Patent ID: 8810914

Claim:
An optical system, comprising: an optical device for collimating light waves including an arrangement of optical elements carried by a light-transmitting body, the device having a light waves exit surface; a transparent prism having at least two non-parallel external surfaces; a light-transmitting substrate having at least two major surfaces parallel to each other, edges and an input aperture; an optical element for coupling the collimated light waves into the substrate by internal reflection, and at least one partially reflecting surface located in the substrate for coupling light waves out of the substrate, said partially reflecting surface being non-parallel to the major surfaces of the substrate, wherein the input aperture of the light-transmitting substrate is positioned adjacent to one of the two external surfaces of the prism, and the other of the two external surfaces is positioned adjacent to the exit surface of the collimating optical device, characterized in that the light-waves trapped in the substrate, intersect the input aperture of the light-transmitting substrate at an oblique angle with respect to the major surfaces of the substrate, said oblique angle being greater than a critical angle for effecting the light waves internal reflection inside the substrate.