CN112612117A

CN112612117A - Optical system, image capturing module and electronic equipment

Info

Publication number: CN112612117A
Application number: CN202011641605.0A
Authority: CN
Inventors: 谢晗; 刘彬彬; 李明
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2020-12-31
Filing date: 2020-12-31
Publication date: 2021-04-06

Abstract

The invention relates to an optical system, an image capturing module and an electronic device. An optical system comprising, in order from an object side to an image side: a first lens element with negative refractive power having a concave object-side surface at paraxial region; a second lens element with positive refractive power having a convex object-side surface at paraxial region; a third lens element with refractive power having a convex object-side surface at a paraxial region and a concave image-side surface at a paraxial region; a fourth lens element with positive refractive power; a fifth lens element with refractive power; a sixth lens element with positive refractive power; a seventh lens element with negative refractive power; and the optical system satisfies the following conditional expression: i SAG1/f 1I 100 is less than or equal to 2; wherein SAG1 is the rise in sagittal height at the maximum effective clear aperture of the object side of the first lens, and f1 is the effective focal length of the first lens. The optical system has small total length and is beneficial to realizing miniaturization design.

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

Along with the rapid development in the field of camera shooting, optical systems are more and more widely applied to electronic equipment such as smart phones, tablet computers and wearable equipment, so that the electronic equipment has a shooting function, and the diversification function of the electronic equipment is improved. Meanwhile, with the rapid development of electronic devices, the market has higher and higher requirements for the image pickup function, the image pickup lens with high pixels is gradually popular, and the size of the carried photosensitive element is larger and larger. However, the conventional optical system generally increases the imaging resolution by increasing the number of lenses, which increases the total length of the optical system, restricts the reduction of the thickness of the electronic device, and is difficult to meet the requirement of miniaturization design of the electronic device.

Disclosure of Invention

Accordingly, there is a need for an optical system, an image capturing module and an electronic device to shorten the total length of the optical system.

An optical system comprising, in order from an object side to an image side:

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

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

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

a fourth lens element with positive refractive power;

a fifth lens element with refractive power;

a sixth lens element with positive refractive power;

a seventh lens element with negative refractive power;

and the optical system satisfies the following conditional expression:

|SAG1/f1|*100≤2；

SAG1 is the rise of the first lens at the maximum effective clear aperture of the object side surface, namely the distance from the intersection point of the object side surface of the first lens and the optical axis to the maximum effective clear aperture of the object side surface of the first lens in the optical axis direction, and f1 is the effective focal length of the first lens.

In the optical system, the second lens element provides positive refractive power for the optical system, and the object-side surface of the second lens element is convex at a paraxial region, which is beneficial to improving the light converging capability of the second lens element and further beneficial to shortening the total length of the optical system. When the above conditional expressions are satisfied, the object side surface of the first lens tends to be gentle, so that the size of the first lens in the optical axis direction is favorably shortened, the total length of the optical system is further shortened, and the miniaturization design of the optical system is realized. Meanwhile, the surface of the object side surface of the first lens is gentle and small in curvature, and the injection molding of the first lens is facilitated. When the upper limit of the above conditional expression is exceeded, the rise of the object-side surface of the first lens is too large, and the surface shape is too curved, resulting in an excessively large dimension of the first lens in the optical axis direction, and further causing the first lens to occupy an excessively large space, which hinders the reduction of the total length of the optical system, and is disadvantageous for the miniaturization design of the optical system.

In one embodiment, the optical system satisfies the following conditional expression:

TTL/ImgH≤1.7；

wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an image plane of the optical system, that is, a total optical length of the optical system, and ImgH is a half of an image height corresponding to a maximum field angle of the optical system. When the conditional expressions are satisfied, the ratio of the total optical length and the half-image height of the optical system can be reasonably configured, so that the total system length of the optical system is effectively compressed, and the miniaturization design of the optical system is facilitated. In addition, the ImgH determines the size of the imaging size of the optical system, and when the conditional expression is satisfied, the system can be matched with a large-size photosensitive element, so that large-image-plane and high-pixel shooting can be realized. When the upper limit of the above conditional expression is exceeded, the total length of the optical system is too long, which is disadvantageous to the miniaturization design of the optical system, making it difficult for the optical system to match with an ultra-thin electronic device.

1.7≤FNO/tan(HFOV)≤2.0；

wherein FNO is an f-number of the optical system, and HFOV is a half of a maximum field angle of the optical system. When the conditional expressions are met, the diaphragm number and the field angle of the optical system can be reasonably configured, so that the optical system has a large diaphragm, the aberration of the optical system can be corrected, and the imaging quality of the optical system can be improved. When the upper limit of the above conditional expression is exceeded, the f-number of the optical system is too large, the light-entering amount is reduced, and the imaging quality of the optical system in a weak light environment is easily reduced. When the optical system is lower than the lower limit of the conditional expression, the diaphragm number of the optical system is too small, so that the effective light-passing aperture of the diaphragm is too large, the marginal rays of the field of view are difficult to be effectively adjusted, and the aberration of the optical system is not favorably corrected.

