CN111308668A

CN111308668A - Optical system, lens module and terminal equipment

Info

Publication number: CN111308668A
Application number: CN202010261413.0A
Authority: CN
Inventors: 张文燕; 李明; 杨健; 邹海荣
Original assignee: OFilm Tech Co Ltd
Current assignee: Nanchang OFilm Precision Optical Products Co Ltd; OFilm Group Co Ltd
Priority date: 2020-04-03
Filing date: 2020-04-03
Publication date: 2020-06-19

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, a fourth lens element with positive refractive power, a second lens element with positive refractive power, a third lens element with positive refractive power, and a fifth lens element with positive refractive power, wherein an object-side surface of the first lens element is convex at an optical axis, an object-side surface of the third lens element is concave at the optical axis, an image-side surface of the fourth lens element is convex at the optical axis, an object-side surface of the fifth lens element is concave at the optical axis, and an image-side surface of the fifth lens element is convex at the optical axis. The optical system satisfies the following conditional expression: 0.25< ftgtl3/ftltl3<0.8, ftgtl3 and ftltl3 are respectively the shortest and longest distances from the object-side surface of the third lens to the image-side surface of the third lens in a direction parallel to the optical axis. The refractive power of the first lens, the second lens, the third lens, the fourth lens and the fifth lens in the optical system and the surface type of the first lens, the third lens, the fourth lens and the fifth lens are reasonably configured, so that the optical system has the characteristic of long focal length, has good imaging quality and can realize high-definition long-range shooting.

Description

Optical system, lens module and terminal equipment

Technical Field

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

Background

With the wide application of mobile phones, tablet computers, unmanned planes, computers and other electronic products in life, various technological improvements are emerging. Among them, the improvement and innovation of the shooting effect of the camera lens in the novel electronic product become the key points of people's attention.

At present, along with the increase of the requirement of long-range shooting, the camera lens needs to have a long focal length, but the problem of image field curvature is easy to occur, and the integral imaging quality is difficult to ensure, so that the long-range shooting effect is poor.

Therefore, how to realize long-range shooting and high-definition shooting and avoid the problem of field curvature so as to clearly image a scene with a long object distance on an imaging surface is the research and development direction in the industry.

Disclosure of Invention

The embodiment of the application provides an optical system, a lens module and terminal equipment, and the optical system solves the problem of poor imaging quality in long-range shooting and can realize high-definition long-range shooting.

In a first aspect, an optical system includes, in order from an object side to an image side, a first lens element with positive refractive power, an object-side surface of the first lens element being convex at an optical axis; a second lens element with refractive power; the third lens element with refractive power has a concave object-side surface at an optical axis; the fourth lens element with positive refractive power has a convex image-side surface at an optical axis; the fifth lens element with refractive power has a concave object-side surface and a convex image-side surface; the optical system satisfies the following conditional expression: 0.25< ftgtl3/ftltl3< 0.8; ftgtl3 is the shortest distance from the object-side surface of the third lens to the image-side surface of the third lens in a direction parallel to the optical axis, and ftltl3 is the longest distance from the object-side surface of the third lens to the image-side surface of the third lens in a direction parallel to the optical axis.

The refractive power of the first lens to the fifth lens and the surface type of the first lens, the third lens, the fourth lens and the fifth lens in the optical system are reasonably configured, so that the optical system has the characteristic of long focal length and has good imaging quality, high-definition long-range shooting can be realized, meanwhile, 0.25< ftgtl3/ftltl3<0.8 can effectively balance the optical path difference of the optical system, the function of correcting field curvature is realized, distortion around an image is avoided, the imaging effect is closer to a shot object, and a shot picture has high painting texture, high resolution and high definition.

In one embodiment, the optical system satisfies the conditional expression: 7mm < FNO x L1SD/tanFOV <15 mm; FNO is an f-number of the optical system, L1SD is an aperture of the first lens, and tanFOV is a tangent value of a maximum angle of view of the optical system. The f-number of the optical system and the aperture of the first lens determine the light entering amount of the whole optical system, the field angle size of the optical system determines the imaging field range of the optical system, the FNO L1SD/tanFOV is reasonably limited, the optical system can have enough light passing amount and proper field range, if FNO L1SD/tanFOV is larger than or equal to 15mm, the light entering the optical system is too large, the optical performance is reduced, and if FNO L1SD/tanFOV is smaller than 7mm, the brightness of an imaging surface is reduced, and the imaging quality is reduced.

