KR20200111614A - Laser control apparatus and Laser pulse output apparatus - Google Patents

Abstract

Provided is a laser control apparatus capable of reducing variations in intensity of laser pulses. According to the present invention, the laser control apparatus is synchronized with timing of rising of the laser pulse output from a laser oscillator. Therefore, start of cutting is instructed to a cutting optical system which cuts a part from the laser pulse output from the laser oscillator.

Description

Laser control apparatus and laser pulse output apparatus

This application claims priority based on Japanese Patent Application No. 2019-051470 filed on March 19, 2019. The entire contents of the application are incorporated by reference in this specification.

The present invention relates to a laser control device and a pulse laser output device.

A technique for performing punching processing on a printed substrate using a pulsed laser beam is known (Patent Document 1). In the laser processing apparatus disclosed in the following patent document 1, the elapsed time from the time of the laser oscillation command to the point at which the energy of the laser pulse reaches a predetermined intensity is measured for a plurality of laser oscillation commands, and the average value is obtained. . The acoustic-optical modulator is controlled so as to start the branching (cutting of the laser pulse) in the direction to use the laser pulse for processing after a period of time after the laser oscillation command time has been added to the average value.

Patent Document 1: Japanese Laid-Open Patent Publication No. 2018-99692

After giving the command to start oscillation to the laser oscillator, the time until the laser pulse is output (the laser pulse rises) varies for each laser pulse. Further, in general, the intensity of the laser pulse is not constant from the point when the laser pulse rises, but fluctuates with the passage of time. If cutting of the laser pulse is started when a certain time has elapsed from the command point of start of oscillation, the elapsed time from the point of rising of the laser pulse to the starting point of cutting will vary. As a result, the intensity of the cut out laser pulses varies among the laser pulses.

An object of the present invention is to provide a laser control device and a pulse laser output device capable of reducing variations in the intensity of laser pulses.

According to one aspect of the present invention,

A laser control device for instructing to start cutting is provided to a cutting optical system that cuts a part from the laser pulse output from the laser oscillator in synchronization with the timing of rising of the laser pulse output from the laser oscillator.

According to another aspect of the present invention,

A laser oscillator that outputs a pulsed laser beam,

A sensor for detecting the light intensity of the pulsed laser beam output from the laser oscillator,

A cutting optical system that cuts a part from the laser pulse of the pulsed laser beam output from the laser oscillator,

A pulse laser output device having a control device for acquiring the detection result from the sensor, detecting the rising point of the laser pulse, synchronizing with the timing of the rising of the laser pulse, and instructing the cutting optical system to start cutting the laser pulse is provided. do.

Since a part of the laser pulse is cut in synchronization with the timing of the rise of the laser pulse, variations in the intensity of the cut laser pulse can be reduced.

1 is a schematic diagram of a pulse laser output device according to an embodiment.
2 is a graph showing waveforms of a trigger signal trg, a laser pulse LP1, a cutting signal chp, and a laser pulse LP2 of the pulse laser output device according to the embodiment.
3 is a graph showing waveforms of a trigger signal trg, a laser pulse LP1, a cutting signal chp, and a laser pulse LP2 of a pulse laser output device according to a comparative example.
4 is a schematic diagram of a pulse laser output device according to another embodiment.
5 is a graph showing waveforms of a trigger signal trg, a laser pulse LP1, a cutting signal chp, and a laser pulse LP2 of a pulse laser output device according to another embodiment.

A pulse laser output device according to an embodiment will be described with reference to FIGS. 1 and 2.

1 is a schematic diagram of a pulse laser output device according to an embodiment. The pulse laser output device according to the embodiment is used, for example, for punching a printed board.

The laser oscillator 10 outputs a pulsed laser beam based on a command from the control device 40. As the laser oscillator 10, for example, a gas laser oscillator such as a carbon dioxide laser oscillator is used. The pulsed laser beam output from the laser oscillator 10 is branched into two paths in the beam splitter 11. As the beam splitter 11, for example, a partial reflection mirror is used.

One of the two pulsed laser beams branched from the beam splitter 11 enters the cutting optical system 14 via the irradiation optical system 12 and the aperture 13, and the other enters the sensor 20. The irradiation optical system 12 changes at least one of the diffusion angle and the beam diameter of the pulsed laser beam. As the irradiation optical system 12, for example, a beam expander is used. The aperture 13 shapes the beam cross section of the pulsed laser beam.

