JP2022013192A - Pulse laser device and control method for pulse laser device - Google Patents

Abstract

To suppress a change in a waveform of pulse laser light before and after amplification in an optical amplifier.SOLUTION: A pulse laser device comprises: a light source which outputs pulse laser light which is pulse-modulated by a laser light source drive signal; a laser light source drive section which outputs the laser light source drive signal; an electro-optical modulator drive section which outputs a modulator drive signal; an electro-optical modulator for outputting pulse laser light for which the pulse laser light outputted by the light source is further pulse-modulated by the modulator drive signal; and a control section which controls the laser light source drive section and the electro-optical modulator drive section in such a manner that the electro-optical modulator is turned on while at least the light source is turned in for the pulse modulation to the light source and the pulse modulation to the electro-optical modulator. The electro-optical modulator drive section shapes a waveform of the modulator drive signal into a waveform of a pulse width corresponding to a time width for turning on the electro-optical modulator in a predetermined shape, and the time width is variable.SELECTED DRAWING: Figure 1

Description

The present invention relates to a pulse laser device and a control method for the pulse laser device.

Patent Document 1 discloses a so-called MOPA (Master Oscillator Power Amplifier) type pulse laser device that amplifies pulse laser light as seed light with an optical amplifier such as an optical fiber amplifier and outputs high-intensity pulse laser light. Has been done. In the MOPA type pulse laser device, a part of the pulse laser light is cut out as a rectangular wave by an intensity modulation type electro-optic modulator (EOM) according to the application and material of laser processing, and the seed light is used. The pulse width can be changed to optimize machining.

International Publication No. 2018/105733

The pulsed laser light of the square wave cut out by the electro-optical modulator is amplified by an optical amplifier such as an optical fiber amplifier. In an optical amplifier with a population inversion, when pulsed laser light is input, the electrons in the upper level decrease from the time when the pulsed laser light is input, so the intensity of the light output from the optical amplifier is pulsed. The rise of the laser beam peaks and becomes smaller. Therefore, the waveform of the input pulse laser light is a square wave, but the waveform of the intensity of the pulse laser light output from the optical amplifier is not a square wave but a waveform whose intensity continues to decrease until the fall, and is input. The waveform to be output and the waveform to be output do not correspond to each other. In addition, in machining with pulsed laser light, if the waveform becomes a waveform in which the intensity peaks at the rising edge and decreases to the falling edge, when the laser beam with an intensity equal to or higher than a certain threshold contributes to the machining, the total energy of the pulsed laser beam is used for machining. The energy that contributes becomes smaller.

The present invention has been made in view of the above, and an object of the present invention is to provide a technique capable of suppressing a change in the waveform of a pulsed laser beam before and after amplification by an optical amplifier.

In order to solve the above-mentioned problems and achieve the object, the pulse laser apparatus according to one aspect of the present invention comprises a laser light source, an electro-optical modulator, and a laser light source drive signal for driving the laser light source by pulse modulation. An output laser light source drive unit, an electro-optical modulator drive unit that outputs a modulator drive signal that drives the electro-optical modulator by pulse modulation, the laser light source drive unit, and the electro-optical modulator drive unit. The laser light source includes a control unit for controlling, the laser light source outputs a pulse laser light pulse-modulated by the laser light source drive signal, and the electro-optical modulator uses the pulse laser light output by the laser light source to modulate the pulse laser light. Further pulse-modulated pulse laser light is output by the device drive signal, and the control unit performs pulse modulation for the laser light source and pulse modulation for the electro-optical modulator at least while the laser light source is on. The laser light source drive unit and the electro-optical modulator drive unit are controlled so that the electro-optical modulator is turned on, and the electro-optical modulator drive unit shapes the waveform of the modulator drive signal into a predetermined shape. It is characterized in that the pulse width is shaped into a pulse width waveform according to the time width in which the electro-optical modulator is turned on, and the time width is variable.

In the pulse laser device according to one aspect of the present invention, the control unit outputs a pulse signal of a rectangular wave in which the electro-optical modulator is turned on, and the electro-optical modulator drive unit outputs a waveform of the pulse signal. A waveform shaping unit that shapes the pulse width according to the time width during which the electro-optical modulator is turned on in the predetermined shape, and a signal shaped by the waveform shaping unit is amplified and output as the modulator drive signal. It is characterized by including an amplification unit.

