High-power coaxial telecentric lens and camera module

Abstract

Embodiments of the present application provide a high-magnification coaxial telecentric lens and a camera module. The high-magnification coaxial telecentric lens comprises, in order from the object side to the image side, a first lens group, a light splitting prism, a diaphragm, a second lens group and a third lens group. The first lens group comprises a first lens, a second lens, a third lens, a fourth lens and a fifth lens. The second lens group comprises a sixth lens and a seventh lens. The third lens group comprises an eighth lens and a ninth lens. The light splitting prism is provided with a coaxial light source on one side. The first lens, the third lens, the fifth lens, the sixth lens and the ninth lens all have positive refractive powers. The second lens, the fourth lens, the seventh lens and the eighth lens all have negative refractive powers. The first lens group comprises a first cemented lens. The focal length f J01 of the first cemented lens and the focal length f1 of the first lens group satisfy the relationship: 45 < f J01 / f1 < 55. The high-magnification coaxial telecentric lens achieves the purposes of high magnification, large numerical aperture and high imaging quality.

Description

Technical Field

[0001] This application relates to the field of industrial coaxial telecentric lens technology, and in particular to a high-magnification coaxial telecentric lens and camera module. Background Technology

[0002] With increasingly stringent demands for microscopic defect identification and material penetration imaging in industrial inspection, coaxial telecentric lenses, with their high precision, low distortion, and magnification stability, are widely used in the inspection of semiconductor wafers, photovoltaic panels, and high-precision metal parts. However, traditional coaxial telecentric lenses designed for the visible light band are limited by their physical wavelength characteristics when facing scenarios such as internal inspection of silicon-based materials and imaging of multilayer transparent media. They are unable to effectively penetrate specific materials. At the same time, when inspection requirements extend to micron- or even submicron-level defects, lenses with conventional magnification have insufficient numerical aperture and resolution, making it difficult to distinguish minute features. Furthermore, at high magnification, they are more prone to problems such as difficulty in infrared chromatic aberration correction and increased stray light. Summary of the Invention

[0003] The embodiments of this application provide a high-magnification coaxial telecentric lens and camera module that can balance high magnification, large numerical aperture, and high imaging quality.

[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 high-magnification coaxial telecentric lens, comprising a first lens group, a beam splitter, an aperture stop, a second lens group, and a third lens group arranged from the object side to the image side. The first lens group includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged from the object side to the image side. The second lens group includes a sixth lens and a seventh lens arranged from the object side to the image side. The third lens group includes an eighth lens and a ninth lens arranged from the object side to the image side. A coaxial light source is provided on one side of the beam splitter, and the optical axis of the coaxial light source intersects the optical axis of the high-magnification coaxial telecentric lens. The first lens, the third lens, the fifth lens, the sixth lens, and the ninth lens all have positive optical power, and the second lens, the fourth lens, the seventh lens, and the eighth lens all have negative optical power. The first lens group includes a first cemented lens, and the focal length f of the first cemented lens is... J01 The focal length f1 of the first lens group satisfies the following relationship: 45 <f J01 / f1<55; where, as stated.

[0005] In some feasible ways, the second lens, the third lens, and the fourth lens are cemented together to form the first cemented lens.

[0006] In some realizable ways, the focal length f1 of the first lens and the focal length f of the high-magnification coaxial telecentric lens satisfy the relational expression: 8.5 < f1 / f < 9.5; and / or, the focal length f5 of the fifth lens and the focal length f of the high-magnification coaxial telecentric lens satisfy the relational expression: 6.5 < f5 / f < 7.5.

[0007] In some realizable ways, the radius of curvature R1 of the object side of the first lens and the focal length f1 of the first lens satisfy the relational expression: 1.8 < R1 / f1 < 2.5.

[0008] In some realizable ways, the combined focal length f of the sixth lens and the seventh lens G2 and the focal length f of the high-magnification coaxial telecentric lens satisfy the relational expression: -4.5 < f G2 / f < -4.

[0009] In some realizable ways, the sixth lens and the seventh lens are glued together to form a glued lens; and / or, the eighth lens and the ninth lens are glued together to form a glued lens.

