JP2019130564A - Laser control device and laser processing method - Google Patents

Abstract

To provide a laser control device that can perform feedback control so that pulse energy can be kept at a target value even when performing cycle processing.SOLUTION: The laser control device is assembled to a laser processing device that performs laser processing by repeating for a plural number of cycles a procedure, as one cycle, in which a laser oscillator is made to output pulse laser beams and then one shot of the pulse laser beams is made incident on each of a plurality of points to be processed of an object to be processed, in turns. The laser control device controls the laser oscillator so that an energy measured value, a measured value of pulse energy of the pulse laser beams is kept at an energy target value, a target value of the pulse energy set for every cycle.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a laser control device and a laser processing method.

  A laser processing technique is known in which a laser beam is incident on a substrate having a metal film disposed on the top and bottom surfaces of a resin layer to make holes in the metal film and the resin layer on the top surface (Patent Document 1). In the laser processing disclosed in Patent Document 1, a portion having a relatively high light intensity is cut out from one laser pulse output from the laser oscillator, and a metal film on the upper surface is drilled, and after attenuation starts. A portion with low light intensity is cut out and drilled in the resin layer. In this way, the processing for processing the next processing point after the drilling of one processing point is completed is called burst processing.

  For burst processing, a process in which a pulse laser beam is incident on a plurality of processing points of a processing target in order one shot at a time is used as one cycle, and processing is repeated for a plurality of common processing points. Is called cycle machining. In cycle machining, the time interval between a plurality of laser pulses incident on one workpiece point becomes long, and therefore, there is an advantage that it is difficult to be affected by heat storage due to incidence of laser pulses.

  In the cycle processing, the metal film is perforated in the first cycle, and the resin film is perforated in the second and subsequent cycles. The total number of cycles is determined by the required specification of processing quality, the thickness of the resin film, and the like.

JP 2017-47471 A

  In processing using a pulse laser beam, the optimum pulse energy for processing is selected. The pulse energy for making holes in the metal film is larger than the pulse energy for making holes in the resin film. When performing cycle machining, the pulse energy in the first cycle is larger than the pulse energy in the second and subsequent cycles. Generally, the pulse energy is adjusted by changing the pulse width.

  During laser processing, feedback control is performed on the laser oscillator so that the pulse energy is maintained at the target value. However, when performing cycle machining, the target value of pulse energy changes for each cycle. For this reason, conventionally, feedback control has not been performed during cycle machining.

  An object of the present invention is to provide a laser control apparatus capable of performing feedback control such that pulse energy is maintained at a target value even when performing cycle machining. Another object of the present invention is to provide a laser machining method capable of performing cycle machining while performing feedback control such that pulse energy is maintained at a target value.

According to one aspect of the invention,
A procedure in which a pulse laser beam is output from a laser oscillator and a pulse laser beam is sequentially incident on a plurality of processing points of a processing target one shot at a time is regarded as one cycle, and a plurality of processing points are applied to a plurality of processing points. A laser control device incorporated in a laser processing apparatus that performs laser processing by repeating a cycle,
Provided is a laser control device that controls the laser oscillator so that an energy measurement value that is a pulse energy measurement value of a pulsed laser beam is maintained at an energy target value that is a pulse energy target value set for each cycle. Is done.

According to another aspect of the invention,
This is a method of performing laser processing by repeating a plurality of cycles on a plurality of the processing points, with a procedure in which a pulsed laser beam is sequentially incident on a plurality of processing points of a processing target one shot at a time. And
When performing a plurality of cycles while performing feedback control so that pulse energy is maintained at an energy target value that is a target value of pulse energy for a laser oscillator that outputs a pulsed laser beam, at least two different There is provided a laser processing method using different values as the energy target values in a cycle.

  Since the target value of pulse energy is set for each cycle, feedback control can be performed even when the target value of pulse energy is different for each cycle.

