TWI589080B - Laser device and laser processing machine - Google Patents

Description

Laser device and laser processing machine

The present invention relates to a laser device and a laser processing machine using the same, which optically amplifies light output from a seed light source and outputs high peak power. The pulse of the light.

Fine laser processing using lasers, such as perforation of small diameters, marking, etc., is effective in generating a laser having high pulse energy with high peak power. Further, it is desirable to independently control the pulse frequency, the pulse width, the pulse peak power, and the like in a wide range of laser devices in accordance with processing requirements of materials to be processed, apertures after processing, and hole depth.

For a conventional laser light source that outputs light of high pulse energy with high peak power, a solid-state laser Q switch (Q) containing a laser medium such as Nd:YAG crystal, Nd:YVO ₄ crystal or the like is known. -switch) Oscillator. Although the solid-state laser Q-switched oscillator derives high-pulse energy laser light directly from the oscillator at high peak power, the repetition frequency and pulse width of the output pulse can only be controlled within a limited range.

In addition, it outputs high pulse energy as high peak power. Another configuration of a laser light source of a quantity of light is known as an oscillator having a laser light that generates relatively weak power as a seed light, and an MOPA (Master Oscillator) for amplifying an optical light from a seed light of an oscillator. And Power Amplifier, the main oscillator with power amplifier) laser device. For example, a laser device using a semiconductor laser (LD) as a seed light source and amplified by a fiber amplifier is proposed. By using a semiconductor laser as a seed light source, the current injected into the semiconductor laser is controlled, whereby the repetition frequency and pulse width of the output pulse can be controlled over a wide range.

For example, Patent Document 1 is directed to a laser system in which a pulse burst light output from a seed light source is amplified in an optical amplifier by changing a pulse between a pulse and a pulse. The power of the seed source is used to control the peak power or pulse energy of the amplified individual pulsed light while maintaining the excitation power of the optical amplifier. Further, Patent Document 2 is a laser light source device including a fiber amplifier, a semiconductor laser 2 as a seed light source, and a semiconductor laser as an excitation light source, and the semiconductor laser system of the seed light source uses pulsed light during main illumination. The seed light is emitted, and during the preliminary irradiation, the power is smaller than the peak power of the pulsed light, and substantially continuous light is emitted as the seed light, thereby obtaining a pulse having a peak power desired at the start of the emission. Light.

[Previous Technical Literature]

Patent literature:

Patent Document 1: Japanese Special Table 2013-500583

Patent Document 2: Japanese Laid-Open Patent Publication No. 2010-171131

When the seed light is amplified by the fiber amplifier, when the amplified peak power is increased, there is an undesirable nonlinear phenomenon that causes stimulated Raman scattering, self-phase modulation, etc., or damage of the optical fiber. situation. The peak power that begins to produce a nonlinear phenomenon is usually limited depending on the core diameter and length of the fiber used. Since shortening the optical fiber means shortening the amplifying medium, the optical fiber shortening system has a certain limit while maintaining the amplification factor. When the core diameter of the optical fiber becomes large, it is known that the higher peak power does not cause nonlinear phenomena and the optical fiber is damaged, but it is easy to deteriorate the lateral mode of the amplified laser light. . In order to prevent the lateral mode of the laser light from deteriorating and to obtain a higher peak power, it is conceivable to add an optical amplifier that does not propagate the waveguide path in the laser medium, that is, a non-waveguide. A type of optical amplifier, that is, an optical amplifier having an amplifying medium having a thermal lens function. When the amplified light is not propagated in the optical path of the optical amplifier, even if the cross-sectional area of the amplified light is large, the lateral mode of the laser is not easily deteriorated, and the beam quality can be maintained while maintaining excellent beam quality. , zoom to high peak power.

In the optical amplifier of the non-waveguide type, that is, an optical amplifier having an amplifying medium having a thermal lens function, for example, a light using a rod-shaped Nd:YAG crystal or a Nd:YVO ₄ crystal can be used. Amplifier. However, in the optical amplifier described above, it is known that when the generated heat varies, there is a phenomenon in which the characteristics of the thermal lens are changed and the amplified laser beam propagates.

According to Patent Document 1, when the output power of the seed light source is changed while the excitation power of the optical amplifier is kept constant, and the peak power or pulse energy of the amplified pulse is controlled, the average power after amplification is changed. The situation. However, the average power described therein refers to the power at which the instantaneous frequency is averaged over a period of time that is longer than the interval between the pulse and the pulse in the burst burst. In addition, the pulse bursts described herein are not only continuous pulses having the same waveform, but may include a plurality of pulses, or may be various pulse waveforms. As described above, it is conceivable that when there is a non-waveguide type optical amplifier in the latter stage of the optical amplifier, the average power of the amplified light incident on the optical amplifier in the latter stage is different, so that the amplified optical light is taken out from the optical amplifier in the latter stage. The power is varied, and the heat generated by the optical amplifier in the latter stage is varied, whereby the characteristics of the thermal lens are changed, and the amplified laser beam propagates to cause a change.

An object of the present invention is to provide a laser device and a laser processing machine using the same, wherein even if a non-waveguide type optical amplifier is used, that is, an optical amplifier having an amplifying medium having a thermal lens function is used, It is also possible to control the peak power or pulse energy of the pulsed light to a wide range while suppressing the change in the characteristics of the thermal lens.

