JP7575058B2 - Laser light source device and method for controlling laser light source device - Google Patents

Description

The present invention relates to a laser light source device that outputs pulsed light at a predetermined repetition rate to an external device based on a request signal from the external device, and a method for controlling the laser light source device.

The high peak power pulsed light generated by the laser light source device is suitable for processing various devices such as electronic materials and composite materials by using an external device such as a processing device equipped with a scanning optical system that irradiates the workpiece with the pulsed light.

Taking smartphones as an example, it is used to process many components, such as patterning the ITO (Indium Tin Oxide) that makes up the touch panel, drilling holes in protective glass and substrates, and tuning high-frequency components such as crystal oscillators and antennas.

The pulsed light used in these processing applications must be turned on and off in synchronization with a request signal from an external device, and a pulse width of the order of picoseconds is required to reduce thermal damage to the workpiece. From the perspective of turning on and off pulsed light in synchronization with a request signal from an external device, a Q-switched laser is a candidate, but since its pulse width is long at several nanoseconds, it is difficult to adopt for applications aimed at micromachining. Synchronized lasers have a short pulse width of several picoseconds, but it is similarly difficult to adopt because it is difficult to turn on and off pulsed light in synchronization with a request signal from an external device.

Patent Document 1 discloses a laser light source device including a seed light source that outputs pulsed light by a gain switching method, a fiber amplifier that amplifies the pulsed light output from the seed light source, a solid-state amplifier that amplifies the pulsed light output from the fiber amplifier, and a nonlinear optical element that converts the wavelength of the pulsed light output from the solid-state amplifier and outputs it. The laser light source device includes an optical switch element that is disposed between the fiber amplifier and the solid-state amplifier and allows or blocks the propagation of light from the fiber amplifier to the solid-state amplifier, and a control unit that is configured to generate an output stop state that stops the output of pulsed light from the nonlinear optical element by controlling the optical switch element to block the propagation of light during the output period of the pulsed light from the seed light source and to allow the propagation of light during a period different from the output period of the pulsed light from the seed light source.

According to the laser light source device described in Patent Document 1, it is possible to realize an output stop state in which the output of pulsed light from the nonlinear optical element is stopped by controlling the optical switch element without stopping the seed light source.

In addition, the optical switch element is controlled by the control unit so that light propagation is permitted during a period different from the output period of the pulsed light from the seed light source when the output is stopped, so that spontaneous emission noise generated in the fiber amplifier at the previous stage propagates to the solid-state amplifier at the next stage, and energy is released from the active region of the solid-state amplifier that is excited by the excitation light source. As a result, no giant pulse is generated when transitioning to the output-permitting state thereafter, and no damage is caused to the solid-state amplifier or nonlinear optical element.

WO2015/122375 publication

A laser light source device such as that described in Patent Document 1 generally switches between an output-stopped state and an output-permitted state based on a request signal from an external device, such as a processing device equipped with a scanning optical system.

However, the timing of the pulsed light output from the laser light source device when switching from an output-stopped state to an output-allowed state is not constant, but fluctuates within the range of the repetition period, making it difficult to use for precise micromachining.

For example, if the output timing of the pulsed light varies when irradiating multiple rows with pulsed light, the positions of the start and end points in the row direction will vary, and when processing at high speeds, this variation will become greater, resulting in a decrease in processing quality.

In addition, since the repetition period of the pulsed light output from the laser light source device is configured to be adjustable to a value required by an external device or the object to be processed, it is desirable to always output pulsed light at a constant timing, regardless of the adjustment value of the repetition period, when switching from an output-stopped state to an output-allowed state.

To achieve this, if the seed light source is stopped in the output stop state and controlled to be driven when the state is switched to the output allowable state, pulsed light can be output at a constant timing regardless of the adjustment value of the repetition period. However, because the energy excitation state of the optical amplifier fluctuates between the output stop state and the output allowable state, there is a problem in that the intensity of the pulsed light output from the laser light source device fluctuates when the state is switched to the output allowable state, deteriorating the processing quality of the object to be processed.

In view of the above-mentioned problems, the object of the present invention is to provide a laser light source device and a control method for a laser light source device that can always output pulsed light with stable intensity at a fixed time when the output of pulsed light from the device is temporarily stopped while driving a seed light source and then the output is resumed.

