TW202035049A - Laser control apparatus and pulsed laser outputting apparatus capable of reducing the intensity deviation of laser pulses cut from an laser oscillator - Google Patents

Abstract

The present invention provides a laser control apparatus that is capable of reducing the intensity deviation of laser pulses. The laser control apparatus synchronously instructs a cutting optical system to start cutting at the time while the output of the laser pulses from the laser oscillator rises, and to cut a part out of the laser pulses outputting from the laser oscillator.

Description

Laser control device and pulse laser output device

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

There is known a technique for drilling a printed circuit board using a pulsed laser beam (Patent Document 1). In the laser processing device disclosed in Patent Document 1 below, for a plurality of laser oscillation commands, the elapsed time from the point of the laser oscillation command to the point when the energy of the laser pulse reaches a predetermined intensity is measured to determine the average value. The acousto-optic modulator is controlled as follows: after the time of the laser oscillation command is added a constant time to the average value, the laser pulse starts to be branched in the direction to be used in the processing (cut out the mine Radio pulse). (Prior technical literature) (Patent Document)

Patent Document 1: Japanese Patent Application Publication No. 2018-99692

(Problems to be solved by the present invention)

The time from when the instruction to start oscillation is given to the laser oscillator to when the laser pulse is output (laser pulse rise) will vary for each laser pulse. In addition, generally, the intensity of the laser pulse is not constant from the point when the laser pulse rises, and fluctuates over time. If the cutting out of the laser pulse is started when a constant time has elapsed from the start of the oscillation command, the elapsed time from the rising time of the laser pulse to the starting time of cutting out will vary. As a result, the intensity of the laser pulses that are cut out will vary between the laser pulses.

The object of the present invention is to provide a laser control device and a pulse laser output device that can reduce the intensity deviation of the laser pulse. (Means to solve the problem)

According to a viewpoint of the present invention, Provided is a laser control device, which, in synchronization with the rising time of the laser pulse output from the laser oscillator, orders the cutting-out optical system to start cutting out a part of the laser pulse output from the aforementioned laser oscillator .

According to another viewpoint of the present invention, A pulse laser output device is provided, which has: Laser oscillator, output pulse laser beam; The sensor detects the light intensity of the pulsed laser beam output from the aforementioned laser oscillator; Cut out the optical system to cut out a part of the laser pulse output from the pulsed laser beam of the aforementioned laser oscillator; and The control device obtains the detection result from the sensor to detect the rising time of the laser pulse, and in synchronization with the rising time of the laser pulse, orders the cutting-out optical system to start cutting out the laser pulse. (Effect of Invention)

Since a part of the laser pulse is cut out in synchronization with the rising time of the laser pulse, the intensity deviation of the cut laser pulse can be reduced.

1 and 2, the pulse laser output device based on the embodiment will be described. Fig. 1 is a schematic diagram of a pulse laser output device based on the embodiment. The pulse laser output device based on the embodiment is used, for example, in the drilling of printed circuit boards.

The laser oscillator 10 outputs a pulsed laser beam in accordance with instructions 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 split into two paths by 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 by the beam splitter 11 enters the cut-out optical system 14 through the illumination 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 divergence 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-out optical system 14 cuts out a part of the time axis from the incident laser pulse LP1, and generates the laser pulse LP2 to be used in processing. In the laser pulse LP1, the part other than the laser pulse LP2 is incident on the beam damper 15, and the cut laser pulse LP2 propagates along the processing path. As the cut-out optical system 14, for example, an acousto-optic modulator (AOM) is used.

The laser pulse LP2 cut out from the laser pulse LP1 enters the object 50 to be processed via the folding mirror 16, the scanning optical system 17 and the lens 19. The scanning optical system 17 swings the traveling direction of the pulsed laser beam in a two-dimensional direction. As the scanning optical system 17, for example, a Galvo scanner including a pair of movable mirrors 18X and 18Y is used. The lens 19 focuses the pulsed laser beam whose traveling direction is oscillated by the scanning optical system 17 on the surface of the object 50 to be processed. As the lens 19, for example, an fθ lens is used. By operating the scanning optical system 17, the pulsed laser beam can be incident on an arbitrary position within a partial area (scanning area) of the surface of the object 50.

