Optical systems, lens modules and terminal equipment

Abstract

Embodiments of the present application disclose an optical system, a lens module, and a terminal device. The optical system includes a first lens with positive refractive power, a second lens, a third lens, and a fourth lens with negative refractive power, and a fifth lens and a sixth lens with refractive power. The object side surface of the first lens is convex at the optical axis, the image side surface of the second lens is concave at the optical axis, the object side surface of the third lens is convex at the optical axis, the image side surface of the third lens is concave at the optical axis, and the image side surface of the fourth lens is concave at the optical axis. The optical system satisfies the following conditional formula: 1 < ftLtl4 / ftGtl4 < 1.5; ftLtl4 and ftGtl4 are respectively the longest and shortest distances from the object side surface of the fourth lens to the image side surface of the fourth lens in the direction parallel to the optical axis. By reasonably configuring the refractive powers of the first lens to the sixth lens and the surface types of the first lens to the fourth lens, the optical system has the characteristics of a long focal length and good imaging quality, and can achieve high-definition long-distance shooting.

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] With the wide application of electronic products such as mobile phones, tablet computers, drones, and computers in life, various technological improvements are emerging in an endless stream. Among them, the improvement and innovation of the shooting effect of the camera lens in new electronic products have become the focus of people's attention.

[0003] Currently, with the increasing demand for long-distance shooting, the camera lens needs to have a long focal length, but it is prone to the problem of field curvature and it is difficult to guarantee the overall imaging quality, resulting in poor long-distance photography effects.

[0004] Therefore, how to achieve long-distance shooting and high-definition shooting and avoid the problem of field curvature, so that the scene with a relatively large object distance can be clearly imaged on the imaging surface should be the research and development direction of the industry. Summary of the Invention

[0005] The embodiments of this application provide an optical system, a lens module and a terminal device. The optical system solves the problem of poor imaging quality in long-distance shooting and can achieve high-definition long-distance shooting.

[0006] In a first aspect, the embodiments of this application provide an optical system. The optical system includes multiple lenses. The multiple lenses include a first lens arranged in sequence from the object side to the image side, having a positive refractive power, and the object side surface of the first lens is convex at the optical axis; a second lens, having a negative refractive power, and the image side surface of the second lens is concave at the optical axis; a third lens, having a negative refractive power, and the object side surface of the third lens is convex at the optical axis, and the image side surface of the third lens is concave at the optical axis; a fourth lens, having a negative refractive power, and the image side surface of the fourth lens is concave at the optical axis; a fifth lens, having a refractive power; a sixth lens, having a refractive power. The optical system satisfies the following conditional formula: 1 < ftLtl4 / ftGtl4 < 1.5; ftLtl4 is the longest distance from the object side surface of the fourth lens to the image side surface of the fourth lens in the direction parallel to the optical axis, and ftGtl4 is the shortest distance from the object side surface of the fourth lens to the image side surface of the fourth lens in the direction parallel to the optical axis.

[0007] By reasonably configuring the refractive powers of the first lens to the sixth lens and the surface shapes of the first lens, the second lens, the third lens, and the fourth lens in the optical system, the optical system has the characteristics of a long focal length and good imaging quality, enabling high-definition long-distance shooting. At the same time, setting 1 < ftLtl4 / ftGtl4 < 1.5 can effectively balance the optical path difference of the optical system, achieve the function of correcting field curvature, avoid distortion around the image, make the imaging effect closer to the object itself, and make the captured image have high picture quality, high resolution, and high clarity.

[0008] In one implementation, the optical system satisfies the conditional formula: 0.5 < DL1 / Imgh < 1; DL1 is the effective aperture of the first lens, and Imgh is half of the diagonal length of the effective pixel area on the imaging surface of the optical system. The aperture size of the first lens in the optical system determines the amount of light passing through the entire optical system, and the size of the photosensitive surface determines the clarity and pixel size of the entire optical system's image. Only when the two are reasonably coordinated can sufficient light passing through be ensured to guarantee the clarity of the captured image. If DL1 / Imgh > 1, it will cause overexposure and too high light brightness, affecting the image quality. If DL1 / Imgh < 0.5, it will cause insufficient light passing through and relatively insufficient light brightness, resulting in a decrease in image clarity.

[0009] In one implementation, the optical system satisfies the conditional formula: 2 < f / f1 < 3; f is the effective focal length of the optical system, and f1 is the focal length of the first lens. The first lens provides all the optical information of the optical system from the object space to the image space. The focal length of the first lens determines the acquisition of light information in the object space by the optical system. If f / f1 ≥ 3, it will cause an increase in system sensitivity, difficulty in processing technology, and an increase in the difficulty of correcting aberrations generated by the first lens, making it difficult to meet the shooting requirements. If f / f1 ≤ 2, the focal length ratio of the first lens to the optical system is inappropriate, and the aberrations generated by the first lens cannot be corrected.

[0010] In one implementation, the optical system satisfies the conditional formula: -0.5 < f1 / f2 < -0.2; f1 is the focal length of the first lens, and f2 is the focal length of the second lens. The first lens provides positive refractive power to converge light rays, facilitating the convergence of light rays in the object space. The second lens provides negative refractive power to correct the position chromatic aberration brought by the first lens. The combination of the first lens with positive refractive power and the second lens with negative refractive power can effectively correct the position chromatic aberration and improve imaging clarity.

[0011] In one embodiment, the optical system satisfies the conditional formula: 0.05 < airL3 / TTL < 0.3; airL3 is the distance on the optical axis from the image side of the third lens to the object side of the fourth lens, and TTL is the distance on the optical axis from the object side of the first lens to the imaging surface of the optical system. By defining a suitable range of airL3 / TTL, the assembly sensitivity of the optical system can be reduced and the assembly yield can be improved. If airL3 / TTL > 0.3, the system will be too long. If airL3 / TTL < 0.05, the system sensitivity will increase and the production yield will decrease.

