CN113484987B

CN113484987B - Optical system, image capturing module and electronic equipment

Info

Publication number: CN113484987B
Application number: CN202110779425.7A
Authority: CN
Inventors: 乐宇明; 蔡雄宇; 兰宾利; 赵迪
Original assignee: Tianjin OFilm Opto Electronics Co Ltd
Current assignee: Jiangxi Oufei Optics Co ltd
Priority date: 2021-07-09
Filing date: 2021-07-09
Publication date: 2022-11-18
Anticipated expiration: 2041-07-09
Also published as: CN113484987A

Abstract

The invention relates to an optical system, an image capturing module and an electronic device. The 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 and a concave image-side surface; a second lens element with refractive power having a concave image-side surface at paraxial region; a third lens element with refractive power; a fourth lens element with positive refractive power having a convex object-side surface and a convex image-side surface; a fifth lens element with positive refractive power having a convex object-side surface at paraxial region; a sixth lens element with negative refractive power having a concave image-side surface at paraxial region; the optical system satisfies the conditional expression: 10 to (d 12/f) 100 to 22.5; d12 is the distance on the optical axis from the image-side surface of the first lens element to the object-side surface of the second lens element, and f is the effective focal length of the optical system. The optical system can realize both the long-focus characteristic and the high imaging quality.

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 continuous development of automobile safety technologies such as an auxiliary driving technology, automatic driving and unmanned driving, the application of the vehicle-mounted camera is more and more popularized. The vehicle-mounted lens has different mounting positions and different functions, wherein the forward-looking camera provides reference for people in a blind spot area except a human eye observable area due to the fact that images at a longer distance need to be observed, so that a driver can master the front road condition in real time in the driving process and guarantee safe driving, and therefore the forward-looking camera needs to have a larger focal length. However, the conventional forward-looking camera has a long focal length, so that the imaging quality is easily degraded, and it is difficult to achieve both the long-focus characteristic and the high imaging quality.

Disclosure of Invention

Accordingly, it is desirable to provide an optical system, an image capturing module and an electronic device for solving the problem that the conventional front-view camera is difficult to achieve both the telephoto characteristic and the high imaging quality.

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 and a concave image-side surface;

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

a third lens element with refractive power;

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

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

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

and the optical system satisfies the following conditional expression:

10≤(d12/f)*100≤22.5；

wherein d12 is a distance on an optical axis from an image side surface of the first lens element to an object side surface of the second lens element, and f is an effective focal length of the optical system.

In the optical system, the first lens element has positive refractive power, and the object-side surface of the first lens element is convex at a position close to the optical axis, so that the first lens element can effectively converge light, thereby providing a main convergence capability for the system, facilitating the formation of a telescopic structure, and avoiding the over-long total length of the system which is not beneficial to the assembly of the system. The image side surface of the first lens is a concave surface at the position of a paraxial region, which is beneficial to controlling the trend of a light path, thereby avoiding overlarge effective aperture of the second lens. The fourth lens element with positive refractive power can further converge light rays, so that the surface shapes of the lenses on the image side of the fourth lens element are more smooth, and the deviation of the incident angles and the exit angles of the light rays in different fields of view is reduced, thereby reducing the sensitivity of the system. The fifth lens element with positive refractive power has a convex object-side surface at paraxial region, and is matched with each lens element in the object space, thereby improving the convergence of the fifth lens element on the object-side light, reducing the diameter of the rear end of the lens, and shortening the total length of the optical system. The sixth lens element with negative refractive power has a concave image-side surface near the optical axis, which facilitates the light to enter the image plane at a proper angle and avoids generating excessive aberration.

When the optical system has the refractive power and the surface type characteristics and meets the condition formula, the air space between the first lens and the second lens and the effective focal length of the optical system can be reasonably configured, so that the optical system is favorable for having the telephoto characteristic, and simultaneously, the aberration of the optical system is favorable for being corrected, thereby considering both the telephoto characteristic and the realization of high imaging quality, and in addition, the structure of the optical system is also favorable for being more compact, so that the miniaturization design is favorable for being realized. The light beam diverged by the first lens can be restrained from being greatly expanded by meeting the upper limit of the conditional expression, so that the light can be effectively converged on an imaging surface without enhancing the convergence effect of each lens on the image side of the first lens on the light, the aberration of the optical system can be well corrected, and the imaging quality of the optical system is improved. Through satisfying the lower limit of conditional expression, the light beam through first lens fully diverges and incides the second lens, is favorable to proofreading and correct optical system's off-axis aberration, promotes optical system's imaging quality.

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

1.5≤f1/f≤10.2；

wherein f1 is an effective focal length of the first lens. When the conditional expressions are satisfied, the refractive power ratio of the first lens in the optical system can be reasonably configured, so that the aberration of the optical system can be corrected, and the imaging resolution of the optical system can be improved. If the effective focal length of the first lens element is too large, the refractive power is insufficient, which is not favorable for suppressing the generation of high-order aberration, thereby easily generating aberrations such as high-order spherical aberration and coma aberration, and reducing the resolution and imaging quality of the optical system; when the refractive power of the first lens element is too high, the light beam width is rapidly reduced, and the incident angle of the light beam incident on the image side lens element is enlarged, so that the burden of the image side lens element on reducing the light beam angle of the light beam exiting optical system is increased, the difficulty of manufacturing the image side lens element is increased, and the aberration of the image side lens element is not corrected.

1.9≤f4/CT4≤10；

wherein f4 is an effective focal length of the fourth lens element, and CT4 is a thickness of the fourth lens element on the optical axis. When the conditional expression is met, the ratio of the effective focal length to the center thickness of the fourth lens can be reasonably configured, so that the tolerance sensitivity of the center thickness of the fourth lens is favorably reduced, the processing technology difficulty of the fourth lens is favorably reduced, the assembly yield of an optical system is favorably improved, and the production cost is reduced; and simultaneously, the total length of the optical system is favorably shortened. Below the lower limit of the above conditional expression, the central thickness of the fourth lens is too large, which results in too large weight of the fourth lens, and is not favorable for the light and thin design of the optical system.

