Optical system, lens module and electronic device

Abstract

An optical system, a lens module and an electronic device, the optical system has five pieces of lenses with refractive power, sequentially includes from the object side to the image side along the optical axis direction: the first lens with negative refractive power, the object side surface is concave at the near optical axis, the image side surface is concave at the near optical axis; the second lens with positive refractive power, the object side surface is convex at the near optical axis, the image side surface is convex at the near optical axis; the third lens with positive refractive power, the object side surface is convex at the near optical axis, the image side surface is concave at the near optical axis; the fourth lens with positive refractive power; the fifth lens with negative refractive power; the optical system satisfies the relationship: 135°<FOV<152°; wherein, FOV is the maximum field of view angle of the optical system. The optical system can meet the characteristics of ultra-wide angle.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical imaging, and particularly relates to an optical system, a lens module, and an electronic device. Background Art

[0002] With the proposal of the metaverse concept, VR (Virtual Reality) experiences have enriched our lives, enabling people to experience virtual fairy tales, vast cosmic spaces, and dynamic game environments, and feeling an unprecedented visual feast. How to make the visual experience more vivid, the optical system has become the core component of the visual experience. Among them, how to enable the optical system to have a larger shooting range and a clearer imaging effect has become a key issue. Summary of the Invention

[0003] The object of the present invention is to provide an optical system, a lens module, and an electronic device, and the optical system can meet the characteristics of ultra-wide angle and large light flux.

[0004] To achieve the object of the present invention, the present invention provides the following technical solutions:

[0005] In a first aspect, the present invention provides an optical system, the number of lenses with refractive power is five, and sequentially includes, along the optical axis direction from the object side to the image side: a first lens with negative refractive power, the object side surface is concave at the near optical axis, and the image side surface is concave at the near optical axis; a second lens with positive refractive power, the object side surface is convex at the near optical axis, and the image side surface is convex at the near optical axis; a third lens with refractive power, the object side surface is convex at the near optical axis, and the image side surface is concave at the near optical axis; a fourth lens with positive refractive power, the object side surface is convex at the near optical axis, and the image side surface is convex at the near optical axis; a fifth lens with negative refractive power, the object side surface is convex at the near optical axis, and the image side surface is concave at the near optical axis; the optical system satisfies the relational expression: 135° < FOV < 152°; where FOV is the maximum field angle of the optical system.

[0006] This application designs a first lens with negative refractive power, which facilitates the entry of large-angle light into the optical system, achieving a large field of view. The concave object-side surface further enhances this large field of view, while the concave image-side surface ensures that light rays at various angles enter the subsequent optical system at appropriate angles, preventing excessive incident angles on the image-side surface that could cause internal reflections and ghosting, thus affecting image quality. The second lens has positive refractive power. Combined with its convex-concave shape near the optical axis, the second lens helps balance the aberrations generated by the first lens, thereby improving the image quality of the optical system. Furthermore, the negative refractive power of the first lens and the positive refractive power of the second lens can mutually cancel out each other's aberrations. The third lens, also with refractive power, ensures a balanced distribution of refractive power in the optical system, preventing excessive refractive power pressure on the front lenses (i.e., the first and second lenses), thus avoiding uncorrectable aberrations between lenses. The fourth lens, with positive refractive power, has a convex object-side surface near the optical axis, which helps converge light rays and reduce distortion. Its convex image-side surface facilitates cooperation with the object-side surface of the fifth lens, allowing light rays to pass smoothly through the fifth lens to reach the image plane. The fifth lens has negative refractive power, and its object-side and image-side surfaces are convex and concave near the optical axis, respectively. This reduces the tolerance sensitivity of the optical system and further balances the aberrations generated by the front lens group (first to fourth lenses), promoting aberration balance in the optical system and thus improving the imaging quality of the optical system.

[0007] When the above relationship is satisfied, the maximum field of view of the optical system is controlled within a reasonable range, enabling the optical system to have ultra-wide-angle shooting characteristics.

[0008] Secondly, the present invention also provides a lens module, which includes an optical system according to any embodiment of the first aspect and a photosensitive chip, wherein the photosensitive chip is disposed on the image side of the optical system. By incorporating the optical system provided by the present invention into the lens module, and by rationally designing the surface shape and refractive power of each lens in the optical system and fixing the total optical length, the lens module can possess ultra-wide-angle characteristics.

