Iec 61300 3 17 1999

Microsoft Word 1300 3 17f w97 doc NORME INTERNATIONALE CEI IEC INTERNATIONAL STANDARD 61300 3 17 Deuxième édition Second edition 1999 09 Dispositifs d''''interconnexion et composants passifs à fibres opt[.]

Domaine d'application et objet

L'objet de la présente partie de la CEI 61300 est de définir des méthodes permettant de mesurer l'angle de la face terminale des embouts polis angulairement convexes ou plats.

Méthode 1 – Méthode interférométrique automatique

Etant donné sa plus grande précision, la méthode 1 est considérée comme la méthode de référence.

Dans cette méthode, la face terminale de l'embout est placée dans un micropositionneur inclinable sous un microscope à capacité interférométrique.

A fixed support at the nominal value of the angle to be measured can be utilized; however, in this scenario, the described alignment procedure is not applicable It is essential to use a reference angle gauge measured through alternative methods.

Figure 2 – Exemple de montage de mesure de l'angle au moyen de l'interféromètre

Des différences de phase entre le front d'onde de référence et le front d'onde de la surface de l'embout en essai créent une zone de franges.

The tip is oriented by the micropositioner to the nominal value θ₀ of the angle to be measured For polished convex tips, the radius of curvature R and the apex offset component in the angle direction Eₓ are determined through the analysis of the interferometric zone The angle value is then assessed based on the measurements of R and Eₓ.

Centre de franges (sommet de polissage)

Figure 3 – Exemple de zone d'interférence d'un embout poli convexe

LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU.

Four methods are described for measuring the ferrule endface angle:

– method 1: automatic interferometric method (reference method);

Due to its greater accuracy, method 1 is considered to be the reference method.

In this method, the ferrule endface is placed in a tiltable micropositioner under a microscope with interferometric capability.

A fixed holder set at the nominal angle for measurement can be utilized; however, this approach does not allow for the alignment procedure previously described Instead, it is essential to employ a reference angled plug that has been measured using alternative methods.

Figure 2 – Example of set-up of angle measurement by means of interferometer

Phase differences between the reference wavefront and the wavefront from the surface of the ferrule under test create a fringe pattern.

The ferrule is adjusted to a nominal angle θ₀ using a micropositioner For a convex polished ferrule, the curvature radius R and the apex offset component in the direction of the angle Eₓ are determined through the analysis of the interferometric pattern The angle is then calculated based on the measurements of R and Eₓ.

Figure 3 – Example of interference pattern of a convex polished ferrule

For a flat polished tip, the angle is determined by the frequency of the interference fringes in the direction of the angle, which is based on the number of waves per unit length, represented as $1/\Lambda$.

Figure 4 – Exemple de zone d'interférence d'un embout poli plat

Méthode 2 – Méthode interférométrique manuelle

In this method, the terminal face of the tip is positioned in an adjustable micropositioner under an interferometric microscope The tip is tilted until the terminal face is perpendicular to the optical axis of the interferometer, indicating the accurate angle has been achieved For a polished convex tip, this alignment occurs when the interference rings and the fiber are symmetrical to the rotation axis Conversely, for a flat polished tip, the correct position is reached when the interference fringes vanish or reach a minimal count.

Franges interférométriques Centre de franges

Figure 5 – Exemple de zone d'interférence d'un embout poli convexe réglé pour la mesure de la méthode 2

L'angle de la face terminale de l'embout peut être lu sur le cadran du micropositionneur.

Méthode 3 – Méthode du profilomètre mécanique

Dans cette méthode, l'angle de la face terminale est évalué en profilant l'embout de la face terminale avec l'analyseur de surface.

The probe is mounted in a fixed support beneath a mechanical profilometer The probe's axis must be parallel to the stylus axis, and the tip should be positioned at an angle aligned with the direction of the stylus sweep.

L'angle de la face terminale de l'embout est évalué à partir de l'analyse du profil acquis. Λ

The angle of a flat polished ferrule is determined by analyzing the frequency of the interferometric fringes in the angle direction, which corresponds to the number of waves per unit length.

Figure 4 – Example of interference pattern of a flat polished ferrule

In this method, the ferrule endface is positioned in a tiltable micropositioner beneath a microscope equipped with interferometric capabilities The ferrule is adjusted until its surface is perpendicular to the optical axis of the interferometer, achieving the correct angle For a convex polished ferrule endface, this alignment is indicated by symmetrical interference rings and fiber around the rotation axis Conversely, for a flat polished ferrule, the optimal position is identified when the interference fringes vanish or are minimized.

