CN112799211B

CN112799211B - Optical system, image capturing module and electronic equipment

Info

Publication number: CN112799211B
Application number: CN202110050583.9A
Authority: CN
Inventors: 刘彬彬; 党绪文; 李明; 邹海荣
Original assignee: Jiangxi Jingchao Optical Co Ltd
Current assignee: Jiangxi Jingchao Optical Co Ltd
Priority date: 2021-01-14
Filing date: 2021-01-14
Publication date: 2022-06-24
Anticipated expiration: 2041-01-14
Also published as: CN112799211A

Abstract

The invention relates to an optical system, an image capturing module and an electronic device. The optical system includes: a first lens element with positive refractive power having a convex object-side surface and a convex image-side surface; a second lens element with refractive power having a convex object-side surface at paraxial region; a third lens element with negative refractive power having a concave image-side surface at paraxial region; the object side surface and the image side surface of the fourth lens element with positive refractive power are aspheric surfaces; the fifth lens element with refractive power has an object-side surface and an image-side surface which are both aspheric, and at least one of the object-side surface and the image-side surface has an inflection point; the optical system satisfies the conditional expression: 105.0 to (43/IMGH) f to 120.0. The optical system can realize a telephoto characteristic.

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

The human eye has ultrahigh response speed and resolution for imaging a limited-distance object, but is very difficult to clearly see a long-distance object, and the optical system with the long-focus characteristic has good telephoto performance and can shoot a long-distance shot object. Therefore, an optical system having a telephoto characteristic is an important means for extending a visible distance of human eyes, and the application of the telephoto optical system in electronic devices is becoming wider and wider. However, the conventional optical system has insufficient effective focal length and is difficult to have good telephoto performance.

Disclosure of Invention

Accordingly, there is a need for an optical system, an image capturing module and an electronic device to achieve a long-focus characteristic.

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

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

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

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

the fourth lens element with positive refractive power has an object-side surface and an image-side surface which are both aspheric;

the fifth lens element with refractive power has an object-side surface and an image-side surface which are both aspheric;

and the optical system satisfies the following conditional expression:

105.0≤(43/IMGH)*f≤120.0；

the IMGH is an image height corresponding to a maximum field angle of the optical system, that is, a diameter of a maximum effective imaging circle of the optical system, and f is an effective focal length of the optical system.

In the optical system, the first lens element has positive refractive power, which is beneficial to shortening the total length of the optical system. The object-side surface and the image-side surface of the first lens element are convex at paraxial region, which is favorable for enhancing the positive refractive power of the first lens element and further shortening the total length of the optical system, thereby being favorable for the miniaturization design of the optical system. The object side surface and the image side surface of the fourth lens and the fifth lens are both aspheric surfaces, so that the flexibility of lens design is improved, the spherical aberration of the optical system is effectively corrected, and the imaging quality of the optical system is improved.

The above conditional expression converts the effective focal length of the optical system into the equivalent focal length with reference to a 35mm standard lens. When the lower limit of the conditional expression is satisfied, the equivalent focal length of the optical system exceeds 100mm, so that the optical system can have strong telephoto characteristics and realize a good telephoto effect.

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

2.5≤f/IMGH≤2.7；

when the condition formula is met, the optical system does not improve the magnification by sacrificing the characteristic of a large image plane, and when the upper limit of the condition formula is met, the optical system has a large image plane and can be matched with large-size photosensitive chips, for example, the optical system can be adapted to most of 32M and 48M photosensitive chips in the market, so that the imaging quality of the optical system is improved, and meanwhile, the optical system has good universality and applicability. In summary, the optical system has a large image plane characteristic while realizing a telephoto characteristic, and can achieve both the telephoto characteristic and good image quality.

0.4≤OAL/BF≤0.7；

wherein OAL is a distance on an optical axis from an object-side surface of the first lens element to an image-side surface of the fifth lens element, and BF is a shortest distance in the optical axis direction from the image-side surface of the fifth lens element to an image plane of the optical system. BF is an important index for matching between an optical system and a photosensitive element and for structural design of a module, and the longer BF, the higher flexibility for designing and manufacturing the module. When the above conditional expressions are satisfied, the optical system has a long back-focus characteristic, and can more easily match a prism or a reflection system having a refraction effect to reduce the overall occupied space of the optical system, thereby facilitating the miniaturization design of the optical system 100; in addition, the optical system is beneficial to ensuring that each lens in the optical system has enough thickness and clearance, and five lenses can be mutually matched, so that the structure is compact, and the miniaturization design of the optical system is facilitated while good imaging quality is realized. If the lower limit of the above conditional expression is lower, the design of the telephoto structure of the optical system is difficult, and the lens surface shape is easily distorted excessively, which affects the molding and manufacturing of the lens. If the upper limit of the above conditional expression is exceeded, the gap between the lenses in the optical system becomes too large, the back focal length of the optical system is compressed, and the miniaturization of the optical system is not facilitated when the telephoto characteristic is realized

In one embodiment, the optical system further includes an aperture stop disposed on an object side of the third lens, and the optical system satisfies the following conditional expression:

2.0≤FNO≤2.55；

7.0mm≤|f5|/FNO≤24.0mm；

where f5 is an effective focal length of the fifth lens, and FNO is an f-number of the optical system. When the conditional expression is met, the two distribution schemes of the aperture diaphragm can be matched with the refractive power configuration of the fifth lens, so that the compactness of the optical system structure is realized, and the miniaturization design of the optical system is facilitated; meanwhile, the optical system can obtain enough light entering amount, the diffraction limit of the optical system is increased, the resolution of the optical system is improved, the attenuation of the resolution from the center to the edge of a view field is reduced, and the relative brightness of the full view field is improved; in addition, the optical system can be provided with a large aperture characteristic while realizing a telephoto characteristic.

