Method for manufacturing composite light guide optical element with embedded coupled reflector

Abstract

The stack has a first face and a second face and a plurality of LOEs, each LOE having two parallel major surfaces and a first plurality of parallel internal facets inclined relative to the major surfaces. The first block has a third face and a fourth face and a second plurality of parallel internal facets. The first block and the stack are joined such that the second face joins the third face and the first facet and the second facet are not parallel, thereby forming a second block. The second block is cut with a plane passing through the first face to form a first structure having abutting surfaces. The third block has a fifth face and a sixth face and a plurality of parallel internal reflectors. The third block and the first structure are joined such that the fifth face joins the abutting surfaces and the internal reflectors are not parallel to all facets, thereby forming a second structure. A composite LOE is cut from the second structure.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 235,837, filed on August 23, 2021, the entire disclosure of which is incorporated herein by reference. Technical Field

[0003] The present invention relates to light-guide optical elements (LOEs), and in particular to a method for manufacturing a composite LOE with embedded coupled reflectors for two-dimensional aperture expansion. Background Art

[0004] Composite LOEs or "two-dimensional expansion waveguides" have been described in various publications by Lumus Ltd (Israel). In general, these composite LOEs employ two regions, each of which is a parallel-facing block of transparent material (i.e., light-transmissive material) for promoting propagation of light corresponding to a collimated image by internal reflection at a major surface, and each of which includes a set of mutually parallel, internal, partially reflective surfaces (or "facets") that redirect the collimated image light while achieving expansion of the optical aperture. By combining two such elements with different facet orientations, a two-dimensional expansion of the optical aperture can be achieved within a single composite element, thereby expanding the input image from an image projector and outputting the expanded image over a large area toward the eye of an observer. Summary of the invention

[0005] Embodiments of the present invention provide methods of making composite LOEs.

[0006] According to the teachings of an embodiment of the present invention, a method for manufacturing a composite light-guiding optical element (LOE) is provided. The method includes: obtaining a stack having a first opposite face and a plurality of LOEs, each of the LOEs having a pair of main parallel surfaces and a first plurality of mutually parallel partially reflective inner surfaces inclined relative to the pair of main parallel surfaces; obtaining a first optical block having a second opposite face and a second plurality of mutually parallel partially reflective inner surfaces; bonding the first optical block and the stack together so that one of the faces of the first opposite face is coupled to one of the faces of the second opposite face, and so that the first plurality of partially reflective inner surfaces are not parallel to the second plurality of partially reflective inner surfaces, thereby forming a second optical block; cutting along a cutting plane passing through another face of the second opposite face a second optical block, thereby forming a first optical structure having a butt joint surface at a cutting plane; obtaining a third optical block having a third opposite surface and a plurality of mutually parallel reflective inner surfaces; bonding the third optical block and the first optical structure together so that one of the faces of the third opposite surface is coupled to the butt joint surface and the plurality of reflective inner surfaces are not parallel to both the first plurality of partially reflective inner surfaces and the second plurality of partially reflective inner surfaces, thereby forming a second optical structure; and cutting at least one composite LOE from the second optical structure by cutting the second optical structure via at least two cutting planes that are substantially parallel to the main parallel surfaces of the continuous LOE.

[0007] Optionally, the method further comprises: for each cut composite LOE, polishing an outer surface of the cut composite LOE formed by cutting the optical structure along two consecutive ones of the cutting planes.

[0008] Optionally, the first optical block has a pair of parallel faces, and the second plurality of partially reflective inner surfaces are perpendicular to the pair of parallel faces of the first optical block.

[0009] Optionally, the first optical block has a pair of parallel faces, and the second plurality of partially reflective inner surfaces are inclined relative to the pair of parallel faces of the first optical block.

[0010] Optionally, the first optical block has a third plurality of mutually parallel partially reflective inner surfaces that are non-parallel to the first plurality of partially reflective inner surfaces and the second plurality of partially reflective inner surfaces.

[0011] Optionally, the first optical block has a first region and a second region, the first region includes a second plurality of partially reflective inner surfaces, the second region includes a third plurality of partially reflective inner surfaces, and the first region and the second region of the first optical block are non-overlapping regions.

[0012] Optionally, the third plurality of partially reflective interior surfaces are parallel to the major parallel surfaces of the LOE.

[0013] Optionally, each individual one of the third partially reflective interior surfaces lies in a plane approximately midway between a pair of major parallel surfaces of a corresponding one of the LOEs.

[0014] Optionally, the third plurality of partially reflective interior surfaces is located between the first plurality of partially reflective interior surfaces and the second plurality of partially reflective interior surfaces.

[0015] Optionally, the second plurality of partially reflective interior surfaces is located between the first plurality of partially reflective interior surfaces and the third plurality of partially reflective interior surfaces.

[0016] Optionally, the first optical block is formed by bonding together a first constituent optical block and a second constituent optical block each having a pair of opposite surfaces, such that one of the opposite surfaces of the first constituent optical block is coupled to one of the opposite surfaces of the second constituent optical block, the first constituent optical block includes a second plurality of partially reflective inner surfaces, and the second constituent optical block includes a third plurality of mutually parallel partially reflective inner surfaces that are non-parallel to the first plurality of partially reflective inner surfaces and non-parallel to the second plurality of partially reflective inner surfaces.

[0017] Optionally, the third optical block and the first optical structure are joined together such that substantially all of one of the third opposing faces is coupled to substantially all of the abutment surface.

[0018] Optionally, the third optical block and the first optical structure are bonded together such that one of the third opposing faces is coupled to a portion of the abutment surface.

[0019] Optionally, the third optical block has an additional pair of faces, and the method further includes: obtaining an inert block having a first pair of faces and a second pair of faces; and joining the inert block and the third optical block together so that one of the faces of the first pair of faces of the inert block is coupled to one of the faces of the additional pair of faces of the third optical block, thereby forming a composite block having a first face and a second face, the first face of the composite block being formed by one of the faces of the third pair of faces and one of the faces of the second pair of faces of the inert block, and the second face of the composite block being formed by another of the faces of the third pair of faces and one of the faces of the second pair of faces of the inert block.

[0020] Optionally, the method further comprises: obtaining a second inert block having a pair of faces; and joining the second inert block and the composite block together such that one of the pair of faces of the second inert block is coupled to the second face of the composite block.

[0021] Optionally, bonding the third optical block and the first optical structure together comprises bonding a composite block and the first optical structure together such that a first face of the composite block is coupled to the abutment surface.

[0022] Optionally, the method further includes: obtaining an inert block having a pair of faces; and bonding the inert block and a third optical block together such that one of the pair of faces of the second inert block is coupled to the other of the pair of faces of the third optical block.

[0023] Optionally, the stack is a joined stack of LOEs and a plurality of transparent spacer plates, the LOEs and transparent spacer plates alternating along a length of the stack perpendicular to the major parallel surfaces of the LOEs.

[0024] Optionally, at least two cutting planes are located in consecutive spacer plates with one of the LOEs therebetween.

[0025] According to an embodiment of the present teachings, a method of manufacturing a composite light guide optical element (LOE) is also provided. The method includes: obtaining a first optical block, the first optical block including: at least a first opposite face; a first region formed by a stack of LOEs, each of the LOEs having a pair of major parallel surfaces and a set of a plurality of mutually parallel partially reflective internal surfaces, the plurality of mutually parallel partially reflective internal surfaces being located between the parallel surfaces and inclined obliquely relative to the parallel surfaces, such that the first region includes a first plurality of partially reflective internal surfaces; and a second region having a second plurality of mutually parallel partially reflective internal surfaces that are non-parallel to the first plurality of partially reflective internal surfaces; cutting the first optical block along a cutting plane passing through one of the faces of the first opposite face, thereby forming a first optical structure having a butt joint surface at the cutting plane; obtaining a second optical block, the second optical block having a second opposite face and a plurality of mutually parallel reflective internal surfaces; bonding the first optical structure and the second optical block together, such that one of the faces of the second opposite face is coupled to the butt joint surface, and such that the plurality of reflective internal surfaces are 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 cutting at least one composite LOE from the second optical structure by cutting the second optical structure through at least two cutting planes that are substantially parallel to the major parallel surfaces of consecutive LOEs.

[0026] Optionally, the stack is a joined stack of LOEs and a plurality of transparent spacer plates, the LOEs and transparent spacer plates alternating along a length of the stack perpendicular to the major parallel surfaces of the LOEs.

[0027] Optionally, at least two cutting planes are located in consecutive spacer plates with one of the LOEs therebetween.

[0028] Optionally, the first optical block further comprises an additional pair of faces, one of the main parallel surfaces of the LOE at the top end of the stack forming part of one of the faces of the additional pair of faces, and one of the main parallel surfaces of the LOE at the bottom end of the stack forming part of the other face of the additional pair of faces.

[0029] Optionally, the second optical sub-block includes a first sub-block area and a second sub-block area, the second plurality of partially reflective internal surfaces are located in the first sub-block area, the third plurality of mutually parallel partially reflective internal surfaces are located in the second sub-block area, and the third plurality of partially reflective internal surfaces are not parallel to the first plurality of partially reflective internal surfaces and are not parallel to the second plurality of partially reflective internal surfaces.

[0030] Optionally, the third plurality of partially reflective interior surfaces is located between the first plurality of partially reflective interior surfaces and the second plurality of partially reflective interior surfaces.

[0031] Optionally, the second plurality of partially reflective interior surfaces is located between the first plurality of partially reflective interior surfaces and the third plurality of partially reflective interior surfaces.

[0032] According to an embodiment of the teachings of the present invention, there is also provided a method for manufacturing a composite light-guiding optical element (LOE). The method includes: obtaining a first optical block having a first opposite face and a first plurality of mutually parallel partially reflective inner surfaces; obtaining a second optical block formed as a stack of LOEs and having a second opposite face, each of the LOEs having a pair of main parallel surfaces and a second plurality of mutually parallel partially reflective inner surfaces inclined relative to the pair of main parallel surfaces; obtaining a third optical block having a third opposite face and a third plurality of mutually parallel partially reflective inner surfaces; bonding the first optical block and the third optical block together and bonding the second optical block and the third optical block together to form a fourth optical block, the bonding being such that: i) one of the faces of the first opposite face is coupled to one of the faces of the third opposite face, ii) one of the faces of the second opposite face is coupled to another of the faces of the third opposite face, iii) the third plurality of partially reflective inner surfaces are substantially parallel to the main parallel surfaces of the LOE, and iv) The first plurality of partially reflective internal surfaces, the second plurality of partially reflective internal surfaces, and the third plurality of partially reflective internal surfaces are not parallel to each other; cutting the fourth optical block along a cutting plane passing through another of the first opposing faces, thereby forming a first optical structure having a butt joint surface at the cutting plane; obtaining a fifth optical block having a fourth opposing face and a plurality of mutually parallel reflective internal surfaces; bonding the first optical structure and the fifth optical block together to form a second optical structure, bonding the first optical structure and the fifth optical block together so that one of the fourth opposing faces is coupled to the butt joint surface, and so that the plurality of reflective internal surfaces are not parallel to the first plurality of partially reflective internal surfaces, the second plurality of partially reflective internal surfaces, and the third plurality of partially reflective internal surfaces; and cutting at least one composite LOE from the second optical structure by cutting the second optical structure through at least two cutting planes that are substantially parallel to the main parallel surfaces of the continuous LOE.

