CN111239976A

CN111239976A - Optical system, lens module and terminal equipment

Info

Publication number: CN111239976A
Application number: CN202010177633.5A
Authority: CN
Inventors: 谭怡翔; 党绪文; 谢晗; 刘秀
Original assignee: OFilm Tech Co Ltd
Current assignee: OFilm Group Co Ltd
Priority date: 2020-03-13
Filing date: 2020-03-13
Publication date: 2020-06-05

Abstract

The embodiment of the application discloses an optical system, a lens module and terminal equipment. The optical system comprises a first lens element with positive refractive power, which is arranged from an object side to an image side along an optical axis, wherein an object side surface of the first lens element is convex at the optical axis; a second lens element with refractive power; a third lens element with refractive power; the fourth lens element with positive refractive power has a concave object-side surface and a convex image-side surface; the fifth lens element with negative refractive power has an image-side surface cemented with an object-side surface of the third lens element, and satisfies the following conditional expressions: 1.0mm^‑1＜(n2+n3)/f≤1.4mm^‑1(ii) a n2 is the refractive index of the second lens, n3 is the refractive index of the third lens, and f is the effective focal length of the optical system. Properly arranging the surface shapes and refractive powers of the first lens element to the fifth lens element and the refractive powers of (n2+ n3)/fThe ratio is obtained, and the second lens and the third lens are arranged to be cemented lenses, which is beneficial to improving the assembly yield of the optical system.

Description

Optical system, lens module and terminal equipment

Technical Field

The invention belongs to the technical field of optical imaging, and particularly relates to an optical system, a lens module and terminal equipment.

Background

With the development of science and technology and the popularization of smart phones and smart electronic devices, devices with image capturing functions are widely favored by people.

For reducing mobile intelligent device's weight and cost, getting for instance and having adopted plastic lens with the camera lens more, improved shaping efficiency like this, do benefit to the extensive volume production of camera lens, nevertheless because disconnect-type plastic lens light in weight, the size is little, and the number of pieces constantly increases, adopt the off-axis and the offset of negative pressure adsorption-type's assembly mode also to be difficult to control in the lens assembling process for the yield is difficult to promote.

How to design an image capturing optical lens device that is favorable for improving the assembly yield is a direction of research and development in the industry.

Disclosure of Invention

The embodiment of the application provides an optical system, a lens module and a terminal device, wherein the optical system is convenient to assemble, is beneficial to improving the assembly yield and has the characteristic of lower assembly sensitivity.

In a first aspect, an embodiment of the present application provides an optical system, including a plurality of lenses arranged in order from an object side to an image side along an optical axis, the plurality of lenses including a first lens element with positive refractive power, an object side surface of the first lens element being convex at the optical axis; a second lens element with refractive power; a third lens element with refractive power; the fourth lens element with positive refractive power has a concave object-side surface and a convex image-side surface; a fifth lens element with negative refractive power, wherein the image-side surface of the second lens element is cemented with the object-side surface of the third lens element, and the optical system satisfies the following conditional expression: 1.0mm^-1＜(n2+n3)/f≤1.4mm^-1(ii) a n2 is the refractive index of the second lens, n3 is the refractive index of the third lens, and f is the effective focal length of the optical system.

The surface types and the refractive powers of the first lens element to the fifth lens element and the ratio range of (n2+ n3)/f are limited in the optical system, and the second lens element and the third lens element are arranged to be cemented to form the cemented lens, so that the operation of coaxial alignment of the second lens element and the third lens element is avoided in the assembling process, the assembling yield of the optical system is improved, and the optical system has lower assembling sensitivity.

When the second lens element and the third lens element are combined into a cemented lens, the refractive powers of the second lens element and the third lens element are reasonably arranged by limiting the range of (n2+ n3)/f, thereby minimizing chromatic aberration and spherical aberration and improving image quality. Compared with a split lens, the achromatic capability is better, and the mechanical combination formed cemented lens has better assembly coaxiality than the split lens, so that the improvement of the assembly yield is facilitated, and meanwhile, the reduction of the comprehensive cost of the lens is facilitated.

