Manufacturing method of optical aperture multiplier with rectangular waveguide

Abstract

The present disclosure relates to a method of manufacturing an optical aperture multiplier having a rectangular waveguide. The method comprises: obtaining a bonded stack of light guide optical elements (LOEs), each LOE of the bonded stack having a pair of main parallel surfaces and a first plurality of mutually parallel partially reflective inner surfaces inclined to the pair of main parallel surfaces; obtaining a sheet having: a plurality of outer surfaces including a pair of parallel surfaces, and a second plurality of mutually parallel partially reflective inner surfaces inclined to the pair of parallel surfaces; optically coupling the sheet with the adhesive stack such that one of the pair of parallel planes is in facing relationship with the coupling surface of the adhesive stack, and such that the pair of parallel planes is perpendicular to the pair of main parallel surfaces of each of the LOEs of the adhesive stack, thereby forming an optical structure; and cutting out at least one optical aperture multiplier from the optical structure via cutting the optical structure by at least two cutting planes substantially parallel to the main parallel surface of the continuous LOE and perpendicular to the coupling surface of the adhesive stack.

Description

[0001] This application is a divisional application of an invention patent application with an application date of May 12, 2022, application number 202280040294.3 (international stage application number PCT / IL2022 / 050500), and invention name “Manufacturing method of an optical aperture multiplier with a rectangular waveguide”.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to U.S. Provisional Patent Application No. 63 / 197,452, filed on June 7, 2021, the entire disclosure of which is incorporated herein by reference. Technical Field

[0004] The present invention relates to an optical aperture multiplier, and in particular to an optical aperture multiplier including a rectangular optical waveguide optically coupled to a thin-plate type optical waveguide. Background Art

[0005] Optical arrangements for near eye displays or heads-up displays require large apertures to cover the area where the observer's eyes are located. Optical devices that provide two-dimensional optical aperture expansion (or multiplication) have been described in various publications by Lumus Ltd (Israel). In a particular set of such optical devices, the two-dimensional aperture expansion is achieved by two optical waveguides. A first optical waveguide has two pairs of parallel faces forming a rectangular cross-section, and a second optical waveguide in the form of a thin plate is optically coupled to the first (rectangular) waveguide and has a pair of parallel main external faces. The two waveguides cooperate to expand the aperture of the injected image in two dimensions, wherein the first waveguide expands the aperture in a first dimension, and the second waveguide expands the aperture in a second dimension and couples out an image of the expanded aperture to be viewed by the viewer's eyes.

[0006] In order to maintain image quality, the parallelism of the waveguide faces and the perpendicularity between the two faces of the rectangular waveguide are strictly required, because deviations from parallelism and / or perpendicularity will reduce image quality. This requirement for parallelism and perpendicularity imposes strict manufacturing requirements, making the manufacturing process more expensive. Summary of the invention

[0007] Embodiments of the present invention provide a method / process for manufacturing an optical aperture multiplier having a rectangular waveguide and an optical structure that is an intermediate work product in such a method / process.

[0008] According to the teaching of the embodiments of the present invention, a method for manufacturing an optical aperture multiplier is provided. The method comprises: obtaining a sheet having a plurality of external surfaces including a pair of parallel surfaces and a first plurality of mutually parallel partially reflective internal surfaces inclined to the pair of parallel surfaces; obtaining a first optical structure having a plurality of external surfaces including a planar coupling surface and a second plurality of mutually parallel partially reflective internal surfaces inclined to the coupling surface; optically coupling the sheet with the first optical structure so that one of the pair of parallel surfaces is in a facing relationship with the coupling surface, thereby forming a second optical structure; and cutting the second optical structure through at least two cutting planes perpendicular to the coupling surface, thereby cutting out at least one optical aperture multiplier from the second optical structure.

[0009] Optionally, the first optical structure is produced by a bonded stack of coated transparent plates.

[0010] Optionally, the bonded stack has a pair of faces, and the first optical structure is produced from the bonded stack by cutting the bonded stack along a cutting plane that is angled relative to at least one of the pair of faces of the bonded stack.

[0011] Optionally, the first optical structure is produced from the bonded stack by further polishing or slicing at the location of the cleavage plane to form a coupling surface.

[0012] Optionally, the first optical structure is formed as a bonded stack of light guiding optical elements (LOEs), each LOE of the bonded stack having a pair of major parallel surfaces and a subset of a second plurality of mutually parallel partially reflective inner surfaces inclined to the pair of major parallel surfaces.

[0013] Optionally, at least two cutting planes are substantially parallel to major parallel surfaces of the continuous LOE.

[0014] Optionally, the bonded stack comprises a plurality of transparent spacers, and the LOEs and transparent spacers alternate along the length of the bonded stack perpendicular to the major parallel surfaces of the LOEs.

[0015] Optionally, at least two cutting planes are located in consecutive partitions between which one of the LOEs is sandwiched.

[0016] Optionally, the method also includes: obtaining a third optical structure, the third optical structure having a plurality of external surfaces including a coupling surface and a plurality of mutually parallel internal surfaces inclined to the coupling surface; and optically coupling the third optical structure with the sheet before cutting out at least one optical aperture multiplier, so that the coupling surface of the third optical structure is in a facing relationship with one of the external surfaces of the sheet.

[0017] According to an embodiment of the teachings of the present invention, there is also provided a method for manufacturing an optical aperture multiplier. The method comprises: obtaining a sheet having a plurality of external faces including a pair of parallel faces and a plurality of mutually parallel partially reflective internal surfaces inclined to the pair of parallel faces; generating a first optical structure having a plurality of external surfaces by a bonded stack of coated transparent plates, the plurality of external surfaces including a coupling surface inclined to a major surface of the coated transparent plate; optically coupling the sheet with the first optical structure so that one of the pair of parallel faces is in a facing relationship with the coupling surface, thereby forming a second optical structure; and cutting the second optical structure by at least two cutting planes perpendicular to the coupling surface, thereby cutting out at least one optical aperture multiplier from the second optical structure.

[0018] Optionally, the bonded stack has a pair of faces, and generating the first optical structure from the bonded stack comprises cutting the bonded stack along a cutting plane that is angled relative to at least one of the pair of faces of the bonded stack.

[0019] Optionally, generating the first optical structure from the bonded stack further comprises: polishing at the location of the cutting plane to form a coupling surface.

[0020] According to an embodiment of the teachings of the present invention, a method for manufacturing an optical aperture multiplier is also provided. The method includes: obtaining a bonded stack of light-guiding optical elements (LOEs), each LOE of the bonded stack having a pair of main parallel surfaces and a first plurality of mutually parallel partially reflective inner surfaces inclined to the pair of main parallel surfaces; obtaining a sheet having a plurality of external surfaces including a pair of parallel surfaces and a second plurality of mutually parallel partially reflective inner surfaces inclined to the pair of parallel surfaces; optically coupling the sheet to the bonded stack so that one of the pair of parallel surfaces is in a facing relationship with the coupling surface of the bonded stack, and so that the pair of parallel surfaces is perpendicular to the pair of main parallel surfaces of each LOE of the bonded stack, thereby forming an optical structure; and cutting the optical structure through at least two cutting planes substantially parallel to the main parallel surfaces of consecutive LOEs and perpendicular to the coupling surface of the bonded stack, cutting out at least one optical aperture multiplier from the optical structure.

[0021] Optionally, the bonded stack comprises a plurality of transparent spacers, and the LOEs and transparent spacers alternate along the length of the bonded stack perpendicular to the major parallel surfaces of the LOEs.

[0022] Optionally, at least two cutting planes are located in consecutive partitions between which one of the LOEs is sandwiched.

[0023] Optionally, any of the methods according to the embodiments of the present invention further comprises: optically coupling the cover plate to the sheet at one or more of the pair of parallel faces.

[0024] Optionally, the cover plate comprises a reflective coating.

[0025] Optionally, optically coupling the cover plate to the sheet comprises bonding the cover plate to one or more of the pair of parallel faces.

[0026] Optionally, bonding is performed using an optical glue having a refractive index lower than that of the material used to produce the sheet.

[0027] Optionally, the cover plate is optically coupled to the sheet at one of the parallel planes in facing relationship with the coupling surface, and the cover plate has polarization management properties.

[0028] Optionally, the cover plate comprises at least one of a wave plate or a polariser.

[0029] According to an embodiment of the teachings of the present invention, there is also provided an optical structure which is an intermediate work product of an optical aperture multiplier manufacturing process. The optical structure comprises: a first portion, the first portion comprising a plurality of external faces including a pair of parallel faces and a first plurality of mutually parallel partially reflective internal surfaces inclined to the pair of parallel faces; and a second portion, the second portion comprising a plurality of external surfaces including a coupling surface and a second plurality of mutually parallel partially reflective internal surfaces inclined to the coupling surface, the second portion being optically coupled to the first portion such that one of the pair of parallel faces is in a facing relationship with the coupling surface, and such that at least one optical aperture multiplier is produced when the optical structure is sliced ​​by at least two substantially parallel cutting planes passing through the first portion and the second portion and perpendicular to the coupling surface.

[0030] Optionally, the second part is formed by a bonded stack of coated transparent sheets.

[0031] Optionally, the second portion is formed as a bonded stack of light-guiding optical elements (LOEs), each LOE of the bonded stack having a pair of major parallel surfaces and a subset of a second plurality of mutually parallel partially reflective inner surfaces inclined to the pair of major parallel surfaces.

[0032] Optionally, the bonded stack comprises a plurality of transparent spacers, and the LOEs and transparent spacers alternate along the length of the bonded stack perpendicular to the major parallel surfaces of the LOEs.

[0033] Optionally, the optical structure also includes: a third part, the third part having multiple external surfaces including a coupling surface and multiple mutually parallel internal surfaces inclined to the coupling surface, the third part is optically coupled to the first part so that the coupling surface of the third part is in a facing relationship with one of the external surfaces of the first part.

[0034] According to an embodiment of the teachings of the present invention, there is also provided an optical structure which is an intermediate work product of an optical aperture multiplier manufacturing process. The optical structure comprises: a first portion having a plurality of external faces including a pair of parallel faces and a plurality of mutually parallel partially reflective internal surfaces inclined to the first pair of parallel faces; and a second portion formed by a bonded stack of coated transparent plates, the second portion having a plurality of external surfaces including a coupling surface inclined to a major surface of the coated transparent plate, the first portion being optically coupled to the second portion such that one face of the pair of parallel faces is in a facing relationship with the coupling surface, and such that at least one optical aperture multiplier is produced when the optical structure is sliced ​​by at least two substantially parallel cutting planes passing through the first portion and the second portion and perpendicular to the coupling surface.

[0035] Optionally, the bonded stack has a pair of faces, and the second portion is formed by cutting the bonded stack along a cutting plane that is angled relative to at least one of the pair of faces of the bonded stack.

[0036] Optionally, the coupling surface is formed by polishing the second portion at the location of the cutting plane.

