EN 61745:2017

End-face image analysis procedure for the calibration of optical fibre geometry test sets

IEC 61745:2017 describes the calibration of test sets that perform end-face image analysis, also known as "near-field" or "grey-scale" analysis. The principles, however, can be applied to test sets of a different type. The procedures outlined are performed by calibration laboratories and by the manufacturers or users of geometry test sets, for the purpose of calibrating geometry test sets and for evaluating the uncertainties in measurements made on calibrated test sets. The calibration of fibre coating or cable measurement test sets is not covered by this document. This second edition cancels and replaces the first edition, published in 1998, and constitutes a technical revision.This edition includes the following significant technical changes with respect to the previous edition: a) removal of the limitation of single mode optical fibre geometry test sets to include multimode; b) addition of a new annex as mathematical basis. Keywords: end-face image analysis, optical fibre geometry test sets

Endflächen-Bildanalyseverfahren für die Kalibrierung von Prüfeinrichtungen für die Geometrie von Lichtwellenleitern

Procédure d'analyse d'image d’extrémité pour l'étalonnage de dispositifs d'essais de géométrie des fibres optiques

IEC 61745:2017 décrit l'étalonnage de dispositifs d'essais qui effectuent une analyse d'image d’extrémité, également appelée "analyse de champ proche" ou "analyse d'échelle de gris". Les principes peuvent toutefois être appliqués à des dispositifs d'essais d'un type différent. Les procédures indiquées sont réalisées par des laboratoires d'étalonnage et par les fabricants ou les utilisateurs de dispositifs d'essais de géométrie, à des fins d'étalonnage de dispositifs d’essais de géométrie et d'évaluation des incertitudes des mesures effectuées sur des dispositifs d'essais étalonnés. Le présent document ne couvre pas l'étalonnage de dispositifs d’essais de mesure de câbles ou de revêtements de fibres. Cette deuxième édition annule et remplace la première édition parue en 1998, dont elle constitue une révision technique. Cette édition inclut les modifications techniques majeures suivantes par rapport à l'édition précédente: a) retrait de la restriction des dispositifs d'essais de géométrie aux fibres optiques unimodales pour inclure les fibres optiques multimodales; b) ajout d'une nouvelle annexe portant sur les bases mathématiques. Mots clés: analyse d’image d’extrémité, essais de géométrie des fibres optiques

Postopek analize čelne slike za umerjanje pribora za preskušanje geometrije optičnih vlaken (IEC 61745:2017)

Ta dokument opisuje kalibracijo kompletov preskusov, ki izvajajo analizo čelne slike, imenovano tudi analiza bližnjega polja (»near-field«) oziroma analiza lestvice sivih tonov (»grey-scale«). Načela se lahko uporabijo za različne vrste kompletov preskusov.
Opisane postopke izvajajo kalibracijski laboratoriji in proizvajalci ali uporabniki geometrijskih kompletov preskusov za namene kalibriranja geometrijskih kompletov preskusov in ocenjevanja negotovosti pri meritvah, izvedenih v okviru kalibriranih kompletov preskusov. Dokument ne zajema kalibracije kompletov preskusov za premaz vlaken ali meritve kablov.

General Information

• Status: Published
• Publication Date: 19-Oct-2017
• Withdrawal Date: 31-Aug-2020
• ICS: 33.180.01 - Fibre optic systems in general
• Technical Committee: CLC/SR 86 - Fibre optics
• Drafting Committee: IEC/TC 86 - IEC_TC_86
• Current Stage: 6060 - Document made available - Publishing
• Start Date: 20-Oct-2017
• Completion Date: 20-Oct-2017
• Ref Project: SIST EN 61745:2018 - End-face image analysis procedure for the calibration of optical fibre geometry test sets (IEC 61745:2017)

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 61745:2018
01-januar-2018
3RVWRSHNDQDOL]HþHOQHVOLNH]DXPHUMDQMHSULERUD]DSUHVNXãDQMHJHRPHWULMH
RSWLþQLKYODNHQ,(&

End-face image analysis procedure for the calibration of optical fibre geometry test sets