In an embodiment, the object-side surface and/or the image-side surface of the fifth lens element are/is provided with inflection points, and the fifth lens element is provided with a plurality of inflection points, so that distortion and field curvature generated by the first lens element, the second lens element, the third lens element and the fourth lens element can be corrected, and the refractive power configuration near the image plane can be more uniform. The limitation of the refractive power of the first to fifth lenses and the limitation of the inflection point of the fifth lens are beneficial to improving the image quality.

In one embodiment, the optical system satisfies the conditional expression: -1.8 < f23/f < 11.5; f23 is the combined focal length of the second lens and the third lens, and f is the effective focal length of the optical system. The cemented lens is beneficial to reducing chromatic aberration, the gradual diffusion of light rays is facilitated through reasonable distribution of the refractive power of the second lens and the refractive power of the third lens, the overlarge light ray deflection angle caused by the fourth lens and the fifth lens is avoided, and the aberration generated by the cemented lens formed by combining the second lens and the third lens is compressed as much as possible by limiting-1.8 to f23/f to 11.5, so that the image quality is improved, and the assembly sensitivity is reduced.

In one embodiment, the optical system satisfies the conditional expression: -3.8 < (| f2| + | f3|)/R31 < 4.3; f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, and R31 is the radius of curvature of the object-side surface of the third lens at the optical axis. The third lens is matched with the cemented lens to adjust the refractive power, so that the comprehensive spherical aberration, chromatic aberration and distortion of the first lens, the second lens and the third lens are reduced to a reasonable range, and the design difficulty of the fourth lens and the fifth lens is reduced; by limiting the range (| f2| + | f3|)/R31, the curvature radius of the third lens is properly distributed, the surface type is prevented from being excessively complicated, and the lens forming and manufacturing are facilitated.

In one embodiment, the optical system satisfies the conditional expression: f/| f3| < 0.1 < 0.8; f3 is the effective focal length of the third lens, and f is the effective focal length of the optical system. The reasonable distribution of the refractive power of the third lens is beneficial to gradually diffusing light rays, the overlarge light ray deflection angle caused by the fourth lens and the fifth lens is avoided, and the aberration generated by the third lens can be compressed as much as possible by limiting the range of f/| f3|, so that the image quality is improved, and the assembly sensitivity is reduced.

In one embodiment, the optical system satisfies the conditional expression: 1.4 < EPD/SD31 < 1.9; EPD is the entrance pupil diameter of the optical system, SD31 is the optical effective radius length of the object side of the third lens. Through reasonable configuration of the EPD/SD31 range, the third lens and the first lens have similar optical apertures, so that the optical system has smaller volume, the lens arrangement and the size compression of a lens module are facilitated, meanwhile, the light angle deflection angle is reduced, and the sensitivity of the system is reduced.

In one embodiment, the optical system satisfies the conditional expression: 5 < (| f1| + | f2| + | f3|)/f < 14; f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, and f is the effective focal length of the optical system. By limiting the range (| f1| + | f2| + | f3|)/f and reasonably configuring the sizes and refractive powers of the first lens, the second lens and the third lens, larger spherical aberration generated by the first lens, the second lens and the third lens can be effectively avoided, the integral resolving power of the optical system is improved, and meanwhile, the size compression of the first lens, the second lens and the third lens is facilitated, and the small-size optical lens is facilitated to be formed.

In one embodiment, the optical system satisfies the conditional expression: r41/f 4 is more than or equal to 1.2 and less than 2.9; r41 is the radius of curvature of the object side of the fourth lens at the optical axis, f4 is the effective focal length of the fourth lens. The reasonable arrangement of the range of R41/f 4 and the reasonable arrangement of the focal power and the curvature radius of the fourth lens can ensure that the surface type complexity of the fourth lens is low, inhibit the increase of field curvature and distortion in the meridian direction to a certain extent, facilitate the reduction of the forming difficulty and improve the integral image quality.