[0010] In some realizable ways, the focal length f of the second lens group G2 and the focal length f of the third lens group G3 satisfy the relational expression: 2 < f G2 / f G3 < 2.5.

[0011] In some realizable ways, the Abbe number vd6 of the sixth lens and the Abbe number vd7 of the seventh lens satisfy the relational expression: |vd6 - vd7| > 60.

[0012] In some realizable ways, the focal length f9 of the ninth lens and the refractive index Nd9 of the ninth lens satisfy the relational expression: 3.5 < f9 / Nd9 < 4.5, Nd9 > 1.95.

[0013] In some realizable ways, the optical axis of the coaxial light source is perpendicular to the optical axis of the high-magnification coaxial telecentric lens; and / or, the beam splitter prism has a beam splitting surface, and the transmittance t and reflectance r of the beam splitting surface satisfy the relational expression: t:r = 1:1.

[0014] In some realizable ways, the working wavelength band of the high-magnification coaxial telecentric lens is 0.94 μm - 1.55 μm.

[0015] In a second aspect, an embodiment of the present application provides a camera module, including the high-magnification coaxial telecentric lens described in the first aspect and a photosensitive element, and the photosensitive element is disposed on the image side of the high-magnification coaxial telecentric lens.

[0016] The high-magnification coaxial telecentric lens provided in this application includes nine lenses: a first lens group, a second lens group, and a third lens group. A beam splitter is positioned before the aperture stop. By rationally allocating the optical power of the nine lenses, aberrations can be well balanced. In particular, the third lens group effectively balances the aberrations introduced by the beam splitter. Furthermore, the first lens, located first 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 but also, through pre-convergence of the light, [further benefits are achieved]. This allows light rays to pass through the high-magnification coaxial telecentric lens in parallel, effectively controlling telecentricity. Furthermore, when the focal length of the first cemented lens and the focal length of the first lens group satisfy the aforementioned relationship, the height of the light rays in front of the aperture stop can be effectively controlled to prevent drastic fluctuations due to the addition of the cemented lens. This effectively reduces the deflection angle of the light rays at the edge aperture. Thus, not only can spherical aberration be further balanced, but it also helps to balance high magnification and large numerical aperture, achieving a balance between high magnification, large numerical aperture, and high image quality, while reducing sensitivity to processing and assembly errors and improving yield. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of the structure of the high-magnification coaxial telecentric lens provided in Embodiment 1 of this application; Figure 2 This is the MTF vs Field diagram of the high-magnification coaxial telecentric lens provided in Embodiment 1 of this application; Figure 3 This is a field curvature diagram of a high-magnification coaxial telecentric lens provided in Embodiment 1 of this application; Figure 4 The distortion diagram of the high-magnification coaxial telecentric lens provided in Embodiment 1 of this application; Figure 5 The 0.7 aperture chromatic focus shift diagram of the high-magnification coaxial telecentric lens provided in Embodiment 1 of this application Figure 6 Simulation diagram of imaging plane illumination of a high-magnification coaxial telecentric lens provided in Embodiment 1 of this application; Figure 7 This is a schematic diagram of the structure of the high-magnification coaxial telecentric lens provided in Embodiment 2 of this application; Figure 8 This is the MTF vs Field diagram of the high-magnification coaxial telecentric lens provided in Embodiment 2 of this application; Figure 9 This is a field curve diagram of the high-magnification coaxial telecentric lens provided in Embodiment 2 of this application; Figure 10 This is a distortion image of the high-magnification coaxial telecentric lens provided in Embodiment 2 of this application; Figure 11 The 0.7 aperture chromatic focus shift diagram of the high-magnification coaxial telecentric lens provided in Embodiment 1 of this application Figure 12 Simulation diagram of imaging plane illumination of a high-magnification coaxial telecentric lens provided in Embodiment 1 of this application.

[0018] The following are the labeling elements in the figure: First lens group G1; Second lens group G2; Third lens group G3; First cemented lens J01; Second cemented lens J02; Third cemented lens J03; 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; Aperture stop STO; Imaging plane IMAGE; Protective film CG. Detailed Implementation

[0019] For ease of understanding, the English abbreviations and related technical terms used in the embodiments of this application will be explained and described below.