The object 50 to be processed is, for example, a printed circuit board, and is held horizontally on the stage 30. The moving mechanism 31 moves the stage 30 in two directions that are parallel to the horizontal plane and orthogonal to each other. By moving the stage 30, an arbitrary area in the surface of the object 50 to be processed can be arranged in a scanning 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 electrical signal corresponding to the light intensity. As the sensor 20, for example, a photoelectric element capable of high-speed response is used. The electrical signal output from the sensor 20 is input into the control device 40.

The control device 40 outputs a trigger signal trg, and the trigger signal trg orders the laser oscillator 10 to start and end the output of the laser pulse. In addition, the control device 40 outputs a cut-out signal chp, which instructs the cut-out optical system 14 to start and end the cut-out of the laser pulse LP2. In addition, the control device 40 controls the operations of the scanning optical system 17 and the movement mechanism 31.

Various parameters that specify laser output conditions are input into the input device 41. As the input device 41, for example, a keyboard, a touch panel, a pointing device, a communication device, and a reading device for removable media are used. Various parameter values input into the input device 41 are input into the control device 40.

FIG. 2 is a chart showing the waveforms of the trigger signal trg, the laser pulse LP1, the cut-out signal chp, and the laser pulse LP2. Figure 2 shows the output period of two laser pulses LP1.

The rise of the trigger signal trg is equivalent to a command to start the laser pulse output, and the fall is equivalent to a command to stop the laser pulse output. The rise of the cut-out signal chp corresponds to a command from the laser pulse LP1 to start the cut-out, and the drop corresponds to a command from the laser pulse LP1 to end the cut-out.

If the control device 40 (FIG. 1) instructs the laser oscillator 10 (FIG. 1) to start outputting the laser pulse LP1 by raising the trigger signal trg, only the delay time td11 has elapsed from the rising time point t11 of the trigger signal trg At the time point t12, laser pulse LP1 is output (laser pulse LP1 rises). If the control device 40 orders the stop of the output of the laser pulse LP1 by causing the trigger signal trg to fall, the laser pulse LP1 falls from the falling time point t15 of the trigger signal trg (the waveform of the laser pulse LP1 falls). The elapsed time from the rising time point t11 of the trigger signal trg to the falling time 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 (Figure 1). During the period from the rising time point t12 of the laser pulse LP1 to the falling time point t15, the light intensity of the laser pulse LP1 coincides with the passage of time Changes. For example, after the waveform rises sharply at the point t12 when the laser pulse LP1 rises to form a spike, the light intensity continues for a period of approximately constant light intensity, and then the light intensity gradually decreases. In addition, there are laser oscillators that have the following characteristics. That is, from the rising time point t12 of the laser pulse LP1, the light intensity rises slowly, and then, the laser pulse whose light intensity continues to be substantially constant is output.

The control device 40 obtains the detection result of the light intensity of the laser pulse LP1 from the sensor 20 to detect the rise of the laser pulse LP1. For example, the time point when the light intensity of the laser pulse LP1 reaches a predetermined critical value is determined as the rising time point t12 of the laser pulse LP1. This critical value can be set based on, for example, the maximum value of the peak that appears immediately after the laser pulse rises, the average value of the light intensity during the period when the light intensity becomes substantially constant, and the like. As an example, the critical value may be set to 10% of the maximum value of the peak value. The control device 40, at a time point t13 when the constant standby time tw11 has elapsed from the rising time point t12 of the laser pulse LP1, raises the cut-out signal chp of the cut-out optical system 14 (FIG. 1) to order the start of the cutout. Shoot pulse LP2. The value of the constant standby time tw11 is previously input from the input device 41 (FIG. 1) and stored in the control device 40.

The control device 40 reduces the cut-out signal chp at the time point t14 when the time corresponding to the predetermined pulse width has elapsed from the time point t13 when the cut-out optical system 14 has instructed to start cutting out the laser pulse LP2. The optical system 14 orders the end of cutting out the laser pulse LP2. During the period from the rising time point t13 of the cut-out signal chp to the falling time point t14, the laser pulse LP2 is cut out from the laser pulse LP1.

The period from the time point t13 when the order is started to cut out to the time point t14 when the order is to end the cut out is set, for example, within a period in which the light intensity of the laser pulse LP1 changes substantially constantly.

