EN ISO 13696:2022

SLOVENSKI STANDARD
01-september-2022
Nadomešča:
SIST EN ISO 13696:2002
Optika in optični instrumenti - Preskusne metode za sevanje, razpršeno z
optičnimi komponentami (ISO 13696:2022)
Optics and photonics - Test method for total scattering by optical components (ISO
13696:2022)
Optik und Photonik - Bestimmung von totaler Streustrahlung, hervorgerufen durch
optische Komponenten (ISO 13696:2022)
Optique et photonique - Méthodes d’essai du rayonnement diffusé par les composants
optiques (ISO 13696:2022)
Ta slovenski standard je istoveten z: EN ISO 13696:2022
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 13696
EUROPEAN STANDARD
NORME EUROPÉENNE
June 2022
EUROPÄISCHE NORM
ICS 31.260 Supersedes EN ISO 13696:2002
English Version
Optics and photonics - Test method for total scattering by
optical components (ISO 13696:2022)
Optique et photonique - Méthodes d'essai du Optik und Photonik - Bestimmung von totaler
rayonnement diffusé par les composants optiques (ISO Streustrahlung, hervorgerufen durch optische
13696:2022) Komponenten (ISO 13696:2022)
This European Standard was approved by CEN on 21 May 2022.

CEN members are bound to comply with the CEN/CENELEC Internal Regulations which stipulate the conditions for giving this
European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references
concerning such national standards may be obtained on application to the CEN-CENELEC Management Centre or to any CEN
member.
This European Standard exists in three official versions (English, French, German). A version in any other language made by
translation under the responsibility of a CEN member into its own language and notified to the CEN-CENELEC Management
Centre has the same status as the official versions.

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

EUROPÄISCHES KOMITEE FÜR NORMUNG

CEN-CENELEC Management Centre: Rue de la Science 23, B-1040 Brussels
© 2022 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 13696:2022 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 13696:2022) has been prepared by Technical Committee ISO/TC 172 "Optics
and photonics" in collaboration with Technical Committee CEN/TC 123 “Lasers and photonics” the
secretariat of which is held by DIN.
This European Standard shall be given the status of a national standard, either by publication of an
identical text or by endorsement, at the latest by December 2022, and conflicting national standards
shall be withdrawn at the latest by December 2022.
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. CEN shall not be held responsible for identifying any or all such patent rights.
This document supersedes EN ISO 13696:2002.
Any feedback and questions on this document should be directed to the users’ national standards
body/national committee. A complete listing of these bodies can be found on the CEN website.
According to the CEN-CENELEC Internal Regulations, the national standards organizations of the
following countries are bound to implement this European Standard: Austria, Belgium, Bulgaria,
Croatia, Cyprus, Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland,
Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, Netherlands, Norway, Poland, Portugal, Republic of
North Macedonia, Romania, Serbia, Slovakia, Slovenia, Spain, Sweden, Switzerland, Turkey and the
United Kingdom.
Endorsement notice
The text of ISO 13696:2022 has been approved by CEN as EN ISO 13696:2022 without any modification.

INTERNATIONAL ISO
STANDARD 13696
Second edition
2022-06
Optics and photonics — Test method
for total scattering by optical
components
Optique et photonique — Méthodes d'essai du rayonnement diffusé
par les composants optiques
Reference number
ISO 13696:2022(E)
ISO 13696:2022(E)
© ISO 2022
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO 13696:2022(E)
Contents Page
Foreword .iv
Introduction . vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
3.1 Terms and definitions . 1
3.2 Symbols and units of measure . . 3
4 Test method . 3
4.1 Principle . 3
4.2 Measurement arrangement and test equipment . 3
4.2.1 General . 3
4.2.2 Radiation source . 4
4.2.3 Beam preparation system . 4
4.2.4 Integrating sphere . 5
4.2.5 Detection system. 6
4.2.6 Specimen holder . 6
4.3 Arrangement with high sensitivity . 6
4.4 Preparation of specimens . 7
5 Procedure .7
5.1 General . 7
5.2 Alignment procedure . 8
5.2.1 General . 8
5.2.2 Alignment of the beam . 8
5.2.3 Alignment of the specimen . 8
5.3 Measurement procedure . 8
6 Evaluation . 9
6.1 Determination of the total scattering value . 9
6.2 Error budget .12
7 Test report .12
Annex A (informative) Set-up with a Coblentz hemisphere .14
Annex B (informative) Example of test report .17
Annex C (informative) Statistical evaluation example .21
Annex D (informative) Example for selection of spacing .26
Annex E (informative) Alternative method for calibrating total scatter measurements
using a calcium fluoride diffuser disk .29
Bibliography .31
iii
ISO 13696:2022(E)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out
through ISO technical committees. Each member body interested in a subject for which a technical
committee has been established has the right to be represented on that committee. International
organizations, governmental and non-governmental, in liaison with ISO, also take part in the work.
ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of
electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are
described in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the
different types of ISO documents should be noted. This document was drafted in accordance with the
editorial rules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives).
Attention is drawn to the possibility that some of the elements of this document may be the subject of
patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of
any patent rights identified during the development of the document will be in the Introduction and/or
on the ISO list of patent declarations received (see www.iso.org/patents).
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to
the World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 172, Optics and Photonics, Subcommittee
SC 9, Laser and electro-optical systems, in collaboration with the European Committee for Standardization
(CEN) Technical Committee CEN/TC 123, Lasers and photonics, in accordance with the agreement on
technical cooperation between ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 13696:2002), which has been technically
revised.
The main changes are as follows:
— In the Scope, measurement range outlined in more detail and limited to 250 nm. For measurements in
the deep ultraviolet between 190 nm to 250 nm, specific methods are considered and are described.
— In 3.1.6, additional Note 2 inserted for high volume scattering of the specimen and additional Note
3 inserted for comprehensive illustration of the term total scattering.
— In 3.1.7, Note extended concerning diffuse reflectance standard for wavelengths below 250 nm
down to the deep ultraviolet.
— In 3.2, New symbols for total scattering, σ , forward scattering, τ , and backward scattering, ρ ,
TS TS TS
in Table 1.
— In Figure 1 and 4.2.5, lock-in amplifier optional. For fast data acquisition modules, no Lock-in
technique may be necessary.
— In 4.2.2, calibration of the monitor detector is not necessary. The power at the sample surface shall
be measured by a calibrated detector.
— In 4.2.4, additional Note 1 inserted concerning aging of the diffuse reflecting material on the inner
walls of the sphere.
— In 4.2.5, additional Note inserted concerning optional components for a phase sensitive detection
scheme with lock-in amplifier.
iv
ISO 13696:2022(E)
— In 5.3, change of measurement sequence starting with power measurement calibration procedure,
and determination of the signal of the unloaded sphere prior to the measurement of the specimen.
— In 6.1, adaptation of Formulae (1) (2) and (5) to (8) (in the denominator V ()r was adapted to V ).
ci
c
— Correction of Formula (C.2).
— Annex E inserted concerning alternative method for calibrating total scatter measurements using a
calcium fluoride diffuser disk.
— In Bibliography, ISO 31-6:1992 was replaced by current version ISO 80000-7, same for ISO 11146 with
ISO 11146-1 and ISO 11146−2, ISO 11554 and ISO 12005 no longer cited dated. Also replacement of
[5]" [6]
former citations " by latest edition of SEMI MF1048-0217 .
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
v
ISO 13696:2022(E)
Introduction
In most applications, scattering in optical components reduces the efficiency and deteriorates the
image-forming quality of optical systems. Scattering is predominantly produced by imperfections of
the coatings and the optical surfaces of the components. Common surface features, which contribute
to optical scattering, are imperfections of substrates, thin films and interfaces, surface and interface
roughness, or contamination and scratches. These imperfections deflect a fraction of the incident
radiation from the specular path. The spatial distribution of this scattered radiation is dependent on
the wavelength of the incident radiation and on the individual optical properties of the component. For
most applications in laser technology and optics, the amount of total loss produced by scattering is a
useful quality criterion of an optical component.