[0037] According to an embodiment of the teachings of the present invention, an optical structure is also provided, which is an intermediate work product of an optical aperture multiplier manufacturing process. The optical structure includes: a second part, the second part includes a plurality of external faces including a pair of parallel faces and a second plurality of mutually parallel partially reflective internal surfaces inclined to the pair of parallel faces; and a second part, the second part includes a bonded stack of light-guiding optical elements (LOEs), each LOE of the bonded stack having a pair of main parallel surfaces and a first plurality of mutually parallel partially reflective internal surfaces inclined to the pair of main parallel surfaces, the first part is optically coupled to the second part so that one of the pair of parallel faces is in a facing relationship with a coupling surface (322) of the second part, and so that the pair of parallel faces is perpendicular to the pair of main parallel surfaces of each of the LOEs of the bonded stack.

[0038] Optionally, the bonded stack comprises a plurality of transparent spacers, and the LOEs and transparent spacers alternate along the length of the bonded stack perpendicular to the major parallel surfaces of the LOEs.

[0039] Optionally, any one of the intermediate work products according to the embodiments of the present invention further comprises: a cover plate optically coupled to the first portion at one or more of the pair of parallel surfaces.

[0040] Optionally, the cover plate comprises a reflective coating.

[0041] Optionally, the cover plate is optically coupled to the first portion by bonding the cover plate to one of the pair of parallel faces.

[0042] Optionally, the bonding is performed using an optical glue having a refractive index lower than the refractive index of the material used to produce the first part.

[0043] Optionally, the cover plate is optically coupled to the first portion at one of the pair of parallel faces in facing relationship with the coupling surface, and the cover plate has polarization management properties.

[0044] Optionally, the cover plate comprises at least one of a wave plate or a polariser.

[0045] Unless otherwise defined herein, all technical terms and / or scientific terms used herein have the same meanings as those of ordinary skill in the art to which the present invention belongs. Although methods and materials similar or equivalent to these methods and materials described herein can be used in the practice or testing of embodiments of the present invention, exemplary methods and / or materials are described as follows. In the event of a conflict, the patent specification (including definitions) shall prevail. In addition, materials, methods and examples are only illustrative and are not intended to necessarily limit. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Some embodiments of the present invention are described herein by way of example only with reference to the accompanying drawings. By referring specifically in detail to the accompanying drawings, it is emphasized that the details shown are by way of example and for the purpose of illustrative discussion of embodiments of the present invention. In this regard, the description in conjunction with the accompanying drawings makes it clear to those skilled in the art how embodiments of the present invention may be practiced.

[0047] Attention is now directed to the accompanying drawings, in which like reference numerals or characters indicate corresponding or identical parts. In the accompanying drawings:

[0048] Figure 1A and Figure 1B are schematic side and front views, respectively, of an optical aperture multiplier having a first rectangular optical waveguide having a plurality of partially reflective interior surfaces optically coupled to a second thin-plate type optical waveguide having a plurality of partially reflective interior surfaces that may be fabricated using a fabrication process according to the teachings of an embodiment of the present invention;

[0049] FIG. 2A to FIG. 2I is a diagram showing an optical aperture multiplier according to a first group of embodiments of the present invention, for example Figure 1A and Figure 1B A schematic isometric view of a sequence of steps used in the fabrication of an optical aperture multiplier;

[0050] Figure 3A and Figure 3B It is a diagram showing a method for manufacturing a FIG. 2A to FIG. 2I Schematic isometric view of a sequence of steps in a sheet optical structure used in a process;

[0051] Figure 4 is a schematic isometric view illustrating another technique that may be used to manufacture sheet optical structures according to an embodiment of the present invention;

[0052] FIG. 5A to FIG. 5D is a schematic isometric view showing a sequence of steps used in the manufacture of an optical aperture multiplier according to a second set of embodiments of the present invention;

[0053] Fig. 6A is a schematic plan view of an optical structure according to an embodiment of the present invention, from which a plurality of optical coupling-in configurations can be extracted and which can be used in a manufacturing process of an optical aperture multiplier;

[0054] FIG. 6B to FIG. 6D Respectively and FIG. 5A to FIG. 5D The process steps produce another optical structure that is optically coupled to Fig. 6A Schematic plan view, front view and isometric view of the optical structure of; and

[0055] Fig. 6E is a schematic isometric view of an optical aperture multiplier that may be produced using a fabrication process according to an embodiment of the present invention. DETAILED DESCRIPTION

[0056] Embodiments of the present invention provide a method / process for manufacturing an optical aperture multiplier having a rectangular waveguide and an optical structure that is an intermediate work product in such a method / process.

[0057] The principles and operations of the methods and intermediate work products according to the present invention may be better understood with reference to the accompanying drawings of the specification. The drawings have an xyz coordinate system that is arbitrarily labeled but consistent between the drawings. The xyz coordinate system is used herein to better explain the disclosed embodiments by providing a common reference system among the drawings.

[0058] Before explaining at least one embodiment of the present invention in detail, it should be understood that the application of the present 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 shown in the drawings and / or examples. The present invention can have other embodiments or be practiced or performed in various ways. First, in this document, reference is made to directions such as top and bottom, upper and lower, front and rear. These directional references are exemplary only and are only used for ease of presentation and refer to arbitrary orientations as shown in the drawings. The final optical device can be deployed in any desired orientation.

[0059] By way of introduction, commonly owned U.S. Patent No. 10,133,070 describes Figure 1A and Figure 1B Various embodiments of an optical aperture multiplier 1 are generally shown in , which is incorporated herein by reference in its entirety. The optical aperture multiplier 1 is particularly suitable for use as part of a near-eye display or a head-up display for augmented reality applications. In general, the optical aperture multiplier 1 (also referred to as an "optical device") includes a first optical waveguide 10 having an elongated direction (arbitrarily illustrated herein as corresponding to the "x-axis"). The first optical waveguide 10 is formed of a light-transmitting material and has a first pair of parallel faces 12a, 12b and a second pair of parallel faces 14a, 14b forming a rectangular cross-section (i.e., the first and second pairs of faces are perpendicular). The first optical waveguide 10 also has an additional pair of faces 16a, 16b (which may or may not be parallel faces). In certain embodiments where the faces 16a, 16b are parallel faces, the faces 16a, 16b may be perpendicular to the first and second pairs of faces 12a, 12b, 14a, 14b. The first optical waveguide 10 has a plurality of mutually parallel partially reflective inner surfaces (also referred to as “facets”) 40, which at least partially traverse the first optical waveguide 10 and are obliquely inclined to the elongation direction of the first optical waveguide 10 (i.e., the facets 40 are inclined to the surfaces 12a, 12b).

[0060] In this document, the terms "face", "external face" and "external surface" may be used interchangeably. As will become apparent, some of these faces are primary faces (also referred to as "primary external faces" or "primary external surfaces").

[0061] The optical aperture multiplier 1 also includes a second optical waveguide 20 optically coupled to the first optical waveguide 10, the second optical waveguide having a third pair of parallel faces 22a, 22b. Here again, a plurality of mutually parallel partially reflective internal surfaces ("facets") 45 at least partially traverse the second optical waveguide 20 and are obliquely inclined to the faces 22a, 22b. The second optical waveguide 20 also has two additional pairs of pairs of faces 24a, 24a, 26a, 26b, each of which is not parallel to the faces 22a, 22b, and each of which may or may not be a pair of parallel faces. In some embodiments, the pairs of faces 22a, 22b, 24a, 24b, 26a, 26b are perpendicular to each other. In certain embodiments, facet 45 is also obliquely inclined to one or both of faces 24a, 24b, however, as will be discussed, in other embodiments, facet 45 may be parallel to one or both of faces 24a, 24b and / or perpendicular to one or both of faces 26a, 26b.

[0062] The second optical waveguide 20 is also formed of a light-transmitting material (light-transmitting substrate), and is preferably formed of the same material as that used to form the first optical waveguide 10 (so that the two optical waveguides 10, 20 have the same refractive index), but forms a thin-plate type waveguide in which the distance between the opposing faces 24a, 24b, 26a, 26b is at least one order of magnitude greater than the distance between the faces 22a, 22b.

[0063] The optical coupling between the optical waveguides 10, 20 (at the interface between the faces 12b, 24a) and the deployment and construction of the partially reflective surfaces 40, 45 are such that, when image light 30 (also referred to as a "light beam" or "beam") corresponding to a collimated image (generated by an optical image generator not shown) is coupled (injected) into the first optical waveguide 10 in an initial propagation direction at a coupling angle inclined to both the first pair of parallel faces 12a, 12b and the second pair of parallel faces 14a, 14b, the image advances along the first optical waveguide 10 by quadruple internal reflection (images a1, a2, a3, a4), wherein a certain proportion of the intensity of the image is reflected at the partially reflective surface 40 to be coupled into the second optical waveguide 20, and then the image is propagated by double internal reflection (images b1, b1) within the second optical waveguide 20, wherein a certain proportion of the intensity of the image is reflected (deflected) at the partially reflective surface 45 to be directed outward from one of the parallel faces 22b as a visible image c seen by the observer's eye 47.

[0064] The first optical waveguide 10 is also referred to as a two-dimensional (2D) waveguide in the sense that it guides the injected image in two dimensions by reflection between two sets of parallel faces (12a, 12b, 14a, 14b), while the second optical waveguide 20 is also referred to as a one-dimensional (1D) waveguide in the sense that it guides the injected image in only one dimension between a pair of parallel faces (22a, 22b). The second optical waveguide 20 is also interchangeably referred to herein as a light-guide optical element (LOE) or a 1D LOE.

[0065] U.S. Patent No. 10,133,070 also describes a manufacturing process for an optical aperture multiplier 1. These processes rely on manufacturing two optical waveguides 10, 20 separately and then coupling the two independent waveguides 10, 20 together to produce an independent optical aperture multiplier. However, this manufacturing process makes the large-scale production of optical aperture multipliers more challenging.

[0066] Embodiments of the present invention provide processes that can be used to manufacture an optical aperture multiplier 1. As will become apparent from the following description, the manufacturing process according to embodiments of the present invention enables large-scale production of optical aperture multipliers that are particularly suitable for use as part of a near-eye display or head-up display for augmented reality applications, while maintaining perpendicularity and parallelism on large optical surfaces, thereby enabling tighter manufacturing tolerances.

[0067] In the first group of embodiments, as will be referred to FIG. 2A to FIG. 2I As described, a bonded stack of coated transparent plates is obtained. The coated surface of the transparent plate forms a plurality of mutually parallel partially reflective inner surfaces (which ultimately form facets 45). The bonded stack is cut along a cutting plane to form an optical structure having a plurality of outer surfaces, the plurality of outer surfaces including a coupling surface inclined to the main surface of the coated transparent plate (i.e., the coupling surface is inclined to the partially reflective inner surface 45). A sheet (which is an optical structure itself) having a pair of external parallel faces and a plurality of mutually parallel partially reflective inner surfaces inclined to the pair of parallel faces (which ultimately form facets 40) is optically coupled with the optical structure at the coupling surface to form a second optical structure. The second optical structure is then sliced ​​along two or more parallel cutting planes perpendicular to the coupling surfaces to extract one or more optical aperture multipliers 1.

