JP4885471B2 - Method for measuring refractive index distribution of preform rod - Google Patents
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Description
本発明は、プリフォームロッドの屈折率分布測定方法に係り、特に、内部に屈折率分布を有するプリフォームロッドの屈折率分布測定方法に関する。 The present invention relates to a preform rod refractive index distribution measuring method , and more particularly to a preform rod refractive index distribution measuring method having a refractive index distribution therein.
最近の通信ネットワークの進展に伴い、光ファイバケーブルの需要はますます増加する傾向にある。光ファイバケーブルを構成している一要素である光ファイバはまずＶＡＤ法あるいはＭＣＶＤ法等によりプリフォームロッド（光ファイバ母材）と呼ばれる透明体を作成し、それを所定の径まで線引きして製造している。プリフォームロッドは屈折率の高いコア部とその周囲の屈折率がコア部より低いクラッドとからなっている。 With the recent development of communication networks, the demand for optical fiber cables tends to increase. An optical fiber, which is an element constituting an optical fiber cable, is manufactured by first creating a transparent body called a preform rod (optical fiber preform) by the VAD method or MCVD method and drawing it to a predetermined diameter. is doing. The preform rod includes a core portion having a high refractive index and a clad having a lower refractive index around the core portion.
ところで、光ファイバに必要とされる特性が設計通りになっているかを判定する指標の一つに屈折率分布を測定する方法がある。光ファイバの屈折率分布を測定する場合は通常プリフォームロッドの状態で測定するが、プリフォームロッドを屈折率が既知である屈折率整合液（マッチングオイル）中に浸漬して、プリフォームロッドの軸方向に対して垂直な角度で光源からレーザ光等を入射して、透過してきた光の角度や位置から屈折率分布を測定する方法がよく行われている。 By the way, there is a method of measuring the refractive index distribution as one of indicators for determining whether the characteristics required for the optical fiber are as designed. When measuring the refractive index distribution of an optical fiber, it is usually measured in the state of a preform rod, but the preform rod is immersed in a refractive index matching liquid (matching oil) whose refractive index is known, and the preform rod is A common method is to measure the refractive index distribution from the angle or position of light that has passed through a laser beam or the like incident from a light source at an angle perpendicular to the axial direction.
このようなプリフォームロッドの屈折率分布を測定する方法として、強度分布を修正した光をプリフォームロッドに照射し、その透過した光の像をスクリーンに投影し、投影された光の像からラインセンサカメラを用いて得た光の強度分布データを処理して、プリフォームロッドを透過して屈折した光のスクリーン上の位置を決定し、その光の位置の変化から求めた屈折角からプリフォームロッド内部の屈折率分布を測定する屈折率分布測定装置および測定方法が提案されている（例えば、特許文献１参照）。 As a method for measuring the refractive index distribution of such a preform rod, the preform rod is irradiated with light whose intensity distribution has been corrected, an image of the transmitted light is projected onto a screen, and a line is formed from the projected light image. The light intensity distribution data obtained using the sensor camera is processed to determine the position on the screen of the light refracted through the preform rod, and the preform is determined from the refraction angle determined from the change in the light position. A refractive index distribution measuring device and a measuring method for measuring a refractive index distribution inside a rod have been proposed (see, for example, Patent Document 1).
この屈折率分布測定装置および測定方法によれば、光がプリフォームロッドに入射する前と、透過した後の両方で光の強度分布を整えることができ、また、ラインセンサカメラで取り込まれた光の強度分布のデータから、数値演算によって光の位置を求めることによって、プリフォームロッドを透過した屈折後の光の位置を正確に決定することができる。
なお、このような光の強度分布のパターンには、多くの雑音（ノイズ）が残されているので、この雑音成分を低減するために画像処理が施される。
According to this refractive index distribution measuring apparatus and measuring method, the light intensity distribution can be adjusted both before and after the light enters the preform rod, and the light captured by the line sensor camera can be adjusted. By calculating the position of light from the intensity distribution data by numerical calculation, it is possible to accurately determine the position of the light after refraction transmitted through the preform rod.
Since a lot of noise (noise) remains in such a light intensity distribution pattern, image processing is performed to reduce this noise component.
しかしながら、背景技術において示した屈折率分布測定装置および測定方法では、プリフォームロッド内部の屈折率分布を計算する際、ラインセンサカメラによる走査で演算部に取り込まれる受光データをそのまま利用して、雑音除去を施して光の位置を決定してから屈折角および屈折率のデータを求めるように演算処理するが、ラインセンサカメラから演算部に取り込まれる受光データは１回の走査によるものなので、測定誤差が大きくなる虞があった。 However, in the refractive index distribution measuring apparatus and measuring method shown in the background art, when calculating the refractive index distribution inside the preform rod, the received light data taken into the calculation unit by scanning with the line sensor camera is used as it is, and noise is calculated. After calculating the position of the light after removal, the calculation processing is performed to obtain the data of the refraction angle and the refractive index. However, since the received light data taken from the line sensor camera to the calculation unit is obtained by one scan, the measurement error There was a risk of increasing.
本願発明者は、ラインセンサカメラなどの画像撮影装置による１回の走査では測定誤差が大きくなることについて、以下のように検証を行なっている。 The inventor of the present application verifies that the measurement error increases by one scanning by an image photographing apparatus such as a line sensor camera as follows.
検証方法に用いたプリフォームロッドの屈折率分布の測定は、まず、屈折率整合液が収容された屈折率整合液槽に、内部に屈折率分布を有するプリフォームロッドを浸漬した状態で、屈折率整合液槽の外部に配置された画像投影装置により屈折率整合液中に浸漬されたプリフォームロッドに対して画像を投影し、そのプリフォームロッドを通過してきた投光画像を、画像投影装置と反対側に配置された画像撮影装置で撮像して受光データを得た。この受光データから歪み量を解析することで偏向関数を求め、その偏向関数に基づきプリフォームロッドの屈折率分布を求めた。この際、歪み量、偏向関数および屈折率分布の各演算処理の過程で雑音処理を行なった。 The refractive index distribution of the preform rod used in the verification method is measured by first refracting the preform rod having a refractive index distribution inside the refractive index matching liquid tank containing the refractive index matching liquid. An image projection device that projects an image onto a preform rod immersed in the refractive index matching solution by an image projection device disposed outside the index matching solution tank, and displays the projected image that has passed through the preform rod. The received light data was obtained by taking an image with an image photographing device arranged on the opposite side of the surface. A deflection function was obtained by analyzing the amount of distortion from the received light data, and the refractive index distribution of the preform rod was obtained based on the deflection function. At this time, noise processing was performed in the course of each calculation processing of the distortion amount, the deflection function, and the refractive index distribution.
なお、画像撮影装置は一次元配列の半導体素子から成るラインセンサカメラではなく二次元配列の半導体素子から成るカメラを使用した。 Note that the image capturing apparatus used a camera made of a two-dimensional array of semiconductor elements instead of a line sensor camera made of a one-dimensional array of semiconductor elements.
