Optical System, Lens Module and Terminal Device

Abstract

Embodiments of the present application disclose an optical system, a lens module, and a terminal device. The optical system includes a first lens and a fifth lens having positive refractive power, and the remaining lenses have refractive power. The object sides of the first lens and the seventh lens are convex at the optical axis, the image sides of the second lens, the third lens, and the fifth lens are convex at the optical axis, the image side of the seventh lens is concave at the optical axis, and an inflection point is provided on the object side and / or the image side of the seventh lens; the optical system satisfies the following conditional formula: tanω / f > 0.21 mm-1, Y2 / Y1 + Y3 / Y1 + Y4 / Y1 < 3.1, where tanω is the tangent value of half of the maximum field of view angle of the optical system, f is the effective focal length of the optical system, and Y1, Y2, Y3, and Y4 are the maximum optical effective radii of the object sides of the first lens, the second lens, the third lens, and the fourth lens, respectively. By reasonably configuring the refractive power and surface shape of the first lens to the seventh lens, and simultaneously setting tanω / f > 0.21 and Y2 / Y1 + Y3 / Y1 + Y4 / Y1 < 3.1, the optical system has the characteristics of wide-angle and miniaturization, and has good imaging quality.

Description

Technical Field

[0001] This application belongs to the technical field of optical imaging, and particularly relates to an optical system, a lens module, and a terminal device. Background Art

[0002] In recent years, with the rise of portable electronic devices such as smart phones and tablet computers, people have more and more requirements for the camera lenses mounted on them. Among them, wide-angle lenses can capture a wider scene at a limited distance, greatly meeting the user experience and needs.

[0003] Generally, five-element wide-angle lenses are more commonly used on portable electronic products, and there are also six-element lens structures. However, it is difficult to balance the requirements of miniaturization and high imaging quality. Therefore, it is necessary to design a miniaturized wide-angle lens with good imaging quality to meet the user experience. Summary of the Invention

[0004] Embodiments of this application provide an optical system, a lens module, and a terminal device. The optical system solves the problems of miniaturization and high imaging quality of wide-angle lenses to improve the user experience.

[0005] In a first aspect, an embodiment of the present application provides an optical system, which sequentially includes, from the object side to the image side, a first lens having a positive refractive power, wherein the object side surface of the first lens is convex at the optical axis; a second lens having a refractive power, wherein the image side surface of the second lens is convex at the optical axis; a third lens having a refractive power, wherein the image side surface of the third lens is convex at the optical axis; a fourth lens having a refractive power; a fifth lens having a positive refractive power, wherein the image side surface of the fifth lens is convex at the optical axis; a sixth lens having a refractive power; and a seventh lens having a refractive power, wherein the object side surface of the seventh lens is convex at the optical axis, the image side surface of the seventh lens is concave at the optical axis, and an anastigmatic point is provided on the object side surface and / or the image side surface of the seventh lens. Herein, the refractive power is the optical power, which characterizes the ability of the optical system to deflect light rays. The fact that the second lens, the third lens, the fourth lens, the sixth lens, and the seventh lens have refractive power means that the second lens, the third lens, the fourth lens, the sixth lens, and the seventh lens may have a positive refractive power or a negative refractive power. A positive refractive power indicates that the lens converges the light beam, and a negative refractive power indicates that the lens diverges the light beam. For example, in a preferred embodiment, the refractive powers of the seven lenses may be such that the first lens has a positive refractive power, the second lens has a positive refractive power, the third lens has a negative refractive power, the fourth lens has a negative refractive power, the fifth lens has a positive refractive power, the sixth lens has a negative refractive power, and the seventh lens has a negative refractive power. The refractive powers of the seven lenses may also be other preferred combinations. When the lens has no refractive power, that is, when the optical power is zero, it is plane refraction. At this time, the axially parallel light beam remains axially parallel after refraction, and no refraction phenomenon occurs. The optical system satisfies the following conditional formula: tanω / f > 0.21mm -1 , Y2 / Y1 + Y3 / Y1 + Y4 / Y1 < 3.1, where tanω is the tangent value of half of the maximum field of view angle of the optical system, f is the effective focal length of the optical system, Y1 is the maximum optical effective radius of the object side surface of the first lens, Y2 is the maximum optical effective radius of the object side surface of the second lens, Y3 is the maximum optical effective radius of the object side surface of the third lens, and Y4 is the maximum optical effective radius of the object side surface of the fourth lens.

[0006] By reasonably configuring the refractive powers of the first lens to the seventh lens and the surface types of the first lens, the second lens, the third lens, the fifth lens, and the seventh lens in the optical system, and simultaneously setting tanω / f > 0.21 and Y2 / Y1 + Y3 / Y1 + Y4 / Y1 < 3.1, the optical system has the characteristics of wide-angle and miniaturization. The setting of the anastigmatic point can suppress the excessive increase of off-axis field incident light rays, can effectively correct aberrations and control distortion, and is beneficial to improving the imaging quality.

[0007] By restricting the maximum optical effective radii of the first lens, the second lens, the third lens, and the fourth lens, the optical system can have a smaller front aperture, meeting the requirement of a small head shape, that is, meeting the need for miniaturization of the optical system. If Y2 / Y1 + Y3 / Y1 + Y4 / Y1 ≥ 3.1, the aperture of any one of the first lens, the second lens, the third lens, and the fourth lens is too large, which will cause the volume of the front end of the entire optical system to become larger, being unfavorable for the miniaturization of the optical system. By reasonably configuring the range of tanω / f, the optical system has a wide-angle characteristic. If tanω / f ≤ 0.21, with the same focal length maintained, the field of view angle becomes smaller and the imaging picture becomes smaller.

[0008] In one implementation, the optical system satisfies the conditional formula: 1 < f1 / f < 1.6, where f is the effective focal length of the optical system and f1 is the focal length of the first lens. By reasonably configuring the ratio range of f1 / f, the system field curvature can be corrected, ensuring good imaging quality, and by reasonably shortening the effective focal length of the optical system, it is beneficial to shorten the overall length of the system, making the optical system have the characteristics of miniaturization.

