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, characterized in that 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 so 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. (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, characterized in that 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 so 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.