[0033] Optionally, the stack is a joined stack of LOEs and a plurality of transparent spacer plates, the LOEs and transparent spacer plates alternating along a length of the stack perpendicular to the major parallel surfaces of the LOEs.

[0034] Optionally, at least two cutting planes are located in consecutive spacer plates with one of the LOEs therebetween.

[0035] According to an embodiment of the teachings of the present invention, there is also provided a method for manufacturing a composite light-guiding optical element (LOE). The method includes: obtaining a first optical block having a first opposite surface and a first plurality of mutually parallel partially reflective inner surfaces; obtaining a second optical block formed as a stack of LOEs and having a second opposite surface, each of the LOEs having a pair of main parallel surfaces and a second plurality of mutually parallel partially reflective inner surfaces inclined relative to the pair of main parallel surfaces; obtaining a third optical block having a third opposite surface and a third plurality of mutually parallel partially reflective inner surfaces; bonding the first optical block and the third optical block together and bonding the first optical block and the second optical block together to form a fourth optical block, the bonding being such that: i) one of the faces of the third opposite surface is coupled to one of the faces of the first opposite surface, ii) one of the faces of the second opposite surface is coupled to another of the faces of the first opposite surface, iii) the third plurality of partially reflective inner surfaces are substantially parallel to the main parallel surfaces of the LOE, and iv) the first plurality of partially reflective inner surfaces are substantially parallel to the main parallel surfaces of the LOE. The invention relates to a method for preparing an optical structure comprising: providing a first optical structure and a second optical block, wherein the first optical structure comprises ...

[0036] Optionally, the stack is a joined stack of LOEs and a plurality of transparent spacer plates, the LOEs and transparent spacer plates alternating along a length of the stack perpendicular to the major parallel surfaces of the LOEs.

[0037] Optionally, at least two cutting planes are located in consecutive spacer plates with one of the LOEs therebetween.

[0038] Unless otherwise defined herein, all technical terms and / or scientific terms used herein have the same meaning as those of ordinary skill in the art to which the present invention belongs, which are generally understood by those skilled in the art. Although methods and materials similar or equivalent to those described herein can be used for the practice or test of embodiments of the present invention, exemplary methods and / or materials are described below. In the event of a conflict, this patent specification (including definitions) will prevail. In addition, materials, methods and examples are only illustrative, and are not intended to be necessarily restrictive. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Some embodiments of the present invention are described herein by way of example only with reference to the accompanying drawings. With specific reference to the accompanying drawings in detail, it is emphasized that the details shown are by way of example and for the purpose of illustrative discussion of embodiments of the present invention. In this regard, the description in conjunction with the accompanying drawings makes it clear to those skilled in the art how to practice embodiments of the present invention.

[0040] Attention is now directed to the accompanying drawings, in which like reference numerals or characters indicate corresponding or identical parts. In the accompanying drawings:

[0041] Figures 1A to 1C are schematic side, front, and plan views, respectively, of a composite LOE having a first LOE region having a first set of partially reflective interior surfaces and a second LOE region having a second set of partially reflective interior surfaces that are non-parallel to the first set of partially reflective interior surfaces;

[0042] Figure 2A and Figure 2B They are respectively Figures 1A to 1C schematic side and front views of a composite LOE similar to but including a third region having one or more third partially reflective interior surfaces;

[0043] Figure 3A is a schematic side view of an optical block formed into a stack of joined LOEs that can be used to form a second LOE region of a composite LOE in accordance with an embodiment of the present invention;

[0044] Figure 3B yes Figure 3A A schematic side view of one of the stacked LOEs;

[0045] Figure 3C can be cut at predetermined intervals to produce Figure 3A Schematic side view of a stack of bonded coated plates of LOE;

[0046] Figure 3D is joined to form Figure 3AA schematic side view of the LOE arranged in formation before stacking;

[0047] Figure 4A and Figure 4B are schematic front and isometric views, respectively, of an optical block having a plurality of partially reflective surfaces that can be used to form a first LOE region of a composite LOE according to an embodiment of the present invention;

[0048] Figure 4C can be cut at predetermined intervals to produce Figure 4A and Figure 4B A schematic front view of a stack of bonded coated plates of an optical block;

[0049] Figure 5A and Figure 5B are schematic front and isometric views, respectively, of an optical block having a plurality of partially reflective surfaces that can be used to form a third LOE region of a composite LOE according to an embodiment of the present invention;

[0050] Figure 5C can be cut at predetermined intervals to produce Figure 5A and Figure 5B A schematic side view of a stack of bonded coated plates of an optical block;

[0051] FIG. 6A to FIG. 6C are aligned before being joined together according to an embodiment of the present invention. Figure 3A , Figure 4A , Figure 4B , Figure 5A and Figure 5B Schematic isometric, front and side views of an optical block;

[0052] FIG. 7A to FIG. 7C They are respectively FIG. 6A to FIG. 6C corresponding schematic isometric, front and side views showing optical blocks joined together to form a new optical block according to an embodiment of the present invention;

[0053] Fig. 8A and Figure 8B Schematic isometric view and front view of a cutting plane according to an embodiment of the present invention, respectively, along which FIG. 7A to FIG. 7C The optical blocks are cut to produce new optical structures;

[0054] Fig. 9A and Fig. 9B By cutting along the cutting plane Fig. 8A and Figure 8B Schematic isometric view and front view of an optical structure formed by an optical structure of

[0055] FIG. 10A to FIG. 10Care schematic isometric, side, and front views, respectively, of an optical block having multiple reflective internal surfaces that can be used to form in-coupling reflectors of a composite LOE according to an embodiment of the present invention;

[0056] Fig. 10D can be cut at predetermined intervals to produce FIG. 10A to FIG. 10C A schematic side view of a bonded stack of coated plates of an optical block;

[0057] Fig.11A and Fig. 11B According to the embodiments of the present invention, Fig. 9A and Fig. 9B The optical structure and FIG. 10A to FIG. 10C Schematic isometric and front views of optical blocks being aligned before being joined together;

[0058] Fig. 12A and Fig. 12B They are respectively Fig.11A and Fig. 11B corresponding schematic isometric and front views showing an optical structure and an optical block joined together to form a new optical structure according to an embodiment of the present invention;

[0059] Fig.13 According to an embodiment of the present invention Fig. 12A and Fig. 12B Schematic side view of an optical structure showing cutting planes with predetermined intervals along which the optical structure can be cut to extract one or more composite LOEs;

[0060] FIG. 14A to FIG. 14C According to the embodiments of the present invention, Fig.13 After cutting the optical structure with two consecutive cutting planes, Fig. 12A and Fig. 12B Schematic side view, front view and plan view of a composite LOE cut out of an optical structure;

[0061] Fig.15 According to an embodiment of the present invention, FIG. 14A to FIG. 14C The two main outer surfaces of the composite LOE are polished and FIG. 14A to FIG. 14C A schematic side view of the final composite LOE produced by the composite LOE of ;

[0062] Fig.16A and Fig. 16B According to the embodiments of the present invention, FIG. 10A to FIG. 10C schematic isometric and front views of a reduced size optical block similar to an optical block of the embodiment of the present invention, the reduced size optical block being aligned with the first and second inert blocks prior to being joined together with the first inert block;

[0063] Fig.17A and Fig. 17B They are respectively Fig.16A and Fig. 16B corresponding schematic isometric and front views showing a first inert block and an optical block joined together to form a composite block and aligned with a second inert block before the composite block and the second inert block are joined together, according to an embodiment of the present invention;

[0064] Fig.18A and Fig.18B They are respectively Fig.17A and Fig. 17B corresponding schematic isometric and front views showing a second inert block and a composite block joined together to form a second composite block according to an embodiment of the invention;

[0065] Fig.19A and Fig.19B They are respectively Fig. 12A and Fig. 12B Similar schematic isometric and front views, but showing the optical components joined together to form an optical structure according to an embodiment of the present invention. Fig.18A and Fig.18B Composite blocks and Fig. 9A and Fig. 9B The optical structure of

[0066] Fig. 20A is with Figure 3D a similar schematic side view, but showing the LOE arranged in an alternating arrangement with a plurality of transparent cover sheets prior to joining the LOE and transparent cover sheets together in accordance with an embodiment of the present invention;

[0067] Fig. 20B are optical blocks that are bonded together to form a first LOE region that can be used to form a composite LOE according to an embodiment of the present invention. Fig. 20A Schematic side view of alternating LOEs and transparent cover plates;

[0068] Fig.21 According to an embodiment of the present invention Fig.13 A schematic side view of an optical structure similar to that of Fig. 20B An optical block; and

[0069] Fig. 22 According to an embodiment of the present invention, after cutting the optical structure along two consecutive cutting planes, Fig.21 Schematic side view of the optical structure cut out of the composite LOE. DETAILED DESCRIPTION

[0070] Embodiments of the present invention provide methods of making composite LOEs.

[0071] The principles and operation of the method according to the present invention may be better understood with reference to the accompanying drawings of the specification. The accompanying drawings provide an xyz coordinate system, which is arbitrarily labeled but consistent between the drawings. The xyz coordinate system is used herein to better illustrate the disclosed embodiments by providing a common reference system between the drawings.

[0072] Before explaining at least one embodiment of the present invention in detail, it should be understood that the present invention is not necessarily limited in its application to the details of the construction and arrangement of the components and / or methods described in the following description and / or described in the drawings and / or examples. The present invention can have other embodiments or can be practiced or implemented in various ways.

[0073] Referring now to the accompanying drawings, Figures 1A to 1C Various views of a composite LOE 1 are shown. The composite LOE 1 comprises a first LOE 10 and a second LOE 20 bonded together at an interface 40. Typically, the two LOEs 10, 20 are manufactured separately and bonded together. In this document, the term "bonded" or "bonded" should be understood to mean attached or adhered with an optical cement or glue or any other suitable adhesive.

[0074] The first LOE 10 is formed of a light-transmissive material and includes: first pairs of faces 12a, 12b (which may or may not be parallel faces), second pairs of faces (major outer surfaces) 14a, 14b (which are a pair of parallel faces), third pairs of faces (major outer surfaces) 16a, 16b (which may or may not be parallel faces), and a plurality of mutually parallel partially reflective interior surfaces (also referred to as "facets") 18, the plurality of facets at least partially passing through the LOE 10 between the faces 16a, 16b. The LOE 10 is configured to direct light (image illumination) corresponding to a collimated image injected into the LOE 10 by an image projector (not shown) such that the light (at Figure 1B The propagating (trapped) light is captured in one dimension by internal reflection (preferably but not exclusively total internal reflection) at the parallel faces 14a, 14b of the LOE 10. The LOE 10 is also configured to gradually couple the propagating (trapped) light out of the LOE 10 via facets 18, which are tilted obliquely to the propagation direction of the light and each of which reflects a proportion of the intensity of the propagating light, thereby extending the image illumination in one dimension (in this case, approximately along the y-axis). In the figure, the light coupled out of the LOE 10 through the facets 18 is represented by light 60 ( Figure 1A and Figure 1B ), and the propagation of the collimated image light 50 by internal reflection at the face of the LOE 10 is represented by the left and right rays 52 ( Figure 1A)express.

