JP2005007476A - Laser beam machining method and laser beam machining device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To stably perform homogeneous machining without depending upon the polarization direction. <P>SOLUTION: By this laser beam machining, the fundamental wave laser beam 3 is passed through two non-linear optical crystals 1A, 1B for changing wavelength which are arranged in series and the changed wavelength laser beam 3C the wavelength of which is changed so that the polarization directions are different directions each other in the range of 45-90° irradiates a material 17 to be machined. This laser beam machining device is provided with the wavelength changing device for changing the wavelength which is provided with a laser beam source 2 for generating the fundamental wave laser beam and two non-linear optical crystals for changing the wavelength which are arranged in series and with which the wavelength is changed so that the polarization directions are different each other in the range of 45-90° with two respective non-linear optical crystals by passing the fundamental wave laser beam through that two nonlinear optical crystals and an irradiating device for irradiating the material to be machined with the changed wavelength laser beam, the wavelength of which is changed with the wavelength changing device. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a laser processing method and a laser processing apparatus for processing a workpiece by irradiating the workpiece with a wavelength-converted laser beam.

Prior art
As a conventional laser processing method, for example, in a method of improving the film quality by irradiating a laser beam on amorphous silicon, the amorphous silicon is irradiated with a double wave of a Q-switched YAG laser (for example, see Patent Document 1). .)

Prior art 2.
As another conventional laser processing method, for example, in a method of crystallizing amorphous silicon by irradiating a laser beam to amorphous silicon, the fundamental wave, second harmonic, third harmonic, or fourth of YAG laser is used. The laser beam is processed and irradiated so that the shape of the irradiated surface when the laser beam is irradiated to the object to be processed is linear (for example, refer to Patent Document 2).

Japanese Unexamined Patent Publication No. Sho 63-314862 (Page 2, Figures 1 and 3) JP 2001-144027 A (page 4-5, FIG. 2)

  In the conventional laser processing method, in the case of irradiating the wavelength conversion laser beam from the wavelength conversion laser device including the wavelength conversion device, the wavelength conversion laser beam emitted from the wavelength conversion laser device (wavelength conversion device) is usually Since it was linearly polarized light, there were problems such as a difference in processing result depending on the processing direction and the polarization direction. In particular, in a process for forming polysilicon by irradiating a laser beam to amorphous silicon and annealing it, when a device such as a thin film transistor is formed using a substrate that has been polysiliconized by a conventional laser processing method, the laser beam There is a problem that the characteristics differ depending on the relationship between the scan direction and the polarization direction.

  The present invention has been made to solve the above-described problems of the prior art, and provides a laser processing method and a laser processing apparatus capable of stably performing homogeneous processing independent of the polarization direction. For the purpose.

  In the laser processing method according to the present invention, a fundamental laser beam is passed through two nonlinear optical crystals for wavelength conversion arranged in series, and the polarization directions of the two nonlinear optical crystals are within a range of 45 ° to 90 ° with each other. The workpiece is irradiated with a wavelength-converted laser beam that has been wavelength-converted so as to have different directions.

  A laser processing apparatus according to the present invention includes a laser light source that generates a fundamental laser beam and two wavelength-converting nonlinear optical crystals arranged in series, and the fundamental laser beam is converted into the two nonlinear optical crystals. A wavelength conversion device that converts the polarization directions of the respective nonlinear optical crystals so that the directions of polarization are different from each other in a range of 45 ° to 90 °, and a wavelength-converted laser beam that has been wavelength-converted by the wavelength conversion device. And an irradiation device for irradiating an object.

  As described above, according to the present invention, the fundamental laser beam is passed through two nonlinear optical crystals for wavelength conversion arranged in series, and the polarization directions of the two nonlinear optical crystals are 45 ° to 90 ° to each other. Since the workpiece is irradiated with the wavelength-converted laser beam that has been wavelength-converted so as to have different directions in the range, there is an effect that uniform processing independent of the polarization direction can be stably performed.

  A laser light source that generates a fundamental laser beam; and two nonlinear optical crystals for wavelength conversion that are arranged in series, and the fundamental laser beam is passed through the two nonlinear optical crystals to each nonlinear optical crystal. A wavelength conversion device that converts wavelengths so that polarization directions are different from each other in a range of 45 ° to 90 °, and an irradiation device that irradiates a workpiece with a wavelength-converted laser beam wavelength-converted by the wavelength conversion device. Therefore, there is an effect that uniform processing independent of the polarization direction can be performed stably.

Embodiment 1 FIG.
1 and 2 are diagrams for explaining a laser processing method and a laser processing apparatus according to Embodiment 1 of the present invention. More specifically, FIG. 1 is a side view showing the laser processing apparatus, and FIG. (A), (b), and (c) are the top view, side view, and perspective view which expand and show the nonlinear optical crystal for wavelength conversion of FIG. 1, respectively.

  In FIG. 1, a laser processing apparatus includes a laser light source 2 for generating a fundamental wave laser beam 3 and two nonlinear optical crystals for wavelength conversion (hereinafter also referred to as wavelength conversion crystals) 1A arranged in series. Conversion device for converting the wavelength of the fundamental laser beam 3 through the two nonlinear optical crystals 1A and 1B so that the polarization directions of the nonlinear laser crystals 1A and 1B are different from each other by about 90 °. And an irradiation device for irradiating the workpiece 17 with the wavelength-converted laser beam 3C wavelength-converted by the wavelength conversion device.

The wavelength conversion device includes wavelength conversion crystals 1A and 1B, and a separation mirror 6 that reflects the fundamental laser beam 3 and transmits the wavelength conversion laser beam 3C. The wavelength conversion crystals 1A and 1B are arranged in series with respect to the optical axis of the laser light source 2 on the temperature controllers 4A and 4B, respectively, and the separation mirror 6 is arranged on the mirror holder 7.
The laser light source 2 and the wavelength conversion device constitute a wavelength conversion laser device, and the laser light source 2, the temperature controllers 4 </ b> A and 4 </ b> B, and the mirror holder 7 are arranged on a common base 5.
The irradiation device includes a reflection mirror 12, a condensing optical system 14, and a processing table 18. The reflecting mirror 12 held by the mirror holder 13 and the condensing optical system 14 held by the optical system holder 15 are held by a fixing jig 16, and the fixing jig 16 is fixed to a processing table 18. Yes. A workpiece 17 such as silicon, a metal plate, a ceramic, a printed board, and a green sheet is held on the processing table 18.

The laser light source 2 has, for example, Nd: YAG (neodymium yag) as an active medium, and generates a fundamental laser beam 3 having a wavelength of 1064 nm with random polarization. The random polarization referred to in the present invention is a polarization state in which the polarization direction is not aligned in one direction like linear polarization, and includes a polarization state including a plurality of polarization direction components and a non-polarization state. .
The wavelength conversion crystals 1A and 1B are made of nonlinear optical crystals such as lithium borate (chemical formula: LiB ₃ O ₅ , abbreviation: LBO).

First, the operation of the wavelength conversion laser device (wavelength conversion device) will be described with reference to FIG. A fundamental laser beam 3 generated from the laser light source 2 and serving as a fundamental wave for wavelength conversion is incident on the preceding wavelength conversion crystal 1A, and a part of the fundamental wave / harmonic mixed laser beam is wavelength-converted to a harmonic. 3A. The fundamental wave / harmonic mixed laser beam 3A is incident again on the wavelength conversion crystal 1B in the subsequent stage, and becomes a fundamental wave / harmonic mixed laser beam 3B in which a part of the fundamental wave component is wavelength-converted into a harmonic. The fundamental wave / harmonic mixed laser beam 3B is incident on the separation mirror 6, the fundamental wave component is reflected and incident on a damper or the like not shown in the figure, and only the harmonic component is transmitted, and the wavelength conversion laser. The beam 3C is extracted outside the wavelength conversion laser device (wavelength conversion device).
Thus, in the wavelength conversion laser device (wavelength conversion device) according to the present embodiment, the fundamental wave laser beam travels in one direction, and wavelength conversion is performed by the wavelength conversion nonlinear optical crystal (wavelength conversion crystals 1A and 1B). .

Next, the arrangement method of the wavelength conversion crystals 1A and 1B will be described in detail with reference to FIG. Here, an Nd: YAG (neodymium yag) laser that generates a fundamental wave laser beam 3 of random polarization and a wavelength of 1064 nm is used as the laser light source 2, and a fundamental wave laser beam is used as the wavelength conversion crystals 1A and 1B by type 2 phase matching. 3 shows a case where a lithium borate (chemical formula: LiB ₃ O ₅ , abbreviation: LBO) crystal that converts a part of 3 into a second harmonic wave having a wavelength of 532 nm is used.
In this case, the fundamental wave laser beam 3 is oriented in the direction of about 20.5 ° from the crystal orientation axis c in the planes 9A and 9B formed by the crystal orientation axis b and the crystal orientation axis c perpendicular to the crystal orientation axis a of the lithium borate crystal. To satisfy the type 2 phase matching condition of the fundamental wave and the second harmonic, and a part of the randomly polarized fundamental wave laser beam 3 is wavelength-converted to obtain the second linearly polarized light along the crystal orientation axis a direction. Harmonics are generated.

In the present embodiment, the length in the laser beam passing direction of the preceding wavelength conversion crystal 1A through which the fundamental laser beam passes first and the subsequent wavelength conversion crystal 1B through which the fundamental laser beam passes later are different, The length of the subsequent wavelength conversion crystal 1B is longer than the length of the previous wavelength conversion crystal 1A.
Further, the wavelength conversion crystal 1A is arranged so that the crystal orientation axis a is in the horizontal direction (perpendicular to the paper surface of FIG. 1), and the wavelength conversion crystal 1B is arranged in the vertical direction (with respect to the paper surface of FIG. 1). (Parallel direction). In this way, when two wavelength conversion crystals 1A and 1B are used in series, the crystal orientation axis of the other wavelength conversion crystal 1B is 90 ° with respect to one wavelength conversion crystal 1A with the optical axis of the laser beam 3 as the center. The direction of polarization of the second harmonic generated from the wavelength conversion crystal 1A by rotating (ie, arranging so that the crystal orientation axes are 90 ° different from each other when viewed from the optical axis direction of the laser beam) And the polarization direction of the second harmonic generated from the wavelength conversion crystal 1B differs by 90 °. As a result, wavelength conversion laser beams 3C whose polarization directions are different from each other by about 90 ° are generated.