In order to achieve the above object, the laser device of the present invention Having a seed light source for outputting light; a front optical amplifier for optically amplifying light output from the seed light source; and a post optical amplifier for optically outputting light output from the front optical amplifier Zooming in and including an amplifying medium having a thermal lens function; a power monitor portion measuring an average power of light outputted from the front optical amplifier; and a seed light source driver driving the seed light source; a front optical amplifier driver driving the front optical amplifier; and a control unit for controlling the seed light source driver and the front optical amplifier driver; wherein the control unit controls the seed light source through the seed light source driver to cause the seed light source to be controlled Selectively outputting continuous light or a plurality of pulses, and the control unit controls the gain of the front optical amplifier by the front optical amplifier driver based on the measurement result of the power monitor unit, and the front portion is controlled from the front The average power of the light output by the optical amplifier can be fixed.

Further, the laser device of the present invention comprises: a seed light source for outputting light; a front optical amplifier for optically amplifying light output from the seed light source; and a rear optical amplifier for front-end optical amplifier Light output by an optical amplifier Optically amplified, and comprising an amplifying medium having thermal lens efficiency; a power monitor unit for measuring an average power of light outputted from the pre-amplifier; a seed light source driver for driving the seed light source; a rear light An amplifier driver for driving a post-optical amplifier; and a control unit for controlling the seed light source driver and the post-optical amplifier driver; wherein the control unit controls the seed light source through the seed light source driver to selectively Outputting a continuous light or a plurality of pulses, the control unit controls the gain of the post-optical amplifier through the post-optical amplifier driver based on the measurement result of the power monitor unit, and the post-optical amplifier The propagation state of the beam becomes fixed.

Further, the laser device of the present invention comprises: a seed light source for outputting light; a front optical amplifier for optically amplifying light output from the seed light source; and a rear optical amplifier for front-end optical amplifier The light output by the optical amplifier is optically amplified, and includes an amplifying medium having a thermal lens function; the beam monitor portion is a beam diameter of a beam of light output from the rear optical amplifier; the seed light source driver is Driving the aforementioned seed light source; a post-optical amplifier driver driving the aforementioned post-amplifier; The control unit controls the seed light source driver and the post-optical amplifier driver; the control unit controls the seed light source through the seed light source driver to selectively output continuous light or a plurality of pulses, and the control unit Controlling the gain of the front optical amplifier through the front optical amplifier driver, or controlling the gain of the rear optical amplifier through the rear optical amplifier driver, so that the beam diameter calculated according to the beam monitor portion is not Will change.

In the present invention, the seed light source is preferably a semiconductor laser.

In the present invention, the front optical amplifier preferably includes an optical fiber type amplifying medium and an excitation light source for supplying excitation light to the optical fiber type amplifying medium, and the control unit controls the excitation light power and the excitation light of the front optical amplifier. At least one of the wavelengths.

In the present invention, the post-optical amplifier preferably includes a columnar amplifying medium having a thermal lens function and an excitation light source for supplying excitation light to the columnar amplifying medium.

In the present invention, the post-optical amplifier preferably includes a columnar amplifying medium having a thermal lens function and an excitation light source for supplying excitation light to the columnar amplifying medium, and the control unit controls the excitation of the post-optical amplifier. At least one of optical power and excitation light wavelength.

In the present invention, the pre-optical amplifier preferably includes a fiber-type amplifying medium and excitation light for supplying excitation light to the fiber-type amplifying medium. The source is ideal.

In the present invention, preferably after the aforementioned post-amplifier, a wavelength converter is included.

Further, the laser processing machine of the present invention includes: the above-described laser device; a collecting optical system for collecting a laser beam output from the laser device; and a scanning mechanism for collecting laser light The beam and the workpiece are scanned relative to each other.

In the present invention, the wavelength of the aforementioned laser beam is preferably in the ultraviolet region.

According to the present invention, by controlling the gain of the pre-amplifier, the average power of the light output from the pre-amplifier is fixed, thereby suppressing even if the waveform of the light output from the seed source changes. The characteristic change of the thermal lens of the rear optical amplifier. As a result, the peak power or pulse energy of the pulsed light can be controlled over a wide range without changing the propagation of the output beam.

Further, according to the present invention, by controlling the gain of the post-amplifier, the thermal lens of the post-amplifier is fixed, whereby the post-amplifier can be suppressed even when the waveform of the light output from the seed source is changed. The characteristics of the thermal lens change. As a result, the peak power or pulse energy of the pulsed light can be controlled over a wide range without changing the propagation of the output beam.

Further, according to the present invention, by controlling the pre-amplifier Or the gain of the post-amplifier, so that the beam diameter of the beam of light output from the post-amplifier does not change, thereby suppressing the backlight after the waveform of the light output by the seed source changes. The characteristic change of the thermal lens of the amplifier. As a result, the peak power or pulse energy of the pulsed light can be controlled over a wide range without changing the propagation of the output beam.

