System and method for homogenizing a beam profile and / or for adjusting a beam quality of a laser beam

Abstract

The invention relates to a system (11) for homogenizing a beam profile and / or for adjusting a beam quality of a laser beam (12), said system having features of claim (1), and to a method for homogenizing a beam profile and / or for adjusting a beam quality of a laser beam (12), having features of the additional independent claim.

Description

[0001] 2023P00216WO 13.08.2025

[0002] Title: System and procedure for homogenizing a

[0003] Beam profile and / or for adjusting the beam quality of a laser beam

[0004] Description

[0005] The invention relates to a system for homogenizing a beam profile and / or for adjusting the beam quality of a laser beam with features of claim 1 and a method for homogenizing a beam profile and / or for adjusting the beam quality of a laser beam with features of the dependent claim.

[0006] In laser material processing, beam quality plays a crucial role in the processing results. Therefore, controllable beam quality is an important criterion. Beam quality is defined by the beam parameter product SPP = M 2 * X / n, where X is the wavelength and M 2The diffraction coefficient (or beam quality factor, by which the waist radius and the divergence angle of the laser beam are increased relative to the fundamental mode).

[0007] In this case, the ability to divide and fix the components is very difficult to achieve.

[0008] It is therefore an object of the present invention to provide a system and a method for homogenizing a beam profile and / or for adjusting the beam quality of a laser beam, wherein a simple, stable and cost-effective solution for adjusting the beam quality is provided.

[0009] The above problem is solved by a system for homogenizing a beam profile and / or for adjusting the beam quality of a laser beam having the features of claim 1.

[0010] The system includes a fiber. The fiber is configured to guide the laser beam. The fiber is configured, at least in sections, as a multi-mode fiber for the laser beam (or its wavelength).

[0011] The system includes a rotary device. The rotary device is configured to generate at least one bend along the fiber. Within the rotary device, the fiber is arranged helically (e.g., in the form of a helix or a spiral) along a longitudinal axis, at least in sections. The rotary device is configured to vary (or adjust) the pitch, radius, and / or pitch (or turn length) of the helical section of the fiber. The helical section can have a length ranging from 1 mm (millimeter) to 1 m (meter). The length of the helical section can range from a few millimeters to several meters.

[0012] This allows the beam profile of a laser beam to be adjusted simply, stably and cost-effectively.

[0013] The bending generated in the helical section exerts stress on the fiber. At large bending radii (i.e., with a smaller bend or fewer turns), this stress homogenizes the beam profile. At small bending radii (i.e., with a tighter bend or more turns), the stress increases the internal propagation angle in the fiber core, thus increasing or deteriorating the resulting beam parameter product (SPP). A desired homogenization can be achieved or adjusted by precisely controlling the bending and thus the SPP, particularly by decreasing the SPP.

[0014] In this context, homogenization refers to the standardization of the laser beam profile. For example, a Gaussian beam profile can be homogenized to a desired top-hat beam profile by selectively degrading the SPP (Specific Beam Profile). Homogenization of the beam profile can specifically mean that the intensity distribution at the focus is uniform, e.g., top-hat shaped. The beginning and end of the helical section of the fiber can be twisted relative to each other and, in particular, fixed in place to allow for precise and stable adjustment of the number of turns and thus the desired degree of SPP adaptation.

[0015] In this context, the radius refers to the distance between the fiber and the longitudinal axis. In other words, it is the distance of the fiber from the longitudinal axis along a direction perpendicular to the longitudinal axis. The pitch refers to the slope or steepness of the fiber along the longitudinal axis. The pitch refers to the distance by which the helical section of the fiber winds along the longitudinal axis during one complete rotation (or period).

[0016] The system can represent an optical laser system or form a component of an optical laser system.

[0017] The system can include a control unit for controlling the rotary device or for adjusting the pitch, radius, and / or thread height. This can be implemented, for example, via stored winding tables or by means of a measurement signal, which can be picked up at an output of the fiber.

[0018] The rotary device can be configured to adjust the radius within a range of 10 mm (millimeters) to 10 cm (centimeters). The rotary device can be configured to adjust the pitch within a range of 10 mm to 10 cm. The rotary device can be configured to maintain a constant pitch. The rotary device can be configured to maintain a constant lead. The rotary device can be configured to maintain a constant radius. The rotary device can be configured such that the pitch, lead, and / or radius vary (change) along the longitudinal axis (e.g., conical shape of the helical section of the fiber). The rotary device can be configured such that the radius of the helical section can be varied locally or overall, e.g., by inflating a guide.

