SIST EN 62129-2:2011

Calibration of wavelength/optical frequency measurement insturments - Part 2: Michelson interferometer single wavelength meters (IEC 62129-2:2011)

This part of IEC 62129 is applicable to instruments measuring the vacuum wavelength or optical frequency emitted from sources that are typical for the fibre-optic communications industry. These sources include Distributed Feedback (DFB) laser diodes, External Cavity lasers and single longitudinal mode fibre-type sources. It is assumed that the optical radiation will be coupled to the wavelength meter by a single-mode optical fibre. The standard describes the calibration of wavelength meters to be performed by calibration laboratories or by wavelength meter manufacturers. This standard is part of the IEC 62129 series on the calibration of wavelength/optical frequency measurement instruments. Refer to IEC 62129 for the calibration of optical spectrum analyzers.

Kalibrierung von Messgeräten für die Wellenlänge/optische Frequenz - Teil 2: Michelson-Interferometer-Einzelwellenlängen-Messgerät (IEC 62129-2:2011)

Etalonnage des appareils de mesure de longueur d'onde/appareil de mesure de la fréquence optique - Partie 2: Appareils de mesure de longueur d'onde unique à interféromètre de Michelson (CEI 62129-2:2011)

La CEI 62129-2:2011 est applicable aux instruments mesurant la longueur d'onde ou la fréquence optique dans le vide émise par des sources types de l'industrie des communications par fibres optiques. Ces sources comportent des diodes laser DFB (à rétroaction répartie, Distributed Feedback), des lasers à cavité externe et des sources du type à fibres unimodales longitudinales. La présente norme fait partie de la série CEI 62129 relative à l'étalonnage des appareils de mesure de longueur d'onde/appareils de mesure de fréquence optique. Se référer à la CEI 62129 pour l'étalonnage des analyseurs de spectre optique.

Kalibriranje valovno-dolžinskih/optično-frekvenčnih merilnih instrumentov - 2. del: Merilniki ene valovne dolžine z Michelsonovim interferometrom (IEC 62129-2:2011)

Ta del IEC 62129 velja za instrumente, ki merijo vakuumsko valovno dolžino ali optično frekvenco, ki jo oddajajo viri, značilni za industrijo komunikacije z optičnimi vlakni. Ti viri vključujejo laserske diode s porazdeljenim povratnim sklopom (DFB), laserje z zunanjo votlino in vire z enorodnim vzdolžnim vlaknom. Domneva se, da se optično sevanje sklopi z merilnikom valovnih dolžin z enorodnim optičnim vlaknom. Standard opisuje kalibracijo merilnikov valovnih dolžin, ki se izvaja v kalibracijskih laboratorijih ali pri proizvajalcih merilnikov valovnih dolžin. Ta standard je del serije IEC 62129 o kalibraciji valovno-dolžinskih/optično-frekvenčnih merilnih instrumentov. Za kalibracijo analizatorjev optičnega spektra glej IEC 62129.

General Information

• Status: Published
• Publication Date: 24-Jul-2011
• ICS: 33.180.01 - Fibre optic systems in general
• Technical Committee: MOC - Mobile Communications
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 13-Jul-2011
• Due Date: 17-Sep-2011
• Completion Date: 25-Jul-2011
• Ref Project: EN 62129-2:2011 - Calibration of wavelength/optical frequency measurement instruments - Part 2: Michelson interferometer single wavelength meters

