ISO 25178-607:2019

Overview

ISO 25178-607:2019 - "Geometrical product specifications (GPS) - Surface texture: Areal - Part 607" defines the nominal characteristics and influence quantities of confocal (non-contact) microscopy instruments used for areal surface topography measurement. The standard describes how confocal microscopes form optically sectioned images during axial scans, how those stacks are converted into areal topography (and derived profiles), and which instrument and sample factors affect metrological performance.

Key topics and requirements

• Scope and intent: Specifies instrument characteristics and influence quantities for confocal microscopy systems for areal surface texture; methods also apply to profile measurements extracted from topography images.
• Terminology and definitions: Formal definitions for terms such as confocal microscopy, axial scan, axial response, FWHM (full width at half maximum), confocal stack, confocal topography image, and confocal peak location algorithm.
• Influence quantities: Identifies key factors that affect measurement results, including:
  • optical parameters (wavelength, bandwidth, numerical aperture, magnification, optical aberrations),
  • imaging and acquisition settings (axial scan length, axial steps, axial scanning rate, integration time, camera pixel spacing and lateral sampling),
  • signal processing (confocal peak location algorithm, flatness calibration),
  • environmental and instrument factors (noise, vibration, tilt, lateral distortion, illumination uniformity),
  • sample interactions (complex refractive index, film thickness, under-resolved features, maximum measurable local slope).
• Metrological mapping: Provides a matrix relating influence quantities to metrological characteristics (as in ISO 25178-600), aiding evaluation of measurement uncertainty and instrument suitability.
• Informative annexes: Coverage of in-plane scanning classifications (Annex A), confocal theory of operation (Annex B), effects of thin/thick films (Annex C), and relation to the GPS matrix model (Annex D).

Practical applications and users

Who uses ISO 25178-607:

• Instrument manufacturers - to specify design limits and declared performance of confocal microscopes.
• Calibration and QA laboratories - to assess instrument characteristics, perform flatness calibration, and document measurement influence factors.
• Metrologists and surface texture analysts - to interpret areal topography data, select acquisition settings, and estimate measurement uncertainty.
• R&D and production engineers in industries such as precision machining, optics, coatings, semiconductors, medical devices and tribology - when non-contact areal surface measurements are required.

Practical uses:

• Selecting and comparing confocal microscopy systems for areal surface texture measurement.
• Setting acquisition parameters (axial steps, scan length, integration time) consistent with measurement objectives.
• Understanding how sample properties (films, refractive index) and instrument geometry affect topography results.

Related standards

• ISO 25178 series (areal surface texture standards), notably ISO 25178-600 (metrological characteristics) and ISO 25178-602 (confocal probe arrangements).
• ISO 14638 (GPS matrix model), ISO 8015 (fundamental GPS rules), ISO 14253-1 (decision rules for verification).

Keywords: ISO 25178-607:2019, confocal microscopy, areal surface texture, surface topography, non-contact instruments, metrological characteristics, axial scan, confocal peak algorithm.