| 摘要 |
A method and optical system for coupling light from an incoming light wave (WI) into a waveguiding substrate (S) arranges the light wave (WI) to interact with a diffractive in-coupling grating element or elements (IG) arranged on or embedded within the substrate (S) and arranged to couple the energy from the light wave (WI) into a waveguided light wave (WG). The polarization state of the light wave (WI) is converted after its first interaction (D 1 ) with the in-coupling grating element/elements (IG) and before a second interaction (D 2 ) with the grating element/elements (IG) takes place. The method minimizes any "reverse" diffractions, which would direct light back towards the front-end optics and therefore to increase the width W of the in-coupling grating/gratings (IG). Preferred embodiments include diffractive beam expanders for virtual displays. |
