Laser device, laser machining device, and waveform control method
Patent Information
- Application Number
- PCT/JP2025/045718
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2025-03-26
- Filing Date
- 2025-12-25
- Publication Date
- 2026-10-01
Smart Images
Figure JP2025045718_01102026_PF_FP_ABST
Abstract
Description
Laser device, laser processing apparatus and waveform control method
[0001] The present disclosure relates to a laser device, a laser processing apparatus and a waveform control method.
[0002] Laser devices that output high-power laser light are widely used for purposes such as processing materials. For example, in a laser processing apparatus that processes a material by irradiating laser light, the workpiece is irradiated with pulsed laser light. At this time, since the pulse waveform of the laser light affects the processing of the workpiece, it is required to control the waveform of the laser light to a desired waveform.
[0003] Since manually adjusting the waveform of the laser light output from a laser device requires a long adjustment time, methods for automatically performing waveform adjustment have been proposed. For example, Patent Document 1 discloses a laser device in which, after light output from a semiconductor laser element is amplified by an optical amplifier, the waveform after amplification is acquired, and the waveform of light output from the semiconductor laser element is preset such that the acquired waveform becomes a desired waveform.
[0004] Japanese Unexamined Patent Publication No. 2020-53423
[0005] In applications requiring high-output laser light such as laser processing, in order to increase the intensity of laser light, a laser device may repeatedly amplify laser light with a plurality of optical amplifiers connected in multiple stages in series. In this case, in order to adjust the waveform of the laser light output from the final stage to a desired waveform, it is required to preset the waveform of the laser light output from the light source so as to compensate for distortion of the laser light caused by amplification in the plurality of multistage-connected optical amplifiers.
[0006] However, Patent Document 1 only discloses waveform control in a laser device that amplifies the laser with a single optical amplifier. Therefore, the waveform control disclosed in Patent Document 1 does not even consider waveform control in a laser device that amplifies the laser light with multiple optical amplifiers connected in multiple stages. Furthermore, when laser light is amplified with multiple optical amplifiers, distortion due to amplification accumulates, so it is difficult to preset the waveform of the laser light output from the light source in a way that corrects the accumulated distortion using the method described in Patent Document 1.
[0007] A laser device according to one aspect of this embodiment is a laser device comprising: [1] a laser light source that outputs laser light; a plurality of optical amplifiers connected in series in multiple stages that stepwise amplify the laser light output from the laser light source; an optical detection means that detects the laser light amplified by the plurality of optical amplifiers and outputs a detection signal indicating the detection result; and a control unit that sequentially acquires a part or all of the waveform of the laser light amplified by the plurality of optical amplifiers based on the detection signal, from the front stage to the back stage of the multi-stage connection, and controls the waveform of the laser light output from the laser light source so that each of the sequentially acquired waveforms becomes a desired waveform, thereby shaping the waveform of the laser light amplified by the last stage optical amplifier to become the desired waveform.
[0008] A laser apparatus according to one aspect of this embodiment is [2] "the laser apparatus according to [1], wherein the control unit acquires the waveform of the laser light amplified by the last stage optical amplifier and any number of optical amplifiers between the first stage optical amplifier and the optical amplifier immediately preceding the last stage optical amplifier, sequentially from the front to the back of the multi-stage connection."
[0009] A laser apparatus according to one aspect of this embodiment is [3] "a laser apparatus according to [1] or [2], comprising a plurality of optical transmission paths for transmitting laser light amplified by the plurality of optical amplifiers to the optical detection means, each, and a plurality of optical attenuators inserted in each of the plurality of optical transmission paths."
[0010] A laser apparatus according to one aspect of this embodiment is [4] "the laser apparatus according to [3] in which the optical attenuator has a greater attenuation amount the more laser light amplified by the subsequent optical amplifier is incident on it."
[0011] A laser apparatus according to one aspect of this embodiment is [5] "a laser apparatus according to [1] or [2], comprising a plurality of optical transmission paths for transmitting laser light amplified by the plurality of optical amplifiers, the optical detection means includes a plurality of photodetectors that detect laser light amplified by the plurality of optical amplifiers incident through the plurality of optical transmission paths and output a plurality of signals indicating the detection result as the detection signals, and the control unit acquires a part or all of the waveform of the laser light amplified by the plurality of optical amplifiers sequentially from the preceding stage to the succeeding stage of the multi-stage connection based on the plurality of signals."
[0012] One embodiment of this laser apparatus is [6] "a laser apparatus according to [1] or [2], comprising: a plurality of optical transmission paths each transmitting laser light amplified by the plurality of optical amplifiers; an optical multiplexer into which the laser light amplified by the plurality of optical amplifiers is incident, the incident laser light is combined and output to the optical detection means, the optical detection means outputs the detection result of the laser light combined by the optical multiplexer as the detection signal, the laser light amplified by the plurality of optical amplifiers is incident on the optical detection means discretely so that their waveforms do not overlap, and the control unit acquires part or all of the waveforms of the laser light amplified by the plurality of optical amplifiers sequentially from the front to the back of the multi-stage connection based on the discrete and continuous waveforms corresponding to the laser light detected by the optical detection means, which are acquired based on the detection signal, the laser apparatus according to [1] or [2]."
[0013] A laser apparatus according to one aspect of this embodiment is [7] "In the multi-stage connection, the delay amount of the laser light incident on the optical multiplexer via the optical transmission path connected to the later optical amplifier among the two adjacent optical amplifiers is greater than the width of the pulse waveform of the laser light, as described in any one of [1] to [6]."
[0014] A laser apparatus according to one aspect of this embodiment is [8] "a laser apparatus according to any one of [1] to [7], comprising a plurality of optical delay devices inserted in each of the plurality of optical transmission paths."
[0015] A laser apparatus according to one aspect of this embodiment is [9] "In the multi-stage connection, the amount of delay of the laser light incident on the optical multiplexer via the optical transmission path and optical delay device connected to the later optical amplifier among the two adjacent optical amplifiers is greater than the width of the pulse waveform of the laser light, as described in [8]."
