SIST EN ISO 11145:2019

Optics and photonics - Lasers and laser-related equipment - Vocabulary and symbols (ISO 11145:2018)

This document defines basic terms, symbols, and units of measurement for the field of laser technology
in order to unify the terminology and to arrive at clear definitions and reproducible tests of beam
parameters and laser-oriented product properties.
NOTE The laser hierarchical vocabulary laid down in this document differs from that given in IEC 60825–1.
ISO and IEC have discussed this difference and agree that it reflects the different purposes for which the two
standards serve. For more details, see informative Annex A.

Optik und Photonik - Laser und Laseranlagen - Begriffe und Formelzeichen (ISO 11145:2018)

Dieses Dokument definiert die grundlegenden Begriffe, Formelzeichen und Maßeinheiten für den Bereich der Lasertechnik, um den Sprachgebrauch zu vereinheitlichen und zu klaren Definitionen und reproduzier-baren Prüfungen der Laserparameter und laserbezogenen Produkteigenschaften zu kommen.
ANMERKUNG   Die hierarchisch gegliederte Begriffsbildung für Laser, wie sie in diesem Dokument angegeben ist, unterscheidet sich von der hierarchischen Begriffsbildung in IEC 60825 1. ISO und IEC haben diesen Unterschied beraten und sind übereingekommen, dass sie die beiden verschiedenen Zielsetzungen widerspiegelt, für die die beiden Normen entwickelt wurden. Genaueres ist im informativen Anhang A dargelegt.

Optique et photonique - Lasers et équipements associés aux lasers - Vocabulaire et symboles (ISO 11145:2018)

Le présent document définit les termes fondamentaux, les symboles et les unités de mesure à utiliser dans le domaine de la technologie laser de manière à unifier la terminologie et à établir des définitions claires et des essais reproductibles concernant les paramètres du faisceau et les propriétés des appareils à laser.
NOTE       Le vocabulaire hiérarchique relatif au laser proposé dans le présent document diffère de celui donné dans l'IEC 60825‑1. L'ISO et l'IEC ont discuté de cette différence et sont d'accord qu'elle reflète les divers besoins pour lesquels les deux normes sont nécessaires. Pour plus de détails, voir l'Annexe A informative.

Optika in fotonska tehnologija - Laserji in z laserji povezana oprema - Slovar in simboli (ISO 11145:2018)

Ta dokument določa osnovne izraze, simbole in merske enote za področje laserske tehnologije z namenom poenotenja terminologije ter določitve jasnih definicij in ponovljivih preskusov parametrov za žarke in lasersko usmerjene lastnosti izdelkov.
OPOMBA: Slovar laserske tehnologije v hierarhični obliki, kot je določen v tem dokumentu, se razlikuje od slovarja v standardu IEC 60825–1.
Mednarodna organizacija za standardizacijo (ISO) in Mednarodna komisija za elektroniko (IEC) sta se v razpravi o tej razliki strinjali, da odseva različne namene, za katere se ta dva
standarda uporabljata. Za več podrobnosti glej informativni dodatek A.

General Information

• Status: Published
• Public Enquiry End Date: 04-Oct-2017
• Publication Date: 06-Feb-2019
• ICS: 01.040.31 - Electronics (Vocabularies)
• ICS: 01.080.40 - Graphical symbols for use on electrical and electronics engineering drawings, diagrams, charts and in relevant technical product documentation
• ICS: 31.260 - Optoelectronics. Laser equipment
• Technical Committee: VAZ - Healthcare
• Current Stage: 6060 - National Implementation/Publication (Adopted Project)
• Start Date: 15-Jan-2019
• Due Date: 22-Mar-2019
• Completion Date: 07-Feb-2019
• Directive: 2006/42/EC - Directive 2006/42/EC of the European Parliament and of the Council of 17 May 2006 on machinery, and amending Directive 95/16/EC (recast)
• Mandate: M/396 - Mandate to CEN and Cenelec for standardisation in the field of machinery
• Ref Project: EN ISO 11145:2018 - Optics and photonics - Lasers and laser-related equipment - Vocabulary and symbols (ISO 11145:2018)

