Patent Application
20230075209
The present disclosure relates to a laser processing apparatus and a laser processing method.
Patent Document 1 discloses a technique related to a laser processing method. In the method, a material removal rate is increased by combining at least two light pulses (bursts) each having a pulse width of 10 picoseconds to 100 picoseconds. For generating the two light pulses with a time difference, an optical path of laser light from a laser oscillator is branched by a beam splitter, the light is propagated through two optical paths having different optical path lengths, and then the optical paths are combined by a beam combiner.
Patent Document 2 discloses a technique related to a laser processing method and a laser processing apparatus. In the method and the apparatus, two types of light pulses having different pulse widths are applied to a processing object. For this purpose, in one example, a laser light source for outputting one light pulse and another laser light source for outputting the other light pulse are provided.
Patent Document 1: Japanese Patent Application Laid-Open Publication No. 2005-511314
Patent Document 2: Japanese Patent Application Laid-Open Publication No. 2013-128088
In recent years, a technique for performing laser processing using a light pulse having a time width on the order of nanoseconds or picoseconds has been studied. In such laser processing, various effects in the laser processing can be obtained by performing irradiation with a plurality of light pulses with a time difference.
For example, in Patent Document 1 described above, it is described that the material removal rate is increased by performing irradiation with the two light pulses with a time difference. In addition, by making the time waveform of the light pulse different between the plurality of light pulses, additional effects may be achieved. For example, in Patent Document 2 described above, it is described that damage to a non-processing region can be avoided by performing irradiation with the two light pulses having different time widths.
However, in the method described in Patent Document 1, since the time difference between the two light pulses is realized by an optical path difference between the two optical paths, an optical path difference corresponding to a desired time interval is required. For example, when the time difference is 5 nanoseconds, the optical path difference is about 1.5 m. Further, when the time difference is 5 microseconds, the optical path difference is about 1500 m. Therefore, there is a problem that the apparatus scale becomes too large. Further, since a large loss occurs while the laser light propagates through such a long optical path, there is also a problem that energy efficiency is low.
In the apparatus and the method described as the example in Patent Document 2, since the plurality of laser light sources respectively corresponding to the plurality of light pulses having different time widths are required, the number of laser light sources increases as the number of types of light pulses increases, which is a factor that hinders the size reduction and cost reduction of the laser processing apparatus.
An object of the present invention is to provide a laser processing apparatus and a laser processing method capable of reducing a size of a configuration in which a processing object is irradiated with a plurality of light pulses having different time waveforms.
An embodiment of the present invention is a laser processing apparatus. The laser processing apparatus includes a semiconductor laser element; a waveform output unit for outputting input waveform data; a driver circuit for generating a drive current having a time waveform according to the input waveform data and supplying the drive current to the semiconductor laser element; and an optical system for irradiating a processing object with laser light output from the semiconductor laser element, and the semiconductor laser element outputs the laser light in which two or more light pulse groups each including one or a plurality of light pulses are provided with a time interval therebetween, time waveforms of at least two light pulse groups out of the two or more light pulse groups are different from each other, and the time waveform includes at least one of a time waveform of each of the one or plurality of light pulses, a time width of each of the one or plurality of light pulses, and a time interval of the plurality of light pulses.
An embodiment of the present invention is a laser processing method. The laser processing method includes a current supply step of generating a drive current having a time waveform according to input waveform data and supplying the drive current to a semiconductor laser element; and a light irradiation step of irradiating a processing object with laser light output from the semiconductor laser element, and in the light irradiation step, the semiconductor laser element outputs the laser light in which two or more light pulse groups each including one or a plurality of light pulses are provided with a time interval therebetween, time waveforms of at least two light pulse groups out of the two or more light pulse groups are different from each other, and the time waveform includes at least one of a time waveform of each of the one or plurality of light pulses, a time width of each of the one or plurality of light pulses, and a time interval of the plurality of light pulses.
In the above laser processing apparatus and the laser processing method, the waveform output unit outputs the input waveform data, and the driver circuit supplies the drive current having the time waveform according to the input waveform data to the semiconductor laser element. Therefore, by including an arbitrary time waveform in the input waveform data, a light pulse having an arbitrary time waveform can be output from the semiconductor laser element. Further, by including a plurality of pulse groups having a time difference in the input waveform data, a plurality of light pulse groups having a time difference can be output from the semiconductor laser element.
