lens

Abstract

This invention relates to a lens, comprising, along the object-side to image-side direction, a first lens group (G1) with positive optical power, a stop, and a second lens group (G2) with positive optical power. The first lens group (G1) and the second lens group (G2) are relatively stationary, and the first lens group (G1) and the second lens group (G2) move together along the optical axis for focusing. The optical back focal length (BFL) of the lens and the optical system length (L) of the lens satisfy the following relationship: 0.2 ≤ BFL / L ≤ 0.3. The lens of this invention features a large aperture (FNO ≤ 1.6), a large sensor area (capable of matching up to a 1.1" chip), a high resolution of up to 12 megapixels, a small size (total length less than 85mm), good color reproduction, a relative illumination (RI) ≥ 60%, and an image plane drift of less than 3μm under high and low temperature conditions (-30℃ to 70℃).

Description

Technical Field

[0001] This invention relates to the field of optical system and device design technology, and in particular to a lens. Background Technology

[0002] Intelligent Transportation Systems (ITS) are a timely, accurate, and efficient transportation management system that operates on a large scale and in all aspects. It effectively integrates advanced computer processing technology, information processing technology, data communication and transmission technology, and electronic control technology into the transportation management system.

[0003] With the development of intelligent transportation systems, the market demands for intelligent transportation lenses are increasing. Currently, while intelligent transportation lenses on the market can meet the requirements of large aperture and large target area, it is difficult to balance the image quality and relative illumination of the optical system, which greatly limits the application environment of the lenses. Summary of the Invention

[0004] The purpose of this invention is to solve the above-mentioned problems and provide a lens with a large aperture, large target surface, high relative illumination, and good color reproduction.

[0005] To achieve the above-mentioned objective of the present invention, the present invention provides a lens, which, along the object-side to image-side direction, sequentially includes a first lens group with positive optical power, an aperture stop, and a second lens group with positive optical power. The first lens group and the second lens group are relatively stationary, and the first lens group and the second lens group move together along the optical axis to focus. The optical back focal length BFL of the lens and the optical system length L of the lens satisfy the following relationship: 0.2≤BFL / L≤0.3.

[0006] According to one aspect of the invention, the first lens group includes three positive power lenses and at least one negative power lens.

[0007] According to one aspect of the invention, the first lens group includes a cemented doublet lens, wherein the object surface of the cemented doublet lens is convex along the object-to-image direction.

[0008] According to one aspect of the invention, along the object-to-image direction, the first lens in the first lens group is a positive power lens and is a convex-concave lens.

[0009] According to one aspect of the invention, along the object-to-image direction, the lens closest to the image side in the first lens group is a negative power lens, and its image side surface is concave.

[0010] According to one aspect of the invention, along the object-to-image direction, the Abbe number of the first lens in the first lens group is VD. L1 The refractive index is ND L1The following relationship is satisfied: 10 ≤ VD L1 ≤30、1.8≤ND L1 ≤2.0.

[0011] According to one aspect of the invention, at least one lens in the first lens group has an Abbe number and a refractive index of VD. Li and ND Li Satisfying: 60≤VD Li ≤96、1.4≤ND Li ≤1.6.

[0012] According to one aspect of the invention, the second lens group comprises three positive power lenses and at least one negative power lens.

[0013] According to one aspect of the invention, the second lens group includes at least one cemented doublet lens.

[0014] According to one aspect of the invention, along the object-to-image direction, the first lens and the second lens in the second lens group constitute a first cemented doublet lens, wherein the object-side surface of the first cemented doublet lens is concave.

[0015] According to one aspect of the invention, along the object-to-image direction, the image-side surface of the lens closest to the image side in the second lens group is either flat or concave.

[0016] According to one aspect of the invention, the focal length of the second lens group is f2, and the focal length of the lens optical system is f, satisfying the relationship: 1.5≤f2 / f≤3.0.

[0017] According to one aspect of the invention, the optical system length of the lens is L, and the target surface diameter of the lens is φ, satisfying the relationship: L / φ≤4.5.

