Laser processing head and laser processing device including the same, and method for adjusting condensed positions of first laser beam and second laser beam

Abstract

To provide a laser processing head having an optical scanner for scanning a processed surface of workpiece with a laser beam which can condense laser beams having different wavelengths at the same condensed position with a simple configuration.SOLUTION: A laser processing head 50 includes a housing 51 to which an optical fiber 40 is connected, a collimation lens 52 arranged in the inside of the housing 51, a focus lens 53 of which a chromatic aberration is corrected, an optical component moving mechanism 57 for moving the collimation lens 52 in a Z direction, and first and second galvano mirrors 55B and 56B. The optical fiber 40 has a first core 41 to which a first laser beam LB1 having a wavelength λ1 is guided, and a second core 43 to which a second laser beam LB2 having a wavelength λ2 (λ1>λ2) is guided. The first and second galvano mirrors 55B and 56B two-dimensionally scans a processed surface 90A of workpiece 90 with the first and second laser beams LB1 and LB2.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present disclosure relates to a laser processing head, a laser processing apparatus including the same, and a method for adjusting the focusing positions of a first laser beam and a second laser beam. [Background technology]

[0002] In recent years, in laser processing such as welding and cutting of copper materials, a so-called hybrid laser processing method has been put into practical use, which combines visible laser light, which has a high light absorption rate in copper, such as blue laser light or green laser light, with infrared laser light.

[0003] Conventionally, a laser processing device for performing hybrid laser processing has been proposed in which laser light of different wavelengths is guided to a laser processing head using different fibers, and then combined inside the laser processing head and irradiated onto a workpiece (see, for example, Patent Document 1).

[0004] Separately from this, a configuration has also been proposed in which laser beams of different wavelengths are guided to a laser processing head using a multicore fiber (see, for example, Patent Documents 2 and 3). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2022-088352 A [Patent Document 2] Patent Publication No. 2021-086840 [Patent Document 3] International Publication No. 2021 / 145358 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the conventional laser processing devices disclosed in Patent Documents 1 to 3 have the following problems. First, when two laser beams with different wavelengths are irradiated from a laser processing head toward a workpiece to be processed, a deviation occurs in the focusing position of each laser beam due to the influence of chromatic aberration of a lens arranged inside the laser processing head. In practice, in order to correct such a deviation, it is necessary to provide a mechanism for adjusting the focusing position of one of the laser beams inside or outside the laser processing head.

[0007] However, providing such an adjustment mechanism may increase the size of the laser processing head, complicate the laser processing head or the laser processing device, and increase costs due to the provision of the focusing position adjustment mechanism.

[0008] Next, in the conventional configurations disclosed in Patent Documents 1 and 2, it is necessary to provide an optical fiber separately for guiding laser beams of different wavelengths to the laser processing head. For example, in the configuration disclosed in Patent Document 1, a total of two optical fibers are required to guide two laser beams of different wavelengths to the laser processing head.

[0009] However, because these optical fibers guide high-power laser light, they deteriorate over time and must be replaced periodically. In other words, the initial cost and running cost required for maintenance increase according to the number of optical fibers that guide the laser light. In addition, when connecting multiple optical fibers to a laser processing head, a connection mechanism must be provided for each optical fiber, which may increase the size of the laser processing head.

[0010] In laser processing, an optical scanner is provided on a laser processing head, and the laser beam is irradiated onto the workpiece while the optical scanner is operated to two-dimensionally scan the laser beam on the processing surface of the workpiece. In this case, a difference occurs in the optical path length of the laser beam between the end and center of the scanning trajectory, so that the focusing position at the end shifts along the irradiation direction of the laser beam relative to the focusing position at the center.

[0011] Conventionally, an fθ lens is used to adjust the focal position on the processing surface so that it coincides with the end and center of the scanning trajectory. However, when irradiating a workpiece with two laser beams of different wavelengths, the difference in chromatic aberration cannot be corrected simultaneously, and deviation in the focal position occurs due to chromatic aberration.

[0012] The present disclosure has been made in consideration of these points, and its purpose is to provide a laser processing head equipped with an optical scanner for scanning laser light on the processing surface of a workpiece, capable of focusing laser light of different wavelengths at the same focusing position, a laser processing head equipped with the same, a laser processing apparatus equipped with the same, and a method for adjusting the focusing positions of a first laser light and a second laser light. [Means for solving the problem]

[0013] In order to achieve the above object, a laser processing head according to the present disclosure is a laser processing head including a housing and a plurality of optical components arranged inside the housing, the housing has a fiber connection port and a light exit port, an optical fiber is connected to the fiber connection port, the optical fiber has at least a first core provided at an axial center and a second core provided radially outward of the first core and coaxially with the first core, a first laser light having a first wavelength is guided to the first core, a second laser light having a second wavelength shorter than the first wavelength is guided to the second core, at least one of the first laser light and the second laser light is emitted from the light exit port toward a workpiece, the plurality of optical components include at least a first lens, a second lens, a first mirror, and a second mirror, the first mirror and the second mirror are arranged in front of the first lens and the second lens, The laser beam scanning device is arranged at a position close to the light exit port, and the first mirror is configured to scan the incident first laser light or the second laser light, or both, in a Y direction that is a direction in a plane intersecting a Z direction that is a traveling direction of the first laser light and the second laser light, and the second mirror is configured to scan the incident first laser light or the second laser light, or both, in an X direction that intersects the Y direction in the plane, the first laser light passes through a central portion of each of the first lens and the second lens, and the second laser light passes through an outer periphery of each of the first lens and the second lens, and chromatic aberration of the second lens is corrected so that the first laser light and the second laser light are focused at the same position on the machining surface of the workpiece or in the vicinity of the machining surface, and further includes an optical component moving mechanism that moves the first lens along the Z direction.

[0014] The laser processing apparatus according to the present disclosure is characterized by comprising at least the laser processing head, a first laser oscillator that generates the first laser light, a second laser oscillator that generates the second laser light, an optical coupler that receives at least one of the first laser light and the second laser light and causes the first laser light to be incident on the first core and the second laser light to be incident on the second core, and an optical fiber that is connected to the optical coupler and the laser processing head and guides at least one of the first laser light and the second laser light from the optical coupler to the laser processing head. Effect of the Invention

[0015] According to the present disclosure, in a laser processing head equipped with an optical scanner for scanning a laser beam on a processing surface of a workpiece, it is possible to focus laser beams of different wavelengths at the same focusing position with a simple configuration, and it is also possible to prevent the laser processing head from becoming large. [Brief description of the drawings]

[0016] [Figure 1] 1 is a schematic configuration diagram of a laser processing device according to a first embodiment. [Diagram 2] FIG. 2 is a schematic diagram of an optical fiber as viewed from an input end. [Diagram 3] FIG. 2 is a schematic cross-sectional view of a main part of an optical coupler. [Figure 4] FIG. 2 is a diagram showing the appearance of a laser processing head. [Diagram 5] FIG. 2 is a schematic diagram of the inside of the laser processing head. [Figure 6] FIG. 2 is an enlarged view of a collimation lens and a focus lens. [Figure 7A] FIG. 4 is a side view of the optical component moving mechanism. [Figure 7B] FIG. 2 is an exploded perspective view of an optical component moving mechanism. [Figure 7C] FIG. 7C is a cross-sectional view taken along line VIIC-VIIC in FIG. 7A. [Figure 8] 2 is a schematic diagram showing the arrangement of optical components inside the laser processing head. FIG. [Figure 9] FIG. 1 is a diagram showing the wavelength dependence of optical absorptance in various metals. [Figure 10] 4 is a schematic diagram showing the power density distribution of a first laser beam and a second laser beam in the vicinity of an output end of an optical fiber. FIG. [Figure 11] 13 is a schematic diagram showing the arrangement of optical components inside a laser processing head according to a modified example. FIG. [Figure 12] 13 is a schematic diagram showing another arrangement relationship of optical components inside the laser processing head according to the modified example. FIG. [Figure 13] 13 is a schematic diagram showing yet another arrangement relationship of optical components inside the laser processing head according to the modified example. FIG. [Figure 14] 10A to 10C are schematic diagrams showing a method for adjusting the focusing positions of the first laser beam and the second laser beam in the second embodiment. [Figure 15] FIG. 2 is a perspective view of a collimation lens held in a lens barrel part. [Figure 16A] 13A and 13B are diagrams showing temperature distributions of the lens barrel parts and the collimation lens after the heater is operated. [Figure 16B] FIG. 13 is a diagram showing the temperature distribution of the collimation lens after the heater is operated. [Figure 17] 5A to 5C are schematic diagrams showing an example of a temperature distribution of an optical component before temperature adjustment and a difference in the focusing position of a first laser beam and a second laser beam. [Figure 18] 5A to 5C are schematic diagrams showing an example of the temperature distribution of an optical component after temperature adjustment and the focusing positions of a first laser beam and a second laser beam. [Figure 19] 13A and 13B are schematic diagrams showing another example of the temperature distribution of the optical component before temperature adjustment and the difference in the focusing positions of the first laser light and the second laser light. [Figure 20] 11A and 11B are schematic diagrams showing another example of the temperature distribution of the optical components after temperature adjustment and the focusing positions of the first laser light and the second laser light. [Figure 21] 10 is a flowchart showing a procedure for adjusting the focusing positions of the first laser light and the second laser light. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. Note that the following description of the preferred embodiments is merely illustrative in nature and is not intended to limit the present disclosure, its application, or its uses.

[0018] (Embodiment 1) [1: Configuration of laser processing equipment] Fig. 1 is a schematic diagram of a laser processing device according to the first embodiment. Fig. 2 is a schematic diagram of an optical fiber viewed from an incident end. The laser processing device 200 includes a first laser oscillator 10, a second laser oscillator 20, an optical coupler 30, an optical fiber 40, a laser processing head 50, a manipulator 70, a control unit 80, and a stage 100. For ease of explanation, the shape of the laser processing head 50 is simplified in Fig. 1.

[0019] In the following description, the traveling direction of the laser light irradiated from the laser processing head 50 to the workpiece 90 may be referred to as the Z direction. In addition, in Fig. 1, the direction from the optical coupler 30 toward the laser processing head 50 may be referred to as the X direction, and the direction perpendicular to the X direction and the Z direction may be referred to as the Y direction. In addition, in the Z direction, the side where the fiber connection port 51A (see Fig. 4) of the laser processing head 50 is provided may be referred to as the upper or upper side, and the side where the light exit port 51B (see Figs. 4 and 5) is provided may be referred to as the lower or lower side.

