Light source for laser processing and laser processing apparatus

Abstract

The light source for laser processing includes: a laser oscillation unit that emits a first pulse light train; a first light generation unit that generates a third pulse light train including a plurality of second pulse light trains by performing wavelength division, propagation on a plurality of optical paths, and wavelength combination on the first pulse light train; a second light generation unit that selects at least one second pulse light train from the plurality of second pulse light trains in the third pulse light train to generate a fourth pulse light train including at least one second pulse light train; and a control unit that controls the second light generation unit; the control unit sends a control signal for selecting at least one second pulse light train from the plurality of second pulse light trains in the third pulse light train to the second light generation unit.

Description

Technical Field

[0001] The present invention relates to a light source for laser processing and a laser processing apparatus. Background Art

[0002] As a laser processing apparatus that irradiates a workpiece with a double-pulse light train composed of a plurality of double-pulse lights, there is known an apparatus that divides one pulse light train composed of a plurality of single-pulse lights into two pulse light trains, allows each of the two divided pulse light trains to propagate through optical paths having different optical path lengths, and combines the two pulse light trains to generate a double-pulse light train (for example, refer to Patent Document 1). In addition, a single-pulse light refers to one pulse of light composed of one pulse, and a double-pulse light refers to one pulse of light composed of, for example, two pulses that are close in time up to several ps to 20 ns.

[0003] Prior Art Documents

[0004] Patent Documents

[0005] Patent Document 1: Japanese Patent Laid-Open No. 11-221684 Summary of the Invention

[0006] Problems to be Solved by the Invention

[0007] However, in the above-described laser processing apparatus, there is a case where the pulse light train irradiated onto the workpiece is limited to one type of pulse light train (for example, a double-pulse light train). In order to process the workpiece according to various uses, it is convenient if various pulse light trains can be selectively irradiated onto the workpiece.

[0008] Therefore, an object of the present invention is to provide a light source for laser processing and a laser processing apparatus that can selectively emit a plurality of types of pulse light trains.

[0009] Means for Solving the Problems

[0010] The light source for laser processing of the present invention includes: a laser oscillation unit that emits a first pulse light train; a first light generation unit that generates a third pulse light train including a plurality of second pulse light trains by performing splitting, propagation on a plurality of optical paths, and combination on the first pulse light train; a second light generation unit that selects at least one second pulse light train from the plurality of second pulse light trains in the third pulse light train to generate a fourth pulse light train including at least one second pulse light train; and a control unit that controls the second light generation unit, and the control unit sends a control signal for selecting at least one second pulse light train from the plurality of second pulse light trains in the third pulse light train to the second light generation unit.

[0011] In this light source for laser processing, a third pulse light train including a plurality of second pulse light trains is generated, and in the third pulse light train, at least one second pulse light train is selected from the plurality of second pulse light trains, thereby generating a fourth pulse light train including at least one second pulse light train. Therefore, according to this light source for laser processing, various pulse light trains can be selectively emitted.

[0012] In the light source for laser processing of the present invention, it is also possible that the laser oscillation unit transmits an electrical signal having a frequency corresponding to the first pulse light train to the control unit, and the control unit generates a control signal based on the electrical signal. According to this structure, the control of the second light generation unit that selects at least one second pulse light train from the plurality of second pulse light trains in the third pulse light train can be performed correctly and easily.

[0013] In the light source for laser processing of the present invention, it is also possible that the second light generation unit is a regenerative amplifier, which has: a light extraction unit that generates the fourth pulse light train; a gain medium that forms an optical resonator together with the light extraction unit with respect to the fourth pulse light train; and an excitation light source that irradiates the gain medium with excitation light. According to this structure, the generation and amplification of the fourth pulse light train can be effectively performed.

[0014] In the light source for laser processing of the present invention, it is also possible that the plurality of second pulse light trains are respectively a single-pulse light train and a double-pulse light train. According to this structure, in the third pulse light train, for example, by selecting a single-pulse light train or a double-pulse light train from the plurality of second pulse light trains, a fourth pulse light train including a single-pulse light train or a double-pulse light train can be generated.

[0015] In the light source for laser processing of the present invention, it is also possible that the first light generation unit has: a first wavelength division unit that divides the first pulse light train into two pulse light trains; a first optical path and a second optical path, whose optical path lengths are different from each other, and that propagate each of the two pulse light trains; and a first multiplexing unit that generates the third pulse light train by multiplexing the two pulse light trains; the first optical path has: a second wavelength division unit that divides one of the two pulse light trains divided by the first wavelength division unit into two sub-pulse light trains; a third optical path and a fourth optical path, whose optical path lengths are different from each other, and that propagate each of the two sub-pulse light trains; and a second multiplexing unit that multiplexes the two sub-pulse light trains; the first multiplexing unit generates the third pulse light train by multiplexing the other of the two pulse light trains divided by the first wavelength division unit and the pulse light train multiplexed by the second multiplexing unit. According to this structure, the generation of the third pulse light train can be easily performed.

[0016] In the light source for laser processing of the present invention, it is also possible that the first wavelength division unit, the first multiplexing unit, the second wavelength division unit, and the second multiplexing unit are respectively couplers, and the first light generation unit further has an optical fiber that connects the couplers adjacent to each other on the optical path. According to this structure, the generation of the third pulse light train can be performed more easily.

[0017] In the light source for laser processing of the present invention, the first light generation unit and the second light generation unit may also be arranged via the space through which the third pulsed light train propagates. According to this structure, the first light generation unit can be easily loaded and unloaded independently of the second light generation unit.

[0018] The laser processing apparatus of the present invention includes the above-described light source for laser processing, a support unit that supports the workpiece, and an irradiation unit that irradiates the workpiece with the pulsed light train emitted from the light source for laser processing.

[0019] According to this laser processing apparatus, a plurality of pulsed light trains can be selectively irradiated onto the workpiece. Thereby, the workpiece can be appropriately processed according to various uses.

[0020] Effects of the Invention

[0021] According to the present invention, a light source for laser processing and a laser processing apparatus that can selectively emit a plurality of pulsed light trains can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 is a configuration diagram of the laser processing apparatus according to the first embodiment.