[0009] Thirdly, the present invention also provides an electronic device, which includes a housing and a lens module as described in the second aspect, the lens module being disposed within the housing. By incorporating the lens module provided by the present invention into the electronic device, the electronic device can possess ultra-wide-angle characteristics, thereby achieving a larger shooting range and clearer image quality. Attached Figure Description

[0010] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0011] Figure 1 This is a schematic diagram of the optical system of the first embodiment;

[0012] Figure 2 An aberration diagram of the optical system of the first embodiment;

[0013] Figure 3 This is a schematic diagram of the optical system in the second embodiment;

[0014] Figure 4 Aberration diagram of the optical system in the second embodiment;

[0015] Figure 5 This is a schematic diagram of the optical system in the third embodiment;

[0016] Figure 6 Aberration diagram of the optical system in the third embodiment;

[0017] Figure 7 This is a schematic diagram of the optical system in the fourth embodiment;

[0018] Figure 8 Aberration diagram of the optical system in the fourth embodiment;

[0019] Figure 9 This is a schematic diagram of the optical system in the fifth embodiment;

[0020] Figure 10 Aberration diagram of the optical system in the fifth embodiment;

[0021] Figure 11 This is a schematic diagram of the optical system in the sixth embodiment;

[0022] Figure 12 Aberration diagram of the optical system in the sixth embodiment;

[0023] Figure 13 This is a schematic diagram of a lens module provided in an embodiment of the present invention;

[0024] Figure 14 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present invention. Detailed Implementation

[0025] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0026] In a first aspect, the present invention provides an optical system. The number of lenses with refractive power is five. Along the optical axis direction from the object side to the image side, it sequentially includes: a first lens with negative refractive power, the object side surface is concave near the optical axis, and the image side surface is concave near the optical axis; a second lens with positive refractive power, the object side surface is convex near the optical axis, and the image side surface is convex near the optical axis; a third lens with refractive power, the object side surface is convex near the optical axis, and the image side surface is concave near the optical axis; a fourth lens with positive refractive power, the object side surface is convex near the optical axis, and the image side surface is convex near the optical axis; a fifth lens with negative refractive power, the object side surface is convex near the optical axis, and the image side surface is concave near the optical axis; the optical system satisfies the relational expression: 135° < FOV < 152°; where FOV is the maximum field angle of the optical system. Specifically, the value of FOV can be: 135.54, 138.55, 139.52, 140.35, 141.39, 142.64, 143.64, 144.47, 150.87, 151.73.

[0027] By designing the first lens with negative refractive power, this application facilitates the entry of light at large angles into the optical system, achieving the characteristic of a large field of view angle. Moreover, by using a concave surface on the object side, the characteristic of a large field of view can be realized, and a concave surface on the image side enables light at various angles to enter the subsequent optical system at appropriate angles, avoiding excessive incident angles of light on the image side that may cause internal reflection in the lens and form ghost images, thus affecting the imaging quality. The second lens has positive refractive power, and in combination with the convex-concave surface shape of the second lens near the optical axis, it helps to balance the aberrations generated by the first lens, thereby facilitating the improvement of the imaging quality of the optical system. Additionally, the combination of the first lens with negative refractive power and the second lens with positive refractive power can cancel out the aberrations generated by each other. The third lens with refractive power can evenly distribute the refractive power of the optical system, avoiding excessive refractive power pressure on the front lenses (i.e., the first lens and the second lens), and thus preventing the generation of difficult-to-correct aberrations between the lenses. The fourth lens with positive refractive power has a convex surface near the optical axis on the object side, which is conducive to converging light and reducing distortion, and a convex surface on the image side is conducive to cooperating with the object side of the fifth lens, enabling light to pass through the fifth lens smoothly to reach the imaging surface. The fifth lens has negative refractive power, and the object side and the image side of the fifth lens are convex and concave respectively near the optical axis, which can reduce the tolerance sensitivity of the optical system and further balance the aberrations generated by the front lens group (the first lens to the fourth lens), promoting the aberration balance of the optical system, and thus improving the imaging quality of the optical system.

[0028] When the above relationship is satisfied, the maximum field of view angle of the optical system is controlled within a reasonable range, enabling the optical system to have the characteristics of ultra-wide-angle shooting.

[0029] In one implementation, 0.2 < GL / Imgh < 0.3; where GL is the radius size at the effective aperture of the aperture stop in the optical system, and Imgh is half of the image height corresponding to the maximum field of view angle of the optical system. Specifically, the value of GL / Imgh can be 0.21, 0.22, 0.23, 0.24, 0.25, 0.26, 0.27, 0.28, 0.29. Since the aperture size of the aperture stop in the optical system determines the light passing amount of the entire optical system, and the size of the photosensitive surface determines the picture clarity and pixel size of the entire optical system. Therefore, when the above relationship is satisfied, both the effective aperture of the aperture stop and the image height can be reasonably configured to ensure that the optical system has sufficient light passing amount, thereby ensuring the clarity of the captured image. When exceeding the upper limit of this relationship, it will cause excessive light passing amount in the optical system and too high light brightness, resulting in overexposure and affecting the quality of the captured image; when below the lower limit of this relationship, the light passing amount in the optical system is too small and the light is insufficient, causing a decrease in the clarity of the captured image.

