JP2006187798A - Method and device for laser beam machining - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a device for laser beam machining, which divides a laser beam emitted from a laser beam source into a plurality of paths different from each other, and which machines a work with the laser beams which have passed through each of the paths, and which requires no optical adjustment for uniformizing the power of laser beams which have passed through each of the paths. <P>SOLUTION: The device for laser beam machining has: a directing apparatus 2 which directs a pulse laser beam emitted from a laser beam source 1 into a 1st state in which the pulse laser beam is made incident into a work 8 through a 1st path, or into a 2nd state in which the pulse laser beam is made incident into the work 8 through a 2nd path; a memorizing means 20a, which separately memorizes the 1st pulse number of the laser beams made incident in the 1st state of the directing apparatus and the 2nd pulse number of the laser beams made incident in the 2nd state of the apparatus; and a controlling device 20, which controls the laser beam source 1 so that the pulse beams are made incident into a work 8 by the 1st pulse number when the directing apparatus 2 takes the 1st state and are made incident by the 2nd pulse number when the apparatus 2 takes the 2nd state. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a laser processing apparatus and a laser processing method, and more particularly to a laser processing apparatus and a laser processing method for making a pulse laser beam incident on a processing target.

  For example, Patent Document 1 discloses a biaxial laser processing apparatus that distributes laser beams emitted from a laser light source to two different paths and makes them enter a workpiece. The object to be processed is, for example, a printed circuit board, and a laser beam is incident on a processing point to perform drilling.

  In the laser processing apparatus disclosed in Patent Document 1, the optical system is adjusted so that the powers of the laser beams incident on the processing object through the two paths are equal. For example, the reflectivity of a reflecting mirror arranged in one optical system of two paths is adjusted, and the powers of laser beams passing through both paths are made uniform. By aligning the power in this way, the quality of the holes formed by the laser beam that has passed through each of the two paths can be made uniform.

Japanese Patent Laid-Open No. 2003-212278

  In the conventional laser processing apparatus, it is necessary to adjust the optical system in order to align the powers of the laser beams that have passed through the two paths. For example, in order to adjust the reflectance of the reflecting mirror, the reflecting mirror is exchanged. When the reflector is exchanged, the optical axis must be readjusted.

  One object of the present invention is to distribute a laser beam emitted from a laser light source into a plurality of different paths, and to process a workpiece with a laser beam that passes through each path, and a laser that passes through each of the plurality of paths. It is an object of the present invention to provide a laser processing apparatus that does not require adjustment of an optical system for aligning beam power, and a laser processing method using the same.

  According to the first aspect of the present invention, a laser light source that emits a pulse laser beam and a pulse laser beam that is emitted from the laser light source are incident on a workpiece through a first path. A sorter that switches between a state and a second state that is incident through a second path different from the first path, and a first that is incident when the distributor is in the first state Storage means for separately storing the number of pulses and the second number of pulses to be incident when in the second state, and when the distributor is in the first state, The laser beam is incident such that when the pulse laser beam is incident for the first number of pulses and the distributor is set to the second state, the pulse laser beam is incident on the object to be processed for the second number of pulses. Control light source The laser processing apparatus is provided with a that controller.

  According to the second aspect of the present invention, (a) a pulsed laser beam emitted from a pulsed laser light source is incident on an evaluation workpiece through a first path via a distributor, A step of processing a workpiece and determining a first number of pulses necessary for the processing; and (b) a pulse laser emitted from the pulse laser light source and passing through the first path via the distributor. A step of measuring the power of the beam; and (c) measuring the power of the pulse laser beam emitted from the pulse laser light source and passing through the second path different from the first path via the distributor. And (d) based on the first number of pulses, the measured power of the pulsed laser beam through the first path, and the measured power of the pulsed laser beam through the second path. The second A step of determining a second number of pulses necessary for processing by the pulsed laser beam that has passed through the path; and (e) the first path of the pulsed laser beam emitted from the pulsed laser light source via the distributor. Passing through the unprocessed point of the object to be processed through the first number of pulses and processing (f) the pulse laser beam emitted from the pulse laser light source through the distributor Then, the step of causing the second number of pulses to enter the unprocessed processing point of the processing object through the second path, and (g) the steps (e) and (f) There is provided a laser processing method having a step of alternately repeating.

