Optical lens

Abstract

The application provides an optical lens, which comprises seven lenses arranged along an optical axis from an object side to an imaging surface in sequence, wherein the seven lenses are: a first lens with negative optical power, the object side surface of which is a convex surface and the image side surface of which is a concave surface; a second lens with negative optical power, the object side surface of which is a convex surface and the image side surface of which is a concave surface; a third lens with positive optical power, the object side surface of which is a convex surface and the image side surface of which is a convex surface; a diaphragm; a fourth lens with positive optical power, the image side surface of which is a convex surface; a fifth lens with positive optical power, the object side surface of which is a convex surface; a sixth lens with negative optical power; and a seventh lens with optical power, the image side surface of which is a concave surface at a near optical axis; wherein the optical back focal length BFL of the optical lens and the effective focal length f of the optical lens satisfy 0.9 < BFL / f < 1.15. The application realizes the effects of large field of view, large aperture and miniaturization by reasonably matching the lens shapes and optical power combinations of the lenses.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of imaging lenses, in particular to an optical lens. BACKGROUND

[0002] With the development of mobile Internet, plus the popularity of social, video, live software, people's love for photography is getting higher and higher, and the pursuit of imaging effect is more diversified, which requires not only high image quality, but also a wide angle of view to record more information, which makes wide-angle high-definition imaging lenses receive more attention.

[0003] Because the wide-angle lens generally has a large distortion, the edge imaging effect is poor, and because the effective focal length of the wide-angle lens is short, the peripheral light entering will have a large compression deformation. Of course, the wide-angle lens has its unique angle of view and surrounding feeling, but it is seriously distorted for the flat change background. It is a difficult problem to overcome the distortion of the wide-angle lens. While correcting the distortion, more aberrations will be brought, so more pieces of lenses are often needed to correct the aberrations.

[0004] The development of chips also goes to two different directions, one is large target chip, which has good light flux, and is very suitable for high-quality image processing requirements. Under the same light conditions, it gets more light information, better image quality, and more information for post-processing. But at the same time, the disadvantage is that the product volume and weight are large. The second is the miniaturization of the chip, which has the advantage of reducing the volume and weight of the overall module, so that the finished product improves the portability. How to make the wide-angle lens match the advantages of the two, that is, to have the advantages of large target effect, high imaging quality and small distortion, and to reduce the weight of the module as much as possible and improve the portability, is a technical problem that needs to be solved by the technical personnel in the field. SUMMARY

[0005] In view of the above problems, the purpose of the present application is to provide an optical lens which can solve one or more of the above problems.

[0006] To achieve the above purpose, the present application provides an optical lens, which has seven lenses, arranged along the optical axis from the object side to the imaging surface in order: a first lens with negative focal power, whose object side is convex and image side is concave; a second lens with negative focal power, whose object side is convex and image side is concave; a third lens with positive focal power, whose object side is convex and image side is convex; a stop; a fourth lens with positive focal power, whose image side is convex; a fifth lens with positive focal power, whose object side is convex; a sixth lens with negative focal power; a seventh lens with focal power, whose image side is concave near the optical axis; wherein the optical back focal length BFL of the optical lens and the effective focal length f of the optical lens satisfy: 0.9 < BFL / f < 1.15.

[0007] Compared with the prior art, the optical lens provided by the present application has the advantages that the optical lens has a compact large-aperture structure, and more light flux can enter the optical lens, so that the optical lens can also form a clear image in a dim environment, and the effects of large field of view, large aperture and miniaturization are achieved. BRIEF DESCRIPTION OF DRAWINGS

[0008] Figure 1 FIG. 1 is a structural schematic diagram of an optical lens according to Embodiment 1 of the present application.

[0009] Figure 2 FIG. 2 is an optical distortion curve diagram of the optical lens according to Embodiment 1 of the present application.

[0010] Figure 3 FIG. 3 is an MTF curve diagram of the optical lens according to Embodiment 1 of the present application.

