CN113391429B

CN113391429B - Optical system, camera module and electronic equipment

Info

Publication number: CN113391429B
Application number: CN202110576219.6A
Authority: CN
Inventors: 曾晗; 李明
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2021-05-26
Filing date: 2021-05-26
Publication date: 2022-08-30
Anticipated expiration: 2041-05-26
Also published as: CN113391429A

Abstract

The embodiment of the application discloses optical system, camera module and electronic equipment. The optical system comprises a first lens and a third lens with positive refractive power, a second lens and a fifth lens with negative refractive power, and a fourth lens and a sixth lens with refractive power. The object-side surface of the first lens element is convex at the paraxial region, the image-side surface of the first lens element is concave at the paraxial region, the object-side surface and the image-side surface of the second lens element are both concave at the paraxial region, the object-side surface of the fourth lens element is concave at the paraxial region, the object-side surface of the fifth lens element is concave at the paraxial region, and the object-side surface of the sixth lens element is convex at the paraxial region. The optical system satisfies: 1.2mm- ¹ <tan(HFOV)/SD11<1.5mm‑ ¹ . The optical system has the characteristics of miniaturization, lightness and thinness by reasonably configuring the refractive power of the first lens element to the sixth lens element, the surface types of the first lens element, the second lens element, the fourth lens element, the fifth lens element and the sixth lens element and limiting the range of tan (HFOV)/SD 11.

Description

Optical system, camera module and electronic equipment

Technical Field

The application belongs to the technical field of optical imaging, and particularly relates to an optical system, a camera module and electronic equipment.

Background

In recent years, with the trend of thinning and lightening electronic devices such as smart phones, flat panels, and cameras, the demand for thinning and lightening optical systems is increasing.

At present, although the four-piece or five-piece optical system can meet the requirement of light and thin, the four-piece or five-piece optical system has limitations in the aspects of refractive power distribution, aberration astigmatism correction, sensitivity distribution and the like, and cannot further meet the imaging requirement of higher specification. For this reason, the resolution can be improved by increasing the number of lenses of the optical system, however, this is disadvantageous for the lightness and thinness of the optical system.

Therefore, it is desirable to design a light and thin optical system that can meet the high-specification imaging requirements.

Disclosure of Invention

The embodiment of the application provides an optical system, a camera module and an electronic device, wherein the optical system has the characteristics of being light and thin and has good imaging quality.

In a first aspect, an optical system includes a plurality of lenses, each of the plurality of lenses includes a first lens element with positive refractive power arranged in order from an object side (the object side refers to a side on which light is incident) to an image side (the image side refers to a side on which light is emitted), an object side surface of the first lens element is convex at a paraxial region, and an image side surface of the first lens element is concave at the paraxial region; the second lens element with negative refractive power has a concave object-side surface and a concave image-side surface at a paraxial region; a third lens element with positive refractive power; a fourth lens element with refractive power having a concave object-side surface at a paraxial region and a convex image-side surface at a paraxial region; a fifth lens element with negative refractive power having a concave object-side surface at paraxial region; the sixth lens element with refractive power has a convex object-side surface at a paraxial region thereof and a concave image-side surface at a paraxial region thereof. It is understood that the fourth lens element and the sixth lens element with refractive power have both positive and negative refractive powers. The optical system satisfies the following conditional expression: 1.2mm ^-1 <tan(HFOV)/SD11<1.5mm ^-1 Tan (hfov) is a tangent value of half of the maximum field angle of the optical system, and SD11 is half of the maximum effective aperture of the object-side surface of the first lens.

The refractive power is the focal power, and represents the ability of the optical system to deflect light, positive refractive power represents the converging effect of the lens on the light beam, and negative refractive power represents the diverging effect of the lens on the light beam. When the lens has no refractive power, that is, when the focal power is zero, the lens is plane refraction, and at this time, the axially parallel light beams are still axially parallel light beams after being refracted, and the refraction phenomenon does not occur.

The optical system has the characteristics of miniaturization, lightness and thinness and good imaging quality by reasonably configuring the refractive power from the first lens to the sixth lens in the optical system, the surface shapes of the first lens, the second lens, the fourth lens, the fifth lens and the sixth lens and limiting the range of tan (HFOV)/SD 11.

Specifically, the arrangement that the first lens element provides positive refractive power for the optical system is favorable for improving the aberration correction capability of the first lens element, and the arrangement that the object-side surface of the first lens element is convex at the paraxial region and the image-side surface thereof is concave at the paraxial region can ensure that the first lens element has a proper thickness, so that the first lens element can be reasonably matched with the rear lens element during assembly; the second lens has stronger negative refractive power and the biconcave design, so that the second lens is favorable for providing proper negative refractive power for an optical system, the spherical aberration generated by the first lens is favorably corrected, the miniaturization of the system is realized, and the biconcave design can also avoid the light rays collected by the first lens from being deflected at a large angle, so that the smooth transmission of the light rays is realized; the third lens is set to be a lens with stronger positive refractive power, and the refractive power of the third lens is matched with that of the first lens and that of the second lens, so that the miniaturization design of the optical system is facilitated; the fourth lens element has weaker positive or negative refractive power, and spherical aberration, coma aberration and spherical aberration generated by the front lens element can be well corrected through reasonable design of the surface shape, so that the correction burden of the rear lens element is reduced; the fifth lens element with strong negative refractive power can share the burden of the negative refractive power of the second lens element, and the fifth lens element with strong negative refractive power can cooperate with the second lens element with strong negative refractive power to shorten the total optical length, thereby realizing miniaturization, lightness and thinness of the optical system; the sixth lens element with refractive power has a convex object-side surface at the paraxial region and a concave image-side surface at the paraxial region, and the meniscus design can easily ensure the back focus of the system, thereby shortening the total optical length, realizing the miniaturization design of the system, and simultaneously enabling the light to be smoothly transmitted to the imaging surface, and effectively correcting spherical aberration, coma aberration and spherical aberration generated by the front lens elements.

