An ultra-wide-angle lens

Abstract

An embodiment of the present invention provides an ultra-wide-angle lens, which relates to optical lens technology. The ultra-wide-angle lens includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens arranged in sequence from the object side to the image side along the optical axis. The first lens, the second lens, the fifth lens, the sixth lens and the eighth lens have negative optical power, and the third lens, the fourth lens and the seventh lens have positive optical power. An embodiment of the present invention provides an ultra-wide-angle lens, which can well correct aberrations, reduce distortion, and ensure sufficiently good image quality at a short focal length.

Description

Technical Field

[0001] The invention relates to optical lens technology, and in particular to an ultra-wide-angle lens. Background Art

[0002] Due to its large field of view, wide-angle lenses can capture a larger area of ​​scenery within a shorter shooting distance. Therefore, wide-angle lenses have been widely used in security, automotive, smart home and other fields.

[0003] With the rapid development of optical systems, the pursuit of quality for ultra-wide-angle lenses is getting higher and higher. In order to meet more measurement needs, there is a general demand for an ultra-wide-angle lens with a short total length, clear imaging and less distortion. Summary of the invention

[0004] The embodiment of the present invention provides an ultra-wide-angle lens, which can well correct aberrations, reduce distortion, and ensure sufficiently good image quality while having a short focal length.

[0005] 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, a seventh lens and an eighth lens arranged in sequence from the object side to the image side along an optical axis;

[0006] The first lens, the second lens, the fifth lens, the sixth lens and the eighth lens have negative refractive power, and the third lens, the fourth lens and the seventh lens have positive refractive power.

[0007] Optionally, the first lens is a glass spherical lens;

[0008] The second lens, the third lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are aspherical plastic lenses;

[0009] The fourth lens is a glass aspherical lens.

[0010] Optionally, the sixth lens is glued to the seventh lens;

[0011] The sixth lens is a biconcave lens, and the seventh lens is a biconvex lens.

[0012] Optionally, the refractive index of the sixth lens is Nd6, the refractive index of the seventh lens is Nd7, the Abbe number of the sixth lens is Vd6, and the Abbe number of the seventh lens is Vd7, satisfying:

[0013] 0.08≤|Nd6-Nd7|≤0.11, 20.3≤|Vd6-Vd7|≤35.

[0014] Optionally, the object side surface of the first lens is a convex surface;

[0015] The object side surface is a surface of the lens adjacent to the object side.

[0016] Optionally, the Abbe number of the first lens is Vd1, the Abbe number of the second lens is Vd2, the Abbe number of the third lens is Vd3, the Abbe number of the fourth lens is Vd4, the Abbe number of the fifth lens is Vd5, the Abbe number of the sixth lens is Vd6, the Abbe number of the seventh lens is Vd7, and the Abbe number of the eighth lens is Vd8, satisfying at least one of the following relationships:

[0017] Vd2+Vd3+Vd8≥115; Vd4+Vd5+Vd6+Vd7≤220; Vd2+Vd3+Vd4+Vd5≤220;

[0018] |Vd2-Vd5|≤20; |Vd1-Vd8|≤25.

[0019] Optionally, the center thickness of the first lens is T1, the center thickness of the third lens is T3, the center thickness of the sixth lens is T6, and the center thickness of the eighth lens is T8; at least one of the following relationships is satisfied:

[0020] (T1+T8) / T3≥0.34; (T3+T6) / T8≤7.52.

[0021] Optionally, the center thickness of the second lens is T2, the center thickness of the fourth lens is T4, the center thickness of the fifth lens is T5, the center thickness of the seventh lens is T7, the distance from the last optical surface vertex to the image plane in the ultra wide-angle lens is BFL, and half of the maximum field of view of the ultra wide-angle lens is recorded as HFOV, satisfying at least one of the following relationships:

[0022] ALT=T1+T2+T3+T4+T5+T6+T7+T8, and ALT / (T2+BFL)≥2.8;

[0023] HFOV / (T6+T7+T8)≤31.5.

[0024] Optionally, the center thickness of the first lens is T1, the center thickness of the second lens is T2, the center thickness of the fourth lens is T4, the center thickness of the fifth lens is T5, the center thickness of the seventh lens is T7, the center thickness of the eighth lens is T8, the air interval from the first lens to the center of the second lens is G12, the air interval from the second lens to the center of the third lens is G23, the air interval from the fourth lens to the center of the fifth lens is G45, the air interval from the fifth lens to the center of the sixth lens is G56, and the air interval from the seventh lens to the center of the eighth lens is G78; at least one of the following relationships is satisfied:

[0025] (T7+G78+T8) / (G45+T5+G56)≥1.6; (T1+G23) / (G12+G78)≥1.3;

[0026] G78 / (T2+T4)≤0.2; (G45+T5+G56) / T8≤2.2.

