Laser processing system and method for adjusting beam characteristics thereof

Abstract

A laser processing system includes: an output fiber configured to be adapted to emit a laser beam onto a workpiece and having a core fiber and a loop fiber surrounding the core fiber; a plurality of fiber lasers as laser sources, one or more of which are configured to be adapted to provide a core beam for transmission within the core fiber, and the other one or more of which are configured to be adapted to provide a ring beam for transmission within the ring fiber; and a beam characteristic adjustment unit configured to be adapted to individually adjust at least one beam characteristic of each of the core beam and the ring beam. According to the present invention, by individually adjusting at least one beam characteristic of each of the core beam and the ring beam in the coaxial output fiber of the laser processing system, various laser parameters of the laser beam output by the output fiber can be adjusted. Therefore, the flexibility of the laser processing system is improved, and various requirements in laser processing application can be met. The invention also relates to a method for adjusting a beam characteristic of a laser processing system.

Description

Technical Field

[0001] This invention relates to the field of laser processing equipment, and in particular to a laser processing system and a method for adjusting the beam characteristics of the laser processing system. Background Technology

[0002] In today's laser processing, high-power laser output is increasingly required. This high-power output is typically provided by a high-power fiber laser system, which combines multiple lower-power laser modules. For example, four 3kW fiber lasers can be combined using a fiber combiner to achieve a 12kW high-power output. Fiber combiners can be manufactured based on mode conversion principles to provide the required output beam quality. With the expansion of application demands, the requirements for fiber combiners are becoming increasingly diverse and specialized. For instance, in BrightLine Welding, which utilizes coaxial fiber, the coaxial fiber consists of a core fiber and a ring fiber surrounding the core fiber. The desired weld quality can be achieved by controlling the laser welding process by adjusting the laser energy density transmitted through the core fiber and / or the ring fiber. For such coaxial fibers (or ring-shaped fibers), due to the core-ring structure, traditional methods for adjusting laser parameters, especially the beam-parameter product (BPP), at the output of the fiber combiner are no longer applicable. This is because some adjustments can have uncontrollable effects on the beam in both the core and ring fibers simultaneously, while others cannot affect the core fiber within the ring-shaped fiber, leading to undesirable beam output. Therefore, these parameters often can only be determined through the fabrication of the fiber combiner. This places high demands on fiber combiner manufacturing; furthermore, once the fiber combiner is fabricated, many laser parameters, especially the BPP, are fixed and essentially cannot be adjusted further, thus limiting the application of laser processing systems with coaxial fibers. Furthermore, the adjustment of some laser parameters is not always unidirectional. For example, a smaller BPP value is not always better; rather, a suitable value is determined based on the actual processing application. Therefore, high-power laser processing systems that allow for flexible beam characteristic adjustment are even more necessary. Summary of the Invention

[0003] The purpose of this invention is to provide a laser processing system and a method for adjusting the beam characteristics of the laser processing system, so as to at least partially solve the problems existing in the prior art.

[0004] According to a first aspect of the present invention, a laser processing system is provided, comprising:

[0005] An output optical fiber is configured to emit a laser beam onto a workpiece for processing, and the output optical fiber has a central core fiber and a loop fiber surrounding the core fiber.

[0006] A plurality of fiber lasers serving as laser sources, wherein one or more of the plurality of fiber lasers are configured to provide a core beam propagating within the core fiber, and another one or more of the plurality of fiber lasers are configured to provide a ring beam propagating within the ring fiber; and

[0007] A beam characteristic adjustment unit, the beam characteristic adjustment unit being configured to individually adjust at least one beam characteristic of each of the core beam and the ring beam.

[0008] Using the laser processing system according to the first aspect of the present invention, multiple laser parameters of the laser beam output from the output fiber can be adjusted by individually adjusting at least one beam characteristic of the core beam and the ring beam, thereby improving the flexibility of the laser processing system to meet various needs in laser processing applications.

[0009] According to an exemplary embodiment, the at least one beam characteristic includes a beam parameter product. This embodiment allows for flexible adjustment of the beam parameter product (BPP) of the core beam and the ring beam of the laser beam output from the output fiber, enabling the laser processing system to meet a wider range of laser processing requirements.

