IEC 60793-1-46:2024

Optical fibres - Part 1-46: Measurement methods and test procedures - Monitoring of changes in attenuation

IEC 60793-1-46:2024 establishes uniform requirements for the monitoring of changes in attenuation, thereby assisting in the inspection of fibres and cables for commercial purposes. This document gives two methods for monitoring the changes in attenuation of optical fibres and cables that occur during mechanical or environmental testing, or both. It provides a monitor in the change of attenuation characteristics arising from optical discontinuity, physical defects and modifications of the attenuation slope:
- method A: change in attenuation by transmitted power;
- method B: change in attenuation by backscattering.
Methods A and B apply to the monitoring of all categories of the following fibres:
- class A: multimode fibres;
- class B: single-mode fibres;
- class C: single-mode intraconnection fibres.
Information common to both measurements is contained in Clause 1 to Clause 10, and information pertaining to each individual method appears in Annex A, and Annex B respectively.

Fibres optiques - Partie 1-46: Méthodes de mesure et procédures d’essai - Contrôle des variations de l’affaiblissement

L’IEC 60793-1-46:2024 établit des exigences uniformes pour le contrôle des variations de l’affaiblissement, contribuant ainsi au contrôle des fibres et câbles dans le cadre des relations commerciales. Le présent document décrit deux méthodes pour contrôler les variations de l’affaiblissement des fibres optiques et des câbles qui se produisent au cours des essais mécaniques et d’environnement, ou des deux. Il fournit un moyen de contrôle de la variation des caractéristiques d’affaiblissement qui proviennent de la discontinuité optique, de défauts physiques et de modifications de la pente d’affaiblissement:
- Méthode A: variation de l’affaiblissement en puissance transmise;
- Méthode B : variation de l’affaiblissement en rétrodiffusion.
Les méthodes A et B s’appliquent au contrôle de toutes les catégories de fibres suivantes:
- Classe A: fibres multimodales;
- Classe B: fibres unimodales;
- Classe C: fibres d’intraconnexion unimodales.
Les informations communes aux deux mesures sont contenues dans les Articles 1 à 10 et les informations relatives à chacune des méthodes se trouvent respectivement dans les Annexe A et Annexe B.

General Information

• Status: Published
• Publication Date: 26-Jun-2024
• ICS: 33.180.10 - Fibres and cables
• Technical Committee: SC 86A - Fibres and cables
• Drafting Committee: WG 1 - TC 86/SC 86A/WG 1
• Current Stage: PPUB - Publication issued
• Start Date: 27-Jun-2024
• Completion Date: 19-Jul-2024

Relations

• Revises: IEC 60793-1-46:2001 - Optical fibres - Part 1-46: Measurement methods and test procedures - Monitoring of changes in optical transmittance
• Effective Date: 05-Sep-2023

Overview

IEC 60793-1-46:2024 - Optical fibres: Measurement methods and test procedures - Monitoring of changes in attenuation - defines standardized methods to monitor changes in optical attenuation during mechanical and environmental testing. The standard supports commercial inspection of fibres and cables by describing two complementary monitoring techniques: Method A (transmitted power) and Method B (backscattering). It applies to all fibre categories covered: class A (multimode), class B (single‑mode) and class C (single‑mode intraconnection).

Key topics and requirements

• Scope and purpose: Establishes uniform requirements for detecting changes in attenuation caused by optical discontinuities, physical defects or shifts in attenuation slope.
• Two monitoring methods:
  • Method A - change in attenuation by transmitted power (normative Annex A): uses a reference path, stabilized sources, launch apparatus and detectors to track transmitted optical power changes.
  • Method B - change in attenuation by backscattering (normative Annex B): uses backscatter measurement techniques to identify localised or distributed loss changes.
• Common measurement provisions (Clauses 1–10): include apparatus, sampling, specimen preparation, procedures, calculations, results and required reporting.
• Specimen requirements:
  • Minimum specimen length must ensure changes are resolvable by the chosen method and apparatus.
  • End faces must be flat and orthogonal to the fibre axis.
  • When used, a reference specimen sample must be identical in type and stable throughout the test.
• Reporting and calculations: Defines required information to be provided with each measurement and additional data available on request (see Clauses 8–10).
• Illustrative layouts and equipment lists: Annexes include layout drawings and specific apparatus requirements for each method.

Applications and users

IEC 60793-1-46:2024 is practical for:

• Fibre and cable manufacturers - in-line quality control and qualification during environmental or mechanical stress testing.
• Test laboratories and QA teams - standardized procedures for comparative acceptance tests and commercial inspections.
• R&D and product development - evaluating design changes that affect attenuation slope or discontinuities.
• Installers and field engineers - diagnosing degradation mechanisms when combined with other OTDR or attenuation tests.
• Certification bodies - consistent test methods for compliance and contract verification.

