EN ISO 13694:2018

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Optics and photonics - Lasers and laser-related equipment - Test methods for laser
beam power (energy) density distribution (ISO 13694:2018)
Optik und Photonik - Laser und Laseranlagen - Prüfverfahren für die Leistungs-(Energie
-)dichteverteilung von Laserstrahlen (ISO 13694:2018)
Optique et photonique - Lasers et équipements associés aux lasers - Méthodes d'essai
de distribution de la densité de puissance (d'énergie) du faisceau laser (ISO
13694:2018)
Ta slovenski standard je istoveten z: EN ISO 13694:2018
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 13694
EUROPEAN STANDARD
NORME EUROPÉENNE
December 2018
EUROPÄISCHE NORM
ICS 31.260 Supersedes EN ISO 13694:2015
English Version
Optics and photonics - Lasers and laser-related equipment
- Test methods for laser beam power (energy) density
distribution (ISO 13694:2018)
Optique et photonique - Lasers et équipements Optik und Photonik - Laser und Laseranlagen -
associés aux lasers - Méthodes d'essai de distribution Prüfverfahren für die Leistungs-(Energie-
de la densité de puissance (d'énergie) du faisceau laser )dichteverteilung von Laserstrahlen (ISO 13694:2018)
(ISO 13694:2018)
This European Standard was approved by CEN on 23 September 2018.

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, Former Yugoslav Republic of Macedonia, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania,
Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, 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
© 2018 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 13694:2018 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 13694:2018) 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 June 2019, and conflicting national standards shall be
withdrawn at the latest by June 2019.
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 13694:2015.
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, Former Yugoslav Republic of Macedonia,
France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta,
Netherlands, Norway, Poland, Portugal, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland,
Turkey and the United Kingdom.
Endorsement notice
The text of ISO 13694:2018 has been approved by CEN as EN ISO 13694:2018 without any modification.

INTERNATIONAL ISO
STANDARD 13694
Third edition
2018-11
Optics and photonics — Lasers and
laser-related equipment — Test
methods for laser beam power
(energy) density distribution
Optique et photonique — Lasers et équipements associés aux
lasers — Méthodes d'essai de distribution de la densité de puissance
(d'énergie) du faisceau laser
Reference number
ISO 13694:2018(E)
©
ISO 2018
ISO 13694:2018(E)
© ISO 2018
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
Fax: +41 22 749 09 47
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved

ISO 13694:2018(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Measured quantities . 1
3.2 Characterizing parameters . 3
4 Coordinate system . 7
5 Characterizing parameters derived from the measured spatial distribution .7
6 Test principle . 7
7 Measurement arrangement and test equipment . 8
7.1 General . 8
7.2 Preparation . 8
7.3 Control of environment . 8
7.4 Detector system . 8
7.5 Beam-forming optics, optical attenuators, and beam splitters . 9
8 Test procedure . 9
8.1 Equipment preparation . 9
8.2 Detector calibration procedure .10
8.2.1 Spatial calibration .10
8.2.2 Power (energy) calibration .10
8.3 Data recording and noise correction .10
8.3.1 General.10
8.3.2 Correction by background-map subtraction .11
8.3.3 Correction by average background subtraction.11
9 Evaluation .12
10 Test report .12
Annex A (informative) Test report .13
Bibliography .16
ISO 13694:2018(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.
This third edition cancels and replaces the second edition (ISO 13694:2015), which has been technically
revised. The main changes compared to the previous edition are as follows:
a) the definition of beam ellipticity has been harmonized with ISO 11145 and ISO 11146-1;
b) the term “second linear moments” has been replaced by “second moments”;
c) the term “field of view” has been replaced by “aperture”;
d) Clause 9 was rewritten; the paragraphs on clip-levels were corrected to reflect that they are no
longer intended for noise cancelation;
e) the entries “Fitted distribution type”, “Roughness of fit R”, and “Goodness of fit G” have been
removed from the Test Report;
f) the term “aspect ratio” has been removed from the test report.
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 2018 – All rights reserved