90≤V3+V4+V5≤110；

wherein V3 is the abbe number of the third lens under d-line, V4 is the abbe number of the fourth lens under d-line, and V5 is the abbe number of the fifth lens under d-line, i.e., V3, V4, and V5 are the abbe numbers of the third lens, the fourth lens, and the fifth lens at a reference wavelength of 587.56nm, respectively. When the above conditional expressions are satisfied, abbe numbers of the third lens, the fourth lens and the fifth lens can be reasonably configured, so that chromatic aberration of the optical system is effectively corrected, and imaging quality of the optical system is improved. When the abbe number of the third lens, the fourth lens and the fifth lens is less than the lower limit of the conditional expression, the third lens, the fourth lens and the fifth lens are insufficient in correcting chromatic aberration, and the imaging quality of the optical system is reduced. If the upper limit of the above conditional expression is exceeded, the abbe numbers of the third lens, the fourth lens, and the fifth lens are too large, which increases the cost of the optical system.

1.8≤f2/R3≤2.0；

wherein f2 is an effective focal length of the second lens, and R3 is a radius of curvature of an object-side surface of the second lens at an optical axis. When the above conditional expressions are satisfied, the second lens element provides sufficient positive refractive power for the optical system, which is beneficial to shortening the total length of the optical system, and meanwhile, the refractive power of the second lens element is not too strong, which is beneficial to correcting the spherical aberration of the optical system. When the effective focal length of the second lens element exceeds the upper limit of the conditional expression, the effective focal length of the second lens element is too long, and the positive refractive power of the second lens element is too weak, which is not favorable for shortening the total length of the optical system. When the refractive power is lower than the lower limit of the conditional expression, the positive refractive power of the second lens is too strong, which makes the spherical aberration of the optical system difficult to correct, and is not favorable for improving the imaging quality of the optical system.

2.5≤CT2/CT1≤3.5；

wherein CT2 is the thickness of the second lens element on the optical axis, i.e. the center thickness of the second lens element, and CT1 is the thickness of the first lens element on the optical axis, i.e. the center thickness of the first lens element. When the above conditional expressions are satisfied, the thickness of the first lens on the optical axis is small, the surface shape is gentle, the space occupation ratio of the first lens in the optical system is favorably reduced, and the miniaturization design of the optical system is further favorably realized. If the upper limit of the above conditional expression is exceeded, the size of the second lens on the optical axis becomes too large, which is disadvantageous for the compact design of the optical system. Below the lower limit of the above conditional expression, the size of the first lens on the optical axis is too large, resulting in an increase in the total system length of the optical system, which is disadvantageous for the miniaturized design of the optical system.

-10≤(R7+R8)/(R7-R8)≤1.5；

wherein R7 is a radius of curvature of an object-side surface of the fourth lens element at an optical axis, and R8 is a radius of curvature of an image-side surface of the fourth lens element at the optical axis. The fourth lens is located in the middle of the optical system, when the condition is met, the surface type bending degree of the object side surface and the surface type bending degree of the image side surface of the fourth lens can be reasonably increased, the fourth lens is favorable for being matched with other lenses of the optical system to image, the aberration of the optical system is favorable for being corrected, and the imaging quality of the optical system is improved.

Y1/Y2≤1.5；

y1 is half of the maximum effective clear aperture of the object side surface of the first lens, and Y2 is half of the maximum effective clear aperture of the object side surface of the second lens. When the condition is satisfied, the difference between the maximum effective light-passing apertures of the object side surface of the first lens and the object side surface of the second lens can be reduced, so that the deflection angle of light entering the optical system is not too large, and the generation of aberration is favorably reduced. When the difference between the maximum effective light-passing apertures of the object-side surface of the first lens and the object-side surface of the second lens is too large, the tolerance sensitivity of the first lens and the second lens is easily increased, and the molding yield of the first lens and the second lens is reduced.

-0.65≤R12/f6≤-0.45；

wherein R12 is a radius of curvature of an image-side surface of the sixth lens at an optical axis, and f6 is an effective focal length of the sixth lens. The sixth lens element provides positive refractive power to the optical system, and when the above conditional expressions are satisfied, an image-side surface of the sixth lens element at a paraxial region is a convex surface, which is favorable for the sixth lens element and the seventh lens element to cooperate with each other, so as to shorten a back focal length of the optical system and effectively correct distortion of the optical system.

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 total length of the optical system is favorably reduced, and the miniaturization design of the image capturing module is favorably realized.

An electronic device comprises a shell and the image capturing module, wherein the image capturing module is arranged on the shell. The image capturing module is adopted in the electronic equipment, so that the miniaturization design of the electronic equipment is facilitated.

