EN IEC 61280-1-4:2023

Fibre optic communication subsystem test procedures - Part 1-4: General communication subsystems - Light source encircled flux measurement method

IEC 61280-1-4:2023 is available as IEC 61280-1-4:2023 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition.IEC 61280-1-4:2023 establishes the characterization process of the encircled flux measurement method of light sources intended to be used with multimode fibre. This document sets forth a procedure for the collection of two-dimensional fibre optic nearfield greyscale data and subsequent reduction to one-dimensional data expressed as a set of three sampled parametric functions of radius from the fibre’s optical centre. Estimation of the fibre core diameter is not an objective of this document. This third edition cancels and replaces the second edition published in 2009. This edition constitutes a technical revision. This edition includes the following significant technical changes with respect to the previous edition: - improvement of calibration procedure and calibration traceability; - improvement of fibre shaker description and requirements; - addition of pulsed light sources; - removal of a poorly traceable calibration process using a micro positioner.

Lichtwellenleiter-Kommunikationsuntersysteme - Grundlegende Prüfverfahren - Teil 1-4: Allgemeine Kommunikationsuntersysteme - Verfahren zur Messung des begrenzten Lichtstroms einer Strahlungsquelle

Procédures d’essai des sous-systèmes de télécommunication fibroniques - Partie 1-4: Sous-systèmes généraux de télécommunication - Méthode de mesure du flux inscrit de la source optique

IEC 61280-1-4:2023 est disponible sous forme de IEC 61280-1-4:2023 RLV qui contient la Norme internationale et sa version Redline, illustrant les modifications du contenu technique depuis l'édition précédente.L'IEC 61280-1-4:2023 stipule le processus de caractérisation de la méthode de mesure du flux inscrit de sources optiques destinées à être utilisées avec des fibres multimodales. Le présent document définit une procédure consistant à collecter des données fibroniques de champ proche, bidimensionnelles et en niveaux de gris, puis à les réduire en données unidimensionnelles exprimées sous la forme d’un ensemble de trois fonctions paramétriques échantillonnées du rayon par rapport au centre optique de la fibre. Cette troisième édition annule et remplace la deuxième édition parue en 2009. Cette édition constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l’édition précédente: - amélioration de la procédure et de la traçabilité de l’étalonnage; - amélioration de la description et des exigences relatives à l’agitateur de fibre; - ajout des sources optiques pulsées; - suppression d’un processus d’étalonnage utilisant un micropositionneur, en raison de sa faible traçabilité.

Postopki preskušanja optičnega komunikacijskega podsistema - 1-4. del: Splošni komunikacijski podsistemi - Merilna metoda za pretok, ki ga obkroža svetlobni vir (IEC 61280-1-4:2023)

General Information

• Status: Published
• Publication Date: 23-Feb-2023
• ICS: 33.180.01 - Fibre optic systems in general
• Technical Committee: CLC/SR 86C - Fibre optic systems and active devices
• Drafting Committee: IEC/SC 86C - IEC_SC_86C
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 24-Feb-2023
• Due Date: 27-Oct-2023
• Completion Date: 24-Feb-2023
• Ref Project: SIST EN IEC 61280-1-4:2023 - Fibre optic communication subsystem test procedures - Part 1-4: General communication subsystems - Light source encircled flux measurement method (IEC 61280-1-4:2023)

Relations

• Replaces: EN 61280-1-4:2010 - Fibre optic communication subsystem test procedures - Part 1-4: General communication subsystems - Light source encircled flux measurement method
• Effective Date: 23-Jan-2023

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN IEC 61280-1-4:2023
01-april-2023
Nadomešča:
SIST EN 61280-1-4:2010
Postopki preskušanja optičnega komunikacijskega podsistema - 1-4. del: Splošni

komunikacijski podsistemi - Merilna metoda za pretok, ki ga obkroža svetlobni vir

(IEC 61280-1-4:2023)
Fibre optic communication subsystem test procedures - Part 1-4: General
communication subsystems - Light source encircled flux measurement method (IEC
61280-1-4:2023)

Lichtwellenleiter-Kommunikationsuntersysteme - Grundlegende Prüfverfahren - Teil 1-4:

Allgemeine Kommunikationsuntersysteme - Verfahren zur Messung des begrenzten
Lichtstroms einer Strahlungsquelle (IEC 61280-1-4:2023)

Procédures d’essai des sous-systèmes de télécommunications fibroniques - Partie 1-4:

Sous-systèmes généraux de télécommunication - Méthode de mesure du flux inscrit de

la source optique (IEC 61280-1-4:2023)
Ta slovenski standard je istoveten z: EN IEC 61280-1-4:2023
ICS:
33.180.01 Sistemi z optičnimi vlakni na Fibre optic systems in
splošno general
SIST EN IEC 61280-1-4:2023 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN IEC 61280-1-4:2023
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SIST EN IEC 61280-1-4:2023
EUROPEAN STANDARD EN IEC 61280-1-4
NORME EUROPÉENNE
EUROPÄISCHE NORM February 2023
ICS 33.180.01 Supersedes EN 61280-1-4:2010
English Version
Fibre optic communication subsystem test procedures - Part 1-4:
General communication subsystems - Light source encircled flux
measurement method
(IEC 61280-1-4:2023)

Procédures d'essai des sous-systèmes de Lichtwellenleiter-Kommunikationsuntersysteme -

télécommunication fibroniques - Partie 1-4: Sous-systèmes Grundlegende Prüfverfahren - Teil 1-4: Allgemeine

généraux de télécommunication - Méthode de mesure du Kommunikationsuntersysteme - Verfahren zur Messung des

flux inscrit de la source optique begrenzten Lichtstroms einer Strahlungsquelle
(IEC 61280-1-4:2023) (IEC 61280-1-4:2023)

This European Standard was approved by CENELEC on 2023-02-23. CENELEC members are bound to comply with the CEN/CENELEC

Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration.

Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the CEN-CENELEC

Management Centre or to any CENELEC member.

This European Standard exists in three official versions (English, French, German). A version in any other language made by translation

under the responsibility of a CENELEC member into its own language and notified to the CEN-CENELEC Management Centre has the

same status as the official versions.

CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic,

Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the

Netherlands, Norway, Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,

Türkiye and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels

© 2023 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. EN IEC 61280-1-4:2023 E
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SIST EN IEC 61280-1-4:2023
EN IEC 61280-1-4:2023 (E)
European foreword

The text of document 86C/1806/CDV, future edition 3 of IEC 61280-1-4, prepared by SC 86C "Fibre

optic systems and active devices" of IEC/TC 86 "Fibre optics" was submitted to the IEC-CENELEC

parallel vote and approved by CENELEC as EN IEC 61280-1-4:2023.
The following dates are fixed:

• latest date by which the document has to be implemented at national (dop) 2023-08-23

level by publication of an identical national standard or by endorsement

• latest date by which the national standards conflicting with the (dow) 2026-02-23

document have to be withdrawn

This document supersedes EN 61280-1-4:2010 and all of its amendments and corrigenda (if any).

Attention is drawn to the possibility that some of the elements of this document may be the subject of

patent rights. CENELEC shall not be held responsible for identifying any or all such patent rights.

Any feedback and questions on this document should be directed to the users’ national committee. A

complete listing of these bodies can be found on the CENELEC website.
Endorsement notice

The text of the International Standard IEC 61280-1-4:2023 was approved by CENELEC as a

European Standard without any modification.

In the official version, for Bibliography, the following notes have to be added for the standard indicated:

IEC 60793-1-20 NOTE Approved as EN 60793-1-20
IEC 60793-1-41 NOTE Approved as EN 60793-1-41
IEC 61745:2017 NOTE Approved as EN 61745:2017 (not modified)
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SIST EN IEC 61280-1-4:2023
EN IEC 61280-1-4:2023 (E)
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies. For

undated references, the latest edition of the referenced document (including any amendments)

applies.

NOTE 1 Where an International Publication has been modified by common modifications, indicated by (mod), the

relevant EN/HD applies.

NOTE 2 Up-to-date information on the latest versions of the European Standards listed in this annex is available

here: www.cenelec.eu.
Publication Year Title EN/HD Year
IEC 60793-2-10 - Optical fibres - Part 2-10: Product EN IEC 60793-2-10 -
specifications - Sectional specification for
category A1 multimode fibres
IEC 60825-1 - Safety of laser products - Part 1: EN 60825-1 -
Equipment classification and requirements
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SIST EN IEC 61280-1-4:2023
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SIST EN IEC 61280-1-4:2023
IEC 61280-1-4
Edition 3.0 2023-01
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside
Fibre optic communication subsystem test procedures –
Part 1-4: General communication subsystems – Light source encircled flux
measurement method
Procédures d’essai des sous-systèmes de télécommunication fibroniques –
Partie 1-4: Sous-systèmes généraux de télécommunication – Méthode de
mesure du flux inscrit de la source optique
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.180.01 ISBN 978-2-8322-6361-7

Warning! Make sure that you obtained this publication from an authorized distributor.

Attention! Veuillez vous assurer que vous avez obtenu cette publication via un distributeur agréé.

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale
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SIST EN IEC 61280-1-4:2023
– 2 – IEC 61280-1-4:2023 © IEC 2023
CONTENTS

FOREWORD ........................................................................................................................... 4

INTRODUCTION ..................................................................................................................... 6

1 Scope .............................................................................................................................. 7

2 Normative references ...................................................................................................... 7

3 Terms and definitions ...................................................................................................... 7

4 Symbols .......................................................................................................................... 8

5 Assumptions .................................................................................................................. 10

5.1 Assumptions applicable to the characterization of data sources ............................ 10

5.2 Assumptions applicable to the characterization of measurement sources .............. 10

6 Apparatus ...................................................................................................................... 10

6.1 Common apparatus ............................................................................................... 10

6.1.1 General ......................................................................................................... 10

6.1.2 Computer....................................................................................................... 10

6.1.3 Image digitizer ............................................................................................... 11

6.1.4 Detector ........................................................................................................ 11

6.1.5 Magnifying optics ........................................................................................... 11

6.1.6 Attenuator ...................................................................................................... 12

6.1.7 Micro positioner (optional) ............................................................................. 12

6.1.8 Input port ....................................................................................................... 12

6.1.9 Calibration light source .................................................................................. 12

6.2 Transmission source apparatus ............................................................................ 13

6.2.1 General ......................................................................................................... 13

6.2.2 Test jumper assembly .................................................................................... 13

6.2.3 Fibre shaker .................................................................................................. 13

6.3 Measurement source apparatus ............................................................................ 15

7 Sampling and specimens ............................................................................................... 15

