An ultra-wide-angle lens

Abstract

An embodiment of the present invention discloses an ultra-wide-angle lens. The lens includes 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 from the object side to the image side along the optical axis; the first lens is a meniscus-shaped plastic aspheric lens or a glass spherical lens with negative optical power; the second lens is a meniscus-shaped plastic aspheric lens with negative optical power; the third lens is a biconcave plastic aspheric lens with negative optical power; the fourth lens is a biconvex glass spherical lens with positive optical power; the fifth lens is a biconvex plastic aspheric lens with positive optical power; the sixth lens is a biconcave plastic aspheric lens with negative optical power; and the seventh lens is a biconvex plastic aspheric lens with positive optical power. The embodiment of the present invention can reduce production costs, achieve low distortion, low distortion, and miniaturization, and can also achieve a field of view of 120°-175° and an F-Theta distortion of less than 12%.

Description

Technical Field

[0001] The embodiments of the present invention relate to optical lens technology, and in particular to an ultra-wide-angle lens. Background Art

[0002] With the advancement of electronic technology and the increasing demand for lens applications, today's lenses, in addition to a wide field of view, are required to exhibit low distortion and high brightness. For example, in surveillance systems, ultra-wide-angle performance is sought to capture more footage and cover a wider area. However, currently available ultra-wide-angle lenses are mostly made of glass aspherical lenses, which are difficult to manufacture and have high production costs. Furthermore, existing ultra-wide-angle lenses still suffer from imaging issues, including blind spots and poor clarity. In particular, when the field of view exceeds 120°, distortion is excessive, resulting in severe image distortion, which affects surveillance effectiveness. Summary of the Invention

[0003] The present invention provides an ultra-wide-angle lens, which can achieve an ultra-wide angle while ensuring low distortion and being able to well correct various aberrations, thereby reducing the number of glass aspherical lenses and lowering manufacturing and production costs.

[0004] In a first aspect, an embodiment of the present invention provides an ultra-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 from the object side to the image side along the optical axis;

[0005] The first lens is a meniscus-shaped plastic aspheric lens or a glass spherical lens with negative optical power; the second lens is a meniscus-shaped plastic aspheric lens with negative optical power; the third lens is a biconcave plastic aspheric lens with negative optical power; the fourth lens is a biconvex glass spherical lens with positive optical power; the fifth lens is a biconvex plastic aspheric lens with positive optical power; the sixth lens is a biconcave plastic aspheric lens with negative optical power; and the seventh lens is a biconvex plastic aspheric lens with positive optical power.

[0006] Optionally, the aperture F# of the ultra-wide-angle lens satisfies the relationship: 1.6≤F#≤2.4.

[0007] Optionally, the focal length of the ultra-wide-angle lens is f, and the focal lengths of the first to seventh lenses are f1, f2, f3, f4, f5, f6, and f7, respectively; the focal lengths of the first to seventh lenses and the ultra-wide-angle lens satisfy the following relationship:

[0008] 1.05≤|f1 / f|≤2.5;

[0009] 3.5≤|f2 / f|;

[0010] 3.0≤|f3 / f|;

[0011] 1.3≤|f4 / f|≤2.5;

[0012] |f5 / f|≤1.98;

[0013] 0.8≤|f6 / f|≤1.7;

[0014] 1.45≤|f 7 / f|.

[0015] Optionally, the refractive index n1 of the first lens is ≥1.5.

[0016] Optionally, the focal length f3 of the third lens and the distance TTL from the front surface vertex of the first lens to the image plane satisfy the relationship: |TTL / f3|≤2.48.

[0017] Optionally, the refractive index n4 of the fourth lens is ≥1.8, and the Abbe number V4 of the fourth lens is ≥25.

[0018] Optionally, a curvature radius R1 of the image side surface of the first lens and a curvature radius R4 of the image side surface of the fourth lens satisfy the relationship: R1 / R4≤0.45.