[0027] Optionally, the distance from the object side surface of the first lens to the image surface is TTL, the object side surface is the surface of the lens adjacent to the object side; the air interval from the third lens to the center of the fourth lens is G34, the air interval from the sixth lens to the center of the seventh lens is G67, the center thickness of the third lens is T3, the distance from the object side surface of the first lens to the image side surface of the eighth lens is TL, the image side surface is the surface of the lens adjacent to the image side, and the focal length of the ultra wide-angle lens is EFL;

[0028] Satisfies at least one of the following relations:

[0029] TTL / (G34+G56+G78)≤23;

[0030] AAG=G12+G23+G34+G45+G56+G67+G78, and AAG / (T3+G45)≤1.44;

[0031] TL / (G23+T3+G34+T4)≥1.766;

[0032] (G56+G78+EFL) / (T3+T5)≥0.4;

[0033] EFL / (G12+T2+G45)≥0.98.

[0034] An embodiment of the present invention provides an ultra-wide-angle lens, wherein the optical powers of the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are respectively negative, negative, positive, positive, negative, negative, negative, positive and negative. By setting the optical power of at least the first lens to the eighth lens, it is possible to correct aberrations well, reduce distortion, and ensure sufficiently good image quality at a short focal length. It can be used with a 1 / 1.8-inch chip. The first lens uses a lens with negative optical power, which can form a symmetrical optical system with the eighth lens, thereby reducing the distortion of the ultra-wide-angle lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 Schematic diagram of the structure of the ultra-wide-angle lens in Embodiment 1 of the present invention;

[0036] Figure 2 is a spherical aberration curve diagram in the first embodiment of the present invention;

[0037] Figure 3 This is a midfield curve diagram in Embodiment 1 of the present invention;

[0038] Figure 4 is a distortion curve diagram in the first embodiment of the present invention;

[0039] Figure 5 is a color difference curve diagram in the first embodiment of the present invention;

[0040] Figure 6 Schematic diagram of the structure of the ultra-wide-angle lens in Embodiment 2 of the present invention;

[0041] Figure 7 is a spherical aberration curve diagram in the second embodiment of the present invention;

[0042] Figure 8 This is a midfield curve diagram in the second embodiment of the present invention;

[0043] Fig. 9 is a distortion curve diagram in the second embodiment of the present invention;

[0044] Fig.10 is a color difference curve diagram in the second embodiment of the present invention;

[0045] Fig.11 Schematic diagram of the structure of the ultra-wide-angle lens in Embodiment 3 of the present invention;

[0046] Fig.12 is a spherical aberration curve diagram in the third embodiment of the present invention;

[0047] Fig.13 This is a midfield curve diagram in Embodiment 3 of the present invention;

[0048] Fig.14 This is a distortion curve diagram in Embodiment 3 of the present invention;

[0049] Fig.15 This is a color difference curve diagram in Embodiment 3 of the present invention;

[0050] Fig.16 Schematic diagram of the structure of the ultra-wide-angle lens in Embodiment 4 of the present invention;

[0051] Fig.17 is a spherical aberration curve diagram in the fourth embodiment of the present invention;

[0052] Fig.18 This is a field curve diagram in the fourth embodiment of the present invention;

[0053] Fig.19 is a distortion curve diagram in the fourth embodiment of the present invention;

[0054] Fig. 20 This is a color difference curve diagram in the fourth embodiment of the present invention. DETAILED DESCRIPTION

[0055] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0056] Embodiment 1

[0057] Figure 1 FIG. 1 is a schematic diagram of the structure of the ultra-wide-angle lens in the first embodiment of the present invention, with reference to FIG. Figure 1 The ultra wide-angle lens comprises a first lens 1, a second lens 2, a third lens 3, a fourth lens 4, a fifth lens 5, a sixth lens 6, a seventh lens 7 and an eighth lens 8 arranged in sequence from the object side to the image side along the optical axis. The first lens 1, the second lens 2, the fifth lens 5, the sixth lens 6 and the eighth lens 8 have negative optical power. The third lens 3, the fourth lens 4 and the seventh lens 7 have positive optical power.