By limiting the range of tan (hfov)/SD11, the optical system has a large angle of view, and is advantageous in increasing the amount of light entering the optical system and improving the imaging quality under weak light, thereby achieving an optical system that is both compact and has good imaging quality. When tan (HFOV)/SD11<1.2mm ^-1 In addition, the maximum effective aperture of the object-side surface of the first lens is smaller than that of the second lensToo large, which is not conducive to miniaturization of the optical system; when tan (HFOV)/SD11>1.5mm ^-1 In the case of a large viewing angle, the system is prone to produce dark angles at the edge viewing field, which affects the imaging quality, and it is difficult to control the total length of the optical system within a small range in a large viewing angle range, which is not conducive to miniaturization and light weight of the optical system.

In a possible embodiment, the optical system satisfies the conditional expression: 1.3< f12/f <1.6, f12 being the combined focal length of the first and second lenses, f being the effective focal length of the optical system. By limiting the range of f12/f, the combined focal length of the first lens element and the second lens element and the effective focal length of the optical system are reasonably configured, so that the refractive power strength of the first lens element and the second lens element closest to the object side is appropriate, which is beneficial to improving the field curvature and distortion of the optical system, and the reasonable refractive power strength can also reduce the molding and processing difficulty of the lens elements, so that the system has a short-focus characteristic due to the reasonable overall refractive power, thereby being beneficial to shortening the total length of the optical system and realizing miniaturization. When f12/f is not less than 1.6 or f12/f is not more than 1.3, the total refractive power of the first lens element and the second lens element is too small or too large, which is not favorable for correcting aberration.

In a possible embodiment, the optical system satisfies the conditional expression: 0.4< f2/R21<3, f2 is the focal length of the second lens, and R21 is the radius of curvature of the object-side surface of the second lens at the optical axis. By limiting the range of f2/R21, the second lens can balance the spherical aberration generated by the first lens, and realize good imaging quality, in addition, the negative refractive power of the second lens is beneficial to the divergence of light rays, the field angle of an optical system can be further enlarged, the gentle object side surface is also convenient to reduce the tolerance sensitivity of the lens, and further the total length of the system is shortened. When f2/R21 is less than 0.4, the negative refractive power provided by the second lens is too strong, so that light rays are excessively dispersed, the total length of the system is not shortened, and the aberration generated by the first lens is easily corrected excessively, so that the imaging quality is reduced; when f2/R4 > 3, the negative refractive power of the second lens element is insufficient, spherical aberration and aberration are difficult to correct in the system, and the object-side surface of the second lens element is too curved, which makes the lens tolerance sensitive.

In a possible embodiment, the optical system satisfies the conditional expression: 0.8< | (R51+ R52)/(R51-R52) | <2.2, R51 is a radius of curvature of an object-side surface of the fifth lens at an optical axis, and R52 is a radius of curvature of an image-side surface of the fifth lens at the optical axis. By limiting the range of | (R51+ R52)/(R51-R52) |, the curvature radius of the object-side surface of the fifth lens and the curvature radius of the image-side surface of the fifth lens can be configured appropriately, so that the shape of the fifth lens is not too curved, the lens is convenient to form and process, astigmatism and aberration of the system are favorably corrected, aberration sensitivity of the system is reduced, and the product yield is favorably improved.

In one possible embodiment, the optical system satisfies the conditional expression: 0.8< CT6/| SAG61| <2.1, CT6 is the thickness of the sixth lens on the optical axis, SAG61 is the rise of the object-side surface of the sixth lens at the maximum effective half aperture. By limiting the range of CT6/| SAG61|, the shape of the sixth lens is well controlled, the manufacturing and molding of the lens are facilitated, and the defect of poor molding is reduced. In addition, the field curvature generated by the first lens to the fifth lens can be corrected, so that the balance of the field curvature of the system is ensured, namely the field curvature of different fields tends to be balanced, the image quality of the whole system picture is uniform, and the imaging quality of the optical system is improved. When CT6/| SAG61| < 0.8, the surface profile of the object-side surface of the sixth lens at the circumference is excessively curved, which easily causes poor lens molding and affects the manufacturing yield. When CT6/| SAG61| > 2.1, the surface shape of the object side surface of the sixth lens at the circumference is too smooth, the deflection capability of the light rays of the off-axis field is insufficient, and the distortion, the curvature of field and the aberration of the marginal field are not corrected favorably, so that the imaging quality of the optical system is influenced.

In a possible embodiment, the optical system satisfies the conditional expression: 0.15< FFL/f <0.3, wherein FFL is the shortest distance from the image side surface of the sixth lens element to the imaging surface in the optical axis direction, and f is the effective focal length of the optical system. By limiting the range of FFL/f, a sufficient focusing range can be secured between the image-side surface of the sixth lens and the photosensitive element while the optical system is kept compact. When FFL/f is less than 0.15, the back focus of the optical system is too small, which tends to cause too large incident angle of light reaching the image forming surface, affecting the light receiving efficiency of the photosensitive element, and reducing the image forming quality, and when FFL/f is greater than 0.3, the back focus of the optical system is too large, making it difficult to shorten the total length of the optical system, and not beneficial to the miniaturization of the optical system.

In a possible embodiment, the optical system satisfies the conditional expression: 1.9< TTL/ctal <2.2, wherein TTL is the distance between the object side surface of the first lens and the imaging surface on the optical axis, and ctal is the sum of the thicknesses of the first lens and the sixth lens on the optical axis. By limiting the range of TTL/ctal, the total length of the optical system is effectively shortened, the whole length of the optical system can be compressed, and the lens structure is more compact. By reasonably configuring the sizes and the intervals of the first lens, the second lens and the third lens, the miniaturization, the lightness and the thinness of an optical system can be realized under the condition of meeting the requirements of high pixels and high imaging quality.

In one possible embodiment, the optical system satisfies the conditional expression: 1.25< TTL/Imgh <1.41, where TTL is the distance on the optical axis from the object-side surface of the first lens element to the image forming surface, and Imgh is half the image height corresponding to the maximum field angle of the optical system. By limiting the range of TTL/Imgh, the large image plane characteristic of the optical system can be realized, thereby ensuring the imaging quality of the optical system, effectively shortening the total length of the optical system and realizing the miniaturization and ultrathin of the optical system. When TTL/Imgh is less than 1.25, the thickness of each lens in the optical system is thin, which is not beneficial to the manufacture and processing of the lens, increases the sensitivity of the system and reduces the production yield of the lens; when TTL/Imgh >1.41, the total length of the optical system is too large, which is not advantageous for miniaturization of the optical system.