In order to achieve the above-mentioned object, the first characteristic configuration of the laser light source device according to the present invention is a laser light source device that outputs pulsed light to an external device at a predetermined repetition period Tr based on a request signal from the external device, and includes a seed light source that outputs pulsed light by a gain switching method, an optical amplifier that amplifies the pulsed light output from the seed light source, an optical switch element arranged downstream of the optical amplifier, and a control circuit that drives the seed light source at the repetition period Tr and drives the optical switch element based on the request signal, and when the request signal is switched from an off state to an on state, the control circuit is configured to execute output permission control to switch the drive state of the seed light source and switch the optical switch element to the on state so that pulsed light is output from the optical switch element at a timing when a predetermined stable time Ts has elapsed from the on timing of the request signal, and to execute output stop control to continue driving the seed light source and turn off the optical switch element when the request signal is switched from the on state to the off state.

By applying the gain switching method, pulsed light of the picosecond order can be output from the seed light source at any timing, and the control circuit can control the optical switch element placed after the optical amplifier based on a request signal from an external device to allow the pulsed light output from the optical amplifier to be output to the outside, or to stop the output of the pulsed light output from the optical amplifier to the outside.

When the request signal from the external device switches from an off state to an on state, the control circuit executes output allowance control, and pulsed light of stable intensity is output from the optical switch element at a fixed timing regardless of the value of the repetition period Tr, that is, a predetermined stable time Ts has elapsed since the on timing of the request signal. In addition, when the request signal from the external device switches from an on state to an off state, the control circuit executes output stop control, so that the seed light source continues to be driven and the optical switch element is turned off, stopping the output of pulsed light to the outside. At this time, the seed light source continues to be driven as is, so that the seed light source and the optical amplifier are maintained in a stable state.

In the second characteristic configuration, in addition to the first characteristic configuration described above, the control circuit adjusts an adjustment time Tp expressed by the following formula from the on-timing of the request signal in the output allowable control:
Adjustment time Tp=(stable time Ts) MOD (repetition period Tr),
The point is that the driving state of the seed light source is switched at the timing when the time has elapsed.

When the seed light source is driven at a predetermined repetition period Tr, the drive state is switched. For example, when the seed light source is newly driven at a predetermined repetition period Tr from any point within the range of one cycle of the repetition period Tr, the first pulse light is input to the optical amplifier in a state in which the excitation state of the optical amplifier has decreased due to the amplification of the previous pulse light, and it takes time for the intensity of the pulse light to return to a steady state. If this time is the stabilization time Ts, the remainder when (stabilization time Ts) is divided by (repetition period Tr) is calculated as the adjustment time Tp. Therefore, if the drive state of the seed light source is switched at a timing when the adjustment time Tp has elapsed from the on timing of the request signal, the first pulse light will be output with a stable intensity after a certain stabilization time Ts has elapsed regardless of the value of the repetition period Tr.

The third characteristic configuration of the present invention is, in addition to the second characteristic configuration described above, characterized in that the control circuit satisfies the following relational expression at the on timing of the request signal in the output allowable control:
The elapsed time Tc from the immediately preceding drive of the seed light source + the adjustment time Tp ≧ the repetition period Tr,
is satisfied, the seed light source is driven to output a protection pulse at the on timing of the request signal.

When the driving state of the seed light source is switched when the adjustment time Tp and the repetition period Tr are approximately the same time, there is a risk that the pulsed light will not be output for a time equivalent to the repetition period Tr from the output of the pulsed light before switching, and the first pulsed light will be output after two repetition periods Tr have elapsed. In such a case, since the excitation state of the optical amplifier is higher than the steady state, a pulsed light with a higher intensity than the steady state is output, and there is a risk that the processing object irradiated with the pulsed light will be damaged. Therefore, when the relationship of the elapsed time Tc from the previous drive of the seed light source + adjustment time Tp ≧ repetition period Tr is established, the excitation state of the optical amplifier can be stabilized thereafter by driving the seed light source to output a protective pulse at the on timing of the request signal.

The fourth characteristic configuration of the present invention is, in addition to any one of the first to third characteristic configurations described above, in that the stabilization time Ts is set based on the longest period Tr _max within an adjustment range of the repetition period Tr.

If the stabilization time Ts is set based on the longest period Tr _max among the repetition periods Tr that can be adjusted in the laser light source device, pulsed light can be output to the outside at the same timing with any repetition period Tr when the request signal from the external device is switched from the off state to the on state.

