JP2003347636A - Q-switched laser apparatus and method for controlling q-switching - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a Q-switched laser apparatus capable of obtaining stable processing quality while suppressing an output of a first pulse having a high peak value. <P>SOLUTION: In a controlling data select circuit 23, once a laser output start signal is inputted from the outside, optimum Q-switching controlling data is derived from a controlling data memory section 21 and is sent to a control signal output circuit 24, the Q-switching controlling data is converted to voltage (an initial output adjusting signal adjusted in an amplitude level) and is sent to a Q-switching device drive circuit 25. In the Q-switching device drive circuit 25, a high frequency output is generated on the basis of the inputted initial output adjusting signal to control the operation of a Q-switching device 16. <P>COPYRIGHT: (C)2004,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a Q-switch laser device for controlling a Q-switch element to oscillate and output laser light, and a Q-switch control method.

[0002]

2. Description of the Related Art A Q switch laser device used as a laser trimming device, a laser marking device, or the like is a Q switch laser device.
It comprises a switch laser oscillator and a Q switch controller. When the laser oscillation stops due to the suppression of the Q switch element, the light energy (excitation energy) obtained by the excitation of the excitation light source is stored in the laser medium, and the suppression by the Q switch element is released. The laser pulse is emitted at the moment when it is set.

The peak value of the laser pulse increases as the laser stop time due to suppression of the Q switch element increases, and becomes maximum when the stop time exceeds the upper level life of the laser medium. In particular, at the start of laser pulse oscillation, a laser pulse having a high peak value called a first pulse is output because a laser pulse is generated in a state where the excitation energy in the laser medium is sufficiently high.

Further, for example, when laser processing is performed by outputting laser pulses at a high repetition, that is, when the excitation energy in the laser medium is not sufficiently accumulated, a laser pulse having a lower peak value than the first pulse is generated. When processing is performed by outputting, a difference between the peak value and the first pulse appears as a processing difference, which causes a problem in processing quality. Therefore, a technique for suppressing the first pulse is required.

[0005] An example of the prior art capable of suppressing the first pulse is disclosed in Japanese Patent Application Laid-Open No. 2-290090.
It is disclosed as a Q-switched laser device. An example of a conventional technique capable of suppressing a first pulse is disclosed in
001-313434 discloses a Q-switched laser device.

The Q-switch laser devices described in these publications gradually reduce high-frequency power applied to the Q-switch element with a predetermined time constant, gradually discharge pump energy stored in the laser medium, and attenuate the first pulse. By doing so, the first pulse is suppressed.

[0007]

However, in the conventional Q-switched laser device, it is necessary to discharge extra energy accumulated in the laser medium at a stage before generating a desired laser pulse. There has been a problem that it takes a considerable time to obtain a pulse. Furthermore, when discharging extra energy stored in the laser medium, it is necessary to perform extraneous laser oscillation, which has been a factor of deteriorating the processing quality.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and can suppress the first pulse without requiring a considerable time and without performing an extraordinary laser oscillation, and can achieve a stable processing quality. It is an object of the present invention to provide a Q-switch laser device and a Q-switch control method capable of obtaining the following.

Another conventional example capable of generating a laser pulse having a substantially constant peak value is disclosed in JP-A-60-0959.
No. 88 discloses a driving method for a Q-switch laser device. The driving method of the Q-switch laser device disclosed in this publication does not disclose any technique for controlling the amplitude level of the modulation signal, any data used for controlling the modulation signal, and any technique for selecting this data. Therefore, the above-mentioned object could not be achieved even in the conventional example.

A conventional example in which optimal Q-switching modulation control is performed in accordance with the amount of pumping energy stored in a laser oscillator is disclosed in Japanese Patent Laid-Open No. 2000-101176 as a Q-switch type laser device. The Q-switch type laser device disclosed in this publication adjusts the high-frequency level when the laser is turned off, leaks the laser, and controls the laser so that the accumulated amount of the laser becomes uniform. The subsequent laser pulse power is made uniform.

