JPH0761829A - Synthetic quartz glass optical member and its production - Google Patents

Abstract

PURPOSE:To provide an optical member efficiently and selectively cutting VUV light of <= approximately 200nm and good in transmittance on the side of longer wavelengths than a transmitting limit wavelength, and to provide a method for producing the same. CONSTITUTION:An optical member comprises synthetic quartz glass having metal impurity contents of <=50ppb, an internal transmittance of >=99.9% at 260-700nm, a transmitting limit wavelength of <=250nm and a wavelength inclination width of <=400nm.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to, for example, ozone-free U.
The present invention relates to a synthetic quartz glass optical member used in a V (ultraviolet) lamp, an optical filter for UV / VUV (vacuum ultraviolet) region, and the like, and a method for manufacturing the same. More specifically, the present invention relates to a synthetic quartz glass optical member that efficiently and selectively cuts VUV light of about 200 nm or less and has high heat resistance, and a method for manufacturing the same.

[0002]

2. Description of the Related Art Conventionally, optical filters have been targeted in the visible range. Colored glass is used for the optical filter. Colored glass is based on the glass composition that becomes F
e, Ni, Co, and other transition metals, Nd, Pr, Er,
It contains a rare earth element such as Ho as a colorant, and its spectral transmittance is adjusted by controlling the redox reaction under melting conditions and colloidizing dispersed particles smaller than the wavelength of light under heat treatment conditions. . When the colored glass is used as an optical filter, particularly as a sharp cut filter defined by JIS B7113 (wavelength inclination width of 35 nm, average transmittance of 85% or more), the performance is wavelength inclination width, transmission limit wavelength, average transmission. Expressed as a rate. As shown in Fig. 2, the wavelength inclination width means that the transmittance near the absorption edge is 72%.
It is displayed at an interval between the wavelength A of 5% and the wavelength B of 5%.
The transmission limit wavelength represents a wavelength corresponding to the center of the wavelength gradient width. Further, the average transmittance is an average value of the transmittances from the wavelength A to 700 nm.

As an optical filter having a wavelength shorter than the visible range, there is lead glass colored glass containing Ti4 +, Ce4 +, etc., having a transmission limit wavelength of 400 nm or less. Further, for ultraviolet use, phosphate or silicate glass containing few impurities such as Fe is often used, but the ultraviolet limit transmittance is the shortest wavelength, and the filter No. It is 220 nm of UV22. Therefore, there is substantially no glass material for a filter that selectively cuts or transmits light having a wavelength shorter than that.

[0004]

As described above, the transmission limit wavelength of the filter-glass is the shortest and the filter-No. It is about 220 nm of UV22. In addition, the glass composition that is the base of the colored glass used in the ultraviolet region is mostly phosphate or silicate glass, and Corex, Uv
Borate glass such as iol, Vita, or Lindeman glass. The transmission limit wavelength of the filter glass having these base glass compositions is 218 in Corex.
nm, 268 nm for Uviol, 252 nm for Vita
It is a degree.

Therefore, it is possible to construct a filter glass having a short transmission limit wavelength by using quartz glass as a base. For example, in the case of fused silica glass, the transmission limit wavelength is about 210 nm. However, in the fused silica glass synthesized by the Bernoulli method mainly using quartz or silica as a raw material, for example, Al, Fe, Ti, N
Inevitably, 0.1 to several ppm of the impurity metal element such as a is contained. Therefore, the transmittance of about 250 nm or more becomes low depending on the concentration of these impurities, and the transmittance on the long wavelength side becomes lower than the original transmission limit wavelength (210 nm).
In addition to the 250 nm absorption band, there are many absorption bands that depend on structural defects, etc., and the internal transmittance on the longer wavelength side than the transmission limit wavelength decreases, and the performance as an optical filter decreases. Furthermore, it is difficult to obtain a sharp cut filter because the wavelength tilt width is wide.

The present invention solves such a problem and provides about 2
Efficiently and selectively cut VUV light of 00 nm or less,
It is an object of the present invention to provide an optical member having a good transmittance on a wavelength side longer than a transmission limit wavelength and a manufacturing method thereof.

