JP2007123322A - Laser device and method of operating same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laser device where harmful gas which occurs in a cabinet and deteriorates an optical component can be removed with a simple structure, and to provide a method of operating the laser device. <P>SOLUTION: The laser device is provided with a laser oscillator radiating a laser beam and the cabinet incorporating the laser oscillator. A photocatalyst is installed in a part in the cabinet where scattered light or partial reflected light of the laser beam is irradiated from the laser oscillator. When TiO<SB>2</SB>is used as the photocatalyst, harmful gas is decomposed to a harmless level by mainly irradiating ultraviolet light of 380 nm or less. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a laser device and a method for operating the laser device, and more particularly to a laser device provided with a photocatalyst for decomposing a gas that degrades optical components in a casing constituting the laser device, and a method for operating the laser device.

  As the life of the laser is extended, the laser generating means is changing from gas to solid. When generating light with high photon energy or pulsed light with high peak value, the surface of a laser gain medium, nonlinear optical crystal, lens, mirror, etc. (collectively optics), or various types on the surface The coating may be damaged. One cause of this damage is the toxic gas in the atmosphere. R.I. published in US SPIE conference proceedings (Volume 4000, pages 474-487, 2000). R. The paper “Experimentation and Modeling of Organic Photocontamination on Lithographic Optics” by Kunz et al. Mentions organic gas as a cause of damage to optics transmitting ultraviolet light. Examples of a laser device that generates coherent light having a large photon energy include laser devices that generate second, third, and fourth harmonics of a fundamental wave having a wavelength of about 1 μm extracted from a neodymium-doped crystal as laser light. . The operation mode includes pulse and continuous oscillation. Damage caused by the interaction between organic gas and light is a problem on the surface of optics in such a laser device. In the case of a laser device that generates the third harmonic, the wavelength is 355 nm, but damage often occurs on the surface of the nonlinear optical crystal LBO that generates this light.

  For a laser apparatus that is used in the industrial field and generates laser light or coherent light that is the second or third harmonic of the laser light, it is desired that the maintenance time interval is long. As described above, a harmful gas that damages the optical component or degrades the performance of the optical component is present in the casing that is the light generation unit. In particular, optical components on the laser optical axis such as resonator mirrors, laser oscillation medium surfaces, and nonlinear optical crystals tend to be damaged in a short time. Examples of the harmful gas include water vapor or organic gas emitted from an optical component, an optical component mount, an electric / electronic component, or a container itself. When light is generated in the presence of this gas, particularly when the wavelength is included in the ultraviolet wavelength region, the gas is decomposed by light or heat, and the decomposition product adheres to the optical component. When the light is absorbed, the adhering matter is excited, heated, etc., so that the optical parts are irreversibly damaged, and the laser apparatus needs to be frequently maintained.

  In order to solve the above problems, the conventional apparatus employs a structure in which an inert gas having a high purity is introduced from the outside to expel harmful gases from the housing. In the field of projection exposure equipment that uses laser light sources in the vacuum ultraviolet region, photocatalysts are used to prevent optical component contamination by harmful gases and optical performance degradation due to absorption of laser light at the contaminated site. It has been proposed to do. By causing the harmful gas released to act on the photocatalyst irradiated with ultraviolet rays, the harmful gas can be decomposed into another gas molecule and absorbed and removed to make it harmless. Further, in the field of exposure steppers for semiconductor devices, an apparatus for removing organic gas has been proposed in order to protect the optics on the light transmission path inside the apparatus.

  In order to ensure the stability of the laser oscillator, even in a laser apparatus having a structure in which an inert gas is sealed in a housing incorporating the laser oscillator, harmful gas is mixed into the gas in the sealed housing. When a powerful laser beam generated by laser oscillation acts on the harmful gas, the gas changes to cause the surface deterioration of the optical component. For this purpose, a laser apparatus having a structure in which gas is sucked from a casing, the sucked gas is guided to a catalyst to decompose and remove harmful gases, and the filtered gas is returned into the casing is disclosed in US Pat. , 671,303 specification.

