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

Abstract

The stack has a first face and a second face, as well as multiple layers of glass (LOEs). Each LOE has two parallel main surfaces and a first plurality of parallel internal facets inclined relative to the main surfaces. A first block has a third and a fourth face, as well as a second plurality of parallel internal facets. The first block and the stack are joined such that the second face connects to the third face, and the first and second facets are not parallel, thus forming a second block. The second block is cut with a plane passing through the first face, thus forming a first structure with mating surfaces. A third block has a fifth and a sixth face, as well as a plurality of parallel internal reflectors. The third block and the first structure are joined such that the fifth face connects to the mating surfaces, and the internal reflectors are not parallel to all the facets, thus forming a second structure. A composite LOE is cut from the second structure.

Description

Technical Field

[0001] This invention relates to light-guide optical elements (LOEs), and more particularly to a method for manufacturing composite LOEs with embedded coupled reflectors for two-dimensional aperture expansion.

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

[0003] Composite LOEs, or “two-dimensional extended waveguides,” have been described in various publications of Lumus Ltd (Israel). Generally, these composite LOEs employ two regions, each a parallel facet block of a transparent material (i.e., a light-transmitting material) used to facilitate the propagation of light corresponding to the collimated image through internal reflection at the main surface. Each of the two regions includes a set of mutually parallel, internal, partially reflective surfaces (or “facets”) that redirect the collimated image light while simultaneously expanding the optical aperture. By combining two such elements with different facet orientations, two-dimensional expansion of the optical aperture can be achieved within a single composite element, thereby expanding the input image from an image projector and outputting the expanded image over a large area toward the observer's eye. Summary of the Invention

[0004] Embodiments of the present invention provide a method for manufacturing composite LOE. According to the teachings of embodiments of the present invention, a method for manufacturing a composite light guide optical element (LOE) is provided. The method includes: obtaining a stack having a first opposite face and a plurality of LOEs, each of the LOEs having a pair of principal parallel surfaces and a first plurality of mutually parallel partially reflective inner surfaces inclined relative to the pair of principal parallel surfaces; obtaining a first optical block having a second opposite face and a second plurality of mutually parallel partially reflective inner surfaces; joining the first optical block and the stack such that one face of the first opposite face is connected to one face of the second opposite face, and such that the first plurality of partially reflective inner surfaces are not parallel to the second plurality of partially reflective inner surfaces, thereby forming a second optical block; and cutting along a cutting plane passing through another face of the second opposite face. A second optical block is formed, thereby creating a first optical structure having a mating surface at the cutting plane; a third optical block is obtained, having a third opposite face and a plurality of mutually parallel reflective inner surfaces; the third optical block and the first optical structure are joined together such that one face of the third opposite face is connected to the mating surface, and such that the plurality of reflective inner surfaces are not parallel to both the first plurality of partial reflective inner surfaces and the second plurality of partial reflective inner surfaces, thereby forming a second optical structure; and at least one composite LOE is cut from the second optical structure by cutting the second optical structure via at least two cutting planes substantially parallel to the main parallel surfaces of the continuous LOE.

[0005] Optionally, the method further includes polishing the outer surface of each cut composite LOE formed by cutting the optical structure along two consecutive cutting planes in the cutting plane. 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. Optionally, the first optical block has a pair of parallel surfaces, and the second plurality of partially reflective inner surfaces are inclined relative to the pair of parallel surfaces of the first optical block.

[0006] Optionally, the first optical block has a third plurality of mutually parallel partially reflective inner surfaces that are not parallel to the first plurality of partially reflective inner surfaces and the second plurality of partially reflective inner surfaces. Optionally, the first optical block has a first region and a second region, the first region including a second plurality of partially reflective inner surfaces, the second region including a third plurality of partially reflective inner surfaces, and the first region and the second region of the first optical block are non-overlapping regions. Optionally, the third plurality of partial reflective inner surfaces are parallel to the main parallel surface of the LOE.

[0007] Optionally, each individual partial reflective inner surface in the third partial reflective inner surface lies in a plane approximately midway between a pair of principal parallel surfaces of the corresponding LOE in the LOE. 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. 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. Optionally, the first optical block is formed by joining a first constituting optical block and a second constituting optical block, each having an opposite face, such that one face of the opposite face of the first constituting optical block is connected to one face of the opposite face of the second constituting optical block. The first constituting optical block includes a second plurality of partially reflective inner surfaces, and the second constituting optical block includes a third plurality of mutually parallel partially reflective inner surfaces that are not parallel to the first plurality of partially reflective inner surfaces and are not parallel to the second plurality of partially reflective inner surfaces.

[0008] Optionally, the third optical block and the first optical structure are joined together such that substantially all of one of the faces of the third opposite side is connected to substantially all of the mating surface. Optionally, the third optical block and the first optical structure are joined together such that one of the faces of the third opposite side is connected to a portion of the mating surface. Optionally, the third optical block has an additional face, and the method further includes: obtaining an inert block having a first face and a second face; and joining the inert block and the third optical block together such that one face of the first face of the inert block is connected to one face of the additional face of the third optical block, thereby forming a composite block having a first face and a second face, the first face of the composite block being formed by one face of the third face of the inert block and one face of the second face, and the second face of the composite block being formed by the other face of the third face of the inert block and one face of the second face.

[0009] Optionally, the method further includes: obtaining a second inert block having one face; and joining the second inert block and the composite block together such that one face of one face of the second inert block is connected to a second face of the composite block. 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 a first surface of the composite block is connected to a mating surface. Optionally, the method further includes: obtaining an inert block having one opposite face; and joining the inert block and the third optical block together such that one face of the second inert block is connected to another face of the third opposite face of the optical block.

[0010] Alternatively, the stack is a stack of LOEs and multiple transparent spacers, with the LOEs and transparent spacers alternating along a length of the stack perpendicular to the main parallel surface of the LOEs. Optionally, at least two cutting planes are located in a continuous spacer plate having one of the LOEs therebetween.

[0011] According to embodiments of the teachings of the present invention, a method for manufacturing a composite light guide optical element (LOE) is also provided. The method includes: obtaining a first optical block comprising: at least a first opposite face; a first region formed by stacking LOEs, each of the LOEs having a pair of main parallel surfaces and a set of a plurality of mutually parallel partially reflective inner surfaces, the plurality of mutually parallel partially reflective inner surfaces being located between the parallel surfaces and obliquely inclined relative to the parallel surfaces, such that the first region includes a first plurality of partially reflective inner surfaces; and a second region having a second plurality of mutually parallel partially reflective inner surfaces that are not parallel to the first plurality of partially reflective inner surfaces; cutting the first optical block along a cutting plane passing through one of the faces of the first opposite face to form a first optical structure having a mating surface at the cutting plane; obtaining a second optical block having a second opposite face 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 faces of the second opposite face is connected to the mating surface, and such that the plurality of reflective inner surfaces are not parallel to both the first plurality of partially reflective inner surfaces and the second plurality of partially reflective inner surfaces, thereby forming a second optical structure; and cutting at least one composite LOE from the second optical structure by cutting the second optical structure via at least two cutting planes substantially parallel to the main parallel surfaces of the successive LOEs.

[0012] Alternatively, the stack is a stack of LOEs and multiple transparent spacers, with the LOEs and transparent spacers alternating along a length of the stack perpendicular to the main parallel surface of the LOEs. Optionally, at least two cutting planes are located in a continuous spacer plate having one of the LOEs therebetween. Optionally, the first optical block also includes an additional pair of faces, a portion of one face of the additional pair of faces formed in one of the main parallel surfaces of the LOE at the top of the stack, and a portion of another face of the additional pair of faces formed in one of the main parallel surfaces of the LOE at the bottom of the stack.

[0013] 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 located in the first sub-block region, a third plurality of mutually parallel partially reflective inner surfaces located in the second sub-block region, and the third plurality of partially reflective inner surfaces are not parallel to the first plurality of partially reflective inner surfaces and are not parallel to the second plurality of partially reflective inner surfaces. 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. 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.

[0014] According to an embodiment of the teachings of the present invention, a method for manufacturing a composite light guide optical element (LOE) is also provided. The method includes: obtaining a first optical block having a first opposite face and a first plurality of mutually parallel partially reflective inner surfaces; obtaining a second optical block formed as a stack of LOEs and having a second opposite face, each of the LOEs having a pair of main parallel surfaces and a second plurality of mutually parallel partially reflective inner surfaces inclined relative to the pair of main parallel surfaces; obtaining a third optical block having a third opposite face and a third plurality of mutually parallel partially reflective inner surfaces; joining the first and third optical blocks together and joining the second and third optical blocks together to form a fourth optical block, said joining such that: i) one face of the first opposite face is connected to one face of the third opposite face, ii) one face of the second opposite face is connected to the other face of the third opposite face, iii) the third plurality of partially reflective inner surfaces are substantially parallel to the main parallel surfaces of the LOEs, and iv) The first plurality of partially reflective inner surfaces, the second plurality of partially reflective inner surfaces, and the third plurality of partially reflective inner surfaces are not parallel to each other; a fourth optical block is cut along a cutting plane passing through another face of the first opposite face, thereby forming a first optical structure having a mating surface at the cutting plane; a fifth optical block is obtained, the fifth optical block having a fourth opposite face and a plurality of mutually parallel reflective inner surfaces; the first optical structure and the fifth optical block are joined together to form a second optical structure, the first optical structure and the fifth optical block are joined together such that one face of the fourth opposite face is connected to the mating surface, and such that the plurality of reflective inner surfaces are not parallel to the first plurality of partially reflective inner surfaces, the second plurality of partially reflective inner surfaces, and the third plurality of partially reflective inner surfaces; and at least one composite LOE is cut from the second optical structure by cutting the second optical structure via at least two cutting planes substantially parallel to the main parallel surfaces of the continuous LOE.

[0015] Optionally, the stack is a stack of joined LOEs and multiple transparent spacers, with the LOEs and transparent spacers alternating along a length of the stack perpendicular to the main parallel surface of the LOEs. Optionally, at least two cutting planes are located in a continuous spacer having one of the LOEs therebetween.

