JP2004345924A - Manufacturing method of glass preform for optical fiber - Google Patents

Manufacturing method of glass preform for optical fiber Download PDF

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JP2004345924A
JP2004345924A JP2003146769A JP2003146769A JP2004345924A JP 2004345924 A JP2004345924 A JP 2004345924A JP 2003146769 A JP2003146769 A JP 2003146769A JP 2003146769 A JP2003146769 A JP 2003146769A JP 2004345924 A JP2004345924 A JP 2004345924A
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glass layer
reaction tube
deposition
manufacturing
optical fiber
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JP4203731B2 (en
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Shinji Endo
信次 遠藤
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Sumitomo Electric Industries Ltd
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Sumitomo Electric Industries Ltd
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    • 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]
    • C03B37/018—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] by glass deposition on a glass substrate, e.g. by inside-, modified-, plasma-, or plasma modified- chemical vapour deposition [ICVD, MCVD, PCVD, PMCVD], i.e. by thin layer coating on the inside or outside of a glass tube or on a glass rod
    • C03B37/01807—Reactant delivery systems, e.g. reactant deposition burners
    • C03B37/01815—Reactant deposition burners or deposition heating means
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2207/00—Glass deposition burners
    • C03B2207/60—Relationship between burner and deposit, e.g. position
    • C03B2207/66—Relative motion
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2207/00—Glass deposition burners
    • C03B2207/70—Control measures

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  • 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)
  • Manufacture, Treatment Of Glass Fibers (AREA)

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of manufacturing a glass preform for an optical fiber capable of decreasing the characteristics variation in the direction of its length by making the thickness of the glass layer deposited in a reactor tube uniform. <P>SOLUTION: In this method, a reactor tube 20 is rotated while supplying a feed gas from upstream, and it is heated by a heat source 17 which is moved back and forth in the direction of the length of the reactor tube 20, and a glass layer 22 is deposited in the reaction tube 20. In this case, the upstream end of the movement of the heat source 17, which is the starting point