Optical system, camera module and electronic device

Abstract

This application provides an optical system, a camera module, and an electronic device. The optical system, from the object side to the image side, sequentially includes: a first lens with positive refractive power, a convex object side surface, and a concave image side surface; a second lens with positive refractive power, a convex object side surface; a third lens with negative refractive power, a concave image side surface; a fourth lens with negative refractive power, a concave object side surface, and a concave image side surface; a fifth lens with positive refractive power, a convex object side surface, and a convex image side surface; a sixth lens with positive refractive power, a convex object side surface, and a convex image side surface; a seventh lens with positive refractive power, a convex object side surface; and an eighth lens with negative refractive power, a concave object side surface, and a convex image side surface. The optical system satisfies the following relationships: 25 ≤ FOV ≤ 30, 1.5 ≤ FNO ≤ 1.75. The optical system provided by this application combines a long focal length and a large aperture, enabling clear imaging at long distances while highlighting the subject being photographed.

Description

Technical Field

[0001] This 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 Technology

[0002] As a key component in assisting intelligent driving systems to acquire external information, the performance requirements of automotive optical systems are continuously upgrading with technological advancements. Among these, telephoto lenses are widely used due to their advantages such as clear imaging of distant objects, high magnification, and the ability to reveal 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, how to achieve clear imaging at long distances while simultaneously highlighting the subject is a pressing problem in the field of optical imaging technology. Summary of the Invention

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

[0004] In a first aspect, embodiments of this application provide an optical system comprising, sequentially from the object side to the image side along the optical axis: a first lens having positive refractive power, wherein the object side of the first lens is convex near the optical axis, and the image side of the first lens is concave near the optical axis; a second lens having positive refractive power, wherein the object side of the second lens is convex near the optical axis; a third lens having negative refractive power, wherein the image side of the third lens is concave near the optical axis; a fourth lens having negative refractive power, wherein the object side of the fourth lens is concave near the optical axis, and the image side of the fourth lens is concave near the optical axis; a fifth lens having positive refractive power, wherein the object side of the fifth lens is convex near the optical axis, and the image side of the fifth lens is convex near the optical axis; and a sixth lens having positive refractive power. The object-side surface of the first lens is convex near the optical axis, and the image-side surface of the sixth lens is convex near the optical axis. The seventh lens has positive refractive power, and its object-side surface is convex near the optical axis. The eighth lens has negative refractive power, and its object-side surface is concave near the optical axis, while its image-side surface is convex near the optical axis. There are eight lenses with refractive power. The optical system satisfies the following relationships: 25deg≤FOV≤30deg, 1.5≤FNO≤1.75, 1.59≤TTL / F≤1.66, 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 on the optical axis from the object-side surface of the first lens to the imaging plane of the optical system, and F is the effective focal length of the optical system.

[0005] This application, by giving the first lens positive refractive power and making its object-side surface convex near the optical axis and its image-side surface concave near the optical axis, facilitates efficient light collection to increase the amount of light received, effectively reduces field curvature and astigmatism in the optical system, and lowers the overall sensitivity of the optical system. By giving the second lens positive refractive power and making its object-side surface convex near the optical axis, the second lens continues and enhances the light-convexity effect of the first lens, rationally dispersing the total positive optical power to reduce the sensitivity of the optical system to the manufacturing tolerances of individual lenses, and further… Correcting spherical aberration; by making the third lens have negative refractive power and its image-side surface concave near the optical axis, it helps to avoid premature convergence of light rays, i.e., focal forward shift, and allows for fine adjustment of the deflection path of edge rays. Furthermore, the high dispersion characteristics of the third lens with negative refractive power can compensate for the dispersion generated by the preceding positive lenses, thus significantly reducing the axial dispersion of the optical system. By making the fourth lens have negative refractive power and its object-side surface concave near the optical axis, and its image-side surface concave near the optical axis, it facilitates the entry and deflection of edge rays, reducing the backscattering. The deflection angle borne by the lens ensures a more uniform deflection angle of light across all lenses, effectively correcting aberrations at the edges of the field of view. By giving the fifth lens positive refractive power, and ensuring that both its object-side and image-side surfaces are convex near the optical axis, it effectively collects and compresses incident light rays from the object side of the fifth lens, allowing for a smooth transition of light to the other optical lenses on the image side. Furthermore, by giving the sixth lens positive refractive power, and ensuring that both its object-side and image-side surfaces are convex near the optical axis, it further reduces... The low light height, combined with the fifth lens, forms the rear achromatic unit of the optical system; by giving the seventh lens positive refractive power and making its object-side surface convex near the optical axis, the seventh lens can efficiently receive light transmitted through the fifth and sixth lenses; by giving the eighth lens negative refractive power and making its object-side surface concave near the optical axis and its image-side surface convex near the optical axis, the final divergence of light is achieved with smaller aberrations, eliminating vignetting and color shift at the edges of the light, and ultimately improving the consistency of the optical system's full field-of-view resolution and contrast.

[0006] This application limits the maximum field of view of the optical system to within the range of 25deg≤FOV≤30deg, enabling the optical system to achieve a longer focal length while avoiding excessive aberrations. By satisfying the relationship 1.5≤FNO≤1.75, the aperture number of the optical system is limited to a smaller range, allowing for a larger aperture. This facilitates the collection of more light flux per unit time, resulting in brighter, less noisy images in low-light conditions, and enabling the optical system to achieve a shallow depth of field by blurring the background to highlight the subject. Furthermore, by satisfying the relationship 1.59≤TTL / F≤1.66, the advantages of good aberrations, ease of manufacturing, and miniaturization are balanced. The combination of a longer focal length and a larger aperture allows the optical system to achieve clear imaging at long distances while simultaneously highlighting the subject.