In one embodiment, the optical system satisfies the conditional expression: 0.5< L1SD/Imgh < 0.8; l1SD is the aperture of the first lens element, and Imgh is half the length of the diagonal line of the effective pixel area on the imaging plane of the optical system. The aperture of the first lens of the optical system determines the light transmission quantity of the whole optical system, the size of the light sensing surface determines the image definition and the pixel size of the whole optical system, and the proper arrangement of the range of L1SD/Imgh can ensure enough light transmission quantity and the definition of a shot image. If L1SD/Imgh >0.8, the exposure is too large, the brightness is too high, and the picture quality is affected, if L1SD/Imgh <0.5, the light transmission is insufficient, the relative brightness of the light is insufficient, and the picture definition is reduced.

In one embodiment, the optical system satisfies the conditional expression: 1< EFL/f1< 3; EFL is the effective focal length of the optical system, and f1 is the focal length of the first lens. The reasonable arrangement of the focal length of the first lens and the effective focal length of the optical system is beneficial to optimizing the imaging performance of the optical system and reducing the sensitivity of the system. If EFL/f1 is less than or equal to 1, the sensitivity of the system is increased, the processing process is difficult, the aberration generated by the first lens is difficult to correct, and the shooting requirement is difficult to meet, if EFL/f1 is more than 3, the focal length of the first lens is not properly configured with the effective focal length of the optical system, and the aberration generated by the first lens cannot be corrected.

In one embodiment, the optical system satisfies the conditional expression: 0.05< air 2/TTL < 0.35; airL2 is a distance on an optical axis from an image-side surface of the second lens element to an object-side surface of the third lens element, and TTL is a distance on the optical axis from an object-side surface of the first lens element to an image plane of the optical system. Through reasonable limitation on the range of air L2/TTL, the assembly sensitivity of the optical system is favorably reduced, the assembly yield is improved, if air L2/TTL is greater than 0.35, the system is too long and cannot meet the requirement of miniaturization design, and if air L2/TTL is less than 0.05, the sensitivity of the optical system is increased, so that the production yield is reduced.

In one embodiment, the optical system satisfies the conditional expression: -1< (| R9| - | R10|)/(| R9| + | R10|) < 0.1; r9 is a radius of curvature of an object-side surface of the fifth lens at an optical axis, and R10 is a radius of curvature of an image-side surface of the fifth lens at the optical axis. By limiting the range of (| R9| - | R10|)/(| R9| + | R10|), the spherical aberration of the optical system can be corrected, the optical path difference of the optical system is balanced, the field curvature is corrected, the system sensitivity is reduced, and the assembly stability is improved. If (| R9| - | R10|)/(| R9| + | R10|) >0.1, the field curvature of the optical system is too large, and if (| R9| - | R10|)/(| R9| + | R10|) -1, the system sensitivity is increased, and the production yield is reduced.

In one embodiment, the optical system further comprises a diaphragm, and the optical system satisfies the conditional expression: 0.3< DL/TTL < 0.6; DL is an aperture of the diaphragm of the optical system, and TTL is a distance on an optical axis from an object-side surface of the first lens element to an imaging surface of the optical system. The appropriate range of DL/TTL is limited, miniaturization of an optical system is facilitated, enough light transmission amount is provided for shooting, high-image-quality and high-definition shooting effect is achieved, if DL/TTL is larger than 0.6, the light transmission aperture is too large, marginal light rays enter the optical system, imaging quality is reduced, if DL/TTL is smaller than 0.3, the light transmission aperture of a diaphragm is too small, the light transmission amount required by the optical system cannot be met, and the requirement of long-range high-definition shooting cannot be met.

In one embodiment, the optical system satisfies the conditional expression: FNO/TTL<0.5mm^-1(ii) a The FNO is the f-number of the optical system, and the TTL is the distance from the object side surface of the first lens to the imaging surface of the optical system on the optical axis. The miniaturization of the optical system can be realized by limiting the proper range of the FNO/TTL, enough light flux can be provided for long-range shooting, the shooting requirements of high image quality and high definition are met, and if the FNO/TTL is used, the FNO/TTL is used>0.5mm^-1The amount of light passing through the optical system is insufficient, and the sharpness of the captured image is reduced.

In one embodiment, the optical system satisfies the conditional expression: 0.8< TTL/EFL < 1; TTL is a distance on an optical axis from an object-side surface of the first lens element to an image plane of the optical system, and EFL is an effective focal length of the optical system. The focal length of the optical system and the total length of the optical system can be reasonably controlled by limiting the TTL/EFL range, so that the miniaturization of the optical system can be realized, and meanwhile, the light can be guaranteed to better converge on an imaging surface. If TTL/EFL is less than or equal to 0.8, the total length of the optical system is too short, which may cause the sensitivity of the system to increase, and at the same time, it is not favorable for the light to converge on the imaging surface, and if TTL/EFL is greater than or equal to 1, the total length of the optical system is too long, which may cause the angle of the chief ray incident on the imaging surface to be too large, and the marginal ray may not be incident on the photosensitive surface, resulting in incomplete imaging information.