1‧‧‧ Seed light source

2‧‧‧Control Department

3‧‧‧Seed light source driver

4‧‧‧Front optical amplifier driver

5‧‧‧ Output extraction means

6, 8‧ ‧ light

7‧‧‧Power monitor circuit

9‧‧‧ Rear Optical Amplifier Driver

10‧‧‧ Beam extraction means

11‧‧‧ Beam Monitor

100‧‧‧ Laser device

110‧‧‧front optical amplifier

120‧‧‧ rear optical amplifier

130‧‧‧wavelength converter

111‧‧‧Semiconductor laser

112‧‧‧ combiner

113‧‧‧Fiber type amplifying medium

121a, 121b‧‧‧ dichroic mirror

122‧‧‧Amplification medium

123a, 123b‧‧‧ excitation light source

124a to 124d‧‧‧Transmission optical system

130‧‧‧wavelength converter

131, 133‧‧ lens

132‧‧‧ wavelength conversion components

135‧‧‧wavelength selection component

201‧‧‧ Beam adjustment optical system

202‧‧‧Light guide mirror

203‧‧‧ Concentrating lens

204‧‧‧Base table

205‧‧‧Laser beam

206‧‧‧Processed objects

207‧‧‧ pedestal scanning direction

208‧‧‧Mask holes

Lambda1 to lambda3‧‧‧beam

B1, B2‧‧‧ Beam Propagation

BM‧‧‧ Beam Monitor Department

PM‧‧‧Power Monitor Department

Fig. 1 is a view showing the configuration of a laser device according to Embodiments 1 and 3 of the present invention.

Fig. 2 is a view showing a configuration of an example of the front optical amplifier 110.

Fig. 3 is a view showing a configuration of an example of the rear optical amplifier 120.

Fig. 4 (a) to (d) show the instantaneous power of the output of the seed light source, the excitation power of the preamplifier, the instantaneous power after the preamplifier, and the time variation of the average power after the preamplifier. An example of a graph.

Fig. 5 (a) to (d) are comparative examples, and show that the instantaneous power of the seed light source, the excitation power of the preamplifier, and the time after the amplified power are fixed when the excitation power of the front optical amplifier is fixed. A graph of an example.

Fig. 6 is a graph showing an example of the relationship between the average power of the signal light incident on the post-amplifier and the power that can be taken out from the post-amplifier.

Fig. 7 is an explanatory view showing an example of a change in beam propagation of signal light of a change in a thermal lens of a magnifying medium.

Figure 8 shows the peak power of the fundamental wave in the second harmonic generation. A graph showing an example of the relationship between the average power after wavelength conversion.

Fig. 9 is a view showing a configuration of an example of the wavelength converter 130.

Fig. 10 is a view showing the configuration of a laser device according to Embodiments 2 and 4 of the present invention.

Fig. 11 is a graph showing the absorption spectrum of Yb (镱).

Fig. 12 is a view showing the configuration of a laser device according to a fifth embodiment of the present invention.

Figure 13 is a view showing the configuration of a laser processing machine according to a sixth embodiment of the present invention.

This patent application is based on Japanese Patent Application No. 2014-175240, filed on Jan. 29,,,,,,,,,,,,,,,,,,,

Hereinafter, the best mode will be described with reference to the drawings.

Embodiment 1

Fig. 1 is a view showing the configuration of a laser device according to a first embodiment of the present invention. The laser device 100 includes a seed light source 1, a front optical amplifier 110, a rear optical amplifier 120, a wavelength converter 130, a control unit 2, a seed light source driver 3, a front optical amplifier driver 4, and a rear optical amplifier driver 9. And the power monitor unit PM and the like. Further, although not specifically shown, the laser device 100 may include an optical isolator for controlling the folded light and a lens and a mirror for transmitting the optical signal on the path through which the optical signal passes. Such as the transmission of optical systems and the like.

The seed light source 1 is driven by the seed light source driver 3 to output seed light. The seed light source 1 is preferably composed of a semiconductor laser capable of controlling the repetition frequency and/or the pulse width of the output pulse over a wide range, for example, a distributed feedback type (DFB) laser or a distributed reflection diffraction (Bragg) Type (DBR) lasers, Fabry-Perot type (FP) lasers, external cavity type lasers, and vertical resonator surface emitting lasers (VCSELs). An example of the light emission wavelength of the seed light source 1 is 1064 nm, but it is not limited to this value, and may be another wavelength. The seed light source 1 may be a wavelength-variable laser that changes the light-emitting wavelength by structural control of an external resonator or the like or external temperature control.

The front optical amplifier 110 is optically coupled to the seed light source 1, is driven by the front optical amplifier driver 4, and optically amplifies the light output from the seed light source 1.

Fig. 2 is a view showing a configuration of an example of the front optical amplifier 110. The pre-amplifier 110 includes: a fiber-type amplifying medium 113; a semiconductor laser 111 for supplying excitation light to the fiber-type amplifying medium 113; and a combiner 112 for introducing excitation light to the fiber-type amplifying medium 113 .

The optical fiber type amplifying medium 113 is a waveguide type that allows waveguide light to propagate through a waveguide, and does not require a thermal lens or can be amplified without being affected by a thermal lens, and a rare earth element is added to a core portion of a glass optical fiber. For example, it is composed of Yb (镱), Er (铒), Nd (钕), Tm (銩), Ho (boron), Pr (鐠), and the like. The optical fiber type amplifying medium 113 can also be configured as a double clad fiber and/or a polarization maintaining fiber. Again, Figure 2 Although the optical fiber type amplifying medium 113 of one segment is exemplified, a configuration of a plurality of fiber-optic amplifying media 113 of a plurality of stages may be employed. In addition, although FIG. 2 is a front-end optical amplifier 110 exemplifying a section, a set of a plurality of semiconductor lasers 111, a combiner 112, and a fiber-type amplifying medium 113 may be used in series as the pre-amplifier 110. And constitute.

