Imaging lens

Abstract

The present invention relates to an imaging lens, which comprises, in order from the object side to the image side of the optical axis: a first lens group (G1) comprising at least four lenses, an aperture (STO), and a second lens group (G2) comprising at least four lenses. The image side surface of the lens closest to the aperture side of the first lens group (G1) is convex; the optical power of the lens closest to the aperture side of the second lens group (G2) is negative, and the object side surface is concave; the first lens group (G1) and the second lens group (G2) are relatively stationary. The imaging lens has the characteristics of low distortion, high pixel count, large target surface, large aperture, high relative illumination, and good assembly tolerance. The absolute value of distortion is less than 25%, the image resolution can reach 12 million pixels, the full image height can reach 18 mm, the FNO is ≤ 1.8, and the relative illumination is above 45%.

Description

Technical Field

[0001] The present invention relates to the technical field of optical imaging systems, and in particular to an imaging lens. Background Art

[0002] With the development of intelligent transportation systems, the market requirements for intelligent transportation lenses are becoming increasingly stringent. Existing intelligent transportation lenses on the market struggle to balance image quality and relative illumination while meeting the requirements of large aperture and large target area. This limits the lens's operating environment and makes it difficult to control optical distortion during design.

[0003] Chinese patent CN214225554U discloses an imaging lens, which comprises a first lens group, an aperture, and a second lens group as a focusing group arranged in sequence from the object side to the image side. This lens has good imaging performance and good high and low temperature performance, but does not address the issue of balancing high pixels, relative illumination, and low distortion. Summary of the Invention

[0004] To overcome the above-mentioned defects in the prior art, the object of the present invention is to provide an imaging lens that can achieve 12 million high pixels, relative illumination and low distortion, with the absolute value of distortion being less than 25%.

[0005] To achieve the above-mentioned objectives, the present invention provides an imaging lens comprising, in order from the object side to the image side of the optical axis, a first lens group comprising at least four lenses, an aperture, and a second lens group comprising at least four lenses, wherein the image-side surface of the lens closest to the aperture in the first lens group is convex; the optical power of the lens closest to the aperture in the second lens group is negative, and the object-side surface is concave; and the first lens group and the second lens group are relatively stationary.

[0006] According to one aspect of the present invention, the first lens group includes at least one biconcave lens and at least one biconvex lens.

[0007] According to one aspect of the present invention, the first lens group includes at least two lenses with negative optical power and at least two lenses with positive optical power.

[0008] According to one aspect of the present invention, the second lens group includes at least one biconcave lens and at least two biconvex lenses.

[0009] According to one aspect of the present invention, the second lens group includes at least one lens with negative optical power and at least three lenses with positive optical power.

[0010] According to one aspect of the present invention, all lenses in the imaging lens are spherical lenses.

[0011] According to one aspect of the present invention, the imaging lens comprises at least two cemented lenses.

[0012] According to one aspect of the present invention, the second lens group includes at least one doublet lens.

[0013] According to one aspect of the present invention, the focal length Fa of the doublet lens and the focal length F2 of the second lens group satisfy the relationship: -29.67≤Fa / F2≤11.89.

[0014] According to one aspect of the present invention, the focal length F1 of the first lens group and the focal length F2 of the second lens group satisfy the relationship: -78.90≤F1 / F2≤11.36.

[0015] According to one aspect of the present invention, the focal length F1 of the first lens group and the focal length F of the imaging lens satisfy the relationship: -163.11≤F1 / F≤27.50.

[0016] According to one aspect of the present invention, the refractive index Nd of at least two lenses included in the imaging lens satisfies the relationship: Nd≥1.8.

[0017] According to one aspect of the present invention, the Abbe numbers Vd of the at least four lenses included in the imaging lens satisfy the relationship: Vd≤45.

[0018] According to the solution of the present invention, an imaging lens is provided, having a large target area, a full image height of up to 18mm, a large aperture FNO ≤ 1.8, clear virtual and real image quality, good background blur quality, and a relative illumination of 45% or more. By adopting the optical structure of a first lens group and a second lens group, and by rationally arranging the positive and negative optical power lenses in the first and second lens groups and combining the shapes of the concave and convex lenses, 12-megapixel high-pixel imaging is achieved while correcting lens aberrations and reducing the tolerance sensitivity of the optical imaging system. The lens also has the excellent characteristic of low distortion, with an absolute distortion value of less than 25%.

