Variable line width line spot system based on a cylindrical lens array

Abstract

The application provides a variable line width line light spot system based on a column lens array, which is compact in structure, has the functions of variable line width and excellent light spot uniformity, and is suitable for various detection distance requirement scenes; a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a column lens array are sequentially arranged along an optical axis from an object side to an image side; the first lens serves as a first lens group; the second lens, the third lens and the fourth lens are combined to form a second lens group; the fifth lens serves as a third lens group; and the first lens group, the second lens group and the third lens group are combined to form a zoom system; the first lens group, the third lens group and the column lens array are fixed in position; and the second lens group between the first lens group and the third lens group moves along the optical axis in opposite directions or in the same direction to realize focal length change.

Description

Technical Field

[0001] This invention relates to the field of laser optics technology, specifically to a variable linewidth line spot system based on a cylindrical lens array. Background Technology

[0002] Machine vision is an interdisciplinary field encompassing artificial intelligence, neurobiology, psychophysics, image processing, and new energy. In recent years, due to the maturity and improvement of computer technology, especially multimedia technology, digital image processing and analysis theories, and the rapid development of large-scale integrated circuits, machine vision technology has been widely applied, bringing significant economic and social benefits. For example, in the field of new energy, the production process of solar cells includes processes such as loading, cleaning, wire forming, and etching of raw silicon wafers. Each process requires quality inspection of the cells. Simultaneously, to improve silicon utilization, the thickness of crystalline silicon is continuously decreasing, but this also increases the risk of wafer damage. Therefore, wafer quality inspection is crucial in the production process. From solar cell manufacturing to welding, concentric circles, cracks, fragments, and dirt must be inspected to ensure luminous efficiency.

[0003] Machine vision provides an effective means of non-contact inspection for solar cell inspection. Among them, non-contact inspection based on infrared lasers can achieve high-quality silicon wafer inspection. This inspection method uses the principle of photoluminescence to induce light intensity differences, and then determines the location of defects by the intensity differences in the images captured by the camera. Therefore, the laser light source has become an indispensable part of the inspection process. Common lasers have a fixed working distance, but when used for solar cell inspection, a fixed working distance will limit the working environment. Therefore, flexible working distance, i.e., variable laser focus position, can make the laser applicable to various inspection distance requirements and improve the utilization rate of the laser. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a variable linewidth line spot system based on a cylindrical lens array. This system has a compact structure, variable linewidth, and excellent spot uniformity, thus adapting to various detection distance requirements.

[0005] The present invention adopts the following technical solution: a variable linewidth and line spot system based on a cylindrical lens array, characterized in that it comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a cylindrical lens array arranged sequentially along the optical axis from the object side to the image side. The first lens serves as a first lens group, the second, third, and fourth lenses are combined to form a second lens group, and the fifth lens serves as a third lens group. The first, second, and third lens groups are combined to form a zoom system. The positions of the first, third, and cylindrical lens arrays are fixed, and the second lens group located between the first and third lens groups moves towards or away from each other along the optical axis to achieve focal length variation.

[0006] Furthermore, the first lens group and the second lens group satisfy the following relationship: ; in, It is the focal length of the first lens group. It is the focal length of the second lens group; Furthermore, the first lens group has negative refractive power; the second lens group has positive refractive power, the second lens has positive refractive power, the third lens has negative refractive power, the fourth lens has positive refractive power, and the third lens group has positive refractive power; Furthermore, the cylindrical lens array is composed of at least 7 sub-cylindrical lenses arranged in an array; and the diameter of the light spot incident on the cylindrical lens array is greater than the arrangement period length of the at least 7 sub-cylindrical lenses; Furthermore, the object plane of the first lens is a plane, and the image plane is a concave arc surface; The object plane of the second lens is a convex arc surface, and the image plane is a concave arc surface; The object plane of the third lens is a concave arc surface, and the image plane is a concave arc surface; The object plane of the fourth lens is a concave arc surface, and the image plane is a convex arc surface; The object plane of the fifth lens is a plane, and the image plane is a convex arc. Furthermore, the first lens, second lens, third lens, fourth lens, and fifth lens are all made of transparent optical materials; Furthermore, the radius of curvature of the image plane of the first lens is 25.75 mm, and the thickness of the first lens is 3.5 mm; The second lens has an object plane radius of curvature of 32.14 mm and an image plane radius of curvature of 82.2 mm; the second lens has a thickness of 3.6 mm; and the distance between the image plane of the first lens and the object plane of the second lens is 10~28 mm. The object plane of the third lens has a radius of curvature of -77.86 mm, and the image plane has a radius of curvature of 77.86 mm; the thickness of the third lens is 3.5 mm, and the distance between the image plane of the second lens and the object plane of the third lens is 2.0298 mm. The fourth lens has an object plane radius of curvature of -82.20 mm and an image plane radius of curvature of -32.14 mm; the fourth lens has a thickness of 3.6 mm; and the distance between the image plane of the third lens and the object plane of the fourth lens is 6.5589 mm. The radius of curvature of the image plane of the fifth lens is -38.8 mm, the thickness of the fifth lens is 7.5 mm, and the interval between the image plane of the fourth lens and the object plane of the fifth lens is 3.5~19.5 mm. The object plane of the cylindrical lens array has a radius of curvature of 2.5 mm, the thickness of the cylindrical lens array is 2 mm, and the distance between the image plane of the fifth lens and the object plane of the cylindrical lens array is 20 mm.