[0030] In one embodiment, the optical system satisfies the relation: 0.9 < SD11 / SD52 < 1.25; where SD11 is half of the maximum effective aperture of the object side of the first lens, and SD52 is half of the maximum effective aperture of the image side of the fifth lens. Specifically, the value of SD11 / SD52 can be 0.93, 0.97, 1.01, 1.04, 1.08, 1.12, 1.15, 1.17, 1.20, 1.22. The maximum effective aperture of the object side of the first lens determines the amount of light entering the entire optical system; while the maximum effective aperture of the image side of the fifth lens corresponds to the height of the imaging surface and determines the resolution of the entire system. Therefore, when the above relation is satisfied, it can ensure sufficient light transmission and the corresponding image height to meet the high-definition shooting requirements; at the same time, satisfying the above relation can also ensure that the aperture sizes of the object side of the first lens and the image side of the fifth lens are close, which helps with miniaturization design and avoids wasting the assembly space of the optical system. When exceeding the upper limit of this relation, it will cause too much light to enter the optical system, making it more difficult for the optical system to correct aberrations, resulting in a decrease in image clarity, and the too large aperture of the first lens causes the optical system to not meet the miniaturization design; when lower than the lower limit of this relation, the image height cannot meet the requirements of the photosensitive chip, resulting in a decrease in the resolution of the optical system, and the too large aperture of the fifth lens causes the optical system to not meet the miniaturization design.

[0031] In one embodiment, the optical system satisfies the relation: 1.2 mm / rad < D11 / RAD < 1.8 mm / rad; where D11 is the maximum effective aperture of the object side of the first lens, and RAD is the radian value of the maximum field angle of the optical system. Specifically, the value of D11 / RAD can be: 1.22, 1.27, 1.33, 1.38, 1.44, 1.47, 1.54, 1.56, 1.73, 1.78. In the optical system provided in this application, the maximum effective aperture of the object side of the first lens determines the field angle size. Therefore, when the above relation is satisfied, the maximum effective aperture of the object side of the first lens and the radian value of the field angle of the optical system are reasonably configured, ensuring that a larger range of light can enter the optical system. When exceeding the upper limit of this relation, it will cause the field angle to be too small, and the imaging range of the captured image does not reach the shooting effect of a large field of view; when lower than the lower limit of this relation, the aperture of the object side of the first lens is too small while the field angle is too large, resulting in serious imaging distortion and the outer field of the captured image being distorted.

[0032] In one embodiment, the optical system satisfies the relation: 2 < ET5 / CT5 < 2.5; where ET5 is the edge thickness of the fifth lens and CT5 is the thickness of the fifth lens on the optical axis. Specifically, the value of ET5 / CT5 can be: 2.01, 2.06, 2.08, 2.14, 2.17, 2.20, 2.21, 2.25, 2.35, 2.48. When the above relation is satisfied, the fifth lens has its edge thickness and central thickness within a reasonable range, with a relatively small surface shape variation, which can effectively control the aberrations in the optical system. At the same time, it is also beneficial for processing in terms of technology and can improve the production yield. When exceeding the upper limit of this relation, the center of the fifth lens is too thick relative to the edge, resulting in excessive field curvature of the image plane; when lower than the lower limit of this relation, it will cause the center of the fifth lens to be too thin relative to the edge, making it impossible to meet the production processing requirements and ensure the forming yield.

[0033] In one embodiment, the optical system satisfies the relation: 0 < (|R31 - R32|) / (|R31 + R32|) < 0.35; where R31 is the curvature radius of the object side of the third lens on the optical axis and R32 is the curvature radius of the image side of the third lens on the optical axis. Specifically, the value of (|R31 - R32|) / (|R31 + R32|) can be: 0.01, 0.05, 0.08, 0.12, 0.16, 0.23, 0.26, 0.27, 0.32, 0.33. When the above relation is satisfied, the curvature radii of the object side and the image side of the third lens are relatively appropriate, which can reasonably correct the spherical aberration of the optical system, balance the optical path difference of the optical system, correct the field curvature, and at the same time reduce the sensitivity of the optical system and improve the assembly stability. When exceeding the upper limit of this relation, it will cause excessive field curvature of the optical system; when lower than the lower limit of this relation, it will cause an increase in the sensitivity of the optical system and reduce the production yield.

