EN ISO 25178-603:2025

SLOVENSKI STANDARD
01-maj-2025
Specifikacija geometrijskih veličin izdelka (GPS) - Tekstura površine: ravna - 603.
del: Konstrukcije in značilnosti nekontaktnih instrumentov (interferometrija s
faznim zamikom) (ISO 25178-603:2025)
Geometrical product specifications (GPS) - Surface texture: Areal - Part 603: Design and
characteristics of non-contact (phase shifting interferometry) instruments (ISO 25178-
603:2025)
Geometrische Produktspezifikation (GPS) - Oberflächenbeschaffenheit: Flächenhaft -
Teil 603: Aufbau und Merkmale von berührungslos messenden Geräten
(phasenschiebende Interferometrie) (ISO 25178-603:2025)
Spécification géométrique des produits (GPS) - État de surface: Surfacique - Partie 603:
Conception et caractéristiques des instruments sans contact (à interférométrie à
glissement de franges) (ISO 25178-603:2025)
Ta slovenski standard je istoveten z: EN ISO 25178-603:2025
ICS:
17.040.20 Lastnosti površin Properties of surfaces
17.040.40 Specifikacija geometrijskih Geometrical Product
veličin izdelka (GPS) Specification (GPS)
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

EN ISO 25178-603
EUROPEAN STANDARD
NORME EUROPÉENNE
February 2025
EUROPÄISCHE NORM
ICS 17.040.20 Supersedes EN ISO 25178-603:2013
English Version
Geometrical product specifications (GPS) - Surface texture:
Areal - Part 603: Design and characteristics of non-contact
(phase shifting interferometry) instruments (ISO 25178-
603:2025)
Spécification géométrique des produits (GPS) - État de Geometrische Produktspezifikation (GPS) -
surface: Surfacique - Partie 603: Conception et Oberflächenbeschaffenheit: Flächenhaft - Teil 603:
caractéristiques des instruments sans contact (à Aufbau und Merkmale von berührungslos messenden
interférométrie à glissement de franges) (ISO 25178- Geräten (phasenschiebende Interferometrie) (ISO
603:2025) 25178-603:2025)
This European Standard was approved by CEN on 21 February 2025.

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, Türkiye 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
© 2025 CEN All rights of exploitation in any form and by any means reserved Ref. No. EN ISO 25178-603:2025 E
worldwide for CEN national Members.

Contents Page
European foreword . 3

European foreword
This document (EN ISO 25178-603:2025) has been prepared by Technical Committee ISO/TC 213
"Dimensional and geometrical product specifications and verification" in collaboration with Technical
Committee CEN/TC 290 “Dimensional and geometrical product specification and verification” the
secretariat of which is held by AFNOR.
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 August 2025, and conflicting national standards shall
be withdrawn at the latest by August 2025.
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 25178-603:2013.
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, Türkiye and the
United Kingdom.
Endorsement notice
The text of ISO 25178-603:2025 has been approved by CEN as EN ISO 25178-603:2025 without any
modification.
International
Standard
ISO 25178-603
Second edition
Geometrical product specifications
2025-02
(GPS) — Surface texture: Areal —
Part 603:
Design and characteristics of
non-contact (phase shifting
interferometry) instruments
Spécification géométrique des produits (GPS) — État de surface:
Surfacique —
Partie 603: Conception et caractéristiques des instruments sans
contact (à interférométrie à glissement de franges)
Reference number
ISO 25178-603:2025(en) © ISO 2025

ISO 25178-603:2025(en)
© ISO 2025
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 25178-603:2025(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Instrument requirements . 3
5 Metrological characteristics . 4
6 Design features . 4
7 General information . 4
Annex A (informative) Principles of PSI instruments for areal surface topography measurement . 5
Annex B (informative) Sources of measurement error for PSI instruments .10
Annex C (informative) Relationship to the GPS matrix model . 14
Bibliography .15

iii
ISO 25178-603:2025(en)
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 document 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).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
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 213, Dimensional and geometrical product
specifications and verification, in collaboration with the European Committee for Standardization (CEN)
Technical Committee CEN/TC 290, Dimensional and geometrical product specification and verification, in
accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This second edition cancels and replaces the first edition (ISO 25178-603:2013), which has been technically
revised.
The main changes are as follows:
— removal of the terms and definitions now specified in ISO 25178-600;
— revision of all terms and definitions for clarity and consistency with other ISO standards documents;
— addition of Clause 4 for instrument requirements, which summarizes normative features and
characteristics;
— addition of Clause 5 on metrological characteristics;
— addition of Clause 6 on design features, which clarifies the types of instruments relevant to this document;
— addition of an information flow concept diagram in Clause 4;
— revision of Annex A describing the principles of instruments addressed by this document;
— addition of Annex B on metrological characteristics and influence quantities, replacement of the
normative table of influence quantities with an informative description of common error sources and
how these relate to the metrological characteristics in ISO 25178-600.
A list of all parts in the ISO 25178 series can be found on the ISO website.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.