[0023] Figure 2 is Figure 1 a configuration diagram of the light source for laser processing shown.

[0024] Figure 3 is Figure 2 a configuration diagram of the first light generation unit shown.

[0025] Figure 4 is a configuration diagram of the first light generation unit according to the second embodiment.

[0026] Figure 5 is a configuration diagram of the first light generation unit according to a modification.

[0027] Figure 6 is a configuration diagram of the first light generation unit according to a modification. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, the same or corresponding parts are denoted by the same reference numerals in the respective drawings, and repeated descriptions are omitted.

[0029] [First Embodiment]

[0030] As Figure 1As shown in the figure, the laser processing apparatus 1 includes a light source 2 for laser processing, an irradiation optical system (irradiation unit) 3, a support unit 4, and a processing position control unit 5. The laser processing apparatus 1 is a device that generates plasma on the surface of a workpiece P such as metal by irradiating the surface of the workpiece P with pulsed laser light, i.e., a pulsed light train. The laser processing apparatus 1 plastically changes the surface of the workpiece P to a specified processing depth by means of a shock wave generated by plasma pressure.

[0031] The light source 2 for laser processing emits a pulsed light train. The irradiation optical system 3 irradiates the pulsed light train emitted from the light source 2 for laser processing onto the workpiece P. The irradiation optical system 3 includes a shutter that switches between irradiation and non-irradiation of the pulsed light train, a lens that condenses the pulsed light train at a measurement position, and mirrors, etc.

[0032] The support unit 4 supports the workpiece P. The processing position control unit 5 controls the irradiation position of the pulsed light train with respect to the workpiece P. The processing position control unit 5 aligns the irradiation position of the pulsed light train with the processing position of the workpiece P by moving at least one of the irradiation optical system 3 and the support unit 4.

[0033] As Figure 2 shown in the figure, the light source 2 for laser processing includes a laser oscillation unit 21, a first light generation unit 22, a second light generation unit 23, a control unit 24, and a user interface 25. The laser oscillation unit 21 is, for example, a mode-locked fiber laser oscillator. The laser oscillation unit 21 outputs an electrical signal E based on a pulsed light train (first pulsed light train) L1. A pulsed light train refers to laser light that includes a plurality of pulsed lights arranged at a specified time interval (pulse interval). The laser oscillation unit 21 sends the electrical signal E to the control unit 24. The electrical signal E has a frequency corresponding to the pulsed light train L1. As an example, the frequency of the electrical signal E is the same as the frequency of the pulsed light train L1.

[0034] The first light generation unit 22 generates a pulsed light train (third pulsed light train) L3 that includes a plurality of pulsed light trains (second pulsed light trains) L2 by performing wavelength division, propagation on multiple optical paths, and wavelength combination on the pulsed light train L1. In the present embodiment, the pulsed light train L3 includes a pulsed light train L21 and a pulsed light train L22 as the pulsed light train L2. That is, each of the plurality of pulsed light trains L2 is either the pulsed light train L21 or the pulsed light train L22.

[0035] The second light generation unit 23 and the first light generation unit 22 are arranged via the space through which the pulsed light train L3 propagates. The second light generation unit 23 is a regenerative amplifier. Specifically, the second light generation unit 23 includes a pair of mirrors 231, 232, a light extraction unit 233, a gain medium 234, and an excitation light source 235. The light extraction unit 233 and the gain medium 234 are held by the pair of mirrors 231, 232 in a juxtaposed state and form an optical resonator with respect to the pulsed light train.

[0036] The optical extraction unit 233 selects at least one pulse train L2 from among a plurality of pulse trains L2 in the pulse train L3 emitted from the first light generation unit 22. Thereby, the optical extraction unit 233 generates a pulse train (fourth pulse train) L4 including at least one pulse train L2. Specifically, the pulse train L3 passes through the mirror 231 and is input to the optical extraction unit 233. Based on the control signal C, the optical extraction unit 233 selects the pulse train L21 or the pulse train L22 from among the plurality of pulse trains L2 in the pulse train L3.

[0037] When the optical extraction unit 233 receives the control signal C1 from the control unit 24, it allows the pulse train L21 included in the pulse train L3 to pass through and blocks the pulse train L22 included in the pulse train L3, thereby generating a pulse train L4 including only the pulse train L21. Further, when the optical extraction unit 233 receives the control signal C2 from the control unit 24, it blocks the pulse train L21 included in the pulse train L3 and allows the pulse train L22 included in the pulse train L3 to pass through, thereby generating a pulse train L4 including only the pulse train L22. The pulse train L4 generated by the optical extraction unit 233 is amplified in the regenerative amplifier, i.e., the second light generation unit 23, and the amplified pulse train L4A is emitted from the second light generation unit 23.

[0038] The gain medium 234 is disposed on the resonant optical path of the optical resonator and receives the supply of excitation energy from the excitation light source 235 to amplify light. The gain medium 234 includes Yb:YAG or the like. The excitation light source 235 irradiates the gain medium 234 with excitation light as excitation energy.

[0039] The regenerative amplifier will be described in more detail. The optical extraction unit 233 includes an electro-optical element (not shown), a λ / 4 wavelength plate (not shown), a polarization beam splitter (not shown), etc., which are respectively disposed on the optical path of the optical resonator. The electro-optical element is, for example, a Pockels cell, and controls the polarization state of light through the electro-optical effect. The λ / 4 wavelength plate gives a 90° phase difference between the polarization components of light. The polarization beam splitter selectively reflects or transmits light according to their polarization states.

[0040] The pulsed light train L4 is reflected by the polarization beam splitter and introduced into the optical resonator. Inside the optical resonator, the pulsed light train L4 passes through a λ / 4 wavelength plate and an electro-optical element, is reflected by the mirror 231, and then returns to the polarization beam splitter again. During the period from when the pulsed light train L4 is reflected by the polarization beam splitter until it returns to the polarization beam splitter again, a driving voltage is applied to the electro-optical element. Thereby, the Q value of the optical resonator instantaneously increases, and the pulsed light train L4 resonates inside the optical resonator. The pulsed light train L4 resonates and absorbs the energy of the gain medium 234, gradually amplifies, and increases the peak power. After a predetermined time has elapsed since the pulsed light train L4 was enclosed in the optical resonator, a change is given to the voltage applied to the electro-optical element. Thereby, the amplified pulsed light train L4A has its polarization state changed and is taken out to the outside of the optical resonator and emitted to the outside of the laser processing light source 2.

