A wide-angle lens

Abstract

The present invention discloses a wide-angle lens, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens arranged in sequence along the optical axis from the object plane to the image plane; the first lens and the sixth lens are both negative power lenses, the third lens, the fourth lens, the fifth lens and the seventh lens are all positive power lenses, the second lens is a negative power lens or a positive power lens; the focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3, and the focal length of the sixth lens is f4. The focal length of the wide-angle lens is f3, the focal length of the fourth lens is f4, the focal length of the fifth lens is f5, the focal length of the sixth lens is f6, the focal length of the seventh lens is f7, and the focal length of the wide-angle lens is f, where: 0.3≤|f1 / f|≤2.6;|f2 / f|≥2; 2.3≤|f3 / f|≤7.2;|f4 / f|≥0.8; 0.67≤|f5 / f|≤2.94; 0.32≤|f6 / f|≤2.77; and |f7 / f|≥0.16. The wide-angle lens provided by the present invention ensures that the requirements for high-definition and low-distortion surveillance are met at a low cost.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of optical devices, and in particular to a wide-angle lens. Background Art

[0002] The rapidly developing security industry is undergoing rapid development, especially in the field of video surveillance, which has experienced rapid growth in recent years. Currently, 1080P can no longer fully meet market needs, with 4K becoming the future trend. The rapid rise of the live streaming industry in recent years has placed increasingly stringent demands on higher-definition and more intelligent lenses. However, currently available lenses struggle to balance clarity, distortion, and cost. Higher-definition lenses often exhibit significant distortion, resulting in unrealistic images and prohibitively high costs. Therefore, a low-cost, high-definition lens with minimal distortion is needed to address these issues. Summary of the Invention

[0003] The present invention provides a wide-angle lens, which can meet the monitoring requirements of high definition and small distortion at a low cost.

[0004] An embodiment of the present invention provides a wide-angle lens, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, which are arranged in sequence along an optical axis from an object plane to an image plane;

[0005] The first lens and the sixth lens are both negative power lenses, the third lens, the fourth lens, the fifth lens and the seventh lens are all positive power lenses, and the second lens is a negative power lens or a positive power lens;

[0006] The focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3, the focal length of the fourth lens is f4, the focal length of the fifth lens is f5, the focal length of the sixth lens is f6, the focal length of the seventh lens is f7, and the focal length of the wide-angle lens is f, wherein:

[0007] 0.3≤|f1 / f|≤2.6; |f2 / f|≥2; 2.3≤|f3 / f|≤7.2; |f4 / f|≥0.8; 0.67≤|f5 / f|≤2.94; 0.32≤|f6 / f|≤2.77; |f7 / f|≥0.16.

[0008] Optionally, the second lens is a negative power lens; the third lens is a glass spherical lens; the first lens, the second lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are all plastic aspherical lenses; the wide-angle lens further includes a first aperture stop, which is disposed in the optical path between the fourth lens and the fifth lens;

[0009] Alternatively, the second lens is a positive power lens; the fifth lens is a glass aspheric lens, and the first lens, the second lens, the third lens, the fourth lens, the sixth lens and the seventh lens are all plastic aspheric lenses; the wide-angle lens further includes a second aperture, which is arranged in the optical path between the third lens and the fourth lens.

[0010] Optionally, the refractive index of the first lens is n1; the refractive index of the second lens is n2, and the Abbe number is v2; the refractive index of the third lens is n3, and the Abbe number is v3; the refractive index of the fourth lens is n4, and the Abbe number is v4; the refractive index of the seventh lens is n7; wherein:

[0011] 1.43≤n1≤1.9; 1.50≤n2≤1.75, 19≤v2≤56; n3≥1.43, v3≥18.6; 1.53≤n4≤1.68, v4≥19; 1.53≤n7≤1.67.

[0012] Optionally, the sag of the object-side surface of the first lens is SAG11, and the sag of the image-side surface of the first lens is SAG12, wherein 0.08≤|SAG11 / SAG12|≤1.5.

[0013] Optionally, a radius of curvature of the object side surface of the second lens is R21, where |R21|≥1.42.

[0014] Optionally, the center thickness of the fourth lens is CT4, and the center thickness of the fifth lens is CT5, wherein |CT4 / CT5|≤1.88.

[0015] Optionally, a radius of curvature of the object-side surface of the fifth lens is R51, and a radius of curvature of the image-side surface of the fifth lens is R52, wherein |R51 / R52|≥2.23.

[0016] Optionally, the fourth lens is a meniscus lens.

[0017] Optionally, the distance from the optical axis center of the image-side surface of the seventh lens to the image plane is BFL, and the distance from the optical axis center of the object-side surface of the first lens to the image plane is TTL, where 0.11≤BFL / TTL≤0.89.

