In optical interferometry diffuse reflectivity of the surface under st
udy should be high and homogeneous. Application of a white reflective
coating can strongly improve measurement results. The optical properti
es of bronze powder, TiO2 powder, white Chinese ink, and MgO coatings
are discussed. Measurements of reflected intensity distribution show t
hat white Chinese ink and MgO have superior optical characteristics, a
nd electron microscopy shows that these coatings cause thickness artif
acts of less than 7.5 and 17 mu m, respectively. The effect on deforma
tion measurements is demonstrated by moire topography on a thin membra
ne that is deformed under small static pressures. The membrane center
displacement varies from 15 to 100 mu m, and within a measuring precis
ion of 2.5 mu m no artifacts on this deformation are found. (C) 1997 O
ptical Society of America.