[0018] According to one aspect of the invention, at least one positive power lens in the first lens group has a relative refractive index temperature coefficient dn / dt that satisfies the relationship: -8*10 -6 ≤dn / dt≤-3*10 -6 .

[0019] In the lens of this invention, the primary function of the first lens group is to correct optical aberrations and distortions. The focusing method, which involves the first and second lens groups moving together along the optical axis, effectively reduces the system's tolerance sensitivity, improves image quality at different object distances, and ensures image uniformity. Furthermore, the optical back focal length (BFL) of the lens of this invention satisfies the relationship between the lens's optical system length (L) and the optical system length (BFL / L): 0.2 ≤ BFL / L ≤ 0.3. This configuration effectively enhances the relative illumination over a wide field of view of the optical system, while also facilitating a smaller principal ray incident angle, resulting in higher color reproduction.

[0020] The lens of the present invention includes three positive power lenses and at least one negative power lens in the first lens group. This arrangement, through the reasonable combination of positive and negative power, is beneficial for correcting spherical aberration, astigmatism, and distortion within the first lens group G1, and is conducive to achieving a large aperture, while also reducing tolerance sensitivity within the group.

[0021] The first lens group of the present invention satisfies the above-mentioned limitations, enabling the optical system to smoothly collect incident light, effectively reduce field curvature and astigmatism caused by incident light with a large field of view, and achieve a large aperture while maintaining low distortion.

[0022] The focal length of the second lens group in this invention is f2, and the focal length of the lens optical system is f, satisfying the relationship: 1.5 ≤ f2 / f ≤ 3.0. Satisfying this relationship effectively controls the optical power of the first and second lens groups, ensuring a reasonable match, thereby reducing tolerance sensitivity between groups, improving the imaging quality of the optical system, and ensuring image uniformity.

[0023] The optical system length of the lens of this invention is L, and the target surface diameter of the lens is φ, satisfying the relationship: L / φ≤4.5. Under this relationship, the size of a large image sensor lens can be constrained, which is beneficial to reduce the lens volume, save space, and control costs.

[0024] In the first lens group of this invention, at least one positive power lens has a relative refractive index temperature coefficient dn / dt that satisfies the following relationship: -8*10 -6 ≤dn / dt≤-3*10 -6 Satisfying the above relationship is beneficial for temperature correction of anechoic systems and can more effectively balance the image plane drift of optical systems under high and low temperature conditions.

[0025] The lens of this invention has the characteristics of a large aperture of FNO≤1.6, a large target surface (up to 1.1" chip), a high resolution of up to 12 million pixels, a small size (total length less than 85mm), good color reproduction, relative illumination RI≥60%, and image plane drift of less than 3μm under high and low temperature (-30℃-70℃) conditions. Attached Figure Description

[0026] Figure 1 A schematic diagram illustrating the lens structure according to Embodiment 1 of the present invention;

[0027] Figure 2 A schematic diagram illustrating distortion during focusing at the optimal working object distance of the lens according to Embodiment 1 of the present invention;

[0028] Figure 3A schematic diagram illustrating the chromatic aberration at the optimal working distance of the lens during focusing according to Embodiment 1 of the present invention;

[0029] Figure 4 This schematic diagram illustrates the positional chromatic aberration when focusing at the optimal working distance of the lens according to Embodiment 1 of the present invention.

[0030] Figure 5 This schematic diagram illustrates the MTF chart when focusing at the optimal working object distance of the lens according to Embodiment 1 of the present invention.

[0031] Figure 6 A schematic diagram illustrating the lens structure according to Embodiment 2 of the present invention;

[0032] Figure 7 A schematic diagram illustrating distortion during focusing at the optimal working object distance of the lens according to Embodiment 2 of the present invention;

[0033] Figure 8 A schematic diagram illustrating the magnification chromatic aberration during focusing at the optimal working object distance of the lens according to Embodiment 2 of the present invention;

[0034] Figure 9 This schematic diagram illustrates the positional chromatic aberration when focusing at the optimal working distance of the lens according to Embodiment 2 of the present invention.

[0035] Figure 10 This schematic diagram illustrates the MTF chart when focusing at the optimal working object distance of the lens according to Embodiment 2 of the present invention.