(IEC 61745:2017)
Ta slovenski standard je istoveten z: EN 61745:2017
ICS:
33.180.10 2SWLþQDYODNQDLQNDEOL Fibres and cables
SIST EN 61745:2018 en

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

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SIST EN 61745:2018
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SIST EN 61745:2018
EUROPEAN STANDARD EN 61745
NORME EUROPÉENNE
EUROPÄISCHE NORM
October 2017
ICS 33.180.01
English Version
End-face image analysis procedure for the calibration of optical
fibre geometry test sets
(IEC 61745:2017)

Procédure d'analyse d'image d'extrémité pour l'étalonnage Endflächen-Bildanalyseverfahren für die Kalibrierung von

de dispositifs d'essais de géométrie des fibres optiques Prüfeinrichtungen für die Geometrie von Lichtwellenleitern

(IEC 61745:2017) (IEC 61745:2017)

This European Standard was approved by CENELEC on 2017-09-01. 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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia,

Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden,

Switzerland, Turkey and the United Kingdom.
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung
CEN-CENELEC Management Centre: Avenue Marnix 17, B-1000 Brussels

© 2017 CENELEC All rights of exploitation in any form and by any means reserved worldwide for CENELEC Members.

Ref. No. EN 61745:2017 E
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SIST EN 61745:2018
EN 61745:2017
European foreword

The text of document 86/510/CDV, future edition 2 of IEC 61745, prepared by IEC/TC 86 "Fibre

optics" was submitted to the IEC-CENELEC parallel vote and approved by CENELEC as

EN 61745:2017.
The following dates are fixed:
latest date by which the document has to be implemented at (dop) 2018-06-01
national level by publication of an identical national
standard or by endorsement
latest date by which the national standards conflicting with (dow) 2020-09-01
the document have to be withdrawn

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.

Endorsement notice

The text of the International Standard IEC 61745:2017 was approved by CENELEC as a European

Standard without any modification.
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SIST EN 61745:2018
IEC 61745
Edition 2.0 2017-07
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
End-face image analysis procedure for the calibration of optical fibre geometry
test sets
Procédure d'analyse d'image d’extrémité pour l'étalonnage de dispositifs
d'essais de géométrie des fibres optiques
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
INTERNATIONALE
ICS 33.180.01 ISBN 978-2-8322-4614-6

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 61745:2018
– 2 – IEC 61745:2017 © IEC 2017
CONTENTS

FOREWORD ........................................................................................................................... 5

INTRODUCTION ..................................................................................................................... 7

1 Scope .............................................................................................................................. 8

2 Normative references ...................................................................................................... 8

3 Terms and definitions ...................................................................................................... 8

4 General information and preparation for calibration ....................................................... 11

4.1 Geometrical parameters of optical fibres ............................................................... 11

4.2 Description of geometry test sets .......................................................................... 11

4.3 Calibration standard requirements ........................................................................ 12

5 Calibration ..................................................................................................................... 12

5.1 General ................................................................................................................. 12

5.2 Rationale for calibration of geometry test sets ....................................................... 12

5.2.1 General ......................................................................................................... 12

5.2.2 Verification of calibration state ....................................................................... 13

5.3 Calibration procedure ............................................................................................ 14

5.3.1 General advice and organization.................................................................... 14

5.3.2 Test requirements .......................................................................................... 14

5.3.3 Calibration standard requirements ................................................................. 14

5.3.4 Determination of calibration factors................................................................ 14

5.4 Check calibration procedure .................................................................................. 16

5.5 Spatial linearity ..................................................................................................... 16

5.6 Calibration of core/cladding concentricity error measurement................................ 17

5.7 Calibration of non-circularity measurement ........................................................... 17

6 Evaluation of uncertainties ............................................................................................ 17

6.1 General ................................................................................................................. 17

6.2 Evaluation of uncertainty in test set calibration ..................................................... 18

6.2.1 General ......................................................................................................... 18

