JPH0656448A - Production of optical fiber preform - Google Patents
Production of optical fiber preformInfo
- Publication number
- JPH0656448A JPH0656448A JP4235195A JP23519592A JPH0656448A JP H0656448 A JPH0656448 A JP H0656448A JP 4235195 A JP4235195 A JP 4235195A JP 23519592 A JP23519592 A JP 23519592A JP H0656448 A JPH0656448 A JP H0656448A
- Authority
- JP
- Japan
- Prior art keywords
- burner
- flame
- rod
- silica
- polishing
- 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
- 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]
- C03B37/0148—Means for heating preforms during or immediately prior to deposition
-
- 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
- C03B2207/50—Multiple burner arrangements
- C03B2207/54—Multiple burner arrangements combined with means for heating the deposit, e.g. non-deposition burner
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P40/00—Technologies relating to the processing of minerals
- Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
- Y02P40/57—Improving the yield, e-g- reduction of reject rates
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Geochemistry & Mineralogy (AREA)
- Manufacturing & Machinery (AREA)
- Materials Engineering (AREA)
- Organic Chemistry (AREA)
- Glass Melting And Manufacturing (AREA)
- Manufacture, Treatment Of Glass Fibers (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】この発明は、外付け法による光フ
ァイバ母材の製造方法に関するもので、生産性向上を図
ったものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing an optical fiber preform by an external attachment method, which is intended to improve productivity.
【０００２】[0002]
【従来の技術】光ファイバ母材の製造工程のひとつに外
付け工程というものがある。これはコアとなる部分を含
む石英系ガラスロッドの周りに、クラッドとなるガラス
微粒子を堆積させる工程であるが、その前工程として火
炎研磨という工程があって石英系ガラスロッド表面の汚
れや微細な傷の除去を行なっている。具体的には、一本
の火炎研磨用のバーナと少なくとも一本のガラス微粒子
生成用バーナとを近接して基台に固定し、この基台をガ
ラスロッドの軸方向にトラバースするように構成し、当
初は基台をトラバースさせながら火炎研磨用のバーナの
みを用いてガラスロッドを研磨する。その後、火炎研磨
用バーナへの燃焼ガスの供給を停止し、ガラス微粒子生
成用バーナを用いてガラスロッドの周りにガラス微粒子
層を堆積させる。2. Description of the Related Art One of the manufacturing processes of an optical fiber preform is an external mounting process. This is a step of depositing fine glass particles to be the clad around the silica-based glass rod including the part to be the core, but there is a step of flame polishing as a pre-step, which is a step of dirt and fine particles on the surface of the silica-based glass rod. We are removing scratches. Specifically, one flame polishing burner and at least one glass fine particle generating burner are fixed in close proximity to the base, and the base is configured to traverse in the axial direction of the glass rod. , Initially, the glass rod is polished by using only the burner for flame polishing while traversing the base. After that, the supply of the combustion gas to the burner for flame polishing is stopped, and the glass fine particle layer is deposited around the glass rod using the burner for producing glass fine particles.
【０００３】[0003]
【発明が解決しようとする課題】しかし、外付け工程の
効率化を考えるとき、本来母材製造に関与しない火炎研
磨時間は短縮できた方が望ましい。また、外付けされる
ガラスロッド径を太くできれば、その上に堆積されるガ
ラス微粒子の堆積速度を向上させることが可能となる。
このような要求に対しては火炎研磨の火力を強める必要
があるが一本のバーナではこの要求に対応するには限界
がある。例えば、既存のバーナ、ガス系で供給可能な酸
水素量には上限があり、またガス系を代えて火力の強い
ものにすると急加熱になってロッドが撓むという懸念が
あるからである。そこで、既存の火炎研磨用バーナを複
数本用いることが考えられるが、ガス系が複雑になるの
みならず、これらバーナは前述のようにガラス微粒子生
成時には使用しないものであるので邪魔にならないよう
できれば少ない方が良い。However, when considering the efficiency of the external attachment process, it is desirable that the flame polishing time, which is not originally involved in the production of the base material, can be shortened. Further, if the diameter of the glass rod to be externally attached can be increased, the deposition rate of the glass fine particles deposited thereon can be improved.