In a second aspect, the present application provides a camera module, including a photosensitive element and the optical system of any one of the foregoing embodiments, where the photosensitive element is located on an image side of the optical system.

In a third aspect, the present application provides an electronic device, which includes a fixing member and the camera module, where the camera module is disposed on the fixing member. The fixing member may be a motor, such as a voice coil motor, and may also be other fixing devices.

By properly configuring the refractive powers of the first lens element to the sixth lens element and the surface shapes of the first lens element, the second lens element, the fourth lens element, the fifth lens element and the sixth lens element in the optical system, and limiting the tan (HFOV)/SD11 range, the optical system has the characteristics of miniaturization, lightness and thinness and has good imaging quality.

Drawings

In order to more clearly illustrate the technical solutions in the embodiments or the background art of the present application, the drawings required to be used in the embodiments or the background art of the present application will be described below.

FIG. 1 is a schematic diagram of an optical system according to a first embodiment of the present application;

fig. 2 is a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the first embodiment;

FIG. 3 is a schematic diagram of an optical system according to a second embodiment of the present application;

fig. 4 is a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the second embodiment;

FIG. 5 is a schematic diagram of an optical system according to a third embodiment of the present application;

fig. 6 is a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the third embodiment;

FIG. 7 is a schematic diagram of an optical system according to a fourth embodiment of the present application;

fig. 8 is a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the fourth embodiment;

fig. 9 is a schematic structural diagram of an optical system provided in a fifth embodiment of the present application;

fig. 10 is a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the fifth embodiment;

fig. 11 is a schematic diagram of an optical system provided in the present application applied to an electronic device.

Detailed Description

The embodiments of the present application will be described below with reference to the drawings.

An optical system provided by the present application includes six lenses, which are, in order from an object side to an image side, a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens.

Specifically, the surface shapes and refractive powers of the six lenses are as follows:

a first lens element with positive refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; the second lens element with negative refractive power has a concave object-side surface and a concave image-side surface at a paraxial region; a third lens element with positive refractive power; a fourth lens element with refractive power having a concave object-side surface at a paraxial region and a convex image-side surface at a paraxial region; a fifth lens element with negative refractive power having a concave object-side surface at paraxial region; the sixth lens element with refractive power has a convex object-side surface at a paraxial region thereof and a concave image-side surface at a paraxial region thereof. It is to be understood that the fourth lens element and the sixth lens element with refractive power have both positive and negative refractive powers.

The optical system satisfies the following conditional expression: 1.2mm ^-1 <tan(HFOV)/SD11<1.5mm ^-1 Tan (hfov) is a tangent value of half of the maximum field angle of the optical system, and SD11 is half of the maximum effective aperture of the object-side surface of the first lens.

The optical system has the characteristics of miniaturization, lightness and thinness and good imaging quality by reasonably configuring the refractive power from the first lens to the sixth lens in the optical system and the surface shapes of the first lens, the second lens, the fourth lens, the fifth lens and the sixth lens and limiting the range of tan (HFOV)/SD 11.

Specifically, the arrangement that the first lens element provides positive refractive power for the optical system is favorable for improving the aberration correction capability of the first lens element, and the arrangement that the object-side surface of the first lens element is convex at the paraxial region and the image-side surface thereof is concave at the paraxial region can ensure that the first lens element has a proper thickness, so that the first lens element can be reasonably matched with the rear lens element during assembly; the second lens has stronger negative refractive power and the biconcave design, so that the second lens is favorable for providing proper negative refractive power for an optical system, the spherical aberration generated by the first lens is favorably corrected, the miniaturization of the system is realized, and the biconcave design can also avoid the light rays collected by the first lens from being deflected at a large angle, so that the smooth transmission of the light rays is realized; the third lens is set to be a lens with stronger positive refractive power, and the refractive power of the third lens is matched with that of the first lens and that of the second lens, so that the miniaturization design of an optical system is facilitated; the fourth lens element has weaker positive or negative refractive power, and spherical aberration, coma aberration and spherical aberration generated by the front lens element can be well corrected through reasonable design of the surface shape, so that the correction burden of the rear lens element is reduced; the fifth lens element with strong negative refractive power can share the burden of the negative refractive power of the second lens element, and the fifth lens element with strong negative refractive power can cooperate with the second lens element with strong negative refractive power to shorten the total optical length, thereby realizing miniaturization and lightness of the optical system; the sixth lens element with refractive power has a convex object-side surface at the paraxial region and a concave image-side surface at the paraxial region, and the meniscus design can easily ensure the back focus of the system, thereby shortening the total optical length, realizing the miniaturization design of the system, and simultaneously enabling the light to be smoothly transmitted to the imaging surface, and effectively correcting spherical aberration, coma aberration and spherical aberration generated by the front lens elements.

By limiting the range of tan (hfov)/SD11, the optical system has a large angle of view, and is advantageous in increasing the amount of light entering the optical system and improving the imaging quality under weak light, thereby achieving an optical system that is both compact and has good imaging quality. When tan (HFOV)/SD11<1.2mm ^-1 In the meantime, the field of view of the optical system is narrow, the light input is small, and the condition of weak illumination is not favorableIn addition, the maximum effective aperture of the object-side surface of the first lens is too large, which is not beneficial to realizing the miniaturization of the optical system; when tan (HFOV)/SD11>1.5mm ^-1 In the case of a large viewing angle, the system is prone to produce dark angles at the edge viewing field, which affects the imaging quality, and it is difficult to control the total length of the optical system within a small range in a large viewing angle range, which is not conducive to miniaturization and light weight of the optical system.

In a possible embodiment, the optical system satisfies the conditional expression: 1.3< f12/f <1.6, f12 being the combined focal length of the first and second lenses, f being the effective focal length of the optical system. By limiting the range of f12/f and reasonably configuring the combined focal length of the first lens and the second lens and the effective focal length of the optical system, the refractive power strength of the first lens and the second lens closest to the object side is appropriate, which is beneficial to improving the field curvature and distortion of the optical system, and the reasonable refractive power strength can also reduce the molding and processing difficulty of the lenses, so that the system has a short-focus characteristic due to the reasonable overall refractive power, and is further beneficial to shortening the total length of the optical system and realizing miniaturization. When f12/f is not less than 1.6 or f12/f is not more than 1.3, the total refractive power of the first lens element and the second lens element is too small or too large, which is not favorable for correcting aberration.