The cutting optical system 14 cuts a part on the time axis from the incident laser pulse LP1, and generates a laser pulse LP2 used for processing. A portion of the laser pulse LP1 other than the laser pulse LP2 enters the beam damper 15, and the cut laser pulse LP2 propagates along the processing path. As the cutting optical system 14, for example, an acoustic optical modulator (AOM) is used.

The laser pulse LP2 cut out from the laser pulse LP1 enters the object 50 to be processed through the fold mirror 16, the scanning optical system 17, and the lens 19. The scanning optical system 17 changes the traveling direction of the pulsed laser beam to a two-dimensional direction. As the scanning optical system 17, for example, a galvano scanner including a pair of movable mirrors 18X and 18Y is used. The lens 19 condenses the pulsed laser beam whose traveling direction is changed in the scanning optical system 17 onto the surface of the object 50. As the lens 19, an f? lens, for example, is used. By operating the scanning optical system 17, a pulsed laser beam can be made to be incident at an arbitrary position within a partial area (scan area) of the surface of the object 50.

The object to be processed 50 is, for example, a printed board, and is held horizontally on the stage 30. The moving mechanism 31 moves the stage 30 in two directions parallel to the horizontal plane and perpendicular to each other. By moving the stage 30, an arbitrary area within the surface of the object 50 can be placed in a scan area that can be scanned by the scanning optical system 17.

The sensor 20 detects the light intensity of the incident pulsed laser beam, and outputs an electric signal according to the light intensity. As the sensor 20, for example, a photovoltaic device capable of high-speed response is used. The electric signal output from the sensor 20 is input to the control device 40.

The control device 40 outputs a trigger signal trg for instructing the laser oscillator 10 to start and end the output of the laser pulse. Further, the control device 40 outputs a cutting signal chp for instructing the cutting optical system 14 to start and end cutting of the laser pulse LP2. Further, the control device 40 controls the operation of the scanning optical system 17 and the moving mechanism 31.

Various parameters defining laser output conditions are input to the input device 41. As the input device 41, for example, a keyboard, a touch panel, a pointing device, a communication device, a removable media reading device, and the like are used. Values of various parameters input to the input device 41 are input to the control device 40.

Fig. 2 is a graph showing waveforms of trigger signal trg, laser pulse LP1, cutting signal chp, and laser pulse LP2. 2 shows a period in which two laser pulses LP1 are output.

The rising of the trigger signal trg corresponds to the command to start the output of the laser pulse, and the falling corresponds to the command to stop the output of the laser pulse. The rising of the cutting signal chp corresponds to the command to start cutting from the laser pulse LP1, and the fall corresponds to the command to end cutting from the laser pulse LP1.

When the control device 40 (FIG. 1) raises the trigger signal trg to command the laser oscillator 10 (FIG. 1) to start outputting the laser pulse LP1, the delay time td11 starts from the rising point t11 of the trigger signal trg. At the elapsed time t12, the output of the laser pulse LP1 starts (laser pulse LP1 rises). When the control device 40 descends the trigger signal trg to command the stop of the output of the laser pulse LP1, the laser pulse LP1 falls from the falling time t15 of the trigger signal trg (the waveform of the laser pulse LP1 falls). The elapsed time from the rising point t11 of the trigger signal trg to the falling point t15 is previously input from the input device 41 (Fig. 1) and stored in the control device 40.

The waveform of the laser pulse LP1 depends on the characteristics of the laser oscillator 10 (Fig. 1), and the period from the rising point t12 of the laser pulse LP1 to the falling point t15, and the light intensity of the laser pulse LP1 fluctuates with time. do. For example, at the rising point t12 of the laser pulse LP1, the waveform rapidly rises to form a sharp peak, and then the light intensity continues for a substantially constant period, and then the light intensity gradually decreases. In addition, there is also a laser oscillator having a characteristic of outputting a laser pulse in which the light intensity gradually increases from the rising point t12 of the laser pulse LP1, and then the light intensity continues for a substantially constant period.