[0016] A laser apparatus according to one aspect of this embodiment is
[10] "a laser apparatus according to any one of [1] to [9], wherein each of the plurality of optical amplifiers has a variable gain."
[0017] A laser apparatus according to one aspect of this embodiment is
[11] "the laser apparatus according to
[10] , wherein the control unit changes the gain of the optical amplifier to be observed among the plurality of optical amplifiers toward a desired gain, and each time the gain is changed, the waveform of the laser light amplified by the optical amplifier to be observed is shaped into the desired waveform."
[0018] A laser processing apparatus according to one aspect of this embodiment is
[12] "a laser processing apparatus comprising the laser apparatus described in any one of [1] to
[11] , a drivable stage for holding a workpiece, an optical system for focusing the laser light output from the laser apparatus onto the workpiece held on the stage, and a control device for controlling the output of the laser light from the laser apparatus and the driving of the stage."
[0019] A waveform control method according to one aspect of this embodiment is
[13] "a waveform control method that outputs laser light to a plurality of optical amplifiers connected in series in multiple stages, the plurality of optical amplifiers amplify the input laser light in stages, detects each of the laser light amplified by the plurality of optical amplifiers, outputs a detection signal indicating the detection result, acquires part or all of the waveform of the laser light amplified by the plurality of optical amplifiers sequentially from the front to the back of the multi-stage connection based on the detection signal, and controls the waveform of the laser light input to the plurality of optical amplifiers so that each of the sequentially acquired waveforms becomes a desired waveform, thereby shaping the waveform of the laser light amplified by the last stage optical amplifier to become the desired waveform."
[0020] According to this disclosure, it is possible to provide a laser device, a laser processing device, and a waveform control method that can control the waveform of laser light amplified by multiple optical amplifiers connected in multiple stages.
[0021] This is a schematic diagram showing the configuration of a laser processing apparatus. This is a schematic diagram showing the configuration of a laser apparatus according to Embodiment 1. This is a flowchart showing the waveform control operation in the laser apparatus according to Embodiment 1. This is a diagram showing the waveform of laser light in the initial stage. This is a diagram showing the waveform of laser light after waveform control based on the laser light amplified by the first stage optical amplifier. This is a diagram showing the waveform of laser light after waveform control based on the laser light amplified by the second stage optical amplifier. This is a diagram showing the waveform of laser light after waveform control based on the laser light amplified by the last stage optical amplifier. This is a flowchart showing a modified example of the waveform control operation in the laser apparatus according to Embodiment 1. This is a schematic diagram showing the configuration of a laser apparatus according to Embodiment 2. This is a schematic diagram showing the configuration of a laser apparatus according to Embodiment 3. This is a flowchart showing the waveform control operation in the laser apparatus according to Embodiment 3. This is a schematic diagram showing the configuration of a laser apparatus according to Embodiment 4. This is a schematic diagram showing the configuration of a laser apparatus according to Embodiment 5. This is a flowchart showing the waveform control operation in the laser apparatus according to Embodiment 5.
[0022] The present invention will be described below through embodiments of the invention, but the invention claimed is not limited to the following embodiments. Furthermore, not all of the configurations described in the embodiments are necessarily essential as means for solving the problem. Embodiments of the present invention will be described below with reference to the drawings, in which the same elements are denoted by the same reference numerals, and redundant explanations are omitted as necessary. In addition, some figures may show a three-dimensional Cartesian coordinate system defined by mutually orthogonal X, Y, and Z axes.
[0023] Embodiment 1 First, as a prerequisite for understanding the laser apparatus according to the following embodiment, a laser processing apparatus, which is an example of the use of the laser apparatus, will be described. Figure 1 is a schematic diagram showing the configuration of the laser processing apparatus. The laser processing apparatus 1000 includes a laser device 100, an optical system 10, a stage 20, and a control device 30.
[0024] The laser device 100 amplifies the laser light output from the light source and outputs the amplified laser light Ln to the optical system 10. The optical system 10 focuses the laser light Ln onto the workpiece 40 placed on the stage 20. In this example, the optical system 10 includes a mirror 11 that bends the optical path of the laser light Ln output from the laser device 100, and an objective lens that focuses the laser light Ln from the mirror 11 onto the workpiece 40. The workpiece 40 is irradiated with the laser light Ln to perform desired processing such as cutting or material modification. The stage 20 is drivable along the X, Y, and Z axes. This allows the laser light Ln to be focused onto a desired position on the workpiece 40. The control device 30 controls the output of the laser light L from the laser device 100 by control signal SIG1. The control device 30 also controls the operation of the stage 20 by control signal SIG2.
[0025] Next, a laser device according to Embodiment 1 will be described. Figure 2 is a schematic diagram showing the configuration of the laser device according to Embodiment 1. The laser device 100 includes a laser light source 1, a control unit 2, optical amplifiers AMP1 to AMPn, and photodetectors PD1 to PDn.
[0026] The laser light source 1 outputs laser light L of a predetermined wavelength, known as a seed laser, to a series of optical amplifiers consisting of optical amplifiers AMP1 to AMPn. The laser light source 1 also has a function to shape the waveform of the laser light L. The laser light source 1 may be various light source devices or light source modules that output laser light of a desired wavelength, such as semiconductor laser elements or semiconductor laser modules.
[0027] Optical amplifiers AMP1 to AMPn form a series of optical amplifiers connected in multiple stages (a so-called cascaded connection). As a result, the laser light L input to the first-stage optical amplifier AMP1 is amplified each time it passes through optical amplifiers AMP1 to AMPn. The laser light Ln amplified by optical amplifiers AMP1 to AMPn is output from the last-stage optical amplifier AMPn. Hereafter, among optical amplifiers AMP1 to AMPn, the optical amplifier placed on the input side of the laser light L for a particular optical amplifier will be referred to as the preceding optical amplifier. The optical amplifier placed on the output side of the laser light Ln for a particular optical amplifier will be referred to as the succeeding optical amplifier.
