JPH0952719A - Production of synthetic quartz glass preform - Google Patents
Production of synthetic quartz glass preformInfo
- Publication number
- JPH0952719A JPH0952719A JP21084595A JP21084595A JPH0952719A JP H0952719 A JPH0952719 A JP H0952719A JP 21084595 A JP21084595 A JP 21084595A JP 21084595 A JP21084595 A JP 21084595A JP H0952719 A JPH0952719 A JP H0952719A
- Authority
- JP
- Japan
- Prior art keywords
- quartz glass
- synthetic quartz
- temperature
- distribution
- refractive index
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C3/00—Glass compositions
- C03C3/04—Glass compositions containing silica
- C03C3/06—Glass compositions containing silica with more than 90% silica by weight, e.g. quartz
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B19/00—Other methods of shaping glass
- C03B19/14—Other methods of shaping glass by gas- or vapour- phase reaction processes
- C03B19/1453—Thermal after-treatment of the shaped article, e.g. dehydrating, consolidating, sintering
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C4/00—Compositions for glass with special properties
- C03C4/0071—Compositions for glass with special properties for laserable glass
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C4/00—Compositions for glass with special properties
- C03C4/0085—Compositions for glass with special properties for UV-transmitting glass
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2201/00—Type of glass produced
- C03B2201/06—Doped silica-based glasses
- C03B2201/20—Doped silica-based glasses doped with non-metals other than boron or fluorine
- C03B2201/21—Doped silica-based glasses doped with non-metals other than boron or fluorine doped with molecular hydrogen
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C2201/00—Glass compositions
- C03C2201/06—Doped silica-based glasses
- C03C2201/20—Doped silica-based glasses containing non-metals other than boron or halide
- C03C2201/21—Doped silica-based glasses containing non-metals other than boron or halide containing molecular hydrogen
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
- C03C2203/00—Production processes
- C03C2203/50—After-treatment
- C03C2203/52—Heat-treatment
- C03C2203/54—Heat-treatment in a dopant containing atmosphere
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Chemical & Material Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Physics & Mathematics (AREA)
- Thermal Sciences (AREA)
- Manufacturing & Machinery (AREA)
- Optics & Photonics (AREA)
- Glass Melting And Manufacturing (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は合成石英ガラス母材
の製造方法に関し、より詳細には紫外領域から赤外領域
にわたる広い波長領域における光を利用した機器のレン
ズ、ミラー、プリズム、窓部材等の光学部品の形成に用
いられる合成石英ガラス材の原料となる合成石英ガラス
母材の製造方法に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a synthetic quartz glass base material, and more particularly to a lens, a mirror, a prism, a window member, etc. of a device utilizing light in a wide wavelength range from the ultraviolet region to the infrared region. The present invention relates to a method for manufacturing a synthetic quartz glass base material which is a raw material of a synthetic quartz glass material used for forming an optical component.
【０００２】[0002]
【従来の技術】合成石英ガラスは約１５０ｎｍ〜約５μ
ｍという広い波長範囲で光を透過するため応用範囲が広
いこと、熱膨張係数が小さいために光軸のずれが小さく
高精度の光学系を構成できること、耐熱性が高いために
広い温度範囲で使用できること、高純度な二酸化ケイ素
であるために高エネルギーの光を照射しても損傷を受け
にくいこと等、数々の非常に優れた特性を有している。2. Description of the Related Art Synthetic quartz glass is about 150 nm to about 5 μm.
Since it transmits light in a wide wavelength range of m, it has a wide range of applications, and because of its small coefficient of thermal expansion, it can be used in a wide temperature range due to its high heat resistance and high precision optical system. It has a number of very excellent characteristics, such as being able to do, and being high-purity silicon dioxide, being less likely to be damaged even when irradiated with high-energy light.
【０００３】このような優れた特性を生かし、例えば紫
外領域から赤外領域にわたる広い波長領域における光を
利用した機器のレンズ、ミラー、プリズム、窓部材等の
光学部品等に用いられている。Taking advantage of such excellent characteristics, it is used for optical parts such as lenses, mirrors, prisms, window members, etc. of equipment utilizing light in a wide wavelength range from the ultraviolet region to the infrared region.
【０００４】これらの光学部品の形成に用いられる石英
ガラス材料には、種々の特性が要求されるが、特に屈折
率の均質性、及び使用波長での耐光性が高いこと（光照
射後に透過率が低下しにくいこと）等が要求される。The quartz glass material used for forming these optical parts is required to have various characteristics, but in particular, the homogeneity of the refractive index and the high light resistance at the wavelength used (the transmittance after light irradiation are high). Is less likely to decrease).
【０００５】このような厳しい条件に適合可能な石英ガ
ラスとして、合成石英ガラスが挙げられる。一般的に合
成石英ガラスという呼び名は、出発原料として天然のシ
リカ原料を用いていない全ての石英ガラスに適用される
が、この合成石英ガラスを製造する方法としては、種々
の方法が存在する。従って、原料の純度や製造方法に起
因して、製造された合成石英ガラスの不純物元素濃度
（金属元素濃度、非金属元素濃度）や欠陥濃度等も様々
なグレードのものが存在し、すべての合成石英ガラスが
理想的な透過光学系用のガラス材料となり得るわけでは
ない。Synthetic silica glass is an example of silica glass that can meet such severe conditions. Generally, the name of synthetic quartz glass is applied to all quartz glass that does not use a natural silica raw material as a starting material, but there are various methods for producing this synthetic quartz glass. Therefore, there are various grades of impurity element concentration (metal element concentration, non-metal element concentration), defect concentration, etc. in the synthetic quartz glass produced due to the purity of the raw materials and the production method. Quartz glass cannot be an ideal glass material for a transmission optical system.
【０００６】合成石英ガラスの製造法には大別して気相
法と液相法があり、光学系に用いられる材料の製造方法
としては気相法が主流であるが、この気相法も直接合成
法、プラズマＣＶＤ法、気相軸付け法（ＶＡＤ法）等の
種類があり、原料や製造方法に起因して合成石英ガラス
中における金属等の不純物、ＯＨ基、Ｃｌ、Ｈ2 、Ｏ
2 、酸素過剰欠陥、酸素欠乏欠陥、環構造欠陥等の濃度
が異なる。これらの不純物や欠陥等の濃度は、合成石英
ガラスの光吸収、蛍光、屈折率等の光学特性に大きな影
響を及ぼすことが知られている。[0006] The synthetic quartz glass is roughly classified into a vapor phase method and a liquid phase method, and the vapor phase method is the main method for producing a material used for an optical system. This vapor phase method is also directly synthesized. Method, plasma CVD method, vapor phase axis method (VAD method), etc., and impurities such as metal in synthetic quartz glass, OH groups, Cl, H 2 , O due to the raw material and manufacturing method.
2. The concentration of oxygen excess defects, oxygen deficiency defects, ring structure defects, etc. is different. It is known that the concentrations of these impurities and defects have a great influence on the optical properties of the synthetic quartz glass such as light absorption, fluorescence, and refractive index.
【０００７】[0007]
【発明が解決しようとする課題】例えば前記ＶＡＤ法
は、バーナーからケイ素化合物、水素、酸素などの原料
ガスを鉛直に懸下した種棒に向けて供給し、前記ケイ素
化合物を酸素−水素火炎中で加水分解させて生成させた
石英ガラスの微粒子を石英製等の種棒の下端部に付着、
堆積させて多孔質合成石英ガラスを形成した後、加熱す
ることにより透明ガラス化する合成石英ガラスの製造法
であるが、そのためにケイ素化合物として四塩化ケイ素
を使用した場合には、塩素やＯＨ基等が合成石英ガラス
内に残留し、その濃度が不均一になり易く、これらの不
純物に起因して屈折率等に分布が生じるという問題があ
った。For example, in the VAD method, a raw material gas such as a silicon compound, hydrogen, and oxygen is supplied from a burner toward a vertically suspended seed rod, and the silicon compound is supplied in an oxygen-hydrogen flame. The fine particles of quartz glass produced by hydrolysis with are attached to the lower end of a seed rod made of quartz,
This is a method for producing synthetic quartz glass in which porous synthetic quartz glass is deposited and then heated to form transparent vitreous silica. However, when silicon tetrachloride is used as the silicon compound for this purpose, chlorine or OH groups are used. And the like remain in the synthetic quartz glass, the concentration thereof is likely to be non-uniform, and there is a problem in that the refractive index and the like are distributed due to these impurities.