That is, according to the above apparatus and the method, it is possible to irradiate the processing object with the plurality of light pulse groups having different time waveforms with the time difference therebetween. In addition, since the plurality of light pulse groups are output from the single semiconductor laser element on a single optical path, the apparatus configuration can be reduced in size as compared with the methods described in Patent Documents 1 and 2.
According to the embodiments of the present invention, it is possible to provide a laser processing apparatus and a laser processing method capable of reducing a size of a configuration in which a processing object is irradiated with a plurality of light pulses having different time waveforms.
Hereinafter, embodiments of a laser processing apparatus and a laser processing method will be described in detail with reference to the accompanying drawings. In the description of the drawings, the same elements will be denoted by the same reference signs, and redundant description will be omitted. Further, the present invention is not limited to these examples.
An input end of the driver circuit 4 is electrically connected to the waveform output unit 6, and receives the input waveform data Da from the waveform output unit 6. The driver circuit 4 generates a drive current id having a time waveform according to the input waveform data Da. An output end of the driver circuit 4 is electrically connected to the semiconductor laser element 2, and supplies the generated drive current id to the semiconductor laser element 2. In addition, a bias current having a constant magnitude without time change may be superimposed on the drive current id.
The semiconductor laser element 2 is a laser diode, and is electrically connected to the driver circuit 4. The driver circuit 4 supplies the drive current id to any one of a cathode and an anode of the semiconductor laser element 2. The semiconductor laser element 2 receives the drive current id and generates laser light La. The laser light La is light before amplification by the optical amplifier 3, and has a time waveform according to the input waveform data Da.
In one example, the semiconductor laser element 2 is a distributed feedback (DFB) laser diode. When the semiconductor laser element 2 is a DFB laser diode, optimization according to a wavelength property of a gain of the optical amplifier 3 can be easily performed. An output power of the semiconductor laser element 2 is, for example, several nanojoules.
A light input end of the optical amplifier 3 is optically coupled to the semiconductor laser element 2, and amplifies the laser light La output from the semiconductor laser element 2. The optical amplifier 3 does not convert the laser light La into an electric signal, and directly amplifies the light as it is. The optical amplifier 3 may be constituted by, for example, an optical fiber amplifier, a solid-state laser amplifier, or a combination thereof.
The optical fiber amplifier includes an optical fiber made of glass with added impurities such as Er or Yb, and amplifies the laser light La by inputting excitation light to the optical fiber together with or prior to the laser light La. Further, the solid-state laser amplifier may include glass, yttrium aluminum garnet (YAG), or neodymium yttrium orthovanadate (YVO4) with added impurities such as Nd. The solid-state laser amplifier amplifies the laser light La by inputting excitation light together with or prior to the laser light La. The gain of the optical amplifier 3 is, for example, within a range of 3 dB to 30 dB.
The processing optical system 5 includes an optical path extending from an output end of the optical amplifier 3 and a focusing optical system provided on the optical path. The laser light Lb after the amplification output from the optical amplifier 3 propagates through the optical path of the processing optical system 5 to reach the focusing optical system, and is focused by the focusing optical system and applied to a processing object B.
The computer 31 includes a CPU and a memory, and operates according to a program stored in the memory. The memory of the computer 31 is a storage unit in the present embodiment, and stores data representing a desired (arbitrary) time waveform, that is, a target waveform (hereinafter referred to as target waveform data) in advance.
The target waveform data is stored in the memory in advance by an operator through a data input terminal of the computer 31 before the operation of the laser processing apparatus 1A. Further, the computer 31 may design the target waveform by itself as a waveform design unit. That is, the computer 31 may calculate a target waveform for achieving light irradiation conditions (processing conditions, observation conditions) given from the outside. The target waveform data representing the calculated target waveform is stored in the memory of the computer 31.
The comparison unit 33 is electrically connected to a photodetection unit 14 to be described later, and acquires a time waveform of the laser light Lb based on a detection signal (light intensity signal Sc) obtained from the photodetection unit 14. Further, the comparison unit 33 is electrically connected to the computer 31, and acquires the target waveform data Db from the computer 31. The comparison unit 33 compares the time waveform of the laser light Lb with the target waveform, and sends difference data Dc representing the difference to the waveform adjustment unit 32.
In addition, the comparison unit 33 may be constituted by a computer including a CPU and a memory. In this case, the comparison unit 33 may be provided separately from the computer 31, or may be implemented in a computer in common with the computer 31.