The pulsed laser apparatus according to one aspect of the present invention is characterized in that the waveform shaping unit is a band variable filter.

In the pulse laser apparatus according to one aspect of the present invention, the waveform shaping unit has a pulse width corresponding to the time width in which the electro-optical modulator is turned on, and the waveform of the pulse signal is larger than the pulse signal. It is characterized by shaping into a waveform with a long rise time and fall time.

The pulsed laser apparatus according to one aspect of the present invention is characterized in that the waveform has a Gaussian shape.

The pulse laser apparatus according to one aspect of the present invention is characterized in that the pulse width of the pulse laser light further pulse-modulated by the electro-optical modulator is 1 ns or less.

The pulsed laser apparatus according to one aspect of the present invention is further provided with an optical amplifier that amplifies the pulsed laser beam further pulse-modulated by the electro-optical modulator.

The control method of the pulse laser apparatus according to one aspect of the present invention includes a laser light source and an electro-optical modulator, the laser light source outputs pulse-modulated pulse laser light, and the electro-optical modulator A method for controlling a pulse laser device that outputs a pulsed laser beam obtained by further pulse-modulated a pulsed laser beam output by the laser source, wherein pulse modulation for the laser light source and pulse modulation for the electro-optical modulator are used. At least while the laser light source is on, the electro-optical modulator is turned on, and the waveform of the signal that turns the electro-optical modulator on is set to the electro-optical modulator in the on state in a predetermined shape. It is characterized in that it is shaped into a waveform having a pulse width corresponding to the time width to be applied, and the time width is variable.

According to the present invention, there is an effect that the change in the waveform of the pulsed laser beam can be suppressed before and after the amplification by the optical amplifier.

FIG. 1 is a block diagram of a pulse laser device according to an embodiment. FIG. 2 is a diagram showing an example of a time chart of a signal and an optical output in a pulse laser device. FIG. 3 is a diagram showing an example of a waveform of a shaping signal. FIG. 4 is a block diagram of the pulse laser device according to the modified example. FIG. 5 is a diagram showing an example of a time chart of a signal and an optical output in the pulse laser apparatus according to the modified example. FIG. 6 is a diagram showing an example of a waveform of a shaping signal. FIG. 7 is a diagram showing an example of a time chart of a signal and an optical output in a modified example.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. The present invention is not limited to the embodiments and modifications described below. Further, in the description of the drawings, the same or corresponding elements are appropriately designated by the same reference numerals.

[Embodiment]
FIG. 1 is a block diagram of a pulse laser device 100 according to an embodiment of the present invention. The pulse laser device 100 includes a seed light source unit 10, a drive unit 20, a control unit 30, a waveform shaping unit 90, a preamplifier 40, a booster amplifier 50, and an output unit 60. The seed light source unit 10 is connected to the preamplifier 40 by a single mode optical fiber. Further, the preamplifier 40 is connected to the booster amplifier 50 by a single mode optical fiber.

The seed light source unit 10 outputs the laser beam L1, which is a pulsed laser beam, as the seed light. The preamplifier 40 is an optical amplifier such as an optical fiber amplifier, and receives the laser beam L1. The preamplifier 40 amplifies the received laser light L1 and outputs it as the laser light L2 to the booster amplifier 50. The booster amplifier 50 is an optical amplifier such as an optical fiber amplifier which usually has a higher output than the preamplifier 40, and receives the laser beam L2. The booster amplifier 50 amplifies the received laser light L2 and outputs it as the laser light L3 to the output unit 60. The optical fiber amplifier is, for example, a rare earth-added optical fiber amplifier. Rare earths are erbium and ytterbium. The output unit 60 is composed of a known laser head, receives the laser light L3 from the booster amplifier 50 via the optical fiber, and outputs the received laser light L3 to the outside as the laser light L4. The laser beam L4 is used for a desired application (laser processing, etc.).

The seed light source unit 10 includes a semiconductor laser diode (LD: Laser Diode) 11 which is a laser light source, and an electro-optical modulator (EOM) 12. The LD 11 is a DFB (Distributed Feedback) laser element that outputs a single wavelength laser beam L01 included in, for example, a 1.55 μm wavelength band. The EOM 12 receives the laser light L01 output from the LD 11 and intensity-modulates the laser light L01 by the electro-optic effect and outputs the laser light L1. The seed light source unit 10 is driven by the drive unit 20.

