The engineering calculation methods of complex crystal—optical elements consisting of anisotropic crystals with accidental direction of system compo nents optical axes are developed. The practical results of birefrigent crystal— optical elements ( BCE ) consisted of two one - axes crystals complex resear— ches are given. The BCE analysis and synthesis during propagation and interference of polarised *zaves are involved in researches. We present in report our BCE - based apparatures. Investigations in such directions as laser optical and optoelectronic instruments making, laser optical systems for detection and ranging, communication and information processing call for the development of an optical element base with extended function capabilities. In this connection, of current concern are investigations in the field of analisys and synthesis of complex crystal—optical elements of anisotropic crystals, which have the property of electromagnetic wave splitting into orthogonally polarized components with the possibility of their subsequent control. In this case of particular interest is studiyng interference-polarization properties of anisotropic crystal—opti— cal elements, since it is possible on their basis to propose new methods of optical wave grouping ( heterodyning ) and measuring the degree of radiation coherence as well as to develop new variants of laser interferference systems and devices. The main difficulty in calculation of electromagnetic wave transmission through complex crystal—optical elements consisting of anisotro— pic crystals with random orientation of optical axes in components is the necessity of taking into account the pecularities of extraordinary wave propagation: first, in an anisotropic crystal the vector of energy flux density, that is, a ray is not directed along the wave vector in the general case — meanwhile, it is precisely the ray direction that is directly observed and determined in practice and the basic requirement is the necessity of taking into account tracing of an extraordinary e— ray, that is, calculation of its energy trajectory; second, in the general case the e - ray does not lie in the plane of incidence.