Industrial lens and optical equipment

Abstract

The invention discloses an industrial lens and optical equipment, the industrial lens comprises a first lens group, a diaphragm and a second lens group which are coaxially arranged in sequence, the first lens group comprises a first lens, a second lens, a third lens and a fourth lens which are sequentially arranged from an object space to an image space along an optical axis, the first lens, the second lens and the fourth lens have positive focal power, and the third lens has negative focal power; the second lens group comprises a fifth lens, a sixth lens, a seventh lens and an eighth lens which are sequentially arranged from the object space to the image space along the optical axis, the fifth lens, the seventh lens and the eighth lens have positive focal power, and the sixth lens has negative focal power; the industrial lens satisfies the following relational expression: 4.3 < = FOV / CRA < = 5.6; 13 < = (fu1 + fu2) / IH < = 26; fOV / (D * TTL) > = 0.025; wherein FOV is the maximum field angle of the industrial lens, CRA is the main ray incident angle of the industrial lens, fu1 is the effective focal length of the first lens group in the industrial lens, fu2 is the effective focal length of the second lens group in the industrial lens, IH is the maximum image plane height of the industrial lens, D is the head aperture size of the industrial lens, and RA is the main ray incident angle of the industrial lens. TTL is the total optical length of the industrial lens. The miniature industrial lens is large in image plane, low in distortion, low in chromatic aberration and high in resolution.

Description

Technical Field

[0001] The present application relates to the field of industrial lens design, and in particular to an industrial lens and optical equipment. Background Art

[0002] As one of the core components of industrial automation systems, industrial lenses are the most advanced components for acquiring image data. They play a decisive role in the accuracy of information acquisition and play a vital role in machine vision systems. Given the particularity of industrial requirements, industrial lenses often need to have higher performance than ordinary lenses, especially in terms of image quality and size. High-precision, high-resolution industrial lenses can help industrial equipment better complete complex tasks, improve product quality and production efficiency, and thus achieve the goal of intelligent manufacturing. Although there are some high-performance industrial lenses on the market, there are still many shortcomings in practical applications.

[0003] Existing industrial lens design solutions usually focus on improving performance in one aspect, such as imaging resolution or miniaturization, but it is difficult to take into account the needs of many aspects. Although they can provide a larger imaging target area, due to the limitations of structural design, there are common problems such as imaging distortion and large size, which makes it difficult for the lens to meet actual needs in application scenarios with high precision requirements, limiting the further improvement and development of industrial automation.

[0004] In response to the above requirements, existing industrial lenses still have certain deficiencies and defects, especially the inability to ensure excellent image quality while ensuring that the entire industrial lens has a larger imaging target surface and good portability. Therefore, how to achieve miniaturization, large target surface and low distortion of industrial lenses while ensuring imaging quality has become a key issue that needs to be solved in this field. Summary of the invention

[0005] In order to achieve the requirements of large image surface, low distortion and miniaturized lenses, meet the high precision and high resolution of industrial lenses, and further improve industrial automation, the present application provides an industrial lens and optical equipment.

[0006] In the first aspect, the present application provides an industrial lens, which adopts the following technical solution: An industrial lens, comprising a first lens group, an aperture, and a second lens group coaxially arranged in sequence, wherein the first lens group comprises a first lens, a second lens, a third lens, and a fourth lens arranged in sequence from the object side to the image side along the optical axis, wherein the first lens, the second lens, and the fourth lens have positive optical power, and the third lens has negative optical power; The second lens group includes 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 fifth lens, the seventh lens and the eighth lens have positive optical power, and the sixth lens has negative optical power; Industrial lenses satisfy the following relationship: 4.3≤FOV / CRA≤5.6; 13≤(f u1 +f u2 ) / IH≤26; FOV / (D*TTL)≥0.025; Wherein, FOV is the maximum field of view angle of the industrial lens, CRA is the incident angle of the main light of the industrial lens, and f u1 is the effective focal length of the first lens group in the industrial lens, f u2 is the effective focal length of the second lens group in the industrial lens, IH is the maximum image plane height of the industrial lens, D is the head aperture size of the industrial lens, and TTL is the total optical length of the industrial lens.

[0007] By adopting the above technical scheme, the relationship between the maximum field of view angle of the industrial lens and the incident angle of the main light is controlled, and the position of each lens in the industrial lens group is reasonably allocated to ensure the minimum distortion of the industrial lens; by reasonably allocating the optical focal length of the first lens group and the second lens group, the demand for large target surface imaging of the industrial lens is met; by controlling the relationship between the maximum field of view angle of the industrial lens, the head aperture size and the total optical length, the miniaturization of the industrial lens is achieved.

[0008] Preferably, the first lens and the second lens are positive meniscus lenses convex toward the object side, the third lens is a double concave negative lens, the fourth lens is a double convex positive lens, the fifth lens is a plano-convex positive lens, the sixth lens is a double concave negative lens, the seventh lens is a positive meniscus lens convex toward the image side, and the eighth lens is a double convex positive lens.

[0009] Preferably, the first lens is a biconvex positive lens, the second lens is a meniscus positive lens convex toward the object side, the third lens is a biconcave negative lens, the fourth lens is a biconvex positive lens, the fifth lens is a meniscus positive lens convex toward the image side, the sixth lens is a biconcave negative lens, the seventh lens is a meniscus positive lens convex toward the image side, and the eighth lens is a biconvex positive lens.

