Method for fabricating a composite optical element having an embedded coupled reflector.

Abstract

Improvements are needed in the method for producing composite LOEs. [Solution] The stack has a plurality of LOEs, each having first and second faces, and two parallel main faces and a first plurality of parallel internal facets oblique to the main faces. The first block has third and fourth faces and a second plurality of parallel internal facets. The first block and the stack are joined so that the second face connects to the third face and the first and second facets are non-parallel to form a second block. The second block is cut by a plane passing through the first face to form a first structure having an interface face. The third block has fifth and sixth faces, and a plurality of parallel internal reflectors. The third block and the first structure are joined so that the fifth face connects to the interface face and the internal reflectors are non-parallel to all facets to form a second structure. The composite LOE is cut from the second structure.

Description

Technical Field

[0001] Cross - Reference to Related Applications This application claims priority to U.S. Provisional Patent Application No. 63 / 235,837, filed Aug. 23, 2021, the disclosure of which is incorporated herein by reference in its entirety.

[0002] The present invention relates to a light - guiding optical element (LOE), and more particularly, to a method for manufacturing a composite LOE for two - dimensional aperture expansion having an embedded coupling reflector.

Background Art

[0003] Composite LOEs or “two - dimensional expanded waveguides” have been described in various publications by Lumus Ltd (Israel). Generally, these composite LOEs utilize two regions, each of which is a parallel - faced block of a transparent material (i.e., a light - transmissive material) for facilitating the propagation of light corresponding to a collimated image by internal reflection on the main surface, and includes a set of mutually parallel internal partially - reflective surfaces (i.e., “facets”) that change the direction of the light of the collimated image while achieving an expansion of the optical aperture. By combining two such elements with different facet orientations, a two - dimensional expansion of the optical aperture can be realized within a single composite element, thereby expanding an input image from an image projector and outputting the expanded image over a larger area towards the observer's eyes.

Summary of the Invention

[0004] Embodiments of the present invention provide a method for fabricating a composite LOE.

[0005] According to the teaching of embodiments of the present invention, a method for fabricating a composite optical element (LOE) is provided. The method involves obtaining a stack having a first pair of faces and a plurality of LOEs, wherein each LOE has a pair of principal parallel faces and a first plurality of mutually parallel partially reflective inner surfaces oblique to the pair of principal parallel faces; obtaining a first optical block having a second pair of faces and a second plurality of mutually parallel partially reflective inner surfaces; joining the first optical block and the stack together such that one of the faces of the first pair of faces is connected to one of the faces of the second pair of faces, and the first plurality of partially reflective inner surfaces are non-parallel to the second plurality of partially reflective inner surfaces, thereby forming a second optical block; and cutting the second optical block along a cutting plane passing through the other of the faces of the second pair of faces. The method includes: cutting to form a first optical structure having an interface surface at the cut surface; obtaining a third optical block having a third pair of surfaces and a plurality of mutually parallel reflective inner surfaces; joining the third optical block and the first optical structure together such that one of the surfaces of the third pair of surfaces is connected to the interface surface and the plurality of reflective inner surfaces are non-parallel to both the plurality of partial reflective inner surfaces of the first and the plurality of partial reflective inner surfaces, thereby forming a second optical structure; and cutting the second optical structure through at least two cut surfaces that are substantially parallel to the principal parallel planes of a continuous LOE, thereby cutting out at least one composite LOE from the second optical structure.

[0006] Optionally, the method further includes polishing the outer surface of each excised composite LOE formed by cutting the optical structure along two consecutive of the cut planes.

[0007] Optionally, the first optical block has a pair of parallel surfaces, and the second plurality of partially reflective inner surfaces are perpendicular to the pair of parallel surfaces of the first optical block.

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

[0009] Optionally, the first optical block has a third plurality of mutually parallel partial reflective inner surfaces that are non-parallel to the first plurality of partial reflective inner surfaces and the second plurality of partial reflective inner surfaces.

[0010] Optionally, the first optical block has a first region including a second plurality of partially reflective inner surfaces and a second region including a third plurality of partially reflective inner surfaces, wherein the first and second regions of the first optical block are non-overlapping regions.

[0011] Optionally, a third group of partially reflective inner surfaces are parallel to the principal parallel planes of the LOE.

[0012] Optionally, each of the third partially reflective inner surfaces lies in a plane approximately midway between each pair of principal parallel planes of the LOE.

[0013] Optionally, a third plurality of partially reflective inner surfaces are located between the first plurality of partially reflective inner surfaces and the second plurality of partially reflective inner surfaces.

[0014] The second plurality of partially reflective inner surfaces are optionally positioned between the first plurality of partially reflective inner surfaces and the third plurality of partially reflective inner surfaces.

[0015] Optionally, first and second constituent optical blocks, each having a pair of faces, are formed by joining the first optical block together such that one of the faces of the pair of faces of the first constituent optical block is connected to one of the faces of the pair of faces of the second constituent optical block, wherein 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.

[0016] The third optical block and the first optical structure are joined together, optionally such that substantially the entirety of one of the faces of the third pair of faces is connected to substantially the entirety of the interface face.

[0017] The third optical block and the first optical structure are joined together, optionally such that one of the faces of the third pair of faces is connected to a portion of the interface face.

[0018] The method further comprises: optionally, a third optical block having an additional pair of faces; obtaining an inert block having first and second pairs of faces; joining the inert block and the third optical block together such that one of the faces of the first pair of faces of the inert block is connected to one of the faces of the additional pair of faces of the third optical block, thereby forming a composite block having first and second faces, wherein the first face of the composite block is formed from 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 pair of faces of the composite block is formed from the other of the faces of the third pair of faces and one of the faces of the second pair of faces of the inert block.

[0019] Optionally, the method further includes 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 faces of the pair of faces of the second inert block is connected to the second face of the composite block.

[0020] Optionally, joining the third optical block and the first optical structure together includes joining the composite block and the first optical structure together such that the first face of the composite block is connected to the interface face.

[0021] Optionally, the method further includes obtaining an inert block having a pair of faces, and joining the inert block and the third optical block together such that one of the faces of the pair of faces of the second inert block is connected to the other of the faces of the third pair of faces of the optical block.

[0022] Optionally, the stack is a bonded stack of LOE and multiple transparent spacer plates, where the LOE and transparent spacer plates are arranged alternately along the length of the stack perpendicular to the principal parallel plane of the LOE.

[0023] Optionally, at least two cross-sections are located on a continuous spacer plate having one of the LOEs between at least two cross-sections.

[0024] According to a teaching embodiment of the present invention, a method for fabricating a composite optical element (LOE) is also provided. This method involves obtaining a first optical block, the first optical block comprising: a first region formed from a stack of LOEs, each of which has a pair of principal parallel faces and a set of mutually parallel partial reflective inner surfaces located between the parallel faces and inclined obliquely with respect to the parallel faces such that the first region includes a first plurality of partial reflective inner surfaces; and a second region having a second plurality of mutually parallel partial reflective inner surfaces non-parallel to the first plurality of partial reflective inner surfaces; and cutting the first optical block along a cutting plane passing through one of the faces of the first pair of faces, thereby at the cutting plane The method includes forming a first optical structure having an interface surface; obtaining a second optical block having a second pair of surfaces and a plurality of mutually parallel reflective inner surfaces; joining the first optical structure and the second optical block together such that one of the surfaces of the second pair of surfaces is connected to the interface surface and the plurality of reflective inner surfaces are non-parallel to both the plurality of partial reflective inner surfaces of the first and the plurality of partial reflective inner surfaces of the second, thereby forming a second optical structure; and cutting the second optical structure through at least two cutting planes that are substantially parallel to the principal parallel planes of a continuous LOE, thereby cutting out at least one composite LOE from the second optical structure.

[0025] Optionally, the stack is a bonded stack of LOE and multiple transparent spacer plates, where the LOE and transparent spacer plates are arranged alternately along the length of the stack perpendicular to the principal parallel plane of the LOE.

[0026] Optionally, at least two cross-sections are located on a continuous spacer plate having one of the LOEs between at least two cross-sections.

[0027] Optionally, the first optical block further includes an additional pair of surfaces, and one of the major parallel surfaces of the LOE at the upper end of the stack forms a part of one of the surfaces of the additional pair of surfaces, and one of the major parallel surfaces of the LOE at the lower end of the stack forms a part of the other surface of the additional pair of surfaces.

[0028] Optionally, the second optical sub-block includes a first sub-block region and a second sub-block region, a second plurality of partially reflective inner surfaces are located within the first sub-block region, a third plurality of mutually parallel partially reflective inner surfaces are located within the second sub-block region, the third plurality of partially reflective inner surfaces are non-parallel to the first plurality of partially reflective inner surfaces and non-parallel to the second plurality of partially reflective inner surfaces.

[0029] Optionally, the third plurality of partially reflective inner surfaces are located between the first plurality of partially reflective inner surfaces and the second plurality of partially reflective inner surfaces.

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

[0031] According to a teaching embodiment of the present invention, a method for fabricating a composite optical element (LOE) is also provided. The method is to obtain a first optical block having a first pair of faces and a first plurality of mutually parallel partially reflective inner surfaces; to obtain a second optical block formed as a stack of LOEs and having a second pair of faces, wherein each LOE has a pair of principal parallel faces and a second plurality of mutually parallel partially reflective inner surfaces oblique to the pair of principal parallel faces; and to obtain a third optical block having a third pair of faces and a third plurality of mutually parallel partially reflective inner surfaces. The joining involves joining the first and third optical blocks together, and joining the second and third optical blocks together to form a fourth optical block, wherein the joining involves i) one face of the first pair of faces being connected to one face of the third pair of faces, ii) one face of the second pair of faces being connected to the other face of the third pair of faces, iii) the third plurality of partially reflective inner surfaces being substantially parallel to the principal parallel planes of the LOE, and iv) the first, second, and third plurality of partially reflective inner surfaces The method includes forming, such that the surfaces are non-parallel to each other; cutting a fourth optical block along a cutting plane passing through the other of the faces of the first pair of faces, thereby forming a first optical structure having an interface surface at the cutting plane; obtaining a fifth optical block having a fourth pair of faces and a plurality of mutually parallel partially reflective inner surfaces; joining the first optical structure and the fifth optical block together to form a second optical structure, wherein joining the first optical structure and the fifth optical block together is such that one of the faces of the fourth pair of faces is connected to the interface surface, and the plurality of reflective inner surfaces are non-parallel to the first, second, and third plurality of partially reflective inner surfaces; and cutting the second optical structure through at least two cutting planes substantially parallel to the principal parallel planes of a continuous LOE, thereby cutting out at least one composite LOE from the second optical structure.

[0032] Optionally, the stack is a bonded stack of LOE and multiple transparent spacer plates, where the LOE and transparent spacer plates are arranged alternately along the length of the stack perpendicular to the principal parallel plane of the LOE.

[0033] Optionally, at least two cross-sections are located on a continuous spacer plate having one of the LOEs between at least two cross-sections.