US Pat. No. 6,671,303 JP 2003-45787 A JP 2002-319540 A

  In the above prior art, since it is necessary to form a gas circulation system that sucks harmful gas generated in the housing of the laser device and passes the catalyst through the catalyst, and then returns the gas to the inside of the housing. There is a problem that the configuration is complicated and the manufacturing cost is high.

  The present invention has been made in order to solve the above-described problems, and an object of the present invention is to provide a laser device capable of removing harmful gas generated in a housing with a simple configuration and a method for operating the laser device. To do.

  The organic gas is originally present in the casing constituting the laser apparatus or is generated from components installed in the casing. Examples of such a generation source include an electrically insulating polymer material and a lead wire coating material for electronic parts. Regarding the mechanism of the optics damage, the organic gas is activated by absorbing ultraviolet light, and reacts with the optics surface to generate deposits, which may damage the coating. Therefore, it is necessary to change the organic gas to one that does not decompose even when absorbing high-energy photons such as ultraviolet light or laser light having a high peak value of pulse output. As a method for this, a photocatalyst is disposed in a housing of a laser device, and the photocatalyst is irradiated with scattered light or partially reflected light associated with high-energy photons or pulsed light, thereby decomposing the organic gas and making it harmless. For example, a photocatalyst is disposed in the vicinity of the laser light output window. In addition, a photocatalyst is disposed at a portion irradiated with laser light branched (partially reflected) by a branching means such as a beam splitter. Further, instead of or simultaneously with the irradiation with the scattered light or the partially reflected light relating to the laser light, the photocatalyst is irradiated with ultraviolet rays output from an ultraviolet irradiation device provided separately from the laser oscillator. In the case of adopting such a configuration, an operation method is employed in which the photocatalyst is irradiated with ultraviolet rays output from the ultraviolet irradiation device to remove harmful gases existing in the housing before the laser beam is emitted from the laser oscillator. Is preferred.

Titanium oxide TiO ₂ is suitable as a material employed as the photocatalyst. By using TiO ₂ as a medium, oxygen and water are activated by light energy, and the organic gas is decomposed. FIG. 1 is a diagram for explaining decomposition of an organic gas by a photocatalyst. TiO ₂ is a semiconductor material, and its energy gap is approximately 3.2 eV. The wavelength of light corresponding to this band gap is 387 nm, and light can be excited if the wavelength is shorter than the wavelength. When the light wavelength is long, the photon energy is small, but in the pulse mode, it can be excited by a nonlinear phenomenon based on multiphoton absorption. In this case, it is desirable to activate TiO ₂ by irradiating laser light partially reflected by the branching means rather than irradiating scattered light. On the excited TiO ₂ surface, as shown in FIG. 1, when the organic gas is a hydrocarbon-based material, the organic gas is oxidized by the catalytic action, and finally the hydrocarbon-based intermediate product and CO ₂ is produced. About an intermediate product, decomposition | disassembly is repeated so that molecular weight may become small, and it will generally make it harmless. Since the decomposed CO ₂ is removed by an adsorbent or the like, activation by light is less likely to occur, and the influence on optics can be nullified.

Further, in order to remove the intermediate product that has not been decomposed to CO ₂ , the adsorbing means having an adsorbent that adsorbs these lower hydrocarbon products (impurities), water, etc. is sealed in a sealed casing. Install in. Examples of water adsorbents include silica gel and zeolite, and examples of adsorbents for organic substances (organic substances and organic substances that have not been sufficiently decomposed) include activated carbon and zeolite. These adsorbents are accommodated in a container such as a net and are installed in the casing of the laser device. In a case where the laser oscillator is hermetically sealed, the nonlinear optical element may be used while being controlled at a temperature higher than room temperature. In such a case, gas convection occurs due to the existence of a heat generation source inside the housing of the laser device. If an adsorbing means is installed on the flow path of the convection gas, it is possible to efficiently adsorb harmful gas. Moreover, it is good also as a structure which provides the circulation means given as a circulation fan etc. and forcibly circulates gas. The decomposed organic gas or the like can be removed by the filter action of the adsorption means.

