ISO 22576:2020

INTERNATIONAL ISO
STANDARD 22576
First edition
2020-04
Optics and photonics — Optical
materials and components —
Specification of calcium fluoride used
in the infrared spectrum
Optique et photonique — Matériaux et composants optiques —
Spécification de fluorure de calcium utilisé dans le spectre infrarouge
Reference number
©
ISO 2020
© ISO 2020
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ii © ISO 2020 – All rights reserved

Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Tolerances . 2
4.1 Refractive index variation. 2
4.2 Optical homogeneity (homogeneity of refractive index) . 3
4.3 Bubbles and inclusions . 3
5 Indications . 3
Annex A (informative) The nominal refractive index of calcium fluoride . 4
Bibliography . 5
Foreword
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iv © ISO 2020 – All rights reserved

Introduction
This document applies to the classification of calcium fluoride used in the infrared spectrum.
Calcium fluoride is used for infrared optical systems such as optical windows and lenses. The
specifications for its use in the infrared spectrum are different than those used in the visible range.
The crystal structure of calcium fluoride is referred to as the fluorite structure. A single crystal of
calcium fluoride is composed of the crystal lattice with no grain boundaries. The birefringence of the
crystal depends on the light propagation direction with respect to the crystal axis.
INTERNATIONAL STANDARD ISO 22576:2020(E)
Optics and photonics — Optical materials and components
— Specification of calcium fluoride used in the infrared
spectrum
1 Scope
This document specifies calcium fluoride used in the infrared spectral range from 0,78 µm to 10 µm.
The material specified in this document can also transmit light in other spectral domains (ultraviolet
and visible).
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 10110-18, Optics and photonics — Preparation of drawings for optical elements and systems — Part 18:
Stress birefringence,
...