CO2 telecentric scanning field lens

Abstract

The utility model belongs to the technical field of optics, and discloses a CO2 telecentric scanning field lens, which is applied to CO2 laser and comprises a first lens, a second lens, a third lens and a protective lens which are sequentially arranged along the incident direction of a light beam, the first lens is a negative-focal-power lens of a meniscus structure, the second lens is a positive-focal-power lens of a meniscus structure, the third lens is a positive-focal-power lens of a biconvex structure, the protective lens is of a flat plate structure, the concave surfaces of the first lens and the second lens face the laser incident direction, and the concave surfaces of the first lens and the second lens face the concave surface of the third lens. The lenses form negative-positive-positive focal power distribution, compact distribution and aberration correction are achieved, it is ensured that a laser beam keeps vertical incidence in the whole machining field of view, the problem of focus offset caused by light beam inclination of a traditional field lens is solved, the focusing difference between paraxial light beams and marginal light beams is eliminated, the phenomenon that the edge of a drilled hole has taper is avoided, and the machining precision of the drilled hole is improved. The rejection rate is effectively reduced and the product performance and reliability are improved.

Description

Technical Field

[0001] This utility model relates to the field of optical technology, and in particular to a CO2 telecentric scanning field lens. Background Technology

[0002] In modern industrial manufacturing, laser drilling technology is widely used due to its high precision and non-contact processing characteristics. However, traditional laser drilling usually uses ordinary optical lenses, but ordinary optical lenses cannot precisely control the beam, causing the focus to frequently shift during the drilling process. This not only causes fluctuations in the hole diameter, making it difficult to stabilize the processed hole diameter within the specified range and seriously affecting the dimensional accuracy of the product, but also causes the incident angle of the edge beam to tilt, resulting in taper problems in the hole wall, which damages the perpendicularity of the hole wall and greatly reduces the product quality. Utility Model Content

[0003] The main purpose of this invention is to provide a CO2 telecentric scanning field lens, which aims to solve the technical problems of existing laser drilling processes using ordinary optical lenses, which easily cause the drilling focus to shift, resulting in hole diameter fluctuations and the tilting of the incident angle of the edge beam causing hole wall taper.

[0004] In order to achieve the above-mentioned utility model objectives, this utility model proposes a CO2 telecentric scanning field lens for use with CO2 lasers, comprising a first lens, a second lens, a third lens, and a protective lens arranged sequentially along the incident direction of the beam;

[0005] The first lens is a negative power lens with a meniscus structure, the second lens is a positive power lens with a meniscus structure, the third lens is a positive power lens with a biconvex structure, and the protective lens is a flat plate structure. The concave surfaces of the first lens and the second lens face the laser incident direction, respectively.

[0006] Furthermore, the CO2 telecentric scanning field mirror also includes an entrance pupil plane and an image plane;

[0007] The entrance pupil surface is located on the side of the first lens away from the second lens, and the image surface is located on the side of the protective lens away from the third lens. The first interval between the entrance pupil surface and the first lens is 35 mm, the second interval between the first lens and the second lens is 1.2 mm, the third interval between the second lens and the third lens is 29 mm, the fourth interval between the third lens and the protective lens is 3 mm, and the fifth interval between the image surface and the protective lens is 123 mm.

[0008] Furthermore, the radii of curvature on the front and rear sides of the first lens are -43mm and -205mm, respectively, and the thickness of the first center of the first lens is 5mm.

[0009] Furthermore, the radii of curvature on the front and rear sides of the second lens are -164mm and -52mm, respectively, and the thickness of the second center of the second lens is 10.5mm.

[0010] Furthermore, the radii of curvature on the front and rear sides of the third lens are 317mm and -317mm, respectively, and the thickness of the third center of the third lens is 10mm.

[0011] Furthermore, the fourth center thickness of the protective mirror is 3mm.

[0012] Furthermore, the total focal length of the CO2 telecentric scanning field lens is f, and the focal lengths of the first lens, the second lens, and the third lens are f1, f2, and f3, respectively, wherein the total focal length f of the CO2 telecentric scanning field lens satisfies the following relationship: -0.6 <f1 / f<-0.25,0.3<f2 / f<0.65,0.9<f3 / f<1.3。

[0013] Furthermore, the first lens, the second lens, the third lens, and the protective lens are all made of zinc selenide lenses.

[0014] Furthermore, the refractive index of the first lens, the second lens, the third lens, and the protective mirror is all 2.4.