このようなプリフォームロッドの屈折率分布の測定を同じ位置で複数回行なったところ、複数回測定した受光データの値の統計上の平均値は何度測定してもほぼ同じ値を示すが、測定値のばらつきが大きいことがわかった。したがって、画像撮影装置による１回の走査による測定結果では測定誤差が大きくなることがわかった。 When the measurement of the refractive index distribution of such a preform rod was performed several times at the same position, the statistical average value of the received light data measured multiple times shows almost the same value no matter how many times it is measured, It was found that the measured values varied greatly. Therefore, it has been found that the measurement error is large in the measurement result of one scan by the image photographing apparatus.
なお、この測定値のばらつきは受光データに発生する雑音が主な原因であるが、この雑音は画像投影装置の光源の明るさの揺らぎや、ＣＣＤ（charge copuled device）カメラやＣＣＤラインセンサカメラ等の半導体素子で受光した際の電気的なノイズ等によるものである。このことを実証するために、測定系や測定環境を固定して、測定誤差が出にくくした状態で繰り返し測定したところ、受光データの値がランダムな雑音の影響を受け、受光データの値は測定するたびに変化していた。ここで、半導体素子で受光した受光データとは、光の強さを表す数値データであり、これを輝度として目に見える形に演算処理すると、１次元の配列となる直線上の投光画像データ、又は２次元の配列になっている投光画像データとなる。したがって、受光データを２次元の平面画像に直してみると、雑音の状態が目で見ると非常に明らかで、受光量（輝度）がランダムに揺らぐ雑音となって現れている。即ち、投光画像の歪み具合から屈折率を測定するこの方法では、これらの雑音の影響を強く受け、測定精度、特に、繰り返し再現性を見るとばらつきとなって現れ、測定誤差の大きな要因となる。 This variation in measured values is mainly caused by noise generated in the received light data. This noise is caused by fluctuations in the brightness of the light source of the image projection device, CCD (charge copuled device) camera, CCD line sensor camera, etc. This is due to electrical noise or the like when light is received by the semiconductor element. In order to verify this, when the measurement system and measurement environment were fixed and measurement was repeated with less measurement error, the received data value was affected by random noise, and the received data value was measured. Every time I changed it. Here, the light reception data received by the semiconductor element is numerical data representing the intensity of light, and when this is arithmetically processed as a luminance, the projected image data on a straight line that becomes a one-dimensional array Or, the projection image data is a two-dimensional array. Therefore, when the received light data is converted into a two-dimensional planar image, the state of noise is very obvious when visually observed, and the received light amount (luminance) appears as noise that fluctuates randomly. In other words, this method of measuring the refractive index based on the degree of distortion of the projected image is strongly influenced by these noises, and it appears as variations when looking at measurement accuracy, especially repeatability, which is a major factor of measurement error. Become.
本発明は、このような従来の難点を解決するためになされたもので、内部に屈折率分布を有するプリフォームロッドの屈折率分布を測定する際、画像撮影装置から出力される受光データに雑音が発生しても高精度に測定できるプリフォームロッドの屈折率分布測定方法を提供することを目的とする。 The present invention has been made to solve such a conventional problem, and when measuring the refractive index distribution of a preform rod having a refractive index distribution therein, noise is included in the received light data output from the image capturing apparatus. It is an object of the present invention to provide a method for measuring the refractive index distribution of a preform rod that can be measured with high accuracy even if the occurrence of the above occurs.
本発明の第１の態様は、屈折率整合液が収容された屈折率整合液槽と、屈折率整合液中に浸漬され内部に屈折率分布を有するプリフォームロッドと、屈折率整合液槽の外部に配置され画像を投影する画像投影装置と、屈折率整合液中に浸漬されたプリフォームロッド及び画像投影装置と同一光軸上で且つ当該プリフォームロッドを間にして画像投影装置と反対側に配置され、２次元配列の受光データにするカメラとからなる光学系により、屈折率整合液中に浸漬されたプリフォームロッドを通過してきた投光画像をカメラにより撮像し、この撮像により得られた２次元配列の受光データを解析してプリフォームロッドの屈折率分布を測定する方法において、屈折率整合液中に浸漬されたプリフォームロッドを通過してきた投光画像をカメラで複数回撮像してそれぞれの２次元配列の受光データを出力し、各受光データの値のばらつきを小さくするために、当該各受光データの２次元配列を、白黒間を多段階に区分した複数のブロックから成るデータにしてそれぞれのブロック位置で重ね合わせ処理し、この重ね合わせ処理されたデータをそれぞれのブロック位置で平均化処理及びメジアン値抽出処理のうち少なくとも１つで処理することにより、当該各受光データを、２次元配列から当該受光データに生じた雑音を示す色の濃淡の異なるブロックの数を減少させた１つの投光画像データにして、当該１つの投光画像データからプリフォームロッドの歪み量を解析することでプリフォームロッドの屈折率分布を測定するものである。 A first aspect of the present invention includes a refractive index matching liquid tank containing a refractive index matching liquid, a preform rod immersed in the refractive index matching liquid and having a refractive index distribution therein, and a refractive index matching liquid tank. An image projection device arranged outside and projecting an image, and a preform rod immersed in a refractive index matching liquid and the image projection device on the same optical axis and opposite the image projection device with the preform rod in between Is obtained by this imaging by using a camera to project a projection image that has passed through a preform rod immersed in a refractive index matching liquid. In the method of analyzing the received light data of the two-dimensional array and measuring the refractive index distribution of the preform rod, the projected image passing through the preform rod immersed in the refractive index matching liquid is captured by the camera. By imaging several times to output the light reception data of each two-dimensional array, in order to reduce variations in the value of the light receiving data, the two-dimensional array of the respective light receiving data, a plurality of which is divided between black and white in multiple stages The data is composed of blocks and is superposed at each block position. The superposed data is processed at each block position by at least one of an averaging process and a median value extraction process. The received light data is converted into one projected image data in which the number of blocks with different color shades indicating noise generated in the received light data is reduced from the two-dimensional array, and the preformed rod data is converted from the projected light image data. The refractive index distribution of the preform rod is measured by analyzing the amount of strain.
