A low-magnification, large-area telecentric lens and camera module

Abstract

This application provides a low-magnification, large-area telecentric lens and camera module. The low-magnification, large-area telecentric lens includes a first lens group, an aperture stop, and a second lens group arranged from the object side to the image side. Both the first and second lens groups have positive optical power. The first lens group includes seven lenses, and the second lens group includes at least four lenses. The lens located at the first position from the object side to the image side in the first lens group is the first lens, and the first lens has positive optical power. This low-magnification, large-area telecentric lens achieves a balance between a large target area, high image quality, and high yield rate.

Description

Technical Field

[0001] This application relates to the field of industrial line scan lens technology, and in particular to a low-magnification large-area telecentric lens and camera module. Background Technology

[0002] With the widespread use of cameras, higher demands are being placed on industrial line scan lenses. This is especially true for some industrial equipment, such as inspection devices used to inspect multilayer circuit boards, which require visual inspection of vias and blind holes. Existing inspection equipment is limited by the magnification and resolution of industrial line scan lenses, resulting in a limited field of view that can be inspected in a single pass. When inspecting large circuit boards, multiple scans are required to cover the entire board. Furthermore, the inconsistent hole depths on multilayer circuit boards mean that industrial line scan lenses have low inspection accuracy within the depth of field, failing to meet the requirements for precision inspection. Summary of the Invention

[0003] Embodiments of this application provide a low-magnification, large-area telecentric lens and camera module that can balance large target area and high imaging quality within a depth of field range.

[0004] To achieve the above objectives, the embodiments of this application adopt the following technical solutions: In a first aspect, embodiments of this application provide a low-magnification, large-target-area telecentric lens, including a first lens group, an aperture stop, and a second lens group arranged from the object side to the image side. Both the first lens group and the second lens group have positive optical power. The first lens group includes 7 lenses, and the second lens group includes at least 4 lenses. The lens located at the first position from the object side to the image side in the first lens group is the first lens, and the first lens has positive optical power.

[0005] In some possible implementations, the first lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged along the object side to the image side; the first lens group satisfies the relationship: 1.70 ≤ f L1 / f G1 ≤1.90; where f L1 f is the focal length of the first lens. G1 Let be the focal length of the first lens group.

[0006] In some possible implementations, the sixth lens and the seventh lens are cemented together to form a cemented lens; the second lens and the third lens are cemented together to form a cemented lens; and / or, the fourth lens and the fifth lens are cemented together to form a cemented lens.

[0007] In some feasible implementations, the second lens group satisfies the relationship: 0.9 ≤ f LX / f G2 ≤1.8; where f LX f is the focal length of the last lens in the second lens group located from the object side to the image side. G2 is the focal length of the second lens group.

[0008] In some possible implementations, the combined focal length f of the sixth lens and the seventh lens is... J03 Satisfies the relation: 70≤f J03 ≤90.

[0009] In some feasible ways, the refractive index Nd of the target lens X Satisfies the relation: 1.65 ≥ Nd X ≥1.43; and / or, the Abbe number Vd of the target lens X The relation 95.2 ≥ Vd is satisfied. X ≥60.0.

[0010] In some possible implementations, the first lens group includes the target lens; and / or, the second lens group includes the target lens; wherein the target lens has positive optical power and is any one of a meniscus lens, a biconvex lens, or a plano-convex lens.

[0011] In some feasible embodiments, the second lens group includes at least an eighth lens, a ninth lens, a tenth lens, and an eleventh lens arranged from the object side to the image side; the eighth lens has negative optical power, the ninth lens has positive optical power, and the eighth and ninth lenses are cemented together to form a cemented lens.

[0012] In some feasible implementations, the magnification of the low-magnification large-area telecentric lens is 0.33; and / or, the depth of field of the low-magnification large-area telecentric lens is 4.4 mm.

[0013] Secondly, embodiments of this application provide a camera module, including the low-magnification large-area telecentric lens and photosensitive element described in the first aspect, wherein the photosensitive element is disposed on the image side of the low-magnification large-area telecentric lens.

