Beam mode changing apparatus and beam mode changing method

Abstract

To provide a beam mode changing device capable of changing a beam mode.SOLUTION: The first and second collimator lenses 105 and 106 are movable in a direction perpendicular to the first and second optical axes, respectively. When the first and second collimator lenses 105 and 106 are at the reference positions, the optical element (dichroic mirror 111) causes the first and second laser beams to enter the focusing lens 112 in a state where the optical axes of the first and second laser beams coincide with each other. The focusing lens 112 focuses the first and second laser beams to be incident on the center of the core of the process fiber 12. The first and second driving units 107 and 109 move the first and second collimator lenses 105 and 106 independently of each other so as to change the distance from the center of the core to the position at which the focusing lens 112 focuses the first and second laser beams and causes the first and second laser beams to enter the core.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a beam mode changing device and a beam mode changing method. [Background technology]

[0002] Patent Document 1 describes the following beam mode changing device. A bend mirror transmits the first laser beam and reflects the second laser beam out of first and second laser beams, which are collimated lights with different wavelengths. A focusing lens focuses the first and second laser beams and makes them incident on the input end of a process fiber. The beam mode changing device described in Patent Document 1 changes the beam mode by rotating the bend mirror to change the angles of incidence of the first and second laser beams onto the process fiber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-199513 Summary of the Invention [Problem to be solved by the invention]

[0004] In a conventional beam mode change device, when the angle of the bend mirror is changed, a beam shift occurs in which the direction of travel of the first laser beam passing through the bend mirror changes. In a conventional beam mode change device, the distances from the center of the core of the process fiber to the positions where the first and second laser beams enter the core cannot be changed independently for the first laser beam and the second laser beam.

[0005] There is a need for a beam mode changing device and a beam mode changing method that can change the beam mode by independently changing the distance from the center of the core of the process fiber at which the first laser beam and the second laser beam are incident on the core without being affected by each other. [Means for solving the problem]

[0006] A first aspect of one or more embodiments includes a first collimating lens that is movable in a direction perpendicular to a first optical axis and converts a first laser beam of divergent light having a first wavelength and traveling on the first optical axis into collimated light; a second collimating lens that is movable in a direction perpendicular to a second optical axis different from the first optical axis and converts a second laser beam of divergent light having a second wavelength different from the first wavelength into collimated light; a first driving unit that moves the first collimating lens in a direction perpendicular to the first optical axis; a second driving unit that moves the second collimating lens in a direction perpendicular to the second optical axis; and a reflecting lens that transmits the first laser beam converted into collimated light and reflects the second laser beam converted into collimated light. and a focusing lens that focuses the first and second laser beams emitted from the optical element and makes them incident on a core of a process fiber, wherein when the first and second collimating lenses are at a reference position, the optical element makes the first laser beam and the second laser beam incident on the focusing lens with their optical axes aligned, and when the first and second collimating lenses are at the reference position, the focusing lens makes the first and second laser beams incident on the center of the core, and the first and second driving units move the first and second collimating lenses independently of each other so as to change the distances from the center of the core to the positions at which the focusing lens focuses the first and second laser beams and makes them incident on the core.

[0007] A second aspect of one or more embodiments is a method for converting a first laser beam of divergent light having a first wavelength and traveling on a first optical axis into collimated light by a first collimating lens movable in a direction perpendicular to a first optical axis, and a second laser beam of divergent light having a second wavelength different from the first wavelength and traveling on a second optical axis into collimated light by a second collimating lens movable in a direction perpendicular to a second optical axis different from the first optical axis, and when the first and second collimating lenses are at reference positions, the first laser beam converted into collimated light is transmitted through an optical element and the second laser beam converted into collimated light is reflected by the optical element, thereby aligning the optical axes of the first laser beam and the second laser beam, and and a collimating lens is disposed at a reference position, the first and second laser beams having their optical axes aligned are focused by a focusing lens and incident on the center of a core of a process fiber, thereby setting the first and second laser beams transmitted through the process fiber to a first beam mode, and the first and second collimating lenses are moved independently of each other to change at least one of the distance from the center of the core to a position where the focusing lens focuses the first laser beam and incident it on the core and the distance from the center of the core to a position where the focusing lens focuses the second laser beam and incident it on the core, thereby setting the first and second laser beams transmitted through the process fiber to a beam mode different from the first beam mode. [Effects of the Invention]

