SIST EN ISO 21254-2:2011
(Main)Lasers and laser-related equipment - Test methods for laser-induced damage threshold - Part 2: Threshold determination (ISO 21254-2:2011)
Lasers and laser-related equipment - Test methods for laser-induced damage threshold - Part 2: Threshold determination (ISO 21254-2:2011)
This part of ISO 21254 describes 1-on-1 and S-on-1 tests for the determination of the laser-induced damage threshold of optical laser components. It is applicable to all types of laser and all operating conditions.
Laser und Laseranlagen - Prüfverfahren für die laserinduzierte Zerstörschwelle - Teil 2: Bestimmung der Zerstörschwelle (ISO 21254-2:2011)
Diese Norm ist ein Teil von ISO 21254 und legt die Bestimmung von 1-auf-1- und S-auf-1-laserinduzierten Zerstörschwellen optischer Laserkomponenten fest. Die Norm ist auf alle Arten von Lasern und bei allen Einsatzbedingungen anwendbar.
Lasers et équipements associés aux lasers - Méthodes d'essai du seuil d'endommagement provoqué par laser - Partie 2: Détermination du seuil (ISO 21254-2:2011)
L'ISO 21254-2:2011 définit la détermination du seuil d'endommagement 1 sur 1 et S sur 1 provoqué par un rayonnement laser sur des composants optiques pour laser. Elle s'applique à tous les types de lasers et de conditions de fonctionnement.
Laserji in z laserji povezana oprema - Ugotavljanje praga poškodbe na optični površini, povzročene z laserjem - 2. del: Določanje praga poškodbe (ISO 21254-2:2011)
Ta del ISO 21254 opisuje preskuse 1-na-1 in S-na-1 za ugotavljanje praga poškodbe na optični površini laserskih komponent, povzročene z laserjem. Velja za vse vrste laserjev in za vse pogoje delovanja.
General Information
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Standards Content (Sample)
SLOVENSKI STANDARD
SIST EN ISO 21254-2:2011
01-oktober-2011
1DGRPHãþD
SIST EN ISO 11254-1:2000
SIST EN ISO 11254-2:2002
SIST EN ISO 11254-2:2002/AC:2003
/DVHUMLLQ]ODVHUMLSRYH]DQDRSUHPD8JRWDYOMDQMHSUDJDSRãNRGEHQDRSWLþQL
SRYUãLQLSRY]URþHQH]ODVHUMHPGHO 'RORþDQMHSUDJDSRãNRGEH ,62
Lasers and laser-related equipment - Test methods for laser-induced damage threshold -
Part 2: Threshold determination (ISO 21254-2:2011)
Laser und Laseranlagen - Prüfverfahren für die laserinduzierte Zerstörschwelle - Teil 2:
Bestimmung der Zerstörschwelle (ISO 21254-2:2011)
Lasers et équipements associés aux lasers - Méthodes d'essai du seuil
d'endommagement provoqué par laser - Partie 2: Détermination du seuil (ISO 21254-
2:2011)
Ta slovenski standard je istoveten z: EN ISO 21254-2:2011
ICS:
31.260 Optoelektronika, laserska Optoelectronics. Laser
oprema equipment
SIST EN ISO 21254-2:2011 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
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SIST EN ISO 21254-2:2011
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SIST EN ISO 21254-2:2011
EUROPEAN STANDARD
EN ISO 21254-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
July 2011
ICS 31.260 Supersedes EN ISO 11254-1:2000, EN ISO 11254-2:2001
English Version
Lasers and laser-related equipment - Test methods for laser-
induced damage threshold - Part 2: Threshold determination
(ISO 21254-2:2011)
Lasers et équipements associés aux lasers - Méthodes Laser und Laseranlagen - Prüfverfahren für die
d'essai du seuil d'endommagement provoqué par laser -
laserinduzierte Zerstörschwelle - Teil 2: Bestimmung der
Partie 2: Détermination du seuil (ISO 21254-2:2011) Zerstörschwelle (ISO 21254-2:2011)
This European Standard was approved by CEN on 14 July 2011.
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, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and United Kingdom.
EUROPEAN COMMITTEE FOR STANDARDIZATION
COMITÉ EUROPÉEN DE NORMALISATION
EUROPÄISCHES KOMITEE FÜR NORMUNG
Management Centre: Avenue Marnix 17, B-1000 Brussels
© 2011 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 21254-2:2011: E
worldwide for CEN national Members.
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SIST EN ISO 21254-2:2011
EN ISO 21254-2:2011 (E)
Contents Page
Foreword .3
2
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SIST EN ISO 21254-2:2011
EN ISO 21254-2:2011 (E)
Foreword
This document (EN ISO 21254-2:2011) 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 2012, and conflicting national standards shall be withdrawn at
the latest by January 2012.
Attention is drawn to the possibility that some of the elements of this document may be the subject of patent
rights. CEN [and/or CENELEC] shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 11254-1:2000, EN ISO 11254-2:2001.
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, Romania, Slovakia, Slovenia, Spain,
Sweden, Switzerland and the United Kingdom.
Endorsement notice
The text of ISO 21254-2:2011 has been approved by CEN as a EN ISO 21254-2:2011 without any
modification.
