JP3636200B2 - Wavelength conversion method, wavelength converter, and laser processing machine - Google Patents

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 conversion device disclosed in Patent Document 1, for example. In FIG. 12, 1 is a vacuum vessel, 2 is a nonlinear optical crystal such as a cesium lithium borate (chemical formula: CsLiB ₆ 0 ₁₀ , abbreviation: CLBO) crystal, 3a and 3b are optical windows, 4a, 4b and 4c are O-rings, 5 are vacuum sealing valves, 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 chamber 1 from the optical window 3a on the input side, interacts with the nonlinear optical crystal 2, undergoes wavelength conversion, and then exits from the optical window 3b on the output side. 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 3a, 3b and the vacuum sealing valve 5 is sealed by O-rings 4a, 4b, 4c. The inside of the vacuum vessel 1 is maintained in a vacuum.

  Inside the vacuum vessel 1, the nonlinear optical crystal 2 is pressed from the top by a fixing metal 6 and 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 likely to be generated from a vacuum vessel, an O-ring, a fixture, etc. exposed to the vacuum, and the impurities are nonlinear. Since the optical crystal 2 (wavelength conversion crystal) is attached to the optical window, the wavelength conversion laser beam (that is, the light subjected to wavelength conversion by the nonlinear optical crystal) cannot be stably generated for a long period of time. There is a problem that it is necessary and the apparatus becomes expensive.

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

  The wavelength conversion method according to the present invention is the wavelength conversion method of converting the wavelength of light through a nonlinear optical crystal, wherein the atmosphere in contact with the emission end face from which the wavelength-converted light of the nonlinear optical crystal is emitted is a nitrogen element content rate. Is a gas smaller than air to convert the wavelength.

  According to this, the effect that the light wavelength-converted by the nonlinear optical crystal can be stably generated for a long time can be obtained.

  Further, the wavelength conversion is performed by covering the incident end face where the wavelength-converted light of the nonlinear optical crystal is incident and the exit end face where the wavelength-converted light is emitted with a gas having a nitrogen element content smaller than that of air.

  According to this, the effect that the light wavelength-converted by the nonlinear optical crystal can be generated more reliably and stably for a long time can be obtained.

  In addition, the atmosphere in contact with the incident end face on which the wavelength-converted light of the nonlinear optical crystal is incident and the atmosphere in contact with the exit end face from which the wavelength-converted light is emitted are converted into different component gases for 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 it can be obtained.

  Moreover, the gas whose nitrogen element content rate is smaller than air is circulated.

  According to this, even if impurities are generated, they are discharged together with the flowing gas, so that it is possible to prevent the impurities from adhering to the nonlinear optical crystal and the optical window.

  Further, a gas having a nitrogen element content smaller than 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 impurities are generated, since fresh gas is supplied in the vicinity of the nonlinear optical crystal, it is possible to more reliably prevent the impurities from adhering to the nonlinear optical crystal. It is done.

  Moreover, the gas whose nitrogen element content rate is smaller than air is a gas whose volume content rate of the gas containing nitrogen element is 10% or less.

  According to this, the effect that the light wavelength-converted by the nonlinear optical crystal can be stably generated for a long time with a simple configuration is obtained.

  The nonlinear optical crystal is a crystal containing cesium. According to this, the effect that the high output light of the ultraviolet region wavelength-converted by the nonlinear optical crystal can be stably generated for a long time can be obtained.

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

  According to this, the effect that the light wavelength-converted by the nonlinear optical crystal can be stably generated for a long time with a simpler configuration can be obtained.

  Moreover, the gas whose nitrogen element content is smaller than air, which is inferior to the surface where the wavelength-converted light of the nonlinear optical crystal 1 exits, is a gas mainly composed of argon gas.

  According to this, the effect that the light wavelength-converted by the nonlinear optical crystal can be generated more reliably and stably for a long time can be obtained.

  The wavelength conversion device according to the present invention is a wavelength conversion device that converts the wavelength of light through a nonlinear optical crystal, and the atmosphere in contact with the surface from which the wavelength-converted light of the nonlinear optical crystal is emitted has a nitrogen element content rate. Means for making the gas smaller than air is provided.

  According to this, the effect that the light wavelength-converted by the nonlinear optical crystal can be stably generated for a long time can be obtained.

  In addition, the light whose wavelength is converted with an average power of 5 W or more is emitted.

  According to this, the effect that the high output light wavelength-converted by the nonlinear optical crystal can be stably generated for a long period of time can be obtained.

  In addition, a means for covering the nonlinear optical crystal with a gas whose nitrogen element content is lower than air is provided.

  According to this, the effect that the light wavelength-converted by the nonlinear optical crystal can be generated more reliably and stably for a long time can be obtained.

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

  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 it can be obtained.

  Moreover, a means for circulating a gas having a nitrogen element content smaller than air is provided.

  According to this, even if impurities are generated, they are discharged together with the flowing gas, so that it is possible to prevent the impurities from adhering to the nonlinear optical crystal and the optical window.

  Further, the nonlinear optical crystal is disposed in a container partially provided with a window or an opening through which incident light and outgoing light pass, and a gas having a nitrogen element content smaller than air is at least contained in the container. Means for supplying in the vicinity of the emission end face and means for discharging the supplied gas from the container are provided.

  According to this, even if impurities are generated, since fresh gas is supplied in the vicinity of the nonlinear optical crystal, it is possible to more reliably prevent the impurities from adhering to the nonlinear optical crystal. It is done.

  Moreover, the gas whose nitrogen element content rate is smaller than air is a gas whose volume content rate of the gas containing nitrogen element is 10% or less.

