Overview
SIST EN ISO 25178-606:2026 focuses on the geometrical product specifications (GPS) for areal surface texture measurement, specifically addressing non-contact (focus variation) instruments. This standard outlines the design and characteristics of instruments using focus variation technology to achieve precise, reliable measurement of surface topography. Applicable to systems using no pattern illumination or fixed pattern illumination, the document provides the framework for manufacturers, laboratories, and quality control professionals to ensure consistent surface measurements and instrument development.
Focus variation instruments enable high-resolution, non-invasive areal mapping of surface features across a wide range of materials. As surface quality becomes increasingly important in industries such as automotive, aerospace, and medical device manufacturing, adhering to recognized standards like ISO 25178-606 improves both measurement reliability and global interoperability.
Key Topics
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Scope and Applicability
- Defines requirements for focus variation instruments used in areal surface topography measurement.
- Applicable to measurements performed without pattern illumination or with fixed pattern illumination (excluding varying pattern illumination methods).
- Surface profiles can be extracted from areal data, allowing for profiling applications as well.
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Instrument Design and Performance
- Specifies essential components and expected functions of focus variation systems:
- Optical components (lenses, detectors, objectives)
- Illumination systems (coaxial, ring light, fixed pattern)
- Axial scanner for controlled movement along the optical axis
- Focus measurement algorithm to process image sharpness data
- Emphasizes metrological characteristics in accordance with ISO 25178-600.
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Measurement Principles and Algorithms
- Focus variation utilizes the change in image sharpness during an axial scan to determine surface heights.
- Describes the generation and analysis of focus information curves for accurate topography mapping.
- Highlights the role of polarization and illumination choices on measurement capability and accuracy.
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Sources of Error and Limitations
- Identifies key influence quantities affecting measurements: illumination, numerical aperture, instrument noise, environmental vibration, lateral resolution, and sampling interval.
- Notes limitations, such as reduced measurement capability on highly transparent or extremely smooth surfaces unless fixed pattern illumination is used.
Applications
Related Standards
- ISO 25178 Series: Comprehensive family covering GPS - Surface texture: areal measurement methods, instrument characteristics, and calibration.
- ISO 25178-600: Metrological characteristics for areal topography measuring methods.
- ISO 25178-700: Procedures for determining metrological characteristics.
- ISO 25178-607: Further specifications for methods related to axial scanning.
- ISO 14638: Provides the GPS matrix model, including the relationship and integration of areal measurement standards.
- ISO 8015: Fundamental rules of GPS, applied across standards for product specification and verification.
- ISO 14253-1: Decision rules for product specification conformity.
Understanding and applying ISO 25178-606:2026 is essential for organizations seeking best practices in areal surface texture measurement using non-contact focus variation instruments, ensuring measurement accuracy, process efficiency, and compliance with international metrology standards.
