Method for adjusting focal position of laser light

Abstract

The method for adjusting the focal position of the laser beam includes a first step of inserting a first holder holding a protective glass and an aperture for limiting a beam diameter of the guide laser beam into an insertion hole provided at the bottom of the laser head, a second step of irradiating the guide laser beam, and a third step of determining whether or not the focal position of the laser beam is within a predetermined range including the reference position based on a comparison between a test piece provided at a reference position corresponding to the focal position of the guide laser beam and the beam diameter of the guide laser beam displayed on the test piece during the execution of the second step.

Description

[Technical field]

[0001] The present disclosure relates to a method for adjusting the focal position of laser light. [Background technology]

[0002] Patent Document 1 discloses a method for adjusting the focal position of laser light, which is executed by a laser processing device including at least a laser oscillator that generates a laser beam, a laser head that irradiates the laser beam toward a workpiece, and an articulated robot to which the laser head is attached. This method includes a first step of attaching a gauge, which is a member for confirming the focal position, to a connecting part that is attached to a hand shaft that is rotatable about a predetermined axis and is provided at the tip of a robot arm of the articulated robot, a second step of emitting a guide laser beam from the laser head, and a third step of judging whether or not the distance between the irradiation position of the guide laser beam on the gauge and a reference point is within a predetermined range. If the judgment result in the third step is negative, the position of the laser head relative to the hand shaft is adjusted, and the process returns to the first step and repeats a series of steps until the judgment result in the third step becomes positive.

[0003] Patent Document 2 discloses a laser processing method in which a processing laser beam emitted from a processing laser oscillator is irradiated onto a surface of a workpiece through a focusing optical system having a focusing lens. A visible laser oscillator capable of irradiating two or more visible laser beams is provided on the processing laser oscillator side of the focusing lens. In addition, a correlation graph is created in advance in which the correlation value is maximum when the focal position of the processing laser and the focal position of each visible laser completely coincide with each other, and the correlation value decreases according to the deviation amount of the focal position of each visible laser. In the correlation graph, the allowable deviation amount of the focal position of each visible laser allowed during processing is set in advance. The focal light of each visible laser is captured by an imaging device and image processed, and it is determined whether the deviation amount of the focal position of each visible laser is within the range of the allowable deviation amount of the correlation graph. If the focal positions of both laser beams are outside the range of the allowable deviation amount, the focusing lens and the visible laser oscillator are adjusted forward and backward in synchronization. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent No. 7113201 [Patent Document 2] Japanese Patent No. 4594256 Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure has been devised in consideration of the conventional circumstances, and aims to provide a method for adjusting the focal position of laser light that simply and easily adjusts the focal position of laser light in the thickness direction of a workpiece. [Means for solving the problem]

[0006] The present disclosure provides a method for adjusting a focal position of a laser beam, which is executed by a laser processing apparatus including at least a laser oscillator that generates a laser beam and a guide laser beam, and a laser head that irradiates each of the laser beam and the guide laser beam downward, and includes a first step of inserting a first holder that holds a protective glass that transmits the guide laser beam and an aperture that limits a beam diameter of the guide laser beam, into an insertion hole provided in a lower part of the laser head, a second step of irradiating the guide laser beam, and a third step of determining, during execution of the second step, whether or not the focal position of the laser beam is within a predetermined range including the reference position along the irradiation direction of the laser beam, based on a comparison between a test piece provided at a reference position corresponding to the focal position of the guide laser beam and the beam diameter of the guide laser beam displayed on the test piece. Effect of the Invention

[0007] According to the present disclosure, adjustment of the focal position of laser light in the thickness direction of the workpiece can be easily and simply performed. [Brief description of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing a configuration example of a laser processing device according to an embodiment of the present invention. [Diagram 2] An external view showing an example of how the protective glass holder is inserted into the insertion hole at the bottom of the laser head. [Diagram 3] FIG. 1 is a schematic diagram showing an example of a configuration of a laser head having a block structure. [Figure 4] A plan view of the protective glass holder inserted into the insertion hole at the bottom of the laser head in normal processing mode, viewed in the Z direction. [Diagram 5] Plan view of the first jig holder inserted into the lower laser head insertion hole in the maintenance mode, viewed in the Z direction [Figure 6] FIG. 13 is a diagram showing an example of the focal position when a first jig holder corresponding to a different focal length for each imaging ratio specification of the laser processing system is inserted during the maintenance mode. [Figure 7] FIG. 13 is a diagram showing an example of the beam diameter of the guide laser light when the focal position of the guide laser light on the sensor card is not correctly adjusted. [Figure 8] FIG. 13 is a diagram showing an example of the beam diameter of the guide laser light when the focal position of the guide laser light on the sensor card is correctly adjusted. [Figure 9] 1 is a flowchart showing an example of a procedure for adjusting the focal position of a laser beam by a laser control unit in a maintenance mode in a chronological order. [Figure 10] FIG. 13 shows an example of the focal position when a second jig holder is inserted according to the imaging ratio in another laser processing system during the maintenance mode. [Figure 11] A diagram showing an example of the focal position when the third jig holder is inserted according to the imaging ratio in another laser processing system during the maintenance mode. [Figure 12] 1 is a flowchart showing an example of a procedure for adjusting the focal position of a laser beam by a laser control unit in a maintenance mode in a chronological order. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] (Background to this disclosure) A technology for performing laser processing while moving a laser head using a robot is widely known. In order to perform the desired laser processing, it is necessary to match the focal position of the laser light emitted from the laser head with the focal position of the laser light set in the robot or its control unit. In particular, in laser processing, fluctuations in the incidence characteristics of the laser light emitted from the laser head at the processing point (i.e., the point on the workpiece where the laser light is irradiated) have a significant effect on the processing results. On the other hand, at the laser processing site, there are limited means for checking the incidence characteristics of the laser light at the processing point, and in order to perform strict characteristic measurements, expensive equipment such as a known focal position measuring device is required.

[0010] As mentioned above, in the case of 3D laser processing using a robot manipulator, it is necessary to match the coordinates of the focal position of the laser light with the coordinates of the focal position recognized by the robot, but there is a demand for this adjustment to be performed cheaply and quickly at the laser processing site. In particular, with the recent advancement of laser processing technology, various characteristics of light sources such as laser oscillators, propagation characteristics of laser heads, and construction methods have been established, but the current situation is that adjustment of the processing point is often performed at the laser processing site or by skilled workers.