  According to this, the effect that the light wavelength-converted by the nonlinear optical crystal can be stably generated for a long time with a simple configuration is obtained.

  The nonlinear optical crystal is a crystal containing cesium.

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

  Moreover, the gas whose nitrogen element content is lower than air is a gas mainly composed of any of rare gas, oxygen gas, and carbon dioxide gas.

  According to this, the effect that the light wavelength-converted by the nonlinear optical crystal can be stably generated for a long time with a simpler configuration can be obtained.

  In addition, the gas having a nitrogen element content smaller than air and serving as an atmosphere in contact with the light emitting surface of the nonlinear optical crystal is a gas mainly composed of argon gas.

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

  According to this, there is an effect that uniform processing can be performed stably and accurately for a long period of time.

  In order to investigate the cause of deterioration of wavelength conversion characteristics using a CLBO crystal, the present inventors generate a second harmonic of a neodymium-yag (Nd: YAG) laser with a wavelength of 1064 nm, that is, a laser device that generates a laser beam with a wavelength of 532 nm. Was used as a light source, and an ultraviolet laser beam having a wavelength of 266 nm, which is the fourth harmonic of the Nd: YAG laser, was continuously generated for 100 hours using a CLBO crystal. When this continuous ultraviolet laser beam was generated, the CLBO crystal was placed on a heater in air and used at a constant temperature of 140 ° C. Further, 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, a newly attached substance was observed on the UV laser beam emitting end face of the CLBO crystal, that is, the face from which the wavelength-converted light was emitted. As a result of elemental analysis and structural analysis of the rice bran substance, it was found that the adhering substance was a nitrate compound containing cesium nitrate (CsNO ₃ ). This cesium nitrate is observed only on the UV laser beam emission end face of the CLBO crystal, and since cesium is an element not included in components other than the CLBO crystal used for wavelength conversion, it has a wavelength of 266 nm generated by wavelength conversion. It is apparent that cesium nitrate, which is a component of the CLB ○ crystal, reacts with nitrogen in the atmosphere by the action of the ultraviolet laser beam to generate cesium nitrate. In addition, the generation of cesium nitrate by wavelength conversion using a CLBO crystal is a phenomenon that has been revealed for the first time by a long-term continuous ultraviolet laser beam generation test conducted by the present inventors at an average power of 5 W or more. Conventionally, for example, as shown in the literature (Kazunari Kabutsu et al., IEEJ Optical and Quantum Device Study Material, OQD-97, 53-69, 41-46, 1997), the output is 4 W or less. This phenomenon was not clarified because only the long-term operation test was conducted.

  From the above results, when wavelength conversion is performed using a CLBO crystal, the atmosphere in contact with the emission end face from which at least the wavelength-converted light of the nonlinear optical crystal is emitted becomes a gas having a smaller nitrogen element content than air. In this way, it is possible to perform wavelength conversion with high output stably for a long period of time compared to the case where the atmosphere is air, preferably by making the gas almost free of nitrogen element (N). Became clear.

  Example 1.

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

  In FIGS. 1 and 2, 2 is a nonlinear optical crystal. Reference numerals 3a and 3b denote optical windows that transmit the laser beam. Reference numerals 4a and 4b denote O-rings. Reference numeral 11 denotes a container for housing the nonlinear optical crystal 2. Reference numerals 12a and 12b denote optical window holders. Reference numerals 13 a and 13 b denote holes formed in the container 11. 14a and 14b are stoppers. 15a and 15b are pipes. Reference numeral 16 denotes a gas that does not contain nitrogen element (N) or contains little nitrogen element. Reference numerals 17 a and 17 b denote fixing jigs for fixing the nonlinear optical crystal 2 to the container 11. 7a shows the whole wavelength converter.

  Both ends of the nonlinear optical crystal 2 are cut and polished at a phase matching angle for generating an ultraviolet laser beam having a wavelength of 400 nm or less by wavelength conversion, and 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 ) that is transparent to a laser beam having a wavelength of at least 200 nm to 1500 nm. It is closely attached to the container 11 by optical window holders 12a and 12b via 4a and 4b. Here, the stoppers 14a and 14b are those that are directly joined to the container 11 with PT screws (tube taper screws). The container 11 is kept airtight by the optical windows 3a and 3b, the O-rings 4a and 4b, and the stoppers 14a and 14b.

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

The gas 16 does not contain nitrogen element (N) as a component, or is a gas containing little nitrogen element. For example, a gas mainly composed of rare gas, oxygen gas (O ₂ ), carbon dioxide gas (CO ₂ ), or the like is used. It can flow into the container 11 through the pipe 15a and the plug 14a with a hole, and always flows out from the container 11 through the plug 14b and the pipe 15b with a hole. For this reason, the inside 11 of the container is filled with a gas 16 that does not contain nitrogen element or has little nitrogen element.

  In the first embodiment, the wavelength conversion device 7a is configured as described above, and the incident end face on which the wavelength-converted light of the nonlinear optical crystal 2 is incident and the exit end face on which the wavelength-converted light is emitted are components. Is exposed to a gas 16 that does not contain nitrogen element or is low in nitrogen element. Therefore, even if laser beam wavelength conversion is performed and irradiation with an ultraviolet laser beam having a wavelength of 400 nm or less is performed, nitrate compounds such as cesium nitrate are Since the wavelength conversion laser beam is not generated and the wavelength conversion laser beam is not distorted and the output is not further reduced, and the inside of the wavelength conversion device 7a is not evacuated. It does not occur, and impurities do not adhere to the nonlinear optical crystal 2 or the optical window. It achieves the effect rack that can be generated.