[0020] In this specification, "same," "orthogonal," or "parallel" means the same, or orthogonal, or parallel, including the manufacturing tolerance of each part in the laser processing apparatus 200 and the allowable tolerance of the positional relationship of each part, and does not mean that the two objects being compared are the same, or orthogonal, or parallel in the strict sense.

[0021] Furthermore, when laser processing the workpiece 90, the first laser beam LB1 and the second laser beam LB2 are irradiated along a processing line (not shown) on the processing surface 90A of the workpiece 90.

[0022] The first laser oscillator 10 emits a first laser light LB1. In this embodiment, the wavelength λ1 of the first laser light LB1 is 975 nm. The wavelength λ1 of the first laser light LB1 is not particularly limited to this. The first laser light LB1 may be a laser light in the near-infrared or infrared wavelength region. The wavelength λ1 may be appropriately selected within the range of 800 nm or more and 1200 nm or less.

[0023] The second laser oscillator 20 emits the second laser light LB2. In this embodiment, the wavelength λ2 of the second laser light LB2 is 450 nm. The wavelength λ2 of the second laser light LB2 is not particularly limited to this. The second laser light LB2 may be a laser light in the near ultraviolet or visible light wavelength region. The wavelength λ2 may be appropriately selected within the range of 380 nm or more and 660 nm or less.

[0024] The first laser oscillator 10 and the second laser oscillator 20 each have a laser light source and a power source (not shown). Based on a control signal from the control unit 80, the respective power sources are driven to operate the laser light sources and generate the first laser light LB1 and the second laser light LB2, respectively. The laser light source may be composed of one or more semiconductor laser elements, or may be a solid-state laser or a fiber laser. Note that the semiconductor laser element is preferably a laser diode bar having a plurality of emitters that each emits laser light.

[0025] The optical coupler 30 is connected to the optical fiber 40, receives the first laser light LB1 emitted from the first laser oscillator 10, and makes the first laser light LB1 incident on a first core 41 (see FIGS. 2 and 3) of the optical fiber 40. The optical coupler 30 also receives the second laser light LB2 emitted from the second laser oscillator 20, and makes the second laser light LB2 incident on a second core 43 (see FIGS. 2 and 3) of the optical fiber 40. The configuration of the optical coupler 30 will be described in detail later.

[0026] As shown in FIG. 2, the optical fiber 40 has at least a first core 41 and a second core 43, each of which is an optical waveguide, and a first clad 42 and a second clad 44, and the outer surface of the second clad 44 is covered with a light-shielding coating (not shown).

[0027] When viewed from the incident end 40A of the optical fiber 40 (see FIG. 3), the first core 41 is circular and disposed at the axis of the optical fiber 40. The first clad 42 is in contact with the outer peripheral surface of the first core 41 and disposed coaxially with the first core 41, and is ring-shaped when viewed from the incident end 40A. The second core 43 is in contact with the outer peripheral surface of the first clad 42 and disposed coaxially with the first core 41, and is ring-shaped when viewed from the incident end 40A. The second clad 44 is in contact with the outer peripheral surface of the second core 43 and disposed coaxially with the first core 41, and is ring-shaped when viewed from the incident end 40A.

[0028] The first core 41, the second core 43, the first cladding 42, and the second cladding 44 are all made of quartz. However, the refractive index of the first cladding 42 is set to be lower than the refractive indexes of the first core 41 and the second core 43. In addition, the refractive index of the second cladding 44 is set to be lower than the refractive index of the second core 43.

[0029] In addition, the optical characteristics of the first core 41 are preferably adjusted so that the transmission loss of the first laser light LB1 is minimized or extremely small, and the optical characteristics of the second core 43 are preferably adjusted so that the transmission loss of the second laser light LB2 is minimized or extremely small. From another perspective, the optical characteristics of the first core 41 are preferably adjusted so that the transmission loss of the second laser light LB2 is smaller than the transmission loss of the first laser light LB1. The optical characteristics of the second core 43 are preferably adjusted so that the transmission loss of the first laser light LB1 is smaller than the transmission loss of the second laser light LB2. The adjustment of these optical characteristics is performed, for example, by appropriately setting the amount of impurity introduced into the first core 41, the second core 43, the first cladding 42, and the second cladding 44. In addition, the adjustment is performed by appropriately setting the refractive index difference between the first core 41 and the first cladding 42 and the refractive index difference between the second core 43 and the first cladding 42 and the second cladding 44.

[0030] The laser processing head 50 receives the first laser light LB1 and the second laser light LB2 guided by the optical fiber 40, and further irradiates the first laser light LB1 and the second laser light LB2 toward the workpiece 90. The structure of the laser processing head 50 will be described in detail later.

[0031] The manipulator 70 has an arm 71. The laser processing head 50 is attached to the tip of the arm 71. The arm 71 is divided into a plurality of sections, and a joint shaft 72 is provided at each connecting portion of each section.

[0032] Based on a control signal from the control unit 80, the manipulator 70 moves the laser processing head 50 along the processing line described above, and changes the position of the laser processing head 50 with respect to the workpiece 90. In accordance with this operation, the irradiation positions of the first laser beam LB1 and the second laser beam LB2 on the processing surface 90A of the workpiece 90 move along the processing line, and laser processing is performed.

[0033] As described above, the control unit 80 controls the operation of each of the first laser oscillator 10 and the second laser oscillator 20. Specifically, the control unit 80 controls the timing and emission time of the start and stop of emission of the first laser light LB1, as well as the power of the first laser light LB1. The control unit 80 also controls the timing and emission time of the start and stop of emission of the second laser light LB2, as well as the power of the second laser light LB2.

[0034] In addition, the control unit 80 is connected to the manipulator 70, the optical coupler 30, and the laser processing head 50, and controls the operation of the manipulator 70 and the operation of the actuator 33 (see Figure 3) and the first to third galvanometer motors 55A, 56A, 57A (see Figures 4 and 5), which will be described later.

[0035] The above-mentioned functions of the control unit 80 are realized by executing a predetermined machining program on the hardware of the control unit 80. The hardware is composed of one or more central processing units (CPUs) and memories. The memories are, for example, semiconductor memories such as random access memories (RAMs) and solid state drives (SSDs). The memories may also be read only memories (ROMs) or RAMs built into the CPUs.

[0036] 1 shows an example in which the control unit 80 controls the operations of the first laser oscillator 10, the second laser oscillator 20, the manipulator 70, the optical coupler 30, and the laser processing head 50. However, a control unit 80 may be provided separately for each device. In that case, a host control unit may be provided that operates the multiple control units 80 in cooperation with each other based on a predetermined processing program.

[0037] The position of the workpiece 90 relative to the laser processing device 200 is determined by placing the workpiece 90 on the stage 100. After the positioning of the workpiece 90 is completed, the workpiece 90 is laser processed in accordance with a predetermined processing program. In this case, whether the laser processing is performed using only the first laser light LB1, only the second laser light LB2, or both the first laser light LB1 and the second laser light LB2 is appropriately changed depending on the material of the workpiece 90 and the processing mode.

[0038] In this embodiment, the stage 100 is fixed and stationary at one location, but the stage 100 may be configured to be movable along an XY plane including the X and Y directions by providing a stage movement mechanism (not shown) on the stage 100. In this case, the position of the manipulator 70, in other words, the position of the laser processing head 50, may be fixed.

[0039] [2: Configuration of optical coupler] 3 is a schematic cross-sectional view of the main part of the optical coupler 30. The optical coupler 30 has a housing 31 and a plurality of components arranged in a predetermined positional relationship inside the housing 31. The plurality of components include a reflecting mirror 32, an actuator 33, a dichroic mirror 34, and a first focus lens 35.

[0040] The housing 31 has a first light inlet 31A (see FIG. 1), a second light inlet 31B (see FIG. 1), and a light outlet 31C. As shown in FIG. 1, a first laser light LB1 is incident from the first laser oscillator 10 into the inside of the housing 31 through the first light inlet 31A. Also, a second laser light LB2 is incident from the second laser oscillator 20 into the inside of the housing 31 through the second light inlet 31B.

[0041] An optical fiber 40 is connected to the light exit port 31C. A quartz block 36 for adjusting the refractive index is welded to an incident end 40A of the optical fiber 40, and the first laser light LB1 and the second laser light LB2 are transmitted through the quartz block 36 and are incident on the incident end 40A of the optical fiber 40.

[0042] Although not shown, the first light inlet 31A is sealed with a member such as quartz glass that is transparent to the first laser light LB1. Similarly, the second light inlet 31B is sealed with a member such as quartz glass that is transparent to the second laser light LB2. The arrangement of the first light inlet 31A and the second light inlet 31B may be different from the example shown in Fig. 1. In that case, a component that changes the optical path of the first laser light LB1 and the second laser light LB2 is provided inside the housing 31.

[0043] The reflecting mirror 32 reflects the second laser light LB2 incident inside the housing 31 toward the incident end 40A of the optical fiber 40. The actuator 33 is attached to the reflecting mirror 32, and adjusts the angle of the reflecting mirror 32 with respect to the optical axis of the second laser light LB2 based on a control signal from the control unit 80. When the second laser light LB2 reflected by the reflecting mirror 32 is not incident on the second core 43 at the incident end 40A, the actuator 33 is operated to adjust the angle of the reflecting mirror 32 so that the second laser light LB2 is incident on the second core 43. The actuator 33 is, for example, a piezo motor, but is not particularly limited thereto.

[0044] The dichroic mirror 34 is an optical component configured to transmit light in the visible wavelength range including the wavelength λ2 of the second laser light LB2, while reflecting light in the near-infrared and infrared wavelength range including the wavelength λ1 of the first laser light LB1. Specifically, dielectric films having different refractive indices are formed on the surface of the dichroic mirror 34, and the type, film thickness, and number of layers are adjusted to obtain the above-mentioned optical characteristics.

[0045] The dichroic mirror 34 is disposed on the optical path of the second laser light LB2 reflected by the reflecting mirror 32 and on the optical path of the first laser light LB1 incident on the inside of the housing 31. The second laser light LB2 transmitted through the dichroic mirror 34 and the first laser light LB1 reflected by the dichroic mirror 34 travel toward the first focus lens 35 with their optical axes approaching each other.

[0046] The first focus lens 35 focuses the incident first laser light LB1 and second laser light LB2, respectively, and makes them incident on the incident end 40A of the optical fiber 40. As described above, at the incident end 40A, the first laser light LB1 is focused by the first focus lens 35 so as to be incident on the first core 41, and the second laser light LB2 is focused on the second core 43.

[0047] The first laser light LB1 is guided by the first core 41 and the second laser light LB2 is guided by the second core 43, respectively, and enters the laser processing head 50.

