Polarized beam steering using multiply-cascaded rotating polarization gratings.

A polarized laser beam steering system using multiply cascaded rotating polarization gratings (PGs) is presented. The rotating PGs steer incident circularly polarized beams with high optical throughput because the theoretical limitation of the PG diffraction efficiency is 100%. The system also offers more rapid rotation when compared with wedge prism pairs because of the weight of the PGs. The beam steering performance was analyzed theoretically for schemes using two and four rotating PGs. The system's feasibility was demonstrated experimentally by projecting Lissajous and raster patterns using PGs fabricated from photocrosslinkable polymer liquid crystal films via a photo-alignment technique. The steered beam's diffraction efficiency and ellipticity were maintained at 83∼89 % and 96∼99 % , respectively, during PG rotation. This beam steering system will be applicable to light detection and ranging, optical imaging, and laser displays.