profilometry

Profilometry is the set of techniques used to measure the surface topography of a material, capturing the variation of height across a line (1D) or over an area (2D/3D). A profilometer produces a profile or a topographic map that reveals roughness, waviness, step heights, and texture.

Profilometry methods are broadly categorized into contact and non-contact approaches. Contact profilometers use a stylus that physically traces the surface, yielding a height profile as the stylus moves. Non-contact methods use optical or other sensing principles to infer height without touching the surface, reducing the risk of damage or contamination.

Common optical techniques include laser triangulation, confocal microscopy, interferometry (coherence scanning and white-light), and structured-light or fringe projection. In all cases, results may be reported as roughness parameters (mean roughness Ra, root-mean-square Rq), waviness, peak-to-valley height, and areal measurements defined by ISO standards.

Applications span manufacturing and process control in optics, metalworking, semiconductors, and additive manufacturing. Profilometry provides quality control data, informs surface engineering decisions, and characterizes coatings or texture. Data are typically presented as height maps, 2D profiles, or 3D topography with color scales and statistical summaries.

Trade-offs exist between techniques: contact measurements can be robust on some surfaces but risk damage or wear, while non-contact methods may be sensitive to reflectivity or surface gloss. Calibration, traceability, and appropriate scale selection are essential, with standards such as ISO 4287, ISO 4288 (stylus roughness), and ISO 25178 for areal surface characterization guiding practices.