Keywords: IEC 60793-1-46:2024, optical fibres, monitoring changes in attenuation, transmitted power, backscattering, method A, method B, multimode, single‑mode, intraconnection, test procedures, measurement methods.

Related standards

• IEC 60793-1-40 - Attenuation measurement methods (referenced normative)
• Other parts of the IEC 60793-1-4X series (1‑40 to 1‑49) cover related transmission and optical characteristic tests (bandwidth, dispersion, numerical aperture, macrobending, etc.).

Standards Content (Sample)

IEC 60793-1-46 ®
Edition 2.0 2024-06
COMMENTED VERSION
INTERNATIONAL
STANDARD
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Optical fibres –
Part 1-46: Measurement methods and test procedures – Monitoring of changes
in attenuation
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IEC 60793-1-46 ®
Edition 2.0 2024-06
COMMENTED VERSION
INTERNATIONAL
STANDARD
colour
inside
Optical fibres –
Part 1-46: Measurement methods and test procedures – Monitoring of changes
in attenuation
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 33.180.10 ISBN 978-2-8322-9348-5
– 2 – IEC 60793-1-46:2024 CMV © IEC 2024
CONTENTS
FOREWORD .3
INTRODUCTION .6
1 Scope .7
2 Normative references .7
3 Terms and definitions .7
4 Reference test method .7
5 Apparatus .8
6 Sampling and specimens .8
6.1 Specimen Sample length .8
6.2 Specimen Sample end face .8
6.3 Specimen Sample preparation .8
6.4 Reference specimen sample .8
7 Procedure .8
8 Calculations .8
9 Results .8
9.1 Information to be provided with each measurement .8
9.2 Information available upon request .9
10 Specification information .9
Annex A (normative) Requirements specific to method A – Change in transmittance
attenuation by transmitted power . 10
A.1 Apparatus. 10
A.1.1 General . 10
A.1.2 Optical source . 10
A.1.3 Optical divider . 10
A.1.4 Optical detector . 10
A.1.5 Launch apparatus . 12
A.2 Procedure . 12
A.3 Calculations . 13
Annex B (normative) Requirements specific to method B – Change in transmittance
attenuation by backscattering . 14
B.1 Apparatus. 14
B.2 Procedure . 14
B.3 Calculations . 14
List of comments . 15

Figure A.1 – Measurement of change in optical transmittance attenuation using
reference specimen sample . 11
Figure A.2 – Measurement of change in optical transmittance attenuation using
stabilized source . 12

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPTICAL FIBRES –
Part 1-46: Measurement methods and test procedures –
Monitoring of changes in optical transmittance attenuation

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,
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shall not be held responsible for identifying any or all such patent rights.
This commented version (CMV) of the official standard IEC 60793-1-46:2024 edition 2.0
allows the user to identify the changes made to the previous IEC 60793-1-46:2001
edition 1.0. Furthermore, comments from IEC SC 86A experts are provided to explain the
reasons of the most relevant changes, or to clarify any part of the content.
A vertical bar appears in the margin wherever a change has been made. Additions are in
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This publication contains the CMV and the official standard. The full list of comments is
available at the end of the CMV.

– 4 – IEC 60793-1-46:2024 CMV © IEC 2024
IEC 60793-1-46 has been prepared by subcommittee 86A: Fibres and cables, of IEC technical
committee 86: Fibre optics. It is an International Standard.
This second edition cancels and replaces the first edition published in 2001. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) inclusion of class C single mode intraconnection fibre;
b) replacement of 'optical transmittance' by 'attenuation'.
The text of this International Standard is based on the following documents:
Draft Report on voting
86A/2442/FDIS 86A/2475/RVD
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.
IEC 60793-1-1 and IEC 60793-1-2 cover generic specifications.
IEC 60793-1-4X consists of the following parts, under the general title: Optical fibres:
– Part 1-40: Measurement methods and test procedures – Attenuation
– Part 1-41: Measurement methods and test procedures – Bandwidth
– Part 1-42: Measurement methods and test procedures – Chromatic dispersion
– Part 1-43: Measurement methods and test procedures – Numerical aperture
– Part 1-44: Measurement methods and test procedures – Cut-off wavelength
– Part 1-45: Measurement methods and test procedures – Mode field diameter
– Part 1-46: Measurement methods and test procedures – Monitoring of changes in
attenuation
– Part 1-47: Measurement methods and test procedures – Macrobending loss
– Part 1-48: Measurement methods and test procedures – Polarization mode dispersion
– Part 1-49: Measurement methods and test procedures – Differential mode delay
A list of all parts in the IEC 60793 series, published under the general title Optical fibres, can
be found 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, or
• revised.
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.

