ISO 19741:2025

International
Standard
ISO 19741
Second edition
Optics and photonics — Optical
2025-05
materials and components — Test
method for striae in infrared optical
materials
Optique et photonique — Matériaux et composants optiques
— Méthodes d’essai pour déterminer les stries des matériaux
optiques infrarouges
Reference number
© ISO 2025
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ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 1
5 Apparatus . 2
5.1 Apparatus arrangement .2
5.2 Collimating infrared light source system .2
5.3 Projection optical system .2
5.4 Knife edge device .3
5.5 Image sensor . .3
5.6 Computer image collecting, processing and displaying system .3
5.7 Standard grey level sample .3
6 Test conditions . 3
6.1 Environmental temperature .3
6.2 Relative air humidity .3
7 Sample . 3
7.1 Surface roughness .3
7.2 Scratches and digs of surface .3
8 Procedure . 4
8.1 Projection measurement .4
8.2 Schlieren measurement .4
9 Data processing . 5
10 Test report . 5
Annex A (informative) Test record for striae in infrared optical materials . 6
Bibliography . 7

iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
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This document was prepared by Technical Committee ISO/TC 172, Optics and photonics, Subcommittee SC 3,
Optical materials and components.
This second edition cancels and replaces the first edition (ISO 19741:2018), which has been technically
revised.
The main changes are as follows:
— editorial changes throughout the document.
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
International Standard ISO 19741:2025(en)
Optics and photonics — Optical materials and components —
Test method for striae in infrared optical materials
1 Scope
This document specifies the principle, apparatus, condition, sample, procedure and data processing of
measuring striae in infrared optical materials.
It is applicable for the determination of striae in infrared optical materials, such as infrared optical glass,
which is opaque to visible wavelengths and whose transmission optical spectra are beyond 0,78 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 10110-7, Optics and photonics — Preparation of drawings for optical elements and systems — Part 7:
Surface imperfections
ISO 10110-8, Optics and photonics — Preparation of drawings for optical elements and systems — Part 8:
Surface texture
3 Terms and definitions
For the purposes of this document, the following terms and definitions 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
striae
...