In one possible embodiment, the optical system satisfies the conditional expression: 0.4< f2/R21<3, f2 is the focal length of the second lens, and R21 is the radius of curvature of the object-side surface of the second lens at the optical axis. By limiting the range of f2/R21, the second lens element can balance the spherical aberration generated by the first lens element, thereby achieving good imaging quality, and the negative refractive power of the second lens element is beneficial to the divergence of light rays, thereby further enlarging the field angle of the optical system, facilitating the reduction of tolerance sensitivity of the lens due to the gentle object-side surface, and further shortening the total length of the system. When f2/R21 is less than 0.4, the negative refractive power provided by the second lens is too strong, so that light rays are excessively dispersed, the total length of the system is not shortened, and the aberration generated by the first lens is easily corrected excessively, so that the imaging quality is reduced; when f2/R4 > 3, the negative refractive power of the second lens element is insufficient, spherical aberration and aberration are difficult to correct in the system, and the object-side surface of the second lens element is too curved, which makes the lens tolerance sensitive.

In a possible embodiment, the optical system satisfies the conditional expression: 0.8< CT6/| SAG61| <2.1, CT6 is the thickness of the sixth lens on the optical axis, SAG61 is the rise of the object-side surface of the sixth lens at the maximum effective half aperture. By limiting the range of CT6/| SAG61|, the shape of the sixth lens is well controlled, the manufacturing and molding of the lens are facilitated, and the defect of poor molding is reduced. In addition, the field curvature generated by the first lens to the fifth lens can be corrected, so that the balance of the field curvature of the system is ensured, namely the field curvature of different fields tends to be balanced, the image quality of the whole system picture is uniform, and the imaging quality of the optical system is improved. When CT6/| SAG61| < 0.8, the surface shape of the object-side surface of the sixth lens at the circumference is excessively curved, which easily causes poor lens molding and affects the manufacturing yield. When CT6/| SAG61| > 2.1, the surface shape of the object side surface of the sixth lens at the circumference is too smooth, the deflection capability of the light rays of the off-axis field is insufficient, and the distortion, the curvature of field and the aberration of the marginal field are not corrected favorably, so that the imaging quality of the optical system is influenced.

In a possible embodiment, the optical system satisfies the conditional expression: 0.15< FFL/f <0.3, wherein FFL is the shortest distance from the image side surface of the sixth lens element to the imaging surface in the optical axis direction, and f is the effective focal length of the optical system. By limiting the range of FFL/f, a sufficient focusing range can be secured between the image-side surface of the sixth lens and the photosensitive element while the optical system is kept compact. When FFL/f is less than 0.15, the back focus of the optical system is too small, which tends to cause too large an incident angle at which light reaches the image plane, affecting the efficiency of the photosensitive element to receive light, and reducing the image quality, and when FFL/f is greater than 0.3, the back focus of the optical system is too large, which makes it difficult to shorten the total length of the optical system, which is not favorable for miniaturization of the optical system.

In a possible embodiment, the optical system satisfies the conditional expression: 1.9< TTL/ctal <2.2, wherein TTL is the distance between the object side surface of the first lens and the imaging surface on the optical axis, and ctal is the sum of the thicknesses of the first lens and the sixth lens on the optical axis. By limiting the range of TTL/ctal, the total length of the optical system is effectively shortened, the whole length of the optical system can be compressed, and the lens structure is more compact. By reasonably configuring the sizes and the intervals of the first lens, the sixth lens and the fourth lens, the miniaturization, the lightness and the thinness of the optical system can be realized under the condition of meeting the requirements of high pixels and high imaging quality.

In a possible embodiment, the optical system satisfies the conditional expression: 1.25< TTL/Imgh <1.41, where TTL is the distance on the optical axis from the object-side surface of the first lens element to the image forming surface, and Imgh is half the image height corresponding to the maximum field angle of the optical system. By limiting the range of TTL/Imgh, the large image plane characteristic of the optical system can be realized, thereby ensuring the imaging quality of the optical system, effectively shortening the total length of the optical system and realizing the miniaturization and ultrathin of the optical system. When TTL/Imgh is less than 1.25, the thickness of each lens in the optical system is thin, which is not beneficial to the manufacture and processing of the lens, increases the sensitivity of the system and reduces the production yield of the lens; when TTL/Imgh >1.41, the total length of the optical system is too large, which is not advantageous for miniaturization of the optical system.

The present application is described in detail below with reference to five specific examples.

Example one

As shown in fig. 1, a straight line 11 indicates an optical axis, a side of the first lens L1 away from the second lens L2 is an object side 12, and a side of the sixth lens L6 away from the fifth lens L5 is an image side 13. The optical system provided in this embodiment includes, in order from the object side 12 to the image side 13, a stop STO, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and an infrared filter IRCF.

The first lens element L1 with positive refractive power has a convex object-side surface S1 at a paraxial region and a concave image-side surface S2 at a paraxial region, and is made of plastic material.

The second lens element L2 with negative refractive power is made of plastic, and has a concave object-side surface S3 and a concave image-side surface S4 at a paraxial region, which are both aspheric.

The third lens element L3 with positive refractive power is made of plastic, and has a convex object-side surface S5 and a convex image-side surface S6 at a paraxial region.

The fourth lens element L4 with positive refractive power has a concave object-side surface S7 at a paraxial region and a convex image-side surface S8 at a paraxial region, and is made of plastic material.

The fifth lens element L5 with negative refractive power is made of plastic material, and has a concave object-side surface S9 at a paraxial region and a convex image-side surface S10 at a paraxial region.

The sixth lens element L6 with negative refractive power is made of plastic, and has a convex object-side surface S11 at a paraxial region and a concave image-side surface S12 at a paraxial region.

