JP6154364B2 - Fiber laser equipment - Google Patents

Description

  The present invention relates to a fiber laser device that can perform processing with light having a substantially rectangular pulse time waveform even when the pulse width is long.

  A fiber laser device that amplifies and emits seed light using an optical fiber for amplification is used as one of laser devices used for processing machines that perform processing using laser light and medical devices such as scalpels that use laser light. It has been. Some fiber laser devices emit pulsed light having a small duty ratio (ratio of the width of the pulsed light to the pulse period).

  The pulse time waveform of light emitted from such a fiber laser device, that is, the temporal change in the power of light per pulse, the wavelength, and the like are the properties of the workpiece such as the material and thickness of the workpiece, It is determined by a processing method such as how to process the workpiece. For example, a fiber laser device that emits light having a substantially rectangular pulse time waveform, that is, light having a shape in which the power of the light steeply rises and the light power sharply falls while maintaining a constant light power for a predetermined time. May be required.

  The reason why a fiber laser device that emits light having a pulse time waveform close to a rectangle is required is as follows. That is, when light having a higher power than necessary is irradiated onto the workpiece, plasma may be generated from the workpiece, and the generated plasma may absorb the light, preventing desired processing. On the other hand, when light of low power is irradiated on the workpiece, the workpiece cannot be ablated, and unnecessary heat generation occurs, which may cause unintended thermal distortion in the workpiece. For this reason, depending on the material of the workpiece and the processing method, there is a demand for processing using light having a substantially rectangular pulse time waveform, and the above-described fiber laser device is required.

  Patent Document 1 listed below describes a fiber laser device that attempts to emit light having such a pulse time waveform that is substantially rectangular. The fiber laser device of Patent Document 1 is a MO-PA (Master Oscillator-Power Amplifier) type fiber laser device, and a seed light source (MO) emits seed light having a substantially rectangular pulse time waveform. Specifically, the time waveform of this seed light has a steep rise time with a rise time of about 1 nsec, a constant power is maintained for a predetermined time of about 5 nsec, and the fall time is about 2 nsec. Has a steep fall time. According to Patent Document 1, the fiber laser device can emit substantially rectangular light when the seed light is amplified by a fiber amplifier (PA) and emitted. At that time, part of the amplified light is Raman shifted.

Special table 2003-536266 gazette

  However, the amplification factor of light within one pulse in the fiber amplifier is not constant. Specifically, the light component on the rising side of the pulse tends to be amplified with a high amplification factor, and the amplification factor tends to decrease as it proceeds toward the falling side of the pulse. Therefore, the shape of the pulse time waveform of the light emitted from the fiber amplifier is easily deformed from the shape of the pulse time waveform of the seed light input to the fiber amplifier, and from the seed light source as in the fiber laser device described in Patent Document 1. Even when the pulse time waveform of the emitted light is substantially rectangular, the pulse time waveform of the light emitted from the fiber amplifier is easily deformed from the rectangular shape. In particular, when the pulse width is long, such as 100 ns, that is, when the time per pulse is long, this tendency becomes more remarkable.

  Accordingly, an object of the present invention is to provide a fiber laser device that can perform processing with light having a substantially rectangular pulse time waveform even when the pulse width is long.

  The fiber laser device of the present invention includes a seed light source that emits light of a predetermined wavelength that is pulsed by a Q switch, an amplification optical fiber that amplifies the light of the predetermined wavelength emitted from the seed light source, and the amplification light source A wavelength conversion unit that generates primary scattered light and secondary scattered light emitted from an optical fiber by stimulated Raman scattering, and light emitted from the wavelength conversion unit is incident and transmits the primary scattered light. And an optical filter that suppresses transmission of the light of the predetermined wavelength and the secondary scattered light.