[0034] According to a teaching embodiment of the present invention, a method for fabricating a composite optical element (LOE) is also provided. This method involves obtaining a first optical block having a first pair of faces 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 pair of faces, wherein each LOE has a pair of principal parallel faces and a second plurality of mutually parallel partially reflective inner surfaces oblique to the pair of principal parallel faces; and obtaining a third optical block having a third pair of faces and a third plurality of mutually parallel partially reflective inner surfaces. The joining of the first and third optical blocks together, and the joining of the first and second optical blocks together, to form a fourth optical block, wherein the joining is such that i) one face of the third pair of faces is connected to one face of the first pair of faces, ii) one face of the second pair of faces is connected to the other face of the first pair of faces, iii) the third plurality of partially reflective inner surfaces are substantially parallel to the principal parallel planes of the LOE, and iv) the first, second, and third plurality of partially reflective inner surfaces are non-parallel to each other. The method includes forming, cutting a fourth optical block along a cutting plane passing through the other of the faces of a third pair of faces, thereby forming a first optical structure having an interface face at the cutting plane, obtaining a fifth optical block having a fourth pair of faces and a plurality of mutually parallel partially reflective inner surfaces, and joining the first optical structure and the fifth optical block together to form a second optical structure, wherein joining the first optical structure and the fifth optical block together is such that one of the faces of the fourth pair of faces is connected to the interface face, and the plurality of reflective inner surfaces are non-parallel to the first, second, and third plurality of partially reflective inner surfaces, forming, thereby forming a second optical structure, and cutting the second optical structure through at least two cutting planes substantially parallel to the principal parallel planes of a continuous LOE, thereby cutting out at least one composite LOE from the second optical structure.

[0035] Optionally, the stack is a bonded stack of LOE and multiple transparent spacer plates, where the LOE and transparent spacer plates are arranged alternately along the length of the stack perpendicular to the principal parallel plane of the LOE.

[0036] Optionally, at least two cross-sections are located on a continuous spacer plate having one of the LOEs between at least two cross-sections.

[0037] Unless otherwise defined herein, all technical and / or scientific terms used herein have the same meaning as commonly understood by those skilled in the art to whom the present invention relates. Methods and materials similar to or equivalent to those described herein may be used in carrying out or testing embodiments of the present invention, but exemplary methods and / or materials are described below. In case of any conflict, the patent specification, including the definitions, shall prevail. In addition, materials, methods, and examples are illustrative and not necessarily intended to be limiting. [Brief explanation of the drawing]

[0038] Some embodiments of the present invention are described herein only as examples, with reference to the accompanying drawings. It should be emphasized that any specific references to the drawings are provided as examples and for illustrative purposes of the exemplary consideration of embodiments of the present invention. In this regard, the description made in conjunction with the drawings will make it clear to those skilled in the art how embodiments of the present invention may be carried out.

[0039] Now, looking at the drawings, similar reference numbers or letters in the drawings indicate corresponding or similar components.

[0040] [Figure 1A] These are schematic side views, a schematic front view, and a schematic top view of a composite LOE, which has a first LOE region having a first set of partially reflective inner surfaces and a second LOE region having a second set of partially reflective inner surfaces that are not parallel to the first set of partially reflective inner surfaces, respectively. [Figure 1B]These are schematic side views, a schematic front view, and a schematic top view of a composite LOE, which has a first LOE region having a first set of partially reflective inner surfaces and a second LOE region having a second set of partially reflective inner surfaces that are not parallel to the first set of partially reflective inner surfaces, respectively. [Figure 1C] These are schematic side views, a schematic front view, and a schematic top view of a composite LOE, which has a first LOE region having a first set of partially reflective inner surfaces and a second LOE region having a second set of partially reflective inner surfaces that are not parallel to the first set of partially reflective inner surfaces, respectively. [Figure 2A] These are schematic side and front views of a composite LOE, similar to the composite LOEs in Figures 1A and 1C, but including a third region having one or more third partially reflective inner surfaces. [Figure 2B] These are schematic side and front views of a composite LOE, similar to the composite LOEs in Figures 1A and 1C, but including a third region having one or more third partially reflective inner surfaces. [Figure 3A] This is a schematic side view of an optical block formed as a bonded stack of LOEs that can be used to form a second LOE region of a composite LOE according to an embodiment of the present invention. [Figure 3B] This is a schematic side view of one of the LOEs of the stack in Figure 3A. [Figure 3C] Figure 3A is a schematic side view of a bonded stack of coated plates that can be cut at predetermined intervals to generate the LOE. [Figure 3D] Figure 3A is a schematic side view of the LOEs placed in the array before joining to form the stack. [Figure 4A] These are a schematic front view and a schematic isometric view, respectively, of an optical block having a plurality of partial reflective surfaces that can be used to form a first LOE region of a composite LOE according to an embodiment of the present invention. [Figure 4B]These are a schematic front view and a schematic isometric view, respectively, of an optical block having a plurality of partial reflective surfaces that can be used to form a first LOE region of a composite LOE according to an embodiment of the present invention. [Figure 4C] Figures 4A and 4B are schematic front views of a bonded stack of coated plates that can be cut at predetermined intervals to produce the optical blocks shown in Figures 4A and 4B. [Figure 5A] These are a schematic front view and a schematic isometric view, respectively, of an optical block having a plurality of partial reflective surfaces that can be used to form a third LOE region of a composite LOE according to an embodiment of the present invention. [Figure 5B] These are a schematic front view and a schematic isometric view, respectively, of an optical block having a plurality of partial reflective surfaces that can be used to form a third LOE region of a composite LOE according to an embodiment of the present invention. [Figure 5C] Figures 5A and 5B are schematic side views of a bonded stack of coated plates that can be cut at predetermined intervals to produce the optical blocks shown in Figures 5A and 5B. [Figure 6A] These are schematic isometric view, schematic front view, and schematic side view, respectively, of the optical blocks shown in Figures 3A, 4A, 4B, 5A, and 5B, aligned before being joined together, according to embodiments of the present invention. [Figure 6B] These are schematic isometric view, schematic front view, and schematic side view, respectively, of the optical blocks shown in Figures 3A, 4A, 4B, 5A, and 5B, aligned before being joined together, according to embodiments of the present invention. [Figure 6C] These are schematic isometric view, schematic front view, and schematic side view, respectively, of the optical blocks shown in Figures 3A, 4A, 4B, 5A, and 5B, aligned before being joined together, according to embodiments of the present invention. [Figure 7A] These are schematic isometric views, schematic front views, and schematic side views corresponding to Figures 6A to 6C, respectively, according to embodiments of the present invention, showing optical blocks joined together to form a new optical block. [Figure 7B]These are schematic isometric views, schematic front views, and schematic side views corresponding to Figures 6A to 6C, respectively, according to embodiments of the present invention, showing optical blocks joined together to form a new optical block. [Figure 7C] These are schematic isometric views, schematic front views, and schematic side views corresponding to Figures 6A to 6C, respectively, according to embodiments of the present invention, showing optical blocks joined together to form a new optical block. [Figure 8A] These are schematic isometric and schematic front views of the cross-sections of the optical blocks shown in Figures 7A and 7C, respectively, used to cut the optical blocks in order to generate a new optical structure according to an embodiment of the present invention. [Figure 8B] These are schematic isometric and schematic front views of the cross-sections of the optical blocks shown in Figures 7A and 7C, respectively, used to cut the optical blocks in order to generate a new optical structure according to an embodiment of the present invention. [Figure 9A] These are schematic isometric and schematic front views of the optical structure formed by cutting the optical structure in Figures 8A and 8B along the cross-section. [Figure 9B] These are schematic isometric and schematic front views of the optical structure formed by cutting the optical structure in Figures 8A and 8B along the cross-section. [Figure 10A] These are schematic isometric, schematic side, and schematic front views, respectively, of an optical block having multiple reflective inner surfaces that can be used to form a combined reflector of a composite LOE according to an embodiment of the present invention. [Figure 10B] These are schematic isometric, schematic side, and schematic front views, respectively, of an optical block having multiple reflective inner surfaces that can be used to form a combined reflector of a composite LOE according to an embodiment of the present invention. [Figure 10C] These are schematic isometric, schematic side, and schematic front views, respectively, of an optical block having multiple reflective inner surfaces that can be used to form a combined reflector of a composite LOE according to an embodiment of the present invention. [Figure 10D]Figures 10A to 10C are schematic side views of a bonded stack of coated plates that can be cut at predetermined intervals to produce the optical blocks shown. [Figure 11A] Figures 9A and 9B show the optical structures according to embodiments of the present invention before they are joined together, and Figures 10A to 10C show a schematic isometric view and a schematic front view of the aligned optical blocks. [Figure 11B] Figures 9A and 9B show the optical structures according to embodiments of the present invention before they are joined together, and Figures 10A to 10C show a schematic isometric view and a schematic front view of the aligned optical blocks. [Figure 12A] These are schematic isometric and schematic front views corresponding to Figures 11A and 11B, respectively, according to embodiments of the present invention, showing optical structures and optical blocks joined together to form a new optical structure. [Figure 12B] These are schematic isometric and schematic front views corresponding to Figures 11A and 11B, respectively, according to embodiments of the present invention, showing optical structures and optical blocks joined together to form a new optical structure. [Figure 13] These are schematic side views of the optical structure shown in Figures 12A and 12B, which show cross-sections at predetermined intervals that allow the optical structure to be cut in order to extract one or more composite LOEs according to an embodiment of the present invention. [Figure 14A] These are schematic side view, schematic front view, and schematic top view of the composite LOE cut out from the optical structure in Figures 12A and 12B, respectively, after cutting the optical structure along the two consecutive cross-sections in Figure 13 according to an embodiment of the present invention. [Figure 14B] These are schematic side view, schematic front view, and schematic top view of the composite LOE cut out from the optical structure in Figures 12A and 12B, respectively, after cutting the optical structure along the two consecutive cross-sections in Figure 13 according to an embodiment of the present invention. [Figure 14C]These are schematic side view, schematic front view, and schematic top view of the composite LOE cut out from the optical structure in Figures 12A and 12B, respectively, after cutting the optical structure along the two consecutive cross-sections in Figure 13 according to an embodiment of the present invention. [Figure 15] This is a schematic side view of the final composite LOE produced from the composite LOE shown in Figures 14A to 14C by polishing two of the main outer surfaces of the composite LOE shown in Figures 14A to 14C according to an embodiment of the present invention. [Figure 16A] These are schematic isometric and schematic front views of a scaled-down optical block similar to the optical blocks shown in Figures 10A and 10C, respectively, aligned with the first and second inert blocks before being joined together with the first inert block according to an embodiment of the present invention. [Figure 16B] These are schematic isometric and schematic front views of a scaled-down optical block similar to the optical blocks shown in Figures 10A and 10C, respectively, aligned with the first and second inert blocks before being joined together with the first inert block according to an embodiment of the present invention. [Figure 17A] These are schematic isometric and front views, respectively, corresponding to Figures 16A and 16B, and show the first inert block and optical block joined together to form the composite block and aligned with the second inert block, before the composite block and the second inert block are joined together according to an embodiment of the present invention. [Figure 17B] These are schematic isometric and front views, respectively, corresponding to Figures 16A and 16B, and show the first inert block and optical block joined together to form the composite block and aligned with the second inert block, before the composite block and the second inert block are joined together according to an embodiment of the present invention. [Figure 18A] These are schematic isometric and schematic front views, corresponding to Figures 17A and 17B, respectively, according to embodiments of the present invention, showing a second inert block and a composite block joined together to form a second composite block. [Figure 18B]These are schematic isometric and schematic front views, corresponding to Figures 17A and 17B, respectively, according to embodiments of the present invention, showing a second inert block and a composite block joined together to form a second composite block. [Figure 19A] These are schematic isometric and schematic front views, respectively, similar to those in Figures 12A and 12B, according to embodiments of the present invention, but they show the composite blocks of Figures 18A and 18B joined together to form an optical structure, and the optical structures of Figures 9A and 9B. [Figure 19B] These are schematic isometric and schematic front views, respectively, similar to those in Figures 12A and 12B, according to embodiments of the present invention, but they show the composite blocks of Figures 18A and 18B joined together to form an optical structure, and the optical structures of Figures 9A and 9B. [Figure 20A] This is a schematic side view similar to Figure 3D, but it shows the LOE arranged in an alternating pattern with multiple transparent cover plates before the LOE and transparent cover plates are joined together, according to an embodiment of the present invention. [Figure 20B] Figure 20A is a schematic side view of alternating LOEs and transparent cover plates joined together to form an optical block that can be used to form a first LOE region of a composite LOE according to an embodiment of the present invention. [Figure 21] This is a schematic side view of an optical structure similar to the optical structure in Figure 13, according to an embodiment of the present invention, but the optical structure includes the optical block shown in Figure 20B. [Figure 22] This is a schematic side view of a composite LOE cut out from the optical structure shown in Figure 21, after cutting the optical structure along two consecutive cutting planes according to an embodiment of the present invention. [Modes for carrying out the invention]

[0041] Embodiments of the present invention provide a method for producing composite LOEs.