[0058] The embodiment of the present invention provides an ultra-wide-angle lens, wherein the optical powers of the first lens 1, the second lens 2, the third lens 3, the fourth lens 4, the fifth lens 5, the sixth lens 6, the seventh lens 7 and the eighth lens 8 are respectively negative, negative, positive, positive, negative, negative, negative, positive and negative. By setting the optical power of at least the first lens 1 to the eighth lens 8, it is possible to correct aberrations well, reduce distortion, and ensure sufficiently good image quality at a short focal length. It can be matched with a 1 / 1.8-inch chip. The first lens 1 uses a lens with negative optical power, which can form a symmetrical optical system with the eighth lens, thereby reducing the distortion of the ultra-wide-angle lens.

[0059] Optionally, refer to Figure 1, the first lens 1 is a glass spherical lens. The second lens 2, the third lens 3, the fifth lens 5, the sixth lens 6, the seventh lens 7 and the eighth lens 8 are aspherical plastic lenses. The fourth lens 4 is a glass aspherical lens. This embodiment adopts the 1G1GM6P combination, which can well correct aberrations, reduce distortion, and ensure sufficiently good image quality at a short focal length.

[0060] Optionally, refer to Figure 1 , the sixth lens 6 is glued with the seventh lens 7, and the sixth lens 6 and the seventh lens 7 form a double glued lens. The sixth lens 6 is a double concave lens, and the seventh lens 7 is a double convex lens. Among them, the object side surface and the image side surface of the double concave lens are both concave surfaces, and the object side surface and the image side surface of the double convex lens are both convex surfaces. The object side surface is the surface of the lens adjacent to the object side, and the image side surface is the surface of the lens adjacent to the image side. The sixth lens 6 and the seventh lens 7 form a double glued lens, which can better correct the chromatic aberration of the ultra-wide-angle lens and improve the imaging quality on the one hand; on the other hand, it can better reduce the volume of the ultra-wide-angle lens and make the ultra-wide-angle lens miniaturized.

[0061] Optionally, refer to Figure 1 , the refractive index of the sixth lens 6 is Nd6, and the refractive index of the seventh lens 7 is Nd7. The Abbe number of the sixth lens 6 is Vd6, and the Abbe number of the seventh lens 7 is Vd7, which satisfies: 0.08≤|Nd6-Nd7|≤0.11, 20.3≤|Vd6-Vd7|≤35. The chromatic aberration of the ultra-wide-angle lens can be corrected well to improve the imaging quality.

[0062] Optionally, refer to Figure 1 , the object side of the first lens 1 is convex. Therefore, the object side of the first lens 1 plays a role in converging light, so that light with a larger field of view angle can enter the imaging system, so that the ultra-wide-angle lens meets the requirements of a large field of view. As an example, the first lens 1 is a meniscus structure, that is, the first lens 1 is a convex-concave lens, and the image side of the first lens 1 is a concave surface.

[0063] Optionally, refer to Figure 1 , the distance from the object side surface of the first lens 1 to the image plane is TTL, TTL≤18. Further, 17.26≤TTL≤18.

[0064] Optionally, refer to Figure 1 , the Abbe number of the first lens 1 is Vd1, the Abbe number of the second lens 2 is Vd2, the Abbe number of the third lens 3 is Vd3, the Abbe number of the fourth lens 4 is Vd4, the Abbe number of the fifth lens 5 is Vd5, the Abbe number of the sixth lens 6 is Vd6, the Abbe number of the seventh lens 7 is Vd7, and the Abbe number of the eighth lens 8 is Vd8. Vd2+Vd3+Vd8≥115. Further, 117.17≤Vd2+Vd3+Vd8≤135.34.

[0065] Optionally, AAG=G12+G23+G34+G45+G56+G67+G78, the distance from the last optical surface vertex to the image plane in the ultra-wide-angle lens is BFL, and AAG / BFL≥2. Further, 2≤AAG / BFL≤3.19.

[0066] Optionally, refer to Figure 1 , the center thickness of the first lens 1 is T1, the center thickness of the second lens 2 is T2, the center thickness of the third lens 3 is T3, the center thickness of the fourth lens 4 is T4, the center thickness of the fifth lens 5 is T5, the center thickness of the sixth lens 6 is T6, the center thickness of the seventh lens 7 is T7, the center thickness of the eighth lens 8 is T8, (T1+T8) / T3≥0.34. Further, 0.34≤(T1+T8) / T3≤0.47.