The waveform adjustment unit 32 is electrically connected to the computer 31, and acquires the target waveform data Db from the computer 31. Further, the waveform adjustment unit 32 is electrically connected to the comparison unit 33, and acquires the difference data Dc output from the comparison unit 33. The waveform adjustment unit 32 generates the input waveform data Da so that the time waveform of the laser light Lb approaches the target waveform (that is, the difference becomes small) based on the data Db and Dc.
In addition, the waveform adjustment unit 32 may also be constituted by a computer including a CPU and a memory. In this case, the waveform adjustment unit 32 may be provided separately from the computer 31 and the comparison unit 33, or may be implemented in a computer in common with at least one of the computer 31 and the comparison unit 33.
The laser processing apparatus 1A illustrated in
The optical branch unit 13 and the photodetection unit 14 constitute a light waveform detection unit 15. The light waveform detection unit 15 detects the time waveform of the laser light Lb after the amplification output from the optical amplifier 3. The optical branch unit 13 is optically coupled to a light output end of the optical amplifier 3. The optical branch unit 13 branches a part Lb1 of the laser light Lb after the amplification from the laser light Lb by reflecting (or transmitting) the part Lb1 of the laser light Lb after the amplification output from the optical amplifier 3. The optical branch unit 13 may be constituted by, for example, a glass plate.
A ratio (branching ratio) P1/P2 of an intensity P1 of the part Lb1 of the laser light Lb and an intensity P2 of the remaining part is, for example, within a range of 0.005 to 0.01. The photodetection unit 14 is optically coupled to the optical branch unit 13, and receives the part Lb1 of the laser light Lb after the amplification. In addition, the remaining part of the laser light Lb is applied to the processing object B through the processing optical system 5 illustrated in
The photodetection unit 14 generates the light intensity signal Sc being an electric signal according to the light intensity of the part Lb1 of the laser light Lb, and provides the light intensity signal Sc to the comparison unit 33. In one example, the photodetection unit 14 may be constituted by including a photodiode and a circuit for converting a photocurrent flowing through the photodiode into a voltage signal.
The photodetection unit 14 may output the generated voltage signal as the light intensity signal Sc, or may convert the generated voltage signal into a digital signal and output the digital signal as the light intensity signal Sc. When the light intensity signal Sc is the voltage signal, it is converted into the digital signal in the comparison unit 33. In addition, the photodetection unit 14 may include a phototube (for example, a biplanar phototube) instead of the photodiode.
A light input end of the optical fiber amplifier 22 and the semiconductor laser element 2 are optically coupled via an optical fiber F1. The optical isolator 21 is interposed between the optical fiber amplifier 22 and the semiconductor laser element 2. The optical isolator 21 prevents the light (laser light La and excitation light) from returning from the optical fiber amplifier 22 to the semiconductor laser element 2. Thus, damage to the semiconductor laser element 2 can be prevented.
A light output end of the optical fiber amplifier 22 and the bandpass filter 24 are optically coupled via an optical fiber F2. The optical isolator 23 is interposed between the optical fiber amplifier 22 and the bandpass filter 24. The optical isolator 23 prevents the light at a stage after the bandpass filter 24 from returning to the optical fiber amplifier 22.
The optical fiber amplifier 22 is a first stage optical amplifier, and amplifies the laser light La output from the semiconductor laser element 2. The gain of the optical fiber amplifier 22 is, for example, within a range of 20 dB to 30 dB. The optical fiber amplifier 22 is, for example, an ytterbium-doped fiber (YDF). The bandpass filter 24 blocks a wavelength component of fluorescence contained in the light output from the optical fiber amplifier 22. The bandpass filter 24 may be constituted by, for example, a dielectric multilayer film.
The bandpass filter 24 is optically coupled to the optical fiber connector 25 via an optical fiber F3. The optical fiber connector 25 terminates the optical fiber F3. That is, the light passing through the bandpass filter 24 propagates through the optical fiber F3, reaches the optical fiber connector 25, and then is output to a space.
The collimator lens 26 is optically coupled to the optical fiber connector 25 via the space, and parallelizes (collimates) the light radially output from the optical fiber connector 25. Since an intensity of light amplified by the solid-state laser amplifiers 28 and 30 to be described later is high, in order to avoid damage by the laser to an optical material such as glass, the light is propagated in the space instead of in an optical fiber at a stage after the optical fiber connector 25. In addition, in
The solid-state laser amplifier 28 is optically coupled to the collimator lens 26 via the optical isolator 27. The optical isolator 27 prevents the light of the solid-state laser amplifier 28 from returning to a stage before the solid-state laser amplifier 28. Thus, damage to the optical fiber amplifier 22 can be prevented.