  In addition, since the gas 16 flows into the container 11 and flows so as to always flow out of the container 11 and is in circulation, even if impurities are generated, it is discharged together with the gas 16 that is in circulation. Therefore, it is possible to prevent impurities from adhering to the nonlinear optical crystal 2 and the optical windows 3a and 3b.

  In addition, the wavelength conversion device 7a does not need to be a strict airtight container, and can generate a wavelength conversion laser beam with high output stably for a long period of time only by flowing a small amount of rare gas, oxygen, carbon dioxide gas or the like. As a result, the wavelength converter can be provided at a low cost.

The nonlinear optical crystal 2 includes crystals containing cesium such as cesium lithium borate (chemical formula: CsLiB ₆ O ₁₀ , abbreviation: CLBO) crystal and cesium borate (chemical formula: CsB ₃ O ₅ , abbreviation: CBO) crystal. Are suitable for 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 oxy. Even a cesium-free crystal such as a borate (chemical formula: Gd _x Y _1-x Ca ₄ (BO ₃ ) ₃ , abbreviation: GdYCOB) crystal can react with nitrogen to form a nitrogen compound. It can be used.

  Moreover, although the cylindrical thing was shown as an example as the container 11, any shape may be sufficient, for example, a cube or a rectangular parallelepiped may be sufficient.

  Moreover, although what was directly joined to the container 11 by PT screw, O-ring etc. was shown as plug 14a, 14b, what was provided in the middle of this other piping etc. can be used.

  In the first embodiment, the example in which the stoppers 14a and 14b are opened and the gas 16 containing no nitrogen element or constantly flowing the gas 16 containing little nitrogen element has been described. However, the container 11 does not contain nitrogen element or nitrogen element. After filling with a small amount of gas 16, the stoppers 14 a and 14 b may be closed to seal the gas 16 in the container 11, that is, a non-linear optical crystal sealed cell may be used. Has the same effect. However, in this case, the effect due to the circulation of the gas 16 cannot be obtained.

  Example 2.

  3 and 4 are diagrams for explaining a wavelength conversion method and a wavelength conversion apparatus according to Embodiment 2 for carrying out the present invention. More specifically, FIG. 3 shows a wavelength conversion apparatus. FIG. 4 is a longitudinal sectional view, and FIG. 4 is a transverse sectional view of the wavelength converter.

  3 and 4, 2, 3a, 3b, 4a, 4b, 11, 12a, 12b, 13a, 13b, 14a, 14b, 15a, 15b, and 16 are the same as those shown in the first embodiment. And has the same effect. Reference numerals 17 c and 17 d denote fixing jigs for fixing the nonlinear optical crystal 2 on the heating element 18. Reference numeral 18 denotes a heating element provided with an electric heater. Reference numeral 19 denotes 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 converter 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 the temperature sensor, and is controlled to a constant temperature exceeding 100 ° C., whereby the fixing jigs 17c and 17d and the nonlinear optical crystal 2 are controlled. Is maintained at a constant temperature of 100 ° C. or higher.

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

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

  Similarly to the case of Example 1, the incident end face on which the wavelength-converted light of the nonlinear optical crystal 2 is incident and the exit end face on which the wavelength-converted light is emitted do not contain nitrogen elements in the components, or the nitrogen element Is exposed to a gas 16 having a small amount of light, and a wavelength conversion of a laser beam is performed, and even when 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 the inside of 7a is not evacuated, impurities are not generated from the container, so that it is possible to generate a wavelength conversion laser beam with high quality and high output stably for a long period of time. Further, since the wavelength conversion army 7b does not need to be a vacuum vessel, the wavelength conversion device can be provided at a low cost.

  Further, even if impurities are generated, they are discharged together with the flowing gas 16, so that it is possible to prevent the impurities from adhering to the nonlinear optical crystal 2 and the optical windows 3a and 3b.

  In addition, although the cylindrical thing was shown as an example as the container 11, any shape may be sufficient, for example, a cube or a rectangular parallelepiped may be sufficient.

  Moreover, although what was directly joined to the container 11 by PT screw, O-ring etc. was shown as plug 14a, 14b, what was provided in the middle of this other piping etc. can be used.

  Moreover, although the example provided with the electric heater as the heating element 18 was shown, it does not restrict to this, For example, what is necessary is just to provide the element which can be heated, such as a Peltier element.

  Further, in the second embodiment, an example in which the stoppers 14a and 14b are opened and the gas 16 containing no nitrogen element or constantly flowing the gas 16 containing little nitrogen element has been described. However, the container 11 does not contain nitrogen element or nitrogen element. After filling with a small amount of gas 16, the stoppers 14 a and 14 b may be closed to seal the gas 16 in the container 11, which has the same effect as in the second embodiment. However, in this case, the effect due to the circulation of the gas 16 cannot be obtained.

  Example 3

  FIG. 5 is a view for explaining a wavelength conversion method and a wavelength conversion apparatus according to Embodiment 3 for carrying out the present invention, and more specifically, is a longitudinal sectional view of the wavelength conversion apparatus.

  In FIG. 5, reference numerals 2, 16, 17a and 17b are the same as those shown in the first embodiment and have the same function. 35 is a container body, 36a and 36b are lids, and 37 is a container. Reference numerals 38a and 38b denote holes through which light is formed in the lids 36a and 36b. 13 c 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 body 35 and the lids 36a and 36b constitute a container 37, and a hole 38a and a hole 38b through which light passes are formed in the lid 36a and the lid 36b, respectively.