[0020] 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 high-magnification coaxial telecentric lens to deflect light rays.

[0021] A lens or lens group with positive optical power, having a positive focal length, and having the effect of converging light.

[0022] A lens or lens group with negative optical power has a negative focal length and has the effect of diverging light.

[0023] 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.

[0024] The effective focal length (EFL) of a lens refers to the distance from the center of the lens to the focal point.

[0025] The combined focal length is the combination of the focal lengths of the individual lenses in a lens group.

[0026] 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.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] 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.

[0031] The focal point is the point where parallel light rays converge after being refracted by a lens or lens group.

[0032] 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.

[0033] 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.

[0034] 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.

[0035] 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.

[0036] 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.

[0037] like Figure 1 As shown in the figure, this application embodiment provides a camera module, which includes a high-magnification coaxial telecentric lens and a photosensitive element (not shown in the figure), with the photosensitive element located on the image side of the high-magnification coaxial telecentric lens.

[0038] The working principle of this camera module is as follows: the light reflected from the subject passes through a high-magnification coaxial 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.

[0039] Among them, the photosensitive element (also known as the image sensor) is located in, for example, Figure 1 The 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.

[0040] Among them, the high-magnification coaxial telecentric lens 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 high-magnification coaxial telecentric lens, the magnification is achieved by the movement of part of the lens group, and a clear image is formed on the focal plane within different object distances. The image of the scene is then recorded by a photosensitive element located on the focal plane.

[0041] like Figure 1 As shown, a protective film (CG) is usually provided on the photosensitive element. This serves to support and protect the photosensitive element.

[0042] like Figure 1 As shown, this application embodiment provides a high-magnification coaxial telecentric lens, including a first lens group G1, a beam splitter P, an aperture stop, a second lens group G2, and a third lens group G3 arranged from the object side to the image side. The first lens group G1 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5 arranged from the object side to the image side. The second lens group G2 includes a sixth lens L6 and a seventh lens L7 arranged from the object side to the image side. The third lens group G3 includes an eighth lens L8 and a ninth lens L9 arranged from the object side to the image side. A coaxial light source is provided on one side of the beam splitter P, and the optical axis of the coaxial light source intersects with the optical axis of the high-magnification coaxial telecentric lens.

[0043] The aforementioned beam-splitting prism P primarily functions to split light. A coaxial light source is placed on the light-ingress surface of beam-splitting prism P. After passing through the light-ingress surface of beam-splitting prism P, the light path is deflected by 90° by beam-splitting prism P, achieving a coaxial illumination effect. It should be noted that the aforementioned beam-splitting prism P can be a non-polarizing beam-splitting prism, which can be composed of two right-angle prisms cemented together.

[0044] The angle between the optical axis of the aforementioned coaxial light source and the optical axis of the high-magnification coaxial telecentric lens is between 85° and 95°. In other words, the optical axis of the coaxial light source is perpendicular or substantially perpendicular to the optical axis of the high-magnification coaxial telecentric lens.

[0045] The first lens L1, third lens L3, fifth lens L5, sixth lens L6, and ninth lens L9 all have positive optical power, while the second lens L2, fourth lens L4, seventh lens L7, and eighth lens L8 all have negative optical power. By rationally allocating the optical power of each lens in the high-magnification coaxial telecentric lens, aberrations can be effectively corrected, thereby improving image quality. Simultaneously, the positive optical power of the first lens L1 facilitates the convergence of light rays over a wider range. This not only effectively gathers light rays from a large field of view but also, through pre-convergence, ensures that the light rays pass parallel through the high-magnification coaxial telecentric lens, thus effectively controlling telecentricity.

[0046] The first lens group G1 mentioned above includes a first cemented lens J01, wherein any two or three consecutive lenses in the first lens group G1 are cemented together to form the first cemented lens J01.