また、本発明の第２の態様は、屈折率整合液が収容された屈折率整合液槽と、屈折率整合液中に浸漬され内部に屈折率分布を有するプリフォームロッドと、屈折率整合液槽の外部に配置され画像を投影する画像投影装置と、屈折率整合液中に浸漬されたプリフォームロッド及び画像投影装置と同一光軸上で且つ当該プリフォームロッドを間にして画像投影装置と反対側に配置され、１次元配列の受光データを２次元配列の受光データにするために複数受けられたラインセンサカメラとからなる光学系により、屈折率整合液中に浸漬されたプリフォームロッドを通過してきた投光画像を複数のラインセンサカメラにより撮像し、この撮像により得られた２次元配列の受光データを解析してプリフォームロッドの屈折率分布を測定する方法において、屈折率整合液中に浸漬されたプリフォームロッドを通過してきた投光画像を複数受けられたラインセンサカメラで複数回撮像してそれぞれの２次元配列の受光データを出力し、各受光データの値のばらつきを小さくするために、当該各受光データの２次元配列を、白黒間を多段階に区分した複数のブロックから成るデータにしてそれぞれのブロック位置で重ね合わせ処理し、この重ね合わせ処理されたデータをそれぞれのブロック位置で平均化処理及びメジアン値抽出処理のうち少なくとも１つで処理することにより、当該各受光データを、２次元配列から当該受光データに生じた雑音を示す色の濃淡の異なるブロックの数を減少させた１つの投光画像データにして、当該１つの投光画像データからプリフォームロッドの歪み量を解析することでプリフォームロッドの前記屈折率分布を測定するものである。 Further, the second aspect of the present invention includes a refractive index matching liquid tank containing a refractive index matching liquid, a preform rod immersed in the refractive index matching liquid and having a refractive index distribution therein, and a refractive index matching liquid. An image projecting device arranged outside the bath for projecting an image, a preform rod immersed in a refractive index matching liquid, and the image projecting device on the same optical axis as the image projecting device and with the preform rod in between A preform rod immersed in a refractive index matching liquid is disposed by an optical system including a plurality of line sensor cameras arranged on the opposite side and received in order to convert the received light data of the one-dimensional array into the received light data of the two-dimensional array. In the method of measuring the refractive index distribution of a preform rod by capturing a projected image that has passed through a plurality of line sensor cameras and analyzing the received light data of the two-dimensional array obtained by the imaging. The plurality of projected images that have passed through the preform rod immersed in the refractive index matching liquid are picked up multiple times by the line sensor camera, and the received light data of each two-dimensional array is output. to reduce variations in the value, the two-dimensional array of the respective received light data, between black and white overlay treated with each of the blocks located in the data comprising a plurality of blocks obtained by dividing the multiple stages, processed this superposition By processing at least one of the averaging process and the median value extraction process at each block position, each received light data is converted into a shade of color indicating noise generated in the received light data from a two-dimensional array. One projection image data in which the number of different blocks is reduced, and the distortion amount of the preform rod is analyzed from the one projection image data. Which measures the refractive index profile of the preform rod by.
また、本発明の第３の態様は、屈折率整合液が収容された屈折率整合液槽と、屈折率整合液中に浸漬され内部に屈折率分布を有するプリフォームロッドと、屈折率整合液槽の外部に配置され画像を投影する画像投影装置と、屈折率整合液中に浸漬されたプリフォームロッド及び画像投影装置と同一光軸上で且つ当該プリフォームロッドを間にして画像投影装置と反対側に配置され、１次元配列の受光データにするラインセンサカメラと、ラインセンサカメラの撮像位置を変更する撮像位置変更機構とからなる光学系により、屈折率整合液中に浸漬されたプリフォームロッドを通過してきた投光画像をラインセンサカメラの撮像位置を撮像位置変更機構で変更しながら撮像して、１次元配列の受光データを２次元配列の受光データにし、この撮像により得られた２次元配列の受光データを解析してプリフォームロッドの屈折率分布を測定する方法において、屈折率整合液中に浸漬されたプリフォームロッドを通過してきた投光画像を、ラインセンサカメラ及び撮像位置変更機構で２次元配列の受光データを複数得るように撮像し、各受光データの値のばらつきを小さくするために、当該各受光データの２次元配列を、白黒間を多段階に区分した複数のブロックから成るデータにしてそれぞれのブロック位置で重ね合わせ処理し、この重ね合わせ処理されたデータをそれぞれのブロック位置で平均化処理及びメジアン値抽出処理のうち少なくとも１つで処理することにより、当該各受光データを、２次元配列から当該受光データに生じた雑音を示す色の濃淡の異なるブロックの数を減少させた１つの投光画像データにして、当該１つの投光画像データからプリフォームロッドの歪み量を解析することでプリフォームロッドの屈折率分布を測定するものである。
The third aspect of the present invention includes a refractive index matching liquid tank containing a refractive index matching liquid, a preform rod immersed in the refractive index matching liquid and having a refractive index distribution therein, and a refractive index matching liquid. An image projecting device arranged outside the bath for projecting an image, a preform rod immersed in a refractive index matching liquid, and the image projecting device on the same optical axis as the image projecting device and with the preform rod in between A preform placed on the opposite side and immersed in a refractive index matching liquid by an optical system comprising a line sensor camera for receiving light in a one-dimensional array and an imaging position changing mechanism for changing the imaging position of the line sensor camera. The projected image that has passed through the rod is captured while changing the imaging position of the line sensor camera with the imaging position changing mechanism, and the received light data of the one-dimensional array is converted into the received light data of the two-dimensional array. In the method of measuring the refractive index distribution of the preform rod by analyzing the received light data of the two-dimensional array obtained by the above, the projected image passing through the preform rod immersed in the refractive index matching liquid is converted into a line sensor. In order to reduce the variation in the value of each received light data, the two-dimensional array of each received light data is divided into multiple stages between black and white in order to obtain a plurality of received light data of a two-dimensional array with a camera and an imaging position changing mechanism. Data is composed of a plurality of divided blocks and is superimposed at each block position, and the superimposed data is processed at at least one of averaging processing and median value extraction processing at each block position. Reduces the number of blocks with different shades of color indicating noise generated in the received light data from the two-dimensional array. In the one projection image data that has, it is to measure the refractive index profile of the preform rod by analyzing the distortion of the preform rod from the one light projecting image data.
このような本発明の各態様によれば、２次元配列の受光データにするカメラで複数回撮像したり、１次元配列の受光データを２次元配列の受光データにするように構成されたラインセンサカメラで、当該２次元配列の受光データを複数得るように撮像したりすることで得られた複数の２次元配列の受光データを１つの投光画像データになるように雑音処理することから、その投光画像データの値は何度測定してもばらつきが非常に少なくなるので、繰り返し再現性がよくなる。 According to each aspect of the present invention as described above, a line sensor configured to capture a plurality of times with a camera that converts light reception data of a two-dimensional array, or converts light reception data of a one-dimensional array to light reception data of a two-dimensional array. Since the camera performs noise processing so that a plurality of light reception data of the two-dimensional array obtained by imaging so as to obtain a plurality of light reception data of the two-dimensional array becomes one light projection image data, Since the value of the projected image data is very small in variation no matter how many times it is measured, repeatability is improved.
本発明のプリフォームロッドの屈折率分布測定方法によれば、画像撮像装置で得られた複数の受光データを１つの投光画像データになるように雑音処理することから、その投光画像データの値は何度測定してもばらつきが非常に少なくなるので、内部に屈折率分布を有するプリフォームロッドの屈折率分布を測定する際、画像撮影装置から出力される受光データに雑音が発生しても高精度に測定できるようになる。 According to the refractive index distribution measuring method of the preform rod of the present invention, noise processing is performed so that a plurality of received light data obtained by the image pickup device become one projected image data. Since the variation is very small no matter how many times the value is measured, when measuring the refractive index distribution of a preform rod having a refractive index distribution inside, noise is generated in the received light data output from the image capturing device. Can be measured with high accuracy.