[0010] According to an exemplary embodiment, the beam characteristic adjustment unit is configured to individually adjust at least one beam characteristic of the core beam before the core beam is coupled into the core fiber of the output fiber, and to individually adjust at least one beam characteristic of the ring beam after the ring beam is coupled into the ring fiber of the output fiber. Since the core fiber inside the output fiber is insensitive to external interference, this embodiment enables individual adjustment of at least one beam characteristic of the core beam by adjusting it before it is coupled into the core fiber of the output fiber, and allows for simple individual adjustment of at least one beam characteristic of the ring beam within the outer ring fiber by adjusting the entire output fiber after bundling.

[0011] According to an exemplary embodiment, the outputs of one or more of the plurality of fiber lasers providing the core beam are coupled to the core fiber of the output fiber via a common core input fiber, and the beam characteristic adjustment unit includes: a first adjustment device configured to operate with respect to the core input fiber to change at least one beam characteristic of the core beam transmitted within the core input fiber; and a second adjustment device configured to operate with respect to the output fiber to change at least one beam characteristic of the ring beam transmitted within the ring fiber of the output fiber. Through this embodiment, the beam characteristics of the core beam and the ring beam can be adjusted respectively by means of the first and second adjustment devices of the beam characteristic adjustment unit.

[0012] According to an exemplary embodiment, the first adjustment device is an optical fiber clamp configured to form a long-period grating together with the core input fiber by clamping the core input fiber and holding the clamped core input fiber in a predetermined shape. This embodiment allows for the simple adjustment of the beam characteristics, particularly the beam percentage (BPP), of the core beam using the optical fiber clamp.

[0013] According to an exemplary embodiment, the fiber optic clamp has a pair of opposing corrugated clamping surfaces suitable for clamping the fiber. The number of arcuate segments on the corrugated clamping surfaces, the radius of curvature of each arcuate segment, and the value of the central angle depend on the transmission rate and divergence of the core beam after passing through the long-period grating. Through this embodiment, the parameters of the fiber optic clamp can be determined according to the desired transmission rate and BPP of the core beam, and thus various desired transmission rates and BPPs of the core beam can be obtained by changing the parameters of the fiber optic clamp.

[0014] According to an exemplary embodiment, the fiber optic clamp has a first clamp and a second clamp, a pair of opposing corrugated clamping surfaces formed on the first clamp and the second clamp, respectively, and the first clamp is configured to move and be fixed between a first position in which the second clamp makes surface contact with the pair of opposing corrugated clamping surfaces and a second position spaced a predetermined distance from the pair of opposing corrugated clamping surfaces. With this embodiment, the transmittance and beam percentage (BPP) of the core beam within it can be adjusted in a simple manner by clamping the core input fiber between the first clamp and the second clamp.

[0015] According to an exemplary embodiment, the second clamping block has a bearing surface for supporting the first clamping block and a boss portion protruding from the bearing surface. A corrugated clamping surface of the second clamping block is formed on the side of the boss portion facing the first clamping block. The first clamping block is configured to slide and be fixed along the bearing surface of the second clamping block between a first position and a second position. This embodiment provides a fiber optic clamp with a simple structure and easy operation.

[0016] According to an exemplary embodiment, both the first clamping block and the second clamping block are formed as basic plates and placed opposite each other. The corrugated clamping surfaces are respectively formed on the opposing surfaces of the first clamping block and the second clamping block. The first clamping block and the second clamping block cooperate with each other through a guiding and fixing structure, allowing the first clamping block to move and be fixed relative to the second clamping block between a first position and a second position. This embodiment provides another simple and easy-to-operate fiber optic clamp.

[0017] According to an exemplary embodiment, the second adjustment device is an optical fiber winding tray, on which the output optical fiber is wound. This embodiment allows for the simple adjustment of at least one beam characteristic, particularly the BPP, of the loop beam within the loop fiber by bending the output optical fiber, without interfering with the core beam within the core fiber.

[0018] According to an exemplary embodiment, the winding radius of the fiber winding portion depends on the tensile strength and / or radius of the output fiber. This embodiment allows the winding radius of the fiber winding portion to be determined by the tensile strength and / or radius of the output fiber and the desired beam characteristics of the ring beam, thereby obtaining the desired beam characteristics of the ring beam.

[0019] According to an exemplary embodiment, the fiber winding portion is detachably fixed to the fiber winding tray. This embodiment allows for easy replacement of fiber winding portions with different winding radii, thereby enabling a wide range of adjustments to the beam characteristics of the ring beam.