R32/|R41|≤0.7；

wherein R32 is a curvature radius of an image side surface of the third lens at an optical axis, and R41 is a curvature radius of an object side surface of the fourth lens at the optical axis. When the conditional expressions are satisfied, the surface types of the image side surface of the third lens and the object side surface of the fourth lens can be better matched with each other, thereby being beneficial to reducing the rise change of the image side surface of the third lens and the object side surface of the fourth lens, also being beneficial to reducing the vignetting coefficient of an optical system, and simultaneously realizing the effect of compact gap between the third lens and the fourth lens. Meanwhile, the curvature radius of the image side surface of the third lens at the optical axis is positive, so that when the conditional expressions are satisfied, the light rays contracted by each lens at the object side of the third lens are favorably diffused properly, the fourth lens and the fifth lens are better matched with the guidance of the external view field light rays, the complexity of the surface type of the fourth lens and the complexity of the surface type of the fifth lens are favorably reduced, and the reliability of the lens forming and manufacturing are improved. In addition, the fourth lens element has positive refractive power, and when the conditional expressions are satisfied, the design flexibility of the optical system is improved while the compact structure is realized, so that the maximum incident angle of the incident image plane is easier to match with the photosensitive element, and meanwhile, the fourth lens element and the fifth lens element can also reserve enough space for the focusing and module mechanism of the optical system.

f12＞0；

f45＞0；

0.8≤f12/f45≤1.4；

wherein f12 is a combined focal length of the first lens and the second lens, and f45 is a combined focal length of the fourth lens and the fifth lens. The first lens element and the second lens element as a whole, and the fourth lens element and the fifth lens element as a whole have positive refractive power, and can form a positive-negative-positive Cuck-like three-piece structure in cooperation with the negative refractive power of the third lens element, and when the above conditional expressions are satisfied, the ratio of f12 to f45 can be reasonably configured, and in cooperation with the surface shape and the reasonable distribution of the structure of each lens element of the optical system, the optical system can have a long-focus characteristic while achieving a compact structure, and the surface shape of each lens element can be smoother. Meanwhile, various off-axis aberrations of the optical system, such as distortion, field curvature, astigmatism and the like, can be corrected, and good imaging quality can be obtained.

f12＞0；

f45＞0；

CT45≤0.6；

0.6≤(CT12+CT34+CT45)/CT5≤3.1；

wherein, CT12 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, CT34 is a distance on the optical axis from the image-side surface of the third lens element to an object-side surface of the fourth lens element, CT45 is a distance on the optical axis from the image-side surface of the fourth lens element to an object-side surface of the fifth lens element, and CT5 is a thickness on the optical axis of the fifth lens element, that is, a center thickness of the fifth lens element. When the condition formula is satisfied, the method is favorable for improving the matching degree of each lens surface type and improving the compactness of the optical system structure, thereby being favorable for shortening the total length of the optical system. In addition, under the reasonable refractive power configuration, a smaller gap is formed between the fourth lens element and the fifth lens element when the conditional expressions are satisfied, so that the fourth lens element and the fifth lens element are similar to a cemented lens element, the compactness of the structure between the fourth lens element and the fifth lens element is improved, and the improvement of the chromatic aberration correction effect of the fourth lens element and the fifth lens element is facilitated. Meanwhile, the structure matching of the lenses can be compact, the gap space between the lenses can be compressed, the change of the surface shape of each lens tends to be smooth, and the generation of stray light of an optical system is reduced.

f1≤10.5mm；

0.8≤|f2|/|R22|≤8.0；

wherein f2 is an effective focal length of the second lens, and R22 is a radius of curvature of an image side surface of the second lens at an optical axis. The positive refractive power of the first lens element is stronger, so that the second lens element can narrow light and restrain the deflection angle of light without stronger refractive power, and the second lens element can have positive or negative refractive power. Meanwhile, when the conditional expressions are satisfied, the refractive power strength of the second lens element and the image side surface shape at the paraxial position can be well configured, so that the matching relation between the second lens element and the first lens element and the third lens element can be improved, the surface shape and thickness design change of the second lens element is more flexible, and the flexibility of design can be increased for the optical system; in addition, the total length of the optical system is reduced, and the tolerance sensitivity of the optical system is reduced.

In one embodiment, the optical system further includes an aperture stop disposed on an object-side surface of the first lens or between the second lens and the third lens, and the optical system satisfies the following conditional expression:

0.50≤SD11/IMGH≤0.7；

wherein SD11 is half of the maximum effective aperture of the object side surface of the first lens. The telephoto characteristic of a general optical system is matched with the large aperture design, so that the size of the entrance pupil diameter of the optical system is equal to or larger than that of the image plane, and two compact structures of rapidly reducing the effective aperture of each lens and slowly reducing the effective aperture of each lens are realized by two distribution schemes of the aperture diaphragm. Satisfying above-mentioned conditional expression, can carrying out rational configuration to half of the maximum effective bore of the object side of first lens and optical system's half image height's ratio for above-mentioned two kinds of distribution schemes of aperture diaphragm can both obtain good structural layout, reduce optical system structural design's the degree of difficulty.

1.0≤SD11/SD52≤1.6；

wherein SD52 is half of the maximum effective aperture of the image-side surface of the fifth lens element. When the conditional expression is satisfied, the two distribution schemes of the aperture diaphragm can both obtain good structural layout, and the difficulty of structural design of the optical system is reduced. Meanwhile, the effective calibers of the lenses of the optical system can be reasonably changed, the design of the bearing structure of the lenses is convenient, and the manufacturability of the optical system is improved.

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 image capturing module adopts the optical system, can realize the long-focus characteristic and has good telephoto performance.

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 realize the long focal characteristic, possess good telephoto performance.

Drawings

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

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

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

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

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

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

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

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

FIG. 9 is a schematic 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 structural diagram of an optical system according to a sixth embodiment of the present application;

FIG. 12 is a longitudinal 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 structural diagram of an optical system according to a seventh embodiment of the present application;

FIG. 14 is a longitudinal spherical aberration diagram, an astigmatism diagram and a distortion diagram of an optical system in a seventh embodiment of the present application;

fig. 15 is a schematic view of an image capturing module according to an embodiment of the present application;

fig. 16 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 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.

In some embodiments of the present application, 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 and a fifth lens L5. 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, and the fifth lens element L5 includes an object-side surface S9 and an image-side surface S10.