[0019] According to one embodiment of the present invention, by using a doublet or triplet lens and rationally setting the positive and negative optical power and optical power size of the doublet lens, other lenses and the entire optical imaging system, the aberration and chromatic aberration of the imaging lens can be corrected, the imaging resolution can be improved, and the assembly tolerance can be small.

[0020] According to one aspect of the present invention, by combining spherical lenses with different refractive and scattering properties, appropriately arranging low-abbe coefficient lenses, and combining them with different lens shapes, it is possible to reduce spherical lens aberrations and chromatic aberrations, thereby improving image clarity and color saturation. The use of materials with widely varying Abbe numbers effectively corrects axial chromatic aberration in the entire optical imaging system. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 A schematic diagram schematically illustrates the optical structure of an imaging lens according to a first embodiment of the present invention;

[0022] Figure 2 A schematic diagram schematically illustrates the optical structure of an imaging lens according to a second embodiment of the present invention;

[0023] Figure 3 A schematic diagram schematically illustrates the optical structure of an imaging lens according to a third embodiment of the present invention;

[0024] Figure 4 A schematic diagram schematically illustrates the optical structure of an imaging lens according to a fourth embodiment of the present invention;

[0025] Figure 5 The figure schematically shows the optical structure of the imaging lens according to the fifth embodiment of the present invention. DETAILED DESCRIPTION

[0026] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be derived from these drawings without inventive effort.

[0027] When describing the embodiments of the present invention, the orientation or positional relationship expressed by the terms "longitudinal", "transverse", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" are based on the orientation or positional relationship shown in the relevant drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the above terms should not be understood as limiting the present invention.

[0028] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described one by one here, but the embodiments of the present invention are not limited to the following embodiments.

[0029] See also Figure 1, along the optical axis from the object side to the image side, the imaging lens of the present invention comprises, in sequence: a first lens group G1, an aperture STO, and a second lens group G2. The first lens group and the second lens group each contain at least four lenses. The image-side surface of the lens closest to the aperture in the first lens group is convex, while the optical power of the lens closest to the aperture in the second lens group is negative and the object-side surface is concave. The first lens group and the second lens group are relatively stationary. When the object distance of the imaging lens changes, the optical system performs overall focusing. That is, the first lens group and the second lens group simultaneously move along the optical axis to achieve focusing, while also compensating for and correcting aberrations, enabling large-surface, 12-megapixel high-pixel imaging.

[0030] The first lens group of this lens includes at least one biconcave lens and at least one biconvex lens. Furthermore, the first lens group includes at least two lenses with negative optical power and at least two lenses with positive optical power. This structure, by employing a combination of multiple positive and negative lenses, facilitates achieving low distortion in the first lens group of this lens. Furthermore, the combination of multiple concave and convex lenses facilitates correcting aberrations in the first lens group of this lens, reducing the tolerance sensitivity of the optical imaging system and achieving high-pixel imaging, a large aperture, and a relative illumination of over 45%.

[0031] The second lens group of this lens includes at least one biconcave lens and at least two biconvex lenses. Furthermore, the second lens group includes at least one lens with negative optical power and at least three lenses with positive optical power. This structure, by employing a combination of multiple positive and negative lenses, facilitates achieving low distortion characteristics in the second lens group of this lens. The combination of multiple concave and convex lenses also facilitates correcting aberrations in the second lens group of this lens, reducing the tolerance sensitivity of the optical imaging system and achieving high-pixel imaging, a large aperture, and a relative illumination of over 45%.

[0032] All lenses in this imaging lens are spherical lenses, which are low-cost. The combination of the above-mentioned lens combinations with different concave and convex shapes can effectively offset the imaging aberration of the lens, improve the imaging quality of the spherical lenses, and achieve 12-megapixel performance.

[0033] The imaging lens comprises at least two cemented lenses. The cemented lenses can be double cemented lenses or triple cemented lenses. The second lens group comprises at least one double cemented lens. Figure 1 As shown in the figure, the first lens group of the lens includes a triplet lens, and the second lens group includes a doublet lens. Figure 2 As shown in the figure, the first lens group of the lens contains a triplet lens, and the second lens group contains two doublet lenses. Figure 3 As shown in the figure, the first lens group of the lens includes a doublet lens, and the second lens group includes two doublet lenses. Figure 4As shown, the first lens group and the second lens group of the lens each contain a doublet lens. Figure 5 As shown, the first lens group of this lens comprises a triplet, and the second lens group comprises two doublets. The use of cemented lenses in this lens helps correct aberrations and chromatic aberrations in the first and second lens groups, further reducing the tolerance sensitivity of the optical imaging system and improving the imaging quality of the optical system.

