SIST EN 60793-1-22:2004
(Main)Optical fibres -- Part 1-22: Measurement methods and test procedures - Length measurement
Optical fibres -- Part 1-22: Measurement methods and test procedures - Length measurement
Gives methods for measuring the length and elongation of optical fibres (typically within a cable). Length is fundemental for evaluation of transmission characteristics such as losses and bandwidths. Five methods are described: delay measurement, backscattering, fibre elongation, mechanical length, and phase shift.
Lichtwellenleiter -- Teil 1-22: Messmethoden und Prüfverfahren - Längenmessung
Fibres optiques -- Partie 1-22: Méthodes de mesure et procédures d'essai - Mesure de la longueur
Etablit des méthodes pour mesurer la longueur et l'allongement des fibres optiques (typiquement dans un câble). La longueur est fondamentale pour l'évaluation des caractéristiques de transmission telles que les pertes et la bande passante. Cinq méthodes sont décrites: mesure du retard, rétrodiffusion, allongement de la fibre, longueur mécanique, et déphasage.
Optična vlakna – 1-22. del: Metode merjenja in preskusni postopki - Merjenje dolžine (IEC 60793-1-22:2001)*
General Information
Relations
Standards Content (Sample)
SLOVENSKI SIST EN 60793-1-22:2004
STANDARD
september 2004
Optična vlakna – 1-22. del: Metode merjenja in preskusni postopki - Merjenje
dolžine (IEC 60793-1-22:2001)*
Optical fibres - Part 1-22: Measurement methods and test procedures - Length
measurement (IEC 60793-1-22:2001)
ICS 33.180.10 Referenčna številka
SIST EN 60793-1-22:2004(en)
© Standard je založil in izdal Slovenski inštitut za standardizacijo. Razmnoževanje ali kopiranje celote ali delov tega dokumenta ni dovoljeno
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EUROPEAN STANDARD EN 60793-1-22
NORME EUROPÉENNE
EUROPÄISCHE NORM March 2002
ICS 33.180.10 Partly supersedes EN 188000:1992
English version
Optical fibres
Part 1-22: Measurement methods and test procedures –
Length measurement
(IEC 60793-1-22:2001)
Fibres optiques Lichtwellenleiter
Partie 1-22: Méthodes de mesure Teil 1-22: Messmethoden
et procédures d'essai – und Prüfverfahren –
Mesure de la longueur Längenmessung
(CEI 60793-1-22:2001) (IEC 60793-1-22:2001)
This European Standard was approved by CENELEC on 2002-03-05. 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 Central Secretariat 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 Central Secretariat has the same status as the official versions.
CENELEC members are the national electrotechnical committees of Austria, Belgium, Czech Republic,
Denmark, Finland, France, Germany, Greece, Iceland, Ireland, Italy, Luxembourg, Malta, Netherlands,
Norway, Portugal, Spain, Sweden, Switzerland and United Kingdom.
CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
Central Secretariat: rue de Stassart 35, B - 1050 Brussels
© 2002 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 60793-1-22:2002 E
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EN 60793-1-22:2002 - 2 -
Foreword
The text of document 86A/687/FDIS, future edition 1 of IEC 60793-1-22, prepared by SC 86A, Fibres
and cables, of IEC TC 86, Fibre optics, was submitted to the IEC-CENELEC parallel vote and was
approved by CENELEC as EN 60793-1-22 on 2002-03-05.
This European Standard supersedes subclause 2.10 (test method 105), subclause 2.11 (test method
106) and subclause 4.7 (test method 303) of EN 188000:1992.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
national standard or by endorsement (dop) 2002-12-01
– latest date by which the national standards conflicting
with the EN have to be withdrawn (dow) 2005-03-01
Annexes designated "normative" are part of the body of the standard.
In this standard, annexes A, B, C, D, E and ZA are normative.
Annex ZA has been added by CENELEC.
