JP2661001B2 - Method and apparatus for measuring refractive index distribution - Google Patents
Method and apparatus for measuring refractive index distributionInfo
- Publication number
- JP2661001B2 JP2661001B2 JP1097055A JP9705589A JP2661001B2 JP 2661001 B2 JP2661001 B2 JP 2661001B2 JP 1097055 A JP1097055 A JP 1097055A JP 9705589 A JP9705589 A JP 9705589A JP 2661001 B2 JP2661001 B2 JP 2661001B2
- Authority
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- Japan
- Prior art keywords
- refractive index
- index distribution
- light
- cylindrical glass
- incident
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- 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
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- 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
本発明は、例えば光ファイバ用プリフォームやロッド
レンズに使用される円柱ガラスの屈折率分布の測定方法
及び装置に関するものである。The present invention relates to a method and an apparatus for measuring a refractive index distribution of a cylindrical glass used for a preform or a rod lens for an optical fiber, for example.
光ファイバ用プリフォーム（母材）やロッドレンズに
使用される円柱ガラスは、半径方向の屈折率がほぼ２乗
分布、軸方向の屈折率は均一になっている。これを線引
きして光ファイバが形成される。線引き前のプリフォー
ムの屈折率分布を正確に測定することが良好な製品を得
るために必要である。 この屈折率分布の測定法には従来からの種々の方法が
ある。例えば特開昭63−95336号公報あるいは特開昭63
−95337号公報には光ファイバ用のプリフォームの中心
軸と垂直方向から光線を入射し、その出射光の出射角を
求めてプリフォームの屈折率分布を測定する方法が開示
されている。特開昭63−95336号公報に開示された屈折
率分布の測定法は、第８図に示すようにプリフォームか
ら出射されTVカメラの観察面43に投影された出射光の０
次の回折光スポット30、１次の回折光スポット31、２次
の回折光スポット32・・・の中から０次の回折光スポッ
ト30を２次元的に解析して取り出し、この０次の回折光
スポット30のｘ座標xfと出射光学系の焦点距離ｆとから
出射角φを φ＝tan-1（xf/f） で求めている。そしてこの出射角φからプリフォーム１
の屈折率分布ｎ（ｒ）を次式 で算出している。 特開昭63−95337号公報に開示された屈折率分布の測
定方法は、出射光学系にスリットを設けて出射光の０次
の回折光スポット30だけを取り出すことにより、高次の
回折光スポットの影響を受けずに屈折率分布を測定して
いる。In a cylindrical glass used for a preform (base material) for optical fibers or a rod lens, the refractive index in the radial direction is substantially squared distribution, and the refractive index in the axial direction is uniform. This is drawn to form an optical fiber. It is necessary to accurately measure the refractive index distribution of the preform before drawing in order to obtain a good product. There are various conventional methods for measuring the refractive index distribution. For example, JP-A-63-95336 or JP-A-63-95336
Japanese Patent Application Laid-Open No. 95337/1995 discloses a method in which a light beam is incident from a direction perpendicular to the central axis of an optical fiber preform, and the exit angle of the emitted light is determined to measure the refractive index distribution of the preform. The method of measuring the refractive index distribution disclosed in Japanese Patent Application Laid-Open No. 63-95336 discloses a method of measuring the refractive index distribution of light emitted from a preform and projected onto an observation surface 43 of a TV camera as shown in FIG.
The 0th-order diffracted light spot 30 is two-dimensionally analyzed and extracted from the next-order diffracted light spot 30, the first-order diffracted light spot 31, the second-order diffracted light spot 32,. the output angle phi from the light spot 30 x coordinate x f and the focal length f of the emitting optical system are calculated by φ = tan -1 (x f / f). And from this emission angle φ, the preform 1
The refractive index distribution n (r) of It is calculated by The method of measuring the refractive index distribution disclosed in Japanese Patent Application Laid-Open No. 63-95337 discloses a method of providing a slit in an output optical system and extracting only a zero-order diffracted light spot 30 of the output light, thereby obtaining a higher-order diffracted light spot. The refractive index distribution is measured without being affected by.
