KR101617080B1 - Laser processing apparatus and laser processing method - Google Patents

Abstract

Provided is a laser machining apparatus capable of stabilizing pulse energy for each pulse even when the pulse width is short.
The laser light source starts laser oscillation in synchronization with the laser oscillation start trigger received from the outside, and stops the laser oscillation in synchronization with the laser oscillation stop trigger. The detector detects a physical quantity depending on at least one of the power given to the laser light source and the laser pulse emitted from the laser light source. The control device gives a laser oscillation start trigger to the laser light source and gives an oscillation stop trigger to the laser light source based on the detection result of the physical quantity by the detector.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a laser processing apparatus and a 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 which are incorporated herein by reference.

TECHNICAL FIELD [0001] The present invention relates to a laser machining apparatus for performing laser machining by emitting a pulse laser, and a laser machining method.

In a gas laser such as a carbon dioxide gas laser, impurities in the laser medium gas affect the discharge. As a result, a deviation occurs in the pulse energy for each laser pulse to be emitted. When the laser pulse is used for punching, if the pulse energy deviates, the processing quality becomes uneven.

Patent Literature 1 described below discloses a laser oscillation method for reducing the deviation of pulse energy. In the method disclosed in Patent Document 1, the energy value of the laser beam emitted from the laser oscillator is measured plural times during one pulse excitation. Adds the measured plurality of energy values, and predicts an estimated total energy value of the laser light oscillated by the pulse excitation. Based on this estimated total energy value, excitation time is controlled. This makes it possible to stabilize the total energy value (pulse energy).

Japanese Patent Laid-Open No. 2002-299736

When the pulse width is relatively long, for example, about several hundreds of microseconds, it is possible to adjust the pulse energy 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 uneven Do. However, when the pulse width is short, for example, several tens of microseconds, it is difficult to control the excitation time in consideration of energy detection sensitivity and computation time.

An object of the present invention is to provide a laser processing apparatus and a laser processing method capable of stabilizing pulse energy for each pulse even when the pulse width is short.

According to one aspect of the present invention,

A laser light source for starting laser oscillation in synchronization with a laser oscillation start trigger received from the outside and for stopping laser oscillation in synchronization with the laser oscillation stop trigger,

A detector for detecting a physical quantity depending on at least one of a power given to the laser light source and a laser pulse emitted from the laser light source;

And a control unit which gives the laser oscillation start trigger to the laser light source and gives the oscillation stop trigger to the laser light source based on the detection result of the physical quantity by the detector

Is provided.

According to another aspect of the present invention,

A step of giving the oscillation start trigger to a laser light source that starts laser oscillation in synchronization with an oscillation start trigger received from the outside and stops laser oscillation in synchronization with the oscillation stop trigger;

A step of detecting a physical quantity depending on at least one of an electric power given to the laser light source and a laser pulse emitted from the laser light source;

A step of giving the oscillation stop trigger to the laser light source based on the detection result of the physical quantity

Is provided.

By providing an oscillation stop trigger to the laser light source based on the detection result of the physical quantity by the detector, the pulse energy can be stabilized.

1 is a schematic view of a laser machining apparatus according to a first embodiment.
Fig. 2 is a cross-sectional view of the laser oscillator of the laser machining apparatus according to the first embodiment, and a block diagram of the drive circuit. Fig.
3 is a timing chart of a trigger signal given to the laser light source from the control device, a high-frequency voltage applied to the discharge electrode of the laser oscillator, a discharge current flowing through the discharge electrode, and a light output from the laser oscillator.
4 is a graph showing the relationship between the delay time until the rise of the laser pulse under the condition that the trigger time width from the time at which the laser oscillation start trigger is given to the laser light source to the time at which the laser oscillation stop trigger is given is constant, FIG.
5 is a flowchart of processing executed by the control apparatus of the laser machining apparatus according to the first embodiment.
6 is a timing chart of a trigger signal given to the laser light source from the control device, a high-frequency voltage applied to the discharge electrode of the laser oscillator, a discharge current flowing through the discharge electrode, and a light output from the laser oscillator.
7 is a schematic view of a laser machining apparatus according to a second embodiment.
8 is a cross-sectional view of a laser oscillator used in the laser machining apparatus according to the second embodiment and a block diagram of the control system.
9 is a timing chart of a trigger signal, a high-frequency voltage, a discharge current, and an optical output.
10A is a graph showing the relationship between the peak value of the discharge current and the pulse energy.
10B is a graph showing the relationship between the high-frequency voltage application time and the pulse energy.
11 is a graph showing the relationship between the peak value of the discharge current and the high-frequency voltage application time under the condition that the pulse energy is kept constant.
12 is a flowchart of a process executed by the control device of the laser machining apparatus according to the second embodiment.
13 is a timing chart of a trigger signal, a high-frequency voltage, a discharge current, and an optical output.

