TWI523357B - Laser processing device and laser processing method - Google Patents

Description

Laser processing device and laser processing method

The present application claims priority based on Japanese Patent Application No. 2013-056217, filed on March 19, 2013, and Japanese Patent Application No. 2013-067746, filed on March 28, 2013. The entire contents of this application are incorporated herein by reference.

The present invention relates to a laser processing apparatus and a laser processing method for performing laser processing by emitting a pulsed laser.

In gas lasers such as carbon dioxide lasers, impurities in the laser medium gas may affect the discharge. Therefore, the pulse energy of each of the laser pulses emitted is deviated. When the laser pulse is used for drilling, if the pulse energy is deviated, the processing quality will be inconsistent.

Patent Document 1 listed below discloses a laser oscillation method that reduces variations in pulse energy. In the method disclosed in Patent Document 1, the energy value of the laser light emitted from the laser oscillator is measured in a plurality of pulse excitations. The measured plurality of energy values are summed to predict the total energy estimate of the oscillated laser light excited by the pulse. The excitation time is controlled based on the total energy estimate. Thereby, the total energy value (pulse energy) can be stabilized.

(previous technical literature) (Patent Literature)

Patent Document 1: Japanese Laid-Open Patent Publication No. 2002-299736

When the pulse width is relatively long, for example, when it is about several hundred μs, the pulse energy can be adjusted by the method disclosed in Patent Document 1 even if the delay time from the laser oscillation command to the rise of the laser pulse is varied. However, when the pulse width is short, for example, several tens of μs, it is difficult to control the excitation time in consideration of the energy detection sensitivity and the calculation time.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a laser processing apparatus and a laser processing method capable of stabilizing the pulse energy of each pulse even when the pulse width is short.

According to an aspect of the present invention, a laser processing apparatus is provided, comprising: a laser light source, starting with a laser oscillation received from an external start to trigger a laser oscillation, and stopping the laser oscillation in synchronization with a laser oscillation stop trigger a detector that detects a physical quantity of at least one of a power applied to the aforementioned laser light source and a laser pulse emitted from the aforementioned laser light source; The control device applies the aforementioned laser oscillation start trigger to the laser light source, and applies the oscillation stop trigger to the laser light source based on the detection result of the physical quantity detected by the detector.

According to another aspect of the present invention, a laser processing method is provided, which has a process of applying an externally received oscillation start trigger to a laser light source, and the laser light source starts the laser in synchronization with the aforementioned oscillation start trigger. Oscillation, and stopping the laser oscillation in synchronization with the oscillation stop trigger; detecting a process depending on the power applied to the aforementioned laser light source and the physical quantity of at least one of the laser pulses emitted from the aforementioned laser light source; and the detection result according to the aforementioned physical quantity And applying the aforementioned oscillation stop triggering process to the aforementioned laser light source.

The oscillation stop trigger is applied to the laser light source based on the detection result of the physical quantity detected by the detector, whereby the pulse energy can be stabilized.

1‧‧‧Laser light source

10‧‧‧Laser oscillator

11‧‧‧Drive circuit

12‧‧‧ Spot Position Stabilization Optical System

13‧‧‧Aspherical lens

14‧‧‧ Collimating lens

15‧‧‧Photomask

16‧‧ ‧ field lens

17‧‧‧Mirror

18‧‧‧ Beam Scanner

19‧‧‧fθ lens

20‧‧‧Control device

20A‧‧‧ Function block for receiving measured values of physical quantities

20B‧‧‧ Conditions data for constant pulse energy

20C‧‧‧Modify the function block at the moment of transmitting the oscillation stop trigger

20D‧‧‧Trigger generation function block

21‧‧‧Partial mirror

22‧‧‧Photodetector

25‧‧‧ stage

30‧‧‧Processing objects

40‧‧‧Air blower

41‧‧‧Discharge electrode

42‧‧‧Discharge space

43‧‧‧Electrical components

44‧‧‧Ceramic components

46‧‧‧ heat exchanger

50‧‧‧ chamber

51‧‧‧ terminals

52‧‧‧In-chamber current circuit

55‧‧‧Outdoor outdoor current path

56‧‧‧Detector

Fig. 1 is a schematic view showing a laser processing apparatus of the first embodiment.

Fig. 2 is a cross-sectional view showing a laser oscillator of the laser processing apparatus of the first embodiment and a block diagram of the drive circuit.