[0008] According to one or more embodiments of the beam mode changing device and beam mode changing method, the distances from the center of the core of the process fiber at which the first laser beam and the second laser beam are incident on the core can be changed independently without being affected by each other, thereby changing the beam mode. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of a laser processing machine equipped with a beam mode changing device according to one or more embodiments. [Figure 2] FIG. 2 is a diagram illustrating a reference state in which the first and second collimating lenses are in reference positions in the beam mode changing device according to one or more embodiments. [Figure 3] FIG. 3 is a diagram illustrating a state in which only the second collimator lens is moved in the beam mode changing device according to one or more embodiments. [Figure 4] FIG. 4 is a diagram illustrating a first example of a state in which the first and second collimator lenses are moved in the beam mode changing device according to one or more embodiments. [Figure 5] FIG. 5 is a diagram illustrating a second example of a state in which the first and second collimator lenses are moved in the beam mode changing device according to one or more embodiments. [Figure 6A] FIG. 6A is a cross-sectional view showing the first beam mode in the reference state shown in FIG. 2, taken along a plane perpendicular to the traveling direction of the laser beam. [Figure 6B] FIG. 6B is a cross-sectional view showing the second beam mode in the state shown in FIG. 3, taken along a plane perpendicular to the traveling direction of the laser beam. [Figure 6C] FIG. 6C is a cross-sectional view showing the third beam mode in the state shown in FIG. 4, taken along a plane perpendicular to the traveling direction of the laser beam. [Figure 6D] FIG. 6D is a cross-sectional view showing the fourth beam mode in the state shown in FIG. 5, taken along a plane perpendicular to the traveling direction of the laser beam. [Figure 7A] FIG. 7A is a cross-sectional view showing the first beam mode in the reference state shown in FIG. 2, taken along a plane parallel to the propagation direction of the laser beam. [Figure 7B] FIG. 7B is a cross-sectional view showing the second beam mode in the state shown in FIG. 3, taken along a plane parallel to the traveling direction of the laser beam. [Figure 7C] FIG. 7C is a cross-sectional view showing the third beam mode in the state shown in FIG. 4, taken along a plane parallel to the traveling direction of the laser beam. [Figure 7D] FIG. 7D is a cross-sectional view showing the fourth beam mode in the state shown in FIG. 5, taken along a plane parallel to the traveling direction of the laser beam. DETAILED DESCRIPTION OF THE INVENTION

[0010] A beam mode changing device and a beam mode changing method according to one or more embodiments will be specifically described below with reference to the accompanying drawings. In Fig. 1, a laser processing machine 100 includes a beam mode changing device 10 according to one or more embodiments, a laser processing unit 20, and a process fiber 12 that transmits a laser beam emitted from the beam mode changing device 10 to the laser processing unit 20. The process fiber 12 is installed along cable ducts (not shown) on the X and Y axes arranged in the laser processing unit 20. The specific configuration and operation of the beam mode changing device 10 will be described in detail later.

[0011] The laser processing unit 20 has a processing table 21 on which the sheet metal W, which is the workpiece to be processed, is placed, a gate-shaped X-axis carriage 22, a Y-axis carriage 23, and a collimator unit 30 fixed to the Y-axis carriage 23. The X-axis carriage 22 is configured to be movable in the X-axis direction on the processing table 21. The Y-axis carriage 23 is configured to be movable in the Y-axis direction perpendicular to the X-axis on the X-axis carriage 22. The X-axis carriage 22 and the Y-axis carriage 23 function as a movement mechanism that moves a processing head 34, which will be described later, along the surface of the sheet metal W in the X-axis direction, Y-axis direction, or any combined direction of the X-axis and Y-axis directions.

