Telecentric flat-field lens and laser processing equipment

Abstract

The present invention discloses a telecentric flat-field lens and laser processing equipment. The telecentric flat-field lens includes an aperture, a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens arranged along the propagation direction of the incident light. The first lens, the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens are all meniscus lenses, and the meniscus direction of the first lens is the same as the propagation direction of the incident light. The meniscus direction of the second lens, the third lens, the fourth lens, the fifth lens and the sixth lens is opposite to the propagation direction of the incident light. The telecentric flat-field lens and laser processing equipment of the embodiment of the present invention can achieve a telecentricity within 6° by setting all 6 lenses to be meniscus lenses and reasonably setting the meniscus direction of each lens. When used in combination with a galvanometer lens in a laser processing equipment, it can achieve cutting of thin plates and can obtain good cutting effects.

Description

Technical Field

[0001] The present invention relates to the field of laser processing technology, and in particular to a telecentric flat-field lens and laser processing equipment. Background Art

[0002] As laser power becomes increasingly powerful, galvanometer lenses are no longer just used for marking and welding. More and more companies are beginning to use a galvanometer lens + flat-field lens method to cut thin plates.

[0003] However, the telecentricity of traditional field lenses is poor (the maximum field of view telecentricity is above 12°). After cutting, the edges and corners of the plate will have a certain slope, which requires subsequent processing to meet the application, increasing the processing cost. Summary of the Invention

[0004] The present invention provides a telecentric flat-field lens and laser processing equipment to achieve smaller telecentricity.

[0005] According to one aspect of the present invention, there is provided a telecentric flat-field lens comprising an aperture arranged along a propagation direction of incident light, a first lens, a second lens, a third lens, a fourth lens, a fifth lens, and a sixth lens;

[0006] The first lens is a meniscus lens, and the direction of the meniscus is the same as the propagation direction of the incident light;

[0007] The second lens is a meniscus lens, and the direction of the meniscus is opposite to the propagation direction of the incident light;

[0008] The third lens is a meniscus lens, and the direction of its meniscus is opposite to the propagation direction of the incident light;

[0009] The fourth lens is a meniscus lens, the meniscus direction of which is opposite to the propagation direction of the incident light;

[0010] The fifth lens is a meniscus lens, the meniscus direction of which is opposite to the propagation direction of the incident light;

[0011] The sixth lens is a meniscus lens, and the meniscus direction is opposite to the propagation direction of the incident light.

[0012] Optionally, a distance between the aperture and the first lens on the optical axis is d1, where 33 mm ≤ d1 ≤ 37 mm.

[0013] Optionally, the radius of curvature of the object side surface of the first lens is R11, the radius of curvature of the image side surface of the first lens is R12, and the center thickness of the first lens on its optical axis is d2, wherein 608mm≤R11≤673mm, 153mm≤R12≤170mm, and 12mm≤d2≤14mm.

[0014] Optionally, the radius of curvature of the object side surface of the second lens is R21, the radius of curvature of the image side surface of the second lens is R22, and the center thickness of the second lens on its optical axis is d4, where -77mm≤R21≤-66mm, -107mm≤R22≤-96mm, and 11mm≤d4≤13mm.

[0015] Optionally, the radius of curvature of the object side surface of the third lens is R31, the radius of curvature of the image side surface of the third lens is R32, and the center thickness of the third lens on its optical axis is d6, wherein -239mm≤R31≤-215mm, -155mm≤R32≤-139mm, and 28mm≤d6≤31mm.

[0016] Optionally, the radius of curvature of the object side surface of the fourth lens is R41, the radius of curvature of the image side surface of the fourth lens is R42, and the center thickness of the fourth lens on its optical axis is d8, wherein -315mm≤R41≤-284mm, -192mm≤R42≤-173mm, and 28mm≤d8≤32mm.