Figure 5 – Example of interference pattern of a convex polished ferrule adjusted for method 2 measurement

The endface angle of the ferrule can be read at the dial of the micropositioner.

In this method, the endface angle is evaluated by profiling the endface ferrule with a surface analyser.

The ferrule is securely positioned in a fixed holder beneath the stylus of a mechanical profilometer It is essential that the ferrule axis remains parallel to the stylus axis, with the plug oriented at an angle that aligns with the direction of the stylus scan.

The endface angle of the ferrule is evaluated from the analysis of the acquired profile. Λ

Méthode 4 – Méthode de la lumière réfléchie

In this method, a visible He-Ne light beam is aligned along the axis of the tip, reflected by the tip's terminal face, and directed towards a screen where an energy zone is formed The screen is positioned perpendicular to the tip's axis and extends around it.

Rainure en V ou manchon de précision

NOTE – Pour des embouts polis convexes, une longueur appropriée L peut se situer entre 20 cm et 50 cm et peut être enregistrée dans le cadre des résultats d'essai.

Figure 6 – Exemple de montage pour la mesure de l'angle de la face terminale de l'embout

In the case of a flat-polished terminal face, the energy zone typically appears as a small, uniformly illuminated circle, characterized by minimal additional divergence from the laser beam Conversely, for a spherically polished terminal face, the captured image usually manifests as a small ring (Airy disk) at the center of a larger visible circle, which is formed by a beam that has diverged from the original laser beam This small ring results from the Fraunhofer diffraction of the He-Ne beam reflected by the spherical terminal face, which contains a fiber or a fiber hole as the central opening.

Embout poli plat Embout poli convexe

The terminal face angle of the tip q is determined by measuring the deviation angle of the He-Ne beam at the center of the visible circle or the energy zone ring while rotating the tip around its axis.

The resolution of the reflected beam is influenced by the finish level of the terminal face surface of the tip This surface must be polished to a degree that allows for a well-defined specular reflection of the He-Ne beam.

Cette méthode ne doit s'appliquer qu'aux embouts polis plats.

This method utilizes a visible light He-Ne beam aligned with the ferrule axis, which reflects off the ferrule endface to create a spot pattern on a surrounding screen that is perpendicular to the ferrule axis.

He-Ne laser V-groove or precision sleeve

NOTE – For convex polished ferrules, a suitable length L may be between 20 cm and 50 cm and may be recorded in the test result.

Figure 6 – Example of set-up for ferrule endface angle measurement

A flatly polished ferrule endface produces a small, uniformly illuminated circle with minimal laser beam divergence, while a spherically polished ferrule endface results in a small ring pattern.

The Airy disk appears at the center of a large visible circle formed by the divergence of the original laser beam This small ring is a result of Fraunhofer diffraction from the He-Ne beam that is reflected off the spherical ferrule endface, which contains a fiber or fiber hole acting as a centrally located aperture.

Flat polished ferrule Convex polished ferrule

The ferrule endface angle $ q $ is established by assessing the deviation angle of the He-Ne beam in relation to the center of the visible circle or ring of the spot pattern, as the ferrule is rotated around its axis.

The resolution of the reflected beam is influenced by the surface finish of the ferrule endface, which must be polished adequately to achieve a clear and well-defined specular reflection.

This method shall be applicable only on flat polished ferrules.

Pour la méthode 1, un appareillage est présenté à la figure 8, il se compose des éléments suivants:

Moniteur destiné à visualiser l’image Micropositionneur angulaire

Figure 8 – Exemple d'appareillage pour la mesure de l'angle au moyen de la méthode 1 a) Microscope

Microscope à capacité interférométrique associé à une caméra vidéo pour l'acquisition de l'image. b) Micropositionneur angulaire

Micropositionneur angulaire avec une résolution supérieure à 0,01°. c) Support d'embout

Support adapté tel qu'une rainure en V ou un manchon de précision pour maintenir l'embout selon une position fixe. d) Support de fiche

Dispositif mécanique capable de maintenir la fiche de manière que la clavette correspondante se situe dans la position exacte selon la direction nominale d'angle. e) Analyseur d'image

The analysis system is designed to assess the curvature radius of the interferometric image, as well as the dome shift component along the angle direction From these measurements, the angle value can be determined using equation (1).

Le moniteur doit afficher la surface mesurée avec la zone interférométrique.

L'appareillage est le même que celui-ci qui est présenté à la figure 8 pour la méthode 1.