[0010] Preferably, the first lens is a biconvex positive lens, the second lens is a meniscus positive lens convex toward the object side, the third lens is a biconcave negative lens, the fourth lens is a biconvex positive lens, the fifth lens is a biconvex positive lens, the sixth lens is a biconcave negative lens, the seventh lens is a meniscus positive lens convex toward the image side, and the eighth lens is a biconvex positive lens.

[0011] By adopting the above technical solution, three feasible lens shapes of each lens in the industrial lens are given, which provides a basis for the specific implementation of this solution.

[0012] Preferably, the industrial lens also satisfies the following relationship: |f u1 / f|≤8.1; |f u2 / f|≥0.86; Wherein f is the effective focal length of the industrial lens.

[0013] By adopting the above technical solution, the proportion of the optical power of the first lens group and the second lens group to the optical power of the entire lens is reasonably allocated, thereby achieving the demand for high resolution and ensuring the clarity of the image.

[0014] Preferably, the fifth lens and the sixth lens are double-cemented lenses, and are glass lenses.

[0015] By adopting the above technical solution, a cemented lens is used to correct the aberration of the optical lens, thereby eliminating or balancing the chromatic aberration produced by the lens, reducing tolerance sensitivity, and improving the imaging resolution of the optical imaging lens; and the glass lens can effectively improve the stability and durability of the lens group.

[0016] Preferably, the industrial lens also satisfies the following relationship: 35≤|VD5-VD6|≤43, Wherein VD5 is the Abbe number of the fifth lens, and VD6 is the Abbe number of the sixth lens.

[0017] By adopting the above technical solution and reasonably selecting the Abbe numbers of the fifth lens and the sixth lens constituting the cemented lens, the chromatic aberration of the optical system can be effectively reduced.

[0018] Preferably, the industrial lens also satisfies the following relationship: Nd4≥1.8, Wherein Nd4 is the refractive index of the lens material of the fourth lens in the industrial lens at the Fraunhofer spectrum line.

[0019] By adopting the above technical solution and controlling the refractive index of the fourth lens, it is helpful to achieve the miniaturization of industrial lenses.

[0020] Preferably, the industrial lens also satisfies the following relationship: Nd5≤1.7; VD5≥63; Wherein Nd5 is the refractive index of the lens material of the fifth lens in the industrial lens at the Fraunhofer spectrum line, and VD5 is the Abbe number of the fifth lens.

[0021] By adopting the above technical solution and using thermal drift-friendly glass as the material of the fifth lens, the stability of the lens group can be effectively improved.

[0022] In a second aspect, the present application provides an optical device, which adopts the following technical solution: An optical device comprises any one of the industrial lenses described above.

[0023] In summary, this application has at least the following beneficial effects: (1) The present application controls the maximum field of view angle and the incident angle of the main light ray, and reasonably allocates the positions of the lenses in the industrial lens, thereby achieving the requirement of low distortion while maintaining the optical performance of the lens.

[0024] (2) The present application optimizes the optical performance by introducing a cemented lens into the imaging system and controlling the Abbe number of the cemented lens, thereby reducing the chromatic aberration of the imaging, improving the imaging resolution, and ensuring the stability of the lens.

[0025] (3) The present application divides the industrial lens into a first lens group and a second lens group. By reasonably allocating the optical focal lengths of the two, it is possible to achieve large-target imaging of the optical system while maintaining the clarity of the imaging.

[0026] (4) The present application achieves the miniaturization of industrial lenses by controlling the relationship between the maximum field of view angle, head aperture size, and total optical length of the industrial lens. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a lens configuration diagram of an industrial lens in an embodiment of the present application; Figure 2 is a schematic diagram of the optical path of Example 1 of the present application; Figure 3 is a modulation transfer function diagram of Example 1 of the present application; Figure 4 is a schematic diagram of field curvature / F-Tan(θ) distortion of Example 1 of the present application; Figure 5 is a schematic diagram of vertical axis chromatic aberration in Example 1 of the present application; Figure 6 is an axial aberration curve diagram of Example 1 of the present application; Figure 7 is a schematic diagram of the optical path of Example 2 of the present application; Figure 8 is a modulation transfer function diagram of Example 2 of the present application; Fig. 9 is a schematic diagram of field curvature / F-Tan(θ) distortion of Example 2 of the present application; Fig.10 is a schematic diagram of vertical axis chromatic aberration in Example 2 of the present application; Fig.11 is an axial aberration curve diagram of Example 2 of the present application; Fig.12 is a schematic diagram of the optical path of Example 3 of the present application; Fig.13 is a modulation transfer function diagram of Example 3 of the present application; Fig.14 is a schematic diagram of field curvature / F-Tan(θ) distortion of Example 3 of the present application; Fig.15 is a schematic diagram of vertical axis chromatic aberration in Example 3 of the present application; Fig.16 It is the axial aberration curve diagram of Example 3 of the present application.