For this reason, the prior art Q-switch type laser device does not disclose any technique for suppressing the first pulse. For this reason, the Q
Since the switching type laser device cannot maintain the processing quality that cannot be used for suppressing the first pulse, the above-mentioned object cannot be achieved even in the conventional example.

[0012]

In order to achieve the above object, a Q-switch laser device according to claim 1 of the present invention comprises:
A laser having a laser oscillator including a Q-switch element for controlling the oscillation output of laser light, and a Q-switch controller for controlling the operation of the Q-switch element based on a high-frequency output
A switch laser device, wherein a Q switch controller includes a control signal output circuit that adjusts an amplitude level of an initial output adjustment signal at a plurality of timings at which a laser oscillator oscillates laser light, and a first stage in which laser light is oscillated. Receiving an initial output adjustment signal from the control signal output circuit, forming a high-frequency output waveform based on the input initial output adjustment signal, and forming a Q-switch element based on the high-frequency output formed with the waveform. Q to control the operation of
And a switch element driving circuit.

When the Q-switch laser device is configured as described above, the control signal output circuit outputs an initial output adjustment signal whose amplitude level has been adjusted before outputting an ON / OFF signal for oscillating ordinary laser light. can do. Then, based on the initial output adjustment signal, the Q-switch element driving circuit, at the start of laser oscillation (the first stage in which laser light is oscillated), based on the high-frequency output whose amplitude level has been adjusted a plurality, Can be controlled.

Thus, the laser oscillator operates as a laser OF.
The excitation energy stored in the laser medium at the time of F (time when the laser light is not oscillated) is dispersed into a plurality of laser lights having a suppressed peak value by the output control of the Q switch element based on the high frequency output. Can be released. Therefore, the output of the first pulse having a high peak value can be suppressed, and a laser pulse having a uniform peak value can be obtained.

Further, the operation performed by the conventional Q-switched laser device, for example, the operation of discharging all or a part of the excess energy stored in the laser medium before oscillating the normal laser light, Since it is not necessary to accompany the operation of oscillating a different kind of laser beam when the extra energy is discharged, stable processing quality can be obtained. In addition, since an extra unit such as an external switch for deleting the first pulse is not required, a device for deleting the first pulse can be manufactured at low cost.

According to a second aspect of the present invention, in the Q switch laser device, the Q switch controller includes a control data storage unit for storing a plurality of Q switch control data, and one or more of the plurality of Q switch control data. A control data selection circuit for selecting the Q switch control data and extracting the data from the control data storage unit, wherein the control signal output circuit is configured to perform an initial operation based on one or more Q switch control data from the control data selection circuit. The configuration is such that the amplitude level of the output adjustment signal is adjusted.

With such a configuration of the Q-switched laser device, the amplitude level of the initial output adjustment signal can be adjusted based on the Q-switch control data. Then, as the Q switch control data used for adjusting the amplitude level, an appropriate one is selected in the control data selection circuit according to the state of the excitation energy (energy stored in the laser medium). Further, the Q-switch element driving circuit can form a high-frequency output waveform based on the initial output adjustment signal output based on the appropriate Q-switch control data.

Therefore, the laser oscillator can control the first pulse by controlling the operation of the Q switch based on the high frequency output, and can oscillate the laser at a constant peak value. Then, by using this constant level of laser light, stable processing quality can be obtained.

Further, in the Q-switch laser device according to the third aspect, a plurality of Q-switch control data are created based on excitation conditions such as an excitation state of a laser medium, a laser stop time and / or a laser oscillation frequency. The control data selection circuit converts the Q-switch control data corresponding to the excitation condition at the first stage at which the oscillation of the laser light is started into a plurality of Q-switch control data.
The switch control data is selected and taken out from the control data storage unit.

When the Q-switched laser device is configured as described above, the combination of each condition value of excitation conditions (excitation state of laser medium, laser stop time, laser oscillation frequency, etc.) is patterned, and the Q value corresponding to each pattern is obtained. The switch control data can be stored in the control data storage unit. Then, the control data selection circuit selects Q switch control data corresponding to the excitation state of the laser oscillator at the start of laser light oscillation from the plurality of Q switch control data stored in the control data storage unit. can do.