iv
ISO 25178-603:2025(en)
Introduction
This document is a geometrical product specification (GPS) standard and is to be regarded as a general GPS
standard (see ISO 14638). It influences chain link F of the chains of standards on profile and areal surface
texture.
The ISO GPS matrix model given in ISO 14638 gives an overview of the ISO GPS system of which this document
is a part. The fundamental rules of ISO GPS given in ISO 8015 apply to this document and the default decision
rules given in ISO 14253-1 apply to the specifications made in accordance with this document, unless
otherwise indicated.
For more detailed information on the relation of this document to other standards and the GPS matrix model,
see Annex C.
This document includes terms and definitions relevant to the phase shifting interferometry (PSI)
instruments for the measurement of areal surface topography. Annex A briefly summarizes PSI instruments
and methods to clarify the definitions and to provide a foundation for Annex B, which describes common
sources of uncertainty and their relation to the metrological characteristics of PSI.
NOTE Portions of this document, particularly the informative sections, describe patented systems and methods.
This information is provided only to assist users in understanding the operating principles of PSI instruments. This
document is not intended to establish priority for any intellectual property, nor does it imply a license to proprietary
technologies described herein.

v
International Standard ISO 25178-603:2025(en)
Geometrical product specifications (GPS) — Surface
texture: Areal —
Part 603:
Design and characteristics of non-contact (phase shifting
interferometry) instruments
1 Scope
This document specifies the design and metrological characteristics of phase shifting interferometry (PSI)
instruments for the areal measurement of surface topography. Because surface profiles can be extracted
from areal surface topography data, the methods described in this document are also applicable to profiling
measurements.
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 25178-600:2019, Geometrical product specifications (GPS) — Surface texture: Areal — Part 600:
Metrological characteristics for areal topography measuring methods
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 25178-600 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
phase shifting interferometry
PSI
method for measuring areal surface topography from the surface height dependence of an interferometric
signal, whereby the interference phase is estimated from two or more digitized interference images acquired
over a sequence of controlled phase shifts
Note 1 to entry: In this document, PSI refers specifically to methods that employ time-dependent phase shifting
mechanisms (3.8). Other methods of acquiring and analysing interference patterns, including parallel or instantaneous
methods using polarization or carrier fringes, are outside the scope of this document.
Note 2 to entry: ISO/TR 14999-2:2019, 6.4.4, provides further information on synchronous detection and PSI.
Note 3 to entry: PSI instruments are most often employed for measurements of optically smooth surfaces, as defined
in ISO 25178-600:2019, 3.4.4.
ISO 25178-603:2025(en)
3.2
interference objective
microscope objective adapted with a reference path and reference surface for the generation of interference
patterns superimposed on the image of a sample surface
Note 1 to entry: Interference objectives are used in PSI (3.1) instruments that are configured as microscopes. Other
configurations of PSI instruments, particularly for fields of view larger than about 10 mm, can have interferometer
designs that are not based on microscope objectives.
Note 2 to entry: Annex A provides example types of interference objective in common usage.
3.3
linear phase shifting interferometry
linear PSI
PSI (3.1) method that relies on sampling an interference signal over a sequence of evenly spaced interference
phase shifts
3.4
sinusoidal phase shifting interferometry
sinusoidal PSI
PSI (3.1) method that relies on sampling an interference signal over a sequence of sinusoidally-varying
interference phase shifts
3.5
phase shifting interferometry algorithm
PSI algorithm
algorithm for the data processing procedure, including the mathematical equations, used to calculate the
topography from two or more digitized interference images acquired over a sequence of controlled phase shifts
3.6
equivalent wavelength
λ
eq
constant value equal to twice the change in surface topography height that produces one full cycle of
interference phase change (equivalent to one interference fringe)
Note 1 to entry: The equivalent wavelength is a definition in the context of PSI (3.1) for the measurement
optical wavelength, defined as the “effective value of the wavelength of the light used to measure a surface” in
ISO 25178-600:2019, 3.3.3.
Note 2 to entry: This definition corresponds to the measurement configuration described in Annex A. There can be
different definitions for other measurement configurations.
Note 3 to entry: The equivalent wavelength can be calculated from contributions such as the light source wavelength
together with other factors related to the instrument design, or can be calibrated using a procedure corresponding to
the definition of the equivalent wavelength.
3.7
phase change on reflection
PCOR
change in interference phase attributable to the optical properties of a sample surface independent of
surface height
Note 1 to entry: The PCOR is most relevant to non-dielectric materials such as metals and surfaces that have thin
layers of differing materials producing thin-film effects.
Note 2 to entry: The PCOR can vary over the sample surface comprised of an optically non-uniform material (see
ISO 25178-600:2019, 3.4.6).
ISO 25178-603:2025(en)
3.8
phase shifting mechanism
device that imparts controlled phase shifts to an interference signal
Note 1 to entry: The phase shift mechanism can generate phase shifts by an axial scan motion of the part or of the
interference objective (see ISO 25178-607:2019, 3.5), or other methods, such as displacement of the reference surface.
3.9
phase unwrapping algorithm
algorithm used to extend the surface topography measurement range beyond a single cycle of interference
phase (equivalent to one interference fringe), by removing excess multiples of 2π between the phase values
of neighbouring image points
Note 1 to entry: ISO/TR 14999-2:2019, 6.6, provides further details regarding phase unwrapping.
3.10
fringe-order error
2π error
error in the identification of the correct fringe when calculating relative
heights using interference phase for surface topography calculations
Note 1 to entry: Fringe-order errors are integer multiples of one-half the equivalent wavelength (3.6) in height.
4 Instrument requirements
An instrument according to this document shall perform areal surface topography measurements of a sample
surface using PSI. The instrument can comprise an interference objective or alternative interferometer
assembly and a phase shifting mechanism. The instrument shall acquire data using linear PSI, sinusoidal PSI
or other phase shifting patterns consistent with the definition of PSI. The instrument shall convert acquired
data to an areal topography using a PSI algorithm and a calculated or assumed equivalent wavelength. A
phase unwrapping algorithm shall be employed as needed to reduce fringe-order error.
Figure 1 shows the information flow between these elements for a PSI microscope, from the real surface to
a scale-limited surface. Example PSI hardware, techniques and error sources are given in Annexes A and B.

