Industrial lens and machine vision system

Abstract

The embodiment of the invention provides an industrial lens and a machine vision system. The industrial lens sequentially comprises a first lens group, a diaphragm and a second lens group along an optical axis. The first lens group comprises a first lens, a second lens, a third lens and a fourth lens, the first lens is a biconvex positive lens, the second lens is a meniscus negative lens, the third lens is a biconcave negative lens, and the fourth lens is a biconvex positive lens; the first lens is glued with the second lens, and the third lens is glued with the fourth lens; the second lens group comprises a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens and a tenth lens; the fifth lens is a biconcave negative lens, the sixth lens is a biconvex positive lens, the seventh lens is a biconvex positive lens, the eighth lens is a biconvex positive lens, the ninth lens is a meniscus negative lens, and the tenth lens is a biconcave negative lens; the fifth lens and the sixth lens are glued, and the eighth lens and the ninth lens are glued; the first lens to the tenth lens are all spherical lenses and are made of optical glass materials.

Description

Technical Field

[0001] This application relates to the field of optical imaging technology, specifically to an industrial lens suitable for machine vision inspection, and a machine vision system including the industrial lens. Background Technology

[0002] Industrial lenses are core components of machine vision systems, and their imaging quality directly determines the accuracy and reliability of inspection. In applications such as high-precision dimensional measurement and appearance defect inspection (AOI), lenses are typically required to have a large image field (to match high-pixel sensors), high resolution (especially maintaining a high modulation transfer function (MTF) value at high spatial frequencies), and extremely low distortion, while also taking into account structural compactness and manufacturing cost.

[0003] Currently, industrial lenses on the market suitable for 20-megapixel sensors (corresponding to approximately 1.2-inch target surfaces) generally face technical bottlenecks when pursuing high resolution (e.g., 200 lp / mm): First, the MTF value drops sharply at the edge of the image field, often falling below 0.1, resulting in insufficient image edge sharpness and affecting the accuracy of full-field measurement. Second, optical distortion is difficult to control at a low level (usually greater than 0.5%), which is unacceptable for applications with extremely high geometric accuracy requirements, such as dimensional measurement. To improve these performance issues, traditional design approaches often introduce aspherical lenses or use special optical materials such as anomalous dispersion. While this can improve image quality to some extent, the processing and testing costs of aspherical lenses are high, and special materials significantly increase raw material costs, raising the overall cost of the lens and hindering its large-scale industrial application.

[0004] Therefore, how to design an industrial lens that combines a large target area (compatible with 1.2-inch sensors), high edge MTF, low distortion, compact structure, and controllable cost by using only conventional spherical glass lenses through innovative optical architecture and power distribution has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this application is to provide a new technical solution for an industrial lens and a machine vision system, wherein the industrial lens can achieve a good balance of large target area, high resolution, low distortion and miniaturization under the condition of using a global surface glass lens.

[0006] In a first aspect, embodiments of this application provide an industrial lens, which includes, along the optical axis, a first lens group, an aperture stop, and a second lens group in sequence. The first lens group includes a first lens, a second lens, a third lens, and a fourth lens in sequence. The first lens is a biconvex positive lens, the second lens is a meniscus negative lens, the third lens is a biconcave negative lens, and the fourth lens is a biconvex positive lens. The first lens is cemented to the second lens, and the third lens is cemented to the fourth lens. The second lens group sequentially includes a fifth lens, a sixth lens, a seventh lens, an eighth lens, a ninth lens, and a tenth lens. The fifth lens is a biconcave negative lens, the sixth lens is a biconvex positive lens, the seventh lens is a biconvex positive lens, the eighth lens is a biconvex positive lens, the ninth lens is a meniscus negative lens, and the tenth lens is a biconcave negative lens. The fifth lens is cemented with the sixth lens, and the eighth lens is cemented with the ninth lens. All of the first to the tenth lenses are spherical lenses and are made of optical glass.

[0007] Optionally, the working distance WD supported by the industrial lens and the focal length f of the industrial lens satisfy the following condition: 2.8≤WD / f≤17.1; wherein, the working distance WD is defined as the axial distance from the object-side surface of the first lens of the industrial lens to the object plane where the observed object is located, and the working distance WD is 100mm~600mm; The aperture value F of the industrial lens is 2.8 ≤ F ≤ 16.

[0008] Optionally, the concave surface of the second lens faces the first lens, and the concave surface of the ninth lens faces the eighth lens.

[0009] Optionally, the industrial lens is composed of ten lenses, from the first lens to the tenth lens, wherein the first lens is located on the object side and the tenth lens is located on the image side.

[0010] Optionally, the focal length of the industrial lens is f, and the effective focal length of the first lens is F1, satisfying: 3≤F1 / f≤4; The effective focal length of the second lens is F2, and satisfies: -0.4≤F1 / F2≤-0.2; The effective focal length of the third lens is F3, and the effective focal length of the fourth lens is F4, and F3 and F4 satisfy: -23≤F3 / F4≤-17; The effective focal length of the fifth lens is F5, and the effective focal length of the sixth lens is F6, and F5 and F6 satisfy: -0.7≤F5 / F6≤-0.2; The effective focal length of the seventh lens is F7, and satisfies: 0.5≤F7 / f≤1.5; The effective focal length of the eighth lens is F8, and the effective focal length of the ninth lens is F9, and F8 and F9 satisfy: -1≤F8 / F9≤-0.4; The effective focal length of the tenth lens is F10, and satisfies: -1≤F10 / f≤-0.3.

[0011] Optionally, the total optical length (TTL) of the industrial lens satisfies: TTL≤60mm; The half-image height Y of the industrial lens satisfies: Y≥9.6mm; The focal length f of the industrial lens is 35mm.

[0012] Optionally, the Abbe number of the first lens is V1, and the Abbe number of the second lens is V2, and the following conditions are met: 10≤|V1-V2|≤20.

[0013] Optionally, the radius of curvature of the surface of the seventh lens near the eighth lens is R72, and the radius of curvature of the surface of the eighth lens near the seventh lens is R81, satisfying: 1.3≤|R72 / R81|≤1.4, and the air gap d78 between the seventh lens and the eighth lens satisfies: 0.1≤d78 / f≤0.15, where f is the focal length of the industrial lens.

[0014] Optionally, the air gap between the aperture and the fourth lens is Ds, and the center thickness of the fifth lens on the optical axis is Ct5, satisfying: 0.5≤Ds / Ct5≤0.6.

[0015] Optionally, the distance between the tenth lens and the image side on the optical axis is the back clipping BFL, and the focal length of the industrial lens is f, satisfying: 0.25≤BFL / f≤0.3.

[0016] Optionally, within the visible light spectrum, the modulation transfer function (MTF) value of the industrial lens at a spatial frequency of 200 lp / mm is not less than 0.3; and the absolute value of the maximum optical distortion of the industrial lens is not greater than 0.5%.

[0017] Secondly, embodiments of this application provide a machine vision system, the machine vision system comprising: Industrial lenses as described in the first aspect; and An image sensor is disposed on the image side of the industrial lens and is used to receive the image formed by the industrial lens.

[0018] The beneficial effects of this application are as follows: The industrial lens provided in this application employs a ten-element, four-group global surface glass lens structure with specific optical power and bonding relationships. This structure enables the coordinated correction of various aberrations without relying on aspherical or special dispersive materials. This optical design effectively improves the problems of low edge field-of-view modulation transfer function (MTF) values ​​(typically below 0.1) and high optical distortion (typically above 0.5%) at high spatial frequencies such as 200 lp / mm. As a result, it achieves excellent optical performance with high-resolution imaging and low distortion while adapting to large-area sensors (such as 1.2 inches), and significantly reduces the manufacturing cost and processing difficulty of industrial lenses.

[0019] Other features and advantages of this specification will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0020] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of this specification and, together with their description, serve to explain the principles of this specification.

[0021] Figure 1 One of the schematic diagrams of the optical structure and optical path of an industrial lens provided in the embodiments of this application; Figure 2 One of the MTF diagrams of an industrial lens provided in the embodiments of this application; Figure 3 One of the field curvature and distortion diagrams of an industrial lens provided in the embodiments of this application; Figure 4 A second schematic diagram of the optical structure and optical path of an industrial lens provided in an embodiment of this application; Figure 5 The second MTF diagram of an industrial lens provided in the embodiments of this application; Figure 6 A second field curvature and distortion diagram of an industrial lens provided in an embodiment of this application; Figure 7 The third schematic diagram of the optical structure and optical path of an industrial lens provided in the embodiments of this application; Figure 8 The third MTF diagram of an industrial lens provided in the embodiments of this application; Figure 9 The third example of field curvature and distortion diagrams of an industrial lens provided in this application embodiment; Figure 10 Fourth schematic diagram of the optical structure and optical path of an industrial lens provided in the embodiments of this application; Figure 11 The fourth MTF diagram of an industrial lens provided in the embodiments of this application; Figure 12Fourth of the field curvature and distortion diagrams of an industrial lens provided in the embodiments of this application; Figure 13 The relative illumination diagram of the industrial lens provided in the embodiments of this application.

[0022] Explanation of reference numerals in the attached figures: 1. First lens; 2. Second lens; 3. Third lens; 4. Fourth lens; 5. Fifth lens; 6. Sixth lens; 7. Seventh lens; 8. Eighth lens; 9. Ninth lens; 10. Tenth lens; 11. Aperture stop. Detailed Implementation

[0023] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0024] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0025] Technologies and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such technologies and equipment should be considered part of the specification.

[0026] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0027] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0028] The industrial lens and machine vision system provided in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0029] According to one embodiment of this application, an industrial lens is provided, see [link to relevant documentation]. Figure 1The system comprises, along its optical axis, a first lens group, an aperture stop 11, and a second lens group. The first lens group comprises, in sequence, a first lens 1, a second lens 2, a third lens 3, and a fourth lens 4. The first lens 1 is a biconvex positive lens, the second lens 2 is a meniscus negative lens, the third lens 3 is a biconcave negative lens, and the fourth lens 4 is a biconvex positive lens. The first lens 1 and the second lens 2 are cemented together, and the third lens 3 and the fourth lens 4 are cemented together. The second lens group comprises, in sequence, a fifth lens 5, a sixth lens 6, a seventh lens 7, an eighth lens 8, a ninth lens 9, and a tenth lens 10. The fifth lens 5 is a biconcave negative lens, the sixth lens 6 is a biconvex positive lens, the seventh lens 7 is a biconvex positive lens, the eighth lens 8 is a biconvex positive lens, the ninth lens 9 is a meniscus negative lens, and the tenth lens 10 is a biconcave negative lens. The fifth lens 5 and the sixth lens 6 are cemented together, and the eighth lens 8 and the ninth lens 9 are cemented together. All lenses from the first lens 1 to the tenth lens 10 are spherical lenses and are made of optical glass.