[0007] In one possible implementation, the optical system satisfies the relationship: 6.2 ≤ TTL / IMGH ≤ 7.2, where TTL is the distance along the optical axis from the object-side surface of the first lens to the imaging surface 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 the above relationship, the ratio of the total length of the optical system to the image height can be reasonably configured. Combined with the range of the maximum field of view of the optical system, this helps to limit the total length of the optical system and achieve miniaturization.

[0008] In one possible implementation, the optical system satisfies the relationship: 16.5deg ≤ FOV / FNO ≤ 17.9deg, 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 the above relationship, it is limited to have a suitable field of view and aperture value, enabling it to collect light within a moderate angular range and obtain good image quality. If the value exceeds the upper limit of the above relationship, it will lead to excessive edge field of view distortion, resulting in image distortion at the periphery and thus a decrease in the imaging performance of the optical system; if the value is below the lower limit of the above relationship, the aperture number of the optical system is relatively large, resulting in insufficient light transmission and a decrease in the sharpness of the captured image.

[0009] In one possible implementation, 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. By ensuring that the optical system satisfies the above relationship, the refractive power of the second lens in the optical system is properly matched, the surface design of the second lens is simpler and more flexible, aberrations are reduced, and the overall aberration correction and imaging quality of the optical system are effectively balanced.

[0010] In one possible implementation, 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. By ensuring the optical system satisfies this relationship, the fourth lens becomes a negative lens with negative optical power. By controlling the negative optical power of the fourth lens, the optical power of the entire optical system can be rationally allocated, which is beneficial for correcting field curvature and chromatic aberration, as well as suppressing distortion, ultimately achieving high-quality imaging of the optical system.

[0011] In one possible implementation, 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. By making the optical system satisfy the above relationship, the fifth lens is a positive lens with positive optical power, which enables the fifth lens to efficiently converge light and reduce the sensitivity of the optical system by dispersing the positive optical power.

[0012] In one possible implementation, 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. By satisfying this relationship, the optical system can achieve a balance of good light divergence, lower manufacturing tolerances, and smaller aberrations and chromatic aberrations. If F45 / F < -5, it will lead to overcorrection of field curvature, excessive distortion, and an excessively long back focal length; if F45 / F > -1, it will result in significant chromatic aberration.

[0013] In one possible implementation, the optical system satisfies the relationship: 1.2 ≤ SD1 / IMGH ≤ 1.65, where SD1 is half the maximum effective aperture of the object-side surface of the first lens, and IMGH is half the image height corresponding to the maximum field of view of the optical system. By making the optical system satisfy the above relationship, the entrance pupil of the optical system is larger, the amount of light entering the optical system per unit time is larger, 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.

[0014] In one possible implementation, 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, and SD13 is half the maximum effective aperture of the object-side surface of the seventh lens. By ensuring the optical system satisfies this relationship, the object-side aperture of the seventh lens can completely cover the emitted light from the sixth lens, thus avoiding the loss of edge field-of-view rays. Furthermore, it avoids an excessively large object-side aperture of the seventh lens, which would increase the non-light-receiving area on the inner wall of the seventh lens barrel, thus helping to suppress the generation of reflected stray light from the optical system.

[0015] In one possible implementation, 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, and SD16 is half the maximum effective aperture of the image-side surface of the eighth lens. By ensuring the optical system satisfies this relationship, the image-side aperture of the eighth lens is not too small, which helps to reduce the angle of incidence formed on the imaging surface after light passes through the eighth lens, thereby eliminating color shift and vignetting at the edge of the optical system's field of view. Furthermore, the image-side aperture of the eighth lens is not too large, which helps to control stray light from the eighth lens, thus preventing stray light from forming haze on the imaging surface, ultimately ensuring the imaging quality of the optical system.

[0016] In one possible implementation, 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 at the optical axis, and R2 is the radius of curvature of the image-side surface of the first lens at the optical axis. By ensuring the optical system satisfies this relationship, distortion can be effectively suppressed while efficiently collecting incident light. Furthermore, the object-side surface of the first lens generates positive spherical aberration, and the image-side surface of the first lens applies precise negative spherical aberration compensation to edge rays, which helps to maximize spherical aberration correction efficiency.

[0017] In one possible implementation, 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 at the optical axis, and R8 is the radius of curvature of the image-side surface of the fourth lens at the optical axis. By making the optical system satisfy the above relationship, the fourth lens is a double-concave lens, which can diffuse the passing light, effectively counteracting the strong converging force of the front positive lens group, allowing the light to spread more smoothly before reaching the imaging plane, which is beneficial for achieving the long focal length target of the optical system.

[0018] In one possible implementation, 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 at the optical axis, and R16 is the radius of curvature of the image-side surface of the eighth lens at the optical axis. By making the optical system satisfy the above relationship, the object-side surface of the eighth lens is deeply concave to flatten the image field, and the image-side surface of the eighth lens is gently convex to avoid image plane inversion. This helps to optimize the field curvature of the optical system and ultimately improves the imaging quality of the optical system.

[0019] In one possible implementation, 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 at its maximum aperture, and CT4 is the thickness of the fourth lens along the optical axis. By ensuring the optical system satisfies this relationship, it is beneficial to control the axial distance from the intersection of the image-side surface of the fourth lens and the optical axis to the effective half-aperture vertex of the image-side surface of the second lens, i.e., the back sag of the fourth lens. This constrains the curvature of the overall shape of the fourth lens, adjusts the light deflection angle, and allows light rays to enter the next lens group effectively after passing through the fourth lens, thus achieving optimal image quality.