[0028] Description of reference numerals: 1. First lens group; 2. Aperture; 3. Second lens group; 4. First lens; 5. Second lens; 6. Third lens; 7. Fourth lens; 8. Fifth lens; 9. Sixth lens; 10. Seventh lens; 11. Eighth lens; 12. Imaging surface. DETAILED DESCRIPTION

[0029] The present application provides an industrial lens and an optical device. To make the purpose, technical solution and advantages of the present application clearer, the implementation methods of the present application will be further described in detail below.

[0030] The technical solutions in some embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the specification. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0031] It should be noted that in this specification, the expressions of first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the features. Therefore, without departing from the teaching of the present invention, the first lens discussed below may also be referred to as the second lens or the third lens.

[0032] This application proposes an industrial lens, such as Figure 1 As shown, it includes a first lens group 1, an aperture 2, a second lens group 3 and an imaging surface 12 which are coaxially arranged in sequence. The first lens group 1 includes a first lens 4, a second lens 5, a third lens 6 and a fourth lens 7 which are arranged in sequence from the object side to the image side along the optical axis. The first lens 4, the second lens 5 and the fourth lens 7 have positive optical power, and the third lens 6 has negative optical power. The second lens group 3 includes a fifth lens 8, a sixth lens 9, a seventh lens 10 and an eighth lens 11 which are arranged in sequence from the object side to the image side along the optical axis. The fifth lens 8, the seventh lens 10 and the eighth lens 11 have positive refractive power, and the sixth lens 9 has negative refractive power. Industrial lenses satisfy the following relationship: 4.3≤FOV / CRA≤5.6; 13≤(f u1 +f u2 ) / IH≤26; FOV / (D*TTL)≥0.025; Among them, FOV is the maximum field of view of the industrial lens, CRA is the incident angle of the main light of the industrial lens, and f u1 is the effective focal length of the first lens group 1 in the industrial lens, f u2 is the effective focal length of the second lens group 3 in the industrial lens, IH is the maximum image plane height of the industrial lens, D is the head aperture size of the industrial lens, and TTL is the total optical length of the industrial lens, that is, the distance from the center of the object side of the first lens 4 to the imaging plane 12.

[0033] In some embodiments of the present application, the entire industrial lens is divided into two front and rear lens groups according to the orientation from object to image. The front lens group close to the object is the first lens group 1, and the rear lens group close to the image is the second lens group 3. The two lens groups are separated by an aperture 2 (i.e., ST0). The aperture 2 controls the imaging quality and the performance of the optical system by limiting the propagation range and direction of the light beam. The reasonable allocation of the optical focal length of the front lens group and the rear lens group can realize large target surface imaging of the optical system.

[0034] Through the above relationship, the industrial lens can ensure the clarity of the image while imaging on a large target surface, and at the same time, the industrial lens can be miniaturized.

[0035] In the embodiment of the present application, the optical power f of the first lens group 1 is u1 , the focal length f of the second lens group 3 u2 They satisfy the following relationship with the effective focal length f of the entire industrial lens: |f u1 / f|≤8.1; |f u2 / f|≥0.86.

[0036] Through the above-mentioned proportion constraints, the high-resolution requirements of industrial lenses are met and the clarity of the image is guaranteed.

[0037] In the embodiment of the present application, the fifth lens 8 and the sixth lens 9 are double-cemented lenses, and are glass lenses. The cemented lenses can correct the aberration of the lens, balance the chromatic aberration produced by the lens, and improve the imaging resolution, and the use of glass material can effectively improve the stability and durability of the lens group.

[0038] In the embodiment of the present application, the Abbe number VD5 of the fifth lens 8 and the Abbe number VD6 of the sixth lens 9 of the doublet lens satisfy the following relationship: 35≤|VD5-VD6|≤43, Controlling the Abbe number of the cemented lens within the above range can effectively reduce the chromatic aberration of the optical system.

[0039] In the embodiment of the present application, the refractive index Nd5 of the cemented lens fifth lens 8 and the Abbe number VD5 of the fifth lens 8 satisfy the following relationship: Nd5≤1.7; VD5≥63; Controlling the Abbe number of the fifth lens 8 further improves the clarity of the image. Using thermal drift-friendly glass for the fifth lens 8 can effectively improve the stability of the lens group.

[0040] In the embodiment of the present application, the refractive index Nd4 of the fourth lens 7 at the Fraunhofer line also satisfies the following relationship: Nd4 ≥ 1.8, High refractive index materials can be used to control the refractive index of the fourth lens, which helps to achieve miniaturization of industrial lenses.

[0041] In an embodiment of the present application, the industrial lens is provided with a first lens 4, a second lens 5, a third lens 6, a fourth lens 7, an aperture 2, a fifth lens 8, a sixth lens 9, a seventh lens 10, an eighth lens 11 and an imaging surface 12 in sequence along the optical axis from the object side to the image side.

