Optical systems, lens modules and electronic devices

Abstract

The present invention provides an optical system, a lens module and an electronic device. The optical system includes, in order from the object side to the image side along the optical axis: a first lens having positive refractive power, the object side surface of the first lens being convex, and the image side surface of the near optical axis region thereof being concave; a second lens; a third lens having positive refractive power, the object side surface of the third lens being convex; a fourth lens; a fifth lens, the object side surface and the image side surface of the near circumferential region of the fifth lens being convex; a sixth lens; a seventh lens having negative refractive power, the object side surface of the near optical axis region of the seventh lens being convex, and the image side surface of the near optical axis region being concave; and at least one of the object side surface and the image side surface of the fifth lens and the seventh lens is provided with at least one inflection point. Through the above-mentioned arrangement, the distortion, astigmatism and spherical aberration generated by the front lens group are balanced, which is conducive to improving the resolution; at the same time, the provision of multiple inflection points facilitates reducing the curvature of the lens, thereby reducing the axial thickness of the lens, which helps to reduce the size.

Description

Technical Field

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

[0002] With the advancement of science and technology and the widespread adoption of smartphones and other smart electronic devices, devices with diverse camera functions are gaining widespread popularity. The optical system is a core component of these devices. The resolution of the optical system directly affects the device's image quality, and the size of the optical system determines the device's size.

[0003] In previous seven-element optical systems, the large number of lenses made it difficult to maintain an appropriate axial thickness. Therefore, reducing the axial thickness of the optical system while maintaining high resolution has become a key research priority. Summary of the Invention

[0004] The object of the present invention is to provide an optical system that can solve the above-mentioned problems.

[0005] To achieve the purpose of the present invention, the present invention provides the following technical solutions:

[0006] In a first aspect, the present invention provides an optical system, which includes, in order from the object side to the image side along the optical axis direction: a first lens having positive refractive power, wherein the object side surface of the first lens in the near optical axis region and the near circumferential region is convex, and the image side surface of the first lens in the near optical axis region is concave; a second lens having refractive power; a third lens having positive refractive power, wherein the object side surface of the third lens in the near optical axis region and the near circumferential region is convex; a fourth lens having refractive power; a fifth lens having refractive power, wherein the object side surface and the image side surface of the near circumferential region of the fifth lens are convex, both the object side surface and the image side surface of the fifth lens are aspherical, and at least one of the object side surface and the image side surface of the fifth lens is provided with at least one inflection point; a sixth lens having refractive power; a seventh lens having negative refractive power, wherein the object side surface of the seventh lens in the near optical axis region is convex, and the image side surface of the seventh lens in the near optical axis region is concave, both the object side surface and the image side surface of the fifth lens are aspherical, and at least one of the object side surface and the image side surface of the fifth lens is provided with at least one inflection point. The fifth and seventh lenses are equipped with multiple inflection points, which help correct the distortion and field curvature produced by the front lens group, ensuring a more uniform distribution of refractive power near the imaging plane and reducing the sensitivity of the optical system. By rationally configuring the refractive power and surface shape of each lens from the first to the seventh lens, the distortion, astigmatism, and spherical aberration produced by the front lens group are balanced, particularly for distortion at large fields of view. This ensures a good balance between aberration and resolving power across the field of view, which helps improve the resolving power of the optical system. Furthermore, the multiple inflection points minimize the curvature of the lenses, thereby reducing their axial thickness and contributing to a smaller optical system.

[0007] In one embodiment, the second lens has negative refractive power, the object side surface of the second lens near the optical axis region is convex, and the image side surface of the second lens near the optical axis region and near the circumference region is concave; the object side surface of the fourth lens near the optical axis region is concave, and the image side surface of the fourth lens near the optical axis region is convex; the object side surface of the sixth lens near the circumference region is concave, and the image side surface of the sixth lens near the circumference region is convex; both the object side and image side surfaces of the sixth lens are aspherical, and at least one of the object side and image side surfaces of the sixth lens is provided with at least one inflection point. By optimizing the refractive power and surface shape of the second, fourth, and sixth lenses, it is easier to balance the distortion, astigmatism, and spherical aberration generated by the front lens group, thereby improving the degree of compensation for distortion of the optical system for a large field of view and further improving the resolution of the optical system. At the same time, the addition of inflection points further reduces the curvature of the lens, thereby reducing the axial thickness of the lens and further reducing the size of the optical system.

[0008] In one embodiment, the first lens is a glass lens, and both the object side and the image side of the first lens are aspherical surfaces, and the first lens satisfies the condition: n12>1.7; wherein n12 is the refractive index of the first lens for light with a wavelength of 546nm. By setting the first lens to be made of glass, the first lens has a higher refractive index, which makes it easier to distribute the refractive power of the first lens, reduces the thickness of the first lens, and improves the overall compactness. Due to the characteristics of glass, the assembled optical lens system has a small deformation in high and low temperature environments and more stable imaging performance. Reasonable setting of the value of n12 makes the first lens have a high refractive power, which can better balance spherical aberration and chromatic aberration, which is beneficial to the aberration balance of the rear lens. At the same time, it can quickly reduce the angle of incident light with a large field of view and reduce the tolerance sensitivity of the system.

[0009] In one embodiment, the optical system satisfies the following condition: 1.35 ≤ f / EPD ≤ 2, where f is the effective focal length of the optical system and EPD is the entrance pupil diameter. By properly setting the f / EPD value, the optical system receives sufficient light, preventing vignetting of the electronic photosensitive element and further improving photography in dark environments. Furthermore, increasing the aperture number reduces the size of the Airy disk, further improving the resolution limit, which is inversely proportional to the size of the Airy disk. By properly configuring the lens resolution, high-pixel design requirements can be met.

[0010] In one embodiment, the optical system satisfies the conditional formula: 0.6<TTL / (ImgH*2)<0.8; 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, and ImgH is half the diagonal length of the effective photosensitive area of ​​the optical system. It can be understood that ImgH determines the size of the electronic photosensitive element. The larger the ImgH, the larger the maximum supported electronic photosensitive element size. ImgH ≥ 3.4mm can meet the high pixel and high image quality requirements of most mobile phone lenses. The smaller the TTL, the better the overall length compression effect of the optical system, and the more compact the lens structure. By reasonably setting the value of TTL / (ImgH*2), the optical system can be miniaturized and lightweight while meeting high pixel and high imaging quality.