[0034] In one embodiment, the optical system satisfies the relation: 0.8 < ∑ET / ∑CT < 1.1; where ∑ET is the total edge thickness of all lenses in the optical system and ∑CT is the total thickness of all lenses in the optical system on the optical axis. Specifically, the value of ∑ET / ∑CT can be: 0.82, 0.85, 0.89, 0.92, 0.95, 0.99, 1.01, 1.02, 1.06, 1.08. When the above relation is satisfied, the total central thickness and the total edge thickness of all lenses in the optical system can be reasonably configured, which is beneficial for balancing the optical path difference between the central field and the edge field, thereby effectively improving the field curvature and reducing the distortion. When exceeding the upper limit of this relation, the optical path of the edge field will be greater than that of the central ray, resulting in excessive field curvature and causing the image of the outer field to be blurred; when lower than the lower limit of this relation, the optical path of the edge field will be less than that of the central ray, also resulting in excessive field curvature and causing the image of the outer field to be blurred.

[0035] In one embodiment, the optical system satisfies the relationship: 1.2 < (SD42 + SD52) / Imgh < 1.6; where SD42 is half the maximum effective aperture of the image-side surface of the fourth lens, and SD52 is half the maximum effective aperture of the image-side surface of the fifth lens. Specifically, the value of (SD42 + SD52) / Imgh can be: 1.21, 1.26, 1.33, 1.37, 1.38, 1.41, 1.42, 1.46, 1.52, 1.55, 1.58. When the above condition is satisfied, the maximum effective aperture of the image-side surface of the fourth lens, the maximum effective aperture of the image-side surface of the fifth lens, and the image height can be reasonably configured. When light passes through the fourth and fifth lenses and reaches the imaging plane, the transition can be smooth, which can be understood as the propagation of light being more stable. When the upper limit of this relationship is exceeded, the light passing through the fourth and fifth lenses will be refracted too much, making it difficult for the light to smoothly transition to the imaging surface. When the lower limit of this relationship is exceeded, the light will transition to the imaging surface at a large angle after passing through the fourth and fifth lenses, making it impossible for the image on the imaging surface to match the appropriate photosensitive chip, resulting in poor imaging effect.

[0036] In one embodiment, the optical system satisfies the relationship: 1mm < (ΣET*EPD) / f < 2mm; where ΣET is the sum of the edge thicknesses of all lenses in the optical system, EPD is the entrance pupil diameter of the optical system, and f is the effective focal length of the optical system. Specifically, the value of (ΣET*EPD) / f can be: 1.02, 1.15, 1.22, 1.40, 1.57, 1.60, 1.63, 1.76, 1.88, or 1.97. When the above condition is satisfied, the effective focal length and entrance pupil diameter of the optical system can be reasonably configured, which is beneficial for the optical system to introduce appropriate light transmission, resulting in a clearer image. At the same time, in conjunction with the sum of the edge thicknesses of all lenses, it is also possible to better correct field curvature while ensuring sufficient light transmission, resulting in a clear image with less distortion.

[0037] In one embodiment, the optical system satisfies the relationship: 0.5 < f1 / R11 < 1; where f1 is the focal length of the first lens, and R11 is the radius of curvature of the object side surface of the first lens at the optical axis. Specifically, the value of f1 / R11 can be: 0.51, 0.54, 0.57, 0.59, 0.63, 0.65, 0.69, 0.76, 0.84, 0.99. When the above relationship is satisfied, the adaptability between the radius of curvature of the object side surface of the first lens and the effective focal length of the first lens is relatively high, and a larger field of view range can be provided for the optical system. When exceeding the upper limit of this relationship, it will cause the radius of curvature of the object side surface of the first lens to be too large, increasing the processing difficulty of the process; when lower than the lower limit of this relationship, it will result in insufficient adaptability between the focal length and the lens surface radius, leading to an increase in the amount of astigmatism and a decline in the imaging performance of the optical system.

[0038] In one embodiment, the optical system satisfies the relationship: -3 < SAG51 / AT45 < -0.4; where SAG51 is the distance in the direction parallel to the optical axis from the intersection of the object side surface of the fifth lens and the optical axis to the maximum effective aperture of the object side surface of the fifth lens, and AT45 is the maximum air gap between the fourth lens and the fifth lens in the optical axis direction. Specifically, the value of SAG51 / AT45 can be: -2.96, -2.61, -2.34, -1.87, -1.42, -0.81, -0.65, -0.56, -0.53, -0.41. When the above relationship is satisfied, the ratio of the sagitta of the object side surface of the fifth lens to the maximum air gap between the fourth lens and the fifth lens is reasonably configured, which can improve the field curvature and avoid image edge distortion; at the same time, it can also provide sufficient tolerance space when arranging the lens barrel. When exceeding the upper limit of this relationship, it is not conducive to field curvature correction, resulting in edge image distortion, forming a distorted image, and causing a poor fit between the optical system and the lens barrel; when lower than the lower limit of this relationship, it will cause the object side surface of the fifth lens to be too curved, which is not conducive to the processing and forming of a single lens, and the assembly difficulty increases, which is not conducive to the improvement of the assembly process.

