Overview
ISO 25178-605:2014 - Geometrical product specifications (GPS) - Surface texture: Areal - Part 605 - specifies the metrological characteristics of non-contact areal surface texture instruments that use a point autofocus probe (point autofocus optical profilers). This part of the ISO 25178 family defines terms, measurement concepts and influence quantities needed to describe instrument behaviour, performance limits and interpretation of areal surface texture data from point autofocus systems.
Key Topics and Requirements
- Scope and purpose: Describes nominal characteristics for non-contact (point autofocus probe) instruments used for areal and profile surface texture measurement.
- Instrument configuration: Defines the three basic elements - autofocus optical system, autofocus mechanism, and electronic controller - and provides classification of possible set-ups (see Annex A).
- Measurement coordinate system and measurement loop: Standardizes the X, Y, Z axes, the measuring volume and the closed measurement loop concept to support consistent metrology.
- Metrological quantities and response:
- Response curve and amplification coefficients for linearity and correction of measured vs actual quantities.
- Definitions of instrument noise and measurement noise, and guidance on their impact on areal data quality.
- Sampling intervals (Dx, Dy) and digitisation step (Dz) definitions relevant to data resolution.
- Spatial height resolution, lateral resolution, and width limit for full height transmission as measures of an instrument’s ability to resolve surface features.
- Influence quantities: Identification and description of environmental, optical and mechanical factors that affect measurement uncertainty.
- Informative annexes: Practical guidance on spot size and focal shift, beam offset and slope limits, instrument features, and relation to the GPS matrix.
Practical Applications and Who Uses This Standard
ISO 25178-605 is used by:
- Metrology laboratories and calibration houses to assess and report profiler performance.
- Instrument manufacturers to specify, design and validate point autofocus optical profilers.
- Quality engineers and inspection teams in automotive, aerospace, medical device and precision manufacturing for selecting instruments and defining measurement capability.
- R&D teams and surface metrology specialists for method selection, uncertainty analysis and comparing areal surface texture data across instruments.
Practical uses include instrument acceptance testing, defining measurement uncertainty contributors, optimizing sampling and resolution for specific surface textures, and ensuring consistent areal surface texture specifications.
Related Standards
- ISO 25178 series (Parts 1–7, 70–71) - areal surface texture framework
- ISO 25178-601 / -602 / -603 / -604 / -606 - nominal characteristics for other instrument types (stylus, confocal, interferometric, focus variation)
- ISO 25178-701 / -702 / -703 - calibration and measurement standards
Keywords: ISO 25178-605, surface texture, areal, non-contact, point autofocus probe, optical profiler, metrological characteristics, surface metrology, measurement uncertainty, spatial resolution.