In one embodiment, the optical system satisfies the conditional expression: i R41/R51I < 6; r41 is a radius of curvature of an object-side surface of the fourth lens at an optical axis, and R51 is a radius of curvature of an object-side surface of the fifth lens at the optical axis. The fourth lens element with positive refractive power can increase spherical aberration of system components, and the fifth lens element with multiple inflection points can reasonably distribute refractive power in the vertical direction, control overall aberration of the optical system, and contribute to reducing the size of the dispersed spot.

In one embodiment, the optical system satisfies the conditional expression: 1 < (| SAG51| + SAG52)/CT5 < 2.5; SAG51 is an on-axis distance between an intersection point of an object-side surface of the fifth lens and the optical axis and a maximum effective radius vertex of the object-side surface of the fifth lens, SAG52 is an on-axis distance between an intersection point of an image-side surface of the fifth lens and the optical axis and a maximum effective radius vertex of the image-side surface of the fifth lens, and CT5 is a thickness of the fifth lens on the optical axis. The reasonable configuration range of (| SAG51| + SAG52)/CT5 can effectively control the refractive power and thickness of the lens in the vertical direction, avoid the lens from being too thin or too thick, reduce the incident angle of light on an image plane and reduce the sensitivity of an optical system.

In one embodiment, the optical system satisfies the conditional expression: TTL is more than 3.4mm and less than 4.1 mm; TTL is a distance on the optical axis from the object-side surface of the first lens element to the imaging surface of the optical system. The miniaturization of the optical system is facilitated by the limitation of TTL.

In one embodiment, the optical system satisfies the conditional expression: FOV is more than or equal to 74 degrees and less than or equal to 92 degrees; the FOV is the field angle of the maximum field of view of the optical system.

In a second aspect, the present application provides a lens module, comprising a lens barrel and the optical system of any one of the foregoing embodiments, wherein the optical system is installed in the lens barrel.

In a third aspect, the present application provides a terminal device, including the lens module.

The surface shapes and the refractive powers of the first lens element to the fifth lens element and the range of (n2+ n3)/f are limited in the optical system, and the second lens element and the third lens element are arranged to be cemented to form the cemented lens, so that the assembly yield of the optical system is improved, the optical system has low sensitivity and the miniaturization is easy to realize.

Drawings

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

FIG. 1 is a schematic diagram of an optical system provided herein in a terminal device;

FIG. 2 is a schematic diagram of an optical system according to a first embodiment of the present application;

FIG. 3 is a spherical aberration curve of the optical system of the first embodiment;

fig. 4 is an astigmatism curve of the optical system of the first embodiment;

fig. 5 is a distortion curve of the optical system of the first embodiment;

FIG. 6 is a schematic diagram of an optical system according to a second embodiment of the present application;

FIG. 7 is a spherical aberration curve of the optical system of the second embodiment;

fig. 8 is an astigmatism curve of the optical system of the second embodiment;

FIG. 9 is a distortion curve of the optical system of the second embodiment;

FIG. 10 is a schematic diagram of an optical system provided in a third embodiment of the present application;

FIG. 11 is a spherical aberration curve of the optical system of the third embodiment;

fig. 12 is an astigmatism curve of the optical system of the third embodiment;

fig. 13 is a distortion curve of the optical system of the third embodiment;

FIG. 14 is a schematic diagram of an optical system according to a fourth embodiment of the present application;

FIG. 15 is a spherical aberration curve of the optical system of the fourth embodiment;

fig. 16 is an astigmatism curve of the optical system of the fourth embodiment;

fig. 17 is a distortion curve of the optical system of the fourth embodiment;

fig. 18 is a schematic structural diagram of an optical system provided in a fifth embodiment of the present application;

fig. 19 is a spherical aberration curve of the optical system of the fifth embodiment;

fig. 20 is an astigmatism curve of the optical system of the fifth embodiment;

fig. 21 is a distortion curve of the optical system of the fifth embodiment.