The first lens element L1 with positive refractive power is advantageous for shortening the total length of the optical system 100. The object-side surface S1 and the image-side surface S2 of the first lens element L1 are both convex at the paraxial region 110, which is favorable for enhancing the positive refractive power of the first lens element L1 and further shortening the total length of the optical system 100, thereby being favorable for the miniaturization design of the optical system 100. The second lens element L2 with refractive power has a convex object-side surface S3 at a paraxial region 110 of the second lens element L2. The third lens element L3 with negative refractive power has a concave image-side surface S6 at the paraxial region 110 of the third lens element L3. The fourth lens element L4 has positive refractive power, and the fifth lens element L5 has refractive power. The object-side surface and the image-side surface of the fourth lens element L4 and the fifth lens element L5 are aspheric, which is beneficial to improving the flexibility of lens design, effectively correcting the spherical aberration of the optical system 100, and improving the imaging quality of the optical system. In some embodiments, at least one of the object-side surface S9 and the image-side surface S10 of the fifth lens element L5 has an inflection point, which is favorable for correcting the aberration of the peripheral field of view of the optical system 100, and further improves the imaging quality of the optical system 100.

In addition, in some embodiments, the optical system 100 is provided with an aperture stop STO, which may be disposed on the object side of the third lens L3. Specifically, in some examples, the stop STO is on the object side of the first lens L1, or is disposed between the second lens L2 and the third lens L3. In some embodiments, the optical system 100 further includes an infrared filter L6 disposed on the image side of the fifth lens L5, and the infrared filter L6 includes an object-side surface S11 and an image-side surface S12. Furthermore, the optical system 100 further includes an image surface S13 located on the image side of the fifth lens L5, the image surface S13 is an imaging surface of the optical system 100, and incident light is adjusted by the first lens L1, the second lens L2, the third lens L3, the fourth lens L4 and the fifth lens L5 and can be imaged on the image surface S13. It should be noted that the infrared filter L6 may be an infrared cut filter, and is used for filtering the interference light and preventing the interference light from reaching the image plane S13 of the optical system 100 to affect the normal imaging.

In some embodiments, the object-side surface and the image-side surface of each lens of optical system 100 are both aspheric. The adoption of the aspheric surface structure can improve the flexibility of lens design, effectively correct spherical aberration and improve imaging quality. In other embodiments, besides the fourth lens L4 and the fifth lens L5, both 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 light and thin design of the optical system can be realized by matching with the smaller size 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 or the fifth lens L5 in some embodiments may also be greater than or equal to two, and a cemented lens may be formed between any two adjacent lenses, or may also be a non-cemented lens.

Further, in some embodiments, the optical system 100 satisfies the conditional expression: 105.0 to (43/IMGH) f to 120.0; where IMGH is the image height corresponding to the maximum field angle of the optical system 100, i.e. the diameter of the maximum effective imaging circle of the optical system 100, and f is the effective focal length of the optical system 100. Specifically, (43/IMGH) × f may be: 109.32, 109.65, 110.20, 111.64, 112.36, 113.85, 114.15, 115.36, 115.98, or 116.36. The above conditional expression converts the effective focal length of the optical system 100 into the equivalent focal length with reference to a 35mm standard lens. When the lower limit of the above conditional expression is satisfied, the equivalent focal length of the optical system 100 exceeds 100mm, and thus a strong telephoto characteristic can be possessed, and a good telephoto effect can be achieved.

In some embodiments, the optical system 100 satisfies the conditional expression: f/IMGH is more than or equal to 5 and less than or equal to 2.7. Specifically, f/IMGH may be: 2.54, 2.55, 2.56, 2.58, 2.59, 2.61, 2.63, 2.66, 2.67, or 2.70. When the condition is satisfied, the optical system 100 does not increase the magnification by sacrificing the large image plane characteristic, and when the upper limit of the condition is satisfied, the optical system 100 has a large image plane and can be matched with a large-sized photosensitive chip, for example, the optical system 100 can be adapted to most of 32M and 48M photosensitive chips in the market, so as to increase the imaging quality of the optical system 100, and meanwhile, the optical system 100 has good universality and applicability. As described above, the optical system 100 has a large image plane characteristic while realizing a telephoto characteristic, and can achieve both the telephoto characteristic and good image quality.

In some embodiments, the optical system 100 satisfies the conditional expression: OAL/BF is more than or equal to 0.4 and less than or equal to 0.7; here, OAL is a distance from the object-side surface S1 of the first lens element L1 to the image-side surface S10 of the fifth lens element L5 on the optical axis 110, and BF is a shortest distance from the image-side surface S10 of the fifth lens element L5 to the image plane of the optical system 100 on the optical axis 110. Specifically, OAL/BF may be: 0.45, 0.47, 0.49, 0.50, 0.51, 0.52, 0.56, 0.57, 0.59, or 0.67. BF is an important index for matching between the optical system 100 and the photosensitive device and for designing the module structure, and the longer BF, the higher flexibility for designing and manufacturing the module. When the above conditional expressions are satisfied, the optical system 100 has a long back-focus characteristic, and the prism or the reflection system having the refraction effect can be more easily matched to reduce the overall occupied space of the optical system 100, thereby facilitating the miniaturization design of the optical system 100; in addition, it is also beneficial to ensure sufficient thickness and clearance of each lens in the optical system 100, and make five lenses capable of cooperating with each other, the structure is compact, and it is beneficial to realize miniaturization design of the optical system 100 while realizing good imaging quality. If the lower limit of the above conditional expression is lower, the design of the telephoto structure of the optical system 100 is difficult, and the lens surface shape is easily distorted excessively, which affects the molding and manufacturing of the lens. If the upper limit of the above conditional expression is exceeded, the gap between the lenses in the optical system 100 becomes too large, and the back focal length of the optical system 100 is compressed, which is disadvantageous for the compact design of the optical system 100 in realizing the telephoto characteristic.

