Thermo-optically driven two-dimensional addressable retarder-plate

We demonstrate a polarization Michelson interferometer with one mirror replaced by a controllable mirror. The phase of the reflected beam and thereby the polarization state can be selectively modified in two dimensions. The required phase shift of the controllable mirror is induced by heating a thin layer of an aqueous Rhodamine B dye solution. Upon heating, the thermal dispersion of water of -1.5 x 10(-4) K-1 leads to a reduction of the refractive index and thereby a reduction of the optical path length. Heating is performed by illuminating the dye layer with the pattern from a video projector.