JP2697898B2 - Method for producing hermetic coated optical fiber - Google Patents
Method for producing hermetic coated optical fiberInfo
- Publication number
- JP2697898B2 JP2697898B2 JP1113647A JP11364789A JP2697898B2 JP 2697898 B2 JP2697898 B2 JP 2697898B2 JP 1113647 A JP1113647 A JP 1113647A JP 11364789 A JP11364789 A JP 11364789A JP 2697898 B2 JP2697898 B2 JP 2697898B2
- Authority
- JP
- Japan
- Prior art keywords
- optical fiber
- reaction tube
- hermetic
- coated optical
- differential pressure
- 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 - Fee Related
Links
Landscapes
- Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)
- Surface Treatment Of Glass Fibres Or Filaments (AREA)
- Chemical Vapour Deposition (AREA)
Description
【発明の詳細な説明】 [産業上の利用分野] 本発明は、長期信頼性の高い光ファイバとして知られ
ているハーメチック被覆光ファイバの製造方法に関する
ものである。The present invention relates to a method for producing a hermetic coated optical fiber known as an optical fiber having high long-term reliability.
[従来の技術] 光ファイバは、石英ガラス等のガラスよりなり、これ
を長期間放置しておくと、水分が光ファイバ表面の微小
な傷に作用し、この傷を次第に増長させる。光ファイバ
は、布設の際にある程度の応力がかかった状態となり、
水分の存在する雰囲気では長期信頼性に欠けることにな
る。また、高温高湿等の悪環境下では、更に水分による
作用が増大し、著しく光ファイバの劣化が促進される。[Related Art] An optical fiber is made of glass such as quartz glass, and when left for a long period of time, moisture acts on minute scratches on the surface of the optical fiber, and the scratches gradually increase. The optical fiber is in a state where some stress is applied when laying,
In an atmosphere where moisture is present, long-term reliability is lacking. Further, in a bad environment such as high temperature and high humidity, the action of moisture further increases, and deterioration of the optical fiber is remarkably accelerated.
このような水分又は水分を誘発する水素の光ファイバ
への侵入を防ぐため、光ファイバの表面に高密度の無機
物膜等よりなる水封構造のハーメチック被覆を設けたハ
ーメチック被覆光ファイバが知られている。A hermetic-coated optical fiber having a water-sealed hermetic coating made of a high-density inorganic film or the like on the surface of the optical fiber is known in order to prevent such moisture or moisture-induced hydrogen from entering the optical fiber. I have.
このような光ファイバへのハーメチック被覆は、コー
ティング法,プラズマCVD法,熱CVD法等により成膜が行
われる。Hermetic coating on such an optical fiber is performed by a coating method, a plasma CVD method, a thermal CVD method, or the like.
上記のようないずれの方法で行うにしても、ハーメチ
ック被覆は、光ファイバの長手方向に均一な膜として設
ける必要がある。Whichever method is used, the hermetic coating needs to be provided as a uniform film in the longitudinal direction of the optical fiber.
