Patent ID: 7724442

Claim:
An optical device, comprising: a light-transmitting substrate having at least two major surfaces parallel to each other and edges and at least one partially reflecting surface located in the substrate which is not parallel to a major surface of the substrate; a display light source emitting collimated light waves located in a given field of view; and at least one optical element for coupling light waves from the display light source into the substrate by total internal light wave reflection, the optical element having at least one plane surface disposed at an angle to a major surface of the substrate; wherein a single point on a boundary line between the edge of the plane surface and one of the major surfaces of the substrate is illuminated by two different light rays from one of the collimated light waves from the display light source that enter the substrate in two different locations and are trapped inside the substrate by total internal reflection, the trapped light wave covering the entire area of the substrate.