– 6 – IEC 60793-1-46:2024 CMV © IEC 2024
INTRODUCTION
Publications in the IEC 60793-1 series concern measurement methods and test procedures as
they apply to optical fibres.
Within the same series several different areas are grouped, as follows:
– parts 1-10 to 1-19: General
– IEC 60793-1-20 to IEC 60793-1-29: Measurement methods and test procedures for
dimensions
– IEC 60793-1-30 to IEC 60793-1-39: Measurement methods and test procedures for
mechanical characteristics
– IEC 60793-1-40 to IEC 60793-1-49: Measurement methods and test procedures for
transmission and optical characteristics
– IEC 60793-1-50 to IEC 60793-1-59: Measurement methods and test procedures for
environmental characteristics
– IEC 60793-1-60 to IEC 60793-1-69: Measurement methods and test procedures for
polarization-maintaining fibres

OPTICAL FIBRES –
Part 1-46: Measurement methods and test procedures –
Monitoring of changes in optical transmittance attenuation 1

1 Scope
This part of IEC 60793 establishes uniform requirements for the monitoring of changes in optical
transmittance attenuation, thereby assisting in the inspection of fibres and cables for
commercial purposes.
This document gives two methods for monitoring the changes in optical transmittance
attenuation of optical fibres and cables that occur during mechanical or environmental testing,
or both. It provides a monitor in the change of optical transmission attenuation characteristics
arising from optical discontinuity, physical defects and modifications of the attenuation slope:
– method A: change in transmittance attenuation by transmitted power;
– method B: change in transmittance attenuation by backscattering.
Methods A and B apply to the monitoring of all categories of the following fibres:
– class A: multimode fibres;
– class B: single-mode fibres;
– class C: single-mode intraconnection fibres. 2
Information common to both measurements is contained in Clause 1 to Clause 10, and
information pertaining to each individual method appears in Annex A, and Annex B respectively.
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 60793-1-40, Optical fibres – Part 1-40: Measurement methods and test procedures –
Attenuation measurement methods
3 Terms and definitions
No terms and definitions are listed in this document.
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
4 Reference test method
Under consideration.
– 8 – IEC 60793-1-46:2024 CMV © IEC 2024
There are no reference test methods indicated in this document. 3
5 Apparatus
Annex A and Annex B include layout drawings and other equipment requirements that
individually apply for each of the methods, respectively.
6 Sampling and specimens 4
6.1 Specimen Sample length
The minimum length of the specimen sample shall be such that the changes in attenuation are
compatible with the resolution of the applicable test method (method A or method B),
measurement apparatus, and the non-linearities at the beginning and end of it shall not affect
the results.
6.2 Specimen Sample end face
Prepare a flat end face, orthogonal to the fibre axis, at the input and output ends of each
specimen sample.
6.3 Specimen Sample preparation
Prepare the specimen sample as described in the appropriate mechanical, environmental, or
other test method specified.
6.4 Reference specimen sample
In methods where a reference specimen sample is used, it shall comprise an identical kind of
optical fibre or cable to the specimen sample and shall be linked between the optical divider
and detector, as shown in Figure A.1. It may can be a short length of fibre. The condition of the
reference specimen sample shall be constant during the whole test.
7 Procedure
For individual procedures, see appropriate annex: Annex A and Annex B, respectively.
8 Calculations
For calculation procedures, see the appropriate annex: Annex A and Annex B, respectively.
9 Results
9.1 Information to be provided with each measurement
Report the following information with each measurement:
– date and title of measurement;
– identification of specimen sample;
– optical source wavelength, λ;
– specimen sample length;
– conditions of the environment and measurement equipment;

– changes in optical transmittance, D attenuation, A ; n = 1,2,3, . preferably plotted in a
η n
graph versus test parameters.
9.2 Information available upon request
The following information shall be available upon request:
– measurement method used: A or B;
– type of optical source used and its spectral width (FWHM);
– launching technique used;
– description of all key equipment;
– details of computation technique;
– date of latest calibration of measurement equipment.
10 Specification information
The detail specification shall specify the following information:
– type of fibre to be measured;
– failure or acceptance criteria;
– information to be reported;
– any deviations from the procedure that apply.