[0016] According to an embodiment of the teachings of the present invention, a method for manufacturing a composite light guide optical element (LOE) is also provided. The method includes: obtaining a first optical block having a first opposite face and a first plurality of mutually parallel partially reflective inner surfaces; obtaining a second optical block formed as a stack of LOEs and having a second opposite face, each of the LOEs having a pair of main parallel surfaces and a second plurality of mutually parallel partially reflective inner surfaces inclined relative to the pair of main parallel surfaces; obtaining a third optical block having a third opposite face and a third plurality of mutually parallel partially reflective inner surfaces; joining the first optical block and the third optical block together and joining the first optical block and the second optical block together to form a fourth optical block, said joining such that: i) one face of the third opposite face is connected to one face of the first opposite face, ii) one face of the second opposite face is connected to the other face of the first opposite face, iii) the third plurality of partially reflective inner surfaces are substantially parallel to the main parallel surfaces of the LOEs, and iv) the first plurality of partially reflective inner surfaces are inclined relative to the pair of main parallel surfaces of the LOEs. The first optical block, the second plurality of partially reflective inner surfaces, and the third plurality of partially reflective inner surfaces are not parallel to each other; a fourth optical block is cut along a cutting plane passing through another face of the third opposite face, thereby forming a first optical structure having a mating surface at the cutting plane; a fifth optical block is obtained, which has a fourth opposite face and a plurality of mutually parallel reflective inner surfaces; the first optical structure and the fifth optical block are joined together to form a second optical structure, wherein the first optical structure and the fifth optical block are joined together such that one face of the fourth opposite face is connected to the mating surface, and such that the plurality of reflective inner surfaces are not parallel to the first plurality of partially reflective inner surfaces, the second plurality of partially reflective inner surfaces, and the third plurality of partially reflective inner surfaces, thereby forming the second optical structure; and at least one composite LOE is cut from the second optical structure by cutting the second optical structure via at least two cutting planes substantially parallel to the main parallel surfaces of the continuous LOE.

[0017] Optionally, the stack is a stack of joined LOEs and multiple transparent spacers, with the LOEs and transparent spacers alternating along a length of the stack perpendicular to the main parallel surface of the LOEs. Optionally, at least two cutting planes are located in a continuous spacer having one of the LOEs therebetween.

[0018] Unless otherwise defined herein, all technical and / or scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. While methods and materials similar to or equivalent to those described herein may be used in the practice or testing of embodiments of the invention, exemplary methods and / or materials are described below. In case of conflict, this specification (including definitions) shall prevail. Furthermore, materials, methods, and examples are illustrative only and are not intended to be necessarily limiting. Simple Explanation of the Diagram

[0019] Some embodiments of the invention are described herein by way of example only with reference to the drawings. Detailed reference is made to the drawings, but it is emphasized that the details shown are by way of example and for the purpose of illustrative discussion of embodiments of the invention. In this regard, the description taken in conjunction with the drawings will make it clear to those skilled in the art how to practice embodiments of the invention. Now turn your attention to the diagrams, where the same diagrammatic symbols or characters indicate corresponding or identical parts. In the diagrams: Figures 1A to 1C are schematic side views, front views, and plan views of a composite LOE having a first LOE region and a second LOE region, respectively. The first LOE region has a first set of partially reflective inner surfaces, and the second LOE region has a second set of partially reflective inner surfaces that are not parallel to the first set of partially reflective inner surfaces. Figures 2A and 2B are schematic side and front views, respectively, of a composite LOE similar to that in Figures 1A to 1C, but including a third region, where the third region has one or more third-part reflective inner surfaces; Figure 3A is a schematic side view of an optical block of stacked LOEs, formed to be used for forming a second LOE region of a composite LOE according to an embodiment of the present invention; Figure 3B is a schematic side view of one of the stacked LOEs of Figure 3A; Figure 3C is a schematic side view of a stack of coated plates that can be cut at predetermined intervals to produce the LOE of Figure 3A. Figure 3D is a schematic side view of the LOEs arranged prior to joining to form the stack of Figure 3A; Figures 4A and 4B are schematic front and isometric views, respectively, of an optical block having multiple 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 is a schematic front view of a stack of coated plates that can be cut at predetermined intervals to produce the joints of the optical blocks of Figures 4A and 4B; Figures 5A and 5B are schematic front and isometric views, respectively, of an optical block having multiple partially reflective surfaces that can be used to form a third LOE region according to an embodiment of the present invention. Figure 5C is a schematic side view of a stack of coated plates that can be cut at predetermined intervals to produce the joints of the optical blocks of Figures 5A and 5B; Figures 6A to 6C are schematic isometric views, front views, and side views of the optical blocks of Figures 3A, 4A, 4B, 5A, and 5B aligned before being joined together, according to an embodiment of the present invention. Figures 7A to 7C are schematic isometric views, front views, and side views corresponding to Figures 6A to 6C, respectively, illustrating optical blocks joined together to form new optical blocks according to an embodiment of the present invention; Figures 8A and 8B are schematic isometric views and front views of the cutting plane according to an embodiment of the present invention, respectively, along which optical blocks in Figures 7A to 7C are cut to produce new optical structures; Figures 9A and 9B are schematic isometric views and front views of the optical structures formed by cutting the optical structures of Figures 8A and 8B along the cutting plane, respectively. Figures 10A to 10C are schematic isometric views, side views, and front views of an optical block having multiple reflective inner surfaces that can be used to form a composite LOE, according to an embodiment of the present invention. Figure 10D is a schematic side view of the jointed stack of coated plates that can be cut at predetermined intervals to produce the optical blocks of Figures 10A to 10C; Figures 11A and 11B are schematic isometric views and front views, respectively, of the alignment of the optical structures of Figures 9A and 9B and the optical blocks of Figures 10A to 10C before they are joined together according to an embodiment of the present invention. Figures 12A and 12B are schematic isometric views and front views corresponding to Figures 11A and 11B, respectively, illustrating optical structures and optical blocks joined together to form a new optical structure according to an embodiment of the present invention; Figure 13 is a schematic side view of the optical structure of Figures 12A and 12B according to an embodiment of the present invention, showing cutting planes with predetermined intervals along which the optical structure can be cut to extract one or more composite LOEs; Figures 14A to 14C are schematic side views, front views, and plan views of a composite LOE cut from the optical structures of Figures 12A and 12B after cutting the optical structure along two consecutive cutting planes of Figure 13 according to an embodiment of the present invention. Figure 15 is a schematic side view of the final composite LOE produced from the composite LOEs of Figures 14A to 14C by polishing two of the main outer surfaces of the composite LOEs of Figures 14A to 14C according to an embodiment of the present invention; Figures 16A and 16B are schematic isometric views and front views, respectively, of a reduced-size optical block similar to the optical blocks of Figures 10A to 10C according to an embodiment of the present invention, wherein the reduced-size optical block is aligned with the first and second inert blocks before being joined with the first inert block; Figures 17A and 17B are schematic isometric views and front views corresponding to Figures 16A and 16B, respectively, showing a first inert block and an optical block according to an embodiment of the present invention, which are joined together to form a composite block and aligned with a second inert block before the composite block and the second inert block are joined together; Figures 18A and 18B are schematic isometric views and front views corresponding to Figures 17A and 17B, respectively, showing a second inert block and a composite block according to an embodiment of the present invention, which are joined together to form a second composite block; Figures 19A and 19B are schematic isometric views and front views similar to Figures 12A and 12B, respectively, but show the composite block of Figures 18A and 18B joined together to form an optical structure according to an embodiment of the present invention, as well as the optical structure of Figures 9A and 9B; Figure 20A is a schematic side view similar to Figure 3D, but shows an LOE arranged in an alternating pattern with multiple transparent covers before the LOE and the transparent cover are joined together, according to an embodiment of the invention. Figure 20B is a schematic side view of the alternating LOEs and transparent cover plates of Figure 20A, which are 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 is a schematic side view of an optical structure similar to the optical structure of Figure 13 according to an embodiment of the present invention, but wherein the optical structure includes the optical block of Figure 20B; and Figure 22 is a schematic side view of a composite LOE cut from the optical structure of Figure 21 after cutting the optical structure along two consecutive cutting planes according to an embodiment of the present invention. Implementation

[0020] Embodiments of the present invention provide a method for manufacturing composite LOE.

[0021] Referring to the accompanying drawings, the principles and operation of the method according to the invention can be better understood. The drawings provide an xyz coordinate system, which is arbitrarily labeled but consistent across the drawings. This xyz coordinate system is used herein to better illustrate the disclosed embodiments by providing a common reference frame across the drawings.

[0022] Before explaining at least one embodiment of the present invention in detail, it should be understood that the invention is not necessarily limited to the details of the construction and arrangement of the components and / or methods set forth in the following description and / or illustrated in the drawings and / or examples. The invention can have other embodiments or can be practiced or performed in various ways.

[0023] Referring now to the figures, Figures 1A to 1C show various views of the composite LOE 1. The composite LOE 1 comprises a first LOE 10 and a second LOE 20 joined together at interface 40. Typically, the two LOEs 10, 20 are manufactured separately and joined together. In this document, the terms “jointed” or “jointed” should be understood to mean attached or bonded with an optical adhesive or glue or any other suitable bonding agent.

[0024] The first LOE 10 is formed of a light-transmitting material and includes: first opposing surfaces 12a, 12b (which may or may not be parallel surfaces), second opposing surfaces (main outer surfaces) 14a, 14b (which are a pair of parallel surfaces), third opposing surfaces (main outer surfaces) 16a, 16b (which may or may not be parallel surfaces), and a plurality of mutually parallel partially reflective inner surfaces (also referred to as "facets") 18, the plurality of facets passing at least partially between surfaces 16a, 16b through the LOE 10. 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), such that the light (represented in FIG. 1B by collimated image light 50) is captured in one dimension by internal reflection (preferably but not exclusively total internal reflection) at the parallel surfaces 14a, 14b of the LOE 10. LOE 10 is also configured to gradually couple the propagating (captured) light out of LOE 10 via facet 18, which is tilted obliquely to the direction of light propagation and each facet reflects a proportionate 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 light coupled out of LOE 10 via facet 18 is represented by ray 60 (Figs. 1A and 1B), and the propagation of the collimated image light 50 by inward reflection at the facets of LOE 10 is represented by left- and right-directed rays 52 (Fig. 1A).

[0025] Typically, facet 18 has a first orientation in composite LOE 1. In some embodiments, facet 18 is at an angle relative to surfaces 14, 14b. In other embodiments, facet 18 is orthogonal to surfaces 14a, 14b. It should also be noted that in some embodiments, facet 18 may be at an angle to one or both of surfaces 12a, 12b, while in other embodiments, facet 18 may be orthogonal to one or both of surfaces 12a, 12b. In the non-limiting example embodiments shown in Figures 1A and 1B, surfaces 12a, 12b are parallel, and facet 18 is obliquely inclined to surfaces 12a, 12b.

[0026] The reflectivity of the facet 18 can be provided by a coating on the inner surface before the LOE 10 is formed. The reflectivity of each of the facets 18 can be the same, or the reflectivity of the facets 18 can be different from each other, and can increase along the direction of light propagation (which is along the y-axis in the xyz coordinate system arbitrarily marked in the diagram).

