Optical system, camera module and electronic equipment

Abstract

The invention provides an optical system, a camera module and electronic equipment. The optical system includes, in order from an object side to an image side, a first lens element with positive refractive power having a convex object-side surface and a concave image-side surface; a second lens element with positive refractive power having a convex object-side surface; the third lens element with negative refractive power has a concave image-side surface. A fourth lens element with negative refractive power having a concave object-side surface and a concave image-side surface; a fifth lens element with positive refractive power having a convex object-side surface and a convex image-side surface; a sixth lens element with positive refractive power having a convex object-side surface and a convex image-side surface; a seventh lens element with positive refractive power having a convex object-side surface; and the eighth lens has negative refractive power, the object side surface is a concave surface, the image side surface is a convex surface, and the optical system satisfies the following relational expressions: 25 < = FOV < = 30, and 1.5 < = FNO < = 1.75. The optical system provided by the invention has a long focal length and a large aperture, and can highlight a shooting main body while realizing long-distance clear imaging.

Description

Technical Field

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

[0002] As a key component for assisting intelligent driving systems in acquiring external information, automotive optical systems face increasing performance requirements as technology advances. Telephoto lenses are widely used due to their advantages, including clear imaging of distant objects, high magnification, and the ability to capture detailed features of distant objects. However, telephoto lenses often result in images of distant and nearby objects having similar clarity, making it difficult to highlight the subject. Therefore, achieving clear imaging at long distances while also highlighting the subject is a pressing issue in optical imaging technology. Summary of the Invention

[0003] The present application provides an optical system, a camera module and an electronic device. By making the optical system have the characteristics of long focal length and large aperture, the camera module equipped with the optical system can achieve clear imaging at a long distance while obtaining a shallow depth of field by blurring the background to highlight the shooting subject, ultimately achieving high-quality imaging pictures on the electronic device.

[0004] In a first aspect, an embodiment of the present application provides an optical system, which includes, in order from the object side to the image side along the optical axis: a first lens having positive refractive power, the object side surface of the first lens is convex at the near optical axis, and the image side surface of the first lens is concave at the near optical axis; a second lens having positive refractive power, the object side surface of the second lens is convex at the near optical axis; a third lens having negative refractive power, the image side surface of the third lens is concave at the near optical axis; a fourth lens having negative refractive power, the object side surface of the fourth lens is concave at the near optical axis, and the image side surface of the fourth lens is concave at the near optical axis; a fifth lens having positive refractive power, the object side surface of the fifth lens is convex at the near optical axis, and the image side surface of the fifth lens is concave at the near optical axis. The image side surface of the mirror is convex at the near optical axis; the sixth lens has positive refractive power, the object side surface of the sixth lens is convex at the near optical axis, and the image side surface of the sixth lens is convex at the near optical axis; the seventh lens has positive refractive power, and the object side surface of the seventh lens is convex at the near optical axis; the eighth lens has negative refractive power, the object side surface of the eighth lens is concave at the near optical axis, and the image side surface of the eighth lens is convex at the near optical axis; there are eight lenses with refractive power; the optical system satisfies the relationship: 25deg≤FOV≤30deg, 1.5≤FNO≤1.75, where FOV is the maximum field of view of the optical system, and FNO is the aperture number of the optical system.

[0005] The present invention provides a first lens element with positive refractive power, and the object side surface of the first lens element is convex at the near optical axis, and the image side surface of the first lens element is concave at the near optical axis, which is conducive to efficiently collecting light to increase the amount of light entering, and effectively reduces the field curvature and astigmatism of the optical system, thereby reducing the overall sensitivity of the optical system; and provides a second lens element with positive refractive power, and the object side surface of the second lens element is convex at the near optical axis, so that the second lens continues and enhances the light converging effect of the first lens, reasonably disperses the total positive optical power, and reduces the sensitivity of the optical system to the manufacturing tolerance of a single lens, and further Correction of spherical aberration; by making the third lens element have negative refractive power, and the image side surface of the third lens element is concave at the near optical axis, it is beneficial to avoid premature convergence of light, that is, forward focus shift, and fine adjustment of the deflection path of marginal light, and the high dispersion characteristic of the third lens element with negative refractive power can compensate for the dispersion produced by the front group positive lens, thereby significantly reducing the axial dispersion of the optical system; by making the fourth lens element have negative refractive power, and the object side surface of the fourth lens element is concave at the near optical axis, and the image side surface of the fourth lens element is concave at the near optical axis, it is beneficial to the entry and deflection of marginal light, which can reduce the rear lens The deflection angle borne by the mirror makes the deflection angle of light on each lens more uniform, effectively correcting the aberration of the peripheral field of view; by making the fifth lens have positive refractive power, and the object side surface of the fifth lens is convex at the near optical axis, and the image side surface of the fifth lens is convex at the near optical axis, it is beneficial to effectively collect and compress the incident light on the object side of the fifth lens, so that the light smoothly transitions to the other optical lenses on the image side of the fifth lens; by making the sixth lens have positive refractive power, and the object side surface of the sixth lens is convex at the near optical axis, and the image side surface of the sixth lens is convex at the near optical axis, it is beneficial to further reduce the aberration of the peripheral field of view. Low light height, and combined with the fifth lens element to form the rear achromatic unit of the optical system; by making the seventh lens element have positive refractive power and the object-side surface of the seventh lens element is convex at the near optical axis, it is beneficial for the seventh lens element to efficiently receive the light passing through the fifth lens element and the sixth lens element; by making the eighth lens element have negative refractive power and the object-side surface of the eighth lens element is concave at the near optical axis and the image-side surface of the eighth lens element is convex at the near optical axis, it is beneficial to achieve the final divergence of light with smaller aberrations, eliminate edge vignetting and color shift of light, and ultimately improve the consistency of resolution and contrast across the entire field of view of the optical system.

[0006] This application limits the maximum field of view of the optical system to this range by making the optical system satisfy the relationship: 25deg≤FOV≤30deg, which enables the optical system to avoid introducing excessive aberrations while achieving a longer focal length; by making the optical system satisfy the relationship: 1.5≤FNO≤1.75, which limits the aperture number of the optical system to this smaller range, the optical system can have a larger aperture, which is beneficial for the optical system to collect more light flux per unit time, obtain brighter and less noisy images under low light conditions, and enable the optical system to obtain a shallow depth of field by blurring the background to highlight the subject. The combination of the above-mentioned longer focal length and larger aperture enables the optical system to achieve clear imaging at a long distance while highlighting the subject.

[0007] In one possible embodiment, the optical system satisfies the relationship: 1.59 ≤ TTL / F ≤ 1.66, where TTL is the distance along the optical axis from the object-side surface of the first lens element to the imaging plane of the optical system, and F is the effective focal length of the optical system. Satisfying this relationship facilitates achieving the advantages of good aberrations, ease of manufacture, and miniaturization.

[0008] In one possible embodiment, the optical system satisfies the relationship: 6.2 ≤ TTL / IMGH ≤ 7.2, where TTL is the distance on the optical axis from the object-side surface of the first lens to the imaging plane of the optical system, and IMGH is half the image height corresponding to the maximum field of view of the optical system. By ensuring that the optical system satisfies this relationship, a reasonable ratio of the total length of the optical system to its image height is achieved. This, combined with the aforementioned maximum field of view range of the optical system, helps limit the total length of the optical system and achieves miniaturization of the optical system.

