that while achieving a large field angle and a large aperture, the optical system effectively balances aberrations and improves the clarity and uniformity of imaging.

[0013] Specifically, when the optical system satisfies the relationship 1.2 < f1 / f < 1.6, it can ensure that it has a strong light converging ability, which is beneficial to the aberration correction and optical path optimization of the subsequent lenses; when the optical system satisfies the relationship 8.4 < f2 / f < 164, the ratio range of the focal length of the second lens to the total focal length of the system is large, which helps to flexibly adjust the light propagation path and compress the overall optical length; when the optical system satisfies the relationship 1.5 < f3 / f < 2.36, it can avoid excessive refractive power of a single lens, avoid introducing unnecessary aberrations, enhance the ability to control the light beam, and compress the overall optical length; when the optical system satisfies the relationship -2.3 < f4 / f < -1, it can effectively balance the aberrations of the system, avoid excessive convergence of on-axis light, and effectively adjust the field curvature.

[0014] As an optional implementation manner, the optical system satisfies the following relationships: 2.04 < f / R1 < 2.85, and / or, 1 < f / R2 < 1.48, and / or, 1.41 < R3 / f < 112.2, and / or, 1.6 < |R4| / f < 20.5, and / or, -1.74 < R5 / f < -1.25, and / or, -1.92 < f / R6 ≤ -1.36, and / or, 2.2 < f / R7 < 3.7, and / or, 4.3 < f / R8 < 5.43; Where, f is the focal length of the optical system, R1 is the curvature radius of the object side of the first lens on the optical axis, R2 is the curvature radius of the image side of the first lens on the optical axis, R3 is the curvature radius of the object side of the second lens on the optical axis, R4 is the curvature radius of the image side of the second lens on the optical axis, R5 is the curvature radius of the object side of the third lens on the optical axis, R6 is the curvature radius of the image side of the third lens on the optical axis, R7 is the curvature radius of the object side of the fourth lens on the optical axis, and R8 is the curvature radius of the image side of the fourth lens on the optical axis.

[0015] When the optical system satisfies the above relational expressions, by precisely controlling the ratio of the curvature radius of each lens surface to the system focal length, the surface shape design of each lens can be optimized, thereby effectively correcting various aberrations such as spherical aberration and coma, and improving the imaging quality of the optical system.

[0016] Specifically, when the optical system satisfies the relational expressions 2.04 < f / R1 < 2.85 and / or 1 < f / R2 < 1.48, it can ensure that the object side and the image side of the first lens have appropriate bending degrees, reduce the incident angle of light on the lens surface, and reduce the generation of aberrations while converging light; when the optical system satisfies the relational expressions 1.41 < R3 / f < 112.2 and / or 1.6 < |R4| / f < 20.5, it helps the second lens to reasonably transition and adjust light; when the optical system satisfies the relational expressions -1.74 < R5 / f < -1.25 and / or -1.92 < f / R6 ≤ -1.36, it can better optimize the propagation path in the third lens; when the optical system satisfies the relational expressions 2.2 < f / R7 < 3.7 and / or 4.3 < f / R8 < 5.43, it can ensure that the fourth lens plays an effective role in balancing aberrations and adjusting the overall optical length.

[0017] As an optional implementation manner, the optical system satisfies the following relational expressions: 1.08 < CT1 / CT2 < 1.62, and / or, 0.89 < CT1 / CT3 < 1.25, and / or, 1 ≤ CT1 / CT4 < 1.25; Where, 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, and CT4 is the thickness of the fourth lens on the optical axis.

[0018] The optical system satisfies the relation 1.08 < CT1 / CT2 < 1.62, which can ensure that the thickness ratio of the first lens to the second lens is within a reasonable range, avoiding both the increase in the weight of the optical system and the rise in assembly difficulty caused by the excessive thickness of the first lens, and preventing the second lens from being too thin to affect its structural stability and the refractive power adjustment effect. Thus, while ensuring the optical performance of the lens, the overall structural design is optimized.

[0019] The optical system satisfies the relation 0.89 < CT1 / CT3 < 1.25. By controlling the thickness ratio of the first lens to the third lens, they can form a good cooperation during the light propagation process, avoiding the imbalance of aberration correction caused by excessive thickness difference, which helps to improve the imaging quality of the optical system.

[0020] The optical system satisfies the relation 1 ≤ CT1 / CT4 < 1.25, which can keep the thickness of the first lens and the fourth lens in a proper relationship. While ensuring that the fourth lens has sufficient negative refractive power to balance the system aberration, it avoids the adverse impact on the miniaturization design of the optical system caused by its excessive thickness.

[0021] As an optional implementation, the optical system satisfies the following relations: 1.01 < CT1 / AT12 < 1.13, and / or, 0.98 < AT23 / CT1 < 1.12, and / or, 0.68 < CT1 / AT34 < 2.2; Where CT1 is the thickness of the first lens on the optical axis, AT12 is the axial distance between the first lens and the second lens on the optical axis, AT23 is the axial distance between the second lens and the third lens on the optical axis, and AT34 is the axial distance between the third lens and the fourth lens on the optical axis.

[0022] The optical system satisfies the relation 1.01 < CT1 / AT12 < 1.13. By controlling the ratio of the thickness of the first lens to the distance between the first lens and the second lens within this range, it can ensure that the light enters the second lens at a proper angle after passing through the first lens, avoiding the light divergence caused by excessive distance or the aberration superposition caused by too small distance, thus optimizing the light transition effect between the lenses.

[0023] The optical system satisfies the relation 0.98 < AT23 / CT1 < 1.12. Reasonably setting the ratio of the distance between the second lens and the third lens to the thickness of the first lens helps to provide sufficient adjustment space for light propagation while ensuring the compact structure of the optical system, further enhancing the flexibility of aberration correction.

[0024] The optical system satisfies the relation 0.68 < CT1 / AT34 < 2.2. By controlling the ratio of the thickness of the first lens to the distance between the third lens and the fourth lens, the propagation path of light in the rear part of the lens group can be balanced, ensuring that the fourth lens can effectively correct the light beam, while avoiding an increase in the overall optical length or a decrease in the imaging quality caused by an inappropriate distance.