  The pulse time waveform of the light pulsed by the Q switch has a generally Gaussian distribution shape. When the light having such a shape is amplified by the amplification optical fiber, the light can be amplified while maintaining the shape. This property does not change so much even when the pulse width of the amplified light is long. Of the light having the Gaussian distribution shape, a light component having a power density higher than a specific power density in the wavelength conversion unit is shifted in wavelength by stimulated Raman scattering to become primary scattered light. The light component that does not become primary scattered light is light having a low power density including a tail portion in the Gaussian distribution shape, and is kept at a predetermined wavelength. Further, among the primary scattered light, a light component having a power density higher than a specific power density different from the specific power density is wavelength-shifted by stimulated Raman scattering to become secondary scattered light. The light component that becomes the secondary scattered light is light having a high power density, including the apex portion of the Gaussian distribution shape. The pulse time waveform of the primary scattered light has a generally rectangular shape because light having a low power density including the tailing portion and light having a high power density including the apex portion are removed from the light having a Gaussian distribution shape. In the optical filter, transmission of light having a predetermined wavelength that is not wavelength-converted and secondary scattered light is suppressed, and primary scattered light is transmitted. Therefore, this fiber laser device can emit light having a substantially rectangular pulse time waveform even when the pulse width is long. As described above, according to the fiber laser device of the present invention, even when the pulse width is long, processing can be performed with light having a substantially rectangular pulse time waveform.

  Alternatively, the fiber laser device of the present invention includes a seed light source that emits light of a predetermined wavelength that is pulsed by a Q switch, an amplification optical fiber that amplifies the light of the predetermined wavelength emitted from the seed light source, A wavelength conversion unit for generating primary scattered light and secondary scattered light of the predetermined wavelength emitted from the amplification optical fiber by stimulated Raman scattering, light emitted from the wavelength conversion unit is incident, and the primary scattered light and An optical filter that transmits the secondary scattered light and suppresses transmission of the light having the predetermined wavelength, and the light emitted from the filter absorbs the primary scattered light and transmits the secondary scattered light. The workpiece is irradiated with light.

  In this fiber laser device, transmission of low power density light including a tail portion in a Gaussian distribution shape is suppressed by an optical filter. In addition, light having a high power density, which becomes secondary scattered light, is emitted from the fiber laser device but passes through the workpiece. Therefore, this fiber laser device can process the workpiece by the primary scattered light. The pulse time waveform of the primary scattered light is generally rectangular as described above. Therefore, even with this fiber laser device, even when the pulse width is long, processing can be performed with light having a substantially rectangular pulse time waveform.

  In the above fiber laser device, it is preferable that the primary scattered light has a pulse width of 100 nsec or more. Even with light having a long pulse width of 100 nsec or longer, according to the fiber laser device of the present invention, processing can be performed with light having a pulse time waveform that is substantially rectangular. By processing with light having such a long pulse width, a material having a low primary scattered light absorption rate can be processed to a deep position.

  Further, in this case, the pulse width of the primary scattered light may be 500 nsec or less. Light having a pulse width of 500 nsec or less can be easily obtained by Q-switch oscillation.

  As described above, according to the present invention, there is provided a fiber laser device that can perform processing with light having a substantially rectangular pulse time waveform even when the pulse width is long.

1 is a diagram illustrating a fiber laser device according to a first embodiment of the present invention. It is a figure which shows the pulse time waveform and wavelength of the light which propagates the fiber laser apparatus shown in FIG. It is a figure which shows the pulse time waveform and wavelength of the light which propagate the fiber laser apparatus which concerns on 2nd Embodiment of this invention.

  DESCRIPTION OF EMBODIMENTS Hereinafter, preferred embodiments of a fiber laser device according to the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 is a diagram showing a fiber laser device according to a first embodiment of the present invention.

  As shown in FIG. 1, the fiber laser device 1 includes a seed light source 10 that emits seed light, an amplifier unit 20 that amplifies the seed light source, a wavelength conversion unit 30, and an optical filter 40. As described above, the fiber laser device 1 is an MO-PA type fiber laser device in which the seed light source 10 is an MO (Master Oscillator) and the amplifier unit 20 is a PA (Power Amplifier).

  The seed light source 10 includes a continuous light generator 11 that emits continuous light and a Q switch 12 as main components. The continuous light generator 11 includes, for example, a laser diode, a Fabry-Perot type fiber laser device, a solid-state laser device, and the like. The Q switch 12 is composed of, for example, an A / O element (acousto-optic element) that can be controlled from the outside by an electrical signal, and repeats a low loss state and a high loss state of the light from the continuous light generator 11. Be controlled.

  By controlling the Q switch 12 in this way, pulsed seed light is emitted from the seed light source 10. The pulse time shape of the seed light is a Gaussian distribution shape. The wavelength of the seed light is, for example, 1064 nm or 1080 nm. The seed light emitted from the seed light source 10 enters the optical fiber 15 and propagates through the core of the optical fiber 15. The optical fiber 15 is, for example, a single mode fiber. In this case, the seed light propagates through the optical fiber 15 as single mode light.