[0068] In the second group of embodiments, as will be referred to Figures 5A to 5D As described, a bonded stack of LOE 20 is obtained. This bonded stack of LOEs constitutes a first optical structure having a coupling surface that is inclined to the facet 45 of LOE 20 (and also perpendicular to the faces 22a, 22b of LOE 20). Similar to the first set of embodiments, a sheet having a pair of external parallel faces and a plurality of mutually parallel partially reflective internal surfaces inclined to the pair of parallel faces (which ultimately form facets 40) is optically coupled to the optical structure at the coupling surface to form a second optical structure. This second optical structure is then sliced ​​along two or more parallel cutting planes perpendicular to the coupling surface to extract one or more optical aperture multipliers 1. In this case, the cutting planes are parallel to the faces 22a, 22b of LOE 20, and in some cases may be approximately located at the faces 22a, 22b of LOE 20. As will be discussed, in certain embodiments, the bonded stack of LOE 20 may include a plurality of transparent spacers, wherein the LOE 20 and the spacers alternate along the length of the bonded stack that is perpendicular to the faces 22a, 22b of LOE 20. In such an embodiment, successive cutting planes are located in successive partitions with a LOE sandwiched therebetween.

[0069] As will become apparent from the subsequent description, both sets of embodiments employ the following steps, which generally include: 1) obtaining a sheet having a pair of external parallel faces and a plurality of internal surfaces inclined to the pair of parallel faces (which ultimately form facets 40); 2) obtaining a first optical structure having: i) a plurality of external surfaces including a coupling surface, and ii) a coupling surface inclined to the coupling surface; 3) forming a second optical structure by optically coupling the sheet to the optical structure such that one of the pair of parallel faces of the sheet is in a facing relationship with the coupling surface of the first optical structure; and 4) cutting the second optical structure through at least two cutting planes perpendicular to the coupling surface.

[0070] Now go to FIG. 2A to FIG. 2I , showing the steps of a preferred method (process) that can be used to manufacture an optical aperture multiplier such as optical aperture multiplier 1 according to the first group of embodiments of the present invention.

[0071] like Figure 2A As shown, a sheet 110 having a plurality of external faces including a pair of parallel faces 112a, 112b is obtained. The sheet 110 also has a plurality of mutually parallel partially reflective inner surfaces (facets) 40 inclined to the faces 112a, 112b. In addition, the sheet 110 has another pair of opposite faces 114a, 114b, which in some embodiments are also a pair of parallel faces that together with the faces 112a, 112b form a rectangular cross section. The sheet 110 may also have an additional pair of opposite faces 116a, 116b, which may or may not be parallel faces. In some embodiments, the three opposite faces 112a, 112b, 114a, 114b, 116a, 116b of the sheet 110 are mutually orthogonal.

[0072] Incidentally, the sheet 110 itself is an optical structure, and the term "sheet" is used herein as a naming convention to refer to the preferred method in which the optical structure 110 can be produced. In general, the sheet 110 can be obtained in a variety of ways, usually by "cutting" the sheet out of an optical structure formed by stacking plates. In one exemplary method, as shown in FIG. Figure 3A As shown, a plurality of coated transparent plates 102 having parallel upper surfaces 103a and lower surfaces 103b are obtained. The coating of the coated transparent plates is a selective reflective coating that provides partial reflectivity of the facets 40 (ie, makes the facets 40 partially reflective). Figure 3B As shown, the panels 102 are aligned and arranged in a staggered stack and bonded together to form a bonded stack 101. The bonding is such that for each panel 102, the lower surface 103b of the panel engages the upper surface 103a of the adjacent panel. In this document, the term "bonded" or "bonding" should be understood to mean attached or attached with optical glue or glue or any other suitable adhesive.

[0073] Then, along at least two parallel cutting planes inclined to the surfaces 103a, 103b (given by Figure 3B The bonded stack 101 is cut (indicated by the dashed lines 104 in the figure) to produce one or more sheets 110. The cutting planes 104 are preferably spaced apart at predetermined and uniform intervals. As a result of cutting along the cutting planes 104, each sheet 110 has a pair of parallel faces 112a, 112b and a plurality of mutually parallel partially reflective inner surfaces (facets) 40 inclined to the faces 112a, 112b. Note that the cutting planes 104 define the inclination angles of the facets 40 in the final rectangular waveguide 10. In the illustrated embodiment, the planes 104 are perpendicular to the side surfaces of the plate 102 (in the figure, the side surfaces are in a plane parallel to the xy plane). However, in some embodiments, the cutting planes 104 may have an inclination angle relative to the side surfaces (xy plane) so that the facets 40 are also inclined to the parallel faces 114a, 114b. The stack 101 can be further cut along one or more pairs of cutting planes (preferably but not necessarily pairs of parallel cutting planes) that are preferably but not necessarily orthogonal to the plane 104 to set one or more pairs of other pairs of faces 114a, 114b, 116a, 116b of the sheet 110.

[0074] Figure 4 Another exemplary method for obtaining a sheet 110 is shown. Here, the plates 102 are aligned and bonded to form a non-staggered bonded stack 109 (i.e., a rectangular or approximately rectangular block), and then the non-staggered bonded stack 109 is cut along parallel cutting planes 104' (which are inclined to the surfaces 103a, 103b) to extract one or more sheets 110. In the embodiment shown, the plane 104' is perpendicular to the side surface of the plate 102 (in the figure, the side surface is in a plane parallel to the xy plane). However, in some embodiments, the cutting plane 104' can have an inclined angle relative to the side surface (xy plane) so that the facet 40 is also inclined to the parallel planes 114a, 114b. Similarly, similar to stack 101, stack 109 can be further cut along one or more pairs of cutting planes (preferably but not necessarily pairs of parallel cutting planes) that are preferably but not necessarily orthogonal to plane 104' to set one or more pairs of other pairs of faces 114a, 114b, 116a, 116b of sheet 110.

[0075] Now return to FIG. 2A to FIG. 2I In certain embodiments, Figure 2B and Figure 2C As shown, the plate 120a can be aligned with the face 112a of the sheet 110 and applied to the face 112a. Alternatively or additionally, also as Figure 2B and 2CAs shown, plate 120b can be aligned with face 112b of sheet 110 and applied to face 112b. Applying plates 120a, 120b to faces 112a, 112b constitutes an optical coupling between plates 120a, 120b and sheet 110 at faces 112a, 112b. In some embodiments, the optical coupling is achieved by bonding, whereby plate 120a is bonded to sheet 110 such that the plate is bonded to face 112a, and / or plate 120b is bonded to sheet 110 such that plate 120b is bonded to face 112b.

[0076] Both cover plates 120a, 120b can provide mechanical protection for sheet 110, for example, by preventing defects that may be formed on sheet 110 during polishing of either or both of faces 112a, 112b. In addition to providing mechanical protection, cover plates 120a, 120b can also provide optical functions by applying various materials or coatings thereon. In one example, plate 120a (and / or plate 120b) includes a reflective coating that prevents light from an external (real world) scene from entering waveguide 10, while also maintaining conditions for internal reflection at face 12a (and / or face 12b) of waveguide 10. In another example, the optical glue used to bond the plate 120a (and / or plate 120b) to the sheet 110 has a low refractive index (lower than the refractive index of the material constituting the sheet 110, i.e., lower than the refractive index of the plate 102) so as to maintain the condition of total internal reflection at the face 12a (and / or face 12b) of the waveguide 10 despite the accumulation of dust, debris or other particles at the interface between the plates 120a, 120b and the sheet 110. An optical glue having a refractive index of, for example, about 1.35 may be particularly suitable for bonding the plates 120a, 120b to the sheet 110.

[0077] In some embodiments, one of the plates 120a or 120b may have polarization management properties (i.e., the plate 120b may be a polarization management plate) to control or modify the polarization of light to be transmitted from the waveguide 10 into the waveguide 20. The polarization management plate may be implemented as, for example, a wave plate (e.g., a half-wave plate) and / or a polarizer.

[0078] Note that instead of optically coupling the plates 120a, 120b having the above-described materials or coatings, the materials or coatings may be applied directly to either or both of the faces 112a, 112b. For example, a reflective coating may be applied directly to either or both of the faces 112a, 112b to prevent unwanted reflections and maintain internal reflection conditions at the faces 112a and / or 112b.

[0079] Now refer to Figure 2D, a plurality of coated transparent plates 202 having parallel upper major surfaces 203a and lower major surfaces 203b are obtained. The coating of the coated transparent plates is a selective reflection coating which provides partial reflectivity of the facets 45 of the optical waveguide 20 (ie, makes the facets 45 partially reflective).

[0080] like Figure 2E As shown, the plates 202 are aligned and arranged in a stack (preferably a non-staggered stack) and bonded together to form a bonded stack 210 of parallel plates 202. The bonding is such that for each plate 202, the lower surface 203b of the plate is engaged with the upper surface 203a of the adjacent plate. The bonded stack 210 has three pairs of faces 212a, 212b, 214a, 214b, 216a, 216b, each pair of which may or may not be a pair of parallel faces. The faces 212a, 212b are preferably parallel faces, and therefore preferably parallel to the surfaces 203a, 203b of the plates 202. In addition, the surface 203a of the top plate in the bonded stack 210 forms the face 212a, and the surface 203b of the bottom plate in the bonded stack 210 forms the face 212b.

[0081] In some embodiments, the pairs of faces 212a, 212b and 214a, 214b are two pairs of parallel faces and together form a rectangular cross section. In some embodiments, each pair of pairs of faces of the bonded stack 210 is a pair of parallel faces, and the three pairs of faces 212a, 212b, 214a, 214b, 216a, 216b are mutually orthogonal. It should be noted that generally if any pair of faces of the bonded stack 210 is not initially a pair of parallel faces, any one or both of the faces of the pair may be polished to achieve parallelism between the pairs.

[0082] It should be noted that Figure 2EThe exemplary stack 210 in the non-limiting embodiment shown in is a non-staggered stack, whereby the various side surfaces of the plates 202 (i.e., the surfaces of the plates 202 other than the upper surface 203a and the lower surface 203b) are aligned and coplanar to form substantially flat and smooth faces 214a, 214b, 216a, 216b. For example, the front side surfaces of the plates 202 in a plane parallel to the yz plane are aligned to form the face 214a, and the rear side surfaces (not shown) of the plates 202 in a plane parallel to the yz plane are aligned to form the face 214b, whereby each of the faces 214a, 214b is a substantially flat and smooth surface. Similar principles apply to the side surfaces forming the faces 216a, 216b. However, in certain embodiments, such as embodiments in which the stack 210 is formed as a staggered stack, one or more of the faces 214a, 214b, 216a, 216b may include a step or variation in the depth of the side surfaces of the constituent plates 202 that form the stack 210 (i.e., set downward or stepped upward). Therefore, the term "face" used herein to describe and claim the faces 214a, 214b, 216a, 216b generally refers to an apparent face in a plane parallel to the surface of the plate 202 that forms the face. For example, the face 214a refers to an apparent face in a plane parallel to the yz plane, even though there is a variation in the depth of the front side surface of the plate 202. In the case where the stack 210 is a non-staggered stack and the plates 202 are perfectly aligned (e.g., as shown in FIG. 2A ), the depth of the side surfaces of the constituent plates 202 may vary. Figure 2E In the embodiment shown in ), the apparent surface and the actual surface are the same.