  A gas 16 mainly composed of a gas other than nitrogen, such as a rare gas, oxygen gas, carbon dioxide gas, or the like, flows into the container 37 from the hole 13c provided in the container body 35 through the pipe 15c. Let The gas 16 replaces the air in the container 37 to fill the container 37 with the gas 16 and is discharged from the holes 38a and 38b.

  Thus, the container 37 does not necessarily need to be airtight, and the atmosphere of the nonlinear optical crystal 2 may be a gas that does not contain a nitrogen element or contains a small amount of nitrogen element. Further, at least the gas in contact with the surface from which the wavelength-converted light 5 of the nonlinear optical crystal 2 exits may be a gas containing no nitrogen element or a gas containing little 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 Examples 1 to 3 described so far, the atmosphere of the nonlinear optical crystal 2 does not contain nitrogen element or is a gas containing less nitrogen element. However, at least the nitrogen element content is lower than air. If so, wavelength conversion with high output can be stably performed for a long period of 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 noble gas, oxygen gas, carbon dioxide gas, etc., which flows or encloses in the container in which the nonlinear optical crystal 2 is disposed, does not have to be a high purity gas, and an inexpensive gas with a low grade is used. it can. The gas mainly composed of noble gas, oxygen gas, carbon dioxide gas or the like preferably has a volume content of these gases of, for example, 50% or more, more preferably 90% or more, and even more preferably 99% or more.

  Example 4

  FIG. 6 is a view for explaining a wavelength conversion method and a wavelength conversion apparatus according to Embodiment 4 for carrying out the present invention, and more specifically, is a longitudinal sectional view of the wavelength conversion apparatus.

  In FIG. 6, 2, 3a, 3b, 4a, 4b, 11, 12a, 12b, 17c, 17d, 18, and 19 are the same as those shown in Example 1 or 2, and have the same function. To do. Reference numerals 13 a, 13 b, 13 c, and 13 d are holes formed in the container 11. 14a, 14b, 14c and 14d are stoppers. Reference numerals 15a, 15b, 15c and 15d are pipes. 16b is a gas which does not contain nitrogen element (N) in its component or has little nitrogen element. 16a is a gas composed of a component different from that of the gas 16b. 7d shows the whole wavelength converter. Although not clearly shown in FIG. 6, in the container 11, a space in contact with the incident end face on which the wavelength-converted light of the nonlinear optical crystal 2 is incident and a space in contact with the exit end face from which the wavelength-converted light is emitted. Are separated by, for example, a partition wall.

  Both ends of the nonlinear optical crystal 2 are cut and polished at a phase matching angle for generating an ultraviolet laser beam having a wavelength of 400 nm or less by wavelength conversion, and 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 the atmosphere in contact with the incident end face of the nonlinear optical crystal 2 is the atmosphere of the gas 16a. It is discharged out of the container 11 through 13a, the stopper 14a, and the pipe 15a. Further, 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 the atmosphere in contact with the emission end face of the nonlinear optical crystal 2 is the atmosphere of the gas 16b. , Through the hole 13d, the stopper 14d, and the pipe 15d, and discharged to the outside 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 a gas 16b that does not contain nitrogen element or contains 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, nitric acid compounds such as cesium nitrate are not generated. Since the wavelength-converted laser beam is not distorted or the output is not reduced, the wavelength-converted laser beam having high quality and high output can be stably generated for a long period of time.

  In addition, since the atmosphere in contact with the incident end face of the nonlinear optical crystal 2 and the atmosphere in contact with the exit end face are made of the gas 16a and the gas 16b having different components, it is caused by the wavelength-converted light, that is, the incident laser beam that becomes the fundamental wave of wavelength conversion. There is an effect that 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 conversion laser beam, can be individually and efficiently prevented. . Furthermore, since the wavelength converter 7d does not need to be a vacuum container, impurities are not generated from the container, and the wavelength converter can be provided at a lower cost.

  In addition, the gas 16a is circulated so as to flow out from this space after flowing into the space in contact with the incident end face on which the wavelength-converted light of the nonlinear optical crystal 2 in the container 11 enters. 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 exits, and then flows out so as to flow out of this space. Even if impurities are generated, they are discharged together with the flowing gas 16b. Therefore, it is possible to prevent impurities from adhering to the nonlinear optical crystal 2 and the optical windows 3a and 3b.

  Further, as in the case of the second embodiment, the heating element 18 and the heat insulating material 19 are provided, and by keeping the nonlinear optical crystal 2 at a constant temperature of 100 ° C. or higher, the gases 16a and 16b contain a trace amount of moisture. In this case, since the moisture is not absorbed, the wavelength conversion laser beam can be generated stably for a long period of time. However, the heating element 18 and the heat insulating material 19 are not necessarily provided.

  In addition, as a gas which does not contain the nitrogen element used in this Example 4, or has a small amount of nitrogen element, as long as the gas has a lower nitrogen element content than at least air, it is compared with the gas whose atmosphere is air. What can perform wavelength conversion with high output 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 a further test in order to investigate the cause of deterioration of the wavelength conversion characteristics using the CLBO crystal. For example, when the wavelength converter 7b shown in Example 2 is used, a CLBO crystal is used as the nonlinear optical crystal 2, a laser beam having a wavelength of 532 nm is incident on the CLBO crystal, and converted into an ultraviolet laser beam having a wavelength of 266 nm, the gas 16 When a CLBO crystal was placed in an oxygen (O ₂ ) atmosphere and a continuous ultraviolet laser beam generation test was conducted using oxygen gas (volume content: 99.7%) as a wavelength of 532 nm for the CLBO crystal There was no change in the laser beam incident end face before the start of the test, but there was a case where discoloration was observed in the laser beam passing part of the 266 nm wavelength UV laser beam emitting end face of the CLBO crystal. There was no change except for the passing portion, and the output could be kept at 20W. In addition, when argon gas (volume content: 99.9%) was used as the gas 16 and the CLBO crystal was placed in an argon gas (Ar) atmosphere and an ultraviolet laser beam generation test was performed, Although discoloration was observed at the laser beam passage end portion of the laser beam incident end face having a wavelength of 532 nm, there was a case where the UV laser beam emitting end face of the CLBO crystal had no change from before the test was started.

