JP2003092268A - Cleaning method for light transmission window and optical output device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning method in which a deposit onto the surface of a light takeout window or a mirror at a lamp or a laser device is removed without having to conduct operation required for the removal of the deposit, i.e., without opening the device to the air, without the disassembly of the device and without polishing the surface so that the maintenance time, labor and operating costs required for the removal are reduced. SOLUTION: In the cleaning method for a light transmitting window, the deposit onto the surface of the light transmission window or a light reflecting mirror at an optical output device is removed. A radical comprising an etching property is supplied to a part on the surface 10 of the light transmitting window 8 (or the light reflecting mirror), it is made to react with a contaminant stuck to the surface 10, and the contaminant is removed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning a light transmission window for removing a contaminant attached to an inner surface of a light extraction window of a discharge lamp or a heat generation lamp, a laser light emission window of a gas laser device, and a light output. Regarding the device.

[0002]

2. Description of the Related Art The structures and operations of conventional microwave-excited hydrogen ultraviolet lamps and excimer lasers will be described with reference to typical examples. FIG. 4 is an explanatory diagram showing the configuration of a commonly used microwave-excited hydrogen ultraviolet light lamp. This configuration is based on the prior art document `` James A.
R. Samson, Techniques of VACUUM ULTRAVIOLET SPEC
TROSCOPY, Pied Publications, Lincoln, Nebraska, 19
67, p. 159, Fig. 5.56 "shows a typical microwave excited discharge lamp.

In the figure, reference numeral 1 is a discharge tube filled with discharge gas, reference numeral 2 is a discharge gas supply port for supplying discharge gas, reference numeral 3 is a gas discharge port for discharging discharge gas, and reference numeral 4 is. Microwave resonator, reference numeral 5 indicates a microwave supply connector, reference numeral 6 indicates a microwave concentrating portion, reference numeral 7 indicates discharge plasma, reference numeral 8 indicates, for example, Mg having high ultraviolet light transmission efficiency.
A light transmission window made of a material such as F ₂ or LiF, reference numeral 9 is a light emitted from the lamp, and reference numeral 10 is a surface of the light transmission window 8.

Next, an example of the light emitting operation of the microwave-excited hydrogen ultraviolet light lamp configured as described above will be described. First, 10 sccc of hydrogen discharge gas diluted to 1/100 with helium was supplied from the discharge gas supply port 2 to the discharge tube 1.
m supply. The discharge gas is exhausted from the discharge gas discharge port 3 by a vacuum pump (not shown), and the inside of the discharge tube 1 is adjusted to 1 Torr.
(Torr: 1 atm = 760 Torr (mmHg)) Microwave resonator 4 installed around the discharge tube 1
From microwave supply connector 5 to 2.45 GHz, 10
By supplying a microwave of W and adjusting a matching device (not shown), a microwave strong region is generated in the microwave concentrating portion 6 and discharge plasma 7 is generated in the discharge tube 1. The ultraviolet light from the excited hydrogen atoms generated in the discharge plasma 7, for example, the ultraviolet light having a wavelength of about 1600 to 4000 Å is passed through the light transmission window 8 for transmitting the ultraviolet light, and the lamp emission light 9
Take it out to use light like.

In such a discharge lamp, impurities in the gas adhere to the inner surface 10 of the light transmitting window 8 and the light transmittance is reduced. This determines the life of the lamp. Conventionally, in order to restore the lowered transmittance, it was necessary to replace the light transmitting window 8 or to remove the adhered matter on the surface 10 by polishing. Therefore, it was necessary to break the vacuum of the lamp. This required several hours of manual work, during which the lamp was unavailable.

The problem of lamp life due to deterioration of the light extraction window of such a lamp is not limited to the microwave-excited hydrogen ultraviolet light lamp shown here as a typical example, but the discharge gas is not hydrogen but He, Ne, Ar, Kr, Xe, O ₂ , N ₂ ,
Lamps such as D ₂ and Hg, lamps whose discharge form is not microwave-excited discharge but RF-excited discharge, arc discharge, glow discharge, dielectric barrier discharge, flash discharge, and halogen lamps that use incandescent instead of discharge This is a problem that occurs with various lamps such as carbon lamps and carbon lamps.

FIG. 5 shows a conceptual diagram of a general discharge excitation excimer laser. In the figure, reference numeral 20 is a pressure vessel in which a discharge gas is sealed in a vacuum state, reference numeral 21 is a discharge electrode to which a high voltage pulse is applied, reference numeral 22 is discharge plasma, reference numeral 23 is stimulated emission light (laser light), reference numeral 24. Is a total reflection mirror, reference numeral 25 is a semi-transmission mirror, reference numeral 30 is an inner surface of the total reflection mirror 24, and reference numeral 31 is an inner surface of the semi-transmission mirror 23.

Next, the laser oscillation operation of the discharge excitation excimer laser configured as described above will be described. First, the pressure vessel 20 is evacuated to a vacuum, and a discharge gas, which is a laser medium, such as XeCl, KrF, ArF, F.
Enclose ₂ etc. A high voltage pulse is applied to the discharge electrode 21 from a high voltage pulse power source (not shown) to discharge the discharge plasma 22.
Generate. The stimulated emission light (laser light) 23 is reflected by the total reflection mirror 24 and the semitransparent mirror 25, amplification occurs using the discharge plasma 22 as a laser medium, and a part of the semitransparent mirror 25 becomes the stimulated emission light 23. It is output to the outside.

[0009]

However, as described above, in the case of a lamp that emits light by flowing or sealing gas, a gas laser device that causes laser oscillation, etc., impurities contained in the gas are included. For example, a film or powder may be generated due to splashes generated by sputtering the material on the inner surface of the container due to discharge, hydrocarbons generated by the reverse diffusion of vacuum pump oil, powder generated by a chemical reaction during discharge, etc. There is a problem that the light adheres to the surface of an observation window or the like and reduces the light transmittance of the window.

That is, in the discharge lamp as described above, the impurities in the gas adhere to the surface 10 of the light transmitting window 8 and the light transmittance decreases. This determines the life of the lamp. Conventionally, in order to restore the lowered transmittance, it was necessary to replace the light transmitting window 8 or to remove the adhered matter on the surface 10 by polishing. Therefore, it was necessary to break the vacuum of the lamp. This required several hours of manual work, during which the lamp was unavailable.