[0020] According to an exemplary embodiment, the fiber laser is a kilowatt-level fiber laser.

[0021] According to an exemplary embodiment, the core fiber diameter / ring fiber diameter of the output fiber is 100 / 300μm or 100 / 600μm.

[0022] According to an exemplary embodiment, the fiber laser pigtail has a core / cladding diameter of 20 / 250 μm and a core / cladding numerical aperture of 0.07.

[0023] According to an exemplary embodiment, the laser processing system further includes an optical fiber combiner for combining the core beam and the ring beam provided by the plurality of fiber lasers into the output optical fiber.

[0024] According to an exemplary example, the fiber combiner is an (N+1)×1 combiner comprising N ring beam input fibers and 1 core beam input fiber, wherein the ring beam input fibers are respectively coupled to one or more of the plurality of fiber lasers providing the ring beam, and the core beam input fiber is coupled to a core input fiber or the core input fiber, wherein N is an integer, N>1, and in particular N=6.

[0025] According to an exemplary example, the core / cladding diameter of each input fiber of the fiber combiner is 20 / 250 μm, and the core / cladding numerical aperture is 0.07.

[0026] According to an exemplary embodiment, the fiber combiner is detachably fixed to the fiber winding tray. This embodiment enables a more compact structure for the laser processing system.

[0027] According to a second aspect of the present invention, a method for adjusting the beam characteristics of a laser processing system is provided, the laser processing system being the laser processing system according to a first aspect of the present invention, the method comprising:

[0028] The parameters of the first and second adjustment devices of the beam characteristic adjustment unit are determined based on the laser beam parameters provided by the fiber laser and the parameters of the output fiber.

[0029] Before the core beam is coupled into the output fiber, at least one beam characteristic of the core beam is individually adjusted using the first adjustment device, and

[0030] The second adjustment device is used to act on the output optical fiber to individually adjust at least one beam characteristic of the ring beam.

[0031] Using the method according to the second aspect of the invention, at least one beam characteristic of the core beam and the ring beam output by the output fiber, which is a coaxial fiber, can be adjusted individually, thereby improving the flexibility of the laser processing system to meet various needs in laser processing applications.

[0032] According to one exemplary embodiment, the at least one beam characteristic includes a beam parameter product.

[0033] According to certain exemplary embodiments of the present invention, by using the beam characteristic adjustment unit of the laser processing system to individually adjust at least one beam characteristic of the core beam and the ring beam in the coaxial fiber of the laser processing system, it is possible to adjust various laser parameters, especially the beam parameter product (BPP), of the laser beam output from the coaxial fiber, thereby improving the flexibility of the laser processing system to meet various needs in laser welding applications. Attached Figure Description

[0034] The invention will now be described in more detail with reference to the accompanying drawings, which will provide a better understanding of its principles, features, and advantages. The drawings include:

[0035] Figure 1 A schematic diagram of the main parts of a laser processing system according to an exemplary embodiment of the present invention is shown;

[0036] Figure 2 A schematic cross-sectional view of the output fiber of a laser processing system according to an exemplary embodiment of the present invention is shown.

[0037] Figure 3 A schematic structural diagram of a laser processing system according to an exemplary embodiment of the present invention is shown;

[0038] Figure 4 A plan view of an fiber optic clamp serving as a first adjustment device in a beam characteristic adjustment unit of a laser processing system according to an exemplary embodiment of the present invention is shown; and

[0039] Figure 5 The arcuate section of the wavy clamping surface of the fiber optic clamp and its dimensional parameters are schematically shown.

[0040] Figure 6A A plan view of an optical fiber clamp serving as a first adjustment device in a beam characteristic adjustment unit of a laser processing system according to another exemplary embodiment of the present invention is shown. Figure 6B A three-dimensional view of the fiber optic clamp is shown. Detailed Implementation

[0041] To make the technical problems to be solved, the technical solutions, and the beneficial technical effects of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and several exemplary embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of protection of this invention.