[0034] Furthermore, the focal length Fa of the doublet lens and the focal length F2 of the second lens group satisfy the relationship: -29.67 ≤ Fa / F2 ≤ 11.89. By adjusting the positive and negative focal powers, as well as the focal power levels, of the doublet lens in the second lens group and the second lens group, chromatic aberration can be effectively corrected, image resolution can be improved, and assembly tolerances and yield rates can be increased.

[0035] The focal length F1 of the first lens group and the focal length F2 of the second lens group satisfy the relationship: -78.90 ≤ F1 / F2 ≤ 11.36. The focal length F1 of the first lens group and the focal length F of the imaging lens satisfy the relationship: -163.11 ≤ F1 / F ≤ 27.50. Therefore, by rationally combining the positive and negative focal powers and their magnitudes among the first and second lens groups and the entire optical imaging system, and by appropriately adjusting the focal powers of all three, focus degradation at varying object distances can be avoided, system tolerance sensitivity can be easily reduced, and imaging quality can be improved.

[0036] The refractive index Nd of at least two lenses in the imaging lens satisfies the relationship: Nd ≥ 1.8. The Abbe number Vd of at least four lenses in the imaging lens satisfies the relationship: Vd ≤ 45. By combining spherical lenses with different refractive and scattering properties, and by strategically placing lenses with low dispersion characteristics, this lens can reduce chromatic aberration and improve image clarity and color saturation. The use of materials with widely varying Abbe numbers effectively corrects axial chromatic aberration of the entire optical imaging system.

[0037] In summary, the imaging lens of the present invention features low distortion, with an absolute distortion value of less than 25%, and image quality reaching 12 megapixels. It also boasts a large image area, with a full image height of up to 18mm, a large aperture (FNO) ≤ 1.8, and clear visual and real image quality, with excellent background blur. The lens also boasts high relative illumination (RI) exceeding 45%, tight assembly tolerances, and a high assembly yield.

[0038] The following five embodiments specifically illustrate the imaging lens of the present invention. In each of the following embodiments, the imaging lens of the present invention comprises a lens, an aperture stop STO, a prism SG, and an image-side surface IMA. The aperture stop STO is referred to as one surface STO, the image-side surface IMA is referred to as one surface IMA, the cemented surface of a doublet is referred to as one surface, and the cemented surface of a triplet is referred to as two surfaces. Each lens and prism SG in the lens has two surfaces.

[0039] Parameters of various embodiments that specifically meet the above conditional formula are shown in Table 1 below:

[0040]

[0041] Table 1

[0042] Example 1

[0043] See also Figure 1 In this embodiment, the first lens group includes a total of seven lenses, including one biconcave lens and two biconvex lenses, four lenses with negative optical power and three lenses with positive optical power. The second lens group includes a total of four lenses, including one biconcave lens and three biconvex lenses, one lens with negative optical power and three lenses with positive optical power.

[0044] The first lens group includes a triplet lens, and the second lens group includes a doublet lens. The fifth, sixth, and seventh lenses are cemented together to form a triplet lens, and the eighth and ninth lenses are cemented together to form a doublet lens.

[0045] The parameters of each lens of the imaging lens of this embodiment include the surface type, curvature radius R, thickness d, refractive index Nd of the material, and Abbe number Vd. S1 to S22 represent the surfaces of each lens, cemented lens, aperture STO, and prism SG in the imaging lens, as shown in Table 2 below:

[0046] Surface number Surface type Curvature radius R Thickness d Refractive index Nd Abbe number Vd 1 spherical surface Infinity 0.9 1.75 52.3 2 spherical surface 17.7 6.6 3 spherical surface -19.2 0.9 1.50 81.6 4 spherical surface 43.6 6.8 5 spherical surface -46.9 3.2 1.72 29.5 6 spherical surface -24.6 0.1 7 spherical surface 30.4 4.4 1.69 31.2 8 spherical surface -146.5 17.8 9 spherical surface 65.4 0.9 1.95 18.0 10 spherical surface 26.4 6.1 1.52 64.2 11 spherical surface -15.8 0.9 1.91 35.3 12 spherical surface -30.7 2 STO spherical surface Infinity 3.6 14 spherical surface -28.9 0.9 1.75 25.0 15 spherical surface 39.7 4.4 1.44 95.1 16 spherical surface -29.5 0.1 17 spherical surface 66.1 4.6 1.50 81.6 18 spherical surface -33.2 0.1 19 spherical surface 64.0 2.9 1.95 18.0 20 spherical surface -156.5 0.1 21 spherical surface Infinity 21 1.52 64.2 22 spherical surface Infinity 16.888 Image spherical surface Infinity -