In order to meet such requirements, it is necessary to increase the flame polishing power, but there is a limit to the ability of one burner to meet this requirement. For example, there is an upper limit to the amount of oxyhydrogen that can be supplied by an existing burner or gas system, and if the gas system is changed to one having a strong thermal power, there is a concern that the rod may be bent due to rapid heating. Therefore, it is conceivable to use a plurality of existing flame polishing burners, but not only the gas system becomes complicated, but these burners are not used at the time of producing glass particles as described above, so if it can be prevented from interfering. The less the better.
【０００４】[0004]
【課題を解決するための手段】この発明は、以上の観点
にたってなされたもので、その特徴とする請求項１記載
の発明は、少なくともコアとなる部分を含む石英系ガラ
スロッドを火炎研磨した後、その周りに外付け法により
クラッドとなる石英系ガラス微粒子層を堆積させるに際
して、互いに近接して配置された火炎研磨用バーナと石
英系ガラス微粒子生成用バーナとを用い、かつ当初は石
英系ガラス微粒子生成用バーナにはガラス生成用原料ガ
スを供給することなく燃焼ガスのみ供給して、両バーナ
にて石英系ガラスロッドを火炎研磨し、次いで火炎研磨
用バーナへの燃焼ガスの供給は停止し、石英系ガラス微
粒子生成用バーナにはガラス生成用原料ガスを供給して
前記火炎研磨済みの石英系ガラスロッドの周りに外付け
法によりクラッドとなる石英系ガラス微粒子層を堆積さ
せる光ファイバ母材の製造方法にある。また、その特徴
とする請求項２記載の発明は、請求項１においてバーナ
が中央に位置する火炎研磨用バーナと、その両側に近接
して配置された一対の石英系ガラス微粒子生成用バーナ
とからなることにある。The present invention has been made from the above point of view, and the invention according to claim 1 is characterized in that a quartz glass rod including at least a core portion is flame-polished. After that, when depositing a silica-based glass fine particle layer to be a clad around it by an external method, a flame-polishing burner and a silica-based glass fine particle-producing burner arranged close to each other were used, and initially a quartz-based burner was used. Only the combustion gas is supplied to the burner for producing glass particles without supplying the raw material gas for producing glass, the quartz glass rod is flame-polished by both burners, and then the supply of the combustion gas to the burner for flame polishing is stopped. Then, the raw material gas for glass production is supplied to the burner for producing silica-based glass particles, and the burner for producing glass is clad around the flame-polished silica-based glass rod by an external method. In the method for manufacturing an optical fiber preform to deposit the silica-based glass fine particle layer composed. Further, the invention according to claim 2 is characterized in that, in claim 1, the burner for flame polishing has a burner located at the center, and a pair of burners for producing silica-based glass fine particles arranged close to both sides thereof. Is to be.
【０００５】[0005]
【作用】石英系ガラスロッドの火炎研磨時には、火炎研
磨用バーナと、本来はガラス微粒子生成用バーナである
が、ガラス微粒子生成ガスの供給は停止され燃焼ガスの
み供給されるようになされたバーナとを用いて火炎研磨
を行なうようにしたため、従来のガス系をそのまま使用
して、しかも効率良い火炎研磨が可能となる。ガラス微
粒子生成用バーナには、もともと酸素と水素ガスの供給
量がガラス微粒子生成に足る量だけしか供給されず火炎
研磨用バーナの火力と比較すると弱いのでバーナを両方
同時に用いてもその火力のために石英系ガラスロッドが
撓むといったことはない。When the quartz-based glass rod is flame-polished, the burner for flame-polishing and the burner originally for producing fine glass particles, which is designed to stop the supply of fine-particle-producing gas and to supply only combustion gas, are used. Since the flame polishing is performed by using, the conventional gas system can be used as it is, and the flame polishing can be efficiently performed. Originally, the amount of oxygen and hydrogen gas supplied to the glass particle generation burner was only sufficient to generate glass particles, which is weak compared to the flame power of a flame polishing burner. The quartz glass rod does not bend.