[0007] The beneficial effects of this invention are that the zoom system can expand the incident light wave, so that the size of the incident light wave matches the aperture of the cylindrical lens array. The second lens group moves towards or away from the first lens group and the third lens group along the optical axis, so that the incident light wave can form a focused spot at different focusing positions after passing through the cylindrical lens array, thereby modulating the linewidth of the line spot, adapting to various detection distance requirements and having good application value. Attached Figure Description

[0008] Figure 1 This is a schematic diagram of the structure for forming a linear light spot according to the present invention; Figure 2 This is a schematic diagram of the linear light spot structure formed by the cylindrical lens array according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the close-range focusing structure in an embodiment of the present invention; Figure 4 This is a schematic diagram of the mid-to-long-distance focusing structure in an embodiment of the present invention; Figure 5 This is a schematic diagram of the long-distance focusing structure in an embodiment of the present invention; Figure 6 This is a grayscale image of a close-range light spot in an embodiment of the present invention; Figure 7 This is a grayscale image of a medium-to-long-distance light spot in an embodiment of the present invention; Figure 8 This is a grayscale image of a long-distance light spot in an embodiment of the present invention; Figure 9 This is a schematic diagram of the linewidth variation of the light spot provided in an embodiment of the present invention; Figure 10This is a schematic diagram of the focal length variation of the line spot provided in an embodiment of the present invention. Detailed Implementation

[0009] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it.

[0010] The term "comprising" and its variations as used in this invention are open-ended, meaning "including but not limited to". The term "based on" means "at least partially based on". The term "one embodiment" means "at least one embodiment".

[0011] It should be noted that the concepts of "first" and "second" mentioned in this invention are only used to distinguish the corresponding contents and are not used to limit the order or interdependence.

[0012] It should be noted that the terms "a" and "a plurality of" used in this invention are illustrative rather than restrictive. Those skilled in the art should understand that, unless otherwise expressly indicated in the context, they should be understood as "one or more".

[0013] like Figure 1 , Figure 2 As shown, this invention discloses a variable linewidth and line spot system based on a cylindrical lens array, comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a cylindrical lens array 40 arranged sequentially along the optical axis from the object side to the image side. The first lens serves as a first lens group 10, which is fixed at the front end of the lens for light collection. The second, third, and fourth lenses combine to form a second lens group 20, and the fifth lens serves as a third lens group 30. The first lens group 10, the second lens group 20, and the third lens group 30 together constitute a zoom system. The positions of the first lens group 10, the third lens group 30, and the cylindrical lens array 40 are fixed, and the position of the third lens group 30 is fixed, with its relative distance to the first lens group 10 remaining constant, thereby fixing the total length of the entire lens. The second lens group 20, located between the first lens group 10 and the third lens group 30, moves towards or away from each other along the optical axis to achieve focal length variation. The first lens, second lens, third lens, fourth lens, and fifth lens are all made of transparent optical materials, such as optical glass or plastic. In this embodiment, the material used is fused silica optical glass.

[0014] The first lens group 10 and the second lens group 20 satisfy the following relationship: ; in, It is the focal length of the first lens group 10. It is the focal length of the second lens group 20; The first lens group 10 has negative refractive power; the second lens group 20 has positive refractive power; the second lens has positive refractive power; the third lens has negative refractive power; the fourth lens has positive refractive power; and the third lens group 30 has positive refractive power.

[0015] The cylindrical lens array 40 is composed of at least 7 sub-cylindrical lenses arranged in an array. The size, radius of curvature, thickness, and material of the sub-cylindrical lenses in the cylindrical lens array are all identical. The number of cylindrical lenses or the number of sub-beams in the cylindrical lens array can determine the uniformity of the line spot. Furthermore, the diameter of the light spot incident on the cylindrical lens array 40 is greater than the length of the arrangement period of at least 7 sub-cylindrical lenses, thereby ensuring the uniformity of the line spot. Due to the special shape of the cylindrical mirror, the light reflection is misaligned, and the image on the plane will be distorted. The distorted planar image is projected onto the cylindrical lens, and the cylindrical lens is distorted again. When the light is reflected by the cylindrical lens array 40, it will be focused at the focal point or dispersed from the virtual focal point. When a parallel beam is incident, the light will be divided by the cylindrical lens array 40 and superimposed to focus into a straight line. The distance between the second lens group and the first lens group 10 changes, the focusing position of the light spot changes, and the line width of the line spot at a fixed distance from the cylindrical lens array 40 changes.

