Device for changing the numerical aperture, laser device and laser beam machine

Abstract

Device (30) for changing the numerical aperture for realigning spatial distributions or spatial positions of several laser beams (LA, LB) incident from a laser oscillator (20) and propagating in the direction of an axis (Z), and for condensing the several realigned laser beams for entry of the beams into a transmission fiber (40), wherein the device for changing the numerical aperture is characterized by: a light-shielding component (326-1, 326-2) provided in an extension of the optical axis of the transmission fiber (40), wherein the light-shielding component (326-1, 326-2) blocks a reflected laser beam, the reflected laser beam being a laser beam traveling from the transmission fiber (40) to the laser oscillator (20); and Several beam spacing change units (32-1, 32-2) for changing beam spacings between the several incident laser beams (LA, LB) in two different directions (X, Y), wherein one of the several beam spacing change units (32-1) is configured to change a beam spacing in a first direction (X) perpendicular to the axis (Z), and another of the several beam spacing change units (32-2) is configured to change a beam spacing in a second direction (Y) different from the first direction (X), wherein for each of the multiple beam spacing change units (32-1, 32-2) a light shielding component (326-1, 326-2) is provided, and each of the light shielding components (326-1, 326-2) is arranged on one side closer to the transmission fiber (40) with respect to the corresponding beam spacing change unit (32-1, 32-2).

Description

Area

[0001] The present disclosure relates to a device for changing the numerical aperture, a laser device and a laser beam machine that changes a numerical aperture of a transmission fiber. State of the art

[0002] A laser beam machine generally comprises a laser oscillator, a condenser lens (or condenser), a transmission fiber, and a processing head. The condenser lens condenses (collects) a laser beam emitted by the laser oscillator. The transmission fiber carries the laser beam condensed by the condenser lens. The processing head directs the laser beam from the transmission fiber to a desired location on a workpiece. Among such laser beam machines, one known design uses multiple laser beams entering a single transmission fiber for the purpose of achieving a higher output.

[0003] Document 1 discloses a beam parameter matching system that modifies the spatial distribution of multiple beams with a single polarization state and a collective spatial distribution from a beam source, and converges the beams with the modified spatial distribution onto an end face of a transmission fiber. In the technology described in Document 1, the respective polarization state of the multiple beams is changed. As a result, the spatial distribution of the beams entering the transmission fiber is modified to match the parameter product of an output beam from the transmission fiber.

[0004] Document 2 discloses a beam parameter setting system and focusing system for changing a spatial power distribution of a plurality of beam bundles before coupling them into an optical fiber. List of citations from patent literature Publication 1: WO 2015 / 130 920 A1 Publication 2: DE 11 2015 000 994 T5 Brief description of the invention; Problem to be solved by the invention

[0005] In a case where the technology described in Publication 1 is applied to a laser beam machine that includes a transmission fiber with the same axis of incidence as an axis of an incident laser beam at one side of the beam-emitting source, a laser beam reflected from a workpiece unfortunately returns to a laser oscillator serving as the beam-emitting source because the reflected laser beam is distributed centrally on the axis of incidence of the transmission fiber. This poses a problem of damage to the laser oscillator by the reflected laser beam.

[0006] The present disclosure was made in view of the above, and it is the object of the present disclosure to provide a device for changing the numerical aperture which is capable of protecting a laser oscillator from damage by a reflected laser beam returning in a central distribution around an incidence axis of a transmission fiber. Means of solving the problem

[0007] To solve the problem and fulfill the objective, the present disclosure provides a device according to claim 1 for changing the numerical aperture, namely for realigning the spatial distributions or spatial arrangements of several laser beams incident from a laser oscillator, and for condensing the several realigned laser beams for entry of the beams into a transmission fiber, wherein the device for changing the numerical aperture comprises: A light-shielding component provided in an extension of the optical axis of the transmission fiber, wherein the light-shielding component blocks a reflected laser beam, wherein the reflected laser beam is a laser beam traveling from the transmission fiber to the laser oscillator. Effects of the invention

[0008] The device for changing the numerical aperture according to the present disclosure has the effect of preventing a laser oscillator from being damaged by a reflected laser beam that returns in a central distribution around an incidence axis of the transmission fiber. Brief description of the drawings Fig. Figure 1 is a diagram that schematically shows an exemplary configuration of a laser beam machine according to a first embodiment. Fig. Figure 2 is a diagram that schematically shows an exemplary configuration of a device for changing the numerical aperture according to a first embodiment. Fig. Figure 3 is a side view of a beam distance changer, which schematically shows an exemplary configuration of the beam distance changer in the device for changing the numerical aperture according to the first embodiment. Fig. Figure 4 is a diagram that schematically shows an exemplary method for changing the numerical aperture in the device for changing the numerical aperture according to the first embodiment. Fig. Figure 5 is a diagram that shows an example of changes in the state of the arrangement of laser beams in an XY plane. Fig. 4 shows. Fig. Figure 6 is a diagram showing an exemplary hardware configuration of a control unit of the laser beam machine according to the first embodiment. Description of the embodiments

[0009] A device for changing the numerical aperture, a laser device and a laser beam machine according to an embodiment of the present disclosure are described in more detail below with reference to the drawings. First embodiment.

[0010] Fig. Figure 1 is a diagram schematically showing an exemplary configuration of a laser beam machine according to a first embodiment. A laser beam machine 1 is a machine tool that processes a target object or a workpiece 61 by irradiating it with a laser beam L, which is a laser beam.

[0011] The laser beam machine 1 comprises a laser device 10, a transmission fiber 40, a processing head 50, a processing table 60, and a control unit 70. The laser device 10 emits a laser beam L. The transmission fiber 40 transmits the laser beam L. The processing head 50 irradiates the workpiece 61 with the laser beam L from the transmission fiber 40. The processing table holds the workpiece 61. The control unit 70 controls the entire laser beam machine 1.

[0012] The laser device 10 includes a laser oscillator 20 and a numerical aperture (NA) changing device 30. The laser oscillator 20 is a light source. The numerical aperture changing device 30 changes the numerical aperture upon entry into the transmission fiber 40.

[0013] The laser oscillator 20 is a light source that emits laser beams LA and LB, such as a solid-state laser, a gas laser, or a semiconductor laser. The laser oscillator 20 emits multiple laser beams LA and LB. A single laser oscillator 20 can emit multiple laser beams LA and LB. Alternatively, several laser oscillators 20 can each emit a corresponding laser beam LA and LB. The laser oscillator 20 is arranged such that the positions of the multiple laser beams LA and LB are symmetrical with respect to an extension of an optical axis of the transmission fiber 40. The laser oscillator 20 causes the multiple laser beams LA and LB to enter the device 30 for changing the numerical aperture.