This document describes a testing procedure for the corresponding quantity, the total scattering
value, which is defined by the measured values of backward scattering or forward scattering. The
measurement principle described in this document is based on an Ulbricht sphere as the integrating
element for scattered radiation. An alternative apparatus with a Coblentz hemisphere, which is also
frequently used for collecting scattered light, is described in Annex A.
vi
INTERNATIONAL STANDARD ISO 13696:2022(E)
Optics and photonics — Test method for total scattering by
optical components
1 Scope
This document specifies procedures for the determination of the total scattering by coated and uncoated
optical surfaces. Procedures are given for measuring the contributions of the forward scattering or
backward scattering to the total scattering of an optical component.
This document applies to coated and uncoated optical components with optical surfaces that have a
radius of curvature of more than 10 m. Measurement wavelengths covered by this document range
from the ultraviolet above 250 nm to the infrared spectral region below 15 µm. For measurements in
the deep ultraviolet between 190 nm to 250 nm, specific methods are considered and are described.
Generally, optical scattering is considered as neglectable for wavelengths above 15 µm.
2 Normative references
The following documents are referred to in the text in such a way, that some or all of their content
constitutes requirements of this document. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any amendments) applies.
ISO 11145, Optics and photonics — Lasers and laser-related equipment — Vocabulary and symbols
ISO 14644-1, Cleanrooms and associated controlled environments — Part 1: Classification of air cleanliness
by particle concentration
3 Terms, definitions and symbols
3.1 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 11145 and the following apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1.1
scattered radiation
fraction of the incident radiation that is deflected from the specular optical path
3.1.2
front surface
optical surface that interacts first with the incident radiation
3.1.3
rear surface
surface that interacts last with the transmitted radiation
ISO 13696:2022(E)
3.1.4
backward scattering
fraction of radiation scattered by the optical component into the backward halfspace
Note 1 to entry: Backward halfspace is defined by the halfspace that contains the incident beam impinging upon
the component and that is limited by a plane containing the front surface of the optical component.
3.1.5
forward scattering
fraction of radiation scattered by the optical component into the forward halfspace
Note 1 to entry: Forward halfspace is defined by the halfspace that contains the beam transmitted by the
component and that is limited by a plane containing the rear surface of the optical component.
3.1.6
total scattering
ratio of the total power generated by all contributions of scattered radiation (3.1.1) into the forward or
the backward halfspace to the power of the incident radiation
Note 1 to entry: The halfspace in which the scattering is measured should be clearly stated.
Note 2 to entry: The sum of the measured forward and backward scattering does not include the contribution of
the bulk material in the optical component. In case the volume scattering of the component is not negligible, the
total scatter losses may exceed the sum of forward and backward scattering.
Note 3 to entry: Total scattering is equal to forward or backward scattering, and is neither the sum of both nor
the sum of all scattering contributions.
3.1.7
diffuse reflectance standard
diffuse reflector with known total reflectance
Note 1 to entry: Commonly used diffuse reflectance standards are fabricated from barium sulfate or
polytetrafluoroethylene powders (see Table 2). The total reflectance of reflectors freshly prepared from these
materials is typically greater than 0,98 in the spectral range given in Table 2, and it can be considered as a
100 % reflectance standard. For increasing the accuracy, diffuse reflectance standards with lower reflectance
values can be realized by mixtures of polytetrafluoroethylene powder and powders of absorbing materials,
see Reference [6]. Further concepts for diffuse reflectance standards include optical surfaces with specially
prepared microstructures, metal-coated diffusers or diffuse transparent reference samples. A versatile method
on the basis of a calcium fluoride diffuser disk for the wavelength range from 250 nm down in the ultraviolet
range is described in Annex E.
3.1.8
range of acceptance angle
range of scattering angles in the reflecting or transmitting hemisphere, which are collected by the
integrating element
Note 1 to entry: The maximum polar acceptance angle with respect to the sample normal is 85°.
Note 2 to entry: The radiant power around the specular transmitted or reflected beam is not collected by the
integrating element in a cone with an opening angle of 2° or less.