  Next, laser processing will be described. The wavelength conversion laser beam 3C generated from the wavelength conversion laser device (wavelength conversion device) is reflected by the reflection mirror 12, focused on the workpiece 17 by the focusing optical system 15, and annealed to the workpiece 17. Processes such as surface modification, drilling, cutting, welding, trimming, etc.

  As described above, in the first embodiment, the wavelength conversion laser beam 3C generated from the wavelength conversion laser device (wavelength conversion device) has a polarization direction different by 90 °, that is, the wavelength conversion laser beam 3C is horizontal. It includes a polarization component in the direction (perpendicular to the paper surface in FIG. 1) and a polarization component in the vertical direction (parallel to the paper surface in FIG. 1). Therefore, there is an effect that it is possible to stably perform processing (that is, constant regardless of the polarization direction and the processing point (location)).

  In the first embodiment, the wavelength conversion laser device (wavelength conversion device) includes the polarization direction of the second harmonic (wavelength conversion laser beam) generated from the wavelength conversion crystal 1A and the second direction generated from the wavelength conversion crystal 1B. Since the polarization directions of the harmonics (wavelength-converted laser beams) are different by 90 °, interference between the second harmonics does not occur, so that the high-power wavelength-converted laser beam 3C can be generated efficiently and stably. it can. As described above, since the high-power wavelength-converted laser beam 3C can be generated with high efficiency and stability, the processing can be efficiently performed stably and accurately for a long period of time (that is, constant in time). There is an effect.

  Further, the power of the fundamental wave component of the fundamental wave / harmonic mixed laser beam 3A incident on the wavelength conversion crystal 1B is smaller than the power of the fundamental laser beam 3 incident on the wavelength conversion crystal 1A. In the first embodiment, the length in the laser beam passing direction in the latter wavelength conversion crystal 1B is longer than the length in the laser beam passing direction in the first wavelength conversion crystal 1A. The power of the second harmonic and the power of the second harmonic generated from the subsequent wavelength conversion crystal 1B can be made close to each other. Thus, since the power of the second harmonic generated from the wavelength conversion crystal 1A at the front stage and the power of the second harmonic generated from the wavelength conversion crystal 1B at the rear stage can be made close to each other, the wavelength conversion laser beam 3C Can be brought into a polarization state closer to random polarization, and more uniform processing independent of the polarization direction can be stably performed.

Hereinafter, specific experimental examples (Example 1 and Comparative Example 1) will be shown to further explain the effects of the present embodiment.
Example 1.
As the laser light source 2, an Nd: YAG (Neodymium / Yag) laser that generates a fundamental laser beam 3 having a wavelength of 1064 nm by random polarization and oscillating a Q switch pulse was used. The conditions of the laser beam 3 were an average power of 529 W, a pulse repetition frequency of 4 kHz, a pulse width of 40.4 ns, and a beam quality M ² ≈10.
As the wavelength conversion crystals 1A and 1B, lithium borates (chemical formula: LiB ₃ O ₅ ) having a length of 15 mm and 18 mm in the laser beam passing direction, which generate the second harmonic by the type 2 phase matching, are fundamental. The 1 / e ² radii of the wave laser beam 3 were arranged at positions of 0.54 mm and 0.52 mm.

  As the direction of the wavelength conversion crystal 1A, 1B, the crystal orientation axis a of the wavelength conversion crystal 1A is arranged in the horizontal direction as shown in FIG. 2, and the crystal orientation axis a of the wavelength conversion crystal 1B is in the vertical direction. When arranged, an average output of 186 W of the second harmonic wavelength conversion laser beam 3C was obtained. When the power of each of the second harmonic wavelength conversion laser beams was measured by polarization separation, the power of the polarization component generated from the wavelength conversion crystal 1A was 95 W, and the power of the polarization component generated from the wavelength conversion crystal 2A was 91 W. The wavelength conversion laser beam 3C had almost the same power and was in a polarization state close to random polarization. Further, the fluctuation of the average output of the second harmonic wavelength conversion laser beam 3C was very stable at about ± 1%. When amorphous silicon was irradiated with this wavelength conversion laser beam 3C to form polysilicon, the device characteristics did not depend on the polarization direction.

Comparative Example 1
On the other hand, as a comparative example, only the direction of the wavelength conversion crystals 1A and 1B is different from that of Example 1, and in any wavelength conversion crystal 1A and 1B, when the crystal orientation axis a is arranged in the horizontal direction, The average output of the harmonic wavelength conversion laser beam 3C was 138 W, which was about 23% lower than that of the present example. Further, the fluctuation of the average output of the second harmonic wavelength conversion laser beam 3C was very unstable at about ± 10%. Further, since the crystal orientation axis directions of the two wavelength conversion crystals 1A and 1B were aligned, the wavelength conversion laser beam 3C was linearly polarized light. When the amorphous silicon was irradiated with this wavelength conversion laser beam 3C to form polysilicon, there was a difference in device characteristics depending on the relationship between the scan direction and the polarization direction.

  As a result of this experiment, it is clear that uniform processing independent of the polarization direction can be performed stably by irradiating the workpiece with wavelength-converted laser beams whose polarization directions are different from each other by 90 ° instead of linearly polarized light. became.

  In the first embodiment, the wavelength conversion crystal 1A is arranged so that the crystal orientation axis a is in the horizontal direction, and the wavelength conversion crystal 1B is arranged so that the crystal orientation axis a is in the vertical direction. However, conversely, the wavelength conversion crystal 1A may be arranged so that the crystal orientation axis a is vertical, and the wavelength conversion crystal 1B may be arranged so that the crystal orientation axis a is horizontal. The crystal may be arranged so that the polarization direction of the wavelength conversion laser beam generated in the conversion crystal 1A and the polarization direction of the wavelength conversion laser beam generated in the wavelength conversion crystal 1B are 90 ° different from each other. An effect is obtained.

  In the first embodiment, the case where the workpieces 17 are irradiated with the wavelength conversion laser beams whose polarization directions are different by 90 ° from each other has been described. However, the polarization direction includes polarized light components that cross each other and is polarized light that is close to random polarization. In addition, the polarization direction is an angle that is different so that the influence of interference between the wavelength conversion laser beam generated in the preceding wavelength conversion crystal 1A and the wavelength conversion laser beam generated in the subsequent wavelength conversion crystal 1B is reduced. Therefore, the directions do not have to be different from each other by exactly 90 °, and the polarization directions may be different from each other in the range of 45 ° to 90 °. Desirably about 90 ° (for example, in the range of 85 ° to 90 ° (output decrease due to interference is 10% or less), more preferably in the range of 88 ° to 90 ° (output decrease due to interference is 5%). It will be as follows)))

  In addition, the two wavelength conversion crystals 1A and 1B are arranged so that the crystal azimuth axes are different from each other by 90 ° when viewed from the optical axis direction of the laser beam. The crystal orientation axes of the two wavelength conversion crystals 1A and 1B may be different from each other within a range of 45 ° to 90 °. Desirably, it should be approximately 90 ° (for example, a range of 85 ° to 90 °, more preferably a range of 88 ° to 90 °).

  In the present invention, when the smaller one of the angles formed by the crystal orientation axes of the two wavelength conversion crystals 1A and 1B is 45 °, the crystal orientation axes of the two wavelength conversion crystals 1A and 1B differ by 45 °. The angle between the polarization direction of the wavelength conversion laser beam converted by the wavelength conversion crystal 1A and the polarization direction of the wavelength conversion laser beam converted by the wavelength conversion crystal 1B is 45 °. In some cases, the polarization directions are 45 ° different from each other.

Embodiment 2. FIG.
3 and 4 are diagrams for explaining a laser processing method and a laser processing apparatus according to Embodiment 2 of the present invention. More specifically, FIG. 3 is a side view showing the laser processing apparatus, and FIG. FIG. 4 is an enlarged perspective view showing the wavelength conversion crystal and the wave plate of FIG. 3.
In the present embodiment, the two wavelength conversion crystals 1A and 1B are arranged in series so that the crystal orientation axes a are in the same direction when viewed from the optical axis direction of the laser beam, and the two nonlinear optical crystals 1A. Wavelength plate 10 is disposed as a polarization direction rotating means for rotating the polarization direction of the laser beam whose wavelength is converted by 90 ° between 1 and 1B. Since the other configuration is the same as that of the first embodiment, differences from the first embodiment will be mainly described below.

  In the wavelength conversion laser device shown in FIG. 3, a wave plate 10 for rotating the polarization direction of the harmonic component of the fundamental wave / harmonic mixed laser beam 3A by 90 ° about the optical axis is held by a holder 11, and wavelength conversion crystal It is arrange | positioned on the base 5 between 1A and the wavelength conversion crystal 1B. The wave plate 10 is formed of, for example, a half-wave plate, and its crystal orientation axis is rotated by 45 ° around the optical axis of the laser beam 3 with respect to the crystal orientation axis a of the wavelength conversion crystals 1A and 1B.