[0030] This application provides an industrial lens designed for high-precision inspection needs in fields such as machine vision and factory automation. The industrial lens integrates a long focal length, large target area, low distortion, high resolution, and a wide range of adjustable working distances, providing stable and clear high-quality images for applications such as precision dimensional measurement, semiconductor chip and component appearance defect detection, and electronic product assembly positioning and quality inspection. By employing an all-glass spherical lens optical architecture, the industrial lens achieves excellent optical performance while significantly reducing manufacturing costs and process complexity, providing a high-performance, highly adaptable, and cost-effective optical imaging solution for industrial inspection.

[0031] The specific optical structure, design principle, and technical effects of the industrial lens provided in the embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0032] The industrial lens provided in this application embodiment adopts an optical configuration in which a first lens group, an aperture stop 11, and a second lens group are arranged sequentially along the optical axis from the object side to the image side. See [link to application]. Figure 1 This optical architecture, by placing the aperture stop 11 in the middle of the entire industrial lens, divides the entire lens system into front and rear groups. This facilitates the rational distribution of the system's optical power and enables effective control and coordinated correction of various aberrations (especially astigmatism, field curvature, and distortion), thus laying the structural foundation for achieving optical performance with a large target area, high resolution, and low distortion.

[0033] In the industrial lenses involved in this application, the optical design is based on the modeling and optimization of the backlight path from the image side to the object side. See [link / reference] Figure 1The actual propagation of light used for imaging in the industrial lens follows this sequence: light entering from the image side first passes sequentially through the tenth lens 10, the ninth lens 9, the eighth lens 8, the seventh lens 7, the sixth lens 6, and the fifth lens 5 in the second lens group. It then passes through the aperture 11 located in the center of the industrial lens, and subsequently enters the first lens group, passing sequentially through the fourth lens 4, the third lens 3, the second lens 2, and the first lens 1. Finally, the light converges and exits to the object side, forming a clear image on the image plane. This specific optical path layout is the core design adopted in this application to achieve effective correction of large target aberrations (especially chromatic aberration, astigmatism, and distortion) and optimize overall optical performance.

[0034] The first lens group (also known as the front group) is located between the object side and the aperture stop 11 in the optical path, and it is designed to include four lenses with specific optical powers. The light propagation sequence, specific structure, and optical function of the first lens group are as follows: After passing through the aperture stop 11, light first enters the fourth lens 4. The fourth lens 4 is a biconvex positive lens, and it is cemented together with the immediately following third lens 3 to form a second cemented lens group. This second cemented lens group plays an important role in correcting chromatic aberration (especially axial chromatic aberration). It effectively compensates for the focus shift of light of different wavelengths through the combination of positive and negative lens materials, and at the same time provides a key role in controlling the optical power of the second lens group and balancing the curvature of the image plane (field curvature).

[0035] Subsequently, the light passes through the third lens 3. The third lens 3 is a biconcave negative lens, whose negative optical power helps to moderately diverge the light to correct astigmatism and further optimize the optical path.

[0036] Next, the light reaches the second lens 2. The second lens 2 is a meniscus negative lens, see [link / reference]. Figure 1 As shown, its concave surface faces the object side (i.e., towards the first lens 1). This lens is designed for fine adjustment of the light angle, correction of residual aberrations, and preparation for final light convergence.

[0037] Finally, the light rays exit through the first lens 1 and reach the object side. The first lens 1 is a biconvex positive lens. As the optical element closest to the object side in the first lens group, its strong positive optical power undertakes the main task of light convergence, which is the basis for realizing the long focal length characteristics of industrial lenses, and performs the final correction of spherical aberration.

[0038] It should be noted that the first lens 1 and the second lens 2 are cemented together to form a first cemented lens group. This first cemented lens group works in conjunction with the aforementioned second cemented lens group (composed of the fourth lens 4 and the third lens 3 cemented together) to form a multi-layered achromatic and aberration balancing architecture within the first lens group (front group), laying a key foundation for the entire industrial lens to achieve excellent performance of large target area, high resolution and low distortion.

[0039] The second lens group (also known as the rear group) is located between the image side and the aperture stop 11 in the optical path. It contains six lenses with specific optical powers, and their light propagation sequence, specific structure, and optical function are as follows: Light enters the tenth lens 10 from the image side. The tenth lens 10 is a biconcave negative lens, whose negative optical power serves as the starting point of the rear group, initially collecting and moderately diverging the light from the image side. The introduction of this tenth lens 10 provides a crucial negative optical power contribution to the entire industrial lens. In conjunction with the positive optical power lenses in the lens, it effectively balances the optical power distribution of the system, which is one of the key designs for correcting image plane curvature (field curvature), and also helps control the back intercept.

[0040] Subsequently, the light reaches the ninth lens 9. The ninth lens 9 is a meniscus negative lens, with its concave surface facing the object side (i.e., its concave surface facing the eighth lens 8), and is cemented with the eighth lens 8 to form a fourth cemented group. This fourth cemented group utilizes the combination of a negative lens and a positive lens to effectively correct chromatic aberration (magnification chromatic aberration) and compensate for and balance some of the aberrations introduced by the tenth lens 10, thereby optimizing the uniformity of image illumination.

[0041] Next, the light passes through the eighth lens 8 and the seventh lens 7. Both the eighth lens 8 and the seventh lens 7 are biconvex positive lenses. These two adjacent and spaced-apart positive lenses form a lens combination with strong positive optical power, mainly responsible for converging the light and guiding it to the aperture stop 11. A specific air gap is maintained between them. This optical design plays a key role in correcting astigmatism and spherical aberration, and through the optimized combination of its curvature and spacing, it provides core support for achieving high resolution in industrial lenses.

[0042] Subsequently, the light reaches the sixth lens 6 and the fifth lens 5. The sixth lens 6 is a biconvex positive lens, and the fifth lens 5 is a biconcave negative lens; the two are cemented together to form a third cemented lens group. This third cemented lens group is located adjacent to the incident side of the aperture stop 11 and is a crucial achromatic and aberration balancing hub in the second lens group (rear group). It can efficiently correct axial chromatic aberration and higher-order aberrations, and perform final shaping of the beam after passing through the front lens, ensuring that the beam smoothly enters the aperture stop 11 with optimal aperture and angle, thereby creating favorable conditions for further aberration correction in the first lens group (front group).

[0043] In the industrial lens provided in this application, the first lens 1 to the tenth lens 10 are all spherical lenses and are all made of optical glass material. This technical feature clarifies the core choices of this application in terms of lens surface shape and material, specifically reflected in the following two aspects: Firstly, the optical surfaces of all ten lenses in the industrial lens are spherical. Compared to aspherical lenses, spherical lenses have significant advantages such as mature processing technology, unified testing standards, and controllable manufacturing costs. They are particularly suitable for industrial lenses that require large-scale, highly consistent production, which helps ensure product stability and economy.

[0044] Secondly, all ten lenses in the industrial lens use conventional optical glass, i.e., no special types of glass materials such as those with anomalous dispersion are used. This choice fundamentally avoids the cost increase problem caused by introducing expensive special materials in pursuit of high performance. This application achieves systematic correction of various aberrations such as chromatic aberration, astigmatism, field curvature, and distortion within an all-conventional glass system through innovative power distribution, multiple cemented structures (such as cemented combinations of the first lens 1 and the second lens 2, the third lens 3 and the fourth lens 4, the fifth lens 5 and the sixth lens 6, and the eighth lens 8 and the ninth lens 9), and precise aberration correction relationships. This demonstrates that the breakthrough of this application lies in the innovation of optical architecture and design methods, rather than relying on high-cost materials, thus achieving excellent optical performance (e.g., MTF ≥ 0.3 and optical distortion ≤ 0.5% at a spatial frequency of 200 lp / mm) while possessing outstanding cost advantages and industrial applicability.

[0045] In this application, the combined focal length of the first lens group (front group) is defined as Fa, and the combined focal length of the second lens group (rear group) is defined as Fb, and the relationship must be satisfied: 0.5≤Fa / Fb≤1.

[0046] In one specific embodiment of this application, the combined focal length Fa of the first lens group is 45.3mm, and the combined focal length Fb of the second lens group is 59.2mm, then Fa / Fb is 0.765.

[0047] In this application, the constraint of Fa / Fb being between 0.5 and 1 specifies the optical power ratio between the first lens group (front group) and the second lens group (rear group). This is one of the key design constraints for achieving miniaturization, wide working distance, and excellent imaging quality of the entire industrial lens. Its specific effects are reflected in the following aspects: (1) Constrain the size of industrial lenses to support their long working distance; By controlling the lower limit of the Fa / Fb ratio to 0.5, sufficient optical power is ensured for the first lens group (front group). This allows industrial lenses to achieve a wide working distance range of 100mm to 600mm without excessively relying on extending the total optical length (TTL) to reach the target focal length, thereby keeping the total optical length of the industrial lens within 60mm and achieving a compact optical structure.

[0048] (2) Collaborative aberration correction to optimize full-field performance; This ratio works in conjunction with multiple cemented structures within the industrial lens (such as the first lens 1 and the second lens 2, the third lens 3 and the fourth lens 4, the fifth lens 5 and the sixth lens, and the eighth and ninth lens cemented groups) to lay the foundation for achieving low distortion and high resolution, wherein: The first lens group (front group) (primarily positive optical power) and the second lens group (rear group) (containing a combination of positive and negative lenses) share the optical power in a reasonable ratio, avoiding excessive concentration of aberration correction burden on one group. Combined with the configuration of negative lenses (such as the tenth lens) in the rear group, field curvature and astigmatism are systematically compensated, promoting image plane flatness.

