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

Abstract

The present invention is a numerical aperture variable device which reconfigures the spatial distribution or the spatial position of a plurality of lasers (LA, LB) emitted from a laser oscillator, and condenses the reconfigured plurality of lasers (LA, LB) and emits them into a delivery fiber, the numerical aperture variable device having light shielding members (326-1, 326-2) which are provided on the extension line of the optical axis of the delivery fiber, and shield the laser light from the delivery fiber toward the laser oscillator, that is, the reflected laser light.

Description

Technical Field

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

[0002] Laser processing machines typically include: a laser oscillator; a focusing lens that focuses the laser light emitted from the laser oscillator; a transmission fiber that transmits the focused laser light through the focusing lens; and a processing head that directs the laser light from the transmission fiber to a desired location on the workpiece. In the laser processing machine described above, it is known to employ a configuration where multiple laser beams are directed into a single transmission fiber to achieve high output.

[0003] Patent Document 1 discloses a beam parameter adjustment system that modifies the spatial distribution of multiple beams from beam sources having polarization states and a spatially distributed aggregate, causing the beams with the modified spatial distribution to converge at the end face of a transmitting optical fiber. In the technology described in Patent Document 1, by modifying the polarization states of the beams, the spatial distribution of the incident beams into the transmitting optical fiber is changed, thereby adjusting the output beam parameter product from the transmitting optical fiber.

[0004] Patent Document 1: Japanese Patent Publication 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 on the light source side exists coaxially with the incident axis of the transmission optical fiber, the laser reflected from the workpiece will return to the laser oscillator, which serves as the light source, according to a distribution centered on the incident axis of the transmission optical fiber. Moreover, there is a problem that the reflected laser may damage the laser oscillator.

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

[0007] To address the aforementioned issues and achieve the objective, the present invention provides a numerical aperture variable device that reconfigures the spatial distribution or spatial position of multiple laser beams incident from a laser oscillator, thereby focusing the reconfigured laser beams into a transmission optical fiber. The numerical aperture variable device includes a light-shielding component disposed on the extension line of the optical axis of the transmission optical fiber to block the laser beams (i.e., reflected laser beams) traveling from the transmission optical fiber toward the laser oscillator.

[0008] The effects of the invention

[0009] The numerical aperture variable device involved in this invention has the following effect: it can suppress damage to the laser oscillator caused by reflected laser light returning from a distribution centered on the incident axis of the transmission fiber. Attached Figure Description

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

[0011] Figure 2 This is a diagram schematically illustrating an example of the structure of the numerical aperture variable device according to Embodiment 1.

[0012] Figure 3 This is a side view schematically illustrating an example of the structure of the beam spacing changing section in the numerical aperture variable device according to Embodiment 1.

[0013] Figure 4 This is a diagram schematically illustrating an example of a method for changing the numerical aperture in the numerical aperture variable device according to Embodiment 1.

[0014] Figure 5 It means Figure 4 A diagram illustrating an example of the changes in the configuration state of a laser in the XY plane.

[0015] Figure 6 This is a diagram illustrating an example of the hardware structure of the control device for the laser processing machine according to Embodiment 1. Detailed Implementation

[0016] The numerical aperture variable device, laser device, and laser processing machine involved in the embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0017] Implementation method 1.

[0018] Figure 1 This is a diagram schematically illustrating an example of the structure of the laser processing machine according to Embodiment 1. The laser processing machine 1 is a working machine that processes the workpiece 61 by irradiating the workpiece 61, which is the workpiece, with a laser L, which is the laser beam.

[0019] The laser processing machine 1 includes: a laser device 10 that outputs laser L; a transmission fiber 40 that transmits laser L; a processing head 50 that irradiates workpiece 61 with laser L from transmission fiber 40; a processing worktable 60 that supports 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 numerical aperture variable device 30, which changes the incident numerical aperture (NA) of the opposing transmission fiber 40.

[0021] The laser oscillator 20 is a light source that emits lasers LA and LB from a solid-state laser, gas laser, semiconductor laser, etc. Here, the laser oscillator 20 emits multiple lasers LA and LB. It can be a single laser oscillator 20 emitting multiple lasers LA and LB, or multiple laser oscillators 20 each emitting one laser LA and LB. The laser oscillator 20 is configured so that the positions of the multiple lasers LA and LB are symmetrical with respect to the extension of the optical axis of the transmission fiber 40. The laser oscillator 20 directs the multiple lasers LA and LB into the numerical aperture variable device 30.

[0022] The numerical aperture variable device 30 reconfigures the spatial distribution or position of multiple lasers LA and LB emitted from the laser oscillator 20, focuses the reconfigured lasers LA and LB, and directs them into the incident end of the transmission fiber 40, connecting the laser oscillator 20 and the transmission fiber 40. The laser LA and LB transmitted in the transmission fiber 40, after being focused, is called laser L. Numerical aperture represents the size of the light-receiving angle and the light-emitting angle in the transmission fiber 40. The numerical aperture variable device 30 can also be called a device that changes the incident numerical aperture and the emitted numerical aperture of the transmission fiber 40.

