ISO 11421:2025
(Main)Optics and photonics — Uncertainty of optical transfer function (OTF) measurement
Optics and photonics — Uncertainty of optical transfer function (OTF) measurement
This document gives general guidance on evaluating the sources of error in optical transfer function (OTF) equipment and in using this information to estimate errors in a measurement of OTF. It also gives guidance on assessing and specifying a general uncertainty for a specific measuring equipment, as well as recommending methods of routine assessment. The main body of this document deals exclusively with the modulation transfer function (MTF) part of the OTF. The phase transfer function (PTF) is dealt with relatively briefly in Annex A.
Optique et photonique — Incertitude de mesurage de la fonction de transfert optique (OTF)
La présente Norme internationale donne des indications générales sur l'évaluation des sources d'erreur dans un matériel de fonction de transfert optique ainsi que sur l'utilisation de cette information afin d'estimer les erreurs de mesurage de l'OTIF. Elle donne également des indications sur l'appréciation et la spécification d'un schéma de précision générale d'un matériel de mesurage spécifique, ainsi que des méthodes de recommandation d'une évaluafion de routine.Le corps principal de la présente Norme internationale traite exclusivement de la partie fonction de transfert de modulation (MTF) de l'OTF. La fonction de transfert de phase (PTF) est traitée assez brièvement dans l'annexe A.
General Information
Relations
Standards Content (Sample)
International
Standard
ISO 11421
Second edition
Optics and photonics — Uncertainty
2025-11
of optical transfer function (OTF)
measurement
Optique et photonique — Incertitude de mesurage de la fonction
de transfert optique (OTF)
Reference number
© 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
Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms, definitions and symbols . 1
3.1 Terms and definitions .1
3.2 Symbols .2
4 Sources of uncertainty in measuring equipment. 3
4.1 General .3
4.2 Geometry of optical bench system .4
4.2.1 General .4
4.2.2 Finite object and image distance .4
4.2.3 Infinite object distance and finite image distance .5
4.2.4 Infinite object and image distance .6
4.2.5 Suppression of image distance errors by refocusing .6
4.2.6 Mounting of test piece .6
4.3 Azimuth changing .7
4.3.1 General .7
4.3.2 Finite object and image distance .7
4.3.3 Infinite object distance and finite image distance .7
4.3.4 Infinite object and image distance .7
4.3.5 Suppression of image distance errors by refocusing .7
4.4 Alignment (orientation) of TTU and image analyser .7
4.5 Correction factors .8
4.5.1 General .8
4.5.2 Slit width errors .9
4.5.3 Correction for MTF of incoherently coupled relay lenses .9
4.5.4 Spatial frequency correction for field angle .9
4.5.5 Off-axis magnification errors due to image distortion using grating objects .10
4.6 Image distance error .10
4.7 Spatial frequency errors .11
4.8 Residual aberrations in relay optics . .11
4.9 Spectral characteristics.11
4.10 Extent of test target and/or scan and/or camera detector .11
4.11 Angular response characteristics of image analyser . 12
4.12 Polar luminance/radiation characteristics of object generator . 12
4.13 Signal and data processing . 12
4.14 Stray radiation . 12
4.15 Coherent radiation . 12
4.16 Baseline error . 12
4.17 Linearity of camera detector . 13
5 Methods of assessing measurement errors .13
5.1 General . 13
5.2 Geometry of optical bench system . 13
5.2.1 Straightness of slideways . 13
5.2.2 Parallelism of surfaces and/or perpendicularity to reference axes .16
5.2.3 Errors of rotation angles .17
5.3 Collimation error (departure from infinite object distance) .18
5.4 Image distance setting . 20
5.5 Spectral characteristics.21
5.6 Extent of target and/or scan and/or camera detector . 22
5.7 Signal and data processing . 22
5.8 Polar response to image analyser. 22
iii
6 Calculation of overall uncertainty of a measurement .23
7 Specifying a general equipment uncertainty .24
7.1 General .24
7.2 Nominal uncertainty value (NUV) .24
7.3 Standard-lens measurements (SLM) . 25
7.4 Audit-lens measurements (ALM) . 25
7.5 Slit aperture test (SAT) . 26
8 Routine performance evaluation .26
Annex A (normative) Uncertainty of PTF measurement.27
Annex B (informative) Determination of rate of change of MTF with various parameters .29
Annex C (informative) Example calculation of NUV .32
Bibliography .44
iv
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
...
Questions, Comments and Discussion
Ask us and Technical Secretary will try to provide an answer. You can facilitate discussion about the standard in here.