[0018] Optionally, the aperture of the wide-angle lens is F, where 0.6≤f / F≤2.8.

[0019] The wide-angle lens provided by the embodiment of the present invention ensures the balance of the incident angles of the front and rear lens groups of the wide-angle lens at a low cost by rationally setting the number of lenses in the wide-angle lens, the optical power of each lens, and the relative relationship between the focal lengths of each lens, reduces the sensitivity of the lens, and corrects aberrations at ultra-large apertures, thereby ensuring that the wide-angle lens has high resolution and meets the requirements of high-definition and low-distortion surveillance. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 A schematic structural diagram of a wide-angle lens provided by an embodiment of the present invention;

[0021] Figure 2 A schematic structural diagram of another wide-angle lens provided by an embodiment of the present invention;

[0022] Figure 3 A spherical aberration curve diagram of a wide-angle lens provided in Example 1 of the present invention;

[0023] Figure 4 A ray fan diagram of a wide-angle lens provided in Example 1 of the present invention;

[0024] Figure 5 A point diagram of a wide-angle lens provided in Example 1 of the present invention;

[0025] Figure 6 The vertical axis chromatic aberration of a wide-angle lens provided in the first embodiment of the present invention;

[0026] Figure 7 A field curvature distortion diagram of a wide-angle lens provided in Example 1 of the present invention;

[0027] Figure 8 This is an MTF diagram of a wide-angle lens provided in Example 1 of the present invention;

[0028] Figure 9 A spherical aberration curve diagram of a wide-angle lens provided in Example 2 of the present invention;

[0029] Figure 10 A ray fan diagram of a wide-angle lens provided in the second embodiment of the present invention;

[0030] Figure 11 A spot diagram of a wide-angle lens provided in Example 2 of the present invention;

[0031] Figure 12 The vertical axis chromatic aberration of a wide-angle lens provided in the second embodiment of the present invention;

[0032] Figure 13 A field curvature distortion diagram of a wide-angle lens provided in Example 2 of the present invention;

[0033] Figure 14 This is an MTF diagram of a wide-angle lens provided in Example 2 of the present invention. DETAILED DESCRIPTION

[0034] The present invention will be further described in detail below with reference to the accompanying drawings and examples. It will be understood that the specific embodiments described herein are intended only to illustrate the present invention and are not intended to limit the present invention. It should also be noted that, for ease of description, the accompanying drawings only illustrate portions relevant to the present invention, not all structures.

[0035] Figure 1 A schematic structural diagram of a wide-angle lens provided by an embodiment of the present invention is shown in FIG. Figure 1 As shown, the wide-angle lens provided by the embodiment of the present invention includes a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, a fifth lens 150, a sixth lens 160 and a seventh lens 170, which are arranged in sequence along the optical axis from the object plane to the image plane. The first lens 110 and the sixth lens 160 are both negative optical power lenses, the third lens 130, the fourth lens 140, the fifth lens 150 and the seventh lens 170 are all positive optical power lenses, and the second lens 120 is a negative optical power lens or a positive optical power lens. The focal length of the first lens 110 is f1, the focal length of the second lens 120 is f2, the focal length of the third lens 130 is f3, the focal length of the fourth lens 140 is f4, the focal length of the fifth lens 150 is f5, the focal length of the sixth lens 160 is f6, and the focal length of the seventh lens 170 is f7. The focal length of the wide-angle lens is f, where: 0.3≤|f1 / f|≤2.6; |f2 / f|≥2; 2.3≤|f3 / f|≤7.2; |f4 / f|≥0.8; 0.67≤|f5 / f|≤2.94; 0.32≤|f6 / f|≤2.77; and |f7 / f|≥0.16.

[0036] Exemplarily, the optical power is equal to the difference between the convergence of the image-side light beam and the convergence of the object-side light beam, and it characterizes the ability of the optical system to deflect light. The larger the absolute value of the optical power, the stronger the ability to bend light, and the smaller the absolute value of the optical power, the weaker the ability to bend light. When the optical power is a positive number, the refraction of light is convergent; when the optical power is a negative number, the refraction of light is divergent. The optical power can be applied to characterize a certain refractive surface of a lens (i.e., a surface of a lens), can be applied to characterize a certain lens, and can also be applied to characterize a system formed by multiple lenses (i.e., a lens group). In the wide-angle lens provided in an embodiment of the present invention, each lens can be fixed to a lens barrel ( Figure 1Within the optical system (not shown), a first lens 110 is configured as a negative power lens for controlling the incident angle of light in the optical system; a second lens 120 is configured as a negative or positive power lens; a third lens 130 and a fourth lens 140 are both positive power lenses, and are configured to focus the forward light beam; a fifth lens 150 is configured as a positive power lens; a sixth lens 160 is configured as a negative power lens; and a seventh lens 170 is configured as a positive power lens. The fifth, sixth, and seventh lenses 150, 160, 170 are configured to correct off-axis aberrations, including field curvature, coma, and astigmatism. The entire lens system ensures approximately proportional distribution of optical power within the optical system and balances the incident angles of the front and rear lens groups, thereby reducing lens sensitivity and improving production feasibility.

