Overview
ISO 19986:2020 - Lasers and laser-related equipment - Test method for angle resolved scattering (ARS) defines a standardized test method to measure the angular distribution of radiation scattered from optical components. The scope covers coated and uncoated optics, photonic structures and materials that are transparent, translucent or opaque, across wavelengths from 5 nm (EUV) to 15 µm (IR). Results are reported as angle resolved scattering (ARS) and can be converted to BRDF/BTDF/BSDF or integrated to yield Total Scattering (TS).
Key Topics and Requirements
- Measurement principle: ARS is measured by recording scattered radiant power as a function of polar and azimuthal angles using a detector with a finite aperture scanned over the scattering sphere (often via in‑plane detector scans).
- Instrument functional sections: radiation source, beam preparation (spatial filter, attenuator, beam shaping), goniometer/scan mechanics, detection system (detector aperture, field lens), and specimen mount.
- Geometry and origin: spherical coordinates referenced to specimen normal; origin location (entrance/exit surface or specimen) must be documented.
- Wavelength range: applicable from 5 nm (EUV) to 15 µm (IR).
- Environmental control: measurements should be performed in a cleanroom or under laminar flow to minimize dust-induced scatter (referenced ISO 14644‑1).
- Calibration and alignment: procedures, including at least two calibration methods and instrument alignment steps, are specified; a reference channel is required if source drift or fluctuations exceed ~5% during calibration/measurement.
- Data and uncertainty: procedures include ARS determination, conversion to BRDF/BTDF/BSDF, numerical integration to derive TS, and uncertainty considerations for meaningful metrology.
- Documentation: specimen orientation, origin, illumination conditions, angular scan ranges and instrument signature must be recorded.
Applications
- Quality control and acceptance testing of optical components (mirrors, lenses, coated surfaces).
- Characterization of photonic structures, diffraction gratings, display foils and diffusers.
- Stray light and stray‑radiation analysis in optical system design (input for ray- and wave‑based simulations).
- Development and qualification of optics for deep‑UV, EUV and IR applications where scatter limits system performance.
- Research labs and metrology centers performing high‑precision scattering measurements.
Who Should Use It
- Optical manufacturers and coating houses
- Photonics and semiconductor metrology teams
- Laser system designers and optical engineers
- Standards bodies and test laboratories specializing in stray light and surface quality
Related Standards
- ISO 13696 - Total Scattering (TS) measurement methods and definitions
- ISO 11145 - Optics and photonics vocabulary and symbols
- ISO 14644‑1 - Cleanroom classification
- ASTM E2387‑19 and SEMI ME1392 - other ARS measurement references
ISO 19986:2020 provides a practical, standardized framework for consistent, traceable ARS measurements that feed directly into optical design, quality assurance and stray‑light mitigation workflows.