[0042] Figure 1 A schematic diagram of the main parts of a laser processing system 100 according to an exemplary embodiment of the present invention is shown. Figure 1As shown, the laser processing system 100 according to the present invention is a high-power fiber laser system composed of several low-power fiber lasers 1 bundled together, and uses coaxial fiber as the output fiber 2, making it suitable for ring-core tunable welding technology. The output fiber 2 emits a laser beam onto the workpiece for processing, precision machining, particularly welding, or additive manufacturing of the workpiece. The coaxial fiber is also called W-type fiber, ring-spot fiber, or 2-in-1 fiber. Figure 2 A schematic diagram of the cross-sectional view of output fiber 2 is shown. (For example...) Figure 1 and Figure 2 As shown, the coaxial fiber / output fiber 2 includes a central core fiber 21 and a ring fiber 22 surrounding the core fiber 21, in which laser beams can be transmitted individually or simultaneously. In this text, the laser beam transmitted within the core fiber 21 is called the core beam, and the laser beam transmitted within the ring fiber 22 is called the ring beam. Among several fiber lasers 1, one or more fiber lasers 1 ( Figure 1 The diagram schematically illustrates one fiber laser 1 configured to provide a core beam propagating within the core fiber 21, and one or more other fiber lasers 1 configured to provide a ring beam propagating within the ring fiber 22. By changing the number and / or power rating of the fiber lasers 1 providing the core and ring beams, the power ratio of the core beam to the ring beam output from the output fiber 2 can be altered to obtain the desired output beam, thus achieving advantages such as reduced spatter and improved surface finish in various processing steps. Besides adjusting the power distribution of the core and ring beams as needed, further improvements in processing quality may require appropriate adjustment of other beam characteristics to obtain ideal laser parameters. As mentioned earlier, due to the core-ring structure, conventional beam characteristic adjustment methods are no longer applicable to the output fiber 2. The laser processing system 100 according to the present invention further includes a beam characteristic adjustment unit 3, configured to individually adjust at least one beam characteristic of each of the core and ring beams, thereby enabling the adjustment of multiple laser parameters of the output beam from the output fiber 2 to meet more processing requirements.

[0043] A representative example of beam characteristics that need adjustment is the product of transmittance and beam parameters, hereinafter referred to as BPP. As mentioned above, for coaxial fiber, due to structural reasons, the BPP parameter can often only be determined through the manufacture of the fiber combiner and is basically not subject to further adjustment. However, in the laser processing system 100 according to the present invention, the beam characteristic adjustment unit 3 can adjust the BPP parameter separately for the core beam and the ring beam.

[0044] Figure 3 A schematic structural diagram of a laser processing system 100 according to an exemplary embodiment of the present invention is shown. Figure 3In the exemplary embodiment shown, the laser processing system 100 further includes an optical fiber combiner 4, which combines the core beams and ring beams provided by multiple fiber lasers 1 to the output optical fiber 2. The beam characteristic adjustment unit 3 of the laser processing system 100 according to the present invention is adapted to perform at least one beam characteristic adjustment, particularly BPP adjustment, on the core beam before it is combined by the optical fiber combiner 4, and to operate the output optical fiber 2 as a whole after it is combined by the optical fiber combiner 4 to achieve at least one beam characteristic adjustment, particularly BPP adjustment, on the ring beam.

[0045] Specifically, in Figure 3 In the illustrated embodiment, the output of one or more fiber lasers 1 providing the core beam is first coupled to a core input fiber 5. This includes two scenarios: first, when there is only one fiber laser 1 providing the core beam, the pigtail of that single fiber laser 1 can be directly coupled to the core input fiber 5, for example, via fusion splicing, without the need for a combiner; and second, when there are multiple fiber lasers 1 providing core beams, these multiple fiber lasers 1 can be combined to a core input fiber 5 using another combiner 6. The core input fiber 5 is coupled to the core fiber 21 of the output fiber 2 via the fiber combiner 4, meaning the core beam transmitted within the core input fiber 5 is coupled into the core fiber 21 of the output fiber 2 via the fiber combiner 4. Furthermore, one or more fiber lasers 1 providing the ring beam are coupled to the ring fiber 22 of the output fiber 2 via the fiber combiner 4, meaning the laser beams provided by these fiber lasers 1 are directly coupled into the ring fiber 22 of the output fiber 2 as ring beams via the fiber combiner 4. If necessary, when multiple fiber lasers 1 providing ring beams exist, these multiple fiber lasers 1 can also be combined into a single ring input fiber via an additional combiner (not shown). This ring input fiber is then coupled to the ring fiber 22 of the output fiber 2 via the fiber combiner 4. With this configuration, the beam characteristics of the ring beam can be individually adjusted (e.g., by operating the ring input fiber using the beam characteristic adjustment unit 3) before the ring beam is coupled into the ring fiber 22 of the output fiber 2. Figure 1As shown, the system is configured to allow for individual beam characteristic adjustment of the ring beams before beam combining using the beam characteristic adjustment unit 3. However, in this embodiment, one or more fiber lasers 1 providing the ring beams can be directly coupled to the ring fiber 22 of the output fiber 2 via the fiber combiner 4. Here, the fiber combiner 4 can be an (N+1)×1 signal combiner, comprising N ring beam input fibers 42 and one core beam input fiber 41. The ring beam input fibers 42 are coupled to the pigtails of one or more fiber lasers 1 providing the ring beams, and the core beam input fiber 41 is coupled to the core input fiber 5 or is the core input fiber 5 itself. Here, N is an integer, specifically N=6, and the N ring beam input fibers 42 are arranged symmetrically around the core beam input fiber 41.