  According to the present invention, since the photocatalyst is installed at the site in the casing irradiated with the scattered light or the partially reflected light of the laser beam emitted from the laser oscillator, the organic gas present in the casing is low in level. It is decomposed into organic substances. As a result, carbon and soot generated by the direct decomposition of organic gas by laser light can be prevented from adhering to the optical component, so that damage to the surface of the resonator component such as a mirror and the nonlinear optical crystal is caused by the deposit. Can be reduced. That is, it is possible to remove harmful gases that damage optical components by a simple structure in which the photocatalyst is installed in the housing. In addition, since the occurrence of damage to optical components can be reduced, stable laser oscillation can be continued for a long time by the laser device having the simple structure as described above, and the maintenance frequency of the laser device can be reduced. Has the effect of becoming.

  According to the present invention, since the photocatalyst is installed in a portion around the optical axis of the laser output window for outputting laser light from the laser device or a portion in the vicinity of the laser output window, it is emitted from the laser oscillator. Since more scattered light of the laser beam can be received by the photocatalyst, the decomposition efficiency of the organic gas by the photocatalyst is improved, and the occurrence of damage to the optical component can be further reduced.

  According to the invention of the present application, it has a branching means for branching the laser light emitted from the laser oscillator, and the photocatalyst is installed at the site irradiated with the laser light partially reflected by the branching means. It is possible to increase the power density of the laser beam irradiated to the photocatalyst, and even if the wavelength of the laser beam is longer than the absorption wavelength of the photocatalyst, photoexcitation occurs based on the nonlinear effect and activates the catalytic action. Can do. As a result, even for a laser device incorporating a laser oscillator in which the wavelength of the laser light is outside the ultraviolet wavelength region, it is possible to reduce the occurrence of damage to the optical components.

  According to the present invention, since it is configured to have an ultraviolet irradiation device that can operate independently of the laser oscillator and irradiates the photocatalyst with ultraviolet rays, the organic gas can be decomposed using the photocatalyst even when the oscillation of the laser oscillator is stopped. Since organic gas can be decomposed and removed before the laser oscillator is driven, it is possible to prevent carbon and other particles from adhering to the optical component and reduce the occurrence of damage to the optical component. There is an effect that can be done.

  According to the present invention, since it has an adsorption means for adsorbing at least the gas decomposed by the photocatalyst, it is possible to substantially remove harmful gases including organic gas, and further reduce the occurrence of damage to optical components. There is an effect that can be done.

  According to the present invention, since the adsorbing means or the photocatalyst is configured to be installed in the vicinity of the heat source existing in the casing, gas convection is generated in the casing due to heat generation of the heat source, and convection occurs. By arranging the adsorption means or photocatalyst in the gas flow path, decomposition and removal of harmful gases are promoted and the removal efficiency of harmful gases is improved, so that the occurrence of damage to optical components can be further reduced. There is an effect.

  According to the present invention, since it is configured to have a circulation means for forcibly circulating the gas existing in the casing, the adsorption means or the photocatalyst is disposed in the gas flow path, so that the harmful gas is decomposed and removed, etc. Is promoted and the removal efficiency of harmful gas is improved, so that the occurrence of damage to optical components can be further reduced.

  According to the present invention, the laser light output from the laser device is pulse light, and the pulse width of the laser light is 1 microsecond or less. Even in laser devices where the surface part of conventional optical components has been damaged early, stable laser oscillation can be continued for a long time using a simple structure. There is an effect that it can be greatly reduced.

  According to the present invention, the laser oscillator is driven at a low output, and the laser oscillator is driven at a high output after a predetermined time has elapsed. Since the harmful gas can be decomposed and removed by the photocatalyst while the photochemical action of the laser is small, the occurrence of damage to the optical components can be further reduced as compared with the case where the laser oscillator is driven at a high output from the beginning. There is an effect.