[0049] This ratio helps maintain a balanced propagation of light before and after the aperture 11. Combined with the spacing design between the aperture 11 and adjacent lenses (e.g., a specific ratio of the air gap between the aperture 11 and the fourth lens 4 to the center thickness of the fifth lens 5), the beam aperture fill factor is optimized, thus creating conditions for obtaining a uniform illumination distribution across the entire large target surface (adapted to a 1.2-inch sensor) and maintaining high-contrast imaging at high spatial frequencies (e.g., 200 lp / mm).

[0050] (3) Ensure stable optical performance; Setting the upper limit of the ratio Fa / Fb to 1 effectively prevents a significant increase in the difficulty of correcting aberrations such as spherical aberration and coma that may be caused by excessive optical focal length in the first lens group (front group). This constraint ensures stable performance of the optical design within a specified wide working distance range, thereby reliably achieving the design goals of low distortion (≤0.5%) and high resolution (MTF@200 lp / mm≥0.3) across the entire range.

[0051] The choice of material for the global surface glass reflects the balance between performance and cost in this application. The optimized front-to-rear focal length ratio (Fa / Fb) of 0.765 is the core optical design foundation for achieving synergistic optimization of miniaturization, wide working distance, and superior image quality. Together, these two elements constitute the innovation of this application, distinguishing it from traditional designs that rely on special materials or lead to complex optical structures.

[0052] This application embodiment, through the aforementioned specific optical architecture, precise arrangement of ten lenses, and collaborative design of four sets of cemented doublet lenses, and by satisfying the key optical power ratio condition of 0.5≤Fa / Fb≤1 between the first and second lens groups, jointly constructs a highly efficient, collaborative, and aberration-balanced optical system. The optical design scheme provided by this application fully leverages the optical power distribution of the front and rear lens groups and the aberration-correcting advantages of the cemented doublet lens groups. Based entirely on conventional spherical glass materials, it effectively overcomes the aberration challenges under large target surfaces and long working distances. Ultimately, under the premise of a compact structure (total optical length ≤60mm), it simultaneously achieves excellent comprehensive performance in high resolution (MTF≥0.3 at 200 lp / mm), low distortion (≤0.5%), and wide working distance (100mm~600mm) focusing, providing a cost-effective and highly adaptable optical imaging solution for the industrial inspection field.

[0053] It should be noted that the ratio Fa / Fb of the combined focal length Fa of the first lens group and the combined focal length Fb of the second lens group can be selected and optimized according to specific design goals, provided that the relationship 0.5 ≤ Fa / Fb ≤ 1 is met, but it needs to be within the range of 0.5 to 1. Different ratios correspond to different tendencies in the distribution of optical power between the two lens groups, which can have a systematic impact on the total optical length (TTL), aberration balance characteristics, and working distance adaptability of the entire industrial lens. Those skilled in the art can make reasonable selections and adjustments within this range according to actual performance priorities (e.g., more emphasis on structural compactness, or more emphasis on depth correction of specific aberrations). These design variations based on the core relationship defined in this application all fall within the protection scope of this application.

[0054] In some examples of this application, the working distance WD supported by the industrial lens and the focal length f of the industrial lens satisfy: 2.8≤WD / f≤17.1; wherein, the working distance WD is defined as the axial distance from the object-side surface of the first lens 1 of the industrial lens to the object plane where the observed object is located, and the working distance WD is 100mm~600mm; the aperture value F of the industrial lens is 2.8≤F≤16.

[0055] With a working distance of 100mm to 600mm, this industrial lens can adapt to various industrial inspection scenarios. A closer working distance (e.g., 100mm) is suitable for high-magnification, high-precision dimensional measurement of small parts or localized features. A longer working distance (e.g., 600mm) facilitates overall appearance monitoring and positioning of larger workpieces or production units. This focusing range significantly enhances the adaptability and versatility of the industrial lens in factory automation lines.

[0056] Maintaining a WD / f ratio between 2.8 and 17.1 is crucial for achieving stable optical performance in optical design. This ratio matches the specific optical architecture used in industrial lenses (e.g., the focal length ratio of the first and second lens groups must satisfy 0.5 ≤ Fa / Fb ≤ 1). It ensures that the lens's main aberrations (such as spherical aberration, field curvature, and distortion) are consistently and effectively controlled when the working distance WD varies over a wide range.

[0057] Using a large aperture of F2.8 helps increase the amount of light entering the image under low-light conditions, thereby effectively improving the overall brightness and signal-to-noise ratio of the image. Stopping down the aperture to F16 can significantly expand the depth of field, which is particularly advantageous for applications where the surface of the object being inspected has height variations or where clear imaging is required across the entire field of view.

[0058] The wide working distance (100mm~600mm) and its specific ratio to the focal length f (2.8≤WD / f≤17.1), along with the variable aperture feature, together constitute the comprehensive capability of the industrial lens of this application to meet the needs of complex industrial environments. This enables the lens to not only perform excellently in its core optical performance, but also to possess outstanding scene adaptability and imaging stability in practical applications.

[0059] See some examples in this application. Figure 1 The concave surface of the second lens 2 faces the first lens 1, and the concave surface of the ninth lens 9 faces the eighth lens 8.

[0060] In this example of the application, see Figure 1 The concave surface of the second lens 2 faces the first lens 1, and the concave surface of the ninth lens 9 faces the eighth lens 8. This structural feature is one of the key design features for achieving specific aberration correction in the lens, and its specific function is described below.

[0061] See Figure 1 The second lens 2 is a meniscus negative lens, with its concave surface oriented towards the first lens 1 (i.e., towards the object side). In the first cemented lens group formed by cementing the first lens 1 (a biconvex positive lens) and the second lens 2, this orientation causes the cemented surface (i.e., the concave surface of the second lens 2) to form a bonding surface with negative optical power. This design effectively utilizes the difference in Abbe number between the materials of the first lens 1 and the second lens 2 to form a highly efficient achromatic unit, primarily correcting axial chromatic aberration. Simultaneously, the meniscus structure and its orientation facilitate smoothing the refraction of light within the first lens group (front group), positively impacting the control of field curvature and spherical aberration.

[0062] Please continue reading Figure 1The ninth lens 9 is a meniscus negative lens, with its concave surface facing the eighth lens 8 (i.e., towards the object side). In the fourth cemented lens group formed by cementing the eighth lens 8 (a biconvex positive lens) and the ninth lens 9, this orientation ensures that the cemented surface (i.e., the concave surface of the ninth lens 9) also contributes negative optical power. This fourth cemented lens group is mainly used to correct chromatic aberration (magnification chromatic aberration). Simultaneously, the concave surface of the ninth lens 9, in conjunction with the negative optical power surface of the subsequent tenth lens 10 (a biconcave negative lens), forms a "negative-negative" relay structure in the optical path. This optical combination plays a crucial role in controlling astigmatism and further suppressing optical distortion (especially distortion at the edge of the field of view), helping to make the distortion distribution more symmetrical, thereby ensuring an extremely low distortion level of less than 0.5% across the entire image field.

[0063] See some examples in this application. Figure 1 The industrial lens is composed of ten lenses, from the first lens 1 to the tenth lens 10, wherein the first lens 1 is located on the object side and the tenth lens 10 is located on the image side.

[0064] In this example of the application, see Figure 1 The industrial lens design consists of ten lenses, from the first lens 1 to the tenth lens 10. The following is a description of this example: All ten lenses have spherical optical surfaces. Compared to aspherical lenses, spherical lenses have more mature and standardized processing and testing technologies, which not only helps ensure the consistency of lens performance in mass production, but also significantly reduces the overall cost of manufacturing and quality control.

[0065] In the industrial lens of this application, all lenses are made of conventional optical glass materials, avoiding the use of expensive special dispersive glass (such as fluorite) or non-glass materials. This example achieves excellent aberration correction effects while keeping costs under control by systematically combining conventional glasses with different refractive indices and dispersion characteristics in the design and by using a specially designed optical architecture.

[0066] Specifically, according to the optical design provided in this application, the refractive index (Nd) of the optical glass material mainly covers the range of approximately 1.49 to 1.83, and the Abbe number (Vd) mainly covers the range of approximately 27.5 to 81.6. By purposefully pairing and combining glasses with significant differences in Abbe number (e.g., ΔVd ≥ 15) in multiple sets of cemented doublets (such as the first cemented lens group composed of the first lens and the second lens), a highly efficient achromatic unit is constructed. Simultaneously, the rational use of conventional glass with a high refractive index in the optical path helps to reduce the radius of curvature of the lens while achieving the required optical power, thereby supporting the miniaturization and compact design of the overall lens structure.

[0067] By employing the aforementioned technical solution combining ten global surface lenses with all-conventional optical glass materials, this example achieves a balance between performance and cost in optical design. Without relying on aspherical or special materials, this optical solution effectively overcomes the major aberration challenges in achieving large target surfaces (e.g., 1.2 inches), high resolution, and low distortion through a precise optical architecture and material combination. Ultimately, it achieves excellent imaging performance while possessing significant cost advantages and industrial applicability.

[0068] In some examples of this application, the focal length of the industrial lens is f, the effective focal length of the first lens 1 is F1, and satisfies: 3≤F1 / f≤4. The effective focal length of the second lens 2 is F2, and satisfies: -0.4≤F1 / F2≤-0.2.

[0069] In this example of the application, the focal length of the industrial lens is defined as f, and the effective focal length of the first lens 1 is defined as F1, satisfying the relationship: 3 ≤ F1 / f ≤ 4. This condition constrains the relative strength between the optical power of the first lens 1 (biconvex positive lens) and the total optical power of the entire industrial lens. Its design aims to achieve a balance between structural compactness and optical performance, specifically: Setting the lower limit of the F1 / f ratio to 3 ensures that the first lens 1 has a sufficiently strong positive optical power, enabling it to undertake the main converging function of the first lens group (front group), laying the foundation for achieving the focal length required for industrial lenses, and helping to control the total optical length (TTL) of the lens.

[0070] Setting the upper limit of the F1 / f ratio to 4 constrains the optical power of the first lens 1 from being too strong, thereby effectively suppressing the spherical aberration introduced by it and avoiding the aberration correction burden on subsequent lenses due to excessive concentration of optical power in the lens group in the preceding optical path, thus ensuring the feasibility of the design and the robustness of the performance.