[0019] Optionally, a curvature radius R5 of the object-side surface of the fifth lens and a curvature radius R6 of the object-side surface of the sixth lens satisfy the relationship: 0.05≤|R5 / R6|.

[0020] Optionally, a curvature radius R7 of the image-side surface of the seventh lens element satisfies the relationship: |R7|≤6.6.

[0021] Optionally, a center thickness CT6 of the sixth lens on the optical axis and a center thickness CT7 of the seventh lens on the optical axis satisfy the relationship: 0.17≤CT6 / CT7≤0.56.

[0022] An ultra-wide-angle lens provided by an embodiment of the present invention realizes a 2G5P or 1G6P ultra-wide-angle lens structure by arranging a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens in sequence along the optical axis from the object side to the image side; and arranging the first lens to be a meniscus-shaped plastic aspherical lens or a glass spherical lens with negative optical power; the second lens to be a meniscus-shaped plastic aspherical lens with negative optical power; the third lens to be a biconcave plastic aspherical lens with negative optical power; the fourth lens to be a biconvex glass spherical lens with positive optical power; the fifth lens to be a biconvex plastic aspherical lens with positive optical power; the sixth lens to be a biconcave plastic aspherical lens with negative optical power; and the seventh lens to be a biconvex plastic aspherical lens with positive optical power. The embodiments of the present invention can realize an ultra-wide-angle lens composed of two glass lenses and five plastic lenses or one glass lens and six plastic lenses. This not only reduces the number of glass aspheric lenses, reduces the difficulty of manufacturing lenses, and effectively improves production costs, but also realizes the low distortion, low distortion, and miniaturization characteristics of the ultra-wide-angle lens, so that the field of view angle 2w is within the range of 120°-175°, the F-Theta distortion is less than -12%, the total optical length TTL is less than 17.5mm, and it can also meet infrared confocality and ensure that it can operate at -40°C to +80°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 1 is a schematic structural diagram of an ultra-wide-angle lens provided by an embodiment of the present invention;

[0024] Figure 2 yes Figure 1 Field curvature graph of the ultra-wide-angle lens shown;

[0025] Figure 3 yes Figure 1 The distortion curve of the ultra-wide-angle lens shown;

[0026] Figure 4 yes Figure 1 The ray fan diagram of the ultra-wide-angle lens shown;

[0027] Figure 5 yes Figure 1 Axial aberrations of the ultra-wide-angle lens shown;

[0028] Figure 6 yes Figure 1 Off-axis chromatic aberration of the ultra-wide-angle lens shown;

[0029] Figure 7 yes Figure 1 Spot diagram of the ultra-wide-angle lens shown;

[0030] Figure 8 is a schematic structural diagram of another ultra-wide-angle lens provided by an embodiment of the present invention;

[0031] Figure 9 yes Figure 8 Field curvature graph of the ultra-wide-angle lens shown;

[0032] Figure 10 yes Figure 8 The distortion curve of the ultra-wide-angle lens shown;

[0033] Figure 11 yes Figure 8 The ray fan diagram of the ultra-wide-angle lens shown;

[0034] Figure 12 yes Figure 8 Axial aberrations of the ultra-wide-angle lens shown;

[0035] Figure 13 yes Figure 8 Off-axis chromatic aberration of the ultra-wide-angle lens shown;

[0036] Figure 14 yes Figure 8 Spot diagram of the ultra-wide-angle lens shown. DETAILED DESCRIPTION

[0037] 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.

[0038] Figure 1 is a schematic structural diagram of an ultra-wide-angle lens provided by an embodiment of the present invention, with reference to Figure 1 The ultra-wide-angle lens comprises a first lens 11, a second lens 12, a third lens 13, a fourth lens 14, a fifth lens 15, a sixth lens 16, and a seventh lens 17, which are arranged in sequence from the object side to the image side along the optical axis;

[0039] The first lens 11 is a meniscus-shaped plastic aspheric lens or a glass spherical lens with negative optical power; the second lens 12 is a meniscus-shaped plastic aspheric lens with negative optical power; the third lens 13 is a biconcave plastic aspheric lens with negative optical power; the fourth lens 14 is a biconvex glass spherical lens with positive optical power; the fifth lens 15 is a biconvex plastic aspheric lens with positive optical power; the sixth lens 16 is a biconcave plastic aspheric lens with negative optical power; and the seventh lens 17 is a biconvex plastic aspheric lens with positive optical power.