【０００６】[0006]
（実施例１）図１は、この発明の実施例を示す概略説明
図である。図において、１は石英系ガラスロッドで、例
えばコアとなるＳｉＯ2 −ＧｅＯ2 ガラスロッドの周り
にクラッドの一部をなすＳｉＯ2 ガラス層が形成されて
なるもので、火炎研磨時および残りのクラッド用ＳｉＯ
2 ガラス微粒子堆積時を通じてその軸の周りに回転され
る。２は基台で、後述する一対のバーナを近接して固定
するとともに、前記ロッド１の軸方向に添ってトラバー
スされる。３、４はそれぞれ火炎研磨用バーナ、ＳｉＯ
2 ガラス微粒子生成用バーナで、ロッド１に対峙してお
り前述したように基台２に近接して固定されている。以
上の構成において、まず火炎研磨用バーナ３にＨ2 １６
０リットル／分、Ｏ2 ８０リットル／分供給するととも
に、ＳｉＯ2 ガラス微粒子生成用バーナ４にはガラス原
料ガスを供給せずＨ2 を８０リットル／分、Ｏ2 を４０
リットル／分のみ供給しつつロッド１の軸に添って一端
から他端まで６０ｍｍ／分の速度でトラバースした。な
お、その際ロッド１として直径２０ｍｍのものを用い、
その軸の周りに２０ｒｐｍで回転させた。得られたロッ
ド１の表面を確認したところ、傷や汚れはなく清浄な表
面であった。引続いて火炎研磨用バーナ３へのガス供給
を停止し、ガラス微粒子生成用バーナ４にはＨ2 を４０
リットル／分、Ｏ2 を２０リットル／分、ＳｉＣｌ4 を
５リットル／分供給して火炎加水分解反応および熱酸化
反応によってロッド１の周りにＳｉＯ2 ガラス微粒子を
層状に堆積させた。次いで、このＳｉＯ2 ガラス微粒子
層を有するロッドを塩素ガス雰囲気で脱水し、しかる後
Ｈｅ雰囲気で透明ガラス化して所望の光ファイバ母材と
した。因みに、従来の火炎研磨用バーナ３のみを用いて
ロッド１を火炎研磨し、所定の清浄な表面を得るには２
回のトラバースが必要であった。(Embodiment 1) FIG. 1 is a schematic explanatory view showing an embodiment of the present invention. In the figure, reference numeral 1 is a silica-based glass rod, for example, which is formed by forming a SiO 2 glass layer forming a part of the clad around a SiO 2 —GeO 2 glass rod to be a core, during the flame polishing and the remaining clad. For SiO
2 Glass particles are rotated around their axis during the deposition. Reference numeral 2 denotes a base, which fixes a pair of burners described later in close proximity and is traversed along the axial direction of the rod 1. 3 and 4 are flame polishing burners and SiO, respectively
2 A burner for producing fine glass particles, which faces the rod 1 and is fixed close to the base 2 as described above. In the above configuration, first, the flame polishing burner 3 is provided with H 2 16
While supplying 0 liter / min and O 2 80 liter / min, the glass raw material gas was not supplied to the SiO 2 glass fine particle generation burner 4 and H 2 was 80 liter / min and O 2 was 40
While supplying only liter / minute, the rod 1 was traversed along the axis of the rod 1 from one end to the other end at a speed of 60 mm / min. At that time, the rod 1 having a diameter of 20 mm is used,
It was rotated around its axis at 20 rpm. When the surface of the obtained rod 1 was checked, it was a clean surface without scratches or stains. Subsequently, the gas supply to the burner 3 for flame polishing was stopped, and H 2 was added to the burner 4 for producing fine glass particles at 40%.
L 2 / minute, O 2 20 liter / minute, and SiCl 4 5 liter / minute were supplied to deposit SiO 2 glass fine particles in layers around the rod 1 by flame hydrolysis reaction and thermal oxidation reaction. Next, the rod having this SiO 2 glass fine particle layer was dehydrated in a chlorine gas atmosphere, and then transparent vitrified in a He atmosphere to obtain a desired optical fiber preform. Incidentally, in order to obtain a predetermined clean surface by flame-polishing the rod 1 using only the conventional burner 3 for flame-polishing,
One traverse was needed.
【０００７】（実施例２）火炎研磨用バーナ３を中心に
して、その両側にガラス微粒子生成用バーナ４、４を位
置させ、火炎研磨時には火炎研磨用バーナ３とこの両バ
ーナ４、４の計３本のバーナを用いた。これらバーナ
３、４、４への燃焼ガス供給量および他の条件は実施例
１と同等とした。得られたロッド１の表面は、実施例１
と同様に清浄であった。その後、火炎研磨用バーナ３へ
のガス供給を停止し、ガラス微粒子生成用バーナ４、４
にＨ2 を４０リットル／分、Ｏ2 を２０リットル／分、
ＳｉＣｌ4 を５リットル／分供給して石英系ガラス微粒
子をロッド１上に堆積させ、以下実施例１と同様にして
光ファイバ母材とした。(Embodiment 2) The burner 3 for flame polishing is located at the center, and the burners 4, 4 for producing fine glass particles are located on both sides of the burner 3, and the burner 3 for flame polishing and both burners 4, 4 are combined for flame polishing. Three burners were used. The amount of combustion gas supplied to these burners 3, 4, and 4 and other conditions were the same as in Example 1. The surface of the obtained rod 1 is the same as in Example 1.