[0009] In one implementation, f12 / f34 > -0.54, where f12 is the combined focal length of the first lens and the second lens, and f34 is the combined focal length of the third lens and the fourth lens. The combined lens formed by the first lens and the second lens provides positive optical power (i.e., refractive power), and the combined lens formed by the third lens and the fourth lens provides negative optical power, which is beneficial for correcting the spherical aberration generated by the first lens and the second lens. When f12 / f34 > -0.54, the optical system can have good imaging quality. When f12 / f34 ≤ -0.54, the combined focal length of the first lens and the second lens becomes larger and the positive optical power becomes smaller, being unfavorable for the improvement of imaging quality.

[0010] In one implementation, the optical system satisfies the conditional formula: 1.66 < n4 < 1.69, where n4 is the refractive index of the fourth lens. The fourth lens has a relatively high refractive index, which can improve the modulation transfer function of the system, making the system have excellent performance, and can also correct chromatic aberration to ensure imaging quality.

[0011] In one implementation, the optical system satisfies the conditional formula: 0.5 < f / f5 < 1.4, where f is the effective focal length of the optical system and f5 is the focal length of the fifth lens. The first lens provides most of the positive optical power for imaging, and the fifth lens compensates with the first lens to jointly provide positive optical power, improving imaging quality.

[0012] In one embodiment, the optical system satisfies the conditional formula: 3.7 < f / CT5 < 5.1, where f is the effective focal length of the optical system, and CT5 is the thickness of the fifth lens on the optical axis. The fifth lens has a positive optical power. By reasonably configuring the thickness of the fifth lens on the optical axis, the total length of the optical system can be effectively shortened, which is beneficial to the miniaturization of the optical system.

[0013] In one embodiment, the optical system satisfies the conditional formula: TTL / EPD < 2.8, where TTL is the distance from the object side of the first lens to the imaging surface of the optical system on the optical axis, and EPD is the entrance pupil diameter of the optical system. An optical system with seven lenses generally has a relatively large entrance pupil diameter to increase the light passing amount. By reasonably configuring the ratio of TTL / EPD, the total length of the system can be effectively compressed, meeting the miniaturization characteristics.

[0014] In one embodiment, the optical system satisfies the conditional formula: FNO / ImgH ≤ 0.55mm -1 , where FNO is the f-number of the optical system, and ImgH is half of the diagonal length of the effective pixel area on the imaging surface of the optical system. By defining a reasonable range of FNO / ImgH, the optical system can have a large aperture, improving the imaging quality.

[0015] In a second aspect, the present application provides a lens module, including a photosensitive element and the optical system according to any one of the foregoing embodiments, and the photosensitive element is located on the image side of the optical system.

[0016] In a third aspect, the present application provides a terminal device, including the lens module described above.

[0017] By reasonably configuring the refractive powers of the first lens to the seventh lens in the optical system and the surface shapes of the first lens, the second lens, the third lens, the fifth lens, and the seventh lens, and simultaneously setting tanω / f > 0.21, Y2 / Y1 + Y3 / Y1 + Y4 / Y1 < 3.1, the optical system has the characteristics of wide-angle and miniaturization. The setting of the inflection point can suppress the excessive increase of off-axis field incident light, effectively correct aberrations and control distortion, which is beneficial to improving the imaging quality. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the background art, the following will describe the drawings required to be used in the embodiments of the present application or the background art.

[0019] Figure 1 It is a schematic diagram of the optical system provided by the present application applied in a terminal device;

[0020] Figure 2It is a schematic structural diagram of the optical system provided by the first embodiment of the present application;

[0021] Figure 3 They are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the first embodiment;

[0022] Figure 4 It is a schematic structural diagram of the optical system provided by the second embodiment of the present application;

[0023] Figure 5 They are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the second embodiment;

[0024] Figure 6 It is a schematic structural diagram of the optical system provided by the third embodiment of the present application;

[0025] Figure 7 They are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the third embodiment;

[0026] Figure 8 It is a schematic structural diagram of the optical system provided by the fourth embodiment of the present application;

[0027] Figure 9 They are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the fourth embodiment;

[0028] Figure 10 It is a schematic structural diagram of the optical system provided by the fifth embodiment of the present application;

[0029] Figure 11 They are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the fifth embodiment;

[0030] Figure 12 It is a schematic structural diagram of the optical system provided by the sixth embodiment of the present application;

[0031] Figure 13 They are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the sixth embodiment;

[0032] Figure 14 It is a schematic structural diagram of the optical system provided by the seventh embodiment of the present application;

[0033] Figure 15 They are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the seventh embodiment;

[0034] Figure 16 It is a schematic structural diagram of the optical system provided by the eighth embodiment of the present application;

[0035] Figure 17 They are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the eighth embodiment. Detailed implementation manners

[0036] The embodiments of the present application will be described below with reference to the accompanying drawings in the embodiments of the present application.

[0037] Refer to Figure 1 , the optical system involved in the present application is applied to the lens module 20 in the terminal device 30. The terminal device 30 can be a device such as a mobile phone, a tablet computer, a drone, a computer, etc. The photosensitive element of the lens module 20 is located on the image side of the optical system, and the lens module 20 is assembled inside the terminal device 30.

[0038] The present application provides a lens module, including a photosensitive element and the optical system provided by the embodiments of the present application. The photosensitive element is located on the image side of the optical system and is used to convert the light passing through the first lens to the seventh lens and incident on the electronic photosensitive element into an electrical signal of an image. The electronic photosensitive element can be a Complementary Metal Oxide Semiconductor (CMOS) or a Charge-coupled Device (CCD). By installing the optical system in the lens module, the lens module has the characteristics of wide-angle and miniaturization, and has good imaging quality.

[0039] The present application also provides a terminal device, and the terminal device includes the lens module provided by the embodiments of the present application. The terminal device can be a mobile phone, a tablet computer, a drone, a computer, etc. By installing the lens module in the terminal device, the terminal device has the characteristics of wide-angle and miniaturization, and has good imaging quality.

[0040] An optical system provided by the present application includes seven lenses, and the seven lenses are sequentially distributed from the object side to the image side as the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens.

[0041] Specifically, the surface shapes and refractive powers of the seven lenses are as follows:

[0042] The first lens has a positive refractive power, and the object side surface of the first lens is convex at the optical axis; the second lens has a refractive power, and the image side surface of the second lens is convex at the optical axis; the third lens has a refractive power, and the image side surface of the third lens is convex at the optical axis; the fourth lens has a refractive power; the fifth lens has a positive refractive power, and the image side surface of the fifth lens is convex at the optical axis; the sixth lens has a refractive power; the seventh lens has a refractive power, the object side surface of the seventh lens is convex at the optical axis, the image side surface of the seventh lens is concave at the optical axis, and an inflection point is provided on the object side surface and / or the image side surface of the seventh lens.

