Optical system

Abstract

An optical system employs a waveguide comprising: a first set of partially reflective surfaces (“facets”) for progressively redirecting image illumination propagating from an input region toward a second region; and a second set of facets in the second region for progressively decoupling the redirected image illumination toward an observer’s eye. The first set of facets includes at least: a first facet adjacent to the input region, a third facet distant from the input region, and a second facet located on an intermediate plane between the first and third facets. The second facet is located in a sub-region of the intermediate plane such that image illumination propagating from the input region to the third facet passes through the intermediate plane without passing through the second facet.

Description

Technical Field

[0001] This invention relates to optical systems, and more particularly to optical systems for two-dimensionally expanding images from an image projector for display to a user. Prior Technology

[0002] Figure 1A illustrates a near-eye display optical engine comprising an image projector 200 that projects image light with an angular field into a waveguide 204 via a transmission facet (coupled prism) 202T and a vertical aperture 203V. The light propagates within the waveguide and is reflected by total internal reflection. A partial reflector 206 embedded in the waveguide reflects the image from the waveguide toward an observer with an eye center 208 (dashed arrow).

[0003] Figure 1B illustrates an alternative method of coupling the waveguide using a reflective coupling prism 202R with a mirror on its back side.

[0004] Figure 1C schematically shows a front view of a 2D aperture-extended waveguide. Here, an image projector 200 directs an image through a lateral aperture 203L (203V also exists but is not visible from this orientation) into the waveguide 204 via a coupling prism 202. The image ray 220A propagates laterally within the waveguide as it is reflected by total internal reflection (TIR) ​​between the waveguide surfaces. Two sets of facets are used here: set 206L extends the aperture laterally by progressively reflecting the guided image to different guiding directions 220B, while facet set 206V extends the aperture vertically by progressively coupling the image from region 210 on the waveguide to the observer's eye. Summary of the Invention

[0005] The present invention is an optical system for guiding an image illumination incident at a coupling region to an eye-tracking box for viewing by a user.

[0006] According to the teachings of embodiments of the present invention, an optical system is provided for guiding image illumination incident at an insertion region to an eye-tracking box for viewing by a user's eye. The optical system includes a light-guide optical element (LOE) formed of a transparent material, the LOE comprising: (a) a first region containing a first set of mutually parallel planar partially reflective surfaces having a first orientation; (b) a second region containing a second set of mutually parallel planar partially reflective surfaces having a second orientation not parallel to the first orientation; and (c) a set of mutually parallel main outer surfaces extending across the first and second regions such that the first and second sets of partially reflective surfaces are located between the main outer surfaces, wherein the second set of partially reflective surfaces is angled to the main outer surfaces such that a portion of the image illumination propagating from the first region to the second region within the LOE via internal reflection at the main outer surfaces is coupled out of the LOE toward the eye-tracking box, and wherein the first set of partially reflective surfaces is oriented such that a portion of the image illumination from the insertion region propagating through the main outer surfaces via internal reflection at the main outer surfaces is coupled out of the LOE toward the eye-tracking box. A portion of the image illumination propagating within the LOE via internal reflection is deflected toward the second region, wherein the first set of partially reflective surfaces includes: a first partially reflective surface adjacent to the coupling region to contribute to a first portion of the field of view seen by the user at the eye-tracking box; a third partially reflective surface distal to the coupling region to contribute to a third portion of the field of view seen by the user at the eye-tracking box; and a second partially reflective surface located in an intermediate plane between the first and third partially reflective surfaces to contribute to a second portion of the field of view seen by the user at the eye-tracking box, wherein the second partially reflective surface is deployed in a sub-region of the intermediate plane such that the image illumination propagating from the coupling region to the third partially reflective surface and contributing to the third portion of the field of view seen by the user at the eye-tracking box passes through the intermediate plane without passing through the second partially reflective surface.

[0007] According to another feature of an embodiment of the invention, the coupling region includes a coupling prism having a first planar surface that is a continuation of one of the main outer surfaces in the first region, and the coupling prism having a thickness dimension greater than the LOE, measured perpendicular to the main outer surface.

[0008] According to another feature of an embodiment of the invention, the coupling prism presents a transition line as LOE between the coupling surface and the coupling prism, the coupling surface defining the optical aperture of the coupling prism in a dimension parallel to the main outer surface, and the transition line defining the optical aperture of the coupling prism in a dimension perpendicular to the main outer surface.

[0009] According to another feature of an embodiment of the invention, the first set of partial reflective surfaces further includes at least one partial reflective surface located within the volume of the coupled prism.

[0010] According to the teachings of embodiments of the present invention, an optical system is also provided for guiding image illumination incident at a coupling region to an eye-tracking box for viewing by a user's eye. The optical system includes a light-guiding optical element (LOE) formed of a transparent material, the LOE comprising: (a) a first region including a first set of mutually parallel planar partially reflective surfaces having a first orientation; (b) a second region including a second set of mutually parallel planar partially reflective surfaces having a second orientation not parallel to the first orientation; and (c) a set of mutually parallel main outer surfaces extending across the first and second regions such that the first and second sets of partially reflective surfaces are located between the main outer surfaces, wherein the second set of partially reflective surfaces is angled to the main outer surfaces such that light passing through the main outer surfaces... A portion of the image illumination propagated from the first region to the second region by internal reflection within the LOE is coupled outward from the LOE toward the eye-tracking box, and wherein a first set of partially reflective surfaces is oriented such that a portion of the image illumination propagated within the LOE by internal reflection from the coupling region through the main outer surface is deflected toward the second region, wherein the coupling region includes a coupling prism having a first planar surface that is a continuation of one of the main outer surfaces in the first region, the coupling prism having a thickness dimension greater than the thickness of the LOE, measured perpendicular to the main outer surface, and wherein the coupling prism presents a transition line between the coupling surface and the coupling prism as the LOE, the coupling surface defining the optical aperture of the coupling prism in a dimension parallel to the main outer surface, and the transition line defining the optical aperture of the coupling prism in a dimension perpendicular to the main outer surface.

[0011] According to another feature of an embodiment of the invention, the first set of partial reflective surfaces further includes at least one partial reflective surface located within the volume of the coupled prism.

[0012] According to the teachings of embodiments of the present invention, an optical system is also provided for guiding image illumination incident at a coupling region to an eye-tracking box for viewing by a user's eye. The optical system includes a light-guiding optical element (LOE) formed of a transparent material, the LOE comprising: (a) a first region including a first set of mutually parallel planar partially reflective surfaces having a first orientation; (b) a second region including a second set of mutually parallel planar partially reflective surfaces having a second orientation not parallel to the first orientation; and (c) a set of mutually parallel main outer surfaces extending across the first and second regions such that the first and second sets of partially reflective surfaces are located between the main outer surfaces, wherein the second... The first set of partially reflective surfaces is angled to the main outer surface such that a portion of the image illumination propagating from the first region to the second region within the LOE via internal reflection at the main outer surface is coupled out from the LOE toward the eye-tracking box, and wherein the first set of partially reflective surfaces is oriented such that a portion of the image illumination propagating within the LOE via internal reflection at the main outer surface from the coupling region is deflected toward the second region, wherein the coupling region includes a coupling prism having a first planar surface that is a continuation of one of the main outer surfaces in the first region, the coupling prism having a thickness dimension greater than the thickness of the LOE, measured perpendicular to the main outer surface, and wherein the first set of partially reflective surfaces also includes at least one partially reflective surface located within the volume of the coupling prism.