Detailed Description

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

Referring to fig. 1, the optical system 10 according to the present application is applied to a lens module 20 in a terminal device 30. The terminal device 30 may be a mobile phone, a monitor, a vehicle-mounted device, or the like. The optical system 10 is mounted in a lens barrel of a lens module 20, and the lens module 20 is assembled inside a terminal device 30.

In one embodiment, an optical system includes five lenses, which are respectively a first lens, a second lens, a third lens, a fourth lens and a fifth lens sequentially distributed from an object side to an image side along an optical axis. The second lens and the third lens form a cemented lens, and the cemented lens is beneficial to reducing chromatic aberration.

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

the first lens element with positive refractive power has a convex object-side surface at an optical axis; a second lens element with refractive power; a third lens element with refractive power; the fourth lens element with positive refractive power has a concave object-side surface and a convex image-side surface; the fifth lens element with negative refractive power.

Wherein, the image side surface of the second lens is glued with the object side surface of the third lens, and the optical system satisfies the following conditional expression: 1.0mm^-1＜(n2+n3)/f≤1.4mm^-1(ii) a n2 is the refractive index of the second lens, n3 is the refractive index of the third lens, and f is the effective focal length of the optical system.

The optical system is provided with a second lens and a third lens which are arranged in a cemented mode, the surface types and the refractive powers of the first lens to the fifth lens and the ratio range of (n2+ n3)/f are limited, and the second lens and the third lens are cemented to form the cemented lens, so that the assembly yield of the optical system is improved, and the optical system has low assembly sensitivity.

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

Example one

As shown in fig. 2, the middle straight line represents the optical axis, and the left side of the optical system is the object side and the right side is the image side. In the optical system provided in this embodiment, the stop STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, and the infrared filter element IRCF are arranged in order from the object side to the image side along the optical axis, wherein the second lens L2 and the third lens L3 are cemented lenses, and the cemented lenses are favorable for reducing chromatic aberration.

The first lens element L1 with positive refractive power has an object-side surface S1 being convex along the optical axis and at the circumference, an image-side surface S2 being concave along the optical axis, and an image-side surface S2 being convex along the circumference, and is aspheric.

The second lens element L2 with positive refractive power has an object-side surface S3 being convex at an optical axis and a circumference, an image-side surface S4 being concave at the optical axis, and an image-side surface S4 being convex at the circumference, and is made of plastic material.

The third lens element L3 with negative refractive power is made of plastic, and has a convex object-side surface S5 at the optical axis, a concave object-side surface S5 at the circumference, and a concave image-side surface S6 at the optical axis and the circumference.

The fourth lens element L4 with positive refractive power is made of plastic, and has an object-side surface S7 being concave at the optical axis and at the circumference and an image-side surface S8 being convex at the optical axis and at the circumference.

The fifth lens element L5 with negative refractive power has a concave object-side surface S9 at the optical axis and at the circumference, a concave image-side surface S10 at the optical axis, and a convex image-side surface S10 at the circumference.

The infrared filter element IRCF is arranged behind the fifth lens L5 and comprises an object side surface S11 and an image side surface S12, the infrared filter element IRCF is used for filtering infrared rays, the rays incident to the image side surface are visible rays, the wavelength of the visible rays is 380nm-780nm, and the infrared filter element IRCF is made of glass.

Table 1a shows a table of characteristics of the optical system of the present embodiment, and the units of the Y radius (i.e., radius of curvature), thickness, and focal length are all millimeters (mm).

TABLE 1a

Wherein f is an effective focal length of the optical system, FNO is an f-number of the optical system, FOV is a field angle of the optical system in a diagonal direction, and TTL is a distance from an object-side surface of the first lens to an imaging surface of the optical system on an optical axis.

S4/S5 indicates that the image-side surface of the second lens and the object-side surface of the third lens, and the image-side surface S4 of the second lens and the object-side surface S5 of the third lens are cemented together, and thus are represented as one surface on data.

