阅读说明：本技术 激光振荡器、使用了其的激光加工装置及激光振荡方法 (Laser oscillator, laser processing apparatus using the same, and laser oscillation method ) 是由 堂本真也 石川谅 加藤直也 于 2019-02-22 设计创作，主要内容包括：激光振荡器具备：多个激光模块；光束耦合器(12),其对从多个激光模块射出的多个激光束(LB1～LB4)进行耦合并作为耦合激光束而射出；以及聚光透镜单元,其具有聚光透镜,以使耦合激光束成为规定的光束直径的方式进行聚光并引导到传输光纤。光束耦合器(12)具有构成为能够变更激光束(LB1～LB4)的光路的光学构件(OC1～OC4)。通过由光学构件(OC1～OC4)变更激光束(LB1～LB4)的光路,不用调整聚光透镜的位置而使从传输光纤射出的耦合激光束的光束轮廓变化。(A laser oscillator is provided with: a plurality of laser modules; a beam coupler (12) that couples the plurality of laser beams (LB 1-LB 4) emitted from the plurality of laser modules and emits the coupled laser beams; and a condensing lens unit having a condensing lens for condensing the coupling laser beam so that the coupling laser beam has a predetermined beam diameter and guiding the coupling laser beam to the transmission fiber. The beam coupler (12) has optical members (OC 1-OC 4) configured to be able to change the optical paths of the laser beams (LB 1-LB 4). By changing the optical paths of the laser beams (LB 1-LB 4) by the optical members (OC 1-OC 4), the beam profile of the coupled laser beam emitted from the transmission fiber is changed without adjusting the position of the condenser lens.)

1. A laser oscillator is provided with:

a plurality of laser modules that emit laser beams, respectively;

a beam coupler that couples the plurality of laser beams emitted from the plurality of laser modules and emits the coupled laser beams; and

a condensing unit having a condensing lens for condensing the coupled laser beam so as to have a predetermined beam diameter and guiding the coupled laser beam to a transmission fiber,

the beam coupler includes an optical path changing mechanism configured to be capable of changing an optical path of at least one of the plurality of laser beams received from the plurality of laser modules,

by changing the optical path of the laser beam by the optical path changing mechanism, the beam profile of the coupled laser beam emitted from the transmission fiber is changed without adjusting the position of the condenser lens.

2. The laser oscillator of claim 1,

the transmission fiber has at least: a first core functioning as an optical waveguide; a second core that is in contact with an outer peripheral surface of the first core, is provided coaxially with the first core, and functions as an optical waveguide; and a clad layer which is in contact with an outer peripheral surface of the second core and is provided coaxially with the first core and the second core,

the condensing unit that guides the coupling laser beam to the first core when the optical path of the laser beam is not changed by the optical path changing mechanism; when the optical path of the laser beam is changed by the optical path changing mechanism, the coupling laser beam is guided to the first core body and the second core body, or the coupling laser beam is guided to the second core body.

3. The laser oscillator of claim 1,

the transmission fiber has at least: a first core functioning as an optical waveguide; a second core that is in contact with an outer peripheral surface of the first core, is provided coaxially with the first core, and functions as an optical waveguide; and a clad layer which is in contact with an outer peripheral surface of the second core and is provided coaxially with the first core and the second core,

the light condensing unit guides the coupling laser beam to the first core and the second core or guides the coupling laser beam to the second core when the optical path of the laser beam is not changed by the optical path changing mechanism; the coupling laser beam is guided to the first core while the optical path of the laser beam is changed by the optical path changing mechanism.

4. The laser oscillator according to any one of claims 1 to 3,

at least two of the plurality of laser beams are optically axially adjusted in the beam coupler so that the optical axes thereof are close to each other and parallel to each other before entering the condensing unit, and the optical path changing mechanism is provided for one of the plurality of laser beams on which the optical axis is adjusted.

5. The laser oscillator according to any one of claims 1 to 4,

the optical path changing mechanism is configured to shift the optical path of the laser beam in parallel by a predetermined distance.

6. The laser oscillator of claim 5,

the optical path changing mechanism is a parallel flat plate-like member transparent to the laser beam.

7. The laser oscillator according to any one of claims 1 to 6,

the optical path changing mechanism is provided to be movable between a first position on the optical path of the laser beam and a second position outside the optical path.

8. The laser oscillator of claim 7,

the optical path changing mechanism is provided so as to form a predetermined angle with respect to the optical path of a predetermined laser beam.

9. The laser oscillator of claim 6,

the optical path changing mechanism is provided on the optical path of the laser beam so as to form a first angle with respect to the optical path of the laser beam, and changes the optical path of the laser beam by rotating around the optical path at a second angle.

10. The laser oscillator according to any one of claims 1 to 9,

the laser oscillation outputs of the respective plurality of laser modules are individually controlled.

11. A laser processing device at least comprises:

a laser oscillator as claimed in any one of claims 1 to 10;

a laser beam emitting head mounted on an emitting end of the transmission optical fiber; and

and a control unit for controlling the operation of the optical path changing mechanism.

12. A laser oscillation method in a laser oscillator which is connected to a transmission fiber and includes a plurality of laser modules and a condenser lens,

the laser oscillation method includes the steps of:

a beam coupling step of coupling a plurality of laser beams emitted from the plurality of laser modules and emitting the coupled laser beams;

a condensing step of condensing the coupled laser beam so that the coupled laser beam has a predetermined beam diameter by the condensing lens and guiding the coupled laser beam to the transmission fiber; and

a beam profile changing step of changing a beam profile of the coupled laser beam emitted from the transmission fiber without adjusting a position of the condenser lens by changing an optical path of at least one of the laser beams among the plurality of laser beams received from the plurality of laser modules in the beam coupling step.

Technical Field

The present disclosure relates to a laser oscillator, a laser processing apparatus using the same, and a laser oscillation method.