Therefore, when a CLBO crystal is used as the nonlinear optical crystal 2, the atmosphere in contact with the emission surface of the CLBO crystal at a wavelength of 266 nm ultraviolet laser beam is a gas having a smaller nitrogen element content than air and a gas other than oxygen, such as argon gas ( A gas atmosphere mainly composed of Ar), and an 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, an atmosphere such as a gas mainly composed of oxygen gas (O ₂ ) or air. As a result, the interaction between the nonlinear optical crystal 2 and the atmosphere can be more reliably prevented, so that a high-quality and high-power wavelength conversion laser beam can be generated more stably for a longer period of time. The nonlinear optical crystal 2 includes crystals containing cesium such as cesium lithium borate (chemical formula: CsLiB ₆ O ₁₀ , abbreviation: CLBO) crystal and cesium borate (chemical formula: CsB ₃ O ₅ , abbreviation: CBO) crystal. Are suitable for 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 oxy. Even if it is a crystal not containing cesium such as a borate (chemical formula: Gd _x Y _1-x , Ca ₄ (BO ₃ ) ₃ , abbreviation: GdYCOB) crystal, an element other than cesium reacts with nitrogen to form a nitrogen compound. There is a possibility that it can be used.

  Further, in the fourth embodiment, the example in which the plugs 14a, 14b, 14c, and 14d are opened and the gases 16a and 16b are always flowed has been described. However, the space in the container 11 that is in contact with the incident end face of the nonlinear optical crystal 2 and After the contacting spaces are filled with the gas 16a and the gas 16b, respectively, the stoppers 14a, 14b, 14c and 14d are closed so that the gas 16a and the gas 16b are sealed in the respective spaces in the container 11, that is, the nonlinear optical crystal 2 May be used as a sealed cell, which has the same effect as in Example 4. However, in this case, the effect due to the circulation of the gases 16a and 16b cannot be obtained.

  Embodiment 5 FIG.

  FIG. 7 is a view for explaining a wavelength conversion method and a wavelength conversion apparatus according to Embodiment 5 for carrying out the present invention, and more specifically, is a longitudinal sectional view of the wavelength conversion apparatus.

  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 thing and performs the same action. 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. Reference numeral 46 denotes an angle adjuster corresponding to a means for adjusting the angle of the nonlinear optical crystal 2 with respect to the incident light. 47 is a position adjuster corresponding to means for adjusting the passing position of incident light in the nonlinear optical crystal 2. 7e shows the whole wavelength converter.

  An optical window 3a, 3b, O-rings 4a, 4b, and stoppers 14a, 14b are attached to the container 11a, and a laser beam is passed through the nonlinear optical crystal 2 through the optical windows 3a, 3b while the lid 11b is opened. The angle of the nonlinear optical crystal 2 with respect to the laser beam is adjusted by the adjuster 46, and the laser beam passing position of the nonlinear optical crystal 2 is adjusted by the position adjuster 47, whereby the output of the wavelength converted laser beam generated by the nonlinear optical crystal 2 is obtained. Is adjusted to 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) in the component or containing little nitrogen element, the container 11a is filled with the gas 16 containing no nitrogen element (N) in the component or containing little 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. For example, as described in the fourth embodiment, oxygen 16 is used as the gas 16. When a gas mainly composed of gas or argon gas is used and operated at a high output for a long time, discoloration occurs in the laser beam emission end face of the CLBO crystal which is the nonlinear optical crystal 2 or the laser beam passing part of the incident end face. In such a case, the wavelength 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 thereby reduce the 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 deteriorates, and the life of the nonlinear optical crystal 2 is substantially extended. An effect that can be.

  Further, as in the case of Example 1, the nonlinear optical crystal 2 is exposed to the gas 16 that does not contain nitrogen element or has a small amount of nitrogen element. Therefore, the wavelength of the laser beam is converted to a wavelength of 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, impurities are not generated from the container, and a long period of time is maintained. There is an effect that a wavelength conversion laser beam having high quality and high output can be stably generated. Further, as in the case of Example 2, the heating element 18 and the heat insulating material 19 are provided, and the gas 16 contains a small amount of moisture by keeping the nonlinear optical crystal 2 at a constant temperature of 100 ° C. or higher. Even in this case, since the nonlinear optical crystal 2 does not absorb moisture, the wavelength conversion laser beam can be generated stably for a long period of time.

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

  Example 6

  FIG. 8 is a view for explaining a wavelength conversion method and a wavelength conversion apparatus according to Embodiment 6 for carrying out the present invention. More specifically, FIG. 8 is a longitudinal sectional view of the wavelength conversion apparatus.