FIG. 1 is a schematic diagram of a laser processing apparatus incorporating a laser control apparatus according to an embodiment. 2A and 2B are a plan view and a cross-sectional view, respectively, of the workpiece, and the drawings on the left side of FIGS. 2C to 2E show the processing order of the processing points in the first to third cycles in one block, respectively. The right-side drawings are cross-sectional views of one workpiece point when the first to third cycles are completed. FIG. 3 is a block diagram of the laser control apparatus according to this embodiment. FIG. 4 is a chart showing an example of the oscillation condition parameter. FIG. 5 is a graph showing the relationship between the deviation (energy deviation) from the energy target value Er to the energy measurement value Em and the increase / decrease amount of the voltage command value Vc. FIG. 6 is a flowchart of processing performed by the laser control apparatus. FIG. 7 shows an example of temporal changes in the oscillation command signal S0, the cycle designation signal S3, the energy target value Er, the energy measurement value Em, and the feedback gain G when machining with the laser machining apparatus equipped with the laser control apparatus according to the embodiment. It is a graph which shows. FIG. 8 shows an example of the time change of the oscillation command signal S0, the cycle designation signal S3, the energy target value Er, the energy measurement value Em, and the feedback gain G when machining with a laser machining apparatus equipped with a laser control apparatus according to a modification. It is a graph which shows.

With reference to FIGS. 1-7, the laser control apparatus and laser processing method by an Example are demonstrated.
FIG. 1 is a schematic diagram of a laser processing apparatus incorporating a laser control apparatus according to an embodiment. The laser oscillator 10 outputs a pulsed laser beam under the control of the laser control device 30. As the laser oscillator 10, a laser oscillator that outputs a pulse laser beam, for example, a gas laser oscillator such as a carbon dioxide laser oscillator can be used. The laser oscillator 10 includes a laser medium gas, a discharge electrode for excitation, a power source for supplying high frequency power to the discharge electrode, and the like.

  The pulse laser beam output from the laser oscillator 10 passes through the optical system 11 including a beam expander and the like, is reflected by the bending mirror 12, passes through the aperture 13, and enters the branching optical system 15. The branching optical system 15 branches the incident pulse laser beam into two paths. As the branching optical system 15, a half mirror, a polarizing beam splitter, an acoustooptic device (AOM), or the like can be used.

  The pulsed laser beam branched by the branching optical system 15 and propagating through one path enters the workpiece 20A via the beam scanner 16A and the lens 17A. The pulsed laser beam propagating through the other path enters the workpiece 20B via the beam scanner 16B and the lens 17B. The beam scanners 16A and 16B include, for example, a pair of galvanometer mirrors, and have a function of scanning a pulse laser beam in a two-dimensional direction. The lenses 17A and 17B focus the pulse laser beam on the surfaces of the workpieces 20A and 20B, respectively. Note that the aperture 13 may be configured to form an image on the surfaces of the workpieces 20A and 20B.

  The workpieces 20 </ b> A and 20 </ b> B are, for example, printed wiring boards and are held on the holding surface of the stage 18. Drilling is performed by making a pulse laser beam incident on the printed wiring board. The holding surface of the stage 18 is horizontal, for example. The stage 18 can move the workpieces 20A and 20B in two directions in the horizontal plane. As the stage 18, for example, an XY stage can be used.

  Part of the pulse laser beam incident on the bending mirror 12 passes through the bending mirror 12 and enters the photodetector 19. The photodetector 19 outputs an electrical signal (detection signal S1) corresponding to the light intensity of the incident pulse laser beam. As the photodetector 19, an infrared sensor having a response speed capable of following a change in the laser pulse waveform, for example, an MCT sensor or the like can be used. The detection signal S <b> 1 is input to the laser control device 30.