[0075] Typically, facet 18 has a first orientation in composite LOE 1. In some embodiments, facet 18 is at an oblique angle relative to faces 14, 14b. In other embodiments, facet 18 is orthogonal to faces 14a, 14b. It should also be noted that in some embodiments, facet 18 may be at an oblique angle to one or both of faces 12a, 12b, while in other embodiments, facet 18 may be orthogonal to one or both of faces 12a, 12b. Figure 1A and Figure 1B In the non-limiting example embodiment shown, faces 12a, 12b are parallel and facets 18 are obliquely inclined to faces 12a, 12b.

[0076] The reflectivity of facets 18 may be provided via a coating on the interior surface prior to forming LOE 10. The reflectivity of each of facets 18 may be the same, or the reflectivity of facets 18 may differ from one another and may increase along the direction of light propagation (which is along the y-axis in the arbitrarily labeled xyz coordinate system in the drawings).

[0077] Light coupled out of LOE 10 is coupled into a second LOE 20. LOE 20 is also formed of a light transmissive material and includes first pairs of opposite faces 22a, 22b (which may or may not be parallel faces), second pairs of opposite faces (major outer surfaces) 24a, 24b (which are a pair of parallel faces), third pairs of opposite faces (major outer surfaces) 26a, 26b (which may or may not be parallel faces), and a plurality of mutually parallel partially reflective inner surfaces ("facets") 28 that are obliquely inclined relative to faces 24a, 24b. Faces 14a, 24a are substantially coincident (coplanar) to form a first single outer face of the composite LOE 1. Similarly, faces 14b, 24b are substantially coincident (coplanar) to form a second single outer face of the composite LOE 1. Faces 16a, 26a also preferably generally coincide (coplanar) to form a third single exterior face of composite LOE 1, and faces 16b, 26b also preferably generally coincide (coplanar) to form a fourth single exterior face of composite LOE 1. The remaining two exterior surfaces of composite LOE 1 are formed by faces 12a and 22b, respectively.

[0078] Facets 28 have a second orientation in composite LOE 1 that is non-parallel to the first orientation of facets 18. The reflectivity of facets 28 may be provided via a coating on the interior surface prior to forming LOE 20. The reflectivity of each of facets 28 may be the same, or the reflectivity of facets 28 may be different from one another and may increase along the direction of light propagation (which is along the x-axis in the arbitrarily labeled xyz coordinate system in the drawings).

[0079] Light from LOE 10 is coupled into LOE 20 through interface 40 (which coincides with facets 12b and 22a). LOE 20 is configured to guide light by internal reflection (preferably but not exclusively total internal reflection) at faces 24a, 24b, and to gradually couple the propagating light out of LOE 20 toward the eye of the observer via facets 28 (facets 28 each reflect a proportion of the intensity of the propagating light), thereby extending the image illumination in the second dimension (in this case, along the x-axis). Figure 1A In FIG. 1 , the propagation of image light through LOE 20 by internal reflection at faces 24a, 24b is represented by sets of light rays 62, 63. One of light rays 62, 63 represents the image, and the other of light rays 62, 63 represents the image conjugate corresponding to light 60 coupled into LOE 20 from LOE 10. Figure 1A Light coupled out of LOE 20 by facet 28 is represented by light ray 64 .

[0080] The image illumination to be coupled into the composite LOE 1 to be directed by the LOE 10 and LOE 20 is generated by an external image projector (not shown), which is typically implemented as a microprojector arrangement formed by a microdisplay device (e.g., an LCoS chip) generating the image illumination and a collimating optic for collimating the image illumination to produce collimated image illumination. The collimated image illumination is coupled into the LOE 10 by a coupling-in optical arrangement in the form of a highly reflective inner surface 42 in the coupling-in region of the LOE 10.

[0081] In order to fill the LOE 20 with collimated image illumination (whereby both the image and its conjugate propagate through the LOE by internal reflection) while maintaining a small input aperture (small projector), it is preferred to employ at least one additional partially reflective internal surface having a specific orientation relative to the facets 18, 28 and the faces of the composite LOE. Figure 2A and Figure 2B A composite LOE is shown with such an additional facet 38. The facet 38 may be disposed in a portion of the LOE 10, or as Figure 2A and Figure 2B Shown as part of a single light transmissive substrate 30 having three opposite faces 32a, 32b, 34a, 34b, 36a, 36b (where opposite faces 34a, 34b are a pair of parallel faces). Facet 38 is parallel to faces 14a, 14b, 24a, 24b, and therefore has an orientation that is non-parallel to the orientation of facets 18, 28. When only a single facet 38 is used, facet 38 is preferably located midway between faces 24a, 24b (and equivalently midway between faces 14a, 14b). If more than one facet 38 is used, facets 38 are preferably evenly spaced between faces 24a, 24b. In Figure 2A and Figure 2B In the illustrated embodiment, LOE 10 and substrate 30 are joined together at faces 12b, 32a, and substrate 30 and LOE 20 are joined together at faces 22a, 32b, such that facet 38 is located between groups of facets 18, 28. However, it is noted that other arrangements are possible, such as where facet 18 is located between facet 38 and groups of facets 28, depending on the design specifications of a particular application of the composite LOE.

[0082] In the illustrated embodiment, light 60 (outcoupled by facet 18) is partially reflected by facet 38. The reflected and transmitted portions of light 60 are coupled into LOE 20 and correspond to light ray 62 and light ray 63, respectively.

[0083] Composite LOEs (including those that may be related to Figures 1A to 2B For additional details of a composite LOE similar to the composite LOE shown in ), publications include, for example, U.S. Patent Application Publication No. 2021 / 0247608, PCT Publication WO 2021 / 240513, PCT Publication WO 2021 / 152602, PCT Publication WO 2021 / 001841, and U.S. Patent No. 10,551,544.

[0084] Embodiments of the present invention relate to methods of making composite LOEs. Composite LOEs made according to the methods of the present invention may be structurally different from Figures 1A to 2B The composite LOE shown in FIG. 1 is not a composite LOE, but has similar components, as will become apparent from the subsequent description. Figures 3A to 21 The manufacturing method steps are described in detail and generally include the following steps: obtaining an optical block 400 ( FIG. 7A to FIG. 7C ), the optical block having the set of required facets 18, 28 (and preferably also the set of facets 38) embedded in the region of the optical block 400 and appropriately oriented relative to each other so that the facets 18, 28 (and 38) are not parallel to each other; cutting a portion of the optical block 400 with a prescribed cutting plane ( Fig. 8A and Figure 8B ), the prescribed cutting plane is at a prescribed angle and passes through a specific face of the optical block 400 to form an optical structure 400', the optical structure 400' having a butt joint surface ( Fig. 9A and Fig. 9B ); obtaining an additional optical block 500 having a set of reflective inner surfaces 42 embedded therein ( FIG. 10A to FIG. 10D ); and bonding the optical block 500 to the optical structure 400' at the interface surface to form an intermediate optical structure 600 ( Fig. 12A and Fig. 12B ), the intermediate optical structure having the set of required facets 18, 28 (and preferably also the set of facets 38) embedded therein and the set of reflective inner surfaces 42 that are not parallel to the facets 18, 28, 38. The intermediate optical structure 600 is then cut along two or more cutting planes to cut out one or more composite LOEs ( Figures 13 to 14B ), wherein each composite LOE has facets 18 and 28 (and preferably also at least one facet 38) and an embedded reflective inner surface 42. Each of the cut composite LOEs may then be polished to obtain a final composite LOE having a desired thickness ( Fig.15 In certain embodiments, one or more blocks 800, 900 of inert material are bonded to the optical block 500 to form a composite block 590 ( FIG. 16A to FIG. 18B ), and then the composite block 590 is bonded to the optical structure 400' ( Fig.19A and Fig.19B ) to form the intermediate optical structure 600. As will be discussed, obtaining the optical block 400 may include obtaining various other optical blocks 100, 200, 300 ( FIG. 3A to FIG. 5C ) and bonding these optical blocks 100, 200, 300 together to form the optical block 400 to produce the optical block 400. Each of the optical blocks 100, 200, 300 has one of the necessary set of facets 18, 28, 38 embedded therein, and can be produced by set-bonded coated plates cut at appropriate angles and thicknesses.

[0085] It is noted that in the accompanying drawings, and in accordance with a set of non-limiting embodiments of the present invention, each of the individual blocks 100, 200, 300, 400, 500, 800, 900 is represented as a rectangular cube, i.e., a structure having three pairs of mutually perpendicular (orthogonal) parallel faces. However, the blocks are represented as rectangular cubes in this way only for clarity of presentation, and from an optical point of view or a manufacturing point of view, parallelism and perpendicularity between all faces of the individual blocks are not strict requirements. In many embodiments, only one pair of faces of a block need to be a pair of parallel faces, while the remaining faces may or may not be parallel. In other embodiments, no face of a block needs to be a pair of parallel faces.

[0086] The following paragraphs refer to FIG. 3A to FIG. 3D The structure and production of the optical block 200 are described. Figure 3A, shows an optical block 200 formed as a stack of LOEs 20 joined together. The optical block 200 has at least two pairs of opposite faces (major outer surfaces), namely a pair of preferably parallel faces 212a, 212b, and a pair of opposite faces 214a, 214b, which are a pair of parallel faces and can be orthogonal (perpendicular) to either or both of the faces 212a, 212b. The optical block 200 also includes a third pair of opposite faces, which may or may not be a pair of parallel faces and may also be perpendicular to one or more of the faces 212a, 212b, 214a, 214b. The third pair of opposite faces is not shown in FIG. Figure 3A shown in, but in the Figure 6B , Figure 7B , Figure 8B , Fig. 9B , Fig. 11B , Fig. 12B and Fig.19B As will become apparent, face 214a and face 214b may form a portion of an upper face and a lower face, respectively, of an optical structure 600 (FIGS. 11C and 11D) from which a composite LOE may be cut.