ISO 25178-603:2025(en)
Key
measurand
operator with intended modification
operator without intended modification
Figure 1 — Information flow concept diagram for PSI
5 Metrological characteristics
The standard metrological characteristics for areal surface texture measuring instruments specified in
ISO 25178-600 shall be considered when designing and calibrating the instrument.
Annex B describes sources of measurement error that can influence the calibration result.
6 Design features
Standard design features described in ISO 25178-600 shall be considered in the design.
Annex A provides examples of specific design features of PSI instruments.
7 General information
The relationship between this document and the GPS matrix model is given in Annex C.

ISO 25178-603:2025(en)
Annex A
(informative)
Principles of PSI instruments for areal surface topography
measurement
A.1 General
PSI is a mature technology and there are substantial resources in existing ISO documents listed in the
[9][10][11]
bibliography and in the published literature regarding instrument design and theory of operation.
[12][13]
This annex provides a summary with the goal of clarifying terms and definitions as well as some of
the influence quantities that contribute to the metrological characteristics of PSI.
A.2 Instrument design
PSI instruments for areal surface topography measurement comprise a variety of designs. The testing of
optical components such as lenses, mirrors and prisms often relies on the laser Fizeau geometry, used for
[14][15]
polished surfaces from a few millimetres to over a metre in size. This annex describes the use of PSI
together with light microscopy for areal surface topography using a mechanical phase shifting mechanism.
Refer to ISO/TR 14999-1 for general terms and definitions related to light interferometry and to ISO 10934
for general terms and definitions related to light microscopy.
Figure A.1 shows an interference microscope with imaging optics. The phase shifting mechanism imparts a
controlled phase shift by means of an axial scan ζ of the interference objective towards the sample surface
along the z-axis direction (see ISO 25178-607:2019, 3.5). The sample surface lies nominally within the plane,
consistent with the coordinate system defined in ISO 25178-600:2019, 3.1.2, and is imaged to the electronic
camera. The measurement principle is to determine the surface height at each point on the sample surface
by analysis of multiple interference patterns acquired during a sequence of controlled phase shifts.