[0037] Furthermore, the focal length f1 of the first lens element 110, the focal length f2 of the second lens element 120, the focal length f3 of the third lens element 130, the focal length f4 of the fourth lens element 140, the focal length f5 of the fifth lens element 150, the focal length f6 of the sixth lens element 160, the focal length f7 of the seventh lens element 170, and the focal length f of the wide-angle lens are set to meet the following conditions: 0.3 ≤ |f1 / f| ≤ 2.6; |f2 / f| ≥ 2; 2.3 ≤ |f3 / f| ≤ 7.2; |f4 / f| ≥ 0.8; 0.67 ≤ |f5 / f| ≤ 2.94; 0.32 ≤ |f6 / f| ≤ 2.77; and |f7 / f| ≥ 0.16. By rationally allocating the focal lengths of the lenses, aberration correction is facilitated at ultra-large apertures, ensuring that the lens has high resolution.

[0038] The wide-angle lens provided by the embodiment of the present invention ensures the balance of the incident angles of the front and rear lens groups of the wide-angle lens at a low cost by rationally setting the number of lenses in the wide-angle lens, the optical power of each lens, and the relative relationship between the focal lengths of each lens, reduces the sensitivity of the lens, and corrects aberrations at ultra-large apertures, thereby ensuring that the wide-angle lens has high resolution and meets the requirements of high-definition and low-distortion surveillance.

[0039] Continue to refer Figure 1 Optionally, the second lens 120 is a negative power lens, the third lens 130 is a glass spherical lens, the first lens 110, the second lens 120, the fourth lens 140, the fifth lens 150, the sixth lens 160 and the seventh lens 170 are all plastic aspherical lenses; the wide-angle lens also includes a first aperture 180, which is arranged in the optical path between the fourth lens 140 and the fifth lens 150.

[0040] Among them, the second lens 120 adopts a negative optical focal length lens for correcting off-axis aberrations. The third lens 130 is a glass spherical lens, and the first lens 110, the second lens 120, the fourth lens 140, the fifth lens 150, the sixth lens 160 and the seventh lens 170 are all plastic aspherical lenses. The aspherical lenses play a role in correcting all high-order aberrations. Since the cost of lenses made of plastic material is much lower than that of lenses made of glass material, the wide-angle lens provided by the embodiment of the present invention has good image quality and low cost by setting 6 plastic aspherical lenses. And because the two types of materials have a mutual compensation effect, the wide-angle lens can be guaranteed to be able to be used normally in high and low temperature environments. By setting the first aperture 180 in the optical path between the fourth lens 140 and the fifth lens 150, the propagation direction of the light beam can be adjusted, and the incident angle of the light can be adjusted, which is beneficial to improving the imaging quality.

[0041] In other embodiments, the second lens 120 may also be a positive power lens. Figure 2 A schematic structural diagram of another wide-angle lens provided by an embodiment of the present invention is shown in FIG. Figure 2 As shown, the fifth lens 150 is a glass aspheric lens, and the first lens 110, the second lens 120, the third lens 130, the fourth lens 140, the sixth lens 160 and the seventh lens 170 are all plastic aspheric lenses; the wide-angle lens further includes a second aperture 190, which is arranged in the optical path between the third lens 130 and the fourth lens 140.

[0042] Among them, the fifth lens 150 is a glass aspheric lens, and the first lens 110, the second lens 120, the third lens 130, the fourth lens 140, the sixth lens 160 and the seventh lens 170 are all plastic aspheric lenses. The aspheric lenses play a role in correcting all high-order aberrations. Since the cost of lenses made of plastic material is much lower than that of lenses made of glass material, the wide-angle lens provided by the embodiment of the present invention has good image quality and low cost by setting 6 plastic aspheric lenses. And because the two types of materials have a mutual compensation effect, the wide-angle lens can be guaranteed to be able to still be used normally in high and low temperature environments. By setting the second aperture 190 in the optical path between the third lens 130 and the fourth lens 140, the propagation direction of the light beam can be adjusted, and the incident angle of the light can be adjusted, which is conducive to improving the imaging quality.