[0023] The optical fiber 40 has a maximum angle of reception. This maximum angle is the largest angle at which the laser L can be transmitted through the optical fiber 40 via total internal reflection. On the other hand, the incident numerical aperture, corresponding to the aforementioned maximum angle of reception, also has a minimum value. This minimum value is determined by the beam quality output from the laser oscillator 20 and the construction of the numerical aperture variable device 30, described later. The numerical aperture variable device 30 changes the incident numerical aperture to a value between the minimum and maximum. The change in the incident numerical aperture is achieved through the spatial distribution or reconfiguration of the spatial positions of the multiple lasers LA and LB. An example of reconfiguration of the multiple lasers LA and LB is the change in the beam spacing of the multiple lasers LA and LB. Furthermore, in Figure 1 The numerical aperture variable device 30 is schematically shown in the diagram. Figure 1 In the diagram, the dashed arrows shown between the laser oscillator 20 and the incident end of the transmission fiber 40 indicate the case where the lasers LA and LB pass through the numerical aperture variable device 30.

[0024] The incident end of the transmission fiber 40 is connected to the laser device 10, specifically to the numerical aperture variable device 30, and the exit end is connected to the processing head 50. The laser L transmitted in the transmission fiber 40 is directed into the processing head 50. The transmission fiber 40 is an optical waveguide for the transmission of the laser L, having a core and a cladding surrounding the core made of a material with a refractive index lower than that of the core. With the configuration described above, the transmission fiber 40 transmits the laser L, which has an incident numerical aperture less than or equal to the maximum value of the incident numerical aperture of the transmission fiber 40, via total internal reflection.

[0025] The processing head 50 is connected to the laser device 10 via a transmission optical fiber 40, and irradiates the workpiece 61 with the laser L transmitted in the transmission optical fiber 40. The processing head 50 has a transmission optical system 51 that guides the laser L to its exit port and irradiates a predetermined position on the workpiece 61. The transmission optical system 51 has a focusing optical system, although not shown, that focuses the laser L from the transmission optical fiber 40. The laser L emitted from the processing head 50 enters the workpiece 61. Figure 1 In the diagram, the dashed arrow between the output end of the transmission fiber 40 and the workpiece 61 indicates the situation where the laser L emitted from the output end of the transmission fiber 40 reaches the workpiece 61.

[0026] The machining worktable 60 is a worktable for placing the workpiece 61. Preferably, the machining worktable 60 has a fixing mechanism to fix the workpiece 61 so that the workpiece 61 does not move during machining.

[0027] The laser processing machine 1 moves the processing table 60 relative to the processing head 50, thereby causing the laser L and the workpiece 61 to move relative to each other. Alternatively, the laser processing machine 1 may move the laser L and the workpiece 61 relative to each other 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 L in the workpiece 61.

[0028] The control device 70 sends control signals to the laser oscillator 20, the numerical aperture variable device 30, the machining head 50, and the machining table 60 respectively, controlling their respective operations. The laser oscillator 20 outputs laser beams LA and LB according to the control signals. The numerical aperture variable device 30 operates according to the control signals, changing the incident numerical aperture of the laser beam L onto the transmission fiber 40. The machining head 50 operates according to the control signals. The machining table 60 operates according to the control signals. As described above, the control device 70 controls the laser oscillator 20, the numerical aperture variable device 30, the machining head 50, and the machining table 60 respectively. Furthermore, the processing unit of the control device 70 that controls the operation of the numerical aperture variable device 30 is a control device that operates the numerical aperture variable device 30 and can be considered as part of the numerical aperture variable device 30.

[0029] The control device 70, through the control of the numerical aperture variable device 30, changes the incident numerical aperture of the transmission optical fiber 40, thereby adjusting the exit numerical aperture of the transmission optical fiber 40. In other words, the numerical aperture variable device 30 and the control device 70 control the exit numerical aperture of the transmission optical fiber 40 by controlling the incident numerical aperture of the transmission optical fiber 40.

[0030] Next, the details of the numerical aperture variable device 30 will be explained. Figure 2 This is a diagram schematically illustrating an example of the structure of the numerical aperture variable device according to Embodiment 1. Figure 2 The diagram not only shows the numerical aperture variable device 30, but also the laser oscillator 20 and the transmission fiber 40. Additionally, in... Figure 2 The diagram illustrates how the numerical aperture variable device 30 alters the incident numerical aperture of the transmission fiber 40 by changing the spacing between the two laser beams LA from laser oscillator 20A and LB from laser oscillator 20B. If the travel direction of lasers LA and LB in laser oscillators 20A and 20B is set as the Z-axis, and two mutually perpendicular axes perpendicular to the Z-axis are set as the X-axis and Y-axis, then laser oscillators 20A and 20B are arranged along the Y-axis. Furthermore, laser oscillators 20A and 20B are configured symmetrically with respect to the line extending the optical axis of the transmission fiber 40, i.e., the extension line.

[0031] The numerical aperture variable device 30 includes: a beam spacing changing unit 31, which changes the spacing of multiple lasers LA and LB, i.e., the beam spacing; and a focusing optical system 33, which focuses the lasers LA and LB after the beam spacing is changed onto the incident end of the transmission optical fiber 40.