[0017] Optionally, the radius of curvature of the object side surface of the fifth lens is R51, the radius of curvature of the image side surface of the fifth lens is R52, and the center thickness of the fifth lens on its optical axis is d10, where -473mm≤R51≤-427mm, -247mm≤R52≤-222mm, and 29mm≤d10≤31mm.

[0018] Optionally, the radius of curvature of the object side surface of the sixth lens is R61, the radius of curvature of the image side surface of the sixth lens is R62, and the center thickness of the sixth lens on its optical axis is d12, where -375mm≤R61≤-338mm, -231mm≤R62≤-208mm, and 29mm≤d12≤31mm.

[0019] Optionally, the distance between the first lens and the second lens on the optical axis is d3, the distance between the second lens and the third lens on the optical axis is d5, the distance between the third lens and the fourth lens on the optical axis is d7, the distance between the fourth lens and the fifth lens on the optical axis is d9, the distance between the fifth lens and the sixth lens on the optical axis is d11, and the distance between the sixth lens and the focused image plane on the optical axis is d13, wherein 78mm≤d3≤87mm, 13mm≤d5≤16mm, 1mm≤d7≤3mm, 1mm≤d9≤3mm, 1mm≤d11≤3mm, and 698mm≤d13≤772mm.

[0020] According to another aspect of the present invention, there is provided a laser processing device comprising any one of the telecentric flat-field lenses described in the first aspect.

[0021] The telecentric flat-field lens and laser processing equipment of the present invention utilize six lenses, all of which are meniscus lenses, with the meniscus orientation of each lens properly adjusted. This achieves a maximum field of view telecentricity of less than 6°, resulting in a low telecentricity. When used with a galvanometer lens in laser processing equipment, the telecentric flat-field lens can achieve excellent cutting results on thin sheets, eliminating the need for subsequent processing and reducing processing costs.

[0022] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present invention, nor is it intended to limit the scope of the present invention. Other features of the present invention will become readily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 A schematic structural diagram of a telecentric flat-field lens provided by an embodiment of the present invention;

[0025] Figure 2 A schematic diagram of the optical path structure of a telecentric flat-field lens provided in an embodiment of the present invention;

[0026] Figure 3 A spot diagram of a telecentric flat-field lens provided by an embodiment of the present invention;

[0027] Figure 4 This is a field curvature distortion diagram of a telecentric flat-field lens provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the solutions of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts should fall within the scope of protection of the present invention.

[0029] It should be noted that the terms "first", "second", etc. in the description and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0030] Figure 1 A schematic structural diagram of a telecentric flat-field lens provided by an embodiment of the present invention is shown in FIG. Figure 1 As shown, the telecentric flat-field lens provided by the embodiment of the present invention includes an aperture L0, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5 and a sixth lens L6 arranged along the propagation direction of the incident light. The first lens L1 is a meniscus lens, and the direction of its meniscus is the same as the propagation direction of the incident light. The second lens L2 is a meniscus lens, and the direction of its meniscus is opposite to the propagation direction of the incident light. The third lens L3 is a meniscus lens, and the direction of its meniscus is opposite to the propagation direction of the incident light. The fourth lens L4 is a meniscus lens, and the direction of its meniscus is opposite to the propagation direction of the incident light. The fifth lens L5 is a meniscus lens, and the direction of its meniscus is opposite to the propagation direction of the incident light. The sixth lens L6 is a meniscus lens, and the direction of its meniscus is opposite to the propagation direction of the incident light.

[0031] Specifically, the telecentric flat-field lens provided in this embodiment comprises six lenses. By configuring all six lenses as meniscus lenses and properly aligning the meniscus orientations of each lens, a maximum field of view telecentricity of less than 6° can be achieved, resulting in a low telecentricity. When used with a galvanometer lens in laser processing equipment, it can achieve excellent cutting results on thin sheets, eliminating the need for subsequent processing and thus reducing processing costs.

