CN113156612B

CN113156612B - Optical system, image capturing module and electronic equipment

Info

Publication number: CN113156612B
Application number: CN202110354705.3A
Authority: CN
Inventors: 曾晗; 刘秀; 李明
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2021-03-31
Filing date: 2021-03-31
Publication date: 2022-06-24
Anticipated expiration: 2041-03-31
Also published as: CN113156612A

Abstract

The invention relates to an optical system, an image capturing module and an electronic device. The optical system comprises a first lens element with positive refractive power having a convex object-side surface at paraxial region; a second lens element with negative refractive power having a concave object-side surface at paraxial region; a third lens element with positive refractive power; a fourth lens element with refractive power; a fifth lens element with refractive power having a concave object-side surface at paraxial region; and a sixth lens element with negative refractive power having a convex object-side surface and a concave image-side surface; and satisfies the following conditions: CT1/TTL is more than or equal to 0.2 and less than or equal to 0.25; CT1 is the thickness of the first lens element on the optical axis, and TTL is the distance from the object-side surface of the first lens element to the image plane of the optical system on the optical axis. The optical system can realize small head design, and further meets the design requirement of high screen ratio.

Description

Optical system, image capturing module and electronic equipment

Technical Field

The present invention relates to the field of camera shooting, and in particular, to an optical system, an image capturing module and an electronic device.

Background

With the development of the camera technology, more and more electronic devices place the camera lens under the display screen to realize the design of the camera function under the screen. Meanwhile, as the market demand for high-screen-ratio electronic devices is increasing, the industry is also constantly working on the design of high-screen-ratio electronic devices. For an electronic device with an off-screen camera function, the size of the camera lens affects the size of an opening of a display screen, and further affects the screen ratio of the electronic device. However, the size of the optical system at present is difficult to meet the design requirement of high screen ratio of the electronic equipment.

Disclosure of Invention

Accordingly, there is a need for an optical system, an image capturing module and an electronic device to achieve a small head design and further meet the design requirement of high screen ratio of the electronic device.

An optical system includes, in order from an object side to an image side along an optical axis:

a first lens element with positive refractive power having a convex object-side surface at paraxial region;

a second lens element with negative refractive power having a concave object-side surface at paraxial region;

a third lens element with positive refractive power;

a fourth lens element with refractive power;

a fifth lens element with refractive power having a concave object-side surface at paraxial region; and

a sixth lens element with negative refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region;

and the optical system satisfies the following conditional expression:

0.2≤CT1/TTL≤0.25；

wherein CT1 is a thickness of the first lens element on an optical axis, i.e., a center thickness of the first lens element, and TTL is a distance from an object-side surface of the first lens element to an image plane of the optical system on the optical axis, i.e., an optical total length of the optical system.

In the optical system, the first lens element has positive refractive power, which is beneficial to shortening the total length of the optical system, thereby being beneficial to the miniaturization design of the optical system. The object-side surface of the first lens element is convex at a paraxial region thereof, which is advantageous for enhancing the positive refractive power of the first lens element, thereby further shortening the total length of the optical system. The second lens element with negative refractive power can correct the aberration generated by the first lens element. The third lens element with positive refractive power can satisfactorily correct aberrations occurring in the first and second lens elements. The object-side surface of the fifth lens element is concave at paraxial region, which is advantageous for correcting aberration of the optical system. The sixth lens element with negative refractive power is advantageous for correcting aberrations of the optical system, and can ensure that the back focus of the optical system has sufficient assembly space. The object side surface of the sixth lens element is convex at the paraxial region, which is beneficial to correcting distortion and high-order aberration of the peripheral field of view, thereby improving the resolving power of the optical system. The image side surface of the sixth lens element is concave at the paraxial region, which is advantageous for keeping the principal point of the optical system away from the image plane, thereby being advantageous for shortening the total length of the optical system.

Satisfying the conditional expression is beneficial to increasing the central thickness of the first lens, so that the mechanical bearing position of the first lens is beneficial to moving towards the image side to deepen the embedding depth of the optical system, and further beneficial to reducing the opening size of the display screen of the electronic equipment to improve the screen occupation ratio of the electronic equipment; meanwhile, the radial size of the first lens is reduced, so that the size of the head of the optical system is reduced, the small head design of the optical system is realized, and the design requirement of high screen occupation ratio of electronic equipment is met.

In one embodiment, the optical system satisfies the following relationship:

0.25≤SD11/IMGH≤0.35；

wherein SD11 is the maximum effective half aperture of the object-side surface of the first lens, and IMGH is half the image height corresponding to the maximum field angle of the optical system. Satisfy above-mentioned conditional expression, the ratio of the maximum effective aperture of the object side of first lens and the optical system half image height of rational configuration is favorable to dwindling the radial dimension of first lens to realize optical system's little head design, with the trompil size of reducing the electronic equipment display screen, and then promote electronic equipment's screen and account for the ratio.

In one embodiment, the optical system satisfies the following relationship:

0.5≤CT6/|SAG61|≤1.2；

wherein CT6 is the thickness of the sixth lens on the optical axis, SAG61 is the sagittal height of the object side of the sixth lens at the maximum effective aperture. The shape of the sixth lens can be reasonably designed by satisfying the conditional expression, so that the manufacturing and molding of the sixth lens are facilitated, and the defect of poor molding is reduced; meanwhile, the sixth lens is favorable for correcting the field curvature generated by each lens of the object space and balancing the field curvature of different view fields of the optical system, so that the light imaging image quality of different view fields is uniform, and the imaging quality of the optical system is improved. If the lower limit of the conditional expression is lower, the object-side surface of the sixth lens is excessively curved in the circumferential direction, which tends to cause molding defects and lower the molding yield of the sixth lens. Exceeding the upper limit of the above conditional expression, the surface shape of the object-side surface of the sixth lens at the circumference is too gentle, which results in insufficient deflection capability of the sixth lens for the off-axis field rays and is not favorable for correction of aberrations such as optical system distortion and field curvature.