[0032] The beam spacing modification unit 31 has two or more beam spacing modification units when the beam characteristics of multiple lasers LA and LB are directional in the XY plane. Figure 2 In this example, the beam spacing changing unit 31 has two beam spacing changing units 32-1 and 32-2. Beam spacing changing unit 32-1 changes the beam spacing in a first direction perpendicular to the Z-axis. Beam spacing changing unit 32-2 changes the beam spacing in a second direction different from the first direction. The beam spacing changing unit 31 changes the beam spacing ΔP1-1 of the lasers LA and LB emitted from 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. Furthermore, the change in the spacing of the lasers LA and LB changes the position of the lasers LA and LB in the XY plane. Therefore, the beam spacing changing unit 31 can also be referred to as a device for changing the arrangement of multiple lasers LA and LB in the XY plane.

[0033] The focusing optical system 33 focuses the laser beams LA and LB, whose beam spacing has been changed by the beam spacing changing section 31, onto the transmission optical fiber 40. The focusing optical system 33 includes one or more lenses. Figure 2 The example shown illustrates a condensing optical system 33 with one lens, but it can also have two or more lenses. Furthermore, when the condensing optical system 33 has two or more lenses, the incident numerical aperture NA_in of the directed transmission fiber 40 can also be changed within the condensing optical system 33.

[0034] 40 fiber optic cables for transmission Figure 2 As shown, the fiber has a core 41 and a cladding 42 made of a material with a lower refractive index than the core 41, which covers the periphery of the core 41. The laser L, focused at the incident end of the transmission fiber 40, travels through total internal reflection along the path shown by the dashed line and exits from the exit end with an exit numerical aperture NA_out, which is determined corresponding to the incident numerical aperture NA_in.

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

[0036] The beam spacing adjustment unit 32-1 includes a beam reconfiguration section 321-1 and a light-shielding member 326-1. The beam reconfiguration section 321-1 is composed of two planar transmitting plates 322-1 and 323-1 that allow laser beams LA and LB to pass through. The two transmitting plates 322-1 and 323-1 of the beam reconfiguration section 321-1 are rectangular plate-shaped planar substrates with the same dimensions. The two transmitting plates 322-1 and 323-1 are arranged at a predetermined interval in the Y-axis direction. A rotation axis (not shown) is provided at the center of the ZX plane of the transmitting plate 322-1, and a rotation mechanism (not shown) is provided on the rotation axis. As a result, the transmitting plate 322-1 rotates around the rotation axis (not shown). A rotation axis 325-1 is provided at the center of the ZX plane of the transmitting plate 323-1, and a rotation mechanism (not shown) is provided on the rotation axis 325-1. Therefore, the through plate 323-1 rotates around the rotation axis 325-1. Using a straight line A1 parallel to the X-axis and passing through the rotation axis 325-1 as a reference, the two through plates 322-1 and 323-1 are tilted in opposite directions at the same angle θ1. If the clockwise rotation direction from the straight line A1 is set as positive, and the counterclockwise rotation direction as negative, then... Figure 3In this example, the transmission plate 322-1 is tilted at an angle θ1, and the transmission plate 323-1 is 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 fiber 40. The rotation mechanism rotates the two transmission plates 322-1 and 323-1 respectively according to the instructions from the control device 70.

[0037] The light-shielding component 326-1 is disposed on the extension line of the optical axis of the transmission fiber 40 to block the reflected laser light traveling from the transmission fiber 40 towards the laser oscillators 20A and 20B. That is, the light-shielding component 326-1 is configured to suppress the reflected laser light reflected from the workpiece 61 from returning to the laser oscillator 20. Figure 3 In the example, the light-shielding component 326-1 is disposed between two transparent plates 322-1 and 323-1 and has a shape that extends in the X-axis direction.

[0038] The beam spacing adjustment unit 32-2 includes a beam reconfiguration section 321-2 and a light-shielding member 326-2. The beam reconfiguration section 321-2 is composed of two planar transmitting plates 322-2 and 323-2 that allow laser beams LA and LB to pass through. The two transmitting plates 322-2 and 323-2 of the beam reconfiguration section 321-2 are rectangular plate-shaped planar substrates with the same dimensions. The two transmitting 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 transmitting plate 322-2, and a rotation mechanism (not shown) is provided on the rotation axis 324-2. Thus, the transmitting 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 transmitting plate 323-2, and a rotation mechanism (not shown) is provided on the rotation axis 325-2. Therefore, the transmission plate 323-2 rotates around the rotation axis 325-2. Using a straight line parallel to the Y-axis passing through the rotation axes 324-2 and 325-2 as a reference, the two transmission plates 322-2 and 323-2 are tilted in opposite directions at the same angle. The two transmission plates 322-2 and 323-2 are symmetrically arranged with respect to the optical axis of the transmission fiber 40. The rotation mechanism rotates the two transmission plates 322-2 and 323-2 respectively according to the instructions from the control device 70.

[0039] The light-shielding component 326-2 is disposed on the extension line of the optical axis of the transmission optical fiber 40 to block reflected laser light from the transmission optical fiber 40 toward the laser oscillators 20A and 20B. That is, the light-shielding component 326-2 is configured to suppress reflected laser light from the workpiece 61 from returning to the laser oscillator 20. In one example, the light-shielding component 326-2 is disposed between two transmissive plates 322-2 and 323-2, and can be configured to extend in the Y-axis direction.

[0040] The transparent plates 322-1, 322-2, 323-1, and 323-2 are preferably optically isotropic materials that are transparent to the wavelengths of the lasers LA and LB oscillating from the laser oscillator 20. In the case where the laser oscillators 20A and 20B are fiber lasers that oscillate lasers LA and LB around 1070 nm, an example of the transparent plates 322-1, 322-2, 323-1, and 323-2 is a glass substrate such as synthetic quartz.