Drawings

FIG. 1 is a schematic view of an optical system in a first embodiment of the present application;

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

FIG. 3 is a schematic view of an optical system in a second embodiment of the present application;

FIG. 4 is a 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 view of an optical system according to a third embodiment of the present application;

FIG. 6 is a 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 view of an optical system according to a fourth embodiment of the present application;

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

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

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

FIG. 11 is a schematic view of an optical system in a sixth embodiment of the present application;

FIG. 12 is a spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a sixth embodiment of the present application;

fig. 13 is a schematic view of an image capturing module according to an embodiment of the present application;

fig. 14 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 specifically limited 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 by those skilled in the art according to specific situations.

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.

In some embodiments of the present disclosure, referring to fig. 1, the optical system 100 includes, in order from an object side to an image side, 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 a seventh lens L7. 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, the sixth lens L6 includes an object-side surface S11 and an image-side surface S12, and the seventh lens L7 includes an object-side surface S13 and an image-side surface S14.

The first lens element L1 with negative refractive power has a concave object-side surface S1 at a paraxial region 110 of the first lens element L1. The second lens element L2 with positive refractive power has a convex object-side surface S3 of the second lens element L2 near the optical axis 110, which is favorable for improving the light converging capability of the second lens element L2, and further is favorable for shortening the total system length of the optical system 100. 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 fourth lens element L4 with positive refractive power, the fifth lens element L5 with positive refractive power, the sixth lens element L6 with positive refractive power and the seventh lens element L7 with negative refractive power.

In addition, in some embodiments, the optical system 100 is provided with a stop (not shown), the stop may be disposed at the object side of the first lens L1, further, the stop may be disposed before the object side surface S1 or on the object side surface S1 of the first lens L1, or the stop may be disposed at the image side of the seventh lens L7, further, the stop may be disposed after the image side surface S14 or on the image side surface S14 of the seventh lens L7, or the stop may be disposed between any two lenses of the first lens L1 to the seventh lens L7, specifically, in some embodiments, the stop may be disposed between the second lens L2 and the third lens L3, for example, at the image side surface of the second lens L2.

In some embodiments, the optical system 100 further includes an infrared filter L8 disposed at an image side of the seventh lens L7, and the infrared filter L8 includes an object-side surface S15 and an image-side surface S16. Furthermore, the optical system 100 further includes an image plane S17 located on the image side of the seventh lens L7, the image plane S17 is an imaging plane of the optical system 100, and incident light can be adjusted by 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 seventh lens L7 and then imaged on the image plane S17. It should be noted that the infrared filter L8 may be an infrared cut filter, and is used for filtering the interference light and preventing the interference light from reaching the image plane S17 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 aspherical structure can improve the flexibility of lens design, effectively correct the spherical aberration of the optical system 100 and improve the 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 of the optical system 100 and the production cost, and the small size of the optical system is matched to realize the light and small 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, the sixth lens L6 or the seventh lens L7 in some embodiments may be greater than or equal to two, and a cemented lens may be formed between any two adjacent lenses, or a non-cemented lens may be used.

Further, in some embodiments, the optical system 100 satisfies the conditional expression: i SAG1/f 1I 100 is less than or equal to 2; where SAG1 is the rise at the maximum effective clear aperture of the object-side surface S1 of the first lens L1, and f1 is the effective focal length of the first lens L1. Specifically, | SAG1/f1 |. 100 may be: 0.5, 0.6, 0.7, 0.8, 0.9, 1.0, 1.1 or 1.2. When the above conditional expressions are satisfied, the object-side surface S1 of the first lens L1 tends to be gentle, which is favorable for shortening the dimension of the first lens L1 in the optical axis 110 direction, and further shortening the total system length of the optical system 100, thereby realizing the miniaturization design of the optical system 100. Meanwhile, the object side surface S1 of the first lens L1 is flat and gentle in surface shape and small in curvature, and injection molding of the first lens L1 is facilitated. If the upper limit of the above conditional expression is exceeded, the rise of the object-side surface S1 of the first lens L1 becomes too large, and the surface shape is too curved, so that the size of the first lens L1 in the optical axis 110 direction becomes too large, and the first lens L1 occupies too large a space, which hinders the reduction in the total length of the optical system 100, and is disadvantageous for the miniaturization of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: TTL/ImgH is less than or equal to 1.7; wherein, 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, and ImgH is half of the image height corresponding to the maximum field angle of the optical system 100. Specifically, TTL/ImgH may be: 1.514, 1.532, 1.539, 1.554, 1.562, 1.593, 1.605, 1.633, 1.656 or 1.670. When the above conditional expressions are satisfied, the ratio of the total optical length and the half-image height of the optical system 100 can be reasonably configured, so that the total system length of the optical system 100 is effectively compressed, and the miniaturization design of the optical system 100 is facilitated. In addition, ImgH determines the size of the imaging size of the optical system 100, and when the above conditional expressions are satisfied, the system can match with a large-sized photosensitive element, thereby realizing large-image-plane, high-pixel imaging. If the upper limit of the above conditional expression is exceeded, the total length of the optical system 100 is too long, which is disadvantageous for the compact design of the optical system 100, and makes it difficult for the optical system 100 to match with a slim electronic device.