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN 62129-2:2011
01-september-2011
.DOLEULUDQMHYDORYQRGROåLQVNLKRSWLþQRIUHNYHQþQLKPHULOQLKLQVWUXPHQWRYGHO
0HULOQLNLHQHYDORYQHGROåLQH]0LFKHOVRQRYLPLQWHUIHURPHWURP,(&
Calibration of wavelength/optical frequency measurement insturments - Part 2:
Michelson interferometer single wavelength meters (IEC 62129-2:2011)
Kalibrierung von Messgeräten für die Wellenlänge/optische Frequenz - Teil 2: Michelson-
Interferometer-Einzelwellenlängen-Messgerät (IEC 62129-2:2011)
Etalonnage des appareils de mesure de longueur d'onde/appareil de mesure de la
fréquence optique - Partie 2: Appareils de mesure de longueur d'onde unique à
interféromètre de Michelson (CEI 62129-2:2011)
Ta slovenski standard je istoveten z: EN 62129-2:2011
ICS:
33.180.01 6LVWHPL]RSWLþQLPLYODNQLQD Fibre optic systems in
VSORãQR general
SIST EN 62129-2:2011 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN 62129-2:2011

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SIST EN 62129-2:2011

EUROPEAN STANDARD
EN 62129-2

NORME EUROPÉENNE
July 2011
EUROPÄISCHE NORM

ICS 33.180.30


English version


Calibration of wavelength/optical frequency measurement instruments -
Part 2: Michelson interferometer single wavelength meters
(IEC 62129-2:2011)


Etalonnage des appareils de mesure de Kalibrierung von Messgeräten für die
longueur d'onde/appareil de mesure de la Wellenlänge/optische Frequenz -
fréquence optique - Teil 2: Michelson-Interferometer-
Partie 2: Appareils de mesure de longueur Einzelwellenlängen-Messgeräte
d'onde unique à interféromètre de (IEC 62129-2:2011)
Michelson
(CEI 62129-2:2011)





This European Standard was approved by CENELEC on 2011-06-30. 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, Bulgaria, Croatia, Cyprus,
the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy,
Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Portugal, Romania, Slovakia, Slovenia,
Spain, Sweden, Switzerland and the United Kingdom.

CENELEC
European Committee for Electrotechnical Standardization
Comité Européen de Normalisation Electrotechnique
Europäisches Komitee für Elektrotechnische Normung

Management Centre: Avenue Marnix 17, B - 1000 Brussels


© 2011 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members.
Ref. No. EN 62129-2:2011 E

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SIST EN 62129-2:2011
EN 62129-2:2011 - 2 -
Foreword
The text of document 86/395/FDIS, future edition 1 of IEC 62129-2, prepared by IEC TC 86, Fibre optics,
was submitted to the IEC-CENELEC parallel vote and was approved by CENELEC as EN 62129-2 on
2011-06-30.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent
rights.
The following dates were fixed:
– latest date by which the EN has to be implemented
at national level by publication of an identical
(dop) 2012-03-30
national standard or by endorsement
– latest date by which the national standards conflicting
(dow) 2014-06-30
with the EN have to be withdrawn
Annex ZA has been added by CENELEC.
__________
Endorsement notice
The text of the International Standard IEC 62129-2:2011 was approved by CENELEC as a European
Standard without any modification.
In the official version, for Bibliography, the following notes have to be added for the standards indicated:
IEC 60793-1-1 NOTE  Harmonized as EN 60793-1-1.
IEC 60825-1 NOTE  Harmonized as EN 60825-1.
IEC 60825-2 NOTE  Harmonized as EN 60825-2.
__________

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SIST EN 62129-2:2011
- 3 - EN 62129-2:2011
Annex ZA
(normative)

Normative references to international publications
with their corresponding European publications

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.

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

IEC 60050-300 2001 International Electrotechnical Vocabulary - - -
Electrical and electronic measurements and
measuring instruments -
Part 311: General terms relating to
measurements -
Part 312: General terms relating to electrical
measurements -
Part 313: Types of electrical measuring
instruments -
Part 314: Specific terms according to the type
of instrument


IEC 61315 2005 Calibration of fibre-optic power meters EN 61315 2006


IEC/TR 61931 1998 Fibre optic - Terminology - -


ISO/IEC 17025 2005 General requirements for the competence of EN ISO/IEC 17025 2005
testing and calibration laboratories


ISO/IEC Guide 99 2007 International vocabulary of metrology - Basic - -
and general concepts and associated terms
(VIM)