S'agissant de la méthode 2, l'appareillage est composé des éléments suivants: a) Microscope

Microscope à capacité interférométrique associé à une caméra vidéo pour l'acquisition d'image. b) Micropositionneur angulaire

For method 1, an apparatus as shown in figure 8 consists of the following elements:

Monitor to view the image Angular micropositioner

Computer for the image analysis

Figure 8 – Example of apparatus for the angle measurement by method 1 a) Microscope

A microscope with interferometric capability associated with a video camera for image acquisition. b) Angular micropositioner

An angular micropositioner with a resolution better than 0,01°. c) Ferrule holder

A suitable fixture such as a V-groove or a precision alignment sleeve to hold the ferrule in a fixed position. d) Plug holder

A mechanical fixture able to hold the plug such that the relevant key lies in the exact position in respect to the nominal angle direction. e) Image analyser

An analysis system is designed to assess the interferometric image by determining the curvature radius and the dome offset component in the angular direction From these measurements, it calculates the angle using a specific formula.

The monitor shall display the measured surface with the interferometric pattern.

The apparatus is the same as shown in figure 8 for method 1 For method 2, the apparatus consists of the following elements: a) Microscope

An angular micropositioner with a resolution better than 0,01°.

LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU. c) Support d'embout

Dispositif adapté, tel qu'une rainure en V ou un manchon d'alignement de précision pour maintenir l'embout dans une position verticale fixe. d) Support de fiche

A mechanical device is designed to hold the plug in such a way that the corresponding key is positioned precisely in relation to the nominal angle direction Additionally, a monitor is intended for visual analysis.

The monitor is designed to control the surface of the workpiece using the interferometric zone during the adjustment of the relative position between the surface and the interferometric image, achieved by displacing the micropositioner.

L'appareillage est présenté à la figure 9 Les parties du composant sont décrites comme suit:

Unité de translation Extrémité de ciseau

DE DONNÉES Etage de positionnement

Figure 9 – Exemple de montage pour la mesure de l'angle de la face terminale de l'embout au moyen d'un profilomètre mécanique a) Support d'embout

Dispositif adapté, tel qu'une rainure en V ou un manchon d'alignement de précision pour maintenir l'embout dans une position verticale fixe. b) Support de fiche

A mechanical device is designed to hold the plug in such a way that the corresponding key is positioned precisely in relation to the nominal angle direction This is part of the positioning stage.

Dispositif mécanique assurant une fixation rigide du support d'embout et capable de le déplacer selon des positions appropriées. d) Analyseur de surface bidimensionnel

Analyseur de surface capable de mesurer le profil de la face terminale de l'embout en deux dimensions avec une précision de l'ordre de plusieurs nanomètres.

LICENSED TO MECON Limited - RANCHI/BANGALORE FOR INTERNAL USE AT THIS LOCATION ONLY, SUPPLIED BY BOOK SUPPLY BUREAU. c) Ferrule holder

A suitable fixture such as a V-groove or a precision alignment sleeve to hold the ferrule in a fixed vertical position. d) Plug holder

A mechanical fixture able to hold the plug such that the relevant key lies in the exact position in respect to the nominal angle direction. e) Monitor for visual analysis

A monitor is used to control the ferrule surface by displaying the interferometric pattern, facilitating the adjustment of the relative position between the interferometric image and the surface through the movement of the micropositioner.

The apparatus is shown in figure 9 The component parts are described as follows:

DATA PROCESSING UNIT Positioning stage

Figure 9 – Example of set-up for the measurement of the ferrule endface angle by a mechanical profilometer a) Ferrule holder

A suitable fixture such as a V-groove or a precision alignment sleeve to hold the ferrule in a fixed vertical position. b) Plug holder

A mechanical fixture able to hold the plug such a way that the relevant key lies in the exact position in respect to the nominal angle direction. c) Positioning stage

A mechanical device rigidly fixing the ferrule holder and able to move it at appropriate positions. d) Two-dimensional surface analyser

A surface analyser able to measure the profile of the ferrule endface in two dimensions with an accuracy in the order of several nanometers.

The analyzer must include a profilometer, a profile data processing unit, and a monitor The profilometer should be equipped with a wedge-type probe positioned so that the trace movement is perpendicular to the tip axis, along with a translation stage and an electronic interface unit that connects the measurement system to the data processing unit (such as a computer with suitable software), providing input and output data: movement commands and profile data The profile data processing must be capable of processing profile data and calculating the terminal face angle using an appropriate algorithm The monitor should display the measurement data.

Rainure en V ou manchon d'alignement de précision (selon l’ISO 2538, l'angle préférentiel pour une rainure en V est de 108°). b) Ecran

Ecran perpendiculaire à l'axe de la rainure en V ou du manchon de précision. c) Laser He-Ne

The He-Ne laser beam is aligned to coincide with the axis of the V-groove or precision sleeve, ensuring that it strikes the terminal face of the fitting directly.