[0041] The control unit 24 controls the operations of the respective parts of the laser processing light source 2. The control unit 24 includes a processing unit and a storage unit, etc. The processing unit is configured as a computer device including a processor, a memory, a storage, and a communication device, etc. In the processing unit, the processor executes software (program) read into the memory, etc., and controls the reading and writing of data in the memory and the storage, as well as communication using the communication device. The storage unit is, for example, a hard disk, etc., and stores various data.

[0042] The control unit 24 controls the second light generation unit 23. Specifically, the control unit 24 receives the electrical signal E from the laser oscillation unit 21. The control unit 24 generates a control signal C based on the electrical signal E. The control signal C is a signal for selecting at least one pulsed light train L2 from among the multiple pulsed light trains L2 in the pulsed light train L3. In the present embodiment, the control signal C is the control signal C1 for selecting the pulsed light train L21 or the control signal C2 for selecting the pulsed light train L22. Each of the control signal C1 and the control signal C2 is a pulsed signal having the same frequency as the electrical signal E. The control unit 24 sends the control signal C1 or the control signal C2 to the light extraction unit 233.

[0043] The control signal C1 is generated based on the optical path length of the optical path in which the pulsed light train L21 is generated in the optical path from the laser oscillation unit 21 to the light extraction unit 233. When the control signal C1 is sent to the light extraction unit 233, the pulsed light train L21 is extracted from the pulsed light train L3 input to the light extraction unit 233. The control signal C2 is generated based on the optical path length of the optical path in which the pulsed light train L22 is generated in the optical path from the laser oscillation unit 21 to the light extraction unit 233. When the control signal C2 is sent to the light extraction unit 233, the pulsed light train L22 is extracted from the pulsed light train L3 input to the light extraction unit 233. In addition, the control signal C2 has a time difference ΔC delay with respect to the control signal C1.

[0044] The user interface 25 has, for example, an input reception unit that receives various data from an operator. The operator can input data for selecting, for example, the pulsed light train L21 or the pulsed light train L22 into the user interface 25. The user interface 25 sends this data to the control unit 24.

[0045] The first light generation unit 22 will be described in more detail. As Figure 3 shown, the first light generation unit 22 includes a plurality of couplers 71, 72, 73, 74, and a plurality of optical fibers F1, F2, F3, F4, F5, F6. The plurality of optical fibers F2, F3, F4, F5, F6 connect the couplers adjacent to each other on the optical path.

[0046] One input end of the coupler 71 (the first wavelength division unit) is connected to the laser oscillation unit 21 through the optical fiber F1. The other input end of the coupler 71 is subjected to termination processing. One output end of the coupler 71 is connected to one input end of the coupler 72 (the second wavelength division unit) through the optical fiber F2. The other output end of the coupler 71 is connected to the other input end of the coupler 74 (the first wavelength multiplexing unit) through the optical fiber F3. The other input end of the coupler 72 is subjected to termination processing. One output end of the coupler 72 is connected to one input end of the coupler 73 (the second wavelength multiplexing unit) through the optical fiber F4. The other output end of the coupler 72 is connected to the other input end of the coupler 73 through the optical fiber F5. One output end of the coupler 73 is connected to one input end of the coupler 74 through the optical fiber F6. The other output end of the coupler 73 is subjected to termination processing. One output end of the coupler 74 is open. That is, no optical fiber is connected to one output end of the coupler 74. The other output end of the coupler 74 is subjected to termination processing.

[0047] In the first light generation unit 22, the first optical path is formed by the couplers 72, 73 and the optical fibers F2, F4, F5, F6, and the second optical path is formed by the optical fiber F3. Further, the third optical path is formed by the optical fiber F4, and the fourth optical path is formed by the optical fiber F5. The optical path length of the first optical path is different from the optical path length of the second optical path. The optical path length of the second optical path is greater than the optical path length of the first optical path. The optical path length of the third optical path is different from the optical path length of the fourth optical path. The optical path length of the fourth optical path is greater than the optical path length of the third optical path.

[0048] The coupler 71 demultiplexes the pulsed light train L1 into two pulsed light trains. The first optical path and the second optical path each propagate the two pulsed light trains. The coupler 74 generates a pulsed light train L3 by multiplexing the two pulsed light trains propagating in the first optical path and the second optical path. The coupler 72 demultiplexes one of the two pulsed light trains demultiplexed by the coupler 71 into two sub-pulsed light trains. The third optical path and the fourth optical path each propagate the two sub-pulsed light trains. The coupler 73 multiplexes the two sub-pulsed light trains propagating in the third optical path and the fourth optical path. The coupler 74 generates a pulsed light train L3 by multiplexing the other of the two pulsed light trains demultiplexed by the coupler 71 and the pulsed light train multiplexed by the coupler 73.

[0049] Specifically, the pulsed light train L1 emitted from the laser oscillation unit 21 propagates in the optical fiber F1 and is incident on the coupler 71. The pulsed light train L1 is demultiplexed into a pulsed light train L21 and a pulsed light train L23 by the coupler 71. The pulsed light train L21 propagates in the optical fiber F3 and is incident on the coupler 74. The pulsed light train L23 propagates in the optical fiber F2 and is incident on the coupler 72. The pulsed light train L23 is demultiplexed into a pulsed light train (sub-pulsed light train) L24 and a pulsed light train (sub-pulsed light train) L25 by the coupler 72. The pulsed light train L24 propagates in the optical fiber F4 and is incident on the coupler 73. The pulsed light train L25 propagates in the optical fiber F5 and is incident on the coupler 73. The pulsed light train L24 and the pulsed light train L25 are multiplexed into a pulsed light train L22 by the coupler 73. The pulsed light train L22 propagates in the optical fiber F6 and is incident on the coupler 74. The pulsed light train L22 and the pulsed light train L21 are multiplexed by the coupler 74. Thus, a pulsed light train L3 containing two pulsed light trains L2 is generated.