1 is a schematic view of a laser machining apparatus according to a first embodiment. The laser light source 1 starts laser oscillation in synchronization with the laser oscillation start trigger received from the control device 20 and stops the laser oscillation in synchronization with the laser oscillation stop trigger. When the laser oscillation starts, the laser light source 1 emits a laser pulse.

The laser light source 1 includes a laser oscillator 10 and a drive circuit 11. For the laser oscillator 10, for example, a gas laser oscillator such as a carbon dioxide gas laser oscillator is used. A laser oscillation start trigger and a laser oscillation stop trigger are given from the control device 20 to the drive circuit 11. [ When the drive circuit 11 receives the laser oscillation start trigger, the drive circuit 11 starts supplying power to the laser oscillator 10. Upon receiving the laser oscillation stop trigger, the supply of power to the laser oscillator 10 is stopped.

The laser beam emitted from the laser light source 1 is split into the transmission beam and the reflection beam by the partial reflecting mirror 21. [ The reflected beam is incident on the photodetector 22. The photodetector 22 sends a detection signal to the control device 20 when it detects light. The control device 20 determines the time at which the laser oscillation stop trigger is given to the laser light source 1 based on the time at which the detection signal is received from the photodetector 22, that is, the rising time of the laser pulse. At the determined time, a laser oscillation stop trigger is given to the laser light source 1.

The transmission beam that travels straight through the partial reflecting mirror 21 is transmitted 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 detects the position of the beam spot at the position where the aspheric lens 13 is disposed even if the traveling direction of the laser beam emitted from the laser light source 1 is out of order . The aspherical lens 13 changes the profile of the laser beam. For example, the beam profile of a Gaussian shape is converted into a beam profile of a top-flat shape.

The laser beam transmitted through the aspherical lens 13 is collimated by the collimator lens 14 and is then incident on the mask 15. The mask 15 includes a transmission window and a shielding portion, and shapes the beam cross-section of the laser beam. The laser beam transmitted through the transmission window of the mask 15 is incident on the beam syringe 18 via the field lens 16 and the reflection mirror 17. [ The beam syringe 18 scans the laser beam in two dimensions. As the beam syringe 18, for example, a galvano scanner is used.

The laser beam scanned by the beam syringe 18 is condensed by the f? Lens 19 and is incident on the object 30 to be processed. The object to be processed 30 is supported on a stage 25. The field lens 16 and the f? Lens 19 image the transmission window of the mask 15 on the surface of the object 30 to be processed. The stage 25 moves the object 30 in a direction parallel to the surface thereof.

2 is a cross-sectional view of the laser oscillator 10 according to the first embodiment and a block diagram of the drive circuit. A blower 40, a pair of discharge electrodes 41, a heat exchanger 46, and a laser medium gas are accommodated in the chamber 50. A discharge space (42) is defined between the pair of discharge electrodes (41). As a discharge occurs in the discharge space 42, the laser medium gas is excited. In Fig. 2, a cross section orthogonal to the longitudinal direction of the discharge electrode 41 is shown. The blower 40 is, for example, a turbo blower. However, instead of the turbo blower, a cross flow fan, an axial flow fan, or the like may be used. 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 for returning from the blower 40 to the discharge space 42 between the discharge electrodes 41 and the blower 40 via the heat exchanger 46 is formed in the chamber 50. The heat exchanger (46) cools the laser medium gas that has become hot by the discharge.

A pair of terminals 51 are mounted on the wall surface of the chamber 50. The conductive member 43 of the discharge electrode 41 is connected to the terminal 51 by the chamber internal current path (current path) 52, respectively. The terminal 51 is connected to the drive circuit 11 by an external chamber current path 55.

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

At time t1, the trigger signal rises. The rise of the trigger signal corresponds to a laser oscillation start trigger. When the drive circuit 11 receives the laser oscillation start trigger at time t1, 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. After the high-frequency voltage is applied, when the discharge starts at time t2, the discharge current starts to flow.

