Measurement of the small angles of grazing incidence (between the light beam and the surface), &thgr;=&thgr;pand &thgr;=&thgr;s, that are required to decrease the intensity reflectances of a planar surface of an absorbing isotropic medium for the parallel ( p) and perpendicular (s) polarizations, respectively, from 1 (at &thgr;=0) to 1−&ggr;, where &ggr; is a small predetermined reflectance loss (&ggr;≲0.1), permits simple, explicit, and direct determination of both the real and imaginary parts of the complex dielectric function of the medium at the wavelength of the incident monochromatic radiation.