SIST EN ISO 11146-1:2021

Lasers and laser-related equipment - Test methods for laser beam widths, divergence angles and beam propagation ratios - Part 1: Stigmatic and simple astigmatic beams (ISO 11146-1:2021)

This document specifies methods for measuring beam widths (diameter), divergence angles and beam propagation ratios of laser beams. This document is only applicable for stigmatic and simple astigmatic beams. If the type of the beam is unknown, and for general astigmatic beams, ISO 11146‑2 is applicable.

Laser und Laseranlagen - Prüfverfahren für Laserstrahlabmessungen, Divergenzwinkel und Beugungsmaßzahlen - Teil 1: Stigmatische und einfach astigmatische Strahlen (ISO 11146-1:2021)

Dieses Dokument legt Verfahren zur Messung von Strahlabmessungen (Strahldurchmesser), Divergenz-winkeln und Beugungsmaßzahlen von Laserstrahlen fest. Dieses Dokument ist nur für stigmatische und einfach astigmatische Strahlen anzuwenden. Wenn die Art des Strahles unbekannt ist und bei allgemein astigmatischen Strahlen, ist ISO 11146 2 anzuwenden.

Lasers et équipements associés aux lasers - Méthodes d'essai des largeurs du faisceau, angles de divergence et facteurs de limite de diffraction - Partie 1: Faisceaux stigmatiques et astigmatiques simples (ISO 11146-1:2021)

Le présent document spécifie les méthodes pour mesurer les largeurs (diamètres) du faisceau, les angles de divergence et les facteurs de limite de diffraction. Le présent document s'applique uniquement aux faisceaux stigmatiques et astigmatiques simples. Si le type de faisceau est inconnu et pour les faisceaux astigmatiques généraux, l'ISO 11146‑2 s'applique.

Laserji in laserska oprema - Preskusne metode za širine laserskega žarka, kota divergence in faktorja širjenja žarkov - 1. del: Stigmatični in enostavni astigmatični žarki (ISO 11146-1:2021)

General Information

• Status: Published
• Public Enquiry End Date: 19-Jul-2020
• Publication Date: 22-Aug-2021
• ICS: 31.260 - Optoelectronics. Laser equipment
• Technical Committee: VAZ - Healthcare
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 28-Jul-2021
• Due Date: 02-Oct-2021
• Completion Date: 23-Aug-2021
• Ref Project: EN ISO 11146-1:2021 - Lasers and laser-related equipment - Test methods for laser beam widths, divergence angles and beam propagation ratios - Part 1: Stigmatic and simple astigmatic beams (ISO 11146-1:2021)

Relations

• Replaces: SIST EN ISO 11146-1:2005 - Lasers and laser-related equipment - Test methods for laser beam widths, divergence angles and beam propagation ratios - Part 1: Stigmatic and simple astigmatic beams (ISO 11146-1:2005)
• Effective Date: 01-Sep-2021

Overview

EN ISO 11146-1:2021 (ISO 11146-1:2021) specifies standardized test methods for characterizing laser beams - in particular beam widths (diameter), divergence angles and beam propagation ratios - for stigmatic and simple astigmatic beams. The standard defines measurement principles based on the method of second order moments (within the paraxial approximation), the required measurement arrangements, detector and optics considerations, and the content of the test report. For beams of unknown type or for general astigmatic beams, ISO 11146-2 applies.

Key Topics and Requirements

• Scope and applicability: Measurement methods are limited to stigmatic and simple astigmatic beams; other beam types are covered in ISO 11146-2.
• Measurement principle: Beam characterization uses second order moments of the power (energy) density distribution to define beam widths and propagation parameters.
• Coordinate systems and principal axes: The standard clarifies coordinate definitions (including principal axes x' and y') used in evaluations.
• Test arrangement and equipment: Requirements for detector systems, beam-forming optics, optical attenuators, focusing systems and environmental controls are specified to ensure repeatable, traceable measurements.
• Measurement procedures: Step-by-step procedures for measuring beam width, divergence angle and combined determination of beam waist, beam widths, divergence and beam propagation ratio (M2) are provided.
• Evaluation and reporting: Guidelines for data evaluation, integration ranges for second order moments (note: integration requirements were relaxed in this edition), and minimum test-report content are included.
• Alternatives and correlation: ISO/TR 11146-3 describes alternative beam width measurement methods (variable aperture, moving knife-edge, moving slit) and their correlation with the second-moment method.