[0040] Among them, it can be understood that the optical power is equal to the difference between the convergence of the image-side beam and the convergence of the object-side beam, which represents 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. Figure 1 In the illustrated ultra-wide-angle lens, the first lens 11, the second lens 12, the third lens 13, and the sixth lens 6 are configured with negative optical power, while the fourth lens 14, the fifth lens 15, and the seventh lens 17 are configured with positive optical power. This allows the first lens 11 to increase the field of view, while the other lenses converge and diverge light while correcting for on-axis and off-axis aberrations, thereby improving image quality and achieving a lens with a large target area and a wide field of view. Specifically, the negative optical power of the first lens 11, the second lens 12, and the third lens 13 can be used to control the optical system's angle of incidence, achieving a wide field of view. Furthermore, the coordinated optical power of the other lenses can correct for aberrations in the ultra-wide-angle lens, ensuring high resolution.

[0041] On the basis of the above, the second lens 12, the third lens 13, the fifth lens 15, the sixth lens 16 and the seventh lens 17 are configured to use plastic aspherical lenses, while the first lens 11 is configured to use a plastic aspherical lens or a glass spherical lens, and the fourth lens 14 is configured to use a glass spherical lens. Two glass lenses and five plastic lenses or one glass lens and six plastic lenses can be used to achieve a mixture of glass lenses and plastic lenses and mutual compensation. In other words, aspherical lenses can be made from plastic lenses, which can better correct axial chromatic aberration and achieve day and night confocal function. In addition, the use of plastic to prepare aspherical surfaces can reduce manufacturing difficulty and thus production costs. In addition, for the first lens 11 and the fourth lens 14, which have higher imaging quality requirements, the use of glass spherical lenses can reduce the temperature sensitivity of the entire ultra-wide-angle lens, ensuring that the lens can meet stable imaging requirements at high or low temperatures, and ensuring that the resolution meets imaging requirements when used in an environment of -40°C to +80°C. It should be noted that in the ultra-wide-angle lens provided in the embodiment of the present invention, the specific shapes of the lenses, such as the meniscus-shaped first lens 11 and the second lens 12 and the biconcave-shaped third lens 13, are intended to cooperate with each other to better correct on-axis aberrations and off-axis chromatic aberrations, reduce distortion, optimize imaging quality while meeting the ultra-wide-angle requirement, and ensure image clarity, under the premise of determining the optical power.

[0042] An ultra-wide-angle lens provided by an embodiment of the present invention realizes a 2G5P or 1G6P ultra-wide-angle lens structure by arranging a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens in sequence along the optical axis from the object side to the image side; and arranging the first lens to be a meniscus-shaped plastic aspherical lens or a glass spherical lens with negative optical power; the second lens to be a meniscus-shaped plastic aspherical lens with negative optical power; the third lens to be a biconcave plastic aspherical lens with negative optical power; the fourth lens to be a biconvex glass spherical lens with positive optical power; the fifth lens to be a biconvex plastic aspherical lens with positive optical power; the sixth lens to be a biconcave plastic aspherical lens with negative optical power; and the seventh lens to be a biconvex plastic aspherical lens with positive optical power. The embodiments of the present invention can realize an ultra-wide-angle lens composed of two glass lenses and five plastic lenses or one glass lens and six plastic lenses. This not only reduces the number of glass aspheric lenses, reduces the difficulty of manufacturing lenses, and effectively improves production costs, but also realizes the low distortion, low distortion, and miniaturization characteristics of the ultra-wide-angle lens, so that the field of view angle 2w is within the range of 120°-175°, the F-Theta distortion is less than -12%, the total optical length TTL is less than 17.5mm, and it can also meet infrared confocality and ensure that it can operate at -40°C to +80°C.