[0012] In one embodiment, the optical system satisfies the conditional formula: 1 mm < (R5*R6) / (R5+R6) < 4.5 mm; R5 is the radius of curvature at the optical axis of the object side of the third lens, and R6 is the radius of curvature at the optical axis of the image side of the third lens. By defining a suitable range of (R5*R6) / (R5+R6), the optical path difference between the marginal rays and paraxial rays of the optical system can be reasonably balanced, the field curvature and astigmatism can be reasonably corrected, the system sensitivity can be reduced, and the assembly stability can be improved.

[0013] In one embodiment, the optical system satisfies the conditional formula: FBL / TTL > 0.1; FBL is the distance on the optical axis from the intersection of the image side of the sixth lens and the optical axis to the imaging surface, and TTL is the distance on the optical axis from the object side of the first lens to the imaging surface of the optical system. By defining a suitable range of FBL / TTL, while meeting miniaturization requirements, it can ensure that the system has sufficient focusing range, improve the assembly yield of the optical system, and at the same time ensure that the depth of focus of the optical system is relatively large, enabling more depth information of the object space to be obtained.

[0014] In one embodiment, the optical system further includes an aperture, and the aperture is located on the object side of the first lens or between two adjacent lenses. The optical system satisfies the conditional formula: 0.5 < DL / Imgh < 1; DL is the aperture diameter of the aperture 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. The aperture size of the aperture of the optical system determines the amount of light passing through the entire optical system, and the size of the photosensitive surface determines the clarity and pixel size of the entire optical system image. Only by reasonably coordinating the two can sufficient light passing amount be ensured and the clarity of the captured image be guaranteed. If DL / Imgh > 1, overexposure will occur, the light brightness will be too high, affecting the image quality. If DL / Imgh < 0.5, the light passing amount will be insufficient, the relative brightness of the light will not be enough, and the image sensitivity will decrease.

[0015] In one embodiment, the optical system further includes an aperture, which is located on the object side of the first lens or between two adjacent lenses. The optical system satisfies the conditional formula: 1.5 < TTL / DL < 2.2; 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, and DL is the aperture diameter of the aperture of the optical system. By defining an appropriate range of TTL / DL, the optical system can meet the design requirements of miniaturization and provide the light transmission amount required for the optical system to take pictures, achieving a high-quality and high-clarity shooting effect. If TTL / DL < 1.5, the miniaturization design can be satisfied, but the light transmission aperture will be too large, and marginal rays will enter the optical system, reducing the imaging quality. If TTL / DL > 2.2, the miniaturization design can be satisfied, but the light transmission aperture of the aperture will be too small to meet the light transmission amount required by the system.

[0016] In one embodiment, the optical system satisfies the conditional formula: 0.7 < TTL / f < 1; 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, and f is the effective focal length of the optical system. By defining an appropriate range of TTL / f, not only can the miniaturization of the optical system be achieved, but also better convergence of light rays on the imaging surface can be ensured. If TTL / f ≤ 0.7, the length of the optical system is too short, which will increase the sensitivity of the system and is not conducive to the convergence of light rays on the imaging surface. If TTL / f ≥ 1, the length of the optical system is too long, which will cause the angle of the chief ray entering the imaging surface to be too large, and marginal rays cannot enter the imaging surface, resulting in incomplete imaging information.

[0017] 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.

[0018] In a third aspect, the present application provides a terminal device, including the lens module described above.

[0019] By reasonably configuring the refractive power of the first lens to the sixth lens and the surface types of the first lens, the second lens, the third lens, and the fourth lens in the optical system, the optical system has the characteristics of a long focal length and good imaging quality, and can achieve high-clarity long-distance shooting. At the same time, setting 1 < ftLtl4 / ftGtl4 < 1.5 can effectively balance the optical path difference of the optical system, achieve the function of correcting field curvature, avoid distortion around the image, make the imaging effect closer to the object itself, and make the captured image have a high picture quality, high resolution, and high clarity. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the background technology, the drawings required for use in the embodiments of the present application or the background technology will be described below.

[0021] Figure 1 is a schematic diagram of the optical system provided by this application applied in a terminal device;

[0022] Figure 2 is a schematic structural diagram of an optical system provided in the first embodiment of the present application;

[0023] Figure 3 1 are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the first embodiment;

[0024] Figure 4 is a schematic structural diagram of an optical system provided in a second embodiment of the present application;

[0025] Figure 5 1 and 2 are longitudinal spherical aberration curves, astigmatism curves, and distortion curves of the optical system of the second embodiment;

[0026] Figure 6 is a schematic structural diagram of an optical system provided in the third embodiment of the present application;

[0027] Figure 7 1. are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the third embodiment;

[0028] Figure 8 is a schematic structural diagram of an optical system provided in a fourth embodiment of the present application;

[0029] Figure 9 1 and 2 are longitudinal spherical aberration curves, astigmatism curves, and distortion curves of the optical system of the fourth embodiment;

[0030] Figure 10 is a schematic structural diagram of an optical system provided in a fifth embodiment of the present application;

[0031] Figure 11 1 and 2 are longitudinal spherical aberration curves, astigmatism curves, and distortion curves of the optical system of the fifth embodiment;

[0032] Figure 12 is a schematic structural diagram of an optical system provided in a sixth embodiment of the present application;

[0033] Figure 13 1 and 2 are longitudinal spherical aberration curves, astigmatism curves, and distortion curves of the optical system of the sixth embodiment;

[0034] Figure 14 is a schematic structural diagram of an optical system provided in the seventh embodiment of the present application;

[0035] Figure 157 are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the seventh embodiment;

[0036] Figure 16 is a schematic structural diagram of an optical system provided in an eighth embodiment of the present application;

[0037] Figure 17 1 and 2 are the longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the eighth embodiment. DETAILED DESCRIPTION

[0038] The embodiments of the present application are described below in conjunction with the drawings in the embodiments of the present application.