[0014] The low-magnification, large-area telecentric lens provided in this application embodiment can effectively balance aberrations by reasonably allocating the optical power of the first lens group and the second lens group. Simultaneously, the first lens in the low-magnification, large-area telecentric lens, located at the first position from the object side to the image side, has positive optical power, which is beneficial for converging a large range of light rays. This not only effectively gathers light from a wide field of view, thus preparing for subsequent imaging, but also helps ensure that the angle at which the main ray enters the low-magnification, large-area telecentric lens is nearly parallel, thereby effectively controlling telecentricity. Based on this, the optical power of each lens in the first lens group can be reasonably designed, which can not only further balance aberrations but also help reduce tolerance sensitivity, thereby achieving a balance between a large target area and high imaging quality, as well as reducing sensitivity to processing and assembly errors and improving yield. Attached Figure Description

[0015] Figure 1 This is a schematic diagram of the structure of the low-magnification, large-target-area telecentric lens provided in Embodiment 1 of this application; Figure 2 This is the MTF vs Field diagram of the low-magnification, large-target-area telecentric lens provided in Embodiment 1 of this application; Figure 3 This is the MTF chart of the low-magnification, large-target-area telecentric lens provided in Embodiment 1 of this application; Figure 4 This is the lateral chromatic aberration diagram of the low-magnification, large-surface telecentric lens provided in Embodiment 1 of this application; Figure 5 This is a distortion image of the low-magnification, large-target-area telecentric lens provided in Embodiment 1 of this application; Figure 6 This is a schematic diagram of the structure of the low-magnification, large-target-area telecentric lens provided in Embodiment 2 of this application; Figure 7 This is the MTF vs Field diagram of the low-magnification, large-target-area telecentric lens provided in Embodiment 2 of this application; Figure 8 This is the MTF chart of the low-magnification, large-target-area telecentric lens provided in Embodiment 2 of this application; Figure 9 This is the chromatic aberration diagram of the low-magnification, large-target-area telecentric lens provided in Embodiment 2 of this application; Figure 10 This is a distortion image of a low-magnification, large-target-area telecentric lens provided in Embodiment 2 of this application; Figure 11 This is a schematic diagram of the structure of the low-magnification, large-target-area telecentric lens provided in Embodiment 3 of this application; Figure 12 This is the MTF vs Field diagram of the low-magnification, large-target-area telecentric lens provided in Embodiment 3 of this application; Figure 13This is the MTF chart of the low-magnification, large-target-area telecentric lens provided in Embodiment 3 of this application; Figure 14 This is the chromatic aberration diagram of the low-magnification, large-target-area telecentric lens provided in Embodiment 3 of this application; Figure 15 This is a distortion diagram of a low-magnification, large-target-area telecentric lens provided in Embodiment 3 of this application.

[0016] The following are the labeling elements in the figure: First lens group G1; Second lens group G2; Third lens group G3; First compensation group G31; Second compensation group G32; Fourth lens group G4; First lens L1; Second lens L2; ​​Third lens L3; Fourth lens L4; Fifth lens L5; Sixth lens L6; Seventh lens L7; Eighth lens L8; Ninth lens L9; Tenth lens L10; Eleventh lens L11; Twelfth lens L12; Thirteenth lens L13; Fourteenth lens L14; Fifteenth lens L15; Aperture stop STO; Imaging plane IMAGE. Detailed Implementation

[0017] For ease of understanding, the English abbreviations and related technical terms used in the embodiments of this application will be explained and described below.

[0018] Focal power is equal to the difference between the convergence of the image-side beam and the convergence of the object-side beam. It characterizes the ability of a low-magnification, large-area telecentric lens to deflect light.

[0019] A lens or lens group with positive optical power, having a positive focal length, and having the effect of converging light.

[0020] A lens or lens group with negative optical power has a negative focal length and has the effect of diverging light.

[0021] Focal length, also known as focal length, is a measure of how well light converges or diverges in a lens. It refers to the perpendicular distance from the optical center of a lens or lens group to the focal plane when a distant object is focused into a sharp image. For prime lenses, the position of their optical center remains constant; for telephoto lenses, changes in the optical center result in changes in the focal length.

[0022] The effective focal length (EFL) of a lens refers to the distance from the center of the lens to the focal point.

[0023] The composite focal length is the combination of the focal lengths of the individual lenses in the lens group.

[0024] The object side is defined by the lens; the side where the object is located is called the object side, and the surface of the lens closest to the object side is called the object side surface.

[0025] The image side is the side on which the image of the subject is located, with the lens as the boundary. The surface of the lens closest to the image side is called the image side surface.

[0026] An aperture diaphragm is a device used to control the amount of light passing through the lens and entering the sensor inside the camera body; it is usually located inside the lens.

[0027] The imaging plane is located on the image side of all the lenses in the lens, and is the plane on which the image is formed after light passes through each lens in the lens in sequence.

[0028] The optical axis is a vertical axis that passes through the center of a lens. The lens optical axis is the axis that passes through the centers of each lens in the lens.

[0029] The focal point is the point where parallel light rays converge after being refracted by a lens or lens group.