  According to the third aspect of the present invention, (a) a pulsed laser beam emitted from a pulsed laser light source is incident on an evaluation workpiece through a first path via a distributor, A step of processing a workpiece and determining a first number of pulses necessary for the processing; and (b) passing the pulse laser beam emitted from the pulse laser light source to the first path via the distributor. Entering the evaluation workpiece through a different second path, processing the evaluation workpiece, and determining a second number of pulses necessary for the processing, and (c) the pulse laser light source A process of causing the pulse laser beam emitted from the first laser beam to enter the unprocessed processing point of the processing object through the first path via the distributor and the first number of pulses; (D) Get out of the pulse laser light source A step of causing the pulsed laser beam to enter the unprocessed processing point of the object to be processed through the second path via the distributor for the second number of pulses, and (e) There is provided a laser processing method comprising the steps of alternately repeating the steps (c) and (d).

  In the laser processing apparatus according to the first aspect, the pulse laser beam that has passed through the first path is incident on the object to be processed by the first number of pulses, and the pulse laser beam that has passed through the second path is the second pulse. The number of pulses is incident on the workpiece. The first pulse number and the second pulse number are stored separately in the storage means. For example, consider the case of drilling a workpiece with a pulsed laser beam. If the laser processing apparatus according to the first aspect is used, even if the powers of the pulse laser beams incident on the workpiece after passing through the first and second paths are different from each other, the first and second pulse numbers By appropriately setting each, it is possible to reduce the difference in the quality of holes formed by the pulse laser beam that has passed through each of the two paths.

  In the laser processing methods according to the second and third aspects, the first pulse number is determined by processing the evaluation object. Thereby, the first pulse number can be appropriately determined. In the method of the second aspect, the second number of pulses is based on the first number of pulses, the power of the pulse laser beam that has passed through the first path, and the power of the pulse laser beam that has passed through the second path. decide. For example, if the power of the pulse laser beam passing through the second path is greater than the power of the pulse laser beam passing through the first path, the second pulse number is set to a value smaller than the first pulse number. Can do. In the method according to the third aspect, the second number of pulses is determined by processing the evaluation object.

  For example, consider the case of drilling a workpiece with a pulsed laser beam. If the laser processing method according to the second and third aspects is used, the difference between the quality of the holes formed by the pulse laser beam that has passed through each of the first and second paths is suppressed. The number of pulses of 2 can be determined.

  FIG. 1 is a schematic view of a laser processing apparatus according to an embodiment of the present invention. The laser light source 1 emits a pulse laser beam L. The laser light source 1 is a laser oscillator that emits a laser beam having a wavelength in the ultraviolet region, and includes, for example, an Nd: YAG laser oscillator and a nonlinear optical element. The pulse laser beam L is, for example, the third harmonic (wavelength 355 nm) of an Nd: YAG laser. A trigger signal for emitting the pulsed laser beam L is sent from the control device 20 to the laser light source 1.

  A pulsed laser beam L is incident on the distributor 2. The distributor 2 includes a half-wave plate 2a, an electro-optic element 2b exhibiting a Pockels effect, and a polarizing plate 2c. The half-wave plate 2a causes the pulsed laser beam L emitted from the laser light source 1 to be linearly polarized so as to be a P wave with respect to the polarizing plate 2c and enter the electro-optic element 2b. The polarizing plate 2c transmits the P wave and reflects the S wave.

The electro-optical element 2 b rotates the polarization plane of the pulse laser beam based on the control signal sig ₀ sent from the control device 20. When the electro-optic element 2b is not applied with a voltage, the incident P wave is emitted as it is. When the electro-optic element 2b is in a voltage application state, the electro-optic element 2b turns the polarization plane of the P wave by 90 degrees and turns the pulse laser beam emitted from the electro-optic element 2b into an S wave for the polarizing plate 2c. To do.

A path through which the pulse laser beam L1 transmitted through the polarizing plate 2c propagates is referred to as a first path, and a path through which the pulse laser beam L2 reflected by the polarizing plate 2c propagates is referred to as a second path. Based on the control signal sig ₀ , the distributor 2 switches between a state in which the pulse laser beam passes through the first path and a state in which the pulse laser beam passes through the second path. The power of the pulse laser beam L1 emitted from the distributor 2 when the pulse laser beam passes through the first path and the power of the pulse laser beam L1 emitted from the distributor 2 when the pulse laser beam passes through the second path. The power of the pulse laser beam L2 is substantially equal.