[0042] The principles and operation of the method according to the present invention can be better understood by referring to the drawings accompanying this description. The accompanying drawings are optionally labeled, but a consistent xyz coordinate system is provided between each drawing. This xyz coordinate system is used herein to better illustrate the embodiments disclosed by providing a common reference frame between each drawing.

[0043] Before describing in detail at least one embodiment of the present invention, it should be understood that the present invention is not necessarily limited to its application to the construction details and arrangement of components and / or methods described below and / or illustrated in the drawings and / or examples. Other embodiments of the present invention are possible or can be practiced or implemented in various ways.

[0044] Referring here to the drawings, Figures 1A to 1C illustrate various diagrams of composite LOE1. Composite LOE1 includes a first LOE10 and a second LOE20 joined together at the interface surface 40. Typically, the two LOE10 and 20 are manufactured separately and joined together. Throughout this document, the terms “joined” or “bonded” should be understood to mean attached or to be attached using optical adhesive or adhesive or any other suitable adhesive.

[0045] The first LOE 10 is formed from a transparent material and includes a first pair of faces 12a, 12b (which may or may not be parallel), a second pair of faces (main outer faces) 14a, 14b which are a pair of parallel faces, a third pair of faces (main outer faces) 16a, 16b (which may or may not be parallel), and a plurality of mutually parallel partially reflective inner surfaces (also called "facets") 18 that at least partially traverse the LOE 10 between faces 16a and 16b. The LOE 10 is configured to guide light (image illumination) corresponding to a collimated image injected into the LOE 10 by an image projector (not shown), and the light (represented by rays 50 in Figure 1B) is captured in one dimension by internal reflection (preferably, but not limited to, total internal reflection) at the parallel faces 14a, 14b of the LOE 10. LOE10 is further configured to gradually combine the propagating (captured) light from LOE10 via facets 18, which are inclined obliquely to the direction of light propagation, each reflecting a portion 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 diagram, the combined light from LOE10 via facets 18 is represented by rays 60 (Figures 1A and 1B), and the propagation of collimated image light 50 due to internal reflection on the surface of LOE10 is represented by rays 52 in the left and right directions (Figure 1A).

[0046] Generally, facet 18 has a first orientation in composite LOE1. In certain embodiments, facet 18 is angled obliquely with respect to surfaces 14a, 14b. In other embodiments, facet 18 is perpendicular to surfaces 14a, 14b. It should also be noted that in certain embodiments, facet 18 can be angled obliquely with respect to one or both of surfaces 12a, 12b, and in other embodiments, facet 18 can be perpendicular to one or both of surfaces 12a, 12b. In the non-limiting exemplary embodiments illustrated in Figures 1A and 1B, surfaces 12a, 12b are parallel, and facet 18 is inclined obliquely with respect to surfaces 12a, 12b.

[0047] The reflectivity of facet 18 can be provided via a coating on the inner surface before the formation of LOE 10. The reflectivity of each facet 18 may be the same, or the reflectivity of facet 18 may be different from one another and may increase along the direction of light propagation (which is along the y-axis in the xyz coordinate system arbitrarily labeled in the drawing).

[0048] The coupled light from LOE10 is coupled to a second LOE20. LOE20 is also formed from a transparent material and includes a first pair of faces 22a, 22b (which may or may not be parallel), a second pair of faces (primary outer faces) 24a, 24b (which may or may not be parallel), a third pair of faces (primary outer faces) 26a, 26b (which may or may not be parallel), and a plurality of mutually parallel partially reflective inner surfaces ("facets") 28 that are obliquely inclined with respect to faces 24a, 24b. Faces 14a, 24a generally coincide (coplanar) to form a first single outer surface of composite LOE1. Similarly, faces 14b, 24b generally coincide (coplanar) to form a second single outer surface of composite LOE1. Surfaces 16a and 26a also preferably coincide generally (coplanar) to form a third single outer surface of composite LOE1, and surfaces 16b and 26b also preferably coincide generally (coplanar) to form a fourth single outer surface of composite LOE1. The remaining two outer surfaces of composite LOE1 are formed from surfaces 12a and 22b, respectively.

[0049] Facet 28 has a second orientation within the composite LOE 1 that is nonparallel to the first orientation of facet 18. The reflectivity of facet 28 can be provided via a coating on the inner surface before forming LOE 20. The reflectivity of each facet 28 may be the same, or the reflectivity of facet 28 may be different from one another and may increase along the direction of light propagation (which is along the x-axis in an xyz coordinate system arbitrarily labeled in the drawing).

[0050] Light from LOE10 is coupled to LOE20 via interface 40 (coinciding with surfaces 12b and 22a). LOE20 is configured to guide light through internal reflection (preferably total internal reflection, but not limited to) at surfaces 24a and 24b, gradually coupling the propagating light from LOE20 via facets 28, each reflecting a portion of the intensity of the propagating light, thereby extending the image illumination in two dimensions (in this case, along the x-axis). In Figure 1A, the propagation of image light through LOE20 via internal reflection at surfaces 24a and 24b is represented by a set of rays 62 and 63. One of rays 62 and 63 represents the image, and the other of rays 62 and 63 represents the image conjugate corresponding to the light 60 coupled from LOE10 to LOE20. The light coupled from LOE20 by facet 28 is represented in Figure 1A by ray 64.

[0051] Image illumination coupled to the combined LOE1 for induction by LOE10 and LOE20 is generated by an external image projector (not shown), which is typically implemented as a microprojector device formed from a microdisplay device (such as an LCoS chip) that generates image illumination, and a collimating optical system for collimating the image illumination to generate collimated image illumination. The collimated image illumination is coupled into LOE10 by the coupling optical system in the form of a highly reflective inner surface 42 within the coupling region of LOE10.

[0052] To fill the LOE 20 with collimated image illumination while maintaining a small input aperture (small projector), it is preferable to use at least one additional partially reflective inner surface having a specific orientation with respect to the faces 18, 28 and the composite LOE (so that both the image and its conjugate propagate through the LOE by internal reflection). Figures 2A and 2B illustrate a composite LOE having such an additional facet 38. The facet 38 can be deployed as part of the LOE 10 or as part of a separate transparent substrate 30 having three pairs of faces 32a, 32b, 34a, 34b, 36a, 36b (the pair of faces 34a, 34b is a pair of parallel faces), as shown in Figures 2A and 2B. The facet 38 is parallel to faces 14a, 14b, 24a, 24b and therefore has an orientation nonparallel to the orientation of facets 18, 28. When using only a single facet 38, the facet 38 is preferably located midway between faces 24a and 24b (and equivalently, midway between faces 14a and 14b). When using multiple facets 38, it is preferable that the facets 38 are evenly spaced between faces 24a and 24b. In the embodiments illustrated in Figures 2A and 2B, the LOE 10 and the substrate 30 are joined together at faces 12b and 32a, the substrate 30 and the LOE 20 are joined together at faces 22a and 32b, and the facet 38 is positioned between the set of facets 18 and 28. However, it should be noted that other developments are possible, depending on the design specifications for the specific application of the composite LOE, for example, that facet 18 is positioned between the set of facets 38 and 28.

[0053] In the illustrated embodiment, light 60 (coupled by facet 18) is partially reflected by facet 38. The reflective and transmitted portions of light 60 are coupled to LOE 20, corresponding to rays 62 and 63, respectively.

[0054] Further details on composite LOEs, including composite LOEs that may be similar to those illustrated in Figures 1A to 2B, can be found in various publications by Lumus Ltd. (Israel), including, for example, U.S. Patent Application Publication No. 2021 / 0247608, PCT Application No. 2021 / 240513, PCT Application No. 2021 / 152602, PCT Application No. 2021 / 001841, and U.S. Patent No. 10,551,544.

[0055] Embodiments of the present invention relate to a method for manufacturing a composite LOE. A composite LOE manufactured by the method of the present invention may differ in structure from the composite LOE illustrated in Figures 1A to 2B, but will have similar components as will become apparent from the following description. The steps of the manufacturing method will be described in detail below with reference to Figures 3A to 21, and generally include obtaining an optical block 400 having a required set of facets 18, 28 (and preferably also a set of facets 38) embedded in the region of the optical block 400 (Figures 7A to 7C), and the facets 18, 28 (and 38) being appropriately oriented relative to each other so as to be non-parallel to each other, and the optical block 400 having an interface surface (Figures 9A and 9B) formed on a predetermined cross-section (Figures 8A and 8B) at a predetermined angle of the optical block 400 in order to form an optical structure 400' The process includes the steps of cutting a portion of the optical block 400 with a cutting plane passing through a fixed plane, obtaining an additional optical block 500 (Figures 10A to 10D) having a set of reflective inner surfaces 42 embedded therein, and joining the optical block 500 to the optical structure 400' at the interface plane to form an intermediate optical structure 600 (Figures 12A and 12B) having a required set of facets 18 and 28 (and preferably also a set of facets 38) embedded therein, as well as reflective inner surfaces 42 that are non-parallel to the facets 18, 28, and 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), each composite LOE having facets 18 and 28 (and preferably also at least one facet 38), as well as embedded reflective inner surfaces 42. Each of the cut-out composite LOEs can then be polished to obtain a final composite LOE having a desired thickness (Figure 15). In a particular embodiment, one or more blocks 800, 900 of inert material are bonded to an optical block 500 to form a composite block 590 (Figures 16A-18B), and then bonded to an optical structure 400' (Figures 19A and 19B) to form an intermediate optical structure 600.As can be considered, obtaining optical block 400 may involve obtaining various other optical blocks 100, 200, and 300 (Figures 3A to 5C) to produce optical block 400 and joining those optical blocks 100, 200, and 300 together to form optical block 400. Each of the optical blocks 100, 200, and 300 may have one of the required sets of facets 18, 28, and 38 embedded therein and may be produced from a set of joined coated plates cut to the appropriate angles and thicknesses.

[0056] It should be noted that, in the drawings and according to a set of non-limiting embodiments of the present invention, each of the various blocks 100, 200, 300, 400, 500, 800, and 900 is represented as a rectangular cube, i.e., a structure having three pairs of parallel faces that are perpendicular (orthogonal) to each other. However, such representation of the blocks as rectangular cubes is for the purpose of clarity of presentation only, and the parallelism and perpendicularity between all the faces of the individual blocks is not a strict requirement from an optical or manufacturing standpoint. In many embodiments, only one pair of faces of the block needs to be a pair of parallel faces, and the remaining faces may or may not be parallel. In other embodiments, none of the faces of the block need to be a pair of parallel faces.