Practical Applications and Users

This standard is essential for professionals who need reliable, comparable laser beam characterization:

• Laser manufacturers - specification, QA and production testing of laser sources.
• Test and calibration laboratories / metrology institutes - standardized measurement procedures for traceable results.
• Optical system integrators and R&D teams - beam quality (M2), divergence and waist location for system design and simulation.
• Medical, industrial and telecommunications engineers - performance verification for processing, imaging and free-space links.
• Regulatory and safety specialists - supporting documentation for compliance and safety assessments.

Using EN ISO 11146-1:2021 helps ensure consistent, repeatable measurement of critical beam parameters, improving product specifications, process control and interoperability across photonics applications.

Related Standards

• ISO 11146-2 - General astigmatic beams (when beam type is unknown or more complex).
• ISO/TR 11146-3 - Technical report on theoretical background and alternative methods.
• ISO 11145 - Vocabulary and symbols (harmonized terms).
• ISO 13694 - Power (energy) density distribution test methods.

Standards Content (Sample)

SLOVENSKI STANDARD
01-september-2021
Nadomešča:
SIST EN ISO 11146-1:2005
Laserji in laserska oprema - Preskusne metode za širine laserskega žarka, kota
divergence in faktorja širjenja žarkov - 1. del: Stigmatični in enostavni astigmatični
žarki (ISO 11146-1:2021)
Lasers and laser-related equipment - Test methods for laser beam widths, divergence
angles and beam propagation ratios - Part 1: Stigmatic and simple astigmatic beams
(ISO 11146-1:2021)
Laser und Laseranlagen - Prüfverfahren für Laserstrahlabmessungen, Divergenzwinkel
und Beugungsmaßzahlen - Teil 1: Stigmatische und einfach astigmatische Strahlen (ISO
11146-1:2021)
Lasers et équipements associés aux lasers - Méthodes d'essai des largeurs du faisceau,
angles de divergence et facteurs de limite de diffraction - Partie 1: Faisceaux
stigmatiques et astigmatiques simples (ISO 11146-1:2021)
Ta slovenski standard je istoveten z: EN ISO 11146-1:2021
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 11146-1
EUROPEAN STANDARD
NORME EUROPÉENNE
July 2021
EUROPÄISCHE NORM
ICS 31.260 Supersedes EN ISO 11146-1:2005
English Version
Lasers and laser-related equipment - Test methods for
laser beam widths, divergence angles and beam
propagation ratios - Part 1: Stigmatic and simple
astigmatic beams (ISO 11146-1:2021)
Lasers et équipements associés aux lasers - Méthodes Laser und Laseranlagen - Prüfverfahren für
d'essai des largeurs du faisceau, angles de divergence Laserstrahlabmessungen, Divergenzwinkel und
et facteurs de limite de diffraction - Partie 1: Faisceaux Beugungsmaßzahlen - Teil 1: Stigmatische und einfach
stigmatiques et astigmatiques simples (ISO 11146- astigmatische Strahlen (ISO 11146-1:2021)
1:2021)
This European Standard was approved by CEN on 4 July 2021.

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, Turkey 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
© 2021 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 11146-1:2021 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 11146-1:2021) 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 January 2022, and conflicting national standards shall
be withdrawn at the latest by January 2022.
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 11146-1:2005.
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 websites.
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, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 11146-1:2021 has been approved by CEN as EN ISO 11146-1:2021 without any
modification.
INTERNATIONAL ISO
STANDARD 11146-1
Second edition
2021-07
Lasers and laser-related equipment —
Test methods for laser beam
widths, divergence angles and beam
propagation ratios —
Part 1:
Stigmatic and simple astigmatic
beams
Lasers et équipements associés aux lasers — Méthodes d'essai des
largeurs du faisceau, angles de divergence et facteurs de limite de
diffraction —
Partie 1: Faisceaux stigmatiques et astigmatiques simples
Reference number
ISO 11146-1:2021(E)
©
ISO 2021
ISO 11146-1:2021(E)
© ISO 2021
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: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2021 – All rights reserved