[0047] Table 2

[0048] Combine Figure 1 As can be seen from the data in Tables 1 and 2, the imaging lens of this embodiment exhibits low distortion, with an absolute distortion value of less than 25%, and image quality reaching 12 megapixels. It also features a large image area, with a full image height of up to 18mm and a large aperture FNO ≤ 1.8. The lens also boasts high relative illumination, exceeding 45%, tight assembly tolerances, and a high assembly yield.

[0049] Example 2

[0050] See also Figure 2In this embodiment, the first lens group includes eight lenses, including three biconcave lenses and two biconvex lenses, five lenses with negative optical power and three lenses with positive optical power. The second lens group includes five lenses, including one biconcave lens and three biconvex lenses, two lenses with negative optical power and three lenses with positive optical power.

[0051] The first lens group includes a triplet lens, and the second lens group includes two doublet lenses. Among them, the sixth lens, the seventh lens, and the eighth lens are cemented to form a triplet lens, the ninth lens and the tenth lens are cemented to form a doublet lens, and the eleventh lens and the twelfth lens are cemented to form a doublet lens.

[0052] The parameters of each lens of the imaging lens of this embodiment include the surface type, curvature radius R, thickness d, refractive index Nd of the material, and Abbe number Vd. S1 to S25 represent the surfaces of each lens, cemented lens, aperture STO, and prism SG in the imaging lens, as shown in Table 3 below:

[0053]

[0054]

[0055] Table 3

[0056] Combine Figure 2 As can be seen from the data in Tables 1 and 3, the imaging lens of this embodiment exhibits low distortion, with an absolute distortion value of less than 25%, and image quality reaching 12 megapixels. It also features a large image area, with a full image height of up to 18mm and a large aperture (FNO) of ≤1.8. The lens also boasts high relative illumination (RI) exceeding 45%, tight assembly tolerances, and a high assembly yield.

[0057] Example 3

[0058] See also Figure 3 In this embodiment, the first lens group includes four lenses, including one biconcave lens and two biconvex lenses, including two lenses with negative optical power and two lenses with positive optical power. The second lens group includes six lenses, including one biconcave lens and four biconvex lenses, including two lenses with negative optical power and four lenses with positive optical power.

[0059] The first lens group includes a doublet lens, and the second lens group includes two doublet lenses. The second lens and the third lens are cemented to form a doublet lens, the fifth lens and the sixth lens are cemented to form a doublet lens, and the eighth lens and the ninth lens are cemented to form a doublet lens.

[0060] The parameters of each lens of the imaging lens of this embodiment include the surface type, curvature radius R, thickness d, refractive index Nd of the material, and Abbe number Vd. S1 to S20 represent the surfaces of each lens, cemented lens, aperture STO, and prism SG in the imaging lens, as shown in Table 4 below:

[0061]

[0062]

[0063] Table 4

[0064] Combine Figure 3 As can be seen from the data in Tables 1 and 4, the imaging lens of this embodiment exhibits low distortion, with an absolute distortion value of less than 25%, and image quality reaching 12 megapixels. It also features a large image area, with a full image height of up to 18mm and a large aperture (FNO) of ≤1.8. The lens also exhibits high relative illumination, exceeding 45%, tight assembly tolerances, and a high assembly yield.

[0065] Example 4

[0066] See also Figure 4 In this embodiment, the first lens group includes a total of seven lenses, including one biconcave lens and one biconvex lens, four lenses with negative optical power, and three lenses with positive optical power. The second lens group includes a total of four lenses, including one biconcave lens and two biconvex lenses, one lens with negative optical power, and three lenses with positive optical power.

[0067] The first lens group and the second lens group each include a doublet lens, wherein the sixth lens and the seventh lens are cemented to form a doublet lens, and the eighth lens and the ninth lens are cemented to form a doublet lens.