The drive unit 20 includes an LD drive unit 21 which is a laser light source drive unit and an EOM drive unit 22. These drive units can be configured by using a known LD drive circuit or the like.

The control unit 30 is composed of a digital circuit including a CPU (Central Processing Unit) or an FPGA (Field Programmable Gate Array) for performing control processing of each drive unit included in the drive unit 20. The control unit 30 outputs the band control signal S16 for controlling the waveform shaping unit 90 to the waveform shaping unit 90. Further, the control unit 30 outputs the LD drive pulse signal S11 to the LD drive unit 21 and outputs the EOM drive pulse signal S12 to the waveform shaping unit 90. The LD drive pulse signal S11 and the EOM drive pulse signal S12 are pulse signals that are turned on in a predetermined repetition period and time width (pulse width), respectively, and turned off in other periods.

The LD drive unit 21 outputs the LD drive signal S21, which is a signal corresponding to the LD drive pulse signal S11, to the LD 11 and drives the LD 11 by pulse modulation. As a result, the laser beam L01 becomes a pulse-modulated pulsed laser beam.

The waveform shaping unit 90 is, for example, a band variable filter, which is a low-pass filter capable of changing the cutoff frequency according to external control. The waveform shaping unit 90 changes the pass band according to the band control signal S16. The EOM drive pulse signal S12 is waveform-shaped when passing through the waveform shaping unit 90, and is output as a shaping signal S15 which is a signal corresponding to the EOM drive pulse signal S12. The EOM drive unit 22 and the waveform shaping unit 90 function as an electro-optical modulator drive unit that drives the EOM 12.

The EOM drive unit 22 is, for example, an RF (Radio Frequency) amplifier, outputs an EOM drive signal S22 which is a signal corresponding to the shaping signal S15 to the EOM 12, and drives the EOM 12 by pulse modulation. The EOM drive unit 22 is an example of an amplification unit. As a result, the laser beam L01 becomes the laser beam L1, which is pulsed laser beam further pulse-modulated.

FIG. 2 is a diagram showing an example of a time chart of various signals and optical outputs in the pulse laser apparatus 100. In FIG. 2, the laser beam L01 and the laser beam L1 show intensity waveforms. The LD drive pulse signal S11 output by the control unit 30 to the LD drive unit 21 is a pulse signal that is turned on with a constant pulse width centered on time t1 and t2 in the time range shown in the figure and is turned off in other periods. be. The repetition period of the LD drive pulse signal S11 output from the control unit 30 to the LD drive unit 21 is T1, and the repetition frequency is constant at f1 = 1 / T1. The LD drive signal S21 output from the LD drive unit 21 in response to the LD drive pulse signal S11 is a signal synchronized with the LD drive pulse signal S11. As a result, the laser light L01 (LD light output) output from the LD 11 also becomes a pulse laser light composed of an optical pulse train synchronized with the LD drive pulse signal S11 and the LD drive signal S21.

The EOM drive pulse signal S12 output by the control unit 30 to the waveform shaping unit 90 is a pulse signal that is turned on with a pulse width w1 according to the application and material of laser processing and is turned off during other periods, and is repeated. The period is T1. The pulse width w1 of the EOM drive pulse signal S12 is, for example, in the range of 100 ps to 1 ns.

The control unit 30 controls the pass band of the waveform shaping unit 90 with the band control signal S16. For example, the control unit 30 controls the pass band with the band control signal S16 to a frequency band equal to or less than the inverse of the pulse width w1 of the EOM drive pulse signal S12, and when the pulse width w1 is 100 ps, the pass band of the waveform shaping unit 90 is set. Set to 10 GHz or less. Further, for example, when the pulse width w1 of the EOM drive pulse signal S12 is 500 ps, the control unit 30 sets the pass band of the waveform shaping unit 90 to 2 GHz or less, and when the pulse width w1 is 1 ns, the passage of the waveform shaping unit 90. Set the band to 1 GHz or less.