8 Geometric calibration ..................................................................................................... 15

9 Measurement procedure ................................................................................................ 15

9.1 Safety ................................................................................................................... 15

9.2 Image acquisition .................................................................................................. 15

9.2.1 Raw image acquisition ................................................................................... 15

9.2.2 Dark image acquisition .................................................................................. 16

9.2.3 Corrected image ............................................................................................ 16

9.3 Optical centre determination ................................................................................. 16

9.3.1 General ......................................................................................................... 16

9.3.2 Centroid image .............................................................................................. 17

9.3.3 Centroid computation ..................................................................................... 17

9.4 Test source image acquisition ............................................................................... 18

10 Computation of encircled flux ........................................................................................ 18

10.1 Computation of radial data functions ..................................................................... 18

10.2 Integration limit and baseline determination .......................................................... 20

10.2.1 Integration limit .............................................................................................. 20

10.2.2 Baseline determination .................................................................................. 20

10.2.3 Baseline subtraction ...................................................................................... 20

10.3 Computation of encircled flux ................................................................................ 21

11 Results .......................................................................................................................... 21

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SIST EN IEC 61280-1-4:2023
IEC 61280-1-4:2023 © IEC 2023 – 3 –

11.1 Information available with each measurement ....................................................... 21

11.2 Information available upon request ....................................................................... 21

12 Specification information ............................................................................................... 22

Annex A (informative) Measurement sensitivity considerations ............................................ 23

A.1 Baseline averaging considerations ........................................................................ 23

A.2 Pixel sensitivity variation calibration ...................................................................... 25

A.3 Correlated double sampling .................................................................................. 25

A.4 Imperfections of practical detectors and optics ...................................................... 26

Bibliography .......................................................................................................................... 28

Figure 1 – Apparatus block diagram ...................................................................................... 10

Figure 2 – Typical set-up for transmission source measurement ........................................... 13

Figure 3 – Fibre shaker example ........................................................................................... 14

Figure 4 – Pixel and ring illustration ...................................................................................... 18

Figure A.1 – Core images from instrument A and instrument B ............................................. 23

Figure A.2 – Compressed core images from instrument A and instrument B .......................... 24

Figure A.3 – Intensity versus radius for instruments A and B................................................. 24

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SIST EN IEC 61280-1-4:2023
– 4 – IEC 61280-1-4:2023 © IEC 2023
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
FIBRE OPTIC COMMUNICATION SUBSYSTEM
TEST PROCEDURES –
Part 1-4: General communication subsystems –
Light source encircled flux measurement method
FOREWORD

1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

all national electrotechnical committees (IEC National Committees). The object of IEC is to promote international

co-operation on all questions concerning standardization in the electrical and electronic fields. To this end and

in addition to other activities, IEC publishes International Standards, Technical Specifications, Technical Reports,

Publicly Available Specifications (PAS) and Guides (hereafter referred to as "IEC Publication(s)"). Their

preparation is entrusted to technical committees; any IEC National Committee interested in the subject dealt with

may participate in this preparatory work. International, governmental and non-governmental organizations liaising

with the IEC also participate in this preparation. IEC collaborates closely with the International Organization for

Standardization (ISO) in accordance with conditions determined by agreement between the two organizations.

2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

consensus of opinion on the relevant subjects since each technical committee has representation from all

interested IEC National Committees.

3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

misinterpretation by any end user.

4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

transparently to the maximum extent possible in their national and regional publications. Any divergence between

any IEC Publication and the corresponding national or regional publication shall be clearly indicated in the latter.

5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity

assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any

services carried out by independent certification bodies.

6) All users should ensure that they have the latest edition of this publication.

7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

members of its technical committees and IEC National Committees for any personal injury, property damage or

other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

Publications.

8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

indispensable for the correct application of this publication.

9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of patent

rights. IEC shall not be held responsible for identifying any or all such patent rights.

IEC 61280‑1‑4 has been prepared by subcommittee 86C: Fibre optic systems and active

devices, of IEC technical committee 86: Fibre optics. It is an International Standard.

This third edition cancels and replaces the second edition published in 2009. This edition

constitutes a technical revision.

This edition includes the following significant technical changes with respect to the previous

edition:
a) improvement of calibration procedure and calibration traceability;
b) improvement of fibre shaker description and requirements;
c) addition of pulsed light sources;
d) removal of a poorly traceable calibration process using a micro positioner.
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SIST EN IEC 61280-1-4:2023
IEC 61280-1-4:2023 © IEC 2023 – 5 –
The text of this International Standard is based on the following documents:
Draft Report on voting
86C/1806/CDV 86C/1828/RVC

Full information on the voting for its approval can be found in the report on voting indicated in

the above table.
The language used for the development of this International Standard is English.

This document was drafted in accordance with ISO/IEC Directives, Part 2, and developed in

accordance with ISO/IEC Directives, Part 1 and ISO/IEC Directives, IEC Supplement, available

at www.iec.ch/members_experts/refdocs. The main document types developed by IEC are

described in greater detail at www.iec.ch/publications.

A list of all parts of the IEC 61280 series can be found, under the general title Fibre optic

communication subsystem test procedures, on the IEC website.

