Optical systems, camera modules and electronic equipment

Abstract

The present invention provides an optical system, an imaging module, and an electronic device. The optical system sequentially includes, from the object side to the image side along the optical axis direction: a first lens group having a positive refractive power and including a first lens; a second lens group having a negative refractive power and including a second lens, a third lens, and a fourth lens; a third lens group having a positive refractive power and including a fifth lens, a sixth lens, a seventh lens, and an eighth lens; the distances between the first lens group, the second lens group, and the third lens group are adjustable so that the optical system is in the long focal length end, the medium focal length end, and the short focal length end, and the focal lengths of the optical system at the long focal length end, the medium focal length end, and the short focal length end are different; the optical system satisfies the conditional formula: -70 < fg2 / AT24 < -10, where fg2 is the focal length of the second lens group, and AT24 is the sum of the air intervals on the optical axis between adjacent lenses in the second lens group. The optical system of the present application meets the requirements of high pixels, large-range zoom, and miniaturization.

Description

Technical Field

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

[0002] In recent years, electronic devices equipped with multiple lenses have emerged. Such electronic devices achieve the effects of ultra-clear shooting, wide-angle shooting, and telephoto shooting by switching different lenses. Although the lens configuration of such electronic devices meets the user's photography needs in different scenarios, it will increase the lens cost, occupy the space of the electronic device, make the electronic device thicker and heavier, and affect the user experience. Moreover, in order to achieve the effect of high imaging quality, the number of lens elements also needs to be increased, and the increase in the number of lens elements also causes difficulties in realizing lens miniaturization. Therefore, the existing lenses cannot meet the requirements of high pixels, large-range zoom, and miniaturization at the same time. Summary of the Invention

[0003] The purpose of this application is to provide an optical system, a camera module, and an electronic device to solve the above technical problems.

[0004] The present invention provides an optical system, which sequentially includes, from the object side to the image side along the optical axis direction: a first lens group with positive refractive power, the first lens group includes a first lens; a second lens group with negative refractive power, the second lens group includes a second lens, a third lens, and a fourth lens; a third lens group with positive refractive power, the third lens group includes a fifth lens, a sixth lens, a seventh lens, and an eighth lens; the distances between the first lens group, the second lens group, and the third lens group are adjustable so that the optical system is in the telephoto end, the mid-focus end, and the short-focus end, and the focal lengths of the optical system in the telephoto end, the mid-focus end, and the short-focus end are different; the optical system satisfies the conditional formula: -70 < fg2 / AT24 < -10, where fg2 is the focal length of the second lens group, and AT24 is the sum of the air gaps on the optical axis between adjacent lenses in the second lens group. The optical system of this application meets the requirements of high pixels, large-range zoom, and miniaturization at the same time. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the focal length of the second lens group to the sum of the air gaps on the optical axis between adjacent lenses in the second lens group, it is beneficial to shorten the total length of the second lens group, and further shorten the overall optical length of the system; in addition, it is also beneficial to correct the aberration generated by the front and rear lens groups, so that the aberration correction of the entire optical system reaches a balance, thereby improving the imaging quality of the system.

[0005] In some embodiments, the optical system satisfies the conditional formula: fc / fd>1.3, wherein fc is the focal length of the optical system at the telephoto end, and fd is the focal length of the optical system at the short focal end. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the focal length at the telephoto end to the focal length at the short focal end, the optical system can obtain a higher zoom ratio, thereby achieving a wider range of shooting magnifications.

[0006] In some embodiments, the optical system further includes a filter, which is placed between the eighth lens and the imaging surface, and the optical system satisfies the conditional formula: TTL / (D1+D2+D3)<2.6, 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, D1 is the distance from the object side of the first lens to the image side of the second lens on the optical axis, D2 is the distance from the image side of the fourth lens to the object side of the fifth lens on the optical axis, and D3 is the distance from the image side of the filter to the imaging surface on the optical axis. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the total length of the optical system to the sum of the distance from the object side of the first lens to the image side of the second lens on the optical axis, the distance from the image side of the fourth lens to the object side of the fifth lens on the optical axis, and the distance from the image side of the filter to the imaging surface on the optical axis, it is beneficial to shorten the total length of the optical system and increase the zoom range.

[0007] In some embodiments, the optical system satisfies the conditional formula: (g1+g2+g3) / fd<0.9, wherein g1 is the distance from the object side of the first lens to the image side of the first lens on the optical axis, g2 is the distance from the object side of the second lens to the image side of the fourth lens on the optical axis, g3 is the distance from the object side of the fifth lens to the image side of the seventh lens on the optical axis, and fd is the focal length of the optical system at the short focal end. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the sum of the total lengths of each lens group to the focal length at the short focal end, it is beneficial to realize the miniaturization of the lens, and the zoom range of the optical system can be widened in the short focal direction.

[0008] In some embodiments, the optical system satisfies the conditional formula: FNOc / FNOd<1.6, where FNOc is the aperture number of the optical system at the long focal end, and FNOd is the aperture number of the optical system at the short focal end. When the optical system satisfies the above conditional formula, it can ensure that sufficient light flux can be obtained in both long focal and short focal conditions, thereby enabling the optical system to achieve high-definition imaging.

[0009] In some embodiments, the optical system satisfies the conditional formula: 1 < fg1 / fc < 8, where fg1 is the focal length of the first lens group and fc is the focal length of the optical system at the long focal end. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the focal length of the first lens group to the focal length at the long focal end, it is beneficial to obtain a wider zoom range in the long focal direction. At the same time, by assigning an appropriate optical power to the first lens group, it is beneficial to correct distortion and spherical aberration, and further improve the system resolution.

[0010] In some embodiments, the optical system satisfies the conditional formula: 0.8 < fg3 / |R15 - R16| < 1.5, where fg3 is the focal length of the third lens group, R15 is the curvature radius of the object side surface of the eighth lens on the optical axis, and R16 is the curvature radius of the image side surface of the eighth lens on the optical axis. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the focal length of the third lens group to the difference between the curvature radius of the object side surface of the eighth lens on the optical axis and the curvature radius of the image side surface of the eighth lens on the optical axis, the light can pass through the filter to the image plane at a more reasonable angle, and a higher relative illuminance can be obtained. In addition, it can avoid the object side surface and the image side surface of the eighth lens from being too curved, and the light deflection angle is too large, and the forming difficulty of the eighth lens can also be reduced during processing and manufacturing.

[0011] In some embodiments, the optical system satisfies the conditional formula: 1 < f3 / fg2 < 5, where f3 is the focal length of the third lens and fg2 is the focal length of the second lens group. When the optical system satisfies the above conditional formula, by assigning an appropriate optical power to the third lens, the total length of the second lens group can be effectively shortened, and the ability of the second lens group to correct the spherical aberration generated by the front and rear lens groups can be improved, thereby improving the imaging quality.