[0043] The optical system satisfies the following conditional expressions: tanω / f > 0.21, Y2 / Y1 + Y3 / Y1 + Y4 / Y1 < 3.1, where tanω is the tangent value of half of the maximum field of view angle of the optical system, f is the effective focal length of the optical system, Y1 is the maximum optical effective radius of the object side surface of the first lens, Y2 is the maximum optical effective radius of the object side surface of the second lens, Y3 is the maximum optical effective radius of the object side surface of the third lens, and Y4 is the maximum optical effective radius of the object side surface of the fourth lens.

[0044] Reasonably configure the refractive powers of the first lens to the seventh lens and the surface shapes of the first lens, the second lens, the third lens, the fifth lens, and the seventh lens in the optical system, and at the same time set tanω / f > 0.21mm -1 , Y2 / Y1 + Y3 / Y1 + Y4 / Y1 < 3.1, so that the optical system has the characteristics of wide angle and miniaturization. The setting of the inflection point can suppress the excessive increase of off-axis field incident light, effectively correct aberration and control distortion, which is beneficial to improving the imaging quality.

[0045] By restricting the maximum optical effective radii of the first lens, the second lens, the third lens, and the fourth lens, the optical system can have a smaller front aperture, meeting the requirement of a small head shape, that is, meeting the miniaturization requirement of the optical system. If Y2 / Y1 + Y3 / Y1 + Y4 / Y1 ≥ 3.1, the aperture of any one of the first lens, the second lens, the third lens, and the fourth lens is too large, which will cause the front-end volume of the entire optical system to become larger, being unfavorable for the miniaturization of the optical system. By reasonably configuring the range of tanω / f, the optical system has wide-angle characteristics. If tanω / f ≤ 0.21, with the same focal length maintained, the field of view angle becomes smaller and the imaging picture becomes smaller.

[0046] In an implementation manner, the optical system satisfies the conditional expression: 1 < f1 / f < 1.6, where f is the effective focal length of the optical system and f1 is the focal length of the first lens. Reasonably configuring the ratio range of f1 / f can correct the field curvature of the system, ensure good imaging quality, and reasonably shorten the effective focal length of the optical system, which is beneficial to shortening the total length of the system and making the optical system have the characteristics of miniaturization.

[0047] In one embodiment, f12 / f34 > -0.54, where f12 is the combined focal length of the first lens and the second lens, and f34 is the combined focal length of the third lens and the fourth lens. The combined lens formed by the first lens and the second lens provides a positive optical power (i.e., refractive power), and the combined lens formed by the third lens and the fourth lens provides a negative optical power, which is beneficial to correcting the spherical aberration generated by the first lens and the second lens. When f12 / f34 > -0.54, the optical system can have good imaging quality. When f12 / f34 ≤ -0.54, the combined focal length of the first lens and the second lens becomes larger, and the positive optical power becomes smaller, which is not conducive to improving the imaging quality.

[0048] In one embodiment, the optical system satisfies the conditional formula: 1.66 < n4 < 1.69, where n4 is the refractive index of the fourth lens. The fourth lens has a high refractive index, which can improve the modulation transfer function of the system, enable the system to have excellent performance, and can correct chromatic aberration to ensure imaging quality.

[0049] In one embodiment, the optical system satisfies the conditional formula: 0.5 < f / f5 < 1.4, where f is the effective focal length of the optical system, and f5 is the focal length of the fifth lens. The first lens provides most of the positive optical power for imaging, and the fifth lens compensates with the first lens to jointly provide positive optical power to improve imaging quality.

[0050] In one embodiment, the optical system satisfies the conditional formula: 3.7 < f / CT5 < 5.1, where f is the effective focal length of the optical system, and CT5 is the thickness of the fifth lens on the optical axis. The fifth lens has a positive optical power. Reasonably configuring the thickness of the fifth lens on the optical axis can effectively shorten the total length of the optical system, which is beneficial to the miniaturization of the optical system.

[0051] In one embodiment, the optical system satisfies the conditional formula: TTL / EPD < 2.8, where TTL is the distance from the object side of the first lens to the imaging plane of the optical system on the optical axis, and EPD is the entrance pupil diameter of the optical system. An optical system with seven lenses generally configures a relatively large entrance pupil diameter to increase the light passing amount. Reasonably configuring the ratio of TTL / EPD can effectively compress the total length of the system and meet the characteristics of miniaturization.

[0052] In one embodiment, the optical system satisfies the conditional formula: FNO / ImgH ≤ 0.55mm -1 , where FNO is the f-number of the optical system, and ImgH is half of the diagonal length of the effective pixel area on the imaging plane of the optical system. By limiting the reasonable range of FNO / ImgH, the optical system can have a large aperture and improve imaging quality.

[0053] The optical system is provided with an aspherical lens, which is beneficial to correcting system aberrations and improving the imaging quality of the system. The aspherical curve equation includes but is not limited to the following equations:

[0054]

[0055] Wherein, Z is the distance from the corresponding point on the aspherical surface to the 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 vertex, k is the conic constant, and Ai is the coefficient corresponding to the i-th high-order term in the aspherical surface formula.

[0056] The following describes the present application in detail through eight specific embodiments.

[0057] Embodiment 1

[0058] As Figure 2 shown, the straight line 11 represents the optical axis. The side of the first lens L1 away from the second lens L2 is the object side 12, and the side of the seventh lens L7 away from the sixth lens L6 is the image side 13. In the optical system provided in this embodiment, from the object side 12 to the image side 13 are, in sequence, the aperture stop STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the infrared filter element IRCF. Among them, an inflection point is provided on the object side surface and / or the image side surface of the seventh lens L7.

[0059] The first lens L1 has a positive refractive power and is made of plastic. Its object side surface S1 is convex at the optical axis and at the circumference. Its image side surface S2 is concave at the optical axis and convex at the circumference, and both are aspherical surfaces.

[0060] The second lens L2 has a positive refractive power and is made of plastic. Its object side surface S3 is concave at the optical axis and at the circumference. Its image side surface S4 is convex at the optical axis and at the circumference, and both are aspherical surfaces.

[0061] The third lens L3 has a negative refractive power and is made of plastic. Its object side surface S5 is concave at the optical axis and at the circumference. Its image side surface S6 is convex at the optical axis and at the circumference, and both are aspherical surfaces.