– 10 – IEC 60793-1-46:2024 CMV © IEC 2024
Annex A
(normative)
Requirements specific to method A –
Change in transmittance attenuation by transmitted power
A.1 Apparatus
A.1.1 General
The arrangement shall provide a monitoring for optical transmittance attenuation with high
resolution and good stability over the time and temperature changes given in the relevant
product specification.
Figure A.1 is an example of a typical arrangement suitable for use when carrying out mechanical
or environmental tests in a laboratory or factory. By comparison with a reference sample, it
provides a measurement of the change in optical transmittance attenuation, corrected for any
changes that might occur in the optical source. Connections shall have stable coupling
conditions.
Figure A.2 is an example of a typical arrangement suitable for use in the field, laboratory, or
factory where long-term tests are required, in cases where it is possible to stabilize the optical
source by optical feedback. If the stability of the optical source is compatible with the accuracy
necessary for the measurement, then the insertion loss measurement method (method B of
IEC 60793-1-40) may can be used.
A.1.2 Optical source
Use a suitable source such as a laser or light-emitting diode, emitting at wavelengths compatible
with the optical fibres under test. It is customary to modulate the optical source and wavelength
selective optical filters may can be used.
A.1.3 Optical divider
The optical divider shall have a splitting ratio that remains constant during the test. The splitting
ratio and temperature stability shall be as shown in the relevant detail specification.
Commercially available or custom-built devices may can be used.
A.1.4 Optical detector
The optical detector shall be of sufficient area to intercept all of the radiated power in the output
cone and shall be sufficiently linear over the optical powers encountered.

Figure A.1 – Measurement of change in optical transmittance attenuation using
reference specimen sample
– 12 – IEC 60793-1-46:2024 CMV © IEC 2024
IEC  705/01
Figure A.2 – Measurement of change in optical transmittance attenuation using
stabilized source
The optical detector shall have a sufficiently uniform response over the active area and range
of incidence angle at the measurement wavelength to ensure the movement of the output cone
in position or angle relative to the detector. This shall be within the limits determined by the
mechanical design of the measurement equipment and shall not significantly affect the results.
Where more than one detector is used, as in the arrangement shown in Figure A.1, the detectors
shall be of the same manufacturer and model and be of comparable linearity.
A.1.5 Launch apparatus
Provide apparatus to produce a full or restricted launch, depending on the parameter being
measured, with conditions as shown in IEC 60793-1-40, methods A and B, for both multimode
and single-mode fibre. Use cladding mode strippers at the source and detector ends of the
specimen sample, and of the reference specimen sample if used.
A.2 Procedure
Before the test sequence, measure the initial optical power, P from the test specimen sample
0t,
and, in the case of Figure A.1, the initial optical output power, P , from the reference specimen
0r
sample.
During the test sequence specified in the appropriate mechanical, environmental, or other test
being carried out, measure the subsequent optical output powers, P (n = 1, 2, 3, .), from the
nt
test specimen sample and, in the case of Figure A.1, the subsequent powers, P , from the
nr
reference specimen sample.
In the above measurements, quantities proportional to the absolute power, rather than the
absolute powers themselves, may can be measured. In the case of Figure A.1, the
proportionality factor may can differ between the test and reference channels. The
proportionality factor(s) shall remain constant for the duration of the test sequence.
A.3 Calculations 5
Calculate the changes in optical transmittance attenuation during the test sequence (in
decibels)
for Figure A.1:
P × P
0r nt
D = 10 log
n 10
P × P
0t nr
A = 10 log PP× / P ×P
(( ) ( )) (A.1)
n 10 0t nr 0r nt
for Figure A.2:
P
nt
D = 10 log
n 10
P
0t
A = 10 log PP/
( ) (A.2)
n 10 0t nt
where
D A is the change in optical transmittance attenuation during the sequence, in dB;
n
n
P
is the initial optical output power from the test specimen sample, in mW;
0t
P is the initial optical output power from the reference specimen sample, in mW;
0r
P is the subsequent optical output power from the test specimen sample, in mW;
nt
P is the subsequent optical output power from the reference specimen sample, in mW.
nr
– 14 – IEC 60793-1-46:2024 CMV © IEC 2024
Annex B
(normative)
Requirements specific to method B –
Change in transmittance attenuation by backscattering
B.1 Apparatus
See IEC 60793-1-40, method C – Backscattering.
B.2 Procedure
B.2.1 Align the fibre under test to the coupling device.
B.2.2 Analyse the backscattering power by a signal processor and record it on a logarithmic
scale.
B.2.3 Choose two points, A and B, on the curve corresponding to the beginning and the end
of the fibre or cable under test.
B.2.4 If necessary, make measurements from both sides.
B.2.5 Record the following values:
– initial power levels P and P at points A and B (dB);
A0 B0
– subsequent power levels P and P at points A and B (dB).
An Bn
B.2.6 Record the aspects of the curves for comparison before, at intervals during, and after
the test sequence, as specified.
B.3 Calculations 6
For smooth backscattering curves, determine the change in attenuation at the different intervals
of the loss curve by the difference:
D = (P − P ) − (P − P )
n A0 B0 An Bn
A = (P−P )(−−PP )
(B.1)
n An Bn A0 B0
In other cases, take care in the interpretation of the results.
For a more detailed interpretation of results of backscattering, see IEC 60793-1-40, C.5.