[0046] The beam characteristic adjustment unit 3 includes: a first adjustment device 31 configured to operate on the core input fiber 5 to change at least one beam characteristic, particularly the beam percentage point (BPP), of the core beam transmitted within the core input fiber 5; and a second adjustment device 32 configured to operate on the output fiber 2 to change at least one beam characteristic, particularly the beam percentage point (BPP), of the ring beam transmitted within the ring fiber 22 of the output fiber 2, particularly changing the BPP of the ring beam transmitted only within the ring fiber 22 of the output fiber 2.

[0047] In a particularly preferred embodiment, the first adjustment device 31 of the beam characteristic adjustment unit 3 is an optical fiber clamp. Figure 4 A plan view of an optical fiber clamp 310 as a first adjustment device 31 according to an exemplary embodiment is shown. Figure 4 As shown, the fiber optic clamp 310 has a pair of opposing corrugated clamping surfaces 311 and 312 suitable for clamping optical fibers, a first clamping block 313, and a second clamping block 314. The pair of opposing corrugated clamping surfaces 311 and 312 are respectively formed on the first clamping block 313 and the second clamping block 314. The first clamping block 313 is configured to move and be fixed relative to the second clamping block 314 between a first position where it makes surface contact with the pair of opposing corrugated clamping surfaces 311 and 312 and a second position where the pair of opposing corrugated clamping surfaces 311 and 312 are spaced apart by a predetermined distance. The corrugated clamping surfaces 311 and 312 each have multiple arcuate segments, and the arcuate segments of the corrugated clamping surfaces 311 and 312 can be shaped to fit each other at the first position. The fiber clamp 310 constructed in this way is suitable for clamping and releasing the fiber between a pair of opposing wavy clamping surfaces 311, 312, and is thus configured to form a long-period grating together with the clamped core input fiber 5 by clamping the core input fiber 5 and holding the clamped core input fiber 5 in a predetermined shape, especially a wavy shape, thereby enabling the BPP of the core beam within the core input fiber 5 to be adjusted by the long-period grating. Figure 5The arcuate sections of the wavy clamping surfaces 311 and 312 of the fiber optic clamp 310 and their dimensional parameters are illustrated in an exaggerated manner. When selecting or designing the fiber optic clamp 310, the number Nx of the arcuate sections of the wavy clamping surfaces 311 and 312, the radius of curvature R of each arcuate section, and the value of the central angle θ can be determined based on the transmission rate and divergence of the core beam of the corresponding wavelength provided by the fiber laser 1 after passing through the constructed long-period grating. The desired transmission rate and BPP of the core beam can then be obtained with the help of the corresponding long-period grating. Based on experience, for lasers in commonly used wavelength ranges, in general laser processing applications, the number Nx of the arcuate sections of the wavy clamping surfaces 311 and 312 is usually selected from 3 to 9, the radius of curvature R ranges from 15 to 40 mm, and the central angle θ ranges from 5 to 25 degrees. In addition, it should be noted that the minimum bending radius of the clamped optical fiber, here referring to the core input fiber 5, is limited by its tensile strength. If the bending radius is too small, it will lead to additional bending losses and thus affect the performance of the system. Therefore, the minimum curvature radius R of the arc section should be more than 200 times the radius of the corresponding core input fiber 5 to avoid additional bending losses caused by an excessively small bending radius.