[0012] In some embodiments, the optical system satisfies the conditional formula: sdmax / sdmin < 1.55, where sdmax is the maximum value among the maximum effective radii of the object side surface and the image side surface of the first lens to the eighth lens, and sdmin is the minimum value among the maximum effective radii of the object side surface and the image side surface of the first lens to the eighth lens. When the optical system satisfies the above conditional formula, by controlling the ratio of the maximum value to the minimum value among the maximum effective radii of the object side surface and the image side surface of the first lens to the eighth lens, on the one hand, it is beneficial to ensure that the light is deflected within a reasonable range, and on the other hand, it helps to control the lens size within a reasonable range, improve the forming and processing stability of the imaging system, and reduce the sensitivity.

[0013] In some embodiments, the optical system satisfies the conditional formula: 1.2 < g2 / ∑etg2 < 1.8, where g2 is the distance from the object side surface of the second lens to the image side surface of the fourth lens on the optical axis, and ∑etg2 is the sum of the edge thicknesses of the lenses in the second lens group. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the total length of the second lens group to the total edge thickness of each lens, it is beneficial to shorten the total length of the optical system, realize the miniaturization feature of the imaging system. In addition, the center thickness and edge thickness of the lenses in the second lens group can be ensured to be uniform, reducing the processing and forming difficulty.

[0014] In some embodiments, the optical system satisfies the conditional formula: BFc / ImgH < 3.5, where BFc is the minimum axial distance from the image side surface of the eighth lens to the imaging surface when the optical system is at the telephoto end, and ImgH is half of the diagonal length of the effective pixel area of the imaging surface. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the back focal length to the semi-image height of the optical system, good matching with the electronic photosensitive chip can be ensured. In addition, it is also beneficial to realize the telephoto characteristic of the optical system.

[0015] In some embodiments, the optical system satisfies the conditional formula: 2.5 < sag82 / sag81 < 3.5, where sag81 is the sagitta at the maximum effective radius of the object side surface of the eighth lens, and sag82 is the sagitta at the maximum effective radius of the image side surface of the eighth lens. When the optical system satisfies the above conditional formula, by controlling the ratio of the sagittas at the maximum effective radii of the object side and image side surfaces of the eighth lens within a reasonable range, a reasonable surface shape can be obtained for the object side and image side of the eighth lens. On the one hand, the aberration generated by the front lens group can be corrected, and the light can be controlled to transition to the image surface with a small deflection angle. On the other hand, the processing difficulty of the eighth lens can be reduced.

[0016] The present invention provides an imaging module, including a lens barrel, an electronic photosensitive element, and the optical system as described above. The first lens to the eighth lens of the optical system are installed in the lens barrel, and the electronic photosensitive element is arranged on the image side of the optical system, and is used to convert the light of the object incident on the electronic photosensitive element through the first lens to the eighth lens into an electrical signal of an image. By installing the first lens to the eighth lens of the optical system in the imaging module and reasonably configuring the surface shape and refractive power of each lens from the first lens to the eighth lens, the imaging module can simultaneously meet the requirements of high pixel, large-range zoom, and miniaturization.

[0017] The present invention provides an electronic device, including a housing and the imaging module as described above, and the imaging module is arranged in the housing. By providing the above imaging module in the electronic device in this application, the electronic device can simultaneously meet the requirements of high pixel, large-range zoom, and miniaturization. Description of the Drawings

[0018] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0019] Figure 1a is a schematic structural diagram of the optical system of the first embodiment at a short focal end;

[0020] Figure 1b are the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the first embodiment at the short focal end;

[0021] Figure 1c is a schematic structural diagram of the optical system of the first embodiment at a mid-focus end;

[0022] Figure 1d are the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the first embodiment at the mid-focal end;

[0023] Figure 1e is a schematic structural diagram of the optical system of the first embodiment at a telephoto end;

[0024] Figure 1f are the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the first embodiment at the telephoto end;

[0025] Figure 2a is a schematic structural diagram of the optical system of the second embodiment at a short focal end;

[0026] Figure 2b are the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the second embodiment at the short focal end;

[0027] Figure 2c is a schematic structural diagram of the optical system of the second embodiment at a mid-focus end;

[0028] Figure 2d are the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the second embodiment at the mid-focal end;

[0029] Figure 2e is a schematic structural diagram of the optical system of the second embodiment at a telephoto end;

[0030] Figure 2f are the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the second embodiment at the telephoto end;

[0031] Figure 3ais a schematic structural diagram of the optical system of the third embodiment at a short focal end;

[0032] Figure 3b are the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the third embodiment at the short focal end;

[0033] Figure 3c is a schematic structural diagram of the optical system of the third embodiment at a mid-focus end;

[0034] Figure 3d are the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the third embodiment at the mid-focus end;

[0035] Figure 3e is a schematic structural diagram of the optical system of the third embodiment at the telephoto end;

[0036] Figure 3f are the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the third embodiment at the telephoto end;

[0037] Figure 4a is a schematic structural diagram of the optical system of the fourth embodiment at a short focal end;

[0038] Figure 4b are the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fourth embodiment at the short focal end;

[0039] Figure 4c is a schematic structural diagram of the optical system of the fourth embodiment at a mid-focus end;

[0040] Figure 4d are the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fourth embodiment at the mid-focal end;

[0041] Figure 4e is a schematic structural diagram of the optical system of the fourth embodiment at the telephoto end;

[0042] Figure 4f are the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fourth embodiment at the telephoto end;

[0043] Figure 5a is a schematic structural diagram of the optical system of the fifth embodiment at a short focal end;

[0044] Figure 5b are the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fifth embodiment at the short focal end;

[0045] Figure 5c is a schematic structural diagram of the optical system of the fifth embodiment at a mid-focus end;

[0046] Figure 5d are the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fifth embodiment at the mid-focal end;

[0047] Figure 5e is a schematic structural diagram of the optical system of the fifth embodiment at the telephoto end;

[0048] Figure 5f 1 and 2 are the longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fifth embodiment at the telephoto end. DETAILED DESCRIPTION

[0049] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0050] The embodiment of the present application provides a camera module, which includes a lens barrel, an electronic photosensitive element and an optical system provided by an embodiment of the present invention, wherein the first lens to the eighth lens of the optical system are installed in the lens barrel, and the electronic photosensitive element is arranged on the image side of the optical system, and is used to convert the light of the object incident on the electronic photosensitive element through the first lens to the eighth lens into an electrical signal of an image. The electronic photosensitive element can be a complementary metal oxide semiconductor (CMOS) or a charge-coupled device (CCD). The camera module can be an independent lens of a digital camera, or an imaging module integrated in an electronic device such as a smart phone. The present application can make the camera module meet the requirements of high pixel, wide range zoom and miniaturization at the same time by installing the first lens to the eighth lens of the optical system in the camera module and reasonably configuring the surface shape and refractive power of each lens of the first lens to the eighth lens.