  The pulse laser beam L 1 emitted from the distributor 2 is reflected by the folding mirror 3, passes through the galvano scanner 4, is converged by the fθ lens 5, and then enters the workpiece 8. The pulse laser beam L2 emitted from the distributor 2 passes through the galvano scanner 6 and is converged by the fθ lens 7 and then enters the workpiece 8. The processing object 8 is, for example, a printed board.

  The surface of the workpiece 8 is divided into a plurality of unit machining areas. In each unit processing region, a plurality of processing points where a laser beam is incident to form a hole are defined. A plurality of pulses (for example, about 50 to 60 pulses) of a pulsed laser beam are made incident on each workpiece point to perform drilling.

  The pulsed laser beam L1 passing through the first path is incident on a certain unit processing region on the processing target 8. The galvano scanner 4 oscillates the propagation direction of the pulse laser beam L1 in a two-dimensional direction so that the laser beam is incident on each processing point in the unit processing region. The number of pulses required to make a hole to be machined with the pulse laser beam L1 (referred to as the first pulse number N1) is stored in the storage means 20a included in the control device 20.

The pulsed laser beam L2 passing through the second path is incident on another unit processing region on the processing target 8. The galvano scanner 6 oscillates the propagation direction of the pulse laser beam L2 in a two-dimensional direction so that the laser beam is incident on each processing point in the unit processing region. The number of pulses necessary for drilling one workpiece point with the pulse laser beam L2 (referred to as the second pulse number N2) is stored in the storage means 20a included in the control device 20. The galvano scanners 4 and 6 are driven by drive signals sig ₁ and sig ₂ transmitted from the control device 20, respectively.

  The stage 9 holds the workpiece 8. The stage 9 moves the workpiece 8 in a two-dimensional direction parallel to the surface thereof, and arranges a desired unit processing region at a position where the laser beam can be irradiated. The control device 20 controls the stage 9.

  A power meter 10 that measures the power of the laser beam is installed on the stage 9. By moving the power meter 10 below the fθ lens 5 by the stage 9 and causing the pulse laser beam L1 to enter the power meter 10, the power of the pulse laser beam L1 passing through the first path is measured. By moving the power meter 10 under the fθ lens 7 by the stage 9 and causing the pulse laser beam L2 to enter the power meter 10, the power of the pulse laser beam L2 passing through the second path is measured. Data indicating the power measurement value is sent to the control device 20.

  The optical path length of the first path from the distributor 2 to the surface of the workpiece 8 and the optical path length of the second path from the distributor 2 to the surface of the workpiece 8 are not necessarily equal to each other. The optical system on the first path is different from the optical system on the second path. For example, due to these reasons, even if the powers of the pulse laser beams L1 and L2 emitted from the distributor 2 are equal to each other, the powers of both pulse laser beams are not necessarily equal on the surface of the workpiece 8. .

In the current technology, the output of the pulse laser beam in the ultraviolet region is lower than, for example, the output of the pulse laser beam in the infrared region emitted from the CO ₂ laser oscillator. For example, when punching a printed circuit board, the number of pulses incident per hole is several pulses (for example, 1 to 2 pulses) in the infrared pulse laser beam emitted from the CO ₂ laser oscillator, The pulse laser beam has several tens of pulses (for example, 50 to 60 pulses). Let us consider a case where the pulse laser beam that has passed through the first path and the pulse laser beam that has passed through the second path are incident on the workpiece by an equal number of pulses. When a pulse laser beam in the ultraviolet region is used, even if the energy difference per pulse of the pulse laser beam incident on the workpiece through the first and second paths is very small, the number of incident pulses is small. Since there are many, the difference of the energy which injects through both path | routes will each enlarge.

  When processing is performed with the pulsed laser beam L1 passing through the first path, the optical device through which the pulsed laser beam L1 finally passes before entering the processing point is the fθ lens 5. The power meter 10 measures the power of the pulsed laser beam L1 that has passed through the fθ lens 5. For this reason, the power of the pulse laser beam L1 to be measured is substantially equal to the power of the pulse laser beam L1 incident on the processing point. When processing is performed with the pulsed laser beam L2 passing through the second path, the pulsed laser beam L2 finally passes through the fθ lens 7. Since the power meter 10 measures the power of the pulsed laser beam L2 that has passed through the fθ lens 7, the measured value is substantially equal to the power of the pulsed laser beam L2 incident on the processing point.