[0028] In the following, we will distinguish and explain each of the laser beams output after amplification by optical amplifiers AMP1 to AMPn. Therefore, the laser beams output after amplification by optical amplifiers AMP1 to AMPn will be referred to as laser beams L1 to Ln, respectively. However, when there is no need to distinguish between laser beams L1 to Ln, they will simply be referred to as laser beams.
[0029] A portion of the laser light L1 to Ln, amplified by the optical amplifiers AMP1 to AMPn, is branched and incident on the photodetectors PD1 to PDn via the optical transmission lines P1 to Pn. The photodetectors PD1 to PDn detect the incident laser light L1 to Ln. The photodetectors PD1 to PDn then output detection signals DET1 to DETn, indicating the detection result for each of the laser light L1 to Ln, to the control unit 2.
[0030] The photodetectors PD1 to PDn may include, for example, photodiodes. In this case, the current signals indicating the detection results of the laser light L1 to Ln by the photodetectors PD1 to PDn may be output as detection signals DET1 to DETn. Alternatively, the voltage signals obtained by converting the current signals indicating the detection results of the laser light L1 to Ln by the photodetectors PD1 to PDn using a current-to-voltage conversion means such as a transimpedance amplifier may be output as detection signals DET1 to DETn. The photodetectors PD1 to PDn are collectively referred to as the photodetection means.
[0031] The control unit 2 detects the waveforms of the laser beams L1 to Ln, which are amplified by the optical amplifiers AMP1 to AMPn, according to the detection signals DET1 to DETn. The control unit 2 controls the waveform of the laser beam L output by the laser light source 1 using the control signal CON so that the waveforms of the laser beams L1 to Ln become the desired waveforms. In other words, the laser light source 1 pre-distorts the laser beam L so that the waveforms of the laser beams L1 to Ln become the desired waveforms, according to the control signal CON from the control unit 2.
[0032] The control unit 2 may be composed of hardware resources such as a microcomputer (not shown), which includes a processing unit, a storage unit, and an input receiving unit. The processing unit may be composed of a computer including a processor, memory, storage, and communication devices. The processing unit may implement waveform control in the laser device 100 by executing software such as a program read from memory using the processor. The processing unit may also control the reading of data from the storage unit, writing of data to the storage unit, and communication by the communication device. The storage unit may be various storage means capable of storing various types of data, such as memory and hard disks. The input receiving unit may be various interfaces capable of receiving various types of information.
[0033] Next, the waveform control operation in the laser device 100 will be described. Figure 3 is a flowchart showing the waveform control operation in the laser device according to Embodiment 1. Note that before the start of the optical amplifier control operation, the optical amplifiers AMP1 to AMPn are in the OFF state.
[0034] Step S10 The control unit 2 sets the label number k, which specifies the optical amplifier AMP1 to AMPn that is the target of waveform observation of the output laser light, to "1".
[0035] Step S11 The control unit 2 sets the waveform of the laser light L output from the laser light source 1. In the initial state, the control unit 2 sets the initial waveform that it has previously held as the waveform of the laser light L. In states other than the initial state, the control unit 2 sets the waveform updated by subsequent processing as the waveform of the laser light L.
[0036] Step S12 The control unit 2 instructs the laser light source 1 to output laser light L using the control signal CON. As a result, the laser light source 1 outputs laser light L with the set waveform to the optical amplifier AMP1. At this time, the laser light source 1 outputs laser light L having the set pulsed waveform to the optical amplifier AMP1.
[0037] Step S13 The control unit 2 turns on the optical amplifier AMPk.
[0038] Step S14: Photodetectors PD1 to PDn detect laser light L1 to Lk and output detection signals DET1 to DETk indicating the detection result.
[0039] Step S15 The control unit 2 separates and acquires the waveform of the laser light Lk according to the detected signal DETk.
[0040] Step S16 The control unit 2 compares the waveform of the laser light Lk with a desired waveform and determines whether the difference in the waveforms is within a standard range.
[0041] Step S17: If the difference between the waveform of the laser light Lk and the desired waveform is not within the reference range, the control unit 2 turns off the optical amplifier AMPk.
[0042] Generally, when there is no input of amplified laser light when the amplification degree of an optical amplifier is large, the light generated by parasitic oscillation may be amplified by optical amplifier AMPk and enter the subsequent optical amplifier AMPk+1. When such unexpected amplified light enters the subsequent optical amplifier AMPk+1, there is a risk that the subsequent optical amplifier AMPk+1 may fail. Therefore, by turning off the optical amplifier AMPk in step S17, unexpected entry of amplified light into the subsequent optical amplifier AMPk+1 is prevented when there is temporarily no laser input during setting of a laser waveform. However, when the amplification degree of the optical amplifier is small enough that the influence of light generated by parasitic oscillation can be ignored, it is not necessarily required to turn off the optical amplifier AMPk. Accordingly, step S17 may be omitted depending on the application. Here, after turning off the optical amplifier AMPk to update and set the waveform of laser light, the shorter the time until turning the optical amplifier AMPk on again, the more real-time waveform control can be achieved, which is effective from the viewpoint of application. For example, this time is desirably 1 second or less, and more desirably 1 millisecond or less.
[0043] Step S18 The control unit 2 updates the waveform set in the laser light source 1 to eliminate the difference between waveforms.
[0044] Step S19 The control unit 2 instructs the laser light source 1 to stop output of laser light L by a control signal CON. Thereafter, the control unit 2 advances the process to step S11.
[0045] Step S20 When the difference between the waveform of laser light Lk and a desired waveform is within a reference, the control unit 2 determines whether a label number k has reached n. When the label number k is n, the control unit 2 ends the process.
[0046] Step S21 When the label number k is smaller than n, the control unit 2 adds 1 to the label number k and advances the process to step S13.
[0047] By controlling the waveform of the laser beam L output from the laser light source 1 through the above steps S10 to S21, the waveform of the laser beam Ln output from the laser device 100 and amplified by the final-stage optical amplifier AMPn can be adjusted to a desired waveform.
