JPH05286737A - Production of optical fiber preform - Google Patents
Production of optical fiber preformInfo
- Publication number
- JPH05286737A JPH05286737A JP4088640A JP8864092A JPH05286737A JP H05286737 A JPH05286737 A JP H05286737A JP 4088640 A JP4088640 A JP 4088640A JP 8864092 A JP8864092 A JP 8864092A JP H05286737 A JPH05286737 A JP H05286737A
- Authority
- JP
- Japan
- Prior art keywords
- temperature
- glass
- fiber preform
- optical fiber
- heat treatment
- 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
Landscapes
- Manufacture, Treatment Of Glass Fibers (AREA)
Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、光ファイバ母材の製造
方法に関し、特にそのまま光ファイバ母材とするか、光
ファイバ母材製造のための中間製品となる母材の製法に
関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an optical fiber preform, and more particularly to a method for producing an optical fiber preform as it is or an intermediate product for producing an optical fiber preform.
【０００２】[0002]
【従来の技術】光ファイバ母材の製造方法として、気相
合成法、例えば気相軸付法あるいは外付法により合成さ
れたガラス微粒子を電気炉にて高温加熱処理することに
より、透明ガラス化する方法がある。従来、透明ガラス
化は、常圧においてヘリウムガスあるいはハロゲンガス
を微量に含んだ不活性ガスの充満した雰囲気中で加熱処
理することにより行われてきた。これらの方法では、透
明化する際、ガラス微粒子堆積体の粒子間に閉じ込めら
れたガスが残留し、透明ガラス体内に気泡を生じる問題
がある。これに対し、近年、特開昭６３−２１０１０２
５号公報に記載されるような真空雰囲気あるいは減圧雰
囲気下にて透明化する方法が提案されている。この方法
では、雰囲気が減圧されるために、ガラス微粒子堆積体
中のガスが脱気され、ガラス体内に気泡が残留しないこ
とが期待される。2. Description of the Related Art As a method for producing an optical fiber preform, glass fine particles synthesized by a vapor phase synthesis method, for example, a vapor phase axis attaching method or an external attaching method are heated at a high temperature in an electric furnace to form a transparent glass. There is a way to do it. Conventionally, transparent vitrification has been performed by heat treatment in an atmosphere filled with an inert gas containing a slight amount of helium gas or halogen gas under normal pressure. In these methods, there is a problem that the gas trapped between the particles of the glass particle deposit body remains during the transparentization, and bubbles are generated in the transparent glass body. On the other hand, in recent years, JP-A-63-210102
A method of making transparent under a vacuum atmosphere or a reduced pressure atmosphere as described in Japanese Patent No. 5 has been proposed. In this method, since the atmosphere is depressurized, it is expected that the gas in the glass particulate deposit body is degassed and no bubbles remain in the glass body.
【０００３】[0003]
【発明が解決しようとする課題】従来、真空あるいは減
圧雰囲気で加熱処理する装置は、図２に示すような構成
となっている。すなわち、ガラス微粒子堆積体１の周囲
を囲む炉芯管２、この外側に加熱用ヒータ８が設置され
た均熱炉が、ヒートシールド９を挟んで真空容器１０の
中に入った構成となっている。真空容器１０内には、脱
気用配管６に接続された真空ポンプ７により減圧、真空
雰囲気となる構造となっており、この上端でヒータ温度
を上げることにより、炉芯管２内に挿入されているガラ
ス微粒子堆積体１が透明化される。Conventionally, an apparatus for heat treatment in a vacuum or reduced pressure atmosphere has a structure as shown in FIG. That is, the furnace core tube 2 surrounding the glass fine particle deposit body 1 and the soaking furnace in which the heater 8 for heating is installed outside the furnace core tube 2 are arranged inside the vacuum container 10 with the heat shield 9 interposed therebetween. There is. The vacuum vessel 10 has a structure in which a vacuum pump 7 connected to the degassing pipe 6 depressurizes and creates a vacuum atmosphere. By raising the heater temperature at the upper end of the vacuum vessel 10, the furnace core tube 2 is inserted. The deposited glass particle deposit 1 is made transparent.