To ensure accurate measurements, first, place the non-angular reference tip in the holder connected to the angular micropositioner, ensuring that the eccentricity from polishing is less than 5 µm and the curvature radius exceeds 25 mm Next, position the micropositioner under an interferometric microscope, aligning the reference tip's axis parallel to the microscope's optical axis Carefully adjust the micropositioner's angle until the interference rings and the reference tip's fiber are symmetrical along a straight line parallel to the rotation axis Record the micropositioner's dial angle, which will serve as the reference value Then, insert the sample into the measurement holder associated with the angular micropositioner and set the micropositioner to the nominal angle θ₀ based on the reference position obtained earlier Finally, derive the angle value from the interference image.

1) Pour les embouts polis convexes

The curvature radius value $ R $ of the polishing surface must be assessed through an adaptation procedure The adaptation region is defined by an annular area with an outer diameter $ D $ and an inner diameter $ E $, centered around the axis of the tip The diameters $ D $ and $ E $ should be specified in the particular specifications, with preferred values of $ D = 250 \, \mu m $ and $ E = 140 \, \mu m $ for APC connectors with a nominal fiber diameter of $ 125 \, \mu m $.

12 mm de rayon de courbure des faces terminales des embouts polis angulairement.

Based on the image analysis, it is essential to measure the component in the direction of angle E x, which represents the distance between the center of the interferometric rings and the tip's core (refer to Figure 3) The angle value should be expressed as follows: \$x_0 = \arctan(\theta) + \theta\$.

The analyser shall consist of a profilometer, a profile data processing unit and a monitor.

The profilometer must feature a wedge-type probe positioned to ensure that the trace motion is perpendicular to the ferrule axis Additionally, it should include a translation stage and an electronic interface unit that connects the measuring system to the data processing unit.

A computer equipped with suitable software will process input and output data, including movement commands and profile data The system will utilize an appropriate algorithm to calculate the endface angle from the profile data, and the measured data will be displayed on the monitor.

3.4 Method 4 – Reflected light method a) Ferrule holder

A V-groove or precision alignment sleeve (according to ISO 2538, the preferred angle for a

A screen perpendicular to the axis of the V-groove or precision sleeve. c) He-Ne laser

A He-Ne laser whose beam is aligned to be coincident with the axis of the V-groove or precision sleeve and thus impinges on the endface of the ferrule.

The automatic interferometric method involves placing a non-angled reference ferrule in a holder connected to an angular micropositioner, ensuring that the eccentricity from the polishing of the reference ferrule is less than 5 µm.

The radius of curvature of the reference ferrule must exceed 25 mm Position the micropositioner beneath a microscope equipped with interferometric capabilities, ensuring the reference ferrule axis is aligned with the optical axis of the microscope Carefully adjust the micropositioner's angle until the interference rings and the fibre of the reference ferrule are symmetrical to a straight line parallel to the rotation axis Record the angle displayed on the micropositioner's dial, which serves as the reference value Next, place the sample in the measurement holder connected to the angular micropositioner and adjust the angle to the nominal angle θ0 based on the reference position obtained earlier Finally, derive the angle value from the interference image.

The curvature radius $ R $ of the polishing surface is evaluated through a fitting procedure within a defined ring-shaped region, characterized by an outer diameter $ D $ and an inner diameter $ E $, centered around the ferrule axis These diameters $ D $ and $ E $ will be specified in the detail specifications For APC connectors with a nominal fiber diameter of 125 µm, the preferred curvature radius for angled polished ferrule endfaces ranges from 5 mm to 12 mm.

The analysis of the image reveals that the distance between the center of the interferometric rings and the ferrule core is measured in the angle direction E x, with D set at 250 àm and E at 140 àm The angle can be calculated using the formula: \$\theta = \arctan\left(\frac{x}{D}\right)\$.

2) Pour les embouts polis à plat

Based on the image analysis, it is essential to assess the frequency of the interference fringes in the angular direction, as illustrated in Figure 3 This evaluation is determined by the number of waves per unit length, represented as $1/\Lambda$ The angle value should be as follows:

= × (2) ó λ est la longueur d'onde lumineuse utilisée pour éclairer l'embout en essai.