-20mm≤f5*f6/f≤-5.5mm；

wherein f5 is an effective focal length of the fifth lens, and f6 is an effective focal length of the sixth lens. When the condition is satisfied, the refractive power ratio of the fifth lens element and the sixth lens element in the optical system can be reasonably configured, so that the positive refractive power of the fifth lens element and the negative refractive power of the sixth lens element can be effectively matched, the total length of the optical system can be shortened, the aberrations of the fifth lens element and the sixth lens element can be effectively corrected, and the imaging quality of the optical system can be improved.

1.8≤TTL/f≤2.3；

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. When the conditional expressions are satisfied, the ratio of the total optical length to the effective focal length of the optical system can be reasonably configured, so that the optical system is favorable for realizing the miniaturization design of the optical system, and meanwhile, the optical system is favorable for realizing the long-focus characteristic and having a reasonable field angle range, so that enough object space information can be acquired. If the upper limit of the conditional expression is exceeded, the total optical length of the optical system is too long, which is not beneficial to realizing miniaturization design; below the lower limit of the above conditional expression, the effective focal length of the optical system is too long, resulting in insufficient field angle range of the optical system, and it is difficult to obtain sufficient object space information.

0.4≤CT6/SAG62≤5；

wherein CT6 is the thickness of the sixth lens element on the optical axis, and SAG62 is the rise of the maximum effective aperture of the image-side surface of the sixth lens element, i.e. the distance from the maximum effective aperture of the image-side surface of the sixth lens element to the intersection point of the image-side surface of the sixth lens element and the optical axis in the optical axis direction. When the conditional expressions are met, the ratio of the center thickness to the rise of the sixth lens can be reasonably configured, so that the center thickness of the sixth lens cannot be too large, the image side surface of the sixth lens cannot be too curved, the tolerance sensitivity of the sixth lens is favorably reduced, and the forming yield of the sixth lens is improved. The lower limit of the conditional expression is lower, the object side surface and the image side surface of the sixth lens are too curved, the processing difficulty of the sixth lens is high, and the production cost of the sixth lens is increased; meanwhile, the object-side surface and the image-side surface of the sixth lens are too curved, so that edge aberration is easily generated, and the improvement of the imaging quality of the optical system is not facilitated. Exceeding the upper limit of the above conditional expressions, the center thickness of the sixth lens is too large, which is not favorable for the light and thin design of the optical system.

0.6≤ImgH*2/f≤1；

wherein ImgH is half of the image height corresponding to the maximum field angle of the optical system. When the conditional expression is met, the ratio of the half-image height to the effective focal length of the optical system can be reasonably configured, the long-focus characteristic is realized, the distortion of the optical system is favorably corrected, and the imaging quality of the optical system is improved; in addition, the optical system is also favorable for being matched with a photosensitive element with larger size, so that the optical system has high pixels, and the imaging quality of the optical system is improved. Below the lower limit of the above conditional expression, the effective focal length of the optical system is too long, which easily causes severe negative distortion and reduces the imaging quality of the optical system. When the upper limit of the conditional expression is exceeded, the effective focal length of the optical system is too short, the tolerance sensitivity of each lens is increased, the manufacturability of the optical system is reduced, and meanwhile, the edge light rays are difficult to effectively converge on an imaging surface, so that the edge brightness is reduced.

In one embodiment, the optical system further includes an infrared filter disposed between the second lens and the third lens. The infrared filter is arranged, so that interference light can be filtered, and the interference light is prevented from reaching an imaging surface to influence normal imaging. Set up the infrared filter between second lens element and third lens element, be favorable to reducing the reflection image between infrared filter and the adjacent lens element and form the probability of ghost at the imaging surface, thereby be favorable to improving the ghost phenomenon, simultaneously, be favorable to reserving enough big air gap between second lens element and the third lens element, make the transition of light between second lens element and third lens element gentler, be favorable to optical system to the incident angle of chief ray and control, thereby can improve and lead to the different condition of imaging surface peripheral chief ray incident angle because of lens bending force is inhomogeneous everywhere, also be favorable to avoiding producing the demoulding phenomenon when adopting the infrared filter membrane in addition.

In one embodiment, the infrared filter is disposed between the second lens element and the third lens element, the object-side surface of the third lens element is concave at a paraxial region, and the optical system satisfies the following conditional expression:

|R31|≤7mm；

wherein R31 is a curvature radius of an object-side surface of the third lens at an optical axis. The object side surface of the third lens is a concave surface at the paraxial region, so that the ghost phenomenon formed by reflection between the infrared filter and the object side surface of the third lens is not obvious, and when the conditional expression is satisfied, the object side surface shape of the third lens is not too gentle, which is beneficial to further reducing the probability that the reflection image between the infrared filter and the object side surface of the third lens forms ghost at the imaging surface, thereby further improving the ghost phenomenon.

In one embodiment, the infrared filter is disposed on the image side of the sixth lens element, and the optical system satisfies the following conditional expression:

R62≤13mm；

wherein R62 is a curvature radius of an image-side surface of the sixth lens element at an optical axis. The image side surface of the sixth lens element is concave at the paraxial region, and when the above conditional expressions are satisfied, the image side surface profile of the sixth lens element is not too gentle, and when the infrared filter is disposed at the image side of the sixth lens element, the probability that a reflection image between the infrared filter and the image side surface of the sixth lens element forms a ghost image on the imaging surface is favorably reduced, so that the ghost image phenomenon is favorably improved.