  In FIG. 8, 2, 3a, 3b, 4a, 4b, 11, 12a, 12b, 13a, 13b, 14a, 14b, 15a, 15b, 16a, 16b, 17c, 17d, 18, 19 are the same as those in the fourth embodiment. It is the same as shown and performs the same function. 13 e and 13 f are holes formed in the container 11. 14e and 14f are stoppers. 15e and 15f are pipes. 15 g is a pipe, which corresponds to means for supplying a gas having a nitrogen element content smaller than air to the vicinity of the emitting end face of the nonlinear optical crystal 2. The pipe 15 g is connected to a hole 13 e that puts the gas 16 b 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 shows the whole wavelength converter. Although not clearly shown in FIG. 8, the space in contact with the incident end face of the nonlinear optical crystal 2 and the space in contact with the exit end face in the container 11 are separated by, for example, a partition wall. This is the same as the case of 4.

  Both ends of the nonlinear optical crystal 2 are cut and polished at a phase matching angle for generating an ultraviolet laser beam having a wavelength of 400 nm or less by wavelength conversion, and 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 the atmosphere in contact with the incident end face of the nonlinear optical crystal 2 is the atmosphere of the gas 16a. It is discharged out of the container 11 through 13a, the stopper 14a, and the pipe 15a. The gas 16b flows at a predetermined flow rate (for example, a flow rate of 0.1 liter / min) from the pipe 15e through the plug 14e, the hole 13e, and the pipe 15g to the vicinity of the emission end face of the nonlinear optical crystal 2 in the container 11. The atmosphere in contact with the emission end face of the optical crystal 2 is the atmosphere of the gas 16b, and 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, connected to a pipe 15e from a gas cylinder not shown in the figure, through a flow rate adjustment valve not shown in the figure, and further through a flow meter not shown in the figure. Is adjusted by adjusting 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 also be obtained. That is, since the gas 16b is caused to flow in the vicinity of the exit end face of the nonlinear optical crystal 2, even if impurities are generated from the constituent material in the container 11 or the like, it has just flowed into the exit end face of the nonlinear optical crystal 2. Since the fresh gas 16b is supplied, it is possible to prevent impurities from adhering to the exit end face of the nonlinear optical suspension 2, and further, to prevent adhesion from adhering to the portion of the optical window 3b close to the nonlinear optical crystal 2 and stable for a long time. In addition, the effect of generating a high-quality and high-output wavelength conversion laser beam is enhanced. In addition, since the hole 13f is provided at a position facing the pipe 15g that is the inlet of the gas 16b into the container 11 with the nonlinear optical crystal 2 interposed therebetween, impurities are generated from the components in the container 11 and the like. However, since the impurities can be efficiently removed from the inside of the container 11, it is possible to prevent the impurities from adhering to the emission end face of the nonlinear optical crystal 2 and the optical window 3b, and to stably provide a high quality and high output wavelength conversion laser for a long period of time. The effect that a beam can be generated is further enhanced.

  In the above-described embodiment 6, 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, Even if impurities are generated from the constituent material, it is possible to more reliably prevent the impurities from adhering to the exit end face of the nonlinear optical crystal 2 or the portion of the optical window 3b close to the nonlinear optical crystal 2, and to stably provide high quality over a long period of time. The effect of being able to generate a high-power wavelength-converted laser beam is further enhanced.

  Further, in Example 6 described above, the gas 16b is caused to flow into the vicinity of the end face of the nonlinear optical crystal 2 only on the exit end face side of the nonlinear optical crystal 2 and is efficiently discharged from the hole 13f facing the inflow port 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 material in the container 11, the impurities are incident on the incident end face of the nonlinear optical crystal 2 or the nonlinear optics of the optical window 3 a. The effect of preventing the adhesion to the portion close to the crystal 2 and generating a wavelength conversion laser beam with high quality and high output stably for a longer period of time can be further enhanced.

  In the sixth embodiment, the case where the pipe 15g is used as the 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 is shown. 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 directly from the holes 13b and 13e to the vicinity of the end face of the nonlinear optical crystal 2 without using the pipe 15g. The same effect as in Example 6 is obtained.

  Example 7

  In the sixth embodiment, as described in the fourth embodiment, the wavelength conversion method for converting the wavelength of the atmosphere in contact with the incident end face of the nonlinear optical crystal 2 and the atmosphere in contact with the exit end face into gases 16a and 16b having different components. In the wavelength conversion device, the description has been given of the case where the gas having a nitrogen element content smaller than air is supplied to the vicinity of the incident end face or the exit end face of the nonlinear optical crystal 2 and then discharged. However, the present invention is not limited to this. For example, as described in the first to third embodiments and the fifth embodiment, the wavelength that converts the wavelength of the atmosphere in contact with the incident end face of the nonlinear optical crystal 2 and the atmosphere in contact with the exit end face into the gas 16 of the same component. In the conversion method and the wavelength conversion device, after supplying the gas 16 having a nitrogen element content smaller than air to the vicinity of the incident end face or the exit end face of the nonlinear optical crystal It may be discharged.

  FIG. 9 is a view for explaining a wavelength conversion method and a wavelength conversion apparatus according to Embodiment 7 for carrying out the present invention. More specifically, FIG. 9 is a longitudinal sectional view of the wavelength conversion apparatus.

  In FIG. 9, 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 thing and performs the same action. 15 g is a pipe similar to that described in Example 6, and corresponds to a means for supplying a gas 16 having a nitrogen element content smaller than air to the vicinity of the exit end face of the nonlinear optical crystal. 7g shows the wavelength converter full holiday.

  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 16 is emitted at a predetermined flow rate (for example, a flow rate of 0.1 liter / min) from the pipe 15b through the plug 14b, the hole 13b, and the pipe 15g connected to the hole 13b. The atmosphere flowing into the vicinity and in contact with the emission end face of the nonlinear optical crystal 2 is the atmosphere of the gas 16, and is discharged out of the container 11 through the hole 13 a, the plug 14 a, and the pipe 15 a. The flow rate of the gas 16 is, for example, connected to a pipe 15b from a gas cylinder not shown in the figure, through a flow rate adjustment valve not shown in the figure, and further through a flow meter not shown in the figure. Is adjusted by adjusting and is measured by a flow meter.