The problem of the lamp life due to the deterioration of the light extraction window of the lamp is not limited to the microwave-excited hydrogen ultraviolet light lamp shown here as a representative example, but the discharge gas is not hydrogen but He, Ne, Ar, Kr, Xe, O ₂ , N ₂ ,
Lamps such as D ₂ and Hg, lamps whose discharge form is not microwave-excited discharge but RF-excited discharge, arc discharge, glow discharge, dielectric barrier discharge, flash discharge, and halogen lamps that use incandescent instead of discharge This is a problem that occurs with various lamps such as carbon lamps and carbon lamps.

Further, the same problem occurs in a gas laser such as an excimer laser shown in FIG. During the process of outputting the gas laser, the metal sputtered from the discharge electrode 21 by the discharge plasma 22 and the impurities present in the discharge gas adhere to the inner surfaces 30, 31 of the total reflection mirror 24 and the semi-transmission mirror 25. There is also a theory that photo-CVD by the laser light 23 occurs on the inner surfaces 30 and 31 as a cause of adhering due to this phenomenon. In any case, this total reflection mirror 2
4. There was a problem that the deposits on the inner surfaces 30 and 31 of the semi-transmissive mirror 25 deteriorate the transmittance and reflectance of these and the laser output. For this maintenance, it was necessary to open the pressure vessel 20 to the atmosphere, replace the mirrors 24 and 25, or polish the inner surfaces 30 and 31. This required several hours of manual work, during which the laser was unavailable. Such a problem occurs not only in the excimer laser but also in a CO ₂ laser or the like.

The present invention has been made in view of the above, and is a work necessary for removing the deposits on the light extraction window of a lamp or a laser device or the surface of a mirror, that is, opening the device to the atmosphere. By removing the device without disassembling it or polishing the surface, the maintenance time
The purpose is to reduce labor and work cost.

[0014]

In order to achieve the above-mentioned object, in a method for cleaning a light transmitting window according to a first aspect of the present invention, a deposit on the surface of the light transmitting window or the light reflecting mirror of the light output device. A method of cleaning a light-transmitting window for removing a substance, comprising supplying radicals having an etching property to the surface portion of the light-transmitting window or the light-reflecting mirror and reacting with a contaminant attached to the surface to remove the substance. To remove.

According to the present invention, for example, in a discharge lamp, radicals having an etching property are supplied to the inner surface of the light transmitting window to cause impurities in the discharge gas attached to the inner surface of the light transmitting window. It is possible to remove contaminants by the etching action without disassembling the device and without surface polishing.

Further, according to a second aspect of the present invention, there is provided a method of cleaning a light transmitting window, which is a method of cleaning a light transmitting window of a light output device or a light transmitting window of a light reflecting mirror to remove deposits. Radicals having an etching property are generated by electric discharge or thermal dissociation, and the radicals are supplied to the surface portion of the light transmitting window or the light reflecting mirror and reacted with the contaminants attached to the surface to remove the substance. .

According to the present invention, for example, in a discharge lamp, radicals having an etching property are generated on the surface portion of the light transmitting window by discharge or thermal dissociation, and the radicals are reacted with the contaminants adhering to the surface, By removing the substance, it becomes possible to remove the contaminants caused by the impurities in the discharge gas attached to the inner surface of the light transmission window without disassembling the device and without performing surface polishing or the like.

The cleaning method of the light transmitting window according to the third aspect is a method of cleaning the light transmitting window of the light output device or the light transmitting window of the surface of the light reflecting mirror. Gas containing halogen atoms, hydrogen atoms,
Using a pure gas containing oxygen atoms or a mixed gas containing these gases as a raw material, the radicals containing the halogen atom, the hydrogen atom, or the oxygen atom are generated and supplied to the surface portion of the light transmitting window or the light reflecting mirror. Then, the radical is reacted with the contaminant attached to the surface portion to remove the substance.

According to the present invention, for example, in a discharge lamp, a gas containing halogen atoms, a pure gas containing hydrogen atoms, oxygen atoms or a mixed gas containing these gases is supplied to the surface portion of the light transmitting window, By generating a radical containing a halogen atom, the hydrogen atom, or the oxygen atom, a contaminant caused by impurities in the discharge gas attached to the inner surface of the light transmission window is attached to the radical and the surface portion. The contaminant reacts with and is removed, so that it can be removed without disassembling the apparatus and without performing surface polishing or the like.

In addition, in the method for cleaning a light transmitting window according to a fourth aspect, a gas as a raw material of radicals having an etching property is supplied separately from a gas that causes discharge or a gas that carries heat, and In the vicinity of the transmission window or the surface part of the light reflecting mirror, both are mixed to generate radicals,
The substance is removed by reacting with contaminants adhering to the surface.

According to the present invention, for example, in a discharge lamp or the like, a gas which is a raw material of radicals having an etching property is supplied separately from a gas which causes discharge or a gas which carries heat, and the vicinity of the surface portion of the light transmission window. The two are mixed with each other to generate radicals, and by reacting with contaminants caused by impurities in the discharge gas adhering to the inner surface of the light transmitting window to remove the substances, without decomposing the device and It is possible to recover the transmission without polishing the surface.

In the method for cleaning a light transmitting window according to a fifth aspect of the present invention, the light output device is a lamp or a laser device for taking out light emission generated by discharge as light.

According to the present invention, by applying the cleaning method according to any one of claims 1 to 4 to a lamp or a laser device that takes out the light emission generated by discharge as light, a lamp light transmission window or a laser is provided. It becomes possible to remove the substances adhering to the inside of the output window without decomposing and without polishing or the like.

According to a sixth aspect of the present invention, there is provided a method of cleaning a light transmitting window, wherein when the contaminants attached to the surface portion of the light transmitting window or the light reflecting mirror are removed, etching is performed from the original light emitting gas. The raw material gas of the radical having properties is replaced.

According to the present invention, for example, when the contaminants adhering to the surface portion of the light transmitting window or the light reflecting mirror are removed from the original light emitting gas emitted from the microwave excited hydrogen ultraviolet light lamp, it has etching property. By exchanging the source gas for radicals, the removal that does not affect the original action of the gas for light emission is realized.

According to a seventh aspect of the present invention, there is provided a method for cleaning a light transmitting window, wherein an original light emitting gas of the light output device is mixed with a raw material gas of radicals having etching property in advance, or each gas is added. Supplied separately,
Radicals are generated during the light emitting operation, and the radicals are reacted with contaminants adhering to the surface to remove the substances.

According to the present invention, the original gas for light emission of the light output device is mixed with the raw material gas of the radical having the etching property in advance or supplied separately to generate the radical during the light emission operation. By reacting with the contaminants adhering to the inner surface to remove the substance, the conventional device can be used as it is.