[0014] The numerical aperture changing device 30 connects the laser oscillator 20 and the transmission fiber 40. The numerical aperture changing device 30 realigns or redetermines the spatial distributions or positions of the multiple laser beams LA and LB arriving from the laser oscillator 20 and condenses the multiple, thus realigned, LA and LB beams for entry into an input end of the transmission fiber 40. A laser beam obtained by condensing the multiple laser beams LA and LB and transmitted through the transmission fiber 40 is called the laser beam L. Numerical apertures represent a measure of an acceptance angle and an exit angle for the transmission fiber 40. The numerical aperture changing device 30 can also be described as a device that changes the numerical entry aperture and exit aperture of the transmission fiber 40.

[0015] The acceptance angle of the transmission fiber 40 has a maximum value. This maximum value denotes the maximum acceptance angle at which a laser beam can travel through the transmission fiber 40 in total internal reflection. In addition to the maximum acceptance angle described above, the numerical input aperture also has a minimum value. The minimum value is determined by the quality of a laser beam emitted by the laser oscillator 20 and the structure of the device 30 for changing the numerical aperture, as will be described below. The device 30 for changing the numerical aperture modifies the numerical input aperture such that the numerical input aperture lies between the minimum and maximum values. The numerical input aperture is changed by realigning or re-determining the spatial distributions or positions of the multiple laser beams LA and LB.An example of realigning multiple laser beams LA and LB is changing the beam spacing between them. Note that... Fig. Figure 1 schematically shows the device 30 for changing the numerical aperture. Fig. 1 The broken arrows shown between the laser oscillator 20 and the entry end of the transmission fiber 40 indicate how the laser beams LA and LB pass through the device 30 for changing the numerical aperture.

[0016] The input end of the transmission fiber 40 is connected to the laser device 10, specifically the device 30 for changing the numerical aperture. An output end of the transmission fiber 40 is connected to the processing head 50. The laser beam L, transmitted through the transmission fiber 40, enters the processing head 50. The transmission fiber 40, which is an optical waveguide that transmits the laser beam L, comprises a core and a cladding. The cladding covers a circumference of the core with a material having a lower refractive index than that of the core. This structure of the transmission fiber 40 allows the laser beam L to travel in total internal reflection, with a numerical input aperture equal to or less than the maximum value of the numerical input aperture of the transmission fiber 40.

[0017] The processing head 50 is connected to the laser device 10 via the transmission fiber 40 and irradiates the workpiece 61 with the laser beam L transmitted through the transmission fiber 40. The processing head 50 includes an optical transmission system 51 that guides the laser beam L to an emission port of the processing head 50. Thus, the processing head 50 directs the laser beam L to a predetermined location on the workpiece 61. Although not shown, the optical transmission system 51 includes a condensing optical system that condenses the laser beam L from the transmission fiber 40. The laser beam L emitted by the processing head 50 strikes the workpiece 61. Fig. Figure 1 shows a broken arrow between the exit end of the transmission fiber 40 and the workpiece 61, indicating how the laser beam L emitted from the exit end of the transmission fiber 40 reaches the workpiece 61.

[0018] The machining table 60 is a table on which the workpiece 61 is placed. The machining table 60 preferably has a clamping mechanism that secures the workpiece 61 so that it does not move during machining.

[0019] The laser beam machine 1 moves the laser beam L and the workpiece 61 relative to each other by moving the processing table 60 with respect to the processing head 50. Note that the laser beam machine 1 can move the laser beam L and the workpiece 61 relative to each other without moving the processing table 60. The laser beam machine 1 can fix the position of the processing table 60 and control the point of incidence of the laser beam L on the workpiece 61.

[0020] The control unit 70 transmits a control signal to each of the laser oscillator 20, the numerical aperture changing device 30, the processing head 50, and the processing table 60, and controls their operation. The laser oscillator 20 outputs the laser beams LA and LB according to the control signal. The numerical aperture changing device 30 operates according to the control signal to change the numerical input aperture of the transmission fiber 40 for the laser beam L. The processing head 50 operates according to the control signal. The processing table 60 operates according to the control signal. In this way, the control unit 70 controls each of the laser oscillator 20, the numerical aperture changing device 30, the processing head 50, and the processing table 60. Note that a processor unit of the control unit 70, which controls the operation of the numerical aperture changing device 30, is a control unit that causes the numerical aperture changing device 30 to operate.Thus, the processor unit can be considered part of the device 30 for changing the numerical aperture.

[0021] The control unit 70, which controls the device 30 for changing the numerical aperture to change the numerical input aperture of the transmission fiber 40, adjusts the numerical output aperture at the exit end of the transmission fiber 40. That is, the device 30 for changing the numerical aperture and the control unit 70 control the numerical input aperture of the transmission fiber 40 in order to thereby control the numerical output aperture of the transmission fiber 40.

[0022] Next, the device 30 for changing the numerical aperture will be described in more detail. Fig. Figure 2 is a diagram that schematically shows an exemplary configuration of a device for changing the numerical aperture according to the first embodiment. Fig. Figure 2 shows not only the device 30 for changing the numerical aperture, but also the laser oscillator 20 and the transmission fiber 40. Furthermore, it shows Fig. 2. A case in which the device 30 for changing the numerical aperture changes the numerical input aperture of the transmission fiber 40 by changing a distance between the two laser beams LA and LB, that is, the laser beam LA from a laser oscillator 20A and the laser beam LB from a laser oscillator 20B. Suppose a Z-axis direction is defined as the direction in which the laser beams LA and LB travel in the laser oscillators 20A and 20B, and two axes perpendicular to the Z-axis are defined as an X-axis and a Y-axis. In this case, the laser oscillators 20A and 20B are arranged side-by-side along a Y-axis direction. Furthermore, the laser oscillators 20A and 20B are arranged such that the laser oscillators 20A and 20B are symmetrical with respect to an extension which is an extended optical axis of the transmission fiber 40.

[0023] The device 30 for changing the numerical aperture includes a beam spacing changer 31 and a condensing optical system 33. The beam spacing changer 31 changes the beam spacing between the multiple laser beams LA and LB. The condensing optical system 33 focuses the laser beams LA and LB with the changed beam spacing into the entrance end of the transmission fiber 40.