Figure 3 is a timing diagram of a trigger signal applied from a control device to a laser source, a high frequency voltage applied to a discharge electrode of a laser oscillator, a discharge current flowing through a discharge electrode, and a light output from a laser oscillator. .

Fig. 4 is a diagram showing the delay time and pulse until the laser pulse rises from the time when the laser oscillation is applied to the laser light source to the time when the triggering time width of the laser oscillation stop trigger is set to be constant. A graph of the relationship of energy.

Fig. 5 is a flow chart showing the processing executed by the control device of the laser processing apparatus of the first embodiment.

Figure 6 is a timing diagram of a trigger signal applied from a control device to a laser source, a high frequency voltage applied to a discharge electrode of a laser oscillator, a discharge current flowing through a discharge electrode, and a light output from a laser oscillator. .

Fig. 7 is a schematic view showing a laser processing apparatus of the second embodiment.

Figure 8 is a cross-sectional view showing a laser oscillator used in the laser processing apparatus of Embodiment 2 and a block diagram of the control system.

Figure 9 is a timing diagram of the trigger signal, high frequency voltage, discharge current, and light output.

In Fig. 10, Fig. 10A is a graph showing the relationship between the peak value of the discharge current and the pulse energy, and Fig. 10B is a graph showing the relationship between the application time of the high-frequency voltage and the pulse energy.

Fig. 11 is a graph showing the relationship between the peak value of the discharge current and the application time of the high-frequency voltage under the condition that the pulse energy is made constant.

Fig. 12 is a flow chart showing the processing executed by the control device of the laser processing apparatus of the second embodiment.

Figure 13 is a timing diagram of the trigger signal, high frequency voltage, discharge current, and light output.

Fig. 1 is a schematic view showing a laser processing apparatus of the first embodiment. The laser light source 1 starts the laser oscillation with the start of the laser oscillation received from the control device 20, and stops the laser oscillation in synchronization with the laser oscillation stop trigger. If the laser oscillation is started, the laser light source 1 emits a laser pulse.

The laser light source 1 includes a laser oscillator 10 and a drive circuit 11. The laser oscillator 10 is a gas laser oscillator using, for example, a carbon dioxide laser oscillator. A laser oscillation start trigger and a laser oscillation stop trigger are applied to the drive circuit 11 from the control device 20. When the drive circuit 11 receives the laser oscillation start trigger, power supply to the laser oscillator 10 is started. When the laser oscillation stop trigger is received, the supply of power to the laser oscillator 10 is stopped.

The laser beam emitted from the laser light source 1 is divided into a transmitted beam and a reflected beam by a partial mirror 21. The reflected beam is incident on the photodetector 22. When the photodetector 22 detects light, it transmits a detection signal to the control device 20. The control device 20 determines the timing at which the laser oscillation stop trigger is applied to the laser light source 1 based on the timing at which the detection signal is received from the photodetector 22, that is, the rising timing of the laser pulse. At the determined time, a laser oscillation stop trigger is applied to the laser light source 1.

The transmitted light beam directly passing through the partial mirror 21 passes through the spot position stabilizing optical system 12 and enters the aspherical lens 13. The spot position stabilization optical system 12 includes a plurality of convex lenses, and even if the traveling direction of the laser beam emitted from the laser light source 1 is deviated, the position of the electron beam spot where the aspherical lens 13 is disposed can be stabilized. The aspherical lens 13 can change the profile of the laser beam. For example, a Gaussian shaped beam profile can be changed A beam profile in the shape of a flat top.

The laser beam transmitted through the aspherical lens 13 is collimated by the collimator lens 14, and then incident on the mask 15. The photomask 15 includes a transmission window and a light shielding portion to shape a beam cross section of the laser beam. The laser beam transmitted through the transmission window of the reticle 15 is incident on the beam scanner 18 via the field lens 16 and the mirror 17. The beam scanner 18 scans the laser beam in a two dimensional direction. As the beam scanner 18, for example, a current scanner can be used.

The laser beam scanned by the beam scanner 18 is condensed by the fθ lens 19 and incident on the object 30. The object 30 is held on the stage 25. The field lens 16 and the fθ lens 19 image the transmission window of the mask 15 on the surface of the object 30. The stage 25 moves the object 30 in a direction parallel to the surface thereof.