[0030] The Abbe number, also known as the dispersion coefficient, is the ratio of the difference in refractive index of an optical material at different wavelengths, representing the degree of dispersion of the material.

[0031] Aberrations are the properties of a lens as an ideal optical system at the optical axis. A near-axis ray emitted from a point on an object intersects the image plane at a single point (i.e., the optical axis image point). However, in reality, light rays passing through different apertures of the lens rarely intersect perfectly at a single point. Instead, they deviate from the position of the near-axis image point. These differences are collectively referred to as aberrations.

[0032] Distortion, also known as image distortion, refers to the degree of distortion of the image formed by a lens relative to the object itself. Distortion is caused by the spherical aberration of the aperture. The height of the intersection point between the principal ray and the Gaussian image plane after passing through the lens in different fields of view is not equal to the ideal image height; the difference between the two is distortion.

[0033] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0034] In the embodiments of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "multiple" means two or more.

[0035] With the widespread use of cameras, higher demands are being placed on industrial line scan lenses. In particular, some industrial equipment, such as inspection equipment used to inspect multilayer circuit boards, requires visual inspection of through-holes and blind vias on multilayer circuit boards.

[0036] In multilayer circuit boards, a blind via (BV) refers to a via that starts from the top or bottom layer and penetrates only to a specific inner layer, avoiding the occupation of space on unrelated layers. This structure significantly improves routing flexibility, especially suitable for high-density designs with 8 or more layers, and is commonly found in high-end devices such as smartphones, servers, and automotive electronics. The main function of a blind via is to save space in high-density interconnect (HDI) designs, avoiding the excessive wiring area occupied by traditional through-hole vias. Because it does not penetrate all layers, blind vias can effectively reduce signal path length, reduce parasitic capacitance and reflection, and improve high-frequency performance. In terms of structural design, blind vias require precise control of drilling depth and interlayer alignment to ensure accurate connection with the target inner layer pads. Improper design or manufacturing can easily lead to problems such as plating voids and hole wall cracks, affecting reliability.

[0037] Existing inspection equipment is limited by the magnification and resolution of industrial line scanning lenses, resulting in a limited field of view that can be inspected in a single pass. When inspecting large circuit boards, multiple scans are required to detect the entire board. Furthermore, for multi-layer circuit boards with inconsistent hole depths, the low inspection accuracy of industrial line scanning lenses within the depth of field fails to meet precision inspection requirements.

[0038] like Figure 1 As shown in the figure, this application embodiment provides a camera module, which includes a low-magnification large-area telecentric lens and a photosensitive element (not shown in the figure). The photosensitive element is located on the image side of the low-magnification large-area telecentric lens.

[0039] The working principle of this camera module is as follows: the light reflected from the subject passes through a low-magnification, large-area telecentric lens to generate an optical image, which is then projected onto the photosensitive surface of the photosensitive element. The photosensitive element converts the optical image into an electrical signal, i.e., an analog image signal, and transmits it to the processor.

[0040] Among them, the photosensitive element (also known as the image sensor, is located in, for example, ...) Figure 1The image sensor on the far right (IMAGE) is a semiconductor chip containing hundreds of thousands to millions of photodiodes that generate electrical charges when illuminated. The photosensitive element can be a charge-coupled device (CCD) or a complementary metal-oxide-semiconductor (CMOS) device. A CCD is made of a highly sensitive semiconductor material that converts light into electrical charges. A CCD consists of many photosensitive units, typically measured in megapixels. When light illuminates the surface of the photosensitive element, each photosensitive unit reflects a charge onto the component; the signals from all the photosensitive units are added together to form a complete image.

[0041] Among them, the low-magnification, large-aperture, telecentric lens is a fixed-focus lens, which can be simply referred to as a lens. This lens is an optical lens that mainly uses the refraction principle of lenses to form an image. That is, when light from a scene passes through this low-magnification, large-aperture, telecentric lens, a clear image is formed on the focal plane, and the image of the scene is recorded by a photosensitive element located on the focal plane.

[0042] like Figure 1 As shown, this application embodiment provides a low-magnification, large-area telecentric lens, including a first lens group G1, an aperture stop (STOP), and a second lens group G2 arranged along the object side to the image side. Both the first lens group G1 and the second lens group G2 have positive optical power. The first lens group G1 includes 7 lenses, and the second lens group G2 includes at least 4 lenses. That is, this low-magnification, large-area telecentric lens includes at least 11 lenses.

[0043] By properly allocating the optical power of the two lens groups in a low-magnification, large-target-area telecentric lens, aberrations can be effectively corrected, thereby improving image quality.