[0019] According to a further development of the system, the rotating device can be designed such that the fiber extends (or winds) clockwise around the longitudinal axis.

[0020] This allows for precise and stable adjustment of the desired bend. Additional deterioration in beam quality, which can occur when changing the bending direction, can be avoided.

[0021] According to a further development of the system, the rotating device can be designed such that the fiber extends (or winds) counterclockwise around the longitudinal axis.

[0022] This allows for precise and stable adjustment of the desired bend. Additional deterioration in beam quality, which can occur when changing the bending direction, can be avoided. According to a further development of the system, the rotating device can include a first guide. The first guide can be designed as a tube, in particular a Teflon tube. The fiber can be arranged within the first guide. The first guide can extend helically, at least in sections, along the longitudinal axis. The fiber can be arranged to move freely (i.e., not fixed) within the first guide, particularly along the longitudinal axis. The first guide can define the position of the fiber and / or serve to stabilize its position.

[0023] This allows for uniform guidance of the helical section of the fiber. The stress exerted on the fiber by bending can be distributed evenly across the helical section, thus reliably controlling the homogenization rate and the beam quality, particularly the deterioration of the SPP.

[0024] According to a further development of the system, the rotating device can comprise a rod extending along the longitudinal axis. The fiber can extend helically around the rod, at least in sections. The first guide can also extend helically around the rod, at least in sections.

[0025] This allows for uniform guidance of the helical section of the fiber. The stress exerted on the fiber by bending can be distributed evenly across the helical section, thus reliably controlling the degree of homogenization and the degree of beam quality, particularly the deterioration of the SPP (Specific Beam Power). According to a further development of the system, the rotating device can include a second guide. The second guide can be designed as a tube. The fiber can be arranged helically within the second guide. The second guide can extend (straight) along the longitudinal axis. The fiber within the second guide can be arranged to be freely movable (i.e., not fixed), particularly along the longitudinal axis.The pitch of the helical section of the fiber can be adjusted by compressing and / or stretching the fiber within the second guide.

[0026] In particular, the radius can be kept constant using the second guide.

[0027] This allows for uniform guidance of the helical section of the fiber. The stress exerted on the fiber by bending can be distributed evenly across the helical section, thus reliably controlling the degree of homogenization and the degree of beam quality, in particular the deterioration of the SPP.

[0028] According to a further development of the system, the rotary device can comprise at least one support device. The rotary device can comprise two or three support devices, and the support device can have a fiber receptacle. The fiber receptacle can be configured to receive at least a section of the fiber. The support device can be displaceable (or movable) along the longitudinal axis and fixed (or lockable) in at least two different positions along the longitudinal axis. Alternatively or additionally, the support device can be rotatable about the longitudinal axis and fixed in at least two different rotational positions about the longitudinal axis.

[0029] This allows a desired bend to be set using simple means.

[0030] According to a further development of the system, the fiber receptacle can be designed as a through-opening. The fiber can extend through the through-opening. The fiber can be freely movable within the through-opening. It is also conceivable that the fiber can be fixed in the through-opening, for example, by gluing, clamping, and / or welding.

[0031] This allows the fiber to be easily incorporated into the support structure.

[0032] According to a further development of the system, the fiber can be configured as a step-index fiber. Specifically, a fiber can be used whose numerical aperture is not fully utilized by the guided laser radiation. The fiber can have a core diameter of a few pm to 1000 pm (micrometers). The fiber can have a cladding diameter of a few hundred pm to 1500 pm. The fiber can have a numerical aperture of at most 0.25. The fiber can be configured as a passive fiber—also called a transport fiber—that is, without a laser-active material. In other words, the fiber can be configured without doping with a laser-active material.

[0033] According to a further development of the system, the fiber can be fixed in position (arranged) section by section within the rotating device by means of gluing, clamping, and / or welding. For example, one end of the helical section of the fiber can be fixed in place, and a second end of the helical section can be rotated until the desired homogenization is achieved. Once the desired homogenization is achieved, the second end of the helical section of the fiber can also be fixed.

[0034] This allows the desired bend to be achieved using simple means.

[0035] According to a further development of the system, the system can include a laser source for generating the laser beam. The laser source can be configured to generate a laser beam for whose wavelength the fiber functions at least partially or in certain regions as a multi-mode fiber.

[0036] This allows a laser beam to be provided using simple means.