Fig. 2 is a cross-sectional view showing the laser oscillator 10 of the first embodiment and a block diagram of the driving circuit. A blower 40, a pair of discharge electrodes 41, a heat exchanger 46, and a laser medium gas are housed inside the chamber 50. A discharge space 42 is defined between the pair of discharge electrodes 41. The laser medium gas is excited by generating a discharge in the discharge space 42. In the second drawing, a cross section orthogonal to the longitudinal direction of the discharge electrode 41 is shown. The blower 40 uses, for example, a turbo blower. In addition, a cross flow fan, an axial fan, or the like may be used instead of the turbo blower. Each of the discharge electrodes 41 includes a conductive member 43 and a ceramic member 44. The ceramic member 44 isolates the conductive member 43 from the discharge space 42.

A circulation path is formed in the chamber 50, and the circulation path is returned from the blower 40 through the discharge space 42 between the discharge electrodes 41 and the heat exchanger 46 to the blower 40. The heat exchanger 46 is used for cooling to become discharged by discharge High temperature laser medium gas.

A pair of terminals 51 are mounted on the wall surface of the chamber 50. The conductive members 43 of the discharge electrodes 41 are connected to the terminals 51 via the intra-chamber current paths 52, respectively. The terminal 51 is connected to the drive circuit 11 via the outdoor cavity current path 55.

Fig. 3 shows a trigger signal applied to the drive circuit 11 (Fig. 1) from the control device 20 (Fig. 1), a high-frequency voltage applied to the discharge electrode 41 (Fig. 2), and a discharge electrode 41. The discharge current and the timing diagram of the light output from the laser oscillator 10 (Fig. 1).

The trigger signal rises at time t1. The rise of the trigger signal is equivalent to the start of the laser oscillation. At time t1, when the drive circuit 11 receives the laser oscillation start trigger, the drive circuit 11 applies a high-frequency voltage to the discharge electrode 41. The frequency of the high frequency voltage is, for example, 2 MHz. When a high-frequency voltage is applied, if discharge starts at time t2, the discharge current starts to flow.

After the start of discharge, the light output (laser pulse) rises at a time t3 when the gain in the optical resonator of the laser oscillator 10 exceeds the loss. That is, the laser pulse rises at time t3 after the delay time Td elapses from the time t1 at which the application of the laser oscillation is triggered. The light output is stable after a sharp peak is displayed momentarily as it rises. When the laser pulse rises, light is detected by the photodetector 22 (Fig. 1), and the detection signal is transmitted to the control device 20 (Fig. 1).

The control device 20 determines the timing t4 at which the laser oscillation stop trigger is applied to the laser light source 1 based on the timing at which the detection signal is received from the photodetector 22, that is, the rising timing t3 of the laser pulse. For example, the pulse width Pd from the detection time t3 to the time t4 of the laser pulse becomes constant. The formula determines the time t4.

The control device 20 lowers the trigger signal at time t4, thereby applying a laser oscillation stop trigger to the laser light source 1. When the drive circuit 11 receives the laser oscillation stop trigger from the control device 20, the drive circuit 11 stops the application of the high frequency voltage. If a high-frequency voltage is not applied to the discharge electrode 41, the discharge is stopped, the discharge current does not flow, and the light output becomes 0 (the laser pulse falls). The time width from time t3 to time t4 corresponds to the pulse width Pd of the laser pulse. The elapsed time from the time t1 at which the start of the laser oscillation is triggered to the time t4 at which the laser oscillation stop trigger is applied is referred to as the trigger time width Te.

Fig. 4 shows the relationship between the delay time Td when the control is performed under the condition that the trigger time width Te is constant, and the pulse energy of the laser pulse. The horizontal axis represents the delay time Td, and the vertical axis represents the pulse energy. The trigger time width Te is constant, so the sum of the delay time Td and the pulse width Pd (Fig. 3) is constant. Therefore, if the delay time Td becomes long, the pulse width Pd becomes short. The pulse energy is reduced by the pulse width Pd becoming shorter. It can be seen that if the laser oscillation is controlled such that the trigger time width Te becomes constant, the pulse energy is not uniform due to the variation of the delay time Td.

Next, a laser processing method using the laser processing apparatus of the first embodiment will be described with reference to FIGS. 5 and 6. Before the laser processing, the object to be processed 30 is first held on the stage 25 (first drawing) and the stage 25 is moved, whereby the object 30 is positioned. In the object 30, a plurality of processed points are defined in a range that can be scanned by the beam scanner 18. In laser processing, control device 20 controls beam scanning The device 18 sequentially injects a laser pulse into the workpiece to be processed on the object 30, thereby performing drilling processing.