Background

In recent years, with the increase in output of Direct Diode lasers (hereinafter, referred to as DDLs), the development of Laser processing apparatuses using DDLs has been accelerated. The DDL can obtain a high output exceeding several kW by coupling laser beams emitted from a plurality of laser modules. The coupled laser beam emitted from the beam coupler is guided to a processing head provided at an arbitrary point via a transmission fiber. At this time, the coupling laser beam emitted from the beam coupler is condensed by the condenser lens to a spot diameter that falls on the core of the transmission fiber, and then enters the transmission fiber.

However, a workpiece as a processing object in a laser processing apparatus is widely used from a thin plate to a thick plate. However, in order to achieve good processing, not only the beam output and various construction conditions, but also the beam profile becomes an important element. For example, when a thin plate is cut at high speed, it is required to condense a coupling laser beam having high output to a smaller spot diameter. In this case, the coupled laser beam emitted from the transmission fiber is adapted to the gaussian-shaped beam profile. Further, depending on the processing conditions, the core diameter of the transmission fiber is preferably small. On the other hand, when cutting a thick plate, in order to secure a wider cutting width than when cutting a thin plate, a spot diameter of a certain degree of size needs to be condensed. In addition, in order to obtain a good cross section, there is a beam profile more suitable than a simple gaussian beam.

In contrast, patent document 1 discloses the following structure: by providing a condensing lens near the entrance portion of the transmission fiber and changing the spot diameter of the coupling laser beam entering the transmission fiber on the entrance portion side, the beam profile of the coupling laser beam emitted from the transmission fiber can be adjusted.

Prior art documents

Patent document

Patent document 1: japanese laid-open patent publication No. 2015-500571

Disclosure of Invention

Problems to be solved by the invention

However, in the conventional configuration disclosed in patent document 1, the beam profile is changed by adjusting the position of the condenser lens. Therefore, fine adjustment of the position of the condenser lens is required, and a position control device for the condenser lens capable of performing the fine adjustment is required. In such a configuration, in order to perform precise position control of the condenser lens, the position control device becomes complicated and may become expensive.

The present disclosure has been made in view of the above circumstances, and an object thereof is to provide a laser oscillator capable of changing a beam profile of a coupling laser beam emitted from a transmission fiber with a relatively simple configuration, a laser processing apparatus using the laser oscillator, and a laser oscillation method.

Means for solving the problems

In order to achieve the above object, a laser oscillator of the present disclosure includes: a plurality of laser modules that emit laser beams, respectively; a beam coupler that couples a plurality of laser beams emitted from the plurality of laser modules and emits the coupled laser beams; and a condensing unit having a condensing lens for condensing the coupling laser beam so that the coupling laser beam has a predetermined beam diameter and guiding the coupling laser beam to the transmission fiber, wherein the beam coupler has an optical path changing mechanism configured to change an optical path of at least one of the plurality of laser beams received from the plurality of laser modules, and the optical path of the coupling laser beam emitted from the transmission fiber is changed by the optical path changing mechanism, thereby changing a beam profile of the coupling laser beam without adjusting a position of the condensing lens.

According to this configuration, the beam profile of the coupling laser beam emitted from the transmission fiber can be changed relatively easily.

Further, the laser processing apparatus of the present disclosure is characterized by including at least: the above laser oscillator; a laser beam emitting head mounted on an emitting end of the transmission optical fiber; and a control unit for controlling the operation of the optical path changing mechanism.

With this configuration, a beam profile according to the processing content, the shape of the object to be processed, and the like can be obtained, and laser processing of a desired quality can be performed.

Further, a laser oscillation method according to the present disclosure is a laser oscillation method in a laser oscillator connected to a transmission fiber and including a plurality of laser modules and a condenser lens, the laser oscillation method including the steps of: a beam coupling step of coupling a plurality of laser beams emitted from the plurality of laser modules and emitting the coupled laser beams; a condensing step of condensing the coupled laser beam so that the coupled laser beam has a predetermined beam diameter by a condensing lens and guiding the coupled laser beam to a transmission fiber; and a beam profile changing step of changing a beam profile of the coupled laser beam emitted from the transmission fiber without adjusting a position of the condensing lens by changing an optical path of at least one of the plurality of laser beams received from the plurality of laser modules in the beam coupling step.

According to this method, the beam profile of the coupling laser beam emitted from the transmission fiber can be changed relatively easily.

Effects of the invention

According to the present disclosure, the beam profile of the coupling laser beam emitted from the transmission fiber can be changed relatively easily.

Drawings

Fig. 1 is a schematic diagram illustrating a structure of a laser processing apparatus according to embodiment 1 of the present disclosure.

Fig. 2 is a partial schematic view showing the internal structure of the beam coupler.

Fig. 3A is a schematic diagram showing a beam profile in the case where the optical path is changed so that the coupled laser beam is incident on the first core.

Fig. 3B is a schematic diagram showing a beam profile in the case where the optical path is changed so that the coupling laser beam is incident on the first core and the second core.

FIG. 3C is a schematic view showing a beam profile in the case where the optical path is changed so that the coupled laser beam is incident on the second core

Fig. 4 is a schematic diagram showing an internal structure of the beam coupler at the time of laser oscillation.

Fig. 5 is a schematic diagram showing a beam profile of a laser beam when an optical path is changed.

Fig. 6 is a schematic diagram illustrating an optical path changing operation of the optical member according to the modification.

Fig. 7 is a schematic diagram showing an internal structure of the beam coupler of embodiment 2 of the present disclosure.

Fig. 8 is a schematic diagram showing a beam profile of a laser beam when the optical path is changed.

Detailed Description

Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. The following description of the preferred embodiment is merely exemplary in nature and is in no way intended to limit the disclosure, its application, or uses.