[0087] Figure 3A Each of the LOE 20 in the stack is as Figure 3B The LOE 20 is also generally similar to the above reference Figure 1A To the second LOE 20 discussed in FIG. 2C. Figure 3B As shown, and as mentioned above Figure 1A As discussed in relation to FIG. 2C , each LOE 20 is formed of a light-transmitting material, each LOE having parallel faces 24a, 24b and a set (or multiple) of internal facets 28 obliquely inclined to the faces 24a, 24b. Such a LOE can be used as a stand-alone LOE (together with appropriate coupling-in optics) when only one-dimensional aperture expansion is desired. This type of LOE is generally referred to as a "one-dimensional" LOE, and the structure and method of making such a one-dimensional LOE has been extensively described in various publications by Lumus Ltd. (Israel), including, for example, U.S. Patent No. 7,634,214, U.S. Patent No. 8,873,150, PCT Publication No. WO2016 / 103263, and PCT Publication No. WO 2020 / 212835.

[0088] Figure 3C One example method of manufacturing a plurality of LOEs 20 that may be used to produce an optical block 200 is shown. Figure 3CIn the embodiment of the present invention, a plurality of light-transmissive sheets are coated to form coated sheets 202 that are stacked and joined together, and then cut along equally spaced parallel cutting planes 206 (which are parallel to the xy plane in an arbitrarily labeled xyz coordinate system). Each of the sheets 202 has a pair of parallel faces (surfaces) 204a, 204b that are appropriately coated with a coating that provides reflectivity of the facets 28 (so that the facets 28 are partially reflective). The cutting planes 206 are inclined relative to the faces 204a, 204b and define the angle of inclination of the facets 28, and the resulting cuts along the cutting planes 206 define the faces 24a, 24b of the LOE 20. The cutting planes 206 are spaced apart at predetermined intervals. Preferably, the predetermined intervals are uniform intervals, so that the cutting planes 206 are uniformly spaced apart. The uniform intervals are preferably in the range of 1 mm to 2 mm, so that the thickness of each LOE 20 (measured between the faces 24a, 24b) is approximately 1 mm to 2 mm.

[0089] Before the LOEs 20 are joined together to form the optical block 200, the LOEs 20 are first aligned and arranged according to the arrangement 210 ( Figure 3D ). The LOEs 20 in the arrangement 210 are then joined together to form an optical block 200 as a joined stack of LOEs 20 ( Figure 3A ), so that the faces 24a and 24b of adjacent (continuous) LOEs 20 are joined together at the bonding area, and so that the grouped internal facets 28 of the LOE 20 constitute the plurality of facets 28 of the optical block 200. Figure 3A and Figure 3D As can be seen in FIG. 2 , the major surface 24 a of the LOE 20 at the top end of the stack 200 forms a top surface 214 a of the stack 200 , and the major surface 24 b of the LOE 20 at the bottom end of the stack 200 forms a bottom surface 214 b of the stack 200 .

[0090] The following paragraphs refer to FIG. 4A to FIG. 4C The structure and production of the optical block 100 are described. Figure 4A and Figure 4B , the optical block 100 is formed of a light-transmitting material and has an embedded set of facets 18. The optical block 100 includes three pairs of faces (major outer surfaces), namely a pair of faces 112a, 112b (which may or may not be parallel faces), a pair of preferably parallel faces 114a, 114b, and a pair of faces 116a, 116b (which may or may not be parallel faces). In some embodiments, the pairs of faces of the optical block 100 are orthogonal (perpendicular) to each other, which can simplify the manufacturing process.

[0091] The optical block 100 may be formed of a plurality of bonded transparent coated plates 102 (each plate is formed of a light-transmitting material and coated with a partially reflective coating) to form a facet 18 at a predetermined angle relative to the faces 114a, 114, that is, the facet 18 may be inclined obliquely relative to the faces 114a, 114b or may be orthogonal to the faces 114a, 114b. The facet 18 may also be inclined obliquely relative to the faces 112a, 112b at a predetermined angle. There are various known methods for forming the optical block 100. Figure 4C One such method is shown, wherein coated sheets 102 are stacked and joined together (e.g., similar to Figure 3C ), and then cut along a first pair of preferably parallel cutting planes 104 and along a second pair of preferably parallel cutting planes 106 that are preferably perpendicular to the planes 104 to extract the optical block 100. In embodiments where the facets 18 are tilted relative to one or both of the faces 112a, 112b, the angle of the cutting planes 104 relative to the face of the coated plate 102 determines the angle at which the facets 18 are tilted relative to the faces 112a, 112b. Additionally, the cutting along the cutting planes 104 defines the faces 112a, 112b of the optical block 100, and the cutting along the cutting planes 106 defines the faces 116a, 116b of the optical block 100.

[0092] In certain embodiments, for example Figure 4C In the illustrated embodiment, the cutting planes 104, 106 are perpendicular to the thickness dimension of the plate 102, such that the resulting facets 18 are perpendicular to the faces 114a, 114b of the optical block 100. In the arbitrarily labeled xyz coordinate system used in the drawings, when the cutting planes 104, 106 are perpendicular to the thickness dimension of the plate 102, the cutting plane 104 is parallel to the yz plane and the cutting plane 106 is parallel to the xz plane. The cutting plane 106 is perpendicular to the plane 104.

[0093] As described above, other embodiments are possible in which facets 18 are tilted obliquely relative to faces 114a, 114b, and therefore, cutting plane 106 may be tilted at an appropriate tilt angle relative to the xz plane to produce the appropriate facet angle relative to faces 114a, 114b.

[0094] The following paragraphs refer to FIG. 5A to FIG. 5C The structure and production of the optical block 300 are described. Figure 5A and Figure 5B, the optical block 300 is formed of a light-transmitting material and has an embedded set of facets 38. The optical block 300 includes three pairs of faces (major outer surfaces), namely a pair of faces 312a, 312b (which may or may not be parallel faces), a pair of preferably parallel faces 314a, 314b, and a pair of faces 316a, 316b (which may or may not be parallel faces). In certain non-limiting embodiments, the pairs of faces of the optical block 100 are orthogonal (perpendicular) to each other.

[0095] The optical block 300 may be formed from a plurality of bonded transparent coated plates 302, each plate formed of a light transmissive material and coated with a partially reflective coating, to form facets 38 parallel to the faces 314a, 314b and optionally perpendicular to one or both faces 312a, 312b. There are various known methods for forming the optical block 300. Figure 5C One such method is shown, in which coated sheets 302 are stacked and joined (e.g., similar to Figure 3C and Figure 4C ), and then cut along a pair of cutting planes 304 to extract the optical block 100. In some embodiments, for example Figure 5C In the illustrated embodiment, planes 304 are parallel planes (which are parallel to the yz plane in the arbitrarily labeled xyz coordinate system). However, as mentioned above, parallelism between planes 304 is not a strict requirement, and in some cases, it is advantageous to cut along non-parallel cutting planes, which can improve the compactness and overall form factor of the final composite LOE product. In some embodiments, planes 304 are perpendicular to the major outer surface (face) of plate 202. However, such perpendicularity is also not an optical requirement for producing the final composite LOE product, but rather a matter of practical convenience when manufacturing the composite LOE. The stacked and joined plates can also be cut along another pair of cutting planes 306 that pass through two of the plates and can be parallel to the major outer surface of plate 202 and perpendicular to planes 304. In the arbitrarily labeled xyz coordinate system used in the drawings, cutting planes 306 are parallel to the xy plane.

[0096] Continue to refer to Figures 1A to 5C , now refer to FIG. 6A to FIG. 6C , which shows that after being joined together to form an optical block 400 ( FIG. 7A to FIG. 7C ) before being joined. Prior to joining, it is important to properly align the optical blocks 100, 200, 300 so that the orientation of facet 18 is not parallel to the orientation of facet 28, and so that the orientation of facet 38 is not parallel to the orientation of facets 18, 28. In other words, align the blocks 100, 200, 300 so that facets 18, 28, 38 are not parallel to each other.

[0097] It is also preferred that the optical block 300 be aligned with the optical block 200 such that the facets 38 of the optical block 300 are in a plane parallel to the plane of the faces 214a, 214b of the optical block 200. In embodiments where each composite LOE will have only a single facet 38, it is preferred that the optical block 200 and the optical block 300 be aligned such that each respective facet 38 is located in a plane approximately midway between the major outer surfaces 24a, 24b of a respective one of the LOEs 20 forming the optical block 200. In embodiments where each composite LOE will have a plurality of facets 38, such as N facets 38, it is preferred that the optical block 200 and the optical block 300 be aligned such that for each set of N facets 38, the N facets 38 are evenly spaced between the major outer surfaces 24a, 24b of a respective one of the LOEs 20 forming the optical block 200. However, it is noted that block 300 can be positioned relative to block 200 without much scrutiny regarding the positioning of facets 38 relative to major exterior surfaces 24 a, 24 b, and that any mis-positioning of facets 38 relative to major exterior surfaces 24 a, 24 b in the cut composite LOE can be corrected (typically by polishing or grinding) in the final stages of manufacture if sufficient spare area is present in the cut composite LOE.

[0098] Reference FIG. 6A to FIG. 6C 1. Using the coordinate system shown, the alignment of optical blocks 100, 200, 300 (when each such optical block is constructed as a rectangular cube) can be understood as follows: each of faces 112a, 212a, 312a is in a plane parallel to the yz plane, each of faces 112b, 212b, 312b is in a plane parallel to the yz plane, each of faces 114a, 214a, 314a is in a plane parallel to the xy plane, each of faces 114b, 214b, 314b is in a plane parallel to the xy plane, each of faces 116a, 216a, 316a is in a plane parallel to the xz plane, and each of faces 116b, 216b, 316b is in a plane parallel to the xz plane. The alignment of optical blocks 100, 200, 300 also allows each of facets 38 to be in a plane parallel to the xy plane.

[0099] To reduce waste, the optical blocks 100, 200, 300 are preferably designed to have the same or very close to the same dimensions, i.e., length, width, and thickness. In the xyz coordinate system arbitrarily marked in the drawings, the length is measured along the y-axis (i.e., measured between the surfaces 116a, 116b, the surfaces 216a, 216b, and the surfaces 316a, 316b). In the xyz coordinate system arbitrarily marked in the drawings, the width is measured along the x-axis (i.e., measured between the surfaces 112a, 112b, the surfaces 212a, 212b, and the surfaces 312a, 312b). In the xyz coordinate system arbitrarily marked in the drawings, the thickness is measured along the z-axis (i.e., measured between the surfaces 114a, 114b, the surfaces 214a, 214b, and the surfaces 314a, 314b).

[0100] Employing optical blocks 100, 200, 300 having the same thickness (or very close to the same thickness) is critical to minimizing waste from the final cutting step to cut out the composite LOE. Thus, in a particularly preferred embodiment, the optical blocks 100, 200, 300 are aligned such that: faces 114a, 214a, 314a are coplanar (i.e., lie in a common plane), faces 114b, 214b, 314b are coplanar, faces 112a, 212a, 312a are coplanar, faces 112b, 212b, 312b are coplanar, faces 116a, 216a, 316a are coplanar, and faces 116b, 216b, 316b are coplanar.