ISO 13694:2018(E)
Introduction
Many applications of lasers involve using the near-field as well as the far-field power (energy) density
distribution of the beam. The power (energy) density distribution of a laser beam is characterized by the
spatial distribution of irradiant power (energy) density with lateral displacement in a particular plane
perpendicular to the direction of propagation. In general, the power (energy) density distribution of the
beam changes along the direction of propagation. Depending on the power (energy), size, wavelength,
polarization, and coherence of the beam, different methods of measurement are applicable in different
situations. Five methods are commonly used: camera arrays (1D and 2D), apertures, pinholes, slits, and
knife edges.
According to ISO 11145, it is possible to use two different definitions for describing and measuring the
laser beam diameter. One definition is based on the measurement of the encircled power (energy); the
other is based on determining the spatial moments of the power (energy) density distribution of the
laser beam.
The use of spatial moments is necessary for calculating the beam propagation factor, K, and the
beam propagation ratio, M , from measurements of the beam widths at different distances along the
propagation axis. ISO 11146-1 describes this measurement procedure. For other applications, other
definitions for the beam diameter can be used. For some quantities used in this document the first
definition (encircled power (energy)) is more appropriate and easier to use.
INTERNATIONAL STANDARD ISO 13694:2018(E)
Optics and photonics — Lasers and laser-related
equipment — Test methods for laser beam power (energy)
density distribution
1 Scope
This document specifies methods by which the measurement of power (energy) density distribution is
made and defines parameters for the characterization of the spatial properties of laser power (energy)
density distribution functions at a given plane.
The methods given in this document are intended to be used for the testing and characterization of
both continuous wave (cw) and pulsed laser beams used in optics and optical instruments.
This document provides definitions of terms and symbols to be used in referring to power density
distribution, as well as requirements for its measurement. For pulsed lasers, the distribution of time-
integrated power density (i.e. energy density) is the quantity most often measured.
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 — Laser and laser-related equipment — Vocabulary and symbols
ISO 11146-1, 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 11554, Optics and photonics — Lasers and laser-related equipment — Test methods for laser beam
power, energy and temporal characteristics
IEC 61040, 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 and IEC 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 http: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
3.1 Measured quantities
3.1.1
power density distribution
E(x, y, z)
set of all power densities at location z of a certain cw beam with non-negative values for all transverse
coordinates (x, y)
ISO 13694:2018(E)
3.1.1.1
power density
E(x , y , z)
P P
portion of the beam power at location z which impinges on the area δA at the location P(x , y ) divided
P P
by the area δA in the limit δA → 0
[SOURCE: ISO 11145:2018, 3.13.6, modified —Notes to entry omitted.]
3.1.2
energy density distribution
H(x, y, z)
set of all energy densities at location z of a certain pulsed beam with non-negative values for all
transverse coordinates (x, y)
Hx,,yz = Ex,,yz dt
() ()
∫
3.1.2.1
energy density
H(x , y , z)
P P
portion of the beam energy (time-integrated power) at location z which impinges
on the area δA at the location P(x , y ) divided by the area δA in the limit δA → 0
P P
Hx ,,yz = Ex ,,yz dt
() ()
PP PP
∫
[SOURCE: ISO 11145:2018, 3.13.4, modified — Notes to entry omitted and Formula added.]
3.1.3
power
P(z)
rate of energy transfer in a continuous wave (cw) beam at location z
Pz = Ex,,yz ddxy
() ()
∫∫
3.1.4
pulse energy
Q(z)
energy in one pulse measured at location z
Qz = Hx,,yz ddxy
() ()
∫∫
[SOURCE: ISO 11145:2018, term 3.13.3 modified — Included "Measured at location z" and formula Q(z)]
3.1.5
maximum power (energy) density
E (z) [H (z)]
max max
maximum of the spatial power (energy) density distribution function E (x, y, z) [H (x, y, z)] at location z
3.1.6
location of the maximum
(x , y , z)
max max
location of E (z) or H (z) in the xy plane at location z
max max
Note 1 to entry: (x , y , z) cannot be uniquely defined when measuring with detectors having a high spatial
max max
resolution and a relatively small dynamic range.
2 © ISO 2018 – All rights reserved