ISO/IEC Guide 98-3 2008 Uncertainty of measurement - - -
Part 3: Guide to the expression of uncertainty
in measurement (GUM:1995)

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SIST EN 62129-2:2011

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SIST EN 62129-2:2011

IEC 62129-2
®

Edition 1.0 2011-05
INTERNATIONAL
STANDARD
NORME
INTERNATIONALE
colour
inside


Calibration of wavelength/optical frequency measurement instruments –
Part 2: Michelson interferometer single wavelength meters

Étalonnage des appareils de mesure de longueur d’onde/appareil de mesure
de la fréquence optique –
Partie 2: Appareils de mesure de longueur d'onde unique à interféromètre de
Michelson

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
COMMISSION
ELECTROTECHNIQUE
PRICE CODE
INTERNATIONALE
CODE PRIX X
ICS 33.180.30 ISBN 978-2-88912-523-4

® Registered trademark of the International Electrotechnical Commission
Marque déposée de la Commission Electrotechnique Internationale

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SIST EN 62129-2:2011
– 2 – 62129-2  IEC:2011
CONTENTS
FOREWORD . 4
INTRODUCTION . 6
1 Scope . 7
2 Normative references. 7
3 Terms and definitions . 7
4 Preparation for calibration . 11
4.1 Organization . 11
4.2 Traceability . 11
4.3 Advice for measurements and calibrations . 11
4.4 Recommendations to customers . 12
5 Single wavelength calibration . 12
5.1 General . 12
5.2 Establishing calibration conditions. 12
5.3 Calibration procedure . 13
5.3.1 General . 13
5.3.2 Measurement configuration . 13
5.3.3 Detailed procedure. 15
5.3.4 Stability test (if necessary) . 15
5.3.5 "On/Off repeatability" measurement (optional if a specification is
available) . 16
5.3.6 Wavelength dependence measurement (optional) . 18
5.3.7 Connector repeatability measurement (optional) . 19
5.4 Calibration uncertainty . 20
5.5 Reporting the results . 21
6 Absolute power calibration . 21
Annex A (normative) Mathematical basis . 22
Annex B (informative) Rejection of outliers . 25
Annex C (informative) Example of a single wavelength calibration . 27
Annex D (informative) ITU wavelength bands . 30
Annex E (informative) Atomic and molecular reference transitions . 31
Annex F (informative) Reference locked laser example . 42
Annex G (informative) Balance between accuracy and calibration time. 44
Bibliography . 46

Figure 1 – Example of a traceability chain. 10
Figure 2 – Wavelength meter measurement using a lock quality monitor signal . 14
Figure 3 – Wavelength meter measurement using a reference wavelength meter . 14
Figure F.1 – Typical measurement arrangement to lock laser to gas absorption line . 43

Table 1 – Typical parameters to calculate the "On/Off repeatability" measurement
duration . 17
Table B.1 – Critical values Z as a function of sample size N . 26
c
Table C.1 – Type A uncertainty contributions for a stability measurement . 27
Table C.2 – Uncertainty contributions for a "On/Off repeatability" measurement . 28

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SIST EN 62129-2:2011
62129-2  IEC:2011 – 3 –
Table C.3 – Uncertainty budget for wavelength dependence . 28
Table C.4 – Uncertainty budget for the wavelength meter calibration . 29
Table D.1 – The ITU-T bands in different units . 30
Table E.1 – Helium-neon laser lines . 32
12
Table E.2 – Centre vacuum wavelengths for Acetylene C H . 33
2 2
Table E.3 – Frequency and vacuum wavelength values for the v + v and v + v + v +
1 3 1 2 4
13
v bands of C H . 35
5 2 2
13
Table E.4 – List of H CN transitions . 38
12 16
Table E.5 – List of C O transitions. 40
Table E.6 – Excited state optogalvanic transitions . 41
Table G.1 – Summary of choices . 45

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SIST EN 62129-2:2011
– 4 – 62129-2  IEC:2011
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________