The committee has decided that the contents of this document will remain unchanged until the

stability date indicated on the IEC website under webstore.iec.ch in the data related to the

specific document. At this date, the document will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

IMPORTANT – The "colour inside" logo on the cover page of this document indicates that it

contains colours which are considered to be useful for the correct understanding of its

contents. Users should therefore print this document using a colour printer.
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SIST EN IEC 61280-1-4:2023
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INTRODUCTION

This part of IEC 61280 specifies how to measure the encircled flux of a multimode light source.

Encircled flux is a fraction of the cumulative output power to the total output power as a function

of radial distance from the centre of the multimode optical fibre’s core.

The basic approach is to collect two-dimensional (2D) nearfield data, using a calibrated camera,

and to mathematically convert the 2D data into three normalized functions of radial distance

from the fibre’s optical centre. The three functions are intensity, incremental flux, and encircled

flux. The intensity represents optical power per surface area (in watts per square meter). The

incremental flux represents optical power per radius differential (in watts per meter), and the

encircled flux represents a fraction of the cumulative output power to the total output power.

These three radial functions are intended to characterize fibre optic laser sources either for use

in mathematical models predicting the minimum guaranteed length of a communications link, or

to qualify a light source to measure insertion loss in multimode links.
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SIST EN IEC 61280-1-4:2023
IEC 61280-1-4:2023 © IEC 2023 – 7 –
FIBRE OPTIC COMMUNICATION SUBSYSTEM
TEST PROCEDURES –
Part 1-4: General communication subsystems –
Light source encircled flux measurement method
1 Scope

This part of IEC 61280 establishes the characterization process of the encircled flux

measurement method of light sources intended to be used with multimode fibre.

This document sets forth a procedure for the collection of two-dimensional fibre optic nearfield

greyscale data and subsequent reduction to one-dimensional data expressed as a set of three

sampled parametric functions of radius from the fibre’s optical centre.
Estimation of the fibre core diameter is not an objective of this document.
2 Normative references

The following documents are referred to in the text in such a way that some or all of their content

constitutes requirements of this document. For dated references, only the edition cited applies.

For undated references, the latest edition of the referenced document (including any

amendments) applies.

IEC 60793-2-10, Optical fibres – Part 2-10: Product specifications – Sectional specification for

category A1 multimode fibres

IEC 60825-1, Safety of laser products – Part 1: Equipment classification and requirements

3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

ISO and IEC maintain terminology databases for use in standardization at the following

addresses:
• IEC Electropedia: available at https://www.electropedia.org/
• ISO Online browsing platform: available at https://www.iso.org/obp
3.1
calibration light source
light source used to find the optical centre of a multimode fibre
3.2
centroid image
image used to determine the optical centre of the multimode fibre core
3.3
corrected image

image which has had a dark image subtracted from it and whose elements have had uniformity

correction applied
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SIST EN IEC 61280-1-4:2023
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3.4
dark image

image taken with the measured light source either turned off or not installed in the input port

Note 1 to entry: Stray light and electrical signals of the detection system will remain in the dark image.

3.5
image

two-dimensional rectangular array of numbers whose elements are pixels and whose pixel

values linearly correspond to the optical power falling on the pixels
3.6
light source

something that emits light that is coupled into a fibre, the output of which can be measured

EXAMPLE Calibration light source, transmission light source, light source used for attenuation measurements.

3.7
measurement light source
light source intended to be used in the measurement of attenuation
3.8
nominal core radius
half the nominal core diameter of the multimode fibre to be measured
3.9
ring smoothing

technique to reduce the two dimensional near field image into a 1-D near field intensity profile

while cancelling the effects of the periodic spacing of imager pixels of finite area

3.10
transmission light source
light source used to transmit digital data over multimode fibre optic links
3.11
uniformity correction

process to correct the sensitivity of a pixel so that it performs substantially like an average pixel

3.12
valid pixel

optical detection element in the detector matrix whose sensitivity, when corrected, is within 5 %

of the mean sensitivity of the average conversion efficiency of the detector
4 Symbols
B baseline intensity

NOTE 1 This value is determined from a region of the computed near field just outside the

core boundary.
D distance from the centre of the centroid image to the nearest boundary of
the image

D , D , D , D set of distances from the centre of the centroid image to, respectively, the

L R T B
left, right, top and bottom boundaries of the image
NOTE 2 The minimum of this set is used to compute D.
EF(i) encircled flux vector
EF'(i) non-normalized encircled flux vector
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SIST EN IEC 61280-1-4:2023
IEC 61280-1-4:2023 © IEC 2023 – 9 –
i index parameter used in the parametric result vectors and EF(i)
I matrix of pixel intensities of a dark image as measured by the detector and
dark
digitizer
matrix of pixel intensities of the light source, before correction, as measured
raw
by the detector and image digitizer
I near-field intensity matrix
r,c

NOTE 3 This is a matrix of pixel intensities, based on I , as measured by the detector and

raw
corrected using U and I .
dark
smoothed intensity vector, each element being the arithmetic average
I(i) ring-
of the set of radial coordinates of all the pixels in a given ring
N number of rings used to compute the 1-D near field
N number of rows in an image
NOTE 4 All columns in an image have the same number of rows.
N number of columns in an image
NOTE 5 All rows in an image have the same number of columns.
P most intense valid pixel in the centroid image
Max
P least intense valid pixel in the centroid image
Min