of the deposit PUi, is moved stepwise toward the upstream, thus the transient condition from the starting point of deposit PUi to the point where an equilibrium condition of the reaction is reached, which extends by increasing the thickness of the reactor tube 20 with the deposit, is moved to the upstream of an effective part, and the deposit of the glass layer in the effective part is made uniform. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

【０００１】
【発明の属する技術分野】
この発明は、光ファイバ用ガラス母材の製造方法に関するものである。
【０００２】
【従来の技術】
従来の光ファイバ用ガラス母材の製造方法および製造装置として、石英からなる反応管を回転させ、反応管の内部に原料ガスを供給するとともに反応管を外側から加熱することにより、反応管の内面にガラス層を堆積させるいわゆるＭＣＶＤ法によるものが開示されている（例えば、特許文献１参照。）。
この特許文献１に示されているＭＣＶＤ法では、加熱源を反応管の外側において軸方向に沿って往復移動させる際に、下流側の移動終了端を徐々に上流側へ移動させるようにしている。これにより、ガラス層の堆積部分の末端における反応管の破損を防止するとともに、ススの堆積を低減している。
【０００３】
【特許文献１】
特開平６−２７１３２９号公報（第５−７頁、第１図）
【０００４】
【発明が解決しようとする課題】
ところで、ＭＣＶＤ法によるガラス堆積では、図３に示すように、堆積の開始側と終了側でガラス堆積量の違いが発生し、それがファイバ化したときに長手方向での特性変動の原因となる。
これは、図４に示すように、反応管１００の内部でガラス層１０１が生成される反応において、堆積開始時である上流側では内部温度が低いためガラスの生成量が少なく、その後徐々に堆積が進行して平衡状態に達するまでに時間差がある。その結果、図４に示すように、有効部におけるガラス層１０１の堆積量が上流側と下流側とで異なり、反応管１００の肉厚に差が生じるためである。
【０００５】
さらに、図５に示すように、ガラス層１０１が堆積して反応管１００の肉厚が厚くなるに従って、ガラス層１０１の堆積が平衡に達するまでの遅延も大きくなる。すなわち、肉厚が薄い場合の遅延時間ＴＬ０よりも肉厚が厚い場合の遅延時間ＴＬ１の方が長くなる（ＴＬ０＜ＴＬ１）。このことも、ファイバ化したときの特性の長手方向変動を引き起こす要因となる。
なお、図５においては、ガラス層１０１が堆積して反応管１００の肉厚が変化した場合を示し、反応管１００の表面温度は同一温度に設定されている。
【０００６】
本発明の目的は、反応管の内部に堆積するガラス層の厚さを均一にすることにより、長手方向の特性変動を小さくすることのできる光ファイバ用ガラス母材の製造方法を提供することにある。
【０００７】
【課題を解決するための手段】
前述した目的を達成するために、本発明にかかる光ファイバ用ガラス母材の製造方法は、回転する反応管の内部に上流側から原料ガスを供給し、前記反応管を外側から加熱する熱源を上流側から下流側へ移動させて前記反応管の内部にガラス層を堆積させる光ファイバ用ガラス母材の製造方法であって、堆積開始端を段階的に上流側へ移動させることを特徴としている。
【０００８】
このように構成された光ファイバ用ガラス母材の製造方法においては、反応管に上流側から原料ガスを供給しながら回転させ、熱源を反応管の長手方向へ往復移動させて加熱して反応管の内部にガラス層を堆積させる。この際に、堆積開始端である熱源の移動範囲の上流側端を段階的に上流側へ移動させる。これにより、堆積により反応管の肉厚が厚くなることに伴って伸びる堆積開始端から堆積が平衡状態になるまでの過渡状態を有効部よりも上流側へ移動させ、製造されるガラス母材の有効部におけるガラス層の堆積量を均一にする。
【０００９】
【発明の実施の形態】
以下、本発明に係る光ファイバ用ガラス母材の製造方法および製造装置の実施の形態を図面に基づいて詳細に説明する。なお、図１は本発明に係る光ファイバ用ガラス母材の製造装置の正面図、図２は本発明に係る光ファイバ用ガラス母材の製造方法および製造装置により製造したガラス母材におけるガラス層の堆積状態を示す断面図である。
【００１０】
図１に示すように、光ファイバ用ガラス母材の製造装置１０は、基台１１の上面１１ａの上流側端部（図１において左側端部）および下流側端部に支柱１２、１２が各々立設されている。支柱１２、１２の上端部には、石英からなる反応管２０を保持する保持部１３が回転自在に設けられている。基台１１の上面１１ａの両支柱１２、１２間には、熱源移動機構である台座１４がモータ１５により往復移動自在に設けられており、熱源１７が取り付けられている。なお、モータ１５は制御装置３０により制御される。
【００１１】
台座１４には位置検出器１６が取り付けられており、台座１４の位置を制御装置３０に伝達するようになっている。位置検出器１６としては、モータ１５にロータリーエンコーダを取り付けて、モータ１５の回転数から位置を検出するようにすることができる。あるいは、基台１１にリニアスケールを設けておき、台座１４に設けた検出子により位置を検出するようにすることもできる。
【００１２】
制御装置３０は、モータ１５を制御して台座１４を往復移動させるモータ制御部３１、熱源１７の移動範囲の上流側端である堆積開始端ＰＵｉ（図２参照）を往復移動回数に対応して段階的に上流側へ移動するように設定する往復範囲指令部３２、台座１４に設けられている位置検出器１６からの位置信号を受けて設定された往復範囲と比較する比較部３３等を備えている。
