Reducing stray light transmission in near eye display using resonant grating filter

An optical system for displaying virtual images and real images, comprising:

• a see-through substrate of optical material forming a waveguide having a display side and a non-display side opposite the display side;
• a first diffractive optical element (DOE) disposed on the substrate, the first DOE having an input surface and configured as an in-coupling grating to receive one or more optical beams comprising the virtual images as an input to the optical system;
• a second DOE disposed on the display side of the waveguide and configured for pupil expansion of the one or more optical beams along a first direction,
• a third DOE disposed on the display side of the waveguide, the third DOE having an output surface on the display side of the waveguide and configured for pupil expansion of the one or more optical beams along a second direction, and further configured as an out-coupling grating to couple, as an output from the output surface on the display side of the waveguide, one or more optical beams comprising the virtual images, wherein the second and third DOEs operate as an exit pupil expander to provide the output one or more optical beams with expanded pupil relative to the input;
• and
• a resonant grating filter comprising a doubly-periodic grating microstructure configured to block stray light incident on the non-display side of the waveguide from being scattered by one or more of the DOEs in the exit pupil expander, the stray light being within a predetermined range of wavelengths and angles of incidence and the stray light further being separate from light forming the real images,
• wherein the resonant grating filter is a layer disposed on the non-display side of the waveguide and is distinct from the first, second, and third DOEs.