After the start of the discharge, the optical output (laser pulse) rises at 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 when the delay time Td has elapsed from the time t1 at which the laser oscillation start trigger is given. The light output exhibits a sharp peak instantaneously at the time of rising, and then stabilizes. When the laser pulse rises, light is detected by the photodetector 22 (Fig. 1), and the detection signal is sent to the controller 20 (Fig. 1).

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

At time t4, the control device 20 gives the laser oscillation stop trigger to the laser light source 1 by lowering the trigger signal. When the drive circuit 11 receives the laser oscillation stop trigger from the control device 20, the drive circuit 11 stops applying the high-frequency voltage. When the high-frequency voltage is not applied to the discharge electrode 41, the discharge stops, the discharge current does not flow, and the light output becomes zero (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 for giving a laser oscillation start trigger to the time t4 for giving a laser oscillation stop trigger is referred to as a trigger time width Te.

Fig. 4 shows the relationship between the delay time Td and the pulse energy of the laser pulse when the control is performed under the condition that the trigger time width Te is constant. The abscissa represents the delay time (Td), and the ordinate represents the pulse energy. Since the trigger time width Te is constant, the sum of the delay time Td and the pulse width Pd (Fig. 3) becomes constant. As a result, if the delay time Td becomes longer, the pulse width Pd becomes shorter. As the pulse width Pd becomes shorter, the pulse energy decreases. When the laser oscillation is controlled so that the trigger time width Te becomes constant, it can be seen that the pulse energy becomes non-uniform due to the deviation of the delay time Td.

Next, a laser processing method using the laser processing apparatus according to the first embodiment will be described with reference to Figs. 5 and 6. Fig. The object to be processed 30 is positioned by first supporting the object 30 on the stage 25 (Fig. 1) and moving the stage 25 before laser processing. In the object to be processed 30, a plurality of processing points are defined within a range that can be scanned by the beam syringe 18. During the laser machining, the control device 20 controls the beam syringe 18 to punch the workpiece 30 by causing the laser pulses to be successively incident on the workpiece.

Fig. 5 shows a flowchart of processing executed by the control device 20 (Fig. 1) of the laser machining apparatus according to the first embodiment. FIG. 6 shows a timing chart of the trigger signal, the high-frequency voltage, the discharge current, and the optical output. The beam syringe 18 is controlled such that the object 30 is supported on the stage 25 and the laser pulse is incident on the processing point to be machined first when positioning of the object 30 is completed. In step S1, the process waits until the positioning of the beam syringe 18 is completed. When the positioning of the beam syringe 18 is completed, a laser oscillation start trigger is given to the laser light source 1 in step S2. Step S2 corresponds to the times t11, t21 and t31 shown in Fig.

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 time t12, t22, and t32 when the delay times Td1, Td2, and Td3 have elapsed from the times t11, t21, and t31 when the laser oscillation start trigger is applied. The delay times (Td1, Td2, and Td3) are not all the same due to the influence of the vibration of the reflector of the optical resonator and the impurities contained in the laser medium gas. In Fig. 6, the magnitude relation of the delay time is Td3 < Td1 < Td2.

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

In step S4, it is determined whether or not the delay time Td is within the specification. When the delay time Td is outside the specification, a laser oscillation stop trigger is given 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, the time t13 at which the laser oscillation stop trigger is given to the laser light source 1 with reference to the rise times t12, t22, t32 (Fig. 6) t23, and t33 (Fig. 6). Specifically, the times at which the time corresponding to the target pulse width Pd have elapsed from the rising times t12, t22 and t32 of the laser pulses are set as the times t13, t23, and t33, respectively, to which the laser oscillation stop trigger is given. The target pulse width Pd is stored in the control device 20 in advance.

In step S6, the laser oscillation stop trigger is given to the laser light source 1 at time t13, t23, and t33 (FIG. 6) calculated in step S5. As a result, the laser pulses Lp1, Lp2, and Lp3 fall.

In step S7 (Fig. 5), it is determined whether or not the machining is completed. When there remains a raw workpiece, the beam syringe 18 is controlled so that the laser pulse is incident on the workpiece to be machined next, and the process returns to step S1. When the machining of all the machining points has been completed, the laser machining process is terminated.

6, when the timing control is performed so that the trigger time widths Te1, Te2 and Te3 become equal to each other, the pulse width from the rising time to the falling time of the laser pulse becomes shorter than the delay times Td1, Td2 and Td3 ), And are thus uneven.