[0083] Now go to Figure 2F and Figure 2G , optical structure 220( Figure 2G ) is produced by the bonded stack 210. The optical structure 220 has a plurality of outer surfaces (multiple faces) including planar coupling surfaces 222 (also referred to as "coupling faces", "interfacing surfaces", "interface surfaces" or simply "faces" 222) which are inclined to the major surfaces 203a, 203b of the coated transparent plate 202 (i.e., the coupling surfaces 222 will be inclined to the internal facets 45 formed by the coated transparent plate 202). The face 24a of the second waveguide 20 is ultimately formed by the coupling surfaces 222, so that a portion of the coupling surfaces 222 forms a portion of the interface plane between the two waveguides 10, 20.

[0084] The outer face of the optical structure 220 also includes a major face 234a (formed by the face 214a of the bonded stack 210, as will be discussed below) that abuts the coupling surface 222 at an angle. Figure 2GIn the illustrated embodiment, the angle of abutment between the coupling surface 222 and the face 234a is 90° (i.e., the coupling surface 222 is perpendicular to the face 234a). In other embodiments, the angle of abutment between the coupling surface 222 and the face 234a is an inclined angle, preferably an acute angle. Such an inclined angle embodiment is particularly suitable for producing a final optical device (optical aperture multiplier product) in which the facet 45 of the second optical waveguide 20 has an inclined angle relative to the first optical waveguide 10 (i.e., inclined relative to the faces 12a, 12b). The selection of a specific inclined (preferably acute) angle can be based on the optical design specifications of the final optical aperture multiplier product.

[0085] In some embodiments, along the cutting plane 204 ( Figure 2F ) cutting the bonded stack 210 (non-staggered or staggered) to produce the optical structure 220. In other embodiments, the optical structure 220 can be produced by grinding or polishing the bonded stack 210 to gradually remove material in the portion 211 of the bonded stack 210 until the cutting plane 204 is reached.

[0086] The cutting plane 204 is preferably inclined to the face 212a (and therefore inclined to the upper surface 203a and lower surface 203b of the plate 202 forming the stack 210 / optical structure 220), and at a certain angle relative to the face 214a, so that the cutting plane 204 passes through a portion of the faces 212a, 216b, and so that the resulting coupling surface 222 is also inclined to the face 212a and at a certain angle relative to the face 214a. As described above, in some embodiments, the angle of the cutting plane 204 relative to the face 214a can be 90° (i.e., the cutting plane 204 can be perpendicular to the face 214a), and in other embodiments can be an inclined (preferably acute) angle.

[0087] Typically, any deviation from the desired angle between the cutting plane 204 and the face 214a or any deviation from the desired angle between the resulting coupling surface 222 and the face 234a can be corrected by further polishing or slicing / cutting the optical structure 220 at the coupling surface 222 (i.e., at the location of the cutting plane 204). To avoid waste, the location of the cutting plane 204 in the optical structure 220 is preferably selected so that the length of the coupling surface 222 (at Figure 2G The length measured in the "z" direction in FIG. 10 ) corresponds to the length of sheet 110 (also in Figure 2A in the “z” direction).

[0088] In certain embodiments, the portion 211 of the bonded stack 210 that is removed (by cutting at the cutting plane 204 or grinding or polishing to the cutting plane 204) can be generally a triangular prism portion including the following faces: i) a first portion 231a of the face 212a (which can be a small portion of the face 212a), ii) two approximately triangular portions of the faces 214a, 214b, and iii) a portion of the face 216b (which can be a rectangular portion) 237. In embodiments where the plane 204 is perpendicular to the face 214a, the first portion 231a is a rectangular portion. In embodiments where the plane 204 is inclined to the face 214a, the first portion 231a is a non-parallelogram (and a "trapezoidal" in American English). Note that the principles used to define the term "face" in the context of the faces 214a, 214b, 216a, 216b also apply here in the context of the faces 234a, 234b, 236a, 236b.

[0089] Thus, in certain embodiments, the optical structure 220 (formed by removing portion 211) can have the following faces: i) a pair of preferably parallel faces 232a, 232b, wherein face 232a is a second portion of face 212a (which is the remaining portion of face 212a after removal of first portion 231a), and wherein face 232b is identical to face 212b, ii) a pair of preferably (but not necessarily) parallel trapezoidal or generally quadrilateral faces 234a, 234b, which can be perpendicular to face 232a. a, 232b and formed by removing triangular portions of faces 214a, 214b; iii) face 236a, which is identical to face 216a and may be perpendicular to faces 232a, 232b, 234a, 234b; iv) face 236b, which may be parallel to face 236a and is the portion of face 216b remaining after portion 237 is removed; and v) interface 222, which is inclined to face 232a (i.e., the portion of face 212a remaining after portion 211 is removed) and is perpendicular (e.g., Figure 2G ) or inclined (preferably at an acute angle) to surface 234a (ie, the remaining portion of surface 214a after portion 211 is removed).

[0090] In embodiments where plane 204 is perpendicular to face 214a, second portion 232a is a rectangular portion. In embodiments where plane 204 is inclined to face 214a, second portion 232a is a non-parallelogram (and a "trapezoidal" in American English).

[0091] Note that plane 204 provides (defines) a boundary between portion 231a and face 232a, and also provides a boundary between portion 237 and face 236b.

[0092] Likewise, any deviation from the desired angle between the coupling surface 222 and the face 234a may be corrected by polishing the optical structure 220 at the location of the cleavage plane 204. Indeed, since the coupling surface 222 ultimately forms part of the interface plane between the two waveguides 10, 20, it is preferred to polish the coupling surface 222 even in the absence of such angular deviations (or in the case where any such angular deviations are so small that they do not need to be corrected) to ensure that the coupling surface 222 is of high optical quality. In embodiments where the optical structure 220 is produced by polishing the bonded stack 210 to gradually remove material in the portion 211 of the bonded stack 210, no further polishing step may be required.

[0093] Now turn to Figure 2H , optically coupling the sheet 110 with the optical structure 220 to form an optical structure 240 (which is an intermediate work product of the optical aperture multiplier manufacturing process), whereby the faces 112a, 112b are parallel to the coupling surface 222 and whereby one of the faces 112a or 112b is in a facing relationship with the coupling surface 222. As an intermediate work product, the optical structure 240 includes the sheet 110 and the optical structure 220 as a first (or second) portion and a second (or first) portion, respectively. In an embodiment where the sheet 110 does not include any cover plate at the coupling face of the sheet 110 (i.e., the face 112a or the face 112b), the optical coupling causes one of the faces 112a or the face 112b to be attached to the coupling surface 222.

[0094] In the illustrated embodiment, face 112b is shown as being in a facing relationship with coupling surface 222, but face 112a may alternatively be in a facing relationship with coupling surface 222. The selection of which of face 112a, face 112b is to be in a facing relationship with coupling surface 222 may be based on the optical design specifications of the final optical aperture multiplier product, including, for example, the deployment position of the optical image generator relative to waveguide 10. Optical coupling may be achieved by adhesive bonding such that face 112b (or face 112a) and coupling surface 222 are bonded together. Alternatively, the optical coupling may be a mechanical coupling with an air gap of designed thickness between face 112b (or face 112a) and coupling surface 222. In an embodiment where the coupling surface (112b or 112a) of the sheet 110 has a cover plate, the optical coupling between the sheet 110 and the optical structure 220 causes the cover plate 120b (or 120a) to be optically attached to the coupling surface 222, which can be achieved by bonding the cover plate 120b (or 120a) and the coupling surface 222 so that the cover plate 120b (or 120a) and the coupling surface 222 are bonded together or by mechanical coupling with an air gap between the cover plate 120b (or 120a) and the coupling surface 222.

[0095] Then, along at least two parallel cutting planes (given by Figure 2H The optical structure 240 is cut (indicated by dashed lines 244 in FIG. 1 ) to produce one or more optical aperture multipliers. Fig.2I A single such optical aperture multiplier is shown in . It should be noted that the waveguide 10 has a cover plate 13a at face 12a which results from cutting the cover plate 120a at cutting plane 244 .

[0096] Despite Figure 2H and Fig.2I Only a single optical aperture multiplier is shown cut out of the optical structure 240 , but multiple optical aperture multipliers may be cut out of the optical structure 240 by increasing the size and / or number of plates 202 used to form the bonded stack 210 .

[0097] Note that in order to maintain consistent thickness (arbitrarily measured herein along the "z-axis") between multiple optical aperture multipliers cut from the optical structure 240, it is preferred that the cutting planes 244 be spaced at predetermined and uniform intervals.

[0098] The perpendicularity between the cutting plane 244 and the coupling surface 222 simultaneously achieves the following effects: i) parallelism between the faces 14a, 14b of the first optical waveguide 10, ii) perpendicularity between the first pair of parallel faces 12a, 12b and the second pair of parallel faces 14a, 14b (thereby achieving a rectangular cross-section formed by the faces 12a, 12b, 14a, 14b), and iii) parallelism between the faces 22a, 22b of the second optical waveguide 20.

[0099] To improve (optimal) performance, it is also preferred that the cutting plane 244 is perpendicular to the face 234a (and therefore perpendicular to the face 214a). In some embodiments, the cutting plane 244 can be parallel to the faces 114a, 114b, while in other embodiments, the cutting plane 244 can be inclined to the faces 114a, 114b.

[0100] In certain embodiments, the plane of the interior facets 40 of the sheet 110 is perpendicular to the cleaving plane 244. It should be noted that in embodiments where perpendicularity between the facets 40 and the cleaving plane 244 is desired, the sheet 110 and the optical structure 220 should be aligned with high precision to ensure minimal deviation from perpendicularity (e.g., within 20 arc seconds).

[0101] In other embodiments, the plane of the internal facets 40 of the sheet 110 is inclined to the cutting plane 244. In such embodiments, it is preferred that the angle between the facets 40 and the cutting plane 244 is not perpendicular at all, such as at least 10° from perpendicular, more preferably at least 20°.

[0102] To achieve the desired angle between facet 40 and cutting plane 244, sheet 110 is aligned with optical structure 220 before cutting out the optical aperture multiplier(s). Preferably, sheet 110 is aligned with optical structure 220 before the step of optically coupling them.

