Low-obliquity beam scanner with reflective polarizer

Abstract

A beam scanner of a projector-based near-eye display includes a prismatic element with a reflective polarizer and a quarter-wave waveplate (QWP). The beam-folding prismatic element receives a polarized light beam from a light source and couples the beam to a tiltable reflector, e.g. a 2D tiltable MEMS reflector, for angular scanning the beam. The light beam impinging onto the tiltable reflector is separated from the light beam reflected from the tiltable reflector by polarization. The polarization-based separation is achieved by causing the light beam to propagate through the QWP before and after impinging onto the tiltable reflector. Upon double propagation of the light beam through the QWP, the beam changes its polarization to an orthogonal polarization, which enables its separation from the impinging beam. The beam scanner may receive multiple light beams from multiple light sources. A projector and a near-eye display based on such beam scanners are also disclosed.