[0024] In a case where the beam characteristics of the multiple laser beams LA and LB are aligned in an XY plane, the beam spacing modifier 31 includes two or more beam spacing modifier units 32-1 and 32-2. In the example of Fig. The beam spacing changer 31 comprises two beam spacing change units 32-1 and 32-2. Beam spacing change unit 32-1 changes a beam spacing in a first direction perpendicular to the Z-axis. Beam spacing change unit 32-2 changes a beam spacing in a second direction different from the first. The beam spacing changer 31 changes a beam spacing ΔP1-1 between the laser beams LA and LB emitted by the laser oscillators 20A and 20B, respectively, to a beam spacing ΔP2-2. In this case, the first direction corresponds to an X-axis direction, and the second direction corresponds to the Y-axis direction. Furthermore, changing the spacing between the laser beams LA and LB corresponds to changing the positions of the laser beams LA and LB in the XY plane. In other words, the beam spacing changer 31 is a device that changes the arrangement of the multiple laser beams LA and LB in the XY plane.

[0025] The condensing optical system 33 condenses the laser beams LA and LB with the beam spacing changed by the beam spacing changer 31, and causes the laser beams LA and LB to enter the transmission fiber 40. The condensing optical system 33 includes one or more lenses. In the example of Fig. 2 a single lens, but can contain two or more lenses. Note that in the case of an optical system 33 containing two or more lenses, the numerical input aperture NA_in of the transmission fiber 40 can also be changed by the condensing optical system 33.

[0026] As in Fig. As shown in Figure 2, the transmission fiber 40 comprises a core 41 and a sheath 42. The sheath 42 covers the circumference of the core 41 and is made of a material with a lower refractive index than that of the core. The laser beam L, concentrated at the inlet end of the transmission fiber 40, follows the paths indicated by dashed lines by total internal reflection and is emitted at the outlet end with a numerical output aperture NA_out, which is determined in relation to the numerical input aperture NA_in.

[0027] Fig. Figure 3 is a side view of the beam spacing changer, which schematically shows an exemplary configuration of the beam spacing changer in the device for changing the numerical aperture according to the first embodiment. As described above, the beam spacing changer 31 includes the beam spacing changer unit 32-1 and the beam spacing changer unit 32-2.

[0028] The beam spacing change unit 32-1 comprises a beam realignment unit 321-1 and a light shielding component 326-1. The beam realignment unit 321-1 includes a combination of two flat transmission plates 322-1 and 323-1, which transmit the laser beams LA and LB, respectively. The two transmission plates 322-1 and 323-1 of the beam realignment unit 321-1 are rectangular, plate-like, flat substrates of the same size. The two transmission plates 322-1 and 323-1 are arranged at a predetermined distance in the Y-axis direction. A rotating shaft (not shown) is arranged in the center of the transmission plate 322-1 in a ZX plane, and a rotation mechanism (not shown) is arranged on the rotating shaft. As a result, the transmission plate 322-1 rotates around the (not shown) rotating shaft.A rotating shaft 325-1 is arranged in the center of the transmission plate 323-1 in a ZX plane, and a rotation mechanism (not shown) is arranged on the rotating shaft 325-1. As a result, the transmission plate 323-1 rotates around the rotating shaft 325-1. The two transmission plates 322-1 and 323-1 are arranged such that they are inclined in opposite directions by the same angle θ1 with respect to a straight line A1. The straight line A1 passes through the rotating shaft 325-1 and is parallel to the X-axis. Assuming that a clockwise direction of rotation from the straight line A1 is defined as the positive direction and a counterclockwise direction of rotation is defined as the negative direction, the transmission plates 322-1 and 323-1 in the example shown are... Fig. 3 such that transmission plate 322-1 is inclined at an angle of θ1, and transmission plate 323-1 is inclined at an angle of -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 mechanisms rotate the respective transmission plates 322-1 and 323-1 according to an instruction from the control unit 70.

[0029] The light-shielding component 326-1 is a component arranged on the extension of the optical axis of the transmission fiber 40 and blocks a reflected laser beam traveling from the transmission fiber 40 to the laser oscillators 20A and 20B. That is, the light-shielding component 326-1 is arranged to prevent a laser beam reflected from the workpiece 61 from returning to the laser oscillator 20. In the example of Fig. 3 The light-shielding component 326-1 is arranged between the two transmission plates 322-1 and 323-1, and has a shape that extends in the X-axis direction.

[0030] The beam spacing change unit 32-2 comprises a beam realignment unit 321-2 and a light shielding component 326-2. The beam realignment unit 321-2 includes a combination of two flat transmission plates 322-2 and 323-2, which transmit the laser beams LA and LB, respectively. The two transmission plates 322-2 and 323-2 of the beam realignment unit 321-2 are rectangular, plate-like, flat substrates of the same size. The two transmission plates 322-2 and 323-2 are arranged at a predetermined distance in the X-axis direction. A rotating shaft 324-2 is arranged in the center of the transmission plate 322-2 in a YZ plane, and a rotation mechanism (not shown) is arranged on the rotating shaft 324-2. As a result, the transmission plate 322-2 rotates around the rotating shaft 324-2.A rotating shaft 325-2 is arranged in the center of the transmission plate 323-2 in the YZ plane, and a rotation mechanism (not shown) is arranged on the rotating shaft 325-2. As a result, the transmission plate 323-2 rotates around the rotating shaft 325-2. The two transmission plates 322-2 and 323-2 are arranged such that they are inclined at the same angle in opposite directions with respect to a straight line passing through the rotating shafts 324-2 and 325-2 parallel to the Y-axis. The two transmission plates 322-2 and 323-2 are arranged symmetrically with respect to the optical axis of the transmission fiber 40. The rotation mechanisms rotate each of the two transmission plates 322-2 and 323-2 according to an instruction from the control unit 70.

[0031] The light-shielding component 326-2 is a component arranged on the extension of the optical axis of the transmission fiber 40 and blocks a reflected laser beam traveling from the transmission fiber 40 to the laser oscillators 20A and 20B. That is, the light-shielding component 326-2 is arranged to prevent a laser beam reflected from the workpiece 61 from returning to the laser oscillator 20. In one example, the light-shielding component 326-2 can be arranged between the two transmission plates 322-2 and 323-2 and can have a shape extending in the Y-axis direction.