In one embodiment, the optical system satisfies the conditional expression: 1.5< EFL/Imgh < 2; EFL is the effective focal length of the optical system, and Imgh is half of the length of the diagonal line of the effective pixel area of the optical system on an imaging surface. The focal length and the image height of the optical system can be reasonably controlled by limiting the range of the EFL/Imgh, so that high-definition long-range shooting can be realized, and light can be guaranteed to better converge on an imaging surface. If EFL/Imgh is less than or equal to 1.5, the focal length can be reduced under the condition of ensuring that the image height is not changed, the requirement of long-range shooting cannot be met, and if EFL/Imgh is more than or equal to 2, the light rays cannot be ensured to be converged on an imaging surface.

In a second aspect, the present application provides a lens module, which includes a photosensitive element and the optical system of any one of the foregoing embodiments, wherein the photosensitive element is located on an image side of the optical system.

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

Drawings

In order to more clearly illustrate the technical solutions in the embodiments or the background art of the present application, the drawings required to be used in the embodiments or the background art of the present application 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 longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the first embodiment;

FIG. 4 is a schematic diagram of an optical system provided in a second embodiment of the present application;

FIG. 5 is a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the second embodiment;

FIG. 6 is a schematic diagram of an optical system provided in a third embodiment of the present application;

fig. 7 is a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the third embodiment;

FIG. 8 is a schematic diagram of an optical system according to a fourth embodiment of the present application;

fig. 9 is a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the fourth embodiment;

fig. 10 is a schematic structural diagram of an optical system provided in a fifth embodiment of the present application;

fig. 11 is a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the fifth embodiment;

fig. 12 is a schematic structural diagram of an optical system provided in a sixth embodiment of the present application;

fig. 13 is a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the sixth embodiment;

fig. 14 is a schematic structural diagram of an optical system provided in a seventh embodiment of the present application;

fig. 15 is a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the seventh embodiment.

Detailed Description

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

Referring to fig. 1, the optical system 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 tablet computer, an unmanned aerial vehicle, a computer, or the like. The light sensing element of the lens module 20 is located at the image side of the optical system, and the lens module 20 is assembled inside the terminal device 30.

The application provides a lens module, including photosensitive element and the optical system that this application embodiment provided, photosensitive element is located optical system's image side for incidenting the light on the electron photosensitive element and passing first lens to fifth lens converts the signal of telecommunication of image into. The electron sensor may be a Complementary Metal Oxide Semiconductor (CMOS) or a Charge-coupled Device (CCD). The optical system is arranged in the lens module, so that the lens module has the characteristic of long focal length and good imaging quality, and high-definition long-range shooting can be realized.

The application further provides a terminal device, and the terminal device comprises the lens module provided by the embodiment of the application. The terminal equipment can be a mobile phone, a tablet personal computer, an unmanned aerial vehicle, a computer and the like. The lens module is installed in the terminal equipment, so that the terminal equipment has the characteristic of long focal length, has good imaging quality and can realize high-definition long-range shooting.

An optical system provided by the present application includes five lenses, which are, in order from an object side to an image side, a first lens, a second lens, a third lens, a fourth lens and a fifth lens.

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

The optical system satisfies the following conditional expression: 0.25< ftgtl3/ftltl3< 0.8; ftgtl3 is the shortest distance from the object-side surface of the third lens to the image-side surface of the third lens in a direction parallel to the optical axis, and ftltl3 is the longest distance from the object-side surface of the third lens to the image-side surface of the third lens in a direction parallel to the optical axis.

The refractive power of the first lens, the second lens, the third lens, the fourth lens and the fifth lens in the optical system are reasonably configured, so that the optical system has the characteristic of long focal length, and has good imaging quality, high-definition long-range shooting can be realized, meanwhile, 0.25< ftgtl3/ftltl3<0.8 can effectively balance the optical path difference of the optical system, realize the function of correcting curvature of field, avoid distortion around the image, enable the imaging effect to be closer to the shot object, and enable the shot picture to have high painting quality, high resolution and high definition.