[0036] Figure 11 A schematic diagram illustrating the lens structure according to Embodiment 3 of the present invention;

[0037] Figure 12 A schematic diagram illustrating the distortion during focusing at the optimal working object distance of the lens according to Embodiment 3 of the present invention;

[0038] Figure 13 A schematic diagram illustrating the magnification chromatic aberration during focusing at the optimal working object distance of the lens according to Embodiment 3 of the present invention;

[0039] Figure 14 This schematic diagram illustrates the positional chromatic aberration during focusing at the optimal working distance of the lens according to Embodiment 3 of the present invention.

[0040] Figure 15 This schematic diagram illustrates the MTF chart when focusing at the optimal working object distance of the lens according to Embodiment 3 of the present invention.

[0041] Figure 16 A schematic diagram illustrating the lens structure according to Embodiment 4 of the present invention;

[0042] Figure 17A schematic diagram illustrating the distortion during focusing at the optimal working object distance of the lens according to Embodiment 4 of the present invention;

[0043] Figure 18 A schematic diagram illustrating the magnification chromatic aberration during optimal lens working distance focusing according to Embodiment 4 of the present invention;

[0044] Figure 19 This schematic diagram illustrates the positional chromatic aberration during focusing at the optimal working object distance of the lens according to Embodiment 4 of the present invention.

[0045] Figure 20 This schematic diagram illustrates the MTF chart when focusing at the optimal working object distance of the lens according to Embodiment 4 of the present invention.

[0046] Figure 21 A schematic diagram illustrating the lens structure according to Embodiment 5 of the present invention;

[0047] Figure 22 A schematic diagram illustrating distortion during focusing at the optimal working object distance of the lens according to Embodiment 5 of the present invention;

[0048] Figure 23 A schematic diagram illustrating the magnification chromatic aberration during focusing at the optimal working object distance of the lens according to Embodiment 5 of the present invention;

[0049] Figure 24 This schematic diagram illustrates the positional chromatic aberration during focusing at the optimal working object distance of the lens according to Embodiment 5 of the present invention.

[0050] Figure 25 The diagram illustrates the MTF (Medium-Friction Transformer) at the optimal working distance for focusing according to Embodiment 5 of the present invention. Detailed Implementation

[0051] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly described below. Obviously, the drawings described below are merely some embodiments of the present invention, and those skilled in the art can obtain other drawings based on these drawings without creative effort.

[0052] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. The embodiments cannot be described in detail here, but the embodiments of the present invention are not limited to the following embodiments.

[0053] Reference Figure 1As shown, this invention provides a lens that, along the object-side to image-side direction, sequentially includes a first lens group G1 with positive optical power, an aperture stop (STOP), and a second lens group G2 with positive optical power. The first lens group G1 and the second lens group G2 are relatively stationary. Focusing at different object distances is achieved by the first lens group G1 and the second lens group G2 moving together along the optical axis. In this lens, according to the above-described configuration, the first lens group G1 primarily corrects optical aberrations and distortions. The method of focusing by having the first lens group G1 and the second lens group G2 move together along the optical axis effectively reduces the system's tolerance sensitivity, improves image quality at different object distances, and ensures image uniformity. Furthermore, the optical back focal length (BFL) of this invention satisfies the relationship between the lens's optical system length (L) and the optical system length (BFL / L) as follows: 0.2 ≤ BFL / L ≤ 0.3. This configuration effectively improves the relative illumination of the optical system over a wide field of view and facilitates achieving a smaller principal ray incident angle, resulting in higher image color reproduction.

[0054] The lens of the present invention includes three positive power lenses and at least one negative power lens in the first lens group G1. This arrangement, through the reasonable combination of positive and negative power, is beneficial for correcting spherical aberration, astigmatism, and distortion within the first lens group G1, and is conducive to achieving a large aperture, while also reducing tolerance sensitivity within the group.

[0055] The first lens group G1 of the present invention includes a cemented doublet lens, the object surface of which is convex in the object-to-image direction. Furthermore, the first lens in the first lens group G1 is a positive power lens and is a convex-concave lens in the object-to-image direction. The lens closest to the image side in the first lens group G1 is a negative power lens, and its image side surface is concave.

