Patent ID: 11906731
Assignee: DISPELIX OY
Field: Optics (Instruments)
Classification: CPC G | IPC G

Claim 0:
1. A waveguide display element comprising:
a waveguide body,
an in-coupling grating arranged to the waveguide body,
two first exit pupil expander gratings on different sides of the in-coupling grating corresponding to said separate directions,
two second exit pupil expander gratings at least partly on different sides of the out-coupling grating that are adapted to receive light from the two exit pupil expander gratings, respectively, and
a single out-coupling grating adapted to receive light from at least one of the second exit pupil expander gratings,
wherein:
the in-coupling grating is configured to couple incoming light into the waveguide body into two separate directions using opposite diffraction orders for splitting the field of view of the incoming light,
the grating is further configured such that said coupling takes place only at wavelengths below a threshold wavelength residing in the visible wavelength range,
the in-coupling grating has a period, which is short enough to prevent coupling of wavelengths above said threshold wavelength into the waveguide body, and
at least part of the light is adapted to travel from the first exit pupil expander gratings to the second exit pupil expander gratings via a region of the waveguide layer on which the out-coupling grating is located, and further back to the out-coupling grating.