[0020] In one possible implementation, the optical system satisfies the relationship: 2.1 ≤ CT2 / ET2 ≤ 3, where CT2 is the thickness of the second lens along the optical axis, and ET2 is the edge thickness of the second lens, which is the distance from the maximum effective aperture on the object side to the maximum effective aperture on the image side of the second lens in the direction parallel to the optical axis. By ensuring that the optical system satisfies the above relationship, the ratio of the thickness of the second lens along the optical axis to the edge thickness of the second lens can be rationally configured, which helps to simplify the production and manufacturing of the second lens.

[0021] In one possible implementation, the optical system satisfies the relationship: 3.1 ≤ CT2 / CT3 ≤ 3.95, where CT2 is the thickness of the second lens along the optical axis, and CT3 is the thickness of the third lens along the optical axis. By making the optical system satisfy the above relationship, the second lens is a thicker lens with positive optical power, which is beneficial for enhancing light-gathering ability; and the third lens is a thinner lens with negative optical power, which is beneficial for improving dispersion control accuracy and reducing dispersion.

[0022] In one possible implementation, 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 and the object-side surface of the fourth lens, and CT3 is the thickness of the third lens on the optical axis. When the optical system satisfies the above relationship, the air gap between the third and fourth lenses is relatively large, which helps to disperse light and reduce spherical aberration and coma generated on the lens surfaces. It also prevents the optical system from becoming too long due to excessive spacing between the third and fourth lenses, and avoids the introduction of unwanted stray light.

[0023] In one possible implementation, the optical system satisfies the relationship: 0.8 ≤ CT78 / CT7 ≤ 3.5, where CT7 is the thickness of the seventh lens on the optical axis, and 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. When the optical system satisfies the above relationship, by balancing the interval between the seventh and eighth lenses, the light in the final imaging stage is smoother, which is beneficial to improving the overall resolution and contrast of the optical system.

[0024] In one possible implementation, 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 and the object-side surface of the seventh lens, and CT7 is the thickness of the seventh lens on the optical axis. When the optical system satisfies the above relationship, the air gap between the sixth and seventh lenses is kept small, which helps to tightly couple the sixth and seventh lenses, control aberrations, and improve the sharpness of the edge field of view. At the same time, it ensures that the gap between the sixth and seventh lenses is not too small, avoiding light interference or diffraction problems.

[0025] In one possible implementation, 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 maximum field of view of the optical system. When the optical system satisfies the above relationship, limiting the maximum field of view reduces edge aberrations and ensures that the field of view is not too small to retain a practical shooting range. This is beneficial for improving edge light resolution while maintaining a medium field of view and a long focal length.

[0026] In one possible implementation, 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 to the imaging plane of the optical system. When the optical system satisfies this relationship, it helps to limit the back focal length, reduce the overall system length, and achieve miniaturization of the optical system. Furthermore, it ensures that the optical system has sufficient back focal space to accommodate other non-refractive lenses, such as infrared filters and protective glass.

[0027] In one possible implementation, the optical system satisfies the relationship: 1.35 ≤ ΣCT / ΣAT ≤ 3, where ΣCT is the sum of the thicknesses of the first to eighth lenses along the optical axis, and ΣAT is the sum of the gaps between the first to eighth lenses along the optical axis. When the optical system satisfies the above relationship, the step difference between the lenses in the optical system can be effectively shortened by reasonably configuring the air gaps, which is beneficial to the bearing design of the lenses in the optical system and improves the assembly yield of the optical system. If the upper limit of the relationship is exceeded, the lenses are too close together, which can easily lead to collisions between the lenses; if the lower limit of the relationship is below the lower limit, the gaps between the lenses are too large, which is not conducive to the assembly of the lenses.

[0028] Secondly, this application proposes a camera module including a lens barrel, an electronic photosensitive element, and an optical system as described in the first aspect. 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 passing through the first to eighth lenses and incident on the electronic photosensitive element into electrical signals for an image. By installing the first to eighth lenses of this optical system within the camera module, and by rationally configuring the surface shape and refractive power of each lens, and by appropriately matching a large focal length and aperture, this application enables the eight-element optical system to simultaneously meet the requirements of clear imaging at long distances and highlighting the subject being photographed.

[0029] Thirdly, this application proposes an electronic device, including a main body and a camera module as described in the second aspect, wherein the camera module is disposed in the main body. By incorporating the aforementioned camera module into the electronic device, this application enables the electronic device to simultaneously meet the requirements of clear imaging at long distances and highlighting the subject being photographed. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of this application 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 this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 This is a schematic diagram of the structure of an electronic device provided in one embodiment of this application; Figure 2 This is a schematic diagram of the camera module in the first embodiment; Figure 3 yes Figure 2 A schematic diagram of the optical system in the diagram; Figure 4 yes Figure 3 The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system in the image; Figure 5 This is a schematic diagram of the optical system of the second embodiment; Figure 6 yes Figure 5 The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system in the image; Figure 7 This is a schematic diagram of the optical system of the third embodiment; Figure 8 yes Figure 7 The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system in the image; Figure 9 This is a schematic diagram of the optical system in the fourth embodiment; Figure 10 yes Figure 9 The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system in the image; Figure 11 This is a schematic diagram of the optical system of the fifth embodiment; Figure 12 yes Figure 11 The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system in the image; Figure 13 This is a schematic diagram of the optical system in the sixth embodiment; Figure 14 yes Figure 13 The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system in the image; Figure 15 This is a schematic diagram of the optical system of the seventh embodiment; Figure 16 yes Figure 15 The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system in the image. Detailed Implementation

[0032] Figure 1 This is a schematic diagram of the structure of an electronic device 30 provided in one embodiment of this application. (See attached diagram.) Figure 1 This application provides an electronic device 30, which may be, for example, a vehicle. 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 this example is a vehicle; this is merely an example and not a limitation on the embodiments of this application. In fact, the electronic device 30 in the embodiments of this application includes, but is not limited to, automobiles, monitoring equipment, mobile phones, computers, cameras, and wearable devices.