[0067] Optionally, half of the diagonal length of the effective pixel area on the image plane is ImgH, and Fno is the F number, also known as the aperture number. Fno can be recorded as F / #. ImgH / Fno≥2.59. Further, 2.6≤ImgH / Fno≤2.77.

[0068] Optionally, the focal length of the ultra-wide-angle lens is EFL, the distance from the last optical surface vertex in the ultra-wide-angle lens to the image plane is BFL, (EFL+BFL) / Fno≥2.5. Further, 2.5≤(EFL+BFL) / Fno≤3.27.

[0069] Optionally, ImGH / BFL≥1.93. Further, 1.94≤ImGH / BFL≤2.68.

[0070] Optionally, ALT = T1 + T2 + T3 + T4 + T5 + T6 + T7 + T8. ALT / (T2 + BFL) ≥ 2.8. Further, 2.8 ≤ ALT / (T2 + BFL) ≤ 5.21.

[0071] Optionally, (G56+G78+EFL) / (T3+T5)≥0.4. Further, 0.4≤(G56+G78+EFL) / (T3+T5)≤0.88.

[0072] Optionally, refer to Figure 1 , the distance from the object side surface of the first lens 1 to the image side surface of the eighth lens 8 is TL, TL / (G23+T3+G34+T4)≥1.766. Further, 1.75≤TL / (G23+T3+G34+T4)≤2.07.

[0073] Optionally, (T7+G78+T8) / (G45+T5+G56)≥1.6. Further, 1.6≤(T7+G78+T8) / (G45+T5+G56)≤2.69.

[0074] Optionally, EFL / (G12+T2+G45)≥0.98. Further, 0.98≤EFL / (G12+T2+G45)≤1.35.

[0075] Optionally, (T1+G23) / (G12+G78)≥1.3. Further, 1.3≤(T1+G23) / (G12+G78)≤3.09.

[0076] Optionally, G78 / (T2+T4)≤0.2. Further, 0.15≤G78 / (T2+T4)≤0.2.

[0077] Optionally, Vd4+Vd5+Vd6+Vd7≤220. Further, 185.93≤Vd4+Vd5+Vd6+Vd7≤217.43.

[0078] Optionally, Vd2+Vd3+Vd4+Vd5≤220. Further, 198.78≤Vd2+Vd3+Vd4+Vd5≤216.71.

[0079] Optionally, |Vd2-Vd5|≤20, |Vd1-Vd8|≤25.

[0080] Optionally, ALT=T1+T2+T3+T4+T5+T6+T7+T8. ALT / (T1+G12)≤5.7. Further, 4.7≤ALT / (T1+G12)≤5.7.

[0081] Optionally, refer to Figure 1 , the distance from the object side surface of the first lens 1 to the image side surface of the eighth lens 8 is TL, TL / (G23+G34+T4)≤5. 3.14≤TL / (G23+G34+T4)≤5.

[0082] Optionally, ALT = T1 + T2 + T3 + T4 + T5 + T6 + T7 + T8. ALT / (G23 + G78) ≤ 6.42. Further, 3.02 ≤ ALT / (G23 + G78) ≤ 6.42.

[0083] Optionally, (G45+T5+G56) / T8≤2.2. Further, 1.54≤(G45+T5+G56) / T8≤2.2.

[0084] Optionally, half of the maximum field of view of the ultra-wide-angle lens is recorded as HFOV, and HFOV / (T6+T7+T8)≤31.5. Further, 22.89≤HFOV / (T6+T7+T8)≤31.5.

[0085] Optionally, refer to Figure 1 , the distance from the object side surface of the first lens 1 to the image plane is TTL, HFOV / TTL≤4.58. Further, 4.39≤HFOV / TTL≤4.58.

[0086] Optionally, TTL / (G34+G56+G78)≤23. Further, 12.18≤TTL / (G34+G56+G78)≤22.97.

[0087] Optionally, (T3+T6) / T8≤7.52. Further, 5.48≤(T3+T6) / T8≤7.52.

[0088] Optionally, AAG=G12+G23+G34+G45+G56+G67+G78, AAG / (T3+G45)≤1.44. Further, 0.77≤AAG / (T3+G45)≤1.44.

