JPS6144822B2 - - Google Patents
Info
- Publication number
- JPS6144822B2 JPS6144822B2 JP58107217A JP10721783A JPS6144822B2 JP S6144822 B2 JPS6144822 B2 JP S6144822B2 JP 58107217 A JP58107217 A JP 58107217A JP 10721783 A JP10721783 A JP 10721783A JP S6144822 B2 JPS6144822 B2 JP S6144822B2
- Authority
- JP
- Japan
- Prior art keywords
- gas
- nozzle
- optical fiber
- sec
- base material
- 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.)
- Expired
Links
- 239000007789 gas Substances 0.000 claims description 20
- 239000011261 inert gas Substances 0.000 claims description 15
- 238000004519 manufacturing process Methods 0.000 claims description 13
- 239000013307 optical fiber Substances 0.000 claims description 8
- 239000002994 raw material Substances 0.000 claims description 7
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 claims description 5
- 238000000034 method Methods 0.000 claims description 3
- 239000007858 starting material Substances 0.000 claims description 3
- 239000011521 glass Substances 0.000 claims description 2
- 239000000203 mixture Substances 0.000 claims description 2
- 238000005245 sintering Methods 0.000 claims description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 claims 1
- 239000000567 combustion gas Substances 0.000 claims 1
- 229910001882 dioxygen Inorganic materials 0.000 claims 1
- 239000002245 particle Substances 0.000 claims 1
- 239000000463 material Substances 0.000 description 13
- 229910003902 SiCl 4 Inorganic materials 0.000 description 11
- 230000000903 blocking effect Effects 0.000 description 4
- 238000002485 combustion reaction Methods 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 238000007664 blowing Methods 0.000 description 2
- 230000008021 deposition Effects 0.000 description 2
- 239000000835 fiber Substances 0.000 description 2
- 239000001301 oxygen Substances 0.000 description 2
- 229910052760 oxygen Inorganic materials 0.000 description 2
- 239000010453 quartz Substances 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 239000004071 soot Substances 0.000 description 2
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910003910 SiCl4 Inorganic materials 0.000 description 1
- 229910052786 argon Inorganic materials 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- 125000004122 cyclic group Chemical group 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 229910052734 helium Inorganic materials 0.000 description 1
- 229910052743 krypton Inorganic materials 0.000 description 1
- 229910052754 neon Inorganic materials 0.000 description 1
- 230000000737 periodic effect Effects 0.000 description 1
- 230000001681 protective effect Effects 0.000 description 1
- 229910052704 radon Inorganic materials 0.000 description 1
- FDNAPBUWERUEDA-UHFFFAOYSA-N silicon tetrachloride Chemical compound Cl[Si](Cl)(Cl)Cl FDNAPBUWERUEDA-UHFFFAOYSA-N 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
- 229910052724 xenon Inorganic materials 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
- C03B37/01—Manufacture of glass fibres or filaments
- C03B37/012—Manufacture of preforms for drawing fibres or filaments
- C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
- C03B37/01413—Reactant delivery systems
- C03B37/0142—Reactant deposition burners
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2207/00—Glass deposition burners
- C03B2207/04—Multi-nested ports
- C03B2207/06—Concentric circular ports
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2207/00—Glass deposition burners
- C03B2207/20—Specific substances in specified ports, e.g. all gas flows specified
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2207/00—Glass deposition burners
- C03B2207/20—Specific substances in specified ports, e.g. all gas flows specified
- C03B2207/22—Inert gas details
-
- C—CHEMISTRY; METALLURGY
- C03—GLASS; MINERAL OR SLAG WOOL
- C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
- C03B2207/00—Glass deposition burners
- C03B2207/36—Fuel or oxidant details, e.g. flow rate, flow rate ratio, fuel additives
Description
【発明の詳細な説明】
本発明は光フアイバ製造方法のうち特にノズル
に損傷なく長期間安定して光フアイバ用プリフオ
ームを製造し得る方法に関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of manufacturing an optical fiber, and particularly to a method of manufacturing an optical fiber preform stably for a long period of time without damaging a nozzle.