[0032] The transmission plates 322-1, 322-2, 323-1 and 323-2 are preferably made of an optically isotropic material that is transparent to the wavelengths of the laser beams 20A and 20B oscillated by the laser oscillator 20. In the case where the laser oscillators 20A and 20B are fiber lasers oscillating the laser beams LA and LB with wavelengths around 1070 nm, an example of a glass substrate for the transmission plates 322-1, 322-2, 323-1 and 323-2 is synthetic quartz.

[0033] The light-shielding components 326-1 and 326-2 are provided for the multiple beam spacing change units 32-1 and 32-2, respectively, and are arranged on sides closer to the transmission fiber 40 with respect to the beam spacing change units 32-1 and 32-2. The light-shielding components 326-1 and 326-2 only need to perform a certain degree of light shielding by reflecting or absorbing the laser beam. A material for use as the light-shielding components 326-1 and 326-2 depends on the wavelength of the laser beam L to be emitted by the laser oscillator 20. An example of a light-shielding component 326-1 and 326-2 for light shielding by reflection is surface-treated copper. An example of the light-shielding components 326-1 and 326-2 in the case of light shielding by absorption is aluminum that has undergone anodizing (alumite treatment).Furthermore, the light-shielding components 326-1 and 326-2 can each have a cooling mechanism. The cooling mechanisms include tubes and refrigerant supply units. The tubes are provided within or in contact with the light-shielding components 326-1 and 326-2. Each refrigerant supply unit allows a refrigerant to flow through the tube. An example of a refrigerant is water. The flow of water from the refrigerant supply units through the tubes will prevent an increase in temperature within the light-shielding components 326-1 and 326-2.

[0034] The light-shielding component 326-1 is arranged between the transmission plates 322-1 and 323-1, and the light-shielding component 326-2 is arranged between the transmission plates 322-2 and 323-2. Therefore, the size and / or arrangement of the light-shielding components 326-1 and 326-2 is determined such that the output loss due to the blocking of the multiple laser beams LA and LB at the light-shielding components 326-1 and 326-2 becomes 10% or less when the spatial distributions or spatial arrangements of the multiple laser beams LA and LB in the device 30 for changing the numerical aperture are brought closest to each other. Thus, the Fig. Figure 3 shows the shape of the light-shielding components 326-1 and 326-2 as an example, and the light-shielding components 326-1 and 326-2 may have other shapes.

[0035] The laser beams LA and LB each exhibit a curved beam intensity. That is, the laser beams LA and LB provide a Gaussian distribution, with the beam intensity being high in the center and decreasing towards the edges. In this case, the Gaussian beam diameter is defined as the beam width of a beam with a beam intensity that decreases from a peak by 1 / e 2is reduced. When this Gaussian beam diameter is used, the laser beams LA and LB have regions of approximately 10% outside the Gaussian beam diameter. Considering that the Gaussian beam diameter regions of the laser beams LA and LB pass through the transmission plates, it is desirable that the output loss caused by blocking at the light-shielding components 326-1 and 326-2, as described above, be limited to 10% or less. Furthermore, optical components of the laser beam machine 1 are generally designed with a Gaussian beam diameter in many cases. Therefore, it is desirable to design the optical components such that the output loss caused by blocking at the light-shielding components 326-1 and 326-2 is 10% or less.

[0036] The following describes a method for adjusting the beam spacing in the device 30 to change the numerical aperture. Fig. Figure 4 is a diagram that schematically shows an exemplary method for changing a numerical aperture in the device for changing the numerical aperture according to the first embodiment. Fig. Figure 4 shows only the beam spacing change units 32-1 and 32-2 of the device 30 for changing the numerical aperture of Fig. 2. In addition, it shows Fig. 4. For convenience, side views of the beam spacing change units 32-1 and 32-2, seen from a Y-axis direction, and side views of the beam spacing change units 32-1 and 32-2, seen from an X-axis direction, are shown simultaneously. That is to say, Fig. Figure 4 simultaneously shows top views of the beam spacing change units 32-1 and 32-2 onto the ZX plane and top views of the beam spacing change units 32-1 and 32-2 onto the YZ plane.

[0037] In the beam spacing changer 31 of the device 30 for changing the numerical aperture of Fig. In Figure 4, the beam spacing change unit 32-1 is positioned closer to the laser oscillator 30 on one side, and the beam spacing change unit 32-2 is positioned closer to the transmission fiber 40 on one side. Beam spacing change unit 32-1 changes a beam spacing in the X-axis direction without changing a beam spacing in the Y-axis direction. Beam spacing change unit 32-2 changes a beam spacing in the Y-axis direction without changing a beam spacing in the X-axis direction. Note that the method is exemplified in Figure 4. Fig. 4 is shown, and the beam spacing change unit 32-1 and the beam spacing change unit 32-2 can change beam spacings in any directions different from each other.

[0038] In the example of Fig. 4. The transmission plates 322-1 and 323-1 of the beam spacing changer 32-1 are rotated by angles of θ1 and -θ1, respectively, with respect to the straight line A1. Furthermore, the transmission plates 322-2 and 323-2 of the beam spacing changer 32-2 are rotated by angles of θ2 and -θ2, respectively, with respect to a straight line A2. The straight line A2 is a straight line that passes through the rotation shafts 324-2 and 325-2 parallel to the X-axis. The angles θ1 and θ2 are adjusted to any desired angle such that the numerical entrance aperture NA_in of the transmission fiber 40 has a predetermined value.

[0039] Assume that laser oscillators 20A and 20B are arranged symmetrically with respect to the optical axis of transmission fiber 40, separated along the Y-axis. Laser oscillators 20A and 20B output laser beams LA and LB, respectively. The beam separation between laser beams LA and LB along the X-axis is denoted as ΔP1-1x, and the beam separation along the Y-axis is denoted as ΔP1-1y.

[0040] Fig. Figure 5 is a diagram that shows an example of changes in the state of the arrangement of laser beams in an XY plane. Fig. 4 shows. Fig. Figure 5 shows arrangement states in a plane perpendicular to the direction in which the laser beams LA and LB travel, at points R1, R2 and R3 in optical paths of the laser beams LA and LB. Fig. 4. Before entering the beam spacing change unit 32-1, the laser beams LA and LB are arranged with a separation in the Y-axis direction, as shown in arrangement state C1 at position R1. Furthermore, the laser beams LA and LB have a beam shape that is narrower in the X-axis direction than in the Y-axis direction, that is, an elliptical beam shape with a larger diameter in the Y-axis direction than in the X-axis direction. Then, in arrangement state C1, the laser beams LA and LB enter the beam spacing change unit 32-1.