[0056] The first lens group G1 of the present invention satisfies the above-mentioned limitations, enabling the optical system to smoothly collect incident light, effectively reduce field curvature and astigmatism caused by incident light with a large field of view, and achieve a large aperture while maintaining low distortion.

[0057] The second lens group G2 of this invention includes three positive power lenses and at least one negative power lens, and at least one cemented doublet lens. This arrangement, through the reasonable combination of positive and negative power lenses and the use of cemented doublet lenses, facilitates the correction of spherical aberration, astigmatism, and distortion within the second lens group G2. The correction of aberrations within the second lens group G2 helps reduce the proportion of aberration correction burden on the first lens group G1, thus better reducing the tolerance sensitivity of the group and comprehensively improving the imaging quality of the optical system.

[0058] In this invention, along the object-to-image direction, the first lens and the second lens in the second lens group G2 form a first cemented doublet lens, and the object-side surface of the first cemented doublet lens is concave. The image-side surface of the lens closest to the image side in the second lens group G2 is either flat or concave.

[0059] This setup effectively reduces the tolerance sensitivity of the optical system and ensures sufficient back focus, which helps to achieve a smaller main line offset angle and higher color reproduction.

[0060] Furthermore, the focal length of the second lens group G2 in this invention is f2, and the focal length of the lens optical system is f, satisfying the relationship: 1.5 ≤ f2 / f ≤ 3.0. Satisfying this relationship effectively controls the optical power of the first lens group G1 and the second lens group G2, ensuring a reasonable match, thereby reducing tolerance sensitivity between groups, improving the imaging quality of the optical system, and ensuring image uniformity.

[0061] In the lens of the present invention, along the object-side to image-side direction, the Abbe number of the first lens in the first lens group G1 is VD. L1 The refractive index is ND L1 The following relationship is satisfied: 10 ≤ VD L1 ≤30、1.8≤ND L1 ≤2.0.

[0062] Furthermore, at least one lens in the first lens group G1 has an Abbe number and a refractive index of VD. Li and ND Li Satisfying: 60≤VD Li ≤96、1.4≤ND Li ≤1.6.

[0063] Satisfying the above relationship can effectively reduce the aberrations of the optical system, correct the chromatic aberration and distortion of the optical system, facilitate the temperature correction of the system, control the incident angle of light, reduce tolerance sensitivity, and thus improve the imaging quality of the optical system.

[0064] The optical system length of the lens of this invention is L, and the target surface diameter of the lens is φ, satisfying the relationship: L / φ≤4.5. Under this relationship, the size of a large image sensor lens can be constrained, which is beneficial to reduce the lens volume, save space, and control costs.

[0065] In the lens of this invention, at least one positive power lens in the first lens group G1 has a relative refractive index temperature coefficient dn / dt that satisfies the relationship: -8*10 -6 ≤dn / dt≤-3*10 -6Satisfying the above relationship is beneficial for temperature correction of anechoic systems and can more effectively balance the image plane drift of optical systems under high and low temperature conditions.

[0066] In summary, the lens of the present invention has the characteristics of a large aperture of FNO≤1.6, a large target surface (up to 1.1" chip), a high resolution of up to 12 million pixels, a small size (total length less than 85mm), good color reproduction, relative illumination RI≥60%, and image plane drift of less than 3μm under high and low temperature (-30℃-70℃) conditions.

[0067] The following five specific embodiments based on the above-described configuration of the present invention are given to illustrate the lens according to the present invention.

[0068] The data for the five implementation methods are shown in Table 1 below:

[0069] Conditional expression Example 1 Example 2 Example 3 Example 4 Example 5 1.5 ≤ f² / f ≤ 3.0 2.34 1.60 1.83 1.82 2.97 0.2 ≤ BFL / L ≤ 0.3 0.30 0.24 0.23 0.23 0.26 L / φ≤4.50 4.14 4.27 4.27 4.50 4.10

[0070] Table 1

[0071] Implementation Method 1:

[0072] Figure 1 This is a schematic diagram illustrating the lens structure according to Embodiment 1 of the present invention.