6) at which the laser oscillation stop trigger is given to the laser light source 1 with reference to the time t12, t22, t32 (Fig. 6) at which the laser pulse rises, Is determined. As a result, the pulse width Pd of the laser pulse is not influenced by the deviation of the delay times Td1, Td2, and Td3. Therefore, even if the delay times Td1, Td2, and Td3 are uneven, the pulse width Pd can be made constant. As a result, the non-uniformity of the pulse energy is reduced. If the elapsed time from the rising time t12, t22, t32 of the laser pulse to the time t13, t23, t33 at which the laser oscillation stop trigger is given 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 an arithmetic operation for determining the target pulse width after detecting the rise of the laser pulse. The method of performing the calculation for determining the pulse width of the laser pulse based on the measurement result after the rise of the laser pulse can not be applied to the laser processing using the laser pulse having the pulse width shorter than the calculation time. In the first embodiment, there is no need to perform an operation for determining the pulse width, so that the pulse width Pd is not limited by the calculation time. In the first embodiment, it is not necessary to measure the light energy or the like after the rise of the laser pulse, and only the presence or absence of the laser pulse may be detected. Therefore, there is no need to secure a measurement time for performing high-precision light energy measurement. For the reasons described above, the first embodiment can be applied to laser processing with a short pulse width Pd, for example, laser processing with a pulse width shorter than several tens of microseconds.

7 is a schematic view of a laser machining apparatus according to a second embodiment. The laser oscillator 10 receives power supply from the drive circuit 11 and emits a pulsed laser beam. For the laser oscillator 10, for example, a gas laser oscillator such as a carbon dioxide gas laser oscillator is used. The drive circuit 11 supplies and stops power to the laser oscillator 10 in synchronization with the trigger signal from the control device 20. [

The laser beam emitted from the laser oscillator 10 is transmitted through the spot position stabilizing optical system 12 and is incident on 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.

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. Fig. The control device 20 has a function block 20A for receiving a measurement value of a physical quantity of at least one of a current and a voltage supplied to the laser oscillator 10. [ The control device 20 stores condition data 20B for making the pulse energy constant. The function block 20C of the control device 20 for controlling the time to send out the oscillation stop trigger transmits the oscillation stop trigger based on the measurement value of the physical quantity and the condition data 20B for making the pulse energy constant Adjust the time.

The trigger generation function block 20D of the control device 20 sends the oscillation stop trigger to the drive circuit 11 at the time adjusted by the function block 20C for adjusting the time at which the oscillation stop trigger is transmitted. By adjusting the time at which the oscillation stop trigger is transmitted, the deviation of the pulse energy is suppressed, and the pulse energy is made uniform.

8 is a cross-sectional view of the laser oscillator 10 according to the second embodiment and a block diagram of the control system. The configuration of the inside of the chamber 50 and the configuration of the chamber external current path 55 is the same as the configuration of the inside of the chamber 50 and the chamber external current path 55 shown in Fig.

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

9 shows a trigger signal given to the drive circuit 11 (Fig. 7) from the control device 20 (Fig. 7), a high frequency voltage applied to the discharge electrode 41 A discharge current flowing, and a light output from the laser oscillator 10 (Fig. 7).

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

After the discharge is started, the optical output (laser pulse) rises at time t3 when the gain in the optical resonator of the laser oscillator 10 exceeds the loss. The light output exhibits a sharp peak instantaneously at the time of rising, and then stabilizes.

In the transient state immediately after the discharge is started, the amplitude of the discharge current is smaller than the amplitude at the steady state, and gradually increases with the lapse of time. After the light output rises at time t3, the discharge current becomes a steady state with an approximately constant amplitude.

At time t4, the trigger signal falls. The falling of the trigger signal corresponds 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 applying the high-frequency voltage. When the high-frequency voltage is not applied to the discharge electrode 41, the discharge stops, the discharge current does not flow, and the light output becomes zero (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 applied power. The pulse energy of the pulsed laser beam emitted from the laser oscillator is proportional to the excitation intensity under the condition that the pulse width is constant. Therefore, the pulse energy can be predicted from the applied electric power, that is, from 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 in Fig. 10A represents the peak value Ipp in the steady state, and the vertical axis represents the pulse energy. As the peak value Ipp of the discharge current becomes larger, the pulse energy also increases, and the relationship between them is almost linear.