An image capturing module includes a photosensitive element and the optical system according to any of the above embodiments, where the photosensitive element is disposed on an image side of the optical system. The image capturing module adopts the optical system, can give consideration to both the realization of long-focus characteristic and high imaging quality, and is beneficial to realizing miniaturization design.

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 module among the electronic equipment, can compromise the realization of long focal property and high imaging quality, also be favorable to realizing miniaturized design simultaneously.

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 view 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 structural diagram 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, as those skilled in the art will recognize without departing from the spirit and scope of the present invention.

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 to implicitly indicate 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 interconnected within two elements or in a relationship where two elements interact with each other unless otherwise specifically limited. 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.

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 element L1, a second lens element L2, a third lens element L3, a fourth lens element L4, a fifth lens element L5, and a sixth lens element L6. Specifically, the first lens element L1 includes an object-side surface S1 and an image-side surface S2, the second lens element L2 includes an object-side surface S3 and an image-side surface S4, the third lens element L3 includes an object-side surface S5 and an image-side surface S6, the fourth lens element L4 includes an object-side surface S7 and an image-side surface S8, the fifth lens element L5 includes an object-side surface S9 and an image-side surface S10, and the sixth lens element L6 includes an object-side surface S11 and an image-side surface S12. 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 coaxially disposed, and an axis common to the lenses in the optical system 100 is an optical axis 110 of the optical system 100.

The first lens element L1 has positive refractive power, and the object-side surface S1 of the first lens element L1 is convex at a position near the optical axis 110, so that the first lens element L1 can effectively converge light, and provide a main converging capability for the system, thereby facilitating formation of a telescopic structure, and avoiding the disadvantage of system assembly due to the overlong total length of the system. The image-side surface S2 of the first lens element L1 is concave at the paraxial region 110, which is beneficial to controlling the direction of the light path, thereby avoiding the effective aperture of the second lens element L2 being too large. The second lens element L2 with refractive power has a concave image-side surface S4 at a paraxial region 110 of the second lens element L2. The third lens element L3 has refractive power. The fourth lens element L4 with positive refractive power can further converge light, so that the surface shape of each lens element on the image side of the fourth lens element L4 is more smooth, and the deviation of the incident angle and the exit angle of light in different fields is reduced, thereby reducing the sensitivity of the system. The object-side surface S7 and the image-side surface S8 of the fourth lens element L4 are convex at the paraxial region 110. The fifth lens element L5 has positive refractive power, and the object-side surface S9 of the fifth lens element L5 at a position near the optical axis 110 is a convex surface, and is matched with each lens element in the object space, so as to facilitate improvement of the convergence capability of the fifth lens element L5 on the object-side light, thereby facilitating reduction of the rear end aperture of the lens, and further facilitating shortening of the total length of the optical system 100. The sixth lens element L6 with negative refractive power has a concave image-side surface S12 at the paraxial region 110, which is favorable for light to enter the image plane at a proper angle to avoid excessive aberration.

In addition, in some embodiments, the optical system 100 is provided with a stop STO, which may be disposed between the first lens L1 and the second lens L2, or between the second lens L2 and the third lens L3. In some embodiments, the optical system 100 further includes an infrared filter L7, and the infrared filter L7 includes an object side surface S13 and an image side surface S14. The infrared filter L7 may be an infrared cut filter, and is configured to filter interference light, so as to prevent the interference light from reaching the image plane S17 of the optical system 100 and affecting normal imaging. The infrared filter L7 may be disposed between the second lens element L2 and the third lens element L3, or disposed on the image side of the sixth lens element L6. When the infrared filter L7 is disposed between the second lens element L2 and the third lens element L3, it is favorable for improving the ghost phenomenon, and simultaneously, it is favorable for reserving a large enough air gap between the second lens element L2 and the third lens element L3, so that the transition of the light between the second lens element L2 and the third lens element L3 is more gradual, which is favorable for the control of the optical system 100 on the incident angle of the chief ray, thereby improving the condition of different incident angles of the chief ray around the imaging surface caused by the uneven refractive power of the lens, and in addition, it is also favorable for avoiding the occurrence of the film peeling phenomenon when the infrared filter film is adopted. When the ir filter L7 is disposed between the second lens L2 and the third lens L3, the stop STO can be disposed between the second lens L2 and the ir filter L7.

The optical system 100 further includes an image plane S17 located on the image side of the sixth lens L6, where the image plane S17 is an imaging plane of the optical system 100, and incident light can be imaged on the image plane S17 after being 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. In some embodiments, the optical system 100 further includes a protective glass L8 disposed on the image side of the sixth lens L6, the protective glass L8 includes an object side surface S15 and an image side surface S16, and the protective glass L8 is used for protecting the photosensitive element disposed on the image side of the sixth lens L6. When the infrared filter L7 is disposed on the image side of the sixth lens L6, the infrared filter L7 and the protective glass L8 are sequentially arranged.

In some embodiments, the object-side surface and the image-side surface of each lens of optical system 100 are 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. For example, referring to fig. 1, in the first embodiment, the object-side surface S1 of the first lens L1, the object-side surface S3 and the image-side surface S4 of the second lens L2, and the object-side surface S9 and the image-side surface S10 of the fifth lens L5 are aspheric surfaces, and other surfaces are spherical surfaces. The surface type arrangement of the lenses in other embodiments can be obtained from the description of the subsequent embodiments.

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 light and thin design of the optical system 100 can be realized by matching with the small size of the optical system 100. 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.

In some embodiments, any two lenses of the optical system 100 form a cemented lens, and the arrangement of the cemented lens is favorable for reducing chromatic aberration of the optical system, so as to improve the imaging quality of the optical system 100. For example, in some embodiments, a cemented lens is formed between the third lens L3 and the fourth lens L4. In other embodiments, a cemented lens is formed between the second lens L2 and the third lens L3, and a cemented lens is formed between the fifth lens L5 and the sixth lens L6.