[0039] In one embodiment, the optical system satisfies the relationship: 0.8 < R41 / f < 5; where R41 is the radius of curvature of the object side of the fourth lens at the optical axis, and f is the effective focal length of the optical system. Specifically, the value of R41 / f can be: 0.82, 0.95, 1.03, 1.26, 1.24, 1.45, 2.07, 2.34, 3.79, 4.5, 4.95. When the above relationship is satisfied, by controlling the radius of curvature of the object side of the fourth lens and the effective focal length of the optical system within a reasonable range, it is possible to avoid excessive bending of the lens, reduce the processing difficulty, and is also conducive to controlling the field curvature of the optical system. When exceeding the upper limit of this relationship, the radius of curvature of the object side of the fourth lens at the optical axis is too large, while the effective focal length of the optical system is too small, which is not conducive to the assembly and manufacture of the optical system; when below the lower limit of this relationship, the radius of curvature of the object side of the fourth lens at the optical axis is too small, while the effective focal length of the optical system is too large, resulting in a reduction in the resolution of the optical system and affecting the imaging clarity.

[0040] In one embodiment, the optical system satisfies the relationship: 7 < SD11 / SAG11 < 19; where SD11 is half of the maximum effective aperture of the object side of the first lens, and SAG11 is the distance from the intersection of the object side of the first lens and the optical axis to the maximum effective aperture of the object side of the first lens in the direction parallel to the optical axis. Specifically, the value of SD11 / SAG11 can be: 7.25, 8.09, 9.53, 10.45, 11.65, 13.74, 13.95, 14.94, 16.41, 18.65. When the above relationship is satisfied, the semi-aperture of the object side of the first lens and the object side sagittal height can be reasonably configured, so as to effectively expand the field angle range, and at the same time ensure that the lens has good formability and assembly process yield. When exceeding the upper limit of this relationship, the lens aperture is too large and the sagittal height is too small, making it difficult to correct the aberration caused by large-angle light incidence; when below the lower limit of this relationship, it will cause the outer periphery of the lens to be too curved, which is not conducive to lens processing and forming and the improvement of the assembly process yield.

[0041] In a second aspect, the present invention further provides a lens module, which includes the optical system according to any one of the embodiments in the first aspect and a photosensitive chip, and the photosensitive chip is disposed on the image side of the optical system. By adding the optical system provided by the present invention to the lens module, through reasonable design of the surface shape and refractive power of each lens in the optical system and a fixed optical total length, the lens module can be made to have the characteristics of ultra-wide angle and large light transmission.

[0042] Thirdly, the present invention also provides an electronic device, which includes a housing and a lens module as described in the second aspect, the lens module being disposed within the housing. By incorporating the lens module provided by the present invention into the electronic device, the electronic device can possess the characteristics of ultra-wide-angle and high light transmission, thereby achieving a larger shooting range and clearer image quality.

[0043] First Embodiment

[0044] Please refer to Figure 1 and Figure 2 The optical system 10 of this embodiment comprises, from the object side to the image side, the following components in sequence: a first lens L1 with negative refractive power, its object side S1 being concave near the optical axis, and its image side S2 being concave near the optical axis; a second lens L2 with positive refractive power, its object side S3 being convex near the optical axis, and its image side S4 being convex near the optical axis; a third lens L3 with negative refractive power, its object side S5 being convex near the optical axis, and its image side S6 being concave near the optical axis; a fourth lens L4 with positive refractive power, its object side S7 being convex near the optical axis, and its image side S8 being convex near the optical axis; and a fifth lens L5 with negative refractive power, its object side S9 being convex near the optical axis, and its image side S10 being concave near the optical axis.

