US Patent 8639072 Compact wearable display

There is provided a wearable display comprising a light source emitting light of a first wavelength; a first SBG device having a front side and a rear side; first and second transparent plates sandwiching said SBG device; independently switchable transparent electrode elements applied to the opposing surfaces of said transparent plates, a means for spatio-temporally modulating light from the light source to provide image light and a means for coupling the image light into the light guide formed by the two transparent plates and the SBG device. The SBG device comprises a multiplicity of selectively switchable grating regions. The SBG device diffracts image into the pupil of an eye.