[0041] Light-shielding components 326-1 and 326-2 are respectively provided for multiple beam spacing changing units 32-1 and 32-2, and are located on the transmission optical fiber 40 side of each beam spacing changing unit 32-1 and 32-2. Light shielding in light-shielding components 326-1 and 326-2 only requires reflection or absorption of the laser. The material used for light-shielding components 326-1 and 326-2 depends on the wavelength of the laser L emitted by the laser oscillator 20. An example of light-shielding components 326-1 and 326-2 that provide light shielding through reflection is surface-treated copper. An example of light-shielding components 326-1 and 326-2 that provide light shielding through absorption is aluminum treated with an alumina film. Furthermore, light-shielding components 326-1 and 326-2 may have a cooling mechanism. The cooling mechanism includes piping located inside or in contact with the light-shielding members 326-1 and 326-2, and a refrigerant supply section to which refrigerant flows. An example of refrigerant is water. By directing water from the refrigerant supply section to the piping, the temperature rise of the light-shielding members 326-1 and 326-2 is suppressed.

[0042] A light-shielding component 326-1 is disposed between two transmitting plates 322-1 and 323-1, and a light-shielding component 326-2 is disposed between two transmitting plates 322-2 and 323-2. Therefore, within the numerical aperture variable device 30, at least one of the dimensions and arrangement of the light-shielding components 326-1 and 326-2 is determined such that, when the spatial distribution or spatial position of the incident lasers LA and LB is made closest, the output loss of the multiple lasers LA and LB caused by obstruction in the light-shielding components 326-1 and 326-2 is less than or equal to 10%. Therefore, Figure 3 The shapes of the light-shielding components 326-1 and 326-2 shown are one example, but other shapes are also possible.

[0043] Lasers LA and LB exhibit parabolic beam intensities. That is, they have a Gaussian distribution with high beam intensity at the center and decreasing towards the periphery. In this case, the beam intensity decreases from the peak position at a rate of 1 / e 2The beam width at the reduced point is defined as the Gaussian beam diameter. Using this Gaussian beam diameter, the portion of the laser LA and LB that deviates from the Gaussian beam diameter is approximately 10% of the laser LA and LB's beam diameter. Within the laser LA and LB, if the portion of the Gaussian beam diameter is considered to pass through, as described above, it is preferable to set the output loss caused by obstruction in the light-shielding components 326-1 and 326-2 to be less than or equal to 10%. Furthermore, the optical components constituting the laser processing machine 1 are generally designed optically using the Gaussian beam diameter. Therefore, it is also preferable to design the laser LA and LB such that the output loss caused by obstruction in the light-shielding components 326-1 and 326-2 is less than or equal to 10%.

[0044] Here, the method for adjusting the beam spacing in the numerical aperture variable device 30 will be explained. Figure 4 This is a diagram schematically illustrating an example of a method for changing the numerical aperture in the numerical aperture variable device according to Embodiment 1. Figure 4 Only the middle part is shown Figure 2 The beam spacing changing units 32-1 and 32-2 of the numerical aperture variable device 30. Additionally, in Figure 4 For convenience, the side view of the ZX plane (viewed from the Y-axis) and the side view of the YZ plane (viewed from the X-axis) are shown simultaneously.

[0045] exist Figure 4 In the beam spacing changing section 31 of the numerical aperture variable device 30, beam spacing changing unit 32-1 is disposed on the laser oscillator 20 side, and beam spacing changing unit 32-2 is disposed on the transmission fiber 40 side. Beam spacing changing unit 32-1 changes the beam spacing in the X-axis direction instead of the Y-axis direction, and beam spacing changing unit 32-2 changes the beam spacing in the Y-axis direction instead of the X-axis direction. Furthermore, as an example, beam spacing changing unit 32-1 and beam spacing changing unit 32-2 can simply change the beam spacing in any direction that is different from each other.

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

[0047] Laser oscillators 20A and 20B are spaced apart in the Y-axis direction and symmetrically arranged relative to the optical axis of the transmission fiber 40. Lasers LA and LB are output from laser oscillators 20A and 20B, respectively. The beam spacing of lasers LA and LB in the X-axis direction is set to ΔP1-1x, and the beam spacing in the Y-axis direction is set to ΔP1-1y.

[0048] Figure 5 It means Figure 4 A diagram illustrating an example of the changes in the configuration state of a laser within the XY plane. Here, it is shown... Figure 4 The lasers LA and LB are configured at positions R1, R2, and R3 in the optical path of the lasers in a plane perpendicular to the travel direction of the lasers LA and LB. Before being injected into the beam spacing changing unit 32-1, as shown in configuration state C1 at position R1, the lasers LA and LB are configured with a gap in the Y-axis direction. In addition, the lasers LA and LB have a flattened beam shape in the X-axis direction, that is, an elliptical beam shape with a longer diameter in the Y-axis direction compared to the X-axis direction. Moreover, the lasers LA and LB are injected into the beam spacing changing unit 32-1 in configuration state C1.