[0089] Optionally, refer to Figure 1 The ultra-wide-angle lens further includes a stop STO and a filter 9. The stop STO is located between the third lens 3 and the fourth lens 4. The filter 9 is located on the side of the eighth lens 8 away from the first lens 1, and the filter 9 is located between the eighth lens 8 and the image plane IMA. The material of the filter 9 can be H-K9L.

[0090] Table 1 A design value of the ultra-wide-angle lens in Example 1

[0091]

[0092]

[0093] Table 1 shows a design value of the ultra-wide-angle lens in Example 1, and its specific value can be adjusted according to product requirements and is not a limitation of the embodiment of the present invention. The ultra-wide-angle lens shown in Table 1 can be Figure 1As shown in . A lens generally includes two surfaces, each of which is a refractive surface. The surface numbers in Table 1 are numbered according to the surfaces of each lens. Among them, the surface number "S1" represents the front surface of the first lens 1 (i.e., the object side), the surface number "S2" represents the back surface of the first lens 1 (i.e., the image side), and so on, which will not be repeated here. It should be noted that "STO" in the "Surface Number" column represents the plane where the aperture is located. "IMA" in the "Surface Number" column represents the image plane. The radius of curvature represents the degree of curvature of the lens surface. A positive radius of curvature value indicates that the center of curvature is on the side of the surface close to the image side, that is, a positive value represents that the surface is bent toward the image plane IMA side; a negative radius of curvature value represents that the center of curvature is on the side of the surface away from the image side, that is, a negative value represents that the surface is bent toward the object plane (i.e., the object side). "INF" in the "Radius of Curvature" column represents that the surface is a plane and the radius of curvature is infinite. The value in the "Thickness" column represents the central axial distance from the current surface to the next surface. The "Refractive Index" column indicates the refractive index of the medium between the current surface and the next surface, representing the ability of the material between the current surface and the next surface to deflect light. The blank in the "Refractive Index" column is the refractive index of air, which is 1. The Abbe number represents the dispersion characteristics of the material between the current surface and the next surface to light, and the blank represents that the current position is air. The value in the "Half-Aperture" column represents half of the aperture of the current surface.

[0094] Optionally, the surface of the aspheric lens satisfies the formula:

[0095]

[0096] Among them, z is the axial vector height of the surface in the Z direction, r is the height of the aspheric surface, that is, z is the distance vector height from the vertex of the aspheric surface when the aspheric surface is at a height of r along the optical axis; c is the curvature of the fitted sphere, numerically c is the inverse of the radius of curvature, c = 1 / R, R represents the paraxial curvature radius of the mirror; k is the cone coefficient, A, B, C, D, E, F, G, H, I are the aspheric coefficients, specifically, A, B, C, D, E, F, G, H, I are the 4th, 6th, 8th, 10th, 12th, 14th, 16th, 18th and 20th order coefficients of the aspheric polynomial, respectively.

[0097] Table 2 A design value of the aspheric coefficient of the lens in the ultra-wide-angle lens in Example 1

[0098]

[0099]

[0100] Table 2 shows a design value of the aspheric coefficient of the lens in the ultra-wide-angle lens of Example 1. The specific value can be adjusted according to product requirements and is not a limitation of the embodiment of the present invention. The ultra-wide-angle lens shown in Table 2 can be Figure 1 The meaning of the column "surface number" in Table 2 is consistent with that of the column "surface number" in Table 1. "E" in each embodiment of the present invention represents an index with base 10.

[0101] For example, in the first embodiment, the focal length of the ultra-wide-angle lens is 3.012 mm, the F / # (i.e., the aperture number) is 1.8, the total length is 18 mm, and the optimal working object distance is infinity.

[0102] Figure 2 is a spherical aberration curve diagram in the first embodiment of the present invention, referring to Figure 2 , the vertical direction represents the normalization of the aperture, 0 represents the optical axis, the vertical vertex represents the maximum pupil radius; the horizontal direction represents the offset relative to the ideal focus, in millimeters (mm). The different linear curves in the figure represent different wavelengths of system imaging, which are represented by Figure 5 It can be seen that the axial aberrations at different wavelengths are all controlled within the range of (-0.2mm, +0.2mm), indicating that the spherical aberration of the ultra-wide-angle lens at each wavelength is well controlled and can meet the needs of wide spectrum applications.