FIG. 4 shows an Nd: YAG (Neodymium Yag) laser that generates a fundamental laser beam 3 of 1064 nm with random polarization as the laser light source 2, and a fundamental laser beam by type 2 phase matching as the wavelength conversion crystals 1A and 1B. 3 shows the case of using a lithium borate (chemical formula: LiB ₃ O ₅ , abbreviation: LBO) crystal that converts a part of the wavelength to a second harmonic of a wavelength of 532 nm, and both the wavelength conversion crystals 1A and 1B have crystal orientation axes. They are arranged so that a is in the horizontal direction (perpendicular to the paper surface of FIG. 3).

In this configuration, the harmonic component of the fundamental / harmonic mixed laser beam 3A is rotated by 90 ° about the optical axis by the half-wave plate 10 and incident on the wavelength conversion crystal 1B. Therefore, the polarization direction of the second harmonic generated from the wavelength conversion crystal 1A and incident on the wavelength conversion crystal 1B is different from the polarization direction of the second harmonic generated from the wavelength conversion crystal 1B by 90 °. That is, as the wavelength conversion laser beam 3C, laser beams whose polarization directions are different from each other by about 90 ° are generated.
Therefore, the same effects as those of the first embodiment can be obtained in the second embodiment.

  In the second embodiment, the configuration using the half-wave plate 10 as the polarization direction rotating means for rotating the polarization direction of the wavelength-converted laser beam by about 90 ° has been described. An optical rotation plate or an electro-optical element may be used instead of 10, and the same effect can be obtained.

In the second embodiment, the configuration in which the crystal orientation axes a of the two wavelength conversion crystals 1A and 1B are arranged in the same direction as seen from the optical axis direction of the laser beam is shown. The same effect as in the second embodiment can be obtained.
Further, the angle between the crystal orientation axes of the wavelength conversion crystals 1A and 1B is less affected by interference between the wavelength conversion laser beam generated in the preceding wavelength conversion crystal 1A and the wavelength conversion laser beam generated in the subsequent wavelength conversion crystal 1B. It is not necessary for the direction to be exactly the same direction or exactly 180 degrees different from each other, and it is sufficient that the direction is approximately the same direction or approximately 180 degrees, for example, 5 degrees from the same direction or 180 degrees different directions. Within a range of preferably within 2 °.
The same applies to the polarization direction rotating means, and it does not have to be rotated exactly 90 °, and may be in the range of 45 ° to 90 °. Desirably, it may be approximately 90 ° (for example, in the range of 85 ° to 90 °, more preferably in the range of 88 ° to 90 °).
In short, as in the case of the first embodiment, the polarization direction of the wavelength conversion laser beam 3C irradiated to the workpiece (that is, the wavelength conversion laser beam generated by the wavelength conversion crystal 1A and incident on the wavelength conversion crystal 1B) And the polarization direction of the wavelength-converted laser beam generated in the wavelength conversion crystal 1B may be different from each other in the range of 45 ° to 90 °. Desirably, it should be approximately 90 ° (for example, a range of 85 ° to 90 °, more preferably a range of 88 ° to 90 °).

Embodiment 3 FIG.
5 and 6 are diagrams for explaining a laser processing method and a laser processing apparatus according to Embodiment 3 of the present invention, and more specifically, are side views of the laser processing apparatus.
In the present embodiment, a ¼ wavelength plate 19 is provided as circular polarization means for converting the wavelength conversion laser beam 3C into circularly polarized light. Since the other configuration is the same as that of the first embodiment, differences from the first embodiment will be mainly described below.

  The quarter wave plate 19 is fixed to the holder 20 and disposed on the base 5 </ b> A, and the base 5 </ b> A is fixed to the base 5. In FIG. 5, the base 5 </ b> A is configured separately from the base 5, but needless to say, it may be configured integrally.

  In such a configuration, the wavelength conversion laser beam 3C emitted from the wavelength conversion device (wavelength conversion laser device) is converted into circularly polarized light by the quarter wavelength plate 19 and circularly polarized, thereby converting the wavelength converted laser beam. 3D. Specifically, for example, when a component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3C is converted into clockwise circular polarization by the quarter wavelength plate 19, the component is generated from the wavelength conversion crystal 1B of the wavelength conversion laser beam 3C. The component becomes counterclockwise circularly polarized light by the quarter wavelength plate 19, and becomes a wavelength conversion laser beam 3D in which left and right circularly polarized light are mixed. The circularly polarized wavelength-converted laser beam 3D is reflected by the reflecting mirror 12 and focused and irradiated on the workpiece 17 by the focusing optical system 15, and the workpiece is annealed, surface-modified, drilled, cut, Processing such as welding and trimming.

  As described above, in the third embodiment, in addition to the effects of the first embodiment, the circularly polarized wavelength-converted laser beam 3D is focused and irradiated on the workpiece 17, so the polarization direction There is an effect that it is possible to stably carry out a more uniform processing that does not depend on.

  5 shows the case where the ¼ wavelength plate 19 is inserted into the laser processing apparatus according to the first embodiment, but as shown in FIG. 6, the ¼ wavelength is added to the laser processing apparatus according to the second embodiment. The plate 19 may be inserted, and the same effect can be obtained.

  The means for converting the wavelength conversion laser beam into circularly polarized light is not limited to the quarter wavelength plate 19 and may be, for example, an electro-optic element.

Embodiment 4 FIG.
FIG. 7 is a view for explaining a laser processing method and a laser processing apparatus according to Embodiment 4 of the present invention, and more specifically, a top view of the laser processing apparatus.
In this embodiment, in addition to the laser processing apparatus shown in Embodiment 1, the following are mainly provided.
First, reflecting mirrors 21 and 21A are provided as reflecting means that transmits part of the wavelength conversion laser beam 3D.
Further, the power is monitored as a beam monitor which is a means for monitoring the beam parameters (power, beam profile (beam diameter), beam quality, divergence angle) of the wavelength conversion laser beams 3E and 3F transmitted through the reflection mirrors 21 and 21A. A power monitor 22 as means and a beam profiler 23 as means for monitoring the beam profile are provided.
Still further, the reflecting surface of the reflecting means is arranged in the preceding stage of the reflecting means (reflecting mirrors 21 and 21A), and the polarization state of the wavelength conversion laser beam 3C is changed with respect to the respective wavelength conversion laser beams generated from the respective nonlinear optical crystals 1A and 1B. Polarization state converting means for converting the ratio of the s-polarized component and the p-polarized component to approximately the same, that is, reflecting means for the wavelength-converted laser beam generated from the nonlinear optical crystal 1A through which the fundamental laser beam passes first The ratio of the s-polarized component and the p-polarized component with respect to the reflecting surface, and the s-polarized component and the p-polarized component with respect to the reflecting surface of the reflecting means in the wavelength-converted laser beam generated from the nonlinear optical crystal 1B through which the fundamental laser beam passes later As a polarization state converting means for converting the ratio so that the ratio is approximately the same, a quarter wavelength plate 19 is provided. That. The quarter-wave plate 19 also serves as a circular polarization unit that converts the wavelength-converted laser beam 3C described in the third embodiment into circularly polarized light.
Since the other configuration is the same as that of the first embodiment, differences from the first embodiment will be mainly described below.

  The quarter wave plate 19 is held by the holder 20 and is disposed on the base 5. The reflection mirrors 21 and 21A are held by the mirror holders 7A and 7B and are disposed behind the quarter-wave plate 19 on the base 5. The power monitor 22 is held by the holder 20 </ b> A and is disposed on the base 5 on the back side of the reflection mirror 21. The beam profiler 23 is held by the holder 20B, and is disposed on the base 5 on the back side of the reflecting mirror 21A.

  The irradiation device includes a reflection mirror 12, a condensing optical system 14, and a processing table 18A. The reflecting mirror 12 held by the mirror holder 13A, the condensing optical system 14 held by the optical system holder 15A, and the processing table 18A are fixed to the base 5B. A workpiece 17 such as silicon, a metal plate, a ceramic, a printed board, and a green sheet is held on the processing table 18A.

  In such a configuration, the wavelength conversion laser beam 3C that has passed through the separation mirror 6 is converted into circularly polarized light (circularly polarized) by the quarter wavelength plate 19, so that the polarization state is converted. Thus, the wavelength conversion laser in which the ratio of the s-polarized component and the p-polarized component with respect to the reflecting surface of the reflecting means (reflecting mirrors 21 and 21A) in the respective wavelength-converted laser beams generated from the nonlinear optical crystals 1A and 1B is approximately the same. It becomes a beam 3D. Specifically, for example, when a component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3C is converted into clockwise circular polarization by the quarter wavelength plate 19, the component is generated from the wavelength conversion crystal 1B of the wavelength conversion laser beam 3C. The component becomes counterclockwise circularly polarized light by the quarter wavelength plate 19, and becomes a wavelength conversion laser beam 3D in which left and right circularly polarized light are mixed.

The circularly polarized wavelength-converted laser beam 3D is reflected by the reflection mirrors 21, 21A, and 12, and is condensed and irradiated onto the workpiece 17 by the condensing optical system 14, and the workpiece 17 is annealed and surface-modified. Processing such as quality, drilling, cutting, welding and trimming.
In addition, a part of the circularly polarized wavelength conversion laser beam 3 </ b> D passes through the reflection mirror 21. The wavelength-converted laser beam 3E that has passed through the reflection mirror 21 enters the power monitor 22, and its power is measured. Further, a part of the circularly polarized wavelength conversion laser beam 3D is transmitted through the reflection mirror 21A. The wavelength-converted laser beam 3F transmitted through the reflecting mirror 21A is incident on the beam profiler 23, and the beam profile is measured.

  As described above, in the present embodiment, the quarter wavelength plate 19 is provided as a means for combining the circular polarization means and the polarization state conversion means, and the wavelength conversion laser beam 3C is converted into circular polarization. As in the third embodiment, since the circularly polarized wavelength conversion laser beam 3D is focused and irradiated on the workpiece 17, more uniform processing independent of the polarization direction can be stably performed. There is an effect.