[0057] The following paragraphs describe the structure and production of the optical block 200 with reference to Figures 3A to 3D. Referring first to Figure 3A, the optical block 200 is shown formed as a stack of LOE 20 joined together. The optical block 200 has at least two pairs of faces (main outer faces), namely, preferably a pair of parallel faces 212a, 212b, and a pair of parallel faces 214a, 214b, which may be orthogonal (perpendicular) to either or both of faces 212a, 212b. The optical block 200 also includes a third pair of faces which may or may not be a pair of parallel faces and which may be perpendicular to one or more of faces 212a, 212b, 214a, 214b. The faces of the third pair are not shown in Figure 3A but are shown in various other drawings, including Figures 6B, 7B, 8B, 9B, 11B, 12B, and 19B. As will become clear, surfaces 214a and 214b can form parts of the upper and lower surfaces of the optical structure 600 (Figures 11C and 11D) from which the composite LOE can be cut out.

[0058] Each of the LOE20s in the stack in Figure 3A is an LOE as illustrated in Figure 3B. This LOE20 is also substantially similar to the second LOE20 discussed above with reference to Figures 1A-2C. As shown in Figure 3B and as discussed above with reference to Figures 1A-2C, each LOE20 is formed from a transparent material having parallel planes 24a, 24b and a set of (multiple) internal facets 28 that are obliquely inclined with respect to planes 24a, 24b. Such an LOE can be used as a standalone LOE (with a suitable coupled optical system) in situations where only one-dimensional aperture expansion is desired. This type of LOE is commonly referred to as a “one-dimensional” LOE, and the structures and methods for manufacturing such one-dimensional LOEs are 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. 2016 / 103263, and PCT Publication No. 2020 / 212835.

[0059] Figure 3C shows one exemplary method for fabricating multiple LOEs 20 that can be used to generate an optical block 200. In Figure 3C, multiple translucent plates are coated, laminated and joined together, and then cut along equally spaced parallel cutting planes 206 (parallel to the xy plane in an arbitrarily labeled xyz coordinate system) to form a coated plate 202. Each of the plates 202 has a pair of parallel faces (surfaces) 204a, 204b that are appropriately coated with a coating that provides reflectivity for the facets 28 (so that the facets 28 are partially reflective). The cutting planes 206 are oblique to the faces 204a, 204b, defining the oblique angles 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 at predetermined intervals. Preferably, the predetermined spacing is uniform, such that the cut surfaces 206 are evenly spaced apart. The uniform spacing is preferably in the range of 1 to 2 millimeters, such that the thickness of each LOE 20 (measured between surfaces 24a and 24b) is about 1 to 2 millimeters.

[0060] Before joining the LOE20 together to form the optical block 200, the LOE20 are first aligned and placed in an array 210 (Figure 3D). The LOE20 in the array 210 are then joined together to form the optical block 200 (Figure 3A) as a joined stack of LOE20 such that adjacent (continuous) faces 24a and 24b of the LOE20 are joined together in the joining region, and that the set of internal facets 28 of the LOE20 constitutes multiple facets 28 of the optical block 200. As can be seen from Figures 3A and 3D, the main face 24a of the LOE20 at the upper end of the stack 200 forms the top surface 214a of the stack 200, and the main face 24b of the LOE20 at the lower end of the stack 200 forms the bottom surface 214b of the stack 200.

[0061] The following paragraphs describe the structure and production of the optical block 100 with reference to Figures 4A to 4C. Referring first to Figures 4A and 4B, the optical block 100 is formed from a transparent material and has a set of embedded facets 18. The optical block 100 includes three pairs of faces (main outer faces), namely, a pair of faces 112a, 112b (which may or may not be parallel faces), preferably a pair of parallel faces 114a, 114b, and a pair of faces 116a, 116b (which may or may not be parallel faces). In certain embodiments, the pairs of faces of the optical block 100 are orthogonal (perpendicular) to each other, which can simplify the manufacturing process.

[0062] The optical block 100 is formed from a plurality of bonded transparent coated plates 102 (each plate is formed from a transparent material and coated with a partially reflective coating) and can form facets 18 that are angled at a predetermined angle with respect to surfaces 114a, 114, i.e., the facets 18 may be obliquely inclined with respect to surfaces 114a, 114b, or perpendicular to surfaces 114a, 114b. The facets 18 may also be obliquely inclined with respect to surfaces 112a, 112b at a predetermined angle. Various known methods exist for forming the optical block 100. Figure 4C illustrates one such method, in which the coated plates 102 are laminated and bonded (similar to Figure 3C), and then cut along a first pair of preferably parallel cutting surfaces 104 and a second pair of preferably parallel cutting surfaces 106 that are preferably perpendicular to the plane 104, in order to extract the optical block 100. In embodiments where facet 18 is oblique to one or both of faces 112a and 112b, the angle of the cutting plane 104 with respect to the face of the coated plate 102 determines the angle at which facet 18 is inclined with respect to faces 112a and 112b. In addition, the cut along cutting plane 104 defines faces 112a and 112b of the optical block 100, and the cut along cutting plane 106 defines faces 116a and 116b of the optical block 100.

[0063] In certain embodiments, such as the embodiment illustrated in Figure 4C, the cross-sections 104 and 106 are perpendicular to the thickness dimension of the plate 102 such that the resulting facets 18 are perpendicular to the faces 114a and 114b of the optical block 100. In the arbitrarily labeled xyz coordinate system used in the drawings, when the cross-sections 104 and 106 are perpendicular to the thickness dimension of the plate 102, cross-section 104 is parallel to the yz plane and cross-section 106 is parallel to the xz plane. Cross-section 106 is perpendicular to plane 104.

[0064] As described above, other embodiments are possible in which the facet 18 is inclined obliquely with respect to surfaces 114a and 114b, so that the cutting surface 106 can be inclined at an appropriate oblique angle with respect to the xz plane to generate an appropriate facet angle with respect to surfaces 114a and 114b.

[0065] The following paragraphs describe the structure and production of the optical block 300 with reference to Figures 5A to 5C. Referring first to Figures 5A and 5B, the optical block 300 is formed from a transparent material and has an embedded set of facets 38. The optical block 300 includes three pairs of faces (main outer faces), namely, a pair of faces 312a, 312b (which may or may not be parallel faces), preferably a pair of 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 300 are orthogonal to each other.

[0066] The optical block 300 is formed from a plurality of bonded transparent coated plates 302 (each plate formed from a transparent material and coated with a partially reflective coating) and can form facets 38 that are parallel to faces 314a, 314b and optionally perpendicular to one or both faces 312a, 312b. Various known methods exist for forming the optical block 300. Figure 5C illustrates one such method, in which the coated plates 302 are stacked and bonded (as in Figures 3C and 4C) and then cut along a pair of cutting surfaces 304 to extract the optical block 100. In certain embodiments, such as the embodiment illustrated in Figure 5C, the plane 304 is a parallel plane (parallel to the yz plane in an optionally labeled xyz coordinate system). However, as mentioned above, parallelism between the planes 304 is not a strict requirement, and in certain cases, cutting along non-parallel cutting planes may be advantageous, which can improve the compactness and overall form factor of the final composite LOE product. In certain embodiments, the planes 304 are perpendicular to the main outer surface (face) of the plate 202. However, this perpendicularity is also not an optical requirement for producing the final composite LOE product, but rather a matter of practical convenience when fabricating the composite LOE. The laminated and joined plates may also be cut along an additional pair of cutting planes 306 passing through two of the plates, which may be parallel to the main outer surface of the plate 202 and perpendicular to the planes 304. In the arbitrarily labeled xyz coordinate system used in the drawings, the cutting planes 306 are parallel to the xy plane.

[0067] Referring to Figures 1A to 5C, and now to Figures 6A to 6C, Figures 6A to 6C show the three optical blocks 100, 200, and 300 before they are bonded together to form optical block 400 (Figures 7A to 7C). Before bonding, it is important that the optical blocks 100, 200, and 300 are properly aligned such that the orientation of facet 18 is non-parallel to the orientation of facet 28, and the orientation of facet 38 is non-parallel to the orientation of facets 18 and 28. In other words, blocks 100, 200, and 300 are aligned such that the facets 18, 28, and 38 are non-parallel to each other.

[0068] Furthermore, it is preferable that the optical block 300 is aligned with the optical block 200 such that the facets 38 of the optical block 300 lie in a plane parallel to the planes of the surfaces 214a and 214b of the optical block 200. In embodiments in which each composite LOE has only a single facet 38, it is preferable that the optical blocks 200 and 300 are aligned such that each of the facets 38 lies in a plane approximately midway between the main outer surfaces 24a and 24b of each of the LOE 20s forming the optical block 200. In embodiments in which each composite LOE has multiple facets 38 (for example, N facets 38), the optical blocks 200 and 300 are preferably aligned with respect to each set of N facets 38, and the N facets 38 are evenly spaced between the main outer surfaces 24a and 24b of each of the LOE 20s forming the optical block 200. However, it should be noted that block 300 can be positioned relative to block 200 without applying excessive scrutiny regarding the positioning of facets 38 relative to the main outer surfaces 24a and 24b, and that mispositioning of facets 38 relative to the main outer surfaces 24a and 24b in the cut composite LOE can be corrected in the final stages of fabrication (typically by polishing or grinding) if there is sufficient reserve area in the cut composite LOE.

[0069] Referring to the coordinate systems shown in Figures 6A to 6C, the alignment of optical blocks 100, 200, and 300 (if each such optical block is constructed as a rectangular cube) can be understood as follows: Each of faces 112a, 212a, and 312a lies in a plane parallel to the yz plane; each of faces 112b, 212b, and 312b lies in a plane parallel to the yz plane; each of faces 114a, 214a, and 314a lies in a plane parallel to the xy plane; each of faces 114b, 214b, and 314b lies in a plane parallel to the xy plane; each of faces 116a, 216a, and 316a lies in a plane parallel to the xz plane; and each of faces 116b, 216b, and 316b lies in a plane parallel to the xz plane. The alignment of optical blocks 100, 200, and 300 also ensures that each of the 38 facets lies in a plane parallel to the xy-plane.

[0070] To reduce waste, optical blocks 100, 200, and 300 are preferably designed to have the same or very similar dimensions, i.e., length, width, and thickness. In the optionally labeled xyz coordinate system in the drawing, the length is measured along the y-axis, i.e., between faces 116a and 116b, between faces 216a and 216b, and between faces 316a and 316b. In the optionally labeled xyz coordinate system in the drawing, the width is measured along the x-axis, i.e., between faces 112a and 112b, between faces 212a and 212b, and between faces 312a and 312b. In the optionally labeled xyz coordinate system in the drawing, the thickness is measured along the z-axis, i.e., between faces 114a and 114b, between faces 214a and 214b, and between faces 314a and 314b.

[0071] Using optical blocks 100, 200, and 300 having the same thickness (or very close to the same thickness) is important to minimize waste from the final cutting step for cutting out the composite LOE. Therefore, in a particularly preferred embodiment, the alignment of optical blocks 100, 200, and 300 is such that faces 114a, 214a, and 314a are coplanar (i.e., in a common plane), faces 114b, 214b, and 314b are coplanar, faces 112a, 212a, and 312a are coplanar, faces 112b, 212b, and 312b are coplanar, faces 116a, 216a, and 316a are coplanar, and faces 116b, 216b, and 316b are coplanar.