[0042] Among them, the first lens 4 has positive focal length, and its curved shape is conducive to the industrial lens to obtain light at a large angle; the second lens 5 has positive focal length, which can compress the light collected by the first lens 4, so that the light can smoothly transition to the rear optical system, which is conducive to more uniform brightness of the picture; The third lens 6 has a negative focal length, which can diverge the light collected by the second lens 5, so that the light smoothly transitions to the rear optical system, and the focal length is reasonably controlled; The fourth lens 7 has positive refractive power and can focus the light collected by the third lens 6 so that the light is more evenly irradiated to the target area; And the fourth lens 7 can make TTL ≤ 59.53 mm by reasonably controlling the optical focal length, so as to meet the miniaturization requirements; The aperture 2 is placed between the fourth lens 7 and the fifth lens 8 to control the imaging quality and the performance of the optical system by limiting the propagation range and direction of the light beam; The fifth lens 8 and the sixth lens 9 are double-cemented lenses, which are used to eliminate or balance the chromatic aberration and distortion produced by the lens and reduce the tolerance sensitivity; The fifth lens 8 has positive focal power, the sixth lens 9 has negative focal power, and both are glass lenses, which can effectively improve the stability and durability of the lens group.

[0043] The seventh lens 10 has positive refractive power, can focus the light collected by the cemented lens, and correct the aberration, thereby optimizing the imaging performance of the lens group.

[0044] The eighth lens 11 has positive refractive power and can focus the light collected by the seventh lens 10, which is beneficial to the field correction of the lens and optimizes the imaging performance of the lens group.

[0045] Three different embodiments of industrial lenses that conform to the above-mentioned scheme are given below as specific implementation methods of the present application.

[0046] Embodiment 1: This embodiment provides an industrial lens, such as Figure 2 As shown, in Example 1, the first lens 4 and the second lens 5 are positive meniscus lenses convex to the object side, the third lens 6 is a double concave negative lens, the fourth lens 7 is a double convex positive lens, the fifth lens 8 is a plano-convex positive lens, the sixth lens 9 is a double concave negative lens, the seventh lens 10 is a positive meniscus lens convex to the image side, and the eighth lens 11 is a double convex positive lens.

[0047] Based on the structure of the industrial lens provided in the above-mentioned embodiment 1, the industrial lens includes a meniscus positive lens convex toward the object side, a meniscus positive lens convex toward the object side, a double concave negative lens, a double convex positive lens, an aperture 2, a plano-convex positive lens, a double concave negative lens, a meniscus positive lens convex toward the image side, a double convex positive lens and an imaging surface 12, which are coaxially arranged in sequence. Table 1 shows various parameters of multiple lenses of the industrial lens.

[0048] Table 1: Combination Figure 1 and Figure 2 As shown, the object side surface S1 of the first lens 4, i.e., the meniscus positive lens, is a convex surface, and the image side surface S2 is a concave surface; The object side surface S3 of the second lens 5, i.e., the meniscus positive lens, is convex, and the image side surface S4 is concave; The object side surface S5 of the third lens element 6, i.e., the double concave negative lens, is concave, and the image side surface S6 is concave; The fourth lens element 7, i.e., a biconvex positive lens, has an object side surface S7 which is convex, and an image side surface S8 which is convex; The fifth lens element 8, i.e., a plano-convex positive lens, has a flat object-side surface S10 and a convex image-side surface S11; The object side surface S11 of the sixth lens element 9, i.e., the double concave negative lens, is a concave surface, and the image side surface S12 is a concave surface; The fifth lens 8 and the sixth lens 9 are cemented lenses and share S11, so S11 is convex relative to the fifth lens 8 and concave relative to the sixth lens 9; The object side surface S13 of the seventh lens element 10, i.e., the positive meniscus lens, is a concave surface, and the image side surface S14 is a convex surface; The object side surface S15 of the eighth lens 11, i.e., the biconvex positive lens, is a convex surface, and the image side surface S16 is a convex surface; IMA is the imaging surface.

[0049] In this embodiment 1, the parameters of the industrial lens are shown in Table 2.

[0050] Table 2: It can be seen from Table 2 above that in this embodiment 1, the relationship between the maximum field of view FOV of the industrial lens and the main ray incident angle CRA of the industrial lens is: FOV / CRA=4.3886, satisfying the relationship 4.3≤FOV / CRA≤5.6; The effective focal length f of the first lens group 1 u1 , the effective focal length f of the second lens group 3 u2 , the maximum image plane height IH: (f u1 +f u2 ) / IH=13.0632, satisfying the relationship 13≤(f u1 +f u2 ) / IH≤26; The relationship between the maximum field of view FOV, the head aperture size D, and the total optical length of the industrial lens is: TTLFOV / (D*TTL)=0.0299, satisfying the relationship FOV / (D*TTL)≥0.025; The focal length f of the first lens group 1 u1 , and the relationship between the effective focal length f of the entire industrial lens: |f u1 / f|=3.5230, satisfying the relationship |f u1 / f|≤8.1; The focal length f of the second lens group 3 u2 , and the relationship between the effective focal length f of the entire industrial lens: |f u2 / f|=1.1793, satisfying the relationship |f u2 / f|≥0.86; The relationship between the Abbe number VD5 of the fifth lens 8 and the Abbe number VD6 of the sixth lens 9 is: |VD5-VD6|=42.6579, satisfying the relationship 35≤|VD5-VD6|≤43; The refractive index Nd5 of the fifth lens 8 is 1.4875, satisfying Nd5≤1.7; The Abbe number VD5 of the fifth lens 8 is 70.4196, satisfying VD5 ≥ 63; The refractive index Nd4 of the fourth lens 7 is 1.8348, and Nd4≥1.8.