[0039] See Figure 1 The optical system involved in this application is applied to a lens module 20 in a terminal device 30. The terminal device 30 can be 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.

[0040] The present application provides a lens module, including a photosensitive element and an optical system provided in an embodiment of the present application. The photosensitive element is located on the image side of the optical system and is used to convert light that passes through the first lens to the sixth lens and is 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 a long focal length and good imaging quality, which can achieve high-definition long-range shooting.

[0041] This application also provides a terminal device including a lens module according to an embodiment of this application. The terminal device can be a mobile phone, tablet computer, drone, computer, etc. By installing the lens module in the terminal device, the terminal device has a long focal length and good imaging quality, enabling high-definition long-range photography.

[0042] The present application provides an optical system including six lenses, which are sequentially distributed from the object side to the image side as a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens.

[0043] Specifically, the surface shape and refractive power of the six lenses are as follows:

[0044] The first lens, having a positive refractive power, the object side surface of the first lens is convex at the optical axis; the second lens, having a negative refractive power, the image side surface of the second lens is concave at the optical axis; the third lens, having a negative refractive power, the object side surface of the third lens is convex at the optical axis, and the image side surface of the third lens is concave at the optical axis; the fourth lens, having a negative refractive power, the image side surface of the fourth lens is concave at the optical axis; the fifth lens, having a refractive power; the sixth lens, having a refractive power.

[0045] The optical system satisfies the following conditional formula: 1 < ftLtl4 / ftGtl4 < 1.5; ftLtl4 is the longest distance from the object side surface of the fourth lens to the image side surface of the fourth lens in the direction parallel to the optical axis, and ftGtl4 is the shortest distance from the object side surface of the fourth lens to the image side surface of the fourth lens in the direction parallel to the optical axis.

[0046] The refractive powers of the first lens to the sixth lens in the optical system and the surface shapes of the first lens, the second lens, the third lens and the fourth lens are reasonably arranged, so that the optical system has the characteristics of a long focal length and has good imaging quality, can achieve high-definition long-distance shooting. At the same time, setting 1 < ftLtl4 / ftGtl4 < 1.5 can effectively balance the optical path difference of the optical system, realize the function of correcting field curvature, avoid distortion around the image, make the imaging effect closer to the object itself, and make the captured picture have high picture quality, high resolution and high definition.

[0047] In one embodiment, the optical system satisfies the conditional formula: 0.5 < DL1 / Imgh < 1; DL1 is the effective aperture of the first lens, and Imgh is half of the diagonal length of the effective pixel area on the imaging surface of the optical system. The aperture size of the first lens in the optical system determines the light passing amount of the entire optical system, and the size of the photosensitive surface determines the picture clarity and pixel size of the entire optical system. Only by reasonable cooperation of the two can ensure sufficient light passing amount and ensure the clarity of the captured image. If DL1 / Imgh > 1, it will cause overexposure and too high light brightness, affecting the picture quality. If DL1 / Imgh < 0.5, it will cause insufficient light passing amount and insufficient relative brightness of light, resulting in a decrease in picture clarity.

[0048] In one embodiment, the optical system satisfies the conditional formula: 2 < f / f1 < 3; f is the effective focal length of the optical system, and f1 is the focal length of the first lens. The first lens provides all the optical information of the optical system from the object space to the image space. The focal length of the first lens determines the acquisition of the optical information of the object space by the optical system. If f / f1 ≥ 3, it will cause an increase in system sensitivity, difficulty in processing technology, and an increase in the difficulty of correcting the aberration generated by the first lens, making it difficult to meet the shooting requirements. If f / f1 ≤ 2, the focal length ratio of the first lens to the optical system is inappropriate, and the aberration generated by the first lens cannot be corrected.

[0049] In one embodiment, the optical system satisfies the conditional formula: -0.5 < f1 / f2 < -0.2; f1 is the focal length of the first lens, and f2 is the focal length of the second lens. The first lens provides positive refractive power to converge light rays, which is beneficial for converging the light rays in the object space. The second lens provides negative refractive power and can correct the longitudinal chromatic aberration brought by the first lens. The combination of the first lens with positive refractive power and the second lens with negative refractive power can effectively correct the longitudinal chromatic aberration and improve the imaging clarity.

[0050] In one embodiment, the optical system satisfies the conditional formula: 0.05 < airL3 / TTL < 0.3; airL3 is the distance on the optical axis from the image side of the third lens to the object side of the fourth lens, and TTL is the distance on the optical axis from the object side of the first lens to the imaging surface of the optical system. By limiting the appropriate range of airL3 / TTL, the assembly sensitivity of the optical system can be reduced, and the assembly yield can be improved. If airL3 / TTL > 0.3, the system will be too long. If airL3 / TTL < 0.05, the system sensitivity will increase, resulting in a decrease in production yield.

[0051] In one embodiment, the optical system satisfies the conditional formula: 1mm < (R5*R6) / (R5+R6) < 4.5mm; R5 is the radius of curvature of the object side of the third lens on the optical axis, and R6 is the radius of curvature of the image side of the third lens on the optical axis. By limiting the appropriate range of (R5*R6) / (R5+R6), the optical path difference between the marginal rays and the paraxial rays of the optical system can be reasonably balanced, the field curvature and astigmatism can be reasonably corrected, and at the same time, the system sensitivity can be reduced, and the assembly stability can be improved.

[0052] In one embodiment, the optical system satisfies the conditional formula: FBL / TTL > 0.1; FBL is the distance from the intersection point of the image side surface of the sixth lens and the optical axis to the imaging surface on the optical axis, 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. By defining the appropriate range of FBL / TTL, while meeting the miniaturization requirement, it can ensure that the system has sufficient focusing range, improve the assembly yield of the optical system, and at the same time ensure that the depth of focus of the optical system is relatively large, enabling the acquisition of more depth information on the object side.