R radial coordinate, in μm, of the centre of any pixel, referenced to the optical

centre X , Y
0 0
R(i) ring-smoothed radial vector, each element being the arithmetic average of
the radii of all the pixels in the i ring
R integration limit along the radius
max
S column-weighted summation of all pixel intensities greater than T in the
centroid image
S (i) intensity summation vector used in ring smoothing
S summation of all pixel intensities greater than T in the centroid image
S (i) pixel counting vector used in ring smoothing
S (i) radius summation vector used in ring smoothing
S row-weighted summation of all pixel intensities greater than T in the centroid
image
S horizontal geometric calibration factor (along columns)
S vertical geometric calibration factor (along rows)
T threshold used to determine which pixels in the centroid image will be used
to determine the optical centre
NOTE 6 All pixels greater than or equal to T are used to compute the centroid.
U sensitivity correction matrix, applied to a dark-subtracted image to reduce
r,c
non-uniformity of the detector’s pixel-to-pixel conversion efficiency
W half-width, in μm, of the rings used to compute the 1-D near field
X X axis (column) location of the centre of the centroid image
Y Y axis (row) location of the centre of the centroid image
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5 Assumptions
5.1 Assumptions applicable to the characterization of data sources

The 50 μm or 62,5 μm core near-parabolic graded-index multimode fibre used as the "test

jumper assembly" is treated as if it possessed perfect circular symmetry about its optical centre,

because asymmetries in the launched optical flux distributions will dominate any distortions

introduced by the test jumper assembly, such as lateral and angular misalignments. It is further

assumed that all cladding modes will be stripped by passage through the specified ten metres

or more of fibre. The modes of a mode group need not carry equal flux. In fact, with such short

fibres, one thousand metres or less, unequal distribution of flux in the modes of a group is the

norm, not the exception.
5.2 Assumptions applicable to the characterization of measurement sources

Measurement sources are assumed to be sufficiently broadband and incoherent, so that speckle

is not a problem, and to have a sufficiently symmetrica
...

SLOVENSKI STANDARD
oSIST prEN IEC 61280-1-4:2022
01-oktober-2022
Postopki preskušanja optičnega komunikacijskega podsistema - 1-4. del: Splošni

komunikacijski podsistemi - Merilna metoda za pretok, ki ga obkroža svetlobni vir

Fibre optic communication subsystem test procedures - Part 1-4: General
communication subsystems - Light source encircled flux measurement method

Lichtwellenleiter-Kommunikationsuntersysteme - Grundlegende Prüfverfahren - Teil 1-4:

Allgemeine Kommunikationsuntersysteme - Verfahren zur Messung des begrenzten
Lichtstroms einer Strahlungsquelle

Procédures d’essai des sous-systèmes de télécommunications fibroniques - Partie 1-4:

Sous-systèmes généraux de télécommunication - Méthode de mesure du flux inscrit de

la source optique
Ta slovenski standard je istoveten z: prEN IEC 61280-1-4:2022
ICS:
33.180.01 Sistemi z optičnimi vlakni na Fibre optic systems in
splošno general
oSIST prEN IEC 61280-1-4:2022 en

2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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oSIST prEN IEC 61280-1-4:2022
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oSIST prEN IEC 61280-1-4:2022
86C/1806/CDV
COMMITTEE DRAFT FOR VOTE (CDV)
PROJECT NUMBER:
IEC 61280-1-4 ED3
DATE OF CIRCULATION: CLOSING DATE FOR VOTING:
2022-07-22 2022-10-14
SUPERSEDES DOCUMENTS:
86C/1777/CD, 86C/1805/CC
IEC SC 86C : FIBRE OPTIC SYSTEMS AND ACTIVE DEVICES
SECRETARIAT: SECRETARY:
United States of America Mr Fred Heismann
OF INTEREST TO THE FOLLOWING COMMITTEES: PROPOSED HORIZONTAL STANDARD:
Other TC/SCs are requested to indicate their interest, if
any, in this CDV to the secretary.
FUNCTIONS CONCERNED:
EMC ENVIRONMENT QUALITY ASSURANCE SAFETY

SUBMITTED FOR CENELEC PARALLEL VOTING NOT SUBMITTED FOR CENELEC PARALLEL VOTING

Attention IEC-CENELEC parallel voting
The attention of IEC National Committees, members of
CENELEC, is drawn to the fact that this Committee Draft
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The CENELEC members are invited to vote through the
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This document is still under study and subject to change. It should not be used for reference purposes.

Recipients of this document are invited to submit, with their comments, notification of any relevant patent rights of

which they are aware and to provide supporting documentation.
TITLE:

Fibre optic communication subsystem test procedures - Part 1-4: General communication

subsystems - Light source encircled flux measurement method
PROPOSED STABILITY DATE: 2026
NOTE FROM TC/SC OFFICERS:

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document was extracted from the on-line authoring tool, but its format is not completely compliant with

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1 CONTENTS

3 FOREWORD ........................................................................................................................... 4

4 INTRODUCTION ..................................................................................................................... 6

5 1 Scope .............................................................................................................................. 7

6 2 Normative references ........................................................................................................ 7

7 3 Terms and definitions ........................................................................................................ 7

8 4 Symbols .......................................................................................................................... 8

9 5 Assumptions .................................................................................................................. 10

10 5.1 Assumptions applicable to the characterization of data sources .............................. 10

11 5.2 Assumptions applicable to the characterization of measurement sources. ............... 10