Since the peak value Ipp of the discharge current is substantially constant after the discharge current becomes steady, by measuring the peak value Ipp of the discharge current from the start of discharge to a time before discharge stop, The pulse energy of the laser pulse can be predicted.

Fig. 10B shows the relationship between the high-frequency voltage application time (time from time t1 to time t4 in Fig. 9) under the condition that the peak value Ipp of the discharge current is constant and the pulse energy. The horizontal axis represents the high-frequency voltage application time, and the vertical axis represents the pulse energy. As the high-frequency voltage application time becomes longer, the pulse energy becomes larger, and the relationship between them becomes almost linear.

From the graphs shown in Figs. 10A and 10B, the following is derived. As the peak value Ipp of the discharge current becomes smaller, the pulse energy also becomes smaller. It is possible to keep the pulse energy constant by increasing the high-frequency voltage application time so as to compensate for the decrease in the pulse energy. From the graphs shown in Figs. 10A and 10B, it is possible to find the corresponding relationship between the peak value Ipp of the discharge current for maintaining the pulse energy constant and the high-frequency voltage application time.

11 shows a correspondence relationship between the peak value Ipp of the discharge current for keeping 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 high-frequency voltage application time becomes shorter. The corresponding relationship shown in Fig. 11 is stored in advance in the control device 20 (Fig. 7). This correspondence corresponds to the condition data 20B for making the pulse energy shown in Fig. 7 constant.

Next, a laser processing method using the laser processing apparatus according to the second embodiment will be described with reference to Figs. 12 and 13. Fig. The object to be processed 30 is positioned by first supporting the object 30 on the stage 25 (Fig. 7) and moving the stage 25 before laser processing. A plurality of processing points are defined in the object to be processed 30 within a range that can be scanned by the beam syringe 18. [ During the laser machining, the control device 20 controls the beam syringe 18 to punch the workpiece 30 by causing the laser pulses to be successively incident on the workpiece.

Fig. 12 shows a flowchart of processing executed by the control device 20 (Fig. 7) of the laser machining apparatus according to the second embodiment. 13 shows a timing chart of a trigger signal, a high-frequency voltage, a discharge current, and an optical output. The beam syringe 18 is controlled such that the object 30 is supported on the stage 25 and the laser pulse is incident on the processing point to be machined first when positioning of the object 30 is completed. In step S11, the process waits until the positioning of the beam syringe 18 is completed. When positioning of the beam syringe 18 is completed, an oscillation start trigger (instruction to start power supply) is given to the drive circuit 11 in step S12. Step S12 corresponds to the times t11, t21, and t31 shown in Fig.

The laser pulses Lp1, Lp2, and Lp3 rise after the application start time t11, t21, and t31 of the high-frequency voltage.

In step S13, the peak value Ipp of the discharge current is measured until a predetermined determination time Tj (FIG. 13) elapses. This measurement is performed by 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 占 퐏, and the determination time Tj is 5 占 퐏. When the frequency of the high-frequency voltage is 2 MHz, the determination time Tj of 5 mu s corresponds to the 10th cycle of the high-frequency voltage.

The measurement of the peak value Ipp of the discharge current starts after the discharge current becomes a normal state. When the discharge current becomes a steady state in about 3 cycles, the peak value Ipp from the 4th cycle to the 10th cycle is measured.

The peak values of the discharge current due to the oscillation start trigger at time t11, t21, and t31 shown in Fig. 13 are represented by Ipp1, Ipp2, and Ipp3, respectively. In the example shown in Fig. 13, the magnitude relation of the three peak values 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 value Ipp is within the specification, the time width from the oscillation start trigger to the oscillation stop trigger is calculated in step S15 based on the peak value Ipp. Hereinafter, an example of the processing in step S15 will be described. For example, an average of the plurality of peak values Ipp measured during the determination time Tj (FIG. 13) is obtained. From the average value of the peak value Ipp and the corresponding relationship shown in Fig. 11, the high-frequency voltage application time is obtained.

From the corresponding relationship shown in Fig. 11, the time widths Pd1, Pd2, and Pd3 are obtained for the peak values Ipp1, Ipp2, and Ipp3, respectively. The magnitude relation of the time width is Pd3 < Pd1 < Pd2.