[0033] Figure 2 This is a schematic diagram of the camera module 20 in the first embodiment, see reference. 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 it can convert light from an object incident on the photosensitive surface 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).

[0034] Figure 3 for Figure 2 A schematic diagram of the optical system 10 in the diagram. (Combined with...) Figure 2 and Figure 3 As shown, the optical system 10 has eight lenses with refractive power, arranged sequentially from the object side to the image side along the optical axis O: first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, seventh lens L7, and eighth lens L8. During imaging, light rays enter the first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, seventh lens L7, and eighth lens L8 sequentially from the object side of the first lens L1, and are finally imaged onto 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 facing the eighth lens L8.

[0035] See Figure 3 The first lens L1 has positive refractive power. The object side S1 of the first lens L1 is convex near the optical axis O, and the image side S2 of the first lens L1 is concave near the optical axis O. This is beneficial for efficiently collecting light to increase the amount of light entering the system, and effectively reducing the field curvature and astigmatism of the optical system, thereby reducing the overall sensitivity of the optical system.

[0036] See Figure 3 The second lens L2 has positive refractive power. In one possible implementation, the object-side surface S3 of the second lens L2 is convex near the optical axis O, and the image-side surface S4 of the second lens L2 can also be convex near the optical axis O. In another possible implementation, the object-side surface S3 of the second lens L2 is convex near the optical axis O, and the image-side surface S4 of the second lens L2 can be concave near the optical axis O. Both of these configurations allow the second lens L2 to continue and enhance the light-converging effect of the first lens L1, reasonably dispersing the total positive optical power to reduce the sensitivity of the optical system to the manufacturing tolerances of a single lens, and further correcting spherical aberration.

[0037] See Figure 3 The third lens L3 has negative refractive power. In one possible implementation, the object-side surface S5 of the third lens L3 can be convex near the optical axis O, and the image-side surface S6 of the third lens L3 can be concave near the optical axis O. In another possible implementation, the object-side surface S6 of the third lens L3 can be concave near the optical axis O, and the image-side surface S6 of the third lens L3 can be concave near the optical axis O. Both of these configurations help to avoid premature convergence of light, i.e., focal forward shift, and to finely adjust the deflection path of peripheral light rays. Furthermore, the high dispersion characteristics of the third lens L3 with negative refractive power can compensate for the dispersion generated by the front positive lens group, thereby significantly reducing the axial dispersion of the optical system.

[0038] See Figure 3The fourth lens L4 has negative refractive power. The object side S7 of the fourth lens L4 is concave near the optical axis O, and the image side S8 of the fourth lens L4 is also concave near the optical axis O. This facilitates the entry and deflection of edge light rays, reduces the deflection angle borne by the subsequent lenses, and makes the deflection angle of light rays on each lens more uniform, effectively correcting aberrations in the edge field of view.

[0039] See Figure 3 The fifth lens L5 has positive refractive power. The object-side surface S9 of the fifth lens L5 is convex near the optical axis O, and the image-side surface S10 of the fifth lens L5 is convex near the optical axis O. This is beneficial for effectively collecting and compressing the incident light rays from the object-side surface of the fifth lens L5, so that the light rays can smoothly transition to other optical lenses on the image-side surface of the fifth lens L5.

[0040] See Figure 3 The sixth lens L6 has positive refractive power. The object side S11 of the sixth lens L6 is convex near the optical axis O, and the image side S12 of the sixth lens L6 is convex near the optical axis O. This is beneficial to further reduce the height of the light rays and, together with the fifth lens L5, forms the rear achromatic unit of the optical system.

[0041] See Figure 3 The seventh lens L7 has positive refractive power. In one possible implementation, the object-side surface S13 of the seventh lens L7 is convex near the optical axis O, and the image-side surface S14 of the seventh lens L7 can also be convex near the optical axis O. In another possible implementation, the object-side surface S13 of the seventh lens L7 is convex near the optical axis O, and the image-side surface S14 of the seventh lens L7 can be concave near the optical axis O. In yet another possible implementation, the object-side surface S13 of the seventh lens L7 is convex near the optical axis O, and the image-side surface S14 of the seventh lens L7 can be flat near the optical axis O. All of these configurations facilitate the efficient reception and compression of light transmitted through the fifth lens L5 and the sixth lens L6 by the seventh lens L7, allowing the light to smoothly transition to the image side of the seventh lens L7 in the optical system.

[0042] See Figure 3 The eighth lens L8 has negative refractive power. The object side S15 of the eighth lens L8 is concave near the optical axis O, and the image side S16 of the eighth lens L8 is convex near the optical axis O. This is beneficial to achieve the final divergence of light with smaller aberrations, eliminate the edge vignetting and color shift of light, and ultimately improve the consistency of the full field of view resolution and contrast of the optical system.

[0043] See Figure 3In one possible implementation, the optical system 10 may further include an aperture stop STO, which may be an aperture stop and / or a field stop. For example, the aperture stop STO may be an aperture stop, or a field stop, or both an aperture stop and a field stop. The aperture stop STO can be used to adjust the amount of light entering the optical system 10. The position of the aperture stop STO can 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 stop STO may be located between any two lenses, or on the object side of the first lens L1, or on the image side of the eighth lens L8; this embodiment does not limit this.