  Next, a laser processing method using the laser processing apparatus according to the embodiment will be described. First, a method of determining the first pulse number N1 and the second pulse number N2 will be described with reference to FIG.

  A processing object for evaluation is placed on the stage 9 in FIG. In step ST1, the pulsed laser beam L1 that has passed through the first path is made incident on the workpiece to be evaluated, and drilling is performed. By processing a workpiece to be evaluated, a first pulse number N1 that is optimal for drilling is determined. The first pulse number N1 is stored in the storage unit 20a of the control device 20. In step ST2, the provisional value of the second pulse number N2 is determined to be equal to the first pulse number N1 and stored in the storage unit 20a of the control device 20.

  In step ST3, the power meter 10 is moved below the fθ lens 5 to measure the power of the pulse laser beam L1. This measured value is set to P1. In step ST4, the power meter 10 is moved below the fθ lens 7 and the power of the pulse laser beam L2 is measured. This measured value is set to P2. In step ST5, a ratio C (= P2 / P1) of the power P2 to the power P1 is calculated.

  In step ST6, it is selected whether to correct the second pulse number N2 from the provisional value. If not corrected, the second pulse number is determined to be equal to the first pulse number. In this case, further, the optical system is adjusted so that the power of the pulse laser beam passing through each of the first and second paths becomes equal, and processing by the conventional method is performed. When correcting the second pulse number N2, the process proceeds to step ST7.

  In step ST7, it is determined whether or not the ratio C of the power P2 to the power P1 is within an allowable range. For example, it is determined whether or not the ratio C is between 0.9 and 1.1 (that is, whether or not the difference between the powers P2 and P1 is within ± 10% with respect to the power P1). If it is not within the allowable range, that is, if the difference between the power P1 and the power P2 exceeds the allowable value, there is a high possibility that some abnormality has occurred in the optical system. In this case, the laser processing apparatus is inspected. When the ratio C of the power P2 to the power P1 is within the allowable range, the process proceeds to step ST8.

  In step ST8, the second pulse number N2 is determined based on a value N1 / C obtained by dividing the first pulse number N1 by the ratio C. When N1 / C is an integer, the second pulse number N2 is determined to be equal to N1 / C, and when N1 / C is a non-integer, the second pulse number N2 is the first fractional number of N1 / C. It is set equal to the integer value rounded off. The second pulse number N2 determined in this way is stored in the storage means 20a of the control device 20, and the second pulse number N2 is updated from the provisional value. As described above, the first and second pulse numbers are determined by the process described with reference to FIG.

Next, a method for controlling the sorting optical device 2 and the galvano scanners 4 and 6 will be described with reference to FIG. FIG. 3 shows a timing chart of the control signal sig ₀ , the drive signals sig ₁ and sig ₂ , and the pulsed laser beams L1 and L2. Based on the control signal sig ₀ , the pulse laser beam L1 propagating through the first path is emitted from the distributor 2 during the first period T1 in which the electro-optic element 2b of the distributor 2 is in the no-voltage application state. . The pulse laser beam L1 enters the workpiece 8 through the galvano scanner 4.

During the first period T1, the control device 20 transmits a drive signal sig ₂ to the galvano scanner 6 on which the pulse laser beam is not incident, and the galvano scanner 6 transmits the pulse laser beam to the workpiece 8. Control is performed so that the light is focused on the desired processing point above.

In the second period T2 after the first period T1, the electro-optic element 2b is in a voltage application state by the control signal sig ₀ , and the pulse laser beam L2 propagating through the second path is emitted from the distributor 2. To do. During the previous first period T1, the galvano scanner 6 is driven to adjust the point where the pulsed laser beam should be focused. For this reason, the pulsed laser beam L2 enters the desired workpiece point on the workpiece 8 through the galvano scanner 6.

Further, during the second period T2, the control device 20 transmits a drive signal sig ₁ to the galvano scanner 4 on which the pulse laser beam is not incident, and the galvano scanner 4 processes the pulse laser beam. Control is performed so that the light is focused on a desired processing point on the object 8.

