SIST EN ISO 11554:2025

SLOVENSKI STANDARD
01-september-2025
Nadomešča:
SIST EN ISO 11554:2017
Optika in fotonska tehnologija - Laserji in laserska oprema - Preskusne metode za
sevalno moč, sevalno energijo in časovne karakteristike laserkih žarkov (ISO
11554:2025)
Optics and photonics - Lasers and laser-related equipment - Test methods for laser
beam radiant power, radiant energy and temporal characteristics (ISO 11554:2025)
Optik und Photonik - Laser und Laseranlagen - Prüfverfahren für Leistung, Energie und
Kenngrößen des Zeitverhaltens von Laserstrahlen (ISO 11554:2025)
Optique et photonique - Lasers et équipements associés aux lasers - Méthodes d'essai
de la puissance rayonnante, de l'énergie rayonnante et des caractéristiques temporelles
des faisceaux lasers (ISO 11554:2025)
Ta slovenski standard je istoveten z: EN ISO 11554:2025
ICS:
31.260 Optoelektronika, laserska Optoelectronics. Laser
oprema equipment
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 11554
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2025
EUROPÄISCHE NORM
ICS 31.260 Supersedes EN ISO 11554:2017
English Version
Optics and photonics - Lasers and laser-related equipment
- Test methods for laser beam radiant power, radiant
energy and temporal characteristics (ISO 11554:2025)
Optique et photonique - Lasers et équipements Optik und Photonik - Laser und Laseranlagen -
associés aux lasers - Méthodes d'essai de la puissance Prüfverfahren für Leistung, Energie und Kenngrößen
rayonnante, de l'énergie rayonnante et des des Zeitverhaltens von Laserstrahlen (ISO
caractéristiques temporelles des faisceaux lasers (ISO 11554:2025)
11554:2025)
This European Standard was approved by CEN on 13 November 2023.

CEN 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 CEN
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 CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

CEN members are the national standards bodies of Austria, Belgium, Bulgaria, Croatia, Cyprus, Czech Republic, Denmark, Estonia,
Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway,
Poland, Portugal, Republic of North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and
United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 11554:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 11554:2025) has been prepared by Technical Committee ISO/TC 172 "Optics
and photonics" in collaboration with Technical Committee CEN/TC 123 “Lasers and photonics” the
secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by December 2025, and conflicting national standards
shall be withdrawn at the latest by December 2025.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 11554:2017.
This document has been prepared under a standardization request addressed to CEN by the European
Commission. The Standing Committee of the EFTA States subsequently approves these requests for its
Member States.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 11554:2025 has been approved by CEN as EN ISO 11554:2025 without any modification.

International
Standard
ISO 11554
Fifth edition
Optics and photonics — Lasers and
2025-06
laser-related equipment — Test
methods for laser beam radiant
power, radiant energy and temporal
characteristics
Optique et photonique — Lasers et équipements associés aux
lasers — Méthodes d'essai de la puissance rayonnante, de
l'énergie rayonnante et des caractéristiques temporelles des
faisceaux lasers
Reference number
ISO 11554:2025(en) © ISO 2025
ISO 11554:2025(en)
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 11554:2025(en)
Contents Page
Foreword .iv
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and units of measurement . 2
5 Measurement principles . 3
6 Measurement configuration, test equipment and auxiliary devices . 3
6.1 Preparation .3
6.1.1 Sources with small divergence angles .3
6.1.2 Sources with large divergence angles .3
6.1.3 RIN measurement .4
6.1.4 Measurement of small signal cut off frequency .5
6.2 Control of environmental impacts .6
6.3 Detectors.6
6.4 Beam-forming optics .7
6.5 Optical attenuators .7
7 Measurements . 7
7.1 General .7
7.2 Radiant power of cw lasers .7
7.3 Radiant power stability of cw lasers.8
7.4 Radiant pulse energy of pulsed lasers .8
7.5 Radiant energy stability of pulsed lasers .8
7.6 Temporal radiant pulse shape, radiant pulse duration, rise time, fall time and peak
radiant power .8
7.7 Radiant pulse duration stability .8
7.8 Radiant pulse repetition rate .8
7.9 Relative intensity noise, RIN .9
7.10 Small signal cut-off frequency .9
8 Evaluation . 9
8.1 General .9
8.2 Radiant power of cw lasers .10
8.3 Radiant power stability of cw lasers.10
8.4 Radiant pulse energy of pulsed lasers .10
8.5 Radiant energy stability of pulsed lasers .11
8.6 Temporal radiant pulse shape, radiant pulse duration, rise time, fall time and peak
radiant power .11
8.7 Radiant pulse duration stability . 13
8.8 Radiant pulse repetition rate . 13
8.9 Relative intensity noise, RIN . 13
8.10 Small signal cut-off frequency . 13
9 Test report .13
Annex A (informative) Relative intensity noise (RIN) . 17
Bibliography . 19