List of comments
1 “Change in attenuation” is a commonly used term in many IEC 60794 and IEC 60793 series
standards while referring to IEC 60793-1-46. For consistency, “optical transmittance” is
replaced by “attenuation”.
2 IEC 60793-1-46:2001 was published before IEC 60793-2-60:2008 specifying category C
single mode fibre. IEC 60793-2-60 refers to IEC 60793-1-46 for measuring change in
attenuation. Therefore, category C fibre is included in this revision.
3 The test method either A or B to be selected based on the length of the samples available
for measurement, measurement accuracy or any other measurement conditions. Most
preferred method is depending on these conditions. Typically, for shorter length samples
Method A is preferred. For example, IEC 60794-1-104 specifies to use Method A of
IEC 60793-1-46.
4 “Specimen” is a word normally used in the biological area, usually indicating an individual
animal, plant, piece of a mineral, etc., used as an example of its species or type for
scientific study or display. Working group experts reach an agreement to use “sample”
instead of “specimen” for optical fibre related standards.
5 Equations A.1 and A.2 are revised in accordance with the definition of attenuation replacing
optical transmittance.
6 Equation B.1 is revised in accordance with the definition of attenuation replacing optical
transmittance.
___________
IEC 60793-1-46 ®
Edition 2.0 2024-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Optical fibres –
Part 1-46: Measurement methods and test procedures – Monitoring of changes
in attenuation
Fibres optiques –
Partie 1-46: Méthodes de mesure et procédures d’essai – Contrôle des variations
de l’affaiblissement
– 2 – IEC 60793-1-46:2024 © IEC 2024
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Reference test method . 6
5 Apparatus . 7
6 Sampling . 7
6.1 Sample length . 7
6.2 Sample end face . 7
6.3 Sample preparation . 7
6.4 Reference sample . 7
7 Procedure . 7
8 Calculations . 7
9 Results . 7
9.1 Information to be provided with each measurement . 7
9.2 Information available upon request . 8
10 Specification information . 8
Annex A (normative) Requirements specific to method A – Change in attenuation by
transmitted power . 9
A.1 Apparatus . 9
A.1.1 General . 9
A.1.2 Optical source . 9
A.1.3 Optical divider . 9
A.1.4 Optical detector . 9
A.1.5 Launch apparatus . 10
A.2 Procedure . 10
A.3 Calculations . 11
Annex B (normative) Requirements specific to method B – Change in attenuation by
backscattering . 12
B.1 Apparatus . 12
B.2 Procedure . 12
B.3 Calculations . 12

Figure A.1 – Measurement of change in attenuation using reference sample . 10
Figure A.2 – Measurement of change in attenuation using stabilized source . 10

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPTICAL FIBRES –
Part 1-46: Measurement methods and test procedures –
Monitoring of changes in attenuation

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) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 60793-1-46 has been prepared by subcommittee 86A: Fibres and cables, of IEC technical
committee 86: Fibre optics. It is an International Standard.
This second edition cancels and replaces the first edition published in 2001. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) inclusion of class C single mode intraconnection fibre;
b) replacement of 'optical transmittance' by 'attenuation'.

– 4 – IEC 60793-1-46:2024 © IEC 2024
The text of this International Standard is based on the following documents:
Draft Report on voting
86A/2442/FDIS 86A/2475/RVD
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.
IEC 60793-1-1 and IEC 60793-1-2 cover generic specifications.
IEC 60793-1-4X consists of the following parts, under the general title: Optical fibres:
– Part 1-40: Measurement methods and test procedures – Attenuation
– Part 1-41: Measurement methods and test procedures – Bandwidth
– Part 1-42: Measurement methods and test procedures – Chromatic dispersion
– Part 1-43: Measurement methods and test procedures – Numerical aperture
– Part 1-44: Measurement methods and test procedures – Cut-off wavelength
– Part 1-45: Measurement methods and test procedures – Mode field diameter
– Part 1-46: Measurement methods and test procedures – Monitoring of changes in
attenuation
– Part 1-47: Measurement methods and test procedures – Macrobending loss
– Part 1-48: Measurement methods and test procedures – Polarization mode dispersion
– Part 1-49: Measurement methods and test procedures – Differential mode delay
A list of all parts in the IEC 60793 series, published under the general title Optical fibres, can
be found 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, or
• revised.
INTRODUCTION
Publications in the IEC 60793-1 series concern measurement methods and test procedures as
they apply to optical fibres.
Within the same series several different areas are grouped, as follows:
– IEC 60793-1-20 to IEC 60793-1-29: Measurement methods and test procedures for
dimensions
– IEC 60793-1-30 to IEC 60793-1-39: Measurement methods and test procedures for
mechanical characteristics
– IEC 60793-1-40 to IEC 60793-1-49: Measurement methods and test procedures for
transmission and optical characteristics
– IEC 60793-1-50 to IEC 60793-1-59: Measurement methods and test procedures for
environmental characteristics
– IEC 60793-1-60 to IEC 60793-1-69: Measurement methods and test procedures for
polarization-maintaining fibres