In step S16 (FIG. 12), the oscillation stop trigger (command of power supply stop) is transmitted from the oscillation start trigger at a time point when the time width obtained in step S15 has elapsed. In Fig. 13, an oscillation stop trigger is transmitted at time t12, t22, and t32. The time width from time t11 to t12 is equal to Pd1, the time width from time t21 to t22 is equal to Pd2, and the time width from time t31 to time t32 is equal to Pd3. At time t12, t22, and t32, the discharge stops and laser pulses Lp1, Lp2, and Lp3 fall, respectively.

In step S17 (Fig. 12), it is determined whether or not the machining has been completed. When there remains a raw workpiece, the beam syringe 18 is controlled so that the laser pulse is incident on the workpiece to be machined next, and the process returns to step S11. When the machining of all the machining points has been completed, the laser machining process is terminated.

The optical output of the laser pulse Lp2 in the steady state is lower than the optical 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 decrease in the optical output is compensated. The optical output of the laser pulse Lp3 in the steady state is higher than the optical output of the laser pulse Lp1. By making the pulse width of the laser pulse Lp3 shorter than the pulse width of the laser pulse Lp1, the increment of the optical output is compensated. The pulse widths of the laser pulses Lp1, Lp2, and Lp3 can be made uniform since the time width from the oscillation start trigger to the oscillation stop trigger is determined based on the corresponding relationship shown in Fig.

As 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, so that the pulse energy of the laser pulse can be made closer to uniformity.

The peak value Ipp of the discharge current can be measured easily in a shorter time than the optical output. Thus, the method according to the second embodiment can shorten the determination time Tj (Fig. 13) as compared with the case where the optical output is measured to adjust the pulse width. As a result, the method according to the second embodiment can be applied even if the pulse width of the laser pulse to be emitted is 100 mu s or less.

Although the peak value Ipp of the discharge current is measured during the determination time Tj in the second embodiment, another physical quantity depending on the electric power supplied to the discharge electrode 41 (FIG. 8) may be measured. For example, the effective value of the discharge current may be measured.

When the discharge state changes, the voltage applied between the pair of discharge electrodes 41 also changes. The change of the voltage and the change of the electric power supplied to the discharge electrode 41 are followed. Therefore, the peak value or the effective value of the voltage applied between the discharge electrodes 41 may be employed as another physical quantity depending on the electric power supplied to the discharge electrode 41 (Fig. 8). In this way, the physical quantity of at least one of the voltage or the electric current applied to the discharge electrode 41 can be measured.

Although the present invention has been described with reference to the above embodiments, the present invention is not limited thereto. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like are possible.

1 laser light source
10 laser oscillator
11 drive circuit
12 spot position stabilization optical system
13 aspheric lens
14 Collimate Lens
15 Mask
16-field lens
17 reflection mirror
18 beam syringe
19 f? Lens
20 control device
20A Function block for receiving measured values of physical quantities
20B Condition data that makes the pulse energy constant
20C Function block for performing time adjustment to send oscillation stop trigger
20D trigger generation function block
21 partial reflector
22 photodetector
25 stages
30 object to be processed
40 blowers
41 discharge electrode
42 discharge space
43 conductive member
44 ceramic member
46 Heat exchanger
50 chamber
51 terminal
52 With chamber internal current
55 chamber external current
56 detector

Claims (11)