[0053] In one embodiment, the optical system further includes an aperture stop, and the aperture stop is located on the object side of the first lens or between two adjacent lenses. The optical system satisfies the conditional formula: 0.5 < DL / Imgh < 1; DL is the aperture of the aperture stop 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. The aperture size of the aperture stop of the optical system determines the amount of light passing through the entire optical system, and the size of the photosensitive surface determines the clarity and pixel size of the entire optical system image. Only when the two are reasonably coordinated can sufficient light passing amount be ensured to guarantee the clarity of the captured image. If DL / Imgh > 1, it will cause overexposure and too high light brightness, affecting the image quality. If DL / Imgh < 0.5, it will cause insufficient light passing amount, relatively low light brightness, and a decrease in the image sensitivity of the image.

[0054] In one embodiment, the optical system further includes an aperture stop, and the aperture stop is located on the object side of the first lens or between two adjacent lenses. The optical system satisfies the conditional formula: 1.5 < TTL / DL < 2.2; 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, and DL is the aperture of the aperture stop of the optical system. By defining the appropriate range of TTL / DL, the optical system can meet the design requirements of miniaturization and provide the light passing amount required for the optical system to take pictures, achieving high-image-quality and high-clarity shooting effects. If TTL / DL < 1.5, it can meet the miniaturization design, but it will cause too large an aperture diameter, allowing marginal light rays to enter the optical system and reducing the imaging quality. If TTL / DL > 2.2, it can meet the miniaturization design, but it will cause too small an aperture diameter of the aperture stop and cannot meet the light passing amount required by the system.

[0055] In one embodiment, the optical system satisfies the conditional formula: 0.7 < TTL / f < 1; TTL is the distance on the optical axis from the object side of the first lens to the imaging surface of the optical system, and f is the effective focal length of the optical system. By defining a suitable range of TTL / f, not only can the miniaturization of the optical system be achieved, but also better convergence of light rays on the imaging surface can be ensured. If TTL / f ≤ 0.7, the length of the optical system is too short, which will increase the sensitivity of the system and is not conducive to the convergence of light rays on the imaging surface. If TTL / f ≥ 1, the length of the optical system is too long, which will cause the angle of the chief ray entering the imaging surface to be too large, and the marginal rays cannot enter the imaging surface, resulting in incomplete imaging information.

[0056] By defining the above various parameters, the optical system has good imaging quality. For example, preferably: the value of ftLtl4 / ftGtl4 can be 1.04 or 1.26 or 1.24, etc., the value of DL1 / Imgh can be 0.81 or 0.70 or 0.69, etc., the value of f / f1 can be 2.31 or 2.47 or 2.39, etc., the value of f1 / f2 can be -0.45 or -0.41 or -0.39, etc., and the value of airL3 / TTL can be 0.18 or 0.17 or 0.16, etc.

[0057] 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:

[0058]

[0059] Where, 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.

[0060] The following details the present application through eight specific embodiments.

[0061] Embodiment 1

[0062] 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 sixth lens L6 away from the fifth lens L5 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 diaphragm 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, and an infrared filter element IRCF.

[0063] The first lens L1 has 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 convex at the optical axis and at the circumference, and both are aspherical.

[0064] The second lens L2 has negative refractive power and is made of plastic. Its object-side surface S3 is concave at the optical axis and convex at the circumference. Its image-side surface S4 is concave at the optical axis and at the circumference, and both are aspherical.

[0065] The third lens L3 has negative refractive power and is made of plastic. Its object-side surface S5 is convex at the optical axis and at the circumference, and its image-side surface S6 is concave at the optical axis and at the circumference, and both are aspherical.

[0066] The fourth lens L4 has negative refractive power and is made of plastic. Its object-side surface S7 is concave at the optical axis and at the circumference, and its image-side surface S8 is concave at the optical axis and at the circumference, and both are aspherical.

[0067] The fifth lens L5 has 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.

[0068] The sixth lens L6 has negative refractive power and is made of plastic. Its object-side surface S11 is concave at the optical axis and at the circumference, and its image-side surface S12 is convex at the optical axis and at the circumference, and both are aspherical.

[0069] The aperture STO may be located between the object side of the optical system and the sixth lens. In this embodiment, the aperture STO is disposed on a side of the first lens L1 away from the second lens L2 for controlling the amount of incoming light.

[0070] The infrared filter element IRCF is arranged after the sixth lens L6, and includes an object-side surface S13 and an image-side surface S14. 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 visible light is 380nm-780nm. The material of the infrared filter element IRCF is glass.

[0071] The imaging plane S15 is the plane where the image of the object is formed after the light passes through the optical system.

[0072] Table 1a shows the characteristics of the optical system of this embodiment, wherein the curvature radius in this embodiment is the curvature radius of each lens at the optical axis.

[0073] Table 1a

[0074]

[0075] Wherein, f is the effective focal length of the optical system, FNO is the aperture number of the optical system, FOV is the diagonal field of view of the optical system, and TTL is the distance from the object side of the first lens to the imaging plane of the optical system on the optical axis.

[0076] Table 1b gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of the aspheric mirror surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11 and S12 that can be used in the first embodiment.

[0077] Table 1b

[0078]

[0079]

[0080] Figure 3 The 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 focal point of light of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the meridional image curvature and sagittal image curvature; and the distortion curve represents the distortion value corresponding to different field angles. Figure 3 It can be seen that the optical system provided in the first embodiment can achieve good imaging quality.

[0081] Example 2

[0082] like Figure 4 As shown, line 11 represents the optical axis. The side of first lens L1 distal to second lens L2 is object side 12, and the side of sixth lens L6 distal to fifth lens L5 is image side 13. In the optical system provided in this embodiment, from object side 12 to image side 13, are aperture stop STO, first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, and infrared filter IRCF.