That is, the selected Q-switch control data is the Q-switch control data capable of suppressing the output of the first pulse most effectively based on the current excitation state of the laser oscillator. Therefore, even when the laser oscillator is in an excited state in which the output of the first pulse is oscillated, the output of the first pulse can be surely suppressed.

According to a fourth aspect of the present invention, the Q-switch control data includes a plurality of timing and / or initial output adjustment signals such that the excitation energy stored in the laser medium is dispersed and emitted. It is configured to set the amplitude level. With such a configuration of the Q-switch laser device, it is possible to suppress the output of the first pulse having a high peak value.

In the Q-switch laser device according to the fifth aspect, the control signal output circuit adjusts each amplitude level of the initial output adjustment signal so as to change stepwise. If the Q switch laser device has such a configuration,
Since the amplitude level of the high frequency output for controlling the Q switch element is controlled stepwise, the excitation energy stored in the laser medium can be divided and emitted as several laser pulses.

Thus, it is possible to suppress the output of a laser pulse having a high peak value called a first pulse generated at the start of laser pulse oscillation, and to obtain a laser pulse having a uniform peak value from the start of the laser oscillation. it can. Therefore, in laser processing using a laser pulse having a uniform peak value, stable processing quality can be obtained.

According to a sixth aspect of the present invention, the control signal output circuit adjusts the amplitude level and / or the switching width of the initial output adjustment signal based on the Q switch control data, and drives the Q switch element. The circuit is configured to form a high-frequency output waveform based on a Q-switch control signal from a control signal output circuit.

When the Q-switch laser device has such a configuration, the control signal output circuit or the Q-switch element driving circuit can adjust the initial output adjustment signal or the high-frequency output not only for the amplitude level but also for the switching width. it can. Therefore, for example, even when the excitation energy stored in the laser medium cannot be divided into uniform laser pulses, a high-frequency output can be adjusted by the switching width to obtain a uniform laser beam.

According to a seventh aspect of the present invention, in the Q switch control method, the Q switch controller controls the operation using the high frequency output for the Q switch element for controlling the output of the laser light oscillated from the laser oscillator. In a switch control method, a Q-switch controller adjusts an amplitude level of an initial output adjustment signal at a plurality of timings at which a laser oscillator oscillates a laser beam. In this method, a waveform of a high-frequency output is formed based on the high-frequency output, and the operation of the Q-switch element is controlled based on the high-frequency output formed with the waveform.

If the Q-switch control method is such a method, the operation of the Q-switch element is controlled based on a plurality of high-frequency outputs whose amplitude levels are adjusted when the oscillation of the laser beam is started. Excitation energy of the laser medium accumulated when the laser is turned off can be dispersed and emitted.

For this reason, it is possible to suppress the output of the first pulse having a high peak value and quickly obtain a laser pulse having a desired peak value. Further, it is not necessary to discharge all or a part of the excess energy accumulated in the laser medium at a stage before generating a desired laser pulse as in a conventional Q-switched laser device. Obtainable.

[0030]

Embodiments of the present invention will be described below with reference to the drawings. First, an embodiment of a Q-switch laser device and a Q-switch control method of the present invention will be described with reference to FIG. FIG.
FIG. 3 is a block diagram illustrating a configuration of a switch laser device.

As shown in FIG. 1, a Q-switch laser device 1 comprises a laser oscillator 10 and a Q-switch controller 2.
0. The laser oscillator (continuous oscillation laser device) 10 includes an excitation light source 11, an excitation light power supply 12, a laser medium 13, a reflection mirror 14, an emission mirror 15,
And a Q switch element 16.

