Numerical aperture variable device, laser device, and laser processing machine

Abstract

The present invention is a numerical aperture variable device that rearranges the spatial distribution or spatial position of a plurality of laser beams (LA, LB) incident from a laser oscillator, condenses the rearranged plurality of laser beams (LA, LB), and enters a transmission fiber, the numerical aperture variable device being provided with light-shielding members (326-1, 326-2), the light-shielding members (326-1, 326-2) being configured so that the light-shielding members (326-1, 326-2) emit light to the transmission fiber. And a plurality of light shields that are provided on an extension line of the optical axis of the transmission fiber and that shield reflected laser light, which is laser light toward the laser oscillator from the transmission fiber.

Description

Technical Field

[0001] The present invention relates to a numerical aperture variable device for changing the incident numerical aperture to a transmission optical fiber, a laser device, and a laser processing machine. Background Art

[0002] A laser processing machine generally includes: a laser oscillator; a focusing lens that focuses the laser light emitted from the laser oscillator; a transmission fiber that transmits the laser light focused by the focusing lens; and a processing head that irradiates the laser light from the transmission fiber to a desired position on the workpiece. In such a laser processing machine, a structure is known in which a plurality of laser lights are emitted to a single transmission fiber in order to achieve high output.

[0003] Patent document 1 discloses a beam parameter adjustment system that changes the spatial distribution of a plurality of beams from a beam source having a polarization state and collectively having a spatial distribution, so that the beams with the changed spatial distribution converge on the end face of a transmission optical fiber. In the technology described in patent document 1, the spatial distribution of the incident beam to the transmission optical fiber is changed by changing the respective polarization states, and the output beam parameter product from the transmission optical fiber is adjusted.

[0004] Patent Document 1: Japanese Patent Application No. 2017-506769 Summary of the invention

[0005] However, when the technology described in Patent Document 1 is applied to a laser processing machine, if the axis of the incident laser light on the light source side exists coaxially with the incident axis of the transmission optical fiber, the laser light reflected by the workpiece will return to the laser oscillator as the light source according to the distribution centered on the incident axis of the transmission optical fiber. In addition, there is a problem that the reflected laser light may damage the laser oscillator.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to obtain a variable numerical aperture device capable of suppressing damage to a laser oscillator caused by reflected laser light returning in a distribution centered on the incident axis of a transmission optical fiber.

[0007] In order to solve the above-mentioned problems and achieve the purpose, the present invention is a variable numerical aperture device, which reconfigures the spatial distribution or spatial position of multiple lasers emitted from a laser oscillator, so that the reconfigured multiple lasers are focused and emitted into a transmission optical fiber. The variable numerical aperture device has a shading component, which is arranged on the extension line of the optical axis of the transmission optical fiber, and shields the laser from the transmission optical fiber toward the laser oscillator, that is, the reflected laser.

[0008] Effects of the Invention

[0009] The variable numerical aperture device according to the present invention has the effect of being able to suppress damage to a laser oscillator caused by reflected laser light that returns according to a distribution centered on the incident axis of a transmission optical fiber. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a diagram schematically showing an example of the structure of the laser processing machine according to the first embodiment.

[0011] Figure 2 This is a diagram schematically showing an example of the structure of the variable numerical aperture device involved in embodiment 1.

[0012] Figure 3 This is a side view schematically showing an example of the structure of a beam interval changing section in the variable numerical aperture device according to the first embodiment.

[0013] Figure 4 This is a diagram schematically showing an example of a method of changing the numerical aperture in the variable numerical aperture device according to the first embodiment.

[0014] Figure 5 Yes means Figure 4 A diagram showing an example of a change in the configuration state of the laser within the XY plane.

[0015] Figure 6 This is a diagram showing an example of the hardware configuration of the control device of the laser processing machine according to the first embodiment. DETAILED DESCRIPTION

[0016] Hereinafter, a variable numerical aperture device, a laser device, and a laser processing machine according to embodiments of the present invention will be described in detail with reference to the drawings.

[0017] Implementation method 1.

[0018] Figure 1 1 is a diagram schematically showing an example of the configuration of a laser processing machine according to Embodiment 1. The laser processing machine 1 is a machine tool that processes a workpiece 61 as a workpiece by irradiating a laser beam L as a laser beam to the workpiece 61 as a workpiece.

[0019] The laser processing machine 1 includes: a laser device 10 that outputs laser light L; a transmission optical fiber 40 that transmits the laser light L; a processing head 50 that irradiates the laser light L from the transmission optical fiber 40 onto a workpiece 61; a processing table 60 that supports the workpiece 61; and a control device 70 that controls the entire laser processing machine 1.

[0020] The laser device 10 includes a laser oscillator 20 which is a light source, and a variable numerical aperture device 30 which changes the incident numerical aperture (NA) to a transmission optical fiber 40 .

[0021] The laser oscillator 20 is a light source such as a solid laser, a gas laser, or a semiconductor laser that emits laser light LA ​​and LB. Here, the laser oscillator 20 emits a plurality of laser light LA ​​and LB. One laser oscillator 20 may emit a plurality of laser light LA ​​and LB, or a plurality of laser oscillators 20 may emit one laser light LA ​​and LB respectively. The laser oscillator 20 is arranged in such a manner that the positions of the plurality of laser light LA ​​and LB are symmetrical with respect to the extension line of the optical axis of the transmission optical fiber 40. The laser oscillator 20 causes the plurality of laser light LA ​​and LB to be emitted into the variable numerical aperture device 30.

[0022] The variable numerical aperture device 30 reconfigures the spatial distribution or spatial position of the plurality of lasers LA and LB injected from the laser oscillator 20, focuses the reconfigured plurality of lasers LA and LB and injects them into the incident end of the transmission optical fiber 40, and connects the laser oscillator 20 and the transmission optical fiber 40. The laser light after focusing the lasers LA and LB transmitted in the transmission optical fiber 40 is called laser light L. The numerical aperture indicates the size of the light receiving angle and the emission angle in the transmission optical fiber 40, and the variable numerical aperture device 30 can also be called a device that changes the incident numerical aperture and the emission numerical aperture of the transmission optical fiber 40.