[0071] In other examples of this application, the effective focal length of the second lens 2 is F2, and it satisfies the relationship: -0.4 ≤ F1 / F2 ≤ -0.2. This relationship defines the ratio of optical power between the first lens 1 (a biconvex positive lens) and the second lens 2 (a meniscus negative lens) when they constitute the first cemented lens group. It is a key design parameter for achieving efficient achromatic correction. Specifically, a negative ratio F1 / F2 indicates that the optical power of the two lenses has opposite signs, which meets the basic requirements for constituting an achromatic cemented lens group. The range of the F1 / F2 ratio is limited to -0.4 to -0.2. This specific ratio of optical power matches the significant Abbe number difference between the optical glass materials used in the first lens 1 and the second lens 2 (for example, in one embodiment, the Abbe number difference ΔVd is approximately 15.2), together satisfying the achromatic condition, thereby enabling effective correction of axial chromatic aberration (positional chromatic aberration) generated by the first cemented lens group and the entire lens. This design achieves superior color difference control through a precise combination of conventional glass without relying on special dispersive materials.

[0072] In summary, in the industrial lens described in this application, the first lens (biconvex positive lens) and the second lens (meniscus negative lens) together constitute the first cemented lens group, and their synergistic effect is crucial to the system performance: the first lens 1, as the positive lens at the very front of the industrial lens, undertakes the main converging function of the lens and is the fundamental element that determines the focal length and total optical length of the lens. The second lens 2, as the negative lens, is cemented with it, which helps to balance the optical power distribution of the preceding optical path, thereby achieving a long working distance while keeping the total length of the lens compact. On this basis, the optical power signs of the two lenses are opposite and the focal length ratio is precisely constrained. Combined with the significant Abbe number difference between the two optical materials, they together form a highly efficient achromatic cemented group, which effectively corrects the axial chromatic aberration (positional chromatic aberration) of the lens without relying on special materials. In addition, the meniscus structure of the second lens 2 and its cementing design can also compensate for and balance the spherical aberration and field curvature generated by the first lens 1, thereby synergistically improving the imaging sharpness and consistency of the entire image field. Therefore, this combination, through careful matching of optical power and materials, constitutes a key unit integrating optical path convergence, structural control, chromatic aberration correction and aberration balance. It is one of the core elements of this application to achieve high resolution, low distortion and compact design under conventional glass material conditions.

[0073] In some examples of this application, the effective focal length of the third lens 3 is F3, the effective focal length of the fourth lens 4 is F4, and the following condition is satisfied: -23≤F3 / F4≤-17.

[0074] In this example of the application, the effective focal length of the third lens 3 is F3, and the effective focal length of the fourth lens 4 is F4, satisfying the relationship: -23 ≤ F3 / F4 ≤ -17. This condition constrains the core range of the optical power ratio between the third lens 3 (biconcave negative lens) and the fourth lens 4 (biconvex positive lens) in the second cemented lens group, and is the design basis for realizing specific aberration correction functions. Its specific function is reflected in the following aspects.

[0075] The third lens 3 and the fourth lens 4 have opposite signs of optical power (one negative and one positive), which forms the basic structure for chromatic aberration correction in the second cemented lens group. By constraining the absolute value of their focal length ratio F3 / F4 to 17~23, this significant asymmetric optical power distribution, combined with the appropriate difference in Abbe number (dispersion capability) between the two selected optical glass materials, enables the second cemented lens group to serve as a highly targeted correction unit. It effectively compensates for magnification chromatic aberration (i.e., the difference in image size caused by different wavelengths at different field of view positions) generated by industrial lenses, thereby ensuring the consistency of color across the entire image plane.

[0076] The proposed proportional relationship in this example, combined with the specific curvature parameters of the cemented surface, not only achieves chromatic aberration correction but also plays a crucial balancing role in the optical power distribution within the first lens group (front group). The strong positive optical power provided by the fourth lens 4 effectively shares the convergence capability required by the entire industrial lens. Simultaneously, this cemented structure design helps smooth the direction of light, positively contributing to the correction of astigmatism and suppression of field curvature, and avoiding other aberration deterioration that might be caused by excessive optical power from a single lens within the lens.

[0077] By strictly controlling the F3 / F4 ratio within the range provided in this example, the design of this second cemented lens group provides crucial support for achieving low distortion and high resolution optical performance in industrial lenses without relying on special materials. This control of the optical power ratio is also one of the technical manifestations of this application's goal of achieving excellent imaging quality and compact design using conventional glass materials and a novel architecture.

[0078] In some examples of this application, the effective focal length of the fifth lens 5 is F5, the effective focal length of the sixth lens 6 is F6, and satisfies: -0.7≤F5 / F6≤-0.2.

[0079] In this example of the application, the effective focal length of the fifth lens 5 is F5, and the effective focal length of the sixth lens 6 is F6, satisfying the relationship: -0.7 ≤ F5 / F6 ≤ -0.2. This condition constrains the core ratio range of the optical power of the fifth lens 5 (biconcave negative lens) and the sixth lens 6 (biconvex positive lens) when forming the third cemented lens group. The third cemented lens group is located on the image side of the aperture stop 11 and is adjacent to the aperture stop 11. It is a key unit in the second lens group (rear group) for realizing aberration correction and beam management.

[0080] The fifth lens 5 and the sixth lens 6 have opposite signs of optical power, forming an aberration-correcting cemented lens assembly. By constraining the focal length ratio F5 / F6 to -0.7 to -0.2, this specific asymmetrical optical power distribution, combined with the appropriate matching of the refractive index and Abbe number (dispersion coefficient) of the two lens materials, enables this third cemented lens assembly to efficiently correct axial chromatic aberration and magnification chromatic aberration of the lens. Simultaneously, it also has important compensation and balancing functions for residual spherical aberration and astigmatism produced by adjacent lenses (such as the seventh lens 7 and the eighth lens 8).

[0081] From the image-to-object optical path perspective, this third cemented lens group is the last lens group before the light enters the aperture 11. The aforementioned optical power ratio allows for precise adjustment of the beam converged by the preceding lenses, optimizing the aperture angle and wavefront shape of the beam, thereby ensuring that the light passes through the aperture in a more ideal state and with a higher fill rate. This not only improves the relative illumination and imaging contrast of the industrial lens but also provides good light incidence conditions for aberration correction of the first lens group after aperture 11, making it a key step in ensuring uniformity across the entire image field and high-resolution imaging.

[0082] The ratio range set in this example satisfies both optical performance requirements and structural design rationality. A reasonable focal length ratio helps avoid excessively extreme curvature in any lens (especially the negative lens) within the third cemented lens group, thus facilitating control of lens thickness and overall size, supporting lens miniaturization. This ratio is one of the key design guarantees for ensuring that industrial lenses can stably maintain low distortion (≤0.5%) and high resolution (MTF≥0.3 at 200 lp / mm spatial frequency) performance over a wide working distance (100mm~600mm).

[0083] In summary, the third cemented lens group that satisfies the relationship -0.7≤F5 / F6≤-0.2 is one of the core components of the industrial lens of this application, which achieves precise aberration control, optimizes optical path transmission, and supports the overall high performance and compactness goals.

[0084] In some examples of this application, the focal length of the industrial lens is f, the effective focal length of the seventh lens 7 is F7, and the following condition is satisfied: 0.5≤F7 / f≤1.5.

[0085] In this example of the application, the focal length of the industrial lens is f, and the effective focal length of the seventh lens 7 is F7, satisfying the relationship 0.5 ≤ F7 / f ≤ 1.5. This condition constrains the ratio between the optical power of the seventh lens (biconvex positive lens) and the total optical power of the entire industrial lens, and is one of the key design parameters for optical power distribution and aberration control in the second lens group (rear group). Its specific function is manifested as follows in the optical path perspective from the image side to the object side.

[0086] The seventh lens 7, as a high-power positive lens in the second lens group, has a focal length ratio (F7 / f) set between 0.5 and 1.5. The lower limit of 0.5 ensures that the seventh lens 7 possesses sufficient optical power to effectively share the converging function required in subsequent optical paths. This helps control the overall optical length (TTL) of the lens while maintaining the required focal length, supporting a compact optical structure design. The upper limit of 1.5 avoids excessively high optical power in the seventh lens 7, which could lead to an overly steep curvature or excessive thickness, thus facilitating manufacturing feasibility and balancing overall dimensions.

[0087] The seventh lens 7 is located between the eighth lens 8 (also a biconvex positive lens) and the sixth lens 6 (cemented with the fifth lens 5). The aforementioned focal length ratio range allows it to form a good transition in optical power and aberration compensation relationship with the preceding and following lenses. On one hand, it further shapes the beam converged by the eighth lens, helping to correct residual spherical aberration; on the other hand, its cooperation with the sixth lens 6 also has a positive effect on balancing astigmatism and field curvature, thereby improving the overall image sharpness and consistency.

[0088] In the overall optical architecture, maintaining the aforementioned proportional relationship between the effective focal length F7 of the seventh lens 7 and the focal length f of the lens is a crucial design element that ensures industrial lenses can achieve low distortion (≤0.5%) and high resolution (MTF≥0.3 at 200 lp / mm) over a wide working distance (100mm~600mm). This constraint ensures that the seventh lens 7 contributes the necessary optical power without introducing uncontrollable aberrations.

[0089] In summary, the seventh lens 7, which satisfies the condition 0.5≤F7 / f≤1.5, not only plays a crucial role in light convergence and optical structure control in the industrial lens, but is also an important component for achieving aberration balance and high-performance imaging.

[0090] In some examples of this application, the effective focal length of the eighth lens 8 is F8, and the effective focal length of the ninth lens 9 is F9, and satisfies: -1≤F8 / F9≤-0.4.

[0091] In this example of the application, the effective focal length of the eighth lens 8 is F8, and the effective focal length of the ninth lens 9 is F9, satisfying the relationship: -1≤F8 / F9≤-0.4. This condition defines the power ratio within the fourth cemented lens group formed by the eighth lens 8 (biconvex positive lens) and the ninth lens 9 (meniscus negative lens), and is a key design parameter for achieving specific aberration correction and performance optimization in the second lens group (rear group).