[0047] refer to Figure 1 The second lens L2, the third lens L3, and the fourth lens L4 are cemented together to form the first cemented lens J01. This not only helps reduce tolerance sensitivity but also simplifies the assembly process, thereby reducing the sensitivity to processing and assembly errors and improving the yield rate. Of course, the first lens group G1 can also be formed by cementing the second lens L2 and the third lens L3 together, or by cementing the third lens L3 and the fourth lens L4 together. Alternatively, the first lens group G1 can also include two first cemented lenses J01; no specific limitation is made here.

[0048] Based on this, the focal length f of the first cemented lens J01 J01 The ratio of the focal length f1 of the first lens group G1 to the focal length f1 is f J01 / f1 is used to precisely control the optical power distribution, with the core objective of balancing aberrations. If this ratio is too large, the optical power of the first lens L1 will be too strong, introducing serious problems such as spherical aberration and chromatic aberration, which is detrimental to the aberration correction of subsequent lenses. If the ratio is too small, the optical power of the first lens L1 will be too weak, which is not conducive to achieving large target surfaces and large numerical apertures (NA). When the ratio f...J01 / f1 satisfies the relation: 45 <f J01 When f1 < 55, the height of the light in front of the aperture can be effectively controlled so that it does not fluctuate drastically due to the addition of the cemented lens. This effectively reduces the deflection angle of the light at the edge aperture. In this way, not only can spherical aberration be further balanced, but it is also beneficial to take into account both high magnification and large numerical aperture. This achieves a balance between high magnification, large numerical aperture and high imaging quality, as well as reducing the sensitivity to processing and assembly errors and improving the yield rate.

[0049] In some implementations, the transmittance t and reflectance r of the beam-splitting surface of the beam-splitting prism P satisfy the relationship: t:r = 1:1.

[0050] At high magnification, even the slightest stray light can severely affect image contrast. If the reflectivity is too high, stronger secondary reflections may occur inside the beam splitter prism P, creating "ghosting" that interferes with imaging. A t:r ratio of 1:1, this balanced design, helps minimize this risk of internal reflection through coating and structural design, thereby reducing stray light and ghosting.

[0051] It should be noted that the operating wavelength of the high-magnification coaxial telecentric lens is 0.94μm-1.55μm.

[0052] In some feasible implementations, the focal length f1 of the first lens L1 and the focal length f of the high-magnification coaxial telecentric lens satisfy the relationship: 8.5 <f1 / f<9.5。

[0053] By appropriately selecting the focal length f1 of the first lens L1 and the focal length f of the high-magnification coaxial telecentric lens, when the above relationship is satisfied, "at a large numerical aperture NA, the object-side beam enters the high-magnification coaxial telecentric lens at a large angle, which is equivalent to using a 'gentle curved surface' to slowly converge the edge rays. This not only minimizes the amount of aberrations and effectively corrects spherical aberration and coma, but also effectively controls the aperture. Based on this, in conjunction with the beam splitter P, the low-light power ensures that the light rays remain approximately parallel after passing through the first lens L1. This provides the subsequent embedded beam splitter P with near-parallel light incidence conditions, effectively reducing astigmatism introduced by the prism."

[0054] In some feasible implementations, the focal length f5 of the fifth lens L5 satisfies the relationship f with the focal length f of the high-magnification coaxial telecentric lens: 6.5 <f5 / f<7.5。

[0055] The above-mentioned fifth lens L5 undertakes the main refraction task. The fifth lens L5 is located at the end of the first lens group G1 (close to the aperture STOP), and at this time the light beam diameter has been narrowed. It is responsible for "relaying" the light rays slowly converged by the front group and precisely converging them towards the center of the aperture STOP. At the same time, the fifth lens L5 and the first lens L1 form a weak optical power pair. The negative spherical aberration generated by the first lens L1 (the marginal light converges slowly) is offset by the appropriate positive spherical aberration generated by the fifth lens L5 (the marginal light converges quickly). This "one in front and one behind, one slow and one fast" combination is the key to ensuring that the spherical aberration is corrected to the diffraction limit under a large numerical aperture NA, and it plays a very good role in balancing the aberration of the front and rear groups.