Compared to IEC 60793-1:1989 and IEC 60793-2:1992, IEC/SC 86A has adopted a revised structure
of the new IEC 60793 series: The individual measurement methods and test procedures for optical
fibres are published as "Part 1-XX"; the product standards are published as "Part 2-XX".
The general relationship between the new series of EN 60793 and the superseded European
Standards of the EN 188000 series is as follows:
EN Title supersedes
EN 60793-1-XX Optical fibres -- Part 1-XX: Measurement methods Individual subclauses of
and test procedures EN 188000:1992
EN 188100:1995
EN 60793-2-XX Optical fibres -- Part 2-XX: Product specifications
EN 188101:1995
EN 188102:1995
EN 188200:1995
EN 188201:1995
EN 188202:1995
EN 60793-1-2X consists of the following parts, under the general title: Optical fibres:
- Part 1-20: Measurement methods and test procedures – Fibre geometry
- Part 1-21: Measurement methods and test procedures – Coating geometry
- Part 1-22: Measurement methods and test procedures – Length measurement
__________
Endorsement notice
The text of the International Standard IEC 60793-1-22:2001 was approved by CENELEC as a European
Standard without any modification.
__________
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- 3 - EN 60793-1-22:2002
Annex ZA
(normative)
Normative references to international publications
with their corresponding European publications
This European Standard incorporates by dated or undated reference, provisions from other
publications. These normative references are cited at the appropriate places in the text and the
publications are listed hereafter. For dated references, subsequent amendments to or revisions of any
of these publications apply to this European Standard only when incorporated in it by amendment or
revision. For undated references the latest edition of the publication referred to applies (including
amendments).
NOTE When an international publication has been modified by common modifications, indicated by (mod), the relevant
EN/HD applies.
Publication Year Title EN/HD Year
1) 2)
IEC 60793-1-40 - Optical fibres EN 60793-1-40 -
Part 1-40: Measurement methods and
test procedures – Attenuation
1)
3)
IEC 60793-1-42 - Part 1-42: Measurement methods and EN 60793-1-42 2002
test procedures - Chromatic dispersion
1) 3)
IEC 60794-1-1 - Optical fibre cables EN 60794-1-1 2002
Part 1-1: Generic specification - General
1)
Undated reference.
2)
To be published.
3)
Valid edition at date of issue.
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NORME CEI
INTERNATIONALE IEC
60793-1-22
INTERNATIONAL
Première édition
STANDARD
First edition
2001-08
Fibres optiques –
Partie 1-22:
Méthodes de mesure et procédures d'essai –
Mesure de la longueur
Optical fibres –
Part 1-22:
Measurement methods and test procedures –
Length measurement
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microfilms, sans l'accord écrit de l'éditeur. writing from the publisher.