12 6 Apparatus ...................................................................................................................... 10

13 6.1 Common apparatus ................................................................................................ 10

14 6.1.1 General ......................................................................................................... 10

15 6.1.2 Computer ....................................................................................................... 11

16 6.1.3 Image digitizer ............................................................................................... 11

17 6.1.4 Detector ......................................................................................................... 11

18 6.1.5 Magnifying optics ........................................................................................... 12

19 6.1.6 Attenuator ...................................................................................................... 12

20 6.1.7 Micro positioner (optional) ............................................................................. 12

21 6.1.8 Input port ....................................................................................................... 13

22 6.1.9 Calibration light source .................................................................................. 13

23 6.2 Transmission source apparatus ............................................................................. 13

24 6.2.1 General ......................................................................................................... 13

25 6.2.2 Test jumper assembly .................................................................................... 14

26 6.2.3 Fibre shaker .................................................................................................. 14

27 6.3 Measurement source apparatus ............................................................................. 15

28 7 Sampling and specimens ................................................................................................ 15

29 8 Geometric calibration ...................................................................................................... 16

30 9 Measurement procedure ................................................................................................ 16

31 9.1 Safety ................................................................................................................... 16

32 9.2 Image acquisition ................................................................................................... 16

33 9.2.1 Raw image acquisition ................................................................................... 16

34 9.2.2 Dark image acquisition .................................................................................. 16

35 9.2.3 Corrected image ............................................................................................ 17

36 9.3 Optical centre determination .................................................................................. 17

37 9.3.1 General ......................................................................................................... 17

38 9.3.2 Centroid image .............................................................................................. 17

39 9.3.3 Centroid computation ..................................................................................... 17

40 9.4 Test source image acquisition ................................................................................ 18

41 10 Computation of encircled flux ......................................................................................... 18

42 10.1 Computation of radial data functions ...................................................................... 18

43 10.2 Integration limit and baseline determination ........................................................... 20

44 10.2.1 Integration limit .............................................................................................. 20

45 10.2.2 Baseline determination .................................................................................. 21

46 10.2.3 Baseline subtraction ...................................................................................... 21

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47 10.3 Computation of encircled flux ................................................................................. 21

48 11 Results .......................................................................................................................... 21

49 11.1 Information available with each measurement ........................................................ 21

50 11.2 Information available upon request ........................................................................ 22

51 12 Specification information ................................................................................................ 22

52 Annex A (informative) Measurement sensitivity considerations ............................................. 23

53 A.1 Baseline averaging considerations ........................................................................ 23

54 A.2 Pixel sensitivity variation calibration ....................................................................... 25

55 A.3 Correlated double sampling ................................................................................... 26

56 A.4 Imperfections of practical detectors and optics ....................................................... 26

57 Bibliography .......................................................................................................................... 29

59 Figure 1 – Apparatus block diagram ...................................................................................... 11

60 Figure 2 – Typical set-up for transmission source measurement ........................................... 14

61 Figure 3 – Fibre shaker example ........................................................................................... 15

62 Figure 4 – Pixel and ring illustration ...................................................................................... 19

63 Figure A.1 – Core images from instrument A and instrument B ............................................... 23

64 Figure A.2 – Compressed core images from instrument A and instrument B ........................... 24

65 Figure A.3 – Intensity versus radius for Instruments A and B .................................................. 25

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68 INTERNATIONAL ELECTROTECHNICAL COMMISSION
69 ____________
71 FIBRE OPTIC COMMUNICATION SUBSYSTEM TEST PROCEDURES –
74 Part 1-4: General communication subsystems – Light source encircled flux
76 FOREWORD

77 1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising

78 all national electrotechnical committees (IEC National Committees). The object of IEC is to promote

79 international co-operation on all questions concerning standardization in the electrical and electronic fields. To

80 this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,

81 Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC

82 Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested

83 in the subject dealt with may participate in this preparatory work. International, governmental and non-

84 governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely

85 with the International Organization for Standardization (ISO) in accordance with conditions determined by

86 agreement between the two organizations.

87 2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international

88 consensus of opinion on the relevant subjects since each technical committee has representation from all

89 interested IEC National Committees.

90 3) IEC Publications have the form of recommendations for international use and are accepted by IEC National

91 Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC

92 Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any

93 misinterpretation by any end user.

94 4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications

95 transparently to the maximum extent possible in their national and regional publications. Any divergence

96 between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in

97 the latter.

98 5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity

99 assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any

100 services carried out by independent certification bodies.

101 6) All users should ensure that they have the latest edition of this publication.

102 7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and

103 members of its technical committees and IEC National Committees for any personal injury, property damage or

104 other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and

105 expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC

106 Publications.

107 8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is

108 indispensable for the correct application of this publication.

109 9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

110 patent rights. IEC shall not be held responsible for identifying any or all such patent rights.

111 IEC 61280‑1‑4 has been prepared by subcommittee 86C: Fibre optic systems and active

112 devices, of IEC technical committee 86: Fibre optics. It is an International Standard.

113 This third edition cancels and replaces the second edition published in 2009. This edition

114 constitutes a technical revision.

115 This edition includes the following significant technical changes with respect to the previous

116 edition:
117 a) improvement of calibration procedure and calibration traceability;
118 b) improvement of fibre shaker description and requirements;
119 c) addition of pulsed light sources;

120 d) removal of a poorly traceable calibration process using a micro positioner.