[0048] The optical fiber 40 is attached to the housing 31 so as to be movable in each of the X direction, Y direction, and Z direction to such an extent that the optical fiber 40 does not fall out of the light exit port 31C. When the first laser light LB1 is not incident on the first core 41 at the incident end 40A, the position of the optical fiber 40 is adjusted so that the first laser light LB1 is incident on the first core 41.

[0049] [3: Laser processing head configuration] <3-1: Overview of the laser processing head> Fig. 4 is a diagram showing the external appearance of the laser processing head, Fig. 5 is a schematic diagram showing the inside of the laser processing head, and Fig. 6 is an enlarged view of the collimation lens and the focus lens.

[0050] For ease of explanation, the cross-sectional structure of the optical fiber 40 is omitted in Fig. 4. Components other than those shown in Fig. 4 may be disposed inside the housing 51 or attached to the outside of the housing 51.

[0051] 4 and 5, the laser processing head 50 has a housing 51 and a plurality of optical components disposed therein. The laser processing head 50 also has first to third galvanometer motors 55A, 56A, and 57A attached to the housing 51.

[0052] The housing 51 has a fiber connection port 51A to which the emission end 40B of the optical fiber 40 is attached, and a light emission port 51B from which the first laser light LB1 and the second laser light LB2 are emitted. In addition, a first base 57B and a second base 57D, which are parts of the housing 51, are components of an optical component moving mechanism 57 (see FIGS. 7A to 7C).

[0053] Inside the housing 51, a collimation lens 52, a second focus lens 53, a reflecting mirror 54, a first galvanometer mirror 55B, and a second galvanometer mirror 56B are arranged in a predetermined positional relationship with each other in that order from the closest to the fiber connection port 51A. In the following description, the second focus lens 53 may be simply referred to as the focus lens 53.

[0054] In addition, optical components other than these may be arranged inside the housing 51. For example, a protective glass may be provided near the light exit port 51B. By providing the protective glass, it is possible to prevent spatters and fumes generated on the workpiece 90 irradiated with the first laser light LB1 and the second laser light LB2 from entering the inside of the housing 51. In this way, it is possible to prevent spatters and fumes from adhering to the optical components arranged inside the housing 51, deteriorating the optical properties of the optical components, and ultimately reducing the power and beam quality of each of the first laser light LB1 and the second laser light LB2 irradiated to the workpiece 90.

[0055] The collimation lens 52 receives and collimates the first laser beam LB1 and the second laser beam LB2 that are incident inside the housing 51. As will be described later, the collimation lens 52 is held by an optical component moving mechanism 57 and configured to be movable along the Z direction. The configuration and operation of the optical component moving mechanism 57 will be described later.

[0056] The focus lens 53 receives the first laser light LB1 and the second laser light LB2 collimated by the collimation lens 52, and focuses the light so as to form a focal point on the processing surface 90A of the workpiece 90 or in the vicinity of the processing surface 90A. In other words, the focusing positions of the first laser light LB1 and the second laser light LB2 transmitted through the focus lens 53 are the processing surface 90A or in the vicinity of the processing surface 90A. In this embodiment, the first galvanometer mirror 55B and the second galvanometer mirror 56B are tilted so that the focusing positions of the first laser light LB1 and the second laser light LB2 are the same within a range where the processing surface 90A is scanned with the first laser light LB1 and the second laser light LB2.

[0057] Here, the shapes of the collimation lens 52 and the focus lens 53 through which the first laser beam LB1 and the second laser beam LB2 pass, respectively, will be further described.

[0058] 6, the collimation lens 52 is a lens having a convex emission surface (hereinafter referred to as a light emission surface) for the first laser light LB1 and the second laser light LB2, and the focus lens 53 is a lens having a convex incidence surface (hereinafter referred to as a light incidence surface) for the first laser light LB1 and the second laser light LB2.

[0059] However, in the focus lens 53, the radius of curvature of the light incident surface is not uniform, and the focus lens 53 is a so-called aspheric lens.

[0060] Specifically, when the radius of curvature of the light incident surface at the center portion 53A of the focus lens 53 is R2A and the radius of curvature of the light incident surface at the outer circumferential portion 53B is R2B, the relationship shown in formula (1) holds.

[0061] R2A ≠ R2B (1) In addition, when viewed in the optical axis direction of the first laser light LB1 and the second laser light LB2 directed from the collimation lens 52 to the focus lens 53, that is, in the Z direction in the example shown in Fig. 6, the outer circumferential portion 52B of the collimation lens 52 is disposed so as to surround the central portion 52A on the inside. Also, the outer circumferential portion 53B of the focus lens 53 is disposed so as to surround the central portion 53A on the inside. However, the outer circumferential portion 52B is continuous with the central portion 52A, and the outer circumferential portion 53B is continuous with the central portion 53A.

[0062] 6, the first laser light LB1 guided to the first core 41 disposed at the axial center of the optical fiber 40 passes through the central portions 52A and 53A. On the other hand, the second core 43 disposed on the outer periphery side of the first core 41 with the first cladding 42 in between is ring-shaped in cross section. For this reason, the second laser light LB2 guided to the second core 43 passes through the outer periphery portions 52B and 53B that surround the central portions 52A and 53A on the inside, respectively.

[0063] As shown in formula (1), the radius of curvature R2B of the light incident surface at the outer circumferential portion 53B of the focus lens 53 is different from the radius of curvature R2A of the light incident surface at the central portion 53A.

[0064] When the first laser light LB1 and the second laser light LB2 are simultaneously irradiated from the laser processing head 50 toward the workpiece 90, they are affected by chromatic aberration when they pass through the collimation lens 52 and the focus lens 53. If the collimation lens 52 and the focus lens 53 are spherical lenses, the chromatic aberration causes the focusing position of the first laser light LB1 and the focusing position of the second laser light LB2 to differ on the processing surface 90A of the workpiece 90 or in the vicinity of the processing surface 90A.

[0065] Therefore, as shown in this embodiment, in focus lens 53, radius of curvature R2B at outer circumferential portion 53B is made different from radius of curvature R2A at central portion 53A.

[0066] By doing this, the difference in refractive index at each lens that depends on the wavelength difference between the first laser light LB1 and the second laser light LB2 can be canceled, and the first laser light LB1 and the second laser light LB2 can be focused at the same focusing position.

[0067] Furthermore, when the focusing positions of the first laser light LB1 and the second laser light LB2 are different from the installation position, the collimation lens 52 is moved along the Z direction as described later. In this manner, it is possible to reduce the influence of the optical path length difference of the laser light generated when the first laser light LB1 and the second laser light LB2 are scanned by the first galvanometer mirror 55B and the second galvanometer mirror 56B, and to focus the first laser light LB1 and the second laser light LB2 at the same focusing position.

[0068] In addition, in a lens that does not perform chromatic aberration correction, the focusing position of light with a short wavelength, in this case the second laser light LB2, is closer to the focus lens 53 than the focusing position of the first laser light LB1. Also, since the second laser light LB2 passes through the outer periphery side of each lens than the first laser light LB1, the focusing position of the second laser light LB2 is even closer to the focus lens 53.

[0069] On the other hand, in the optical fiber 40 having the structure shown in FIG. 2, the numerical aperture of the second laser light LB2 guided by the second core 43, i.e., the maximum emission angle of the second laser light LB2 emitted from the optical fiber 40, is larger than the numerical aperture of the first laser light LB1 guided by the first core 41. Therefore, the optical path length from the emission end 40B of the optical fiber 40 to the focusing position is longer for the second laser light LB2 than for the first laser light LB1. This acts in the direction in which the focusing position of the second laser light LB2 approaches the processing surface 90A of the workpiece 90. In addition, the difference in the optical path length also depends on the size of each component inside the laser processing head 50.

[0070] The ratio between the radius of curvature R2B and the radius of curvature R2A is appropriately set in consideration of the various factors described above.

[0071] As described later, when the radius of curvature of the light exit surface at the central portion 52A of the collimation lens 52 is R1A and the radius of curvature of the light exit surface at the outer circumferential portion 52B is R1B, the radius of curvature R1B may be made different from the radius of curvature R1A.

[0072] The reflecting mirror 54 reflects the first laser beam LB1 and the second laser beam LB2, which have passed through the focus lens 53, in the Y direction toward the first galvanometer mirror 55B.

[0073] The first optical scanner 55 is composed of a first galvanometer motor 55A and a first galvanometer mirror 55B. The first galvanometer mirror 55B is connected to the rotation shaft of the first galvanometer motor 55A and rotates together with the rotation of the first galvanometer motor 55A. The rotation shaft of the first galvanometer motor 55A extends in the Z direction and rotates in the clockwise or counterclockwise direction within a predetermined angle range.

[0074] The first laser light LB1 and the second laser light LB2 reflected by the reflection mirror 54 are reflected by the first galvanometer mirror 55B and travel in the X direction toward the second galvanometer mirror 56B. In addition, the first galvanometer mirror 55B also rotates in a clockwise or counterclockwise direction within a predetermined angle range as the first galvanometer motor 55A rotates. By periodically switching the rotation direction of the first galvanometer motor 55A, the first laser light LB1 and the second laser light LB2 reflected by the first galvanometer mirror 55B are scanned back and forth in the Y direction on the processing surface 90A of the workpiece 90. The scanning amplitude of the first laser light LB1 and the second laser light LB2 on the processing surface 90A depends on the rotation angle range of the first galvanometer motor 55A.

[0075] The second optical scanner 56 is composed of a second galvanometer motor 56A and a second galvanometer mirror 56B. The second galvanometer mirror 56B is connected to the rotation shaft of the second galvanometer motor 56A and rotates together with the rotation of the second galvanometer motor 56A. The rotation shaft of the second galvanometer motor 56A extends in the Y direction and rotates in the clockwise or counterclockwise direction within a predetermined angle range.

[0076] The first laser light LB1 and the second laser light LB2 reflected by the first galvanometer mirror 55B are further reflected by the second galvanometer mirror 56B and travel in the Z direction toward the light exit port 51B. In addition, the second galvanometer mirror 56B also rotates clockwise or counterclockwise within a predetermined angle range as the second galvanometer motor 56A rotates. By periodically switching the rotation direction of the second galvanometer motor 56A, the first laser light LB1 and the second laser light LB2 reflected by the second galvanometer mirror 56B are scanned back and forth in the X direction on the processing surface 90A of the workpiece 90. The scanning amplitude of the first laser light LB1 and the second laser light LB2 on the processing surface 90A depends on the rotation angle range of the second galvanometer motor 56A.