  Further, a power monitor 22 is provided as means for monitoring the power of the wavelength-converted laser beam 3D, and is circularly polarized (the wavelength conversion state generated by each of the nonlinear optical crystals 1A and 1B is changed to the polarization state of the wavelength-converted laser beam 3C). Of the wavelength-converted laser beam 3E, which is a part of the wavelength-converted laser beam 3D (converted so that the ratio of the s-polarized component and the p-polarized component to the reflecting surfaces of the reflecting mirrors 21 and 21A in the laser beam is approximately the same) Since the power is monitored, the power of the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3C is obtained by grasping the relationship between the power of the wavelength conversion laser beam 3E and the power of the wavelength conversion laser beam 3D in advance. And the sum of the powers of the components generated from the wavelength conversion crystal 1B of the wavelength conversion laser beam 3C. URN can be accurately measured. Therefore, the power of the wavelength conversion laser beam 3D output from the wavelength conversion laser device can be measured almost accurately, and it is grasped whether or not a high-efficiency wavelength conversion laser beam is stably generated for a long period of time. can do. For this reason, it is possible to measure the power of the wavelength-converted laser beam 3D irradiated to the workpiece 17 almost accurately, and whether uniform processing (constant in time) can be performed stably over a long period of time. There is an effect that can be grasped.

  Furthermore, a beam profiler 23 is provided as a means for monitoring the beam profile of the wavelength conversion laser beam 3D, and is circularly polarized (the polarization state of the wavelength conversion laser beam 3C is generated from each of the nonlinear optical crystals 1A and 1B. The wavelength-converted laser beam that is part of the wavelength-converted laser beam 3D (converted so that the ratio of the s-polarized component and the p-polarized component to the reflecting surfaces of the reflection mirrors 21 and 21A in the wavelength-converted laser beam is approximately the same) Since the beam profile of 3F is monitored, the sum of the beam profile of the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3C and the beam profile of the component generated from the wavelength conversion crystal 1B can be measured almost accurately. Can do. Therefore, the beam profile of the wavelength conversion laser beam 3D output from the wavelength conversion laser device can be measured almost accurately, and whether or not the wavelength conversion laser beam with high output is stably generated for a long period of time can be determined. I can grasp it. For this reason, it is possible to measure the beam profile of the wavelength-converted laser beam 3D irradiated to the workpiece 17 almost accurately, and whether the processing is stable and accurate and uniform (constant in time) for a long period of time. There is an effect that it is possible to grasp whether or not.

  The polarization state of the wavelength conversion laser beam 3C as described above is expressed by the s-polarized component and the p-polarized component with respect to the reflecting surfaces of the reflecting mirrors 21 and 21A in the respective wavelength-converted laser beams generated from the nonlinear optical crystals 1A and 1B. The effect obtained by monitoring the power or beam profile of a portion of the wavelength converted laser beam 3D that has been converted to be approximately the same (circularly polarized) is that a plurality of straight lines as in the present invention are obtained. This is a unique effect obtained only with a wavelength conversion laser beam in which polarization components are mixed, and cannot be obtained with a general linearly polarized laser beam or a randomly polarized laser beam. Hereinafter, this point will be described in detail.

  In general, when a laser beam is incident on a mirror at an angle other than normal incidence, the reflectivity of the mirror varies depending on the polarization direction of the incident beam, and the reflectivity of s-polarized light is higher than the reflectivity of p-polarized light. That is, the transmittance of s-polarized light is lower than the transmittance of p-polarized light.

  First, as a comparative example, the wavelength conversion laser beam 3E which does not include the quarter wavelength plate 19 and is incident on the reflection mirrors 21 and 21A and is transmitted through the reflection mirrors 21 and 21A. A case where the power and beam profile of 3F are monitored will be described. For example, when wavelength conversion laser beams having polarization directions different from each other by about 90 ° are generated from the wavelength conversion crystals 1A and 1B, the components generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3C are converted into s-polarized and wavelength conversion lasers. If the component generated from the wavelength conversion crystal 1B of the beam 3C is incident on the reflection mirrors 21 and 21A as p-polarized light, the transmittance of s-polarized light is lower than the transmittance of p-polarized light. More power and beam profiles of components generated from the wavelength conversion crystal 1B are monitored than components generated from the wavelength conversion crystal 1A.

Specifically, for example, when the wavelength conversion laser beam 3C is incident on the reflection mirrors 21 and 21A at an incident angle of about 45 °, the transmittance of the s-polarized light of the reflection mirrors 21 and 21A is about 0.1%, for example. The transmittance of the p-polarized light of the reflecting mirrors 21 and 21A is about 0.9%, for example, and about 0.1% of the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3C and the wavelength conversion of the wavelength conversion laser beam 3C. A sum of about 0.9% of the components generated from the crystal 1B enters the power monitor 22 and the beam profiler 23, and the power and beam profile thereof are measured.
Therefore, for example, even if the power or beam profile of only the component generated from the wavelength conversion crystal 1A in the wavelength conversion laser beam 3C changes, the monitor values of the power monitor 22 and the beam profiler 23 change little, and the workpiece 17 A problem arises in that changes in the power and beam profile of the wavelength-converted laser beam applied to the laser beam cannot be accurately monitored.

  However, in the present embodiment, the light is circularly polarized by the ¼ wavelength plate 19 (the polarization state of the wavelength conversion laser beam 3C is reflected in each wavelength conversion laser beam generated from each nonlinear optical crystal 1A, 1B. Since the wavelength-converted laser beam 3D (converted so that the ratio of the s-polarized component and the p-polarized component with respect to the reflecting surfaces of the mirrors 21 and 21A is approximately the same) is incident on the reflecting mirrors 21 and 21A. The s-polarized component and the p-polarized component of the component generated from the wavelength conversion crystal 1A and the component generated from the wavelength conversion crystal 1B of the wavelength conversion laser beam 3D incident on the monitor 22 and the beam profiler 23 are approximately the same, and the wavelength conversion laser. The power of the component generated from the wavelength conversion crystal 1A and the component generated from the wavelength conversion crystal 1B of the beam 3D Thereby monitoring the beam profile in equal proportions approximately.

  Specifically, for example, the transmittance of the s-polarized light of the reflecting mirrors 21 and 21A is about 0.1%, and the transmittance of the p-polarized light of the reflecting mirrors 21 and 21A is about 0.9%. Of the components generated from the wavelength conversion crystal 1A of the converted laser beam 3D, the s-polarized component is about 50% and the p-polarized component is also about 50%, so about 0.1% of the s-polarized component (of the wavelength-converted laser beam 3D) Sum of about 0.05% of the component generated from the wavelength conversion crystal 1A) and about 0.9% of the p-polarized component (about 0.45% of the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D), That is, about 0.5% of the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D is transmitted through the reflection mirrors 21 and 21A. Similarly, since the component generated from the wavelength conversion crystal 1B of the circularly polarized wavelength conversion laser beam 3D is about 50% of the s-polarized component and about 50% of the p-polarized component, the wavelength of the wavelength-converted laser beam 3D About 0.5% of the component generated from the conversion crystal 1B is transmitted through the reflection mirrors 21 and 21A. Therefore, in the wavelength conversion laser beam 3D, the component generated from the wavelength conversion crystal 1A and the component generated from the wavelength conversion crystal 1B are incident on the power monitor 22 and the beam profiler 23 at the same ratio, and the power and beam profile are measured. Will do.

Therefore, the power and beam profile of the wavelength conversion laser beam 3D output from the wavelength conversion laser device can be measured almost accurately, and whether or not the wavelength conversion laser beam having high output stably for a long period of time is generated with high efficiency. I can understand. For this reason, the power and beam profile of the wavelength-converted laser beam 3D irradiated to the workpiece 17 can be measured almost accurately, and processing can be performed stably and accurately for a long period of time with accuracy (constant in time). There is an effect that it can be grasped whether or not.
Further, for example, even if the power or beam profile of only the component generated from the wavelength conversion crystal 1A in the wavelength conversion laser beam 3C changes, the power or beam profile of the wavelength conversion laser beam 3D irradiated to the workpiece 17 changes. The change can be monitored almost accurately, and it is possible to grasp the change in processing due to the change in the power and beam profile of only the component generated from the wavelength conversion crystal 1A in the wavelength conversion laser beam 3D.

On the other hand, in a general linearly polarized laser beam, the polarization direction of the laser beam incident on the reflecting mirrors 21 and 21A is only one of s-polarized light and p-polarized light. The transmittance is constant regardless of whether or not it is circularly polarized. Therefore, there is no new effect by monitoring the power and beam profile of the circularly polarized wavelength conversion laser beam.
Further, in a general random polarization laser beam, since the polarization direction of the laser beam incident on the reflection mirrors 21 and 21A is the same ratio between the s-polarized light and the p-polarized light, before entering the reflection mirrors 21 and 21A. The transmittance is constant regardless of whether or not it is circularly polarized. Therefore, there is no new effect by monitoring the power and beam profile of the circularly polarized wavelength conversion laser beam.

  In the above description, the wavelength conversion laser beams whose polarization directions are different from each other by about 90 ° are generated from the wavelength conversion crystals 1A and 1B, but specific numerical values are given. The same can be said for different cases in the range of 90 °. For example, the wavelength conversion laser beam 3C is passed through a quarter-wave plate 19 which is also a means that also serves as a polarization state conversion means, and of the components generated from the wavelength conversion crystal 1A, the s-polarized component is about 60% and the p-polarized component. Is approximately 40%, of the components generated from the wavelength conversion crystal 1B, the s-polarized component is approximately 60%, the p-polarized component is approximately 40%, and so on. In the wavelength conversion laser beam 3D, the component generated from the wavelength conversion crystal 1A is converted into the wavelength conversion laser beam 3D converted into elliptically polarized light in which the ratio of the s-polarized component and the p-polarized component is approximately the same. Components generated from the wavelength conversion crystal 1B are incident on the power monitor 22 and the beam profiler 23 at the same rate, and the power and beam profile are measured. It becomes door.