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CODE PRIX
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Pour prix, voir catalogue en vigueur
For price, see current catalogue
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60793-1-22 © IEC:2001 – 3 –
CONTENTS
FOREWORD.7
INTRODUCTION.11
1 Scope.13
2 Normative references.13
3 Overview of method .13
3.1 Method A – Delay measuring .15
3.2 Method B – Backscattering .15
3.3 Method C – Fibre elongation .15
3.4 Method D – Mechanical length .15
3.5 Method E – Phase shift.15
3.6 Reference test method.15
4 Apparatus.15
5 Sampling and specimens .17
6 Procedure.17
7 Calculations.17
8 Results .17
9 Specification information.17
Annex A (normative) Requirements specific to method A – Delay measuring.19
Annex B (normative) Requirements specific to method B – Backscattering.29
Annex C (normative) Requirements specific to method C – Fibre elongation .43
Annex D (normative) Requirements specific to method D – Mechanical length .49
Annex E (normative) Requirements specific to method E – Phase shift .51
Figure A.1 – Time measurement of the transmitted pulse .21
Figure A.2 – Time measurement of the reflected pulse .21
Figure A.3 – Principle of fibre-length measurement.25
Figure B.1 – Block diagram of an OTDR .29
Figure B.2 – Schematic OTDR trace of a specimen (z to z ) with a section
1 0
(e.g. dead-zone fibre) of unknown length, z , preceding it and without a reflection
1
pulse from the fibre joint point (two-point technique (B.4.3.1)).37
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60793-1-22 © IEC:2001 – 5 –
Figure B.3 – Schematic OTDR trace of specimen (z to z ) with a section (e.g. dead-
1 2
zone fibre) of unknown length, z , preceding it and with a reflection pulse from the fibre
1
joint point (two-point technique (B.4.3.1)) .37
Figure B.4 – Schematic trace of a specimen (0 to z ) with no section preceding it
2
(single-point technique (B.4.3.2)).39
Figure B.5 – Schematic OTDR trace of a specimen (z to z ) with a section (e.g. dead-
D 2
zone fibre) of known length, z , preceding it (single-point technique (B.4.3.3)).39
D
Figure C.1 – Equipment set-up for phase-shift technique (C.2.2.1).45
Figure C.2 – Equipment set-up for differential pulse-delay technique (C.2.2.2) .45
Figure E.1 – Apparatus for fibre length measurement .61
Table 1 – Measurement methods .13
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60793-1-22 © IEC:2001 – 7 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
___________
OPTICAL FIBRES –
Part 1-22: Measurement methods and test procedures –
Length measurement
FOREWORD
1) The IEC (International Electrotechnical Commission) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of the 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, the IEC publishes International Standards. 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. The 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 the 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 National Committees.
3) The documents produced have the form of recommendations for international use and are published in the form
of standards, technical specifications, technical reports or guides and they are accepted by the National
Committees in that sense.
4) In order to promote international unification, IEC National Committees undertake to apply IEC International
Standards transparently to the maximum extent possible in their national and regional standards. Any
divergence between the IEC Standard and the corresponding national or regional standard shall be clearly
indicated in the latter.
4) The IEC provides no marking procedure to indicate its approval and cannot be rendered responsible for any
equipment declared to be in conformity with one of its standards.
5) Attention is drawn to the possibility that some of the elements of this International Standard may be the subject
of patent rights. The IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 60793-1-22 has been prepared by subcommittee 86A: Fibres and
cables, of IEC technical committee 86: Fibre optics.
This standard, together with the other standards in the IEC 60793-1-2X series, cancels and
replaces the first edition of IEC 60793-1-2, of which it constitutes a technical revision.
The text of this standard is based on the following documents:
FDIS Report on voting
86A/687/FDIS 86A/726/RVD
Full information on the voting for the approval of this standard can be found in the report on
voting indicated in the above table.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
Annexes A, B, C, D and E form an integral part of this standard.
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60793-1-22 © IEC:2001 – 9 –
IEC 60793-1-2X consists of the following parts, under the general title: Optical fibres:
• Part 1-20: Measurement methods and test procedures – Fibre geometry
• Part 1-21: Measurement methods and test procedures – Coating geometry
• Part 1-22: Measurement methods and test procedures – Length measurement
The committee has decided that the contents of this publication will remain unchanged
until 2003. At this date, the publication will be
• reconfirmed;
• withdrawn;
• replaced by a revised edition, or
• amended.
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60793-1-22 © IEC:2001 – 11 –
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
•
parts 1-20 to 1-29: Measurement methods and test procedures for dimensions
• parts 1-30 to 1-39: Measurement methods and test procedures for mechanical charac-
teristics
• parts 1-40 to 1-49: Measurement methods and test procedures for transmission and
optical characteristics
• parts 1-50 to 1-59: Measurement methods and test procedures for environmental charac-
teristics.
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60793-1-22 © IEC:2001 – 13 –
OPTICAL FIBRES –
Part 1-22: Measurement methods and test procedures –
Length measurement
1 Scope
This part of IEC 60793 establishes uniform requirements for measuring the length and elongation
of optical fibre (typically within cable).