[0011] In the configuration of Patent Document 1, it is possible to adjust the focal position of the laser light along the horizontal plane (in other words, the XY plane), but it is difficult to adjust the focal position of the laser light in the thickness direction of the workpiece (in other words, the Z direction).In the configuration of Patent Document 2, it is necessary to provide a visible laser oscillator that oscillates the visible laser and a CCD camera (imaging device) in a housing equivalent to the laser head, and this inevitably leads to an increase in cost due to the larger size of the laser head, and also makes it cumbersome to prepare in advance a correlation graph between the focal position of the processing laser and the focal position of the visible laser for each laser head.

[0012] Hereinafter, an embodiment of a laser beam focal position adjusting method and a laser processing apparatus that simply and easily adjust the focal position of a laser beam in the thickness direction of a workpiece will be described.

[0013] Hereinafter, with reference to the drawings as appropriate, an embodiment specifically disclosing the laser beam focal position adjustment method and the laser processing apparatus according to the present disclosure will be described in detail. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters and duplicate explanation of substantially the same configuration may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to facilitate understanding by those skilled in the art. Note that the attached drawings and the following explanation are provided to enable those skilled in the art to fully understand the present disclosure, and are not intended to limit the subject matter described in the claims.

[0014] 1. Definitions In the following description, unless otherwise expressly stated, the term "laser processing" has the broadest possible meaning, and "processing" may be replaced with "welding", which includes the processes of soldering, melting, joining, annealing, softening, tackifying, resurfacing, peening, heat treating, fusing, sealing, stacking, and cutting.

[0015] 2. Configuration of laser processing equipment First, with reference to FIG. 1, the configuration of a laser processing apparatus 100 according to the present embodiment will be described.

[0016] FIG. 1 is a schematic diagram showing a configuration example of a laser processing apparatus 100 according to the present embodiment. In the following description, the directions referred to in the description of the laser processing apparatus 100 are defined by the directions shown in each drawing. Specifically, the traveling direction of the laser light LB in the optical unit 20 is sometimes referred to as the X direction, and the direction intersecting with the X direction on the surface of the workpiece 200 shown in FIG. 1 is sometimes referred to as the Y direction. The directions intersecting with each of the X direction and the Y direction are sometimes referred to as the Z direction. In addition, in a state where the manipulator 40 is stationary in the posture shown in FIG. 1, the side where the laser head 60 is arranged in the Z direction may be referred to as the upper side or upper side, and the side where the workpiece 200 is arranged with respect to the laser head 60 may be referred to as the lower side or lower side. In addition, in a state where the manipulator 40 is in the same state, in the X direction, the side where the laser head 60 is arranged may be referred to as the front side or front side, and the side where the robot arm 41 is arranged with respect to the laser head 60 may be referred to as the rear side or rear side.

[0017] 1, the laser processing apparatus 100 includes a laser oscillator 10, an optical unit 20, a manipulator 40, an optical fiber 30, and a laser head 60. The laser processing apparatus 100 further includes a controller 70 having the functions of controlling both the laser and the manipulator 40, and a teaching pendant 73 having the function of an input device that receives input operations from an operator. The laser oscillator 10 and the manipulator 40 are each connected to the controller 70.

[0018] The laser oscillator 10 generates the laser light LB or the guide laser light GLB based on a command from the laser control unit 71 of the controller 70, and emits it toward the optical unit 20. For example, in this embodiment, the operation mode of the laser processing device 100 is set by the laser control unit 71. There are a normal processing mode and a maintenance mode as the operation modes. The details of each mode will be described later, but in the normal processing mode, the laser light LB is generated, and in the maintenance mode, the guide laser light GLB is generated. In this embodiment, the wavelength of the laser light LB is, for example, about 900 nm to 1000 nm, and the output is, for example, on the order of 1 kW to 5 kW. However, this is not particularly limited, and each may have other values, for example, a blue laser light (blue laser beam) having a wavelength of about 400 nm to 500 nm, which is a blue wavelength band. That is, based on a command from the laser control unit 71, the laser oscillator 10 can generate a laser light of a wavelength band and output (kilowatts) corresponding to the command. The laser oscillator 10 may also include another laser light source (not shown) that emits the guide laser light GLB. The guide laser light has a wavelength of, for example, about 650 nm, which is visible light, and has an output of several mW to several tens of mW, which is significantly lower than the output of the laser light LB. The optical axis of the guide laser light is approximately aligned with the optical axis of the laser light LB.

[0019] The laser oscillator 10 may include a plurality of laser modules and a beam combiner (not shown), and may generate the laser light LB, for example, a blue laser beam. The laser oscillator 10 combines laser lights of different wavelengths (within a range of about 400 nm to 500 nm, for example, different wavelengths such as 400 nm, 420 nm, 440 nm, and 480 nm) emitted from each of the plurality of laser modules into one blue laser beam using a beam combiner. The laser oscillator 10 may be called a Direct Diode Laser (DDL) oscillator. The laser module itself is composed of a plurality of laser diodes, and is composed of, for example, a semiconductor laser array. The laser oscillator 10 is connected to a laser driving power supply (not shown), and the laser output is controlled in synchronization with the output of the laser driving power supply.

[0020] In this specification, "substantially the same" or "substantially orthogonal" refers to the fact that the objects being compared are the same or orthogonal, including the processing tolerances and assembly tolerances of each component that constitutes the laser processing apparatus 100, and does not mean that the objects being compared are the same or orthogonal in the strict sense.

[0021] The optical unit 20 has a housing 21. The optical unit 20 accommodates a condensing lens 22 inside the housing 21. The condensing lens 22 condenses the laser beam LB or the guide laser beam GLB incident into the housing 21, and makes the laser beam LB or the guide laser beam GLB incident into the optical fiber 30. In order to align the condensing position of the laser beam LB or the guide laser beam GLB with the incident end face of the optical fiber 30, the optical unit 20 may further be provided with a condensing position adjustment mechanism (not shown).

[0022] The manipulator 40 is a known vertical six-axis robot having a first joint axis J1, a second joint axis J2, a third joint axis J3, a fourth joint axis J4, a fifth joint axis J5, and a sixth joint axis J6, and the operation of each joint axis is controlled by a manipulator control unit 72 of a controller 70. The sixth joint axis J6 may be called a hand axis. The sixth joint axis J6 is provided at the tip of the robot arm 41. The sixth joint axis J6 is configured to be rotatable around a predetermined axis line RA. A cable (not shown) provided between the manipulator 40 and the controller 70 houses a cooling hose (not shown) of the laser head 60 and I / O lines (not shown) such as a thermal switch.