6.2.2 Uncertainty in scaling factor ........................................................................... 18

6.2.3 Uncertainty in offset correction factor ............................................................ 19

6.3 Evaluation of uncertainty in fibre measurement ..................................................... 20

6.3.1 General ......................................................................................................... 20

6.3.2 Determination of u ................................................................................ 21

Op,I,F

6.3.3 Determination of u' .................................................................................... 21

I,F

6.4 Evaluation of uncertainty in chromium mask measurement.................................... 21

6.4.1 General ......................................................................................................... 21

6.4.2 Determination of u ............................................................................... 21

Op,I,C

6.4.3 Determination of u′ .................................................................................... 21

I,C

6.5 Summary .............................................................................................................. 22

7 Documentation .............................................................................................................. 22

7.1 Records ................................................................................................................ 22

Annex A (normative) Mathematical basis for measurement uncertainty calculations ............. 23

A.1 General ................................................................................................................. 23

A.2 Type A evaluation of uncertainty ........................................................................... 23

A.3 Type B evaluation of uncertainty ........................................................................... 23

A.4 Determining the combined standard uncertainty .................................................... 24

A.5 Reporting .............................................................................................................. 25

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Annex B (informative) Derivation of calibration factors ......................................................... 26

B.1 Derivation of scaling factors .................................................................................. 26

B.2 Derivation of correction offset factor ..................................................................... 27

Annex C (informative) Examples for the determination of calibration factors ........................ 29

C.1 Example of determination of scaling factor ............................................................ 29

C.2 Example of determination of offset correction factor .............................................. 29

Annex D (informative) Calculation of uncertainties ............................................................... 30

D.1 General ................................................................................................................. 30

D.1.1 Overview ....................................................................................................... 30

D.1.2 Examples of type B evaluation of uncertainty ................................................. 30

D.2 Combining sources of uncertainty ......................................................................... 30

D.2.1 General ......................................................................................................... 30

D.2.2 Example of combining several sources of uncertainty .................................... 31

D.3 Student's t distribution .......................................................................................... 31

Annex E (informative) Worked examples for the determination of uncertainties .................... 33

E.1 General ................................................................................................................. 33

E.2 Example of determination of scaling factor uncertainty .......................................... 33

E.3 Example of determination of correction offset uncertainty ..................................... 33

E.4 Example of determination of fibre measurement uncertainty.................................. 34

E.5 Example of determination of chromium mask measurement uncertainty ................ 34

Annex F (informative) Generation of working standards ....................................................... 35

F.1 Generation of working standards ........................................................................... 35

F.1.1 General ......................................................................................................... 35

F.1.2 Measurement conditions ................................................................................ 35

F.2 Procedure for generation of working standards ..................................................... 35

F.2.1 In the case where the infant artefact is a fibre................................................ 35

F.2.2 In the case where the infant artefact is a chromium-on-glass artefact ............ 35

Annex G (informative) Estimation of uncertainty in the measurement of core/cladding

concentricity error .......................................................................................................... 36

G.1 Method of estimating uncertainty in concentricity error measurement .................... 36

G.1.1 General ......................................................................................................... 36

G.1.2 Determination of u ......................................................................................... 36

G.1.3 Determination of u .................................................................................... 36

G.1.4 Determination of CB ....................................................................................... 36

G.1.5 Determination of u ..................................................................................... 38

G.2 Correcting for concentricity bias ............................................................................ 38

Annex H (informative) Estimation of uncertainty in the measurement of non-circularity ........ 39

H.1 Method of estimating uncertainty in non-circularity measurement .......................... 39

H.2 Determination of u ................................................................................................. 39

H.3 Determination of u ............................................................................................ 39

H.4 Determination of NCB ............................................................................................ 39

H.4.1 General ......................................................................................................... 39

H.4.2 Method A: uncalibrated artefact ..................................................................... 40

H.4.3 Method B: calibrated artefact ......................................................................... 40

H.5 Determination of u ......................................................................................... 40

NCB

Bibliography .......................................................................................................................... 41

Figure 1 – Example of a calibration chain and the accumulation of uncertainties ................... 13

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Figure B.1 – Representation of a grid calibration mask ......................................................... 26

Figure B.2 – Representation of an annulus calibration mask ................................................. 27

Figure B.3 – Derivation of correction offset ........................................................................... 28

Table D.1 – Values of t for specified confidence level ........................................................... 32

Table G.1 – Measured values for angular positions ............................................................... 37

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SIST EN 61745:2018
IEC 61745:2017 © IEC 2017 – 5 –
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
END-FACE IMAGE ANALYSIS PROCEDURE FOR THE CALIBRATION
OF OPTICAL FIBRE GEOMETRY TEST SETS
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

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

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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

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services carried out by independent certification bodies.