[0025] As an optional implementation manner, the optical system satisfies the following relations: 1.62 < SD8 / SD6 < 1.84, and / or, 2.67 < SD8 / SD4 < 2.88, and / or, 3.08 < SD8 / SD2 < 4.1, and / or, 2.96 < SD8 / SD1 < 4.63; where SD1 is half of the maximum effective aperture of the object side of the first lens, SD2 is half of the maximum effective aperture of the image side of the first lens, SD4 is half of the maximum effective aperture of the image side of the second lens, SD6 is half of the maximum effective aperture of the image side of the third lens, and SD8 is half of the maximum effective aperture of the image side of the fourth lens.

[0026] The optical system satisfies the relation 1.62 < SD8 / SD6 < 1.84. By reasonably controlling the ratio of the maximum effective apertures of the image side of the fourth lens to the image side of the third lens, it can ensure that the light enters the fourth lens at an appropriate angle after passing through the third lens, avoiding edge light loss or uneven image plane illumination caused by too large aperture differences, thereby improving the imaging quality of the optical system.

[0027] The optical system satisfies the relation 2.67 < SD8 / SD4 < 2.88, which helps to balance the aperture relationship between the image side of the second lens and the image side of the fourth lens, causing the light to gradually converge during propagation and reducing the energy loss of the light beam at the lens edge.

[0028] The optical system satisfies the relation 3.08 < SD8 / SD2 < 4.1. By controlling the ratio of the maximum effective apertures of the image side of the fourth lens to the image side of the first lens, the beam convergence ability of the optical system can be effectively adjusted, ensuring that the light at the edge of the imaging plane is evenly distributed and improving the imaging quality at a large field angle.

[0029] The optical system satisfies the relation 2.96 < SD8 / SD1 < 4.63, which can reasonably match the aperture sizes of the object side of the first lens and the image side of the fourth lens. While ensuring that the first lens has sufficient light collection ability, the fourth lens can effectively converge the light beam, avoiding an increase in the aberration at the edge of the imaging plane caused by too wide a light beam, thereby taking into account the requirements of a large field angle and high imaging quality.

[0030] As an optional implementation manner, the optical system satisfies the following relational expressions: 4.09 < IMGH / SD1 < 6.62, and / or, 1.38 < IMGH / SD8 < 1.46; where IMGH is half of the image height corresponding to the maximum field angle of the optical system, SD1 is half of the maximum effective aperture of the object side surface of the first lens, and SD8 is half of the maximum effective aperture of the image side surface of the fourth lens.

[0031] When the optical system satisfies the relational expression 4.09 < IMGH / SD1 < 6.62, by reasonably setting the ratio of half of the image height to half of the maximum effective aperture of the object side surface of the first lens, it is possible to ensure the imaging ability of the optical system with a large field angle while avoiding the increase in the volume and weight of the optical system caused by the too large aperture of the first lens, thereby optimizing the miniaturization design of the optical system on the basis of improving the environmental perception range.

[0032] When the optical system satisfies the relational expression 1.38 < IMGH / SD8 < 1.46, it can ensure that the ratio of half of the image height to half of the maximum effective aperture of the image side surface of the fourth lens is within an appropriate range, which not only ensures that the imaging surface has sufficient size to present a clear and complete image, but also avoids the bloated structure of the optical system caused by the too large aperture of the image side surface of the fourth lens, and helps to achieve the balance between the thinness and lightness of the optical system and high imaging quality.

[0033] In a second aspect, the present application also discloses an imaging module, which includes an image sensor and the optical system as described in the first aspect above, and the image sensor is disposed on the image side of the optical system.

[0034] In a third aspect, the present application also discloses a terminal device, which includes a housing and the imaging module as described in the second aspect above, and the imaging module is disposed in the housing.

[0035] Compared with the prior art, the beneficial effects of the present application are: In the optical system provided in this application, in order to achieve infrared imaging while satisfying the requirements of large aperture, high imaging quality, miniaturized optical system design, and stable imaging in low-light environments, the number of lenses in the optical system is controlled to four. Simultaneously, by rationally allocating the refractive power and surface parameters of each lens, the total optical length is effectively shortened while ensuring imaging performance. Specifically, the positive refractive power design of the first lens, combined with its convex object-side surface, is beneficial for improving light collection ability; the positive refractive power of the second lens, along with its convex object-side surface, effectively transitions and adjusts the light emitted from the first lens, reducing edge aberrations; the positive refractive power of the third lens, combined with its concave object-side and convex image-side surfaces, further optimizes the beam propagation path and improves imaging clarity; the negative refractive power of the fourth lens, combined with its convex object-side and concave image-side surfaces, balances optical system aberrations and compresses the total optical system length on the imaging side, while also suppressing the light emission angle, which is beneficial for a wide range of light incident on the imaging surface.

[0036] The optical system satisfies the relationship 84deg < FOV < 103deg, which is beneficial for achieving large field-of-view imaging, capturing a wider range of scenes, and improving the optical system's ability to perceive the surrounding environment.

[0037] The optical system satisfies the relation 2.24≤FNO≤2.71, and has the characteristic of a large aperture, which ensures that the optical system has a large amount of light intake. This can improve the exposure rate of the optical system under low light conditions (such as dusk, night, etc.), while ensuring good resolution and improving the imaging quality of the optical system. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0039] Figure 1 This is a schematic diagram of the optical system disclosed in Embodiment 1 of this application; Figure 2 These are the spherical aberration diagram (mm), astigmatism diagram (mm), and distortion diagram (%) of the optical system disclosed in Embodiment 1 of this application; Figure 3 This is a schematic diagram of the optical system disclosed in Embodiment 2 of this application; Figure 4 These are the spherical aberration diagram (mm), astigmatism diagram (mm), and distortion diagram (%) of the optical system disclosed in Embodiment 2 of this application; Figure 5 This is a schematic diagram of the optical system disclosed in Embodiment 3 of this application; Figure 6 These are the spherical aberration diagram (mm), astigmatism diagram (mm), and distortion diagram (%) of the optical system disclosed in Embodiment 3 of this application; Figure 7 This is a schematic diagram of the optical system disclosed in Embodiment 4 of this application; Figure 8 These are the spherical aberration diagram (mm), astigmatism diagram (mm), and distortion diagram (%) of the optical system disclosed in Embodiment 4 of this application; Figure 9 This is a schematic diagram of the optical system disclosed in Embodiment 5 of this application; Figure 10 These are the spherical aberration diagram (mm), astigmatism diagram (mm), and distortion diagram (%) of the optical system disclosed in Embodiment 5 of this application; Figure 11 This is a schematic diagram of the camera module disclosed in this application; Figure 12 This is a structural diagram of the terminal device disclosed in this application when it is a mobile phone. Detailed Implementation

[0040] 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.