[0044] See Figure 3 In one possible implementation, the optical system 10 further includes an infrared cut-off filter IR, which can be an infrared bandpass filter IR, or a dual-pass filter IR. In this application, an infrared cut-off filter IR is selected to filter out infrared light, allowing only visible light to pass through, making the imaging more consistent with the visual experience of the human eye. Of course, an infrared bandpass filter IR can also be selected, which is fixedly set relative to each lens in the optical system 10. The infrared bandpass filter IR is used to allow infrared light of the center wavelength to pass through, and has the function of filtering out background stray light, and is used for infrared lenses. In addition, a dual-pass filter IR can also be selected, which can simultaneously transmit high levels of visible light and transmit part of the infrared light, thereby achieving different wavelength selection, enabling both visible light imaging and infrared imaging, thus achieving day and night usability. The filter IR can be assembled together with each lens as part of the optical system 10. In other embodiments, the filter IR can also be a component independent of the optical system 10. The filter IR can be installed between the optical system 10 and the photosensitive chip during the assembly of the optical system 10 and the photosensitive chip. It is understood that the filter IR can be made of optical glass coating, colored glass, or other materials, and can be selected according to actual needs. This embodiment does not impose specific limitations. In other embodiments, the filtering function can also be achieved by providing a filter coating on at least one of the first to eighth lenses.

[0045] See Figure 3At least one lens in the optical system 10 can have a spherical surface. A spherical surface design reduces the difficulty and cost of lens fabrication. In some embodiments, at least one lens in the optical system 10 can also have an aspherical surface. A lens is said to have an aspherical surface when at least one surface (object-side or image-side) is aspherical. In some embodiments, both the object-side and image-side surfaces of each lens can be designed as aspherical. Aspherical design helps the optical system 10 more effectively eliminate aberrations and improve image quality. In some embodiments, to balance fabrication cost, fabrication difficulty, image quality, and assembly difficulty, the surface design of each lens in the optical system 10 can be a combination of spherical and aspherical surfaces. In this application, the sixth lens L6 has an aspherical surface, while the first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, seventh lens L7, and eighth lens L8 have spherical surfaces.

[0046] See Figure 3 In this embodiment, the optical system 10 can satisfy the relationship: 25deg≤FOV≤30deg, where FOV is the maximum field of view of the optical system 10. By making the optical system 10 satisfy the above relationship, the optical system 10 can obtain a longer focal length while avoiding the introduction of excessive aberrations, and it is also beneficial for the optical system 10 to obtain a sufficient field of view.

[0047] See Figure 3 In this embodiment, the optical system 10 satisfies the relationship: 1.5 ≤ FNO ≤ 1.75, where FNO is the aperture number of the optical system. By satisfying this relationship, a smaller aperture number allows the optical system 10 to have a larger aperture, which is beneficial for the optical system 10 to collect more light flux per unit time, resulting in a brighter image with less noise under low light conditions. Furthermore, the optical system 10 can achieve a shallow depth of field by blurring the background to highlight the subject. The combination of a medium field of view and a small aperture number allows the optical system 10 to achieve clear imaging at a distance while simultaneously highlighting the subject.

[0048] In summary, combining Figure 1 , Figure 2 and Figure 3 As shown, this embodiment of the application enables the optical system 10 to have both a long focal length and a large aperture, which can achieve clear imaging at a distance while obtaining a shallow depth of field by blurring the background to highlight the subject and form a high-quality image.

[0049] The optical system 10 of this application embodiment will now be described in detail with reference to specific parameters.

[0050] First embodiment, Figure 3yes Figure 2 A schematic diagram of the structure of the optical system 10 in the diagram; Figure 4 yes Figure 3 The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system 10 in the image. Combined with... Figure 3 and Figure 4 As shown, the optical system 10 of this embodiment includes, along the optical axis O from the object side to the image side, the following components in sequence: a first lens L1, having positive refractive power, wherein the object side S1 of the first lens L1 is convex near the optical axis O, and the image side S2 is concave near the optical axis O; a second lens L2, having positive refractive power, wherein the object side S3 of the second lens L2 is convex near the optical axis O, and the image side S4 of the second lens L2 is convex near the optical axis O; a third lens L3, having negative refractive power, wherein the object side S5 of the third lens L3 is concave near the optical axis O, and the image side S6 is concave near the optical axis O; and a fourth lens L4, having negative refractive power, wherein the object side S7 of the fourth lens is concave near the optical axis O, and the image side S8 of the fourth lens L4 is concave near the optical axis O. The fifth lens L5 has positive refractive power. Its object-side surface S9 is convex near the optical axis O, and its image-side surface S10 is also convex near the optical axis O. The sixth lens L6 has positive refractive power. Its object-side surface S11 is convex near the optical axis O, and its image-side surface S12 is also convex near the optical axis O. The seventh lens L7 has positive refractive power. Its object-side surface S13 is convex near the optical axis O, and its image-side surface S14 is also convex near the optical axis O. The eighth lens L8 has negative refractive power. Its object-side surface S15 is concave near the optical axis O, and its image-side surface S16 is convex near the optical axis O.

[0051] The materials of the first lens L1 to the eighth lens L8 are not limited; for example, they can all be glass.

[0052] In addition, the optical system 10 also includes an aperture stop STO and a filter IR. The aperture stop STO is disposed on the side of the third lens L3 away from the second lens L2 and is used to control the amount of light entering the lens. In other embodiments, the aperture stop STO can also be disposed between any two adjacent lenses; or, the aperture stop STO can also be disposed on the object side of the first lens L1; or, the aperture stop STO can also be disposed on the image side of the eighth lens L8. The filter IR is disposed on the image side of the eighth lens L8. The filter IR includes a surface S17 facing 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 with a wavelength of 380nm-780nm. The filter IR is made of glass and can be coated with a film.