  The amplifier unit 20 includes an excitation light source 21, an amplification optical fiber 22, and an optical coupler 23 as main components.

  The excitation light source 21 includes a plurality of laser diodes, and emits excitation light having a wavelength for exciting rare earth elements added to the amplification optical fiber 22 described later, for example, excitation light having a wavelength of 915 nm. Further, the pumping light emitted from each laser diode of the pumping light source 21 enters the optical fiber 25 and propagates through the optical fiber 25. An example of the optical fiber 25 is a multimode fiber. In this case, pumping light propagates in the optical fiber 25 as multimode light.

  The amplification optical fiber 22 includes a core, an inner cladding that surrounds the outer peripheral surface of the core without a gap, an outer cladding that covers the outer peripheral surface of the inner cladding, and a coating layer that covers the outer peripheral surface of the outer cladding. It is a fiber. The core is made of quartz to which a rare earth element excited by excitation light emitted from the excitation light source 21 is added. As described above, when the wavelength of the seed light is 1064 nm or 1080 nm, the rare earth added may include ytterbium (Yb). In addition, if the wavelength of the seed light is other wavelength, other rare earth can be used. Besides Yb, thulium (Tm), cerium (Ce), neodymium (Nd), europium (Eu), erbium (Er ) And the like can be added. The refractive index of the inner cladding is lower than the refractive index of the core, and the refractive index of the outer cladding is further lower than the refractive index of the inner cladding. Therefore, in addition to the rare earth element, for example, an element such as germanium that increases the refractive index is added to the core. In this case, the cladding is made of, for example, pure quartz to which no dopant is added. The outer cladding is made of, for example, an ultraviolet curable resin, and the coating layer is made of, for example, an ultraviolet curable resin that is different from the resin constituting the outer cladding.

  The optical coupler 23 connects the optical fiber 15 and each optical fiber 25 to the incident end of the amplification optical fiber 22. Specifically, in the optical coupler 23, the core of the optical fiber 15 is connected to the core of the amplification optical fiber 22, and the core of each optical fiber 25 is connected to the inner cladding of the amplification optical fiber 22. Has been. Accordingly, the seed light emitted from the seed light source 10 enters the core of the amplification optical fiber 22, and the excitation light emitted from the excitation light source 21 enters the inner cladding of the amplification optical fiber 22. In the amplification optical fiber 22, the power of the seed light is amplified as described later, and light having a high power density is emitted.

  Light emitted from the amplification optical fiber 22 enters the wavelength conversion unit 30. The wavelength conversion unit 30 is made of, for example, an optical fiber, and is configured such that stimulated Raman scattering occurs when light amplified by the amplification optical fiber 22 is incident, and primary scattered light and secondary scattered light are generated. Let When the wavelength of the light emitted from the amplification optical fiber 22 is 1064 nm, the wavelength conversion unit generates primary scattered light having a wavelength of 1120 nm and secondary scattered light having a wavelength of 1175 nm. When the wavelength of light emitted from the amplification optical fiber 22 is 1080 nm, the wavelength conversion unit generates primary scattered light having a wavelength of 1135 nm and secondary scattered light having a wavelength of 1190 nm.

  When the wavelength conversion unit 30 is made of an optical fiber and the wavelength is 1064 nm or 1080 nm and light with a power of 4 kW is incident, this optical fiber is, for example, a single mode fiber having a core diameter of 9 μm and a total length of about 40 m. It is said.

  The light emitted from the wavelength conversion unit 30 enters the optical filter 40. The optical filter 40 suppresses the transmission of the light amplified by the amplification optical fiber 22, transmits the primary scattered light of the light, and further suppresses the transmission of the secondary scattered light of the light. That is, the optical filter 40 is a band-pass filter that transmits the primary scattered light. As described above, when light having a wavelength of 1064 nm, primary scattered light having a wavelength of 1120 nm, and secondary scattered light having a wavelength of 1175 nm are emitted from the wavelength conversion unit, for example, light having a wavelength of 1090 nm or less and wavelength of 1150 nm The above transmission of light is suppressed. Further, as described above, when light having a wavelength of 1080 nm, primary scattered light having a wavelength of 1135 nm, and secondary scattered light having a wavelength of 1190 nm are emitted from the wavelength conversion unit, the light having a wavelength of 1105 nm or less and the wavelength of 1165 nm are emitted. The above transmission of light is suppressed.