[0007]

Therefore, the present inventors have
As a base glass composition, it was considered to use a synthetic quartz glass in which each metal impurity is 50 ppb or less and which has a good internal transmittance of 260 nm or more. As described above, metal impurities reduce the transmittance of 250 nm or more, but by setting the metal impurity concentration of synthetic quartz glass to 50 ppb or less,
The internal transmittance on the longer wavelength side than the transmission limit wavelength can be set to 99.9% or more. The original transmission limit wavelength of synthetic quartz glass is about 160 nm.

Therefore, the present inventors have conducted extensive studies for many years on the relationship between the transmittance characteristics of synthetic quartz glass and the synthesis conditions and heat treatment conditions, and as a result, have found the following. 250 nm
In the method for producing quartz glass that produces the following absorption bands, the synthetic quartz glass material is subjected to heat treatment at 800 ° C. or higher in hydrogen gas or other reducing gas or in vacuum, so that the center of 175 nm (7.1 eV) A relatively broad absorption band having a half-value width of about 1.05 eV as a wavelength is generated.
This absorption band increases as the processing temperature rises and the processing time increases. When a synthetic quartz glass material is heat-treated at 1000 to 1800 ° C. in hydrogen gas, other reducing gas, inert gas or vacuum using a carbon container or the like, the same absorption band is produced. When synthesizing a synthetic quartz glass material by the flame hydrolysis method, an absorption band similar to that obtained by synthesizing in a reducing atmosphere is generated.

Therefore, according to the present invention, according to the above-mentioned manufacturing method,
Each metallic impurity consists of synthetic quartz glass with 50 ppb or less,
The present invention provides a synthetic quartz glass optical member having an internal transmittance of 99.9% or more at 260 nm to 700 nm, a transmission limit wavelength of 250 nm or less, and a wavelength inclination width of 40 nm or less. Here, the internal transmittance refers to a spectral transmittance that does not include reflection loss of optical glass (quoted from Japan Optical Glass Industry Association Standard JOGIS17).

Further, the transmission limit wavelength of the conventional optical filter is determined by the composition of glass, whereas in the present invention, it is due to the absorption band formed between 160 and 250 nm. From this, by adjusting the processing conditions, it became possible to control the transmission limit wavelength of the optical filter to an arbitrary value between 160 and 250 nm.

Therefore, according to the present invention, the transmission limit wavelength is 160 to 250 n by adjusting the processing conditions during the heat treatment.
The present invention provides a method for producing a synthetic quartz glass optical member, which is characterized by setting an arbitrary value of m.

[0012]

From the above facts, the inventors have found a method of controlling the transmittance of 200 nm or less by heat-treating synthetic quartz glass in hydrogen gas and other reducing gases (for example, CH ₄ ) or in vacuum. If this is utilized, a synthetic quartz glass optical member having a desired transmission limit wavelength can be manufactured by optimizing the treatment temperature, the treatment time, the synthesis conditions and the like.

When the treatment is carried out in a hydrogen gas atmosphere, the concentration of 99% or more is desirable from the viewpoint of absorption band generation efficiency or safety because hydrogen is a combustible gas. In particular, the lower the oxygen concentration, the better. As described above, heat treatment of synthetic quartz glass with hydrogen gas produces 175 nm (7.1 eV).
A comparatively broad half-value width of about 1.05 eV
A strong absorption band is generated. Since this phenomenon also occurs in other reducing gas atmospheres, it is considered that the phenomenon is generated by the reduction reaction of the SiO ₂ network.

