Overview
ISO 80000-7:2019 - Quantities and units - Part 7: Light and radiation specifies names, symbols, definitions and SI units for quantities used in light and optical radiation covering the wavelength range of approximately 1 nm to 1 mm. Prepared by ISO/TC 12 in collaboration with IEC/TC 25, this second edition (2019) replaces the 2008 edition and includes simplified quantity tables, clarified definitions, and appropriate conversion factors where applicable.
Key topics and technical scope
- Scope and structure
- Standardizes radiometric, photometric and photon-related quantities (e.g., radiant energy, radiant flux, intensity, radiance) and their spectral counterparts.
- Provides a consolidated Table 1 of quantities, symbols, definitions and units used for optical radiation.
- Representative quantities covered
- Speed of light in a medium and refractive index (including complex refractive index and refractivity).
- Radiant energy, spectral radiant energy, radiant flux (power) and spectral flux.
- Radiant intensity, spectral intensity, radiance and spectral radiance.
- Radiant energy density and spectral densities (wavelength, frequency, wavenumber representations).
- Spectral reference systems and relationships
- Defines spectral quantities with reference to frequency, angular frequency, wavelength (vacuum/medium) and wavenumber, and gives the relationships and conversion factors between these representations.
- Vision-specific quantities
- Photopic, scotopic and mesopic quantities are described, including reference to standard luminous efficiency functions (V(λ), V′(λ), mesopic functions) used for human-vision weighting.
- Units and notation
- Emphasizes SI units (steradian retained in photometry/radiometry) and use of subscripts (e, v, p, mes) to distinguish energetic, visible and photon measures.
Practical applications
ISO 80000-7:2019 is essential for:
- Calibrating and specifying optical instruments (spectrometers, radiometers, photometers, imaging sensors).
- Writing technical specifications and datasheets for LEDs, lamps, displays and lighting systems.
- Metrology laboratories standardizing measurements of radiance, irradiance, flux and spectral distributions.
- Research in optics, remote sensing, spectroscopy, vision science and photobiology where consistent definitions and unit usage are critical.
- Regulatory and standards documentation that requires consistent, SI‑based optical quantity definitions.
Who should use this standard
- Metrologists, optical and illumination engineers, instrument manufacturers, test laboratories, researchers, standards developers, and technical authors preparing specifications or calibration procedures.
Related standards and references
Keywords: ISO 80000-7:2019, quantities and units, light and radiation, radiometry, photometry, spectral radiance, refractive index, SI units, optical radiation standard.
