Methods of fabrication of compound light-guide optical elements having embedded coupling-in reflectors

A method of fabricating a compound light-guide optical element (LOE):

• obtaining a first optical block comprising:
• at least a first pair of faces,
• a first region formed from a stack of LOEs, each of the LOEs having a pair of major parallel surfaces and a set of mutually parallel partially reflective internal surfaces located between the parallel surfaces and inclined obliquely to the parallel surfaces such that the first region comprises a first plurality of partially reflective internal surfaces, and
• a second region having a second plurality of mutually parallel partially reflective internal surfaces non-parallel to the first plurality of partially reflective internal surfaces;
• cutting the first optical block along a cutting plane that passes through one of the faces of the first pair of faces, thereby forming a first optical structure having an interfacing surface at the cutting plane;
• obtaining a second optical block having a second pair of faces and a plurality of mutually parallel reflective internal surfaces;
• bonding together the first optical structure and the second optical block such that one of the faces of the second pair of faces is joined to the interfacing surface and such that the plurality of reflective internal surfaces is non-parallel to both the first plurality of partially reflective internal surfaces and the second plurality of partially reflective internal surfaces, thereby forming a second optical structure;
• and
• slicing out at least one compound LOE from the second optical structure by cutting the second optical structure through at least two cutting planes substantially parallel to the major parallel surfaces of consecutive LOEs of the stack of LOEs.

A method of fabricating a compound light-guide optical element (LOE):

• obtaining a first optical block having a first pair of faces and a first plurality of mutually parallel partially reflective internal surfaces;
• obtaining a second optical block formed as a stack of LOEs and having a second pair of faces, each of the LOEs having a pair of major parallel surfaces and a second plurality of mutually parallel partially reflective internal surfaces oblique to the pair of major parallel surfaces;
• obtaining a third optical block having a third pair of faces and a third plurality of mutually parallel partially reflective internal surfaces;
• bonding together the first and third optical blocks and bonding together the second and third optical blocks to form a fourth optical block, wherein the bonding is such that:
• i) a first one of the faces of the first pair of faces is joined to a first one of the faces of the third pair of faces,
• ii) one of the faces of the second pair of faces is joined to a second one of the faces of the third pair of faces,
• iii) the third plurality of partially reflective internal surfaces is substantially parallel to the major parallel surfaces of the LOEs, and
• iv) the first, second, and third pluralities of partially reflective internal surfaces are mutually non-parallel;
• cutting the fourth optical block along a cutting plane that passes through a second one of the faces of the first pair of faces, thereby forming a first optical structure having an interfacing surface at the cutting plane;
• obtaining a fifth optical block having a fourth pair of faces and a fourth plurality of mutually parallel reflective internal surfaces;
• bonding together the first optical structure and the fifth optical block to form a second optical structure, wherein the bonding together the first optical structure and the fifth optical block is such that one of the faces of the fourth pair of faces is joined to the interfacing surface and such that the fourth plurality of reflective internal surfaces is non-parallel to the first, second, and third pluralities of partially reflective internal surfaces;
• and
• slicing out at least one compound LOE from the second optical structure by cutting the second optical structure through at least two cutting planes substantially parallel to the major parallel surfaces of consecutive LOEs in the stack of LOEs.

A method of fabricating a compound light-guide optical element (LOE):

• obtaining a first optical block having a first pair of faces and a first plurality of mutually parallel partially reflective internal surfaces;
• obtaining a second optical block formed as a stack of LOEs and having a second pair of faces, each of the LOEs having a pair of major parallel surfaces and a second plurality of mutually parallel partially reflective internal surfaces oblique to the pair of major parallel surfaces;
• obtaining a third optical block having a third pair of faces and a third plurality of mutually parallel partially reflective internal surfaces;
• bonding together the first and third optical blocks and bonding together the first and second optical blocks to form a fourth optical block, wherein the bonding is such that:
• i) a first one of the faces of the third pair of faces is joined to a first one of the faces of the first pair of faces,
• ii) one of the faces of the second pair of faces is joined to a second one of the faces of the first pair of faces,
• iii) the third plurality of partially reflective internal surfaces is substantially parallel to the major parallel surfaces of the LOEs, and
• iv) the first, second, and third pluralities of partially reflective internal surfaces are mutually non-parallel;
• cutting the fourth optical block along a cutting plane that passes through a second one of the faces of the third pair of faces, thereby forming a first optical structure having an interfacing surface at the cutting plane;
• obtaining a fifth optical block having a fourth pair of faces and a plurality of mutually parallel reflective internal surfaces;
• bonding together the first optical structure and the fifth optical block to form a second optical structure, wherein the bonding together the first optical structure and the fifth optical block is such that one of the faces of the fourth pair of faces is joined to the interfacing surface and such that the plurality of reflective internal surfaces is non-parallel to the first, second, and third pluralities of partially reflective internal surfaces, thereby forming a second optical structure;
• and
• slicing out at least one compound LOE from the second optical structure by cutting the second optical structure through at least two cutting planes substantially parallel to the major parallel surfaces of consecutive LOEs in the stack of LOEs.