(embodiment mode 1)

[ Structure of laser processing apparatus ]

Fig. 1 is a schematic diagram of the structure of a laser processing apparatus 100 according to the present embodiment. In addition, fig. 2 is a partial schematic view of the internal structure of the beam coupler 12. Fig. 2 shows only a portion where the laser beam LB1 of the plurality of laser beams LB1 to LB4 described later travels. In the following description, the traveling direction of the laser beam LB1 incident on the beam coupler 12 from the plurality of laser modules 11 in fig. 2 is sometimes referred to as the X direction, the direction in which the laser beam LB1 reflected by the mirror M1 is directed toward the mirror M2 is sometimes referred to as the Z direction, and the direction perpendicular to the X direction and the Z direction is sometimes referred to as the Y direction.

The laser processing apparatus 100 includes a laser oscillator 10, a laser beam emitting head 30, a transmission fiber 40, a control unit 50, and a power supply 60. The laser oscillator 10 and the ends (hereinafter, simply referred to as incident ends) of the transmission fiber 40, at which the laser beams LB1 to LB4 are incident, are housed in a housing 70.

The laser oscillator 10 has a plurality of laser modules 11, a beam coupler 12, and a condenser lens unit (condenser unit) 20. The plurality of laser modules 11 include a plurality of laser diodes or laser arrays that emit laser beams LB1 to LB4 having different wavelengths, respectively. The laser beams LB1 to LB4 having different wavelengths emitted from the plurality of laser modules 11 are coupled into one laser beam (hereinafter referred to as a coupled laser beam) by the beam coupler 12. The coupled laser beam is condensed by a condenser lens 21 disposed in the condenser lens unit 20, and the beam diameter is reduced by a predetermined magnification and then enters the transmission fiber 40. By configuring the laser oscillator 10 in this manner, a high-output laser processing apparatus 100 having a laser beam output exceeding several kW can be obtained. The laser oscillator 10 is supplied with electric power from a power supply 60 described later to perform laser oscillation, and the coupling laser beam incident on the transmission fiber 40 is emitted from an end portion (hereinafter, simply referred to as an emission end) of the transmission fiber 40 from which the coupling laser beam is emitted.

The beam coupler 12 includes a plurality of mirrors M1 to M5 (see fig. 2 and 4) and a plurality of optical members (optical path changing mechanisms) OC1 to OC4 (see fig. 2 and 4) therein. The mirrors M1 to M5 are arranged obliquely with respect to the optical paths of the laser beams LB1 to LB4 so as to guide the laser beams LB1 to LB4 emitted from the laser modules 11 to the laser beam emitting unit LO (see fig. 2 and 4). The optical members OC1 to OC4 are parallel flat plate-like members made of quartz glass, and are transparent to any one of the laser beams LB1 to LB 4. The optical members OC1 to OC4 are provided so as to be movable between a predetermined position (first position) on the optical path of the predetermined laser beams LB1 to LB4 and a predetermined position (second position) outside the optical path. As shown in fig. 2, when the optical member OC1 is at the first position (the position of the optical member OC1 shown by the broken line) and at the second position (the position of the optical member OC1 shown by the solid line), the optical path of the laser beam LB1 is changed to the optical path of the arrow shown by the broken line and the optical path of the arrow shown by the solid line in a switched manner. This is described in detail later. The actuators for moving the optical members OC1 to OC4 are not shown and described.

The condenser lens unit 20 has a condenser lens 21 therein, and the condenser lens 21 condenses the coupling laser beam so that a spot diameter at an incident end of the transmission fiber 40 is smaller than a sum of core diameters of a first core 41 and a second core 42, which will be described later. The condenser lens unit 20 has a connector, not shown, to which the incident end of the transmission fiber 40 is connected.

The transmission fiber 40 is optically coupled to the condenser lens 21 of the laser oscillator 10, and transmits the coupled laser beam received from the laser oscillator 10 via the condenser lens 21 to the laser beam emitting head 30. The transmission fiber 40 has a first core 41 having a substantially circular cross section at the axial center. The transmission fiber 40 has a second core 42, and the second core 42 is in contact with the outer peripheral surface of the first core 41 and is provided coaxially with the first core 41. When the coupling laser beam is incident on at least one of the first core 41 and the second core 42, the coupling laser beam is transmitted to the exit end of the transmission fiber 40.

In the transmission fiber 40, a clad 43 is provided in contact with the outer peripheral surface of the second core 42 and coaxially with the first core 41 and the second core 42, and the refractive index of the clad 43 is lower than the refractive indices of the first core 41 and the second core 42. The first core 41 has a refractive index higher than that of the second core 42. In the present embodiment, the material of the first core 41 is quartz glass (refractive index: about 1.45), and the material of the second core 42 is fluorine-doped quartz glass (refractive index: about 1.445). The clad 43 is made of silica glass (refractive index: about 1.43) doped with fluorine at a higher concentration than the second core 42. Note that both the first core 41 and the second core 42 may be made of quartz glass, and a low refractive index layer of quartz glass having a lower refractive index than the first core 41 and the second core 42 and doped with fluorine may be interposed between the first core 41 and the second core 42.

In the above, the transmission fiber 40 has the second core 42 that is in contact with the outer peripheral surface of the first core 41 and is provided coaxially with the first core 41, and the clad 43 is provided in contact with the outer peripheral surface of the second core 42 and is provided coaxially with the first core 41 and the second core 42, but the second core 42 may be a clad. In other words, the first clad layer may be provided coaxially with the first core 41 in contact with the outer peripheral surface of the first core 41, and the second clad layer (clad layer 43) may be provided coaxially with the first core 41 and the first clad layer in contact with the outer peripheral surface of the first clad layer (second core 42).

With the transmission fiber 40 configured as described above, the coupling laser beam incident from the condenser lens unit 20 is totally reflected in the first core 41 and the second core 42 or in the second core 42, and then emitted from the emission end of the transmission fiber 40. That is, at least one of the first core 41 and the second core 42 functions as an optical waveguide for coupling the laser beam, and the clad 43 functions as a light-sealing portion for sealing the coupling laser beam into the first core 41 and the second core 42, which are optical waveguides. The surface of the clad 43 is covered with a film, which is not shown.

