Optical phase shift generated by liquid crystal planar cell
Variable spiral plate (VSP) for vortex beam generation

The variable spiral plate (VSP) is a passive liquid crystal optical element that is capable to modify the spatial distribution of the polarization of a homogenous polarized beam (as for example a simple Gaussian laser beam). The VSP is perfectly transparent optical element without losses (apart of the absorption losses of the material), scattering or diffracted light. The conversion from homogenous linear polarized beam to for example radial, azimuthal (or also lemon, spiral or star distribution) can simply be obtained by placing the VSP in the optical path of your laser beam. The different output polarization patterns can be obtained by simply changing the bias applied on the VSP.