The fifth characteristic configuration is that, in addition to any one of the first to fourth characteristic configurations described above, the control circuit turns off the optical switch element a predetermined time after the first pulse light drive signal detected after the request signal is turned off during the output stop control.

When the request signal from an external device is switched to the off state, if the output of the pulse signal and the control to turn off the optical switch element overlap, there is a risk that the final pulse signal may be output, may not be output, or may be output with reduced intensity due to effects such as response delays in the optical switch element. To prepare for such a case, the optical switch element is turned off a predetermined time after the first pulse light drive signal detected after the request signal is turned off, thereby eliminating the effects of response delays in the optical switch element. It goes without saying that the response time of the optical switch element is shorter than the repetition period Tr.

The sixth characteristic configuration is that, in addition to any one of the first to fifth characteristic configurations described above, it further includes a nonlinear optical element that converts the wavelength of the pulsed light output from the optical amplifier and outputs it, and the optical switch element is disposed between the optical amplifier and the nonlinear optical element or after the nonlinear optical element.

By providing a nonlinear optical element that converts the wavelength of the pulsed light output from the optical amplifier and outputs it, it is possible to obtain pulsed light with high energy intensity and a wavelength that provides good processing efficiency. When providing such a nonlinear optical element, an optical switch element can be placed between the optical amplifier and the nonlinear optical element, or after the nonlinear optical element.

A first characteristic configuration of a control method for a laser light source device according to the present invention is a control method for a laser light source device comprising: a seed light source that outputs pulsed light by a gain switching method, an optical amplifier that amplifies the pulsed light output from the seed light source, an optical switch element arranged downstream of the optical amplifier, and a control circuit that drives the seed light source at a predetermined repetition period Tr and drives the optical switch element based on a request signal from an external device, and outputs pulsed light at the repetition period Tr based on the request signal, wherein, when the request signal is switched from an off state to an on state, output allowance control is executed to switch the drive state of the seed light source and to switch the optical switch element to an on state so that pulsed light is output from the optical switch element at a timing when a predetermined stable time Ts has elapsed from the on timing of the request signal, and, when the request signal is switched from an on state to an off state, output stop control is executed to continue driving the seed light source and to turn off the optical switch element.

As described above, according to the present invention, it is possible to provide a laser light source device and a control method for a laser light source device that can always output pulsed light with stable intensity at a fixed time when the output of pulsed light from the device is temporarily stopped while driving the seed light source and then the output is resumed.

Block diagram of the laser light source device 1A to 1D are timing charts of a seed light source and an optical switch element. 13A and 13B are timing charts of a seed light source and an optical switch element according to another embodiment of the present invention. 1A is a characteristic diagram of the peak value of the pulse that varies depending on the timing of switching the driving state of the seed light source when pulse light is output at a repetition period of 600 kHz, and FIG. 1B is a characteristic diagram of the recovery time of the peak value at that time. Explaining the relationship between adjustment time Tp and repetition period Tr FIG. 13 is a block diagram showing a laser light source device according to another embodiment. FIG. 13 is a block diagram showing a laser light source device according to another embodiment.

The following describes an embodiment of a laser light source device and a method for controlling a laser light source device according to the present invention. FIG. 1 shows an example of the configuration of a laser light source device 1 according to the present invention. The laser light source device 1 is a device that outputs laser pulse light (hereinafter simply referred to as "pulse light") to a higher-level system 100, and includes a seed light source 10, an optical amplifier 20, a wavelength conversion element 30, an optical switch element 40, and a control circuit 50.

A distributed feedback laser diode (hereinafter referred to as "DFB laser") that outputs laser light in a single longitudinal mode is used as the seed light source 10, and based on a drive signal output from the control circuit 50 via the driver circuit D1, the DFB laser outputs a single pulse of light or a pulse of light with a desired pulse width of several hundred picoseconds or less in a desired frequency range between 100 kHz and several MHz (e.g., 200 kHz to 3 MHz).

To make the seed light source 10 emit light using the gain switching method, a trigger signal with a predetermined pulse width is output from the control circuit 50 to the driver D1 of the DFB laser. When a pulse current corresponding to the trigger signal is applied from the driver circuit to the DFB laser, relaxation oscillation occurs, and a pulsed laser light is output that consists of only the first wave, which has the highest emission intensity immediately after the start of light emission due to relaxation oscillation, and does not include sub-pulses from the second wave onwards. The gain switching method is a method of generating pulsed light with a short pulse width and high peak power by utilizing such relaxation oscillation.