[0023] The optical fiber 30 is connected to the optical unit 20 and the laser head 60, and transmits the laser beam LB or the guide laser beam GLB incident from the optical unit 20 to the laser head 60. Although not shown, the optical fiber 30 has one or more cores which are waveguides for the laser beam LB or the guide laser beam GLB.

[0024] The laser head 60 is attached to the sixth joint axis J6 by the manipulator 40. The laser head 60 irradiates the laser beam LB or the guide laser beam GLB transmitted from the optical fiber 30 to the laser head 60 toward the workpiece 200. As a result, when the laser processing apparatus 100 is in the normal processing mode, the laser head 60 irradiates the laser beam LB, and the workpiece 200 is laser-processed by the laser beam LB. On the other hand, when the laser processing apparatus 100 is in the maintenance mode, the laser head 60 irradiates the guide laser beam GLB having a wavelength band different from that of the laser beam LB, and the focal position of the beam irradiated from the laser head 60 is adjusted. The details of the focal position adjustment will be described later. The laser head 60 has an optical system (e.g., a collimation lens, a condenser lens) therein (see FIG. 3), and converts the laser beam LB or the guide laser beam GLB into parallel beams, and then irradiates them downward (e.g., in the Z direction) through the condenser lens FCL1. An example of the internal structure of the laser head 60 will be described later with reference to each of FIG. 3 to FIG. 5.

[0025] The controller 70 includes a laser control unit 71 for controlling the operation of the laser oscillator 10, and a manipulator control unit 72 for controlling the operation of the manipulator 40. The controller 70 is connected to a teaching pendant 73 that is operated by an operator, and receives and acquires a signal corresponding to the content of the input operation by the operator from the teaching pendant 73.

[0026] The laser control unit 71 is configured as one of the functions of the controller 70, and is electrically connected to the laser oscillator 10. It controls the operation of the laser oscillator 10 and generates a screen showing the processing result of the laser control unit 71 and displays it on the teaching pendant 73. The laser control unit 71 also controls the operation of a laser driving power supply (not shown) connected to the laser oscillator 10. Specifically, the laser oscillator 10 controls the output of the laser light LB, the oscillation time, and the timing of starting and stopping the oscillation of the laser light LB or the guide laser light GLB based on the control (command) of the laser control unit 71.

[0027] The laser control unit 71 also includes a control board for managing and controlling, for example, the operation modes (e.g., normal processing mode, maintenance mode) of the laser processing apparatus 100. A processor 71a and a memory 71b are mounted on this control board. Although not shown in FIG. 1, the laser control unit 71 may be provided as a separate configuration from the controller 70. In this case, the laser control unit 71 and the laser oscillator 10 are electrically connected by wiring or the like, and electrical connection between the controller 70 and the laser oscillator 10 is not required.

[0028] Here, there will be explained the operation modes of the laser processing apparatus 100. As described above, the operation modes include the normal processing mode and the maintenance mode.

[0029] The normal processing mode is an operating mode in which, after adjustment of the focal position of the laser light irradiated from the laser head 60 and confirmation of the operating program in the maintenance mode are completed, laser light LB is generated from the laser oscillator 10 and laser processing is performed on the workpiece 200 via the optical unit 20, the optical fiber 30 and the laser head 60.

[0030] The maintenance mode is an operation mode in which the guide laser light GLB is generated without generating the laser light LB from the laser oscillator 10, and the guide laser light GLB is used to adjust the focal position of the laser light irradiated from the laser head 60, check the operation program, and perform various maintenance (e.g., replacing the protective glass of the laser head, etc.). In this embodiment, the focal position can be adjusted by adjusting the vertical (e.g., Z direction) position of an optical element (e.g., collimation lens CLL1) arranged in the laser head 60, in other words, the distance (length) from the top of the laser head 60 to which the optical fiber 30 is connected to the collimation lens CLL1.

[0031] The processor 71a manages and controls whether the operation mode of the laser processing apparatus 100 is a normal processing mode or a maintenance mode. In the normal processing mode, the processor 71a commands the laser oscillator 10 to oscillate (generate) a laser beam LB having a predetermined frequency band and output. On the other hand, in the maintenance mode, the processor 71a commands the laser oscillator 10 to oscillate (generate) a guide laser beam GLB having a predetermined frequency band and output. For example, in response to detection of an input operation from a teaching pendant 73 used by an operator, the processor 71a may switch to an operation mode according to the content of the input operation or send an output command for the guide laser beam GLB. In addition, the processor 71a may generate a screen indicating that the laser processing in the normal processing mode has been completed and display it on the teaching pendant 73, or generate a screen indicating that the adjustment of the focal position of the laser beam in the maintenance mode has been completed and display it on the teaching pendant 73.

[0032] The memory 71b includes a Random Access Memory (RAM) and a Read Only Memory (ROM). The RAM temporarily stores data or information acquired or generated by the processor 71a. The ROM stores programs and data used for various processes executed by the processor 71a.

[0033] The manipulator control unit 72 is configured as one of the functions of the controller 70, is electrically connected to the manipulator 40, and controls the operation of the manipulator 40. Specifically, the manipulator control unit 72 controls the movement speed and movement amount of the laser head 60 connected to the manipulator 40 by controlling the rotation speed and rotation amount of motors (not shown) connected to the first joint axis J1 to the sixth joint axis J6, respectively.

[0034] The manipulator control unit 72 controls the operation of the manipulator 40 based on a previously prepared operation program or parameters input from a teaching pendant 73. The manipulator control unit 72 also sets and stores the focal position of the laser light LB emitted from the laser head 60.

[0035] The teaching pendant 73 is a device used to store a predetermined operation in the manipulator control unit 72. An operator actually operates the manipulator 40 using the teaching pendant 73, and stores various parameters (for example, the rotation amount from one teaching point to the next teaching point of the motors (not shown) connected to each of the first joint axis J1 to the sixth joint axis J6) in the manipulator control unit 72. The teaching pendant 73 may cause the manipulator 40 to execute the operation stored in the manipulator control unit 72 again, and, if necessary, may finely correct various parameters using the teaching pendant 73 and store them again in the manipulator control unit 72. The teaching pendant 73 may include, for example, a Liquid Crystal Display (LCD) or an organic electroluminescence (EL) display, and display a screen showing the processing results by the laser control unit 71 or the processing results by the manipulator control unit 72.

[0036] 3. Laser head structure Next, the structure of the laser head 60 of the laser processing apparatus 100 according to this embodiment will be described with reference to FIGS.