[0009] In one possible embodiment, the optical system satisfies the relationship: 16.5 degrees ≤ FOV / FNO ≤ 17.9 degrees, where FOV is the maximum field of view of the optical system, and FNO is the aperture number of the optical system. By ensuring that the optical system satisfies this relationship, the optical system has an appropriate field of view and aperture value, capable of collecting light within a medium angle range and achieving good imaging quality. If the value exceeds the upper limit of this relationship, excessive edge field distortion will result, causing distortion in the periphery of the image, which will in turn reduce the imaging performance of the optical system. If the value falls below the lower limit of this relationship, the aperture number of the optical system will be relatively large, resulting in insufficient light transmission through the optical system and reduced image clarity.

[0010] In one possible embodiment, the optical system satisfies the relationship: 0.9 ≤ F2 / F ≤ 1.3, where F is the effective focal length of the optical system and F2 is the effective focal length of the second lens element. Satisfying this relationship facilitates proper coordination of the refractive power of the second lens element within the optical system, simplifies and flexibly designs the surface profile of the second lens element, reduces aberrations, and effectively balances aberration correction and imaging quality for the overall optical system.

[0011] In one possible embodiment, the optical system satisfies the relationship: -3.5 ≤ F / F4 ≤ -2.4, where F is the effective focal length of the optical system and F4 is the effective focal length of the fourth lens element. By ensuring that the optical system satisfies this relationship, the fourth lens element is a negative lens with negative optical power. By controlling the negative optical power of the fourth lens element, the optical power of the entire optical system can be rationally distributed, facilitating correction of field curvature and chromatic aberration, and suppressing distortion, ultimately achieving high-quality imaging from the optical system.

[0012] In one possible embodiment, the optical system satisfies the relationship: 1.7 ≤ F / F5 ≤ 2.5, where F is the effective focal length of the optical system and F5 is the effective focal length of the fifth lens element. By ensuring that the optical system satisfies this relationship, the fifth lens element is a positive lens with positive refractive power. This allows the fifth lens element to efficiently converge light and reduce the sensitivity of the optical system by dispersing the positive refractive power.

[0013] In one possible embodiment, the optical system satisfies the relationship: -5 ≤ F45 / F ≤ -1, where F is the effective focal length of the optical system and F45 is the combined focal length of the fourth and fifth lenses. Satisfying this relationship allows the optical system to achieve excellent light divergence, lower manufacturing tolerances, and minimized aberrations and chromatic aberrations. If F45 / F < -5, overcorrection of field curvature, excessive distortion, and excessive back focus can result. If F45 / F > -1, significant chromatic aberration can occur.

[0014] In one possible embodiment, the optical system satisfies the relationship: 1.2 ≤ SD1 / IMGH ≤ 1.65, where SD1 is half the maximum effective aperture on the object side of the first lens element, and IMGH is half the image height corresponding to the maximum field of view of the optical system. By ensuring that the optical system satisfies this relationship, the entrance pupil of the optical system is larger, the amount of light entering the optical system per unit time is increased, the signal-to-noise ratio of the optical system under low light intensity is improved, and the advantages of miniaturization of the optical system are also taken into account.

[0015] In one possible embodiment, the optical system satisfies the relationship: 0.9 ≤ SD13 / SD12 ≤ 1.1, where SD12 is half the maximum effective aperture of the image-side surface of the sixth lens element, and SD13 is half the maximum effective aperture of the object-side surface of the seventh lens element. By ensuring that the optical system satisfies this relationship, the object-side surface aperture of the seventh lens element can fully cover the light emitted by the sixth lens element, thereby preventing the loss of light at the edge of the field of view. This also prevents an increase in the non-light-receiving area on the inner wall of the lens barrel of the seventh lens element due to an excessively large object-side surface aperture of the seventh lens element, thereby effectively suppressing the generation of reflected stray light in the optical system.

[0016] In one possible embodiment, the optical system satisfies the relationship: 1.3 ≤ SD1 / SD16 ≤ 1.7, where SD1 is half the maximum effective aperture of the object-side surface of the first lens element, and SD16 is half the maximum effective aperture of the image-side surface of the eighth lens element. By ensuring that the optical system satisfies this relationship, the image-side surface aperture of the eighth lens element is not too small, which helps reduce the angle of incidence of light on the imaging surface after passing through the eighth lens, thereby eliminating color shift and vignetting at the edges of the optical system's field of view. Furthermore, the image-side surface aperture of the eighth lens element is not too large, which helps control stray light from the eighth lens element, thereby preventing it from forming fog spots on the imaging surface, ultimately improving the imaging quality of the optical system.

[0017] In one possible embodiment, the optical system satisfies the relationship: 3.5 ≤ R2 / R1 ≤ 5.8, where R1 is the radius of curvature of the object-side surface of the first lens element at the optical axis, and R2 is the radius of curvature of the image-side surface of the first lens element at the optical axis. By ensuring that the optical system satisfies this relationship, incident light can be efficiently collected while effectively suppressing distortion. Furthermore, positive spherical aberration is generated on the object-side surface of the first lens element, while precise negative spherical aberration compensation is applied to marginal light on the image-side surface of the first lens element, maximizing spherical aberration correction efficiency.

[0018] In one possible embodiment, the optical system satisfies the relationship: -3 ≤ R7 / R8 ≤ -1.3, where R7 is the radius of curvature of the object-side surface of the fourth lens element at the optical axis, and R8 is the radius of curvature of the image-side surface of the fourth lens element at the optical axis. By ensuring that the optical system satisfies this relationship, the fourth lens element is a biconcave lens, which diffuses incoming light, effectively offsetting the strong converging force of the front positive lens group. This allows the light to spread more smoothly before reaching the image plane, facilitating the optical system's goal of achieving a long focal length.

[0019] In one possible embodiment, the optical system satisfies the relationship: 1.9 ≤ R16 / R15 ≤ 5.7, where R15 is the radius of curvature of the object-side surface of the eighth lens element at the optical axis, and R16 is the radius of curvature of the image-side surface of the eighth lens element at the optical axis. By ensuring that the optical system satisfies this relationship, the object-side surface of the eighth lens element is deeply concave to flatten the image field, while the image-side surface of the eighth lens element is gently convex to prevent image recurvature. This helps optimize the field curvature of the optical system and ultimately improves the imaging quality of the optical system.

[0020] In one possible embodiment, the optical system satisfies the relationship: 0.3 ≤ SAG8 / CT4 ≤ 2, where SAG8 is the sag of the image-side surface of the fourth lens element at maximum aperture, and CT4 is the thickness of the fourth lens element along the optical axis. Satisfying this relationship facilitates controlling the on-axis distance from the intersection of the image-side surface of the fourth lens element with the optical axis to the effective half-aperture vertex of the image-side surface of the second lens element, i.e., the back sag of the fourth lens element. This constrains the overall curvature of the fourth lens element and adjusts the light deflection angle, ensuring that light passing through the fourth lens element can enter the next lens group smoothly, achieving optimal imaging quality.

[0021] In one possible embodiment, the optical system satisfies the relationship: 2.1 ≤ CT2 / ET2 ≤ 3, where CT2 is the thickness of the second lens on the optical axis, and ET2 is the edge thickness of the second lens, i.e., the distance from the maximum effective aperture of the object-side surface of the second lens to the maximum effective aperture of the image-side surface of the second lens, parallel to the optical axis. By ensuring that the optical system satisfies this relationship, the ratio of the thickness of the second lens on the optical axis to its edge thickness is optimally configured, thereby simplifying the production and manufacturing of the second lens.

