A scatterometer is extended and allows us to perform ellipsometric mea
surements on scattered light in each direction of space. Experimental
data are given for single thin-film layers and optical coatings and re
veal unexpected results. The phenomena are investigated by means of th
e electromagnetic theories of surface and bulk scattering that emphasi
ze the role of partial correlation and localized defects. (C) 1996 Opt
ical Society of America