[0037] Fig. 2 is an external view showing an example of a state when the protective glass holder SH1 is inserted into the laser head lower insertion hole HL1. Fig. 3 is a diagram showing a schematic configuration example of the laser head 60 having a block structure. Fig. 4 is a plan view of the protective glass holder SH1 inserted into the laser head lower insertion hole HL1 in the normal processing mode when viewed in the Z direction. Fig. 5 is a plan view of the first jig holder SH2 inserted into the laser head lower insertion hole HL1 in the maintenance mode when viewed in the Z direction.

[0038] As shown in Fig. 2, a laser head lower insertion hole HL1 formed of a rectangular parallelepiped gap is provided on the lower end side of the laser head 60. In the normal processing mode, a protective glass holder SH1 is inserted into this laser head lower insertion hole HL1, and in the focus adjustment operation, any one of the first jig holder SH2 (see Fig. 5), the second jig holder SH2a (see Fig. 10), and the third jig holder SH2b (see Fig. 11) is inserted. In the example of Fig. 2, a state in which the protective glass holder SH1 on which the protective glass SG1 is placed so as to be able to be held is shown to be inserted.

[0039] As shown in FIG. 3, the laser head 60 is configured by connecting a plurality of different blocks BLK1 to BLK6 in a vertically detachable manner. Adjacent blocks may be connected and fixed by connecting end faces formed in the vertical circumferential direction of the blocks with a known fixing mechanism such as a fastener such as a screw or a magnet. For example, the block BLK1 is a substantially cylindrical structure that is trapezoidal in side view cut in the Z direction, and the blocks BLK1 and BLK2 can be connected and fixed by engaging an engaged portion (not shown) provided below the block BLK1 with an engaging hole (not shown) provided above the block BLK2. The blocks BLK2 and BLK3 are cylindrical structures that are rectangular in side view cut in the Z direction, and the blocks BLK2 and BLK3 can be connected and fixed by engaging an engaged portion (not shown) provided below the block BLK2 with an engaging hole (not shown) provided above the block BLK3. The other blocks are connected and fixed in the same manner, so a description thereof will be omitted.

[0040] Although not shown in Fig. 3, after adjacent blocks are fixed to each other, the laser beam LB or the guide laser beam GLB guided into the laser head 60 passes between the connected and fixed blocks without attenuation and advances downward. In the illustrated example of Fig. 3, six blocks BLK1 to BLK6 are shown connected in the up-down direction, but the number of blocks constituting the laser head 60 is not limited to six, and may be less than six or more than six.

[0041] The block BLK1 is a block that accommodates a connection part CN1 that is connected to the optical fiber 30 and has a function of guiding the laser beam LB or the guide laser beam GLB0 from the optical fiber 30.

[0042] The block BLK2 contains a collimation lens CLL1 which constitutes a part of the optical elements of the laser head 60 and has a function of collimating the laser beam LB or the guide laser beam GLB0 from the optical fiber 30. The vertical position of the collimation lens CLL1 determines the focal position of the laser beam LB or the guide laser beam GLB emitted from the laser head 60. Therefore, in this embodiment, when the focal position of the laser beam LB or the guide laser beam GLB is not appropriate, the vertical position of the collimation lens CLL1 in the laser head 60 is changed to adjust the focal position.

[0043] In the example of Figure 3, the block BLK3 is a block that does not contain any optical elements such as lenses, but it may be a block that contains an optical element such as a focusing lens different from the collimation lens CLL1 to adjust the focal position of the laser light LB or the guide laser light GLB.

[0044] The block BLK4 is a block that contains a condenser lens FCL1 that constitutes a part of the optical elements of the laser head 60 and condenses the laser beam LB or the guide laser beam GLB collimated by the collimation lens CLL1 toward a desired focal position. Note that, in order to simply explain the configuration of the optical elements inside the laser head 60, only one condenser lens other than the collimation lens CLL1 is illustrated, but a configuration using multiple condenser lenses may be used.

[0045] The block BLK5 is a block that houses a laser head lower insertion hole HL1 into which any one of the protective glass holder SH1, the first jig holder SH2, the second jig holder SH2a, and the third jig holder SH2b can be inserted and removed. Details of each holder will be described later.

[0046] The block BLK6 is a block that is located at the bottom of the laser head 60 and has a function as a nozzle that irradiates the laser beam LB or the guide laser beam GLB transmitted through the condenser lens FCL1.

[0047] 3, the laser head 60 is configured by connecting a plurality of different blocks BLK1 to BLK6 in a detachable manner in the vertical direction, but the configuration is not limited to this. That is, the laser head 60 according to the present embodiment may be configured to have a single housing in which a plurality of different blocks are integrated, instead of a structure in which a plurality of different blocks are connected.

[0048] FIG. 4 shows a plan view of the protective glass holder SH1 inserted into the laser head lower insertion hole HL1 of the laser head 60 in the normal processing mode when viewed in the Z direction. The protective glass holder SH1 has a holding recess 51 for holding and fixing the protective glass SG1 placed thereon. That is, the protective glass holder SH1 has a holding recess 51 formed by cutting out a part so that the protective glass SG1 is not released from the protective glass holder SH1 in the normal processing mode. Therefore, the protective glass SG1 is held and fixed by the holding recess 51, so that the protective glass SG1 does not fall during the normal processing mode. The protective glass SG1 has a role of protecting the laser head 60 from scattered deposits such as fumes or spatters generated from the workpiece 200 by irradiation of the laser light LB from the laser head 60 to the workpiece 200 (i.e., laser processing) during the normal processing mode.

[0049] 5 shows a plan view of the first jig holder SH2 inserted into the laser head lower insertion hole HL1 of the laser head 60 during the maintenance mode, as viewed in the Z direction. The first jig holder SH2 is configured such that a cover member 50 (that is, an aperture APR1 that is an opening that limits and transmits a part of the guide laser light GLB) is disposed above the protective glass SG1. As with the protective glass holder SH1, the first jig holder SH2 is also provided with a holding recess 51 for holding and fixing the protective glass SG1 and the aperture APR1. Therefore, by holding and fixing the protective glass SG1 and the cover member 50 by the holding recess 51, the protective glass SG1 and the cover member 50 do not fall during the maintenance mode. Furthermore, by forming the aperture APR1 in the first jig holder SH2, the beam diameter of the guide laser light GLB passing through the aperture APR and the protective glass SG1 during the maintenance mode is smaller than the beam diameter of the laser light LB or the guide laser light GLB passing through the protective glass SG1 during the normal processing mode.