In some embodiments, the optical system 100 satisfies the conditional expression: FNO is more than or equal to 2.0 and less than or equal to 2.55; the absolute value of f 5/FNO is more than or equal to 7.0mm and less than or equal to 24.0 mm; where f5 is an effective focal length of the fifth lens L5, and FNO is an f-number of the optical system 100. Specifically, | f5|/FNO may be: 7.10, 9.65, 11.22, 15.62, 17.35, 19.55, 20.05, 21.36, 22.87 or 23.32, with numerical units in mm. When the above conditional expressions are satisfied, the two distribution schemes of the aperture stop STO can be matched with the refractive power configuration of the fifth lens element L5, so that the compactness of the structure of the optical system 100 is realized, and the miniaturization design of the optical system 100 is facilitated. Meanwhile, the optical system 100 can obtain enough light input amount, the diffraction limit of the optical system 100 is increased, the resolution of the optical system 100 is improved, the attenuation of the resolution from the center to the edge of the field of view is reduced, and the relative brightness of the full field of view is improved; in addition, the optical system 100 can be provided with a large aperture characteristic while realizing a telephoto characteristic.

In some embodiments, the optical system 100 satisfies the conditional expression: r32/| R41| is less than or equal to 0.7; wherein, R32 is a curvature radius of the image-side surface S6 of the third lens element L3 on the optical axis 110, and R41 is a curvature radius of the object-side surface S7 of the fourth lens element L4 on the optical axis 110. Specifically, R32/| R41| may be: 0.12, 0.15, 0.21, 0.26, 0.37, 0.48, 0.55, 0.59, 0.61 or 0.70. When the above conditional expressions are satisfied, the surface shapes of the image-side surface S6 of the third lens L3 and the object-side surface S7 of the fourth lens L4 can be matched with each other better, which is advantageous for reducing the sagitta change of the image-side surface S6 of the third lens L3 and the object-side surface S7 of the fourth lens L4, and also advantageous for reducing the vignetting coefficient of the optical system 100, and an effect of making the gap between the third lens L3 and the fourth lens L4 compact can be achieved. Meanwhile, the curvature radius of the image-side surface S6 of the third lens element L3 at the optical axis 110 is positive, so that when the above conditional expressions are satisfied, the light rays converging through each lens element at the object side of the third lens element L3 can be properly diffused, so as to better match the guidance of the external field of view light rays by the fourth lens element L4 and the fifth lens element L5, and at the same time, the complexity of the surface type of the fourth lens element L4 and the fifth lens element L5 can be reduced, and the reliability of the lens element molding manufacturing can be improved. In addition, the fourth lens element L4 has positive refractive power, and when the above conditional expressions are satisfied, the compact structure is achieved, and the flexibility of the optical system 100 design is improved, so that the maximum incident angle of the incident image plane is easier to match with the photosensitive element, and meanwhile, the fourth lens element L4 and the fifth lens element L5 can also reserve a sufficient distance for the focusing and module mechanism of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: f12 > 0; f45 > 0; f12/f45 is more than or equal to 0.8 and less than or equal to 1.4; wherein f12 is the combined focal length of the first lens L1 and the second lens L2, and f45 is the combined focal length of the fourth lens L4 and the fifth lens L5. Specifically, f12/f45 may be: 0.74, 0.76, 0.78, 0.82, 0.89, 1.03, 1.09, 1.21, 1.26 or 1.33. The whole of the first lens element L1 and the second lens element L2 and the whole of the fourth lens element L4 and the fifth lens element L5 both have positive refractive power, and a positive-negative-positive couck-like three-piece structure can be formed by matching with the negative refractive power of the third lens element L3, so that when the above conditional expressions are satisfied, the ratio of f12 to f45 can be reasonably configured, and the optical system 100 can have a long-focus characteristic while achieving a compact structure and can also be beneficial to smoother surface shapes of the lens elements by matching with reasonable allocation of surface shapes and structures of the lens elements of the optical system 100. Meanwhile, various off-axis aberrations of the optical system 100, such as distortion, curvature of field, astigmatism, and the like, can be corrected advantageously, and good imaging quality can be obtained.

In some embodiments, the optical system 100 satisfies the conditional expression: f12 > 0; f45 > 0; CT45 is less than or equal to 0.6; 0.6 is less than or equal to (CT12+ CT34+ CT45)/CT5 is less than or equal to 3.1; the CT12 is a distance between the image-side surface S2 of the first lens element L1 and the object-side surface S3 of the second lens element L2 on the optical axis 110, the CT34 is a distance between the image-side surface S6 of the third lens element L3 and the object-side surface S7 of the fourth lens element L4 on the optical axis 110, the CT45 is a distance between the image-side surface S8 of the fourth lens element L4 and the object-side surface S9 of the fifth lens element L5 on the optical axis 110, and the CT5 is a thickness of the fifth lens element L5 on the optical axis 110. Specifically, (CT12+ CT34+ CT45)/CT5 may be: 0.67, 0.98, 1.25, 1.65, 1.74, 2.12, 2.65, 2.88, 2.94, or 3.06. When the above conditional expressions are satisfied, the improvement of the degree of matching of the lens surface types is facilitated, and the compactness of the structure of the optical system 100 is improved, thereby facilitating the shortening of the total length of the optical system 100. In addition, under a reasonable refractive power configuration, the above conditional expression is satisfied, and a small gap is formed between the fourth lens element L4 and the fifth lens element L5, so that the fourth lens element L4 and the fifth lens element L5 are similar to a cemented lens, which improves the compactness of the structure between the fourth lens element L4 and the fifth lens element L5, and is beneficial to improving the chromatic aberration correction effect of the fourth lens element L4 and the fifth lens element L5. Meanwhile, the structure matching of the lenses can be compact, and the gap space between the lenses can be compressed, so that the change of the surface shape of each lens tends to be smooth, and further, the generation of stray light of the optical system 100 can be reduced.

In some embodiments, the optical system 100 satisfies the conditional expression: the absolute value f 2/R22 is more than or equal to 0.8 and less than or equal to 8.0; where f2 is the effective focal length of the second lens element L2, and R22 is the radius of curvature of the image-side surface S4 of the second lens element L2 at the optical axis 110. Specifically, | f2|/| R22| may be: 0.81, 1.10, 1.56, 2.54, 3.28, 4.66, 4.86, 5.35, 6.02, or 7.93. The first lens element L1 has positive refractive power, so that the second lens element L2 can narrow light and suppress the deflection angle of light without having strong refractive power, and the second lens element L2 can have positive or negative refractive power, so that when the above conditional expressions are satisfied, the flexibility of the structure of the second lens element L2 is improved, and the surface shape of the second lens element L2 is smooth, thereby providing a spherical aberration contribution for the optical system 100 to compensate the spherical aberration overflow phenomenon generated by the first lens element L1. Meanwhile, when the above conditional expressions are satisfied, the refractive power strength of the second lens element L2 and the paraxial image-side surface shape can be well configured, so that the matching relationship between the second lens element L2 and the first lens element L1 and the third lens element L3 can be improved, the design changes of the surface shape and the thickness of the second lens element L2 are more flexible, and the design flexibility of the optical system 100 can be increased; in addition, it is advantageous to reduce the overall length of the optical system 100 while reducing the tolerance sensitivity of the optical system 100.