It should be noted that the first lens L1 does not mean that only one lens exists, and in some embodiments, two or more lenses may exist 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, no cemented lens is formed between the lenses of the first lens L1, but the distance between the lenses is relatively fixed, in which 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: 10 to (d 12/f) 100 to 22.5; where d12 is a distance on the optical axis 110 from the image-side surface S2 of the first lens element L1 to the object-side surface S3 of the second lens element L2, and f is an effective focal length of the optical system 100. Specifically, (d 12/f) × 100 may be: 10.055, 11, 557, 12.354, 13.332, 15.024, 16.995, 18.332, 20.125, 22.001, or 22.475. When the above conditional expressions are satisfied, the air space between the first lens L1 and the second lens L2 and the effective focal length of the optical system 100 can be configured reasonably, which is favorable for the optical system 100 to have the telephoto characteristic, and is favorable for correcting the aberration of the optical system 100, thereby taking into account the realization of the telephoto characteristic and the high imaging quality, and in addition, is favorable for making the structure of the optical system 100 more compact, thereby being favorable for realizing the miniaturized design. By satisfying the upper limit of the conditional expression, the light beam that is diverged by the first lens L1 can be suppressed from being greatly expanded, so that the light beam can be effectively converged on the image plane without enhancing the converging effect of each lens on the light beam on the image side of the first lens L1, the aberration of the optical system 100 can be corrected well, and the imaging quality of the optical system 100 can be improved. By satisfying the lower limit of the conditional expression, the light beam passing through the first lens L1 is sufficiently diverged and enters the second lens L2, which is beneficial to correcting the off-axis 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: f1/f is more than or equal to 1.5 and less than or equal to 10.2; where f1 is the effective focal length of the first lens L1. Specifically, f1/f may be: 1.685, 2.332, 3.541, 4.332, 5.088, 6.748, 7.693, 8.663, 9.472, or 10.128. When the above conditional expressions are satisfied, the refractive power ratio of the first lens element L1 in the optical system 100 can be configured reasonably, so that the aberration of the optical system 100 can be corrected, and the imaging resolution of the optical system 100 can be improved. If the effective focal length of the first lens element L1 is too large, the refractive power is insufficient, which is not favorable for suppressing the generation of high-order aberrations, thereby easily generating aberrations such as high-order spherical aberration and coma aberration, and reducing the resolution and the imaging quality of the optical system 100; below the lower limit of the conditional expressions, the refractive power of the first lens element L1 is too strong, which causes the light beam width to shrink rapidly, and the incident angle of the light beam incident on the image space lens element is enlarged, thereby increasing the burden of the image space lens element on reducing the light angle of the light beam exiting from the optical system 100, which further causes the difficulty in manufacturing the image space lens element and is not favorable for the image space lens element to correct the aberration.

In some embodiments, the optical system 100 satisfies the conditional expression: f4/CT4 is more than or equal to 1.9 and less than or equal to 10; where f4 is an effective focal length of the fourth lens element L4, and CT4 is a thickness of the fourth lens element L4 on the optical axis 110. Specifically, f4/CT4 may be: 1.961, 2.553, 3.254, 3.854, 4.287, 5.554, 6.369, 7.517, 8.225, or 9.689. When the conditional expressions are satisfied, the ratio of the effective focal length to the center thickness of the fourth lens L4 can be reasonably configured, which is beneficial to reducing the tolerance sensitivity of the center thickness of the fourth lens L4, thereby being beneficial to reducing the difficulty of the processing technology of the fourth lens L4, further being beneficial to improving the assembly yield of the optical system 100 and reducing the production cost; while also contributing to a reduction in the overall length of the optical system 100. Below the lower limit of the conditional expression, the central thickness of the fourth lens L4 is too large, which results in too large weight of the fourth lens L4, and is not favorable for the light and thin design of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: f5 x f6/f is less than or equal to minus 5.5mm and is more than or equal to minus 20 mm; where f5 is the effective focal length of the fifth lens L5, and f6 is the effective focal length of the sixth lens L6. Specifically, f5 × f6/f may be: -19.711, -17.225, -15.203, -12.336, -11.028, -9.587, -8.037, -6.339, -6.028, or-5.736. When the above conditional expressions are satisfied, the refractive power ratio of the fifth lens element L5 and the sixth lens element L6 in the optical system 100 can be reasonably configured, so that the positive refractive power of the fifth lens element L5 and the negative refractive power of the sixth lens element L6 can be effectively matched, and further the total length of the optical system 100 is shortened, and at the same time, the fifth lens element L5 and the sixth lens element L6 can effectively correct the aberration therebetween, thereby improving the imaging quality of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: TTL/f is more than or equal to 1.8 and less than or equal to 2.3; 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, i.e., the total optical length of the optical system 100. Specifically, TTL/f can be: 1.839, 1.850, 1.864, 1.873, 1.899, 1.902, 1.915, 1.925, 1.943 or 1.950. When the above conditional expressions are satisfied, the ratio of the total optical length to the effective focal length of the optical system 100 can be configured reasonably, which is favorable for realizing the miniaturization design of the optical system 100, and is also favorable for realizing the long-focus characteristic and possessing a reasonable field angle range of the optical system 100, so that sufficient object space information can be acquired. Exceeding the upper limit of the above conditional expressions, the optical system 100 has an excessively long total optical length, which is not favorable for realizing a miniaturized design; below the lower limit of the above conditional expression, the effective focal length of the optical system 100 is too long, resulting in an insufficient field angle range of the optical system 100, and it is difficult to obtain sufficient object space information.