Fig. 5 is a flow chart showing the processing executed by the control device 20 (Fig. 1) of the laser processing apparatus of the first embodiment. A timing chart of the trigger signal, the high frequency voltage, the discharge current, and the light output is shown in FIG. When the object 30 is held on the stage 25 and the positioning of the object 30 is completed, the beam scanner 18 is controlled so that the laser pulse is incident on the workpiece to be processed. Standby in step S1 until the positioning of the beam scanner 18 is completed. If the positioning of the beam scanner 18 is completed, a laser oscillation start trigger is applied to the laser light source 1 in step S2. Step S2 corresponds to times t11, t21, and t31 shown in Fig. 6.

When a laser oscillation start trigger is applied to the laser light source 1, a high frequency voltage is applied to the laser oscillator 10 (Fig. 1), and a discharge current flows. The laser pulses Lp1, Lp2, and Lp3 rise at times t12, t22, and t32 at which the delay times Td1, Td2, and Td3 have elapsed from the times t11, t21, and t31 at which the laser oscillation is started. The delay times Td1, Td2, and Td3 are not necessarily all equal due to the influence of the vibration of the mirror of the optical resonator or the impurities contained in the laser medium gas. Fig. 6 shows an example in which the magnitude relationship of the delay time is Td3 < Td1 < Td2.

In step S3, the delay times Td1, Td2, and Td3 from the application of the laser oscillation stop trigger to the rise of the laser pulse are measured. Specifically, the control device 20 measures an elapsed time from the time when the laser light source 1 is applied to start the trigger of the laser oscillation to the time when the detection signal is received by the photodetector 22.

It is determined in step S4 whether or not the delay time Td is within the specification. Delay When the inter-Td is outside the specification, a laser oscillation stop trigger is applied to the laser light source 1 in step S8. Thereby, the supply of electric power to the discharge electrode 41 (Fig. 1) is stopped. By stopping the supply of electric power, abnormal oscillation can be prevented.

When the delay time Td is within the specification, in step S5, the timings t13 and t23 at which the laser oscillation stop trigger is applied to the laser light source 1 are calculated based on the rising times t12, t22, and t32 (Fig. 6) of the laser pulses. , t33 (Fig. 6). Specifically, the time after the rising time t12, t22, and t32 of the laser pulse passes the time corresponding to the target pulse width Pd is taken as the timings t13, t23, and t33 at which the laser oscillation stop trigger is applied. The target pulse width Pd is previously stored in the control device 20.

In step S6, a laser oscillation stop trigger is applied to the laser light source 1 at times t13, t23, and t33 (Fig. 6) calculated in step S5. Thereby, the laser pulses Lp1, Lp2, and Lp3 are lowered.

It is determined in step S7 (Fig. 5) whether or not the machining is finished. When the unprocessed machined point remains, the beam scanner 18 is controlled to inject the laser pulse into the next processed point to be processed, and the process returns to step S1. If the machining of all the machining points has been completed, the laser processing is ended.

In the example shown in Fig. 6, when the timing control is performed such that the trigger time widths Te1, Te2, and Te3 are the same, the pulse width from the rising time to the falling time of the laser pulse is subjected to the delay times Td1, Td2, and Td3. The effect of the deviation leads to inhomogeneity.

In the first embodiment, it is determined that laser light is applied to the laser light source 1 based on the rising timings t12, t22, and t32 (Fig. 6) of the laser pulses. The timings at which the triggering is stopped are t13, t23, and t33 (Fig. 6). Therefore, the pulse width Pd of the laser pulse is not affected by the deviation of the delay times Td1, Td2, and Td3. Therefore, even if the delay times Td1, Td2, and Td3 are deviated, the pulse width Pd can be made constant. As a result, the variation in pulse energy is small. When the elapsed time from the rising timings t12, t22, and t32 of the laser pulse to the times t13, t23, and t33 at which the laser oscillation stop trigger is applied is made constant, the pulse energy can be made substantially uniform.