[0048] Next, an example of waveform control of laser light in the laser device 100 will be described. In this example, the desired waveform of the laser beam Ln output from the laser device 100 is a rectangular pulse. In the initial state, the waveform of the laser beam L output from the laser device 100 is set to the same rectangular pulse as the desired waveform. In addition, in the drawings according to the following examples, the pulse waveform of the laser beam is shown with the horizontal direction as the time axis and the vertical direction as the light intensity.
[0049] Initial Stage Fig. 4 is a diagram showing the waveform of laser light in the initial stage. In the initial stage, the waveform of the laser beam L output from the laser device 100 to the foremost-stage optical amplifier AMP1 is a rectangular pulse. In contrast, while the intensity of the laser beam increases each time it is amplified by the optical amplifiers AMP1 to AMPn, the waveform is distorted, and the waveform of the amplified laser beam becomes a pulse waveform falling toward the trailing edge. Further, as amplification is repeated, the intensity decrease in the slope portion of the pulse waveform becomes greater.
[0050] Note that, in the laser device according to the present embodiment and the following embodiments, a part of each of the laser beams L1 to Ln amplified by the optical amplifiers AMP1 to AMPn is branched from an optical transmission line P connecting the optical amplifiers AMP1 to AMPn in multiple stages, to optical transmission lines P1 to Pn connected to photodetectors PD1 to PDn by optical branching means such as beam splitters BS1 to BSn, for example, as shown in Fig. 4.
[0051] When displaying pulse waveforms of laser light in Fig. 4 and the following drawings, the displayed pulse waveforms are merely examples, and the actual pulse waveforms may be any arbitrary waveforms. Therefore, the desired waveform is not limited to a rectangular pulse, and may be any arbitrary waveform. In addition, the shape of the pulse waveform distorted by amplification by an optical amplifier may also be any arbitrary waveform.
[0052] From the initial state described above, the waveform of the laser light L output from the laser light source 1 is controlled so that the waveform of the laser light L1 amplified by the optical amplifier AMP1 corresponding to k=1 in Figure 3 becomes the desired waveform. Figure 5 shows the waveform of the laser light after waveform control based on the laser light amplified by the first stage optical amplifier. By controlling the waveform of the laser light L output from the laser light source 1 to become an upward-sloping pulse waveform, the waveform of the laser light L1 amplified by the optical amplifier AMP1 becomes a rectangular pulse. In contrast, the waveforms of the laser light L2 to Ln amplified by optical amplifiers AMP2 to AMPn are still downward-sloping pulse waveforms, but the slope of the inclined portion becomes gentler.
[0053] Next, the waveform of the laser light L output from the laser light source 1 is controlled so that the waveform of the laser light L2 amplified by the optical amplifier AMP2 corresponding to k=2 in Figure 3 becomes the desired waveform. Figure 6 shows the waveform of the laser light after waveform control based on the laser light amplified by the second stage optical amplifier. By controlling the waveform of the laser light L output from the laser light source 1 to become a steeper, upward-sloping pulse waveform, the waveform of the laser light L2 amplified by the optical amplifier AMP2 becomes a rectangular pulse. As the slope of the pulse waveform of the laser light L becomes steeper, the waveform of the laser light L1 becomes an upward-sloping pulse waveform. The waveform of the laser light amplified by the later optical amplifier is still a downward-sloping pulse waveform, but the slope of the inclined portion becomes even gentler.
[0054] Subsequently, as the process in Figure 3 progresses, the waveform of the laser light L output from the laser light source 1 is controlled so that the waveform of the laser light Ln amplified by the last-stage optical amplifier AMPn corresponding to k=n becomes the desired waveform. Figure 7 shows the waveform of the laser light after waveform control based on the laser light amplified by the last-stage optical amplifier. By controlling the waveform of the laser light L output from the laser light source 1 to become an even steeper, upward-sloping pulse waveform, the waveform of the laser light Ln amplified by the optical amplifier AMPn can be made into a rectangular pulse. As the slope of the pulse waveform of the laser light L becomes even steeper, the waveform of the laser light output from the optical amplifier preceding the optical amplifier AMPn becomes an upward-sloping pulse waveform.
[0055] As explained above, the waveform can be sequentially shaped into a desired waveform, starting from the laser light L1 amplified by the first-stage optical amplifier AMP1 and continuing to the laser light Ln amplified by the last-stage optical amplifier AMPn.
[0056] Generally, when controlling the waveform of laser light L by observing only the waveform of laser light Ln, it is unclear to what extent the distortion of the laser light caused by the amplification of each optical amplifier AMP1 to AMPn contributes to the distortion of laser light Ln. Therefore, in this case, it is difficult to control the waveform of laser light L so that the waveform of laser light Ln becomes the desired waveform. In contrast, in the laser device 100, pre-distortion is applied to the laser light L in order from the preceding optical amplifier to eliminate the distortion caused by amplification. Therefore, since the distortion of the laser light waveform caused by amplification in the preceding optical amplifier has already been corrected, the distortion of the laser light waveform output from the optical amplifier one stage later can be minimized. As a result, the distortion caused by amplification in each optical amplifier can be easily corrected by applying pre-distortion to the waveform of laser light L.
[0057] As a result, the laser device 100 can quickly and efficiently shape the waveform of the output laser light Ln into a desired waveform.
[0058] In the above description, the waveform of the laser light L output from the laser light source 1 was explained as being controlled so that the waveforms amplified by each of the optical amplifiers AMP1 to AMPn sequentially become the desired waveform. However, if the laser light Ln output from the laser device can be shaped into the desired waveform, it is not necessary to sequentially shape the waveforms of all n-1 optical amplifiers preceding optical amplifier AMPn into the desired waveform. In other words, if the laser light Ln output from optical amplifier AMPn can be shaped into the desired waveform, the waveform of the laser light L output from the laser light source 1 may be controlled so that only some of the waveforms of the n-1 optical amplifiers preceding optical amplifier AMPn sequentially become the desired waveform.