In one embodiment, the optical system satisfies the following relationship:

0.6≤f2/R21≤1.1；

wherein f2 is an effective focal length of the second lens, and R21 is a radius of curvature of an object-side surface of the second lens at an optical axis. The refractive power and the object side surface shape of the second lens can be reasonably configured when the conditional expression is satisfied, and the second lens is favorable for balancing the positive spherical aberration generated by the first lens, so that the imaging quality of the optical system is improved; in addition, the second lens is favorable for diverging the light rays, so that the field angle of the optical system is favorably enlarged. Below the lower limit of the conditional expression, the negative refractive power provided by the second lens element is insufficient, which is not favorable for correcting the spherical aberration of the optical system; and the image side surface of the second lens is excessively bent, so that the tolerance sensitivity of the second lens is increased, and the molding of the second lens is not facilitated. When the optical system is in a state of being in a non-optical state, the optical system is in a non-optical state, and the optical system is in a non-optical state; in addition, it is also easy to cause excessive correction of aberration generated by the second lens with respect to the first lens, thereby degrading the imaging quality of the optical system.

In one embodiment, the optical system satisfies the following relationship:

0.2≤|(R51+R52)/(R51-R52)|≤7；

wherein R51 is a radius of curvature of an object-side surface of the fifth lens element at an optical axis, and R52 is a radius of curvature of an image-side surface of the fifth lens element at the optical axis. The curvature radii of the object-side surface and the image-side surface of the fifth lens element at the optical axis can be reasonably configured to satisfy the conditional expressions, so that the shape of the fifth lens element is not excessively bent, the tolerance sensitivity of the fifth lens element can be reduced while the fifth lens element corrects the astigmatism of the optical system, and the molding yield of the fifth lens element is improved.

In one embodiment, the optical system further includes an infrared filter disposed on the image side of the sixth lens element, and the optical system satisfies the following relation:

0.5≤FFL/ET62≤1.6；

wherein FFL is a shortest distance between an image side surface of the sixth lens element and an image plane of the optical system in the optical axis direction, and ET62 is a distance between a maximum effective aperture of the image side surface of the sixth lens element and an object side surface of the infrared filter in the optical axis direction. Satisfying the above conditional expression, is beneficial to reducing the deflection angle of the light, thereby being beneficial to better converging the light on the imaging surface, correcting the aberration of the optical system and improving the resolving power of the optical system; meanwhile, the matching degree of the optical system and the photosensitive element is improved, so that the imaging quality of the optical system is improved. If the optical aberration is lower than the lower limit of the conditional expression or exceeds the upper limit of the conditional expression, the light deflection angle is easily too large, so that the light convergence effect is poor, the aberration of the optical system is not corrected, and the imaging quality of the optical system is further reduced.

In one embodiment, the optical system satisfies the following relationship:

1.5≤TTL/ETAL≤2；

wherein ETAL is a sum of distances in an optical axis direction from a maximum effective aperture of an object-side surface of each lens element to a maximum effective aperture of an image-side surface of the lens element, that is, a sum of thicknesses of edges of the first lens element, the second lens element, the third lens element, the fourth lens element, the fifth lens element and the sixth lens element, wherein a thickness of an edge of the first lens element is a distance in the optical axis direction from the maximum effective aperture of the object-side surface of the first lens element to the maximum effective aperture of the image-side surface of the first lens element. The condition formula is satisfied, the requirement of high imaging quality is satisfied, and simultaneously, the total length of the optical system is favorably shortened, so that the lens arrangement of the optical system is more compact, and the miniaturization design of the optical system is realized.

In one embodiment, the optical system satisfies the following relationship:

1.5≤IMGH/SD61≤1.8；

wherein IMGH is half of an image height corresponding to a maximum field angle of the optical system, and SD61 is a maximum effective half aperture of an object-side surface of the sixth lens element. Satisfying above-mentioned conditional expression, being favorable to increasing optical system's imaging surface to be favorable to matcing bigger size's photosensitive element, with the formation of image quality that promotes optical system, therefore can make optical system possess good formation of image quality when realizing little head design. Being lower than the lower limit of the conditional expression, the optical system is not easy to match with a large-size photosensitive element, which is not beneficial to the improvement of the imaging quality of the optical system. When the angle exceeds the upper limit of the conditional expression, the incidence angle of the chief ray corresponding to the maximum field of view is too large, so that a dark angle is easy to appear, and the imaging quality is influenced.

In one embodiment, the optical system satisfies the following relationship:

5.5mm≤TTL/tan(HFOV)≤7mm；

wherein the HFOV is half of a maximum field angle of the optical system. Satisfying the above conditional expressions, the total optical length and the maximum angle of view of the optical system can be reasonably arranged, and the miniaturization design of the optical system can be realized while satisfying good imaging quality. When the angle of view of the optical system is too large, ghost images and serious distortion easily appear in the edge field of view, which is not favorable for improving the imaging quality. Exceeding the upper limit of the above conditional expressions makes the optical system too long in total optical length, which is not favorable for realizing a compact design.

An image capturing module includes a photosensitive element and the optical system of any of the above embodiments, wherein the photosensitive element is disposed at an image side of the optical system. The optical system is adopted in the image capturing module, so that the small head design of the image capturing module can be realized.

An electronic device comprises a shell and the image capturing module, wherein the image capturing module is arranged on the shell. Adopt above-mentioned getting for instance the module in the electronic equipment, optical system can realize little head design to be favorable to reducing electronic equipment's display screen trompil size, and then promote electronic equipment's screen and account for than.

Drawings

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

FIG. 2 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a first embodiment of the present application;

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

FIG. 4 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a second embodiment of the present application;

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

FIG. 6 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a third embodiment of the present application;

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

FIG. 8 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a fourth embodiment of the present application;

FIG. 9 is a schematic view of an optical system according to a fifth embodiment of the present application;

FIG. 10 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a fifth embodiment of the present application;

FIG. 11 is a schematic view of an image capturing module according to an embodiment of the present application;

fig. 12 is a schematic diagram of an electronic device in an embodiment of the present application.

Detailed Description

In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

In the description of the present invention, it is to be understood that the terms "central," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," "circumferential," and the like are used in the orientations and positional relationships indicated in the drawings for convenience in describing the invention and to simplify the description, and are not intended to indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are not to be considered limiting of the invention.

Furthermore, the terms "first", "second" and "first" are used for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one such feature. In the description of the present invention, "a plurality" means at least two, e.g., two, three, etc., unless explicitly specified otherwise.

