JP2004220051A - Wavelength conversion method, wavelength conversion device, and laser working machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a wavelength conversion method by which light whose wavelength is converted by a nonlinear optical crystal can be stably generated for a long period of time, to provide a wavelength conversion device, and to provide a laser working machine using the same. <P>SOLUTION: In the wavelength conversion method, wavelength conversion is performed by making an atmosphere in contact with the surface of the nonlinear optical crystal from which light whose wavelength is converted is emitted a gas having the nitrogen content lower than that of air. The wavelength conversion device is provided with a means for making the atmosphere in contact with the surface of the nonlinear optical crystal from which light whose wavelength is converted is emitted the gas having the nitrogen content lower than that of air. The laser working machine is provided with the wavelength conversion device. Light whose wavelength is converted by the nonlinear optical crystal can stably be generated for a long period of time. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a wavelength conversion technique using a nonlinear optical crystal.

FIG. 12 is a cross-sectional view showing a conventional wavelength converter disclosed in Patent Document 1, for example. In Figure 12, 1 denotes a vacuum vessel, 2 is for example the cesium-lithium-borate (Formula: CsLiB ₆ 0 _10, abbreviated: CLBO) nonlinear optical crystal of a crystal such as, 3a, 3b is the optical window, 4a, 4b, 4c is O-ring, 5 is a vacuum sealing valve, and 6 is a fixture. Reference numeral 7 denotes the entire wavelength converter.

  Next, the operation will be described. The laser beam enters the vacuum vessel 1 from the input side optical window 3a, interacts with the nonlinear optical crystal 2, undergoes wavelength conversion, and then exits from the output side optical window 3b. A vacuum sealing valve 5 is provided on the upper portion of the vacuum vessel 1, and the space between the main body of the vacuum vessel 1 and the optical windows 3 a, 3 b and the vacuum sealing valve 5 is sealed by O-rings 4 a, 4 b, 4 c. The inside of the vacuum vessel 1 is maintained at a vacuum.

  Inside the vacuum vessel 1, the nonlinear optical crystal 2 is pressed from above by a fixture 6 and is fixed to the bottom of the vacuum vessel 1.

JP-A-11-271820

  As described above, in the conventional wavelength conversion device, since the atmosphere around the wavelength conversion crystal is maintained in a vacuum, impurities are easily generated from a vacuum container, an O-ring, a fixture, and the like that are exposed to the vacuum, and the impurities are non-linear. Since the optical crystal 2 (wavelength conversion crystal) adheres to the optical window, a wavelength-converted laser beam (that is, light whose wavelength has been converted by the nonlinear optical crystal) cannot be generated stably for a long period of time. This is necessary, and there is a problem that the apparatus becomes expensive.

  The present invention has been made in order to solve the above problems, and a wavelength conversion method and a wavelength conversion device capable of stably generating light whose wavelength has been converted by a nonlinear optical crystal for a long period of time, and a method thereof. It is an object of the present invention to provide a wavelength conversion laser device and a laser processing machine using the same.

  The wavelength conversion method according to the present invention is the wavelength conversion method of passing light through a nonlinear optical crystal, wherein the atmosphere in contact with an emission end face of the nonlinear optical crystal that emits the wavelength-converted light has a nitrogen element content. Is converted into a gas smaller than air and wavelength-converted.

  According to this, it is possible to obtain an effect that light whose wavelength has been converted by the nonlinear optical crystal can be stably generated for a long period of time.

  In addition, the wavelength conversion is performed by covering the incident end face of the nonlinear optical crystal on which the wavelength-converted light is incident and the emission end face from which the wavelength-converted light is emitted with a gas having a nitrogen element content smaller than that of air.

  According to this, it is possible to obtain the effect that the light whose wavelength has been converted by the nonlinear optical crystal can be generated more reliably and stably for a long period of time.

  Further, an atmosphere in contact with the incident end face of the nonlinear optical crystal where the wavelength-converted light is incident and an atmosphere in contact with the emission end face from which the wavelength-converted light exits are converted into gases of different components to perform wavelength conversion.

  According to this, the interaction between the nonlinear optical crystal and the atmosphere caused by the wavelength-converted light and the interaction between the nonlinear optical crystal and the atmosphere caused by the wavelength-converted light can be individually and efficiently prevented. The effect that can be obtained is obtained.

  In addition, a gas in which the content of the nitrogen element is smaller than that of air is passed.

  According to this, even if impurities are generated, the impurities are exhausted together with the flowing gas, so that the effect of preventing the impurities from adhering to the nonlinear optical crystal or the optical window can be obtained.

  In addition, a gas having a nitrogen content lower than that of air is supplied to at least the vicinity of the emission end face of the nonlinear optical crystal and then discharged.

  According to this, even if an impurity is generated, a fresh gas is supplied to the vicinity of the nonlinear optical crystal, so that the effect of reliably preventing the impurity from adhering to the nonlinear optical crystal can be obtained. Can be

  Further, the gas having a nitrogen element content lower than that of air is a gas having a nitrogen element gas having a volume content of 10% or less.

  According to this, it is possible to obtain an effect that light whose wavelength has been converted by the nonlinear optical crystal can be stably generated for a long period with a simple configuration.

  Further, the nonlinear optical crystal is a crystal containing cesium. According to this, it is possible to obtain an effect that high-output light in the ultraviolet region converted by the nonlinear optical crystal can be generated stably for a long period of time.

  Further, the gas is a gas mainly containing any of a rare gas, an oxygen gas, and a carbon dioxide gas.

  According to this, it is possible to obtain an effect that light whose wavelength has been converted by the nonlinear optical crystal can be stably generated for a long period with a simpler configuration.

  Further, the gas having a nitrogen element content lower than that of air, which is inferior to the surface of the nonlinear optical crystal 1 from which the wavelength-converted light is emitted, is a gas mainly composed of argon gas.

  According to this, it is possible to obtain the effect that the light whose wavelength has been converted by the nonlinear optical crystal can be generated more reliably and stably for a long period of time.

  The wavelength conversion device according to the present invention is a wavelength conversion device for converting light by passing light through a nonlinear optical crystal, wherein the atmosphere in contact with the surface of the nonlinear optical crystal where the wavelength-converted light is emitted has a nitrogen element content. It is provided with means for making gas smaller than air.

  According to this, it is possible to obtain an effect that light whose wavelength has been converted by the nonlinear optical crystal can be stably generated for a long period of time.

  It also emits wavelength-converted light having an average power of 5 W or more.

  According to this, it is possible to obtain an effect that high-output light whose wavelength has been converted by the nonlinear optical crystal can be stably generated for a long period of time.

  Further, there is provided means for covering the nonlinear optical crystal with a gas having a nitrogen element content smaller than that of air.

  According to this, it is possible to obtain the effect that the light whose wavelength has been converted by the nonlinear optical crystal can be generated more reliably and stably for a long period of time.

  Further, there is provided means for setting the atmosphere in contact with the surface of the nonlinear optical crystal on which the wavelength-converted light is incident, and the atmosphere in contact with the surface on which the wavelength-converted light is emitted, with gases of different components.

  According to this, the interaction between the nonlinear optical crystal and the atmosphere caused by the wavelength-converted light and the interaction between the nonlinear optical crystal and the atmosphere caused by the wavelength-converted light can be individually and efficiently prevented. The effect that can be obtained is obtained.

  Further, a means for flowing a gas having a nitrogen element content lower than that of air is provided.