Since the pulse width Pd is stored in advance in the control device 20 (Fig. 1), it is not necessary to perform calculation for determining the target pulse width or the like after detecting the rise of the laser pulse. The method for determining the pulse width of the laser pulse based on the measurement result after the rise of the laser pulse is not applicable to laser processing using a laser pulse having a pulse width shorter than the calculation time. In the above-described first embodiment, the calculation for determining the pulse width is not required, and therefore the pulse width Pd is not limited by the calculation time. Further, in the first embodiment described above, it is not necessary to measure the light energy or the like after the rise of the laser pulse, and it is only necessary to detect whether or not there is a laser pulse. Therefore, it is not necessary to ensure the measurement time for performing high-accuracy light energy measurement. For the above reasons, the first embodiment described above can also be applied to laser processing in which the pulse width Pd is short, for example, in laser processing in which the pulse width is shorter than several tens of μs.

Fig. 7 is a schematic view showing a laser processing apparatus of the second embodiment. The laser oscillator 10 receives the supply of electric power from the drive circuit 11 and emits a pulsed laser beam. The laser oscillator 10 is a gas laser oscillator using, for example, a carbon dioxide laser oscillator. The drive circuit 11 supplies and supplies power to the laser oscillator 10 in synchronization with a trigger signal from the control device 20. stop.

The laser beam emitted from the laser oscillator 10 passes through the spot position stabilization optical system 12 and enters the aspherical lens 13. The configuration of the optical system from the spot position stabilization optical system 12 to the stage 25 is the same as that of the optical system from the spot position stabilization optical system 12 to the stage 25 shown in Fig. 1 .

Next, the configuration of the control device 20 will be briefly described. The detailed processing performed by the control device 20 will be described later with reference to FIGS. 12 and 13. The control device 20 has a function block 20A that receives a measured value of a physical quantity supplied to at least one of a current and a voltage of the laser oscillator 10. The control device 20 stores condition data 20B that makes the pulse energy constant. The function block 20C that adjusts the timing at which the oscillation stop trigger is transmitted by the control device 20 is a timing at which the transmission oscillation stop trigger is adjusted based on the measured value of the physical quantity and the condition data 20B that makes the pulse energy constant.

The trigger generation function block 20D of the control device 20 transmits an oscillation stop trigger to the drive circuit 11 at the timing when the function block 20C at the timing of transmitting the oscillation stop trigger is adjusted. By adjusting the timing at which the transmission oscillation stops triggering, the variation of the pulse energy can be suppressed, and the pulse energy can be made uniform.

Fig. 8 is a cross-sectional view showing the laser oscillator 10 of the second embodiment and a block diagram of the control system. The structure of the inside of the chamber 50 and the outdoor current path 55 is the same as that of the inside of the chamber 50 and the outdoor current path 55 shown in Fig. 2 .

The detector 56 measures the current flowing through the outdoor circuit 55 of the chamber. Detector The measured value of the 56 measured current is input to the control device 20. The control device 20 controls the drive circuit 11 based on the measured value of the current detected by the detector 56.

Fig. 9 shows a trigger signal applied to the drive circuit 11 (Fig. 7) from the control device 20 (Fig. 7), a high-frequency voltage applied to the discharge electrode 41 (Fig. 8), and flowing through the discharge electrode 41. The discharge current, and the timing diagram of the light output from the laser oscillator 10 (Fig. 7).

The trigger signal rises at time t1. The rise of the trigger signal is equivalent to the start of the oscillation. At time t1, when the drive circuit 11 receives the oscillation start trigger, the drive circuit 11 applies a high-frequency voltage to the discharge electrode 41. The frequency of the high frequency voltage is, for example, 2 MHz. When a high-frequency voltage is applied, if discharge starts at time t2, the discharge current starts to flow.

After the start of discharge, the light output (laser pulse) rises at a time t3 when the gain in the optical resonator of the laser oscillator 10 exceeds the loss. The light output is stable after a sharp peak is displayed momentarily as it rises.

In the transient state immediately after the start of the discharge, the amplitude of the discharge current is smaller than the amplitude at the steady state, and gradually increases as time elapses. After the light output rises at time t3, the discharge current becomes a stable state in which the amplitude is substantially constant.

The trigger signal drops at time t4. The falling of the trigger signal is equivalent to the oscillation stop trigger. When the drive circuit 11 receives the oscillation stop trigger from the control device 20, the drive circuit 11 stops the application of the high-frequency voltage. If a high-frequency voltage is not applied to the discharge electrode 41, the discharge is stopped, the discharge current does not flow, and the light output becomes 0 (the laser pulse falls). The time width from time t3 to time t4 corresponds to the pulse width of the laser pulse.