以下、本発明のプリフォームロッドの屈折率分布測定方法における好ましい実施の形態について、図面を参照して説明する。図１は本発明の屈折率分布測定方法が適用される測定装置の実施の一形態例である光学系を模式的に表した図である。 Hereinafter, a preferred embodiment of a method for measuring a refractive index distribution of a preform rod according to the present invention will be described with reference to the drawings. FIG. 1 is a diagram schematically showing an optical system as an embodiment of a measuring apparatus to which the refractive index distribution measuring method of the present invention is applied .
本発明の実施の一形態例である屈折率分布測定方法が適用される屈折率測定装置は図１に示すように、屈折率整合液２が収容された屈折率整合液槽３と、屈折率整合液中に浸漬され内部に屈折率分布を有する透明体である石英ガラスから成るプリフォームロッド４と、屈折率整合液槽３の外部に配置され画像を投影する画像投影装置５と、屈折率整合液中に浸漬されたプリフォームロッド４及び画像投影装置５と同一光軸上で且つ当該プリフォームロッド４を間にして画像投影装置５と反対側に配置された画像撮影装置６とを備えた光学系である。 A refractive index measuring apparatus to which a refractive index distribution measuring method according to an embodiment of the present invention is applied includes a refractive index matching liquid tank 3 containing a refractive index matching liquid 2, and a refractive index as shown in FIG. A preform rod 4 made of quartz glass that is immersed in the matching liquid and has a refractive index distribution inside, a preform rod 4 made of quartz glass, an image projecting device 5 that is arranged outside the refractive index matching liquid tank 3 and projects an image, and a refractive index. An image photographing device 6 disposed on the same optical axis as the preform rod 4 and the image projecting device 5 immersed in the matching liquid and on the opposite side of the image projecting device 5 with the preform rod 4 interposed therebetween. Optical system.
屈折率整合液槽３は、画像投影装置５からの投光画像の情報が画像撮影装置６にまで到達できるように透明な材質で形成させるか、あるいは画像投影装置５から画像撮影装置６までの光軸上においてプリフォームロッド４の屈折率分布の測定に必要な範囲に透明の材質から成る窓３１を設けるとよい。また、屈折率整合液槽３は、収容された屈折率整合液２にプリフォームロッド４を所定位置まで浸漬してその位置に固定する固定機構（図示せず）を有している。この固定機構としては、モータ等で制御される１軸の自動ステージ等が好適である。また、屈折率整合液２は屈折率分布を求めるべきプリフォームロッド４とその周囲の空気との屈折率差に起因する損失を少なくし、より測定精度を向上させるために使用するものである。 The refractive index matching liquid tank 3 is formed of a transparent material so that the information of the projected image from the image projection device 5 can reach the image photographing device 6, or from the image projecting device 5 to the image photographing device 6. A window 31 made of a transparent material may be provided in a range necessary for measuring the refractive index distribution of the preform rod 4 on the optical axis. Further, the refractive index matching liquid tank 3 has a fixing mechanism (not shown) for immersing the preform rod 4 in a stored refractive index matching liquid 2 to a predetermined position and fixing the preform rod 4 to that position. As this fixing mechanism, a one-axis automatic stage controlled by a motor or the like is suitable. The refractive index matching liquid 2 is used to reduce the loss due to the refractive index difference between the preform rod 4 whose refractive index distribution is to be obtained and the surrounding air, and to improve the measurement accuracy.
画像投影装置５は、画像と、画像の背後に当該画像を照明するための光源が設けられている（図示せず）。この画像としては、例えば直角三角形や二等辺三角形などの図柄の白黒２値画像が用いられる。 The image projection device 5 is provided with an image and a light source for illuminating the image behind the image (not shown). As this image, for example, a monochrome binary image having a design such as a right triangle or an isosceles triangle is used.
画像撮影装置６は、屈折率整合液中に浸漬されたプリフォームロッド４を通過してきた透過画像を複数回撮像する撮像手段である撮像素子６１と、撮像素子６１にはパーソナル・コンピュータ等から成る解析機器６２が接続されている。撮像素子６１の先端にはレンズ６３が設けられ、このレンズ６３には入射する光量の調整をするための絞り機構やフィルタが取り付けられていてもよい。解析機器６２は、撮像素子６１に接続され当該撮像素子６１で複数回撮像して得られたそれぞれの受光データに生じる雑音を除去することで１つの投光画像データを出力する雑音処理手段である雑音処理回路６２１と、雑音処理回路６２１に接続され当該雑音処理回路６２１から出力された投光画像データからプリフォームロッド４の歪み量を解析してプリフォームロッド４の屈折率分布を測定する屈折率分布測定手段である測定回路６２２とを備えている。この画像撮影装置６の撮像素子６１としては、撮像した投光画像を１次元配列の受光データにするラインセンサカメラ（ＣＣＤラインセンサカメラ等）や、撮像した投光画像を２次元配列の受光データにするカメラ（ＣＣＤカメラ等）等が好適である。また、画像撮影装置６の撮像素子６１がラインセンサカメラの場合は、ラインセンサカメラの１次元配列の受光データを２次元配列の受光データにするために、ラインセンサカメラである撮像素子６１の撮像位置を変更する撮像位置変更機構（図示せず）を備えてもよい。この撮像位置変更機構としては、モータ等で制御される微調整台等が好適である。 The image capturing device 6 includes an image sensor 61 that is an image capturing unit that captures a transmitted image that has passed through the preform rod 4 immersed in a refractive index matching liquid a plurality of times, and the image sensor 61 includes a personal computer or the like. An analysis device 62 is connected. A lens 63 is provided at the tip of the image sensor 61, and a diaphragm mechanism and a filter for adjusting the amount of incident light may be attached to the lens 63. The analysis device 62 is a noise processing unit that is connected to the image sensor 61 and outputs one light projection image data by removing noise generated in each light reception data obtained by imaging with the image sensor 61 a plurality of times. Refraction for measuring the refractive index distribution of the preform rod 4 by analyzing the distortion amount of the preform rod 4 from the noise processing circuit 621 and the projection image data output from the noise processing circuit 621 connected to the noise processing circuit 621 And a measurement circuit 622 which is a rate distribution measuring means. As the image pickup device 61 of the image photographing device 6, a line sensor camera (CCD line sensor camera or the like) that converts the picked-up projected image into a one-dimensional array of received light data or a two-dimensional array of received light data. A camera (such as a CCD camera) is suitable. When the image sensor 61 of the image capturing device 6 is a line sensor camera, the image sensor 61, which is a line sensor camera, captures the light received in the one-dimensional array of the line sensor camera. An imaging position changing mechanism (not shown) for changing the position may be provided. As this imaging position changing mechanism, a fine adjustment table controlled by a motor or the like is suitable.
また、解析機器６２が備えている雑音処理回路６２１は、例えば、各受光データを重ね合わせ処理と共に平均化処理及びメジアン値抽出処理のうち少なくとも１つの処理で雑音除去することで１つの投光画像データを生成する雑音処理機能を有している。 The noise processing circuit 621 included in the analysis device 62 removes noise by performing at least one of averaging processing and median value extraction processing together with superimposition processing, for example, by superimposing each received light data. It has a noise processing function to generate data.