Was as clean as. After that, the gas supply to the burner 3 for flame polishing is stopped, and the burners 4, 4 for generating glass particles are generated.
H 2 at 40 l / min, O 2 at 20 l / min,
SiCl 4 was supplied at 5 liters / minute to deposit silica glass fine particles on the rod 1, and an optical fiber preform was prepared in the same manner as in Example 1.
【０００８】なお、実施例２におけるバーナ３、４、４
の３本を用い、火炎研磨はバーナ３とバーナ４、４のう
ちのいずれか１本を使用し、ガラス微粒子生成時にはバ
ーナ４、４を用いるということもできる。The burners 3, 4, 4 in the second embodiment
It can be said that any one of the burner 3 and the burners 4 and 4 is used for flame polishing, and the burners 4 and 4 are used at the time of producing glass particles.
【０００９】[0009]
【発明の効果】この発明方法によれば、従来ガラス微粒
子生成用にしか用いられていないバーナを火炎研磨用と
して火炎研磨用バーナとともに併用するようにしたの
で、コア用ロッドの研磨効率を向上できる。ガラス微粒
子生成用バーナへは本来ガラス微粒子生成に要する量の
酸水素量だけ供給されるようになっており、その量は火
炎研磨用バーナに供給される量よりも少ないので、両バ
ーナを火炎研磨用として併用しても火力が強すぎてロッ
ドが撓むといったことなく行なえる。According to the method of the present invention, since the burner which has been conventionally used only for producing fine glass particles is used together with the burner for flame polishing for flame polishing, the polishing efficiency of the core rod can be improved. . The amount of oxyhydrogen that is originally required to generate glass particles is supplied to the glass particle generation burner, which is less than the amount supplied to the flame polishing burner. Even if it is used together, it can be done without causing the rod to bend because the fire power is too strong.
【図１】この発明の実施例を示す概略説明図である。FIG. 1 is a schematic explanatory view showing an embodiment of the present invention.
１ コア用ロッド ２ 基台 ３ 火炎研磨用バーナ ４ ガラス微粒子生成用バーナ 1 Core Rod 2 Base 3 Flame Polishing Burner 4 Glass Fine Particle Generation Burner
Claims (2)
ガラスロッドを火炎研磨した後、その周りに外付け法に
よりクラッドとなる石英系ガラス微粒子層を堆積させる
に際して、互いに近接して配置された火炎研磨用バーナ
と石英系ガラス微粒子生成用バーナとを用い、かつ当初
は石英系ガラス微粒子生成用バーナにはガラス生成用原
料ガスを供給することなく燃焼ガスのみ供給して、両バ
ーナにて石英系ガラスロッドを火炎研磨し、次いで火炎
研磨用バーナへの燃焼ガスの供給は停止し、石英系ガラ
ス微粒子生成用バーナにはガラス生成用原料ガスを供給
して前記火炎研磨済みの石英系ガラスロッドの周りに外
付け法によりクラッドとなる石英系ガラス微粒子層を堆
積させることを特徴とする光ファイバ母材の製造方法。1. When flame-polishing a silica-based glass rod including at least a core portion and then depositing a silica-based glass fine particle layer serving as a cladding by an external attachment method, flames arranged in proximity to each other. A burner for polishing and a burner for producing silica-based glass fine particles are used, and at the beginning, the combustion gas is supplied to the burner for producing silica-based glass fine particles without supplying a raw material gas for producing glass, and both burners use a silica-based burner. The glass rod is flame-polished, then the supply of the combustion gas to the flame-polishing burner is stopped, and the glass-forming raw material gas is supplied to the burner for producing silica-based glass fine particles to supply the flame-polished quartz-based glass rod. A method for manufacturing an optical fiber preform, characterized in that a silica-based glass fine particle layer to be a clad is deposited around the periphery by an external method.
