What is surface roughness?
Roughness
Surface roughness, often shortened to roughness, is a
component of surface texture. It is quantified by
the deviations in the direction of the normal
vector of a real surface from its ideal form. If
these deviations are large, the surface is rough;
if they are small, the surface is smooth.
Surface roughness depends on the wavelength of the
incoming radiation. If the wavelengths are much
smaller than the surface variations or the
particle sizes that make up the surface, the
surface will look more rough. For example, finegrained
sand would appear fairly smooth to long
wavelength microwaves but would appear quite
rough to the visible wavelengths.