【０００８】また、通常、透明ガラス化は１４２０〜１
６００℃の温度範囲で行うが、その後の徐冷時の合成石
英ガラス体の内部と外部とにおける冷却速度の差に起因
して、屈折率に分布が生じる。そして、通常は、主とし
てＯＨ基の分布によって生じる屈折率の分布と透明ガラ
ス化後の徐冷によって生じる屈折率分布とが重なり合う
ため、より大きな屈折率分布を生じ易いという問題があ
った。Further, normally, the vitrification is 1420 to 1
Although the temperature is set to 600 ° C., the refractive index is distributed due to the difference in cooling rate between the inside and the outside of the synthetic quartz glass body during the subsequent slow cooling. Usually, since the distribution of the refractive index mainly caused by the distribution of OH groups and the refractive index distribution caused by the gradual cooling after the transparent vitrification overlap, there is a problem that a larger refractive index distribution is likely to occur.
【０００９】このような不純物の残留濃度分布に起因す
る屈折率分布と、製造過程の冷却条件等の熱履歴に起因
する屈折率分布とを相反する分布として消去し合うよう
に不純物濃度や加熱後の冷却速度を調整し、実際の屈折
率分布が小さく、良好な品質の光学用石英ガラスを得る
方法が提案されている（特開平２−１０２１３９号公
報、特開平２−２３９１２７号公報等）。[0009] The refractive index distribution due to such a residual concentration distribution of impurities and the refractive index distribution due to thermal history such as cooling conditions in the manufacturing process are erased as contradictory distributions so that the impurity concentration and after heating may be erased. There is proposed a method of adjusting the cooling rate to obtain an optical quartz glass having a small actual refractive index distribution and good quality (JP-A-2-102139, JP-A-2-239127, etc.).
【００１０】前記特開平２−１０２１３９号公報に記載
された発明においては、ガラスの中央部分にＯＨ基の極
小濃度域を存在させるとともに、周辺部に近づくにつれ
て徐々に高濃度となるＯＨ基濃度分布を形成する。この
とき、前記ＯＨ基濃度分布に起因する屈折率分布は中央
部分で極大値を有し、周辺部に近づくにつれて低下する
分布（以下、凸型分布と記す）をなしている。一方、前
記ＯＨ基濃度分布に起因する屈折率分布を打ち消すよう
に、熱処理条件を選択することによる屈折率分布を形成
する。すなわち、８００〜１３００℃の範囲に所定時間
加熱した後、所定の速度で徐冷する方法により仮想温度
分布をコントロールし、この仮想温度分布に起因する中
央部分に極小値を有し、周辺部に近づくにつれて大きく
なる屈折率分布（以下、凹型分布と記す）を形成する。
このような相反する不純物濃度に起因する屈折率分布と
仮想温度分布に起因する屈折率分布を形成することによ
り、総合的に屈折率分布が小さく、良好な品質を有する
光学用合成石英ガラスを得ることができることが前記公
報に記載されている。In the invention described in the above-mentioned Japanese Patent Laid-Open No. 2-102139, a minimum concentration range of OH groups exists in the central portion of the glass, and the concentration distribution of OH groups gradually increases toward the peripheral portion. To form. At this time, the refractive index distribution due to the OH group concentration distribution has a maximum value in the central portion and decreases as it approaches the peripheral portion (hereinafter referred to as a convex distribution). On the other hand, a refractive index distribution is formed by selecting heat treatment conditions so as to cancel the refractive index distribution due to the OH group concentration distribution. That is, the virtual temperature distribution is controlled by a method of heating in the range of 800 to 1300 ° C. for a predetermined time and then slowly cooling at a predetermined rate, and the virtual temperature distribution has a minimum value in the central portion and a peripheral portion in the peripheral portion. A refractive index distribution (hereinafter, referred to as a concave distribution) that increases as the distance approaches is formed.
By forming the refractive index distribution due to the contradictory impurity concentration and the refractive index distribution due to the fictive temperature distribution as described above, an optical synthetic quartz glass having a small refractive index distribution and good quality is obtained. It is described in the above publication that this can be done.
【００１１】また、特開平２−２３９１２７号公報に記
載された発明においては、ＯＨ基濃度と塩素濃度とに起
因した屈折率分布を凸型分布とし、前記凸型の屈折率分
布を打ち消すように仮想温度分布をコントロールするこ
とにより凹型の屈折率分布を形成し、総合的に屈折率分
布を小さく、良好な品質の光学用合成石英ガラスを得る
ことができることが記載されている。Further, in the invention described in JP-A-2-239127, the refractive index distribution due to the OH group concentration and the chlorine concentration is made to be a convex type distribution so that the convex type refractive index distribution is canceled. It is described that by controlling the virtual temperature distribution, a concave type refractive index distribution is formed, and the refractive index distribution is generally small, and a synthetic quartz glass for optical use of good quality can be obtained.
【００１２】しかしながら、前記したように、通常の方
法で製造した合成石英ガラス中のＯＨ基濃度と塩素濃度
は、ガラス塊の内部ほど残留し易いため、いずれも中央
部分に極大濃度域があり、その周辺部に近づくにつれて
徐々に低濃度となり、前記ＯＨ基濃度分布及び塩素濃度
分布に起因する屈折率分布はいずれも凹型となる。従っ
て、ガラス塊の中央部分に極小値を有するようなＯＨ基
濃度分布及び塩素濃度分布を形成することは難しく、ま
たその濃度分布をコントロールすることは一層難しいた
め、このような合成石英ガラスの製造方法は現実的な方
法ではなく、また仮に製造できたとしても、設備自体が
高価になるため、得られる合成石英ガラスも非常に高価
なものとなるという課題があった。However, as described above, since the OH group concentration and the chlorine concentration in the synthetic quartz glass produced by the usual method are more likely to remain inside the glass lump, both have a maximum concentration region in the central portion, The concentration gradually becomes lower as it approaches the peripheral portion, and both the OH group concentration distribution and the refractive index distribution due to the chlorine concentration distribution are concave. Therefore, it is difficult to form the OH group concentration distribution and the chlorine concentration distribution having a minimum value in the central portion of the glass gob, and it is more difficult to control the concentration distribution. The method is not a realistic method, and even if it can be manufactured, the equipment itself is expensive, so that there is a problem that the obtained synthetic quartz glass is also very expensive.
【００１３】本発明はこのような課題に鑑みなされたも
のであり、屈折率が均一で屈折率分布がほとんどない合
成石英ガラスを得ることが可能な合成石英ガラス母材の
製造方法を提供することを目的としている。The present invention has been made in view of the above problems, and provides a method for producing a synthetic quartz glass preform capable of obtaining a synthetic quartz glass having a uniform refractive index and almost no refractive index distribution. It is an object.
【００１４】[0014]
【課題を解決するための手段】本発明に係る合成石英ガ
ラス母材の製造方法は、気相軸付け法により形成された
多孔質合成石英ガラスに、事前仮焼工程として、１．５
〜５０パスカルの圧力下、１３００〜１４００℃で１〜
５時間の加熱処理を施して密度を均質化し、次に仮焼工
程として、同じ圧力下、１２００〜１３００℃の温度で
１０〜４０時間加熱して水分等を除去した後、０．５〜
５℃／分の速度で昇温し、さらに透明化工程を行い透明
ガラス化することを特徴としている。A method for producing a synthetic quartz glass base material according to the present invention is a method for producing a synthetic quartz glass preform with a porous synthetic quartz glass formed by a vapor phase axial method, in which a preliminary calcination step of 1.5 is performed.
1 to 1300 to 1400 ° C under pressure of -50 Pascal
After heat treatment for 5 hours to homogenize the density, and then as a calcination step, after heating at a temperature of 1200 to 1300 ° C. for 10 to 40 hours under the same pressure to remove water and the like, 0.5 to
It is characterized in that the temperature is raised at a rate of 5 ° C./min, and a transparentizing step is further carried out to obtain transparent glass.
【００１５】[0015]
【発明の実施の形態】上記したように、原料となる高純
度ケイ素化合物としては、例えば四塩化ケイ素が挙げら
れるが、前記原料中の金属不純物の総含有量が０．０５
ｐｐｍ以下、Ａｌの含有量が０．００５ｐｐｍ以下、Ｎ
ａ、Ｋ、及びＬｉの各含有量が０．００８ｐｐｍ以下、
Ｃａ、Ｆｅ、Ｔｉ、Ｃｒ、Ｎｉ、Ｐ、Ｂ、Ｍｇ、Ｃｕ、
Ｚｒ、及びＺｎの各含有量が０．００３ｐｐｍ以下であ
るのが好ましい。BEST MODE FOR CARRYING OUT THE INVENTION As described above, examples of the high-purity silicon compound as a raw material include silicon tetrachloride, and the total content of metal impurities in the raw material is 0.05.
ppm or less, content of Al is 0.005 ppm or less, N
Each content of a, K, and Li is 0.008 ppm or less,
Ca, Fe, Ti, Cr, Ni, P, B, Mg, Cu,
The Zr and Zn contents are preferably 0.003 ppm or less.