[0027] Light coupled out of LOE 10 is coupled into a second LOE 20. LOE 20 is also formed of a light-transmitting material and includes: first opposing surfaces 22a, 22b (which may or may not be parallel surfaces), second opposing surfaces (main outer surfaces) 24a, 24b (which are a pair of parallel surfaces), third opposing surfaces (main outer surfaces) 26a, 26b (which may or may not be parallel surfaces), and a plurality of mutually parallel partially reflective inner surfaces (“planes”) 28 obliquely inclined relative to surfaces 24a, 24b. Surfaces 14a, 24a are substantially coincident (coplanar) to form the first single outer surface of the composite LOE 1. Similarly, surfaces 14b, 24b are substantially coincident (coplanar) to form the second single outer surface of the composite LOE 1. Faces 16a and 26a preferably overlap (coplanar) to form the third single outer face of the composite LOE 1, and faces 16b and 26b preferably overlap (coplanar) to form the fourth single outer face of the composite LOE 1. The remaining two outer surfaces of the composite LOE 1 are formed by faces 12a and 22b, respectively.

[0028] Facet 28 has a second orientation in the composite LOE 1 that is not parallel to the first orientation of facet 18. The reflectivity of facet 28 can be provided via a coating on the inner surface prior to the formation of LOE 20. The reflectivity of each of the facets 28 can be the same, or the reflectivity of the facets 28 can be different from each other, and can increase along the direction of light propagation (which is along the x-axis in the xyz coordinate system arbitrarily marked in the diagram).

[0029] Light from LOE 10 is coupled into LOE 20 via interface 40 (which coincides with surfaces 12b and 22a). LOE 20 is configured to guide the light through internal reflections (preferably, but not exclusively, total internal reflections) at surfaces 24a and 24b, and to gradually couple the propagating light from LOE 20 toward the observer's eye via facets 28 (each facet 28 reflects a proportionate intensity of the propagating light), thereby extending image illumination in the second dimension (in this case, along the x-axis). In FIG1A, the propagation of image light through LOE 20 via internal reflections at surfaces 24a and 24b is represented by groups 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 ray 60 coupled from LOE 10 into LOE 20. In FIG1A, ray 64 represents the light coupled out of LOE 20 by facets 28.

[0030] Image illumination coupled into composite LOE 1, guided by LOE 10 and LOE 20, is generated by an external image projector (not shown). This external image projector is typically implemented as a microprojector arrangement, consisting of a microdisplay device (e.g., an LCoS wafer) that generates the image illumination and collimating optics for collimating the image illumination to produce collimated image illumination. The collimated image illumination is coupled into LOE 10 via a coupling optical arrangement in the form of a highly reflective inner surface 42 in the coupling region of LOE 10.

[0031] To illuminate the LOE 20 with a collimated image while maintaining a small input aperture (small projector) (whereby the image and its conjugate propagate through the LOE via internal reflection), it is preferable to employ at least one additional partially reflective inner surface with a specific orientation relative to the facets 18, 28 and the surfaces of the composite LOE. Figures 2A and 2B illustrate a composite LOE with such an additional facet 38. The facet 38 can be deployed within a portion of the LOE 10, or as part of a separate light-transmitting substrate 30 having three opposing faces 32a, 32b, 34a, 34b, 36a, 36b (where the opposing faces 34a, 34b are a pair of parallel faces), as shown in Figures 2A and 2B. The facet 38 is parallel to the faces 14a, 14b, 24a, 24b, and therefore has an orientation that is not parallel to the orientation of the facets 18, 28. When using only a single facet 38, facet 38 is preferably located in the middle between surfaces 24a and 24b (and equivalently in the middle between surfaces 14a and 14b). If more than one facet 38 is used, the facets 38 are preferably evenly spaced between surfaces 24a and 24b. In the embodiments shown in Figures 2A and 2B, LOE 10 and substrate 30 are bonded together at surfaces 12b and 32a, and substrate 30 and LOE 20 are bonded together at surfaces 22a and 32b, such that facet 38 is located between groups of facets 18 and 28. However, it should be noted that other deployments are possible depending on the design specifications of the specific application of the composite LOE, for example, where facet 18 is located between facet 38 and groups of facets 28.

[0032] In the illustrated embodiment, light ray 60 (coupled from facet 18) is partially reflected by facet 38. The reflected and transmitted portions of light ray 60 are coupled into LOE 20 and correspond to light ray 62 and light ray 63, respectively.

[0033] Further details of composite LOEs (including composite LOEs that may be similar to those shown in Figures 1A through 2B) can be found in various publications of Lumus Ltd. (Israel), including, for example, U.S. Patent Application Publication No. 2021 / 0247608, PCT Publication WO 2021 / 240513, PCT Publication WO 2021 / 152602, PCT Publication WO 2021 / 001841 and U.S. Patent No. 10,551,544.

[0034] Embodiments of the present invention relate to a method for manufacturing a composite LOE. The composite LOE manufactured according to the method of the present invention may be structurally different from the composite LOEs shown in Figures 1A to 2B, but have similar components, as will become apparent from the following description. The manufacturing method steps are described in detail below with reference to Figures 3A to 21, and the manufacturing method steps generally include the following steps: obtaining an optical block 400 (Figures 7A to 7C) having a group of necessary facets 18, 28 (and preferably also a group of facets 38), which are embedded in a region of the optical block 400 and properly oriented relative to each other such that facets 18, 28 (and 38) are not parallel to each other; cutting a portion of the optical block 400 with a prescribed cutting plane (Figures 8A and 8B), the prescribed cutting plane being at a prescribed angle and passing through a specific face of the optical block 400 to form... An optical structure 400' is formed, having mating surfaces formed at the cutting planes (Figs. 9A and 9B); an additional optical block 500 (Figs. 10A to 10D) is obtained having a set of reflective inner surfaces 42 embedded therein; and the optical block 500 is joined to the optical structure 400' at an interface surface to form an intermediate optical structure 600 (Figs. 12A and 12B), which has a set of necessary facets 18, 28 (and preferably also a set of facets 38) embedded therein and a set of reflective inner surfaces 42 not parallel to facets 18, 28, 38. The intermediate optical structure 600 is then cut along two or more cutting planes to cut out one or more composite LOEs (Figs. 13 to 14B), wherein each composite LOE has facets 18 and 28 (and preferably also at least one facet 38) and an embedded reflective inner surface 42. Each of the cut composite LOEs can then be polished to obtain a final composite LOE with the desired thickness (Figure 15). In some embodiments, one or more blocks 800, 900 of inert material are joined to optical block 500 to form composite block 590 (Figures 16A to 18B), and then composite block 590 is joined to optical structure 400' (Figures 19A and 19B) to form intermediate optical structure 600. As will be discussed, obtaining optical block 400 may include producing optical block 400 by obtaining various other optical blocks 100, 200, 300 (Figures 3A to 5C) and joining these optical blocks 100, 200, 300 together to form optical block 400. Each of optical blocks 100, 200, 300 has one of the necessary grouped facets 18, 28, 38 embedded therein, and may be produced by a grouped coated plate cut at appropriate angles and thicknesses.

[0035] It should be noted that in the drawings, and according to a set of non-limiting embodiments of the invention, each of the blocks 100, 200, 300, 400, 500, 800, and 900 is represented as a rectangular cube, i.e., a structure having three pairs of mutually perpendicular (orthogonal) parallel faces. However, the blocks are represented as rectangular cubes only for clarity of presentation, and from an optical or manufacturing point of view, the parallelism and perpendicularity between all faces of the blocks are not strictly required. In many embodiments, only one pair of faces of a block needs to be a pair of parallel faces, while the remaining faces may or may not be parallel. In other embodiments, no face of a block needs to be a pair of parallel faces.

[0036] The following paragraphs describe the structure and manufacture of the optical block 200 with reference to Figures 3A to 3D. Referring first to Figure 3A, the optical block 200 is shown, which is formed as a stack of LOEs 20 joined together. The optical block 200 has at least two opposite faces (main outer surfaces), namely a pair of preferred parallel surfaces 212a, 212b, and an opposite face 214a, 214b, which are a pair of parallel surfaces and may be orthogonal (perpendicular) to any one or both of surfaces 212a, 212b. The optical block 200 also includes a third opposite face, which may or may not be a pair of parallel surfaces and may also be perpendicular to one or more of surfaces 212a, 212b, 214a, 214b. The third opposite face is not shown in Figure 3A but is shown in various other figures including Figures 6B, 7B, 8B, 9B, 11B, 12B, and 19B. As will become apparent, surfaces 214a and 214b can form part of the upper and lower surfaces of the optical structure 600 (Figs. 11C and 11D), from which a composite LOE can be cut out.

[0037] Each of the LOEs 20 in the stack of Figure 3A is the LOE shown in Figure 3B. This LOE 20 is generally also similar to the second LOE 20 discussed above with reference to Figures 1A to 2C. As shown in Figure 3B, and as discussed above with reference to Figures 1A to 2C, each LOE 20 is formed of a light-transmitting material, and each LOE has parallel surfaces 24a, 24b and a set(s) of internal facets 28 obliquely inclined to surfaces 24a, 24b. Such LOEs can be used as standalone LOEs (along with suitable coupling optics) where only one-dimensional aperture expansion is desired. This type of LOE is commonly referred to as a “one-dimensional” LOE, and the structure and methods for manufacturing such a one-dimensional LOE have been extensively described in various publications of Lumus Ltd. (Israel), including, for example, U.S. Patent No. 7,634,214, U.S. Patent No. 8,873,150, PCT Publication WO 2016 / 103263, and PCT Publication WO 2020 / 212835.

[0038] Figure 3C illustrates an example method for manufacturing multiple LOEs 20 that can be used to produce an optical block 200. In Figure 3C, multiple light-transmitting plates are coated to form coated plates 202 that are stacked and bonded together, and then cut along equally spaced parallel cutting planes 206 (which are parallel to the xy plane in an arbitrarily labeled xyz coordinate system). Each of the coated plates 202 has a pair of parallel surfaces 204a, 204b, which are suitably coated with a coating that provides reflectivity to a facet 28 (such that the facet 28 is partially reflective). The cutting planes 206 are inclined relative to the surfaces 204a, 204b and define the inclination angle of the facet 28, and the resulting cuts along the cutting planes 206 define the surfaces 24a, 24b of the LOEs 20. The cutting planes 206 are spaced apart at predetermined intervals. Preferably, the predetermined intervals are uniform, such that the cutting planes 206 are evenly spaced apart. The uniform spacing is preferably in the range of 1 mm to 2 mm, so that the thickness of each LOE 20 (measured between faces 24a and 24b) is approximately 1 mm to 2 mm.

