Fig. 14
From: Waveguide-based augmented reality displays: perspectives and challenges
Working principle of 2D EPE for geometric waveguide combiner. Normalized \(k\)-vector diagram in the \({k}_{z}\)–\({k}_{x}\), \({k}_{x}\)–\({k}_{y}\), and \({k}_{z}\)–\({k}_{y}\) planes a after the initial refraction from air to the waveguide, b reflection at the in-coupling mirror, c reflection at the folding mirror and d reflection at the out-coupling mirror. Light paths before and after reflection on e in-coupling mirror, f folding mirror array, and g out-coupling mirror array in a geometric waveguide combiner with 2D EPE at normal incidence. Once the reflection happens, the coordinate will be rotate \({180}^{\circ}\). The dashed black lines represent the reflection symmetric axes (normal to the mirror’s surface). The dashed blue boxes correspond to the planes where the reflection takes place. Blue arrows represent light path in waveguide