121 The text of this standard is based on the following documents:
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Draft Report on voting
86C/XX/FDIS 86C/XX/RVD
122

123 Full information on the voting for the approval of this standard can be found in the report on

124 voting indicated in the above table.

125 The language used for the development of this International Standard is English.

126 This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

127 A list of all parts of the IEC 61280 series can be found, under the general title Fibre optic

128 communication subsystem test procedures, on the IEC website.

129 The committee has decided that the contents of this publication will remain unchanged until the

130 maintenance result date indicated on the IEC web site under "http://webstore.iec.ch" in the

131 data related to the specific publication. At this date, the publication will be

132 • reconfirmed,
133 • withdrawn,
134 • replaced by a revised edition, or
135 • amended.
136

The “colour inside” logo on the cover page of this publication indicates that it contains

colours which are considered to be useful for the correct understanding of its contents.

Users should therefore print this publication using a colour printer.
137
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138
139 INTRODUCTION

140 This part of IEC 61280 specifies how to measure the encircled flux of a multimode light source. Encircled

141 flux is a fraction of the cumulative output power to the total output power as a function of radial

142 distance from the centre of the multimode optical fibre’s core.

143 The basic approach is to collect two-dimensional (2D) nearfield data, using a calibrated camera, and to

144 mathematically convert the 2D data into three normalized functions of radial distance from the fibre’s

145 optical centre. The three functions are intensity, incremental flux, and encircled flux. The intensity

146 represents optical power per surface area (in watts per square meter). The incremental flux represents

147 optical power per radius differential (in watts per meter), and the encircled flux represents a fraction of

148 the cumulative output power to the total output power.

149 These three radial functions are intended to characterize fibre optic laser sources either for use in

150 mathematical models predicting the minimum guaranteed length of a communications link, or to qualify

151 a light source to measure insertion loss in multimode links.
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152 FIBRE OPTIC COMMUNICATION SUBSYSTEM TEST PROCEDURES –
153
154 Part 1-4: General communication subsystems - Light source encircled flux
155 measurement method
156
157 1 Scope

158 This part of IEC 61280 establishes the characterization process of the encircled flux

159 measurement method of light sources intended to be used with multimode fibre.

160 This international standard sets forth a procedure for the collection of two-dimensional fibre

161 optic nearfield greyscale data and subsequent reduction to one-dimensional data expressed

162 as a set of three sampled parametric functions of radius from the fibre’s optical centre.

163 Estimation of the fibre core diameter is not an objective of this standard.
164 2 Normative references

165 The following referenced documents are indispensable for the application of this document. For

166 dated references, only the edition cited applies. For undated references, the latest edition of

167 the referenced document (including any amendments) applies.

168 IEC 61745:2017, End-face image analysis procedure for the calibration of optical fibre

169 geometry test sets

170 IEC 60793‑2‑10, Optical fibres – Part 2-10: Product specifications – Sectional specification for

171 category A1 multimode fibres

172 IEC 60825‑1, Safety of laser products – Part 1: Equipment classification and requirements

173 3 Terms and definitions

174 For the purposes of this document, the following terms and definitions apply.

175 ISO and IEC maintain terminological databases for use in standardization at the following

176 addresses:
177 • IEC Electropedia: available at http://www.electropedia.org/
178 • ISO Online browsing platform: available at http://www.iso.org/obp
179 3.1
180 calibration light source
181 light source used to find the optical centre of a multimode fibre
182 3.2
183 centroid image
184 image used to determine the optical centre of the multimode fibre core
185 3.3
186 corrected image

187 image which has had a dark image subtracted from it and whose elements have had uniformity

188 correction applied
189 3.4
190 dark image

191 image taken with the measured light source either turned off or not installed in the input port.

192 Stray light and electrical signals of the detection system will remain in the dark image

193 3.5
194 image

195 two-dimensional rectangular array of numbers whose elements are pixels and whose pixel

196 values linearly correspond to the optical power falling on the pixels
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197 3.6
198 light source

199 something that emits light that is coupled into a fibre, the output of which can be measured

200 (can be a calibration light source, a transmission light source or a light source used for

201 attenuation measurements)
202 3.7
203 measurement light source
204 light source intended to be used in the measurement of attenuation
205 3.8
206 nominal core radius
207 half the nominal core diameter of the multimode fibre to be measured
208 3.9
209 ring smoothing

210 technique to reduce the two dimensional near field image into a 1-D near field intensity profile

211 while cancelling the effects of the periodic spacing of imager pixels of finite area

212 3.10
213 transmission light source
214 light source used to transmit digital data over multimode fibre optic links
215 3.11
216 uniformity correction

217 process to correct the sensitivity of a pixel so that it performs substantially like an average pixel

218 3.12
219 valid pixel

220 optical detection element in the detector matrix whose sensitivity, when corrected, is within 5 %

221 of the mean sensitivity of the average conversion efficiency of the detector
222 4 Symbols

B baseline intensity. This value is determined from a region of the computed near

field just outside the core boundary.
distance from the centre of the centroid image to the nearest boundary of the
image.

set of distances from the centre of the centroid image to, respectively, the left,

D ,D , D , D
L R T B
right, top and bottom boundaries of the image. The minimum of this set is used
to compute D.
EF(i) encircled flux vector.
EF'(i) non-normalized encircled flux vector.
i index parameter used in the parametric result vectors and EF(i).
I matrix of pixel intensities of a dark image as measured by the detector and
dark
digitizer.