– 6 – IEC 60793-1-46:2024 © IEC 2024
OPTICAL FIBRES –
Part 1-46: Measurement methods and test procedures –
Monitoring of changes in attenuation

1 Scope
This part of IEC 60793 establishes uniform requirements for the monitoring of changes in
attenuation, thereby assisting in the inspection of fibres and cables for commercial purposes.
This document gives two methods for monitoring the changes in attenuation of optical fibres
and cables that occur during mechanical or environmental testing, or both. It provides a monitor
in the change of attenuation characteristics arising from optical discontinuity, physical defects
and modifications of the attenuation slope:
– method A: change in attenuation by transmitted power;
– method B: change in attenuation by backscattering.
Methods A and B apply to the monitoring of all categories of the following fibres:
– class A: multimode fibres;
– class B: single-mode fibres;
– class C: single-mode intraconnection fibres.
Information common to both measurements is contained in Clause 1 to Clause 10, and
information pertaining to each individual method appears in Annex A, and Annex B respectively.
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 60793-1-40, Optical fibres – Part 1-40: Attenuation measurement methods
3 Terms and definitions
No terms and definitions are listed in this document.
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
4 Reference test method
There are no reference test methods indicated in this document.

5 Apparatus
Annex A and Annex B include layout drawings and other equipment requirements that
individually apply for each of the methods, respectively.
6 Sampling
6.1 Sample length
The minimum length of the sample shall be such that the changes in attenuation are compatible
with the resolution of the applicable test method (method A or method B), measurement
apparatus, and the non-linearities at the beginning and end of it shall not affect the results.
6.2 Sample end face
Prepare a flat end face, orthogonal to the fibre axis, at the input and output ends of each sample.
6.3 Sample preparation
Prepare the sample as described in the appropriate mechanical, environmental, or other test
method specified.
6.4 Reference sample
In methods where a reference sample is used, it shall comprise an identical kind of optical fibre
or cable to the sample and shall be linked between the optical divider and detector, as shown
in Figure A.1. It can be a short length of fibre. The condition of the reference sample shall be
constant during the whole test.
7 Procedure
For individual procedures, see appropriate annex: Annex A and Annex B, respectively.
8 Calculations
For calculation procedures, see the appropriate annex: Annex A and Annex B, respectively.
9 Results
9.1 Information to be provided with each measurement
Report the following information with each
...

IEC 60793-1-46 ®
Edition 2.0 2024-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Optical fibres –
Part 1-46: Measurement methods and test procedures – Monitoring of changes
in attenuation
Fibres optiques –
Partie 1-46: Méthodes de mesure et procédures d’essai – Contrôle des variations
de l’affaiblissement
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IEC 60793-1-46 ®
Edition 2.0 2024-06
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
Optical fibres –
Part 1-46: Measurement methods and test procedures – Monitoring of changes in

attenuation
Fibres optiques –
Partie 1-46: Méthodes de mesure et procédures d’essai – Contrôle des variations

de l’affaiblissement
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.180.10 ISBN 978-2-8322-9194-8

– 2 – IEC 60793-1-46:2024 © IEC 2024
CONTENTS
FOREWORD . 3
INTRODUCTION . 5
1 Scope . 6
2 Normative references . 6
3 Terms and definitions . 6
4 Reference test method . 6
5 Apparatus . 7
6 Sampling . 7
6.1 Sample length . 7
6.2 Sample end face . 7
6.3 Sample preparation . 7
6.4 Reference sample . 7
7 Procedure . 7
8 Calculations . 7
9 Results . 7
9.1 Information to be provided with each measurement . 7
9.2 Information available upon request . 8
10 Specification information . 8
Annex A (normative) Requirements specific to method A – Change in attenuation by
transmitted power . 9
A.1 Apparatus . 9
A.1.1 General . 9
A.1.2 Optical source . 9
A.1.3 Optical divider . 9
A.1.4 Optical detector . 9
A.1.5 Launch apparatus . 10
A.2 Procedure . 10
A.3 Calculations . 11
Annex B (normative) Requirements specific to method B – Change in attenuation by
backscattering . 12
B.1 Apparatus . 12
B.2 Procedure . 12
B.3 Calculations . 12