In some embodiments, the optical system 100 satisfies the conditional expression: FNO/tan (HFOV) is not less than 1.7 and not more than 2.0; where FNO is the f-number of the optical system 100, and HFOV is half of the maximum field angle of the optical system 100. Specifically, FNO/tan (hfov) may be: 1.797, 1.803, 1.825, 1.866, 1.876, 1.899, 1.925, 1.964, 1.977, or 1.987. When the above conditional expressions are satisfied, the f-number and the field angle of the optical system 100 can be reasonably configured, so that the optical system 100 has a large aperture, which is beneficial to correcting the aberration of the optical system 100 and improving the imaging quality of the optical system 100. If the upper limit of the above conditional expression is exceeded, the f-number of the optical system 100 is too large, the light incident amount decreases, and the imaging quality of the optical system 100 in a low-light environment tends to be deteriorated. If the value is lower than the lower limit of the above conditional expression, the f-number of the optical system 100 is too small, so that the effective light-passing aperture of the diaphragm is too large, and it is difficult to effectively adjust the marginal rays of the field of view, which is not favorable for correcting the aberration of the optical system 100.

It should be noted that, in the present application, 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 region on the imaging plane of the optical system 100 has a horizontal direction and a diagonal direction, and ImgH may be understood as a half of the length of the effective pixel region on the imaging plane of the optical system 100 in the diagonal direction, and HFOV may be understood as a half of the maximum field angle of the optical system 100 in the diagonal direction.

In some embodiments, the optical system 100 satisfies the conditional expression: v3+ V4+ V5 is more than or equal to 90 and less than or equal to 110; v3 is the abbe number of the third lens L3 under d-line, V4 is the abbe number of the fourth lens L4 under d-line, and V5 is the abbe number of the fifth lens L5 under d-line, i.e., V3, V4, and V5 are the abbe numbers of the third lens L3, the fourth lens L4, and the fifth lens L5 under the reference wavelength of 587.56nm, respectively. Specifically, V3+ V4+ V5 may be: 98.888, 99.125, 101.552, 102.376, 103.645, 105.285, 106.968, 107.332, 107.453, or 108.279. When the above conditional expressions are satisfied, abbe numbers of the third lens L3, the fourth lens L4, and the fifth lens L5 can be reasonably arranged, so that chromatic aberration of the optical system 100 is effectively corrected, and imaging quality of the optical system 100 is improved. If the abbe number of the third lens L3, the fourth lens L4, and the fifth lens L5 is too small below the lower limit of the conditional expression, the third lens L3, the fourth lens L4, and the fifth lens L5 are not sufficiently corrected for chromatic aberration, and the imaging quality of the optical system 100 is likely to be degraded. If the upper limit of the above conditional expression is exceeded, the abbe numbers of the third lens L3, the fourth lens L4, and the fifth lens L5 are too large, resulting in an increase in the cost of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: f2/R3 is more than or equal to 1.8 and less than or equal to 2.0; where f2 is the effective focal length of the second lens L2, and R3 is the radius of curvature of the object-side surface S3 of the second lens L2 at the optical axis 110. Specifically, f2/R3 may be: 1.836, 1.852, 1.864, 1.882, 1.893, 1.905, 1.965, 1.973, 1.979 or 1.987. When the above conditional expressions are satisfied, the second lens element L2 provides sufficient positive refractive power for the optical system 100, which is favorable for shortening the total length of the optical system 100, and meanwhile, the refractive power of the second lens element L2 is not too strong, which is favorable for correcting the spherical aberration of the optical system 100. When the upper limit of the above conditional expression is exceeded, the effective focal length of the second lens element L2 is too long, and the positive refractive power is too weak, which is not favorable for shortening the total length of the optical system 100. If the refractive power is lower than the lower limit of the conditional expression, the positive refractive power of the second lens element L2 is too strong, which makes the spherical aberration of the optical system 100 difficult to correct, and is not favorable for improving the imaging quality of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: CT2/CT1 is more than or equal to 2.5 and less than or equal to 3.5; the thickness of the second lens element L2 on the optical axis 110, i.e., the center thickness of the second lens element L2, is CT2, and the thickness of the first lens element L1 on the optical axis 110, i.e., the center thickness of the first lens element L1, is CT 1. Specifically, CT2/CT1 may be: 2.529, 2.616, 2.751, 2.863, 2.964, 3.021, 3.112, 3.220, 3.365, or 3.486. When the above conditional expressions are satisfied, the thickness of the first lens L1 on the optical axis 110 is small, the surface shape is smooth, and it is advantageous to reduce the space occupation ratio of the first lens L1 in the optical system 100, and further, it is advantageous to miniaturize the optical system 100. If the upper limit of the above conditional expression is exceeded, the size of the second lens L2 on the optical axis 110 is too large, which is disadvantageous for the compact design of the optical system 100. Below the lower limit of the above conditional expression, the size of the first lens L1 on the optical axis 110 is too large, which increases the total system length of the optical system 100, and is not favorable for the miniaturization design of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: -10 ≤ (R7+ R8)/(R7-R8) 1.5; wherein R7 is a radius of curvature of the object-side surface S7 of the fourth lens element L4 along the optical axis 110, and R8 is a radius of curvature of the image-side surface S8 of the fourth lens element L4 along the optical axis 110. Specifically, (R7+ R8)/(R7-R8) may be: -9.820, -8.324, -7.635, -6.558, -5.374, -4.615, -3.669, -2.112, -1.036, or 1.339. The fourth lens L4 is located in the middle of the optical system 100, and when the above conditional expressions are satisfied, the surface curvature degrees of the object-side surface S7 and the image-side surface S8 of the fourth lens L4 can be reasonably increased, which is beneficial for the fourth lens L4 to cooperate with the rest lenses of the optical system 100 to form images, and further beneficial for correcting the aberration of the optical system 100 and improving the imaging quality of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: Y1/Y2 is less than or equal to 1.5; y1 is half of the maximum effective clear aperture of the object-side surface S1 of the first lens L1, and Y2 is half of the maximum effective clear aperture of the object-side surface S3 of the second lens L2. Specifically, Y1/Y2 may be: 1.373, 1.376, 1.380, 1.388, 1.392, 1.395, 1.401, 1.405, 1.411 or 1.425. When the above conditional expressions are satisfied, the difference between the maximum effective light-passing apertures of the object-side surface S1 of the first lens L1 and the object-side surface S3 of the second lens L2 can be reduced, so that the deflection angle is not too large when light enters the optical system 100, which is beneficial to reducing the generation of aberration. Exceeding the upper limit of the conditional expression, the difference between the maximum effective light-passing apertures of the object-side surface S1 of the first lens L1 and the object-side surface S3 of the second lens L2 is too large, which easily increases the tolerance sensitivity of the first lens L1 and the second lens L2, and further reduces the molding yield of the first lens L1 and the second lens L2.

