prEN ISO 25178-607

• Abstract:

  This document describes the influence quantities and instrument characteristics of confocal microscopy systems for areal measurement of surface topography. Because surface profiles can be extracted from surface topography images, the methods described in this document can be applied to profiling measurements as well.

• Status: Not Published
• Publication Date: 03-Apr-2028
• ICS: 17.040.20 - Properties of surfaces
• Technical Committee: CEN/TC 290 - Dimensional and geometrical product specification and verification
• Drafting Committee: CEN/TC 290 - Dimensional and geometrical product specification and verification
• Current Stage: 4020 - Submission to enquiry - Enquiry
• Start Date: 15-Oct-2026
• Completion Date: 15-Oct-2026
• Ref Project: oSIST prEN ISO 25178-607:2026 - Geometrical product specifications (GPS) - Surface texture: Areal - Part 607: Design and characteristics of non-contact (confocal microscopy) instruments (ISO/DIS 25178-607:2026)

• Revises: EN ISO 25178-607:2019 - Geometrical product specifications (GPS) - Surface texture: Areal - Part 607: Nominal characteristics of non-contact (confocal microscopy) instrumentss (ISO 25178-607:2018)
• Effective Date: 25-Sep-2024

SLOVENSKI STANDARD
01-december-2026
Specifikacija geometrijskih veličin izdelka (GPS) - Tekstura površine: ravna - 607.
del: Načrtovanje in značilnosti nekontaktnih (konfokalno mikroskopskih)
instrumentov (ISO/DIS 25178-607:2026)
Geometrical product specifications (GPS) - Surface texture: Areal - Part 607: Design and
characteristics of non-contact (confocal microscopy) instruments (ISO/DIS 25178-
607:2026)
Geometrische Produktspezifikation (GPS) - Oberflächenbeschaffenheit: Flächenhaft -
Teil 607: Aufbau und Merkmale von berührungslos messenden Geräten (konfokale
Mikroskopie) (ISO/DIS 25178-607:2026)
Spécification géométrique des produits (GPS) - État de surface: Surfacique - Partie 607:
Conception et caractéristiques des instruments sans contact (microscopie confocale)
(ISO/DIS 25178-607:2026)
Ta slovenski standard je istoveten z: prEN ISO 25178-607
ICS:
17.040.20 Lastnosti površin Properties of surfaces
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

DRAFT
International
Standard
ISO/DIS 25178-607
ISO/TC 213
Geometrical product specifications
Secretariat: BSI
(GPS) — Surface texture: Areal —
Voting begins on:
Part 607: 2026-10-15
Design and characteristics of non-
Voting terminates on:
2027-01-07
contact (confocal microscopy)
instruments
Spécification géométrique des produits (GPS) — État de surface:
Surfacique —
Partie 607: Conception et caractéristiques des instruments sans
contact (microscopie confocale)
ICS: 17.040.40
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document has not been edited by the ISO Central Secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
BE CONSIDERED IN THE LIGHT OF THEIR
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS.
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.
Reference number
ISO/DIS 25178-607:2026(en)
DRAFT
ISO/DIS 25178-607:2026(en)
International
Standard
ISO/DIS 25178-607
ISO/TC 213
Geometrical product specifications
Secretariat: BSI
(GPS) — Surface texture: Areal —
Voting begins on:
Part 607:
Design and characteristics of non-
Voting terminates on:
contact (confocal microscopy)
instruments
Spécification géométrique des produits (GPS) — État de surface:
Surfacique —
Partie 607: Conception et caractéristiques des instruments sans
contact (microscopie confocale)
ICS: 17.040.40
THIS DOCUMENT IS A DRAFT CIRCULATED
FOR COMMENTS AND APPROVAL. IT
IS THEREFORE SUBJECT TO CHANGE
AND MAY NOT BE REFERRED TO AS AN
INTERNATIONAL STANDARD UNTIL
PUBLISHED AS SUCH.
This document has not been edited by the ISO Central Secretariat.
IN ADDITION TO THEIR EVALUATION AS
BEING ACCEPTABLE FOR INDUSTRIAL,
© ISO 2026
TECHNOLOGICAL, COMMERCIAL AND
USER PURPOSES, DRAFT INTERNATIONAL
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
STANDARDS MAY ON OCCASION HAVE TO
ISO/CEN PARALLEL PROCESSING
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
BE CONSIDERED IN THE LIGHT OF THEIR
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
POTENTIAL TO BECOME STANDARDS TO
WHICH REFERENCE MAY BE MADE IN
or ISO’s member body in the country of the requester.
NATIONAL REGULATIONS.
ISO copyright office
RECIPIENTS OF THIS DRAFT ARE INVITED
CP 401 • Ch. de Blandonnet 8
TO SUBMIT, WITH THEIR COMMENTS,
CH-1214 Vernier, Geneva
NOTIFICATION OF ANY RELEVANT PATENT
Phone: [phone]
RIGHTS OF WHICH THEY ARE AWARE AND TO
PROVIDE SUPPORTING DOCUMENTATION.
Email: [e-mail]
Website: www.iso.org
Published in Switzerland Reference number
ISO/DIS 25178-607:2026(en)
ii
ISO/DIS 25178-607:2026(en)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Instrument requirements . 7
4.1 General .7
4.2 Information flow concept diagram of a confocal surface measuring instrument .7
5 Metrological characteristics . 8
6 Design features . 8
7 General information . 8
Annex A (informative) Principles of operation of confocal microscopes . 9
Annex B (informative) Sources of measurement error for confocal microscopy instruments . 17
Annex C (informative) Relation with the GPS matrix model .24
Bibliography .25