[0053] Table 1a shows the parameters of the optical system 10 of this embodiment, where the Y-radius is the radius of curvature of the object-side or image-side surface of the corresponding surface number at the optical axis O. 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 along the optical axis, and the second value is the distance along the optical axis from the image-side surface to the next surface in the image-side direction. Focal length, material refractive index, and Abbe number are all obtained using visible light with a reference wavelength of 558 nm. The units for Y-radius, thickness, and effective focal length are all millimeters (mm). Table 1a

[0054] Where EFL is the effective focal length of optical system 10, denoted by F in the formula of optical system 10. FNO is the aperture number of optical system 10, FOV is the field of view of optical system 10, and IMGH is half the image height corresponding to the maximum field of view of optical system 10.

[0055] In this embodiment, both the object-side and image-side surfaces of the sixth lens L6 are aspherical. The surface shape x of the aspherical lens can be defined using the following aspherical formula:

[0056] Where x is the distance vector from the vertex of the aspherical surface at a height h along the optical axis; c is the paraxial curvature of the aspherical 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 i-th order correction coefficient of the aspherical surface. Table 1b gives the conic coefficient k, and the higher-order coefficients A4, A6, A8, A10, A12, A14 and A16 that can be used for the aspherical mirrors S11-S12 in the first embodiment.

[0057] Table 1b

[0058] Figure 4 Figure (a) shows the longitudinal spherical aberration curves of the optical system 10 of the first embodiment at wavelengths of 415.0000 nm, 435.0000 nm, 455.0000 nm, 502.0000 nm, 558.0000 nm, 614.0000 nm, and 661.0000 nm. The horizontal axis along the X-axis represents the focal point shift, i.e., the distance (in mm) from the imaging plane to the intersection of the light ray and the optical axis. The vertical axis along the Y-axis represents the normalized field of view. The longitudinal spherical aberration curves represent the deviation of the converging focal point of light rays of different wavelengths after passing through the lenses of the optical system 10. Figure 4As can be seen in (a), the convergence focus of each wavelength of light in the first embodiment tends to be consistent, and the blur spots or color halos in the image are effectively suppressed, indicating that the imaging quality of the optical system 10 in this embodiment is good.

[0059] Figure 4 Figure (b) also shows an astigmatism curve of the optical system 10 of the first embodiment at a wavelength of 558.0000 nm, where the horizontal axis along the X-axis represents the focus shift and the vertical axis along the Y-axis represents the field of view, both in degrees. The X-curve in the astigmatism curve represents the sagittal field curvature at 558.0000 nm, and the Y-curve represents the meridional field curvature at 558.0000 nm. Figure 4 As can be seen in (b), the field curvature of the optical system 10 is small, and the field curvature and astigmatism of each field of view are well corrected, with clear imaging at both the center and the edge of the field of view.

[0060] Figure 4 Image (c) also shows the distortion curve of the optical system 10 of the first embodiment at a wavelength of 558.0000 nm. The horizontal axis along the X-axis represents the distortion value in %, and the vertical axis along the Y-axis represents the field of view in degrees. The distortion curve represents the distortion magnitude corresponding to different field of view angles. Figure 4 As can be seen in (c), at a wavelength of 558.0000nm, the image distortion caused by the main beam is small, and the imaging quality of the system is excellent.

[0061] 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 smaller aberrations, better imaging quality, and good imaging performance.

[0062] Second embodiment, Figure 5 This is a schematic diagram of the optical system 10 according to the second embodiment. Figure 6 yes Figure 5 The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system 10 are shown in the figure. Please refer to... 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 plane at the near optical axis O.

[0063] The first lens L1 to the eighth lens L8 mentioned above are all made of glass.

[0064] In addition, the optical system 10 also includes an aperture stop STO, a filter IR, and a protective glass CG. The aperture stop STO is disposed on the side of the third lens L3 away from the second lens L2 and is used to control the amount of light entering the lens. In other embodiments, the aperture stop STO may also be disposed between two adjacent lenses or on other lenses. The filter IR is disposed 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 with a wavelength of 380nm-780nm. The filter IR is made of glass and may be coated. The protective glass CG is disposed on the image side of the filter IR and is used to protect the other lenses of the optical system 10 from damage by the external environment.

[0065] Table 2a shows the parameters of the optical system 10 in this embodiment. The focal length, material refractive index and Abbe number are obtained using visible light with a reference wavelength of 558 nm. The units for Y radius, thickness and effective focal length are millimeters (mm). The meanings of the other parameters are the same as those in the first embodiment.

[0066] Table 2a

[0067] The meanings of the parameters in Table 2a are the same as those in the first embodiment.

[0068] Table 2b gives 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.

[0069] Table 2b

[0070] Figure 6 (a) Figure 6 (b) Figure 6 Image (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 converging focal point of light rays of different wavelengths after passing through the lenses of the optical system 10; the astigmatism curve represents the meridional image plane curvature and the sagittal image plane curvature; and the distortion curve represents the distortion magnitude corresponding to different field of view angles. Figure 6 It can be seen that the longitudinal spherical aberration, field curvature and distortion of the optical system 10 are well controlled, thus the optical system 10 of the second embodiment has good imaging quality.

[0071] Third embodiment, Figure 7 This is a schematic 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 are shown in the figure. Please refer to... Figure 7 and Figure 8 The refractive power and surface design of each lens in the optical system 10 of the third embodiment are the same as those in the optical system 10 of the first embodiment.

[0072] Table 3a shows the parameters of the optical system 10 in this embodiment. The focal length, material refractive index and Abbe number are obtained using visible light with a reference wavelength of 558 nm. The units for Y radius, thickness and effective focal length are millimeters (mm). The meanings of the other parameters are the same as those in the first embodiment.

[0073] Table 3a

[0074] The meanings of the parameters in Table 3a are the same as those in the first embodiment.