[0103] Figure 3 This is a midfield curve diagram in the first embodiment of the present invention, refer to Figure 3 , the horizontal coordinate represents the magnitude of the field curvature, in mm; the vertical coordinate represents the normalized image height, without units. Where T represents the meridian, and S represents the arc loss. Figure 3 It can be seen that the field curvature of light of each wavelength is effectively controlled, that is, when imaging, the difference between the image quality in the center and the periphery is small.

[0104] Figure 4 is a distortion curve diagram in the first embodiment of the present invention, referring to Figure 4 The horizontal coordinate represents the size of the distortion, and the unit is percentage, i.e. %. The vertical coordinate represents the normalized image height, and has no unit.

[0105] Figure 5 is a color difference curve diagram in the first embodiment of the present invention, referring to Figure 5 , the vertical direction represents the image height, in mm; the horizontal direction represents the offset of different wavelengths from the optical axis at the image plane after passing through the system, in micrometers (μm). The different linear curves in the figure represent different wavelengths of imaging by the system; the curves on both sides of the figure in the vertical direction are Airy disks.

[0106] Embodiment 2

[0107] The same points as those in the first embodiment are not repeated here.

[0108] Table 3 A design value of the ultra-wide-angle lens in Example 2

[0109]

[0110]

[0111] Table 3 shows a design value of the ultra-wide-angle lens in Example 2, and its specific value can be adjusted according to product requirements and is not a limitation of the embodiment of the present invention. The ultra-wide-angle lens shown in Table 3 can be Figure 6 as shown in .

[0112] Table 4 A design value of the aspheric coefficient of the lens in the ultra-wide-angle lens in Example 2

[0113]

[0114]

[0115] Table 4 shows a design value of the aspheric coefficient of the lens in the ultra-wide-angle lens of Example 2. The specific value can be adjusted according to product requirements and is not a limitation of the embodiment of the present invention. The ultra-wide-angle lens shown in Table 4 can be Figure 6 as shown in .

[0116] For example, in the second embodiment, the focal length of the ultra-wide-angle lens is 2.355, the F / # (i.e., the aperture number) is 1.8, the total length is 17.3 mm, and the optimal working object distance is infinity.

[0117] Embodiment 3

[0118] The same points as those in the first embodiment are not repeated here.

[0119] Table 5: Design values ​​of the ultra-wide-angle lens in Example 3

[0120]

[0121]

[0122] Table 5 shows a design value of the ultra-wide-angle lens in Example 3, and its specific value can be adjusted according to product requirements and is not a limitation of the embodiment of the present invention. The ultra-wide-angle lens shown in Table 5 can be Fig.11 as shown in .

[0123] Table 6 A design value of the aspheric coefficient of the lens in the ultra-wide-angle lens in Example 3

[0124]

[0125]

[0126] Table 6 shows a design value of the aspheric coefficient of the lens in the ultra-wide-angle lens of Example 3. The specific value can be adjusted according to product requirements and is not a limitation of the embodiment of the present invention. The ultra-wide-angle lens shown in Table 6 can be Fig.11 as shown in .

[0127] For example, in the third embodiment, the focal length of the ultra-wide-angle lens is 2.187, the F / # (i.e., the aperture number) is 1.8, the total length is 17.9 mm, and the optimal working object distance is infinity.

[0128] Embodiment 4

[0129] The same points as those in the first embodiment are not repeated here.

[0130] Table 7 A design value of the ultra-wide-angle lens in Example 4

[0131]

[0132]

[0133] Table 7 shows a design value of the ultra-wide-angle lens in the fourth embodiment, and its specific value can be adjusted according to product requirements and is not a limitation of the embodiment of the present invention. The ultra-wide-angle lens shown in Table 7 can be Fig.16 as shown in .

[0134] Table 8 A design value of the aspheric coefficient of the lens in the ultra-wide-angle lens in Example 4

[0135]

[0136]

[0137] Table 8 is a design value of the aspheric coefficient of the lens in the ultra-wide-angle lens of Example 4. The specific value can be adjusted according to product requirements and is not a limitation of the embodiment of the present invention. The ultra-wide-angle lens shown in Table 8 can be Fig.16 as shown in .

[0138] For example, in the fourth embodiment, the focal length of the ultra-wide-angle lens is 2.718, the F / # (i.e., the aperture number) is 1.8, the total length is 17.9 mm, and the optimal working object distance is infinity.