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

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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.

International Standard IEC 61745 has been prepared by IEC technical committee 86: Fibre

optics.

This second edition cancels and replaces the first edition, published in 1998, and constitutes

a technical revision.

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

edition:

a) removal of the limitation of single mode optical fibre geometry test sets to include

multimode;
b) addition of a new annex as mathematical basis.
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SIST EN 61745:2018
– 6 – IEC 61745:2017 © IEC 2017
The text of this International Standard is based on the following documents:
CDV Report on voting
86/510/CDV 86/516/RVC

Full information on the voting for the approval of this International Standard can be found in

the report on voting indicated in the above table.

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

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

stability date indicated on the IEC website under "http://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.
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SIST EN 61745:2018
IEC 61745:2017 © IEC 2017 – 7 –
INTRODUCTION

In the research and production environments, there exists a range of test methods for

characterizing the geometry of optical fibres. Furthermore, each test method may determine

one or more of the many parameters required for complete geometrical characterization.

IEC 61745 describes the calibration of test sets that perform end-face image analysis, also

known as "near-field" or "grey-scale" analysis. The principles, however, may be applied to test

sets of a different type.
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SIST EN 61745:2018
– 8 – IEC 61745:2017 © IEC 2017
END-FACE IMAGE ANALYSIS PROCEDURE FOR THE CALIBRATION
OF OPTICAL FIBRE GEOMETRY TEST SETS
1 Scope

This document describes the calibration of test sets that perform end-face image analysis,

also known as "near-field" or "grey-scale" analysis. The principles, however, can be applied to

test sets of a different type.

The procedures outlined are performed by calibration laboratories and by the manufacturers

or users of geometry test sets, for the purpose of calibrating geometry test sets and for

evaluating the uncertainties in measurements made on calibrated test sets. The calibration of

fibre coating or cable measurement test sets is not covered by this document.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purpose of this International Standard, the following definitions apply.

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

addresses:
• IEC Electropedia: available at http://www.electropedia.org/
• ISO Online browsing platform: available at http://www.iso.org/obp
3.1
accredited calibration laboratory

calibration laboratory authorized by an appropriate national organization to issue calibration

certificates that demonstrates traceability to national standards
3.2
artefact
object that is measured on or used to calibrate a geometry test set

EXAMPLE An optical fibre and a chromium-on-glass pattern are examples of artefacts.

3.3
calibration

set of operations that establish, under specified conditions, the relationship between the

values of quantities indicated by a measuring instrument and the corresponding values

realized by standards

Note 1 to entry: The results of a calibration permit either the assignment of measurand values to the indications

or the determination of corrections with respect to the indications.

Note 2 to entry: A calibration may also determine other metrological properties such as the effects of influence

quantities.

Note 3 to entry: The result of a calibration may be recorded in a document, called a "calibration certificate" or a

"calibration report".
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SIST EN 61745:2018
IEC 61745:2017 © IEC 2017 – 9 –
3.4
calibration chain

chain of transfers from a national standard to the geometry test set through intermediate or

working standards
Note 1 to entry: See U = k × u.
3.5
calibration checking

establishing that a geometry test set that has been previously calibrated but has reached its

calibration due date remains within specified uncertainty limits

Note 1 to entry: If the geometry test set has drifted outside these limits, then re-calibration is required. Otherwise,

the re-checking period can be extended for a stated period.
Note 2 to entry: The test set may be checked using a working standard.
3.6
calibration standard

artefact that is calibrated against a reference standard and is used to calibrate test sets

Note 1 to entry: The artefact may be a fibre or a chromium-on-glass pattern.
Note 2 to entry: Proper use of a calibration standard ensures traceability.