  According to the present invention, the ultraviolet light irradiation device is driven to irradiate the photocatalyst with ultraviolet light, and the laser oscillator is driven after a predetermined time has elapsed, so the harmful gas is decomposed by the photocatalyst irradiated with the ultraviolet light. Since the laser oscillator is driven after the removal, there is an effect that the occurrence of damage to the optical component can be further reduced as compared with the case where the laser oscillator is driven from the beginning.

Embodiments according to the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 2 is a diagram showing the configuration of the laser apparatus according to Embodiment 1 of the present invention. The housing 10 constituting the laser device is provided with a laser output window 14 made of a laser light transmitting material. The solid-state laser oscillation medium 1 is installed inside the housing 10, and the first resonator mirror 2 and the second resonator mirror constituting the resonator are disposed on both sides of the laser oscillation medium 1 along the optical axis 21. 3 are arranged so as to face each other. The first resonator mirror 2 has a characteristic that substantially totally reflects the light having the wavelength of the oscillation light and shows transparency to the light having the wavelength of the excitation light. The second resonator mirror 3 reflects light with a high reflectivity with respect to light having the fundamental wavelength of laser oscillation and transmits light with light having the second harmonic wavelength. It has the characteristic which shows.

  Between the resonator mirror 3 and the laser oscillation medium 1, a Q switch element 7 and a harmonic generation element 8 made of a nonlinear optical crystal are arranged. On the side opposite to the laser oscillation medium 1 with respect to the resonator mirror 2, a semiconductor laser 4 for optical excitation is disposed. The excitation light output from the semiconductor laser 4 is converged by the condenser lens 5, passes through the resonator mirror 2, enters the laser oscillation medium 1, and excites the laser oscillation medium 1. The optically excited laser oscillation medium 1 outputs a fundamental laser beam by stimulated emission. A fundamental laser beam oscillates between the resonator mirror 2 and the resonator mirror 3 via the laser oscillation medium 1 having an amplification gain. The excitation light also diverges outside the optical axis, as indicated by the broken line 9. By using the condensing lens 5 to condense the excitation light toward the central axis of the laser oscillation medium 1 again, efficient optical excitation is realized and the oscillation output is improved.

  When a fundamental laser beam oscillated between the resonator mirror 2 and the resonator mirror 3 passes through the Q switch 7 for pulse control and enters the harmonic generation element 8 that doubles the frequency of the fundamental wave. A double wave of the fundamental wave is generated. The second harmonic laser beam is transmitted through the resonator mirror 3 and emitted outside the resonator. When this second harmonic laser beam is made of a nonlinear optical crystal and enters the harmonic generation element 11 that doubles the frequency of the second harmonic, a fourth harmonic of the fundamental wave is generated. The fourth harmonic laser beam emitted from the harmonic generation element 11 passes through the laser output window 14 and is output to the outside of the housing 10 as an output beam.

In the present invention, a photocatalyst 13 provided as, for example, titanium oxide TiO ₂ is radiated from a laser oscillator including the laser oscillation medium 1, the resonator mirrors 2 and 3, the harmonic generation elements 8 and 11, etc. in the housing 10. It is installed at a site irradiated with scattered light 15 or partially reflected light related to the laser light. The photocatalyst 13 is disposed, for example, at a site around the optical path of the laser beam, particularly at a site around the optical axis on the laser output window 14 or a site near the laser output window 14. Moreover, the structure which arrange | positions the photocatalyst 13 in the cavity pipe | tube covering the optical path periphery of a laser beam can also be taken.

  In the housing 10, apart from the photocatalyst 13, an adsorbing means 16 equipped with an adsorbent of decomposition products generated by the photocatalyst is installed. This adsorbing means 16 uses an adsorbent of water using silica gel, zeolite, etc. and an absorbent of organic substances (organic substances and organic substances that have not been sufficiently decomposed) using activated carbon, zeolite, etc. Consists of housing. Further, it is preferable to configure the adsorption means 16 so as to have a structure in which gas can freely flow from the outside. Furthermore, an electric furnace 12 that controls the temperature of the crystal so that the crystal temperature becomes an optimum temperature higher than room temperature is installed in the housing 10 in order to increase the wavelength conversion efficiency of the nonlinear optical crystal.