[0043] It should be noted that the material of the above-mentioned plastic aspheric lens can be various plastics known to those skilled in the art, and the material of the glass spherical lens can be various types of glass known to those skilled in the art, which will not be elaborated or limited in the embodiments of the present invention.

[0044] Optionally, the refractive index of the first lens 110 is n1; the refractive index of the second lens 120 is n2, and the Abbe number is v2; the refractive index of the third lens 130 is n3, and the Abbe number is v3; the refractive index of the fourth lens 140 is n4, and the Abbe number is v4; the refractive index of the seventh lens 170 is n7; wherein: 1.43≤n1≤1.9; 1.50≤n2≤1.75, 19≤v2≤56; n3≥1.43, v3≥18.6; 1.53≤n4≤1.68, v4≥19; 1.53≤n7≤1.67.

[0045] The refractive index is the ratio of the speed of light in a vacuum to the speed of light in the medium. It primarily describes a material's ability to refract light, and different materials have different refractive indices. The Abbe number is an index used to indicate the dispersion capacity of a transparent medium. The greater the dispersion, the smaller the Abbe number; conversely, the less dispersion, the larger the Abbe number. By matching the refractive index and Abbe number of each lens in a wide-angle lens, we ensure a balanced angle of incidence between the front and rear elements, reducing lens sensitivity and facilitating higher pixel resolution.

[0046] Optionally, the sag of the object-side surface of the first lens 110 is SAG11, and the sag of the image-side surface of the first lens 110 is SAG12, where 0.08≤|SAG11 / SAG12|≤1.5.

[0047] The sag represents the vertical distance from the highest point to the lowest point on the lens surface. By setting the sag SAG11 on the object side and the sag SAG12 on the image side of the first lens 110 to satisfy 0.08≤|SAG11 / SAG12|≤1.5, it helps to reasonably control the incident angle of light in the optical system.

[0048] Optionally, the object-side surface of the second lens 120 has a curvature radius of R21, where |R21|≥1.42.

[0049] The unit of the curvature radius is millimeter (mm). By setting the curvature radius R21 of the object side surface of the second lens 120 to satisfy |R21|≥1.42, it is helpful to shorten the total length of the optical path and ensure that the overall volume of the lens is small.

[0050] Optionally, the center thickness of the fourth lens 140 is CT4, and the center thickness of the fifth lens 150 is CT5, wherein |CT4 / CT5|≤1.88.

[0051] The central thickness CT4 of the fourth lens element 140 and the central thickness CT5 of the fifth lens element 150 are set to satisfy |CT4 / CT5|≤1.88, thereby properly controlling the aperture of the wide-angle lens and facilitating correction of aberrations.

[0052] Optionally, the object-side surface of the fifth lens 150 has a curvature radius of R51, and the image-side surface of the fifth lens 150 has a curvature radius of R52, where |R51 / R52|≥2.23.

[0053] The object-side surface of the fifth lens 150 has a curvature radius R51 and an image-side surface of the fifth lens 150 such that |R51 / R52|≥2.23, thereby making the object-side surface of the fifth lens 150 flatter and improving imaging quality.

[0054] Optionally, the fourth lens 140 is a meniscus lens.

[0055] Among them, the meniscus lens is composed of two spherical surfaces with small curvature radii and little numerical difference. Setting the fourth lens as a meniscus lens helps to correct field curvature.

[0056] Optionally, the distance from the optical axis center of the image-side surface of the seventh lens 170 to the image plane is BFL, and the distance from the optical axis center of the object-side surface of the first lens 110 to the image plane is TTL, where 0.11≤BFL / TTL≤0.89.

[0057] Among them, the distance from the optical axis center of the image-side surface of the seventh lens 170 to the image plane can be understood as the back focus of the wide-angle lens, and the distance from the optical axis center of the object-side surface of the first lens 110 to the image plane can be understood as the total optical length of the wide-angle lens. By reasonably setting the relationship between the back focus of the wide-angle lens and the total optical length of the wide-angle lens, the entire wide-angle lens can be ensured to have a compact structure and a high degree of integration.

[0058] As a feasible implementation, the aperture number F and the focal length f of the wide-angle lens provided in the embodiment of the present invention satisfy 0.6≤f / F≤2.8, meeting the monitoring requirements of high definition and low distortion at ultra-large aperture.

[0059] The wide-angle lens provided by the embodiments of the present invention ensures the balance of the incident angles of the front and rear lens groups of the wide-angle lens at a low cost by rationally allocating the optical power, surface shape, Abbe number, and center thickness of each lens. This reduces the sensitivity of the lens and corrects aberrations at ultra-large apertures, ensuring that the wide-angle lens has high resolution and meets the requirements of high-definition surveillance with minimal distortion.