The delay time td21 from the rising time t21 of the trigger signal trg of the second laser pulse LP1 to the rising time t22 of the laser pulse LP1 is not limited to the delay from the first laser pulse LP1 The time td11 is equal. The control device 40, at a time point t23 when the constant standby time tw21 has elapsed from the time point t22 when the second laser pulse LP1 is detected to start outputting, raises the cut-out signal chp to order the cut-out optical system 14 to start cutting. The laser pulse LP2 is emitted. The standby time tw21 of the second shot is equal to the standby time tw11 of the first shot.

The elapsed time from the time point t23 when the order has been ordered to the time point t24 when the order is finished is equal to the elapsed time from the time point t13 when the order is started to be cut out in the first round to the time point t14 when the order is finished. . The elapsed time from the rising time point t21 of the trigger signal trg to the falling time point t25 of the trigger signal trg is equal to the elapsed time from the rising time point t11 of the trigger signal trg in the first transmission to the falling time point t15.

Next, while comparing with the comparative example shown in FIG. 3, the excellent effect of the said Example is demonstrated. FIG. 3 is a graph showing the waveforms of the trigger signal trg, the laser pulse LP1, the cut-out signal chp, and the laser pulse LP2 in the pulse laser output device based on the comparative example. The timing and waveform of the trigger signal trg and the laser pulse LP1 are the same as those in the embodiment shown in FIG. 2.

In the comparative example, at the time point t13 when the constant standby time tw31 has elapsed from the rising time point t11 of the trigger signal trg, the cut-out signal chp is raised to order the start of the cut-out. The same is true in the second shot. At the time point t23 after the constant standby time tw41 has elapsed from the rising time point t21 of the trigger signal trg of the laser pulse LP1 that was ordered to start outputting, the cut-out signal chp is raised and the cut-out is ordered . The standby time tw41 in the second shot is equal to the standby time tw31 in the first shot.

In the first shot, the period from the time point t13 when the cutting-out order has been ordered to the time point t14 when the cutting-out end has been ordered falls within the period during which the light intensity of the laser pulse LP1 changes substantially constantly. However, in the second shot, the delay time td21 is longer than the delay time td11 of the first shot, so that the time point t23 when ordering to start cutting is within the peak value just after the laser pulse LP1 rises. Therefore, the waveform of the second laser pulse LP2 is significantly different from the waveform of the first laser pulse LP2. As a result, the pulse energy (energy per pulse) of the second laser pulse LP2 is different from the pulse energy of the first laser pulse LP2. This is because although there are deviations in the delay times td11 and td21 from the rising time t11, t21 of the trigger signal trg of the laser pulse LP1 when the command is started to the actual rising time t12, t22 of the laser pulse LP1, it is still different from the trigger signal When trg rises, a command to start cutting is issued synchronously.

On the other hand, in the above-mentioned embodiment, in synchronization with the actual rising time points t12 and t22 of the laser pulse LP1, the control device 40 instructs the cutting-out optical system 14 to start cutting. Therefore, it is not affected by the deviation of the delay time td11, td21 from the rising time point t11, t21 of the trigger signal trg to the actual rising time point t12, t22 of the laser pulse LP1, and the waveform of the determined laser pulse LP1 The position of the laser pulse LP2 is cut out. This can suppress the deviation of the pulse energy of the laser pulse LP2.

Next, the preferable length of the standby time tw11, tw21 (FIG. 2) is demonstrated. If the standby times tw11 and tw21 are too short, the beginning of the laser pulse LP2 will cover a part of the peak just after the laser pulse LP1 rises. If the beginning of the laser pulse LP2 covers a part of the peak of the laser pulse LP1, the pulse energy of the laser pulse LP2 will vary greatly due to a small change in the waveform of the laser pulse LP1, for example, a small change in the peak width. In order to suppress the deviation of the pulse energy of the laser pulse LP2 caused by the change in the waveform of the laser pulse LP1, the standby times tw11 and tw21 are preferably set to be longer than the time width of the peak immediately after the laser pulse LP1 rises.

Even during the period in which the light intensity of the laser pulse LP1 changes substantially constantly, the light intensity gradually changes in accordance with the characteristics of the laser oscillator 10. It is preferable to set the standby time tw11 and tw21 in such a way that the laser pulse LP2 is cut out from the portion where the time change of the light intensity of the laser pulse LP1 is as small as possible. By setting the standby time tw11 and tw21 in this way, even if the waveform of the laser pulse LP1 slightly changes, it is difficult to produce a fluctuation in the pulse energy of the laser pulse LP2.