[0077] By appropriately operating the first optical scanner 55 and the second optical scanner 56 according to a control signal from the control unit 80, the first laser light LB1 and the second laser light LB2 can be scanned along a desired trajectory on the processing surface 90A of the workpiece 90. This makes it easy to perform laser processing along the processing line even if the processing line has a complex shape.

[0078] <3-2: Configuration of optical component movement mechanism> Fig. 7A is a side view of the optical component moving mechanism, Fig. 7B is an exploded perspective view of the optical component moving mechanism, and Fig. 7C is a cross-sectional view taken along line VIIC-VIIC in Fig. 7A.

[0079] As shown in FIGS. 7A to 7C, optical component moving mechanism 57 has a third galvanometer motor 57A, a first base 57B, a second base 57D, a screw ring holder 57C, a first gear 57E, and a second gear 57F.

[0080] The screw ring holder 57C and the second gear 57F are integrally provided, and the teeth of the second gear 57F protrude in the radial direction from the outer circumferential surface of the screw ring holder 57C. As shown in Figs. 7B and 7C, the screw ring holder 57C is cylindrical, and the screw ring 57G is accommodated inside the screw ring holder 57C. The outer circumferential surface of the screw ring 57G is arranged to mesh with a screw groove (not shown) provided on the inner circumferential surface of the screw ring holder 57C. That is, the screw ring 57G and the screw ring holder 57C form a kind of ball screw. The collimation lens 52 is arranged inside the screw ring 57G.

[0081] In addition, O-rings 57H are provided on both sides in the Z direction on the outer surface of the screw ring holding portion 57C, sandwiching the second gear 57F, to seal between the screw ring holding portion 57C and the first base 57B, and between the screw ring holding portion 57C and the second base 57D.

[0082] The third galvanometer motor 57A is attached to the housing 51, and a first gear 57E is attached to the rotation shaft of the third galvanometer motor 57A. The rotation shaft of the third galvanometer motor 57A extends in the Z direction. The first gear 57E and the second gear 57F mesh with each other.

[0083] When the third galvanometer motor 57A rotates in response to a control signal from the control unit 80, the first gear 57E also rotates in the same direction as the rotation axis of the third galvanometer motor 57A around the rotation axis of the third galvanometer motor 57A. In addition, the second gear 57F meshing with the first gear 57E rotates in the opposite direction to the first gear 57E, and in accordance with this rotation, the screw ring holder 57C also rotates in the same direction as the second gear 57F.

[0084] As described above, the screw ring holder 57C and the screw ring 57G form a ball screw. Therefore, as the screw ring holder 57C rotates, the screw ring 57G and the collimation lens 52 housed inside the screw ring 57G move along the Z direction. For example, when the third galvanometer motor 57A rotates clockwise, the collimation lens 52 moves upward along the Z direction.

[0085] When the rotation direction of the third galvanometer motor 57A becomes counterclockwise, the rotation directions of the first gear 57E, the second gear 57F and the screw ring holder 57C also reverse, and the collimation lens 52 moves downward along the Z direction.

[0086] As described above, the collimation lens 52 moves upward or downward along the Z direction by rotating the third galvanometer motor 57A in the clockwise or counterclockwise direction according to a control signal from the control unit 80. The moving speed and moving amount of the collimation lens 52 are determined by the rotation speed and the rotation amount of the rotation shaft of the third galvanometer motor 57A, respectively. Note that when the third galvanometer motor 57A rotates in the clockwise direction, the collimation lens 52 may move downward along the Z direction.

[0087] Note that, instead of the third galvanometer motor 57A, another type of actuator, such as a linear motor, may be used. The collimation lens 52 may be configured to move up and down along the Z direction by operating the actuator.

[0088] <3-3: Relationship between the arrangement of each optical component of the laser processing head and the focusing position of the laser light> FIG. 8 is a schematic diagram showing the layout relationship of optical components inside the laser processing head.

[0089] As shown in FIG. 8, inside the housing 51 of the laser processing head 50, a collimation lens 52, a focus lens 53, and first and second galvanometer mirrors 55B, 56B are arranged in this order from the emission end 40B of the optical fiber 40 along the optical paths of the first and second laser lights LB1, LB2.

[0090] As described above, the collimation lens 52 is movable in the Z direction, that is, along the optical paths of the first laser light LB1 and the second laser light LB2. The focus lens 53 is an aspheric lens in which chromatic aberration is corrected.

[0091] Here, the focal length of collimation lens 52 is e1, and the focal length of focus lens 53 is e2. In particular, when no adjustment is required, the focusing positions of the first laser light LB1 and the second laser light LB2 are positioned at a distance e2 from the center of focus lens 53.

[0092] Here, consider a case where it is desired to move the focusing positions of the first laser beam LB1 and the second laser beam LB2 closer to the processing surface 90A by Δe2 along the Z direction. In this case, the optical component moving mechanism 57 is operated to move the collimation lens 52 upward by Δe1. If Δe1 is the vertical movement amount and Δe2 is the focusing position movement amount, the vertical movement amount Δe1 and the focusing position movement amount Δe2 satisfy the relationship shown in formula (2).

[0093] Δe1=(Δe2 / α 2 )-t (2) Here, α is the optical magnification of the optical system provided in the laser processing head 50, and the optical magnification α satisfies the relationship shown in equation (3).

[0094] α = e2 / e1 (3) Furthermore, t is a fine adjustment parameter that is set in consideration of variations in the optical characteristics of each lens in actual control.

[0095] In addition, when it is desired to move the focusing position of the first laser light LB1 and the second laser light LB2 away from the processing surface 90A by Δe2 along the Z direction, the optical component moving mechanism 57 is operated to move the collimation lens 52 downward by Δe1.

[0096] [4: About hybrid laser processing method] Fig. 9 is a diagram showing the wavelength dependence of light absorptance in various metals Fig. 10 is a schematic diagram showing the power density distribution of the first laser beam and the second laser beam in the vicinity of the output end of the optical fiber.

[0097] In general, when a metal is irradiated with light, the proportion of the light absorbed by the metal, i.e., the light absorptance, varies depending on the wavelength of the light. Furthermore, the wavelength dependency of the light absorptance varies greatly depending on the metal material.

[0098] For example, in iron and nickel, the optical absorptance increases as the wavelength becomes shorter, but the degree of change in optical absorptance with respect to wavelength is gradual, as shown in Fig. 6. Taking iron as an example, the optical absorptance at the wavelength λ1 (=975 nm) of the first laser light LB1 is 40%, and the optical absorptance at the wavelength λ2 (=450 nm) of the second laser light LB2 is about 45%.

[0099] On the other hand, in copper, the optical absorptance increases rapidly when the wavelength enters the visible light wavelength range. As shown in Fig. 9, the optical absorptance of the first laser light LB1 at the wavelength λ1 is less than 10%, while the optical absorptance of the second laser light LB2 at the wavelength λ2 increases to about 60%.

[0100] For this reason, when the workpiece 90 is a plate material made of copper, it is more advantageous to perform laser processing using the second laser light LB2. On the other hand, the power of the second laser light LB2, which is usually blue light, is lower than the power of the first laser light LB1, which is near-infrared light. This is due to the difference in performance between the laser light source that emits the second laser light LB2 and the laser light source that emits the first laser light LB1. When the laser light source that emits the second laser light LB2 is composed of a semiconductor laser element, this difference in performance becomes particularly large. If the number of laser light sources included in the second laser oscillator 20 is increased, this difference in performance can be reduced, but the second laser oscillator 20 will become larger and the input power will become larger.

[0101] Therefore, as shown in Patent Documents 1 to 3, a so-called hybrid laser processing method has been adopted in which a visible laser beam and an infrared laser beam are combined and irradiated onto the workpiece 90.

[0102] Using the laser processing apparatus 200 of this embodiment, the first laser light LB1 and the second laser light LB2 are simultaneously irradiated onto the workpiece 90, which is a copper plate material. In this case, the second laser light LB2 is irradiated coaxially with the first laser light LB1 on the processing surface 90A of the workpiece 90. Also, as shown in FIG. 10, the power distribution of the first laser light LB1 emitted from the emission end 40B of the optical fiber 40 has a single-peaked peak. Also, the second laser light LB2 has a peak lower than the first laser light LB1 outside the first laser light LB1 so as to surround the peak of the first laser light LB1 on the inside. This is because the second core 43 is arranged coaxially with the first core 41 and is provided in a ring shape.

[0103] Therefore, the second laser light LB2 is focused at the same focusing position as the first laser light LB1 along the traveling direction from the laser processing head 50 toward the workpiece 90. On the other hand, on the processing surface 90A of the workpiece 90, the irradiation spot diameter D2 (see FIG. 5) of the second laser light LB2 is larger than the irradiation spot diameter D1 (see FIG. 5) of the first laser light LB1. For example, when the irradiation spot diameter D1 is about 50 μm, the irradiation spot diameter D2 is about 200 μm to 300 μm.

[0104] In this manner, the workpiece 90 made of copper is heated by the second laser light LB2 having a high light absorption rate. When the workpiece 90 is heated to near its melting point by irradiation with the second laser light LB2, the light absorption rate of the first laser light LB1 in the workpiece 90 increases significantly, so that the workpiece 90 is laser-machined smoothly in a short time by the high-power first laser light LB1.

[0105] Depending on the material and thickness of the workpiece 90 and the processing mode, the laser processing may be performed using only the first laser beam LB1, or the laser processing may be performed using only the second laser beam LB2.

[0106] [Effects, etc.] As described above, the laser processing head 50 according to this embodiment includes a housing 51 and a plurality of optical components disposed inside the housing 51. The housing 51 has a fiber connection port 51A and a light emission port 51B, and the optical fiber 40 is connected to the fiber connection port 51A.

[0107] The optical fiber 40 has at least a first core 41 provided at the axis, and a second core 43 provided radially outside the first core 41 and coaxially with the first core 41. A first laser light LB1 having a first wavelength (wavelength λ1) is guided to the first core 41, and a second laser light LB2 having a second wavelength (wavelength λ2) shorter than the first wavelength is guided to the second core 43.

[0108] At least one of the first laser beam LB1 and the second laser beam LB2 is emitted toward the workpiece 90 from the light emission port 51B.

[0109] The multiple optical components include at least a collimation lens 52 and a focus lens (second focus lens) 53. The collimation lens 52 collimates the first laser light LB1 or the second laser light LB2, or both, guided into the inside of the housing 51 by the optical fiber 40. The focus lens 53 focuses the first laser light LB1 and the second laser light LB2 collimated by the collimation lens 52 to the same focusing position on the processing surface 90A of the workpiece 90 or in the vicinity of the processing surface 90A.