[0043] For other lenses in the fisheye lens, the embodiment of the present invention also provides a specific implementation method. Figure 1 Specifically, the aperture F# of the ultra-wide-angle lens satisfies the relationship: 1.6≤aperture F#≤2.4.

[0044] Furthermore, the focal lengths of the first to seventh lenses and the ultra-wide-angle lens may be set to satisfy the following relationship:

[0045] 1.05≤|f1 / f|≤2.5;

[0046] 3.5≤|f2 / f|;

[0047] 3.0≤|f3 / f|;

[0048] 1.3≤|f4 / f|≤2.5;

[0049] |f5 / f|≤1.98;

[0050] 0.8≤|f6 / f|≤1.7;

[0051] 1.45≤|f7 / f|;

[0052] Among them, the focal lengths of the first to seventh lenses are f1, f2, f3, f4, f5, f6, and f7 respectively.

[0053] The focal length of first lens 11 can be adjusted to control the field of view of the entire ultra-wide-angle lens. Furthermore, the refractive index n1 of first lens 11 can be set to ≥ 1.5. In this case, the high refractive index of first lens 11, combined with the use of low-abbetic coefficient materials, can help the lens accommodate wide-angle light and achieve an ultra-wide viewing angle.

[0054] The second lens 12 is used to smooth the light emitted by the first lens 11 and reduce the magnitude of the incident angle; while the third lens 13 is used to control the total optical length of the entire ultra-wide-angle lens by setting the focal length, which helps to achieve miniaturization of the lens. For the third lens 13, the focal length f3 of the third lens and the distance TTL from the front surface vertex of the first lens to the image plane can be optionally set to satisfy the relationship: |TTL / f3|≤2.48. At this time, the relationship between the focal length of the third lens 13 and the total optical length TTL can be used to limit the overall proportion and overall size of the ultra-wide-angle lens, ensuring that the ultra-wide-angle lens meets the size requirements during actual assembly, which helps to achieve miniaturization.

[0055] The fourth, fifth, sixth, and seventh lenses 14, 15, 16, and 17 are primarily responsible for correcting field curvature and astigmatism. Optionally, the refractive index n4 and Abbe number V4 of the fourth lens 14 can be set to satisfy n4 ≥ 1.8 and V4 ≥ 25. In this case, the high dispersion and high refractive index of the fourth lens 14 compensate for chromatic aberration while also minimizing the radius of curvature of the lens, thereby helping to correct for lens tolerance sensitivity.

[0056] Furthermore, the image side surface curvature radius R1 of the first lens and the image side surface curvature radius R4 of the fourth lens may satisfy the relationship: R1 / R4≤0.45; the object side surface curvature radius R5 of the fifth lens and the object side surface curvature radius R6 of the sixth lens may satisfy the relationship: 0.05≤|R5 / R6|; and the image side surface curvature radius R7 of the seventh lens may satisfy the relationship: |R7|≤6.6.

[0057] Reasonable restrictions on the curvature radii and their proportional relationships of the first lens element 11, the fourth lens element 14, the fifth lens element 15, the sixth lens element 16, and the seventh lens element 17 can ensure coordination of the optical powers of the lenses, thereby contributing to better image quality, a smaller overall focal length of the lens, and a larger aperture. This also helps reduce the incident angle of light, making it less than or equal to 16°.

[0058] During the design of this ultra-wide-angle lens, the relevant parameters of each lens can be adjusted based on the actual lens size requirements to meet the dimensional requirements during actual assembly. Based on the ultra-wide-angle lens provided in the above embodiment, the center thickness CT6 of the sixth lens 16 and the center thickness CT7 of the seventh lens 17 on the optical axis can be set to satisfy the relationship: 0.17≤CT6 / CT7≤0.56. By limiting the thickness ratio of the sixth lens 16 and the seventh lens 17, it is possible to ensure that the sixth lens 16 and the seventh lens 17 compensate for each other's aberrations while appropriately limiting the lens size, thereby contributing to lens miniaturization.