第９図に示すように、光ファイバ用のプリフォーム１
の中心軸２に垂直な平面Ｐを通り、中心軸２の垂直方向
から入射した入射光線41はプリフォーム１で屈折し、プ
リフォーム１からの出射光線42は平面Ｐと垂直な投影面
Ｑに至る。この入射光線41と出射光線42の点ａ、ｂ、ｃ
はプリフォーム１の軸方向の屈折率に変化がない場合は
平面Ｐ上に存在する。なお、ｄは入射光線41の延長線と
投影面Ｑの交点を示す。 プリフォーム１を例えばVAD法で軸方向にガラスを成
長させていくときに、そのガラス内に脈理が生じ、軸方
向の屈折率分布に変動を生じることがある。脈理がある
プリフォームに入射光線41を入射させると、出射光線42
は散乱し、第８図に示すように投影面Ｑ上の点Ｃを通る
傾きのある直線43上に分散する。そして場合によっては
最大強度となる０次の回析光スポットの位置が第８図の
点ｅで示す位置へ移動し、点Ｃにおける光の強度がほと
んどなくなることもある。 このため、従来例のように０次の回析光スポットの位
置を測定して出射角φを求める方法であると、第10図に
示すようにプリフォーム１の脈理が強い領域51、52で出
射角φが正確に測定されず誤差が生じてしまう。この誤
差がある出射角φにより屈折率分布を求めると、求めた
屈折率分布は第11図に示すように脈理の大きい部分で大
きく変動し、正確な屈折率分布を得ることが困難である
という問題があった。 本発明はかかる問題を解決するためになされたもので
あり、脈理があるプリフォームであっても正確に屈折率
分布を得ることができる測定方法と測定装置を得ること
を目的とするものである。As shown in FIG. 9, a preform 1 for an optical fiber
The incident light beam 41 that has passed through a plane P perpendicular to the central axis 2 of the optical axis and is incident from the direction perpendicular to the central axis 2 is refracted by the preform 1, and the outgoing light ray 42 from the preform 1 Reach. The points a, b, and c of the incident light beam 41 and the outgoing light beam 42
Exists on the plane P when there is no change in the refractive index in the axial direction of the preform 1. Note that d indicates the intersection of the extension of the incident light beam 41 and the projection plane Q. When growing glass in the axial direction of the preform 1 by, for example, the VAD method, striae may occur in the glass, and the refractive index distribution in the axial direction may fluctuate. When the incident light beam 41 is incident on the preform having striae, the outgoing light beam 42
Are scattered and dispersed on an inclined straight line 43 passing through a point C on the projection plane Q as shown in FIG. In some cases, the position of the zero-order diffraction light spot having the maximum intensity moves to the position indicated by the point e in FIG. 8, and the light intensity at the point C may be almost zero. For this reason, according to the method of measuring the position of the zero-order diffraction light spot as in the conventional example and obtaining the emission angle φ, as shown in FIG. In this case, the emission angle φ is not accurately measured, causing an error. When the refractive index distribution is obtained from the exit angle φ having this error, the obtained refractive index distribution greatly fluctuates in a portion having a large stria as shown in FIG. 11, and it is difficult to obtain an accurate refractive index distribution. There was a problem. The present invention has been made in order to solve such a problem, and an object of the present invention is to provide a measuring method and a measuring apparatus capable of accurately obtaining a refractive index distribution even in a preform having striae. is there.