Relations

• Replaces: SIST EN ISO 11145:2016 - Optics and photonics - Lasers and laser-related equipment - Vocabulary and symbols (ISO 11145:2016)
• Effective Date: 01-Mar-2019

Standards Content (Sample)

SLOVENSKI STANDARD
SIST EN ISO 11145:2019
01-marec-2019
1DGRPHãþD
SIST EN ISO 11145:2016
Optika in fotonska tehnologija - Laserji in z laserji povezana oprema - Slovar in
simboli (ISO 11145:2018)
Optics and photonics - Lasers and laser-related equipment - Vocabulary and symbols
(ISO 11145:2018)
Optik und Photonik - Laser und Laseranlagen - Begriffe und Formelzeichen (ISO
11145:2018)
Optique et photonique - Lasers et équipements associés aux lasers - Vocabulaire et
symboles (ISO 11145:2018)
Ta slovenski standard je istoveten z: EN ISO 11145:2018
ICS:
01.040.31 Elektronika (Slovarji) Electronics (Vocabularies)
01.080.40 *UDILþQLVLPEROL]DXSRUDERY Graphical symbols for use on
ULVEDKGLDJUDPLKQDþUWLKY electrical and electronics
HOHNWURWHKQLNLLQHOHNWURQLNL engineering drawings,
WHUYXVWUH]QLWHKQLþQL diagrams, charts and in
SURL]YRGQLGRNXPHQWDFLML relevant technical product
documentation
31.260 Optoelektronika, laserska Optoelectronics. Laser
oprema equipment
SIST EN ISO 11145:2019 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

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SIST EN ISO 11145:2019

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SIST EN ISO 11145:2019


EN ISO 11145
EUROPEAN STANDARD

NORME EUROPÉENNE

December 2018
EUROPÄISCHE NORM
ICS 01.040.31; 01.080.40; 31.260 Supersedes EN ISO 11145:2016
English Version

Optics and photonics - Lasers and laser-related equipment
- Vocabulary and symbols (ISO 11145:2018)
Optique et photonique - Lasers et équipements Optik und Photonik - Laser und Laseranlagen - Begriffe
associés aux lasers - Vocabulaire et symboles (ISO und Formelzeichen (ISO 11145:2018)
11145:2018)
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 11145:2018 E
worldwide for CEN national Members.

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SIST EN ISO 11145:2019
EN ISO 11145:2018 (E)
Contents Page
European foreword . 3
Annex ZA (informative) Relationship between this European Standard and the essential
requirements of Directive 2006/42/EC aimed to be covered . 4

2

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SIST EN ISO 11145:2019
EN ISO 11145:2018 (E)
European foreword
This document (EN ISO 11145:2018) 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 11145:2016.
This document has been prepared under a mandate given to CEN by the European Commission and the
European Free Trade Association, and supports essential requirements of EU Directive(s).
For the relationship with EU Directive(s) see informative Annex ZA, which is an integral part of this
document.
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 11145:2018 has been approved by CEN as EN ISO 11145:2018 without any modification.
3

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SIST EN ISO 11145:2019
EN ISO 11145:2018 (E)
Annex ZA
(informative)

Relationship between this European Standard and the essential
requirements of Directive 2006/42/EC aimed to be covered
This European Standard has been prepared under a Commission’s standardization request M/396
(Machinery) "Mandate to CEN and Cenelec for standardisation in the field of machinery" to provide one
voluntary means of conforming to essential requirements of Directive 2006/42/EC of the European
Parliament and of the Council of 17 May 2006 on machinery, and amending Directive 95/16/EC
(recast).
Once this standard is cited in the Official Journal of the European Union under that Directive,
compliance with the normative clauses of this standard given in Table ZA.1 confers, within the limits of
the scope of this standard, a presumption of conformity with the corresponding essential requirements
of that Directive, and associated EFTA regulations.
Table ZA.1 — Correspondence between this European Standard and Directive 2006/42/EC
Essential Requirements of Clause(s)/sub-clause(s)
Remarks/Notes
Directive 2006/42/EC of this EN
1.5.10 3
1.5.12 3
WARNING 1 — Presumption of conformity stays valid only as long as a reference to this European
Standard is maintained in the list published in the Official Journal of the European Union. Users of this
standard should consult frequently the latest list published in the Official Journal of the European
Union.
WARNING 2 — Other Union legislation may be applicable to the product(s) falling within the scope of
this standard.