  According to this, even if impurities are generated, the impurities are exhausted together with the flowing gas, so that the effect of preventing the impurities from adhering to the nonlinear optical crystal or the optical window can be obtained.

  Further, a nonlinear optical crystal is arranged in a container provided with a window or an opening for partially passing incident light and output light, and a gas having a nitrogen element content smaller than that of air is provided in the container at least in the nonlinear optical crystal. Means for supplying the gas to the vicinity of the emission end face; and means for discharging the supplied gas from the container.

  According to this, even if an impurity is generated, a fresh gas is supplied to the vicinity of the nonlinear optical crystal, so that the effect of reliably preventing the impurity from adhering to the nonlinear optical crystal can be obtained. Can be

  Further, the gas having a nitrogen element content lower than that of air is a gas having a nitrogen element gas having a volume content of 10% or less.

  According to this, it is possible to obtain an effect that light whose wavelength has been converted by the nonlinear optical crystal can be stably generated for a long period with a simple configuration.

  Further, the nonlinear optical crystal is a crystal containing cesium.

  According to this, it is possible to obtain an effect that high-output light in the ultraviolet region converted in wavelength by the nonlinear optical crystal can be stably emitted for a long period of time.

  Further, the gas having a nitrogen element content lower than that of air is a gas mainly composed of a rare gas, an oxygen gas, or a carbon dioxide gas.

  According to this, it is possible to obtain an effect that light whose wavelength has been converted by the nonlinear optical crystal can be stably generated for a long period with a simpler configuration.

  Further, the gas having a nitrogen element content lower than that of air, which is an atmosphere in contact with the surface of the nonlinear optical crystal from which light is emitted, is a gas mainly composed of argon gas.

  According to this, it is possible to obtain the effect that the light whose wavelength has been converted by the nonlinear optical crystal can be generated more reliably and stably for a long period of time. The laser processing machine according to the present invention includes a processing machine, and as a processing light source, a laser device serving as a light source for wavelength conversion, and an atmosphere in contact with a surface of the nonlinear optical crystal from which the wavelength-converted light is emitted, containing a nitrogen element. A wavelength conversion device having means for converting the laser light from the laser device through the non-linear optical crystal into a gas having a rate smaller than that of air.

  According to this, it is possible to obtain an effect that uniform processing can be performed accurately and uniformly for a long time.

  In order to investigate the cause of deterioration in wavelength conversion characteristics using a CLBO crystal, the present inventors have developed a laser device that generates a second harmonic of a neodymium-yag (Nd: YAG) laser having a wavelength of 1064 nm, that is, a laser beam having a wavelength of 532 nm. Using a CLBO crystal as a light source, an ultraviolet laser beam having a wavelength of 266 nm, which is the fourth harmonic of an Nd: YAG laser, was continuously generated for 100 hours. During generation of this continuous ultraviolet laser beam, the CLBO crystal was placed on a heater in air and used at a constant temperature of 140 ° C. The average power of the generated ultraviolet laser beam having a wavelength of 266 nm was 20 W.

After the 100-hour continuous ultraviolet laser beam generation test, newly attached substances were observed on the ultraviolet laser beam emission end face of the CLBO crystal, that is, the face from which the wavelength-converted light was emitted. Elemental analysis and structural analysis of the paddy substance revealed that the adhered substance was a nitric acid compound containing cesium nitrate (CsNO ₃ ). This cesium nitrate is observed only at the UV laser beam emission end face of the CLBO crystal, and cesium is an element not contained in components other than the CLBO crystal used for wavelength conversion. It is clear that cesium, which is a component of the CLB * crystal, and nitrogen in the atmosphere caused a reaction of the ultraviolet laser beam to produce cesium nitrate. The generation of cesium nitrate by wavelength conversion using a CLBO crystal is a phenomenon first clarified by a long-term continuous ultraviolet laser beam generation test performed by the present inventors at an average power of 5 W or more. Conventionally, as shown in the literature (Kyoichi Nari, et al., Institute of Electrical and Optical Quantum Devices of the Institute of Electrical Engineers, OQD-97, 53-69, pp. 41-46, 1997), an output of 4 W or less was used. This phenomenon had not been clarified because only a long-term operation test was performed.

  From the above results, when performing wavelength conversion using a CLBO crystal, the atmosphere in contact with the emission end face at which the wavelength-converted light of the nonlinear optical crystal emits is a gas having a lower nitrogen element content than air. If it is carried out in such a manner that the gas is desirably made to contain almost no nitrogen element (N), it is possible to stably perform high-power wavelength conversion for a long period of time as compared with the case where the atmosphere is air. Became clear.

  Example 1.

  1 and 2 are views for explaining a wavelength conversion method and a wavelength conversion device according to a first embodiment for carrying out the present invention. More specifically, FIG. FIG. 2 is a longitudinal sectional view, and FIG. 2 is a transverse sectional view of the wavelength converter.

  1 and 2, reference numeral 2 denotes a nonlinear optical crystal. Reference numerals 3a and 3b denote optical windows that transmit the laser beam. 4a and 4b are O-rings. Reference numeral 11 denotes a container for storing the nonlinear optical crystal 2. 12a and 12b are optical window holders. 13a and 13b are holes formed in the container 11. 14a and 14b are stoppers. 15a and 15b are pipes. Numeral 16 denotes a gas containing no nitrogen element (N) or having a small amount of nitrogen element. 17a and 17b are fixing jigs for fixing the nonlinear optical crystal 2 to the container 11. 7a shows the whole wavelength converter.

  The non-linear optical crystal 2 is cut and polished at both ends to a phase matching angle for generating an ultraviolet laser beam having a wavelength of 400 nm or less by wavelength conversion, and is fixed on the container 11 by fixing jigs 17a and 17b. Here, the nonlinear optical crystal 2 is made of a CLBO crystal, and both end faces are cut and polished at a phase matching angle for converting a laser beam having a wavelength of 532 nm into an ultraviolet laser beam having a wavelength of 266 nm.

The optical windows 3a and 3b are made of, for example, quartz (chemical formula: SiO ₂ ) or calcium fluoride (chemical formula: CaF ₂ ) transparent to at least a laser beam having a wavelength of 200 nm to 1500 nm, and are polished at both ends, and are O-rings. It is in close contact with the container 11 by optical window holders 12a and 12b via 4a and 4b. The plugs 14a and 14b used here are directly joined to the container 11 by PT screws (tapered screws for pipes). The container 11 is kept airtight by optical windows 3a, 3b, O-rings 4a, 4b and plugs 14a, 14b.

  The laser beam enters the container 11 from the input side optical window 3a, is wavelength-converted by the nonlinear optical crystal 2, and is emitted from the output side optical window 3b.

The gas 16 does not contain a nitrogen element (N) or has a low content of a nitrogen element. For example, a gas mainly composed of a rare gas, an oxygen gas (O ₂ ), a carbon dioxide gas (CO ₂ ), or the like may be used. It flows into the container 11 through a pipe 15a and a perforated plug 14a, and flows out of the container 11 through a perforated plug 14b and a pipe 15b. For this reason, the inside 11 of the container is filled with a gas 16 containing no nitrogen element or containing little nitrogen element.