[0051] The embodiment of the present application provides an electronic device, which includes a housing and a camera module provided by the embodiment of the present application. The camera module and the electronic photosensitive element are arranged in the housing. The electronic device can be a smart phone, a personal digital assistant (PDA), a tablet computer, a smart watch, a drone, an e-book reader, a driving recorder, a wearable device, etc. By setting a camera module in the electronic device, the present application can make the electronic device meet the requirements of high pixel, wide range zoom and miniaturization at the same time.

[0052] An embodiment of the present application provides an optical system, which sequentially includes, from the object side to the image side along the optical axis direction: a first lens group with positive refractive power, and the first lens group includes a first lens; a second lens group with negative refractive power, and the second lens group includes a second lens, a third lens, and a fourth lens; a third lens group with positive refractive power, and the third lens group includes a fifth lens, a sixth lens, a seventh lens, and an eighth lens. An air gap can be provided between any two adjacent lenses among the first lens to the eighth lens.

[0053] The distances between the first lens group, the second lens group, and the third lens group are adjustable so that the optical system is in the telephoto end, the mid - focal end, and the wide - angle end, and the focal lengths of the optical system in the telephoto end, the mid - focal end, and the wide - angle end are different.

[0054] By reasonably configuring the refractive powers of the first lens group, the second lens group, and the third lens group, and by reasonably configuring the distances between the first lens group, the second lens group, and the third lens group, the present application can enable the optical system to simultaneously meet the requirements of high pixels, large - range zoom, and miniaturization.

[0055] It can be understood that when zooming from the wide - angle end to the telephoto end position, the first lens group remains stationary with respect to the image plane, the distance between the first lens group and the second lens group increases, and the distance between the third lens group and the image plane also increases, and the optical system includes at least one aspherical plastic lens.

[0056] In a specific embodiment, the optical system satisfies the conditional formula: - 70 < fg2 / AT24 < - 10, where fg2 is the focal length of the second lens group, and AT24 is the sum of the air gaps on the optical axis between adjacent lenses in the second lens group. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the focal length of the second lens group to the sum of the air gaps on the optical axis between adjacent lenses in the second lens group, it is beneficial to shorten the total length of the second lens group, and further shorten the overall optical length of the system; in addition, it is also beneficial to correct the aberration generated by the front and rear lens groups, so that the aberration correction of the entire optical system reaches a balance, thereby improving the imaging quality of the system. When fg2 / AT24 ≤ - 70, the sum of the air gaps on the optical axis between adjacent lenses in the second lens group is too small, and the lenses are prone to collision, which is not conducive to processing and assembly. When fg2 / AT24 ≥ - 10, the negative refractive power borne by the second lens group is too large, which is not conducive to aberration correction and overall balance, and easily leads to a reduction in image quality.

[0057] In a specific embodiment, the optical system satisfies the conditional formula: fc / fd>1.3, wherein fc is the focal length of the optical system at the telephoto end, and fd is the focal length of the optical system at the short focal end. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the focal length at the telephoto end to the focal length at the short focal end, the optical system can obtain a higher zoom ratio, thereby achieving a wider range of shooting magnifications. When fc / fd≤1.3, the zoom range is too small, and it is impossible to provide users with a better shooting experience.

[0058] In a specific embodiment, the optical system further includes a filter, which is placed between the eighth lens and the imaging surface, and the optical system satisfies the conditional formula: TTL / (D1+D2+D3)<2.6, 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, D1 is the distance from the object side of the first lens to the image side of the second lens on the optical axis, D2 is the distance from the image side of the fourth lens to the object side of the fifth lens on the optical axis, and D3 is the distance from the image side of the filter to the imaging surface on the optical axis. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the total length of the optical system to the sum of the distance from the object side of the first lens to the image side of the second lens on the optical axis, the distance from the image side of the fourth lens to the object side of the fifth lens on the optical axis, and the distance from the image side of the filter to the imaging surface on the optical axis, it is beneficial to shorten the total length of the optical system and increase the zoom range. When TTL / (D1+D2+D3)≥2.6, the sum of the distance from the object side of the first lens to the image side of the second lens on the optical axis, the distance from the image side of the fourth lens to the object side of the fifth lens on the optical axis, and the distance from the image side of the filter to the imaging surface on the optical axis is too small, which is not conducive to lens assembly and increases the difficulty of the process.

[0059] In a specific embodiment, the optical system satisfies the conditional formula: (g1+g2+g3) / fd<0.9, wherein g1 is the distance from the object side of the first lens to the image side of the first lens on the optical axis, g2 is the distance from the object side of the second lens to the image side of the fourth lens on the optical axis, g3 is the distance from the object side of the fifth lens to the image side of the seventh lens on the optical axis, and fd is the focal length of the optical system at the short focal end. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the sum of the total lengths of each lens group to the focal length at the short focal end, it is beneficial to achieve lens miniaturization and widen the zoom range of the optical system in the short focal direction. When (g1+g2+g3) / fd≥0.9, the sum of the total lengths of each lens group is too large, which is not conducive to correcting aberrations and shortening the total length of the system.

[0060] In a specific embodiment, the optical system satisfies the conditional formula: FNOc / FNOd < 1.6, where FNOc is the f-number of the optical system at the telephoto end, and FNOd is the f-number of the optical system at the wide-angle end. When the optical system satisfies the above conditional formula, sufficient light flux can be ensured in both the telephoto and wide-angle cases, thereby enabling the optical system to achieve high-definition imaging. When FNOc / FNOd ≥ 1.6, the difference between the f-number at the telephoto end and the f-number at the wide-angle end is too large, which easily causes a significant difference in imaging quality during zoom shooting and reduces the user's photo-taking experience.

[0061] In a specific embodiment, the optical system satisfies the conditional formula: 1 < fg1 / fc < 8, where fg1 is the focal length of the first lens group, and fc is the focal length of the optical system at the telephoto end. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the focal length of the first lens group to the focal length at the telephoto end, it is beneficial to obtain a wider zoom range in the telephoto direction. At the same time, by assigning an appropriate optical power to the first lens group, it is beneficial to correct distortion and spherical aberration, and further improve the system resolution.

[0062] In a specific embodiment, the optical system satisfies the conditional formula: 0.8 < fg3 / |R15 - R16| < 1.5, where fg3 is the focal length of the third lens group, R15 is the curvature radius of the object side surface of the eighth lens on the optical axis, and R16 is the curvature radius of the image side surface of the eighth lens on the optical axis. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the focal length of the third lens group to the difference between the curvature radius of the object side surface of the eighth lens on the optical axis and the curvature radius of the image side surface of the eighth lens on the optical axis, the light can pass through the filter and reach the image plane at a more reasonable angle, and a higher relative illuminance can be obtained. In addition, it can avoid the object side surface and the image side surface of the eighth lens from being too curved, and the light deflection angle is too large, and the forming difficulty of the eighth lens can also be reduced during processing and manufacturing.