The laser beam emitting head 30 irradiates the coupled laser beam transmitted in the transmission fiber 40 toward the outside. For example, in the laser processing apparatus 100 shown in fig. 1, a coupled laser beam is emitted toward a workpiece (not shown) that is an object to be processed and is disposed at a predetermined position.

The control unit 50 controls laser oscillation of the laser oscillator 10. Specifically, the laser oscillation control of each laser module 11 is performed by supplying control signals such as an output voltage and an on time to the power supply 60 connected to the laser oscillator 10. It is also possible to individually perform laser oscillation control for each laser module 11. For example, the laser oscillation output, the on time, and the like may be different for each laser module 11. The controller 50 controls the operations of the optical members OC1 to OC4 disposed in the beam coupler 12, specifically, the operations of actuators (not shown) connected to the optical members OC1 to OC 4. The control unit 50 may control the operation of a manipulator (not shown) to which the laser beam emitting head 30 is attached.

As described above, the power supply 60 supplies power for performing laser oscillation to the laser oscillator 10, specifically, each of the plurality of laser modules 11. The power supplied to each laser module 11 may be different according to an instruction from the control unit 50. The power supply 60 may supply power to each movable portion of the laser processing apparatus 100, or may supply power from another power supply (not shown) to the movable portion of the laser processing apparatus 100.

[ Beam Profile of coupled laser Beam ]

When laser processing is performed using the laser processing apparatus 100 shown in fig. 1, the beam profile of the coupled laser beam may be changed depending on the object to be processed and the processing content. In such a case, the beam profile of the coupled laser beam emitted from the transmission fiber 40 can be changed by changing the incident position of the coupled laser beam at the incident end of the transmission fiber 40. For ease of description, first, how the beam profile changes will be described below with reference to fig. 3A to 3C in the case of using a conventional method in which the optical path of the coupling laser beam is changed by adjusting the position of the condensing lens 21.

Fig. 3A to 3C are schematic diagrams showing a relationship between the optical path (incident position) of the coupling laser beam and the beam profile of the coupling laser beam emitted from the transmission fiber 40. The transmission fiber 40 will be described by taking an example of a structure shown in fig. 1 and 2, that is, an optical fiber having a double core structure including a first core 41 and a second core 42.

As shown in the lower left of fig. 3A, the laser beam is incident-coupled to the transmission fiber 40 after the position of the condensing lens 21 is adjusted so as to fall within the core diameter of the first core 41. In this way, the beam profile of the coupling laser beam emitted from the transmission fiber 40 has a single-peak gaussian distribution (see the lower right of fig. 3A). In the present specification, the term "beam profile" refers to the spatial distribution of the intensity of a laser beam. In fig. 3A to 3C, the laser beam intensity is represented by a waveform change in the Z direction, and the spatial distribution is represented by a waveform change in the X direction. In the present embodiment, the Y-direction waveform change is also the same as the X-direction waveform change, and is not shown. However, the spatial distribution may also be different in the X and Y directions.

On the other hand, as shown in fig. 3B, when the condensing lens 21 is moved by a predetermined amount in the direction intersecting the optical path of the coupling laser beam, in this case, in the Z direction, the coupling laser beam enters not only the first core 41 but also the second core 42 (see the lower left of fig. 3B). In this way, the beam profile of the coupling laser beam emitted from the transmission fiber 40 has a shape having three peaks, and the half-value width of the beam profile is larger than that in the case shown in fig. 3A (see the lower right of fig. 3B).

When the condenser lens 21 is further moved in the Z direction from the state of fig. 3B, the coupling laser beam enters only the second core 42 (see the lower left of fig. 3C). Thus, the beam profile of the coupled laser beam emitted from the transmission fiber 40 becomes a shape having two peaks. In addition, the half-value width of the beam profile is larger than that in the case shown in fig. 3A (see the lower right of fig. 3C), but the half-value width of the beam profile is smaller than that in the case shown in fig. 3B.

In this way, by adjusting the position of the condensing lens 21 for guiding the coupling laser beam to the transmission fiber 40, the laser beam incident position at the incident end of the transmission fiber 40 can be varied, thereby adjusting the ratio of the coupling laser beam propagating in the first core 41 to the coupling laser beam propagating in the second core 42. Further, as shown in fig. 3A to 3C, by continuously changing the position of the condensing lens 21, the beam profile of the coupling laser beam can be adjusted without a step, and a desired beam profile can be obtained.

[ Beam Profile Change action of coupled laser Beam ]

However, the core diameter of the first core 41 of the transmission fiber 40 is generally small on the order of several tens μm to several hundreds μm, and in order to change the beam profile of the coupling laser beam as shown in fig. 3A to 3C, it is necessary to precisely adjust the position of the condenser lens 21 that causes the coupling laser beam to enter the transmission fiber 40, which complicates the position control. In addition, the position control device for position adjustment also becomes expensive.

In this regard, in the present disclosure, the following structure is proposed: the optical path of at least one of the laser beams LB1 to LB4 emitted from the laser modules 11 is changed by an optical member, thereby changing the beam profile of the coupled laser beam emitted from the transmission fiber 40.

Fig. 4 is a schematic diagram of the internal structure of the beam coupler 12 at the time of laser oscillation according to the present embodiment. Fig. 5 is a schematic view of the beam profile of the coupled laser beam when the optical path is changed. In the present embodiment, an example is shown in which the laser beams LB1 to LB4 emitted from the four laser modules 11 are coupled into one coupled laser beam in the beam coupler 12 and emitted toward the condenser lens unit 20. However, the number of laser modules 11 and the number of laser beams to be emitted are not particularly limited. The beam profile shown in fig. 5 describes changes in a plane defined by the X direction and the Z direction, similarly to the beam profiles shown in fig. 3A to 3C.

