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The angular dependence of the reflectance from an absorbing randomly oriented polydomain medium consisting of domains either small or large compared with the wavelength is investigated. Besides the two conventional cases, where the refractive index of the incidence medium is either smaller or larger than the averaged index of refraction (small-domain limit) or every principal index of refraction of the domains (large-domain limit), we also discuss a third principal case, which exists only in the large-domain limit. In this third case, only one of the principal indices of refraction is larger than that of the incidence medium, while the averaged index of refraction is smaller. Thus, in contrast to the small-domain limit, total reflection is completely suppressed even in the absence of absorption. A characteristic property of such a polydomain medium is its ability to considerably depolarize linear polarized light in spite of being optically isotropic. Additionally, the parallel polarized reflectance Rp can exceed the perpendicular polarized reflectance Rs over certain angle of incidence ranges. Absorption decreases these domain-size-dependent properties, even under the assumption of constant anisotropy. Nevertheless, for materials with low absorption indices, these effects can affect the optical properties significantly.

We investigate the angular dependence of the reflectance from an isotropic medium consisting of optically large and anisotropic, randomly oriented domains, assuming a highly refractive, isotropic, and homogeneous incidence medium, which is presumed to have a higher refractive index than any of the domains' principal indices of refraction. By employing average reflectance and transmittance theory, we are able to show that the onset of total reflection is considerably shifted to higher angles of incidence compared with an isotropic medium with domains that are small compared with the wavelength. The onset of total reflection for a random medium with large domains is found to be dependent only on the largest principal index of refraction of the domains, assuming that all domains have the same optical properties. Therefore the shift of the onset depends on the magnitude of the optical anisotropy of the domains. Even in the case of a small optical anisotropy, large cross-polarization terms are predicted in the vicinity of the onset of total reflection. These terms show a pronounced maximum near that onset and extend beyond it.

The angular dependence of the reflectance from an isotropic medium with large, randomly oriented, ordered domains is investigated and compared with that of an isotropic medium in which the optical properties can be characterized by a scalar dielectric function. Employing average reflectance and transmittance theory, we demonstrate that an isotropic medium consisting of optically large ordered domains exhibits only a parallel-polarized reflectance minimum, not the formal zero expected at Brewster's angle. We attribute this result to the existence of nonzero cross-polarization terms despite the random orientation and the application of an incoherent averaging scheme, which is used to mimic traditional light sources.