Through the definition of the above parameters, the optical system has good imaging quality, for example, it is preferable that: the value of ftgtl3/ftltl3 may be 0.52, 0.58, 0.47, etc., the value of FNO L1SD/tanFOV may be 12.84mm, 12.91mm, 12.86mm, etc., the value of L1SD/Imgh may be 0.75, 0.73, 0.70, etc., the value of EFL/f1 may be 2.29, 2.27, 2.43, etc., the value of airL2/TTL may be 0.24, 0.32, 0.25, etc.

The optical system is provided with an aspheric lens, which is beneficial to correcting system aberration and improving system imaging quality. The aspheric curve equation includes, but is not limited to, the following equation:

wherein Z is a distance from a corresponding point on the aspherical surface to a plane tangent to the surface vertex, r is a distance from a corresponding point on the aspherical surface to the optical axis, c is a 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.

The present application is described in detail below with seven specific examples.

Example one

As shown in fig. 2, a straight line 11 indicates an optical axis, a side of the first lens L1 away from the second lens L2 is an object side 12, and a side of the fifth lens L5 away from the fourth lens L4 is an image side 13. 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 12 to the image side 13.

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

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

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

The fourth lens element L4 with positive refractive power has a concave object-side surface S7 along the optical axis and at the circumference, and a convex image-side surface S8 along the optical axis and at the circumference.

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

The stop STO may be located between the object side of the optical system and the fifth lens, and the stop STO in the present embodiment is provided on the side of the first lens L1 away from the second lens L2, for controlling the amount of incoming light.

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.

The image forming surface S13 is a surface on which an image is formed by the light of the subject passing through the optical system.

Table 1a shows a characteristic table of the optical system of the present embodiment, in which the radius of curvature in the present embodiment is the radius of curvature of each lens at the optical axis.

TABLE 1a

The EFL is an effective focal length of the optical system, the FNO is an f-number of the optical system, the FOV is a field angle of the optical system in a diagonal direction, and the 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.

Table 1b shows the high-order term coefficients A4, A6, A8, a10, a12, a14, a16, a18, and a20 that can be used for each of the aspherical mirrors S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10 in the first embodiment.

TABLE 1b

Number of noodles	K	A4	A6	A8	A10
						S1	-1.832E+00	3.487E-02	-9.900E-03	3.075E-02	-5.322E-02
S2	1.700E+00	-1.524E-01	4.125E-01	-5.156E-01	3.029E-01
						S3	-8.333E+00	-1.752E-01	4.285E-01	-3.103E-01	-3.492E-01
S4	-3.176E+00	-2.762E-02	1.335E-01	-3.617E-02	-1.321E-01
						S5	1.700E+00	6.510E-03	-1.392E-01	7.190E-01	-2.324E+00
S6	-6.890E+01	6.766E-02	-1.346E-01	6.933E-01	-1.927E+00
						S7	-3.247E+00	-4.579E-02	6.882E-02	-5.229E-02	1.757E-02
S8	-1.864E+00	2.071E-02	3.011E-02	-1.352E-01	1.542E-01
						S9	-2.026E+00	2.419E-01	-2.527E-01	1.145E-02	1.493E-01
S10	-1.698E+00	1.738E-01	-1.950E-01	4.966E-02	6.214E-02
						Number of noodles	A12	A14	A16	A18	A20
S1	5.638E-02	-3.661E-02	1.412E-02	-2.960E-03	2.500E-04
						S2	4.750E-03	-1.264E-01	8.044E-02	-2.201E-02	2.330E-03
S3	9.765E-01	-9.441E-01	4.765E-01	-1.247E-01	1.334E-02
						S4	-3.469E-02	5.911E-01	-8.190E-01	4.669E-01	-9.936E-02
S5	4.460E+00	-5.272E+00	3.687E+00	-1.374E+00	2.041E-01
						S6	3.211E+00	-3.315E+00	2.056E+00	-6.973E-01	9.884E-02
S7	-7.660E-03	1.484E-02	-1.152E-02	3.590E-03	-4.000E-04
						S8	-1.096E-01	5.712E-02	-1.974E-02	3.790E-03	-3.000E-04
S9	-1.264E-01	5.343E-02	-1.308E-02	1.780E-03	-1.000E-04
						S10	-6.310E-02	2.644E-02	-5.960E-03	7.100E-04	-4.000E-05

Fig. 3 shows a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the first embodiment. The longitudinal spherical aberration curve represents the deviation of the convergence focus of the light rays with different wavelengths after passing through each lens of the optical system; the astigmatism curves represent meridional image surface curvature and sagittal image surface curvature; the distortion curve represents the distortion magnitude values corresponding to different angles of view. As can be seen from fig. 3, the optical system according to the first embodiment can achieve good imaging quality.