[0110] The collimation lens 52 and the focus lens 53 are each an aspheric lens. The first laser light LB1 passes through central portions 52A and 53A of the collimation lens 52 and the focus lens 53, respectively, and the second laser light LB2 passes through peripheral portions 52B and 53B of the collimation lens 52 and the focus lens 53, respectively.

[0111] The focus lens 53 has chromatic aberration corrected so that the first laser light LB1 and the second laser light LB2 are focused at the same focusing position on the processing surface 90A of the workpiece 90 or in the vicinity of the processing surface 90A.

[0112] Specifically, in the focus lens 53, the radius of curvature R2B of the outer circumferential portion 53B is made different from the radius of curvature R2A of the central portion 53A, thereby correcting chromatic aberration.

[0113] In addition, the laser processing head 50 further includes an optical component moving mechanism 57 that moves the collimation lens 52 in the Z direction.

[0114] The optical components further include a first galvanometer mirror (first mirror) 55B and a second galvanometer mirror (second mirror) 56B. Inside the housing 51, the first galvanometer mirror 55B and the second galvanometer mirror 56B are disposed at positions closer to the light exit port 51B than the collimation lens 52 and the focus lens 53.

[0115] The first galvanometer mirror 55B is configured to scan the incident first laser light LB1 or second laser light LB2, or both, in the Y direction. The second galvanometer mirror 56B is configured to scan the incident first laser light LB1 or second laser light LB2, or both, in the X direction.

[0116] By configuring the laser processing head 50 in this way, the first laser light LB1 and the second laser light LB2, which are guided by the optical fiber 40, which is a multicore fiber, and have different wavelengths, can be focused to the same focusing position. In addition, a focusing position adjustment mechanism is provided for chromatic aberration correction, and the labor required to adjust the focusing position of one laser light to match the other laser light is not required.

[0117] Furthermore, according to this embodiment, there is no need to provide optical fibers for guiding laser light of different wavelengths, which makes it possible to prevent the laser processing head 50 from becoming large.

[0118] In addition, optical fibers deteriorate over long periods of use and must be replaced periodically. Although this depends on the power of the laser light used in the laser processing and the laser processing time, it is usually necessary to replace the optical fiber every one to two years.

[0119] According to this embodiment, the first laser light LB1 and the second laser light LB2, which have different wavelengths, are guided to the laser processing head 50 by a single optical fiber 40. This makes it possible to reduce the initial cost of installing the optical fiber and the running cost of replacing the optical fiber, compared to conventional laser processing heads that connect two optical fibers.

[0120] In addition, when the first optical scanner 55 and the second optical scanner 56 are operated to irradiate the first laser light LB1 and the second laser light LB2 to draw a desired trajectory on the processing surface 90A of the workpiece 90, a difference in optical path length may occur between the end and center of the trajectory. For example, even if the focusing positions of the first laser light LB1 and the second laser light LB2 are on the processing surface 90A at the center of the trajectory, the focusing positions may shift along the Z direction at the end of the trajectory. Depending on the amount of this shift, there is a risk of adversely affecting the laser processing quality.

[0121] For this reason, in conventional configurations, this problem has been solved by using an fθ lens, but as mentioned above, an fθ lens cannot simultaneously correct chromatic aberration.

[0122] On the other hand, according to the present embodiment, the optical component moving mechanism 57 is operated to move the collimation lens 52 along the Z direction. In this way, the shift of the focusing position due to the difference in the optical path length can be corrected, and further, the chromatic aberration of the first laser light LB1 and the second laser light LB2 having different wavelengths can be corrected. As a result, when the first and second optical scanners 55, 56 irradiate the first laser light LB1 and the second laser light LB2 while scanning, the focusing positions of the first laser light LB1 and the second laser light LB2 can be set to the same position in the Z direction over the entire irradiation range.

[0123] Furthermore, there is no need to use a telecentric lens such as an fθ lens to match the focusing position on the processing surface at the end and center of the scanning trajectory, and this can prevent an increase in the number of optical components inside the laser processing head 50. Furthermore, the focusing positions of the first laser light LB1 and the second laser light LB2 can be made the same in the Z direction over the entire irradiation range without using optical components with a complex structure such as an fθ lens. This allows the cost of the laser processing head 50 to be reduced.

[0124] It is preferable that the first laser light LB1 is in the near-infrared or infrared wavelength range, and the second laser light LB2 is in the visible wavelength range. In this way, a laser light in a wavelength range that can obtain high power can be used as the first laser light LB1 that passes through the central parts 52A and 53A of the collimation lens 52 and the focus lens 53, respectively. As a wavelength range that is often actually used in laser processing, it is preferable that the wavelength λ1 of the first laser light LB1 is 800 nm or more and 1200 nm or less.

[0125] Moreover, the second laser light LB2 is irradiated around the first laser light LB1 on the processing surface 90A of the workpiece 90. As described above, when laser processing the workpiece 90 made of a material such as copper that has low light absorption rate for near-infrared or infrared light, the wavelength λ2 of the second laser light LB2 is preferably in the wavelength range of visible light or near-ultraviolet light that has high light absorption rate for the material. In other words, the wavelength λ2 of the second laser light LB2 is preferably 380 nm or more and 660 nm or less.

[0126] In addition, it is preferable that the optical characteristics of the optical fiber 40 connected to the laser processing head 50 are adjusted so that the first core 41 has a minimum or extremely small transmission loss of the first laser light LB1, and the second core 43 has a minimum or extremely small transmission loss of the second laser light LB2.

[0127] When laser beams of different wavelengths are guided to one core of the optical fiber 40, if the optical characteristics of the core are specified so that the transmission loss for one wavelength of light is minimal or extremely small, the transmission loss for the other wavelength of light becomes large. This tendency becomes particularly noticeable when the cable length of the optical fiber 40 becomes long. When high-power laser beams are required, such as in laser processing, large transmission loss may lead to heat generation or damage to the optical fiber 40.

[0128] On the other hand, according to the present embodiment, the first laser light LB1 and the second laser light LB2 are guided to the first core 41 and the second core 43, respectively, of the optical fiber 40. By appropriately setting the optical characteristics of the first core 41 and the second core 43, it is possible to reduce the loss of each of the first laser light LB1 and the second laser light LB2 transmitted to the optical fiber 40, and it is possible to perform laser processing of the workpiece 90 with the desired power.

[0129] The laser processing apparatus 200 according to this embodiment at least includes a laser processing head 50, a first laser oscillator 10, a second laser oscillator 20, an optical coupler 30, and an optical fiber 40.

[0130] The first laser oscillator 10 generates a first laser light LB1, and the second laser oscillator 20 generates a second laser light LB2.

[0131] The optical coupler 30 receives the first laser light LB1 and the second laser light LB2, and causes the first laser light LB1 to enter the first core 41 and the second laser light LB2 to enter the second core 43. When only the first laser light LB1 is generated, the optical coupler 30 causes the first laser light LB1 to enter the first core 41. When only the second laser light LB2 is generated, the optical coupler 30 causes the second laser light LB2 to enter the second core 43.

[0132] The optical fiber 40 is connected to the optical coupler 30 and the laser processing head 50 , and guides at least one of the first laser light LB1 and the second laser light LB2 from the optical coupler 30 to the laser processing head 50 .

[0133] By configuring the laser processing apparatus 200 in this manner, when laser processing the workpiece 90 using a first laser light LB1 and a second laser light LB2 having different wavelengths, the first laser light LB1 and the second laser light LB2 can be focused to the same focusing position without providing a focusing position adjustment mechanism or the like.

[0134] When the first laser beam LB1 and the second laser beam LB2 are simultaneously irradiated onto the workpiece 90, the second laser beam LB2 is irradiated coaxially with the first laser beam LB1 on the processing surface 90A of the workpiece 90. Furthermore, the irradiation spot diameter D2 of the second laser beam LB2 is larger than the irradiation spot diameter D1 of the first laser beam LB1.

[0135] In this way, when laser processing the workpiece 90 made of a material with low light absorptivity for the first laser beam LB1, the workpiece 90 can be heated to near its melting point by being absorbed by the second laser beam LB2. In addition, since the light absorptivity for the first laser beam LB1 increases rapidly in the heated portion, the workpiece 90 can be processed smoothly in a short time using the high-power first laser beam LB1.

[0136] Moreover, by making the irradiation spot diameter D2 larger than the irradiation spot diameter D1, the first laser light LB1 can be irradiated only to the portion heated by the second laser light LB2. This makes it possible to prevent the high-power first laser light LB1 from being directly irradiated to the workpiece 90 whose temperature has not risen sufficiently. If the high-power first laser light LB1 is irradiated to the workpiece 90 whose temperature has not risen sufficiently, the molten portion of the workpiece 90 may bump due to a sudden rise in temperature, causing spattering. According to this embodiment, the occurrence of such spattering can be suppressed.

[0137] The laser processing apparatus 200 further includes a control unit 80 that controls the operation of at least the optical coupler 30 .

[0138] The optical coupler 30 has at least a reflecting mirror 32, an actuator 33, and a dichroic mirror 34. The reflecting mirror 32 reflects the incident second laser light LB2 toward an incident end 40A of the optical fiber 40.

[0139] The actuator 33 is attached to the reflecting mirror 32 and adjusts the angle of the reflecting mirror 32 based on a control signal from the control unit 80 so that the second laser light LB2 is incident on the second core 43.

[0140] The dichroic mirror 34 is disposed on the optical path of the second laser light LB2 traveling from the reflecting mirror 32 toward the optical fiber 40, and on the optical path of the first laser light LB1. The dichroic mirror 34 is configured to transmit the incident second laser light LB2 and to reflect the incident first laser light LB1.

[0141] The first laser light LB1 reflected by the dichroic mirror 34 is incident on the first core 41 at the incident end 40A of the optical fiber 40. The second laser light LB2 transmitted through the dichroic mirror 34 is incident on the second core 43 at the incident end 40A of the optical fiber 40.

[0142] By configuring the optical coupler 30 in this manner, it is possible to make the first laser light LB1 enter the first core 41 and the second laser light LB2 enter the second core 43 reliably with a simple configuration.

[0143] <Modification> Fig. 11 is a schematic diagram showing the arrangement of optical components inside a laser processing head according to a modified example. Fig. 12 is a schematic diagram showing another arrangement of optical components inside a laser processing head according to a modified example. Fig. 13 is a schematic diagram showing yet another arrangement of optical components inside a laser processing head according to a modified example. For convenience of explanation, in Fig. 11 and each of the drawings shown thereafter, the same reference numerals are used for the same parts as those in the first embodiment, and detailed explanations are omitted.