The excitation light source 11 receives power supply from an excitation light power source 12 to irradiate the laser medium 13 with excitation light to stimulate stimulated emission of light. The laser medium 13 is
It is excited by substantially constant light emitted from the excitation light source 11, and emits substantially constant light in the axial direction from both end surfaces thereof. The reflection mirror 14 and the emission mirror 15 are placed at positions facing each other, and repeatedly reflect stimulated emission light from the laser medium 13. Then, the emission mirror 15 emits the Q-switch pulse laser light in a direction opposite to the reflection direction.

Q switch element (acousto-optic Q switch) 1
6 diffracts the stimulated emission light from the laser medium 13 by the acousto-optic effect (reduces the Q value) while the high-frequency output is supplied from the Q switch element drive circuit 25 (described later), and reduces the inside of the resonator. , The excitation energy (inversion distribution) is increased.

When the high-frequency output is cut off, the Q-switching element 16 causes the stimulated emission light to go straight (returning the Q value), and oscillates at once with the stored excitation energy. It functions to generate light (laser light). The amount of laser light deflected by the Q switch element 16 is
Changes with the level of high-frequency power given to
The laser power output to the outside also changes.

The Q switch controller 20 has a control data storage unit 21, an oscillation timing generation circuit 22, a control data selection circuit 23, a control signal output circuit 24, and a Q switch element driving circuit 25. The control data storage unit 21 stores the Q switch control data.

The Q-switch control data is created corresponding to a plurality of patterns in which various condition values of excitation conditions (excitation state of laser medium, laser stop time, laser oscillation frequency, etc.) are combined. In practice, the Q-switch control data is
It is created based on the data on the excitation condition obtained by the oscillation test or the like.

The Q switch control data sets a plurality of timings, the amplitude level of the initial output adjustment signal, and the like so that the excitation energy accumulated in the laser medium is dispersed and emitted. Thus, the output of the first pulse having a high peak value can be suppressed. Oscillation timing generation circuit 2
2 outputs a synchronization signal. This synchronization signal is output in accordance with the laser pulse oscillation interval.

Upon receiving an external signal (laser output start signal) indicating the start of laser output, the control data selection circuit 23 immediately converts the optimum Q switch control data to
The data is selected and extracted from the plurality of Q-switch control data stored in the control data storage unit 21. The selection of the optimum Q-switch control data is performed based on the time elapsed since the last laser pulse oscillation and the excitation conditions such as the laser pulse oscillation frequency. As a result, the Q-switch control data that effectively suppresses the output of the first pulse having a high peak value is selected.

Then, the control data selection circuit 23 sends the extracted Q-switch control data to the control signal output circuit 24 in accordance with the synchronization signal from the oscillation timing generation circuit 22. Further, the control data selection circuit 23
When all the switch control data is sent to the control signal output circuit 24, thereafter, data that becomes an ON / OFF signal is repeatedly output until an external signal (laser oscillation stop signal) indicating stop of laser oscillation is input.

The control signal output circuit 24 has a function of converting the Q switch control data from the control data selection circuit 23 into a voltage (initial output adjustment signal) and sending it to the Q switch element driving circuit 25. / A circuit. The initial output adjustment signal is sent to the Q switch element drive circuit 25 as a Q switch control signal. That is, as shown in FIG. 2, the Q-switch control signal (a) disperses the ON / OFF signal (a1) for oscillating ordinary laser light and the excitation energy accumulated in the laser medium 13 before the start of laser oscillation. And an initial output adjustment signal (a2) for causing the emission.

The amplitude level (AL) of the initial output adjustment signal is adjusted at a plurality of timings at which the laser oscillator 10 oscillates laser light based on the Q switch control data, and is sent to the Q switch element drive circuit 25. . Then, the control signal output circuit 24 adjusts the plurality of amplitude levels (AL) adjusted at the oscillation timing of the laser light so as to change (for example, decrease) stepwise for each of the amplitude levels (AL). be able to.

By generating such an initial output adjustment signal as a Q switch control signal, the amplitude level of the high frequency output for controlling the Q switch element can be controlled in a stepwise manner. The laser pulses can be divided and emitted.