I matrix of pixel intensities of the light source, before correction, as measured by

raw
the detector and image digitizer.

I near-field intensity matrix. This is a matrix of pixel intensities, based on I ,

r,c raw
as measured by the detector and corrected using U and I .
dark
ring-smoothed intensity vector, each element being the arithmetic average of
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I(i) the set of radial coordinates of all the pixels in a given ring.
NR number of rings used to compute the 1-D near field.
N number of rows in an image. All columns in an image have the same number of
rows.
N number of columns in an image. All rows in an image have the same number of
columns.
most intense valid pixel in the centroid image.
Max
P least intense valid pixel in the centroid image.
Min

R radial coordinate, in μm, of the centre of any pixel, referenced to the optical

centre X , Y .
0 0
ring-smoothed radial vector, each element being the arithmetic average of the
R(i)
radii of all the pixels in the i ring.
integration limit along the radius
max
column-weighted summation of all pixel intensities greater than T in the
centroid image.
S (i) intensity summation vector used in ring smoothing.
S summation of all pixel intensities greater than T in the centroid image.
S (i) pixel counting vector used in ring smoothing.
S (i) radius summation vector used in ring smoothing.
S row-weighted summation of all pixel intensities greater than T in the centroid
image.
horizontal geometric calibration factor (along columns)
vertical geometric calibration factor (along rows),
T threshold used to determine which pixels in the centroid image will be used to
determine the optical centre. All pixels greater than or equal to T are used to
compute the centroid.

sensitivity correction matrix, applied to a dark-subtracted image to reduce non-

r,c
uniformity of the detector’s pixel-to-pixel conversion efficiency.
W half-width, in μm, of the rings used to compute the 1-D near field.
X x-axis (column) location of the centre of the centroid image.
Y y-axis (row) location of the centre of the centroid image.
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223 5 Assumptions
224 5.1 Assumptions applicable to the characterization of data sources

225 The 50 μm or 62,5 μm core near-parabolic graded-index multimode fibre used as the “test

226 jumper assembly” is treated as if it possessed perfect circular symmetry about its optical centre,

227 because asymmetries in the launched optical flux distributions will dominate any distortions

228 introduced by the test jumper assembly, such as lateral and angular misalignments. It is further

229 assumed that all cladding modes will be stripped by passage through the specified ten metres

230 or more of fibre. The modes of a mode group need not carry equal flux. In fact, with such short

231 fibres, one thousand metres or less, unequal distribution of flux in the modes of a group is the

232 norm, not the exception.
233 5.2 Assumptions applicable to the characterization of measurement sources.

234 Measurement sources are assumed to be sufficiently broadband and incoherent, so that

235 speckle is not a problem, and to have a sufficiently symmetrical nearfield distribution, so that

236 the truncated centroid of that nearfield indicates the location of the optical centre of the fibre

237 with sufficient accuracy for the purposes of this standard.
238 6 Apparatus
239 6.1 Common apparatus
240 6.1.1 General
241 Figure 1 below shows an apparatus block diagram.
242
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243
244

245 The image digitizer can be either part of a camera or a computer add-in board.

246 The detector electronics are usually integral to the camera and digitizer.

247 Attenuation is best placed in the collimating region of the optical path, but not all optical designs will have an

248 accessible collimating region. When this is not possible, the attenuation should be placed on the detector side of the

249 optics.

250 When a micro positioner (not shown) is employed, the input port will be physically attached to it.

251 Figure 1 – Apparatus block diagram
252 6.1.2 Computer

253 A computer is required, because the acquired image contains many thousands of pixels, and

254 the reduction of the image to encircled flux requires substantial computation. The computer will

255 usually be connected to the image digitizer to control the acquisition of an image through

256 software and can also control the micro positioner (and the source, if correlated double

257 sampling is implemented).
258 6.1.3 Image digitizer

259 The nearfield of the fibre core is imaged onto the detector and then digitized by the image

260 digitizer. The image digitizer can be an integral part of a camera, which also contains the

261 detector, or can be an add-in frame-grabber board in the computer.

262 Automatic circuitry in the digitizer, for example AGC or automatic gain control often found in

263 video cameras, shall be disabled.
264 6.1.4 Detector

265 The detector is typically a CCD or CMOS camera. Other types of array cameras can be

266 considered. In any case, detectors shall be both nominally linear and memoryless. Absolute

267 radiometric measurement of flux (optical power flow) is not required.

268 Automatic circuitry in the detector, for example automatic gain control (AGC) often found in

269 video cameras, shall be disabled.

270 The difference in conversion sensitivity from pixel to pixel in the detector will affect the

271 measurement accuracy. The non-uniformity in the corrected conversion efficiency of the

272 detector shall not exceed ± 5 %. It is possible to calibrate and correct a detector, whose

273 uncorrected uniformity is worse than 5 %, by applying a pixel-by-pixel sensitivity correction

274 matrix, U, to the raw image. Often, this correction is part of the camera function (and so each

275 element of U can be taken as unity). Sometimes, the correction matrix can be provided by the

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276 detector supplier. In other cases, the correction matrix shall be determined by the procedure

277 outlined in Clause A2.

278 Detectors can have invalid pixels, which are pixels whose corrected conversion efficiency

279 excee
...