The control device 40 acquires the detection result of the light intensity of the laser pulse LP1 from the sensor 20 and detects an increase in the laser pulse LP1. For example, the point in time when the light intensity of the laser pulse LP1 reaches a predetermined threshold is determined as the rising point t12 of the laser pulse LP1. This threshold may be set based on, for example, the maximum value of the peak appearing immediately after the rise of the laser pulse, the average value of the light intensity during a period in which the light intensity is substantially constant. As an example, the threshold may be set to 10% of the maximum value of the peak. The control device 40 starts cutting the laser pulse LP2 by raising the cutting signal chp to the cutting optical system 14 (Fig. 1) at a time t13 after a certain waiting time tw11 has elapsed from the rising point t12 of the laser pulse LP1. Command. The value of the constant waiting time tw11 is input from the input device 41 (Fig. 1) in advance and is stored in the control device 40.

The control device 40 lowers the cutting signal chp by lowering the cutting signal chp at a time t14 at which a time corresponding to a predetermined pulse width has elapsed from the time t13 at which the cutting optical system 14 is commanded to start cutting the laser pulse LP2. For (14), the end of cutting of the laser pulse LP2 is commanded. During the period from the rising point t13 of the cutting signal chp to the falling point t14, the laser pulse LP2 is cut out from the laser pulse LP1.

The period from the time point t13 in which the cutting start is commanded to the time point t14 in which the cutting end is commanded is set, for example, within a period in which the light intensity of the laser pulse LP1 changes substantially constant.

The delay time td21 from the rising point t21 of the trigger signal trg commanding the start of the output of the second shot laser pulse LP1 to the rising point t22 of the laser pulse LP1 is not limited to the same as the delay time td11 of the first shot laser pulse LP1. . The control device 40 raises the cutting signal chp to the cutting optical system 14 by raising the cutting signal chp at the time t23 at which a certain waiting time tw21 has elapsed from the time t22 when the output start of the laser pulse LP1 of the second shot is detected. Command to start cutting. The waiting time tw21 of the second shot is the same as the waiting time tw11 of the first shot.

The elapsed time from the time point t23 in which the cutting start is commanded to the time point t24 to designate the cutting end is the same as the elapsed time from the time point t13 in which the cutting start is commanded in the first shot to the time point t14 in which the cutting end is commanded. The elapsed time from the rising point t21 of the trigger signal trg to the falling point t25 of the trigger signal trg is the same as the elapsed time from the rising point t11 of the trigger signal trg to the falling point t15 in the first shot.

Next, the excellent effect of the above example will be described while comparing with the comparative example shown in FIG. 3.

3 is a graph showing waveforms of a trigger signal trg, a laser pulse LP1, a cutting signal chp, and a laser pulse LP2 in a pulse laser output device according to a comparative example. The timing and waveform of the trigger signal trg and the laser pulse LP1 are the same as in the case of the embodiment shown in FIG.

In the comparative example, the start of cutting is commanded by raising the cutting signal chp at the time t13 after the constant waiting time tw31 has elapsed from the rising time t11 of the trigger signal trg. In the same manner for the second shot, the start of cutting is commanded by raising the cutting signal chp from the rising point t21 of the trigger signal trg commanding the start of the output of the laser pulse LP1 to the point t23 when a certain waiting time tw41 has elapsed. The waiting time tw41 in the second shot is the same as the waiting time tw31 in the first shot.

In the first shot, the period from the time point t13 in which the start of cutting is commanded to the time point t14 in which the end of cutting is commanded is in a period in which the light intensity of the laser pulse LP1 changes substantially constant. By the way, in the second shot, since the delay time td21 is longer than the delay time td11 of the first shot, the time point t23 that commands the start of cutting is located within the peak immediately after the rise of the laser pulse LP1. For this reason, the waveform of the laser pulse LP2 of the second shot is greatly different from the waveform of the laser pulse LP2 of the first shot. As a result, the pulse energy (energy per pulse) of the laser pulse LP2 of the second shot is different from that of the laser pulse LP2 of the first shot. This is despite the deviation of the delay times td11 and td21 from the rising points t11 and t21 of the trigger signal trg commanding the start of the output of the laser pulse LP1 to the actual rising points t12 and t22 of the laser pulse LP1, the trigger signal trg This is because the command to start cutting is given in synchronization with the timing of the ascent.

In contrast, in the above embodiment, in synchronization with the actual rising points t12 and t22 of the laser pulse LP1, the control device 40 gives the cutting optical system 14 a command to start cutting. Therefore, without being affected by the deviation of the delay times td11 and td21 from the rising points t11 and t21 of the trigger signal trg to the actual rising points t12 and t22 of the laser pulse LP1, the waveform of the laser pulse LP1 is Pulse LP2 can be cut. Thereby, it is possible to suppress variations in the pulse energy of the laser pulse LP2.