[0050] As described above, the optical path length of the fourth optical path (i.e., the optical path length of the optical fiber F5) is greater than the optical path length of the third optical path (i.e., the optical path length of the optical fiber F4). Therefore, the phase of the pulsed light train L25 emitted from the fourth optical path is delayed with respect to the phase of the pulsed light train L24 emitted from the third optical path. Therefore, in the pulsed light train L22 multiplexed by the coupler 73, the light of one pulse becomes a double-pulsed light composed of two pulses arranged with a time difference τ1. The time difference τ1 is a value obtained by dividing the optical path difference between the third optical path and the fourth optical path by the speed of light, and is, for example, about several hundred ps. In this way, the pulsed light train L22 is a double-pulsed light train composed of multiple double-pulsed lights. In addition, the double-pulsed light refers to the light of one pulse composed of two pulses that are temporally close to each other, for example, from several ps to 20 ns.

[0051] In addition, the optical path length of the second optical path (i.e., the optical path length of optical fiber F3) is greater than the optical path length of the first optical path (i.e., the optical path lengths of the optical paths formed by couplers 72, 73 and optical fibers F2, F4, F6, and the optical path lengths of the optical paths formed by couplers 72, 73 and optical fibers F2, F5, F6). Therefore, the phase of the pulsed light train L21 emitted from the second optical path is delayed with respect to the phase of the pulsed light train L22 emitted from the first optical path. Therefore, in the pulsed light train L3 multiplexed by coupler 74, the multiple single pulsed lights included in the pulsed light train L21 and the multiple double pulsed lights included in the pulsed light train L22 are alternately arranged with a time difference τ2. The time difference τ2 is a value obtained by dividing the optical path difference between the first optical path and the second optical path by the speed of light, and is about 12.5 ns, for example. The time difference τ2 is the same as the time difference ΔC. In addition, a single pulsed light refers to a single-pulse light composed of one pulse.

[0052] An example of the frequency and power (the power of a single pulsed light) of each pulsed light train will be described. The pulsed light train L1 having a frequency of 40 MHz and a power of 100 mW is demultiplexed by coupler 71 into a pulsed light train L23 having a frequency of 40 MHz and a power of 80 mW, and a pulsed light train L21 having a frequency of 40 MHz and a power of 20 mW. The pulsed light train L23 having a frequency of 40 MHz and a power of 80 mW is demultiplexed by coupler 72 into a pulsed light train L24 having a frequency of 40 MHz and a power of 40 mW, and a pulsed light train L25 having a frequency of 40 MHz and a power of 40 mW.

[0053] The pulsed light train L24 having a frequency of 40 MHz and a power of 40 mW and the pulsed light train L25 having a frequency of 40 MHz and a power of 40 mW are multiplexed by coupler 73 into a pulsed light train L22 having a frequency of 40 MHz and a power of 40 mW. The pulsed light train L22 having a frequency of 40 MHz and a power of 40 mW and the pulsed light train L21 having a frequency of 40 MHz and a power of 20 mW are multiplexed by coupler 74 into a pulsed light train L3 having a frequency of 80 MHz and a power of 30 mW. In addition, the pulsed light train L4A (refer to Figure 2 ) amplified in the second light generation unit 23 which is a regenerative amplifier and emitted from the second light generation unit 23 has a frequency of 20 to 500 kHz and a power of 4 to 20 W.

[0054] As described above, in the laser processing light source 2, a pulsed light train L3 including a plurality of pulsed light trains L2 is generated. In the pulsed light train L3, the pulsed light train L21 or the pulsed light train L22 is selected from the plurality of pulsed light trains L2. Thereby, a pulsed light train L4 including the pulsed light train L21 or the pulsed light train L22 is generated. Therefore, according to the laser processing light source 2, a variety of pulsed light trains can be selectively emitted.

[0055] There are cases where one seeks to emit both a double-pulse optical train and a single-pulse optical train with a time difference of about several hundred picoseconds from the same light source for laser processing. Therefore, the inventors of the present invention have discovered the above-described light source 2 for laser processing. That is, according to the light source 2 for laser processing, it is possible to provide a device that can switch and emit a double-pulse optical train and a single-pulse optical train by changing only the control signal C without changing the hardware, and that is highly reliable, highly stable, and highly efficient for industrial use. In addition, it has been confirmed that the optical characteristics (average output, energy stability, beam pattern) during the output of the single-pulse optical train are maintained even during the output of the double-pulse optical train. Further, according to the light source 2 for laser processing, it is possible to cause existing processing optical systems such as the irradiation optical system 3 to continue to function, and to perform processing using a double-pulse optical train by simply replacing the light source 2 for laser processing.

[0056] In addition, in the light source 2 for laser processing, the laser oscillation unit 21 transmits an electrical signal E having a frequency corresponding to the pulse train L1 to the control unit 24. The control unit 24 generates a control signal C based on the electrical signal E. According to this configuration, it is possible to correctly and easily control the second light generation unit 23 that selects the pulse train L21 or the pulse train L22 from among the plurality of pulse trains L2 in the pulse train L3.

[0057] In addition, in the light source 2 for laser processing, the second light generation unit 23 is a regenerative amplifier, which includes: a light extraction unit 233 that generates a pulse train L4; a gain medium 234 that, together with the light extraction unit 233, forms an optical resonator with respect to the pulse train L4; and an excitation light source 235 that irradiates the gain medium 234 with excitation light. According to this configuration, it is possible to effectively generate and amplify the pulse train L4.

[0058] In addition, in the light source 2 for laser processing, each of the plurality of pulse trains L2 is a single-pulse optical train (pulse train L21) and a double-pulse optical train (pulse train L22). According to this configuration, in the pulse train L3, for example, a single-pulse optical train or a double-pulse optical train is selected from among the plurality of pulse trains L2, whereby a pulse train L4 including a single-pulse optical train or a double-pulse optical train can be generated.