  In the first embodiment, the wavelength conversion device 7a is configured as described above, and the incident end face of the nonlinear optical crystal 2 on which the wavelength-converted light is incident and the emission end face on which the wavelength-converted light exits have components. Since it is exposed to a gas 16 containing no nitrogen element or having a low nitrogen element, even if it is subjected to wavelength conversion of a laser beam and irradiated with an ultraviolet laser beam having a wavelength of 400 nm or less, a nitrate compound such as cesium nitrate can be used. Since no wavelength conversion laser beam is generated by the nitric acid compound and the output is not further reduced by the nitric acid compound, and since the inside of the wavelength conversion device 7a is not evacuated, impurities are removed from the container. Since it does not occur and impurities do not adhere to the nonlinear optical crystal 2 or the optical window, a high-quality and high-output wavelength conversion laser beam can be stably maintained for a long time. It achieves the effect rack that can be generated.

  In addition, the gas 16 flows into the container 11 and flows so as to always flow out of the container 11, and is flowing. Therefore, even if impurities are generated, the gas 16 is discharged together with the flowing gas 16. Therefore, there is an effect that impurities can be prevented from adhering to the nonlinear optical crystal 2 and the optical windows 3a and 3b.

  Further, the wavelength converter 7a does not need to be a strictly airtight container, and can generate a high-output wavelength-converted laser beam stably for a long time only by flowing a small amount of a rare gas, oxygen, carbon dioxide gas, or the like. Therefore, the wavelength converter can be provided at a low cost.

As the nonlinear optical crystal 2, a crystal containing cesium, such as a cesium lithium borate (chemical formula: CsLiB ₆ O ₁₀ , abbreviation: CLBO) crystal, a cesium borate (chemical formula: CsB ₃ O ₅ , abbreviation: CBO) crystal, etc. Is suitable, but lithium borate (chemical formula: LiB ₃ O ₅ , abbreviation: LBO) crystal, beta barium borate (chemical formula: β-BaB ₂ O ₄ , abbreviation: BBO), gadolinium yttrium calcium calcium oxy Even in a crystal containing no cesium, such as a borate (chemical formula: Gd _x Y _1-x Ca ₄ (BO ₃ ) ₃ , abbreviated to GdYCOB) crystal, an element other than cesium can react with nitrogen to form a nitrogen compound. It can be used because there is a possibility.

  Further, although the cylindrical shape is shown as an example of the container 11, the shape may be any shape, for example, a cube or a rectangular parallelepiped.

  Also, the plugs 14a and 14b are described as being directly joined to the container 11 by, for example, a PT screw or an O-ring, but other plugs provided in the middle of the piping can be used.

  Further, in the first embodiment, an example was described in which the stoppers 14a and 14b were opened and the gas 16 containing no nitrogen element or the gas 16 containing little nitrogen element was constantly flowed. After filling with less gas 16, the stoppers 14 a and 14 b may be closed to seal the gas 16 in the container 11, that is, a cell in which a nonlinear optical crystal is sealed may be used. Has the same effect as. However, in this case, the effect of flowing the gas 16 cannot be obtained.

  Embodiment 2.

  FIGS. 3 and 4 are views for explaining a wavelength conversion method and a wavelength conversion device according to a second embodiment for carrying out the present invention. More specifically, FIG. FIG. 4 is a longitudinal sectional view, and FIG. 4 is a transverse sectional view of the wavelength converter.

  In FIGS. 3 and 4, 2, 3a, 3b, 4a, 4b, 11, 12a, 12b, 13a, 13b, 14a, 14b, 15a, 15b, 16 are the same as those shown in the first embodiment. And have the same effect. 17 c and 17 d are fixing jigs for fixing the nonlinear optical crystal 2 on the heating element 18. Reference numeral 18 is a heating element provided with an electric heater. 19 is a heat insulating material. 7b shows the whole wavelength converter. Although not shown, a temperature sensor for monitoring the temperature is provided in the heating element 18, and the heating element 18 and the temperature sensor are connected to a temperature controller outside the wavelength conversion device 7b through an electric wire (not shown). It is connected to the.

  The heating element 18 is controlled by a temperature controller in accordance with a signal from a temperature sensor in accordance with a signal from a temperature sensor, and is controlled to a constant temperature exceeding 100 ° C. so that the fixing jigs 17 c and 17 d and the nonlinear optical crystal 2 are controlled. Is kept at a constant temperature of 100 ° C. or higher.

  The laser beam enters the container 11 from the input side optical window 3a, is wavelength-converted by the nonlinear optical crystal 2, and is emitted from the output side optical window 3b.

  In the second embodiment, the wavelength converter 7b is configured as described above, and the nonlinear optical crystal 2 is kept at a constant temperature of 100 ° C. or higher. As a result, even when the gas 16 contains a very small amount of moisture, the nonlinear optical crystal 2 does not absorb moisture, so that the wavelength conversion laser beam can be stably generated for a long period of time.

  As in the case of the first embodiment, the incident end face of the nonlinear optical crystal 2 on which the wavelength-converted light is incident and the exit end face on which the wavelength-converted light exits do not contain a nitrogen element or have a nitrogen element. Is exposed to the gas 16 having a small amount, and does not generate a nitrate compound such as cesium nitrate even if it is subjected to wavelength conversion of a laser beam and is irradiated with an ultraviolet laser beam having a wavelength of 400 nm or less. Since the inside of 7a is not evacuated, no impurities are generated from the container, so that there is an effect that a high-quality and high-output wavelength conversion laser beam can be stably generated for a long period of time. In addition, since the wavelength conversion unit 7b does not need to be a vacuum container, the wavelength conversion device can be provided at low cost.

  Further, even if impurities are generated, the impurities are exhausted together with the flowing gas 16, so that the effect of preventing the impurities from adhering to the nonlinear optical crystal 2 and the optical windows 3 a and 3 b can be obtained.

  Although the cylindrical shape of the container 11 is shown as an example, the shape may be any shape, for example, a cube or a rectangular parallelepiped.

  Also, the plugs 14a and 14b are described as being directly joined to the container 11 by, for example, a PT screw or an O-ring, but other plugs provided in the middle of the piping can be used.

  Further, an example in which an electric heater is provided as the heating element 18 has been described. However, the present invention is not limited to this. For example, a heating element such as a Peltier element may be provided.

  Further, in the second embodiment, the stoppers 14a and 14b are opened and the gas 16 containing no nitrogen element or the gas 16 containing little nitrogen element is always flowed. After filling with less gas 16, plugs 14 a and 14 b may be closed to seal gas 16 in container 11, and the same effect as in the second embodiment may be obtained. However, in this case, the effect of flowing the gas 16 cannot be obtained.

  Embodiment 3 FIG.

  FIG. 5 is a diagram for explaining a wavelength conversion method and a wavelength conversion device according to a third embodiment for carrying out the present invention, and more specifically, is a longitudinal sectional view of the wavelength conversion device.

  In FIG. 5, 2, 16, 17a, and 17b are the same as those shown in the first embodiment and have the same functions. 35 is a container main body, 36a and 36b are lids, and 37 is a container. Reference numerals 38a and 38b denote holes through which light formed in the lids 36a and 36b passes. 13c is a hole formed in the container body 35. 14c is a stopper. 15c is a pipe. 7c shows the whole wavelength converter.

  The container 37 is constituted by the container body 35 and the lids 36a and 36b, and the lid 36a and the lid 36b are provided with holes 38a and 38b through which light passes, respectively.

  A gas 16 containing a gas other than nitrogen as a main component, for example, a gas mainly composed of a rare gas, an oxygen gas, a carbon dioxide gas, or the like, flows into the container 37 from a hole 13c provided in the container body 35 through the plug 14c from the pipe 15c. Let it. The gas 16 replaces the air in the container 37 and fills the container 37 with the gas 16 and is discharged from the holes 38a and 38b.