[0039] Before joining the LOEs 20 together to form the optical block 200, the LOEs 20 are first aligned and arranged according to arrangement 210 (Fig. 3D). Then, the LOEs 20 arranged 210 are joined together to form a stacked optical block 200 as the joints of the LOEs 20 (Fig. 3A), such that the faces 24a and 24b of adjacent (continuous) LOEs 20 are connected at the joint area, and the grouped internal facets 28 of the LOEs 20 constitute a plurality of facets 28 of the optical block 200. As can be seen from Figs. 3A and 3D, the main surface 24a of the LOEs 20 at the top of the stack 200 forms the top surface 214a of the stack 200, and the main surface 24b of the LOEs 20 at the bottom of the stack 200 forms the bottom surface 214b of the stack 200.

[0040] The following paragraphs describe the structure and manufacture 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 of a light-transmitting material and has embedded groups of facets 18. The optical block 100 includes three opposing surfaces (main outer surfaces): one pair of opposing surfaces 112a, 112b (which may or may not be parallel surfaces), a pair of preferably parallel surfaces 114a, 114b, and a pair of surfaces 116a, 116b (which may or may not be parallel surfaces). In some embodiments, the opposing surfaces of the optical block 100 are orthogonal (perpendicular) to each other, which simplifies the manufacturing process.

[0041] The optical block 100 can be formed from a plurality of joined transparent coated plates 102 (each plate being formed of a light-transmitting material and coated with a partially reflective coating) to form a facet 18 at a predetermined angle relative to surfaces 114a, 114b, i.e., the facet 18 can be obliquely inclined relative to surfaces 114a, 114b or can be orthogonal to surfaces 114a, 114b. The facet 18 can also be obliquely inclined relative 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 stacked and joined together (as similar to that in Figure 3C), and then cut along a first pair of preferably parallel cutting planes 104 and a second pair of preferably parallel cutting planes 106 preferably perpendicular to the cutting planes 104 to extract the optical block 100. In embodiments where the facet 18 is inclined relative to one or both of the surfaces 112a and 112b, the angle of the cutting plane 104 relative to the surface of the coating plate 102 determines the angle of inclination of the facet 18 relative to the surfaces 112a and 112b. Furthermore, the cutting along the cutting plane 104 defines the surfaces 112a and 112b of the optical block 100, and the cutting along the cutting plane 106 defines the surfaces 116a and 116b of the optical block 100.

[0042] In some embodiments, such as the one shown in FIG. 4C, the cutting planes 104 and 106 are perpendicular to the thickness dimension of the coating plate 102, such that the resulting facet 18 is perpendicular to the surfaces 114a and 114b of the optical block 100. In the xyz coordinate system of arbitrary designation used in the figures, when the cutting planes 104 and 106 are perpendicular to the thickness dimension of the coating plate 102, the cutting plane 104 is parallel to the yz plane and the cutting plane 106 is parallel to the xz plane. The cutting plane 106 is perpendicular to the cutting plane 104.

[0043] As described above, other embodiments are possible, wherein the facet 18 is obliquely inclined relative to the surfaces 114a, 114b, and therefore the cutting plane 106 may be inclined at an appropriate angle relative to the xz plane to produce an appropriate facet angle relative to the surfaces 114a, 114b.

[0044] The following paragraphs describe the structure and fabrication 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 of a light-transmitting material and has embedded groups of facets 38. The optical block 300 includes three opposing surfaces (main outer surfaces): one pair of opposing surfaces 312a, 312b (which may or may not be parallel surfaces), a pair of preferably parallel surfaces 314a, 314b, and a pair of surfaces 316a, 316b (which may or may not be parallel surfaces). In some non-limiting embodiments, the opposing surfaces of the optical block 100 are orthogonal (perpendicular) to each other.

[0045] Optical block 300 can be formed from multiple joined transparent coated plates 302 (each plate being formed of a light-transmitting material and coated with a partially reflective coating) to form small planes 38 parallel to surfaces 314a, 314b and optionally perpendicular to one or both surfaces 312a, 312b. Various known methods exist for forming optical block 300. Figure 5C illustrates one such method in which coated plates 302 are stacked and joined (as similar to those in Figures 3C and 4C), and then cut along a pair of cutting planes 304 to extract optical block 100. In some embodiments, such as the one shown in Figure 5C, the cutting planes 304 are parallel planes (parallel to the yz plane in an arbitrarily labeled xyz coordinate system). However, as mentioned above, the parallelism between the cutting planes 304 is not strictly required, and in some cases, it is advantageous to cut along non-parallel cutting planes, which can improve the compactness and overall form factor of the final composite LOE product. In some embodiments, the cutting planes 304 are perpendicular to the main outer surface (face) of the coated plate 202. However, this perpendicularity is not an optical requirement for producing the final composite LOE product, but rather a matter of practical convenience in manufacturing the composite LOE. The stacked and joined plates can also be cut along another pair of cutting planes 306, which pass through both plates and can be parallel to the main outer surface of the coated plate 202 and perpendicular to the cutting planes 304. In the xyz coordinate system used arbitrarily in the figures, the cutting planes 306 are parallel to the xy plane.

[0046] Continuing with reference to Figures 1A to 5C, now referring to Figures 6A to 6C, which show the three optical blocks 100, 200, and 300 before they are joined together to form optical block 400 (Figures 7A to 7C). Before joining, it is important to properly align optical blocks 100, 200, and 300 such that the orientation of facet 18 is not parallel to the orientation of facet 28, and that the orientation of facet 38 is not parallel to the orientations of facets 18 and 28. In other words, align optical blocks 100, 200, and 300 such that facets 18, 28, and 38 are not parallel to each other.

[0047] Preferably, optical block 300 is aligned with optical block 200 such that the facet 38 of optical block 300 lies in a plane parallel to the planes of faces 214a and 214b of optical block 200. In embodiments where each composite LOE will have only a single facet 38, optical blocks 200 and 300 are preferably aligned such that each corresponding facet 38 lies in a plane approximately midway between the main outer surfaces 24a and 24b of the corresponding LOE in the LOE 20 forming optical block 200. In embodiments where each composite LOE will have multiple facets 38 (e.g., N facets 38), optical blocks 200 and 300 are preferably aligned such that for each group of N facets 38, the N facets 38 are uniformly spaced between the main outer surfaces 24a and 24b of the corresponding LOE in the LOE 20 forming optical block 200. However, it should be noted that the optical block 300 can be positioned relative to the optical block 200 without much careful inspection of the positioning of the facet 38 relative to the main outer surfaces 24a, 24b, and any mispositioning of the facet 38 relative to the main outer surfaces 24a, 24b in the cut composite LOE can be corrected in the final stage of manufacturing (usually by polishing or grinding) if there is sufficient spare area in the cut composite LOE.

[0048] Referring to the coordinate system shown in Figures 6A to 6C, the alignment of optical blocks 100, 200, and 300 (when 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 small facets 38 lies in a plane parallel to the xy plane.

[0049] To reduce waste, optical blocks 100, 200, and 300 are preferably designed to have the same or very close same dimensions, namely length, width, and thickness. The length is measured along the y-axis (i.e., between surfaces 116a, 116b, 216a, 216b, and 316a, 316b) in an arbitrary xyz coordinate system as indicated in the diagram. The width is measured along the x-axis (i.e., between surfaces 112a, 112b, 212a, 212b, and 312a, 312b) in an arbitrary xyz coordinate system as indicated in the diagram. The thickness is measured along the z-axis (i.e., between surfaces 114a, 114b, 214a, 214b, and 314a, 314b) in an arbitrary xyz coordinate system as indicated in the diagram.

[0050] Using optical blocks 100, 200, and 300 with the same (or very close to the same) thickness is crucial for minimizing waste from the final cutting step to cutting out the composite LOE. Therefore, in a particularly preferred embodiment, the optical blocks 100, 200, and 300 are aligned such that: surfaces 114a, 214a, and 314a are coplanar (i.e., located in a common plane), surfaces 114b, 214b, and 314b are coplanar, surfaces 112a, 212a, and 312a are coplanar, surfaces 112b, 212b, and 312b are coplanar, surfaces 116a, 216a, and 316a are coplanar, and surfaces 116b, 216b, and 316b are coplanar.

[0051] Once properly aligned, as shown in Figures 7A to 7C, optical blocks 100, 200, and 300 are joined together to form optical block 400 (which is a composite optical block comprising multiple sub-blocks), while maintaining the alignment described with reference to Figures 6A to 6C. In the illustrated embodiment, optical block 400 is a rectangular cube and has three regions: one region having optical blocks (stacked) 200 carrying a bonding LOE 20 with a facet 28, another region having optical block 300 carrying a facet 38, and another region having optical block 100 carrying a 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 this embodiment, surfaces 112a and 212b form the first pair of parallel surfaces 412a and 412b of the optical block 400; surfaces 414a (formed by coplanar surfaces 114a, 214a, and 314a) and 414b (formed by coplanar surfaces 114b, 214b, and 314b) form the second pair of parallel surfaces of the optical block 400; and surfaces 416a (formed by coplanar surfaces 116a, 216a, and 316a) and 416b (formed by coplanar surfaces 116b, 216b, and 316b) form the third pair of parallel surfaces of the optical block 400. It should be noted that in embodiments where the optical block 400 is not a rectangular cube, any pair of the three pairs of surfaces 412a, 412b, 414a, 414b, 416a, and 416b does not necessarily have to be a pair of parallel surfaces.

[0052] As can be seen from Figures 3A, 3D, 7A and 7D, the main surface 24a of the LOE 20 at the top of the stack 200 forms part of the top surface 414a of the optical block 400, and the main surface 24b of the LOE 20 at the bottom of the stack 200 forms part of the bottom surface 414b of the optical block 400.

[0053] In some embodiments, optical blocks 100, 200, and 300 can be joined together in stages. For example, optical blocks 200 and 300 can be joined together, and then optical blocks 100 and 300 can be joined together. Alternatively, optical blocks 100 and 300 can be joined together, and then optical blocks 200 and 300 can be joined together. Optical blocks 200 and 300 are joined together such that surface 312b is connected to surface 212a. Optical blocks 100 and 300 are joined together such that surface 112b is connected to surface 312a. As a result of the joining (and proper alignment) of optical blocks 100, 200, and 300, facet 18 is not parallel to facet 28.