[0059] In addition, in the light source 2 for laser processing, the first light generation unit 22 includes a coupler 71, a first optical path and a second optical path, and a coupler 74. The coupler 71 splits the pulse light train L1 into two pulse light trains L21 and L23. The first optical path and the second optical path have different optical path lengths and propagate the two pulse light trains L21 and L23 respectively. The coupler 74 combines the two pulse light trains L21 and L22 to generate a pulse light train L3. The first optical path includes a coupler 72, a third optical path and a fourth optical path, and a coupler 73. The coupler 72 splits the pulse light train L23 split by the coupler 71 into two pulse light trains L24 and L25. The third optical path and the fourth optical path have different optical path lengths and propagate the two pulse light trains L24 and L25 respectively. The coupler 73 combines the two pulse light trains L24 and L25. The coupler 74 combines the pulse light train L21 split by the coupler 71 and the pulse light train L22 combined by the coupler 73 to generate a pulse light train L3. With this structure, the generation of the pulse light train L3 can be easily performed.

[0060] In addition, in the light source 2 for laser processing, the first splitting unit, the first combining unit, the second splitting unit, and the second combining unit are the couplers 71, 72, 73, and 74 respectively. The first light generation unit 22 includes optical fibers F2, F3, F4, F5, and F6 that connect the couplers adjacent to each other on the optical path. With this structure, the generation of the pulse light train L3 can be performed more easily.

[0061] That is, the first light generation unit 22 is composed of widely used fiber optic components, so active control or special optical elements are not required. As a result, a cheap, highly reliable, and highly stable structure can be achieved. In addition, compared with the case where the first light generation unit is constituted by, for example, a polarization beam splitter, the optical characteristics can be improved. That is, the polarization directions of the double pulse light trains, that is, the pulse light train L22, are the same, so a decrease in the light utilization efficiency caused by adjusting the polarization state, for example, can be suppressed. In addition, an increase in the distance from the laser oscillation unit 21 to the workpiece P is suppressed, so a decrease in the long-term stability of the device is suppressed. In addition, regular alignment adjustment is not required. In addition, the pulse light trains L22 propagate in exactly the same optical path, so it is not necessary to make multiple lights coincide exactly at the focal point.

[0062] In addition, in the light source 2 for laser processing, the first light generation unit 22 and the second light generation unit 23 are arranged via the space through which the pulse light train L3 propagates. With this structure, the first light generation unit 22 can be easily loaded and unloaded independently of the second light generation unit 23.

[0063] According to the laser processing apparatus 1, various pulse light trains L4 can be selectively irradiated to the workpiece P. Thus, the workpiece P can be appropriately processed according to various uses.

[0064] [Second Embodiment]

[0065] As Figure 4 shown, the light source for laser processing of the second embodiment is different from the light source for laser processing of the first embodiment mainly in that the first light generation unit 22A is provided in place of the first light generation unit 22. The first light generation unit 22A includes a plurality of couplers 81 to 88 and a plurality of optical fibers F11 to F22. The plurality of optical fibers F12 to F22 connect the couplers adjacent to each other on the optical path.

[0066] One input end of the coupler 81 is connected to the laser oscillation unit 21 through the optical fiber F11. The other input end of the coupler 81 is subjected to termination processing. One output end of the coupler 81 is connected to one input end of the coupler 82 through the optical fiber F12. The other output end of the coupler 81 is connected to the other input end of the coupler 86 through the optical fiber F13. The other input end of the coupler 82 is subjected to termination processing. One output end of the coupler 82 is connected to one input end of the coupler 83 through the optical fiber F14. The other output end of the coupler 82 is connected to one input end of the coupler 87 through the optical fiber F15.

[0067] The other input end of the coupler 83 is subjected to termination processing. One output end of the coupler 83 is connected to one input end of the coupler 84 through the optical fiber F16. The other output end of the coupler 83 is connected to the other input end of the coupler 84 through the optical fiber F17. One output end of the coupler 84 is connected to one input end of the coupler 85 through the optical fiber F18. The other output end of the coupler 84 is subjected to termination processing.

[0068] The other input end of the coupler 87 is subjected to termination processing. One output end of the coupler 87 is connected to one input end of the coupler 88 through the optical fiber 20. The other output end of the coupler 87 is connected to the other input end of the coupler 88 through the optical fiber F21. One output end of the coupler 88 is connected to the other input end of the coupler 85 through the optical fiber F22. The other output end of the coupler 88 is subjected to termination processing.

[0069] One output end of the coupler 85 is connected to one input end of the coupler 86 through the optical fiber F19. The other output end of the coupler 85 is subjected to termination processing. One output end of the coupler 86 is open. That is, no optical fiber is connected to one output end of the coupler 86. The other output end of the coupler 86 is subjected to termination processing.

[0070] In the first light generation unit 22A, a first optical path is formed by couplers 82, 83, 84, 85 and optical fibers F12, F14, F16, F17, F18, F19, and a second optical path is formed by optical fiber F13. In addition, a third optical path is formed by optical fiber F16, and a fourth optical path is formed by optical fiber F17. In addition, a fifth optical path is formed by couplers 87, 88 and optical fibers F15, F20, F21, F22, and an eighth optical path is formed by couplers 83, 84 and optical fibers F14, F16, F17, F18. In addition, a sixth optical path is formed by optical fiber F20, and a seventh optical path is formed by optical fiber F21.

[0071] The optical path lengths of the first optical path and the second optical path are different from each other. The optical path length of the second optical path is greater than that of the first optical path. The optical path lengths of the third optical path and the fourth optical path are different from each other. The optical path length of the fourth optical path is greater than that of the third optical path. The optical path lengths of the fifth optical path and the eighth optical path are different from each other. The optical path length of the fifth optical path is greater than that of the eighth optical path. The optical path lengths of the sixth optical path and the seventh optical path are different from each other. The optical path length of the seventh optical path is greater than that of the sixth optical path.

[0072] The pulsed light train L1 emitted from the laser oscillation unit 21 propagates in the optical fiber F11 and is incident on the coupler 81. The pulsed light train L1 is split by the coupler 81 into a pulsed light train L31 (pulsed light train L2) and a pulsed light train L34. The pulsed light train L31 propagates in the optical fiber F13 and is incident on the coupler 86. The pulsed light train L34 propagates in the optical fiber F12 and is incident on the coupler 82.