The excitation intensity of the laser medium gas is proportional to the power input. The pulse energy of the pulsed laser beam emitted from the laser oscillator is proportional to the excitation intensity under a condition that the pulse width is constant. Therefore, the pulse energy can be predicted based on the input power, that is, the high frequency voltage and the discharge current.

FIG. 10A shows the relationship between the peak value Ipp of the discharge current and the pulse energy under the condition that the high-frequency voltage application time (time from time t1 to time t4) is constant. Here, the peak value Ipp of the discharge current corresponds to twice the amplitude of the discharge current. The horizontal axis of Fig. 10A indicates the peak value Ipp in the steady state, and the vertical axis indicates the pulse energy. As the peak Ipp of the discharge current becomes larger, the pulse energy also increases, and there is a substantially linear relationship between the two.

When the discharge current is in a steady state, the peak value Ipp of the discharge current is substantially constant. Therefore, the pulse energy of the laser pulse can be predicted by measuring the peak value Ipp of the discharge current from the start of discharge to the time before the stop of the discharge.

In Fig. 10B, the relationship between the peak value Ipp of the discharge current and the high-frequency voltage application time (time from time t1 to t4 in Fig. 9) under constant conditions and the pulse energy is shown. The horizontal axis represents the high frequency voltage application time, and the vertical axis represents the pulse energy. As the application time of the high-frequency voltage becomes longer, the pulse energy becomes larger, and there is a substantially linear relationship between the two.

The following phenomenon can be derived from the graphs shown in Fig. 10A and Fig. 10B. When the peak value Ipp of the discharge current becomes small, the pulse energy also becomes small. If the high-frequency voltage application time is increased to compensate for the amount of reduction in pulse energy, the pulse energy can be maintained constant. According to the graphs shown in FIG. 10A and FIG. 10B, it can be found that the pulse energy is maintained. It is a correspondence relationship between the peak Ipp of the constant discharge current and the application time of the high-frequency voltage.

Fig. 11 shows the correspondence relationship between the peak Ipp of the discharge current for maintaining the pulse energy constant and the high-frequency voltage application time. The horizontal axis represents the peak value Ipp of the discharge current, and the vertical axis represents the high-frequency voltage application time. As the peak value Ipp of the discharge current becomes larger, the application time of the high-frequency voltage becomes shorter. The correspondence shown in Fig. 11 is stored in advance in the control device 20 (Fig. 7). This correspondence relationship corresponds to the condition data 20B which makes the pulse energy constant as shown in Fig. 7.

Next, a laser processing method using the laser processing apparatus of the second embodiment will be described with reference to Figs. 12 and 13. Before the laser processing, the object 30 is first held on the stage 25 (Fig. 7) and the stage 25 is moved, whereby the object 30 is positioned. In the object 30, a plurality of processed points are defined in a range that can be scanned by the beam scanner 18. In the laser processing, the control device 20 controls the beam scanner 18 to sequentially project a laser pulse on the workpiece to be processed on the object 30, thereby performing drilling processing.

Fig. 12 is a flow chart showing the processing executed by the control device 20 (Fig. 7) of the laser processing apparatus of the second embodiment. A timing chart of the trigger signal, the high frequency voltage, the discharge current, and the light output is shown in FIG. When the object 30 is held on the stage 25 and the positioning of the object 30 is completed, the beam scanner 18 is controlled to inject the laser pulse into the processed point to be processed first. Standby in step S11 until the positioning of the beam scanner 18 is completed. If the positioning of the beam scanner 18 is completed, Then, in step S12, an oscillation start trigger (a command for starting the power supply) is applied to the drive circuit 11. Step S12 corresponds to times t11, t21, and t31 shown in Fig. 13.

Each of the laser pulses Lp1, Lp2, and Lp3 rises after the application start timings t11, t21, and t31 of the high-frequency voltage.

The peak Ipp of the discharge current is measured in step S13 until a predetermined determination time Tj (Fig. 13) is passed. This measurement is performed using the detector 56 (Fig. 8). The determination time Tj is shorter than the rated pulse width of the laser pulse to be emitted. As an example, the rated pulse width is 50 μs and the determination time Tj is 5 μs. When the frequency of the high-frequency voltage is 2 MHz, the determination time Tj of 5 μs corresponds to the amount of 10 cycles of the high-frequency voltage.