[0011] In one embodiment, the optical system satisfies the conditional equation: 1.6 < (|SAG71| + CT7 + SAG72) / CT7 < 3.3; wherein SAG71 is the maximum sag of the object-side surface of the seventh lens element, CT7 is the thickness of the seventh lens element along the optical axis, and SAG72 is the maximum sag of the image-side surface of the seventh lens element. By properly setting the value of (|SAG71| + CT7 + SAG72) / CT7, the refractive power and thickness of the lens element in the direction perpendicular to the optical axis can be properly controlled, preventing the lens element from being too thin or too thick, reducing the difficulty of lens molding, and facilitating the manufacture of the optical system.

[0012] In one embodiment, the optical system satisfies the conditional equation: 0.2 < n12 / R12 ≤ 0.4; where n12 is the refractive index of the first lens for light with a wavelength of 546 nm, and R12 is the radius of curvature of the image-side surface of the first lens at the optical axis. By properly setting the value of n12 / R12, a higher refractive index facilitates a smaller physical size of the first lens, facilitating the design of a thin and lightweight lens, while also avoiding excessive concentration of refractive power that could increase aberrations.

[0013] In one embodiment, the optical system satisfies the conditional formula: (ET1+ET2+ET3) / (CT1+CT2+CT3)<1; wherein ET1 is the thickness of the edge of the optically effective area of ​​the first lens, ET2 is the thickness of the edge of the optically effective area of ​​the second lens, ET3 is the thickness of the edge of the optically effective area of ​​the third lens, CT1 is the thickness of the first lens on the optical axis, CT2 is the thickness of the second lens on the optical axis, and CT3 is the thickness of the third lens on the optical axis. By reasonably setting the value of (ET1+ET2+ET3) / (CT1+CT2+CT3), the sizes and refractive powers of the first, second, and third lenses are optimized, and excessive spherical aberration generated by the front lens group can be avoided, thereby improving the overall resolution of the optical lens and reducing the sensitivity of the lens group.

[0014] In one embodiment, the optical system satisfies the condition: 1.75 ≤ |f45 / f3| < 41; where f45 is the combined effective focal length of the fourth and fifth lenses, and f3 is the effective focal length of the third lens. It is understood that the object side of the fourth lens is concave, providing good refractive power distribution perpendicular to the optical axis. By properly setting the value of |f45 / f3|, field curvature and distortion caused by excessive light deflection angles can be reduced, thereby improving image quality and reducing the assembly sensitivity of the optical system.

[0015] In one embodiment, the optical system satisfies the conditional equation: |f6 / R61| < 22, where f6 is the effective focal length of the sixth lens element, and R61 is the radius of curvature of the object-side surface of the sixth lens element at the optical axis. By properly setting the value of |f6 / R61|, the sixth lens element can be kept thin and lightweight, helping to reduce the thickness of the optical system and improve image quality.

[0016] In one embodiment, the optical system satisfies the following condition: 70° ≤ FOV ≤ 85°; where FOV is the maximum field of view (FOV) of the optical system in the diagonal direction. This configuration provides a maximum shooting range exceeding 70° at a low aperture number, fully utilizing the advantages of a low aperture number, increasing the amount of light entering the electronic photosensitive element per unit area and improving the ability to capture low-frequency details of objects. The combination of a low aperture number and a wide FOV reduces the depth of field of the captured object, further highlighting the subject, and thus improving image quality.

[0017] In one embodiment, the optical system satisfies the following condition: 0.8 < f13 / f < 1.1; where f13 is the combined effective focal length of the first, second, and third lenses, and f is the effective focal length of the optical system. Properly setting the value of f13 / f optimizes the refractive power of the first, second, and third lenses, reducing the size of the lens head, lowering the deflection angle of incident light within a large field of view, and lowering the sensitivity of the system.

[0018] In a second aspect, the present invention further provides a lens module comprising a lens barrel, an electronic photosensitive element, and the optical system according to any one of the embodiments of the first aspect, wherein the first through seventh lenses of the optical system are mounted within the lens barrel, and the electronic photosensitive element is disposed on the image side of the optical system. By mounting the first through seventh lenses of the optical system within the lens module, aberrations and resolution across various fields of view are well balanced, thereby improving the resolution of the lens module and contributing to a reduction in size.

[0019] In a third aspect, the present invention further provides an electronic device comprising a housing and the lens module according to the second aspect, the lens module being disposed within the housing. By incorporating the lens module according to the second aspect into the electronic device, aberrations and resolution across various fields of view are well balanced, thereby improving the resolution of the electronic device and contributing to its size reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1a is a schematic structural diagram of the optical system of the first embodiment;

[0022] Figure 1b 1 are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the first embodiment;

[0023] Figure 2a is a schematic structural diagram of the optical system of the second embodiment;

[0024] Figure 2b 1 and 2 are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the second embodiment;

[0025] Figure 3a is a schematic structural diagram of an optical system according to a third embodiment;

[0026] Figure 3b 1 and 2 are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the third embodiment;

[0027] Figure 4a is a schematic structural diagram of an optical system according to a fourth embodiment;

[0028] Figure 4b 1 and 2 are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the fourth embodiment;

[0029] Figure 5a is a schematic structural diagram of an optical system according to a fifth embodiment;

[0030] Figure 5b 1 and 2 are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the fifth embodiment;

[0031] Figure 6a is a schematic structural diagram of the optical system of the sixth embodiment;

[0032] Figure 6b 1 and 2 are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the sixth embodiment.

[0033] Figure 7a is a schematic structural diagram of the optical system of the seventh embodiment;

[0034] Figure 7b 1 and 2 are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the seventh embodiment. DETAILED DESCRIPTION

[0035] The following will be combined with the accompanying 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 embodiments described 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 making creative efforts are within the scope of protection of the present invention.

[0036] The present invention also provides a lens module, which includes a lens barrel, an electronic photosensitive element and an optical system provided by an embodiment of the present invention. The first lens to the seventh 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 that passes through the first lens to the seventh lens and is incident on the electronic photosensitive element 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 lens module can be an independent lens of a digital camera, or it can be an imaging module integrated in an electronic device such as a smartphone. By installing the first lens to the seventh lens of the optical system provided by an embodiment of the present invention in the lens module, the aberration and resolution of each field of view are well balanced, which is conducive to improving the resolution of the lens module and helping to reduce the size of the lens module.

[0037] The present invention also provides an electronic device comprising a housing and a lens module according to an embodiment of the present invention, the lens module being disposed within the housing. The electronic device may be a smartphone, a personal digital assistant (PDA), a tablet computer, a smartwatch, an unmanned aerial vehicle (UAV), an e-book reader, a driving recorder, a wearable device, or the like. By incorporating the lens module according to the present invention into the electronic device, a good balance between aberration and resolution in each field of view is achieved, thereby improving the resolution of the electronic device and contributing to its size reduction.