[0103] Alignment of the sheet 110 with the optical structure 220 can be performed in various ways. In one example, alignment is performed by holding the optical structure 220 in a fixed position and orientation and maintaining parallelism between the face 112b or cover plate 120b (or face 112a or cover plate 120a) and the coupling surface 222, and rotating the sheet 110 relative to the optical structure 220 (face 112b (or 120a) or cover plate 120b (or 120a) on the coupling surface 222) until the desired angle between the facet 40 and the cutting plane 244 is achieved (e.g., within 20 arc seconds of 90° if perpendicularity is desired, or, for example, 80° or less if an oblique angle between the facet 40 and the cutting plane 244 is desired). In another example, the sheet 110 is held in a fixed position and orientation, and the optical structure 220 is rotated relative to the sheet 110 while the face 112b or cover plate 120b (or the face 112a or cover plate 120a) is on and parallel to the coupling surface 222 until the desired angle between the facet 40 and the cutting plane 244 is achieved. In yet another example, neither the sheet 110 nor the optical structure 220 is held in a fixed position, and the sheet 110 and the optical structure 220 are relatively rotated in opposite directions while the face 112b or cover plate 120b (or the face 112a or cover plate 120a) is on and parallel to the coupling surface 222 until the desired angle between the facet 40 and the cutting plane 244 is achieved.

[0104] As an aside, it should be noted that the tilt angles of the coupling surface 222 relative to the upper and lower surfaces 203a, 203b of the plate 202 forming the stack 210 / optical structure 220 (and therefore the tilt angles of the cleaving plane 204 forming the coupling surface 222) partially define the tilt angles of the facets 45 of the second optical waveguide 20 of the final optical aperture multiplier product. This is primarily due to the interdependence of the orientations of the coupling surface 222 and the cleaving plane 244 (i.e., the cleaving plane 244 is perpendicular to the coupling surface 222). For example, as the angle between the plane 204 / coupling surface 222 and the surfaces 203a, 203b becomes shallower (i.e., as the coupling surface 222 becomes closer to being parallel to the face 216b), the cleaving plane 244 will produce facets 45 having shallower tilt angles relative to the faces 22a, 22b of the second optical waveguide 20. Similarly, as the angle between the plane 204 / coupling surface 222 and the surfaces 203a, 203b becomes steeper (i.e., as the coupling surface 222 becomes closer to parallel to the faces 212a, 212b), the cutting plane 244 will produce a facet 45 having a steeper tilt angle relative to the faces 22a, 22b of the second optical waveguide 20.

[0105] Refer again Fig.2I , note that the faces 14a, 22a of the optical aperture multiplier form a single continuous external face that is formed by cutting the optical structure 240 along one of the cutting planes 244. Similarly, the faces 14b, 22b of the optical aperture multiplier form a single continuous external face that is formed by cutting the optical structure 240 along the other of the cutting planes 244. The two continuous faces should be parallel (because the parallelism of the faces 14a, 14b and the faces 22a, 22b is critical to maintain the conditions for internal reflection of light through both optical waveguides 10, 20). The parallelism of the two continuous faces can be maintained by ensuring that the cutting plane 244 is a parallel plane. However, by polishing the continuous faces after cutting the optical structure 240 along the cutting plane 244, deviations from the parallelism of the continuous faces caused by deviations from the parallelism of the cutting plane 244 can be corrected. In addition, maintaining the parallelism of the two consecutive surfaces also maintains the perpendicularity between the two consecutive surfaces and the faces 12a, 12b, which ensures the perpendicularity (and the formation of a rectangular cross section) between the two pairs of parallel faces 12a, 12b, 14a, 14b of the first optical waveguide 10. This maintenance of parallelism and perpendicularity is critical in order to maintain image uniformity as the image light travels along the first optical waveguide 10 by quadruple internal reflection.

[0106] Despite FIG. 2A to FIG. 2INot shown, but either or both of the faces 22a, 22b may optionally have a transparent cover bonded thereto or otherwise optically coupled thereto. Such a transparent cover may be advantageously used to avoid double reflections within the LOE 20, i.e., situations where light reflects twice from the same facet 45, and specifically, the cover helps ensure that after reflecting once by the facet 45, the transmitted portion of the light will propagate above or below the facet and proceed directly to the next facet, thereby enhancing image uniformity. An example of an optical aperture multiplier having a transparent cover attached to the exterior face of the LOE 20 is described in commonly owned International Patent Application No. PCT / IL2022 / 050216, filed on February 24, 2022, and entitled “Optical Aperture Multipliers Having a Rectangular Waveguide.”

[0107] Now turn to FIG. 5A to FIG. 5D , which shows steps of a preferred method (process) that can be used to manufacture an optical aperture multiplier according to a second set of embodiments of the present invention. In principle, the second set of embodiments is similar to the first set of embodiments in that the second set of embodiments also employs the step of optically coupling the sheet 110 to an optical structure 320 to form a new optical structure, wherein one or more optical aperture multipliers can be extracted from the new optical structure by slicing along two or more cutting planes. However, as described above and as will become more apparent from the discussion below, the main difference between the two sets of embodiments is with respect to the optical structures 220, 320 to which the sheet 110 is optically coupled.

[0108] Now refer to Figure 5A and Figure 5B , the optical structure 320 is formed as a bonded stack 321 of LOEs 20, i.e., a stack of LOEs 20 bonded together. The resulting optical structure 320 (i.e., bonded stack 321) has multiple external faces including a pair of parallel surfaces 302a, 302b and multiple mutually parallel partially reflective internal surfaces (facets) 45 inclined to the surfaces 302a, 302b.

[0109] Each of the LOEs of the bond stack 321 is as described above with reference to Figure 1A and Figure 1B As described, that is, each of the LOEs has a plurality of external faces including a pair of parallel faces 22a, 22b (and additional faces 24a, 24b, 26a, 26b) and a plurality of internal facets 45 that are inclined to the external faces 22a, 22b. The internal facets 45 of each LOE 20 constitute a subset of the facets of the optical structure 320. Although the bonded stack 321 is Figure 5A and Figure 5B2 is shown as being formed of only five individual LOEs 20, but generally a greater number of LOEs may be used to form the stack, including, for example, ten or more LOEs, and in some cases twenty or more LOEs.

[0110] Methods for making such a single LOE 20 have been extensively described in various publications by Lummus Ltd. (Israel), including, for example, U.S. Pat. No. 7,634,214, U.S. Pat. No. 8,873,150, PCT Publication No. WO 2016 / 103263, and PCT Publication No. WO 2020 / 212835.

[0111] The outer surface of the optical structure 320 / bonded stack 321 also includes a planar coupling surface 322 (similar to the coupling surface 222 of the first set of embodiments) to which the sheet 110 is to be optically coupled. As will be discussed, the coupling surface 322 can be formed by the face 24a of the constituent LOE that forms the bonded stack 321. The outer surface of the optical structure 320 / bonded stack 321 can also include a rear surface 306a (e.g., formed by aligning the face 26a of the LOE so as to be coplanar), a front surface 306b opposite the rear surface 306a (e.g., formed by aligning the face 26b of the LOE so as to be coplanar), and a top (or upper) surface 308 opposite the coupling surface 322 (e.g., formed by aligning the face 24b of the LOE so as to be coplanar). In certain embodiments, the optical structure 320 / bonded stack 321 is a rectangular cube whereby surfaces 306a and 306b and surfaces 308 and 322 are each a pair of parallel surfaces and whereby the three pairs of parallel surfaces 302a, 302b, 306a, 306b, 308, 322 are mutually perpendicular.

[0112] In certain embodiments, for example FIG. 5A to FIG. 5D In the illustrated embodiment, the bonded stack 321 of LOE 20 may also include a plurality of transparent spacers 324, and the LOE 20 and the spacers 324 are alternated along the length of the bonded stack 321 perpendicular to the faces 22a, 22b of the LOE 20. Portions of these transparent spacers 324 form a transparent cover sheet bonded to the faces 22a, 22b of the final optical aperture multiplier product. In such an embodiment, a given spacer 324 is bonded to two adjacent LOEs such that the face 22a of the first adjacent LOE is bonded to one side of the spacer 324 and the face 22b of the second adjacent LOE is bonded to the opposite side of the spacer 324.

[0113] In embodiments where transparent spacers 324 are not employed, adjacent LOEs are bonded together such that face 22a of each LOE is joined to face 22b of an adjacent LOE.

[0114] To form the bonded stack 321, the LOE 20 is preferably aligned so that all faces 22a, 22b of the LOE are parallel to one another, and so that all internal facets 45 of the LOE are parallel to one another (eg, Figure 5A and Figure 5B 322). In addition, the faces 24a of the LOE 20 may be aligned so as to be coplanar, thereby forming a coupling surface 322. In an embodiment having a spacer 324, the alignment of the faces 24a may also include the alignment of the smaller outer surfaces of the spacer 324. It should be noted that if the faces 24a are not aligned to be coplanar, the bonded stack 321 may be cut and polished along a plane perpendicular to the faces 22a, 22b of the LOE 20 to remove extraneous portions of one or more of the LOEs to produce the coupling surface 322.

[0115] A pair of parallel surfaces 302a, 302b of the optical structure 320 are parallel to the faces 22a, 22b of each LOE 20. In addition, in the embodiment where the spacer 324 is provided, the surface 302a is formed by one end ( Figure 5B The right end of the stack 321 is formed by the partition 324 at the right end of the stack 321, and the surface 302b is formed by the opposite end of the stack 321 ( Figure 5B Incidentally, the two partitions 324 at the ends of the stack 321 may have an increased thickness relative to the partitions 324 at the inner portion of the stack 321. In addition, the partitions 324 at the inner portion of the stack preferably have a common (ie, the same) thickness.

[0116] In the embodiment where the partition 324 is not provided, the surface 302a is formed by one end of the stack 321 ( Figure 5B The right end of the stack 321 is formed by the face 22a of the LOE, and the surface 302b is formed by the opposite end of the stack 321 ( Figure 5B The surface 22b of the LOE at the left end of the image is formed.

[0117] like Figure 5C As shown, the sheet 110 is optically coupled with the optical structure 320 / bonded stack 321 to form an optical structure 340 (which is an intermediate work product of the optical aperture multiplier manufacturing process), whereby the faces 112a, 112b are parallel to the coupling surface 322 and whereby one of the faces 112a or 112b is in a facing relationship with the coupling surface 322. As an intermediate work product, the optical structure 340 includes the sheet 110 and the optical structure 320 (bonded stack 321) as the first (or second) and second (or first) parts, respectively. It should be noted that, as an illustrative example only, Figure 5C A bonded stack formed into 18 LOEs is shown (with Figure 5A and Figure 5B ) compared to the five LOE stack shown in FIG. 3 .

[0118] Note that although Figure 5C Sheet 110 is shown as having a single cover sheet (cover sheet 120a attached to face 112a), but it is understood that face 112b (which is the coupling face of sheet 110) may also have cover sheet 120b bonded thereto.

[0119] In an embodiment where the sheet 110 does not include any cover plate at the coupling face of the sheet 110 (i.e., face 112a or face 112b), the optical coupling between the sheet 110 and the optical structure 320 is such that one of the face 112a or face 112b is attached to the coupling surface 322. In the illustrated embodiment, the face 112a is shown as being in a facing relationship with the coupling surface 322, but the face 112b may also be in a facing relationship with the coupling surface 322. The optical coupling may be achieved by adhesive bonding such that the face 112a (or face 112b) and the coupling surface 322 are bonded together. Alternatively, the optical coupling may be a mechanical coupling with an air gap of designed thickness between the face 112a (or face 112b) and the coupling surface 322.