[0041] Returning to Fig. In Figure 4, the two transmission plates 322-1 and 323-1 are arranged at a distance along the Y-axis in the beam spacing changer unit 32-1, and a rotating shaft 324-1 and a rotating shaft 325-1 are parallel to the Y-axis. The transmission plate 322-1 is arranged such that it transmits the laser beam LA from the laser oscillator 20A, and the transmission plate 323-1 is arranged such that it transmits the laser beam LB from the laser oscillator 20B. Furthermore, the two transmission plates 322-1 and 323-1 are rotatable about the Y-axis in the beam spacing changer unit 32-1. As described above, the transmission plate 322-1 and the transmission plate 323-1 are arranged such that the transmission plate 322-1 is inclined at an angle θ1 with respect to the straight line A1, and the transmission plate 323-1 is inclined at an angle -θ1 with respect to the straight line A1.It is possible to change the beam spacing in the X-axis direction by arranging the beam realignment unit 321-1 in this way.

[0042] The laser beams LA and LB enter the beam spacing changer 321-1. The laser beam LA enters the transmission plate 322-1, and the laser beam LB enters the transmission plate 323-1. The laser beams LA and LB are refracted upon entering the transmission plates 322-1 and 323-1, respectively. The laser beams LA and LB appear to travel in straight lines when viewed from a direction where no angle of incidence is specified, that is, when viewed in the YZ plane. Furthermore, the two transmission plates 322-1 and 323-1 are inclined in opposite directions by the same angle θ1 with respect to the straight line A1. As a result, the two laser beams LA and LB are refracted in directions away from each other in the ZX plane. The laser beams LA and LB are not refracted in the YZ plane.Although the laser beams LA and LB partially hit the light-shielding component 326-1, the laser beam LA passes at a rear side far from the light-shielding component 326-1 in the Y-axis direction in the ZX plane, and the laser beam LB passes at a front side far from the light-shielding component 326-1 in a direction opposite to the Y-axis direction in the ZX plane.

[0043] The laser beams LA and LB emitted by the beam spacing change unit 32-1 are arranged in a state that is in Fig. 5 is specified as arrangement state C2 at position R2. Dotted ellipses in arrangement state C2 indicate the positions of the laser beams LA and LB in arrangement state C1. As in Fig. As shown in Figure 5, the laser beam LA and the laser beam LB travel the same distance in opposite directions in the X-axis direction.

[0044] Returning to Fig. 4. The beam spacing between the laser beams LA and LB emitted by the beam spacing changer 32-1 in the X-axis direction is denoted by ΔP1-2x, and the beam spacing between them in the Y-axis direction is denoted by ΔP1-2y. In the example of Fig. 4. The beam spacing ΔP1-2x between the laser beams LA and LB emitted by the beam spacing change unit 32-1 in the X-axis direction is greater than the beam spacing ΔP1-1x between the laser beams LA and LB that have not yet entered the beam spacing change unit 32-1. The beam spacing ΔP1-2y between the laser beams LA and LB emitted by the beam realignment unit 321-1 in the Y-axis direction is equal to the beam spacing ΔP1-1y between the laser beams LA and LB that have not yet entered the beam realignment unit 321-1.

[0045] The beam spacing in the X-axis direction between the two laser beams LA and LB entering the beam spacing change unit 32-2 is denoted by ΔP2-1x, and the beam spacing between them in the Y-axis direction is denoted by ΔP2-1y. Note that 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.

[0046] Two laser beams, LA and LB, enter the beam spacing changer 32-2. Laser beam LA enters transmission plate 322-2, and laser beam LB enters transmission plate 323-2. The laser beams LA and LB are refracted upon entering transmission plate 322-2 and transmission plate 323-2, respectively. As in the beam spacing changer 32-1, the laser beams LA and LB appear to be refracted in the YZ plane, which is a direction in which the angles of incidence are specified. Furthermore, the laser beams LA and LB appear to travel in straight lines in the ZX plane, which is a direction in which no angle of incidence is specified. Additionally, the two transmission plates 322-2 and 323-2 are inclined in opposite directions by the same angle θ2 with respect to the straight line A2. As a result, the laser beams LA and LB are not refracted in the ZX plane.The two laser beams LA and LB are refracted in the YZ plane in a direction in which they approach each other. Although the laser beams LA and LB partially strike the light-shielding component 326-2, laser beam LA passes at a rear side far from the light-shielding component 326-2 in the X-axis direction in the YZ plane, and laser beam LB passes at a front side far from the light-shielding component 326-2 in a direction opposite to the X-axis direction in the YZ plane. Consequently, the two laser beams LA and LB are output by the beam spacing changer 32-2 such that the beam spacing in the X-axis direction between the two laser beams LA and LB is ΔP2-2x, and the beam spacing between them in the Y-axis direction is ΔP2-2y. In the example of... Fig. 4. The beam spacing ΔP2-2x is equal to the beam spacing ΔP2-1x in the X-axis direction between the two laser beams LA and LB that have not yet entered the beam spacing change unit 32-2. The beam spacing ΔP2-2y is smaller than the beam spacing ΔP2-1y between the two laser beams LA and LB that have not yet entered the beam spacing change unit 32-2.

[0047] The laser beams LA and LB emitted by the beam spacing change unit 32-2 are in a Fig. The laser beams are arranged in configuration C3 at position R3. Dotted ellipses in configuration C3 indicate the positions of laser beams LA and LB in configuration C2. As shown in Fig. As shown in Figure 5, the laser beams LA and LB travel the same distance in opposite directions in the Y-axis direction and lie on the X-axis.

[0048] As described above, the two elliptical laser beams LA and LB, which extend in the Y-axis direction and are spaced apart in the Y-axis direction as shown in arrangement state C1, pass through the two beam spacing change units 32-1 and 32-2 such that the laser beams LA and LB are spaced apart in the X-axis direction as shown in arrangement state C3. That is, the laser beams LA and LB can be rearranged by the beam spacing change units 32-1 and 32-2.

[0049] If the beam qualities of the laser beams LA and LB differ between the X-axis direction and the Y-axis direction, it is possible to rearrange the laser beams LA and LB as described above, thereby changing the beam diameter and divergence angle of the laser beam L to which the laser beams LA and LB were combined.

[0050] It is known that beam quality is represented by the product of beam diameter and divergence angle. The smaller the value obtained above, the better the quality of the laser beams LA and LB.