[0038] The present invention provides an optical system, which includes, along the optical axis from the object side to the image side, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens. Among the first to seventh lenses, any two adjacent lenses may have an air gap between them.

[0039] Specifically, the specific shape and structure of the seven lenses are as follows:

[0040] The first lens has positive refractive power, the object-side surface of the first lens near the optical axis and near the circumference area is convex, and the image-side surface of the first lens near the optical axis area is concave;

[0041] The second lens has refractive power;

[0042] The third lens has positive refractive power, and the object side surface of the third lens near the optical axis and near the circumference area is convex;

[0043] The fourth lens has refractive power;

[0044] a fifth lens element having refractive power, wherein the object-side surface and the image-side surface of the fifth lens element in a near-circumferential region are convex, both the object-side surface and the image-side surface of the fifth lens element are aspherical, and at least one of the object-side surface and the image-side surface of the fifth lens element is provided with at least one inflection point;

[0045] a sixth lens having refractive power;

[0046] The seventh lens element has negative refractive power. The object-side surface of the seventh lens element in the near optical axis region is convex, and the image-side surface of the seventh lens element in the near optical axis region is concave. Both the object-side surface and the image-side surface of the fifth lens element are aspherical surfaces, and at least one of the object-side surface and the image-side surface of the fifth lens element is provided with at least one inflection point.

[0047] Specifically, the optical system further includes an aperture, which can be set at any position between the first lens to the seventh lens, such as on the first lens.

[0048] It is understood that the multiple inflection points of the fifth and seventh lenses help correct the distortion and field curvature produced by the front lens group, ensuring a more uniform distribution of refractive power near the imaging plane and reducing the sensitivity of the optical system. By rationally configuring the refractive power and surface shape of each lens from the first to the seventh lens, the distortion, astigmatism, and spherical aberration produced by the front lens group are balanced, particularly for distortion at large fields of view. This achieves a good balance between aberration and resolving power across the field of view, which helps improve the resolving power of the optical system. Furthermore, the multiple inflection points minimize the curvature of the lenses, thereby reducing their axial thickness and contributing to a smaller optical system.

[0049] In one embodiment, the second lens element has negative refractive power, the object-side surface of the second lens near the optical axis region is convex, and the image-side surface of the second lens near the optical axis region and near the periphery region is concave; the object-side surface of the fourth lens near the optical axis region is concave, and the image-side surface of the fourth lens near the optical axis region is convex; the object-side surface of the sixth lens near the periphery region is concave, and the image-side surface of the sixth lens near the periphery region is convex; both the object-side and image-side surfaces of the sixth lens are aspherical, and at least one of the object-side and image-side surfaces of the sixth lens is provided with at least one inflection point. Specifically, multiple inflection points may be provided on the first lens element, the second lens element, the third lens element, and the fourth lens element. By optimizing the refractive power and surface shape of the second, fourth, and sixth lenses, the distortion, astigmatism, and spherical aberration generated by the front lens group are balanced, the degree of distortion compensation of the optical system for a wide field of view is improved, and the resolution of the optical system is further improved. At the same time, the addition of inflection points further reduces the curvature of the lenses, thereby reducing the axial thickness of the lenses and further reducing the size of the optical system.

[0050] In one embodiment, the first lens is a glass lens, and both the object side and the image side of the first lens are aspherical surfaces, and the first lens satisfies the condition: n12>1.7; wherein n12 is the refractive index of the first lens for light with a wavelength of 546nm. Specifically, it is preferred that the second to seventh lenses are all made of plastic material, which can be resins such as polymethyl methacrylate, propylene glycol carbonate and propylene glycol carbonate. The value of n12 can be 1.7, 1.9, 2.5, 3.5 and 5, etc. It can be understood that the 1G6P aspherical optical system formed by the first lens made of glass and the second to seventh lenses made of plastic can take into account both light and thin characteristics and high resolution, and the application scenarios are more diversified. Glass has a higher refractive index than plastic shells. By setting the first lens material to be glass, the first lens has a higher refractive index, making the refractive power of the first lens easier to distribute, reducing the thickness of the first lens, and improving the overall compactness. Due to the characteristics of glass, the assembled optical lens system has small deformation in high and low temperature environments and more stable imaging performance. Reasonable setting of the value of n12 makes the first lens have high refractive power, which can better balance spherical aberration and chromatic aberration, which is beneficial to the aberration balance of the rear lens. At the same time, it can quickly reduce the angle of incident light at a large field of view, reducing the tolerance sensitivity of the system.

[0051] In one embodiment, the optical system satisfies the conditional formula: 1.35 ≤ f / EPD ≤ 2, where f is the effective focal length of the optical system and EPD is the entrance pupil diameter of the optical system. Specifically, the value of f / EPD can be 1.35, 1.4, 1.45, 1.5, 1.55, 1.6, 1.7, 1.8, 1.9, and 2.0, among others. By properly setting the f / EPD value, the optical system receives sufficient light, preventing vignetting of the electronic photosensitive element and further improving photography in dark environments. Furthermore, increasing the aperture number reduces the size of the Airy disk, further improving the resolution limit, which is inversely proportional to the size of the Airy disk. By properly configuring the lens resolution, high-pixel design requirements can be met.

[0052] In one embodiment, the optical system satisfies the conditional formula: 0.6<TTL / (ImgH*2)<0.8; wherein TTL is the distance from the object side of the first lens to the imaging plane of the optical system on the optical axis, and ImgH is half the diagonal length of the effective photosensitive area of ​​the optical system. Specifically, the value of TTL / (ImgH*2) can be 0.6, 0.65, 0.68, 0.7, 0.72, 0.75 and 0.8, etc. It can be understood that ImgH determines the size of the electronic photosensitive element. The larger the ImgH, the larger the maximum supported electronic photosensitive element size. ImgH ≥ 3.4mm can meet the high pixel and high image quality requirements of most mobile phone lenses; the smaller the TTL, the better the overall length compression effect of the optical system, and the more compact the lens structure. By reasonably setting the value of TTL / (ImgH*2), the optical system can be miniaturized and lightweight while meeting high pixel and high imaging quality.