The solid-state laser amplifier 28 is a second stage optical amplifier, and further amplifies the laser light after the amplification output from the optical fiber amplifier 22. The gain of the solid-state laser amplifier 28 is, for example, within a range of 3 dB to 20 dB.
The solid-state laser amplifier 30 is optically coupled to the solid-state laser amplifier 28 via the optical isolator 29. That is, the optical fiber amplifier 22 and the solid-state laser amplifiers 28 and 30 are coupled in series with each other. The optical isolator 29 prevents the light of the solid-state laser amplifier 30 from returning to a stage before the solid-state laser amplifier 30. Thus, damage to the solid-state laser amplifier 28 can be prevented.
The solid-state laser amplifier 30 is a third stage optical amplifier, and further amplifies the laser light after the amplification output from the solid-state laser amplifier 28. The gain of the solid-state laser amplifier 30 is, for example, within a range of 3 dB to 10 dB. The light amplified by the solid-state laser amplifier 30 is output as the laser light Lb after the amplification.
The control board 41 is a circuit board serving as an interface with the waveform output unit 6. The CPU 41a is electrically connected to the waveform adjustment unit 32 (see
The waveform adjustment unit 32 of the present embodiment outputs the input waveform data Da as a plurality of continuous section waveform data obtained by dividing the time waveform of the input waveform data Da (details will be described later). These section waveform data are output in parallel and simultaneously for every two or more section waveform data. Then, the waveform data storage unit 42 stores the plurality of section waveform data, and outputs the plurality of section waveform data according to a request.
The waveform timing adjustment unit 43 is electrically connected to the waveform data storage unit 42, and adjusts (controls) a timing at which the input waveform data Da is output from the waveform data storage unit 42.
The waveform signal generation unit 44 sequentially inputs the plurality of section waveform data DD1 to DD4 output from the waveform timing adjustment unit 43, and sequentially converts the section waveform data DD1 to DD4 into the drive signal Sd being an analog signal (voltage signal). In this case, a time difference between conversion timings of the section waveform data DD1 to DD4 substantially coincides with the time difference given by the waveform timing adjustment unit 43.
In addition, the current conversion unit 45 is further connected to a bias current control unit 11. The bias current control unit 11 controls a magnitude of a bias component contained in the drive current id. The semiconductor laser element 2 is electrically connected to a current output end of the current conversion unit 45, receives the drive current id from the current conversion unit 45, and outputs the laser light La. The time waveform of the laser light La is substantially the same as the time waveform of the drive current id.
First, the waveform adjustment unit 32 sets initial input waveform data Da (step ST1). The initial input waveform data Da is set based on the target waveform data Db. In one example, the target waveform data Db is used as it is as the initial input waveform data Da. Next, the driver circuit 4 supplies the drive current id to the semiconductor laser element 2 based on the initial input waveform data Da, and the semiconductor laser element 2 outputs the laser light La (current supply step ST2). (a) in
In addition, the current supply step ST2 includes a D/A conversion step ST21 and a current conversion step ST22. In the D/A conversion step ST21, the D/A conversion unit 46 converts the digital input waveform data Da into the analog drive signal Sd. In this case, as described above, the plurality of continuous section waveform data DD1 to DD4 (see
Subsequently, the time waveform of the laser light Lb after the amplification is detected by the photodetection unit 14 (light waveform detection step ST4). (b) in
The driver circuit 4 supplies the drive current id to the semiconductor laser element 2 based on the new input waveform data Da, and the semiconductor laser element 2 outputs the laser light La (current supply step ST2). (d) in
A preferred time waveform of the laser light Lb will be further discussed.
In addition, a wavelength of the laser light Lb was set to 1064 nm, a repetition frequency of the light pulse Pa was set to 300 Hz, and the irradiation was performed for 3 seconds (that is, the number of times of irradiation of the light pulse Pa was 900), a pulse energy of the light pulse Pa was set to 40 μJ, and a plano-convex lens with a focal length of 40 mm was used as the focusing lens of the processing optical system 5. Further, the processing object B was set to 50 μm thick stainless steel (SUS304), and a focusing diameter of the laser light Lb on the processing object B was set to 10 μm.