The control unit 2 changes the excitation light power of the semiconductor laser 111 through the front optical amplifier driver 4, whereby the gain of the front optical amplifier 110 can be controlled.

Returning to Fig. 1, the power monitor unit PM includes an output extraction means 5 for extracting one of the outputs of the front optical amplifier 110, and a power monitor circuit 7 for measuring the output by the output extraction means 5. The average power of the light 6. The output extraction means 5 is, for example, a partial reflection mirror that reflects a part of light, and a fiber coupler that extracts only a part of light, and an example thereof is an output of the extraction front optical amplifier 110. %degree. The power monitor circuit 7 includes an element that converts the extracted light into an electrical signal, such as a thermopile or a photodiode, and a low-pass filter, etc., measured from the front light. The average power of the light output from the amplifier 110 is transmitted to the control unit 2.

The rear optical amplifier 120 is driven by the post optical amplifier driver 9 and is used to optically amplify the light 8 output from the pre-optical amplifier 110 and passing through the power monitor unit PM. The rear optical amplifier 120 is an optical amplifier that does not perform waveguide path propagation in the laser medium, that is, a non-waveguide type optical amplifier, in order to Suppressing the occurrence of non-linear phenomena such as stimulated Raman scattering (SRS), self-phase modulation (SPM), and optical damage of the exit end face of the amplifier, and constituting the amplified light compared to the former The optical amplifier 110 can be injected with a large cross-sectional area.

Fig. 3 is a view showing a configuration of an example of the rear optical amplifier 120. The rear optical amplifier 120 includes an amplifying medium 122, dichroic spectroscopic mirrors 121a and 121b, transmission optical systems 124a, 124b, 124c, and 124d, and excitation light sources 123a and 123b.

The amplifying medium 122 is formed into a non-waveguide type in which the amplified light does not propagate in a waveguide path, that is, a configuration having an effect of a thermal lens, for example, a columnar or rod-shaped shape having a column, a corner, or the like, and for example An element such as Nd, Yb, Er, Tm, Ho, Pr, or Ti is added to an optical crystal such as YAG (yttrium aluminum garnet), YVO ₄ , GdVO ₄ , sapphire, or glass, or an optical glass. The side of the amplifying medium 122 is provided with a direct or indirect cooling mechanism for cooling. The dichroic mirrors 121a and 121b are configured to reflect the wavelength of the amplified light 8 and to transmit the wavelength of the excitation light.

The excitation light sources 123a, 123b are, for example, semiconductor lasers, solid lasers, etc., and are used to supply excitation light from both ends of the amplification medium 122, respectively. The wavelength of the excitation light is set in accordance with the absorption wavelength of the amplification medium 122. For example, when the amplification medium 122 is Nd:YVO ₄ , it is set to, for example, 808 nm, 880 nm, 888 nm, 914 nm or the like. The transfer optical systems 124a to 124d include lenses, mirrors, and the like, and transmit excitation light from the excitation light sources 123a and 123b to the amplification medium 122.

Regarding the operation, the light 8 output from the pre-amplifier 110 is reflected by the dichroic mirror 121a, amplified by the amplification of the medium 122, and then reflected by the dichroic mirror 121b, and is output toward the rear stage. . When the amplifying medium 122 generates heat by absorbing the excitation light output from the excitation light sources 123a and 123b, a thermal lens is formed in accordance with the distribution of the heat. When the intensity of the aforementioned thermal lens is varied, the amplified beam propagates.

Further, although the third embodiment is an amplifying medium 122 exemplified in a section, it may be configured by forming a plurality of enlarged mediums 122 in series. Further, although FIG. 3 illustrates a post-stage optical amplifier 120, a plurality of sections may be connected in series to the dichroic mirrors 121a and 121b, the amplifying medium 122, the excitation light sources 123a and 123b, and the transmission optical systems 124a to 124d. The components are constructed as a post-amplifier 120.

Returning to Fig. 1, the wavelength converter 130 includes, for example, a nonlinear optical crystal or the like, and has a function of converting the wavelength of light output from the post-optical amplifier 120 into another wavelength. The aforementioned wavelength conversion is, for example, second harmonic generation, sum frequency generation, difference frequency generation, parametric oscillation, or the like. The wavelength converter 130 can be omitted when wavelength conversion is not required.

Then all the actions will be explained. The control unit 2 controls the seed light source 1 to switch between the CW mode and the pulse burst mode through the seed light source driver 3, so that the seed light source 1 can selectively output continuous light (CW) or pulse burst. The pulse burst system can control the power between the pulses and pulses in the burst burst to zero, or a value greater than zero below the peak power of the pulse. In addition, It can also control the power at CW.

As described in Patent Document 1, in the on-and-off transition of the pulse output, the power of the CW of the seed light before the output pulse burst is adjusted, whereby the pulse bundle included in the amplifier can be The peak power of all pulses generated is nominally fixed. Further, during the period between the pulse and the pulse in the burst, the peak power of the amplified individual pulses can be controlled by changing the power of the seed source. On the other hand, the excitation power of the amplifier is fixed, the CW mode and the pulse mode are switched, or the power of the seed light source between the pulse and the pulse in the pulse burst is changed, thereby making the output waveform of the seed light source The change system has a phenomenon that causes the average power after the amplifier to change. The configuration of Patent Document 1 can control the peak power of the pulse after the amplifier by adjusting the power at the CW of the seed light or the power between the pulse and the pulse in the burst, but the excitation power of the amplifier is When fixed, it is also impossible to control the average output after amplification.