To begin, insert the non-angular reference tip into the holder connected to the angular micropositioner, ensuring that the eccentricity from polishing is less than 5 µm and the curvature radius exceeds 25 mm Next, position the micropositioner under the interferometric microscope, aligning the reference tip's axis parallel to the microscope's optical axis Carefully adjust the micropositioner's angle until the interference rings and the fiber of the reference tip appear symmetrical along a straight line parallel to the rotation axis Record the dial angle of the micropositioner, which will serve as the reference value Then, place the sample in the measurement holder associated with the angular micropositioner Adjust the micropositioner's angle so that the terminal face of the tip is perpendicular to the microscope's optical axis Finally, observe the interference zone of the terminal face image and fine-tune the micropositioner's angle accordingly.

1) Pour les embouts polis convexes, les anneaux d'interférence et la fibre soient symétriques à une ligne droite sur l'image qui est parallèle à l'axe de rotation;

For flat polished tips, interference fringes vanish, resulting in a uniformly intense image under the microscope Measure the angle using the micropositioner's dial The angle of the fiber's end face is determined by the difference between the value recorded in the previous measurement and the value obtained in the subsequent measurement.

To properly secure the connector pin in the plug and socket, ensure that the section of the pin closest to the terminal face is held within the socket The part of the pin in contact with the socket should be twice the diameter of the contact area Adjust the cutting edge of the profilometer so that its lower edge is perpendicular to the axis of the pin Finally, establish the coordinates of the fiber center within the profilometer's reference system.

Pre-calibrating the distance between the center of the fiber and the starting point of the trace ensures that this distance remains known and constant during various measurements As a result, the position of the fiber's center is consistently defined in relation to the reference system of the profilometer Additionally, adjust the positioning stage so that the profilometer's cutting edge is set at the starting point and crosses the axis of the tip.

The analysis of the image reveals the frequency of the interferometric fringes in the angular direction, as illustrated in Figure 3 This frequency, defined as the number of waves per unit length (1/Λ), will be evaluated to determine the angle's value.

= × (2) where λ is the light wavelength used to light the ferrule under test.

The manual interferometric method involves several key steps for accurate measurement First, securely place a non-angled reference ferrule in the holder of the angular micropositioner, ensuring its polishing eccentricity is less than 5 µm and its radius of curvature exceeds 25 mm Next, position the micropositioner under a microscope equipped with interferometric capabilities, aligning the reference ferrule's axis parallel to the optical axis Carefully adjust the micropositioner's angle until the interference rings and the fiber of the reference ferrule appear symmetrical along a straight line parallel to the rotation axis Record the angle displayed on the micropositioner dial, which serves as the reference value Subsequently, insert the sample into the measurement holder attached to the micropositioner and adjust its angle to ensure the ferrule's endface is perpendicular to the optical axis Finally, observe the interference pattern of the endface image and make fine adjustments to the micropositioner's angle for optimal results.

1) For convex polished ferrules, interference rings and fibre are symmetrical to a straight line on the image which is parallel to the rotation axis;

For flat polished ferrules, the interference fringes vanish, resulting in a microscope image with consistent intensity To determine the fibre endface angle, read the angle from the micropositioner's dial and subtract the value obtained from the previous measurement.

The mechanical profilometer method involves several key steps: First, securely attach the connector plug in the ferrule and plug holder, ensuring that the ferrule's endface is properly positioned, with the contact area length being twice its diameter Next, adjust the profilometer's chisel tip to ensure its bottom edge is perpendicular to the ferrule's axis Finally, establish the coordinates of the fiber center within the profilometer's reference system by precalibrating the distance from the fiber center to the trace start point.

To ensure accurate measurements, the known and constant distance is used to determine the position of the fiber center relative to the profilometer's reference system Additionally, it is essential to adjust the positioning stage so that the profilometer's chisel tip aligns with the starting point and passes through the ferrule's axis.

Licensed to MECON Limited in Ranchi/Bangalore for internal use only, supplied by Book Supply Bureau It is essential to execute a trace on the profilometer across the surface of the end of the nozzle for a distance of approximately 500 µm around the nozzle axis, and to record the profile data on the data processing unit This procedure applies specifically to polished convex nozzles.

The adaptation region of the connector's end face is defined as a ring-shaped area with an upper diameter D and a lower diameter E, centered around the connector's axis This region encompasses the contact zone of the end face when coupled, and the specific diameters must be detailed in the specifications For APC connectors with a nominal fiber diameter of 125 µm and end faces polished at an angular radius of curvature between 5 mm and 12 mm, the preferred values are D = 250 µm and E = 150 µm.

Figure 10 – Face terminale d'embout et région de mesure

2) Calculer un cercle idéal s'approchant de la région d'adaptation en utilisant la méthode des moindres carrés ou d'autres méthodes spécifiées, pour évaluer le rayon approprié

R et les coordonnées des C (le centre de la fibre: voir figure 11), DX et DZ en rapport avec le centre du cercle d'adaptation.