In the present invention, unless otherwise expressly stated or limited, the terms "mounted," "connected," "secured," and the like are to be construed broadly and can, for example, be fixedly connected, detachably connected, or integrally formed; can be mechanically or electrically connected; they may be directly connected or indirectly connected through intervening media, or they may be connected internally or in any other suitable relationship, unless expressly stated otherwise. The specific meanings of the above terms in the present invention can be understood according to specific situations by those of ordinary skill in the art.

In the present invention, unless otherwise expressly stated or limited, the first feature "on" or "under" the second feature may be directly contacting the first and second features or indirectly contacting the first and second features through an intermediate. Also, a first feature "on," "over," and "above" a second feature may be directly or diagonally above the second feature, or may simply indicate that the first feature is at a higher level than the second feature. A first feature being "under," "below," and "beneath" a second feature may be directly under or obliquely under the first feature, or may simply mean that the first feature is at a lesser elevation than the second feature.

It will be understood that when an element is referred to as being "secured to" or "disposed on" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and the like as used herein are for illustrative purposes only and do not denote a unique embodiment.

Referring to fig. 1, in some embodiments of the present application, an optical system 100 includes, in order from an object side to an image side along an optical axis 110, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, and a sixth lens L6. Specifically, the first lens L1 includes an object-side surface S1 and an image-side surface S2, the second lens L2 includes an object-side surface S3 and an image-side surface S4, the third lens L3 includes an object-side surface S5 and an image-side surface S6, the fourth lens L4 includes an object-side surface S7 and an image-side surface S8, the fifth lens L5 includes an object-side surface S9 and an image-side surface S10, and the sixth lens L6 includes an object-side surface S11 and an image-side surface S12.

The first lens element L1 with positive refractive power is advantageous for shortening the total system length of the optical system 100, and therefore, the optical system 100 can be miniaturized. The object-side surface S1 of the first lens element L1 is convex in a direction close to the optical axis 110, which is favorable for enhancing the positive refractive power of the first lens element L1, and thus is favorable for further shortening the total length of the optical system 100. The second lens element L2 has negative refractive power, which is favorable for correcting the aberration generated by the first lens element L1. The object-side surface S3 of the second lens element L2 is concave at the paraxial region 110. The third lens element L3 has positive refractive power, and can correct aberrations generated in the first lens element L1 and the second lens element L2 well. The fourth lens element L4 has refractive power, and the fifth lens element L5 has refractive power. The object-side surface S9 of the fifth lens element L5 is concave at the paraxial region 110, which is advantageous for correcting the aberration of the optical system 100. The sixth lens element L6 with negative refractive power is advantageous for correcting the image side of the optical system 100, and can ensure sufficient space for assembling the back focus of the optical system 100. The object-side surface S11 of the sixth lens element L6 is convex at the paraxial region 110, which is favorable for correcting the peripheral field distortion and the high-order aberrations, thereby improving the resolution of the optical system 100. The image-side surface S12 of the sixth lens element L6 is concave at the paraxial region 110, which is advantageous for moving the principal point of the optical system 100 away from the image plane, thereby shortening the overall length of the optical system 100.

In addition, in some embodiments, the optical system 100 is provided with a stop STO, which may be disposed on the object side of the first lens L1 or on the object side surface S1 of the first lens L1. In some embodiments, the optical system 100 further includes an infrared filter L7 disposed on the image side of the sixth lens L6, and the infrared filter L7 includes an object-side surface S13 and an image-side surface S14. Furthermore, the optical system 100 further includes an image plane S15 located on the image side of the sixth lens L6, the image plane S15 is an imaging plane of the optical system 100, and incident light is adjusted by the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, and the sixth lens L6 and can be imaged on the image plane S15. It should be noted that the infrared filter L7 may be an infrared cut filter, and is used for filtering the interference light and preventing the interference light from reaching the image plane S15 of the optical system 100 to affect the normal imaging.

In some embodiments, the object-side surface and the image-side surface of each lens of optical system 100 are both aspheric. The adoption of the aspheric surface structure can improve the flexibility of lens design, effectively correct spherical aberration and improve imaging quality. In other embodiments, the object-side surface and the image-side surface of each lens of the optical system 100 may be spherical. It should be noted that the above embodiments are only examples of some embodiments of the present application, and in some embodiments, the surface of each lens in the optical system 100 may be an aspheric surface or any combination of spherical surfaces.

In some embodiments, each lens in the optical system 100 may be made of glass or plastic. The lens made of plastic material can reduce the weight and production cost of the optical system 100, and the small size of the optical system is matched to realize the light and thin design of the optical system. The glass lens provides the optical system 100 with excellent optical performance and high temperature resistance. It should be noted that the material of each lens in the optical system 100 may be any combination of glass and plastic, and is not necessarily both glass and plastic.

It is to be noted that the first lens L1 does not mean that there is only one lens, and in some embodiments, there may be two or more lenses in the first lens L1, and the two or more lenses can form a cemented lens, and a surface of the cemented lens closest to the object side can be regarded as the object side surface S1, and a surface of the cemented lens closest to the image side can be regarded as the image side surface S2. Alternatively, although no cemented lens is formed between the lenses of the first lens L1, the distance between the lenses is relatively fixed, and in this case, the object-side surface of the lens closest to the object side is the object-side surface S1, and the image-side surface of the lens closest to the image side is the image-side surface S2. In addition, the number of lenses in the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5 or the sixth lens L6 in some embodiments may also be greater than or equal to two, and a cemented lens may be formed between any two adjacent lenses, and may also be a non-cemented lens.

Further, in some embodiments, the optical system 100 satisfies the conditional expression: CT1/TTL is more than or equal to 0.2 and less than or equal to 0.25; the CT1 is a thickness of the first lens element L1 on the optical axis 110, and the TTL is a distance from the object-side surface S1 of the first lens element L1 to the image plane of the optical system 100 on the optical axis 110, i.e., an optical total length of the optical system 100. Specifically, CT1/TTL can be: 0.206, 0.211, 0.213, 0.219, 0.225, 0.228, 0.230, 0.234, 0.237 or 0.244. Satisfying the above conditional expression is beneficial to increasing the central thickness of the first lens L1, so as to facilitate moving the mechanical bearing position of the first lens L1 toward the image side, to deepen the embedded depth of the optical system 100, and to further facilitate reducing the size of the opening of the display screen of the electronic device, so as to increase the screen occupation ratio of the electronic device; meanwhile, the radial size of the first lens L1 is reduced, so that the size of the head of the optical system 100 is reduced, the small head design of the optical system 100 is realized, and the design requirement of high screen occupation ratio of the electronic device is met.