上記課題を解決するための本発明を適用する屈折率分
布の測定方法は、軸方向には均一な屈折率、径方向には
屈折率分布が変化する円柱ガラスの中心軸と垂直方向か
ら光線を入射し、その出射光の出射角を測定して屈折率
分布を算出する屈折率分布の測定方法において、該円柱
ガラスの脈理部からの出射光より投影される０次からｎ
次の回折光スポット群のつながりを直線近似し、この直
線と、円柱ガラスの中心軸に垂直で入射光が通る平面と
の交点の位置から出射角を測定することを特徴としてい
る。 同じく本発明を適用する屈折率分布の測定装置は、第
１図、第２図、第３図に示すように、円柱ガラス１に、
その中心軸２と垂直な方向から光線を入射する入射光学
系６・７、入射光学系６・７から入射して円柱ガラス１
の脈理部を通った出射光の０次からｎ次の回折スポット
群を検出する撮像手段10、撮像手段10で検出された回折
光スポット群のつながりを直線近似する演算手段13、演
算手段13により得られた直線と、円柱ガラスの中心軸に
垂直で入射光が通る平面との交点の位置を求める位置算
出手段14、および位置算出手段14で算出した交点の位置
から出射角を演算する出射角演算手段15を有している。The method of measuring the refractive index distribution to which the present invention is applied to solve the above-mentioned problem is as follows: a uniform refractive index in the axial direction, a light beam from a direction perpendicular to the central axis of the cylindrical glass in which the refractive index distribution changes in the radial direction. In the refractive index distribution measuring method of calculating the refractive index distribution by measuring the exit angle of the incident light, the 0th to nth order projected from the light emitted from the striae of the cylindrical glass.
It is characterized in that a straight line approximation is made to the connection of the next group of diffracted light spots, and the exit angle is measured from the position of the intersection of this straight line and a plane perpendicular to the central axis of the cylindrical glass and through which incident light passes. A measuring apparatus for a refractive index distribution to which the present invention is applied is also provided on a cylindrical glass 1 as shown in FIGS. 1, 2, and 3.
The incident optical systems 6.7 and 7 which receive light rays from the direction perpendicular to the central axis 2, and the cylindrical glass 1 which is incident from the incident optical systems 6.7 and
Imaging means 10 for detecting a 0th-order to nth-order diffraction spot group of the outgoing light passing through the striae of the above, computing means 13 for linearly approximating the connection of the diffracted light spot groups detected by the imaging means 10, and computing means 13 Calculating the position of the intersection of the straight line obtained by the above and the plane perpendicular to the center axis of the cylindrical glass and through which the incident light passes, and the emission calculating the emission angle from the position of the intersection calculated by the position calculation means 14. It has angle calculation means 15.
上記本発明の装置を用いた本発明の測定方法では、円
柱ガラスの中心軸と垂直方向から入射した光の出射光の
回折光スポットのすべての位置データを演算手段で２値
化して直線近似し、この近似直線と入射光が通る平面と
の交点の位置により出射角を求めるから、出射角を求め
るためのデータが多くなり出射角の測定精度を向上する
と共に出射光の像が入射光が通る平面上にはなくても出
射角を求めることができる。In the measuring method of the present invention using the above-described apparatus of the present invention, all the position data of the diffracted light spot of the outgoing light of the light incident from the direction perpendicular to the central axis of the cylindrical glass are binarized by the arithmetic means and linearly approximated. Since the emission angle is determined by the position of the intersection of the approximate straight line and the plane through which the incident light passes, the data for determining the emission angle increases, the measurement accuracy of the emission angle improves, and the image of the emission light passes through the incident light. The outgoing angle can be obtained even if the light is not on a plane.