【００１６】前記原料中の不純物濃度は、原料をＣＶＤ
炉中で約１０００℃に加熱して基体上に蒸着させ、その
蒸着した金属シリコン中の金属不純物量を放射化分析法
で分析することにより測定することができる。The impurity concentration in the raw material is determined by CVD of the raw material.
It can be measured by heating to about 1000 ° C. in a furnace to vapor-deposit it on a substrate, and analyzing the amount of metal impurities in the vapor-deposited metal silicon by activation analysis.
【００１７】多孔質合成石英ガラスの合成では、特別な
条件は必要でなく、気相軸付け法による通常の酸水素火
炎を用いた加水分解を行えばよい。No special conditions are required for synthesizing the porous synthetic quartz glass, and hydrolysis using a normal oxyhydrogen flame by a vapor phase axial method may be performed.
【００１８】次に、前記工程により得られた多孔質合成
石英ガラス（スート体）を真空下で熱処理等を行って合
成石英ガラス材を製造するが、この合成石英ガラス材の
製造工程は、事前仮焼、仮焼、昇温、及び透明化の工程
による合成石英ガラス母材の製造工程、及び前記母材を
使用して加工等を行った後、加熱成形、冷却、均温化、
冷却により合成石英ガラス製品の製造を行う工程とに分
けられる。Next, the porous synthetic quartz glass (soot body) obtained in the above step is subjected to heat treatment or the like in a vacuum to produce a synthetic quartz glass material. Calcination, calcination, temperature rise, and manufacturing process of synthetic quartz glass preform by the process of clarification, and after performing processing using the preform, heat forming, cooling, soaking,
It is divided into a process of manufacturing a synthetic quartz glass product by cooling.
【００１９】ケイ素化合物の加水分解により得られたス
ート体の空隙は、その分布が不均一で周辺部分に空隙が
多く、中央にいくに従って順次空隙が少なくなってお
り、その密度も周辺部分が小さく、中央に近づくに従っ
て大きくなっている。The voids of the soot body obtained by hydrolysis of the silicon compound have a non-uniform distribution and have many voids in the peripheral portion, and the voids gradually decrease toward the center, and the density is also small in the peripheral portion. , Getting larger toward the center.
【００２０】そこで前記事前仮焼工程により、主として
スート体周辺の最も密度の小さい部分を他の部分と比べ
て急激にその密度を高める操作、すなわち焼きしめを行
って、スート体の密度を均一化させる。この事前仮焼に
より、次工程である仮焼工程でのゆっくりとした焼結に
よる脱水効果をスート体全体にわたってほぼ均一に進行
させることができ、透明ガラス化後の合成石英ガラス中
のＯＨ基濃度を所望の分布を有するように設定すること
ができる。Therefore, in the preliminary calcination step, the density of the soot body is made uniform by performing an operation of rapidly increasing the density of the least dense portion around the soot body as compared with the other portions, that is, baking. Turn into By this preliminary calcination, the dehydration effect due to slow sintering in the calcination step, which is the next step, can be made to proceed almost uniformly over the entire soot body, and the OH group concentration in the synthetic quartz glass after transparent vitrification Can be set to have a desired distribution.
【００２１】この際の加熱は、約１．５〜５０パスカル
の圧力下、約１３００〜１４００℃で１〜５時間と、後
で行う仮焼よりも若干高い温度で短時間行うのが好まし
い。前記事前仮焼の温度が約１３００℃未満であると、
前記事前仮焼による焼きしめ効果が少なく、他方約１３
００℃と低温でも加熱時間が５時間を超えるとスート体
の密度の低い周辺部分のみならず、スート体全体がゆっ
くりと焼きしまり、目的とするスート体密度の均一化が
進みにくい傾向が表われる。前記事前仮焼の温度が約１
４００℃を超えると、急激に空隙の収縮が進行し、なか
でもスート体周辺部分の焼きしめが急激に進行するた
め、その表層部分が透明ガラス化し、その後の仮焼、透
明化工程により十分な脱水効果が得られず所望の合成石
英ガラスを得ることができない。他方１４００℃と高い
温度でも、加熱時間を１時間未満とすると、焼きしめ効
果が得られず、スート体の密度を均一化することができ
ない。The heating at this time is preferably carried out at a pressure of about 1.5 to 50 Pascal at about 1300 to 1400 ° C. for 1 to 5 hours and at a temperature slightly higher than that of the calcination performed later for a short time. When the temperature of the pre-calcination is less than about 1300 ° C.,
The pre-calcination has little effect on baking, while about 13
Even at a low temperature of 00 ° C., if the heating time exceeds 5 hours, not only the peripheral portion of the soot body having a low density but also the entire soot body is slowly burned, and it tends to be difficult to make the target soot body density uniform. . The pre-calcination temperature is about 1
When it exceeds 400 ° C, the shrinkage of the voids rapidly progresses, and in particular, the soaking around the soot body rapidly progresses, so that the surface layer portion becomes transparent glass, and the subsequent calcination and clarification steps are sufficient. The dehydration effect cannot be obtained and the desired synthetic quartz glass cannot be obtained. On the other hand, even at a high temperature of 1400 ° C., if the heating time is less than 1 hour, the baking effect cannot be obtained and the density of the soot body cannot be made uniform.
【００２２】前記事前仮焼の際の圧力が約１．５パスカ
ルよりも小さいと、加熱の際に酸素が石英ガラスより抜
け易くなり、これにより酸素欠乏欠陥が生じて紫外及び
真空紫外光の透過率低下の原因となり易く、他方前記事
前仮焼の際の圧力が約５０パスカルを超えると、スート
体の焼きしめ効果が少なく、スート体の密度を均一化す
ることが難しい。If the pressure during the pre-calcination is less than about 1.5 Pascal, oxygen is more likely to escape from the quartz glass during heating, which causes oxygen deficiency defects to cause ultraviolet and vacuum ultraviolet light. On the other hand, when the pressure during the pre-calcination exceeds about 50 Pascal, the soot body is less likely to be baked and it is difficult to make the density of the soot body uniform.
【００２３】この後、仮焼処理を同じ真空条件下、約１
２００〜１３００℃で約１０〜４０時間行い、スート体
中の石英ガラス微粒子中に一部含まれるＳｉ−ＯＨをＳ
ｉ−Ｏ−Ｓｉに変化させたり付着水を気化脱気せしめ、
その際に生じる水分を除去脱水する。また、この仮焼処
理によりスート体中のＯＨ基濃度の分布を調整する。前
記仮焼の温度が約１２００℃未満であると、水分の除去
がゆっくりとしか進行せず、ＯＨ基濃度が十分に低下せ
ず、またその濃度分布の調整もうまく行かない。他方、
前記仮焼の温度が１３００℃を超えると、内部から十分
に水分が除去されないうちに緻密化してしまい、やはり
高濃度のＯＨ基が残留することになる。Thereafter, the calcination process is performed under the same vacuum condition for about 1 minute.
It is performed at 200 to 1300 ° C. for about 10 to 40 hours, and Si—OH partially contained in the silica glass fine particles in the soot body is converted into S.
Change to i-O-Si or vaporize and deaerate the attached water,
The water generated at that time is removed and dehydrated. Moreover, the distribution of the OH group concentration in the soot body is adjusted by this calcination process. If the calcination temperature is lower than about 1200 ° C., the removal of water proceeds only slowly, the OH group concentration does not decrease sufficiently, and the concentration distribution cannot be adjusted well. On the other hand,
If the calcination temperature exceeds 1300 ° C., densification occurs before water is sufficiently removed from the inside, and a high concentration of OH groups remains.
【００２４】この仮焼により、中央部分に近づくに従っ
てＯＨ基濃度が高く、中央部分にＯＨ濃度の極大値とな
る部分が存在し、逆に周辺部分にいくに従ってその濃度
が低下するＯＨ基濃度の分布が形成される。By this calcination, the OH group concentration becomes higher as it approaches the central portion, and there is a portion where the OH concentration has a maximum value in the central portion, and conversely, the concentration decreases as it goes to the peripheral portion. A distribution is formed.
【００２５】次に、同じ真空条件下、仮焼後の石英ガラ
スを加熱して０．５〜５℃／分の条件で昇温させ、通常
行われている条件、すなわち約１４２０〜１６００℃の
温度範囲で３〜８時間透明化処理を行う。前記透明化の
温度が約１４２０℃未満では、緻密化が進行しにくく生
産性が悪くなり、他方前記透明化の温度が約１６００℃
を超えると電力の消費によりコスト増加となる。Next, under the same vacuum conditions, the quartz glass after calcination is heated to raise the temperature at 0.5 to 5 ° C./min, and the conditions usually used, that is, about 1420 to 1600 ° C. Clarification treatment is performed within a temperature range for 3 to 8 hours. If the temperature of the clarification is less than about 1420 ° C., the densification is difficult to proceed and the productivity is deteriorated.