[0144] In the first embodiment, the lens moved along the Z direction is the collimation lens 52. Also, the focus lens 53 is a lens in which chromatic aberration is corrected by making the radii of curvature of the central portion 53A through which the first laser light LB1 passes and the peripheral portion 53B through which the second laser light LB2 passes different from each other.

[0145] On the other hand, as shown in this modified example, the configuration in which chromatic aberration is corrected using a first laser light LB1 and a second laser light LB2 having different wavelengths while these laser lights are focused at the same focusing position when scanning the processing surface 90A of the workpiece 90 is not limited to the example shown in embodiment 1.

[0146] In this specification, a lens configured to be movable inside the housing 51 in the Z direction, more precisely, along the traveling direction of the first laser light LB1 and the second laser light LB2, may be referred to as a first lens, and a lens with corrected chromatic aberration may be referred to as a second lens. The optical component moving mechanism 57 holds the first lens and moves the first lens upward or downward along the Z direction. That is, in the example shown in the first embodiment, the collimation lens 52 is the first lens, and the focus lens 53 is the second lens.

[0147] 11, a beam expander 58 may be provided between the collimation lens 52 and the focus lens 53. The beam expander 58 expands the first laser light LB1 or the second laser light LB2, or both, that have passed through the beam expander 58 in a direction perpendicular to the Z direction.

[0148] 11, in the collimation lens 52, the central portion 52A through which the first laser light LB1 passes and the outer peripheral portion 52B through which the second laser light LB2 passes are made to have different radii of curvature, thereby correcting chromatic aberration. In addition, the optical component moving mechanism 57 holds the beam expander 58 and moves the beam expander 58 along the Z direction. In addition, the focus lens 53 is composed of a pair of a first sub-lens 531 and a second sub-lens 532.

[0149] The focal length of the beam expander 58 is f1, the focal length of the first sub-lens 531 is f2, and the focal length of the second sub-lens 532 is f4. The distance between the beam expander 58 and the first sub-lens 531 along the traveling direction of the first laser light LB1 and the second laser light LB2 is d1, and the distance between the first sub-lens 531 and the second sub-lens 532 along the traveling direction of the first laser light LB1 and the second laser light LB2 is d2. The distance from the second sub-lens 532 to the focusing position along the traveling direction of the first laser light LB1 and the second laser light LB2 is F.

[0150] In this case, d1, d2, f1, f2, f4, and F satisfy the relationships shown in the formulas (4) to (8), where t is the fine-tuning parameter shown in the formula (3).

[0151] d1=((q-sF) / (rF-p))-t ···(4) p = -f2f4 + f4d2 (5) q=f1f2f4-f1f4d2-f2f4d2...(6) r = -f2 -f4 + d2 (7) s=f1f2+f1f4+f2f4-f1d2-f2d2...(8) As is clear from formula (4), when the focusing positions of the first laser light LB1 and the second laser light LB2 are shifted, that is, when the distance F is changed, the optical component moving mechanism 57 is operated to change the distance d1 between the beam expander 58 and the first sub-lens 531. That is, in the example shown in FIG. 11, the beam expander 58 is the first lens, and the collimation lens 52 is the second lens. In addition, the focus lens 53 composed of the first sub-lens 531 and the second sub-lens 532 focuses the first laser light LB1 and the second laser light LB2 expanded by the beam expander 58 so that they are at the same focusing position on the processing surface 90A of the workpiece 90 or in the vicinity of the processing surface 90A.

[0152] The distance d1 is calculated by the control unit 80 based on the amount of movement of the optical component moving mechanism 57 in the Z direction with reference to the initial position of the beam expander 58. The distance F is calculated, for example, based on the result of placing a beam detector (not shown) on a virtual processing surface and measuring the received light intensity or beam profile.

[0153] 12 and 13, a chromatic aberration correction lens 59 may be provided near the exit end 40B of the optical fiber 40. The chromatic aberration correction lens 59 is an aspheric lens having different radii of curvature between a central portion through which the first laser light LB1 passes and an outer periphery through which the second laser light LB2 passes.

[0154] FIG. 12 shows an example in which a chromatic aberration correction lens 59 is arranged between the output end 40B of the optical fiber 40 and the collimation lens 52 in comparison with the arrangement of the optical components shown in FIG. 8. In the example shown in FIG. 12, the focus lens 53 is not an aspheric lens and is not structured to correct chromatic aberration. In addition, FIG. 13 shows an example in which a chromatic aberration correction lens 59 is arranged between the output end 40B of the optical fiber 40 and the collimation lens 52 in comparison with the arrangement of the optical components shown in FIG. 11. In the example shown in FIG. 13, the collimation lens 52 is not an aspheric lens and is not structured to correct chromatic aberration.

[0155] 12 and 13, by providing a chromatic aberration correction lens 59 near the emission end 40B of the optical fiber 40, it becomes possible to perform chromatic aberration correction before the first laser light LB1 and the second laser light LB2 have a predetermined spread. This makes it possible to perform chromatic aberration correction of the first laser light LB1 and the second laser light LB2 more effectively than in the examples shown in Figs. 8 and 11.

[0156] 11 to 13, the same effects as those of the configuration shown in the first embodiment can be achieved. That is, the first laser light LB1 and the second laser light LB2, which are guided by the optical fiber 40, which is a multi-core fiber, and have different wavelengths, can be focused to the same focusing position. Also, a focusing position adjustment mechanism is provided for chromatic aberration correction, and the labor required to adjust the focusing position of one laser light to match the other laser light is not required.

[0157] In addition, there is no need to provide optical fibers for guiding laser light for each different wavelength, which prevents the laser processing head 50 from becoming large. Also, compared to conventional laser processing heads that connect two optical fibers, the initial cost of installing optical fibers and the running cost of replacing optical fibers can be reduced.

[0158] Furthermore, when the first and second optical scanners 55, 56 are used to irradiate the first laser light LB1 and the second laser light LB2 while scanning, the focusing positions of the first laser light LB1 and the second laser light LB2 can be made to be the same position in the Z direction throughout the entire irradiation range.

[0159] (Embodiment 2) [Configuration and operation of telescope barrel components] Fig. 14 is a schematic diagram showing a method for adjusting the focusing positions of the first laser light and the second laser light according to embodiment 2. Fig. 15 is a perspective view of a collimation lens held in a lens barrel part. Fig. 16A is a diagram showing temperature distributions of the lens barrel part and the collimation lens after a heater is operated. Fig. 16B is a diagram showing temperature distributions of the collimation lens after a heater is operated.

[0160] 14 and 15, the collimation lens 52 in this embodiment is circular when viewed in the Z direction, and a cylindrical lens barrel part 60 abuts against the outer periphery of the collimation lens 52 to hold the collimation lens 52. A heater 60A is provided inside the lens barrel part 60. Although not shown, the heater 60A is provided continuously around the outer periphery of the lens barrel part 60.

[0161] In this embodiment, a heater 60A provided in the lens barrel part 60 is operated by a control signal from the control unit 80 to heat the lens barrel part 60, thereby applying a temperature gradient to the collimation lens 52. In this way, a refractive index difference is generated inside the collimation lens 52, the chromatic aberration of the first laser light LB1 and the second laser light LB2 are corrected, and the focusing positions of the first laser light and the second laser light in the Z direction are adjusted to be the same. This will be further described.

[0162] As shown in the left side of FIG. 14, it is assumed that the focusing position of the first laser light LB1 is located above the focusing position of the second laser light LB2 along the Z direction. In this case, when the heater 60A is operated to heat the lens barrel part 60, the temperature of the lens barrel part 60 rises as shown in FIG. 16A. Note that in FIGS. 16A and 16B, the darker the color, the higher the temperature, and the lighter the color, the lower the temperature. In the example shown in FIGS. 16A and 16B, the temperature range is about several degrees Celsius, but is not particularly limited to this. Also, even if the set temperature of the heater 60A is the same, this temperature range differs depending on the size of the lens barrel part 60 and the collimation lens 52, and their respective heat capacities. Therefore, the set temperature of the heater 60A is not particularly limited to the above-mentioned temperature range.

[0163] Heating the lens barrel part 60 also increases the temperature of the collimation lens 52 held by the lens barrel part 60. In this case, the temperature of the outer periphery of the collimation lens 52 in contact with the lens barrel part 60 is the highest, and the temperature increase rate decreases toward the center of the collimation lens 52. In other words, a temperature gradient is imparted to the collimation lens 52 such that the temperature decreases from the outer periphery toward the center, in other words, in the direction perpendicular to the Z direction.

[0164] When such a temperature gradient is applied to the collimation lens 52, a difference in refractive index occurs between the outer peripheral portion 52B and the central portion 52A. Specifically, the refractive index of the outer peripheral portion 52B, which has a higher temperature than the central portion 52A, is greater than that of the central portion. As a result, the light incident on the outer peripheral portion 52B is bent more toward the center, i.e., toward the optical axis of the laser light, than before the heater 60A was operated, which is a phenomenon known as the thermal lens effect.

[0165] Due to this thermal lens effect, the second laser light LB2 passing through the outer circumferential portion 52B of the collimation lens 52 is strongly bent toward its optical axis, so that the focusing position shifts upward along the Z direction. Since the temperature of the central portion 52A of the collimation lens 52 also rises, the focusing position of the first laser light LB1 also shifts upward along the Z direction. However, since the temperature of the outer circumferential portion 52B is higher than that of the central portion 52A, the shift amount of the focusing position of the second laser light LB2 becomes larger than the shift amount of the focusing position of the first laser light LB1.

[0166] By taking advantage of this, by appropriately adjusting the temperature of the barrel component 60, the second laser light LB2 passing through the outer circumferential portion 52B of the collimation lens 52 can be strongly refracted, and its focusing position along the Z direction can be adjusted to be the same as the focusing position of the first laser light LB1.

[0167] In this embodiment, the collimation lens 52 may be the first lens described in the second embodiment, and the focus lens 53 may be the second lens. That is, the collimation lens 52 is configured to be movable along the Z direction by the optical component moving mechanism 57. The focus lens 53 is an aspheric lens, and corrects the chromatic aberration of the first laser light LB1 and the second laser light LB2. If the correction of the chromatic aberration by the focus lens 53 is insufficient, the heater 60A of the lens barrel component 60 is operated to adjust the focusing position of the second laser light LB2 to be the same as the focusing position of the first laser light LB1.

[0168] It should be noted that the optical component held in the lens barrel component 60 is not particularly limited to the collimation lens 52 .

[0169] Fig. 17 is a schematic diagram showing an example of the temperature distribution of the optical components before temperature adjustment and the difference in the focusing positions of the first laser light and the second laser light. Fig. 18 is a schematic diagram showing an example of the temperature distribution of the optical components after temperature adjustment and the difference in the focusing positions of the first laser light and the second laser light.