[0060] Specific embodiments of the optical imaging lens assembly applicable to the above-mentioned embodiments will be further described below with reference to the accompanying drawings.

[0061] Example 1

[0062] Continue to refer Figure 1The wide-angle lens provided in Example 1 of the present invention includes a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, a fifth lens 150, a sixth lens 160, and a seventh lens 170, arranged in sequence along the optical axis from the object plane to the image plane. A first aperture 180 is provided in the optical path between the fourth lens 140 and the fifth lens 150. Table 1 shows the optical physical parameters of each lens in the wide-angle lens provided in Example 1, such as the surface type, curvature radius, thickness, and material.

[0063] Table 1 Optical and physical parameters of wide-angle lens

[0064]

[0065]

[0066] The surface numbers are numbered according to the order of the lens surfaces. For example, surface numbers 1 and 2 are the object-side and image-side surfaces of the first lens 110, respectively; surface numbers 3 and 4 are the object-side and image-side surfaces of the second lens 120, respectively; and so on. The radius of curvature represents the degree of curvature of the lens surface; a positive value indicates that the surface is curved toward the image plane, while a negative value indicates that the surface is curved toward the object plane. The thickness represents the axial distance from the center of the current surface to the next surface, and the units of both the radius of curvature and thickness are millimeters (mm).

[0067] Based on the above implementation, optionally, the third lens 130 is a glass spherical lens, and the first lens 110, the second lens 120, the fourth lens 140, the fifth lens 150, the sixth lens 160, and the seventh lens 170 are all plastic aspherical lenses. The wide-angle lens provided in this embodiment of the present invention also includes a first aperture 180 (STO). The addition of this first aperture 180 can adjust the propagation direction of the light beam, thereby improving imaging quality. The first aperture 180 can be located in the optical path between the fourth lens 140 and the fifth lens 150, but this embodiment of the present invention does not limit the specific location of the first aperture 180.

[0068] The aspheric surface shape equation Z of the first lens 110, the second lens 120, the third lens 130, the fourth lens 140, the fifth lens 150, the sixth lens 160, and the seventh lens 170 satisfies:

[0069]

[0070] Where Z is the distance vector height from the vertex of the aspheric surface when the aspheric surface is at a height of y along the optical axis; c = 1 / R, R represents the paraxial curvature radius of the mirror; K is the cone coefficient; A, B, C, D, E, and F are high-order aspheric coefficients, where the units of Z, R, and y are all mm.

[0071] For example, Table 2 describes in detail the aspheric coefficients of each lens in the first embodiment in a feasible implementation manner.

[0072] Table 2 Aspheric coefficients in wide-angle lenses

[0073] Serial number A B C D E F G 1 4.45E-04 1.31E-04 1.43E-06 -5.85E-07 -2.17E-08 7.04E-09 -3.11E-10 2 -6.92E-03 3.18E-04 1.94E-04 -4.02E-05 -3.18E-06 2.01E-06 -1.79E-07 3 9.64E-03 -1.50E-03 -3.27E-04 -9.29E-05 7.15E-06 4.77E-06 -4.97E-07 4 2.58E-02 1.84E-04 -2.83E-03 3.60E-04 -1.39E-05 1.56E-05 -2.36E-06 7 -1.15E-02 3.07E-03 -5.66E-03 9.49E-04 1.09E-03 -1.86E-04 -6.18E-05 8 -1.55E-05 -7.59E-03 1.16E-03 3.05E-04 7.41E-05 -1.12E-05 -1.41E-05 10 2.00E-02 -1.46E-02 4.41E-03 -8.45E-04 8.14E-05 -1.14E-04 3.19E-05 11 -1.01E-02 -7.97E-03 3.37E-03 -1.50E-03 2.52E-04 -5.64E-06 -1.05E-06 12 -3.98E-02 -6.14E-04 3.79E-03 -1.50E-03 2.14E-04 -3.21E-06 1.07E-06 13 -2.54E-02 6.06E-03 -4.51E-04 -1.71E-06 -3.97E-06 8.71E-07 1.24E-08 14 7.76E-03 2.96E-04 -2.18E-05 7.11E-06 -1.67E-06 -4.68E-07 6.56E-08 15 9.56E-03 8.13E-04 2.84E-04 -3.12E-05 -1.94E-06 2.09E-07 -6.92E-09

[0074] Among them, 4.45E-04 means that the coefficient A of the face number 1 is 4.45*10 -3 , and so on.