[0011] Figure 4 FIG. 4 is a curve diagram of the vertical axis chromatic aberration of the optical lens according to Embodiment 1 of the present application.

[0012] Figure 5 FIG. 5 is a structural schematic diagram of an optical lens according to Embodiment 2 of the present application.

[0013] Figure 6 FIG. 6 is an optical distortion curve diagram of the optical lens according to Embodiment 2 of the present application.

[0014] Figure 7 FIG. 7 is an MTF curve diagram of the optical lens according to Embodiment 2 of the present application.

[0015] Figure 8 FIG. 8 is a curve diagram of the vertical axis chromatic aberration of the optical lens according to Embodiment 2 of the present application.

[0016] Figure 9 FIG. 9 is a structural schematic diagram of an optical lens according to Embodiment 3 of the present application.

[0017] Figure 10 FIG. 10 is an optical distortion curve diagram of the optical lens according to Embodiment 3 of the present application.

[0018] Figure 11 FIG. 11 is an MTF curve diagram of the optical lens according to Embodiment 3 of the present application.

[0019] Figure 12 FIG. 12 is a curve diagram of the vertical axis chromatic aberration of the optical lens according to Embodiment 3 of the present application. DETAILED DESCRIPTION

[0020] For a better understanding of the present application, various aspects of the present application will be described in greater detail below with reference to the accompanying drawings. It is to be noted that these detailed descriptions are merely descriptive of embodiments of the present application and are not intended in any way to limit the scope of the present application. Throughout the specification, like drawing reference numerals refer to like elements. The expression "and / or" includes any and all combinations of one or more of the associated listed items.

[0021] It is to be noted that the expressions first, second, third and the like in this specification are used only to distinguish one feature from another feature, and do not denote any limitation of the features. Thus, the first lens discussed below can also be referred to as a second lens or a third lens without departing from the teachings of the present application.

[0022] In the drawings, the thickness, size, and shape of the lenses have been slightly exaggerated for the sake of explanation. Specifically, the shape of the spherical surface or aspherical surface shown in the drawings is shown by way of example. That is, the shape of the spherical surface or aspherical surface is not limited to the shape of the spherical surface or aspherical surface shown in the drawings. The drawings are merely examples and are not drawn to scale.

[0023] In this specification, the paraxial region refers to a region near the optical axis. If a lens surface is convex and the position of the convex surface is not specified, it means that the lens surface is convex at least in the paraxial region. If a lens surface is concave and the position of the concave surface is not specified, it means that the lens surface is concave at least in the paraxial region. The surface of each lens closest to the object is referred to as the object side surface of the lens, and the surface of each lens closest to the image plane is referred to as the image side surface of the lens.

[0024] It is also to be understood that the use of the terms "include", "includes", "including", "comprise", "comprises", "comprising", "have", "has", "having", or "contains" or "containing", when used in this specification, means that there are other items not listed which are also included in the statement, but do not, by themselves, limit the scope of the present application. Also, when describing embodiments of the present application, the use of "may" means one or more embodiments of the present application. Also, the use of the term "exemplary" is intended to present an example or an illustration.

[0025] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0026] It should be noted that the embodiments and the features in the embodiments of the present application can be combined with each other in the case of no conflict. The present application will be described in detail below with reference to the drawings and in combination with the embodiments.

[0027] The optical lens according to an embodiment of the present application comprises, in order from the object side to the image side: a first lens, a second lens, a third lens, a stop, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and a filter.

[0028] The first lens has negative refractive power, the object side surface of the first lens is a convex surface, and the image side surface of the first lens is a concave surface; the second lens has negative refractive power, the object side surface of the second lens is a convex surface, and the image side surface of the second lens is a concave surface; the third lens has positive refractive power, the object side surface of the third lens is a convex surface, and the image side surface of the third lens is a convex surface; the fourth lens has positive refractive power, the object side surface of the fourth lens is a convex surface or a concave surface, and the image side surface of the fourth lens is a convex surface; the fifth lens has positive refractive power, the object side surface of the fifth lens is a convex surface, and the image side surface of the fifth lens is a convex surface; the sixth lens has negative refractive power, the object side surface of the sixth lens is a concave surface, and the image side surface of the sixth lens is a convex surface or a concave surface; and the seventh lens has positive refractive power or negative refractive power, the object side surface of the seventh lens is a convex surface at the near optical axis, and the image side surface of the seventh lens is a concave surface at the near optical axis.