In some embodiments, the optical system 100 satisfies the conditional expression: SD11/IMGH is more than or equal to 0.25 and less than or equal to 0.35; SD11 is the maximum effective half aperture of the object-side surface S1 of the first lens L1, and IMGH is half the image height corresponding to the maximum field angle of the optical system 100. Specifically, SD11/IMGH may be: 0.268, 0.271, 0.275, 0.279, 0.283, 0.286, 0.291, 0.294, 0.297 or 0.305. Satisfy above-mentioned conditional expression, the ratio of the maximum effective aperture of the object side S1 and the optical system 100 half image height of the first lens L1 of rational configuration is favorable to dwindling the radial size of first lens L1 to realize optical system 100 'S little head design, with the trompil size of reducing the electronic equipment display screen, and then promote electronic equipment' S screen to account for than.

It should be noted that in some embodiments, the optical system 100 may match a photosensitive element having a rectangular photosensitive surface, and the imaging surface of the optical system 100 coincides with the photosensitive surface of the photosensitive element. At this time, the effective pixel area on the imaging plane of the optical system 100 has a horizontal direction and a diagonal direction, the maximum field angle of the optical system 100 can be understood as the maximum field angle of the optical system 100 in the diagonal direction, and ImgH can be understood as a half of the length of the effective pixel area on the imaging plane of the optical system 100 in the diagonal direction.

In some embodiments, the optical system 100 satisfies the conditional expression: CT 6/SAG 61 is more than or equal to 0.5 and less than or equal to 1.2; where CT6 is the thickness of the sixth lens L6 on the optical axis 110, and SAG61 is the rise of the object-side surface S11 of the sixth lens L6 at the maximum effective aperture, that is, the distance from the intersection point of the object-side surface S11 of the sixth lens L6 and the optical axis 110 to the maximum effective aperture of the object-side surface S11 of the sixth lens L6 in the direction of the optical axis 110, where in the direction parallel to the optical axis, the maximum effective aperture of the object-side surface S11 of the sixth lens L6 is located at the intersection point of the object-side surface S11 of the second lens L2 and the optical axis 110, SAG61 is a positive value, and in the direction parallel to the optical axis, the maximum effective aperture of the object-side surface S11 of the sixth lens L6 is located at the object-side of the intersection point S11 of the second lens L2 and the optical axis 110, and SAG61 is a negative value. . Specifically, CT6/| SAG61| may be: 0.771, 0.782, 0.799, 0.801, 0.897, 0.982, 0.993, 1.002, 1.053 or 1.093. The shape of the sixth lens L6 can be reasonably designed by satisfying the conditional expressions, so that the manufacturing and molding of the sixth lens L6 are facilitated, and the defect of poor molding is reduced; meanwhile, the sixth lens L6 is also favorable for correcting the field curvature generated by each lens of the object space and balancing the field curvatures of the optical system 100 in different fields, so that the light imaging image quality of different fields is favorable for being uniform, and the imaging quality of the optical system 100 is improved. Below the lower limit of the conditional expression, the object-side surface S11 of the sixth lens L6 is excessively curved in the circumferential direction, which tends to cause molding defects and reduce the molding yield of the sixth lens L6. Exceeding the upper limit of the above conditional expression, the surface shape of the object-side surface S11 of the sixth lens L6 at the circumference is too gentle, and the sixth lens L6 has insufficient deflecting ability for the off-axis field rays, which is not favorable for correcting aberrations such as distortion and field curvature of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: f2/R21 is more than or equal to 0.6 and less than or equal to 1.1; where f2 is the effective focal length of the second lens L2, and R21 is the radius of curvature of the object-side surface S3 of the second lens L2 at the optical axis 110. Specifically, f2/R21 may be: 0.719, 0.786, 0.824, 0.935, 1.133, 1.256, 1.336, 1.502, 1.635 or 1.752. The refractive power of the second lens element L2 and the shape of the object-side surface S3 can be reasonably configured to satisfy the above conditional expressions, which is beneficial for the second lens element L2 to balance the positive spherical aberration generated by the first lens element L1, thereby improving the imaging quality of the optical system 100; in addition, the second lens L2 is also favorable for diverging the light, thereby being favorable for enlarging the field angle of the optical system 100. Below the lower limit of the above conditional expression, the negative refractive power provided by the second lens element L2 is insufficient, which is not favorable for correcting the spherical aberration of the optical system 100; and the image side surface S4 of the second lens L2 is too curved, so that the tolerance sensitivity of the second lens L2 is increased, and the molding of the second lens L2 is not facilitated. Above the upper limit of the above conditional expression, the negative refractive power of the second lens element L2 is too strong, and the light is excessively diffused, which is not favorable for shortening the total length of the optical system 100; in addition, it is also easy to cause excessive correction of aberration generated in the first lens L1 by the second lens L2, thereby degrading the imaging quality of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: less than or equal to 0.2 (R51+ R52)/(R51-R52) less than or equal to 7; wherein R51 is the radius of curvature of the object-side surface S9 of the fifth lens element L5 on the optical axis 110, and R52 is the radius of curvature of the image-side surface S10 of the fifth lens element L5 on the optical axis 110. Specifically, | (R51+ R52)/(R51-R52) | may be: 0.323, 0.638, 0.992, 1.647, 1.741, 2.035, 2.968, 3.751, 4.691, or 6.835. Satisfying the above conditional expressions, the curvature radii of the object-side surface S1 and the image-side surface S2 of the fifth lens element L5 on the optical axis 110 can be reasonably arranged, so that the shape of the fifth lens element L5 is not excessively curved, the tolerance sensitivity of the fifth lens element L5 can be reduced while the fifth lens element L5 corrects the astigmatism of the optical system 100, and the molding yield of the fifth lens element L5 can be improved.