【００１３】
次に、本発明に係る光ファイバ用ガラス母材の製造方法について説明する。保持部１３により保持されている反応管２０を回転させながら、原料ガス供給手段２１が上流側から反応管２０の内部に例えば四塩化ケイ素、三塩化ホウ素等の原料ガスを供給する。そして、モータ１５により台座１４を移動させて、熱源１７を反応管２０の長手方向に沿って上流側から下流側へ往復移動しながら反応管２０を外側から加熱して、反応管２０の内部にガラス層２２（図２参照）を堆積させる。
【００１４】
このとき、制御装置３０の往復範囲指令部３２は堆積開始端ＰＵｉを段階的に上流側へ移動させて往復範囲を設定する。比較部３３は位置検出器１６からの位置信号と往復範囲とを比較し、台座１４が往復範囲に収まるように、モータ制御部３１が熱源移動機構のモータ１５を制御して台座１４を往復移動させる。
【００１５】
従って、図２に示されるように、堆積開始端ＰＵｉが上流側へ移動するに伴って、堆積が平衡となる位置も上流側へ移動することになる。これにより、図５において前述したように、ガラス層２２の堆積によって反応管２０の肉厚が厚くなることに伴い、堆積が平衡となるまでの時間が延びるのを吸収するので、有効部においては常に均一なガラス層２２の堆積が得られることになる。
なお、有効部の上流側に生じる非有効部が長くなるため、反応管２０の無駄を少なくするためにダミーパイプをつけるようにするのが好ましい。
【００１６】
次に、上述した光ファイバ用ガラス母材の製造方法および製造装置により製造した具体的な実施例について説明する。
表１には、本発明により堆積開始端ＰＵｉを上流側へ移動させながら製造した場合の堆積したガラス層２２の厚みと、従来の堆積開始端位置が一定の場合における堆積したガラス層の厚みを比較した結果が示されている。
なお、本発明における堆積開始端ＰＵｉの移動量は、熱源１７の２０往復ごとに５０ｍｍずつ上流側へ移動した。その他、熱源１７の温度や原料ガスの流量等は一定とした。
【００１７】
【表１】

Figure 2004345924
【００１８】
従来方式では、下流側に堆積したガラス層の厚さと上流側に堆積したガラス層の厚さの差は、堆積トラバース回数（熱源の往復回数）が２０のときに０．０１９ｍｍであり、その後４０回、６０回、８０回、１００回とトラバース回数にほぼ比例して厚さの差が増加している。すなわち、有効部においても下流側に堆積するガラス層が厚く、上流側に堆積するガラス層の厚さが小さくなっており、ガラス層の堆積量が長手方向に均一になっていないことがわかる。
【００１９】
一方、本発明では、下流側に堆積したガラス層２２の厚さと上流側に堆積したガラス層２２の厚さの差は、堆積トラバース回数が２０回の時と１００回の時とであまり差がない。従って、堆積トラバース回数が１００回の場合には、本発明の光ファイバ用ガラス母材の製造方法によると、上流側と下流側の厚さの差が従来式による場合と比較して約８分の１に小さくなっていることがわかる。すなわち、本発明では堆積するガラス層２２の厚さが、長手方向に均一となっていることがわかる。
【００２０】
以上、前述した光ファイバ用ガラス母材の製造方法および製造装置によれば、堆積開始端ＰＵｉである熱源１７の移動範囲の上流側端を段階的に上流側へ移動させることにより、堆積によって反応管２０の肉厚が厚くなることに伴って伸びる堆積開始端ＰＵｉから堆積が平衡状態になるまでの過渡状態を有効部よりも上流側へ移動させる。これにより、有効部におけるガラス層２２の堆積量を均一にすることができ、ファイバ化したときの長手方向の特性の変動を小さくすることができる。
【００２１】
なお、本発明の光ファイバ用ガラス母材の製造方法および製造装置は、前述した実施形態に限定されるものでなく、適宜な変形、改良等が可能である。
例えば、前述した製造装置１０における熱源移動機構として、台座１４に設けたモータ１５によって自走するタイプのものを例示したが、この他、モータにより回転するボールネジを反応管２０に沿って基台１１に設けておき、台座１４にこのボールネジに螺合しボールネジに沿って往復移動するボールナットを取り付けるようにしても良い。
【００２２】
【発明の効果】
以上、説明したように、本発明にかかる光ファイバ用ガラス母材の製造方法によれば、反応管に上流側から原料ガスを供給しながら回転させ、熱源を反応管の長手方向へ移動させて加熱して反応管の内部にガラス層を堆積させる。この際に、堆積開始端である熱源の移動範囲の上流側端を段階的に上流側へ移動させる。これにより、堆積により反応管の肉厚が厚くなることに伴って伸びる堆積開始端から反応が平衡状態になるまでの過渡状態を有効部よりも上流側へ移動させ、有効部におけるガラス層の堆積量を均一にすることができ、ファイバ化したときの長手方向の特性の変動を小さくすることができる。
【図面の簡単な説明】
【図１】本発明に係る光ファイバ用ガラス母材の製造装置の実施形態を示す構成図である。
【図２】本発明に係る光ファイバ用ガラス母材の製造方法および製造方法により反応管の内部に堆積したガラス層の厚さを示す断面図である。
【図３】従来より知られている堆積開始点から反応が平衡となるまでの過渡状態を示すグラフである。
【図４】従来法により反応管の内部に堆積したガラス層の厚さを示す断面図である。
【図５】反応管の肉厚と過渡状態の関係を示すグラフである。
【符号の説明】
１０ 光ファイバ用ガラス母材の製造装置
１５ モータ（熱源移動機構）
１７ 熱源
２０ 反応管
２１ 原料ガス供給手段
２２ ガラス層
３０ 制御装置
ＰＵｉ 堆積開始端[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a method for manufacturing a glass preform for an optical fiber.