In some embodiments, the optical system 100 satisfies the conditional expression: SD11/IMGH is more than or equal to 0.50 and less than or equal to 0.7; SD11 is half the maximum effective aperture of the object-side surface S1 of the first lens L1. Specifically, SD11/IMGH may be: 0.51, 0.52, 0.53, 0.54, 0.55, 0.57, 0.59, 0.60, 0.62 or 0.66. The telephoto characteristic of the general optical system 100 is matched with the large aperture design, so that the size of the entrance pupil diameter of the optical system 100 is equal to or larger than that of the image plane S13, and two compact structures of rapidly reducing the effective aperture of each lens and slowly reducing the effective aperture of each lens are realized by two distribution schemes of the aperture stop STO. Satisfying the above conditional expressions, it is possible to reasonably configure the ratio of half the maximum effective aperture of the object-side surface S1 of the first lens L1 to the half-image height of the optical system 100, so that the two distribution schemes of the aperture stop STO can both obtain a good structural layout, and the difficulty of the structural design of the optical system 100 is reduced.

In some embodiments, the optical system 100 satisfies the conditional expression: SD11/SD52 is more than or equal to 1.0 and less than or equal to 1.6; here, SD11 is half of the maximum effective diameter of the object-side surface S1 of the first lens L1, and SD52 is half of the maximum effective diameter of the image-side surface S10 of the fifth lens L5. Specifically, SD11/SD52 may be: 1.12, 1.15, 1.19, 21.20, 1.23, 1.28, 1.35, 1.42, 1.46 or 1.55. When the above conditional expressions are satisfied, the two distribution schemes of the aperture stop STO can both obtain good structural layout, and the difficulty of the structural design of the optical system 100 is reduced. Meanwhile, the effective calibers of the lenses of the optical system 100 can be reasonably changed, the bearing structure of the lenses is convenient to design, and the manufacturability of the optical system 100 is improved.

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 the optical system 100 in the first embodiment, and the optical system 100 includes, in order from an object side to an image side, an aperture stop STO, a first lens element L1 with positive refractive power, a second lens element L2 with negative refractive power, a third lens element L3 with negative refractive power, a fourth lens element L4 with positive refractive power, and a fifth lens element L5 with negative refractive power. Fig. 2 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the first embodiment, which is sequentially from left to right, wherein the reference wavelength of the astigmatism graph and the distortion graph is 587nm, and the other embodiments are the same.

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

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

the object-side surface S3 of the second lens element L2 is convex at a paraxial region 110 and convex at a peripheral region;

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 S5 of the third lens element L3 is concave at a paraxial region 110 and concave at a peripheral region;

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

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

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

the object-side surface S9 of the fifth lens element L5 is concave at a paraxial region 110 and concave at a peripheral region;

the image-side surface S10 of the fifth lens element L5 is concave at the paraxial region 110 and concave at the periphery.

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, and the fifth lens L5 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 at 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 a convex shape at the center is firstly transited to a concave shape, and then becomes a convex shape near the maximum effective radius. Here, examples are made only to illustrate the relationship between the near-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 and the fifth lens L5 are all made of plastic.

Further, the optical system 100 satisfies the conditional expression: (43/IMGH) × f 111.18; where IMGH is the image height corresponding to the maximum field angle of the optical system 100, and f is the effective focal length of the optical system 100. The above conditional expression converts the effective focal length of the optical system 100 into the equivalent focal length with reference to a 35mm standard lens. When the above conditional expressions are satisfied, the equivalent focal length of the optical system 100 exceeds 100mm, and thus the optical system can have a strong telephoto characteristic and realize a good telephoto effect.

The optical system 100 satisfies the conditional expression: f/IMGH 2.58. When the condition is satisfied, the optical system 100 does not increase the magnification by sacrificing the large image plane characteristic, and when the upper limit of the condition is satisfied, the optical system 100 has a large image plane and can be matched with a large-sized photosensitive chip, for example, the optical system 100 can be adapted to most of 32M and 48M photosensitive chips in the market, so as to increase the imaging quality of the optical system 100, and meanwhile, the optical system 100 has good universality and applicability. As described above, the optical system 100 has a large image plane characteristic while realizing a telephoto characteristic, and can achieve both the telephoto characteristic and good image quality.

The optical system 100 satisfies the conditional expression: OAL/BF 0.65; here, OAL is a distance from the object-side surface S1 of the first lens element L1 to the image-side surface S10 of the fifth lens element L5 on the optical axis 110, and BF is a shortest distance from the image-side surface S10 of the fifth lens element L5 to the image plane of the optical system 100 on the optical axis 110. BF is an important index for matching between the optical system 100 and the photosensitive device and for designing the module structure, and the longer BF, the higher flexibility for designing and manufacturing the module. When the above conditional expressions are satisfied, the optical system 100 has a long back-focus characteristic, and the prism or the reflection system having the refraction effect can be more easily matched to reduce the overall occupied space of the optical system 100, thereby facilitating the miniaturization design of the optical system 100; in addition, it is also beneficial to ensure sufficient thickness and clearance of each lens in the optical system 100, and make five lenses capable of cooperating with each other, the structure is compact, and it is beneficial to realize miniaturization design of the optical system 100 while realizing good imaging quality. Meanwhile, the difficulty degree of the design of the telephoto structure of the optical system 100 is reduced, the surface shape of the lens is not excessively distorted, the gap between the lenses in the optical system 100 is not excessively large, and the miniaturization design of the optical system 100 is facilitated.