  The host controller 40 controls the beam scanners 16A and 16B and the stage 18. Furthermore, the host controller 40 transmits an oscillation command signal S0 that instructs the laser controller 30 to start and stop the output of the laser pulse. The laser control device 30 starts excitation of the laser oscillator 10 when the start of output of laser pulses is commanded from the host control device 40, and stops excitation of the laser oscillator 10 when commanded to stop output.

  FIG. 2A is a plan view of the workpiece 20. The surface of the workpiece 20 is divided into a plurality of blocks 21, and a plurality of workpiece points 22 are defined in each block 21. Each of the blocks 21 is smaller than a range in which the pulse laser beam can be scanned by the beam scanners 16A and 16B. For this reason, the processing in one block 21 can be performed by driving the beam scanners 16 </ b> A and 16 </ b> B without moving the workpiece 20 on the stage 18.

  FIG. 2B is a cross-sectional view of the workpiece 20. Metal films 24 and 25 are attached to the upper and lower surfaces of the resin layer 23, respectively. For the metal films 24 and 25, for example, copper foil is used. In the present embodiment, a pulse laser beam is made incident on a workpiece point 22 (FIG. 2A) of the workpiece 20 to make holes in the upper metal film 24 and the resin layer 23, and the lower metal on the bottom of the hole. Processing to expose the film 25 is performed.

  In this embodiment, cycle machining is applied. A cycle in which the pulsed laser beam is output from the laser oscillator 10 (FIG. 1) and the pulsed laser beam is sequentially incident on all the processing points 22 (FIG. 2A) in one block 21 one shot at a time. To do. By repeating a plurality of cycles for a plurality of processing points 22, a plurality of laser pulses are incident on all the processing points 22 in one block 21 to perform drilling. A plurality of processing points 22 on which the pulse laser beam is incident in each cycle are common. That is, the plurality of processing points 22 to which the pulse laser beam is incident in each cycle after the second cycle are the same as the plurality of processing points 22 to which the pulse laser beam is incident in the first cycle. Note that the order of the workpiece points 22 on which the pulse laser beam is incident is not necessarily the same between cycles.

  Next, with reference to FIG. 2C to FIG. 2E, a procedure for drilling the workpiece 20 will be described. The left diagram of FIG. 2C is a plan view showing the machining order of the machining points 22 in the first cycle in one block 21, and the right diagram shows one machining point when the first cycle is completed. FIG. 2D and 2E are similar plan views and cross-sectional views in the second and third cycles, respectively.

  2C to 2E, a plurality of processing points 22 are defined on the surface of the block 21. In any of the first cycle, the second cycle, and the third cycle, the machining order of the plurality of workpiece points 22 is the same.

  As shown in the diagram on the right side of FIG. 2C, the laser pulse 26 enters the processing point 22 in the first cycle, whereby a hole 29 is formed. The width of the figure representing the laser pulse 26 corresponds to the beam size, and the area corresponds to the pulse energy. The hole 29 formed in the first cycle passes through the metal film 24 on the upper surface and reaches the middle of the resin layer 23 in the thickness direction, but does not reach the metal film 25 on the lower surface.

  As shown in the diagram on the right side of FIG. 2D, the laser pulse 27 is incident on the workpiece point 22 in the second cycle, and the hole 29 is deepened. As shown in the diagram on the right side of FIG. 2E, the laser pulse 28 enters the processing point 22 in the third cycle, and the hole 29 reaches the metal film 25 on the lower surface. Laser processing is completed in three cycles. The pulse energy of the laser pulse 27 in the second cycle and the laser pulse 28 in the third cycle is smaller than the pulse energy of the laser pulse 26 in the first cycle.

  FIG. 3 is a block diagram of the laser control device 30 according to this embodiment. The laser control device 30 includes a drive signal transmission unit 31, a feedback control unit 32, a parameter setting unit 33, a cycle designation information setting unit 34, and a pulse energy calculation unit 35. The functions of these units are realized by a computer executing an application program, for example.