Therefore, regarding the standby time tw11 and tw21 (FIG. 2) of the pulse laser output device based on the above-mentioned embodiment, the waveform of the actual laser pulse LP1 can be observed, and the laser can be cut out from the period during which the light intensity remains approximately constant. It is better to set the pulse LP2. In the above-mentioned embodiment, when the laser pulse LP1 shows other waveforms, it can also be applied to a situation where the light intensity gradually increases from the point when the output starts, and then becomes substantially constant.

Next, a modification of the above-mentioned embodiment will be described. In the above embodiment, the pulse laser output device is used in the drilling process of the printed circuit board. In addition, the pulse laser output device based on the embodiment can be used for the following purposes, that is, the use of laser processing using a laser pulse obtained by cutting a part of the laser pulse output from the laser oscillator .

Next, referring to FIGS. 4 and 5, the pulse laser output device based on other embodiments will be described. Hereinafter, a description of the configuration common to the pulse laser output device shown in FIGS. 1 and 2 will be omitted.

Fig. 4 is a schematic diagram of a pulse laser output device based on this embodiment. In the embodiment shown in FIG. 1, a laser pulse LP2 is cut out from the laser pulse LP1 by the cut-out optical system 14 and propagated along a processing path. In contrast, in the pulse laser output device shown in FIG. 4, the cutting-out optical system 14 cuts out two laser pulses LP2 and LP3 from the laser pulse LP1, and propagates the laser along different processing paths. Pulse LP2, LP3.

In the processing path of the propagation of the laser pulses LP2 and LP3, respectively, similar to the processing path of the pulse laser output device shown in FIG. 1, a folding mirror 16, a scanning optical system 17, a lens 19, a stage 30 and a moving Agency 31. With the laser pulses LP2 and LP3, two workpieces 50 can be processed simultaneously.

Fig. 5 is a chart showing the waveforms of the trigger signal trg, the laser pulse LP1, the cut-out signal chp, and the laser pulses LP2 and LP3. Figure 5 shows the output period of a laser pulse LP1.

The waveforms 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. 2. When the control device 40 detects the rise of the laser pulse LP1, at the time t13 when the constant standby time tw11 has elapsed from the rise time t12 of the laser pulse LP1, the optical system 14 (FIG. 4) The cutting out signal chp rises and the laser pulse LP2 is ordered to start cutting out. At the time point t14 when the time corresponding to the predetermined pulse width has elapsed from the time point t13 when the cut-out optical system 14 has ordered to start cutting out the laser pulse LP2, the cut-out signal chp is lowered to cut out the optical system 14 Order to end the laser pulse LP2.

In addition, the control device 40, at a time point t16 when the constant standby time tw12 has elapsed from the rising time point t12 of the laser pulse LP1, raises the cut-out signal chp of the cut-out optical system 14 (FIG. 4) to order the start of cutting. The laser pulse LP3 is emitted. The standby time tw12 is longer than the sum of the standby time tw11 and the pulse width (t14-t13). Regarding the instruction to start cutting out of the laser pulse LP2 and the instruction to start cutting out of the laser pulse LP3, it can be distinguished by the magnitude of the cutting out signal chp, such as a voltage value. At the time t17 when the time corresponding to the predetermined pulse width has elapsed from the time point t16 when the cut-out optical system 14 has instructed to start cutting out the laser pulse LP3, the cut-out signal chp is lowered to cut out the optical system 14 Order to end the laser pulse LP3.

The period from the time point t13 when the laser pulse LP2 has been ordered to cut out to the time point t17 when the laser pulse LP3 has been ordered to cut out is set within a period in which the light intensity of the laser pulse LP1 changes substantially constantly.

Next, the excellent effects of the embodiment shown in FIGS. 4 and 5 will be described. In this embodiment, since the laser pulses LP2 and LP3 are also commanded to start cutting out in synchronization with the rising time t12 of the laser pulse LP1, even from the rising time t11 of the trigger signal trg to the rising time t12 of the laser pulse LP1 There is a deviation in the delay time td11 up to the time t12, and the laser pulses LP2 and LP3 can also be cut out from the period in which the light intensity of the laser pulse LP1 remains substantially constant.