The cleaner of the light transmitting window according to claim 8
The light transmission that is the cleaning target
MgF as the material of the window or light reflector₂, CaF₂, S
rF ₂, BaF₂, NaF, LiF, KBr, etc.
Material or SiO₂Using oxides such as
Is.

According to the present invention, in claim 1, as the material of the light transmitting window or the light reflecting mirror to be cleaned, MgF ₂ , CaF ₂ , SrF ₂ , BaF ₂ , NaF,
Halogen-based materials such as LiF and KBr, or SiO
By using an oxide such as ₂ , it is possible to perform etching without causing erosion of the light transmission window due to radicals.

In the method for cleaning the light transmitting window according to the ninth aspect, the source gas of the radical having etching property is SF ₆ , NF ₃ , F ₂ , HF, HCl,
Halogen such as Cl ₂ , CF ₄ , CCl ₄ or H ₂
It is what

According to the present invention, in claim 3, the source gas of the radical having etching property is SF ₆ , N.
By using a halide such as F ₃ , F ₂ , HF, HCl, Cl ₂ , CF ₄ , CCl ₄ or H ₂ , discharge or thermal dissociation can be effectively generated.

According to a tenth aspect of the present invention, there is provided a method of cleaning a light transmission window, wherein the output light amount of the light output device is detected, and when the output light amount is equal to or less than a preset light amount,
The contaminants adhering to the surface portion of the light transmitting window or the light reflecting mirror are removed.

According to the present invention, for example, the light amount of the output light that has passed through the light transmission window is monitored, and when the light amount reaches a certain level or less, contaminants are attached to the window portion and the light amount is increased. It is possible to automatically remove the adhering substance, assuming that the temperature has gone down.

According to the eleventh aspect of the present invention, there is provided a method of cleaning a light transmission window, wherein the light transmission is performed when a preset fixed time, a fixed irradiation time, or a fixed irradiation energy is reached. It removes contaminants adhering to the surface of the window or the light reflecting mirror.

According to the present invention, a constant time, a constant irradiation time, or a constant irradiation energy value is set in advance, and when this value is reached, contaminants adhere to the window portion. However, it is possible to automatically remove the adhering material, assuming that the light amount has decreased.

Further, in the light output device according to the twelfth aspect, in the light output device for outputting light through the light transmitting window or the light reflecting mirror, radicals having etching property are added to the light transmitting window or the light transmitting window. It is provided with a removing means for supplying the light to the surface portion of the reflecting mirror and reacting with the contaminant attached to the surface to remove the substance.

According to the present invention, in a light output device such as a discharge lamp, radicals having an etching property are supplied to the inner surface of the light transmitting window so that the inside of the discharge gas adhered to the inner surface of the light transmitting window. It becomes possible to remove the contaminants caused by the impurities of (1) above without disassembling the device by etching action and without performing surface polishing or the like.

Further, in the light output device according to the thirteenth aspect, in the light output device for outputting light through the light transmitting window or the light reflecting mirror, the surface portion of the light transmitting window or the light reflecting mirror is provided. A means for generating radicals having an etching property by electric discharge or thermal dissociation and reacting with a contaminant attached to the surface to remove the substance is provided.

According to the present invention, in a light output device such as a discharge lamp, radicals having an etching property are generated by discharge or thermal dissociation on the surface portion of the light transmission window, and contaminants attached to the surface are generated. By removing the substance by reacting with, the contaminants caused by impurities in the discharge gas adhering to the inner surface of the light transmitting window can be removed without disassembling the device and without performing surface polishing or the like. Will be possible.

Further, in the light output device according to the fourteenth aspect, in the light output device for outputting light through the light transmitting window or the light reflecting mirror, the surface portion of the light transmitting window or the light reflecting mirror is , A gas containing a halogen atom, a hydrogen atom, a pure gas containing an oxygen atom or a mixed gas containing these gases is supplied to generate a radical containing the halogen atom, the hydrogen atom, or the oxygen atom, and the radical. It is provided with a removing means for removing the substance by reacting with the contaminant attached to the surface portion.

According to the present invention, in a light output device such as a discharge lamp, a gas containing a halogen atom, a pure gas containing a hydrogen atom, an oxygen atom or a mixed gas containing these gases is provided on the surface portion of the light transmitting window. To generate a radical containing the halogen atom, the hydrogen atom, or the oxygen atom, the pollutant caused by the impurities in the discharge gas attached to the inner surface of the light transmission window is The contaminants adhering to the surface portion are removed by reaction, and it is possible to remove the contaminants without disassembling the device and without polishing the surface.

Further, in the light output device according to the fifteenth aspect, the removing means supplies the gas as a raw material of radicals having an etching property separately from the gas causing the discharge or the gas carrying heat. In the vicinity of the surface portion of the light transmitting window or the light reflecting mirror, the two are mixed to generate radicals, which react with contaminants adhering to the surface to remove the substance.

According to the present invention, for example, in a light output device such as a discharge lamp, a gas as a raw material of radicals having an etching property is supplied separately from a gas that causes discharge or a gas that carries heat, and the gas of the light transmission window is supplied. By mixing the two in the vicinity of the surface part to generate radicals and reacting with contaminants caused by impurities in the discharge gas adhering to the inner surface of the light transmitting window to remove the substances, the device is decomposed. It is possible to recover the transmittance without and without polishing the surface.

Further, in the light output device according to the sixteenth aspect, when the removing means removes the contaminants adhering to the surface portion of the light transmitting window or the light reflecting mirror, the original light emitting gas is used. Therefore, the source gas for the radical having etching property is replaced.

According to the present invention, when the contaminants adhering to the surface portion of the light transmitting window or the light reflecting mirror are removed from the original light emitting gas emitted from the light output device such as a microwave excited hydrogen ultraviolet lamp. By replacing the source gas of the radical having the etching property, the removal that does not affect the original action of the gas for light emission is realized.

Further, in the light output device according to the seventeenth aspect, the removing means adds the raw material gas of the radical having etching property to the original light emitting gas of the light output device in advance. Alternatively, they are separately supplied to generate radicals during the light emitting operation and react with the contaminants adhering to the surface to remove the substances.

According to the present invention, the original gas for light emission of the light output device is mixed with the raw material gas of the radical having the etching property in advance or supplied separately to generate the radical during the light emission operation. By reacting with the contaminants adhering to the inner surface to remove the substance, the conventional device configuration can be used as it is.