In the present embodiment, the object-side surface and the image-side surface of any one of the first lens L1 through the fifth lens L5 are aspheric, and the surface shape of each aspheric lens can be defined by, but is not limited to, the following aspheric formula:

where Z is the distance from the corresponding point on the aspherical surface to a plane tangent to the surface vertex, r is the distance from the corresponding point on the aspherical surface to the optical axis, c is the curvature of the aspherical surface vertex, k is a conic constant, and Ai is a coefficient corresponding to the i-th high order term in the aspherical surface type formula, such as a4, a6, or A8.

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

TABLE 1b

FIG. 3 shows a spherical aberration curve of the optical system of the first embodiment, which represents the deviation of the converging focal points of light rays of different wavelengths after passing through the lenses of the optical system;

fig. 4 shows astigmatism curves of the optical system of the first embodiment, which represent meridional field curvature and sagittal field curvature;

fig. 5 shows distortion curves of the optical system of the first embodiment, which represent distortion magnitude values corresponding to different angles of view;

as can be seen from fig. 3, 4, and 5, the optical system according to the first embodiment can achieve good image quality.

Example two

As shown in fig. 6, the middle straight line represents the optical axis, and the left side of the optical system is the object side and the right side is the image side. In the optical system provided in this embodiment, the stop STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, and the infrared filter element IRCF are arranged in order from the object side to the image side along the optical axis, wherein the second lens L2 and the third lens L3 are cemented lenses, and the cemented lenses are favorable for reducing chromatic aberration.

The second lens element L2 with positive refractive power has an object-side surface S3 being convex at an optical axis and a circumference, and an image-side surface S4 being convex at the optical axis and the circumference.

The third lens element L3 with negative refractive power has a concave object-side surface S5 and a concave image-side surface S6.

Table 2a shows a table of characteristics of the optical system of the present embodiment, and the units of the Y radius (i.e., radius of curvature), thickness, and focal length are all millimeters (mm).

TABLE 2a

Table 2b shows the high-order term coefficients a4, A6, a8, a10, a12, a14, a16, a18, and a20 that can be used for each aspherical mirror surface S1, S2, S3, S4/S5, S6, S7, S8, S9, S10 in the second embodiment, wherein each aspherical surface type can be defined by the formula given in the first embodiment.

TABLE 2b

FIG. 7 shows a spherical aberration curve of the optical system of the second embodiment, which represents the deviation of the converging focal points of light rays of different wavelengths after passing through the lenses of the optical system;

FIG. 8 shows astigmatism curves of the optical system of the second embodiment, which represent meridional field curvature and sagittal field curvature;

fig. 9 shows distortion curves of the optical system of the second embodiment, which represent distortion magnitude values corresponding to different angles of view;

as can be seen from fig. 7, 8, and 9, the optical system according to the second embodiment can achieve good image quality.

EXAMPLE III

As shown in fig. 10, the middle straight line represents the optical axis, and the left side of the optical system is the object side and the right side is the image side. In the optical system provided in this embodiment, the stop STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, and the infrared filter element IRCF are arranged in order from the object side to the image side along the optical axis, wherein the second lens L2 and the third lens L3 are cemented lenses, and the cemented lenses are favorable for reducing chromatic aberration.

The first lens element L1 with positive refractive power has an object-side surface S1 being convex at an optical axis and a circumference, and an image-side surface S2 being convex at the optical axis and the circumference.

The second lens element L2 with positive refractive power is made of plastic, and has a convex object-side surface S3 at the optical axis, a concave object-side surface S3 at the circumference, and a concave image-side surface S4 at the optical axis and the circumference.

The third lens element L3 with negative refractive power has an object-side surface S5 being convex at an optical axis and a circumference, and an image-side surface S6 being concave at the optical axis and the circumference.

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

Table 3a shows a table of characteristics of the optical system of the present embodiment, and the units of the Y radius (i.e., radius of curvature), thickness, and focal length are all millimeters (mm).

