Laser filament cutting device

Abstract

The present invention discloses a laser filament cutting device, which includes an axicon, a long-focal-length lens, a galvanometer assembly, and a field lens. The laser beam is converted into a Bessel beam by the axicon, which is then projected onto the galvanometer assembly via the long-focal-length lens. The Bessel beam is deflected by the galvanometer assembly, and then interfered with by the field lens to form a linear focus with a long focal depth, thereby achieving rapid cutting on the surface of a workpiece. The Bessel beam has a long focal depth. After being reflected by the galvanometer assembly, it passes through the field lens and is projected onto the workpiece surface. Even if the beam deflects, causing the distance between the field lens and the projection point to change, the projection point remains within the focal depth range, and the cutting effect is not affected.

Description

Technical Field

[0001] The present invention relates to the field of laser cutting, in particular to a laser filament cutting device. Background Art

[0002] With the development of science and technology, transparent materials such as glass and sapphire have been widely used in consumer electronics fields such as fingerprint recognition buttons, camera protection lenses, tablets and smartphone screens. Before applying transparent materials to products, they need to be cut and processed. Due to the high hardness of transparent materials, lasers are mostly used in the existing technology to cut transparent materials. The Bessel cutting lens can convert the Gaussian beam of the laser from a circular beam into a line focal point formed by the interference of the Bessel beam, which can be used for filament cutting of materials such as sapphire and glass. In actual cutting applications, existing applications either achieve the purpose of irregular cutting by moving the Bessel cutting lens or by moving the processing plane. Whether it is moving the Bessel cutting lens or moving the processing plane, the processing efficiency is relatively low. Summary of the Invention

[0003] The main purpose of the present invention is to provide a laser filament cutting device, which aims to solve the problem of low efficiency of laser filament cutting of materials such as sapphire and glass in the prior art.

[0004] To achieve the above object, the present invention proposes a laser filament cutting device based on the optical path principle of a Bessel cutting lens, comprising an axicon, a long focal length lens, a galvanometer assembly and a field lens arranged in sequence along the optical path;

[0005] The axicon is used to convert the collimated light beam into a Bessel light beam. The Bessel light beam is irradiated on the galvanometer assembly through the long focal length lens. The galvanometer assembly is used to control the deflection of the Bessel light beam. The field lens is used to interfere and focus the Bessel light beam on the workpiece.

[0006] In one embodiment, the long focal length lens is located at the end of the Bessel focal depth of the axicon, and the focusing point of the long focal length lens is located between the galvanometer assembly and the field lens.

[0007] In one embodiment, the galvanometer assembly includes a first galvanometer for deflecting the Bessel beam in a first plane, and a second galvanometer for deflecting the Bessel beam in a second plane, wherein the second plane is perpendicular to the first plane.

[0008] In one embodiment, the laser filament cutting device further comprises a laser generator and a beam expander, and the laser emitted by the laser generator is incident on the axicon through the beam expander.

[0009] In one embodiment, the laser beam emitted by the laser generator includes a Gaussian beam, a flat-top beam, or a multi-mode beam, and the laser light generated by the laser generator includes ultraviolet light, infrared light, or green light.

[0010] In one embodiment, the cone angle α of the axicon is less than 30°.

[0011] In one embodiment, the diameter of the laser spot incident on the axicon is less than 8 mm.

[0012] In one embodiment, the field lens comprises a flat-field focusing lens, and the focal length of the field lens is greater than 80 mm.

[0013] In one embodiment, the laser filament cutting device further comprises a laser anti-reflection film coated on the surface of the axicon.

[0014] The present invention utilizes a laser filamentation cutting device comprising an axicon, a long-focal-length lens, a galvanometer assembly, and a field lens. The laser beam is converted by the axicon into a Bessel beam, which is then projected onto the galvanometer assembly via the long-focal-length lens. The galvanometer assembly controls the deflection of the Bessel beam, which is then interfered with by the field lens to form a linear focus with a long focal depth. This allows for rapid filamentation cutting on a workpiece surface. Furthermore, the Bessel beam has a long focal depth. After being reflected by the galvanometer assembly and projected onto the workpiece surface through the field lens, even if the beam deflects, causing the distance between the field lens and the projection point to change, the projection point remains within the focal depth, unaffecting the cutting effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. 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 the structures shown in these drawings without paying any creative work.

[0016] Figure 1 This is a schematic structural diagram of an embodiment of a laser filament cutting device according to the present invention;

[0017] Figure 2 This is a schematic structural diagram of another embodiment of the laser filament cutting device of the present invention.

