ISO 9211-2:2024

Overview

ISO 9211-2:2024 - Optics and photonics - Optical coatings - Part 2: Optical properties - defines how to specify and represent the spectral optical properties of coatings (excluding ophthalmic spectacles). The third edition standardizes numerical and graphical rules for spectrophotometric characterization, measurement recording, and the minimum optical-property information (transmittance, reflectance, absorption, optical density, phase change, etc.) needed when specifying coatings for optical systems.

Key topics and requirements

• Optical properties to specify: τ(λ), ρ(λ), α(λ) (or T(λ), R(λ), A(λ)), D(λ), ΔΦ(λ). Polarization and refractive indices of incident/emergent media must be given when angle of incidence ≠ 0°.
• Measurement conditions: Follow ISO 15368, ISO 19962 or equivalent; record angle(s) of incidence, polarization state, spectral range, bandwidth, instrument method and, when relevant, temperature.
• Numerical specification rules: Use inequality format (lower ≤ property ≤ upper) with wavelength and angle ranges. Use subscripts “ave” or “avg” for spectral averages. Arrows (→) indicate linear change of limit across a spectral band.
• Graphical representation rules: Abscissa = wavelength (nm/µm) or wavenumber; ordinate = optical property values. Show upper/lower tolerance bands (hatched areas) or mark single-wavelength limits with triangles. Multiple spectral regions may be combined; different scales are permitted.
• Principal optical functions: Standardized graphical/numerical conventions are provided for Reflecting (RE), Antireflecting (AR), Beam splitting (BS), Attenuating (AT), Filtering (FI), Selecting/Combining (SC), Polarizing (PO), Phase changing (PC), and Absorbing (AB) functions.
• Defaults and clarifications: Default wavelength unit = nm; added symbols (T, R, A) and clarified definitions for average spectral characteristics in this edition.

Applications

• Writing procurement specifications and acceptance criteria for optical coatings used on mirrors, filters, beam splitters, polarizers, phase plates and absorbers.
• Quality control and inspection: defining pass/fail numerical limits and tolerance bands for spectral measurements.
• Optical design and system integration: documenting expected spectral behavior (reflectance/transmittance/phase) across angles and polarizations.
• Test labs and metrology: standardizing measurement reporting so results are comparable between suppliers and customers.

Who uses this standard

• Coating manufacturers and process engineers
• Optical designers and systems engineers
• Test and calibration laboratories
• Procurement/specification engineers and quality assurance teams

Related standards

• ISO 9211-1 - Vocabulary for optical coatings
• ISO 15368 - Measurement of reflectance/transmittance
• ISO 19962 - Spectroscopic measurement methods for integrated scattering

Keywords: ISO 9211-2:2024, optical coatings, optical properties, spectrophotometric characterization, reflectance, transmittance, absorption, spectral specification, optics and photonics.