[0092] The focal length ratio F8 / F9 of the eighth lens 8 (positive optical power) and the ninth lens 9 (negative optical power) is negative, meeting the requirements for an achromatic cemented lens assembly. This ratio is limited to -1 to -0.4. This ratio, combined with the appropriate difference in Abbe number (dispersion coefficient) between the selected optical glass materials, enables this fourth cemented lens assembly to efficiently correct magnification chromatic aberration in industrial lenses. Simultaneously, this optical structure introduces necessary negative optical power into the optical path, helping to balance the strong converging tendency introduced by the seventh lens 7, eighth lens 8, etc., in the subsequent optical path, preventing excessive concentration of optical power, and creating conditions for overall aberration balance control.

[0093] The ninth lens 9 adopts a meniscus design with its concave surface facing the eighth lens 8 (i.e., facing the image side). Its concave surface mates with the negative power surface of the tenth lens 10 (a biconcave negative lens), forming a specific "negative-negative" relay structure in the optical path. The aforementioned F8 / F9 ratio range ensures that the fourth cemented lens group can provide a moderate negative power contribution, thereby enabling this relay structure to effectively correct optical distortion (especially distortion at the image field edges). This design helps optimize the distortion distribution pattern, promoting a more centrally symmetrical characteristic across the entire image field, and is one of the technical means to achieve the target of low distortion across the entire field (absolute value ≤0.5%).

[0094] By constraining the F8 / F9 ratio within the aforementioned range, this fourth cemented lens group achieves chromatic aberration and distortion correction while also possessing a more rational structure, helping to suppress potential higher-order aberrations. This is crucial for improving the imaging uniformity and consistency across the entire image plane, and for ensuring stable performance of industrial lenses over a wide working distance range (100mm~600mm). It serves as a design guarantee for achieving and maintaining high-resolution imaging (e.g., an MTF value of no less than 0.3 at a spatial frequency of 200 lp / mm).

[0095] In summary, the fourth cemented lens group that satisfies the specific relationship of -1≤F8 / F9≤-0.4 is the optical design in this application that achieves efficient magnification chromatic aberration correction, constructs a targeted low-distortion structure, and achieves excellent imaging performance.

[0096] In some examples of this application, the focal length of the industrial lens is f, the effective focal length of the tenth lens 10 is F10, and satisfies: -1≤F10 / f≤-0.3.

[0097] In this example of the application, the focal length of the industrial lens is f, and the effective focal length of the tenth lens 10 is F10, which must satisfy the relationship: -1≤F10 / f≤-0.3. This condition constrains the ratio between the optical power of the tenth lens 10 (biconcave negative lens) and the total optical power of the industrial lens. In the image-to-object optical path configuration, the tenth lens 10, as the first incident lens of the light, plays a crucial role in the lens's aberration correction, image field control, and structural adaptation, as specifically demonstrated below.

[0098] By limiting the F10 / f ratio to -1 to -0.3, the tenth lens 10 is ensured to have sufficient and appropriate negative optical power. This negative optical power is fundamental to correcting field curvature: it introduces an image plane curvature effect into the system that is opposite to that of the numerous positive lenses, thereby effectively counteracting the inherent field curvature tendency of the system and causing the final imaging plane to tend to be flat. This is crucial for adapting to large target surface planar sensors and achieving uniform, high-resolution imaging across the entire image field. At the same time, this negative optical power also provides the necessary balance and compensation for the optical power distribution within the entire second lens group (rear group).

[0099] The tenth lens 10 employs a biconcave negative lens design and works in conjunction with the ninth lens 9 (meniscus negative lens) to form a "negative-negative" relay optical architecture in the optical path. The specific negative optical power provided by the tenth lens 10, quantified by the F10 / f ratio, is crucial for the distortion correction function of this optical architecture. This structure allows for fine-tuning of the light path at the edge of the field of view, effectively suppressing optical distortion generated by the system, and is one of the core technical means to achieve the goal of low distortion (absolute value ≤0.5%) across the entire image field.

[0100] The tenth lens 10 is located on the image-side side of the entire industrial lens, and its optical power directly affects the lens's back focal length (BFL, i.e., the distance from the image-side side of the tenth lens to the image side). Constraining F10 / f within the aforementioned range allows for stable control of the back focal length at a reasonable size. This not only ensures the lens's mechanical structure is compatible with standard C-mount flange distance requirements but also provides design assurance for reserving installation space for components such as filters on the image-side, thereby significantly improving the lens's practicality and system integration adaptability.

[0101] In summary, the tenth lens 10, which satisfies the condition -1≤F10 / f≤-0.3, plays a role in correcting field curvature, participating in distortion control, and optimizing mechanical adaptability in this application. It is an important design for achieving excellent comprehensive performance of industrial lenses.

[0102] In some examples of this application, the total optical length (TTL) of the industrial lens satisfies: TTL≤60mm; the half-image height (Y) of the industrial lens satisfies: Y≥9.6mm; and the focal length (f) of the industrial lens is 35mm.

[0103] In this example of the application, the total optical length (TTL) of the industrial lens is ≤60mm; the half-image height (Y) of the industrial lens is ≥9.6mm; and the focal length (f) of the industrial lens is 35mm. The following is a detailed description of this combination of parameters.

[0104] In this application, the total optical length (TTL) of the industrial lens refers to the axial distance from the object-side side of the first lens 1 to the image-side side. This application, through a specially designed optical architecture (such as a focal length ratio of 0.5 ≤ Fa / Fb ≤ 1 for the front and rear lens groups) and precise lens arrangement, limits the total optical length (TTL) to within 60mm while ensuring optical performance. This compact size makes the lens structure lighter and smaller, significantly improving its installation flexibility and integration in industrial equipment, and meeting the stringent space requirements of automated inspection scenarios.

[0105] In this application, a half-image height Y ≥ 9.6 mm means that the industrial lens can support an image plane diameter of not less than 19.2 mm, thus completely covering the target surface of a 1.2-inch image sensor. This design enables the industrial lens to be adapted to sensors with high pixel counts of 16 to 20 million pixels, providing ample image plane information capacity for high-precision dimensional measurement and defect detection. While achieving a large image field, the industrial lens maintains excellent performance with high resolution (MTF ≥ 0.3 at 200 lp / mm) and low distortion (≤ 0.5%) across the entire image field, ensuring that the image edges and center are equally sharp and that geometric distortion is minimal.

[0106] The lens has a focal length f of 35mm, which is considered a medium focal length. Combined with a half-image height Y≥9.6mm, its diagonal field of view is approximately 29.2°. This configuration of focal length f and field of view achieves a good balance between observation range, imaging detail, and object-side working distance in industrial inspection applications. This industrial lens supports a wide working distance focusing range of 100mm to 600mm and can be adjusted within an aperture range of f / 2.8 to f / 16, enabling it to flexibly meet different application needs from close-range fine inspection to long-range large-scale observation while maintaining excellent image quality.

[0107] The combination of the three core parameters—TTL≤60mm, Y≥9.6mm, and f=35mm—is not merely a simple list of specifications, but rather a systematic achievement resulting from the specific optical design scheme described in this application (global surface glass, multi-ply assembly architecture, and precise optical power allocation). Together, these parameters signify that this industrial lens achieves high-performance, highly adaptable adaptation to large-area sensors within a compact physical size, thus providing a solution for applications such as machine vision inspection that combines excellent imaging quality, flexible operation, and cost-effectiveness.

[0108] In some examples of this application, the Abbe number of the first lens 1 is V1, the Abbe number of the second lens 2 is V2, and the following conditions are met: 10≤|V1-V2|≤20.

[0109] In this example of the application, the Abbe number of the first lens 1 is V1, and the Abbe number of the second lens 2 is V2, satisfying the relationship: 10 ≤ |V1 - V2| ≤ 20. This condition constrains the required range of difference in the material dispersion characteristics of the two lenses constituting the first cemented lens group, and is one of the parameters for achieving efficient achromatic design under the premise of using conventional optical glass materials.

[0110] The first lens 1 (biconvex positive lens) and the second lens 2 (meniscus negative lens) are cemented together to form a first cemented lens assembly. The Abbe number (Vd) is a key parameter for measuring the degree of dispersion of optical materials; the difference in Abbe numbers |V1-V2| directly reflects the degree of difference in the dispersion characteristics of the two materials. Controlling it between 10 and 20 ensures that the two conventional glass materials have a sufficiently significant dispersion difference. This difference is the fundamental physical condition for the cemented assembly to achieve chromatic aberration reduction, allowing the dispersion generated by the positive and negative lenses to be effectively canceled out at the cemented surface.

[0111] In one specific embodiment of this application, the first lens 1 (biconvex positive lens) and the second lens L2 (meniscus negative lens) are cemented together to form a first cemented lens assembly. The radius of curvature of the cemented surface of the two lenses is -35.07 mm, and this cemented surface itself contributes a certain negative optical power, complementing the positive optical power of the first lens 1. In this first cemented lens assembly, the Abbe number V1 of the material used for the first lens 1 is 42.7, and the Abbe number V2 of the material used for the second lens 2 is 27.5. The difference between their Abbe numbers, ΔVd, is 15.2, which is within the preferred range of 10 to 20.

[0112] This combination of materials and optical power design allows the first cemented lens assembly to effectively meet the achromatic condition: φ1 / V1 + φ2 / V2 ≈ 0 (where φ1 and φ2 are the optical powers of the first lens 1 and the second lens 2, respectively, and V1 and V2 are the Abbe numbers of the first lens 1 and the second lens 2, respectively). Under this condition, the chromatic dispersion produced by the first cemented lens assembly for different wavelengths of light is effectively canceled out, thereby significantly suppressing axial chromatic aberration (positional chromatic aberration) of the lens.

[0113] It should be noted that the Abbe number difference range in this example does not function independently, but is designed in conjunction with the specific power distribution ratio of the first cemented lens assembly (satisfying -0.4 ≤ F1 / F2 ≤ -0.2). Together, they ensure that the first cemented lens assembly accurately meets the achromatic conditions. By selecting conventional glass pairs with Abbe number differences within this range and combining this with a precisely calculated power ratio, the first cemented lens assembly can specifically correct axial chromatic aberration (positional chromatic aberration) generated by the system, effectively compensating for focus shifts caused by differences in refractive index for different wavelengths of light.

[0114] Setting the lower limit of |V1-V2| to 10 ensures dispersion correction capability; setting its upper limit to 20 avoids reliance on extremely special or expensive high-dispersion / low-dispersion materials. The Abbe number combination satisfying the condition 10≤|V1-V2|≤20 is a crucial material design basis for the first cemented lens group in this application to achieve efficient axial chromatic aberration correction without using special materials, thereby supporting the overall high resolution and excellent color reproduction capability of industrial lenses.