Example two

As shown in fig. 4, a straight line 11 indicates an optical axis, a side of the first lens L1 away from the second lens L2 is an object side 12, and a side of the fifth lens L5 away from the fourth lens L4 is an image side 13. 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 12 to the image side 13.

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

Table 2a shows a characteristic table of the optical system of the present embodiment, in which the radius of curvature in the present embodiment is the radius of curvature of each lens at the optical axis.

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 of the aspherical mirrors S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10 in the second embodiment.

TABLE 2b

Number of noodles	K	A4	A6	A8	A10
						S1	-1.757E+00	3.289E-02	-1.390E-03	5.200E-04	9.950E-03
S2	4.958E+01	-8.830E-02	1.962E-01	-2.367E-01	1.942E-01
						S3	-2.094E+01	-1.338E-01	3.086E-01	-3.060E-01	1.515E-01
S4	-2.631E+00	-6.285E-02	2.463E-01	-2.784E-01	3.201E-01
						S5	-2.424E+01	-2.500E-01	1.509E+00	-4.157E+00	7.618E+00
S6	-2.464E+01	-6.927E-02	1.092E+00	-2.640E+00	4.017E+00
						S7	-1.556E+01	9.229E-02	-3.215E-01	6.382E-01	-9.447E-01
S8	-4.220E+00	4.821E-01	-1.424E+00	2.144E+00	-2.091E+00
						S9	-1.889E+00	6.154E-01	-1.822E+00	2.723E+00	-2.458E+00
S10	-6.100E-01	3.557E-02	-9.998E-02	6.779E-02	3.331E-02
						Number of noodles	A12	A14	A16	A18	A20
S1	-1.949E-02	1.862E-02	-9.970E-03	2.850E-03	-3.400E-04
						S2	-1.163E-01	5.004E-02	-1.443E-02	2.450E-03	-1.900E-04
S3	-3.769E-02	2.209E-02	-2.281E-02	1.016E-02	-1.570E-03
						S4	-4.175E-01	3.815E-01	-1.299E-01	-3.522E-02	2.604E-02
S5	-9.462E+00	7.743E+00	-4.006E+00	1.197E+00	-1.590E-01
						S6	-3.935E+00	2.392E+00	-8.588E-01	1.687E-01	-1.504E-02
S7	9.440E-01	-5.830E-01	2.094E-01	-3.964E-02	3.020E-03
						S8	1.358E+00	-5.723E-01	1.486E-01	-2.141E-02	1.300E-03
S9	1.428E+00	-5.373E-01	1.268E-01	-1.709E-02	1.000E-03
						S10	-7.047E-02	4.176E-02	-1.246E-02	1.910E-03	-1.200E-04

Fig. 5 shows a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the second embodiment. The longitudinal spherical aberration curve represents the deviation of the convergence focus of the light rays with different wavelengths after passing through each lens of the optical system; the astigmatism curves represent meridional image surface curvature and sagittal image surface curvature; the distortion curve represents the distortion magnitude values corresponding to different angles of view. As can be seen from fig. 5, the optical system according to the second embodiment can achieve good imaging quality.

EXAMPLE III

As shown in fig. 6, a straight line 11 indicates an optical axis, a side of the first lens L1 away from the second lens L2 is an object side 12, and a side of the fifth lens L5 away from the fourth lens L4 is an image side 13. 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 12 to the image side 13.

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

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

Table 3a shows a characteristic table of the optical system of the present embodiment, in which the radius of curvature in the present embodiment is the radius of curvature of each lens at the optical axis.

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 of the aspherical mirrors S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10 in the third embodiment.

TABLE 3b

Fig. 7 shows a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the third embodiment. The longitudinal spherical aberration curve represents the deviation of the convergence focus of the light rays with different wavelengths after passing through each lens of the optical system; the astigmatism curves represent meridional image surface curvature and sagittal image surface curvature; the distortion curve represents the distortion magnitude values corresponding to different angles of view. As can be seen from fig. 7, the optical system according to the third embodiment can achieve good image quality.

Example four

As shown in fig. 8, a straight line 11 indicates an optical axis, a side of the first lens L1 away from the second lens L2 is an object side 12, and a side of the fifth lens L5 away from the fourth lens L4 is an image side 13. 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 12 to the image side 13.

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

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

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

Table 4a shows a characteristic table of the optical system of the present embodiment, in which the radius of curvature in the present embodiment is the radius of curvature of each lens at the optical axis.

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 of the aspherical mirrors S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10 in the fourth embodiment.