[0048] Figure 6A and Figure 6B Plan view and perspective view of the fiber optic clamp 310 as a first adjustment device 31 according to another exemplary embodiment are shown, wherein the functionally identical parts are used for... Figure 4 The same reference numerals are used. Figure 6A and 6B The fiber optic clamp shown Figure 4 The only difference between the fiber optic clamps shown is the specific shape of the first clamp 313 and the second clamp 314, and the resulting different fit and operation between them.

[0049] for Figure 4 The fiber optic clamp 310 shown has a second clamping block 314 with a bearing surface for supporting a first clamping block 313 and a boss portion protruding from the bearing surface. A corrugated clamping surface 312 of the second clamping block 314 is formed on the side of the boss portion facing the first clamping block 313. The first clamping block 313 is configured to slide and be fixed between a first position and a second position (in the vertical direction shown in the figure) along the bearing surface of the second clamping block 314. Sliding and fixing are achieved, for example, through guide holes in the first clamping block 313 and bolts threaded through the guide holes onto the second clamping block 314.

[0050] for Figure 6A and Figure 6BThe fiber optic clamp 310 shown has a first clamping block 313 and a second clamping block 314 formed as basic plates. The two plate-shaped clamping blocks 313 and 314 are placed opposite each other, and corrugated clamping surfaces 311 and 312 are formed on the opposing surfaces of the two clamping blocks 313 and 314, respectively. The two clamping blocks 313 and 314 cooperate with each other through a guiding and fixing structure, allowing the first clamping block 313 to move and be fixed relative to the second clamping block 314 between a first position and a second position. The guiding and fixing structure can be, for example, a bolt-and-screw hole structure at multiple locations (e.g., the four corners in the figure), thereby adjusting the relative position between the first clamping block 313 and the second clamping block 314 through threaded operation. Preferably, one clamp (exemplarily shown as the first clamp 313 in the figure) may have a boss portion extending toward the other clamp, and its corresponding wavy clamping surface (exemplarily shown as the wavy clamping surface 311 in the figure) is formed at least on the end face of the boss portion facing the other clamp. This design can compensate for the geometric height of the guide fixing structure, such as a bolt-and-screw structure, making the fiber clamp 310 more suitable for clamping fibers with small radial dimensions.

[0051] In a preferred embodiment, the second adjustment device 32 of the beam characteristic adjustment unit 3 is an optical fiber winding tray. The output optical fiber 2 is wound around the optical fiber winding portion of this tray, thereby simply adjusting the BPP of the ring beam within the ring optical fiber 22 of the output optical fiber 2 by means of the bending of the optical fiber as an adjustment mechanism, without affecting the core beam within the core optical fiber 21. The optical fiber winding portion can be formed as a simple columnar shape, a semi-cylindrical shape, or any other shape with an arc segment that allows the optical fiber to bend at the winding radius. The winding radius of the optical fiber winding portion (the bending radius of the output optical fiber 2) depends on the tensile strength and / or radius of the output optical fiber 2. Taking a coaxial optical fiber with a core / ring diameter of 100 / 600 μm as an example, extensive experiments have shown that for bending radii ranging from 80 mm to 220 mm, the adjustment range of the BPP of the beam within the ring optical fiber 22 can reach 3 mm·mrad. Furthermore, the minimum bending radius of the output optical fiber 2 is limited by its tensile strength; a bending radius that is too small will lead to additional bending losses, thus affecting the performance of the system. Based on experience, the minimum bending radius of the output fiber 2 should be selected to be more than 200 times its radius to avoid additional bending losses.

[0052] In one optional embodiment, the fiber winding portion is detachably fixed to the fiber winding tray, thereby allowing for the replacement of fiber winding portions with different radius sizes as needed. Furthermore, in another optional embodiment, the fiber combiner 4 can be detachably fixed to the fiber winding tray, or the fiber winding tray itself can serve as the fiber combiner tray for the fiber combiner 4.

[0053] In an optional embodiment, the fiber laser 1 is a kilowatt-level fiber laser, such as a 3kW fiber laser.