3.1.9
angle of polarization
angle between the major axis of the instantaneous polarization ellipse of the incident radiation and the
plane of incidence
Note 1 to entry: For non-normal incidence, the plane of incidence is defined by the plane which contains the
direction of propagation of the incident radiation and the normal at the point of incidence.
Note 2 to entry: The angle of polarization, γ, is identical to the azimuth, Φ (according to ISO 12005), if the reference
axis is located in the plane of incidence.
ISO 13696:2022(E)
3.2 Symbols and units of measure
Table 1 — Symbols and units of measure
Symbol Term Unit
λ wavelength nm
α angle of incidence degrees
γ angle of polarization degrees
d beam diameter on the surface of the specimen mm
σ
d largest beam diameter at a beam port mm
σ,p
P power of the incident radiation W
inc
P total power, backward scattered radiation W
bac
P total power, forward scattered radiation W
for
σ total scattering
TS
ρ backward scattering
TS
τ forward scattering
TS
a
V detector signal for the specimen, backward scattering
s,bac
a
V detector signal for the specimen, forward scattering
s,for
a
V detector signal, diffuse reflectance standard
c
a
V detector signal, test ports open
u
τ transmittance of specimen at wavelength, λ
s
ρ reflectance of specimen at wavelength, λ
s
r test site position
i
N number of test sites per surface
a
The unit depends on the measurement device and is therefore not specified here.
4 Test method
4.1 Principle
The fundamental principle (see Figure 1) of the measurement apparatus is based on the collection and
integration of the scattered radiation. For this purpose, a hollow sphere with a diffusely reflecting
coating on the inner surface (Ulbricht sphere) is used. Beam ports are necessary for the transmission of
the test beam and the specularly reflected beam through the wall of the sphere. The sample is attached
to one of these ports forming a part of the inner surface of the sphere. For the measurement of the
backward scattering, the specimen is located at the exit port. The forward scattering is determined by
mounting the specimen to the entrance port. The scattered radiation is integrated by the sphere and
measured by a suitable detector, which is attached to an additional port at an appropriate position. A
diffuse reflectance standard is used for calibration of the detector signal.
4.2 Measurement arrangement and test equipment
4.2.1 General
The measurement facility used for the determination of the total scattering is divided into four
functional sections, which are described in detail below. One functional section consists of the radiation
source and the beam preparation system. Two different components are defined by the integration and
detection of the scattered radiation. Another section is formed by the sample holder and its optional
accessories.
ISO 13696:2022(E)
Key
1 radiation source 10 exit port
2 chopper 11 beam stop
3 spatial filter 12 sample
4 beam splitter 13 radiation baffles
5 power detector 14 detector, diffuser
6 power meter 15 beam stop
7 entrance port 16 chopper signal
8 Ulbricht sphere 17 lock-in amplifier (optional)
9 coating 18 detector signal
Figure 1 — Schematic arrangement for the measurement of total scattering
(configuration for backward scattering with phase sensitive detection scheme)
4.2.2 Radiation source
As radiation sources, lasers are preferred because of their excellent beam quality and the high power
density achievable on the sample surface. For special applications, for example involving the wavelength
dependence of scattering, different conventional radiation sources may be used.
The temporal power variation of the radiation source shall be measured and documented. For this
purpose, a beam splitter and a monitor detector are installed. The power at the sample surface shall be
measured by a calibrated detector for both test locations at the entrance and exit port of the integrating
element.
4.2.3 Beam preparation system
The beam preparation system consists of a spatial filter and additional apertures, if necessary, for
cleaning the beam. For measurements involving conventional radiation sources, additional optical
elements are required for the shaping and collimation of the beam. The beam diameter, d , at the surface
σ
ISO 13696:2022(E)
of the specimen shall be greater than 0,4 mm. No radiation power shall be present in the collimated
beam profile beyond radial positions exceeding the beam radius by a factor of 5.
NOTE 1 The behaviour of the measured total scatter value can be dependent on the beam diameter and the
beam profile (see Annex D).