Assuming from the situation, the attribution of this absorption band is that ≡Si-Si-Si≡ or = Si: (Silico
n Lone Pair Center: SLPC). ≡Si-Si-Si≡ is said to be produced by performing the soot sintering process in a vacuum during the production of VAD quartz glass, and since it is black even by visual observation, Si clusters. -Is also proposed to be generated (* 1 Awazu et al. 37th Joint Lecture on Applied Physics 29
P-ZC-16 (1990.3)). Also, = Si: (SLPC) is Si
It is considered to be generated by sintering O ₂ soot in a hydrogen atmosphere (* 2 M. Kohketsu et. JJ of Appl. Phys.
vol.28, No.4, April, 1989, pp.615-621). SLPC is 250
This is considered to be the cause of the nm absorption band (B ₂ β), and O = Si gas molecules have absorption bands at 180, 250, and 325 nm, and therefore it is predicted that absorption bands other than 250 nm will also be generated.
Assuming that ≡Si-Si-Si≡ or = Si: (SLPC), the following four reaction equations are possible.

[0015]

[Chemical 1]

However, ≡Si-Si-Si≡ is
The fact that it cannot be detected by an instrumental analyzer such as ESCA, that the increase of H ₂ O presumed to be a by-product has not been detected by IR, while SLPC should simultaneously generate the 250 nm band and the 325 nm band. However, there are many unclear points such as not being detected in the experiment of the present invention. However, judging from the experimental results of the present invention, any S
It seems that the reducing substance of the iO ₂ network is the cause. The typical UV or VUV absorption band of quartz glass is 163 nm (≡Si-Si≡), 215 nm.
nm (E 'center), 225 nm (E' ₂ center), 250
nm (B ₂ α: ≡Si-X-Si≡ (X: oxygen vacancy),
B ₂ β: O ₂ = Si :), 260 nm (NBOHC or Si—O ^{−, etc.} unknown), 325 nm (oxygen excess defect, or Cl-related), 165 nm or less (OH group), etc. exist, but these are controlled. In this case, the transmittance in the UV or VUV range can be controlled, but it is desirable to use the 175 nm absorption band according to the present invention in view of the ease of control and the stability of the absorption band. Other absorption bands can be used depending on the wavelength to be used.

Next, actual experimental results and examples will be described. First, FIG. 1 shows a graph showing the processing temperature dependence of the transmittance by the heat treatment in a hydrogen atmosphere. sample,
A double-sided polishing product having a thickness of 10 mm was used. Hydrogen gas 100%
Atmosphere, 60h under 6 atm, the sample after treatment with 500 to 1100 ° C., and untreated, is a transmission spectrum of the reflection loss include the samples treated under 1000 ° C. N ₂ atmosphere. It can be seen that the 175 nm absorption band is large due to the increase in the processing temperature, and that almost no absorption occurs in the N ₂ atmosphere. The difference between the effects of H ₂ and N ₂ seems to be due to the difference in diffusion rate and reducing power. It has been found that absorption of N ₂ occurs relatively near the surface by long-time treatment at a temperature of 1100 ° C. or higher. It has also been confirmed that the same absorption occurs even when treated in a carbon container.
However, from the viewpoint of controlling the amount of absorption, a hydrogen atmosphere is desirable. The OH group concentration of the sample used in the experiment is about 130.
Since it is 0 ppm, the transmittance is almost zero on the wavelength side slightly longer than 160 nm. Therefore, even if the 163 nm band is generated, it is not observed in this case.

Next, the shape of the generated absorption band will be analyzed. The analyzed graph is shown in FIG. The horizontal axis represents photon energy (eV), and the vertical axis represents absorption coefficient (α cm ⁻¹ ). The absorption coefficient α is a numerical value calculated by the ratio of the transmittance of the sample treated at each temperature (1100, 1000, 900 ° C.) to the transmittance of the untreated 10 mm sample. Strictly speaking, the expression is an apparent absorption coefficient. □ (1100 ° C), + (1000 ° C), ◇ (90
(0 ° C.) is plotted for each symbol. On the energy side higher than 7.5 eV, the transmittance of the unprocessed sample is also low, and therefore contains many error components. Further, assuming that the shape of this absorption band is a Gaussian type, a curve calculated at a peak position of 7.1 eV and a half value width of 1.05 eV is shown by a dotted line. Considering the error component on the high energy side, it is considered that the fit is fairly good. This can be judged to be an almost single absorption band. Therefore, the processing temperature dependency (FIG. 4) and the processing time dependency (FIG. 5) are considered to have a very good linear relationship. This shows that controlling the amount of absorption is very simple. On the contrary, if this absorption is suppressed, 2
This is a technique that is useful for increasing the transmittance near 00 nm. In order to increase the transmittance, it may be manufactured under the condition that this absorption band is not generated.