3
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SIST EN ISO 21254-2:2011
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SIST EN ISO 21254-2:2011
INTERNATIONAL ISO
STANDARD 21254-2
First edition
2011-07-15
Lasers and laser-related equipment —
Test methods for laser-induced damage
threshold —
Part 2:
Threshold determination
Lasers et équipements associés aux lasers — Méthodes d'essai
du seuil d'endommagement provoqué par laser —
Partie 2: Détermination du seuil
Reference number
ISO 21254-2:2011(E)
©
ISO 2011
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SIST EN ISO 21254-2:2011
ISO 21254-2:2011(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2011
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means,
electronic or mechanical, including photocopying and microfilm, without permission in writing from either ISO at the address below or
ISO's member body in the country of the requester.
ISO copyright office
Case postale 56 • CH-1211 Geneva 20
Tel. + 41 22 749 01 11
Fax + 41 22 749 09 47
E-mail copyright@iso.org
Web www.iso.org
Published in Switzerland
ii © ISO 2011 – All rights reserved
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SIST EN ISO 21254-2:2011
ISO 21254-2:2011(E)
Contents Page
Foreword .iv
Introduction.v
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Test methods .1
4.1 General .1
4.2 1-on-1 test method .1
4.3 S-on-1 test method .3
5 Accuracy.7
6 Test report.7
6.1 General .7
6.2 1-on-1 test.8
6.3 S-on-1 test .8
Annex A (informative) Example of a measurement procedure (1-on-1 test).9
Annex B (informative) Example of a test report for a 1-on-1 test.15
Annex C (informative) Example of a measurement procedure (S-on-1 test) .20
Annex D (informative) Example of a test report for an S-on-1 test.24
Annex E (informative) Extrapolation method for S-on-1 tests .31
Annex F (informative) Conversion of damage data into defect densities.33
Bibliography.36
© ISO 2011 – All rights reserved iii
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SIST EN ISO 21254-2:2011
ISO 21254-2:2011(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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 21254-2 was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee SC 9,
Electro-optical systems.
This first edition of ISO 21254-2:2011, together with ISO 21254-1:2011, cancels and replaces
ISO 11254-1:2000 and ISO 11254-2:2001, which have been technically revised.
ISO 21254 consists of the following parts, under the general title Lasers and laser-related equipment — Test
methods for laser-induced damage threshold:
⎯ Part 1: Definitions and general principles
⎯ Part 2 : Threshold determination
⎯ Part 3: Assurance of laser power (energy) handling capabilities
⎯ Part 4: Inspection, detection and measurement [Technical Report]
iv © ISO 2011 – All rights reserved
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SIST EN ISO 21254-2:2011
ISO 21254-2:2011(E)
Introduction
This part of ISO 21254 specifies test methods for determining single-shot and multiple-shot laser-induced
damage thresholds (LIDTs) of optical components, both coated and uncoated. The aim is to provide methods
which will enable measurement results to be obtained which are consistent and can be rapidly and accurately
compared between different test laboratories.
In the single-shot test, which is referred to as the 1-on-1 test in this International Standard, each unexposed
site on the sample surface is subjected to only one pulse of laser radiation. Repeated laser radiation pulses
can damage optical components, or otherwise cause them to deteriorate, at irradiation levels below those
measured for single-shot damage. Besides reversible effects induced by thermal heating and distortion,
irreversible damage due to ageing, microdamage and the generation or migration of defects is observed. The
degradation of the optical quality is a function of the laser operating parameters and the optical system in
which the component is located. The multiple-shot test, referred to as the S-on-1 test, is based on a protocol
that uses a series of pulses with constant energy density at each unexposed test site.
In addition to an evaluation technique based on the survival curve for 1-on-1 tests, this part of ISO 21254 also
describes two methods for the reduction of raw data obtained from S-on-1 damage tests: one using the
characteristic damage curve and the other an extrapolation technique. The characteristic damage curve
method calls for S-on-1 testing at a large number of sites on the optical surface of the specimen and
generation of a set of three graphs indicating energy density values corresponding to probabilities of damage
of 10 %, 50 % and 90 % for a selected number of pulses. The characteristic damage curve represents the
results of a complete and extended laser-induced damage test, and it is recommended for basic investigations
in newly developed or critical laser optics. The second method of S-on-1 testing, the extrapolation method,
uses a considerably smaller number of test sites. This method generates a distribution diagram of the
damaged and undamaged regions for the behaviour of the damage threshold as a function of the number of
pulses per site. This diagram is of limited reliability but may be employed for the quality control of optical laser
components which have already been qualified by a complete damage test or as part of the preparation for
extended damage testing.
9
Realistic laser damage tests suitable for industrial applications require a large number of pulses (10 to
11
10 pulses) and hence involve a disproportionate experimental cost. This part of ISO 21254 therefore also
outlines a procedure for obtaining the S-on-1 threshold by extrapolation of the characteristic damage curve in
order to estimate the real lifetime of an optical component.
NOTE It should be realized that the laser-induced damage threshold of an optical component which is subjected to
repeated pulses of radiation can be affected by a variety of different degradation mechanisms, including contamination,
thermal heating, migration or generation of internal defects, and structural changes. These mechanisms are influenced by
the laser operating parameters, the environment and the component mounting conditions. For these reasons, it is
necessary to record all the parameters and to bear in mind that the damage behaviour might differ in tests carried out in
different operating conditions.
The test procedures described in this part of ISO 21254 are applicable to all combinations of laser
wavelengths and pulse lengths. However, comparison of laser damage threshold data can be misleading
unless the measurements have been carried out at the same wavelength, using the same pulse length and
beam diameter. Definitions and the general principles of laser-induced damage threshold measurements are
given in ISO 21254-1.