On the sample surface, the beam profile shall be smooth without local power density values exceeding
the average power density within the beam diameter, d , by a factor of three. For measurement systems
σ
with a laser as the radiation source, a TEM -operation with a diffraction-limited Gaussian beam
profile is recommended. The defined state and angle of polarization shall be selected. For measurement
systems using conventional radiation sources, an unpolarised beam with a circular profile shall be
realized. The beam profile on the sample surface shall be free of diffraction patterns and parasitic
spots in the outward region. The spatial beam profile on the sample surface shall be recorded and
documented.
Optical elements, as for example beam deflection mirrors or beam splitters, may have a reflectivity
which depends on the polarization state of the incident radiation, and they may also deteriorate the
sensitivity of the measurement. The last optical element in front of the integrating sphere shall be
positioned such that the measurement is not influenced by it.
For the fractions of the beam reflected and transmitted by the sample, efficient beam dumps shall be
used to suppress backscattering into the integrating sphere.
NOTE 2 An efficient beam dump can be constructed with a stack of optically absorbing neutral density filters.
These filters are arranged for non-normal angles of incidence in a housing with optically absorbing inner walls.
4.2.4 Integrating sphere
An integrating sphere is used for the collection and integration of the radiation scattered by the sample.
The sphere shall be equipped with beam ports for the entrance and the exit of the probe beam and the
fraction of the beam which is specularly reflected by the specimen. The inner surface shall be coated
with a highly diffusive reflecting material with a Lambertian characteristic and diffuse reflectivity
higher than 97 % for the measurement wavelength. Selected materials suitable for this coating and the
corresponding spectral ranges are listed in Table 2.
NOTE 1 Aging of the diffuse reflecting material on the inner walls of the sphere can occur. Corresponding
effects can be detected by monitoring the signal of the sphere with attached diffuse reflectance standard during
long term usage.
Table 2 — Selected materials for coating of the inner surface of the integrating sphere
and for diffuse reflectance standards
Spectral range
Material
µm
Barium sulfate 0,35 to 1,4
Magnesium oxide 0,25 to 8,0
Polytetrafluoroethylene 0,20 to 2,5
Gold coating, matt 0,70 to 20
The diameters of the beam ports shall be equal and shall exceed the largest beam diameter, d , of the
σ,p
probe beam at the beam ports by at least a factor of five. The port for the detector shall be adapted
to the sensitive area of the detecting element. The detailed shape of the ports shall be optimized for
minimum deterioration of the integrating action and for a contact-free installation of the test sample.
Baffles coated with the same material as the inner surface of the sphere shall be installed between the
detector port and the exit as well as the entrance port. Radiation baffles in front of the detector port are
recommended in order to shield the detector against radiation directly scattered by the specimen to
the location of the detector. For compensation of spatial inhomogeneities of the detector sensitivity, an
optional diffuser may be attached to the detector.
ISO 13696:2022(E)
An interval from 2° to 85° is defined as the minimum range of the acceptance angle for scattered
radiation. The minimum size of the integrating sphere is specified by the lower limit of 2,0° for the
acceptance angle.
NOTE 2 The determination of the minimum size of the integrating sphere originates from the largest beam
diameter, d , at the beam ports of the Ulbricht sphere. The minimum diameter of the port, where the beam
σ,p
diameter appears with largest value d is directly related to this beam diameter by the factor of five. The
σ,p
minimum sphere diameter is then calculated on the basis of the minimum diameter of the entrance port and the
lower limit for the acceptance angle. (The minimum diameter of the integrating sphere is at least 72 times the
beam diameter, d .)
σ,p
For measurement systems with radiation sources other than lasers or special measurement conditions,
the beam diameter, d , achievable may result in an impractically large size of the integrating sphere.
σ,p
In such cases, the diameters of the entrance and exit ports shall be adjusted to a value that guarantees
no vignetting of the incident, transmitted and reflected beams. The lower and upper limits for the
acceptance angles shall be documented.
For specific problems caused by limitations of the integrating element, the detectors and radiation
source shall be taken into account for an application of this document below a wavelength of 250 nm.