[0101] Once properly aligned, such as FIG. 7A to FIG. 7C As shown, the optical blocks 100, 200, 300 are joined together to form an optical block 400 (which is a composite optical block including a plurality of sub-blocks), while maintaining the reference FIG. 6A to FIG. 6CIn the embodiment shown, the optical block 400 is a rectangular cube and has three regions, namely: one region with the optical block (stack) 200 carrying the bonded LOE 20 with the facet 28, another region with the optical block 300 carrying the facet 38, and another region with the optical block 100 carrying the facet 18. In the embodiment shown, the three regions do not overlap, and the three optical blocks 100, 200, 300 have the same thickness. In such an embodiment, faces 112a, 212b form a first pair of parallel faces 412a, 412b of the optical block 400, faces 414a (formed by coplanar faces 114a, 214a, 314a) and faces 414b (formed by coplanar faces 114b, 214b, 314b) form a second pair of parallel faces of the optical block 400, and faces 416a (formed by coplanar faces 116a, 216a, 316a) and faces 416b (formed by coplanar faces 116b, 216b, 316b) form a third pair of parallel faces of the optical block 400. It should be noted that in embodiments where the block 400 is not a rectangular cube, any pair of the three pairs of faces 412a, 412b, 414a, 414b, 416a, 416b need not necessarily be a pair of parallel faces.

[0102] As from Figure 3A , Figure 3D , Fig. 7A 7D , the major surface 24 a of the LOE 20 at the top end of the stack 200 forms a portion of the top surface 414 a of the optical block 400 , and the major surface 24 b of the LOE 20 at the bottom end of the stack 200 forms a portion of the bottom surface 414 b of the optical block 400 .

[0103] In some embodiments, optical blocks 100, 200, 300 may be joined together in stages. For example, optical blocks 200, 300 may be joined together, and then optical blocks 100, 300 may be joined together. Alternatively, optical blocks 100, 300 may be joined together, and then optical blocks 200, 300 may be joined together. Optical blocks 200, 300 are joined together such that face 312b is coupled to face 212a. Optical blocks 100, 300 are joined together such that face 112b is coupled to face 312a. As a result of the joining (and proper alignment) of optical blocks 100, 200, 300, facet 18 is not parallel to facet 28.

[0104] In certain embodiments, such as the embodiments shown in the figures, optical blocks 100, 200, 300 are arranged such that optical block 300 is positioned between optical blocks 100, 200 such that facet 38 is positioned between facets 18, 28. However, other embodiments are possible in which the order of the optical blocks differs from the order shown in the figures, such as in which optical block 100 is positioned between optical blocks 200, 300 such that facet 18 is positioned between facets 28, 38. In such embodiments, face 312a of optical block 300 forms face 412a of optical block 400.

[0105] The embodiments described so far have been directed to using three optical blocks to form composite optical block 400. However, in certain embodiments, optical block 300 may be omitted or replaced with one or more optical blocks carrying facets in a different orientation than facet 38. Thus, optical block 400 may generally be viewed as being formed of two optical sub-blocks and having two regions, with optical block 200 having facet 28 forming a first sub-block (first region) and optical block 100 having facet 18 forming a second sub-block (second region). In the embodiment shown in the drawings, the second sub-block includes two sub-sub-blocks (two sub-regions), with facet 18 being located in a first sub-sub-block (first sub-region), in which case the first sub-sub-block is optical block 100, and facet 38 being located in a second sub-sub-block (second sub-region), in which case the second sub-sub-block is optical block 300.

[0106] In an embodiment where optical block 300 is omitted, optical blocks 100, 200 are bonded together to form optical block 400 such that face 112b is joined to face 212a. As a result of bonding (and proper alignment) of optical blocks 100, 200, facet 18 is not parallel to facet 28.

[0107] Continue to refer to Figures 1A to 7B , now refer to FIG. 8A to FIG. 9B , which shows the steps for cutting the optical block 400 ( Fig. 8A and Figure 8B ) and the result of cutting the optical block 400 ( Fig. 9A and Fig. 9B ). Generally speaking, if Fig. 8A and Figure 8BAs shown, the optical block 400 is cut along a cutting plane 402 that passes through a face 412a (face 112a in the illustrated embodiment, but may be face 312a in embodiments where the positions of the optical blocks 100 and 300 are interchanged) and at least one of the faces 116a, 216a, 316a. In embodiments where the faces 116a, 216a, 316a are coplanar and form the face 416a, the cutting plane 402 passes through the face 416a. The position of the cutting plane 402 is such that the cutting plane 402 passes through at least a portion of the optical sub-block having facets 18 or facets 38. In the illustrated embodiment, the cutting plane 402 passes through a portion of the optical sub-block having facets 18, which portion of the optical sub-block is the optical block 100 in the illustrated embodiment. However, in some actual implementations, the cutting plane 402 may pass through all three regions of the optical block 400 (i.e., through the region that contains facets 18, 38, 28 in combination).

[0108] In certain embodiments, depending on the configuration of the optical block 400, the cutting plane 402 is tilted relative to the face 412a (112a or 312a), and may also be tilted relative to one or more of the faces 116a, 316a, 412b, 112b, 312a, 312b, 212a. The cutting plane 402 is preferably perpendicular to the face 114a (and thus also perpendicular to the faces 314a, 214a in embodiments where the faces 114a, 314a, 214a are parallel). The result of cutting the optical block 400 along the cutting plane 402 is to form an optical structure 400' having a butt joint surface 404 (or "face" 404) at the location of the cutting plane 402, such as Fig. 9A and Fig. 9B shown.

[0109] The optical block 400 includes FIG. 7A to FIG. 7C In some embodiments of the three optical blocks 100, 200, 300 shown, the position of the cutting plane 402 can be limited so that the cutting plane 402 only passes through a portion of the optical block 100 and does not pass through any of the other optical blocks 200, 300, so that the portion to be cut is only a portion of the optical block 100. However, in other embodiments, the position of the cutting plane 402 can be such that the cutting plane 402 passes through a portion of the optical block 300 and can also pass through a portion of the optical block 200.

[0110] In embodiments where faces 116a, 216a, 316a are coplanar and combine to form face 416a, the portion of optical block 400 that is cut away (i.e., removed) is a triangular prism (typically a right triangular prism) portion (at Fig. 8A and Figure 8BIn embodiments where optical block 300 is sandwiched between optical blocks 100, 200, portion 401 includes a portion (typically all) of face 116a and a portion (which may be a minority, such as approximately 10% to 20%) of face 112a.

[0111] In some embodiments where the positions of the optical blocks 100, 300 are interchanged so that the optical block 100 is sandwiched between the optical block 300 and the optical block 200, the position of the cutting plane can be limited so that the cutting plane 402 only passes through a portion of the optical block 300 and does not pass through any of the other optical blocks 100, 200, so that the portion to be cut is only a portion of the optical block 300. However, similar to the above, in some embodiments, the cutting plane 402 can pass through a portion of the optical block 100 and can also pass through a portion of the optical block 200.

[0112] Fig. 9A and Fig. 9B An optical structure 400' having a butt joint surface 404 is shown resulting from cutting the optical block 400 along a cutting plane 402 and removing the triangular prism portion 401. An optical block 500 having an in-coupled reflector is bonded to the optical structure 400' at the butt joint surface 404.

[0113] The following paragraphs refer to FIG. 10A to FIG. 10D The structure and production of the optical block 500 are described. FIG. 10A to FIG. 10C , the optical block 500 is formed of a light-transmitting material and has a set of reflective inner surfaces 42 (high reflective mirrors), each of which serves as a coupling-in configuration of the final composite LOE. The optical block 500 includes three pairs of faces (main outer surfaces), namely a pair of preferably parallel faces 512a, 512b, a pair of faces 514a, 514b (which may or may not be parallel faces), and a pair of faces 516a, 516b (which may or may not be parallel faces). In certain embodiments, the three pairs of faces of the optical block 500 are mutually orthogonal (perpendicular), however, other embodiments in which the three pairs of faces are not mutually orthogonal may be preferred.

[0114] The optical block 500 may be formed of a plurality of bonded transparent coated plates 502 (each plate formed of a light-transmitting material and coated with a partially reflective coating) to form a reflective inner surface 42 that is obliquely inclined at a predetermined angle to one or both of the surfaces 512a, 512b. There are various known methods for forming the optical block 500. Fig. 10D One such method is shown, in which coated sheets 502 are stacked and joined (similar to Figure 3C , Figure 4C and Figure 5C504 (as in the example of FIG. 505 ), and then cut along equally spaced parallel cutting planes 504 (which are parallel to the yz plane in the arbitrarily labeled xyz coordinate system) to produce cut optical structures 505. One of the optical structures 505 is used to form the optical block 500. Unlike the coating used to produce the facets 18, 28, 38, the coating used to form the coated plate 502 is not partially reflective, but is instead fully (and preferably highly) reflective, so that the resulting interior surface 42 acts as a perfect mirror. A dielectric coating is one example of a suitable coating that can be used to form the reflective interior surface 42. The cutting planes 504 are angled relative to the coated face of the plate 502, wherein the angle of inclination of the planes 504 determines the angle of inclination at which the interior surface 42 is inclined relative to the faces 512a, 512b.

[0115] In some embodiments, each of the optical structures 505 can be cut along two additional parallel planes 506, 508 perpendicular to the plane 504 to form surfaces 514a, 514b so that the optical block 500 has a rectangular cross-section. In the arbitrarily labeled xyz coordinate system, the planes 506, 508 are parallel to the xy plane.

[0116] Continue to refer to 8A to 10D , also concerned about Fig.11A and Fig. 11B , which shows that after being joined together to form an optical structure 600 ( Fig. 12A and Fig. 12B ). Prior to bonding, it is important to properly align the optical block 500 and the optical structure 400' so that the orientation of the inner surface 42 is not parallel to the orientation of the facets 18, 28, 38 (i.e., so that the inner surface 42 is not parallel to the facets 18, 28, 38), and so that each inner surface 42 is associated with a respective one of the LOEs 20 in the optical block 200 so that the projection of the inner surface onto the thickness dimension of the respective LOE (the yz plane in the arbitrarily labeled xyz coordinate system in the drawings) is bounded by the major surfaces 24a, 24b of the LOE 20.

[0117] In certain embodiments, it may also be preferred that each of the faces 514a, 414a is in a plane parallel to the xy plane, and each of the faces 514b, 414b is in a plane parallel to the xy plane.

[0118] To avoid waste in the final cutting step used to cut out the composite LOE, the optical block 500 preferably has the same thickness (measured along the z-axis, i.e., between faces 514a, 514b) as the constituent optical blocks 100, 200, 300, and therefore the same thickness as the optical structure 400'. In such an embodiment, the alignment of the optical block 500 with the optical structure 400' is preferably such that the faces 514a, 414a are coplanar, and similarly, the faces 514b, 414b are coplanar. In such an embodiment, the alignment of the optical block 500 with the optical structure 400' is also such that the faces 512b, 404 are aligned and substantially coincident.