[0041] In this application, the terms "upper," "lower," "front," "rear," "top," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. These terms are primarily for the purpose of better describing this application and its embodiments, and are not intended to limit the indicated device, element, or component to having a specific orientation, or to be constructed and operated in a specific orientation.

[0042] Furthermore, in addition to indicating location or positional relationship, some of the aforementioned terms may also have other meanings. For example, the term "above" may also be used in some cases to indicate a certain dependency or connection relationship. Those skilled in the art can understand the specific meaning of these terms in this application based on the specific circumstances.

[0043] Furthermore, the term "setup" should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral structure; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection via an intermediate medium, or an internal connection between two devices, components, or parts. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0044] Furthermore, the terms "first," "second," etc., are primarily used to distinguish different devices, components, or parts (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, components, or parts. Unless otherwise stated, "a plurality of" means two or more.

[0045] The technical solution of this application will be further described below with reference to the embodiments and accompanying drawings.

[0046] Please see Figure 1 This application discloses an optical system 100, which includes a first lens L1, a second lens L2, a third lens L3, and a fourth lens L4 arranged sequentially along the optical axis from the object side to the image side. During imaging, light rays enter the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 sequentially from the object side of the first lens L1, and are finally imaged on the imaging surface 101 of the optical system 100.

[0047] In some embodiments, the first lens L1 has positive refractive power, the second lens L2 has positive refractive power, the third lens L3 has positive refractive power, and the fourth lens L4 has negative refractive power.

[0048] In some embodiments, the object-side surface S1 of the first lens L1 is convex near the optical axis, and the image-side surface S2 of the first lens L1 is concave near the optical axis; 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 can be either convex or concave near the optical axis; the object-side surface S5 of the third lens L3 is concave near the optical axis, and the image-side surface S6 of the third lens L3 is convex near the optical axis; 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.

[0049] In the optical system 100 provided in this application, in order to achieve large aperture, high imaging quality, miniaturized design of the optical system 100, and stable imaging in low light environment while enabling imaging based on the infrared band, the number of lenses in the optical system 100 is controlled to four. At the same time, by reasonably allocating the refractive power and surface parameters of each lens, the total optical length is effectively shortened while ensuring imaging performance. Specifically, the positive refractive power design of the first lens L1, combined with the convex design of its object side S1, helps to improve the light collection capability; the positive refractive power of the second lens L2, combined with the convex design of its object side S3, can effectively transition and adjust the light emitted from the first lens, reducing the generation of edge aberrations; the positive refractive power of the third lens L3, combined with the concave and convex designs of its object side S5 and image side S6 respectively, can further optimize the beam propagation path and improve image clarity; the negative refractive power of the fourth lens L4, combined with the convex and concave designs of its object side S7 and image side S8 respectively, plays a role in balancing the aberrations of the optical system 100 and compressing the total length of the optical system 100 on the imaging side, while also suppressing the light emission angle, which is conducive to a large range of light entering the imaging surface 101.

[0050] Optionally, all lenses in the optical system 100 may be made of glass, or all may be made of plastic, or some lenses may be made of glass and some lenses may be made of plastic.

[0051] Optionally, the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 are all made of plastic.

[0052] Optionally, the first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 are all aspherical lenses.

[0053] In some embodiments, the optical system 100 further includes an aperture stop 102, which may be an aperture stop and / or a field stop, and may be disposed between the object plane of the optical system 100 and the object side surface S1 of the first lens L1. It is understood that in other embodiments, the aperture stop 102 may also be disposed between other lenses, and the setting may be adjusted according to the actual situation. This embodiment does not make specific limitations.

[0054] In some embodiments, the optical system 100 further includes a filter 110, which may be disposed between the image-side surface S8 of the fourth lens L4 and the imaging surface 101 of the optical system 100. Of course, in other embodiments, the filter 110 may also be disposed between other lenses, and the setting may be adjusted according to the actual situation. This embodiment does not impose specific limitations.

[0055] In this embodiment, the filter 110 is an infrared bandpass filter, which can filter out light of other wavelengths such as visible light and only allow infrared light to pass through. By filtering out light of other wavelengths such as visible light, the imaging quality is improved. The optical system 100 can be used as an infrared optical system, that is, the optical system 100 can also image and obtain better image effects in dim environments and other special application scenarios.

[0056] Of course, the filter 110 can also be an infrared cut-off filter 110, which can filter out light of other wavelengths such as infrared light, and only allow visible light to pass through, making the image more in line with the visual experience of the human eye. Preferably, the filter 110 can be made of glass. Of course, in other embodiments, the filter 110 can also be made of optical glass with a coating, or a filter 110 of other materials, which can be selected according to actual needs. This embodiment does not make specific limitations.

[0057] In some embodiments, the optical system 100 also includes a protective glass 120 disposed between the filter 110 and the imaging surface 101, so that it can be close to the image sensor 201 during subsequent assembly, thereby playing a protective role.

[0058] In some embodiments, the optical system 100 satisfies the relationship 84deg < FOV < 103deg, where FOV is the maximum field of view of the optical system 100. By reasonably controlling the maximum field of view of the optical system 100, it is beneficial to achieve large field of view imaging, capture a wider range of scenes, and improve the optical system 100's perception of the surrounding environment.

[0059] In some embodiments, the optical system 100 satisfies the relationship 2.24 ≤ FNO ≤ 2.71, where FNO is the aperture number of the optical system 100. By reasonably configuring the aperture number of the optical system 100, the optical system 100 has the characteristic of a large aperture, ensuring that the optical system 100 has a large amount of light intake, thereby improving the exposure rate of the optical system 100 under low light conditions (such as dusk, night, etc.), while ensuring good resolution of the optical system 100 and improving the imaging quality of the optical system 100.

[0060] In some embodiments, the optical system 100 satisfies the relationship 0.99 < TTL / IMGH < 1.19, where TTL is the distance from the object side surface S1 of the first lens L1 to the imaging surface 101 of the optical system 100 in the optical axis direction, and IMGH is half of the image height corresponding to the maximum field angle of the optical system 100. By reasonably configuring the ratio relationship between the total length of the optical system 100 and the half image height, it can not only ensure that the optical system 100 has sufficient imaging space, but also effectively control the overall size of the optical system 100, achieve the miniaturized design of the optical system 100, and thus better adapt to the thin and light requirements of portable electronic products.