[0002]
[Prior art]
As a conventional method and apparatus for manufacturing a glass preform for optical fibers, a reaction tube made of quartz is rotated, a raw material gas is supplied to the inside of the reaction tube, and the reaction tube is heated from the outside. A method in which a glass layer is deposited on a substrate by a so-called MCVD method is disclosed (for example, see Patent Document 1).
In the MCVD method disclosed in Patent Document 1, when the heating source is reciprocated in the axial direction outside the reaction tube, the downstream end is gradually moved to the upstream side. . This prevents damage to the reaction tube at the end of the deposited portion of the glass layer and reduces soot deposition.
[0003]
[Patent Document 1]
JP-A-6-271329 (page 5-7, FIG. 1)
[0004]
[Problems to be solved by the invention]
By the way, in the glass deposition by the MCVD method, as shown in FIG. 3, a difference in the amount of glass deposition occurs between the start side and the end side of the deposition, and when it is formed into a fiber, it causes a characteristic variation in the longitudinal direction. .
This is because, as shown in FIG. 4, in the reaction in which the glass layer 101 is generated inside the reaction tube 100, the amount of glass generated is small on the upstream side at the start of the deposition because the internal temperature is low, and then the deposition gradually proceeds. There is a time lag before progressing and reaching an equilibrium state. As a result, as shown in FIG. 4, the deposition amount of the glass layer 101 in the effective portion differs between the upstream side and the downstream side, and a difference occurs in the wall thickness of the reaction tube 100.
[0005]
Further, as shown in FIG. 5, as the glass layer 101 is deposited and the thickness of the reaction tube 100 is increased, the delay until the deposition of the glass layer 101 reaches equilibrium is also increased. That is, the delay time TL1 when the thickness is large is longer than the delay time TL0 when the thickness is small (TL0 <TL1). This is also a factor that causes a change in the characteristics in the longitudinal direction when the fiber is formed.
FIG. 5 shows a case where the thickness of the reaction tube 100 changes due to the deposition of the glass layer 101, and the surface temperature of the reaction tube 100 is set to the same temperature.
[0006]
An object of the present invention is to provide a method of manufacturing a glass preform for an optical fiber, which can reduce a variation in a characteristic in a longitudinal direction by making a thickness of a glass layer deposited inside a reaction tube uniform. is there.
[0007]
[Means for Solving the Problems]
In order to achieve the above-described object, a method for manufacturing a glass preform for an optical fiber according to the present invention includes supplying a raw material gas from an upstream side to a rotating reaction tube and heating a reaction source for heating the reaction tube from the outside. A method for producing a glass preform for an optical fiber in which a glass layer is deposited inside the reaction tube by moving from the upstream side to the downstream side, wherein the deposition start end is moved stepwise to the upstream side. .
[0008]
In the method for manufacturing a glass preform for an optical fiber thus configured, the reaction tube is rotated while supplying the raw material gas from the upstream side, and the heat source is reciprocated in the longitudinal direction of the reaction tube to heat the reaction tube. A glass layer is deposited inside. At this time, the upstream end of the movement range of the heat source, which is the deposition start end, is moved stepwise to the upstream side. As a result, the transient state from the deposition start end, which extends with the increase in the thickness of the reaction tube due to the deposition, until the deposition reaches an equilibrium state, is moved to the upstream side of the effective portion, and the glass base material to be manufactured is moved. The deposition amount of the glass layer in the effective portion is made uniform.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, an embodiment of a method and an apparatus for manufacturing a glass preform for an optical fiber according to the present invention will be described in detail with reference to the drawings. 1 is a front view of an apparatus for manufacturing a glass preform for an optical fiber according to the present invention, and FIG. 2 is a method for manufacturing a glass preform for an optical fiber according to the present invention and a glass layer in the glass preform manufactured by the manufacturing apparatus. FIG. 3 is a cross-sectional view showing a state of deposition of the metal.