従来複数のノズルを有する多重管バーナで、水
素単独又は水素と原料ガスの混合ガスを噴出させ
るノズルと酸素を噴出させるノズルを隣接させて
いたがこれらのノズルの出口において直ちに反応
燃焼することによりノズルの先端部が過熱され、
而も環元雰囲気となるため、損傷が早期に起りや
すく、従つて長期間に亘り再現性良く、品質、操
業状態を安定させて光フアイバ用プリフオームを
製造することができないという欠点があつた。 Conventionally, multi-tube burners have multiple nozzles, with a nozzle for ejecting hydrogen alone or a mixture of hydrogen and raw material gas and a nozzle for ejecting oxygen adjacent to each other. The tip of the is overheated,
However, since it is a cyclic atmosphere, damage is likely to occur early, and therefore optical fiber preforms cannot be manufactured over a long period of time with good reproducibility, quality, and stable operating conditions.
本発明は上記従来技術の欠点を除去しバーナノ
ズルの損傷を防止することにより長期に亘り安定
して光フアイバ用プリフオームを製造しうるよう
にするため開発された製造方法である。 The present invention is a manufacturing method developed to eliminate the drawbacks of the prior art described above and to prevent damage to the burner nozzle, thereby making it possible to manufacture optical fiber preforms stably over a long period of time.
本発明者等はこの欠点を防止するため鋭意研究
の結果水素噴出ノズルと酸素噴出ノズルの中間に
不活性ガス（Rnを除く）噴出ノズルを設けるこ
とが有効であることに着想するに到り更に多数の
試作を行なつた結果、不活性ガスの噴出流速を
0.1乃至1.5ｍ／secの範囲に設定することが前記
多重管バーナにより出発材の軸方向プリフオーム
母材を長期安定的に製造するには適切であること
がわかつた。 In order to prevent this drawback, the present inventors conducted intensive research and came up with the idea that it would be effective to provide an inert gas (excluding Rn) jetting nozzle between the hydrogen jetting nozzle and the oxygen jetting nozzle. As a result of numerous prototypes, we were able to determine the jetting flow rate of inert gas.
It has been found that setting the speed in the range of 0.1 to 1.5 m/sec is appropriate for producing the axial preform base material of the starting material stably over a long period of time using the multi-tube burner.
ここに前記不活性ガスには元素周期表のＯ族元
素、即ちHe，Ne，Ar，Kr，Xe，RnがあるがRn
を除く不活性ガスはいずれも本発明の場合に利用
することができる。Rnは放射能を有するので、
本発明製造方法への利用は好ましくない。また
Rnを除くこれらの不活性ガスのうち特にArは前
記不活性ガスでも比較的に化学的にも安定してい
るし、放射能もなく、空気中に略々１％存在して
資源的には比較的豊富といえるので、本発明製造
方法における利用しうる不活性ガスとして最も適
している。Heガスは熱伝導率が大きいという特
徴があり火炎内の温度を均一にする効果があり、
Arガスに混合して用いることが均一なスートを
製造する上で有効である。 Here, the inert gas includes O group elements of the periodic table of elements, namely He, Ne, Ar, Kr, Xe, and Rn, but Rn
Any inert gas except for can be utilized in the present invention. Since Rn has radioactivity,
Utilization in the manufacturing method of the present invention is not preferred. Also
Among these inert gases other than Rn, Ar in particular is relatively chemically stable even among the inert gases mentioned above, has no radioactivity, and exists at about 1% in the air, making it a valuable resource. Since it can be said to be relatively abundant, it is most suitable as an inert gas that can be used in the production method of the present invention. He gas is characterized by high thermal conductivity and has the effect of uniformizing the temperature within the flame.
Mixing it with Ar gas is effective in producing a uniform soot.
また本発明製造方法の場合において、前記不活
性ガスの作用は隣りのバーナから夫々噴出される
H2ガスとO2ガスの噴出された後の非常に短い時
間内におけるH2とO2の遮断により燃焼の時間を
僅かに遅らせバーナノズルから少し離れたところ
から燃焼が始まるようにしたことである。従つて
前記の遮断効果が有効に得られる範囲で前記不活
性ガスの噴出流速範囲が決められるべきである。
即ち本発明者等の実験によれば、不活性ガスのノ
ズルからの噴出流速が0.1ｍ／sec未満になると前
記H2とO2の遮断効果は弱く、燃焼が早くなり過
ぎてノズル先端の損傷が早くなり長期に亘り安定
してプリフオーム母材を製造することは不可能と
なる。また反対に不活性ガスの噴出流速が1.5
ｍ／secを超えるとSiCl4の付着収率が著しく低下
してくる。更にSiCl4の付着収率が低下すると排
気系の閉塞等により母材の製造が不安定になると
共にバーナを収納する保護容器の内壁面にスート
が多量に付着しかつ焼結後透明になるべきガラス
母材に気泡が発生する等々の致命的欠陥が生ず
る。其の上SiCl4の原料使用量も増大し無駄が多
くなり不経済となる。従つて本発明製造方法にお
いては不活性ガスの前記噴出流速は0.1乃至1.5
ｍ／secの範囲にすることが必要である。 Further, in the case of the manufacturing method of the present invention, the action of the inert gas is performed by blowing out each of the adjacent burners.