[0012] Instead of moving the processing head 34 along the surface of the metal sheet W, the processing head 34 may be configured to be fixed in position and the metal sheet W may move. The laser processing unit 20 may be provided with a movement mechanism that moves the processing head 34 relative to the surface of the metal sheet W.

[0013] The collimator unit 30 has a collimator lens 31, a bend mirror 32, a focusing lens 33, and a processing head 34. The collimator lens 31 converts the diverging laser beam emitted from the exit end of the process fiber 12 into collimated light. The bend mirror 32 reflects the collimated laser beam LB emitted from the collimator lens 31 downward in the Z-axis direction, which is perpendicular to the X-axis and Y-axis. The focusing lens 33 is disposed in the processing head 34. The focusing lens 33 focuses the laser beam LB reflected by the bend mirror 32 and irradiates the metal sheet W.

[0014] The laser processing unit 20 configured as described above processes the metal sheet W by moving the position where the laser beam LB emitted from the processing head 34 is irradiated onto the metal sheet W in the X-axis direction and the Y-axis direction. Typically, the processing of the metal sheet W is cutting of the metal sheet W. The processing of the metal sheet W is not limited to cutting of the metal sheet W, but may also be marking of the metal sheet W or welding of two metal sheets W. When cutting the metal sheet W, an assist gas is sprayed onto the metal sheet W to remove molten material. In FIG. 1, the configuration for spraying the assist gas is not shown.

[0015] 2 to 5, a specific configuration of the beam mode changing device 10 and a beam mode changing method by the beam mode changing device 10 will be described. The beam mode changing device 10 selects an appropriate beam mode depending on the thickness or material of the metal plate W.

[0016] 2, the beam mode changing device 10 includes laser oscillators 101 and 102, feeding fibers 103 and 104, collimating lenses 105 and 106, driving units 107 and 109, moving mechanisms 108 and 110, a dichroic mirror 111, a focusing lens 112, and a control device 113. The laser oscillator 101 is a first laser oscillator, and the laser oscillator 102 is a second laser oscillator. The collimating lens 105 is a first collimating lens, and the collimating lens 106 is a second collimating lens.

[0017] As an example, the laser oscillator 101 generates and emits a laser beam with a wavelength of 1080 nm (first wavelength), and the laser oscillator 102 generates and emits a laser beam with a wavelength of 1050 nm (second wavelength). The laser oscillators 101 and 102 can be configured with known fiber laser oscillators. The fiber laser oscillator includes multiple laser diode devices, a combiner, an active fiber, a high-reflection fiber Bragg grating, and a low-reflection fiber Bragg grating. The fiber Bragg grating is abbreviated as FBG.

[0018] The combiner optically combines laser beams emitted from multiple laser diode devices. The core of the active fiber is doped with a rare earth element. The active fiber is disposed between a high-reflection FBG and a low-reflection FBG. The laser beam emitted from the active fiber repeatedly travels back and forth between the high-reflection FBG and the low-reflection FBG, and a laser beam of a predetermined wavelength is emitted from the low-reflection FBG. The wavelengths of the laser beams emitted by the laser oscillators 101 and 102 can be determined by setting the wavelengths reflected by the high-reflection FBG and the low-reflection FBG to specific wavelengths.

[0019] A laser beam with a wavelength of 1080 nm emitted from laser oscillator 101 is incident on and transmitted through feeding fiber 103. Feeding fiber 103 emits a diverging laser beam indicated by a dashed line from its exit end. The laser beam indicated by the dashed line will be referred to as the first laser beam. The first laser beam travels on a first optical axis. A laser beam with a wavelength of 1050 nm emitted from laser oscillator 102 is incident on and transmitted through feeding fiber 104. Feeding fiber 104 emits a diverging laser beam indicated by a dashed line from its exit end. The laser beam indicated by the dashed line will be referred to as the second laser beam. The second laser beam travels on a second optical axis different from the first optical axis.