The optical system 100 satisfies the conditional expression: FNO is more than or equal to 2.0 and less than or equal to 2.55; l f5 l/FNO 8.88 mm; where f5 is an effective focal length of the fifth lens L5, and FNO is an f-number of the optical system 100. When the above conditional expressions are satisfied, the two distribution schemes of the aperture stop STO can be matched with the refractive power configuration of the fifth lens element L5, so that the compactness of the structure of the optical system 100 is realized, and the miniaturization design of the optical system 100 is facilitated. Meanwhile, the optical system 100 can obtain enough light entering amount, the diffraction limit of the optical system 100 is increased, the resolution of the optical system 100 is improved, the attenuation of the resolution from the center to the edge of the view field is reduced, and the relative brightness of the full view field is improved; in addition, the optical system 100 can be provided with a large aperture characteristic while realizing a telephoto characteristic.

The optical system 100 satisfies the conditional expression: r32/| R41| ═ 0.48; wherein, R32 is a curvature radius of the image-side surface S6 of the third lens element L3 on the optical axis 110, and R41 is a curvature radius of the object-side surface S7 of the fourth lens element L4 on the optical axis 110. When the above conditional expressions are satisfied, the surface shapes of the image-side surface S6 of the third lens L3 and the object-side surface S7 of the fourth lens L4 can be matched with each other better, which is advantageous for reducing the sagitta change of the image-side surface S6 of the third lens L3 and the object-side surface S7 of the fourth lens L4, and also advantageous for reducing the vignetting coefficient of the optical system 100, and an effect of making the gap between the third lens L3 and the fourth lens L4 compact can be achieved. Meanwhile, the curvature radius of the image-side surface S6 of the third lens element L3 at the optical axis 110 is positive, so that when the above conditional expressions are satisfied, the light rays converging through each lens element at the object side of the third lens element L3 can be properly diffused, so as to better match the guidance of the external field of view light rays by the fourth lens element L4 and the fifth lens element L5, and at the same time, the complexity of the surface type of the fourth lens element L4 and the fifth lens element L5 can be reduced, and the reliability of the lens element molding manufacturing can be improved. In addition, the fourth lens element L4 has positive refractive power, and when the above conditional expressions are satisfied, the compact structure is achieved, and the flexibility of the optical system 100 design is improved, so that the maximum incident angle of the incident image plane is easier to match with the photosensitive element, and meanwhile, the fourth lens element L4 and the fifth lens element L5 can also reserve a sufficient distance for the focusing and module mechanism of the optical system 100.

The optical system 100 satisfies the conditional expression: f12 > 0; f45 > 0; f12/f45 is 0.74; wherein f12 is the combined focal length of the first lens L1 and the second lens L2, and f45 is the combined focal length of the fourth lens L4 and the fifth lens L5. The whole of the first lens element L1 and the second lens element L2 and the whole of the fourth lens element L4 and the fifth lens element L5 both have positive refractive power, and a positive-negative-positive couck-like three-piece structure can be formed by matching with the negative refractive power of the third lens element L3, so that when the above conditional expressions are satisfied, the ratio of f12 to f45 can be reasonably configured, and the optical system 100 can have a long-focus characteristic while achieving a compact structure and can also be beneficial to smoother surface shapes of the lens elements by matching with reasonable allocation of surface shapes and structures of the lens elements of the optical system 100. Meanwhile, various off-axis aberrations of the optical system 100, such as distortion, curvature of field, astigmatism and the like, can be corrected, and good imaging quality can be obtained.

The optical system 100 satisfies the conditional expression: f12 > 0; f45 > 0; CT45 is less than or equal to 0.6; (CT12+ CT34+ CT45)/CT5 ═ 1.52; the CT12 is a distance between the image-side surface S2 of the first lens element L1 and the object-side surface S3 of the second lens element L2 on the optical axis 110, the CT34 is a distance between the image-side surface S6 of the third lens element L3 and the object-side surface S7 of the fourth lens element L4 on the optical axis 110, the CT45 is a distance between the image-side surface S8 of the fourth lens element L4 and the object-side surface S9 of the fifth lens element L5 on the optical axis 110, and the CT5 is a thickness of the fifth lens element L5 on the optical axis 110. When the above conditional expressions are satisfied, the improvement of the degree of matching of the lens surface types is facilitated, and the compactness of the structure of the optical system 100 is improved, thereby facilitating the shortening of the total length of the optical system 100. In addition, under a reasonable refractive power configuration, the above conditional expression is satisfied, and a small gap is formed between the fourth lens element L4 and the fifth lens element L5, so that the fourth lens element L4 and the fifth lens element L5 are similar to a cemented lens, which improves the compactness of the structure between the fourth lens element L4 and the fifth lens element L5, and is beneficial to improving the chromatic aberration correction effect of the fourth lens element L4 and the fifth lens element L5. Meanwhile, the structure matching of the lenses can be compact, and the gap space between the lenses can be compressed, so that the change of the surface shape of each lens tends to be smooth, and further, the generation of stray light of the optical system 100 can be reduced.

The optical system 100 satisfies the conditional expression: f1 is less than or equal to 10.5 mm; l f2 l/l R22 l 5.89; where f2 is the effective focal length of the second lens element L2, and R22 is the radius of curvature of the image-side surface S4 of the second lens element L2 at the optical axis 110. The first lens element L1 has positive refractive power, so that the second lens element L2 can narrow light and suppress the deflection angle of light without having strong refractive power, and the second lens element L2 can have positive or negative refractive power, so that when the above conditional expressions are satisfied, the flexibility of the structure of the second lens element L2 is improved, and the surface shape of the second lens element L2 is smooth, thereby providing a spherical aberration contribution for the optical system 100 to compensate the spherical aberration overflow phenomenon generated by the first lens element L1. Meanwhile, when the above conditional expressions are satisfied, the refractive power strength of the second lens element L2 and the paraxial image-side surface shape can be well configured, so that the matching relationship between the second lens element L2 and the first lens element L1 and the third lens element L3 can be improved, the design changes of the surface shape and the thickness of the second lens element L2 are more flexible, and the design flexibility of the optical system 100 can be increased; in addition, it is advantageous to reduce the overall length of the optical system 100 while reducing the tolerance sensitivity of the optical system 100.