[0023] The acceptance angle of the transmission optical fiber 40 has a maximum value. The maximum value is the maximum acceptance angle at which the laser light L can be transmitted in the transmission optical fiber 40 by total reflection. On the other hand, the incident numerical aperture also has a minimum value corresponding to the aforementioned maximum value of the acceptance angle. The minimum value is determined by the quality of the beam output from the laser oscillator 20 and the structure of the variable numerical aperture device 30 described later. The variable numerical aperture device 30 changes the incident numerical aperture so that it is between the minimum value and the maximum value of the incident numerical aperture. The incident numerical aperture is achieved by reconfiguring the spatial distribution or spatial position of multiple lasers LA, LB. An example of reconfiguration of multiple lasers LA, LB is changing the beam spacing of multiple lasers LA, LB. In addition, in Figure 1 In FIG. 3 , a variable numerical aperture device 30 is schematically shown. Figure 1 In FIG. 1 , the dotted arrows shown between the laser oscillator 20 and the incident end of the transmission optical fiber 40 indicate that the laser light LA ​​and LB pass through the variable numerical aperture device 30 .

[0024] The incident end of the transmission optical fiber 40 is connected to the laser device 10, specifically, the variable numerical aperture device 30, and the output end is connected to the processing head 50. The laser light L transmitted in the transmission optical fiber 40 is incident on the processing head 50. The transmission optical fiber 40 is an optical waveguide for transmitting the laser light L, and has a core and a cladding covering the periphery of the core with a material having a lower refractive index than the core. With the above-mentioned structure, the transmission optical fiber 40 transmits the laser light L having an incident numerical aperture less than or equal to the maximum value of the incident numerical aperture of the transmission optical fiber 40 by total reflection.

[0025] The processing head 50 is connected to the laser device 10 via the transmission optical fiber 40, and irradiates the laser light L transmitted in the transmission optical fiber 40 to the workpiece 61. The processing head 50 has a transmission optical system 51 that guides the laser light L to the emission port of the processing head 50, and irradiates the laser light L to a predetermined position on the workpiece 61. The transmission optical system 51 has a focusing optical system that focuses the laser light L from the transmission optical fiber 40, although not shown in the figure. The laser light L emitted from the processing head 50 is incident on the workpiece 61. Figure 1 In FIG. 6 , the dotted arrow between the emission end of the transmission optical fiber 40 and the workpiece 61 indicates that the laser light L emitted from the emission end of the transmission optical fiber 40 reaches the workpiece 61 .

[0026] The processing table 60 is a table for placing the workpiece 61. The processing table 60 preferably has a fixing mechanism for fixing the workpiece 61 so that the workpiece 61 does not move during processing.

[0027] The laser processing machine 1 moves the processing table 60 relative to the processing head 50, thereby relatively moving the laser light L and the workpiece 61. In addition, the laser processing machine 1 may relatively move the laser light L and the workpiece 61 without moving the processing table 60. The laser processing machine 1 may also fix the position of the processing table 60 and control the incident position of the laser light L in the workpiece 61.

[0028] The control device 70 sends control signals to the laser oscillator 20, the variable numerical aperture device 30, the processing head 50 and the processing table 60 respectively to control their respective actions. The laser oscillator 20 outputs lasers LA and LB according to the control signal. The variable numerical aperture device 30 operates according to the control signal to change the incident numerical aperture of the laser L to the transmission optical fiber 40. The processing head 50 operates according to the control signal. The processing table 60 operates according to the control signal. As described above, the control device 70 controls the laser oscillator 20, the variable numerical aperture device 30, the processing head 50 and the processing table 60 respectively. In addition, the processing unit of the control device 70 that controls the action of the variable numerical aperture device 30 is a control device that causes the variable numerical aperture device 30 to operate, and can be considered as a part of the variable numerical aperture device 30.

[0029] The control device 70 changes the incident numerical aperture to the transmission optical fiber 40 by controlling the variable numerical aperture device 30, thereby adjusting the output numerical aperture at the output end of the transmission optical fiber 40. That is, the variable numerical aperture device 30 and the control device 70 control the incident numerical aperture of the transmission optical fiber 40, thereby controlling the output numerical aperture of the transmission optical fiber 40.

[0030] Next, the details of the variable numerical aperture device 30 will be described. Figure 2 FIG. 1 is a diagram schematically showing an example of the structure of a variable numerical aperture device according to Embodiment 1. Figure 2 In FIG. 1 , not only the variable numerical aperture device 30 but also the laser oscillator 20 and the transmission optical fiber 40 are shown. Figure 2 3 shows a case where the variable numerical aperture device 30 changes the interval between the two laser beams LA and LB, that is, the laser beam LA from the laser oscillator 20A and the laser beam LB from the laser oscillator 20B, to change the incident numerical aperture to the transmission optical fiber 40. If the traveling direction of the laser beams LA and LB in the laser oscillators 20A and 20B is set as the Z-axis direction, and two axes perpendicular to the Z-axis and each other are set as the X-axis and the Y-axis, the laser oscillators 20A and 20B are arranged in a row along the Y-axis direction. In addition, the laser oscillators 20A and 20B are arranged symmetrically with respect to the extension line, which is the line extending the optical axis of the transmission optical fiber 40.

[0031] The variable numerical aperture device 30 includes a beam interval changer 31 that changes the interval between the plurality of laser beams LA and LB, that is, the beam interval, and a focusing optical system 33 that focuses the laser beams LA and LB after the beam interval change at the incident end of the transmission optical fiber 40 .