[0056] In some realizable ways, the radius of curvature R1 of the object side surface of the first lens L1 and the focal length f1 of the first lens satisfy the relationship: 1.8 < R1 / f1 < 2.5. That is to say, the ratio R1 / f1 is approximately equal to 2. This means that this surface has a moderate degree of curvature. If the ratio R1 / f1 is less than 1.8, the surface of the object side of the first lens L1 is too curved, which will cause the refraction angle of the marginal light rays to be too large, leading to high-order spherical aberration that is difficult to correct; if the ratio R1 / f1 is greater than 2.5, the surface of the object side of the first lens L1 is too flat, then it cannot provide enough refractive power to receive large-NA incident light, forcing the subsequent lenses to bear an excessive burden.

[0057] When the ratio R1 / f1 satisfies the above relationship, not only can the high-order aberration and processability be reduced, but also, in a system with a coaxial light source, this curvature range can effectively prevent the object side surface of the first lens L1 from reflecting the illumination light back to the beam splitter prism P, thereby reducing the risk of ghost images and effectively suppressing stray light.

[0058] Reference Figure 1 , in some realizable ways, the sixth lens L6 and the seventh lens L7 are glued together to form a glued lens, that is, the second glued lens J02; the eighth lens L8 and the ninth lens L9 are glued together to form a glued lens, that is, the third glued lens J03. It should be noted that the high-magnification coaxial telecentric lens may also only include the second glued lens J02 or the third glued lens J03, and no specific limitation is made here.

[0059] In some realizable ways, the combined focal length f G2 of the sixth lens L6 and the seventh lens L7 and the focal length f of the high-magnification coaxial telecentric lens satisfy the relationship: -4.5 < f G2 / f < -4.

[0060] By properly configuring the focal lengths of the sixth lens L6 and the seventh lens L7, and when the focal length of the second lens group G2 satisfies the above-mentioned condition, the stray light caused by the reflection of the beam splitter P can converge at a point far away from the image plane after passing through the second lens group G2. This ensures that the high-magnification coaxial telecentric lens will not produce ghosting or stray light problems at low light intensity, which is beneficial for achieving high resolution, uniform illumination, and uniform image quality.

[0061] In some feasible ways, the focal length f of the second lens group G2 G2 The focal length f of the third lens group G3 G3 Satisfying the relation: 2 <f G2 / f G3 <2.5.

[0062] By properly configuring the focal length f of the second lens group G2 G2 The focal length f of the third lens group G3 G3 When the ratio satisfies the above relationship, the overall beam can maintain smooth light when propagating in the second lens group G2 and the third lens group G3, and will not produce a large light incident angle on the lens surface. This can reduce the high-level phase difference caused by the large-aperture wide beam at the front end near the object side, and improve the overall tolerance performance.

[0063] In some feasible implementations, the Abbe number vd6 of the sixth lens L6 and the Abbe number vd7 of the seventh lens L7 satisfy the relationship: |vd6-vd7|>60. Thus, the materials of the sixth lens L6 and the seventh lens L7 have significantly different dispersion characteristics, which can effectively compensate for the axial and magnification chromatic aberrations introduced by the first lens group G1 and the beam splitter P, thereby strongly eliminating chromatic aberration.

[0064] In some feasible implementations, the focal length f9 and refractive index Nd9 of the ninth lens L9 satisfy the relationship: 3.5 <f9 / Nd9<4.5,Nd9>1.95。

[0065] The last lens in a high-magnification coaxial telecentric lens, located near the image plane, is a high-refractive-index positive lens. This effectively focuses large-aperture light, reducing the lens's aperture, cost, and overall size. Simultaneously, it efficiently converges the light beam to the image plane while minimizing advanced astigmatism.

[0066] It should be noted that the "low magnification" in the above-mentioned high-magnification coaxial telecentric lens refers to lenses with a magnification greater than 1.0. Generally, high-magnification telecentric lenses have a smaller field of view, especially the higher the magnification, the smaller the coverage area is to improve detection accuracy. This high-magnification coaxial telecentric lens is illustrated using a 6X magnification as an example.