[0115] In some examples of this application, the radius of curvature of the surface of the seventh lens 7 near the eighth lens 8 is R72, and the radius of curvature of the surface of the eighth lens 8 near the seventh lens 7 is R81, and satisfies: 1.3≤|R72 / R81|≤1.4, and the air gap d78 between the seventh lens 7 and the eighth lens 8 satisfies: 0.1≤d78 / f≤0.15, where f is the focal length of the industrial lens.

[0116] In some examples of this application, the radius of curvature of the surface of the seventh lens 7 near the eighth lens 8 is R72, and the radius of curvature of the surface of the eighth lens 8 near the seventh lens 7 is R81, and both must satisfy: 1.3 ≤ |R72 / R81| ≤ 1.4; simultaneously, the air gap d78 between the seventh lens 7 and the eighth lens 8 must satisfy: 0.1 ≤ d78 / f ≤ 0.15, where f is the focal length of the industrial lens. These two conditions together define an asymmetric optical structure relationship with a specific spacing between two adjacent positive lenses, which is one of the key designs for optimizing aberration correction and improving image quality.

[0117] Both the seventh lens 7 and the eighth lens 8 are biconvex positive lenses, and they are made of the same or similar glass material. Controlling the ratio of the radii of curvature of their adjacent surfaces, |R72 / R81|, to 1.3~1.4 means that there is a moderate difference in the curvature of the two surfaces, forming an asymmetrical curvature pair. This design can introduce controllable astigmatism to compensate for astigmatism generated in other parts of the lens, thereby improving the overall sharpness of the image plane. This method of astigmatism compensation using adjacent lenses of the same material but different curvatures ensures the contribution of optical power while avoiding the introduction of additional materials or complex surface shapes.

[0118] The air gap d78 between the seventh lens 7 and the eighth lens 8 is constrained to a ratio of 0.1 to 0.15 to the focal length f of the entire industrial lens. Firstly, this provides the necessary conditions for ensuring the astigmatic correction function of the aforementioned asymmetric curvature surface. Secondly, this spacing helps to smooth the deflection of light as it passes through these two strongly positive power lenses, optimizing the beam propagation pattern and reducing the generation of higher-order aberrations. Furthermore, it is also one of the factors balancing the optical power and controlling the total optical length (TTL) of the lens.

[0119] The synergistic design of the curvature ratio and air gap described above is particularly beneficial for improving the imaging quality of the peripheral field of view. It effectively enhances the MTF (modulation transfer function) at the periphery of the image field and, in conjunction with the settings of other cemented lens groups and aperture positions, ensures that the lens maintains a stable MTF value of over 0.3 across the entire image field at a high spatial frequency of 200 lp / mm. This design is a crucial technical guarantee for the lens to achieve high resolution and uniform image quality while simultaneously achieving large target area coverage.

[0120] In one specific embodiment of this application, both the seventh lens L7 and the eighth lens L8 are designed as biconvex positive lenses and are made of the same optical glass material (e.g., conventional HZLAF55D glass with a refractive index Nd of approximately 1.83 and an Abbe number Vd of approximately 42.7). Despite using the same material, their curvature designs are differentiated: the radius of curvature R72 of the surface of the seventh lens L7 near the eighth lens L8 is -60.329 mm, while the radius of curvature R81 of the surface of the eighth lens L8 near the seventh lens L7 is 46.261 mm. The ratio of their radii of curvature, |R72 / R81|, is approximately 1.30, falling within the preferred range of 1.3 to 1.4. Furthermore, a 4.65 mm air gap is provided between the seventh lens L7 and the eighth lens L8.

[0121] This design introduces adjustable astigmatism into the lens by combining adjacent positive lenses of the same material but different curvatures and precisely controlled air gaps. This structural design effectively compensates for astigmatism generated by other parts of the lens, thereby improving the overall sharpness of the imaging plane, especially contributing to the image quality at the edges of the field of view. This method of aberration correction through differentiated design of spherical curvature and optimized spacing, without relying on special materials or aspherical surfaces, is one of the specific technical manifestations of the high resolution and uniform image field performance achieved by the global surface glass lens provided in this application.

[0122] In some examples of this application, the air gap between the aperture 11 and the fourth lens 4 is Ds, and the center thickness of the fifth lens 5 on the optical axis is Ct5, satisfying: 0.5≤Ds / Ct5≤0.6.

[0123] In this example of the application, the air gap between the aperture stop 11 and the fourth lens 4 is Ds, and the center thickness of the fifth lens 5 on the optical axis is Ct5, satisfying the relationship: 0.5 ≤ Ds / Ct5 ≤ 0.6. This condition defines a specific proportional relationship between the distance between the aperture stop 11 and the preceding lens, namely the fourth lens 4, and the center thickness of the immediately following lens, namely the fifth lens 5. This ratio is one of the key design parameters for optimizing the beam shape at the aperture stop 11, achieving aberration equalization, and improving edge imaging performance.

[0124] The ratio range proposed in this example ensures that the light has optimal beam aperture filling as it leaves the second lens group (rear group) and is about to pass through the aperture stop 11.

[0125] In one specific embodiment of this application, Ds is approximately 3.79 mm and Ct5 is approximately 7.00 mm, with a ratio of approximately 0.54, falling precisely within the range of 0.5 to 0.6. This design allows the beam to pass through the aperture 11 in a more saturated and controlled manner, thereby improving the uniformity of relative illumination on the image plane, especially enhancing the brightness at the edge of the image field, and ensuring uniform imaging of a large target surface.

[0126] The position of the aperture stop 11 and its spatial distribution before and after it have a significant impact on the balance of various aberrations. Controlling the ratio Ds / Ct5 within the range of 0.5 to 0.6 helps to create a smooth transition in optical power before and after the aperture stop 11. In the optical path from the image side to the object side, this design allows the light beam passing through the fifth lens 5 (belonging to the second lens group) to be shaped and pass through the aperture stop 11 in a better state, thus creating more favorable incident conditions for the light to enter the first lens group (front group) and continue aberration correction (especially the aberration correction undertaken by the cemented group of the fourth and third lenses). This enhances the synergy between the front and rear groups in aberration correction, which is a crucial element in achieving low distortion and high resolution across the entire optical spectrum. This ratio in this example exemplifies the refined design that enables industrial lenses to achieve excellent optical performance within a compact size with a total optical length TTL ≤ 60mm.

[0127] In some examples of this application, the distance between the tenth lens 10 and the image side on the optical axis is the back clipping BFL, and the focal length of the industrial lens is f, satisfying: 0.25≤BFL / f≤0.3.

[0128] In this example of the application, the tenth lens 10 is aligned with the image side (see...). Figure 1 The distance between the twentieth surface (S20) on the optical axis is the back focal length (BFL). The focal length of the industrial lens is f, and it satisfies the relationship: 0.25 ≤ BFL / f ≤ 0.3. Controlling the BFL / f ratio between 0.25 and 0.3 ensures that the physical dimensions of the industrial lens's back focal length (BFL) match the C-interface standard commonly used in industrial vision. This guarantees that the industrial lens can be directly installed with mainstream industrial cameras without special adjustments, significantly improving the plug-and-play capability and equipment integration efficiency of the industrial lens.

[0129] The scale range in this example corresponds to a reasonable back focal length (BFL) axial dimension. In one specific embodiment of this application, the BFL is designed to be 10.5 mm. This space can accommodate filters, polarizers, or other functional optical elements between the tenth lens 10 and the image sensor, allowing users to flexibly configure them according to different imaging environments (such as eliminating infrared interference and suppressing surface reflections), thereby expanding the application adaptability and functional customizability of industrial lenses.

[0130] This BFL / f ratio was achieved under the overall constraint of controlling the total optical length (TTL≤60 mm) of industrial lenses. It avoids structural redundancy caused by excessive back focal length, and also prevents sacrificing filter mounting space or mechanical compatibility due to excessive shortness, reflecting a balance between optical performance, mechanical adaptation, and usage flexibility within a limited size.

[0131] In some examples of this application, the modulation transfer function (MTF) value of the industrial lens at a spatial frequency of 200 lp / mm is not less than 0.3 in the visible light spectrum; and the absolute value of the maximum optical distortion of the industrial lens is not greater than 0.5%.

[0132] The industrial lens simultaneously meets two imaging performance indicators within the visible light spectrum: a modulation transfer function (MTF) value of not less than 0.3 at a spatial frequency of 200 lp / mm, and an absolute value of maximum optical distortion not exceeding 0.5%. These two indicators objectively and quantitatively define the high-performance level achieved by the lens from two dimensions: detail resolution and geometric fidelity.

[0133] The modulation transfer function (MTF) is a core parameter for evaluating the contrast and detail of an object reproduced by a lens. 200 lp / mm corresponds to a spatial frequency of 200 lines per millimeter on an image sensor, representing an extremely fine structure with a linewidth of only 5 micrometers. Even at this high frequency, the MTF value can still remain above 0.3. (See [link to relevant documentation]). Figure 2 , Figure 5 , Figure 8 and Figure 11 This demonstrates that the lens possesses exceptional high contrast transmission and detail resolution. This allows the lens to fully adapt to and leverage the potential of high-performance image sensors ranging from 16 to 20 megapixels, meeting the stringent requirements of modern high-precision industrial inspections such as semiconductor circuit testing and precision component appearance measurement for image sharpness and detail reproduction.

[0134] Optical distortion refers to the geometric shape distortion produced during imaging, which directly affects the accuracy of image-based dimensional measurements. To control the maximum absolute value of distortion across the entire field of view to within 0.5%, see [link to relevant documentation]. Figure 3 , Figure 6 , Figure 9 and Figure 12 This level of distortion is considered low. This ensures extremely high geometric fidelity in the image, which is crucial for applications requiring extremely high absolute geometric accuracy, such as semiconductor measurement and precision mechanical parts dimensional inspection, guaranteeing highly reliable and accurate measurement results.