[0050] 4. Focus position adjustment (first mode: adjusting the focal position according to the configuration of the imaging ratio of the system) Next, a method for adjusting the focal position of the laser beam LB or the guide laser beam GLB according to the configuration of the imaging ratio based on the optical element in the laser head 60 of the own system will be described with reference to Figs. 6 to 8. Fig. 6 is a diagram showing an example of the focal position when the first jig holder SH2 corresponding to the focal length different for each imaging ratio specification in the own laser processing system is inserted during the maintenance mode. Fig. 7 is a diagram showing an example of the beam diameter of the guide laser beam GLB when the focal position of the guide laser beam GLB on the sensor card SCD1 is not properly adjusted, for example. Fig. 8 is a diagram showing an example of the beam diameter of the guide laser beam GLB when the focal position of the guide laser beam GLB on the sensor card SCD1 is properly adjusted, for example. The sensor card SCD1 is an example of a test piece, and may be replaced by an iron plate or paper on which a circle of a specified size is printed.

[0051] As shown in Fig. 6, when adjusting the vertical focal position of the laser beam LB used in the normal processing mode of the own laser processing system (i.e., the laser processing apparatus 100 in Fig. 1), in the maintenance mode, the first jig holder SH2 is inserted into the laser head lower insertion hole HL1. The dashed line LB0 in Fig. 6 indicates the laser beam that is transmitted through the focusing lens FCL1 and focused when the vertical position of the collimation lens CLL1 in the laser head 60 is adjusted correctly, that is, the laser beam whose focal position is adjusted correctly. Therefore, when the focal position of the laser beam is adjusted correctly, the focal position of the laser beam is located at position Z1 (see the guide laser beam GLB0).

[0052] In the maintenance mode, a low-power guide laser beam GLB is used instead of the high-power laser beam GB used in actual laser processing, and the vertical position of the collimation lens CLL1 is changed so that the focal position of the guide laser beam GLB is at position Z1. Specifically, the sensor card SCD1 shown in each of Figs. 7 and 8 is placed at this position Z1. Since a low-power and safe guide laser beam GLB is used, the sensor card SCD1 may be held by an operator or may be placed on a flat plate-like object (not shown).

[0053] An absorber Th1, such as a black body, having a circular cross section when viewed in the XY plane is disposed on the sensor card SCD1 shown in each of Fig. 7 and Fig. 8. The absorber Th1 has a property of absorbing the guide laser beam GLB.

[0054] (1) Assume that the inner diameter d2 indicating the beam diameter of the guide laser beam GLB absorbed by the absorber Th1 is measured by visual inspection or the like to be smaller than the inner diameter d1 of the absorber Th1 (d2 < d1, see Fig. 7). In this case, it is determined that the beam diameter (d2) of the guide laser beam GLB is smaller than the inner diameter d1 that serves as a threshold value, and the focus of the guide laser beam GLB at the position Z1 in the Z direction is not correctly adjusted. In other words, the beam diameter of the guide laser beam GLB at the position Z1 deviates greatly from the focus position of the laser beam LB in the normal processing mode. Therefore, in this case, assuming that the position of the collimation lens CLL1 in the Z direction within the laser head 60 is not correctly adjusted, the position of the collimation lens CLL1 in the Z direction is continuously changed (adjusted) automatically or manually by an operator or the like until an inner diameter d3 larger than the inner diameter d1 described later is measured.

[0055] (2) Assume that the inner diameter d3 indicating the beam diameter of the guide laser beam GLB absorbed by the absorber Th1 is measured by visual inspection or the like to be larger than the inner diameter d1 of the absorber Th1 (d3 > d1, see Fig. 8). In this case, it is determined that the beam diameter (d3) of the guide laser beam GLB is larger than the inner diameter d1 that serves as a threshold value, and the focus of the guide laser beam GLB at the position Z1 in the Z direction is correctly adjusted. In other words, the beam diameter of the guide laser beam GLB at the position Z1 is in a state where it can be considered to be approximately equivalent to the focus position of the laser beam LB in the normal processing mode. Therefore, in this case, since the position of the collimation lens CLL1 in the Z direction within the laser head 60 is correctly adjusted, the current position of the collimation lens CLL1 in the Z direction is held (maintained).

[0056] 5. Operating Procedure for Focus Position Adjustment (First Example) Next, an operation procedure (first example) of the method for adjusting the focal position of laser light using the laser processing apparatus 100 of this embodiment will be described with reference to Fig. 9. Fig. 9 is a flowchart showing a chronological example of the procedure for adjusting the focal position of the laser light LB in the maintenance mode by the laser control unit 71. As described above, in the maintenance mode, the low-power guide laser light GLB is used instead of the high-power laser light LB when adjusting the focal position.

[0057] 9, the processor 71a of the laser control unit 71 judges whether the current operation mode is the maintenance mode or not by referring to the memory 71b etc. (step St1). When the processor 71a judges that the current operation mode is not the maintenance mode (i.e., the normal processing mode) (step St1, NO), it generates a screen to that effect and displays it on the teaching pendant 73. For example, an operator who sees this screen display inserts the protective glass holder SH1, in which only the protective glass SG1 is fixed by the holding recess 51, into the laser head lower insertion hole HL1 of the laser head 60 (step St2). Note that if the protective glass holder SH1 has already been inserted into the laser head lower insertion hole HL1 at the time of executing step St2, the processing of step St2 may be omitted.

[0058] After detecting that the process of step St2 has been completed by the operator through an input operation using the teaching pendant 73, the processor 71a causes the laser oscillator 10 to oscillate (generate) a high-power laser beam LB to be used in the normal processing mode (step St3). After the laser beam LB is oscillated in step St3, the laser control unit 71 executes laser processing of the workpiece 200, which is the object to be processed, according to a processing program (not shown) previously prepared for laser processing (step St4). After step St4, if the processor 71a does not determine that the operation mode is to be switched to the maintenance mode through, for example, an input operation using the teaching pendant 73 by the operator (step St5, NO), the process of the processor 71a shown in FIG. 9 ends.

[0059] On the other hand, when the processor 71a determines that the operation mode is to be switched to the maintenance mode by, for example, an input operation using the teaching pendant 73 by the operator (YES in step St5, YES in step St1), it generates a screen to that effect and displays it on the teaching pendant 73. For example, the operator who sees this screen display inserts the first jig holder SH2, in which the cover member 50 is placed on the protective glass SG1 to form the aperture APR1 and is fixed by the holding recess 51, into the laser head lower insertion hole HL1 of the laser head 60 (step St6). Note that, if the first jig holder SH2 has already been inserted into the laser head lower insertion hole HL1 at the time of executing step St6, the processing of step St6 may be omitted.