If it exceeds, the cost will increase due to power consumption.
【００２６】前記工程の後、約０．５〜５℃／分の条件
下で徐冷することにより、透明化された合成石英ガラス
母材が製造される。After the above steps, a transparent synthetic quartz glass base material is manufactured by gradually cooling under the condition of about 0.5 to 5 ° C./min.
【００２７】前記方法により製造された合成石英ガラス
母材は、金属不純物等の含有量が極めて少ないため、通
常の石英ガラス材として使用することも可能である。し
かし、前記ＯＨ基濃度の分布をコントロールすることに
より、屈折率に分布が形成されているので、光学的な用
途に使用しようとすれば、この合成石英ガラス母材に以
下に説明するような仮想温度分布を形成するのが好まし
く、これにより全体が均一な屈折率を有する合成石英ガ
ラス材を製造することができる。Since the synthetic quartz glass base material produced by the above method has a very small content of metal impurities and the like, it can be used as an ordinary quartz glass material. However, since the distribution of the refractive index is formed by controlling the distribution of the OH group concentration, if the synthetic quartz glass base material is assumed to have the virtual It is preferable to form a temperature distribution, which makes it possible to produce a synthetic quartz glass material having a uniform refractive index throughout.
【００２８】この場合、初めに前記合成石英ガラス母材
を下記の条件で加熱成形し徐冷した後、切削加工等を行
って所定の大きさにし、製品を製造する。勿論、得られ
た合成石英ガラス母材を冷却せず、同様の条件で処理を
行うことも可能である。In this case, first, the synthetic quartz glass base material is heat-molded under the following conditions, gradually cooled, and then cut to a predetermined size to manufacture a product. Of course, it is also possible to perform the treatment under the same conditions without cooling the obtained synthetic quartz glass base material.
【００２９】成形の際には、前記母材を約１６００〜２
０００℃の温度まで加熱し、例えば高純度カーボン等か
らなる型を用いてプレスすることにより大型のレンズ、
ミラー、窓部材等の光学部材の形状を有するものに成形
する。この成形された光学用合成石英ガラスを一旦、５
〜３０℃／分の条件で約１５００〜１６００℃まで冷却
し、この温度範囲で０〜１０時間保持する均温化処理を
行う。ここで、０時間の場合は厳密には均温化処理を行
っておらず、この温度で冷却速度を切り替えるのみであ
るが、ここでは０時間の場合も含めて均温化処理という
ことにする。At the time of molding, about 1600 to 2 of the above base material is used.
By heating to a temperature of 000 ° C and pressing with a mold made of, for example, high-purity carbon, a large lens,
It is molded into the shape of an optical member such as a mirror or a window member. Once the molded synthetic quartz glass for optics is
The temperature is cooled to about 1500 to 1600 ° C. under the condition of -30 ° C./min, and the temperature is kept in this temperature range for 0 to 10 hours to perform a soaking treatment. Here, in the case of 0 hour, the temperature equalizing process is not strictly performed, and only the cooling rate is switched at this temperature, but here, the case of 0 hour is also referred to as the temperature equalizing process. .
【００３０】この均温化処理の温度が約１５００℃未満
であると、徐冷する前の温度が低過ぎるため、以下に述
べるような状態の仮想温度分布を形成するのが難しくな
る。If the temperature of the soaking treatment is less than about 1500 ° C., the temperature before the slow cooling is too low, so that it becomes difficult to form a virtual temperature distribution in the state described below.
【００３１】前記均温化処理の後、少なくとも１５００
℃以上の温度から、５℃／分未満、好ましくは０．１〜
４℃／分未満の温度で冷却することにより合成石英ガラ
ス材の仮想温度分布を形成する。After the soaking treatment, at least 1500
From a temperature of ℃ or more to less than 5 ℃ / min, preferably 0.1
A virtual temperature distribution of the synthetic quartz glass material is formed by cooling at a temperature of less than 4 ° C / min.
【００３２】室温における石英ガラスの密度、屈折率等
の特性は、そのガラスが過去の製造過程における高温度
域及び前記高温度域から室温までの冷却過程での熱履歴
を反映したものであり、仮想温度（Fictive Temperatu
re）とは、そのガラスが過去の熱履歴のなかで、なじま
されたときの温度、すなわち上記特性値が決定されたと
きの温度をいう(R.Bruckner,J.Non-Crystaline Solids,
5,1970, pp.133-134)。この仮想温度の概念は、石英ガ
ラスのみならず、ガラス全般に当てはまる概念であり、
もう少し簡略にいうならば、室温のガラス密度、屈折率
等の特性値がその仮想温度（室温よりも高温度）のガラ
スの平衡状態の特性値になっていることを意味する。The characteristics such as the density and the refractive index of the quartz glass at room temperature reflect the thermal history of the glass in the high temperature range in the past manufacturing process and the cooling process from the high temperature range to room temperature. Fictive Temperatu
re) is the temperature at which the glass has been acclimated in the past thermal history, that is, the temperature at which the above characteristic values are determined (R. Bruckner, J. Non-Crystaline Solids,
5, 1970, pp.133-134). This virtual temperature concept applies not only to quartz glass, but to all glass,
To be a little simpler, it means that the characteristic values such as the glass density and the refractive index at room temperature are the characteristic values of the glass in the equilibrium state at the fictive temperature (higher than room temperature).
【００３３】図１は前記公報に記載された石英ガラスの
温度と密度との関係、及び冷却の際の密度の変化の様子
を示したグラフであり、ｇs 、ｇt で示した温度ｔは、
それぞれゆっくりとした冷却の場合のガラス転移温度及
び早い冷却の場合のガラス転移温度を示している。[0033] Figure 1 is a graph relationship, and showing how the change in density upon cooling the temperature and density of the quartz glass described in the publication, g s, the temperature t indicated by g t is ,
The glass transition temperature in the case of slow cooling and the glass transition temperature in the case of fast cooling are shown respectively.
【００３４】前述のR.Brucknerによると、第１図に示す
ように、石英ガラスは約１５００℃において密度が最小
になり、１５００℃より高い温度から冷却する場合と、
１５００℃より低い温度から冷却する場合とで、石英ガ
ラス中の密度の分布状態が異なることが知られている。
すなわち、１５００℃より低い温度から冷却する場合に
は、周囲が早く冷却されるために内部に比べて周囲がよ
り密度が大きくなり、他方１５００℃よりも高い温度か
ら冷却する場合には、周囲が内部に比べて早く冷却され
ることは上記の場合と同様であるが、密度は内部に比べ
て周囲の方が小さくなる。密度と相関関係を有する仮想
温度も、前記密度と同様の分布を生じ、仮想温度を測定
することにより前記仮想温度に起因する屈折率分布を特
定することが可能になるが、本発明の場合のように、約
１５００℃より高い温度から冷却すると、内部の仮想温
度分布の方が周囲の仮想温度分布より低い状態となり、
内部の密度の方が周囲の密度より大きい状態、すなわち
内部の方が周囲より屈折率の高い分布が生じ、ＯＨ基濃
度分布により生じる屈折率分布と逆になるため、お互い
の屈折率の変動を打ち消し合い、極めて均一な屈折率分
布を形成することができる。According to the above-mentioned R. Bruckner, as shown in FIG. 1, the quartz glass has the minimum density at about 1500 ° C., and is cooled from a temperature higher than 1500 ° C.
It is known that the distribution state of the density in the quartz glass is different when cooling from a temperature lower than 1500 ° C.
That is, when cooling from a temperature lower than 1500 ° C., the surroundings are cooled faster, so that the surroundings have a higher density than the inside, and when cooling from a temperature higher than 1500 ° C., the surroundings are cooled. It is similar to the above case that it is cooled faster than the inside, but the density is smaller in the surroundings than in the inside. The fictive temperature having a correlation with the density also produces the same distribution as the density, and by measuring the fictive temperature, it becomes possible to specify the refractive index distribution due to the fictive temperature, but in the case of the present invention, Thus, when cooling from a temperature higher than about 1500 ° C., the internal virtual temperature distribution becomes lower than the surrounding virtual temperature distribution,
When the internal density is higher than the surrounding density, that is, the inside has a distribution with a higher refractive index than the surroundings, which is the opposite of the refractive index distribution caused by the OH group concentration distribution. It is possible to cancel each other to form a very uniform refractive index distribution.
【００３５】次に、このようにして製造された光学用合
成石英ガラス材を１×１０3 〜１×１０6 Ｐａの水素ガ
ス雰囲気下、６１０〜７９０℃で加熱することにより水
素をドープする。Next, the synthetic quartz glass material for optics manufactured as described above is doped with hydrogen by heating at 610 to 790 ° C. in a hydrogen gas atmosphere of 1 × 10 3 to 1 × 10 6 Pa.