In particular, when the optical amplifier (the rear optical amplifier 120) of the second stage exists after the optical amplifier (front optical amplifier 110) of the first stage, when the average power incident on the rear optical amplifier changes, Therefore, the power used for the amplification of the laser light in the post-amplifier is changed, so that the heat generated by the post-amplifier is changed. In this case, the post-amplifier is a non-waveguide type that does not perform waveguide path propagation, that is, when an amplifying medium having a thermal lens is included, when the heat generated by the post-amplifier changes, the post-amplifier is made. The intensity of the thermal lens changes and causes a change in the beam propagation after the post-amplifier.

In the present embodiment, the control unit 2 changes the excitation light power of the semiconductor laser 111 by the front optical amplifier driver 4 based on the measurement result of the power monitor unit PM, and feeds back the control front light. The gain of the amplifier 110 does not cause a change in the average power after the pre-amplifier 110. Accordingly, even if the power of the seed light source 1 changes in time, the average power of the pre-optical amplifier 110 can be kept constant. As a result, the beam propagation after the post-optical amplifier 120 is not changed, and the peak power or pulse energy of the pulse can be controlled over a wide range.

4(a) to (d) show the instantaneous power of the output of the seed light source 1, the excitation power of the front optical amplifier 110, the instantaneous power after the front optical amplifier 110, and the average after the front optical amplifier 110, respectively. A graph of one of the time variations in power. Moreover, since the interval between the pulse and the pulse in the burst burst is typically a very long time of about 1 μs to 1 ms with respect to a typical pulse width of about 100 ps to 100 ns, in order to facilitate understanding, The interval between pulses and pulses is expressed in terms of compression. In addition, the power of the CW with respect to the peak power of the pulse, and the power between the pulse and the pulse are also expressed in an exaggerated manner for the purpose of promoting understanding.

In Fig. 4(a), the power of the CW before the burst burst is adjusted to the peak power of the pulse after the pre-amplifier 110 is nominally fixed. Therefore, the power at the CW of the seed light source 1 varies with the magnitude of the amplified peak power in the subsequent bursts. Therefore, when the excitation power of the front optical amplifier 110 is fixed, the average power after amplification at the CW changes. Good for the front optical amplifier 110 The average power remains fixed in response to the power of the seed source 1 to cause a change in the excitation power of the pre-amplifier.

In addition, the power between the pulse and the pulse in the burst is determined based on the peak power of the amplified pulse. Therefore, when the excitation power of the front optical amplifier 110 is fixed, the peak power of the amplified pulse can be changed, but the average power after amplification cannot be controlled.

Therefore, the instantaneous power of the seed light is as shown in Fig. 4(a), causing a change in the power between the pulse and the pulse in the CW and the burst burst, or in the burst burst, and further as shown in Fig. 4(b) before the control. The excitation power of the optical amplifier 110 is set. Accordingly, the peak power of the pulse after the front optical amplifier 110 can be controlled as shown in Fig. 4(c), and the average power after the front optical amplifier 110 is kept constant as shown in Fig. 4(d). As a result, the characteristics of the thermal lens of the post-amplifier 120 are substantially unchanged, and the beam propagation after the post-amplifier 120 is substantially unchanged.

Fig. 5 is a graph showing an example of temporal changes in the instantaneous power of the seed light source 1, the excitation power of the front optical amplifier 110, and the amplified power when the excitation power of the front optical amplifier 110 is fixed. As shown in Fig. 5(a), the instantaneous power of the seed light source 1 is changed, and as shown in Fig. 5(b), when the excitation power of the front optical amplifier 110 is kept constant, as shown in Fig. 5(c), The peak power of the pulse after the front optical amplifier 110 is controlled. However, as shown in Fig. 5(d), it can be seen that the average power of the front optical amplifier 110 changes. Such a change in the average power is as described above, forming a change in the thermal lens that causes the post-optical amplifier 120, and causing a change in the beam propagation after the post-amplifier 120.

In addition, in the fourth and fifth figures, the seed light source 1 outputs two types of pulse bursts, but one type or three or more types of burst bursts can be output. In addition, the power between the pulses and pulses in the pulse burst can also vary in each pulse.

Fig. 6 is a graph showing an example of the relationship between the average power of the signal light incident on the rear optical amplifier 120 and the power that can be taken out from the post-optical amplifier 120. It can be seen that when the average power incident on the post-optical amplifier 120 becomes large, the power that can be taken out from the post-amplifier 120 is saturated. The average power injected into the post-amplifier 120 becomes smaller, and the power extracted from the post-amplifier 120 is not saturated, that is, when used in an unsaturated region, relative to the incident optical amplifier 120. The change in the average power produces a large change in the amount of heat generated, so that the effect of the present invention is more remarkable.