[0073] The pulsed light train L34 is split by the coupler 82 into a pulsed light train L35 and a pulsed light train L36. The pulsed light train L35 propagates in the optical fiber F14 and is incident on the coupler 83. The pulsed light train L35 is split by the coupler 83 into a pulsed light train (sub-pulsed light train) L37 and a pulsed light train (sub-pulsed light train) L38. The pulsed light train L37 propagates in the optical fiber F16 and is incident on the coupler 84. The pulsed light train L38 propagates in the optical fiber F17 and is incident on the coupler 84. The pulsed light train L37 and the pulsed light train L38 are combined by the coupler 84 into a pulsed light train L32 (pulsed light train L2). The pulsed light train L32 propagates in the optical fiber F18 and is incident on the coupler 85.

[0074] The pulsed light train L36 propagates in the optical fiber F15 and is incident on the coupler 87. The pulsed light train L36 is split by the coupler 87 into a pulsed light train (sub-pulsed light train) L39 and a pulsed light train (sub-pulsed light train) L40. The pulsed light train L39 propagates in the optical fiber F20 and is incident on the coupler 88. The pulsed light train L40 propagates in the optical fiber F21 and is incident on the coupler 88. The pulsed light trains L39 and L40 are multiplexed by the coupler 88 into a pulsed light train L33 (pulsed light train L2). The pulsed light train L33 propagates in the optical fiber F22 and is incident on the coupler 85.

[0075] The pulsed light trains L32 and L33 are multiplexed by the coupler 85 into a pulsed light train L30. The pulsed light train L30 propagates in the optical fiber F19 and is incident on the coupler 86. The pulsed light train 31 and the pulsed light train L30 are multiplexed by the coupler 86 into a pulsed light train L3. Thus, a pulsed light train L3 containing three pulsed light trains L2 is generated.

[0076] As described above, the optical path length of the fourth optical path (i.e., the optical path length of the optical fiber F17) is greater than the optical path length of the third optical path (i.e., the optical path length of the optical fiber F16). Therefore, the phase of the pulsed light train L38 emitted from the fourth optical path is delayed with respect to the phase of the pulsed light train L37 emitted from the third optical path. Therefore, in the pulsed light train L32 multiplexed by the coupler 84, the light of one pulse becomes a double-pulse light composed of two pulses arranged with a time difference τ3. The time difference τ3 is a value obtained by dividing the optical path difference between the third optical path and the fourth optical path by the speed of light, and is about several hundred ps, for example. In this way, the pulsed light train L32 is a double-pulse light train composed of multiple double-pulse lights.

[0077] Similarly, the optical path length of the seventh optical path (i.e., the optical path length of the optical fiber F21) is greater than the optical path length of the sixth optical path (i.e., the optical path length of the optical fiber F20). Therefore, the phase of the pulsed light train L40 emitted from the seventh optical path is delayed with respect to the phase of the pulsed light train L39 emitted from the sixth optical path. Therefore, in the pulsed light train L33 multiplexed by the coupler 88, the light of one pulse becomes a double-pulse light composed of two pulses arranged with a time difference τ4. The time difference τ4 is a value obtained by dividing the optical path difference between the sixth optical path and the seventh optical path by the speed of light, and is about several hundred ps, for example. In this way, the pulsed light train L33 is a double-pulse light train composed of multiple double-pulse lights.

[0078] The optical path length of the fifth optical path (i.e., the optical path lengths of the optical paths formed by couplers 87, 88 and optical fibers F15, F20, F22, and the optical path lengths of the optical paths formed by couplers 87, 88 and optical fibers F15, F21, F22) is greater than the optical path length of the eighth optical path (i.e., the optical path lengths of the optical paths formed by couplers 83, 84 and optical fibers F14, F16, F18, and the optical path lengths of the optical paths formed by couplers 83, 84 and optical fibers F14, F17, F18). Therefore, the phase of the pulsed light train L33 emitted from the fifth optical path is delayed with respect to the phase of the pulsed light train L32 emitted from the eighth optical path. Therefore, in the pulsed light train L30 multiplexed by the coupler 85, a plurality of double pulsed lights included in the pulsed light train L32 and a plurality of double pulsed lights included in the pulsed light train L33 are alternately arranged with a time difference τ5. The time difference τ5 is a value obtained by dividing the optical path difference between the fifth optical path and the eighth optical path by the speed of light, and is about 8.3 ns, for example.

[0079] Similarly, the optical path length of the second optical path (i.e., the optical path length of the optical path formed by the optical fiber F13) is greater than the optical path length of the first optical path (i.e., the optical path lengths of the optical paths formed by couplers 82, 83, 84, 85 and optical fibers F12, F14, F16, F18, F19, and the optical path lengths of the optical paths formed by couplers 82, 83, 84, 85 and optical fibers F12, F14, F17, F18, F19). Therefore, the phase of the pulsed light train L31 emitted from the second optical path is delayed with respect to the phase of the pulsed light train L30 emitted from the first optical path. Therefore, in the pulsed light train L3 multiplexed by the coupler 86, a plurality of double pulsed lights included in the pulsed light train L31 and a plurality of double pulsed lights included in the pulsed light train L30 are alternately arranged with a time difference τ6. The time difference τ6 is a value obtained by dividing the optical path difference between the first optical path and the second optical path by the speed of light, and is about 8.3 ns, for example.

[0080] An example of the frequency and power (the power of one pulsed light) of each pulsed light train will be described. A pulsed light train L1 having a frequency of 40 MHz and a power of 100 mW is demultiplexed by a coupler 81 into a pulsed light train L34 having a frequency of 40 MHz and a power of 80 mW, and a pulsed light train L31 having a frequency of 40 MHz and a power of 20 mW. The pulsed light train L34 having a frequency of 40 MHz and a power of 80 mW is demultiplexed by a coupler 82 into a pulsed light train L35 having a frequency of 40 MHz and a power of 40 mW, and a pulsed light train L36 having a frequency of 40 MHz and a power of 40 mW.

