Waveguide Display Having Gratings with Continuous Phase Shifting

Abstract

A display may include a waveguide that directs image light to an eye box. The waveguide may include an optical coupler that redirects and replicates the light. The coupler may include a surface relief grating (SRG). The SRG may have a pitch that varies continuously along an axis orthogonal its ridges. The pitch may vary sinusoidally, linearly, parabolically, or according to other continuous and differentiable functions of position along the axis. The SRG may diffract the light. Upon diffracting the light, the SRG may impart a phase to the light. The phase may vary continuously as a function of position along a first axis and may, if desired, vary continuously as a function of position along a second axis orthogonal to the first axis. The SRG may prevent formation of coherent light paths after replication, thereby maximizing the efficiency of the system.

Dependencies are inferred from the claim text.