  7 shows a configuration in which the wavelength conversion laser beam reflected by the reflection mirrors 21 and 21A is used for processing and the beam parameters of the wavelength conversion laser beam transmitted through the reflection mirrors 21 and 21A are monitored. The wavelength conversion laser beam transmitted through 21A may be used for processing, and the beam parameters of the wavelength conversion laser beam reflected by the reflection mirrors 21 and 21A may be monitored.

  FIG. 7 shows the case where the wavelength conversion laser apparatus according to the first embodiment includes the quarter wavelength plate 19, the reflection mirrors 21 and 21A, the power monitor 22, and the beam profiler 23, but the second embodiment. The laser processing apparatus may include the quarter wavelength plate 19, the reflection mirrors 21 and 21A, the power monitor 22, and the beam profiler 23, and the same effect can be obtained.

  Further, in addition to the configuration shown in FIG. 7, means for adjusting the output of the laser light source 2 according to the monitor value of the power monitor 22, or the temperatures of the temperature controllers 4 </ b> A and 4 </ b> B according to the monitor value of the power monitor 22. By providing the adjusting means and performing feedback control, there is an effect that the power of the wavelength conversion laser beam 3D can be stably kept constant for a long period of time.

Further, since the beam diameter can be obtained from the beam profile measured by the beam profiler 23, in addition to the configuration shown in FIG. 7, for example, by providing a beam diameter adjusting mechanism including a combination of a plurality of lenses, a wavelength conversion laser is provided. The beam diameter of the beam 3D can be adjusted to an arbitrary value and output.
Furthermore, by providing a means for controlling the beam diameter adjusting mechanism according to the beam diameter measured by the beam profiler 23 and performing feedback control, the beam diameter of the wavelength conversion laser beam 3D can be kept stable and constant over a long period of time. There is an effect.

In the fourth embodiment, the case where a means for monitoring power and beam profile among beam parameters (power, beam profile (beam diameter), beam quality, divergence angle) is provided has been described. (M ² value indicating beam condensing property and index value such as beam product) may be provided, and the beam quality of the wavelength conversion laser beam 3D output from the wavelength conversion laser device is measured almost accurately. It is possible to grasp whether or not a high-quality wavelength conversion laser beam is generated stably for a long period of time. For this reason, it is possible to measure the beam quality of the wavelength-converted laser beam 3D irradiated to the workpiece 17 almost accurately, and whether the processing is stable and accurate and uniform (constant in time) for a long period of time. There is an effect that it is possible to grasp whether or not.

  In addition, for example, a divergence angle may be provided by providing a plurality of beam profilers, and the divergence angle of the wavelength conversion laser beam 3D output from the wavelength conversion laser device can be measured almost accurately. It is possible to grasp whether or not a high-quality wavelength conversion laser beam is generated stably for a long period of time. For this reason, it is possible to measure the divergence angle of the wavelength-converted laser beam 3D irradiated to the workpiece 17 almost accurately, and whether the processing is stable and accurate and uniform (constant in time) for a long period of time. There is an effect that it is possible to grasp whether or not.

Embodiment 5 FIG.
FIG. 8 is a view for explaining a laser processing method and a laser processing apparatus according to Embodiment 5 of the present invention, and more specifically, a top view of the laser processing apparatus.
In this embodiment, in addition to the laser processing apparatus shown in Embodiment 1, the following are mainly provided.
First, as a means for adjusting the power of the wavelength conversion laser beam 3D, a variable attenuator 24 having variable transmittance mirrors 25A and 25B and having variable transmittance is provided.
Further, the polarization state of the wavelength-converted laser beam 3C, which is arranged in the previous stage of the variable attenuator 24, changes the polarization state of the wavelength-converted laser beam generated from each nonlinear optical crystal 1A, 1B with respect to the reflecting surface of the reflecting means and the p-polarized light. A ¼ wavelength plate 19 is provided as a polarization state converting means for converting the ratio with the components to be approximately the same. The quarter-wave plate 19 also serves as a circular polarization unit that converts the wavelength-converted laser beam 3C described in the third embodiment into circularly polarized light.
Since the other configuration is the same as that of the first embodiment, differences from the first embodiment will be mainly described below.

The quarter wave plate 19 is fixed to the holder 20 and disposed on the base 5. The variable attenuator 24 is fixed to the holder 20 </ b> C and disposed on the base 5. In the variable attenuator 24, the variable transmittance mirrors 25A and 25B whose transmittance varies depending on the incident angle of the wavelength conversion laser beam 3C, and the incident angle of the wavelength conversion laser beam 3C with respect to the variable transmittance mirrors 25A and 25B are changed. A mechanism for rotating the variable transmittance mirrors 25A and 25B (not shown) is provided.
The configuration of the irradiation apparatus is the same as that of the fourth embodiment.

In such a configuration, the wavelength conversion laser beam 3C that has passed through the separation mirror 6 is converted into circularly polarized light (circularly polarized) by the quarter wavelength plate 19, so that the polarization state is converted. Thus, the ratio of the s-polarized component, the p-polarized component, the s-polarized component, and the p-polarized component with respect to the mirror surfaces of the variable transmittance mirrors 25A and 25B in the wavelength conversion laser beams generated from the nonlinear optical crystals 1A and 1B is approximately the same. This is a wavelength conversion laser beam 3D.
The circularly polarized wavelength conversion laser beam 3D becomes a wavelength conversion laser beam 3G whose power is adjusted by the variable attenuator 24, is reflected by the reflection mirror 12, and is condensed and irradiated on the workpiece 17 by the condensing optical system 14. The workpiece is subjected to processing such as annealing, surface modification, drilling, cutting, welding, and trimming.

  As described above, in the present embodiment, the quarter wavelength plate 19 is provided as a means for combining the circular polarization means and the polarization state conversion means, and the wavelength conversion laser beam 3C is converted into circular polarization. As in the third embodiment, since the circularly polarized wavelength conversion laser beam 3D is focused and irradiated on the workpiece 17, more uniform processing independent of the polarization direction can be stably performed. There is an effect.

  Further, a variable attenuator 24 is provided as means for adjusting the power of the wavelength conversion laser beam 3D, and is circularly polarized (the polarization state of the wavelength conversion laser beam 3C is converted to the respective wavelength conversions generated from the nonlinear optical crystals 1A and 1B). The wavelength-converted laser beam 3D (converted so that the ratio of the s-polarized component and the p-polarized component to the mirror surfaces of the variable transmittance mirrors 25A and 25B in the laser beam is approximately the same) is made incident on the variable attenuator 24. The power of the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3C and the power of the component generated from the wavelength conversion crystal 1B of the wavelength conversion laser beam 3C can be adjusted at the same rate. Therefore, the power can be adjusted with almost no change in the beam profile of the wavelength conversion laser beam 3G output from the wavelength conversion laser device. For this reason, the power can be adjusted with almost no change in the beam profile of the wavelength conversion laser beam 3G irradiated to the workpiece 17, and the processing can be performed by changing only the power as a processing parameter. Play.

  Furthermore, by reducing the transmittance of the variable attenuator 24 and placing a beam profiler at the processing point on the processing table 18A and measuring the beam profile at the processing point, it is possible to measure the beam profile that is approximately the same as that during processing. There is an effect.

  The polarization state of the wavelength conversion laser beam 3C as described above is changed into the s-polarization component and the p-polarization component with respect to the mirror surfaces of the variable transmittance mirrors 25A and 25B in the respective wavelength conversion laser beams generated from the nonlinear optical crystals 1A and 1B. The wavelength conversion laser beam 3D converted (circularly polarized) so that the ratio thereof is approximately the same is incident on the variable attenuator 24, and the power of the wavelength conversion laser beam 3G is converted to the wavelength of the variable transmittance mirrors 25A and 25B. The effect obtained by adjusting by changing the incident angle of the laser beam 3D is a unique effect obtained only in the wavelength conversion laser beam in which a plurality of linearly polarized light components are mixed as in the present invention. This effect cannot be obtained with a general linearly polarized laser beam or a randomly polarized laser beam. . Hereinafter, this point will be described in detail.

  First, as a comparative example, a case where the quarter wavelength plate 19 is not provided and the wavelength conversion laser beam 3C that is not circularly polarized is incident on the variable attenuator 24 will be described. For example, when wavelength conversion laser beams having polarization directions different from each other by about 90 ° are generated from the wavelength conversion crystals 1A and 1B, the components generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3C are converted into s-polarized and wavelength conversion lasers. If the component generated from the wavelength conversion crystal 1B of the beam 3C is incident on the variable transmittance mirrors 25A and 25B as p-polarized light, the transmittance of the s-polarized light becomes lower than the transmittance of the p-polarized light. Among them, a wavelength conversion laser beam containing more components generated from the wavelength conversion crystal 1B than components generated from the wavelength conversion crystal 1A is output from the wavelength conversion laser device, and the workpiece 17 is irradiated with the wavelength conversion laser beam. Will be.

  Further, since the ratio of the transmittance between the s-polarized light and the p-polarized light varies depending on the transmittance of the variable attenuator 24 (variable transmittance mirrors 25A and 25B), only the power is adjusted by the variable attenuator 24 without changing the beam profile. For example, when the beam profiler is arranged at the processing point by reducing the transmittance of the variable attenuator 24 and the beam profile of the processing point is measured, the wavelength of the wavelength conversion laser beam 3C output from the wavelength conversion laser device The ratio of the component generated from the conversion crystal 1A and the component generated from the wavelength conversion crystal 1B is different at the time of processing and at the time of measuring the beam profile, and the beam profile at a processing point different from that at the time of processing is measured. .

