ISO 25178-700:2022

Overview

ISO 25178-700:2022 - "Geometrical product specifications (GPS) - Surface texture: Areal - Part 700" defines generic, traceable procedures for the calibration, adjustment and verification of areal topography measuring instruments. It specifies default methods for establishing the metrological characteristics common to areal instruments (as referenced in ISO 25178-600) and is intended to support reliable measurement, uncertainty evaluation and comparability between systems. The document focuses on instrument-level, instrument-agnostic procedures; instrument-specific issues (for example, arcuate probe motion) are covered elsewhere (e.g., ISO 25178-701). Area‑integrating techniques such as light scattering are excluded.

Key Topics and Technical Requirements

• Calibration procedures and verification using material measures traceable to national metrology institutes (ISO/IEC Guide 99).
• Reporting of measurement conditions and handling of environmental or operational influence quantities.
• Handling of missing points, spurious data and outliers to ensure robust topography data.
• Determination and specification of core metrological characteristics, including:
  • Measurement noise (N) and instrument noise (NM) and methods to estimate them (filters, material measures).
  • Flatness deviation evaluation and calibration.
  • z-axis amplification coefficient (αz) and z-linearity deviation across scan ranges.
  • x- and y-axis amplification coefficients (αx, αy) and mapping deviation Δ(x,y).
  • Perpendicularity of the z-axis with respect to the x–y areal reference.
  • Topographic spatial resolution (R) and Instrument Transfer Function (ITF) for lateral resolution limits.
  • Topography fidelity (FI) and the small‑scale fidelity limit (FIL), including slope‑dependent effects.
• Default measurement volumes, material measures and procedures are defined; alternative traceable techniques are acceptable when justified.

Practical Applications and Users

ISO 25178-700 is practically valuable for:

• Calibration and accredited metrology laboratories establishing traceable calibration services for areal instruments.
• Manufacturers of optical and tactile areal topography instruments implementing factory calibration and verification.
• Quality, R&D and production engineers in industries where surface texture matters: automotive, aerospace, precision machining, semiconductor, coatings, tribology and surface engineering.
• Metrologists and conformity assessors seeking comparable measurements, validated instrument performance and defensible measurement uncertainty budgets.
• Users adapting areal methods to profile measurements (many procedures are adaptable for profiling instruments).

Benefits include improved measurement comparability between different systems and manufacturers, clearer uncertainty evaluation, and standardized procedures to support product specification and quality control.

Related Standards

• ISO 25178 series (areal surface texture)
• ISO 25178-600 (metrological characteristics)
• ISO 25178-701 (mechanical probing specifics)
• ISO 14638, ISO 8015, ISO 14253-1 and ISO/IEC Guide 99 (traceability and GPS framework)

Keywords: ISO 25178-700, areal topography calibration, surface texture calibration, measurement noise, z-linearity, topography fidelity, instrument transfer function.