[0032] When the beam characteristics of the plurality of laser beams LA and LB have directivity in the XY plane, the beam interval changing section 31 includes two or more beam interval changing units 32-1 and 32-2. Figure 2In the example, the beam spacing change unit 31 has two beam spacing change units 32-1 and 32-2. The beam spacing change unit 32-1 changes the beam spacing in the first direction perpendicular to the Z axis. The beam spacing change unit 32-2 changes the beam spacing in the second direction different from the first direction. The beam spacing change unit 31 changes the beam spacing ΔP1-1 of the lasers LA and LB emitted from the laser oscillators 20A and 20B to a beam spacing ΔP2-2. In this case, the first direction is the X-axis direction, and the second direction is the Y-axis direction. In addition, the change in the spacing between the lasers LA and LB is to change the position of the lasers LA and LB in the XY plane. Therefore, the beam spacing change unit 31 can also be called a device that changes the configuration of multiple lasers LA and LB in the XY plane.

[0033] The focusing optical system 33 focuses the laser beams LA and LB after the beam interval change by the beam interval changer 31 and injects the focused laser beams into the transmission optical fiber 40. The focusing optical system 33 includes one or more lenses. Figure 2 In the example of FIG, the light-converging optical system 33 has a single lens, but may have two or more lenses. In addition, when the light-converging optical system 33 has two or more lenses, the incident numerical aperture NA_in to the transmission optical fiber 40 may be changed in the light-converging optical system 33.

[0034] The transmission optical fiber 40 is Figure 2 As shown, it has a core 41 and a cladding 42 covering the core 41 and made of a material with a lower refractive index than the core 41. The laser light L focused on the incident end of the transmission optical fiber 40 travels along the path shown by the dotted line by total reflection and is emitted from the output end with an output numerical aperture NA_out determined corresponding to the incident numerical aperture NA_in.

[0035] Figure 3 1 is a side view schematically showing an example of the structure of the beam interval changing section in the variable numerical aperture device according to Embodiment 1. As described above, the beam interval changing section 31 includes the beam interval changing means 32 - 1 and the beam interval changing means 32 - 2 .

[0036] The beam interval changing unit 32-1 has a beam reconfiguration unit 321-1 and a light shielding component 326-1. The beam reconfiguration unit 321-1 is composed of two planar transmission plates 322-1 and 323-1 that transmit the laser light LA ​​and LB. The two transmission plates 322-1 and 323-1 of the beam reconfiguration unit 321-1 are rectangular plate-shaped planar substrates of the same size. The two transmission plates 322-1 and 323-1 are arranged at a predetermined interval in the Y-axis direction. A rotation axis not shown is set at the center of the ZX plane of the transmission plate 322-1, and a rotation mechanism not shown is set on the rotation axis. As a result, the transmission plate 322-1 rotates around the rotation axis not shown. A rotation axis 325-1 is set at the center of the ZX plane of the transmission plate 323-1, and a rotation mechanism not shown is set on the rotation axis 325-1. Thus, the transmission plate 323-1 rotates around the rotation axis 325-1. The two transmission plates 322-1 and 323-1 are arranged to be tilted in opposite directions at the same angle θ1, with the straight line A1 passing through the rotation axis 325-1 and parallel to the X axis as a reference. If the clockwise rotation direction from the straight line A1 is set as positive and the counterclockwise rotation direction is set as negative, then Figure 3 In the example, the transmission plate 322-1 is arranged to be tilted at an angle θ1, and the transmission plate 323-1 is arranged to be tilted at an angle -θ1. The two transmission plates 322-1 and 323-1 are arranged symmetrically with respect to the optical axis of the transmission optical fiber 40. The rotation mechanism rotates the two transmission plates 322-1 and 323-1 respectively according to the instruction from the control device 70.

[0037] The light shielding member 326-1 is disposed on the extension of the optical axis of the transmission optical fiber 40, and is a member for shielding the laser light, i.e., the reflected laser light, from the transmission optical fiber 40 toward the laser oscillators 20A and 20B. That is, the light shielding member 326-1 is disposed to prevent the reflected laser light reflected by the workpiece 61 from returning to the laser oscillator 20. Figure 3 In the example of FIG. 1 , the light shielding member 326 - 1 is disposed between the two transmission plates 322 - 1 and 323 - 1 and has a shape extending in the X-axis direction.

[0038] The beam interval changing unit 32-2 has a beam reconfiguration unit 321-2 and a light shielding component 326-2. The beam reconfiguration unit 321-2 is composed of two planar transmission plates 322-2 and 323-2 that transmit the laser light LA ​​and LB. The two transmission plates 322-2 and 323-2 of the beam reconfiguration unit 321-2 are rectangular plate-shaped planar substrates of the same size. The two transmission plates 322-2 and 323-2 are arranged at a predetermined interval in the X-axis direction. A rotation axis 324-2 is provided at the center of the YZ plane of the transmission plate 322-2, and a rotation mechanism not shown in the figure is provided on the rotation axis 324-2. As a result, the transmission plate 322-2 rotates around the rotation axis 324-2. A rotation axis 325-2 is provided at the center of the YZ plane of the transmission plate 323-2, and a rotation mechanism not shown in the figure is provided on the rotation axis 325-2. Thus, the transmission plate 323-2 rotates around the rotation axis 325-2. The two transmission plates 322-2 and 323-2 are arranged to be inclined at the same angle in opposite directions with respect to a straight line passing through the rotation axes 324-2 and 325-2 and parallel to the Y axis as a reference. The two transmission plates 322-2 and 323-2 are arranged symmetrically with respect to the optical axis of the transmission optical fiber 40. The rotation mechanism rotates the two transmission plates 322-2 and 323-2 respectively according to the instruction from the control device 70.

[0039] The light shielding member 326-2 is a member that is disposed on the extension of the optical axis of the transmission optical fiber 40 and shields the reflected laser light from the transmission optical fiber 40 toward the laser oscillators 20A and 20B. That is, the light shielding member 326-2 is disposed to suppress the reflected laser light reflected by the workpiece 61 from returning to the laser oscillator 20. In one example, the light shielding member 326-2 is disposed between the two transmission plates 322-2 and 323-2 and can be set to a shape extending in the Y-axis direction.