[0015] Furthermore, the entire CO2 telecentric scanning field lens has a focal length of 100mm, a wavelength of 9.6μm, a telecentricity of 2.4°, an optical scanning angle of ±21°, an incident beam diameter of 20mm, a scanning range of 50mm*50mm, and a focused spot size of 84-86μm.

[0016] Beneficial effects:

[0017] This invention relates to a CO2 telecentric scanning field lens for use with CO2 lasers. It comprises a first lens, a second lens, a third lens, and a protective mirror arranged sequentially along the beam incident direction. The first lens is a meniscus negative power lens, the second lens is a meniscus positive power lens, the third lens is a biconvex positive power lens, and the protective mirror is a flat plate structure. The concave surfaces of the first and second lenses face the laser incident direction. Therefore, the multiple lenses of the CO2 telecentric scanning field lens form a "negative-positive-positive" power distribution, achieving compact distribution and aberration correction. This ensures the laser beam remains perpendicularly incident throughout the entire processing field of view, eliminating the focus shift problem caused by beam tilt in traditional field lenses. By eliminating the focusing difference between paraxial and edge beams, it avoids taper at the drilling edge, effectively reducing the scrap rate and improving product performance and reliability. Attached Figure Description

[0018] Figure 1 This is an optical path diagram of a CO2 telecentric scanning field mirror according to an embodiment of the present invention;

[0019] Figure 2 This is a field curvature and F-theta distortion image of a CO2 telecentric scanning field lens according to an embodiment of the present invention;

[0020] Figure 3 This is a dot plot of a CO2 telecentric scanning field mirror according to an embodiment of the present invention;

[0021] Figure 4 This is the optical transfer function (MTF) plot of a CO2 telecentric scanning field lens according to an embodiment of the present invention.

[0022] in:

[0023] G1, First lens; G2, Second lens; G3, Third lens; SG, Protective lens;

[0024] d0, first interval; d2, second interval; d4, third interval; d6, fourth interval; d8, fifth interval;

[0025] d1, first center thickness; d3, second center thickness; d5, third center thickness; d7, fourth center thickness.

[0026] The realization of the purpose, functional features and advantages of this utility model will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0027] It should be understood that the specific embodiments described herein are merely illustrative of the present invention and are not intended to limit the present invention.

[0028] In the description of this utility model, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience of describing this utility model and simplifying the description. They do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this utility model. Furthermore, 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. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of the stated features. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly and specifically defined.

[0029] In the description of this utility model, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "joining" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, a direct connection, or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0030] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can include direct contact between the first and second features, or contact between the first and second features through another feature between them. Furthermore, "above," "over," and "on top" of the second feature includes the first feature directly above or diagonally above the second feature, or simply indicates that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature includes the first feature directly below or diagonally below the second feature, or simply indicates that the first feature is at a lower horizontal level than the second feature.

[0031] Reference Figures 1-4 This embodiment provides a CO2 telecentric scanning field lens for use with CO2 lasers, including a first lens G1, a second lens G2, a third lens G3 and a protective lens SG arranged sequentially along the incident direction of the beam;

[0032] The first lens G1 is a negative power lens with a meniscus structure, the second lens G2 is a positive power lens with a meniscus structure, the third lens G3 is a positive power lens with a biconvex structure, and the protective lens SG is a flat plate structure. The concave surfaces of the first lens G1 and the second lens G2 face the laser incident direction, respectively.

[0033] In the above embodiments, a CO2 telecentric scanning field lens is applied in CO2 laser processing. Specifically, the CO2 telecentric field lens is an optical element combining telecentric optical path design and F-Theta nonlinear correction function. It is designed specifically for high-precision processing and scanning systems using CO2 lasers (infrared lasers with a wavelength of 9.6 μm generated by CO2 gas). Combined with a galvanometer system, it enables high-precision QR code and serial number marking on the surfaces of materials such as metals, plastics, and ceramics. It can also be applied to micro-hole drilling in PCB boards and semiconductor packaging. The CO2 telecentric scanning field lens includes a first lens G1, a second lens G2, a third lens G3, and a protective mirror SG. The first lens G1 is a meniscus negative power lens with an outwardly curved shape, which can diverge the light passing through it, thereby achieving... The first lens G1 reduces the diameter of the incident beam; the second lens G2 also adopts a meniscus structure, but it is a positive focal power lens. Unlike the first lens G1, its function is to converge the light and form a focusing effect; the third lens G3 adopts a biconvex structure, which is a design with both ends convex outward, which can further enhance the light converging ability. The protective lens SG is a transparent element with a flat structure, mainly used to protect other lenses from the influence of the external environment. The first lens G1, the second lens G2, the third lens G3 and the protective lens SG are arranged sequentially along the incident direction of the laser beam, that is, starting from the laser source, it first passes through the first lens G1, then the second lens G2, then the third lens G3, and finally reaches the protective lens SG. The concave surfaces of the first lens G1 and the second lens G2 face the incident direction of the laser beam. Therefore, by using multiple lenses of the CO2 telecentric scanning field lens to form a "negative-positive-positive" optical power distribution, a compact distribution and aberration correction are achieved, ensuring that the laser beam remains perpendicular to the entire processing field of view. This eliminates the focus shift problem caused by beam tilt in traditional field lenses. By eliminating the focusing difference between paraxial and edge beams, taper at the drilling edge is avoided, effectively reducing the scrap rate and improving product performance and reliability.