© ISO 2011 – All rights reserved v
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SIST EN ISO 21254-2:2011
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SIST EN ISO 21254-2:2011
INTERNATIONAL STANDARD ISO 21254-2:2011(E)
Lasers and laser-related equipment — Test methods
for laser-induced damage threshold —
Part 2:
Threshold determination
WARNING — The extrapolation of damage data can lead to an overestimation of the laser-induced
damage threshold. In the case of toxic materials (e.g. ZnSe, GaAs, CdTe, ThF , chalcogenides, Be,
4
Cr, Ni), this can lead to serious health hazards. See ISO 21254-1:2011, Annex A, for further comments.
1 Scope
This part of ISO 21254 describes 1-on-1 and S-on-1 tests for the determination of the laser-induced damage
threshold of optical laser components. It is applicable to all types of laser and all operating conditions.
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.
ISO 11145, Optics and photonics — Lasers and laser-related equipment — Vocabulary and symbols
ISO 21254-1:2011, Lasers and laser-related equipment — Test methods for laser-induced damage
threshold — Part 1: Definitions and general principles
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11145 and ISO 21254-1 apply.
4 Test methods
4.1 General
The general principles of laser-induced damage threshold measurements, and the apparatus and sampling
techniques used, are described in ISO 21254-1.
4.2 1-on-1 test method
4.2.1 General
In the 1-on-1 test, each unexposed site on the surface of the sample is exposed to a single laser pulse with
defined beam parameters. From the experimental data, a plot depicting the probability of damage as a
function of the energy density or power density is constructed.
© ISO 2011 – All rights reserved 1
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SIST EN ISO 21254-2:2011
ISO 21254-2:2011(E)
4.2.2 Test parameters
The test equipment shall be characterized by the parameters described in ISO 21254-1:2011, 6.2.6.5.
4.2.3 Procedure
Test sites are positioned in the beam and irradiated by single shots of laser radiation with different energy
densities or power densities. Expose a minimum of ten sites to one preselected pulse energy (or beam power)
and record, for each site, the actual pulse energy (or beam power) measured by the beam diagnostic unit as
well as the state of damage after irradiation (damage or no damage). Repeat this sequence for other pulse
energies or beam powers. The range of pulse energies or beam powers employed shall be sufficiently broad
to include low values which result in no damage at any site and sufficiently high values which induce damage
at each site tested.
4.2.4 Evaluation of measurements
Damage threshold data are obtained by the damage-probability method. To construct a plot of the probability
of damage versus the quantity in terms of which the laser-induced damage threshold is to be expressed, the
probability of damage is determined for each energy-density or power-density increment by calculating the
ratio of the number of damaged sites to the total number of sites tested. Linear extrapolation of the damage-
probability data to zero damage probability yields the threshold value. An example is shown in Figure 1.
Key
X energy, in millijoules
Y damage probability
NOTE The test conditions were as follows: d = 1,44 mm, λ = 10,6 µm, τ = 100 ns, tail 3,5 µs (TEA CO laser),
86,5 H 2
specimens: KBr windows, 50 items, diameter 40 mm.
Figure 1 — Graph for the determination of the damage threshold from experimental data
2 © ISO 2011 – All rights reserved
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SIST EN ISO 21254-2:2011
ISO 21254-2:2011(E)
In the case of a laser system with a high pulse-to-pulse energy variation, it is permissible to expose the
specimen to arbitrary pulse energies and to sort the data with respect to appropriate energy intervals after the
test.
NOTE 1 Examples of an efficient measurement procedure giving maximum accuracy for a given number of sites are
presented in Annex A and Annex C for the 1-on-1 and the S-on-1 test, respectively.
NOTE 2 The diameter of the test beam at the specimen position can influence the measurement result. Therefore, the
beam diameter has to be kept constant throughout the entire measurement procedure.
4.3 S-on-1 test method
4.3.1 General
To determine the S-on-1 damage threshold, extensions of the set-up and procedure for 1-on-1 test damage
threshold measurement are necessary. However, a measurement facility for S-on-1 tests can be used for
1-on-1 measurements if the online damage-detection system is combined with a Nomarski-type differential
interference contrast microscope. It is recommended that the online damage-detection system have a facility
for cutting off subsequent pulses and for stopping the pulse counter.
4.3.2 Test parameters
The test equipment shall be characterized by the parameters described in ISO 21254-1:2011, 6.2.6.5, and the
following additional parameters:
a) number of pulses per site S;
b) total number of sites per test N .
ts
NOTE For the S-on-1 test, the parameters given in ISO 21254-1:2011, 6.2.6.5 d) to g), refer to the properties of the
typical pulse defined in ISO 21254-1:2011, 6.2.6.4.
4.3.3 Procedure
An unexposed test site is positioned in the beam and irradiated by a series of S pulses, the pulse typical of the
series having an energy Q . If damage is observed by the online damage detection system before the series
tp
of S pulses is completed, stop the irradiation of the site and record the minimum number of pulses N .
min
Repeat this procedure for different energies of the typical pulse. The number of pulses S shall be constant for
the entire test procedure, and it shall be selected such that the S-on-1 test records the specific laser-induced
damage behaviour of the specimen.