[0032] Among them, the direction of the meniscus is the same as the propagation direction of the incident light, which means that the centers of the object side surface (spherical surface) and the image side surface (spherical surface) of the lens are both located on the image side of the lens; the direction of the meniscus is opposite to the propagation direction of the incident light, which means that the centers of the object side surface (spherical surface) and the image side surface (spherical surface) of the lens are both located on the object side of the lens, the object side surface refers to the surface of the lens away from the focused image plane, and the image side surface refers to the surface of the lens facing the focused image plane.

[0033] At the same time, the telecentric flat-field lens provided in the embodiment of the present invention can have a focal length of 460mm. When used with a galvanometer lens in laser processing equipment, it can achieve a cutting range of 230mm*230mm, and the incident wavelength can be 1064nm, but is not limited to this.

[0034] As a feasible implementation method, Figure 1 As shown, the distance between the aperture L0 and the first lens L1 on the optical axis is d1, where 33 mm ≤ d1 ≤ 37 mm.

[0035] Specifically, the aperture L0 can adjust the propagation direction of the light beam. In this embodiment, by reasonably setting the distance d1 between the aperture L0 and the first lens L1 on the optical axis, it is helpful to further reduce the maximum field of view telecentricity.

[0036] In addition, the aperture size of the diaphragm L0 can be set to 24mm so that the entrance pupil diameter is 24mm, so that it can be used with various types of galvanometer lenses to meet the needs of laser processing equipment.

[0037] As a feasible implementation method, Figure 1 As shown, the radius of curvature of the object-side surface S1 of the first lens L1 is R11, the radius of curvature of the image-side surface S2 of the first lens L1 is R12, and the center thickness of the first lens L1 on the optical axis is d2, where 608 mm ≤ R11 ≤ 673 mm, 153 mm ≤ R12 ≤ 170 mm, and 12 mm ≤ d2 ≤ 14 mm.

[0038] Specifically, by properly setting the curvature radii of the object-side surface S1 and the image-side surface S2 of the first lens element L1, as well as the center thickness d2 of the first lens element L1 on its optical axis, it helps to further reduce the maximum field of view telecentricity. At the same time, the thickness of the first lens element L1 can be made uniform, thereby facilitating processing and assembly.

[0039] As a feasible implementation method, Figure 1 As shown, the radius of curvature of the object-side surface S3 of the second lens L2 is R21, the radius of curvature of the image-side surface S4 of the second lens L2 is R22, and the center thickness of the second lens L2 on the optical axis is d4, where -77 mm ≤ R21 ≤ -66 mm, -107 mm ≤ R22 ≤ -96 mm, and 11 mm ≤ d4 ≤ 13 mm.

[0040] Specifically, by properly setting the curvature radii of the object-side surface S3 and the image-side surface S4 of the second lens element L2, as well as the center thickness d4 of the second lens element L2 on its optical axis, it helps to further reduce the maximum field of view telecentricity. At the same time, the thickness of the second lens element L2 can be made uniform, thereby facilitating processing and assembling.

[0041] As a feasible implementation method, Figure 1 As shown, the radius of curvature of the object-side surface S5 of the third lens L3 is R31, the radius of curvature of the image-side surface S6 of the third lens L3 is R32, and the center thickness of the third lens L3 on the optical axis is d6, where -239 mm ≤ R31 ≤ -215 mm, -155 mm ≤ R32 ≤ -139 mm, and 28 mm ≤ d6 ≤ 31 mm.

[0042] Specifically, by properly setting the curvature radii of the object-side surface S5 and the image-side surface S6 of the third lens element L3, as well as the center thickness d6 of the third lens element L3 on its optical axis, it helps to further reduce the maximum field of view telecentricity. At the same time, the thickness of the third lens element L3 can be made uniform, thereby facilitating processing and assembling.