Note that the lens material is not limited to a Plastic material, and in some embodiments, the material of at least one lens in the optical system is Plastic (PC), and the Plastic material may be polycarbonate, gum, or the like. In some embodiments, at least one lens of the optical system is made of Glass (GL). The lens made of plastic can reduce the production cost of the optical system, and the lens made of glass can endure higher or lower temperature and has excellent optical effect and better stability. In some embodiments, lenses of different materials may be disposed in the optical system, that is, a design combining a glass lens and a plastic lens may be adopted, but the specific configuration relationship may be determined according to practical requirements, and is not exhaustive here.

The stop STO may be located on the object side of the first lens L1 or between any two adjacent lenses, and the stop STO in the present embodiment is disposed on the object side of the first lens L1.

The infrared filter IRCF is arranged behind the sixth lens L6 and comprises an object side surface S13 and an image side surface S14, the infrared filter IRCF is used for filtering infrared rays, the rays incident to the imaging surface are visible rays, the wavelength of the visible rays is 380nm-780nm, and the infrared filter IRCF is made of glass.

The image forming surface S15 is a surface on which an image is formed by the light of the subject passing through the optical system.

Table 1a shows a characteristic table of the optical system of the present embodiment in which the radius of curvature in the present embodiment is the radius of curvature of each lens at the optical axis, and the reference wavelength of the refractive index and the abbe number is 587.6 nm. In addition, the first value in the "thickness" parameter column of the lens is the thickness of the lens on the optical axis, and the second value is the distance between the image side surface of the lens and the rear surface of the lens in the image side direction on the optical axis; the numerical value of the stop ST0 in the "thickness" parameter column is the distance on the optical axis from the stop ST0 to the vertex of the next surface (the vertex refers to the intersection point of the surface and the optical axis), and we default that the direction from the object side surface to the image side surface of the last lens of the first lens L1 is the positive direction of the optical axis, when the value is negative, it indicates that the stop ST0 is disposed on the right side of the vertex of the surface, and if the thickness of the stop STO is positive, the stop is on the left side of the vertex of the surface.

TABLE 1a

Wherein f is an effective focal length of the optical system, FNO is an f-number of the optical system, HFOV is a half of a maximum field angle of the optical system, and TTL is a distance on an optical axis from an object-side surface of the first lens to an image plane of the optical system.

In the present embodiment, the object-side surface and the image-side surface of the first lens L1 through the sixth lens L6 are aspheric, and the surface shape of each aspheric lens can be defined by, but is not limited to, the following aspheric formula:

wherein Z is a distance from a corresponding point on the aspherical surface to a plane tangent to the surface vertex, r is a distance from a corresponding point on the aspherical surface to the optical axis, c is a curvature of the aspherical surface vertex, k is a conic constant, and Ai is a coefficient corresponding to the i-th high-order term in the aspherical surface type formula.

Table 1b shows the high-order term coefficients a4, A6, a8, a10, a12, a14, a16, a18, and a20 that can be used for the respective aspherical mirror surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12 in the first embodiment.

TABLE 1b

Number of noodles

S1

S2

S3

S4

S5

S6

K

-2.3579E-01

-4.0754E+01

5.9520E+00

-2.7567E+01

-3.9959E+01

1.7169E+01

A4

6.7399E-02

2.9850E-02

-9.4172E-02

-2.3861E-02

-8.9178E-02

-2.3432E-01

A6

2.6959E-01

-2.4349E+00

-1.3161E+00

1.5909E+00

6.6375E-01

1.1177E-01

A8

-8.9949E+00

5.0870E+01

4.6143E+01

-1.0605E+01

-2.7137E+01

-1.1688E+01

A10

1.5859E+02

-5.8474E+02

-5.9013E+02

8.5518E+01

3.0370E+02

1.0442E+02

A12

-1.4083E+03

4.0567E+03

4.3853E+03

-4.1334E+02

-1.9576E+03

-5.4250E+02

A14

7.1365E+03

-1.7196E+04

-1.9869E+04

1.0057E+03

7.6928E+03

1.7940E+03

A16

-2.0786E+04

4.3392E+04

5.3730E+04

-5.2532E+02

-1.8142E+04

-3.6869E+03

A18

3.2424E+04

-5.9487E+04

-7.9410E+04

-2.2756E+03

2.3788E+04

4.3714E+03

A20

-2.0958E+04

3.3789E+04

4.9060E+04

3.2152E+03

-1.3374E+04

-2.2704E+03

Number of noodles

S7

S8

S9

S10

S11

S12

K

-1.4003E+01

-2.5195E+01

-3.5592E+01

9.1691E+01

-1.3807E+01

-2.7848E+00

A4

-1.1188E-01

9.4606E-02

2.0090E-01

-4.5727E-01

-3.5887E-01

-6.1407E-01

A6

-1.7493E+00

-8.9339E-02

9.2555E-01

3.0150E+00

-1.5139E+00

5.2439E-01

A8

3.4094E+00

-1.0055E+01

-8.1819E+00

-9.8234E+00

6.7070E+00

3.8081E-02

A10

5.1573E+00

5.3059E+01

1.8613E+01

1.6433E+01

-1.2741E+01

-4.9724E-01

A12

-2.2424E+01

-1.2190E+02

-1.7292E+01

-1.5284E+01

1.3633E+01

4.7342E-01

A14

2.4702E+01

1.5398E+02

1.4571E+00

7.7065E+00

-8.7290E+00

-2.2813E-01

A16

1.2298E+00

-1.1061E+02

9.7077E+00

-1.6572E+00

3.3209E+00

6.2514E-02

A18

-2.2424E+01

4.1941E+01

-7.0478E+00

-8.8906E-02

-6.9239E-01

-9.2828E-03

A20

1.1985E+01

-6.4016E+00

1.5738E+00

6.9199E-02

6.0902E-02

5.8138E-04

Fig. 2 shows a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the first embodiment. The longitudinal spherical aberration curve represents the deviation of convergence focuses of light rays with different wavelengths after passing through each lens of the optical system, and the reference wavelengths of the longitudinal spherical aberration curve are 656.2725nm, 587.5618nm, 546.0740nm, 486.1327nm and 435.8343 nm; the astigmatism curves represent meridional image surface curvature and sagittal image surface curvature, wherein S represents sagittal direction, T represents meridional direction, and the reference wavelength of the astigmatism curves is 546.0740 nm; the distortion curve represents the distortion magnitude values corresponding to different angles of view, and the reference wavelength of the distortion curve is 546.0740 nm. As can be seen from fig. 2, the optical system according to the first embodiment can achieve good imaging quality.