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

  That is, since the gas 16 is allowed to flow in the vicinity of the exit end face of the nonlinear optical crystal 2, even if impurities are generated from the constituent material in the container 11, the gas 16 has just flowed into the exit end face of the nonlinear optical crystal 2. Since the fresh gas 16 is supplied, it is possible to prevent impurities from adhering to the exit end face of the nonlinear optical crystal 2, and further to prevent the impurities from adhering to the portion of the optical window 3 b close to the nonlinear optical crystal 2, and stably for a long period of time. The effect of being able to generate a wavelength conversion laser beam with high quality and high output is enhanced.

  Moreover, in the said Example 7, although the example which flows the gas 16b with the flow volume of 0.1 liter / min was demonstrated, by increasing the flow volume to 1 liter / min and further to 10 liter / min, temporarily in the container 11 inside. Even if impurities are generated from the constituent material, it is possible to more reliably prevent the impurities from adhering to the exit end face of the nonlinear optical crystal 2 or the portion of the optical window 3b close to the nonlinear optical crystal 2, and to stably provide high quality over a long period of time. The effect of being able to generate a high-power wavelength-converted laser beam 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 Example 7, the same wavelength converter as described in Example 2 is provided with means (pipe 15g) for supplying the gas 16 in the container 11 to at least the vicinity of the emission end face 10 of the nonlinear optical crystal 2. However, the present invention is not limited to this, and the same wavelength converter as described in the first, third, or fourth embodiment is used. A means (pipe 15g) for supplying the vicinity may be provided, and in this case, the same effect can be obtained.

  In Example 7, the case where the pipe 15g is used as a means for supplying the gas 16 to the vicinity of the incident end face or the exit end face of the nonlinear optical crystal 2 in the container 11 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 directly from the holes 13b and 13e to the vicinity of the end face of the nonlinear optical crystal 2 without using the pipe 15g. The same effect as in Example 7 can be obtained.

  Example 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. More specifically, FIG. 10 is a longitudinal sectional view of the wavelength conversion laser device.

  In FIG. 10, 2 is a nonlinear optical crystal. Reference numeral 7a denotes the wavelength converter shown in the first embodiment. A laser device 20 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. A laser beam 21 a is obtained by converting a part of the laser beam 21 having a wavelength of 532 nm into a wavelength of 266 nm by the nonlinear optical crystal 2. Reference numeral 22 denotes a wavelength selective mirror with a coating that transmits a laser beam having a wavelength of 266 nm and reflects the laser beam having a wavelength of 532 nm. 21b is an ultraviolet laser beam having a wavelength of 266 nm. Reference numeral 23 denotes a base. Reference numeral 24 denotes a fixing base for fixing the wavelength conversion device 7 a 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.

Non-linear 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, 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 , abbreviated as GdYCOB) crystal, and both end faces are cut and polished at a phase matching angle for generating an ultraviolet laser beam having a wavelength of 400 nm or less by wavelength conversion, and fixed by fixtures 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 enters the wavelength conversion device 7a, and a part of the wavelength 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 through the wavelength selection mirror 22 only with a wavelength of 266 nm component and reflected with a wavelength of 532 nm component, so that an ultraviolet laser beam 21b with a wavelength of 266 nm is obtained.

  In Example 8, the wavelength conversion laser device is configured as described above, and the nonlinear optical crystal 2 is exposed to a gas that does not contain nitrogen element or contains little nitrogen element. As a result, a nitric acid compound such as cesium nitrate is not generated even when irradiated with an ultraviolet laser beam having a wavelength of 400 nm or less by wavelength conversion, so that a high-quality and high-power wavelength-converted laser beam is generated stably for a long period of time. There is an effect that can be. Further, since the wavelength conversion device 7a does not need to be a vacuum vessel, impurities are not generated from the vessel, and the wavelength conversion laser device can be provided at low cost.

  In addition, in the said Example 8, although it showed about the example using the wavelength converter 7a shown in Example 1, you may use any wavelength converter 7b-7g shown in Examples 2-7, The same effects as those of the eighth embodiment are achieved.

Further, in the embodiment 8, neodymium-YAG example using _{(Nd: Y 3 Al 5 O} 12: YAG, chemical formula _Nd) laser device 20 for generating a laser beam having a wavelength of 532nm which is a second harmonic of the laser as the light source However, the wavelength of the light source is not limited to this. For example, ytterbium yag (Yb: YAG, chemical formula Yb: Y ₃ Al ₅ O ₁₂ ), neodymium irf (Nd: YLF, chemical formula Nd: LiYF ₄ ) The fundamental wave, second harmonic wave, or the like of neodymium / wiviophore (Nd: YVO ₄ ), titanium sapphire (Ti: Al ₂ O ₃ ), and the same effects as those of the eighth embodiment can be obtained.

  Example 9

  FIG. 11 is a view for explaining a laser beam machine according to Embodiment 9 for carrying out the present invention, and 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. Reference numeral 27 denotes a galvanometer mirror. Reference numeral 28 denotes a galvanometer mirror fixing jig for fixing the galvanometer mirror 27 at a variable angle with respect to the ultraviolet laser beam 21 b having a wavelength of 266 nm emitted from the wavelength conversion laser device 26. Reference numeral 29 denotes 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, and here, a glass epoxy printed board. Reference numeral 33 denotes a processing machine base. A processing machine 34 includes a galvano mirror 27, a galvano 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 galvano mirror 27 is fixed to a mirror lens fixing jig 31 by a galvano mirror fixing jig 28 and fixed on a processing machine base 33. The fθ lens 29 is fixed to the mirror lens fixing jig 31 by the fθ lens fixing jig 30 and fixed on the processing machine base 33.