ISO 13694:2018(E)
3.1.7
clip-level power (energy) density
E (z) [H (z)]
ηCL ηCL
fraction η of the maximum power (energy) density (3.1.5) at location z
Ez =ηEz
() ()
ηCL max
Hz =ηHz
() ()
ηCL max
0 ≤ η < 1
Note 1 to entry: When no confusion is possible, the explicit dependence on z is dropped in the text description
using some quantities, but not in the definitions or in the Formulae involving the quantities.
3.2 Characterizing parameters
3.2.1
clip-level power (energy)
P (z) [Q (z)]
η η
integral of the power (energy) distribution at location z, evaluated by summing only over locations (x,y)
for which E (x, y, z) > E (z) [H (x, y, z) > H (z)]
ηCL ηCL
3.2.2
fractional power (energy)
f (z)
η
fraction of the clip-level power (energy) (3.2.1) for a given η to the total power (energy) in the distribution
at location z
Pz
()
η
fz =  for cw-beams
()
η
Pz
()
Qz
()
η
fz =  for pulsed beams
()
η
Qz
()
0 ≤ f (z) ≤ 1
η
3.2.3
beam centroid
xz , yz
() ()
()
coordinates of the first-order moments of a power(energy) distribution of a beam at location z
xE⋅ xy,,zx⋅ddy
()
∫∫
xz =
()
Ex,,yz ⋅ddxy
()
∫∫
yE⋅ xy,,zx⋅ddy
()
∫∫
yz =
()
Ex,,yz ⋅ddxy
()
∫∫
where the integration shall be performed over an area such that at least 99 % of the beam power
(energy) is captured
Note 1 to entry: The power density E is replaced by the energy density H for pulsed lasers.
Note 2 to entry: For a more detailed definition, see ISO 11145 and ISO 11146-1.
ISO 13694:2018(E)
3.2.4
beam widths
d (z), d (z)
σx σy
widths d (z) and d (z) of the beam in the respective x and y directions at z, equal to four times the
σx σy
square root of the second moments of the power (energy) density distribution about the centroid
Note 1 to entry: For a more detailed definition, see ISO 11145 and ISO 11146-1.
Note 2 to entry: The provisions of ISO 11146-1 apply to definitions and measurements of:
a) second moment beam widths d and d ;
σx σy
b) beam widths d and d in terms of the smallest centred slit width that transmits u % of the total power
x,u y,u
(energy) density (usually u = 86,5);
c) scanning narrow slit measurements of beam widths d and d in terms of the separation between positions
x,s y,s
where the transmitted power density (3.1.1.1) is reduced to 0,135 E , where E is the peak power (energy)
p p
density;
d) measurements of beam widths d and d in terms of the separation between 0,84 P and 0,16 P obscuration
x,k y,k
positions of a movable knife-edge, where P is the maximum, unobstructed power (energy) recorded by the
large area detector behind the knife-edge plane;
e) correlation factors which relate these different definitions and methods for measuring beam widths.
3.2.5
beam ellipticity
ε (z)
parameter for quantifying the circularity or squareness of a power (energy) distribution at z
dz
()
σ y
ε z =
()
dz
()
σx
where the direction of x is chosen to be along the major axis of the distribution, such that d ≥ d
σx σy
Note 1 to entry: If ε ≥ 0,87, elliptical distributions can be regarded as circular.
Note 2 to entry: In case of a rectangular distribution, ellipticity is often referred to as aspect ratio.
Note 3 to entry: Technically identical to ISO 11146-1 and ISO 11145.
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 11146-1 and ISO 11145.
3.2.6
beam cross-sectional area
A (z)
σ
area of a beam with circular
cross-section
 π 2
Ad= ⋅ ()z
σσ 
 
or elliptical cross-section
π
 
Ad= ⋅ zd⋅ z
() ()
σσxyσ
 
 
4 © ISO 2018 – All rights reserved

ISO 13694:2018(E)
Note 1 to entry: For clarity, the term “beam cross-sectional area” is always used in combination with the symbol
and its appropriate subscript: A or A .
u σ
[SOURCE: ISO 11145:2018, 3.6.2]
3.2.7
clip-level irradiation area
i
Az
()
η
irradiation area at location z for which the power (energy) density exceeds the clip-level power (energy)
density (3.1.7)
Note 1 to entry: To allow for distributions of all forms, for example hollow “donut” types, the clip-level irradiation
area is not defined in terms of the beam widths (3.2.4) d or d .
σx σy
Note 2 to entry: See clip-level power (energy) density (3.1.7).
3.2.8
clip-level average power (energy) density
E (z), [H (z)]
ηave ηave
spatially averaged power (energy) density of the distribution at location z, defined as the weighted mean
Pz
()
η
Ez()=  for cw-beams
ηave
i
Az
()
η
Qz
()
η
Hz =  for pulsed beams
()
ηave
i
Az
()
η
Note 1 to entry: E (z) and E (z) (see 3.1.7) refer to different parameters.
ηave ηCL
3.2.9
flatness factor
F (z)
η
ratio of the clip-level average power (ene
...