[0062] The fourth lens L4 has a negative refractive power and is made of plastic. Its object side surface S7 is concave at the optical axis and at the circumference. Its image side surface S8 is concave at the optical axis and convex at the circumference, and both are aspherical surfaces.

[0063] The fifth lens L5 has a positive refractive power and is made of plastic. Its object side surface S9 is concave at the optical axis and at the circumference. Its image side surface S10 is convex at the optical axis and at the circumference, and both are aspherical surfaces.

[0064] The sixth lens L6 has a negative refractive power and is made of plastic. Its object side S11 is concave at the optical axis and at the circumference. Its image side S12 is concave at the optical axis and convex at the circumference, and all are aspherical surfaces.

[0065] The seventh lens L7 has a negative refractive power and is made of plastic. Its object side S13 is convex at the optical axis and at the circumference. Its image side S14 is concave at the optical axis and convex at the circumference, and all are aspherical surfaces.

[0066] The aperture stop STO can be located between the object side of the optical system and the seventh lens. In this embodiment, the aperture stop STO is arranged on the side of the first lens L1 away from the second lens L2 to control the amount of incident light.

[0067] The infrared filter element IRCF is arranged behind the seventh lens L7 and includes an object side S15 and an image side S16. The infrared filter element IRCF is used to filter out infrared light so that the light incident on the imaging surface is visible light. The wavelength of the visible light is 380nm - 780nm, and the material of the infrared filter element IRCF is glass.

[0068] The imaging surface S17 is the surface where the image of the light of the object to be photographed is formed after passing through the optical system.

[0069] Table 1a shows the characteristic table of the optical system of this embodiment.

[0070] Table 1a

[0071]

[0072] Among them, f is the effective focal length of the optical system, FNO is the f-number of the optical system, FOV is the field angle in the diagonal direction of the optical system, and TTL is the distance from the object side of the first lens to the imaging surface of the optical system on the optical axis.

[0073] Table 1b gives the higher-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, S11, S12, S13, S14 in the first embodiment.

[0074] Table 1b

[0075]

[0076]

[0077] Figure 3The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the first embodiment are shown. Among them, the longitudinal spherical aberration curve represents the deviation of the convergence points of light rays of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the curvature of the meridional image plane and the sagittal image plane; the distortion curve represents the distortion magnitude values corresponding to different field angles. According to Figure 3 it can be known that the optical system given in the first embodiment can achieve good imaging quality.

[0078] Embodiment 2

[0079] As Figure 4 shown, the straight line 11 represents the optical axis. The side of the first lens L1 away from the second lens L2 is the object side 12, and the side of the seventh lens L7 away from the sixth lens L6 is the image side 13. In the optical system provided in this embodiment, from the object side 12 to the image side 13, there are successively a stop STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and an infrared filter element IRCF. Among them, an inflection point is provided on the object side surface and / or the image side surface of the seventh lens L7.

[0080] The first lens L1 has a positive refractive power and is made of plastic. Its object side surface S1 is convex at the optical axis and at the circumference. Its image side surface S2 is concave at the optical axis and convex at the circumference, and both are aspherical surfaces.

[0081] The second lens L2 has a positive refractive power and is made of plastic. Its object side surface S3 is concave at the optical axis and at the circumference. Its image side surface S4 is convex at the optical axis and at the circumference, and both are aspherical surfaces.

[0082] The third lens L3 has a negative refractive power and is made of plastic. Its object side surface S5 is concave at the optical axis and at the circumference. Its image side surface S6 is convex at the optical axis and at the circumference, and both are aspherical surfaces.

[0083] The fourth lens L4 has a negative refractive power and is made of plastic. Its object side surface S7 is concave at the optical axis and at the circumference. Its image side surface S8 is concave at the optical axis and convex at the circumference, and both are aspherical surfaces.

[0084] The fifth lens L5 has a positive refractive power and is made of plastic. Its object side surface S9 is concave at the optical axis and at the circumference. Its image side surface S10 is convex at the optical axis and at the circumference, and both are aspherical surfaces.

[0085] The sixth lens L6 has a negative refractive power and is made of plastic. Its object side surface S11 is concave at the optical axis and at the circumference. Its image side surface S12 is concave at the optical axis and convex at the circumference, and both are aspherical surfaces.

[0086] The seventh lens L7 has a negative refractive power and is made of plastic. Its object side S13 is convex at the optical axis and at the circumference. Its image side S14 is concave at the optical axis and convex at the circumference, and all are aspherical surfaces.

[0087] The aperture stop STO can be located between the object side of the optical system and the seventh lens. In this embodiment, the aperture stop STO is arranged on the side of the first lens L1 away from the second lens L2 to control the amount of incident light.

[0088] The infrared filter element IRCF is arranged behind the seventh lens L7 and includes an object side S15 and an image side S16. The infrared filter element IRCF is used to filter out infrared light so that the light incident on the imaging surface is visible light. The wavelength of the visible light is 380nm - 780nm, and the material of the infrared filter element IRCF is glass.

[0089] The imaging surface S17 is the surface where the image of the light of the object to be photographed is formed after passing through the optical system.

[0090] Table 2a shows the characteristic table of the optical system of this embodiment.

[0091] Table 2a

[0092]

[0093]

[0094] Among them, f is the effective focal length of the optical system, FNO is the f-number of the optical system, FOV is the field angle in the diagonal direction of the optical system, and TTL is the distance from the object side of the first lens to the imaging surface of the optical system on the optical axis.

[0095] Table 2b gives the higher-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for the aspherical mirror surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, and S14 in the second embodiment.

[0096] Table 2b

[0097]

[0098]

[0099] Figure 5 Shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the second embodiment. Among them, the longitudinal spherical aberration curve represents the deviation of the focusing points of light rays of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the curvature of the meridional image plane and the sagittal image plane; the distortion curve represents the distortion magnitude values corresponding to different field angles. According toFigure 5 It can be seen that the optical system given in the second embodiment can achieve good imaging quality.

[0100] Embodiment Three

[0101] As Figure 6 shown, the straight line 11 represents the optical axis. The side of the first lens L1 away from the second lens L2 is the object side 12, and the side of the seventh lens L7 away from the sixth lens L6 is the image side 13. In the optical system provided in this embodiment, from the object side 12 to the image side 13 are, in sequence, the aperture stop STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the infrared filter element IRCF. Among them, the object side surface and / or the image side surface of the seventh lens L7 is provided with an inflection point.