[0053] In one embodiment, the optical system satisfies the conditional formula: 1.6<(|SAG71|+CT7+SAG72) / CT7<3.3; wherein SAG71 is the maximum sagittal height of the object side surface of the seventh lens, CT7 is the thickness of the seventh lens on the optical axis, and SAG72 is the maximum sagittal height of the image side surface of the seventh lens. Specifically, the value of (|SAG71|+CT7+SAG72) / CT7 can be 1.6, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3 and 3.3, etc. By reasonably setting the value of (|SAG71|+CT7+SAG72) / CT7, the refractive power and thickness of the lens in the direction perpendicular to the optical axis can be reasonably controlled, avoiding the lens being too thin or too thick, reducing the difficulty of lens molding, and facilitating the manufacture of the optical system.

[0054] In one embodiment, the optical system satisfies the conditional equation: 0.2 < n12 / R12 ≤ 0.4; where n12 is the refractive index of the first lens element for light with a wavelength of 546 nm, and R12 is the radius of curvature of the image-side surface of the first lens element at the optical axis. Specifically, n12 / R12 can be 0.2, 0.25, 0.3, 0.35, or 0.4. By properly setting the n12 / R12 value, a higher refractive index facilitates a reduced physical size of the first lens element, facilitating the design of a thin and lightweight lens. This also avoids excessive concentration of refractive power, which can increase aberrations.

[0055] In one embodiment, the optical system satisfies the conditional formula: (ET1+ET2+ET3) / (CT1+CT2+CT3)<1; wherein ET1 is the thickness of the edge of the optically effective area of ​​the first lens, ET2 is the thickness of the edge of the optically effective area of ​​the second lens, ET3 is the thickness of the edge of the optically effective area of ​​the third lens, CT1 is the thickness of the first lens on the optical axis, CT2 is the thickness of the second lens on the optical axis, and CT3 is the thickness of the third lens on the optical axis. Specifically, the value of (ET1+ET2+ET3) / (CT1+CT2+CT3) can be 0.3, 0.5, 0.6, 0.65, 0.7, 0.75, 0.8, 0.9 and 1, etc. By reasonably setting the value of (ET1+ET2+ET3) / (CT1+CT2+CT3), optimizing the size and refractive power of the first lens, the second lens and the third lens, it is possible to avoid excessive spherical aberration generated by the front lens group, thereby improving the overall resolution of the optical lens and reducing the sensitivity of the lens group.

[0056] In one embodiment, the optical system satisfies the conditional formula: 1.75 ≤ |f45 / f3| < 41; wherein f45 is the combined effective focal length of the fourth and fifth lenses, and f3 is the effective focal length of the third lens. Specifically, the value of |f45 / f3| can be 1.75, 16, 23, 30, 37, 40, and 41, among others. It is understood that the object side of the fourth lens is concave, providing good refractive power distribution perpendicular to the optical axis. By properly setting the value of |f45 / f3|, it is beneficial to reduce field curvature and distortion caused by excessive light deflection angles, thereby improving image quality and reducing the assembly sensitivity of the optical system.

[0057] In one embodiment, the optical system satisfies the conditional equation: |f6 / R61| < 22, where f6 is the effective focal length of the sixth lens element, and R61 is the radius of curvature of the object-side surface of the sixth lens element at the optical axis. Specifically, the value of |f6 / R61| can be 0.1, 0.5, 1, 5, 10, 15, or 22. By properly setting the value of |f6 / R61|, the thinness of the sixth lens element can be maintained, helping to reduce the thickness of the optical system and improve image quality.

[0058] In one embodiment, the optical system satisfies the conditional formula: 70°≤FOV≤85°; wherein FOV is the maximum field of view angle of the optical system in the diagonal direction. Specifically, the FOV value can be 70°, 73°, 75°, 78°, 80°, 83°, and 85°, etc. Through the above setting, a maximum shooting range of more than 70° is provided at a low aperture number, making full use of the advantage of a low aperture number, increasing the amount of light entering per unit area of ​​the electronic photosensitive element, and improving the ability to capture low-frequency details of the object; a low aperture number combined with a large field of view can reduce the depth of field of the photographed object, more prominently highlight the subject, and thus improve image quality.

[0059] In one embodiment, the optical system satisfies the following condition: 0.8 < f13 / f < 1.1; where f13 is the combined effective focal length of the first, second, and third lenses, and f is the effective focal length of the optical system. Specifically, the values ​​of f13 / f can be 0.8, 0.85, 0.9, 0.95, 1, 1.05, and 1.1, among others. Properly setting the value of f13 / f optimizes the refractive power of the first, second, and third lenses, reduces the size of the lens head, decreases the deflection angle of incident light within a large field of view, and reduces system sensitivity.

[0060] First embodiment

[0061] Please refer to Figure 1a and Figure 1b The optical system of this embodiment includes, in order from the object side to the image side along the optical axis:

[0062] The first lens element L1 has positive refractive power. The object-side surface S1 of the first lens element L1 near the optical axis and near the periphery is convex. The image-side surface S2 of the first lens element L1 near the optical axis is concave, and the image-side surface S2 near the periphery is convex.

[0063] The second lens element L2 has negative refractive power. The object-side surface S3 of the second lens element L2 near the optical axis and near the periphery is convex, and the image-side surface S4 of the second lens element L2 near the optical axis and near the periphery is concave.

[0064] The third lens element L3 has positive refractive power. The object-side surface S5 of the third lens element L3 near the optical axis is convex, and the object-side surface S5 near the periphery is concave. The image-side surface S6 of the third lens element L3 near the optical axis and near the periphery is concave.

[0065] The fourth lens element L4 has positive refractive power. The object-side surface S7 of the fourth lens element L4 near the optical axis and near the circumference is concave, and the image-side surface S8 of the fourth lens element L4 near the optical axis and near the circumference is convex.

[0066] The fifth lens element L5 has positive refractive power. The object-side surface S9 of the fifth lens element L5 in the near-optical-axis area is convex, and the object-side surface S9 in the near-circumferential area is concave. The image-side surface S10 of the fifth lens element L5 in the near-optical-axis area is concave, and the image-side surface S10 in the near-circumferential area is convex.

[0067] The sixth lens element L6 has negative refractive power. The object-side surface S11 of the sixth lens element L6 in the near optical axis region and near the circumference region is concave; the image-side surface S12 of the sixth lens element L6 in the near optical axis region and near the circumference region is convex.

[0068] The seventh lens element L7 has negative refractive power. The object-side surface S13 of the seventh lens element L7 in the near optical axis region and near the peripheral region is convex. The image-side surface S14 of the seventh lens element L7 in the near optical axis region is concave, and the image-side surface S14 in the near peripheral region is convex.

[0069] The first lens L1 is made of glass, and the second lens L2 to the seventh lens L7 are all made of plastic.