【００３６】水素ガス雰囲気が１×１０6 Ｐａを超える
と水素ドープの速度が早過ぎてドープ量の制御が難しく
なり、他方水素ガス雰囲気が１×１０3 Ｐａ未満では溶
存させる水素ガスの揮発が促進され、ドープが困難とな
る。When the hydrogen gas atmosphere exceeds 1 × 10 6 Pa, the hydrogen doping rate becomes too fast and the control of the doping amount becomes difficult. On the other hand, when the hydrogen gas atmosphere is less than 1 × 10 3 Pa, the dissolved hydrogen gas is volatilized. It is accelerated, and doping becomes difficult.
【００３７】また、加熱温度が７９０℃を超えるとドー
プした水素のうち、（原子状水素／分子状水素）の比が
大きくなり、レーザー耐光性の向上に効果的な分子状水
素のドープ量が不足し、他方加熱温度が６１０℃未満で
あるとドープ速度が遅過ぎ、ドープ時間が長くかかりす
ぎる。なお、６１０〜７９０℃の温度範囲での加熱は比
較的低温であるため、前工程で生じた石英ガラス中の仮
想温度分布を変えるものではない。If the heating temperature exceeds 790 ° C., the ratio of (atomic hydrogen / molecular hydrogen) in the doped hydrogen becomes large, and the doping amount of molecular hydrogen effective for improving laser light resistance is increased. If the heating temperature is lower than 610 ° C., the doping rate will be too slow and the doping time will be too long. Since heating in the temperature range of 610 to 790 ° C is relatively low, it does not change the fictive temperature distribution in the quartz glass generated in the previous step.
【００３８】前記した合成石英ガラス材又は光学用合成
石英ガラス製品（以下、両者を含めて合成石英ガラス材
とも記す）の製造工程により、ＯＨ基濃度の分布に基づ
く屈折率分布を打ち消すように、仮想温度分布に起因す
る屈折率分布を形成することができ、屈折率の変動幅が
極めて小さく、かつレーザー照射によっても真空紫外光
〜紫外光の透過率が低下しない合成石英ガラス材を製造
することが可能となる。By the manufacturing process of the above-mentioned synthetic quartz glass material or optical synthetic quartz glass product (hereinafter, both are also referred to as synthetic quartz glass material), the refractive index distribution based on the distribution of the OH group concentration is canceled. To produce a synthetic quartz glass material that can form a refractive index distribution due to a virtual temperature distribution, has a very small fluctuation range of the refractive index, and does not reduce the transmittance of vacuum ultraviolet light to ultraviolet light even by laser irradiation. Is possible.
【００３９】前記工程により製造された合成石英ガラス
材中のＯＨ基濃度の最大値は、約６０ｐｐｍ程度以下で
あることが好ましく、２０〜４５ｐｐｍ程度がより好ま
しい。また、ＯＨ基濃度の最大値と最小値との差は４５
ｐｐｍ以下であることが好ましく、３０ｐｐｍ以下であ
ることがより好ましい。The maximum value of the OH group concentration in the synthetic quartz glass material produced by the above process is preferably about 60 ppm or less, more preferably about 20 to 45 ppm. Further, the difference between the maximum value and the minimum value of the OH group concentration is 45
It is preferably ppm or less, and more preferably 30 ppm or less.
【００４０】ＯＨ基の濃度の最大値と最小値との差が約
４５ｐｐｍのとき、屈折率の変動幅（Δｎ）は約４．５
×１０-6となり、これより大きい場合には、前記ＯＨ基
濃度の分布に基づく屈折率の変動分布を、仮想温度分布
を調節することにより打ち消すのが困難になる。When the difference between the maximum value and the minimum value of the OH group concentration is about 45 ppm, the fluctuation range (Δn) of the refractive index is about 4.5.
× 10 -6 next, if larger than this, the variation distribution of the refractive index based on the distribution of the OH group concentration, it becomes difficult to cancel by adjusting the fictive temperature distribution.
【００４１】このようにして得られた光学用合成石英ガ
ラス材は、均質性に優れ、屈折率の変動幅（Δｎ）が極
めて小さい。前記屈折率の変動幅（Δｎ）は、そのサイ
ズにより異なるが、例えば直径が約２００〜３００ｍｍ
で、長さが約６０〜１５０ｍｍとサイズの大きいものに
おいても、その屈折率の変動幅（Δｎ）が約１×１０-6
未満と小さい。前記サイズよりも小さなものにおいて
は、当然、屈折率の変動幅は約１×１０-6未満と小さ
く、その複屈折率も約３ｎｍ／ｃｍ以下となる。The optical synthetic quartz glass material thus obtained is excellent in homogeneity and has a very small fluctuation range (Δn) in the refractive index. The fluctuation range (Δn) of the refractive index varies depending on the size, but the diameter is, for example, about 200 to 300 mm.
Even in a large size having a length of about 60 to 150 mm, the fluctuation range (Δn) of the refractive index is about 1 × 10 −6.
Less than and less than. When the size is smaller than the above size, the fluctuation range of the refractive index is naturally as small as less than about 1 × 10 −6 , and the birefringence thereof is about 3 nm / cm or less.
【００４２】また、前記光学用合成石英ガラス材はこの
ような均質性を有することから、少なくとも一方向脈理
フリーであり、製造条件によっては三方向脈理フリーと
極めて均質性に優れたものとなる。Further, since the synthetic quartz glass material for optics has such homogeneity, it is free of striae in at least one direction and, depending on manufacturing conditions, is free of striae in three directions and is extremely excellent in homogeneity. Become.
【００４３】本発明に係る合成石英ガラス材は、得られ
たスートを、事前仮焼、仮焼、昇温、透明化の工程を経
て透明化しており、このような連続的な処理により前記
ＯＨ基濃度の分布は変曲点を有さない。In the synthetic quartz glass material according to the present invention, the soot obtained is made transparent through the steps of preliminary calcination, calcination, temperature increase and clarification. The distribution of base concentration has no inflection point.
【００４４】塩素の濃度についても、スート体形成後の
加熱処理によってかなりの程度除去することが可能であ
り、最終的な合成石英ガラス材の濃度は１０ｐｐｍ以下
であることが好ましく、１ｐｐｍ以下であることがより
好ましい。また、塩素濃度の最大値と最小値との差は１
ｐｐｍ以下であることが好ましい。塩素濃度が１０ｐｐ
ｍを超えると、塩素濃度の最大値と最小値との差を１ｐ
ｐｍ以下に保つのが難しくなる場合がある。また、塩素
濃度の最大値と最小値との差が１ｐｐｍを超えると、前
記塩素濃度の不均一性が屈折率に影響し、屈折率を小さ
く保つことが難しくなる。Regarding the concentration of chlorine, it is possible to remove it to a large extent by the heat treatment after the soot body is formed, and the final concentration of the synthetic quartz glass material is preferably 10 ppm or less, preferably 1 ppm or less. Is more preferable. The difference between the maximum and minimum chlorine concentration is 1
It is preferably at most ppm. Chlorine concentration is 10pp
When it exceeds m, the difference between the maximum and minimum chlorine concentration is 1p.
It can be difficult to keep below pm. If the difference between the maximum and minimum chlorine concentrations exceeds 1 ppm, the nonuniform chlorine concentration affects the refractive index, making it difficult to keep the refractive index small.
【００４５】金属不純物については、原料中の金属不純
物の含有量に大きく左右され、製造方法自体には余り左
右されない。従って、いずれの製造方法においても、合
成石英ガラス材中の金属不純物の総含有量が０．１５ｐ
ｐｍ以下であり、Ａｌの含有量が０．０１ｐｐｍ以下、
Ｎａ、Ｋ、及びＬｉの各含有量が０．０２ｐｐｍ以下、
Ｃａ、Ｆｅ、Ｔｉ、Ｃｒ、Ｎｉ、Ｐ、Ｂ、Ｍｇ、Ｃｕ、
Ｚｒ、及びＺｎの各含有量が０．００８ｐｐｍ以下であ
ることが好ましい。Regarding the metal impurities, it largely depends on the content of the metal impurities in the raw material, and not much on the manufacturing method itself. Therefore, in any of the manufacturing methods, the total content of metal impurities in the synthetic quartz glass material is 0.15 p.
pm or less, the content of Al is 0.01 ppm or less,
Each content of Na, K, and Li is 0.02 ppm or less,
Ca, Fe, Ti, Cr, Ni, P, B, Mg, Cu,
The Zr and Zn contents are preferably 0.008 ppm or less.