[0063] In a specific embodiment, the optical system satisfies the conditional formula: 1 < f3 / fg2 < 5, where f3 is the focal length of the third lens, and fg2 is the focal length of the second lens group. When the optical system satisfies the above conditional formula, by assigning an appropriate optical power to the third lens, the total length of the second lens group can be effectively shortened, and the ability of the second lens group to correct the spherical aberration generated by the front and rear lens groups can be improved, thereby improving the imaging quality.

[0064] In a specific embodiment, the optical system satisfies the conditional formula: sdmax / sdmin < 1.55, where sdmax is the maximum value among the maximum effective radii of the object side and the image side of the first lens to the eighth lens, and sdmin is the minimum value among the maximum effective radii of the object side and the image side of the first lens to the eighth lens. When the optical system satisfies the above conditional formula, by controlling the ratio of the maximum value to the minimum value among the maximum effective radii of the object side and the image side of the first lens to the eighth lens, on the one hand, it is beneficial to ensure that the light is deflected within a reasonable range, and on the other hand, it helps to control the lens size within a reasonable range, improve the forming and processing stability of the imaging system, and reduce the sensitivity. When sdmax / sdmin ≥ 1.55, the lens aperture distribution is uneven, which easily leads to an excessive light deflection angle and affects the imaging quality.

[0065] In a specific embodiment, the optical system satisfies the conditional formula: 1.2 < g2 / ∑etg2 < 1.8, where g2 is the distance on the optical axis from the object side of the second lens to the image side of the fourth lens, and ∑etg2 is the sum of the edge thicknesses of each lens in the second lens group. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the total length of the second lens group to the total edge thickness of each lens, it is beneficial to shorten the total length of the optical system, realize the miniaturization feature of the imaging system, and in addition, it can ensure the uniformity of the center thickness and the edge thickness of the lenses in the second lens group, and reduce the processing and forming difficulty. When g2 / ∑etg2 ≥ 1.8 or ≤ 1.2, the difference between the edge thickness and the center thickness of the lenses in the second lens group is too large, and the relatively thinner part is easily squeezed and damaged, finally resulting in material waste and image quality degradation.

[0066] In a specific embodiment, the optical system satisfies the conditional formula: BFc / ImgH < 3.5, where BFc is the minimum axial distance from the image side of the eighth lens to the imaging surface when the optical system is at the telephoto end, and ImgH is half of the diagonal length of the effective pixel area of the imaging surface. When the optical system satisfies the above conditional formula, by reasonably configuring the ratio of the back focus of the optical system to the half image height, it can ensure good matching with the electronic photosensitive chip, and in addition, it is also beneficial to realize the telephoto characteristic of the optical system.

[0067] In a specific embodiment, the optical system satisfies the conditional formula: 2.5 < sag82 / sag81 < 3.5, where sag81 is the sag at the maximum effective radius of the object side surface of the eighth lens, and sag82 is the sag at the maximum effective radius of the image side surface of the eighth lens. When the optical system satisfies the above conditional formula, by controlling the ratio of the sags at the maximum effective radii of the object side and the image side of the eighth lens within a reasonable range, a reasonable surface shape can be obtained on both the object side and the image side of the eighth lens. On the one hand, the aberration generated by the front lens group can be corrected, and the light can be controlled to transition to the image plane with a smaller deflection angle. On the other hand, the processing difficulty of the eighth lens can be reduced. When sag82 / sag81 ≥ 3.5, it is easy to cause the surface shape of the eighth lens to be too curved, increasing the forming processing difficulty; while when sag82 / sag81 ≤ 2.5, the surface shape is flat, which is not conducive to aberration correction, and the resolution will also be reduced accordingly.

[0068] First embodiment,

[0069] Please refer to Figure 1a-1f , the optical system of this embodiment sequentially includes, from the object side to the image side along the optical axis direction:

[0070] The first lens L1 has a positive refractive power. The object side surface S1 of the first lens L1 is convex near the optical axis, and the image side surface S2 is concave near the optical axis; the object side surface S1 of the first lens L1 is convex at the circumference, and the image side surface S2 is concave at the circumference.

[0071] The second lens L2 has a negative refractive power. The object side surface S3 of the second lens L2 is convex near the optical axis, and the image side surface S4 is concave near the optical axis; the object side surface S3 of the second lens L2 is convex at the circumference, and the image side surface S4 is concave at the circumference.

[0072] The third lens L3 has a negative refractive power. The object side surface S5 of the third lens L3 is convex near the optical axis, and the image side surface S6 is concave near the optical axis; the object side surface S5 of the third lens L3 is concave at the circumference, and the image side surface S6 is convex at the circumference.

[0073] The fourth lens L4 has a positive refractive power. The object side surface S7 of the fourth lens is convex near the optical axis, and the image side surface S8 is concave near the optical axis; the object side surface S7 of the fourth lens L4 is concave at the circumference, and the image side surface S8 is convex at the circumference.

[0074] The fifth lens L5 has a positive refractive power. The object side surface S9 of the fifth lens L5 is convex near the optical axis, and the image side surface S10 is convex near the optical axis; the object side surface S9 of the fifth lens L5 is convex at the circumference, and the image side surface S10 is convex at the circumference.

[0075] The sixth lens L6 has positive refractive power. The object-side surface S11 of the sixth lens is convex at the near optical axis, and the image-side surface S12 is convex at the near optical axis. The object-side surface S11 of the sixth lens L6 is convex at the circumference, and the image-side surface S12 is convex at the circumference.

[0076] The seventh lens L7 has negative refractive power. The object-side surface S13 of the seventh lens L7 is concave at the near optical axis, and the image-side surface S14 is concave at the near optical axis. The object-side surface S13 of the seventh lens L7 is concave at the circumference, and the image-side surface S14 is concave at the circumference.

[0077] The eighth lens L8 has positive refractive power. The object-side surface S15 of the eighth lens L8 is concave at the near optical axis, and the image-side surface S16 is convex at the near optical axis. The object-side surface S15 of the eighth lens L8 is concave at the circumference, and the image-side surface S16 is convex at the circumference.

[0078] The material of the first lens L1 to the eighth lens L8 is plastic or glass. At least one of the first lens L1 to the eighth lens L8 is made of plastic.

[0079] In addition, the optical system also includes an aperture STO, an infrared filter L9 and an image plane S19. The aperture STO is arranged between the fourth lens L4 and the fifth lens L5, and is used to control the amount of light entering. In other embodiments, the aperture STO can also be arranged between other adjacent lenses, or on other lenses. The infrared filter L9 is arranged on the image side of the eighth lens L8, and includes an object side surface S17 and an image side surface S18. The infrared filter L9 is used to filter out infrared light so that the light incident on the image plane S19 is visible light, and the wavelength of visible light is 380nm-780nm. The material of the infrared filter L9 is glass, and a film can be coated on the glass. The image plane S19 is the surface where the image of the object is formed after the light of the subject passes through the optical system.