  Specifically, for example, when processing with the average transmittance of the variable attenuator 24 lowered to about 50%, the transmittance of the s-polarized light of the variable transmittance mirrors 25A, 25B is, for example, about 35%, and the variable transmittance mirror 25A, The transmittance of 25B p-polarized light is about 65%, for example, the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3C is about 35%, and the component generated from the wavelength conversion crystal 1B of the wavelength conversion laser beam 3C is about 65%. % Wavelength conversion laser beam, that is, a wavelength conversion laser beam having a ratio of a component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3C to a component generated from the wavelength conversion crystal 1B is approximately 1: 1.9. A wavelength-converted laser beam output from the laser device and having a different ratio between the component generated from the wavelength conversion crystal 1A and the component generated from the wavelength conversion crystal 1B It will be processed.

  Further, for example, when the transmittance of the variable attenuator 24 is lowered to about 1% and a beam profiler is arranged at a processing point on the processing table 18A and the beam profile of the processing point is measured, the s of the variable transmittance mirrors 25A and 25B is measured. The transmittance of the polarized light is about 0.1%, for example, and the transmittance of the p-polarized light of the variable transmittance mirrors 25A and 25B is about 0.9%, for example, and the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3C is about A wavelength conversion laser beam containing about 0.9% of a component generated from the wavelength conversion crystal 1B of the wavelength conversion laser beam 3C, that is, a component to wavelength generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3C. The ratio of the components generated from the conversion crystal 1B is approximately 1: 9, and the wavelength conversion laser beam is emitted from the wavelength conversion laser device at a rate completely different from that at the time of processing. For example, when the above-mentioned variable attenuator 24 is processed at an average transmittance of about 50%, the ratio of the component generated from the wavelength conversion crystal 1A and the ratio of the component generated from the wavelength conversion crystal 1B are different. The beam profile will be measured. Therefore, there is a problem that the beam profile at the time of machining is different from that at the time of measuring the beam profile, the beam profile at the time of machining cannot be accurately grasped, and the influence of the beam profile on the machining cannot be accurately grasped.

However, in the present embodiment, the light is circularly polarized by the quarter wavelength plate 19 (the polarization state of the wavelength conversion laser beam 3C is variable in each wavelength conversion laser beam generated from each nonlinear optical crystal 1A, 1B. Since the wavelength-converted laser beam 3D (converted so that the ratio of the s-polarized component and the p-polarized component with respect to the mirror surfaces of the transmittance mirrors 25A and 25B is approximately the same) is made incident on the variable attenuator 24. The components of the converted laser beam 3D generated from the wavelength conversion crystal 1A and the components generated from the wavelength conversion crystal 1B are approximately equal in the ratio of the s-polarized component and the p-polarized component incident on the variable transmittance mirrors 25A and 25B. The component generated from the wavelength conversion crystal 1A of the beam 3D and the component generated from the wavelength conversion crystal 1B are approximately equal. The wavelength conversion laser beam including portions can be irradiated to the workpiece 17.
Further, even if the transmittance of the variable attenuator 24 is changed, the component generated from the wavelength conversion crystal 1A and the component generated from the wavelength conversion crystal 1B are included at approximately the same ratio, so that the beam profile is changed by the variable attenuator 24. Without adjusting the power alone. Therefore, for example, by reducing the transmittance of the variable attenuator 24 and arranging the beam profiler at the processing point and measuring the beam profile at the processing point, it is possible to measure approximately the same beam profile as during processing.

  Specifically, for example, when processing with the average transmittance of the variable attenuator 24 lowered to about 50%, the transmittance of the s-polarized light of the variable transmittance mirrors 25A, 25B is, for example, about 35%, and the variable transmittance mirror 25A, The transmittance of p-polarized light of 25B is, for example, about 65%. Of the components generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D, the s-polarized component is about 50% and the p-polarized component is also about 50%. About 35% of the polarization component (about 17.5% of the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D) and about 65% of the p polarization component (generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D) The sum of the components (about 32.5%), that is, about 50% of the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D passes through the variable attenuator 24. Similarly, the component generated from the wavelength conversion crystal 1B of the wavelength conversion laser beam 3D is also about 50% of the s-polarized component and about 50% of the p-polarized component, and therefore from the wavelength conversion crystal 1B of the wavelength conversion laser beam 3D. About 50% of the generated components pass through the variable attenuator 24.

  Therefore, the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D and the component generated from the wavelength conversion crystal 1B of the wavelength conversion laser beam 3D are transmitted through the variable attenuator 24 by the same ratio, and the wavelength conversion of the wavelength conversion laser beam 3D is performed. The wavelength conversion laser beam 3G having a ratio of the component generated from the crystal 1A to the component generated from the wavelength conversion crystal 1B of approximately 1: 1 is emitted from the wavelength conversion laser device, and the component generated from the wavelength conversion crystal 1A versus the wavelength conversion crystal 1B Then, processing is performed with the wavelength conversion laser beam 3G having a ratio of components generated from 1 to 1 of approximately 1: 1.

  Further, for example, when the beam profiler is arranged at the processing point by reducing the transmittance of the variable attenuator 24 to about 1% and the beam profile at the processing point is measured, the transmittance of the s-polarized light of the variable transmittance mirrors 25A and 25B. Is about 0.1%, and the transmittance of the p-polarized light of the variable transmittance mirrors 25A and 25B is about 0.9%, for example. Of the components generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D, the s-polarization component is Since about 50% and p-polarized component are also about 50%, about 0.1% of s-polarized component (about 0.05% of the component generated from wavelength conversion crystal 1A of wavelength-converted laser beam 3D) and p-polarized component Of about 0.9% (about 0.45% of the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D), that is, the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D About 0.5% passes through a variable attenuator 24. Similarly, the component generated from the wavelength conversion crystal 1B of the wavelength conversion laser beam 3D is also generated from the wavelength conversion crystal 1B of the wavelength conversion laser beam 3D because the s-polarization component is about 50% and the p-polarization component is about 50%. About 0.5% of the obtained components pass through the variable attenuator 24.

  Therefore, the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D and the component generated from the wavelength conversion crystal 1B of the wavelength conversion laser beam 3D are transmitted through the variable attenuator 24 by the same ratio, and the wavelength conversion of the wavelength conversion laser beam 3D is performed. The wavelength conversion laser beam 3G having a ratio of the component generated from the crystal 1A to the component generated from the wavelength conversion crystal 1B of approximately 1: 1 is emitted from the wavelength conversion laser device, and the component generated from the wavelength conversion crystal 1A versus the wavelength conversion crystal 1B The beam profile of the processing point can be measured with the wavelength conversion laser beam 3G having a ratio of components generated from 1 to approximately 1: 1.

  Accordingly, since the ratio of the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D to the component generated from the wavelength conversion crystal 1B at the time of processing and measurement of the beam profile is approximately the same, the beam profile at the time of processing is almost the same. It is possible to accurately grasp the influence of the beam profile on the machining, and it is possible to change the machining conditions by looking at the measured beam profile of the machining point.

On the other hand, in a general linearly polarized laser beam, since the polarization direction of the laser beam incident on the variable transmittance mirrors 25A and 25B is only one of s-polarized light and p-polarized light, the variable transmittance mirrors 25A and 25B. The transmittance is constant regardless of whether or not it is circularly polarized before being incident on. Therefore, there is no new effect caused by causing the circularly polarized wavelength conversion laser beam to enter the variable transmittance mirrors 25A and 25B.
Further, in a general randomly polarized laser beam, the polarization direction of the laser beam incident on the variable transmittance mirrors 25A and 25B is the same ratio of s-polarized light and p-polarized light. The transmittance is constant regardless of whether or not it is circularly polarized before being incident. Therefore, there is no new effect caused by causing the circularly polarized wavelength conversion laser beam to enter the variable transmittance mirrors 25A and 25B.

In the above description, the wavelength conversion laser beams whose polarization directions are different from each other by about 90 ° are generated from the wavelength conversion crystals 1A and 1B, but specific numerical values are given. The same can be said for different cases in the range of 90 °. For example, the wavelength conversion laser beam 3C is passed through a quarter-wave plate 19 which is also a means that also serves as a polarization state conversion means, and of the components generated from the wavelength conversion crystal 1A, the s-polarized component is about 60% and the p-polarized component. Is approximately 40%, of the components generated from the wavelength conversion crystal 1B, the s-polarized component is approximately 60%, the p-polarized component is approximately 40%, and so on. In the wavelength conversion laser beam 3D, the component generated from the wavelength conversion crystal 1A is converted into the wavelength conversion laser beam 3D converted into elliptically polarized light in which the ratio of the s-polarized component and the p-polarized component is approximately the same. Components generated from the wavelength conversion crystal 1B are incident on the variable attenuator 24 at the same rate. Thus, the ratio of the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D during processing and the measurement of the beam profile to the component generated from the wavelength conversion crystal 1B is approximately the same. Can be grasped almost accurately, the influence of the beam profile on the machining can be grasped almost accurately, and the machining conditions can be changed by looking at the measured beam profile of the machining point.

  8 shows the case where the wavelength conversion laser device includes the quarter wavelength plate 19 and the variable attenuator 24. Further, after the variable attenuator 24, as in the fourth embodiment, the quarter wavelength plate. 19, a reflection mirror 21, 21A, and a means for monitoring beam parameters such as a power monitor 22 and a beam profiler 23. The wavelength conversion laser having the same effects as in the fourth embodiment and having the power adjusted. The power and beam profile of the beam 3G can be monitored almost accurately.

  8 shows the case where the wavelength conversion laser device according to the first embodiment includes the quarter wavelength plate 19 and the variable attenuator 24. However, the laser processing device according to the second embodiment includes the quarter wavelength plate. 19 and the variable attenuator 24 may be provided, and the same effect can be obtained.