4

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SIST EN ISO 11145:2019
INTERNATIONAL ISO
STANDARD 11145
Fifth edition
2018-11
Optics and photonics — Lasers
and laser-related equipment —
Vocabulary and symbols
Optique et photonique — Lasers et équipements associés aux lasers
— Vocabulaire et symboles
Reference number
ISO 11145:2018(E)
©
ISO 2018

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SIST EN ISO 11145:2019
ISO 11145:2018(E)

COPYRIGHT PROTECTED DOCUMENT
© 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: [phone]
Fax: [phone]
Email: [e-mail]
Website: www.iso.org
Published in Switzerland
ii © ISO 2018 – All rights reserved

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SIST EN ISO 11145:2019
ISO 11145:2018(E)

Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
3.1 Beam position . 2
3.2 Beam axis . 2
3.3 Beam diameter . 3
3.4 Beam radius . 3
3.5 Beam width . 4
3.6 Beam cross-sectional area . 4
3.7 Beam waist . 5
3.8 Divergence . 7
3.9 Rayleigh length. 7
3.10 Beam parameter product . 8
3.11 Coherence . 8
3.12 Polarization . 9
3.13 Power and Energy .10
3.14 Pulse duration and repetition rate .11
3.15 Optical resonator.12
3.16 Mode .12
3.17 Spectral bandwidth .12
3.18 Relative intensity noise .13
3.19 Laser .13
3.20 Efficiency .14
4 Symbols and units of measurement .15
Annex A (informative) Explanation of the difference in terminology between IEC 60825-1
and ISO 11145 .17
Annex B (informative) List of symbols .18
Bibliography .19
Alphabetical index .20
© ISO 2018 – All rights reserved iii

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SIST EN ISO 11145:2019
ISO 11145:2018(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 fifth edition cancels and replaces the fourth edition ISO 11145:2016, which has been technically
revised. The main changes compared to the previous edition are as follows:
a) the term beam position has been renamed “beam centroid” and defined formally as a first-
order moment;
b) the term beam ellipticity has been clarified;
c) the term beam waist location has been included;
d) the term optical resonator has been included;
e) the term 10 % pulse duration has been generalized to a selected percentage pulse duration;
f) the formula in the term beam diameter has been adjusted;
g) the order of the terms has been adjusted.
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

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SIST EN ISO 11145:2019
INTERNATIONAL STANDARD ISO 11145:2018(E)
Optics and photonics — Lasers and laser-related
equipment — Vocabulary and symbols
1 Scope
This document defines basic terms, symbols, and units of measurement for the field of laser technology
in order to unify the terminology and to arrive at clear definitions and reproducible tests of beam
parameters and laser-oriented product properties.
NOTE The laser hierarchical vocabulary laid down in this document differs from that given in IEC 60825–1.
ISO and IEC have discussed this difference and agree that it reflects the different purposes for which the two
standards serve. For more details, see informative Annex A.
2 Normative references
There are no normative references in this document.
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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/
NOTE 1 The spatial distribution of the power (energy) density in a cross section of a laser beam does not
always have circular symmetry. In this document, all terms related to these spatial distributions are split into
those for beam cross sections with circular distributions and those for beam cross sections with non-circular
distributions. A circular beam is characterized by its radius, w, or diameter, d. For a non-circular beam, the beam
widths, d and d , for two orthogonal directions are given.
x y
NOTE 2 The spatial distributions of laser beams do not have sharp edges. Therefore, the power (energy)
values to which the spatial terms refer are defined. Depending on the application, different cut-off values can be
2
chosen (for example 1/e, 1/e , 1/10 of the peak value).
NOTE 3 This document uses the subscript u to denote a percentage. For example, the percentage of the total
beam power (energy) included in the value of a given parameter. When stating quantities marked by an index “u”,
“u” is replaced by the specific number, e.g. A for u = 90 %.
90
NOTE 4 The beam width d (see 3.5.1) and the beam diameter d (see 3.3.1) can differ for the same value of u
x,u u
(d ≠ d ).
x,u u
NOTE 5 In contrast to quantities defined by setting a cut-off value [“encircled power (energy)”], the beam
widths and derived beam properties can also be defined based on the second moments of the power (energy)
density distribution function (see 3.5.2). Only beam propagation ratios (see 3.10.2) that are calculated from
beam widths and divergence angles derived from the second moments of the power (energy) density distribution
function allow calculation of beam propagation. In this document, quantities based on the second moment are
marked by a subscript “σ”.
NOTE 6 A list of symbols is given in Annex B.
© ISO 2018 – All rights reserved 1