[0054] In some embodiments, such as the one shown in the figures, optical blocks 100, 200, and 300 are arranged such that optical block 300 is positioned between optical blocks 100 and 200, and facet 38 is located between facets 18 and 28. However, other embodiments are possible, wherein the order of the optical blocks differs from that shown in the figures, for example, where optical block 100 is positioned between optical blocks 200 and 300, and facet 18 is located between facets 28 and 38. In such an embodiment, surface 312a of optical block 300 forms surface 412a of optical block 400.

[0055] The embodiments described so far involve using three optical blocks to form a composite optical block 400. However, in some embodiments, optical block 300 may be omitted or replaced by one or more optical blocks carrying a plane with a different orientation from the plane 38. Therefore, optical block 400 can generally be considered as being formed by two optical sub-blocks and having two regions, wherein optical block 200 with plane 28 forms a first sub-block (first region), and optical block 100 with plane 18 forms a second sub-block (second region). In the embodiment shown in the figures, the second sub-block includes two sub-sub-blocks (two sub-regions), wherein plane 18 is located in the first sub-sub-block (first sub-region), in which case the first sub-sub-block is optical block 100, and plane 38 is located in the second sub-sub-block (second sub-region), in which case the second sub-sub-block is optical block 300.

[0056] In an embodiment where optical block 300 is omitted, optical blocks 100 and 200 are joined together to form optical block 400, such that surface 112b is connected to surface 212a. As a result of the joining (and proper alignment) of optical blocks 100 and 200, facet 18 is not parallel to facet 28.

[0057] Continuing with reference to Figures 1A through 7B, now referring to Figures 8A through 9B, which illustrate the steps (Figures 8A and 8B) for cutting optical block 400 and the results of cutting optical block 400 (Figures 9A and 9B). Generally, as shown in Figures 8A and 8B, optical block 400 is cut along a cutting plane 402 that passes through surface 412a (surface 112a in the illustrated embodiment, but surface 312a in embodiments where the positions of optical blocks 100 and 300 are interchanged) and at least one of surfaces 116a, 216a, and 316a. In embodiments where surfaces 116a, 216a, and 316a are coplanar and form surface 416a, cutting plane 402 passes through surface 416a. The cutting plane 402 is positioned such that it passes through at least a portion of an optical sub-block having facet 18 or facet 38. In the illustrated embodiment, cutting plane 402 passes through a portion of an optical sub-block having facet 18, which in the illustrated embodiment is optical block 100. However, in some practical implementations, the cutting plane 402 can pass through all three regions of the optical block 400 (i.e., through the regions that combine the facets 18, 38, and 28).

[0058] In some embodiments, depending on the construction of the optical block 400, the cutting plane 402 is inclined relative to surface 412a (112a or 312a), and may also be inclined relative to one or more of surfaces 116a, 316a, 412b, 112b, 312a, 312b, 212a. The cutting plane 402 is preferably perpendicular to surface 114a (and therefore also perpendicular to surfaces 314a, 214a in embodiments where surfaces 114a, 314a, 214a are parallel). Cutting the optical block 400 along the cutting plane 402 results in the formation of an optical structure 400' having a mating surface 404 (or "surface" 404) at the location of the cutting plane 402, as shown in Figures 9A and 9B.

[0059] In some embodiments where optical block 400 includes three optical blocks 100, 200, and 300 as shown in Figures 7A to 7C, the position of the cutting plane 402 can be restricted such that the cutting plane 402 passes only through a portion of optical block 100 and not through any of the other optical blocks 200 and 300, such that the portion to be cut is only a portion of optical block 100. However, in other embodiments, the position of the cutting plane 402 can allow the cutting plane 402 to pass through a portion of optical block 300 and also through a portion of optical block 200.

[0060] In the embodiment where surfaces 116a, 216a, and 316a are coplanar and combined to form surface 416a, the portion of optical block 400 that is cut off (i.e. removed) is a triangular prism (typically a right-angled triangular prism) portion (represented by 401 in Figures 8A and 8B). In the embodiment where optical block 300 is sandwiched between optical blocks 100 and 200, the triangular prism portion 401 includes a portion (typically all) of surface 116a and a portion of surface 112a (which may be a small portion, for example, approximately 10% to 20%).

[0061] In some embodiments where the positions of optical blocks 100 and 300 are interchanged, such that optical block 100 is sandwiched between optical block 300 and optical block 200, the position of the cutting plane can be restricted such that the cutting plane 402 passes only through a portion of optical block 300 and does not pass through any of the other optical blocks 100 and 200, so that the portion to be cut is only a portion of optical block 300. However, similar to the above, in some embodiments, the cutting plane 402 may pass through a portion of optical block 100 and also through a portion of optical block 200.

[0062] Figures 9A and 9B show an optical structure 400' with a mating surface 404 formed by cutting the optical block 400 along the cutting plane 402 and removing the triangular prism portion 401. The optical block 500 with a coupling reflector is joined to the optical structure 400' at the mating surface 404.

[0063] The following paragraphs describe the structure and fabrication 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 of a light-transmitting material and has a set of reflective inner surfaces 42 (high-reflectivity mirrors), each of which serves as the coupling configuration for the final composite LOE. The optical block 500 includes three opposing surfaces (main outer surfaces): a pair of preferably parallel surfaces 512a, 512b; an opposing surface 514a, 514b (which may or may not be parallel); and an opposing surface 516a, 516b (which may or may not be parallel). In some embodiments, the three opposing surfaces of the optical block 500 are mutually orthogonal (perpendicular); however, other embodiments in which the three opposing surfaces are not mutually orthogonal may be preferred.

[0064] Optical block 500 can be formed from multiple joined transparent coated plates 502 (each plate being formed of a light-transmitting material and coated with a partially reflective coating) to form a reflective inner surface 42, which is obliquely inclined at a predetermined angle to one or both of surfaces 512a, 512b. Various known methods exist for forming optical block 500. Figure 10D illustrates one such method in which the coated plates 502 are stacked and joined (similar to those in Figures 3C, 4C, and 5C) and then cut along equally spaced parallel cutting planes 504 (which are 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 optical block 500. Unlike the coatings used to produce facets 18, 28, 38, the coating used to form the coated plates 502 is not partially reflective but fully (and preferably highly) reflective, such that the resulting reflective inner surface 42 acts as a perfect reflector. A dielectric coating is an example of a suitable coating that can be used to form the reflective inner surface 42. The cutting plane 504 is at an angle to the coating surface of the coating plate 502, wherein the angle of inclination of the cutting plane 504 determines the angle of inclination of the reflective inner surface 42 relative to the surfaces 512a and 512b.

[0065] In some embodiments, each of the optical structures 505 can be cut along two additional parallel planes 506, 508 perpendicular to the cutting 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, planes 506, 508 are parallel to the xy plane.

[0066] Continuing with reference to Figures 8A through 10D, and also focusing on Figures 11A and 11B, which show the optical block 500 and optical structure 400' before being joined together to form optical structure 600 (Figures 12A and 12B). Before joining, it is important to properly align the optical block 500 and optical structure 400' such that the orientation of the reflective inner surface 42 is not parallel to the orientation of the facets 18, 28, 38 (i.e., such that the reflective inner surface 42 is not parallel to the facets 18, 28, 38), and such that each reflective inner surface 42 is associated with a corresponding LOE 20 in the optical block 200 such that the projection of the inner surface on the thickness dimension of the corresponding LOE (which is the yz plane in the xyz coordinate system arbitrarily marked in the figures) is defined by the main surfaces 24a, 24b of the LOE 20.

[0067] In some embodiments, it is also 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.

[0068] To avoid waste in the final cutting step used to cut out the composite LOE, optical block 500 preferably has the same thickness (measured along the z-axis, i.e., between surfaces 514a and 514b) as optical blocks 100, 200, and 300, and therefore the same thickness as optical structure 400'. In such an embodiment, the alignment of optical block 500 and optical structure 400' preferably makes surfaces 514a and 414a coplanar, and similarly, surfaces 514b and 414b coplanar. In such an embodiment, the alignment of optical block 500 and optical structure 400' also makes surfaces 512b and 404 aligned and virtually coincident.

[0069] Once properly aligned, as shown in Figures 12A and 12B, the optical block 500 and the optical structure 400' are joined together to form the optical structure 600 (an intermediate working product in the composite LOE manufacturing process). The joining of the optical block 500 and the optical structure 400' connects surface 512b to surface (mating surface) 404 while maintaining the aforementioned alignment. Preferably, surfaces 512b and 404 are the same size, or very close to being the same size. In some embodiments, the alignment of the optical block 500 with the optical structure 400' may further include twisting or rotating surface 512b relative to the mating surface 404, such that the reflective inner surface 42 is tilted at an angle relative to the optical structure 400' in addition to being tilted relative to one or both of surfaces 512a and 512b. In the figures, such tilt angles and angles correspond to the reflective inner surface 42 being tilted at two angles relative to the xy plane.

[0070] As shown in Figure 13, after forming the optical structure 600, the optical structure 600 is cut (slice-cut) at predetermined intervals along two or more preferably parallel cutting planes 602 to extract one or more composite LOEs. The cutting planes 602 are preferably parallel to the main outer surfaces 24a, 24b of the LOEs 20 forming the optical block 200. Most preferably, the continuous cutting planes 602 are located between the surfaces 24a, 24b of the continuous LOEs 20, particularly in the joint region between the surfaces 24a, 24b of the continuous LOEs 20. For example, the first cutting plane 602-1 in the cutting plane 602 passes through the joint area between the second surface 24b-1 of the first LOE 20 and the first surface 24a-2 of the second LOE 20 (adjacent to and joined to the first LOE 20-1), and the second cutting plane 602-2 of the cutting plane 602, adjacent to the first cutting plane 602-1, passes through the joint area between the second surface 24b-2 of the second LOE 20 and the first surface 24a-3 of the third LOE 20 (adjacent to and joined to the second LOE 20-2). It should be noted herein that the joint area (formed between the surfaces 24a, 24b of the consecutive LOE 20) can provide guidance for the placement of the cutting plane 602. It should also be noted that minor deviations in parallelism with the cutting plane can be corrected by polishing the composite LOE along the two main surfaces, the parallelism of which causes the two main surfaces of the cut composite LOE to be approximately parallel but not completely parallel, formed by cutting along the continuous cutting plane 602.