[0081] A pulsed light train L35 with a frequency of 40 MHz and a power of 40 mW is split by a coupler 83 into a pulsed light train L37 with a frequency of 40 MHz and a power of 20 mW, and a pulsed light train L38 with a frequency of 40 MHz and a power of 20 mW. The pulsed light train L37 with a frequency of 40 MHz and a power of 20 mW, and the pulsed light train L38 with a frequency of 40 MHz and a power of 20 mW are combined by a coupler 84 into a pulsed light train L32 with a frequency of 40 MHz and a power of 20 mW.

[0082] A pulsed light train L36 with a frequency of 40 MHz and a power of 40 mW is split by a coupler 87 into a pulsed light train L39 with a frequency of 40 MHz and a power of 20 mW, and a pulsed light train L40 with a frequency of 40 MHz and a power of 20 mW. The pulsed light train L39 with a frequency of 40 MHz and a power of 20 mW, and the pulsed light train L40 with a frequency of 40 MHz and a power of 20 mW are combined by a coupler 88 into a pulsed light train L33 with a frequency of 40 MHz and a power of 20 mW.

[0083] The pulsed light train L32 with a frequency of 40 MHz and a power of 20 mW, and the pulsed light train L33 with a frequency of 40 MHz and a power of 20 mW are combined by a coupler 85 into a pulsed light train L30 with a frequency of 80 MHz and a power of 20 mW. The pulsed light train L30 with a frequency of 80 MHz and a power of 20 mW, and the pulsed light train L31 with a frequency of 40 MHz and a power of 20 mW are combined by a coupler 86 into a pulsed light train L3 with a frequency of 120 MHz and a power of 20 mW.

[0084] [Variant Example]

[0085] The embodiments of the present invention have been described above, but the present invention is not limited to the above embodiments.

[0086] As Figure 5 shown, the light source for laser processing in the first embodiment may also include a first light generation unit 22B instead of the first light generation unit 22. The first light generation unit 22B is mainly different from the first light generation unit 22 in that it has a coupler 72B instead of the coupler 72. The branching ratio of the coupler 72B is different from the branching ratio of the coupler 72. As an example, a pulsed light train L23 with a frequency of 40 MHz and a power of 80 mW may also be split by a coupler 72B into a pulsed light train L24B with a frequency of 40 MHz and a power of 60 mW, and a pulsed light train L25B with a frequency of 40 MHz and a power of 20 mW. At this time, in the pulsed light train L22B combined by the coupler 73, the light of one pulse becomes a double-pulse light composed of two pulses with different powers.

[0087] As Figure 6 shown, the light source for laser processing according to the second embodiment may also include a first light generation unit 22C instead of the first light generation unit 22A. The first light generation unit 22C is mainly different from the first light generation unit 22A in that an optical fiber F23 is provided instead of the fifth optical path (the optical path formed by the couplers 87, 88 and the optical fibers F15, F20, F21, F22).

[0088] The other output end of the coupler 82 is connected to the other input end of the coupler 85 through the optical fiber F23. The pulsed light train L36 output from the coupler 82 propagates in the optical fiber F23 and is incident on the coupler 85. The pulsed light train L32 and the pulsed light train 36 are multiplexed into a pulsed light train L37 (pulsed light train L2) by the coupler 85. In the first light generation unit 22C, the ninth optical path is formed by the optical fiber F23. The optical path length of the ninth optical path (i.e., the optical path length of the optical fiber F23) is different from the optical path length of the eighth optical path (i.e., the optical path lengths of the optical paths formed by the couplers 83, 84 and the optical fibers F14, F16, F18, and the optical path lengths of the optical paths formed by the couplers 83, 84 and the optical fibers F14, F17, F18). The optical path length of the ninth optical path is greater than the optical path length of the eighth optical path. Therefore, in the pulsed light train L37 multiplexed by the coupler 85, the light of one pulse becomes a three-pulse light composed of, for example, three pulses arranged at the same time difference.

[0089] In each embodiment, the branching ratio of each coupler (the power ratio of each pulsed light train to be demultiplexed) and the length of each optical fiber may also be adjusted as needed.

[0090] In each embodiment, the second light generation unit 23 only needs to have at least an optical cutting unit 233. That is, the second light generation unit 23 may not be a regenerative amplifier. The second light generation unit 23 may, for example, have an optical cutting unit 233, one gain medium, and one excitation light source. That is, the second light generation unit 23 may be a single-channel amplifier. At this time, the pulsed light train L4 generated by the optical cutting unit 233 is amplified by passing through one gain medium. In addition, the second light generation unit 23 may have an optical cutting unit 233, a plurality of gain media, and a plurality of excitation light sources. That is, the second light generation unit 23 may be a MOPA amplifier. At this time, the pulsed light train L4 generated by the optical cutting unit 233 is amplified by passing through a plurality of gain media.

[0091] In each embodiment, an example in which the first light generation units 22, 22A are constituted by couplers and optical fibers is shown, but the first light generation units 22, 22A may also be constituted by an optical system such as a beam splitter. The first light generation units 22, 22A only need to generate a pulsed light train L3 including a plurality of pulsed light trains L2 by demultiplexing the pulsed light train L1, propagating on a plurality of optical paths, and multiplexing.

[0092] In each embodiment, an example is shown in which the first light generation units 22 and 22A generate the pulse light train L3 including two or three pulse light trains L2. However, the first light generation units 22 and 22A may also generate the pulse light train L3 including n (n is an integer greater than 3) pulse light trains L2. The light extraction unit 233 may also generate the pulse light train L4 including m (m is an integer equal to or less than n) pulse light trains L2 by selecting m pulse light trains L2 from the n pulse light trains L2 in the pulse light train L3. The light extraction unit 233 only needs to generate the pulse light train L4 including at least one pulse light train L2 by selecting at least one pulse light train L2 from the plurality of pulse light trains L2 in the pulse light train L3.

