Three novel methods for the determination of optical anisotropy are pr
oposed and tested. The first, the special points method, may be applie
d to any uniaxially anisotropic medium and is based on the measurement
of s- and p-polarized light reflectances under near-normal or grazing
angles (or both) and of the Brewster angle. The second method is base
d on the use of the Azzam universal relationship between the Fresnel s
- and p-reflection coefficients. For a flat surface and an isotropic m
edium, the Azzam combination of coefficients becomes zero and thus is
independent of the incidence angle, whereas for a uniaxial or biaxial
anisotropic sample it acquires a certain angular dependence, which may
be used to determine the anisotropy of the sample. Finally, for those
cases in which the anisotropy of the material of a film deposited on
an isotropic substrate is itself of interest, a third method, the inte
rference method, is suggested. This technique makes use of the differe
nt dependences of s- and p-polarized beam optical path-length changes
on the variation of the angle of incidence. (C) 1998 Optical Society o
f America.