CALIBRATION OF WAVELENGTH/OPTICAL FREQUENCY
MEASUREMENT INSTRUMENTS –

Part 2: Michelson interferometer single wavelength meters


FOREWORD
1) The International Electrotechnical Commission (IEC) is a worldwide organization for standardization comprising
all national electrotechnical committees (IEC National Committees). The object of IEC is to promote
international co-operation on all questions concerning standardization in the electrical and electronic fields. To
this end and in addition to other activities, IEC publishes International Standards, Technical Specifications,
Technical Reports, Publicly Available Specifications (PAS) and Guides (hereafter referred to as “IEC
Publication(s)”). Their preparation is entrusted to technical committees; any IEC National Committee interested
in the subject dealt with may participate in this preparatory work. International, governmental and non-
governmental organizations liaising with the IEC also participate in this preparation. IEC collaborates closely
with the International Organization for Standardization (ISO) in accordance with conditions determined by
agreement between the two organizations.
2) The formal decisions or agreements of IEC on technical matters express, as nearly as possible, an international
consensus of opinion on the relevant subjects since each technical committee has representation from all
interested IEC National Committees.
3) IEC Publications have the form of recommendations for international use and are accepted by IEC National
Committees in that sense. While all reasonable efforts are made to ensure that the technical content of IEC
Publications is accurate, IEC cannot be held responsible for the way in which they are used or for any
misinterpretation by any end user.
4) In order to promote international uniformity, IEC National Committees undertake to apply IEC Publications
transparently to the maximum extent possible in their national and regional publications. Any divergence
between any IEC Publication and the corresponding national or regional publication shall be clearly indicated in
the latter.
5) IEC itself does not provide any attestation of conformity. Independent certification bodies provide conformity
assessment services and, in some areas, access to IEC marks of conformity. IEC is not responsible for any
services carried out by independent certification bodies.
6) All users should ensure that they have the latest edition of this publication.
7) No liability shall attach to IEC or its directors, employees, servants or agents including individual experts and
members of its technical committees and IEC National Committees for any personal injury, property damage or
other damage of any nature whatsoever, whether direct or indirect, or for costs (including legal fees) and
expenses arising out of the publication, use of, or reliance upon, this IEC Publication or any other IEC
Publications.
8) Attention is drawn to the Normative references cited in this publication. Use of the referenced publications is
indispensable for the correct application of this publication.
9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of
patent rights. IEC shall not be held responsible for identifying any or all such patent rights.
International Standard IEC 62129-2 has been prepared by IEC technical committee 86: Fibre
optics.
The text of this standard is based on the following documents:
FDIS Report on voting
86/395/FDIS 86/399/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.

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SIST EN 62129-2:2011
62129-2  IEC:2011 – 5 –
The list of all parts in the IEC 62129 series, published under the general title, Calibration of
wavelength/optical frequency – Measurement instruments, can be found on the IEC website.
The committee has decided that the contents of this publication will remain unchanged until the
stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data related to
the specific publication. At this date, the publication will be
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct understanding
of its contents. Users should therefore print this document using a colour printer.

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SIST EN 62129-2:2011
– 6 – 62129-2  IEC:2011
INTRODUCTION
Wavelength meters, often based on the Michelson interferometer, are designed to measure the
wavelength of an optical source as accurately as possible. Although the wavelength meters
contain an internal absolute reference, typically a Helium-Neon laser, calibration is required to
achieve the highest accuracies. The instrument is typically used to measure wavelengths other
than that of the internal reference. Corrections are made within the instrument for the refractive
index of the surrounding air. A precise description of the calibration conditions must therefore
be an integral part of the calibration.
This international standard defines all of the steps involved in the calibration process:
establishing the calibration conditions, carrying out the calibration, calculating the uncertainty,
and reporting the uncertainty, the calibration conditions and the traceability.
The calibration procedure describes how to determine the ratio between the value of the input
reference wavelength (or the optical frequency) and the wavelength meter's result. This ratio is
called correction factor. The measurement uncertainty of the correction factor is combined
following Annex A from uncertainty contributions from the reference meter, the test meter, the
setup and the procedure.
The calculations go through detailed characterization of individual uncertainties. It is important
to know that:
a) estimations of the individual uncertainties are acceptable;
b) a detailed uncertainty analysis is only necessary once for each wavelength meter type
under test, and that all subsequent calibrations can be based on this one-time analysis;
c) some of the individual uncertainties can simply be considered to be part of a checklist, with
an actual value which can be neglected.
A number of optical frequency references can be used to provide a traceable optical frequency.
These are based on absorption by gas molecules under low pressure and using excited-state
opto-galvanic transitions in atoms. Annex E lists the lines.