[0051] The beam diameter of a single laser beam can be obtained as a Gaussian beam diameter, as described above. A beam diameter determined from the energy distribution of the multiple laser beams LA and LB can be used as the beam diameter of the laser beam to which the LA and LB beams were combined. There are several definitions of beam diameter. Here, a beam diameter is understood to be a diameter that provides a predetermined percentage of the laser beam's energy. When a beam diameter is defined in this way, the beam diameter of the laser beam to which the LA and LB beams were combined varies depending on the arrangement of the multiple LA and LB laser beams. Consequently, the beam quality changes.

[0052] A case in which the multiple laser beams LA and LB are in the arrangement state C1 of Fig. The case in which the two laser beams LA and LB, arranged in the Y-axis direction, are combined is compared to a case in which the multiple laser beams LA and LB are combined in arrangement state C3, that is, a case in which the two laser beams LA and LB, arranged in the X-axis direction, are combined. The two elliptical laser beams LA and LB, which are narrower in the X-axis direction than in the Y-axis direction, are arranged with a certain distance in the Y-axis direction in arrangement state C1, and with a certain distance in the X-axis direction in arrangement state C3. The beam diameters of the laser beams LA and LB in the Y-axis direction are larger than their beam diameters in the X-axis direction. It can therefore be assumed that their beam quality in the Y-axis direction is worse than their beam quality in the X-axis direction.Furthermore, in a case where a region of the beam containing a predetermined percentage of the total energy is considered to provide the beam diameter, the beam diameter becomes smaller the closer the distance between the laser beams LA and LB is. Considering these findings, the beam quality in arrangement state C3, where the laser beams LA and LB are aligned in the X-axis direction, is considered better than in arrangement state C1, where the laser beams LA and LB are spaced apart in the Y-axis direction. For this reason, the two laser beams LA and LB are... Fig. 4 realigned by means of the two beam spacing change units 32-1 and 32-2 such that the arrangement state is changed from arrangement state C1 to arrangement state C3.

[0053] Note that the beam spacing change units 32-1 and 32-2 are capable of changing the beam spacings in various directions, and the inclination angles of the beam spacing change units 32-1 and 32-2 can also be set to any desired angle. As described above, because the shapes of the laser beams LA and LB in the XY plane are unequal (directional) with respect to the X-axis and the Y-axis, the degrees of displacement of the beam positions in the X-axis and Y-axis directions are set based on the shapes such that the numerical aperture of the laser beam L, to which the multiple laser beams LA and LB were combined, is essentially the same in the X-axis and Y-axis directions.The reason why the numerical aperture of the laser beam L should be essentially the same in the X-axis direction and the Y-axis direction is that the numerical exit aperture NA_out of the transmission fiber 40 depends on a larger numerical entry aperture NA_in.

[0054] The relationship between the inclination angles of the transmission plates 322-1, 322-2, 323-1 and 323-3 and the beam spacings is determined experimentally beforehand. In this way, the inclination angles of the transmission plates 322-1, 322-2, 323-1 and 323-3 can be obtained such that a laser beam produced by combining the two laser beams LA and LB emitted by the beam spacing changer 32-2 exhibits the desired beam quality.

[0055] Based on the above findings regarding beam quality, it is possible to obtain the best beam quality by overlapping the multiple laser beams LA and LB in such a way that the laser beams LA and LB are aligned. However, there is a case where a reflected laser beam, which is the laser beam L emitted by the processing head 50 and reflected by the workpiece 61, returns to the laser oscillator 20 with a distribution centered around the optical axis of the transmission fiber 40. Considering such a case, in the first embodiment, the light-shielding components 326-1 and 326-2 are arranged at positions corresponding to the optical axis of the transmission fiber 40 on the output sides of the beam spacing changer units 32-1 and 32-2, respectively, from which the laser beams LA and LB emerge.Because the light-shielding components 326-1 and 326-2 are arranged in this way, the multiple laser beams LA and LB cannot overlap in a compatible manner. That is, there is a limit to the reduction of the distance between the two laser beams LA and LB. In the presence of the light-shielding components 326-1 and 326-2, a beam separation is obtained that minimizes the beam quality of the two laser beams LA and LB. When the two laser beams LA and LB enter the input end of the transmission fiber 40 via the condensing optical system 33 with a beam separation that minimizes the beam quality, the acceptance angle of the transmission fiber 40 represents a minimum value. That is, the numerical input aperture NA_in of the transmission fiber 40 is minimized.

[0056] Note that, in order to minimize the beam quality of the two laser beams LA and LB, the multiple laser beams LA and LB must be arranged symmetrically with respect to the extension of the optical axis of the transmission fiber 40. This is because if the two laser beams LA and LB are not arranged symmetrically with respect to the extension of the optical axis of the transmission fiber 40, one of the two laser beams LA and LB will have a larger angle of incidence than the other. Because the numerical output aperture NA_out of the transmission fiber 40 depends on a larger numerical input aperture NA_in, it is necessary to decrease the numerical input aperture NA_in of the transmission fiber 40 in order to decrease the numerical output aperture NA_out of the transmission fiber 40.To reduce the numerical input aperture NA_in of the transmission fiber 40, it is necessary that the laser beam enters the transmission fiber 40 as far as possible from the extension of the optical axis of the transmission fiber 40. The numerical input aperture NA_in of the transmission fiber 40 is then minimized if the two laser beams LA and LB are arranged such that the output loss of the two laser beams LA and LB caused by the blockage at the light-shielding components 326-1 and 326-2 is 10% or less, and the two laser beams LA and LB have spatial distributions or spatial arrangements that are brought closest to each other and are symmetrical with respect to the extension of the optical axis of the transmission fiber 40.

[0057] As described above, not all of the laser beam L entering the transmission fiber 40 is transmitted by total internal reflection. The laser beam L transmitted by total internal reflection through the transmission fiber 40 is limited to the laser beam L that entered the transmission fiber 40 at an angle equal to or less than the maximum acceptance angle of the transmission fiber 40. The laser beam L that entered at an angle greater than the maximum acceptance angle of the transmission fiber 40 is not transmitted by the transmission fiber 40 and becomes radiated light, resulting in losses. At the maximum acceptance angle of the transmission fiber 40, the numerical input aperture NA_in of the transmission fiber 40 is maximized.