  Further, FIG. 8 shows the case where the variable attenuator 24 having a variable transmittance is provided. However, an attenuator having a constant transmittance may be provided. In this case, the wavelength conversion crystal 1A of the wavelength conversion laser beam 3C may be provided. The power of the generated component and the power of the component generated from the wavelength conversion crystal 1B of the wavelength conversion laser beam 3C can be adjusted at the same rate. Therefore, there is an effect that the power can be adjusted by an attenuator having a constant transmittance, while hardly changing the beam profile of the wavelength conversion laser beam 3G output from the wavelength conversion laser device. For this reason, it is possible to adjust the power corresponding to the transmittance of the attenuator with almost no change in the beam profile of the wavelength-converted laser beam 3G irradiated to the workpiece 17, and processing by changing only the power as a processing parameter. There is an effect that can be done.

  In the fourth and fifth embodiments, the polarization state conversion means such as the quarter wavelength plate 19 changes the polarization state of the wavelength conversion laser beam to the respective wavelength conversion laser beams generated from the respective nonlinear optical crystals 1A and 1B. Is preferably converted so that the ratio of the s-polarized component and the p-polarized component with respect to the reflecting surface of the reflecting means (the mirror surface of the variable transmittance mirror) is exactly the same, but the wavelength conversion generated from the nonlinear optical crystal 1A If the ratio of the value of the s-polarized component / p-polarized component of the laser beam to the value of the s-polarized component / p-polarized component of the wavelength-converted laser beam generated from the nonlinear optical crystal 1B is approximately between 1: 4 and 4: 1. It often has the same effect.

  Specifically, for example, the wavelength conversion laser beam generated from the nonlinear optical crystal 1A has an s-polarized component of about 20% and a p-polarized component of about 80%, and the s-polarized light of the wavelength converted laser beam generated from the nonlinear optical crystal 1B. When the component is about 50% and the p-polarized component is about 50%, the value of the s-polarized component / p-polarized component of the wavelength-converted laser beam generated from the nonlinear optical crystal 1A and the wavelength-converted laser beam generated from the nonlinear optical crystal 1B The ratio of the s-polarized component / p-polarized component value is 1: 4. In this case, when processing with the average transmittance of the variable attenuator 24 lowered to about 50%, the transmittance of the s-polarized light of the variable transmittance mirrors 25A and 25B is, for example, about 35%, and the p-polarized light of the variable transmittance mirrors 25A and 25B. Is approximately 65%, for example, of the components generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D, the s-polarized component is approximately 20% and the p-polarized component is approximately 80%. 35% of the s-polarized component (about 7% of the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D) and about 65% of the p-polarized component (wavelength conversion laser) About 52% of the component generated from the wavelength conversion crystal 1A of the beam 3D), that is, about 59% of the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D is variable. It is transmitted through the Teneta 24. Since the component generated from the wavelength conversion crystal 1B of the wavelength conversion laser beam 3D is also about 50% of the s-polarized component and about 50% of the p-polarized component, as described above, the wavelength conversion crystal 1B of the wavelength conversion laser beam 3D. About 50% of the components generated from the gas pass through the variable attenuator 24.

  Therefore, the wavelength conversion laser beam 3G having a ratio of the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D to the component generated from the wavelength conversion crystal 1B is approximately 1.18: 1 is emitted from the wavelength conversion laser device, Processing is performed with the wavelength conversion laser beam 3G in which the ratio of the component generated from the conversion crystal 1A to the component generated from the wavelength conversion crystal 1B is approximately 1.18: 1.

  Further, for example, when the beam profiler is arranged at the processing point by reducing the transmittance of the variable attenuator 24 to about 1% and the beam profile at the processing point is measured, the transmittance of the s-polarized light of the variable transmittance mirrors 25A and 25B. Is about 0.1%, and the transmittance of the p-polarized light of the variable transmittance mirrors 25A and 25B is about 0.9%, for example. Of the components generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D, the s-polarization component is Since the p-polarized component is about 20% and about 80%, about 0.1% of the s-polarized component (about 0.02% of the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D) and the p-polarized component Of about 0.9% (about 0.72% of the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D), that is, the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D About 0.8% passes through a variable attenuator 24. Of the components generated from the wavelength conversion crystal 1B of the wavelength conversion laser beam 3D, the s-polarized component is about 50% and the p-polarized component is about 50%, so that the wavelength conversion crystal 1B of the wavelength conversion laser beam 3D is as described above. About 0.5% of the component generated from the light passes through the variable attenuator 24.

  Therefore, the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D and the component generated from the wavelength conversion crystal 1B of the wavelength conversion laser beam 3D are transmitted through the variable attenuator 24 by the same ratio, and the wavelength conversion of the wavelength conversion laser beam 3D is performed. A wavelength conversion laser beam 3G having a ratio of the component generated from the crystal 1A to the component generated from the wavelength conversion crystal 1B of approximately 1.6: 1 is emitted from the wavelength conversion laser device, and the component generated from the wavelength conversion crystal 1A is converted to wavelength. The beam profile of the processing point can be measured with the wavelength conversion laser beam 3G having a ratio of components generated from the crystal 1B of approximately 1.6: 1.

  Therefore, the difference between the component generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3D at the time of processing and the measurement of the beam profile / the value of the component generated from the wavelength conversion crystal 1B is approximately 36%. The profile can be grasped approximately accurately, the influence of the beam profile on the machining can be grasped approximately accurately, and the processing conditions can be changed by looking at the measured beam profile of the processing point.

  In the fourth and fifth embodiments, the polarization state of the wavelength conversion laser beam is determined by reflecting the reflection means (reflection mirrors 21 and 21A) of the respective wavelength conversion laser beams generated from the nonlinear optical crystals 1A and 1B. Or the case where the quarter wave plate 19 was used as the polarization state conversion means for converting the ratio of the s-polarized component and the p-polarized component to the mirror surfaces of the variable transmittance mirrors 25A and 25B to be approximately the same has been described. However, it is not limited to this. As the polarization state conversion means, for example, an electro-optical element that converts a wavelength-converted laser beam into circularly polarized light may be used. Further, as the polarization state conversion means, for example, a half-wave plate, a polarization rotator, an electro-optic element, etc. are used to rotate the polarization direction of the wavelength conversion laser beam 3C, and the wavelength conversion laser beam 3C is generated from the wavelength conversion crystal 1A. The ratio of the s-polarized component and the p-polarized component with respect to the reflecting surface (mirror surface) of each mirror in the obtained component, and the s-polarized component with respect to the reflecting surface (mirror surface) of each mirror in the component generated from the wavelength conversion crystal 1B The ratio of the p-polarized component may be approximately the same, and the same effects as in the fourth and fifth embodiments are achieved.

  In the fourth and fifth embodiments, for example, wavelength conversion laser beams whose polarization directions are different from each other by about 90 ° are generated from the wavelength conversion crystals 1A and 1B, and generated from the wavelength conversion crystal 1A of the wavelength conversion laser beam 3C. In the configuration in which the component generated from the wavelength conversion crystal 1B of the wavelength conversion laser beam 3C is incident on the reflection mirrors 21 and 21A (variable transmittance mirrors 25A and 25B) as p-polarization, the nonlinear optical crystals 1A and 1B When the separation mirror 6 is arranged by rotating, for example, 45 ° around the optical axis of the laser beam 3, the reflection mirrors 21 and 21A in the respective wavelength conversion laser beams generated from the respective nonlinear optical crystals 1A and 1B are arranged. Since the ratio of the s-polarized component and the p-polarized component with respect to the reflecting surface is approximately the same, there is no polarization state conversion means. You may leave. However, in this case as well, by providing circular polarization means such as the quarter wavelength plate 19, the circularly polarized wavelength conversion laser beam is applied to the workpiece 17 as described in the third embodiment. Since it is focused and irradiated, it is possible to stably carry out more uniform processing independent of the polarization direction.

In each of the above-described embodiments, the case where an Nd: YAG (neodymium / yag) laser that generates a randomly polarized fundamental wave laser beam 3 with a wavelength of 1064 nm is used as the laser light source 2 has been described. The type is not limited to this, and for example, a solid-state laser such as an Nd: YLF (Neodymium / Ilf) laser, an Nd: YVO ₄ (Neodymium / Wi-Fi) laser, a Ti: Al ₂ O ₃ (Titanium / Sapphire) laser, or the like. In addition, a gas laser such as an argon laser or an excimer laser, a liquid laser such as a dye laser, or the like may be used. However, as in the case of an Nd: YVO ₄ (Neodymium Wi-Fi) laser, in general, it may oscillate linearly and may not be randomly polarized. However, for example, the cutting direction of a solid laser medium is a general direction. Random polarization can be obtained by setting the directions differently.

  In each of the above embodiments, the case where the nonlinear optical crystal that generates the second harmonic by the type 2 phase matching is used as the wavelength conversion crystals 1A and 1B. However, the fundamental laser beam 3 of random polarization is used. Since it is used, the type of phase matching may be type 1, and the same effects as those of the above embodiments can be obtained.

In each of the above embodiments, as the wavelength conversion crystals 1A and 1B, lithium borate (chemical formula: LiB ₃ O ₅ ) crystal that generates the second harmonic by type 2 phase matching is shown. The generated wavelength conversion laser beam is not limited to the second harmonic, and may be, for example, the third harmonic, the fourth harmonic, the fifth harmonic, the sum frequency, the difference frequency, and the like. The same effect as the form can be obtained.
Further, the nonlinear optical crystals for wavelength conversion (wavelength conversion crystals) 1A and 1B are not limited to the lithium borate (chemical formula: LiB ₃ O ₅ ) crystal, for example, cesium lithium borate (chemical formula: CsLiB ₆ O _10). , Abbreviation: CLBO) crystal, cesium borate (chemical formula: CsB ₃ O ₅ , abbreviation: CBO) crystal, beta barium borate (chemical formula: β-BaB ₂ O ₄ , abbreviation: BBO), gadolinium yttrium calcium, It may be an oxyborate (chemical formula: Gd _x Y _1-x Ca ₄ (BO ₃ ) ₃ , abbreviation: GdYCOB) crystal, potassium titanyl phosphate (chemical formula: KTiOPO ₄ , abbreviation: KTP) crystal, etc. The same effect as in each embodiment can be obtained.