In some embodiments, the optical system 100 satisfies the conditional expression: r12/f6 is more than or equal to-0.65 and less than or equal to-0.45; wherein R12 is the radius of curvature of the image-side surface S12 of the sixth lens element L6 along the optical axis 110, and f6 is the effective focal length of the sixth lens element L6. Specifically, R12/f6 may be: -0.608, -0.595, -0.564, -5.551, -0.531, -0.523, -0.502, -4.998, -4.925 or-0.487. The sixth lens element L6 provides positive refractive power to the optical system 100, and when the above conditional expressions are satisfied, the image-side surface S12 of the sixth lens element L6 is convex at the paraxial region 110, which is favorable for the sixth lens element L6 and the seventh lens element L7 to cooperate with each other, so as to shorten the back focal length of the optical system 100 and effectively correct the distortion of the optical system 100.

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 2, fig. 1 is a schematic diagram of the optical system 100 in the first embodiment, and the optical system 100 includes, in order from an object side to an image side, a first lens element L1 with negative refractive power, a second lens element L2 with positive refractive power, a third lens element L3 with negative refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with negative refractive power, a sixth lens element L6 with positive refractive power, and a seventh lens element L7 with negative refractive power. Fig. 2 is a graph of the spherical aberration, astigmatism and distortion of the optical system 100 in the first embodiment, in which the reference wavelength of the astigmatism diagram and the distortion diagram is 587.56nm (d-line), from left to right, and the same is applied to other embodiments.

The object-side surface S1 of the first lens element L1 is concave near the optical axis 110 and convex near the circumference;

the image-side surface S2 of the first lens element L1 is concave at a paraxial region 110 and concave at a peripheral region;

the object-side surface S3 of the second lens element L2 is convex near the optical axis 110 and convex near the circumference;

the image-side surface S4 of the second lens element L2 is convex near the optical axis 110 and concave near the circumference;

the object-side surface S5 of the third lens element L3 is convex near the optical axis 110 and convex near the circumference;

the image-side surface S6 of the third lens element L3 is concave at a paraxial region 110 and concave at a peripheral region;

the object-side surface S7 of the fourth lens element L4 is concave near the optical axis 110 and concave near the circumference;

the image-side surface S8 of the fourth lens element L4 is convex near the optical axis 110 and convex near the circumference;

the object-side surface S9 of the fifth lens element L5 is concave near the optical axis 110 and concave near the circumference;

the image-side surface S10 of the fifth lens element L5 is convex near the optical axis 110 and convex near the circumference;

the object-side surface S11 of the sixth lens element L6 is concave near the optical axis 110 and convex near the circumference;

the image-side surface S12 of the sixth lens element L6 is convex near the optical axis 110 and concave near the circumference;

the object-side surface S13 of the seventh lens element L7 is convex near the optical axis 110 and concave near the circumference;

the image-side surface S14 of the seventh lens element L7 is concave near the optical axis 110 and convex near the circumference.

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, the sixth lens L6, and the seventh lens L7 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 concave near the circumference, it is understood that the surface is concave near the region of 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 the convex shape of the central area is firstly transited to the concave shape, and then the central area becomes the 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, the sixth lens L6 and the seventh lens L7 are all made of plastic.