[0020] The laser oscillators 101 and 102 can also be provided outside the beam mode changing device 10. If the laser oscillators 101 and 102 are provided inside the beam mode changing device 10, the beam mode changing device 10 becomes a laser oscillator with a beam mode changing function. If a laser oscillator having only one laser oscillator is replaced with the beam mode changing device 10, which is a laser oscillator with a beam mode changing function, the laser processing machine 100 can select an appropriate beam mode from a plurality of beam modes to process the sheet metal W.

[0021] It is preferable to use fiber laser oscillators as the laser oscillators 101 and 102. If the laser oscillators 101 and 102 are fiber laser oscillators, the first and second laser beams can have wavelengths in the 1 μm band that are close to each other. The difference between the first wavelength and the second wavelength needs to be at least 5 nm. However, the laser oscillators 101 and 102 are not limited to being fiber laser oscillators. The laser oscillator 101 may be a fiber laser oscillator that emits a laser beam with a wavelength of 1060 nm to 1080 nm, and the laser oscillator 102 may be a direct diode laser (DDL) oscillator that emits a laser beam with a wavelength of 910 nm to 950 nm.

[0022] The collimating lens 105 converts the first laser beam emitted from the exit end of the feeding fiber 103 into collimated light and emits the collimated light. The collimating lens 106 converts the second laser beam emitted from the exit end of the feeding fiber 104 into collimated light and emits the collimated light. The collimating lens 105 is configured to be movable in a direction perpendicular to the first optical axis by a moving mechanism 108. The collimating lens 106 is configured to be movable in a direction perpendicular to the second optical axis by a moving mechanism 110.

[0023] The movement mechanisms 108 and 110 can be configured with, for example, any one of a gear, a belt, a rack and pinion, a worm gear, a ball screw, a rail, etc., or any combination of these. The movement mechanisms 108 and 110 are not limited in configuration as long as they can move the collimator lenses 105 and 106, respectively.

[0024] The driving units 107 and 109 can drive the moving mechanisms 108 and 110 to move the collimating lenses 105 and 106, respectively, under the control of the control unit 113. The driving unit 107 is a first driving unit, and the driving unit 109 is a second driving unit. The driving units 107 and 109 can be configured, for example, by motors. The control unit 113 can be configured by a PLC (Programmable Logic Controller). The control unit 113 controls the driving units 107 and 109 under the control of an NC device (not shown) that controls the overall movement of the laser processing machine 100. Instead of the control unit 113, the NC device may directly control the driving units 107 and 109.

[0025] The control device that controls the driving units 107 and 109 may be a control device 113 provided inside the beam mode changing device 10, or may be a control device such as an NC device provided outside the beam mode changing device 10. If the control device 113 is provided inside the beam mode changing device 10, the NC device may supply a command to the control device 113 to select a beam mode, which will be described later. In response to the command from the NC device, the control device 113 may control one or both of the driving units 107 and 109 to move one or both of the collimating lens 105 and the collimating lens 106 in accordance with the selected beam mode.

[0026] FIG. 2 shows the reference state of the beam mode change device 10, in which the collimating lenses 105 and 106 are not moved and are at their reference positions. When the beam mode change device 10 is in the reference state, the centers (core centers) of the exit ends of the feeding fibers 103 and 104 coincide with the centers of the collimating lenses 105 and 106, respectively. A dielectric multilayer film that transmits a laser beam with a wavelength of 1080 nm and reflects a laser beam with a wavelength of 1050 nm is formed on the surface of the dichroic mirror 111 facing the focusing lens 112. The dichroic mirror 111 is disposed at a predetermined angle with respect to the first optical axis of the first laser beam emitted from the collimating lens 105, and its position is fixed. The predetermined angle may be 45 degrees or another angle.