[0044] refer to Figure 1 The first lens group G1 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7 arranged from the object side to the image side. The first lens L1 has optical power, which is beneficial for converging a large range of light rays. It can not only effectively collect light rays with a large field of view, thus preparing for subsequent imaging, but also, by pre-converging the light rays, it helps to ensure that the angle of the main ray incident on the low-magnification, large-target telecentric lens is close to parallel, thereby effectively controlling the telecentricity.

[0045] Based on this, in some feasible ways, the focal length f of the first lens L1 can be reasonably allocated. L1 The focal length f of the first lens group G1 G1 The above ratio f L1 / fG1 It is for the purpose of precisely controlling the distribution of optical power, and its core objective is to balance aberrations.

[0046] If the aforementioned ratio is too large, the optical focal length of the first lens L1 will be too strong, introducing serious problems such as spherical aberration and chromatic aberration, which is not conducive to the correction of aberrations by subsequent lenses. If the aforementioned ratio is too small, the optical focal length of the first lens L1 will be too weak, which is not conducive to realizing a large target surface. When the focal length of the first lens L1 and the focal length of the first lens group G1 satisfy the above relationship 1.70≤f L1 / f G1 When the value is ≤1.90, not only can aberrations be further balanced, but tolerance sensitivity can also be reduced, thereby achieving a balance between large target area and high imaging quality, as well as reducing the sensitivity to processing and assembly errors and improving yield.

[0047] The second lens group G2 mentioned above may include 4 lenses, or it may include 5, 6, 7, or 8 lenses. That is to say, in addition to the above-mentioned 11 lenses, the number of lenses in the low-magnification large-target telecentric lens can also be selected by the user according to optical requirements, such as 12, 13, 14, or 15 lenses, etc., without specific limitation here.

[0048] In some feasible ways, the first lens group G1 includes at least one cemented lens.

[0049] The above-mentioned cemented lens is formed by cementing two or three lenses together.

[0050] The first lens group G1 includes a cemented lens, which can not only reasonably correct the chromatic aberration of the low-magnification large-format telecentric lens, but also reduce the tolerance sensitivity of the low-magnification large-format telecentric lens, effectively improve the overall image quality of the low-magnification large-format telecentric lens, and facilitate assembly.

[0051] In some feasible implementations, the low-magnification, large-target-area telecentric lens in the embodiments of this application satisfies the relationship: 70 ≤ f J03 ≤90.

[0052] Among them, f J03 It is the combined focal length of the sixth lens L6 and the seventh lens L7.

[0053] By rationally designing the optical power of the sixth lens L6 and the seventh lens L7, the combined focal length of the sixth lens L6 and the seventh lens L7 satisfies the above relationship. In this way, the light entering the stop after passing through the seventh lens L7 is as smooth as possible, thereby reducing the sensitivity of the system.

[0054] In some feasible ways, the second lens group G2 includes at least one cemented lens, which can further improve image quality and simplify the assembly process.

[0055] In some feasible implementations, a low-magnification, large-target-area telecentric lens includes a target lens having positive optical power. The target lens can be a meniscus lens with positive optical power, also known as a positive meniscus lens.

[0056] Positive meniscus lenses have a positive focal length and converge light rays. Compared with simple lenses such as plano-convex lenses, positive meniscus lenses can significantly reduce spherical aberration when converging or collimating light rays, thereby obtaining a smaller focused spot and higher image quality. At the same time, they are also beneficial for shortening the system focal length and increasing the system numerical aperture, thereby collecting more light rays and improving resolution and image brightness.

[0057] Of course, the target lens can also be a biconvex lens or a plano-convex lens with positive optical power; no specific limitation is made here.

[0058] In some feasible ways, the refractive index Nd of the target lens X Satisfying the relation: 1.65≥Nd X ≥1.43; Abbe number Vd of the target lens X The relation 95.2 ≥ Vd is satisfied. X ≥60.0.

[0059] In some feasible implementations, the second lens group G2 satisfies the relation: 0.9 ≤ f LX / f G2 ≤1.8.

[0060] in, This refers to the lens in the second lens group G2 that is located at the last position from the object side to the image side, i.e. Figure 1 The focal length of the twelfth lens L12 in the image.

[0061] By rationally designing the focal lengths of the second lens group G2 and the twelfth lens L12, a smaller image-side principal ray incident angle (i.e., CRA angle) can be achieved when the above ratio satisfies the relationship.