【００４６】また、前記光学用合成石英ガラス材中に
は、後述するようにレーザー光照射時にガラス構造の欠
陥を生じることによる、光吸収、蛍光発光等の問題発生
を防止するために、水素が５×１０15〜１×１０19ｍｏ
ｌ／ｃｍ3 含まれている。本願発明者が先に出願した特
願平６−２１６２３３号の明細書に記載しているよう
に、高エネルギー密度のレーザー光の照射により合成石
英ガラス中に、≡Ｓｉ−Ｏ°（非結合酸素）欠陥や≡Ｓ
ｉ・（Ｅ’中心）欠陥等の欠陥が生成され易くなるが、
合成石英ガラス中に水素（Ｈ2 分子あるいはＨ原子）、
特に分子状水素（Ｈ2 分子）が適量溶存すると、レーザ
ー光照射時に上記欠陥のうち、特に非酸素結合欠陥を抑
制することができる。その好ましいＨ2 分子含有量１０
15〜１０18個／ｃｍ3 程度を得るためには、水素の含有
量は５×１０15〜１×１０19ｍｏｌ／ｃｍ3 程度が必要
となる。Further, in the synthetic quartz glass material for optics, hydrogen is contained in order to prevent problems such as light absorption and fluorescence emission due to defects in the glass structure upon irradiation with laser light as described later. 5 x 10 15 to 1 x 10 19 mo
1 / cm 3 is included. As described in the specification of Japanese Patent Application No. 6-216233 previously filed by the inventor of the present application, ≡Si-O ° (non-bonded oxygen) is formed in synthetic quartz glass by irradiation with a laser beam having a high energy density. ) Defects and ≡S
Defects such as i · (E ′ center) defects are easily generated,
Hydrogen (H 2 molecule or H atom) in synthetic quartz glass,
Particularly, when a proper amount of molecular hydrogen (H 2 molecule) is dissolved, among the above defects, particularly non-oxygen bond defects can be suppressed during laser light irradiation. Its preferable H 2 molecule content is 10
In order to obtain about 15 to 10 18 pieces / cm 3 , the hydrogen content needs to be about 5 × 10 15 to 1 × 10 19 mol / cm 3 .
【００４７】前記水素の含有量が５×１０15ｍｏｌ／ｃ
ｍ3 未満であると、レーザー光等を照射した際に欠陥等
が生成し易く、透過率の低下が大きくなる傾向が表わ
れ、他方前記水素の含有量が１×１０19ｍｏｌ／ｃｍ3
を超えると、原子状水素（Ｈ原子）の含有量が増加し、
レーザー光照射時に下記の化１式の反応が進行してＥ’
中心欠陥が生成し易くなる。前記非結合酸素欠陥は、上
記のような条件で合成石英ガラス材を製造することによ
り、最小限の濃度に止めることができる。The hydrogen content is 5 × 10 15 mol / c
When it is less than m 3 , defects and the like are likely to be generated when irradiated with laser light and the like, and the transmittance is likely to be lowered, while the hydrogen content is 1 × 10 19 mol / cm 3.
When it exceeds, the content of atomic hydrogen (H atom) increases,
Upon irradiation with laser light, the reaction of the following chemical formula 1 proceeds and E ′
A central defect is easily generated. The non-bonded oxygen defects can be suppressed to the minimum concentration by producing the synthetic quartz glass material under the above conditions.
【００４８】[0048]
【化１】≡Ｓｉ−Ｈ → ≡Ｓｉ・（Ｅ’中心）＋Ｈ・[Chemical formula 1] ≡Si-H → ≡Si · (E ′ center) + H ·
【００４９】[0049]
【作用】本発明に係る合成石英ガラス母材の製造方法に
よれば、気相軸付け法により形成された多孔質合成石英
ガラスに、事前仮焼工程として、１．５〜５０パスカル
の圧力下、１３００〜１４００℃で１〜５時間の加熱処
理を施して密度を均質化し、次に仮焼工程として、同じ
圧力下、１２００〜１４００℃の温度で１０〜４０時間
加熱して水分等を除去した後、０．５〜５℃／分の速度
で昇温し、さらに透明化工程を行い透明ガラス化するの
で、前記合成石英ガラス母材中に塩素や金属等の不純物
含有量が極めて少なく、中央部分に極大となる領域が存
在し、該領域を中心に周辺部分にいくに従って次第に低
下するＯＨ基濃度の分布が形成される。According to the method for producing a synthetic quartz glass preform according to the present invention, a porous synthetic quartz glass formed by a vapor-phase axial method is preliminarily calcined under a pressure of 1.5 to 50 Pascals. , Heat treatment at 1300 to 1400 ° C for 1 to 5 hours to homogenize the density, and then as a calcination step, remove water and the like by heating at a temperature of 1200 to 1400 ° C for 10 to 40 hours under the same pressure. After that, the temperature is raised at a rate of 0.5 to 5 ° C./minute, and a transparentizing step is further performed to form a transparent glass, so that the content of impurities such as chlorine and metal in the synthetic quartz glass base material is extremely small, There is a maximum area in the central part, and a distribution of the OH group concentration is formed which gradually decreases toward the peripheral part with the area as the center.
【００５０】この合成石英ガラス母材を使用して１５０
０〜２０００℃の温度に加熱した後、少なくとも１５０
０℃以上の温度から室温まで５℃／分以下の速度で徐冷
し、前記ＯＨ基濃度の分布に基づく屈折率分布を打ち消
すように、仮想温度分布を形成することにより、極めて
均一な屈折率を有する合成石英ガラス材を製造すること
ができる。Using this synthetic quartz glass base material, 150
After heating to a temperature of 0 to 2000 ° C., at least 150
By gradually cooling from a temperature of 0 ° C. or higher to room temperature at a rate of 5 ° C./min or less, and forming a virtual temperature distribution so as to cancel the refractive index distribution based on the distribution of the OH group concentration, an extremely uniform refractive index is obtained. It is possible to manufacture a synthetic quartz glass material having
【００５１】[0051]
【実施例及び比較例】以下、本発明の実施例に係る合成
石英ガラス材及びその製造方法を説明する。EXAMPLES AND COMPARATIVE EXAMPLES Synthetic quartz glass materials according to the examples of the present invention and methods for producing the same will be described below.
【００５２】［実施例１〜１３及び比較例１〜１４］Ｖ
ＡＤ法により多孔質合成石英ガラス（スート体）を合成
した。[Examples 1 to 13 and Comparative Examples 1 to 14] V
Porous synthetic quartz glass (soot body) was synthesized by the AD method.
【００５３】高純度ケイ素化合物である四塩化ケイ素
（ＳｉＣｌ4 ）を原料とし、酸素−水素火炎中で気相化
学反応により石英ガラス微粒子を合成するとともにこれ
を種棒の周囲に付着、堆積させ、多孔質合成石英ガラス
（スート体）を合成した。Using silicon tetrachloride (SiCl 4 ) which is a high-purity silicon compound as a raw material, quartz glass fine particles were synthesized by a gas phase chemical reaction in an oxygen-hydrogen flame, and the fine quartz glass particles were adhered and deposited around the seed rod. Porous synthetic quartz glass (soot body) was synthesized.
【００５４】次に、この合成された多孔質合成石英ガラ
スを下記の表１に示した条件で事前仮焼、仮焼、昇温、
透明化、及び冷却を行い、下記の表３に示した寸法の合
成石英ガラス母材を製造した。この合成石英ガラス母材
の特性を同じく下記の表３に示している。Next, the synthesized porous synthetic quartz glass was pre-calcined, calcined, and heated under the conditions shown in Table 1 below.
It was made transparent and cooled to manufacture a synthetic quartz glass base material having the dimensions shown in Table 3 below. The characteristics of this synthetic quartz glass base material are also shown in Table 3 below.
【００５５】次に、前記工程で製造された合成石英ガラ
ス母材の切削、加工等を行い、得られた部材を用いて、
表１に示した加熱成形条件で、加熱、成形、均温化処理
を行った。その後、表１に示した速度で冷却することに
より仮想温度分布を形成した。次に、前記仮想温度分布
が形成された合成石英ガラス材を用い、表１に示した条
件で水素ガス処理を行い、前記合成石英ガラス材に水素
をドープさせた。得られた光学用合成石英ガラス製品の
特性を下記の表５に示している。Next, the synthetic quartz glass base material manufactured in the above process is cut and processed, and the obtained member is used.
Under the heat molding conditions shown in Table 1, heating, molding and soaking treatment were performed. Then, by cooling at the rate shown in Table 1, a virtual temperature distribution was formed. Next, using the synthetic quartz glass material with the virtual temperature distribution formed, hydrogen gas treatment was performed under the conditions shown in Table 1 to dope the synthetic quartz glass material with hydrogen. The characteristics of the obtained synthetic quartz glass product for optics are shown in Table 5 below.