[0119] Once properly aligned, such as Fig. 12A and Fig. 12B As shown, the optical block 500 and the optical structure 400' are joined together to form the optical structure 600 (which is an intermediate work product of the composite LOE manufacturing process). The joining of the optical block 500 and the optical structure 400' causes the face 512b to be coupled to the face (mating surface) 404 while maintaining the above-mentioned alignment. Preferably, the faces 512b, 404 are the same size, or very close to the same size. In some embodiments, the alignment of the optical block 500 and the optical structure 400' can also include twisting or rotating the face 512b relative to the mating surface 404, so that the inner surface 42 is skewed at a certain angle relative to the optical structure 400' in addition to being tilted relative to one or both of the faces 512a, 512b. In the accompanying drawings, such skew angles and tilt angles correspond to the inner surface 42 being tilted at two angles relative to the xy plane.

[0120] like Fig.13As shown, after forming the optical structure 600, the optical structure 600 is cut (sliced) at predetermined intervals along two or more preferably parallel cutting planes 602 to extract one or more composite LOEs. The cutting planes 602 are preferably parallel to the main outer surfaces 24a, 24b of the LOE 20 forming the optical block 200. Most preferably, the continuous cutting planes 602 are located between the surfaces 24a, 24b of the continuous LOE 20, in particular, formed in the bonding area between the surfaces 24a, 24b of the continuous LOE 20. For example, a first cutting plane 602-1 among the cutting planes 602 passes between a junction region between a second surface 24b-1 of a first LOE 20-1 among the LOEs 20 and a first surface 24a-2 of a second LOE 20-2 among the LOEs 20 (adjacent to and joined to the first LOE 20-1), and a second cutting plane 602-2 among the cutting planes 602 adjacent to the first cutting plane 602-1 passes between a junction region between a second surface 24b-2 of the second LOE 20-2 and a first surface 24a-3 of a third LOE 20-3 among the LOEs 20 (adjacent to and joined to the second LOE 20-2). It is noted herein that the junction region (formed between the surfaces 24a, 24b of consecutive LOEs 20) can provide a guide for placing the cutting plane 602. Note also that slight deviations from the parallelism of the cutting planes can be corrected by polishing the composite LOE along both major surfaces, which causes the two major surfaces of the cut composite LOE formed by cutting along the continuous cutting plane 602 to be approximately parallel but not exactly parallel.

[0121] See also FIG. 14A to FIG. 14C, shows a composite LOE 700 cut from an optical structure 600 after cutting along a cutting plane 602. The composite LOE 700 includes: a first pair of opposite faces 712a, 712b (which include portions of faces 412a, 412b, and faces 712a, 712b may or may not be parallel faces); a second pair of parallel faces 714a, 714b (major surfaces) formed by cutting the optical structure 600 along a continuous cutting plane 602 (and preferably formed in part by surfaces 24a, 24b of one of the LOEs 20); and a third pair of opposite faces 716a, 716b (which include portions of faces 416a, 416b, and faces 716a, 716b may or may not be parallel faces). Most notably, the composite LOE 700 has: a first plurality of facets 18 (in a first LOE region 710) having a first orientation and which may also be obliquely inclined relative to or orthogonal to faces 714a, 714b; a second plurality of facets 28 (in a second LOE region 720) which are obliquely inclined relative to faces 714a, 714b and have an orientation that is non-parallel to the orientation of facets 18; and at least one facet 38 located in a region 730 between the first LOE region and the second LOE region and having an orientation that is parallel to faces 714a, 714b and non-parallel to the orientation of facets 18, 28. The composite LOE 700 further comprises a (highly) reflective inner surface 42 (also referred to as an incoupling reflector) which is located in an incoupling region 750 defined by the faces 512a, 514a', 514b', 516a, 516b and has an orientation which is non-parallel to the orientation of the facets 18, 28, 38 (i.e., the reflective inner surface 42 is not parallel to the facets 18, 28, 38). The faces 514a', 514b' are mutually parallel faces and form part of the faces 714a, 714b. In embodiments where the face 512b of the optical block 500 (or the face 512b' of the block 500' or the face 582 of the block 580 / 590) is twisted or rotated relative to the abutment surface 404, the reflective surface 42 is skewed about two axes relative to the waveguide axis (which may be the skew angle measured relative to the x-axis and the y-axis in the xyz coordinate system arbitrarily labeled in the figure).

[0122] It should be obvious that Figures 1A to 2B The composite LOE shown in FIG. 8A to FIG. 12B The cutting and joining steps described above do not provide a composite LOE 700 with a rectangular cross-section in a two-dimensional plane (in Fig. 14B is most obvious in the xy plane shown in ).

[0123] After the composite LOE 700 is cut, each of the composite LOEs can be polished on the outer surfaces 714a, 714b to form a final composite LOE having a desired thickness (measured along the z-axis in the arbitrarily labeled xyz coordinate system in the figures) and to ensure parallelism between the surfaces 714a, 714b (and optional facets 38). Fig.15 One view of the resulting polished composite LOE is shown, where the parallel surfaces 714a', 714b' correspond to the surfaces 714a, 714b after polishing.

[0124] The composite LOE produced using the manufacturing process according to the embodiments disclosed herein provides several advantages over the composite LOE produced using conventional manufacturing methods. First, the cutting plane 402 is positioned at a designated area of ​​the optical block 400 ( Fig. 8A and Figure 8B ) accommodates placement of the in-coupling reflector 42 in an area that presents a more aesthetically pleasing overall design of the composite LOE 700. In addition, the bevel angle of the cutting plane 402 and the cutting plane 504 ( Fig. 10D ) determines the spatial orientation of an image projector that produces collimated image light. In the disclosed embodiments, the spatial orientation of the coupling reflector 42 can be designed to accommodate the spatial positioning of an image projector beneath a composite LOE associated with a portion of the face 714b' located at or near the coupling region 750, thereby providing an aesthetic placement of the image projector and reducing the overall form factor of the optical system formed by the composite LOE and the image projector, which can be implemented as part of a head-mounted display and in certain non-limiting implementations as part of an eyeglass form factor. In addition, the reduced waste of raw materials as achieved by the disclosed manufacturing process and the fact that a large number of composite LOEs can be cut from a single optical structure 600, as compared to conventional manufacturing methods for producing composite LOEs, facilitates large-scale production of composite LOEs while maintaining low manufacturing costs.

[0125] As mentioned, a composite LOE according to the disclosed embodiments can be attached or otherwise coupled to an image projector that produces collimated image light that can be coupled into the composite LOE via the reflective inner surface 42. In a preferred embodiment, the coupling-in reflector is designed to accommodate the spatial positioning of the image projector below the composite LOE. For both functional and aesthetic reasons, it is generally desirable that the collimated image light corresponding to the central field of view chief light should generate approximately perpendicular angles (up to approximately 20°) relative to the composite LOE at the input from the image projector to the composite LOE (i.e., input to the first LOE region via coupling from the reflective inner surface 42) and at the output of the composite LOE to the observer's eye (i.e., output from the second LOE region via the facet 28). Therefore, it is preferred that the reflective inner surface 42 and the facet 28 have similar elevation angles. In other words, the slant angle of reflective interior surface 42 measured relative to faces 512a, 512b is generally approximately equal to the slant angle of facet 28 measured relative to faces 714a', 714b' (or the slant angle of facet 28 equivalently measured relative to surfaces 24a, 24b constituting LOE 20 forming a composite LOE).

[0126] In many cases, only a portion of the reflective interior surface 42 provides a useful active area for coupling light from the image projector into the composite LOE, while the remainder of the reflective interior surface 42 either does not couple any light into the composite LOE or couples light at angles that produce undesirable reflections at the major surfaces of the composite LOE that cause ghost images. Fig. 10D ) are typically high cost, and thus reduction of any unused (i.e., "non-active") area of ​​the interior surface 42 can reduce manufacturing costs. Therefore, to reduce manufacturing costs and mitigate ghost images by preventing or reducing undesired reflections, it may be advantageous to limit the size of the reflective interior surface 42 to the active area and fill the remaining area with a less expensive, inert material (e.g., glass, plastic, or even metal).

[0127] See also FIG. 16A to FIG. 18B, the following paragraphs describe embodiments in which the reduced size reflective interior surface 42 is produced by a reduced size optical block 500' joined together with one or more blocks 800, 900 of an inert material such as, for example, glass, plastic, metal. The materials used to form the blocks 800, 900 (interchangeably referred to herein as "inert blocks") can be the same or different. For example, both blocks 800, 900 can be formed of glass, or one of the blocks can be formed of glass and the other of plastic. The optical block 500' is similar in structure to the optical block 500, with the noted exception that the length of the optical block 500' (which is measured along the y-axis in the arbitrarily labeled xyz coordinate system in the drawings) is reduced compared to the length of the optical block 500, thereby limiting the size of the interior surface 42 to only the useful active area. Due to the similarity in the structure of the optical blocks 500', 500, the same reference numerals will be used to identify the same components, with a prime ("'") appended to the reference numeral of the optical block 500'.

[0128] The inert block 800 has three pairs of faces (major outer faces), namely a first pair of preferably parallel faces 812a, 812b, a second pair of faces 814a, 814b (which may or may not be parallel faces), and a third pair of faces 816a, 816b (which may or may not be parallel faces). The optical block 500' is limited in size by the inert block 800, and thus the inert block 800 can be understood to function as a ghost reduction element that limits the size of the inner surface 42 to only the useful active area. In some embodiments, the block 800 is a rectangular cube.

[0129] The inert block 900 also has three pairs of parallel faces (major outer surfaces), namely a first pair of preferably parallel faces 912a, 912b, a second pair of opposite faces 914a, 914b (which may or may not be parallel faces), and a third pair of opposite faces 916a, 916b (which may or may not be parallel faces). In certain embodiments, the block 900 is a rectangular cube. As will be discussed, the block 900 is optional, but may be advantageously used to provide structural reinforcement and support for the optical block 500'.

[0130] The bonding is preferably performed in stages, where the optical block 500' and the block 800 are first bonded together to form the composite block 580. The blocks 500', 800 are properly aligned before bonding them together. Fig.16A and Fig. 16B800 (when each of blocks 500', 800 is constructed as a rectangular cube) can be understood as follows: faces 512a', 812a are in a plane parallel to the yz plane and are preferably coplanar, faces 512b', 812b are in a plane parallel to the yz plane and are preferably coplanar, faces 514a', 814a are in a plane parallel to the xy plane and are preferably coplanar, faces 514b', 814b are in a plane parallel to the xy plane and are preferably coplanar, and faces 516b', 816a are aligned and coincident in a plane parallel to the xz plane.

[0131] Blocks 500', 800 are joined together to form composite block 580 such that face 516b' is joined to face 816a while maintaining reference Fig.16A and Fig. 16B described alignment. Fig.17A and Fig. 17B Block 580 is shown in FIG. 5 and has: a first pair of preferably parallel faces 582a, 582b formed by faces 512a', 812a and 512b', 812b, respectively; a second pair of faces 584a, 584b formed by faces 514a', 814a and 514b', 814b, respectively (which may or may not be parallel faces); and a third pair of faces 516a', 816b (which may or may not be parallel faces). Inner surface 42 is in a first region of block 580 and is obliquely inclined relative to faces 582a, 582b.