As shown in fig. 4, the beam coupler 12 is provided with laser beam incident portions LI1 to LI4 corresponding to the four laser beams LB1 to LB4, and a laser beam emitting portion LO for emitting the coupled laser beams. In the beam coupler 12, the five mirrors M1 to M5 are arranged so as to form predetermined angles with respect to the optical paths of the laser beams LB1 to LB4 in the vicinity of the laser beam incident sections LI1 to LI4, respectively. Optical members OC1 to OC4 are disposed between the laser beam incident portions LI1 to LI4 and the mirrors M1 to M4, respectively. The optical members OC1 to OC4 are arranged such that the surfaces thereof form predetermined angles larger than 0 ° and smaller than 90 ° with respect to the optical paths of the corresponding laser beams LB1 to LB4 in the vicinity of the laser beam incident portions LI1 to LI4, respectively. In addition, as described above, the optical members OC1 to OC4 are respectively provided to be movable between a first position on the optical path of the corresponding laser beams LB1 to LB4 and a second position outside the optical path.

First, consider a case where all of the optical members OC1 to OC4 are outside the optical path of the corresponding laser beams LB1 to LB4, i.e., at the second position. When the four laser beams LB1 to LB4 enter the beam coupler 12, the laser beam LB1 entering from the laser beam entrance unit LI1 is reflected by the mirror M1 and travels toward the mirror M2. The laser beam LB1 is further reflected by the mirror M2 and travels toward the laser beam emitting portion LO. Similarly, the laser beam LB3 is reflected by the mirror M3 and the mirror M5, respectively, and travels toward the laser beam emitting portion LO, and the laser beam LB4 is reflected by the mirror M4 and the mirror M5, respectively, and travels toward the laser beam emitting portion LO. On the other hand, the laser beam LB2 incident from the laser beam incident portion LI2 travels straight and directly toward the laser beam emitting portion LO. As a result, the laser beams LB1 to LB4 are in a state of approaching the optical axis near the laser beam emitting portion LO, and are emitted from the laser beam emitting portion LO as one coupled laser beam. Therefore, as shown in mode a of fig. 5, the beam profile of the coupled laser beam becomes a gaussian distribution in a single peak. Since the optical axes of the laser beams LB1 to LB4 do not coincide completely, the coupled laser beams have beam profiles that are spatially expanded from the laser beams LB1 to LB4, respectively.

Next, a case is considered in which only the optical member OC1 is moved to the optical path of the laser beam LB1, i.e., the first position, from a state in which all the optical members OC1 to OC4 are outside the optical paths of the corresponding laser beams LB1 to LB4, i.e., the second position. In this case, since the refractive index of the optical member OC1 (about 1.45 as silica glass) is higher than the refractive index of the space through which the laser beam LB1 passes (about 1 as in air), the laser beam LB1 is refracted when entering the optical member OC1, and the optical path in the optical member OC1 is changed. Likewise, when the laser beam LB1 is refracted when exiting from the optical member OC1, the optical path of the laser beam LB1 is altered. That is, when the optical member OC1 is on the optical path of the laser beam LB1 or outside the optical path, the optical path of the laser beam LB1 is changed, and in the coupled laser beam, the laser beam LB1 is in a state in which the optical axis is shifted from the other three laser beams LB2 to LB 4. In addition, the refractive index and thickness of the optical member OC1 are set such that the laser beam LB1 is incident on the second core 42 with the optical member OC1 inserted into the optical path of the laser beam LB 1. Therefore, as shown in pattern B of fig. 5, the laser beams LB2 to LB4 are incident on the first core 41, and the laser beam LB1 is incident on the second core 42. As a result, as shown in mode B of fig. 5, the beam profile of the coupling laser beam has peaks on both sides of the single-peak gaussian distribution and has a shape having three peaks. In addition, the height of each peak is lower than the height of the beam profile shown in mode a. The beam profile shown in pattern B of fig. 5 has a waveform shape that expands in the X direction compared to the beam profile shown in pattern a.

Note that, by disposing any one of the optical members OC1 to OC4 on the optical path of the corresponding laser beam, the beam profile shown in pattern B of fig. 5 can be obtained. The refractive index and thickness of the optical members OC2 to OC4 are set so that the corresponding laser beams enter the second core 42 when the optical members OC2 to OC4 are inserted into the optical paths of the corresponding laser beams, respectively.

Next, consider the following: from the state where all of the optical members OC1 to OC4 are outside the optical paths of the corresponding laser beams LB1 to LB4, that is, at the second position, two of the optical members OC1 to OC4 are arranged on the optical paths of the corresponding laser beams, and for example, the optical members OC1 and OC2 are arranged on the optical paths of the laser beams LB1 and LB2, respectively.

In this case, the optical paths of the laser beams LB1 and LB2 are changed by the optical members OC1 and OC2, respectively, and thereby the laser beams LB1 and LB2 are incident on the second core 42. As a result, as shown in mode C of fig. 5, the beam profile of the coupling laser beam has a shape having three peaks. The height of the central peak among the three peaks is lower than the height of the corresponding portion of the beam profile shown in the pattern B, but the heights of the peaks on both sides are higher than the height of the corresponding portion of the beam profile shown in the pattern B. This is because the incident amount of the coupling laser beam incident on the second core 42 increases as compared with the case shown in mode B.

In addition, consider the following: three of the optical members OC1 to OC4 are disposed on the optical path of the corresponding laser beams, for example, the optical members OC1 to OC3 are disposed on the optical paths of the laser beams LB1 to LB3, respectively, from the state where all of the optical members OC1 to OC4 are outside the optical paths of the corresponding laser beams LB1 to LB4, that is, at the second position. In this case, the optical paths of the laser beams LB1 to LB3 are changed by the optical members OC1 to OC3, respectively, whereby the laser beams LB1 to LB3 are incident on the second core 42. As a result, as shown in mode D of fig. 5, the beam profile of the coupling laser beam has a shape having three peaks. The height of the central peak among the three peaks is lower than the height of the corresponding portion of the beam profile shown in the pattern C, but the heights of the peaks on both sides are higher than the height of the corresponding portion of the beam profile shown in the pattern C. This is because the incident amount of the coupling laser beam incident on the second core 42 increases as compared with the case shown in mode C. In addition, in the case of mode C, the peak values at both sides of the beam profile of the coupling laser beam are higher than the peak value at the center.