[0060] After detecting that the process of step St6 has been completed by an input operation by an operator using the teaching pendant 73, the processor 71a causes the laser oscillator 10 to oscillate (generate) the low-power guide laser light GLB used in the maintenance mode (step St7). After step St7, the operator visually or otherwise determines whether the focal length of the guide laser light GLB (in other words, the focal length of the laser light LB) is appropriate (step St8). For example, as described with reference to FIG. 7 and FIG. 8, in a state where the first jig holder SH2 is inserted, the sensor card SCD1 and the absorber Th1 are placed at a position Z1 corresponding to a desired focal position, and it is determined by visual or otherwise whether the inner diameter of the beam diameter of the guide laser light GLB at the position Z1 is larger than the inner diameter d1 of the absorber Th1 at the same position Z1. Here, the visual determination is used to simplify the description, but the processor 71a may automatically determine by analysis using an image captured by a camera (not shown) arranged to capture the state of FIG. 7 and FIG. 8.

[0061] When it is determined that the focal length of the guide laser beam GLB (in other words, the focal length of the laser beam LB) is not appropriate (step St8, NO), the position of the collimation lens CLL1 in the laser head 60 emitting the guide laser beam GLB is not adjusted correctly to a degree that a desired focal position can be obtained. For this reason, the Z-direction position adjustment of the collimation lens CLL1 is performed by an operator (step St9). Note that, for the sake of simplicity, the Z-direction position adjustment of the collimation lens CLL1 is performed manually by an operator here, but the Z-direction position adjustment may be performed automatically by a motor (not shown) or the like. After step St9, when the processor 71a detects that the position of the collimation lens CLL1 has been adjusted by an input operation by the operator using a mouse or the like, the processor 71a resumes the process of step St7. That is, in the maintenance mode, the processes of steps St7 to St9 are repeatedly performed until the focal position of the guide laser beam GLB (in other words, the laser beam LB) is adjusted correctly.

[0062] On the other hand, if it is determined that the focal length of the guide laser beam GLB (in other words, the focal length of the laser beam LB) is appropriate (step St8, YES), the processor 71a detects this through an input operation by the operator using the teaching pendant 73, and determines that the reference focal position is established (step St10). This ends the process of the processor 71a shown in FIG.

[0063] 6. Focus position adjustment (Second mode: Adjustment of the focal position according to the configuration of the imaging ratio of other systems) Next, a method for adjusting the focal position of the laser beam LB or the guide laser beam GLB according to the configuration of the imaging ratio required in another system different from the laser processing apparatus 100 shown in Fig. 1 will be described with reference to Fig. 10 and Fig. 11. Fig. 10 is a diagram showing an example of the focal position when a second jig holder SH2a according to the imaging ratio in another laser processing system is inserted during the maintenance mode. Fig. 11 is a diagram showing an example of the focal position when a third jig holder SH2b according to the imaging ratio in another laser processing system is inserted during the maintenance mode.

[0064] As shown in Fig. 10, it is assumed that the imaging ratio (in other words, focal length f1 corresponding to the length from the bottom end of the laser head to focal position Z2) used in another laser processing system different from the own laser processing system (i.e., laser processing apparatus 100 in Fig. 1) is longer than the imaging ratio (in other words, focal length f0 corresponding to the length from the bottom end of the laser head 60 to position Z1 corresponding to the focal position) of the own laser processing system in Fig. 6 (f1>f0). The dashed line LB1 in Fig. 10 indicates the laser light that has been passed through the focusing lens FCL1a and focused in the other laser processing system in which the focusing lens FCL1a is arranged, that is, the laser light with the long focal length f1 and the focal position correctly adjusted.

[0065] Specifically, a block BLK7 accommodating a condenser lens FCL1a arranged in a laser head of another laser processing system is arranged in place of a block BLK4 (see FIG. 3) of a laser head 60 of the own laser processing system. Furthermore, a second jig holder SH2a is inserted into a laser head lower insertion hole HL1 of the laser head 60. In the second jig holder SH2a, a condenser lens FCL2a having optical characteristics such as a curvature for condensing the guide laser beam GLB transmitted through the condenser lens FCL1a at a position Z1 and an aperture APR1 based on a similar cover member 50 (see FIG. 5) are arranged thereon. In the maintenance mode, the guide laser beam GLB transmitted through the condenser lens FCL1a is condensed at a position Z1 by transmitting through the aperture APR1 and the condenser lens FCL2a of the second jig holder SH2a (see guide laser beam GLB0). Depending on the degree of focusing at this position Z1 (see comparison of beam diameters on the sensor card SCD1 in FIGS. 7 and 8), it is determined whether or not the position of the collimation lens CLL1 in the laser head 60 is correctly adjusted.

[0066] As shown in Fig. 11, assume a case where the imaging ratio (in other words, the focal length f2 corresponding to the length from the lower end of the laser head to the focal position Z3) adopted in another laser processing system different from the own laser processing system (that is, the laser processing apparatus 100 in Fig. 1) is shorter than the imaging ratio of the own laser processing system in Fig. 6 (in other words, the focal length f0 corresponding to the length from the lower end of the laser head 60 to the position Z1 corresponding to the focal position) (f2 < f0). The dashed line LB2 in Fig. 11 indicates the laser light that has passed through and been focused by the condenser lens FCL1b in another laser processing system where the condenser lens FCL1b is disposed, that is, the laser light with the focal position having the short focal length f2 correctly adjusted.

[0067] Specifically, a block BLK8 that houses the condenser lens FCL1b disposed in the laser head of another laser processing system is replaced with the block BLK4 (see Fig. 3) of the laser head 60 of the own laser processing system. Further, a third jig holder SH2b is inserted into the laser head lower insertion hole HL1 of the laser head 60. On the third jig holder SH2b, a condenser lens FCL2b having optical characteristics such as curvature for focusing the guide laser light GLB that has passed through the condenser lens FCL1b to the position Z1 and an aperture APR1 based on a similar lid member 50 (see Fig. 5) are disposed and formed thereon. In the maintenance mode, the guide laser light GLB that has passed through the condenser lens FCL1b passes through the aperture APR1 and the condenser lens FCL2b of the third jig holder SH2b, and is focused at the position Z1 (see the guide laser light GLB0). Based on the degree of focusing at this position Z1 (refer to the beam diameter comparison on the sensor card SCD1 in Figs. 7 and 8), it is determined whether the position of the collimation lens CLL1 in the laser head 60 is correctly adjusted.