第3図は、前述した各方法のうちハーメチック被覆を
長手方向に均一に設けるのに通した方法として知られて
いる熱CVD法によるハーメチック被覆光ファイバの製造
方法を実施する装置の一例を示したものである。この場
合には、光ファイバ母材1を線引炉2で加熱し軟化させ
て線引きし、光ファイバ3を得る。得られた光ファイバ
3は、外径測定器4に通し、その外径を測定した後、反
応管5に通す。反応管5内には、原料ガス導入管6を通
してC2H2等の原料ガス、He,N2,Ar等の稀釈ガスを導入す
る。これらガスは、該反応管5の外に設けられた電気抵
抗炉,赤外線放射加熱炉,高周波誘導加熱炉などの反応
管加熱炉7で加熱する。かくすると、反応管5内で熱CV
D反応が起こり、光ファイバ3の表面にC等の無機物質
よりなるハーメチック被覆8が成膜され、ハーメチック
被覆光ファイバ9が得られる。光ファイバ3に付着しな
かった反応生成物及び未反応ガスは、排気管10を経て外
部に排気される。FIG. 3 shows an example of an apparatus for carrying out a method of manufacturing a hermetic coated optical fiber by a thermal CVD method, which is known as a method for uniformly providing a hermetic coating in the longitudinal direction among the above-described methods. Things. In this case, the optical fiber preform 1 is heated in a drawing furnace 2 to be softened and drawn to obtain an optical fiber 3. The obtained optical fiber 3 is passed through an outer diameter measuring device 4, the outer diameter of which is measured, and then passed through a reaction tube 5. A source gas such as C 2 H 2 and a diluent gas such as He, N 2 and Ar are introduced into the reaction tube 5 through a source gas introduction tube 6. These gases are heated in a reaction tube heating furnace 7 such as an electric resistance furnace, an infrared radiation heating furnace, or a high frequency induction heating furnace provided outside the reaction tube 5. Thus, the heat CV in the reaction tube 5
A D reaction occurs, and a hermetic coating 8 made of an inorganic substance such as C is formed on the surface of the optical fiber 3 to obtain a hermetic coated optical fiber 9. Reaction products and unreacted gas that have not adhered to the optical fiber 3 are exhausted to the outside via an exhaust pipe 10.
[発明が解決しようとする課題] しかしながら、このようなハーメチック被覆光ファイ
バの製造方法では、光ファイバ3に付着しなかった反応
生成物11が排気管10の内壁に付着滞積し、排気管10の内
径を小さくするため、反応管5の内外の差圧が経時変化
を起こす。例えば、実験によると、実験開始後30分以内
に、反応管5の差圧(=内圧−外圧)が0.5mmH2O程度上
昇した。このような現象により、反応管5内の原料ガス
の流れが変化するため、長尺のハーメチック被覆光ファ
イバ9を製造する際に、光ファイバ3の表面に成膜され
るハーメチック被覆8の膜厚にむらが生じ、長手方向に
均一なハーメチック被覆8を形成することが困難な問題
点があった。[Problems to be Solved by the Invention] However, in such a method for producing a hermetic coated optical fiber, the reaction product 11 that has not adhered to the optical fiber 3 adheres and accumulates on the inner wall of the exhaust pipe 10 and the exhaust pipe 10 , The pressure difference between the inside and outside of the reaction tube 5 changes with time. For example, according to the experiment, the differential pressure (= internal pressure−external pressure) of the reaction tube 5 increased by about 0.5 mmH 2 O within 30 minutes after the start of the experiment. Due to such a phenomenon, the flow of the raw material gas in the reaction tube 5 changes. Therefore, when the long hermetic coated optical fiber 9 is manufactured, the film thickness of the hermetic coating 8 formed on the surface of the optical fiber 3 is reduced. In this case, there is a problem that it is difficult to form a uniform hermetic coating 8 in the longitudinal direction.
本発明の目的は、ハーメチック被覆を長手方向に均一
に成膜するのを容易に行うことができるハーメチック被
覆光ファイバの製造方法を提供することにある。An object of the present invention is to provide a method of manufacturing a hermetic coated optical fiber that can easily form a hermetic coating uniformly in a longitudinal direction.
[課題を解決するための手段] 上記の目的を達成するための本発明の手段を説明する
と、本発明は反応管内に光ファイバを通し、該反応管内
に原料ガスを供給して気相成長法により前記光ファイバ
の表面にハーメチック被覆を成膜させてハーメチック被
覆光ファイバを製造する方法において、前記反応管の内
外の差圧を測定し、該差圧が一定になるように前記反応
管からの排気を制御することを特徴とする。[Means for Solving the Problems] The means of the present invention for achieving the above object will be described. The present invention is directed to a method in which an optical fiber is passed through a reaction tube, and a raw material gas is supplied into the reaction tube. In a method of producing a hermetic coated optical fiber by forming a hermetic coating on the surface of the optical fiber, a differential pressure between the inside and outside of the reaction tube is measured, and the pressure from the reaction tube is measured so that the differential pressure becomes constant. It is characterized by controlling exhaust.
