3D measurement of polished surfaces

Nobody would need any experiences or equipment to see the differences on the following steel surfaces. Both reflect the light in an shine way but the gloss level is significant different.

Specification and quality control are complicated. Even expensive surface standards as the KNT 4058 from Halle have already a big uncertainty (here +-9% for Ra, Rz and Rmax).

Sample 1:

Sample 2 - with higher gloss:

In contrary to statistics of multiple lines or 3d parameter (Svk) single profiles are not suitable for an significant characterization of the surfaces. The measurement was done using the smartWLI compact with an 50x objective which provides the necessary 3d resolution for the finest structures of the polished surface (app. 100 mio. measuring points).