Next, the occurrence of absorption due to the synthesis conditions will be described. Synthetic quartz glass is generally manufactured by a method in which SiCl ₄ is introduced into an oxyhydrogen flame burner to form SiO ₂ fine particles and, at the same time, a glass lump is obtained by being deposited on a rotating target. To be FIG. 5 shows the flow rate ratio of O ₂ / H ₂ supplied to the oxyhydrogen burner at the time of synthesis of 0.1 to 0.2.
FIG. 6 shows the transmission spectra of the samples synthesized under (hydrogen excess) and 0.4 to 0.5 (normal conditions). From FIG. 6 it can be seen that this absorption is the same as the absorption generated during hydrogen heat treatment.

Regarding the method of generating absorption, the advantages and disadvantages of the method by heat treatment and the method by synthesis are compared. Synthesis is superior in terms of three-dimensional homogeneity of transmittance. In the case of heat treatment, the absorption coefficient near the surface becomes large because it is affected by the diffusion of by-products due to the reduction reaction. Therefore, the homogeneity is slightly inferior. However, the heat treatment method is superior in terms of cost, transmittance control accuracy, and simplicity. From the viewpoint of preventing surface devitrification (crystallization), the treatment temperature is preferably 1100 ° C. or lower or 1800 ° C. or higher. Further, the treatment at 1900 ° C. or higher should be avoided because the sublimation of SiO ₂ becomes remarkable.

[0021]

Example 1 Standard synthetic quartz glass in a hydrogen atmosphere,
175n by processing at 6 atmospheres, 1100 ° C for 600h
Absorption coefficient α = 20 cm ^-1 at m (7.1 eV), and its absorption band has a Gaussian shape and a half-value width of about 1.05 eV.
It was possible to obtain quartz glass of.

[0022]

Example 2 A standard synthetic quartz glass was placed in a hydrogen atmosphere,
175nm by 6 atmospheric pressure, 1800 ℃, 6h treatment
Absorption coefficient α at (7.1 eV) = 200 cm ^-1 , and its absorption band has a Gaussian shape with a half value width of about 1.05 eV.
It was possible to obtain quartz glass of.

[0023]

Example 3 A standard synthetic quartz glass was used in a hydrogen atmosphere.
175nm by 6 atmospheric pressure, 1100 ℃, 24h treatment
Absorption coefficient at (7.1 eV) α = 800 cm ^-1 , and its absorption band is Gaussian type with a half value width of about 1.05 eV
It was possible to obtain quartz glass of.

[0024]

Example 4 Standard synthetic quartz glass was converted into methane (C
H ₄ ) atmosphere at 6 atmosphere, 1100 ° C., 600 h, absorption coefficient α = 5 at 175 nm (7.1 eV)
It was possible to obtain quartz glass having a cm ⁻¹ and absorption band shape of Gaussian type and a half width of about 1.05 eV. The lower absorption coefficient than hydrogen atmosphere is considered to be due to the diffusivity.

[0025]

Example 5 Standard synthetic quartz glass in a carbon container
In Ar atmosphere at 6 atm, 1800 ° C. for 60 h
Therefore, the absorption coefficient at 175 nm (7.1 eV) α = 50
cm ^-1, And the shape of its absorption band are Gaussian type and half width
It was possible to obtain quartz glass of about 1.05 eV. Like this
In addition, even if the atmosphere is not reducing, the surface is
Since they are in contact with each other, SiO₂Is reduced and an absorption band is generated
It

FIG. 7 shows a graph comparing the transmission spectra of the silica glass of Examples 1 to 5 with the transmission spectra of silica glass having an OH group of 20 ppm, which is close to the theoretical transmittance, and a normally synthesized OH group of 1300 ppm. Since those having α = 800 cm ⁻¹ hardly transmit light having a short wavelength of 220 nm or less, they can be sufficiently used as ozone-free UV lamps and window materials thereof. Further, it has been found that by optimizing the conditions, it is possible to obtain a UV / VUV light cut filter and a window material having desired transmittance characteristics. Further, since the absorption band is almost single and it is a Gaussian type, the curve becomes a curve with a smooth transmission, and it seems that it is easy to use as a filter.