The profilometer should be operated to trace the ferrule end surface over a distance of approximately [insert distance here] This procedure is intended for internal use at the specified locations of MECON Limited in Ranchi and Bangalore, as supplied by the Book Supply Bureau.

500 àm around the ferrule axis; record the profile data on the data processing unit. f) For convex polished ferrules

The fitting region of the ferrule endface is characterized by a ring-shaped area defined by a higher diameter D and a lower diameter E, both centered around the ferrule's axis This region encompasses the contact zone of the ferrule endface during mating, with the specific diameters D and E outlined in the detailed specifications.

Preferred values for APC connectors with 125 àm nominal fibre diameter and 5 mm to

12 mm as curvature radius of angled polished ferrules endfaces are D = 250 àm and

Figure 10 – Ferrule endface and measurement region

To determine an ideal circle that closely fits the specified region, employ the least squares method or alternative techniques to calculate the relevant radius $ R $ and the coordinates of the fiber center $ C $ (refer to figure 11), along with the values of $ DX $ and $ DZ $ in relation to the center of the fitting circle.

Figure 11 – Représentation géométrique de l'algorithme de mesure

3) La valeur de l'angle doit être la suivante:

DX arctan arcsin θ (3) g) Pour l'embout poli à plat

Store the adaptation profile data based on the measurement profile data The adaptation region of the terminal face of the nozzle is defined by a ring-shaped area with an upper diameter D and a lower diameter E, centered around the nozzle axis.

2) Calculer une ligne droite idéale s'approchant de la région d'adaptation en utilisant la méthode des moindres carrés ou d'autres méthodes spécifiées La valeur de l'angle doit être:

( ) S arctan θ = (4) ó S est l'inclinaison de la ligne d'adaptation.

The accuracy of the measurement is influenced by the parallelism between the profilometer probe and the tip axis One way to verify this parallelism is by using an angularly polished tip with a known terminal face angle and checking the difference between the measured angle and the reference angle An alternative method involves measuring the angle, then repeating the measurement after rotating the tip by 180° It is important to consider this difference to correct the mechanical error of the probe.

Ligne droite tangente au coeur de la fibre

Figure 11 – Geometrical representation of the measurement algorithm

3) The value of the angle shall be:

DX arctan arcsin θ (3) g) For flat polished ferrules

The fitting region of the ferrule endface is characterized by a ring-shaped area defined by a higher diameter D and a lower diameter E, both centered around the ferrule's axis This profile data is crucial for accurate measurements and assessments.

2) Calculate an ideal straight line approximating the fitting region using the least squares method, or other specified methods The value of the angle shall be:

( ) S arctan θ = (4) where S is the slope of the fitting line.

To optimize the visibility of the energy zone on the screen, first, place the tip in the V-groove or precision sleeve and illuminate its terminal face with the He-Ne beam Adjust the tip's position for maximum visibility in the interference image, as illustrated in Figure 7 Rotate the tip 360° within the V-groove or precision sleeve, noting that the energy zone traces a concentric line along the target circle displayed on the screen Measure the diameter $D$ of the points forming the circle of the energy zone (refer to Figure 6) Finally, calculate the angle $q$ of the tip's terminal face using the diameter $D$ and the distance $L$ from the tip's terminal face to the screen, applying the appropriate equation.

The article discusses several key factors related to the terminal face angle of the tip, including the curvature radius of the reference tip, the magnification of the microscope used, and the eccentricity resulting from the polishing of the reference tip Additionally, it addresses the diameters D and E in the adaptation region, as well as the rotational tolerance of the tip's position within the support associated with the angular micropositioner.

The article discusses several key factors related to the terminal face of a tip, including the admissible angle of the tip's terminal face, the curvature radius of the reference tip, and the magnification of the microscope used It also addresses the eccentricity resulting from the polishing of the reference tip, the diameters D and E in the adaptation region, and the rotational tolerance of the tip's position within the support associated with the angular micropositioner.

The article discusses key aspects of profile acquisition, including the style type, form, and weight It outlines the specifications for the support of the tip and the support of the connector Additionally, it addresses the tolerance related to the positioning of the tip within the support, as well as the diameters D and E in the adaptation region The method for calculating the adaptation region and the coordinates DX and DZ is also detailed, along with the permissible angle of the terminal face of the tip.