  The drive signal transmission unit 31 receives an oscillation command signal S0 that commands the start and stop of oscillation from the host controller 40, and transmits the drive signal S2 to the laser oscillator 10 based on the oscillation command signal S0. For example, the rising and falling edges of the oscillation command signal S0 mean oscillation start and oscillation stop commands, respectively. The drive signal transmission unit 31 starts transmission of the drive signal S2 to the laser oscillator 10 when receiving a command to start oscillation, and stops transmission of the drive signal S2 to the laser oscillator 10 when receiving a command to stop oscillation. . The laser oscillator 10 applies a high-frequency discharge voltage to the discharge electrode while receiving the drive signal S2 from the drive signal transmitter 31. A laser pulse is output from the laser oscillator 10 by applying a discharge voltage to the discharge electrode.

  The parameter setting unit 33 receives the oscillation condition parameter setting signal S4 from the host controller 40 and stores the oscillation condition parameter.

  FIG. 4 is a chart showing an example of the oscillation condition parameter. The oscillation condition parameters include an energy target value Er, a voltage initial value Vo, and a feedback gain G. These oscillation condition parameters are set for each cycle. For example, information designating the nth cycle is represented by cycle number n. The oscillation condition parameter is used in feedback control executed by the feedback control unit 32.

  The cycle designation information setting unit 34 shown in FIG. 3 acquires a cycle designation signal S3 that designates one cycle from the first cycle to the third cycle from the host controller 40, and is designated by the cycle designation signal S3. Cycle designation information Cy, for example, a cycle number is stored. The host controller 40 transmits a cycle designation signal S3 for designating the currently executing cycle to the cycle designation information setting unit 34.

  The pulse energy calculation unit 35 receives the detection signal S1 from the photodetector 19, and calculates the pulse energy based on the detection signal S1. For example, the pulse energy is calculated by integrating the pulse waveform of the detection signal S1. Furthermore, the energy measurement value Em is obtained by averaging the calculated value of the pulse energy over a plurality of laser pulses.

  The feedback control unit 32 performs feedback control on the laser oscillator 10 so that the energy measurement value Em obtained by the pulse energy calculation unit 35 is maintained at the energy target value Er stored in the parameter setting unit 33. Do. For example, the voltage command value Vc applied to the laser oscillator 10 is increased or decreased based on the deviation from the energy target value Er to the energy measurement value Em and the feedback gain G. The laser oscillator 10 performs pulsed laser oscillation by applying a voltage commanded by the voltage command value Vc to the discharge electrode.

  When performing this feedback control, the feedback control unit 32 uses the energy target value Er and the feedback gain G corresponding to the currently executing cycle. The currently executing cycle can be specified based on the cycle designation information Cy stored in the cycle designation information setting unit 34.

  Next, feedback control performed by the feedback control unit 32 will be described with reference to FIG.

  FIG. 5 is a graph showing the relationship between the deviation (energy deviation) from the energy target value Er to the energy measurement value Em and the increase / decrease amount of the voltage command value Vc. The relationship between the energy deviation and the increase / decrease amount of the voltage command value Vc is defined for each feedback gain G. Regardless of the feedback gain G, if the deviation is zero, the increase / decrease amount of the voltage command value Vc is zero. When the energy measurement value Em is equal to or greater than the energy target value Er (when the energy deviation is positive), the voltage command value Vc is lowered as the energy deviation increases. When the energy measurement value Em is equal to or less than the energy target value Er (when the energy deviation is negative), the voltage command value Vc is increased as the absolute value of the deviation increases. The feedback gain G is the ratio of the increase / decrease amount of the voltage command value Vc to the energy deviation (slope of the graph in FIG. 5). As the feedback gain G increases, the slope of the graph increases in the negative direction.

  The feedback control unit 32 determines the increase / decrease amount of the voltage command value Vc based on the relationship between the energy deviation and the increase / decrease amount of the voltage command value Vc shown in FIG. The feedback control to the voltage command value Vc is executed every predetermined number of shots (for example, every 1000 shots), for example, during a period when one block 21 (FIG. 2A) is processed.

