Waveguide and head-mounted display device

A head-mounted display device configured to be disposed in front of at least one eye of a user, wherein the head-mounted display device comprises a display unit and a waveguide, wherein:

• the display unit is configured to provide an image beam;
• and
• the waveguide is configured to transmit the image beam to the at least one eye of the user, and the waveguide comprises a plate, at least one coupling-in prism, and a plurality of microstructures, wherein:
• the plate has a first surface and a second surface, and the image beam enters the plate through the first surface;
• the at least one coupling-in prism is located on the second surface, wherein the coupling-in prism has a first inclined surface, and the image beam is reflected by the first inclined surface and then transmitted in the plate;
• and
• the plurality of microstructures are located on the second surface, wherein each of the plurality of microstructures has a second inclined surface, the image beam is reflected by the second inclined surface and then exits from the first surface of the plate, and a difference between a refractive index of the coupling-in prism and a refractive index of the plurality of microstructures is less than 0.05.