[0029] In some embodiments, the stop can be arranged between the third lens and the fourth lens, so as to converge the range of light rays exiting the front end of the optical lens and reduce the rear end aperture of the optical lens.

[0030] In some embodiments, the fifth lens and the sixth lens can be cemented to form a cemented lens, so as to share the chromatic aberration correction of the optical lens, improve the resolution of the optical lens, and make the structure of the optical lens compact, which is conducive to the miniaturization of the optical lens.

[0031] In some embodiments, the maximum half field angle θ of the optical lens satisfies 90°<θ<110°. Satisfying the above range is conducive to realizing the wide-angle characteristic, so that more scene information can be obtained, and the demand for large-range detection can be met.

[0032] In some embodiments, the incident angle CRA of the chief ray of the maximum field angle of the optical lens on the image plane satisfies 20°<CRA<40°. Satisfying the above range can make the CRA of the optical lens and the CRA of the photosensitive element of the chip have a larger allowable error range, and improve the adaptation ability of the optical lens to the image sensor.

[0033] In some embodiments, the optical back focal length BFL and the effective focal length f of the optical lens satisfy 0.9<BFL / f<1.15. Satisfying the above range can make the optical lens have a longer optical back focal length, which is conducive to the assembly of the optical lens.

[0034] In some embodiments, the optical total track length TTL of the optical lens and the effective focal length f satisfy: 10.2 < TTL / f < 12.0. Satisfying the above range, the length and volume of the optical lens can be effectively limited, and miniaturization of the optical lens can be achieved.

[0035] In some embodiments, the effective focal length f of the optical lens, the maximum half field angle θ, and the image height IH corresponding to the maximum half field angle satisfy: 50° < θxf / IH < 60°. Satisfying the above range, the requirements of wide-range detection and high-quality imaging can be balanced, and the adaptability of the optical lens can be improved.

[0036] In some embodiments, the combined focal length f12 of the first lens and the second lens and the effective focal length f of the optical lens satisfy: -2.0 < f12 / f < -1.2. Satisfying the above range, the power of the light combined by the first lens and the second lens can be appropriately balanced, the high-order aberration of the optical lens can be corrected, the back focal length of the optical lens can be shortened to maintain the miniaturization of the optical lens, and the divergence ability of the light beam by the front lens group can be controlled to facilitate the wide-angle of the optical lens.

[0037] In some embodiments, the radius of curvature R31 of the object side surface of the third lens and the center thickness CT3 of the third lens satisfy: 4.5 < R31 / CT3 < 6.0. Satisfying the above range, the deviation of the incidence angle and the exit angle of light rays of different fields of view can be reduced, the light rays can be smoothly transitioned, various aberrations such as the field curvature and the spherical aberration of the optical lens can be effectively corrected, and the off-axis sensitivity of the optical lens can be reduced.

[0038] In some embodiments, the air gap AT34 between the third lens and the fourth lens on the near optical axis and the optical total track length TTL of the optical lens satisfy: 0.06 < AT34 / TTL < 0.12. Satisfying the above range, by reasonably allocating the air gap between the third lens and the fourth lens and setting the stop position, the optical sensitivity can be effectively reduced while a reasonable chief ray incidence angle is obtained.

[0039] In some embodiments, the air gap AT12 between the first lens and the second lens on the near optical axis and the air gap AT23 between the second lens and the third lens on the near optical axis satisfy: 0.5 < AT12 / AT23 < 1.1; and the center thickness CT2 and the edge thickness ET2 of the second lens satisfy: 0.3 < CT2 / ET2 < 0.4. Satisfying the above range, the forming yield of the second lens and the assembly yield of the optical lens can be ensured, and the light rays can be converged to correct the aberration of the optical lens and improve the imaging quality of the optical lens.