[作用] このように、反応管の内外の差圧を一定にするように
制御すると、反応管内の原料ガスの流れの状態が経時変
化することなく一定に保たれるため、ハーメチック被覆
が光ファイバの長手方向に均一に成膜されるハーメチッ
ク被覆光ファイバの製造を容易に行うことができる。[Operation] As described above, when the differential pressure between the inside and outside of the reaction tube is controlled to be constant, the state of the flow of the raw material gas in the reaction tube is kept constant without changing over time, so that the hermetic coating is applied to the optical fiber. It is possible to easily manufacture a hermetic coated optical fiber that is uniformly formed in the longitudinal direction.
[実施例] 以下、本発明の実施例を図面を参照して詳細に説明す
る。なお、前述した第3図と対応する部分には同一符号
を付けて示している。Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Parts corresponding to those in FIG. 3 are denoted by the same reference numerals.
第1図は、本発明の第1実施例を示したものである。
本実施例では、反応管5に差圧計12を接続し、また排気
管10には調整弁13を接続する。かくして、該差圧計12で
反応管5の内外の差圧(=内圧−外圧)を測定し、得ら
れた差圧データを制御器14に入力し、該差圧が一定にな
るように調整弁13を徐々に開く制御をする。FIG. 1 shows a first embodiment of the present invention.
In the present embodiment, a differential pressure gauge 12 is connected to the reaction tube 5, and a regulating valve 13 is connected to the exhaust pipe 10. Thus, the differential pressure between the inside and outside of the reaction tube 5 (= internal pressure-external pressure) is measured by the differential pressure gauge 12, and the obtained differential pressure data is input to the controller 14, and the regulating valve is adjusted so that the differential pressure becomes constant. Control to open 13 gradually.
第2図は、本発明の第2実施例を示したものである。
本実施例では、反応管5に差圧計12を接続し、排気管10
に吸気管15を接続し、該吸気管15に調整弁13を接続し、
差圧計12で測定した反応管5の内外の差圧を制御器14に
入力し、該差圧が一定になるように調整弁13を制御す
る。即ち、排気管10を図示しない吸引手段で一定圧力で
減圧しつつ、反応管5の内外の差圧が大きくなるにつれ
て、調整弁13を徐々に閉じ、吸気管15から吸い込む空気
量を少なくし、反応管5の吸引圧力を徐々に高め、該反
応管5の内外の差圧が一定になるように制御する。FIG. 2 shows a second embodiment of the present invention.
In this embodiment, a differential pressure gauge 12 is connected to the reaction
Is connected to the intake pipe 15, the adjustment valve 13 is connected to the intake pipe 15,
The differential pressure between the inside and outside of the reaction tube 5 measured by the differential pressure gauge 12 is input to the controller 14, and the regulating valve 13 is controlled so that the differential pressure becomes constant. That is, while the exhaust pipe 10 is depressurized at a constant pressure by a suction means (not shown), as the differential pressure between the inside and outside of the reaction pipe 5 increases, the regulating valve 13 is gradually closed to reduce the amount of air sucked from the intake pipe 15, The suction pressure of the reaction tube 5 is gradually increased to control the pressure difference between the inside and outside of the reaction tube 5 to be constant.
このような制御方法は、第1実施例よりも精密な制御
が可能である。また、吸気管15は複数本設けることもで
きる。このようにすると、排気能力の制御幅が広がる。Such a control method allows more precise control than in the first embodiment. Further, a plurality of intake pipes 15 may be provided. By doing so, the control range of the exhaust capacity is widened.
なお、上記実施例では、熱CVD法に本発明を適用した
場合について示したが、ハーメチック被覆をプラズマCV
D法等の他の方法で成膜する方法にも本発明は同様に適
用できるものである。In the above embodiment, the case where the present invention is applied to the thermal CVD method is described.