  As described above, the container 37 does not necessarily need to be airtight, and the atmosphere of the nonlinear optical crystal 2 may be a gas containing no nitrogen element or a gas containing little nitrogen element. Further, at least the gas in contact with the surface of the nonlinear optical crystal 2 from which the wavelength-converted light 5 is emitted does not contain a nitrogen element or is a gas containing a small amount of nitrogen element, and the same effect as in the first embodiment can be obtained. . As in the case of the second embodiment, the heating element 18 and the heat insulating material 19 may be provided to keep the nonlinear optical crystal 2 at a constant temperature of 100 ° C. or higher.

  In the first to third embodiments, the atmosphere of the nonlinear optical crystal 2 does not contain a nitrogen element or is a gas containing a small amount of a nitrogen element. If so, high-output wavelength conversion can be performed stably for a long time as compared with the case where the atmosphere is air. However, the volume content of nitrogen is preferably 10% or less, and more preferably 1% or less. Therefore, the gas mainly composed of a rare gas, an oxygen gas, a carbon dioxide gas, or the like to be flowed or sealed in the container in which the nonlinear optical crystal 2 is arranged does not have to be a high-purity gas; it can. A gas mainly composed of a rare gas, an oxygen gas, a carbon dioxide gas, or the like preferably has a volume content of, for example, 50% or more, more preferably 90% or more, and even more preferably 99% or more.

  Embodiment 4. FIG.

  FIG. 6 is a diagram for explaining a wavelength conversion method and a wavelength conversion device according to a fourth embodiment for carrying out the present invention, and more specifically, is a longitudinal sectional view of the wavelength conversion device.

  In FIG. 6, 2, 3a, 3b, 4a, 4b, 11, 12a, 12b, 17c, 17d, 18, and 19 are the same as those shown in the first or second embodiment, and have the same functions. I do. 13a, 13b, 13c and 13d are holes made in the container 11. 14a, 14b, 14c and 14d are stoppers. 15a, 15b, 15c, and 15d are pipes. 16b is a gas which does not contain a nitrogen element (N) or has a small content of a nitrogen element. 16a is a gas composed of a component different from the gas 16b. 7d shows the whole wavelength converter. Although not explicitly shown in FIG. 6, the space in the container 11 that is in contact with the incident end face of the nonlinear optical crystal 2 where the wavelength-converted light is incident and the space that is in contact with the output end face where the wavelength-converted light is emitted. Are separated from each other by, for example, a partition.

  The non-linear optical crystal 2 is cut and polished at both ends to a phase matching angle for generating an ultraviolet laser beam having a wavelength of 400 nm or less by wavelength conversion, and is fixed on the container 11 by fixing jigs 17c and 17d. Here, the nonlinear optical crystal 2 is made of a CLBO crystal, and both end faces are cut and polished at a phase matching angle for converting a laser beam having a wavelength of 532 nm into an ultraviolet laser beam having a wavelength of 266 nm.

  The laser beam enters the container 11 from the optical window 3a on the input side, undergoes wavelength conversion by the nonlinear optical crystal 2, and then exits from the optical window 3b on the output side.

  The gas 16a enters the space in contact with the incident end face of the nonlinear optical crystal 2 in the container 11 from the pipe 15b through the plug 14b and the hole 13b, and sets the atmosphere in contact with the incident end face of the nonlinear optical crystal 2 to the atmosphere of the gas 16a. The liquid is discharged out of the container 11 through the plug 13a, the plug 14a, and the pipe 15a. The gas 16b enters the space in contact with the emission end face of the nonlinear optical crystal 2 in the container 11 from the pipe 15c through the plug 14c and the hole 13c, and sets the atmosphere in contact with the emission end face of the nonlinear optical crystal 2 to the atmosphere of the gas 16b. , Holes 13d, plugs 14d, and pipes 15d to be discharged out of the container 11.

  In the fourth embodiment, the wavelength conversion device 7d is configured as described above, and the emission end face of the nonlinear optical crystal 2 is exposed to the gas 16b containing no nitrogen element or containing little nitrogen element. Therefore, even if the wavelength conversion of the laser beam is performed and the emission end face of the nonlinear optical crystal 2 is irradiated with an ultraviolet laser beam having a wavelength of 400 nm or less, a nitric acid compound such as cesium nitrate is not generated. Since no distortion occurs in the wavelength-converted laser beam and the output does not decrease, there is an effect that a high-quality and high-output wavelength-converted laser beam can be stably generated for a long period of time.

  Further, since the atmosphere in contact with the incident end face and the atmosphere in contact with the output end face of the nonlinear optical crystal 2 are composed of the gas 16a and the gas 16b having different components, it is caused by the light to be wavelength-converted, that is, the incident laser beam which becomes the fundamental wave of the wavelength conversion. It is possible to effectively prevent the interaction between the nonlinear optical crystal 2 and the atmosphere and the interaction between the nonlinear optical crystal 2 and the atmosphere caused by the wavelength-converted light, that is, the wavelength-converted laser beam. . Furthermore, since the wavelength converter 7d does not need to be a vacuum container, there is an effect that no impurities are generated from the container, and the wavelength converter can be provided at a lower cost.

  Further, the gas 16a flows into a space in contact with the incident end face on which the wavelength-converted light of the nonlinear optical crystal 2 in the container 11 is incident, and then flows out of this space and is flowing. Therefore, even if impurities are generated, they are discharged together with the flowing gas 16a. Further, the gas 16b flows into the space in contact with the emission end face from which the wavelength-converted light of the nonlinear optical crystal 2 in the container 11 is emitted, and then flows out of this space. Even if impurities are generated, they are discharged together with the flowing gas 16b. Therefore, there is an effect that impurities can be prevented from adhering to the nonlinear optical crystal 2 and the optical windows 3a and 3b.

  As in the case of the second embodiment, a heating element 18 and a heat insulating material 19 are provided, and by keeping the nonlinear optical crystal 2 at a constant temperature of 100 ° C. or more, a slight amount of water is contained in the gases 16a and 16b. In this case, moisture is not absorbed, so that the wavelength conversion laser beam can be stably generated for a long period of time. However, the heating element 18 and the heat insulating material 19 need not always be provided.

  In addition, as a gas containing no nitrogen element or containing a small amount of nitrogen element used in Example 4, at least a gas having a lower nitrogen element content than air has a higher atmosphere than a gas in which the atmosphere is air. One that can perform high-power wavelength conversion stably for a long period of time is obtained. However, the volume content of nitrogen is preferably 10% or less, and more preferably 1% or less.

The present inventors conducted further tests in order to investigate the cause of deterioration in wavelength conversion characteristics using a CLBO crystal. For example, by using the wavelength conversion device 7b described in the second embodiment, using a CLBO crystal as the nonlinear optical crystal 2, and making a laser beam having a wavelength of 532 nm incident on the CLBO crystal to convert it into an ultraviolet laser beam having a wavelength of 266 nm, the gas 16 When an oxygen gas (volume content: 99.7%) was used as the sample and the CLBO crystal was placed in an oxygen (O ₂ ) atmosphere and a continuous ultraviolet laser beam generation test was performed for 100 hours, the wavelength of the CLBO crystal was 532 nm. Although there was no change in the laser beam incident end face before the start of the test, there was a case where discoloration was observed in the laser beam passing portion of the CLBO crystal at the 266 nm ultraviolet laser beam emitting end face. There was no change except for the passing portion, and the output was able to maintain 20 W. In addition, when an ultraviolet laser beam generation test was performed using argon gas (volume content: 99.9%) as the gas 16 and placing the CLBO crystal in an argon gas (Ar) atmosphere, the CLBO crystal was Discoloration was observed in the laser beam passing portion of the laser beam incident end facet having a wavelength of 532 nm, but the CLBO crystal ultraviolet laser beam outgoing end face did not sometimes change from that before the start of the test.

