Optical System

Abstract

An optical system employs a waveguide including a first set of partially-reflecting surfaces (“facets”) for progressively redirecting image illumination propagating from a coupling-in region towards a second region, and a second set of facets in the second region for progressively coupling-out the redirected image illumination towards the eye of a viewer. The first set of facets includes at least a first facet close to the coupling-in region, a third facet fare from the coupling-in region, and a second facet located on a medial plane between the first and the third facets. The second facet is located in a subregion of the medial plane such that image illumination propagating from the coupling-in region to the third facet passes through the medial plane without passing through the second facet.

What is claimed is: 
     
         1 . An optical system for directing image illumination injected at a coupling-in region to an eye-motion box for viewing by an eye of a user, the optical system comprising a light-guide optical element (LOE) formed from transparent material, said LOE comprising:
 (a) a first region containing a first set of planar, mutually-parallel, partially-reflecting surfaces having a first orientation;   (b) a second region containing a second set of planar, mutually-parallel, partially-reflecting surfaces having a second orientation non-parallel to said first orientation;   (c) a set of mutually-parallel major external surfaces, said major external surfaces extending across said first and second regions such that both said first set of partially-reflecting surfaces and said second set of partially-reflecting surfaces are located between said major external surfaces,   wherein said second set of partially-reflecting surfaces are at an oblique angle to said major external surfaces so that a part of image illumination propagating within said LOE by internal reflection at said major external surfaces from said first region into said second region is coupled out of said LOE towards the eye-motion box, and wherein said first set of partially-reflecting surfaces are oriented so that a part of image illumination propagating within said LOE by internal reflection at said major external surfaces from said coupling-in region is deflected towards said second region,   wherein said first set of partially-reflecting surfaces comprises a first partially-reflecting surface proximal to the coupling-in region so as to contribute to a first part of a field of view of the user as viewed at the eye-motion box, a third partially-reflecting surface distal to the coupling-in region so as to contribute to a third part of a field of view of the user as viewed at the eye-motion box, and a second partially-reflecting surface lying in a medial plane between said first and said third partially-reflecting surfaces so as to contribute to a second part of a field of view of the user as viewed at the eye-motion box, wherein said second partially-reflecting surface is deployed in a subregion of said medial plane such that image illumination propagating from said coupling-in region to said third partially-reflecting surface and contributing to the third part of the field of view of the user as viewed at the eye-motion box passes through said medial plane without passing through said second partially-reflecting surface.   
     
     
         2 . The optical system of  claim 1 , wherein said coupling-in region comprises a coupling-in prism having a first planar surface that is a continuation of one of said major external surfaces in said first region, said coupling-in prism having a thickness dimension measured perpendicular to said major external surfaces that is greater than a thickness of said LOE. 
     
     
         3 . The optical system of  claim 2 , wherein said coupling-in prism presents a coupling-in surface and a transition line between said coupling-in prism as said LOE, said coupling-in surface defining an optical aperture of said coupling-in prism in a dimension parallel to said major external surfaces and said transition line defining an optical aperture of said coupling-in prism in a dimension perpendicular to said major external surfaces. 
     
     
         4 . The optical system of  claim 2 , wherein said first set of partially-reflecting surfaces further comprises at least one partially-reflecting surface located within a volume of said coupling-in prism. 
     
     
         5 . An optical system for directing image illumination injected at a coupling-in region to an eye-motion box for viewing by an eye of a user, the optical system comprising a light-guide optical element (LOE) formed from transparent material, said LOE comprising:
 (a) a first region containing a first set of planar, mutually-parallel, partially-reflecting surfaces having a first orientation;   (b) a second region containing a second set of planar, mutually-parallel, partially-reflecting surfaces having a second orientation non-parallel to said first orientation;   (c) a set of mutually-parallel major external surfaces, said major external surfaces extending across said first and second regions such that both said first set of partially-reflecting surfaces and said second set of partially-reflecting surfaces are located between said major external surfaces,   wherein said second set of partially-reflecting surfaces are at an oblique angle to said major external surfaces so that a part of image illumination propagating within said LOE by internal reflection at said major external surfaces from said first region into said second region is coupled out of said LOE towards the eye-motion box, and wherein said first set of partially-reflecting surfaces are oriented so that a part of image illumination propagating within said LOE by internal reflection at said major external surfaces from said coupling-in region is deflected towards said second region,   wherein said coupling-in region comprises a coupling-in prism having a first planar surface that is a continuation of one of said major external surfaces in said first region, said coupling-in prism having a thickness dimension measured perpendicular to said major external surfaces that is greater than a thickness of said LOE,   and wherein said coupling-in prism presents a coupling-in surface and a transition line between said coupling-in prism as said LOE, said coupling-in surface defining an optical aperture of said coupling-in prism in a dimension parallel to said major external surfaces and said transition line defining an optical aperture of said coupling-in prism in a dimension perpendicular to said major external surfaces.   
     