By blocking H 2 and O 2 within a very short period of time after the H 2 and O 2 gases are ejected, the combustion time is slightly delayed so that combustion starts a little further away from the burner nozzle. . Therefore, the flow velocity range of the inert gas should be determined within a range in which the above-mentioned blocking effect can be effectively obtained.
That is, according to experiments conducted by the present inventors, when the inert gas jet flow velocity from the nozzle is less than 0.1 m/sec, the blocking effect of H 2 and O 2 is weak, and combustion becomes too rapid, causing damage to the nozzle tip. This makes it impossible to stably manufacture a preform base material over a long period of time. On the other hand, the inert gas jet flow velocity is 1.5
If it exceeds m/sec, the deposition yield of SiCl 4 will drop significantly. Furthermore, if the deposition yield of SiCl 4 decreases, the production of the base material becomes unstable due to blockages in the exhaust system, etc., and a large amount of soot adheres to the inner wall of the protective container housing the burner, which should become transparent after sintering. Fatal defects such as bubbles occurring in the glass base material occur. Moreover, the amount of raw material SiCl 4 used increases, resulting in a lot of waste and becoming uneconomical. Therefore, in the production method of the present invention, the jetting flow rate of the inert gas is 0.1 to 1.5.
It is necessary to set it within the range of m/sec.
このような特性は次記の実験より明らかとなつ
た。 These characteristics were clarified through the following experiment.
すなわち、軸に垂直な断面が第１図に示される
ような多重管バーナを用い中央ノズル１から
SiCl4・GeCl4・H2を、第２ノズルからSiCl4・H2
を、第３ノズル３からArを、第４ノズル４から
O2を噴出させて前記方法を基本として出発材に
吹きつけ多孔質母材を製造した。そしてH2とO2
の極短時間の遮断用としてのArガスの適切な噴
出流速範囲とSiCl4原料ガスの収率（％）との関
係について実験を行なつた。この場合不活性ガス
の噴出流速はガスの流量実測値を20℃におけるも
のに換算した値を噴出ノズル断面積で除して求め
た。この実験の結果Arガスの噴出流速が0.1ｍ／
sec未満になると前記したように遮断効果は弱く
なり、H2の燃焼が早くなり過ぎてノズル先端の
損傷が早くなることがわかつた。またArガスの
噴出流速とSiCl4原料ガスの収率との関係を使用
した原料の量と得られた多孔質母材の量とから測
定した。其の結果は第２図に示す如くであり、
Arガスの噴出流速が1.5ｍ／secを超えるとSiCl4
の収率は著しく低下することがわかつた。この実
験により本発明方法の実施に際し、光フアイバ用
プリフオーム母材を長期に亘り安定的に而も経済
的に製造するためにはArの噴出流速は0.1乃至1.5
ｍ／secの範囲として操業することが必要である
ことがわかつた。 That is, using a multi-tube burner whose cross section perpendicular to the axis is shown in FIG.
SiCl 4・GeCl 4・H 2 from the second nozzle
, Ar from the third nozzle 3, and Ar from the fourth nozzle 4.
A porous base material was manufactured by blowing O 2 onto the starting material based on the method described above. and H2 and O2
An experiment was conducted to determine the relationship between the appropriate jetting flow rate range of Ar gas for extremely short-time interruption and the yield (%) of SiCl 4 raw material gas. In this case, the jet flow velocity of the inert gas was determined by converting the measured gas flow rate to that at 20° C. and dividing it by the cross-sectional area of the jet nozzle. As a result of this experiment, the Ar gas jet flow velocity was 0.1 m/
It was found that when the temperature is less than sec, the blocking effect weakens as described above, and the H 2 burns too quickly, leading to rapid damage to the nozzle tip. In addition, the relationship between the ejection flow rate of Ar gas and the yield of SiCl 4 raw material gas was measured from the amount of raw material used and the amount of porous base material obtained. The results are shown in Figure 2.