[0080] Table 1a(1)-Table 1a(2) shows the characteristics of the optical system of this embodiment, and the units of Y radius, thickness and focal length are all millimeters (mm). The reference wavelength of the focal length is 555nm, and the reference wavelength of the refractive index and Abbe number is 587.56nm.

[0081] Table 1a(1)

[0082]

[0083]

[0084] Table 1a(2)

[0085] Variable distance D1 D2 D3 f(mm) FNO FOV(°) Short focus position 0.7500 8.1673 3.6999 12.9 2.90 17.8 Mid-focus position 3.0901 3.9459 5.5611 17.5 3.31 12.9 Telephoto position 3.7074 2.2386 6.6712 20.1 3.73 11.2

[0086] Wherein, f is the focal length of the optical system, FNO is the aperture number of the optical system, FOV is the field of view of the optical system, and TTL is the distance from the object side of the first lens to the imaging plane of the optical system on the optical axis.

[0087] In this embodiment, the object side surface and the image side surface of any one of the third lens L3, the fourth lens L4, the seventh lens L7 and the eighth lens L8 are aspherical surfaces, and the surface shape x of each aspherical lens can be defined by but not limited to the following aspherical surface formula:

[0088]

[0089] Wherein, x is the distance vector height from the vertex of the aspheric surface when the aspheric surface is 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(1) above); k is the cone coefficient; Ai is the correction coefficient of the i-th order of the aspheric surface. Table 1b shows the high-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 that can be used for each aspheric mirror surface S1-S14 in the first embodiment.

[0090] Table 1b

[0091]

[0092] Figure 1a A schematic structural diagram of the optical system of the first embodiment at the short focal end is shown. Figure 1b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the first embodiment at the short focal end are shown. The longitudinal spherical aberration curve indicates the deviation of the convergence point of light of different wavelengths after passing through each lens of the optical system; the astigmatism curve indicates the meridional image curvature and sagittal image curvature; and the distortion curve indicates the distortion magnitude value corresponding to different field angles. Figure 1b It can be seen that the optical system provided in the first embodiment can achieve good imaging quality.

[0093] Figure 1c A schematic structural diagram of the optical system of the first embodiment at the mid-focus end is shown. Figure 1d The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the first embodiment at the mid-focus end are shown. The longitudinal spherical aberration curve indicates the deviation of the convergence point of light of different wavelengths after passing through each lens of the optical system; the astigmatism curve indicates the meridional image curvature and sagittal image curvature; and the distortion curve indicates the distortion magnitude value corresponding to different field angles. Figure 1d It can be seen that the optical system provided in the first embodiment can achieve good imaging quality.

[0094] Figure 1eA schematic structural diagram of the optical system of the first embodiment at the telephoto end is shown. Figure 1f The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the first embodiment at the telephoto end are shown. The longitudinal spherical aberration curve indicates the deviation of the convergence point of light of different wavelengths after passing through each lens of the optical system; the astigmatism curve indicates the meridional image curvature and sagittal image curvature; and the distortion curve indicates the distortion magnitude value corresponding to different field angles. Figure 1f It can be seen that the optical system provided in the first embodiment can achieve good imaging quality.

[0095] Second embodiment,

[0096] Please refer to Figure 2a-2f The optical system of this embodiment includes, in order from the object side to the image side along the optical axis:

[0097] The first lens L1 has positive refractive power. The object-side surface S1 of the first lens L1 is convex at the near optical axis, and the image-side surface S2 is concave at the near optical axis. The object-side surface S1 of the first lens L1 is convex at the circumference, and the image-side surface S2 is concave at the circumference.

[0098] The second lens L2 has negative refractive power. The object-side surface S3 of the second lens L2 is concave at the near optical axis, and the image-side surface S4 is convex at the near optical axis. The object-side surface S3 of the second lens L2 is concave at the circumference, and the image-side surface S4 is convex at the circumference.

[0099] The third lens L3 has negative refractive power. The object-side surface S5 of the third lens L3 is convex at the near optical axis, and the image-side surface S6 is concave at the near optical axis. The object-side surface S5 of the third lens L3 is concave at the circumference, and the image-side surface S6 is concave at the circumference.

[0100] The fourth lens L4 has positive refractive power. The object-side surface S7 of the fourth lens L4 is convex at the near optical axis, and the image-side surface S8 is concave at the near optical axis. The object-side surface S7 of the fourth lens L4 is convex at the circumference, and the image-side surface S8 is concave at the circumference.

[0101] The fifth lens L5 has positive refractive power. The object-side surface S9 of the fifth lens L5 is convex at the near optical axis, and the image-side surface S10 is convex at the near optical axis. The object-side surface S9 of the fifth lens L5 is convex at the circumference, and the image-side surface S10 is convex at the circumference.

[0102] The sixth lens L6 has positive refractive power. The object-side surface S11 of the sixth lens is convex at the near optical axis, and the image-side surface S12 is convex at the near optical axis. The object-side surface S11 of the sixth lens L6 is convex at the circumference, and the image-side surface S12 is convex at the circumference.

[0103] The seventh lens L7 has negative refractive power. The object-side surface S13 of the seventh lens L7 is convex at the near optical axis, and the image-side surface S14 is concave at the near optical axis. The object-side surface S13 of the seventh lens L7 is concave at the circumference, and the image-side surface S14 is concave at the circumference.

[0104] The eighth lens L8 has positive refractive power. The object-side surface S15 of the eighth lens L8 is concave at the near optical axis, and the image-side surface S16 is convex at the near optical axis. The object-side surface S15 of the eighth lens L8 is convex at the circumference, and the image-side surface S16 is convex at the circumference.

[0105] The other structures of the second embodiment are the same as those of the first embodiment, and can be used as a reference.

[0106] Table 2a(1)-Table 2a(2) shows the characteristics of the optical system of this embodiment, and the units of Y radius, thickness and focal length are all millimeters (mm). The reference wavelength of the focal length is 555nm, and the reference wavelength of the refractive index and Abbe number is 587.56nm.

[0107] Table 2a(1)

[0108]

[0109] Table 2a(2)

[0110] Variable distance D1 D2 D3 f(mm) FNO FOV(°) Short focus position 0.9000 7.3600 4.4420 14.2 2.87 16.1 Mid-focus position 3.9610 2.9153 5.8256 18.0 3.45 12.4 Telephoto position 4.7483 1.5324 6.4113 19.6 3.73 11.4

[0111] The meanings of the parameters in Table 2a(1)-Table 2a(2) are the same as those in the first embodiment.

