The main purpose of the present work is to establish various types of polarization angles (Brewster angles) and investigate conditions at which they exhibit ideal properties. The polarization angles define the features of relationships between the polarization angles PSI and DELTA and the incidence angle fi0  of the light beam, which allows one to draw certain conclusions on the general properties of both single- and multi-layered systems. Analysis of the experimental relationships PSI(fi0) and DELTA(fi0) based on the theoretical results of this work gives very important information for solving the inverse problem of ellipsometry and other problems.