[0071] Referring also to Figures 14A to 14C, a composite LOE 700 cut from the optical structure 600 after cutting along the cutting plane 602 is shown. The composite LOE 700 includes: a first pair of opposite faces 712a, 712b (which include portions of faces 412a, 412b, and faces 712a, 712b may or may not be parallel faces); a second pair of parallel faces 714a, 714b (main surfaces) formed by cutting the optical structure 600 along the continuous cutting plane 602 (and preferably partially formed by surfaces 24a, 24b of one of the LOE 20); and a third pair of opposite faces 716a, 716b (which include portions of faces 416a, 416b, and faces 716a, 716b may or may not be parallel faces). Most notably, the composite LOE 700 has: a first plurality of small facets 18 (in the first LOE region 710), which have a first orientation and may also be obliquely inclined or orthogonal to the faces 714a, 714b; a second plurality of small facets 28 (in the second LOE region 720), which are obliquely inclined relative to the faces 714a, 714b and have an orientation that is not parallel to the orientation of the small facets 18; and at least one small facet 38, which is located in the region 730 between the first LOE region and the second LOE region and has an orientation that is parallel to the faces 714a, 714b and not parallel to the orientation of the small facets 18, 28. The composite LOE 700 also includes a (high)reflective inner surface 42 (also referred to as a coupling reflector), which is located in a coupling region 750 defined by surfaces 512a, 514a', 514b', 516a, 516b, and has an orientation that is not parallel to the orientation of facets 18, 28, 38 (i.e., the inner surface 42 is not parallel to facets 18, 28, 38). Surfaces 514a' and 514b' are parallel to each other and form part of surfaces 714a and 714b. In embodiments where surface 512b of optical block 500 (or surface 512b' of optical block 500' or surface 582 of block 580 / 590) is twisted or rotated relative to mating surface 404, the inner surface 42 is skewed about two axes relative to the waveguide axes (which may be skew angles measured relative to the x-axis and y-axis in an xyz coordinate system arbitrarily marked in the diagram).

[0072] It should be apparent that, unlike the composite LOE shown in Figures 1A to 2B, the composite LOE 700 does not have a rectangular cross-section in the two-dimensional plane (most notably in the xy plane shown in Figure 14B) due to the cutting and joining steps described above with reference to Figures 8A to 12B.

[0073] After cutting out the composite LOE 700, each of the composite LOEs can be polished on the outer surfaces 714a and 714b to form a final composite LOE with the desired thickness (measured along the z-axis in the xyz coordinate system arbitrarily marked in the diagram), and to ensure parallelism between surfaces 714a and 714b (and optional facets 38). Figure 15 shows a view of the resulting polished composite LOE, where parallel surfaces 714a' and 714b' correspond to the polished surfaces 714a and 714b.

[0074] The composite LOE produced using the manufacturing process according to the embodiments disclosed herein offers several advantages over composite LOEs produced using conventional manufacturing methods. First, the cutting plane 402 is positioned at a designated area of ​​the optical block 400 (Figures 8A and 8B) to accommodate the placement of the coupling reflector 42 in an area that presents a more aesthetically pleasing overall design of the composite LOE 700. Furthermore, the spatial positioning of the coupling reflector 42, determined by the bevel angles of the cutting plane 402 and the cutting plane 504 (Figure 10D), determines the spatial orientation of the image projector that generates the collimated image light. In the disclosed embodiments, the spatial orientation of the coupling reflector 42 can be designed to accommodate the spatial positioning of the image projector below the composite LOE associated with a portion of the surface 714b' of the coupling region 750, thereby providing an aesthetically pleasing placement of the image projector and reducing the overall shape factor of the optical system formed by the composite LOE and the image projector, which can be implemented as part of a head-mounted display and, in some non-limiting implementations, as part of the eyeglass shape factor. Furthermore, compared to conventional manufacturing methods used to produce composite LOEs, the reduction in raw material waste achieved through the disclosed manufacturing process and the fact that a large number of composite LOEs can be cut from a single optical structure 600 contribute to the large-scale production of composite LOEs while maintaining low manufacturing costs.

[0075] As mentioned, the composite LOE according to the disclosed embodiments can be attached or otherwise coupled to an image projector that generates collimated image light that can be coupled into the composite LOE via the reflective inner surface 42. In a preferred embodiment, the coupling reflector is designed to accommodate the spatial positioning of the image projector below the composite LOE. For both functional and aesthetic reasons, it is generally desirable that the collimated image light corresponding to the principal ray of the central field of view should generate an approximately perpendicular angle (up to approximately 20°) relative to the composite LOE at the input from the image projector to the composite LOE (i.e., via coupling into the first LOE region from the reflective inner surface 42) and at the output from the composite LOE to the observer's eye (i.e., via the plane 28 from the second LOE region). Therefore, it is preferable that the reflective inner surface 42 and the plane 28 have similar elevation angles. In other words, the angle of the reflective inner surface 42 measured relative to surfaces 512a and 512b is generally approximately equal to the angle of the facet 28 measured relative to surfaces 714a' and 714b' (or the angle of the facet 28 equivalently measured relative to surfaces 24a and 24b that constitute the composite LOE 20).

[0076] In many cases, only a portion of the reflective inner surface 42 provides a useful effective area for coupling light from the image projector into the composite LOE, while the remainder of the reflective inner surface 42 either does not couple any light into the composite LOE or couples light at an angle that produces unwanted reflections at the main surface of the composite LOE, causing ghosting images. Furthermore, the reflective coating used to form the coating plate 502 (FIG. 10D) for producing the reflective inner surface 42 is typically costly, and therefore reducing any unused (i.e., “ineffective”) area of ​​the reflective inner surface 42 can reduce manufacturing costs. Therefore, to reduce manufacturing costs and mitigate ghosting images by preventing or reducing unwanted reflections, it may be advantageous to limit the size of the reflective inner surface 42 to the effective area and fill the remaining area with a cheaper, inert material (e.g., glass, plastic, or even metal).

[0077] Referring also to Figures 16A through 18B, the following paragraphs describe an embodiment in which a reduced-size optical block 500', joined together with one or more blocks 800, 900 of an inert material such as, for example, glass, plastic, or metal, produces a reduced-size reflective inner surface 42. The materials used to form the blocks 800, 900 (which are interchangeably referred to herein as “inert blocks”) can be the same or different. For example, blocks 800, 900 can both be formed of glass, or one block can be formed of glass while the other is formed of plastic. The optical block 500' is structurally similar to the optical block 500, with the notable exception that the length of the optical block 500' (measured along the y-axis in the xyz coordinate system as arbitrarily marked in the diagrams) is reduced compared to the length of the optical block 500, thereby limiting the size of the reflective inner surface 42 to only the useful effective area. Due to the structural similarity of the optical blocks 500', the same diagrammatic designations will be used to identify the same components, with an apostrophe (“’”) appended to the diagrammatic designation of the optical block 500'.

[0078] The inert block 800 has three opposite faces (main outer surfaces): a first pair of preferably parallel faces 812a, 812b; a second pair of opposite faces 814a, 814b (which may or may not be parallel); and a third pair of opposite faces 816a, 816b (which may or may not be parallel). The optical block 500' is limited in size by the inert block 800, and therefore the inert block 800 can be understood as acting as a ghosting reduction element, which limits the size of the reflecting inner surface 42 to only a useful effective area. In some embodiments, the block 800 is a rectangular cube.

[0079] The inert block 900 also has three pairs of parallel faces (main outer surfaces): a first pair of preferably parallel faces 912a, 912b; a second pair of parallel faces 914a, 914b (which may or may not be parallel); and a third pair of parallel faces 916a, 916b (which may or may not be parallel). In some embodiments, the block 900 is a rectangular cube. As will be discussed, the block 900 is optional, but can be advantageously used to provide structural reinforcement and support for the optical block 500'.

[0080] The joining is preferably performed in stages, wherein optical blocks 500' and 800 are first joined together to form composite block 580. Optical 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 optical blocks 500' and 800 (when each of optical blocks 500' and 800 is constructed 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 coincident in a plane parallel to the xz plane.

[0081] Optical blocks 500' and 800 are joined together to form composite block 580, such that surface 516b' is connected to surface 816a, while maintaining the alignment described with reference to Figures 16A and 16B. Block 580 is shown in Figures 17A and 17B, and block 580 has: a first pair of preferably parallel surfaces 582a, 582b formed by surfaces 512a', 812a and 512b', 812b respectively; a second pair of opposite surfaces 584a, 584b (which may or may not be parallel surfaces) formed by surfaces 514a', 814a and 514b', 814b respectively; and a third pair of opposite surfaces 516a', 816b (which may or may not be parallel surfaces). The reflective inner surface 42 is in the first region of block 580 and is obliquely inclined relative to surfaces 582a, 582b.

[0082] In some embodiments, blocks 580 and 900 can then be joined together to form composite block 590, as shown in Figures 18A and 18B. Blocks 580 and 900 are properly aligned before being joined together. Referring to the coordinate system 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 are in a plane parallel to the xz plane and preferably coplanar; faces 516b' and 916b are in a plane parallel to the xz plane and preferably coplanar; faces 584a and 914a are in a plane parallel to the xy plane and preferably coplanar; faces 584b and 914b are in a plane parallel to the xy plane and preferably coplanar; and faces 582a and 912b are aligned and coincident in a plane parallel to the yz plane.

[0083] Blocks 580 and 900 are joined together to form 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 is shown in Figures 18A and 18B, and block 590 has: a first pair of parallel faces 912a and 582b; a second pair of opposite faces 594a and 594b formed by faces 914a and 584a and 914b and 584b respectively (which may or may not be parallel faces); and a third pair of opposite faces 596a and 596b formed by faces 916a and 586a and 916b and 586b respectively (which may or may not be parallel faces).

[0084] Then, similar to what is described with reference to Figures 11A to 12B, block 590 can be aligned and joined to optical structure 400' instead of optical block 500. When block 590 is used instead of optical block 500, joining block 590 to optical structure 400' causes surface 582b to be connected to mating surface 404, as shown in Figures 19A and 19B. Therefore, only a small portion of mating surface 404 is connected to surface 512b' (which forms a portion of surface 582b). This contrasts with the embodiments shown in Figures 12A and 12B, where the entire surface 512b is connected to the entire mating surface 404. The optical structure formed by joining block 590 and optical structure 400' can then be sliced ​​at predetermined intervals demarcated by parallel cutting planes to extract one or more composite LOEs, similar to what is described with reference to Figure 13.

[0085] In some embodiments, the inert block 900 can be joined without the inert block 800 to provide structural reinforcement and support for the optical block 500. For example, in one embodiment, the inert block 900 and the optical block 500 are joined together to form an intermediate block, such that face 912b is connected 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.

[0086] In another similar embodiment, the inert block 900 and the optical block 500' are joined together without the presence of block 800. In such an embodiment, the joining is 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 being joined together. Alternatively, the size of the inert block 900 can be reduced to match the size of the optical block 500'.