例えば、各受光データを重ね合わせ処理、平均化処理して１つの投光画像データを生成する場合について図２に基づき説明する。受光データ、投光画像データを簡易的な数値モデルにするために、３×３マスの領域のデータとし、各ブロックに記入される白黒２値の明度の段階を０が一番暗く、７が一番明るくなる０〜７の８段階の数値に分けるものとする。また、画像撮影装置６の撮像素子６１で撮像する回数を３回とする。 For example, the case where each received light data is superimposed and averaged to generate one light projection image data will be described with reference to FIG. In order to make the received light data and the projected image data into a simple numerical model, it is assumed that 3 × 3 area data is used, and the brightness level of black and white binary values written in each block is 0, and 7 is the darkest. It is assumed to be divided into 8 levels from 0 to 7, which are the brightest. In addition, the number of times of imaging with the image sensor 61 of the image capturing device 6 is set to three.
１回目に撮像された投光画像の受光データは図２（ａ）に示すように、上段のブロックに記入される明度の数値が左側から「３、４、７」、中段のブロックに記入される明度の数値が左側から「６、１、３」、下段のブロックに記入される明度の数値が左側から「４、１、５」になるように構成されている。 As shown in Fig. 2 (a), the light reception data of the projected image captured at the first time is entered in the middle block with the lightness values entered in the upper block "3, 4, 7" from the left side. The brightness value is “6, 1, 3” from the left side, and the brightness value entered in the lower block is “4, 1, 5” from the left side.
２回目に撮像された投光画像の受光データは図２（ｂ）に示すように、上段のブロックに記入される明度の数値が左側から「６、７、２」、中段のブロックに記入される明度の数値が左側から「１、６、４」、下段のブロックに記入される明度の数値が左側から「７、３、２」となるように構成されている。 As shown in Fig. 2 (b), the light reception data of the projected image captured for the second time is entered in the middle block, with the lightness values entered in the upper block being "6, 7, 2" from the left side. The brightness value is “1, 6, 4” from the left side, and the brightness value entered in the lower block is “7, 3, 2” from the left side.
３回目に撮像された投光画像の受光データは図２（ｃ）に示すように、上段のブロックに記入される明度の数値が左側から「４、２、７」、中段のブロックに記入される明度の数値が左側から「３、４、４」、下段のブロックに記入される明度の数値が左側から「１、６、３」となるように構成されている。 As shown in FIG. 2 (c), the light reception data of the projected image captured for the third time is entered in the upper block, with the brightness value entered in the upper block being "4, 2, 7" from the left side. The brightness value is “3, 4, 4” from the left side, and the brightness value entered in the lower block is “1, 6, 3” from the left side.
この３回の結果をそれぞれのブロック位置で重ね合わせ処理すると、図２（ｄ）に示すように、上段のブロックに記入される明度の数値は左側から「１３、１３、１６」、中段のブロックに記入される明度の数値は左側から「１０、１１、１１」、下段のブロックに記入される明度の数値は左側から「１２、１０、１０」となる。 When these three results are overlaid at each block position, as shown in FIG. 2 (d), the brightness value entered in the upper block is "13, 13, 16" from the left, and the middle block The lightness values entered in the left column are “10, 11, 11” from the left, and the lightness values entered in the lower block are “12, 10, 10” from the left.
また、この重ね合わせ処理されたデータをそれぞれのブロック位置で平均化処理すると、図２（ｅ）に示すように、上段のブロックに記入される明度の数値は左側から「４、４、５」、中段のブロックに記入される明度の数値は左側から「３、４、４」、下段のブロックに記入される明度の数値は左側から「４、３、３」となる。 Further, when the superposed data is averaged at the respective block positions, as shown in FIG. 2 (e), the brightness value entered in the upper block is “4, 4, 5” from the left side. The brightness values entered in the middle block are “3, 4, 4” from the left, and the brightness values entered in the lower block are “4, 3, 3” from the left.
このように、重ね合わせ処理することで、各数値が１２に集まり、平均化処理することで各数値が４に集まることになる。即ち、投光画像を複数回撮像し、同じブロック（位置）の明度の数値を重ね合わせ処理することで雑音の影響が低減して求めたい明度のデータにすることができる。したがって、画像撮影装置６による撮像回数を多くして、その各受光データを重ね合わせ処理することでデータ精度が高くなる。なお、平均化処理してから重ね合わせ処理してもよい。 In this way, by performing the superimposition process, each numerical value is collected at 12, and by performing the averaging process, each numerical value is collected at 4. That is, the projected image is captured a plurality of times, and the brightness value of the same block (position) is overlaid, so that the influence of noise is reduced and the desired brightness data can be obtained. Therefore, the data accuracy is increased by increasing the number of times of imaging by the image capturing device 6 and superimposing the received light data. The superimposition process may be performed after the averaging process.
また、各受光データを移動平均法による処理で雑音処理してから重ね合わせ処理してもよく、また、重ね合わせ処理してから移動平均法による処理をしてもよい。この移動平均法による処理は例えば図３に示すように、受光データが、上段のブロックに記入される明度の数値が左側から「３、３、４」、中段のブロックに記入される明度の数値が左側から「３、７、４」、下段のブロックに記入される明度の数値が左側から「５、３、３」となるように構成されているとすると、雑音の最大値「７」を除く８箇所の数値を加算し、その加算値をデータ数で除算して平均値「４」を求めて、最大値「７」を平均値「４」に入れ替えるように変更設定する手法である。 In addition, each received light data may be subjected to noise processing by processing based on the moving average method and then superposed, or may be processed after superimposition processing. For example, as shown in FIG. 3, the moving average method is such that the received light data is “3, 3, 4” from the left as the lightness value written in the upper block, and the lightness value is written in the middle block. Is “3, 7, 4” from the left side, and the brightness value entered in the lower block is “5, 3, 3” from the left side, the maximum noise value “7” is This is a technique of adding the numerical values of the 8 places excluding and dividing the added value by the number of data to obtain the average value “4” and changing the maximum value “7” to the average value “4”.
また、各受光データをメジアン値抽出処理により雑音処理してから重ね合わせ処理してもよく、また、重ね合わせ処理してからメジアン値抽出処理をしてもよい。このメジアン値抽出処理は例えば図４に示すように、受光データが、上段のブロックに記入される明度の数値が左側から「３、３、４」、中段のブロックに記入される明度の数値が左側から「３、７、４」、下段のブロックに記入される明度の数値が左側から「５、３、３」となるように構成されているとすると、これら数値をソートし、その中心値「３」を雑音の最大値「７」と入れ替えるように変更設定する手法である。 Further, each received light data may be subjected to noise processing by median value extraction processing and then subjected to superimposition processing, or may be subjected to superposition processing and then median value extraction processing. In this median value extraction process, for example, as shown in FIG. 4, the received light data is “3, 3, 4” from the left, and the lightness value written in the middle block is the lightness value written in the upper block. Assuming that “3, 7, 4” from the left side and the brightness value entered in the lower block are “5, 3, 3” from the left side, these numbers are sorted and the center value is sorted. In this method, “3” is changed and set to replace the maximum noise value “7”.