[0018] Description of Figure Numbers:

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[0020]

[0021] The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0023] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indications will also change accordingly.

[0024] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of such features. In addition, if the meaning of "and / or" appearing in the full text is to include three parallel schemes, taking "A and / or B" as an example, it includes scheme A, or scheme B, or a scheme in which A and B are satisfied at the same time. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0025] The present invention proposes a laser filament cutting device, referring to Figure 1 and Figure 2The laser filament cutting device comprises an axicon 10, a long focal length lens 20, a galvanometer assembly 30, and a field lens 40, arranged sequentially along the optical path. The axicon 10 is used to convert a collimated light beam into a Bessel beam, the long focal length lens 20 focuses the Bessel beam, the galvanometer assembly 30 is used to control the deflection of the Bessel beam, and the field lens 40 is used to cause the Bessel beam to interfere with each other, forming a linear focus with a long focal depth. The long focal length lens 20 is located at the end of the Bessel focal depth of the axicon 10, and the focal point of the long focal length lens 20 is located between the galvanometer assembly 30 and the field lens 40. This laser filament cutting optical path overcomes the short focal depth (generally less than 1 mm) of laser cutting. The focal depth of the laser filament cutting device of the present invention is greater than 5 mm, enabling cutting with a long focal depth and suitable for thicker workpiece materials. In addition, the galvanometer assembly 30 can be used to control the deflection of the Bessel beam, achieving rapid movement of the light spot on the projection surface. Galvanometers typically operate at speeds of up to 10m / s, such as the ExtraScan10 model. Mobile platforms, such as the ONE-XY60 XY platform, can reach speeds of up to 200mm / s. Galvanometers can control light deflection 50 times more efficiently than mobile platforms, further improving laser cutting efficiency.

[0026] The present invention utilizes a laser filamentation cutting device comprising an axicon 10, a long-focal-length lens 20, a galvanometer assembly 30, and a field lens 40. The laser beam is converted into a Bessel beam by the axicon 10. The Bessel beam is then projected onto the galvanometer assembly 30 via the long-focal-length lens. The galvanometer assembly 30 controls the deflection of the Bessel beam, which is then interfered with by the field lens 40 to form a linear focus with a long focal depth. The Bessel beam has a long focal depth. After being reflected by the galvanometer assembly 30, it passes through the field lens 40 and is projected onto the workpiece surface. Even if the beam deflects, causing the distance between the field lens 40 and the projection point to change, the projection point remains within the focal depth, unaffecting the cutting effect.

[0027] In one embodiment, the galvanometer assembly 30 includes a first galvanometer 31 for deflecting the Bessel beam within a first plane, and a second galvanometer 32 for deflecting the Bessel beam within a second plane perpendicular to the first plane. In this embodiment, the surface of the workpiece is a projection plane, and the first plane, the second plane, and the workpiece surface are mutually perpendicular to form a coordinate system. The first galvanometer 31 controls the movement of the light spot along the X-axis on the workpiece surface, and the second galvanometer 32 controls the movement of the light spot along the Y-axis on the workpiece surface, thereby achieving control of the coordinates of the light spot on the workpiece surface.

[0028] In one embodiment, the field lens 40 includes a flat-field focusing lens, which receives the Bessel light beam and focuses the interference lines of the Bessel light beam on the surface of the workpiece to be cut. The flat-field focusing lens, also known as the field lens 40 or the f-theta focusing lens, is a professional lens system whose purpose is to form a focused light spot of uniform size on the entire marking plane. With an ordinary single-piece convex lens, a circular focused light spot is formed only when the light passes perpendicularly through the center. When the light enters the ordinary single-piece convex lens at an angle, that is, the incident light is not coaxial. The focused light spot is definitely deformed. More importantly, the focus of the light is not in the focal plane when the light is perpendicular. The focal length changes with the deflection angle, so the focal position also changes. When the galvanometer scans, using the flat field lens 40 can obtain a flat image plane; in terms of aberration correction, it can compensate for the field curvature and distortion of the system.

[0029] In one embodiment, an axicon is a conical prism defined by its alpha angle and apex angle. A focusing lens, such as a plano-convex lens, a biconvex lens, or an aspheric lens, can focus light at a specific point on the optical axis. An axicon can focus light at multiple points on the optical axis. The light beam generated by the axicon passes through the optical axis. As the distance from the axicon to the image increases, the diameter of the resulting light ring increases, while the thickness of the light ring remains constant. This light beam exhibits the characteristics of a Bessel beam, with the intensity distribution along the beam propagation direction unchanged. A Bessel beam has a Bessel focal depth. The axicon 10 is made of fused silica. Specifically, fused silica, due to its low thermal expansion coefficient and stable chemical properties, exhibits a high melting temperature under laser light. In one embodiment, the laser filamentation cutting apparatus further includes a laser antireflection coating coated on the surface of the axicon 10. Specifically, because light waves, like mechanical waves, exhibit interference properties, an antireflection coating utilizes the principle of light interference. Light reflected from the front and back surfaces of the film interferes, reducing the intensity of the reflected light and thereby increasing the intensity of the transmitted light.

