Measuring Stokes parameters by means of a polarization grating

Ordinary gratings act on the amplitude and (or) the phase of a wave front. Polarization gratings produce instead a periodic modulation of the state of polarization. A simple grating of the latter type is constituted by a line ar polarizer whose orientation varies periodically along a Line. It is show n that, for a generic polarization state of the incident field, such a grat ing gives rise to first-order diffracted beams with counterrotating circula r polarizations. It is also shown that such a grating can be used for measu ring the Stokes parameters of a light beam in an achromatic manner. Several extensions are briefly discussed. (C) 1999 Optical Society of America.