(A) to (c) of FIG. 3 show an example of the waveform of the shaping signal S15 which is a signal passing through the waveform shaping unit 90, and (d) to (f) of FIG. 3 show the EOM drive pulse signal S12. An example of the waveform is shown. The rise time and fall time of the EOM drive pulse signal S12 are set to 100 ps. FIG. 3D shows the waveform of the EOM drive pulse signal S12 when the pulse width w1 is 100 ps, and FIG. 3A shows the waveform shaping when the pulse width w1 of the EOM drive pulse signal S12 is 100 ps. This is the waveform of the shaping signal S15 when the pass band of the unit 90 is set to 10 GHz or less. In this case, since the pass band of the waveform shaping unit 90 is equal to the inverse of the rise time and fall time of the EOM drive pulse signal S12 (10 GHz), the waveform of the shape shaping signal S15 is substantially different from the waveform of the EOM drive pulse signal S12. However, the rising time and falling time of the shaping signal S15 are 100 ps, and the pulse width (half width) of the shaping signal S15 is 100 ps.

FIG. 3 (e) shows the waveform of the EOM drive pulse signal S12 when the pulse width w1 is 500 ps, and FIG. 3 (b) shows the waveform shaping when the pulse width w1 of the EOM drive pulse signal S12 is 500 ps. This is the waveform of the shaping signal S15 when the pass band of the unit 90 is set to 2 GHz or less. In this case, since the pass band of the waveform shaping unit 90 is equal to or less than the inverse of the rising time and falling time of the EOM drive pulse signal S12 (10 GHz), the EOM drive pulse signal S12 is slowed down to become the rising time of the shaping signal S15. The fall time is 500 ps, and the pulse width (half width) of the shaping signal S15 is 500 ps.

FIG. 3 (f) shows the waveform of the EOM drive pulse signal S12 when the pulse width w1 is 1 ns, and FIG. 3 (c) shows the waveform shaping when the pulse width w1 of the EOM drive pulse signal S12 is 1 ns. It is a waveform of the shaping signal S15 when the pass band of the part 90 is set to 1 GHz or less. In this case, since the pass band of the waveform shaping unit 90 is equal to or less than the inverse of the rising time and falling time of the EOM drive pulse signal S12 (10 GHz), the EOM drive pulse signal S12 is slowed down to become the rising time of the shaping signal S15. The fall time is 1 ns, and the pulse width (half width) of the shaping signal S15 is 1 ns. As shown in FIG. 3, the waveform of the shaping signal S15 has a shape close to a bell-shaped Gaussian shape even if the pulse width w1 of the EOM drive pulse signal S12 is changed.

The EOM drive unit 22 outputs the EOM drive signal S22, which is a signal corresponding to the shaping signal S15, to the EOM 12, and drives the EOM 12 by pulse modulation. In the example shown in FIG. 2, the pulse width of the EOM drive signal S22 when the LD 11 is on is smaller than the pulse width of the LD drive signal S21. Therefore, the laser beam L1 becomes a pulsed laser beam obtained by pulse-modulating the laser beam L01 by the EOM 12 and cutting out the pulse width of the EOM drive signal S22.

The laser beam L1 cut out by the EOM 12 is amplified by the preamplifier 40. In the preamplifier 40 in the state of population inversion, when the cut out laser beam L1 is input, the electrons at the upper level decrease from the peak of the bell-shaped waveform of the laser beam L1, but the laser beam L1 Since the intensity waveform is bell-shaped, the intensity of the laser beam L1 also decreases after the peak. Further, since the waveform of the intensity of the laser beam L1 is bell-shaped, the time from the rising edge of the waveform to the peak is relatively long. Therefore, the waveform of the intensity of the laser beam L2 output from the preamplifier 40 corresponds to the waveform of the laser beam L1, and the waveform of the laser beam L1 can be maintained in the laser beam L2.

The timing of the LD drive signal S21 and the EOM drive signal S22 is adjusted so that the EOM 12 is in the on state at least while the LD 11 is in the on state. Specifically, the EOM 12 is in the on state while the LD 11 is in the on state around the times t1 and t2. As a result, the laser light L1 (EOM light output) output from the EOM 12 becomes a pulse laser light composed of an optical pulse train having a repetition frequency of f1 and a pulse width of the pulse width of the EOM drive signal S22. The repetition frequency f1 of the LD drive pulse signal S11 and the pulse width of the EOM drive pulse signal S12 are set to desired values for the laser beam L1 by the user's setting or the like.

[Modification example]
Although the embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment and can be implemented in various other embodiments. For example, the present invention may be carried out by modifying the above-described embodiment as follows. The above-described embodiment and the following modifications may be combined. The present invention also includes a configuration in which the components of each of the above-described embodiments and modifications are appropriately combined. Further, further effects and modifications can be easily derived by those skilled in the art. Therefore, the broader aspect of the present invention is not limited to the above-described embodiment or modification, and various modifications can be made.