[0067] like Figure 1 A schematic diagram of the structure of a high-magnification coaxial telecentric lens according to Embodiment 1 of this application is shown. This high-magnification coaxial telecentric lens includes a first lens group G1, a beam splitter P, an aperture stop, a second lens group G2, and a third lens group G3 arranged from the object side to the image side. The first lens group G1 includes a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, and a fifth lens L5 arranged from the object side to the image side. The second lens group G2 includes a sixth lens L6 and a seventh lens L7 arranged from the object side to the image side. The third lens group G3 includes an eighth lens L8 and a ninth lens L9 arranged from the object side to the image side. The second lens L2, the third lens L3, and the fourth lens L4 are cemented together to form a first cemented lens J01; the sixth lens L6 and the seventh lens L7 are cemented together to form a second cemented lens J02; and the eighth lens L8 and the ninth lens L9 are cemented together to form a third cemented lens J03. A coaxial light source is provided on one side of the beam splitter P, and the optical axis of the coaxial light source is perpendicular to the optical axis of the high-magnification coaxial telecentric lens.

[0068] Tables 1a to 1c provide the specific parameter values ​​for each lens of the high-magnification coaxial telecentric lens in one of the optional embodiments of Embodiment 1 of this application.

[0069]

[0070] 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 STOP in the "Thickness" parameter series is the distance on the optical axis from the center of the stop STOP to the object side of the next lens. "IMAGE" corresponds to the imaging plane of a high-magnification coaxial telecentric lens, which in this embodiment refers to the following: Figure 1 The image plane on the far right of the high-magnification coaxial telecentric lens shown. The value of "STOP" at the thickness in Table 1a represents the distance between the STOP and the sixth lens L6.

[0071] The conjugate distance of the high-magnification coaxial telecentric lens in this embodiment is: OI = 296.4 mm; focal length f = 10.6 mm; magnification 6X.

[0072] The positive and negative values ​​of the optical power of each lens in the high-magnification coaxial telecentric lens of Example 1 are shown in Table 1b.

[0073]

[0074] It should be noted that the "+" and "-" in Table 1b represent the positive and negative optical power of each lens in the high-magnification coaxial telecentric lens of Example 1. "+" indicates that the lens has positive optical power; "-" indicates that the lens has negative optical power.

[0075] The concavity or convexity of the object side or image side of each lens in the high-magnification coaxial telecentric lens in Example 1 at the optical axis is shown in Table 1c.

[0076]

[0077] 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 high-magnification coaxial 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.

[0078] Combination Figure 1 The diagram shows the structure of the high-magnification coaxial telecentric lens in Example 1, and Tables 1a to 1c show the main parameters of the high-magnification coaxial telecentric lens in Example 1, as well as the concavity and convexity of each lens at the optical axis. Simulations were used to obtain simulation diagrams of the MTF vs. Field, field curvature, distortion, focus shift, and imaging plane illumination of the high-magnification coaxial telecentric lens in Example 1.

[0079] The MTF vs Field plot is a graph reflecting the contrast (fidelity) of a high-magnification coaxial telecentric lens. A higher value on the ordinate of the MTF vs Field plot indicates better fidelity and higher resolution from the medium-to-long telephoto high-magnification coaxial telecentric lens. Figure 2It can be seen that the high-magnification coaxial telecentric lens provided in this embodiment has an overall field-of-view contrast greater than 0.68 at 10 lp / mm.

[0080] The field curvature diagram above visually illustrates the degree of image plane curvature, where the horizontal axis represents the distance from the actual image plane and the vertical axis represents the true field of view height.

[0081] The distortion graph above represents the percentage distortion of a high-magnification coaxial telecentric lens as the field of view changes, where the horizontal axis represents the percentage distortion and the vertical axis represents the true field of view height.

[0082] from Figure 3 and Figure 4 It can be seen that the field curvature correction of the high-magnification coaxial telecentric lens provided in this embodiment is within ±0.4mm, and the distortion correction is within ±0.08%.

[0083] Figure 5 This is a 0.7 aperture chromatic focus shift diagram of the high-magnification coaxial telecentric lens provided in Embodiment 1 of the present invention, demonstrating the multicolor light focus correction capability of the lens in this embodiment. From Figure 5 It can be seen that the high-magnification coaxial telecentric lens provided in this embodiment has a color focus shift of less than 95 μm in the short-wave infrared 0.94 μm-1.55 μm band.

