JPH0617850B2 - Method of measuring refractive index of preform - Google Patents
Method of measuring refractive index of preformInfo
- Publication number
- JPH0617850B2 JPH0617850B2 JP10917485A JP10917485A JPH0617850B2 JP H0617850 B2 JPH0617850 B2 JP H0617850B2 JP 10917485 A JP10917485 A JP 10917485A JP 10917485 A JP10917485 A JP 10917485A JP H0617850 B2 JPH0617850 B2 JP H0617850B2
- Authority
- JP
- Japan
- Prior art keywords
- refractive index
- preform
- sheath
- liquid
- refractive
- 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
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
- G01N21/412—Index profiling of optical fibres
Landscapes
- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- 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） 本発明は光ファイバーのプリフォームの屈折率測定方法
に関し、より詳細にはプリフォームアナライザーを用い
た屈折率測定方法に関する。Description: TECHNICAL FIELD The present invention relates to a method of measuring a refractive index of an optical fiber preform, and more particularly to a method of measuring a refractive index using a preform analyzer.
（従来の技術） 従来、プリフォームの屈折率分布を非破壊的に測定する
一方法としてプリフォームアナライザーを用いた方法は
公知である。該方法は、第４図に示すごとく、測定され
るべきプリフォーム１のまわりに異種媒体間の損失の少
ない光ビーム接続を目的とした屈折液（或はマッチング
液）３を充満及び保持する透明パイプ状のセル５をパッ
キン７を用いて被せ、該セルの一側に設けた光源９より
光ビームをプリフォーム１にその長軸に対し直角方向に
入射させ、これら屈折液３およびプリフォーム１を透過
した光ビームを反対側に設けたレンズ11に集光してこれ
をＯ／Ｅ変換素子を含むディテクター13にて検出するよ
うにしたもので、光源９からの光ビームを第４図に示す
方向でプリフォーム１を横断するように走査せしめると
ディテクター13には屈折率の異なる各層を通過する度毎
に光路が変化することによる光強度分布が得られ、これ
を演算処理することにより第５図に示すごときプリフォ
ームの断面に沿った屈折率分布曲線が得られる。なお、
第５図においてａ，ｂはそれぞれコアＡおよびクラッド
Ｂに対応する屈折率を示す。(Prior Art) Conventionally, a method using a preform analyzer is known as one method for nondestructively measuring the refractive index distribution of a preform. As shown in FIG. 4, the method is a transparent method for filling and holding a refracting liquid (or matching liquid) 3 around a preform 1 to be measured for the purpose of connecting a light beam with little loss between different media. The pipe-shaped cell 5 is covered with a packing 7, and a light beam from a light source 9 provided on one side of the cell is made incident on the preform 1 in a direction perpendicular to the major axis thereof. The light beam that has passed through is condensed on a lens 11 provided on the opposite side and detected by a detector 13 including an O / E conversion element. The light beam from the light source 9 is shown in FIG. When scanning is performed so as to traverse the preform 1 in the direction shown, a light intensity distribution is obtained in the detector 13 by changing the optical path each time it passes through each layer having a different refractive index. Figure 5 Refractive index distribution curve along a cross section of the preform such showing is obtained. In addition,
In FIG. 5, a and b indicate the refractive indexes corresponding to the core A and the clad B, respectively.
（発明が解決しようとする問題点） 上記方法で求められる屈折率分布曲線は屈折率の絶対値
を示すものではなく、各層の屈折率相互間の相対関係を
示すものである。それ故、プリフォーム内の未知の屈折
率の絶対値を求めるには屈折率の基準となるべきものが
必要である。第５図において、クラッド層Ｂが純石英よ
りなる場合は、純石英の屈折率を基準としてコアＡの屈
折率を求めることができるが、実際にはクラッド層にド
ーパント剤を含むことが多く基準とすることはできな
い。このため、従来方法では屈折率の基準として検体と
なるプリフォームの周囲に充満される屈折液のもつ屈折
率を基準としていた。しかしながら、屈折液は液状であ
るため異物の混入により屈折率が変化する可能性があ
り、また外界の物理的、化学的変化による影響を受け易
い（例えば液温の変化によって屈折率が変化し易い）欠
点がある。このため屈折率のごく僅か異なる、例えば屈
折率比が、 100分の数パーセントの測定に対しては満足
できる測定精度を得ることは極めて困難であった。(Problems to be Solved by the Invention) The refractive index distribution curve obtained by the above method does not show the absolute value of the refractive index, but shows the relative relationship between the refractive indexes of the layers. Therefore, in order to obtain the absolute value of the unknown refractive index in the preform, what is to be the reference of the refractive index is necessary. In FIG. 5, when the cladding layer B is made of pure quartz, the refractive index of the core A can be obtained by using the refractive index of pure quartz as a reference, but in practice, the cladding layer often contains a dopant agent. Can not be. Therefore, in the conventional method, the refractive index of the refraction liquid filled around the preform as the sample is used as the reference of the refractive index. However, since the refractive liquid is a liquid, the refractive index may change due to the inclusion of foreign matter, and is easily affected by the physical and chemical changes in the external environment (for example, the refractive index changes easily due to changes in the liquid temperature). There is a drawback. For this reason, it was extremely difficult to obtain a satisfactory measurement accuracy for a measurement in which the refractive index is slightly different, for example, the refractive index ratio is several hundredths of a percent.