[0102] The first lens L1 has a positive refractive power and is made of plastic. Its object side surface S1 is convex at the optical axis and at the circumference. Its image side surface S2 is concave at the optical axis and convex at the circumference, and both are aspherical surfaces.

[0103] The second lens L2 has a negative refractive power and is made of plastic. Its object side surface S3 is concave at the optical axis and at the circumference. Its image side surface S4 is convex at the optical axis and at the circumference, and both are aspherical surfaces.

[0104] The third lens L3 has a positive refractive power and is made of plastic. Its object side surface S5 is concave at the optical axis and at the circumference. Its image side surface S6 is convex at the optical axis and at the circumference, and both are aspherical surfaces.

[0105] The fourth lens L4 has a negative refractive power and is made of plastic. Its object side surface S7 is concave at the optical axis and at the circumference. Its image side surface S8 is concave at the optical axis and convex at the circumference, and both are aspherical surfaces.

[0106] The fifth lens L5 has a positive refractive power and is made of plastic. Its object side surface S9 is concave at the optical axis and at the circumference. Its image side surface S10 is convex at the optical axis and at the circumference, and both are aspherical surfaces.

[0107] The sixth lens L6 has a negative refractive power and is made of plastic. Its object side surface S11 is concave at the optical axis and at the circumference. Its image side surface S12 is concave at the optical axis and convex at the circumference, and both are aspherical surfaces.

[0108] The seventh lens L7 has a negative refractive power and is made of plastic. Its object side surface S13 is convex at the optical axis and concave at the circumference. Its image side surface S14 is concave at the optical axis and convex at the circumference, and both are aspherical surfaces.

[0109] The aperture STO can be located between the object side of the optical system and the seventh lens. In this embodiment, the aperture STO is disposed on the side of the first lens L1 away from the second lens L2 for controlling the amount of incident light.

[0110] The infrared filter element IRCF is disposed behind the seventh lens L7, including an object side surface S15 and an image side surface S16. The infrared filter element IRCF is used to filter out infrared light so that the light incident on the imaging surface is visible light, and the wavelength of the visible light is 380nm - 780nm. The material of the infrared filter element IRCF is glass.

[0111] The imaging surface S17 is the surface where the image of the light of the object to be photographed is formed after passing through the optical system.

[0112] Table 3a shows the characteristic table of the optical system of this embodiment.

[0113] Table 3a

[0114]

[0115]

[0116] Among them, f is the effective focal length of the optical system, FNO is the f-number of the optical system, FOV is the field of view angle in the diagonal direction of the optical system, and 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.

[0117] Table 3b gives the higher-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, S11, S12, S13, S14 in the third embodiment.

[0118] Table 3b

[0119]

[0120]

[0121] Figure 7 Shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the third embodiment. Among them, the longitudinal spherical aberration curve represents the deviation of the convergence points of light rays of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the curvature of the meridional image plane and the sagittal image plane; the distortion curve represents the distortion magnitude values corresponding to different field of view angles. According to Figure 7 It can be seen that the optical system given in the third embodiment can achieve good imaging quality.

[0122] Embodiment Four

[0123] AsFigure 8 As shown, the straight line 11 represents the optical axis. The side of the first lens L1 away from the second lens L2 is the object side 12, and the side of the seventh lens L7 away from the sixth lens L6 is the image side 13. In the optical system provided in this embodiment, from the object side 12 to the image side 13, there are, in sequence, the aperture stop STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the infrared filter element IRCF. Among them, the object side surface and / or the image side surface of the seventh lens L7 is provided with an anastigmatic point.

[0124] The first lens L1 has a positive refractive power and is made of plastic. Its object side surface S1 is convex at the optical axis and at the circumference. Its image side surface S2 is concave at the optical axis and convex at the circumference, and both are aspherical surfaces.

[0125] The second lens L2 has a positive refractive power and is made of plastic. Its object side surface S3 is concave at the optical axis and at the circumference. Its image side surface S4 is convex at the optical axis and at the circumference, and both are aspherical surfaces.

[0126] The third lens L3 has a negative refractive power and is made of plastic. Its object side surface S5 is concave at the optical axis and at the circumference. Its image side surface S6 is convex at the optical axis and at the circumference, and both are aspherical surfaces.

[0127] The fourth lens L4 has a positive refractive power and is made of plastic. Its object side surface S7 is concave at the optical axis and at the circumference. Its image side surface S8 is convex at the optical axis and at the circumference, and both are aspherical surfaces.

[0128] The fifth lens L5 has a positive refractive power and is made of plastic. Its object side surface S9 is concave at the optical axis and at the circumference. Its image side surface S10 is convex at the optical axis and at the circumference, and both are aspherical surfaces.

[0129] The sixth lens L6 has a negative refractive power and is made of plastic. Its object side surface S11 is concave at the optical axis and at the circumference. Its image side surface S12 is concave at the optical axis and convex at the circumference, and both are aspherical surfaces.

[0130] The seventh lens L7 has a negative refractive power and is made of plastic. Its object side surface S13 is convex at the optical axis and concave at the circumference. Its image side surface S14 is concave at the optical axis and convex at the circumference, and both are aspherical surfaces.

[0131] The aperture stop STO can be located between the object side of the optical system and the seventh lens. In this embodiment, the aperture stop STO is arranged on the side of the first lens L1 away from the second lens L2 to control the amount of incident light.

[0132] The infrared filter element IRCF is disposed behind the seventh lens L7 and includes an object side surface S15 and an image side surface S16. The infrared filter element IRCF is used to filter out infrared light so that the light incident on the imaging surface is visible light, and the wavelength of the visible light is 380 nm - 780 nm. The material of the infrared filter element IRCF is glass.

[0133] The imaging surface S17 is the surface where the image of the light of the object to be photographed is formed after passing through the optical system.

[0134] Table 4a shows the characteristic table of the optical system of this embodiment.

[0135] Table 4a

[0136]

[0137]

[0138] Among them, f is the effective focal length of the optical system, FNO is the f-number of the optical system, FOV is the field of view angle in the diagonal direction of the optical system, and 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.

[0139] Table 4b gives 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, S11, S12, S13, S14 in the fourth embodiment.

