Optical waveguide assembly and head-mounted display device

A head-mounted display device comprising:

• a frame defining an installation position;
• a light engine embedded within the frame and configured for emitting image light;
• and
• an optical waveguide assembly fixed to the installation position and comprising:
• a waveguide comprising a first surface and a second surface opposite to the first surface;
• a coupling-in grating on a light path of the image light;
• a coupling-out grating spaced apart from the coupling-in grating, wherein the coupling-in grating and the coupling-out grating are on a same surface of the waveguide or on the first surface and the second surface of the waveguide, respectively, the coupling-in grating is configured to couple the image light into the waveguide;
• the waveguide is configured to guide the image light toward the coupling-out grating, and the coupling-out grating is configured to couple the image light out of the waveguide;
• and
• a first lens fixed to a side of the waveguide emitting the image light and configured to refract the image light coupled out of the coupling grating, wherein an orthographic projection of the first lens on the waveguide covers an entirety of the coupling-out grating.