The length of an optical fibre is one of the most fundamental values and shall be known for the
evaluation of transmission characteristics such as losses and bandwidths.
2 Normative references
The following referenced documents are indispensable for the application 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
IEC 60793-1-42, Optical fibres – Part 1-42: Measurement methods and test procedures –
Chromatic dispersion
IEC 60794-1-1, Optical fibre cables – Part 1-1: Generic specification – General
3 Overview of method
This standard gives five methods for measuring length, which are presented in the following
table 1.
Table 1 – Measurement methods
Characteristics Fibre category(ies) Former
Method
covered covered designation
A Delay measuring Length All A1 and all B IEC 60793-1-A6
B Backscattering Length All A1 and all B IEC 60793-1-C1C
a b
C Fibre elongation Fibre elongation A1 and B1 IEC 60793-1-A7
D Mechanical Length All IEC 60793-1-A5
E Phase shift Length All A1 and all B IEC 60793-1-A8
a
The measurement of fibre elongation, method C, is part of several measurement methods for fibres and fibre
optic cables, such as those in IEC 60794-1-1.
b
This measurement is applicable unreservedly to type B single-mode fibres. For type A1 multimode fibres, take
particular care when interpreting the results because the results of this measurement may be influenced by
interfering modal effects, for example, due to the occurrence of non-longitudinal stresses on the fibre. Application
of the measurement to A2 to A4 multimode fibres is under consideration.
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60793-1-22 © IEC:2001 – 15 –
Information common to all measurements is contained in clauses 2 to 8. Information on
specific application appears in annexes A, B, C, D, and E for methods A, B, C, D and E,
respectively.
3.1 Method A – Delay measuring
The delay measuring method applies to measurements of the fibre length by the measurement
of the propagation time of an optical pulse or a pulse train on the basis of a known value of the
group index of the fibre.
Alternatively, this method is suitable for measuring the group index of a fibre of known length.
Therefore, in practice this fibre length measurement method is calibrated against a known
length of fibre of the same type.
3.2 Method B – Backscattering
The backscattering method, which is a single-sided measurement, uses an optical time domain
reflectometer (OTDR), and measures the optical power backscattered from different points in
the fibre to the beginning of the fibre.
3.3 Method C – Fibre elongation
This measurement method describes a procedure for determining the fibre elongation. It does
not measure absolute strain, but instead measures the changes in strain from one loading
condition to another.
3.4 Method D – Mechanical length
This measurement method describes a procedure for determining the fibre length by winding a
fibre around a fixed diameter calibrated wheel that rotates. The length is determined by the
number of revolutions of the wheel.
3.5 Method E – Phase shift
The phase shift method describes a procedure for determining the fibre length. The length is
determined from the phase shift that occurs when a predetermined modulation frequency f
max
is applied.
3.6 Reference test method
The reference test method (RTM), which shall be the one used to settle disputes, varies
depending on whether the fibre is cabled or not, such as
– uncabled fibre: method D;
– length of fibre within cable: method B;
– elongation of fibre within cable: method C;
– elongation of uncabled fibre: method C.
4 Apparatus
Annexes A, B, C, D and E include layout drawings and other equipment requirements for each
of the methods A, B, C, D and E, respectively.
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60793-1-22 © IEC:2001 – 17 –
5 Sampling and specimens
See the appropriate annex A, B, C, D or E for specific requirements. General requirements
follow.
Prepare a flat end face, perpendicular to the fibre axis, at the input and output ends of each
specimen for measurements based on optical delay measurements.
6 Procedure
See the appropriate annex A, B, C, D or E for specific requirements.
7 Calculations
See the appropriate annex A, B, C, D or E for specific requirements.