[0059] Figure 8 is a flowchart showing a modified example of the waveform control operation in the laser device according to Embodiment 1. In Figure 8, steps S101 and S102 are inserted between steps S13 and S14.
[0060] In this example, the control unit 2 is pre-assigned label numbers to indicate the optical amplifiers among the optical amplifiers AMP1 to AMPn-1 that are to be skipped because they do not perform the operation of controlling the laser light source 1 based on the amplified waveform. Note that the waveform control operation in Figure 8 is performed to shape the laser light Ln output from optical amplifier AMPn into a desired waveform, so "n" is not specified as the label number indicating the optical amplifier to be skipped.
[0061] Steps S10 to S13 in Figure 8 are the same as in Figure 3, so redundant explanations are omitted.
[0062] In step S101, the control unit 2 determines whether the label number k indicating the optical amplifier used for waveform control is a number to be skipped. If the label number k indicating the optical amplifier used for waveform control is not a number to be skipped, the control unit 2 proceeds to step S14.
[0063] Step S102 If the label number k indicating the optical amplifier used for waveform control is a number to be skipped, the control unit 2 adds "1" to the label number k and proceeds to step S13.
[0064] Steps S13 to S21 in Figure 8 are the same as in Figure 3, so redundant explanations are omitted.
[0065] According to the procedure shown in Figure 8, the laser light Ln output from the optical amplifier AMPn can be shaped into a desired waveform with fewer processing steps. Therefore, the laser light can be shaped into a desired waveform while reducing the time required for controlling the laser light waveform.
[0066] Embodiment 2 In the laser device 100 according to Embodiment 1, laser light L1 to Ln amplified by optical amplifiers AMP1 to AMPn is incident on photodetectors PD1 to PDn. However, when the laser device is mounted on a laser processing device, the intensity of the amplified laser light L1 to Ln is relatively large (for example, 10 ６ It is assumed that the amplification factor will be approximately [a certain degree]. Therefore, if high-intensity laser light L1 to Ln is incident directly on the photodetectors PD1 to PDn, it may become impossible for the photodetectors PD1 to PDn to accurately detect the intensity of the laser light L1 to Ln. Furthermore, depending on the intensity of the incident laser light L1 to Ln, the photodetectors PD1 to PDn may malfunction. Therefore, in this embodiment, a laser device in which the intensity of the laser light L1 to Ln incident on the photodetectors PD1 to PDn can be adjusted will be described.
[0067] Figure 9 is a schematic diagram showing the configuration of the laser device according to Embodiment 2. The laser device 200 has a configuration in which optical attenuators ATT1 to ATTn are added to the laser device 100 according to Embodiment 1.
[0068] Optical attenuators ATT1 to ATTn are inserted between optical amplifiers AMP1 to AMPn and photodetectors PD1 to PDn, respectively. Optical attenuators ATT1 to ATTn attenuate the laser light L1 to Ln incident from optical amplifiers AMP1 to AMPn by a predetermined amount. Optical attenuators ATT1 to ATTn output the attenuated laser light L1 to Ln to photodetectors PD1 to PDn, respectively.
[0069] The laser light L1 to Ln, amplified by optical amplifiers AMP1 to AMPn, becomes more intense the further it is amplified by the subsequent optical amplifiers. Therefore, it is preferable that the attenuation of the laser light L1 to Ln in optical attenuators ATT1 to ATTn increases in order. That is, it is preferable that the attenuation of optical attenuator ATT1 is at its minimum value, the attenuation of optical attenuator ATTn is at its maximum value, and the attenuation increases monotonically from optical attenuator ATT1 to optical attenuator ATTn.
[0070] According to the laser device 200, the intensity of the laser light L1 to Ln incident on each of the photodetectors PD1 to PDn can be adjusted to an intensity that allows the photodetectors PD1 to PDn to suitably detect the laser light L1 to Ln. As a result, the control unit 2 can more easily and accurately acquire the waveform of the laser light Lk from the optical amplifier AMPk, which is the waveform of the laser light L1 to Ln that is to be observed.
[0071] Embodiment 3 In Embodiments 1 and 2, a laser device was described in which the same number of photodetectors PD1 to PDn were provided corresponding to the optical amplifiers AMP1 to AMPn. On the other hand, when considering the integration of the laser device into a laser processing device, it is preferable that the laser device be small. Therefore, in this embodiment, a laser device that can be miniaturized will be described.
[0072] Figure 10 is a schematic diagram showing the configuration of the laser device according to Embodiment 3. The laser device 300 has a configuration in which an optical multiplexer 3 is added to the laser device 200 according to Embodiment 2, and the photodetectors PD1 to PDn of the laser device 200 are replaced with a single photodetector PD. The photodetector PD is also referred to as an optical detection means.
[0073] Laser light L1 to Ln, which has been attenuated by optical attenuators ATT1 to ATTn, is incident on the optical multiplexer 3. The optical multiplexer 3 couples the incident laser light L1 to Ln into a single optical transmission path P0 connected to the photodetector PD.
[0074] Therefore, laser light L1 to Ln is incident on the photodetector PD via a single optical transmission path P0. On the other hand, by designing the optical path lengths P1 to Pn from each of the optical amplifiers AMP1 to AMPn to the photodetector PD to increase in order, the incidence timing of the laser light L1 to Ln to the photodetector PD can be discrete so that the pulse waveforms do not overlap.
[0075] Specifically, when j is an integer greater than or equal to 1, the lengths of the optical transmission paths P1 to Pn should be set such that the delay amount of the laser light Lj+1 incident on the optical transmission path Pj+1, which is amplified by AMPj+1 and then has an optical attenuator ATTj inserted, is greater than the width of the laser light pulse waveform, relative to the laser light Lj incident on the optical transmission path Pj+1, which is amplified by AMPj+1 and then has an optical attenuator ATTj inserted.