また、解析機器６２が備えている測定回路６２２は、雑音処理回路６２１の雑音処理機能で生成された１つの投光画像データからプリフォームロッド４の歪み量を解析することでプリフォームロッド４の屈折率分布を測定する屈折率分布測定機能を有している。この屈折率分布測定機能は、雑音処理回路６２１の雑音処理機能で生成された１つの投光画像データからプリフォームロッド４の歪み量を求め、その歪み量を解析することにより偏向関数を求め、その偏向関数に基づいてプリフォームロッド４の屈折率分布を求めるように演算処理する機能である。この屈折率分布測定機能は、本願出願人が出願済の特開２０００−１２１４９９号公報に記載されている光ファイバ母材の内部屈折率測定法でもよい。 In addition, the measurement circuit 622 included in the analysis device 62 analyzes the amount of distortion of the preform rod 4 from one projection image data generated by the noise processing function of the noise processing circuit 621, so that the preform rod 4 It has a refractive index distribution measuring function for measuring the refractive index distribution. This refractive index distribution measurement function obtains a distortion amount of the preform rod 4 from one projection image data generated by the noise processing function of the noise processing circuit 621, and obtains a deflection function by analyzing the distortion amount. This is a function of performing arithmetic processing so as to obtain the refractive index distribution of the preform rod 4 based on the deflection function. This refractive index distribution measurement function may be an internal refractive index measurement method of an optical fiber preform described in Japanese Patent Application Laid-Open No. 2000-121499 filed by the applicant of the present application.
このように構成された屈折率測定装置１で屈折率整合液槽３の屈折率整合液２に浸漬されたプリフォームロッド４の屈折率分布測定方法について説明する。 A method for measuring the refractive index distribution of the preform rod 4 immersed in the refractive index matching liquid 2 of the refractive index matching liquid tank 3 using the refractive index measuring apparatus 1 configured as described above will be described.
まず、画像投影装置５から屈折率整合液槽３の屈折率整合液中に浸漬されたプリフォームロッド４に画像を投射する。このプリフォームロッド４を通過してきた投光画像を画像撮影装置６の撮像素子６１で複数回撮像する。この撮像素子６１で撮像した投光画像の１つの受光データは例えば図５に示すような画像になる。この画像の明るい部分の何れかの部位を抽出したものが図６（ａ）の左側に示したような画像になる。なお、便宜上、この部位に限定して説明するが、実際は図５に示す画像全体で画像処理が行なわれる。 First, an image is projected from the image projection device 5 onto the preform rod 4 immersed in the refractive index matching liquid in the refractive index matching liquid tank 3. The projected image that has passed through the preform rod 4 is captured a plurality of times by the image sensor 61 of the image capturing device 6. One received light data of the projected image captured by the image sensor 61 is, for example, an image as shown in FIG. An image obtained by extracting any one of the bright portions of the image is an image as shown on the left side of FIG. For convenience, the description will be limited to this part, but in practice, image processing is performed on the entire image shown in FIG.
図６（ａ）の左側に示す画像では雑音を示す色の濃淡の異なるブロックが多く点在している。この状態を図２に示す３×３マスの領域から成る簡易的な数値モデルにすると、図６（ａ）の右側に示したようなものになる。なお、各ブロックに記入される明度の段階は０が一番暗く、７が一番明るくなる０〜７の８段階の数値に分けるものとする。この場合は、上段のブロックに記入される明度の数値が左側から「３、４、７」、中段のブロックに記入される明度の数値が左側から「６、１、３」、下段のブロックに記入される明度の数値が左側から「４、０、５」となるように構成されている。 In the image shown on the left side of FIG. 6A, many blocks having different shades of color indicating noise are scattered. If this state is made into a simple numerical model composed of a 3 × 3 area shown in FIG. 2, it becomes as shown on the right side of FIG. The brightness level written in each block is divided into 8 levels from 0 to 7, with 0 being the darkest and 7 being the brightest. In this case, the lightness value entered in the upper block is “3, 4, 7” from the left, the lightness value entered in the middle block is “6, 1, 3” from the left, and the lower block. The brightness value to be entered is configured to be “4, 0, 5” from the left side.
このような受光データを解析機器６２の雑音処理回路６２１で重ね合わせ処理すると、図６（ｂ）の左側に示したような画像になる。この画像では図６（ａ）の左側に示した画像と比較すると、雑音を示す色の濃淡の異なるブロックの数が減少しているので、雑音が減少していることが確認できる。この状態を図６（ｂ）の右側に示したような３×３マスの領域から成る簡易的な数値モデルにすると、上段のブロックに記入される明度の数値が左側から「３、４、４」、中段のブロックに記入される明度の数値が左側から「３、２、３」、下段のブロックに記入される明度の数値が左側から「４、４、３」となるように構成されているので、図６（ａ）の右側に示したような数値モデルと比較すると、明度の数値がほぼ「３」か「４」になっている。 When such received light data is overlaid by the noise processing circuit 621 of the analysis device 62, an image as shown on the left side of FIG. In this image, as compared with the image shown on the left side of FIG. 6A, the number of blocks having different shades of color indicating noise is reduced, so that it can be confirmed that the noise is reduced. If this state is a simple numerical model consisting of a 3 × 3 square area as shown on the right side of FIG. 6B, the lightness values entered in the upper block are “3, 4, 4” from the left side. "The brightness value entered in the middle block is" 3, 2, 3 "from the left, and the brightness value entered in the lower block is" 4, 4, 3 "from the left. Therefore, compared with the numerical model as shown on the right side of FIG. 6A, the numerical value of the brightness is almost “3” or “4”.
このようにして雑音が除去された投光画像データから、解析機器６２の測定回路６２２でプリフォームロッド４の歪み量を求め、その歪み量を解析することにより偏向関数を求め、その偏向関数に基づいてプリフォームロッド４の屈折率分布を求めることができるので、プリフォームロッド４の屈折率分布を測定する際、撮像素子６１から出力される受光データに雑音が発生しても高精度に測定できるようになる。 From the projection image data from which noise has been removed in this way, the distortion amount of the preform rod 4 is obtained by the measurement circuit 622 of the analysis device 62, and the deflection function is obtained by analyzing the distortion amount. Since the refractive index distribution of the preform rod 4 can be obtained based on this, when the refractive index distribution of the preform rod 4 is measured, even if noise occurs in the received light data output from the image sensor 61, the measurement is performed with high accuracy. become able to.
なお、上述した本発明の屈折率分布測定方法が適用される測定装置においては、画像撮影装置６の撮像素子６１でプリフォームロッド４を通過してきた投光画像を複数回撮像して複数の受光データを得ていたが、これに限らず、画像撮影装置６に屈折率整合液中に浸漬されたプリフォームロッド４及び画像投影装置５と同一光軸上に配置され当該プリフォームロッド４を通過してきた投光画像を撮像する撮像素子６１を複数設けてもよい。 In the measuring apparatus to which the above-described refractive index distribution measuring method of the present invention is applied , the projected image that has passed through the preform rod 4 is captured a plurality of times by the image sensor 61 of the image capturing device 6 to receive a plurality of light. Although the data has been obtained, the present invention is not limited thereto, and the preform rod 4 immersed in the refractive index matching liquid in the image photographing device 6 and the image projection device 5 are arranged on the same optical axis and pass through the preform rod 4. A plurality of image pickup devices 61 for picking up the projected image thus obtained may be provided.