[0013] According to another feature of an embodiment of the invention, the coupling prism presents a transition line as LOE between the coupling surface and the coupling prism, the coupling surface defining the optical aperture of the coupling prism in a dimension parallel to the main outer surface, and the transition line defining the optical aperture of the coupling prism in a dimension perpendicular to the main outer surface.

[0014] According to another feature of an embodiment of the invention, the coupling prism is bonded to the LOE at an edge surface of the LOE. Alternatively, the coupling prism may be bonded to one of the main outer surfaces of the LOE. Simple Explanation of the Diagram

[0015] The invention is described herein by way of example only with reference to the drawings, in which: Figures 1A and 1B above are schematic side views of a conventional waveguide-based near-eye display illustrating two geometries used to couple image illumination into the waveguide; Figure 1C above is a front view of a conventional waveguide-based near-eye display that uses a first set of partially reflective inner surfaces and a second set of partially reflective inner surfaces to extend the optical aperture of an image projector in two dimensions; Figure 1D is a schematic isometric view of a waveguide similar to that in Figure 1C and corresponding to Figure 5A in publication WO 2020 / 049542 A1; Figures 2A to 2C are respectively isometric views, top views, and side views representing the angles of image propagation through an optical system according to the teachings of the present invention; Figure 3A is a schematic front view of a light-guiding optical element (LOE or waveguide) constructed and operated according to aspects of the present invention, showing the propagation of image illumination from the coupling region to a first set of partially reflective surfaces (facets) and from the first set of facets to a second set of facets; Figure 3B is a view similar to Figure 3A, showing the theoretical trajectory of the plane position required to provide a field of view (FOV) for a single viewpoint; Figure 3C is a view similar to Figure 3B, showing the corresponding set of trajectories for providing FOV on a small plane position in an eye-motion box (EMB) at an allowed viewing position; Figure 3D is a view similar to Figure 3A, showing the position and size of the small planes required to traverse the trajectory shown in Figure 3C; Figure 3E is a view similar to Figure 3C, in which the trajectory is further increased according to the geometric requirements generated by using a first set of small planes at an inclined angle; Figure 3F is a schematic representation of Figure 3D in which the regions contained by the small planes are demarcated by corresponding polygons, and the first group of small planes is demarcated by concave polygons in the LOE. Figure 3G is a view similar to Figure 3F, in which a concave polygon containing a first set of facets is subdivided into multiple non-concave blocks or patches; Figure 3H is a schematic isometric view showing how these blocks are assembled to produce the structure of Figure 3G for subsequent slicing to form multiple LOEs; Figure 4A is a view of an exemplary size, similar to Figure 3A, illustrating an implementation for generating a rectangular field of view with the angular dimensions shown in Figure 4B; Figure 4B shows the rectangular field of view with the angular dimensions in Figure 4A; Figure 4C is a view, similar to Figure 3A, illustrating an exemplary dimension for generating a trapezoidal field of view with the angular dimensions shown in Figure 4D; Figure 4D shows the trapezoidal field of view with the angular dimensions in Figure 4C; Figure 5A is a view similar to Figure 4A, showing an image projector and a coupling prism for introducing image illumination into the LOE; Figure 5B is a schematic isometric view of the coupling prism of Figure 5A; Figure 5C is a side view of the coupling prism shown in Figure 5A, illustrating the dimensions required for an exemplary embodiment of the present invention; Figure 5D illustrates a variant implementation of the present invention using a coupling prism attached to the main outer surface of the LOE; Figure 6A is a schematic front view, similar to Figure 5A, illustrating the use of an integrated laser scanning image projector integrated with a coupling prism; Figure 6B is a schematic side view of an integrated laser scanning image projector integrated with the coupling prism of Figure 6A; Figure 7A is a schematic side view of a coupling arrangement employing a tilted reflector and a coupled prism with an external collimating optics; Figure 7B is a view similar to Figure 7A, but with a reduced size and a combination of tilted reflector coupling arrangement and coupled prism; Figure 7C is a view similar to Figure 7A, employing a polarization beam splitter and integrating reflective collimating optics into a reflective coupling arrangement; Figure 7D is a view similar to Figure 7C but using an external collimating optics; Figure 8A is a view similar to Figure 5A, but in which the coupled prism is integrated with a portion of the waveguide; Figure 8B is a schematic isometric view of the coupling prism of Figure 8A; Figure 9A is a schematic side view of the coupling prism of Figure 8A, which is implemented as a coupling prism joined to the LOE at the edge surface of the LOE; Figures 9B and 9C are schematic isometric views of Figure 9A showing a coupling prism that includes all or part of the partial reflective facets within the prism, respectively; Figure 9D is a schematic side view of the coupling prism of Figure 8A, which is realized as a coupling prism bonded to one of the main outer surfaces of the LOE; Figures 9E and 9F are schematic isometric views of Figure 9D showing a coupling prism that includes all or part of the partial reflection facets within the prism, respectively; Figure 10A is a side view, similar to Figure 2C, showing the angle representation of two specific points within the field of view of the projected image; Figure 10B is a partial view, similar to Figure 4A, showing the image light propagation path corresponding to the two points in Figure 10A; Figures 10C and 10D are side views of the coupling prism, indicating the incident angles at the two field points and the corresponding desired positions of the first reflecting planes that the field points should encounter; Figures 11A to 11C are views, similar to Figures 7A, 7C, and 7D respectively, illustrating the implementation of these geometries having partially reflective facets within the coupled prism; Figure 11D is a view similar to Figure 6B, illustrating the implementation of this geometry with a partially reflective facet within the coupled prism; Figure 12A is a schematic isometric view of a series of plates having partially reflective coatings selectively deployed in patterns according to different planes of the LOE according to Figure 3D, for assembly according to the production method of the present invention; Figure 12B is a schematic isometric view of a stack of plates formed by joining a series of plates from Figure 12A together; Figure 12C is a schematic isometric view of a block formed by slicing the stack of Figure 12B along the indicated dashed lines; Figure 12D is a schematic isometric view of a portion of the LOE formed by slicing the block of Figure 12C along the indicated dashed lines; Figure 13 is a schematic side view of the coupling structure using air gap and mirror; Figures 14A and 14B are views similar to Figures 2A and 2C, respectively, showing image propagation through the optical system in the case of a first set of partially reflective surfaces with an inclined orientation; Figure 14C is a view of an implementation of a LOE similar to Figure 3F, optimized for image propagation as described in Figures 14A and 14B; Figure 15 is a schematic side view of a side-coupled structure using a beam splitter to fill the waveguide with the incident image and its conjugate; Figure 16A is a side view showing the angle of image propagation through the second region of the LOE according to a modified implementation of the present invention using a highly inclined second set of partially reflective surfaces; Figure 16B is a schematic side view of the second region of the LOE realized according to the optical geometry of Figure 16A; Figure 16C is a graph schematically indicating the preferred angle dependence of the reflectivity of the facet for the implementation of Figure 16B; Figure 17A is a schematic isometric view of a plate with a selectively deployed partial reflective coating, similar to the plate in Figure 12A; Figure 17B is an enlarged schematic side view showing the coated area achieved using steep edges; Figure 17C is a schematic illustration of using a raised mask to generate a coating with gradually varying thickness in edge regions; Figure 17D is a schematic illustration of depositing a multilayer coating with gradually varying thickness at the edge regions using the principle of Figure 17C; Figure 17E is a schematic illustration of generating a complementary transparent coating in an area not coated by the first process using a second raised mask; and Figure 17F is a schematic side view showing a partially reflective area produced by the sequence of the coating process described with reference to Figures 17D and 17E. Implementation