[0087] In some embodiments, it may be advantageous to provide a transparent cover on one or both polished surfaces 714a', 714b' of the cut composite LOE (e.g., the composite LOE shown in FIG. 15). In some embodiments, such a transparent cover may be provided directly to surfaces 714a', 714b' (i.e., after the cut composite LOE has been polished).

[0088] In other embodiments, as shown in Figures 20A and 20B, transparent cover plates can be provided as spacers between LOEs 20 during the production of optical blocks 200. Referring first to Figure 20A, an alignment arrangement 220 of LOEs 20 and transparent cover plates 220 is shown, wherein LOEs 20 and cover plates 230 alternate along a length of the arrangement 220 perpendicular to the parallel planes 24a, 24b of LOEs 20 (here the length is along the z-axis). Each cover plate 230 has a pair of parallel outer faces 231a, 231b. As shown in Figure 20B, cover plates 230 and LOEs 20 are joined together to form a joined stack 200' (also referred to as optical blocks 200'). The joining is such that the faces 231b, 24a of adjacent cover plates 230 and LOEs 20 are joined, and the faces 231a, 24b of adjacent cover plates 230 and LOEs 20 are joined.

[0089] Stack 200' is generally structurally similar to stack 200 of Figure 3A (i.e., stack 200' has three pairs of parallel faces and is formed by multiple joined LOEs), and the same schematic designations will be used to represent the same elements. A significant difference between stack 200 and stack 200' is that stack 200' is a stack of joined LOEs 20 and cover plates 230, wherein the LOEs 20 and cover plates 230 alternate along the length of stack 200' perpendicular to (and parallel to) faces 214a, 214b. These transparent cover plates 230 are also referred to as transparent spacers because they provide spacing between consecutive LOEs.

[0090] In embodiments where optical blocks 200' (optical blocks 200' having LOE 20 with spacers 230 between LOE 20) are provided, the thickness of the coating plate 302 used when forming optical blocks 300 should be adjusted to take into account the total thickness of optical blocks 200' and to ensure that the alignment of optical blocks 200' and 300 is such that each facet 38 is located in the plane at the midpoint between the main surfaces 24a and 24b of the associated LOE 20, so that optical blocks 200' and 300 are properly aligned and joined together. Additionally, as shown in FIG21, when a cutting step is performed to cut out a composite LOE using optical blocks 200' instead of optical blocks 200, the continuous cutting plane should pass through the continuous spacers 230 having one of the LOE 20 therebetween, and preferably approximately through the center of the spacers 230.

[0091] Figure 22 shows an example of a cut composite LOE 700 with two transparent cover plates 232, 234. Cover plates 232, 234 are formed from two of two cover plates 230 sliced ​​along the cutting plane 602 in a stack 200'. Cover plates 232, 234 are joined to LOE 20 such that face 231b of cover plate 232 is connected to face 24a of LOE 20, and face 231a of cover plate 234 is connected to face 24b of LOE 20. Face 233a of cover plate 232 (which is the opposite face to face 231b of cover plate 232) and face 233b of cover plate 234 (which is the opposite face to face 231a of cover plate 234) respectively form a portion of the main outer surfaces 714a, 714b of the composite LOE 700. Similar to the description above with reference to FIG15, the surfaces 714a and 714b of the composite LOE of FIG22 can then be polished to obtain a final composite LOE with the desired thickness and to ensure the parallelism between surfaces 714a and 714b.

[0092] While the embodiments described herein involve joining optical block 500 (or 500') to optical structure 400' such that the coupled reflector 42 is adapted to the spatial positioning of an image projector beneath the final composite LOE product, other embodiments are possible to adapt to different spatial positioning of the image projector. For example, optical block 500 may be inverted (e.g., by exchanging the positions of surfaces 514a, 514b) such that the reflective inner surface 42 is tilted upwards instead of downwards 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.

[0093] Although not shown in the figures, additional optical components, such as prisms, can be optically coupled or joined to optical block 500 (or 500') with or without inert blocks 800 and / or 900, prior to cutting out the composite LOE, to provide additional coupling geometry for the final composite LOE product. Alternatively, one or more additional optical components, such as prisms, can be optically coupled or joined to coupling reflector 42 at coupling region 750.

[0094] This disclosure has described various cutting steps in which optical material is cut along a cutting plane to produce various optical blocks and sub-components of optical blocks. It should be noted that in some embodiments, some or all of the surfaces produced by these cutting steps may be polished prior to the joining step. For example, the joining surfaces of optical blocks 100, 200, and 300 may be polished before joining optical blocks 100, 200, and 300 together. Additionally, the main surface of the LOE used to form optical block 200 may be polished before forming the stack of joined LOEs (optical block 200). Furthermore, the mating surface 404 and the joining surface of optical block 500 may be polished before joining optical blocks 400 and 500 together.

[0095] The alignment of the various blocks and structures described herein can be performed using any suitable optical alignment device / apparatus / tool ​​that performs appropriate optical alignment techniques / methods. Such a suitable optical alignment device / apparatus / tool ​​may include, for example, one or more computerized control devices, one or more computerized processing devices, and one or more optical subsystems having, for example, one or more light sources, one or more photodetectors / sensors, one or more optics (e.g., one or more lenses, folding optics, etc.), an automatic collimator, etc. Details of non-limiting examples of suitable optical alignment devices / apparatus / tools / methods that can be used to align the various blocks and structures described herein can be found in various publications of Lums Ltd. (Israel), including, for example, International Patent Application No. PCT / IL2021 / 051377 and International Patent Application No. PCT / IL2021 / 051378, which were not published prior to the filing date of this application and do not constitute prior art.

[0096] As will be understood by those skilled in the art, the cutting or slicing of the optical blocks and optical structures described herein can be performed using any suitable cutting equipment / apparatus / tool. As will be understood by those skilled in the art, the polishing of the faces and surfaces of the optical blocks and optical structures (including composite LOEs) described herein can be performed using any suitable polishing equipment / apparatus / tool.

[0097] While the embodiments described so far have involved joining two or three optical blocks, each carrying two or three sets of facets in a predetermined orientation, to accommodate light deflection along a predetermined direction, other embodiments are contemplated herein, in which one or more additional optical blocks carrying one or more additional sets of additional facets or optical retarder (e.g., one or more waveplates) in a predetermined orientation are joined to the aforementioned optical blocks. The scope of the invention should not be limited to any particular number of the aforementioned optical blocks.

[0098] Various embodiments of this disclosure have been described for illustrative purposes, but such description is not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments. The terminology used herein has been chosen to best describe the principles of the embodiments, their practical application, or technical improvements relative to technologies found in the market, or to enable those skilled in the art to understand the embodiments disclosed herein.

[0099] As used herein, unless the context clearly indicates otherwise, the singular forms “a,” “one,” and “the” include plural references.

[0100] The term "exemplary" is used herein to mean "serving as an example, instance, or illustration." Any implementation described as "exemplary" is not necessarily to be construed as preferred or advantageous over other implementations and / or excludes features incorporated from other implementations.

[0101] It should be understood that certain features of the invention described in the context of a single embodiment for clarity may also be provided in combination in a single embodiment. Conversely, various features of the invention described in the context of a single embodiment for brevity may also be provided individually or in any suitable sub-combination or as desired in any other described embodiment of the invention. Certain features described in the context of various embodiments should not be considered essential features of those embodiments unless the embodiment is inoperable without these elements.

[0102] As the appended claims are drafted without multiple references, this is done solely to accommodate the formal requirements of jurisdictions that do not permit such multiple references. It should be noted that all possible combinations of features implied by making the claims multiple-referenced are explicitly contemplated and should be considered part of this invention.

[0103] Although the invention has been described in conjunction with specific embodiments thereof, it will be apparent to those skilled in the art that many alternatives, modifications, and variations will be apparent. Therefore, it is intended to cover all such alternatives, modifications, and variations falling within the spirit and broad scope of the appended claims.

[0104] 1, 10, 20: Optical components 100, 300, 400, 500, 500': Optical blocks 102, 202, 302, 502: Coated panels 104, 106, 206, 304, 306, 402, 504, 602: Cutting planes 12a, 112a, 112b, 114a, 114b, 116a, 116b, 212a, 212b, 214a, 214b, 216a, 216b, 233a, 233b, 312a, 312b, 314a, 314b, 316a, 316b, 32a, 32b, 34a, 34b, 36a, 36b, 416a, 416b, 512a, 512a', 512b, 512b', 514a, 514a', 514b, 514b', 516a, 516a', 516b, 516b', 582a, 582b, 812a, 812b, 912a, 912b: Face 12b, 22a, 22b, 412a, 412b, 712a, 712b: First opposite position 14a, 204a, 204b, 714a, 714b: Parallel planes 14b, 24a, 24b, 584a, 584b, 594a, 594b, 814a, 814b, 914a, 914b: Second opposite 16a, 16b, 26a, 586a, 586b, 596a, 596b, 716a, 716b, 816a, 816b, 916a, 916b: Third opposite 18, 28, 38: small planes 200, 200': Optical blocks / stacks 20-1: First optical guide element 20-2: Second optical guide element 20-3: Third optical guide element 210: Arrangement 230: Cover plate / spacer plate 231a, 231b: External surfaces 232, 234: Cover plate 24a-2, 24a-3: First surface 24b-1, 24b-2: Second surface 30:Substrate 40: Interface 400', 505, 600: Optical structure 401: Triangular Prism Section 404: mating surface / face 414a, 414b: One side 42: Inner reflective surface / coupled reflector 50: Collimated image light 506, 508: Plane 52, 60, 62, 63, 64: Light rays 580, 590: Composite block / block 602-1: First cutting plane 602-2: Second cutting plane 700: Composite optical guide element 710: First LOE area 714a', 714b: Surface 720: Second LOE area 730: Area 750: Coupled Region 800, 900: Inert blocks / blocks

Claims

1. A method for manufacturing a composite light guide optical element (LOE), comprising: A stack is obtained having a first opposite face and a plurality of mirror surfaces (LOEs), each of the LOEs having a pair of main parallel surfaces and a first plurality of mutually parallel partially reflective inner surfaces inclined relative to the pair of main parallel surfaces; a first optical block is obtained having a second opposite face and a second plurality of mutually parallel partially reflective inner surfaces; the first optical block and the stack are joined together such that one of the first opposite faces is connected to one of the second opposite faces, and the first plurality of partially reflective inner surfaces are not parallel to the second plurality of partially reflective inner surfaces, thereby forming a second optical block; the second optical block is cut along a cutting plane passing through another of the second opposite faces, thereby forming a first optical structure having a mating surface at the cutting plane; a third optical block is obtained having a third opposite face and a plurality of mutually parallel reflective inner surfaces; the third optical block and the first optical structure are joined together such that one of the third opposite faces is connected to the mating surface, and the plurality of reflective inner surfaces are not parallel to the first plurality of partially reflective inner surfaces and the second plurality of partially reflective inner surfaces, thereby forming a second optical structure; And cut at least one composite LOE from the second optical structure by cutting the second optical structure through at least two cutting planes that are substantially parallel to the main parallel surface of the continuous LOE.