[0022] In one possible embodiment, the optical system satisfies the relationship: 3.1 ≤ CT2 / CT3 ≤ 3.95, where CT2 is the thickness of the second lens element along the optical axis, and CT3 is the thickness of the third lens element along the optical axis. By ensuring that the optical system satisfies this relationship, the second lens element is a thicker lens with positive optical power, which helps enhance light focusing capability; while the third lens element is a thinner lens with negative optical power, which helps improve dispersion control accuracy and reduce dispersion.

[0023] In one possible embodiment, the optical system satisfies the relationship: 2.4 ≤ CT34 / CT3 ≤ 4.7, where CT34 is the distance on the optical axis between the image-side surface of the third lens element and the object-side surface of the fourth lens element, and CT3 is the thickness of the third lens element on the optical axis. When the optical system satisfies this relationship, the air gap between the third and fourth lenses is relatively large, which helps disperse light and reduces spherical aberration and coma generated on the lens surfaces. This also prevents the gap between the third and fourth lenses from being too large, resulting in an excessively long optical system and the introduction of unnecessary stray light.

[0024] In one possible embodiment, the optical system satisfies the relationship: 0.8 ≤ CT78 / CT7 ≤ 3.5, where CT7 is the thickness of the seventh lens element on the optical axis, and CT78 is the distance on the optical axis between the image-side surface of the seventh lens element and the object-side surface of the eighth lens element. When the optical system satisfies this relationship, balancing the spacing between the seventh and eighth lenses results in smoother light in the final imaging stage, which helps improve the overall resolution and contrast of the optical system.

[0025] In one possible embodiment, the optical system satisfies the relationship: 0.28 ≤ CT67 / CT7 ≤ 1.3, where CT67 is the distance on the optical axis between the image-side surface of the sixth lens element and the object-side surface of the seventh lens element, and CT7 is the thickness of the seventh lens element on the optical axis. When the optical system satisfies this relationship, the air gap between the sixth and seventh lenses is limited to a small value. This facilitates close coupling of the sixth and seventh lenses, controls aberrations, and improves sharpness at the edges of the field of view. Furthermore, the gap between the sixth and seventh lenses is kept small to avoid light interference or diffraction issues.

[0026] In one possible embodiment, the optical system satisfies the relationship: 3.7 ≤ F / IMGH ≤ 4.5, where F is the effective focal length of the optical system and IMGH is half the image height corresponding to the optical system's maximum field of view. When the optical system satisfies this relationship, limiting the maximum field of view reduces edge aberrations, ensuring that the field of view is not too narrow to preserve a practical shooting range. This helps improve edge light resolution while maintaining a medium field of view and a long focal length.

[0027] In one possible embodiment, the optical system satisfies the relationship: 6.4 ≤ F / BFL ≤ 8.4, where F is the effective focal length of the optical system, and BFL is the distance along the optical axis from the image-side surface of the eighth lens element to the imaging plane of the optical system. When the optical system satisfies this relationship, it helps limit the back focal length, reducing the overall system length and achieving optical system miniaturization. It also ensures that the optical system has sufficient back focal space to accommodate other non-refractive lenses, such as infrared filters and protective glass.

[0028] In one possible embodiment, the optical system satisfies the relationship: 1.35 ≤ ΣCT / ΣAT ≤ 3, where ΣCT is the sum of the thicknesses of the first through eighth lenses on the optical axis, and ΣAT is the sum of the clearances between the first through eighth lenses on the optical axis. When the optical system satisfies this relationship, the proper configuration of the air gap effectively reduces the step difference between the lenses of the optical system, facilitates the support design of the lenses of the optical system, and improves the assembly yield of the optical system. If the relationship exceeds the upper limit, the lenses are too close together, easily causing collisions. If the relationship falls below the lower limit, the lenses are spaced too far apart, hindering assembly.

[0029] In a second aspect, the present application proposes a camera module comprising a lens barrel, an electronic photosensitive element, and the optical system of the first aspect, wherein the optical system is disposed within the lens barrel, and the electronic photosensitive element is disposed on the image side of the optical system. The electronic photosensitive element is used to convert light rays from an object that passes through the first lens to the eighth lens and is incident on the electronic photosensitive element into an electrical signal of an image. By installing the first lens to the eighth lens of the optical system within the camera module, rationally configuring the surface shape and refractive power of each lens of the first lens to the eighth lens, and rationally matching a larger focal length and aperture, the eight-lens optical system can simultaneously meet the requirements of clear imaging at a long distance and highlighting the subject of the photograph.

[0030] In a third aspect, the present application provides an electronic device comprising a main body and the camera module of the second aspect, wherein the camera module is disposed on the main body. By disposing the camera module in the electronic device, the present application enables the electronic device to simultaneously meet the requirements of long-distance clear imaging and highlighting the photographed subject. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0032] Figure 1 This is a schematic structural diagram of an electronic device provided by an embodiment of the present application;

[0033] Figure 2 is a structural diagram of the camera module in the first embodiment;

[0034] Figure 3 yes Figure 2 Schematic diagram of the optical system in FIG.

[0035] Figure 4 yes Figure 3The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system;

[0036] Figure 5 is a schematic structural diagram of the optical system of the second embodiment;

[0037] Figure 6 yes Figure 5 The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system;

[0038] Figure 7 is a schematic structural diagram of an optical system according to a third embodiment;

[0039] Figure 8 yes Figure 7 The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system;

[0040] Figure 9 is a schematic structural diagram of an optical system according to a fourth embodiment;

[0041] Figure 10 yes Figure 9 The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system;

[0042] Figure 11 is a schematic structural diagram of the optical system of the fifth embodiment;

[0043] Figure 12 yes Figure 11 The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system;

[0044] Figure 13 is a schematic structural diagram of the optical system of the sixth embodiment;

[0045] Figure 14 yes Figure 13 The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system;

[0046] Figure 15 is a schematic structural diagram of the optical system of the seventh embodiment;

[0047] Figure 16 yes Figure 15 The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system. DETAILED DESCRIPTION

[0048] Figure 1 This is a schematic diagram of the structure of an electronic device 30 provided in one embodiment of the present application. Figure 1 The embodiment of the present application provides an electronic device 30 , which may be a vehicle, for example. The electronic device 30 includes a main body 31 and a camera module 20 , wherein the camera module 20 is disposed on the main body 31 . Figure 1 The electronic device 30 in the embodiment is a vehicle, which is only an example and not a limitation of the embodiments of the present application. In fact, the electronic device 30 in the embodiments of the present application includes but is not limited to automobiles, monitoring equipment, mobile phones, computers, cameras, and wearable devices.

[0049] Figure 2 is a schematic structural diagram of the camera module 20 in the first embodiment, see Figure 2 The camera module 20 includes a photosensitive chip 201 and an optical system 10. The photosensitive chip 201 is disposed on the image side of the optical system 10. The photosensitive surface of the photosensitive chip 201 is located on the imaging surface of the optical system 10 and can convert light incident on the photosensitive surface from an object passing through the optical system 10 into an electrical signal. The photosensitive chip 201 can be a complementary metal oxide semiconductor (CMOS) or a charge-coupled device (CCD).

[0050] Figure 3 for Figure 2 Schematic diagram of the structure of the optical system 10. Figure 2 and Figure 3 As shown, the optical system 10 has a total of eight lenses with refractive power. Along the optical axis O, from the object side to the image side, they are the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the eighth lens L8. During imaging, light rays enter the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the eighth lens L8 in sequence from the object side of the first lens L1, and are ultimately imaged on the imaging surface IMG of the optical system 10. The imaging surface IMG can be located on the side of the photosensitive chip 201 in the camera module 20 that faces the eighth lens L8.