Fig. 7 is an explanatory view showing an example of a change in beam propagation of signal light of a change in a thermal lens of a magnifying medium. The solid line indicates the change of the thermal lens, and the broken line indicates the change of the thermal lens. When a heat lens of a certain intensity is formed by heat generated by light absorption in the inside of the amplifying medium 122, the light beam that has passed through the amplifying medium 122 propagates as the light beam B1. Thereafter, the power of the light emitted from the front optical amplifier 110 is changed, whereby the amount of heat generated in the amplifying medium 122 of the post optical amplifier 120 is changed. For example, when the intensity of the thermal lens of the amplifying medium 122 is changed by 5%, the beam propagates in the manner of beam propagation B2. The countermeasure is that the output of the current optical amplifier 110 is fixed, and when the excitation power of the pre-amplifier 110 is controlled, the thermal lens of the rear optical amplifier 120 is There is no change in the quality, so the beam propagation system does not change.

Fig. 8 is a graph showing an example of the relationship between the peak power of the fundamental wave and the average power after the wavelength conversion in the second harmonic generation. As shown in Fig. 4(c), the period during which the seed light is CW and the period between the pulse and the pulse in the pulse burst are relatively low compared to the peak of the pulse, so the wavelength conversion can be substantially ignored. After the output. Therefore, the peak power of the fundamental wave is varied, whereby the average power after the wavelength conversion can be controlled.

Fig. 9 is a view showing a configuration of an example of the wavelength converter 130. The light beam lambda1 after the rear optical amplifier is condensed by the lens 131 and incident on the first wavelength conversion element 132. The wavelength conversion element 132 converts a part of the power of the light beam lambda1 into a light beam lambda2 of a different wavelength from the light beam lambda1. The light beam lambda1 and the light beam lambda2 are re-concentrated by the lens 133 and incident on the second wavelength conversion element 134. The wavelength conversion element 134 converts a part of the power of the light beam lambda1 and the light beam lambda2 into a light beam lambda3 having a wavelength different from that of the light beam lambda1 and the light beam lambda2. The light beams lambda1, lambda2, and lambda3 are incident on the wavelength selective element 135, and selectively only the light beam lambda3 is taken out. For example, the beam lambda1 has a wavelength of 1064 nm, the beam lambda2 has a wavelength of 532 nm, and the beam lambda3 has a wavelength of 355 nm. The wavelength conversion elements 131 and 134 are, for example, crystals of LBO, BBO, CLBO, CBO, KBBF, and KTP. The wavelength selecting element 135 is, for example, a mirror that reflects/transmits the wavelength of the light beam lambda3, and a mirror that transmits/reflects the wavelengths of the light beam lambda1 and the light beam lambda2, and a prism or the like. The composition of the present invention is not used, When the propagation of the light beam after the rear optical amplifier 120 changes, the beam diameters in the wavelength conversion elements 132 and 134 are changed. The change in the beam diameter in the wavelength conversion element affects the wavelength conversion efficiency and the lifetime of the wavelength conversion element. When the configuration of the present invention is used, the influence of these effects can be suppressed. Therefore, when the wavelength converter 130 is provided, the present invention achieves further effects.

Embodiment 2

Fig. 10 is a view showing the configuration of a laser device according to a second embodiment of the present invention. The laser device 100 includes a seed light source 1, a front optical amplifier 110, a rear optical amplifier 120, a wavelength converter 130, a control unit 2, a seed light source driver 3, a front optical amplifier driver 4, and a rear optical amplifier driver 9. And the power monitor unit PM and the like. Since the individual components are the same as those of the first embodiment, the description thereof will not be repeated.

In the present embodiment, even when the output state of the seed light source 1 is changed while the excitation light power of the front optical amplifier 110 is maintained constant, the gain of the post-amplifier 120 can be controlled to control the subsequent state. The intensity of the thermal lens of the optical amplifier 120 does not change. Specifically, the control unit 2 transmits the feed lens to the rear optical amplifier driver 9 in accordance with the measurement result of the power monitor unit PM so that the thermal lens of the rear optical amplifier 120 can be fixed. The gain of the post-amplifier 120 is controlled, preferably with feedforward control of the excitation optical power.

In Fig. 10, the control unit 2 measures the measurement result of the power monitor unit PM, and measures the thermal lens of the rear optical amplifier 120 in advance. The excitation light power of the optical amplifier 120 is fixed, and the relationship between the two is stored in a memory or the like as a database. At the time of the operation, the output state of the seed light source 1 changes, and the average power of the output of the front optical amplifier 110 changes, and this state is measured by the power monitor unit PM. The control unit 2 reads the excitation light power target value corresponding to the changed average power from the data library so as not to change the thermal lens of the rear optical amplifier 120, and adjusts it through the rear optical amplifier driver 9. The excitation light power of the post-amplifier 120. As a result, the excitation light power of the front optical amplifier 110 can be made constant, the propagation of the light beam after the rear optical amplifier 120 is not changed, and the peak power or pulse energy of the pulse light is controlled to a wide range.

Embodiment 3

In the present embodiment, in the configuration of Fig. 1, the excitation light of the front optical amplifier 110 is substantially not changed by controlling the gain of the front optical amplifier 110, and the excitation light of the front optical amplifier 110 is not substantially changed. The wavelength changes. When the wavelength of the excitation light changes, the excitation light absorption rate of the fiber-type amplification medium 113 in the front optical amplifier 110 is changed, and the gain of the front optical amplifier 110 is changed. According to this, in the same manner as in the first embodiment, the average power after the front optical amplifier 110 can be controlled.

In the configuration of Fig. 2, a wavelength-variable semiconductor laser can be used for the semiconductor laser 111 for supplying excitation light to the fiber-type amplification medium 113. In one example, a Peltier element is used to control the temperature of a Fabry-Berro type semiconductor laser, thereby generating an oscillation wavelength. Variety.