In some embodiments, the optical system 100 satisfies the conditional expression: CT6/SAG62 is more than or equal to 0.4 and less than or equal to 5; where CT6 is the thickness of the sixth lens L6 on the optical axis 110, SAG62 is the rise of the image-side surface S12 of the sixth lens L6 at the maximum effective aperture, that is, the distance from the maximum effective aperture of the image-side surface S12 of the sixth lens L6 to the intersection point of the image-side surface S12 of the sixth lens L6 and the optical axis 110 in the direction of the optical axis 110. Specifically, CT6/SAG62 may be: 0.416, 0.987, 1.521, 1.886, 2.325, 3.055, 3.697, 4.332, 4.510, or 4.660. When the above conditional expressions are satisfied, the ratio of the center thickness of the sixth lens L6 to the rise of the image-side surface S12 can be reasonably configured, so that the center thickness of the sixth lens L6 is not too large, and the surface shape of the image-side surface S12 of the sixth lens L6 is not too curved, which is beneficial to reducing the tolerance sensitivity of the sixth lens L6 and improving the forming yield of the sixth lens L6. Below the lower limit of the conditional expression, the object-side surface S11 and the image-side surface S12 of the sixth lens L6 are too curved, which makes the sixth lens L6 difficult to process and increases the production cost of the sixth lens L6; meanwhile, the object-side surface S11 and the image-side surface S12 of the sixth lens element L6 are too curved, which is likely to generate edge aberration, and is not favorable for improving the imaging quality of the optical system 100. Exceeding the upper limit of the above conditional expression, the center thickness of the sixth lens L6 is too large, which is disadvantageous for the light and thin design of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: imgH 2/f is not less than 0.6 and not more than 1; here, imgH is half the image height corresponding to the maximum field angle of the optical system 100. Specifically, imgH × 2/f may be: 0.628, 0.629, 0.630, 0.631, 0.632, 0.633 or 0.634. When the conditional expressions are satisfied, the ratio of the half-image height to the effective focal length of the optical system 100 can be reasonably configured, so that the long-focus characteristic is realized, the distortion of the optical system 100 is favorably corrected, and the imaging quality of the optical system 100 is improved; in addition, the optical system 100 can be matched with a photosensitive element with a larger size, so that the optical system 100 has high pixels, and the imaging quality of the optical system 100 is improved. Below the lower limit of the above conditional expression, the effective focal length of the optical system 100 is too long, which easily causes severe negative distortion, and reduces the imaging quality of the optical system 100. Exceeding the upper limit of the above conditional expression, the effective focal length of the optical system 100 is too short, which increases the tolerance sensitivity of each lens, resulting in a decrease in manufacturability of the optical system 100, and at the same time, the edge light is difficult to be effectively converged on the image plane, resulting in a decrease in edge brightness.

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, and the maximum field angle FOV can be understood as the maximum field angle in the diagonal direction of the optical system 100, and ImgH can be understood as a half of the length in the diagonal direction of the effective pixel area on the imaging plane of the optical system 100.

In some embodiments, at least one lens in the optical system 100 satisfies the conditional expression: vd is less than or equal to 30 or Vd is more than or equal to 70; where Vd is the Abbe number of the lens at a wavelength of 587.56nm (d-line). Satisfying the above conditional expressions is beneficial to better correcting chromatic aberration of the optical system 100 and improving imaging quality of the optical system 100. The abbe number settings of the respective lenses of the optical system 100 in the respective embodiments can be obtained by the description of the respective embodiments below.

In some embodiments, the infrared filter L7 is disposed between the second lens element L2 and the third lens element L3, the object-side surface S5 of the third lens element L3 is concave at a position near the optical axis 110, and the optical system 100 satisfies the following conditional expression: the | R31| is less than or equal to 7mm; where R31 is a curvature radius of the object-side surface S5 of the third lens element L3 at the optical axis 100. The object-side surface S5 of the third lens element L3 is concave at the paraxial region 110, and thus the ghost phenomenon caused by the reflection between the infrared filter L7 and the object-side surface S5 of the third lens element L3 is not obvious. When the conditional expressions are satisfied, the surface shape of the object side surface S5 of the third lens L3 is not too gentle, which is beneficial to further reducing the probability that the reflection image between the infrared filter L7 and the object side surface S5 of the third lens L3 forms a ghost on the imaging surface, thereby further improving the ghost phenomenon.

In some embodiments, the infrared filter L7 is disposed on the image side of the sixth lens L6, and the optical system 100 satisfies the following conditional expression: r62 is less than or equal to 13mm; where R62 is a curvature radius of the image-side surface S12 of the sixth lens element L6 at the optical axis 110. The image-side surface S12 of the sixth lens element L6 is concave at the paraxial region 110, and when the above conditional expressions are satisfied, the shape of the image-side surface S12 of the sixth lens element L6 is not too smooth, so that when the ir-filter L7 is disposed at the image-side of the sixth lens element L6, the probability of the reflected image between the ir-filter L7 and the image-side surface S12 of the sixth lens element L6 forming a ghost image on the image plane is reduced, thereby improving the ghost phenomenon.

In the following embodiments, the reference wavelengths of the effective focal length values of the first, second and fifth embodiments are 546.074nm, and the reference wavelengths of the effective focal length values of the third and fourth embodiments are 550nm.

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 first lens element L1 with positive refractive power, a second lens element L2 with positive refractive power, a stop STO, an ir-filter L7, 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 negative refractive power, and a protective glass L8, where the third lens element L3 is cemented with the fourth lens element L4. Fig. 2 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the first embodiment, which is sequentially from left to right, wherein the reference wavelength of the astigmatism graph and the distortion graph is 546.074nm.

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 convex 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 concave 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 convex 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 concave at the paraxial region 110, and the image-side surface S12 is concave at the paraxial region 110.