以下、本発明の実施例を詳細に説明する。 第１図、第２図は本発明の一実施例の概略構成を示
し、第１図は光ファイバ用のプリフォーム１の中心軸２
と同方向であるｙ軸方向から視た平面図、第２図は中心
軸２と垂直なｘ軸方向から視た側面図である。図におい
て、３はプリフォーム１を装着したセルであり、セル３
内にはプリフォーム１の表面における急激な屈折率変化
を除くためにマッチングオイル４が満たされている。５
はセル３が設置された移動テーブルであり、移動テーブ
ル５によりプリフォーム１がｘ軸とｙ軸方向に移動され
る。 ６は例えばHe−Neレーザ発振器からなる光源、７は入
射光学系を構成するレンズであり、レンズ７は光源６か
らの入射光をプリフォーム１の中心で最小になるように
収斂している。８はプリフォーム１から出射した出射光
９の投影像を形成するスクリーン、10はスクリーン８に
投影された投影像を観察するTVカメラ、11はTVカメラ10
で得た投影像の位置から出射角をもとめて屈折率分布を
演算する制御部である。 第３図は制御部11の構成を示すブロック図である。図
において、12はTVカメラ10で観察したスクリーン８上の
投影像のデータを蓄えるフレームメモリ、13はフレーム
メモリ12に蓄えられたデータを２値化し直線近似を行な
う演算手段、14は演算手段13で得た直線とプリフォーム
１の中心軸２に垂直で入射光が通る平面すなわち第９図
における平面Ｐとの交点ｃを求める位置算出手段、15は
位置算出手段14で求めた交点の座標から出射角φを演算
する出射角演算手段である。16は出射角演算手段で演算
した出射角φによりプリフォーム１の屈折率分布を演算
する屈折率分布演算手段、17は表示部および記録部から
なる出力手段である。 プリフォーム１の屈折率分布を測定するときは、まず
光源６から送られプリフォーム１を通って投影された出
射光９のスクリーン８上における０次からｎ次の回折光
スポット群の各投影像30〜32（第４図参照）をTVカメラ
10で観察し、その出力信号をフレームメモリ12に取り込
む。次に、フレームメモリ12に蓄えられた各投影像のデ
ータを演算手段13で２値化して最小２乗法により直線近
似を行ない、第４図に示す近似直線20を求める。その
後、位置算出手段14で近似直線20とプリフォーム１の中
心軸２と垂直で入射光が通る平面、すなわち第４図に示
すｘ軸との交点xcを求め、プリフォーム１の中心を通る
出射光の投影像を基準点Ｏとした交点xcの座標値から出
射角演算手段15で出射角φを演算し、演算した出射角φ
をメモリ18で蓄える。 この動作を移動テーブル５を移動させながらプリフォ
ーム１の半径方向の各位置で行ない、各位置における出
射角φを求めてメモリ18に記憶させる。このメモリ18に
記憶させた各出射角φを屈折率分布演算手段16に送って
屈折率分布ｎ（ｒ）を演算して出力手段17に送る。 上記のようにして、例えば第５図に示すようなコアの
最大屈折率n1でクラッドの屈折率n2のプリフォーム１
の、入射位置ｒと出射角φの関係を測定した結果を第６
図に示す。同図に示すようにプリフォーム１内に脈理が
強い領域51、52があっても出射角φの変化に大きな変動
は見られなかった。出射角φにより屈折率分布ｎ（ｒ）
を求めると第７図に示す特性を得ることができた。この
測定を30回繰り返して次式で示す比屈折率差Δ Δ＝（n1−n2）x100/n1 を求め、この比屈折率差Δの標準偏差σを算出して比屈
折率差Δで正規化した結果、 （σ／Δ）＝0.001 を得ることができた。また脈理により出射光９の投影像
が平面Ｐ上に形成されない場合であっても上記精度と同
程度の測定精度で屈折率分布を測定することができた。 なお上記実施例においてはスクリーン８とTVカメラ10
で出射光の投影像を観察する場合について説明したが、
撮像素子により投影像を観察しても上記実施例と同様な
作用を奏することができる。Hereinafter, embodiments of the present invention will be described in detail. 1 and 2 show a schematic configuration of an embodiment of the present invention. FIG. 1 shows a central axis 2 of a preform 1 for an optical fiber.
FIG. 2 is a side view as seen from the y-axis direction which is the same direction as FIG. In the figure, reference numeral 3 denotes a cell on which the preform 1 is mounted, and cell 3
The inside is filled with a matching oil 4 in order to remove a sudden change in the refractive index on the surface of the preform 1. 5
Is a moving table on which the cells 3 are installed, and the preform 1 is moved by the moving table 5 in the x-axis and y-axis directions. Reference numeral 6 denotes a light source composed of, for example, a He-Ne laser oscillator, and reference numeral 7 denotes a lens constituting an incident optical system. The lens 7 converges incident light from the light source 6 so as to be minimum at the center of the preform 1. Reference numeral 8 denotes a screen for forming a projection image of the light 9 emitted from the preform 1, reference numeral 10 denotes a TV camera for observing the projection image projected on the screen 8, and reference numeral 11 denotes a TV camera 10.