[0051] See Figure 3 The first lens L1 has positive refractive power, the object-side surface S1 of the first lens L1 is convex near the optical axis O, and the image-side surface S2 of the first lens L1 is concave near the optical axis O, which is conducive to efficiently collecting light to increase the amount of light entering, and effectively reduce the field curvature and astigmatism of the optical system, thereby reducing the overall sensitivity of the optical system.

[0052] See Figure 3The second lens element L2 has positive refractive power. In one possible embodiment, the object-side surface S3 of the second lens element L2 is convex at the near optical axis O, and the image-side surface S4 of the second lens element L2 may be convex at the near optical axis O. In another possible embodiment, the object-side surface S3 of the second lens element L2 is convex at the near optical axis O, and the image-side surface S4 of the second lens element L2 may be concave at the near optical axis O. The above configurations can enable the second lens element L2 to continue and enhance the light converging effect of the first lens element L1, reasonably disperse the total positive refractive power to reduce the optical system's sensitivity to manufacturing tolerances of individual lenses, and further correct spherical aberration.

[0053] See Figure 3 The third lens element L3 has negative refractive power. In one possible embodiment, the object-side surface S5 of the third lens element L3 may be convex at the near optical axis O, and the image-side surface S6 of the third lens element L3 may be concave at the near optical axis O. In another possible embodiment, the object-side surface S6 of the third lens element L3 may be concave at the near optical axis O, and the image-side surface S6 of the third lens element L3 may be concave at the near optical axis O. The above configurations are beneficial for preventing premature convergence of light, i.e., forward focus shift, and for finely adjusting the deflection path of marginal light. In addition, the high dispersion characteristics of the third lens element L3 with negative refractive power can compensate for the dispersion produced by the positive lens element in the front group, thereby significantly reducing the axial dispersion of the optical system.

[0054] See Figure 3 The fourth lens L4 has negative refractive power, the object-side surface S7 of the fourth lens L4 is concave at the near optical axis O, and the image-side surface S8 of the fourth lens L4 is concave at the near optical axis O, which is conducive to the entry and deflection of marginal light, and can reduce the deflection angle borne by the subsequent lens, so that the deflection angle of light on each lens is more uniform, effectively correcting the aberration of the marginal field of view.

[0055] See Figure 3 The fifth lens element L5 has positive refractive power. The object-side surface S9 of the fifth lens element L5 is convex at the near optical axis O, and the image-side surface S10 of the fifth lens element L5 is convex at the near optical axis O. This is conducive to effectively collecting and compressing the incident light from the object-side surface of the fifth lens element L5, so that the light smoothly transitions to the other optical lenses on the image-side surface of the fifth lens element L5.

[0056] See Figure 3 The sixth lens L6 has positive refractive power. The object-side surface S11 of the sixth lens L6 is convex near the optical axis O, and the image-side surface S12 of the sixth lens L6 is convex near the optical axis O, which is beneficial to further reduce the height of the light. It is combined with the fifth lens L5 to form the rear achromatic unit of the optical system.

[0057] See Figure 3The seventh lens element L7 has positive refractive power. In one possible embodiment, the object-side surface S13 of the seventh lens element L7 is convex at the near optical axis O, and the image-side surface S14 of the seventh lens element L7 may be convex at the near optical axis O. In another possible embodiment, the object-side surface S13 of the seventh lens element L7 is convex at the near optical axis O, and the image-side surface S14 of the seventh lens element L7 may be concave at the near optical axis O. In another possible embodiment, the object-side surface S13 of the seventh lens element L7 is convex at the near optical axis O, and the image-side surface S14 of the seventh lens element L7 may be flat at the near optical axis O. The above arrangements are conducive to the seventh lens element L7 efficiently receiving light rays passing through the fifth lens element L5 and the sixth lens element L6 and compressing the light rays, so that the light rays smoothly transition into the optical system on the image side of the seventh lens element L7.

[0058] See Figure 3 The eighth lens element L8 has negative refractive power, the object-side surface S15 of the eighth lens element L8 is concave near the optical axis O, and the image-side surface S16 of the eighth lens element L8 is convex near the optical axis O, which is conducive to achieving the final divergence of light with smaller aberrations, eliminating edge vignetting and color shift of light, and ultimately improving the consistency of resolution and contrast across the entire field of view of the optical system.

[0059] See Figure 3 In one possible embodiment, the optical system 10 may further include an aperture STO, which may be an aperture stop and / or a field stop. For example, the aperture STO may be an aperture stop, or the aperture STO may be a field stop, or the aperture STO may be an aperture stop and a field stop. The aperture STO may be used to adjust the amount of light entering the optical system 10. The position of the aperture STO may be determined according to product requirements, for example, it may be located between the third lens L3 and the fourth lens L4. In another embodiment, the aperture STO may be located between any two lenses, or located on the object side of the first lens L1, or located on the image side of the eighth lens L8, which is not limited in this embodiment.

[0060] See Figure 3In one possible embodiment, the optical system 10 further includes an IR filter. The IR filter may be an infrared cutoff filter IR, an infrared bandpass filter IR, or a double-pass filter IR. In the present application, the IR filter uses an infrared cutoff filter IR to filter out infrared light and only allow visible light to pass through, so that the imaging is more consistent with the visual experience of the human eye. Of course, the IR filter may also use an infrared bandpass filter IR, which is fixed relative to each lens in the optical system 10. The infrared bandpass filter IR is used to pass infrared light of the central wavelength and has the function of filtering out background stray light, and is used for infrared lenses. In addition, the IR filter may also use a double-pass filter IR, which can simultaneously transmit visible light with high transmittance and partially transmit infrared light, thereby achieving selection of different wavelength bands, and can realize both visible light imaging and infrared imaging, thereby achieving day and night versatility. The IR filter can be assembled with each lens as part of the optical system 10. In other embodiments, the IR filter can also be a separate component from the optical system 10, installed between the optical system 10 and the photosensitive chip during assembly. It is understood that the IR filter can be made of optical glass coating, tinted glass, or other materials, and the selection is based on practical needs and is not specifically limited in this embodiment. In other embodiments, a filter coating can be provided on at least one of the first through eighth lenses to achieve filtering.

[0061] See Figure 3 , at least one lens in the optical system 10 may have a spherical surface type. The spherical surface type design can reduce the difficulty of preparing the lens and reduce the preparation cost. In some embodiments, at least one lens of the optical system 10 may also have an aspherical surface type. When at least one side surface of the lens (object side or image side) is aspherical, the lens can be said to have an aspherical surface type. In some embodiments, the object side and image side of each lens can also be designed as aspherical surfaces. The aspherical design can help the optical system 10 to more effectively eliminate aberrations and improve imaging quality. In some embodiments, in order to take into account the preparation cost, preparation difficulty, imaging quality, assembly difficulty, etc., the design of each lens surface in the optical system 10 can be a combination of spherical and aspherical surface types. In this application, the sixth lens L6 has an aspherical surface type, and the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the seventh lens L7 and the eighth lens L8 have spherical surface types.