In some embodiments, the optical system 100 satisfies the conditional expression: FFL/ET62 is more than or equal to 0.5 and less than or equal to 1.6; wherein, FFL is the shortest distance between the image-side surface S12 of the sixth lens element L6 and the image-forming surface of the optical system 100 in the direction of the optical axis 110, and ET62 is the distance between the maximum effective aperture of the image-side surface S12 of the sixth lens element L6 and the object-side surface S13 of the infrared filter L7 in the direction of the optical axis 110. Specifically, FFL/ET62 may be: 0.749, 0.801, 0.856, 0.993, 1.025, 1.136, 1.264, 1.338, 1.448 or 1.569. Satisfying the above conditional expression is beneficial to reducing the deflection angle of the light, so as to be beneficial to better converging the light on the imaging surface, so as to correct the aberration of the optical system 100 and improve the resolving power of the optical system 100; meanwhile, the matching degree of the optical system 100 and the photosensitive element is also improved, so that the imaging quality of the optical system 100 is improved. If the value is lower than the lower limit of the conditional expression or exceeds the upper limit of the conditional expression, the light deflection angle is easily too large, which results in poor light convergence effect, which is not favorable for correcting aberration of the optical system 100, and further reduces the imaging quality of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: TTL/ETAL is more than or equal to 1.5 and less than or equal to 2; where ETAL is the sum of distances in the direction of the optical axis 110 from the maximum effective aperture on the object-side surface to the maximum effective aperture on the image-side surface of each lens in the optical system 100. Specifically, TTL/ETAL may be: 1.712, 1.725, 1.764, 1.798, 1.805, 1.863, 1.889, 1.925, 1.952 or 1.961. Satisfying the above conditional expressions, while satisfying the requirement of high imaging quality, it is also beneficial to shorten the total length of the optical system 100, so that the lens arrangement of the optical system 100 is more compact, so as to realize the miniaturization design of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: IMGH/SD61 is more than or equal to 1.5 and less than or equal to 1.8; IMGH is half the image height corresponding to the maximum field angle of the optical system 100, and SD61 is the maximum effective half diameter of the object-side surface S11 of the sixth lens L6. Specifically, IMGH/SD61 may be: 1.595, 1.622, 1.645, 1.673, 1.693, 1.705, 1.725, 1.749, 1.763, or 1.779. Satisfying the above conditional expressions is favorable to increasing the imaging surface of the optical system 100, thereby being favorable to matching the photosensitive element with larger size, and improving the imaging quality of the optical system 100, and thus the optical system 100 can have good imaging quality while realizing the design of the small head. Below the lower limit of the above conditional expression, the optical system 100 is not easily matched with a large-sized photosensitive element, which is not favorable for improving the imaging quality of the optical system 100. When the angle exceeds the upper limit of the conditional expression, the incidence angle of the chief ray corresponding to the maximum field of view is too large, so that a dark angle is easy to appear, and the imaging quality is influenced.

In some embodiments, the optical system 100 satisfies the conditional expression: TTL/tan (HFOV) is less than or equal to 5.5mm and less than or equal to 7 mm; the HFOV is half of the maximum field angle of the optical system 100. Specifically, TTL/tan (hfov) may be: 6.083, 6.112, 6.195, 6.254, 6.374, 6.458, 6.734, 6.789, 6.882 or 6.954, the numerical units being mm. Satisfying the above conditional expressions, the optical total length and the maximum angle of view of the optical system 100 can be arranged reasonably, and the optical system 100 can be designed in a compact size while satisfying good imaging quality. Below the lower limit of the conditional expression, the field angle of the optical system 100 is too large, which causes the phenomenon of ghost image and serious distortion in the edge field, and is not favorable for improving the imaging quality. Exceeding the upper limit of the above conditional expression makes the optical system 100 too long in total optical length, which is disadvantageous for realizing a compact design.

The reference wavelengths for the above effective focal length values are all 546.0740 nm.

Based on the above description of the embodiments, more specific embodiments and drawings are set forth below for detailed description.

First embodiment

Referring to fig. 1 and fig. 2, fig. 1 is a schematic structural diagram of an optical system 100 in the first embodiment, and the optical system 100 includes, in order from an object side to an image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with negative refractive power, a fifth lens element L5 with positive refractive power, and a sixth lens element L6 with negative refractive power. Fig. 2 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the first embodiment, sequentially from left to right, wherein the reference wavelength of the astigmatism graph and the distortion graph is 546.0740nm, and the other embodiments are the same.

The object-side surface S1 of the first lens element L1 is convex at the paraxial region 110, and the image-side surface S2 is concave at the paraxial region 110;

the object-side surface S3 of the second lens element L2 is concave at the paraxial region 110, and the image-side surface S4 is concave at the paraxial region 110;

the object-side surface S5 of the third lens element L3 is convex at the paraxial region 110, and the image-side surface S6 is convex at the paraxial region 110;

the object-side surface S7 of the fourth lens element L4 is concave at the paraxial region 110, and the image-side surface S8 is convex at the paraxial region 110;

the object-side surface S9 of the fifth lens element L5 is concave at the paraxial region 110, and the image-side surface S10 is convex at the paraxial region 110;

the object-side surface S11 of the sixth lens element L6 is convex at the paraxial region 110, and the image-side surface S12 is concave at the paraxial region 110.

The object-side surface and the image-side surface of the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, and the sixth lens L6 are aspheric.

It should be noted that, in the present application, when a surface of the lens is described as being convex at a position near the optical axis 110 (the central region of the surface), it is understood that the region of the surface of the lens near the optical axis 110 is convex. When a surface of a lens is described as being concave at the circumference, it is understood that the surface is concave in the region near the maximum effective radius. For example, when the surface is convex at a paraxial region 110 and also convex at a peripheral region, the shape of the surface from the center (the intersection of the surface with the optical axis 110) to the edge direction may be purely convex; or a convex shape at the center is firstly transited to a concave shape, and then becomes a convex shape near the maximum effective radius. Here, only examples are made to illustrate the relationship at the optical axis 110 and the circumference, and various shape structures (concave-convex relationship) of the surface are not fully embodied, but other cases can be derived from the above examples.

The first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5 and the sixth lens L6 are all made of plastic.

Further, the optical system 100 satisfies the conditional expression: CT1/TTL is 0.211; the CT1 is a thickness of the first lens element L1 on the optical axis 110, and the TTL is a distance from the object-side surface S1 of the first lens element L1 to the image plane of the optical system 100 on the optical axis 110, i.e., an optical total length of the optical system 100. Satisfying the above conditional expression is beneficial to increasing the central thickness of the first lens L1, so as to facilitate moving the mechanical bearing position of the first lens L1 toward the image side, to deepen the embedded depth of the optical system 100, and to further facilitate reducing the size of the opening of the display screen of the electronic device, so as to increase the screen occupation ratio of the electronic device; meanwhile, the radial size of the first lens L1 is reduced, so that the size of the head of the optical system 100 is reduced, the small head design of the optical system 100 is realized, and the design requirement of high screen occupation ratio of the electronic device is met.