[0010]
As shown in FIG. 1, an apparatus 10 for manufacturing a glass preform for an optical fiber includes columns 12, 12 at an upstream end (left end in FIG. 1) and a downstream end of an upper surface 11 a of a base 11, respectively. It is erected. At the upper ends of the columns 12, 12, a holding portion 13 for holding a reaction tube 20 made of quartz is rotatably provided. A pedestal 14, which is a heat source moving mechanism, is provided between the two columns 12, 12 on the upper surface 11 a of the base 11 so as to be reciprocally movable by a motor 15, and a heat source 17 is attached. The motor 15 is controlled by the control device 30.
[0011]
A position detector 16 is attached to the pedestal 14, and transmits the position of the pedestal 14 to the control device 30. As the position detector 16, a rotary encoder can be attached to the motor 15 to detect the position from the rotation speed of the motor 15. Alternatively, a linear scale may be provided on the base 11, and the position may be detected by a detector provided on the base 14.
[0012]
The control device 30 controls the motor 15 to reciprocate the pedestal 14 by controlling the motor 15, and the deposition start end PUi (see FIG. 2), which is the upstream end of the movement range of the heat source 17, corresponds to the number of reciprocations. It includes a reciprocating range commanding unit 32 that is set to move to the upstream in a stepwise manner, a comparing unit 33 that receives a position signal from the position detector 16 provided on the pedestal 14 and compares it with the set reciprocating range. ing.
[0013]
Next, a method for producing a glass preform for an optical fiber according to the present invention will be described. While rotating the reaction tube 20 held by the holding unit 13, the source gas supply unit 21 supplies a source gas such as silicon tetrachloride, boron trichloride, or the like into the reaction tube 20 from the upstream side. Then, the pedestal 14 is moved by the motor 15, and the heat source 17 is heated from the outside while reciprocating the heat source 17 from the upstream side to the downstream side along the longitudinal direction of the reaction tube 20. A glass layer 22 (see FIG. 2) is deposited.
[0014]
At this time, the reciprocating range command section 32 of the control device 30 sets the reciprocating range by gradually moving the deposition start end PUi to the upstream side. The comparison unit 33 compares the position signal from the position detector 16 with the reciprocating range, and the motor control unit 31 controls the motor 15 of the heat source moving mechanism to reciprocate the pedestal 14 so that the pedestal 14 falls within the reciprocating range. Let it.
[0015]
Therefore, as shown in FIG. 2, as the deposition start end PUi moves to the upstream side, the position where the deposition is balanced also moves to the upstream side. As described above with reference to FIG. 5, as the thickness of the reaction tube 20 increases due to the deposition of the glass layer 22, the time required for the deposition to reach equilibrium is absorbed. A uniform deposition of the glass layer 22 is always obtained.
In addition, since a non-effective portion generated on the upstream side of the effective portion becomes long, it is preferable to attach a dummy pipe to reduce waste of the reaction tube 20.
[0016]
Next, specific examples manufactured by the above-described method and apparatus for manufacturing a glass preform for optical fibers will be described.
Table 1 shows the thickness of the deposited glass layer 22 when the deposition start end PUi is manufactured by moving the deposition start end PUi to the upstream side according to the present invention, and the thickness of the deposited glass layer when the conventional deposition start end position is constant. The results of the comparison are shown.
The amount of movement of the deposition start end PUi in the present invention was moved by 50 mm to the upstream side every 20 reciprocations of the heat source 17. In addition, the temperature of the heat source 17, the flow rate of the source gas, and the like were kept constant.
[0017]
[Table 1]
Figure 2004345924
[0018]
In the conventional method, the difference between the thickness of the glass layer deposited on the downstream side and the thickness of the glass layer deposited on the upstream side is 0.019 mm when the number of deposition traverses (the number of reciprocations of the heat source) is 20, and then 40 mm. The difference in thickness increases almost in proportion to the number of times of traversing: 60 times, 80 times, 100 times. That is, in the effective portion, the thickness of the glass layer deposited on the downstream side is thick, and the thickness of the glass layer deposited on the upstream side is small, so that the deposition amount of the glass layer is not uniform in the longitudinal direction.
