We present the results of birefringent media properties measurement using two different interferometers with polarizing
elements. These setups allow to generate regular and stable lattice of optical vortices (OVs) and to record the lattice
deformations caused by introduced birefringent plate. The first setup is a polariscope arrangement with two Wollaston
compensators placed between crossed polarizers. The shape of lattice basic cell is determined by the Wollaston's
shearing angle and examined birefringent medium causes only the shift of the whole OVs lattice. The calculated
displacement vector allows determining at least two parameters of measured medium simultaneously. This setup was
used also to measure the absolute value of the phase shift introduced by examined birefringent sample by using two light
sources with slightly different wavelength. We manage to determine the phase retardance order by tracking the center of
two interferograms made with and without sample. The second setup is based on modified Mach-Zehnder interferometer
in which the Wollaston compensator is inserted into the one of interferometer's arm. The measured birefringent medium
placed in another interferometer's arm causes the mutual displacement of two OVs sublattices with different topological
signs. Calculated displacements vectors between those two sublattices allows to determine birefringent sample
parameters.
In this paper the two-wavelength procedure for determining of the birefringence medium phase retardance order using
the optical vortex birefringence compensator (OVBC) is presented. The OVBC generates regular optical vortex lattice
which moves if the measured birefringent medium is placed into the compensator setup. Due to the vortex lattice
regularity, tracing the lattice shift after the measured medium is inserted, there is no possibility to determine the absolute
phase retardance in the monochromatic light. This is an analogy to the well known problem in the classical fringe
interferometry. Having recorded interferograms for two waves with slightly different wavelengths, one can identify the
centers of the two pairs of interferogram images (with and without the examined medium in the setup) and hence in that
way the absolute shift of the vortex lattice. In the paper the theoretical considerations, numerical simulations, as well as
the analysis of the interferograms taken from the experiment are presented.
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