The optical system 100 satisfies the conditional expression: SD11/IMGH is 0.268; SD11 is the maximum effective half aperture of the object-side surface S1 of the first lens L1, and IMGH is half the image height corresponding to the maximum field angle of the optical system 100. Satisfy above-mentioned conditional expression, the ratio of the maximum effective aperture of the object side S1 that can rationally dispose first lens L1 and optical system 100 half image height is favorable to dwindling first lens L1 ' S radial dimension to realize optical system 100 ' S little head design, with the trompil size of reducing the electronic equipment display screen, and then promote electronic equipment ' S screen to account for than.

The optical system 100 satisfies the conditional expression: CT6/| SAG61| ═ 0.771; wherein CT6 is the thickness of the sixth lens L6 on the optical axis 110, and SAG61 is the rise of the object-side surface S11 of the sixth lens L6 at the maximum effective aperture, that is, the distance from the intersection point of the object-side surface S11 of the sixth lens L6 and the optical axis 110 to the maximum effective aperture of the object-side surface S11 of the sixth lens L6 in the direction of the optical axis 110. The shape of the sixth lens L6 can be reasonably designed by satisfying the conditional expressions, so that the manufacturing and molding of the sixth lens L6 are facilitated, and the defect of poor molding is reduced; meanwhile, the sixth lens L6 is also favorable for correcting the field curvature generated by each lens of the object space and balancing the field curvatures of the optical system 100 in different fields, so that the light imaging image quality of different fields is favorable for being uniform, and the imaging quality of the optical system 100 is improved. Below the lower limit of the conditional expression, the object-side surface S11 of the sixth lens L6 is excessively curved in the circumferential direction, which tends to cause molding defects and reduce the molding yield of the sixth lens L6. Exceeding the upper limit of the above conditional expression, the surface shape of the object-side surface S11 of the sixth lens L6 at the circumference is too gentle, and the sixth lens L6 has insufficient deflecting ability for the off-axis field rays, which is not favorable for correcting aberrations such as distortion and field curvature of the optical system 100.

The optical system 100 satisfies the conditional expression: f2/R21 is 0.812; where f2 is the effective focal length of the second lens L2, and R21 is the radius of curvature of the object-side surface S3 of the second lens L2 at the optical axis 110. The refractive power of the second lens element L2 and the shape of the object-side surface S3 can be reasonably configured to satisfy the above conditional expressions, which is beneficial for the second lens element L2 to balance the positive spherical aberration generated by the first lens element L1, thereby improving the imaging quality of the optical system 100; in addition, the second lens L2 is also favorable for diverging the light, thereby being favorable for enlarging the field angle of the optical system 100. Below the lower limit of the above conditional expression, the negative refractive power provided by the second lens element L2 is insufficient, which is not favorable for correcting the spherical aberration of the optical system 100; and the image side surface S4 of the second lens L2 is too curved, so that the tolerance sensitivity of the second lens L2 is increased, and the molding of the second lens L2 is not facilitated. Above the upper limit of the above conditional expression, the negative refractive power of the second lens element L2 is too strong, and the light is excessively diffused, which is not favorable for shortening the total length of the optical system 100; in addition, it is also easy to cause excessive correction of aberration generated in the first lens L1 by the second lens L2, thereby degrading the imaging quality of the optical system 100.

The optical system 100 satisfies the conditional expression: (R51+ R52)/(R51-R52) | 4.534; wherein R51 is the radius of curvature of the object-side surface S9 of the fifth lens element L5 on the optical axis 110, and R52 is the radius of curvature of the image-side surface S10 of the fifth lens element L5 on the optical axis 110. Satisfying the above conditional expressions, the curvature radii of the object-side surface S1 and the image-side surface S2 of the fifth lens element L5 on the optical axis 110 can be reasonably arranged, so that the shape of the fifth lens element L5 is not excessively curved, the tolerance sensitivity of the fifth lens element L5 can be reduced while the fifth lens element L5 corrects the astigmatism of the optical system 100, and the molding yield of the fifth lens element L5 can be improved.

The optical system 100 satisfies the conditional expression: FFL/ET62 ═ 1.115; wherein, FFL is the shortest distance between the image-side surface S12 of the sixth lens element L6 and the image-forming surface of the optical system 100 in the direction of the optical axis 110, and ET62 is the distance between the maximum effective aperture of the image-side surface S12 of the sixth lens element L6 and the object-side surface S13 of the infrared filter L7 in the direction of the optical axis 110. Satisfying the above conditional expressions is beneficial to reducing the deflection angle of the light, thereby being beneficial to better converging the light on the imaging surface, being beneficial to correcting the aberration of the optical system 100 and improving the resolving power of the optical system 100; meanwhile, the matching degree of the optical system 100 and the photosensitive element is also improved, so that the imaging quality of the optical system 100 is improved. If the value is lower than the lower limit of the conditional expression or exceeds the upper limit of the conditional expression, the light deflection angle is easily too large, which results in poor light convergence effect, which is not favorable for correcting aberration of the optical system 100, and further reduces the imaging quality of the optical system 100.

The optical system 100 satisfies the conditional expression: TTL/ETAL 1.939; where ETAL is the sum of distances in the direction of the optical axis 110 from the maximum effective aperture on the object-side surface to the maximum effective aperture on the image-side surface of each lens in the optical system 100. Satisfying the above conditional expressions, while satisfying the requirement of high imaging quality, it is also beneficial to shorten the total length of the optical system 100, so that the lens arrangement of the optical system 100 is more compact, so as to realize the miniaturization design of the optical system 100.

The optical system 100 satisfies the conditional expression: IMGH/SD61 ═ 1.691; IMGH is half the image height corresponding to the maximum field angle of the optical system 100, and SD61 is the maximum effective half diameter of the object-side surface S11 of the sixth lens L6. Satisfying the above conditional expressions is favorable to increasing the imaging surface of the optical system 100, thereby being favorable to matching the photosensitive element with larger size, and improving the imaging quality of the optical system 100, and thus the optical system 100 can have good imaging quality while realizing the design of the small head. Below the lower limit of the above conditional expression, the optical system 100 is not easily matched with a large-sized photosensitive element, which is not favorable for improving the imaging quality of the optical system 100. When the angle exceeds the upper limit of the conditional expression, the incidence angle of the chief ray corresponding to the maximum field of view is too large, so that a dark angle is easy to appear, and the imaging quality is influenced.