ISO 25178-603:2025(en)
Key
A workpiece E phase shifting mechanism
B light source F electronic camera
C beam splitter G data acquisition and control
D interference objective H interference pattern
ζ scanning motion
Figure A.1 — Interference microscope for PSI measurements of the areal surface topography
Light sources for interference microscopy are usually spatially incoherent, exemplified by incandescent lamps
or white-light-emitting diodes (see ISO 10934:2020, 3.1.73). The light source can include interchangeable
filters for adjusting the illumination spectrum (see ISO 10934:2020, 3.1.55). In Figure A.1, the light source is
shown imaged into the objective pupil in the epi-illumination Köhler geometry (see ISO 10934:2020, 3.1.73.2
and 3.1.73.3). Many instruments have adjustable light stops for controlling the size of the illumination field
[9]
as well as the illumination aperture (see ISO 10934:2020, 3.1.38.6).
PSI instruments use interference objectives in place of conventional microscope objectives defined in
ISO 10934:2020, 3.1.106. Typically these objectives are compatible with extended, incoherent light sources.
[9] [16][17]
Figure A.2 shows two common types of interference objective, the Michelson and Mirau type. Other
[18][19]
designs in common use for PSI include the Linnik objective, and the Zygo Wide Field (ZWF) objective.
[20]
Table A.1 provides example specifications, including the lateral resolution according to the Sparrow
criterion for a wavelength of 570 nm (see ISO 25178-600:2019, 3.3.9).
Cameras for the visible wavelengths can be of the charge-coupled device (CCD) or complementary metal-
oxide semiconductor (CMOS type), with a format ranging from 300 000 pixels to over 4 million pixels.
Camera selection involves not only field size and number of pixels, but also the acquisition speed, response
linearity, quantum well depth, digitization resolution and the ability to shutter electronically. The net effect
of the camera, optics and data processing on the topographic lateral resolution is often summarized in the
instrument transfer function (ITF), defined in ISO 25178-600:2019, 3.1.19. See also References [21], [22],
[23] and [24].
Adjustments upwards or downwards of the position of the objective or a sample stage (not shown in
Figure A.1) bring the test surface into focus (see ISO 10934:2020, 3.1.65). Part setup usually requires a
nominal adjustment of both focus and tip/tilt, although automation can complete some or all these steps
(see, for example, autofocus, defined in ISO 10934:2020, 3.2.4).

ISO 25178-603:2025(en)
a) Michelson objective b) Mirau objective
Key
A lens
B reference surface
C beam splitter
D workpiece
Figure A.2 — Example types of interference microscope objectives for PSI measurements
Table A.1 — Example characteristics of interference objectives for PSI
Optical lateral reso-
Numerical aperture
lution
Magnification Type
A µm
N
1,4× ZWF 0,04 7,13
2,75× Michelson 0,08 3,56
5,5× Michelson 0,15 1,90
10× Mirau 0,30 0,86
50× Mirau 0,55 0,47
100× Mirau 0,85 0,34
ISO 25178-603:2025(en)
A.3 PSI theory of operation
[9][25][26]
Following a two-beam interference analysis, the interference signal at the camera for an individual
surface point of height z at a position x, y is as shown in Formula (A.1):
II=+ I cos θϕ−+γ (A.1)
()
DC AC
Where I and I are fixed coefficients, the surface-height dependent phase θ for an equivalent wavelength
DC AC
λ is as shown in Formula (A.2):
eq
z
θ =4π (A.2)
λ
eq
The phase shift imparted by a movement of the reference mirror is as shown in Formula (A.3):
ζ
ϕ=4π (A.3)
λ
eq
γ is a phase offset that is independent of z and ζ . The height is calculated from the detected phase as shown
in Formula (A.4):
λ
eq
z= (A.4)
4π
The interference fringes correspond to lines of equal intensity and follow the surface topography as
contours of equal surface height z. These fringes appear at intervals of 2π, which is equivalent in height to
one-half the equivalent wavelength λ , which for low numerical aperture systems is approximately equal to
eq
the mean value of the source emission wavelength. The phase offset γ in Formula (A.1) relates among other
factors to the reflection and transmission properties of the in
...