[0070] In addition, the optical system also includes an aperture STO, an infrared cutoff filter L8 and an imaging surface S17. The aperture STO is arranged on the side of the first lens L1 away from the second lens L2, and is used to control the amount of light entering. In other embodiments, the aperture STO can also be arranged between two adjacent lenses, or on other lenses. The infrared cutoff filter L8 is arranged on the image side of the seventh lens L7, which includes an object side surface S15 and an image side surface S16. The infrared cutoff filter L8 is used to filter out infrared light so that the light incident on the imaging surface S17 is visible light, and the wavelength of visible light is 380nm-780nm. The material of the infrared cutoff filter L8 is glass, and a film can be coated on the glass. The imaging surface S17 is the effective pixel area of ​​the electronic photosensitive element.

[0071] Table 1a shows a table of characteristics of the optical system of this embodiment, wherein the data are obtained using light with a wavelength of 546 nm, and the units of Y radius, thickness and focal length are all millimeters (mm).

[0072] Table 1a

[0073]

[0074]

[0075] Wherein, f is the effective focal length of the optical system, FNO is the aperture number of the optical system, FOV is the maximum field angle of the optical system in the diagonal direction, 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.

[0076] In this embodiment, the object-side surface and the image-side surface of any lens from the first lens L1 to the seventh lens L7 are both aspherical surfaces. The surface shape x of each aspherical lens can be defined by, but is not limited to, the following aspherical surface formula:

[0077]

[0078] Where x is the maximum sag height of the aspheric surface at a height h along the optical axis, from the vertex of the aspheric surface; c is the paraxial curvature of the aspheric surface, c = 1 / R (i.e., the paraxial curvature c is the reciprocal of the Y radius R in Table 1a above); k is the conic coefficient; Ai is the correction coefficient for the i-th order of the aspheric surface. Table 1b lists the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for each aspheric mirror surface S1-S10 in the first embodiment.

[0079] Table 1b

[0080]

[0081]

[0082] Figure 1b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the first embodiment are shown. The reference wavelength of the light of the astigmatism curve and distortion curve is 546nm, among which the longitudinal spherical aberration curve represents the deviation of the focal point of light of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the meridional image curvature and sagittal image curvature; the distortion curve represents the distortion 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.

[0083] Second embodiment

[0084] Please refer to Figure 2a and Figure 2b The optical system of this embodiment includes, in order from the object side to the image side along the optical axis:

[0085] The first lens element L1 has positive refractive power. The object-side surface S1 of the first lens element L1 near the optical axis and near the periphery is convex. The image-side surface S2 of the first lens element L1 near the optical axis is concave, and the image-side surface S2 near the periphery is convex.

[0086] The second lens element L2 has negative refractive power. The object-side surface S3 of the second lens element L2 near the optical axis and near the periphery is convex, and the image-side surface S4 of the second lens element L2 near the optical axis and near the periphery is concave.

[0087] The third lens L3 has positive refractive power. The object-side surface S5 of the third lens L3 near the optical axis and near the periphery is convex. The image-side surface S6 of the third lens L3 near the optical axis and near the periphery is convex.

[0088] The fourth lens element L4 has negative refractive power. The object-side surface S7 of the fourth lens element L4 near the optical axis and near the circumference is concave. The image-side surface S8 of the fourth lens element L4 near the optical axis is convex, and the image-side surface S8 near the circumference is concave.

[0089] The fifth lens element L5 has positive refractive power. The object-side surface S9 of the fifth lens element L5 in the near-optical-axis area is convex, and the object-side surface S9 in the near-circumferential area is concave. The image-side surface S10 of the fifth lens element L5 in the near-optical-axis area is concave, and the image-side surface S10 in the near-circumferential area is convex.

[0090] The sixth lens element L6 has positive refractive power. The object-side surface S11 of the sixth lens element L6 in the near-optical-axis region is convex, and the object-side surface S11 in the near-circumferential region is concave. The image-side surface S12 of the sixth lens element L6 in the near-optical-axis region and the near-circumferential region is convex.

[0091] The seventh lens element L7 has negative refractive power. The object-side surface S13 of the seventh lens element L7 in the near-optical-axis region is convex, and the object-side surface S13 in the near-circumferential region is concave. The image-side surface S14 of the seventh lens element L7 in the near-optical-axis region is concave, and the image-side surface S14 in the near-circumferential region is convex.

[0092] The other structures of the second embodiment are the same as those of the first embodiment, and can be used as a reference.

[0093] Table 2a shows a table of characteristics of the optical system of this embodiment, wherein the data are obtained using light with a wavelength of 546 nm, and the units of Y radius, thickness and focal length are all millimeters (mm).

[0094] Table 2a

[0095]

[0096] The meanings of the parameters in Table 2a are the same as those in the first embodiment.

[0097] Table 2b gives the high-order coefficients of each aspherical mirror surface that can be used in the second embodiment, wherein each aspherical surface shape can be defined by the formula given in the first embodiment.

[0098] Table 2b

[0099]

[0100]

[0101] Figure 2b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the second embodiment are shown. The reference wavelength of the light of the astigmatism curve and the distortion curve is 546nm. Figure 2b It can be seen that the optical system provided in the second embodiment can achieve good imaging quality.

[0102] Third embodiment

[0103] Please refer to Figure 3a and Figure 3b The optical system of this embodiment includes, in order from the object side to the image side along the optical axis:

[0104] The first lens element L1 has positive refractive power. The object-side surface S1 of the first lens element L1 near the optical axis and near the periphery is convex. The image-side surface S2 of the first lens element L1 near the optical axis is concave, and the image-side surface S2 near the periphery is convex.

[0105] The second lens element L2 has negative refractive power. The object-side surface S3 of the second lens element L2 near the optical axis and near the periphery is convex, and the image-side surface S4 of the second lens element L2 near the optical axis and near the periphery is concave.

[0106] The third lens element L3 has positive refractive power. The object-side surface S5 of the third lens element L3 near the optical axis is convex, and the object-side surface S5 near the periphery is concave. The image-side surface S6 of the third lens element L3 near the optical axis and near the periphery is convex.

[0107] The fourth lens element L4 has positive refractive power. The object-side surface S7 of the fourth lens element L4 near the optical axis and near the circumference is concave. The image-side surface S8 of the fourth lens element L4 near the optical axis is convex, and the image-side surface S8 near the circumference is concave.

[0108] The fifth lens element L5 has negative refractive power. The object-side surface S9 of the fifth lens element L5 in the near-optical-axis area is convex, and the object-side surface S9 in the near-circumferential area is concave. The image-side surface S10 of the fifth lens element L5 in the near-optical-axis area is concave, and the image-side surface S10 in the near-circumferential area is convex.