[0120] In an embodiment where the coupling surface (112b or 112a) of the sheet 110 has a cover plate, the optical coupling between the sheet 110 and the optical structure 320 causes the cover plate 120a (or 120b) to be optically attached to the coupling surface 322, which can be achieved by bonding the cover plate 120a (or 120b) to the coupling surface 322 so that the cover plate 120a (or 120b) and the coupling surface 322 are bonded together or by mechanical coupling with an air gap between the cover plate 120a (or 120b) and the coupling surface 322.

[0121] Then, at least two preferably parallel cutting planes (defined by Figure 5C The optical structure 340 is cut (indicated by dashed lines 344 in FIG. 5 ) to produce one or more optical aperture multipliers. Figure 5D A single such optical aperture multiplier 1' is shown in FIG. Fig.2I The optical aperture multiplier 1 of the waveguide 10 has a cover plate 13a at the face 12a, which is produced by cutting the cover plate 120a at the cutting plane 344. Fig.2I In contrast to the optical aperture multiplier 1 of , the optical aperture multiplier 1 ′ further has cover plates 39a, 39a (formed by cutting through the continuous partition 324) attached to the faces 22a, 22b.

[0122] Despite Figure 5C and Figure 5DOnly a single optical aperture multiplier is shown cut out of the optical structure 340 , but a plurality of optical aperture multipliers may be cut out of the optical structure 340 .

[0123] Any deviation from the parallelism of the cutting plane 344 relative to the faces 22a , 22b can be corrected by polishing the cut optical aperture multiplier at the line of sight / position of the cut along the cutting plane 344 .

[0124] In the embodiment using transparent partitions 324, two continuous cutting planes 344 are located in the continuous partition of one of the LOEs 20 in which the bonded stack 321 is sandwiched. Preferably, each cutting plane is located at the center of the corresponding partition 324 so as to effectively divide the partition 324 into two approximately equal parts. It should be noted that in the case where it is desired to bond a transparent cover plate to the faces 22a, 22b of the waveguide 20, the manufacture of the optical aperture multiplier according to the second group of embodiments may be superior to the manufacture according to the first group of embodiments. This is because the manufacture of the optical aperture multiplier according to the second group of embodiments allows the cover plate (in Figure 5D 39a and 39b) are flush with the side surfaces 14a, 14b of the waveguide 10, thereby providing a flat construction in which the cover does not protrude beyond the surfaces 14a, 14b (which may occur when the cover is applied to the waveguide 20 manufactured according to the first set of embodiments).

[0125] In an embodiment where a transparent partition 324 is not employed, it is preferred that the continuous cutting planes 344 are located between the faces 22a, 22b of the continuous LOE 20 of the bonded stack 321, and more preferably located at the bonding area formed between the faces 22a, 22b of the continuous LOE 20, so that each cut-out optical aperture multiplier has only one of the LOEs 20 of the bonded stack 321. For example, a first cutting plane preferably passes between the bonding area between the face 22b of the first LOE 20 and the face 22a of the second LOE 20, wherein the second LOE 20 is adjacent to and bonded to the first LOE 20. A second cutting plane adjacent to the first cutting plane passes between the bonding area between the face 22b of the second LOE 20 and the face 22a of the third LOE 20, wherein the third LOE 20 is adjacent to and bonded to the second LOE 20. It should be noted herein that the bonding area (formed between the faces 22a, 22b of the continuous LOE 20) can provide a guide for the arrangement of the cutting planes 344.

[0126] Prior to forming the optical structure 340 (with or without the spacers 324), the sheet 110 and the optical structure 320 are preferably properly aligned so as to be aligned similarly to the above reference. Figure 2HThe enhanced optical performance is achieved in the manner described. For example, the sheet 110 and the optical structure 320 are preferably aligned so that the surface 302a is parallel to (and preferably coplanar with) one of the faces 114a or 114b, and so that the surface 302b is parallel to (and preferably coplanar with) the other of the faces 114b or 114a. The sheet 110 and the optical structure 320 may also be preferably aligned so that the surface 306a is parallel to (and preferably coplanar with) one of the faces 116a or 116b, and so that the surface 306b is parallel to (and preferably coplanar with) the other of the faces 116b or 116a. This preferred alignment is Figure 5C Shown in.

[0127] Alignment may be achieved by rotating sheet 110 relative to optical structure 320, similar to that described above in discussing alignment of sheet 110 and optical structure 220. It should also be noted that alignment and optical coupling between sheet 110 and optical structure 320 necessarily causes facet 40 to be non-parallel to facet 45.

[0128] Note that in the embodiments described herein, the sheet 110 has an initial direction of elongation (arbitrarily shown herein as corresponding to the "z-axis") that is perpendicular to the direction of elongation of the waveguide 10 and also generally perpendicular to the cleavage planes 244, 344. This direction of elongation of the sheet 110 enables extraction of multiple optical aperture multipliers from the optical structure (240 or 340), thereby extracting the waveguide 10 portion of each extracted optical aperture multiplier from the sheet 110 portion of the optical structure (240 or 340).

[0129] It should be noted that one or more additional optical components may be optically coupled or bonded to the optical aperture multiplier product produced using the methods described herein at one or more external faces of the waveguide. Examples of such optical components include, for example, optical coupling-in structures, polarizers, depolarizers, and lenses. An optical coupling-in structure in the form of an external coupling prism or external coupling reflector arrangement is used to introduce / inject collimated image light from an optical image generator into the first optical waveguide 10 such that the injected image advances through the first optical waveguide 10 by quadruple internal reflection.

[0130] By way of one set of examples, any of the coupling prisms described in U.S. Pat. No. 10,133,070, e.g., with reference to FIGS. 8A to 14C of that document, may be bonded or otherwise optically coupled to the first optical waveguide 10 to provide light injection to the first optical waveguide 10. In some cases, attachment of such coupling prisms may require applying additional coatings to portions of the outer waveguide faces 12a, 12b, 14a, 14b and / or cutting or otherwise removing a portion of the first optical waveguide 10.

[0131] In another set of examples, a coupling prism (which in certain configurations may also include a coupling reflector on one face of the coupling prism) may be deployed in association with a portion of the front face 14a or rear face 14b of the first optical waveguide 10, such as described in co-owned International Patent Application No. PCT / IL2022 / 050216, entitled “Optical Aperture Multipliers Having a Rectangular Waveguide,” filed on February 24, 2022. Such a deployment may require dividing the face 12a or face 12b into a first region (corresponding to a majority of the face 12a or face 12b) and a second region (corresponding to the remainder of the face 12a or face 12b) having different optical properties. The subdivision may be achieved by a coating or material deployed in association with a majority or minority portion of the face 12a or face 12b, which may be achieved by applying such a coating or material to a required portion of the face 112a or face 112b of the sheet 110.

[0132] The optical image generator that provides a collimated image to the optical coupling-in structure is typically a microprojector optical device that includes at least one light source that is typically arranged to illuminate a spatial light modulator, such as a liquid crystal on silicon (LCoS) chip. The spatial light modulator modulates the projected intensity of each pixel of the image to generate the image. Alternatively, the optical image generator may include a scanning arrangement, typically implemented using a fast scanning mirror, that scans illumination from a laser source across an image plane of the image generator while varying the intensity of the beam on a pixel-by-pixel basis in sync with the scanning motion to project the desired intensity for each pixel. In both cases, collimating optics are provided to generate an output projected image that is collimated to infinity. Some or all of the above-mentioned components of the image generator are typically arranged on the surface of one or more polarizing beam splitter cubes or other prism arrangements known in the art.

[0133] As described above, it may be desirable to provide one or more additional optical components, in particular optical coupling-in components, to be optically coupled to the optical aperture multiplier. To this end, it may be particularly advantageous to provide an additional optical structure, from which the optical coupling-in components may be extracted, which additional optical structure may be optically coupled to the above optical structure, so as to be able to produce a large number of optical aperture multipliers, each optical aperture multiplier having a pair of waveguides and an optical coupling-in structure attached thereto or otherwise optically coupled thereto. With this in mind, FIG. 6A to FIG. 6E Steps of a method (process) that may be used to fabricate an optical aperture multiplier having a waveguide 10, 20 and an optical coupling-in configuration bonded to (or otherwise optically coupled with) the waveguide 10 are shown according to an embodiment of the present invention. Fig. 6A An additional optical structure 420 is shown from which a plurality of optical incoupling configurations may be extracted, and FIG. 6B to FIG. 6E The optical structure 500 formed by optically coupling the optical structure 420 with the optical structure 340 and extracting the optical aperture multiplier from the optical structure 500 is shown. It should be noted that although the optical structure 500 is provided in the context of the manufacturing process according to the second set of embodiments, FIG. 6B to FIG. 6D Although the examples are shown in , similar techniques can also be applied to the manufacturing process according to the first group of embodiments.

[0134] Now turn to the details FIG. 6A to FIG. 6E , the optical structure 420 is formed of a light-transmitting material and has a plurality of external surfaces including a pair of parallel surfaces 402a, 402b and a plurality of mutually parallel internal surfaces 50 inclined to the surfaces 402a, 402b. The external surfaces of the optical structure 420 may further include surfaces 404a, 404b (in some embodiments, the surfaces 404a and 404b may be a pair of parallel surfaces perpendicular to the surfaces 402a, 402b) and surfaces 406a, 406b (in some embodiments, the surfaces 406a and 406b may be a pair of parallel surfaces and may also be perpendicular to the surfaces 402a, 402b, 404a, 404b).

[0135] In some embodiments, inner surface 50 is a reflective surface, while in other embodiments, inner surface 50 is a partially reflective surface (e.g., a beam splitting surface). As described above, optical structure 420 can be obtained in a variety of ways, including by stacking and bonding transparent sheets (which may be coated with a reflective or partially reflective coating) together and then slicing the bonded sheets in a manner similar to that used to produce sheet 110.

[0136] like FIG. 6B to FIG. 6D As shown, optical structure 420 is optically coupled to the sheet 110 portion of optical structure 340 such that a coupling face of optical structure 420 (which may be one of faces 402a, 402b) is in facing relationship with one of the exterior faces of sheet 110. The optical coupling between optical structures 340, 420 produces a new optical structure 500 having an intermediate working product of three parts: 1) a bonded stack of LOE portions (i.e., optical structure 320), 2) a sheet 110 portion, and 3) an optical structure 420 portion.

[0137] In the illustrated embodiment, the coupling face of the optical structure 420 is face 402a, which is disposed in a facing relationship with face 116b of the sheet 110. In certain embodiments, the optical structure 420 is bonded to the sheet 110 such that the coupling face (e.g., face 402a) is bonded to face 116b (or face 116a). Note that the choice of which of the external faces of the sheet 110 is placed in a facing relationship with the coupling face of the optical structure 420 can be based on the optical design specifications of the final optical aperture multiplier product, including, for example, the deployment position of the optical image generator relative to the optical coupling-in configuration and the waveguide 10.