[0037] The above problem is solved by a method for homogenizing a beam profile and / or for adjusting the beam quality of a laser beam with the features of the dependent claim. The method comprises the following steps:

[0038] Providing a fiber for guiding the laser beam, wherein the fiber is configured as a multi-mode fiber, at least section by section. At least section by section by helical arrangement, in particular by guiding, the fiber along a longitudinal axis.

[0039] Varying (or adjusting) the pitch, radius and / or pitch of the helical section of the fiber to homogenize the beam profile and / or adjust the beam quality, in particular to reduce the deterioration of the beam parameter product.

[0040] After varying (or adjusting) the pitch, radius and / or thread height, the fiber or the helical section of the fiber can be fixed or locked in the desired helical shape.

[0041] This allows the beam profile of a laser beam to be adjusted simply, stably and cost-effectively.

[0042] The bending generated in the helical section exerts stress on the fiber. At large bending radii (i.e., with a smaller bend or fewer windings / turns), this stress homogenizes the beam profile. At small bending radii (i.e., with a tighter bend or more windings / turns), the stress increases the internal propagation angle in the fiber core, thus increasing or degrading the resulting beam parameter product (SPP). A desired homogenization can be achieved or adjusted by precisely controlling the bending and thus the SPP, particularly by degrading the SPP. In this context, homogenization refers to smoothing the beam profile of the laser beam. For example,A Gaussian beam profile can be homogenized to a desired top-hat beam profile by selectively degrading the SPP. Homogenization of the beam profile can, in particular, mean that the intensity distribution at the focus is uniform, e.g., top-hat shaped.

[0043] According to a further development of the procedure, the procedure can include the following step:

[0044] Guiding the fiber, keeping the slope or radius of the helical section of the fiber constant.

[0045] This allows a stable bend to be achieved across the entire helical section of the fiber using simple means.

[0046] According to a further development of the procedure, the procedure can include the following step:

[0047] Fixed fixation of a section of fiber in place by means of gluing, clamping and / or welding.

[0048] The procedure may include the following step:

[0049] Twisting a section of the fiber around its longitudinal axis.

[0050] This allows the helical arrangement of the fiber to be implemented using simple means. According to a further development of the method, a rotary device as described above can be used to carry out the process.

[0051] Regarding the advantages achievable with this procedure, reference is made to the relevant explanations of the system. The measures described in connection with the system and / or those explained below can serve to further develop the procedure.

[0052] Further features, details and advantages of the invention will become apparent from the wording of the claims and from the following description of exemplary embodiments with reference to the drawings. The drawings schematically show:

[0053] Fig. 1 a system for homogenizing a beam profile and / or for adjusting the beam quality of a laser beam;

[0054] Fig. 2 shows three side views of a rotary device of the system according to Figure 1 according to a first embodiment;

[0055] Fig. 3 shows a perspective sectional view of the rotary device of the system according to Figure 1 according to a second embodiment and

[0056] Fig. 4 shows a perspective view of the rotary device of the system according to Figure 1, according to a third embodiment. In the following description and in the figures, corresponding components and elements bear the same reference symbols. For the sake of clarity, not all reference symbols are shown in all figures.

[0057] Figure 1 shows a system 11 for homogenizing a beam profile and / or for adjusting the beam quality of a laser beam 12. The system 11 can include a laser source 34 for generating the laser beam 12.

[0058] System 11 includes a fiber 14 for guiding the laser beam 12. The fiber 14 is designed, at least section by section, as a multi-mode fiber for the laser beam 12 (or its wavelength).

[0059] System 11 comprises a rotary device 10 for generating at least one bend along the fiber 14. The fiber 14 is arranged helically, at least in sections, within the rotary device 10 along a longitudinal axis 16. The rotary device 10 is configured to vary or adjust the pitch, radius, and / or thread pitch of the helical section of the fiber.

[0060] Fiber 14 can extend clockwise or counterclockwise around its longitudinal axis. Fiber 14 can be configured as a step-index fiber. Fiber 14 can be configured without a laser-active material.

[0061] The fiber 14 can be fixed in place section by section within the rotary device 10 by means of gluing, clamping and / or welding. It is also conceivable that the fiber 14 can be arranged to be freely movable within the rotary device 10, at least along the longitudinal axis 16.

[0062] Figure 2 shows three side views of the rotary device 10 of the system 11 according to Figure 1 according to a first embodiment.

[0063] In the present case, fiber 14 extends clockwise around the longitudinal axis 16.