  By alternately repeating the first period T1 and the second period T2, it is possible to make holes at a plurality of desired points to be processed on the workpiece 8. In each of the repeated first periods T1, the pulsed laser beam L2 is incident on the processing point by the first number of pulses N1, and in each of the repeated second periods T2, the pulsed laser beam L2 However, the laser light source 1 is controlled so as to be incident on the processing point by the second pulse number N2.

  As described above, in the laser processing apparatus according to the embodiment, when drilling with the pulse laser beam L1 passing through the first path, the laser beam is applied to the processing object by the first number of pulses per processing point. When making L1 incident and making a hole with the pulsed laser beam L2 that has passed through the second path, the pulsed laser beam L2 is incident on the workpiece by the second number of pulses per workpiece. Even if the powers of the pulsed laser beams L1 and L2 incident on the workpiece after passing through the first and second paths are different from each other, the number of pulses required for the machining can be set separately, so that the pulse The difference in the quality of the holes formed by the laser beams L1 and L2 can be reduced.

  The first number of pulses required for processing with the pulsed laser beam L1 is determined by processing a workpiece to be evaluated. Thereby, an appropriate first number of pulses can be obtained. The second number of pulses necessary for processing with the pulse laser beam L2 is obtained, for example, as described in step ST8 of FIG. When the power of the pulse laser beam L2 passing through the second path is larger than the power of the pulse laser beam L1 passing through the first path, the second pulse number is made smaller than the first pulse number, When the power of the pulse laser beam L2 passing through the second path is smaller than the power of the pulse laser beam L1 passing through the first path, the second pulse number is made larger than the first pulse number.

  By determining the second number of pulses in this way, the pulse laser beam L2 formed through the second path is formed as compared with the case where the second number of pulses is fixed to a value equal to the first number of pulses. The quality of the hole formed can be made close to the quality of the hole formed by the pulsed laser beam L1 passing through the first path.

  In addition, the first and second pulse numbers are obtained by processing the object to be evaluated with the pulse laser beam L1 passing through the first path and the pulse laser beam L2 passing through the second path, respectively. Each can be decided.

  Conventionally, the optical systems on the first and second paths are adjusted so that the powers of the pulse laser beams incident on the workpiece 8 through the first and second paths are equal to each other. Quality was aligned. It is assumed that the power of the pulse laser beam passing through one path is higher than the power of the pulse laser beam passing through the other path before the power adjustment. In order to equalize the power of the pulsed laser beam through both paths, it is necessary to arrange an optical device that attenuates the power of the laser beam in the path having the higher measurement power. If an attempt is made to equalize the powers of the pulsed laser beams that have passed through both paths, an unnecessary power loss occurs in this way.

  In the laser processing method using the laser processing apparatus of the embodiment, it is not necessary to make the powers of the pulse laser beams that have passed through the first and second paths equal to each other. For this reason, the above unnecessary power loss does not occur.

  In a laser processing apparatus using only one galvano scanner, processing cannot be performed while the galvano scanner is driven to move the incident position of the pulse laser beam. In the laser processing apparatus of the embodiment having two galvano scanners, processing can be performed with the pulse laser beam that has passed through the other galvano scanner during the period in which the incident position of the pulse laser beam is moved by one galvano scanner. . For this reason, it can process efficiently in time.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

It is the schematic of the laser processing apparatus by the Example of this invention. It is a flowchart for demonstrating the method of determining the 1st and 2nd pulse number. It is a timing chart for demonstrating the control method of a sorter and a galvano scanner.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser light source 2 Sorting device 2a Half-wave plate 2b Electro-optical element 2c Polarizing plate 3 Folding mirror 4, 6 Galvano scanner 5, 7 f (theta) lens 8 Work object 9 Stage 10 Power meter 20 Control apparatus 20a Memory | storage means L, L1, L2 Pulse laser beam sig ₀ control signal sig ₁ , sig ₂ drive signal

Claims (8)