[0027]

EFFECTS OF THE INVENTION According to the method for producing quartz glass of the present invention, hydrogen gas, a reduction heat treatment condition using a carbon container or the like, a vacuum heat treatment or an absorption band formed by synthesis under hydrogen excess is utilized. It is possible to manufacture quartz glass with adjusted transmittance in the UV, UV, and VUV regions. That is, by adjusting the conditions of heat treatment and synthesis, quartz glass having a desired transmission spectrum can be obtained. In addition, this method uses Na, Al,
Unlike the method of doping an impurity metal element such as Fe, etc., it has the feature that only the transmittance can be changed without lowering the purity. Utilizing this technique yields the significance and characteristics listed below, among others. Since there is no absorption band other than near the absorption edge in the light transmission region used, very good characteristics can be obtained as a sharp cut filter in the UV and VUV regions.

For example, α = 800 cm-1 shown in FIG.
In the case of, the transmission limit wavelength is 228 nm, the wavelength inclination width is 13 n
m, and an average transmittance of 90% or more is obtained. Further, by decreasing α, the wavelength inclination width and the average transmittance are the same, and the transmission limit wavelength can be arbitrarily selected up to about 160 nm. The transmission limit wavelength is 1 for OH groups.
Since it has absorption around 60 nm, it also depends on the OH group concentration. For example, when the OH group is 1200 ppm, the selection range of the transmission limit wavelength is about 170 to 250 nm.
Below 100 ppm, the transmission limit wavelength is about 160-
It becomes selectable at 250 nm. This technology uses optical measuring instruments such as a spectrophotometer, optical filters used in various optical systems, and 220 nm to prevent the generation of ozone.
It can be used for the following purposes such as cutting UV / VUV light. With this technique, in the UV and VUV regions of 300 nm or less, the transmittance of the wavelength used by the light source can be freely adjusted within the range of the theoretical transmittance of quartz glass and within the range of internal transmittance of 0 to 100%. In this technique, the transmittance of a specific wavelength can be arbitrarily adjusted and selected depending on the application such as an optical lens. For example, unnecessary short wavelength light can be cut by the lens itself. Since the cause of the generation of the absorption band in the VUV region is known, by suppressing the generation of this absorption band, it is possible to meet the requirement of high transmittance of 99% or more.

Furthermore, this method can also be applied to quartz glass manufactured by other manufacturing methods such as fused silica glass. Further, by applying this fact and controlling the oxidation-reduction reaction under the synthesis condition or the heat treatment condition, it can be useful for increasing the transmittance in the VUV region of the material. In addition, from the viewpoint of preventing the pollution of the synthesis equipment that should be of high purity and the cost of equipment investment, it is usually the case that impurities such as Ti and Na are doped to adjust the transmittance. Is not done.

By modifying or adjusting the quality by this method, the application of the synthetic quartz glass is expanded, resulting in cost reduction.

[Brief description of drawings]

FIG. 1 is a graph showing the dependency of transmittance on the processing temperature and the atmosphere by the heat treatment in a hydrogen atmosphere.

FIG. 2 is a graph for explaining terms indicating characteristics of an optical filter.

FIG. 3 is a graph in which measured values at each processing temperature are plotted with a horizontal axis representing photon energy and a vertical axis representing an absorption coefficient, and compared with a Gaussian model.

FIG. 4 is a graph plotting the behavior of the absorption coefficient α according to the processing temperature in the hydrogen atmosphere heat treatment.