Example two

As shown in fig. 3, a straight line 11 indicates an optical axis, a side of the first lens L1 away from the second lens L2 is an object side 12, and a side of the sixth lens L6 away from the fifth lens L5 is an image side 13. In the optical system provided in this embodiment, the stop STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the infrared filter IRCF are arranged in order from the object side 12 to the image side 13.

The second lens element L2 with negative refractive power is made of plastic, and has an object-side surface S3 and an image-side surface S4 which are concave at a paraxial region and are aspheric.

The third lens element L3 with positive refractive power has a convex object-side surface S5 at a paraxial region and a convex image-side surface S6 at a paraxial region, and is made of plastic material.

The fourth lens element L4 with negative refractive power is made of plastic, and has a concave object-side surface S7 at a paraxial region and a convex image-side surface S8 at a paraxial region.

Table 2a shows a characteristic table of the optical system of the present embodiment, and definitions of parameters in the characteristic table can be obtained from the description of the foregoing embodiments, which are not repeated herein. The radius of curvature in this embodiment is the radius of curvature of each lens at the optical axis, and the reference wavelength of the refractive index and the abbe number is 587.6 nm.

TABLE 2a

Table 2b shows high-order coefficient coefficients A4, A6, A8, a10, a12, a14, a16, a18, and a20 that can be used for the respective aspherical mirror surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12 in the second embodiment, wherein the respective aspherical surface types can be defined by the formulas given in the first embodiment.

TABLE 2b

Number of noodles

S1

S2

S3

S4

S5

S6

K

-3.9747E-01

-5.4692E+01

-5.9935E+01

-3.1144E+01

-5.2209E+01

6.4952E+01

A4

6.9598E-02

-8.2351E-03

-3.0540E-02

1.6047E-01

2.4062E-02

-2.2943E-01

A6

-2.3992E-01

-4.6102E-01

-8.6874E-02

-3.5339E-02

-8.0875E-01

-3.1349E-01

A8

3.9961E+00

8.3480E+00

5.7996E+00

6.2882E-01

-6.3747E+00

-1.7370E+00

A10

-3.0146E+01

-7.8147E+01

-6.2276E+01

-2.6346E+00

8.7220E+01

1.3286E+01

A12

1.4167E+02

4.3759E+02

3.7730E+02

9.3760E+00

-5.6977E+02

-5.6405E+01

A14

-4.0840E+02

-1.4763E+03

-1.3699E+03

-7.2933E+00

2.1806E+03

1.7388E+02

A16

6.9951E+02

2.9086E+03

2.9152E+03

-7.1885E+01

-4.9290E+03

-3.3680E+02

A18

-6.4025E+02

-3.0235E+03

-3.3109E+03

2.4284E+02

6.0857E+03

3.5750E+02

A20

2.3710E+02

1.2429E+03

1.5186E+03

-2.1616E+02

-3.1295E+03

-1.5377E+02

Number of noodles

S7

S8

S9

S10

S11

S12

K

-2.3905E+01

-3.1638E+01

1.8631E+01

9.0338E+01

-1.2277E+01

-3.8966E+00

A4

-3.5052E-01

-1.7087E-01

2.9524E-02

-4.4992E-01

-5.9207E-01

-4.5510E-01

A6

2.9863E-01

1.0016E+00

7.7294E-01

2.1301E+00

5.1828E-01

6.2747E-01

A8

3.3227E-02

-5.1922E+00

-4.0154E+00

-5.6038E+00

3.3518E-01

-6.0420E-01

A10

-1.0141E+01

1.1843E+01

6.2215E+00

8.6352E+00

-1.6654E+00

3.8926E-01

A12

7.1922E+01

-4.4353E+00

-4.2474E-01

-8.5749E+00

2.0757E+00

-1.7047E-01

A14

-1.9571E+02

-2.2179E+01

-1.1091E+01

5.6891E+00

-1.3227E+00

5.0093E-02

A16

2.6398E+02

3.7342E+01

1.5849E+01

-2.4618E+00

4.6908E-01

-9.4230E-03

A18

-1.7831E+02

-2.3742E+01

-9.8188E+00

6.2616E-01

-8.8120E-02

1.0192E-03

A20

4.8215E+01

5.5774E+00

2.4030E+00

-7.0174E-02

6.8502E-03

-4.7886E-05

Fig. 4 shows a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the second embodiment. The longitudinal spherical aberration curve represents the deviation of convergence focuses of light rays with different wavelengths after passing through each lens of the optical system, and the reference wavelengths of the longitudinal spherical aberration curve are 656.2725nm, 587.5618nm, 546.0740nm, 486.1327nm and 435.8343 nm; the astigmatism curves represent meridional image surface curvature and sagittal image surface curvature, wherein S represents sagittal direction, T represents meridional direction, and the reference wavelength of the astigmatism curves is 546.0740 nm; the distortion curve represents the distortion magnitude values corresponding to different angles of view, and the reference wavelength of the distortion curve is 546.0740 nm. As can be seen from fig. 4, the optical system according to the second embodiment can achieve good imaging quality.

EXAMPLE III

As shown in fig. 5, a straight line 11 indicates an optical axis, a side of the first lens L1 away from the second lens L2 is an object side 12, and a side of the sixth lens L6 away from the fifth lens L5 is an image side 13. In the optical system provided in this embodiment, the stop STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the infrared filter IRCF are arranged in order from the object side 12 to the image side 13.

The third lens element L3 with positive refractive power has a concave object-side surface S5 at a paraxial region and a convex image-side surface S6 at a paraxial region, and is made of plastic material.

It should be noted that the lens material is not limited to a Plastic material, and in some embodiments, the material of at least one lens in the optical system is Plastic (PC), and the Plastic material may be polycarbonate, gum, or the like. In some embodiments, at least one lens of the optical system is made of Glass (GL). The lens made of plastic can reduce the production cost of the optical system, and the lens made of glass can endure higher or lower temperature and has excellent optical effect and better stability. In some embodiments, lenses of different materials may be disposed in the optical system, that is, a design combining a glass lens and a plastic lens may be adopted, but the specific configuration relationship may be determined according to practical requirements, and is not exhaustive here.