[0083] The first lens L1 has 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 convex at the optical axis and at the circumference, and both are aspherical.

[0084] The second lens L2 has negative 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 concave at the optical axis and at the circumference, and both are aspherical.

[0085] The third lens L3 has negative refractive power and is made of plastic. Its object-side surface S5 is convex at the optical axis and at the circumference, and its image-side surface S6 is concave at the optical axis and at the circumference, and both are aspherical.

[0086] The fourth lens L4 has negative refractive power and is made of plastic. Its object-side surface S7 is concave at the optical axis and at the circumference, and its image-side surface S8 is concave at the optical axis and at the circumference, and both are aspherical.

[0087] The fifth lens L5 has 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.

[0088] The sixth lens L6 has negative refractive power and is made of plastic. Its object-side surface S11 is concave at the optical axis and at the circumference, and its image-side surface S12 is convex at the optical axis and at the circumference, and both are aspherical.

[0089] The aperture STO may be located between the object side of the optical system and the sixth lens. In this embodiment, the aperture STO is disposed on a side of the first lens L1 away from the second lens L2 for controlling the amount of incoming light.

[0090] The infrared filter element IRCF is arranged after the sixth lens L6, and includes an object-side surface S13 and an image-side surface S14. 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 visible light is 380nm-780nm. The material of the infrared filter element IRCF is glass.

[0091] The imaging plane S15 is the plane where the image of the object is formed after the light passes through the optical system.

[0092] Table 2a shows the characteristics of the optical system of this embodiment, wherein the curvature radius in this embodiment is the curvature radius of each lens at the optical axis.

[0093] Table 2a

[0094]

[0095]

[0096] Wherein, f is the effective focal length of the optical system, FNO is the aperture number of the optical system, FOV is the diagonal field of view of the optical system, and TTL is the distance from the object side of the first lens to the imaging plane of the optical system on the optical axis.

[0097] Table 2b gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of the aspheric mirror surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11 and S12 that can be used in the second embodiment.

[0098] Table 2b

[0099]

[0100]

[0101] Figure 5 The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the second embodiment are shown. Among them, the longitudinal spherical aberration curve represents the deviation of the focal point of light of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the meridional image curvature and sagittal image curvature; and the distortion curve represents the distortion value corresponding to different field angles. Figure 5 It can be seen that the optical system provided in the second embodiment can achieve good imaging quality.

[0102] Example 3

[0103] like Figure 6 As shown, line 11 represents the optical axis. The side of first lens L1 distal to second lens L2 is object side 12, and the side of sixth lens L6 distal to fifth lens L5 is image side 13. In the optical system provided in this embodiment, from object side 12 to image side 13, are aperture stop STO, first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, and infrared filter IRCF.

[0104] The first lens L1 has 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 convex at the optical axis and at the circumference, and both are aspherical.

[0105] The second lens L2 has negative 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 concave at the optical axis and at the circumference, and both are aspherical.

[0106] The third lens L3 has negative refractive power and is made of plastic. Its object-side surface S5 is convex at the optical axis and at the circumference, and its image-side surface S6 is concave at the optical axis and at the circumference, and both are aspherical.

[0107] The fourth lens L4 has negative refractive power and is made of plastic. Its object-side surface S7 is concave at the optical axis and at the circumference, and its image-side surface S8 is concave at the optical axis and at the circumference, and both are aspherical.

[0108] The fifth lens L5 has positive refractive power and is made of plastic. Its object-side surface S9 is convex at the optical axis and concave at the circumference. Its image-side surface S10 is convex at the optical axis and at the circumference, and both are aspherical.

[0109] The sixth lens L6 has negative refractive power and is made of plastic. Its object-side surface S11 is concave at the optical axis and at the circumference, and its image-side surface S12 is convex at the optical axis and at the circumference, and both are aspherical.

[0110] The aperture STO may be located between the object side of the optical system and the sixth lens. In this embodiment, the aperture STO is disposed on a side of the first lens L1 away from the second lens L2 for controlling the amount of incoming light.

[0111] The infrared filter element IRCF is arranged after the sixth lens L6, and includes an object-side surface S13 and an image-side surface S14. 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 visible light is 380nm-780nm. The material of the infrared filter element IRCF is glass.

[0112] The imaging plane S15 is the plane where the image of the object is formed after the light passes through the optical system.

[0113] Table 3a shows the characteristics of the optical system of this embodiment, wherein the curvature radius in this embodiment is the curvature radius of each lens at the optical axis.

[0114] Table 3a

[0115]

[0116] Wherein, f is the effective focal length of the optical system, FNO is the aperture number of the optical system, FOV is the diagonal field of view of the optical system, and TTL is the distance from the object side of the first lens to the imaging plane of the optical system on the optical axis.

[0117] Table 3b gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of the aspheric mirror surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11 and S12 that can be used in the third embodiment.

[0118] Table 3b

[0119]

[0120]

[0121] Figure 7 The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the third embodiment are shown. Among them, the longitudinal spherical aberration curve represents the deviation of the focal point of light of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the meridional image curvature and sagittal image curvature; and the distortion curve represents the distortion value corresponding to different field angles. Figure 7It can be seen that the optical system provided in the third embodiment can achieve good imaging quality.

[0122] Example 4

[0123] like Figure 8 As shown, line 11 represents the optical axis. The side of first lens L1 distal to second lens L2 is object side 12, and the side of sixth lens L6 distal to fifth lens L5 is image side 13. In the optical system provided in this embodiment, from object side 12 to image side 13, are aperture stop STO, first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, and infrared filter IRCF.

[0124] The first lens L1 has 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 convex at the optical axis and at the circumference, and both are aspherical.

[0125] The second lens L2 has negative 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 concave at the optical axis and at the circumference, and both are aspherical.