  A Peltier element is used to adjust the temperature of the nonlinear optical crystal. The lead wire of the Peltier element is covered with an electrically insulating polymer. Also for the Peltier element itself, an adhesive is used to bond the semiconductor element to the ceramic substrate. These lead wires and adhesives generate hydrocarbon-based harmful gases. In order to perform a pulse operation, a Q switch element is installed in the laser oscillator. Harmful gas is also generated from the covering material or adhesive material of the lead wire connected to the Q switch element. If the harmful gases are not removed, the hydrocarbon-based harmful substances are photodegraded as they are, and damage is caused by carbon particles adhering to the coating on the surface of a nonlinear optical crystal (LBO) or the like that generates a harmonic beam. Will do.

  Since harmful gas such as organic gas has a low concentration, the high speed of decomposition by the photocatalyst is not so required. Gas convection occurs in the vicinity of a heat source such as the electric furnace or temperature control element as described above. Therefore, by installing a photocatalyst or an adsorbent on the gas flow path that convects in the housing, it is possible to decompose or remove a trace amount of harmful gas. Thereby, with a simple structure, stable laser oscillation can be sustained for a long time, and a practical effect is great. Further, a circulation means for forcibly flowing the gas may be provided.

  In the laser oscillator having the above-described configuration, the pumping light 9 is irradiated from the pumping semiconductor laser 4 to the laser oscillation medium 1 having a laser amplification gain. The fundamental laser beam radiated from the excited laser oscillation medium 1 is controlled by the Q switch element 7 between the resonator mirror 2 and the resonator mirror 3 to generate pulse oscillation. The fundamental laser beam is converted to a second harmonic by the harmonic generation element 8 and further converted to a fourth harmonic by the harmonic generation element 11. If the wavelength of the fundamental wave is 1.06 μm, output light 17 having a wavelength of 266 nm can be obtained.

The short-wavelength laser light emitted from the laser oscillator is partly scattered on the surface of the optical element or deviated from the optical axis by surface reflection and is emitted to the surrounding space. When a photocatalyst 13 given as, for example, TiO ₂ is installed at a site irradiated with such scattered light 15, the photocatalyst is excited. When the surrounding organic gas approaches the excited photocatalyst, electron exchange occurs, and the organic gas is decomposed into lower hydrocarbon-based products, CO ₂ , water, and the like.

  These products are very dilute in concentration, but are fixed to the adsorbing means 16 over a long period of time, and the organic gas is removed from the space in the housing 10. Therefore, particles such as soot generated when the organic gas is directly decomposed by the high energy beam adheres to the optical component, and this adhering matter is prevented from becoming an absorption point of the laser beam, It is possible to reduce the occurrence of damage in the case. As a result, it is possible to avoid failures such as a decrease in laser oscillation output and oscillation stop, and to reduce the maintenance frequency of the laser device. In the above embodiment, the laser oscillator is configured to generate the second harmonic and the fourth harmonic, but may be a known configuration that generates the third harmonic.

  As for the operation method of the laser device, immediately after the operation of the laser oscillator is started, it is driven at a low output to reduce harmful gases. After a predetermined time has passed and the harmful gas is decomposed and removed, the laser oscillator is driven at a high output. While the laser oscillator is driven at a low output, the photochemical action of the laser beam on the organic gas is small and the amount of particles adhering to the optical component is small. During this time, harmful gases are decomposed and removed, and then the laser oscillator is driven at a high output, thereby reducing particles adhering to optical components compared to the case where the laser oscillator is driven at a high output immediately after the start of operation. It becomes possible to do.