[0112] Table 2b gives the coefficients of the higher-order terms that can be used for each aspherical mirror surface in the second embodiment, wherein each aspherical surface shape can be defined by the formula given in the first embodiment.

[0113] Table 2b

[0114]

[0115] Figure 2a A schematic structural diagram of the optical system of the second embodiment at the short focal end is shown. Figure 2b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the second embodiment at the short focal end are shown. Figure 2b It can be seen that the optical system provided in the second embodiment can achieve good imaging quality.

[0116] Figure 2c A schematic structural diagram of the optical system of the second embodiment at the mid-focus end is shown. Figure 2d The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the second embodiment at the mid-focus end are shown. Figure 2dIt can be seen that the optical system provided in the second embodiment can achieve good imaging quality.

[0117] Figure 2e A schematic structural diagram of the optical system of the second embodiment at the telephoto end is shown. Figure 2f The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the second embodiment at the telephoto end are shown. Figure 2f It can be seen that the optical system provided in the second embodiment can achieve good imaging quality.

[0118] The third embodiment,

[0119] Please refer to Figure 3a-3f The optical system of this embodiment includes, in order from the object side to the image side along the optical axis:

[0120] The first lens L1 has positive refractive power. The object-side surface S1 of the first lens L1 is convex at the near optical axis, and the image-side surface S2 is concave at the near optical axis. The object-side surface S1 of the first lens L1 is convex at the circumference, and the image-side surface S2 is concave at the circumference.

[0121] The second lens L2 has negative refractive power. The object-side surface S3 of the second lens L2 is convex at the near optical axis, and the image-side surface S4 is concave at the near optical axis. The object-side surface S3 of the second lens L2 is convex at the circumference, and the image-side surface S4 is concave at the circumference.

[0122] The third lens L3 has negative refractive power. The object-side surface S1 of the third lens L3 is convex at the near optical axis, and the image-side surface S2 is concave at the near optical axis. The object-side surface S5 of the third lens L3 is concave at the circumference, and the image-side surface S6 is convex at the circumference.

[0123] The fourth lens L4 has positive refractive power. The object-side surface S7 of the fourth lens L4 is convex at the near optical axis, and the image-side surface S8 is convex at the near optical axis. The object-side surface S7 of the fourth lens L4 is concave at the circumference, and the image-side surface S8 is convex at the circumference.

[0124] The fifth lens L5 has positive refractive power. The object-side surface S9 of the fifth lens L5 is convex at the near optical axis, and the image-side surface S10 is convex at the near optical axis. The object-side surface S9 of the fifth lens L5 is convex at the circumference, and the image-side surface S10 is convex at the circumference.

[0125] The sixth lens L6 has positive refractive power. The object-side surface S11 of the sixth lens is convex at the near optical axis, and the image-side surface S12 is convex at the near optical axis. The object-side surface S11 of the sixth lens L6 is convex at the circumference, and the image-side surface S12 is convex at the circumference.

[0126] The seventh lens L7 has negative refractive power. The object-side surface S13 of the seventh lens L7 is convex at the near optical axis, and the image-side surface S14 is concave at the near optical axis. The object-side surface S13 of the seventh lens L7 is concave at the circumference, and the image-side surface S14 is concave at the circumference.

[0127] The eighth lens L8 has positive refractive power. The object-side surface S15 of the eighth lens L8 is concave at the near optical axis, and the image-side surface S16 is convex at the near optical axis. The object-side surface S15 of the eighth lens L8 is concave at the circumference, and the image-side surface S16 is convex at the circumference.

[0128] The other structures of the third embodiment are the same as those of the first embodiment, and can be used as a reference.

[0129] Table 3a(1)-Table 3a(2) shows the characteristics of the optical system of this embodiment, and the units of Y radius, thickness and focal length are all millimeters (mm). The reference wavelength of the focal length is 555nm, and the reference wavelength of the refractive index and Abbe number is 587.56nm.

[0130] Table 3a(1)

[0131]

[0132]

[0133] Table 3a(2)

[0134] Variable distance D1 D2 D3 f(mm) FNO FOV(°) Short focus position 0.6348 11.9841 3.6089 11.8 3.09 19.5 Mid-focus position 5.3441 5.1407 5.7530 18.5 3.45 12.2 Telephoto position 7.4518 0.0500 8.7260 27 4.65 8.3

[0135] The meanings of the parameters in Table 3a(1)-Table 3a(2) are the same as those in the first embodiment.

[0136] Table 3b gives the coefficients of the higher-order terms that can be used for each aspherical mirror surface in the third embodiment, wherein each aspherical surface shape can be defined by the formula given in the first embodiment.

[0137] Table 3b

[0138]

[0139] Figure 3a A schematic structural diagram of the optical system of the third embodiment at the short focal end is shown. Figure 3b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the third embodiment at the short focal end are shown. Figure 3b It can be seen that the optical system provided in the third embodiment can achieve good imaging quality.

[0140] Figure 3c A schematic structural diagram of the optical system of the third embodiment at the mid-focus end is shown. Figure 3dThe longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the third embodiment at the mid-focus end are shown. Figure 3d It can be seen that the optical system provided in the third embodiment can achieve good imaging quality.

[0141] Figure 3e A schematic structural diagram of the optical system of the third embodiment at the telephoto end is shown. Figure 3f The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the third embodiment at the telephoto end are shown. Figure 3f It can be seen that the optical system provided in the third embodiment can achieve good imaging quality.

[0142] Fourth embodiment,

[0143] Please refer to Figure 4a-4f The optical system of this embodiment includes, in order from the object side to the image side along the optical axis:

[0144] The first lens L1 has positive refractive power. The object-side surface S1 of the first lens L1 is convex at the near optical axis, and the image-side surface S2 is concave at the near optical axis. The object-side surface S1 of the first lens L1 is convex at the circumference, and the image-side surface S2 is concave at the circumference.

[0145] The second lens L2 has negative refractive power. The object-side surface S3 of the second lens L2 is convex at the near optical axis, and the image-side surface S4 is concave at the near optical axis. The object-side surface S3 of the second lens L2 is convex at the circumference, and the image-side surface S4 is concave at the circumference.

[0146] The third lens L3 has negative refractive power. The object-side surface S1 of the third lens L3 is convex at the near optical axis, and the image-side surface S2 is concave at the near optical axis. The object-side surface S5 of the third lens L3 is concave at the circumference, and the image-side surface S6 is convex at the circumference.

[0147] The fourth lens L4 has positive refractive power. The object-side surface S7 of the fourth lens L4 is convex at the near optical axis, and the image-side surface S8 is convex at the near optical axis. The object-side surface S7 of the fourth lens L4 is concave at the circumference, and the image-side surface S8 is convex at the circumference.