FIG. 4 is a block diagram of the pulse laser device 100B according to the modified example. In the pulse laser device 100B, the position of the waveform shaping unit 90, the signal received by the EOM driving unit 22, the signal received by the waveform shaping unit 90, and the signal received by the EOM 12 are different from the above-described embodiment, and other configurations are the same as those of the embodiment. Is. In the following description, the same components as those in the embodiment will be omitted from the description by using the same reference numerals in the modified examples, and the differences from the embodiments will be described.

FIG. 5 is a diagram showing an example of a time chart of various signals and optical outputs in the pulse laser apparatus 100B. In FIG. 5, the laser beam L01 and the laser beam L1 show intensity waveforms. In the modification, the LD drive pulse signal S11 output by the control unit 30 to the LD drive unit 21, the LD drive signal S21 output by the LD drive unit 21 to the LD11, the laser beam L01 output by the LD11, and the control unit 30 are EOM-driven. The EOM drive pulse signal S12 output to the unit 22 is the same as that of the above-described embodiment.

The control unit 30 outputs the EOM drive pulse signal S12 to the EOM drive unit 22. The EOM drive unit 22 outputs the EOM drive signal S22B, which is a signal corresponding to the EOM drive pulse signal S12, to the waveform shaping unit 90.

The control unit 30 controls the pass band of the waveform shaping unit 90 with the band control signal S16. For example, the control unit 30 controls the pass band with the band control signal S16 to a frequency band equal to or less than the inverse of the pulse width w1 of the EOM drive pulse signal S12, and when the pulse width w1 is 100 ps, the pass band of the waveform shaping unit 90 is set. Set to 10 GHz or less. Further, for example, when the pulse width w1 of the EOM drive pulse signal S12 is 500 ps, the control unit 30 sets the pass band of the waveform shaping unit 90 to 2 GHz or less, and when the pulse width w1 is 1 ns, the passage of the waveform shaping unit 90. Set the band to 1 GHz or less.

The EOM drive signal S22B is waveform-shaped when passing through the waveform shaping unit 90, and is output to the EOM 12 as a shaping signal S15B which is a signal corresponding to the EOM drive signal S22B. Here, the waveform of the shaping signal S15B has a bell shape similar to the waveform of the EOM drive signal S22 of the embodiment, and the rise time, fall time, and pulse width (half width) are the pulse width and waveform of the EOM drive pulse signal S12. It depends on the pass band of the shaping unit 90. The EOM 12 is driven by pulse modulation according to the shaping signal S15B, and the laser beam L01 outputs the pulse-modulated laser beam L1.

In the example shown in FIG. 5, the pulse width of the EOM drive signal S22B when the LD 11 is on is smaller than the pulse width of the LD drive signal S21. Therefore, the laser beam L1 becomes a pulsed laser beam obtained by pulse-modulating the laser beam L01 by the EOM 12 and cutting out the pulse width of the EOM drive signal S22. Also in this modification, since the waveform of the intensity of the laser beam L1 is bell-shaped, the waveform of the intensity of the laser beam L2 output from the preamplifier 40 corresponds to the waveform of the laser beam L1. Can maintain the waveform of the laser beam L1.

In the above configuration, the waveform of the signal after being shaped by the waveform shaping unit 90 is a bell shape, but the waveform after shaping is not limited to the bell shape. For example, the waveform shaping unit 90 may shape the received signal into a waveform that increases to the peak and decreases from the peak, such as a mountain-shaped waveform or a waveform obtained by integrating a rectangular wave.