  FIG. 6 is a flowchart of laser processing using a laser processing apparatus equipped with the laser control device 30. First, the laser control device 30 receives the oscillation condition parameter setting signal S4 (FIG. 3) from the host control device 40, and stores the oscillation condition parameter (FIG. 4) (step ST0). Further, the laser control device 30 receives the cycle designation signal S3 from the host control device 40. Initially, cycle number 1 is designated by the cycle designation signal S3, and the cycle number is initialized (step ST1).

  The feedback control unit 32 of the laser control device 30 acquires the cycle designation information Cy from the cycle designation information setting unit 34. Furthermore, the energy target value Er and the feedback gain G (FIG. 4) of the cycle designated by the cycle designation information Cy are acquired from the parameter setting unit 33 (step ST2).

  The laser control device 30 updates the feedback gain G based on the measurement result of the laser energy during execution of the same cycle of the block 21 (FIG. 2A) processed immediately before (step ST3). When the block 21 to be processed is the first block, the value acquired from the parameter setting unit 33 is used as the feedback gain G. For example, when the energy measurement value Em in the same cycle of the block 21 processed immediately before is too large with respect to the energy target value, the feedback gain G may be updated in the direction of decreasing the feedback gain G. As described above, the feedback gain G may be increased or decreased based on the difference between the energy measurement value Em and the energy target value.

  One cycle of machining is executed while periodically updating the voltage command value Vc (every predetermined number of shots) so that the energy measurement value Em is maintained at the energy target value Er (step ST4). As the initial value of the voltage command value Vc, the voltage initial value Vo (FIG. 4) stored in the parameter setting unit 33 is used.

  The cycle number is updated until processing of one block 21 (FIG. 2A) is completed (step ST6), and the processing from step ST2 to step ST4 is repeated (step ST5). The host controller 40 determines whether or not one block has been processed. The cycle number is updated by the host controller 40 transmitting a cycle designation signal S3 to the cycle designation information setting unit 34 of the laser controller 30.

  When the processing of one block 21 is finished, it is determined whether or not the processing of all the blocks 21 is finished (sy step ST7). This determination is performed by the host control device 40. When the unprocessed block 21 remains, the host controller 40 moves the block 21 to be processed next to the laser scanable range (step ST8) and initializes the cycle number (step ST9). Thereafter, the processing from step ST2 to step ST5 is repeated. When the processing of all the blocks 21 is finished, the laser processing for the workpiece 20 is finished.

  FIG. 7 is a graph showing an example of temporal changes in the oscillation command signal S0, the cycle designation signal S3, the energy target value Er, the energy measurement value Em, and the feedback gain G. Processing of one block 21 (FIG. 2A) is performed during a period from time t0 to t5, and processing of the next block 21 is performed during a period from time t6 to t11. During the period from time t0 to t1, and from time t6 to t7, the first cycle machining is performed, and during the period from time t2 to t3 and from time t8 to t9, the second cycle machining is performed, The third cycle of machining is performed during the period from time t4 to t5 and from time t10 to t11.

  In the period for processing the first cycle, a cycle designation signal S3 for designating the first cycle is transmitted from the host controller 40 to the laser controller 30. In the period for processing the second cycle, a cycle designation signal S3 for designating the second cycle is transmitted from the host controller 40 to the laser controller 30. In the period for processing the third cycle, a cycle designation signal S3 for designating the third cycle is transmitted from the host controller 40 to the laser controller 30.

  During the machining period of the first cycle, the energy target value Er and the feedback gain G are set to the energy target value Er (1) and the feedback gain G (1) of the first cycle, respectively. During the machining period of the second cycle, the energy target value Er and the feedback gain G are set to the energy target value Er (2) and the feedback gain G (2) of the second cycle, respectively. During the processing period of the third cycle, the energy target value Er and the feedback gain G are set to the energy target value Er (3) and the feedback gain G (3) of the third cycle, respectively.