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SIST EN ISO 11145:2019
ISO 11145:2018(E)

3.1 Beam position
3.1.1
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: The terms beam centroid, centre of gravity and beam position are equivalent, formerly the term
beam position was used.
Note 3 to entry: These quantities are defined in the beam axis system x,y,z, in which z is the direction of
propagation of the beam.
3.1.2
beam positional stability
Δ (z'), Δ (z')
x y
four times the standard deviation of the measured beam positional movement at plane z′
2
N


′′
xz −xz
() ()
∑
i
i=1 
 
′
Δ z =4
()
x
N−1
2
N
 
′′
yz − yz
() ()
∑
i
 
i=1
 
Δ z′ =4
()
y
N−1
′ ′ ′ ′
where xz and yz are the beam centroids in the z′ plane, xz and yz are the mean beam
() () () ()
centroids in the z′ plane, and N is the number of measurements
Note 1 to entry: The term "beam angular stability", sometimes referred to as “beam pointing stability”, is defined
in ISO 11670:2003.
[SOURCE: ISO 11670:2003, 3.6, modified — The note has been deleted, the text after "at plane z'" has
been added and Note 1 to entry has been added.]
3.2 Beam axis
3.2.1
beam axis
straight line connecting the centroids defined by the first spatial moments of the cross-sectional power
(energy) density distribution function at successive locations in the direction of propagation (z) of the
beam in a homogeneous medium
2 © ISO 2018 – All rights reserved

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SIST EN ISO 11145:2019
ISO 11145:2018(E)

3.2.2
misalignment angle
Δϑ
deviation angle of the beam axis from the mechanical axis defined by the manufacturer
3.3 Beam diameter
3.3.1
beam diameter
d (z)
u
diameter of a circular aperture in a plane perpendicular to the beam axis
that contains u % of the total beam power (energy)
Note 1 to entry: For clarity, the term “beam diameter” is always used in combination with the symbol and its
appropriate subscript: d or d .
u σ
3.3.2
beam diameter
d (z)
σ
diameter defined by using the second
moment of the power (energy) density distribution function
dz = 22σ z
() ()
σ
where the second moment of the power density distribution function E(x, y, z) of the beam z is given by
22
 
xx− zy+− yz ⋅Ex,,yz ⋅ddxy
() () ()
() ()
 
∫∫
 
2
σ z =
()
Ex,,yz ⋅dxddy
()
∫∫
where the first moments give the coordinates of the beam centroid xz , yz 
() ()
 
Note 1 to entry: For clarity, the term “beam diameter” is always used in combination with the symbol and its
appropriate subscript: d or d
u σ.
3.4 Beam radius
3.4.1
beam radius
w (z)
u
radius of a circular aperture in a plane perpendicular to the beam axis
which contains u % of the total beam power (energy)
Note 1 to entry: For clarity, the term “beam radius” is always used in combination with the symbol and its
appropriate subscript: w or w .
u σ
Note 2 to entry: The beam radius is half the beam diameter d (z).
u
3.4.2
beam radius
w (z)
σ
radius defined by using the second
moment of the power (energy) density distribution function
wz = 2σ z
() ()
σ
2
Note 1 to entry: For a definition of the second moment σ (z), see 3.3.2.
© ISO 2018 – All rights reserved 3

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SIST EN ISO 11145:2019
ISO 11145:2018(E)