iii
ISO/DIS 25178-607:2026(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 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).
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.
This second edition cancels and replaces the first edition (ISO 25178-607:2019), which has been technically
revised.
The main changes are as follows:
— removal of terms and definitions specified in ISO 25178-600; revision of all terms and definitions for
clarity and consistency with other ISO standards documents;
— addition of Clause 4 on instrument requirements, which summarizes normative features and
characteristics and which provides an informative flow concept diagram;
— addition of Clause 5 on metrological characteristics;
— addition of Clause 6 on design features, which clarifies the types of instruments relevant to this document;
— revision of Annex A describing the principles of instruments addressed by this document;
— addition of Annex B on metrological characteristics and influence quantities, replacing 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/DIS 25178-607:2026(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 the chain link F and G 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 of 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 confocal microscopy method for the
measurement of areal surface topography. Annex A briefly summarizes typical configurations of confocal
microscopes 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 confocal
microscopes.
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 confocal microscopy.
This document is not intended to establish priority for any intellectual property, nor does it imply a license to
proprietary technologies described herein.

v
DRAFT International Standard ISO/DIS 25178-607:2026(en)
Geometrical product specifications (GPS) — Surface texture:
Areal —
Part 607:
Design and characteristics of non-contact (confocal
microscopy) instruments
1 Scope
This document specifies the design and metrological characteristics of confocal microscopy instruments
for areal measurement of surface topography. Because surface profiles can be extracted from areal surface
topography data, the methods described in this document can also be applied 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 following terms and definitions apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
3.1
confocal microscopy
surface topography measurement method, whereby axial scan through the focus of a microscope’s objective
provides by spatial optical filtering a series of optically sectioned point images, from which the height of a
topography point is determined
Note 1 to entry: As illustrated in Figure 1, the distinct optical sectioning behaviour of the confocal imaging is caused
by the reduced signal influence of the light coming from out-of-focus-points or points beside the observed point.
Note 2 to entry: In Figure 1, the optical imaging path is sketched on the base of a microscope with an infinite corrected
objective and a tube lens.
Note 3 to entry: There exist different instrumental principles for lateral sampling of a point to provide an areal
topography. Different names are listed in Table 1. Usual configurations are explained in Clauses A.3 to A.5.

ISO/DIS 25178-607:2026(en)
Table 1 — Examples of alternative terms sometimes used for a confocal microscope
Acronym Term
ICM imaging confocal microscope
LSCM laser-scanning confocal microscope (see also Clause A.3), Note 1
CLSM confocal laser-scanning microscope (same method as LSCM)
CSLM confocal-scanning laser microscope (same method as LSCM)
DSCM disc-scanning confocal microscope (see also Clause A.4)
PACM or PAM programmable array confocal microscope or programmable array microscope (see also
Clause A.5)
MSCM microdisplay scanning confocal microscope (same method as PACM)
RSOM real-time scanning optical microscope
CSOM confocal-scanning optical microscope
NOTE The similar term "laser-scanning microscope" is used for methods which are different from the confocal methods
described here. This can lead to misunderstanding.

ISO/DIS 25178-607:2026(en)
Key
PB imaging path to neighboring point
PD imaging path, surface defocussed
PI point imaging path
S surface in focus
O objective
FOV field of view (in x-y plane)
B beamsplitter
K collimator
IF image field
T tubelens
PT transmitting point
PR receiving point
L light source
D detector
SA sensor area (in x-y plane)
fT tube lens focal length
fO objective focal length
SD surface defocussed
NOTE For simplification the steering mechanism for lateral scan is omitted.

