Since each year all are more grown different synthetic crystal since crystals find the most broad using in science and
technology. Obviously, as important efficient and fine methods of the study and analysis crystal, including optical.
The interference pictures play in optical method of the study crystal important role. At imposition two coherent bunches
of the light with alike polarization appears the interference picture - a spatial interleaving maximum and minimum
intensive. If coherent bunch are polarized mutually perpendicular, that interference picture does not appear, but result to
interferences is a light circular or elliptical polarized. For observation of the interferences in this case necessary
polarization interference bunch by means of analyzer to bring about one direction.
The optical scheme is offered for observation conoscopic figures of the unusual type.
They are received interference pictures with light bunch, having small angular divergence in the manner of parallel
stripes, rings, ellipses. Experimental is determined border corner, under which occurs transition from standard
conoscopic figure to quotient case. The optical spottiness exist on background conoscopic figures. As object of the study
used the crystals LiNbO3, LiNbO3:Fe (0,3 %), LiNbO3:Ru (0,3%), LiNbO3:Fe+Cu (0,3+0,01 %), LiNbO3:Fe+Rh
(0,3+0,01 %), LiJO3, Ba1-xSrxNb2,O6, KDP. Thicknesses crystal lies within the range of from 0,5 mm before 23 mm.