[0054] In an optional embodiment, the core / cladding diameter of the pigtail of the fiber laser 1 and / or the individual input fibers 41, 42 of the fiber combiner 4 is 20 / 250 μm, and the core / cladding numerical aperture is 0.07.

[0055] In an optional embodiment, the core fiber diameter / ring fiber diameter of the output fiber 2 is 100 / 300μm or 100 / 600μm.

[0056] The foregoing has described exemplary embodiments of the laser processing system 100 according to the present invention, but the laser processing system 100 according to the present invention is not limited thereto. For example, the beam characteristic adjustment unit 3 may also include any suitable plurality of other adjustment devices for performing various other beam characteristic adjustments on the core beam and / or ring beam before and / or after beam combining, such as other fiber bending / stretching components, heating devices, piezoelectric devices, acousto-optic transducers, etc., or any combination thereof. The adjusted beam characteristics may also include beam diameter, beam divergence distribution, intensity distribution, M 2 Factors, numerical aperture, light intensity profile, power density profile, radial beam position, spot size, or any combination thereof.

[0057] The present invention also relates to a method for adjusting the beam characteristics of a laser processing system 100, the method comprising: determining the parameters of a first adjustment device 31 and a second adjustment device 32 of a beam characteristic adjustment unit 3 based on the laser beam parameters of a fiber laser 1, the parameters of an output fiber 2, and the parameters of the output laser beam of the desired output fiber 2; adjusting at least one beam characteristic, particularly BPP, of the core beam individually using the first adjustment device 31 before the core beam is coupled into the output fiber 2; and applying the second adjustment device 32 to the output fiber 2 to adjust at least one beam characteristic, particularly BPP, of the ring beam individually.

[0058] Although specific embodiments of the invention have been described in detail herein, they are given for illustrative purposes only and should not be construed as limiting the scope of the invention. Various substitutions, alterations, and modifications are conceived without departing from the spirit and scope of the invention.

[0059] Reference tag list

[0060] 1. Fiber laser

[0061] 2. Output optical fiber

[0062] 21-core optical fiber

[0063] 22 rings of optical fiber

[0064] 3-beam characteristic adjustment unit

[0065] 31 First Adjustment Device

[0066] 32 Second Adjustment Device

[0067] 310 Fiber Optic Clamp

[0068] 311, 312 wavy clamping surfaces

[0069] 313 First clamping block

[0070] 314 Second clamping block

[0071] 4 Fiber optic combiner

[0072] 41-core beam input fiber

[0073] 42-ring beam input fiber

[0074] 5-core input fiber

[0075] 6. Another bundle combiner

[0076] 100 laser processing system.

Claims

1. A laser processing system (100), comprising: Output fiber (2), the output fiber (2) is configured to emit a laser beam onto the workpiece to process the workpiece, and the output fiber (2) has a core fiber (21) at the center and a loop fiber (22) surrounding the core fiber (21); A plurality of fiber lasers (1) serving as laser sources, wherein one or more of the plurality of fiber lasers (1) are configured to provide a core beam transmitted within the core fiber (21), and another one or more of the plurality of fiber lasers (1) are configured to provide a ring beam transmitted within the ring fiber (22); and A beam characteristic adjustment unit (3) is configured to individually adjust at least one beam characteristic of the core beam and the ring beam.

2. The laser processing system (100) according to claim 1, wherein, The at least one beam characteristic includes the product of beam parameters.

3. The laser processing system (100) according to claim 1 or 2, wherein, The beam characteristic adjustment unit (3) is configured to individually adjust at least one beam characteristic of the core beam before the core beam is coupled into the core fiber (21) of the output fiber (2), and to individually adjust at least one beam characteristic of the ring beam after the ring beam is coupled into the ring fiber (22) of the output fiber (2).

4. The laser processing system (100) according to claim 3, wherein, The outputs of one or more of the plurality of fiber lasers (1) providing the core beam are coupled to the core fiber (21) of the output fiber (2) via a common core input fiber (5), and The beam characteristic adjustment unit (3) includes: A first adjustment device (31) is configured to operate with respect to the core input fiber (5) to change at least one beam characteristic of the core beam transmitted within the core input fiber (5); and A second adjustment device (32) is configured to operate on the output fiber (2) to change at least one beam characteristic of the ring beam transmitted within the ring fiber (22) of the output fiber (2).