[0075] The wide-angle lens of the first embodiment achieves the following technical indicators:

[0076] Entrance diameter: N=1.48;

[0077] Aperture: F=2.0;

[0078] TTL / BFL=3.54;

[0079] Field of view: 2w ≥ 95°;

[0080] Optical distortion: F-Tan (Theta) <3%;

[0081] Resolution: Compatible with 8-megapixel high-resolution CCD or CMOS cameras.

[0082] Further, Figure 3 This is a spherical aberration curve diagram of a wide-angle lens provided in Example 1 of the present invention, such as Figure 3 As shown, the spherical aberration of the wide-angle lens at different wavelengths (0.436μm, 0.486μm, 0.546μm, 0.587μm and 0.656μm) is within 0.05mm, and the curves at different wavelengths are relatively concentrated, indicating that the axial aberration of the wide-angle lens is very small. Therefore, it can be seen that the wide-angle lens provided by the embodiment of the present invention can better correct aberrations.

[0083] Figure 4 This is a ray fan diagram of a wide-angle lens provided in the first embodiment of the present invention, such as Figure 4 As shown in the figure, the imaging range of light of different wavelengths (0.436μm, 0.486μm, 0.546μm, 0.588μm and 0.656μm) at different field angles of view of the wide-angle lens is all within 50μm and the curves are very concentrated, ensuring that the aberrations in different field areas are small, which also shows that the wide-angle lens can better correct the aberrations of the optical system.

[0084] Figure 5 This is a point diagram of a wide-angle lens provided in the first embodiment of the present invention, such as Figure 5As shown, the RMS radius of each field of view is less than 3.5 μm, indicating that the wide-angle lens provided in the first embodiment has a high image quality.

[0085] Figure 6 The vertical axis chromatic aberration of a wide-angle lens provided in the first embodiment of the present invention is: Figure 7 This is a field curvature distortion diagram of a wide-angle lens provided in Example 1 of the present invention. Figure 8 This is an MTF diagram of a wide-angle lens provided in Example 1 of the present invention, combined with Figure 6-8 As shown, the wide-angle lens provided by the embodiment of the present invention has small vertical axis chromatic aberration and small field curvature, that is, when imaging, the difference between the image quality at the center and the image quality at the periphery is small; the image quality is high and can achieve 4K high-definition image quality.

[0086] Example 2

[0087] Continue to refer Figure 2 The wide-angle lens provided in Example 2 of the present invention includes a first lens 110, a second lens 120, a third lens 130, a fourth lens 140, a fifth lens 150, a sixth lens 160, and a seventh lens 170, arranged in sequence along the optical axis from the object plane to the image plane. A second aperture 190 is provided in the optical path between the third lens 130 and the fourth lens 140. Table 3 shows the optical physical parameters of each lens in the wide-angle lens provided in Example 2, including surface type, curvature radius, thickness, and material.

[0088] Table 3 Optical and physical parameters of wide-angle lens

[0089] Surface number Surface type Radius of curvature thickness Materials (nd) K-Factor 1 Aspheric -20.9 0.6 1.53 -172.5 2 Aspheric 3.6 0.4 0.16 3 Aspheric 3.4 1.1 1.66 0.9 4 Aspheric 3.1 1.0 1.1 5 Aspheric -8.1 1.1 1.66 -0.0023 6 Aspheric -5.1 0.2 -38.4 STO PL Infinity 0.03 8 Aspheric 34.4 0.9 1.53 -0.2 9 Aspheric -8.5 0.04 -0.00036 10 spherical surface -9.3 1.3 1.69 10.9 11 spherical surface -2.6 0.1 -6.8 12 Aspheric 5.4 0.5 1.67 -49.3 13 Aspheric 2.0 0.3 -8.3 14 Aspheric -13.5 1.6 1.53 30.4 15 Aspheric -2.2 2.8 -0.8

[0090] The surface numbers are numbered according to the order of the lens surfaces. For example, surface numbers 1 and 2 are the object-side and image-side surfaces of the first lens 110, respectively; surface numbers 3 and 4 are the object-side and image-side surfaces of the second lens 120, respectively; and so on. The radius of curvature represents the degree of curvature of the lens surface; a positive value indicates that the surface is curved toward the image plane, while a negative value indicates that the surface is curved toward the object plane. The thickness represents the axial distance from the center of the current surface to the next surface, and the units of both the radius of curvature and thickness are millimeters (mm).

[0091] Based on the above implementation, the fifth lens 150 may optionally be a glass aspheric lens, and the first lens 110, the second lens 120, the third lens 130, the fourth lens 140, the sixth lens 160, and the seventh lens 170 may all be plastic aspheric lenses. The wide-angle lens provided in this embodiment of the present invention also includes a second aperture 190 (STO). The addition of this second aperture 190 adjusts the propagation direction of the light beam, thereby improving imaging quality. The second aperture 190 may be located in the optical path between the third lens 130 and the fourth lens 140, but this embodiment of the present invention does not limit the specific location of the second aperture 190.