The optical amplifier 20 comprises two stages of fiber amplifiers and one stage of solid-state amplifier connected in series, and the pulsed light with a wavelength of 1064 nm output from the seed light source 10 is amplified by the two stages of fiber amplifiers 22 and 24, and is further amplified to the desired level by the one stage of solid-state amplifier.

As a fiber amplifier, a rare-earth doped optical fiber such as an ytterbium (Yb) doped fiber amplifier pumped by an excitation light source of a specific wavelength (e.g. 975 nm) is used.

A solid-state laser medium such as an Nd:YVO4 crystal or an Nd:YAG crystal is preferably used as the solid-state amplifier 50. The solid-state laser medium is excited by excitation light output from an excitation light source consisting of a laser diode with an emission wavelength of 808 nm or 888 nm and shaped into a beam by a collimator.

The pulsed light with a pulse energy of several picojoules to several hundred picojoules output from the seed light source 10 is finally amplified by the optical amplifier 20 to a pulsed light with a pulse energy of several tens of microjoules to several tens of millijoules.

The number of fiber amplifiers and solid-state amplifiers is not particularly limited, and may be set appropriately to obtain the desired amplification rate for the pulsed light. For example, three fiber amplifiers may be cascaded, followed by two solid-state amplifiers.

Two types of nonlinear optical elements, an LBO crystal (LiB ₃ O ₅ ) and a CLBO crystal (CsLiB ₆ O ₁₀ ), are used as the wavelength conversion element 30. The pulsed light with a wavelength of 1064 nm output from the seed light source 10 and amplified to a predetermined level by the optical amplifier 20 is wavelength-converted to a wavelength of 532 nm by the LBO crystal (LiB ₃ O ₅ ), and further wavelength-converted to a deep ultraviolet ray with a wavelength of 266 nm by the CLBO crystal (CsLiB ₆ O ₁₀ ). The number and types of nonlinear optical elements can be appropriately selected according to the desired wavelength.

The pulsed light wavelength-converted by the wavelength conversion element 30 is incident on the optical switch element 40, which switches whether or not to output it to the host system 100. An acousto-optic modulator (AOM) is preferably used as the optical switch element 40.

When a gate signal is output from the control circuit 50 to the RF driver D2, a diffraction grating is generated in the crystal that constitutes the acousto-optical element by the transducer (piezoelectric conversion element) to which a high-frequency signal is applied from the RF driver D2, and the pulsed light incident on the acousto-optical element is diffracted in the first order and enters the upper system 100. When the RF driver D2 stops, the pulsed light that entered the acousto-optical element passes through without being diffracted and is attenuated by the optical damper 60.

In addition to an acousto-optic modulator (AOM), it is also possible to use an electro-optic modulator (EOM) that uses intensity modulation by EO modulation to turn light on and off with an electric field, a galvanometer mirror, etc., as the optical switch element 40.

The control circuit 100 can be configured as a circuit block with peripheral circuits in an FPGA (Field Programmable Gate Array), and each block constituting the laser light source device 1 is controlled sequentially by driving a plurality of logic elements based on a program previously stored in memory in the FPGA. Note that in addition to being configured using an FPGA, the control circuit 100 can also be configured with a microcomputer and peripheral circuits such as memory and IO, and can also be configured with a programmable logic controller (PLC).

An example of the host system 100 is a processing device equipped with a scanning optical system 110 that scans and processes the workpiece 200 with deep ultraviolet pulsed light. The control circuit 50 controls the seed light source 10 and the optical switch element 40 so that when a request signal for pulsed light is input from the host system 100, the control circuit 50 outputs pulsed light to the laser light source device 1, and stops outputting the pulsed light when the request signal is turned off. The host system 100 is the external device 100 described below.

The control circuit 50 continuously drives the seed light source 10 intermittently using a gain switching method at a repetition period Tr previously requested by the external device 100. At this time, the light sources for exciting the fiber amplifier and solid-state amplifier that constitute the optical amplifier 20 are always maintained in an on state. The operation of the control circuit 50 is described in detail below.

