Meaning
International metrology standards defining nominal characteristics and calibration methods for coherence scanning interferometers specify performance criteria for non-contact areal surface texture measuring instruments. Compliance with ISO 25178-604 allows quality laboratories to characterize topographies of optical mould inserts and precision polymer components using white light interferometry. Standardized protocols define noise levels, flatness deviation limits, and lateral resolution capabilities.
Standardized calibration routines guarantee traceable surface roughness measurements across manufacturing facilities.
Coherence Scanning
Light source coherence length determines vertical scanning resolution across steep surface slopes on micro-moulded plastic lenses. Calibration procedures under ISO 25178-604 evaluate fringe visibility and signal contrast during vertical scanner translation. Optical objective quality dictates signal quality on highly reflective or transparent polymer substrates.
Phase mapping algorithms process interference patterns into height maps.
Noise Floor
Instrument measurement background noise establishes the lower limit for detectable surface roughness parameters like Sa and Sz. Adhering to ISO 25178-604 quantifies structural vibrations and sensor noise that distort surface micro-topography readings. Environmental isolation tables reduce ambient low-frequency vibration. Low noise floors enable reliable sub-nanometer surface roughness measurement.
Calibration Standard
Certified reference surfaces with calibrated step heights verify vertical scale linearity across total measurement ranges. Requirements within ISO 25178-604 govern traceably measured step height targets used for interferometer z-axis calibration. Step height standards ensure accurate depth readings on micro-channel mould cavities.
Traceable standards satisfy industrial quality audit requirements.