FIG. 6 is a diagram showing the waveform of the EOM drive pulse signal S12, the waveform of the shaping signal S15 after the EOM drive pulse signal S12 is waveform-shaped by the waveform shaping unit 90, and the rising and falling timings of these signals. be. The waveform after shaping by the waveform shaping unit 90 is a waveform in which the center of the waveform is delayed with respect to the EOM drive pulse signal S12 and the pulse width is widened. The delay at the center of the waveform is about ½ of the pulse width of the EOM drive pulse signal S12. For example, if the pulse width of the EOM drive signal S22 is widened after the falling edge of the LD drive signal S21 in response to the shaping signal S15, the LD drive signal S21 is turned off before the EOM drive signal S22 is turned off. The laser beam L1 does not have a waveform corresponding to the EOM drive signal S22, and the desired laser beam L1 cannot be obtained. In order to prevent such a state, for example, the pulse width of the LD drive signal S21 may be widened according to the pass band of the waveform shaping unit 90. Further, for example, the output timing of the EOM drive pulse signal S12 may be controlled so that the falling edge of the EOM drive signal S22 is before the falling edge of the LD drive signal S21. FIG. 7 is a diagram showing an example of a time chart of various signals and optical outputs when the timing of the EOM drive pulse signal S12 is adjusted. When controlling the output timing of the EOM drive pulse signal S12, as shown in FIG. 7, the EOM drive signal S22 peaks at times t1 and t2, and the laser beams L1 and EOM are driven around the times t1 and t2. It is preferable to control the timing of the EOM drive pulse signal S12 so that the timing of the signal S22 is aligned.

10 Seed light source 11 LD
12 EOM
20 Drive unit 21 LD drive unit 22 EOM drive unit 30 Control unit 40 Pre-amp 50 Booster amplifier 60 Output unit 90 Waveform shaping unit 100, 100B Pulse laser device L01, L1, L2, L3, L4 Laser light S11 LD drive pulse signal S12 EOM Drive pulse signal S15, S15B Formatting signal S16 Band control signal S21 LD drive signal S22, S22B EOM drive signal

Claims (8)

Laser light source and
Electro-optic modulator and
A laser light source drive unit that outputs a laser light source drive signal that drives the laser light source by pulse modulation, and a laser light source drive unit.
An electro-optical modulator drive unit that outputs a modulator drive signal that drives the electro-optical modulator by pulse modulation, and
A control unit that controls the laser light source drive unit and the electro-optical modulator drive unit,
Equipped with
The laser light source outputs pulsed laser light pulse-modulated by the laser light source drive signal.
The electro-optical modulator outputs a pulsed laser beam in which the pulsed laser beam output by the laser light source is further pulse-modulated by the modulator drive signal.
The control unit drives the laser light source so that the pulse modulation for the laser light source and the pulse modulation for the electro-optical modulator are turned on at least while the laser light source is on. Controls the unit and the electro-optical modulator drive unit,
The electro-optical modulator drive unit shapes the waveform of the modulator drive signal into a waveform having a pulse width corresponding to the time width during which the electro-optic modulator is turned on in a predetermined shape.
A pulsed laser device having a variable time width. The control unit outputs a rectangular wave pulse signal that turns on the electro-optical modulator.
The electro-optical modulator drive unit
A waveform shaping unit that shapes the waveform of the pulse signal into a pulse width corresponding to the time width during which the electro-optical modulator is turned on in the predetermined shape.
An amplification unit that amplifies the signal shaped by the waveform shaping unit and outputs it as the modulator drive signal.
The pulse laser apparatus according to claim 1. The pulse laser device according to claim 2, wherein the waveform shaping unit is a band variable filter. The waveform shaping unit shapes the waveform of the pulse signal into a waveform having a pulse width corresponding to the time width in which the electro-optical modulator is turned on and having a longer rise time and fall time than the pulse signal. The pulse laser apparatus according to claim 2 or claim 3. The pulse laser apparatus according to claim 4, wherein the waveform has a Gaussian shape. The pulse laser device according to any one of claims 1 to 5, wherein the pulse width of the pulse laser light further pulse-modulated by the electro-optical modulator is 1 ns or less. The pulse laser apparatus according to any one of claims 1 to 6, further comprising an optical amplifier for amplifying pulse laser light further pulse-modulated by the electro-optical modulator. Equipped with a laser light source and an electro-optical modulator,
The laser light source outputs pulse-modulated pulse laser light, and the electro-optical modulator is a control method for a pulse laser device that outputs pulse laser light obtained by further pulse-modulating the pulse laser light output by the laser light source. And,
The pulse modulation for the laser light source and the pulse modulation for the electro-optical modulator are such that the electro-optical modulator is in the on state at least while the laser light source is in the on state.
The waveform of the signal for turning on the electro-optical modulator is shaped into a waveform having a pulse width corresponding to the time width for turning on the electro-optic modulator in a predetermined shape.
A method for controlling a pulsed laser device having a variable time width.

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