Collimating optical device and system

A light-guide, compact imaging optical system, comprising:

• an optical device, composed of a light-wave transmitting material, for collimating light waves, the device having at least one light-wave entrance surface, at least one light-wave exit surface and a plurality of external surfaces;
• at least one light-wave reflecting surface carried by the optical device at one of the external surfaces;
• two or more retardation plates, each carried by the optical device on at least a portion of at least one of the external surfaces;
• at least one light-wave polarizing beamsplitter disposed at an angle to at least one of the light-wave entrance or exit surfaces;
• at least one light-wave collimating component covering at least a portion of at least one of the retardation plates;
• a light-transmitting substrate having at least two major surfaces parallel to each other, edges and a light-wave input aperture positioned adjacent to the exit surface of the optical device, the substrate containing at least one partially reflecting surface non-parallel to the major surfaces of the substrate;
• and
• an optical element for coupling light waves from the optical device into the substrate by internal reflection.