【０００４】上記、加熱炉を用いて減圧、真空雰囲気
で、従来法により加熱処理一例として図６に示す温度条
件にて透明化温度（通常１５５０℃〜１６５０℃）まで
温度を上げ透明化したところ、期待に反し、気泡が残留
する場合が散見された。また、透明化したガラス物品の
外径が長手方向に均一とならず、図７に示す如く両端で
太く中間部で細くなるような形状となってしまった。こ
の方法で得られた加熱ロッドを用いて高品質なガラス物
品を製造するためには、気泡の残留を安定して減少ある
いは無くすことが必要であり、且つ仕上がった透明ガラ
ス物品を均一外径とすることが必要である。本発明はこ
のような要求を満足できるガラスファイバ母材の製造方
法の改良をその課題とするものである。[0006] When the temperature was raised to the clearing temperature (usually 1550 ° C to 1650 ° C) under the temperature condition shown in Fig. 6 as an example of the heat treatment by the conventional method using the above heating furnace under reduced pressure and vacuum atmosphere, the transparentization was performed. However, contrary to expectations, there were occasions when air bubbles remained. In addition, the outer diameter of the transparent glass article was not uniform in the longitudinal direction, and as shown in FIG. 7, the glass article had a shape in which both ends were thick and the middle part was thin. In order to produce a high quality glass article using the heating rod obtained by this method, it is necessary to stably reduce or eliminate residual air bubbles, and the finished transparent glass article has a uniform outer diameter. It is necessary to. An object of the present invention is to improve a method for manufacturing a glass fiber preform that can satisfy such requirements.
【０００５】[0005]
【課題を解決するための手段】上記課題を解決する本発
明は、気相合成法によりガラス微粒子堆積体を合成し、
該ガラス微粒子堆積体を真空あるいは減圧雰囲気中で加
熱処理することにより透明ガラス化して光ファイバ母材
を製造する方法において、該加熱処理が母材からのガス
を除去する第一の加熱工程と、前記第一の加熱工程より
高温にて透明ガラス化させる第二の加熱工程を含むこと
を特徴とする光ファイバ母材の製造方法を提供する。本
発明においては、上記第一の加熱工程は、９００〜１２
００℃の温度範囲で真空度が１０Ｐａ以下に到達するま
で当該加熱工程を継続することが特に好ましく、また、
上記第二の加熱工程は、１０Ｐａ以下の真空度におい
て、１５００〜１６００℃の温度を１分〜６０分間保持
することが特に好ましい。またさらに、上記加熱処理に
先立ち、予め上記ガラス微粒子堆積体を室温において２
０Ｐａ以下の真空度まで減圧処理しておくことも本発明
の特に好ましい実施態様として挙げられる。According to the present invention for solving the above-mentioned problems, a glass fine particle deposit is synthesized by a vapor phase synthesis method,
In the method for producing an optical fiber preform by vitrifying the glass fine particle deposit by heat treatment in a vacuum or a reduced pressure atmosphere, the first heating step in which the heat treatment removes gas from the preform, There is provided a method for producing an optical fiber preform, which includes a second heating step of making vitrified transparent at a higher temperature than the first heating step. In the present invention, the first heating step is 900 to 12
It is particularly preferable to continue the heating step until the degree of vacuum reaches 10 Pa or less in the temperature range of 00 ° C.
In the second heating step, it is particularly preferable to maintain the temperature of 1500 to 1600 ° C. for 1 to 60 minutes at a vacuum degree of 10 Pa or less. Furthermore, prior to the heat treatment, the glass particulate deposit is preliminarily dried at room temperature for 2 hours.
It is also mentioned as a particularly preferred embodiment of the present invention that the vacuum treatment is performed to a vacuum degree of 0 Pa or less.
【０００６】[0006]
【作用】上記課題を解決する手段として、本発明は気相
合成法によりガラス微粒子堆積体を合成し、該ガラス微
粒子堆積体を真空あるいは減圧雰囲気で加熱処理するこ
とにより、透明ガラス化して光ファイバ母材とする方法
において、９００℃〜１２００℃の温度範囲で母材から
脱ガスを行い、１０Ｐａまで減圧する第一ステップ（第
一の加熱工程）と、１５００℃〜１６００℃の温度で透
明ガラス化する第二ステップ（第二の加熱工程）の二段
階の熱処理を行なうことを特徴とする。ガラス微粒子堆
積体は加熱処理工程に入る前に室温で２０Ｐａ以下に減
圧処理を行っておくことが好ましい。加熱処理工程にお
いては、昇温速度も重要である。８００℃から第一ステ
ップの温度までの昇温速度は２℃／分〜１０℃／分以
下、第一ステップから第二ステップの温度範囲では１℃
／分〜４℃／分の昇温速度が好ましい。第一ステップか
ら第二ステップへの昇温過程においては、途中１回以
上、昇温速度を変化させることも可能であるが、変化後
の速度は変化前よりも遅くすることが必要である。さら
に、ガラス微粒子堆積体を加熱する発熱体は上下方向に
多段に分割され、下部の温度はその上部の温度と等しい
かそれ以下に制御することが好ましい。As a means for solving the above problems, the present invention synthesizes a glass particulate deposit by a gas phase synthesis method, and heat-treats the glass particulate deposit in a vacuum or a reduced pressure atmosphere to form a transparent vitrified optical fiber. In the method of using the base material, the first step (first heating step) of degassing the base material in the temperature range of 900 ° C to 1200 ° C and reducing the pressure to 10 Pa, and the transparent glass at a temperature of 1500 ° C to 1600 ° C It is characterized by performing a two-step heat treatment of a second step (second heating step) of forming. It is preferable that the glass particulate deposit is subjected to a pressure reduction treatment at room temperature to 20 Pa or less before entering the heat treatment step. In the heat treatment step, the temperature rising rate is also important. The temperature rising rate from 800 ° C to the temperature of the first step is 2 ° C / min to 10 ° C / min or less, and 1 ° C in the temperature range of the first step to the second step.
A heating rate of from 4 to 4 ° C./min is preferable. In the temperature rising process from the first step to the second step, it is possible to change the temperature rising rate once or more on the way, but it is necessary that the speed after the change is slower than that before the change. Further, it is preferable that the heating element for heating the glass particulate deposit is divided into a plurality of stages in the vertical direction, and the temperature of the lower part is controlled to be equal to or lower than the temperature of the upper part.
【０００７】本発明者らは、ガラス微粒子堆積体を減圧
雰囲気下で熱処理を行い、真空度とガラス微粒子堆積体
のカサ密度の変化を調べた。図３に示すごとく、９００
℃から１２００℃の範囲でガラス微粒子堆積体からの脱
ガスにより真空度が悪化している。ガラス微粒子堆積体
のカサ密度は、１２００℃から高くなり、１５５０℃で
透明ガラス化している。次に、本発明の目的とするガラ
スロッドの外周に気相合成法でガラス微粒子を堆積させ
た複合堆積体を用いて実験を行った。該複合堆積体を１
２００℃の温度において減圧処理を行い、その後さらに
１５５０℃に昇温し、透明ガラス化させるプロセスにお
いて、１２００℃での到達真空度と透明ガラス体内の気
泡の数との相関を調べた。結果を図４に示すが、１０Ｐ
ａ以下まで減圧した後、透明ガラス化すれば気泡は殆ど
生じないが、１０Ｐａに達する以前に昇温し透明ガラス
化した場合、気泡の数は急激に増大する。この気泡は主
として、ガラス微粒子が堆積しているガラスロッドの周
囲に生じ、数が少ない場合は、微小な泡として確認でき
るが、数が多数の場合、白く不透明に見える。従って、
ガラス微粒子堆積体からの脱ガスの最も多い温度範囲、
すなわち、図３の実験結果が示す９００℃から１２００
℃の範囲において、１０Ｐａ以下まで減圧した後、昇温
し、透明ガラス化することが、気泡のない透明ガラス体
を得るのに重要である。The inventors of the present invention conducted a heat treatment on the glass particulate deposit body in a reduced pressure atmosphere, and investigated changes in the degree of vacuum and the bulk density of the glass particulate deposit body. As shown in FIG. 3, 900
The degree of vacuum is deteriorated by degassing from the glass particulate deposit in the range of ℃ to 1200 ℃. The bulk density of the glass particle deposit increases from 1200 ° C. and becomes vitrified at 1550 ° C. Next, an experiment was conducted using a composite deposit body in which glass particles were deposited on the outer circumference of a glass rod, which is the object of the present invention, by a vapor phase synthesis method. 1 for the composite deposit
In the process of performing a depressurization treatment at a temperature of 200 ° C. and then further raising the temperature to 1550 ° C. to make it into a transparent glass, the correlation between the ultimate vacuum at 1200 ° C. and the number of bubbles in the transparent glass body was examined. The result is shown in FIG.
After the pressure is reduced to a or less, if the material becomes transparent vitrified, almost no bubbles are generated. However, if the temperature is raised to become transparent vitrification before reaching 10 Pa, the number of bubbles rapidly increases. The bubbles mainly occur around the glass rod on which the glass particles are deposited, and when the number is small, they can be confirmed as minute bubbles, but when the number is large, they appear white and opaque. Therefore,
The temperature range with the most outgassing from the glass particulate deposits,
That is, the experimental result of FIG.
In the range of 0 ° C., it is important to reduce the pressure to 10 Pa or less and then raise the temperature to form a transparent glass, in order to obtain a transparent glass body having no bubbles.
【０００８】光ファイバ母材の製造において、気泡のな
いことと同様に重要なのが、外径が均一である点であ
る。図５に示す如く、本発明者らは、第一ステップから
第二ステップへの昇温速度が外径差（下端径−中央径）
と強い相関関係があることを見いだした。この温度範囲
では、図５の実験結果に示されるように、ガラス微粒子
堆積体が急激に収縮する。そのため、下端部は加熱表面
積が大きいため、中央部と比較して加熱されやすく、収
縮し易い。そのため、下端部は中央部より太径化する。
こうして生ずる外径差に対しては、全体に渡って温度差
を小さくし、徐々に収縮させることが必要である。光フ
ァイバ母材として用いるためには、外径差を６ｍｍ程度
に抑える必要があるが、そのための適正な昇温速度は、
図５より１℃／分から４℃／分の間であることがわか
る。さらに、透明化温度域である１５００〜１６００℃
においては、必要以上長くガラス微粒子堆積体を加熱す
ると、ガラスが軟化しやすく、自重により垂れ下がる。
そのため、最小限の加熱で充分である。最小限の加熱時
間は、堆積体の外径やカサ密度に依存し、１分以上６０
分以内が望ましい。また、下端部の太径化を抑えるに
は、下端部の温度を下げることも有効であり、図１に示
すように加熱に用いる発熱体として上下方向に多段に分
割し、下部の温度を上部の温度以下にすることも可能で
ある。図１の場合にはヒータ３、４、５と３段に分割さ
れている。In the production of the optical fiber preform, as important as the absence of bubbles is that the outer diameter is uniform. As shown in FIG. 5, the present inventors have found that the temperature rising rate from the first step to the second step has an outer diameter difference (lower end diameter-center diameter).
I found a strong correlation with. In this temperature range, as shown in the experimental result of FIG. 5, the glass particulate deposits rapidly contract. Therefore, since the lower end portion has a large heating surface area, it is more likely to be heated and contract than the central portion. Therefore, the lower end has a larger diameter than the central part.
With respect to the difference in outer diameter that occurs in this way, it is necessary to reduce the temperature difference throughout and to gradually shrink the temperature difference. In order to use it as an optical fiber preform, it is necessary to suppress the difference in outer diameter to about 6 mm.
From FIG. 5, it can be seen that it is between 1 ° C./min and 4 ° C./min. Furthermore, the transparentization temperature range of 1500 to 1600 ° C
In (1), if the glass particulate deposit is heated for a longer period than necessary, the glass is likely to soften and sags due to its own weight.
Therefore, minimal heating is sufficient. The minimum heating time depends on the outer diameter of the sediment and the bulk density, and is 1 minute or more 60
Within minutes is desirable. Further, in order to suppress the increase in the diameter of the lower end portion, it is effective to lower the temperature of the lower end portion, and as shown in FIG. It is also possible to set the temperature to or below. In the case of FIG. 1, it is divided into three heaters 3, 4, and 5.
【０００９】一方、室温から第一ステップへの挿入過程
に注目すると、予め室温でガラス微粒子堆積体を２０Ｐ
ａ以下の真空度まで減圧しておくことが、加熱炉の保守
という目的で重要である。ガラス微粒子堆積体には水分
や塩酸などが多く含まれているからである。また、８０
０℃以下の温度ではガラス微粒子堆積体は何ら変化しな
いが、８００℃から第一ステップへの昇温過程には注意
が必要である。この温度域で急激に加熱すると、堆積体
内部のガスが急速に放出され、堆積体が割れる原因とな
る。しかし、必要以上に昇温速度を下げることは生産性
を下げることになり、望ましくなく、種々の検討によ
り、２℃／分〜８℃／分の間が適当である。On the other hand, paying attention to the insertion process from room temperature to the first step, 20 P of glass particle deposit was previously prepared at room temperature.
It is important to reduce the pressure to a vacuum level of a or less for the purpose of maintaining the heating furnace. This is because the glass particle deposit contains a large amount of water, hydrochloric acid and the like. Also, 80
The glass particulate deposit does not change at a temperature of 0 ° C. or lower, but caution is required in the temperature rising process from 800 ° C. to the first step. When heated rapidly in this temperature range, the gas inside the deposit is rapidly released, which causes the deposit to crack. However, lowering the temperature rising rate more than necessary lowers the productivity, which is not desirable, and various studies have made it suitable to be between 2 ° C / min and 8 ° C / min.
【００１０】[0010]
【実施例】以下に実施例により本発明を具体的に説明す
るが、本発明はこれに限定されるものではない。 実施例１ ＶＡＤ法で合成した純ＳｉＯ2 からなるガラス微粒子堆
積体を本発明に従い透明化した。ガラス微粒子堆積体の
寸法は、φ１６０ｍｍ×７００ｍｍのものを用いた。こ
の母材を室温で２０Ｐａに減圧した後、図１に示す炉内
に挿入し、１０００℃まで４℃／分で昇温した。このと
き、炉内圧は１８Ｐａであったが、一時間保持したとこ
ろ、５Ｐａに達したので、昇温速度２℃／分で１５５０
℃まで昇温した。ただし、炉の発熱体は３分割されてお
り、最下部のみ１５００℃までの昇温に止めた。この昇
温中、炉内圧はほぼ５Ｐａで一定であった。最高温に達
した後５分間保持し、降温した。この結果、得られたガ
ラス体は全長にわたり気泡は見られず良好な透明体であ
った。外径は全長にわたってφ７０ｍｍ±０．３ｍｍと
非常に均一なものが得られた。EXAMPLES The present invention will now be specifically described with reference to examples, but the present invention is not limited thereto. Example 1 A glass particle deposit made of pure SiO 2 synthesized by the VAD method was made transparent according to the present invention. The glass fine particle deposit had a size of 160 mm × 700 mm. After depressurizing this base material to 20 Pa at room temperature, it was inserted into the furnace shown in FIG. 1 and heated up to 1000 ° C. at 4 ° C./min. At this time, the internal pressure of the furnace was 18 Pa, but when it was held for 1 hour, it reached 5 Pa. Therefore, the temperature rise rate was 2550 ° C./min.
The temperature was raised to ° C. However, the heating element of the furnace was divided into three parts, and only the lowermost part was heated to 1500 ° C. During this temperature increase, the furnace pressure was constant at approximately 5 Pa. After reaching the maximum temperature, the temperature was maintained for 5 minutes and then lowered. As a result, the obtained glass body was a good transparent body with no bubbles observed over the entire length. The outer diameter was φ70 mm ± 0.3 mm, which was very uniform over the entire length.
【００１１】比較例１ 実施例１と同様にＶＡＤ法で合成したガラス微粒子堆積
体を、図２に示す構成で、炉内圧力を２０Ｐａに減圧
し、温度を８℃／分で昇温し、１６００℃で３０分間保
持し、次に冷却後、炉から取り出した。この結果、直径
０．１ｍｍ以下の微小気泡が全長にわたり見られ、外径
は中央部がφ６５ｍｍと細く、下部がφ７３ｍｍと太く
変形していた。Comparative Example 1 A glass fine particle deposited body synthesized by the VAD method in the same manner as in Example 1 was configured as shown in FIG. 2 to reduce the furnace pressure to 20 Pa and raise the temperature at 8 ° C./min. Hold at 1600 ° C. for 30 minutes, then cool and remove from furnace. As a result, minute bubbles having a diameter of 0.1 mm or less were seen over the entire length, and the outer diameter was deformed to be thin at the central portion of φ65 mm and thick at the lower portion of φ73 mm.
【００１２】実施例２ 実施例１と同様にＶＡＤ法で合成したガラス微粒子堆積
体を用いた。この母材を室温で２０Ｐａに減圧した後、
図１に示す炉内に挿入した。炉内は予め８００℃に昇温
してある。第一ステップの温度を１１００℃とし、８０
０℃から３℃／分の昇温速度で昇温した。このとき炉内
圧は２０Ｐａであった。１時間保持したところ、５Ｐａ
まで達したので、第二ステップへ昇温を開始した。第２
ステップの温度は１５５０℃とした。昇温過程は、まず
１１００℃から１４００℃へ３℃／分で昇温した後、１
４００℃から１５５０℃へ２℃／分で昇温した。炉の発
熱体は３分割されており、最下部のみ１５２０℃で止め
た。最高温に達した後、３分間保持し、降温した。この
加熱過程中、炉内圧は５Ｐａで一定であった。この結
果、得られたガラス体は全長にわたり気泡が見られず、
透明な良好体であった。外径は全長にわたってφ６８ｍ
ｍ±０．３ｍｍと均一であった。Example 2 As in Example 1, a glass particle deposit prepared by the VAD method was used. After depressurizing this base material to 20 Pa at room temperature,
It was inserted into the furnace shown in FIG. The temperature inside the furnace has been raised to 800 ° C. in advance. The temperature of the first step is set to 1100 ° C and 80
The temperature was raised from 0 ° C at a heating rate of 3 ° C / min. At this time, the furnace pressure was 20 Pa. Hold for 1 hour, 5Pa
Since the temperature reached the above, the temperature rise was started in the second step. Second
The step temperature was 1550 ° C. In the temperature raising process, first, the temperature was raised from 1100 ° C. to 1400 ° C. at 3 ° C./minute, and then 1
The temperature was raised from 400 ° C to 1550 ° C at 2 ° C / min. The heating element of the furnace was divided into three parts, and only the lowermost part was stopped at 1520 ° C. After reaching the maximum temperature, the temperature was maintained for 3 minutes and then lowered. During this heating process, the pressure inside the furnace was constant at 5 Pa. As a result, the obtained glass body does not show bubbles over the entire length,
It was a transparent good body. Outer diameter is φ68m over the entire length
It was uniform with m ± 0.3 mm.
【００１３】[0013]
【発明の効果】以上説明したように、本発明によれば、
ガラス微粒子堆積体内に存在するガスを充分に除去する
条件で製造するため、透明化後のガラス内に気泡の残留
がなく、また、ガラス微粒子堆積体の収縮が進行する温
度域での昇温速度を限定することによりガラス径の均一
なガラス体を得ることができる。As described above, according to the present invention,
Since it is manufactured under the condition that the gas existing in the glass particulate deposit is sufficiently removed, there are no bubbles remaining in the glass after clearing, and the temperature rising rate in the temperature range where the shrinkage of the glass particulate deposit progresses. By limiting the above, a glass body having a uniform glass diameter can be obtained.
【図１】 本発明の一実施態様である分割された発熱体
を有する加熱炉を用いる製法を概略説明する図である。FIG. 1 is a diagram schematically illustrating a manufacturing method using a heating furnace having divided heating elements, which is an embodiment of the present invention.