TABLE 3a

Table 3b shows the high-order term coefficients a4, A6, a8, a10, a12, a14, a16, a18, and a20 that can be used for each aspherical mirror surface S1, S2, S3, S4/S5, S6, S7, S8, S9, S10 in the third embodiment, wherein each aspherical surface type can be defined by the formula given in the first embodiment.

TABLE 3b

FIG. 11 shows a spherical aberration curve of the optical system of the third embodiment, which represents the deviation of the converging focal points of light rays of different wavelengths after passing through the lenses of the optical system;

fig. 12 shows astigmatism curves of the optical system of the third embodiment, which represent meridional field curvature and sagittal field curvature;

fig. 13 shows distortion curves of the optical system of the third embodiment, which represent distortion magnitude values corresponding to different angles of view;

as can be seen from fig. 11, 12, and 13, the optical system according to the third embodiment can achieve good image quality.

Example four

As shown in fig. 14, the middle straight line represents the optical axis, and the left side of the optical system is the object side and the right side is the image side. In the optical system provided in this embodiment, the stop STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, and the infrared filter element IRCF are arranged in order from the object side to the image side along the optical axis, wherein the second lens L2 and the third lens L3 are cemented lenses, and the cemented lenses are favorable for reducing chromatic aberration.

The second lens element L2 with negative refractive power has a concave object-side surface S3 at the optical axis and circumference and a convex image-side surface S4 at the optical axis and circumference, and is made of plastic material.

The third lens element L3 with negative refractive power has a concave object-side surface S5 at the optical axis and at the circumference, a concave image-side surface S6 at the optical axis, and a convex image-side surface S6 at the circumference.

The fifth lens element L5 with negative refractive power is made of plastic material, and has an object-side surface S9 being concave at the optical axis and circumference and an image-side surface S10 being convex at the optical axis and circumference.

Table 4a shows a table of characteristics of the optical system of the present embodiment, and the units of the Y radius (i.e., radius of curvature), thickness, and focal length are all millimeters (mm).

TABLE 4a

Table 4b shows the high-order term coefficients a4, A6, a8, a10, a12, a14, a16, a18, and a20 that can be used for each aspherical mirror surface S1, S2, S3, S4/S5, S6, S7, S8, S9, S10 in the fourth embodiment, wherein each aspherical surface type can be defined by the formula given in the first embodiment.

TABLE 4b

FIG. 15 shows a spherical aberration curve of the optical system of the fourth embodiment, which represents the deviation of the converging focal points of light rays of different wavelengths after passing through the lenses of the optical system;

fig. 16 shows astigmatism curves of the optical system of the fourth embodiment, which represent meridional field curvature and sagittal field curvature;

fig. 17 shows distortion curves of the optical system of the fourth embodiment, which represent distortion magnitude values corresponding to different angles of view;

as can be seen from fig. 15, 16, and 17, the optical system according to the fourth embodiment can achieve good image quality.

EXAMPLE five

As shown in fig. 18, the middle straight line represents the optical axis, and the left side of the optical system is the object side and the right side is the image side. In the optical system provided in this embodiment, the stop STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, and the infrared filter element IRCF are arranged in order from the object side to the image side along the optical axis, wherein the second lens L2 and the third lens L3 are cemented lenses, and the cemented lenses are favorable for reducing chromatic aberration.

The second lens element L2 with negative refractive power has a concave object-side surface S3 at the optical axis and at the circumference, a convex image-side surface S4 at the optical axis, and a concave image-side surface S4 at the circumference.

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

Table 5a shows a table of characteristics of the optical system of the present embodiment, and the units of the Y radius (i.e., radius of curvature), thickness, and focal length are all millimeters (mm).

TABLE 5a

Table 5b shows the high-order term coefficients a4, A6, a8, a10, a12, a14, a16, a18, and a20 that can be used for each aspherical mirror surface S1, S2, S3, S4/S5, S6, S7, S8, S9, S10 in the fifth embodiment, wherein each aspherical surface type can be defined by the formula given in the first embodiment.