[0062] It should be noted that "low magnification" in the aforementioned low-magnification large-target-area telecentric lens refers to a lens with a magnification of 1.0 or less. Typically, low-magnification telecentric lenses have a larger field of view, covering a wider detection range. They also have a larger working distance, maintaining overall clarity even when the height of the object being inspected varies, such as the depth of blind holes in multi-layer circuits. This particular low-magnification large-target-area telecentric lens is a fixed-focus lens; the following description will use a magnification of 0.33.

[0063] like Figure 1A schematic diagram of the structure of a low-magnification, large-area telecentric lens according to Embodiment 1 of this application is shown. This low-magnification, large-area telecentric lens includes a first lens group G1, an aperture stop (STOP), and a second lens group G2 arranged along the object side to the image side. Both the first lens group G1 and the second lens group G2 have positive optical power. The first lens group G1 includes 7 lenses, and the second lens group G2 includes 5 lenses. That is, this low-magnification, large-area telecentric lens includes 12 lenses.

[0064] refer to Figure 1 The first lens group G1 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7 arranged from the object side to the image side; the second lens L2 and the third lens L3 are cemented together to form a cemented lens, and the fourth lens L4 and the fifth lens L5 are cemented together to form a cemented lens. The second lens group G2 includes an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11, and a twelfth lens L12 arranged from the object side to the image side; the eighth lens L8 and the ninth lens L9 are cemented together to form a cemented lens, and the tenth lens L10 and the eleventh lens L11 are cemented together to form a cemented lens.

[0065] Tables 1a to 1c provide the specific parameter values ​​for each lens of the low-magnification, large-target-area telecentric lens in one of the optional embodiments of Embodiment 1 of this application.

[0066]

[0067] It should be noted that in Table 1a, "Surface Number" refers to the number of each surface arranged sequentially from the object side to the image side. The radius R value is the lens corresponding to the surface number, that is, the radius of curvature of the object side or image side of the lens corresponding to each surface number at the optical axis. "Infinite" in the "Radius of Curvature" parameter series means that the object side or image side of the lens is a plane. The value of each lens in the "Thickness / Spacing" parameter series is the thickness of the lens on the optical axis. The value of the stop STO in the "Thickness" parameter series is the distance on the optical axis from the center of the stop STO to the object side of the next lens. "IMAGE" corresponds to the imaging surface of a low-magnification, large-target-area telecentric lens, which in this embodiment refers to... Figure 1 The image plane on the far right of the low-magnification, large-target telecentric lens shown. The value of "Aperture Stop STO" at the thickness in Table 1a represents the distance between the aperture stop STO and the eighth lens L8.

[0068] In this embodiment, the conjugate distance of the low-magnification, large-target-area telecentric lens is: OI = 1200mm; optimal working distance: WD0 = 420mm; depth of field range: 417.8mm-422.2mm; target area: 82mm; working wavelength: visible light; object-side telecentricity: TELE OBJ≤0.1°; Relative illuminance: RI≥90%.

[0069] The second lens L2, the fourth lens L4, and the eleventh lens L11 mentioned above are all target lenses. The refractive index Nd of the target lenses... X Satisfies the relation: 1.65 ≥ Nd X ≥1.43. Abbe number Vd of the target lens. X The relation 95.2 ≥ Vd is satisfied. X ≥60.0.

[0070] The positive and negative values ​​of the optical power of each lens in the low-magnification, large-target-area telecentric lens of Example 1 are shown in Table 1b.

[0071]

[0072] It should be noted that the "+" and "-" in Table 1b represent the positive and negative optical power of each lens in the low-magnification, large-target-area telecentric lens of Example 1. "+" indicates that the lens has positive optical power; "-" indicates that the lens has negative optical power.

[0073] The concavity or convexity of the object side or image side of each lens in the low-magnification, large-target-area telecentric lens of Example 1 at the optical axis is shown in Table 1c.

[0074]

[0075] It should be noted that in Table 1c, “++”, “+-”, “-+”, and “--” represent the concavity or convexity of the object-side or image-side of each lens at the optical axis. Specifically, “++” indicates that both the object-side and image-side of the lens are convex towards the object at the optical axis, meaning the lens is a meniscus lens that convex towards the object; “+-” indicates that both the object-side and image-side of the lens are convex towards the object at the optical axis, meaning it is a biconvex lens; “-+” indicates that both the object-side and image-side of the lens are concave towards the object at the optical axis, meaning it is a biconcave lens; and “--” indicates that both the object-side and image-side of the lens are concave towards the object at the optical axis, meaning it is a meniscus lens that convex towards the image. Of course, in addition to the concave and convex configurations mentioned above, the lenses in a low-magnification, large-target-area telecentric lens may also include any one or more of the following: "∞+", "∞-", "-∞", "∞+", and "+∞". "∞+" represents a lens where the object-side surface is flat along the optical axis, and the image-side surface is convex towards the object along the optical axis; "∞-" represents a lens where the object-side surface is flat along the optical axis, and the image-side surface is concave towards the object along the optical axis; "-∞" represents a lens where the object-side surface is concave towards the object along the optical axis, and the image-side surface is flat along the optical axis; and "+∞" represents a lens where the object-side surface is convex towards the object along the optical axis, and the image-side surface is flat along the optical axis. No specific limitations are made here.