[0073] Table 2 below lists the relevant parameters of each lens in this embodiment, including surface type, radius of curvature, thickness, refractive index of the material, and Abbe number:

[0074] Face number Surface type R value thickness Refractive index Abbe number sur1 standard 30.106 5.10 1.95 18.0 sur2 standard 70.652 3.24 sur3 standard 40.368 4.46 1.50 81.6 sur4 standard 95.631 0.10 sur5 standard 19.354 6.34 1.62 63.4 sur6 standard -425.367 3.26 1.95 18.0 sur7 standard 13.684 6.00 Stop standard infinity 3.24 sur9 standard -29.843 0.80 1.83 42.7 sur10 standard 10.301 4.69 1.85 23.8 sur11 standard -29.816 4.37 sur12 standard -17.643 1.64 1.32 30.1 sur13 standard 91.634 3.87 1.70 49.0 sur14 standard -21.348 0.10 sur15 standard 40.563 3.65 1.85 41.5 sur16 standard infinity 21.95 Image

[0075] Table 2

[0076] In this embodiment, the effective focal length of the lens is f = 49.96 mm, the aperture is FNO = 1.4, and the total length of the optical system is TTL = 72.81 mm. The first lens group G1 contains four lenses, labeled L1-L4, and the second lens group G2 contains five lenses, labeled L5-L9. Lenses L3 and L4 form a cemented doublet. Lenses L5 and L6, and lenses L7 and L8, each form a cemented doublet. In the first lens group G1, lens L4 is a negative power lens, and lenses L1-L3 are positive power lenses. In the second lens group G2, the three positive power lenses are L6, L8, and L9, and the negative power lenses are L5 and L7.

[0077] In the first lens group G1, lens L1 has a refractive index of 1.95 and an Abbe number of 18.0. Lens L2 has a refractive index of 1.50 and an Abbe number of 81.6. The relative refractive index temperature coefficient of lens L2 is -6.2 × 10⁻⁶. -6The relative refractive index temperature coefficient of lens L3 is -3.2*10. -6 .

[0078] Figure 2-4 The diagrams illustrate the distortion, magnification chromatic aberration, positional chromatic aberration, and MTF of the lens in Embodiment 1 at optimal working object distance focusing. Referring to the accompanying drawings, it can be seen that the variable lens obtained according to Embodiment 1 of the present invention has the characteristics of small size, large aperture, large target area, high resolution, high color fidelity, high relative illumination, and image plane drift of less than 3μm under high and low temperature conditions.

[0079] Implementation Method Two:

[0080] Figure 3 This is a schematic diagram illustrating the lens structure according to Embodiment 2 of the present invention.

[0081] Table 3 below lists the relevant parameters of each lens in this embodiment, including surface type, radius of curvature, thickness, refractive index of the material, and Abbe number:

[0082] Face number Surface type R value thickness Refractive index Abbe number sur1 standard 32.994 3.89 1.92 20.9 sur2 standard 73.642 0.10 sur3 standard 34.58 4.46 1.46 90.2 sur4 standard 126.571 0.10 sur5 standard 21.385 6.34 1.59 68.6 sur6 standard 186.278 5.26 1.81 22.8 sur7 standard 13.964 6.00 Stop standard infinity 5.24 sur9 standard -21.861 1.08 1.80 46.6 sur10 standard 29.374 5.69 1.81 25.4 sur11 standard -42.591 9.03 sur12 standard 92.316 2.64 1.95 18.0 sur13 standard -75.642 0.20 sur14 standard 25.612 6.21 1.92 18.4 sur15 standard -53.806 1.24 1.62 50.5 sur16 standard 24.735 17.68 Image

[0083] Table 3

[0084] In this embodiment, the effective focal length of the lens is f = 50.00 mm, the aperture is FNO = 1.5, and the total length of the optical system is TTL = 75.16 mm. The first lens group G1 contains four lenses, labeled L1-L4, and the second lens group G2 contains five lenses, labeled L5-L9. Lenses L3 and L4 form a cemented doublet. Lenses L5 and L6, and lenses L8 and L9, each form a cemented doublet. In the first lens group G1, lens L4 is a negative power lens, and lenses L1-L3 are positive power lenses. In the second lens group G2, the three positive power lenses are L6, L7, and L8, and the negative power lenses are L5 and L9.