A laser light source for emitting a pulsed laser beam;
A first state in which the pulse laser beam emitted from the laser light source is incident on the workpiece through the first path, and a second state in which the pulse laser beam is incident through a second path different from the first path. A sorter for switching between the two states;
Storage means for separately storing a first pulse number that is incident when the distributor is in the first state and a second pulse number that is incident when the distributor is in the second state; When the distributor is in the first state, a pulse laser beam is incident on the object to be processed by the first number of pulses, and when the distributor is in the second state, the object to be processed is And a control device for controlling the laser light source so that a pulse laser beam is incident on the second pulse number. further,
A first beam scanner disposed on the first path and moving an incident position of the pulsed laser beam within a certain region on the workpiece;
2. The laser processing apparatus according to claim 1, further comprising: a second beam scanner which is disposed on the second path and moves the incident position of the pulse laser beam within a certain region on the processing target. (A) A pulse laser beam emitted from a pulse laser light source is incident on an evaluation processing object through a first path via a distributor, and the evaluation processing object is processed, which is necessary for processing. Determining a first pulse number;
(B) measuring the power of the pulsed laser beam emitted from the pulsed laser light source and passed through the first path via the distributor;
(C) measuring the power of the pulse laser beam emitted from the pulse laser light source and passing through the second path different from the first path via the distributor;
(D) based on the first pulse number, the measured power of the pulsed laser beam through the first path, and the measured power of the pulsed laser beam through the second path; Determining a second number of pulses required for processing with a pulsed laser beam through two paths;
(E) The pulse laser beam emitted from the pulse laser light source is incident on the unprocessed point of the object to be processed through the first path via the distributor for the first number of pulses. Process to process,
(F) The pulse laser beam emitted from the pulse laser light source is incident on the unprocessed point of the object to be processed through the second path via the distributor for the second number of pulses. Process to process,
(G) A laser processing method including a step of alternately repeating the steps (e) and (f). The first pulse number is N1, the measured power of the pulse laser beam passing through the first path is P1, and the measured power of the pulse laser beam passing through the second path is P2. The laser processing method according to claim 3, wherein when the second pulse number is N2, the second pulse number N2 is obtained based on N1 / (P2 / P1) in the step (d). A first beam scanner is disposed on the first path, a second beam scanner is disposed on the second path, and the step (e) includes the first beam scanner. During the period in which the pulse laser beam is incident on the workpiece through the scanner, the position on the workpiece to which the pulse laser beam passing through the second beam scanner is incident is moved. Controlling the second beam scanner, wherein the step (f) is performed during the period in which the pulsed laser beam is incident on the workpiece through the second beam scanner. 5. The laser processing method according to claim 3, further comprising the step of controlling the first beam scanner so that the position on the workpiece on which the pulsed laser beam passes through the scanner moves. In the step (b), the power of the pulse laser beam emitted from the optical device through which the pulse laser beam incident on the workpiece through the first path finally passes is measured, and in the step (c), The laser processing method according to any one of claims 3 to 5, wherein the power of the pulse laser beam emitted from the optical device through which the pulse laser beam incident on the workpiece through the second path finally passes is measured. (A) A pulse laser beam emitted from a pulse laser light source is incident on an evaluation processing object through a first path via a distributor, and the evaluation processing object is processed, which is necessary for processing. Determining a first pulse number;
(B) A pulsed laser beam emitted from the pulsed laser light source is incident on the evaluation object via a second path different from the first path via the distributor, and the evaluation processing Processing the object and determining a second number of pulses required for processing;
(C) The pulse laser beam emitted from the pulse laser light source is incident on the unprocessed point of the object to be processed through the first path via the distributor for the first number of pulses. Process to process,
(D) The pulse laser beam emitted from the pulse laser light source is incident on the unprocessed point of the object to be processed through the second path via the distributor for the second number of pulses. Process to process,
(E) A laser processing method including a step of alternately repeating the steps (c) and (d). A first beam scanner is disposed on the first path, a second beam scanner is disposed on the second path, and the step (c) includes the first beam. During the period in which the pulse laser beam is incident on the workpiece through the scanner, the position on the workpiece to which the pulse laser beam passing through the second beam scanner is incident is moved. Controlling the second beam scanner, wherein the step (d) is performed during the period in which the pulsed laser beam is incident on the workpiece through the second beam scanner. The laser processing method according to claim 7, further comprising the step of controlling the first beam scanner so that a position on the workpiece on which the pulsed laser beam passes through the scanner moves.

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