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SIST EN 62129-2:2011
62129-2  IEC:2011 – 7 –
CALIBRATION OF WAVELENGTH/OPTICAL FREQUENCY
MEASUREMENT INSTRUMENTS –

Part 2: Michelson interferometer single wavelength meters



1 Scope
This part of IEC 62129 is applicable to instruments measuring the vacuum wavelength or
optical frequency emitted from sources that are typical for the fibre-optic communications
industry. These sources include Distributed Feedback (DFB) laser diodes, External Cavity
lasers and single longitudinal mode fibre-type sources. It is assumed that the optical radiation
will be coupled to the wavelength meter by a single-mode optical fibre. The standard describes
the calibration of wavelength meters to be performed by calibration laboratories or by
wavelength meter manufacturers. This standard is part of the IEC 62129 series on the
calibration of wavelength/optical frequency measurement instruments. Refer to IEC 62129 for
the calibration of optical spectrum analyzers.
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 60050-300:2001, International Electrotechnical Vocabulary – Electrical and electronic
measurements and measuring instruments – Part 311: General terms relating to measurements
– Part 312: General terms relating to electrical instruments – Part 313: Types of electrical
measuring instruments – Part 314: Specific terms according to the type of instrument
IEC 61315 :2005, Calibration of fibre-optic power meters
IEC/TR 61931:1998, Fibre optic – Terminology
ISO/IEC 17025:2005, General requirements for the competence of testing and calibration
laboratories
ISO/IEC Guide 99:2007, International vocabulary of metrology – Basic and general concepts
and associated terms (VIM)
ISO/IEC Guide 98-3:2008, Uncertainty of measurement – Part 3: Guide to the expression of
uncertainty in measurement (GUM:1995)
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
accredited calibration laboratory
calibration laboratory authorized by the appropriate national organization to issue calibration
certificates with a minimum specified uncertainty, which demonstrate traceability to national
standards

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SIST EN 62129-2:2011
– 8 – 62129-2  IEC:2011
3.2
adjustment
set of operations carried out on an instrument in order that it provides given indications
corresponding to given values of the measurand
[IEC 60050-300:2001 (311-03-16); see also ISO/IEC Guide 99:2007, 3.11, modified]
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
[ISO/IEC Guide 99:2007, 2.39, modified]
NOTE 1 The result of a calibration permits either the assignment of values of measurands to the indications or the
determination of corrections with respect to indications.
NOTE 2 A calibration may also determine other metrological properties such as the effect of influence quantities.
NOTE 3 The result of a calibration may be recorded in a document, sometimes called a calibration certificate or a
calibration report.
3.4
calibration conditions
conditions of measurements in which the calibration is performed
3.5
correction factor
CF
numerical factor by which the uncorrected result of a measurement is multiplied to compensate
for systematic error
[ISO/IEC Guide 99:2007, 2.53, modified]
3.6
detector
the element of the wavelength meter that transduces the radiant optical power into a
measurable, usually electrical quantity
[IEC/TR 61931 and ISO/IEC Guide 99:2007, 3.9, modified]
3.7
deviation
value minus its reference value
NOTE In this standard, the deviation is the difference between the indication of the test meter and the indication of
the reference meter when excited under the same conditions.
3.8
excitation (fibre-)
description of the distribution of optical power between the modes in the fibre
NOTE Single mode fibres are generally assumed to be excited by only one mode (the fundamental mode).
3.9
instrument state
complete description of the state of the meter during the calibration