The control unit 2 changes the wavelength of the excitation light of the semiconductor laser 111 by the pre-optical amplifier driver 4 based on the measurement result of the power monitor unit PM, and feedbacks the gain of the pre-optical amplifier 110. The average power after the front optical amplifier 110 can be kept constant.

Fig. 11 is a graph showing the absorption spectrum of Yb. The vertical axis is the absorption coefficient and the horizontal axis is the wavelength. For example, when Yb is added to the fiber-type amplification medium 113 of the pre-amplifier 110, the wavelength of the excitation light is changed by a few nm from the peak of the absorption spectrum at 976 nm, and the absorption coefficient is largely changed. In this case, since the power of the excitation light absorbed by the optical fiber type amplifying medium 113 is changed, the gain of the front optical amplifier 110 is also changed, and the average power after the front optical amplifier 110 is changed.

Embodiment 4

In the present embodiment, in the configuration of Fig. 10, by controlling the gain of the rear optical amplifier 120, the excitation light power of the rear optical amplifier 120 is substantially not changed, and the excitation light of the rear optical amplifier 120 is made. The wavelength changes. When the wavelength of the excitation light changes, the excitation light absorption rate of the amplification medium 122 in the post-optical amplifier 120 is changed, and the gain of the post-optical amplifier 120 is changed. According to this, in the same manner as in the second embodiment, it is possible to control so that the intensity of the thermal lens of the rear optical amplifier 120 does not change.

In the configuration of FIG. 3, it is used to amplify the medium 122. For the excitation light sources 123a, 123b that supply the excitation light, a wavelength-variable semiconductor laser can be used. As an example, the temperature of the Fabry-Berro type semiconductor laser is controlled using a Peltier element, whereby the oscillation wavelength can be changed.

The control unit 2 changes the wavelength of the excitation light of the excitation light sources 123a and 123b through the post-optical amplifier driver 9 based on the measurement result of the power monitor unit PM, and feeds forward the gain of the post-amplifier 120. The characteristics of the thermal lens of the post-amplifier 120 can be kept constant.

Embodiment 5

Fig. 12 is a view showing the configuration of a laser device according to a fifth embodiment of the present invention. The laser device 100 includes a seed light source 1, a front optical amplifier 110, a rear optical amplifier 120, a wavelength converter 130, a control unit 2, a seed light source driver 3, a front optical amplifier driver 4, and a rear optical amplifier driver 9. The beam monitor unit BM that monitors the profile of the beam after the post-amplifier, and the beam monitor 11 that monitors the contour of the beam extracted by the beam extracting means 10 and the like. Since the individual components are the same as those of the first embodiment, the description thereof will not be repeated.

In the present embodiment, the beam monitor unit BM is composed of a beam extracting means 10 for extracting one of the beams after the post-amplifier, and a beam monitor 11 for measuring the contour of the incident beam, and monitoring the post-amplifier 120. The contour of the back beam and the diameter of the beam is calculated. The beam extraction means 10 is, for example, a partial reflection mirror that only reflects or transmits a portion of the beam. The beam monitor 11 is, for example, a CCD image sensor (image) Sensor), and CMOS image sensor. When the intensity of the thermal lens generated by the post-optical amplifier 120 changes, the profile of the beam monitored by the beam monitor 11 changes, and the calculated beam diameter also changes. Therefore, the change in the intensity of the thermal lens generated by the post-optical amplifier 120 can be observed based on the change in the beam diameter calculated by the beam monitor unit BM. The control unit 2 transmits the excitation power or the excitation wavelength of the pre-optical amplifier 110 to control the gain through the pre-optical amplifier driver 4, or transmits the post-amplifier driver 9, and adjusts the excitation power or excitation of the post-amplifier 120. The wavelength is used to control the gain so that the diameter of the beam calculated by the beam monitor portion BM does not change. As a result, it is not necessary to monitor the output of the front optical amplifier 110, and the intensity of the thermal lens generated by the rear optical amplifier 120 can be kept constant, and the propagation of the light beam after the rear optical amplifier 120 is not changed, that is, The peak power or pulse energy of the pulsed light is controlled over a wide range.

Embodiment 6

Figure 13 is a view showing the configuration of a laser processing machine according to a sixth embodiment of the present invention. The laser processing machine 200 includes a laser device 100, a beam adjustment optical system 201, a light guiding mirror 202, a collecting lens 203, a stage table 204, and the like. The laser device 100 is constituted by the method described in any one of the first to fifth embodiments of the present invention. The laser beam 205 emitted from the laser device 100 is adjusted and shaped into a desired beam diameter and contour by the beam adjusting optical system 201, and is guided by the light guiding mirror 202, and then concentrated by light. The lens 203 is condensed on the workpiece 206. The susceptor table 204 is moved in the direction of the susceptor scanning direction 207 to scan the position of the workpiece 206 with respect to the laser beam, thereby forming a finely machined hole 208 at a desired position. The type of the processing hole 208 is, for example, a blind hole or a through hole. The processing holes 208 can also be of different sizes. Further, in the present embodiment, the base unit 204 is scanned in the susceptor scanning direction 207. However, the present invention is not limited to this case, and the relative relationship between the workpiece 206 and the laser beam 205 can be performed. Scanning, the susceptor table 204 is fixed, and the same effect can be obtained by scanning the laser beam 205 by a current (galvano) mirror, a polygon mirror or the like. In this case, the F θ lens 203 can be used as the condensing lens 203 to perform irradiation. The workpiece 206 is, for example, a flexible substrate, a multilayer substrate, or the like. Since these substrates are composed of a resin and a copper foil, the wavelength of the laser beam 205 is preferably such that it has an ultraviolet region that is absorbed by both the resin and the copper foil.