[0064] The rotary device 10 can comprise a first guide 18. The first guide 18 can be designed as a tube 20, in particular a Teflon tube. The fiber 14 can be arranged within the first guide 18. The first guide 18 can extend helically, at least in sections, along the longitudinal axis 16.

[0065] The rotating device 10 can comprise a rod 22 extending along the longitudinal axis 16. The fiber 14 can extend helically along the rod 22, at least in sections.

[0066] In the present case, the first guide 18 (hose 20) with the fiber 14 guided therein extends at least sectionally in a helical fashion along the rod 22 (and thus along the longitudinal axis 16).

[0067] The rotating device 10 comprises a first end 36 and a second end 38. These can be rotated relative to each other about the longitudinal axis 16. The first guide 18 is fixedly connected to both the first end 36 and the second end 38. By rotating the two ends 36 and 38, the number of windings of the first guide 18, and thus the number of windings of the fiber 14 arranged within the first guide 18, can be adjusted.

[0068] Figure 2 above shows the rotary device 10 with the first guide 18 and the fiber 14 arranged therein, which has 0.5 turns.

[0069] Figure 2 in the center shows the rotary device 10 with the first guide 18 and the fiber 14 arranged therein, which has 1, 5 windings.

[0070] Figure 2 below shows the rotary device 10 with the first guide 18 and the fiber 14 arranged therein, which has 2, 5 windings.

[0071] In this case, the fiber 14 is arranged to be freely movable within the first guide 18 along the longitudinal axis 16.

[0072] In particular, fiber 14 is not fixed within the first guide 18.

[0073] Figure 3 shows a perspective sectional view of the rotary device 10 of the system 11 according to Figure 1, according to a second embodiment. The second embodiment differs from the first embodiment shown in Figure 2 in the following ways:

[0074] The rotary device 10 can include a second guide 24.

[0075] The second guide 24 can be designed as a (dimensionally stable) tube 26. The fiber 14 can be arranged helically within the second guide 24. The second guide can extend along the longitudinal axis 16.

[0076] Due to the second guide 24, the radius of the helical section of the fiber 14 can be kept constant. By compressing and / or stretching the fiber 14, the pitch of the helical section of the fiber 14 can be varied or adjusted.

[0077] In this case, fiber 14 is designed to be freely movable along the longitudinal axis 16. In particular, fiber 14 is not fixed within the second guide 24.

[0078] Figure 4 shows a perspective view of the rotary device 10 of the system 11 according to Figure 1, according to a third embodiment. The third embodiment differs from the first embodiment shown in Figure 2 in the following ways:

[0079] The rotary device 10 can comprise at least one support device 28. The support device 28 can comprise a fiber receptacle 30. The fiber receptacle 30 can be configured to receive at least one section of the fiber 14.

[0080] The fiber receptacle 30 can be configured as a through-opening 32. The fiber 14 can extend through the through-opening 32. The fiber 14 can be arranged to be freely movable along the longitudinal axis 16 within the through-opening 32. It is also conceivable that the fiber 14 can be fixed in the through-opening 32, for example, by gluing, clamping, and / or welding. The support device 28 can be designed to be displaceable along the longitudinal axis 16 (indicated in Figure 4 by means of a straight double arrow) and to be fixable in at least two different positions.

[0081] Alternatively or additionally, the support device 28 can be rotatable about the longitudinal axis 16 (indicated in Figure 4 by means of a curved double arrow) and fixed in at least two different rotational positions.

[0082] The support device 28 comprises a fixing opening 40. The support device 28 can be connected, for example, to a rod (not shown) via the fixing opening 40 (see the above descriptions of the first embodiment). The rod (not shown) can extend through the fixing opening 40 and along the longitudinal axis 16.

[0083] The support device 28 comprises three support devices 28, each spaced apart from the others along the longitudinal axis 16j. The three support devices 28 are arranged in different rotational positions. The support device 28 on the left in Figure 4 is arranged in a first rotational position. The support device 28 in the middle of Figure 4 is arranged in a second rotational position, rotated 90° relative to the first rotational position. The support device 28 on the right in Figure 4 is arranged in a third rotational position, rotated 180° relative to the second rotational position.

[0084] In this case, the fiber 14 is designed to be freely movable along the longitudinal axis 16. In particular, the fiber 14 is not fixed within the support structures 28. The following describes a method for homogenizing a beam profile and / or adjusting the beam quality of a laser beam 12 with reference to Figures 1 to 4. The method comprises the following steps:

[0085] Providing a fiber 14 for guiding the laser beam 12, wherein the fiber 14 is designed at least section by section as a multi-mode fiber for the laser beam 12 (or its wavelength).