As shown in FIG. 2(a), when the request signal (EX-REQ) switches from the off state to the on state, the control circuit 50 executes output allowance control to switch the driving state of the seed light source 10 and switch the optical switch element 40 to the on state so that pulsed light is output from the optical switch element 40 at a timing when a predetermined stable time Ts has elapsed from the on timing of the request signal (EX-REQ). As a result, pulsed light of stable intensity is output from the optical switch element 40 at a fixed timing from the on timing of the request signal regardless of the value of the repetition period Tr.

When the request signal switches from the on state to the off state, the control circuit 50 continues to drive the seed light source and executes output stop control to turn off the optical switch element. At this time, the seed light source 10 continues to be driven as is, so that the seed light source 10 and the optical amplifier 20 are maintained in a stable state.

In the output tolerance control, the control circuit 50 switches the drive state of the seed light source 10, which is driven at a predetermined repetition period Tr, when the adjustment time Tp shown in the following formula, that is, the adjustment time Tp = (stable time Ts) MOD (repetition period Tr), has elapsed from the on timing of the request signal.

For example, when the seed light source 10 is driven at a new repetition period Tr from any point within the range of one cycle of the repetition period Tr, the first pulse light is input to the optical amplifier in a state in which the excitation state of the optical amplifier 20 has decreased due to the amplification of the previous pulse light.

Figures 4(a) and (b) show the effects of timing deviations when switching the drive state at the same 600 kHz (represented as "switching" in the figure) for pulsed light with a repetition frequency of 600 kHz from the seed light source 10. It can be seen that the more the drive timing of the pulsed light deviates from the original, the lower the peak value of the pulsed light becomes, and the longer it takes to recover.

As a result, it takes time for the intensity of the pulsed light to return to a steady state. If the time it takes for the intensity of the pulsed light to return to a steady state is called the stabilization time Ts, then the remainder when (stabilization time Ts) is divided by (repetition period Tr) is calculated as the adjustment time Tp.

Figure 5 shows the relationship between the repetition frequency (1/Tr) and the adjustment time Tp. It can be seen that the adjustment time Tp depends on the repetition frequency (1/Tr). Note that the vertical axis of Figure 5 is in units of the operating clock of the control circuit.

Therefore, by switching the driving state of the seed light source 10 when the adjustment time Tp has elapsed since the on timing of the request signal, the first pulse light is output with a stable intensity after a certain stabilization time Ts has elapsed regardless of the value of the repetition period Tr.

The stabilization time Ts is set based on the longest period Tr _max in the adjustable range of the repetition period Tr, and in this embodiment, it is in the range of 2000 nanoseconds to 20000 nanoseconds. If the stabilization time Ts is set based on the longest period Tr _max among the repetition periods Tr that can be adjusted by the laser light source device 1, it is possible to output pulsed light to the outside at the same timing with any repetition period Tr when the request signal from the external device 100 is switched from the off state to the on state.

The control circuit 50 switches the driving state of the seed light source 10 and sets a timer Tad for driving the optical switch element 40 so that pulsed light is output to the external device 100 after the stabilization time Ts has elapsed, and outputs a gate signal to the RF driver D2 when the timer Tad counts up. When the response time (delay time) of the optical switch element 40 is Taod, the value of the timer Tad is determined by the following formula. Note that, at this time, the relationship of repetition period Tr>response time Taod is assumed.
Tad=Ts-Taod

During output stop control, the control circuit 50 turns off the optical switch element 40 after a predetermined time Toff has elapsed from the first pulse light drive signal detected after the request signal is turned off.

When the request signal from the external device 100 is switched to the off state, if the output of the pulse signal and the control to turn off the optical switch element 40 overlap, there is a risk that the final pulse signal may be output, may not be output, or may be output with reduced intensity due to the effects of a response delay that occurs in the optical switch element 40.

To prepare for such a case, the optical switch element 40 is turned off after a predetermined time Toff has elapsed from the first pulse light drive signal detected after the request signal is turned off, thereby eliminating the effects of response delays and the like that occur in the optical switch element 40.

Figure 2(b) also shows a similar timing chart, illustrating an example in which the repeat period Tr is longer than the repeat period Tr in Figure 2(a).

When the difference between the adjustment time Tp and the repetition period Tr becomes less than a predetermined threshold value during output tolerance control, the control circuit 50 drives the seed light source 10 to output a protection pulse at the on timing of the request signal.

