The polarization effect in the optical vortex interferometer

The optical vortices were intensively studied during last decade. In the literature there are papers presenting application of the optical vortices. The regular net of optical vortices generated by the three plane waves interference allows for the new kind of the interferometer - the Optical Vortex Interferometer (OVI). The precision of the OVI depends on the localization accuracy and the phase reconstruction. The localization methods give errors if we use beamsplitters with coatings changing the polarization state of the light. There are six beamsplitters used in this interferometer. In the setup we used non-polarizing coatings. We observed pleochroism effect, which occurs in these coatings. It is the cause of errors in the localization of optical vortices. In this paper we study the effect of pleochroism and we show the way to avoid errors in the localization of optical vortices in the OVI.