[0109] The sixth lens element L6 has positive refractive power. The object-side surface S11 of the sixth lens element L6 in the near optical axis region and near the circumference region is concave; the image-side surface S12 of the sixth lens element L6 in the near optical axis region and near the circumference region is convex.

[0110] The seventh lens element L7 has negative refractive power. The object-side surface S13 of the seventh lens element L7 in the near optical axis region and near the peripheral region is convex. The image-side surface S14 of the seventh lens element L7 in the near optical axis region is concave, and the image-side surface S14 in the near peripheral region is convex.

[0111] The other structures of the third embodiment are the same as those of the first embodiment, and can be used as a reference.

[0112] Table 3a shows a table of characteristics of the optical system of this embodiment, wherein the data are obtained using light with a wavelength of 546 nm, and the units of Y radius, thickness and focal length are all millimeters (mm).

[0113] Table 3a

[0114]

[0115] The meanings of the parameters in Table 3a are the same as those in the first embodiment.

[0116] Table 3b gives the high-order coefficients of each aspheric mirror surface that can be used in the third embodiment, wherein each aspheric surface shape can be defined by the formula given in the first embodiment.

[0117] Table 3b

[0118]

[0119]

[0120] Figure 3b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the third embodiment are shown. The reference wavelength of the light of the astigmatism curve and the distortion curve is 546nm. Figure 3b It can be seen that the optical system provided in the third embodiment can achieve good imaging quality.

[0121] Fourth embodiment

[0122] Please refer to Figure 4a and Figure 4b The optical system of this embodiment includes, in order from the object side to the image side along the optical axis:

[0123] The first lens element L1 has positive refractive power. The object-side surface S1 of the first lens element L1 near the optical axis and near the periphery is convex. The image-side surface S2 of the first lens element L1 near the optical axis is concave, and the image-side surface S2 near the periphery is convex.

[0124] The second lens element L2 has negative refractive power. The object-side surface S3 of the second lens element L2 near the optical axis is convex, the object-side surface S3 near the periphery is concave, and the image-side surface S4 of the second lens element L2 near the optical axis and near the periphery is concave.

[0125] The third lens element L3 has positive refractive power. The object-side surface S5 of the third lens element L3 near the optical axis is convex, and the object-side surface S5 near the periphery is concave. The image-side surface S6 of the third lens element L3 near the optical axis is concave, and the image-side surface S6 near the periphery is convex.

[0126] The fourth lens element L4 has positive refractive power. The object-side surface S7 of the fourth lens element L4 near the optical axis and near the circumference is concave. The image-side surface S8 of the fourth lens element L4 near the optical axis is convex, and the image-side surface S8 near the circumference is concave.

[0127] The fifth lens element L5 has negative refractive power. The object-side surface S9 of the fifth lens element L5 in the near-optical-axis area is convex, and the object-side surface S9 in the near-circumferential area is concave. The image-side surface S10 of the fifth lens element L5 in the near-optical-axis area is concave, and the image-side surface S10 in the near-circumferential area is convex.

[0128] The sixth lens element L6 has positive refractive power. The object-side surface S11 of the sixth lens element L6 in the near-optical-axis region is convex, and the object-side surface S11 in the near-circumferential region is concave. The image-side surface S12 of the sixth lens element L6 in the near-optical-axis region and the near-circumferential region is convex.

[0129] The seventh lens element L7 has negative refractive power. The object-side surface S13 of the seventh lens element L7 in the near-optical-axis region is convex, and the object-side surface S13 in the near-circumferential region is concave. The image-side surface S14 of the seventh lens element L7 in the near-optical-axis region is concave, and the image-side surface S14 in the near-circumferential region is convex.

[0130] The other structures of the fourth embodiment are the same as those of the first embodiment, and can be used as a reference.

[0131] Table 4a shows a table of characteristics of the optical system of this embodiment, wherein the data are obtained using light with a wavelength of 546 nm, and the units of Y radius, thickness and focal length are all millimeters (mm).

[0132] Table 4a

[0133]

[0134] The meanings of the parameters in Table 4a are the same as those in the first embodiment.

[0135] Table 4b gives the high-order coefficients of the aspheric mirror surfaces that can be used in the fourth embodiment, wherein the aspheric surface shapes can be defined by the formula given in the first embodiment.

[0136] Table 4b

[0137]

[0138] Figure 4b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fourth embodiment are shown. Figure 4b It can be seen that the optical system provided in the fourth embodiment can achieve good imaging quality.

[0139] Fifth embodiment

[0140] Please refer to Figure 5a and Figure 5b The optical system of this embodiment includes, in order from the object side to the image side along the optical axis:

[0141] The first lens element L1 has positive refractive power. The object-side surface S1 of the first lens element L1 near the optical axis and near the periphery is convex. The image-side surface S2 of the first lens element L1 near the optical axis is concave, and the image-side surface S2 near the periphery is convex.

[0142] The second lens element L2 has negative refractive power. The object-side surface S3 of the second lens element L2 near the optical axis and near the periphery is convex, and the image-side surface S4 of the second lens element L2 near the optical axis and near the periphery is concave.

[0143] The third lens L3 has positive refractive power. The object-side surface S5 of the third lens L3 near the optical axis and near the periphery is convex. The image-side surface S6 of the third lens L3 near the optical axis and near the periphery is convex.

[0144] The fourth lens element L4 has positive refractive power. The object-side surface S7 of the fourth lens element L4 near the optical axis and near the circumference is concave. The image-side surface S8 of the fourth lens element L4 near the optical axis is convex, and the image-side surface S8 near the circumference is concave.

[0145] The fifth lens element L5 has negative refractive power. The object-side surface S9 of the fifth lens element L5 near the optical axis and near the circumference is concave; the image-side surface S10 of the fifth lens element L5 near the optical axis and near the circumference is convex.

[0146] The sixth lens element L6 has positive refractive power. The object-side surface S11 of the sixth lens element L6 in the near-optical-axis region is convex, and the object-side surface S11 in the near-circumferential region is concave. The image-side surface S12 of the sixth lens element L6 in the near-optical-axis region is concave, and the image-side surface S12 in the near-circumferential region is convex.

[0147] The seventh lens element L7 has negative refractive power. The object-side surface S13 of the seventh lens element L7 in the near-optical-axis region is convex, and the object-side surface S13 in the near-circumferential region is concave. The image-side surface S14 of the seventh lens element L7 in the near-optical-axis region is concave, and the image-side surface S14 in the near-circumferential region is convex.

[0148] The other structures of the fifth embodiment are the same as those of the first embodiment, and can be used as a reference.