[0085] In the first lens group G1, lens L1 has a refractive index of 1.92 and an Abbe number of 20.9. Lens L2 has a refractive index of 1.46 and an Abbe number of 90.2. The relative refractive index temperature coefficient of lens L2 is -6.2 × 10⁻⁶. -6 The relative refractive index temperature coefficient of lens L3 is -5.7*10. -6 .

[0086] Figure 6-10The diagrams illustrate the distortion, magnification chromatic aberration, positional chromatic aberration, and MTF of the lens in Embodiment 2 at optimal working object distance focusing. Referring to the accompanying drawings, it can be seen that the variable lens obtained according to Embodiment 2 of the present invention has the characteristics of small size, large aperture, large target area, high resolution, high color fidelity, high relative illumination, and image plane drift of less than 2μm under high and low temperature conditions.

[0087] Implementation Method 3:

[0088] Figure 11 This is a schematic diagram illustrating the lens structure according to Embodiment 3 of the present invention.

[0089] Table 4 below lists the relevant parameters of each lens in this embodiment, including surface type, radius of curvature, thickness, refractive index of the material, and Abbe number:

[0090] Face number Surface type R value thickness Refractive index Abbe number sur1 standard 42.486 3.04 1.99 16.5 sur2 standard 72.605 0.10 sur3 standard 34.156 5.46 1.44 95.1 sur4 standard 137.584 0.10 sur5 standard 21.868 6.00 1.59 68.6 sur6 standard 87.695 6.00 1.81 22.7 sur7 standard 15.674 6.50 Stop standard infinity 5.47 sur9 standard -23.546 2.00 1.74 27.8 sur10 standard 19.616 6.00 1.90 37.4 sur11 standard -45.516 6.48 sur12 standard 53.762 3.21 1.83 42.7 sur13 standard -32.931 0.85 sur14 standard -26.735 1.00 1.52 64.2 sur15 standard 19.328 6.00 1.83 42.7 sur16 standard infinity 16.95 Image

[0091] Table 4

[0092] In this embodiment, the effective focal length of the lens is f = 47.56 mm, the aperture is FNO = 1.48, and the total length of the optical system is TTL = 75.16 mm. The first lens group G1 contains four lenses, labeled L1-L4, and the second lens group G2 contains five lenses, labeled L5-L9. Lenses L3 and L4 form a cemented doublet. Lenses L5 and L6, and lenses L8 and L9 each form a cemented doublet. In the first lens group G1, lens L4 is a negative power lens, and lenses L1-L3 are positive power lenses. In the second lens group G2, the three positive power lenses are L6, L7, and L9, and the negative power lenses are L5 and L8.

[0093] In the first lens group G1, lens L1 has a refractive index of 1.99 and an Abbe number of 16.5. Lens L2 has a refractive index of 1.44 and an Abbe number of 95.1. The relative refractive index temperature coefficient of lens L2 is -6.3 × 10⁻⁶. -6 The relative refractive index temperature coefficient of lens L3 is -5.7*10. -6 .

[0094] Figure 12-15 The diagrams illustrate the distortion, magnification chromatic aberration, positional chromatic aberration, and MTF of the lens in Embodiment 3 at optimal working object distance focusing. Referring to the accompanying drawings, it can be seen that the variable lens obtained according to Embodiment 3 of the present invention has the characteristics of small size, large aperture, large target area, high resolution, high color fidelity, high relative illumination, and image plane drift of less than 3μm under high and low temperature conditions.

[0095] Implementation Method 4

[0096] Figure 16 This is a schematic diagram illustrating the lens structure according to Embodiment 4 of the present invention.