[0084] Figure 6 This is a simulation diagram of the imaging surface illumination provided in Embodiment 1 of the present invention, demonstrating the coaxial illumination uniformity capability of the high-magnification coaxial telecentric lens of this embodiment. Figure 6 It can be seen that the highest energy of the image surface IMA is 7.3E-08w / mm^2, the lowest energy is 3.9E-08w / mm^2, and the uniformity of the image surface reaches more than 50%.

[0085] The above descriptions of simulation diagrams such as MTF vs Field plots, field curvature plots, distortion plots, focus shift plots, and imaging surface illumination simulation plots are the same as those in other embodiments, and will not be repeated below.

[0086] Figures 2 to 6 This demonstrates that, at a magnification of 6X, the high-magnification coaxial telecentric lens in this embodiment exhibits minimal reduction in image fidelity and edge quality. This indicates that the high-magnification coaxial telecentric lens produces clear images with minimal distortion in the short-wave infrared 0.94μm-1.55μm band.

[0087] Figure 7A schematic diagram of the high-magnification coaxial telecentric lens of Embodiment 2 is shown. The main difference between the high-magnification coaxial telecentric lens of Embodiment 2 and the high-magnification coaxial telecentric lens of Embodiment 1 is that the parameters and conditions satisfied by each lens in the high-magnification coaxial telecentric lens are different, as are the concavity and convexity of the object side or image side of each lens at the optical axis.

[0088] Tables 2a to 2c provide the specific parameter values ​​for each lens of the high-magnification coaxial telecentric lens in one of the optional embodiments of Embodiment 2 of this application.

[0089]

[0090] In this embodiment, the conjugate distance of the high-magnification coaxial telecentric lens is: OI = 296.4 mm; focal length f = 10.5 mm; and magnification is 6X.

[0091] The positive and negative values ​​of the optical power of each lens in the high-magnification coaxial telecentric lens of Example 2 are shown in Table 2b.

[0092]

[0093] The concavity or convexity of the object side or image side of each lens in the high-magnification coaxial telecentric lens of Example 2 at the optical axis is shown in Table 2c.

[0094]

[0095] Combination Figure 7 The given schematic diagram of the high-magnification coaxial telecentric lens in Embodiment 2, and Tables 2a to 2c show the main parameters of the high-magnification coaxial telecentric lens in Embodiment 2, as well as the concavity and convexity of each lens at the optical axis.

[0096] from Figures 8 to 12 This demonstrates that, at a magnification of 6X, the high-magnification coaxial telecentric lens in this embodiment exhibits minimal reduction in image fidelity and edge quality. This indicates that the high-magnification coaxial telecentric lens produces clear images with minimal distortion in the short-wave infrared 0.94μm-1.55μm band.

[0097] Table 3 gives the numerical values ​​corresponding to the relationships satisfied by the high-magnification coaxial telecentric lenses in the two embodiments above.

[0098]

[0099] Note: The following annotations explain the relationship between the high-magnification coaxial telecentric lenses in the various embodiments: f is the focal length of the high-magnification coaxial telecentric lens; f G1 The focal length of the first lens group G1 of the high-magnification coaxial telecentric lens; f G2 The focal length of the second lens group G2 of the high-magnification coaxial telecentric lens; f G3 The focal length of the third lens group G3 in the high-magnification coaxial telecentric lens; f1 is the focal length of the first lens L1 in the first lens group G1; The focal length of the first cemented lens; The focal length of the second cemented lens; The focal length of the third cemented lens; R1 is the radius of curvature of the object-side surface of the first lens L1.

[0100] In summary, the high-magnification coaxial telecentric lens in this embodiment has a magnification of 6X and an operating wavelength of 0.94μm-1.55μm, both of which ensure clear imaging, i.e., good consistency in distortion and chromatic aberration over a large depth of field. This high-magnification coaxial telecentric lens combines micron-level resolution, low distortion, and excellent aberration suppression capabilities in the short-wave infrared band. At high magnification, the high-magnification coaxial telecentric lens can more clearly reveal the edge details and internal structure of hidden defects, significantly reducing false positives and false negatives. With the continuous improvement of the requirements for detection accuracy and material adaptability in Industry 4.0, this high-magnification short-wave infrared coaxial telecentric lens provides an advanced optical solution with high penetration, high resolution, and uniform illumination for high-end semiconductor packaging, photovoltaic microcrack detection, composite material analysis, and special precision machining.