In addition, in this embodiment, two processing objects 50 can be processed simultaneously in two processing paths. As a result, the processing capacity of laser processing is improved.

Next, a modification example of this embodiment will be described. In this embodiment, the standby time tw12 until the command to start cutting out the laser pulse LP3 is issued is specified by the time elapsed from the rising time point t12 of the laser pulse LP1. The elapsed time from the falling time t14 of the cut-out signal chp corresponding to the shot pulse LP2 is specified. In this case, since the standby time tw11 and the pulse width value of the laser pulse LP2 are preset, it can be said that the time at which the instruction to start cutting out the laser pulse LP3 is issued is synchronized with the rising time of the laser pulse LP1.

The foregoing embodiments are examples. Of course, the configurations shown in the different embodiments can be partially replaced or combined. Regarding the same action and effect based on the same configuration of the plural embodiments, it is not mentioned one by one in each embodiment. In addition, the present invention is not limited to the above-mentioned embodiment. For example, it is obvious to those skilled in the art that various changes, improvements and combinations can be made.

10: Laser oscillator 11: Beam splitter 12: Illumination optical system 13: Aperture 14: Cut out the optical system 15: beam damper 16: reentrant mirror 17: Scanning optical system 18X, 18Y: movable mirror 19: lens 20: Sensor 30: Stage 31: mobile agency 40: control device 41: Input device 50: Object to be processed

[Fig. 1] A schematic diagram of a pulse laser output device based on the embodiment. [FIG. 2] A graph showing the waveforms of the trigger signal trg, the laser pulse LP1, the cut-out signal chp, and the laser pulse LP2 of the pulse laser output device based on the embodiment. [Fig. 3] A graph showing the waveforms of the trigger signal trg, the laser pulse LP1, the cut-out signal chp, and the laser pulse LP2 of the pulse laser output device based on the comparative example. [Fig. 4] A schematic diagram of a pulse laser output device based on another embodiment. [FIG. 5] A graph showing the waveforms of the trigger signal trg, the laser pulse LP1, the cut-out signal chp, and the laser pulse LP2 of the pulse laser output device based on another embodiment.

t11~t15: time point

t21~t25: time point

td11: delay time

td21: delay time

tw11: standby time

tw21: standby time

trg: trigger signal

LP1: Laser pulse

chp: cut out signal

LP2: Laser pulse

Claims (6)

A laser control device which, in synchronization with the rising time of the laser pulse output from the laser oscillator, orders a cutting optical system that cuts a part of the laser pulse output from the laser oscillator to start cutting. The laser control device according to claim 1, wherein the cut-out optical system is also ordered to end the cut-out. The laser control device according to claim 1 or 2, wherein the value of the standby time from the point when the laser pulse rises to the point when the laser pulse is ordered to be cut out is also acquired, and after the rise of the laser pulse is detected At the time point when the time equivalent to the obtained standby time value has passed, the cutting-out optical system is ordered to start cutting out the laser pulse. A pulse laser output device, which has: Laser oscillator, output pulse laser beam; The sensor detects the light intensity of the pulsed laser beam output from the aforementioned laser oscillator; Cut out the optical system, cut out a part of the laser pulse of the pulsed laser beam output from the aforementioned laser oscillator; and The control device obtains the detection result from the sensor to detect the rising time of the laser pulse, and in synchronization with the rising time of the laser pulse, orders the cutting-out optical system to start cutting out the laser pulse. The pulse laser output device according to claim 4, wherein: The aforementioned control device stores the pulse width value of the laser pulse that should be cut out. After the cut-out optical system is instructed to start cutting out the laser pulse, a time period equivalent to the pulse width of the laser pulse that should be cut out has elapsed At this point, the cut-out optical system is ordered to end the cut-out. The pulse laser output device according to claim 4 or 5, wherein: It also has an input device that receives the value of the standby time from the rising time of the laser pulse to the time when the laser pulse is ordered to be cut out, The aforementioned control device orders the aforementioned cut-out optical system to start cutting out the laser pulse at the time point when the time equivalent to the obtained standby time value has elapsed from the point of detecting the rise of the laser pulse.

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