[0027] The first laser beam emitted from the collimator lens 105 passes through the dichroic mirror 111. The second laser beam is reflected by the surface of the dichroic mirror 111 facing the focusing lens 112, and its traveling direction is bent. As a result, the first laser beam indicated by the dashed line and the second laser beam indicated by the broken line are incident on the focusing lens 112 with their optical axes aligned. At this time, the optical axes of the first and second laser beams are aligned with the center of the focusing lens 112.

[0028] The dichroic mirror 111 is an example of an optical element that transmits the first laser beam converted into collimated light and reflects the second laser beam converted into collimated light. Other optical elements such as a VBG (Volume Gragg Grating) may be used instead of the dichroic mirror 111. Use of the dichroic mirror 111 allows the beam mode changing device 10 to be configured compactly.

[0029] The focusing lens 112 focuses the first and second laser beams and makes them incident on the incident end of the process fiber 12. At this time, the first and second laser beams are incident on the center of the core of the process fiber 12. The process fiber 12 has a configuration in which graded-index fibers (hereinafter, GI fibers) 12G are fused to both ends of a step-index fiber (hereinafter, SI fiber) 12S. The first and second laser beams incident on the incident end of the process fiber 12 propagate through the GI fiber 12G, the SI fiber 12S, and the GI fiber 12G, and are emitted from the exit end of the process fiber 12 and incident on the collimator unit 30. In Figures 2 to 5, the diameter of the process fiber 12 is exaggerated. The operation of the laser processing unit 20 including the collimator unit 30 is as described above.

[0030] The configuration of the process fiber 12 is not limited to the configuration in which the SI fiber 12S is sandwiched between the GI fibers 12G.

[0031] When the beam mode changing device 10 is in the reference state shown in FIG. 2, the beam mode of the laser beam LB irradiated onto the metal sheet W is the first beam mode of a steep Gaussian beam shown in FIGS. 6A and 7A. The beam mode is also called a beam profile. The beam mode (beam profile) indicates the intensity distribution when the laser beam is viewed in cross section, and is a characteristic that indicates the relationship between the distance from the center of the laser beam and the beam intensity. The beam profile shown by the solid line in FIG. 7A indicates the beam profile of both the first laser beam and the second laser beam.

[0032] 6A to 6D show the beam profile in cross-sectional views when the laser beam LB is cut along a plane perpendicular to the direction of travel. FIGS. 7A to 7D show the beam profile in cross-sectional views when the laser beam LB is cut along a plane parallel to the direction of travel. In FIGS. 7A to 7D, the horizontal axis represents the position in the plane perpendicular to the direction of travel of the laser beam LB, and the vertical axis represents the beam intensity. FIGS. 6A to 6D and 7A to 7D show the beam profile on the surface of the metal sheet W.

[0033] The first beam mode shown in FIGS. 6A and 7A is suitable for cutting a metal sheet W having a thickness of 1 mm to 5 mm without oxidation.

[0034] Figure 3 shows a state in which the control device 113 controls the drive unit 109 to move only the collimator lens 106 to the right in Figure 3. Because the position of the collimator lens 105 is the same as in Figure 2, the first laser beam passes through the dichroic mirror 111, is focused by the focusing lens 112, and is incident on the center of the core of the process fiber 12. Because the collimator lens 106 has moved to the right in Figure 3, the second optical axis of the second laser beam, indicated by the dashed line, deviates from the center of the collimator lens 106.

[0035] As a result, the second optical axis of the second laser beam emitted from collimator lens 106 is tilted compared to the second optical axis when collimator lens 106 is not moved. Then, the second laser beam is reflected by the surface of dichroic mirror 111 facing focusing lens 112 at an angle different from the angle when collimator lens 106 is not moved. As a result, the second laser beam reflected by dichroic mirror 111 enters focusing lens 112 with its optical axis deviated from the center of focusing lens 112.

