Surface roughness is a measure of how smooth or rough a surface is
With a surface roughness meter, the profile of the surface is analyzed over a predetermined reference length of the object. Usually, the measurement is repeated over different parts of the area to be measured.
The registered surface roughness profiles are converted into different surface roughness figures such as:
Ra : Arithmetic median of surface deviation - Average deviation
Ry : Max Height - The difference between the deepest valley and the highest peak
Rz : Ten-Point Mean Roughness - Average height between five peaks and valleys