[0062] See Figure 3In the embodiment of the present application, the optical system 10 can satisfy the relationship: 25 degrees ≤ FOV ≤ 30 degrees, where FOV is the maximum field of view of the optical system 10. By ensuring that the optical system 10 satisfies the above relationship, the optical system 10 can achieve a longer focal length while avoiding the introduction of excessive aberrations, and is conducive to the optical system 10 obtaining a sufficient field of view.

[0063] See Figure 3 In the embodiment of the present application, the optical system 10 satisfies the relationship: 1.5≤FNO≤1.75, where FNO is the aperture number of the optical system. By ensuring that the optical system 10 satisfies the above relationship, a smaller aperture number can enable the optical system 10 to have a larger aperture, which helps the optical system 10 collect more light flux per unit time, obtain brighter images with less noise in low light conditions, and enable the optical system 10 to achieve a shallow depth of field by blurring the background to highlight the subject. The combination of the above medium field of view and the smaller aperture number enables the optical system 10 to achieve clear imaging at a long distance while highlighting the subject.

[0064] In summary, combined Figure 1 、 Figure 2 and Figure 3 As shown, the embodiment of the present application enables the optical system 10 to have the characteristics of long focal length and large aperture, so that clear imaging at a long distance can be achieved while obtaining a shallow depth of field by blurring the background to highlight the shooting subject and form a high-quality imaging picture.

[0065] The optical system 10 of the embodiment of the present application will be described in detail below with reference to specific parameters.

[0066] First embodiment,

[0067] Figure 3 yes Figure 2 A schematic structural diagram of the optical system 10; Figure 4 yes Figure 3 The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system 10 in FIG. Figure 3 and Figure 4As shown, the optical system 10 of this embodiment includes, in order from the object side to the image side along the optical axis O: a first lens L1 having positive refractive power, wherein the object-side surface S1 of the first lens L1 is convex at the near optical axis O, and the image-side surface S2 is concave at the near optical axis O. A second lens L2 having positive refractive power, wherein the object-side surface S3 of the second lens L2 is convex at the near optical axis O, and the image-side surface S4 of the second lens L2 is convex at the near optical axis O. A third lens L3 having negative refractive power, wherein the object-side surface S5 of the third lens L3 is concave at the near optical axis O, and the image-side surface S6 is concave at the near optical axis O. A fourth lens L4 having negative refractive power, wherein the object-side surface S7 of the fourth lens L3 is concave at the near optical axis O, and the image-side surface S8 of the fourth lens L4 is concave at the near optical axis O. The fifth lens element L5 has positive refractive power. The object-side surface S9 of the fifth lens element L5 is convex at the near optical axis O, and the image-side surface S10 is convex at the near optical axis O. The sixth lens element L6 has positive refractive power. The object-side surface S11 of the sixth lens element L6 is convex at the near optical axis O, and the image-side surface S12 is convex at the near optical axis O. The seventh lens element L7 has positive refractive power. The object-side surface S13 of the seventh lens element L7 is convex at the near optical axis O, and the image-side surface S14 is convex at the near optical axis O. The eighth lens element L8 has negative refractive power. The object-side surface S15 of the eighth lens element L8 is concave at the near optical axis O, and the image-side surface S16 is convex at the near optical axis O.

[0068] The materials of the first lens L1 to the eighth lens L8 are not limited, and they can all be made of glass, for example.

[0069] In addition, the optical system 10 also includes an aperture STO and a filter IR. The aperture STO is arranged on the side of the third lens L3 away from the second lens L2, and is used to control the amount of light entering. In other embodiments, the aperture STO can also be arranged between any two adjacent lenses; or, the aperture STO can also be arranged on the object side of the first lens L1; or, the aperture STO can also be arranged on the image side of the eighth lens L8. The filter IR is arranged on the image side of the eighth lens L8. The filter IR includes a surface S17 facing the surface of the eighth lens L8 and a surface S18 facing away from the surface S17. The filter IR can be used to filter out infrared light so that the light incident on the imaging surface IMG is visible light, and the wavelength of visible light is 380nm-780nm. The material of the filter IR is glass, and a film can be coated on the glass.

[0070] Table 1a shows the various parameters of the optical system 10 of this embodiment, wherein the Y radius is the radius of curvature of the object side or image side of the corresponding surface number at the optical axis O. Surface number S1 and surface number 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 a smaller surface number is the object side surface, and the surface with a 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, and the second value is the distance from the image side surface to the next surface of the lens in the image side direction on the optical axis. The focal length, material refractive index and Abbe number are all obtained using visible light with a reference wavelength of 558 nm. The units of the Y radius, thickness and effective focal length are all millimeters (mm);

[0071] Table 1a

[0072]

[0073]

[0074] Wherein, EFL is the effective focal length of the optical system 10, which is represented by F in the relationship equation of the optical system 10. FNO is the aperture number of the optical system 10, FOV is the field of view of the optical system 10, and IMGH is half of the image height corresponding to the maximum field of view of the optical system 10.

[0075] In this embodiment, both the object-side surface and the image-side surface of the sixth lens L6 are aspherical surfaces. The surface shape x of the aspherical lens can be defined by the following aspherical surface formula:

[0076]

[0077] Where x is the distance vector from the vertex of the aspheric surface at a height of h along the optical axis; c is the paraxial curvature of the aspheric surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the Y radius R in Table 1a above); k is the conic coefficient; Ai is the correction coefficient for the i-th order of the aspheric surface. Table 1b shows the conic coefficient k that can be used for the aspheric mirror surfaces S11-S12 in the first embodiment, as well as the higher-order coefficients A4, A6, A8, A10, A12, A14, and A16.

[0078] Table 1b

[0079]

[0080] Figure 4(a) shows the longitudinal spherical aberration curves of the optical system 10 of the first embodiment at wavelengths of 415.0000nm, 435.0000nm, 455.0000nm, 502.0000nm, 558.0000nm, 614.0000nm, and 661.0000nm, where the abscissa along the X-axis represents the focus offset, i.e., the distance from the imaging plane to the intersection of the light and the optical axis (in mm), and the ordinate along the Y-axis represents the normalized field of view. The longitudinal spherical aberration curves represent the deviation of the convergent focus of light of different wavelengths after passing through each lens of the optical system 10. Figure 4 As can be seen in (a), the degree of deviation of the convergent focus of light of different wavelengths in the first embodiment tends to be consistent, and the diffuse spots or color halo in the imaging image are effectively suppressed, indicating that the imaging quality of the optical system 10 in this embodiment is good.

[0081] Figure 4 (b) also shows the astigmatism curve of the optical system 10 of the first embodiment at a wavelength of 558.0000nm, where the horizontal axis along the X-axis represents the focus offset, and the vertical axis along the Y-axis represents the field angle, with the unit being degrees. The X curve in the astigmatism curve represents the sagittal field curvature at 558.0000nm, and the Y curve represents the meridional field curvature at 558.0000nm. Figure 4 As can be seen in (b), the field curvature of the optical system 10 is small, the field curvature and astigmatism of each field of view are well corrected, and clear images are obtained at the center and edge of the field of view.

[0082] Figure 4 (c) also shows the distortion curve of the optical system 10 of the first embodiment at a wavelength of 558.0000nm. The horizontal axis along the X-axis represents the distortion value in %, and the vertical axis along the Y-axis represents the field angle in degrees. The distortion curve represents the distortion value corresponding to different field angles. Figure 4 As can be seen in (c), at a wavelength of 558.0000 nm, the image deformation caused by the main beam is small, and the imaging quality of the system is excellent.

[0083] Depend on Figure 4 (a) Figure 4 (b) and Figure 4 As can be seen from (c), the optical system 10 of the first embodiment has small aberrations, good imaging quality, and excellent imaging quality.