[0016] The present invention is an optical system for guiding an image illumination incident at a coupling region to an eye-tracking box for viewing by a user.

[0017] As introduced, in the context of a near-eye display of the type shown in Figure 1C, it has been found that particularly advantageous geometric properties can be provided by illuminating the image into the waveguide at a “shallow angle,” and in particular, the size required for a given field of view is minimized. This means that all image illumination is incident only on one side of both the first set of facets and the second set of facets. Generally, in the shallow-angle implementation, at least a portion of each image lies within approximately 15 degrees of the plane from the outer surface of the waveguide, and more preferably within approximately 10 degrees. This produces a shortened optical path from the image projector to the observer's eye, and thus also allows for a reduction in the size of the optical components for a given field of view. The present invention relates to several aspects of shallow-angle implementations of such displays, which present specific design challenges, particularly with respect to the design challenges of the coupling structure. However, it should be noted that the various aspects of the invention described herein are not limited to shallow-angle implementations and can also be applied to other implementations.

[0018] Figures 2A to 2C show the angular polarity representation of an image propagating in a waveguide according to the invention. Figure 2A shows an isometric view, Figure 2C shows a side view, and Figure 2B shows a top view (relative to Figure 2A) corresponding to the view from the front of the waveguide.

[0019] The waveguide has total-internal-reflection (TIR) ​​boundary circles 228, indicating that the images within these circles are not affected by TIR and will be coupled out of the waveguide.

[0020] Image 220A1 is coupled into the waveguide and propagated back and forth to 220A2 via TIR. These images propagate along the waveguide along very shallow tracks, with the shallowest portion of the image only at 7 degrees to the waveguide plane (shown as angle 221 in Figure 2C). In this implementation, facet 224 (equivalent to 206L in Figure 1C) is perpendicular to the waveguide and thus reflects images 220A1 and 220A2 directly onto 220B1 and 220B2, respectively. As images 220B1 and 220B2 propagate along the waveguide, they are coupled via TIR. In the second part of the LOE, facet 226 (equivalent to 206V in Figure 1C) couples image 220B2 from the waveguide onto image 220C facing the observer.

[0021] As a non-limiting example, the illustrations shown herein primarily relate to an image with an aspect ratio of 4:3 and a diagonal field of 70 degrees incident on a waveguide with a refractive index of 1.6. The design shown here generates a complete image (including exit pupil distance, eye radius, and edges) at the center of the eye, 35 mm away from the waveguide. Those skilled in the art can readily implement these implementations for different fields of view and aspect ratios based on the description herein.

[0022] One aspect of the invention relates to optimizing the deployment of partial reflective surfaces (or “facets”) in the first portion of a waveguide responsible for the first-dimensional optical aperture extension. In an earlier patent application published as WO 2020 / 049542 A1 (“'542 disclosure”), it was proposed to selectively arrange facets within an envelope surrounding facets required for delivering image illumination to an eye-tracking box from which the image is to be viewed.

[0023] An example of the final deployment of the facet is shown in Figure 5A of this disclosure, which is reproduced herein as Figure 1D. In this implementation, an optical system for guiding image illumination incident at coupling region 15 to eye-tracking box 26 for viewing by the user's eye employs a light-guiding optical element (LOE) 12 formed of a transparent material, the light-guiding optical element having: a first region 16 comprising a first set of mutually parallel planar partially reflective surfaces 17 having a first orientation, and a second region 18 comprising a second set of mutually parallel planar partially reflective surfaces 19 having a second orientation, the second orientation not parallel to the first orientation. A set of mutually parallel main outer surfaces 24 extends across the first and second regions such that the first and second sets of partially reflective surfaces are located between the main outer surfaces. The second set of partially reflective surfaces 19 is angled to the main outer surfaces 24 such that a portion of the image illumination propagating from the first region to the second region within the LOE via internal reflection at the main outer surfaces is coupled out of the LOE from coupling region 28 toward eye-tracking box 26. The first set of partially reflective surfaces 17 is oriented such that a portion of the image illumination from the coupled region, propagating within the LOE via internal reflections at the main outer surface, is deflected toward the second region.

[0024] According to the teachings disclosed in '542, certain portions of the first region 16 of the LOE outside the envelope of the useful facets are implemented as an optical continuum (i.e., without partially reflective inner surfaces), thereby reducing unwanted ghosting reflections. However, within the envelope of the convex polygon, the facets are implemented to fill the entire width of the convex polygon, as shown in the figure. Therefore, a portion of the field of view reflected from a facet located on the far side of the coupling region passes through a long series of partially reflective facets before reaching the facet that delivers that portion of the field of view to the eye-tracking box.

[0025] According to one aspect of the invention, the region of the facet required to deliver a given field of view to the eye-tracking box is further refined to generate a concave polygon defining the desired facet position, thereby removing a portion of the intermediate facet that would otherwise unnecessarily cause image illumination attenuation of the portion of the field guided to provide the field reflected by the facet furthest from the coupling region.