[0059] The following describes the ultra-wide-angle lens using two specific embodiments. Figure 1 As shown, the ultra-wide-angle lens includes a first lens 11, a second lens 12, a third lens 13, a fourth lens 14, a fifth lens 15, a sixth lens 16, and a seventh lens 17, which are arranged in sequence from the object side to the image side along the optical axis;

[0060] The first lens 11 is a meniscus-shaped glass spherical lens with negative optical power; the second lens 12 is a meniscus-shaped plastic aspherical lens with negative optical power; the third lens 13 is a biconcave plastic aspherical lens with negative optical power; the fourth lens 14 is a biconvex glass spherical lens with positive optical power; the fifth lens 15 is a biconvex plastic aspherical lens with positive optical power; the sixth lens 16 is a biconcave plastic aspherical lens with negative optical power; and the seventh lens 17 is a biconvex plastic aspherical lens with positive optical power.

[0061] In this embodiment, the design values of the first lens 11 to the seventh lens 17 are shown in Table 1 below.

[0062] Table 1 shows a design value of the ultra-wide-angle lens (f=2.6mm; aperture F#2.0):

[0063] Surface number Face shape Radius of curvature thickness Refractive index Fitting cone coefficient K S1 Standard surface 23.8 0.6 1.816 S2 Standard surface 3.26 1.46 S3 Aspheric 6.58 0.6 1.53 3.90 S4 Aspheric 3.00 1.19 -0.50 S5 Aspheric -19.47 0.6 1.66 60.00 S6 Aspheric 9.55 0.02 0 S7 Standard surface 9.26 2.03 2.05 S8 Standard surface -7.92 -0.01 aperture PL Infinity 2.03 S10 Aspheric 7.02 1.55 1.53 2.62 S11 Aspheric -4.17 0.08 -9.99 S12 Aspheric 48.1 0.59 1.66 -154.9 S13 Aspheric 2.50 0.16 -4.32 S14 Aspheric 4.04 2.13 1.53 -1.36 S15 Aspheric -4.36 0.87 0.55

[0064] The surface numbers in Table 1 are numbered according to the order of the surfaces of each lens, where "S1" represents the front surface of the first lens, "S2" represents the back surface of the first lens, and so on. The radius of curvature represents the degree of curvature of the lens surface, with a positive value indicating that the surface is curved toward the image plane, and a negative value indicating that the surface is curved toward the object plane. The thickness represents the axial distance from the current surface to the center of the next surface. The refractive index represents the ability of the material between the current surface and the next surface to deflect light. A blank space represents the current position as air, with a refractive index of 1.

[0065] The aspheric cone coefficient can be defined by the following aspheric formula, but is not limited to the following expression method:

[0066]

[0067] Among them, z is the axial sagittal height of the aspheric surface in the Z direction; r is the height of the aspheric surface; c is the curvature of the fitted sphere, which is the inverse of the curvature radius; k is the fitting cone coefficient; AG is the coefficient of the 4th, 6th, 8th, 10th, 12th, 14th, and 16th order terms of the aspheric polynomial.

[0068] The aspheric surface parameters in this embodiment are shown in Table 2:

[0069] Table 2 shows a design value of the aspheric coefficient in the ultra-wide-angle lens.