Is a control unit that calculates the refractive index distribution by obtaining the emission angle from the position of the projection image obtained in step (1). FIG. 3 is a block diagram showing the configuration of the control unit 11. In the figure, reference numeral 12 denotes a frame memory for storing data of a projected image on the screen 8 observed by the TV camera 10, 13 denotes a calculating means for binarizing the data stored in the frame memory 12 and performs linear approximation, and 14 denotes a calculating means 13 And a plane perpendicular to the central axis 2 of the preform 1 and through which the incident light passes, ie, a plane P in FIG. This is an emission angle calculation means for calculating the emission angle φ. Reference numeral 16 denotes a refractive index distribution calculating means for calculating the refractive index distribution of the preform 1 based on the output angle φ calculated by the output angle calculating means, and 17 denotes an output means comprising a display unit and a recording unit. When measuring the refractive index distribution of the preform 1, first, each projected image of the 0th to nth order diffracted light spot group on the screen 8 of the outgoing light 9 sent from the light source 6 and projected through the preform 1 30-32 (see Fig. 4) TV camera
Observation is made at 10, and the output signal is taken into the frame memory 12. Next, the data of each projection image stored in the frame memory 12 is binarized by the arithmetic means 13 and a straight line approximation is performed by the least squares method to obtain an approximate straight line 20 shown in FIG. Then, the position calculating unit 14 at the approximate straight line 20 and the preform 1 of the central axis 2 and the plane in which incident light passes in the vertical, i.e. obtain the intersection x c and x-axis shown in FIG. 4, through the center of the preform 1 calculates the output angle φ by emission angle calculating means 15 a projection image of the emitted light from the coordinate values of the intersection point x c where a reference point O, the outgoing angle φ computed
Is stored in the memory 18. This operation is performed at each position in the radial direction of the preform 1 while moving the moving table 5, and the emission angle φ at each position is obtained and stored in the memory 18. Each output angle φ stored in the memory 18 is sent to the refractive index distribution calculating means 16 to calculate the refractive index distribution n (r) and sent to the output means 17. As described above, for example, the fifth preform 1 of refractive index n 2 of the cladding in the maximum refractive index n 1 of the core as shown in FIG.
Of the relationship between the incident position r and the exit angle φ
Shown in the figure. As shown in the figure, even when there were strong striae regions 51 and 52 in the preform 1, no significant change was observed in the change of the emission angle φ. Refractive index distribution n (r) depending on emission angle φ
Was obtained, the characteristics shown in FIG. 7 could be obtained. This measurement is repeated 30 times to obtain a relative refractive index difference ΔΔ = (n 1 −n 2 ) × 100 / n 1 represented by the following equation, and a standard deviation σ of the relative refractive index difference Δ is calculated to obtain a relative refractive index difference. As a result of normalization by Δ, (σ / Δ) = 0.001 was obtained. Further, even when the projected image of the outgoing light 9 was not formed on the plane P due to striae, the refractive index distribution could be measured with the same measurement accuracy as the above accuracy. In the above embodiment, the screen 8 and the TV camera 10 are used.
In the above, the case where the projected image of the emitted light is observed has been described,
Even when the projected image is observed by the image sensor, the same operation as in the above embodiment can be achieved.