The optical system 100 satisfies the conditional expression: TTL/tan (hfov) ═ 6.781 mm; the HFOV is half of the maximum field angle of the optical system 100. Satisfying the above conditional expressions, the optical total length and the maximum angle of view of the optical system 100 can be arranged reasonably, and the optical system 100 can be designed in a compact size while satisfying good imaging quality.

In addition, the parameters of the optical system 100 are given in table 1. Among them, the image plane S15 in table 1 may be understood as an imaging plane of the optical system 100. The elements from the object plane (not shown) to the image plane S15 are sequentially arranged in the order of the elements from top to bottom in table 1. The Y radius in table 1 is the radius of curvature of the object-side or image-side surface of the corresponding surface number at the optical axis 110. Surface numbers S1 and S2 denote an object-side surface S1 and an image-side surface S2 of the first lens L1, respectively, that is, in the same lens, a surface with a smaller surface number is an object-side surface, and a surface with a larger surface number is an image-side surface. The first numerical value in the "thickness" parameter column of the first lens element L1 is the thickness of the lens element along the optical axis 110, and the second numerical value is the distance between the image-side surface and the rear surface of the lens element along the image-side direction along the optical axis 110.

Note that, in this embodiment and the following embodiments, the optical system 100 may not be provided with the infrared filter L7, but the distance from the image-side surface S12 of the sixth lens L6 to the image surface S15 is kept constant.

In the first embodiment, the effective focal length f of the optical system 100 is 4.5224mm, the f-number FNO is 2.6, half of the maximum field angle HFOV is 35.0122 °, and the total optical length TTL is 4.75 mm. In the first and following embodiments, it is understood that the total optical length TTL of the optical system 100 is 4.85mm or less, and the optical system 100 can be designed to be compact.

The reference wavelength of the focal length of each lens was 546.0740nm, and the reference wavelengths of the refractive index and the abbe number were 587.56nm (d-line), which is the same for the other examples.

TABLE 1

Further, aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are given by table 2. The surface numbers S1-S12 represent the image side or the object side S1-S12, respectively. And K-a20 from top to bottom respectively represent types of aspheric coefficients, where K represents a conic coefficient, a4 represents a quartic aspheric coefficient, a6 represents a sextic aspheric coefficient, A8 represents an octal aspheric coefficient, and so on. In addition, the aspherical surface coefficient formula is as follows:

where Z is the distance from the corresponding point on the aspheric surface to the plane tangent to the surface vertex, r is the distance from the corresponding point on the aspheric surface to the optical axis 110, c is the curvature of the aspheric surface vertex, k is the conic coefficient, and Ai is the coefficient corresponding to the i-th high order term in the aspheric surface profile formula.

TABLE 2

In addition, fig. 2 includes a Longitudinal Spherical Aberration diagram (Longitudinal Spherical Aberration) of the optical system 100, which shows the deviation of the converging focal points of the light rays of different wavelengths after passing through the lens. The ordinate of the longitudinal spherical aberration diagram represents Normalized Pupil coordinates (Normalized Pupil Coordinator) from the Pupil center to the Pupil edge, and the abscissa represents the distance (in mm) from the imaging plane to the intersection of the ray with the optical axis 110. It can be known from the longitudinal spherical aberration diagram that the convergent focus deviation degrees of the light rays with different wavelengths in the first embodiment tend to be consistent, and the diffuse speckle or the chromatic halo in the imaging picture is effectively suppressed. FIG. 2 also includes a field curvature diagram (ASTIGMATIC FIELD CURVES) of optical system 100, where the S curve represents sagittal field curvature at 546.0740nm and the T curve represents meridional field curvature at 546.0740 nm. As can be seen from the figure, the curvature of field of the optical system 100 is small, the curvature of field and astigmatism of each field are well corrected, and the center and the edge of the field have clear images. Fig. 2 also includes a DISTORTION map (distorsion) of the optical system 100, and it can be seen that the image DISTORTION caused by the main beam is small and the imaging quality of the system is excellent.

Second embodiment

Referring to fig. 3 and 4, fig. 3 is a schematic structural diagram of the optical system 100 in the second embodiment, in which the optical system 100 includes, in order from an object side to an image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with negative refractive power, and a sixth lens element L6 with negative refractive power. Fig. 4 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the second embodiment, which is shown from left to right.

The object-side surface S1 of the first lens element L1 is convex at the paraxial region 110, and the image-side surface S2 is convex at the paraxial region 110;

the object-side surface S5 of the third lens element L3 is convex at the paraxial region 110, and the image-side surface S6 is concave at the paraxial region 110;

the object-side surface S7 of the fourth lens element L4 is convex at the paraxial region 110, and the image-side surface S8 is convex at the paraxial region 110;

the object-side surface S9 of the fifth lens element L5 is concave at the paraxial region 110, and the image-side surface S10 is concave at the paraxial region 110;

In addition, the parameters of the optical system 100 are given in table 3, and the definitions of the parameters can be obtained from the first embodiment, which is not described herein.

TABLE 3

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 4, and the definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

TABLE 4

And, according to the above provided parameter information, the following data can be derived:

in addition, as can be seen from the aberration diagram in fig. 4, the longitudinal spherical aberration, curvature of field, and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Third embodiment

Referring to fig. 5 and 6, fig. 5 is a schematic structural diagram of the optical system 100 in the third embodiment, in which the optical system 100 includes, in order from an object side to an image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with negative refractive power, and a sixth lens element L6 with negative refractive power. Fig. 6 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the third embodiment, from left to right.

the object-side surface S7 of the fourth lens element L4 is convex at the paraxial region 110, and the image-side surface S8 is concave at the paraxial region 110;

In addition, the parameters of the optical system 100 are given in table 5, and the definitions of the parameters can be obtained from the first embodiment, which is not described herein again.