FIG. 5 is a graph plotting the time dependence of absorption coefficient α by heat treatment in a hydrogen atmosphere.

FIG. 6 is a graph showing the behavior of the transmittance depending on the synthesis conditions.

FIG. 7 is a transmission spectrum graph comparing the transmittances of quartz glass adjusted to each absorption coefficient α and obtained by the method for producing quartz glass of the present invention, and ordinary quartz glass.

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[Procedure amendment]

[Submission date] November 8, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

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[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

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[Correction content]

As an optical filter having a wavelength shorter than the visible region, there is lead glass or colored glass containing Ti ⁴⁺ , Ce ^4+, etc., having a transmission limit wavelength of 400 nm or less. Further, phosphate or silicate glass containing few impurities such as Fe is often used for ultraviolet light, but the ultraviolet limit transmittance is the shortest, and the filter No. It is 220 nm of UV22. Therefore, there is substantially no glass material for a filter that selectively cuts or transmits light having a wavelength shorter than that.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0011

[Correction method] Change

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Therefore, according to the present invention, the processing conditions for the heat treatment are
By adjusting the atmosphere in the preliminary synthesis, by setting the transmission threshold wavelength to an arbitrary value of 160～250Nm, or
In addition, in the UV and VUV regions of 300 nm or less, the internal transmission
The present invention provides a method for manufacturing a synthetic quartz glass optical member, which is characterized in that the excess ratio is set to an arbitrary value within the range of 0 to 100% .

[Procedure amendment 4]

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Next, actual experimental results and examples
Explain.First, Fig. 1 shows the permeation by hydrogen atmosphere heat treatment.
It is a graph which showed the processing temperature and atmosphere dependence of the rate.
As the sample, a double-side polished product having a thickness of 10 mm was used. hydrogen
100% gas atmosphere, 6 hours under 60 hours, 500-11
Samples after treatment at 00 ° C and untreated, 100
0 ° C N₂Including reflection loss of sample processed in atmosphere
It is a transmission spectrum. As the processing temperature rises, 17
Large generation of 5 nm absorption band, and N ₂atmosphere
It turns out that absorption hardly occurs in. H₂And N₂Of the effect of
The difference may be due to the difference in diffusion rate and reducing power. 110
N by treating for a long time at high temperature above 0 ℃ ₂But relatively table
It is known that absorption occurs near the plane. In addition,
Even if treated in a carbon container, the same absorption may occur.
It has been confirmed. However, in terms of controlling the amount of absorption
Is preferably a hydrogen atmosphere. O of the sample used for the experiment
Since the H group concentration is about 1300 ppm, from 160 nm
The transmittance is almost zero on the slightly longer wavelength side. others
Therefore, even if the 163 nm absorption band is generated, this
Is not observed.

[Procedure Amendment 5]

[Document name to be amended] Statement

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Next, the occurrence of absorption due to the synthesis conditions will be described. Synthetic quartz glass is generally produced by introducing SiCl ₄ into an oxyhydrogen flame burner to form SiO ₂ fine particles and at the same time depositing on a rotating target to obtain a glass gob. Oxyhydrogen flame during synthesis
The O ₂ / H ₂ flow rate ratio supplied to the burner is 0.1 to 0.2
(Hydrogen excess) and 0.4-0.6 (normal conditions)
Figure 6 shows the transmission spectra of each sample.
You From FIG. 6 it can be seen that this absorption is identical to the absorption generated during hydrogen heat treatment.

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[0023]

Example 3 A standard synthetic quartz glass was used in a hydrogen atmosphere.
175nm by 6 atmospheric pressure, 1800 ℃ , 24h treatment
Absorption coefficient at (7.1 eV) α = 800 cm ^-1 , and its absorption band is Gaussian type with a half value width of about 1.05 eV
It was possible to obtain quartz glass of.