[0036] Therefore, while the first laser beam is incident on the center of the core of the process fiber 12, the second laser beam is incident on a position offset a predetermined distance from the center of the core of the process fiber 12. That is, the position of incidence of the second laser beam on the core changes compared to that in the first beam mode. When the beam mode changing device 10 is in the state shown in FIG. 3, the beam mode of the laser beam LB irradiated onto the metal sheet W becomes the second beam mode shown in FIGS. 6B and 7B, in which a smooth beam due to the second laser beam exists around a Gaussian beam due to the first laser beam. The second beam mode is different from the first beam mode.

[0037] In the beam profile shown by the solid line in FIG. 7B, the Gaussian beam located in the center is the beam profile due to the first laser beam, and the smooth beam located on the periphery is the beam profile due to the second laser beam.

[0038] The second beam mode shown in FIGS. 6B and 7B is suitable for cutting the metal sheet W having a thickness of 6 mm to 15 mm without oxidation.

[0039] 3, the collimator lens 106 may be set to a reference position, and the control device 113 may control the drive unit 109 to move only the collimator lens 105 downward in FIG. 3. In this case, the beam mode of the laser beam LB irradiated onto the metal sheet W is a beam mode in which a smooth beam due to the first laser beam exists around a Gaussian beam due to the second laser beam.

[0040] FIG. 4 shows a first example of a state in which the control device 113 controls the drivers 107 and 109 to move the collimator lens 105 downward in FIG. 4 and the collimator lens 106 rightward in FIG. 4. Because the collimator lens 105 has moved downward in FIG. 4, the first optical axis of the first laser beam is tilted compared to the first optical axis when the collimator lens 105 is not moved, and deviates from the center of the collimator lens 105. As a result, the first laser beam passes through the dichroic mirror 111 at an angle different from the angle when the collimator lens 105 is not moved. As a result, the first laser beam that has passed through the dichroic mirror 111 enters the focusing lens 112 with its optical axis deviated from the center of the focusing lens 112.

[0041] As in Figure 3, the second laser beam is reflected by the surface of dichroic mirror 111 facing focusing lens 112 at an angle different from the angle when collimating lens 106 is not moved, and enters focusing lens 112 with its optical axis offset from the center of focusing lens 112.

[0042] 4 shows a case where the distance from the center of the core to the position where the first laser beam is incident on the core of the process fiber 12 is the same as the distance from the center of the core to the position where the second laser beam is incident on the core of the process fiber 12. That is, in the first example, the control device 113 controls the drivers 107 and 109 to move the collimating lenses 105 and 106 so that the first and second laser beams are incident on positions the same distance from the center of the core of the process fiber 12.

[0043] When the beam mode changing device 10 is in the state shown in Fig. 4, the beam mode of the laser beam LB irradiated onto the metal sheet W becomes the third beam mode of a ring beam shown in Fig. 6C and Fig. 7C. The beam profile shown by the solid line in Fig. 7C indicates the beam profile of both the first laser beam and the second laser beam. The third beam mode is a beam mode different from the first and second beam modes.

[0044] 4, the first and second laser beams are shown as being shifted in the same direction when they are incident on the core of the process fiber 12, but the shifting directions may be different or may be any direction. If the first and second laser beams are incident on the process fiber 12 at positions spaced the same distance from the center of the core, the third beam mode of a ring beam shown in FIGS. 6C and 7C is obtained.

[0045] The third beam mode shown in FIGS. 6C and 7C is suitable for oxygen cutting of a metal sheet W having a thickness of 13 mm to 25 mm.

[0046] 5 shows a second example of a state in which the control device 113 controls the drivers 107 and 109 to move the collimator lens 105 downward in FIG. 4 and the collimator lens 106 rightward in FIG. 4. In the example shown in FIG. 5, the movement amount of the collimator lens 105 is smaller than that in FIG. 4, and the movement amount of the collimator lens 106 is approximately the same as that in FIG. 4.