[0026] Therefore, as shown in Figure 3D, the first set of partially reflective surfaces (labeled here as 206L) includes: a first partially reflective surface 17A, which is close to the coupling region 240, to contribute to a first portion of the field of view (FOV) seen by the user at the eye-tracking box; a third partially reflective surface 17C, which is far from the coupling region, to contribute to a third portion of the FOV seen by the user at the eye-tracking box; and a second partially reflective surface 17B, which is located in the intermediate plane 22 between the first and third partially reflective surfaces, to contribute to a second portion of the FOV seen by the user at the eye-tracking box. In the example shown in Figure 3D, the first partially reflective surface (planet) 17A contributes to the right side of the FOV, the third partially reflective surface (planet) 17C contributes to the left side of the FOV, and the second partially reflective surface (planet) 17B contributes to the central region of the FOV. A particular feature of this aspect of the invention is that the second part of the reflective surface 17B is deployed in a sub-region of the intermediate plane 22 such that the image illumination of the third part of the field of view that propagates from the coupling region to the third part of the reflective surface (arrow 23) and contributes to the user’s field of view at the eye tracker passes through the intermediate plane 22 without passing through the second part of the reflective surface 17B.

[0027] In this context, it should be noted that the terms “near,” “far,” and “middle” are used herein to indicate relative position with respect to the point or region of interest (in this case, coupled region 240), and refer to a plane that is relatively closer (closer) to the coupled region or relatively farther (farther) from the coupled region, or a plane that is “towards the middle” (central), without necessarily indicating the nearest, farthest, or central plane according to any specific geometric definition.

[0028] A conceptual description will now be provided to facilitate a better understanding of the geometrical optical considerations that enable preferred design parameters for a given implementation of this aspect of the invention. It should be noted that this description is given for informational purposes only, but the utility of the claimed invention does not depend on the accuracy of any aspect of this description, and effective and advantageous implementations of the claimed invention can alternatively be achieved through empirical methods.

[0029] Figure 3A shows a front view of a few selected beams of a projected image with parameters corresponding to the exemplary FOVs mentioned above. Solid lines represent beams incident laterally into the waveguide, and dashed lines represent beams after lateral aperture expansion and reflection as the beam propagates vertically. It should be noted throughout this document that any example describing lateral expansion followed by vertical expansion can be changed to vertical expansion followed by lateral expansion without inherent structural alterations. This can be simply illustrated by rotating the above diagram by 90 degrees.

[0030] All beams are emitted from the entrance pupil in coupling region 240. The beams propagate within the waveguide until they are reflected by a set of parallel embedded reflectors 206L (facets). It is assumed that the facets in this figure are perpendicular to the outer surface of the waveguide. Therefore, each line (solid followed by dashed) represents a different transverse section of the image field projected into the observer's eye. The vertical field of each section is illuminated by multiple overlapping beams (as viewed from the front) that propagate at different angles (as seen from the front) by reflection via TIR (such internal reflection is shown in the side view of Figure 1A).

[0031] For the purpose of simplifying the geometric analysis, it is initially assumed that only the entire lateral field is needed to illuminate the center of the eyeball 208. Theoretically, this can be achieved by placing infinitesimally small lateral planes 206L infinitely close to each other along the trajectory denoted as 244A in Figure 3B. However, the requirement to accommodate the lateral displacement of the eyeball center (e.g., due to variations in interpupillary distance between users) determines the displacement of curve 244A. Figure 3C schematically shows the curves at three lateral positions of the eyeball center 208: 244A, 244B, and 244C. To cover the required width of the eye-tracking box, the planes need to be widened.

[0032] Other requirements include: ● There is a finite minimum distance between the planes (i.e., the planes cannot get infinitely close). ● The aperture size cannot be too small; ● The small plane must project continuous reflections toward the vertically extended small plane 206V.

[0033] Figure 3D shows a finite-sized facet 206L suitable for the conditions described above. The length of the facet can vary depending on the facet spacing and other optical parameters such as the refractive index, the size of the projected field, and the position of the image coupling region (intrusion) 240.

[0034] With the lateral extension facet 206L at an angle to the main outer surface of the LOE, the image is projected into a waveguide that rotates relative to the waveguide's axis, and reflections from facet 206L rotate the image to the desired orientation. Therefore, the curve used for projection onto the eye center 208 will look like Figure 3C, and when further considering the extension required for the lateral eye-tracking box, the curve looks like Figure 3E, which shows a further multiplication of curves 244A, 244B, and 244C. Therefore, this requires a facet that is slightly wider than the corresponding implementation with orthogonal facets used for the first extension.

[0035] Some advantages of this aspect of the invention can be better understood with reference to FIG3F. A region of laterally extended facets is described at SL, while the “recessed” region above this region is SD, and the region of vertically extended facets is SV. Due to the concave polygonal form of region SL, light propagating laterally from the coupling region (entrance) 240 propagates primarily in the transparent region SD before being reflected downwards in region SL. Propagation in the transparent region reduces the loss of image illumination through reflections into undesired directions, thereby improving waveguide efficiency. Furthermore, there is no undesired reflection of the scene from the facets in region SD, thus substantially reducing flicker and ghosting from the waveguide.

[0036] Figures 3G and 3H illustrate one possible method for generating a region (laterally extended section) SL with a “recessed” region SD. The portion including regions SD and SL is subdivided into blocks indicated by the coarse outline in region designation 300 in Figure 3G. Figure 3H shows how such a structure can be assembled from a transparent prism 302 with appropriate facet angles and three plates (shown as lines along the plates) with appropriate small facet angles, the three plates together abutting against the respective surfaces of the prism 302 and against each other to form the assembled structure shown. This structure is combined with additional transparent prisms and vertically extended portions of the LOE to generate an integral structure.

[0037] Alternatively, the combined prism and plate can be sliced, or it can be first attached to another stack to be sliced ​​together to generate a waveguide having all of its parts.

[0038] The waveguide dimensions described above are shown in Figure 4A, resulting in the image field angular size shown in Figure 4B. Note that the most laterally extended beam 250 illuminates only the lower corner of the image, thus requiring a large waveguide area and contributing only to a small portion of the image. In some applications, providing a non-rectangular FOV, and particularly a trapezoidal image field as shown in Figure 4D, is acceptable or even advantageous. In this case, an image with the same total area as Figure 4B is shown (shown in dashed lines in Figure 4D for comparison), but distributed in a trapezoidal pattern, where the field at the top is wider than the field at the bottom. The LOE generating this FOV is shown in Figure 4C with corresponding dimensions. In this case, the lateral edge beam 252 illuminates all fields vertically (entering the page at correspondingly different angles), thus making more efficient use of the LOE size. Therefore, the waveguide dimensions of Figure 4C are substantially smaller than those of Figure 4A, as shown by exemplary dimensions for the same total FOV area. The following description illustrates other aspects of the invention in a non-limiting exemplary context of the construction in Figure 4A, but it should be understood that constructions such as the one in Figure 4C can be implemented using the same principles.