[0135] Achieving both of the aforementioned metrics simultaneously demonstrates that the industrial lens provided in this application overcomes the technical contradiction commonly found in long-focal-length, large-area optical designs where high resolution and low geometric distortion are difficult to achieve simultaneously. The lens not only provides clear images capable of resolving micron-level details but also ensures highly realistic geometric shapes within the image itself. This makes it suitable not only for qualitative observation but also for providing a reliable hardware foundation for high-precision quantitative detection, measurement, and analysis based on machine vision, thus highlighting its core capability that distinguishes it from ordinary industrial lenses and enables it to handle high-end inspection tasks.

[0136] In one specific embodiment of this application, the parameters of each lens in the industrial lens are as follows: The first lens group includes the first lens 1 to the fourth lens 4: The first lens 1 is a biconvex positive lens: its front surface is the first surface S1 with a curvature of 70.194, its rear surface is the second surface S2 with a curvature of -35.07mm, the center thickness of the first lens 1 is 3.1mm, and the material is Nd=1.83 and Vd=42.7. The second lens 2 is a meniscus negative lens: its front surface is cemented with the second surface S2 and has a curvature of -35.07mm, its rear surface is the third surface S3 and has an infinite curvature, the center thickness of the second lens 2 is 2.75mm, the material is Nd=1.75, Vd=27.5, the first lens 1 and the second lens 2 are cemented together, and the air gap between the second lens 2 and the third lens 3 is 1.05mm; The third lens 3 is a biconcave negative lens: its front surface is the fourth surface S4 with a curvature of -42.262mm, its rear surface is the fifth surface S5 with a curvature of 30.945mm, the center thickness of the third lens 3 is 0.9mm, and the material is Nd=1.51, Vd=52.2. The fourth lens 4 is a biconvex positive lens: its front surface is cemented to the fifth surface S5 with a curvature of 30.945 mm, and its rear surface is the sixth surface S6 with a curvature of -76.481 mm. The center thickness of the fourth lens 4 is 6.59 mm, and the material is Nd=1.83, Vd=42.7. The air gap between the fourth lens 4 and the aperture stop 11 is 3.79 mm. The third lens 3 and the fourth lens 4 are double cemented together.

[0137] The second lens group includes the fifth lens 5 to the tenth lens 10; The fifth lens 5 is a biconcave negative lens: its front surface is the eighth surface S8 with a curvature of -19.796mm, its rear surface is the ninth surface S9 with a curvature of 25.86mm, the center thickness of the fifth lens 5 is 7mm, the material is Nd=1.67, Vd=32.2, and the air gap between the aperture stop S7 and the fifth lens 5 is 8.01mm. The sixth lens 6 is a biconvex positive lens: its front surface is cemented to the ninth surface S9 and has a curvature of 25.86 mm, its rear surface is the tenth surface S10 and has a curvature of 25.86 mm, the center thickness of the sixth lens 6 is 6.1 mm, the material is Nd=1.49, Vd=81.6, the fifth lens 5 and the sixth lens 6 are cemented together, and the air gap between them and the seventh lens 7 is 0.3 mm; The seventh lens 7 is a biconvex positive lens: its front surface is the eleventh surface S11 with a curvature of 60.329 mm, its rear surface is the twelfth surface S12 with a curvature of -60.329 mm, the center thickness of the seventh lens 7 is 6.06 mm, the material is Nd=1.83, Vd=42.7, and the air gap between the seventh lens 7 and the eighth lens 8 is 4.65 mm. The eighth lens 8 is a biconvex positive lens: its front surface is the thirteenth surface S13 with a curvature of 46.261 mm, its rear surface is the fourteenth surface S14 with a curvature of -21.614 mm, the center thickness of the eighth lens 8 is 5 mm, and the material is Nd=1.83 and Vd=42.7. The ninth lens 9 is a meniscus negative lens: its front surface is cemented to the fourteenth surface S14 with a curvature of -21.614, and its rear surface is the fifteenth surface S15 with infinite curvature. The center thickness of the ninth lens 9 is 0.9 mm, and the material is Nd=1.52, Vd=58.7. The eighth lens 8 and the ninth lens 9 are cemented together. The air gap between the ninth lens 9 and the tenth lens 10 is 2.43 mm. The tenth lens 10 is a biconcave negative lens: its front surface is the sixteenth surface S16 with a curvature of -24.43, its rear surface is the seventeenth surface S17 with a curvature of 42.926 mm, the center thickness of the tenth lens 10 is 6.5 mm, the material is Nd=1.68, Vd=31.2, and the air gap between the tenth lens and the image surface S20 is 10.5 mm.

[0138] The industrial lens provided in this application will be described in detail below through Examples 1 to 4.

[0139] Example 1 This embodiment 1 provides an industrial lens with the following optical structure: Figure 1 As shown. The industrial lens, along the optical axis from the image side to the object side, includes: a second lens group, an aperture stop 12, and a first lens group.

[0140] The second lens group (rear group) includes, from image side to object side, a tenth lens 10, a ninth lens 9, an eighth lens 8, a seventh lens 7, a sixth lens 6, and a fifth lens 5. Specifically: the tenth lens 10 is a biconcave negative lens; the ninth lens 9 is a meniscus negative lens, cemented together with the eighth lens 8; the eighth lens 8 is a biconvex positive lens; the seventh lens 7 is a biconvex positive lens; the sixth lens 6 is a biconvex positive lens, cemented together with the fifth lens 5; and the fifth lens 5 is a biconcave negative lens.

[0141] The first lens group (front group) includes a fourth lens 4, a third lens 3, a second lens 2, and a first lens 1 arranged sequentially from the image side to the object side. Among them: the fourth lens 4 is a biconvex positive lens and is cemented with the third lens 3; the third lens 3 is a biconcave negative lens; the second lens 2 is a meniscus negative lens and is cemented with the first lens 1; the first lens 1 is a biconvex positive lens.

[0142] See Figure 1 The concave surface of the second lens 2 faces the first lens 1, and the concave surface of the ninth lens 9 faces the eighth lens 8.

[0143] The combined focal length Fa of the first lens group is 45.3mm, and the combined focal length Fb of the second lens group is 59.2mm.

[0144] In this embodiment 1, the industrial lens consists of ten lenses, all of which are spherical lenses and are made of optical glass.

[0145] The optical parameters of the industrial lens in this embodiment 1 are detailed in Table 1.

[0146] Table 1

[0147] The optical parameters of the industrial lens provided in this embodiment 1 are as follows: Focal length f=35mm; Relative aperture: D / f′=1 / 3.2; Half-image height Y = 9.6mm (compatible with 1.2-inch sensor); TTL≤59.54mm; FNO=3.2; Working distance 600mm; See Figure 3 Its optical distortion is <0.5%; Applicable spectral range: 425nm~675nm; Resolution: 16 million to 20 million pixels; Field of view: 2ω = 29.2°.

[0148] Example 2 This embodiment 2 provides an industrial lens with the following optical structure: Figure 4 As shown. This industrial lens is identical to Example 1 in optical architecture, lens composition, materials, lens shape, order, and bonding relationship; that is, it also adopts the same... Figure 1 The diagram shows a dual-group split optical structure consisting of ten spherical optical glass lenses.

[0149] The detailed optical design parameters for this embodiment 2 are shown in Table 2.

[0150] Table 2

[0151] The optical parameters of the industrial lens provided in this embodiment 2 are as follows: Focal length f=35mm; Relative aperture: D / f′=1 / 3.2; Half-image height Y = 9.6mm (compatible with 1.2-inch sensor); TTL≤59.54mm; FNO=3.2; Working distance 420mm; See Figure 6 Its optical distortion is <0.5%; Applicable spectral range: 425nm~675nm; Resolution: 16 million to 20 million pixels; Field of view: 2ω = 29.2°.

[0152] Example 3 This embodiment 3 provides an industrial lens with the following optical structure: Figure 7 As shown. This industrial lens is identical to Example 1 in optical architecture, lens composition, materials, lens shape, order, and bonding relationship; that is, it also adopts the same... Figure 1 The diagram shows a dual-group split optical structure consisting of ten spherical optical glass lenses.

[0153] The detailed optical design parameters for this embodiment 3 are shown in Table 3.

[0154] Table 3

[0155] The optical parameters of the industrial lens provided in this embodiment 3 are as follows: Focal length f=35mm; Relative aperture: D / f′=1 / 3.2; Half-image height Y = 9.6mm (compatible with 1.2-inch sensor); TTL≤59.54mm; FNO=3.2; Working distance 240mm; See Figure 9 Its optical distortion is <0.5%; Applicable spectral range: 425nm~675nm; Resolution: 16 million to 20 million pixels; Field of view: 2ω = 29.2°.

[0156] Example 4 This embodiment 4 provides an industrial lens with the following optical structure: Figure 10 As shown. This industrial lens is identical to Example 1 in optical architecture, lens composition, materials, lens shape, order, and bonding relationship; that is, it also adopts the same... Figure 1 The diagram shows a dual-group split optical structure consisting of ten spherical optical glass lenses.

[0157] The detailed optical design parameters for this embodiment 4 are shown in Table 4.

[0158] Table 4

[0159] The optical parameters of the industrial lens provided in this embodiment 4 are as follows: Focal length f=35mm; Relative aperture: D / f′=1 / 3.2; Half-image height Y = 9.6mm (compatible with 1.2-inch sensor); TTL≤59.54mm; FNO=3.2; Working distance 120mm; See Figure 12 Its optical distortion is <0.5%; Applicable spectral range: 425nm~675nm; Resolution: 16 million to 20 million pixels; Field of view: 2ω = 29.2°.

[0160] It should be noted that the core difference between the four embodiments (Embodiments 1 to 4) lies in the air gap between the seventh lens 7 and the eighth lens 8, which are 4.65mm, 5.76mm, 8.57mm, and 15.34mm respectively. The corresponding working distances (WD) also vary accordingly, being 600mm, 420mm, 240mm, and 120mm respectively. This demonstrates that by changing the spacing between specific lens groups within the industrial lens (i.e., moving the lenses), the focal position of the lens can be adjusted continuously or segmentally to accommodate a wide range of working distances from 100mm to 600mm.

[0161] To verify the actual imaging performance of the industrial lens provided in this application embodiment, its key optical indicators were tested under standard test conditions (using 546nm monochromatic light as the light source), and the results are as follows: See Figure 2 , Figure 5 , Figure 8 and Figure 11 Modulation Transfer Function (MTF): At a high spatial frequency of 200 lp / mm, the MTF values ​​for each field of view are as follows: Central field of view: ≥0.42; 0.7 Field of view: ≥0.35; Edge field of view: ≥0.31; This data shows that the industrial lens provided in this application maintains a high contrast transmission capability across the entire image field, meeting the requirements for high-resolution imaging.