[0149] Table 5a shows a table of characteristics of the optical system of this embodiment, wherein the data are obtained using light with a wavelength of 546 nm, and the units of Y radius, thickness and focal length are all millimeters (mm).

[0150] Table 5a

[0151]

[0152] The meanings of the parameters in Table 5a are the same as those in the first embodiment.

[0153] Table 5b gives the high-order coefficients of each aspherical mirror surface that can be used in the fifth embodiment, wherein each aspherical surface shape can be defined by the formula given in the first embodiment.

[0154] Table 5b

[0155]

[0156] Figure 5b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the fifth embodiment are shown. The reference wavelength of the light of the astigmatism curve and the distortion curve is 546nm. Figure 5b It can be seen that the optical system provided in the fifth embodiment can achieve good imaging quality.

[0157] Sixth embodiment

[0158] Please refer to Figure 6a and Figure 6b The optical system of this embodiment includes, in order from the object side to the image side along the optical axis:

[0159] The first lens element L1 has positive refractive power. The object-side surface S1 of the first lens element L1 near the optical axis and near the periphery is convex. The image-side surface S2 of the first lens element L1 near the optical axis is concave, and the image-side surface S2 near the periphery is convex.

[0160] The second lens element L2 has negative refractive power. The object-side surface S3 of the second lens element L2 near the optical axis and near the periphery is convex, and the image-side surface S4 of the second lens element L2 near the optical axis and near the periphery is concave.

[0161] The third lens L3 has positive refractive power. The object-side surface S5 of the third lens L3 near the optical axis and near the periphery is convex. The image-side surface S6 of the third lens L3 near the optical axis is concave, and the image-side surface S6 near the periphery is convex.

[0162] The fourth lens element L4 has positive refractive power. The object-side surface S7 of the fourth lens element L4 near the optical axis and near the circumference is concave. The image-side surface S8 of the fourth lens element L4 near the optical axis is convex, and the image-side surface S8 near the circumference is concave.

[0163] The fifth lens element L5 has negative refractive power. The object-side surface S9 of the fifth lens element L5 in the near-optical-axis area is convex, and the object-side surface S9 in the near-circumferential area is concave. The image-side surface S10 of the fifth lens element L5 in the near-optical-axis area is concave, and the image-side surface S10 in the near-circumferential area is convex.

[0164] The sixth lens element L6 has positive refractive power. The object-side surface S11 of the sixth lens element L6 in the near-optical-axis region is convex, and the object-side surface S11 in the near-circumferential region is concave. The image-side surface S12 of the sixth lens element L6 in the near-optical-axis region and the near-circumferential region is convex.

[0165] The seventh lens element L7 has negative refractive power. The object-side surface S13 of the seventh lens element L7 in the near-optical-axis region is convex, and the object-side surface S13 in the near-circumferential region is concave. The image-side surface S14 of the seventh lens element L7 in the near-optical-axis region is concave, and the image-side surface S14 in the near-circumferential region is convex.

[0166] The other structures of the sixth embodiment are the same as those of the first embodiment, and can be used as a reference.

[0167] Table 6a shows a table of characteristics of the optical system of this embodiment, wherein the data are obtained using light with a wavelength of 546 nm, and the units of Y radius, thickness and focal length are all millimeters (mm).

[0168] Table 6a

[0169]

[0170] The meanings of the parameters in Table 6a are the same as those in the first embodiment.

[0171] Table 6b gives the high-order coefficients of each aspheric mirror surface that can be used in the sixth embodiment, wherein each aspheric surface shape can be defined by the formula given in the first embodiment.

[0172] Table 6b

[0173]

[0174] Figure 6b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the sixth embodiment are shown. The reference wavelength of the light of the astigmatism curve and the distortion curve is 546nm. Figure 6b It can be seen that the optical system provided in the sixth embodiment can achieve good imaging quality.

[0175] Seventh embodiment

[0176] Please refer to Figure 7a and Figure 7b The optical system of this embodiment includes, in order from the object side to the image side along the optical axis:

[0177] The first lens element L1 has positive refractive power. The object-side surface S1 of the first lens element L1 near the optical axis and near the periphery is convex. The image-side surface S2 of the first lens element L1 near the optical axis is concave, and the image-side surface S2 near the periphery is convex.

[0178] The second lens element L2 has negative refractive power. The object-side surface S3 of the second lens element L2 near the optical axis and near the periphery is convex, and the image-side surface S4 of the second lens element L2 near the optical axis and near the periphery is concave.

[0179] The third lens L3 has positive refractive power. The object-side surface S5 of the third lens L3 near the optical axis and near the periphery is convex. The image-side surface S6 of the third lens L3 near the optical axis is concave, and the image-side surface S6 near the periphery is convex.

[0180] The fourth lens element L4 has positive refractive power. The object-side surface S7 of the fourth lens element L4 near the optical axis and near the circumference is concave. The image-side surface S8 of the fourth lens element L4 near the optical axis is convex, and the image-side surface S8 near the circumference is concave.

[0181] The fifth lens element L5 has negative refractive power. The object-side surface S9 of the fifth lens element L5 in the near-optical-axis area is convex, and the object-side surface S9 in the near-circumferential area is concave. The image-side surface S10 of the fifth lens element L5 in the near-optical-axis area is concave, and the image-side surface S10 in the near-circumferential area is convex.

[0182] The sixth lens element L6 has positive refractive power. The object-side surface S11 of the sixth lens element L6 in the near optical axis region and near the circumference region is concave; the image-side surface S12 of the sixth lens element L6 in the near optical axis region and near the circumference region is convex.

[0183] The seventh lens element L7 has negative refractive power. The object-side surface S13 of the seventh lens element L7 in the near optical axis region and near the peripheral region is convex. The image-side surface S14 of the seventh lens element L7 in the near optical axis region is concave, and the image-side surface S14 in the near peripheral region is convex.

[0184] The other structures of the seventh embodiment are the same as those of the first embodiment, and can be used as a reference.

[0185] Table 7a shows a table of characteristics of the optical system of this embodiment, wherein the data are obtained using light with a wavelength of 546 nm, and the units of Y radius, thickness and focal length are all millimeters (mm).

[0186] Table 7a

[0187]

[0188] The meanings of the parameters in Table 7a are the same as those in the first embodiment.

[0189] Table 7b gives the high-order coefficients of each aspheric mirror surface that can be used in the seventh embodiment, wherein the surface shape of each aspheric surface can be defined by the formula given in the first embodiment.