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

  In the ninth embodiment, the laser beam machine is configured as described above, and the wavelength conversion laser device 26 can generate the wavelength conversion laser beam 21b stably for a long period of time, so that it can be stably and accurately uniform for a long period of time. The manufacturing method of the printed circuit board which produces the effect that it can be processed easily and has good quality is provided. Moreover, since the wavelength converter 7a does not need to be a vacuum vessel, the laser processing machine can be provided at a low cost.

  In FIG. 11, the galvano mirror 27 is provided and the traveling direction of the wavelength conversion laser beam 21b is variably changed. However, the movable base for moving the workpiece 32 such as the XY stage on the base 33 is shown. In addition, both the galvanometer mirror 27 and the movable base may be provided.

  Moreover, although what provided the f (theta) lens 29 was shown, you may provide a plano-convex lens, a biconvex lens, etc. FIG.

  In the above-mentioned embodiment 9, an example of processing for making a hole in a workpiece 32 made of a glass epoxy printed board has been shown. However, the workpiece 32 may be a printed board of other materials, a green sheet, an electronic component, metal, glass, etc. Any material may be used as long as it is a processing target, and any processing such as cutting, welding, engraving, marking, formation, etc. may be used for the processing. Has the same effect as.

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

  The wavelength conversion method and the wavelength conversion apparatus according to the present invention can be used for, for example, a wavelength conversion laser apparatus, and a laser processing machine can be configured using the wavelength conversion laser apparatus. Such a laser processing machine can be used for various processes such as the manufacture of a printed circuit board and the manufacture of a fiber grating, for example, because it can perform uniform processing stably and accurately over a long period of time.

It is a longitudinal cross-sectional view of the wavelength converter by Example 1 of this invention. It is a longitudinal cross-sectional view of the wavelength converter by Example 1 of this invention. It is a longitudinal cross-sectional view of the wavelength converter by Example 2 of this invention. It is a longitudinal cross-sectional view of the wavelength converter by Example 2 of this invention. It is a longitudinal cross-sectional view of the wavelength converter by Example 3 of this invention. It is a longitudinal cross-sectional view of the wavelength converter by Example 4 of this invention. It is a longitudinal cross-sectional view of the wavelength converter by Example 5 of this invention. It is a longitudinal cross-sectional view of the wavelength converter by Example 6 of this invention. It is a longitudinal cross-sectional view of the wavelength converter by Example 7 of this invention. It is a longitudinal cross-sectional view of the wavelength conversion laser apparatus by Example 8 of this invention. It is a longitudinal cross-sectional view of the laser processing machine by Example 9 of this invention. It is a longitudinal cross-sectional view of the conventional wavelength converter.

Explanation of symbols

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

Claims (14)

  In the wavelength conversion method for converting the wavelength of light through a nonlinear optical crystal, the nonlinear optical crystal contains cesium, and the atmosphere in contact with the surface from which the wavelength-converted light of the nonlinear optical crystal is emitted is mainly composed of carbon dioxide gas. A wavelength conversion method characterized by converting the 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.   The wavelength according to claim 1, wherein the wavelength conversion is performed by covering the incident end face on which the wavelength-converted light of the nonlinear optical crystal is incident and the exit end face on which the wavelength-converted light is emitted with the gas. Conversion method.   Wavelength conversion is performed by converting the atmosphere in contact with the incident end face on which the wavelength-converted light of the nonlinear optical crystal is incident and the atmosphere in contact with the exit end face from which the wavelength-converted light is emitted into the gas having different components. 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 discharged after being supplied to at least the vicinity of the emitting end face of the nonlinear optical crystal.   In the wavelength conversion device for converting the wavelength of light through the nonlinear optical crystal, the nonlinear optical crystal contains cesium, and the atmosphere in contact with the surface from which the wavelength-converted light of the nonlinear optical crystal is emitted is mainly composed of carbon dioxide gas. A wavelength conversion device comprising means for converting the gas into a gas.   8. The wavelength conversion device according to claim 7, wherein the wavelength-converted light having an average power of 5 W or more is emitted.   The wavelength conversion device 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 according to claim 7, further comprising means for covering the incident end face on which the wavelength-converted light of the nonlinear optical crystal is incident and the exit end face from which the wavelength-converted light is emitted with the gas. apparatus.   Characterized in that it comprises means for making the atmosphere of the nonlinear optical crystal in contact with the incident end face where the wavelength-converted light is incident and the atmosphere in contact with the exit end face where the wavelength-converted light is emitted into the gas having different components. The wavelength conversion device according to claim 7.   The wavelength converter 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 opening through which incident light and outgoing light partially pass, and supplying the gas in the container to at least the vicinity of the exit end face of the nonlinear optical crystal; The wavelength converter according to claim 12, further comprising means for discharging the supplied gas from the container. A laser device as a light source of the wavelength conversion include nonlinear optical crystal of cesium, the atmosphere in which the light whose wavelength is converted in a nonlinear optical crystal is in contact with the surface to be emitted, means for a gas consisting mainly of carbon dioxide gas the provided laser processing machine characterized by comprising a wavelength conversion laser device having a wavelength converter for wavelength-converting the laser light through the nonlinear optical crystal from the laser device.

Images