[0138] Prior to optically coupling the optical structure 420 to the sheet 110, the optical structure 420 and the sheet 110 are preferably aligned. In the illustrated embodiment, the alignment is preferably such that each inner surface 50 corresponds to and is preferably located between the faces 22a, 22b of a corresponding one of the LOEs of the bonded stack 321. In certain embodiments, the alignment is such that each inner surface 50 extends between the faces 22a, 22b of the corresponding LOE. The alignment further causes the inner surface 50 to be non-parallel to the facets 40 and 45.

[0139] In certain embodiments, alignment of optical structure 420 with sheet 110 is also such that face 114a is parallel (and preferably coplanar) with face 406a, and such that face 114b is parallel (and preferably coplanar) with face 406b.

[0140] Fig.6D An exemplary cutting plane 344 (with Figure 5C The optical structure 500 is cut along two or more cutting planes 344 to produce (extract / cut out) one or more optical aperture multipliers. Fig. 6E A single such cut-out optical aperture multiplier 1″ is shown having a pair of waveguides ( 10 , 20 ) and a coupling-in structure 42 attached to the pair of waveguides. The optical coupling-in structure 42 is produced by an optical structure 420 and includes a single inner surface 50 .

[0141] Note that although FIG. 6A to FIG. 6E In the embodiment shown, the sheet 110 is shown without the cover panels 120a, 120b, but it should be understood that one or both of the cover panels 120a, 120b may be applied to the corresponding faces 112a, 112b.

[0142] As described above, similar techniques for producing an optical aperture multiplier with additional optical coupling structures can be used with the manufacturing process according to the first set of embodiments. For example, the optical structure 420 can be used with Figure 2HThe optical structure 240 is optically coupled, for example, at the face 116b to produce an optical aperture multiplier having a pair of waveguides 10, 20 and an optical coupling structure 42 attached to the pair of waveguides.

[0143] It should be noted that the optical structure 420 shown in the accompanying drawings is only one non-limiting example of an optical structure from which an optical coupling configuration can be extracted. In general, any optical structure having a coupling surface (e.g., face 402a) and multiple optical coupling surfaces (e.g., inner surface 50) or elements or surface portions geometrically associated with the coupling surface can be optically coupled to the optical structure 340 or 240. An elongated prism is another non-limiting example of an optical structure from which an optical coupling configuration can be extracted. Such an elongated prism can have multiple outer surfaces, which include a coupling surface (for optical coupling with the sheet 110) and an optical coupling surface that can be subdivided into multiple non-overlapping portions. Each portion can correspond to, for example, a different respective LOE 20 of the optical structure 320, such that when sliced ​​along the cutting plane 344, each portion becomes an optical coupling surface of an optical aperture multiplier.

[0144] The alignment of the various optical structures described herein can be performed using any suitable optical alignment device / equipment / tool ​​that performs a suitable optical alignment technique / method. Such suitable optical alignment devices / equipment / tools may include, for example, one or more computerized control devices, one or more computerized processing devices, one or more optical subsystems having, for example, one or more light sources, one or more light detectors / sensors (including optical sensors), one or more optical components (e.g., one or more lenses, one or more folded optical devices, one or more prisms, etc.), automatic collimators, etc. Details of non-limiting examples of suitable optical alignment devices / equipment / tools / methods that can be used to align the various optical structures described herein can be found in various publications of Lummus Ltd. (Israel), including, for example, International Patent Application No. PCT / IL2021 / 051377 and International Patent Application No. PCT / IL2021 / 051378.

[0145] The present disclosure has described various cutting steps in which optical structures or materials are cut along cutting planes to produce various other optical structures or optical products. It should be noted that in some embodiments, some or all surfaces of these optical structures and materials (including and especially these surfaces produced by these cutting steps) can be polished to, for example, improve optical quality. In some embodiments, polishing can be performed as part of these cutting steps or after these cutting steps and before subsequent optical coupling (e.g., bonding) steps. As will be appreciated by those of ordinary skill in the art, in the above-described manufacturing methods, the cutting or slicing of the various optical structures described herein can be performed by any suitable cutting device / equipment / tool. As will be appreciated by those of ordinary skill in the art, the polishing of the faces and surfaces of the various optical structures described herein can be performed by any suitable polishing device / equipment / tool.

[0146] The description of various embodiments of the present disclosure has been presented for illustrative purposes, but the description is not intended to be exhaustive or limited to the disclosed embodiments. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The terms used herein are selected to best explain the principles of the embodiments, practical applications or technical improvements to technologies existing in the marketplace, or to enable those of ordinary skill in the art to understand the embodiments disclosed herein.

[0147] As used herein, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0148] The word “exemplary” is used herein to mean “serving as an example, instance, or illustration.” Any implementation described as “exemplary” is not necessarily to be construed as preferred or advantageous over other implementations and / or to exclude the incorporation of features from other implementations.

[0149] It should be understood that, for the sake of clarity, certain features of the invention described in the context of separate embodiments may also be provided in combination in a single embodiment. Conversely, for the sake of brevity, various features of the invention described in the context of a single embodiment may also be provided individually or in any suitable subcombination or as appropriate 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 does not function without those elements.

[0150] Although the present invention has been described in conjunction with specific embodiments of the present invention, it is apparent that many alternatives, modifications and variations are apparent to those skilled in the art. Therefore, the present invention is intended to include all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims.

[0151] In addition, the present disclosure also provides the following configuration.

[0152] 1. A method for manufacturing an optical aperture multiplier (1, 1', 1"), comprising:

[0153] Obtaining a sheet (110) having: a plurality of exterior faces including a pair of parallel faces (112a, 112b), and a first plurality of mutually parallel partially reflective interior surfaces (40) inclined to the pair of parallel faces (112a, 112b);

[0154] Obtaining a first optical structure (220, 320), the first optical structure having: a plurality of outer surfaces including a planar coupling surface (222, 322), and a second plurality of mutually parallel partially reflective inner surfaces (203a, 45) inclined to the coupling surface (222, 322);

[0155] Optically coupling the sheet (110) to the first optical structure such that one of the pair of parallel faces (112a, 112b) is in a facing relationship with the coupling surface (222, 322), thereby forming a second optical structure (240, 340); and

[0156] At least one optical aperture multiplier (1, 1', 1") is cut out from the second optical structure (240, 340) by cutting the second optical structure (240, 340) through at least two cutting planes (244, 344) perpendicular to the coupling surface (222, 322).

[0157] 2. A method according to configuration 1, wherein the first optical structure (320) is formed as a bonded stack (321) of light-guiding optical elements (LOEs) (20), each LOE (20) of the bonded stack (321) having a pair of main parallel surfaces (22a, 22b) and a subset of a second plurality of mutually parallel partially reflective inner surfaces (45) inclined to the pair of main parallel surfaces (22a, 22b).

[0158] 3. The method according to configuration 2, wherein the at least two cutting planes (344) are substantially parallel to the main parallel surfaces (22a, 22b) of the continuous LOE (20).

[0159] 4. A method according to configuration 2, wherein the bonded stack (321) includes a plurality of transparent spacers (324), wherein the LOE (20) and the transparent spacers (324) alternate along the length of the main parallel surfaces (22a, 22b) of the bonded stack (321) perpendicular to the LOE (20).

[0160] 5. The method of configuration 4, wherein the at least two cutting planes (344) are located in a continuous partition (324) between which one of the LOEs (20) is sandwiched.

[0161] 6. The method according to configuration 1, wherein the first optical structure (220) is produced by a bonded stack (210) of coated transparent plates (202).

[0162] 7. A method according to configuration 6, wherein the bonded stack (210) has a pair of faces (214a, 214b), and wherein the first optical structure (220) is produced from the bonded stack (210) by cutting the bonded stack (210) along a cutting plane (204), and the cutting plane (204) is at a certain angle relative to at least one face (214a) of the pair of faces (214a, 214b) of the bonded stack (210).

[0163] 8. The method according to configuration 7, wherein the first optical structure (220) is produced from the bonded stack (210) by further polishing or slicing at the location of the cutting plane (204) to form the coupling surface (222).

[0164] 9. The method according to configuration 1, further comprising:

[0165] A third optical structure (420) is obtained, wherein the third optical structure has: a plurality of external surfaces including a coupling surface (402a), and a plurality of mutually parallel internal surfaces (50) inclined to the coupling surface (402a); and

[0166] Before cutting out the at least one optical aperture multiplier (1"), the third optical structure (420) is optically coupled to the sheet (110) such that a coupling surface (402a) of the third optical structure (420) is in a facing relationship with one of the external surfaces of the sheet (110).

[0167] 10. A method for manufacturing an optical aperture multiplier (1, 1', 1"), comprising:

[0168] Obtaining a bonded stack (321) of light-guiding optical elements (LOEs) (20), each LOE (20) of the bonded stack (321) having a pair of main parallel surfaces (22a, 22b) and a first plurality of mutually parallel partially reflective inner surfaces (45) inclined to the pair of main parallel surfaces (22a, 22b);

[0169] Obtaining a sheet (110) having: a plurality of exterior surfaces including a pair of parallel surfaces (112a, 112b), and a second plurality of mutually parallel partially reflective interior surfaces (40) inclined to the pair of parallel surfaces (112a, 112b);

[0170] Optically coupling the sheet (110) to the bonded stack such that one of the pair of parallel faces (112a, 112b) is in facing relationship with a coupling surface (322) of the bonded stack (321), and such that the pair of parallel faces (112a, 112b) are perpendicular to the pair of major parallel surfaces (22a, 22b) of each LOE (20) of the bonded stack (321), thereby forming an optical structure (340); and

[0171] At least one optical aperture multiplier (1, 1', 1") is cut out of the optical structure (340) by cutting the optical structure (340) through at least two cutting planes (344) that are substantially parallel to the main parallel surfaces (22a, 22b) of the continuous LOE (20) and perpendicular to the coupling surface (322) of the bonded stack (321).

[0172] 11. A method for manufacturing an optical aperture multiplier (1, 1', 1"), comprising:

[0173] Obtaining a sheet (110) having: a plurality of external surfaces including a pair of parallel surfaces (112a, 112b), and a plurality of mutually parallel partially reflective internal surfaces (40) inclined to the pair of parallel surfaces (112a, 112b);

[0174] A first optical structure (220) having a plurality of outer surfaces is produced from a bonded stack (210) of coated transparent plates (202), the plurality of outer surfaces including a coupling surface (222) inclined to the main surfaces (203a, 203b) of the coated transparent plates (202);

[0175] optically coupling the sheet (110) with the first optical structure (220) such that one of the pair of parallel faces (112a, 112b) is in a facing relationship with the coupling surface (222), thereby forming a second optical structure (240); and

[0176] At least one optical aperture multiplier (1) is cut out from the second optical structure (240) by cutting the second optical structure (240) through at least two cutting planes (244) perpendicular to the coupling surface (222).