Further, the optical system 100 satisfies the conditional expression: 0.8 | SAG1/f1| × (100); where SAG1 is the rise at the maximum effective clear aperture of the object-side surface S1 of the first lens L1, and f1 is the effective focal length of the first lens L1. When the above conditional expressions are satisfied, the object-side surface S1 of the first lens L1 tends to be gentle, which is favorable for shortening the dimension of the first lens L1 in the optical axis 110 direction, and further shortening the total system length of the optical system 100, thereby realizing the miniaturization design of the optical system 100. Meanwhile, the object side surface S1 of the first lens L1 is flat and gentle in surface shape and small in curvature, and injection molding of the first lens L1 is facilitated.

The optical system 100 satisfies the conditional expression: TTL/ImgH is 1.559; wherein, 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, and ImgH is half of the image height corresponding to the maximum field angle of the optical system 100. When the above conditional expressions are satisfied, the ratio of the total optical length and the half-image height of the optical system 100 can be reasonably configured, so that the total system length of the optical system 100 is effectively compressed, and the miniaturization design of the optical system 100 is facilitated. In addition, ImgH determines the size of the imaging size of the optical system 100, and when the above conditional expressions are satisfied, the system can match with a large-sized photosensitive element, thereby realizing large-image-plane, high-pixel imaging.

The optical system 100 satisfies the conditional expression: FNO/tan (hfov) ═ 1.987; where FNO is the f-number of the optical system 100, and HFOV is half of the maximum field angle of the optical system 100. When the above conditional expressions are satisfied, the f-number and the field angle of the optical system 100 can be reasonably configured, so that the optical system 100 has a large aperture, which is beneficial to correcting the aberration of the optical system 100 and improving the imaging quality of the optical system 100. Meanwhile, the f-number of the optical system 100 is not too large, so that the optical system 100 has sufficient light input quantity, and the imaging quality of the optical system 100 in a weak light environment is improved.

The optical system 100 satisfies the conditional expression: v3+ V4+ V5 ═ 98.888; v3 is the abbe number of the third lens L3 under d-line, V4 is the abbe number of the fourth lens L4 under d-line, and V5 is the abbe number of the fifth lens L5 under d-line. When the above conditional expressions are satisfied, abbe numbers of the third lens L3, the fourth lens L4, and the fifth lens L5 can be reasonably arranged, so that chromatic aberration of the optical system 100 is effectively corrected, and imaging quality of the optical system 100 is improved. Meanwhile, abbe numbers of the third lens L3, the fourth lens L4 and the fifth lens L5 are not too large, which is beneficial to reducing the cost of the optical system 100.

The optical system 100 satisfies the conditional expression: f2/R3 ═ 1.836; where f2 is the effective focal length of the second lens L2, and R3 is the radius of curvature of the object-side surface S3 of the second lens L2 at the optical axis 110. When the above conditional expressions are satisfied, the second lens element L2 provides sufficient positive refractive power for the optical system 100, which is favorable for shortening the total length of the optical system 100, and meanwhile, the refractive power of the second lens element L2 is not too strong, which is favorable for correcting the spherical aberration of the optical system 100.

The optical system 100 satisfies the conditional expression: CT2/CT 1-3.055; the thickness of the second lens element L2 on the optical axis 110, i.e., the center thickness of the second lens element L2, is CT2, and the thickness of the first lens element L1 on the optical axis 110, i.e., the center thickness of the first lens element L1, is CT 1. When the above conditional expressions are satisfied, the thickness of the first lens L1 on the optical axis 110 is small, the surface shape is smooth, and it is advantageous to reduce the space occupation ratio of the first lens L1 in the optical system 100, and further, it is advantageous to miniaturize the optical system 100.

The optical system 100 satisfies the conditional expression: (R7+ R8)/(R7-R8) ═ 1.027; wherein R7 is a radius of curvature of the object-side surface S7 of the fourth lens element L4 along the optical axis 110, and R8 is a radius of curvature of the image-side surface S8 of the fourth lens element L4 along the optical axis 110. The fourth lens L4 is located in the middle of the optical system 100, and when the above conditional expressions are satisfied, the surface curvature degrees of the object-side surface S7 and the image-side surface S8 of the fourth lens L4 can be reasonably increased, which is beneficial for the fourth lens L4 to cooperate with the rest lenses of the optical system 100 to form images, and further beneficial for correcting the aberration of the optical system 100 and improving the imaging quality of the optical system 100.

The optical system 100 satisfies the conditional expression: Y1/Y2 ═ 1.383; y1 is half of the maximum effective clear aperture of the object-side surface S1 of the first lens L1, and Y2 is half of the maximum effective clear aperture of the object-side surface S3 of the second lens L2. When the above conditional expressions are satisfied, the difference between the maximum effective light-passing apertures of the object side surfaces of the first lens L1 and the second lens L2 can be reduced, so that the deflection angle is not too large when light enters the optical system 100, which is beneficial to reducing aberration, and meanwhile, the tolerance sensitivities of the first lens L1 and the second lens L2 can be reduced, and the molding yield of the first lens L1 and the second lens L2 is improved.