The amount of radiation scattered is a function of both the different contributions of scattering
mechanism acting in the specimen and the wavelength of the radiation. In practice, scattering becomes
less important at longer wavelengths.
As an alternative, a Coblentz half-sphere with an appropriate reflecting surface may be used. A typical
set-up and the corresponding measurement procedure are described in Annex A.
4.2.5 Detection system
For detection of the scattered radiation, a detector is used that is appropriate for the wavelength range
of the radiation source. The detector system shall have a sufficient sensitivity for the radiation source
and a dynamic range greater than 10 with a deviation from linearity of less than 2 %. The size of the
sensitive detector area shall be optimized in order to exclude a deterioration of the integration process
in the sphere and influence of speckle on the measurement. The detector is attached to the detection
port of the sphere with its sensitive area forming approximately one part of the inner surface.
For shielding the detector against the direct radiation scattered onto the sensitive area by the specimen,
radiation baffles shall be installed in the integrating sphere. The surfaces of these baffles shall be coated
with or consisting of the same material as the inner surface of the integrating sphere. An additional
diffusing window may be installed in front of the detector in order to compensate for spatial variations
of the detector sensitivity.
A phase sensitive detection technique or an advanced data acquisition technique is recommended for
improved detection sensitivity.
NOTE Phase sensitive detection schemes are typically operated in conjunction with a radiation chopper or
another suitable technique installed into the beam path to modulate the output beam. The processing of the
detector signal is performed by a lock-in amplifier that is synchronized to the modulation frequency of the
radiation.
4.2.6 Specimen holder
The specimen holder shall allow for a non-destructive mounting and for a precise placement of the
specimen with respect to the ports of the integrating sphere. For scanning the surface of the specimen,
the holder may be equipped with a positioning system that is adapted to the desired lateral motion of
the sample.
4.3 Arrangement with high sensitivity
–4
For total scatter measurements of specimens with total scattering values below 10 , steps shall be
taken to maximize the sensitivity of the arrangement. In this case, only lasers operating in a stable
ISO 13696:2022(E)
TEM -mode shall be used as a radiation source. The integrating sphere shall be installed at a large
enough distance from the last optical element of the beam preparation system to enable scattering
from the spatial filter to be removed. To eliminate the need for neutral density filters for calibration,
a dynamic range of the detection system greater than twice the reciprocal value of the minimum
detectable total scattering is recommended. To decrease the contribution from Rayleigh scattering
to the background noise of the measurement system, flushing of the arrangement with pure Helium
gas or evacuation is recommended. Shielding the apparatus from radiation sources in the vicinity is
recommended.
4.4 Preparation of specimens
The specimen shall have specified optical imaging properties that are defined by its refractive, reflective
or diffractive functioning. This test method is not destructive and shall be applied to the actual part.
Wavelength, angle of incidence and polarization of the radiation as used in the test shall be in accordance
with the specifications given by the manufacturer for normal use. If ranges are given for the values of
these parameters, an arbitrary combination of wavelength, angle of incidence and polarization within
these ranges may be chosen.
Storage, cleaning and preparation of the specimen is carried out according to directions given by the
manufacturer for normal use.
In the absence of manufacturer-specified instructions, the following procedure shall be used.
The specimen shall be stored, prepared and tested in an environment with relative humidity higher
than 40 % and lower than 60 %. Prior to testing, the specimen shall be kept in this testing environment
in the packaging of the manufacturer for 24 h. The handling procedure of the specimen shall be
optimized for a minimum exposure time of the specimen to the test environment.
The specimens shall be kept under cleanroom conditions in accordance with ISO 14644-1 as specified
in Table 3 during the entire unpacking and preparation procedure without interruption. The specimen
shall be handled by the non-optical surfaces only.
Table 3 — Cleanroom classes for the specimen preparation environment
Expected σ
TS
Environment for specimen preparation
%
σ ≥ 0,1 Cleanroom better than class 7
TS
0,1 > σ > 0,01 Cleanroom better than class 6
TS
σ ≤ 0,01 Cleanroom better than class 5
TS
NOTE The cleanroom classes are defined according to ISO 14644-1.
