An interferometer includes an optical assembly for directing an input optical field, a space-variant polarization converter, and an analyzer. The optical assembly is configured and operable to produce first and second spatially separated optical fields of incident coherent radiation of substantially the same intensity and different polarizations and to define first and second spatially separated optical paths for propagation of said first and second optical fields thereby allowing interaction between the first optical field and an element affecting a phase thereof in said first optical path. The space-variant polarization converter is accommodated in said combined path and being configured and operable to simultaneously apply space-variant polarization conversion to two beams corresponding to combined first and second optical fields having different polarizations and produce radially and azimuthally polarized beams respectively. The analyzer is located downstream of said polarization converter.