[0132] In some embodiments, the blocks 580, 900 may then be joined together to form a composite block 590, such as Fig.18A and Fig.18B As shown. Before the blocks 580 and 900 are joined together, they are properly aligned. Fig.17A and Fig. 17B 14. Referring to the coordinate system shown, the alignment of blocks 580, 900 (when each of blocks 580, 900 is constructed as a rectangular cube) can be understood as follows: faces 516a', 916a are in a plane parallel to the xz plane and are preferably coplanar, faces 516b', 916b are in a plane parallel to the xz plane and are preferably coplanar, faces 584a, 914a are in a plane parallel to the xy plane and are preferably coplanar, faces 584b, 914b are in a plane parallel to the xy plane and are preferably coplanar, and faces 582a, 912b are aligned and coincident in a plane parallel to the yz plane.

[0133] Blocks 580, 900 are joined together to form composite block 590 such that face 912b is joined to face 582a while maintaining reference Fig.17A and Fig. 17B described alignment. Fig.18A and Fig.18B Block 590 is shown in the figure and has: a first pair of parallel faces 912a, 582b; a second pair of faces 594a, 594b formed by faces 914a, 584a and 914b, 584b, respectively (which may or may not be parallel faces); and a third pair of faces 596a, 596b formed by faces 916a, 586a and 916b, 586b, respectively (which may or may not be parallel faces).

[0134] Then, similar to the reference FIG. 11A to FIG. 12B As described, block 590 may be aligned and joined to optical structure 400' in place of optical block 500. When block 590 is used in place of block 500, block 590 is joined to optical structure 400' such that face 582b is coupled to abutment surface 404, as shown in FIG. Fig.19A and Fig.19B Thus, only a small portion of the abutment surface 404 is coupled to the face 512b' (which forms part of the face 582b). Fig. 12A and Fig. 12B In contrast to the embodiment shown, Fig. 12A and Fig. 12B In the embodiment shown in , all of face 512b is bonded to all of abutment surface 404. The optical structure formed by joining block 590 and optical structure 400' together can then be sliced ​​at predetermined intervals bounded by parallel cutting planes to extract one or more composite LOEs, similar to reference Fig.13 As described.

[0135] In certain embodiments, the inert block 900 may be joined without the inert block 800 to provide structural reinforcement and support to the optical block 500. For example, in one embodiment, the inert block 900 and the optical block 500 are joined together to form an intermediate block such that the face 912b is coupled to the face 512a of the optical block 500. In such an embodiment, the inert block 900 and the optical block 500 are properly aligned before joining them together.

[0136] In another similar embodiment, the inert block 900 and the optical block 500' are joined together without the presence of the block 800. In such an embodiment, the joining causes the face 912b to be coupled to the face 512a' of the optical block 500'. In such an embodiment, the inert block 900 and the optical block 500' are properly aligned before joining them together. Optionally, the size of the inert block 900 can be reduced to match the size of the optical block 500'.

[0137] In certain embodiments, it may be desirable to cut out a composite LOE (e.g. Fig.15A transparent cover is provided on one or both polished surfaces 714a', 714b' of the composite LOE (shown in FIG. 1 ). In certain embodiments, such a transparent cover can be provided directly to the surfaces 714a', 714b' (ie, after the cut composite LOE is polished).

[0138] In other embodiments, Fig. 20A and Fig. 20B As shown, a transparent cover plate can be provided as a spacer between LOEs 20 during the production of the optical block 200. Fig. 20A , shows an aligned arrangement 220 of LOE 20 and transparent cover plate 220, wherein LOE 20 and cover plate 230 alternate along a length of the arrangement 220 perpendicular to the parallel faces 24a, 24b of LOE 20 (here the length is along the z-axis). Each cover plate 230 has a pair of parallel outer faces 231a, 231b. Fig. 20B As shown, the cover plates 230 and LOE 20 are bonded together to form a bonded stack 200 ′ (also referred to as an optical block 200 ′). The bonding allows adjacent cover plates 230 and LOE 20 faces 231 b and 24 a to bond, and adjacent cover plates 230 and LOE 20 faces 231 a and 24 b to bond.

[0139] The stack 200' is generally similar in structure to Figure 3A 214a, 214b (and parallel to the faces 212a, 212b) of the stack 200 '. These transparent cover plates 230 are also referred to as transparent spacer plates because they provide spacing between consecutive LOEs.

[0140] In an embodiment in which an optical block 200' is provided having LOEs 20 provided with spacer plates 230 between the LOEs 20, the thickness of the coating plate 302 used in forming the optical block 300 should be adjusted to take into account the overall thickness of the optical block 200' and ensure that the alignment of the optical blocks 200', 300 is such that each facet 38 is located in a plane midway between the major surfaces 24a, 24b of the associated LOE 20, so that the optical blocks 200', 300 are joined together in proper alignment. In addition, as Fig.21As shown, when performing a cutting step to cut out composite LOEs with optical block 200 ′ instead of optical block 200 , consecutive cutting planes should pass through consecutive spacer plates 230 with one of LOEs 20 therebetween, and preferably pass approximately through the center of the spacer plate 230 .

[0141] exist Fig. 22 An example of a cut-out composite LOE 700 having two transparent cover sheets 232, 234 is shown in . The cover sheets 232, 234 are formed by two of the cover sheets 230 in the stack 200' being sliced ​​along two of the cutting planes 602. The cover sheets 232, 234 are joined to the LOE 20 such that the face 231b of the cover sheet 232 is coupled to the face 24a of the LOE 20, and the face 231a of the cover sheet 234 is coupled to the face 24b of the LOE 20. The face 233a of the cover sheet 232 (which is the face opposite the face 231b of the cover sheet 232) and the face 233b of the cover sheet 234 (which is opposite the face 231a of the cover sheet 234) form a portion of the major outer surfaces 714a, 714b of the composite LOE 700, respectively. Similar to the above reference to Fig.15 Then, we can Fig. 22 The surfaces 714a, 714b of the composite LOE are polished to obtain a final composite LOE having a desired thickness and to ensure parallelism between the surfaces 714a, 714b.

[0142] Although the embodiments described herein have been directed to coupling the optical block 500 (or 500') to the optical structure 400' such that the in-coupling reflector 42 accommodates the spatial positioning of the image projector below the final composite LOE product, other embodiments that accommodate different spatial positioning of the image projector are possible. For example, the optical block 500 may be inverted (e.g., by swapping the positions of the surfaces 514a, 514b) such that the inner surface 42 is tilted upward, rather than downward as in FIG. Fig. 10A , Fig. 10B , Fig.11A and Fig. 12A Such a configuration allows the image projector to be deployed above the final composite LOE product.

[0143] Although not shown in the figures, additional optical components such as prisms may be optically coupled or bonded to the optical block 500 (or 500') with or without the inert blocks 800 and / or 900 before the composite LOE is cut out to provide additional coupling-in geometry for the final composite LOE product. Alternatively, one or more additional optical components such as prisms may also be optically coupled or bonded to the coupling-in reflector 42 at the coupling-in region 750.

[0144] The present disclosure has described various cutting steps in which optical materials are cut along cutting planes to produce various optical blocks and sub-components of optical blocks. It is noted that in some embodiments, some or all of the surfaces produced by these cutting steps can be polished before the bonding step. For example, the joining surfaces of the optical blocks 100, 200, 300 can be polished before the optical blocks 100, 200, 300 are bonded together. In addition, the main surface of the LOE used to form the optical block 200 can be polished before forming the stack of bonded LOEs (optical block 200). In addition, the docking surface 404 and the joining surface of the optical block 500 can be polished before the optical blocks 400, 500 are bonded together.

[0145] The alignment of the various blocks and structures described herein may be performed using any suitable optical alignment equipment / devices / tools that implement suitable optical alignment techniques / methods. Such suitable optical alignment equipment / devices / tools may include, for example, one or more computerized control devices, one or more computerized processing devices, one or more optical subsystems having, for example, one or more light sources, one or more light detectors / sensors, one or more optical devices (e.g., one or more lenses, folded optical devices, etc.), autocollimators, etc. Details of non-limiting examples of suitable optical alignment equipment / devices / tools / methods that can be used to align the various blocks and structures described herein can be found in various publications of Lummus Ltd. (Israel), including, for example, International Patent Application No. PCT / IL2021 / 051377 and International Patent Application No. PCT / IL2021 / 051378, which were not published before the filing date of the present application and do not constitute prior art.

[0146] As will be appreciated by one of ordinary skill in the art, the cutting or slicing of the optical blocks and optical structures described herein may be performed by any suitable cutting equipment / device / tool. As will be appreciated by one of ordinary skill in the art, the polishing of the faces and surfaces of the optical blocks and optical structures (including composite LOEs) described herein may be performed by any suitable polishing equipment / device / tool.

[0147] Although the embodiments described so far have involved joining together two or three optical blocks carrying two or three groups of facets, respectively, in prescribed orientations to accommodate the deflection of light in prescribed directions, other embodiments are contemplated herein in which one or more additional optical blocks carrying one or more groups of additional facets or optical retarders (e.g., one or more wave plates) in prescribed orientations are joined to the aforementioned optical blocks. The scope of the present invention should not be limited to any particular number of the aforementioned optical blocks.

[0148] Descriptions of various embodiments of the present disclosure have been presented for illustrative purposes, but the descriptions are not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terms used herein are selected to best illustrate the principles of the embodiments, practical applications, or technical improvements over technologies found on the market, or to enable those of ordinary skill in the art to understand the embodiments disclosed herein.

[0149] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0150] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations and / or to exclude the incorporation of features from other implementations.

[0151] It should be understood that certain features of the invention described in the context of separate embodiments for the sake of clarity may also be provided in combination in a single embodiment. Conversely, various features of the invention described in the context of a single embodiment for the sake of brevity may also be provided in any other described embodiment of the invention, either individually or in any suitable sub-combination or as desired. Certain features described in the context of various embodiments should not be considered essential features of those embodiments, unless the embodiment is inoperable without those elements.

[0152] To the extent that the appended claims are drafted without multiple references, this is done solely to accommodate formal requirements in jurisdictions that do not permit such multiple references. It should be noted that all possible combinations of features implied by making claims multiple references are expressly contemplated and should be considered part of the present invention.

