In polarization-based optical systems, preserving a state-of-polarization (SOP) over a prescribed range of incidence angles and wavelengths may be necessary. Optical materials with local normal tilted with respect to an incident ray can introduce an undesirable polarization nonuniformity that can be substantially corrected using a compensator as disclosed herein. The compensator may include a uniaxial retarder and a z-partial polarizer (ZPP). The ZPP may include a uniaxial material with an absorption axis normal to the substrate.