Further, in the light output device according to the eighteenth aspect, MgF ₂ , CaF ₂ , SrF ₂ and Ba are used as the material of the light transmitting window or the light reflecting mirror to be cleaned.
A halogen-based material such as F ₂ , NaF, LiF or KBr, or an oxide such as SiO ₂ is used.

According to the present invention, in the light output device according to the twelfth aspect, as the material of the light transmitting window or the light reflecting mirror to be cleaned, MgF ₂ , CaF ₂ , SrF ₂ ,
By using a halogen-based material such as BaF ₂ , NaF, LiF, or KBr, or an oxide such as SiO ₂ , etching can be performed within a range that does not corrode the light transmission window.

Further, in the light output device according to the nineteenth aspect, the source gas for the radical having etching property is SF ₆ , NF ₃ , F ₂ , HF, HCl, Cl ₂ , C.
A halide such as F ₄ , CCl ₄ or H ₂ is used.

According to the present invention, in the light output device according to the fourteenth aspect, the source gas for the radical having etching property is SF ₆ , NF ₃ , F ₂ , HF, HCl, Cl ₂ , C.
By using a halide such as F ₄ or CCl ₄ or H ₂ , it becomes possible to effectively generate discharge or thermal dissociation.

Further, in the light output device according to the twentieth aspect, further, a light amount detecting means for detecting the light amount from the light transmitting window or the light reflecting mirror is provided, and the light amount detected by the light amount detecting means is When the amount of light is less than a preset amount, contaminants attached to the surface portion of the light transmitting window or the light reflecting mirror are removed.

According to the present invention, for example, the light amount of the output light which has passed through the light transmitting window is monitored by the light amount detecting means such as a photodiode, and when the light amount reaches a certain level or less, the window portion It is considered that the pollutant has adhered to and the amount of light has decreased, and the adhered matter can be automatically removed.

According to a twenty-first aspect of the present invention, in the light output device, the removing means is configured such that, when a preset time, a predetermined irradiation time, or a constant irradiation energy is reached, The purpose is to remove contaminants adhering to the surface portion of the light transmitting window or the light reflecting mirror.

According to the present invention, a constant time, a constant irradiation time, or a constant irradiation energy value is set in advance, and when this value is reached, contaminants adhere to the window portion. However, it is possible to automatically remove the adhering material, assuming that the light amount has decreased.

Further, in the light output device according to the twentieth aspect, the removing means is incorporated in a lamp or a laser device for taking out light emission generated by discharge as light.

According to the present invention, by applying the above cleaning method to a light output device such as a lamp or a laser device that takes out the light emission generated by discharge as light, the lamp light transmission window or the laser output window is provided inside. It becomes possible to remove the adhering substance without decomposing and without polishing or the like.

[0058]

BEST MODE FOR CARRYING OUT THE INVENTION Preferred embodiments of a method for cleaning a light transmitting window and a light output device according to the present invention will be described in detail below with reference to the accompanying drawings. The present invention is not limited to this embodiment.

In order to solve the above-mentioned problems, the present inventors have conducted a component analysis of the deposit. It has been conventionally said that carbon is a large amount of deposits on the surface of the light transmitting window, but as a result of investigation using the lamp device shown in FIG. 4, it was found that the film was a Si film containing some oxygen atoms. By the way, it is considered that the cause of the adhesion of Si is quartz (SiO ₂ ) used in the discharge tube. From the above, it was found that it is particularly necessary to remove Si or carbon adhering to the surface of the window or the mirror in order to maintain the transmittance of the window or the reflectance of the mirror in a good state. Hereinafter, a specific embodiment for removing foreign matter on the inner surface of the light transmitting window or the light reflecting mirror will be described.

(Embodiment 1) FIG. 1 is an explanatory view showing the structure of a microwave-excited hydrogen ultraviolet light lamp according to Embodiment 1 of the present invention, in which a light transmission window 8 in the microwave-excited hydrogen ultraviolet light lamp is shown. 2 shows a configuration in which a cleaning function by etching the inner surface 10 of FIG. This configuration is almost the same as the conventional example shown in FIG. 4, but an etching gas supply port 11 for supplying an etching gas is provided near the window. Further, in order to monitor the output light quantity, a photodiode 12 for receiving the light emitted by the ultraviolet lamp is installed.

Next, an evaluation experiment of the microwave-excited hydrogen ultraviolet light lamp configured as described above was conducted. First, this lamp was used for 10 days by the usual usage method as shown in the conventional example. Photodiode 12 for measuring light quantity
It was found that the amount of light emitted from the lamp 9 emitted from the lamp was halved. This is because the transmittance of the MgF ₂ light-transmitting window 8 is reduced to half that of a new product. The cause is that the discharge tube 1 is sputtered by the discharge plasma 7, and Si scattered from the discharge plasma 1 adheres to the inner surface 10 of the light transmission window 8 as a Si film.

The etching operation was performed as follows. He gas as a gas for generating a discharge was supplied to the discharge tube 1 at a flow rate of 5 sccm, and the pressure inside the discharge tube 1 was set to 5 Torr by a vacuum pump (not shown). Oscillation frequency 2.45GH
By supplying a microwave having an output power of 10 W from the microwave supply connector 5 and adjusting a matching device (not shown), a region having a high microwave intensity is generated in the microwave concentrating portion 6 and the microwave is generated in the discharge tube 1. A discharge plasma 7 was generated.

The discharge plasma 7 is He plasma (Plas
ma) and flows toward the gas outlet 3. on the other hand,
NF ₃ gas as an etching raw material, the flow rate is 0.5 sccm
It was supplied from the etching gas supply port 11. Then H
The raw materials of the e plasma and the etching gas are mixed in the vicinity of the inner surface 10 of the light transmission window 8, and NF ₃ is dissociated to generate F atom radicals (excited species, active species, free radicals). The F atom radicals react with Si, which is a deposit on the inner surface 10, to become SiF ₄ , which is vaporized in the gas and flows toward the gas outlet 3. The etching is performed in this manner.

The following verification results were obtained regarding the effect of removing deposits by this etching. Ie 1
A light-transmissive window whose transmittance was reduced to 1/2 of that of a new product after use for 0 days was treated for 10 minutes by this method. As a result, the transmittance of the light-transmissive window 8 was recovered to 90% of that of the new product. Since the light transmission window 8 itself is made of fluoride (MgF ₂ ), it was not etched by F atom radicals. As described above, if the surface to be cleaned is made of a material that is not easily attacked by halogen, oxygen, or the like used for etching, it is convenient because it is less likely to be etched.