TABLE 5

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 6, and the definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

TABLE 6

in addition, as can be seen from the aberration diagram in fig. 6, the longitudinal spherical aberration, curvature of field, and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Fourth embodiment

Referring to fig. 7 and 8, fig. 7 is a schematic structural diagram of the optical system 100 in the fourth embodiment, in which the optical system 100 includes, in order from an object side to an image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with negative refractive power, a fifth lens element L5 with negative refractive power, and a sixth lens element L6 with negative refractive power. Fig. 8 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the fourth embodiment, which is shown from left to right.

the object-side surface S3 of the second lens element L2 is concave at the paraxial region 110, and the image-side surface S4 is convex at the paraxial region 110;

the object-side surface S5 of the third lens element L3 is concave at the paraxial region 110, and the image-side surface S6 is convex at the paraxial region 110;

In addition, the parameters of the optical system 100 are given in table 7, and the definitions of the parameters can be obtained from the first embodiment, which is not described herein.

TABLE 7

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 8, and the definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

TABLE 8

And, according to the above provided parameter information, the following data can be deduced:

in addition, as can be seen from the aberration diagram in fig. 8, the longitudinal spherical aberration, curvature of field, and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Fifth embodiment

Referring to fig. 9 and 10, fig. 9 is a schematic structural diagram of the optical system 100 in the fifth embodiment, in which the optical system 100 includes, in order from an object side to an image side, a stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with positive refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with negative refractive power, and a sixth lens element L6 with negative refractive power. Fig. 10 is a graph showing the longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the fifth embodiment from left to right.

In addition, the parameters of the optical system 100 are given in table 9, and the definitions of the parameters can be obtained from the first embodiment, which is not described herein.

TABLE 9

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are shown in table 10, and the definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

Watch 10

in addition, as can be seen from the aberration diagram in fig. 10, the longitudinal spherical aberration, curvature of field, and distortion of the optical system 100 are well controlled, so that the optical system 100 of this embodiment has good imaging quality.

Referring to fig. 11, in some embodiments, the optical system 100 may be assembled with the photosensitive element 210 to form the image capturing module 200. At this time, the light-sensing surface of the light-sensing element 210 may be regarded as the image surface S15 of the optical system 100. The image capturing module 200 may further include an infrared filter L7, and the infrared filter L7 is disposed between the image side surface S12 and the image surface S15 of the sixth lens element L6. Specifically, the photosensitive element 210 may be a Charge Coupled Device (CCD) or a Complementary Metal-Oxide Semiconductor (CMOS) Device. The optical system 100 is adopted in the image capturing module 200, so that the small head design of the image capturing module 200 can be realized.

Referring to fig. 11 and 12, in some embodiments, the image capturing module 200 may be applied to an electronic device 300, the electronic device includes a housing 310, and the image capturing module 200 is disposed in the housing 310. Specifically, the electronic apparatus 300 may be, but is not limited to, a wearable device such as a mobile phone, a video phone, a smart phone, an electronic book reader, a vehicle-mounted image capturing apparatus such as a car recorder, or a smart watch. When the electronic device 300 is a smartphone, the housing 310 may be a middle frame of the electronic device 300.

Further, in some embodiments, the electronic device 300 includes a display screen 320, the image capturing module 200 is disposed below the display screen 320, and the display screen 320 is perforated to enable the image capturing module 200 to receive light. It can be understood that, by adopting the image capturing module 200 in the electronic device 300, the optical system 100 can realize a small head design, thereby being beneficial to reducing the size of the opening of the display screen of the electronic device 300 and further improving the screen occupation ratio of the electronic device 300.

The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent should be subject to the appended claims.

Claims

1. An optical system, wherein six lenses having refractive power are provided, the optical system sequentially includes from an object side to an image side along an optical axis:

a third lens element with positive refractive power;

a fourth lens element with refractive power;

and the optical system satisfies the following conditional expression:

0.2≤CT1/TTL≤0.25；

0.25≤SD11/IMGH≤0.35；

wherein CT1 is a thickness of the first lens element on an optical axis, TTL is a distance from an object-side surface of the first lens element to an image plane of the optical system on the optical axis, SD11 is a maximum effective half aperture of the object-side surface of the first lens element, and IMGH is a half of an image height corresponding to a maximum field angle of the optical system.

2. The optical system of claim 1, further comprising an optical stop disposed on an object side of the first lens, or on an object side of the first lens.

3. The optical system according to claim 1, wherein the following conditional expression is satisfied:

0.5≤CT6/|SAG61|≤1.2；

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

4. The optical system according to claim 1, wherein the following conditional expression is satisfied:

0.6≤f2/R21≤1.1；

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

5. The optical system according to claim 1, wherein the following conditional expression is satisfied:

0.2≤|(R51+R52)/(R51-R52)|≤7；

wherein R51 is a radius of curvature of an object-side surface of the fifth lens element at an optical axis, and R52 is a radius of curvature of an image-side surface of the fifth lens element at the optical axis.

6. The optical system according to claim 1, further comprising an infrared filter disposed on an image side of the sixth lens, wherein the optical system satisfies the following conditional expression:

0.5≤FFL/ET62≤1.6；

wherein FFL is a shortest distance between an image side surface of the sixth lens element and an image plane of the optical system in the optical axis direction, and ET62 is a distance between a maximum effective aperture of the image side surface of the sixth lens element and an object side surface of the infrared filter in the optical axis direction.

7. The optical system according to claim 1, wherein the following conditional expression is satisfied:

1.5≤TTL/ETAL≤2；

wherein ETAL is a sum of distances in an optical axis direction from a maximum effective aperture on an object side surface to a maximum effective aperture on an image side surface of each lens in the optical system.

8. The optical system according to claim 1, wherein the following conditional expression is satisfied:

1.5≤IMGH/SD61≤1.8；

wherein IMGH is half of an image height corresponding to a maximum field angle of the optical system, and SD61 is a maximum effective half aperture of an object-side surface of the sixth lens element.

9. The optical system according to claim 1, wherein the following conditional expression is satisfied:

5.5mm≤TTL/tan(HFOV)≤7mm；

wherein the HFOV is half of a maximum field angle of the optical system.

10. An image capturing module, comprising a photosensitive element and the optical system of any one of claims 1 to 9, wherein the photosensitive element is disposed on an image side of the optical system.

11. An electronic device, comprising a housing and the image capturing module of claim 10, wherein the image capturing module is disposed on the housing.