[0162] See Figure 3 , Figure 6 , Figure 9 and Figure 12 Field curvature and distortion: The field curvature was controlled within ±0.1mm, indicating a flat image plane and minimal defocusing at the edges of the field of view.

[0163] The absolute value of the maximum optical distortion across the entire field of view is 0.5%, achieving an extremely low distortion level and ensuring the geometric fidelity of the image.

[0164] The above test results verify the effectiveness of the industrial lens provided in this application embodiment in achieving the two core performance indicators: MTF@200lp / mm≥0.3 and maximum distortion≤0.5%.

[0165] in addition, Figure 13 The relative illumination distribution curve of the industrial lens provided in the embodiment of this application is shown. Figure 13 As shown, this industrial lens maintains high illumination uniformity across the entire image field, indicating excellent off-axis light transmission performance and effective control of image brightness attenuation. This characteristic ensures that even when using large-size image sensors, the entire target surface can obtain an image with uniform brightness, providing crucial support for subsequent accurate measurement and stable analysis in machine vision.

[0166] Compared with the prior art, the industrial lens provided in this application has the following advantages: By employing a specific optical architecture (such as a focal length ratio of 0.5 ≤ Fa / Fb ≤ 1 for the front and rear lens groups) and optimizing the curvature and spacing of each lens, this application controls the total optical length (TTL) of the industrial lens to within 60mm. The overall structure of the industrial lens is lightweight and compact, which not only facilitates installation and integration in industrial equipment but also improves the versatility and applicability of the integrated design.

[0167] The industrial lens of this application achieves excellent imaging quality while maintaining a large target area (compatible with 1.2-inch sensors) and a long working distance (100mm~600mm). Specifically: With a full-field modulation transfer function (MTF) value of no less than 0.3 in the visible light spectrum and at a high spatial frequency of 200 lp / mm, it can fully adapt to and utilize the resolution of image sensors ranging from 16 million to 20 million pixels, meeting the requirements for detecting micron-level details.

[0168] The maximum absolute value of optical distortion across the entire field of view does not exceed 0.5%, ensuring extremely high geometric fidelity of the image and providing a reliable guarantee for image-based precision dimensional measurement.

[0169] The achievement of the above effects relies on several key technical features that have undergone precise calculations and collaborative design: (1) For example, the first cemented lens assembly formed by cementing the first lens 1 and the second lens 2 has a bonding surface curvature (-35.07 mm) that produces negative optical power, which matches the positive optical power of the first lens 1. Combined with the Abbe number difference between the two materials (ΔVd=15.2), the achromatic condition is met, and axial chromatic aberration is effectively corrected. The other three cemented doublets also work together on a similar principle, achieving excellent chromatic aberration correction based on conventional glass materials.

[0170] (2) The seventh lens 7 and the eighth lens 8 are made of the same material. Through differentiated curvature design (such as R72=-60.329mm, R81=46.261 mm) and combined with specific air gaps (such as d78=4.65mm), astigmatism compensation effect is generated, which improves the image plane sharpness.

[0171] (3) The concave surface of the ninth lens 9 (curvature of -21.614mm) and the double concave surface of the tenth lens 10 form a negative-negative relay structure. Combined with optical power control, it can specifically correct optical distortion (especially edge distortion) so that the distortion distribution tends to be centrally symmetrical, thereby achieving a low distortion level of ≤0.5%.

[0172] (4) The distance Ds between the aperture stop 11 and the fourth lens 4 and the center thickness Ct5 of the fifth lens 5 meet a specific ratio (such as Ds / Ct5≈0.54). This design ensures that the light beam has the best aperture filling rate when entering the second lens group, which is beneficial to improving the uniformity of image illumination.

[0173] (5) The back focal length (BFL) from the tenth lens to the image side is designed to a specific value (e.g., 10.5 mm), and its ratio to the focal length satisfies 0.25 ≤ BFL / f ≤ 0.3. This allows the lens to be compatible with standard C-mount flange distances while also providing space for the installation of components such as filters, thus enhancing its practicality and system integration adaptability.

[0174] This application, through an innovative optical architecture and a series of specially designed parameter relationships, achieves performance improvements in industrial lenses in terms of miniaturization, high resolution, low distortion, wide working distance, and good compatibility based on conventional global glass materials, thereby providing a cost-effective solution suitable for high-precision machine vision inspection.

[0175] According to another embodiment of this application, a machine vision system is provided, the machine vision system including an industrial lens as described above and an image sensor, the image sensor being used to receive the image formed by the industrial lens.

[0176] Embodiments of this application also provide a machine vision system, which includes an industrial lens as described above and an image sensor. The image sensor is disposed on the imaging side of the industrial lens, and its target surface size is configured to match the imaging field of the industrial lens, thereby enabling complete reception of the high-quality optical image formed by the lens. This fit ensures that the lens's high resolution, low distortion, and other excellent optical performance are fully reflected in the final image signal.

[0177] The specific implementation of the machine vision system in this application can refer to the various embodiments of the industrial lens described above. Therefore, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, and will not be described in detail here.

[0178] The above embodiments mainly describe the differences between the various embodiments. As long as the different optimization features between the various embodiments are not contradictory, they can be combined to form a better embodiment. For the sake of brevity, they will not be elaborated here.

[0179] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.

Claims

1. An industrial lens, characterized in that, Along the optical axis, it includes the first lens group, the aperture (11), and the second lens group in sequence; The first lens group includes a first lens (1), a second lens (2), a third lens (3) and a fourth lens (4) in sequence. The first lens (1) is a biconvex positive lens, the second lens (2) is a meniscus negative lens, the third lens (3) is a biconcave negative lens, and the fourth lens (4) is a biconvex positive lens. The first lens (1) and the second lens (2) are cemented together, and the third lens (3) and the fourth lens (4) are cemented together. The second lens group includes, in sequence, a fifth lens (5), a sixth lens (6), a seventh lens (7), an eighth lens (8), a ninth lens (9), and a tenth lens (10). The fifth lens (5) is a biconcave negative lens, the sixth lens (6) is a biconvex positive lens, the seventh lens (7) is a biconvex positive lens, the eighth lens (8) is a biconvex positive lens, the ninth lens (9) is a meniscus negative lens, and the tenth lens (10) is a biconcave negative lens. The fifth lens (5) is cemented with the sixth lens (6), and the eighth lens (8) is cemented with the ninth lens (9). The first lens (1) to the tenth lens (10) are all spherical lenses and are all made of optical glass material.

2. The industrial lens according to claim 1, characterized in that, The working distance WD supported by the industrial lens and the focal length f of the industrial lens satisfy: 2.8≤WD / f≤17.1; wherein, the working distance WD is defined as the axial distance from the object-side surface of the first lens (1) of the industrial lens to the object plane where the observed object is located, and the working distance WD is 100mm~600mm; The aperture value F of the industrial lens is 2.8 ≤ F ≤ 16.

3. The industrial lens according to claim 1, characterized in that, The concave surface of the second lens (2) faces the first lens (1), and the concave surface of the ninth lens (9) faces the eighth lens (8).

4. The industrial lens according to claim 1, characterized in that, The industrial lens is composed of ten lenses, from the first lens (1) to the tenth lens (10), wherein the first lens (1) is located on the object side and the tenth lens (10) is located on the image side.

5. The industrial lens according to claim 1, characterized in that, The focal length of the industrial lens is f, and the effective focal length of the first lens (1) is F1, and satisfies: 3≤F1 / f≤4; The effective focal length of the second lens (2) is F2, and satisfies: -0.4≤F1 / F2≤-0.2; The effective focal length of the third lens (3) is F3, and the effective focal length of the fourth lens (4) is F4, and F3 and F4 satisfy: -23≤F3 / F4≤-17; The effective focal length of the fifth lens (5) is F5, and the effective focal length of the sixth lens (6) is F6, and F5 and F6 satisfy: -0.7≤F5 / F6≤-0.2; The effective focal length of the seventh lens (7) is F7, and satisfies: 0.5≤F7 / f≤1.5; The effective focal length of the eighth lens (8) is F8, and the effective focal length of the ninth lens (9) is F9, and F8 and F9 satisfy: -1≤F8 / F9≤-0.4; The effective focal length of the tenth lens (10) is F10, and satisfies: -1≤F10 / f≤-0.

3.

6. The industrial lens according to any one of claims 1-5, characterized in that, The total optical length (TTL) of the industrial lens satisfies: TTL≤60mm; The half-image height Y of the industrial lens satisfies: Y≥9.6mm; The focal length f of the industrial lens is 35mm.

7. The industrial lens according to claim 1, characterized in that, The Abbe number of the first lens (1) is V1, and the Abbe number of the second lens (2) is V2, and they satisfy: 10≤|V1-V2|≤20.

8. The industrial lens according to claim 1, characterized in that, The radius of curvature of the surface of the seventh lens (7) near the eighth lens (8) is R72, and the radius of curvature of the surface of the eighth lens (8) near the seventh lens (7) is R81, and satisfies: 1.3≤|R72 / R81|≤1.

4. The air gap d78 between the seventh lens (7) and the eighth lens (8) satisfies: 0.13≤d78 / f≤0.44, where f is the focal length of the industrial lens.

9. The industrial lens according to claim 1, characterized in that, The air gap between the aperture (11) and the fourth lens (4) is Ds, and the center thickness of the fifth lens (5) on the optical axis is Ct5, and satisfies: 0.5≤Ds / Ct5≤0.

6.

10. The industrial lens according to claim 1, characterized in that, The distance between the tenth lens (10) and the image side on the optical axis is the back clipping BFL, and the focal length of the industrial lens is f, which satisfies: 0.25≤BFL / f≤0.

3.

11. The industrial lens according to claim 1, characterized in that, Within the visible light spectrum, the modulation transfer function (MTF) value of the industrial lens at a spatial frequency of 200 lp / mm is not less than 0.3; the absolute value of the maximum optical distortion of the industrial lens is not greater than 0.5%.

12. A machine vision system, characterized in that, include: Industrial lens as described in any one of claims 1 to 11; as well as, An image sensor is used to receive the image formed by the industrial lens.

Images