[0093] Description of symbols

[0094] 1... Laser processing apparatus, 2... Light source for laser processing, 3... Irradiation optical system (irradiation unit), 4... Support unit, 21... Laser oscillation unit, 22, 22A, 22B, 22C... First light generation unit, 23... Second light generation unit, 24... Control unit, 71... Coupler (first demultiplexing unit), 72... Coupler (second demultiplexing unit), 73... Coupler (second multiplexing unit), 74... Coupler (first multiplexing unit), 233... Light extraction unit, 234... Gain medium, 235... Excitation light source, C, C1, C2... Control signal, E... Electric signal, L1... Pulse light train (first pulse light train), L2... Pulse light train (second pulse light train), L3... Pulse light train (third pulse light train), L4... Pulse light train (fourth pulse light train), L21, L23... Pulse light trains, L24, L25... Pulse light trains (sub-pulse light trains), P... Workpiece.

Claims

1. A light source for laser processing, wherein: It includes: A laser oscillation unit that emits a first pulse light train; A first light generation unit that generates a third pulse light train including a variety of second pulse light trains by performing wavelength division, propagation on multiple optical paths, and wavelength combination on the first pulse light train; A second light generation unit that selects at least one second pulse light train from the variety of second pulse light trains in the third pulse light train and generates a fourth pulse light train including the at least one second pulse light train; and A control unit that controls the second light generation unit, The second light generation unit allows the at least one second pulse light train to pass through and blocks at least one other second pulse light train from the variety of second pulse light trains, and generates the fourth pulse light train including the passed second pulse light train, The control unit sends a control signal for selecting the at least one second pulse light train from the variety of second pulse light trains in the third pulse light train to the second light generation unit.

2. The light source for laser processing according to claim 1, wherein: The laser oscillation unit sends an electrical signal having a frequency corresponding to the first pulse light train to the control unit, The control unit generates the control signal based on the electrical signal.

3. The light source for laser processing according to claim 1, wherein: The second light generation unit is a regenerative amplifier having a light extraction unit, a gain medium, and an excitation light source, The light extraction unit generates the fourth pulse light train, The gain medium forms an optical resonator together with the light extraction unit with respect to the fourth pulse light train, The excitation light source irradiates the gain medium with excitation light.

4. The light source for laser processing according to claim 2, wherein: The second light generation unit is a regenerative amplifier having a light extraction unit, a gain medium, and an excitation light source, The light extraction unit generates the fourth pulse light train, The gain medium forms an optical resonator together with the light extraction unit with respect to the fourth pulse light train, The excitation light source irradiates the gain medium with excitation light.

5. The light source for laser processing according to claim 1, wherein: The variety of second pulse light trains are respectively a single-pulse light train and a double-pulse light train.

6. The light source for laser processing according to claim 2, wherein: The variety of second pulse light trains are respectively a single-pulse light train and a double-pulse light train.

7. The light source for laser processing according to claim 3, wherein: The variety of second pulse light trains are respectively a single-pulse light train and a double-pulse light train.

8. The light source for laser processing according to claim 4, wherein: The variety of second pulse light trains are respectively a single-pulse light train and a double-pulse light train.

9. The light source for laser processing according to any one of claims 1 to 8, wherein: The first light generation unit has: A first wavelength division unit that wavelength-divides the first pulse light train into two pulse light trains; A first optical path and a second optical path, whose optical path lengths are different from each other, and each of the two pulse light trains propagates through them; and A first wavelength combination unit that generates the third pulse light train by wavelength-combining the two pulse light trains, The first optical path has: A second wavelength division unit that wavelength-divides one of the two pulsed light trains wavelength-divided by the first wavelength division unit into two sub-pulsed light trains; A third optical path and a fourth optical path, which have different optical path lengths from each other and propagate each of the two sub-pulsed light trains; and A second multiplexing unit that multiplexes the two sub-pulsed light trains, The first multiplexing unit generates the third pulsed light train by multiplexing the other of the two pulsed light trains wavelength-divided by the first wavelength division unit and the pulsed light train multiplexed by the second multiplexing unit.

10. The light source for laser processing according to claim 9, wherein The first wavelength division unit, the first multiplexing unit, the second wavelength division unit, and the second multiplexing unit are each a coupler, The first light generation unit further includes an optical fiber that connects the couplers adjacent to each other on the optical path.

11. The light source for laser processing according to any one of claims 1 to 8, wherein The first light generation unit and the second light generation unit are arranged via the space through which the third pulsed light train propagates.

12. The light source for laser processing according to claim 9, wherein The first light generation unit and the second light generation unit are arranged via the space through which the third pulsed light train propagates.

13. The light source for laser processing according to claim 10, wherein The first light generation unit and the second light generation unit are arranged via the space through which the third pulsed light train propagates.

14. A light source for laser processing, wherein It includes: A laser oscillation unit that emits a first pulsed light train; A first light generation unit that generates a third pulsed light train including a plurality of second pulsed light trains by performing wavelength division, propagation on a plurality of optical paths, and multiplexing on the first pulsed light train; A second light generation unit that selects at least one second pulsed light train from the plurality of second pulsed light trains in the third pulsed light train and generates a fourth pulsed light train including the at least one second pulsed light train; and A control unit that controls the second light generation unit, The control unit sends a control signal for selecting the at least one second pulsed light train from the plurality of second pulsed light trains in the third pulsed light train to the second light generation unit, The first light generation unit has: A first wavelength division unit that wavelength-divides the first pulsed light train into two pulsed light trains; A first optical path and a second optical path, which have different optical path lengths from each other and propagate each of the two pulsed light trains; and A first multiplexing unit that generates the third pulsed light train by multiplexing the two pulsed light trains, The first optical path has: A second wavelength division unit that wavelength-divides one of the two pulsed light trains wavelength-divided by the first wavelength division unit into two sub-pulsed light trains; A third optical path and a fourth optical path, which have different optical path lengths from each other and propagate each of the two sub-pulsed light trains; and A second multiplexing unit that multiplexes the two sub-pulsed light trains, The first multiplexing unit generates the third pulsed light train by multiplexing the other of the two pulsed light trains wavelength-divided by the first wavelength division unit and the pulsed light train multiplexed by the second multiplexing unit.

15. A laser processing apparatus, wherein It includes: The light source for laser processing according to any one of claims 1 to 14; A support part that supports the workpiece; and An irradiation part that irradiates the workpiece with a pulsed light train emitted from the laser processing light source.

Images