[0148] The fifth lens L5 has positive refractive power. The object-side surface S9 of the fifth lens L5 is convex at the near optical axis, and the image-side surface S10 is convex at the near optical axis. The object-side surface S9 of the fifth lens L5 is convex at the circumference, and the image-side surface S10 is convex at the circumference.

[0149] The sixth lens L6 has positive refractive power. The object-side surface S11 of the sixth lens is convex at the near optical axis, and the image-side surface S12 is convex at the near optical axis. The object-side surface S11 of the sixth lens L6 is convex at the circumference, and the image-side surface S12 is convex at the circumference.

[0150] The seventh lens L7 has negative refractive power. The object-side surface S13 of the seventh lens L7 is concave at the near optical axis, and the image-side surface S14 is concave at the near optical axis. The object-side surface S13 of the seventh lens L7 is concave at the circumference, and the image-side surface S14 is concave at the circumference.

[0151] The eighth lens L8 has positive refractive power. The object-side surface S15 of the eighth lens L8 is concave at the near optical axis, and the image-side surface S16 is convex at the near optical axis. The object-side surface S15 of the eighth lens L8 is concave at the circumference, and the image-side surface S16 is convex at the circumference.

[0152] The other structures of the fourth embodiment are the same as those of the first embodiment, and can be referred to herein.

[0153] Table 4a(1)-Table 4a(2) shows the characteristics of the optical system of this embodiment, and the units of Y radius, thickness and focal length are all millimeters (mm). The reference wavelength of the focal length is 555nm, and the reference wavelength of the refractive index and Abbe number is 587.56nm.

[0154] Table 4a(1)

[0155]

[0156]

[0157] Table 4a(2)

[0158] Variable distance D1 D2 D3 f(mm) FNO FOV(°) Short focus position 0.7500 9.4015 3.7999 12.2 2.98 18.8 Mid-focus position 4.0350 4.3163 5.5999 17.0 3.29 13.3 Telephoto position 5.6000 0.3005 8.0509 23 4.29 9.8

[0159] The meanings of the parameters in Table 4a(1)-Table 4a(2) are the same as those in the first embodiment.

[0160] Table 4b gives the coefficients of the higher-order terms that can be used for each aspherical mirror surface in the fourth embodiment, wherein each aspherical surface shape can be defined by the formula given in the first embodiment.

[0161] Table 4b

[0162]

[0163] Figure 4a A schematic structural diagram of the optical system of the fourth embodiment at the short focal end is shown. Figure 4b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fourth embodiment at the short focal end are shown. Figure 4b It can be seen that the optical system provided in the fourth embodiment can achieve good imaging quality.

[0164] Figure 4c A schematic structural diagram of the optical system of the fourth embodiment at the mid-focus end is shown. Figure 4dThe longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fourth embodiment at the mid-focus end are shown. Figure 4d It can be seen that the optical system provided in the fourth embodiment can achieve good imaging quality.

[0165] Figure 4e A schematic structural diagram of the optical system of the fourth embodiment at the telephoto end is shown. Figure 4f The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fourth embodiment at the telephoto end are shown. Figure 4f It can be seen that the optical system provided in the fourth embodiment can achieve good imaging quality.

[0166] The fifth embodiment,

[0167] Please refer to Figure 5a-5f The optical system of this embodiment includes, in order from the object side to the image side along the optical axis:

[0168] The first lens L1 has positive refractive power. The object-side surface S1 of the first lens L1 is convex at the near optical axis, and the image-side surface S2 is concave at the near optical axis. The object-side surface S1 of the first lens L1 is convex at the circumference, and the image-side surface S2 is concave at the circumference.

[0169] The second lens L2 has negative refractive power. The object-side surface S3 of the second lens L2 is convex at the near optical axis, and the image-side surface S4 is concave at the near optical axis. The object-side surface S3 of the second lens L2 is convex at the circumference, and the image-side surface S4 is concave at the circumference.

[0170] The third lens L3 has negative refractive power. The object-side surface S5 of the third lens L3 is convex at the near optical axis, and the image-side surface S6 is concave at the near optical axis. The object-side surface S5 of the third lens L3 is concave at the circumference, and the image-side surface S6 is convex at the circumference.

[0171] The fourth lens L4 has positive refractive power. The object-side surface S7 of the fourth lens L4 is convex at the near optical axis, and the image-side surface S8 is convex at the near optical axis. The object-side surface S7 of the fourth lens L4 is concave at the circumference, and the image-side surface S8 is convex at the circumference.

[0172] The fifth lens L5 has positive refractive power. The object-side surface S9 of the fifth lens L5 is convex at the near optical axis, and the image-side surface S10 is convex at the near optical axis. The object-side surface S9 of the fifth lens L5 is convex at the circumference, and the image-side surface S10 is convex at the circumference.

[0173] The sixth lens L6 has positive refractive power. The object-side surface S11 of the sixth lens is convex at the near optical axis, and the image-side surface S12 is convex at the near optical axis. The object-side surface S11 of the sixth lens L6 is convex at the circumference, and the image-side surface S12 is convex at the circumference.

[0174] The seventh lens L7 has negative refractive power. The object-side surface S13 of the seventh lens L7 is convex at the near optical axis, and the image-side surface S14 is concave at the near optical axis. The object-side surface S13 of the seventh lens L7 is concave at the circumference, and the image-side surface S14 is concave at the circumference.

[0175] The eighth lens L8 has positive refractive power. The object-side surface S15 of the eighth lens L8 is concave at the near optical axis, and the image-side surface S16 is convex at the near optical axis. The object-side surface S15 of the eighth lens L8 is concave at the circumference, and the image-side surface S16 is convex at the circumference.

[0176] The other structures of the fifth embodiment are the same as those of the first embodiment, and can be referred to herein.

[0177] Table 5a(1)-Table 5a(2) shows the characteristics of the optical system of this embodiment, and the units of Y radius, thickness and focal length are all millimeters (mm). The reference wavelength of the focal length is 555nm, and the reference wavelength of the refractive index and Abbe number is 587.56nm.

[0178] Table 5a(1)

[0179]

[0180] Table 5a(2)

[0181] Variable distance D1 D2 D3 f(mm) FNO FOV(°) Short focus position 0.7000 9.0700 3.7000 12.5 2.73 18.4 Mid-focus position 3.7649 4.1379 5.5615 17.3 3.21 13.1 Telephoto position 4.9601 1.1101 7.4040 21.7 3.93 10.4

[0182] The meanings of the parameters in Table 5a(1)-Table 5a(2) are the same as those in the first embodiment.

[0183] Table 5b gives the coefficients of the higher-order terms that can be used for each aspherical mirror surface in the fifth embodiment, wherein each aspherical surface shape can be defined by the formula given in the first embodiment.