[0043] As a feasible implementation method, Figure 1 As shown, the radius of curvature of the object-side surface S7 of the fourth lens L4 is R41, the radius of curvature of the image-side surface S8 of the fourth lens L4 is R42, and the center thickness of the fourth lens L4 on the optical axis is d8, where -315 mm ≤ R41 ≤ -284 mm, -192 mm ≤ R42 ≤ -173 mm, and 28 mm ≤ d8 ≤ 32 mm.

[0044] Specifically, by properly setting the curvature radii of the object-side surface S7 and the image-side surface S8 of the fourth lens element L4, as well as the center thickness d8 of the fourth lens element L4 on its optical axis, it helps to further reduce the maximum field of view telecentricity. At the same time, the thickness of the fourth lens element L4 can be made uniform, thereby facilitating processing and assembling.

[0045] As a feasible implementation method, Figure 1 As shown, the radius of curvature of the object-side surface S9 of the fifth lens element L5 is R51, the radius of curvature of the image-side surface S10 of the fifth lens element L5 is R52, and the center thickness of the fifth lens element L5 on the optical axis is d10, where -473 mm ≤ R51 ≤ -427 mm, -247 mm ≤ R52 ≤ -222 mm, and 29 mm ≤ d10 ≤ 31 mm.

[0046] Specifically, by properly setting the curvature radii of the object-side surface S9 and the image-side surface S10 of the fifth lens element L5, as well as the center thickness d10 of the fifth lens element L5 on its optical axis, it helps to further reduce the maximum field of view telecentricity. At the same time, the thickness of the fifth lens element L5 can be made uniform, thereby facilitating processing and assembly.

[0047] As a feasible implementation method, Figure 1As shown, the radius of curvature of the object-side surface S11 of the sixth lens L6 is R61, the radius of curvature of the image-side surface S12 of the sixth lens L6 is R62, and the center thickness of the sixth lens L6 along the optical axis is d12, where -375 mm ≤ R61 ≤ -338 mm, -231 mm ≤ R62 ≤ -208 mm, and 29 mm ≤ d12 ≤ 31 mm.

[0048] Specifically, by properly setting the curvature radii of the object-side surface S11 and the image-side surface S12 of the sixth lens element L6, as well as the center thickness d12 of the sixth lens element L6 on its optical axis, it helps to further reduce the maximum field of view telecentricity. At the same time, the thickness of the sixth lens element L6 can be made uniform, thereby facilitating processing and assembling.

[0049] As a feasible implementation method, Figure 1 As shown, the distance on the optical axis between the first lens L1 and the second lens L2 is d3, the distance on the optical axis between the second lens L2 and the third lens L3 is d5, the distance on the optical axis between the third lens L3 and the fourth lens L4 is d7, the distance on the optical axis between the fourth lens L4 and the fifth lens L5 is d9, the distance on the optical axis between the fifth lens L5 and the sixth lens L6 is d11, and the distance on the optical axis between the sixth lens L6 and the focused image plane is d13. Here, 78 mm ≤ d3 ≤ 87 mm, 13 mm ≤ d5 ≤ 16 mm, 1 mm ≤ d7 ≤ 3 mm, 1 mm ≤ d9 ≤ 3 mm, 1 mm ≤ d11 ≤ 3 mm, and 698 mm ≤ d13 ≤ 772 mm.

[0050] Among them, by reasonably setting the spacing between adjacent lenses on the optical axis, it helps to further reduce the maximum field of view telecentricity. At the same time, it can also make the thickness of the six lenses uniform, making them easy to process and convenient to assemble.

[0051] For example, the specific optical and physical parameters of each lens in the telecentric flat-field lens provided by an embodiment of the present invention are described in detail below using a feasible implementation manner.

