optical objective. One portion is reflected from the tested
part and the other from a high quality flat reference.
Interference patterns are formed and all intensities are
directed onto a solid state camera. A MetroPro software was
used to convert the intensities into images. The time of
measurements is very short and the surface topography with
features up to 5 mm height can be determined with a vertical
resolution down to 0.1 nm. Surface characterization, such as
forms, volumes, roughness, step height (film thickness) and
waviness are available. This method was used to characterize
the pattern structure of the coatings and average
roughness (Ra) of the layers is defined as: