JP2947423B2 - Optical fiber preform refractive index distribution measurement method - Google Patents
Optical fiber preform refractive index distribution measurement methodInfo
- Publication number
- JP2947423B2 JP2947423B2 JP31199490A JP31199490A JP2947423B2 JP 2947423 B2 JP2947423 B2 JP 2947423B2 JP 31199490 A JP31199490 A JP 31199490A JP 31199490 A JP31199490 A JP 31199490A JP 2947423 B2 JP2947423 B2 JP 2947423B2
- Authority
- JP
- Japan
- Prior art keywords
- refractive index
- base material
- index distribution
- optical fiber
- starting
- 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 - Lifetime
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- Investigating Or Analysing Materials By Optical Means (AREA)
Description
【発明の詳細な説明】 [産業上の利用分野] この発明は、光ファイバ母材の屈折率分布測定方法に
関するものである。Description: TECHNICAL FIELD The present invention relates to a method for measuring the refractive index distribution of an optical fiber preform.
[従来の技術] (1)出発母材と完成母材について: 一般に、光ファイバ母材の製造に際しては、先ず第5
図のように、コア12およびクラッド14の一部を同時に形
成し(以下この段階のものを発母材10という)、その
後、不足している分のクラッド16を、外付け法あるいは
ジャケット法により付け足して完成する(以下これを完
成母材18という)。[Prior art] (1) Regarding starting preform and finished preform: Generally, when producing an optical fiber preform, first, a fifth preform is used.
As shown in the figure, a part of the core 12 and a part of the clad 14 are simultaneously formed (hereinafter, this stage is referred to as a base material 10), and then the insufficient clad 16 is removed by an external method or a jacket method. It is completed by adding (this is hereinafter referred to as completed base material 18).
その際、不足しているクラッド量を推定するために、
出発母材10を作製した段階で、その屈折率分布を測定
し、クラッド部14の屈折率を基準にして比屈折率差Δ1
を求め、それからクラッド不足分を推定していた。At that time, in order to estimate the insufficient cladding amount,
At the stage when the starting base material 10 was prepared, its refractive index distribution was measured, and the relative refractive index difference Δ1 was determined based on the refractive index of the cladding portion 14.
And then estimated the cladding shortage.
また同時に、この比屈折率差Δ1から種々の伝送特性
の推定も行っていた。At the same time, various transmission characteristics were estimated from the relative refractive index difference Δ1.
(2)屈折率分布の測定 屈折率分布の測定方法の一例を述べると、第6図のよ
うに、マッチングオイル20の中に浸した出発母材10に、
y軸上のyの位置Aにおいて、光軸22に平行な光ビーム
24を、x軸に対して垂直に入射する。(2) Measurement of Refractive Index Distribution An example of a method of measuring a refractive index distribution is as follows. As shown in FIG.
a light beam parallel to the optical axis 22 at a position A of y on the y axis
24 are incident perpendicular to the x-axis.
光ビーム24は、屈折角φで曲がり、レンズ26を透り、
その焦点免に設けた位置検出器28のB(光軸22からの距
離y′)に入る。The light beam 24 bends at the refraction angle φ, passes through the lens 26,
It enters B (the distance y 'from the optical axis 22) of the position detector 28 provided at the defocusing point.
このy′の値から、計算により、φが求められる。 From the value of y ′, φ is obtained by calculation.
光ビーム24の入射位置をy軸方向に少しずつ変化さ
せ、それに対応するy′を求めてゆくと、屈折角φの分
布が得られ、それから計算により、第5図の下段のよう
な屈折率分布が得られる。When the incident position of the light beam 24 is gradually changed in the y-axis direction and the corresponding y 'is obtained, the distribution of the refraction angle φ is obtained. From the calculation, the refractive index as shown in the lower part of FIG. A distribution is obtained.
この屈折率分布から、比屈折率差Δ1が求められる。 From this refractive index distribution, a relative refractive index difference Δ1 is obtained.
[発明が解決しようとする課題] 出発母材10において不足しているクラッドを付け足す
のに、通常、純粋石英を用いる。[Problems to be Solved by the Invention] Pure quartz is usually used to add the missing cladding in the starting base material 10.
したがって、完成母材のクラッド部の屈折率は石英の
屈折率と同じ値であり、完成母材18の比屈折率差Δ2
は、この値を基準にしている(第5図の右側)。Therefore, the refractive index of the clad portion of the completed base material is the same value as the refractive index of quartz, and the relative refractive index difference Δ2
Is based on this value (right side in FIG. 5).
ところが、出発母材10のクラッド部14には、脱水工程
で用いる成分(たとえば塩素系成分)などが残留し、石
英の屈折率と同じ値でない。However, components (eg, chlorine-based components) used in the dehydration step remain in the clad portion 14 of the starting base material 10, and do not have the same value as the refractive index of quartz.
そのため、比屈折率差の値が、出発母材と完成母材と
で異なり、出発母材で推定した伝送特性と完成母材の伝
送特性とが一致しない。Therefore, the value of the relative refractive index difference differs between the starting base material and the completed base material, and the transmission characteristics estimated for the starting base material and the transmission characteristics of the completed base material do not match.
[課題を解決するための手段] 第1図のように、付け足すクラッド(通常、純粋石
英)と同じ屈折率を持つ透明ガラス管30を、前記出発母
材10の外側に同軸状にかぶせておいて、屈折率分布の測
定を行う。[Means for Solving the Problems] As shown in FIG. 1, a transparent glass tube 30 having the same refractive index as the cladding (usually pure quartz) to be added is coaxially covered on the outside of the starting base material 10. Then, the refractive index distribution is measured.
[作用] 上記の測定により得られる屈折率分布における、透明
ガラス管30の部分とコア12の部分との屈折率の値から比
屈折率差Δ3を求めると(第4図参照)、その値は、完
成母材18の比屈折率差Δ2に等しい。[Operation] When the relative refractive index difference Δ3 is determined from the refractive index values of the transparent glass tube 30 and the core 12 in the refractive index distribution obtained by the above measurement (see FIG. 4), the value is , The relative refractive index difference Δ2 of the completed base material 18.
[その説明] 後で付け足すクラッドは、通常、純粋石英であるか
ら、透明ガラス管30としても、純粋石英管を用いる。[Description] Since a cladding to be added later is usually pure quartz, a pure quartz tube is used as the transparent glass tube 30 as well.
透明ガラス管30を出発母材10に対して同軸状に保つた
めに、たとえば第2図、第3図のように、ゴムリング32
を介在させる。In order to keep the transparent glass tube 30 coaxial with the starting base material 10, for example, as shown in FIGS.
Intervene.
第3図のように透明ガラス管30をかぶせた出発母材10
を、第1図のようにマッチングオイル20の中に浸し、た
とえば従来の第6図の場合同様に、軸方向に対して垂直
な光ビーム24を入射して、屈折率分布の測定を行う。Starting base material 10 covered with a transparent glass tube 30 as shown in FIG.
Is immersed in a matching oil 20 as shown in FIG. 1 and a refractive beam distribution is measured by injecting a light beam 24 perpendicular to the axial direction, for example, as in the case of the conventional FIG.
なお、そのとき、透明ガラス管30と出発母材10との間
にもマッチングオイル20が入るようにする。At this time, the matching oil 20 is also inserted between the transparent glass tube 30 and the starting base material 10.
上記の測定により得られる屈折率分布のプロファイル
を第4図の一番右に示す(出発母材および完成母材の屈
折率分布も、比較のために合わせ示した)。The profile of the refractive index distribution obtained by the above measurement is shown on the far right of FIG. 4 (the refractive index distributions of the starting base material and the finished base material are also shown for comparison).
この屈折率分布から、出発母材10の比屈折率差Δ1を
求めることができると同時に、透明ガラス管30の屈折率
に対する出発母材10の比屈折率差Δ3を求めることがで
きる。From this refractive index distribution, the relative refractive index difference Δ1 of the starting base material 10 can be determined, and at the same time, the relative refractive index difference Δ3 of the starting base material 10 with respect to the refractive index of the transparent glass tube 30 can be determined.
透明ガラス管30の屈折率は、後付けするクラッド16の
屈折率と同じにしてあるから、Δ3は、完成母材の比屈
折率差Δ2に等しい。Since the refractive index of the transparent glass tube 30 is the same as the refractive index of the cladding 16 to be added later, Δ3 is equal to the relative refractive index difference Δ2 of the completed base material.
[発明の効果] コアとクラッドとからなる出発母材に上に、不足して
いるクラッドを付け足して光ファイバ母材を製造する場
合に、前記出発母材を作製した段階で、当該出発母材
に、軸方向に対して垂直な光ビームを入射し、その出射
光を解析して屈折率分布を測定するに際して;付け足す
前記クラッドと同じ屈折率を持つ透明ガラス管を、前記
出発母材の外側に同軸状にかぶせておいて、前記測定を
行うようにしたので、出発母材の屈折率分布の測定時
に、完成母材の比屈折率差を同時に求めることができ
る。[Effects of the Invention] When an optical fiber preform is manufactured by adding a missing clad to a starting preform consisting of a core and a clad, the starting preform is prepared at the stage of producing the starting preform. In order to measure a refractive index distribution by analyzing a light beam perpendicular to the axial direction and analyzing the emitted light, a transparent glass tube having the same refractive index as the clad to be added is placed outside the starting base material. Since the above measurement is performed while coaxially covering the base material, the relative refractive index difference of the finished base material can be determined at the same time when the refractive index distribution of the starting base material is measured.
したがって、不足クラッド量の推定や伝送特性の推定
の精度が向上する。Therefore, the accuracy of the estimation of the insufficient cladding amount and the estimation of the transmission characteristics is improved.
第1〜4図は、本発明の実施例にかかるもので、第1図
は屈折率分布測定の説明図、 第2図は透明ガラス管30とゴムリング32を組み合わせた
状態の説明図、 第3図は出発母材10に透明ガラス管30をかぶせた状態の
説明図、 第4図は屈折率分布に、従来の出発母材10および完成母
材18の屈折率分布を併記した説明図、 第5図は出発母材10および完成母材18の屈折率分布の説
明図、 第6図は従来の出発母材10の屈折率分布測定の一例を示
す説明図。 10:出発母材、12:コア 14:クラッド 16:付け足したクラッド 18:完成母材 20:マッチングオイル 22:光軸、24:光ビーム 26:レンズ、28:位置検出器 30:透明ガラス管、32:ゴムリング1 to 4 relate to an embodiment of the present invention, FIG. 1 is an explanatory view of a refractive index distribution measurement, FIG. 2 is an explanatory view of a state where a transparent glass tube 30 and a rubber ring 32 are combined, FIG. 3 is an explanatory view showing a state in which a transparent glass tube 30 is covered on the starting base material 10, FIG. 4 is an explanatory view showing the refractive index distribution and the refractive index distributions of the conventional starting base material 10 and completed base material 18 together, FIG. 5 is an explanatory view of the refractive index distribution of the starting base material 10 and the finished base material 18, and FIG. 6 is an explanatory view showing an example of a conventional refractive index distribution measurement of the starting base material 10. 10: Starting material, 12: Core 14: Clad 16: Added cladding 18: Finished material 20: Matching oil 22: Optical axis, 24: Light beam 26: Lens, 28: Position detector 30: Transparent glass tube, 32: Rubber ring
Claims (1)
に、不足しているクラッドを付け足して光ファイバ母材
を製造する場合に、前記出発母材を作製した段階で、当
該出発母材に、軸方向に対して垂直な光ビームを入射
し、その出射光を解析して屈折率分布を測定するに際し
て、 付け足す前記クラッドと同じ屈折率を持つ透明ガラス管
を、前記出発母材の外側に同軸状にかぶせておいて、前
記測定を行う、光ファイバ母材の屈折率分布測定方法。An optical fiber preform is produced by adding a missing clad to a starting preform consisting of a core and a clad. Then, when a light beam perpendicular to the axial direction is incident, and the emitted light is analyzed to measure the refractive index distribution, a transparent glass tube having the same refractive index as the cladding to be added is placed outside the starting base material. A method for measuring the refractive index distribution of an optical fiber preform, wherein the measurement is carried out while coaxially covering the optical fiber.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP31199490A JP2947423B2 (en) | 1990-11-16 | 1990-11-16 | Optical fiber preform refractive index distribution measurement method |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP31199490A JP2947423B2 (en) | 1990-11-16 | 1990-11-16 | Optical fiber preform refractive index distribution measurement method |
Publications (2)
Publication Number | Publication Date |
---|---|
JPH04184134A JPH04184134A (en) | 1992-07-01 |
JP2947423B2 true JP2947423B2 (en) | 1999-09-13 |
Family
ID=18023929
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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JP31199490A Expired - Lifetime JP2947423B2 (en) | 1990-11-16 | 1990-11-16 | Optical fiber preform refractive index distribution measurement method |
Country Status (1)
Country | Link |
---|---|
JP (1) | JP2947423B2 (en) |
-
1990
- 1990-11-16 JP JP31199490A patent/JP2947423B2/en not_active Expired - Lifetime
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JPH04184134A (en) | 1992-07-01 |
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