[0092] The aspheric surface shape equation Z of the first lens 110, the second lens 120, the third lens 130, the fourth lens 140, the fifth lens 150, the sixth lens 160, and the seventh lens 170 satisfies:

[0093]

[0094] Where Z is the distance vector height from the vertex of the aspheric surface when the aspheric surface is at a height of y along the optical axis; c = 1 / R, R represents the paraxial curvature radius of the mirror; K is the cone coefficient; A, B, C, D, E, and F are high-order aspheric coefficients, where the units of Z, R, and y are all mm.

[0095] For example, Table 4 details the aspheric coefficients of each lens in the second embodiment in a feasible implementation manner.

[0096] Table 4 Aspheric coefficients in wide-angle lenses

[0097] Serial number A B C D E F G 1 2.84E-03 1.86E-04 -3.62E-06 -9.37E-07 3.80E-08 1.85E-10 2.84E-03 2 3.37E-03 -1.11E-03 1.67E-04 4.18E-05 1.02E-06 -5.31E-07 3.37E-03 3 2.38E-02 -2.66E-03 -1.85E-04 1.76E-05 6.01E-06 -2.31E-06 2.38E-02 4 5.48E-02 3.66E-03 -4.36E-03 -2.51E-04 -1.15E-04 5.38E-05 5.48E-02 5 1.68E-02 -7.79E-03 7.59E-04 -1.14E-05 -1.42E-05 1.20E-06 1.68E-02 6 -1.11E-02 3.84E-03 6.94E-04 -1.46E-03 2.85E-04 -1.77E-05 -1.11E-02 8 -7.28E-03 -2.57E-04 -7.32E-03 5.76E-03 -2.44E-03 0.00E+00 -7.28E-03 9 -3.22E-02 -1.57E-03 -5.18E-04 -1.34E-03 2.82E-04 0.00E+00 -3.22E-02 10 1.73E-02 -1.36E-02 3.46E-03 -1.75E-03 9.94E-05 9.34E-05 1.73E-02 11 1.44E-03 -8.72E-03 2.82E-03 -1.33E-03 2.65E-04 -1.38E-05 1.44E-03 12 -4.69E-02 -4.85E-03 4.65E-03 -1.48E-03 1.68E-04 3.39E-06 -4.69E-02 13 -3.87E-02 6.39E-03 -4.92E-04 8.19E-06 -9.41E-07 4.58E-07 -3.87E-02 14 6.54E-03 7.56E-04 -3.29E-05 2.20E-05 -4.75E-06 5.16E-07 6.54E-03 15 7.37E-03 1.17E-04 4.63E-04 4.75E-06 -1.32E-05 9.34E-07 7.37E-03

[0098] Among them, 2.84E-03 means that the coefficient A of the face number 1 is 2.84*10 -3 , and so on.

[0099] The wide-angle lens of the second embodiment achieves the following technical indicators:

[0100] Entrance diameter: N=1.5;

[0101] Aperture: F=2.0;

[0102] TTL / BFL=3.17;

[0103] Field of view: 2w ≥ 95°;

[0104] Optical distortion: F-Tan (Theta) <3%;

[0105] Resolution: Compatible with 8-megapixel high-resolution CCD or CMOS cameras.

[0106] Further, Figure 9 This is a spherical aberration curve diagram of a wide-angle lens provided in Example 2 of the present invention, such as Figure 9 As shown, the spherical aberration of the wide-angle lens at different wavelengths (0.436μm, 0.486μm, 0.546μm, 0.587μm and 0.656μm) is within 0.05mm, and the curves at different wavelengths are relatively concentrated, indicating that the axial aberration of the wide-angle lens is very small. Therefore, it can be seen that the wide-angle lens provided by the embodiment of the present invention can better correct aberrations.

[0107] Figure 10 This is a ray fan diagram of a wide-angle lens provided in the second embodiment of the present invention, such as Figure 10 As shown in the figure, the imaging range of light of different wavelengths (0.436μm, 0.486μm, 0.546μm, 0.588μm and 0.656μm) at different field angles of view of the wide-angle lens is all within 50μm and the curves are very concentrated, ensuring that the aberrations in different field areas are small, which also shows that the wide-angle lens can better correct the aberrations of the optical system.

[0108] Figure 11 This is a point diagram of a wide-angle lens provided in the second embodiment of the present invention, such as Figure 11 As shown, the RMS radius of each field of view is less than 3.5 μm, indicating that the wide-angle lens provided in the second embodiment has a high image quality.