The object-side surface S1 of the first lens L1, the object-side surface S3 and the image-side surface S4 of the second lens L2, and the object-side surface S9 and the image-side surface S10 of the fifth lens L5 are aspheric, and the object-side surface S2 of the first lens L1, the object-side surface S5 of the third lens S3, the object-side surface S7 and the image-side surface S8 of the fourth lens L4, and the object-side surface S11 and the image-side surface S12 of the sixth lens L6 are spherical.

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 glass.

Further, the optical system 100 satisfies the conditional expression: (d 12/f) = 100.055; where d12 is a distance on the optical axis 110 from the image-side surface S2 of the first lens element L1 to the object-side surface S3 of the second lens element L2, and f is an effective focal length of the optical system 100. When the above conditional expressions are satisfied, the air space between the first lens L1 and the second lens L2 and the effective focal length of the optical system 100 can be configured reasonably, which is favorable for the optical system 100 to have the telephoto characteristic, and is favorable for correcting the aberration of the optical system 100, thereby taking into account the realization of the telephoto characteristic and the high imaging quality, and in addition, is favorable for making the structure of the optical system 100 more compact, thereby being favorable for realizing the miniaturized design.

The optical system 100 satisfies the conditional expression: f1/f =10.103; where f1 is the effective focal length of the first lens L1. When the above conditional expressions are satisfied, the refractive power ratio of the first lens element L1 in the optical system 100 can be configured reasonably, so that the aberration of the optical system 100 can be corrected, and the imaging resolution of the optical system 100 can be improved.

The optical system 100 satisfies the conditional expression: f4/CT4=2.146; where f4 is an effective focal length of the fourth lens element L4, and CT4 is a thickness of the fourth lens element L4 on the optical axis 110. When the conditional expressions are satisfied, the ratio of the effective focal length to the center thickness of the fourth lens L4 can be reasonably configured, which is beneficial to reducing the tolerance sensitivity of the center thickness of the fourth lens L4, thereby being beneficial to reducing the difficulty of the processing technology of the fourth lens L4, further being beneficial to improving the assembly yield of the optical system 100 and reducing the production cost; while also advantageously reducing the overall length of the optical system 100.

The optical system 100 satisfies the conditional expression: f5 f6/f = -10.144mm; where f5 is an effective focal length of the fifth lens L5, and f6 is an effective focal length of the sixth lens L6. When the above conditional expressions are satisfied, the refractive power ratio of the fifth lens element L5 and the sixth lens element L6 in the optical system 100 can be reasonably configured, so that the positive refractive power of the fifth lens element L5 and the negative refractive power of the sixth lens element L6 can be effectively matched, and further the total length of the optical system 100 is shortened while the aberration of the fifth lens element L5 and the aberration of the sixth lens element L6 can be effectively corrected, thereby improving the imaging quality of the optical system 100.

The optical system 100 satisfies the conditional expression: TTL/f =1.839; 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. When the above conditional expressions are satisfied, the ratio of the total optical length to the effective focal length of the optical system 100 can be configured reasonably, which is favorable for realizing the miniaturization design of the optical system 100, and is also favorable for realizing the long-focus characteristic and possessing a reasonable field angle range of the optical system 100, so that sufficient object space information can be acquired.

The optical system 100 satisfies the conditional expression: CT6/SAG62=2.959; where CT6 is the thickness of the sixth lens L6 on the optical axis 110, and SAG62 is the rise of the sixth lens L6 at the maximum effective aperture of the image-side surface S12. When the above conditional expressions are satisfied, the ratio of the center thickness of the sixth lens L6 to the rise of the image-side surface S12 can be reasonably configured, so that the center thickness of the sixth lens L6 is not too large, and the surface shape of the image-side surface S12 of the sixth lens L6 is not too curved, which is beneficial to reducing the tolerance sensitivity of the sixth lens L6 and improving the forming yield of the sixth lens L6.

The optical system 100 satisfies the conditional expression: imgH 2/f =0.630; here, imgH is half the image height corresponding to the maximum field angle of the optical system 100. When the conditional expression is satisfied, the ratio of the half-image height to the effective focal length of the optical system 100 can be reasonably configured, so that the distortion of the optical system 100 can be corrected while the long-focus characteristic is realized, and the imaging quality of the optical system 100 is improved; in addition, the optical system 100 is also beneficial to matching with a photosensitive element with a larger size, so that the optical system 100 has high pixels, and the imaging quality of the optical system 100 is improved.

The optical system 100 satisfies the conditional expression: vd2=82.5; vd3=24.8; wherein Vd2 is the abbe number of the second lens L2 at the wavelength of 587.56nm, and Vd3 is the abbe number of the third lens L3 at the wavelength of 587.56 nm. Satisfying the above conditional expressions is beneficial to better correcting chromatic aberration of the optical system 100 and improving imaging quality of the optical system 100.

In addition, the parameters of the optical system 100 are given in table 1. Here, the image plane S17 in table 1 may be understood as an imaging plane of the optical system 100. Elements from the object plane (not shown) to the image plane S17 are sequentially arranged in the order of 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. The surface number S1 and the surface number S2 are 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 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 value is the distance from the image-side surface to the rear surface along the image-side direction of the lens element along the optical axis 110.

It should be noted that in this embodiment and the following embodiments, the optical system 100 may not be provided with the infrared filter L7 and the protective glass L8, but the distance between the lenses and the distance from the image side surface S12 of the sixth lens L6 to the image surface S17 are kept constant.

In the first embodiment, the effective focal length f =16.32mm, the f-number FNO =1.65, and the maximum field angle FOV =35.6 ° of the optical system 100.

The reference wavelength of the focal length of each lens is 546.074nm, the reference wavelengths of the refractive index and the Abbe number are 587.56nm, and the same is true for other embodiments.