[0140] Table 4b

[0141]

[0142]

[0143] Figure 9 Shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the fourth embodiment. Among them, the longitudinal spherical aberration curve represents the deviation of the convergence points of light rays of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the curvature of the meridional image plane and the sagittal image plane; the distortion curve represents the distortion magnitude values corresponding to different field of view angles. According to Figure 9 It can be seen that the optical system given in the fourth embodiment can achieve good imaging quality.

[0144] Embodiment Five

[0145] As Figure 10As shown in the figure, the straight line 11 represents the optical axis. The side of the first lens L1 away from the second lens L2 is the object side 12, and the side of the seventh lens L7 away from the sixth lens L6 is the image side 13. In the optical system provided in this embodiment, from the object side 12 to the image side 13, there are, in sequence, a stop STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and an infrared filter element IRCF. Among them, an anastigmatic point is provided on the object side surface and / or the image side surface of the seventh lens L7.

[0146] The first lens L1 has a positive refractive power and is made of plastic. Its object side surface S1 is convex at the optical axis and at the circumference, its image side surface S2 is concave at the optical axis, and its image side surface S2 is convex at the circumference, and all are aspherical surfaces.

[0147] The second lens L2 has a positive refractive power and is made of plastic. Its object side surface S3 is concave at the optical axis and at the circumference, its image side surface S4 is convex at the optical axis and at the circumference, and all are aspherical surfaces.

[0148] The third lens L3 has a negative refractive power and is made of plastic. Its object side surface S5 is concave at the optical axis and at the circumference, its image side surface S6 is convex at the optical axis and at the circumference, and all are aspherical surfaces.

[0149] The fourth lens L4 has a negative refractive power and is made of plastic. Its object side surface S7 is concave at the optical axis and at the circumference, its image side surface S8 is convex at the optical axis and at the circumference, and all are aspherical surfaces.

[0150] The fifth lens L5 has a positive refractive power and is made of plastic. Its object side surface S9 is concave at the optical axis and at the circumference, its image side surface S10 is convex at the optical axis and at the circumference, and all are aspherical surfaces.

[0151] The sixth lens L6 has a positive refractive power and is made of plastic. Its object side surface S11 is convex at the optical axis and concave at the circumference, its image side surface S12 is concave at the optical axis and convex at the circumference, and all are aspherical surfaces.

[0152] The seventh lens L7 has a negative refractive power and is made of plastic. Its object side surface S13 is convex at the optical axis and concave at the circumference, its image side surface S14 is concave at the optical axis and convex at the circumference, and all are aspherical surfaces.

[0153] The stop STO can be located between the object side of the optical system and the seventh lens. In this embodiment, the stop STO is arranged on the side of the first lens L1 away from the second lens L2 and is used to control the amount of incident light.

[0154] The infrared filter element IRCF is disposed behind the seventh lens L7, and includes an object side surface S15 and an image side surface S16. The infrared filter element IRCF is used to filter out infrared light so that the light incident on the imaging surface is visible light, and the wavelength of the visible light is 380nm - 780nm. The material of the infrared filter element IRCF is glass.

[0155] Imaging surface S17: The surface where the image formed by the light of the object to be photographed passes through the optical system.

[0156] Table 5a shows the characteristic table of the optical system of this embodiment.

[0157] Table 5a

[0158]

[0159]

[0160] Among them, f is the effective focal length of the optical system, FNO is the f-number of the optical system, FOV is the field of view angle in the diagonal direction of the optical system, and 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.

[0161] Table 5b gives the higher-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for the aspherical mirror surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14 in the fifth embodiment.

[0162] Table 5b

[0163]

[0164]

[0165] Figure 11 Shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the fifth embodiment. Among them, the longitudinal spherical aberration curve represents the deviation of the convergence points of light rays of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the curvature of the meridional image plane and the sagittal image plane; the distortion curve represents the distortion magnitude values corresponding to different field of view angles. According to Figure 11 It can be seen that the optical system given in the fifth embodiment can achieve good imaging quality.

[0166] Embodiment Six

[0167] As Figure 12As shown in the figure, the straight line 11 represents the optical axis. The side of the first lens L1 away from the second lens L2 is the object side 12, and the side of the seventh lens L7 away from the sixth lens L6 is the image side 13. In the optical system provided in this embodiment, from the object side 12 to the image side 13, there are successively the aperture stop STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the infrared filter element IRCF. Among them, the object side surface and / or the image side surface of the seventh lens L7 is provided with an inflection point.

[0168] The first lens L1 has a positive refractive power and is made of plastic. Its object side surface S1 is convex at the optical axis and at the circumference, its image side surface S2 is concave at the optical axis, and its image side surface S2 is convex at the circumference, and they are all aspherical surfaces.

[0169] The second lens L2 has a positive refractive power and is made of plastic. Its object side surface S3 is concave at the optical axis and at the circumference, its image side surface S4 is convex at the optical axis and at the circumference, and they are all aspherical surfaces.

[0170] The third lens L3 has a negative refractive power and is made of plastic. Its object side surface S5 is concave at the optical axis and at the circumference, its image side surface S6 is convex at the optical axis and at the circumference, and they are all aspherical surfaces.

[0171] The fourth lens L4 has a negative refractive power and is made of plastic. Its object side surface S7 is concave at the optical axis and at the circumference, its image side surface S8 is concave at the optical axis, and its image side surface S8 is convex at the circumference, and they are all aspherical surfaces.

[0172] The fifth lens L5 has a positive refractive power and is made of plastic. Its object side surface S9 is concave at the optical axis and at the circumference, its image side surface S10 is convex at the optical axis and at the circumference, and they are all aspherical surfaces.

[0173] The sixth lens L6 has a negative refractive power and is made of plastic. Its object side surface S11 is concave at the optical axis and at the circumference, its image side surface S12 is concave at the optical axis, and its image side surface S12 is convex at the circumference, and they are all aspherical surfaces.

[0174] The seventh lens L7 has a positive refractive power and is made of plastic. Its object side surface S13 is convex at the optical axis and at the circumference, its image side surface S14 is concave at the optical axis, and its image side surface S14 is convex at the circumference, and they are all aspherical surfaces.

[0175] The aperture stop STO can be located between the object side of the optical system and the seventh lens. In this embodiment, the aperture stop STO is arranged on the side of the first lens L1 away from the second lens L2 to control the amount of incident light.