The optical system 100 satisfies the conditional expression: SD11/IMGH is 0.52; SD11 is half the maximum effective aperture of the object-side surface S1 of the first lens L1. The telephoto characteristic of the general optical system 100 is matched with the large aperture design, so that the size of the entrance pupil diameter of the optical system 100 is equal to or larger than that of the image plane S13, and two compact structures of rapidly reducing the effective aperture of each lens and slowly reducing the effective aperture of each lens are realized by two distribution schemes of the aperture stop STO. Satisfying the above conditional expressions, it is possible to reasonably configure the ratio of half the maximum effective aperture of the object-side surface S1 of the first lens L1 to the half-image height of the optical system 100, so that the two distribution schemes of the aperture stop STO can both obtain a good structural layout, and the difficulty of the structural design of the optical system 100 is reduced.

The optical system 100 satisfies the conditional expression: f is more than or equal to 17.9 mm; SD11/SD52 is 1.55; here, SD11 is half of the maximum effective diameter of the object-side surface S1 of the first lens L1, and SD52 is half of the maximum effective diameter of the image-side surface S10 of the fifth lens L5. The telephoto characteristic of the general optical system 100 is matched with the large aperture design, so that the diameter of the entrance pupil of the optical system 100 is equal to or larger than the size of the image plane, and two compact structures of each lens with the effective aperture rapidly reduced and each lens with the effective aperture slowly reduced are realized by the two distribution schemes of the aperture stop STO, and when the conditional expressions are satisfied, the two distribution schemes of the aperture stop STO can both obtain good structural layout, and the difficulty of the structural design of the optical system 100 is reduced. Meanwhile, the effective aperture of each lens of the optical system 100 can be reasonably changed, the bearing structure of each lens is convenient to design, and the manufacturability of the optical system 100 is improved.

In addition, the parameters of the optical system 100 are given in table 1. Among them, the image plane S13 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 S13 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, i.e., 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 in the same lens. 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 L6, but the distance from the image side surface S10 of the fifth lens L5 to the image surface S13 is kept constant at this time.

In the first embodiment, the effective focal length f of the optical system 100 is 18.20mm, the f-number FNO is 2.46, the maximum field angle FOV is 21.47 °, and the total optical length TTL is 17.04 mm. In the first embodiment and other embodiments, the effective focal lengths of the optical system 100 are all greater than or equal to 17.9mm, which indicates that the optical system 100 has a telephoto characteristic and the telephoto capability of the optical system 100 is improved. It can be seen from fig. 2 that the image height IMGH corresponding to the maximum field angle of the optical system 100 is 7.04mm, and in the first embodiment and the other embodiments, the image height corresponding to the maximum field angle of the optical system 100 is greater than or equal to 6.7mm, and the optical system 100 has a characteristic of a large image plane, which is advantageous for achieving high-pixel and high-quality effects.

In the first embodiment and other embodiments, the optical system satisfies the relationship: f is more than or equal to 17.9mm and less than or equal to 22.0mm, and the optical system 100 has a long-focus characteristic and good telephoto capability.

The reference wavelengths of the focal length, refractive index and abbe number of each lens are 587nm (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. Wherein, the surface numbers represent the image side or the object side S1-S10 from 1-10, respectively. And K-a20 from top to bottom respectively represent types of aspheric coefficients, where K represents a conic coefficient, a4 represents a quartic aspheric coefficient, a6 represents a sextic aspheric coefficient, A8 represents an octal aspheric coefficient, and so on. In addition, the aspherical surface coefficient formula is as follows:

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

TABLE 2

In addition, fig. 2 includes a Longitudinal Spherical Aberration diagram (Longitudinal Spherical Aberration) of the optical system 100, which shows the deviation of the converging focal points of the light rays of different wavelengths after passing through the lens. The ordinate of the longitudinal spherical aberration diagram represents 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 587nm and the T curve represents meridional field curvature at 587 nm. As can be seen from the figure, the curvature of field of the optical system 100 is small, the curvature of field and astigmatism of each field are well corrected, and the center and the edge of the field have clear images. Fig. 2 also includes a DISTORTION map (distorsion) of the optical system 100, and it can be seen that the image DISTORTION caused by the main beam is small and the imaging quality of the system is excellent.

Second embodiment

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

the 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 convex at a paraxial region 110 and convex at a peripheral region;

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 deduced:

(43/IMGH)*f	109.32	f12/f45	0.87
				OAL/BF	0.51	(CT12+CT34+CT45)/CT5	1.88
\|f5\|/FNO	12.37mm	\|f2\|/\|R22\|	7.93
				R32/\|R41\|	0.55	SD11/SD52	1.54
f/IMGH	2.54	SD11/IMGH	0.51

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, and the optical system 100 includes, in order from an object side to an image side, an aperture stop STO, a first lens element L1 with positive 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, and a fifth lens element L5 with negative refractive power. Fig. 6 is a graph of longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the third embodiment, from left to right.

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

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

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

the object-side surface S5 of the third lens element L3 is convex at a paraxial region 110 and convex at a peripheral region;

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

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

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

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

TABLE 6

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

(43/IMGH)*f	116.08	f12/f45	1.01
				OAL/BF	0.67	(CT12+CT34+CT45)/CT5	2.31
\|f5\|/FNO	17.61mm	\|f2\|/\|R22\|	0.81
				R32/\|R41\|	0.49	SD11/SD52	1.48
f/IMGH	2.70	SD11/IMGH	0.65

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

Fourth embodiment

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

the 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 S9 of the fifth lens element L5 is convex at a position near the optical axis 110 and is concave at 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

(43/IMGH)*f	116.36	f12/f45	1.33
				OAL/BF	0.56	(CT12+CT34+CT45)/CT5	3.06
\|f5\|/FNO	23.32mm	\|f2\|/\|R22\|	6.16
				R32/\|R41\|	0.70	SD11/SD52	1.47
f/IMGH	2.70	SD11/IMGH	0.65

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, an aperture stop STO, a third lens element L3 with negative refractive power, a fourth lens element L4 with positive refractive power, and a fifth lens element L5 with positive refractive power. Fig. 10 is a graph showing the longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the fifth embodiment from left to right.