8 Results
The following information shall be provided with each measurement:
– date and title of measurement;
– identification and description of specimen, including whether fibre or cable;
– specimen length, or elongation;
– measurement method used: A, B, C, D or E;
– other results, as required by the appropriate annex, A, B, C, D or E.
The following information shall be available upon request:
– description of measurement apparatus arrangement;
– type and wavelength of measurement source;
– launch conditions;
– details of computation technique;
– date of latest calibration of equipment.
See annexes A, B, C, D and E for any additional information that shall be available upon
request.
9 Specification information
The detail specification shall specify the following information:
– type of fibre (or cable) to be measured;
– failure or acceptance criteria;
– information to be reported;
– deviations to the procedure that apply.
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60793-1-22 © IEC:2001 – 19 –
Annex A
(normative)
Requirements specific to method A –
Delay measuring
A.1 General
Use this method to measure the length of optical fibre by itself, or installed in cable. If the
specimen is a fibre in a cable, determine the value of group index N under conditions
applicable to the specimen under measurement (for example, tension, temperature). This is
done by inverting equation (A.1) and the measurements on a specimen with a known length.
A.2 Principle
An optical pulse travelling through an optical fibre with length L and average group index N
experiences a travelling/delay time, Δt:
NL
Δt =
C
(A.1)
where
Δt is the time delay;
N is the average group index;
C is the velocity of light in vacuum.
If N is known, the measurement of Δt gives L. On the other hand, the measurement of Δt gives
the value of N when L is known.
A.3 Apparatus
A.3.1 Two techniques
There are two techniques for measuring the propagation time of an optical pulse:
– time measurement of the transmitted pulse (Δt measured);
– time measurement of the reflected pulse (2Δt measured).
See figures A.1 and A.2 for two different arrangements corresponding to the two techniques
applying a sampling oscilloscope.
Instead of the sampling oscilloscope, backscattering equipment, or a counter with separate
4
start/stop gate and averaging capability (for example, at least 10
counts), can be used.
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60793-1-22 © IEC:2001 – 21 –
IEC 583/01
Figure A.1 – Time measurement of the transmitted pulse
IEC 584/01
Figure A.2 – Time measurement of the reflected pulse
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60793-1-22 © IEC:2001 – 23 –
A.3.2 Optical source
A.3.2.1 Measurement with the sampling oscilloscope
An optical pulse generator shall preferably be a high-power laser diode, excited by an electrical
pulse train generator, tunable in frequency and width. Record the wavelength and the spectral
width.
A.3.2.2 Measurement with a counter or a backscattering apparatus
An optical pulse generator shall preferably be a high-power laser diode, excited by an electrical
pulse train generator, tunable in width. The time between two pulses shall be longer than the
travelling time of the transmitted pulse (Δt, with counter) or the reflected pulse (2Δt, with
backscattering equipment). Record the wavelength and the spectral width of the laser diode.
A.3.3 Optical detector
The receiver shall preferably be a high-speed avalanche photodiode. The sensitivity of the
optical detector shall be sufficient at the measuring wavelength, and its bandwidth shall be
large enough so as not to influence the shape of the pulse.
A.4 Procedure
A.4.1 Calibration
Measure the delay time of the optical source to the launching point (this is the delay time of the
measurement apparatus itself).
A.4.2 Average group index value
On a known length of mechanically measured fibre, the measurement of Δt, gives the average
value, N, of the group index of the fibre.
A.4.3 Length measurement
The length measurement is a time-domain reading on the screen of an oscilloscope (or the
reading of the averaged travelling time on the display of an electronic counter to be corrected
for the calibration value).
NOTE See figure A.3 for an illustration of an important practical improvement for achieving the accuracy of the
measurement, independent of the actual length of the fibre specimen. This uses a dual-channel approach.