[0034] Reference Figures 1-4 In one embodiment, the CO2 telecentric scanning field mirror further includes an entrance pupil plane and an image plane;

[0035] The entrance pupil surface is located on the side of the first lens G1 away from the second lens G2, and the image plane is located on the side of the protective lens SG away from the third lens G3. The first interval d0 between the entrance pupil surface and the first lens G1 is 35 mm, the second interval d2 between the first lens G1 and the second lens G2 is 1.2 mm, the third interval d4 between the second lens G2 and the third lens G3 is 29 mm, the fourth interval d6 between the third lens G3 and the protective lens SG is 3 mm, and the fifth interval d8 between the image plane and the protective lens SG is 123 mm.

[0036] In the above embodiment, the CO2 telecentric scanning field mirror further includes an entrance pupil surface and an image surface. The entrance pupil surface refers to the first effective optical surface in which light enters the system, located on the side of the first lens G1 away from the second lens G2. The first interval d0 between the entrance pupil surface and the first lens G1 is 35mm. The first interval d0 ensures that the laser beam has sufficient space for initial adjustment before entering the first lens G1. The interval between the first lens G1 and the second lens G2 is 1.2mm. This small distance precisely controls the propagation path of the light and ensures effective focusing of the beam. The interval between the second lens G2 and the third lens G3 is set to 29mm, which helps to optimize the transmission efficiency and quality of the light. The protective mirror SG is located after the third lens G3, and the interval between the third lens G3 and the protective mirror SG is 3mm. Finally, the image surface is located on the side of the protective mirror SG away from the third lens G3, and the interval between the protective mirror SG and the protective mirror SG is 123mm. This is the final imaging position and also the target area for laser processing. Furthermore, the radii of curvature on the front and rear sides of the first lens G1 are -43mm and -205mm respectively, meaning its concave surface faces the incident beam direction, and its convex surface faces the second lens G2. The first center thickness d1 of the first lens G1 is 5mm. The radii of curvature on the front and rear sides of the second lens G2 are -164mm and -52mm respectively; similarly, its concave surface also faces the incident beam direction. The second center thickness d3 of the second lens G2 is 10.5mm. The radii of curvature on the front and rear sides of the third lens G3 are 317mm and -317mm respectively, and the third center thickness d5 of the third lens G3 is 10mm. The fourth center thickness d7 of the protective lens SG is 3mm. By precisely setting the intervals between each component, fine control of the light path is achieved, ensuring high resolution and clear imaging effects, and guaranteeing that the laser beam remains perpendicularly incident throughout the entire processing field of view.

[0037] Reference Figures 1-4 In one embodiment, the total focal length of the CO2 telecentric scanning field lens is f, and the focal lengths of the first lens G1, the second lens G2, and the third lens G3 are f1, f2, and f3, respectively, wherein the total focal length f of the CO2 telecentric scanning field lens satisfies the following relationship: -0.6 <f1 / f<-0.25,0.3<f2 / f<0.65,0.9<f3 / f<1.3。