TABLE 4b

Fig. 9 shows a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the fourth embodiment. The longitudinal spherical aberration curve represents the deviation of the convergence focus of the light rays with different wavelengths after passing through each lens of the optical system; the astigmatism curves represent meridional image surface curvature and sagittal image surface curvature; the distortion curve represents the distortion magnitude values corresponding to different angles of view. As can be seen from fig. 9, the optical system according to the fourth embodiment can achieve good image quality.

EXAMPLE five

As shown in fig. 10, a straight line 11 indicates an optical axis, a side of the first lens L1 away from the second lens L2 is an object side 12, and a side of the fifth lens L5 away from the fourth lens L4 is an image side 13. 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 12 to the image side 13.

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

Table 5a shows a characteristic table of the optical system of the present embodiment, in which the radius of curvature in the present embodiment is the radius of curvature of each lens at the optical axis.

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 of the aspherical mirrors S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10 in the fifth embodiment.

TABLE 5b

Number of noodles	K	A4	A6	A8	A10
						S1	-1.808E+00	3.150E-02	-9.400E-04	5.050E-03	-8.420E-03
S2	-7.787E+01	-5.395E-02	1.062E-01	-1.453E-01	1.612E-01
						S3	-8.608E+01	-9.688E-02	2.035E-01	-2.729E-01	3.253E-01
S4	-5.455E+00	-5.019E-02	1.654E-01	-2.699E-01	6.022E-01
						S5	-2.048E+01	2.534E-02	-2.270E-03	-1.132E-01	3.384E-01
S6	-5.875E+01	7.911E-02	-2.146E-02	-3.933E-02	1.125E-01
						S7	1.751E+01	1.194E-02	-1.072E-02	-4.892E-02	8.226E-02
S8	-2.407E+00	7.588E-02	-4.397E-02	-8.105E-02	1.314E-01
						S9	-6.536E-01	2.007E-01	-2.252E-01	9.016E-02	-1.925E-02
S10	8.785E+00	1.215E-01	-1.456E-01	4.735E-02	1.922E-02
						Number of noodles	A12	A14	A16	A18	A20
S1	9.310E-03	-6.470E-03	2.720E-03	-6.400E-04	6.000E-05
						S2	-1.412E-01	9.046E-02	-3.878E-02	9.810E-03	-1.100E-03
S3	-3.276E-01	2.589E-01	-1.423E-01	4.687E-02	-6.870E-03
						S4	-1.190E+00	1.732E+00	-1.597E+00	8.293E-01	-1.822E-01
S5	-5.631E-01	5.829E-01	-3.562E-01	1.151E-01	-1.509E-02
						S6	-1.440E-01	1.028E-01	-3.639E-02	1.110E-03	1.820E-03
S7	-7.207E-02	3.966E-02	-1.405E-02	2.910E-03	-2.600E-04
						S8	-9.180E-02	3.856E-02	-1.064E-02	1.820E-03	-1.400E-04
S9	2.997E-02	-2.848E-02	1.131E-02	-2.040E-03	1.400E-04
						S10	-2.174E-02	8.210E-03	-1.670E-03	1.900E-04	-1.000E-05

Fig. 11 shows a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the fifth embodiment. The longitudinal spherical aberration curve represents the deviation of the convergence focus of the light rays with different wavelengths after passing through each lens of the optical system; the astigmatism curves represent meridional image surface curvature and sagittal image surface curvature; the distortion curve represents the distortion magnitude values corresponding to different angles of view. As can be seen from fig. 11, the optical system according to the fifth embodiment can achieve good image quality.

EXAMPLE six

As shown in fig. 12, a straight line 11 indicates an optical axis, a side of the first lens L1 away from the second lens L2 is an object side 12, and a side of the fifth lens L5 away from the fourth lens L4 is an image side 13. 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 12 to the image side 13.

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

Table 6a shows a characteristic table of the optical system of the present embodiment, in which the radius of curvature in the present embodiment is the radius of curvature of each lens at the optical axis.

TABLE 6a

Table 6b shows the high-order term coefficients A4, A6, A8, a10, a12, a14, a16, a18, and a20 that can be used for each of the aspherical mirrors S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10 in the sixth embodiment.