[0076] Figure 10 shows an example where the pulse waveforms of the laser light L1 to Ln entering the photodetector PD are aligned at intervals of Δt so that they do not overlap. Note that the pulse waveforms shown in Figure 10 are displayed to explain the timing of the pulse waveforms entering the photodetector PD, and the displayed pulse waveforms are merely illustrative.
[0077] As a result, the control unit 2 can identify multiple pulse waveforms incident on the photodetector PD, which are included in the waveform acquired based on the detection signal DET, and selectively acquire the pulse waveform to be observed.
[0078] Next, the control operation of the optical amplifier in the laser device 300 will be described. Figure 11 is a flowchart showing the waveform control operation in the laser device according to Embodiment 3. In Figure 11, steps S14 and S15 in Figure 3 are replaced by steps S24 and S25, respectively.
[0079] Steps S10 to S13 in Figure 11 are the same as in Figure 3, so redundant explanations are omitted.
[0080] Step S24 The photodetector PD outputs a detection signal DET indicating the detection result of the laser light L1 to Lk.
[0081] Step S25 The control unit 2 acquires the waveforms of the laser light L1 to Lk according to the detection signal DET. As described above, in the laser device 300, the incidence timing of the laser light L1 to Ln to the photodetector PD is discrete so that the pulse waveforms do not overlap. As a result, the control unit 2 selectively acquires the waveform of the laser light Lk based on the order of the pulses that appear in the waveforms of the laser light L1 to Lk.
[0082] Steps S16 to S21 in Figure 11 are the same as in Figure 3, so redundant explanations are omitted.
[0083] As described above, the laser device 300 can selectively acquire the waveform of the laser light Lk from the optical amplifier AMPk that is to be observed, which is included in the waveform acquired based on the detection signal DET indicating the detection results of the laser light L1 to Lk. As a result, the laser device 300 can control the waveform of the laser light Ln output by the laser light source 1 to a desired waveform, similar to the laser devices according to Embodiments 1 and 2.
[0084] Furthermore, with this configuration, the control unit 2 can detect a waveform consisting of a series of pulse waveforms of laser light amplified by multiple optical amplifiers, based on the detection signal DET. Therefore, for example, during waveform control operation, or during operation of the laser device after waveform control, fluctuations in the amplification operation of each optical amplifier can be detected by monitoring the waveform consisting of a series of pulse waveforms of laser light amplified by multiple optical amplifiers based on the detection signal DET. Thus, with this configuration, it is also possible to easily detect the occurrence of abnormalities in each optical amplifier.
[0085] Embodiment 4 In Embodiment 3, it was described that the laser light L amplified by the optical amplifiers AMP1 to AMPn is input to the photodetector PD via optical attenuators ATT1 to ATTn, respectively. In this case, it is required to discretely set the incidence timing of the laser light L1 to Ln to the photodetector PD so that the pulse waveforms do not overlap. Therefore, in this embodiment, a laser device is described in which the incidence timing of the laser light L1 to Ln to the photodetector PD can be set to a desired timing.
[0086] Figure 12 is a schematic diagram showing the configuration of the laser device according to Embodiment 4. The laser device 400 is the same as the laser device 300 according to Embodiment 3, with optical delayers D1 to Dn added. The optical delayers D1 to Dn are inserted between the optical attenuators ATT1 to ATTn and the optical multiplexer 3, respectively.
[0087] Optical delayers D1 to Dn delay the laser light L1 to Ln, which is incident from optical amplifiers AMP1 to AMPn via optical attenuators ATT1 to ATTn, by a predetermined delay amount, and then output it to the optical multiplexer 3. Optical delayers D1 to Dn may be composed of delay lines such as optical fibers.
[0088] In order for the control unit 2 to reliably separate the waveforms of the laser beams L1 to Ln, it is preferable that the delay amounts of the optical delayers D1 to Dn increase in order. That is, it is preferable that the delay amount of optical delayer D1 is the minimum value, the delay amount of optical delayer Dn is the maximum value, and the delay amount increases monotonically from optical delayer D1 to optical delayer Dn.
[0089] According to the laser device 400, the timing of when the laser beams L1 to Ln are incident on the photodetector PD can be reliably discrete using the optical delayers D1 to Dn. Specifically, when j is an integer of 1 or more, the lengths of the optical transmission paths P1 to Pn and the delay amounts in the optical delayers D1 to Dn should be set such that the delay amount of the laser beam Lj+1 incident on the optical multiplexer 3 via the optical transmission path Pj+1 (amplified by AMPj and then having an optical attenuator ATTj+1 inserted) and the optical delayer Dj+1 is greater than the width of the laser beam pulse waveform, relative to the laser beam Lj incident on the optical multiplexer 3 via the optical transmission path Pj+1 (amplified by AMPj and then having an optical attenuator ATTj inserted) and the optical delayer Dj. As a result, the control unit 2 can more easily acquire the waveform of the laser beam Lk from the optical amplifier AMPk to be observed, which is included in the waveform acquired based on the detection signal DET.
[0090] Embodiment 5 In Embodiments 1 to 4, the case where the gains of the optical amplifiers AMP1 to AMPn are constant was described, but the gains of the optical amplifiers AMP1 to AMPn may be variable. However, when the gains of the optical amplifiers AMP1 to AMPn are variable, the waveform of the laser light amplified by the optical amplifier may change depending on the gain.
[0091] For example, when amplifying light using an optical amplifier, instead of setting the gain of the optical amplifier to 100% from the beginning, an adjustment method is used in which the gain is gradually increased until it finally reaches 100%. In this case, changing the gain of the optical amplifier may change the waveform of the light amplified by the optical amplifier. Therefore, when changing the gain, it is necessary to observe the waveform of the light amplified by the optical amplifier each time and adjust the pre-distortion applied to the laser light output from the laser light source.
[0092] Therefore, this embodiment describes a laser device capable of adjusting the waveform of laser light in accordance with changes in the gain of the optical amplifier.