（問題点を解決するための手段） 本発明は上記従来の欠点を除去すべくなされたもので、
このため本発明は内部に純石英層を含まないプリフォー
ムにその長軸に対し直角方向に光ビームを当てて内部の
屈折率分布をプリフォームアナライザーにて測定する
に、該プリフォームのまわりに屈折液を介して既知屈折
率の透明のさや状物体を同心状にかぶせ、さらにその外
側を屈折液にて覆い、該プリフォームアナライザーの屈
折率線図上におけるさや状物体の屈折率レベルを基準と
してプリフォームの屈折率を求めることを特徴とする。(Means for Solving Problems) The present invention has been made to eliminate the above-mentioned conventional drawbacks.
Therefore, according to the present invention, a preform containing no pure quartz layer inside is irradiated with a light beam in a direction perpendicular to its long axis to measure the internal refractive index distribution with a preform analyzer. A transparent sheath with a known refractive index is concentrically covered with a refractive liquid, and the outside is covered with a refractive liquid, and the refractive index level of the sheath is used as a reference on the refractive index diagram of the preform analyzer. Is characterized in that the refractive index of the preform is obtained.
（作 用） 屈折率分布曲線上に既知の屈折率基準レベルが得られる
のでこれを基準としてプリフォーム各部の屈折率の絶対
値を求めることが容易であり、しかも基準レベルを与え
るさや状物体は異物混入のおそれがなくかつ外界の物理
的、化学的、化学的変化による影響を受けにくいので安
定かつ精度より測定を行うことができる。(Operation) Since a known refractive index reference level can be obtained on the refractive index distribution curve, it is easy to find the absolute value of the refractive index of each part of the preform with this as a reference. Since there is no risk of contamination by foreign matter and it is unlikely to be affected by physical, chemical or chemical changes in the external environment, stable and accurate measurement can be performed.
（実施例） 以下、本発明の内容を実施例に即して説明する。(Examples) The contents of the present invention will be described below with reference to Examples.
第１図は本発明方法を実施するための装置構成例を示す
もので、第４図と同一参照番号は同一構成部品を示す。
本実施例においては、検体となるプリフォーム１まわり
に屈折液３を充満保持せる純石英パイプ15を該プリフォ
ームと同心状に着脱自在に取付け、この純石英パイプ15
まわりにさらに屈折液３を充満保持させるセル５を着脱
自在に取付けてある。なお、17は屈折液３の洩れを防止
するパッキンである。FIG. 1 shows an example of the apparatus configuration for carrying out the method of the present invention, and the same reference numerals as those in FIG. 4 indicate the same components.
In the present embodiment, a pure quartz pipe 15 that holds the refraction liquid 3 is filled around the preform 1 as a sample so as to be concentrically and detachably attached concentrically with the preform.
Further, a cell 5 for holding the refraction liquid 3 in a full state is detachably attached around the cell 5. Reference numeral 17 is a packing that prevents the refraction liquid 3 from leaking.
このようにして、光源９からの光ビームをセル５、屈折
液３、純石英パイプ15、屈折液３、プリフォーム１、屈
折液３、純石英パイプ15、屈折液３、セル５を経由して
レンズ11により集光してディテクター13にて検出し、こ
れを公知の方法に従って演算処理することにより第２図
に示すごとき屈折率線図を得る。なお、同図において
ａ，ｂ，ｃ，ｄはそれぞれコアＡ、クラッＢ、屈折液
３、純石英パイプ15に対応する屈折率を示す。この場
合、最外輪に既知屈折率の純石英パイプ15が存在し、屈
折率線図上に現われるため、これを基準としてｎ＝1.45
8を引き得る。従って、コアとの屈折率差Δｎおよびコ
アとクラッドとの屈折率の比も屈折率線図より求めるこ
とができる。In this way, the light beam from the light source 9 passes through the cell 5, the refraction liquid 3, the pure quartz pipe 15, the refraction liquid 3, the preform 1, the refraction liquid 3, the pure quartz pipe 15, the refraction liquid 3, and the cell 5. The light is condensed by the lens 11, detected by the detector 13, and arithmetically processed according to a known method to obtain a refractive index diagram as shown in FIG. In the figure, a, b, c, and d respectively indicate the refractive index corresponding to the core A, the crack B, the refraction liquid 3, and the pure quartz pipe 15. In this case, a pure quartz pipe 15 having a known refractive index is present in the outermost ring and appears on the refractive index diagram, so that n = 1.45 is used as a reference.