[0049] Return to Figure 4 In the beam spacing adjustment unit 32-1, two transmission plates 322-1 and 323-1 are arranged spaced apart in the Y-axis direction, and rotation axes 324-1 and 325-1 are parallel to the Y-axis. Here, transmission plate 322-1 is configured to allow laser LA from laser oscillator 20A to pass through, and transmission plate 323-1 is configured to allow laser LB from laser oscillator 20B to pass through. Furthermore, in the beam spacing adjustment unit 32-1, the two transmission plates 322-1 and 323-1 can rotate around the Y-axis. Here, as described above, with line A1 as a reference, transmission plate 322-1 is tilted at an angle θ1, and transmission plate 323-1 is tilted at an angle -θ1. By arranging the beam reconfiguration unit 321-1 as described above, the beam spacing in the X-axis direction can be changed.

[0050] Lasers LA and LB are incident on beam spacing changing unit 32-1. Here, laser LA is incident on transmitting plate 322-1, and laser LB is incident on transmitting plate 323-1. Lasers LA and LB are refracted when they are incident on transmitting plates 322-1 and 323-1. It appears that lasers LA and LB refract in the direction with an incident angle, i.e., in the ZX plane, and travel straight in the direction without an incident angle, i.e., in the YZ plane. In addition, the two transmitting plates 322-1 and 323-1 are tilted in opposite directions with the same angle θ1 relative to the straight line A1. Thus, in the ZX plane, the two lasers LA and LB refract in the direction of separation. On the other hand, in the YZ plane, lasers LA and LB do not refract. Parts of lasers LA and LB will touch the light-shielding member 326-1, but in the ZX plane, laser LA passes through the far end of the light-shielding member 326-1 in the Y-axis direction, and laser LB passes through the near end of the light-shielding member 326-1 in the Y-axis direction.

[0051] The configuration states of the laser LA and LB output from the beam spacing changing unit 32-1 become... Figure 5 The configuration state C2 is located at position R2. The dashed ellipse in configuration state C2 indicates the positions of lasers LA and LB in configuration state C1. For example... Figure 5 As shown, lasers LA and LB move in opposite directions along the X-axis at the same distance.

[0052] Return to Figure 4 The beam spacing in the X-axis direction of the lasers LA and LB output from the beam spacing modification unit 32-1 is set to ΔP1-2x, and the beam spacing in the Y-axis direction is set to ΔP1-2y. Figure 4 In the example, the beam spacing ΔP1-2x of the lasers LA and LB in the X-axis direction output from the beam spacing changing unit 32-1 is larger than the beam spacing ΔP1-1x before injection. On the other hand, the beam spacing ΔP1-2y of the lasers LA and LB in the Y-axis direction output from the beam reconfiguration unit 321-1 is equal to the beam spacing ΔP1-1y before injection.

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

[0054] As described above, two lasers LA and LB are incident on the beam spacing changing unit 32-2. Here, laser LA is incident on the transmitting plate 322-2, and laser LB is incident on the transmitting plate 323-2. Lasers LA and LB will be refracted if they are incident on the transmitting plates 322-2 and 323-2. Similar to the beam spacing changing unit 32-1, it appears that lasers LA and LB are refracted in the direction with the angle of incidence, i.e., in the YZ plane, and travel straight in the direction without the angle of incidence, i.e., in the ZX plane. In addition, the two transmitting plates 322-2 and 323-2 are tilted in opposite directions with the same angle θ2 relative to the straight line A2. Thus, lasers LA and LB do not refract in the ZX plane. On the other hand, in the YZ plane, the two lasers LA and LB are refracted in a direction closer together. Part of lasers LA and LB will hit the light-shielding member 326-2, but in the YZ plane, laser LA passes through the far end of the light-shielding member 326-2, and laser LB passes through the near end of the light-shielding member 326-2. Therefore, the beam spacing of the two lasers LA and LB output from the beam spacing changing unit 32-2 becomes ΔP2-2x in the X-axis direction and ΔP2-2y in the Y-axis direction. Figure 4 In the example, the beam spacing ΔP2-2x is equal to the beam spacing ΔP2-1x in the X-axis direction of the two lasers LA and LB before they are injected into the beam spacing adjustment unit 32-2. On the other hand, the beam spacing ΔP2-2y is smaller than the beam spacing ΔP2-1y in the Y-axis direction of the two lasers LA and LB before they are injected into the beam spacing adjustment unit 32-2.

[0055] The configuration states of the laser LA and LB output from the beam spacing changing unit 32-2 become... Figure 5 The configuration state C3 is located at position R3. The dashed ellipse under configuration state C3 indicates the positions of lasers LA and LB under configuration state C2. For example... Figure 5 As shown, lasers LA and LB move in opposite directions along the Y-axis and are located on the X-axis by the same distance.

[0056] As described above, as shown in configuration state C1, two elliptical lasers LA and LB, which are spaced apart in the Y-axis direction and extend in the Y-axis direction, are spaced apart in the X-axis direction via two beam spacing changing units 32-1 and 32-2, as shown in configuration state C3. That is, the lasers LA and LB can be reconfigured by the two beam spacing changing units 32-1 and 32-2.

[0057] When the beam quality of lasers LA and LB differs in the X-axis and Y-axis directions, the beam diameter and divergence angle of laser L can be changed by reconfiguring lasers LA and LB as described above.

[0058] Beam quality is known and can be represented by the product of the beam diameter and the divergence angle. The smaller the value calculated above, the better the quality of the laser LA and LB.