  An example of such an optical filter 40 is an optical filter in which a filter film is formed on glass. An example of such a filter film is a dielectric multilayer film in which a plurality of types of dielectric films are repeatedly laminated. The optical filter 40 is preferably disposed with the filter surface inclined with respect to the traveling direction of the light emitted from the amplification optical fiber 22. This is because when the optical filter 40 reflects non-transmitted light, the reflected light can be easily taken out by arranging the filter surface inclined.

  Next, the operation of such a fiber laser device 1 will be described.

  FIG. 2 is a diagram illustrating a pulse time waveform and a wavelength of light propagating through the fiber laser device 1. Specifically, FIG. 2 shows a pulse time waveform and a wavelength for each of the light emitted from the seed light source 10, the light emitted from the amplifier unit 20, the light emitted from the wavelength conversion unit 30, and the light emitted from the optical filter 40. Is shown. In each of the diagrams showing the pulse time waveform and the wavelength, the vertical axis indicates the power density of light, and the horizontal axis indicates time. In the following description, a case where light having a wavelength of 1064 nm is emitted from the seed light source will be described.

  First, the Q switch 12 of the seed light source 10 performs a switching operation so as to repeat a low loss state and a high loss state of light at a predetermined fixed period. And the light radiate | emitted from the continuous light generation part 11 is made into the pulse-shaped light synchronized with this switching operation | movement, and the pulse-shaped seed light radiate | emits from the seed light source 10 with a fixed period. As shown in FIG. 2, the pulse time waveform of the seed light emitted from the seed light source 10 using the Q switch 12 has a Gaussian distribution shape. The wavelength of the seed light emitted from the seed light source 10 is 1064 nm as described above. The seed light emitted from the seed light source 10 propagates through the core of the optical fiber 15 and enters the core of the amplification optical fiber 22 from the optical coupler 23.

  The duty ratio of the seed light is, for example, “periodic time when seed light is emitted from the seed light source 10”: “period during which seed light is emitted from the seed light source 10 (length of pulse width of seed light). Is 10: 1. In the present embodiment, the length of the pulse width of the light is set such that the length of the pulse width of the light emitted from the fiber laser device 1 is not less than 100 nsec and not more than 400 nsec, as will be described later.

  In addition, excitation light is emitted from each laser diode of the excitation light source 21. As described above, the wavelength of the excitation light emitted from each laser diode of the excitation light source 21 is, for example, 915 nm. The excitation light emitted from each laser diode propagates through the optical fiber 25 and enters the inner cladding of the amplification optical fiber 22 from the optical coupler 23.

  Thus, the seed light incident on the core of the amplification optical fiber 22 from the optical coupler 23 propagates through the core, and the excitation light incident on the inner cladding of the amplification optical fiber mainly propagates through the inner cladding. In the amplification optical fiber 22, when the excitation light passes through the core, it is absorbed by the rare earth element added to the core, and the rare earth element is excited. In the period when the seed light is not incident on the amplification optical fiber 22, the excited state of the rare earth element is high. On the other hand, when the pulsed seed light is incident on the amplification optical fiber 22, the excited rare earth element causes stimulated emission by the seed light, and the power of the seed light is amplified by this stimulated emission. Pulsed light is emitted. When light with a pulse time waveform having a Gaussian distribution is incident, the amplification optical fiber 22 emits light with a Gaussian distribution having a power density amplified with respect to the incident light. Therefore, as shown in FIG. 2, light having a Gaussian distribution shape in which the pulse time waveform extends the seed light in the power density direction is emitted from the amplification optical fiber 22.

  The light emitted from the amplification optical fiber 22 enters the wavelength conversion unit 30. In the wavelength conversion unit 30, a light component having a power density higher than a specific power density in the incident light is used as primary scattered light having a wavelength of 1120 nm. Further, among the light that is the primary scattered light in the wavelength conversion unit 30, the light component having a higher power density is the secondary scattered light having a wavelength of 1175 nm. The wavelength conversion unit 30 emits light that is not wavelength-converted, primary scattered light, and secondary scattered light. The pulse time waveform of the light emitted from the wavelength conversion unit 30 is the same as the pulse time waveform of the light emitted from the amplification optical fiber 22. Among these, as shown in FIG. 2, the light with a wavelength of 1064 nm that is not wavelength-converted is light with a low power density including a tail portion in the Gaussian distribution shape, and the light with a wavelength of 1175 nm that is secondary scattered light has a Gaussian distribution shape. Light with high power density including the apex. The remaining light having a wavelength of 1120 nm, which is the primary scattered light, is light having a substantially rectangular pulse time waveform sandwiched between light that is not wavelength-converted and secondary scattered light.