[0051] The modulation transfer function (MTF) of this embodiment 1 is shown in FIG. Figure 3 As shown, with the distance from the center of the image field to the edge of the image field as the horizontal axis, it reflects the imaging quality of the edge of the lens. It can be seen that the imaging quality of this industrial lens from the center to the edge of the field of view is very uniform, that is, the entire image is very clear and the clarity of the image is guaranteed.

[0052] The MTF curve produced by the lines parallel to the diameter is called the sagittal curve, labeled S (Sagittal) curve, and the MTF curve produced by the lines parallel to the tangent is called the meridian curve, labeled T (Meridional) curve. Figure 3 There are multiple groups of MTF curves from the center of the image field to the edge of the image field, reflecting that this industrial lens has a high resolution.

[0053] The schematic diagram of field curvature / F-Tan(θ) distortion of the first embodiment is as follows: Figure 4 As shown, the left part is a schematic diagram of field curvature, where the horizontal axis represents the size of the field curvature in mm, and the vertical axis represents the image height. In the figure, the meridian field curvature value and the sagittal field curvature value are both controlled within ±0.1mm, indicating that the field curvature of the industrial lens has been well corrected; the right part is a schematic diagram of distortion, where the horizontal axis represents the distortion size in percentage, and the vertical axis represents the image height. It can be seen from the figure that the F-Tan (θ) distortion value is controlled within -1%, indicating that the distortion of the industrial lens has been well corrected.

[0054] The schematic diagram of vertical axis chromatic aberration in this embodiment 1 is as follows Figure 5 As shown, Figure 5 The horizontal axis represents the size of the vertical chromatic aberration, in um, and the vertical axis represents the image height, which represents the chromatic aberration of each wavelength at different image heights on the imaging surface. The horizontal axis represents the offset, in μm, and the vertical axis represents the object height, in mm. Figure 5 It can be seen that the vertical axis chromatic aberration between the shortest wavelength and the longest wavelength is controlled within ±2.5μm, indicating that the industrial lens can better correct the chromatic aberration of the edge field of view.

[0055] The axial aberration curve of this embodiment 1 is as follows Figure 6 As shown, it represents the aberration of each wavelength on the optical axis at the imaging plane, the horizontal axis represents the offset, the unit is mm, and the vertical axis represents the normalized pupil radius. Figure 6 It can be seen that the axial aberration of the shortest wavelength and the longest wavelength is controlled within ±0.06mm, indicating that the axial aberration of the industrial lens has been well corrected.

[0056] Depend on Figure 3-Figure 6 It can be seen that this industrial lens has low distortion, low chromatic aberration, high resolution, and can achieve better imaging effects.

[0057] Embodiment 2: This embodiment provides an industrial lens, such as Figure 7 As shown, in Example 2, the first lens 4 is a double convex positive lens, the second lens 5 is a meniscus positive lens convex to the object side, the third lens 6 is a double concave negative lens, the fourth lens 7 is a double convex positive lens, the fifth lens 8 is a meniscus positive lens convex to the image side, the sixth lens 9 is a double concave negative lens, the seventh lens 10 is a meniscus positive lens convex to the image side, and the eighth lens 11 is a double convex positive lens.

[0058] Based on the structure of the industrial lens provided in the above-mentioned embodiment 2, the industrial lens includes a biconvex positive lens, a meniscus positive lens convex to the object side, a biconcave negative lens, a biconvex positive lens, an aperture 2, a meniscus positive lens convex to the image side, a biconcave negative lens, a meniscus positive lens convex to the image side, a biconvex positive lens and an imaging surface 12, which are coaxially arranged in sequence. Table 3 shows various parameters of multiple lenses of the industrial lens.

[0059] Table 3: Combination Figure 1 and Figure 7 As shown, the object side surface S1 of the first lens 4, i.e., the biconvex positive lens, is a convex surface, and the image side surface S2 is a convex surface; The object side surface S3 of the second lens 5, i.e., the meniscus positive lens, is convex, and the image side surface S4 is concave; The object side surface S5 of the third lens element 6, i.e., the double concave negative lens, is concave, and the image side surface S6 is concave; The fourth lens element 7, i.e., a biconvex positive lens, has an object side surface S7 which is convex, and an image side surface S8 which is convex; The fifth lens 8, i.e., the meniscus positive lens, has an object side surface S10 which is a concave surface, and an image side surface S11 which is a convex surface; The object side surface S11 of the sixth lens element 9, i.e., the double concave negative lens, is a concave surface, and the image side surface S12 is a concave surface; The fifth lens 8 and the sixth lens 9 are cemented lenses and share S11, so S11 is convex relative to the fifth lens 8 and concave relative to the sixth lens 9; The object side surface S13 of the seventh lens element 10, i.e., the positive meniscus lens, is a concave surface, and the image side surface S14 is a convex surface; The object side surface S15 of the eighth lens 11, i.e., the biconvex positive lens, is a convex surface, and the image side surface S16 is a convex surface; IMA is the imaging surface.

[0060] In this embodiment 2, the parameters of the industrial lens are shown in Table 4.