[0068] The parameters of each lens of the imaging lens of this embodiment include the surface type, curvature radius R, thickness d, refractive index Nd of the material, and Abbe number Vd. S1 to S23 represent the surfaces of each lens, cemented lens, aperture STO, and prism SG in the imaging lens, as shown in Table 5 below:

[0069]

[0070]

[0071] Table 5

[0072] Combine Figure 4As can be seen from the data in Tables 1 and 5, the imaging lens of this embodiment exhibits low distortion, with an absolute distortion value of less than 25%, and image quality reaching 12 megapixels. It also features a large image area, with a full image height of up to 18mm and a large aperture (FNO) of ≤1.8. The lens also exhibits high relative illumination, exceeding 45%, tight assembly tolerances, and a high assembly yield.

[0073] Example 5

[0074] See also Figure 5 In this embodiment, the first lens group includes eight lenses, including two biconcave lenses and two biconvex lenses, five lenses with negative optical power and three lenses with positive optical power. The second lens group includes six lenses, including one biconcave lens and four biconvex lenses, two lenses with negative optical power and four lenses with positive optical power.

[0075] The first lens group includes a triplet lens, and the second lens group includes two doublet lenses. Among them, the sixth lens, the seventh lens, and the eighth lens are cemented to form a triplet lens, the ninth lens and the tenth lens are cemented to form a doublet lens, and the eleventh lens and the twelfth lens are cemented to form a doublet lens.

[0076] The parameters of each lens of the imaging lens of this embodiment include the surface type, curvature radius R, thickness d, refractive index Nd of the material, and Abbe number Vd. S1 to S27 represent the surfaces of each lens, cemented lens, aperture STO, and prism SG in the imaging lens, as shown in Table 6 below:

[0077]

[0078]

[0079] Table 6

[0080] Combine Figure 5 As can be seen from the data in Tables 1 and 6, the imaging lens of this embodiment exhibits low distortion, with an absolute distortion value of less than 25%, and image quality reaching 12 megapixels. It also features a large image area, with a full image height of up to 18mm and a large aperture (FNO) of ≤1.8. The lens also exhibits high relative illumination, exceeding 45%, tight assembly tolerances, and a high assembly yield.

[0081] The above description is merely one embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that the present invention is susceptible to various modifications and variations. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the present invention.

Claims

1. An imaging lens comprising, in order from the object side to the image side along the optical axis: A first lens group (G1) comprising at least four lenses, an aperture (STO) and a second lens group (G2) comprising at least four lenses, a total of two lens groups, characterized in that: The image side surface of the lens closest to the aperture side of the first lens group (G1) is convex; The focal power of the lens closest to the aperture stop in the second lens group (G2) is negative, and the object-side surface is concave; The first lens group (G1) and the second lens group (G2) are relatively stationary; The first lens group (G1) includes eight lenses with optical power, and the optical power is arranged in the order of negative-negative-negative-positive-positive-negative-positive-negative; the second lens group (G2) includes six lenses with optical power, and the optical power is arranged in the order of negative-positive-negative-positive-positive-positive.

2. The imaging lens according to claim 1, wherein: The first lens group (G1) includes at least one biconcave lens and at least one biconvex lens.

3. The imaging lens according to claim 1, wherein: The second lens group (G2) includes at least one biconcave lens and at least two biconvex lenses.

4. The imaging lens according to any one of claims 1 to 3, wherein: All lenses in the imaging lens are spherical lenses.

5. The imaging lens according to any one of claims 1 to 3, wherein: The imaging lens comprises at least two cemented lenses.

6. The imaging lens according to any one of claims 1 to 3, wherein: The second lens group (G2) includes at least one doublet lens.

7. The imaging lens according to claim 6, wherein: The focal length Fa of the doublet lens and the focal length F2 of the second lens group (G2) satisfy the relationship: -29.67≤Fa / F2≤11.

89.

8. The imaging lens according to any one of claims 1 to 3 or 6, wherein: The focal length F1 of the first lens group (G1) and the focal length F2 of the second lens group (G2) satisfy the relationship: -78.90≤F1 / F2≤11.

36.

9. The imaging lens according to any one of claims 1 to 3 or 6, wherein: The focal length F1 of the first lens group (G1) and the focal length F of the imaging lens satisfy the relationship: -163.11≤F1 / F≤27.

50.

10. The imaging lens according to any one of claims 1 to 3 or 6, wherein: The refractive index Nd of at least two lenses included in the imaging lens satisfies the relationship: Nd≥1.

8.

11. The imaging lens according to any one of claims 1 to 3 or 6, wherein: The Abbe numbers Vd of at least four lenses included in the imaging lens satisfy the relationship: Vd≤45.

Images