  The light emitted from the wavelength conversion unit 30 enters the optical filter 40 that is a bandpass filter. As described above, the optical filter 40 suppresses transmission of the light emitted from the amplification optical fiber 22 and the secondary scattered light of this light, and transmits the primary scattered light of this light. Therefore, the light of wavelength 1120 which is the primary scattered light is transmitted through the optical filter 40, and the transmission of light having a wavelength of 1064 nm having a low power density and light having a wavelength of 1175 nm having a high power density is suppressed. Accordingly, light having a substantially rectangular pulse time waveform is emitted from the optical filter 40. In FIG. 2, light having a wavelength of 1060 nm and light having a wavelength of 1175 nm, whose transmission is suppressed by the optical filter 40, are indicated by broken lines. Further, the pulse width of the light emitted from the optical filter 40 is set to 100 nsec or more and 400 nsec or less.

  The light transmitted through the optical filter 40 is emitted from the fiber laser device 1 without being further amplified, and is irradiated on the workpiece 100. The workpiece 100 absorbs light having a wavelength of 1120 nm. Therefore, the workpiece 100 is processed. Examples of the material of the workpiece that absorbs light having a wavelength of 1120 nm in this way include ZnO, Si, Ge, and Cu—Ln—Ga—Se. In particular, when the workpiece 100 is a material that absorbs light having a wavelength of 1120 nm at 5 to 50%, the pulse width is a long pulse width of 100 nsec or more as described above. It can be processed by intruding light.

  In the above description, the case where light having a wavelength of 1064 nm is emitted from the seed light source has been described. For example, in the case where light having a wavelength of 1080 nm is emitted from the seed light source, the wavelength of the primary scattered light is set to 1135 nm in the above description. The wavelength of the secondary scattered light may be 1190 nm. Examples of the material of the workpiece that absorbs light having a wavelength of 1135 nm include Si, SnO, and ITO (indium tin oxide). In particular, when the material of the workpiece 100 is Si or SnO, the absorptance at a wavelength of 1135 nm can be set to 5 to 50%. In this case as well, the light penetrates to a deep position of the workpiece 100. Can be processed.

  As described above, in the fiber laser device 1 of the present embodiment, since the seed light that has been pulsed by the Q switch is amplified, the pulse time waveform of the amplified light also has a substantially Gaussian distribution shape. . Then, the optical filter 40 suppresses transmission of light with low power density (light that has not undergone wavelength conversion) including a tail portion in the Gaussian distribution shape, so that the power density of emitted light rises sharply and falls sharply. The optical filter 40 also suppresses transmission of light with high power density (light that is assumed to be secondary scattered light) including the apex portion in the Gaussian distribution shape. Therefore, a constant power density can be maintained from the rise of the power density to the fall of the power density. This is not so different even when the pulse width is long. Thus, according to the fiber laser device 1 of the present embodiment, even a light having a long pulse width can emit light having a substantially rectangular pulse time waveform, and the workpiece 100 is processed with this light. It can be carried out.

(Second Embodiment)
Next, a second embodiment of the present invention will be described in detail with reference to FIG. Note that, unless otherwise specified, the same or equivalent components as those of the first embodiment are denoted by the same reference numerals, and redundant description is omitted.

  The fiber laser device of this embodiment is different from the fiber laser device 1 shown in FIG. 1 in that the optical filter 40 transmits the secondary scattered light generated in the wavelength conversion unit 30, and the other configuration is the fiber shown in FIG. This is the same as the laser device 1. That is, while the optical filter 40 of the first embodiment is a bandpass filter, the optical filter 40 of the fiber laser device of this embodiment is a highpass filter.

  FIG. 3 is a diagram showing a pulse time waveform and a wavelength of light propagating through the fiber laser device according to the present embodiment by the same method as in FIG. As shown in FIG. 3, in the fiber laser device of this embodiment, the light emitted from the wavelength conversion unit 30 is the same as that of the fiber laser device 1 of the first embodiment. Accordingly, light that is not wavelength-converted, primary scattered light, and secondary scattered light are incident on the optical filter 40. In the optical filter 40, since transmission of light that is not wavelength-converted is suppressed, primary scattered light and secondary scattered light are emitted from the optical filter 40.