When a voltage (Q switch control signal) is input from the control signal output circuit 24, the Q switch element driving circuit 25 outputs high frequency power corresponding to this voltage level to the Q switch element 16 as a high frequency output. Since the Q-switch control signal ((a) in FIG. 2) includes the ON / OFF signal (a1) and the initial output adjustment signal (a2), the high-frequency output also has a waveform formed based on these signals. You.

Q switch element drive circuit 25 is ON / OF
The case where the F signal (a1) is input means that the laser oscillator 10
Is a case where a normal laser beam is oscillated. In this case, the Q-switch element driving circuit 25
When the laser light is output from 0, the output of the high-frequency power is stopped. On the other hand, when the output of the laser light is stopped, the output is performed so that the high-frequency power is maximized.

The case where the Q-switch element driving circuit 25 receives the initial output adjustment signal (a2) is when the laser beam starts to be oscillated (the first stage where the laser beam is oscillated) and has a peak value. This is a case where the output of a fast pulse having a high frequency can be oscillated. In this case, when laser light is output from the laser oscillator 10, the Q-switch element driving circuit 25 outputs high-frequency power having a low amplitude level (AL). On the other hand, when the output of the laser light is stopped, the output is performed so that the high-frequency power is maximized.

The initial output adjustment signal used for forming the high-frequency output waveform in the Q switch element driving circuit 25 is
In order to disperse and emit the excitation energy stored in the laser medium 13, the amplitude level (AL) is adjusted at a plurality of timings of the emission. The adjusted amplitude level (AL) is determined based on the Q switch control data.

Therefore, when the control data selection circuit 23 selects appropriate Q-switch control data, the laser oscillator 10 can emit a normal laser beam even at the start of laser oscillation, as shown in FIG. Output (c2) having the same peak value as the oscillation output (laser output) (c1) of
Can be oscillated. Therefore, even at the start of laser oscillation where a fast pulse has been generated conventionally,
The laser oscillator 10 can output a desired laser pulse while suppressing generation of a first pulse.

Next, the operation (Q-switch control method) of the Q-switch laser device of this embodiment will be described with reference to FIGS.
This will be described with reference to FIG. Q-switch control data that can obtain a constant pulse in accordance with the excitation conditions (excitation state of the laser medium, laser stop time, laser oscillation frequency, etc.) is obtained in advance by an oscillation test or the like. Control data storage unit 21 for each combination pattern of
To save.

When a laser output start signal is input from the outside to the control data selection circuit 23, the control data is immediately stored in the control data selection circuit 23 based on the condition such as the time elapsed since the last laser pulse oscillation and the laser pulse oscillation frequency. The optimum Q-switch control data is selected and extracted from the plurality of Q-switch control data stored in the unit 21. Then, the extracted Q-switch control data is sent to the control signal output circuit 24 in synchronization with the synchronization signal from the oscillation timing generation circuit 22.

In the control signal output circuit 24, the Q switch control data is converted into a voltage (initial output adjustment signal) and sent to the Q switch element drive circuit 25. In the Q-switch element driving circuit 25, a high-frequency output waveform is formed based on the input initial output adjustment signal, and is output to the Q-switch element 16.

Thereafter, when all the Q-switch control data is output from the control data selection circuit 23, data such that the Q-switch control signal becomes an ON / OFF signal until a laser oscillation stop signal is input from the outside is output. Output repeatedly. With such an operation, the Q-switch laser device can obtain a stable laser output as a result.

As another method of dividing the excitation energy accumulated in the laser medium 13 into several laser pulses and emitting the divided laser pulses, as shown in FIG. 3, an initial output adjustment signal of the Q switch control signal (a) is used. Regarding (a2), there is a method of changing not only the amplitude level (AL) but also the switching width (CW).

According to this method, it is possible to adjust the peak value of the laser beam which changes based on the excitation energy accumulated after the second pulse. Such a configuration can be used for adjusting laser light when the excitation energy stored in the laser medium cannot be divided into uniform laser pulses.