[0052] Specifically, such as Figure 1As shown, the telecentric flat-field lens provided by the embodiment of the present invention includes an aperture L0, a first lens L1, a second lens L2, a third lens L3, a fourth lens L4, a fifth lens L5 and a sixth lens L6 arranged along the propagation direction of the incident light. The first lens L1 is a meniscus lens, and the direction of its meniscus is the same as the propagation direction of the incident light. The second lens L2 is a meniscus lens, and the direction of its meniscus is opposite to the propagation direction of the incident light. The third lens L3 is a meniscus lens, and the direction of its meniscus is opposite to the propagation direction of the incident light. The fourth lens L4 is a meniscus lens, and the direction of its meniscus is opposite to the propagation direction of the incident light. The fifth lens L5 is a meniscus lens, and the direction of its meniscus is opposite to the propagation direction of the incident light. The sixth lens L6 is a meniscus lens, and the direction of its meniscus is opposite to the propagation direction of the incident light.

[0053] The aperture of the stop L0 is 24 mm, and the distance d1 between the stop L0 and the first lens L1 on the optical axis is 35 mm.

[0054] The curvature radius R11 of the object-side surface of the first lens L1 is 640.017 mm, the curvature radius R12 of the image-side surface S2 of the first lens L1 is 161.355 mm, and the center thickness d2 of the first lens L1 on the optical axis is 12.84 mm.

[0055] The curvature radius R21 of the object-side surface S3 of the second lens L2 is -69.771 mm, the curvature radius R22 of the image-side surface S4 of the second lens L2 is -101.128 mm, and the center thickness d4 of the second lens L2 on the optical axis is 12.04 mm.

[0056] The curvature radius R31 of the object-side surface S5 of the third lens L3 is -226.758 mm, the curvature radius R32 of the image-side surface S6 of the third lens L3 is -146.667 mm, and the center thickness d6 of the third lens L3 on the optical axis is 29.48 mm.

[0057] The curvature radius R41 of the object-side surface S7 of the fourth lens L4 is -299.878 mm, the curvature radius R42 of the image-side surface S8 of the fourth lens L4 is -182.091 mm, and the center thickness d8 of the fourth lens L4 on the optical axis is 29.99 mm.

[0058] The curvature radius R51 of the object-side surface S9 of the fifth lens L5 is -449.730 mm, the curvature radius R5 of the image-side surface S10 of the fifth lens L5 is -234.685 mm, and the center thickness d10 of the fifth lens L5 on the optical axis is 30.00 mm.

[0059] The curvature radius R61 of the object-side surface S11 of the sixth lens L6 is -356.212 mm, the curvature radius R62 of the image-side surface S12 of the sixth lens L6 is -219.551 mm, and the center thickness d12 of the sixth lens L6 on the optical axis is 30.00 mm.

[0060] The distance d3 between the first lens L1 and the second lens L2 on the optical axis is 82.37 mm, the distance d5 between the second lens L2 and the third lens L3 on the optical axis is 14.29 mm, the distance d7 between the third lens L3 and the fourth lens L4 on the optical axis is 2.00 mm, the distance d9 between the fourth lens L4 and the fifth lens L5 on the optical axis is 2.00 mm, the distance d11 between the fifth lens L5 and the sixth lens L6 on the optical axis is 2.00 mm, and the distance d13 between the sixth lens L6 and the focused image plane on the optical axis is 734.81 mm.

[0061] The combination of the lenses in this embodiment creates a telecentric flat-field lens with a focal length of 460mm. When the incident light is 1064nm infrared light, the entrance pupil diameter (maximum spot diameter) is 24mm, resulting in a scanning range of 230mm*230mm and a telecentricity of ≤6°, demonstrating a low telecentricity. When used in conjunction with a galvanometer lens in laser processing equipment, this telecentric flat-field lens can achieve excellent cutting results on thin sheets, eliminating the need for subsequent processing and thus reducing processing costs. Furthermore, the uniform thickness of each lens makes it easy to process and assemble.

[0062] It should be noted that the correction range of the curvature radius, interval and material parameters of the above-mentioned lens surfaces is ±5%.