Therefore, when a CLBO crystal is used as the nonlinear optical crystal 2, the atmosphere in contact with the emission end face of the UV laser beam having a wavelength of 266 nm of the CLBO crystal is a gas other than oxygen and a gas other than oxygen, such as a gas having a lower nitrogen element content than air. Ar) is a gas atmosphere, and the atmosphere in contact with the laser beam incident end face having a wavelength of 532 nm is a gas other than argon gas, for example, a gas mainly composed of oxygen gas (O ₂ ) or an air atmosphere. Accordingly, the interaction between the nonlinear optical crystal 2 and the atmosphere can be more reliably prevented, so that a high-quality and high-output wavelength-converted laser beam can be generated more stably for a longer period of time. As the nonlinear optical crystal 2, a crystal containing cesium, such as a cesium lithium borate (chemical formula: CsLiB ₆ O ₁₀ , abbreviation: CLBO) crystal, a cesium borate (chemical formula: CsB ₃ O ₅ , abbreviation: CBO) crystal, etc. Is suitable, but lithium borate (chemical formula: LiB ₃ O ₅ , abbreviation: LBO) crystal, beta barium borate (chemical formula: β-BaB ₂ O ₄ , abbreviation: BBO), gadolinium yttrium calcium calcium oxy Even in a crystal that does not contain cesium, such as a borate (chemical formula: Gd _x Y _1-x , Ca ₄ (BO ₃ ) ₃ , abbreviation: GdYCOB) crystal, elements other than cesium react with nitrogen to form a nitrogen compound. It is possible to use it.

  Further, in the fourth embodiment, the example in which the stoppers 14a, 14b, 14c, and 14d are opened and the gases 16a and 16b flow constantly is described, but the space in contact with the entrance end face of the nonlinear optical crystal 2 and the exit end face in the vessel 11 are described. After filling the spaces in contact with the gas 16a and the gas 16b, the stoppers 14a, 14b, 14c and 14d are closed to seal the gas 16a and the gas 16b in the respective spaces in the container 11, that is, the nonlinear optical crystal 2 May be used as a sealed cell, and the same effect as in the fourth embodiment can be obtained. However, in this case, the effect of flowing the gases 16a and 16b cannot be obtained.

  Embodiment 5 FIG.

  FIG. 7 is a diagram for explaining a wavelength conversion method and a wavelength conversion device according to a fifth embodiment for carrying out the present invention, and more specifically, is a longitudinal sectional view of the wavelength conversion device.

  In FIG. 7, 2, 3a, 3b, 4a, 4b, 12a, 12b, 13a, 13b, 14a, 14b, 15a, 15b, 16, 17c, 17d, 18, 19 are shown in Examples 1 and 2 above. It is the same as the one and has the same function. 4c is an O-ring. 11a is a container. 11b is a lid of the container 11a. 45 is a fixing jig for fixing the heat insulating material 19. 46 is an angle adjuster corresponding to a means for adjusting the angle of the nonlinear optical crystal 2 with respect to the incident light. Numeral 47 denotes a position adjuster corresponding to a means for adjusting the passing position of the incident light in the nonlinear optical crystal 2. 7e shows the whole wavelength converter.

  The optical window 3a, 3b, the O-rings 4a, 4b, and the stoppers 14a, 14b are attached to the container 11a, and while the lid 11b is open, the laser beam is passed through the nonlinear optical crystal 2 through the optical windows 3a, 3b. By adjusting the angle of the nonlinear optical crystal 2 with respect to the laser beam by the adjuster 46 and adjusting the laser beam passing position of the nonlinear optical crystal 2 by the position adjuster 47, the output of the wavelength-converted laser beam generated by the nonlinear optical crystal 2 is obtained. Is adjusted to have a desired output, and then the lid 11b is closed to keep the container 11a airtight. Thereafter, by flowing a gas 16 containing no nitrogen element (N) or containing a small amount of nitrogen element, the container 11a is filled with a gas 16 containing no nitrogen element (N) or containing a small amount of nitrogen element. .

  In the fifth embodiment, the wavelength converter 7e is configured as described above, and includes the angle adjuster 46 and the position adjuster 47. Therefore, for example, as described in the fourth embodiment, When operating for a long time at a high output using a gas mainly composed of a gas or an argon gas, discoloration occurs in a laser beam passing portion of a laser beam emitting end face or an incident end face of a CLBO crystal which is a nonlinear optical crystal 2. In such a case, the position adjuster 47 shifts the laser beam passage portion of the nonlinear optical crystal 2 to a place where there is no discoloration, and the angle adjuster 46 adjusts the angle of the nonlinear optical crystal 2 to obtain a wavelength. The output of the converted laser beam can be returned to the output before the laser beam passage portion of the nonlinear optical crystal 2 is deteriorated, and the life of the nonlinear optical crystal 2 is substantially extended. An effect that can be.

  Further, as in the case of the first embodiment, since the nonlinear optical crystal 2 is exposed to the gas 16 containing no nitrogen element or having a low nitrogen element content, the wavelength conversion of the laser beam is performed, and the wavelength is reduced to 400 nm or less. No nitric acid compound such as cesium nitrate is generated even when irradiated with an ultraviolet laser beam, and since the inside of the wavelength conversion device 7e is not evacuated, no impurities are generated from the container. There is an effect that a high-quality and high-output wavelength-converted laser beam can be stably generated. Further, as in the case of the second embodiment, the gas 16 contains a trace amount of moisture by maintaining the nonlinear optical crystal 2 at a constant temperature of 100 ° C. or more, including the heating element 18 and the heat insulating material 19. Even in this case, since the nonlinear optical crystal 2 does not absorb moisture, there is an effect that a wavelength conversion laser beam can be stably generated for a long period of time.

  In the fifth embodiment, the case where the wavelength converter similar to that described in the second embodiment is provided with the angle adjuster 46 and the position adjuster 47 is described. However, the present invention is not limited to this. An angle adjuster 46 and a position adjuster 47 may be provided in a wavelength converter similar to that described in 3 or 4, and a similar effect can be obtained in this case.

  Embodiment 6 FIG.

  FIG. 8 is a diagram for explaining a wavelength conversion method and a wavelength conversion device according to a sixth embodiment for carrying out the present invention, and more specifically, is a longitudinal sectional view of the wavelength conversion device.

  In FIG. 8, 2, 3a, 3b, 4a, 4b, 11, 12a, 12b, 13a, 13b, 14a, 14b, 15a, 15b, 16a, 16b, 17c, 17d, 18, and 19 correspond to the fourth embodiment. They are the same as those shown and perform the same functions. 13e and 13f are holes formed in the container 11. 14e and 14f are stoppers. 15e and 15f are pipes. Reference numeral 15g denotes a pipe, which corresponds to a means for supplying a gas having a nitrogen element content lower than that of air to the vicinity of the emission end face of the nonlinear optical crystal 2. The pipe 15g is connected to a hole 13e for introducing the gas 16b into the container 11, and is disposed so as to extend near the emission end face of the nonlinear optical crystal 2. The hole 13f is provided at a position facing the pipe 15g with the nonlinear optical crystal 2 interposed therebetween. 7f indicates the entire wavelength converter. Although not explicitly shown in FIG. 8, in the container 11, the space in contact with the incident end face of the nonlinear optical crystal 2 and the space in contact with the output end face are separated by, for example, a partition wall. The same as in the case of No. 4.