[0093] Figure 13 is a schematic diagram showing the configuration of the laser device according to Embodiment 5. The laser device 500 has a configuration in which the gains of the optical amplifiers AMP1 to AMPn are variable, compared to the laser device 100 according to Embodiment 1. In the laser device 500, the gains of the optical amplifiers AMP1 to AMPn can be adjusted by providing control signals CON1 to CONn from the control unit 2 to the optical amplifiers AMP1 to AMPn.
[0094] Next, the waveform control of the laser light in the laser device 500 will be described. Figure 14 is a flowchart showing the waveform control operation in the laser device according to Embodiment 5. In Figure 14, step S51 is inserted between step S13 and step S14. Also in Figure 14, steps S52 and S53 are inserted between step S16 and step S20.
[0095] Steps S10 to S13 in Figure 14 are the same as in Figure 3, so redundant explanations are omitted.
[0096] Step S51 The control unit 2 sets the gain of the optical amplifier AMPk. In the initial state, the control unit 2 sets the initial gain, which was previously held, as the gain of the optical amplifier AMPk. At this time, it is preferable that the gain of the optical amplifier AMPk be a low value, such as 10% or 20%. In states other than the initial state, the control unit 2 sets the gain updated by subsequent processing as the gain of the optical amplifier AMPk.
[0097] Steps S14 to S19 in Figure 14 are the same as in Figure 3, so redundant explanations are omitted.
[0098] Step S52 The control unit 2 determines whether the gain set in the optical amplifier AMPk is the desired gain. The desired gain may be, for example, 100%. If the gain set in the optical amplifier AMPk is the desired gain, the control unit 2 proceeds to step S20.
[0099] Step S53 If the gain set for the optical amplifier AMPk is not the desired gain, the control unit 2 updates the gain set for the optical amplifier AMPk to approach the desired gain. For example, if the desired gain is 100% and the gain set for the optical amplifier AMPk is 50%, the control unit 2 may increase the gain set for the optical amplifier AMPk by a predetermined increment, such as +10%, to approach 100%. After that, the control unit 2 proceeds to step S51. As a result, in step S51, the updated new gain is set for the optical amplifier AMPk.
[0100] Step S20 in Figure 14 is the same as in Figure 3, except that it is performed when the gain set for the optical amplifier AMPk in step S52 is the desired gain, so a redundant explanation is omitted.
[0101] Step S21 in Figure 14 is the same as in Figure 3, so the redundant explanation is omitted.
[0102] As explained above, in the laser device 500, the waveform control of the laser light L can be repeatedly performed until the gain of the optical amplifier AMPk reaches a desired gain, such as 100%. This allows the gain of each optical amplifier to be set to the desired gain, and a laser light Ln with a desired waveform can be output from the laser device 500.
[0103] Other Embodiments Although the present disclosure has been described above with reference to embodiments, the present disclosure is not limited to the embodiments described above. Various modifications to the structure and details of the present disclosure are possible, which can be understood by those skilled in the art within the scope of the present disclosure. Furthermore, each embodiment can be combined with other embodiments as appropriate.
[0104] In the laser devices 300 and 400 according to Embodiments 3 and 4, if the laser light L1 to Ln can be suitably detected by the photodetector PD, the configuration may be the same as the laser device 100 according to Embodiment 1, without optical attenuators ATT1 to ATTn.
[0105] In the laser device 500 according to Embodiment 5, similar to the laser device 200 according to Embodiment 2, optical attenuators ATT1 to ATTn may be provided between the optical amplifiers AMP1 to AMPn and the photodetectors PD1 to PDn, respectively. Also, in the laser device 500 according to Embodiment 5, similar to the laser device 400 according to Embodiment 4, optical delayers D1 to Dn may be provided between the optical attenuators ATT1 to ATTn and the photodetectors PD1 to PDn, respectively. Furthermore, in the laser device 500 according to Embodiment 5, similar to the laser devices 300 and 400 according to Embodiments 3 and 4, an optical multiplexer 3 and a photodetector PD may be provided instead of photodetectors PD1 to PDn.
[0106] In the laser device 200 according to Embodiment 2, similar to the laser device 400 according to Embodiment 4, optical delayers D1 to Dn may be provided between the optical attenuators ATT1 to ATTn and the photodetectors PD1 to PDn, respectively.
[0107] The arrangement of optical attenuators ATT1 to ATTn and the arrangement of optical delayers D1 to Dn may be swapped.
[0108] In the laser devices 100, 200, and 500 according to Embodiments 1, 2, and 5, the incidence timing of the laser light L1 to Ln to the photodetectors PD1 to PDn may be discrete, similar to the laser devices 300 and 400 according to Embodiments 3 and 4. This allows the control unit 2 to monitor the pulse waveform of the laser light amplified by the multiple optical amplifiers based on the detection signals DET1 to DETn, for example, during waveform control operation or during operation of the laser device after waveform control, and to detect fluctuations in the amplification operation of each optical amplifier. This also makes it possible to easily detect the occurrence of abnormalities in each optical amplifier.
[0109] In Figure 1, the control device 30 of the laser processing apparatus 1000 and the control unit 2 of the laser apparatus 100 are explained separately, but this is merely an example. The control unit 2 of the laser apparatus 100 may be incorporated into the control device 30 as part of the control device 30 of the laser processing apparatus 1000.
[0110] Although a laser processing apparatus 1000 has been described as an example of the use of the laser device 100, the laser device 100 may be mounted on any device of the laser processing apparatus. In this case, the control unit 2 of the laser device 100 may be incorporated into the control unit of any device on which the laser device 100 is mounted.
[0111] Each drawing is merely illustrative to illustrate one or more embodiments. Each drawing may be associated with one or more other embodiments, rather than being associated with only one specific embodiment. As those skilled in the art will understand, various features or steps described with reference to any one drawing can be combined with features or steps shown in one or more other drawings, for example, to create embodiments not explicitly shown or described. Not all features or steps shown in any one drawing to illustrate an exemplary embodiment are necessarily required, and some features or steps may be omitted. The order of steps described in any of the drawings may be changed as appropriate.