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

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

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

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

the object-side surface S7 of the fourth lens element L4 is concave at a paraxial region 110 and concave at a peripheral region;

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

the object-side surface S9 of the fifth lens element L5 is convex at the paraxial region 110 and is convex at the peripheral region;

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

(43/IMGH)*f	115.09	f12/f45	0.92
				OAL/BF	0.48	(CT12+CT34+CT45)/CT5	1.08
\|f5\|/FNO	7.10mm	\|f2\|/\|R22\|	1.42
				R32/\|R41\|	0.16	SD11/SD52	1.16
f/IMGH	2.68	SD11/IMGH	0.66

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 structural diagram of the optical system 100 in the sixth 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, an aperture stop STO, a third lens element L3 with negative refractive power, a fourth lens element L4 with positive refractive power, and a fifth lens element L5 with positive refractive power. Fig. 12 is a graph showing the longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the sixth embodiment in order from left to right.

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

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

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

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

the image-side surface S10 of the fifth lens element L5 is convex at the paraxial region 110 and is convex at the periphery.

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

(43/IMGH)*f	115.04	f12/f45	0.82
				OAL/BF	0.47	(CT12+CT34+CT45)/CT5	0.96
\|f5\|/FNO	7.46mm	\|f2\|/\|R22\|	1.60
				R32/\|R41\|	0.12	SD11/SD52	1.13
f/IMGH	2.67	SD11/IMGH	0.66

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.

Seventh embodiment

Referring to fig. 13 and 14, fig. 13 is a schematic structural diagram of the optical system 100 in the seventh 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, an aperture stop STO, a third lens element L3 with negative refractive power, a fourth lens element L4 with positive refractive power, and a fifth lens element L5 with positive refractive power. Fig. 14 is a graph showing the longitudinal spherical aberration, astigmatism and distortion of the optical system 100 in the seventh embodiment from left to right.

the object-side surface S9 of the fifth lens element L5 is convex at a paraxial region 110 and convex at a peripheral region;

In addition, the parameters of the optical system 100 are given in table 13, and the definitions of the parameters can be obtained from the first embodiment, which is not described herein.

Watch 13

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 14, and the definitions of the parameters can be obtained from the first embodiment, which is not repeated herein.

TABLE 14

(43/IMGH)*f	113.75	f12/f45	1.09
				OAL/BF	0.45	(CT12+CT34+CT45)/CT5	0.67
\|f5\|/FNO	7.57mm	\|f2\|/\|R22\|	1.49
				R32/\|R41\|	0.52	SD11/SD52	1.12
f/IMGH	2.64	SD11/IMGH	0.64

in addition, as can be seen from the aberration diagram in fig. 14, 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. 15, in some embodiments, the optical system 100 may be assembled with the photosensitive element 210 to form an image capturing module 200. At this time, the light-sensing surface of the light-sensing element 210 can be regarded as the image surface S13 of the optical system 100. The image capturing module 200 may further include an infrared filter L6, and the infrared filter L6 is disposed between the image side surface S10 and the image surface S13 of the fifth lens element L5. Specifically, the photosensitive element 210 may be a Charge Coupled Device (CCD) or a Complementary Metal-Oxide Semiconductor (CMOS) Device. The optical system 100 is adopted in the image capturing module 200, so that the long-focus characteristic can be realized, and the telephoto performance is good.

Referring to fig. 15 and 16, 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 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, so that the long-focus characteristic can be realized, and the electronic device has good telephoto performance. It can be understood that the optical system 100 has good telephoto performance, so that the image capturing module 200 can be applied to a rear camera of the electronic device 300, so that the rear camera can capture a long-distance subject.

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, wherein five lenses having refractive power are provided, the optical system sequentially including, from an object side to an image side along an optical axis:

and the optical system satisfies the following conditional expression:

105.0≤(43/IMGH)*f≤120.0；

0.4≤OAL/BF≤0.7；

the IMGH is an image height corresponding to a maximum field angle of the optical system, f is an effective focal length of the optical system, OAL is a distance on an optical axis from an object side surface of the first lens to an image side surface of the fifth lens, and BF is a shortest distance in an optical axis direction from the image side surface of the fifth lens to an imaging surface of the optical system.

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

2.5≤f/IMGH≤2.7。

3. the optical system according to claim 1, further comprising an aperture stop disposed on an object side of the third lens.

4. An optical system according to claim 3, characterized in that the following conditional expression is satisfied:

2.0≤FNO≤2.55；

7.0mm≤|f5|/FNO≤24.0mm；

where f5 is an effective focal length of the fifth lens, and FNO is an f-number of the optical system.

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

R32/|R41|≤0.7；

wherein R32 is a curvature radius of an image-side surface of the third lens element at an optical axis, and R41 is a curvature radius of an object-side surface of the fourth lens element at the optical axis.

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

f12＞0；

f45＞0；

0.8≤f12/f45≤1.4；

wherein f12 is a combined focal length of the first lens and the second lens, and f45 is a combined focal length of the fourth lens and the fifth lens.

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

f12＞0；

f45＞0；

CT45≤0.6；

0.6≤(CT12+CT34+CT45)/CT5≤3.1；

wherein f12 is a combined focal length of the first lens element and the second lens element, f45 is a combined focal length of the fourth lens element and the fifth lens element, CT12 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, CT34 is a distance on an optical axis from an image-side surface of the third lens element to an object-side surface of the fourth lens element, CT45 is a distance on an optical axis from an image-side surface of the fourth lens element to an object-side surface of the fifth lens element, and CT5 is a thickness of the fifth lens element on the optical axis.

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

f1≤10.5mm；

0.8≤|f2|/|R22|≤8.0；

wherein f1 is an effective focal length of the first lens, f2 is an effective focal length of the second lens, and R22 is a curvature radius of an image side surface of the second lens at an optical axis.

9. The optical system according to claim 1, further comprising an aperture stop that is provided on an object-side surface of the first lens or between the second lens and the third lens, and satisfies the following conditional expression:

0.50≤SD11/IMGH≤0.7；

wherein SD11 is half of the maximum effective aperture of the object side surface of the first lens.

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

1.0≤SD11/SD52≤1.6；

wherein SD52 is half of the maximum effective aperture of the image-side surface of the fifth lens element.

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

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