4.3.4 Evaluation of measurements
4.3.4.1 General
After inspecting the specimen, the result of the S-on-1 test described above is a file of data points of the type
(Q , N ), where N u S in the case of damage,
tp min min
(Q , S) when no damage is detected
tp
The evaluation of the data obtained (see Figure 2) may be performed using the characteristic damage curve
(see 4.3.4.2) or the extrapolation method (see 4.3.4.3). The method using the characteristic damage curve
allows accurate determination of the laser-induced damage threshold. This accurate technique should be
used for fundamental investigations and for the testing of prototype components. The extrapolation method,
on the other hand, is a practical technique for estimating the S-on-1 threshold for a large number of pulses.
© ISO 2011 – All rights reserved 3
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SIST EN ISO 21254-2:2011
ISO 21254-2:2011(E)
4.3.4.2 Characteristic damage curve
The procedure for determining the S-on-1 damage threshold (see 4.3.3) is carried out and the resulting file of
data points is recorded. For the evaluation to have sufficient significance, a minimum number N of sites
ms
shall be tested for each energy value Q of the typical pulse. This minimum number of sites N can be
tp ms
approximated by the following relationship:
N = 5 × integral value of (1 + log S) (1)
ms 10
The range of typical-pulse energies Q employed shall be sufficiently broad to include points corresponding to
tp
zero probability of damage as well as points corresponding to 100 % probability of damage.
Damage-probability values for a defined number N of pulses and a specified energy Q are calculated on the
basis of the following data-reduction technique.
The energy scale is divided into a series of intervals [Q − ∆Q, Q + ∆Q) covering the energy range accessible
with the experimental set-up. For the calculation of the damage probability for a certain energy Q and for a
selected number N of pulses, data points with Q = [Q − ∆Q, Q + ∆Q) are selected from the file of data points.
tp
Data points with N u N correspond to sites which are damaged, whereas data points with N > N or S W N
min min
correspond to sites not damaged in the energy interval considered. The damage probability for the energy Q is
calculated as the ratio of the number of data points corresponding to damaged sites to the total number of
data points considered in the evaluation.
NOTE 1 The value of ∆Q has to be chosen such that a significant fraction of data points is available for a distinct interval
[Q − ∆Q, Q + ∆Q). The value of ∆Q is kept constant during the evaluation procedure, and it determines the statistical error
of the threshold values. An example of an efficient measurement procedure with suitably selected parameters is given in
Annex C.
This procedure is repeated for other values of the energy Q to generate a data set of damage-probability
values for the selected number N of pulses. The resulting data set represents discrete points on a damage-
probability curve which is plotted versus the energy of the typical pulse. From this curve, the energy values
Q , Q and Q for the corresponding damage-probability values of 10 %, 50 % and 90 % are deduced by
10 50 90
extrapolation.
Linear extrapolation of the damage-probability curve to zero damage probability yields the threshold energy
(see 4.2.4) which shall be converted into units of threshold energy density H or threshold power density E .
th th
Linear extrapolation using the two data points next to the targeted damage probability is sufficient. If a large
number of data points are available, more sophisticated extrapolation methods are permitted. The
extrapolation procedure used shall be stated in the test report.
In Figure 2, data points corresponding to damaged spots are represented by and those corresponding to
undamaged spots are represented by o. The evaluation procedure used for the damage-probability method is
illustrated by the interval [Q − ∆Q, Q + ∆Q) marked on the graph. More than one point can occur for a specific
data pair (Q , S) or (Q , N ) during the test. The number of points for a specific data pair may be indicated
tp tp min
on the graph.
Figure 2 is an illustrative representation of a typical data set obtained in an S-on-1 laser-induced damage
threshold (LIDT) test. Therefore, the pulse energy scale is given in arbitrary units, and no numbers are given
to indicate the presence of identical data points.
4 © ISO 2011 – All rights reserved
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SIST EN ISO 21254-2:2011
ISO 21254-2:2011(E)
Key
X number of pulses
Y pulse energy, in millijoules
1 undamaged
2 damaged
Figure 2 — Data points resulting from damage testing
To generate the characteristic damage curve, the algorithm described above is repeated for selected numbers
N of pulses to determine the corresponding energy values Q , Q , and Q . These values are converted into
10 50 90
the units in which the damage threshold is expressed and plotted versus the number of pulses. The numbers
of pulses shall be selected in a way that at least five data points are located in the significant region of the
characteristic damage curve. Log-log coordinates are recommended for this plot to make it possible to carry
out a linear extrapolation of the characteristic damage curve for large numbers of pulses (see Figure 3).
NOTE 2 Log-log coordinates might not be appropriate for an extrapolation of the characteristic damage curve for
extremely large numbers of pulses. In many cases, the characteristic damage curve converges to a finite energy density,
and the shape of this convergence might give information on the laser-induced ageing mechanisms involved (see
Annex E).
4.3.4.3 Extrapolation method
A distribution diagram of damaged and undamaged regions can be generated on the basis of a test with a
reduced number of data points. In the extrapolation method, S-on-1 test procedures are performed covering a
range of numbers of pulses per test site that is appropriate for determining, by extrapolation, the S-on-1
damage threshold for a defined large number of pulses. A slightly modified test procedure (see 4.3.3) is
performed for a selected set of data points. In this method, the number of pulses S is varied during the test
procedure, and it shall be selected such that a significant number of sites are irradiated with the selected
number of pulses S. The irradiation of an individual test site is stopped after the defined number of pulses has
been reached or damage has been detected. The result of this irradiation protocol is a set of data points (Q ,
tp
S, state of damage) represented by the energy of the typical pulse, the selected number of pulses, and the
state of damage, respectively. For specimens which show self-quenching damage mechanisms, the
extrapolation method can also be used in damage-testing facilities without an online damage detection system.