Similarly, when repeated normal use and etching were performed, it was verified that the transmittance after etching was always recovered to about 90% of that of a new product. In addition,
It is considered that the reason why 100% of the new product is not recovered is that Si atoms sputtered by the discharge plasma 7 from the discharge tube 1 adhere to the inner surface 10 of the window even during etching.

The photodiode 12 is used to measure the amount of ultraviolet light. That is, the use of the photodiode 12 for measuring the irradiation intensity of the lamp and the maintenance time are automatically recognized by this etching method.
At the same time, maintenance can be performed automatically, which reduces the time and effort required for disassembly and assembly, contributing to cost reduction.

(Second Embodiment) In the second embodiment,
The structure of the conventional microwave-excited hydrogen ultraviolet light lamp shown in FIG. 4 is used as it is. An evaluation experiment of the microwave-excited hydrogen ultraviolet light lamp configured as described above was conducted. First, when this lamp was used for 10 days by the usual usage method as shown in the conventional example, the transmittance of the window was reduced to half that of the new product.

Etching was performed as follows. The operation as a lamp was stopped, and the discharge gas supplied to the discharge tube 1 was changed from the H ₂ / He mixed gas for the hydrogen lamp to the mixed gas of He and SF ₆ . This mixed gas is He:
It is mixed in a cylinder (not shown) at a ratio of SF ₆ = 20: 1. This cylinder was supplied through the discharge gas supply port 2 at a flow rate of 10 sccm. Microwave supply connector 5
A microwave was supplied from the above, and matching was performed by a matching device (not shown) to generate discharge plasma 7 in the discharge tube 1. This microwave was supplied from the same microwave oscillator (not shown) used for the lamp with the same oscillation frequency of 2.45 GHz as that used for the lamp at an output of 7 W.

The following verification results were obtained regarding the effect of removing deposits by this etching. Ie 1
As a result of treating the light-transmitting window 8 whose transmittance has been reduced to 1/2 of that of a new product after 0 day of use for 30 minutes by this method, the transmittance of the window 8 has recovered to 90% of that of the new product. Since the light transmission window 8 is made of fluoride (LiF), it was not etched by F atom radicals.

When ordinary use and etching were repeated in the same manner, the transmittance of the light transmission window 8 after the etching treatment was always recovered to nearly 90% of that of the new product. The reason why 100% of the new product is not recovered is considered to be that Si atoms sputtered by the discharge plasma 7 from the discharge tube 1 adhere to the inner surface 10 of the window even during etching.

This method is characterized in that etching can be performed by using the lamp device as it is. However, when the microwave power supplied to shorten the processing time is increased, the discharge tube is etched and finally the discharge tube is etched. There is a problem that the pinhole opens. Therefore, it is necessary to reduce the microwave power and increase the processing time. On the other hand, the first embodiment described above
Has the problems that it is necessary to provide a gas supply system for the etching gas separately from the gas supply system for the lamp and that it is preferable to use NF ₃ which is easy to dissociate but is expensive, but the processing time is short. Is a feature. It was verified that the same effect can be obtained by using H ₂ gas as a raw material gas for etching.

The lamp is used for ultraviolet spectroscopic measurement. The maintenance work, which was required in the past, can now be performed automatically every other week, which reduces the time and work required for disassembly and assembly, contributing to cost reduction.

(Third Embodiment) FIG. 2 is an explanatory view showing the structure of a microwave-excited hydrogen ultraviolet light lamp according to a third embodiment of the present invention, showing a structure added with a cleaning function by etching. ing. This structure is almost the same as the conventional example shown in FIG. 4, except that an etching gas supply port 11 for supplying an etching gas is provided near the window, and a tungsten filament 13 for thermally dissociating the etching gas is provided, and a direct current is provided. The power supply 14 can be energized and heated.

Next, an evaluation experiment of the microwave-excited hydrogen ultraviolet light lamp configured as described above was conducted. First, when this lamp was used for 10 days by the usual usage method as shown in the conventional example, the transmittance of the light transmission window 8 was reduced to half of that of a new product.

The etching was performed as follows. The operation as a lamp was stopped, and the discharge gas supplied to the discharge tube 1 was stopped. Hydrogen gas was supplied from a cylinder (not shown) through the etching gas supply port 11 at a flow rate of 2 sccm. A DC current of 1 A is supplied from the DC power supply 14 to the tungsten filament 13,
The hydrogen gas was thermally dissociated by the catalytic reaction with to generate hydrogen atom radicals.

The following verification results were obtained regarding the effect of removing deposits by this etching. Ie 1
A window whose transmittance has dropped to 1/2 of that of a new product when used for 0 days,
As a result of processing for 5 minutes by this method, the transmittance of the light transmitting window 8 was restored to 90% of that of the new product.

When ordinary use and etching were repeated in the same manner, after the etching treatment, it was always recovered to nearly 60% of that of the new product. The reason why the new product is not recovered to 100% is that the direct current is reduced, the generation amount of hydrogen atom radicals is suppressed, the etching is performed gently, and the etching time is shortened.

When the DC current supplied to shorten the processing time is increased or the processing time is lengthened, the light transmission window 8
However, this method has a problem that the inner surface 10 of the light transmission window 8 is roughened and the transmittance is lowered, because of the etching of the MgF ₂ used for the above. This method uses a halogen-based gas as an etching gas. Since it is not used, it is characterized in that absorption by impurities such as halogen, which is a problem during lamp operation, can be prevented.

(Embodiment 4) FIG. 3 is an explanatory diagram showing the structure of an excimer laser according to a fourth embodiment of the present invention, in which the total reflection mirror 24 and the semi-transmission mirror 25 of the excimer laser are cleaned by etching. It is the device that has performed. The structure is the same as the conventional example shown in FIG. 4 except that a plasma source (comprising a discharge tube 26 and an induction coil 27) for supplying radicals for etching is provided near the total reflection mirror 24 and the semitransparent mirror 25. . The coating material of the inner surface 30 of the total reflection mirror 24 is made of MgF ₂ , and the inner surface 31 of the semi-transparent mirror 25 has no coating and is made of SiO ₂ .

Next, an evaluation experiment of the excimer laser configured as described above was conducted. First, when this device was used by laser oscillation for 10 days by a normal use method, the reflectances of the total reflection mirror 24 and the semi-transmission mirror 25 fell to 95% of those of the new product. Total reflection mirror 24 and semi-transmission mirror 2 after use
When the inner surfaces 30 and 31 of No. 5 were examined, it was found that carbon was attached.