[0063] Further, Figure 2 A schematic diagram of the optical path structure of a telecentric flat-field lens provided in an embodiment of the present invention is shown in FIG. Figure 2 As shown in the figure, the maximum field of view angle of the telecentric flat-field lens can reach 21°, which can have a large scanning range. At the maximum field of view angle, the telecentricity of the light is less than 6°. When the telecentric flat-field lens is used in conjunction with a galvanometer lens in laser processing equipment, it can achieve cutting of thin plates and obtain good cutting effects without the need for subsequent processing, thereby reducing processing costs.

[0064] Figure 3 The present invention provides a spot diagram of a telecentric flat-field lens. The spot diagram is one of the most commonly used evaluation methods in modern optical design. The spot diagram refers to the pattern of diffuse spots scattered over a certain range formed by the intersection of many light rays emitted by a point light source with the image plane after passing through the optical system due to aberrations. The shape and size of the diffuse spots reflect the aberration of the lens after imaging. Figure 3As shown in the figure, the root mean square radius values ​​(RMS radius) of the light at each field position of the telecentric flat-field lens are 4.031μm, 13.261μm, 24.582μm and 42.039μm respectively, indicating that its maximum RMS (root mean square) diffuse spot radius is 42.039, which means that the beam quality of the laser is less affected after being focused by the telecentric flat-field lens, and it has low chromatic aberration and aberration, and can be applied to various laser processing occasions.

[0065] Figure 4 This is a field curvature distortion diagram of a telecentric flat field lens provided by an embodiment of the present invention, such as Figure 4 As shown in the left coordinate system, the horizontal coordinate represents the magnitude of the field curvature, in mm; the vertical coordinate represents the normalized image height, without units; T represents the meridian, S represents the arc loss; the field curvature reflects the degree of curvature of the laser processing focal plane under different fields of view, which is represented by Figure 4 It can be seen that the telecentric flat-field lens provided in the embodiment of the present invention has a maximum field curvature of less than 1.94 mm at a field of view of 1.0, and the field curvature is effectively controlled. That is, during imaging, the difference in image quality between the center and the periphery is small, thereby achieving good laser processing effects.

[0066] Continue to refer Figure 4 In the coordinate system on the right, the horizontal coordinate represents the size of the distortion, and the unit is %; the vertical coordinate represents the normalized image height, and there is no unit. Among them, if the telecentric flat field lens is to achieve a good laser processing effect, it is necessary to control the F-θ distortion, which is given by Figure 4 It can be seen that the maximum F-θ distortion of the telecentric flat-field lens provided in this embodiment is less than 0.4%, the distortion is well corrected, the imaging distortion is small, and a good laser processing effect can be achieved.

[0067] Based on the same inventive concept, an embodiment of the present invention further provides a laser processing device, which includes the telecentric flat-field lens described in any embodiment of the present invention. Therefore, the laser processing device provided by the embodiment of the present invention has the technical effects of the technical solutions in any of the above embodiments, and the structures that are the same or corresponding to the above embodiments and the explanation of terms are no longer repeated here.

[0068] Specifically, when used with the galvanometer lens in laser processing equipment, the telecentric flat-field lens achieves an entrance pupil diameter (maximum spot diameter) of 24mm when incident light is 1064nm infrared light. This allows for a maximum marking / welding / cutting range of 230mm*230mm, with a telecentricity of ≤6°, demonstrating a low degree of telecentricity. When used with the galvanometer lens in laser processing equipment, this telecentric flat-field lens can achieve excellent cutting results on thin sheets, eliminating the need for subsequent processing and thus reducing processing costs.

[0069] The above specific embodiments do not limit the scope of protection of the present invention. Those skilled in the art will appreciate that various modifications, combinations, sub-combinations, and substitutions may be made based on design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention are intended to be included within the scope of protection of the present invention.