[0184] Table 5b

[0185]

[0186] Figure 5a A schematic structural diagram of the optical system of the fifth embodiment at the short focal end is shown. Figure 5b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fifth embodiment at the short focal end are shown. Figure 5b It can be seen that the optical system provided in the fifth embodiment can achieve good imaging quality.

[0187] Figure 5c A schematic structural diagram of the optical system of the fifth embodiment at the mid-focus end is shown. Figure 5d The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fifth embodiment at the mid-focus end are shown. Figure 5d It can be seen that the optical system provided in the fifth embodiment can achieve good imaging quality.

[0188] Figure 5e A schematic structural diagram of the optical system of the fifth embodiment at the telephoto end is shown. Figure 5f The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fifth embodiment at the telephoto end are shown. Figure 5f It can be seen that the optical system provided in the fifth embodiment can achieve good imaging quality.

[0189] Table 6 shows the values ​​of fg2 / AT24, fc / fd, TTL / (D1+D2+D3), (g1+g2+g3) / fd, FNOc / FNOd, fg1 / fc, fg3 / |R15-R16|, f3 / fg2, sdmax / sdmin, g2 / ∑etg2, BFc / ImgH, and sag82 / sag81 of the optical systems of the first to fifth embodiments.

[0190] Table 6

[0191]

[0192]

[0193] It can be seen from Table 6 that each embodiment satisfies the following conditional formula: <fg2 / AT24<-10、fc / fd> 1.3, TTL / (D1+D2+D3)<2.6, (g1+g2+g3) / fd<0.9, FNOc / FNOd<1.6, 1 <fg1 / fc<8、0.8<fg3 / |R15-R16|<1.5、1<f3 / fg2<5、sdmax / sdmin<1.55、1.2<g2 / ∑etg2<1.8、BFc / ImgH<3.5、2.5<sag82 / sag81<3.5。

[0194] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, all possible combinations of the technical features in the above embodiments are not 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.

[0195] The above embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present invention. It should be pointed out that, for those of ordinary skill in the art, several modifications and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the present invention shall be subject to the attached claims.

Claims

1. An optical system, characterized in that: There are a total of eight lenses with refractive power, which successively include, from the object side to the image side along the optical axis direction: The first lens group, having positive refractive power, and the first lens group includes a first lens; The second lens group, having negative refractive power, and the second lens group includes a second lens, a third lens, and a fourth lens. The second lens has negative refractive power, the third lens has negative refractive power, and the fourth lens has positive refractive power; The third lens group, having positive refractive power, and the third lens group includes a fifth lens, a sixth lens, a seventh lens, and an eighth lens. The fifth lens has positive refractive power, the sixth lens has positive refractive power, the seventh lens has negative refractive power, and the eighth lens has positive refractive power; A filter, disposed between the eighth lens and the imaging surface; The distances between the first lens group, the second lens group, and the third lens group are adjustable so that the optical system is in the telephoto end, the mid - focal end, and the wide - angle end, and the focal lengths of the optical system in the telephoto end, the mid - focal end, and the wide - angle end are different; The optical system satisfies the conditional formula: - 70 < fg2 / AT24 < - 10, TTL / (D1 + D2 + D3) < 2.6, where fg2 is the focal length of the second lens group, AT24 is the sum of the air intervals on the optical axis between adjacent lenses in the second lens group, TTL is the distance on the optical axis from the object side surface of the first lens to the imaging surface of the optical system, D1 is the distance on the optical axis from the object side surface of the first lens to the image side surface of the second lens, D2 is the distance on the optical axis from the image side surface of the fourth lens to the object side surface of the fifth lens, and D3 is the distance on the optical axis from the image side surface of the filter to the imaging surface.

2. The optical system according to claim 1, characterized in that The optical system satisfies the conditional formula: fc / fd > 1.3, where fc is the focal length of the optical system in the telephoto end and fd is the focal length of the optical system in the wide - angle end.

3. The optical system according to claim 1, characterized in that The optical system satisfies the conditional formula: (g1 + g2 + g3) / fd < 0.9, where g1 is the distance on the optical axis from the object side surface of the first lens to the image side surface of the first lens, g2 is the distance on the optical axis from the object side surface of the second lens to the image side surface of the fourth lens, g3 is the distance on the optical axis from the object side surface of the fifth lens to the image side surface of the seventh lens, and fd is the focal length of the optical system in the wide - angle end.

4. The optical system according to claim 1, characterized in that The optical system satisfies the conditional formula: FNOc / FNOd < 1.6, where FNOc is the f - number of the optical system in the telephoto end and FNOd is the f - number of the optical system in the wide - angle end.

5. The optical system according to claim 1, characterized in that The optical system satisfies the conditional formula: 1 < fg1 / fc < 8, where fg1 is the focal length of the first lens group and fc is the focal length of the optical system in the telephoto end.

6. The optical system according to claim 1, characterized in that The optical system satisfies the conditional formula: 0.8 < fg3 / |R15 - R16| < 1.5, where fg3 is the focal length of the third lens group, R15 is the curvature radius at the optical axis of the object side surface of the eighth lens, and R16 is the curvature radius at the optical axis of the image side surface of the eighth lens.

7. The optical system according to claim 1, characterized in that The optical system satisfies the conditional formula: 1 < f3 / fg2 < 5, where f3 is the focal length of the third lens and fg2 is the focal length of the second lens group.

8. The optical system according to claim 1, characterized in that The optical system satisfies the conditional formula: sdmax / sdmin < 1.55, where sdmax is the maximum value among the maximum effective radii of the object side and the image side of the first lens to the eighth lens, and sdmin is the minimum value among the maximum effective radii of the object side and the image side of the first lens to the eighth lens.

9. The optical system according to claim 1, characterized in that The optical system satisfies the conditional formula: 1.2 < g2 / ∑etg2 < 1.8, where g2 is the distance on the optical axis from the object side of the second lens to the image side of the fourth lens, and ∑etg2 is the sum of the edge thicknesses of the lenses in the second lens group.

10. The optical system according to claim 1, characterized in that The optical system satisfies the conditional formula: BFc / ImgH < 3.5, where BFc is the minimum axial distance from the image side of the eighth lens to the imaging surface when the optical system is at the telephoto end, and ImgH is half of the diagonal length of the effective pixel area of the imaging surface.

11. The optical system according to claim 1, characterized in that The optical system satisfies the conditional formula: 2.5 < sag82 / sag81 < 3.5, where sag81 is the sagitta at the maximum effective radius of the object side of the eighth lens, and sag82 is the sagitta at the maximum effective radius of the image side of the eighth lens.

12. A camera module, characterized in that: It includes a lens barrel, an electronic photosensitive element, and the optical system according to any one of claims 1 to 11. The first lens to the eighth lens of the optical system are installed in the lens barrel, and the electronic photosensitive element is placed on the image side of the optical system.

13. An electronic device, characterized in that: It includes a housing and the imaging module according to claim 12. The imaging module is provided in the housing.

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