[0076] Combination Figure 1 A schematic diagram of the low-magnification, large-area telecentric lens in Example 1 is shown, along with Tables 1a to 1c which list the main parameters of the low-magnification, large-area telecentric lens in Example 1, and the concavity / convexity of each lens at the optical axis. Simulations were used to obtain simulation diagrams of the MTF vs. Field, MTF, transverse chromatic aberration, and distortion of the low-magnification, large-area telecentric lens in Example 1.

[0077] Both MTF vs Field plots and MTF plots are graphs reflecting the contrast (fidelity) of low-magnification, large-aperture telecentric lenses. The MTF plot is a modulation transfer function plot; the horizontal axis represents the distance from the center to the edge, while the vertical axis reflects the quality of contrast, or fidelity. A higher vertical value on the MTF plot indicates better fidelity and higher resolution for medium-to-long telephoto, low-magnification, large-aperture telecentric lenses.

[0078] The above-mentioned vertical axis chromatic aberration diagram, also known as the magnification chromatic aberration diagram, shows that the image height / magnification is inconsistent along the direction perpendicular to the optical axis. This diagram visually demonstrates the differences in image height caused by different magnification when light of different wavelengths is imaged.

[0079] The distortion graph above represents the percentage distortion of a low-magnification, large-area telecentric lens as the field of view changes, where the horizontal axis represents the percentage distortion and the vertical axis represents the normalized field of view height.

[0080] The above descriptions of simulation graphs such as MTF vs Field plots, MTF plots, vertical axis chromatic aberration plots, and distortion plots are the same as those in other embodiments, and will not be repeated below.

[0081] from Figures 2 to 3 This demonstrates that the low-magnification, large-area telecentric lens in this embodiment exhibits minimal image fidelity and edge quality degradation at a magnification of 0.33, indicating that the low-magnification, large-area telecentric lens meets optical performance requirements at low magnification. From... Figure 4 It can be seen that the chromatic aberration along the vertical axis within the field of view is no greater than 2μm, and the photographed object is not prone to chromatic dispersion. From Figure 5 It can be seen that the distortion correction is excellent, and the image is basically free of distortion.

[0082] Figure 6 A schematic diagram of the structure of the low-magnification large-target-area telecentric lens of Embodiment 2 is shown. The main difference between the low-magnification large-target-area telecentric lens of Embodiment 2 and the low-magnification large-target-area telecentric lens of Embodiment 1 is that the parameters and conditions satisfied by each lens in the second embodiment are different, as are the concavity and convexity of the object side or image side of each lens at the optical axis.

[0083] This low-magnification, large-area telecentric lens includes a first lens group G1, an aperture stop (STOP), and a second lens group G2 arranged from the object side to the image side. Both the first lens group G1 and the second lens group G2 have positive optical power. The first lens group G1 includes 7 lenses, and the second lens group G2 includes 5 lenses. In other words, this low-magnification, large-area telecentric lens includes 12 lenses.

[0084] refer to Figure 6 The first lens group G1 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7 arranged from the object side to the image side; the second lens L2 and the third lens L3 are cemented together to form a cemented lens, and the fourth lens L4 and the fifth lens L5 are cemented together to form a cemented lens. The second lens group G2 includes an eighth lens L8, a ninth lens L9, a tenth lens L10, an eleventh lens L11, and a twelfth lens L12 arranged from the object side to the image side; the eighth lens L8 and the ninth lens L9 are cemented together to form a cemented lens, and the tenth lens L10 and the eleventh lens L11 are cemented together to form a cemented lens.

[0085] Tables 2a to 2c provide the specific parameter values ​​for each lens of the low-magnification, large-target-area telecentric lens in one of the optional embodiments of Embodiment 2 of this application.

[0086]

[0087] In this embodiment, the conjugate distance of the low-magnification, large-target-area telecentric lens is: OI = 1180 mm; optimal working distance: WD0 = 400 mm; depth of field range: 397.8 mm - 402.2 mm; target area: 82 mm; working wavelength: visible light; object-side telecentricity: TELE OBJ ≤0.1°; Relative illuminance: RI≥90%.