  The non-linear optical crystal 2 is cut and polished at both ends to a phase matching angle for generating an ultraviolet laser beam having a wavelength of 400 nm or less by wavelength conversion, and is fixed on the container 11 by fixing jigs 17c and 17d. Here, the nonlinear optical crystal 2 is made of a CLBO crystal, and both end faces are cut and polished at a phase matching angle for converting a laser beam having a wavelength of 532 nm into an ultraviolet laser beam having a wavelength of 266 nm. The laser beam enters the container 11 from the optical window 3a on the input side, undergoes wavelength conversion by the nonlinear optical crystal 2, and then exits from the optical window 3b on the output side. The gas 16a enters the space in contact with the incident end face of the nonlinear optical crystal 2 in the container 11 from the pipe 15b through the plug 14b and the hole 13b, and sets the atmosphere in contact with the incident end face of the nonlinear optical crystal 2 to the atmosphere of the gas 16a. The liquid is discharged out of the container 11 through the plug 13a, the plug 14a, and the pipe 15a. The gas 16b flows at a predetermined flow rate (for example, a flow rate of 0.1 liter / minute) from the pipe 15e through the plug 14e, the hole 13e, and the pipe 15g, into the vicinity of the exit end face of the nonlinear optical crystal 2 in the vessel 11, and The atmosphere in contact with the emission end face of the optical crystal 2 is the atmosphere of the gas 16b, and the gas is discharged out of the container 11 through the hole 13f, the plug 14f, and the pipe 15f. The flow rate of the gas 16b is, for example, from a gas cylinder not shown in the figure to a pipe 15e through a flow rate adjustment valve not shown in the figure and a flow meter not shown in the figure. And is measured by a flow meter.

  In the sixth embodiment, the wavelength conversion device 7f is configured as described above, and in addition to the same effects as described in the fourth embodiment, the following effects can be obtained. That is, since the gas 16b is caused to flow into the vicinity of the exit end face of the nonlinear optical crystal 2, even if impurities are generated from constituent materials in the container 11, the impurities have just flowed into the exit end face of the nonlinear optical crystal 2. Since the fresh gas 16b is supplied, impurities are prevented from adhering to the exit end face of the nonlinear optical suspension 2, and furthermore, are prevented from adhering to the portion of the optical window 3b close to the nonlinear optical crystal 2, and stable for a long time. The effect that a high-quality and high-output wavelength-converted laser beam can be generated is enhanced. Further, since the hole 13f is provided at a position opposite to the pipe 15g which is an inlet of the gas 16b into the container 11 with the non-linear optical crystal 2 interposed, impurities are generated from constituent materials in the container 11 temporarily. However, since impurities can be efficiently removed from the inside of the container 11, the impurities can be prevented from adhering to the emission end face of the nonlinear optical crystal 2 and the optical window 3b, and a high-quality and high-output wavelength conversion laser can be stably provided for a long period of time. The effect that a beam can be generated is enhanced.

  In the sixth embodiment, an example in which the gas 16b flows at a flow rate of 0.1 liter / minute has been described. However, if the flow rate is increased to 1 liter / minute and further to 10 liter / minute, the gas in the container 11 is temporarily reduced. Even if impurities are generated from the constituent materials and the like, it is possible to more reliably prevent the impurities from adhering to the exit end face of the nonlinear optical crystal 2 and the portion of the optical window 3b close to the nonlinear optical crystal 2, to stably provide high quality for a long time. The effect that a high-power wavelength-converted laser beam can be generated is further enhanced.

  Further, in the sixth embodiment, the gas 16b is caused to flow into the vicinity of the end face of the nonlinear optical crystal 2 only at the exit end face side of the nonlinear optical crystal 2 and is efficiently discharged from the hole 13f facing the inlet 15g. By providing a similar configuration on the incident end face side of the nonlinear optical crystal 2, even if impurities are generated from the constituent materials in the container 11, the impurities are not incident on the incident end face of the nonlinear optical crystal 2 or the nonlinear optical surface of the optical window 3 a. The effect of preventing adhesion to a portion close to the crystal 2 and generating a high-quality and high-output wavelength-converted laser beam stably for a longer period of time is further enhanced.

  In the sixth embodiment, the case where the pipe 15g is used as a means for supplying the gas 16 to at least the vicinity of the emission end face of the nonlinear optical crystal 2 in the container 11 has been described. However, the present invention is not limited to this. The inner wall of the container 11 may be configured to reach near the end face of the nonlinear optical crystal 2, and the gas 16 may be supplied directly to the vicinity of the end face of the nonlinear optical crystal 2 from the holes 13b and 13e without using the pipe 15g. The same effects as in the sixth embodiment can be obtained.

  Embodiment 7 FIG.

  In the sixth embodiment, as described in the fourth embodiment, the wavelength conversion method of converting the atmosphere in contact with the incident end face of the nonlinear optical crystal 2 and the atmosphere in contact with the output end face into gases 16a and 16b of different components to perform wavelength conversion. In the wavelength converter, a case where a gas having a nitrogen element content lower than that of air is supplied to the vicinity of the entrance end face or the exit end face of the nonlinear optical crystal 2 and then discharged, but the present invention is not limited to this. For example, as described in the first to third embodiments and the fifth embodiment, the wavelength in which the atmosphere in contact with the incident end face and the atmosphere in contact with the emission end face of the nonlinear optical crystal 2 are converted into a gas 16 of the same component to convert the wavelength. In the conversion method and the wavelength conversion device, after supplying the gas 16 having a lower nitrogen element content than air to the vicinity of the entrance end face or the exit end face of the nonlinear optical crystal, It may be discharged.

  FIG. 9 is a diagram for explaining a wavelength conversion method and a wavelength conversion device according to a seventh embodiment for carrying out the present invention, and more specifically, is a longitudinal sectional view of the wavelength conversion device.

  In FIG. 9, 2, 3a, 3b, 4a, 4b, 12a, 12b, 13a, 13b, 14a, 14b, 15a, 15b, 16, 17c, 17d, 18, and 19 are shown in Examples 1 and 2 above. It is the same as the one and has the same function. Further, 15 g is a pipe similar to that described in the sixth embodiment, and corresponds to a means for supplying a gas 16 having a lower nitrogen element content than air to the vicinity of the emission end face of the nonlinear optical crystal. 7g indicates that the wavelength converter is completely off.

  The laser beam enters the container 11 from the optical window 3a on the input side, undergoes wavelength conversion by the nonlinear optical crystal 2, and then exits from the optical window 3b on the output side.

  At a predetermined flow rate (for example, a flow rate of 0.1 liter / minute), the gas 16 passes from the pipe 15b through the plug 14b, the hole 13b, and the pipe 15g connected to the hole 13b, and the emission end face of the nonlinear optical crystal 2 in the container 11. The gas flows into the vicinity and is brought into contact with the emission end face of the nonlinear optical crystal 2 as the gas 16 atmosphere, and is discharged out of the container 11 through the hole 13a, the plug 14a, and the pipe 15a. The flow rate of the gas 16 is, for example, from a gas cylinder not shown in the figure to a pipe 15b through a flow control valve not shown in the figure and a flow meter not shown in the figure. And is measured by a flow meter.

  In the seventh embodiment, the wavelength conversion device 7g is configured as described above, and in addition to the same effects as described in the second embodiment, the following effects can be obtained.