[0040] The transmission plates 322-1, 322-2, 323-1, 323-2 are preferably made of an optically isotropic material that is transparent to the wavelength of the laser light LA, LB oscillated by the laser oscillator 20. When the laser oscillators 20A, 20B are fiber lasers that oscillate laser light LA, LB at around 1070 nm, an example of the transmission plates 322-1, 322-2, 323-1, 323-2 is a glass substrate such as synthetic quartz.

[0041] The light shielding components 326-1 and 326-2 are respectively provided for the plurality of beam interval changing units 32-1 and 32-2, and are located on the transmission optical fiber 40 side of each beam interval changing unit 32-1 and 32-2. The light shielding in the light shielding components 326-1 and 326-2 only needs to reflect or absorb the laser light. The material used for the light shielding components 326-1 and 326-2 depends on the wavelength of the laser light L emitted by the laser oscillator 20. An example of the light shielding components 326-1 and 326-2 in the case of light shielding by reflection is copper after surface treatment. An example of the light shielding components 326-1 and 326-2 in the case of light shielding by absorption is aluminum after aluminum oxide film treatment. In addition, the light shielding components 326-1 and 326-2 may have a cooling mechanism. The cooling mechanism includes a pipe provided inside or in contact with the light shielding members 326-1 and 326-2 and a refrigerant supply unit for flowing a refrigerant to the pipe. An example of the refrigerant is water. By flowing water from the refrigerant supply unit to the pipe, the temperature rise of the light shielding members 326-1 and 326-2 is suppressed.

[0042] The light shielding component 326-1 is disposed between the two transmission plates 322-1 and 323-1, and the light shielding component 326-2 is disposed between the two transmission plates 322-2 and 323-2. Therefore, within the variable numerical aperture device 30, at least one of the size and the configuration of the light shielding components 326-1 and 326-2 is determined so that the output loss of the multiple lasers LA and LB caused by the blocking in the light shielding components 326-1 and 326-2 is less than or equal to 10% when the spatial distribution or spatial position of the multiple lasers LA and LB incident is closest. Therefore, Figure 3 The shapes of the light shielding members 326 - 1 and 326 - 2 shown are just examples, and other shapes are also possible.

[0043] The lasers LA and LB have parabolic beam intensities. That is, the lasers LA and LB have a Gaussian distribution in which the beam intensity is high at the center and decreases toward the periphery. In this case, the beam intensity decreases from the peak position at 1 / e 2The beam width at the reduced position is defined as the Gaussian beam diameter. When this Gaussian beam diameter is used, the portion of the laser LA and LB that deviates from the Gaussian beam diameter becomes about 10% of the beam diameter of the laser LA and LB. In the laser LA and LB, if it is considered that the portion of the Gaussian beam diameter passes through, as described above, it is preferable to set the output loss caused by the obstruction in the shading components 326-1 and 326-2 to be less than or equal to 10%. In addition, the optical components constituting the laser processing machine 1 are generally mostly optically designed based on the Gaussian beam diameter. Therefore, it is also preferable to design so that the output loss of the laser LA and LB caused by the obstruction in the shading components 326-1 and 326-2 is less than or equal to 10%.

[0044] Here, a method of adjusting the beam interval in the variable numerical aperture device 30 will be described. Figure 4 FIG. 1 is a diagram schematically showing an example of a method of changing the numerical aperture in the variable numerical aperture device according to Embodiment 1. Figure 4 In the figure, only Figure 2 The beam interval changing units 32-1 and 32-2 of the numerical aperture variable device 30 are shown in FIG. Figure 4 In the figure, for convenience, a side view viewed from the Y-axis direction, that is, a view of the ZX plane, and a side view viewed from the X-axis direction, that is, a view of the YZ plane, are shown simultaneously.

[0045] exist Figure 4 In the beam interval changing section 31 of the numerical aperture variable device 30, the beam interval changing unit 32-1 is arranged on the laser oscillator 20 side, and the beam interval changing unit 32-2 is arranged on the transmission optical fiber 40 side. The beam interval changing unit 32-1 does not change the beam interval in the Y-axis direction, but changes the beam interval in the X-axis direction, and the beam interval changing unit 32-2 does not change the beam interval in the X-axis direction, but changes the beam interval in the Y-axis direction. In addition, this is an example, and the beam interval changing unit 32-1 and the beam interval changing unit 32-2 only need to change the beam intervals in arbitrary directions different from each other.

[0046] exist Figure 4 In the example, the transmission plates 322-1 and 323-1 of the beam interval changing unit 32-1 are rotated by θ1 and -θ1 respectively with respect to the straight line A1. In addition, the transmission plates 322-2 and 323-2 of the beam interval changing unit 32-2 are rotated by θ2 and -θ2 respectively with respect to the straight line A2. The straight line A2 is a straight line passing through the rotation axes 324-2 and 325-2 and parallel to the X axis. θ1 and θ2 are arbitrarily set so that the incident numerical aperture NA_in of the transmission optical fiber 40 becomes a predetermined value.

[0047] Laser oscillators 20A and 20B are arranged symmetrically with respect to the optical axis of transmission fiber 40 at a distance in the Y-axis direction. Laser oscillators 20A and 20B output laser light LA ​​and LB, respectively. The beam interval of laser light LA ​​and LB in the X-axis direction is ΔP1-1x, and the beam interval in the Y-axis direction is ΔP1-1y.

[0048] Figure 5 Yes means Figure 4 An example of a change in the configuration state of the laser within the XY plane is shown in FIG. Figure 4 The configuration state in the plane perpendicular to the traveling direction of the laser LA and LB at positions R1, R2, and R3 in the optical path of the laser LA and LB. Before entering the beam interval changing unit 32-1, as shown in the configuration state C1 at the position R1, the lasers LA and LB are in a state of being configured with intervals in the Y-axis direction. In addition, the lasers LA and LB have a beam shape that is flattened in the X-axis direction, that is, an elliptical beam shape with a longer diameter in the Y-axis direction than in the X-axis direction. Moreover, the lasers LA and LB are incident on the beam interval changing unit 32-1 in the state of the configuration state C1.