Claims

1. A telecentric flat-field lens, characterized in that: It consists of an aperture arranged along the propagation direction of the incident light, a first lens, a second lens, a third lens, a fourth lens, a fifth lens and a sixth lens; The first lens is a meniscus lens, and the direction of the meniscus is the same as the propagation direction of the incident light; The second lens is a meniscus lens, and the direction of the meniscus is opposite to the propagation direction of the incident light; The third lens is a meniscus lens, and the direction of its meniscus is opposite to the propagation direction of the incident light; The fourth lens is a meniscus lens, the meniscus direction of which is opposite to the propagation direction of the incident light; The fifth lens is a meniscus lens, the meniscus direction of which is opposite to the propagation direction of the incident light; The sixth lens is a meniscus lens, and the direction of its meniscus is opposite to the propagation direction of the incident light; A distance between the first lens and the second lens on the optical axis is d3, a distance between the second lens and the third lens on the optical axis is d5, a distance between the third lens and the fourth lens on the optical axis is d7, a distance between the fourth lens and the fifth lens on the optical axis is d9, a distance between the fifth lens and the sixth lens on the optical axis is d11, and a distance between the sixth lens and the focused image plane on the optical axis is d13, wherein 78 mm ≤ d3 ≤ 87 mm, 13 mm ≤ d5 ≤ 16 mm, 1 mm ≤ d7 ≤ 3 mm, 1 mm ≤ d9 ≤ 3 mm, 1 mm ≤ d11 ≤ 3 mm, and 698 mm ≤ d13 ≤ 772 mm.

2. The telecentric flat-field lens according to claim 1, wherein: The distance between the aperture and the first lens on the optical axis is d1, where 33 mm ≤ d1 ≤ 37 mm.

3. The telecentric flat-field lens according to claim 1, wherein: The radius of curvature of the object-side surface of the first lens is R11, the radius of curvature of the image-side surface of the first lens is R12, and the center thickness of the first lens on its optical axis is d2, wherein 608 mm ≤ R11 ≤ 673 mm, 153 mm ≤ R12 ≤ 170 mm, and 12 mm ≤ d2 ≤ 14 mm.

4. The telecentric flat-field lens according to claim 1, wherein: The radius of curvature of the object-side surface of the second lens is R21, the radius of curvature of the image-side surface of the second lens is R22, and the center thickness of the second lens on its optical axis is d4, where -77 mm ≤ R21 ≤ -66 mm, -107 mm ≤ R22 ≤ -96 mm, and 11 mm ≤ d4 ≤ 13 mm.

5. The telecentric flat-field lens according to claim 1, wherein: The radius of curvature of the object side surface of the third lens is R31, the radius of curvature of the image side surface of the third lens is R32, and the center thickness of the third lens on its optical axis is d6, wherein -239mm≤R31≤-215mm, -155mm≤R32≤-139mm, and 28mm≤d6≤31mm.

6. The telecentric flat-field lens according to claim 1, wherein: The curvature radius of the object side surface of the fourth lens is R41, the curvature radius of the image side surface of the fourth lens is R42, and the center thickness of the fourth lens on its optical axis is d8, wherein -315mm≤R41≤-284mm, -192mm≤R42≤-173mm, and 28mm≤d8≤32mm.

7. The telecentric flat-field lens according to claim 1, wherein: The object-side surface of the fifth lens has a curvature radius of R51, the image-side surface of the fifth lens has a curvature radius of R52, and the center thickness of the fifth lens on its optical axis is d10, wherein -473 mm ≤ R51 ≤ -427 mm, -247 mm ≤ R52 ≤ -222 mm, and 29 mm ≤ d10 ≤ 31 mm.

8. The telecentric flat-field lens according to claim 1, wherein: The object-side surface of the sixth lens has a curvature radius of R61, the image-side surface of the sixth lens has a curvature radius of R62, and the center thickness of the sixth lens on its optical axis is d12, wherein -375 mm ≤ R61 ≤ -338 mm, -231 mm ≤ R62 ≤ -208 mm, and 29 mm ≤ d12 ≤ 31 mm.

9. A laser processing device, characterized in that: The invention comprises the telecentric flat field lens according to any one of claims 1 to 8.

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