[0039] Imaging a shallow image into the waveguide requires a relatively large coupling prism 202. Figure 5A shows a waveguide with a lateral aperture (incident pupil) 203L and a coupling prism 202M to scale. An image projector 200 is schematically shown. Figure 5B is an isometric view of the coupling prism 202M with a vertical aperture 203V and a lateral aperture 203L, both located in the same plane to define a rectangular aperture. Figure 5C shows a side view of the coupling prism 202M, which requires a 14 mm long coupling prism for a 1.7 mm thick waveguide. This coupling prism is designed to couple light from all field angles into the waveguide. A portion of the beam 262 is reflected from the bottom of the prism before entering the waveguide 204 through the aperture (pupil) 203V. The height of the coupling prism 202M above the waveguide is 6.4 mm, which is acceptable in many applications. However, the size of the image projector 200 required to project an image through the coupling prism 202M also takes up space and volume, and would be unacceptable in many applications.

[0040] The coupled prism 202M (and other prisms described herein) preferably has a lower surface parallel to the waveguide surface for uniform reflection, while the upper and side surfaces do not require specific optical properties, and therefore their shapes may differ from those shown in these figures.

[0041] Figure 5D shows an alternative configuration where the coupling prism 202L is located above the waveguide and the incident pupil is an alternative to prism 264. In this case, the prism and the required projector are larger than those in Figures 5A to 5C, making this configuration suboptimal.

[0042] Figures 6A and 6B illustrate one option for reducing the overall size of the coupling arrangement and the image projector, showing the integration of the image projector with the coupling prism. The scanning laser image projector is shown here by way of non-limiting example, but the same principle can be achieved using an image projector based on another type of image generator, such as a liquid crystal on silicon (LCOS) spatial light modulator or a micro-light emitting diode (LED) image generator.

[0043] Figure 6A shows the coupling prism 202P attached to waveguide 204. Figure 6B shows a side view of the integrated (embedded) image projector. Laser 270 guides a polarized beam onto scanning mirror 272, which scans across the intermediate image plane of the micro-lens array (MLA) or diffuser 274. The scanned light passes through the diffuser and is reflected from polarization beam splitter 276 onto collimating mirror 278 (combined with a quarter-wave plate). The reflected light passes through polarization beam splitter (PBS) 276 and enters the coupling prism 202P. Thus, the coupling prism also serves as part of the PBS 276. A portion of the light enters the waveguide directly, while a portion is reflected by the lower surface 279 before entering the waveguide, thereby filling the aperture of the waveguide with the image and its conjugate.

[0044] Incidentally, whether the PBS arrangement is shown herein as reflecting and then transmitting light sequentially, or vice versa, it should be understood that the appropriate placement of a half-wave plate (for single transmission) or a quarter-wave plate (for double transmission) is necessary to achieve the polarization rotation required for the stated function. Polarization rotation elements will not be mentioned in every case.

[0045] Figures 7A through 7D illustrate alternative configurations for combining an image projector with a coupling prism. Figure 7A shows light from an image generator (not shown, but as previously mentioned, it could be a scanning laser, LCOS, or others) being collimated by a refractive lens 280 (the beams in the figure originate from different field points and are therefore not parallel), entering prism section 282, and being reflected by mirror 284 into coupling prism (prism section) 202Q and then into waveguide 204. In this configuration, prism section 282 and coupling prism 202Q can be combined into a single prism, as shown in Figure 7B. Furthermore, in this case, light polarization is not required.

[0046] The structure of Figure 7B uses the same reflector structure as Figure 7A, but with a smaller prism. Here, for similar output parameters, similar to the coupled prism 202M in Figure 5C, the prism length is approximately 14 mm. However, the height will be only 3.2 mm, half that of the coupled prism 202M. As with all the prisms described herein, the upper (non-reflective) surface of prism 283 is preferably absorptive. It is drawn here according to the upper beam 260 (defined in Figure 5C), but since the upper surface is not optically important, it can be higher and / or have other shapes.

[0047] The prism may also be provided with a coupling structure including a low-refractive-index portion on its lower surface equivalent to element 286 or 228 described below with reference to Figures 7C and 7D. This interface can be used to attach to a PBS as an image projector.

[0048] Figure 7C illustrates the incident divergent polarized light corresponding to the image (from an MLA, scanning laser, LCOS, or other image generator) passing through interface 286 into prism (PBS section) 290 and reflected by PBS 292 onto reflective collimating lens 294. The reflected collimated light passes through PBS 292 into coupling prism 202Q and then into waveguide 204. In this configuration, some of the light is reflected by the lower portions of prism 290 and coupling prism 202Q, therefore these surfaces need to have good image quality and be continuous. Interface 286 can be air or a low-refractive-index medium (relative to prism 290) such that TIR occurs for the light reflected from reflective collimating lens 294.

[0049] Figure 7D shows an arrangement similar to that of Figure 7C, but with external optics for light collimation (e.g., a refractive lens 296) and a flat reflector 298.

[0050] Turning now to Figures 8A and 8B, these figures illustrate an alternative construction according to another aspect of the invention, wherein the coupling prism is integrated with a portion of the waveguide, rather than as an extension as shown in Figure 5A. Figure 8A shows the coupling prism 202Y (dashed area) on top of the waveguide 204. Thus, the image projector (generator) 200 is positioned closer to the waveguide and has a smaller size. All light propagating in the waveguide continues to emerge from the coupling region (point) 240, so the lateral aperture 203L2 is located in the same position as in the previous embodiment. However, here the vertical aperture 203V is located at the end of the prism, where the thickened portion of the prism meets the main outer surface of the main portion defining the LOE. Figure 8B shows the shape of the coupling prism in an isometric view. The two apertures 203L2 and 203V2 have the same width as previously described, but due to the separation of positions, the prism extends vertically at aperture 203L2.

[0051] As is evident in Figure 8A, some of the facets (represented here as 206A and 206B) are located within the prism. Figures 9A through 9F illustrate various possible implementations of these facets in prism 202Y. For clarity, facets located within the main portion of the LOE are omitted here.

[0052] Figure 9A shows a prism 202Y attached to the edge of the waveguide, and Figure 9B shows the placement of the facets in the prism in an equidistant manner. However, since it is not necessary for the facets to reflect light across the entire width of the prism (as can be seen in Figure 8A, which shows that the required width of facets 206A and 206B is finite), Figure 9C shows the reflected portion (shaded area) of only a part of the corresponding plane within the prism.

[0053] Figure 9D shows an alternative construction in which the prism 202Y is formed by attaching a block of the corresponding shape to the top of the waveguide 204 (the facet in 204 is not shown). In Figure 9E, the same structure of the facet over the entire cross-section of 202Y above the LOE thickness is shown, while in Figure 9F, only the reflection area is realized as a shaded area corresponding to only the optimal desired area.

[0054] In some cases, the aforementioned integrated image projector (Figures 6A to 7D) can be combined with the LOE-integrated coupling prism of Figures 8A to 9F. Some geometric considerations in such an implementation are illustrated with reference to Figures 10A to 10D.

[0055] Figure 10A shows a side view of the angular distribution of markings for two field points, identical to those in Figure 2C, but with two field points associated with facets 206A (circular) and 206B (square). The same field points are shown in Figure 10B.