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60793-1-22 © IEC:2001 – 25 –
IEC 585/01
Figure A.3a – Channel 1: emitted pulse
IEC 586/01
Figure A.3b – Channel 2: transmitted pulse
IEC 587/01
Figure A.3c – Emitted pulse after adjustment of the repetition rate in such a way that the second pulse of
channel 1 coincides with the transmitted pulse of channel 2
Figure A.3 – Principle of fibre-length measurement
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60793-1-22 © IEC:2001 – 27 –
A.5 Calculations
Obtain the fibre length from one of the following equations:
A.5.1 Transmitted-pulse technique
Δt ×c
L=
N
(A.2)
A.5.2 Reflected-pulse technique
Δt ×c
(A.3)
L=
2N
where
L is the fibre length, in m;
Δt is the transmission or reflection time, in ns;
c is the light velocity in vacuum, in m/ns;
N is the average group index.
A.6 Results
In addition to the results in clause 8, the following information shall be available upon request:
− average group index;
− delay time of the measurement apparatus (optional);
− transmission or reflection time (optional).
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60793-1-22 © IEC:2001 – 29 –
Annex B
(normative)
Requirements specific to method B –
Backscattering
B.1 General
This method uses an OTDR to measure the length of optical fibre by itself and installed in
cable.
B.2 Apparatus
This method uses an optical time-domain reflectometer (OTDR), which shall normally consist
of the following minimum list of components. See figure B.1 for a block diagram.
IEC 588/01
Figure B.1 – Block diagram of an OTDR
B.2.1 Optical transmitter
This usually includes one or more pulsed laser diode sources capable of one or more pulse
durations and pulse repetition rates. Unless otherwise specified in the detail specification, the
spectrum for each wavelength shall satisfy the following.
B.2.1.1 The central wavelength shall lie within 15 nm of the specified value; report the
difference between the central wavelength and the specified value if it is greater than 10 nm.
B.2.1.2 The root-mean-squared width (RMSW) shall not exceed 10 nm, or the full-width at
half maximum (FWHM) shall not exceed 25 nm.
B.2.1.3 If the data are to be used in a spectral attenuation model:
– the spectral width shall not exceed 15 nm (FWHM) or 6 nm (RMS) for wavelengths in the
water peak region (e.g. 1 360 nm to 1 430 nm);
– report the actual central wavelength to within 2 nm of the actual value.
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60793-1-22 © IEC:2001 – 31 –
B.2.2 Launch conditions
Provide a means for connecting the test fibre (or the optional dead-zone fibre of B.2.9) to the
instrument panel, or to a fibre pigtail from the source.
For type A fibre, optical sources may not produce launch conditions that are well controlled or
appropriate to this measurement method. Therefore, unless otherwise specified in the detail
specification, launch conditions for attenuation measurements shall be those used in cut-back
attenuation measurements (IEC 60793-1-40 method A).
B.2.3 Optical splitter
A coupler/splitter within the instrument directs the power from the transmitter into the fibre. It
also directs light returning in the fibre from the opposite direction to the receiver.
B.2.4 Optical receiver
This usually includes a photodiode detector having a bandwidth, sensitivity, linearity and
dynamic range compatible with the pulse durations used and signal levels received.
B.2.5 Pulse duration and repetition rate
The OTDR may be provided a choice of several pulse durations and repetition rates
(sometimes coupled to the distance control) to optimize the trade-off between resolution and
range. With a high amplitude reflection, it may be necessary to set the rate or range to a value
exceeding twice the distance of the reflection in order to prevent spurious ‘ghost’ images. Pulse
coding techniques may also be used.
NOTE Care should be taken when selecting the pulse duration, repetition rate and source power. For shorter
distance measurements, short pulse durations are necessary in order to provide adequate resolution. This in turn
will limit dynamic range and maximum measurable length. For long length measurements, the dynamic range can
be increased by increasing the peak optical power up to a level below which non-linear effects are insignificant.
Alternatively, pulse width can be increased, which will reduce the resolution of the measurements.
B.2.6 Signal processor
If requ
...
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