TABLE 6b

Number of noodles	K	A4	A6	A8	A10
						S1	-1.836E+00	3.403E-02	-4.620E-03	1.429E-02	-2.461E-02
S2	-9.900E+01	-1.033E-01	2.171E-01	-1.575E-01	-8.539E-02
						S3	-1.472E+01	-1.602E-01	3.275E-01	-7.152E-02	-6.963E-01
S4	-3.497E+00	-5.053E-02	1.691E-01	7.280E-03	-3.005E-01
						S5	-2.347E+00	-2.593E-02	3.578E-02	6.290E-03	-2.847E-01
S6	-9.900E+01	2.564E-02	4.207E-02	1.071E-02	-1.457E-01
						S7	-2.986E-01	-2.067E-02	4.781E-02	-1.185E-01	2.030E-01
S8	-1.913E+00	3.910E-02	6.690E-03	-2.199E-01	3.529E-01
						S9	-2.099E+00	2.205E-01	-1.752E-01	-1.833E-01	4.162E-01
S10	-1.624E+00	1.470E-01	-1.433E-01	2.892E-02	3.789E-02
						Number of noodles	A12	A14	A16	A18	A20
S1	2.814E-02	-2.067E-02	9.260E-03	-2.300E-03	2.400E-04
						S2	2.858E-01	-2.752E-01	1.394E-01	-3.746E-02	4.230E-03
S3	1.386E+00	-1.339E+00	7.339E-01	-2.187E-01	2.763E-02
						S4	3.859E-02	9.784E-01	-1.562E+00	1.005E+00	-2.427E-01
S5	8.831E-01	-1.465E+00	1.311E+00	-5.899E-01	1.039E-01
						S6	3.336E-01	-4.590E-01	3.544E-01	-1.389E-01	2.144E-02
S7	-2.174E-01	1.472E-01	-6.125E-02	1.416E-02	-1.380E-03
						S8	-2.799E-01	1.314E-01	-3.727E-02	5.940E-03	-4.100E-04
S9	-3.269E-01	1.400E-01	-3.467E-02	4.670E-03	-2.700E-04
						S10	-3.305E-02	1.227E-02	-2.480E-03	2.700E-04	-1.000E-05

Fig. 13 shows a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the sixth embodiment. The longitudinal spherical aberration curve represents the deviation of the convergence focus of the light rays with different wavelengths after passing through each lens of the optical system; the astigmatism curves represent meridional image surface curvature and sagittal image surface curvature; the distortion curve represents the distortion magnitude values corresponding to different angles of view. As can be seen from fig. 13, the optical system according to the sixth embodiment can achieve good image quality.

EXAMPLE seven

As shown in fig. 14, a straight line 11 indicates an optical axis, a side of the first lens L1 away from the second lens L2 is an object side 12, and a side of the fifth lens L5 away from the fourth lens L4 is an image side 13. 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 12 to the image side 13.

Table 7a shows a characteristic table of the optical system of the present embodiment, in which the radius of curvature in the present embodiment is the radius of curvature of each lens at the optical axis.

TABLE 7a

Table 7b shows the high-order term coefficients A4, A6, A8, a10, a12, a14, a16, a18, and a20 that can be used for each of the aspherical mirrors S1, S2, S3, S4, S5, S6, S7, S8, S9, and S10 in the seventh embodiment.

TABLE 7b

Number of noodles	K	A4	A6	A8	A10
						S1	-1.819E+00	3.418E-02	-2.440E-03	6.200E-03	-6.720E-03
S2	-9.900E+01	-8.565E-02	1.830E-01	-1.790E-01	6.950E-02
						S3	-2.139E+01	-1.487E-01	3.027E-01	-1.649E-01	-3.144E-01
S4	-3.599E+00	-5.408E-02	1.629E-01	4.510E-02	-5.885E-01
						S5	-3.817E+00	-5.298E-02	1.400E-01	-3.375E-01	8.252E-01
S6	-5.683E+01	-2.245E-02	1.149E-01	-1.256E-01	1.604E-01
						S7	7.826E+00	-5.200E-03	-3.994E-02	2.144E-01	-5.216E-01
S8	-2.370E+00	3.207E-02	-5.103E-02	1.535E-02	4.201E-02
						S9	-2.424E+00	2.058E-01	-2.445E-01	1.466E-02	2.313E-01
S10	-2.433E+00	1.869E-01	-1.983E-01	4.555E-02	6.310E-02
						Number of noodles	A12	A14	A16	A18	A20
S1	4.100E-03	-9.200E-04	-3.700E-04	2.600E-04	-5.000E-05
						S2	4.174E-02	-7.078E-02	3.959E-02	-1.063E-02	1.160E-03
S3	8.044E-01	-8.574E-01	5.071E-01	-1.619E-01	2.182E-02
						S4	1.117E+00	-9.788E-01	3.236E-01	7.505E-02	-5.805E-02
S5	-1.602E+00	1.983E+00	-1.440E+00	5.590E-01	-8.966E-02
						S6	-3.163E-01	4.124E-01	-2.827E-01	9.570E-02	-1.273E-02
S7	7.116E-01	-5.981E-01	3.014E-01	-8.205E-02	9.210E-03
						S8	-6.592E-02	4.560E-02	-1.782E-02	3.890E-03	-3.700E-04
S9	-2.449E-01	1.241E-01	-3.482E-02	5.210E-03	-3.300E-04
						S10	-6.113E-02	2.530E-02	-5.730E-03	7.000E-04	-4.000E-05