[0068] In addition, according to this embodiment, it is possible to correct the focus deviation caused by the thermal lens effect based on the heat of the optical element. In other words, by designing the lens taking into account the focus shift amount caused by the thermal lens effect for each output used during laser processing (in other words, the rated output of the laser oscillator 10 used), it is possible to reduce the deviation amount between the focal length of the guide laser light during adjustment in the maintenance mode and the focal length of the laser light with the actual output light in the normal processing mode.

[0069] According to the present embodiment, in order to take care of the wavelength difference between the guide laser beam used in the maintenance mode and the laser beam used in the normal processing mode, the guide laser beam and the processing laser beam have different wavelengths, and the lens is designed taking the wavelength difference into consideration, thereby reducing the amount of deviation in the focal length between the guide laser beam and the processing laser beam.

[0070] 7. Operation procedure for adjusting the focal position (second example) Next, an operation procedure (second example) of the method for adjusting the focal position of laser light using the laser processing apparatus 100 of this embodiment will be described with reference to Fig. 12. Fig. 12 is a flowchart showing a chronological example of the procedure for adjusting the focal position of laser light in the maintenance mode by the laser control unit 71. As described above, in the maintenance mode, the low-power guide laser light GLB is used instead of the high-power laser light LB when adjusting the focal position. In addition, in the description of Fig. 12, the same processes as those in Fig. 9 are given the same step numbers, and the description is simplified or omitted, and different contents will be described.

[0071] 12, the processor 71a generates a screen indicating that the processing of step St10 has been completed (i.e., the reference focal position has been determined) and displays it on the display DP1. For example, an operator who has seen this screen display inserts the second jig holder SH2a, in which the lid member 50 is placed on the condenser lens FC2a to form the aperture APR1 and fixed in the holding recess 51, or the third jig holder SH2b, in which the lid member 50 is placed on the condenser lens FC2b to form the aperture APR1 and fixed in the holding recess 51, into the laser head lower insertion hole HL1 of the laser head 60 (step St21). Note that if the second jig holder SH2a or the third jig holder SH2b has already been inserted into the laser head lower insertion hole HL1 at the time of executing step St21, the processing of step St21 may be omitted.

[0072] After detecting that the process of step St21 has been completed by an input operation by an operator using a mouse or the like, the processor 71a causes the laser oscillator 10 to oscillate (generate) the low-power guide laser light GLB used in the maintenance mode (step St22). After step St22, the operator visually or otherwise determines whether the focal length of the guide laser light GLB (in other words, the focal length of the laser light LB) is appropriate (step St23). For example, as described with reference to FIG. 7 and FIG. 8, in a state in which the second jig holder SH2a or the third jig holder SH2b is inserted, the sensor card SCD1 and the absorber Th1 are placed at a position Z1 corresponding to a desired focal position, and it is determined by visual or otherwise whether the inner diameter of the beam diameter of the guide laser light GLB at the position Z1 is larger than the inner diameter d1 of the absorber Th1 at the same position Z1. Here, the visual determination is used to simplify the description, but the processor 71a may automatically determine by analysis using an image captured by a camera (not shown) arranged to capture the state of FIG. 7 and FIG. 8.

[0073] When it is determined that the focal length of the guide laser beam GLB (in other words, the focal length of the laser beam LB) is not appropriate (step St23, NO), the position of the collimation lens CLL1 in the laser head 60 emitting the guide laser beam GLB is not adjusted correctly to a degree that a desired focal position can be obtained. For this reason, the Z-direction position adjustment of the collimation lens CLL1 is performed by an operator (step St24). Note that, for the sake of simplicity, the Z-direction position adjustment of the collimation lens CLL1 is performed manually by an operator here, but the Z-direction position adjustment may be performed automatically by a motor (not shown) or the like. After step St24, when the processor 71a detects that the position of the collimation lens CLL1 has been adjusted by an input operation by the operator using a mouse or the like, the processor 71a resumes the process of step St22. That is, in the maintenance mode, the processes of steps St22 to St24 are repeatedly performed until the focal position of the guide laser beam GLB (in other words, the laser beam LB) is adjusted correctly.

[0074] On the other hand, when it is determined that the focal length of the guide laser beam GLB (in other words, the focal length of the laser beam LB) is appropriate (step St23, YES), the processor 71a detects that fact by an input operation by the operator using a mouse or the like, and determines that the reference focal position is fixed. This ends the process of the processor 71a shown in FIG.

[0075] <About the technology disclosed herein> As described above, the present disclosure discloses the following technical ideas.

[0076] <Technology 1> a laser oscillator (laser oscillator 10) that generates a laser beam (laser beam LB) and a guide laser beam (guide laser beam GLB); a laser head (laser head 60) that irradiates each of the laser beam and the guide laser beam downward, the laser beam focal position adjustment method being executed by a laser processing apparatus (laser processing apparatus 100) including at least the laser head (laser head 60), a first step of inserting a first holder (protective glass holder SH1) that holds a protective glass (protective glass SG1) that transmits the guide laser beam and an aperture (aperture APR1) that limits a beam diameter of the guide laser beam into an insertion hole (laser head lower insertion hole HL1) provided in a lower portion of the laser head; a second step of irradiating the guide laser beam; and a third step of determining whether or not the focal position of the laser beam is within a predetermined range including the reference position along the irradiation direction of the laser beam based on a comparison between a test piece (sensor card SCD1) provided at a reference position (position Z1) corresponding to the focal position of the guide laser beam and a beam diameter (inner diameters d2, d3) of the guide laser beam displayed on the test piece during the execution of the second step. A method for adjusting the focal position of a laser beam. As a result, according to the method for adjusting the focal position of laser light, it is possible to safely adjust the focal position by using the low-power guide laser light GLB instead of the high-power laser light LB, and it is possible to easily and simply adjust the focal position of the laser light in the thickness direction (in other words, the Z direction) of the workpiece, which is the object to be processed in normal processing mode.

[0077] <Technology 2> If the result of the determination in the third step is negative, a fourth step of adjusting a position of an optical element (collimation lens CLL1) provided in the laser head in the irradiation direction is further included. The method for adjusting the focal position of laser light according to Technology 1. As a result, when the beam diameter of the guide laser light GLB displayed on the sensor card SCD1 is not within the desired range (i.e., a range larger than the inner diameter d1 and smaller than the diameter of the sensor card SCD1), the focal position of the guide laser light GLB in the Z direction can be appropriately adjusted by adjusting the position of the collimation lens CLL1 in the laser head 60.