iii
ISO 11554:2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO 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, ISO 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
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee SC 9,
Laser and electro-optical systems, in collaboration with the European Committee for Standardization (CEN)
Technical Committee CEN/TC 123, Lasers and photonics, in accordance with the Agreement on technical
cooperation between ISO and CEN (Vienna Agreement).
This fifth edition cancels and replaces the fourth edition (ISO 11554:2017) which has been technically
revised.
The main changes are as follows:
a) Whole document: The term “power" and “energy” that mean optical power and optical energy have been
replaced by “radiant power” and “radiant energy”, respectively, and the word “spectral density” has been
replaced by “spectral” in order to align with ISO 80000-7:2019 and the International Electrotechnical
Vocabulary.
b) Normative references: IEC 61040:1990 has been removed because it was withdrawn in August 2011.
c) In 3.1, the definition of RIN has been corrected. The word “relative intensity noise spectral density” has
been replaced by “spectral relative intensity noise”.
d) In Figure 2, keys 4, 5 and 6 have been amended.
e) In 6.3, the explanatory text has been added instead of referencing IEC 61040:1990.
f) In 6.5,The term “laser power density” has been replaced by “irradiance” in order to align with
ISO 80000-7: 2019.
g) In 7.9, measurement procedure has been modified to clarify the method for removing thermal and shot
noise terms as well as pre-amplifier noise from the measured noise power.
h) In Clause 9 c) 5), the terms “current or energy input”, “pulse energy”, “pulse duration” and “pulse
repetition rate” have been modified in order to clarify their characteristics.

iv
ISO 11554:2025(en)
i) In Annex A, the word “spectral density of the power fluctuations” and “spectral density function S ( f )”
ΔP
have been replaced by “spectral irradiation fluctuations” and “power spectrum S ( f )”, respectively.
ΔP
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

v
ISO 11554:2025(en)
Introduction
The measurement of laser radiant power (radiant energy for pulsed lasers) is a common type of measurement
performed by laser manufacturers and users. Radiant power (radiant energy) measurements are needed for
laser safety classification, stability specifications, maximum laser output specifications, damage avoidance,
specific application requirements, etc. This document provides guidance on performing laser radiant power
(radiant energy) measurements as applied to stability characterization. The stability criteria are described
for various temporal regions (e.g. short-term, medium term and long term) and provide methods to quantify
these specifications. This document also covers pulse measurements where detector response speed can
be critically important when analysing pulse shape or peak radiant power of short pulses. To standardize
reporting of radiant power (radiant energy) measurement results, a report template is also included.

vi
International Standard ISO 11554:2025(en)
Optics and photonics — Lasers and laser-related equipment
— Test methods for laser beam radiant power, radiant energy
and temporal characteristics
1 Scope
This document specifies test methods for determining the radiant power and radiant energy of continuous
wave and pulsed laser beams, as well as their temporal characteristics of pulse shape, pulse duration and
pulse repetition rate. Test and evaluation methods are also given for the radiant power stability of cw-lasers,
radiant energy stability of pulsed lasers and pulse duration stability.
The test methods given in this document are used for the testing and characterization of lasers.
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.
ISO 11145, Optics and photonics — Lasers and laser-related equipment — Vocabulary and symbols
ISO/IEC Guide 99, International vocabulary of metrology — Basic and general concepts and associated terms (VIM)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11145, ISO/IEC Guide 99 and the
following apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
relative intensity noise
RIN
R( f )
quotient of the radiant power mean square fluctuations to the square of the mean radiant power, normalized
to a frequency band of unit width
ΔPf
()
Rf =·
()
Δf
P
where Δf is the equivalent noise bandwidth.
Note 1 to entry: The relative intensity noise R( f ) or RIN [see Formula] is explicitly spoken of as the “spectral relative
intensity noise”, but usually simply referred to as RIN.
Note 2 to entry: For further details, see Annex A.