[0070] Surface number A B C D E F 3 1.22E-03 -1.82E-03 1.84E-04 1.23E-05 -5.46E-06 3.31E-07 4 1.00E-02 -1.53E-03 -1.05E-04 1.27E-04 2.79E-06 -4.53E-06 5 5.50E-03 -1.04E-03 2.39E-04 -5.28E-05 2.68E-05 -4.80E-06 6 2.16E-03 -2.64E-05 -7.40E-04 3.81E-04 -8.06E-05 5.96E-06 10 1.16E-03 1.39E-03 -3.75E-04 1.37E-04 -2.83E-05 2.47E-06 11 -6.73E-03 4.42E-03 -9.39E-04 1.38E-04 -2.74E-05 2.55E-06 12 -2.52E-02 6.50E-03 -6.04E-04 -2.91E-04 7.06E-05 -5.93E-06 13 -5.49E-03 7.00E-04 9.59E-05 -6.50E-05 1.26E-05 -1.10E-06 14 -7.40E-04 -3.06E-03 6.81E-04 -3.39E-05 -2.04E-06 -2.79E-09 15 1.09E-03 -4.70E-05 -3.38E-05 1.87E-05 -3.76E-06 3.98E-07

[0071] Figure 2 yes Figure 1 Field curvature graph of the ultra-wide-angle lens shown; Figure 3 yes Figure 1 The distortion curve of the ultra-wide-angle lens shown; Figure 4 yes Figure 1 The ray fan diagram of the ultra-wide-angle lens shown; Figure 5 yes Figure 1 Axial aberrations of the ultra-wide-angle lens shown; Figure 6 yes Figure 1 Off-axis chromatic aberration of the ultra-wide-angle lens shown; Figure 7 yes Figure 1 The spot diagram of the ultra-wide-angle lens shown in Figure 1 is Figure 2 It can be seen that the field curvature in the meridian and sagittal directions of the ultra-wide-angle lens is between ±0.1mm. Figure 3 It can be seen that the maximum distortion of the ultra-wide-angle lens is within -12%. Figure 4 It can be seen that the imaging range of different wavelengths at different field angles is within ±20μm; Figure 5 and Figure 6 It can be seen that the axial chromatic aberration produced by light of different wavelengths is within ±0.02mm, and the vertical chromatic aberration is within the Airy disk. Figure 7 It can be seen that the Airy disk radius at different positions in the field of view is less than 3 μm. From the above, it can be seen that the ultra-wide-angle lens provided by the embodiment of the present invention can not only correct axial aberration and vertical chromatic aberration, but also reduce distortion and achieve optimization of imaging.

[0072] Figure 8 is a schematic structural diagram of another ultra-wide-angle lens provided by an embodiment of the present invention, with reference to Figure 8 The ultra-wide-angle lens comprises a first lens 11, a second lens 12, a third lens 13, a fourth lens 14, a fifth lens 15, a sixth lens 16 and a seventh lens 17, which are arranged in sequence from the object side to the image side along the optical axis;

[0073] The first lens 11 is a meniscus-shaped plastic aspheric lens with negative optical power; the second lens 12 is a meniscus-shaped plastic aspheric lens with negative optical power; the third lens 13 is a biconcave plastic aspheric lens with negative optical power; the fourth lens 14 is a biconvex glass spherical lens with positive optical power; the fifth lens 15 is a biconvex plastic aspheric lens with positive optical power; the sixth lens 16 is a biconcave plastic aspheric lens with negative optical power; and the seventh lens 17 is a biconvex plastic aspheric lens with positive optical power.

[0074] In this embodiment, the design values of the first lens 21 to the seventh lens 27 are shown in Table 3 below.

[0075] Table 3 shows a design value of the ultra-wide-angle lens (f=2.62mm; aperture F#2.0):

[0076]

[0077]

[0078] The aspheric surface parameters in this embodiment are shown in Table 4:

[0079] Table 4 shows a design value of the aspheric coefficient in the ultra-wide-angle lens.