  The emitted light is applied to the workpiece 100. However, the workpiece 100 of the present embodiment is made of a material that absorbs primary scattered light but transmits secondary scattered light. As such a material, as exemplified in the first embodiment, when the wavelength of the primary scattered light is 1120 nm and the wavelength of the secondary scattered light is 1175 nm, for example, ZnO, Si, Ge, Cu—In—Ga. -Se. Further, as such a material, when the wavelength of the primary scattered light is 1135 nm and the wavelength of the secondary scattered light is 1190 nm, for example, Si, SnO, and ITO can be cited.

  As shown in FIG. 3, the pulse time waveform of the primary scattered light is substantially rectangular as in the first embodiment. Therefore, even with the fiber laser device of this embodiment, by selecting the workpiece 100, even when the pulse width is long, processing can be performed with light having a substantially rectangular pulse time waveform.

  The present invention has been described above by taking the first and second embodiments as examples, but the present invention is not limited to these.

  For example, the wavelength of light is not limited to the wavelength exemplified in the above embodiment. Moreover, the wavelength conversion unit 30 does not need to be comprised from an optical fiber. Further, the optical filter 40 may be made of a material other than the dielectric multilayer film.

  The pulse width of light may be shorter than 100 nsec or may be longer than 500 nsec. However, by processing with light having a long pulse width of 100 ns or more, the material having a low primary scattered light absorption rate can be processed to a deep position. In addition, a light pulse width of 500 nsec or less can be easily obtained by Q switch transmission.

  As described above, according to the present invention, there is provided a fiber laser device that can perform processing with light having a substantially rectangular pulse time waveform even when the pulse width is long. It is expected to be used in the field of laser light such as equipment.

DESCRIPTION OF SYMBOLS 1 ... Fiber laser apparatus 5 ... Light emission part 10 ... Seed light source 12 ... Q switch 20 ... Amplifier part 21 ... Excitation light source 22 ... Optical fiber 25 for amplification ... Optical fiber 30 ... wavelength conversion unit 40 ... optical filter 100 ... workpiece

Claims (5)

A seed light source that emits light of a predetermined wavelength pulsed by a Q switch;
An amplification optical fiber that amplifies the light of the predetermined wavelength emitted from the seed light source;
A wavelength conversion unit that generates primary scattered light and secondary scattered light of the predetermined wavelength emitted from the amplification optical fiber by stimulated Raman scattering; and
An optical filter that receives light emitted from the wavelength conversion unit, transmits the primary scattered light, and suppresses transmission of the light of the predetermined wavelength and the secondary scattered light;
A fiber laser device comprising: A seed light source that emits light of a predetermined wavelength pulsed by a Q switch;
An amplification optical fiber that amplifies the light of the predetermined wavelength emitted from the seed light source;
A wavelength conversion unit that generates primary scattered light and secondary scattered light of the predetermined wavelength emitted from the amplification optical fiber by stimulated Raman scattering; and
An optical filter that receives light emitted from the wavelength conversion unit, transmits the primary scattered light and the secondary scattered light, and suppresses transmission of light of the predetermined wavelength; and
With
The light emitted from the filter is irradiated to a workpiece that absorbs the primary scattered light and transmits the secondary scattered light. 3. The fiber laser device according to claim 1, wherein a pulse width of the primary scattered light is 100 nsec or longer. 4. The fiber laser device according to claim 3, wherein the length of the pulse width of the primary scattered light is 500 nsec or less.   A method of processing a workpiece using a fiber laser device,
  The seed light source emits light of a predetermined wavelength that is pulsed by a Q switch,
  Amplifying the light of the predetermined wavelength emitted from the seed light source with an amplification optical fiber;
  The primary scattered light and the secondary scattered light emitted from the amplification optical fiber are generated by stimulated Raman scattering in the wavelength conversion unit, and
  In the optical filter on which the light emitted from the wavelength conversion unit is incident, the first scattered light and the second scattered light are transmitted and the transmission of the light having the predetermined wavelength is suppressed.
  The light emitted from the filter is irradiated to a workpiece that absorbs the primary scattered light and transmits the secondary scattered light.
A processing method for a workpiece characterized by the above.

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