[0112] Some or all of the above embodiments may also be described as follows, but are not limited to the following:
[0113] This application claims priority based on Japanese Patent Application No. 2025-51773, filed on 26 March 2025, and incorporates all of its disclosures herein.
[0114] 1 Laser light source 2 Control unit 3 Optical multiplexer 10 Optical system 20 Stage 30 Control device 40 Workpiece 100, 200, 300, 400, 500 Laser device 1000 Laser processing device AMP1 to AMPn Optical amplifier ATT1 to ATTn Optical attenuator BS1 to BSn Beam splitter CON, CON1 to CON2 Control signal D1 to Dn Optical delay unit DET, DET1 to DETk Detection signal L, L1 to Ln Laser light P, P0 to Pn Optical transmission line PD, PD1 to PDn Photodetector
Claims
1. A laser device comprising: a laser light source that outputs laser light; a plurality of optical amplifiers connected in series in multiple stages that stepwise amplify the laser light output from the laser light source; an optical detection means that detects the laser light amplified by the plurality of optical amplifiers and outputs a detection signal indicating the detection result; and a control unit that sequentially acquires a part or all of the waveform of the laser light amplified by the plurality of optical amplifiers based on the detection signal, from the front stage to the back stage of the multi-stage connection, and controls the waveform of the laser light output from the laser light source so that each of the sequentially acquired waveforms becomes a desired waveform, thereby shaping the waveform of the laser light amplified by the last stage optical amplifier to become the desired waveform.
2. The laser apparatus according to claim 1, wherein the control unit sequentially acquires the waveform of the laser light amplified by the last stage optical amplifier and any number of optical amplifiers between the first stage optical amplifier and the optical amplifier immediately preceding the last stage optical amplifier among the plurality of optical amplifiers, from the front to the back of the multi-stage connection.
3. The laser apparatus according to claim 1 or 2, comprising: a plurality of optical transmission paths for transmitting laser light amplified by the plurality of optical amplifiers to the optical detection means, and a plurality of optical attenuators inserted in each of the plurality of optical transmission paths.
4. The laser apparatus according to claim 3, wherein the optical attenuator has a greater attenuation amount when laser light amplified by the subsequent optical amplifier is incident on it.
5. A laser apparatus according to any one of claims 1 to 4, comprising a plurality of optical transmission paths for transmitting laser light amplified by the plurality of optical amplifiers, wherein the optical detection means includes a plurality of photodetectors that detect laser light amplified by the plurality of optical amplifiers incident through the plurality of optical transmission paths and output a plurality of signals indicating the detection result as the detection signals, and the control unit acquires a part or all of the waveform of the laser light amplified by the plurality of optical amplifiers sequentially from the preceding stage to the succeeding stage of the multi-stage connection based on the plurality of signals.
6. A laser apparatus according to any one of claims 1 to 4, comprising: a plurality of optical transmission lines for each transmitting laser light amplified by the plurality of optical amplifiers; an optical multiplexer into which the laser light amplified by the plurality of optical amplifiers is incident, the incident laser light is combined and output to the optical detection means, the optical detection means outputs the detection result of the laser light combined by the optical multiplexer as the detection signal; the laser light amplified by the plurality of optical amplifiers is incident on the optical detection means in a temporally discrete manner so that their waveforms do not overlap; and the control unit acquires a part or all of the waveforms of the laser light amplified by the plurality of optical amplifiers sequentially from the preceding stage to the succeeding stage of the multi-stage connection, based on the discrete and continuous waveforms corresponding to the laser light detected by the optical detection means, which are acquired based on the detection signal.
7. In the multi-stage connection, the delay amount of the laser light incident on the optical multiplexer via the optical transmission path connected to the later optical amplifier among the two adjacent optical amplifiers is greater than the width of the pulse waveform of the laser light, with respect to the laser light incident on the optical multiplexer via the optical transmission path connected to the earlier optical amplifier among the two adjacent optical amplifiers. The laser apparatus according to claim 6.
8. The laser apparatus according to claim 6, comprising a plurality of optical delayers inserted in each of the plurality of optical transmission paths.
9. In the multi-stage connection, the delay amount of the laser light incident on the optical multiplexer via the optical transmission path and optical delay device connected to the later optical amplifier among the two adjacent optical amplifiers is greater than the width of the pulse waveform of the laser light, with respect to the laser light incident on the optical multiplexer via the optical transmission path and optical delay device connected to the earlier optical amplifier among the two adjacent optical amplifiers. The laser apparatus according to claim 8.
10. The laser apparatus according to any one of claims 1 to 9, wherein each of the plurality of optical amplifiers has a variable gain.
11. The laser apparatus according to claim 10, wherein the control unit changes the gain of the optical amplifier whose waveform of amplified laser light is to be observed among the plurality of optical amplifiers toward a desired gain, and each time the gain is changed, the control unit shapes the waveform of the laser light amplified by the optical amplifier whose waveform is to be observed toward the desired waveform.
12. A laser processing apparatus comprising: the laser apparatus according to any one of claims 1 to 11; a driveable stage for holding a workpiece; an optical system for focusing laser light output from the laser apparatus onto the workpiece held on the stage; and a control device for controlling the output of the laser light from the laser apparatus and the driving of the stage.
13. A waveform control method comprising: outputting laser light to a plurality of optical amplifiers connected in series in multiple stages; amplifying the input laser light in stages by the plurality of optical amplifiers; detecting each of the laser light amplified by the plurality of optical amplifiers and outputting a detection signal indicating the detection result; acquiring part or all of the waveforms of the laser light amplified by the plurality of optical amplifiers sequentially from the front to the back of the multi-stage connection based on the detection signal; and controlling the waveforms of the laser light input to the plurality of optical amplifiers so that each of the sequentially acquired waveforms becomes a desired waveform, thereby shaping the waveform of the laser light amplified by the last optical amplifier to become the desired waveform.