[0072] When properly aligned, the optical blocks 100, 200, and 300 are joined together as illustrated in Figures 7A-7C, while maintaining the alignment described with reference to Figures 6A-6C, to form an optical block 400 (a composite optical block composed of multiple subblocks). In the illustrated embodiment, the optical block 400 is a rectangular cube and has three regions: a region having an optical block (stack) 200 carrying LOE 20 joined together with facet 28; another region having an optical block 300 carrying facet 38; and another region having an optical block 100 carrying facet 18. In the illustrated embodiment, the three regions do not overlap, and the three optical blocks 100, 200, and 300 have the same thickness. In such embodiments, faces 112a and 212b form a first pair of parallel faces 412a and 412b of the optical block 400; faces 414a (formed from coplanar faces 114a, 214a, and 314a) and 414b (formed from coplanar faces 114b, 214b, and 314b) form a second pair of parallel faces of the optical block 400; and faces 416a (formed from coplanar faces 116a, 216a, and 316a) and 416b (formed from coplanar faces 116b, 216b, and 316b) form a third pair of parallel faces of the optical block 400. Note that in embodiments where the block 400 is not a rectangular cube, none of the three pairs of faces 412a, 412b, 414a, 414b, 416a, and 416b necessarily have to be a pair of parallel faces.

[0073] As can be seen from Figures 3A, 3D, 7A, and 7D, the main surface 24a of the LOE 20 at the upper end of the stack 200 forms part of the upper surface 414a of the optical block 400, and the main surface 24b of the LOE 20 at the lower end of the stack 200 forms part of the bottom surface 414b of the optical block 400.

[0074] In certain embodiments, optical blocks 100, 200, and 300 can be joined together in stages. For example, optical blocks 200 and 300 may be joined together, and then optical blocks 100 and 300 may be joined together. Alternatively, optical blocks 100 and 300 may be joined together, and then optical blocks 200 and 300 may be joined together. Optical blocks 200 and 300 are joined together such that face 312b connects to face 212a. Optical blocks 100 and 300 are joined together such that face 112b connects to face 312a. As a result of joining (and proper alignment) of optical blocks 100, 200, and 300, facet 18 is non-parallel to facet 28.

[0075] In certain embodiments, such as those illustrated in the drawings, the optical blocks 100, 200, and 300 are arranged such that optical block 300 is positioned between optical block 100 and optical block 200, resulting in facet 38 being positioned between facet 18 and facet 28. However, other embodiments are possible in which the order of the optical blocks differs from that shown in the drawings, for example, in which optical block 100 is positioned between optical block 200 and optical block 300, resulting in facet 18 being positioned between facet 28 and facet 38. In such embodiments, the surface 312a of optical block 300 forms the surface 412a of optical block 400.

[0076] The embodiments described so far relate to the use of three optical blocks to form a composite optical block 400. However, in certain embodiments, optical block 300 may be omitted or replaced by one or more optical blocks bearing facets 38 in different orientations. Thus, optical block 400 can generally be considered to be formed from two optical subblocks having two regions, with optical block 200 having facet 28 forming the first subblock (first region) of the subblock, and optical block 100 having facet 18 forming the second subblock (second region) of the subblock. In embodiments illustrated in the drawings, the second subblock includes two subsubblocks (two subregions), with facet 18 located in the first subsubblock (first subregion), which in this case is optical block 100, and facet 38 located in the second subsubblock (second subregion), which in this case is optical block 300.

[0077] In embodiments in which optical block 300 is omitted, optical blocks 100 and 200 are joined together to form optical block 400 such that face 112b is connected to face 212a. As a result of joining (and proper alignment) of optical blocks 100 and 200, facet 18 is non-parallel to facet 28.

[0078] Referring to Figures 1A to 7B in succession, and now to Figures 8A to 9B, Figures 8A to 9B illustrate the steps for cutting the optical block 400 (Figures 8A and 8B) and the results of cutting the optical block 400 (Figures 9A and 9B). Generally, as shown in Figures 8A and 8B, the optical block 400 is cut along a cutting plane 402 that passes through 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 interchangeable) and at least one of faces 116a, 216a, and 316a. In embodiments where faces 116a, 216a, and 316a are coplanar and form face 416a, the cutting plane 402 passes through 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 subblock having facet 18 or facet 38. In the illustrated embodiment, the cross section 402 passes through a portion of the optical subblock having facet 18, which in the illustrated embodiment is the optical block 100. However, in some practical implementations, the cross section 402 may pass through all three regions of the optical block 400 (i.e., the regions including facets 18, 38, and 28 in combination).

[0079] In certain embodiments, the cutting plane 402 is oblique to a surface 412a (112a or 312a), and may also be oblique to one or more of the surfaces 116a, 316a, 412b, 112b, 312a, 312b, and 212a, depending on the structure of the optical block 400. Preferably, the cutting plane 402 is perpendicular to a surface 114a (and therefore, in embodiments where surfaces 114a, 314a, and 214a are parallel, it is also perpendicular to surfaces 314a and 214a). Cutting the optical block 400 along the cutting plane 402 results in an array of optical structures 400' having interface surfaces 404 (or "surfaces" 404) at the location of the cutting plane 402, as illustrated in Figures 9A and 9B.

[0080] As illustrated in Figures 7A to 7C, in some embodiments where the optical block 400 includes three optical blocks 100, 200, and 300, the position of the cutting surface 402 can be restricted so that the cutting surface 402 passes through only a portion of optical block 100 and not through any of the other optical blocks 200 and 300, and the portion to be cut is only a portion of optical block 100. However, in other embodiments, the position of the cutting surface 402 may be such that the cutting surface 402 passes through a portion of optical block 300, or a portion of optical block 200.

[0081] In embodiments where surfaces 116a, 216a, and 316a are coplanar and join to form surface 416a, the portion of optical block 400 that is cut off (i.e., removed) is a triangular prism (usually a right-angled triangular prism) portion (represented by 401 in Figures 8A and 8B). In embodiments where optical block 300 is sandwiched between optical block 100 and optical block 200, portion 401 includes a portion (typically the whole) of surface 116a and a portion (a minority portion, e.g., about 10% to 20%) of surface 112a.

[0082] In some embodiments in which the positions of optical blocks 100 and 300 are swapped so that optical block 100 is sandwiched between optical blocks 300 and 200, the position of the cutting surface can be restricted so that the cutting surface 402 passes through only a portion of optical block 300 and not through any of the other optical blocks 100 or 200, and the portion that is cut is only a portion of optical block 300. However, as described above, in certain embodiments, the cutting surface 402 may pass through a portion of optical block 100 and may also pass through a portion of optical block 200.

[0083] Figures 9A and 9B illustrate an optical structure 400' having an interface surface 404, which is formed as a result of cutting the optical block 400 along the cut surface 402 and removing the triangular prime portion 401. The optical block 500 having a coupled reflector is joined to the optical structure 400' at the interface surface 404.

[0084] The following paragraphs describe the structure and production of the optical block 500 with reference to Figures 10A to 10D. Referring first to Figures 10A to 10C, the optical block 500 is formed from a transparent material and has a pair of reflective inner surfaces 42 (high-reflectivity mirrors), each of which is used as a bonding configuration for the final composite LOE. The optical block 500 includes three pairs of faces (main outer surfaces), namely, preferably a pair of parallel faces 512a, 512b, a pair of faces 514a, 514b (which may or may not be parallel), and a pair of faces 516a, 516b (which may or may not be parallel). In certain embodiments, the three pairs of faces of the optical block 500 are orthogonal (perpendicular) to each other, but other embodiments in which the pairs of faces are not orthogonal to each other may be preferred.

[0085] The optical block 500 is formed from a plurality of bonded transparent coated plates 502 (each plate is formed from a transparent material and coated with a partially reflective coating) to form a reflective inner surface 42 that is obliquely inclined at a predetermined angle to either or both of the surfaces 512a, 512b. Various known methods exist for forming the optical block 500. Figure 10D illustrates one such method, in which the coated plates 502 are stacked and bonded (as in Figures 3C, 4C, and 5C), and then cut along equally spaced parallel cutting surfaces 504 (parallel to the yz plane in an arbitrarily labeled xyz coordinate system) to produce cut-out optical structures 505. One of the optical structures 505 is used to form the optical block 500. Unlike the coatings used to generate facets 18, 28, and 38, the coating used to form the coated plate 502 is not partially reflective, but rather fully (preferably highly) reflective, so that the resulting inner surface 42 functions as a totally reflective mirror. Dielectric coatings are an example of a suitable coating that can be used to form the reflective inner surface 42. The cross-section 504 is angled obliquely with respect to the coated surface of the plate 502, where the oblique angle of surface 504 determines the oblique angle to which the inner surface 42 is inclined with respect to surfaces 512a and 512b.

[0086] In certain embodiments, each of the optical structures 505 may be cut along two additional parallel planes 506, 508 perpendicular to the plane 504 to form surfaces 514a, 514b such that the optical block 500 has a rectangular cross-section. In an arbitrarily labeled xyz coordinate system, the planes 506, 508 are parallel to the xy plane.

[0087] Continuing to refer to Figures 8A to 10D, and also paying attention to Figures 11A and 11B, we see the optical block 500 and optical structure 400' before they are joined together to form the optical structure 600 (Figures 12A and 12B). Before joining, it is important that the optical block 500 and optical structure 400' are properly aligned such that the orientation of the inner surfaces 42 is non-parallel to the orientation of the facets 18, 28, and 38 (i.e., the inner surfaces 42 are non-parallel to the facets 18, 28, and 38), and that each inner surface 42 is associated with one of the LOE 20 in the optical block 200, and that the projection of the inner surface in the thickness dimension of each LOE (which is the yz plane in the xyz coordinate system arbitrarily labeled in the drawing) is bounded by the main surfaces 24a and 24b of the LOE 20.

[0088] In certain embodiments, it may also be preferable that each of surfaces 514a and 414a lies in a plane parallel to the xy-plane, and each of surfaces 514b and 414b lies in a plane parallel to the xy-plane.

[0089] To avoid waste in the final cutting step for cutting out the composite LOE, the optical block 500 preferably has the same thickness as the constituent optical blocks 100, 200, 300 (measured along the z-axis, i.e., between face 514a and face 514b), and therefore the same thickness as the optical structure 400'. In such embodiments, the alignment of the optical block 500 and the optical structure 400' is preferably such that faces 514a, 414a are coplanar, as are faces 514b, 414b. In such embodiments, the alignment of the optical block 500 and the optical structure 400' is also such that faces 512b, 404 are aligned and substantially coincide.

[0090] Once properly aligned, the optical block 500 and the optical structure 400' are joined together to form the optical structure 600 (an intermediate working product of the composite LOE fabrication process), as illustrated in Figures 12A and 12B. Joining the optical block 500 and the optical structure 400' is done so that the surface 512b is connected to the surface (interface surface) 404 while maintaining the above alignment. Preferably, the surfaces 512b, 404 are of equal dimensions or very close to equal dimensions. In certain embodiments, the alignment of the optical block 500 and the optical structure 400' may also include twisting or rotating the surface 512b relative to the interface surface 404, in addition to tilting it relative to either or both of the surfaces 512a, 512b, such that the inner surface 42 is tilted at an angle relative to the optical structure 400'. In the drawings, such tilt angles and inclination angles correspond to the inner surface 42 being tilted at two angles with respect to the xy plane.