[0059] Regarding the beam diameter of a single laser, it can be determined as described above using the Gaussian beam diameter. On the other hand, regarding the beam diameter when multiple lasers (LA and LB) are coupled, a beam diameter determined by the energy distribution formed by the multiple LA and LB can be used. Various definitions exist for beam diameter, but here, the diameter containing a predetermined proportion of energy within the laser's energy range is considered the beam diameter. The beam diameter of multiple lasers (LA and LB) coupled as described above varies depending on the configuration of the multiple LA and LB. Furthermore, as a result, the beam quality changes.

[0060] For Figure 5 The case of multiple laser LA and LB coupling in configuration state C1 (two laser LA and LB coupled in the Y-axis direction) is compared with the case of multiple laser LA and LB coupling in configuration state C3 (two laser LA and LB coupled in the X-axis direction). In configuration state C1, the two flattened elliptical laser LA and LB are spaced apart in the Y-axis direction; in configuration state C3, they are also spaced apart in the X-axis direction. The beam diameter in the Y-axis direction of the laser LA and LB is larger than the beam diameter in the X-axis direction; therefore, the beam quality in the Y-axis direction is considered worse than that in the X-axis direction. Furthermore, considering the beam diameter as representing a predetermined proportion of the overall energy, the narrower the spacing between the two laser LA and LB, the smaller the beam diameter becomes. Taking all these factors into account, configuration state C3, with the laser LA and LB spaced apart in the Y-axis direction, is considered to have better beam quality than configuration state C1. Therefore, in... Figure 4 In this process, two beam spacing change units 32-1 and 32-2 are used to reconfigure the two lasers LA and LB so that they change from configuration state C1 to configuration state C3.

[0061] Furthermore, the beam spacing changing unit 32-1 and beam spacing changing unit 32-2 change the beam spacing in different directions, and the tilt angle can also be arbitrarily set. As described above, the shapes of the lasers LA and LB in the XY plane have directionality in the X and Y axes. Therefore, based on this shape, the displacement of the beam position in the X and Y axes is set so that the numerical aperture of the laser L after coupling multiple lasers LA and LB is approximately equal in the X and Y axes. The reason why the numerical aperture of the laser L is approximately equal in the X and Y axes is that the outgoing numerical aperture NA_out of the transmission fiber 40 depends on the larger of the incident numerical aperture NA_in.

[0062] The relationship between the tilt angles of the transmission plates 322-1, 322-2, 323-1, and 323-2 and the beam spacing was determined experimentally beforehand. Therefore, the tilt angles of the transmission plates 322-1, 322-2, 323-1, and 323-2 can be determined in such a way that the beam quality when the two lasers LA and LB output from the beam spacing adjustment unit 32-2 are coupled is the desired value.

[0063] Based on the above considerations regarding beam quality, the best beam quality can be obtained by overlapping multiple lasers LA and LB in a consistent manner. However, the reflected laser from the workpiece 61, emitted by the laser L from the processing head 50, sometimes returns to the laser oscillator 20 side in a distribution centered on the optical axis of the transmission fiber 40. As described above, in Embodiment 1, light-shielding members 326-1 and 326-2 are arranged at positions corresponding to the optical axes of the transmission fibers 40 on the output side of the lasers LA and LB in each beam spacing changing unit 32-1 and 32-2. By arranging the light-shielding members 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 spacing between two lasers LA and LB. With the light-shielding members 326-1 and 326-2 present, the beam spacing that minimizes the beam quality of the two lasers LA and LB is determined. If two laser beams LA and LB with a beam spacing that minimizes beam quality are incident on the incident end of the transmission fiber 40 via the focusing optical system 33, then the light-receiving angle of the transmission fiber 40 becomes minimum. That is, the incident numerical aperture NA_in of the transmission fiber 40 becomes minimum.

[0064] Furthermore, to minimize the beam quality of the two lasers LA and LB, the multiple lasers LA and LB must be symmetrically arranged relative to the extension of the optical axis of the transmission fiber 40. This is because if the two lasers LA and LB are not symmetrical with respect to the extension of the optical axis of the transmission fiber 40, the incident angle of one laser within the two lasers LA and LB becomes larger compared to the other. The outgoing numerical aperture NA_out of the transmission fiber 40 depends on a large incident numerical aperture NA_in; therefore, to reduce the outgoing numerical aperture NA_out of the transmission fiber 40, the incident numerical aperture NA_in of the transmission fiber 40 needs to be reduced. To minimize the incident numerical aperture NA_in of the transmission fiber 40 as much as possible, the laser needs to be incident along the extension of the optical axis of the transmission fiber 40. Furthermore, when two lasers LA and LB are configured, the incident numerical aperture NA_in of the transmission fiber 40 is minimized so that the output loss of the lasers LA and LB caused by the obstruction in the light-shielding components 326-1 and 326-2 is less than or equal to 10%, and the two lasers LA and LB that are spatially closest in distribution or spatial position are symmetrical with respect to the extension line of the optical axis of the transmission fiber 40.

[0065] As mentioned above, not all laser light L incident on the transmission fiber 40 is transmitted via total internal reflection. Only laser light L incident at an angle less than or equal to the maximum value of the reception angle of the transmission fiber 40 is transmitted via total internal reflection. Laser light L incident at an angle greater than the maximum value of the reception angle of the transmission fiber 40 cannot be transmitted through the transmission fiber 40 and becomes emitted light, resulting in loss. At the maximum value of the reception angle of the transmission fiber 40, the incident numerical aperture NA_in of the transmission fiber 40 becomes maximum.