In this embodiment, when the adjustment time Tp is equal to or greater than a predetermined ratio of the repetition period Tr, if the following formula, 0.6 x Tr < Tp, is satisfied, switching the drive state of the seed light source 10 may result in no pulsed light being output for a time equivalent to the repetition period Tr from the output of the pulsed light before switching, and the first pulsed light may actually be output after two repetition periods Tr have elapsed. The predetermined ratio may be set appropriately within the range of 0.5 to 1.0.

When the above formula is satisfied, the excitation state of the optical amplifier 20 rises above the steady state, and pulsed light with a higher intensity than that in the steady state is output. As a result, there is a risk of damage to the workpiece irradiated with the pulsed light.

In such a case, the excitation state of the optical amplifier 20 can be reduced by driving the seed light source 10 to output a single protection pulse at the on timing of the request signal, and then the excitation state of the optical amplifier 20 can be stabilized by switching the driving state of the seed light source 10.

However, there is a time difference between the adjustment time Tp calculated by the control circuit 50 based on the repetition period Tr and stabilization time Ts set on the control circuit 50 side, and the detection time of the request signal input from the external device 100 to the control circuit 50. This can cause fluctuations in the previous pulse and the protection pulse, which can cause unstable operation. To eliminate the effect of the time difference, it is necessary to provide a margin in the value of the stabilization time Ts.

Therefore, in the output tolerance control, when the following relationship is satisfied at the on-timing of the request signal, that is, when the elapsed time Tc from the previous seed light drive + adjustment time Tp ≥ repetition period Tr, the control circuit 50 preferably drives the seed light source 10 to output a protection pulse at the on-timing of the request signal, eliminating the need to provide a margin for the value of the stabilization time Ts.

For example, as shown in FIG. 2(c), when Tp≈Tr, if the seed light source 10 is started after the adjustment time Tp has elapsed from the on timing of the request signal, when a time of approximately 2Tr has elapsed since the previous drive of the seed light source 10, the energy accumulated in the optical amplifier 20 during that time becomes excessive, and the time until the steady state is restored becomes longer than the stable time Ts.

In such a case, in order to prevent excessive energy from being excited in the optical amplifier 20, the seed light source 10 is controlled to output a protection pulse when the elapsed time Tc from the previous seed light drive + adjustment time Tp ≥ repetition period Tr is satisfied at the on timing of the request signal.

Figure 2(d) shows an example in which a request signal is input from the external device 100 at the same timing as in Figure 2(c), the request signal is turned off before the stabilization time Ts has elapsed, and then the request signal is input again from the external device 100. Even in this case, the protection pulse is still output.

Figure 3 (a) shows an example in which the control circuit 50 controls to output a pulsed light of a pre-specified number of pulses (8 pulses in this embodiment) after a request signal is input from the external device 100. The optical switch element 40 is turned off after a time of Taod + (8-1) x Tr has elapsed after the drive signal is turned on.

Figure 3(b) shows the control when a request signal is input from the external device 100 and the request signal is turned off while the control circuit 50 is outputting a pulsed light with a pre-specified number of pulses. This is the same as the explanation of Figure 2(a).

In the above embodiment, an example was described in which the optical switch element 40 was placed after the nonlinear optical element (wavelength conversion element 30), but as shown in FIG. 6, the optical switch element 40 may be placed between the optical amplifier 20 and the nonlinear optical element (wavelength conversion element 30).

In the above-mentioned embodiment, the laser light source device 1 is described as having a nonlinear optical element (wavelength conversion element 30) that converts the wavelength of the pulsed light output from the optical amplifier 20 and outputs it. However, as shown in FIG. 7, the output of the optical amplifier 20 may be configured to be output to the external device 100 without using the nonlinear optical element (wavelength conversion element 30).

That is, the laser light source device 1 outputs pulsed light at a predetermined repetition period Tr based on a request signal from an external device 100, and includes a seed light source 10 that outputs pulsed light using a gain switching method, an optical amplifier 20 that amplifies the pulsed light output from the seed light source 10, an optical switch element 40 arranged after the optical amplifier 20, and a control circuit that drives the seed light source 10 at the repetition period Tr and drives the optical switch element 40 based on the request signal, and when the request signal switches from an off state to an on state, the control circuit 50 executes output permission control to switch the drive state of the seed light source and switch the optical switch element to an on state so that pulsed light is output from the optical switch element at a timing when a predetermined stable time Ts has elapsed from the on timing of the request signal, and when the request signal switches from an on state to an off state, it is sufficient that the control circuit 50 is configured to continue driving the seed light source and execute output stop control to turn off the optical switch element.