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SIST EN 62129-2:2011
62129-2  IEC:2011 – 9 –
3.10
measuring range
set of values of measurands for which the error of a measuring instrument is intended to lie
within specified limits
[ISO/IEC Guide 99:2007, 4.7, modified]
NOTE In this standard, the measuring range is the range of radiant power (part of the operating range), for which
the uncertainty at operating conditions is specified. The term "dynamic range" should be avoided in this context.
3.11
national (measurement) 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
[ISO/IEC Guide 99:2007, 5.3, modified]
3.12
national standards laboratory
laboratory which maintains the national standard
3.13
natural standard
atomic or molecular transition that can be used to realise a reference standard
3.14
operating conditions
appropriate set of specified ranges of values of influence quantities usually wider than the
reference conditions for which the uncertainties of a measuring instrument are specified
[ISO/IEC Guide 99:2007, 4.9, modified]
NOTE The operating conditions and uncertainty at operating conditions are usually specified by manufacturer for
the convenience of the user.
3.15
operating range
specified range of values of one of a set of operating conditions
3.16
optical input port
physical input of the wavelength meter (or standard) to which the radiant power is to be applied
or to which the optical fibre end is to be connected. An optical path (path of rays with or without
optical elements like lenses, diaphragms, light guides, etc.) is assumed to connect the optical
input port with the detector
3.17
reference conditions
conditions of use prescribed for testing the performance of a measuring instrument or for
intercomparison of results of measurements
[ISO/IEC Guide 99:2007, 4.11, modified]
NOTE The reference conditions generally include reference values or reference ranges for the influence quantities
affecting the measuring instrument.
3.18
reference wavelength meter
standard which is used as the reference to calibrate a test wavelength meter

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SIST EN 62129-2:2011
– 10 – 62129-2  IEC:2011
3.19
reference source
laser stabilized by reference to an atomic or molecular transition, or a stabilized frequency
comb, of known frequency/wavelength
3.20
reference standard
standard, generally having the highest metrological quality available at a given location or in a
given organization, from which measurements made there are derived
[ISO/IEC Guide 99:2007, 5.6, modified]
3.21
test meter
wavelength meter (or standard) to be calibrated by comparison with the reference wavelength
meter or the reference standard
3.22
traceability
property of the result of a measurement or the value of a standard whereby it can be related to
stated references, usually national or international standards, through an unbroken chain of
comparisons all having stated uncertainties
[ISO/IEC Guide 99:2007, 2.41, modified]
3.23
traceability chain
unbroken chain of comparison (see Figure 1)
[ISO/IEC Guide 99:2007, 2.41 and 2.42, modified]

National
standard

National standards laboratory

Working
standard

Accredited calibration laboratory
Transfer

standard
Calibration laboratory of company

Working
standard


Test Meter
IEC  1144/11

Figure 1 – Example of a traceability chain
3.24
wavelength meter (Michelson interferometer single-)
instrument, based on a Michelson interferometer, capable of measuring the wavelength of one
source

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SIST EN 62129-2:2011
62129-2  IEC:2011 – 11 –
NOTE Certain instrument designs can also measure the input power but with a larger uncertainty than most power
meters.
3.25
working standard
standard that is used routinely to calibrate measuring instruments
[ISO/IEC Guide 99:2007, 5.7, modified]
NOTE A working standard is usually calibrated against a reference standard.
4 Preparation for calibration
4.1 Organization
The calibration laboratory should satisfy requirements of ISO/IEC 17025.
There shall be a documented measurement procedure for each type of calibration performed,
giving step-by-step operating instructions and equipment to be used.
4.2 Traceability
The requirements of ISO/IEC 17025 should be met.
All standards used in the calibration process shall be calibrated according to a documented
programme with traceability to national standards laboratories or to accredited calibration
laboratories. It is advisable to maintain more than one standard on each hierarchical level, so
that the performance of the standard can be veri
...