[0177] 12. The method according to any one of configurations 1, 2, 6, 10 or 11, further comprising: optically coupling a cover plate (120a, 120b) to the sheet (110) at one or more of the pair of parallel surfaces (112a, 112b).

[0178] 13. The method according to configuration 12, wherein the cover plate (120a, 120b) includes a reflective coating.

[0179] 14. The method of configuration 12, wherein optically coupling the cover plate (120a, 120b) to the sheet (110) comprises bonding the cover plate (120a, 120b) to one or more of the pair of parallel surfaces (112a, 112b).

[0180] 15. The method according to configuration 14, wherein the bonding is performed using an optical glue having a refractive index lower than the refractive index of the material used to produce the sheet (110).

[0181] 16. A method according to configuration 12, wherein the cover plate (120a, 120b) is optically coupled to the sheet (110) at one of the pair of parallel surfaces (112a, 112b) that is in a facing relationship with the coupling surface (222, 322), and wherein the cover plate (120a, 120b) has polarization management properties.

[0182] 17. The method according to configuration 16, wherein the cover plate (120a, 120b) includes at least one of a wave plate or a polarizer.

[0183] 18. An optical structure (240, 340) which is an intermediate work product of a process for manufacturing an optical aperture multiplier (1, 1', 1"), the optical structure comprising:

[0184] A first portion (110) comprising: a plurality of exterior surfaces including a pair of parallel surfaces (112a, 112b), and a first plurality of mutually parallel partially reflective interior surfaces (40) inclined to the pair of parallel surfaces (112a, 112b); and

[0185] A second portion (220, 320) comprising: a plurality of outer surfaces including a coupling surface (222, 322), and a second plurality of mutually parallel partially reflective inner surfaces (203a, 45) inclined to the coupling surface (222, 322), wherein the second portion (220, 320) is optically coupled to the first portion (110) such that one of the pair of parallel faces (112a, 112b) is in a facing relationship with the coupling surface (222, 322), and such that at least one optical aperture multiplier (1, 1', 1") is produced when the optical structure (230, 240) is sliced ​​by at least two substantially parallel cutting planes (244, 344) passing through the first portion (110) and the second portion (220, 320) and perpendicular to the coupling surface (222, 322).

[0186] 19. An optical structure (340) which is an intermediate work product of a process for manufacturing an optical aperture multiplier (1, 1', 1"), the optical structure comprising:

[0187] a second portion (110) comprising: a plurality of outer surfaces including a pair of parallel surfaces (112a, 112b), and a second plurality of mutually parallel partially reflective inner surfaces (40) inclined to the pair of parallel surfaces (112a, 112b); and

[0188] A second part (320) comprising a bonded stack (321) of light-guiding optical elements (LOEs), each LOE (20) of the bonded stack (321) having a pair of main parallel surfaces (22a, 22b) and a first plurality of mutually parallel partially reflective inner surfaces (45) inclined to the pair of main parallel surfaces (22a, 22b), wherein the first part (110) is optically coupled to the second part (320) such that one of the pair of parallel surfaces (112a, 112b) is in a facing relationship with a coupling surface (322) of the second part (320), and such that the pair of parallel surfaces (112a, 112b) are perpendicular to the pair of main parallel surfaces (22a, 22b) of each of the LOEs (20) of the bonded stack (321).

[0189] 20. An optical structure (240) which is an intermediate work product of a process for manufacturing an optical aperture multiplier (1), the optical structure (240) comprising:

[0190] A first portion (110) having: a plurality of outer surfaces including a pair of parallel surfaces (112a, 112b), and a plurality of mutually parallel partially reflective inner surfaces (40) inclined to the first pair of parallel surfaces (112a, 112b); and

[0191] A second part (220) formed by a bonded stack (210) of coated transparent plates (202), the second part having a plurality of outer surfaces, the plurality of outer surfaces including a coupling surface (222) inclined to a major surface (203a, 203b) of the coated transparent plate (202), the first part (110) being optically coupled to the second part (220) such that one face (112b) of the pair of parallel faces (112a, 112b) is in a facing relationship with the coupling surface (222), and such that at least one optical aperture multiplier (1, 1', 1") is produced when the optical structure (240) is sliced ​​by at least two substantially parallel cutting planes (244) passing through the first part (110) and the second part (220) and perpendicular to the coupling surface (222).

[0192] 21. The optical structure (240, 340) according to any one of configurations 18, 19 or 20, further comprising: a cover plate (120a, 120b), the cover plate being optically coupled to the first portion (110) at one or more surfaces of the pair of parallel surfaces (112a, 112b).

[0193] 22. The optical structure (240, 340) according to configuration 21, wherein the cover plate (120a, 120b) includes a reflective coating.

[0194] 23. An optical structure (240, 340) according to configuration 21, wherein the cover plate (120a, 120b) is optically coupled to the first part (110) by bonding the cover plate (120a, 120b) to one of the pair of parallel surfaces (112a, 112b).

[0195] 24. The optical structure (240, 340) according to configuration 23, wherein the bonding is performed using an optical glue having a refractive index lower than a refractive index of a material used to produce the first portion (110).

[0196] 25. An optical structure (240, 340) according to configuration 21, wherein the cover plate (120a, 120b) is optically coupled to the first portion (110) at one of the pair of parallel surfaces (112a, 112b) that is in a facing relationship with the coupling surface (222, 322), and wherein the cover plate (120a, 120b) has polarization management properties.

[0197] 26. The optical structure (240, 340) of configuration 25, wherein the cover plate (120a, 120b) comprises at least one of a wave plate or a polarizer.

Claims

1. A method for manufacturing an optical aperture multiplier, comprising: obtaining a bonded stack of light guide optical elements (LOEs), each LOE of the bonded stack having a pair of main parallel surfaces and a first plurality of mutually parallel partially reflective inner surfaces inclined to the pair of main parallel surfaces; obtaining a sheet having: a plurality of exterior faces including a pair of parallel faces, and a second plurality of mutually parallel partially reflective interior faces oblique to the pair of parallel faces; optically coupling the sheet to the bonded stack such that one of the pair of parallel faces is in facing relationship with a coupling surface of the bonded stack and such that the pair of parallel faces are perpendicular to the pair of major parallel surfaces of each of the LOEs of the bonded stack to form an optical structure; as well as At least one optical aperture multiplier is cut out of the optical structure by cutting the optical structure through at least two cutting planes, the at least two cutting planes being substantially parallel to the main parallel surfaces of the continuous LOE and perpendicular to the coupling surfaces of the bonded stack.

2. The method according to claim 1, further comprising: A cover plate is optically coupled to the sheet at one or more of the pair of parallel faces.

3. The method according to claim 1, wherein: The cover plate includes a reflective coating.

4. The method according to claim 1, wherein: Optically coupling the cover plate to the sheet includes bonding the cover plate to one or more of the pair of parallel surfaces.

5. The method according to claim 1, wherein: The bonding is performed using an optical glue having a refractive index lower than that of the material used to produce the sheet.

6. The method according to claim 1, wherein: The cover plate is optically coupled to the sheet at one of the pair of parallel faces in facing relationship with the coupling surface, and wherein the cover plate has polarization management properties.

7. The method according to claim 1, wherein: The cover plate includes at least one of a wave plate or a polarizer.

8. An optical structure which is an intermediate work product of an optical aperture multiplier manufacturing process, the optical structure comprising: a first portion comprising: a plurality of exterior surfaces including a pair of parallel surfaces, and a second plurality of mutually parallel partially reflective interior surfaces inclined to the pair of parallel surfaces; and a second portion comprising a bonded stack of light-guiding optical elements (LOEs), each LOE of the bonded stack having a pair of major parallel surfaces and a first plurality of mutually parallel partially reflective inner surfaces inclined to the pair of major parallel surfaces, wherein the first portion is optically coupled to the second portion such that one of the pair of parallel faces is in a facing relationship with a coupling surface of the second portion, and such that the pair of parallel faces are perpendicular to the pair of major parallel surfaces of each of the LOEs of the bonded stack.

9. The optical structure according to claim 8, further comprising: A cover plate optically coupled to the first portion at one or more of the pair of parallel faces.

10. The optical structure according to claim 8, wherein: The cover plate includes a reflective coating.

11. The optical structure according to claim 8, wherein: The cover plate is optically coupled to the first portion by bonding the cover plate to one of the pair of parallel surfaces.

12. The optical structure according to claim 8, wherein: The bonding is performed using an optical glue having a refractive index lower than the refractive index of the material used to produce the first portion.

13. The optical structure according to claim 8, wherein: The cover plate is optically coupled to the first portion at one of the pair of parallel faces in facing relationship with the coupling surface, and wherein the cover plate has polarization management properties.

14. A manufacturing method comprising: arranging a plurality of coated transparent sheets having major surfaces into a staggered stack, and bonding the coated transparent sheets together to form a bonded staggered stack; cutting the bonded staggered stack along a cutting plane passing through at least some of the coated transparent plates and oblique to the major surfaces of the coated transparent plates to produce a first optical structure having a plurality of external surfaces including coupling surfaces at the cutting plane; Obtaining a second optical structure, the second optical structure having: a plurality of outer surfaces including a pair of parallel surfaces, and a plurality of mutually parallel partially reflective inner surfaces inclined to the pair of parallel surfaces; as well as The first optical structure is optically coupled to the second optical structure such that one of the pair of parallel faces is in facing relationship with the coupling surface to form a third optical structure.

15. The manufacturing method according to claim 14, further comprising: At least one optical aperture multiplier is cut out of the third optical structure by cutting the third optical structure along at least two substantially parallel cutting planes perpendicular to the coupling surface.

16. The manufacturing method according to claim 15, wherein: Each of the at least one optical aperture multiplier comprises a first portion having a first set of mutually parallel partially reflective inner surfaces formed by at least a portion of at least some of the coated transparent plates, and a second portion having a second set of mutually parallel partially reflective inner surfaces formed by at least a portion of the plurality of mutually parallel partially reflective inner surfaces.

17. The manufacturing method according to claim 14, further comprising: The cover plate is optically coupled to the second optical structure at one or more of the pair of parallel faces.

18. The manufacturing method according to claim 17, wherein: The cover plate includes a reflective coating.

19. The manufacturing method according to claim 17, wherein: Optically coupling the cover plate to the second optical structure includes bonding the cover plate to one or more of the pair of parallel surfaces.

20. The manufacturing method according to claim 19, wherein: The bonding is performed using an optical glue having a refractive index lower than that of the material used to produce the second optical structure.

21. The manufacturing method according to claim 17, wherein: The cover plate is optically coupled to the second optical structure at one of the pair of parallel faces in facing relationship with the coupling surface, and wherein the cover plate has polarization management properties.

22. The manufacturing method according to claim 21, wherein: The cover plate includes at least one of a wave plate or a polarizer.

23. The manufacturing method according to claim 14, wherein: Obtaining the second optical structure includes generating the second optical structure, and wherein generating the second optical structure includes: bonding together a plurality of transparent sheets coated with a partially reflective coating in a staggered stack; and The offset stack is cut along a pair of parallel cutting planes to produce the second optical structure.

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