[0091] As illustrated in Figure 13, after forming the optical structure 600, the optical structure 600 is cut (cut out) along two or more preferably parallel cutting surfaces 602 at predetermined intervals in order to extract one or more composite LOEs. The cutting surfaces 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 surfaces 602 are located between the continuous surfaces 24a and 24b of the LOE 20, and in particular, in the bonding region formed between the continuous surfaces 24a and 24b of the LOE 20. For example, the first cutting surface 602-1 of the cutting surfaces 602 passes through the joint region between the second surface 24b-1 of the first LOE20-1 of LOE20 and the first surface 24a-2 of the second LOE20-2 of LOE20 which is adjacent to the first LOE20-1 and joined to the first LOE20-1. The second cutting surface 602-2 of the cutting surfaces 602 adjacent to the first cutting surface 602-1 passes through the joint region between the second surface 24b-2 of the second LOE20-2 and the third LOE20-3 of LOE20 which is adjacent to the second LOE20-2 and joined to the second LOE20-2. It should be noted that the joint region (formed between consecutive surfaces 24a, 24b of LOE20) can provide a guide for the placement of the cutting surfaces 602. It should be further noted that the slight deviation from the parallelism of the cutting planes, resulting in two main planes formed by cutting along the continuous cutting planes 602 of the nearly parallel but not perfectly parallel cut composite LOE, can be corrected by grinding the composite LOE along the two main planes.

[0092] Referring further to Figures 14A to 14C, a composite LOE 700 is shown, which is cut out from the optical structure 600 after cutting along the cutting plane 602. The composite LOE 700 includes a first pair of faces 712a, 712b (including portions of faces 412a, 412b, which may or may not be parallel faces), a second pair of parallel faces 714a, 714b (principal faces) (preferably partially formed by one of the faces 24a, 24b of LOE 20) formed by cutting the optical structure 600 along the continuous cutting plane 602, and a third pair of faces 716a, 716b (including portions of faces 416a, 416b, which may or may not be parallel faces). Most notably, the composite LOE 700 has a first plurality of facets 18 having a first orientation (within the first LOE region 710) and which may be inclined obliquely with respect to surfaces 714a, 714b or perpendicular to surfaces 714a, 714b; a second plurality of facets 28 having an orientation obliquely with respect to surfaces 714a, 714b (within the second LOE region 720) and which is non-parallel to the orientation of facets 18; and at least one facet 38 located within the region 730 between the first LOE region and the second LOE region, which is parallel to surfaces 714a, 714b and non-parallel to the orientation of facets 18, 28. The composite LOE700 also includes a (high) reflective inner surface 42 (also referred to as a coupled reflector) located within a coupled region 750 bounded by surfaces 512a, 514a', 514b', 516a, and 516b, which has an orientation nonparallel to the orientation of facets 18, 28, and 38 (i.e., the reflective inner surface 42 is nonparallel to facets 18, 28, and 38). Surfaces 514a' and 514b' are parallel to each other and form part of surfaces 714a and 714b. In embodiments in which the surface 512b of optical block 500 (or the surface 512b' of block 500', or the surface 582 of block 580 / 590) is twisted or rotated relative to the interface surface 404, the reflective surface 42 is tilted about two axes with respect to the waveguide axis (these may be tilt angles measured with respect to the x and y axes in an xyz coordinate system arbitrarily labeled in the drawings).

[0093] As should be clear, unlike the composite LOE illustrated in Figures 1A to 2B, the composite LOE 700 does not have a rectangular cross-section in a two-dimensional plane (it is almost evident in the xy plane shown in Figure 14B) due to the cutting and joining steps described above with reference to Figures 8A to 12B.

[0094] After cutting out the composite LOE 700, each of the composite LOEs can be polished on its outer surfaces 714a and 714b to form a final composite LOE having a desired thickness (measured along the z-axis of an xyz coordinate system arbitrarily labeled in the drawing) and to ensure parallelism between surfaces 714a and 714b and (an optional facet 38). Figure 15 shows one example of the resulting polished composite LOE having parallel surfaces 714a' and 714b' corresponding to the polished surfaces 714a and 714b.

[0095] The composite LOE produced using the fabrication process according to the embodiments disclosed herein offers several advantages over composite LOEs produced using conventional fabrication methods. Firstly, the position of the cross-section 402 in a designated region of the optical block 400 (Figures 8A and 8B) corresponds to the placement of the coupled reflector 42 in a region that presents a more aesthetically pleasing overall design of the composite LOE 700. In addition, the spatial positioning of the coupled reflector 42, determined by the bevel angles of the cross-section 402 and the cross-section 504 (Figure 10D), determines the spatial orientation of the image projector that produces the collimated image light. In the disclosed embodiments, the spatial orientation of the coupled reflector 42 can be designed to correspond to the spatial positioning of the image projector below the composite LOE in relation to a portion of the coupling region 750 or a nearby surface 714b', thereby providing an aesthetically pleasing placement of the image projector and reducing the overall form factor of the optical system formed from the composite LOE and image projector, which can be implemented in certain non-limiting implementations as part of a head-mounted display and as part of an eyeglasses form factor. Furthermore, the reduction in raw material waste and the fact that numerous composite LOEs can be cut from a single optical structure 600, as made possible by the disclosed fabrication process, facilitate the large-scale production of composite LOEs while maintaining lower manufacturing costs compared to conventional fabrication methods used to produce composite LOEs.

[0096] As described above, the composite LOE according to the disclosed embodiment can be attached to or otherwise coupled to an image projector that produces collimated image light which can be coupled to the composite LOE by the reflective inner surface 42. In a preferred embodiment, the coupling reflector is designed to correspond to the spatial positioning of the image projector below the composite LOE. For both functional and aesthetic reasons, it is typically desirable that the collimated image ray corresponding to the central field principal ray produces an angle (up to about 20°) that is substantially perpendicular to the composite LOE, both 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 facet 28). Therefore, it is preferable that the reflective inner surface 42 and facet 28 have similar elevation angles. In other words, the angle of the reflective inner surface 42 measured relative to surfaces 512a and 512b is often approximately equal to the angle of the facet 28 measured relative to surfaces 714a' and 714b' (or similarly measured relative to surfaces 24a and 24b of the component LOE 20 that forms the composite LOE).

[0097] In many cases, only a portion of the reflective inner surface 42 provides a useful active area for coupling light from the image projector to the composite LOE, while the rest of the reflective inner surface 42 either does not couple any light to the composite LOE or couples light at an angle that results in undesirable reflections on the main surface of the composite LOE, causing ghost images. In addition, the reflective coating used to form the coated plate 502 (Figure 10D) for producing the reflective inner surface 42 is typically expensive, and therefore, reducing any unused (i.e., "inactive") area of ​​the inner surface 42 can reduce manufacturing costs. Thus, to reduce manufacturing costs by preventing or reducing undesirable reflections and to mitigate ghost images, it may be advantageous to limit the size of the reflective inner surface 42 to the active area and fill the remaining area with a less expensive inert material (such as glass, plastic, or metal).

[0098] Referring further to Figures 16A to 18B, the following paragraph describes embodiments in which a reduced-size reflective inner surface 42 is produced from a reduced-size optical block 500', which is bonded together with one or more blocks 800, 900 of inert material such as glass, plastic, or metal. The materials used to form the blocks 800, 900 (synonymous herein with “inert blocks”) may be the same or different. For example, both blocks 800, 900 may be formed from glass, or one of the blocks may be formed from glass and the other from plastic. The optical block 500' is structurally similar to the optical block 500 in that the length of the optical block 500' (measured along the y-axis in an xyz coordinate system arbitrarily labeled in the drawings) is reduced compared to the length of the optical block 500, thereby limiting the size of the inner surface 42 to only a useful active area. Due to the structural similarity between optical block 500' and 500, similar reference numbers are used to identify similar components, and the reference number for optical block 500' is preceded by an apostrophe ('').

[0099] The inert block 800 has three pairs of faces (main 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), and a third pair of faces 816a, 816b (which may or may not be parallel). The optical block 500' is size-constrained by the inert block 800, and therefore the inert block 800 can be understood to function as a ghost reduction element, which restricts the size of the inner surface 42 to only the useful active area. In a particular embodiment, the block 800 is a rectangular cube.

[0100] The inert block 900 also has three pairs of parallel faces (main outer faces), namely, a first pair of preferably parallel faces 912a, 912b, a second pair of faces 914a, 914b (which may or may not be parallel), and a third pair of faces 916a, 916b (which may or may not be parallel). In certain embodiments, the block 900 is a rectangular cube. As will be considered, the block 900 is optional but may be advantageously used to provide structural reinforcement and support to the optical block 500'.

[0101] The joining is preferably carried out at the stage in which optical block 500' and block 800 are first joined together to form composite block 580. Blocks 500' and 800 are properly aligned before being joined together. Referring to the coordinate system shown in Figures 16A and 16B, the alignment of blocks 500' and 800 (if each of blocks 500' and 800 is configured as a rectangular cube) can be understood as follows: faces 512a' and 812a are in a plane parallel to the yz plane and preferably coplanar; faces 512b' and 812b are in a plane parallel to the yz plane and preferably coplanar; faces 514a' and 814a are in a plane parallel to the xy plane and preferably coplanar; faces 514b' and 814b are in a plane parallel to the xy plane and preferably coplanar; and faces 516b' and 816a are aligned and coincide in a plane parallel to the xz plane.

[0102] Blocks 500' and 800 are joined together to form a composite block 580, such that face 516b' is connected to face 816a, while maintaining the alignment described with reference to Figures 16A and 16B. Block 580, shown in Figures 17A and 17B, has a first pair of preferably parallel faces 582a, 582b formed from faces 512a', 812a and 512b', 812b, respectively; faces 584a, 584b (which may or may not be parallel) formed from a second pair of faces 514a', 814a and 514b', 814b, respectively; and a third pair of faces 516a', 816b (which may or may not be parallel). The inner surface 42 is located in the first region of block 580 and is inclined obliquely with respect to faces 582a, 582b.

[0103] In certain embodiments, blocks 580 and 900 can then be joined together to form a composite block 590, as illustrated in Figures 18A and 18B. Blocks 580 and 900 are properly aligned before being joined together. Referring to the coordinate systems shown in Figures 17A and 17B, the alignment of blocks 580' and 900 (when each of blocks 580' and 900 is constructed as a rectangular cube) can be understood as follows: faces 516a' and 916a lie in a plane parallel to the xz plane and are preferably coplanar; faces 516b' and 916b lie in a plane parallel to the xz plane and are preferably coplanar; faces 584a' and 914a lie in a plane parallel to the xy plane and are preferably coplanar; faces 584b' and 914b lie in a plane parallel to the xy plane and are preferably coplanar; and faces 582a and 912b are aligned and coincide in a plane parallel to the yz plane.

[0104] Blocks 580' and 900 are joined together to form a composite block 590, such that face 912b' is connected to face 582a, while maintaining the alignment described with reference to Figures 17A and 17B. Block 590, shown in Figures 18A and 18B, has a first pair of parallel faces 912a, 582b, a second pair of faces 594a, 594b (which may or may not be parallel) formed from faces 914a, 584a and 914b, 584b, and a third pair of faces 596a, 596b (which may or may not be parallel) formed from faces 916a, 586a and 916b, 586b, respectively.

[0105] Next, block 590 can be aligned with and joined together with the optical structure 400' instead of optical block 500, as described with reference to Figures 11A to 12B. When block 590 is used instead of block 500, joining block 590 together with the optical structure 400' results in face 582b being connected to interface face 404, as shown in Figures 19A and 19B. As a result, only a portion of interface face 404 is connected to face 512b' (which forms part of face 582b). This is in contrast to the embodiments illustrated in Figures 12A and 12B, where the entire face 512b is connected to the entire interface face 404. The optical structure formed as a result of joining block 590 and optical structure 400' together can then be cut out at predetermined intervals separated by parallel cutting planes to extract one or more composite LOEs, as described with reference to Figure 13.