[Procedure Amendment 7]

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FIG. 7 shows a graph comparing the transmission spectra of the silica glass of Examples 1 to 3 with the transmission spectra of silica glass having an OH group of 20 ppm and a normally synthesized OH group of 1300 ppm, which are close to the theoretical transmittance. Since those having α = 800 cm ⁻¹ hardly transmit light having a short wavelength of 220 nm or shorter, they can be sufficiently used as ozone-free UV lamps and window materials thereof. It was also found that by optimizing the conditions, it is possible to obtain a UV / VUV light cut filter and a window material having desired transmittance characteristics. Also, since the absorption band is almost single and it is of Gaussian type, the transmission curve becomes a smooth curve, and it seems that it is easy to use as a filter.

[Procedure Amendment 8]

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[Correction method] Change

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For example, in the case of α = 800 cm ⁻¹ shown in FIG. 7, the transmission limit wavelength is 228 nm, the wavelength inclination width is 13 nm,
A quality with an average transmittance of 90% or more is obtained. Also, α
By decreasing the wavelength inclination width, the average transmittance equal, the transmission threshold wavelength can be selected arbitrarily to about 160 nm. In addition, the transmission limit wavelength is 160
Since it has absorption near nm, it also depends on the OH group concentration. For example, when the OH group is 1200 ppm, the selection range of the transmission limit wavelength is about 170 to 250 nm.
Below 00 ppm, the transmission limit wavelength is about 160-25.
It becomes selectable at 0 nm. This technique, and optical measuring instruments such as a spectrophotometer, can be utilized various and optical filters used in the optical system, the 220nm or less for preventing the generation of ozone, in applications such as cutting the UV · VUV light . With this technique, in the UV and VUV regions of 300 nm or less, the transmittance of the wavelength used by the light source can be freely adjusted within the range of the theoretical transmittance of quartz glass and the internal transmittance of 0 to 100%. In this technique, the transmittance of a specific wavelength can be arbitrarily adjusted and selected depending on the application such as an optical lens. For example, unnecessary short wavelength light can be cut by the lens itself. Since the cause of the generation of the absorption band in the VUV region is known, it is possible to meet the requirement of high transmittance of 99% or more by suppressing the generation of this absorption band.

 ─────────────────────────────────────────────────── ─── Continued Front Page (72) Inventor Hiroyuki Hiraiwa 3 2-3 Marunouchi, Chiyoda-ku, Tokyo Inside Nikon Corporation

Claims (6)

[Claims] 1. An internal transmittance of 260 nm to 700 nm of 9 made of synthetic silica glass in which each metal impurity is 50 ppb or less.
A synthetic quartz glass optical member having a transmittance limit wavelength of 9.9% or more, a wavelength of 250 nm or less, and a wavelength inclination width of 40 nm or less. 2. A synthetic quartz glass material having metal impurities of 50 ppb or less as a raw material, which is heat-treated in hydrogen gas or other reducing gas or in vacuum to form an absorption band at 250 nm or less. A method of manufacturing a synthetic quartz glass optical member. 3. A heat treatment is carried out in a container having a reducing power, which is made of a synthetic quartz glass material in which each metal impurity is 50 ppb or less and which is provided in hydrogen gas, other reducing gas, inert gas or vacuum. And producing an absorption band at 250 nm or less, a method for producing a synthetic quartz glass optical member. 4. The method for producing a synthetic quartz glass optical member according to claim 3, wherein the container having a reducing power is made of carbon. 5. The method for manufacturing a synthetic quartz glass optical member according to claim 2 or 3, wherein the transmission limit wavelength is 160 to 160 by adjusting the processing conditions during the heat treatment.
A method of manufacturing a synthetic quartz glass optical member, which is set to an arbitrary value of 250 nm. 6. A method for producing a synthetic quartz glass optical member using a synthetic quartz glass material as a raw material, wherein each metal impurity synthesized by a flame hydrolysis method is 50 ppb or less, and the atmosphere during the synthesis of the synthetic quartz glass material is reducible. A method for manufacturing a synthetic quartz glass optical member, characterized in that the transmission limit wavelength is set to an arbitrary value of 160 to 250 nm by adjusting the atmosphere.