[0058] As described above, the rotation angles of the transmission plates 322-1, 322-2, 323-1, and 323-2 of the steel spacing change units 32-1 and 32-2 of the device 30 for changing the numerical aperture are set such that it is possible to change the numerical input aperture NA_in of the transmission fiber 40 between the minimum and maximum values. That is, given that the numerical input aperture should be between the minimum and maximum values, the rotation angles of the transmission plates 322-1, 322-2, 323-1, and 323-2 are set such that it is possible to change the beam quality, and in particular the beam diameter or the divergence angle of the laser beam L, to which the multiple laser beams LA and LB have been combined.

[0059] In this case, the operation of the beam spacing change units 32-1 and 32-2 can be limited such that the numerical input aperture NA_in does not exceed the maximum value of the numerical input aperture of the transmission fiber 40.

[0060] Furthermore, as in Fig. Figure 2 shows the numerical output aperture NA_out at the exit end of the transmission fiber 40 according to the numerical input aperture NA_in at the entry end of the transmission fiber 40. That is, the numerical output aperture NA_out of the transmission fiber 40 can be changed in the same way as the numerical input aperture NA_in. As described above, the device 30 for changing the numerical aperture in the first embodiment is able to change the numerical input aperture NA_in significantly between the minimum and maximum values ​​described above. Thus, the range of variation of the numerical output aperture NA_out can also be changed significantly according to the numerical input aperture NA_in.

[0061] Note that the above description of the device 30 for changing the numerical aperture with the two beam spacing change units 32-1 and 32-2 was given, but this is merely an example. In a case where the beam characteristics of the laser beams LA and LB emitted by the laser oscillators 20A and 20B differ between the X-axis and Y-axis directions, the device 30 for changing the numerical aperture only needs to have two or more beam spacing change units. However, if the beam characteristics of the laser beams LA and LB emitted by the laser oscillators 20A and 20B are not directional in the X-axis and Y-axis directions, the device 30 for changing the numerical aperture can have a single beam spacing change unit.Although the rotational waves 324-1 and 325-1 of the beam spacing changer 32-1 are perpendicular to the rotational waves 324-2 and 325-2 of the beam spacing changer 32-2, this is also only an example. The rotational waves 324-1 and 325-1 of the beam spacing changer 32-1 and the rotational waves 324-2 and 325-2 of the beam spacing changer 32-2 can extend in any direction, provided that the rotational waves 324-1 and 325-1 and the rotational waves 324-2 and 325-2 are perpendicular to the optical axis of the transmission fiber 40 and the direction of the rotational waves 324-1 and 325-1 is different from the direction of the rotational waves 324-2 and 325-2.

[0062] Furthermore, the rotational positions of the beam realignment units 321-1 and 321-2, that is, the inclinations of the transmission plates 322-1, 322-2, 323-1 and 323-2, can be controlled in any desired manner. Alternatively, preset angles can be stored such that the transmission plates 322-1, 322-2, 323-1 and 323-2 are rotated by the preset angles according to commands from the control unit 70.

[0063] The device 30 for changing the numerical aperture of the first embodiment includes the multiple beam spacing change units 32-1 and 32-2. The beam spacing change units 32-1 and 32-2 rearrange the multiple laser beams LA and LB and change the numerical input aperture NA_in of the transmission fiber 40 when the multiple realigned laser beams LA and LB are condensed to enter the transmission fiber 40. The multiple beam spacing change units 32-1 and 32-2 include the light-shielding components 326-1 and 326-2, respectively. The light-shielding components 326-1 and 326-2 are provided on sides that are closer to the transmission fiber 40 with respect to the beam spacing change units 32-1 and 32-2, respectively, and are provided in regions that include the extension of the optical axis of the transmission fiber 40.As a result, a reflected laser beam, which is a laser beam reflected from the workpiece 61 and returns to the laser oscillator 20 with a distribution centered on the optical axis of the transmission fiber 40, can be blocked without being transmitted to the laser oscillator 20. This means that it is possible to control both the numerical output aperture NA_out of the transmission fiber 40 and to prevent the laser oscillator 20 from failing due to the reflected laser beam. Furthermore, even if the volume of the laser beam reflected from the workpiece 61 is large, it is possible to ensure that the laser oscillator 20 operates without failure.

[0064] Furthermore, the beam spacing adjustment unit 32-1 includes the two transmission plates 322-1 and 323-1 and the rotation mechanisms. The transmission plates 322-1 and 323-1 are rotatable about the rotation shafts 324-1 and 325-1, respectively. The rotation mechanisms operate and rotate the transmission plates 322-1 and 323-1 about the rotation shafts 324-1 and 325-1, respectively, in such a way that the desired inclinations are achieved. The beam spacing adjustment unit 32-2 also includes the two transmission plates 322-2 and 323-2 and the rotation mechanisms. The transmission plates 322-2 and 323-2 are rotatable about the rotation shafts 324-2 and 325-2, respectively. The rotation mechanisms operate and rotate the transmission plates 322-2 and 323-2 around the rotation shafts 324-2 and 325-2 respectively, in such a way that the desired inclinations are achieved.Furthermore, the laser beam machine 1 includes the control unit 70, which controls the inclinations of the transmission plates 322-1, 322-2, 323-1, and 323-2 via the rotation mechanisms. The control unit 70 is able to adjust the beam spacing between the laser beams LA and LB to predetermined angles by setting the inclinations of the two transmission plates 322-1 and 323-1 of the beam spacing changer 32-1 and the inclinations of the two transmission plates 322-2 and 323-2 of the beam spacing changer 32-2. This means that it is possible to control the numerical input aperture NA_in of the transmission fiber 40 between its minimum and maximum values. Furthermore, because the variable range of the numerical input aperture NA_in can be increased, the variable range of the numerical output aperture NA_out can also be increased.

[0065] Furthermore, the multiple laser beams LA and LB are arranged such that they are symmetrical with respect to the extension of the optical axis of the transmission fiber 40. That is, the laser oscillators 20A and 20B are arranged such that they are symmetrical with respect to the extension of the optical axis of the transmission fiber 40. In addition, the transmission plates 322-1 and 323-1 are arranged such that they are symmetrical with respect to the extension of the optical axis of the transmission fiber 40. Thus, the beam quality of the laser beam L containing the multiple laser beams LA and LB can be made symmetrical. Moreover, even if the multiple laser beams LA and LB exhibit insufficient beam quality, they can be realigned to improve it.

[0066] In one example, the control unit 70 described above is implemented by a processing circuit that acts as a circuit causing a processor to execute software. The processing circuit that causes the software to be executed is, for example, one in Fig. 6 control circuits shown. Fig. Figure 6 is a diagram showing an exemplary hardware configuration of the control unit of the laser beam machine according to the first embodiment. A control circuit 100 includes an input unit 101, a processor 102, a memory 103, and an output unit 104.