【図２】 本発明または従来法で用いる加熱炉を概略説
明する図である。FIG. 2 is a diagram schematically illustrating a heating furnace used in the present invention or a conventional method.
【図３】 減圧雰囲気下での熱処理における、真空度
（Ｐａ）とガラス微粒子堆積体のカサ密度（ｇ／ｃ
ｍ3 ）の変化を示すグラフ図である。FIG. 3 shows the degree of vacuum (Pa) and the bulk density (g / c) of the glass particle deposit in a heat treatment under a reduced pressure atmosphere.
m 3) is a graph showing changes in the.
【図４】 １２００℃での到達真空度と透明ガラス体内
の気泡の数の相関関係を示すグラフ図である。FIG. 4 is a graph showing the correlation between the ultimate vacuum at 1200 ° C. and the number of bubbles in the transparent glass body.
【図５】 第一ステップから第二ステップへの昇温速度
と外径差との相関関係を示すグラフ図である。FIG. 5 is a graph showing the correlation between the temperature rising rate from the first step to the second step and the outer diameter difference.
【図６】 従来の加熱処理の温度条件を示すグラフ図で
ある。FIG. 6 is a graph showing temperature conditions of conventional heat treatment.
【図７】 従来法により製造された外径差のあるガラス
物品の形状を示す説明図である。FIG. 7 is an explanatory view showing a shape of a glass article having a difference in outer diameter manufactured by a conventional method.
１ ガラス微粒子堆積体 ２ 炉芯管 ３ ヒータ ４ ヒータ ５ ヒータ ６ 脱気用配管 ７ 真空ポンプ ８ ヒータ ９ ヒートシールド １０ 真空容器 1 Glass Fine Particle Deposit 2 Furnace Core Tube 3 Heater 4 Heater 5 Heater 6 Degassing Pipe 7 Vacuum Pump 8 Heater 9 Heat Shield 10 Vacuum Container
Claims (8)
合成し、該ガラス微粒子堆積体を真空あるいは減圧雰囲
気中で加熱処理することにより透明ガラス化して光ファ
イバ母材を製造する方法において、該加熱処理が母材か
らのガスを除去する第一の加熱工程と、前記第一の加熱
工程より高温にて透明ガラス化させる第二の加熱工程を
含むことを特徴とする光ファイバ母材の製造方法。1. A method for producing an optical fiber preform by synthesizing a glass fine particle deposit by a vapor phase synthesis method and heat-treating the glass fine particle deposit to obtain a transparent vitrified glass by heating the glass fine particle deposit. Manufacturing of an optical fiber preform characterized in that the heat treatment includes a first heating step of removing gas from the preform, and a second heating step of vitrifying into transparent glass at a higher temperature than the first heating step. Method.
０℃の温度範囲で真空度が１０Ｐａ以下に到達するまで
当該加熱工程を継続す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 first heating step is 900-120.
The method for producing an optical fiber preform according to claim 1, wherein the heating step is continued until the degree of vacuum reaches 10 Pa or less in a temperature range of 0 ° C.
真空度において、１５００〜１６００℃の温度を１分〜
６０分間保持することを特徴とする請求項１又は請求項
２記載の光ファイバ母材の製造方法。3. The second heating step is performed at a temperature of 1500 to 1600 ° C. for 1 minute to at a vacuum degree of 10 Pa or less.
Holding for 60 minutes, The manufacturing method of the optical fiber preform of Claim 1 or Claim 2 characterized by the above-mentioned.
微粒子堆積体を室温において２０Ｐａ以下の真空度まで
減圧処理しておくことを特徴とする請求項１乃至請求項
３のいずれかに記載の光ファイバ母材の製造方法。4. The light according to any one of claims 1 to 3, wherein prior to the heat treatment, the glass particulate deposit is subjected to a pressure reduction treatment at room temperature to a vacuum degree of 20 Pa or less. Manufacturing method of fiber preform.
一の加熱処理工程の温度まで、２．０℃／分〜１０℃／
分の速度で昇温することを特徴とする請求項１乃至請求
項４のいずれかに記載の光ファイバ母材の製造方法。5. In the above heat treatment, from 800 ° C. to the temperature of the first heat treatment step, 2.0 ° C./minute to 10 ° C./minute
The method for producing an optical fiber preform according to claim 1, wherein the temperature is raised at a rate of a minute.