Table 3a shows a table of characteristics of the optical system of the present embodiment, and definitions of various parameters can be obtained from the description of the previous embodiments, which are not repeated herein. The radius of curvature in this example is the radius of curvature of each lens at the optical axis, and the reference wavelength of the refractive index and the abbe number is 587.6 nm.

TABLE 3a

Table 3b shows high-order coefficient A4, A6, A8, a10, a12, a14, a16, a18, and a20, which are high-order coefficient coefficients that can be used for each aspherical mirror surface S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12 in the third embodiment, wherein each aspherical surface type can be defined by the formula given in the first embodiment.

TABLE 3b

Fig. 6 shows a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the third embodiment. The longitudinal spherical aberration curve represents the deviation of convergence focuses of light rays with different wavelengths after passing through each lens of the optical system, and the reference wavelengths of the longitudinal spherical aberration curve are 656.2725nm, 587.5618nm, 546.0740nm, 486.1327nm and 435.8343 nm; the astigmatism curves represent meridional image surface curvature and sagittal image surface curvature, wherein S represents sagittal direction, T represents meridional direction, and the reference wavelength of the astigmatism curves is 546.0740 nm; the distortion curve represents the distortion magnitude values corresponding to different angles of view, and the reference wavelength of the distortion curve is 546.0740 nm. As can be seen from fig. 6, the optical system according to the third embodiment can achieve good image quality.

Example four

As shown in fig. 7, a straight line 11 indicates an optical axis, a side of the first lens L1 away from the second lens L2 is an object side 12, and a side of the sixth lens L6 away from the fifth lens L5 is an image side 13. In the optical system provided in this embodiment, the stop STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the infrared filter IRCF are arranged in order from the object side 12 to the image side 13.

The third lens element L3 with positive refractive power has a convex object-side surface S5 at a paraxial region and a concave image-side surface S6 at a paraxial region, and is made of plastic material.

The fourth lens element L4 with positive refractive power is made of plastic, and has a concave object-side surface S7 at a paraxial region and a convex image-side surface S8 at a paraxial region.

The sixth lens element L6 with negative refractive power is made of plastic, and has an object-side surface S11 being convex at a paraxial region and an image-side surface S12 being concave at a paraxial region.

The infrared filter IRCF is arranged behind the sixth lens L6 and comprises an object side surface S13 and an image side surface S14, the infrared filter IRCF is used for filtering infrared light, the light entering the image plane is visible light, the wavelength of the visible light is 380nm-780nm, and the infrared filter IRCF is made of glass.

Table 4a shows a table of characteristics of the optical system of the present embodiment, and the definitions of the parameters can be obtained from the description of the previous embodiments, which are not repeated herein. The radius of curvature in this embodiment is the radius of curvature of each lens at the optical axis, and the reference wavelength of the refractive index and the abbe number is 587.6 nm.

TABLE 4a

Table 4b shows high-order coefficient coefficients A4, A6, A8, a10, a12, a14, a16, a18, and a20 that can be used for the respective aspherical mirror surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12 in the fourth embodiment, wherein the respective aspherical surface types can be defined by the formulas given in the first embodiment.

TABLE 4b

Fig. 8 shows a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the fourth embodiment. The longitudinal spherical aberration curve represents the deviation of convergence focuses of light rays with different wavelengths after passing through each lens of the optical system, and the reference wavelengths of the longitudinal spherical aberration curve are 656.2725nm, 587.5618nm, 546.0740nm, 486.1327nm and 435.8343 nm; the astigmatism curves represent meridional image surface curvature and sagittal image surface curvature, wherein S represents sagittal direction, T represents meridional direction, and the reference wavelength of the astigmatism curves is 546.0740 nm; the distortion curve represents the distortion magnitude values corresponding to different angles of view, and the reference wavelength of the distortion curve is 546.0740 nm. As can be seen from fig. 8, the optical system according to the fourth embodiment can achieve good image quality.

EXAMPLE five

As shown in fig. 9, a straight line 11 indicates an optical axis, a side of the first lens L1 away from the second lens L2 is an object side 12, and a side of the sixth lens L6 away from the fifth lens L5 is an image side 13. In the optical system provided in this embodiment, the stop STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, and the infrared filter IRCF are arranged in order from the object side 12 to the image side 13.

The fifth lens element L5 with negative refractive power is made of plastic material, and has a concave object-side surface S9 and a concave image-side surface S10 at a paraxial region, both of which are aspheric.

The sixth lens element L6 with positive refractive power is made of plastic, and has an object-side surface S11 being convex at a paraxial region and an image-side surface S12 being concave at a paraxial region.

Note that the lens material is not limited to a Plastic material, and in some embodiments, the material of at least one lens in the optical system is Plastic (PC), and the Plastic material may be polycarbonate, gum, or the like. In some embodiments, at least one lens of the optical system is made of Glass (GL). The lens made of plastic can reduce the production cost of the optical system, and the lens made of glass can endure higher or lower temperature and has excellent optical effect and better stability. In some embodiments, lenses of different materials may be disposed in the optical system, that is, a design combining a glass lens and a plastic lens may be adopted, but the specific configuration relationship may be determined according to actual requirements, which is not exhaustive here.

Table 5a shows a characteristic table of the optical system of the present embodiment, and definitions of parameters in the characteristic table can be obtained from the description of the foregoing embodiments, which are not repeated herein. The radius of curvature in this embodiment is the radius of curvature of each lens at the optical axis, and the reference wavelength of the refractive index and the abbe number is 587.6 nm.

TABLE 5a

Table 5b shows high-order term coefficients A4, A6, A8, a10, a12, a14, a16, a18, and a20 that may be used for each aspherical mirror surface S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12 in the fifth embodiment, wherein each aspherical surface type may be defined by the formula given in the first embodiment.

TABLE 5b

Fig. 10 shows a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the fifth embodiment. The longitudinal spherical aberration curve represents the deviation of convergence focuses of light rays with different wavelengths after passing through each lens of the optical system, and the reference wavelengths of the longitudinal spherical aberration curve are 656.2725nm, 587.5618nm, 546.0740nm, 486.1327nm and 435.8343 nm; the astigmatism curves represent meridional image surface curvature and sagittal image surface curvature, wherein S represents sagittal direction, T represents meridional direction, and the reference wavelength of the astigmatism curves is 546.0740 nm; the distortion curve represents the distortion magnitude values corresponding to different angles of view, and the reference wavelength of the distortion curve is 546.0740 nm. As can be seen from fig. 10, the optical system according to the fifth embodiment can achieve good image quality.