(a) in
In addition, a pulse width of each ultrashort light pulse Pba included in the light pulse group Pb was set to 70 ps (FWHM), a time interval between the pulses was set to 2 ns, and the number of the ultrashort light pulses Pba was set to 10. Further, a repetition frequency of the light pulse group Pb was set to 300 Hz, and the irradiation was performed for 3 seconds (that is, the number of times of irradiation of the light pulse group Pb was 900), and a pulse energy of each ultrashort light pulse Pba was set to 40 μJ. The wavelength of the laser light Lb, the focusing lens of the processing optical system 5, the material of the processing object B, and the focusing diameter of the laser light Lb were the same as described above.
(a) in
The peak output of the Gaussian pulse Pa shown in
(a) in
In addition, the light pulse group Pc includes a plurality of ultrashort light pulses Pca, and is the same as the light pulse group Pb shown in
(b) in
The above depressed portion having the diameter much smaller than the focusing diameter of the laser light Lb is considered to be obtained as a result of processing by the light pulse group Pc including the plurality of ultrashort light pulses Pca having the time width of a picosecond order and processing by the light pulse Pd having the time width of a nanosecond order being performed in a combined manner. More specifically, it is estimated that hole processing is progressed by the light pulse group Pc having a high peak output, and thermal processing is progressed by energy irradiation for a long time through the light pulse Pd having a low peak output, and as a result, the processing object B (SUS304) is moderately melted, and the depressed portion with the small diameter is formed.
The example shown in
In addition, the time waveform used here is a concept including at least one of a time waveform of each of the one or plurality of pulses in each pulse group, a time width of each of the one or plurality of pulses in each pulse group, and a time interval of the plurality of pulses in each pulse group. The time interval Δt is, for example, 200 microseconds or less, and more preferably 1 microsecond or less.
According to the laser processing apparatus 1A of the present embodiment, as described above, it is possible to set the pulse width of the light pulse Peb included in one light pulse group Pe2 to 10 times or more of the pulse width of the light pulse Pea included in another light pulse group Pe1. In this case, the drive current id in which a pulse group corresponding to the light pulse group Pe1 and a pulse group corresponding to the light pulse group Pe2 are provided with the time interval Δt therebetween may be provided from the driver circuit 4 to the semiconductor laser element 2 in the current supply step ST2.
Further, (b) in
Further,
In addition, in each waveform shown in
(a) to (c) in
In addition, the number of the ultrashort light pulses included in the light pulse group Pi is arbitrary, and in the illustrated examples, the number of the ultrashort light pulses is 3. Further, peak intensities of the ultrashort light pulses included in the light pulse group Pi may be equal to each other, or at least one may be different from the others. Further, as in (a) and (b) in
(c) in
(a) in
(b) in
(c) in
(a) in
(b) in
(c) in
(a) in
(b) in
(c) in
(a) in
(b) in
(c) in
A pulse width (FWHM) of each ultrashort light pulse included in the light pulse group Pi is, for example, 1 picosecond or more and 1 nanosecond or less. A pulse width (FWHM) of the Gaussian pulse included in the light pulse group Pj is, for example, 1 nanosecond or more and 1 microsecond or less. A time width of the flat section of the light pulse included in the light pulse group Py is, for example, 1 microsecond or more and 1 millisecond or less. The time intervals Δt3 and Δt4 are, for example, 1 millisecond or less, and more preferably 200 microseconds or less.
In this example, first, a processing object surface is cleaned by irradiating the uppermost layer B1 with the light pulse group Py shown in (b) in
Subsequently, by irradiating the layer B2 with the light pulse group Pp shown in (b) in
In this way, it is possible to form a through hole in a short time in the processing object B constituted by laminating different types of materials.
In addition, a combination of a plurality of light pulse groups corresponding to a plurality of processing processes may be as the following configuration. (a) in
In addition, an example in which the processing object B is irradiated with a plurality of light pulse groups corresponding to a plurality of processing processes will be described.
The number of the light pulse groups Pi was set to 300, the number of the plurality of light pulses included in the light pulse group Pi was set to 10, an energy of each light pulse was set to 2 μJ, a time width (FWDM) of each light pulse was set to 80 ps, and a time interval between the pulses was set to 2 ns. Further, the number of the light pulse groups Pj was set to 300, an energy of the Gaussian pulse of the light pulse group Pj was set to 40 μJ, and a time width (FWDM) of the Gaussian pulse was set to 137 ns. Further, a time interval Δt5 between the light pulse groups Pi and the light pulse groups Pj was set to 1 s as a time with which the processing object B becomes a steady state after the processing of the light pulse groups Pi, a time interval between the light pulse groups Pi was set to 3.3 ms, and a time interval between the light pulse groups Pj was set to 3.3 ms.