[0045] In addition, the optical system 10 also includes an aperture stop STO, an infrared filter IR, and an imaging surface IMG. In this embodiment, the aperture stop STO is positioned between the first lens L1 and the second lens L2 to control the amount of light entering the lens. In other embodiments, the aperture stop STO can also be positioned in front of the first lens L1, or between the second lens L2 and the third lens L3. The infrared filter IR can be an infrared cut-off filter, positioned between the fifth lens L5 and the imaging surface IMG. It includes an object-side surface S11 and an image-side surface S12. The infrared cut-off filter is used to filter out infrared light, so that the light entering the imaging surface IMG is visible light with a wavelength of 380nm-780nm. The infrared cut-off filter is made of glass and can be coated on the lens. Of course, in other embodiments, the filter IR can also be an infrared pass-through filter, used to filter visible light and allow only infrared light to pass through, which can be used for infrared imaging, etc. The first lens L1 to the fifth lens L5 are made of plastic. In other embodiments, the lens material can also be glass, or a glass-plastic hybrid, where some lenses are plastic and others are glass. The effective pixel area of ​​the photosensitive chip is located on the imaging surface IMG.

[0046] Table 1a shows the characteristics of the optical system 10 of this embodiment. The reference wavelength for the focal length of the lens is 555 nm, and the reference wavelength for the refractive index and Abbe number is 587.56 nm. The Y-radius in Table 1a is the radius of curvature of the object-side or image-side surface of the corresponding surface number at the optical axis 101. Surface numbers S1 and S2 are the object-side surface S1 and image-side surface S2 of the first lens L1, respectively. That is, in the same lens, the surface with the smaller surface number is the object-side surface, and the surface with the larger surface number is the image-side surface. The first value in the "thickness" parameter column of the first lens L1 is the thickness of the lens on the optical axis 101, and the second value is the distance from the image-side surface of the lens to the subsequent optical surface (the object-side surface or aperture surface of the subsequent lens) on the optical axis 101. The units for Y-radius, thickness, and focal length are all millimeters (mm).

[0047] Table 1a

[0048]

[0049] As shown in Table 1a, f is the effective focal length of the optical system 10, Fno is the aperture number of the optical system 10, FOV is the maximum field of view of the optical system 10, and TTL is the distance on the optical axis 101 from the object side surface S1 of the first lens L1 to the imaging surface IMG of the optical system 10.

[0050] In this embodiment, the object-side and image-side surfaces of the first lens L1 to the fifth lens L5 are both aspherical. In other embodiments, the object-side and image-side surfaces of the first lens L1 to the fifth lens L5 may also be spherical, or a combination of spherical and aspherical surfaces. For example, the object-side surface S1 of the first lens L1 may be spherical, and the image-side surface S2 may be aspherical. The surface shape x of the aspherical surface can be defined using, but is not limited to, the following aspherical formula:

[0051]

[0052] Where x is the distance from the corresponding point on the aspherical surface to the plane tangent to the vertex on the axis, h is the distance from the corresponding point on the aspherical surface to the optical axis 101, c is the curvature of the vertex of the aspherical surface, k is the conic coefficient, and Ai is the coefficient corresponding to the i-th higher-order term in the aspherical surface shape formula. Table 1b gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 of the aspherical mirrors S1 to S10 that can be used in the first embodiment.

[0053] Table 1b

[0054]

[0055]

[0056] Figure 2Figure (a) shows the longitudinal spherical aberration curves of the optical system of the first embodiment at wavelengths of 656.0000 nm, 610.000 nm, 555.0000 nm, 510.0000 nm, 470.0000 nm, and 435.0000 nm. The horizontal axis along the X-axis represents the focal point shift in mm, and the vertical axis along the Y-axis represents the normalized field of view. The longitudinal spherical aberration curves represent the deviation of the focal point after light of different wavelengths passes through the lenses of the optical system. Figure 2 As can be seen from (a), the spherical aberration value of the optical system in the first embodiment is better, indicating that the imaging quality of the optical system in this embodiment is better.

[0057] Figure 2 Figure (b) also shows an astigmatism curve of the optical system of the first embodiment at a wavelength of 555.0000 nm, where the horizontal axis along the X-axis represents the focal shift in mm, and the vertical axis along the Y-axis represents the half-image height in mm. In the astigmatism curve, T represents the curvature of the imaging plane IMG in the meridional direction, and S represents the curvature of the imaging plane IMG in the sagittal direction. Figure 2 As can be seen in (b), the astigmatism of the optical system is well compensated.

[0058] Figure 2 Figure (c) also shows a distortion curve of the optical system of the first embodiment at a wavelength of 555.0000 nm. The horizontal axis along the X-axis represents distortion, and the vertical axis along the Y-axis represents half-image height, in mm. The distortion curve represents the distortion magnitude corresponding to different field of view angles. Figure 2 As can be seen in (c), the distortion of the optical system is well corrected at a wavelength of 555.0000 nm.

[0059] Depend on Figure 2 As can be seen from (a), (b) and (c), the optical system of this embodiment has small aberrations, good imaging quality, and excellent imaging performance.