[0084] Second embodiment,

[0085] Figure 5 is a schematic structural diagram of the optical system 10 according to the second embodiment, Figure 6 yes Figure 5The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system 10 in FIG. Figure 5 and Figure 6 The difference between the optical system 10 of the second embodiment and the optical system 10 of the first embodiment is that the image-side surface S14 of the seventh lens L7 of the optical system 10 of the second embodiment is a flat surface near the optical axis O.

[0086] The material of the first lens L1 to the eighth lens L8 is all glass.

[0087] In addition, the optical system 10 also includes an aperture STO, a filter IR and a protective glass CG. The aperture STO is arranged on the side of the third lens L3 away from the second lens L2, and is used to control the amount of light entering. In other embodiments, the aperture STO can also be arranged between two adjacent lenses, or on other lenses. The filter IR is arranged on the image side of the eighth lens L8, and includes a surface S17 facing the eighth lens L8 and a surface S18 facing away from the surface S17. The filter IR is used to filter out infrared light so that the light incident on the imaging surface IMG is visible light, and the wavelength of visible light is 380nm-780nm. The material of the filter IR is glass, and a film can be coated on the glass. The protective glass CG is arranged on the image side of the filter IR. The protective glass CG can be used to protect other lenses of the optical system 10 from damage from the external environment.

[0088] Table 2a shows the various parameters of the optical system 10 of this embodiment. The focal length, material refractive index, and Abbe number are all obtained using visible light with a reference wavelength of 558 nm. The units of the Y radius, thickness, and effective focal length are all millimeters (mm). The meanings of the other parameters are the same as those of the first embodiment.

[0089] Table 2a

[0090]

[0091] The meanings of the parameters in Table 2a are the same as those in the first embodiment.

[0092] Table 2b gives the high-order coefficients of each aspherical mirror surface that can be used in the second embodiment, wherein each aspherical surface shape can be defined by the formula given in the first embodiment.

[0093] Table 2b

[0094]

[0095] Figure 6 (a) Figure 6 (b) Figure 6(c) shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system 10 of the second embodiment. The longitudinal spherical aberration curve represents the deviation of the convergent focus of light of different wavelengths after passing through each lens of the optical system 10; the astigmatism curve represents the meridional image curvature and sagittal image curvature; and the distortion curve represents the distortion value corresponding to different field angles. Figure 6 It can be seen that the longitudinal spherical aberration, field curvature and distortion of the optical system 10 are all well controlled, so that the optical system 10 of the second embodiment has good imaging quality.

[0096] The third embodiment,

[0097] Figure 7 is a schematic structural diagram of the optical system 10 according to the third embodiment, Figure 8 yes Figure 7 The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system 10 in FIG. Figure 7 and Figure 8 The refractive power and surface shape design of each lens of the optical system 10 of the third embodiment are the same as those of the optical system 10 of the first embodiment.

[0098] Table 3a shows the various parameters of the optical system 10 of this embodiment. The focal length, material refractive index and Abbe number are all obtained using visible light with a reference wavelength of 558 nm. The units of the Y radius, thickness and effective focal length are all millimeters (mm). The meanings of the other parameters are the same as those of the first embodiment.

[0099] Table 3a

[0100]

[0101]

[0102] The meanings of the parameters in Table 3a are the same as those in the first embodiment.

[0103] Table 3b gives the high-order coefficients of each aspheric mirror surface that can be used in the third embodiment, wherein each aspheric surface shape can be defined by the formula given in the first embodiment.

[0104] Table 3b

[0105]

[0106] Figure 8 (a) Figure 8 (b) Figure 8(c) shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system 10 of the third embodiment. The longitudinal spherical aberration curve represents the deviation of the convergent focus of light of different wavelengths after passing through each lens of the optical system 10; the astigmatism curve represents the meridional image curvature and sagittal image curvature; and the distortion curve represents the distortion value corresponding to different field angles. Figure 8 It can be seen that the longitudinal spherical aberration, field curvature and distortion of the optical system 10 are all well controlled, and the optical system 10 of the third embodiment can achieve good imaging quality.

[0107] Fourth embodiment,

[0108] Figure 9 is a schematic structural diagram of the optical system 10 according to the fourth embodiment, Figure 10 yes Figure 9 The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system 10 in FIG. Figure 9 and Figure 10 The optical system 10 of the fourth embodiment differs from the optical system 10 of the first embodiment in that the image-side surface S4 of the second lens element L2 of the optical system 10 of the fourth embodiment is concave at the near optical axis O, the object-side surface S5 of the third lens element L3 is convex at the near optical axis O, and the image-side surface S14 of the seventh lens element L7 is concave at the near optical axis O.

[0109] Table 4a shows the various parameters of the optical system 10 of this embodiment. The focal length, material refractive index, and Abbe number are all obtained using visible light with a reference wavelength of 558 nm. The units of the Y radius, thickness, and effective focal length are all millimeters (mm). The meanings of the other parameters are the same as those of the first embodiment.

[0110] Table 4a

[0111]

[0112]

[0113] The meanings of the parameters in Table 4a are the same as those in the first embodiment.

[0114] Table 4b gives the high-order coefficients of the aspheric mirror surfaces that can be used in the fourth embodiment, wherein the aspheric surface shapes can be defined by the formula given in the first embodiment.

[0115] Table 4b

[0116]

[0117] Figure 10 (a) Figure 10 Middle (b), Figure 10(c) shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system 10 of the fourth embodiment. The longitudinal spherical aberration curve represents the deviation of the convergent focus of light of different wavelengths after passing through each lens of the optical system 10; the astigmatism curve represents the meridional image curvature and sagittal image curvature; and the distortion curve represents the distortion value corresponding to different field angles. Figure 10 It can be seen that the longitudinal spherical aberration, field curvature and distortion of the optical system 10 are all well controlled, and the optical system 10 of the fourth embodiment can achieve good imaging quality.

[0118] The fifth embodiment,

[0119] Figure 11 is a schematic structural diagram of the optical system 10 according to the fifth embodiment, Figure 12 yes Figure 11 The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system 10 in FIG. Figure 11 and Figure 12 The difference between the optical system 10 of the fifth embodiment and the optical system 10 of the first embodiment is that the image-side surface S14 of the seventh lens L7 of the optical system 10 of the fifth embodiment is concave near the optical axis O.

[0120] Table 5a shows the various parameters of the optical system 10 of this embodiment. The focal length, material refractive index and Abbe number are all obtained using visible light with a reference wavelength of 558 nm. The units of the Y radius, thickness and effective focal length are all millimeters (mm). The meanings of other parameters are the same as those of the first embodiment.

[0121] Table 5a

[0122]

[0123] The meanings of the parameters in Table 5a are the same as those in the first embodiment.

[0124] Table 5b gives the high-order coefficients of each aspherical mirror surface that can be used in the fifth embodiment, wherein each aspherical surface shape can be defined by the formula given in the first embodiment.

[0125] Table 5b

[0126]

[0127] Figure 12 (a) Figure 12 (b) Figure 12(c) shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system 10 of the fifth embodiment. The longitudinal spherical aberration curve represents the deviation of the convergent focus of light of different wavelengths after passing through each lens of the optical system 10; the astigmatism curve represents the meridional image curvature and sagittal image curvature; and the distortion curve represents the distortion value corresponding to different field angles. Figure 12 It can be seen that the longitudinal spherical aberration, field curvature and distortion of the optical system 10 are all well controlled, and the optical system 10 of the fifth embodiment can achieve good imaging quality.