この複数の撮像素子６１で撮像した投光画像の各受光データは上述したような屈折率分布測定方法により測定される。即ち、画像投影装置５から画像を屈折率整合液槽３の屈折率整合液中に浸漬されたプリフォームロッド４を通過してきた投光画像を画像撮影装置６の各撮像素子６１で撮像してそれぞれの受光データを出力し、撮像素子毎の受光データを１つの投光画像データになるように雑音処理を行い、その雑音処理された投光画像データからプリフォームロッド４の歪み量を解析することで透明体の屈折率分布を測定することができる。したがって、プリフォームロッド４の屈折率分布を測定する際、撮像素子６１から出力される受光データに雑音が発生しても高精度に測定できるようになる。特に、画像撮影装置６の撮像素子６１が１次元配列の受光データにするラインセンサカメラの場合には、複数設けることで１次元配列の受光データを２次元配列の受光データにすることができるので、好適である。 Each received light data of the projected image captured by the plurality of image sensors 61 is measured by the refractive index distribution measuring method as described above. That is, an image projected from the image projection device 5 is picked up by the image pickup device 61 of the image photographing device 6 with a projected image passing through the preform rod 4 immersed in the refractive index matching liquid in the refractive index matching liquid tank 3. Each received light data is output, noise processing is performed so that the received light data for each image sensor becomes one projected image data, and the distortion amount of the preform rod 4 is analyzed from the projected image data subjected to the noise processing. Thus, the refractive index distribution of the transparent body can be measured. Therefore, when the refractive index distribution of the preform rod 4 is measured, even if noise occurs in the light reception data output from the image sensor 61, the measurement can be performed with high accuracy. In particular, in the case of a line sensor camera in which the image pickup device 61 of the image capturing device 6 uses a one-dimensional array of light reception data, a plurality of one-dimensional array of light reception data can be converted into a two-dimensional array of light reception data. Is preferable.
このようなプリフォームロッドの屈折率分布測定の実験を行なった。
［測定方法］
測定方法は、画像撮影装置に２次元配列の受光データにするカメラを使用し、そのカメラが有する撮像素子の１行ごとに撮影を行って連続撮影することで、最終的に２次元配列の受光データとした。また、測定回数は３０回にした。
［実施例１］
各受光データを重ね合わせ処理で雑音処理してプリフォームロッドの屈折率分布を測定した。
［比較例］
従来のように、雑音処理を行なわずにプリフォームロッドの屈折率分布を測定した。
An experiment for measuring the refractive index distribution of such a preform rod was conducted.
[Measuring method]
The measurement method uses a camera that converts the light reception data of the two-dimensional array to the image photographing device, and performs continuous photographing by photographing each row of the image sensor included in the camera, and finally the light reception of the two-dimensional array. Data. The number of measurements was 30.
[Example 1]
Each received light data was subjected to noise processing by overlay processing, and the refractive index distribution of the preform rod was measured.
[Comparative example]
As before, the refractive index distribution of the preform rod was measured without noise treatment.
上記測定結果を表１に示す。 The measurement results are shown in Table 1.
表１において、実施例１においては３０回測定のばらつき幅の標準偏差が０．００００１６、屈折率が１、４７０４２、比較例においては３０回測定のばらつき幅の標準偏差が０．００００３９、屈折率が１、４７０４２となった。即ち、実施例１の標準偏差は比較例の標準偏差の半分以下になっているので、繰り返し測定による測定再現性が格段に向上したことが確認できた。
In Table 1, in Example 1, the standard deviation of the variation width of 30 times measurement is 0.000016, the refractive index is 1,47042, and in the comparative example, the standard deviation of the variation width of 30 times measurement is 0.000039, the refractive index. Became 1,47042. That is, since the standard deviation of Example 1 was less than half of the standard deviation of the comparative example, it was confirmed that the measurement reproducibility by repeated measurement was remarkably improved.
なお、上述した本発明の実施例においては、石英ガラスからなるプリフォームロッドを具体例にして説明したが、これに限らず、内部に屈折率分布を有する透明体ならばどのようなものにでも適用でき、例えばプラスチック体のようなものを測定する場合にも適用可能である。 In the embodiment of the present invention described above, the preform rod made of quartz glass has been described as a specific example. However, the present invention is not limited to this, and any transparent body having a refractive index distribution inside may be used. For example, the present invention can also be applied to measuring a plastic body.
１……屈折率測定装置
２……屈折率整合液
３……屈折率整合液槽
４……プリフォームロッド（透明体）
５……画像投影装置
６……画像撮影装置
６１……撮像素子（撮像手段）
６２１……雑音処理回路（雑音処理手段）
６２２……測定回路（屈折率分布測定手段）
DESCRIPTION OF SYMBOLS 1 ... Refractive index measuring device 2 ... Refractive index matching liquid 3 ... Refractive index matching liquid tank 4 ... Preform rod (transparent body)
5 …… Image projection device 6 …… Image shooting device 61 …… Image sensor (imaging means)
621... Noise processing circuit (noise processing means)
622 ... Measuring circuit (refractive index distribution measuring means)
Claims (3)
前記屈折率整合液中に浸漬された前記プリフォームロッドを通過してきた前記投光画像を前記カメラで複数回撮像してそれぞれの前記２次元配列の受光データを出力し、前記各受光データの値のばらつきを小さくするために、当該各受光データの前記２次元配列を、白黒間を多段階に区分した複数のブロックから成るデータにしてそれぞれのブロック位置で重ね合わせ処理し、前記重ね合わせ処理されたデータをそれぞれのブロック位置で平均化処理及びメジアン値抽出処理のうち少なくとも１つで処理することにより、当該各受光データを、前記２次元配列から当該受光データに生じた雑音を示す色の濃淡の異なるブロックの数を減少させた１つの投光画像データにして、当該１つの投光画像データから前記プリフォームロッドの歪み量を解析することで前記プリフォームロッドの前記屈折率分布を測定することを特徴とするプリフォームロッドの屈折率分布測定方法。 A refractive index matching liquid tank containing a refractive index matching liquid, a preform rod immersed in the refractive index matching liquid and having a refractive index distribution therein, and an image disposed outside the refractive index matching liquid tank is projected. The image projection device, the preform rod immersed in the refractive index matching liquid, and the image projection device on the same optical axis and on the opposite side of the image projection device with the preform rod in between. A projected image passing through the preform rod immersed in the refractive index matching liquid is picked up by the camera by an optical system including a camera for receiving light in a two-dimensional array, and is obtained by this imaging. In the method of measuring the refractive index distribution of the preform rod by analyzing the received light data of the two-dimensional array,
The light projection image that has passed through the preform rod immersed in the refractive index matching liquid is imaged a plurality of times by the camera, and the light reception data of each two-dimensional array is output. to reduce the variation of the two-dimensional array of the respective received light data, and the data composed of a plurality of blocks obtained by dividing the inter monochrome multi-step processes superposition at each block position, is the superimposition process By processing at least one of the averaging process and the median value extraction process at each block position, the received light data is converted into a shade of color indicating noise generated in the received light data from the two-dimensional array. One projection image data in which the number of different blocks is reduced, and the amount of distortion of the preform rod is calculated from the one projection image data. Refractive index distribution measuring method of the preform rod and measuring the refractive index distribution of the preform rod by analysis.