A laser light source that starts laser oscillation in synchronization with an oscillation start trigger received from the outside and stops laser oscillation in synchronization with the oscillation stop trigger,
A detector for detecting a physical quantity depending on at least one of a power given to the laser light source and a laser pulse emitted from the laser light source;
And a control device for giving the oscillation start trigger to the laser light source and for giving the oscillation stop trigger to the laser light source in the laser pulse emitted from the laser light source based on the detection result of the physical quantity by the detector
Lt; / RTI &
The detector detects laser pulses emitted from the laser light source,
Wherein the control device determines the time to give the oscillation stop trigger to the laser light source based on the detection time of the laser pulse by the detector and gives the oscillation stop trigger to the laser light source at the determined time,
Wherein the control device stores the target pulse width of a laser pulse to be emitted, and when the same time as the target pulse width has elapsed from the detection time of the laser pulse by the detector, A laser processing apparatus for imparting a trigger. delete delete The method according to claim 1,
Wherein the laser light source
Laser medium gas,
A discharge electrode for exciting the laser medium gas,
And a drive circuit for starting supply of electric power to the discharge electrode by receiving the oscillation start trigger and stopping supply of electric power to the discharge electrode by receiving the oscillation stop trigger,
Lt; / RTI &
Wherein the physical quantity is at least one of a voltage and a current applied to the discharge electrode,
Wherein the control device gives the oscillation stop trigger to the drive circuit based on the detection value of the physical quantity detected by the detector after giving the oscillation start trigger to the drive circuit. 5. The method of claim 4,
Wherein the control device controls the oscillation start trigger after giving the oscillation start trigger based on the detection result detected by the detector until a predetermined determination time elapses after giving the oscillation start trigger to the drive circuit And calculates a time width until the laser beam is applied. A laser light source that starts laser oscillation in synchronization with an oscillation start trigger received from the outside and stops laser oscillation in synchronization with the oscillation stop trigger,
A detector for detecting a physical quantity depending on at least one of a power given to the laser light source and a laser pulse emitted from the laser light source;
And a control device for giving the oscillation start trigger to the laser light source and for giving the oscillation stop trigger to the laser light source in the laser pulse emitted from the laser light source based on the detection result of the physical quantity by the detector
Lt; / RTI &
Wherein the laser light source
Laser medium gas,
A discharge electrode for exciting the laser medium gas,
And a drive circuit for starting supply of electric power to the discharge electrode by receiving the oscillation start trigger and stopping supply of electric power to the discharge electrode by receiving the oscillation stop trigger,
Lt; / RTI &
Wherein the physical quantity is at least one of a voltage and a current applied to the discharge electrode,
The control device gives the oscillation stop trigger to the drive circuit based on the detection value of the physical quantity detected by the detector after giving the oscillation start trigger to the drive circuit,
Wherein the control device reduces the time width from the oscillation start trigger to the oscillation stop trigger as the physical quantity detected by the detector is larger. A laser light source that starts laser oscillation in synchronization with an oscillation start trigger received from the outside and stops laser oscillation in synchronization with the oscillation stop trigger,
A detector for detecting a physical quantity depending on at least one of a power given to the laser light source and a laser pulse emitted from the laser light source;
And a control device for giving the oscillation start trigger to the laser light source and for giving the oscillation stop trigger to the laser light source in the laser pulse emitted from the laser light source based on the detection result of the physical quantity by the detector
Lt; / RTI &
Wherein the laser light source
Laser medium gas,
A discharge electrode for exciting the laser medium gas,
And a drive circuit for starting supply of electric power to the discharge electrode by receiving the oscillation start trigger and stopping supply of electric power to the discharge electrode by receiving the oscillation stop trigger,
Lt; / RTI &
Wherein the physical quantity is at least one of a voltage and a current applied to the discharge electrode,
The control device gives the oscillation stop trigger to the drive circuit based on the detection value of the physical quantity detected by the detector after giving the oscillation start trigger to the drive circuit,
The control device stores a correspondence relationship between the physical quantity measured by the detector and the time from the oscillation start trigger to the oscillation stop trigger,
And obtains a time width from the oscillation start trigger to the oscillation stop trigger based on the detected value of the physical quantity detected by the detector and the corresponding relationship. A step of giving the oscillation start trigger to a laser light source that starts laser oscillation in synchronization with an oscillation start trigger received from the outside and stops laser oscillation in synchronization with the oscillation stop trigger;
A step of detecting a physical quantity depending on at least one of an electric power given to the laser light source and a laser pulse emitted from the laser light source;
A step of giving the oscillation stop trigger to the laser light source in the laser pulse emitted from the laser light source based on the detection result of the physical quantity
To have,
Detecting a rise time of the laser pulse emitted from the laser light source,
And a laser processing method for giving the oscillation stop trigger to the laser light source at a time when a time corresponding to a preset target pulse width has elapsed since the rise time of the laser pulse in the step of giving the oscillation stop trigger . delete 9. The method of claim 8,
Wherein the laser light source includes a discharge electrode,
Wherein the physical quantity detected in the step of detecting the physical quantity is at least one of a voltage or a current given to the discharge electrode,
Wherein the step of imparting the oscillation-
Calculating a time width for supplying electric power to the discharge electrode based on the detection value of the physical quantity;
A step of giving the oscillation stop trigger to the laser light source at a time point when the calculated time width has elapsed from the time when the oscillation start trigger is given
. 11. The method of claim 10,
Wherein the time width is calculated based on a detection value of the voltage or current from a time point at which the oscillation start trigger is given until a predetermined determination time elapses in the step of calculating the time width.

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