[0067] The input unit 101 is an interface circuit that receives data from outside the control circuit 100 and provides the data 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 a case where the processing circuit is in Fig. In the control circuit 100 shown in Figure 6, the laser oscillator 20, the numerical aperture changing device 30, the processing head 50, and the processing table 60 are implemented by the processor 102, which reads and executes programs for controlling the laser oscillator 20, the numerical aperture changing device 30, the processing head 50, and the processing table 60. The programs are stored in memory 103. The processor can output data such as a calculation result to memory 103 to store the data in memory 103 z, or it can store the data such as a calculation result via the volatile memory of memory 103 in an auxiliary storage device.

[0068] The processor 102 is a CPU (central processing unit, also called processor device, arithmetic device, microprocessor, microcomputer, processor or DSP (digital signal processor)). Examples of memory 103 include non-volatile or volatile semiconductor memories such as RAM (random access memory), ROM (read-only memory), flash memory, EPROM (erasable programmable read-only memory) and EEPROM (registered trademark) (electrically erasable programmable read-only memory), magnetic disk, flexible disk, optical disk, compact disk, mini-disc and DVD (digital versatile disc).

[0069] Fig.Figure 6 shows an example of hardware for use in a case where the control unit 70 is implemented as the processor 102 and the memory 103 as a general-purpose processor and general-purpose memory, respectively. The control unit 70 can be implemented as a purpose-oriented hardware circuit. A processing circuit, such as the purpose-oriented hardware circuit, is a single circuit, a parallel-programmed processor, an ASIC (application-specific integrated circuit), an FPGA (field-programmable array), or a combination thereof. The constituent elements described above can be implemented by a combination of the control circuit 100 and the purpose-oriented hardware circuit.

[0070] The configurations shown in the above embodiments are examples, and it is possible to combine the configurations with other known technology, and it is also possible to partially omit or modify the configurations without deviating from the scope of the present disclosure. Reference symbol list 1 laser beam machine 10 laser devices 20, 20A, 20B Laser oscillator 30 Device for changing the numerical aperture 31 Beam spacing modifiers 32-1, 32-2 Beam Spacing Change Unit 33 condensing optical system 40 transmission fibers 41 core 42 Envelope 50 processing heads 51 transmitting optical system 60 machining table 61 workpiece 70 Control unit 100 control circuit 101 Input unit 102 processor 103 storage 104 output units 321-1, 321-2 Beam Realignment Unit 322-1, 322-2, 323-1, 323-2 transmission plate 324-1, 324-2, 325-1, 325-2 rotary shaft 326-1, 326-2 Light-shielding component A1, A2 straight line L, LA, LB Laser beam

Claims

[1] Device (30) for changing the numerical aperture for realigning spatial distributions or spatial positions of several laser beams (LA, LB) incident from a laser oscillator (20) and propagating in the direction of an axis (Z), and for condensing the several realigned laser beams for entry of the beams into a transmission fiber (40), wherein the device for changing the numerical aperture is characterized by: a light-shielding component (326-1, 326-2) provided in an extension of the optical axis of the transmission fiber (40), wherein the light-shielding component (326-1, 326-2) blocks a reflected laser beam, the reflected laser beam being a laser beam traveling from the transmission fiber (40) to the laser oscillator (20); and Several beam spacing change units (32-1, 32-2) for changing beam spacings between the several incident laser beams (LA, LB) in two different directions (X, Y), wherein one of the several beam spacing change units (32-1) is configured to change a beam spacing in a first direction (X) perpendicular to the axis (Z), and another of the several beam spacing change units (32-2) is configured to change a beam spacing in a second direction (Y) different from the first direction (X), wherein for each of the multiple beam spacing change units (32-1, 32-2) a light shielding component (326-1, 326-2) is provided, and each of the light shielding components (326-1, 326-2) is arranged on one side closer to the transmission fiber (40) with respect to the corresponding beam spacing change unit (32-1, 32-2). [2] Device (30) for changing the numerical aperture according to claim 1, wherein each of the light-shielding components (326-1, 326-2) is of such a size that the output loss of the multiple laser beams is 10% or less when the spatial distributions or spatial positions of the multiple incident laser beams in the device (30) for changing the numerical aperture are brought closest to each other. [3] Device (30) for changing the numerical aperture according to claim 1, wherein the light-shielding components (326-1, 326-2) are arranged such that the output loss of the multiple laser beams is 10% or less when the spatial distributions or spatial positions of the multiple incident laser beams in the device (30) for changing the numerical aperture are brought closest to each other. [4] Device (30) for changing the numerical aperture according to claim 1, wherein the light-shielding components (326-1, 326-2) are formed from a material that absorbs or reflects the reflected laser beam. [5] Device (30) for changing the numerical aperture according to claim 4, wherein each of the light-shielding components (326-1, 326-2) has a cooling mechanism. [6] Device (30) for changing the numerical aperture according to claim 1, further comprising: a control unit (70) for controlling the operation of the multiple beam spacing change units (32-1, 32-2), wherein Each of the multiple beam spacing change units (32-1, 32-2) includes: a beam realignment unit (321-1; 321-2) with several transmission plates (322-1, 323-1; 322-2, 323-2) arranged at predetermined intervals, wherein the several transmission plates transmit the laser beams (LA, LB); and a rotation mechanism for rotating each of the transmission plates around a rotating shaft, and The control device controls the rotation mechanism in such a way that the multiple laser beams enter the multiple transmission plates at predetermined angles. [7] Device (30) for changing the numerical aperture according to claim 6, wherein the multiple laser beams (LA, LB) are incident symmetrically into the device (30) for changing the numerical aperture with respect to the extension of the optical axis of the transmission fiber (40), and the multiple transmission plates (322-1, 323-1; 322-2, 323-2) are arranged symmetrically with respect to the extension of the optical axis of the transmission fiber (40). [8] Laser device (10), comprising: the device (30) for changing the numerical aperture according to any one of claims 1 to 7; and the laser oscillator (20) to cause the multiple laser beams (LA, LB) to enter the device (30) for changing the numerical aperture. [9] Laser beam machine (1), comprising: the laser device (10) according to claim 8; a transmission fiber (40) for transmitting the multiple laser beams (LA, LB) from the laser device (10); and a processing head (50) for irradiating a workpiece with the multiple laser beams (LA, LB) from the transmission fiber (40).

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