[0061] In some embodiments, the optical system 100 satisfies the relationship 1.2 < f1 / f < 1.6, where f is the focal length of the optical system 100 and f1 is the focal length of the first lens L1. By reasonably configuring the ratio relationship between the focal length of the first lens L1 and the total focal length of the system, it can ensure that it has strong light converging ability, which is beneficial to the aberration correction and optical path optimization of the subsequent lenses.

[0062] In some embodiments, the optical system 100 satisfies the relationship 8.4 < f2 / f < 164, where f is the focal length of the optical system 100 and f2 is the focal length of the second lens L2. By reasonably configuring the ratio relationship between the focal length of the second lens L2 and the total focal length of the system, it helps to flexibly adjust the propagation path of light and compress the overall optical length.

[0063] In some embodiments, the optical system 100 satisfies the relationship 1.5 < f3 / f < 2.36, where f is the focal length of the optical system 100 and f3 is the focal length of the third lens L3. By reasonably configuring the ratio relationship between the focal length of the third lens L3 and the total focal length of the system, it can avoid the excessive refractive power of a single lens, avoid introducing unnecessary aberrations, enhance the ability to control the light beam, and compress the overall optical length.

[0064] In some embodiments, the optical system 100 satisfies the relationship -2.3 < f4 / f < -1, where f is the focal length of the optical system 100 and f4 is the focal length of the fourth lens L4. By reasonably configuring the ratio relationship between the focal length of the fourth lens L4 and the total focal length of the system, it can effectively balance the aberrations of the system, avoid the excessive convergence of the on-axis light, and effectively adjust the field curvature.

[0065] The optical system 100 satisfies the above relationships. By optimizing the ratio of the focal length of each lens to the total focal length of the system, it can reasonably distribute the refractive power of each lens, ensure that the optical system 100 effectively balances aberrations while achieving a large field angle and a large aperture, and improve the clarity and uniformity of imaging.

[0066] In some embodiments, the optical system 100 satisfies the relations 2.04 < f / R1 < 2.85 and / or 1 < f / R2 < 1.48, where f is the focal length of the optical system 100, R1 is the curvature radius of the object side surface S1 of the first lens L1 at the optical axis, and R2 is the curvature radius of the image side surface S2 of the first lens L1 at the optical axis. By controlling the ratio of the surface curvature radius of the first lens L1 to the system focal length, it is possible to ensure that the object side surface S1 and the image side surface S2 of the first lens L1 have appropriate curvatures, reduce the incident angle of light on the lens surface, and reduce aberration while converging light rays.

[0067] In some embodiments, the optical system 100 satisfies the relations 1.41 < R3 / f < 112.2 and / or 1.6 < |R4| / f < 20.5, where f is the focal length of the optical system 100, R3 is the curvature radius of the object side surface S3 of the second lens L2 at the optical axis, and R4 is the curvature radius of the image side surface S4 of the second lens L2 at the optical axis. By controlling the ratio of the surface curvature radius of the second lens L2 to the system focal length, it helps the second lens L2 to make reasonable transition and adjustment of light rays.

[0068] In some embodiments, the optical system 100 satisfies the relations -1.74 < R5 / f < -1.25 and / or -1.92 < f / R6 ≤ -1.36, where f is the focal length of the optical system 100, R5 is the curvature radius of the object side surface S5 of the third lens L3 at the optical axis, and R6 is the curvature radius of the image side surface S6 of the third lens L3 at the optical axis. By controlling the ratio of the surface curvature radius of the third lens L3 to the system focal length, it can better optimize the propagation path of the light beam in the third lens L3.

[0069] In some embodiments, the optical system 100 satisfies the relations 2.2 < f / R7 < 3.7 and / or 4.3 < f / R8 < 5.43, where f is the focal length of the optical system 100, R7 is the curvature radius of the object side surface S7 of the fourth lens L4 at the optical axis, and R8 is the curvature radius of the image side surface S8 of the fourth lens L4 at the optical axis. By controlling the ratio of the surface curvature radius of the fourth lens L4 to the system focal length, it can ensure that the fourth lens L4 plays an effective role in balancing aberration and adjusting the overall optical length.

[0070] By precisely controlling the ratio of the surface curvature radius of each lens to the system focal length, the optical system 100 satisfying the above relations can optimize the surface shape design of each lens, thereby effectively correcting various aberrations such as spherical aberration and coma, and improving the imaging quality of the optical system 100.

[0071] In some embodiments, the optical system 100 satisfies the relation 1.08 < CT1 / CT2 < 1.62, where 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 reasonably configuring the thickness ratio of the first lens L1 and the second lens L2 within a reasonable range, it is possible to avoid both the increase in the weight of the optical system 100 and the rise in assembly difficulty caused by the excessive thickness of the first lens L1, and also prevent the thinness of the second lens L2 from affecting its structural stability and refractive power regulation effect, thereby optimizing the overall structural design while ensuring the optical performance of the lens.

[0072] In some embodiments, the optical system 100 satisfies the relation 0.89 < CT1 / CT3 < 1.25, where CT1 is the thickness of the first lens L1 on the optical axis, and CT3 is the thickness of the third lens L3 on the optical axis. By controlling the thickness ratio of the first lens L1 and the third lens L3, it is possible to enable them to form a good cooperation during the light propagation process, avoid the imbalance of aberration correction caused by too large a thickness difference, and contribute to improving the imaging quality of the optical system 100.

[0073] In some embodiments, the optical system 100 satisfies the relation 1 ≤ CT1 / CT4 < 1.25, where CT1 is the thickness of the first lens L1 on the optical axis, and CT4 is the thickness of the fourth lens L4 on the optical axis. By reasonably configuring the thickness ratio of the first lens L1 and the fourth lens L4, the thickness of the first lens L1 and the fourth lens L4 can be maintained in a moderate relationship. While ensuring that the fourth lens L4 has sufficient negative refractive power to balance the system aberration, it is possible to avoid the adverse impact of its excessive thickness on the miniaturization design of the optical system 100.