[0060] Second Embodiment

[0061] Please refer to Figure 3 and Figure 4 The structure of the optical system 10 in this embodiment is the same as that in the first embodiment, and can be referred to accordingly.

[0062] Table 2a shows the characteristics of the optical system 10 in this embodiment. The meanings of each parameter are the same as those in the first embodiment, and will not be repeated here.

[0063] Table 2a

[0064]

[0065] Table 2b shows the higher-order coefficients that can be used for each aspherical mirror in the second embodiment, wherein each aspherical surface shape can be defined by the formula given in the first embodiment.

[0066] Table 2b

[0067]

[0068]

[0069] Figure 4 The diagrams show the longitudinal spherical aberration, astigmatism, and distortion curves of the optical system according to the second embodiment. Figure 4 As can be seen from the aberration diagram, the longitudinal spherical aberration, field curvature, and distortion of the optical system are all well controlled, thus the optical system of this embodiment has good imaging quality.

[0070] Third Embodiment

[0071] Please refer to Figure 5 and Figure 6 The structure of the optical system 10 in this embodiment is the same as that in the first embodiment, and can be referred to accordingly.

[0072] Table 3a shows the characteristics of the optical system 10 in this embodiment. The meanings of each parameter are the same as those in the first embodiment, and will not be repeated here.

[0073] Table 3a

[0074]

[0075] Table 3b shows the higher-order coefficients that can be used for each aspherical mirror in the third embodiment, wherein each aspherical surface shape can be defined by the formula given in the first embodiment.

[0076] Table 3b

[0077]

[0078]

[0079] Figure 6 The diagram shows the longitudinal spherical aberration, astigmatism, and distortion curves of the optical system according to the third embodiment. Figure 6 As can be seen from the aberration diagram, the longitudinal spherical aberration, field curvature, and distortion of the optical system are all well controlled, thus the optical system of this embodiment has good imaging quality.

[0080] Fourth embodiment

[0081] Please refer to Figure 7 and Figure 8The structure of the optical system 10 in this embodiment is the same as that in the first embodiment, and can be referred to accordingly.

[0082] Table 4a shows the characteristics of the optical system 10 in this embodiment. The meanings of each parameter are the same as those in the first embodiment, and will not be repeated here.

[0083] Table 4a

[0084]

[0085]

[0086] Table 4b shows the higher-order coefficients that can be used for each aspherical mirror in the fourth embodiment, wherein each aspherical surface shape can be defined by the formula given in the first embodiment.

[0087] Table 4b

[0088]

[0089] Figure 8 The diagram shows the longitudinal spherical aberration, astigmatism, and distortion curves of the optical system according to the fourth embodiment. Figure 8 As can be seen from the aberration diagram, the longitudinal spherical aberration, field curvature, and distortion of the optical system are all well controlled, thus the optical system of this embodiment has good imaging quality.

[0090] Fifth Embodiment

[0091] Please refer to Figure 9 and Figure 10 The structure of the optical system 10 in this embodiment is the same as that in the first embodiment, and can be referred to accordingly.

[0092] Table 5a shows the characteristics of the optical system 10 in this embodiment. The meanings of each parameter are the same as those in the first embodiment, and will not be repeated here.

[0093] Table 5a

[0094]

[0095]

[0096] Table 5b shows the higher-order coefficients that can be used for each aspherical mirror in the fifth embodiment, wherein each aspherical surface shape can be defined by the formula given in the first embodiment.

[0097] Table 5b

[0098]

[0099] Figure 10The diagram shows the longitudinal spherical aberration, astigmatism, and distortion curves of the optical system according to the fifth embodiment. Figure 10 As can be seen from the aberration diagram, the longitudinal spherical aberration, field curvature, and distortion of the optical system are all well controlled, thus the optical system of this embodiment has good imaging quality.

[0100] Sixth Embodiment

[0101] Please refer to Figure 11 and Figure 12 The difference between the optical system 10 in this embodiment and the first embodiment is that the third lens L3 has positive refractive power. The other structures of the sixth embodiment are the same as those in the first embodiment, and can be referred to accordingly.

[0102] Table 6a shows the characteristics of the optical system 10 in this embodiment. The meanings of each parameter are the same as those in the first embodiment, and will not be repeated here.

[0103] Table 6a

[0104]

[0105] Table 6b shows the higher-order coefficients that can be used for each aspherical mirror in the sixth embodiment, wherein each aspherical surface shape can be defined by the formula given in the first embodiment.