By using the laser device described in any one of the first to fifth embodiments of the present invention, the laser device 100 controls the optimum pulse energy for forming the processing hole 208 for the workpiece 206 and In the state of the peak power, the beam can be irradiated onto the workpiece 206 without changing the propagation of the beam. Therefore, the diameter of the beam of the workpiece 206 can be changed without changing the beam diameter at the position of the workpiece 206.

The present invention has been described in connection with the preferred embodiments and the drawings. However, those skilled in the art of the present invention are aware of various changes and modifications. Such changes or modifications are to be understood by the scope of the appended claims, and should be understood without departing from the scope of the invention.

1‧‧‧ Seed light source

2‧‧‧Control Department

3‧‧‧Seed light source driver

4‧‧‧Front optical amplifier driver

5‧‧‧ Output extraction means

6, 8‧ ‧ light

7‧‧‧Power monitor circuit

9‧‧‧ Rear Optical Amplifier Driver

100‧‧‧ Laser device

110‧‧‧front optical amplifier

120‧‧‧ rear optical amplifier

130‧‧‧wavelength converter

PM‧‧‧Power Monitor Department

Claims (11)

A laser device comprising: a seed light source for outputting light; a front optical amplifier for optically amplifying light outputted from the seed light source; and a post optical amplifier from the front optical amplifier The output light is optically amplified and includes an amplifying medium having a thermal lens function; the power monitor unit measures the average power of the light output from the pre-amplifier; and the seed light source driver drives the seed light source; a front optical amplifier driver driving the front optical amplifier; and a control unit for controlling the seed light source driver and the front optical amplifier driver; wherein the control unit controls the seed light source through the seed light source driver to cause the seed light source to be controlled Selectively outputting continuous light or a plurality of pulses, and the control unit controls the gain of the front optical amplifier by the front optical amplifier driver based on the measurement result of the power monitor unit, and the front portion is controlled from the front The average power of the light output by the optical amplifier can be fixed. A laser device comprising: a seed light source, which is an output light; The front optical amplifier optically amplifies the light output from the seed light source; the rear optical amplifier optically amplifies the light output from the front optical amplifier, and includes the thermal lens function. a power amplification unit that measures an average power of light output from the front optical amplifier; a seed light source driver that drives the seed light source; and a rear optical amplifier driver that drives the rear optical amplifier; The control unit controls the seed light source driver and the post-optical amplifier driver; the control unit controls the seed light source through the seed light source driver to selectively output continuous light or a plurality of pulses, and the control unit The gain of the post-optical amplifier is controlled by the post-optical amplifier driver based on the measurement result of the power monitor unit, and the propagation state of the beam after the post-amplifier is fixed. A laser device comprising: a seed light source for outputting light; a front optical amplifier for optically amplifying light outputted from the seed light source; and a post optical amplifier from the front optical amplifier Output The light is optically amplified and includes an amplifying medium having a thermal lens function; the beam monitor portion is a beam diameter of the light beam measured from the light output from the rear optical amplifier; and the seed light source driver drives the seed light source a post-optical amplifier driver for driving the post-optical amplifier; and a control unit for controlling the seed light source driver and the post-optical amplifier driver; wherein the control unit controls the seed light source through the seed light source driver, Selectively outputting continuous light or a plurality of pulses, wherein the control unit controls the gain of the front optical amplifier through the front optical amplifier driver, or controls the rear optical amplifier through the rear optical amplifier driver. The gain, so that the beam diameter calculated according to the aforementioned beam monitor portion does not change. The laser device according to any one of claims 1 to 3, wherein the seed light source is a semiconductor laser. The laser device according to claim 1 or 3, wherein the front optical amplifier comprises an optical fiber type amplifying medium, and an excitation light source for supplying excitation light to the optical fiber type amplifying medium, wherein the control unit is used. To control the excitation of the aforementioned pre-amplifier At least one of optical power and excitation light wavelength. The laser device according to claim 1 or 3, wherein the rear optical amplifier comprises a columnar amplifying medium having a thermal lens function and an excitation light source for supplying excitation light to the columnar amplifying medium. The laser device of claim 2, wherein the rear optical amplifier comprises a columnar amplifying medium having a thermal lens function, and an excitation light source for supplying excitation light to the columnar amplifying medium. The control unit is configured to control at least one of excitation light power and excitation light wavelength of the post-amplifier. The laser device according to claim 2, wherein the front optical amplifier comprises a fiber-type amplifying medium and an excitation light source for supplying excitation light to the fiber-type amplifying medium. A laser device according to any one of claims 1 to 3, wherein the post-optical amplifier is followed by a wavelength converter. A laser processing machine comprising: the laser device according to any one of claims 1 to 3; the concentrating optical system is a light output from the laser device The laser beam is concentrated; and the scanning mechanism performs relative scanning of the concentrated laser beam and the processed object. The laser processing machine of claim 10, wherein the wavelength of the aforementioned laser beam is an ultraviolet region.