[0078] <Technology 3> repeating the processes of the third step and the fourth step until the determination result of the third step becomes positive; The method for adjusting the focal position of laser light according to Technology 2. This allows the focal position of the guide laser beam GLB in the Z direction to be appropriately adjusted so that the beam diameter of the guide laser beam GLB displayed on the sensor card SCD1 falls within a desired range (that is, a range larger than the inner diameter d1 and smaller than the diameter of the sensor card SCD1).

[0079] <Technology 4> The laser head is formed by detachably connecting a plurality of blocks (blocks BLK1 to BLK6) each housing at least one optical element (collimation lens CLL1, focusing lens FCL1). The method for adjusting the focal position of laser light according to Technology 1. This makes it possible to arbitrarily change the configuration of the laser head 60 so as to obtain desired optical characteristics, and simplifies the adjustment work by an operator of the arrangement of optical elements within the laser head.

[0080] <Technology 5> After the result of the determination in the third step is positive, a fifth step of inserting into the laser head a second block (block BLK7) that houses a second optical element (condenser lens FCL1a) having a second focal length (focal length f1) that is longer than a first focal length (focal length f0) from a lower end of the laser head to the focal position; and a sixth step of inserting, into the insertion hole, a second holder (a second jig holder SH2a) that holds a third optical element (a focusing lens FCL2a) that focuses the guide laser beam transmitted through the second optical element at the focal position, instead of the first holder. The second holder (a second jig holder SH2a) holds the aperture. The method for adjusting the focal position of laser light according to Technology 4. This makes it possible to appropriately adjust the focal position within the laser head 60 of the laser processing system (laser processing apparatus 100) even when using an imaging ratio configuration using a laser head adopted in another laser processing system having a focal length longer than the focal length of the laser light irradiated from the laser head 60 of the laser processing system (laser processing apparatus 100).

[0081] <Technology 6> After the result of the determination in the third step is positive, a seventh step of inserting into the laser head a third block (block BLK8) that houses a third optical element (condenser lens FCL1b) having a third focal length (focal length f2) that is shorter than a first focal length (focal length f0) from a lower end of the laser head to the focal position; and an eighth step of inserting, into the insertion hole, a third holder (a third jig holder SH2b) that holds a fourth optical element (a focusing lens FCL2b) that focuses the guide laser beam transmitted through the third optical element at the focal position, instead of the first holder. The third holder (a third jig holder SH2b) holds the aperture. The method for adjusting the focal position of laser light according to Technology 4. This makes it possible to appropriately adjust the focal position within the laser head 60 of the laser processing system (laser processing apparatus 100) even when using an imaging ratio configuration using a laser head adopted in another laser processing system having a focal length shorter than the focal length of the laser light irradiated from the laser head 60 of the laser processing system (laser processing apparatus 100).

[0082] Although various embodiments have been described above with reference to the drawings, it goes without saying that the present disclosure is not limited to such examples. It is clear that a person skilled in the art can conceive of various modifications, corrections, substitutions, additions, deletions, and equivalents within the scope of the claims, and it is understood that these also naturally belong to the technical scope of the present disclosure. In addition, the components in the various embodiments described above may be arbitrarily combined within the scope of the invention.

[0083] This application is based on a Japanese patent application (Patent Application No. 2023-128780) filed on August 7, 2023, the contents of which are incorporated by reference into this application. [Industrial Applicability]

[0084] INDUSTRIAL APPLICABILITY The present disclosure is useful as a laser beam focal position adjusting method and laser processing apparatus that simply and easily adjust the focal position of a laser beam in the thickness direction of a workpiece. [Explanation of symbols]

[0085] 10 Laser Oscillator 20 Optical unit 21 Case 22 Condenser lens 23 Shutter 30 Optical Fiber 40 Manipulator 41 Robot Arm 42 Cable 50 Lid member 51 Retaining recess 60 Laser Head 71 Laser control unit 100 Laser processing equipment 200 Work APR1 Aperture BLK1, BLK2, BLK3, BLK4, BLK5, BLK6 blocks CLL1 Collimation Lens CN1 connection part FCL1 Condenser Lens GLB Guide laser light HL1 Laser head lower insertion hole LB laser light SG1 Protective Glass SH1 Protective Glass Holder SH2 1st jig holder SH2a 2nd jig holder SH2b 3rd jig holder

Claims

1. A method for adjusting a focal position of laser light, comprising the steps of: The laser processing apparatus includes at least a laser oscillator that generates a laser beam and a guide laser beam, and a laser head that irradiates each of the laser beam and the guide laser beam downward, a first step of inserting a first holder, the first holder holding a protective glass that transmits the guide laser beam and an aperture that limits a beam diameter of the guide laser beam, into an insertion hole provided in a lower portion of the laser head; a second step of irradiating the guide laser beam; and a third step of determining whether or not the focal position of the laser beam is within a predetermined range including the reference position along the irradiation direction of the laser beam, based on a comparison between a test piece provided at a reference position corresponding to the focal position of the guide laser beam and a beam diameter of the guide laser beam displayed on the test piece during the execution of the second step. A method for adjusting the focal position of a laser beam.

2. If the result of the determination in the third step is negative, a fourth step of adjusting a position of an optical element provided in the laser head in the irradiation direction is further included.

2. The method for adjusting the focal position of laser light according to claim 1.

3. repeating the processes of the third step and the fourth step until the determination result of the third step becomes positive; 3. The method for adjusting the focal position of laser light according to claim 2.

4. The laser head is formed by detachably connecting a plurality of blocks each accommodating at least one optical element.

2. The method for adjusting the focal position of laser light according to claim 1.

5. After the determination result in the third step is positive, a fifth step of inserting a second optical element into the laser head, the second optical element having a second focal length longer than a first focal length from a lower end of the laser head to the focal position; and a sixth step of inserting a second holder, which holds a third optical element that focuses the guide laser beam transmitted through the second optical element at the focal position, into the insertion hole, instead of the first holder. The second holder holds the aperture.

2. The method for adjusting the focal position of laser light according to claim 1.

6. After the determination result in the third step is positive, a seventh step of inserting a third optical element into the laser head, the third optical element having a third focal length shorter than a first focal length from a lower end of the laser head to the focal position; and an eighth step of inserting a third holder, which holds a fourth optical element that focuses the guide laser beam transmitted through the third optical element at the focal position, into the insertion hole, instead of the first holder. The fourth optical element and the third holder hold the aperture.

2. The method for adjusting the focal position of laser light according to claim 1.

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