以上説明したように本発明によれば、円柱ガラスの中
心軸と垂直方向に入射した光の出射光の散乱された投影
像のすべての位置データを直線近似し、この近似直線と
同軸円柱ガラスの中心軸と垂直で入射光が通る平面との
交点の位置により出射角を求めるから、出射角を求める
ためのデータ数が多くなり出射角の検出精度を高めるこ
とができ、屈折率分布の測定精度を向上させることがで
きる。 また投影を直線近似して得た近似直線を用い出射角を
求めるから、出射光が散乱され、その像が入射光が通る
平面上にない場合であっても精度良く出射角を求めるこ
とができる。As described above, according to the present invention, all the position data of the scattered projected image of the emitted light of the light incident in the direction perpendicular to the central axis of the cylindrical glass are linearly approximated, and this approximate straight line and the coaxial cylindrical glass Since the exit angle is determined by the position of the intersection of the plane perpendicular to the central axis and the plane through which the incident light passes, the number of data for determining the exit angle increases, the detection accuracy of the exit angle can be increased, and the measurement accuracy of the refractive index distribution can be improved. Can be improved. Further, since the emission angle is obtained by using an approximate straight line obtained by linearly approximating the projection, the emission light is scattered and the emission angle can be accurately obtained even when the image is not on a plane through which the incident light passes. .
第１図は本発明を適用する装置の実施例の概略平面図、
第２図はその側面図、第３図は上記実施例の制御部を示
すブロック図、第４図は上記実施例の動作を示す説明
図、第５図はプリフォームの屈折率分布を示す特性図、
第６図は上記実施例により測定した出射角特性図、第７
図はその出射角特性から得た屈折率分布特性図、第８図
は従来例の動作を示す説明図、第９図は屈折率分布測定
の原理を示す説明図、第10図は従来例による出射角特性
図、第11図は従来例により得た屈折率分布特性図であ
る。 １……プリフォーム、３……セル、６……光源、７……
レンズ ８……スクリーン、９……出射光、10……TVカメラ 12……フレームメモリ、13……演算手段、14……位置算
出手段 15……出射角演算手段FIG. 1 is a schematic plan view of an embodiment of an apparatus to which the present invention is applied,
FIG. 2 is a side view thereof, FIG. 3 is a block diagram showing a control unit of the above embodiment, FIG. 4 is an explanatory diagram showing the operation of the above embodiment, and FIG. 5 is a characteristic showing a refractive index distribution of the preform. Figure,
FIG. 6 is an emission angle characteristic diagram measured by the above embodiment, and FIG.
FIG. 8 is a graph showing a refractive index distribution characteristic obtained from the emission angle characteristic, FIG. 8 is an explanatory diagram showing the operation of the conventional example, FIG. 9 is an explanatory diagram showing the principle of the refractive index distribution measurement, and FIG. FIG. 11 is an emission angle characteristic diagram, and FIG. 11 is a refractive index distribution characteristic diagram obtained by a conventional example. 1 ... preform, 3 ... cell, 6 ... light source, 7 ...
Lens 8 ... Screen, 9 ... Outgoing light, 10 ... TV camera 12 ... Frame memory, 13 ... Calculating means, 14 ... Position calculating means 15 ... Outgoing angle calculating means
───────────────────────────────────────────────────── フロントページの続き (72)発明者 山口 一郎 埼玉県和光市広沢２番１号 理化学研究 所内 (72)発明者 島田 忠克 群馬県安中市磯部２丁目13番１号 信越 化学工業株式会社精密機能材料研究所内 (72)発明者 神屋 和雄 群馬県安中市磯部２丁目13番１号 信越 化学工業株式会社精密機能材料研究所内 (72)発明者 鈴木 敏之 東京都千代田区丸の内１丁目４番２号 信越エンジニアリング株式会社内 (56)参考文献 特開 昭63−95336（ＪＰ，Ａ) ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Ichiro Yamaguchi 2-1 Hirosawa, Wako-shi, Saitama Pref. Inside the Precision Functional Materials Laboratory (72) Kazuo Kamiya 2-13-1, Isobe, Annaka-shi, Gunma Shin-Etsu Chemical Co., Ltd.Precision Functional Materials Laboratory (72) Inventor Toshiyuki Suzuki 1-4-4 Marunouchi, Chiyoda-ku, Tokyo No. 2 Shin-Etsu Engineering Co., Ltd. (56) References JP-A-63-95336 (JP, A)
Claims (2)
率分布が変化する円柱ガラスの中心軸と垂直方向から光
線を入射し、その出射光の出射角を測定して屈折率分布
を算出する屈折率分布の測定方法において、該円柱ガラ
スの脈理部からの出射光より投影される０次からｎ次の
回折光スポット群のつながりを直線近似し、この直線
と、円柱ガラスの中心軸に垂直で入射光が通る平面との
交点の位置から出射角を測定することを特徴とする屈折
率分布の測定方法。1. A light beam is incident from a direction perpendicular to the central axis of a cylindrical glass whose refractive index distribution changes in the axial direction and the refractive index distribution changes in the radial direction, and the exit angle of the exit light is measured to determine the refractive index. In the method of measuring the refractive index distribution for calculating the distribution, the connection of the 0th-order to nth-order diffracted light spot groups projected from the light emitted from the striae of the cylindrical glass is linearly approximated, and this straight line and the cylindrical glass A method of measuring a refractive index distribution, wherein an exit angle is measured from a position of an intersection with a plane perpendicular to a central axis of the above and through which incident light passes.