[0049] Back to Figure 4 In the beam spacing changing unit 32-1, two transmission plates 322-1 and 323-1 are arranged at a distance in the Y-axis direction, and the rotation axes 324-1 and 325-1 are parallel to the Y-axis. Here, the transmission plate 322-1 is arranged to transmit the laser LA from the laser oscillator 20A, and the transmission plate 323-1 is arranged to transmit the laser LB from the laser oscillator 20B. In addition, in the beam spacing changing unit 32-1, the two transmission plates 322-1 and 323-1 can rotate around the Y-axis. Here, as described above, with the straight line A1 as a reference, the transmission plate 322-1 is arranged to be tilted at an angle θ1, and the transmission plate 323-1 is arranged to be tilted at an angle -θ1. By setting the beam reconfiguration unit 321-1 to the above configuration, the beam spacing in the X-axis direction can be changed.

[0050] Lasers LA and LB are incident on the beam interval changing unit 32-1. Here, laser LA is incident on the transmission plate 322-1, and laser LB is incident on the transmission plate 323-1. When lasers LA and LB are incident on the transmission plates 322-1 and 323-1, they are refracted. It seems that the lasers LA and LB are refracted in the direction with the incident angle, that is, in the ZX plane, and the lasers LA and LB go straight in the direction without the incident angle, that is, in the YZ plane. In addition, the two transmission plates 322-1 and 323-1 are inclined in opposite directions at the same angle θ1 relative to the straight line A1. As a result, in the ZX plane, the two lasers LA and LB are refracted in the direction of separation. On the other hand, in the YZ plane, the lasers LA and LB are not refracted. Parts of the lasers LA and LB will hit the light shielding component 326-1, but in the ZX plane, the laser LA passes through the far end side of the light shielding component 326-1 in the Y-axis direction, and the laser LB passes through the near end side of the light shielding component 326-1 in the Y-axis direction.

[0051] The arrangement state of the laser beams LA and LB output from the beam interval changing unit 32-1 is Figure 5 The configuration state C2 at the position R2. The dotted ellipse in the configuration state C2 shows the positions of the lasers LA and LB in the configuration state C1. Figure 5 As shown, the laser light LA ​​and the laser light LB move in opposite directions and at the same distance in the X-axis direction.

[0052] Back to Figure 4 The beam interval of the laser beams LA and LB output from the beam interval changing unit 32-1 in the X-axis direction is set to ΔP1-2x, and the beam interval in the Y-axis direction is set to ΔP1-2y. Figure 4 In the example, the beam interval ΔP1-2x of the laser beams LA and LB in the X-axis direction outputted from the beam interval changing unit 32-1 becomes larger than the beam interval ΔP1-1x before the incident beam. On the other hand, the beam interval ΔP1-2y of the laser beams LA and LB in the Y-axis direction outputted from the beam reconfiguration unit 321-1 is equal to the beam interval ΔP1-1y before the incident beam.

[0053] Here, the beam interval of the two lasers LA and LB input to the beam interval changing unit 32-2 in the X-axis direction is ΔP2-1x, and the beam interval in the Y-axis direction is ΔP2-1y. In addition, the beam interval ΔP2-1x in the X-axis direction is equal to ΔP1-2x, and the beam interval ΔP2-1y in the Y-axis direction is equal to ΔP1-2y.

[0054] The two lasers LA and LB described above are incident on the beam interval changing unit 32-2. Here, the laser LA is incident on the transmission plate 322-2, and the laser LB is incident on the transmission plate 323-2. The lasers LA and LB are refracted when they are incident on the transmission plates 322-2 and 323-2. As with the beam interval changing unit 32-1, the lasers LA and LB appear to be refracted in the YZ plane in the direction with the incident angle, and appear to go straight in the ZX plane in the direction without the incident angle. In addition, the two transmission plates 322-2 and 323-2 are inclined in opposite directions at the same angle θ2 with respect to the straight line A2. As a result, the lasers LA and LB are not refracted in the ZX plane. On the other hand, in the YZ plane, the two lasers LA and LB are refracted in the direction close to each other. Parts of the lasers LA and LB hit the light shielding component 326-2, but in the YZ plane, the laser LA passes through the far end side of the light shielding component 326-2, and the laser LB passes through the near end side of the light shielding component 326-2. Thus, the beam interval of the two laser beams LA and LB output from the beam interval changing unit 32 - 2 becomes ΔP2 - 2x in the X-axis direction, and the beam interval in the Y-axis direction becomes ΔP2 - 2y. Figure 4 In the example, the beam interval ΔP2-2x is equal to the beam interval ΔP2-1x in the X-axis direction of the two lasers LA and LB before entering the beam interval changing unit 32-2. On the other hand, the beam interval ΔP2-2y is smaller than the beam interval ΔP2-1y in the Y-axis direction of the two lasers LA and LB before entering the beam interval changing unit 32-2.

[0055] The arrangement state of the laser beams LA and LB output from the beam interval changing unit 32-2 is Figure 5 The configuration state C3 at the position R3. The dotted ellipse in the configuration state C3 shows the positions of the lasers LA and LB in the configuration state C2. Figure 5 As shown, the laser light LA ​​and the laser light LB move in opposite directions and at the same distance in the Y-axis direction and are located on the X-axis.

[0056] As described above, the two elliptical lasers LA and LB extending in the Y-axis direction and arranged at a distance in the Y-axis direction as shown in the arrangement state C1 pass through the two beam interval changing units 32-1 and 32-2, and are thus arranged at a distance in the X-axis direction as shown in the arrangement state C3. That is, the lasers LA and LB can be re-arranged by the two beam interval changing units 32-1 and 32-2.

[0057] When the beam qualities of the laser lights LA and LB in the X-axis direction and the Y-axis direction are different, the beam diameter and the divergence angle when the laser lights L are coupled can be changed by rearranging the laser lights LA and LB as described above.

[0058] It is known that the beam quality is represented by the product of the beam diameter and the divergence angle. The smaller the beam quality value obtained as described above is, the better the quality of the laser light LA ​​and LB is.