As described above, the control method for a laser light source device according to the present invention is a control method for a laser light source device that includes a seed light source that outputs pulsed light by a gain switching method, an optical amplifier that amplifies the pulsed light output from the seed light source, an optical switch element disposed downstream of the optical amplifier, and a control circuit that drives the seed light source at a repetition period Tr and drives the optical switch element based on the request signal, and outputs pulsed light to an external device at a predetermined repetition period Tr based on a request signal from the external device, and when the request signal is switched from an off state to an on state, output permission control is executed to switch the drive state of the seed light source and switch the optical switch element to an on state so that pulsed light is output from the optical switch element at a timing when a predetermined stable time Ts has elapsed from the on timing of the request signal, and when the request signal is switched from an on state to an off state, output stop control is executed to continue driving the seed light source and turn off the optical switch element.

The above-mentioned embodiments are each an explanation of one embodiment of the present invention, and the scope of the present invention is not limited by the description. Furthermore, it goes without saying that the specific circuit configuration of each part and the optical elements used in the circuit can be appropriately selected or modified within the scope of the effects of the present invention.

1: Laser light source device 10: Seed light source 20: Optical amplifier 30: Wavelength conversion element (nonlinear optical element)
40: Optical switch element 50: Control circuit 100: Upper system (external device)
110: Scanning optical system 200: Workpiece

Claims (7)

A laser light source device that outputs pulsed light at a predetermined repetition period Tr based on a request signal from an external device,
a seed light source that outputs pulsed light by a gain switching method, an optical amplifier that amplifies the pulsed light output from the seed light source, an optical switch element disposed in a stage subsequent to the optical amplifier, and a control circuit that drives the seed light source at the repetition period Tr and drives the optical switch element based on the request signal,
The control circuit is configured to, when the request signal is switched from an off state to an on state, execute output allowance control to switch the drive state of the seed light source and switch the optical switch element to an on state so that pulsed light is output from the optical switch element at a timing when a predetermined stable time Ts has elapsed from the on timing of the request signal, and to continue driving the seed light source and execute output stop control to turn off the optical switch element when the request signal is switched from the on state to the off state. The control circuit, in the output allowable control, adjusts a time Tp from the on-timing of the request signal as shown in the following formula:
Adjustment time Tp=(stable time Ts) MOD (repetition period Tr),
The laser light source device according to claim 1 , wherein the driving state of the seed light source is switched at a timing when time t has elapsed. The control circuit, in the output allowable control, satisfies the following relational expression at the on timing of the request signal:
The elapsed time Tc from the immediately preceding drive of the seed light source + the adjustment time Tp ≧ the repetition period Tr,
3. The laser light source device according to claim 2, wherein when the above expression is satisfied, the seed light source is driven to output a protection pulse at an ON timing of the request signal. 4. The laser light source device according to claim 1, wherein the stabilization time Ts is set based on a longest period Tr _max within an adjustment range of the repetition period Tr. The laser light source device according to any one of claims 1 to 4, wherein the control circuit turns off the optical switch element a predetermined time after the first pulse light drive signal detected after the request signal is turned off during the output stop control. a nonlinear optical element that converts the wavelength of the pulsed light output from the optical amplifier and outputs the converted light,
6. The laser light source device according to claim 1, wherein the optical switch element is disposed between the optical amplifier and the nonlinear optical element or in a stage subsequent to the nonlinear optical element. 1. A control method for a laser light source device comprising: a seed light source that outputs pulsed light by a gain switching method; an optical amplifier that amplifies the pulsed light output from the seed light source; an optical switch element disposed in a stage subsequent to the optical amplifier; and a control circuit that drives the seed light source at a predetermined repetition period Tr and drives the optical switch element based on a request signal from an external device , the control method comprising the steps of:
when the request signal is switched from an off state to an on state, an output permission control is executed to switch a driving state of the seed light source and to switch the optical switch element to an on state so that pulsed light is output from the optical switch element at a timing when a predetermined stable time Ts has elapsed from the on timing of the request signal;
The control method for a laser light source device, when the request signal is switched from an on state to an off state, executes output stop control to continue driving the seed light source and turn off the optical switch element.

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