In this case, each site is subjected to the selected number of pulses independently of the state of damage.
© ISO 2011 – All rights reserved 5
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SIST EN ISO 21254-2:2011
ISO 21254-2:2011(E)
Key
X number of pulses
Y energy density, in joules per square centimetre
1 90 % LIDT
2 50 % LIDT
3 10 % LIDT
NOTE The test conditions were as follows: τ = 130 fs, d = 87 µm, λ = 780 nm, f = 1 kHz, specimen: HR mirror
eff T,eff p
(Ta O /SiO ) for 780 nm.
2 5 2
Figure 3 — Characteristic damage curve
For each data point, the energy value Q is converted into the unit of energy density or power density and
tp
plotted as a graph presenting this value versus the number of pulses. By separating the data points with
respect to the state of damage, the damaged and undamaged regions are indicated by the graph. This
distribution diagram (see Figure 4) makes it possible to give an appro
...
SLOVENSKI STANDARD
oSIST prEN ISO 21254-2:2009
01-marec-2009
/DVHUMLLQ]ODVHUMLSRYH]DQDRSUHPD8JRWDYOMDQMHSUDJDSRãNRGEHQDRSWLþQL
SRYUãLQLSRY]URþHQH]ODVHUMHPGHO 'RORþDQMHSUDJDSRãNRGEH ,62',6
Lasers and laser-related equipment - Test methods of laser radiation-induced damage
threshold - Part 2: Threshold determination (ISO/DIS 21254-2:2008)
Laser und Laseranlagen - Prüfverfahren für die laserstrahlungsinduzierte
Zerstörschwelle - Teil 2: Bestimmung der Zerstörschwelle (ISO/DIS 21254-2:2008)
Lasers et équipements associés aux lasers - Méthodes d'essai pour seuil
d'endommagement provoqué par laser - Partie 2: Détermination du seuil (ISO/DIS 21254
-2:2008)
Ta slovenski standard je istoveten z: prEN ISO 21254-2
ICS:
31.260 Optoelektronika, laserska Optoelectronics. Laser
oprema equipment
oSIST prEN ISO 21254-2:2009 en
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.
---------------------- Page: 1 ----------------------
oSIST prEN ISO 21254-2:2009
---------------------- Page: 2 ----------------------
oSIST prEN ISO 21254-2:2009
EUROPEAN STANDARD
DRAFT
prEN ISO 21254-2
NORME EUROPÉENNE
EUROPÄISCHE NORM
November 2008
ICS 31.260 Will supersede EN ISO 11254-1:2000, EN ISO 11254-
2:2001
English Version
Lasers and laser-related equipment - Test methods of laser
radiation-induced damage threshold - Part 2: Threshold
determination (ISO/DIS 21254-2:2008)
Lasers et équipements associés aux lasers - Méthodes Laser und Laseranlagen - Prüfverfahren für die
d'essai pour seuil d'endommagement provoqué par laser - laserstrahlungsinduzierte Zerstörschwelle - Teil 2:
Partie 2: Détermination du seuil (ISO/DIS 21254-2:2008) Bestimmung der Zerstörschwelle (ISO/DIS 21254-2:2008)
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© 2008 CEN All rights of exploitation in any form and by any means reserved Ref. No. prEN ISO 21254-2:2008: E
worldwide for CEN national Members.
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oSIST prEN ISO 21254-2:2009
prEN ISO 21254-2:2008
Contents Page
Foreword .3
2
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oSIST prEN ISO 21254-2:2009
prEN ISO 21254-2:2008
Foreword
This document (prEN ISO 21254-2:2008) has been prepared by Technical Committee ISO/TC 172 "Optics
and optical instruments" in collaboration with Technical Committee CEN/TC 123 “Lasers and photonics” the
secretariat of which is held by DIN.
This document is currently submitted to the parallel Enquiry.
This document will supersede EN ISO 11254-1:2000, EN ISO 11254-2:2001.
Endorsement notice
The text of ISO/DIS 21254-2:2008 has been approved by CEN as a prEN ISO 21254-2:2008 without any
modification.
3
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oSIST prEN ISO 21254-2:2009
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oSIST prEN ISO 21254-2:2009
DRAFT INTERNATIONAL STANDARD ISO/DIS 21254-2
ISO/TC 172/SC 9 Secretariat: DIN
Voting begins on: Voting terminates on:
2008-10-16 2009-03-16
INTERNATIONAL ORGANIZATION FOR STANDARDIZATION • МЕЖДУНАРОДНАЯ ОРГАНИЗАЦИЯ ПО СТАНДАРТИЗАЦИИ • ORGANISATION INTERNATIONALE DE NORMALISATION
Lasers and laser-related equipment — Test methods for laser
radiation-induced damage threshold —
Part 2:
Threshold determination
Lasers et équipements associés aux lasers — Méthodes d'essai pour seuil d'endommagement provoqué par
laser —
Partie 2: Détermination du seuil
(Revision of ISO 11254-1:2000 and ISO 11254-2:2001)
ICS 31.260
ISO/CEN PARALLEL ENQUIRY
The CEN Secretary-General has advised the ISO Secretary-General that this ISO/DIS covers a subject
of interest to European standardization. In accordance with the ISO-lead mode of collaboration as
defined in the Vienna Agreement, consultation on this ISO/DIS has the same effect for CEN
members as would a CEN enquiry on a draft European Standard. Should this draft be accepted, a
final draft, established on the basis of comments received, will be submitted to a parallel two-month FDIS
vote in ISO and formal vote in CEN.