The reflected light method involves several key steps for accurate measurement First, place the ferrule in the V-groove or precision sleeve and illuminate its endface with a He-Ne beam Next, observe the beam spot pattern on the screen, adjusting the ferrule's position to achieve maximum visibility of the interference pattern Rotate the ferrule 360° within the V-groove or precision sleeve, noting that the spot pattern will trace a concentric circle on the screen Measure the diameter $D$ of this circle locus, and use the following equation to calculate the ferrule endface angle $q$ based on the diameter $D$ and the distance $L$ from the ferrule endface to the screen.

The automatic interferometric method involves several key parameters: the allowable angle of the ferrule endface, the radius of curvature of the reference ferrule, and the magnification of the microscope objective used Additionally, it accounts for the eccentricity resulting from the polishing of the reference ferrule, the diameters D and E of the fitting region, and the rotational tolerance of the ferrule's position within the holder connected to the angular micro-positioner.

The manual interferometric method involves several key parameters: the allowable angle of the ferrule endface, the radius of curvature of the reference ferrule, and the magnification of the microscope objective used Additionally, it is important to consider the eccentricity resulting from the polishing of the reference ferrule, as well as the diameters D and E of the fitting region Lastly, the rotational tolerance of the ferrule position in the holder, which is attached to the angular micro-positioner, must also be accounted for.

The mechanical profilometer method involves several key considerations: the type of stylus, including its shape and weight during profile acquisition; specific requirements for the ferrule holder and plug holder; tolerance levels for ferrule positioning; the diameters D and E of the fitting region; a method for calculating the fitting region along with coordinates DX and DZ; and the allowable angle of the ferrule endface.

Scope and object

The object of this part of IEC 61300 is to describe the methods to measure the endface angle of flat or convex angle-polished ferrules.

Normative references

This section of IEC 61300 references several normative documents that are integral to its provisions For dated references, any amendments or revisions to these publications are not applicable However, parties involved in agreements related to IEC 61300 are encouraged to consider the latest editions of the referenced normative documents In the case of undated references, the most recent edition of the cited document is applicable Additionally, IEC and ISO members keep updated registers of valid International Standards.

ISO 2538:1998, Geometrical Product Specifications (GPS) – Series of angles and slopes on prisms

The ferrule endface angle θ is crucial in optical fiber connections, defined differently for flat and spherically polished ferrules For flat endface angle-polished ferrules, θ is the angle between the plane perpendicular to the ferrule's axis and the flat endface In contrast, for spherically polished angled endface ferrules, θ is measured between the perpendicular plane and the tangent line at the fiber core, aligned with the nominal angle.

Plane perpendicular to this fibre axis

Ferrule Fibre axis Fibre axis

Straight line tangent to the polished surface

Plane of the flat endface θ θ

Figure 1a – Convex polished ferrules Figure 1b – Flat polished ferrules

Figure 1 – Definition of ferrule endface angle for convex and flat polished ferrules

Quatre méthodes sont décrites pour la mesure de l'angle de la face terminale de l'embout:

– méthode 1: méthode interférométrique automatique (méthode de référence) ;

– méthode 3: méthode du profilomètre mécanique ;

– méthode 4: méthode de la lumière réfléchie.

Etant donné sa plus grande précision, la méthode 1 est considérée comme la méthode de référence.

Dans cette méthode, la face terminale de l'embout est placée dans un micropositionneur inclinable sous un microscope à capacité interférométrique.

A fixed support at the nominal value of the angle to be measured can be utilized; however, in this scenario, the alignment procedure outlined is not applicable It is essential to use a reference angle gauge measured through alternative methods.

Figure 2 – Exemple de montage de mesure de l'angle au moyen de l'interféromètre

Des différences de phase entre le front d'onde de référence et le front d'onde de la surface de l'embout en essai créent une zone de franges.

The tip is oriented by the micropositioner to the nominal value θ₀ of the angle to be measured For polished convex tips, the radius of curvature R and the apex offset component in the angle direction Eₓ are determined through the analysis of the interferometric zone The angle value is then assessed based on the measurements of R and Eₓ.

Centre de franges (sommet de polissage)

Figure 3 – Exemple de zone d'interférence d'un embout poli convexe

Four methods are described for measuring the ferrule endface angle:

– method 1: automatic interferometric method (reference method);

Method 1 – Automatic interferometric method

Due to its greater accuracy, method 1 is considered to be the reference method.

In this method, the ferrule endface is placed in a tiltable micropositioner under a microscope with interferometric capability.

A fixed holder set at the nominal angle can be utilized for measurement; however, this approach does not allow for the alignment procedure previously described Instead, it is essential to employ a reference angled plug that has been measured using alternative methods.

Figure 2 – Example of set-up of angle measurement by means of interferometer

Phase differences between the reference wavefront and the wavefront from the surface of the ferrule under test create a fringe pattern.