[0061] Table 4: It can be seen from Table 4 above that in this embodiment 2, the relationship between the maximum field of view FOV of the industrial lens and the main ray incident angle CRA of the industrial lens is: FOV / CRA=4.7531, satisfying the relationship 4.3≤FOV / CRA≤5.6; The effective focal length f of the first lens group 1 u1 , the effective focal length f of the second lens group 3 u2 , the maximum image plane height IH: (f u1 +f u2 ) / IH=13.4891, satisfying the relationship 13≤(f u1 +f u2 ) / IH≤26; The relationship between the maximum field of view FOV, the head aperture size D, and the total optical length of the industrial lens is: TTLFOV / (D*TTL)=0.0278, satisfying the relationship FOV / (D*TTL)≥0.025; The focal length f of the first lens group 1 u1 , and the relationship between the effective focal length f of the entire industrial lens: |f u1 / f|=3.6332, satisfying the relationship |f u1 / f|≤8.1; The focal length f of the second lens group 3 u2 , and the relationship between the effective focal length f of the entire industrial lens: |f u2 / f|=1.0094, satisfying the relationship |f u2 / f|≥0.86; The relationship between the Abbe number VD5 of the fifth lens 8 and the Abbe number VD6 of the sixth lens 9 is: |VD5-VD6|=42.6579, satisfying the relationship 35≤|VD5-VD6|≤43; The refractive index Nd5 of the fifth lens 8 is 1.4875, satisfying Nd5≤1.7; The Abbe number VD5 of the fifth lens 8 is 70.4196, satisfying VD5 ≥ 63; The refractive index Nd4 of the fourth lens 7 is 1.8348, and Nd4≥1.8.

[0062] The modulation transfer function diagram of this embodiment 2 is as follows Figure 8 As shown, with the distance from the center of the image field to the edge of the image field as the horizontal axis, it reflects the imaging quality of the edge of the lens. It can be seen that the imaging quality of this industrial lens from the center to the edge of the field of view is very uniform, that is, the entire image is very clear and the clarity of the image is guaranteed.

[0063] The MTF curve produced by the line parallel to the diameter is called the sagittal curve, labeled S-curve, while the MTF curve produced by the line parallel to the tangent is called the meridian curve, labeled T-curve. Figure 8 There are multiple groups of MTF curves from the center of the image field to the edge of the image field, reflecting that this industrial lens has a high resolution.

[0064] The schematic diagram of field curvature / F-Tan(θ) distortion of the second embodiment is as follows: Fig. 9 As shown in the figure, the left part is a schematic diagram of field curvature, where the horizontal axis represents the field curvature size in mm, and the vertical axis represents the image height. In the figure, the meridian field curvature value and the sagittal field curvature value are both controlled within ±0.1mm, indicating that the field curvature of the industrial lens has been well corrected; the right part is a schematic diagram of distortion, where the horizontal axis represents the distortion size in percentage, and the vertical axis represents the image height. Fig. 9 It can be seen that the F-Tan(θ) distortion value is controlled within -1.2%, indicating that the distortion of the industrial lens has been well corrected.

[0065] The schematic diagram of vertical axis chromatic aberration in Example 2 is as follows Fig.10 As shown, Fig.10 The horizontal axis represents the size of the vertical chromatic aberration, in um, and the vertical axis represents the image height, which represents the chromatic aberration of each wavelength at different image heights on the imaging surface. The horizontal axis represents the offset, in μm, and the vertical axis represents the object height, in mm. Fig.10 It can be seen that the vertical axis chromatic aberration between the shortest wavelength and the longest wavelength is controlled within ±2μm, indicating that the industrial lens can better correct the chromatic aberration of the edge field of view.

[0066] The axial aberration curve of this embodiment 2 is as follows Fig.11 As shown, it represents the aberration of each wavelength on the optical axis at the imaging plane, the horizontal axis represents the offset, the unit is mm, and the vertical axis represents the normalized pupil radius. Fig.11It can be seen that the axial aberration of the shortest wavelength and the longest wavelength is controlled within ±0.05mm, indicating that the axial aberration of the industrial lens has been well corrected.

[0067] Depend on Figure 8-Figure 11 It can be seen that this industrial lens has low distortion, low chromatic aberration, high resolution, and can achieve better imaging effects.

[0068] Embodiment 3: This embodiment provides an industrial lens, such as Fig.12 As shown, in Example 3, the first lens 4 is a biconvex positive lens, the second lens 5 is a meniscus positive lens convex toward the object side, the third lens 6 is a biconcave negative lens, the fourth lens 7 is a biconvex positive lens, the fifth lens 8 is a biconvex positive lens, the sixth lens 9 is a biconcave negative lens, the seventh lens 10 is a meniscus positive lens convex toward the image side, and the eighth lens 11 is a biconvex positive lens.

[0069] Based on the structure of the industrial lens provided in the above-mentioned Example 3, the industrial lens includes a biconvex positive lens, a meniscus positive lens convex to the object side, a biconcave negative lens, a biconvex positive lens, an aperture 2, a biconvex positive lens, a biconcave negative lens, a meniscus positive lens convex to the image side, a biconvex positive lens and an imaging surface 12 arranged coaxially in sequence. Table 5 shows various parameters of multiple lenses of the industrial lens.