[0030] In one embodiment, the laser filament cutting apparatus further includes a beam expander 50 disposed on the light-entry side of the axicon 10. The beam expander 50 is a lens assembly capable of changing the laser beam diameter and divergence angle. The laser beam emitted by the laser has a certain divergence angle. For laser processing, only by adjusting the beam expander 50 to collimate the laser beam can a focusing lens be used to obtain a small, high-power density spot. In laser ranging, the beam expander 50 must maximize the laser's collimation to achieve ideal long-distance measurement results. The beam expander 50 can be used to change the beam diameter for use with different optical instruments and equipment. The beam expander 50, when used in conjunction with a spatial filter, can transform an asymmetric beam distribution into a symmetrical one, achieving a more uniform light energy distribution.

[0031] The present invention further provides a laser filament cutting device, comprising the aforementioned laser filament cutting device and a laser generator 60. The laser beam emitted by the laser generator 60 includes a Gaussian beam, a flat-top beam, or a multimode beam. The laser generator can be an ultraviolet laser, a green laser, or an infrared laser.

[0032] In one embodiment, the laser generator 60 may be a picosecond laser. The laser emitted by the laser generator 60 includes ultraviolet light with a wavelength of 355 nm, green light with a wavelength of 532 nm, or infrared light with a wavelength of 1064 nm.

[0033] In one embodiment, the beam expander 50 can be a 1 to 8 times beam expander 50. The light spot incident on the axicon 10 is smaller than 8 mm. The cone angle α of the axicon 10 is less than 30°. If the focal length of the long focal length lens 20 is 250 mm, the optical path distances between the long focal length lens 20 and the first galvanometer and the second galvanometer are both smaller than 250 mm. The optical path distance from the long focal length to the field lens 40 is greater than 250 mm. The focal length of the field lens 40 is greater than 80 mm. By adjusting the distance between the field lens 40 and the galvanometer, different focal depths can be obtained, and processing materials of different thicknesses can be cut.

[0034] The above descriptions are merely optional embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present description and drawings under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A laser filament cutting device, characterized in that: It includes an axicon, a long focal length lens, a galvanometer assembly and a field lens which are sequentially arranged along the optical path; The axicon is used to convert the collimated light beam into a Bessel light beam, the Bessel light beam is irradiated on the galvanometer assembly through the long focal length lens, the galvanometer assembly is used to control the deflection of the Bessel light beam, and the field lens is used to focus the interference line of the Bessel light beam on the workpiece; The long focal length lens is located at the end of the Bessel focal depth of the axicon, and the focusing point of the long focal length lens is located between the galvanometer assembly and the field lens; The field lens includes a flat-field focusing lens, which is arranged behind the galvanometer assembly and is used to compensate for pixel difference and focus the Bessel beam interference line on the surface of the workpiece to be cut. The focal length of the field lens is greater than 80 mm; The focal depth of the laser filament cutting device is greater than 5 mm.

2. The laser filament cutting device according to claim 1, characterized in that: The galvanometer assembly includes a first galvanometer for deflecting the Bessel beam in a first plane, and a second galvanometer for deflecting the Bessel beam in a second plane, wherein the second plane is perpendicular to the first plane.

3. The laser filament cutting device according to claim 1, characterized in that: The laser filament cutting device further comprises a laser generator and a beam expander. The laser emitted by the laser generator is incident upon the axicon through the beam expander.

4. The laser filament cutting device according to claim 3, characterized in that: The laser beam emitted by the laser generator includes a Gaussian beam, a flat-top beam or a multi-mode beam, and the laser generated by the laser generator includes ultraviolet light, infrared light or green light.

5. The laser filament cutting device according to claim 1, characterized in that: The cone angle α of the axicon is less than 30°.

6. The laser filament cutting device according to claim 1, characterized in that: The spot diameter of the laser beam incident on the axicon is less than 8 mm.

7. The laser filament cutting device according to claim 1, characterized in that: The laser filament cutting device further comprises a laser anti-reflection film coated on the surface of the axicon.

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