The optical system 100 satisfies the conditional expression: r12/f6 ═ 0.487; wherein R12 is the radius of curvature of the image-side surface S12 of the sixth lens element L6 along the optical axis 110, and f6 is the effective focal length of the sixth lens element L6. The sixth lens element L6 provides positive refractive power to the optical system 100, and when the above conditional expressions are satisfied, the image-side surface S12 of the sixth lens element L6 is convex at the paraxial region 110, which is favorable for the sixth lens element L6 and the seventh lens element L7 to cooperate with each other, so as to shorten the back focal length of the optical system 100 and effectively correct the distortion of the optical system 100.

In addition, the parameters of the optical system 100 are given in table 1. Among them, the image plane S17 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 S17 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 at the optical axis 110 for the corresponding surface number. Surface number 1 and surface number 2 are the object-side surface S1 and the image-side surface S2 of the first lens L1, respectively, that is, in the same lens, the surface with the smaller surface number is the object-side surface, and the surface with the larger surface number is the image-side surface. The first 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 L8, but the distance from the image-side surface S14 of the seventh lens L7 to the image surface S17 is kept constant at this time.

In the first embodiment, the total effective focal length f of the optical system 100 is 4.88mm, the f-number FNO is 1.776, one-half of the maximum field angle HFOV is 41.8 °, and the total optical length TTL of the optical system 100 is 7.0 mm.

And the reference wavelengths of the focal length, refractive index and abbe number of each lens are 587.56nm (d-line), and the same applies to other embodiments.

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. In which the surface numbers 1-14 represent image side surfaces or object side surfaces S1-S14, respectively. And K-a20 from top to bottom respectively indicate the types of aspheric coefficients, where K indicates a conic coefficient, a4 indicates a quartic aspheric coefficient, a6 indicates a sextic aspheric coefficient, A8 indicates an octal aspheric coefficient, and so on. In addition, the aspheric coefficients may use, but are not limited to, the following formula:

wherein, Z is the distance from the corresponding point on the aspheric surface to the plane tangent to the surface vertex in the direction of the optical axis 110, r is the perpendicular 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 type 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 the Normalized Pupil coordinate (Normalized Pupil Coordinator) from the Pupil center to the Pupil edge, and the abscissa represents the distance (in mm) of the imaging plane from 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, in which the S curve represents sagittal field curvature at 587.56nm, and the T curve represents meridional field curvature at 587.56 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 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 first lens element L1 with negative refractive power, a second lens element L2 with positive refractive power, a third lens element L3 with negative refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with negative refractive power, a sixth lens element L6 with positive refractive power, and a seventh lens element L7 with negative refractive power. Fig. 4 is a graph of spherical aberration, astigmatism and distortion of the optical system 100 in the second embodiment, from left to right.

the image-side surface S4 of the second lens element L2 is concave at a paraxial region 110 and concave at a peripheral region;

the object-side surface S7 of the fourth lens element L4 is convex near the optical axis 110 and convex near the circumference;

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

the object-side surface S11 of the sixth lens element L6 is concave near the optical axis 110 and concave near the circumference;

the image-side surface S12 of the sixth lens element L6 is convex near the optical axis 110 and convex near the circumference;

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:

\|SAG1/f1\|*100	1.1	CT2/CT1	2.529
				TTL/ImgH	1.670	(R7+R8)/(R7-R8)	-0.584
FNO/tan(HFOV)	1.987	Y1/Y2	1.425
				V3+V4+V5	98.888	R12/f6	-0.493
f2/R3	1.891

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 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 first lens element L1 with negative refractive power, a second lens element L2 with positive 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, a sixth lens element L6 with positive refractive power, and a seventh lens element L7 with negative refractive power. Fig. 6 is a graph of spherical aberration, astigmatism and distortion of the optical system 100 in the third embodiment, from left to right.

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

\|SAG1/f1\|*100	1.0	CT2/CT1	3.005
				TTL/ImgH	1.604	(R7+R8)/(R7-R8)	1.339
FNO/tan(HFOV)	1.965	Y1/Y2	1.405
				V3+V4+V5	98.888	R12/f6	-0.522
f2/R3	1.987

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 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 first lens element L1 with negative refractive power, a second lens element L2 with positive refractive power, a third lens element L3 with negative refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with negative refractive power, a sixth lens element L6 with positive refractive power, and a seventh lens element L7 with negative refractive power. Fig. 8 is a graph showing the spherical aberration, astigmatism and distortion of the optical system 100 in the fourth embodiment in order from left to right.

the object-side surface S7 of the fourth lens element L4 is convex near the optical axis 110 and concave near the circumference;

the object-side surface S11 of the sixth lens element L6 is convex near the optical axis 110 and concave near the circumference;

the object-side surface S13 of the seventh lens element L7 is concave near the optical axis 110 and concave near the circumference;