As shown in fig. 4, when all of the optical members OC1 to OC4 are disposed on the optical path of the corresponding laser beams, that is, the first position from the state where all of the optical members OC1 to OC4 are outside the optical path of the corresponding laser beams LB1 to LB4, that is, the second position, the optical paths of the laser beams LB1 to LB4 are changed by the optical members OC1 to OC4, and thereby all of the laser beams LB1 to LB4 enter the second core 42. As a result, as shown in mode E of fig. 5, the beam profile of the coupling laser beam becomes a shape having two peaks. This is because there is no laser beam incident on the first core 41, and the heights of the two peaks are higher than those of the peaks on both sides in the beam profile shown in the mode D.

[ Effect and the like ]

As described above, the laser oscillator 10 of the present embodiment includes: four laser modules 11, which respectively emit laser beams LB 1-LB 4; a beam coupler 12 that couples the four laser beams LB1 to LB4 emitted from the four laser modules 11 and emits the coupled laser beams; and a condenser lens unit 20 having a condenser lens 21 for condensing the coupled laser beam so as to have a predetermined beam diameter and guiding the condensed coupled laser beam to the transmission fiber 40. The beam coupler 12 includes optical members OC1 to OC4, and the optical members OC1 to OC4 are configured to be able to change the optical path of at least one of the four laser beams LB1 to LB4 received from the four laser modules 11. By changing the optical path of at least one of the optical paths of the laser beams LB1 to LB4 by the optical members OC1 to OC4, the beam profile of the coupled laser beam emitted from the transmission fiber 40 is changed without adjusting the position of the condenser lens 21.

By configuring the laser oscillator 10 in this manner, the beam profile of the coupling laser beam emitted from the transmission fiber 40 can be easily changed, and a beam profile according to the laser processing content, the shape of the object to be processed, and the like can be obtained. This enables laser processing of desired quality.

For example, when the thin steel sheet is cut by the laser processing apparatus 100, it is preferable to increase the energy density of the cut portion, and the cutting width is preferably as narrow as possible. Thus, as shown in mode a of fig. 5, the beam profile is preferably controlled to have a gaussian distribution with a single peak. On the other hand, when the thick steel plate is cut by the laser processing apparatus 100, the cutting width also needs to be widened to some extent according to the thickness of the steel plate. Therefore, as shown in modes B to E of fig. 5, it is preferable that at least one of the optical paths of the laser beams LB1 to LB4 is changed by the optical members OC1 to OC4 to be incident on the second core 42, thereby controlling the beam profile to a spatially widened shape. In addition, in the cutting process by the laser beam, the sputtered material may be scattered from the workpiece as the object to be processed, and may be re-attached to the workpiece to deteriorate the processing quality. By selecting any one of the beam profiles shown in the modes B to E, the generation of such a sputtered substance can be suppressed. In general, as the peak height of the beam profile indicating the intensity of the laser beam is lower, generation of the sputtered substance is more easily suppressed.

In addition, the transmission fiber 40 has at least: a first core 41 functioning as an optical waveguide; a second core 42 that is in contact with the outer peripheral surface of the first core 41, is provided coaxially with the first core 41, and functions as an optical waveguide; and a clad 43 which is in contact with the outer peripheral surface of the second core 42 and is provided coaxially with the first core 41 and the second core 42. The condenser lens unit 20 guides the laser beams LB1 to LB4 to the first core 41 of the delivery fiber 40 when the optical paths of the laser beams LB1 to LB4 are not changed by the optical members OC1 to OC4, and guides the laser beams whose optical paths are changed to the second core 42 when the optical paths of the laser beams LB1 to LB4 are changed by the optical members OC1 to OC 4. That is, by using the optical members OC1 to OC4, the coupling laser beam may be guided only to the first core 41, may be guided to the first core 41 and the second core 42, or may be guided only to the second core 42. Therefore, the beam profile of the coupling laser beam emitted from the transmission fiber 40 can be easily changed.

The optical members OC1 to OC4 are configured to shift the optical paths of the laser beams LB1 to LB4 in parallel by a predetermined distance. By configuring the optical members OC1 to OC4 in this manner, the optical path of the laser beam after the optical path change is accurately defined, and therefore, the ratio of the laser beam incident on the first core 41 and the second core 42 of the transmission fiber 40 can be accurately and reproducibly adjusted. Further, by making the optical members OC1 to OC4 parallel flat plate-shaped members transparent to the laser beams LB1 to LB4, the optical paths of the laser beams LB1 to LB4 can be shifted in parallel by a predetermined distance.

In addition, the optical members OC1 to OC4 are disposed so as to form a predetermined angle with respect to the optical paths of the laser beams LB1 to LB4, and are disposed so as to be movable between a first position on the optical paths of the laser beams LB1 to LB4 and a second position outside the optical paths. By configuring the optical members OC1 to OC4 in this manner, a sufficient margin can be secured for the adjustment of the optical coupling between the transmission fiber 40 and the coupled laser beam after the optical path is changed. Further, the beam profiles of the coupled laser beams emitted from the transmission fiber 40 can be changed with a simple configuration without changing the optical paths of the laser beams LB1 to LB4 by finely adjusting the position of the condenser lens 21 and the angles of the mirrors M1 to M5 in the beam coupler 12.