[0106] In certain embodiments, the inert block 900 can be joined to the optical block 500 without the inert block 800 to provide structural reinforcement and support. For example, in one embodiment, the inert block 900 and the optical block 500 are joined together to form an intermediate block such that face 912b connects to face 512a of the optical block 500. In such embodiments, the inert block 900 and the optical block 500 are properly aligned before being joined together.

[0107] In another similar embodiment, the inert block 900 and the optical block 500' are joined together without the presence block 800. In such an embodiment, joining is performed such that face 912b is connected to 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 together. Optionally, the size of the inert block 900 can be reduced to match the size of the optical block 500'.

[0108] In certain embodiments, it may be advantageous to provide a transparent cover plate on either or both of the polished surfaces 714a', 714b' of a cut composite LOE, such as the composite LOE illustrated in Figure 15. In certain embodiments, such a transparent cover plate may be provided directly on the surfaces 714a', 714b' (i.e., after the cut composite LOE has been polished).

[0109] In other embodiments, transparent cover plates can be provided as spacer plates between LOE 20s during the generation of the optical block 200, as shown in Figures 20A and 20B. Looking at Figure 20A first, an aligned arrangement 220 of the LOE 20s and transparent cover plates 220s is illustrated, where the LOE 20s and cover plates 230s are arranged alternately along the length of the arrangement 220 perpendicular to the parallel surfaces 24a, 24b of the LOE 20s (where the length is along the z-axis). Each cover plate 230 has a pair of parallel outer surfaces 231a, 231b. The cover plates 230s and LOE 20s are joined together, as shown in Figure 20B, to form a joined stack 200' (also referred to as the optical block 200'). The joining is done so that the surfaces 231b, 24a of adjacent cover plates 230s are connected to the LOE 20s, and the surfaces 231a, 24b of adjacent cover plates 230s are connected to the LOE 20s.

[0110] Stack 200' is generally similar in structure to Stack 200 in Figure 3A (i.e., Stack 200' has three pairs of parallel faces and is formed from multiple joined LOEs), and similar reference numerals are used to indicate similar elements. One notable difference between Stack 200 and 200' is that Stack 200' is a joined stack of LOE 20 and cover plates 230, in which the LOE 20 and cover plates 230 are arranged alternately along the length of Stack 200' perpendicular to faces 214a, 214b (and parallel to faces 212a, 212b). These transparent cover plates 230 are also referred to as transparent spacer plates because they provide spacing between consecutive LOEs.

[0111] In embodiments providing an optical block 200' having an LOE 20 with a spacer plate 230 in between, the thickness of the coated plate 302 used in forming the optical block 300 should be adjusted considering the overall thickness of the optical block 200', such that each facet 38 is located in a plane midway between the main faces 24a and 24b of the associated LOE 20, so that as a result of the alignment of the optical blocks 200', 300, the optical blocks 200', 300 are joined together in proper alignment. In addition, when performing the cutting step to cut out the composite LOE when using optical block 200' instead of optical block 200, the continuous cutting planes pass through a continuous spacer plate 230 having one of the LOE 20 between them, as illustrated in Figure 21, preferably passing approximately through the center of the spacer plate 230.

[0112] Figure 22 illustrates an example of a cut composite LOE 700 having two transparent cover plates 232 and 234. Cover plates 232 and 234 are formed from two of the cover plates 230 in a stack 200' cut along two of the cut surfaces 602. Cover plates 232 and 234 are joined to the LOE 20 such that the surface 231b of cover plate 232 is connected to the surface 24a of the LOE 20, and the surface 231a of cover plate 234 is connected to the surface 24b of the LOE 20. The surface 233a of cover plate 232 (the surface opposite to the surface 231b of cover plate 232) and the surface 233b of cover plate 234 (the surface opposite to the surface 231a of cover plate 234) form parts of the main outer surfaces 714a and 714b of the composite LOE 700, respectively. Next, the surfaces 714a and 714b of the composite LOE in Figure 22 can be polished in the same manner as described above with reference to Figure 15, thereby achieving a final composite LOE with the desired thickness and ensuring parallelism between surfaces 714a and 714b.

[0113] The embodiments described herein relate to bonding an optical block 500 (or 500') to an optical structure 400' such that the coupled reflector 42 corresponds to the spatial positioning of the image projector below the final composite LOE product; however, other embodiments are possible to correspond to different spatial positionings of the image projector. For example, the optical block 500 can be inverted (for example, by swapping the positions of surfaces 514a and 514b) such that the inner surface 42 is tilted upward rather than downward, as shown in Figures 10A, 10B, 11A, and 12A. Such a configuration allows the image projector to be deployed above the final composite LOE product.

[0114] Although not illustrated in the drawings, additional optical components, such as prisms, may be optically coupled or joined to the optical block 500 (or 500') with or without the inert block 800 and / or 900 before cutting out the composite LOE, in order to provide additional combined geometry of the final composite LOE product. Alternatively, one or more additional optical components, such as prisms, may be optically coupled or joined to the coupling reflector 42 in the coupling region 750.

[0115] This disclosure describes various cutting steps in which optical materials are cut along a cutting plane to produce various optical blocks and subcomponents of optical blocks. It should be noted that in certain embodiments, some or all of the surfaces resulting from these cutting steps can be polished before the joining process. For example, the joined surfaces of optical blocks 100, 200, and 300 can be polished before joining the optical blocks 100, 200, and 300 together. In addition, the main surface of the LOE used to form optical block 200 can be polished before forming the joined stack of LOE (optical block 200). Furthermore, the interface surface 404 and the joining surface of optical block 500 can be polished before joining the optical blocks 400 and 500 together.

[0116] The alignment of the various blocks and structures described herein can be performed using any suitable optical alignment apparatus / device / tool ​​that performs a suitable optical alignment technique / method. Such suitable optical alignment apparatus / device / 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 photodetectors / sensors, one or more optical components (e.g., one or more lenses, foldable optical components, etc.), an autocollimator, and the like. Details of non-limiting examples of suitable optical alignment apparatus / device / tool / methods that can be used to align the various blocks and structures described herein can be found in various publications by Lumus Ltd. (Israel), including, for example, International Patent Application No. PCT / IL2021 / 051377 and International Patent Application No. PCT / IL2021 / 051378, which were not published as of the filing date of this application and do not constitute prior art.

[0117] Cutting or shaping of optical blocks and optical structures described herein can be performed by any suitable cutting apparatus / device / tool, as should be understood by those skilled in the art. Polishing of faces and surfaces of optical blocks and optical structures (including composite LOEs) described herein can be performed by any suitable polishing apparatus / device / tool, as should be understood by those skilled in the art.

[0118] The embodiments described herein relate to joining together two or three optical blocks, each bearing two or three sets of facets in a predetermined orientation, to accommodate the deflection of light in a predetermined direction. However, other embodiments are contemplated herein in which one or more additional optical blocks, each bearing one or more additional sets of facets or optical retarders (such as one or more waveplates) in a predetermined orientation, 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.

[0119] The descriptions of the various embodiments of this disclosure have been presented for illustrative purposes only and are not intended to be exhaustive or limitful to the embodiments disclosed. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the embodiments described. The terms used herein have been selected to best describe the principles of the embodiments, their practical applications or technical improvements to the art available on the market, or to enable those skilled in the art to understand the embodiments disclosed herein.

[0120] As used herein, the singular forms "a," "an," and "the" include plural references unless the context clearly indicates otherwise.

[0121] The term “exemplary” is used herein to mean “serving as an example, illustration, or representation.” Any embodiment described as “exemplary” should not necessarily be construed as being preferable or advantageous to other embodiments, and / or preclude the incorporation of features from other embodiments.

[0122] For clarity, it is understood that certain features of the Invention described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, for brevity, various features of the Invention described in the context of a single embodiment may also be provided separately, in any preferred partial combination, or as suitable for any other described embodiment of the Invention. Certain features described in the context of different embodiments should not be considered essential features of those embodiments unless the embodiments would not function without those elements.

[0123] To the extent that the attached claims are drafted without multiple dependencies, this is done solely to comply with the formal requirements of jurisdictions that do not permit such multiple dependencies. It should be noted that all possible combinations of features that would be implied by making the claims multiple dependencies are explicitly assumed and should be considered part of the invention.

[0124] While the present invention has been described in conjunction with its specific embodiments, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. Therefore, the appended claims are intended to encompass all such alternatives, modifications, and variations that fall within the spirit and broad scope of the invention.

Claims

1. A method for fabricating a composite optical element (LOE), To obtain a stack (200) having a first pair of faces (212a, 212b) and a plurality of LOEs (20), wherein each of the LOEs (20) has a pair of principal parallel faces (24a, 24b) and a first plurality of mutually parallel partially reflective inner surfaces (28) oblique to the pair of principal parallel faces (24a, 24b), To obtain a first optical block (100, 300) having a second pair of surfaces (112a, 112b, 312a, 312b) and a second plurality of mutually parallel partially reflective inner surfaces (18, 38), One of the surfaces (212a) of the first pair of surfaces is connected to one of the surfaces (112b, 312b) of the second pair of surfaces, and the first optical block (100, 300) and the stack (200) are joined together such that the first plurality of partially reflective inner surfaces (28) are non-parallel to the second plurality of partially reflective inner surfaces (18, 38), thereby forming the second optical block (400). The second optical block (400) is cut along a cutting surface (402) passing through the other of the two faces (112a, 312a) of the second pair of faces, thereby forming a first optical structure (400') having an interface surface (404) at the cutting surface (402), To obtain a third optical block (500) having a third pair of surfaces (512a, 512b, 512a', 512b') and a plurality of mutually parallel reflective inner surfaces (42), The third optical block (500) and the first optical structure (400') are joined together such that one of the surfaces (512b, 512b') of the third pair of surfaces is connected to the interface surface (404), and the plurality of reflective inner surfaces (42) are non-parallel to both the first plurality of partial reflective inner surfaces (28) and the second plurality of partial reflective inner surfaces (18, 38), thereby forming the second optical structure (600'). A method comprising cutting the second optical structure (600) through at least two cutting planes (602) that are substantially parallel to the principal parallel planes (24a, 24b) of a continuous LOE (20) to cut out at least one composite LOE (700) from the second optical structure (600).

2. The method according to claim 1, further comprising polishing the outer surfaces (714a, 714b) of the cut composite LOE (700) formed by cutting the optical structure (600) along two consecutive of the cut surfaces (602) for each cut composite LOE.

3. The method according to claim 1, wherein the first optical block (100) has a pair of parallel surfaces (114a, 114b), and the second plurality of partially reflective inner surfaces (18) are perpendicular to the pair of parallel surfaces (114a, 114b) of the first optical block (100).

4. The method according to claim 1, wherein the first optical block (100) has a pair of parallel surfaces (114a, 114b), and the second plurality of partially reflective inner surfaces (18) are oblique to the pair of parallel surfaces (114a, 114b) of the first optical block (100).

5. The method according to claim 1, wherein the first optical block (100, 300) has a third plurality of mutually parallel partial reflective inner surfaces (38) that are non-parallel to the first plurality of partial reflective inner surfaces (28) and the second plurality of partial reflective inner surfaces (18).

6. The method according to claim 5, wherein the first optical block (100, 300) has a first region (100) including a second plurality of partially reflective inner surfaces (18) and a second region (300) including a third plurality of partially reflective inner surfaces (38), and the first and second regions (100, 300) of the first optical block (100, 300) are non-overlapping regions.