[0088] The second lens L2, the fourth lens L4, and the eleventh lens L11 mentioned above are all target lenses. The refractive index Nd of the target lenses... X Satisfies the relation: 1.65 ≥ Nd X ≥1.43.

[0089] The positive and negative values ​​of the optical power of each lens in the low-magnification, large-target-area telecentric lens of Example 2 are shown in Table 2b.

[0090]

[0091] The concavity or convexity of the object side or image side of each lens in the low-magnification, large-target-area telecentric lens of Example 2 at the optical axis is shown in Table 2c.

[0092]

[0093] Combination Figure 6 The provided schematic diagram of the low-magnification large-target telecentric lens in Embodiment 2, and Tables 2a to 2c show the main parameters of the low-magnification large-target telecentric lens in Embodiment 2, as well as the concavity and convexity of each lens at the optical axis.

[0094] from Figures 7 to 8 This demonstrates that the low-magnification, large-area telecentric lens in this embodiment exhibits minimal image fidelity and edge quality degradation at a magnification of 0.33, indicating that the low-magnification, large-area telecentric lens meets optical performance requirements at low magnification. From... Figure 9 It can be seen that the chromatic aberration along the vertical axis within the field of view is no greater than 2μm, and the photographed object is not prone to chromatic dispersion. From Figure 10 It can be seen that the distortion correction is excellent, and the image is basically free of distortion.

[0095] Figure 11 A schematic diagram of the structure of the low-magnification large-target-area telecentric lens of Embodiment 3 is shown. The main differences between the low-magnification large-target-area telecentric lens of Embodiment 3 and the low-magnification large-target-area telecentric lens of Embodiment 1 are: the number of lenses in the second lens group G2 of the low-magnification large-target-area telecentric lens, the parameters and conditions satisfied by each lens in the low-magnification large-target-area telecentric lens, and the concavity and convexity of the object side or image side of each lens at the optical axis.

[0096] like Figure 11 As shown, this low-magnification, large-target-area telecentric lens includes a first lens group G1, an aperture stop (STOP), and a second lens group G2 arranged from the object side to the image side. Both the first lens group G1 and the second lens group G2 have positive optical power. The first lens group G1 includes 7 lenses, and the second lens group G2 includes 4 lenses. In other words, this low-magnification, large-target-area telecentric lens includes 11 lenses.

[0097] refer to Figure 11 The first lens group G1 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5, a sixth lens L6, and a seventh lens L7 arranged from the object side to the image side; the second lens L2 and the third lens L3 are cemented together to form a cemented lens, and the fourth lens L4 and the fifth lens L5 are cemented together to form a cemented lens. The second lens group G2 includes an eighth lens L8, a ninth lens L9, a tenth lens L10, and an eleventh lens L11 arranged from the object side to the image side; the eighth lens L8 and the ninth lens L9 are cemented together to form a cemented lens.

[0098] Tables 3a and 3c respectively provide the specific parameter values ​​of each lens of the low-magnification large-target telecentric lens in an optional embodiment of Embodiment 3 of this application.

[0099]

[0100] In this embodiment, the conjugate distance of the low-magnification, large-target-area telecentric lens is: OI = 1160mm; optimal working distance: WD0 = 380mm; depth of field range: 377.8mm-382.2mm; target area: 82mm; working wavelength: visible light; object-side telecentricity: TELE OBJ ≤0.1°; Relative illuminance: RI≥90%.

[0101] The second lens L2, the fourth lens L4, and the tenth lens L10 mentioned above are all target lenses.

[0102] The positive and negative values ​​of the optical power of each lens in the low-magnification, large-target-area telecentric lens of Example 3 are shown in Table 3c.

[0103]

[0104] The concavity or convexity of the object side or image side of each lens in the low-magnification, large-target-area telecentric lens of Example 3 at the optical axis is shown in Table 3d.

[0105]

[0106] Combination Figure 11 The provided schematic diagram of the low-magnification large-target telecentric lens in Embodiment 3, and Tables 3a to 3c show the main parameters of the low-magnification large-target telecentric lens in Embodiment 3, as well as the concavity and convexity of each lens at the optical axis.

[0107] from Figures 12 to 13 This demonstrates that the low-magnification, large-area telecentric lens in this embodiment exhibits minimal image fidelity and edge quality degradation at a magnification of 0.33, indicating that the low-magnification, large-area telecentric lens meets optical performance requirements at low magnification. From... Figure 14 It can be seen that the chromatic aberration along the vertical axis within the field of view is no greater than 2μm, and the photographed object is not prone to chromatic dispersion. From Figure 15 It can be seen that the distortion correction is excellent, and the image is basically free of distortion.