5. The laser processing system (100) according to claim 4, wherein, The first adjustment device (31) is an optical fiber clamp (310), which is configured to form a long-period grating together with the core input fiber (5) by clamping the core input fiber (5) and holding the clamped core input fiber (5) in a predetermined shape.

6. The laser processing system (100) according to claim 5, wherein, The fiber clamp (310) has a pair of opposing wavy clamping surfaces (311, 312) suitable for clamping the fiber. The number (Nx) of the arcuate segments of the wavy clamping surfaces (311, 312), the radius of curvature (R) of each arcuate segment, and the value of the central angle (θ) depend on the transmission rate and divergence of the core beam after passing through the long-period grating.

7. The laser processing system (100) according to claim 6, wherein, The fiber optic clamp (310) has a first clamping block (313) and a second clamping block (314), and a pair of opposing wavy clamping surfaces (311, 312) are formed on the first clamping block (313) and the second clamping block (314), respectively. The first clamping block (313) is configured to move and be fixed relative to the second clamping block (314) between a first position in which it makes surface contact with the pair of opposing wavy clamping surfaces (311, 312) and a second position that is spaced a predetermined distance from the pair of opposing wavy clamping surfaces (311, 312).

8. The laser processing system (100) according to claim 7, wherein, The second clamping block (314) has a bearing surface for supporting the first clamping block (313) and a boss portion protruding from the bearing surface. A wavy clamping surface (312) of the second clamping block (314) is formed on the side of the boss portion facing the first clamping block (313). The first clamping block (313) is configured to slide and be fixed along the bearing surface of the second clamping block (314) between a first position and a second position; or The first clamping block (313) and the second clamping block (314) are both formed as basic plates and placed opposite each other. The wavy clamping surfaces (311, 312) are respectively formed on the opposing surfaces of the first clamping block (313) and the second clamping block (314). The first clamping block (313) and the second clamping block (314) cooperate with each other through the guiding and fixing structure between them, so that the first clamping block (313) can move and be fixed relative to the second clamping block (314) between the first position and the second position.

9. The laser processing system (100) according to claim 4, wherein, The second adjustment device (32) is an optical fiber winding tray, and the output optical fiber (2) is wound on the optical fiber winding portion of the optical fiber winding tray.

10. The laser processing system (100) according to claim 9, wherein, The winding diameter of the optical fiber winding portion depends on the tensile strength and / or diameter of the output optical fiber (2); The fiber optic winding portion is detachably fixed to the fiber optic winding tray.

11. The laser processing system (100) according to any one of claims 1 to 10, wherein, The fiber laser (1) is a kilowatt-level fiber laser; and / or The core fiber diameter / ring fiber diameter of the output optical fiber (2) is 100 / 300μm or 100 / 600μm; and / or The fiber laser (1) has a core / cladding diameter of 20 / 250 μm and a core / cladding numerical aperture of 0.

07.

12. The laser processing system (100) according to any one of claims 1 to 10, wherein, The laser processing system (100) further includes a fiber combiner (4) for combining the core beam and the ring beam provided by the plurality of fiber lasers (1) into the output fiber (2), and: The fiber combiner (4) is an (N+1)×1 combiner, comprising N ring beam input fibers (42) and one core beam input fiber (41). The ring beam input fiber (42) is coupled to one or more of the plurality of fiber lasers (1) that provide the ring beam. The core beam input fiber (41) is coupled to a core input fiber (5) or the core input fiber (5), wherein N is an integer, N>1, and in particular N=6; and / or The core / cladding diameter of each input fiber of the fiber combiner (4) is 20 / 250 μm, and the numerical aperture of the core / cladding is 0.

07.

13. A method for adjusting the beam characteristics of a laser processing system, said laser processing system being a laser processing system (100) according to any one of claims 1 to 12, the method comprising: Based on the laser beam parameters provided by the fiber laser (1) and the parameters of the output fiber (2), determine the model parameters of the first adjustment device (31) and the second adjustment device (32) of the beam characteristic adjustment unit (3). Before the core beam is coupled into the output fiber (2), at least one beam characteristic of the core beam is individually adjusted using the first adjustment device (31), and The output optical fiber (2) is acted upon using the second adjustment device (32) to individually adjust at least one beam characteristic of the ring beam.

14. The method according to claim 13, wherein, The at least one beam characteristic includes the product of beam parameters.

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