Overview
EN ISO 25178-603:2025 - titled "Geometrical product specifications (GPS) - Surface texture: Areal - Part 603" - defines the design and metrological characteristics of phase shifting interferometry (PSI) instruments used for areal measurement of surface topography. Published by CEN and identical to ISO 25178-603:2025, this second edition updates and supersedes the 2013 version and clarifies requirements for PSI instruments used to measure optically smooth surfaces. Because areal data can be used to extract profiles, the guidance is also applicable to profiling measurements.
Key topics and technical requirements
- Scope and purpose: Specification of design features and metrological characteristics for non-contact PSI instruments for areal surface texture measurement.
- Instrument requirements (Clause 4): Summarizes normative features and an information-flow concept for measurement systems.
- Metrological characteristics (Clause 5): Defines the measurement properties that users and manufacturers must consider (e.g., uncertainty sources, measurement performance metrics) and links to ISO 25178-600 for metrological definitions.
- Design features (Clause 6): Clarifies instrument configurations relevant to PSI, including microscope-based interference objectives and larger-field interferometer designs.
- Terms and definitions (Clause 3): PSI method, linear and sinusoidal PSI, PSI algorithms, and the equivalent wavelength (λeq) are defined to ensure consistent terminology across the ISO 25178 series.
- Informative annexes:
- Annex A - Principles of PSI instruments for areal topography measurement.
- Annex B - Sources of measurement error and their relationship to metrological characteristics.
- Annex C - Relationship to the GPS matrix model and other GPS standards.
Applications and users
- Who uses this standard:
- Manufacturers of optical areal surface topography instruments and PSI systems.
- Metrology laboratories and calibration facilities developing measurement procedures.
- Quality engineers, R&D teams, and researchers working on surface texture characterization.
- Accreditation bodies and standards committees referencing GPS requirements.
- Practical applications:
- Characterizing microscale surface finishes in optics, semiconductor wafers, medical devices, and precision engineering parts.
- Supporting traceable areal texture measurements and extracting profile data for quality control.
- Informing instrument design choices, uncertainty assessment, and error mitigation strategies.
Related standards
- ISO 25178-600 - Metrological characteristics for areal topography measuring methods (normative reference).
- ISO 25178 series - Other parts for areal surface texture specification.
- ISO 14638, ISO 8015, ISO 14253-1 - GPS framework, decision rules and matrix model referenced for consistency.
- ISO/TR 14999-2 - Provides additional background on synchronous detection and PSI.
This standard is essential for ensuring consistent, traceable areal surface texture measurements using phase shifting interferometry (PSI) and for integrating PSI instrument design with the ISO GPS framework.