[0108] Table 4 shows the numerical values ​​corresponding to the relationships satisfied by the low-magnification, large-target-area telecentric lenses in the above three embodiments.

[0109]

[0110] Note: The following annotations explain the relationship between the low-magnification, large-target-area telecentric lenses in the various embodiments: f G1 The focal length of the first lens group G1 of the low-magnification, large-target telecentric lens; f G2The focal length of the second lens group G2 of the low-magnification, large-target telecentric lens; f L1 Let L be the focal length of the first lens L1 in the first lens group G1; f J03 It is the sum of the focal lengths of the sixth lens L6 and the seventh lens L7; f LX It is the focal length of the lens in the second lens group G2, located at the last position from the object side to the image side.

[0111] In summary, the low-magnification, large-target-area telecentric lens in this embodiment has a magnification of 0.33 and a depth of field of 4.4mm. This means that within a minimum working distance offset of ±2.2mm, clear imaging is guaranteed, exhibiting good consistency in distortion and chromatic aberration across a large depth of field. The target area reaches 82mm, the object-side telecentricity is less than or equal to 0.1°, and the relative illumination is greater than or equal to 90%. When equipped with a 16K line scan camera with a pixel size of 5 micrometers, an object-side resolution of 15.15 micrometers can be achieved, meeting the resolution requirements for multi-layer blind hole detection. With a target area of ​​82mm and an object-side field of view of 248mm, a sufficiently large field of view ensures high resolution and consistent imaging across the depth of field, enabling efficient and accurate multi-layer blind hole inspection.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application.

Claims

1. A low-magnification, large-target-area telecentric lens, characterized in that, It includes a first lens group, an aperture, and a second lens group arranged along the object side to the image side, both of which have positive optical power; The first lens group includes 7 lenses, and the second lens group includes at least 4 lenses; the lens located at the first position from the object side to the image side in the first lens group is the first lens, and the first lens has positive optical power.

2. The low-magnification, large-target-area telecentric lens according to claim 1, characterized in that, The first lens group includes a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, and a seventh lens arranged along the object side to the image side; The first lens group satisfies the relationship: 1.70 ≤ f L1 / f G1 ≤1.90; Among them, f L1 f is the focal length of the first lens. G1 Let be the focal length of the first lens group.

3. The low-magnification, large-target-area telecentric lens according to claim 2, characterized in that, The sixth lens and the seventh lens are cemented together to form a cemented lens; The second lens and the third lens are cemented together to form a cemented lens, and / or the fourth lens and the fifth lens are cemented together to form a cemented lens.

4. The low-magnification, large-target-area telecentric lens according to claim 1, characterized in that, The second lens group satisfies the relationship: 0.9 ≤ f LX / f G2 ≤1.8; Among them, f LX f is the focal length of the last lens in the second lens group located from the object side to the image side. G2 is the focal length of the second lens group.

5. The low-magnification, large-target-area telecentric lens according to claim 1, characterized in that, The combined focal length f of the sixth lens and the seventh lens J03 Satisfies the relation: 70≤f J03 ≤90.

6. The low-magnification, large-target-area telecentric lens according to claim 5, characterized in that, The refractive index Nd of the target lens X Satisfies the relation: 1.65 ≥ Nd X ≥1.43; and / or, the Abbe number Vd of the target lens X The relation 95.2 ≥ Vd is satisfied. X ≥60.

0.

7. The low-magnification, large-target-area telecentric lens according to claim 5, characterized in that, The first lens group includes the target lens; And / or, the second lens group includes the target lens; The target lens has positive optical power and is any one of a meniscus lens, a biconvex lens, or a plano-convex lens.

8. The low-magnification, large-target-area telecentric lens according to claim 2, characterized in that, The second lens group includes at least an eighth lens, a ninth lens, a tenth lens, and an eleventh lens arranged from the object side to the image side; the eighth lens has negative optical power, the ninth lens has positive optical power, and the eighth lens and the ninth lens are cemented together to form a cemented lens.

9. The low-magnification, large-target-area telecentric lens according to any one of claims 1-8, characterized in that, The magnification of the low-magnification, large-target-area telecentric lens is 0.

33. And / or, the depth of field of the low-magnification, large-area telecentric lens is 4.4 mm.

10. A camera module, characterized in that, include: The low-magnification, large-target-area telecentric lens according to any one of claims 1 to 12; A photosensitive element is disposed on the image side of the low-magnification, large-target-area telecentric lens.

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