[0170] Although an example is shown here in which the focus lens 53 is held by the lens barrel part 60, for example, the beam expander 58 or the chromatic aberration correction lens 59 shown in the modified example may be held by the lens barrel part 60. In other words, any of the optical components inside the housing 51, excluding the first galvanometer mirror 55B, the second galvanometer mirror 56B, and a protective glass (not shown), may be held by the lens barrel part 60.

[0171] In the example shown in FIG. 17, similarly to the example shown in FIG. 14, the focusing position of the first laser light LB1 is located above the focusing position of the second laser light LB2 along the Z direction. Therefore, as described above, the heater 60A is operated to heat the lens barrel part 60. As a result, the second laser light LB2 passing through the outer peripheral part 53B of the focus lens 53 is strongly refracted, and the focusing position of the second laser light LB2 along the Z direction shifts upward. Furthermore, by appropriately adjusting the temperature of the lens barrel part 60, the focusing position of the second laser light LB2 can be adjusted to be the same as the focusing position of the first laser light LB1.

[0172] On the other hand, depending on the arrangement of the optical components in the laser processing head 50, the focusing position of the second laser light LB2 may be located higher in the Z direction than the focusing position of the first laser light LB1. In such a case, for example, instead of providing the heater 60A in the lens barrel component 60, a cooling unit 60B is provided to cool the lens barrel component 60.

[0173] Fig. 19 is a schematic diagram showing another example of the temperature distribution of the optical component before the temperature adjustment and the difference in the focusing position of the first laser light and the second laser light. Fig. 20 is a schematic diagram showing another example of the temperature distribution of the optical component after the temperature adjustment and the focusing position of the first laser light and the second laser light.

[0174] 19, as described above, the focusing position of the first laser light LB1 is located lower along the Z direction than the focusing position of the second laser light LB2. In this case, the cooling unit 60B is operated to cool the lens barrel part 60. In this manner, the outer periphery 53B of the focus lens 53 that is in contact with the lens barrel part 60 is cooled. As a result, a temperature gradient is imparted to the focus lens 53 such that the temperature decreases from the center toward the outer periphery, in other words, in the direction perpendicular to the Z direction.

[0175] As a result, refraction of the second laser light LB2 passing through the outer circumferential portion 53B of the focus lens 53 is weakened, and the focusing position of the second laser light LB2 along the Z direction shifts downward along the Z direction. Furthermore, by appropriately adjusting the temperature of the barrel component 60, the focusing position of the second laser light LB2 can be adjusted to be the same as the focusing position of the first laser light LB1.

[0176] As the cooling unit 60B, for example, a cooling element such as a Peltier element can be used. The cooling unit 60B may also be a water-cooled pipe. Usually, in order to cool the housing 51 and the like, the laser processing head 50 is provided with a water-cooled pipe (not shown), and temperature-controlled cooling water is circulated and supplied. A part of this cooling water may be supplied to the cooling unit 60B. In this case, too, the cooling water passes through the cooling unit 60B and then returns to the external chiller. There, the temperature is adjusted, and the water is then supplied again to the cooling unit 60B.

[0177] As described above, the laser processing head 50 according to this embodiment has the barrel part 60 for holding the optical component inside the housing 51. The barrel part 60 holds the optical component by contacting the outer periphery of the optical component. The barrel part 60 is configured to impart a temperature gradient to the optical component in a direction intersecting the Z direction, specifically, in a direction along the light receiving surface of the optical component.

[0178] According to this embodiment, by applying the above-mentioned temperature gradient to the optical component, the temperature of the outer periphery of the optical component through which the second laser light LB2 passes can be made different from the temperature of the central portion through which the first laser light LB1 passes. This generates a refractive index difference between the outer periphery and the central portion, and in particular, it is possible to change the traveling direction of the second laser light LB2 after passing through the optical component.

[0179] That is, when there is a difference in the focusing position along the Z direction between the first laser light LB1 and the second laser light LB2, an appropriate temperature gradient is applied to the optical components by the lens barrel component 60 according to the positional relationship of the respective focusing positions and the absolute value of the difference. This makes it possible to adjust the focusing position of the first laser light LB1 and the focusing position of the second laser light LB2 to the same position along the Z direction.

[0180] When the focusing position of the first laser light LB1 is located above the focusing position of the second laser light LB2 along the Z direction, the lens barrel part 60 is preferably configured to heat the optical components. Specifically, the lens barrel part 60 preferably has a heater 60A as a heating unit. The temperature of the lens barrel part 60 can be adjusted by controlling the heater 60A.

[0181] In this way, when the second laser light LB2 passes through the outer periphery of the optical component, it is strongly refracted, and the focusing position of the second laser light LB2 can be shifted upward along the Z direction. As a result, the focusing position of the first laser light LB1 and the focusing position of the second laser light LB2 can be adjusted to the same position along the Z direction.

[0182] Furthermore, when the focusing position of the first laser light LB1 is located above the focusing position of the second laser light LB2 along the Z direction, it is preferable that the barrel part 60 is configured to cool the optical parts. Specifically, it is preferable that the barrel part 60 has a cooling unit 60B. Note that the temperature of the barrel part 60 can be adjusted by controlling the cooling unit 60B. When the cooling unit 60B is a water-cooled tube, the temperature of the cooling water flowing through the water-cooled tube is adjusted.

[0183] In this way, when the second laser light LB2 passes through the outer periphery of the optical component, refraction is weakened, and the focusing position of the second laser light LB2 can be shifted downward along the Z direction. As a result, the focusing position of the first laser light LB1 and the focusing position of the second laser light LB2 can be adjusted to the same position along the Z direction.

[0184] The temperature of the lens barrel part 60 is calculated by the control unit 80 based on a signal measured by a temperature sensor (not shown) attached to the lens barrel part 60. For example, a thermocouple is used as the temperature sensor. Alternatively, a resistor may be used.

[0185] Furthermore, the lens barrel part 60 may simultaneously have the heater 60A and the cooling part 60B. In this way, regardless of the positional relationship between the focusing position of the first laser beam LB1 and the focusing position of the second laser beam LB2, the focusing positions along the Z direction can be set to the same position.

[0186] [Procedure for adjusting the focusing positions of the first laser beam and the second laser beam] Based on the above, a procedure for adjusting the focusing positions of the first laser light and the second laser light in this embodiment will be described.

[0187] 21 is a flow chart showing a procedure for adjusting the focusing positions of the first laser beam and the second laser beam, in which predetermined positions on the processing surface 90A of the workpiece 90 are set as the respective focusing positions.

[0188] First, the first laser oscillator 10 is operated to generate the first laser light LB1, and the first laser light LB1 is irradiated from the laser processing head 50 to the workpiece 90 while scanning the workpiece 90 within a predetermined irradiation range. Furthermore, the actual focusing position of the first laser light LB1 within the predetermined range (hereinafter referred to as the first focusing position) is confirmed (step S1).

[0189] The irradiation range corresponds to the irradiation range of the first laser beam LB1 and the second laser beam LB2 in actual laser processing. The first focusing position is confirmed by arranging a detection surface of a beam detector (not shown) in the above-mentioned irradiation range and measuring the received light intensity on the detection surface, the irradiation spot diameter of the first laser beam LB1, or the beam profile.

[0190] Next, it is determined whether the difference between the first focusing position and the first designated position is equal to or less than a first allowable value (step S2). Here, the first designated position is a position designated as the focusing position of the first laser light LB1. In this embodiment, the first designated position is zero in the Z direction with respect to the processing surface 90A. However, depending on the processing mode of the laser processing, the first designated position can take a negative value or a positive value. In this embodiment, when the first focusing position is above the processing surface 90A in the Z direction, the first focusing position is considered to be positive, and when it is below the processing surface 90A, the first focusing position is considered to be negative. Step S2 may be executed by the control unit 80 or may be executed by the processing operator.

[0191] If the determination result of step S2 is positive, that is, if the difference between the first focusing position and the first designated position is equal to or less than the first allowable value, the process proceeds to step S3. On the other hand, if the determination result of step S2 is negative, the optical component moving mechanism 57 is operated to adjust the position of the first lens, in this case the collimation lens 52, along the Z direction until the determination result of step S2 becomes positive (step S5).

[0192] In step S5, the difference between the position of the collimation lens 52 before executing step S5 and the position of the collimation lens 52 at the time when the determination result in step S2 becomes positive is stored in a storage unit provided in the control unit 80 as the amount of movement for correction. In addition, when the position of the collimation lens 52 before executing step S5 is set as a reference position and the collimation lens 52 is moved downward in the Z direction from the reference position after adjustment, the amount of movement is a negative value. When the collimation lens 52 is moved upward, the amount of movement is a positive value.

[0193] In step S3, the second laser oscillator 20 is operated to generate the second laser light LB2, and the second laser light LB2 is irradiated from the laser processing head 50 to the workpiece 90 while scanning the workpiece 90 within the irradiation range described above. Furthermore, the actual focusing position of the second laser light LB2 within the predetermined range (hereinafter referred to as the second focusing position) is confirmed.

[0194] Next, it is determined whether the difference between the second focusing position and the second designated position is equal to or less than a second tolerance (step S4). Here, the second designated position is a position designated as the focusing position of the second laser light LB2. In this embodiment, the second tolerance is the same as the first tolerance, and the first designated position and the second designated position are the same position along the Z direction. Similarly to the first designated position, the second designated position can be either a negative value or a positive value. Step S4 may be executed by the control unit 80 or by the processing operator.

[0195] If the determination result of step S4 is positive, that is, if the difference between the second focusing position and the second designated position is equal to or less than the second allowable value, the adjustment work is terminated. On the other hand, if the determination result of step S4 is negative, the lens barrel part 60 is operated to adjust the radial temperature gradient of the optical part held by the lens barrel part 60, in this case, the focus lens 53, until the determination result of step S4 becomes positive (step S6).

[0196] According to the method for adjusting the focusing positions of the first laser light LB1 and the second laser light LB2 according to the present embodiment, the collimation lens 52 (first lens) is moved along the Z direction based on the difference between the first focusing position and the first designated position. In this way, the shift of the focusing position due to the difference in the optical path length in the irradiation range can be corrected.

[0197] Furthermore, when assembling the laser processing head 50, a difference may occur between the focusing position of the first laser light LB1 and the focusing position of the second laser light LB2 due to assembly tolerances and size variations of the optical components arranged inside the housing 51. Furthermore, when installing the laser processing head 50 in the laser processing apparatus 200, the optical components arranged inside the housing 51 may become displaced from their predetermined positions.