[0056] Figure 10C shows a side view of the waveguide-overlapping coupling prism, where the shaded area represents the preferred location of the facet associated with 206A, and Figure 10D shows the preferred location of the facet for 206B. PBS 292 is shown here for reference. It is evident that the preferred location of the facet in the overlapping coupling prism should be above the PBS plane. Implementing the facet before the PBS plane will result in distortion of the transmitted image.

[0057] Figures 11A to 11D are side views illustrating the implementation of the facet of the coupling prism incorporating the projector optics. Figures 11A, 11B, and 11C show the integration of the facet portion 202T (marked as shaded area) into another configuration similar to those in Figures 7A, 7C, and 7D, respectively. 3D representation remains as described with reference to Figures 10A to 10D.

[0058] Figure 11D is similar to Figure 6B, and shows that when the PBS orientation is reversed, the small facet portion 202T2 is preferably implemented only partially behind the PBS plane. Therefore, the coupling prism will extend slightly further beyond the lateral aperture 203L2 (shown in Figures 8A and 8B).

[0059] Incidentally, the deployment of the small planar portion 202T2 shown in Figure 11D is also suitable for the construction of waveguide structures using Figures 4C and 4D.

[0060] Turning now to Figures 12A to 12D, as an alternative to the production process shown above with reference to Figures 3G to 3H, the facet patterns of Figure 3D or 3F can be produced based on stacking and slicing selectively coated plates. In this case, as shown in Figure 12A, plates are coated with a predetermined pattern, which shows a set of plates from the front side 300F coated with the predetermined pattern 302F. These patterns have the width and position of the desired coated facets as shown in 112. These patterns are preferably produced by masking the uncoated portions of the waveguide during coating. Alternatively, only other portions of the plate facets in 304F can be coated with a non-reflective coating to maintain a flat surface or to keep the phase of the transmitted light through 304 equal to the phase of the transmitted light through prism 302.

[0061] Figure 12B shows a stack formed by joining partially coated plates together, with dashed lines indicating slice planes on the stack. Figure 12C shows a slice with a side view of plate 300S and reflective pattern 302S. Another slice is completed as shown by the dashed lines in Figure 12C to generate the final upper portion of Figure 12D, which corresponds to the upper portion of the LOE in Figure 3D.

[0062] It should be noted that the order of the slices can be changed. It should also be understood that the illustrations in Figures 12A to 12D are highly schematic and typically use a larger number of slices.

[0063] Reducing the refractive index of the coupling prism 202M can also be used to reduce the prism size and thus make the system more compact. Figure 13 shows an extreme case of this concept where the coupling prism 202M is replaced by a mirror 310 and an air gap in the same plane as the lower waveguide plane 312. Light from the projection optics 308 is guided to the vertical entrance 306 of the waveguide 204 and the mirror 310. Due to the lower refractive index of the air gap, the angle of the beam changes, and therefore the length of the mirror is shorter than that of the coupling prism 202M. The angle of the lower beam 262 is now 11.5 degrees instead of the previous 7 degrees. Therefore, the mirror length is now 8.5 mm instead of 14 mm in Figure 5C. The angular distribution of the beam as it enters the waveguide is shown in Figure 5C. The mirror can overlap with the waveguide for mechanical attachment.

[0064] A conceptually similar approach using low-refractive-index materials can be achieved using low-refractive-index glass prisms. When using low-refractive-index glass prisms, some dispersion caused by the angle of incidence of light entering the vertical entrance (plane) 306 can be compensated.

[0065] In the embodiments detailed above, the facet 206L used for the first set of facets is orthogonal to the main outer surface of the LOE, as detailed in Figures 2A to 2C. In an alternative set of embodiments shown with reference to Figures 14A to 14C, the first set of facets is implemented using a facet 336 at an angle. Figure 14A shows an equidistant angular representation of such a system for transmitting shallow-angle images, while Figure 14B shows a corresponding partial side view of this angular representation. This non-limiting example employs a trapezoidal FOV equivalent to the minimum-size image shown in Figures 4C and 4D, although this structure can clearly also be used for a rectangular FOV.

[0066] In this structure, the initial laterally propagating image 334A1 is coupled to image 334A2 via TIR reflection. Only image 334A2 is redirected towards the second region of the LOE as image 334B1 via a small plane 336 at an angle relative to the waveguide surface. As is known in the art, the small plane 336 is preferably coated with a multilayer dielectric coating to provide the desired degree of partial reflectivity for the incident angle range corresponding to image 334A2 (as in all the above embodiments), while being substantially transparent for the incident angle range corresponding to image 334A1, to minimize energy loss and the formation of undesirable reflections. As image 334B1 propagates at a shallow angle along the second region of the waveguide, image 334B1 is coupled to image 334B2 via TIR. Image 334B2 is then coupled out as 334C via small plane 338 (shown only in FIG. 14A) in a manner equivalent to small plane 226 of FIG. 2A to 2C.

[0067] Figure 14C shows the waveguide coverage area equivalent to that in Figure 4C, where the shaded area 340 is the optimal area for the first set of facets 336, and the area 342 is the optimal area for the output coupling facets 338.

[0068] The various coupled prism arrangements described above are configured to couple both the image and its conjugate into the LOE to "fill" the waveguide with the image. A particularly attractive alternative for injecting shallow-angle images into the waveguide is to inject the image directly into the waveguide, as shown in Figure 15. To fill the waveguide 370 with the injected image and its conjugate, the waveguide 370 has a coupled region 372, which has a partial reflector 374 along the central plane of the waveguide. The partial reflector 374 is most preferably implemented as a 50% reflector, preferably insensitive to angle and achromaticity, for example, a partially silvered surface.

[0069] Figure 15 shows three beams associated with the lowest point in the field, and these three beams are therefore the shallowest beams of image illumination. The lower beam (solid arrow) passes through collimating optics 376 and coupling prism 378 and enters the waveguide. After one reflection, the lower beam undergoes partial reflection through partial reflector 374 and is split into two beams. The central beam (dashed line) is split at the entrance, and the upper beam (dotted line) is split in half along the coupling region (combiner) 372. Clearly, after the beams are split (thus separating the image illumination between the image and its conjugate), the waveguide is uniformly illuminated. Therefore, a uniform image is desired after the light is coupled out.

[0070] If the partial reflector 374 has 50% reflectivity and 50% transmittance, then the waveguide will be uniformly illuminated for a length equivalent to that of Figure 5C (14 mm in this example). In this configuration, the aperture of the illuminating optics 376 is very small because the optics are almost adjacent to the entrance of the waveguide, resulting in a small thickness of the optical element.

[0071] Turning now to Figures 16A through 16C, this illustrates an alternative scheme for coupling the image in the second region of the LOE toward the eye-tracking box for viewing by the user's eye. The angular representation in Figure 16A is similar to that in Figure 2C, but in this case, the output coupling plane 390 has a steep angle. Therefore, image 220B1 is coupled out as 220C (instead of 220B1 in Figure 2C). In this configuration, image 220B can be higher and is not limited by the angle of plane 390.