[0054]

As described above, according to the present invention, the amplitude level and the like of the high-frequency power output from the Q-switch element drive circuit are controlled stepwise according to the excitation energy stored in the laser medium. Therefore, it is possible to suppress the output of the first pulse having a high peak value and quickly obtain a laser pulse having a desired peak value.

Thus, it is not necessary to discharge all or a part of the excess energy stored in the laser medium before oscillating a desired laser pulse. Since stable laser oscillation is not performed, stable processing quality can be obtained. Further, since it is not necessary to install an extra unit such as an external switch to delete the first pulse, a device for deleting the first pulse can be manufactured at low cost.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a Q-switch laser device of the present invention.

FIG. 2 is a timing chart showing changes in a Q switch control signal, a high frequency output, and a laser output controlled by the Q switch laser device of the present invention.

FIG. 3 is a timing chart showing other changes in a Q-switch control signal, a high-frequency output, and a laser output controlled by the Q-switch laser device of the present invention.

[Explanation of symbols]

1 Q switch laser device 10 Laser oscillator 11 Excitation light source 12 Excitation light power supply 13 Laser medium 14 Reflection mirror 15 Exit mirror 16 Q switch element 20 Q switch controller 21 Control data storage unit 22 Oscillation timing generator 23 Control data selection circuit 24 Control signal output circuit 25 Q switch element drive circuit

Claims (7)

[Claims] 1. A Q-switch laser device comprising: a laser oscillator including a Q-switch element for controlling an oscillation output of a laser beam; and a Q-switch controller for controlling the operation of the Q-switch element based on a high-frequency output. A control signal output circuit that adjusts an amplitude level of an initial output adjustment signal at a plurality of timings at which the laser oscillator oscillates the laser light; and Receiving the initial output adjustment signal from the control signal output circuit, forming the high-frequency output waveform based on the input initial output adjustment signal, and forming the Q based on the high-frequency output having the waveform formed. A Q-switch laser device, comprising: a Q-switch element driving circuit for controlling operation of the switch element. . 2. A control data storage unit for storing a plurality of Q switch control data, wherein the Q switch controller selects one or two or more Q switch control data from the plurality of Q switch control data, A control data selection circuit to be taken out from the control data storage unit, wherein the control signal output circuit is configured to output the initial output adjustment signal based on the one or more Q switch control data from the control data selection circuit. 2. The Q-switched laser device according to claim 1, wherein the amplitude level is adjusted. 3. The control data selection circuit according to claim 1, wherein the control data selection circuit includes a plurality of the Q-switch control data based on excitation conditions such as an excitation state of a laser medium, a laser stop time, and / or a laser oscillation frequency. The Q-switch control data corresponding to the excitation condition at the first stage at which oscillation of the oscillation is started is selected from the plurality of Q-switch control data and taken out from the control data storage unit. 3. The Q-switch laser device according to 1 or 2. 4. The method according to claim 1, wherein the plurality of timings and / or the amplitude level of the initial output adjustment signal are set so that the Q-switch control data disperses and emits the excitation energy stored in the laser medium. The Q-switched laser device according to claim 1, 2, or 3, wherein 5. The Q switch according to claim 1, wherein said control signal output circuit adjusts each of said amplitude levels of said initial output adjustment signal so as to change stepwise. Laser device. 6. The control signal output circuit adjusts the amplitude level and / or switching width of the initial output adjustment signal based on the Q switch control data, and the Q switch element driving circuit controls the control signal. 6. The high-frequency output waveform is formed based on the Q-switch control signal from an output circuit.
The Q-switch laser device according to any one of the above. 7. A Q-switch control method in which a Q-switch controller controls an operation using a high-frequency output for a Q-switch element that controls the output of a laser beam oscillated from a laser oscillator. Adjusting the amplitude level of the initial output adjustment signal at a plurality of timings at which the laser oscillator oscillates the laser light, at the first stage in which the laser light is oscillated, based on the initial output adjustment signal, A Q-switch control method, comprising: forming an output waveform; and controlling the operation of the Q-switch element based on a high-frequency output having the waveform formed.