[0075] Table 3b gives 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] Figure 8 (a) Figure 8 (b) Figure 8 Image (c) shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system 10 according to the third embodiment. The longitudinal spherical aberration curve represents the deviation of the converging focal point of light rays of different wavelengths after passing through the lenses of the optical system 10; the astigmatism curve represents the meridional image plane curvature and the sagittal image plane curvature; and the distortion curve represents the distortion magnitude corresponding to different field of view angles. Figure 8 It can be seen that the longitudinal spherical aberration, field curvature and distortion of the optical system 10 are well controlled, and the optical system 10 of the third embodiment can achieve good imaging quality.

[0078] Fourth embodiment, Figure 9 This is a schematic 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 are shown in the figure. Please refer to... Figure 9 and Figure 10The difference between the optical system 10 of the fourth embodiment and the optical system 10 of the first embodiment is that the image-side surface S4 of the second lens L2 of the optical system 10 of the fourth embodiment is concave near the optical axis O, the object-side surface S5 of the third lens L3 is convex near the optical axis O, and the image-side surface S14 of the seventh lens L7 is concave near the optical axis O.

[0079] Table 4a shows the parameters of the optical system 10 in this embodiment. The focal length, material refractive index and Abbe number are obtained using visible light with a reference wavelength of 558 nm. The units for Y radius, thickness and effective focal length are millimeters (mm). The meanings of the other parameters are the same as those in the first embodiment.

[0080] Table 4a

[0081] The meanings of the parameters in Table 4a are the same as those in the first embodiment.

[0082] Table 4b gives 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.

[0083] Table 4b

[0084] Figure 10 (a) Figure 10 (b) Figure 10 Image (c) shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system 10 according to the fourth embodiment. The longitudinal spherical aberration curve represents the deviation of the converging focal point of light rays of different wavelengths after passing through the lenses of the optical system 10; the astigmatism curve represents the meridional and sagittal image plane curvature; and the distortion curve represents the distortion magnitude corresponding to different field of view angles. Figure 10 It can be seen that the longitudinal spherical aberration, field curvature and distortion of the optical system 10 are well controlled, and the optical system 10 of the fourth embodiment can achieve good imaging quality.

[0085] Fifth embodiment, Figure 11 This is a schematic 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 are shown in the figure. Please refer to... 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 at the near optical axis O.

[0086] Table 5a shows the parameters of the optical system 10 in this embodiment. The focal length, material refractive index and Abbe number are obtained using visible light with a reference wavelength of 558 nm. The units for Y radius, thickness and effective focal length are millimeters (mm). The meanings of the other parameters are the same as those in the first embodiment.

[0087] Table 5a

[0088] The meanings of the parameters in Table 5a are the same as those in the first embodiment.

[0089] Table 5b gives 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.

[0090] Table 5b

[0091] Figure 12 (a) Figure 12 (b) Figure 12 Image (c) shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system 10 according to the fifth embodiment. The longitudinal spherical aberration curve represents the deviation of the converging focal point of light rays of different wavelengths after passing through the lenses of the optical system 10; the astigmatism curve represents the meridional image plane curvature and the sagittal image plane curvature; and the distortion curve represents the distortion magnitude corresponding to different field of view angles. Figure 12 It can be seen that the longitudinal spherical aberration, field curvature and distortion of the optical system 10 are well controlled, and the optical system 10 of the fifth embodiment can achieve good imaging quality.

[0092] Sixth embodiment, Figure 13 This is a schematic 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 are shown in the figure. Please refer to... Figure 13 and Figure 14 The difference between the optical system 10 of the sixth 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 sixth embodiment is a plane at the near optical axis O.

[0093] Table 6a shows the parameters of the optical system 10 in this embodiment. The focal length, material refractive index and Abbe number are obtained using visible light with a reference wavelength of 558 nm. The units for Y radius, thickness and effective focal length are millimeters (mm). The meanings of the other parameters are the same as those in the first embodiment.

[0094] Table 6a

[0095] The meanings of the parameters in Table 6a are the same as those in the first embodiment.

[0096] Table 6b gives 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.

[0097] Table 6b

[0098] Figure 14 (a) Figure 14 (b) Figure 14 Image (c) shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system 10 according to the sixth embodiment. The longitudinal spherical aberration curve represents the deviation of the converging focal point of light rays of different wavelengths after passing through the lenses of the optical system 10; the astigmatism curve represents the meridional and sagittal image plane curvature; and the distortion curve represents the distortion magnitude corresponding to different field of view angles. Figure 14 It can be seen that the longitudinal spherical aberration, field curvature and distortion of the optical system 10 are well controlled, and the optical system 10 of the sixth embodiment can achieve good imaging quality.

[0099] Seventh embodiment, Figure 15 This is a schematic 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 are shown in the figure. Please refer to... 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 of the optical system 10 of the seventh embodiment is concave at the near optical axis O.

[0100] Table 7a shows the parameters of the optical system 10 in this embodiment. The focal length, material refractive index and Abbe number are obtained using visible light with a reference wavelength of 558 nm. The units for Y radius, thickness and effective focal length are millimeters (mm). The meanings of the other parameters are the same as those in the first embodiment.

[0101] Table 7a

[0102] The meanings of the parameters in Table 7a are the same as those in the first embodiment.

[0103] Table 7b gives the higher-order coefficients that can be used for each aspherical mirror in the seventh embodiment, wherein each aspherical surface shape can be defined by the formula given in the first embodiment.

