ISO 9211-1:2024

Overview

ISO 9211-1:2024 - Optics and photonics - Optical coatings - Part 1: Vocabulary is the fourth edition of the international vocabulary for optical coatings. The standard defines uniform terminology for surface treatments (excluding ophthalmic spectacles) produced by applying optical coatings. It provides a standard form for specification, identifies general characteristics, and references test and measurement methods where necessary - but it does not prescribe coating process methods.

Key topics and technical scope

ISO 9211-1:2024 groups terms into four main classes:

• Terms and definitions (basic optics and surface-treatment vocabulary such as clear aperture, rim, witness sample, incident/emergent medium).
• Designations of coatings by function (reflecting, antireflecting, beam‑splitting, attenuating, filtering, polarizing, phase‑changing, absorbing, and supplementary functions).
• Definitions of common coating imperfections (point‑like, line‑like, area‑like, volume‑like imperfections; Annex A contains micrographs).
• Other definitions related to optical properties, polarization and phase.

Key technical concepts defined or clarified include:

• Spectral transmittance, reflectance and absorptance and their interrelationship (τ(λ), ρ(λ), α(λ)).
• Spectral optical density D(λ) and its relation to transmittance.
• Average spectral values over wavelength or wavenumber (how to compute average transmittance/reflectance/absorptance).
• Polarization terms (linear polarization, S‑ and P‑polarization) and refractive index n(λ).
• Test and measurement references where applicable; normative references include ISO 11145 and ISO 80000‑7; imperfections testing is covered in ISO 14997.

The 2024 revision adds definitions and clarifications such as the spectral optical density and explanations for spectral averaging notation.

Practical applications and who uses it

ISO 9211-1:2024 is essential for:

• Optical designers and system engineers specifying coatings for lenses, mirrors, filters and beam splitters.
• Coating manufacturers and suppliers creating product datasheets and witness‑sample protocols.
• Quality assurance and test laboratories performing spectrophotometric and scattering measurements.
• Procurement and contract teams writing unambiguous specifications for optical components.
• Standards committees and educators using a common vocabulary to avoid miscommunication.

Practical uses include preparing technical specifications, interpreting spectral data (transmittance, reflectance, optical density), classifying coating functions, and reporting coating defects consistently.

Related standards

• ISO 9211 series (other parts of optical coatings)
• ISO 11145 (lasers vocabulary)
• ISO 80000‑7 (light and radiation quantities)
• ISO 14997 (surface imperfection test methods)

For the full text and the list of parts in the ISO 9211 series, see the ISO website (www.iso.org).