Compact head-mounted display system having small input aperture and large output aperture

An optical device for transferring light waves, comprising:

• a first light-transmitting substrate having at least two parallel major surfaces and at least one edge;
• a light wave input aperture;
• a light wave output aperture positioned next to one of the major surfaces of the substrate;
• a light wave output pupil;
• a light wave input surface for coupling light waves, having a first field-of-view and a central light wave, into the substrate to effect total internal reflection from the major surfaces of the substrate, and
• at least one reflecting surface having an active area and being located between the two major surfaces of the light-transmitting substrate, for coupling light waves out of the substrate,
• wherein the input surface is configured to have a critical angle relative to light waves coupled inside the substrate and is oriented inside the substrate so that light waves coupled into the substrate through the input aperture substantially normal to the major surfaces of the substrate, are reflected at least a first and a second reflection by the input surface before being coupled into the substrate and are substantially reflected from one of the major surfaces between a first and a second reflectance from the input surface,
• the input surface is configured so that for the entire first field-of-view, the incident angles of the coupled light waves at the input surface are below the critical angle at the first reflection and above the critical angle at the second reflection, and
• wherein light waves coupled inside the substrate are reflected at least twice by the active side of the at least one reflecting surface before being coupled out from the substrate through the output aperture substantially normal to the major surfaces of the substrate, and light waves passing through the input aperture substantially normal to the major surfaces of the substrate, are reflected once by the input surface before being coupled into the substrate.