Note 2 to entry: For clarity, the term “beam radius” is always used in combination with the symbol and its
appropriate subscript: w or w .
u σ
Note 3 to entry: The beam radius is half the beam diameter d (z).
σ
3.5 Beam width
3.5.1
beam width
d (z), d (z)
x,u y,u
width of the smallest slit aligned with the x or y transverse axes of
the power (energy) density distribution function, transmitting u % of the total beam power (energy)
along x or y
Note 1 to entry: For circular Gaussian beams, d and d both equal d .
x,95,4 y,95,4 86,5
Note 2 to entry: For clarity, the term “beam width” is always used in combination with the symbol and its
appropriate subscripts: d , d or d , d .
σx σy x,u y,u
3.5.2
beam width
d (z), d (z)
σx σy
width defined by using the second
moment of the power (energy) density distribution function along x or y
dz = 4σ z
() ()
σxx
dz = 4σ z
() ()
σ yy
where the second moments of the power density distribution function E(x, y, z) of the beam at z are
given by:
2
xx− ()zE⋅ ()xy,,zx⋅ddy
()
∫∫
2
σ z =
()
x
Ex,,yz ⋅ddxy
()
∫∫
2
yy− zE⋅ xy,,zx⋅ddy
()() ()
∫∫
2
σ z =
()
y
Ex,,yz ⋅ddxy
()
∫∫
where xx− z and yy− z are the distances from the current point’s coordinates to the beam
()() ()()
centroid xz , yz
()() ()
Note 1 to entry: For clarity, the term “beam width” is always used in combination with the symbol and its
appropriate subscripts: d , d or d , d .
σx σy x,u y,u
3.6 Beam cross-sectional area
3.6.1
beam cross-sectional area
A (z)
u
smallest completely filled area containing u % of the total beam power
(energy)
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
4 © ISO 2018 – All rights reserved

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SIST EN ISO 11145:2019
ISO 11145:2018(E)

3.6.2
beam cross-sectional area
A (z)
σ
area of a beam with circular
cross-section
 π
2
Ad= ⋅ z
()
σσ 
4
 
or elliptical cross-section
 π
Ad= ⋅ zd⋅ z
() ()
σσ  xyσ
4
 
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
3.6.3
beam ellipticity
ε(z)
parameter for quantifying the circularity or squareness of a power (energy) density 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 dd≥
σσxy
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: 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 13694.
3.6.4
circular power density distribution
power density distribution having an ellipticity greater than or equal to 0,87
3.7 Beam waist
3.7.1
beam waist
portion of a beam where the beam diameter or beam width has a local minimum
3.7.2
beam waist location
z , z , z
0x 0y 0
location where the beam widths or the beam diameters reach their minimum values along the beam axis
Note 1 to entry: A particular beam can have multiple beam waist locations.
© ISO 2018 – All rights reserved 5

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SIST EN ISO 11145:2019
ISO 11145:2018(E)

3.7.3
astigmatic beam waist separation
Δz
a
axial distance between the beam waist locations in the orthogonal principal planes of a beam possessing
simple astigmatism
Note 1 to entry: Astigmatic beam waist separation is also known as “astigmatic difference”.
[SOURCE: ISO 15367-1:2003, 3.3.4, modified — In the term, "beam" has been added.]
3.7.4
beam waist diameter
d
0,u
diameter d of the beam at the location of the beam waist
u
Note 1 to entry: For clarity, the term “beam waist diameter” is always used in combination with the symbol and
its appropriate subscripts: d or d .
0,u σ0
3.7.5
beam waist diameter
d
σ0
diameter d of the beam at the
σ
location of the beam waist
Note 1 to entry: For clarity, the term “beam waist diameter” is always used in combination with the symbol and
its appropriate subscripts: d or d .
0,u σ0
3.7.6
beam waist radius
w
0,u
radius w of the beam at the location of the beam waist, which is half the
u
beam waist diameter d
0,u
Note 1 to entry: For clarity, the term “beam waist radius” is always used in combination with the symbol and its
appropriate subscripts: w or w .
0,u σ0
3.7.7
beam waist radius
w
σ,0
radius w of the beam at the location
σ
of the beam waist, which is half the beam waist diameter d
σ0
Note 1 to entry: For clarity, the term “beam waist radius” is always used in combination with the symbol and its
appropriate subscripts: w or w .
0,u σ0
3.7.8
beam waist width
d , d
x0,u y0,u
beam width d or d at the location of the beam waist in the x or y
x,u y,u
direction, r
...