[0074] In some embodiments, the optical system 100 satisfies the relation 1.01 < CT1 / AT12 < 1.13, where CT1 is the thickness of the first lens L1 on the optical axis, and AT12 is the spacing distance on the optical axis between the first lens L1 and the second lens L2. By controlling the ratio of the thickness of the first lens L1 to the spacing distance between the first lens L1 and the second lens L2 within this range, it is possible to ensure that the light enters the second lens L2 at an appropriate angle after passing through the first lens L1, avoid the light divergence caused by too large a spacing or the aberration superposition caused by too small a spacing, and thereby optimize the light transition effect between the lenses.

[0075] In some embodiments, the optical system 100 satisfies the relation 0.98 < AT23 / CT1 < 1.12, where CT1 is the thickness of the first lens L1 on the optical axis, and AT23 is the distance between the second lens L2 and the third lens L3 on the optical axis. By reasonably setting the ratio of the distance between the second lens L2 and the third lens L3 to the thickness of the first lens L1, it helps to provide sufficient adjustment space for light propagation while ensuring the compact structure of the optical system 100, and further improves the flexibility of aberration correction.

[0076] In some embodiments, the optical system 100 satisfies the relation 0.68 < CT1 / AT34 < 2.2, where CT1 is the thickness of the first lens L1 on the optical axis, and AT34 is the distance between the third lens L3 and the fourth lens L4 on the optical axis. By controlling the ratio of the thickness of the first lens L1 to the distance between the third lens L3 and the fourth lens L4, it is possible to balance the propagation path of light in the rear part of the lens group, ensure that the fourth lens L4 can effectively correct the light beam, and avoid an increase in the total optical length or a decrease in the imaging quality caused by an inappropriate distance.

[0077] In some embodiments, the optical system 100 satisfies the relation 1.62 < SD8 / SD6 < 1.84, where SD8 is half of the maximum effective aperture of the image side S8 of the fourth lens L4, and SD6 is half of the maximum effective aperture of the image side S6 of the third lens L3. By reasonably controlling the ratio of the maximum effective apertures of the image side S8 of the fourth lens L4 to the image side S6 of the third lens L3, it can ensure that light enters the fourth lens L4 at an appropriate angle after passing through the third lens L3, avoiding edge light loss or uneven image plane illumination caused by too large aperture differences, thereby improving the imaging quality of the optical system 100.

[0078] In some embodiments, the optical system 100 satisfies the relation 2.67 < SD8 / SD4 < 2.88, where SD4 is half of the maximum effective aperture of the image side S4 of the second lens L2, and SD8 is half of the maximum effective aperture of the image side S8 of the fourth lens L4. By reasonably controlling the ratio of the maximum effective apertures of the image side S8 of the fourth lens L4 to the image side S4 of the second lens L2, it helps to balance the aperture relationship between the image side S4 of the second lens L2 and the image side S8 of the fourth lens L4, causing the light to gradually converge during propagation and reducing the energy loss of the light beam at the lens edge.

[0079] In some embodiments, the optical system 100 satisfies the relation 3.08 < SD8 / SD2 < 4.1, where SD8 is half of the maximum effective aperture of the image side S8 of the fourth lens L4, and SD2 is half of the maximum effective aperture of the image side S2 of the first lens L1. By controlling the ratio of the maximum effective apertures of the image side S8 of the fourth lens L4 and the image side S2 of the first lens L1, the beam convergence ability of the optical system 100 can be effectively adjusted, ensuring that the light rays at the edge of the imaging surface can be evenly distributed and improving the imaging quality at a large viewing angle.

[0080] In some embodiments, the optical system 100 satisfies the relation 2.96 < SD8 / SD1 < 4.63, where SD8 is half of the maximum effective aperture of the image side S8 of the fourth lens L4, and SD1 is half of the maximum effective aperture of the object side S1 of the first lens L1. By reasonably controlling the ratio of the maximum effective apertures of the image side S8 of the fourth lens L4 and the object side S1 of the first lens L1, the aperture sizes of the object side S1 of the first lens L1 and the image side S8 of the fourth lens L4 can be reasonably matched. While ensuring that the first lens L1 has sufficient light collection ability, the fourth lens L4 can effectively converge the light beam, avoiding an increase in aberration at the edge of the imaging surface caused by an overly wide light beam, thus taking into account the requirements of a large viewing angle and high imaging quality.

[0081] In some embodiments, the optical system 100 satisfies the relation 4.09 < IMGH / SD1 < 6.62, where IMGH is half of the image height corresponding to the maximum viewing angle of the optical system 100, and SD1 is half of the maximum effective aperture of the object side S1 of the first lens L1. By reasonably setting the ratio of the half image height to half of the maximum effective aperture of the object side S1 of the first lens L1, while ensuring that the optical system 100 has the imaging ability at a large viewing angle, it is possible to avoid an increase in the volume and weight of the optical system 100 caused by an overly large aperture of the first lens L1, thus optimizing the miniaturized design of the optical system 100 on the basis of expanding the environmental perception range.

[0082] In some embodiments, the optical system 100 satisfies the relation 1.38 < IMGH / SD8 < 1.46, where IMGH is half of the image height corresponding to the maximum viewing angle of the optical system 100, and SD8 is half of the maximum effective aperture of the image side S8 of the fourth lens L4. By reasonably configuring the ratio of the half image height to half of the maximum effective aperture of the image side S8 of the fourth lens L4 within an appropriate range, it not only ensures that the imaging surface has sufficient size to present a clear and complete image, but also avoids the optical system 100 being structurally bloated due to an overly large aperture of the image side S8 of the fourth lens L4, which helps to achieve the balance between the thinness and lightness of the optical system 100 and high imaging quality.

[0083] In some embodiments, the optical system 100 satisfies the relationship 12% < RI < 27%, where RI is the relative illumination of the optical system 100 at a field of view of 1.0 when the radius of the imaging circle on the imaging surface 101 of the optical system 100 is 2.12 mm. By reasonably setting the relative illumination of the optical system 100, it is possible to ensure that the brightness of the edge area of ​​the imaging surface 101 is consistent with that of the central area, and to avoid obvious vignetting.