[0139] Note that the above are only preferred embodiments of the present invention and the technical principles used. 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, combinations 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 more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and 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: It includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens and an eighth lens which are arranged in sequence from the object side to the image side along the optical axis; The first lens, the second lens, the fifth lens, the sixth lens and the eighth lens have negative optical power, and the third lens, the fourth lens and the seventh lens have positive optical power; The second lens, the third lens, the fifth lens, the sixth lens, the seventh lens and the eighth lens are aspherical plastic lenses; The sixth lens is glued to the seventh lens; the sixth lens is a biconcave lens, and the seventh lens is a biconvex lens; The refractive index of the sixth lens is Nd6, the refractive index of the seventh lens is Nd7, the Abbe number of the sixth lens is Vd6, and the Abbe number of the seventh lens is Vd7, which satisfies: 0.08≤|Nd6-Nd7|≤0.11, 20.3≤|Vd6-Vd7|≤35.

2. The ultra-wide-angle lens according to claim 1, characterized in that: The first lens is a glass spherical lens; The fourth lens is a glass aspherical lens.

3. The ultra-wide-angle lens according to claim 1, characterized in that: The object side surface of the first lens is a convex surface; The object side surface is a surface of the lens adjacent to the object side.

4. The ultra-wide-angle lens according to claim 1, characterized in that: The Abbe number of the first lens is Vd1, the Abbe number of the second lens is Vd2, the Abbe number of the third lens is Vd3, the Abbe number of the fourth lens is Vd4, the Abbe number of the fifth lens is Vd5, and the Abbe number of the eighth lens is Vd8, which satisfies at least one of the following relationships: Vd2+Vd3+Vd8≥115; Vd4+Vd5+Vd6+Vd7≤220; Vd2+Vd3+ Vd4+Vd5≤220; |Vd2- Vd5|≤20; |Vd1- Vd8|≤25.

5. The ultra-wide-angle lens according to claim 1, characterized in that: The center thickness of the first lens is T1, the center thickness of the third lens is T3, the center thickness of the sixth lens is T6, and the center thickness of the eighth lens is T8; at least one of the following relationships is satisfied: (T1+T8) / T3≥0.34; (T3+T6) / T8≤7.

52.

6. The ultra-wide-angle lens according to claim 5, characterized in that: The center thickness of the second lens is T2, the center thickness of the fourth lens is T4, the center thickness of the fifth lens is T5, the center thickness of the seventh lens is T7, the distance from the last optical surface vertex to the image plane in the ultra-wide-angle lens is BFL, and half of the maximum field of view of the ultra-wide-angle lens is recorded as HFOV, satisfying at least one of the following relationships: ALT=T1+T2+T3+T4+T5+T6+T7+T8, and ALT / (T2+BFL)≥2.8; HFOV / (T6+T7+T8) ≤31.

5.

7. The ultra-wide-angle lens according to claim 1, characterized in that: The center thickness of the first lens is T1, the center thickness of the second lens is T2, the center thickness of the fourth lens is T4, the center thickness of the fifth lens is T5, the center thickness of the seventh lens is T7, the center thickness of the eighth lens is T8, the air interval from the first lens to the center of the second lens is G12, the air interval from the second lens to the center of the third lens is G23, the air interval from the fourth lens to the center of the fifth lens is G45, the air interval from the fifth lens to the center of the sixth lens is G56, and the air interval from the seventh lens to the center of the eighth lens is G78; at least one of the following relationships is satisfied: (T7+G78+T8) / (G45+T5+G56) ≥1.6; (T1+G23) / (G12+G78) ≥1.3; G78 / (T2+T4) ≤0.2; (G45+T5+G56) / T8≤2.

2.

8. The ultra-wide-angle lens according to claim 7, characterized in that: The distance from the object side surface of the first lens to the image surface is TTL, and the object side surface is the surface of the lens adjacent to the object side; the air interval from the third lens to the center of the fourth lens is G34, the air interval from the sixth lens to the center of the seventh lens is G67, the center thickness of the third lens is T3, the distance from the object side surface of the first lens to the image side surface of the eighth lens is TL, and the image side surface is the surface of the lens adjacent to the image side, and the focal length of the ultra wide-angle lens is EFL; Satisfies at least one of the following relations: TTL / (G34+G56+G78) ≤23; AAG=G12+ G23+ G34+ G45+ G56+ G67+ G78, and AAG / (T3+G45) ≤1.44; TL / (G23+T3+G34+T4) ≥1.766; (G56+G78+EFL) / (T3+T5) ≥0.4; EFL / (G12+T2+G45) ≥0.98.

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