[0040] In some embodiments, the fourth lens has a radius of curvature R41 on the object side and a radius of curvature R42 on the image side, and the following relationship is satisfied: 0.5 < (R41+R42) / (R41-R42) < 2.0; and the effective focal length f4 of the fourth lens and the effective focal length f of the optical lens satisfy: 1.0 < f4 / f < 4.0. Satisfying the above ranges can effectively control the power and surface shape of the fourth lens, correct high-order aberrations of the optical lens, and improve the imaging quality of the optical lens.

[0041] In some embodiments, the sum of the central thickness CT4 of the fourth lens, the central thickness CT5 of the fifth lens, the central thickness CT6 of the sixth lens, and the central thickness CT7 of the seventh lens and the effective focal length f of the optical lens satisfy: 2.7 < (CT4+CT5+CT6+CT7) / f < 3.2. Satisfying the above ranges can make the structure of the optical lens compact, facilitate miniaturization of the optical lens, and improve the illumination of the optical lens.

[0042] In some embodiments, the effective focal length f of the optical lens and the entrance pupil diameter EPD satisfy: 1.8 < f / EPD < 2.2. Satisfying the above ranges can facilitate large-aperture characteristics, and ensure clear images in low-light environments or at night.

[0043] In order to make the system have better optical performance, a plurality of aspherical lenses are used in the lens, and each aspherical surface shape of the optical lens satisfies the following equation:

[0044]

[0045] wherein z is the distance of the curved surface from the vertex of the curved surface in the direction of the optical axis, h is the distance from the optical axis to the curved surface, c is the curvature of the vertex of the curved surface, K is the quadratic surface coefficient, and A, B, C, D, E, F, and G are the second-order, fourth-order, sixth-order, eighth-order, tenth-order, twelfth-order, and fourteenth-order curved surface coefficients, respectively.

[0046] The application is further described in the following embodiments. In each embodiment, the thickness, the radius of curvature, and the material selection of each lens in the optical lens are different, and the specific differences can be referred to the parameter table of each embodiment. The following embodiments are merely preferred embodiments of the application, and the embodiments of the application are not limited to the following embodiments. Any changes, substitutions, combinations, or simplifications made without departing from the innovative points of the application should be regarded as equivalent replacement manners, and are included in the protection scope of the application.

[0047] Embodiment 1

[0048] Please refer to Figure 1Fig. 1 shows a structural schematic diagram of an optical lens provided in Embodiment 1 of the present application, which comprises, along an optical axis from an object side to an imaging surface S16, a first lens L1, a second lens L2, a third lens L3, a stop ST, a fourth lens L4, a fifth lens L5, a sixth lens L6, a seventh lens L7 and a filter G1.

[0049] The first lens L1 has a negative focal power, the object side S1 is a convex surface, and the image side S2 is a concave surface; the second lens L2 has a negative focal power, the object side S3 is a convex surface, and the image side S4 is a concave surface; the third lens L3 has a positive focal power, the object side S5 is a convex surface, and the image side S6 is a convex surface; the fourth lens L4 has a positive focal power, the object side S7 is a concave surface, and the image side S8 is a convex surface; the fifth lens L5 has a positive focal power, the object side S9 is a convex surface, and the image side is a convex surface; the sixth lens L6 has a negative focal power, the object side is a concave surface, and the image side S11 is a convex surface; the fifth lens L5 and the sixth lens L6 are cemented to form a cemented lens, and the cemented surface is S10; the seventh lens L7 has a negative focal power, the object side S12 is a convex surface near the optical axis, and the image side S13 is a concave surface near the optical axis; the filter G1 has a flat object side S14 and a flat image side S15.

[0050] The related parameters of the lenses in the optical lens in Embodiment 1 are shown in Table 1-1.

[0051] Table 1-1

[0052]

[0053] The curve coefficients of the aspherical lenses of the optical lens in Embodiment 1 are shown in Table 1-2.