[0097] Table 5 below lists the relevant parameters of each lens in this embodiment, including surface type, radius of curvature, thickness, refractive index of the material, and Abbe number:

[0098] Face number Surface type R value thickness Refractive index Abbe number sur1 standard 32.678 4.43 1.87 20.0 sur2 standard 73.581 6.95 sur3 standard 35.267 4.89 1.55 75.5 sur4 standard 108.145 0.12 sur5 standard 21.365 4.89 1.64 60.2 sur6 standard 458.642 3.68 1.81 22.8 sur7 standard 12.954 7.78 Stop standard infinity 2.59 sur9 standard -26.348 0.92 1.70 30.1 sur10 standard 15.982 3.06 1.73 54.7 sur11 standard -31.942 5.34 sur12 standard 75.942 6.74 1.85 23.8 sur13 standard -21.954 5.69 1.52 64.2 sur14 standard 18.951 5.34 1.91 35.5 sur15 standard 55.982 18.96 Image

[0099] Table 5

[0100] In this embodiment, the effective focal length of the lens is f = 51.5mm, the aperture is FNO = 1.50, and the total length of the optical system is TTL = 81.38mm. The first lens group G1 contains four lenses, labeled L1-L4, and the second lens group G2 contains five lenses, labeled L5-L9. Lenses L3 and L4 form a cemented doublet. Lenses L5 and L6 form a cemented doublet, and lenses L7, L8, and L9 form a cemented triplicate. In the first lens group G1, lens L4 is a negative power lens, and lenses L1-L3 are positive power lenses. In the second lens group G2, the three positive power lenses are L6, L7, and L9, and the negative power lenses are L5 and L8.

[0101] In the first lens group G1, lens L1 has a refractive index of 1.87 and an Abbe number of 20.0. Lens L2 has a refractive index of 1.55 and an Abbe number of 75.5. The relative refractive index temperature coefficient of lens L2 is -5.6 × 10⁻⁶. -6 .

[0102] Figure 17-20 The diagrams illustrate the distortion, magnification chromatic aberration, positional chromatic aberration, and MTF of the lens in Embodiment 4 at optimal working object distance focusing. Referring to the accompanying drawings, it can be seen that the variable lens obtained according to Embodiment 4 of the present invention has the characteristics of small size, large aperture, large target area, high resolution, high color fidelity, high relative illumination, and image plane drift of less than 3μm under high and low temperature conditions.

[0103] Example 5

[0104] Figure 21 This is a schematic diagram illustrating the lens structure according to Embodiment 5 of the present invention.

[0105] Table 6 below lists the relevant parameters of each lens in this embodiment, including surface type, radius of curvature, thickness, refractive index of the material, and Abbe number:

[0106] Face number Surface type R value thickness Refractive index Abbe number sur1 standard 52.373 4.59 1.92 20.9 sur2 standard 502.384 0.14 sur3 standard 35.536 2.86 1.50 81.6 sur4 standard 51.069 0.10 sur5 standard 23.291 0.60 1.69 31.2 sur6 standard 18.209 6.45 1.55 75.5 sur7 standard 48.686 5.00 Sur8 standard 41.905 0.60 1.81 22.7 sur9 standard 12.786 4.22 Stop standard infinity 5.25 sur11 standard -23.013 0.60 1.81 22.7 sur12 standard 19.534 4.47 1.90 37.4 sur13 standard -39.472 8.15 sur14 standard 68.185 2.76 1.92 20.9 sur15 standard -57.124 0.10 sur16 standard 23.740 7.46 1.83 42.7 sur17 standard 24.192 18.82 Image

[0107] Table 6

[0108] In this embodiment, the effective focal length of the lens is f = 44.67 mm, the aperture is FNO = 1.48, and the total length of the optical system is TTL = 72.17 mm. The first lens group G1 contains five lenses, numbered L1-L5, and the second lens group G2 contains three lenses, numbered L6-L9. Lenses L3 and L4 form a cemented doublet, and lenses L6 and L7 form a cemented doublet. In the first lens group G1, lens L5 is a negative power lens, and the three positive power lenses are L1, L2, and L4. In the second lens group G2, the three positive power lenses are L7, L8, and L9, and the negative power lens is L6.

[0109] In the first lens group G1, lens L1 has a refractive index of 1.92 and an Abbe number of 20.9. Lens L2 has a refractive index of 1.50 and an Abbe number of 81.6. The relative refractive index temperature coefficient of lens L2 is -6.2 × 10⁻⁶. -6 The relative refractive index temperature coefficient of lens L4 is -5.6*10. -6 .

