Transmitting the phase plate, the polarization beam splitter and a projection display device

A transmissive phase plate with a function of correcting direction of polarization of light rays in an incident divergent or convergent light flux in addition to functions as a wave plate. Conditions of polarization of incident light rays are corrected by a polarization-correcting optical multi-layer coating which is formed by alternately depositing a high refractivity layer and a low refractivity layer on curved substrative surface of a predetermined radius of curvature. The transmissive phase plate can be applied to correct conditions of polarization of incident light rays of a polarized beam splitter for the purpose of improving contrast ratio of a projection display.