[0084] In some embodiments, the optical system 100 satisfies the relationship 36deg < Chief < 41deg, where Chief is the exit angle of the principal ray corresponding to the maximum field of view of the optical system 100 when the radius of the imaging circle on the imaging surface 101 of the optical system 100 is 2.12mm. By reasonably setting the exit angle of the principal ray, the photosensitive characteristics of the imaging surface 101 can be matched to ensure that the light enters the imaging surface 101 at a suitable angle, thereby improving the overall brightness and color reproduction of the image.

[0085] Example 1 Figure 1 This is a schematic diagram of the structure of the optical system disclosed in Embodiment 1 of this application. The optical system 100 includes an aperture stop 102, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4 and a filter 110 arranged sequentially along the optical axis from the object side to the image side.

[0086] Among them, the first lens L1 has positive refractive power, the second lens L2 has positive refractive power, the third lens L3 has positive refractive power, and the fourth lens L4 has negative refractive power.

[0087] The first lens L1, the second lens L2, the third lens L3, and the fourth lens L4 are all made of plastic.

[0088] Among them, the object-side surface S1 of the first lens L1 is convex near the optical axis, and the image-side surface S2 of the first lens L1 is concave near the optical axis; 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; the object-side surface S5 of the third lens L3 is concave near the optical axis, and the image-side surface S6 of the third lens L3 is convex near the optical axis; 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.

[0089] In this embodiment, when the imaging circle on the imaging surface 101 of the optical system 100 has a radius of 2.12 mm, the relative illumination RI of the optical system 100 in the 1.0 field of view is ≥26.5%, and the exit angle Chief of the principal ray corresponding to the maximum field of view is 36.992deg.

[0090] In this embodiment, the effective focal length parameter f, the aperture number FNO of the optical system 100, the maximum field of view FOV of the optical system 100, the total optical length TTL of the optical system, half the image height IMGH corresponding to the maximum field of view of the optical system 100, and other parameters of the optical system 100 are given in Table 1 below.

[0091] In this system, the elements along the optical axis of the optical system 100, from the object side to the image side, are arranged sequentially according to the order of the elements in Table 1 from top to bottom. Within the same lens, the surface with the smaller face number is the object-side surface, and the surface with the larger face number is the image-side surface. 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 aperture 102 in the "Thickness" parameter column represents the distance on the optical axis from the aperture 102 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 S1 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 aperture 102 is set on the image side of the vertex of the next surface. If the thickness of the aperture 102 is positive, the aperture 102 is on the object side of the vertex of the next surface. It can be understood that the units of Y radius, thickness, and focal length in Table 1 are all mm. Moreover, the refractive index, Abbe number, etc. in Table 1 are all obtained at a reference wavelength of 587.6 nm, and the focal length is obtained at a reference wavelength of 940 nm.

[0092] Table 1

[0093] In Example 1, the object-side surface S1 and image-side surface S2 of the first lens L1, the object-side surface S3 and image-side surface S4 of the second lens L2, the object-side surface S5 and image-side surface S6 of the third lens L3, and the object-side surface S7 and image-side surface S8 of the fourth lens L4 are all aspherical. The surface shape x of each aspherical lens can be limited by, but is not limited to, the following aspherical formula: ; Where x is the distance vector from the vertex of the aspherical surface at a height 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 above); K is the conic coefficient; Ai is the i-th order correction coefficient of the aspherical surface. Table 2 below gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, A20, A22, A24, A26, A28, and A30 for each lens aspherical surface.

[0094] Table 2

[0095] Figure 2 These are the spherical aberration diagram (mm), astigmatism diagram (mm), and distortion diagram (%) of the optical system disclosed in Embodiment 1 of this application. Figure 2 Figure (A) shows the spherical aberration diagrams of optical system 100 at wavelengths of 960 nm, 940 nm, and 920 nm. The horizontal axis along the X-axis represents the focal shift in mm, and the vertical axis along the Y-axis represents the normalized field of view. Figure 2 As can be seen from (A) in Example 1, the spherical aberration value of the optical system 100 is better, indicating that the imaging quality of the optical system 100 in this example is better.

[0096] Figure 2 (B) in the figure shows the astigmatism of the optical system 100 in Example 1 at a wavelength of 940 nm. The horizontal axis along the X-axis represents the focal shift in mm, and the vertical axis along the Y-axis represents the image height in mm. In the astigmatism diagram, T represents the curvature of the imaging surface 101 in the meridional direction, and S represents the curvature of the imaging surface 101 in the sagittal direction. Figure 2 As can be seen from (B) in the figure, at this wavelength, the field curvature of the optical system 100 is small, and the field curvature and astigmatism of each field of view are well corrected. The center and edge of the field of view have clear imaging, that is, the astigmatism of the optical system 100 is well compensated.

[0097] Figure 2 (C) in the figure represents the distortion diagram of the optical system 100 in Example 1 at a wavelength of 940 nm. The horizontal axis along the X-axis represents distortion, and the vertical axis along the Y-axis represents image height, in mm. Figure 2 As can be seen from (C), at this wavelength, the image distortion caused by the main beam is small, and the distortion of the optical system 100 is well corrected.

[0098] Example 2 Figure 3 This is a schematic diagram of the optical system disclosed in Embodiment 2 of this application.

[0099] For the information regarding the surface numbers and materials of each lens, as well as the correspondence between the object side and image side of each lens in this embodiment, please refer to the aforementioned Embodiment 1, which will not be repeated here.

[0100] In this embodiment, when the imaging circle on the imaging surface 101 of the optical system 100 has a radius of 2.12 mm, the relative illumination RI of the optical system 100 in the 1.0 field of view is ≥19%, and the exit angle Chief of the principal ray corresponding to the maximum field of view is 36.837deg.

[0101] In this embodiment, the effective focal length parameter f, the aperture number FNO, the maximum field of view (FOV), the total optical length (TTL), the half image height (IMGH) corresponding to the maximum field of view, and other parameters of the optical system 100 are given in Table 3 below. The definitions of each parameter can be derived from the descriptions of the foregoing embodiments and will not be repeated here. Furthermore, the refractive index, Abbe number, etc., in Table 3 are obtained at a reference wavelength of 587.6 nm, and the focal length is obtained at a reference wavelength of 940 nm.

[0102] Table 3

[0103] Table 4 provides the higher-order coefficients that can be used for each aspherical mirror in Example 2, wherein each aspherical surface shape can be defined by the formula given in Example 1.