ISO 11146-1:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Coordinate systems . 7
5 Test principles . 7
5.1 Applicability . 7
5.2 Beam widths and beam diameter . 7
5.3 Beam divergence angles . 8
5.4 Beam propagation ratios . 8
5.5 Combined measurement of beam waist locations, beam widths, beam divergence
angles and beam propagation ratios . 8
6 Measurement arrangement and test equipment . 8
6.1 General . 8
6.2 Preparation . 8
6.3 Control of environment . 9
6.4 Detector system . 9
6.5 Beam-forming optics and optical attenuators . 9
6.6 Focusing system .10
7 Beam widths and beam diameter measurement .10
7.1 Test procedure .10
7.2 Evaluation .10
8 Measurement of divergence angles .12
8.1 Test procedure .12
8.2 Evaluation .12
9 Combined determination of beam waist locations, beam widths, divergence angles
and beam propagation ratios .12
10 Test report .14
Bibliography .17
ISO 11146-1:2021(E)
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 documents 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).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www .iso .org/ patents).
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 second edition cancels and replaces the first edition (ISO 11146-1:2005), which has been technically
revised. The main changes compared to the previous edition are as follows:
— The terms and definitions were harmonized with the new edition of ISO 11145.
— The "principal axes" were defined more thoroughly and named as x' and y'. Quantities related to the
principal axes coordinate system refer to this definition and use x' and y' in their indices.
— The requirements for the integration range for the determination of the second order moments
have been relaxed.
A list of all parts in the ISO 11146 series can be found on the ISO website.
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.
iv © ISO 2021 – All rights reserved

ISO 11146-1:2021(E)
Introduction
The propagation properties of every laser beam can be characterized within the method of second order
moments by ten independent parameters (see ISO/TR 11146-3). However, due to their higher symmetry
most laser beams of practical interest need fewer parameters for a complete description. Most lasers of
practical use emit beams which are stigmatic or simple astigmatic because of their resonator design.
This document describes the measurement methods for stigmatic and simple astigmatic beams while
ISO 11146-2 deals with the measurement procedures for general astigmatic beams. For beams of
unknown type the methods of ISO 11146-2 are applicable. Beam characterization based on the method
of second order moments as described in both parts is only valid within the paraxial approximation.
The theoretical description of beam characterization and propagation as well as the classification of
laser beams is given in ISO/TR 11146-3, which is a Technical Report and describes the procedures for
background subtraction and offset correction.
In this document, the second order moments of the power (energy) density distribution are used for the
determination of beam widths. However, there may be problems experienced in the direct measurement
of these quantities in the beams from some laser sources. In this case, other indirect methods of the
measurement of the second order moments may be used as long as comparable results are achievable.
In ISO/TR 11146-3, three alternative methods for beam width measurement and their correlation with
the method used in this document are described. These methods are:
— variable aperture method;
— moving knife-edge method;
— moving slit method.
INTERNATIONAL STANDARD ISO 11146-1:2021(E)
Lasers and laser-related equipment — Test methods
for laser beam widths, divergence angles and beam
propagation ratios —
Part 1:
Stigmatic and simple astigmatic beams
1 Scope
This document specifies methods for measuring beam widths (diameter), divergence angles and beam
propagation ratios of laser beams. This document is only applicable for stigmatic and simple astigmatic
beams. If the type of the beam is unknown, and for general astigmatic beams, ISO 11146-2 is applicable.
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 11146-2, Lasers and laser-related equipment — Test methods for laser beam widths, divergence angles
and beam propagation ratios — Part 2: General astigmatic beams
ISO 13694, Optics and photonics — Lasers and laser-related equipment — Test methods for laser beam
power (energy) density distribution
EN 61040:1992, Power and energy measuring detectors, instruments and equipment for laser radiation
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11145, ISO 13694, EN 61040
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/
NOTE The x-, y- and z-axes in these definitions refer to the laboratory system as described in Clause 4. Here
and throughout this document the term “power density distribution E(x,y,z)” refers to continuous wave sources.
It might be replaced by “energy density distribution, H(x,y,z)” in case of pulsed sources.
ISO 11146-1:2021(E)
3.1
first order moments of a power density distribution
xy,
centroid coordinates of the power density distribution of a cross section of a beam given as
∞ ∞
Ex (),,yz xxy dd
∫ ∫
−∞−∞
xz()= (1)
∞ ∞
Ex (),,yz ddxy
∫ ∫
−∞−∞
and
∞ ∞
Ex (),,yz yx ddy
∫ ∫
−∞−∞
yz()= (2)
∞ ∞
Ex (),,yz ddxy
∫ ∫
−∞−∞
Note 1 to entry: The first order moments are used for the definition of beam centroid in ISO 11145.
Note 2 to entry: For practical application, the infinite integration limits are reduced in a specific manner as given
in Clause 7. The limitation of the integration area here differs from the integration area given in ISO 11145.
3.2
second order moments of a power density distribution
22 2
σσ,, σ
xy xy
normalized weighted integrals over the power density distribution, given as:
∞ ∞
Ex,,yz xx− zx ddy
() ()
 