2. The method as described in claim 1, further comprising: For each cut composite LOE, the outer surface of the cut composite LOE, formed by cutting the second optical structure along two consecutive cutting planes in the cutting plane, is polished.

3. The method as described in request item 1, wherein, The first optical block has a pair of parallel surfaces, and wherein the second plurality of partially reflective inner surfaces are perpendicular to the pair of parallel surfaces of the first optical block.

4. The method as described in request item 1, wherein, The first optical block has a pair of parallel surfaces, and wherein the second plurality of partially reflective inner surfaces are inclined relative to the pair of parallel surfaces of the first optical block.

5. The method as described in request item 1, wherein, The first optical block has a third plurality of mutually parallel partially reflective inner surfaces that are not parallel to the first plurality of partially reflective inner surfaces and the second plurality of partially reflective inner surfaces.

6. The method as described in request item 5, wherein, The first optical block has: a first region, the first region including the second plurality of partially reflective inner surfaces; And a second region, the second region including the third plurality of partially reflective inner surfaces, wherein the first region and the second region of the first optical block are non-overlapping regions.

7. The method as described in request item 5, wherein, The third plurality of partially reflective inner surfaces are parallel to the main parallel surface of the LOE.

8. The method as described in request item 5, wherein, Each individual partial reflective inner surface in the third partial reflective inner surface lies in a plane approximately midway between a pair of principal parallel surfaces of the corresponding LOE.

9. The method as described in claim 5, wherein, 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.

10. The method as described in claim 5, wherein, 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.

11. The method as described in request item 1, wherein, The first optical block is formed by joining a first constitutive optical block and a second constitutive optical block, each having an opposite face, such that one of the opposite faces of the first constitutive optical block is connected to one of the opposite faces of the second constitutive optical block, wherein the first constitutive optical block includes a second plurality of partially reflective inner surfaces, and wherein the second constitutive optical block includes a third plurality of mutually parallel partially reflective inner surfaces that are not parallel to the first plurality of partially reflective inner surfaces and are not parallel to the second plurality of partially reflective inner surfaces.

12. The method as described in claim 1, wherein, The third optical block and the first optical structure are joined together such that substantially all of one of the faces of the third opposite side is connected to substantially all of the mating surface.

13. The method as described in request item 1, wherein, The third optical block and the first optical structure are joined together such that one of the faces of the third opposite side is connected to a portion of the mating surface.

14. The method as described in claim 1, wherein, The third optical block has an additional opposite face, and the method further includes: obtaining an inert block having a first opposite face and a second opposite face; joining the inert block and the third optical block together such that one face of the first opposite face of the inert block is connected to one face of the additional opposite face of the third optical block, thereby forming a composite block having a first face and a second face, the first face of the composite block being formed by one face of the third opposite face of the inert block and one face of the second opposite face, and the second face of the composite block being formed by the other face of the third opposite face of the inert block and one face of the second opposite face.

15. The method as described in claim 14, further comprising: Obtain a second inert block having one opposite face; and join the second inert block and the composite block together such that one face of the opposite face of the second inert block is connected to a second face of the composite block.

16. The method as described in claim 14, wherein, Joining the third optical block and the first optical structure together includes joining the composite block and the first optical structure together such that a first surface of the composite block is connected to the mating surface.

17. The method as described in claim 1, further comprising: Obtain an inert block having one opposite face; and join the inert block and the third optical block together such that one face of the opposite face of the inert block is connected to another face of the third opposite face of the third optical block.

18. The method described in any of claims 1 to 17, wherein, The stack is a combination of the LOE and a plurality of transparent spacers, wherein the LOE and the transparent spacers alternate along a length of the stack perpendicular to the main parallel surface of the LOE.

19. The method as described in claim 18, wherein, The at least two cutting planes are located in a continuous spacer plate having one of the LOEs therebetween.

20. A method for manufacturing a composite light guide optical element (LOE): obtaining a first optical block, the first optical block comprising: At least a first opposite side, a first region, the first region being formed by a stack of LOEs, each of the LOEs having a pair of main parallel surfaces and a set of a plurality of mutually parallel partially reflective inner surfaces, the plurality of mutually parallel partially reflective inner surfaces being located between the parallel surfaces and obliquely inclined relative to the parallel surfaces, such that the first region includes a first plurality of partially reflective inner surfaces, and a second region having a second plurality of mutually parallel partially reflective inner surfaces that are not parallel to the first plurality of partially reflective inner surfaces; The first optical block is cut along a cutting plane passing through one of the faces of the first opposite side, thereby forming a first optical structure having a mating surface at the cutting plane; a second optical block is obtained, the second optical block having a second opposite side and a plurality of mutually parallel reflective inner surfaces; the first optical structure and the second optical block are joined together such that one of the faces of the second opposite side is connected to the mating surface, and the plurality of reflective inner surfaces are not parallel to both the first plurality of partial reflective inner surfaces and the second plurality of partial reflective inner surfaces, thereby forming a second optical structure; And cut at least one composite LOE from the second optical structure by cutting the second optical structure through at least two cutting planes that are substantially parallel to the main parallel surface of the continuous LOE.

21. The method as described in claim 20, wherein, The first optical block further includes an additional pair of faces, wherein one of the main parallel surfaces of the LOE at the top of the stack forms part of one face of the additional pair of faces, and one of the main parallel surfaces of the LOE at the bottom of the stack forms part of the other face of the additional pair of faces.

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

23. The method as described in request item 22, wherein, 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.

24. The method as described in claim 22, wherein, 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.

25. The method as described in any of claims 20 to 24, wherein, The stack is a combination of the LOE and a plurality of transparent spacers, wherein the LOE and the transparent spacers alternate along a length of the stack perpendicular to the main parallel surface of the LOE.

26. The method as described in claim 25, wherein, The at least two cutting planes are located in a continuous spacer plate having one of the LOEs therebetween.

27. A method for manufacturing a composite light guide optical element (LOE): obtaining a first optical block having a first opposite face and a first plurality of mutually parallel partially reflective inner surfaces; obtaining a second optical block formed as a stack of LOEs and having a second opposite face, each of the LOEs having a pair of main parallel surfaces and a second plurality of mutually parallel partially reflective inner surfaces inclined relative to the pair of main parallel surfaces; obtaining a third optical block having a third opposite face and a third plurality of mutually parallel partially reflective inner surfaces; joining the first optical block and the third optical block together and joining the second optical block and the third optical block together to form a fourth optical block, wherein... The joining is such that: i) one of the faces of the first opposing face is connected to one of the faces of the third opposing face; ii) one of the faces of the second opposing face is connected to the other face of the third opposing face; iii) the third plurality of partially reflective inner surfaces are substantially parallel to the main parallel surface of the LOE; and iv) the first plurality of partially reflective inner surfaces, the second plurality of partially reflective inner surfaces, and the third plurality of partially reflective inner surfaces are not parallel to each other; the fourth optical block is cut along a cutting plane passing through the other face of the first opposing face, thereby forming a first optical structure having a mating surface at the cutting plane; A fifth optical block is obtained, the fifth optical block having a fourth opposite face and a plurality of mutually parallel reflective inner surfaces; the first optical structure and the fifth optical block are joined together to form a second optical structure, wherein the first optical structure and the fifth optical block are joined together such that one of the faces of the fourth opposite face is connected to the mating surface, and such that the plurality of reflective inner surfaces are not parallel to the first plurality of partial reflective inner surfaces, the second plurality of partial reflective inner surfaces and the third plurality of partial reflective inner surfaces; And cut at least one composite LOE from the second optical structure by cutting the second optical structure through at least two cutting planes that are substantially parallel to the main parallel surface of the continuous LOE.

28. The method as described in claim 27, wherein, The stack is a combination of the LOE and a plurality of transparent spacers, wherein the LOE and the transparent spacers alternate along a length of the stack perpendicular to the main parallel surface of the LOE.

29. The method as described in request item 28, wherein, The at least two cutting planes are located in a continuous spacer plate having one of the LOEs therebetween.

30. A method for manufacturing a composite light guide optical element (LOE): obtaining a first optical block having a first opposite face and a first plurality of mutually parallel partially reflective inner surfaces; obtaining a second optical block formed as a stack of LOEs and having a second opposite face, each of the LOEs having a pair of main parallel surfaces and a second plurality of mutually parallel partially reflective inner surfaces inclined relative to the pair of main parallel surfaces; obtaining a third optical block having a third opposite face and a third plurality of mutually parallel partially reflective inner surfaces; joining the first optical block and the third optical block together and joining the first optical block and the second optical block together to form a fourth optical block, wherein... The joining is such that: i) one of the third opposite faces is connected to one of the first opposite faces; ii) one of the second opposite faces is connected to the other of the first opposite faces; iii) the third plurality of partially reflective inner surfaces are substantially parallel to the main parallel surface of the LOE; and iv) the first plurality of partially reflective inner surfaces, the second plurality of partially reflective inner surfaces, and the third plurality of partially reflective inner surfaces are not parallel to each other; the fourth optical block is cut along a cutting plane passing through the other of the third opposite faces to form a first optical structure having mating surfaces at the cutting plane; a fifth optical block is obtained, the fifth optical block having a fourth opposite face and a plurality of mutually parallel reflective inner surfaces; The first optical structure and the fifth optical block are joined together to form a second optical structure, wherein the first optical structure and the fifth optical block are joined together such that one of the fourth opposing surfaces is connected to the mating surface, and such that the plurality of reflective inner surfaces are not parallel to the first plurality of partially reflective inner surfaces, the second plurality of partially reflective inner surfaces and the third plurality of partially reflective inner surfaces, thereby forming the second optical structure; and at least one composite LOE is cut from the second optical structure by cutting it through at least two cutting planes that are substantially parallel to the main parallel surfaces of the continuous LOE.

31. The method as described in claim 30, wherein, The stack is a combination of the LOE and a plurality of transparent spacers, wherein the LOE and the transparent spacers alternate along a length of the stack perpendicular to the main parallel surface of the LOE.

32. The method as described in claim 31, wherein, The at least two cutting planes are located in a continuous spacer plate having one of the LOEs therebetween.

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