[0054] Table 1-2

[0055]

[0056]

[0057] Figure 2 The optical distortion curve of Embodiment 1 is shown, which represents the distortion at different fields of view on the imaging surface, the horizontal axis represents percentage, and the vertical axis represents half field of view (unit: °). As can be seen from the figure, the optical distortion of the present embodiment is controlled within 12%, which indicates that the distortion of the optical lens is well corrected.

[0058] Figure 3A modulation transfer function (MTF) curve of the optical lens of Embodiment 1 is shown, which represents the imaging modulation degree of different spatial frequencies under each field of view, the horizontal axis represents spatial frequency (unit: lp / mm), and the vertical axis represents MTF value. As can be seen from the figure, the MTF value of the present embodiment is above 0.4 in the full field of view, and in the range of 0-150 lp / mm, the MTF curve uniformly and smoothly decreases from the center to the edge of the field of view, and has good imaging quality and good detail resolution capability in the case of low frequency and high frequency.

[0059] Figure 4 A curve of the axial chromatic aberration of Embodiment 1 is shown, which represents the chromatic aberration of different image heights on the imaging surface at each wavelength relative to the center wavelength (0.55 μm), the horizontal axis represents the axial chromatic aberration value of each wavelength relative to the center wavelength (unit: μm), and the vertical axis represents the normalized field angle. As can be seen from the figure, the axial chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±1 μm, which indicates that the optical lens can very well correct the chromatic aberration of the edge field of view and the secondary spectrum of the entire image surface.

[0060] Embodiment 2

[0061] Please refer to Figure 5 , which is a structural schematic diagram of the optical lens provided in Embodiment 2 of the present application. The optical lens in the present embodiment has substantially the same structure and shape as the optical lens in Embodiment 1, and the main difference is that the seventh lens has positive focal power, and the curvature radius, center thickness, edge thickness and material of each lens are changed.

[0062] The related parameters of each lens in the optical lens in Embodiment 2 are shown in Table 2-1.

[0063] Table 2-1

[0064]

[0065]

[0066] The curve coefficients of the aspherical lenses of the optical lens in Embodiment 2 are shown in Table 2-2.

[0067] Table 2-2

[0068] Face No. K A B C S3 -1.55E+00 0.00E+00 -2.35E-02 2.28E-03 S4 -9.80E-01 0.00E+00 -1.80E-02 3.08E-03 S7 -2.00E+02 0.00E+00 -2.62E-02 -3.79E-02 S8 2.68E+00 0.00E+00 -7.85E-03 1.97E-03 S12 -1.37E+01 0.00E+00 -2.15E-03 -3.41E-03 S13 -4.87E+01 0.00E+00 3.31E-03 -2.21E-03 Face No. D E F G S3 -2.35E-04 2.03E-05 -7.92E-07 0.00E+00 S4 -2.26E-03 5.28E-04 -3.99E-05 0.00E+00 S7 4.44E-02 -4.54E-02 1.27E-02 0.00E+00 S8 3.67E-04 -2.31E-03 1.06E-03 0.00E+00 S12 -2.23E-03 6.64E-04 -7.56E-05 0.00E+00 S13 -1.49E-03 1.55E-04 -3.70E-06 0.00E+00

[0069] Figure 6 to Figure 8The distortion curve, the modulation transfer function (MTF) curve and the axial chromatic aberration curve of the optical lens of embodiment 2 are shown in the figures respectively. As can be seen from the figures, the optical distortion is controlled within 9%, which indicates that the distortion of the optical lens is well corrected; the MTF value of the optical lens is all above 0.5 within the full field of view, and within the range of 0-150 lp / mm, the MTF curve uniformly and smoothly decreases from the center to the edge of the field of view, and the optical lens has good imaging quality and good detail resolution ability in the case of low frequency and high frequency; the axial chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±1 μm, which indicates that the optical lens can well correct the chromatic aberration of the edge of the field of view and the secondary spectrum of the whole image plane.