[0072] Figure 16B schematically illustrates how such a configuration would look in real space. As the beam propagates downwards (in this figure), it is partially reflected downwards by the facets and exits the waveguide. In such a configuration, closely spaced facets are preferred to ensure a uniform image.

[0073] Figure 16C schematically illustrates the preferred reflectivity for a facet constructed in this way. Here, low reflectivity is desired at low incident angles (nearly vertical), while higher reflectivity is desired at higher angles (for output coupling). Similarly, this characteristic can be readily achieved here using a properly designed multilayer dielectric coating, as is known in the art.

[0074] Turning now to Figures 17A through 17F, the various preferred embodiments described herein require the selective application of a reflective coating only to a portion of a plate, which is then assembled into a stack, from which partial or complete LOEs are sliced. Due to the physical discontinuities in the coating as shown in the schematic cross-section of Figure 17B, partial coating on the small facets shown in Figure 17A may introduce scattering effects at the edges of the coating. Additionally, this mechanical discontinuity can generate mechanical stress on the plates during stacking (as shown in Figure 12B). Figures 17C through 17F illustrate preferred manufacturing methods according to aspects of the invention for overcoming these limitations.

[0075] Figure 17C illustrates the principle of coating characteristics when mask 394 is placed close to the front (plate surface) 300F but slightly spaced apart from it. When coating is applied (thick arrow), it coats the plate without a mask but close to it, creating a gradual decrease in coating thickness around the edge of mask 396. Figure 17D schematically illustrates how this characteristic can be used to create a gradual decrease ("tail") in the coating pattern 302F around the desired area.

[0076] For thin coating thicknesses, this gradually thinning structure may be sufficient. For thicker coatings, it may be advantageous to use a second mask (Fig. 17E) on pattern (area) 302F and apply a complementary transparent coating 398 next to the reflective pattern (area) 302F, as shown in Fig. 17F. It should be noted that the mask of Fig. 17E is generally not an exact inversion of the mask of Fig. 17D, as it preferably adds an amount around the boundary corresponding to the trailing area (which can be determined empirically).

[0077] It should be understood that the above description is intended only as an example, and many other embodiments are possible within the scope of the invention as defined in the appended claims.

[0078] This public disclosure also includes the following configurations: 1. An optical system for guiding image illumination incident at an insertion region to an eye-tracking box for viewing by a user's eye, the optical system comprising a light-guiding optical element (LOE) formed of a transparent material, the LOE comprising: (a) a first region comprising a first set of mutually parallel planar partially reflective surfaces having a first orientation; (b) a second region comprising a second set of mutually parallel planar partially reflective surfaces having a second orientation not parallel to the first orientation; and (c) a set of mutually parallel main outer surfaces extending across the first region and the second region such that both the first set of partially reflective surfaces and the second set of partially reflective surfaces are located between the main outer surfaces, wherein the second set of partially reflective surfaces is angled to the main outer surfaces such that a portion of image illumination propagating from the first region to the second region within the LOE via internal reflection at the main outer surfaces is coupled out of the LOE toward the eye-tracking box, and wherein the first set of partially reflective surfaces is oriented such that a portion of image illumination propagating within the LOE via internal reflection at the main outer surfaces from the insertion region is deflected toward the second region. The first set of partially reflective surfaces includes: a first partially reflective surface located near the coupling region to contribute to a first portion of the field of view seen by the user at the eye-tracking box; a third partially reflective surface located distal to the coupling region to contribute to a third portion of the field of view seen by the user at the eye-tracking box; and a second partially reflective surface located in an intermediate plane between the first partially reflective surface and the third partially reflective surface to contribute to a second portion of the field of view seen by the user at the eye-tracking box. The second portion of the reflective surface is deployed in a sub-region of the intermediate plane such that the image propagating from the coupling region to the third portion of the reflective surface and contributing to the third portion of the field of view seen by the user at the eye tracker passes through the intermediate plane without passing through the second portion of the reflective surface. 2. The optical system of claim 1, wherein the coupling region includes a coupling prism having a first planar surface that is a continuation of one of the main outer surfaces in the first region, and the coupling prism having a thickness dimension greater than the thickness of the LOE, measured perpendicular to the main outer surface. 3. The optical system of claim 2, wherein the coupling prism presents a transition line between the coupling surface and the coupling prism as the LOE, the coupling surface defining the optical aperture of the coupling prism in a dimension parallel to the main outer surface, and the transition line defining the optical aperture of the coupling prism in a dimension perpendicular to the main outer surface. 4. The optical system of claim 2, wherein the first set of partially reflective surfaces further includes at least one partially reflective surface located within the volume of the coupling prism. 5. An optical system for guiding image illumination incident at an insertion region to an eye-tracking box for viewing by a user's eye, the optical system comprising a light-guiding optical element (LOE) formed of a transparent material, the LOE comprising: (a) a first region comprising a first set of mutually parallel planar partially reflective surfaces having a first orientation; (b) a second region comprising a second set of mutually parallel planar partially reflective surfaces having a second orientation not parallel to the first orientation; and (c) a set of mutually parallel main outer surfaces extending across the first region and the second region such that both the first set of partially reflective surfaces and the second set of partially reflective surfaces are located between the main outer surfaces, wherein the second set of partially reflective surfaces is angled to the main outer surfaces such that a portion of image illumination propagating from the first region to the second region within the LOE via internal reflection at the main outer surfaces is coupled out of the LOE toward the eye-tracking box, and wherein the first set of partially reflective surfaces is oriented such that a portion of image illumination propagating within the LOE via internal reflection at the main outer surfaces from the insertion region is deflected toward the second region. The coupling region includes a coupling prism, the coupling prism having a first planar surface that is a continuation of one of the main outer surfaces in the first region, and the coupling prism having a thickness dimension, measured perpendicular to the main outer surface, greater than the thickness of the LOE. Furthermore, the coupling prism presents a transition line between the coupling surface and the coupling prism as the LOE, the coupling surface defines the optical aperture of the coupling prism in a dimension parallel to the main outer surface, and the transition line defines the optical aperture of the coupling prism in a dimension perpendicular to the main outer surface. 6. The optical system of claim 5, wherein the first set of partial reflective surfaces further includes at least one partial reflective surface located within the volume of the coupled prism. 7. An optical system for guiding image illumination incident at an insertion region to an eye-tracking box for viewing by a user's eye, the optical system comprising a light-guiding optical element (LOE) formed of a transparent material, the LOE comprising: (a) a first region comprising a first set of mutually parallel planar partially reflective surfaces having a first orientation; (b) a second region comprising a second set of mutually parallel planar partially reflective surfaces having a second orientation not parallel to the first orientation; and (c) a set of mutually parallel main outer surfaces extending across the first region and the second region such that both the first set of partially reflective surfaces and the second set of partially reflective surfaces are located between the main outer surfaces, wherein the second set of partially reflective surfaces is angled to the main outer surfaces such that a portion of image illumination propagating from the first region to the second region within the LOE via internal reflection at the main outer surfaces is coupled out of the LOE toward the eye-tracking box, and wherein the first set of partially reflective surfaces is oriented such that a portion of image illumination propagating within the LOE via internal reflection at the main outer surfaces from the insertion region is deflected toward the second region. The coupling region includes a coupling prism, the coupling prism having a first planar surface that is a continuation of one of the main outer surfaces in the first region, and the coupling prism having a thickness dimension, measured perpendicular to the main outer surface, greater than the thickness of the LOE. Furthermore, the first set of partial reflective surfaces also includes at least one partial reflective surface located within the volume of the coupled prism. 8. The optical system of claim 7, wherein the coupling prism presents a transition line between the coupling surface and the coupling prism as the LOE, the coupling surface defining the optical aperture of the coupling prism in a dimension parallel to the main outer surface, and the transition line defining the optical aperture of the coupling prism in a dimension perpendicular to the main outer surface. 9. The optical system of any one of claims 2 to 8, wherein the coupling prism is bonded to the LOE at an edge surface of the LOE. 10. The optical system of any one of claims 2 to 8, wherein the coupling prism is bonded to one of the main outer surfaces of the LOE.