[0059] The beam diameter in the case of one laser can be obtained by the Gaussian beam diameter as described above. On the other hand, for the beam diameter when multiple lasers LA and LB are coupled, the beam diameter determined based on the energy distribution formed by the multiple lasers LA and LB can be used. There are various ways to define the beam diameter, but here, the diameter that accommodates a specified proportion of energy within the energy of the laser is considered to be the beam diameter. The beam diameter of the multiple lasers LA and LB coupled in the above manner becomes different depending on the configuration of the multiple lasers LA and LB. And, as a result, the beam quality changes.

[0060] Yes Figure 5 The case where multiple lasers LA and LB are coupled in configuration state C1, that is, the case where two lasers LA and LB are coupled in the Y-axis direction, is compared with the case where multiple lasers LA and LB are coupled in configuration state C3, that is, the case where two lasers LA and LB are coupled in the X-axis direction. The two lasers LA and LB, which are elliptical and flattened in the X-axis direction, are arranged at intervals in the Y-axis direction in configuration state C1, and are arranged at intervals in the X-axis direction in configuration state C3. The beam diameter of the lasers LA and LB in the Y-axis direction is larger than the beam diameter in the X-axis direction, so it is considered that the beam quality in the Y-axis direction is worse than the beam quality in the X-axis direction. In addition, in the case where the energy containing a specified proportion of the total energy is considered to be the beam diameter, the narrower the interval between the two lasers LA and LB, the smaller the beam diameter becomes. If these are taken together, it is considered that configuration state C3 configured in the X-axis direction has good beam quality compared to configuration state C1 in which the lasers LA and LB are arranged in the Y-axis direction at intervals. Therefore, in Figure 4 In the embodiment, the two laser beams LA and LB are rearranged using the two beam interval changing units 32 - 1 and 32 - 2 so as to change from the arrangement state C1 to the arrangement state C3 .

[0061] In addition, the beam spacing changing unit 32-1 and the beam spacing changing unit 32-2 change the directions of the beam spacing in different directions, and the tilt angle can also be set arbitrarily. As described above, the shape of the laser LA and LB in the XY plane has directionality in the X-axis and Y-axis, so according to the shape, the displacement of the beam position in the X-axis direction and the Y-axis direction is set so that the numerical aperture of the laser L after the multiple lasers LA and LB are coupled is roughly the same in the X-axis direction and the Y-axis direction. The reason why the numerical aperture of the laser L is roughly the same in the X-axis direction and the Y-axis direction is that the output numerical aperture NA_out of the transmission optical fiber 40 depends on the larger of the incident numerical aperture NA_in.

[0062] The relationship between the tilt angle of the transmission plates 322-1, 322-2, 323-1, 323-2 and the beam interval is obtained in advance by experiments. Thus, the tilt angle of the transmission plates 322-1, 322-2, 323-1, 323-2 can be obtained so that the beam quality of the two lasers LA and LB output from the beam interval changing unit 32-2 when coupled becomes a desired value.

[0063] According to the above-mentioned consideration of beam quality, the best beam quality can be obtained by overlapping multiple lasers LA and LB in a consistent manner. However, the reflected laser light reflected by the workpiece 61 from the laser L of the processing head 50 sometimes returns to the laser oscillator 20 side according to the distribution centered on the optical axis of the transmission optical fiber 40. Assuming the above situation, in embodiment 1, shielding components 326-1 and 326-2 are arranged at positions corresponding to the optical axis of the transmission optical fiber 40 on the output side of the laser LA and LB of each beam interval change unit 32-1 and 32-2. By configuring the shielding components 326-1 and 326-2, it is impossible to overlap multiple lasers LA and LB in a consistent manner. That is, there is a limit to reducing the interval between the two lasers LA and LB. In the case where the shielding components 326-1 and 326-2 are present, the beam interval that minimizes the beam quality of the two lasers LA and LB is obtained. When two laser beams LA and LB having a beam interval that minimizes the beam quality are incident on the incident end of the transmission optical fiber 40 via the condensing optical system 33, the light receiving angle of the transmission optical fiber 40 becomes minimum. That is, the incident numerical aperture NA_in of the transmission optical fiber 40 becomes minimum.

[0064] In addition, in order to minimize the beam quality of the two lasers LA and LB, the multiple lasers LA and LB must be arranged symmetrically with respect to the extension line of the optical axis of the transmission optical fiber 40. The reason is that when the two lasers LA and LB are not symmetrical with respect to the extension line of the optical axis of the transmission optical fiber 40, the incident angle of one of the two lasers LA and LB becomes larger than that of the other laser. The output numerical aperture NA_out of the transmission optical fiber 40 depends on the larger incident numerical aperture NA_in, so in order to reduce the output numerical aperture NA_out of the transmission optical fiber 40, the incident numerical aperture NA_in of the transmission optical fiber 40 needs to be reduced. In order to reduce the incident numerical aperture NA_in of the transmission optical fiber 40 as much as possible, it is necessary to inject the laser from the extension line of the optical axis of the transmission optical fiber 40. Moreover, when configuring two lasers LA and LB, the incident numerical aperture NA_in of the transmission optical fiber 40 becomes minimum, so that the output loss of the lasers LA and LB caused by the blocking in the shading parts 326-1 and 326-2 is less than or equal to 10%, and the two lasers LA and LB that are closest in spatial distribution or spatial position are symmetrical with respect to the extension line of the optical axis of the transmission optical fiber 40.

[0065] As described above, not all of the laser light L incident on the transmission optical fiber 40 is transmitted by total reflection. The laser light L transmitted in the transmission optical fiber 40 by total reflection is limited to the laser light L incident at an angle less than or equal to the maximum value of the light acceptance angle of the transmission optical fiber 40. The laser light L incident at an angle greater than the maximum value of the light acceptance angle of the transmission optical fiber 40 cannot be transmitted in the transmission optical fiber 40, and becomes radiated light and is lost. When the light acceptance angle of the transmission optical fiber 40 is at the maximum value, the incident numerical aperture NA_in of the transmission optical fiber 40 becomes maximum.