[0190] Table 7b

[0191]

[0192] Figure 7b The longitudinal spherical aberration curve, astigmatism curve and distortion curve of the optical system of the seventh embodiment are shown. The reference wavelength of the light of the astigmatism curve and the distortion curve is 546nm. Figure 7b It can be seen that the optical system provided in the seventh embodiment can achieve good imaging quality.

[0193] Table 8 shows the values ​​of f / EPD, TTL / (ImgH*2), f13 / f, (|SAG71|+CT7+SAG72) / CT7, n12 / R12, (ET1+ET2+ET3) / (CT1+CT2+CT3), |f45 / f3|, and |f6 / R61| of the optical systems in the first to seventh embodiments.

[0194] Table 8

[0195]

[0196]

[0197] It can be seen from Table 8 that the optical systems of the first to seventh embodiments all satisfy the following conditional expressions: 1.35<f / EPD≤1.75, 0.6<TTL / (ImgH*2)<0.8, 0.8<f13 / f<1.1, 1.6<(|SAG71|+CT7+SAG72) / CT7<3.3, 0.2<n12 / R12≤0.4, 0.63≤(ET1+ET2+ET3) / (CT1+CT2+CT3)≤0.75, 1.75≤|f45 / f3|<41, |f6 / R61|<22.

[0198] The above disclosure is only a preferred embodiment of the present invention, and certainly cannot be used to limit the scope of the rights of the present invention. Ordinary technicians in this field can understand that all or part of the processes of the above embodiment and equivalent changes made in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. An optical system, characterized in that: The optical system has seven lenses with refractive power, which include the following lenses from the object side to the image side along the optical axis: A first lens element having positive refractive power, wherein the object-side surface of the first lens element in the near optical axis region and the near circumference region is convex, and the image-side surface of the first lens element in the near optical axis region is concave; The second lens has negative refractive power, the object-side surface of the second lens near the optical axis is convex, and the image-side surface of the second lens near the optical axis is concave; A third lens element has positive refractive power, and the object side surfaces of the third lens element near the optical axis and near the circumference are convex; A fourth lens element having refractive power, wherein the object-side surface of the fourth lens element in a near optical axis region is concave, and the image-side surface of the fourth lens element in a near optical axis region is convex; a fifth lens element having refractive power, wherein the object-side surface and the image-side surface of the near-circumferential region of the fifth lens element are convex surfaces, the object-side surface and the image-side surface of the fifth lens element are both aspherical surfaces, and at least one of the object-side surface and the image-side surface of the fifth lens element is provided with at least one inflection point; a sixth lens having refractive power; a seventh lens element having negative refractive power, wherein the object-side surface of the seventh lens element in a near optical axis region is convex, the image-side surface of the seventh lens element in a near optical axis region is concave, both the object-side surface and the image-side surface of the seventh lens element are aspherical, and at least one of the object-side surface and the image-side surface of the seventh lens element is provided with at least one inflection point; The optical system satisfies the conditional formula: 1.35≤f / EPD≤1.75; 1.75≤|f45 / f3|<41; 0.8<f13 / f<1.1; Wherein, f is the effective focal length of the optical system, EPD is the entrance pupil diameter of the optical system, f45 is the combined effective focal length of the fourth lens and the fifth lens, f3 is the effective focal length of the third lens, f13 is the combined effective focal length of the first lens, the second lens and the third lens, and f is the effective focal length of the optical system.

2. The optical system according to claim 1, wherein The image side surface of the near-circumferential region of the second lens is a concave surface, the object side surface of the near-circumferential region of the sixth lens is a concave surface, and the image side surface of the near-circumferential region of the sixth lens is a convex surface. Both the object side surface and the image side surface of the sixth lens are aspherical surfaces, and at least one of the object side surface and the image side surface of the sixth lens is provided with at least one inflection point.

3. The optical system according to claim 1 or 2, wherein: The first lens is a glass lens, and both the object-side surface and the image-side surface of the first lens are aspherical surfaces. The first lens satisfies the conditional formula: n12＞1.7； Wherein, n12 is the refractive index of the first lens for light with a wavelength of 546 nm.

4. The optical system according to claim 1 or 2, wherein: The optical system satisfies the conditional formula: 74.7°≤FOV≤85°; Wherein, FOV is the maximum field of view angle of the optical system in the diagonal direction.

5. The optical system according to claim 1 or 2, wherein: The optical system satisfies the conditional formula: 0.6<TTL / (ImgH*2)≤0.76; Wherein, TTL is the distance from the object side surface of the first lens to the imaging surface of the optical system on the optical axis, and ImgH is half of the diagonal length of the effective photosensitive area of ​​the optical system.

6. The optical system according to claim 1 or 2, wherein: The optical system satisfies the conditional formula: 1.6<(|SAG71|+CT7+SAG72) / CT7<3.3; Among them, SAG71 is the maximum sag of the object side surface of the seventh lens, CT7 is the thickness of the seventh lens on the optical axis, and SAG72 is the maximum sag of the image side surface of the seventh lens.

7. The optical system according to claim 1 or 2, wherein: The optical system satisfies the conditional formula: 0.2<n12 / R12≤0.4; Wherein, n12 is the refractive index of the first lens for light with a wavelength of 546 nm, and R12 is the curvature radius of the image side surface of the first lens at the optical axis.

8. The optical system according to claim 1 or 2, wherein: The optical system satisfies the conditional formula: 0.63≤(ET1+ET2+ET3) / (CT1+CT2+CT3)<1; Wherein, ET1 is the thickness of the edge of the optically effective area of ​​the first lens, ET2 is the thickness of the edge of the optically effective area of ​​the second lens, ET3 is the thickness of the edge of the optically effective area of ​​the third lens, CT1 is the thickness of the first lens on the optical axis, CT2 is the thickness of the second lens on the optical axis, and CT3 is the thickness of the third lens on the optical axis.

9. The optical system according to claim 1 or 2, wherein: The optical system satisfies the conditional formula: |f6 / R61|<22; Wherein, f6 is the effective focal length of the sixth lens element, and R61 is the radius of curvature of the object side surface of the sixth lens element at the optical axis.

10. The optical system according to claim 1 or 2, wherein: The optical system satisfies the conditional formula: 70°≤FOV≤85°; Wherein, FOV is the maximum field of view angle of the optical system in the diagonal direction.

11. A lens module, characterized in that: The optical system comprises a lens barrel, an electronic photosensitive element, and the optical system according to any one of claims 1 to 10, wherein the first lens to the seventh 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.

12. An electronic device, characterized in that: It comprises a shell and the lens module as claimed in claim 11, wherein the lens module is arranged in the shell.

Images