[0101] 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 high-magnification coaxial telecentric lens, characterized in that, It includes a first lens group, a beam splitter, an aperture, a second lens group, and a third lens group arranged from the object side to the image side. The first lens group includes a first lens, a second lens, a third lens, a fourth lens, and a fifth lens arranged from the object side to the image side. The second lens group includes a sixth lens and a seventh lens arranged from the object side to the image side. The third lens group includes an eighth lens and a ninth lens arranged from the object side to the image side. A coaxial light source is provided on one side of the beam splitter, and the optical axis of the coaxial light source intersects with the optical axis of the high-magnification coaxial telecentric lens; The first lens, the third lens, the fifth lens, the sixth lens, and the ninth lens all have positive optical power, while the second lens, the fourth lens, the seventh lens, and the eighth lens all have negative optical power. The first lens group includes a first cemented lens, the focal length of which is f. J01 The focal length f1 of the first lens group satisfies the following relationship: 45 <f J01 / f1<55; The first cemented lens is formed by cementing any two or three consecutive lenses in the first lens group together.

2. The high-magnification coaxial telecentric lens according to claim 1, characterized in that, The second lens, the third lens, and the fourth lens are cemented together to form the first cemented lens.

3. The high-magnification coaxial telecentric lens according to claim 1, characterized in that, The focal length f1 of the first lens and the focal length f of the high-magnification coaxial telecentric lens satisfy the following relationship: 8.5 <f1 / f<9.5; And / or, the focal length f5 of the fifth lens and the focal length f of the high-magnification coaxial telecentric lens satisfy the relationship: 6.5 <f5 / f<7.5。 4. The high-magnification coaxial telecentric lens according to claim 1, characterized in that, The radius of curvature R1 of the object-side surface of the first lens and the focal length f1 of the first lens satisfy the following relationship: 1.8 <R1 / f1<2.5。 5. The high-magnification coaxial telecentric lens according to claim 1, characterized in that, The combined focal length f of the sixth lens and the seventh lens G2 The focal length f of the high-magnification coaxial telecentric lens satisfies the following relationship: -4.5 <f G2 / f<-4.

6. The high-magnification coaxial telecentric lens according to claim 1, characterized in that, The sixth lens and the seventh lens are cemented together to form a cemented lens; And / or, the eighth lens and the ninth lens are cemented together to form a cemented lens.

7. The high-magnification coaxial telecentric lens according to claim 1, characterized in that, The focal length f of the second lens group G2 and the focal length f of the third lens group G3 Satisfying the relation: 2 <f G2 / f G3 <2.

5.

8. The high-magnification coaxial telecentric lens according to claim 1, characterized in that, The Abbe number vd6 of the sixth lens and the Abbe number vd7 of the seventh lens satisfy the relationship: |vd6-vd7|>60.

9. The high-magnification coaxial telecentric lens according to any one of claims 1-8, characterized in that, The focal length f9 and the refractive index Nd9 of the ninth lens satisfy the following relationship: 3.5 <f9 / Nd9<4.5,Nd9>1.95。 10. The high-magnification coaxial telecentric lens according to any one of claims 1-8, characterized in that, The optical axis of the coaxial light source is perpendicular to the optical axis of the high-magnification coaxial telecentric lens; And / or, the beam-splitting prism has a beam-splitting surface, and the transmittance t and reflectance r of the beam-splitting surface satisfy the relationship: t:r=1:

1.

11. The high-magnification coaxial telecentric lens according to any one of claims 1-8, characterized in that, The high-magnification coaxial telecentric lens operates in the wavelength range of 0.94μm-1.55μm.

12. A camera module, characterized in that, include: The high-magnification coaxial telecentric lens according to any one of claims 1 to 11; A photosensitive element is disposed on the image side of the high-magnification coaxial telecentric lens.

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