[0047] The second laser beam is incident on the process fiber 12 at a position offset from the center of the core by the same distance as in FIG. 3. The first laser beam is incident on the process fiber 12 at a position offset from the center of the core by a predetermined distance. The distance by which the first laser beam is offset from the center of the core is shorter than the distance by which the second laser beam is offset from the center of the core. Therefore, the first and second laser beams are incident on positions offset from the center of the core such that the first laser beam is located on the inside and the second laser beam is located on the outside.

[0048] 5 illustrates a case where the distance from the center of the core to the position where the first laser beam is incident on the core of the process fiber 12 is different from the distance from the center of the core to the position where the second laser beam is incident on the core of the process fiber 12. That is, in the second example, the control device 113 controls the drivers 107 and 109 to move the collimating lenses 105 and 106 so that the first and second laser beams are incident on positions that are different distances from the center of the core of the process fiber 12.

[0049] When the beam mode changing device 10 is in the state shown in FIG. 5, the beam mode of the laser beam LB irradiated onto the metal sheet W becomes the fourth beam mode shown in FIGS. 6D and 7D. The fourth beam mode is a beam mode different from the first to third beam modes. In FIG. 7D, the beam profile of the first laser beam is shown by a dashed line, the beam profile of the second laser beam is shown by a broken line, and the solid line shows a beam profile obtained by combining the two. The fourth beam mode corresponds to the first beam mode shown in FIGS. 6A and 7A, with the beam intensity reduced and the beam size widened.

[0050] The fourth beam mode shown in FIG. 6D and FIG. 7D is suitable for cutting the metal sheet W having a thickness of 6 mm to 15 mm without oxidation.

[0051] Incidentally, the operation of the beam mode changing device 10 has been explained using the first to fourth beam modes as examples, but the beam mode changing device 10 can change the beam mode steplessly by adjusting the amount of movement of the collimator lenses 105 and 106.

[0052] 2 to 5, focusing lens 112 may be configured to be movable in a direction perpendicular to the first optical axis by a movement mechanism similar to movement mechanism 108 or 110. A driving unit (not shown) may drive the movement mechanism to move focusing lens 112 in a direction perpendicular to the first optical axis.

[0053] In the beam mode changing device 10 configured as described above, even if the collimating lens 105 is moved to change the incident position of the first laser beam onto the process fiber 12, no beam shift occurs in the second laser beam and no impact is felt on the incident position on the process fiber 12. Furthermore, in the beam mode changing device 10, even if the collimating lens 106 is moved to change the incident position of the second laser beam onto the process fiber 12, no beam shift occurs in the first laser beam and no impact is felt on the incident position on the process fiber 12.

[0054] The beam mode changing device 10 can change the beam mode by independently changing the positions at which the first and second laser beams enter the core of the process fiber 12 for the first laser beam and the second laser beam.

[0055] The present invention is not limited to one or more of the above-described embodiments, and various modifications can be made without departing from the spirit of the present invention. [Explanation of symbols]

[0056] 10 Beam mode change device 12 Process Fiber 20 Laser processing unit 21 Processing table 22 X-axis carriage 23 Y-axis carriage 30 Collimator Unit 31 Collimating lens 32 Bend Mirror 33 Focusing Lens 34 Processing head 100 Laser Processing Machine 101,102 Laser oscillator 103,104 Feeding fiber 105,106 Collimating lens 107,109 Drive unit 108,110 Moving mechanism 111 Dichroic mirror 112 focusing lens W sheet metal

