Surface Roughness

• Roughness measurement

 

Plotting surface roughness:

Optical surface roughness profiling using interference microscopy produces a high-precision three dimensional measurement of the surface roughness of many materials. Height precision may be as precise as fractions of a nanometer. Using a wavelength of light as the standard or measurement, surface peaks, valleys and slopes are accurately and repeatably measured using NIST-traceable processes - and without contacting surfaces.

The resulting plot contains reliable linear two dimensional cross-sections in any direction across the surface, and can be used to produce precise calculations of volume inherent in the roughness, including imagery of voids, pits, grooves and scratches, as well as solid displacement, relative surface flatness, average (relative) surface height variations, frequency and placement of peaks, size and shape of plateaus, a texture's departure from the mean, the presence and shape of surface flaws, the accuracy or precision of manufacturing, and so forth.

Surface roughness metrology with a 3D optical profiler has been beneficially used in determining and maintaining quality control in honing and grinding of precision engineered surfaces, because of the virtures of a non-contact surface test. For example, in polishing, honing or grinding processes, successive measurements can be made of the exact same location, to determine the cumulative effect or effectiveness of the finishing process. Researchers and scientists have discovered the value of these recursive surface roughness measurements in determining the efficacy of machining, coating, etching and chemical planarizing processes, as well as optimizing polish, cutting or time and materials.

Sometimes, stylus profilometers have been known alter the roughness of a surface, for example, by rounding peaks. This can prohibit repeat measurement of a specific location, as the subsequent measurement would measure an altered surface structure. Uncertainty of position in repeating measurements in a single location is also reduced with contiguous 3D surface roughness plots.