TABLE 1

Further, aspheric coefficients of the image side or the object side of the lens provided with the aspheric optical system 100 are given by table 2. The surface numbers S1, S3, S4, S9, and S10 respectively denote an object side surface S1, an object side surface S3, an image side surface S4, an object side surface S9, and an image side surface S10. And K-a20 from top to bottom respectively represent the 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 octa 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

Noodle sequence number	S1	S3	S4	S9	S10
						K	-3.669E-01	6.665E-03	3.006E+01	2.089E-01	-3.842E+00
A4	-9.299E-06	-2.484E-06	-4.924E-04	3.641E-07	4.254E-05
						A6	-7.029E-07	6.980E-07	-5.526E-07	5.509E-07	1.952E-07
A8	-2.880E-09	2.804E-08	-6.904E-07	-5.978E-09	-6.102E-09
						A10	-7.265E-10	4.638E-10	5.296E-09	4.570E-10	5.516E-11
A12	-2.673E-12	-8.095E-11	-8.256E-11	-9.523E-12	-1.009E-12
						A14	0.000E+00	0.000E+00	0.000E+00	0.000E+00	0.000E+00
A16	0.000E+00	0.000E+00	0.000E+00	0.000E+00	0.000E+00
						A18	0.000E+00	0.000E+00	0.000E+00	0.000E+00	0.000E+00
A20	0.000E+00	0.000E+00	0.000E+00	0.000E+00	0.000E+00

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 spots or color halos in the imaging picture are effectively inhibited. FIG. 2 also includes a FIELD curvature diagram (ASTIMATIC FIELD CURVES) of the optical system 100, where the S-curve represents sagittal FIELD curvature at 546.074nm and the T-curve represents meridional FIELD curvature at 546.074nm. 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, which shows 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 first lens element L1 with positive refractive power, a second lens element L2 with positive refractive power, a stop STO, an ir-filter L7, 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 negative refractive power, and a protective glass L8, and the third lens element L3 is cemented with the fourth lens element L4. Fig. 4 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the second embodiment, which is sequentially from left to right, wherein the reference wavelength of the astigmatism diagram and the distortion diagram is 546.074nm.

The object-side surface S1 of the first lens L1, the image-side surface S4 of the second lens L2, and the object-side surface S9 and the image-side surface S10 of the fifth lens L5 are aspheric, and the object-side surface S2 of the first lens L1, the object-side surface S3 of the second lens L2, the object-side surface S5 of the third lens S3, the object-side surface S7 and the image-side surface S8 of the fourth lens L4, and the object-side surface S11 and the image-side surface S12 of the sixth lens L6 are spherical.

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

Number of noodles	S1	S4	S9	S10
					K	0.000E+00	0.000E+00	2.089E-02	-3.842E+00
A4	-5.994E-06	-8.200E-04	3.641E-07	2.543E-05
					A6	-4.290E-07	-5.773E-06	5.509E-07	1.952E-07
A8	-2.880E-09	-1.007E-07	-5.978E-09	-6.102E-09
					A10	-7.265E-10	5.066E-09	4.570E-10	9.752E-11
A12	-2.673E-12	6.714E-13	-9.523E-12	-1.009E-12
					A14	0.000E+00	0.000E+00	0.000E+00	0.000E+00
A16	0.000E+00	0.000E+00	0.000E+00	0.000E+00
					A18	0.000E+00	0.000E+00	0.000E+00	0.000E+00
A20	0.000E+00	0.000E+00	0.000E+00	0.000E+00

According to the provided parameter information, the following data can be deduced:

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 first lens element L1 with positive refractive power, a stop STO, 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 positive refractive power, a sixth lens element L6 with negative refractive power, an ir-filter L7, and a protective glass L8, wherein the second lens element L2 is cemented with the third lens element L3, and the fifth lens element L5 is cemented with the sixth lens element L6. Fig. 6 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the third embodiment, which is sequentially from left to right, wherein the reference wavelength of the astigmatism graph and the distortion graph is 550nm.

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 S9 of the fifth lens element L5 is convex at the paraxial region 110, and the image-side surface S10 is concave 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 S1 and the image-side surface S2 of the first lens L1, the object-side surface S7 and the image-side surface S78 of the fourth lens L4 are aspheric, and the object-side surface S3 of the second lens L2, the object-side surface S5 and the image-side surface S6 of the third lens S3, the object-side surface S9 of the fifth lens L5, and the object-side surface S11 and the image-side surface S12 of the sixth lens L6 are spherical.

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

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

Number of noodles	S1	S2	S7	S8
					K	4.018E-01	4.094E+00	-4.644E+01	-4.069E-01
A4	-2.903E-07	-4.633E-05	-4.230E-05	-7.096E-06
					A6	1.510E-07	2.165E-06	-3.764E-06	-7.075E-07
A8	5.240E-08	-1.470E-07	5.493E-08	-4.270E-09
					A10	-8.017E-10	4.966E-09	-7.458E-10	8.028E-11
A12	1.332E-11	-3.254E-11	3.401E-12	-1.626E-12
					A14	0.000E+00	0.000E+00	0.000E+00	0.000E+00
A16	0.000E+00	0.000E+00	0.000E+00	0.000E+00
					A18	0.000E+00	0.000E+00	0.000E+00	0.000E+00
A20	0.000E+00	0.000E+00	0.000E+00	0.000E+00

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

(d12/f)*100	20.880	TTL/f	1.950
				f1/f	3.618	CT6/SAG62	0.420
f4/CT4	6.179	ImgH*2/f	0.628
				f5*f6/f(mm)	-19.096

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, and the optical system 100 includes, in order from an object side to an image side, a first lens element L1 with positive refractive power, a stop STO, 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 positive refractive power, a sixth lens element L6 with negative refractive power, an ir-filter L7 and a protective glass L8, where the second lens element L2 is cemented with the third lens element L3 and the fifth lens element L5 is cemented with the sixth lens element L6. Fig. 8 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the fourth embodiment, which is sequentially from left to right, wherein the reference wavelength of the astigmatism graph and the distortion graph is 550nm.