[0016] This invention is particularly applicable to fields such as railway inspection or solar energy. In this invention, the positions of the first, third, and fourth lens groups are fixed. Changing the distance between the second lens group and the first lens group changes the focal length of the entire lens, thereby changing the focal position of the line spot and achieving the characteristic of adjustable linewidth of the spot at the same working distance. The entire zoom lens system has fewer lenses, a compact structure, an ultra-short size, and a uniform spot, giving the zoom lens excellent optical performance. Specifically, the incident light source enters from the first lens group, and the incident beam passes through the cylindrical lens array 40. The zoom system modulates the focal distance of the beam before the cylindrical lens array 40, changing the linewidth of the line spot to meet the linewidth requirements of different working environments. The incident beam can be a parallel beam from a laser or other light source. Each sub-cylindrical lens in the cylindrical lens array 40 divides the incident beam into multiple parallel line beams. The system functions similarly to a miniature prism, refracting the incident light beam into multiple beams in different directions. At the output of the cylindrical lens array 40, these segmented line beams are re-superimposed to form a uniform line spot. Changing the distance between the second lens group 20 and the first lens group 10 alters the focal length of the entire lens, thereby changing the linewidth of the uniform line spot formed by the cylindrical lens array. In other words, the zoom system expands the incident light beam, matching its size to the aperture of the cylindrical lens array. The zoom system modulates the focal length of the incident light beam. The cylindrical lens array achieves wavefront aperture segmentation to obtain a continuous and uniform line spot. The incident light forms a focused line spot after passing through the cylindrical lens array. The focal length of the incident light changes through the zoom system, and after passing through the cylindrical lens array, it forms focused spots at different focusing positions, thus modulating the linewidth of the line spot relative to the same focusing position.

[0017] For clarity, the present invention is described using the following data: The front end of the first lens group 10 is the incident light source, which is a fiber optic light source with a diameter of 200μm, a numerical aperture of 0.16, a wavelength of 808nm±10nm, and a power of 25W.

[0018] The lens parameters are shown in Table 1 below: Table 1

[0019] The structural parameters of the sub-cylinder lenses in the cylindrical lens array (unit: millimeters, mm) are shown in Table 2 below:

[0020] The object plane of the first lens is a plane, and the image plane is a concave arc. The object plane of the second lens is a convex arc surface, and the image plane is a concave arc surface; The object plane of the third lens is a concave arc surface, and the image plane is a concave arc surface; The object plane of the fourth lens is a concave arc surface, and the image plane is a convex arc surface; The object plane of the fifth lens is a plane, and the image plane is a convex arc. In Table 1, surfaces S1 and S2 are the two surfaces of the first lens; Surfaces S3 and S4 are the two surfaces of the second lens; Surfaces S5 and S6 are the two surfaces of the third lens; Surfaces S7 and S8 are the two surfaces of the fourth lens; Surfaces S9 and S10 are the two surfaces of the fifth lens; Surfaces S11 and S12 are the two surfaces of the cylindrical lens array; the aperture stop is set on surface 6; Furthermore, the radius of curvature of the first lens image plane 12 (i.e., surface S2) is 25.75 mm, and the thickness of the first lens is 3.5 mm; The second lens has an object plane 211 with a radius of curvature of 32.14 mm and an image plane 212 with a radius of curvature of 82.2 mm; the second lens has a thickness of 3.6 mm, and the distance between the image plane 12 of the first lens and the object plane 211 of the second lens is 11.8081 mm. The radius of curvature of the object plane 221 of the third lens is -77.86 mm, and the radius of curvature of the image plane 222 is 77.86 mm; the thickness of the third lens is 3.5 mm, and the distance between the image plane 212 of the second lens and the object plane 221 of the third lens is 2.0298 mm. The radius of curvature of the object plane 231 of the fourth lens is -82.20 mm, and the radius of curvature of the image plane 232 is -32.14 mm; the thickness of the fourth lens is 3.6 mm, and the distance between the image plane 222 of the third lens and the object plane 213 of the fourth lens is 6.5589 mm. The radius of curvature of the image plane 32 of the fifth lens is -38.8 mm, the thickness of the fifth lens is 7.5 mm, and the distance between the image plane 232 of the fourth lens and the object plane 31 of the fifth lens is 15.3296 mm. The radius of curvature of the cylindrical lens array object plane (i.e., surface S11) is 2.5 mm, the thickness of the cylindrical lens array is 2 mm, and the interval between the fifth lens image plane 32 and the cylindrical lens array 40 object plane (i.e., surface S11) is 20 mm. Among them, surface S2 has a variable spacing, surfaces S3, S4, S5, S6, and S7 have a constant spacing relative to S3, and surface S9 has a constant spacing relative to surface S1.