[0038] In the above embodiment, the total focal length of the CO2 telecentric scanning field lens is f, where the focal lengths of the first lens G1, the second lens G2, and the third lens G3 are f1, f2, and f3 respectively. These lenses satisfy a specific relationship with the total focal length of the entire system: -0.6 < f1 / f < -0.25, 0.3 < f2 / f < 0.65, 0.9 < f3 / f < 1.3. This means that the first lens G1 has a negative optical power and is used to initially diverge the incident light beam; the second lens G2 has a positive optical power and is responsible for initially converging the light rays, while the third lens G3 also has a positive optical power and further enhances the converging effect of the light rays; the first lens G1, the second lens G2, the third lens G3, and the protective mirror SG are all made of zinc selenide material with a refractive index of 2.4, which helps to improve the stability and performance of the optical system. The focal length of the entire field lens is set to 100 mm and is suitable for CO2 lasers with a wavelength of 9.6 μm. The designed telecentricity of this system is 2.4°, ensuring that within the entire optical scanning angle range of ±21°, the light rays are perpendicular to the processing plane, thus enabling high-precision laser processing. The diameter of the incident light beam is 20 mm, and uniform focusing can be maintained within a scanning range of 50 mm × 50 mm. The size of the focused spot is controlled between 84 - 86 μm through calibration and optimization, not only ensuring the perpendicular incidence of the light beam within the entire processing field of view but also significantly reducing the focus shift problem caused by traditional lenses, and significantly improving the drilling quality and production efficiency.

[0039] The surface curvature radius R, thickness T, and material refractive index Nd of each lens provided by the present utility model are shown in the following table:

[0040]

[0041] The above are only the preferred embodiments of the present utility model, and do not limit the patent scope of the present utility model. Any equivalent structural or equivalent process transformation made by using the content of the specification and attached drawings of the present utility model, or directly or indirectly applied in other related technical fields, shall be similarly included within the patent protection scope of the present utility model.

Claims

1. A CO2 telecentric scanning field mirror, applied to CO2 lasers, characterized in that, It includes a first lens, a second lens, a third lens, and a protective mirror arranged sequentially along the incident direction of the light beam; The first lens is a negative power lens with a meniscus structure, the second lens is a positive power lens with a meniscus structure, the third lens is a positive power lens with a biconvex structure, and the protective lens is a flat plate structure. The concave surfaces of the first lens and the second lens face the laser incident direction, respectively.

2. The CO2 telecentric scanning field mirror according to claim 1, characterized in that, The CO2 telecentric scanning field mirror also includes an entrance pupil plane and an image plane; The entrance pupil surface is located on the side of the first lens away from the second lens, and the image surface is located on the side of the protective lens away from the third lens. The first interval between the entrance pupil surface and the first lens is 35 mm, the second interval between the first lens and the second lens is 1.2 mm, the third interval between the second lens and the third lens is 29 mm, the fourth interval between the third lens and the protective lens is 3 mm, and the fifth interval between the image surface and the protective lens is 123 mm.

3. The CO2 telecentric scanning field mirror according to claim 1, characterized in that, The radii of curvature on the front and rear sides of the first lens are -43mm and -205mm, respectively, and the thickness of the first center of the first lens is 5mm.

4. The CO2 telecentric scanning field mirror according to claim 1, characterized in that, The radii of curvature on the front and rear sides of the second lens are -164mm and -52mm, respectively, and the thickness of the second center of the second lens is 10.5mm.

5. The CO2 telecentric scanning field mirror according to claim 1, characterized in that, The radii of curvature on the front and rear sides of the third lens are 317mm and -317mm, respectively, and the thickness of the third center of the third lens is 10mm.

6. The CO2 telecentric scanning field mirror according to claim 1, characterized in that, The thickness of the fourth center of the protective mirror is 3mm.

7. The CO2 telecentric scanning field lens according to any one of claims 1-6, characterized in that, The total focal length of the CO2 telecentric scanning field lens is f, and the focal lengths of the first lens, the second lens, and the third lens are f1, f2, and f3, respectively. These focal lengths satisfy the following relationship with the total focal length f of the CO2 telecentric scanning field lens: -0.6 <f1 / f<-0.25,0.3<f2 / f<0.65,0.9<f3 / f<1.3。 8. The CO2 telecentric scanning field lens according to any one of claims 1-6, characterized in that, The first lens, the second lens, the third lens, and the protective lens are all made of zinc selenide lenses.

9. The CO2 telecentric scanning field lens according to any one of claims 1-6, characterized in that, The refractive index of the first lens, the second lens, the third lens, and the protective mirror is all 2.

4.

10. The CO2 telecentric scanning field mirror according to claim 1, characterized in that, The entire CO2 telecentric scanning field lens has a focal length of 100mm, a wavelength of 9.6μm, a telecentricity of 2.4°, an optical scanning angle of ±21°, an incident beam diameter of 20mm, a scanning range of 50mm*50mm, and a focused spot size of 84-86μm.

Images