[0066] As described above, the numerical aperture variable device 30 can make the incident numerical aperture NA_in of the transmission optical fiber 40 variable between the minimum value and the maximum value by adjusting the rotation angle of the transmission plates 322-1, 322-2, 323-1, 323-2 of the beam interval change units 32-1, 32-2. That is, if the condition is converged between the minimum value and the maximum value of the incident numerical aperture, the beam quality of the laser light L after coupling the plurality of laser lights LA and LB, more specifically, the beam diameter or the divergence angle can be changed by adjusting the rotation angle of the transmission plates 322-1, 322-2, 323-1, 323-2.

[0067] At this time, restrictions may be placed on the operations of the beam interval changing units 32 - 1 and 32 - 2 so that the incident numerical aperture NA_in does not exceed the maximum value of the incident numerical aperture of the transmission optical fiber 40 .

[0068] In addition, if Figure 2As shown, the output numerical aperture NA_out at the output end of the transmission optical fiber 40 changes in accordance with the incident numerical aperture NA_in at the incident end of the transmission optical fiber 40. That is, the output numerical aperture NA_out of the transmission optical fiber 40 can be changed in the same manner as the incident numerical aperture NA_in. As described above, in the first embodiment, the incident numerical aperture NA_in can be greatly changed between the minimum value and the maximum value by the numerical aperture variable device 30, so the variable range of the output numerical aperture NA_out can also be greatly changed in accordance with the incident numerical aperture NA_in.

[0069] In addition, in the above description, the case where the variable numerical aperture device 30 has two beam spacing changing units 32-1 and 32-2 is shown, but this is just an example. In the case where the beam characteristics of the lasers LA and LB emitted from the laser oscillators 20A and 20B are different in the X-axis direction and the Y-axis direction, the variable numerical aperture device 30 only needs to have two or more beam spacing changing units. However, in the case where the beam characteristics of the lasers LA and LB emitted from the laser oscillators 20A and 20B do not have directionality in the X-axis direction and the Y-axis direction, the beam spacing changing unit can be one. In addition, the rotation axes 324-1 and 325-1 of the beam spacing changing unit 32-1 and the rotation axes 324-2 and 325-2 of the beam spacing changing unit 32-2 are perpendicular to each other, but this is also an example. The rotation axes 324-1, 325-1 of the beam interval changing unit 32-1 and the rotation axes 324-2, 325-2 of the beam interval changing unit 32-2 may be in any direction as long as they are perpendicular to the optical axis of the transmission optical fiber 40 and the directions of the rotation axes 324-1, 324-2, 325-1, 325-2 do not coincide with each other.

[0070] The rotational positions of the beam reconfiguration units 321 - 1 and 321 - 2 , that is, the inclinations of the transmission plates 322 - 1 , 322 - 2 , 323 - 1 and 323 - 2 may be arbitrarily controlled, or may be configured to store a set angle in advance and rotate to the set angle by a command from the control device 70 .

[0071] The numerical aperture variable device 30 of the first embodiment includes a plurality of beam interval change units 32-1 and 32-2, which rearrange the plurality of laser beams LA and LB and change the incident numerical aperture NA_in of the transmission optical fiber 40 when the rearranged plurality of laser beams LA and LB are focused and incident on the transmission optical fiber 40. The plurality of beam interval change units 32-1 and 32-2 each include a light shielding member 326-1 and 326-2, which are provided on the transmission optical fiber 40 side and provided in a region including the extension line of the optical axis of the transmission optical fiber 40. Thus, the reflected laser beam reflected by the workpiece 61 and returned to the laser oscillator 20 side according to the distribution centered on the optical axis of the transmission optical fiber 40 can be shielded without passing through the laser oscillator 20 side. That is, the output numerical aperture NA_out of the transmission optical fiber 40 can be controlled while suppressing the malfunction of the laser oscillator 20 due to the reflected laser beam. In addition, even when there is a large amount of reflected laser beam reflected by the workpiece 61, the laser oscillator 20 can be operated without malfunctioning.

[0072] In addition, the beam interval changing unit 32-1 includes two transmission plates 322-1 and 323-1 that can rotate around the rotation axes 324-1 and 325-1, and a rotation mechanism that drives each transmission plate 322-1 and 323-1 around the rotation axes 324-1 and 325-1 to have an arbitrary inclination. The beam interval changing unit 32-2 includes two transmission plates 322-2 and 323-2 that can rotate around the rotation axes 324-2 and 325-2, and a rotation mechanism that drives each transmission plate 322-2 and 323-2 around the rotation axes 324-2 and 325-2 to have an arbitrary inclination. In addition, the laser processing machine 1 includes a control device 70 that controls the inclination of the transmission plates 322-1, 322-2, 323-1, and 323-2 via the rotation mechanism. The control device 70 can change the beam interval of the laser light LA ​​and LB by setting the inclination of the two transmission plates 322-1 and 323-1 of the beam interval change unit 32-1 and the inclination of the two transmission plates 322-2 and 323-2 of the beam interval change unit 32-2 to a predetermined angle. That is, the incident numerical aperture NA_in of the transmission optical fiber 40 can be controlled between the minimum value and the maximum value. In addition, the variable range of the incident numerical aperture NA_in can be increased, so the variable range of the output numerical aperture NA_out of the transmission optical fiber 40 can also be increased.

[0073] Furthermore, the plurality of lasers LA and LB are arranged symmetrically with respect to the extension line of the optical axis of the transmission optical fiber 40. That is, the laser oscillators 20A and 20B, the transmission plates 322-1 and 323-1 of the beam interval change unit 32-1, and the transmission plates 322-2 and 323-2 of the beam interval change unit 32-2 are arranged symmetrically with respect to the extension line of the optical axis of the transmission optical fiber 40. Thus, the beam quality of the laser L including the plurality of lasers LA and LB can be made symmetrical. In addition, even if the plurality of lasers LA and LB have poor beam quality, the lasers LA and LB can be re-arranged so that the beam quality becomes better.