[0176] The infrared filter element IRCF is disposed behind the seventh lens L7, and includes an object side surface S15 and an image side surface S16. The infrared filter element IRCF is used to filter out infrared light, so that the light incident on the imaging surface is visible light. The wavelength of the visible light is 380nm - 780nm, and the material of the infrared filter element IRCF is glass.

[0177] The imaging surface S17 is the surface where the image of the light of the object to be photographed is formed after passing through the optical system.

[0178] Table 6a shows the characteristic table of the optical system of this embodiment.

[0179] Table 6a

[0180]

[0181]

[0182] Among them, f is the effective focal length of the optical system, FNO is the aperture number of the optical system, FOV is the field of view angle in the diagonal direction of the optical system, and 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.

[0183] Table 6b gives the higher-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, S11, S12, S13, S14 in the sixth embodiment.

[0184] Table 6b

[0185]

[0186] Figure 13 Shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the sixth embodiment. Among them, the longitudinal spherical aberration curve represents the deviation of the convergence points of light rays of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the curvature of the meridional image plane and the sagittal image plane; the distortion curve represents the distortion magnitude values corresponding to different field of view angles. According to Figure 13 It can be seen that the optical system given in the sixth embodiment can achieve good imaging quality.

[0187] Embodiment Seven

[0188] As Figure 14As shown, the straight line 11 represents the optical axis. The side of the first lens L1 away from the second lens L2 is the object side 12, and the side of the seventh lens L7 away from the sixth lens L6 is the image side 13. In the optical system provided in this embodiment, from the object side 12 to the image side 13, there are successively the aperture stop STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the infrared filter element IRCF. Among them, an inflection point is provided on the object side surface and / or the image side surface of the seventh lens L7.

[0189] The first lens L1 has a positive refractive power and is made of plastic. Its object side surface S1 is convex at the optical axis and at the circumference, its image side surface S2 is concave at the optical axis and convex at the circumference, and both are aspherical surfaces.

[0190] The second lens L2 has a positive refractive power and is made of plastic. Its object side surface S3 is concave at the optical axis and at the circumference, its image side surface S4 is convex at the optical axis and at the circumference, and both are aspherical surfaces.

[0191] The third lens L3 has a negative refractive power and is made of plastic. Its object side surface S5 is concave at the optical axis and at the circumference, its image side surface S6 is convex at the optical axis and at the circumference, and both are aspherical surfaces.

[0192] The fourth lens L4 has a negative refractive power and is made of plastic. Its object side surface S7 is concave at the optical axis and at the circumference, its image side surface S8 is convex at the optical axis and at the circumference, and both are aspherical surfaces.

[0193] The fifth lens L5 has a positive refractive power and is made of plastic. Its object side surface S9 is concave at the optical axis and at the circumference, its image side surface S10 is convex at the optical axis and at the circumference, and both are aspherical surfaces.

[0194] The sixth lens L6 has a negative refractive power and is made of plastic. Its object side surface S11 is concave at the optical axis and at the circumference, its image side surface S12 is concave at the optical axis and convex at the circumference, and both are aspherical surfaces.

[0195] The seventh lens L7 has a positive refractive power and is made of plastic. Its object side surface S13 is convex at the optical axis and concave at the circumference, its image side surface S14 is concave at the optical axis and convex at the circumference, and both are aspherical surfaces.

[0196] The aperture stop STO can be located between the object side of the optical system and the seventh lens. In this embodiment, the aperture stop STO is arranged on the side of the first lens L1 away from the second lens L2 and is used to control the amount of incident light.

[0197] The infrared filter element IRCF is disposed behind the seventh lens L7 and includes an object side surface S15 and an image side surface S16. The infrared filter element IRCF is used to filter out infrared light so that the light incident on the imaging surface is visible light with a wavelength of 380 nm - 780 nm. The material of the infrared filter element IRCF is glass.

[0198] The imaging surface S17 is the surface where the image of the light of the object to be photographed is formed after passing through the optical system.

[0199] Table 7a shows the characteristic table of the optical system of this embodiment.

[0200] Table 7a

[0201]

[0202]

[0203] Among them, f is the effective focal length of the optical system, FNO is the f-number of the optical system, FOV is the field of view angle in the diagonal direction of the optical system, and 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.

[0204] Table 7b gives the higher-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for the aspherical mirror surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, S14 in the seventh embodiment.

[0205] Table 7b

[0206]

[0207] Figure 15 Shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the seventh embodiment. Among them, the longitudinal spherical aberration curve represents the deviation of the convergence points of light rays with different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the curvature of the meridional image plane and the sagittal image plane; the distortion curve represents the distortion magnitude values corresponding to different field of view angles. According to Figure 15 It can be seen that the optical system given in the seventh embodiment can achieve good imaging quality.

[0208] Embodiment Eight

[0209] As Figure 16As shown in the figure, the straight line 11 represents the optical axis. The side of the first lens L1 away from the second lens L2 is the object side 12, and the side of the seventh lens L7 away from the sixth lens L6 is the image side 13. In the optical system provided in this embodiment, from the object side 12 to the image side 13, there are successively the aperture stop STO, the first lens L1, the second lens L2, the third lens L3, the fourth lens L4, the fifth lens L5, the sixth lens L6, the seventh lens L7, and the infrared filter element IRCF. Among them, the object side surface and / or the image side surface of the seventh lens L7 is provided with an inflection point.

[0210] The first lens L1 has a positive refractive power and is made of plastic. Its object side surface S1 is convex at the optical axis and at the circumference, and its image side surface S2 is concave at the optical axis and at the circumference, and both are aspherical surfaces.

[0211] The second lens L2 has a positive refractive power and is made of plastic. Its object side surface S3 is convex at the optical axis and at the circumference, and its image side surface S4 is convex at the optical axis and at the circumference, and both are aspherical surfaces.

[0212] The third lens L3 has a negative refractive power and is made of plastic. Its object side surface S5 is concave at the optical axis and at the circumference, and its image side surface S6 is convex at the optical axis and at the circumference, and both are aspherical surfaces.

[0213] The fourth lens L4 has a negative refractive power and is made of plastic. Its object side surface S7 is convex at the optical axis and concave at the circumference, and its image side surface S8 is concave at the optical axis and at the circumference, and both are aspherical surfaces.

[0214] The fifth lens L5 has a positive refractive power and is made of plastic. Its object side surface S9 is concave at the optical axis and at the circumference, and its image side surface S10 is convex at the optical axis and at the circumference, and both are aspherical surfaces.