[0128] Sixth embodiment,

[0129] Figure 13 is a schematic structural diagram of the optical system 10 according to the sixth embodiment, Figure 14 yes Figure 13 The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system 10 in FIG. Figure 13 and Figure 14 The optical system 10 of the sixth embodiment differs from the optical system 10 of the first embodiment in that the image-side surface S14 of the seventh lens L7 of the optical system 10 of the sixth embodiment is a flat surface near the optical axis O.

[0130] Table 6a shows the various parameters of the optical system 10 of this embodiment. The focal length, material refractive index and Abbe number are all obtained using visible light with a reference wavelength of 558 nm. The units of the Y radius, thickness and effective focal length are all millimeters (mm). The meanings of other parameters are the same as those of the first embodiment.

[0131] Table 6a

[0132]

[0133] The meanings of the parameters in Table 6a are the same as those in the first embodiment.

[0134] Table 6b gives the high-order coefficients of each aspheric mirror surface that can be used in the sixth embodiment, wherein each aspheric surface shape can be defined by the formula given in the first embodiment.

[0135] Table 6b

[0136]

[0137] Figure 14 (a) Figure 14 (b) Figure 14(c) shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system 10 of the sixth embodiment. The longitudinal spherical aberration curve represents the deviation of the convergent focus of light of different wavelengths after passing through each lens of the optical system 10; the astigmatism curve represents the meridional image curvature and sagittal image curvature; and the distortion curve represents the distortion value corresponding to different field angles. Figure 14 It can be seen that the longitudinal spherical aberration, field curvature and distortion of the optical system 10 are all well controlled, and the optical system 10 of the sixth embodiment can achieve good imaging quality.

[0138] Seventh embodiment,

[0139] Figure 15 is a schematic structural diagram of the optical system 10 according to the seventh embodiment, Figure 16 yes Figure 15 The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system 10 in FIG. Figure 15 and Figure 16 The difference between the optical system 10 of the seventh embodiment and the optical system 10 of the first embodiment is that the image-side surface S14 of the seventh lens L7 in the optical system 10 of the seventh embodiment is concave near the optical axis O.

[0140] Table 7a shows the various parameters of the optical system 10 of this embodiment. The focal length, material refractive index and Abbe number are all obtained using visible light with a reference wavelength of 558 nm. The units of the Y radius, thickness and effective focal length are all millimeters (mm). The meanings of other parameters are the same as those of the first embodiment.

[0141] Table 7a

[0142]

[0143] The meanings of the parameters in Table 7a are the same as those in the first embodiment.

[0144] Table 7b gives the high-order coefficients of each aspheric mirror surface that can be used in the seventh embodiment, wherein the surface shape of each aspheric surface can be defined by the formula given in the first embodiment.

[0145] Table 7b

[0146]

[0147] Figure 16 (a) Figure 16 (b) Figure 16(c) shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system 10 of the seventh embodiment. The longitudinal spherical aberration curve represents the deviation of the convergent focus of light of different wavelengths after passing through each lens of the optical system 10; the astigmatism curve represents the meridional image curvature and sagittal image curvature; and the distortion curve represents the distortion value corresponding to different field angles. Figure 16 It can be seen that the longitudinal spherical aberration, field curvature and distortion of the optical system 10 are all well controlled, and the optical system 10 of the seventh embodiment can achieve good imaging quality.

[0148] Table 8 shows the FOV, FNO, TTL / F, TTL / IMGH, FOV / FNO, F2 / F, F / F4, F / F5, F45 / F, SD1 / IMGH, SD13 / SD12, SD1 / SD16, R2 / R1, R7 / R8, R16 / R15, SAGS8 / CT4, CT2 / ET2, CT2 / CT3, CT34 / CT3, CT78 / CT7, CT67 / CT7, F / IMGH, F / BFL, ∑CT / ∑AT, F / F3, F6 / F, F7 / F, F8 / F, |R4 / R3|, |R5 / R6|, R10 / R9, R12 / R11, F2 / C The values ​​of T2, F3 / CT3, F4 / CT4, F5 / CT5, F6 / CT6, F7 / CT7, and F8 / CT8, where FOV is the maximum field of view of the optical system, FNO is the aperture number of the optical system, TTL is the distance from the object side of the first lens to the imaging plane of the optical system on the optical axis, IMGH is half of the image height corresponding to the maximum field of view of the optical system, F is the effective focal length of the optical system, F2 is the effective focal length of the second lens, F3 is the effective focal length of the third lens, F4 is the effective focal length of the fourth lens, F5 is the effective focal length of the fifth lens, F6 is the effective focal length of the sixth lens, F7 is the effective focal length of the seventh lens, F8 is the effective focal length of the eighth lens, and F45 is the combined focal length of the fourth and fifth lenses. , SD1 is half of the maximum effective aperture of the object side of the first lens, SD12 is half of the maximum effective aperture of the image side of the sixth lens, SD13 is half of the maximum effective aperture of the object side of the seventh lens, SD16 is half of the maximum effective aperture of the image side of the eighth lens, R1 is the radius of curvature of the object side of the first lens at the optical axis, R2 is the radius of curvature of the image side of the first lens at the optical axis, R3 is the radius of curvature of the object side of the second lens at the optical axis, R4 is the radius of curvature of the image side of the second lens at the optical axis, R5 is the radius of curvature of the object side of the third lens at the optical axis, R6 is the radius of curvature of the image side of the third lens at the optical axis, R7 is the radius of curvature of the object side of the fourth lens at the optical axis, and R8 is the radius of curvature of the image side of the fourth lens at the optical axis. The radius of curvature of the image side surface of the lens at the optical axis, R9 is the radius of curvature of the object side surface of the fifth lens at the optical axis, R10 is the radius of curvature of the image side surface of the fifth lens at the optical axis, R11 is the radius of curvature of the object side surface of the sixth lens at the optical axis, R12 is the radius of curvature of the image side surface of the sixth lens at the optical axis, R15 is the radius of curvature of the object side surface of the eighth lens at the optical axis, R16 is the radius of curvature of the image side surface of the eighth lens at the optical axis, SAG8 is the sag height of the image side surface of the fourth lens at the maximum aperture, CT2 is the thickness of the second lens on the optical axis, CT3 is the thickness of the third lens on the optical axis, CT4 is the thickness of the fourth lens on the optical axis, CT5 is the thickness of the fifth lens on the optical axis, and CT6 is the thickness of the sixth lens on the optical axis.CT7 is the thickness of the seventh lens on the optical axis, CT8 is the thickness of the eighth lens on the optical axis, CT34 is the distance on the optical axis between the image side surface of the third lens and the object side surface of the fourth lens, CT67 is the distance on the optical axis between the image side surface of the sixth lens and the object side surface of the seventh lens, CT78 is the distance on the optical axis between the image side surface of the seventh lens and the object side surface of the eighth lens, ET2 is the edge thickness of the second lens, BFL is the distance on the optical axis from the image side surface of the eighth lens to the imaging plane of the optical system, ΣCT is the sum of the thicknesses of the first to eighth lenses on the optical axis, and ΣAT is the sum of the gaps between the first to eighth lenses on the optical axis.