ISO/DIS 25178-607:2026(en)
Figure 1 — Light path of confocal point imaging
3.2
illumination pattern
arrangement of single or repetitive structures placed in a conjugate plane to the microscope’s object plane,
restricting the illuminated parts on the sample
Note 1 to entry: The illumination pattern can be a single pinhole, equally spaced pinholes on a grid, slits, parallel slits
or any other pattern that effectively reduces the amount of illuminated area.
Note 2 to entry: The planes named in the definition are explained in ISO 10934:2025, 3.1.31.
3.3
detection pattern
arrangement of single or repetitive structures placed in a conjugate plane to the microscope’s object plane,
blocking the out-of-focus light reflected from the surface and from elsewhere illuminated parts
Note 1 to entry: The illumination pattern and the detection pattern do not need to have the same geometry.
3.4
lateral scan
mechanical or optical displacement of the illumination and/or detection pattern to fulfil an optical section
image
Note 1 to entry: Clauses A.3 to A.5 describe the principle of lateral scan for typical confocal arrangements.
3.5
axial scan
mechanical or optical displacement between the sample under inspection and the imaging optics
Note 1 to entry: The axial scan axis of the microscope is nominally parallel to the imaging optics axis.
3.6
section image
result of the response of a confocal system from one in-plane scan at constant height relative to the sample
surface (skin model)
3.7
axial scan length
total range travelled by the confocal microscope axial scan (3.5), usually the total displacement between the
sample and the microscope’s objective translated along its optical axis during data acquisition
Note 1 to entry: This parameter can be limited by the overall range of the axial scanner. For the selected value of this
parameter the height range of the surface topography can be a limiting value.
3.8
axial response
signal recorded for an individual image point of the confocal image as a function of the axial scan (3.5)
position
Note 1 to entry: See Figure 2.

ISO/DIS 25178-607:2026(en)
Key
a normalized detector signal
b z-distance in arbitrary coordinates
1 background offset
2 full width at half maximum
3 axial response
Figure 2 — Schematic axial response signal
3.9
full width at half maximum
FWHM
Δ
z-HM
region of the axial response (3.8) near to the maximum of the confocal peak where
the signal falls to one-half of the maximum peak signal
Note 1 to entry: See Figure B.1.
3.10
maximum signal position
position of the axial scan (3.5) where the amplitude of the axial response (3.8) is maximum

ISO/DIS 25178-607:2026(en)
3.11
background offset
value of the axial response (3.8) for axial positions far from the maximum signal position (3.10)
Note 1 to entry: The background offset (3.11) (key 1 in Figure 2) might be caused by residual reflected and scattered
light within the instrument and from the sample.
Note 2 to entry: Methods exist which reduce or make use of background offset (3.11) effects.
3.12
axial step
distance between two consecutive confocal images during an axial scan (3.5)
3.13
confocal imaging rate
number of confocal images per second provided by a confocal microscope without axial scan (3.5)
3.14
axial scan rate
number of confocal images per second provided by a confocal microscope during an axial scan (3.5),
expressed as the number of acquired plane sections per second
Note 1 to entry: The axial scan rate is usually equal to or lower than the confocal imaging rate (3.13) depending on the
scanning hardware used and the processing algorithms.
3.15
reference area
formerly measured topography, to which the actually measured topography refers
Note 1 to entry: Confocal microscopes generally do not contain a physical areal reference according to
ISO 25178-600:2019, 3.1.1. Therefore the reference area is usually generated by the topography measurement of an
optical flat according to ISO 25178-70, type AFL.
Note 2 to entry: The reference area as a virtual height data set, representing a nearly perfect smooth and flat surface,
is stored in the microscope, e.g. for further corrections. It is used in the height map algorithm in the signal flow in
Figure 3.
Note 3 to entry: The reference area is stored in the microscope for each objective individually.
3.16
confocal peak location algorithm
algorithm used to estimate the maximum signal position (3.10) of the surface point from the axial response
(3.8)
Note 1 to entry: The maximum signal (confocal peak) position is equated to the axial location of the surface.
Note 2 to entry: The confocal peak is not necessarily represented by the absolute maximum of the axial response (3.8);
there are multiple algorithms (see B.3).
3.17
confocal stack
series of optical sections taken during an axial scan (3.5)
3.18
confocal topography image
areal topography image derived from a stack of optical sections obtained during an axial scan (3.5)
Note 1 to entry: Generally, for each pixel of the image the confocal peak location algorithm (3.16) is applied to the
confocal stack (3.17) to calculate the height of the surface.