The etching was performed as follows. The operation as a laser was stopped, and O ₂ gas was supplied as a discharge gas to the discharge tube 26 for generating radicals. O ₂ gas was supplied to the discharge tube 26 from a cylinder (not shown) at a flow rate of 20 sccm. A high frequency power of 13.5 MHz is supplied from the high frequency power supply 28 to the induction coil 27 to discharge O ₂ gas,
O atom radicals or ozone radicals were generated. The generated radicals are in the form of a jet, as shown by reference numeral 29.
4, the inner surfaces 30, 31 of the semi-transparent mirror 25 are illuminated,
The carbon deposits on the inner surfaces 30, 31 are cleaned by etching.

The following verification results were obtained regarding the effect of removing deposits by this etching. Ie 1
A window whose transmittance has dropped to 95% of that of a new product after 0 days of use,
As a result of performing the treatment for 20 minutes by this method, the reflectances of the total reflection mirror 24 and the semi-transmission mirror 25 were restored to 99% of the original values. The inner surface 30 of the total reflection mirror 24 is coated with Mg.
It was made of F ₂ , and the inner surface 31 of the semitransparent mirror 25 had no coating and was made of SiO ₂ , and no damage due to O atom radicals or ozone radicals was observed.

Similarly, when the ordinary use and the etching were repeatedly performed, it was found that after the etching treatment, the 9
It recovered to nearly 9%.

Therefore, according to each of the embodiments described above, the surface of the light-transmitting window or the mirror due to the sputtering due to the discharge or the impurities in the gas, which causes the decrease in the transmittance of the window and the reflectance of the mirror. It is possible to remove the deposits on the surface without polishing, exchanging or disassembling, and it is possible to reduce the labor and time required for maintenance work.

[0085]

As described above, according to the method for cleaning a light transmitting window according to the present invention (claim 1), for example, in a discharge lamp, radicals having an etching property are supplied to the inner surface of the light transmitting window. By doing so, it becomes possible to remove contaminants caused by impurities in the discharge gas adhering to the inner surface of the light-transmitting window without disassembling the device by etching and without polishing the surface. This shortens and simplifies maintenance work for removing deposits on the take-out window and the surface of the mirror, and reduces work cost.

Further, according to the method for cleaning a light transmitting window according to the present invention (claim 2), radicals having an etching property are generated by discharge or thermal dissociation in, for example, a discharge lamp, and the surface portion of the light transmitting window is generated. By supplying and reacting with the pollutants adhering to the surface to remove the pollutants, the pollutants due to impurities in the discharge gas adhering to the inner surface of the light transmission window do not decompose the device. In addition, it can be removed without performing surface polishing, etc., so the maintenance work for removing the deposits on the surface of the light extraction window and the mirror can be shortened, simplified, and the work cost reduced. Will be realized.

According to the method for cleaning a light transmitting window according to the present invention (claim 3), for example, in a discharge lamp, a gas containing a halogen atom, a pure gas containing a hydrogen atom, an oxygen atom, or a gas thereof is contained. By using a mixed gas as a raw material and generating radicals containing the halogen atom, the hydrogen atom, or the oxygen atom and supplying the radicals to the surface portion of the light transmitting window, the discharge gas in the discharge gas adhered to the inner surface of the light transmitting window Contaminants resulting from impurities are removed by the reaction between the radicals and the contaminants attached to the surface portion, and can be removed without disassembling the apparatus and without performing surface polishing or the like. This makes it possible to shorten and simplify the maintenance work for removing the deposits on the surface of the light extraction window and the mirror, and to reduce the work cost.

Further, according to the method for cleaning a light transmitting window according to the present invention (claim 4), for example, in a discharge lamp or the like, a gas which is a raw material of radicals having an etching property is carried by a gas or heat which causes a discharge. It is supplied separately from the gas, and the two are mixed in the vicinity of the surface portion of the light transmitting window to generate radicals, which react with pollutants caused by impurities in the discharge gas adhering to the inner surface of the light transmitting window to generate radicals. By removing the material, it is possible to restore the transmission without disassembling the device and polishing the surface, thus removing deposits on the surface of the light extraction window or mirror. It is possible to reduce maintenance time, labor and work cost.

According to the method for cleaning a light transmitting window according to the present invention (claim 5), the lamp or the laser device for taking out the light emission generated by the discharge as light is described in any one of claims 1 to 4. By applying the cleaning method to, it is possible to remove the substances adhering to the inside of the window for transmitting the lamp light or the laser output window without disassembling and without polishing, etc. The output of the lamp or laser device can be maintained in a stable state at low cost.

Further, according to the method for cleaning a light transmitting window according to the present invention (claim 6), for example, from the original light emitting gas emitted by the microwave excited hydrogen ultraviolet light lamp,
When removing the contaminants adhering to the surface of the light transmitting window or the light reflecting mirror, by replacing the source gas of the radical having etching property, the removal that does not affect the original action of the light emitting gas is realized and The deposit can be removed by using the apparatus configuration described above.

Further, according to the method for cleaning a light transmitting window according to the present invention (claim 7), a raw material gas for radicals having an etching property is previously mixed and added to the original light emitting gas of the light output device, Alternatively, they are separately supplied, radicals are generated during the light emission operation, and the substances are removed by reacting with the contaminants adhering to the inner surface, so that they can be used as they are without changing the conventional device configuration. be able to.

According to the cleaning method of the light transmitting window (claim 8) of the present invention,
As the material of the light transmission window or the light reflection mirror to be cleaned, MgF ₂ , CaF ₂ , SrF ₂ , BaF ₂ , Na
Halogen-based materials such as F, LiF, KBr, or S
Since an oxide such as iO ₂ is used, etching for effective removal of deposits without erosion of the light transmission window is realized.

According to the cleaning method of the light transmitting window (claim 9) of the present invention,
The source gas of the radical having etching property is SF ₆ , N
Since halide such as F ₃ , F ₂ , HF, HCl, Cl ₂ , CF ₄ , CCl ₄ or H ₂ is used, discharge or thermal dissociation can be effectively generated.

Further, according to the cleaning method of the light transmitting window according to the present invention (claim 10), for example, the light amount of the output light which has passed through the light transmitting window is monitored, and the light amount reaches a certain level or less. In this case, contaminants adhere to the window and it is considered that the amount of light has decreased, and it is possible to automatically remove the adhered matter, so the transmittance of the output window can always be kept constant. Therefore, the cleaning work is unnecessary and a stable light output can be obtained.