[0109] Figure 12 The vertical axis chromatic aberration of a wide-angle lens provided in the second embodiment of the present invention is: Figure 13 This is a field curvature distortion diagram of a wide-angle lens provided in Example 2 of the present invention. Figure 14 This is an MTF diagram of a wide-angle lens provided in Example 2 of the present invention, combined with Figure 12-14 As shown, the wide-angle lens provided by the embodiment of the present invention has small vertical axis chromatic aberration and small field curvature, that is, when imaging, the difference between the image quality at the center and the image quality at the periphery is small; the image quality is high and can achieve 4K high-definition image quality.

[0110] In summary, the wide-angle lens provided by the embodiment of the present invention realizes a low-cost, ultra-high-definition, ultra-low distortion and wide-angle fixed-focus lens with no obvious purple fringing. The design adopts a 7-piece structure. Under the premise of low cost, it can achieve 4K high-definition image quality, optical distortion is less than 3%, and the field of view angle meets 80°-100°. The seven lenses adopt a glass-plastic hybrid structure, so that the wide-angle lens can meet the demand of not defocusing in an environment of -20℃-60℃.

[0111] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in detail through the above embodiments, the present invention is not limited to the above embodiments and may include many other equivalent embodiments without departing from the concept of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. A wide-angle lens, characterized in that: comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens and a seventh lens arranged in sequence along the optical axis from the object plane to the image plane; The first lens and the sixth lens are both negative power lenses, the third lens, the fourth lens, the fifth lens and the seventh lens are all positive power lenses, and the second lens is a negative power lens or a positive power lens; The focal length of the first lens is f1, the focal length of the second lens is f2, the focal length of the third lens is f3, the focal length of the fourth lens is f4, the focal length of the fifth lens is f5, the focal length of the sixth lens is f6, the focal length of the seventh lens is f7, and the focal length of the wide-angle lens is f, wherein: 0.3≤|f1 / f|≤2.6; |f2 / f|≥2; 2.3≤|f3 / f|≤7.2; |f4 / f|≥0.8; 0.67≤|f5 / f|≤2.94; 0.32≤|f6 / f|≤2.77; |f7 / f|≥0.16; The object-side surface of the fifth lens has a curvature radius of R51, and the image-side surface of the fifth lens has a curvature radius of R52, wherein |R51 / R52|≥2.23; The first lens to the seventh lens are fixed in a lens barrel.

2. The wide-angle lens according to claim 1, wherein: The second lens is a negative power lens; the third lens is a glass spherical lens; the first lens, the second lens, the fourth lens, the fifth lens, the sixth lens, and the seventh lens are all plastic aspherical lenses; the wide-angle lens further includes a first aperture stop, which is disposed in the optical path between the fourth lens and the fifth lens; Alternatively, the second lens is a positive power lens; the fifth lens is a glass aspheric lens, and the first lens, the second lens, the third lens, the fourth lens, the sixth lens and the seventh lens are all plastic aspheric lenses; the wide-angle lens further includes a second aperture, which is arranged in the optical path between the third lens and the fourth lens.

3. The wide-angle lens according to claim 1, wherein: The refractive index of the first lens is n1; the refractive index of the second lens is n2, and the Abbe number is v2; the refractive index of the third lens is n3, and the Abbe number is v3; the refractive index of the fourth lens is n4, and the Abbe number is v4; the refractive index of the seventh lens is n7; wherein: 1.43≤n1≤1.9; 1.50≤n2≤1.75, 19≤v2≤56; n3≥1.43, v3≥18.6; 1.53≤n4≤1.68, v4≥19; 1.53≤n7≤1.

67.

4. The wide-angle lens according to claim 1, wherein: The sag of the object-side surface of the first lens is SAG11, and the sag of the image-side surface of the first lens is SAG12, wherein 0.08≤|SAG11 / SAG12|≤1.

5.

5. The wide-angle lens according to claim 1, wherein: The object-side surface of the second lens has a curvature radius of R21, where |R21|≥1.

42.

6. The wide-angle lens according to claim 1, wherein: The center thickness of the fourth lens is CT4, and the center thickness of the fifth lens is CT5, wherein |CT4 / CT5|≤1.

88.

7. The wide-angle lens according to claim 1, wherein: The fourth lens is a meniscus lens.

8. The wide-angle lens according to claim 1, wherein: The distance from the optical axis center of the image-side surface of the seventh lens to the image plane is BFL, and the distance from the optical axis center of the object-side surface of the first lens to the image plane is TTL, wherein 0.11≤BFL / TTL≤0.

89.

9. The wide-angle lens according to claim 1, wherein: The aperture of the wide-angle lens is F, wherein 0.6≤f / F≤2.8.

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