[0066] As described above, the numerical aperture variable device 30 adjusts the rotation angles of the transmission plates 322-1, 322-2, 323-1, and 323-2 of the beam spacing changing units 32-1 and 32-2, thereby enabling the incident numerical aperture NA_in of the transmission fiber 40 to be variable between its minimum and maximum values. That is, if the condition converges to the minimum and maximum values ​​of the incident numerical aperture, adjusting the rotation angles of the transmission plates 322-1, 322-2, 323-1, and 323-2 allows for the modification of the beam quality of the laser L after coupling multiple lasers LA and LB, more specifically, the beam diameter or divergence angle.

[0067] At this time, the operation of beam spacing changing units 32-1 and 32-2 can also be restricted so that the incident numerical aperture NA_in is not greater than the maximum value of the incident numerical aperture of the transmission fiber 40.

[0068] In addition, such as Figure 2As shown, the outgoing numerical aperture NA_out at the outgoing end of the transmission fiber 40 changes in accordance with the incident numerical aperture NA_in at the incident end. That is, the outgoing numerical aperture NA_out of the transmission fiber 40 can be changed in the same way as the incident numerical aperture NA_in. As described above, in Embodiment 1, the incident numerical aperture NA_in can be significantly varied from the aforementioned minimum to the maximum value by means of the numerical aperture variable device 30; therefore, the variable range of the outgoing numerical aperture NA_out can also be significantly varied in accordance with the incident numerical aperture NA_in.

[0069] Furthermore, the above description shows the numerical aperture variable device 30 having two beam spacing adjustment units 32-1 and 32-2, but this is merely an example. When the beam characteristics of the lasers LA and LB emitted from the laser oscillators 20A and 20B differ in the X-axis and Y-axis directions, the numerical aperture variable device 30 may have two or more beam spacing adjustment units. However, when the beam characteristics of the lasers LA and LB emitted from the laser oscillators 20A and 20B are not directional in the X-axis and Y-axis directions, there may be only one beam spacing adjustment unit. Additionally, the rotation axes 324-1 and 325-1 of the beam spacing adjustment unit 32-1 and the rotation axes 324-2 and 325-2 of the beam spacing adjustment unit 32-2 are perpendicular to each other, but this is also just an example. If 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 the optical axis of the transmission fiber 40, and the directions of their rotation axes 324-1, 324-2, 325-1 and 325-2 are not the same, then they can be any direction.

[0070] Furthermore, the rotational positions of the beam reconfiguration units 321-1 and 321-2, i.e. the tilt angles of the transmission plates 322-1, 322-2, 323-1, and 323-2, can be arbitrarily controlled, or they can be configured to have a preset angle stored in advance, and rotate to the preset angle by means of instructions from the control device 70.

[0071] The numerical aperture variable device 30 of Embodiment 1 has multiple beam spacing changing units 32-1 and 32-2, which reconfigure multiple lasers LA and LB, changing the incident numerical aperture NA_in of the transmission fiber 40 when the reconfigured multiple lasers LA and LB are focused and incident on the transmission fiber 40. Each of the multiple beam spacing changing units 32-1 and 32-2 has light-shielding members 326-1 and 326-2, which are provided on the transmission fiber 40 side, in the region including the extension line of the optical axis of the transmission fiber 40. As a result, reflected laser light reflected by the workpiece 61 and returning to the laser oscillator 20 side in a distribution centered on the optical axis of the transmission fiber 40 can be blocked, preventing it from passing through the laser oscillator 20 side. That is, the outgoing numerical aperture NA_out of the transmission fiber 40 can be controlled while suppressing the laser oscillator 20 from malfunctioning due to reflected laser light. In addition, even when there is a lot of reflected laser light reflected by the workpiece 61, the laser oscillator 20 will not malfunction and can still operate.

[0072] Furthermore, the beam spacing adjustment unit 32-1 includes: two transmission plates 322-1 and 323-1, which are rotatable about rotation axes 324-1 and 325-1; and a rotation mechanism that drives each transmission plate 322-1 and 323-1 about rotation axes 324-1 and 325-1 to achieve an arbitrary tilt angle. The beam spacing adjustment unit 32-2 includes: two transmission plates 322-2 and 323-2, which are rotatable about rotation axes 324-2 and 325-2; and a rotation mechanism that drives each transmission plate 322-2 and 323-2 about rotation axes 324-2 and 325-2 to achieve an arbitrary tilt angle. Additionally, the laser processing machine 1 includes a control device 70 that controls the tilt angle 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 spacing of lasers LA and LB by setting the tilt angles of the two transmission plates 322-1 and 323-1 of the beam spacing changing unit 32-1 and the two transmission plates 322-2 and 323-2 of the beam spacing changing unit 32-2 to a predetermined angle. That is, it can control the incident numerical aperture NA_in of the transmission fiber 40 between its minimum and maximum values. Furthermore, by increasing the variable range of the incident numerical aperture NA_in, the variable range of the exit numerical aperture NA_out of the transmission fiber 40 can also be increased.

