US Patent 9335586 Polarization conversion systems with polarization gratings and related fabrication methods

A polarization conversion system includes a lens element, a polarization grating comprising a diffractive element having a spatially-varying local optical axis, and a retarder element. The polarization grating is arranged to receive light that is output from the lens element, and the retarder element arranged to receive polarized light of different polarization states that is output from the polarization grating and change the different polarization states to a same polarization state. Related devices and fabrication methods are also discussed.