SiCl 4 when the Ar gas jet velocity exceeds 1.5 m/sec
It was found that the yield of was significantly reduced. This experiment revealed that when carrying out the method of the present invention, the Ar jet flow rate should be 0.1 to 1.5 in order to stably and economically produce the preform base material for optical fiber over a long period of time.
It has been found that it is necessary to operate in the m/sec range.
次に本発明の実施例につき述べる。 Next, examples of the present invention will be described.
比較例
石英製４重管バーナの中心ノズルからSiCl4100
ml／min、GeCl425ml／min、H2250ml／minを、
第２ノズルからSiCl490ml／minを、H22500ml／
minを、第３ノズルから遮断用ガスとしてAr1500
ml／minを、最外層ノズルからO26000ml／minを
夫々噴出させ多孔質母材を製造した。Arガスの
噴出流速は0.46ml／secであつた。こうして製造
した母材をHe雰囲気で焼結し透明化した。SiCl4
の収率は約80％であつた。更にこの母材を延伸
し、外径26mmφの石英管でジヤケツトしプリフオ
ームにした後グラフアイト抵抗炉で外径125μｍ
のフアイバに線引きした。このフアイバの伝送損
失、帯域を波長λ＝1.3μｍの光で評価したとこ
ろ0.5dB／Km、1.2GHz・Kmと夫々非常に良好な特
性を示した。Comparative example SiCl 4 100 from the center nozzle of a quartz quadruple tube burner
ml/min, GeCl 4 25ml/min, H 2 250ml/min,
SiCl 4 90ml/min from the second nozzle, H 2 2500ml/min
Ar1500 min is used as the cutoff gas from the third nozzle.
ml/min and 6000 ml/min of O 2 were ejected from the outermost layer nozzle to produce a porous base material. The Ar gas jet flow rate was 0.46 ml/sec. The base material thus produced was sintered in a He atmosphere to make it transparent. SiCl4
The yield was about 80%. This base material was further stretched and jacketed with a quartz tube with an outer diameter of 26 mmφ to form a preform, which was then heated in a graphite resistance furnace to an outer diameter of 125 μm.
A line was drawn on the fiber. When the transmission loss and bandwidth of this fiber were evaluated using light with a wavelength λ = 1.3 μm, they showed very good characteristics of 0.5 dB/Km and 1.2 GHz/Km, respectively.
実施例 ２
次にArガスのみを5600ml／minに増加し、他条
件は実施例１と同一として多孔性母材を作製し
た。即ち第３ノズルの断面は一定であるからAr
ガスの噴出流速は0.46×5600/1500＝1.72ｍ／sec
である。そして此の場合のSiCl4の収率を測定し
たところ49％と著しく低下した。また得られた多
孔質母材を前記同様にしてHe雰囲気下で焼結し
たが母材中に気泡が発生していることが観察さ
れ、また伝送帯域も140MHz・Kmと狭いものであ
つた。従つて本実施例においてもArガスの噴出
流速は0.1乃至1.5ｍ／secの範囲内にあることが
必要であることが再確認された。Example 2 Next, a porous base material was prepared by increasing only the Ar gas flow to 5600 ml/min and keeping the other conditions the same as in Example 1. In other words, since the cross section of the third nozzle is constant, Ar
Gas jet flow velocity is 0.46×5600/1500=1.72m/sec
It is. When the yield of SiCl 4 in this case was measured, it was significantly lower to 49%. In addition, when the obtained porous base material was sintered in a He atmosphere in the same manner as described above, it was observed that bubbles were generated in the base material, and the transmission band was also narrow at 140 MHz·Km. Therefore, it was reconfirmed that in this example as well, the ejection flow velocity of Ar gas must be within the range of 0.1 to 1.5 m/sec.
第１図はH2を含む原料ガスを噴出するノズル
とO2を噴出するノズルの間にArを噴出するノズ
ルを設けた多重管バーナの軸に垂直な断面図、第
２図はArガスの噴出流速とSiCl4原料ガスの収率
との関係を示す図である。
図において、１は中心ノズル、２は第２ノズ
ル、３は第３ノズル、４は最外層ノズルである。
Figure 1 is a cross-sectional view perpendicular to the axis of a multi-tube burner in which a nozzle for spouting Ar is installed between a nozzle for spouting raw material gas containing H 2 and a nozzle for spouting O 2 . FIG. 3 is a diagram showing the relationship between the ejection flow velocity and the yield of SiCl 4 source gas. In the figure, 1 is a center nozzle, 2 is a second nozzle, 3 is a third nozzle, and 4 is an outermost layer nozzle.
