Optical Profilometry
Optical profilometry is a non-contact surface metrology method that measures 3D surface topography—roughness, texture, step height, flatness, and form—by analyzing light instead of touching the part. It uses white light interferometry, confocal, focus variation, or structured light to generate areal height maps and ISO 25178 parameters like Sa. Ideal for precision machined, coated, or delicate surfaces.
In a CNC machining or millwork QC workflow, optical profilometry is called on when a single-line roughness trace isn't enough. After grinding, polishing, or finishing, the profiler scans a flat or textured area and produces a 3D height map, letting the shop check Sa and other areal parameters against print. Because it never contacts the part, it's safe for coated, soft, or mirrored surfaces that a stylus could scratch. It also reveals local defects, small steps, and microtexture that contact probes miss. On the floor, it is used to validate toolpaths, monitor tool wear, confirm lamination or edge-banding quality, and support process optimization. High-end systems resolve sub-micron vertical features, making them useful for precision optics, MEMS, and critical machined surfaces. The payoff is faster, non-destructive inspection and better decisions on finish acceptance, process capability, and rework.
Is optical profilometry the same as stylus profilometry?
No. Optical profilometry is non-contact and typically produces areal 3D data. Stylus profilometry uses a physical tip and is generally line-based, which can suit legacy roughness specs but risks surface interaction and misses full-area texture detail.
What surface parameters does it support?
Common outputs include roughness, texture, step height, contour, flatness, form, and microstructure metrics, with some systems also supporting defect detection, thickness, and GD&T-related geometry depending on the platform.
When is it preferred on machined parts?
It is preferred for non-destructive inspection of sensitive or precision surfaces, especially when areal texture, micro-defects, or submicron steps matter more than a single trace roughness value.