A light-guide optical element comprising: (a) a transparent substrate configured to receive polarized light and having at least two parallel major external surfaces for guiding light within the substrate by internal reflection at said external surfaces; and (b) a plurality of mutually parallel internal surfaces deployed within said substrate non-parallel to said major external surfaces, at least part of each of said internal surfaces comprising a structural polarizer having a primary polarization transmission axis, said structural polarizer being substantially transparent to light polarized parallel to said primary polarization transmission axis and being at least partially reflective to light polarized perpendicular to said primary polarization transmission axis, wherein said primary polarization transmission axis is rotated by an acute angle for each successive internal surface relative to a preceding one of said internal surfaces characterized in that said primary polarization transmission axis of said structural polarizer is rotated in a first direction between a first of said internal surfaces and a subsequent one of said internal surfaces , and is rotated in a second direction, opposite to said first direction, between said subsequent one of said internal surfaces and a further subsequent one of said internal surfaces . wherein said structural polarizer is substantially fully reflective to light polarized perpendicular to said primary polarization transmission axis, wherein said primary polarization transmission axis of said structural polarizer is rotated through a first angle between a first of said internal surfaces and a subsequent one of said internal surfaces , and is rotated through a second angle, greater than said first angle, between said subsequent one of said internal surfaces and a further subsequent one of said internal surfaces . (a) a transparent substrate configured to receive polarized light and having at least two parallel major external surfaces for guiding light within the substrate by internal reflection at said external surfaces; and (b) a plurality of mutually parallel internal surfaces deployed within said substrate non-parallel to said major external surfaces, at least part of each of said internal surfaces comprising a structural polarizer having a primary polarization transmission axis, said structural polarizer being substantially transparent to light polarized parallel to said primary polarization transmission axis and being at least partially reflective to light polarized perpendicular to said primary polarization transmission axis, wherein said primary polarization transmission axis is rotated by an acute angle for each successive internal surface relative to a preceding one of said internal surfaces characterized in that said primary polarization transmission axis of said structural polarizer is rotated in a first direction between a first of said internal surfaces and a subsequent one of said internal surfaces , and is rotated in a second direction, opposite to said first direction, between said subsequent one of said internal surfaces and a further subsequent one of said internal surfaces . wherein said structural polarizer is substantially fully reflective to light polarized perpendicular to said primary polarization transmission axis, wherein said primary polarization transmission axis of said structural polarizer is rotated through a first angle between a first of said internal surfaces and a subsequent one of said internal surfaces , and is rotated through a second angle, greater than said first angle, between said subsequent one of said internal surfaces and a further subsequent one of said internal surfaces . <EOS>