The measurement of the peak value Ipp of the discharge current is started after the discharge current has reached a steady state. When the discharge current is in a steady state at about three cycles, the peak Ipp from the fourth cycle to the tenth cycle is measured.

The peaks of the discharge currents generated by the oscillation start triggers at times t11, t21, and t31 shown in Fig. 13 are indicated by Ipp1, Ipp2, and Ipp3, respectively. In the example shown in Fig. 13, the magnitude relationship of the three peaks is Ipp2 < Ipp1 < Ipp3.

In step S14 (Fig. 12), it is determined whether or not the peak value Ipp of the discharge current is within the specification. When the measured peak value Ipp is outside the specification, the supply of electric power to the discharge electrode 41 (Fig. 7) is stopped in step S18. By stopping the supply of electric power, abnormal oscillation can be prevented.

When the measured peak Ipp is within the specification, the time width from the oscillation start trigger to the oscillation stop trigger is calculated based on the peak Ipp in step S15. degree. Hereinafter, an example of the processing of step S15 will be described. For example, the average value of the plurality of peaks Ipp measured during the determination time Tj (Fig. 13) is obtained. The high-frequency voltage application time is obtained from the correspondence between the average value of the peak Ipp and the relationship shown in FIG.

The time widths Pd1, Pd2, and Pd3 corresponding to the peaks Ipp1, Ipp2, and Ipp3 are obtained from the correspondence shown in Fig. 11. The magnitude relationship of these time widths is Pd3 < Pd1 < Pd2.

In step S16 (Fig. 12), the oscillation stop trigger (command for stopping the power supply) is transmitted at a point in time after the time width obtained in step S15 has elapsed from the start of the oscillation. In Fig. 13, the oscillation stop trigger is transmitted at times t12, t22, and t32. The time width from time t11 to time t12 is equal to Pd1, the time width from time t21 to time t22 is equal to Pd2, and the time width from time t31 to t32 is equal to Pd3. The discharge is stopped at times t12, t22, and t32, and the respective laser pulses Lp1, Lp2, and Lp3 are lowered.

In step S17 (Fig. 12), it is determined whether or not the machining is finished. When the unprocessed machined point remains, the beam scanner 18 is controlled to inject the laser pulse into the next processed point to be processed, and the process returns to step S11. If the machining of all the machining points has been completed, the laser processing is ended.

The light output of the laser pulse Lp2 in the steady state is lower than the light output of the laser pulse Lp1. By making the pulse width of the laser pulse Lp2 longer than the pulse width of the laser pulse Lp1, the amount of decrease in the light output can be compensated. Moreover, the light output of the laser pulse Lp3 in a steady state is higher than that of the laser pulse Lp1 Output. By making the pulse width of the laser pulse Lp3 shorter than the pulse width of the laser pulse Lp1, the amount of increase in the light output can be compensated. Since the time width from the oscillation start trigger to the oscillation stop trigger is determined according to the correspondence relationship shown in FIG. 11, the pulse energies of the laser pulses Lp1, Lp2, and Lp3 can be made uniform.

When the peak value Ipp of the discharge current is larger, the time width from the oscillation start trigger to the oscillation stop trigger is shortened, whereby the pulse energy of the laser pulse can be made nearly uniform.

The peak Ipp of the discharge current can be easily measured in a short time compared to the light output. Therefore, the method of the second embodiment can shorten the determination time Tj (FIG. 13) as compared with the case where the pulse width is adjusted by measuring the light output. Therefore, the method of the above-described second embodiment can be applied even if the pulse width of the laser pulse to be emitted is 100 μs or less.

In the second embodiment described above, the peak value Ipp of the discharge current is measured during the determination period Tj, but other physical quantities depending on the power supplied to the discharge electrode 41 (Fig. 8) may be measured. For example, the effective value of the discharge current can be measured.

When the discharge state changes, the voltage applied between the pair of discharge electrodes 41 also changes. This change in voltage follows a change in the power supplied to the discharge electrode 41. Therefore, as another physical quantity depending on the electric power supplied to the discharge electrode 41 (Fig. 8), a peak value or an effective value of a voltage applied between the discharge electrodes 41 may be employed. In this manner, it is sufficient to measure at least one physical quantity of the voltage or current applied to the discharge electrode 41.

The present invention has been described based on the above embodiments, but the present invention is not limited thereto. These embodiments are set forth. For example, various changes, modifications, combinations, and the like can be made, as will be apparent to those of ordinary skill in the art.