ISO 11554:2025(en)
3.2
small signal cut off frequency
f
c
frequency at which the laser radiant power output modulation drops to half the value obtained at low
frequencies when applying small, constant input radiant power modulation and increasing the frequency
4 Symbols and units of measurement
The symbols and units specified in ISO 11145 and in Table 1 are used in this document.
Table 1 — Symbols and units of measurement
Symbol Unit Term
f Hz Frequency
f Hz Small signal cut-off frequency
c
[ f ,f ] Hz Frequency range for which the relative intensity noise R( f ) is given
1 2
k 1 Coverage factor for the determination of uncertainty
m
1 Reading
m 1 Mean value of readings
P W Radiant power averaged over the sampling period
Mean radiant power, averaged over the measurement period at the operating
W
P
conditions specified by the manufacturer
Relative radiant power fluctuation to a 95 % confidence level for the appro-
ΔP 1 priate sampling period [ΔP (1 µs) and/or ΔP (1 ms) and/or ΔP (0,1 s) and/or
ΔP (1 s)]
J Mean pulse radiant energy
Q
ΔQ 1 Relative pulse radiant energy fluctuation to a 95 % confidence level
-1
R( f ) Hz or dB/Hz Relative intensity noise, RIN
S(t) 1 Detector signal
s 1 Measured standard deviation
T s Pulse repetition period
t s Measurement period
Expanded relative uncertainty corresponding to a 95 % confidence level (cov-
U 1
rel
erage factor k = 2)
Expanded relative uncertainty of calibration corresponding to a 95 % confi-
U (C) 1
rel
dence level (coverage factor k = 2)
τ s Fall time of laser pulse
F
Relative pulse duration fluctuation with regard to τ to a 95 % confidence
H
Δτ 1
H
level
τ s Rise time of laser pulse
R
Relative pulse duration fluctuation with regard to τ to a 95 % confidence
Δτ 1
level
[1]
NOTE 1 For further details regarding 95 % confidence level see ISO 2602 .
NOTE 2 The expanded uncertainty is obtained by multiplying the standard uncertainty by a coverage factor k = 2. It
[3]
is determined according to ISO/IEC Guide 98-3 . In general, with this coverage factor, the value of the measurand lies
with a probability of approximately 95 % within the interval defined by the expanded uncertainty.
-1
NOTE 3 R( f ) expressed in dB/Hz equals 10 log R( f ) with R( f ) given in Hz .
ISO 11554:2025(en)
5 Measurement principles
The laser beam is directed on to the detector surface to produce a signal with amplitude proportional to the
radiant power or radiant energy of the laser. The amplitude versus time is measured. Radiation emitted by
sources with large divergence angles is collected by an integrating sphere. Beam forming and attenuation
devices may be used when appropriate.
The evaluation method depends on the parameter to be determined and is described in Clause 8.
6 Measurement configuration, test equipment and auxiliary devices
6.1 Preparation
6.1.1 Sources with small divergence angles
The laser beam and the optical axis of the measuring system shall be coaxial. Select the diameter (cross-
section) of the optical system such that it accommodates the entire cross section of the laser beam and so
that clipping or diffraction loss is smaller than 10 % of the intended measurement uncertainty.
Arrange an optical axis so that it is coaxial with the laser beam to be measured. Suitable optical alignment
devices are available for this purpose (e.g. aligning lasers or steering mirrors). Mount the attenuators or
beam forming optics such that the optical axis runs through the geometrical centres. Care should be
exercised to avoid systematic errors.
NOTE 1 Reflections, external ambient light, thermal radiation and air currents are all potential sources of errors.
After the initial preparation is completed, make an evaluation to determine if the entire laser beam reaches
the detector surface. For this determination, apertures of different diameters can be introduced into the
beam path in front of each optical component. Reduce the aperture size until the output signal has been
reduced by 5 %. This aperture should have a diameter at least 20 % smaller than the aperture of the optical
component. For divergent beams, the aperture should be placed immediately in front of the detector to
ensure total beam capture.
NOTE 2 Remove these apertures before performing the radiant power (radiant energy) measurements described in
Clause 7.
6.1.2 Sources with large divergence angles
The radiation emitted by sources with large divergence angles shall be collected by an integrating sphere.
The collected radiation is subjected to multiple reflections from the wall of the integrating sphere; this leads
to a uniform irradiance of the surface proportional to the collected flux. A detector located in the wall of
the sphere measures this irradiance. An opaque screen shields the detector from the direct radiation of the
device being measured. The emitting device is position
...