  As described above, according to the laser device according to the first embodiment of the present invention, the photocatalyst is installed at the site irradiated with the scattered light or the partially reflected light of the laser light emitted from the laser oscillator. Since the organic gas can be decomposed and particles adhering to the surface of the optical component can be reduced, harmful gas existing in the housing can be removed with a simple configuration, reducing the occurrence of damage to the optical component and the laser device The maintenance frequency can be reduced. Further, by installing the photocatalyst 13 at a site around the optical axis of the laser output window 14, it is possible to receive more scattered light of the laser light emitted from the laser oscillator, so that more particles adhering to the optical component can be received. This can reduce the occurrence of damage to the optical component. In addition, since the adsorption means 16 that adsorbs and removes harmful gases including organic gas is provided, it is possible to further reduce the occurrence of damage to the optical components. If the adsorption means 16 is installed on the flow path of the gas that convects due to the heat generated by the heat source such as the electric furnace 12, the adsorption ability of harmful gas is improved. Furthermore, the same effect can be obtained even if a circulation fan or the like is installed to forcibly circulate the gas in the housing 10.

Embodiment 2. FIG.
FIG. 3 is a diagram showing a configuration of a laser apparatus according to Embodiment 2 of the present invention. In FIG. 3, the same reference numerals as those in FIG. 2 indicate the same components, and the description thereof is omitted. In this embodiment, the photocatalyst 19 is installed at a site where the laser beam output from the harmonic generation element 11 is branched by a beam splitter 18 provided as a light branching unit and irradiated with the partially reflected light 20. In this case, since the power density of photoexcitation can be increased, photoexcitation occurs based on the nonlinear effect and activates the catalytic action even if the wavelength of light for exciting the photocatalyst is longer than the absorption wavelength of the photocatalyst (TiO ₂ ) 19. Is possible. Therefore, even for laser oscillators such as ultra-short pulse laser oscillators where the wavelength of the laser light is outside the ultraviolet wavelength region, optical components are prevented from being deteriorated by installing a photocatalyst in the part that is irradiated with partially reflected light in the housing. Is possible.

Embodiment 3 FIG.
FIG. 4 is a diagram showing a configuration of a laser apparatus according to Embodiment 3 of the present invention. In FIG. 4, the same reference numerals as those in FIG. In this embodiment, when the laser oscillator is not driven, the photocatalyst 23 is irradiated with ultraviolet rays 24 from a separately provided ultraviolet irradiation device 22. Examples of the ultraviolet irradiation device 22 include an LED, an LD, a mercury lamp, and the like. By irradiating the photocatalyst 23 with ultraviolet rays, it is possible to continue the decomposition reaction of harmful gases. Depending on the arrangement of the components in the housing 10, the photocatalyst may not be irradiated with the divergent light or the partially reflected light of the laser light. In such a case, the ultraviolet irradiating device 22 installed for the purpose of irradiating the photocatalyst with ultraviolet rays may be configured to always be lit. As the ultraviolet irradiation device 22, it is preferable to use an LED that outputs light having a wavelength of 365 nm to 380 nm.

  When the laser oscillator stops oscillating, the laser beam irradiation from the laser oscillator stops. By irradiating the photocatalyst 23 with ultraviolet rays from the ultraviolet irradiation device 22 provided in the housing separately from the laser oscillator, it becomes possible to remove harmful gases generated during times other than normal operation. Thereby, it is possible to realize a stable long-life operation. As for the operation method of the laser device, the ultraviolet irradiation device is driven before the laser oscillator is driven. By irradiating the photocatalyst with ultraviolet rays from an ultraviolet irradiation device, the harmful gas is decomposed and removed. After a predetermined time has passed and the harmful gas has been reduced, the laser oscillator is driven to output laser light. As a result, when the laser oscillator is driven, harmful gases are sufficiently reduced, so that particles adhering to the optical component can be reduced, and occurrence of damage to the optical component can be reduced. .

  Note that the laser device and the operation method of the laser device described in the first to third embodiments are not intended to limit the present invention, but are disclosed for the purpose of illustration. . The technical scope of the present invention is defined by the description of the scope of claims, and various design changes can be made within the technical scope of the invention described in the scope of claims. For example, in the above embodiment, the photocatalyst is provided in the laser device incorporating the Q-switched solid-state laser oscillator or the harmonic generation laser oscillator, but the CW ultraviolet ray generation laser oscillator, the ultrashort pulse laser oscillator, or the laser Of course, a configuration in which a photocatalyst is provided in another laser device incorporating an amplifier or the like is also included in the technical scope of the present invention. In particular, in an optical component provided in a laser apparatus configured with an ultrashort pulse and high output laser oscillator, a surface portion exposed to harmful gas tends to be damaged early. For this reason, it is possible to obtain a remarkable effect by applying the present invention to this kind of laser device.