[0086] At least sectionally helical arrangement, in particular guiding, of the fiber 14 along a longitudinal axis 16 .

[0087] Varying the slope, radius and / or pitch of the helical section of fiber 14 to homogenize the beam profile and / or adjust the beam quality, in particular to reduce the beam parameter product.

[0088] After varying the pitch, radius and / or pitch, the helical section can be fixed in the desired helical shape.

[0089] The procedure may include the following step:

[0090] Guiding the fiber 14, whereby the slope or radius of the helical section of the fiber 14 is kept constant.

[0091] The procedure may include the step: fixing a section of fiber 14 in place by gluing, clamping and / or welding.

[0092] To carry out the method, a rotary device 10 as described above can be used. In particular, the rotary device 10 can be the rotary device 10 shown in Figures 1 to 4.

Claims

Patent claims 1. System (11) for homogenizing a beam profile and / or for adjusting a beam quality of a laser beam (12) comprising a fiber (14) for guiding the laser beam (12), wherein the fiber (14) is configured at least section by section as a multi-mode fiber for the laser beam (12), and a rotary device (10) for generating at least one bend along the fiber (14) , wherein the fiber (14) is arranged at least sectionally helically along a longitudinal axis (16) within the rotary device (10), wherein the rotary device (10) is configured to vary a pitch, radius and / or pitch of the helical section of the fiber (14 .

2. System (11) according to claim 1, characterized in that the rotary device (10) is designed such that the fiber (14) extends clockwise around the longitudinal axis (16).

3. System (11) according to claim 1, characterized in that the rotary device (10) is arranged such that the fiber (14) extends counterclockwise around the longitudinal axis (16).

4. System (11) according to one of the preceding claims, characterized in that the rotary device (10) comprises a first guide (18), in particular a tube (20), wherein the fiber (14) is arranged within the first guide (18), wherein the first guide (18) extends at least in sections in a helical shape along the longitudinal axis (16).

5. System (11) according to one of the preceding claims, characterized in that the rotary device (10) comprises a rod (22) extending along the longitudinal axis (16), wherein the fiber (14) extends at least partially in a helical manner along the rod (22).

6. System (11) according to one of the preceding claims, characterized in that the rotary device (10) comprises a second guide (24), in particular a tube (26), wherein the fiber (14) is arranged helically within the second guide (24), wherein the second guide (24) extends along the longitudinal axis (16).

7. System (11) according to one of the preceding claims, characterized in that the rotary device (10) comprises at least one support device (28), in particular two or three support devices (28), wherein the support device (28) comprises a fiber receptacle (30) for receiving at least one section of the fiber (14), wherein the support device (28) is designed to be displaceable along the longitudinal axis (16) and fixable at least in two different positions and / or rotatable about the longitudinal axis (16) and fixable in at least two different rotational positions.

8. System (11) according to the preceding claim, characterized in that the fiber receptacle (30) is designed as a through-opening (32), wherein the fiber (14) extends through the through-opening (32).

9. System (11) according to one of the preceding claims, characterized in that the fiber (14) is designed as a step-index fiber.

10. System (11) according to one of the preceding claims, characterized in that the fiber (14) is arranged section by section in the rotary device (10) in a fixed position by means of gluing, clamping and / or welding.

11. System (11) according to one of the preceding claims, characterized in that the system (11) comprises a laser source (34) for generating the laser beam (12).

12. Method for homogenizing a beam profile and / or adjusting the beam quality of a laser beam (12) comprising the steps: Providing a fiber (14) for guiding the laser beam (12) wherein the fiber (14) is designed at least section by section as a multi-mode fiber for the laser beam (12); At least section by section helical arrangement, in particular guiding, of the fiber (14) along a longitudinal axis (16) ; Varying the pitch, radius and / or pitch of the helical section of the fiber (14) to homogenize the beam profile and / or adjust the beam quality, in particular to reduce the deterioration of the beam parameter product.

13. Method according to claim 12, characterized by the step: Guiding the fiber (14) , wherein the slope or radius of the helical section of the fiber (14) is kept constant.

14. Method according to claim 12 or 13, characterized by the step: Fixed fixation of a section of the fiber (14) by means of gluing, clamping and / or welding.

15. Method according to claims 12 to 14, characterized in that a rotary device (10) according to one of claims 1 to 14 is used to carry out the method. 11 is used.

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