In each of the above embodiments, the case where the same kind of crystal is used as the wavelength conversion crystal 1A, 1B has been described. For example, a lithium borate (chemical formula: LiB ₃ O ₅ ) crystal is used as the wavelength conversion crystal 1A. Different crystals such as cesium lithium borate (chemical formula: CsLiB ₆ O ₁₀ , abbreviation: CLBO) crystal may be used in combination as the wavelength conversion crystal 1B. In this case, the wavelength conversion generated in the wavelength conversion crystal 1A More specifically, the wavelength conversion crystal so that the polarization direction of the laser beam and the polarization direction of the wavelength conversion laser beam generated in the wavelength conversion crystal 1B are different from each other in a range of 45 ° to 90 ° (preferably about 90 °). The polarization direction of the wavelength conversion laser beam generated at 1A and incident on the wavelength conversion crystal 1B, and the wavelength generated at the wavelength conversion crystal 1B The polarization directions of the laser beams are different from each other in the range of 45 ° to 90 ° (preferably about 90 °) (in other words, the directions of polarization of the laser beams are in the range of 45 ° to 90 ° to each other (preferably about 90 °). The wavelength conversion crystals 1A and 1B may be arranged so as to generate different wavelength conversion laser beams, and the same effects as those of the above embodiments can be obtained.
Furthermore, by using a crystal having a wavelength conversion efficiency better than that of the wavelength conversion crystal 1A as the wavelength conversion crystal 1B, even if the lengths of the nonlinear optical crystals 1A and 1B in the laser beam passing direction are the same, the previous wavelength conversion The power of the wavelength conversion laser beam generated from the crystal 1A and the power of the wavelength conversion laser beam generated from the subsequent wavelength conversion crystal 1B can be made close to each other, and the wavelength conversion laser beam 3C is brought into a nearly isotropic polarization state. The effect that it can be obtained.

  In each of the above-described embodiments, the wavelength conversion laser device has a configuration in which a condensing lens is not used. However, between the laser light source 2 and the wavelength conversion crystal 1A, between the wavelength conversion crystals 1A and 1B, or the like. A condenser lens may be arranged, and in addition to the same effects as those of the above embodiments, the diameter of the fundamental laser beam incident on the wavelength conversion crystals 1A and 1B can be adjusted. The power of the wavelength conversion laser beam generated from the crystal 1A and the power of the wavelength conversion laser beam generated from the subsequent wavelength conversion crystal 1B can be made closer to each other, and the wavelength conversion laser beam 3C is polarized more nearly isotropically. The effect that it can be made is obtained.

  Further, in each of the above embodiments, the case where the condensing optical system 14 is disposed between the reflection mirror 12 and the processing table 18 (workpiece 17) in the irradiation device has been described. You may arrange | position also between the reflective mirrors 12. Further, for example, a beam homogenizing element such as a fly-eye lens or a mask that transmits only the central portion of the laser beam, for example, may be provided. In addition to the same effects as those of the above embodiments, more uniform processing can be stably performed. The effect that it can implement is acquired.

  In each of the above embodiments, as the wavelength conversion device, the fundamental wave laser beam travels in one direction and wavelength conversion is performed by the wavelength conversion nonlinear optical crystal (wavelength conversion crystals 1A, 1B), that is, the fundamental wave laser. Although the case of using a wavelength converting structure outside the resonator for generating the beam is shown, the present invention is not limited to this, and includes two nonlinear optical crystals for wavelength conversion arranged in series. If the wave laser beam is passed through two non-linear optical crystals and each of the non-linear optical crystals performs wavelength conversion so that the polarization directions are different from each other in the range of 45 ° to 90 ° (preferably about 90 °). Any configuration of the wavelength conversion device may be used.

It is a figure for demonstrating the laser processing method and laser processing apparatus by Embodiment 1 of this invention. It is a figure for demonstrating the laser processing method and laser processing apparatus by Embodiment 1 of this invention. It is a figure for demonstrating the laser processing method and laser processing apparatus by Embodiment 2 of this invention. It is a figure for demonstrating the laser processing method and laser processing apparatus by Embodiment 2 of this invention. It is a figure for demonstrating the laser processing method and laser processing apparatus by Embodiment 3 of this invention. It is a figure for demonstrating the laser processing method and laser processing apparatus by Embodiment 3 of this invention. It is a figure for demonstrating the laser processing method and laser processing apparatus by Embodiment 4 of this invention. It is a figure for demonstrating the laser processing method and laser processing apparatus by Embodiment 5 of this invention.

Explanation of symbols

  1A, 1B wavelength conversion crystal, 2 laser light source, 3 fundamental wave laser beam, 3A, 3B fundamental wave / harmonic mixed laser beam, 3C wavelength conversion (harmonic) laser beam, 6 separation mirror, 9A, 9B crystal orientation axis b , C surface, 10 1/2 wavelength plate, 12, 21, 21A reflecting mirror, 14 condensing optical system, 17 workpiece, 18, 18A processing table, 19 1/4 wavelength plate, 22 power monitor, 23 Beam profiler, 24 variable attenuator, 25A, 25B variable transmittance mirror, a, b, c crystal orientation axis.

Claims (16)

The fundamental laser beam is passed through two nonlinear optical crystals for wavelength conversion arranged in series, and the two nonlinear optical crystals are wavelength-converted so that their polarization directions are different from each other in the range of 45 ° to 90 °. A laser processing method comprising irradiating a workpiece with a wavelength-converted laser beam. 2. The laser processing method according to claim 1, wherein the workpiece is irradiated with a wavelength-converted laser beam that has been wavelength-converted so that the polarization directions are different from each other by approximately 90 °. 2. The laser processing method according to claim 1, wherein the workpiece is irradiated with a wavelength-converted laser beam converted into circularly polarized light. The polarization state of the wavelength conversion laser beam is converted so that the ratio of the s-polarized component and the p-polarized component with respect to the incident target surface in each wavelength-converted laser beam generated from each nonlinear optical crystal is approximately the same, and the polarization state is changed. The converted wavelength conversion laser beam is incident on a reflection means that transmits a part of the laser beam, and one of the wavelength conversion laser beam transmitted through the reflection means and the wavelength parameter of the wavelength conversion laser beam reflected by the reflection means is monitored. The laser processing method according to claim 1, wherein the workpiece is irradiated with the other. 5. The laser processing method according to claim 4, wherein the beam parameter to be monitored is a power or a beam profile. The polarization state of the wavelength conversion laser beam is converted so that the ratio of the s-polarized component and the p-polarized component with respect to the incident target surface in each wavelength-converted laser beam generated from each nonlinear optical crystal is approximately the same, and the polarization state is changed. 2. The laser processing method according to claim 1, wherein the converted wavelength conversion laser beam is incident on a variable attenuator, the power is adjusted, and the workpiece is irradiated. A laser light source for generating a fundamental wave laser beam and two nonlinear optical crystals for wavelength conversion arranged in series are passed through the two nonlinear optical crystals and polarized by the respective nonlinear optical crystals. A wavelength conversion device that converts wavelengths so that directions are different from each other in a range of 45 ° to 90 °, and an irradiation device that irradiates a workpiece with a wavelength-converted laser beam wavelength-converted by the wavelength conversion device. A laser processing apparatus characterized by that. 8. The laser processing apparatus according to claim 7, wherein the wavelength conversion apparatus converts the wavelength of the fundamental laser beam so that the polarization directions thereof are different from each other by approximately 90 degrees. 8. The laser processing apparatus according to claim 7, further comprising circular polarization means for converting the wavelength conversion laser beam into circularly polarized light. Reflecting means that transmits a part of the wavelength conversion laser beam, means for monitoring one of the wavelength conversion laser beam transmitted through the reflection means and the wavelength conversion laser beam reflected by the reflection means, and the reflection means The ratio of the s-polarized component and the p-polarized component with respect to the reflecting surface of the reflecting means in each wavelength-converted laser beam generated from each nonlinear optical crystal is approximately the same. The laser processing apparatus according to claim 7, further comprising: a polarization state conversion unit that converts the light in the manner described above. The laser processing apparatus according to claim 10, wherein the beam parameter to be monitored is a power or a beam profile. A variable attenuator having a variable transmittance mirror, and a polarization state of the wavelength conversion laser beam disposed in front of the variable attenuator with respect to the mirror surface of the variable transmittance mirror in each wavelength conversion laser beam generated from each nonlinear optical crystal 8. The laser processing apparatus according to claim 7, further comprising polarization state conversion means for converting the ratio of the s-polarized component and the p-polarized component so as to be approximately the same. 8. The wavelength converter according to claim 7, wherein the crystal orientation axes of the two nonlinear optical crystals are arranged so as to be rotated within a range of 45 ° to 90 ° with respect to the optical axis direction of the laser beam. Laser processing equipment. 14. The laser processing apparatus according to claim 13, wherein the wavelength conversion device is arranged such that the crystal orientation axes of the two nonlinear optical crystals are rotated by approximately 90 ° from each other when viewed from the optical axis direction of the laser beam. In the wavelength conversion device, the crystal orientation axes of the two nonlinear optical crystals are arranged in the same direction or in a direction different by about 180 ° when viewed from the optical axis direction of the laser beam, and wavelength conversion is performed between the two nonlinear optical crystals. 8. The laser processing apparatus according to claim 7, further comprising polarization direction rotating means for rotating the polarization direction of the laser beam in a range of 45 ° to 90 °. 16. The laser processing apparatus according to claim 15, wherein the polarization direction rotating means rotates the polarization direction of the wavelength-converted laser beam by approximately 90 degrees.

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