∫∫
−∞ −∞
σ zx== (3)
()
x
∞ ∞
Ex,,yz dxxyd
()
∫∫
−∞ −∞
and
∞ ∞
Ex,,yz yy− zx ddy
() ()
 
∫∫
−∞ −∞
σ zy== (4)
()
y
∞ ∞
Ex,,yz dxxyd
()
∫∫
−∞ −∞
and
∞ ∞
Ex,,yz xx− zy  − yz ddxy
() () ()
   
∫∫
−∞ −∞
σ zx==y (5)
()
xy
∞ ∞
Ex,,yz ddxy
()
∫ ∫∫
−∞ −∞
Note 1 to entry: For practical application, the infinite integration limits are reduced in a specific manner as given
in Clause 7.
Note 2 to entry: σ z is a symbolic notation, and not a true square. This quantity can take positive, negative
()
xy
or zero value.
Note 3 to entry: The angular brackets are the operator notations as used in ISO 11146-2 and ISO/TR 11146-3.
2 © ISO 2021 – All rights reserved

ISO 11146-1:2021(E)
3.3
principal axes
x’, y’
axes of the maximum and minimum beam extent based on the second
order moments of the power density distribution in a cross section of the beam
Figure 1 — Beam profile with the laboratory and principle axes coordinate systems
Note 1 to entry: The axes of maximum and minimum extent are always perpendicular to each other.
Note 2 to entry: Unless otherwise stated, in this document x’ is the principal axis which is closer to the x-axis
of the laboratory coordinate system, and y’ is the principal axis which is closer to the y-axis of the laboratory
coordinate system.
Note 3 to entry: If the principal axes make the angle π/4 with the x- and y-axes of the laboratory coordinate
system, then the x’-axis is by convention the direction of maximum extent.
Note 4 to entry: See Figure 1.
3.4
azimuthal orientation
φ
azimuthal angle between the x-axis of the laboratory system and the
principal axis x’
ISO 11146-1:2021(E)
3.5
beam widths
d (z ), d (z )
σx’ 0x’ σy’ 0y’
extent of a power density distribution in a cross-section of the beam at an axial location z along the
principal axes x’ and y’, respectively, based on the second order moments of the power density
distribution
Note 1 to entry: This definition differs from that given in ISO 11145:2018, 3.5.2, where the beam widths are
defined only in the laboratory system, whereas for the purposes of this document the beam widths are defined in
the principal axes (3.3) system of the beam.
Note 2 to entry: Formulae for calculation of the beam widths from the three second order moments are given in
7.2.
3.6
beam ellipticity
ε(z)
parameter for quantifying the circularity or squareness of a power (energy) density distribution at an
axial location z
 
min dz() , dz()
σσxy''
 
ε ()z =
 
max dz , dz
() ()
σσxy''
 
Note 1 to entry: It follows that 01<ε z ≤ .
()
Note 2 to entry: If ε(z) ≥ 0,87, elliptical distributions can be regarded as circular.
Note 3 to entry: In case of a rectangular distribution, ellipticity is often referred to as “aspect ratio”.
Note 4 to entry: In contrast to the definition given here, in literature the term “ellipticity” is sometimes related to
dz()
′
σ y
1− . The definition given here has been chosen to be in concordance with the same definition of ellipticity
dz()
′
σx
in ISO 11145 and ISO 13694.
3.7
circular power density distribution
power density distribution having an ellipticity greater than or equal to 0,87
[SOURCE: ISO 11145:2018, 3.6.4]
3.8
beam diameter
d (z)
σ
extent of a circular power density distribution in a cross section of the beam at an axial location z,
based on the second order moments
Note 1 to entry: Formulae for calculation of the beam diameter from the second order moments are given in 7.2.
3.9
stigmatism
property
...