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

\|SAG1/f1\|*100	0.5	CT2/CT1	3.064
				TTL/ImgH	1.581	(R7+R8)/(R7-R8)	0.886
FNO/tan(HFOV)	1.889	Y1/Y2	1.373
				V3+V4+V5	101.841	R12/f6	-0.608
f2/R3	1.870

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 diagram of the optical system 100 in the fifth embodiment, and the optical system 100 includes, in order from an object side to an image side, a first lens element L1 with negative refractive power, a second lens element L2 with positive refractive power, a third lens element L3 with negative refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with negative refractive power, a sixth lens element L6 with positive refractive power, and a seventh lens element L7 with negative refractive power. Fig. 10 is a graph showing the spherical aberration, astigmatism and distortion of the optical system 100 in the fifth embodiment in order from left to right.

the image-side surface S4 of the second lens element L2 is concave near the optical axis 110 and convex near the circumference;

the image-side surface S8 of the fourth lens element L4 is concave near the optical axis 110 and convex near the circumference;

the object-side surface S9 of the fifth lens element L5 is convex near the optical axis 110 and concave near the circumference;

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.

Sixth embodiment

Referring to fig. 11 and 12, fig. 11 is a schematic diagram of the optical system 100 in the sixth embodiment, in which the optical system 100 includes, in order from an object side to an image side, a first lens element L1 with negative refractive power, a second lens element L2 with positive refractive power, a third lens element L3 with negative refractive power, a fourth lens element L4 with positive refractive power, a fifth lens element L5 with positive refractive power, a sixth lens element L6 with positive refractive power, and a seventh lens element L7 with negative refractive power. Fig. 12 is a graph showing the spherical aberration, astigmatism and distortion of the optical system 100 in the sixth embodiment in order from left to right.

the image-side surface S8 of the fourth lens element L4 is concave at a paraxial region 110 and concave at a peripheral region;

the object-side surface S11 of the sixth lens element L6 is convex near the optical axis 110 and convex near the circumference;

In addition, the parameters of the optical system 100 are given in table 11, and the definitions of the parameters can be obtained from the first embodiment, which is not described herein.

TABLE 11

Further, the aspheric coefficients of the image-side surface or the object-side surface of each lens of the optical system 100 are given in table 12, and the definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

TABLE 12

\|SAG1/f1\|*100	1.2	CT2/CT1	3.486
				TTL/ImgH	1.514	(R7+R8)/(R7-R8)	-9.820
FNO/tan(HFOV)	1.797	Y1/Y2	1.387
				V3+V4+V5	108.279	R12/f6	-0.563
f2/R3	1.838

in addition, as can be seen from the aberration diagram in fig. 12, 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. 13, 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 S17 of the optical system 100. The image capturing module 200 may further include an infrared filter L8, and the infrared filter L8 is disposed between the image side surface S14 and the image surface S17 of the seventh lens element L7. 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, which is beneficial to reducing the total length of the optical system 100, thereby being beneficial to the miniaturization design of the image capturing module 200.

Referring to fig. 13 and 14, 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. The image capturing module 200 is adopted in the electronic device 300, which is beneficial to the miniaturization design 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 shall be subject to the appended claims.

Claims

1. An optical system comprising, in order from an object side to an image side:

a fourth lens element with positive refractive power;

a fifth lens element with refractive power;

a sixth lens element with positive refractive power;

a seventh lens element with negative refractive power;

and the optical system satisfies the following conditional expression:

|SAG1/f1|*100≤2；

wherein SAG1 is the rise in sagittal height at the maximum effective clear aperture of the object side of the first lens, and f1 is the effective focal length of the first lens.

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

TTL/ImgH≤1.7；

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

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

1.7≤FNO/tan(HFOV)≤2.0；

wherein FNO is the f-number of the optical system, and HFOV is half of the maximum field angle of the optical system.

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

90≤V3+V4+V5≤110；

wherein V3 is the abbe number of the third lens under d-line, V4 is the abbe number of the fourth lens under d-line, and V5 is the abbe number of the fifth lens under d-line.

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

1.8≤f2/R3≤2.0；

wherein f2 is an effective focal length of the second lens, and R3 is a radius of curvature of an object-side surface of the second lens at an optical axis.

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

2.5≤CT2/CT1≤3.5；

wherein CT2 is the thickness of the second lens element on the optical axis, and CT1 is the thickness of the first lens element on the optical axis.

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

-10≤(R7+R8)/(R7-R8)≤1.5；

wherein R7 is a radius of curvature of an object-side surface of the fourth lens element at an optical axis, and R8 is a radius of curvature of an image-side surface of the fourth lens element at the optical axis.

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

Y1/Y2≤1.5；

y1 is half of the maximum effective clear aperture of the object side surface of the first lens, and Y2 is half of the maximum effective clear aperture of the object side surface of the second lens.

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

-0.65≤R12/f6≤-0.45；

wherein R12 is a radius of curvature of an image-side surface of the sixth lens at an optical axis, and f6 is an effective focal length of the sixth lens.

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.