The present invention can be similarly applied to a method of forming a film by another method such as the D method.
[発明の効果] 以上説明したように本発明に係るハーメチック被覆光
ファイバの製造方法は、反応管の内外の差圧を一定にす
るように制御するので、反応管内の原料ガスの流れの状
態が経時変化することなく一定に保たれ、従って光ファ
イバの長手方向に均一な膜厚のハーメチック被覆を有す
る長尺のハーメチック被覆光ファイバの製造を容易に行
うことができる。[Effect of the Invention] As described above, the method of manufacturing the hermetic coated optical fiber according to the present invention controls the differential pressure between the inside and outside of the reaction tube to be constant, so that the state of the flow of the source gas in the reaction tube is A long hermetic coated optical fiber having a uniform thickness in the longitudinal direction of the optical fiber, which is kept constant without changing over time, can be easily manufactured.
第1図及び第2図は本発明に係るハーメチック被覆光フ
ァイバの製造方法を実施する装置の第1,第2実施例の概
略構成を示す縦断面図、第3図は従来の装置の縦断面図
である。 1……光ファイバ母材、2……線引炉、3……光ファイ
バ、4……外径測定器、5……反応炉、6……原料ガス
導入管、7……反応管加熱炉、8……ハーメチック被
覆、9……ハーメチック被覆光ファイバ、10……排気
管、11……反応生成物、12……差圧計、13……調整弁、
14……制御器、15……吸気管。1 and 2 are longitudinal sectional views showing a schematic configuration of first and second embodiments of an apparatus for implementing a method of manufacturing a hermetic coated optical fiber according to the present invention, and FIG. 3 is a longitudinal section of a conventional apparatus. FIG. DESCRIPTION OF SYMBOLS 1 ... Optical fiber preform, 2 ... Drawing furnace, 3 ... Optical fiber, 4 ... Outer diameter measuring device, 5 ... Reaction furnace, 6 ... Source gas introduction pipe, 7 ... Reaction tube heating furnace , 8 Hermetic coating, 9 Hermetic coated optical fiber, 10 Exhaust pipe, 11 Reaction product, 12 Differential pressure gauge, 13 Regulator valve,
14 ... Controller, 15 ... Intake pipe.
Claims (1)
に原料ガスを供給して気相成長法により前記光ファイバ
の表面にハーメチック被覆を成膜させてハーメチック被
覆光ファイバを製造する方法において、前記反応管の内
外の差圧を測定し、該差圧が一定になるように前記反応
管からの排気を制御することを特徴とするハーメチック
被覆光ファイバの製造方法。1. A method for producing a hermetic-coated optical fiber by passing an optical fiber through a reaction tube, supplying a raw material gas into the reaction tube, and forming a hermetic coating on the surface of the optical fiber by a vapor phase growth method. Measuring the pressure difference between the inside and outside of the reaction tube, and controlling the exhaust from the reaction tube so that the pressure difference becomes constant.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP1113647A JP2697898B2 (en) | 1989-05-08 | 1989-05-08 | Method for producing hermetic coated optical fiber |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP1113647A JP2697898B2 (en) | 1989-05-08 | 1989-05-08 | Method for producing hermetic coated optical fiber |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH02293353A JPH02293353A (en) | 1990-12-04 |
JP2697898B2 true JP2697898B2 (en) | 1998-01-14 |
Family
ID=14617557
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP1113647A Expired - Fee Related JP2697898B2 (en) | 1989-05-08 | 1989-05-08 | Method for producing hermetic coated optical fiber |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP2697898B2 (en) |
-
1989
- 1989-05-08 JP JP1113647A patent/JP2697898B2/en not_active Expired - Fee Related
Also Published As
Publication number | Publication date |
---|---|
JPH02293353A (en) | 1990-12-04 |
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Legal Events
Date | Code | Title | Description |
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LAPS | Cancellation because of no payment of annual fees |