EN ISO 25178-606:2026

Overview

EN ISO 25178-606:2026 outlines the design and technical characteristics of non-contact focus variation instruments used for areal surface topography measurement. Developed by CEN and ISO, this standard serves as a vital part of the Geometrical Product Specifications (GPS) series, ensuring accurate and reliable measurement of surface texture. The document applies to focus variation methods employing no pattern illumination or fixed pattern illumination, supporting a wide range of industrial and research applications where precise, non-contact surface analysis is essential.

By setting clear requirements for focus variation instruments, EN ISO 25178-606:2026 enhances the consistency and comparability of surface measurements. This makes it easier for users to select, calibrate, and operate these instruments for both areal and profiling measurements, ultimately supporting high-quality manufacturing and research processes.

Key Topics

• Focus Variation Principle
  Defines focus variation as a non-contact optical method for measuring areal surface topography using image sharpness at various focal depths.
• Instrument Components
  Specifies required components, including sensors, optics, illumination systems (with or without fixed pattern), axial scanners, and measurement algorithms.
• Measurement Algorithms
  Discusses approaches for analyzing image sharpness to calculate surface heights, ensuring the conversion of raw image data into accurate 3D surface information.
• Metrological Characteristics
  Outlines the measurement noise, spatial resolution, linearity, and influence of environmental factors and light sources on measurement accuracy.
• Design Features
  Highlights key aspects, such as the use of polarization filters, objective lenses, and the importance of long working distances and high numerical aperture for optimal performance.
• Influence Quantities and Error Sources
  Identifies primary sources of measurement error, including vibrations, instrument noise, optical distortion, and sampling intervals.

Applications

EN ISO 25178-606:2026 is applicable to organizations and labs engaged in:

• Quality Control and Assurance
  Accurately measuring surface characteristics in manufacturing, ensuring compliance with specifications for automotive, aerospace, medical devices, and electronics industries.
• Material and Surface Research
  Precise assessment of coating thickness, roughness, and topography in R&D environments.
• Process Optimization
  Improving machining, fabrication, and finishing processes by monitoring surface features using advanced non-contact metrology.
• Reverse Engineering
  Supporting detailed surface reconstructions for replicating or improving existing products.
• Calibration and Standardization
  Providing a basis for instrument calibration routines and comparison across different devices or measurement environments.

The standard’s focus on non-contact, optical measurement techniques is especially valuable where contact methods are impractical-such as with delicate, soft, or highly geometrically complex surfaces.

Related Standards

For comprehensive surface texture measurement and GPS, the following standards complement EN ISO 25178-606:2026:

• EN ISO 25178-600: Metrological characteristics for areal topography measuring methods
• EN ISO 25178-607: Design and characteristics of coherence scanning interferometry instruments
• ISO 14638: ISO GPS matrix model-overview of the GPS system
• ISO 14253-1: Decision rules for verification and conformity assessment
• ISO 8015: Fundamental rules of GPS
• ISO 25178 series: Complete family of standards on surface texture: areal methods

Adhering to EN ISO 25178-606:2026 ensures harmonization with global best practices in non-contact areal surface topography measurement, supporting innovation, traceability, and competitiveness in modern manufacturing and metrology.