[0104] Table 4

[0105] Please see Figure 4 ,Depend on Figure 4 As can be seen from (A) the spherical aberration diagram, (B) the ray astigmatism diagram, and (C) the distortion diagram, the spherical aberration, astigmatism, and distortion of the optical system 100 are well controlled, thus the optical system 100 of this embodiment possesses good imaging quality. Furthermore, regarding... Figure 4 (A) Figure 4 (B) and Figure 4 The wavelengths corresponding to the curves in (C) can be found in Example 1. Figure 2 (A) Figure 2 (B) Figure 2 The content described in (C) will not be repeated here.

[0106] Example 3 Figure 5 This is a schematic diagram of the optical system disclosed in Embodiment 3 of this application.

[0107] For the information regarding the surface numbers and materials of each lens, as well as the correspondence between the object side and image side of each lens in this embodiment, please refer to the aforementioned Embodiment 1, which will not be repeated here.

[0108] In this embodiment, when the imaging circle on the imaging surface of the optical system has a radius of 2.12 mm, the relative illumination RI of the optical system at a field of view of 1.0 is ≥12.3%, and the exit angle of the principal ray corresponding to the maximum field of view is 38.934 deg.

[0109] In this embodiment, the effective focal length parameter f, the aperture number FNO, the maximum field of view (FOV), the total optical length (TTL), the image height (IMGH) corresponding to the maximum field of view, and other parameters of the optical system 100 are given in Table 5 below. The definitions of each parameter can be derived from the descriptions of the preceding embodiments and will not be repeated here. Furthermore, the refractive index, Abbe number, etc., in Table 5 are obtained at a reference wavelength of 587.6 nm, and the focal length is obtained at a reference wavelength of 940 nm.

[0110] Table 5

[0111] Table 6 provides the higher-order coefficients that can be used for each aspherical mirror in Example 3, wherein each aspherical surface shape can be defined by the formula given in Example 1.

[0112] Table 6

[0113] Please see Figure 6 ,Depend on Figure 6 As can be seen from (A) the spherical aberration diagram, (B) the ray astigmatism diagram, and (C) the distortion diagram, the spherical aberration, astigmatism, and distortion of the optical system 100 are well controlled, thus the optical system 100 of this embodiment possesses good imaging quality. Furthermore, regarding... Figure 6 (A) Figure 6 (B) and Figure 6 The wavelengths corresponding to the curves in (C) can be found in Example 1. Figure 2 (A) Figure 2 (B) Figure 2 The content described in (C) will not be repeated here.

[0114] Example 4 Figure 7 This is a schematic diagram of the optical system disclosed in Embodiment 4 of this application.

[0115] In this embodiment, except that the image-side surface S4 of the second lens L2 is convex near the optical axis, the surface numbers and materials of the other lenses, as well as the correspondence between the object-side surface and the image-side surface of each lens, are as described in the aforementioned embodiment 1, and will not be repeated here.

[0116] In this embodiment, when the imaging circle on the imaging surface 101 of the optical system 100 has a radius of 2.12 mm, the relative illumination RI of the optical system 100 in the 1.0 field of view is ≥13.6%, and the exit angle of the principal ray corresponding to the maximum field of view is 39.419 deg.

[0117] In this embodiment, the effective focal length parameter f, the aperture number FNO, the maximum field of view (FOV), the total optical length (TTL), the half image height (IMGH) corresponding to the maximum field of view, and other 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 aforementioned examples and will not be repeated here. Furthermore, the refractive index, Abbe number, etc., in Table 7 are obtained at a reference wavelength of 587.6 nm, and the focal length is obtained at a reference wavelength of 940 nm.

[0118] Table 7

[0119] Table 8 gives the higher-order coefficients that can be used for each aspherical mirror in Example 4, wherein each aspherical surface shape can be defined by the formula given in Example 1.

[0120] Table 8

[0121] Please see Figure 8 ,Depend on Figure 8 As can be seen from (A) the spherical aberration diagram, (B) the ray astigmatism diagram, and (C) the distortion diagram, the spherical aberration, astigmatism, and distortion of the optical system 100 are well controlled, thus the optical system 100 of this embodiment possesses good imaging quality. Furthermore, regarding... Figure 8 (A) Figure 8 (B) and Figure 8 The wavelengths corresponding to the curves in (C) can be found in Example 1. Figure 2 (A) Figure 2 (B) Figure 2 The content described in (C) will not be repeated here.

[0122] Example 5 Figure 9 This is a schematic diagram of the optical system disclosed in Embodiment 5 of this application.

[0123] In this embodiment, except that the image-side surface S4 of the second lens L2 is convex near the optical axis, the surface numbers and materials of each lens, as well as the correspondence between the object-side surface and the image-side surface of each lens, are as described in the aforementioned embodiment 1, and will not be repeated here.

[0124] In this embodiment, when the imaging circle on the imaging surface 101 of the optical system 100 has a radius of 2.12 mm, the relative illumination RI of the optical system 100 in the 1.0 field of view is ≥12.1%, and the exit angle of the principal ray corresponding to the maximum field of view is 40.691deg.

[0125] In this embodiment, the effective focal length parameter f, the aperture number FNO, the maximum field of view (FOV), the total optical length (TTL), the image height (IMGH) corresponding to the maximum field of view, and other parameters of the optical system 100 are given in Table 9 below. The definitions of each parameter can be derived from the descriptions of the preceding embodiments and will not be repeated here. Furthermore, the refractive index, Abbe number, etc., in Table 9 are obtained at a reference wavelength of 587.6 nm, and the focal length is obtained at a reference wavelength of 940 nm.

[0126] Table 9

[0127] Table 10 gives the higher-order coefficients that can be used for each aspherical mirror in Example 5, wherein each aspherical surface shape can be defined by the formula given in Example 1.

[0128] Table 10

[0129] Please see Figure 10 ,Depend on Figure 10 As can be seen from (A) the spherical aberration diagram, (B) the ray astigmatism diagram, and (C) the distortion diagram, the spherical aberration, astigmatism, and distortion of the optical system 100 are well controlled, thus the optical system 100 of this embodiment possesses good imaging quality. Furthermore, regarding... Figure 10 (A) Figure 10 (B) and Figure 10 The wavelengths corresponding to the curves in (C) can be found in Example 1. Figure 2 (A) Figure 2 (B) Figure 2 The content described in (C) will not be repeated here.

[0130] Please refer to Table 11, which is a summary of the ratios of the various relationships in Embodiments 1 to 5 of this application.