  In each cycle, machining is performed while periodically updating the voltage command value Vc based on the deviation between the energy measurement value Em and the energy target value Er (step ST4 in FIG. 6).

  When processing the first cycle from time t6 to t7, the energy measurement value Em (from time t0 to t1) of the same cycle of the block 21 processed immediately before is fed back to the feedback gain G. Similarly, when machining in the second cycle from time t8 to t9 and the third cycle from time t10 to t11, energy measurement value Em from time t2 to t3 and energy measurement from time t4 to t5, respectively. The value Em is fed back to the feedback gain G. For example, the feedback gain G is increased or decreased based on the magnitude of the fluctuation of the energy measurement value Em.

  Next, an excellent effect obtained by mounting the laser control device 30 (FIGS. 1 and 3) on the laser processing device according to the above embodiment will be described.

  In the above embodiment, a different energy target value Er (FIG. 4) can be set for each cycle. Further, by the cycle designation signal S3, the host controller 40 notifies the laser controller 30 of what cycle the machining currently being executed is. For this reason, even when the target pulse energy differs from cycle to cycle, the laser control device 30 can perform feedback control so as to maintain the energy measurement value Em at the energy target value Er.

  In particular, in a gas laser such as a carbon dioxide laser, the gas temperature in the chamber changes when the pulse width is changed. Therefore, in order to obtain a stable output, the discharge voltage and the feedback gain G can be changed according to the pulse width. desirable. In the above embodiment, since the voltage initial value Vo and the feedback gain G (FIG. 4) are set for each cycle, a stable output can be obtained.

  When a certain cycle of one block is executed, it is fed back to the feedback gain G of the cycle to be processed next based on the energy measurement value Em of the same cycle of the block 21 processed immediately before instead of the immediately preceding cycle. For example, in the example shown in FIG. 7, the measurement results in the previous three cycles are fed back with respect to the machining in the cycle from time t6 to t7. Thus, appropriate feedback control can be performed by feeding back the measurement result of the same cycle.

Next, various modifications of the above embodiment will be described.
In the above embodiment, three cycles are executed for processing one block 21 (FIG. 2A), but other numbers of cycles may be used. For example, the metal film 24 (FIG. 2B) on the upper surface may be penetrated in the first cycle, and one cycle or three or more cycles may be executed for processing the resin layer 23 (FIG. 2B). In a plurality of cycles after the second cycle, the energy target value Er may be the same or different. For example, in order to reduce damage to the metal film 25 (FIG. 2B) on the lower surface, the energy target value Er for the cycle executed later may be set smaller than the energy target value Er for the cycle executed earlier.

  Furthermore, in the above-described embodiment, the oscillation condition parameter for each cycle is stored in the laser control device 30, so that it is not necessary to notify the laser control device 30 of the oscillation condition parameter from the host control device 40 each time the cycle is switched. When the cycle is switched, the cycle number may be notified from the host controller 40 to the laser controller 30. For this reason, it is possible to speed up the cycle switching process.

  When the time required for transferring various information between the host controller 40 and the laser controller 30 is sufficiently short, an oscillation condition parameter is transmitted from the host controller 40 to the laser controller 30 at each cycle change. You may make it do.

  In the above embodiment, drilling of the printed wiring board is performed. In addition, the laser control device 30 (FIG. 1) according to the embodiment can be applied to a laser processing apparatus that performs cycle processing using a pulse laser. .

Next, still another modification will be described with reference to FIG.
FIG. 8 shows the time of the oscillation command signal S0, the cycle designation signal S3, the energy target value Er, the energy measurement value Em, and the feedback gain G when processing is performed by the laser processing apparatus equipped with the laser control apparatus 30 according to this modification. It is a graph which shows an example of change.