TABLE 5b

FIG. 19 shows a spherical aberration curve of the optical system of the fifth embodiment, which represents the deviation of the converging focal points of light rays of different wavelengths after passing through the lenses of the optical system;

fig. 20 shows astigmatism curves of the optical system of the fifth embodiment, which represent meridional field curvature and sagittal field curvature;

fig. 21 shows distortion curves of the optical system of the fifth embodiment, which represent distortion magnitude values corresponding to different angles of view;

as can be seen from fig. 19, 20, and 21, the optical system according to the fifth embodiment can achieve good image quality.

Table 6 shows the (n2+ n3)/f values of the optical systems of the first to fifth embodiments, and as can be seen from table 6, the respective embodiments satisfy the conditions: 1.0mm^-1＜(n2+n3)/f＜1.4mm^-1。

TABLE 6

	(n2+n3)/f
		First embodiment	1.01
Second embodiment	1.13
		Third embodiment	1.22
Fourth embodiment	1.35
		Fifth embodiment	1.36

Table 7 shows (| SAG51| + SAG52)/CT5 values of the optical systems of the first to fifth embodiments, and as can be seen from table 7, the respective embodiments satisfy the conditions: 1 < (| SAG51| + SAG52)/CT5 < 2.5.

TABLE 7

	(\|SAG51\|+SAG52)/CT5
		First embodiment	1.30
Second embodiment	2.44
		Third embodiment	0.98
Fourth embodiment	1.30
		Fifth embodiment	1.66

Table 8 shows the (| f2| + | f3|)/R31 values of the optical systems of the first to fifth embodiments, and as can be seen from table 8, each embodiment satisfies the condition: -3.8 < (| f2| + | f3|)/R31 < 4.3.

TABLE 8

Table 9 shows f23/f values of the optical systems of the first to fifth embodiments, and as can be seen from table 9, the respective embodiments satisfy the conditions: -1.8 < f23/f < 11.5.

TABLE 9

	f23/f
		First embodiment	1.80
Second embodiment	2.45
		Third embodiment	-3.44
Fourth embodiment	-1.74
		Fifth embodiment	11.54

Table 10 shows EPD/SD31 values of the optical systems of the first to fifth embodiments, and as can be seen from table 10, the respective embodiments satisfy the conditions: 1.4 < EPD/SD31 < 1.9.

Watch 10

	EPD/SD31
		First embodiment	1.73
Second embodiment	1.81
		Third embodiment	1.52
Fourth embodiment	1.43
		Fifth embodiment	1.42

Table 11 shows the values of f/| f3| of the optical systems of the first to fifth embodiments, and as can be seen from table 11, the respective embodiments satisfy the conditions: 0.1 < f/| f3| < 0.8.

TABLE 11

	f/\|f3\|
		First embodiment	0.76
Second embodiment	0.36
		Third embodiment	0.74
Fourth embodiment	0.17
		Fifth embodiment	0.26

Table 12 shows the (| f1| + | f2| + | f3|)/f values of the optical systems of the first to fifth embodiments, and as can be seen from table 12, each embodiment satisfies the condition: 5 < (| f1| + | f2| + | f3|)/f < 14.

TABLE 12

	(\|f1\|+\|f2\|+\|f3\|)/f
		First embodiment	5.67
Second embodiment	7.62
		Third embodiment	7.20
Fourth embodiment	10.95
		Fifth embodiment	13.06

Table 13 shows | R41/R51| values of the optical systems of the first to fifth embodiments, and as can be seen from table 13, each embodiment satisfies the conditions: i R41/R51I < 6.

Watch 13

Table 14 shows the values of | R41|/f4 of the optical systems of the first to fifth embodiments, and as can be seen from table 14, each embodiment satisfies the condition: r41/f 4 is more than or equal to 1.2 and less than 2.9.

TABLE 14

	\|R41\|/f4
		First embodiment	1.67
Second embodiment	1.77
		Third embodiment	1.74
Fourth embodiment	2.02
		Fifth embodiment	1.23

The foregoing is a preferred embodiment of the present application, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present application, and these modifications and decorations are also regarded as the protection scope of the present application.