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

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

[0128] The fifth lens L5 has 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.

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

[0130] The aperture STO may be located between the object side of the optical system and the sixth lens. In this embodiment, the aperture STO is disposed on a side of the first lens L1 away from the second lens L2 for controlling the amount of incoming light.

[0131] The infrared filter element IRCF is arranged after the sixth lens L6, and includes an object-side surface S13 and an image-side surface S14. 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 visible light is 380nm-780nm. The material of the infrared filter element IRCF is glass.

[0132] The imaging plane S15 is the plane where the image of the object is formed after the light passes through the optical system.

[0133] Table 4a shows the characteristics of the optical system of this embodiment, wherein the curvature radius in this embodiment is the curvature radius of each lens at the optical axis.

[0134] Table 4a

[0135]

[0136]

[0137] Wherein, f is the effective focal length of the optical system, FNO is the aperture number of the optical system, FOV is the diagonal field of view of the optical system, and TTL is the distance from the object side of the first lens to the imaging plane of the optical system on the optical axis.

[0138] Table 4b gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of the aspheric mirror surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11 and S12 that can be used in the fourth embodiment.

[0139] Table 4b

[0140]

[0141]

[0142] Figure 9 The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the fourth embodiment are shown. Among them, the longitudinal spherical aberration curve represents the deviation of the focal point of light of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the meridional image curvature and sagittal image curvature; and the distortion curve represents the distortion value corresponding to different field angles. Figure 9 It can be seen that the optical system provided in the fourth embodiment can achieve good imaging quality.

[0143] Example 5

[0144] like Figure 10As shown, line 11 represents the optical axis. The side of first lens L1 distal to second lens L2 is object side 12, and the side of sixth lens L6 distal to fifth lens L5 is image side 13. In the optical system provided in this embodiment, from object side 12 to image side 13, are aperture stop STO, first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, and infrared filter IRCF.

[0145] The first lens L1 has 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 convex at the optical axis and at the circumference, and both are aspherical.

[0146] The second lens L2 has negative 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 concave at the optical axis and at the circumference, and both are aspherical.

[0147] The third lens L3 has negative refractive power and is made of plastic. Its object-side surface S5 is convex at the optical axis and concave at the circumference. Its image-side surface S6 is concave at the optical axis and at the circumference, and both are aspherical.

[0148] The fourth lens L4 has negative refractive power and is made of plastic. Its object-side surface S7 is convex at the optical axis and concave at the circumference. Its image-side surface S8 is concave at the optical axis and at the circumference, and both are aspherical.

[0149] The fifth lens L5 has negative 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.

[0150] The sixth lens L6 has 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 convex at the optical axis and at the circumference, and both are aspherical.

[0151] The aperture STO may be located between the object side of the optical system and the sixth lens. In this embodiment, the aperture STO is disposed on a side of the first lens L1 away from the second lens L2 for controlling the amount of incoming light.

[0152] The infrared filter element IRCF is arranged after the sixth lens L6, and includes an object-side surface S13 and an image-side surface S14. 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 visible light is 380nm-780nm. The material of the infrared filter element IRCF is glass.

[0153] The imaging plane S15 is the plane where the image of the object is formed after the light passes through the optical system.

[0154] Table 5a shows the characteristics of the optical system of this embodiment, wherein the curvature radius in this embodiment is the curvature radius of each lens at the optical axis.

[0155] Table 5a

[0156]

[0157] Wherein, f is the effective focal length of the optical system, FNO is the aperture number of the optical system, FOV is the diagonal field of view of the optical system, and TTL is the distance from the object side of the first lens to the imaging plane of the optical system on the optical axis.

[0158] Table 5b gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of the aspheric mirror surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11 and S12 that can be used in the fifth embodiment.

[0159] Table 5b

[0160]

[0161]

[0162] Figure 11 The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the fifth embodiment are shown. Among them, the longitudinal spherical aberration curve represents the deviation of the focal point of light of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the meridional image curvature and sagittal image curvature; and the distortion curve represents the distortion value corresponding to different field angles. Figure 11 It can be seen that the optical system provided in the fifth embodiment can achieve good imaging quality.

[0163] Example 6

[0164] like Figure 12 As shown, line 11 represents the optical axis. The side of first lens L1 distal to second lens L2 is object side 12, and the side of sixth lens L6 distal to fifth lens L5 is image side 13. In the optical system provided in this embodiment, from object side 12 to image side 13, are aperture stop STO, first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, and infrared filter IRCF.

[0165] The first lens L1 has 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 convex at the optical axis and at the circumference, and both are aspherical.

[0166] The second lens L2 has negative 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 concave at the optical axis and at the circumference, and both are aspherical.

[0167] The third lens L3 has negative refractive power and is made of plastic. Its object-side surface S5 is convex at the optical axis and concave at the circumference. Its image-side surface S6 is concave at the optical axis and at the circumference, and both are aspherical.

[0168] The fourth lens L4 has negative refractive power and is made of plastic. Its object-side surface S7 is convex at the optical axis and concave at the circumference. Its image-side surface S8 is concave at the optical axis and at the circumference, and both are aspherical.

[0169] The fifth lens L5 has negative 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 concave at the optical axis and convex at the circumference. Both are aspherical.

[0170] The sixth lens L6 has 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 convex at the optical axis and at the circumference, and both are aspherical.

[0171] The aperture STO may be located between the object side of the optical system and the sixth lens. In this embodiment, the aperture STO is disposed on a side of the first lens L1 away from the second lens L2 for controlling the amount of incoming light.

[0172] The infrared filter element IRCF is arranged after the sixth lens L6, and includes an object-side surface S13 and an image-side surface S14. 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 visible light is 380nm-780nm. The material of the infrared filter element IRCF is glass.

[0173] The imaging plane S15 is the plane where the image of the object is formed after the light passes through the optical system.