As described above, in the vicinity of the laser beam emitting section LO of the beam coupler 12, the optical axes of the plurality of laser beams LB1 to LB4 do not completely coincide with each other, and therefore the coupled laser beams have a spatially expanded beam profile. That is, the coupling laser beam has a beam diameter larger than the beam diameters of the laser beams LB1 to LB 4. For example, as shown in the present embodiment, when the coupling laser beam is generated by using four laser modules 11 having an output of 1kW, the beam diameter thereof is limited to about 80 μm. Therefore, when the coupled laser beam is made to enter the first core 41 of the transmission fiber 40 with a predetermined margin, the minimum core diameter of the first core 41 needs to be about 100 μm. On the other hand, the core diameter of the second core 42 can be generally larger than that of the first core 41. This is because the core diameter of the first core 41 is required to be smaller in order to increase the optical density in the first core 41 as much as possible, whereas the core diameter larger than the first core 41 is often selected in the second core 42 in order to disperse the optical density. For example, when the core diameter of the second core 42 is 360 μm, the width of the second core 42 in the radial direction of the transmission fiber 40 is 130 μm. When the coupling laser beam is made to enter the second core 42, there is a margin for adjusting the optical coupling between the transmission fiber 40 and the coupling laser beam, as compared with the case where the coupling laser beam is made to enter the first core 41 entirely. The core diameter of the second core 42 is preferably 3 times or more the core diameter of the first core 41.

The arrangement of the optical system of the laser oscillator 10 may be initially adjusted to include the angle of the optical member with respect to the corresponding laser beam. That is, for example, when all of the optical members OC1 to OC4 are out of the optical path and all of the coupling laser beams are incident on the first core 41, the optical paths of the laser beams LB1 to LB4 can be changed by a simple operation of inserting or retracting the optical members OC1 to OC4 into or from the optical paths of the laser beams LB1 to LB 4. Further, the arrangement of the optical members OC1 to OC4 before and after the movement is not required to be highly accurate. For example, when the optical members OC1 to OC4 are moved to the first position on the optical path of the laser beams LB1 to LB4, the position is shifted by 10% or more from the target value. In this case, the optical members OC1 to OC4 form predetermined angles of more than 0 ° and less than 90 ° with respect to the optical paths of the laser beams LB1 to LB4, respectively, and therefore do not affect the optical paths of the laser beams LB1 to LB4 changed by the optical members OC1 to OC 4. This enables the beam profile of the coupling laser beam to be changed easily and with good reproducibility.

The laser processing apparatus 100 of the present embodiment includes at least the laser oscillator 10 described above, the laser beam emitting head 30 attached to the emission end of the transmission fiber 40, and the control unit 50 that controls the operations of the optical members OC1 to OC 4.

By configuring the laser processing apparatus 100 in this manner, the beam profile of the coupled laser beam emitted from the laser beam emitting head 30 can be changed easily and with good reproducibility, and a beam profile corresponding to the laser processing content, the shape of the object to be processed, and the like can be obtained. This enables laser processing of desired quality.

< modification example >

Fig. 6 is a schematic diagram showing an optical path changing operation of the optical member according to the present modification.

The configuration shown in this modification is different from the configuration shown in embodiment 1 in the displacement form of the optical member OC1 before and after the optical path change. In embodiment 1, the optical path of the laser beam LB1 is changed by the difference in refractive index between the atmosphere and the optical member OC1 by disposing the optical member OC1 at the first position on the optical path of the laser beam LB 1. On the other hand, in the present modification, the optical member OC1 is disposed in advance at the first position on the optical path of the laser beam LB1, and the laser beam LB1 is made incident on the first core 41. When the optical path is changed, the optical path of the laser beam LB1 is changed by rotating the optical member OC1 by a predetermined angle, in this case 90 °, around the optical axis of the laser beam LB 1. That is, the laser beam LB1 is made incident on the second core 42.

As shown in fig. 6, the direction in which the laser beam LB1 in the optical member OC1 is refracted is changed by changing the angle of the optical member OC1 with respect to the optical path of the laser beam LB1, and as a result, the optical path of the laser beam LB1 emitted from the optical member OC1 is changed.

According to this modification, as in embodiment 1, the beam profile of the coupling laser beam emitted from the transmission fiber 40 can be changed easily and with good reproducibility, and a beam profile according to the laser processing content, the shape of the object to be processed, and the like can be obtained. This enables laser processing of desired quality. Further, since the space for moving the optical member OC1 can be reduced, the beam coupler 12 can be downsized, and the space of the laser oscillator 10 can be saved. In the present modification, the rotation angle of the optical member OC1 is set to 90 °, but other angles may be used.

(embodiment mode 2)

Fig. 7 is a schematic diagram showing the internal structure of the beam coupler 12A according to the present embodiment, and fig. 8 is a schematic diagram showing the beam profile of the laser beam when the optical path is changed. In the present embodiment, the same portions as those in embodiment 1 are denoted by the same reference numerals, and detailed description thereof is omitted.

The configuration shown in this modification differs from the configuration shown in embodiment 1 in the number and the arrangement position of the optical members. As shown in embodiment 1, in the case where the optical members OC1 to OC4 are arranged for the laser beams LB1 to LB4 before coupling, respectively, the beam profiles of the actually generated coupled laser beams are 5. In contrast, the arrangement pattern of the optical members OC1 to OC4 with respect to the optical paths of the laser beams LB1 to LB4 is 16, and the movement control of the optical members OC1 to OC4 becomes redundant. Further, when the control unit 50 controls the operations of the optical members OC1 to OC4, complicated control is required.

In contrast, in the present embodiment, it is noted that before the plurality of laser beams LB1 to LB4 are finally coupled, the optical axes of the laser beams are close to each other and parallel to each other. That is, by disposing one optical member for the optical paths of the plurality of laser beams in such a state, the number of optical members to be disposed is reduced. This can simplify the operation control of the optical member.