You can subtract 8. Therefore, the refractive index difference Δn with the core and the refractive index ratio between the core and the clad can also be obtained from the refractive index diagram.
なお、上記の実施例では基準屈折率を与える部材として
とくに純石英パイプ15を用いているが、材質が純石英以
外でも物理的、化学的に安定した透明なパイプ状物体で
あれば（例えばＧ２Ｏ２等のドーパントの入った石英ガ
ラスパイプでもその屈折率が既知であれば）上記純石英
ガラスパイプ15の代りに使用することができる。In the above embodiment, the pure quartz pipe 15 is used as the member for giving the reference refractive index. However, if the material is not pure quartz and is a physically and chemically stable transparent pipe-shaped object (for example, G Even a quartz glass pipe containing a dopant such as 2 O 2 can be used instead of the above-mentioned pure quartz glass pipe 15 if its refractive index is known.
（発明の効果） 以上のように、本発明によればプリフォームアナライザ
ーを用いてプリフォームの屈折率を測定するに、プリフ
ォーム各部の屈折率の絶対値を精度よく測定できる方法
が提案される。(Effects of the Invention) As described above, according to the present invention, in measuring the refractive index of a preform using a preform analyzer, a method is proposed which can accurately measure the absolute value of the refractive index of each part of the preform. .
第１図は本発明方法を実施するための装置構成例を示す
断面図、第２図は本発明方法により得られるプリフォー
ムアナライザーの屈折率線図と装置部分との対応関係を
示す図、第３図は従来方法に使用される装置構成例の断
面図、第４図は同従来方法により得られるプリフォーム
アナライザーの屈折率線図とプリフォームとの対応関係
を示す図である。 １……プリフォーム、３……屈折液 ５……セル、９……光源 11……レンズ、13……ディテクタ 15……純石英パイプFIG. 1 is a cross-sectional view showing an example of the apparatus configuration for carrying out the method of the present invention, and FIG. 2 is a diagram showing the correspondence between the refractive index diagram of the preform analyzer obtained by the method of the present invention and the apparatus portion. FIG. 3 is a cross-sectional view of an apparatus configuration example used in a conventional method, and FIG. 4 is a diagram showing a correspondence relationship between a refractive index diagram of a preform analyzer obtained by the conventional method and preforms. 1 ... Preform, 3 ... Refraction liquid 5 ... Cell, 9 ... Light source 11 ... Lens, 13 ... Detector 15 ... Pure quartz pipe
Claims (4)
その長軸に対し直角方向に光ビームを当てて内部の屈折
率分布をプリフォームアナライザーにて測定するに、該
プリフォームのまわりに屈折液を介して既知屈折率の透
明のさや状物体を同心状にかぶせ、さらにその外側を屈
折液にて覆い、該プリフォームアナライザーの屈折率線
図上におけるさや状物体の屈折率レベルを基準としてプ
リフォームの屈折率を求める測定方法。1. A preform that does not contain a pure quartz layer inside is irradiated with a light beam in a direction perpendicular to its long axis to measure the internal refractive index distribution with a preform analyzer. A transparent sheath with a known refractive index is concentrically covered with a refractive liquid, and the outside is covered with a refractive liquid, and the refractive index level of the sheath is used as a reference on the refractive index diagram of the preform analyzer. As a method of measuring the refractive index of the preform.
を覆うパイプよりなる第１項の方法。2. The method of claim 1 wherein the sheath is a pipe that covers the entire perimeter of the preform.
２項の方法。3. The method according to claim 2, wherein the sheath is made of pure silica glass.
項の方法。4. A second body in which the sheath is made of quartz glass.
Method of terms.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10917485A JPH0617850B2 (en) | 1985-05-21 | 1985-05-21 | Method of measuring refractive index of preform |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP10917485A JPH0617850B2 (en) | 1985-05-21 | 1985-05-21 | Method of measuring refractive index of preform |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS61266932A JPS61266932A (en) | 1986-11-26 |
| JPH0617850B2 true JPH0617850B2 (en) | 1994-03-09 |
Family
ID=14503528
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP10917485A Expired - Fee Related JPH0617850B2 (en) | 1985-05-21 | 1985-05-21 | Method of measuring refractive index of preform |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0617850B2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB9010181D0 (en) * | 1990-05-04 | 1990-06-27 | York Technology Ltd | Apparatus for analysing optical properties of transparent objects |
| FR2700006B1 (en) * | 1992-12-24 | 1995-03-17 | France Telecom | Apparatus for measuring the index profile of an optical fiber preform comprising an external envelope and a core. |
-
1985
- 1985-05-21 JP JP10917485A patent/JPH0617850B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61266932A (en) | 1986-11-26 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| LAPS | Cancellation because of no payment of annual fees |