[0174] Table 6a shows the characteristics of the optical system of this embodiment, wherein the curvature radius in this embodiment is the curvature radius of each lens at the optical axis.

[0175] Table 6a

[0176]

[0177]

[0178] Wherein, f is the effective focal length of the optical system, FNO is the aperture number of the optical system, FOV is the diagonal field of view of the optical system, and TTL is the distance from the object side of the first lens to the imaging plane of the optical system on the optical axis.

[0179] Table 6b gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of the aspheric mirror surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11 and S12 that can be used in the sixth embodiment.

[0180] Table 6b

[0181]

[0182]

[0183] Figure 13 The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the sixth embodiment are shown. Among them, the longitudinal spherical aberration curve represents the deviation of the focal point of light of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the meridional image curvature and sagittal image curvature; and the distortion curve represents the distortion value corresponding to different field angles. Figure 13 It can be seen that the optical system provided in the sixth embodiment can achieve good imaging quality.

[0184] Example 7

[0185] like Figure 14 As shown, line 11 represents the optical axis. The side of first lens L1 distal to second lens L2 is object side 12, and the side of sixth lens L6 distal to fifth lens L5 is image side 13. In the optical system provided in this embodiment, from object side 12 to image side 13, are aperture stop STO, first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, and infrared filter IRCF.

[0186] The first lens L1 has 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 convex at the circumference. Both are aspherical.

[0187] The second lens L2 has negative 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 concave at the optical axis and at the circumference, and both are aspherical.

[0188] The third lens L3 has negative refractive power and is made of plastic. Its object-side surface S5 is convex at the optical axis and concave at the circumference. Its image-side surface S6 is concave at the optical axis and at the circumference, and both are aspherical.

[0189] The fourth lens L4 has negative refractive power and is made of plastic. Its object-side surface S7 is convex at the optical axis and concave at the circumference. Its image-side surface S8 is concave at the optical axis and at the circumference, and both are aspherical.

[0190] The fifth lens L5 has 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.

[0191] The sixth lens L6 has negative refractive power and is made of plastic. Its object-side surface S11 is concave at the optical axis and at the circumference, and its image-side surface S12 is convex at the optical axis and at the circumference, and both are aspherical.

[0192] The aperture STO may be located between the object side of the optical system and the sixth lens. In this embodiment, the aperture STO is disposed on a side of the first lens L1 away from the second lens L2 for controlling the amount of incoming light.

[0193] The infrared filter element IRCF is arranged after the sixth lens L6, and includes an object-side surface S13 and an image-side surface S14. 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 visible light is 380nm-780nm. The material of the infrared filter element IRCF is glass.

[0194] The imaging plane S15 is the plane where the image of the object is formed after the light passes through the optical system.

[0195] Table 7a shows the characteristics of the optical system of this embodiment, wherein the curvature radius in this embodiment is the curvature radius of each lens at the optical axis.

[0196] Table 7a

[0197]

[0198] Wherein, f is the effective focal length of the optical system, FNO is the aperture number of the optical system, FOV is the diagonal field of view of the optical system, and TTL is the distance from the object side of the first lens to the imaging plane of the optical system on the optical axis.

[0199] Table 7b gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of the aspheric mirror surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11 and S12 that can be used in the seventh embodiment.

[0200] Table 7b

[0201]

[0202]

[0203] Figure 15 The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the seventh embodiment are shown. Among them, the longitudinal spherical aberration curve represents the deviation of the focal point of light of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the meridional image curvature and sagittal image curvature; and the distortion curve represents the distortion value corresponding to different field angles. Figure 15 It can be seen that the optical system provided in the seventh embodiment can achieve good imaging quality.

[0204] Example 8

[0205] like Figure 16 As shown, line 11 represents the optical axis. The side of first lens L1 distal to second lens L2 is object side 12, and the side of sixth lens L6 distal to fifth lens L5 is image side 13. In the optical system provided in this embodiment, from object side 12 to image side 13, are aperture stop STO, first lens L1, second lens L2, third lens L3, fourth lens L4, fifth lens L5, sixth lens L6, and infrared filter IRCF.

[0206] The first lens L1 has 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 convex at the optical axis and at the circumference, and both are aspherical.

[0207] The second lens L2 has negative refractive power and is made of plastic. Its object-side surface S3 is concave at the optical axis and convex at the circumference. Its image-side surface S4 is concave at the optical axis and at the circumference, and both are aspherical.

[0208] The third lens L3 has negative refractive power and is made of plastic. Its object-side surface S5 is convex at the optical axis and concave at the circumference. Its image-side surface S6 is concave at the optical axis and at the circumference, and both are aspherical.

[0209] The fourth lens L4 has negative refractive power and is made of plastic. Its object-side surface S7 is convex at the optical axis and concave at the circumference. Its image-side surface S8 is concave at the optical axis and at the circumference, and both are aspherical.

[0210] The fifth lens L5 has 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.

[0211] The sixth lens L6 has negative refractive power and is made of plastic. Its object-side surface S11 is concave at the optical axis and at the circumference, and its image-side surface S12 is convex at the optical axis and at the circumference, and both are aspherical.

[0212] The aperture STO may be located between the object side of the optical system and the sixth lens. In this embodiment, the aperture STO is disposed on a side of the first lens L1 away from the second lens L2 for controlling the amount of incoming light.

[0213] The infrared filter element IRCF is arranged after the sixth lens L6, and includes an object-side surface S13 and an image-side surface S14. 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 visible light is 380nm-780nm. The material of the infrared filter element IRCF is glass.

[0214] The imaging plane S15 is the plane where the image of the object is formed after the light passes through the optical system.

[0215] Table 8a shows the characteristics of the optical system of this embodiment, wherein the curvature radius in this embodiment is the curvature radius of each lens at the optical axis.