[0074] In one example, the control device 70 is implemented by a circuit in which a processor executes software, that is, a processing circuit. The processing circuit that executes software is, in one example, Figure 6 The control circuit shown. Figure 6 1 is a diagram showing an example of a hardware configuration of a control device for a laser processing machine according to Embodiment 1. A control circuit 100 includes an input unit 101 , a processor 102 , a memory 103 , and an output unit 104 .

[0075] The input unit 101 is an interface circuit that receives data input from the outside of the control circuit 100 and gives it to the processor 102. The output unit 104 is an interface circuit that sends data from the processor 102 or the memory 103 to the outside of the control circuit 100. Figure 6 In the case of the control circuit 100 shown in the figure, the above-mentioned components are realized by the processor 102 reading and executing the program for controlling the laser oscillator 20, the variable numerical aperture device 30, the processing head 50 and the processing table 60 stored in the memory 103. The memory 103 is also used as a temporary memory in each process performed by the processor 102. The processor 102 can output data such as calculation results to the memory 103 for storage, or store data such as calculation results in an auxiliary storage device via the volatile memory of the memory 103.

[0076] The processor 102 is a CPU (also called a Central Processing Unit, a central processing device, a processing device, an arithmetic device, a microprocessor, a microcomputer, a processor, or a DSP (Digital Signal Processor). The memory 103 is, for example, a nonvolatile or volatile semiconductor memory such as a RAM (Random Access Memory), a ROM (Read Only Memory), a flash memory, an EPROM (Erasable Programmable Read Only Memory), an EEPROM (registered trademark) (Electrically Erasable Programmable Read Only Memory), a magnetic disk, a floppy disk, an optical disk, a compact disk, a mini disk, or a DVD (Digital Versatile Disc).

[0077] Figure 6 This is an example of hardware in the case where the control device 70 is implemented by a general-purpose processor 102 and a memory 103, but the control device 70 can also be implemented by a dedicated hardware circuit. The dedicated hardware circuit, that is, the processing circuit is a single circuit, a composite circuit, a programmed processor, a parallel programmed processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a circuit combining them. The above-mentioned structural elements can be implemented by a combination of the control circuit 100 and the dedicated hardware circuit.

[0078] The configuration described in the above embodiment is merely an example, and may be combined with other known technologies. Part of the configuration may be omitted or changed without departing from the spirit and scope of the invention.

[0079] Description of the label

[0080] 1 Laser processing machine, 10 Laser device, 20, 20A, 20B Laser oscillator, 30 Variable numerical aperture device, 31 Beam interval changing unit, 32-1, 32-2 Beam interval changing unit, 33 Converging optical system, 40 Transmission optical fiber, 41 Core, 42 Cladding, 50 Processing head, 51 Transmission optical system, 60 Processing table, 61 Workpiece, 70 Control device, 100 Control circuit, 101 Input unit, 102 Processor, 103 Memory, 104 Output unit, 321-1, 321-2 Beam reconfiguration unit, 322-1, 322-2, 323-1, 323-2 Transmission plate, 324-1, 324-2, 325-1, 325-2 Rotation axis, 326-1, 326-2 Light shielding member, A1, A2 Line, L, LA, LB Laser.

Claims

1. A variable numerical aperture device that reconfigures the spatial distribution or spatial positions of a plurality of laser beams emitted from a laser oscillator, so that the reconfigured plurality of laser beams are focused and emitted to a transmission optical fiber, The variable numerical aperture device is characterized in that: A light shielding member is provided on an extension line of the optical axis of the transmission optical fiber and shields the laser light, ie, reflected laser light, which is the laser light from the transmission optical fiber toward the laser oscillator.

2. The variable numerical aperture device according to claim 1, characterized in that: The light shielding member has a size inside the variable numerical aperture device such that output loss of the plurality of laser beams is less than or equal to 10% when spatial distribution or spatial positions of the plurality of incident laser beams are closest.

3. The variable numerical aperture device according to claim 1 or 2, characterized in that: The light shielding member is arranged inside the variable numerical aperture device so that when the spatial distribution or spatial positions of the incident laser beams are closest, the output loss of the laser beams is less than or equal to 10%.

4. The variable numerical aperture device according to any one of claims 1 to 3, characterized in that: The light shielding member is made of a material that absorbs or reflects the reflected laser light.

5. The variable numerical aperture device according to claim 4, characterized in that: The light shielding member has a cooling mechanism.

6. The variable numerical aperture device according to any one of claims 1 to 5, characterized in that: A plurality of beam interval changing units are provided, wherein the plurality of beam interval changing units change the beam intervals of the plurality of incident laser beams, The light shielding member is provided for each of the plurality of beam interval changing units and is located on the transmission optical fiber side of the beam interval changing unit.

7. The variable numerical aperture device according to claim 6, characterized in that: It also includes a control device, which controls the actions of the plurality of beam interval changing units. Each of the plurality of beam interval changing units comprises: a beam reconfiguration unit including a plurality of transmission plates arranged at predetermined intervals for transmitting the laser beam; and A rotating mechanism that rotates the plurality of transmission plates around a rotation axis. The control device controls the rotation mechanism so that the incident angles of the plurality of laser beams on the plurality of transmission plates become predetermined angles.

8. The variable numerical aperture device according to claim 7, characterized in that: The plurality of laser beams are incident on the variable numerical aperture device symmetrically with respect to an extension line of the optical axis of the transmission optical fiber. The plurality of transmission plates are arranged symmetrically with respect to an extension line of the optical axis of the transmission optical fiber.

9. A laser device, characterized in that: have: The variable numerical aperture device according to any one of claims 1 to 8; and The laser oscillator causes the plurality of laser beams to be incident on the variable numerical aperture device.

10. A laser processing machine, characterized in that: have: The laser device as claimed in claim 9; a transmission optical fiber that transmits the plurality of lasers from the laser device; and A processing head irradiates the plurality of laser beams from the transmission optical fiber onto a processing object.

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