[0106] Table 6b

[0107]

[0108]

[0109] Figure 12 The diagram shows the longitudinal spherical aberration, astigmatism, and distortion curves of the optical system according to the sixth embodiment. Figure 12 As can be seen from the aberration diagram, the longitudinal spherical aberration, field curvature, and distortion of the optical system are all well controlled, thus the optical system of this embodiment has good imaging quality.

[0110] Table 7 shows the values ​​of GL / Imgh, SD11 / SD52, D11 / RAD, ET5 / CT5, (|R31-R32|) / (|R31+R32|), ∑ET / ∑CT, (SD42+SD52) / Imgh, (ΣET*EPD) / f, f1 / R11, SAG51 / AT45, R41 / f, SD11 / SAG11, and FOV in the optical system 10 of the first to sixth embodiments.

[0111] Table 7

[0112]

[0113] The optical system 10 provided in the above embodiments can meet the characteristics of ultra-wide angle.

[0114] refer to Figure 13 This invention also provides a lens module 20, which includes the optical system 10 and a photosensitive chip 201 as described in any of the preceding embodiments. The photosensitive chip 201 is disposed on the image side of the optical system 10, and the two can be fixed by a bracket. The photosensitive chip 201 can be a CCD sensor (Charge Coupled Device) or a CMOS sensor (Complementary Metal Oxide Semiconductor). Generally, during assembly, the imaging surface (IMG) of the optical system 10 overlaps with the photosensitive surface of the photosensitive chip 201. By employing the above-described optical system 10, the lens module 20 can possess ultra-wide-angle characteristics.

[0115] refer to Figure 14 This invention also provides an electronic device 30. The electronic device 30 includes a housing 310 and a lens module 20 as described in the preceding embodiments. The lens module 20 is mounted on the housing 310, which can be a display screen, circuit board, mid-frame, back cover, or other components. The electronic device 30 can be, but is not limited to, VR (Virtual Reality) glasses, smartphones, smartwatches, e-book readers, tablets, biometric devices (such as fingerprint recognition devices or iris recognition devices), PDAs (Personal Digital Assistants), etc. Because the lens module 20 possesses ultra-wide-angle and high light-gathering characteristics, when the lens module 20 is used, the electronic device 30 can have an ultra-wide-angle feature, thereby achieving a larger shooting range and clearer image quality.

[0116] The above description discloses only some preferred embodiments of the present invention, and should not be construed as limiting the scope of the present invention. Those skilled in the art can understand that implementing all or part of the above embodiments and making equivalent changes in accordance with the claims of the present invention still fall within the scope of the present invention.

Claims

1. An optical system, characterized in that, The number of lenses with refractive power is five, which successively includes along the optical axis direction from the object side to the image side: A first lens with negative refractive power, the object side surface is concave near the optical axis, and the image side surface is concave near the optical axis; A second lens with positive refractive power, the object side surface is convex near the optical axis, and the image side surface is convex near the optical axis; A third lens with refractive power, the object side surface is convex near the optical axis, and the image side surface is concave near the optical axis; A fourth lens with positive refractive power; the object side surface is convex near the optical axis, and the image side surface is convex near the optical axis; A fifth lens with negative refractive power; the object side surface is convex near the optical axis, and the image side surface is concave near the optical axis; ​ ​ ​ 2. The optical system as claimed in claim 1, characterized in that, ​ ​ ​ 3. The optical system as described in claim 1, characterized in that, ​ ​ ​ 4. The optical system as claimed in claim 1, characterized in that, ​ ​ ​ 5. The optical system as claimed in claim 1, characterized in that, ​ ​ ​ 6. The optical system as claimed in claim 1, characterized in that, ​ ​ Where, ∑ET is the total edge thickness of all lenses in the optical system, EPD is the entrance pupil diameter of the optical system; f is the effective focal length of the optical system.

7. The optical system as claimed in claim 1, characterized in that, The optical system satisfies the relationship: 0.5 < f1 / R11 < 1, and / or 0.8 < R41 / f < 5; and / or 0 < (|R31 - R32|) / (|R31 + R32|) < 0.35; Where, f1 is the focal length of the first lens, R11 is the curvature radius of the object side of the first lens on the optical axis, R41 is the curvature radius of the object side of the fourth lens on the optical axis, f is the effective focal length of the optical system, R31 is the curvature radius of the object side of the third lens on the optical axis, and R32 is the curvature radius of the image side of the third lens on the optical axis.

8. A lens module, characterized in that, It includes the optical system and the photosensitive chip according to any one of claims 1 to 7, and the photosensitive chip is arranged on the image side of the optical system.

9. An electronic device, characterized in that, The electronic device includes a housing and the lens module according to claim 8, and the lens module is arranged in the housing.

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