  That is, since the gas 16 is caused to flow into the vicinity of the emission end face of the nonlinear optical crystal 2, even if impurities are generated from constituent materials in the container 11, the gas just flows into the emission end face of the nonlinear optical crystal 2. Since the fresh gas 16 is supplied, impurities are prevented from adhering to the exit end face of the nonlinear optical crystal 2, and furthermore, are prevented from adhering to a portion of the optical window 3b close to the nonlinear optical crystal 2, and stable for a long time. The effect of being able to generate a high-quality and high-output wavelength-converted laser beam is enhanced.

  Further, in the above-described embodiment 7, an example in which the gas 16b is flowed at a flow rate of 0.1 liter / minute has been described. However, by increasing the flow rate to 1 liter / minute, and further to 10 liter / minute, the gas in the container 11 is temporarily set. Even if impurities are generated from the constituent materials and the like, it is possible to more reliably prevent the impurities from adhering to the exit end face of the nonlinear optical crystal 2 and the portion of the optical window 3b close to the nonlinear optical crystal 2, to stably provide high quality for a long time. The effect that a high-power wavelength-converted laser beam can be generated is further enhanced.

  In the seventh embodiment, the gas 16 is supplied to the vicinity of the exit end face of the nonlinear optical crystal 2. However, the gas 16 is supplied to both the exit end face and the entrance end face of the nonlinear optical crystal 2. May be.

  In the seventh embodiment, a means (pipe 15g) for supplying the gas 16 to at least the vicinity of the emission end face 10 of the nonlinear optical crystal 2 in the container 11 is added to the wavelength converter similar to that described in the second embodiment. Although the case where the nonlinear optical crystal 2 is provided has been described above, the present invention is not limited to this. A means (pipe 15g) for supplying to the vicinity may be provided, and in this case, the same effect is obtained.

  In the seventh embodiment, the case where the pipe 15g is used as a means for supplying the gas 16 to the vicinity of the entrance end face or the exit end face of the nonlinear optical crystal 2 in the container 11 has been described. However, the present invention is not limited to this. For example, the inner wall of the container 11 may be configured to reach the vicinity of the end face of the nonlinear optical crystal 2, and the gas 16 may be supplied to the vicinity of the end face of the nonlinear optical crystal 2 directly from the holes 13b and 13e without using the pipe 15g. Thus, the same effect as in the seventh embodiment can be obtained.

  Embodiment 8 FIG.

  FIG. 10 is a view for explaining a wavelength conversion laser device according to an eighth embodiment for carrying out the present invention, and more specifically, is a longitudinal sectional view of the wavelength conversion laser device.

  In FIG. 10, reference numeral 2 denotes a nonlinear optical crystal. 7a is the wavelength converter shown in the first embodiment. Reference numeral 20 denotes a laser device that generates a laser beam having a wavelength of 532 nm, which is the second harmonic of a neodymium yag (Nd: YAG) laser. Reference numeral 21 denotes a laser beam having a wavelength of 532 nm emitted from the laser device 20. Reference numeral 21a denotes a laser beam in which a part of the laser beam 21 having a wavelength of 532 nm is converted into a wavelength of 266 nm by the nonlinear optical crystal 2. Reference numeral 22 denotes a wavelength selecting mirror coated with a coating that transmits a laser beam having a wavelength of 266 nm and reflects a laser beam having a wavelength of 532 nm. Reference numeral 21b denotes an ultraviolet laser beam having a wavelength of 266 nm. 23 is a base. Reference numeral 24 denotes a fixing table for fixing the wavelength conversion device 7a on the base 23. Reference numeral 25 denotes a fixing jig for fixing the wavelength selection mirror 22 on the base 23. Reference numeral 26 denotes the entire wavelength conversion laser device.

The nonlinear optical crystal 2 includes, 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, and lithium borate (chemical formula: LiB) ₃ O ₅ , abbreviation: LBO) crystal, beta barium borate (chemical formula: β-BaB ₂ O ₄ , abbreviation: BBO), gadolinium yttrium calcium calcium oxyborate (chemical formula: Gd _x Y _1-x Ca ₄ ( BO ₃ ) ₃ (abbreviation: GdYCOB) crystal or the like, and both end faces are cut and polished to a phase matching angle for generating an ultraviolet laser beam having a wavelength of 400 nm or less by wavelength conversion, and are fixed by fixing jigs 17a and 17b. It is fixed on the container 11. Here, the nonlinear optical crystal 2 is made of a CLBO crystal, and both end faces are cut and polished at a type 1 phase matching angle for converting a laser beam having a wavelength of 532 nm into an ultraviolet laser beam having a wavelength of 266 nm.

  The laser beam 21 having a wavelength of 532 nm emitted from the laser device 20 is incident on the wavelength conversion device 7a, and a part of the laser beam 21 is converted to a wavelength of 266 nm by the nonlinear optical crystal 2 to become a laser beam 21a. The laser beam 21a is transmitted by the wavelength selection mirror 22 only at a wavelength of 266 nm, and is reflected at a wavelength of 532 nm, thereby becoming an ultraviolet laser beam 21b having a wavelength of 266 nm.

  In the eighth embodiment, the wavelength conversion laser device is configured as described above, and the nonlinear optical crystal 2 is exposed to a gas containing no nitrogen element or containing little nitrogen element. As a result, even when irradiated with an ultraviolet laser beam having a wavelength of 400 nm or less due to wavelength conversion, a nitrate compound such as cesium nitrate is not generated, so that a high-quality and high-output wavelength-converted laser beam is stably generated for a long period of time. It has the effect of being able to. In addition, since the wavelength conversion device 7a does not need to be a vacuum container, there is an effect that no impurities are generated from the container and a wavelength conversion laser device can be provided at low cost.

  In the eighth embodiment, the example using the wavelength converter 7a shown in the first embodiment is described. However, any one of the wavelength converters 7b to 7g shown in the second to seventh embodiments may be used. The same effects as those of the eighth embodiment can be obtained.

In the eighth embodiment, an example in which a laser device 20 that generates a laser beam having a wavelength of 532 nm, which is the second harmonic of a neodymium-yag (Nd: YAG, chemical formula: Nd: Y ₃ Al ₅ O ₁₂ ) laser, is used as a light source. However, the wavelength of the light source is not limited to this, and for example, ytterbium yag (Yb: YAG, chemical formula Yb: Y ₃ Al ₅ O ₁₂ ), neodymium ylf (Nd: YLF, chemical formula Nd: LiYF ₄ ) , Nd: YVO ₄ , titanium / sapphire (Ti: Al ₂ O ₃ ) fundamental wave, second harmonic wave, and the like, and the same effects as those of the eighth embodiment can be obtained.

  Embodiment 9 FIG.

  FIG. 11 is a view for explaining a laser beam machine according to a ninth embodiment for carrying out the present invention, and is more specifically a longitudinal sectional view of the laser beam machine.

  In FIG. 11, reference numeral 26 denotes the wavelength conversion laser device shown in the eighth embodiment. 27 is a galvanomirror. Reference numeral 28 denotes a galvanomirror fixing jig for fixing the galvanomirror 27 so as to variably change the angle with respect to the ultraviolet laser beam 21b having a wavelength of 266 nm emitted from the wavelength conversion laser device 26. 29 is an fθ lens. Reference numeral 30 denotes an fθ lens fixing jig. 31 is a mirror lens fixing jig. Reference numeral 32 denotes a processed product such as a printed board or a green sheet, which is a glass epoxy printed board in this case. 33 is a processing machine base. Reference numeral 34 denotes a processing machine including a galvanometer mirror 27, a galvanometer mirror fixing jig 28, an fθ lens 29, an fθ lens fixing jig 30, a mirror lens fixing jig 31, and a processing machine base 33.