[0153] Although the present invention has been described in conjunction with specific embodiments of the present invention, it is apparent that many substitutions, modifications and variations will be apparent to those skilled in the art. Therefore, it is intended to cover all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

Claims

1. A method for manufacturing a composite light guide optical element (LOE), comprising: obtaining a stack having a first facing surface 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 inner surfaces inclined relative to the pair of major parallel surfaces; obtaining a first optical block having a second opposing surface and a second plurality of partially reflective inner surfaces parallel to each other; bonding the first optical block and the stack together such that one of the first opposing faces is coupled to a first of the second opposing faces and such that the first plurality of partially reflective interior surfaces is non-parallel to the second plurality of partially reflective interior surfaces to form a second optical block; cutting the second optical block along a cutting plane passing through a second face of the second pair of opposite faces, thereby forming a first optical structure having a butting surface at the cutting plane; obtaining a third optical block having a third opposite surface and a plurality of mutually parallel reflective inner surfaces; bonding the third optical block and the first optical structure together so that a first face of the third pair of opposing faces is coupled to the butting surface and so that the plurality of reflective inner surfaces are not parallel to the first plurality of partially reflective inner surfaces and the second plurality of partially reflective inner surfaces, thereby forming a second optical structure; as well as At least one composite LOE is cut out of the second optical structure by cutting the second optical structure via at least two cutting planes that are substantially parallel to major parallel surfaces of consecutive LOEs of the plurality of LOEs.

2. The method according to claim 1, further comprising: For each cut composite LOE of the at least one composite LOE, an outer surface of the cut composite LOE formed by cutting the second optical structure along two consecutive cutting planes of the at least two cutting planes is polished.

3. The method according to claim 1, wherein: The first optical block has a pair of parallel faces, and wherein the second plurality of partially reflective interior surfaces are perpendicular to the pair of parallel faces of the first optical block.

4. The method according to claim 1, wherein: The first optical block has a pair of parallel faces, and wherein the second plurality of partially reflective interior surfaces are tilted relative to the pair of parallel faces of the first optical block.

5. The method according to claim 1, wherein: The first optical block has a third plurality of partially reflective inner surfaces that are parallel to each other and are non-parallel to the first plurality of partially reflective inner surfaces and the second plurality of partially reflective inner surfaces.

6. The method according to claim 5, wherein: The first optical block has a first region including the second plurality of partially reflective inner surfaces and a second region including the third plurality of partially reflective inner surfaces, wherein the first region and the second region of the first optical block are non-overlapping regions.

7. The method according to claim 5, wherein: The third plurality of partially reflective interior surfaces are parallel to the major parallel surfaces of the plurality of LOEs.

8. The method according to claim 5, wherein: Each individual partially reflective interior surface of the third plurality of partially reflective interior surfaces is located in a plane approximately midway between a pair of major parallel surfaces of a corresponding one of the LOEs of the plurality of LOEs.

9. The method according to claim 5, wherein: The third plurality of partially reflective interior surfaces is located between the first plurality of partially reflective interior surfaces and the second plurality of partially reflective interior surfaces.

10. The method according to claim 5, wherein: The second plurality of partially reflective interior surfaces is located between the first plurality of partially reflective interior surfaces and the third plurality of partially reflective interior surfaces.

11. The method according to claim 1, wherein: The first optical block is formed by bonding together a first constituent optical block and a second constituent optical block, each having a pair of opposite faces, so that one of the opposite faces of the first constituent optical block is coupled to one of the opposite faces of the second constituent optical block, wherein the first constituent optical block includes a second plurality of partially reflective inner surfaces, and wherein the second constituent optical block includes a third plurality of partially reflective inner surfaces that are parallel to each other and are not parallel to the first plurality of partially reflective inner surfaces and are not parallel to the second plurality of partially reflective inner surfaces.

12. The method according to claim 1, wherein: The third optical block and the first optical structure are bonded together such that substantially all of a first one of the third pair of opposing faces is coupled to substantially all of the abutment surface.

13. The method according to claim 1, wherein: The third optical block and the first optical structure are bonded together such that a first one of the third pair of opposing faces is coupled to a portion of the abutting surface.

14. The method according to claim 1, wherein: The third optical block has an additional pair of faces, the method further comprising: obtaining an inert block having a first facing surface and a second facing surface; The inert block and the third optical block are joined together such that one of the first opposing faces of the inert block is coupled to one of the additional pair of opposing faces of the third optical block, thereby forming a composite block having a first face and a second face, wherein the first face of the composite block is formed by one of the first and second opposing faces of the third opposing faces of the inert block, and the second face of the composite block is formed by one of the second and second opposing faces of the third opposing faces of the inert block.

15. The method according to claim 14, further comprising: obtaining a second inert block, the second inert block having a pair of faces; and joining the second inert block and the composite block together such that one of the pair of faces of the second inert block is coupled to a second face of the composite block.

16. The method according to claim 14, wherein: Bonding the third optical block and the first optical structure together includes bonding the composite block and the first optical structure together such that a first face of the composite block is coupled to the abutment surface.

17. The method according to claim 1, further comprising: obtaining an inert block having a pair of faces; and The inert block and the third optical block are bonded together such that one of the pair of opposing surfaces of the inert block is coupled to a second of the third pair of opposing surfaces of the third optical block.

18. The method according to claim 1, wherein: The stack is a joined stack of the LOE and a plurality of transparent spacer plates, wherein the LOE and the transparent spacer plates alternate along a length of the stack perpendicular to the major parallel surfaces of the LOE.

19. The method according to claim 18, wherein: The at least two cutting planes are located in consecutive spacer plates with one of the LOEs therebetween.

20. A method for manufacturing a composite light-guiding optical element (LOE): A first optical block is obtained, wherein the first optical block comprises: At least the first one. a first region formed by 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, the set of mutually parallel partially reflective internal surfaces being located between the parallel surfaces and obliquely inclined relative to the parallel surfaces, such that the first region includes a first plurality of partially reflective internal surfaces, and a second region having a second plurality of mutually parallel partially reflective interior surfaces that are non-parallel to the first plurality of partially reflective interior surfaces; cutting the first optical block along a cutting plane passing through one of the first opposing faces, thereby forming a first optical structure having a butt joint surface at the cutting plane; obtaining a second optical block having a second opposite surface and a plurality of mutually parallel reflective inner surfaces; bonding the first optical structure and the second optical block together such that one of the second opposing surfaces is coupled to the abutting surface and such that the plurality of reflective inner surfaces are not parallel to both the first plurality of partially reflective inner surfaces and the second plurality of partially reflective inner surfaces, thereby forming a second optical structure; as well as At least one composite LOE is cut out of the second optical structure by cutting the second optical structure via at least two cutting planes that are substantially parallel to the main parallel surfaces of consecutive LOEs of the stack of LOEs.

21. The method according to claim 20, wherein: The first optical block also includes an additional pair of faces, wherein one of the main parallel surfaces of the LOEs of the stack of LOEs at the top end of the stack of LOEs forms a part of a first face of the additional pair of faces, and one of the main parallel surfaces of the LOEs of the stack of LOEs at the bottom end of the stack of LOEs forms a part of a second face of the additional pair of faces.

22. The method according to claim 20, wherein: The second area includes a first sub-block area and a second sub-block area, wherein the second plurality of partially reflective inner surfaces are located in the first sub-block area, wherein a third plurality of mutually parallel partially reflective inner surfaces are located in the second sub-block area, and wherein the third plurality of partially reflective inner surfaces are not parallel to the first plurality of partially reflective inner surfaces and are not parallel to the second plurality of partially reflective inner surfaces.

23. The method according to claim 22, wherein: The third plurality of partially reflective interior surfaces is located between the first plurality of partially reflective interior surfaces and the second plurality of partially reflective interior surfaces.

24. The method according to claim 22, wherein: The second plurality of partially reflective interior surfaces is located between the first plurality of partially reflective interior surfaces and the third plurality of partially reflective interior surfaces.

25. A method for manufacturing a composite light-guiding optical element (LOE): obtaining a first optical block having a first facing surface and a first plurality of partially reflective inner surfaces parallel to each other; 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 principal parallel surfaces and a second plurality of mutually parallel partially reflective inner surfaces inclined relative to the pair of principal parallel surfaces; obtaining a third optical block having a third pair of opposing faces and a third plurality of partially reflective inner surfaces parallel to one another; The first optical block and the third optical block are bonded together and the second optical block and the third optical block are bonded together to form a fourth optical block, wherein the bonding is such that: i) a first surface of the first pair of surfaces is coupled to a first surface of the third pair of surfaces, ii) one of the second opposing faces is coupled to a second of the third opposing faces, iii) the third plurality of partially reflective interior surfaces are substantially parallel to the major parallel surfaces of the LOE, and iv) the first plurality of partially reflective internal surfaces, the second plurality of partially reflective internal surfaces and the third plurality of partially reflective internal surfaces are not parallel to each other; cutting the fourth optical block along a cutting plane passing through a second surface of the first pair of opposite surfaces, thereby forming a first optical structure having a butt joint surface at the cutting plane; obtaining a fifth optical block having a fourth opposite surface and a fourth plurality of mutually parallel reflective inner surfaces; bonding the first optical structure and the fifth optical block together to form a second optical structure, wherein the first optical structure and the fifth optical block are bonded together such that one of the fourth opposing surfaces is coupled to the butting surface, and such that the fourth plurality of reflective internal surfaces are not parallel to the first plurality of partially reflective internal surfaces, the second plurality of partially reflective internal surfaces, and the third plurality of partially reflective internal surfaces; and At least one composite LOE is cut out of the second optical structure by cutting the second optical structure via at least two cutting planes that are substantially parallel to major parallel surfaces of consecutive LOEs in the stack of LOEs.

26. A method for manufacturing a composite light-guiding optical element (LOE): obtaining a first optical block having a first facing surface and a first plurality of partially reflective inner surfaces parallel to each other; 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 principal parallel surfaces and a second plurality of mutually parallel partially reflective inner surfaces inclined relative to the pair of principal parallel surfaces; obtaining a third optical block having a third pair of opposing faces and a third plurality of partially reflective inner surfaces parallel to one another; The first optical block and the third optical block are bonded together and the first optical block and the second optical block are bonded together to form a fourth optical block, wherein the bonding is such that: i) a first surface of the third opposing surfaces is coupled to a first surface of the first opposing surfaces, ii) one of the second opposing faces is coupled to a second of the first opposing faces, iii) the third plurality of partially reflective interior surfaces are substantially parallel to the major parallel surfaces of the LOE, and iv) the first plurality of partially reflective internal surfaces, the second plurality of partially reflective internal surfaces and the third plurality of partially reflective internal surfaces are not parallel to each other; cutting the fourth optical block along a cutting plane passing through a second surface of the third pair of opposite surfaces, thereby forming a first optical structure having a butt joint surface at the cutting plane; obtaining a fifth optical block having a fourth opposite surface and a plurality of mutually parallel reflective inner surfaces; bonding the first optical structure and the fifth optical block together to form a second optical structure, wherein the first optical structure and the fifth optical block are bonded together such that one of the fourth opposing surfaces is coupled to the butting surface and such that the plurality of reflective inner surfaces are not parallel to the first plurality of partially reflective inner surfaces, the second plurality of partially reflective inner surfaces, and the third plurality of partially reflective inner surfaces, thereby forming the second optical structure; and At least one composite LOE is cut out of the second optical structure by cutting the second optical structure via at least two cutting planes that are substantially parallel to major parallel surfaces of consecutive LOEs in the stack of LOEs.

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