[0080]

[0081]

[0082] Figure 9 yes Figure 8 Field curvature graph of the ultra-wide-angle lens shown; Figure 10 yes Figure 8 The distortion curve of the ultra-wide-angle lens shown; Figure 11 yes Figure 8 The ray fan diagram of the ultra-wide-angle lens shown; Figure 12 yes Figure 8 Axial aberrations of the ultra-wide-angle lens shown; Figure 13 yes Figure 8 Off-axis chromatic aberration of the ultra-wide-angle lens shown; Figure 14 yes Figure 8 The spot diagram of the ultra-wide-angle lens shown; Figure 9 It can be seen that the field curvature in the meridian and sagittal directions of the ultra-wide-angle lens is between ±0.15mm. Figure 10 It can be seen that the maximum distortion of the ultra-wide-angle lens is within -12%. Figure 11 It can be seen that the imaging range of different wavelengths at different field angles is within ±20μm; Figure 12 and Figure 13It can be seen that the axial chromatic aberration produced by light of different wavelengths is within ±0.02mm, and the vertical chromatic aberration is within ±4μm. Figure 14 It can be seen that the Airy disk radius at different field of view positions is less than 5 μm. From the above, it can be seen that the ultra-wide-angle lens provided by the embodiment of the present invention can not only correct axial aberration and vertical chromatic aberration, but also reduce distortion and achieve optimization of imaging.

[0083] Note that the above are only preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments, combinations, and substitutions are possible for those skilled in the art without departing from the scope 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 scope of the present invention. The scope of the present invention is determined by the scope of the appended claims.

Claims

1. An ultra-wide-angle lens, characterized in that: The optical system comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens, which are sequentially arranged along the optical axis from the object side to the image side; The first lens is a meniscus-shaped plastic aspheric lens or a glass spherical lens with negative optical power; the second lens is a meniscus-shaped plastic aspheric lens with negative optical power; the third lens is a biconcave plastic aspheric lens with negative optical power; the fourth lens is a biconvex glass spherical lens with positive optical power; the fifth lens is a biconvex plastic aspheric lens with positive optical power; the sixth lens is a biconcave plastic aspheric lens with negative optical power; and the seventh lens is a biconvex plastic aspheric lens with positive optical power. The image side curvature radius R2 of the first lens and the image side curvature radius R8 of the fourth lens satisfy the relationship: 0.38≤|R2 / R8|≤0.45; The F-Theta distortion of the ultra-wide-angle lens is less than -12%.

2. The ultra-wide-angle lens according to claim 1, wherein: The aperture F# of the ultra-wide-angle lens satisfies the relationship: 1.6≤F#≤2.

4.

3. The ultra-wide-angle lens according to claim 2, wherein: The focal lengths of the first to seventh lenses are f1, f2, f3, f4, f5, f6, and f7, respectively; the focal lengths of the first to seventh lenses and the ultra-wide-angle lens satisfy the following relationship: 1.05≤|f1 / f|≤2.5; 3.5≤|f2 / f|≤3.9; 3.0≤|f3 / f|≤3.67; 1.3≤|f4 / f|≤2.5; |f5 / f|≤1.98; 0.8≤|f6 / f|≤1.7; 1.45≤|f7 / f|≤1.

66.

4. The ultra-wide-angle lens according to claim 3, wherein: The refractive index n1 of the first lens is ≥1.

5.

5. The ultra-wide-angle lens according to claim 3, wherein: The focal length f3 of the third lens and the distance TTL from the front surface vertex of the first lens to the image plane satisfy the relationship: |TTL / f3|≤2.

48.

6. The ultra-wide-angle lens according to claim 3, wherein: The refractive index n4 of the fourth lens is ≥1.8, and the Abbe number V4 of the fourth lens is ≥25.

7. The ultra-wide-angle lens according to claim 3, wherein: A curvature radius R10 of the object-side surface of the fifth lens and a curvature radius R12 of the object-side surface of the sixth lens satisfy the relationship: 0.05≤|R10 / R12|≤0.

15.

8. The ultra-wide-angle lens according to claim 3, wherein: A curvature radius R15 of the image-side surface of the seventh lens element satisfies the relationship: 4.36≤|R15|≤6.

6.

9. The ultra-wide-angle lens according to claim 3, wherein: A center thickness CT6 of the sixth lens on the optical axis and a center thickness CT7 of the seventh lens on the optical axis satisfy the relationship: 0.17≤CT6 / CT7≤0.56.

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