Next, preferable lengths of the waiting times tw11 and tw21 (Fig. 2) will be described. If the waiting times tw11 and tw21 are excessively shortened, the leading portion of the laser pulse LP2 is caught in a part of the peak immediately after the rise of the laser pulse LP1. When the head of the laser pulse LP2 is caught on a part of the peak of the laser pulse LP1, a slight change in the waveform of the laser pulse LP1, for example, a slight change in the peak width, greatly fluctuates the pulse energy of the laser pulse LP2. In order to suppress variations in the pulse energy of the laser pulse LP2 due to the change in the waveform of the laser pulse LP1, the waiting times tw11 and tw21 are preferably made longer than the time width of the peak immediately after the rise of the laser pulse LP1.

Even in a period in which the light intensity of the laser pulse LP1 changes substantially constant, the light intensity gradually changes according to the characteristics of the laser oscillator 10. The waiting times tw11 and tw21 may be set so that the laser pulse LP2 is cut out from the part where the time change of the light intensity of the laser pulse LP1 is as small as possible. By setting the waiting times tw11 and tw21 in this way, even if the waveform of the laser pulse LP1 changes slightly, the fluctuation of the pulse energy of the laser pulse LP2 becomes difficult to occur.

Therefore, the waiting times tw11 and tw21 (FIG. 2) in the pulse laser output device according to the above embodiment observe the waveform of the actual laser pulse LP1, and the laser pulse LP2 becomes from a period in which the light intensity is maintained substantially constant. Just set it to cut off In the above embodiment, when the laser pulse LP1 shows other waveforms, for example, it is possible to apply even when the light intensity gradually increases from the output start point and becomes substantially constant thereafter.

Next, a modified example of the above embodiment will be described.

In the above embodiment, a pulse laser output device is used for punching a printed board. In addition, the pulsed laser output device according to the embodiment can be used for performing laser processing using a laser pulse obtained by cutting a part of a laser pulse output from a laser oscillator.

Next, a pulse laser output device according to another embodiment will be described with reference to FIGS. 4 and 5. Hereinafter, a description of the configuration common to the pulse laser output device shown in FIGS. 1 and 2 will be omitted.

4 is a schematic diagram of a pulse laser output device according to this embodiment. In the embodiment shown in Fig. 1, the cutting optical system 14 cuts out one laser pulse LP2 from the laser pulse LP1, and propagates it along one processing path. In contrast, in the pulse laser output device shown in Fig. 4, the cutting optical system 14 cuts out two laser pulses LP2 and LP3 from the laser pulse LP1, and propagates the laser pulses LP2 and LP3 along different processing paths.

In the processing path through which the laser pulses LP2 and LP3 are propagated, the fold mirror 16, the scanning optical system 17, the lens 19, the stage 30, and the processing path of the pulse laser output device shown in FIG. And a moving mechanism 31 is disposed. By using the laser pulses LP2 and LP3, it is possible to simultaneously process two objects 50 to be processed.

Fig. 5 is a graph showing waveforms of a trigger signal trg, a laser pulse LP1, a cutting signal chp, and a laser pulse LP2 and LP3. 5 shows a period in which one laser pulse LP1 is output.

The waveform and output timing of the trigger signal trg and the laser pulse LP1 are the same as in the case of the embodiment shown in FIG. When the control device 40 detects the rise of the laser pulse LP1, the cutting signal chp to the cutting optical system 14 (Fig. 4) is raised at a time t13 at which a certain waiting time tw11 has elapsed from the rising time t12 of the laser pulse LP1. By doing so, the start of cutting of the laser pulse LP2 is commanded. A laser pulse to the cutting optical system 14 by lowering the cutting signal chp at a time t14 at which a time corresponding to a predetermined pulse width has elapsed from the time t13 in which the cutting start of the laser pulse LP2 is commanded to the cutting optical system 14. Commands the end of cutting of LP2.