7. The method according to claim 5, wherein the third plurality of partially reflective inner surfaces (38) are parallel to the principal parallel surfaces (24a, 24b) of the LOE (20).

8. The method according to claim 5, wherein each of the third partially reflective inner surfaces (38) is located in a plane substantially midway between each of the pair of principal parallel surfaces (24a) and principal parallel surfaces (24b) of the LOE (20).

9. The method according to claim 5, wherein the third plurality of partially reflective inner surfaces (38) are located between the first plurality of partially reflective inner surfaces (28) and the second plurality of partially reflective inner surfaces (18).

10. The method according to claim 5, wherein the second plurality of partially reflective inner surfaces (18) are located between the first plurality of partially reflective inner surfaces (28) and the third plurality of partially reflective inner surfaces (38).

11. First and second constituent optical blocks (100, 300), each having a pair of faces (112a, 112b, 312a, 312b), are assembled together such that the first optical block (100, 300) is connected to one of the faces (112b, 312b) of the pair of faces of the first constituent optical block (100, 300) and to one of the faces (312a, 112a) of the pair of faces of the second constituent optical block (300, 100). The method according to claim 1, wherein the first constituent optical block (100, 300) is formed by joining, and the first constituent optical block (100, 300) includes the second plurality of partially reflective inner surfaces (18, 38), and the second constituent optical block (300, 100) includes a third plurality of mutually parallel partially reflective inner surfaces (38, 18) that are non-parallel to the first plurality of partially reflective inner surfaces (28) and non-parallel to the second plurality of partially reflective inner surfaces (18, 38).

12. The method according to claim 1, wherein the third optical block (500) and the first optical structure (400') are joined together such that substantially the entirety of one of the third pair of surfaces (512b) is connected to substantially the entirety of the interface surface (404).

13. The method according to claim 1, wherein the third optical block (500) and the first optical structure (400') are joined together such that one of the third pair of surfaces (512b') is connected to a portion of the interface surface (404).

14. The third optical block (500) has an additional pair of faces (516a', 516b'), and the method is To obtain an inert block (800) having a first and second pair of faces (816a, 816b, 812a, 812b), The inert block (800) and the third optical block (500) are joined together such that one of the first pair of faces (816b) of the inert block (800) is connected to one of the additional pair of faces (516a') of the third optical block (500), thereby forming a composite block (580) having first and second faces (582b, 582a), wherein the first face (58 The method according to claim 1, further comprising forming 2b) from one of the faces of the third pair of faces (512b') and one of the faces of the second pair of faces of the inert block (800) (812b), and the second pair of faces (582a) of the composite block (580) being formed from the other of the faces of the third pair of faces (512a') and one of the faces of the second pair of faces of the inert block (800) (812a).

15. The method according to claim 14, further comprising: obtaining a second inert block (900) having a pair of faces (912a, 912b); and joining the second inert block (900) and the composite block (580) together such that one of the faces (912b) of the pair of faces of the second inert block (900) is connected to the second face (582a) of the composite block (580).

16. The method according to claim 14, wherein joining the third optical block (500) and the first optical structure (400') together includes joining the composite block (580) and the first optical structure (400') together such that the first surface (582b) of the composite block (580) is connected to the interface surface (404).

17. To obtain an inert block (900) having a pair of faces (912a, 912b), The method according to claim 1, further comprising joining the inert block (900) and the third optical block (500, 500') together such that one of the pair of faces (912b) of the second inert block (900) is connected to the other of the third pair of faces (512a, 512a') of the optical block (500, 500').

18. A method for fabricating a composite optical element (LOE), The first optical block (400) is obtained, and the first optical block (400) is At least the first pair of faces (412a, 412b), A first region (200) formed from a stack (200) of LOE, wherein each of the LOE (20) has a pair of principal parallel surfaces (24a, 24b) and a set of mutually parallel partial reflective inner surfaces (28) located between the parallel surfaces (24a) and the parallel surfaces (24b) and inclined obliquely with respect to the parallel surfaces (24a, 24b) such that the first region (200) includes a first plurality of partial reflective inner surfaces (28), A second region (100, 300) having a second plurality of mutually parallel partial reflective inner surfaces (18, 38) that are non-parallel to the first plurality of partial reflective inner surfaces (28), to be obtained, The first optical block (400) is cut along a cutting surface (402) passing through one of the first pair of faces (412a), thereby forming a first optical structure (400') having an interface surface (404) at the cutting surface (402), To obtain a second optical block (500) having a second pair of surfaces (512a, 512b, 512a', 512b') and a plurality of mutually parallel reflective inner surfaces (42), The first optical structure (400') and the second optical block (500) are joined together such that one of the surfaces (512b, 512b') of the second pair of surfaces is connected to the interface surface (404), and the plurality of reflective inner surfaces (42) are non-parallel to both the first plurality of partial reflective inner surfaces (28) and the second plurality of partial reflective inner surfaces (18, 38), thereby forming the second optical structure (600). A method comprising cutting the second optical structure (600) through at least two cutting planes (602) that are substantially parallel to the principal parallel planes (24a, 24b) of a continuous LOE (20) to cut out at least one composite LOE (700) from the second optical structure (600).

19. The method according to claim 18, wherein the first optical block (400) further includes an additional pair of faces (414a, 414b), and one of the principal parallel faces (24a) of the LOE (20) at the upper end of the stack (200) forms a portion of one of the faces (414a) of the additional pair of faces, and one of the principal parallel faces (24b) of the LOE (20) at the lower end of the stack (200) forms a portion of the other face (414b) of the additional pair of faces.

20. The method according to claim 18, wherein the second optical subblock (100, 300) includes a first subblock region (100, 300) and a second subblock region (300, 100), the second plurality of partially reflective inner surfaces (18, 38) are located within the first subblock region (100, 300), the third plurality of mutually parallel partially reflective inner surfaces (38, 18) are located within the second subblock region (300, 100), and the third plurality of partially reflective inner surfaces (38, 18) are non-parallel to the first plurality of partially reflective inner surfaces (28) and non-parallel to the second plurality of partially reflective inner surfaces (18, 38).

21. The method according to claim 20, wherein the third plurality of partially reflective inner surfaces (38) are located between the first plurality of partially reflective inner surfaces (28) and the second plurality of partially reflective inner surfaces (18).

22. The method according to claim 20, wherein the second plurality of partially reflective inner surfaces (18) are located between the first plurality of partially reflective inner surfaces (28) and the third plurality of partially reflective inner surfaces (38).

23. A method for fabricating a composite optical element (LOE), To obtain a first optical block (100) having a first pair of surfaces (112a, 112b) and a first plurality of mutually parallel partially reflective inner surfaces (18), Obtaining a second optical block (200) formed as a stack (200) of LOE (20) and having a second pair of faces (212a, 212b), wherein each of the LOE (20) has a pair of principal parallel faces (24a, 24b) and a second plurality of mutually parallel partially reflective inner surfaces (28) oblique to the pair of principal parallel faces (24a, 24b), To obtain a third optical block (300) having a third pair of surfaces (312a, 312b) and a third plurality of mutually parallel partially reflective inner surfaces (38), The first optical block (100) and the third optical block (300) are joined together, and the second optical block (200) and the third optical block (300) are joined together to form a fourth optical block (400), wherein the joining is i) One of the faces (112b) of the first pair of faces is connected to one of the faces (312a) of the third pair of faces, ii) One of the faces of the second pair of faces (212a) is connected to the other of the faces of the third pair of faces (312b), iii) The third plurality of partially reflective inner surfaces (38) are substantially parallel to the main parallel surfaces (24a, 24b) of the LOE (20), iv) The first, second, and third plurality of partially reflective inner surfaces (18, 28, 38) are formed such that they are non-parallel to each other. The fourth optical block (400) is cut along a cutting surface (402) passing through the other of the first pair of faces (112a), thereby forming a first optical structure (400') having an interface surface (400) at the cutting surface (402), To obtain a fifth optical block (500) having a fourth pair of surfaces (512a, 512b, 512a', 512b') and a plurality of mutually parallel reflective inner surfaces (42), The first optical structure (400') and the fifth optical block (500) are joined together to form a second optical structure (600), wherein the joining of the first optical structure (400') and the fifth optical block (500) is such that one of the surfaces (512b, 512b') of the fourth pair of surfaces is connected to the interface surface (404), and the plurality of reflective inner surfaces (42) are non-parallel to the first, second, and third plurality of partially reflective inner surfaces (18, 28, 38), and the formation is such that A method comprising cutting the second optical structure (600) through at least two cutting planes (602) that are substantially parallel to the principal parallel planes (24a, 24b) of a continuous LOE (20) to cut out at least one composite LOE (700) from the second optical structure (600).

24. A method for fabricating a composite optical element (LOE), To obtain a first optical block (100) having a first pair of surfaces (112a, 112b) and a first plurality of mutually parallel partially reflective inner surfaces (18), Obtaining a second optical block (200) formed as a stack (200) of LOE (20) and having a second pair of faces (212a, 212b), wherein each of the LOE (20) has a pair of principal parallel faces (24a, 24b) and a second plurality of mutually parallel partially reflective inner surfaces (28) oblique to the pair of principal parallel faces (24a, 24b), To obtain a third optical block (300) having a third pair of surfaces (312a, 312b) and a third plurality of mutually parallel partially reflective inner surfaces (38), The first optical block (100) and the third optical block (300) are joined together, and the first optical block (100) and the second optical block (200) are joined together to form a fourth optical block (400), wherein the joining is i) One of the faces of the third pair of faces (312b) is connected to one of the faces of the first pair of faces (112a), ii) One of the faces of the second pair of faces (212a) is connected to the other face of the first pair of faces (112b), iii) The third plurality of partially reflective inner surfaces (38) are substantially parallel to the main parallel surfaces (24a, 24b) of the LOE (20), iv) The first, second, and third plurality of partially reflective inner surfaces (18, 28, 38) are formed such that they are non-parallel to each other. The fourth optical block (400) is cut along a cutting surface (402) passing through the other of the three faces (312a) of the third pair of faces, thereby forming a first optical structure (400') having an interface surface (400) at the cutting surface (402), To obtain a fifth optical block (500) having a fourth pair of surfaces (512a, 512b, 512a', 512b') and a plurality of mutually parallel reflective inner surfaces (42), The first optical structure (400') and the fifth optical block (500) are joined together to form a second optical structure (600), wherein the joining of the first optical structure (400') and the fifth optical block (500) is such that one of the surfaces (512b, 512b') of the fourth pair of surfaces is connected to the interface surface (404), and the plurality of reflective inner surfaces (42) are non-parallel to the first, second, and third plurality of partially reflective inner surfaces (18, 28, 38), thereby forming the second optical structure (600). A method comprising cutting the second optical structure (600) through at least two cutting planes (602) that are substantially parallel to the principal parallel planes (24a, 24b) of a continuous LOE (20) to cut out at least one composite LOE (700) from the second optical structure (600).

25. The method according to any one of the prior claims, wherein the stack (200) is a bonding stack of the LOE (20) and a plurality of transparent spacer plates (230), and the LOE (20) and the transparent spacer plates (230) are alternately arranged along the length of the stack (200) perpendicular to the main parallel planes (24a, 24b) of the LOE (20).

26. The method according to claim 25, wherein the at least two cut surfaces (602) are located on a continuous spacer plate (230) having one of the LOE (20) between the at least two cut surfaces (602).

Images