[0149] Table 8

[0150]

[0151]

[0152] As can be seen from Table 8, all embodiments satisfy the following relationships: 25≤FOV≤30, 1.5≤FNO≤1.75, 1.59≤TTL / F≤1.66, 6.2≤TTL / IMGH≤7.2, 16.5≤FOV / FNO≤17.9, 0.9≤F2 / F≤1.3, -3.5≤F / F4≤-2.4, 1.7≤F / F5≤2.5, -5≤F45 / F≤-1, 1.2≤ SD1 / IMGH≤1.65, 0.9≤SD13 / SD12≤1.1, 1.3≤SD1 / SD16≤1.7, 3.5≤R2 / R1≤5.8, -3≤R7 / R8≤-1. 3. 1.9≤R16 / R15≤5.7, 0.3≤SAGS8 / CT4≤2, 2.1≤CT2 / ET2≤3, 3.1≤CT2 / CT3≤3.95, 2.4≤CT34 / C T3≤4.7, 0.8≤CT78 / CT7≤3.5, 0.28≤CT67 / CT7≤1.3, 3.7≤F / IMGH≤4.5, 6.4≤F / BFL≤8.4, 1.35 ≤∑CT / ∑AT≤3, -2.8≤F / F3≤-2.1, 0.7≤F6 / F≤1.1, 0.8≤F7 / F≤1.3, -0.95≤F8 / F≤-0.65, 5≤|R4 / R3|≤65, 8≤|R5 / R6|≤85, -42≤R10 / R9≤-3, -8.1≤R12 / R11≤-2, 6≤F2 / CT2≤9.5, -13≤F3 / CT3≤- 8. -12≤F4 / CT4≤-1.5, 2.5≤F5 / CT5≤4.5, 3.2≤F6 / CT6≤6.8, 5≤F7 / CT7≤15, -19≤F8 / CT8≤-22.

[0153] The technical features of the above embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered to be within the scope of this specification.

[0154] The above embodiments merely illustrate several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art may make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. An optical system, characterized in that: There are eight lenses with refractive power, including the following from the object side to the image side along the optical axis: A first lens having positive refractive power, wherein the object-side surface of the first lens is convex at the near optical axis, and the image-side surface of the first lens is concave at the near optical axis; A second lens element having positive refractive power, wherein the object side surface of the second lens element is convex near the optical axis; A third lens element having negative refractive power, wherein the image side surface of the third lens element is concave near the optical axis; a fourth lens element having negative refractive power, wherein the object-side surface of the fourth lens element is concave near the optical axis, and the image-side surface of the fourth lens element is concave near the optical axis; a fifth lens element having positive refractive power, wherein the object-side surface of the fifth lens element is convex near the optical axis, and the image-side surface of the fifth lens element is convex near the optical axis; a sixth lens element having positive refractive power, wherein the object-side surface of the sixth lens element is convex near the optical axis, and the image-side surface of the sixth lens element is convex near the optical axis; a seventh lens element having positive refractive power, wherein the object-side surface of the seventh lens element is convex near the optical axis; an eighth lens element having negative refractive power, wherein the object-side surface of the eighth lens element is concave near the optical axis, and the image-side surface of the eighth lens element is convex near the optical axis; The optical system satisfies the relationship: 25deg≤FOV≤30deg, 1.5≤FNO≤1.75; Wherein, FOV is the maximum field of view of the optical system, and FNO is the aperture number of the optical system.

2. The optical system according to claim 1, wherein: The optical system satisfies the relationship: 1.59≤TTL / F≤1.66; and / or, 6.2 ≤ TTL / IMGH ≤ 7.2; and / or, 16.5deg≤FOV / FNO≤17.9deg; Wherein, TTL is the distance from the object side surface of the first lens to the imaging surface of the optical system on the optical axis, F is the effective focal length of the optical system, 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, wherein: The optical system satisfies the relationship: 0.9≤F2 / F≤1.3; and / or, -3.5≤F / F4≤-2.4; and / or, 1.7≤F / F5≤2.5; and / or, -5≤F45 / F≤-1; Among them, F2 is the effective focal length of the second lens, F4 is the effective focal length of the fourth lens, F5 is the effective focal length of the fifth lens, F45 is the combined focal length of the fourth lens and the fifth lens, and F is the effective focal length of the optical system.

4. The optical system according to claim 1, wherein The optical system satisfies the relationship: 1.2≤SD1 / IMGH≤1.65; and / or, 0.9≤SD13 / SD12≤1.1; and / or, 1.3≤SD1 / SD16≤1.7; Among them, SD1 is half of the maximum effective aperture of the object side surface of the first lens, SD12 is half of the maximum effective aperture of the image side surface of the sixth lens, SD13 is half of the maximum effective aperture of the object side surface of the seventh lens, SD16 is half of the maximum effective aperture of the image side surface of the eighth lens, and IMGH is half of the image height corresponding to the maximum field angle of the optical system.

5. The optical system according to claim 1, wherein: The optical system satisfies the relationship: 3.5≤R2 / R1≤5.8; and / or, -3≤R7 / R8≤-1.3; and / or, 1.9≤R16 / R15≤5.7; Wherein, R1 is the radius of curvature of the object side surface of the first lens at the optical axis, R2 is the radius of curvature of the image side surface of the first lens at the optical axis, R7 is the radius of curvature of the object side surface of the fourth lens at the optical axis, R8 is the radius of curvature of the image side surface of the fourth lens at the optical axis, R15 is the radius of curvature of the object side surface of the eighth lens at the optical axis, and R16 is the radius of curvature of the image side surface of the eighth lens at the optical axis.

6. The optical system according to claim 1, wherein: The optical system satisfies the relationship: 0.3≤SAG8 / CT4≤2; and / or, 2.1≤CT2 / ET2≤3; and / or, 3.1≤CT2 / CT3≤3.95; Among them, SAG8 is the sag height of the image side surface of the fourth lens at the maximum aperture, ET2 is the edge thickness of the second lens, 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.

7. The optical system according to claim 1, wherein: The optical system satisfies the relationship: 2.4≤CT34 / CT3≤4.7; and / or, 0.8≤CT78 / CT7≤3.5; and / or, 0.28≤CT67 / CT7≤1.3; Among them, CT3 is the thickness of the third lens on the optical axis, CT7 is the thickness of the seventh lens on the optical axis, CT34 is the distance between the image side surface of the third lens and the object side surface of the fourth lens on the optical axis, CT67 is the distance between the image side surface of the sixth lens and the object side surface of the seventh lens on the optical axis, and CT78 is the distance between the image side surface of the seventh lens and the object side surface of the eighth lens on the optical axis.

8. The optical system according to claim 1, wherein: The optical system satisfies the relationship: 3.7≤F / IMGH≤4.5; and / or, 6.4≤F / BFL≤8.4; and / or, 1.35≤ΣCT / ΣAT≤3; and / or; Wherein, F is the effective focal length of the optical system, IMGH is half the image height corresponding to the maximum field of view of the optical system, BFL is the distance from the image-side surface of the eighth lens to the imaging plane of the optical system on the optical axis, ΣCT is the sum of the thicknesses of the first lens to the eighth lens on the optical axis, and ΣAT is the sum of the gaps between the first lens and the eighth lens on the optical axis.

9. A camera module, characterized in that: The optical system comprises a lens barrel, an electronic photosensitive element, and the optical system according to any one of claims 1 to 8, wherein the optical system is arranged in the lens barrel, and the electronic photosensitive element is arranged on the image side of the optical system.

10. An electronic device, characterized in that: It comprises a main body and the camera module according to claim 9, wherein the camera module is arranged on the main body.

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