     
         6 . The optical system of  claim 5 , wherein said first set of partially-reflecting surfaces further comprises at least one partially-reflecting surface located within a volume of said coupling-in prism. 
     
     
         7 . An optical system for directing image illumination injected at a coupling-in region to an eye-motion box for viewing by an eye of a user, the optical system comprising a light-guide optical element (LOE) formed from transparent material, said LOE comprising:
 (a) a first region containing a first set of planar, mutually-parallel, partially-reflecting surfaces having a first orientation;   (b) a second region containing a second set of planar, mutually-parallel, partially-reflecting surfaces having a second orientation non-parallel to said first orientation;   (c) a set of mutually-parallel major external surfaces, said major external surfaces extending across said first and second regions such that both said first set of partially-reflecting surfaces and said second set of partially-reflecting surfaces are located between said major external surfaces,   wherein said second set of partially-reflecting surfaces are at an oblique angle to said major external surfaces so that a part of image illumination propagating within said LOE by internal reflection at said major external surfaces from said first region into said second region is coupled out of said LOE towards the eye-motion box, and wherein said first set of partially-reflecting surfaces are oriented so that a part of image illumination propagating within said LOE by internal reflection at said major external surfaces from said coupling-in region is deflected towards said second region,   wherein said coupling-in region comprises a coupling-in prism having a first planar surface that is a continuation of one of said major external surfaces in said first region, said coupling-in prism having a thickness dimension measured perpendicular to said major external surfaces that is greater than a thickness of said LOE,   and wherein said first set of partially-reflecting surfaces further comprises at least one partially-reflecting surface located within a volume of said coupling-in prism.   
     
     
         8 . The optical system of  claim 7 , wherein said coupling-in prism presents a coupling-in surface and a transition line between said coupling-in prism as said LOE, said coupling-in surface defining an optical aperture of said coupling-in prism in a dimension parallel to said major external surfaces and said transition line defining an optical aperture of said coupling-in prism in a dimension perpendicular to said major external surfaces. 
     
     
         9 . The optical system of  claim 2 , wherein said coupling-in prism is bonded to said LOE at an edge surface of said LOE. 
     
     
         10 . The optical system of  claim 2 , wherein said coupling-in prism is bonded to one of said major external surfaces of said LOE. 
     
     
         11 . The optical system of  claim 3 , wherein said coupling-in prism is bonded to said LOE at an edge surface of said LOE. 
     
     
         12 . The optical system of  claim 3 , wherein said coupling-in prism is bonded to one of said major external surfaces of said LOE. 
     
     
         13 . The optical system of  claim 4 , wherein said coupling-in prism is bonded to said LOE at an edge surface of said LOE. 
     
     
         14 . The optical system of  claim 4 , wherein said coupling-in prism is bonded to one of said major external surfaces of said LOE 
     
     
         15 . The optical system of  claim 5 , wherein said coupling-in prism is bonded to said LOE at an edge surface of said LOE. 
     
     
         16 . The optical system of  claim 5 , wherein said coupling-in prism is bonded to one of said major external surfaces of said LOE. 
     
     
         17 . The optical system of  claim 6 , wherein said coupling-in prism is bonded to said LOE at an edge surface of said LOE. 
     
     
         18 . The optical system of  claim 6 , wherein said coupling-in prism is bonded to one of said major external surfaces of said LOE. 
     
     
         19 . The optical system of  claim 7 , wherein said coupling-in prism is bonded to said LOE at an edge surface of said LOE. 
     
     
         20 . The optical system of  claim 7 , wherein said coupling-in prism is bonded to one of said major external surfaces of said LOE.