  Technologies relating to stabilization and longevity of ultraviolet lasers and ultrashort pulse lasers are indispensable technologies for applying laser devices to industrial processes such as laser processing. The present invention realizes a long life of the laser oscillator and improves the reliability of the laser device. For microfabrication related to semiconductors, liquid crystals, circuit boards, and optical components (optical fibers, optical waveguides, etc.), the use of highly reliable laser devices such as short pulse lasers or ultraviolet lasers promotes their practical application. can do.

It is a figure explaining decomposition | disassembly of the organic gas by a photocatalyst. It is a figure which shows the structure of the laser apparatus by Embodiment 1 of this invention. It is a figure which shows the structure of the laser apparatus by Embodiment 2 of this invention. It is a figure which shows the structure of the laser apparatus by Embodiment 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Laser oscillation medium, 2, 3 Resonator mirror, 4 Semiconductor laser, 5 Condensing lens, 7 Q switch element, 8 Harmonic (2nd harmonic) generation element, 10 housing | casing, 11 Harmonic (4th harmonic) generation Element, 12 Heating furnace (heating source), 13, 19, 23 Photocatalyst, 14 Laser output window, 16 Adsorption means, 18 Beam splitter (branching means), 22 Ultraviolet irradiation device

Claims (12)

In a laser device configured to include a laser oscillator that emits laser light and a housing that incorporates the laser oscillator,
A laser device, wherein a photocatalyst is installed at a portion in the casing to which scattered light or partially reflected light of laser light emitted from the laser oscillator is irradiated.   2. The laser device according to claim 1, wherein a photocatalyst is installed at a site around an optical axis of a laser output window for outputting laser light from the laser device or a site in the vicinity of the laser output window. Having branching means for branching the laser light emitted from the laser oscillator;
2. The laser apparatus according to claim 1, wherein a photocatalyst is installed at a portion irradiated with the laser beam partially reflected by the branching unit.   The laser apparatus according to claim 1, further comprising an ultraviolet irradiation device that can operate independently of the laser oscillator and irradiates the photocatalyst with ultraviolet rays.   The laser apparatus according to claim 1, further comprising an adsorbing unit configured to adsorb at least a gas decomposed by the photocatalyst.   6. The laser device according to claim 5, wherein the adsorbing means or the photocatalyst is installed in the vicinity of the heat source existing in the housing.   The laser device according to claim 5 or 6, wherein the adsorption means includes an adsorbent made of zeolite.   6. The laser apparatus according to claim 1, further comprising a circulation unit that forcibly circulates the gas present in the housing.   2. The laser device according to claim 1, wherein the laser light output from the laser device is pulsed light, and the pulse width of the laser light is 1 microsecond or less.   The laser device according to claim 1, wherein the photocatalyst is titanium oxide. A laser oscillator that emits laser light; a housing that incorporates the laser oscillator; and a photocatalyst that is installed in a portion of the housing that is irradiated with scattered light or partially reflected light of the laser light emitted from the laser oscillator; An operating method for operating a laser device comprising:
Drive the laser oscillator at low power,
A method of operating a laser device, wherein a laser oscillator is driven at a high output after a predetermined time has elapsed. A laser oscillator that emits laser light; a housing that incorporates the laser oscillator; and a photocatalyst that is installed in a portion of the housing that is irradiated with scattered light or partially reflected light of the laser light emitted from the laser oscillator; An operation method of operating a laser device configured to have an ultraviolet irradiation device that can operate independently of the laser oscillator and irradiates the photocatalyst with ultraviolet rays,
Drive the ultraviolet irradiation device to irradiate the photocatalyst with ultraviolet rays,
A method for operating a laser device, comprising: driving a laser oscillator after a predetermined time has elapsed.

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