光線を入射する入射光学系、 該入射光学系から入射して円柱ガラスの脈理部を通った
出射光の０次からｎ次の回折スポット群を検出する撮像
手段、 該撮像手段で検出された回折光スポット群のつながりを
直線近似する演算手段、 該演算手段により得られた直線と、円柱ガラスの中心軸
に垂直で入射光が通る平面との交点の位置を求める位置
算出手段、および 該位置算出手段で算出した交点の位置から出射角を演算
する出射角演算手段を有することを特徴とする屈折率分
布の測定装置。2. An incident optical system for injecting a light beam into a cylindrical glass in a direction perpendicular to the central axis of the cylindrical glass, and a 0th to nth order light emitted from the incident optical system and passed through a stria of the cylindrical glass. Imaging means for detecting a group of diffraction spots; calculating means for linearly approximating the connection of the groups of diffracted light spots detected by the imaging means; and a straight line obtained by the calculating means and incident light perpendicular to the central axis of the cylindrical glass. An apparatus for measuring a refractive index distribution, comprising: position calculating means for calculating the position of an intersection with a passing plane; and emission angle calculating means for calculating an emission angle from the position of the intersection calculated by the position calculating means.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1097055A JP2661001B2 (en) | 1989-04-17 | 1989-04-17 | Method and apparatus for measuring refractive index distribution |
| US07/509,909 US5078488A (en) | 1989-04-17 | 1990-04-16 | Method and apparatus for determining refractive index distribution |
| DE69013963T DE69013963T2 (en) | 1989-04-17 | 1990-04-17 | Method and device for determining the refractive index profile. |
| EP90107269A EP0393591B1 (en) | 1989-04-17 | 1990-04-17 | Method and apparatus for determining refractive index distribution |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1097055A JP2661001B2 (en) | 1989-04-17 | 1989-04-17 | Method and apparatus for measuring refractive index distribution |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02275334A JPH02275334A (en) | 1990-11-09 |
| JP2661001B2 true JP2661001B2 (en) | 1997-10-08 |
Family
ID=14181972
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1097055A Expired - Lifetime JP2661001B2 (en) | 1989-04-17 | 1989-04-17 | Method and apparatus for measuring refractive index distribution |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2661001B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110068278A (en) * | 2019-04-22 | 2019-07-30 | 南京理工大学 | Non-contact optical fiber preform size real-time measurement system and method based on FPGA |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6395336A (en) * | 1986-10-10 | 1988-04-26 | Fujikura Ltd | Measurement of refractive index distribution |
-
1989
- 1989-04-17 JP JP1097055A patent/JP2661001B2/en not_active Expired - Lifetime
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN110068278A (en) * | 2019-04-22 | 2019-07-30 | 南京理工大学 | Non-contact optical fiber preform size real-time measurement system and method based on FPGA |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH02275334A (en) | 1990-11-09 |
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