The ferrule is adjusted to a nominal angle θ₀ using a micropositioner For a convex polished ferrule, the curvature radius R and the apex offset component in the direction of the angle Eₓ are determined through the analysis of the interferometric pattern The angle is then calculated based on the measurements of R and Eₓ.

Figure 3 – Example of interference pattern of a convex polished ferrule

For a flat polished tip, the angle is determined by the frequency of the interference fringes in the direction of the angle, which is based on the number of waves per unit length, represented as $1/\Lambda$.

Figure 4 – Exemple de zone d'interférence d'un embout poli plat

In this method, the terminal face of the tip is positioned in an adjustable micropositioner under an interferometric microscope The tip is tilted until the terminal face is perpendicular to the optical axis of the interferometer, indicating the accurate angle has been achieved For a polished convex tip, this alignment occurs when the interference rings and the fiber are symmetrical to the rotation axis Conversely, for a flat polished tip, the correct position is reached when the interference fringes either disappear or reduce to a minimal number.

Franges interférométriques Centre de franges

Figure 5 – Exemple de zone d'interférence d'un embout poli convexe réglé pour la mesure de la méthode 2

L'angle de la face terminale de l'embout peut être lu sur le cadran du micropositionneur.

2.3 Méthode 3 – Méthode du profilomètre mécanique

Dans cette méthode, l'angle de la face terminale est évalué en profilant l'embout de la face terminale avec l'analyseur de surface.

The probe is mounted in a fixed support resembling a mechanical profilometer The probe's axis must be parallel to the stylus axis, and the tip should be positioned at an angle aligned with the stylus's scanning direction.

L'angle de la face terminale de l'embout est évalué à partir de l'analyse du profil acquis. Λ

The angle of a flat polished ferrule is determined by analyzing the frequency of the interferometric fringes in the angle direction, which corresponds to the number of waves per unit length.

Figure 4 – Example of interference pattern of a flat polished ferrule

Method 2 – Manual interferometric method

In this method, the ferrule endface is positioned in a tiltable micropositioner beneath a microscope equipped with interferometric capabilities The ferrule is adjusted until its surface aligns perpendicularly to the optical axis of the interferometer, achieving the correct angle For a convex polished ferrule endface, this alignment is indicated by symmetrical interference rings and fiber around the rotation axis Conversely, for a flat polished ferrule, the optimal position is identified when the interference fringes either vanish or reach their minimum count.

Figure 5 – Example of interference pattern of a convex polished ferrule adjusted for method 2 measurement

The endface angle of the ferrule can be read at the dial of the micropositioner.

Method 3 – Mechanical profilometer method

In this method, the endface angle is evaluated by profiling the endface ferrule with a surface analyser.

The ferrule is securely positioned in a fixed holder beneath the stylus of a mechanical profilometer It is essential that the ferrule axis aligns parallel to the stylus axis, with the plug oriented at an angle that aligns with the direction of the stylus scan.

The endface angle of the ferrule is evaluated from the analysis of the acquired profile. Λ

2.4 Méthode 4 – Méthode de la lumière réfléchie

In this method, a visible He-Ne light beam is aligned along the axis of the tip, reflected by the tip's terminal face, and directed towards a screen where an energy zone is formed The screen is perpendicular to the tip's axis and extends around it.

Rainure en V ou manchon de précision

NOTE – Pour des embouts polis convexes, une longueur appropriée L peut se situer entre 20 cm et 50 cm et peut être enregistrée dans le cadre des résultats d'essai.

Figure 6 – Exemple de montage pour la mesure de l'angle de la face terminale de l'embout

In the case of a flat-polished terminal face, the energy zone typically appears as a small, uniformly illuminated circle, characterized by minimal additional divergence from the laser beam Conversely, for a spherically polished terminal face, the captured image usually manifests as a small ring (Airy disk) at the center of a larger visible circle, which is formed by a beam that has diverged from the original laser beam This small ring results from the Fraunhofer diffraction of the He-Ne beam reflected by the spherical terminal face, which contains a fiber or a fiber hole as the central aperture.

Embout poli plat Embout poli convexe

The terminal face angle of the tip q is determined by measuring the deviation angle of the He-Ne beam at the center of the visible circle or the energy zone ring while rotating the tip around its axis.

The resolution of the reflected beam is influenced by the finish level of the terminal face surface of the tip This surface must be polished to a degree that allows for a well-defined specular reflection of the He-Ne beam.

Cette méthode ne doit s'appliquer qu'aux embouts polis plats.

Method 4 – Reflected light method