  The galvanomirror 27 is fixed to a mirror lens fixing jig 31 by a galvanomirror fixing jig 28, and is fixed on a processing machine base 33. lens 29 is fixed to a mirror lens fixing jig 31 by an fθ lens fixing jig 30, and is fixed on a processing machine base 33.

  The wavelength conversion laser beam 21b emitted from the wavelength conversion laser device 26 enters the galvanometer mirror 27, and the traveling direction is variably changed by the galvanometer mirror 27. The wavelength-converted laser beam 21b whose traveling direction has been changed is incident on the fθ lens 29 and is focused on the workpiece 32. The focused wavelength-converted laser beam 21b makes a hole in the workpiece 32.

  In the ninth embodiment, the laser processing machine is configured as described above, and the wavelength conversion laser device 26 can stably generate the wavelength conversion laser beam 21b for a long period of time. The present invention provides a method of manufacturing a high-quality printed circuit board, which has an effect of being able to perform various processes. In addition, since the wavelength converter 7a does not need to be a vacuum vessel, there is an effect that a laser processing machine can be provided at low cost.

  In FIG. 11, the galvanomirror 27 is provided to change the traveling direction of the wavelength-converted laser beam 21b variably, but the movable base for moving the workpiece 32 such as the XY stage on the base 33 is shown. May be provided, and both the galvanometer mirror 27 and the movable base may be provided.

  Further, although the case where the fθ lens 29 is provided is shown, a plano-convex lens, a biconvex lens, or the like may be provided.

  In the ninth embodiment, the example of the processing of making a hole in the workpiece 32 made of a glass epoxy printed board has been described, but the workpiece 32 may be a printed board of other material, a green sheet, an electronic component, a metal, a glass, or the like. For example, any processing such as cutting, welding, engraving, marking, and forming may be used. It has the same effect as.

  For example, when the workpiece 32 is an optical fiber and a fiber grating is produced by causing a periodic change in the refractive index of the optical fiber, the wavelength conversion laser device 26 is a high-quality wavelength conversion laser beam 21b that is stable and has no distortion for a long time. Therefore, it is possible to provide a method of manufacturing a high-quality fiber grating, which has an effect that uniform processing can be performed stably and accurately with a long period of time.

  The wavelength conversion method and the wavelength conversion device according to the present invention can be used for, for example, a wavelength conversion laser device, and a laser beam machine can be configured using the wavelength conversion laser device. Since such a laser processing machine can stably and accurately perform uniform processing for a long period of time, it can be advantageously used in various processing such as production of a printed circuit board and production of a fiber grating.

1 is a longitudinal sectional view of a wavelength converter according to a first embodiment of the present invention. 1 is a longitudinal sectional view of a wavelength converter according to a first embodiment of the present invention. FIG. 6 is a longitudinal sectional view of a wavelength converter according to a second embodiment of the present invention. FIG. 6 is a longitudinal sectional view of a wavelength converter according to a second embodiment of the present invention. FIG. 9 is a longitudinal sectional view of a wavelength conversion device according to a third embodiment of the present invention. FIG. 11 is a longitudinal sectional view of a wavelength conversion device according to a fourth embodiment of the present invention. FIG. 13 is a longitudinal sectional view of a wavelength conversion device according to a fifth embodiment of the present invention. FIG. 13 is a longitudinal sectional view of a wavelength conversion device according to a sixth embodiment of the present invention. FIG. 13 is a longitudinal sectional view of a wavelength converter according to a seventh embodiment of the present invention. FIG. 16 is a longitudinal sectional view of a wavelength conversion laser device according to an eighth embodiment of the present invention. FIG. 16 is a vertical sectional view of a laser beam machine according to a ninth embodiment of the present invention. It is a longitudinal section of the conventional wavelength converter.

Explanation of reference numerals

  2 Nonlinear optical crystal, 3a, 3b optical window, 4a, 4b O-ring, 7a wavelength converter, 11 container, 12a, 12b optical window holder, 13a, 13b hole, 14a, 14b plug, 15a, 15b pipe, 16 gas, 17a, 17b Fixing jig.

Claims (14)

  In a wavelength conversion method of passing light through a nonlinear optical crystal for wavelength conversion, the nonlinear optical crystal contains cesium, and an atmosphere in contact with a surface from which the wavelength-converted light of the nonlinear optical crystal exits is mainly composed of carbon dioxide gas. A wavelength conversion method characterized by converting a wavelength into a gas to be converted.   The wavelength conversion method according to claim 1, wherein the gas is a gas having a volume content of a gas containing nitrogen gas of 10% or less.   2. The wavelength according to claim 1, wherein a wavelength of the non-linear optical crystal is converted by covering an incident end face of the nonlinear optical crystal on which the light to be wavelength-converted is incident and an emission end face from which the wavelength-converted light is emitted with the gas. Conversion method.   The wavelength conversion of the nonlinear optical crystal is performed by converting the atmosphere in contact with the incident end face on which the wavelength-converted light is incident and the atmosphere in contact with the emission end face from which the wavelength-converted light exits with the above-mentioned gases having different components and performing wavelength conversion. The wavelength conversion method according to claim 1.   The wavelength conversion method according to claim 1, wherein the gas is circulated.   5. The wavelength conversion method according to claim 4, wherein the gas is supplied to at least the vicinity of the emission end face of the nonlinear optical crystal and then discharged.   In a wavelength conversion device for converting the wavelength of light by passing the light through a nonlinear optical crystal, the nonlinear optical crystal contains cesium, and an atmosphere in contact with a surface from which the wavelength-converted light of the nonlinear optical crystal is emitted mainly includes carbon dioxide gas. A wavelength conversion device comprising means for converting a gas into a gas.   The wavelength converter according to claim 7, wherein the wavelength-converted light having an average power of 5 W or more is emitted.   The wavelength converter according to claim 7, wherein the gas is a gas having a volume content of a gas containing nitrogen gas of 10% or less.   8. The wavelength conversion device according to claim 7, further comprising means for covering the incident end face of the nonlinear optical crystal on which the wavelength-converted light is incident and the emission end face from which the wavelength-converted light is emitted with the gas. apparatus.   An atmosphere in contact with an incident end face on which the wavelength-converted light of the nonlinear optical crystal is incident, and an atmosphere in contact with an exit end face on which the wavelength-converted light is emitted are provided with a means for using the gas of a different component. The wavelength converter according to claim 7, wherein   8. The wavelength conversion device according to claim 7, further comprising means for circulating the gas.   Means for disposing a nonlinear optical crystal in a container provided with a window or an opening for partially passing incident light and output light, and supplying the gas to at least a vicinity of an output end face of the nonlinear optical crystal in the container; 13. The wavelength conversion device according to claim 12, further comprising means for discharging the supplied gas from said container.   With a processing machine, as a processing light source, a laser device serving as a light source for wavelength conversion, and the nonlinear optical crystal contains cesium, the atmosphere in contact with the surface of the nonlinear optical crystal from which the wavelength-converted light exits, a carbon dioxide gas. A laser processing machine, comprising: a wavelength conversion laser device, comprising: means for forming a gas as a main component; and a wavelength conversion device for converting a wavelength of the laser light from the laser device through the nonlinear optical crystal.

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