It should be noted that six lenses are exemplified in the five embodiments of the present application, but the plurality of lenses in the optical system provided by the present application includes, but is not limited to, the first lens to the sixth lens, and the number of lenses in the optical system may be changed to obtain the effects described in the specification of the present application without departing from the technical solution claimed by the present application. Illustratively, the optical system of the present application may further include a seventh lens, an eighth lens, and the like.

Table 6 shows values of tan (hfov)/SD11, f12/f, f2/R21, | (R51+ R52)/(R51-R52) |, CT6/| SAG61|, FFL/f, TTL/ctal, TTL/Imgh of the optical systems of the first to fifth embodiments.

TABLE 6

	tan(HFOV)/SD11(mm ^-1 )	f12/f	f2/R21	\|(R51+R52)/(R51-R52)\|
					First embodiment	1.449	1.541	0.606	2.126
Second embodiment	1.237	1.424	0.484	1.999
					Third embodiment	1.415	1.410	1.842	1.401
Fourth embodiment	1.418	1.379	2.773	1.442
					Fifth embodiment	1.396	1.368	2.858	0.883
	CT6/\|SAG61\|	FFL/f	TTL/ctal	TTL/Imgh
					First embodiment	0.884	0.191	2.166	1.255
Second embodiment	1.180	0.207	1.955	1.402
					Third embodiment	1.045	0.182	2.167	1.292
Fourth embodiment	0.952	0.218	2.147	1.292
					Fifth embodiment	2.037	0.263	2.136	1.325

As can be seen from table 6, each example satisfies: 1.2mm ^-1 <tan(HFOV)/SD11<1.5mm ^-1 ，1.3<f12/f<1.6，0.4<f2/R21<3，0.8<|(R51+R52)/(R51-R52)|<2.2，0.8<CT6/|SAG61|<2.1，0.15<FFL/f<0.3，1.9<TTL/ctal<2.2，1.25<TTL/Imgh<1.41。

Referring to fig. 11, the optical system according to the present application is applied to a camera module 20 in an electronic device 30. The electronic device 30 may be a mobile phone, a tablet computer, an unmanned aerial vehicle, a computer, or the like. The image sensor of the camera module 20 is located on the image side of the optical system, and the camera module 20 is assembled inside the electronic device 30.

The present application provides a camera module 20, which includes a photosensitive element and the optical system provided in the embodiment of the present application, wherein the photosensitive element is located on the image side of the optical system and is used for converting light rays passing through the first lens to the sixth lens and entering the electronic photosensitive element into electrical signals of an image. The electron sensor may be a Complementary Metal Oxide Semiconductor (CMOS) or a Charge-coupled Device (CCD). By installing the optical system in the camera module 20, the camera module 20 has the characteristics of miniaturization, lightness and thinness and has good imaging quality.

The application further provides an electronic device 30, the electronic device 30 includes a fixing member and the camera module 20 provided in the embodiment of the application, and the camera module 20 is disposed on the fixing member. The fixing member may be a motor, such as a voice coil motor, and may also be other fixing devices. This electronic equipment 30 can be cell-phone, panel computer, unmanned aerial vehicle, computer etc.. By installing the camera module 20 in the electronic device 30, the electronic device 30 is advantageous to have the characteristics of miniaturization, lightness and thinness and good imaging quality.

While the foregoing is directed to the preferred embodiment of the present application, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention.

Claims

1. An optical system comprising a plurality of lenses including a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens arranged in this order from an object side to an image side:

the first lens element with positive refractive power has a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region;

the second lens element with negative refractive power has a concave object-side surface and a concave image-side surface at paraxial region;

the third lens element with positive refractive power;

the fourth lens element with refractive power has a concave object-side surface at a paraxial region thereof and a convex image-side surface at a paraxial region thereof;

the fifth lens element with negative refractive power has a concave object-side surface at a paraxial region;

the sixth lens element with refractive power has a convex object-side surface at a paraxial region thereof and a concave image-side surface at a paraxial region thereof;

the optical system satisfies the following conditional expression:

1.2mm ^-1 <tan(HFOV)/SD11<1.5mm ^-1 ，

tan (hfov) is a tangent value of half of a maximum angle of view of the optical system, and SD11 is half of a maximum effective aperture of an object-side surface of the first lens.

2. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

1.3<f12/f<1.6，

f12 is the combined focal length of the first and second lenses, and f is the effective focal length of the optical system.

3. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

0.4<f2/R21<3，

f2 is the focal length of the second lens, R21 is the radius of curvature of the object-side surface of the second lens at the optical axis.

4. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

0.8<|(R51+R52)/(R51-R52)|<2.2，

r51 is a radius of curvature of an object-side surface of the fifth lens at an optical axis, and R52 is a radius of curvature of an image-side surface of the fifth lens at the optical axis.

5. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

0.8<CT6/|SAG61|<2.1，

CT6 is the thickness of the sixth lens on the optical axis, SAG61 is the sagittal height of the object-side surface of the sixth lens at the maximum effective half aperture.

6. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

0.15<FFL/f<0.3，

FFL is the shortest distance from the image side surface of the sixth lens element to the imaging surface in the optical axis direction, and f is the effective focal length of the optical system.

7. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

1.9<TTL/ctal<2.2，

TTL is a distance on the optical axis from the object-side surface of the first lens element to the image plane, and ctal is a sum of thicknesses on the optical axis of the first lens element to the sixth lens element.

8. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

1.25<TTL/Imgh<1.41，

TTL is a distance on the optical axis from the object-side surface of the first lens element to the image plane, and Imgh is half the image height corresponding to the maximum field angle of the optical system.

9. A camera module comprising a photosensitive element and the optical system of any one of claims 1 to 8, wherein the photosensitive element is located on the image side of the optical system.

10. An electronic device, comprising a fixing member and the camera module according to claim 9, wherein the camera module is disposed on the fixing member.