二の加熱処理工程の温度まで、１．０℃／分〜４℃／分
の速度で昇温し、且つ昇温過程中に一回以上昇温速度を
変化させた場合には変化後の昇温速度が変化前の昇温速
度以下であるように熱処理することを特徴とする請求項
１乃至請求項５のいずれかに記載の光ファイバ母材の製
造方法。6. The temperature is raised from the temperature of the first heat treatment step to the temperature of the second heat treatment step at a rate of 1.0 ° C./min to 4 ° C./min, and the temperature is raised during the temperature raising process. The heat treatment is performed such that when the temperature rising rate is changed more than once, the temperature rising rate after the change is equal to or lower than the temperature rising rate before the change. Manufacturing method of optical fiber preform.
発熱体は、上下方向に多段に分割されてそれぞれ独立に
温度を制御し、且つ下部の発熱体の温度が上部の発熱体
の温度以下になるように設定されることを特徴とする請
求項１乃至請求項６のいずれかに記載のガラスファイバ
母材の製造方法。7. The heating element for heat-treating the glass particle deposit is vertically divided into a plurality of stages to control the temperature independently of each other, and the temperature of the lower heating element is controlled to be equal to or lower than the temperature of the upper heating element. The method for producing a glass fiber preform according to any one of claims 1 to 6, wherein the glass fiber preform is set as follows.
も外周部で屈折率の低い少なくとも二重の導波路構造を
持つガラスロッドの外周に、気相合成法によりガラス微
粒子を体積させた複合体であることを特徴とする請求項
１乃至請求項７のいずれかに記載のガラスファイバ母材
の製造方法。8. A composite in which the glass fine particle deposit is made by volumeifying glass fine particles on the outer periphery of a glass rod having at least a double waveguide structure having a lower refractive index in the outer peripheral portion than in the central portion by a vapor phase synthesis method. It is a body, The manufacturing method of the glass fiber preform in any one of Claim 1 thru | or 7.
Priority Applications (6)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8864092A JP2985493B2 (en) | 1992-04-09 | 1992-04-09 | Manufacturing method of optical fiber preform |
| AU19688/92A AU653411B2 (en) | 1991-07-19 | 1992-07-15 | Method for producing glass preform for optical fiber |
| DE69209174T DE69209174T3 (en) | 1991-07-19 | 1992-07-16 | Process for making an optical fiber preform |
| EP92112148A EP0523692B2 (en) | 1991-07-19 | 1992-07-16 | Method for producing glass preform for optical fiber |
| US07/913,965 US5330548A (en) | 1991-07-19 | 1992-07-17 | Method for producing glass preform for optical fiber |
| KR1019920012835A KR940011118B1 (en) | 1991-07-19 | 1992-07-18 | Method of producing glass preform for optical fiber |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP8864092A JP2985493B2 (en) | 1992-04-09 | 1992-04-09 | Manufacturing method of optical fiber preform |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH05286737A true JPH05286737A (en) | 1993-11-02 |
| JP2985493B2 JP2985493B2 (en) | 1999-11-29 |
Family
ID=13948422
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP8864092A Expired - Lifetime JP2985493B2 (en) | 1991-07-19 | 1992-04-09 | Manufacturing method of optical fiber preform |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2985493B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008506626A (en) * | 2004-07-20 | 2008-03-06 | ヘレウス・テネボ・ゲゼルシャフト・ミット・ベシュレンクテル・ハフツング | Method and apparatus for the production of hollow cylinders made of quartz glass |
-
1992
- 1992-04-09 JP JP8864092A patent/JP2985493B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2008506626A (en) * | 2004-07-20 | 2008-03-06 | ヘレウス・テネボ・ゲゼルシャフト・ミット・ベシュレンクテル・ハフツング | Method and apparatus for the production of hollow cylinders made of quartz glass |
Also Published As
| Publication number | Publication date |
|---|---|
| JP2985493B2 (en) | 1999-11-29 |
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