[0070] Embodiment 3

[0071] Please refer to Figure 9 , which is a structural schematic diagram of the optical lens provided in embodiment 3 of the present application. The optical lens in the embodiment is substantially the same as the optical lens in embodiment 1 in structure and shape, and the difference mainly lies in that the curvature radius, the center thickness, the edge thickness and the material of each lens are changed.

[0072] The related parameters of each lens in the optical lens in embodiment 3 are shown in Table 3-1.

[0073] Table 3-1

[0074]

[0075] The curve coefficients of the aspherical lens of the optical lens in embodiment 3 are shown in Table 3-2.

[0076] Table 3-2

[0077] Face No. K A B C S3 -1.81E+00 0.00E+00 -9.01E-03 -7.02E-04 S4 -8.90E-01 0.00E+00 -4.18E-02 2.76E-03 S7 -1.20E+02 0.00E+00 -5.47E-02 -4.73E-02 S8 2.20E+00 0.00E+00 -2.29E-02 3.24E-03 S12 2.92E+00 0.00E+00 -5.09E-02 8.85E-04 S13 2.79E+00 0.00E+00 -3.60E-02 -1.55E-03 Face No. D E F G S3 1.55E-04 -1.14E-05 4.77E-07 -1.13E-08 S4 -2.43E-03 5.08E-04 -4.69E-05 7.79E-07 S7 5.16E-02 -8.54E-02 -4.92E-03 2.50E-02 S8 -2.07E-03 -1.21E-03 2.16E-04 -2.69E-05 S12 -7.80E-04 3.46E-04 -1.38E-06 1.10E-06 S13 9.76E-04 -3.58E-04 7.02E-05 -6.99E-06

[0078] Figure 10 to Figure 12 The distortion curve, the modulation transfer function (MTF) curve and the axial chromatic aberration curve of the optical lens of embodiment 3 are shown in the figures respectively. As can be seen from the figures, the optical distortion is controlled within 12%, which indicates that the distortion of the optical lens is well corrected; the MTF value of the optical lens is all above 0.35 within the full field of view, and within the range of 0-150 lp / mm, the MTF curve uniformly and smoothly decreases from the center to the edge of the field of view, and the optical lens has good imaging quality and good detail resolution ability in the case of low frequency and high frequency; the axial chromatic aberration of the longest wavelength and the shortest wavelength is controlled within ±1 μm, which indicates that the optical lens can well correct the chromatic aberration of the edge of the field of view and the secondary spectrum of the whole image plane.

[0079] Please refer to Table 4 for the optical characteristics of the above-mentioned embodiments, including the effective focal length f, the maximum half field angle θ, the entrance pupil diameter EPD, the total track length TTL, the F-number FNO, the true image height IH, and the numerical values corresponding to each conditional expression in the embodiments of the optical lens.

[0080] Table 4

[0081] Parameter and Condition Formula Example 1 Example 2 Example 3 f (mm) 1.253 1.120 1.255 θ (°) 100 100 100 EPD (mm) 0.627 0.561 0.628 TTL (mm) 13.118 13.022 13.502 FNO 2.00 2.00 2.04 IH (mm) 2.310 2.014 2.317 CRA (°) 30.0 30.4 30.5 BFL / f 0.929 1.065 0.948 TTL / f 10.495 11.606 10.757 θ x f / IH (°) 54.242 55.611 54.165 f12 / f -1.566 -1.333 -1.646 R31 / CT3 5.489 4.930 5.087 AT34 / TTL 0.077 0.110 0.080 AT12 / AT23 0.696 1.014 0.676 CT2 / ET2 0.354 0.339 0.334 f4 / f 2.520 3.244 2.535 (R41+R42) / (R41-R42) 1.018 0.982 1.004 (CT4+CT5+CT6+CT7) / f 2.859 3.079 2.900 f / EPD 2.0 2.0 2.0

[0082] In summary, the optical lens of the embodiments of the present application realizes the effects of large field of view, large aperture, and miniaturization by reasonably matching the lens shape and power combination between each lens.