【００５６】また、屈折率変動幅（Δｎ）が実施例に係
る合成石英ガラス材に比べて大きい、比較例に係る合成
石英ガラス材についても、合成石英ガラス材の製造条
件、加熱成形条件及び水素ドープ条件を下記の表２に、
合成石英ガラス母材の特性を表４に、合成石英ガラス製
品の特性を下記の表６に示している。Further, regarding the synthetic quartz glass material according to the comparative example, in which the fluctuation range (Δn) of the refractive index is larger than that of the synthetic quartz glass material according to the example, the synthetic quartz glass material manufacturing conditions, heat molding conditions and hydrogen The doping conditions are shown in Table 2 below.
The characteristics of the synthetic quartz glass base material are shown in Table 4, and the characteristics of the synthetic quartz glass product are shown in Table 6 below.
【００５７】なお、仮想温度については、K.M.Davis ら
が提案した赤外線分光光度計を用いた方法（K.M.Davis
and M.Tomozawa ニューガラスフォーラム 平成５年度
第４回シリカガラス研究会 ２１５〜２５５頁 １９９
４年１月１７日）により測定し、屈折率変動幅（Δｎ）
については、Ｚｙｇｏ社製のフィゾー型干渉計（Ｍａｒ
ｋ−ＩＶ）により測定し、複屈折率については、オーク
製作所社製の高感度複屈折率測定装置（ＡＤＲ−３０
０）により測定した。また、水素ガス放出量について
は、森本らが提案した放出ガス量を質量分析する方法
（森本幸裕他 照明学会 東京支部大会誌 １６〜２５
頁 １９８９年）及びレーザーラマン散乱測定法により
測定した。Regarding the fictive temperature, a method using an infrared spectrophotometer proposed by KMDavis et al. (KMDavis
and M. Tomozawa New Glass Forum 1993 4th Silica Glass Research Group 215-255 199
Refractive index fluctuation range (Δn)
For the Fyzo interferometer (Mar
k-IV), and the birefringence is measured with a high-sensitivity birefringence measuring device (ADR-30 manufactured by Oak Manufacturing Co., Ltd.).
0). Regarding the amount of hydrogen gas released, a method proposed by Morimoto et al. For mass spectrometry of the amount of released gas (Yukihiro Morimoto et al., Lighting Society Tokyo Section Conference 16-25)
Page 1989) and laser Raman scattering measurement method.
【００５８】図２は実施例及び比較例に係る合成石英ガ
ラス母材の製造方法で、所定の工程の終了後における合
成石英ガラスの密度分布を示したグラフである。図２に
おいて、実線は実施例１の場合の密度分布を示したもの
であり、が熱処理前の多孔質合成石英ガラス（スート
体）、が事前仮焼処理後の多孔質合成石英ガラス（事
前仮焼後スート体）、が仮焼処理後の合成石英ガラス
体を示しており、における点線は事前仮焼を行わない
場合（比較例１）の合成石英ガラス体を示している。FIG. 2 is a graph showing the density distribution of the synthetic quartz glass after the completion of the predetermined steps in the synthetic quartz glass base material manufacturing method according to the example and the comparative example. In FIG. 2, the solid line shows the density distribution in the case of Example 1, where is the porous synthetic quartz glass before heat treatment (soot body), is the porous synthetic quartz glass after pre-calcination treatment (pre-temporary Shows the synthetic quartz glass body after the calcination treatment, and the dotted line in the figure shows the synthetic quartz glass body in the case where the preliminary calcination is not performed (Comparative Example 1).
【００５９】[0059]
【表１】 [Table 1]
【００６０】[0060]
【表２】 [Table 2]
【００６１】[0061]
【表３】 [Table 3]
【００６２】[0062]
【表４】 [Table 4]
【００６３】[0063]
【表５】 [Table 5]
【００６４】[0064]
【表６】 [Table 6]
【００６５】上記の表３及び表５に示した結果より明ら
かなように、実施例に係る光学用合成石英ガラス母材及
び光学用合成石英ガラス製品の中央部分にＯＨ基濃度の
極大となる領域が存在し、該領域を中心に周辺部分にい
くに従ってＯＨ基濃度が次第に低下し、壁面部分で濃度
の最小値となる濃度分布が存在しており、このＯＨ基濃
度分布に基づく屈折率分布を打ち消すように、仮想温度
分布に起因する屈折率分布が形成されているので、前記
合成石英ガラス材内部全体の屈折率が極めて均一（屈折
率変動幅Δｎ≦０．９×１０-6）になる。また、塩素の
濃度は１ｐｐｍ未満であり、複屈折率も３ｎｍ／ｃｍ以
下と極めて小さく、脈理も三方向フリーと均質性に優れ
た材料となっている。さらに、表には示していないが実
施例に係る光学用合成石英ガラス製品の金属不純物含有
量はトータル量として、０．１５ｐｐｍ未満であり、各
金属不純物含有量は、Ａｌの含有量が０．０１ｐｐｍ以
下、Ｎａ、Ｋ、及びＬｉの各含有量が０．０２ｐｐｍ以
下、Ｃａ、Ｆｅ、Ｔｉ、Ｃｒ、Ｎｉ、Ｐ、Ｂ、Ｍｇ、Ｃ
ｕ、Ｚｒ、及びＺｎの各含有量が０．００８ｐｐｍ以下
であった。この光学用合成石英ガラス製品中の不純物濃
度はプラズマ発光（ＩＣＰ）分析法及び放射化分析法に
より測定した。As is clear from the results shown in Tables 3 and 5, the region where the OH group concentration is maximum in the central portion of the optical synthetic quartz glass base material and the optical synthetic quartz glass product according to the examples. Exists, and the OH group concentration gradually decreases toward the peripheral part around this region, and there is a concentration distribution with the minimum value of the concentration on the wall surface part, and the refractive index distribution based on this OH group concentration distribution is Since the refractive index distribution due to the virtual temperature distribution is formed so as to cancel out, the refractive index of the entire inside of the synthetic quartz glass material becomes extremely uniform (refractive index fluctuation width Δn ≦ 0.9 × 10 −6 ). . The chlorine concentration is less than 1 ppm, the birefringence is 3 nm / cm or less, which is extremely small, and the striae are three-direction free and are excellent in homogeneity. Further, although not shown in the table, the total amount of metal impurities of the optical synthetic quartz glass product according to the example is less than 0.15 ppm, and the content of each metal impurity is 0.1. 01ppm or less, each content of Na, K, and Li is 0.02ppm or less, Ca, Fe, Ti, Cr, Ni, P, B, Mg, C
Each content of u, Zr, and Zn was 0.008 ppm or less. The impurity concentration in this optical synthetic quartz glass product was measured by plasma emission (ICP) analysis and activation analysis.
【００６６】図２に示したように、実施例に係る製造方
法においては、事前仮焼工程によりほぼ全体にわたって
嵩密度が均一な多孔質体が得られたおり、仮焼によって
もその密度分布は変化していないため、ゆっくりと脱水
を行うことができ、ＯＨ基の濃度を低下させることがで
きるとともに、その濃度分布をコントロールすることが
可能となる。As shown in FIG. 2, in the manufacturing method according to the example, a porous body having a uniform bulk density was obtained almost entirely by the preliminary calcination step, and the density distribution was also obtained by calcination. Since there is no change, dehydration can be performed slowly, the concentration of OH groups can be reduced, and the concentration distribution can be controlled.
【００６７】また、実施例に係る光学用合成石英ガラス
材は、水素を５×１０15〜１×１０19ｍｏｌ／ｃｍ3 含
有しているため、対レーザー耐性に優れ、少なくともＫ
ｒＦ光レーザー（波長：２４８ｎｍ）を約４００ｍＪ／
ｃｍ2 の照射光エネルギー密度で１×１０6 ショット以
上照射しても２４８ｎｍも内部透過率が０．５％未満で
あった。Further, the optical synthetic quartz glass materials according to the examples contain hydrogen in an amount of 5 × 10 15 to 1 × 10 19 mol / cm 3, so that they are excellent in laser resistance and have at least K.
rF light laser (wavelength: 248 nm) about 400 mJ /
Even when irradiated with 1 × 10 6 shots or more at an irradiation light energy density of cm 2, the internal transmittance was less than 0.5% even at 248 nm.