[0019]
On the other hand, in the present invention, the difference between the thickness of the glass layer 22 deposited on the downstream side and the thickness of the glass layer 22 deposited on the upstream side is not so different when the number of deposition traverses is 20 and 100. Absent. Therefore, when the number of deposition traverses is 100, according to the method for manufacturing a glass preform for an optical fiber of the present invention, the difference in thickness between the upstream side and the downstream side is about 8 minutes as compared with the conventional case. It can be seen that it has become smaller to 1. That is, in the present invention, it can be seen that the thickness of the glass layer 22 to be deposited is uniform in the longitudinal direction.
[0020]
As described above, according to the above-described method and apparatus for manufacturing a glass base material for an optical fiber, the upstream end of the movement range of the heat source 17, which is the deposition start end PUi, is moved stepwise to the upstream side, thereby causing a reaction by deposition. The transient state from the deposition start end PUi, which extends with the increase in the wall thickness of the pipe 20 until the deposition reaches an equilibrium state, is moved to the upstream side of the effective portion. Thereby, the deposition amount of the glass layer 22 in the effective portion can be made uniform, and variation in the characteristics in the longitudinal direction when the fiber is formed can be reduced.
[0021]
The method and apparatus for manufacturing a glass preform for an optical fiber of the present invention are not limited to the above-described embodiment, and appropriate modifications and improvements can be made.
For example, as the heat source moving mechanism in the above-described manufacturing apparatus 10, a type that is self-propelled by a motor 15 provided on a pedestal 14 is exemplified. In addition, a ball screw rotated by a motor is provided along a base 11 along a reaction tube 20. And a ball nut that is screwed into the ball screw and reciprocates along the ball screw may be attached to the base 14.
[0022]
【The invention's effect】
As described above, according to the method for manufacturing a glass preform for an optical fiber according to the present invention, the reaction tube is rotated while supplying the raw material gas from the upstream side, and the heat source is moved in the longitudinal direction of the reaction tube. Heat to deposit a glass layer inside the reaction tube. At this time, the upstream end of the movement range of the heat source, which is the deposition start end, is moved stepwise to the upstream side. As a result, the transition from the deposition start end, which is extended with the increase in the thickness of the reaction tube due to deposition, to the reaction becoming equilibrium, is moved to the upstream side of the effective portion, and the glass layer is deposited in the effective portion. The amount can be made uniform, and the variation in the characteristics in the longitudinal direction when the fiber is formed can be reduced.
[Brief description of the drawings]
FIG. 1 is a configuration diagram showing an embodiment of an apparatus for manufacturing a glass preform for an optical fiber according to the present invention.
FIG. 2 is a cross-sectional view illustrating a method of manufacturing a glass preform for an optical fiber according to the present invention and a thickness of a glass layer deposited inside a reaction tube by the manufacturing method.
FIG. 3 is a graph showing a transient state from a deposition start point, which is conventionally known, until the reaction becomes equilibrium.
FIG. 4 is a cross-sectional view showing the thickness of a glass layer deposited inside a reaction tube by a conventional method.
FIG. 5 is a graph showing the relationship between the thickness of a reaction tube and a transient state.
[Explanation of symbols]
10 Manufacturing apparatus for glass preform for optical fiber 15 Motor (heat source moving mechanism)
17 Heat source 20 Reaction tube 21 Source gas supply means 22 Glass layer 30 Control unit PUi Deposition start end

Claims (1)

回転する反応管の内部に上流側から原料ガスを供給し、前記反応管を外側から加熱する熱源を上流側から下流側へ移動させて前記反応管の内部にガラス層を堆積させる光ファイバ用ガラス母材の製造方法であって、
堆積開始端を段階的に上流側へ移動させることを特徴とする光ファイバ用ガラス母材の製造方法。Raw material gas is supplied from the upstream side to the inside of the rotating reaction tube, and a heat source for heating the reaction tube from the outside is moved from the upstream side to the downstream side to deposit a glass layer inside the reaction tube. A method of manufacturing a base material,
A method of manufacturing a glass preform for an optical fiber, comprising: moving a deposition start end stepwise to an upstream side.
JP2003146769A 2003-05-23 2003-05-23 Manufacturing method of glass preform for optical fiber Expired - Fee Related JP4203731B2 (en)

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