Claims (1)
を混合燃焼せしめて出発材の軸方向にガラス微粒
子を積層させ焼結して光フアイバ用プリフオーム
を製造する方法において、前記バーナの水素ガス
又は水素ガスとガラス原料ガスの混合ガスの噴出
ノズルと酸素ガス噴出ノズルの間のノズルから１
種類以上の不活性ガスを0.1乃至1.5ｍ／secの範
囲の流速で噴出させることを特徴とする光フアイ
バ用プリフオームの製造方法。 ２ 前記不活性ガスがArである特許請求の範囲
第１項に記載の光フアイバ用プリフオームの製造
方法。[Scope of Claims] 1. A method for producing an optical fiber preform by mixing and burning raw material gas and combustion gas using a multi-tube burner, stacking glass particles in the axial direction of a starting material, and sintering the mixture, the burner comprising: 1 from the nozzle between the hydrogen gas or mixed gas jetting nozzle of hydrogen gas and frit gas and the oxygen gas jetting nozzle.
A method for producing a preform for an optical fiber, characterized by ejecting inert gases of at least one type at a flow rate in the range of 0.1 to 1.5 m/sec. 2. The method for manufacturing an optical fiber preform according to claim 1, wherein the inert gas is Ar.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10721783A JPS59232933A (en) | 1983-06-15 | 1983-06-15 | Production of preform for optical fiber |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10721783A JPS59232933A (en) | 1983-06-15 | 1983-06-15 | Production of preform for optical fiber |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS59232933A JPS59232933A (en) | 1984-12-27 |
| JPS6144822B2 true JPS6144822B2 (en) | 1986-10-04 |
Family
ID=14453451
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10721783A Granted JPS59232933A (en) | 1983-06-15 | 1983-06-15 | Production of preform for optical fiber |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS59232933A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| KR100346220B1 (en) * | 2000-09-05 | 2002-08-01 | 삼성전자 주식회사 | Co-flow diffusion flame burner device for fabricating of optical waveguide |
| JP5658912B2 (en) | 2010-05-27 | 2015-01-28 | 株式会社フジクラ | Optical fiber preform manufacturing apparatus and manufacturing method |
| JP5793338B2 (en) | 2011-05-02 | 2015-10-14 | 株式会社フジクラ | Method and apparatus for manufacturing glass preform for optical fiber |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5595635A (en) * | 1979-01-08 | 1980-07-21 | Nippon Telegr & Teleph Corp <Ntt> | Production of glass base material for optical fiber |
| JPS5617936A (en) * | 1979-07-24 | 1981-02-20 | Nippon Telegr & Teleph Corp <Ntt> | Manufacture of base material for optical fiber |
| JPS5654244A (en) * | 1979-10-12 | 1981-05-14 | Hitachi Ltd | Preparation of optical fiber matrix |
| JPS57188424A (en) * | 1981-05-15 | 1982-11-19 | Nippon Telegr & Teleph Corp <Ntt> | Manufacture of base material for glass fiber |
| JPS57209839A (en) * | 1981-06-16 | 1982-12-23 | Nippon Telegr & Teleph Corp <Ntt> | Manufacturing of optical fiber |
-
1983
- 1983-06-15 JP JP10721783A patent/JPS59232933A/en active Granted
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5595635A (en) * | 1979-01-08 | 1980-07-21 | Nippon Telegr & Teleph Corp <Ntt> | Production of glass base material for optical fiber |
| JPS5617936A (en) * | 1979-07-24 | 1981-02-20 | Nippon Telegr & Teleph Corp <Ntt> | Manufacture of base material for optical fiber |
| JPS5654244A (en) * | 1979-10-12 | 1981-05-14 | Hitachi Ltd | Preparation of optical fiber matrix |
| JPS57188424A (en) * | 1981-05-15 | 1982-11-19 | Nippon Telegr & Teleph Corp <Ntt> | Manufacture of base material for glass fiber |
| JPS57209839A (en) * | 1981-06-16 | 1982-12-23 | Nippon Telegr & Teleph Corp <Ntt> | Manufacturing of optical fiber |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS59232933A (en) | 1984-12-27 |
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