Further, according to the method for cleaning a light transmitting window according to the present invention (claim 11), a fixed time, a fixed irradiation time, or a fixed irradiation energy value is set in advance, and When the value is reached, it is considered that the contaminant has adhered to the window and the light intensity has decreased, and it is possible to automatically remove the adhered matter, so the transmittance of the output window is always kept constant. Therefore, the cleaning work is not necessary and stable light output can be achieved.

According to the light output device of the present invention (claim 12), by supplying radicals having an etching property to the inner surface of the light transmission window in a light output device such as a discharge lamp, Contaminants resulting from impurities in the discharge gas attached to the inner surface of the light transmitting window can be removed without disassembling the device by etching and without performing surface polishing.
This makes it possible to shorten and simplify the maintenance work for removing the deposits on the surface of the light extraction window and the mirror, and to reduce the work cost.

According to the light output device of the present invention (claim 13), in a light output device such as a discharge lamp, radicals having an etching property are generated by discharge or thermal dissociation, and the surface of the light transmitting window is generated. By supplying it to the part and reacting with the contaminants adhering to the surface to remove the substance, the contaminants caused by the impurities in the discharge gas adhering to the inner surface of the light transmitting window are decomposed in the device. Since it can be removed without polishing and without polishing the surface, the maintenance work for removing the deposits on the surface of the light extraction window and the mirror can be shortened, simplified, and work cost can be reduced. Reduction is realized.

According to the light output device of the present invention (Claim 14), for example, in a light output device such as a discharge lamp, a gas containing a halogen atom, a pure gas containing a hydrogen atom, an oxygen atom or a gas thereof. A discharge gas attached to the inner surface of the light transmitting window by generating a radical containing a halogen atom, the hydrogen atom, or the oxygen atom from a mixed gas containing Contaminants caused by impurities inside are removed by reacting with the radicals and can be removed without disassembling the device and without polishing the surface. It is possible to shorten and simplify the maintenance work for removing the deposits on the surface and reduce the work cost.

Further, according to the light output device of the present invention (claim 15), in a light output device such as a discharge lamp, a gas as a raw material of radicals having an etching property is converted into a gas or heat which causes a discharge. It is supplied separately from the gas to be carried, and the two are mixed in the vicinity of the surface part of the light transmission window to generate radicals, which react with contaminants caused by impurities in the discharge gas adhering to the inner surface of the light transmission window. By removing the substance, it becomes possible to recover the transmittance without disassembling the device and polishing the surface of the device, so that the deposits on the surface of the light extraction window and the mirror are removed. Therefore, it is possible to reduce maintenance time, labor and work cost.

Further, according to the light output device of the present invention (claim 16), a light transmitting window or a light reflecting mirror is emitted from an original emission gas emitted from a light output device such as a microwave excited hydrogen ultraviolet light lamp. When removing the contaminants adhering to the surface part of the device, the source gas of the radical having etching property is replaced, so that the removal that does not affect the original action of the gas for light emission is realized and the conventional device configuration is used. The kimono can be removed.

According to the light output device of the present invention (claim 17), the original gas for light emission of the light output device is
Source gas of radicals having etching property is mixed in advance and supplied separately, and radicals are generated during light emission operation, and react with pollutants adhering to the inner surface to remove the substance. This makes it possible to use the conventional device configuration as it is,
It is possible to remove the deposit using the conventional device configuration.

According to the optical output device of the present invention (claim 18), in the optical output device of claim 12,
As the material of the light transmission window or the light reflection mirror to be cleaned, MgF ₂ , CaF ₂ , SrF ₂ , BaF ₂ , Na
Halogen-based materials such as F, LiF, KBr, or S
By using an oxide such as iO ₂ , it is possible to perform etching within a range that does not corrode the light transmitting window, etc. Therefore, etching for effectively removing deposits is realized without corroding the light transmitting window.

According to the optical output device of the present invention (claim 19), in the optical output device of claim 14,
The source gas of the radical having etching property is SF ₆ , N
By using a halide such as F ₃ , F ₂ , HF, HCl, Cl ₂ , CF ₄ , CCl ₄ or H ₂ , discharge or thermal dissociation can be effectively generated. Thermal dissociation can be effectively generated.

According to the light output device of the present invention (claim 20), for example, the light amount of the output light which has passed through the light transmitting window is monitored by the light amount detecting means such as a photodiode, and the light amount is When the temperature reaches a certain level or less, it is considered that the contaminant has adhered to the window and the amount of light has decreased, and it is possible to automatically remove the adhered matter, so the transmittance of the output window is always constant. Can be kept in
The cleaning work becomes unnecessary and a stable light output can be obtained.

Further, according to the light output device of the present invention (claim 21), a predetermined time, a constant irradiation time, or a constant irradiation energy value is set in advance, and this value is reached. In this case, contaminants adhere to the window and it is considered that the amount of light has decreased, and it is possible to automatically remove the adhered matter, so the transmittance of the output window can always be kept constant. Therefore, the cleaning work is unnecessary and a stable light output can be obtained.

Further, according to the light output device of the present invention (claim 22), the above cleaning method is applied to a light output device such as a lamp or a laser device for taking out light emission generated by discharge as light. By removing substances adhering to the inside of the lamp light transmission window or the laser output window without disassembling and without polishing, the equipment is not disassembled and surface polishing is not performed. It is possible to reduce the maintenance time, labor and work cost while avoiding the opening.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a microwave-excited hydrogen ultraviolet light lamp according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing the structure of a microwave-excited hydrogen ultraviolet light lamp according to a third embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a structure of an excimer laser according to a fourth embodiment of the present invention.

FIG. 4 is an explanatory diagram showing the configuration of a commonly used microwave-excited hydrogen ultraviolet light lamp.

FIG. 5 is an explanatory diagram showing a configuration of a general discharge excitation excimer laser.

[Explanation of symbols]

1 discharge tube 2 supply port 3 gas outlet 4 microwave resonator 5 Microwave supply connector 6 Microwave concentrator 7 discharge plasma 8 light transmission window 9 Lamp output light 10 Inner surface 11 Etching gas supply port 20 Pressure vessel 21 discharge electrode 24 total reflection mirror 25 semi-transparent mirror 26 Discharge tube 27 induction coil 30,31 inner surface

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Satoshi Sakai             1-8-1 Sachiura, Kanazawa-ku, Yokohama             Industrial Technology Research Institute (72) Inventor Minoru Danno             1-8-1 Sachiura, Kanazawa-ku, Yokohama             Yokohama Co., Ltd.