ISO/DIS 25178-607:2026(en)
4 Instrument requirements
4.1 General
An instrument according to this standard shall perform areal surface topography measurements on a
sample surface using the principles of areal confocal microscopy. From the course of the confocal intensity
signal during the vertical scan the instrument shall calculate by the confocal peak location algorithm the
height of the observed point. Together with the lateral (x-y) scan mechanism and algorithm the instrument
shall convert the aquired data to an areal topography.
Informative example of confocal hardware, techniques and error sources are provided in Annex A,
respectively Annex B.
4.2 Information flow concept diagram of a confocal surface measuring instrument
Figure 3 shows the functional model with the signal flow in a confocal microscope, from the real surface to
a scale-limited surface.
Key
a measurand
b operator without intended modification
c operator with intended modification
Figure 3 — Signal flow in a confocal microscopy system

ISO/DIS 25178-607:2026(en)
5 Metrological characteristics
The standard metrological characteristics for areal surface texture measuring instruments are listed and
explained in ISO 25178-600 and 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 confocal microscopy instruments.
7 General information
The relationship between this document and the GPS matrix model is given in Annex C.

ISO/DIS 25178-607:2026(en)
Annex A
(informative)
Principles of operation of confocal microscopes
A.1 General
This annex aims to clarify terms and definitions as well as some of the influence quantities that contribute
to the metrological characterisics of confocal microscopes.
To recover a topography map of the surface, an in-plane scan is combined with an axial scan to produce a
sequence of optical sections. There are different techniques for in-plane scan, for illumination and detection
patterns, and for detector arrangements. Each different configuration optimizes a given application such as
maximization of light efficiency, optimization of signal-to-noise ratio, optimization of speed, simplification
or reduction of hardware cost, adaptation to different excitation wavelengths and others. Three typical
configurations of confocal microscopes are described in Clauses A.3 to A.5: laser scanning, disc scanning
and programmable array scanning.
In a data sheet the manufacturer of a confocal microscope can give values for the instrument features, which
give maximum performance concerning a specified surface measurement setup. The values given in a data
sheet are not necessarily all valid at the same time in one instrument setup.
A.2 Instrument design features
This Clause gives explanations, how the requirements of 4.1 are realized and how the hardware and software
features in the functional model of Figure 3 work together.
An axial drive and guiding mechanism along the optical axis provides the axial confocal scan and the
position information.
The confocal optical system contains in the optical path any order of structures which according to Figure 1
— effectively reduces the illuminated area on the surface,
— restricts the detected light only to that from the illuminated area.
As response to axial movement the confocal optical system delivers a confocal intensity signal.
The confocal signal is analysed by an algorithm which relates the calculated maximum of the signal with a
height value in the coordinate system of the instrument, see ISO 25178-600:2019, 3.1.2.
The coordinates of the peak heights are arranged in a map, for which the coordinates (x respectively y) are
generated from the x-y lateral scan measuring system (x-y-scan in Figure 3).
The lateral measurement area (see ISO 25178-600:2019, 3.1.4) can be extended by a lateral translation stage,
that delivers additional X’- and Y’-coordinates (X’-Y’ stage in Figure 3).
The resulting coordinate triples are present for further evaluation according to ISO 25178-2 and represent
the electromagnetic surface.
A S-filter delivers the primary surface.
The S-F surface according to ISO 25178-2 is generated by a form removal operator.
A correction by the reference area can be applied in the signal flow.
The result is the scale-limited surface (S-F surface according to ISO 25178-2:2021, 3.1.7).

ISO/DIS 25178-607:2026(en)
[9]to[41]
A number of different confocal arrangements have been developed and published in literature .
A.3 Typical laser-scanning confocal microscope (LSCM) configuration
In a laser-scanning confocal microscope, the illumination and detection pattern consist of two single
pinholes placed on optically conjugate planes. The beam emerging from the illumination pinhole is scanned
in a raster manner across the sample in order to build up a confocal image point by point. Figure A.1 shows a
typical configuration of a LSCM. A laser beam illuminates a pinhole PT. The image of the pinhole is formed on
the sample placed in the focal plane of the objective O. The light reflected or backscattered from the sample
passes back through the objective and is imaged onto a second pinhole PR called the confocal aperture.
A detector D at the rear of the confoc
...