Figure A.1 – Measurement of change in attenuation using reference sample . 10
Figure A.2 – Measurement of change in attenuation using stabilized source . 10

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
OPTICAL FIBRES –
Part 1-46: Measurement methods and test procedures –
Monitoring of changes in attenuation

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) IEC draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). IEC takes no position concerning the evidence, validity or applicability of any claimed patent rights in
respect thereof. As of the date of publication of this document, IEC had not received notice of (a) patent(s), which
may be required to implement this document. However, implementers are cautioned that this may not represent
the latest information, which may be obtained from the patent database available at https://patents.iec.ch. IEC
shall not be held responsible for identifying any or all such patent rights.
IEC 60793-1-46 has been prepared by subcommittee 86A: Fibres and cables, of IEC technical
committee 86: Fibre optics. It is an International Standard.
This second edition cancels and replaces the first edition published in 2001. This edition
constitutes a technical revision.
This edition includes the following significant technical changes with respect to the previous
edition:
a) inclusion of class C single mode intraconnection fibre;
b) replacement of 'optical transmittance' by 'attenuation'.

– 4 – IEC 60793-1-46:2024 © IEC 2024
The text of this International Standard is based on the following documents:
Draft Report on voting
86A/2442/FDIS 86A/2475/RVD
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.
IEC 60793-1-1 and IEC 60793-1-2 cover generic specifications.
IEC 60793-1-4X consists of the following parts, under the general title: Optical fibres:
– Part 1-40: Measurement methods and test procedures – Attenuation
– Part 1-41: Measurement methods and test procedures – Bandwidth
– Part 1-42: Measurement methods and test procedures – Chromatic dispersion
– Part 1-43: Measurement methods and test procedures – Numerical aperture
– Part 1-44: Measurement methods and test procedures – Cut-off wavelength
– Part 1-45: Measurement methods and test procedures – Mode field diameter
– Part 1-46: Measurement methods and test procedures – Monitoring of changes in
attenuation
– Part 1-47: Measurement methods and test procedures – Macrobending loss
– Part 1-48: Measurement methods and test procedures – Polarization mode dispersion
– Part 1-49: Measurement methods and test procedures – Differential mode delay
A list of all parts in the IEC 60793 series, published under the general title Optical fibres, can
be found 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, or
• revised.
INTRODUCTION
Publications in the IEC 60793-1 series concern measurement methods and test procedures as
they apply to optical fibres.
Within the same series several different areas are grouped, as follows:
– IEC 60793-1-20 to IEC 60793-1-29: Measurement methods and test procedures for
dimensions
– IEC 60793-1-30 to IEC 60793-1-39: Measurement methods and test procedures for
mechanical characteristics
– IEC 60793-1-40 to IEC 60793-1-49: Measurement methods and test procedures for
transmission and optical characteristics
– IEC 60793-1-50 to IEC 60793-1-59: Measurement methods and test procedures for
environmental characteristics
– IEC 60793-1-60 to IEC 60793-1-69: Measurement methods and test procedures for
polarization-maintaining fibres

– 6 – IEC 60793-1-46:2024 © IEC 2024
OPTICAL FIBRES –
Part 1-46: Measurement methods and test procedures –
Monitoring of changes in attenuation

1 Scope
This part of IEC 60793 establishes uniform requirements for the monitoring of changes in
attenuation, thereby assisting in the inspection of fibres and cables for commercial purposes.
This document gives two methods for monitoring the changes in attenuation of optical fibres
and cables that occur during mechanical or environmental testing, or both. It provides a monitor
in the change of attenuation characteristics arising from optical discontinuity, physical defects
and modifications of the attenuation slope:
– method A: change in attenuation by transmitted power;
– method B: change in attenuation by backscattering.
Methods A and B apply to the monitoring of all categories of the following fibres:
– class A: multimode fibres;
– class B: single-mode fibres;
– class C: single-mode intraconnection fibres.
Information common to both measurements is contained in Clause 1 to Clause 10, and
information pertaining to each individual method appears in Annex A, and Annex B respectively.
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 60793-1-40, Optical fibres – Part 1-40: Attenuation measurement methods
3 Terms and definitions
No terms and definitions are listed in this document.
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
4 Reference test method
There are no reference test methods indicated in this document.