  In the embodiment shown in FIG. 7, the measurement result of the same cycle of the block 21 (FIG. 2A) processed immediately before is fed back to the feedback gain G. On the other hand, in the modification shown in FIG. 8, the measurement result of the first cycle of the block 21 (FIG. 2A) processed immediately before is fed back to the feedback gain G in the process of the first cycle. The same condition as the feedback condition of the first cycle is also applied to the feedback to the feedback gain G of the second and subsequent cycles.

  The change in the correlation between the increase / decrease amount of the voltage command value Vc and the increase / decrease amount of the energy measurement value Em shows the same tendency in any cycle. Therefore, effective feedback control can also be performed in the modification shown in FIG.

  Each of the above-described embodiments is an exemplification, and needless to say, partial replacement or combination of the configurations shown in the different embodiments is possible. About the same effect by the same composition of a plurality of examples, it does not refer to every example one by one. Furthermore, the present invention is not limited to the embodiments described above. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

DESCRIPTION OF SYMBOLS 10 Laser oscillator 11 Optical system 12 Bending mirror 13 Aperture 15 Branch optical system 16A, 16B Beam scanner 17A, 17B Lens 18 Stage 19 Optical detector 20, 20A, 20B Processing target object 21 Block 22 Processing point 23 Resin layer 24 Upper surface The metal film 25 on the lower surface 26 The laser pulse 27 in the first cycle 27 The laser pulse 28 in the second cycle 28 The laser pulse 29 in the third cycle 29 Hole 30 Laser controller 31 Drive signal transmitter 32 Feedback controller 33 Parameter setting Unit 34 Cycle designation signal acquisition unit 35 Pulse energy calculation unit 40 Host controller

Claims (6)

A procedure in which a pulse laser beam is output from a laser oscillator and a pulse laser beam is sequentially incident on a plurality of processing points of a processing target one shot at a time is regarded as one cycle, and a plurality of processing points are applied to a plurality of processing points. A laser control device incorporated in a laser processing apparatus that performs laser processing by repeating a cycle,
A laser control apparatus that controls the laser oscillator so that an energy measurement value that is a measurement value of pulse energy of a pulse laser beam is maintained at an energy target value that is a target value of pulse energy set for each cycle.   2. The laser oscillator includes a discharge electrode for exciting a laser medium, and the control for maintaining the measured energy value at the energy target value includes a control for changing a discharge voltage applied to the discharge electrode. The laser control apparatus as described in.   The control for changing the discharge voltage includes control for increasing / decreasing a voltage command value, which is a command value of the discharge voltage applied to the laser oscillator, according to a deviation from the energy target value to the energy measurement value. The laser control device according to claim 2, wherein a feedback gain that is a ratio of an increase / decrease amount of the voltage command value to a deviation from a target value to the energy measurement value is set for each cycle. The surface of the object to be processed is divided into a plurality of blocks, a plurality of the processing points are defined in each of the plurality of blocks, and the laser processing apparatus repeats a plurality of cycles for each block. Laser processing,
The laser control device according to claim 3, wherein the feedback gain is updated based on the energy measurement value in the same cycle when the block that has been processed immediately before is processed. further,
The energy target value is stored for each cycle,
When a signal designating one cycle among a plurality of cycles is received from a host controller of the laser processing apparatus, the laser oscillator is controlled using the energy target value stored corresponding to the designated cycle. The laser control device according to claim 1 or 2. This is a method of performing laser processing by repeating a plurality of cycles on a plurality of the processing points, with a procedure in which a pulsed laser beam is sequentially incident on a plurality of processing points of a processing target one shot at a time. And
When performing a plurality of cycles while performing feedback control so that pulse energy is maintained at an energy target value that is a target value of pulse energy for a laser oscillator that outputs a pulsed laser beam, at least two different A laser processing method using a different value as the energy target value in a cycle.

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