When (a) in
In addition, when the hole diameter on the back surface of the processing object B was measured, the width dx in the horizontal direction of the paper plane was 8.3 μm, the width dy in the vertical direction of the paper plane was 8.1 μm, and the average width was 8.2 μm before the irradiation of the light pulse groups Pj ((b) in
Effects obtained by the laser processing apparatus 1A and the laser processing method of the present embodiment described above will be described.
In the laser processing apparatus 1A and the laser processing method of the present embodiment, the waveform output unit 6 outputs the input waveform data Da, and the driver circuit 4 supplies the drive current id having the time waveform according to the input waveform data Da to the semiconductor laser element 2. Therefore, by including an arbitrary time waveform in the input waveform data Da, a light pulse having an arbitrary time waveform can be output from the semiconductor laser element 2. Further, by including a plurality of pulse groups having a time difference in the input waveform data Da, a plurality of light pulse groups having a time difference can be output from the semiconductor laser element 2.
That is, according to the present embodiment, it is possible to irradiate the processing object B with the plurality of light pulse groups having different time waveforms with the time difference therebetween. In addition, since the plurality of light pulse groups are output from the single semiconductor laser element 2 on the single optical path, the apparatus configuration can be reduced in size as compared with the methods described in Patent Documents 1 and 2.
Further, by irradiating the processing object B with the plurality of light pulse groups having different time waveforms in a short period of time (continuously), the plurality of light pulse groups act on the processing object B in a combined manner, and various processing shapes and processing qualities, which have been considered difficult conventionally, such as formation of the depressed portion having the diameter smaller than the irradiation diameter as illustrated in (b) in
Further, as in the conventional technique, when a light source having an appropriate time waveform is prepared for each processing process and each processing process is performed, an operation for replacing the light source is necessary, and an operation for correcting a deviation of an optical axis after replacing the light source is further necessary, and thus, a time required for processing processes becomes long. On the other hand, according to the present embodiment, for example, as illustrated in
As in the present embodiment, the driver circuit 4 (current supply step ST2) may include the D/A conversion unit 46 (D/A conversion step ST21) for converting the digital input waveform data Da into the analog drive signal Sd, and the current conversion unit 45 (current conversion step ST22) for converting the drive signal Sd into the drive current id. Further, the D/A conversion unit 46 (D/A conversion step ST21) may sequentially convert the plurality of continuous section waveform data DD1 to DD4 obtained by dividing the time waveform of the input waveform data Da into the drive signal Sd while providing the time difference. In this case, it is possible to further increase a speed of the drive signal Sd and improve a time resolution of the time waveform of the light pulse.
As in the present embodiment, the time width of each of the one or plurality of pulses in each light pulse group may be 1 microsecond or less. By irradiating the processing object B with the light pulse having the short time width as described above, it is possible to increase a light intensity of the laser light Lb while controlling thermal influence on the periphery of the processing region, and it is possible to improve processing accuracy.
As in the present embodiment, the time interval between the light pulse groups may be 200 microseconds or less. In this case, it is possible to irradiate the processing object B with the laser light Lb including the two or more light pulse groups in a short time, and a time required for processing can be reduced.
As in the present embodiment, the waveform output unit 6 (in the current supply step ST2) may change the time waveform of at least one pulse group out of the two or more light pulse groups in the laser light Lb during processing of the processing object B. In the present embodiment, as described above, it is possible to easily change the time waveform of the pulse group during processing of the processing object B. Therefore, it is possible to continuously perform processing processes of a plurality of stages in which time waveforms required for the laser light are different from each other in a short time, and a time required for processing can be reduced.
As in the present embodiment, the pulse width of the one or plurality of light pulses in one light pulse group may be 10 times or more of the pulse width of the one or plurality of light pulses in another light pulse group. According to the present embodiment, for example, it is possible to continuously output the light pulses having greatly different pulse widths in a short time, and to adapt to various processing conditions.
(Modification)
The spatial light modulator 7 includes a plurality of pixels arranged two-dimensionally, and individually modulates a phase of incident light in each pixel. The spatial light modulator 7 may be a transmission type or a reflection type. In one example, the spatial light modulator 7 is a liquid crystal on silicon—spatial light modulator (LCOS-SLM) of a liquid crystal type.