前記屈折率整合液中に浸漬された前記プリフォームロッドを通過してきた前記投光画像を前記複数受けられたラインセンサカメラで複数回撮像してそれぞれの前記２次元配列の受光データを出力し、前記各受光データの値のばらつきを小さくするために、当該各受光データの前記２次元配列を、白黒間を多段階に区分した複数のブロックから成るデータにしてそれぞれのブロック位置で重ね合わせ処理し、前記重ね合わせ処理されたデータをそれぞれのブロック位置で平均化処理及びメジアン値抽出処理のうち少なくとも１つで処理することにより、当該各受光データを、前記２次元配列から当該受光データに生じた雑音を示す色の濃淡の異なるブロックの数を減少させた１つの投光画像データにして、当該１つの投光画像データから前記プリフォームロッドの歪み量を解析することで前記プリフォームロッドの前記屈折率分布を測定することを特徴とするプリフォームロッドの屈折率分布測定方法。 A refractive index matching liquid tank containing a refractive index matching liquid, a preform rod immersed in the refractive index matching liquid and having a refractive index distribution therein, and an image disposed outside the refractive index matching liquid tank is projected. The image projection device, the preform rod immersed in the refractive index matching liquid, and the image projection device on the same optical axis and on the opposite side of the image projection device with the preform rod in between. Passed through the preform rod immersed in the refractive index matching liquid by an optical system comprising a plurality of line sensor cameras received in order to convert the received light data of the one-dimensional array into the received light data of the two-dimensional array The projected image is captured by the plurality of line sensor cameras, and the received light data of the two-dimensional array obtained by the imaging is analyzed to measure the refractive index distribution of the preform rod. A method of,
The projected image that has passed through the preform rod immersed in the refractive index matching liquid is imaged a plurality of times by the received line sensor camera, and the received light data of each of the two-dimensional arrays is output. In order to reduce the variation in the value of each received light data, the two-dimensional array of the received light data is converted into data composed of a plurality of blocks in which black and white are divided in multiple stages, and is superposed at each block position. Each of the received light data is generated from the two-dimensional array to the received light data by processing the superposed data at at least one of an averaging process and a median value extracting process at each block position . One projection image data in which the number of blocks having different shades of color indicating noise is reduced, and the projection image data is obtained from the one projection image data. Refractive index distribution measuring method of the preform rod and measuring the refractive index distribution of the preform rod by analyzing the distortion of the form rods.
前記屈折率整合液中に浸漬された前記プリフォームロッドを通過してきた前記投光画像を、前記ラインセンサカメラ及び前記撮像位置変更機構で前記２次元配列の受光データを複数得るように撮像し、前記各受光データの値のばらつきを小さくするために、当該各受光データの前記２次元配列を、白黒間を多段階に区分した複数のブロックから成るデータにしてそれぞれのブロック位置で重ね合わせ処理し、前記重ね合わせ処理されたデータをそれぞれのブロック位置で平均化処理及びメジアン値抽出処理のうち少なくとも１つで処理することにより、当該各受光データを、前記２次元配列から当該受光データに生じた雑音を示す色の濃淡の異なるブロックの数を減少させた１つの投光画像データにして、当該１つの投光画像データから前記プリフォームロッドの歪み量を解析することで前記プリフォームロッドの前記屈折率分布を測定することを特徴とするプリフォームロッドの屈折率分布測定方法。 A refractive index matching liquid tank containing a refractive index matching liquid, a preform rod immersed in the refractive index matching liquid and having a refractive index distribution therein, and an image disposed outside the refractive index matching liquid tank is projected. The image projection device, the preform rod immersed in the refractive index matching liquid, and the image projection device on the same optical axis and on the opposite side of the image projection device with the preform rod in between. The preform rod immersed in the refractive index matching liquid is obtained by an optical system including a line sensor camera for receiving light in a one-dimensional array and an imaging position changing mechanism for changing the imaging position of the line sensor camera. The projected light image that has passed is imaged while the imaging position of the line sensor camera is changed by the imaging position changing mechanism, and the received light data of the one-dimensional array is two-dimensionally arrayed. In the method and the light receiving data, to measure the refractive index profile of the preform rod by analyzing the received light data of the two-dimensional array obtained by the imaging,
Imaging the projected image that has passed through the preform rod immersed in the refractive index matching liquid so as to obtain a plurality of light reception data of the two-dimensional array by the line sensor camera and the imaging position changing mechanism, In order to reduce the variation in the value of each received light data, the two-dimensional array of the received light data is converted into data composed of a plurality of blocks in which black and white are divided in multiple stages, and is superposed at each block position. Each of the received light data is generated from the two-dimensional array to the received light data by processing the superposed data at at least one of an averaging process and a median value extracting process at each block position . One projection image data in which the number of blocks having different shades of color indicating noise is reduced, and the one projection image data is used as the projection image data. Refractive index distribution measuring method of the preform rod and measuring the refractive index distribution of the preform rod by analyzing the distortion amount of remodeling rod.
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| JP5800174B2 (en) * | 2011-01-12 | 2015-10-28 | 国立研究開発法人宇宙航空研究開発機構 | Visualization method and apparatus of density gradient |
| KR101321409B1 (en) | 2012-01-12 | 2013-10-23 | (주)미토스 | Refractive index measuring method for plastic lens with curvature |
| RU2563310C2 (en) * | 2014-01-09 | 2015-09-20 | Акционерное общество "Швабе-Технологическая лаборатория" (АО "Швабе - Технологическая лаборатория") | Measuring method of average light dispersion and device for its implementation |
| CN112782120B (en) * | 2021-01-28 | 2021-11-26 | 清华大学 | Method and device for measuring refractive index of transparent solid with convex cambered surface |
| CN114739627B (en) * | 2022-03-16 | 2023-07-21 | 中国农业大学 | Optical matching calibration method and device for internal flow field of complex structure |
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| JP2792517B2 (en) * | 1988-06-03 | 1998-09-03 | 大日本印刷株式会社 | Sample inspection method |
| JP2947418B2 (en) * | 1990-08-11 | 1999-09-13 | 株式会社フジクラ | Measurement method of refractive index distribution of optical fiber base material |
| JPH11153517A (en) * | 1997-09-19 | 1999-06-08 | Dainippon Printing Co Ltd | Apparatus and method for visual inspection of defect of barrier rib of plasma display panel back plate |
| JP3072986B2 (en) * | 1998-10-12 | 2000-08-07 | 佐々木 一正 | Measurement method and measuring device for internal refractive index distribution of optical fiber preform |
| JP2000321168A (en) * | 1999-05-12 | 2000-11-24 | Fuji Photo Film Co Ltd | Inspection machine for density irregularity of beltlike running body |
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