[0110] Figure 22-25 The diagrams illustrate the distortion, magnification chromatic aberration, positional chromatic aberration, and MTF of the lens in Embodiment 5 at optimal working object distance focusing. Referring to the accompanying drawings, it can be seen that the variable lens obtained according to Embodiment 5 of the present invention has the characteristics of small size, large aperture, large target area, high resolution, high color fidelity, high relative illumination, and image plane drift of less than 2μm under high and low temperature conditions.

[0111] The above description is merely one embodiment of the present invention and is not intended to limit the invention. Those skilled in the art will recognize that the present invention can be modified and varied in various ways. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A lens, characterized in that, Along the object-to-image direction, the lens comprises a first lens group (G1) with positive optical power, an aperture stop (STOP), and a second lens group (G2) with positive optical power, totaling two lens groups. The first lens group (G1) and the second lens group (G2) are relatively stationary, and the first lens group (G1) and the second lens group (G2) move together along the optical axis for focusing. The optical back focal length (BFL) of the lens satisfies the following relationship with the optical system length (L): 0.2 ≤ BFL / L ≤ 0.

3. When the first lens group (G1) consists of four lenses with optical power, the optical power arrangement along the object-to-image direction is: positive optical power, positive optical power, positive optical power, negative optical power; when the second lens group (G2) consists of five lenses with optical power, the optical power arrangement along the object-to-image direction is: negative optical power, positive optical power, negative optical power, positive optical power, positive optical power, or... Negative power, positive power, positive power, negative power, positive power; or When the first lens group (G1) consists of five lenses with optical power, the optical power is arranged along the object side to the image side as follows: positive optical power, positive optical power, negative optical power, positive optical power, negative optical power; when the second lens group (G2) consists of four lenses with optical power, the optical power is arranged along the object side to the image side as follows: negative optical power, positive optical power, positive optical power, positive optical power.

2. The lens according to claim 1, characterized in that, The last two lenses in the first lens group (G1) form a cemented doublet lens, and the object surface of the cemented doublet lens is convex along the object-to-image direction.

3. The lens according to claim 1, characterized in that, Along the object-to-image direction, the first lens in the first lens group (G1) is a positive power lens and is a convex-concave lens.

4. The lens according to claim 1, characterized in that, Along the object-to-image direction, the lens closest to the image side in the first lens group (G1) is a negative power lens, and its image side is concave.

5. The lens according to claim 1 or 3, characterized in that, Along the object-to-image direction, the Abbe number of the first lens in the first lens group (G1) is VD. L1 The refractive index is ND L1 The following relationship is satisfied: 10 ≤ VD L1 ≤30、1.8≤ND L1 ≤2.

0.

6. The lens according to claim 1, characterized in that, The first lens group (G1) has at least one lens with an Abbe number and a refractive index of VD. Li and ND Li Satisfying: 60≤VD Li ≤96、1.4≤ND Li ≤1.

6.

7. The lens according to claim 1, characterized in that, The first two lenses in the second lens group (G2) form a cemented doublet lens.

8. The lens according to claim 7, characterized in that, Along the object-to-image direction, the first and second lenses in the second lens group (G2) form a first cemented doublet lens, and the object-side surface of the first cemented doublet lens is concave.

9. The lens according to claim 1 or 8, characterized in that, Along the object-to-image direction, the image-side surface of the lens closest to the image side in the second lens group (G2) is either flat or concave.

10. The lens according to claim 1, characterized in that, The focal length of the second lens group (G2) is f2, and the focal length of the lens optical system is f, satisfying the relationship: 1.82≤f2 / f≤3.

0.

11. The lens according to claim 1, characterized in that, The optical system of the lens has a length of L and a target surface diameter of φ, satisfying the relationship: L / φ≤4.

5.

12. The lens according to claim 1, characterized in that, At least one positive power lens in the first lens group (G1) has a relative refractive index temperature coefficient dn / dt that satisfies the following relationship: -8*10 -6 ≤dn / dt≤-3*10 -6 .

Images