[0083] In the description of the present specification, the description referring to the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0084] The above-mentioned embodiments only express several implementation manners of the present application, and the description is relatively specific and detailed, but it should not be understood as a limitation on the scope of the patent of the present application. It should be noted that, for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. An optical lens, in total seven pieces of lenses, characterized in that, In order from the object side to the imaging surface along the optical axis, there are: a first lens with negative refractive power, an object side surface of the first lens being convex, an image side surface of the first lens being concave; a second lens with negative refractive power, an object side surface of the second lens being convex, an image side surface of the second lens being concave; a third lens with positive refractive power, an object side surface of the third lens being convex, an image side surface of the third lens being convex; a diaphragm; a fourth lens with positive refractive power, an image side surface of the fourth lens being convex; a fifth lens with positive refractive power, an object side surface of the fifth lens being convex; a sixth lens with negative refractive power; a seventh lens with refractive power, an image side surface of the seventh lens being concave at the near optical axis; wherein an optical back focal length BFL of the optical lens and an effective focal length f of the optical lens satisfy: 0.9 < BFL / f < 1.15; a maximum half field angle θ of the optical lens, the effective focal length f of the optical lens, and an image height IH corresponding to the maximum half field angle θ of the optical lens satisfy: 50° < θ×f / IH < 60°; a combined focal length f12 of the first lens and the second lens and the effective focal length f of the optical lens satisfy: -1.566 ≤ f12 / f < -1.2; a curvature radius R31 of the object side surface of the third lens and a central thickness CT3 of the third lens satisfy: 4.5 < R31 / CT3 < 6.

0.

2. The optical lens of claim 1, wherein, an optical total length TTL of the optical lens and the effective focal length f of the optical lens satisfy: 10.2 < TTL / f < 12.

0.

3. The optical lens of claim 1, wherein, an effective focal length f4 of the fourth lens and the effective focal length f of the optical lens satisfy: 1.0 < f4 / f < 4.

0.

4. The optical lens of claim 1, wherein, an optical back focal length BFL of the optical lens and an effective focal length f of the optical lens satisfy: 0.929 ≤ BFL / f ≤ 1.065; a maximum half field angle θ of the optical lens, the effective focal length f of the optical lens, and an image height IH corresponding to the maximum half field angle θ of the optical lens satisfy: 54.165° ≤ θ×f / IH ≤ 55.611°.

5. The optical lens of claim 1, wherein, a combined focal length f12 of the first lens and the second lens and the effective focal length f of the optical lens satisfy: -1.566 ≤ f12 / f ≤ -1.333; a curvature radius R31 of the object side surface of the third lens and a central thickness CT3 of the third lens satisfy: 4.930 ≤ R31 / CT3 ≤ 5.

489.

6. The optical lens of claim 1, wherein, an air separation AT34 between the third lens and the fourth lens on the near optical axis and an optical total length TTL of the optical lens satisfy: 0.06 < AT34 / TTL < 0.

12.

7. The optical lens of claim 1, wherein, an air separation AT12 between the first lens and the second lens on the near optical axis and an air separation AT23 between the second lens and the third lens on the near optical axis satisfy: 0.5 < AT12 / AT23 < 1.

1.

8. The optical lens of claim 1, wherein, a curvature radius R41 of the object side surface of the fourth lens and a curvature radius R42 of the image side surface of the fourth lens satisfy: 0.5 < (R41+R42) / (R41-R42) < 2.

0.

9. The optical lens of claim 1, wherein, A sum of a center thickness CT4 of the fourth lens, a center thickness CT5 of the fifth lens, a center thickness CT6 of the sixth lens, and a center thickness CT7 of the seventh lens and an effective focal length f of the optical lens satisfy: 2.7 < (CT4+CT5+CT6+CT7) / f < 3.

2.

10. The optical lens of claim 1, wherein, The effective focal length f of the optical lens and an entrance pupil diameter EPD of the optical lens satisfy: 1.8 < f / EPD < 2.2.

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