5 Apparatus
Annex A and Annex B include layout drawings and other equipment requirements that
individually apply for each of the methods, respectively.
6 Sampling
6.1 Sample length
The minimum length of the sample shall be such that the changes in attenuation are compatible
with the resolution of the applicable test method (method A or method B), measurement
apparatus, and the non-linearities at the beginning and end of it shall not affect the results.
6.2 Sample end face
Prepare a flat end face, orthogonal to the fibre axis, at the input and output ends of each sample.
6.3 Sample preparation
Prepare the sample as described in the appropriate mechanical, environmental, or other test
method specified.
6.4 Reference sample
In methods where a reference sample is used, it shall comprise an identical kind of optical fibre
or cable to the sample and shall be linked between the optical divider and detector, as shown
in Figure A.1. It can be a short length of fibre. The condition of the reference sample shall be
constant during the whole test.
7 Procedure
For individual procedures, see appropriate annex: Annex A and Annex B, respectively.
8 Calculations
For calculation procedures, see the appropriate annex: Annex A and Annex B, respectively.
9 Results
9.1 Information to be provided with each measurement
Report the following information with each measurement:
– date and title of measurement;
– identification of sample;
– optical source wavelength, λ;
– sample length;
– conditions of the environment and measurement equipment;
– changes in attenuation, A ; n = 1,2,3, . preferably plotted in a graph versus test
n
parameters.
– 8 – IEC 60793-1-46:2024 © IEC 2024
9.2 Information available upon request
The following information shall be available upon request:
– measurement method used: A or B;
– type of optical source used and its spectral width (FWHM);
– launching technique used;
– description of all key equipment;
– details of computation technique;
– date of latest calibration of measurement equipment.
10 Specification information
The detail specification shall specify the following information:
– type of fibre to be measured;
– failure or acceptance criteria;
– information to be reported;
– any deviations from the procedure that apply.

Annex A
(normative)
Requirements specific to method A –
Change in attenuation by transmitted power
A.1 Apparatus
A.1.1 General
The arrangement shall provide a monitoring for attenuation with high resolution and good
stability over the time and temperature changes given in the relevant product specification.
Figure A.1 is an example of a typical arrangement suitable for use when carrying out mechanical
or environmental tests in a laboratory or factory. By comparison with a reference sample, it
provides a measurement of the change in attenuation, corrected for any changes that might
occur in the optical source. Connections shall have stable coupling conditions.
Figure A.2 is an example of a typical arrangement suitable for use in the field, laboratory, or
factory where long-term tests are required, in cases where it is possible to stabilize the optical
source by optical feedback. If the stability of the optical source is compatible with the accuracy
necessary for the measurement, then the insertion loss measurement method (method B of
IEC 60793-1-40) can be used.
A.1.2 Optical source
Use a suitable source such as a laser or light-emitting diode, emitting at wavelengths compatible
with the optical fibres under test. It is customary to modulate the optical source and wavelength
selective optical filters can be used.
A.1.3 Optical divider
The optical divider shall have a splitting ratio that remains constant during the test. The splitting
ratio and temperature stability shall be as shown in the relevant detail specification.
Commercially available or custom-built devices can be used.
A.1.4 Optical detector
The optical detector shall be of sufficient area to intercept all of the radiated power in the output
cone and shall be sufficiently linear over the optical powers encountered.

– 10 – IEC 60793-1-46:2024 © IEC 2024

Figure A.1 – Measurement of change in attenuation using reference sample

Figure A.2 – Measurement of change in attenuation using stabilized source
The optical detector shall have a sufficiently uniform response over the active area and range
of incidence angle at the measurement wavelength to ensure the movement of the output cone
in position or angle relative to the detector. This shall be within the limits determined by the
mechanical design of the measurement equipment and shall not significantly affect the results.
Where more than one detector is used, as in the arrangement shown in Figure A.1, the detectors
shall be of the same manufacturer and model and be of comparable linearity.
A.1.5 Launch apparatus
Provide apparatus to produce a full or restricted launch, depending on the parameter being
measured, with conditions as shown in IEC 60793-1-40, methods A and B, for both multimode
and single-mode fibre. Use cladding mode strippers at the source and detector ends of the
sample, and of the reference sample if used.
A.2 Procedure
Before the test sequence, measure the initial optical power, P from the test sample and, in
0t,
the case of Figure A.1, the initial optical output power, P , from the reference sample.
0r
During the test sequence specified in the appropriate mechanical, environmental, or other test
being carried out, measure the subsequent optical output powers, P (n = 1, 2, 3, .), from the
nt
test sample and, in the case of Figure A.1, the subsequent powers, P , from the reference
nr
sample.
In the above measurements, quantities proportional to the absolute power, rather than the

absolute powers themselves, can be measured. In the case of Figure A.1, the proportionality
factor can differ between the test and reference channels. The proportionality factor(s) shall
remain constant for the duration of the test sequence.
A.3 Calculations
Calculate the changes in attenuation during the test sequence
for Figure A.1:
A = 10 log PP× / P ×P
(( ) ( ))
(A.1)
n 10 0t nr 0r nt
for Figure A.2:
A = 10 log PP/
( ) (A.2)
n 10 0t nt
wher
...