Note 3 to entry: The term includes the reference standard, the transfer standard and the working standard(s), in

descending order of metrological uncertainty.
3.7
combined standard uncertainty
combination of a number of individual standard uncertainties
Note 1 to entry: The term "accuracy" should be avoided in this context.

Note 2 to entry: In calibration reports and technical data sheets, the combined standard uncertainty in the

geometry test set measurement is reported as an overall expanded uncertainty with the applicable confidence

level, for example 95,5% or 99,7 %.
3.8
confidence level

estimation of the probability that the true value of a measured parameter lies within a given

range (expanded uncertainty)
3.9
correction offset

number that is added to or subtracted from the measurement result of a test set to correct for

a known physical effect
3.10
coverage factor

factor used to calculate the expanded uncertainty, U, from the standard uncertainty, u

3.11
expanded uncertainty

range of values within which the measurement parameter, at the stated confidence level, can

be expected to lie

Note 1 to entry: It is equal to the coverage factor, k, times the combined standard uncertainty u

U= k× u (1)
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SIST EN 61745:2018
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Note 2 to entry: When the distribution of uncertainties is assumed to be normal and a large number of

measurements are made, then confidence levels of 68,3 %, 95,5 % and 99,7 % correspond to k values of 1, 2 and

3 respectively.
3.12
geometry test set
instrument used to measure the geometrical parameters of an optical fibre

Note 1 to entry: The parameters measured will depend on the type of geometry test set.

3.13
infant fibre
fibre whose geometry is to be measured on a calibrated geometry test set
3.14
instrument state

description of the measurement conditions of the geometry test set during calibration and

measurement

Note 1 to entry: The measurements conditions are for instance form-fits used, data filtering schemes employed

and other important information concerning the test set such as warm-up time and date of calibration.

3.15
national standard

standard recognized by a national decision to serve, in a country, as the basis for assigning

values to other standards of the quantity concerned

[SOURCE: ISO/IEC Guide 99:2007, 5.3, modified – The first preferred term "national

measurement standard" has been deleted, and the definition has been rephrased.]
3.16
national standards laboratory
laboratory which maintains the national standard
3.17
operating range

range of conditions under which the geometry test set is designed to perform within the stated

expanded uncertainty

Note 1 to entry: Such conditions include the diameter of the fibre being measured and environmental conditions,

such as temperature.
3.18
reference standard

artefact measured at a calibration laboratory, with the measurement traceable to national

standards
3.19
scaling factor

ratio of the known standard values for a calibration standard to the values indicated by the

geometry test set when no correction offsets are applied
3.20
standard uncertainty
uncertainty of a measurement result expressed as a standard deviation
Note 1 to entry: For further information, see Annex A and ISO/IEC Guide 98-3.
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IEC 61745:2017 © IEC 2017 – 11 –
3.21
traceability

ability to demonstrate, for a measurement result or a geometry test set, a calibration chain

originating from a national standard

Note 1 to entry: Geometry test sets calibrated by the procedures in this document are traceable. Direct

traceability of the measurement results either to a national standards laboratory or to an accredited calibration

laboratory need to be demonstrated. Such traceability includes the calibration schedules of all artefacts in the

calibration chain and detailed calculations of all (cumulative) transfer uncertainties in the calibration chain.

Note 2 to entry: The use of a working standard alone to compare or monitor geometry test set calibration cannot

establish or re-establish traceability, but can only extend the duration of the traceability certification if no change is

found.
3.22
transfer standard

standard that is calibrated against a reference standard and is used for calibrating geometry

test sets
3.23
transfer uncertainty

estimate characterizing the uncertainty of a measurement caused by uncertainties in the

transfer process, at the given confidence level (such as changes in environmental conditions)

Note 1 to entry: These uncertainties may arise from the calibration standards used as well as from the geometry

test set.
3.24
working standard
standard that is used on a
...