[0104] Table 7b

[0105] Figure 16 (a) Figure 16 (b) Figure 16 Image (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 converging focal point of light rays of different wavelengths after passing through the lenses of the optical system 10; the astigmatism curve represents the meridional image plane curvature and the sagittal image plane curvature; and the distortion curve represents the distortion magnitude corresponding to different field of view angles. Figure 16 It can be seen that the longitudinal spherical aberration, field curvature and distortion of the optical system 10 are well controlled, and the optical system 10 of the seventh embodiment can achieve good imaging quality.

[0106] Table 8 lists 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, and F / BFL of the optical systems in the first to seventh embodiments. The values ​​of ∑CT / ∑AT, F / F3, F6 / F, F7 / F, F8 / F, |R4 / R3|, |R5 / R6|, R10 / R9, R12 / R11, F2 / CT2, F3 / CT3, F4 / CT4, F5 / CT5, F6 / CT6, F7 / CT7, and F8 / CT8 are given, 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 on the optical axis from the object side of the first lens to the imaging plane of the optical system, IMGH is half the image height corresponding to the maximum field of view of the optical system, and F is the optical system's... The effective focal lengths are: F2 for the second lens, F3 for the third lens, F4 for the fourth lens, F5 for the fifth lens, F6 for the sixth lens, F7 for the seventh lens, F8 for the eighth lens, F45 for the combined focal length of the fourth and fifth lenses, SD1 for half the maximum effective aperture of the object-side surface of the first lens, SD12 for half the maximum effective aperture of the image-side surface of the sixth lens, SD13 for half the maximum effective aperture of the object-side surface of the seventh lens, and SD16 for the image-side surface of the eighth lens. R1 is half the maximum effective aperture of the lens, R2 is the radius of curvature of the object 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, R8 is the radius of curvature of the image side of the fourth lens at the optical axis, and R9 is half the radius of curvature of the object side 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 of the image-side surface of the fourth lens at its 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; and CT5 is the thickness of the fifth lens on the optical axis.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 on the optical axis of the first to eighth lenses.

[0107] Table 8

[0108] As shown in 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.

[0109] The technical features of the above embodiments can be combined in any way. For the sake of brevity, 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, they should be considered to be within the scope of this specification.

[0110] The above embodiments are merely illustrative of several implementation methods of this application, and their descriptions are relatively specific and detailed. However, they should not be construed as limiting the scope of this application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this application should be determined by the appended claims.

Claims

1. An optical system characterized by comprising: The refractive lens consists of eight elements, arranged sequentially along the optical axis from the object side to the image side: The first lens has positive refractive power. The object side of the first lens is convex near the optical axis, and the image side of the first lens is concave near the optical axis. The second lens has positive refractive power, and the object side of the second lens is convex near the optical axis; The third lens has negative refractive power, and the image side of the third lens is concave near the optical axis; The fourth lens has negative refractive power. The object side of the fourth lens is concave near the optical axis, and the image side of the fourth lens is concave near the optical axis. The fifth lens has positive refractive power. The object-side surface of the fifth lens is convex near the optical axis, and the image-side surface of the fifth lens is convex near the optical axis. The sixth lens has positive refractive power. The object-side surface of the sixth lens is convex near the optical axis, and the image-side surface of the sixth lens is convex near the optical axis. The seventh lens has positive refractive power, and the object-side surface of the seventh lens is convex near the optical axis; The eighth lens has negative refractive power. The object-side surface of the eighth lens is concave near the optical axis, and the image-side surface of the eighth lens is convex near the optical axis. The optical system satisfies the following relationships: 25deg≤FOV≤30deg, 1.5≤FNO≤1.75, 1.59≤TTL / F≤1.66; Wherein, 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 surface of the optical system on the optical axis, and F is the effective focal length of the optical system.

2. The optical system of claim 1, wherein The optical system satisfies the following relationship: 6.2≤TTL / IMGH≤7.2; and / or, 16.5deg≤FOV / FNO≤17.9deg; Wherein, TTL is the distance from the object side 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 the image height corresponding to the maximum field of view of the optical system.

3. The optical system of claim 1, wherein The optical system satisfies the following 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; Wherein, 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 and fifth lenses, and F is the effective focal length of the optical system.

4. The optical system of claim 1, wherein The optical system satisfies the following relationship: 1.2 ≤ SD1 / IMGH ≤ 1.65; and / or, 0.9 ≤ SD13 / SD12 ≤ 1.1; and / or, 1.3≤SD1 / SD16≤1.7; Wherein, 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, and IMGH is half of the image height corresponding to the maximum field of view of the optical system.

5. The optical system of claim 1, wherein, The optical system satisfies the following 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 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, R7 is the radius of curvature of the object side of the fourth lens at the optical axis, R8 is the radius of curvature of the image side of the fourth lens at the optical axis, R15 is the radius of curvature of the object side of the eighth lens at the optical axis, and R16 is the radius of curvature of the image side of the eighth lens at the optical axis.

6. The optical system of claim 1, wherein, The optical system satisfies the following relationship: 0.3≤SAG8 / CT4≤2; and / or, 2.1≤CT2 / ET2≤3; and / or, 3.1≤CT2 / CT3≤3.95; Wherein, SAG8 is the sag of the image side 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 of claim 1, wherein The optical system satisfies the following relationship: 2.4≤CT34 / CT3≤4.7; and / or, 0.8 ≤ CT78 / CT7 ≤ 3.5; and / or, 0.28≤CT67 / CT7≤1.3; Wherein, 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 of claim 1, wherein, The optical system satisfies the following 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 of the eighth lens to the imaging surface 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 to the eighth lens on the optical axis.

9. An image capture module, comprising: It includes a lens barrel, an electronic photosensitive element, and an optical system as described in any one of claims 1-8, 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.

10. An electronic device, characterized in that, It includes a main body and the camera module as described in claim 9, wherein the camera module is disposed on the main body.

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