In addition, the control device 40 increases the cutting signal chp to the cutting optical system 14 (Fig. 4) at a time t16 after a certain waiting time tw12 has elapsed from the rising time t12 of the laser pulse LP1. Command start. The waiting time tw12 is longer than the sum of the waiting time tw11 and the pulse widths t14-t13. The command to start cutting of the laser pulse LP2 and the command to start cutting of the laser pulse LP3 are distinguished by changing the size of the cutting signal chp, for example, a voltage value. A laser pulse to the cutting optical system 14 by lowering the cutting signal chp at a time t17 at which a time corresponding to a predetermined pulse width has elapsed from the time t16 that commanded the cutting optical system 14 to start cutting the laser pulse LP3. Instructs the end of LP3 cutting.

The period from the time point t13 in which the cutting start of the laser pulse LP2 is commanded to the time point t17 in which the cutting end of the laser pulse LP3 is commanded is set within a period in which the light intensity of the laser pulse LP1 changes substantially constant.

Next, excellent effects of the embodiment shown in FIGS. 4 and 5 will be described.

Also in this embodiment, since the command to start cutting of the laser pulses LP2 and LP3 is given in synchronization with the rising point t12 of the laser pulse LP1, the delay time from the rising point t11 of the trigger signal trg to the rising point t12 of the laser pulse LP1 Even if there is a deviation in td11, the laser pulses LP2 and LP3 can be cut out from the period in which the light intensity of the laser pulse LP1 is maintained substantially constant.

In addition, in the present embodiment, it is possible to simultaneously process two workpieces 50 in two machining paths. Thereby, the processing power of laser processing is improved.

Next, a modified example of this embodiment will be described. In the present embodiment, the waiting time tw12 until the command to start cutting of the laser pulse LP3 is given as the elapsed time from the rising point t12 of the laser pulse LP1, but the cutting signal chp corresponding to the laser pulse LP2 is lowered. It may be designated as the elapsed time from the time point t14. In this case as well, since the values of the waiting time tw11 and the pulse width of the laser pulse LP2 are set in advance, it can be said that the timing for giving the command to start cutting of the laser pulse LP3 is synchronized with the timing of the rising of the laser pulse LP1. .

Each of the above-described embodiments is an example, and it goes without saying that partial substitutions or combinations of configurations shown in other embodiments are possible. The same operation and effect by the same configuration of a plurality of embodiments are not sequentially mentioned for each embodiment. In addition, the present invention is not limited to the above-described embodiments. For example, it will be apparent to those skilled in the art that various changes, improvements, combinations, and the like are possible.

10 Laser oscillator
11 Beam splitter
12 Irradiation optical system
13 aperture
14 cutting optical system
15 beam damper
16 fold mirror
17 Scanning optical system
18X, 18Y movable mirror
19 lens
20 sensors
30 stage
31 Moving Mechanism
40 control unit
41 Input device
50 Object to be processed

Claims (6)

A laser control device for instructing a cutting optical system to start cutting in synchronization with a timing of rising of the laser pulse output from the laser oscillator and cut a part from the laser pulse output from the laser oscillator. The method of claim 1,
Further, a laser control device for instructing the cutting optical system to end cutting. The method according to claim 1 or 2,
In addition, the value of the waiting time from the rising point of the laser pulse to the point of commanding the start of cutting of the laser pulse is obtained, and the time corresponding to the obtained waiting time value has elapsed from the point of detecting the rise of the laser pulse. At this point, the laser control device instructs the cutting optical system to start cutting the laser pulse. A laser oscillator that outputs a pulsed laser beam,
A sensor for detecting the light intensity of the pulsed laser beam output from the laser oscillator,
A cutting optical system that cuts a part from the laser pulse of the pulsed laser beam output from the laser oscillator,
A pulse laser output device having a control device for acquiring a detection result from the sensor, detecting a rising point of the laser pulse, synchronizing with the timing of the rising of the laser pulse, and instructing the cutting optical system to start cutting the laser pulse. The method of claim 4,
The control device stores the value of the pulse width of the laser pulse to be cut, and a time corresponding to the pulse width of the laser pulse to be cut has elapsed after instructing the cutting optical system to start cutting the laser pulse. At this point, a pulse laser output device that instructs the cutting optical system to end cutting. The method according to claim 4 or 5,
In addition, it has an input device for inputting a value of the waiting time from the rising point of the laser pulse to the point of commanding the start of cutting of the laser pulse,
The control device instructs the cutting optical system to start cutting the laser pulse when a time corresponding to the obtained waiting time value has elapsed from the time when the rise of the laser pulse is detected.

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