[0216] Table 8a

[0217]

[0218]

[0219] Wherein, f is the effective focal length of the optical system, FNO is the aperture number of the optical system, FOV is the diagonal field of view of the optical system, and TTL is the distance from the object side of the first lens to the imaging plane of the optical system on the optical axis.

[0220] Table 8b gives the higher-order coefficients A4, A6, A8, A10, A12, A14, A16, A18 and A20 of the aspheric mirror surfaces S1, S2, S3, S4, S5, S6, S7, S8, S9, S10, S11 and S12 that can be used in the eighth embodiment.

[0221] Table 8b

[0222]

[0223]

[0224] Figure 17 The longitudinal spherical aberration curve, astigmatism curve, and distortion curve of the optical system of the eighth embodiment are shown. Among them, the longitudinal spherical aberration curve represents the deviation of the focal point of light of different wavelengths after passing through each lens of the optical system; the astigmatism curve represents the meridional image curvature and sagittal image curvature; and the distortion curve represents the distortion value corresponding to different field angles. Figure 17 It can be seen that the optical system provided in the eighth embodiment can achieve good imaging quality.

[0225] Table 9 shows the values of ftLtl4 / ftGtl4, DL1 / Imgh, f / f1, f1 / f2, airL3 / TTL, (R5*R6) / (R5+R6), FBL / TTL, DL / Imgh, TTL / f, and TTL / DL of the optical systems of the first to eighth embodiments.

[0226] Table 9

[0227]

[0228] As can be seen from Table 9, each embodiment can meet the following requirements: 1 <ftLtl4 / ftGtl4<1.5,0.5<DL1 / Imgh<1,2<f / f1<3,-0.5<f1 / f2<-0.2,0.05<airL3 / TTL<0.3,1mm<(R5*R6) / (R5+R6)<4.5mm,FBL / TTL> 0.1, 0.5 <DL / Imgh<1,0.7<TTL / f<1,1.5<TTL / DL<2.2。

[0229] The above is a preferred embodiment of the present application. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present application. These improvements and modifications are also considered to be within the scope of protection of the present application.

Claims

1. An optical system, characterized in that: The device comprises a plurality of lenses, a total of six lenses with refractive power, and the plurality of lenses are arranged in sequence from the object side to the image side: A first lens having positive refractive power, wherein the object-side surface of the first lens is convex at the optical axis; A second lens element having negative refractive power, wherein the image-side surface of the second lens element is concave at the optical axis; a third lens having negative refractive power, wherein the object-side surface of the third lens is convex at the optical axis, and the image-side surface of the third lens is concave at the optical axis; a fourth lens element having negative refractive power, wherein the image-side surface of the fourth lens element is concave at the optical axis; The fifth lens has refractive power; a sixth lens having refractive power; The optical system satisfies the following conditional formula: 1 <ftLtl4 / ftGtl4<1.5, 1.5 <TTL / DL≤2.08, 2 <f / f1<3, Wherein, ftLtl4 is the longest distance from the object side surface of the fourth lens to the image side surface of the fourth lens in a direction parallel to the optical axis, ftGtl4 is the shortest distance from the object side surface of the fourth lens to the image side surface of the fourth lens in a direction parallel to the optical axis, TTL is the distance from the object side surface of the first lens to the imaging plane of the optical system on the optical axis, DL is the aperture of the aperture of the optical system, f is the effective focal length of the optical system, and f1 is the focal length of the first lens.

2. The optical system according to claim 1, wherein: The optical system satisfies the conditional formula: 0.7≤DL1 / Imgh<1, Wherein, DL1 is the effective aperture of the first lens, and Imgh is half of the diagonal length of the effective pixel area of the optical system on the imaging plane.

3. The optical system according to claim 1, wherein: The optical system satisfies the conditional formula: 2 <f / f1<2.47。 4. The optical system according to claim 1, wherein: The optical system satisfies the conditional formula: -0.5 <f1 / f2<-0.2, Wherein, f1 is the focal length of the first lens, and f2 is the focal length of the second lens.

5. The optical system according to claim 1, wherein: The optical system satisfies the conditional formula: 0.16≤airL3 / TTL<0.3, Wherein, airL3 is the distance on the optical axis from the image side surface of the third lens to the object side surface of the fourth lens, and TTL is the distance on the optical axis from the object side surface of the first lens to the imaging plane of the optical system.

6. The optical system according to claim 1, wherein: The optical system satisfies the conditional formula: 1mm<(R5*R6) / (R5+R6)<4.5mm, Wherein, R5 is the curvature radius of the object side surface of the third lens at the optical axis, and R6 is the curvature radius of the image side surface of the third lens at the optical axis.

7. The optical system according to claim 1, wherein: The optical system satisfies the conditional formula: 0.137≥FBL / TTL>0.1, Wherein, FBL is the distance from the intersection of the image-side surface of the sixth lens and the optical axis to the imaging plane on the optical axis, and TTL is the distance from the object-side surface of the first lens to the imaging plane of the optical system on the optical axis.

8. The optical system according to claim 1, wherein: The optical system further includes a stop located on the object side of the first lens or between two adjacent lenses. The optical system satisfies the following condition: 0.7≤DL / Imgh<1, Wherein, DL is the aperture of the diaphragm of the optical system, and Imgh is half of the diagonal length of the effective pixel area of the optical system on the imaging plane.

9. The optical system according to claim 1, wherein: The optical system satisfies the following condition: 1 <ftLtl4 / ftGtl4≤1.26。 10. The optical system according to claim 1, wherein: The optical system satisfies the conditional formula: 0.7 <TTL / f<1, Wherein, 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, and f is the effective focal length of the optical system.

11. A lens module, characterized in that: The optical system comprises a photosensitive element and the optical system according to any one of claims 1 to 10, wherein the photosensitive element is located on the image side of the optical system.

12. A terminal device, characterized in that: Comprising the lens module as claimed in claim 11.

Images