1‧‧‧Laser light source

10‧‧‧Laser oscillator

11‧‧‧Drive circuit

12‧‧‧ Spot Position Stabilization Optical System

13‧‧‧Aspherical lens

14‧‧‧ Collimating lens

15‧‧‧Photomask

16‧‧ ‧ field lens

17‧‧‧Mirror

18‧‧‧ Beam Scanner

19‧‧‧fθ lens

20‧‧‧Control device

21‧‧‧Partial mirror

22‧‧‧Photodetector

25‧‧‧ stage

30‧‧‧Processing objects

Claims (11)

A laser processing device has a laser light source, starts to trigger a synchronization with an oscillation received from an external oscillation, and stops a laser oscillation synchronously with an oscillation stop trigger; the detector is detected depending on the aforementioned laser light source a physical quantity of at least one of the applied electric power and the laser pulse emitted from the laser light source; and a control device applying the oscillation start trigger to the laser light source, and based on the detection result of the physical quantity detected by the detector The aforementioned oscillation stop trigger is applied to the aforementioned laser light source within the same pulse. The laser processing apparatus according to claim 1, wherein the detector detects a laser pulse emitted from the laser light source, and the control device detects a laser pulse detected by the detector as The reference determines a timing at which the oscillation stop trigger is applied to the laser light source, and the oscillation stop trigger is applied to the laser light source at the determined timing. The laser processing apparatus according to claim 2, wherein the control device stores a target pulse width of the laser pulse to be emitted, and passes the detection time of the laser pulse detected from the detector. The oscillation stop trigger is applied to the laser light source at a time after the time when the target pulse width is equal. a laser processing apparatus according to claim 1, wherein The laser light source has: a laser medium gas; a discharge electrode that excites the laser medium gas; and a driving circuit that starts to supply the electric power to the discharge electrode by receiving the oscillation start trigger, and stops by receiving the oscillation Triggering to stop supplying electric power to the discharge electrode, wherein the physical quantity is at least one of a voltage and a current applied to the discharge electrode, and the control device detects the oscillation start trigger on the drive circuit, and then detects the The detected value of the physical quantity applies the aforementioned oscillation stop trigger to the aforementioned drive circuit. The laser processing apparatus according to claim 4, wherein the control device detects the detection by the detector before the predetermined determination time after applying the oscillation start trigger to the drive circuit As a result of the detection, the time width from the start of the application of the oscillation start trigger to the application of the oscillation stop trigger is calculated. The laser processing apparatus according to claim 4, wherein the control device shortens the trigger from the start of the oscillation to the trigger of the oscillation stop when the physical quantity detected by the detector is larger. Time width. A laser processing apparatus as described in claim 4 or 5, The control device stores a correspondence relationship between the physical quantity measured by the detector and a time from the oscillation start trigger to the oscillation stop trigger, and the detected value of the physical quantity detected by the detector corresponds to the foregoing For the relationship, the time width from the start of the oscillation start to the oscillation stop trigger is obtained. A laser processing method has the following process: applying a process of triggering an oscillation received from the outside to a laser light source, the laser light source starts to perform laser oscillation in synchronization with the start of the oscillation start, and stops synchronously with the oscillation stop trigger. a laser oscillation; a process of detecting a physical quantity of at least one of a power applied to the laser light source and a laser pulse emitted from the laser light source; and the laser in the same pulse according to the detection result of the physical quantity The light source applies the aforementioned process of oscillating the stop trigger. The laser processing method of claim 8, wherein in the process of detecting the physical quantity, detecting a rising timing of the laser pulse emitted from the laser light source, in a process of applying the oscillation stop trigger The oscillation stop trigger is applied to the laser light source at a timing after a time corresponding to a predetermined target pulse width from a rising timing of the laser pulse. The laser processing method of claim 8, wherein The laser light source includes a discharge electrode, and the physical quantity detected in the process of detecting the physical quantity is at least one of a voltage or a current applied to the discharge electrode, and the process of applying the oscillation stop trigger includes: according to the detected value of the physical quantity, The process of calculating the time width of the electric power supplied to the discharge electrode, and the process of applying the oscillation stop trigger to the laser light source at a time point after the calculated time width from the time when the oscillation start trigger is applied. The laser processing method according to claim 10, wherein, in the process of calculating the time width, the voltage or current from a time point when the oscillation start is applied to a predetermined determination time The detected value is calculated to calculate the aforementioned time width.