の両側に近接して配置された一対の石英系ガラス微粒子
生成用バーナを用いることを特徴とする請求項１記載の
光ファイバ母材の製造方法。2. The optical fiber preform according to claim 1, wherein a flame polishing burner located at the center and a pair of silica-based glass fine particle producing burners arranged on both sides of the burner are disposed in close proximity to each other. Production method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23519592A JP3340471B2 (en) | 1992-08-12 | 1992-08-12 | Manufacturing method of optical fiber preform |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP23519592A JP3340471B2 (en) | 1992-08-12 | 1992-08-12 | Manufacturing method of optical fiber preform |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH0656448A true JPH0656448A (en) | 1994-03-01 |
| JP3340471B2 JP3340471B2 (en) | 2002-11-05 |
Family
ID=16982493
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP23519592A Expired - Fee Related JP3340471B2 (en) | 1992-08-12 | 1992-08-12 | Manufacturing method of optical fiber preform |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP3340471B2 (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008081375A (en) * | 2006-09-28 | 2008-04-10 | Covalent Materials Corp | Method and apparatus for manufacturing silica glass |
| US8567217B2 (en) | 2003-05-09 | 2013-10-29 | Fujikura Ltd. | Optical fiber preform and manufacturing method therefor |
| CN111393016A (en) * | 2019-12-23 | 2020-07-10 | 杭州大和热磁电子有限公司 | Automatic fire polishing processing device |
-
1992
- 1992-08-12 JP JP23519592A patent/JP3340471B2/en not_active Expired - Fee Related
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8567217B2 (en) | 2003-05-09 | 2013-10-29 | Fujikura Ltd. | Optical fiber preform and manufacturing method therefor |
| JP2008081375A (en) * | 2006-09-28 | 2008-04-10 | Covalent Materials Corp | Method and apparatus for manufacturing silica glass |
| JP4605795B2 (en) * | 2006-09-28 | 2011-01-05 | コバレントマテリアル株式会社 | Silica glass body manufacturing method and silica glass body manufacturing apparatus |
| CN111393016A (en) * | 2019-12-23 | 2020-07-10 | 杭州大和热磁电子有限公司 | Automatic fire polishing processing device |
Also Published As
| Publication number | Publication date |
|---|---|
| JP3340471B2 (en) | 2002-11-05 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JPH0656448A (en) | Production of optical fiber preform | |
| JP4124198B2 (en) | Method of manufacturing optical fiber preform using MCVD method including dehydration and dechlorination processes, and optical fiber manufactured by this method | |
| JPH0463018B2 (en) | ||
| JP2612941B2 (en) | Method for producing porous optical fiber preform | |
| JP2002047027A (en) | Preform for optical fiber and single mode optical fiber | |
| JPH0788231B2 (en) | Manufacturing method of optical fiber preform | |
| JP3517848B2 (en) | Manufacturing method of optical fiber preform | |
| JPH04231336A (en) | Production of optical fiber preform | |
| JPH0525818B2 (en) | ||
| JPH0479981B2 (en) | ||
| JP2618260B2 (en) | Method for producing intermediate for optical fiber preform | |
| JPH06321552A (en) | Production of fluorine-doped quartz glass | |
| JPH06321553A (en) | Production of fluorine-doped quartz glass | |
| JPS61151031A (en) | Production of optical fiber preform | |
| JPS6136134A (en) | Method and apparatus for producing preform for stress-imparted polarization-keeping optical fiber | |
| JP3449488B2 (en) | Manufacturing method of preform for optical fiber | |
| JP3517250B2 (en) | Method for producing glass fiber preform for optical transmission line | |
| JPS5946898B2 (en) | Optical fiber manufacturing method | |
| JP3174682B2 (en) | Method for producing glass preform for optical fiber | |
| JPH0454625B2 (en) | ||
| JP2770103B2 (en) | Manufacturing method of optical fiber preform | |
| JP2006117496A (en) | Method for manufacturing optical fiber preform and method for manufacturing optical fiber | |
| JPH02124736A (en) | Production of optical fiber preform | |
| JPH0986948A (en) | Production of porous glass base material for optical fiber | |
| JPS593944B2 (en) | Optical fiber manufacturing method |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20070816 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080816 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20080816 Year of fee payment: 6 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090816 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20090816 Year of fee payment: 7 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20100816 Year of fee payment: 8 |
|
| FPAY | Renewal fee payment (prs date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110816 Year of fee payment: 9 |
|
| LAPS | Cancellation because of no payment of annual fees |