[0131] Table 11

[0132] Please see Figure 11This application also discloses a camera module 200, which includes an image sensor 201 and an optical system 100 as described in any of the embodiments 1 to 5 above. The image sensor 201 is disposed on the image side of the optical system 100. Specifically, the photosensitive surface of the image sensor 201 is located on the imaging surface 101 of the optical system 100, and the light rays of an object incident on the photosensitive surface through the lens can be converted into electrical signals of the image. The image sensor 201 can be a complementary metal-oxide-semiconductor (CMOS) or a charge-coupled device (CCD). The camera module 200 can be an imaging module integrated on a terminal device 300 or a separate lens. 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, that is, it can perform infrared imaging while satisfying the requirements of large aperture, high imaging quality, miniaturized optical system design, and stable imaging in low-light environments. Since the above-mentioned technical effects have been described in detail in the embodiments of optical system 100, they will not be repeated here.

[0133] Please see Figure 12 This application also discloses a terminal device 300, which includes a housing 301 and the aforementioned camera module 200, with the camera module 200 disposed on the housing 301. The terminal device 300 may include, but is not limited to, mobile phones, tablets, laptops, smartwatches, in-vehicle devices, drones, and monitors. Taking a mobile phone as an example, the housing 301 can be a mobile phone casing, and the camera module 200 can be disposed on the mobile phone body.

[0134] It is understood that the terminal device 300 with the aforementioned camera module 200 also possesses all the technical effects of the aforementioned optical system 100. That is, the terminal device 300 is able to perform infrared imaging while simultaneously achieving large aperture, high imaging quality, miniaturized optical system design, and stable imaging in low-light environments. Since the aforementioned technical effects have been described in detail in the embodiments of the optical system 100, they will not be repeated here.

[0135] The optical system, camera module, and terminal 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 descriptions of the embodiments above are only for the purpose of helping to understand the optical system, camera module, and terminal 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 a total of four lenses with refractive power, including a first lens, a second lens, a third lens, and a fourth lens arranged in sequence 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 near the optical axis, and the image side surface of the first lens is concave near the optical axis; The second lens has positive refractive power. The object side surface of the second lens is convex near the optical axis; The third lens has positive refractive power. The object side surface of the third lens is concave near the optical axis, and the image side surface of the third lens is convex near the optical axis; The fourth lens has negative refractive power. The object side surface of the fourth lens is convex near the optical axis, and the image side surface of the fourth lens is concave near the optical axis; The optical system satisfies the relation: 84deg < FOV < 103deg and 2.24 ≤ FNO ≤ 2.71; where, FOV is the maximum field angle 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 relation: 0.99 < TTL / IMGH < 1.19; where, TTL is the distance from the object side surface of the first lens to the imaging surface of the optical system in the direction of the optical axis, and IMGH is half of the image height corresponding to the maximum field angle of the optical system.

3. The optical system according to claim 1, characterized in that, The optical system satisfies the following relation: 1.2 < f1 / f < 1.6, and / or, 8.4 < f2 / f < 164, and / or, 1.5 < f3 / f < 2.36, and / or, -2.3 < f4 / f < -1; where, f is the focal length of the optical system, 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, and f4 is the focal length of the fourth lens.

4. The optical system according to claim 1, characterized in that, The optical system satisfies the following relation: 2.04 < f / R1 < 2.85, and / or, 1 < f / R2 < 1.48, and / or, 1.41 < R3 / f < 112.2, and / or, 1.6 < |R4| / f < 20.5, and / or, -1.74 < R5 / f < -1.25, and / or, -1.92 < f / R6 ≤ -1.36, and / or, 2.2 < f / R7 < 3.7, and / or, 4.3 < f / R8 < 5.43; where, f is the focal length of the optical system, R1 is the curvature radius of the object side surface of the first lens at the optical axis, R2 is the curvature radius of the image side surface of the first lens at the optical axis, R3 is the curvature radius of the object side surface of the second lens at the optical axis, R4 is the curvature radius of the image side surface of the second lens at the optical axis, R5 is the curvature radius of the object side surface of the third lens at the optical axis, R6 is the curvature radius of the image side surface of the third lens at the optical axis, R7 is the curvature radius of the object side surface of the fourth lens at the optical axis, and R8 is the curvature radius of the image side surface of the fourth lens at the optical axis.

5. The optical system according to claim 1, characterized in that, The optical system satisfies the following relation: 1.08 < CT1 / CT2 < 1.62, and / or, 0.89 < CT1 / CT3 < 1.25, and / or, 1 ≤ CT1 / CT4 < 1.25; Where, 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, and CT4 is the thickness of the fourth lens on the optical axis.

6. The optical system according to claim 1, characterized in that, The optical system satisfies the following relationships: 1.01 < CT1 / AT12 < 1.13, and / or, 0.98 < AT23 / CT1 < 1.12, and / or, 0.68 < CT1 / AT34 < 2.2; Where, CT1 is the thickness of the first lens on the optical axis, AT12 is the axial spacing distance between the first lens and the second lens, AT23 is the axial spacing distance between the second lens and the third lens, and AT34 is the axial spacing distance between the third lens and the fourth lens.

7. The optical system according to claim 1, characterized in that, The optical system satisfies the following relationships: 1.62 < SD8 / SD6 < 1.84, and / or, 2.67 < SD8 / SD4 < 2.88, and / or, 3.08 < SD8 / SD2 < 4.1, and / or, 2.96 < SD8 / SD1 < 4.63; Where, SD1 is half of the maximum effective aperture of the object side of the first lens, SD2 is half of the maximum effective aperture of the image side of the first lens, SD4 is half of the maximum effective aperture of the image side of the second lens, SD6 is half of the maximum effective aperture of the image side of the third lens, and SD8 is half of the maximum effective aperture of the image side of the fourth lens.

8. The optical system according to claim 1, characterized in that, The optical system satisfies the following relationships: 4.09 < IMGH / SD1 < 6.62, and / or, 1.38 < IMGH / SD8 < 1.46; Where, IMGH is half of the image height corresponding to the maximum field angle of the optical system, SD1 is half of the maximum effective aperture of the object side of the first lens, and SD8 is half of the maximum effective aperture of the image side of the fourth lens.

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

10. A terminal device, characterized in that, An imaging module including the imaging module according to claim 9.

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