[0073] Furthermore, the multiple lasers LA and LB are configured symmetrically with respect to the extension of the optical axis of the transmission fiber 40. Specifically, the laser oscillators 20A and 20B, the transmission plates 322-1 and 323-1 of the beam spacing adjustment unit 32-1, and the transmission plates 322-2 and 323-2 of the beam spacing adjustment unit 32-2 are configured symmetrically with respect to the extension of the optical axis of the transmission fiber 40. This allows the beam quality of the laser L, including the multiple lasers LA and LB, to be set symmetrically. Additionally, even if the beam quality of multiple lasers LA and LB is not good, the lasers LA and LB can be reconfigured to improve the beam quality.

[0074] In one example, the aforementioned control device 70 is implemented via a processing circuit, i.e., a circuit that executes software via a processor. In one example, the processing circuit that executes the software is... Figure 6 The control circuit shown. Figure 6 This is a diagram illustrating an example of the hardware structure of the control device for the laser processing machine according to Embodiment 1. The 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 outside the control circuit 100 and provides it to the processor 102. The output unit 104 is an interface circuit that transmits data from the processor 102 or the memory 103 to outside the control circuit 100. In the processing circuit... Figure 6 In the case of the control circuit 100 shown, the aforementioned structural elements are realized by reading and executing the program stored in the memory 103 that controls the laser oscillator 20, the numerical aperture variable device 30, the machining head 50, and the machining table 60. The memory 103 is also used as temporary memory in each process implemented by the processor 102. The processor 102 can output data such as calculation results to the memory 103 for storage, or it can store the calculation results and other data in an auxiliary storage device via the volatile memory of the memory 103.

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

[0077] Figure 6 This is an example of hardware implementing the control device 70 using a general-purpose processor 102 and memory 103, but the control device 70 can also be implemented using dedicated hardware circuitry. Dedicated hardware circuitry, i.e., processing circuitry, can be a single circuit, a composite circuit, a programmable processor, a parallel-programmable processor, an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), or a combination thereof. The aforementioned structural elements can be implemented through a combination of control circuitry 100 and dedicated hardware circuitry.

[0078] The structure shown in the above implementation is an example and can also be combined with other known technologies. Without departing from the main idea, parts of the structure can be omitted or modified.

[0079] Explanation of the label

[0080] 1. Laser processing machine; 10. Laser device; 20, 20A, 20B laser oscillators; 30. Numerical aperture variable device; 31. Beam spacing change unit; 32-1, 32-2. Beam spacing change unit; 33. Focusing optical system; 40. Transmission fiber; 41. Fiber 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. Transmitting plates; 324-1, 324-2, 325-1, 325-2. Rotating shafts; 326-1, 326-2. Shielding components; A1, A2. Linear lasers; L, LA, LB lasers.

Claims

1. A numerical aperture variable device which reconfigures a spatial distribution or a spatial position of a plurality of lasers emitted from a laser oscillator, and condenses the reconfigured plurality of lasers to be emitted to a delivery fiber, the numerical aperture variable device characterized by having a light shielding member which is provided on an extension line of an optical axis of the delivery fiber, and shields reflected laser light which is laser light emitted from the delivery fiber toward the laser oscillator.

2. The numerical aperture variable device according to claim 1, characterized in that the light shielding member has, inside the numerical aperture variable device, a size which, when the spatial distribution or the spatial position of the emitted plurality of lasers is closest, causes an output loss of the plurality of lasers to be less than or equal to 10%.

3. The numerical aperture variable device according to claim 1, characterized in that the light shielding member is configured, inside the numerical aperture variable device, to cause an output loss of the plurality of lasers to be less than or equal to 10% when the spatial distribution or the spatial position of the emitted plurality of lasers is closest.

4. The numerical aperture variable device according to claim 1, characterized in that the light shielding member is composed of a material which absorbs or reflects the reflected laser light.

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

6. The numerical aperture variable device according to claim 1, characterized in that there are a plurality of beam interval changing units which change a beam interval of the emitted plurality of lasers, the light shielding member is provided for each of the plurality of beam interval changing units, and is located on the delivery fiber side of the beam interval changing unit.

7. The numerical aperture variable device according to claim 6, characterized in that there is further a control device which controls an operation of the plurality of beam interval changing units, each of the plurality of beam interval changing units has: a beam reconfiguring section in which a plurality of transmission plates which transmit the laser light are arranged at a prescribed interval; and a rotation mechanism which rotates the plurality of transmission plates respectively around a rotation axis, the control device controls the rotation mechanism so that an incident angle of the plurality of lasers to the plurality of transmission plates becomes a prescribed angle.

8. The numerical aperture variable device according to claim 7, characterized in that the plurality of lasers are symmetrically emitted in the numerical aperture variable device with respect to an extension line of an optical axis of the delivery fiber, the plurality of transmission plates are symmetrically arranged with respect to the extension line of the optical axis of the delivery fiber.

9. A laser device, characterized by having: the numerical aperture variable device described in any one of claims 1 to 8; and the laser oscillator which emits the plurality of lasers to the numerical aperture variable device.

10. A laser processing machine characterized by comprising: having: the laser device described in claim 9; a delivery fiber which transmits the plurality of lasers from the laser device; and a processing head which irradiates the plurality of lasers from the delivery fiber to a processed object. having: the laser device described in claim 9; a delivery fiber which transmits the plurality of lasers from the laser device; and a processing head which irradiates the plurality of lasers from the delivery fiber to a processed object.

Images