Fig. 15 shows a longitudinal spherical aberration curve, an astigmatism curve, and a distortion curve of the optical system of the seventh embodiment. The longitudinal spherical aberration curve represents the deviation of the convergence focus of the light rays with different wavelengths after passing through each lens of the optical system; the astigmatism curves represent meridional image surface curvature and sagittal image surface curvature; the distortion curve represents the distortion magnitude values corresponding to different angles of view. As can be seen from fig. 15, the optical system according to the seventh embodiment can achieve good image quality.

Table 8 shows values of ftgtl3/ftltl3, FNO × L1SD/tanFOV, L1SD/Imgh, EFL/f1, airL2/TTL, (| R9| - | R10|)/(| R9| + | R10|), DL/TTL, FNO/TTL, TTL/EFL, EFL/Imgh of the optical systems of the first to seventh embodiments.

TABLE 8

As can be seen from table 8, each example satisfies: 0.25<ftgtl3/ftltl3<0.8、7mm<FNO*L1SD/tanFOV<15mm、0.5<L1SD/Imgh<0.8、1<EFL/f1<3、0.05<airL2/TTL<0.35、-1<(|R9|-|R10|)/(|R9|+|R10|)<0.1、0.3<DL/TTL<0.6、FNO/TTL<0.5mm^-1、0.8<TTL/EFL<1、1.5<EFL/Imgh<2。

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, 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;

the third lens element with refractive power has a concave object-side surface at an optical axis;

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

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

the optical system satisfies the following conditional expression:

0.25<ftgtl3/ftltl3<0.8，

wherein ftgtl3 is the shortest distance from the object-side surface of the third lens to the image-side surface of the third lens in a direction parallel to the optical axis, and ftltl3 is the longest distance from the object-side surface of the third lens to the image-side surface of the third lens in a direction parallel to the optical axis.

2. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

7mm<FNO*L1SD/tanFOV<15mm，

wherein FNO is an f-number of the optical system, L1SD is an aperture of the first lens, and tanFOV is a tangent value of a maximum angle of view of the optical system.

3. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

0.5<L1SD/Imgh<0.8，

wherein L1SD is the aperture of the first lens element, and Imgh is half of the diagonal length of the effective pixel area on the imaging plane of the optical system.

4. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

1<EFL/f1<3，

where EFL is an effective focal length of the optical system, and f1 is a focal length of the first lens.

5. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

0.05<airL2/TTL<0.35，

wherein airL2 is a distance on an optical axis from an image-side surface of the second lens element to an object-side surface of the third lens element, and TTL is a distance on the optical axis from an object-side surface of the first lens element to an image plane of the optical system.

6. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

-1<(|R9|-|R10|)/(|R9|+|R10|)<0.1；

wherein R9 is a radius of curvature of an object-side surface of the fifth lens element at an optical axis, and R10 is a radius of curvature of an image-side surface of the fifth lens element at the optical axis.

7. The optical system according to claim 1, further comprising a diaphragm, the optical system satisfying the conditional expression:

0.3<DL/TTL<0.6，

wherein DL is an aperture of the diaphragm of the optical system, and TTL is a distance on an optical axis from an object-side surface of the first lens element to an imaging surface of the optical system.

8. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

FNO/TTL<0.5mm^-1，

the FNO is the f-number of the optical system, and the TTL is the distance from the object side surface of the first lens to the imaging surface of the optical system on the optical axis.

9. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

0.8<TTL/EFL<1，

wherein, TTL is a distance on an optical axis from an object-side surface of the first lens element to an image plane of the optical system, and EFL is an effective focal length of the optical system.

10. The optical system according to claim 1, wherein the optical system satisfies the conditional expression:

1.5<EFL/Imgh<2，

the EFL is the effective focal length of the optical system, and the Imgh is half of the length of a diagonal line of an effective pixel area of the optical system on an imaging surface.

11. A lens module comprising the optical system according to any one of claims 1 to 10 and a photosensitive element, wherein the photosensitive element is located on the image side of the optical system.

12. A terminal device characterized by comprising the lens module according to claim 11.