The object-side surface S1 and the image-side surface S2 of the first lens L1, the object-side surface S7 and the image-side surface S8 of the fourth lens L4 are aspheric, and the object-side surface S3 of the second lens L2, the object-side surface S5 and the image-side surface S6 of the third lens S3, the object-side surface S9 of the fifth lens L5, and the object-side surface S11 and the image-side surface S12 of the sixth lens L6 are spherical.

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

TABLE 8

Number of noodles	S1	S2	S7	S8
					K	3.541E-01	8.948E+00	-7.989E+01	-1.785E-01
A4	5.232E-07	-8.193E-04	-3.022E-05	-8.368E-05
					A6	-2.003E-07	-1.239E-06	-2.891E-06	-2.277E-06
A8	7.962E-08	-1.752E-07	5.032E-08	7.896E-08
					A10	-5.776E-09	4.089E-09	-1.395E-09	-1.749E-09
A12	8.339E-11	-1.433E-10	1.257E-11	1.915E-11
					A14	0.000E+00	0.000E+00	0.000E+00	0.000E+00
A16	0.000E+00	0.000E+00	0.000E+00	0.000E+00
					A18	0.000E+00	0.000E+00	0.000E+00	0.000E+00
A20	0.000E+00	0.000E+00	0.000E+00	0.000E+00

(d12/f)*100	22.475	TTL/f	1.841
				f1/f	2.796	CT6/SAG62	0.416
f4/CT4	9.689	ImgH*2/f	0.633
				f5*f6/f(mm)	-19.711

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, and the optical system 100 includes, in order from an object side to an image side, a first lens element L1 with positive refractive power, a second lens element L2 with positive refractive power, a stop STO, 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 negative refractive power, an ir-filter L7 and a protective glass L8, where the third lens element L3 is cemented with the fourth lens element L4. Fig. 10 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the fifth embodiment, which are sequentially from left to right, wherein the reference wavelength of the astigmatism diagram and the distortion diagram is 546.074nm.

The object-side surface S1 and the image-side surface S2 of the first lens L1, the object-side surface S9 and the image-side surface S10 of the fifth lens L5 are aspheric, and the object-side surface S3 and the image-side surface S4 of the second lens L2, the object-side surface S5 of the third lens S3, the object-side surface S7 and the image-side surface S8 of the fourth lens L4, and the object-side surface S11 and the image-side surface S12 of the sixth lens L6 are spherical.

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 derived from the first embodiment, which is not repeated herein.

Watch 10

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

(d12/f)*100	14.442	TTL/f	1.845
				f1/f	1.685	CT6/SAG62	4.660
f4/CT4	1.961	ImgH*2/f	0.634
				f5*f6/f(mm)	-5.736

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 can be regarded as the image surface S17 of the optical system 100. 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 can achieve both the long-focus characteristic and the high imaging quality, and is also beneficial to realizing the miniaturization design.

Referring to fig. 11 and 12, in some embodiments, the image capturing module 200 may be applied to an electronic device 300, which includes a housing 310, and the image capturing module 200 is disposed in the housing 310. Specifically, the electronic device 300 may be, but is not limited to, a wearable device such as a portable phone, a video phone, a smart phone, an electronic book reader, or a smart watch. By adopting the image capturing module 200 in the electronic device 300, the realization of both the long focus characteristic and the high imaging quality can be achieved, and the miniaturization design can be realized.

More specifically, in some embodiments, the electronic apparatus 300 is an onboard device such as a vehicle event recorder, and the electronic apparatus 300 may be used for onboard forward looking camera shooting. The optical system 100 is applied to the vehicle-mounted front camera, and the optical system 100 has a long-focus characteristic, so that the influence of a long distance can be observed, and a driver can know the road condition ahead in real time in the driving process. Meanwhile, the optical system 100 has good imaging quality while realizing the telephoto characteristic, and can further improve the driving safety.

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 specific and detailed, but not to be understood 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 is a fixed focus system, wherein the optical system includes six lenses having refractive power, and the optical system sequentially includes, 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 a paraxial region and a concave image-side surface at a paraxial region;

a third lens element with refractive power;

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

and the optical system satisfies the following conditional expression:

10≤(d12/f)*100≤22.5；

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

1.5≤f1/f≤10.2；

wherein f1 is an effective focal length of the first lens.

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

1.9≤f4/CT4≤10；

wherein f4 is an effective focal length of the fourth lens element, and CT4 is a thickness of the fourth lens element on the optical axis.

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

-20mm≤f5*f6/f≤-5.5mm；

wherein f5 is an effective focal length of the fifth lens, and f6 is an effective focal length of the sixth lens.

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

1.8≤TTL/f≤2.3；

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.

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

0.4≤CT6/SAG62≤5；

wherein CT6 is the thickness of the sixth lens on the optical axis, and SAG62 is the rise of the sixth lens at the maximum effective aperture of the image side surface.

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

0.6≤ImgH*2/f≤1；

wherein ImgH is half of the image height corresponding to the maximum field angle of the optical system.

8. The optical system according to any one of claims 1 to 7, further comprising an infrared filter disposed between the second lens and the third lens.

9. An image capturing module, comprising a photosensitive element and the optical system of any one of claims 1 to 8, wherein the photosensitive element is disposed on an image side of the optical system.

10. An electronic device, comprising a housing and the image capturing module of claim 9, wherein the image capturing module is disposed on the housing.