[0070] Table 5: Combination Figure 1 and Fig.12 As shown, the object side surface S1 of the first lens 4, i.e., the biconvex positive lens, is convex, and the image side surface S2 is convex; the object side surface S3 of the second lens 5, i.e., the meniscus positive lens, is convex, and the image side surface S4 is concave; The object side surface S5 of the third lens element 6, i.e., the double concave negative lens, is concave, and the image side surface S6 is concave; The fourth lens element 7, i.e., a biconvex positive lens, has an object side surface S7 which is convex, and an image side surface S8 which is convex; The object side surface S10 of the fifth lens element 8, i.e., the biconvex positive lens, is convex, and the image side surface S11 is convex; The object side surface S11 of the sixth lens element 9, i.e., the double concave negative lens, is a concave surface, and the image side surface S12 is a concave surface; The fifth lens 8 and the sixth lens 9 are cemented lenses and share S11, so S11 is convex relative to the fifth lens 8 and concave relative to the sixth lens 9; The object side surface S13 of the seventh lens element 10, i.e., the positive meniscus lens, is a concave surface, and the image side surface S14 is a convex surface; The object side surface S15 of the eighth lens 11, i.e., the biconvex positive lens, is a convex surface, and the image side surface S16 is a convex surface; IMA is the imaging surface.

[0071] In this embodiment 3, the parameters of the industrial lens are shown in Table 6.

[0072] Table 6: FOV 38.0000 CRA 6.9048 <![CDATA[f u1 ]]> 131.1678 <![CDATA[f u2 ]]> 14.1606 f 16.3764 D 24.9130 TTL 55.9775 IH 5.5970 <![CDATA[Nd4]]> 1.8348 <![CDATA[Nd5]]> 1.6180 <![CDATA[VD5]]> 63.4058 <![CDATA[VD6]]> 27.7617 It can be seen from Table 6 above that in this embodiment 3, the relationship between the maximum field of view FOV of the industrial lens and the main ray incident angle CRA of the industrial lens is: FOV / CRA=5.5034, satisfying the relationship 4.3≤FOV / CRA≤5.6; The effective focal length f of the first lens group 1 u1 , the effective focal length f of the second lens group 3 u2 , the maximum image plane height IH: (f u1 +f u2 ) / IH=25.9654, satisfying the relationship 13≤(f u1 +f u2 ) / IH≤26; The relationship between the maximum field of view FOV, the head aperture size D, and the total optical length of the industrial lens is: TTLFOV / (D*TTL)=0.0272, satisfying the relationship FOV / (D*TTL)≥0.025; The focal length f of the first lens group 1 u1 , and the relationship between the effective focal length f of the entire industrial lens: |f u1 / f|=8.0096, satisfying the relationship |f u1 / f|≤8.1; The focal length f of the second lens group 3 u2 , and the relationship between the effective focal length f of the entire industrial lens: |f u2 / f|=0.8647, satisfying the relationship |f u2 / f|≥0.86; The relationship between the Abbe number VD5 of the fifth lens 8 and the Abbe number VD6 of the sixth lens 9 is: |VD5-VD6|=35.6441, satisfying the relationship 35≤|VD5-VD6|≤43; The refractive index Nd5 of the fifth lens 8 is 1.6180, satisfying Nd5≤1.7; The Abbe number VD5 of the fifth lens 8 is 63.4058, satisfying VD5 ≥ 63; The refractive index Nd4 of the fourth lens 7 is 1.8348, and Nd4≥1.8.

[0073] The modulation transfer function diagram of this embodiment 3 is as follows Fig.13As shown, with the distance from the center of the image field to the edge of the image field as the horizontal axis, it reflects the imaging quality of the edge of the lens. It can be seen that the imaging quality of this industrial lens from the center to the edge of the field of view is very uniform, that is, the entire image is very clear and the clarity of the image is guaranteed.

[0074] The MTF curve produced by the line parallel to the diameter is called the sagittal curve, labeled S-curve, while the MTF curve produced by the line parallel to the tangent is called the meridian curve, labeled T-curve. Fig.13 There are multiple groups of MTF curves from the center of the image field to the edge of the image field, reflecting that this industrial lens has a high resolution.

[0075] The schematic diagram of field curvature / F-Tan(θ) distortion of the third embodiment is as follows: Fig.14 As shown in the figure, the left part is a schematic diagram of field curvature, where the horizontal axis represents the field curvature size in mm, and the vertical axis represents the image height. In the figure, the meridian field curvature value and the sagittal field curvature value are both controlled within ±0.1mm, indicating that the field curvature of the industrial lens has been well corrected; the right part is a schematic diagram of distortion, where the horizontal axis represents the distortion size in percentage, and the vertical axis represents the image height. Fig.14 It can be seen that the F-Tan(θ) distortion value is controlled within -1%, indicating that the distortion of the industrial lens has been well corrected.

[0076] The schematic diagram of vertical axis chromatic aberration in Example 3 is as follows Fig.15 As shown, Fig.15 The horizontal axis represents the size of the vertical chromatic aberration, in um, and the vertical axis represents the image height, which represents the chromatic aberration of each wavelength at different image heights on the imaging surface. The horizontal axis represents the offset, in μm, and the vertical axis represents the object height, in mm. Fig.15 It can be seen that the vertical axis chromatic aberration between the shortest wavelength and the longest wavelength is controlled within ±1.5μm, indicating that the industrial lens can better correct the chromatic aberration of the edge field of view.