[0021] Figure 3 , 4 Figures 5 and 6 are schematic diagrams of the changes in the line spot structure at close, medium, and long distances, respectively. Specifically, Figure 3The distance between surfaces S2 shown is 10.4083 mm when focused at close range; Figure 4 The distance between surfaces S2 shown is 15.4083 mm when focused at a medium to long distance. Figure 5 The distance between surfaces S2 shown is 19.4083 mm when focused at a distance.

[0022] Figure 6 , 7 Figures 8 and 9 are schematic diagrams showing the changes in the line spot at the detector distance of 1200mm from the cylindrical lens array at close, medium and long distances, respectively. like Figure 9 The diagram showing the variation of the linewidth of the light spot is as follows: Figure 10 The diagram shown illustrates the focal length variation of the line spot. Figure 9 The horizontal axis ΔZ represents the distance between the second lens group and the first lens group, and the vertical axis RMS (Root Mean Square) radius is used to measure the size of the light spot. Figure 10 The vertical axis represents the focal length. Figure 10 This indicates the relationship between the moving distance (ΔZ) of the focusing lens group (second lens group) and the change in linewidth. Figure 10 It reflects the relationship between the moving distance of the focusing lens group (second lens group) and the change in focal length. Figure 9 and Figure 10 The effect of ΔZ on focal length and linewidth is intuitively shown, further demonstrating that the present invention has good optical performance according to the embodiments.

[0023] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0024] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A variable linewidth line spot system based on a cylindrical lens array, characterized in that: It comprises a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a cylindrical lens array arranged sequentially along the optical axis from the object side to the image side. The first lens serves as a first lens group, the second, third, and fourth lenses combine to form a second lens group, and the fifth lens serves as a third lens group. The first, second, and third lens groups together constitute a zoom system. The positions of the first, third, and cylindrical lens arrays are fixed, and the second lens group located between the first and third lens groups moves towards or away from each other along the optical axis to achieve focal length changes. The first lens group and the second lens group satisfy the following relationship: ； in, It is the focal length of the first lens group. It is the focal length of the second lens group; The first lens group has negative refractive power; the second lens group has positive refractive power, the second lens has positive refractive power, the third lens has negative refractive power, the fourth lens has positive refractive power; the third lens group has positive refractive power. The object plane of the first lens is a plane, and the image plane is a concave arc. The object plane of the second lens is a convex arc surface, and the image plane is a concave arc surface; The object plane of the third lens is a concave arc surface, and the image plane is a concave arc surface; The object plane of the fourth lens is a concave arc surface, and the image plane is a convex arc surface; The object plane of the fifth lens is a plane, and the image plane is a convex arc.

2. The variable linewidth line spot system based on a cylindrical lens array according to claim 1, characterized in that: The cylindrical lens array is composed of at least 7 sub-cylindrical lenses arranged in an array; and the diameter of the light spot incident on the cylindrical lens array is greater than the length of the arrangement period of the at least 7 sub-cylindrical lenses.

3. A variable linewidth line spot system based on a cylindrical lens array according to claim 1, characterized in that: The first lens, the second lens, the third lens, the fourth lens, and the fifth lens are all made of transparent optical materials.

4. A variable linewidth line spot system based on a cylindrical lens array according to claim 1, characterized in that: The first lens has a radius of curvature of 25.75 mm on its image plane and a thickness of 3.5 mm. The second lens has an object plane radius of curvature of 32.14 mm and an image plane radius of curvature of 82.2 mm; the second lens has a thickness of 3.6 mm; and the distance between the image plane of the first lens and the object plane of the second lens is 10~28 mm. The object plane of the third lens has a radius of curvature of -77.86 mm, and the image plane has a radius of curvature of 77.86 mm; the thickness of the third lens is 3.5 mm, and the distance between the image plane of the second lens and the object plane of the third lens is 2.0298 mm. The fourth lens has an object plane radius of curvature of -82.20 mm and an image plane radius of curvature of -32.14 mm; the fourth lens has a thickness of 3.6 mm; and the distance between the image plane of the third lens and the object plane of the fourth lens is 6.5589 mm. The radius of curvature of the image plane of the fifth lens is -38.8 mm, the thickness of the fifth lens is 7.5 mm, and the interval between the image plane of the fourth lens and the object plane of the fifth lens is 3.5~19.5 mm. The object plane of the cylindrical lens array has a radius of curvature of 2.5 mm, the thickness of the cylindrical lens array is 2 mm, and the distance between the image plane of the fifth lens and the object plane of the cylindrical lens array is 20 mm.

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