For example, as shown in fig. 7, the optical axis of the laser beam LB1 reflected by the mirror M2 is close to the optical axis of the laser beam LB2, and both of the laser beams LB1 and LB2 are incident on the laser beam emitting section LO in parallel. The optical member OC5 is disposed in common with the optical path of the laser beam LB2 and the laser beam LB1 reflected by the mirror M2. Further, the optical axis of the laser beam LB3 traveling between the mirror M3 and the mirror M5 is close to the optical axis of the laser beam LB4 traveling between the mirror M4 and the mirror M5, and both the laser beams LB3 and LB4 enter the mirror M5 in parallel. The optical member OC6 is disposed in common for the optical paths of the laser beams LB3, LB4 between the mirrors M3, M4 and the mirror M5.

As described above, at least two of the plurality of laser beams LB1 to LB4 are optically axis-adjusted in the beam coupler 12A so that the optical axes are close to each other and parallel to each other before entering the condenser lens unit 20, and one optical member is provided for the optical path of the plurality of laser beams LB1 to LB4, the optical path of which is optically axis-adjusted. In this way, as shown in fig. 8, the arrangement pattern of each optical member can be reduced, and the beam profiles of 5 kinds of coupled laser beams can be generated as in the structure shown in embodiment 1. The arrangement pattern of the optical members is not limited to the above, and other patterns may be adopted. For example, a mode in which one optical member is disposed between the laser beam incident portion LI1 and the mirror M1 and between the mirror M5 and the laser beam emitting portion LO is considered, and this is not shown. In this case, although the beam profile of the coupling laser beam actually generated is reduced to 4 types, the arrangement pattern of the optical members with respect to the optical paths of the laser beams LB1 to LB4 can be reduced to 4 types, and the operation control of the optical members can be simplified.

(other embodiments)

The displacement form of the optical member OC1 shown in the modification can be applied to the optical members OC2 to OC4 shown in embodiment 1 and the optical members OC5 and OC6 shown in embodiment 2, and in this case, the same effect as that of embodiment 2 is also obtained. Further, not limited to this, the components described in the above embodiments may be combined to form a new embodiment.

The surfaces of the optical members OC1 to OC6 may be coated with an antireflection coating with respect to the laser beam. Unnecessary reflection in the optical members OC1 to OC6 is suppressed, and the utilization efficiency of the laser beam is improved. This can suppress an increase in power consumption of the laser oscillator 10. In embodiments 1 and 2 including the modified examples, the optical members OC1 to OC6 are parallel flat plate-shaped members, but other members such as prisms may be used.

Further, the initial position of the optical system of the laser oscillator 10 may be adjusted in a state where the optical members OC1 to OC6 are arranged on the optical paths of the laser beams LB1 to LB 4. In this case, the optical paths of the laser beams LB1 to LB4 are changed by retracting the optical members OC1 to OC6 to the outside of the optical paths of the laser beams LB1 to LB 4. Therefore, the condenser lens unit 20 guides the laser beams LB1 to LB4 to the second core 42 of the delivery fiber 40 when the optical paths of the laser beams LB1 to LB4 are not changed by the optical members OC1 to OC 6. When the optical paths of the laser beams LB1 to LB4 are changed by the optical members OC1 to OC6, any one of the laser beams LB1 to LB4 whose optical paths have been changed is guided to the first core 41. Even in such a configuration, the coupling laser beam can be guided only to the first core 41, the coupling laser beam can be guided to the first core 41 and the second core 42, or the coupling laser beam can be guided only to the second core 42. Therefore, the beam profile of the coupling laser beam emitted from the transmission fiber 40 can be easily changed. In embodiment 1, the core diameter of the second core 42 is 3 times or more the core diameter of the first core 41, but the configuration is not limited to this. The above-described configuration is to guide the laser beams LB1 to LB4 to the second core 42 of the delivery fiber 40 when the optical paths of the laser beams LB1 to LB4 are not changed by the optical members OC1 to OC 6. When the optical paths of the laser beams LB1 to LB4 are changed by the optical members OC1 to OC6, any one of the laser beams LB1 to LB4 whose optical paths have been changed is guided to the first core 41. In such a structure, the core diameter of the second core 42 may be smaller than 3 times the core diameter of the first core 41.

Further, the outputs of the laser beams LB1 to LB4 output from the plurality of laser modules 11 may be individually controlled. For example, the outputs of the laser beams LB1 to LB4 output from the plurality of laser modules 11 may be different from each other. When the maximum value of the laser oscillation output of the laser module 11 shown in the present embodiment is 1kW, the maximum output of the coupling laser beam is 4 kW. By individually controlling the laser oscillation output of each laser module 11, the maximum output of the coupling laser beam becomes 4kW or less, but the pattern of the obtained beam profile can be greatly increased. This enables a beam profile optimal for the desired laser processing to be selected finely, thereby improving the processing quality.

Industrial applicability

The laser oscillator and the laser oscillation method according to the present disclosure can easily and reproducibly change the beam profile of the coupled laser beam to be output, and are therefore useful for application to a laser processing apparatus used for welding, cutting, and the like.

Description of reference numerals:

10 laser oscillator;

11 a laser module;

12a beam coupler;

a 12A beam coupler;

20 a condenser lens unit (condensing unit);

21 a condenser lens;

30 a laser beam emitting head;

40 a transmission optical fiber;

41 a first core;

42 a second core;

43 a cladding layer;

50 a control unit;

60 power supply;

70 a housing;

100 laser processing device;

an LB1 laser beam;

an LB2 laser beam;

an LB3 laser beam;

an LB4 laser beam;

an LI1 laser beam incident part;

an LI2 laser beam incident part;

an LI3 laser beam incident part;

an LI4 laser beam incident part;

an LO laser beam emitting unit;

an M1 mirror;

an M2 mirror;

an M3 mirror;

an M4 mirror;

an M5 mirror;

an OC1 optical member (optical path changing mechanism);

an OC2 optical member (optical path changing mechanism);

an OC3 optical member (optical path changing mechanism);

an OC4 optical member (optical path changing mechanism);

an OC5 optical member (optical path changing mechanism);

an OC6 optical member (optical path changing mechanism).