[0077] The axial aberration curve of this embodiment 3 is as follows Fig.16 As shown, it represents the aberration of each wavelength on the optical axis at the imaging plane, the horizontal axis represents the offset, the unit is mm, and the vertical axis represents the normalized pupil radius. Fig.16 It can be seen that the axial aberration of the shortest wavelength and the longest wavelength is controlled within ±0.07mm, indicating that the axial aberration of the industrial lens has been well corrected.

[0078] Depend on Figure 13-Figure 16 It can be seen that this industrial lens has low distortion, low chromatic aberration, high resolution, and can achieve better imaging effects.

[0079] The present application also proposes an optical device, which includes the industrial lens in any of the aforementioned embodiments. The specific structure of the industrial lens refers to any of the aforementioned embodiments. Since the optical device proposed in the present application can apply all the technical solutions in all the aforementioned embodiments, it at least has all the beneficial effects brought by the aforementioned technical solutions, which will not be described one by one here.

[0080] The above are only optional embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. An industrial lens, characterized in that: The invention comprises a first lens group (1), an aperture (2) and a second lens group (3) which are coaxially arranged in sequence, wherein the first lens group (1) comprises a first lens (4), a second lens (5), a third lens (6) and a fourth lens (7) which are arranged in sequence from the object side to the image side along the optical axis, wherein the first lens (4), the second lens (5) and the fourth lens (7) have positive focal power, and the third lens (6) has negative focal power; The second lens group (3) comprises a fifth lens (8), a sixth lens (9), a seventh lens (10) and an eighth lens (11) which are arranged in sequence from the object side to the image side along the optical axis, the fifth lens (8), the seventh lens (10) and the eighth lens (11) having positive optical power, and the sixth lens (9) having negative optical power; Industrial lenses satisfy the following relationship: 3≤FOV / CRA≤5.6; 13≤(f u1 +f u2 ) / IH≤26; FOV / (D*TTL)≥0.025; Wherein, FOV is the maximum field of view angle of the industrial lens, CRA is the incident angle of the main light of the industrial lens, and f u1 is the effective focal length of the first lens group (1) in the industrial lens, f u2 is the effective focal length of the second lens group (3) in the industrial lens, IH is the maximum image plane height of the industrial lens, D is the head aperture size of the industrial lens, and TTL is the total optical length of the industrial lens.

2. An industrial lens according to claim 1, characterized in that: The first lens (4) and the second lens (5) are positive meniscus lenses convex toward the object side, the third lens (6) is a double concave negative lens, the fourth lens (7) is a double convex positive lens, the fifth lens (8) is a plano-convex positive lens, the sixth lens (9) is a double concave negative lens, the seventh lens (10) is a positive meniscus lens convex toward the image side, and the eighth lens (11) is a double convex positive lens.

3. An industrial lens according to claim 1, characterized in that: The first lens (4) is a biconvex positive lens, the second lens (5) is a meniscus positive lens convex toward the object side, the third lens (6) is a biconcave negative lens, the fourth lens (7) is a biconvex positive lens, the fifth lens (8) is a meniscus positive lens convex toward the image side, the sixth lens (9) is a biconcave negative lens, the seventh lens (10) is a meniscus positive lens convex toward the image side, and the eighth lens (11) is a biconvex positive lens.

4. The industrial lens according to claim 1, characterized in that: The first lens (4) is a biconvex positive lens, the second lens (5) is a meniscus positive lens convex toward the object side, the third lens (6) is a biconcave negative lens, the fourth lens (7) is a biconvex positive lens, the fifth lens (8) is a biconvex positive lens, the sixth lens (9) is a biconcave negative lens, the seventh lens (10) is a meniscus positive lens convex toward the image side, and the eighth lens (11) is a biconvex positive lens.

5. The industrial lens according to claim 1, characterized in that: The industrial lens also satisfies the following relationship: |f u1 / f|≤8.1; |f u2 / f|≥0.86; Wherein f is the effective focal length of the industrial lens.

6. An industrial lens according to any one of claim 1, characterized in that: The fifth lens (8) and the sixth lens (9) are double-cemented lenses and are glass lenses.

7. An industrial lens according to claim 6, characterized in that: The industrial lens also satisfies the following relationship: 35≤|VD5-VD6|≤43, Wherein VD5 is the Abbe number of the fifth lens (8), and VD6 is the Abbe number of the sixth lens (9).

8. The industrial lens according to claim 1, characterized in that: The industrial lens also satisfies the following relationship: Nd4≥1.8, Wherein Nd4 is the refractive index of the lens material of the fourth lens (7) in the industrial lens at the Fraunhofer spectrum line.

9. An industrial lens according to claim 6, characterized in that: The industrial lens also satisfies the following relationship: Nd5≤1.7; VD5≥63; Wherein Nd5 is the refractive index of the lens material of the fifth lens (8) in the industrial lens at the Fraunhofer spectrum line, and VD5 is the Abbe number of the fifth lens (8).

10. An optical device, characterized in that: Comprising the industrial lens as described in any one of claims 1-9.

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