If contaminants are observed on the specimen or if the original packing was unsealed under undefined
environmental conditions, the surface shall be cleaned. The cleaning procedure shall be documented.
If the contaminants are not removable, they shall be documented by photographic and/or electronic
means before testing.
5 Procedure
5.1 General
Conditions as stated in Table 3 for the specimen preparation environment also apply for the measurement
system. For repeatable measurements, the specimens shall be kept under these conditions without
interruption during the entire test procedure.
ISO 13696:2022(E)
5.2 Alignment procedure
5.2.1 General
The alignment of the experimental arrangement is of central importance for the accuracy of the
measurement.
5.2.2 Alignment of the beam
The beam shall pass through the centre of the entrance and exit port of the integrating sphere. The
beam parameters shall have been measured by a beam profile measurement system. For a coarse
inspection of the beam prior to the mounting of a specimen, a scattering surface (e.g. white cardboard)
may be used for assessing the beam spot at the entrance and exit ports.
5.2.3 Alignment of the specimen
For the measurement of backward scattering, the specimen is attached to the exit port of the integrating
sphere with the front surface pointing towards the sphere. The portion of the beam reflected by the
component shall exit the entrance port of the sphere without influencing the measurement.
For the measurement of forward scattering, the specimen is attached to the entrance port of the
integrating sphere with the rear surface pointing towards the sphere. The specularly reflected beam
shall be aligned such that interference with the radiation source is excluded. The transmitted beam
shall leave the sphere at the centre of the exit port.
For the alignment of the specimen, the angle of incidence shall be tilted slightly from the normal
direction. An angle of 1,5° with respect to the normal direction shall not be exceeded for the
measurement.
NOTE For integrating spheres with two circular beam ports, this implies that the incident beam deviates
slightly from the centre of the beam ports, see Reference [6].
For other angles of incidence, the experimental arrangement shall be adapted to the special geometry,
and the alterations shall be documented. The installation of a third beam port is allowable for the path
of the radiation specularly reflected by the specimen. If a spatial scanning system is provided, the
alignment conditions for the specimen shall be fulfilled for the entire scanning range.
5.3 Measurement procedure
In the first step, a calibrated power meter shall be placed at the measurement position and the beam
power as well as the signal of the monitor detector shall be recorded. The power meter shall be removed
and a diffuse reflectance standard shall be attached to the exit port such that its surface forms a part of
the inner surface of the integrating sphere. The reading, V , of the detection system shall be recorded.
c
To avoid errors caused by nonlinearities of the detection system, neutral density filters with known
attenuation may be used. For the evaluation of the background noise signal, the diffuse reflectance
standard shall be removed, and the signal of the unloaded sphere, V , shall be recorded.
u
In the next step, the specimen shall be attached to the port. After aligning the specimen, the reading,
V or V , of the detection system shall be recorded for the position or scanning range provided on
s,bac s,for
the specimen. The direction of scanning and the geometric scanning range on the surface of the optical
component shall be documented. The scanning range shall be referred to fixed reference points on the
specimen. It is acceptable to make marks at locations on the non-optical surfaces of the specimen as
reference points.
If scanning of the specimen is not specified, the procedure shall be repeated for at least five different
beam positions r on the specimen surface. For samples with low uniformity of the surface, an increased
i
number of different beam positions, r , shall be measured.
i
ISO 13696:2022(E)
6 Evaluation
6.1 Determination of the total scattering value
For a measurement without scanning the surface, the forward and backward total scatter values are
determined from the measured signals, V and V , by the following Formulae (1) and (2):
s c
Vr()
1 N
s,for i
τ = (1)
TS,rs ∑
i=1
N V
c
Vr()
N
s,bac i
ρ = (2)
TS,rs ∑
i=1
N V
c
NOTE 1 The subscript rs in τ and ρ indicates a measurement without scanning of the specimen.
TS,rs TS,rs
In case a calibration sample with arbitrary diffuse reflectance is used, the signal, V , shall be corrected
c
in respect to the actual reflectance of the calibration sample.
A two-dimensional or three-dimensional plot (see Figure 2) shall be used for the presentation of the
total scat
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