Claims (22)

[Claims] 1. A method for cleaning a light transmitting window of a light output device or a surface of a light reflecting mirror for removing deposits, wherein radicals having an etching property are added to the surface of the light transmitting window or the light reflecting mirror. A method for cleaning a light-transmitting window, which comprises: supplying a part to a portion and reacting with a contaminant attached to the surface to remove the substance. 2. A method for cleaning a light transmitting window of a light output device or a light transmitting window for removing deposits on the surface of a light reflecting mirror, wherein radicals having an etching property are generated by discharge or thermal dissociation, A method for cleaning a light-transmitting window, which comprises supplying the light-transmitting window or a surface portion of a light reflecting mirror to react with a contaminant attached to the surface to remove the substance. 3. A method of cleaning a light transmitting window of a light output device or a light transmitting window for removing deposits on the surface of a light reflecting mirror, which comprises a gas containing a halogen atom, a pure gas containing a hydrogen atom and an oxygen atom. Using a mixed gas containing these gases as a raw material, a radical containing the halogen atom, the hydrogen atom, or the oxygen atom is generated and supplied to the surface portion of the light transmission window or the light reflection mirror, and the radical and the surface. A method for cleaning a light transmitting window, which comprises reacting a contaminant attached to a portion to remove the substance. 4. A gas, which is a raw material of radicals having an etching property, is supplied separately from a gas that causes discharge or a gas that carries heat, and the two are mixed in the vicinity of the surface portion of the light transmitting window or the light reflecting mirror. The method of cleaning a light-transmitting window according to claim 2, wherein radicals are generated by the reaction to react with a contaminant attached to the surface to remove the substance. 5. The method for cleaning a light transmitting window according to claim 1, wherein the light output device is a lamp or a laser device that takes out the light emission generated by discharge as light. . 6. The raw material gas of the radical having etching property is replaced from the original light emitting gas when removing the contaminants attached to the surface portion of the light transmitting window or the light reflecting mirror. 5. The method for cleaning a light transmitting window according to item 5. 7. The original gas for light emission of the light output device,
A source gas of radicals having an etching property is previously mixed and added, or they are separately supplied to generate radicals during the light emitting operation, and react with pollutants attached to the surface to remove the substance. The method for cleaning a light transmitting window according to claim 2, wherein 8. The material of the light transmitting window or the light reflecting mirror to be cleaned is MgF ₂ , CaF ₂ , SrF ₂ ,
The method for cleaning a light transmitting window according to claim 1, wherein a halogen-based material such as BaF ₂ , NaF, LiF or KBr or an oxide such as SiO ₂ is used. 9. The raw material gas of the radical having etching property is SF ₆ , NF ₃ , F ₂ , HF, HCl, Cl ₂ , C
The method for cleaning a light transmitting window according to claim 3, wherein the cleaning agent is a halide such as F ₄ or CCl ₄ , or H ₂ . 10. The output light amount of the light output device is detected,
The method for cleaning a light-transmitting window according to claim 1, wherein contaminants attached to the surface of the light-transmitting window or the light-reflecting mirror are removed when the amount of light is not more than a preset amount. 11. The preset fixed time,
2. The light transmitting window according to claim 1, wherein contaminants attached to the surface portion of the light transmitting window or the light reflecting mirror are removed when a certain irradiation time or a certain irradiation energy is reached. Cleaning method. 12. A light output device for outputting light through a light transmitting window or a light reflecting mirror, wherein radicals having an etching property are supplied to a surface portion of the light transmitting window or the light reflecting mirror and adhered to the surface. A light output device, comprising: a removing unit that reacts with a pollutant present to remove the substance. 13. A light output device for outputting light through a light transmitting window or a light reflecting mirror, wherein radicals having an etching property are generated on the surface portion of the light transmitting window or the light reflecting mirror by discharge or thermal dissociation. A light output device comprising: a removing unit that reacts with a contaminant attached to the surface to remove the substance. 14. A light output device for outputting light through a light transmitting window or a light reflecting mirror, wherein the surface portion of the light transmitting window or the light reflecting mirror contains a gas containing a halogen atom, a hydrogen atom, and an oxygen atom. By supplying a pure gas or a mixed gas containing these gases, a radical containing the halogen atom, the hydrogen atom, or the oxygen atom is generated, and the radical is reacted with a contaminant attached to the surface portion to generate a radical. A light output device comprising a removing means for removing a substance. 15. The removing means supplies a gas, which is a raw material of radicals having an etching property, separately from a gas that causes discharge or a gas that carries heat, and near the light transmitting window or the surface portion of the light reflecting mirror. 13. The light output device according to claim 12, wherein the two are mixed with each other to generate a radical, and the radical is caused to react with the contaminant to remove the substance. 16. The removing means removes contaminants adhering to the surface portion of the light transmitting window or the light reflecting mirror,
13. The light output device according to claim 12, wherein a raw material gas of radicals having an etching property is replaced with the original gas for light emission. 17. The removing means premixes an original light emitting gas of the light output device with a raw material gas of radicals having an etching property, or supplies them separately to supply radicals during the light emitting operation. 13. The light output device according to claim 12, wherein the light output device is produced and reacted with a contaminant attached to the surface to remove the substance. 18. The material of the light transmitting window or the light reflecting mirror to be cleaned is MgF ₂ , CaF ₂ , Sr.
13. The light output device according to claim 12, wherein a halogen-based material such as F ₂ , BaF ₂ , NaF, LiF, or KBr, or an oxide such as SiO ₂ is used. 19. The raw material gas of the radical having etching property is SF ₆ , NF ₃ , F ₂ , HF, HCl, Cl ₂ ,
The light output device according to claim 14, which is a halide such as CF ₄ or CCl ₄ , or H ₂ . 20. The light output device according to claim 12, wherein the removing unit is incorporated in a lamp or a laser device that extracts light emitted by discharge as light. 21. Further, a light amount detecting means for detecting the light amount from the light transmitting window or the light reflecting mirror is provided, and when the light amount detected by the light amount detecting means is equal to or less than a preset light amount, 13. The light output device according to claim 12, wherein contaminants attached to the surface portion of the light transmitting window or the light reflecting mirror are removed. 22. The removing means adheres to a surface portion of the light transmitting window or the light reflecting mirror when a preset predetermined time, a constant irradiation time, or a constant irradiation energy is reached. The light output device according to claim 12, wherein contaminants are removed.