The spatial light modulator 7 is disposed on an optical path between the semiconductor laser element 2 and the processing optical system 5 (in the illustrated example, on an optical path between the optical amplifier 3 and the processing optical system 5). The spatial light modulator 7 spatially modulates the phase of the laser light Lb output from the optical amplifier 3, and outputs the laser light Lc after the modulation to the processing optical system 5. The laser light Lc is applied to the processing object B via the processing optical system 5. That is, in the light irradiation step ST6 illustrated in
The drive unit 8 is a circuit for applying a voltage signal Sv for driving the spatial light modulator 7 to each pixel of the spatial light modulator 7. The magnitude of the voltage signal Sv for each pixel is determined based on a computer generated hologram (CGH) generated in the waveform output unit 6.
In addition, in the present modification, the spatial light modulator 7 presents a CGH for making positions on the processing object B to which the light pulse groups Py1, Py2, Py3 are applied different for the respective light pulse groups Py1, Py2, Py3, or making an irradiation position of at least one light pulse group Py1, Py2, or Py3 different from an irradiation position of the other light pulse groups. In other words, the spatial light modulator 7 sequentially presents the CGH for irradiating the first irradiation position with the first light pulse group Py1 (or Py2) and the CGH for irradiating the second irradiation position different from the first irradiation position with the second light pulse group Py2 (or Py3). In addition, the times Δt6 and Δt7 described above are longer than a time required for the spatial light modulator 7 to change the CGH.
According to the present modification, at least two processing portions can be irradiated with the light pulse groups having different time waveforms, and the irradiation of these light pulse groups can be continuously performed in a short time. Therefore, a time required for processing can be remarkably reduced as compared with the conventional laser processing apparatus.
The laser processing apparatus and the laser processing method are not limited to the embodiments and configuration examples described above, and may be modified in various ways. For example, the target waveform data is stored in the waveform output unit 6 in the above embodiment, and further, the target waveform data may be input from the outside of the laser processing apparatus 1A. Further, the optical amplifier 3 and/or the optical isolator 12 may be omitted as appropriate.
Further, in the above embodiment, the waveform output unit 6 includes the waveform adjustment unit 32 and the comparison unit 33, and generates the input waveform data Da by performing feedback of the time waveform of the laser light Lb, and further, the configuration for the feedback may not be provided, and the target waveform data Db from the computer 31 may be used as it is to generate the laser light Lb.
The laser processing apparatus of the above embodiment includes a semiconductor laser element; a waveform output unit for outputting input waveform data; a driver circuit for generating a drive current having a time waveform according to the input waveform data and supplying the drive current to the semiconductor laser element; and an optical system for irradiating a processing object with laser light output from the semiconductor laser element, and the semiconductor laser element outputs the laser light in which two or more light pulse groups each including one or a plurality of light pulses are provided with a time interval therebetween, time waveforms of at least two light pulse groups out of the two or more light pulse groups are different from each other, and the time waveform includes at least one of a time waveform of each of the one or plurality of light pulses, a time width of each of the one or plurality of light pulses, and a time interval of the plurality of light pulses.
The laser processing method of the above embodiment includes a current supply step of generating a drive current having a time waveform according to input waveform data and supplying the drive current to a semiconductor laser element; and a light irradiation step of irradiating a processing object with laser light output from the semiconductor laser element, and in the light irradiation step, the semiconductor laser element outputs the laser light in which two or more light pulse groups each including one or a plurality of light pulses are provided with a time interval therebetween, time waveforms of at least two light pulse groups out of the two or more light pulse groups are different from each other, and the time waveform includes at least one of a time waveform of each of the one or plurality of light pulses, a time width of each of the one or plurality of light pulses, and a time interval of the plurality of light pulses.
In the above laser processing apparatus, the driver circuit may include a D/A conversion unit for converting the digital input waveform data into an analog drive signal; and a current conversion unit for converting the drive signal into the drive current, and the D/A conversion unit may sequentially convert a plurality of continuous section waveform data obtained by dividing the time waveform of the input waveform data into the drive signal while providing a time difference.
In the above laser processing method, the current supply step may include a D/A conversion step of converting the digital input waveform data into an analog drive signal; and a current conversion step of converting the drive signal into the drive current, and in the D/A conversion step, a plurality of continuous section waveform data obtained by dividing the time waveform of the input waveform data may be sequentially converted into the drive signal while providing a time difference.