In accordance with the provisions of Council Resolution 15/1993 this document is circulated in
the English language only.
Conformément aux dispositions de la Résolution du Conseil 15/1993, ce document est distribué
en version anglaise seulement.
To expedite distribution, this document is circulated as received from the committee secretariat.
ISO Central Secretariat work of editing and text composition will be undertaken at publication
stage.
Pour accélérer la distribution, le présent document est distribué tel qu'il est parvenu du
secrétariat du comité. Le travail de rédaction et de composition de texte sera effectué au
Secrétariat central de l'ISO au stade de publication.
THIS DOCUMENT IS A DRAFT CIRCULATED FOR COMMENT AND APPROVAL. IT IS THEREFORE SUBJECT TO CHANGE AND MAY NOT BE
REFERRED TO AS AN INTERNATIONAL STANDARD UNTIL PUBLISHED AS SUCH.
IN ADDITION TO THEIR EVALUATION AS BEING ACCEPTABLE FOR INDUSTRIAL, TECHNOLOGICAL, COMMERCIAL AND USER PURPOSES, DRAFT
INTERNATIONAL STANDARDS MAY ON OCCASION HAVE TO BE CONSIDERED IN THE LIGHT OF THEIR POTENTIAL TO BECOME STANDARDS TO
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RECIPIENTS OF THIS DRAFT ARE INVITED TO SUBMIT, WITH THEIR COMMENTS, NOTIFICATION OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPORTING DOCUMENTATION.
©
International Organization for Standardization, 2008
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oSIST prEN ISO 21254-2:2009
ISO/DIS 21254-2
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ii ISO 2008 – All rights reserved
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oSIST prEN ISO 21254-2:2009
ISO/DIS 21254-2
Contents Page
1 Scope.1
2 Normative references.1
3 Terms and definitions .1
4 Test methods .2
4.1 Test method 1 on 1 test .2
4.1.1 Test parameters 1 on 1 test.2
4.1.2 Procedure 1 on 1 test.2
4.1.3 Evaluation 1 on 1 test.2
4.2 Test method S on 1 test.3
4.2.1 Test parameters S on 1 test .3
4.2.2 Procedure S on 1 test.3
4.2.3 Evaluation S on 1 test .4
5 Accuracy .7
6 Test report.7
6.1 1 on1 test.7
6.2 S on1 test .8
Annex A (informative) Example of a measurement procedure.9
Annex B (informative) Test report example.15
Annex C (informative) Example of a measurement procedure.19
Annex D (informative) Example of test report.23
Annex E (informative) Extrapolation method for S-on-1 tests.27
Annex F (informative) Conversion of damage data into defect density .29
© ISO 2008 – All rights reserved iii
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oSIST prEN ISO 21254-2:2009
ISO/DIS 21254-2
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.
International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.
The main task of technical committees is to prepare International Standards. Draft International Standards
adopted by the technical committees are circulated to the member bodies for voting. Publication as an
International Standard requires approval by at least 75 % of the member bodies casting a vote.
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.
ISO 21254-2 was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee SC 9,
Electro-optical systems and by Technical Committee CEN/TC 123, Lasers and photonics in collaboration.
This second edition cancels and replaces the first editions (ISO 11254-1:2000, ISO 11254-2:2001 and ISO
11254-3:2006), which have been technically revised.
ISO 21254 consists of the following parts, under the general title Lasers and laser-related equipment — Test
methods for laser radiation-induced damage threshold:
⎯ Part 1: Definitions and general principles;
⎯ Part 2 : Threshold determination;
⎯ Part 3: Assurance of laser power (energy) handling capabilities;
⎯ Part 4: Inspection, detection and measurement (Technical Report).
Annexes A to F are for information only.
iv © ISO 2008 – All rights reserved
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oSIST prEN ISO 21254-2:2009
ISO/DIS 21254-2
Introduction
This part of ISO 21254 specifies test methods for determining single-shot and multiple-shot laser radiation-
induced damage thresholds (LIDT) of optical components, both coated and uncoated. The procedures have
been promulgated in order to provide a method for obtaining consistent measurement results, which may be
rapidly and accurately compared among different testing laboratories.
In the single-shot test, which is assigned to the term 1 on 1 test within this standard, each unexposed site of
the sample surface is subjected to only one pulse of laser radiation. Repetitive laser radiation may deteriorate
and damage optical components at irradiation levels below those measured for single shot damage. Besides
reversible mechanisms induced by thermal heating and distortion, irreversible damage mechanisms due to
ageing, microdamage and generation or migration of defects are observed. The degradation of the optical
quality is a function of the laser operating parameters and the optical system in which the component is
placed. The multiple-shot test, S on 1 test, is based on a protocol that uses a series of pulses with constant
energy density on each unexposed test site.
Besides an evaluation technique based on the survival curve for 1 on 1 tests, this standard also describes two
evaluation methods for the reduction of raw data of S on 1 damage tests: the characteristic damage curve and
the extrapolation method. The characteristic damage curve method is based on a large number of S on 1 test
sites on the optical surface of the specimen and comprises a set of three graphs indicating energy density
values with damage probability values of 10 %, 50 % and 90 % for a selected number of pulses. The
characteristic damage curve represents the results of a complete and extended laser induced damage test,
and it is recommended for basic investigations in newly developed or critical laser optics. The second
evaluation technique for S on 1 tests, the extrapolation method, is created from a considerably smaller
number of test sites. This method generates a distribution diagram of damage and non-damage regions for
the behaviour of the damage threshold as a function of the number of pulses per site. This diagram is of
limited reliability and may be employed for the quality control of optical laser components, which are already
qualified by a complete damage test, or for the preparation of extended damage testing.
