Stylus Profiliometry is the technique that is most commonly used for measuring surfaces. This measurement can be performed in both 2D & 3D. 3D measurement take much longer time than 2D measurement.
The roughness of the surface profile is measured by this method depends upon the radius of the tip and the stylus load. To obtain high resolution measurements a small radius tip is necessary, less than 0.1 μm tip & 1mg load.
White Light Interferometry (WLI):
White light interferometry provides a non-contact method for measuring a surface with a range of magnifications in a much shorter time than the other techniques. But this technique is not used widely because of some limitations. Steep slopes can show additional height, light can be reflected on the surface and no data can be obtained.
Atomic Force Microscopy (AFM):
AFM measurements can have an extremely high resolution compared to other methods. Care must be taken when conducting AFM measurements as external vibrations can have a severe impact on the measurements, as can improper engagement of the tip onto the sample.