Claims

1. An optical system comprising a plurality of lenses arranged in order from an object side to an image side in an optical axis direction, the plurality of lenses comprising:

the first lens element with positive refractive power has a convex object-side surface at an optical axis;

a second lens element with refractive power;

a third lens element with refractive power;

the fourth lens element with positive refractive power has a concave object-side surface and a convex image-side surface;

a fifth lens element with negative refractive power;

the image side surface of the second lens is glued with the object side surface of the third lens, and the optical system meets the following conditional expression:

1.0mm^-1＜(n2+n3)/f≤1.4mm^-1；

n2 is the refractive index of the second lens, n3 is the refractive index of the third lens, and f is the effective focal length of the optical system.

2. The optical system of claim 1, wherein the object side surface and/or the image side surface of the fifth lens is provided with an inflection point.

3. The optical system according to any one of claims 1 to 2, wherein the optical system satisfies the conditional expression:

-1.8＜f23/f＜11.5；

f23 is the combined focal length of the second lens and the third lens, and f is the effective focal length of the optical system.

4. The optical system according to any one of claims 1 to 2, wherein the optical system satisfies the conditional expression:

-3.8＜(|f2|+|f3|)/R31＜4.3；

f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, and R31 is the radius of curvature of the object-side surface of the third lens at the optical axis.

5. The optical system according to any one of claims 1 to 2, wherein the optical system satisfies the conditional expression:

0.1＜f/|f3|＜0.8；

f3 is the effective focal length of the third lens, and f is the effective focal length of the optical system.

6. The optical system according to any one of claims 1 to 2, wherein the optical system satisfies the conditional expression:

1.4＜EPD/SD31＜1.9；

EPD is the entrance pupil diameter of the optical system, SD31 is the optical effective radius length of the object side of the third lens.

7. The optical system according to any one of claims 1 to 2, wherein the optical system satisfies the conditional expression:

5＜(|f1|+|f2|+|f3|)/f＜14；

f1 is the effective focal length of the first lens, f2 is the effective focal length of the second lens, f3 is the effective focal length of the third lens, and f is the effective focal length of the optical system.

8. The optical system according to any one of claims 1 to 2, wherein the optical system satisfies the conditional expression:

1.2≤|R41|/f4＜2.9；

r41 is the radius of curvature of the object side of the fourth lens at the optical axis, f4 is the effective focal length of the fourth lens.

9. The optical system according to any one of claims 1 to 2, wherein the optical system satisfies the conditional expression:

|R41/R51|＜6；

r41 is a radius of curvature of an object-side surface of the fourth lens at an optical axis, and R51 is a radius of curvature of an object-side surface of the fifth lens at the optical axis.

10. The optical system according to any one of claims 1 to 2, wherein the optical system satisfies the conditional expression:

1＜(|SAG51|+SAG52)/CT5＜2.5；

SAG51 is an on-axis distance between an intersection point of an object-side surface of the fifth lens and the optical axis and a maximum effective radius vertex of the object-side surface of the fifth lens, SAG52 is an on-axis distance between an intersection point of an image-side surface of the fifth lens and the optical axis and a maximum effective radius vertex of the image-side surface of the fifth lens, and CT5 is a thickness of the fifth lens on the optical axis.

11. The optical system according to any one of claims 1 to 2, wherein the optical system satisfies the conditional expression:

3.4mm＜TTL＜4.1mm；

TTL is a distance on the optical axis from the object-side surface of the first lens element to the imaging surface of the optical system.

12. The optical system according to any one of claims 1 to 2, wherein the optical system satisfies the conditional expression:

74°≤FOV≤92°；

the FOV is the field angle of the maximum field of view of the optical system.

13. A lens module comprising a lens barrel and the optical system according to any one of claims 1 to 12, the optical system being mounted in the lens barrel.

14. A terminal device characterized by comprising the lens module according to claim 13.