Realistic laser damage tests adapted to industrial applications are dependent on a large number of pulses
9 11
(10 to 10 pulses) and require a disproportionate experimental expense. This standard therefore outlines
also a procedure for an extrapolation of the S on 1 threshold from the characteristic damage curve to estimate
the real lifetime of an optical component.
NOTE It must be realised that the laser induced damage threshold of an optical component which is subjected to
repetitive radiation can be affected by a variety of different degradation mechanisms including contamination, thermal
heating, migration or generation of internal defects and structural changes. These mechanisms are influenced by the laser
operating parameters, the environment and the mounting conditions of the component under test. For these reasons it is
necessary to record all parameters and to realise that the damage behaviour may differ in systems with altered operating
conditions.
The test procedures described in this standard are applicable to all combinations of different laser
wavelengths and pulse lengths. However comparison of laser damage threshold data may be misleading
unless the measurements have been carried out at identical wavelengths, pulse lengths and beam diameters.
Definitions and the general principle of laser induced damage threshold measurements are described in
ISO/DIS 21254-1:2008.
Safety Warning: The extrapolation of damage data may lead to bad or erroneous calculated results and to an
overestimation of the LIDT. This may in the cases of toxic materials (e.g. ZnSe, GaAs, CdTe, ThF ,
4
chalcogenides, Be, Cr, Ni) lead to severe health hazards. See ISO/DIS 21254-1:2008, Annex A for further
comments.
© ISO 2008 – All rights reserved v
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oSIST prEN ISO 21254-2:2009
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oSIST prEN ISO 21254-2:2009
DRAFT INTERNATIONAL STANDARD ISO/DIS 21254-2
Lasers and laser-related equipment — Test methods for laser
radiation-induced damage threshold —
Part 2:
Threshold determination
1 Scope
This standard is part of ISO 21254 and defines the determination of 1 on 1 and S on 1 laser radiation induced
damage thresholds of optical laser components. The standard is applicable to all types of lasers and operation
conditions.
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.
ISO 10110-7:1996, Optics and optical instruments — Preparation of drawings for optical elements and
systems — Part 7: Surface imperfection tolerances.
ISO 11145, Optics and photonics — Lasers and laser-related equipment — Vocabulary and symbols.
ISO 15367-1, Lasers and laser-related equipment — Test methods for determination of the shape of a laser
beam wavefront — Part 1: Terminology and fundamental aspects
ISO 15367-2, Lasers and laser-related equipment — Test methods for determination of the shape of a laser
beam wavefront — Part 2: Shack-Hartmann sensors
ISO/DIS 21254-1:2008, Lasers and laser-related equipment — Test method for laser radiation-induced
damage threshold — Part 1: Definitions and general principles.
1)
ISO/TR 21254-4: , Lasers and laser-related equipment — Test method for laser radiation-induced damage
threshold — Part 4: Inspection, detection and measurement.
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11145 and ISO/DIS 21254-1:2008
apply.
1) To be published.
1
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oSIST prEN ISO 21254-2:2009
ISO/DIS 21254-2
4 Test methods
The apparatus, general principle and sampling for laser induced damage threshold measurements are
described in ISO/DIS 21254-1:2008.
4.1 Test method 1 on 1 test
In the 1 on 1 test each unexposed site on the surface of the sample is interrogated by a single laser pulse with
defined beam parameters. From the experimental data a diagram depicting the damage probability as a
function of the energy density or power density is deduced.
4.1.1 Test parameters 1 on 1 test
The testing equipment shall be characterised by the parameters described in ISO/DIS 21254-1:2008, 6.2.6.5
a) – h).
4.1.2 Procedure 1 on 1 test
Test sites are positioned into the beam and irradiated by single shots of laser radiation with different energy
densities or power densities. Expose a minimum of ten sites to one preselected pulse energy (or beam power)
and record the actual pulse energy (or beam power) measured by the beam diagnostic unit as well as the
state of damage after irradiation (damage or no damage) for each site. Repeat this sequence for other pulse
energies or beam powers. The range of pulse energies or beam powers employed shall be sufficiently broad
to include low values with no damage for any site and sufficiently high values which induce damage for each
site tested in the sequence.
4.1.3 Evaluation 1 on 1 test
Damage threshold data are obtained by the damage-probability method. To develop a plot of damage
probability versus the corresponding unit of laser induced damage threshold, the probability of damage is
determined for each energy-density or power-density increment by calculating the ratio of the number of
damaged sites to the total number of sites tested. Linear extrapolation of the damage probability data to zero
damage probability yields the threshold value. An example is shown in Figure 1.
In the case of a laser system with a high pulse-to-pulse energy variation, it is permissible to expose the
specimen to arbitrary pulse energies and to sort the data with respect to appropriate energy intervals after the
experiment.
NOTE 1 For an efficient measurement procedure with maximum accuracy for a given number of sites, appropriate
examples are described in Annex A and Annex C for a 1 on 1 and S on 1 test, respectively.
NOTE 2 The diameter of the test beam at the sample position may influence the measurement result. Therefore, the
beam diameter has to be kept constant throughout the entire measurement procedure.