【００６８】他方、比較例に係る光学用合成石英ガラス
製品においては、ＯＨ基の最大値と最小値との濃度差が
大きすぎるか、又はＯＨ基濃度分布により形成される屈
折率の変動分布と、形成された仮想温度分布による屈折
率変動分布が加算されたかたちになっているため、全体
の屈折率変動幅が実施例に係る光学用合成石英ガラス製
品の３倍を超えた値となっている。また、均温化の後の
冷却で、その速度が早すぎる場合には、複屈折率が１０
ｎｍ／ｃｍ以下と異方性が大きくなっている。さらに、
対レーザー耐性についても、ＫｒＦレーザーを約４００
ｍＪ／ｃｍ2 の照射光エネルギー密度で１×１０6 ショ
ット照射することにより、内部透過率が０．５％以上低
下してものが存在し、対レーザー耐性に劣る。On the other hand, in the optical synthetic quartz glass product according to the comparative example, the concentration difference between the maximum value and the minimum value of the OH group is too large, or the variation distribution of the refractive index formed by the OH group concentration distribution. Since the refractive index variation distribution due to the formed virtual temperature distribution is added, the entire refractive index variation range has a value that exceeds three times that of the optical synthetic quartz glass product according to the embodiment. There is. If the speed is too fast in cooling after soaking, the birefringence is 10
The anisotropy is as large as nm / cm or less. further,
As for the laser resistance, the KrF laser is about 400
By irradiating 1 × 10 6 shots with an irradiation light energy density of mJ / cm 2 , there are some whose internal transmittance is reduced by 0.5% or more, and the resistance to laser is poor.
【００６９】[0069]
【発明の効果】以上詳述したように本発明に係る合成石
英ガラス材にあっては、気相軸付け法により形成された
多孔質合成石英ガラスに、事前仮焼工程として、１．５
〜５０パスカルの圧力下、１３００〜１４００℃で１〜
５時間の加熱処理を施して密度を均質化し、次に仮焼工
程として、同じ圧力下、１２００〜１４００℃の温度で
１０〜４０時間加熱して水分等を除去した後、０．５〜
５℃／分の速度で昇温し、さらに透明化工程を行い透明
ガラス化するので、前記合成石英ガラス母材中に塩素や
金属等の不純物含有量が極めて少なく、中央部分に極大
値となる領域が存在し、該領域を中心に周辺部分にいく
に従って次第に低下するＯＨ基濃度分布を形成すること
ができる。As described above in detail, in the synthetic quartz glass material according to the present invention, the porous synthetic quartz glass formed by the vapor phase axial method has a pre-calcination step of 1.5.
1 to 1300 to 1400 ° C under pressure of -50 Pascal
After heat treatment for 5 hours to homogenize the density, and then as a calcination step, after heating at a temperature of 1200 to 1400 ° C. for 10 to 40 hours under the same pressure to remove water and the like, 0.5 to
Since the temperature is raised at a rate of 5 ° C./minute and a transparentizing step is performed to form a transparent vitreous material, the content of impurities such as chlorine and metal in the synthetic quartz glass base material is extremely small, and the central portion has a maximum value. It is possible to form an OH group concentration distribution in which a region exists and which gradually decreases toward the peripheral portion around the region.
【００７０】従って、この合成石英ガラス母材を使用し
て、１５００〜２０００℃の温度に加熱した後、前記加
熱温度より室温まで５℃／分以下の速度で徐冷し、前記
ＯＨ基濃度の分布に基づく屈折率分布を打ち消すよう
に、仮想温度分布を形成することにより、極めて均一な
屈折率を有する合成石英ガラス材を製造することができ
る。Therefore, using this synthetic quartz glass base material, after heating it to a temperature of 1500 to 2000 ° C., it is gradually cooled from the heating temperature to room temperature at a rate of 5 ° C./min or less to obtain the OH group concentration of By forming the virtual temperature distribution so as to cancel the refractive index distribution based on the distribution, it is possible to manufacture a synthetic quartz glass material having an extremely uniform refractive index.
【図１】石英ガラスの温度と密度との関係、及び冷却の
際の密度の変化の様子を示したグラフである。FIG. 1 is a graph showing the relationship between the temperature and the density of quartz glass and how the density changes during cooling.
【図２】実施例及び比較例に係る合成石英ガラス母材の
製造方法で、所定の工程の終了後における合成石英ガラ
スの密度分布を示したグラフである。FIG. 2 is a graph showing the density distribution of synthetic quartz glass after the completion of a predetermined process in the method for manufacturing a synthetic quartz glass base material according to Examples and Comparative Examples.
───────────────────────────────────────────────────── フロントページの続き (72)発明者 中村 哲之 兵庫県尼崎市東向島東之町１番地 住金石 英株式会社内 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tetsuyuki Nakamura 1 Higashiyuki-cho, Higashi-Mukojima, Amagasaki City, Hyogo Prefecture
Claims (1)
成石英ガラスに、事前仮焼工程として、１．５〜５０パ
スカルの圧力下、１３００〜１４００℃で１〜５時間の
加熱処理を施して密度を均質化し、次に仮焼工程とし
て、同じ圧力下、１２００〜１３００℃の温度で１０〜
４０時間加熱して水分等を除去した後、０．５〜５℃／
分の速度で昇温し、さらに透明化工程を行い透明ガラス
化することを特徴とする合成石英ガラス母材の製造方
法。1. A porous synthetic quartz glass formed by a vapor phase axial method is subjected to a heat treatment for 1 to 5 hours at 1300 to 1400 ° C. under a pressure of 1.5 to 50 Pascal as a preliminary calcination step. To homogenize the density, and then as a calcination step, under the same pressure, at a temperature of 1200 to 1300 ° C.
After heating for 40 hours to remove water and the like, 0.5 to 5 ° C /
A method for producing a synthetic quartz glass base material, which comprises raising the temperature at a rate of minutes, and further performing a transparentizing step to form a transparent vitreous material.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21084595A JP3274955B2 (en) | 1995-08-18 | 1995-08-18 | Method for producing synthetic quartz glass base material for optical components for use in ultraviolet region, and method for producing synthetic quartz glass material |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP21084595A JP3274955B2 (en) | 1995-08-18 | 1995-08-18 | Method for producing synthetic quartz glass base material for optical components for use in ultraviolet region, and method for producing synthetic quartz glass material |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0952719A true JPH0952719A (en) | 1997-02-25 |
| JP3274955B2 JP3274955B2 (en) | 2002-04-15 |
Family
ID=16596071
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| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP21084595A Expired - Lifetime JP3274955B2 (en) | 1995-08-18 | 1995-08-18 | Method for producing synthetic quartz glass base material for optical components for use in ultraviolet region, and method for producing synthetic quartz glass material |
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| Country | Link |
|---|---|
| JP (1) | JP3274955B2 (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001302274A (en) * | 2000-04-24 | 2001-10-31 | Sumitomo Metal Ind Ltd | Quartz glass for ultraviolet light and method for producing the same |
| JP2006188424A (en) * | 2004-12-29 | 2006-07-20 | Corning Inc | High transmission synthetic silica glass and method of making same |
| JP2006213570A (en) * | 2005-02-04 | 2006-08-17 | Asahi Glass Co Ltd | Method of manufacturing synthetic quartz glass and synthetic quartz glass for optical member |
| WO2007086611A1 (en) * | 2006-01-30 | 2007-08-02 | Asahi Glass Co., Ltd. | Synthetic quartz glass with radial distribution of fast axes of birefringence and process for producing the same |
| JP2013006722A (en) * | 2011-06-23 | 2013-01-10 | Sumitomo Electric Ind Ltd | Method for producing base material for synthetic quartz glass and base material for synthetic quartz glass |
-
1995
- 1995-08-18 JP JP21084595A patent/JP3274955B2/en not_active Expired - Lifetime
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2001302274A (en) * | 2000-04-24 | 2001-10-31 | Sumitomo Metal Ind Ltd | Quartz glass for ultraviolet light and method for producing the same |
| JP2006188424A (en) * | 2004-12-29 | 2006-07-20 | Corning Inc | High transmission synthetic silica glass and method of making same |
| JP2006213570A (en) * | 2005-02-04 | 2006-08-17 | Asahi Glass Co Ltd | Method of manufacturing synthetic quartz glass and synthetic quartz glass for optical member |
| WO2006082983A3 (en) * | 2005-02-04 | 2006-10-26 | Asahi Glass Co Ltd | Process for producing synthetic quartz glass and synthetic quartz glass for optical member |
| US7975507B2 (en) | 2005-02-04 | 2011-07-12 | Asahi Glass Company, Limited | Process for producing synthetic quartz glass and synthetic quartz glass for optical member |
| WO2007086611A1 (en) * | 2006-01-30 | 2007-08-02 | Asahi Glass Co., Ltd. | Synthetic quartz glass with radial distribution of fast axes of birefringence and process for producing the same |
| JP2013006722A (en) * | 2011-06-23 | 2013-01-10 | Sumitomo Electric Ind Ltd | Method for producing base material for synthetic quartz glass and base material for synthetic quartz glass |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3274955B2 (en) | 2002-04-15 |
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