Claims

1. a first collimating lens that is movable in a direction perpendicular to a first optical axis and converts a first laser beam of divergent light having a first wavelength and traveling on the first optical axis into collimated light; a second collimator lens that is movable in a direction perpendicular to a second optical axis different from the first optical axis and converts a second laser beam of divergent light having a second wavelength different from the first wavelength and traveling on the second optical axis into collimated light; a first driving unit that moves the first collimator lens in a direction perpendicular to the first optical axis; a second driving unit that moves the second collimator lens in a direction perpendicular to the second optical axis; an optical element that transmits the first laser beam converted into collimated light and reflects the second laser beam converted into collimated light; a focusing lens that focuses the first and second laser beams emitted from the optical element and makes them incident on a core of a process fiber; Equipped with When the first and second collimating lenses are at reference positions, the optical element causes the first laser beam and the second laser beam to be incident on the focusing lens in a state where their optical axes are aligned, when the first and second collimating lenses are at reference positions, the focusing lens causes the first and second laser beams to be incident on the center of the core; The first and second driving units move the first and second collimating lenses independently of each other so as to change the distance from the center of the core to the position where the focusing lens focuses the first and second laser beams and makes them incident on the core. Beam mode change device.

2. 2. The beam mode changing device according to claim 1, wherein the optical element is a dichroic mirror having a dielectric multilayer formed on the surface facing the focusing lens, the dielectric multilayer transmitting the first laser beam and reflecting the second laser beam.

3. a first laser oscillator that emits a laser beam having the first wavelength; a second laser oscillator that emits a laser beam having the second wavelength; Furthermore, The first and second laser oscillators are fiber laser oscillators.

3. The beam mode changing device according to claim 1 or 2.

4. The beam mode changing device according to claim 1 or 2, further comprising a control device that controls the amount of movement of the first collimating lens by the first driving unit and the amount of movement of the second collimating lens by the second driving unit.

5. converting a first laser beam of divergent light having a first wavelength and traveling on the first optical axis into collimated light by a first collimating lens that is movable in a direction perpendicular to the first optical axis; converting a second laser beam of divergent light having a second wavelength different from the first wavelength and traveling on the second optical axis into collimated light by a second collimating lens that is movable in a direction perpendicular to a second optical axis different from the first optical axis; When the first and second collimating lenses are at a reference position, the first laser beam converted into collimated light is transmitted through an optical element, and the second laser beam converted into collimated light is reflected by the optical element, thereby aligning the optical axes of the first laser beam and the second laser beam; when the first and second collimating lenses are at reference positions, the first and second laser beams, whose optical axes are aligned with each other, are focused by a focusing lens and made incident on the center of a core of a process fiber, thereby making the first and second laser beams transmitted through the process fiber into a first beam mode; The first and second collimating lenses are moved independently of each other so as to change at least one of the distance from the center of the core to a position where the focusing lens focuses the first laser beam and makes it incident on the core and the distance from the center of the core to a position where the focusing lens focuses the second laser beam and makes it incident on the core, thereby making the first and second laser beams transmitted through the process fiber into a beam mode different from the first beam mode. How to change beam mode.

6. 6. The beam mode changing method according to claim 5, wherein the first and second laser beams transmitted through the process fiber are changed to a second beam mode different from the first beam mode by moving only one of the first collimating lens and the second collimating lens so as to change only one of the distance from the center of the core to a position where the focusing lens focuses the first laser beam and makes it incident on the core and the distance from the center of the core to a position where the focusing lens focuses the second laser beam and makes it incident on the core.

7. 6. The beam mode changing method according to claim 5, wherein the first and second collimating lenses are moved so that a distance from the center of the core to a position where the focusing lens focuses the first laser beam and makes it incident on the core is the same as a distance from the center of the core to a position where the focusing lens focuses the second laser beam and makes it incident on the core, thereby changing the first and second laser beams transmitted through the process fiber to a third beam mode different from the first beam mode.

8. 6. The beam mode changing method according to claim 5, wherein the first and second collimating lenses are moved so that a distance from the center of the core to a position where the focusing lens focuses the first laser beam and makes it incident on the core is different from a distance from the center of the core to a position where the focusing lens focuses the second laser beam and makes it incident on the core, thereby changing the first and second laser beams transmitted through the process fiber to a fourth beam mode different from the first beam mode.

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