According to the above apparatus and the method, it is possible to further increase a speed of the drive signal and improve a time resolution of the time waveform of the light pulse.
In the above laser processing apparatus and the laser processing method, the time width of each of the one or plurality of light pulses in each light pulse group may be 1 microsecond or less. By irradiating the processing object with the light pulse having the short time width as described above, it is possible to increase a light intensity of the laser light while controlling thermal influence on the periphery of the processing region, and it is possible to improve processing accuracy.
In the above laser processing apparatus and the laser processing method, the time interval between the two or more light pulse groups may be 200 microseconds or less. In this case, it is possible to irradiate the processing object with the two or more light pulse groups in a short time, and a time required for processing can be reduced.
In the above laser processing apparatus, the waveform output unit may change the time waveform of at least one light pulse group out of the two or more light pulse groups during processing of the processing object. Further, in the above laser processing method, the time waveform of at least one light pulse group out of the two or more light pulse groups may be changed during processing of the processing object.
In the above apparatus and the method, as described above, it is possible to easily change the time waveform of the light pulse group during processing of the processing object. Therefore, it is possible to continuously perform processing of a plurality of stages in which time waveforms required for the laser light are different from each other in a short time, and a time required for processing can be reduced.
In the above laser processing apparatus and the laser processing method, a pulse width of the one or plurality of light pulses in one light pulse group out of the at least two light pulse groups may be 10 times or more of a pulse width of the one or plurality of light pulses in another light pulse group. According to the above apparatus and the method, for example, it is possible to continuously output the light pulses having greatly different pulse widths in a short time, and to adapt to various processing conditions.
The above laser processing apparatus may further include a spatial light modulator disposed on an optical path between the semiconductor laser element and the optical system, and the spatial light modulator may sequentially present a hologram for irradiating a first irradiation position with the laser light corresponding to a first light pulse group included in the two or more light pulse groups and a hologram for irradiating a second irradiation position different from the first irradiation position with the laser light corresponding to a second light pulse group.
In the above laser processing method, in the light irradiation step, the processing object may be irradiated with the laser light via a spatial light modulator, and a hologram for irradiating a first irradiation position with the laser light corresponding to a first light pulse group included in the two or more light pulse groups and a hologram for irradiating a second irradiation position different from the first irradiation position with the laser light corresponding to a second light pulse group may be sequentially presented on the spatial light modulator.
In this case, a plurality of processing portions can be continuously irradiated with the laser light in a short time, and a time required for processing can be reduced.
The present invention can be used as a laser processing apparatus and a laser processing method capable of reducing a size of a configuration in which a processing object is irradiated with a plurality of light pulses having different time waveforms.
1A, 1B—laser processing apparatus, 2—semiconductor laser element, 3—optical amplifier, 4—driver circuit, 5—processing optical system, 6—waveform output unit, 7—spatial light modulator, 8—drive unit, 11—bias current control unit, 12, 21, 23, 27, 29—optical isolator, 13—optical branch unit, 14—photodetection unit, 15—light waveform detection unit, 22—optical fiber amplifier, 24—bandpass filter, 25—optical fiber connector, 26—collimator lens, 28, 30—solid-state laser amplifier, 31—computer, 32—waveform adjustment unit, 33—comparison unit, 41—control board, 41a—CPU, 41b—high-speed DAC interface, 42—waveform data storage unit, 43—waveform timing adjustment unit, 44—waveform signal generation unit, 45—current conversion unit, 46—D/A conversion unit, B—processing object, B1—B3—layer, B1a, B2b, B3a—hole, B2a—modified region, Da—input waveform data, Db—target waveform data, Dc—difference data, DD1—DD4—section waveform data, F1-F3—optical fiber, id—drive current, La, Lb, Lc—laser light, Pa—light pulse (Gaussian pulse), Pb, Pc, Pe1, Pe2, Pf1, Pf2, Pg1, Pg2, Pg3, Ph1, Ph2, Pi—Pz, Py1, Py2, Py3—light pulse group, Pba, Pca, Pfa, Pga—ultrashort light pulse, Pd, Pea, Peb, Pfb, Pgb, Pgc, Pha, Phb—light pulse, Sc—light intensity signal, Sd—drive signal, Sv—voltage signal, TA—delay time, Δt, Δt1, Δt2, Δt5—time interval.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2020-030762 | Feb 2020 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2021/005012 | 2/10/2021 | WO |