2
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oSIST prEN ISO 21254-2:2009
ISO/DIS 21254-2
Key
2
x energy [mJ] 1/e = 1,44 mm
y damage probability
Figure 1 — Diagram for the determination of the damage threshold from experimental data
(damage to KBr windows, 50 pieces, ∅ 40 mm, BMFT 315-5691 ATT 2249 A/8)
4.2 Test method S on 1 test
For determining the S on 1 damage threshold, extensions of the set-up and the evaluation procedure for
1 on 1 damage thresholds measurements are necessary. However, a measurement facility for S on 1 tests
can be applied for 1 on 1 measurements if the online damage detection system is combined with a Nomarski-
type differential interference contrast microscope. It is recommended that the online damage detection system
should have the facility for cutting off subsequent pulses and for stopping the pulse counter.
4.2.1 Test parameters S on 1 test
The testing equipment shall be characterised by the parameters described in ISO/DIS 21254-1:2008, 6.2.6.5
and the following parameters:
number of pulses per site N ;
p
a)
b) total number of sites per test N .
TS
NOTE For the S on 1 Test, the parameters given in ISO/DIS 21254-1:2008, 6.2.6.5 d) to g) refer to the properties of
the typical pulse defined in ISO/DIS 21254-1:2008, 6.2.6.4.
4.2.2 Procedure S on 1 test
An unexposed test site is positioned into the beam and irradiated by a series of N pulses with a selected
p
energy Q of the typical pulse. If damage is observed by the online damage detection system before the
tp
series of N pulses is completed, the irradiation of the site shall be stopped and the minimum number of
p
pulses N shall be recorded. This procedure is repeated for different energy densities of the typical pulse.
min
The number of pulses N shall be constant for the entire test procedure, and it shall be selected such that the
p
specific laser induced damage behaviour of the specimen is registered by the S on 1 test.
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oSIST prEN ISO 21254-2:2009
ISO/DIS 21254-2
4.2.3 Evaluation S on 1 test
After the inspection by the microscope technique described in ISO/TR 21254-4, the result of the described
S on 1 test program is a file of data points of the type
(Q , N ) N ≤ N in case of damage
tp min min p
(Q , N ) in case of no detectable damage
tp p
The evaluation of the data obtained (see Figure 2) may be performed by using the characteristic damage
curve (see 4.2.3.1) or the extrapolation method (see 4.2.3.2). The method of the characteristic damage curve
allows for a precise determination of the laser induced damage threshold on the basis of an experimental
7
procedure that is practicable only for numbers N of shots below 10 per site. Besides this accurate technique
p
which should be used for fundamental investigations and for testing of prototype components, the
extrapolation method is a practical technique to estimate the S on 1 threshold for a large number of pulses.
4.2.3.1 Characteristic damage curve
The procedure for the S on 1 damage threshold (see 4.2.2) is applied and the resulting file of data points is
recorded. For an evaluation with sufficient significance, a minimum number N of sites shall be tested for
ms
each energy value Q of the typical pulse. This minimum number of sites N can be approximated by the
tp ms
relation
N =5∗int(1+log(N )) . (1)
ms p
The range of typical pulse energies Q employed must be sufficiently broad to include points of zero damage
tp
probability as well as points of 100 % damage probability.
Damage probability values for a defined number N of pulses and specified energy value Q are calculated on
the basis of the following data reduction technique:
The energy scale is divided into a series of intervals [Q-∆Q,Q+∆Q) covering the energy range accessible by
the experimental set up. For the calculation of damage probability for a certain energy value Q and for a
selected number N of pulses, data points with Q ∈ [Q-∆Q,Q+∆Q) are selected from the file of data points. Data
tp
points with N ≤ N correspond to sites damaged, whereas data points with N > N or N ≥ N correspond to
min min p
sites not damaged in the considered energy interval. The damage probability for the energy Q is calculated by
the ratio of the number of data points corresponding to damaged sites with respect to the total number of data
points considered for the evaluation.
NOTE 1 The value of ∆Q has to be chosen such that a significant fraction of data points is available for a distinct interval
[Q-∆Q,Q+∆Q). The value ∆Q is kept constant during the evaluation procedure, and it determines the statistical error of the
threshold values. An example for an efficient measurement procedure and an adapted selection of the parameters is given
in Annex C.
This procedure is repeated for other energy values Q to generate a data set of damage probability values for
the selected number N of pulses. The resulting data set represents discrete points of a damage probability
curve which is plotted versus the energy of the typical pulse. From this curve, energy values Q , Q , and Q
10 50 90
are deduced for the corresponding damage probability values of 10 %, 50 %, and 90 % by extrapolation.
Linear extrapolation of the damage probability curve to zero damage probability yields the threshold energy
(see 4.1.3) which shall be converted into units of threshold energy density H or threshold power density E .
th th
NOTE 2 A linear extrapolation involving the two data points next to the targeted damage probability is sufficient. If an
experimental basis with a large number of data points is available, more sophisticated extrapolation methods are
permitted. The extrapolation procedure should be documented in the test report.
4
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oSIST prEN ISO 21254-2:2009
ISO/DIS 21254-2
Key
x number of pulses undamaged
y pulse energy [mJ] damaged
NOTE 3 Data points corresponding to damaged spots are represented by x. Undamaged spots are represented by o.
The evaluation procedure for the damage probability method is illustrated by the interval [Q-∆Q,Q+∆Q) marked in the
diagram. More than one point may occur for a specific data pair (Q , N ) or (Q , N ) during the experiment. The number
tp p tp min
of points for a specific data pair may be indi
...
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