[0215] The sixth lens L6 has a negative refractive power and is made of plastic. Its object side surface S11 is concave at the optical axis and at the circumference, its image side surface S12 is concave at the optical axis and convex at the circumference, and both are aspherical surfaces.

[0216] The seventh lens L7 has a negative refractive power and is made of plastic. Its object side surface S13 is convex at the optical axis and concave at the circumference, its image side surface S14 is concave at the optical axis and convex at the circumference, and both are aspherical surfaces.

[0217] The aperture stop STO can be located between the object side of the optical system and the seventh lens. In this embodiment, the aperture stop STO is arranged on the side of the first lens L1 away from the second lens L2 and is used to control the amount of incident light.

[0218] The infrared filter element IRCF is disposed behind the seventh lens L7 and includes an object side surface S15 and an image side surface S16. The infrared filter element IRCF is used to filter out infrared light so that the light incident on the imaging surface is visible light, and the wavelength of the visible light is 380 nm - 780 nm. The material of the infrared filter element IRCF is glass.

[0219] The imaging surface S17 is the surface where the image of the light of the object to be photographed is formed after passing through the optical system.

[0220] Table 8a shows the characteristic table of the optical system of this embodiment.

[0221] Table 8a

[0222]

[0223]

[0224] Among them, f is the effective focal length of the optical system, FNO is the f-number of the optical system, FOV is the field of view angle in the diagonal direction of the optical system, and 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.

[0225] Table 8b gives the higher-order term coefficients A4, A6, A8, A10, A12, A14, A16, A18, and A20 that can be used for the aspherical mirror surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11, S12, S13, and S14 in the eighth embodiment.

[0226] Table 8b

[0227]

[0228] Figure 17 Shows the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the eighth embodiment. Among them, the longitudinal spherical aberration curve represents the deviation of the convergence points of light rays of different wavelengths after passing through the lenses of the optical system; the astigmatism curve represents the curvature of the meridional image plane and the sagittal image plane; the distortion curve represents the distortion magnitude values corresponding to different field of view angles. According to Figure 17 It can be seen that the optical system given in the eighth embodiment can achieve good imaging quality.

[0229] Table 9 shows the values of tanω / f, f / f5, f1 / f, TTL / EPD, f12 / f34, n4, FNO / ImgH, f / CT5, and Y2 / Y1 + Y3 / Y1 + Y4 / Y1 of the optical systems of the first embodiment to the eighth embodiment.

[0230] Table 9

[0231]

[0232] As can be seen from Table 9, each embodiment can satisfy: tanω / f > 0.21mm -1 , 0.5 < f / f5 < 1.4, 1 < f1 / f < 1.6, TTL / EPD < 2.8, f12 / f34 > -0.54, 1.66 < n4 < 1.69, FNO / ImgH ≤ 0.55mm -1 , 3.7 < f / CT5 < 5.1, Y2 / Y1 + Y3 / Y1 + Y4 / Y1 < 3.1.

[0233] The above is the preferred embodiment of the present application. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present application, several improvements and refinements can be made, and these improvements and refinements are also regarded as the protection scope of the present application.

Claims

1. An optical system, characterized in that, it has a total of seven lenses with refractive power, arranged in order from the object side to the image side as follows: The first lens, having a positive refractive power, the object side surface of the first lens is convex at the optical axis, and the image side surface of the first lens is concave at the optical axis; The second lens, having refractive power, the image side surface of the second lens is convex at the optical axis; The third lens, having refractive power, the object side surface of the third lens is concave at the optical axis, and the image side surface of the third lens is convex at the optical axis; The fourth lens, having refractive power; The fifth lens, having a positive refractive power, the object side surface of the fifth lens is concave at the optical axis, and the image side surface of the fifth lens is convex at the optical axis; The sixth lens, having refractive power, the image side surface of the sixth lens is concave at the optical axis; The seventh lens, having refractive power, the object side surface of the seventh lens is convex at the optical axis, the image side surface of the seventh lens is concave at the optical axis, and an anastigmatism point is provided on the object side surface and / or the image side surface of the seventh lens; The optical system satisfies the following conditional expressions: tanω / f > 0.21 mm -1 , 2.95 ≤ Y2 / Y1 + Y3 / Y1 + Y4 / Y1 < 3.1, 0.5 < f / f5 < 1.4, where, tanω is the tangent value of half of the maximum field of view angle of the optical system, f is the effective focal length of the optical system, Y1 is the maximum optical effective radius of the object side surface of the first lens, Y2 is the maximum optical effective radius of the object side surface of the second lens, Y3 is the maximum optical effective radius of the object side surface of the third lens, Y4 is the maximum optical effective radius of the object side surface of the fourth lens, and f5 is the focal length of the fifth lens.

2. The optical system according to claim 1, characterized in that, the optical system satisfies the conditional expression: 1 < f1 / f < 1.6, where, f1 is the focal length of the first lens.

3. The optical system according to claim 1, characterized in that, the optical system satisfies the conditional expression: f12 / f34 > -0.54, where, f12 is the combined focal length of the first lens and the second lens, and f34 is the combined focal length of the third lens and the fourth lens.

4. The optical system according to claim 1, characterized in that, the optical system satisfies the conditional expression: 1.66<n4<1.69， where, n4 is the refractive index of the fourth lens.

5. The optical system according to claim 1, characterized in that, the optical system satisfies the conditional expression: 3.7 < f / CT5 < 5.1, where, CT5 is the thickness of the fifth lens on the optical axis.

6. The optical system according to claim 1, characterized in that, the optical system satisfies the conditional expression: 1.372 ≤ TTL / EPD < 2.8, where, TTL is the distance on the optical axis from the object side surface of the first lens to the imaging surface of the optical system, and EPD is the entrance pupil diameter of the optical system.

7. The optical system according to claim 1, characterized in that, the optical system satisfies the conditional expression: FNO / ImgH ≤ 0.55 mm -1 , where, FNO is the f-number of the optical system, and ImgH is half of the diagonal length of the effective pixel region on the imaging surface of the optical system.

8. A lens module, characterized in that, it includes a photosensitive element and the optical system according to any one of claims 1 to 7, and the photosensitive element is located on the image side of the optical system.

9. A terminal device, characterized in that, it includes the lens module according to claim 8.

Images