Methods of fabrication of compound light-guide optical elements having embedded coupling-in reflectors
A stack has first and second faces and multiple LOEs that each has two parallel major surfaces and a first plurality of parallel internal facets oblique to the major surfaces. A first block has third and fourth faces and a second plurality of parallel internal facets. The first block and the stack are bonded such that the second face joins the third face and the first and second facets are non-parallel, forming a second block. The second block is cut at a plane passing through the first face, forming a first structure having an interfacing surface. A third block has fifth and sixth faces and a plurality of parallel internal reflectors. The third block and the first structure are bonded such that fifth face joins the interfacing surface and the internal reflectors are non-parallel to all the facets, forming a second structure. Compound LOEs are sliced-out from the second structure.
1 . An optical structure that is an intermediate work product of a compound light-guide optical element (LOE) fabrication process, the optical structure comprising:
a first region having a first pair of surfaces and a plurality of LOEs, each of the LOEs having a pair of major parallel surfaces and a first plurality of mutually parallel partially reflective internal surfaces oblique to the pair of major parallel surfaces;
a second region having a second pair of surfaces and a second plurality of mutually parallel partially reflective internal surfaces non-parallel to the first plurality of partially reflective internal surfaces, a first one of the surfaces of the first pair of surfaces and a first one of the surfaces of the second pair of surfaces being joined together, the second region further including an internal surface formed at a plane that passes through a second one of the surfaces of the second pair of surfaces; and
a third region having a third pair of surfaces and a plurality of mutually parallel reflective internal surfaces non-parallel to both the first plurality of partially reflective internal surfaces and the second plurality of partially reflective internal surfaces, a first one of the surfaces of the third pair of surfaces and the internal surface being joined together.
2 . The optical structure of claim 1 , wherein the second region has a pair of parallel external surfaces, and wherein the second plurality of partially reflective internal surfaces are perpendicular to the pair of parallel external surfaces of the second region.
3 . The optical structure of claim 1 , wherein the second region has a pair of parallel external surfaces, and wherein the second plurality of partially reflective internal surfaces are oblique to the pair of parallel external surfaces of the second region.
4 . The optical structure of claim 1 , wherein the second region has a third plurality of mutually parallel partially reflective internal surfaces non-parallel to the first and second pluralities of partially reflective internal surfaces.
5 . The optical structure of claim 4 , wherein the second region has a first sub-region that includes the second plurality of partially reflective internal surfaces and a second sub-region that includes the third plurality of partially reflective internal surfaces, wherein the first and second sub-regions of the second region are non-overlapping regions.
6 . The optical structure of claim 4 , wherein the third plurality of partially reflective internal surfaces are parallel to the major parallel surfaces of the plurality of LOEs.
7 . The optical structure of claim 4 , wherein each respective one of the third partially reflective internal surfaces is located in a plane that is approximately halfway between the pair of major parallel surfaces of a respective one of the LOEs of the plurality of LOEs.
8 . The optical structure of claim 4 , wherein the third plurality of partially reflective internal surfaces is located between the first and second pluralities of partially reflective internal surfaces.
9 . The optical structure of claim 4 , wherein the second plurality of partially reflective internal surfaces is located between the first and third pluralities of partially reflective internal surfaces.
10 . The optical structure of claim 1 , wherein the second region is formed by: i) bonding together first and second optical blocks that each have a pair of faces such that one of the faces of the pair of faces of the first optical block is joined to one of the faces of the pair of faces of the second optical block, and ii) cutting the first optical block along the plane to form the internal surface.
11 . The optical structure of claim 10 , wherein the first optical block includes the second plurality of partially reflective internal surfaces, and wherein the second optical block includes a third plurality of mutually parallel partially reflective internal surfaces non-parallel to the first plurality of partially reflective internal surfaces and non-parallel to the second plurality of partially reflective internal surfaces.
12 . The optical structure of claim 1 , wherein the third region includes at least one optically inert sub-region.
13 . The optical structure of claim 1 , wherein the internal surface is oblique to the second one of the surfaces of the second pair of surfaces.
14 . The optical structure of claim 1 , wherein the major parallel surfaces of the plurality of LOEs define a plurality of planes along which the optical structure is cut to extract one or more compound LOE.
15 . The optical structure of claim 14 , wherein each compound LOE of the extracted one or more compound LOE includes:
i) a pair of mutually parallel major external surfaces,
ii) a first set of mutually parallel partially reflective internal surfaces obliquely inclined to the pair of mutually parallel major external surfaces, the first set of mutually parallel partially reflective internal surfaces being from the first plurality of mutually parallel partially reflective internal surfaces,
iii) a second set of mutually parallel partially reflective internal surfaces oriented non-parallel to the first set of mutually parallel partially reflective internal surfaces, the second set of mutually parallel partially reflective internal surfaces being from the second plurality of mutually parallel partially reflective internal surfaces, and
iv) a reflective surface oriented non-parallel to both the first set of mutually parallel partially reflective internal surfaces and the second set of mutually parallel partially reflective internal surfaces, the reflective surface being one of the plurality of mutually parallel reflective internal surfaces.