[0198] On the other hand, according to the present embodiment, the refractive index of outer circumferential portion 53B relative to central portion 53A can be changed in focus lens 53 by adjusting the temperature gradient in the radial direction of focus lens 53. This changes the traveling direction of second laser light LB2 passing through outer circumferential portion 53B, and makes it possible to make the focusing position of first laser light LB1 and the focusing position of second laser light LB2 the same position along the Z direction.

[0199] (Other embodiments) The configuration of the optical coupler 30 is not particularly limited to that shown in Fig. 3. For example, as shown in Patent Document 3, an axicon lens may be used to make the first laser light LB1 incident on the first core 41 and the second laser light LB2 incident on the second core 43. Alternatively, a prism may be used to make the first laser light LB1 incident on the first core 41 and the second laser light LB2 incident on the second core 43. Alternatively, a diffraction grating may be used to make the first laser light LB1 incident on the first core 41 and the second laser light LB2 incident on the second core 43.

[0200] Moreover, it is preferable that the laser light sources constituting each of the first laser oscillator 10 and the second laser oscillator 20 are one or more semiconductor laser elements, in particular, laser diode bars each having a plurality of emitters that emit laser light. By configuring the laser light sources in this way, it is possible to miniaturize each of the first laser oscillator 10 and the second laser oscillator 20. Furthermore, since the semiconductor laser element has a high power-to-light conversion efficiency of about 40%, it is possible to generate high-power first laser light LB1 and second laser light LB2 with a small input power. [Industrial Applicability]

[0201] The laser processing head of the present disclosure has a simple configuration and is capable of focusing laser light of different wavelengths at the same focusing position, and is industrially useful. [Explanation of symbols]

[0202] 10 First laser oscillator 20 Second laser oscillator 30 Optical coupler 31 Case 31A 1st light entrance 31B 2nd light entrance 31C Light exit port 32 Reflective Mirror 33 Actuator 34 Dichroic Mirror 35 First focus lens 36 Quartz Block 40 Optical Fiber 40A input end 40B Output end 41 First Core 42 First Clad 43 Second Core 44 2nd Clad 50 Laser processing head 51 Case 51A Fiber connection port 51B Light exit port 52 Collimation Lens 52A Central part 52B Outer periphery 53 Second focus lens (focus lens) 53A Central part 53B Outer periphery 531 1st secondary lens 532 Secondary Lens 54 Reflective Mirror 55 1st Optical Scanner 55A 1st Galvano Motor 55B First Galvanometer Mirror (First Mirror) 56 Second Optical Scanner 56A 2nd Galvano Motor 56B Second Galvanometer Mirror (Second Mirror) 57 Optical component movement mechanism 57A 3rd Galvano Motor 57B First Base 57C Screw ring holder 57D 2nd Base 57E 1st Gear 57F 2nd Gear 57G Screw ring 57H O-ring 58 Beam Expander 59 Chromatic Aberration Correction Lens 60 Telescope barrel parts 60A heater (heating part) 60B Cooling section 70 Manipulator 71 Arm 72 Joint Axis 80 Control section 90 Work 90A machined surface 100 stages 200 Laser processing equipment LB1 First laser beam LB2 Second laser beam λ1: Wavelength of the first laser light (first wavelength) λ2: Wavelength of the second laser light (second wavelength)

Claims

1. A laser processing head including a housing and a plurality of optical components disposed inside the housing, the housing has a fiber connection port and a light exit port, An optical fiber is connected to the fiber connection port, The optical fiber has at least a first core provided at an axis and a second core provided radially outward of the first core and coaxially with the first core; A first laser light having a first wavelength is guided to the first core, A second laser light having a second wavelength shorter than the first wavelength is guided to the second core, At least one of the first laser light and the second laser light is emitted from the light emission port toward a workpiece, The optical components include at least a first lens, a second lens, a first mirror, and a second mirror; the first mirror and the second mirror are disposed at positions closer to the light exit port than the first lens and the second lens, the first mirror is configured to scan the first laser light or the second laser light, or both of the first laser light and the second laser light, in a Y direction that is one direction in a plane intersecting a Z direction that is a traveling direction of the first laser light and the second laser light, the second mirror is configured to scan the first laser light or the second laser light, or both of the incident first laser light and the second laser light, in an X direction intersecting the Y direction within the plane; the first laser light is transmitted through a central portion of each of the first lens and the second lens, the second laser light is transmitted through an outer periphery of each of the first lens and the second lens, The second lens has chromatic aberration corrected so that the first laser light and the second laser light are focused at the same position on the processing surface of the workpiece or in the vicinity of the processing surface, The laser processing head further comprises an optical component moving mechanism that moves the first lens along the Z direction.

2. 2. The laser processing head according to claim 1, the first lens is a collimation lens that collimates the first laser light, the second laser light, or both of the first and second laser lights guided into the housing by the optical fiber; A laser processing head characterized in that the second lens is a focus lens that focuses the first laser light and the second laser light, which have been collimated by the collimation lens, to the same focusing position on the processing surface of the workpiece or near the processing surface.

3. 2. The laser processing head according to claim 1, the second lens is a collimation lens that collimates the first laser light, the second laser light, or both of the first and second laser lights guided into the housing by the optical fiber; the first lens is a beam expander that expands the first laser light or the second laser light, or both of which have been transmitted through the collimation lens, in a direction perpendicular to the Z direction; the beam expander is disposed between the collimation lens and the focus lens; A laser processing head characterized in that the focus lens focuses the first laser light and the second laser light expanded by the beam expander to the same focusing position on the processing surface of the workpiece or near the processing surface.

4. 2. The laser processing head according to claim 1, the first lens is a collimation lens that collimates the first laser light, the second laser light, or both of the first and second laser lights guided into the housing by the optical fiber; the second lens is an aspheric lens disposed between the output end of the optical fiber and the collimation lens, A laser processing head, characterized in that the radius of curvature of the central portion of the second lens is different from the radius of curvature of the outer periphery.

5. 2. The laser processing head according to claim 1, the first lens is a beam expander that expands the first laser light or the second laser light, or both of the first and second laser lights incident thereon, in a direction perpendicular to the Z direction; the second lens is an aspheric lens disposed between the output end of the optical fiber and the beam expander, A laser processing head, characterized in that the radius of curvature of the central portion of the second lens is different from the radius of curvature of the outer periphery.

6. 2. The laser processing head according to claim 1, The first wavelength is equal to or greater than 800 nm and equal to or less than 1200 nm, A laser processing head, wherein the second wavelength is 380 nm or more and 660 nm or less.

7. 2. The laser processing head according to claim 1, The optical fiber connected to the laser processing head is the first core is configured so that a transmission loss of the second laser light is minimized or extremely small, the second core is configured so that a transmission loss of the first laser light is minimized or extremely small, A laser processing head characterized in that each optical characteristic is adjusted.

8. 2. The laser processing head according to claim 1, At least one of the plurality of optical components is held by a lens barrel component, the lens barrel component abuts against an outer periphery of the optical component to hold the optical component, The laser processing head is characterized in that the lens barrel component is configured to impart a temperature gradient to the optical component in a direction intersecting the Z direction.

9. 9. The laser processing head according to claim 8, A laser processing head, characterized in that the lens barrel component is configured to heat the optical component.

10. 9. The laser processing head according to claim 8, A laser processing head, wherein the lens barrel component is configured to cool the optical component.

11. A laser processing head according to any one of claims 1 to 10; a first laser oscillator that generates the first laser light; a second laser oscillator that generates the second laser light; an optical coupler that receives at least one of the first laser light and the second laser light and causes the first laser light to enter the first core and the second laser light to enter the second core; an optical fiber connected to the optical coupler and the laser processing head, and guiding at least one of the first laser light and the second laser light from the optical coupler to the laser processing head; A laser processing apparatus comprising at least a control unit that controls the operation of the laser processing head.

12. 12. The laser processing apparatus according to claim 11, When the first laser light and the second laser light are simultaneously irradiated onto the workpiece, A laser processing apparatus characterized in that the second laser light is irradiated coaxially with the first laser light on the processing surface of the workpiece, and the irradiation spot diameter of the second laser light is larger than the irradiation spot diameter of the first laser light.

13. 12. The laser processing apparatus according to claim 11, The control unit controls an operation of the optical coupler, the optical coupler includes at least a reflecting mirror, an actuator, and a dichroic mirror; the reflecting mirror reflects the incident second laser light toward an incident end of the optical fiber, the actuator is attached to the reflecting mirror, and adjusts an angle of the reflecting mirror based on a control signal from the control unit so that the second laser light is incident on the second core; the dichroic mirror is disposed on an optical path of the second laser light traveling from the reflecting mirror to the optical fiber and on an optical path of the first laser light, and is configured to transmit the second laser light incident thereon and to reflect the first laser light incident thereon; the first laser light reflected by the dichroic mirror is incident on the first core at the incident end, The laser processing apparatus, characterized in that the second laser light transmitted through the dichroic mirror is incident on the second core at the incident end.

14. A laser processing head according to any one of claims 8 to 10; a first laser oscillator that generates the first laser light; a second laser oscillator that generates the second laser light; an optical coupler that receives at least one of the first laser light and the second laser light and causes the first laser light to enter the first core and the second laser light to enter the second core; an optical fiber connected to the optical coupler and the laser processing head, and guiding at least one of the first laser light and the second laser light from the optical coupler to the laser processing head; A laser processing apparatus comprising at least a control unit that controls the operation of the laser processing head.

15. A method for adjusting focused positions of the first laser beam and the second laser beam in the laser processing apparatus according to claim 14, comprising the steps of: a first step of irradiating the first laser light onto the workpiece while scanning the first laser light within a predetermined irradiation range, and confirming a first focusing position that is an actual focusing position of the first laser light within the irradiation range; a second step of determining whether or not a difference between the first focusing position and a first designated position, which is a designated value of the focusing position of the first laser light, is equal to or smaller than a first allowable value; a third step of irradiating the second laser light onto the workpiece while scanning the second laser light within the irradiation range, and confirming a second focusing position that is an actual focusing position of the second laser light within the irradiation range; and a fourth step of determining whether or not a difference between the second focusing position and a second designated position, which is a designated value of the focusing position of the second laser light, is equal to or smaller than a second allowable value, When the determination result of the second step is negative, the optical component moving mechanism is operated to adjust the position of the first lens along the Z direction until the determination result becomes positive; If the determination result of the second step is positive, the third step is executed; If the result of the determination in the fourth step is negative, the lens barrel component is operated to adjust the temperature gradient of the optical component until the result of the determination in the fourth step is positive; The method for adjusting a focusing position, comprising the steps of: terminating the adjustment operation when the determination result in the fourth step is affirmative.

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