[0079] 12: Optical Frame (LOE) 15: Coupled Region 16: First Area 17: First group of partially reflective surfaces 17A: First part of the reflective surface 17B: Second part of the reflective surface 17C: Third part of the reflective surface 18: Second Zone 19: Second group of partially reflective surfaces 200: Image Projector 202: Coupled Prism 202L: Coupled Prism 202M: Coupled Prism 202P: Coupled Prism 202Q: Coupled Prism 202R: Coupled Prism 202T: Small Plane Section 202T2: Small Plane Section 202Y: Prism 203L: Aperture 203L2: Aperture 203V: Aperture 204, 370: Waveguide 206: Reflector 206A, 206B, 206V, 224, 226, 336, 338, 390: small facet 206L: First group of partially reflective surfaces 208: Eye Center 210: Area 22: Intermediate Plane 220A: Image Rays 220A1, 220A2, 220B1, 220B2, 220C: Images 220B: Guiding Direction 221: Angle 228: Circle 23: Arrow 24: Main outer surface 240: Coupled Region 244A, 244B, 244C: Curves 250, 252, 260, 262: Beams 26: Eye-tracking box 264: Prismatic Mirror 270: Laser 272: Scanning mirror 274: Diffuser 276, 292: Polarizing Beam Splitter (PBS) 278: Collimating Mirror 279:Lower face 28: Coupling Region 280: Refractive lens 282: Prism section 283: Prism 284: Mirror 286: Interface 290: Prism 294: Reflective Collimating Lens 296: Refractive Lens 298: Flat reflector 300: Region Designation 300F: Front 300S: Board 302: Prism 302F: Pattern 302S: Pattern 304A: Board 304B: Board 304C: Board 306: Vertical entrance 308: Optical Devices 310: Mirror / Mirror surface 312: Lower waveguide plane 334A1, 334A2, 334B1, 334B2: Images 340: Shaded area 342: Area 372: Coupled Region 374: Partial reflector 376: Optical Devices 378: Coupled Prism 394, 396: Masks 398: Transparent Coating SD: Region SL: Region SV: Region

Claims

1. A method for generating a light guide, the method comprising the steps of: (a) providing: (i) a transparent prism of a transparent material, the transparent prism having no internal reflective surface, the transparent prism having a first plane and a second plane not parallel to the first plane; (ii) A first planar plate of transparent material, the first planar plate comprising a first set of partially reflective inner surfaces that are parallel to each other, the first planar plate having a first planar attachment surface; (iii) a second planar plate of transparent material, the second planar plate comprising a second set of partially reflective inner surfaces parallel to each other, the second planar plate having a second planar attachment surface; (b) joining the first planar attachment surface of the first planar plate to the first plane of the transparent prism, and joining the second planar attachment surface of the second planar plate to the second plane of the transparent prism to form a rigid optical element, wherein the first set of partially reflective inner surfaces is parallel to the second set of partially reflective inner surfaces, and a straight line between at least one of the first set of partially reflective inner surfaces and at least one of the second set of partially reflective inner surfaces passes through the transparent prism; (c) The rigid optical element is sliced ​​along a plurality of parallel slicing planes passing through the transparent prism and the first and second planar plates to form a plurality of light guides.

2. The method as described in request item 1, wherein, The providing step further includes: providing a third small planar plate of transparent material, the third small planar plate comprising a third set of partially reflective inner surfaces parallel to each other, the third small planar plate having a third planar attachment surface, and wherein the joining step further includes: joining the third planar attachment surface of the third small planar plate to a third plane of the transparent prism, such that the third small planar plate forms part of the rigid optical element, in which the third set of partially reflective inner surfaces is parallel to the first set of partially reflective inner surfaces and the second set of partially reflective inner surfaces, and the third plane of the transparent prism is not parallel to the first plane and the second plane.

3. The method as described in claim 2, wherein, In the rigid optical element, the first and second planar plates abut against the third planar plate.

4. The method as described in claim 2, wherein, In the rigid optical element, the first planar plate, the second planar plate, and the third planar plate form a continuous body around a portion of the transparent prism.

5. The method as described in claim 1, further comprising: Prior to slicing, the rigid optical element is attached to the attachment surface of a stack of bonding plates having a partially reflective interface, the interface and the attachment surface being deployed such that after slicing, each of the plurality of light guides includes a light guide portion having a set of coupled partial reflectors oriented at an angle to the slice plane.

6. An optical guide, comprising: (a) A transparent prism made of a transparent material, said transparent prism having no internal reflective surface; (b) A first planar plate of transparent material, the first planar plate comprising a first set of partially reflective inner surfaces parallel to each other, the first planar plate being joined to the transparent prism at a first planar interface; (c) a second planar plate of transparent material, the second planar plate comprising a second set of partially reflective inner surfaces parallel to each other, the second planar plate being joined to the transparent prism at a second planar interface not parallel to the first planar interface, wherein the transparent prism, the first planar plate and the second planar plate together form at least a portion of a rigid optical element defined by a pair of parallel surfaces for supporting internal reflection within the rigid optical element, and wherein the first set of partially reflective inner surfaces is parallel to the second set of partially reflective inner surfaces, and wherein a straight line between at least one of the first set of partially reflective inner surfaces and at least one of the second set of partially reflective inner surfaces passes through the transparent prism.

7. The optical guide as described in claim 6, further comprising: A third planar plate of transparent material, the third planar plate comprising a third set of partially reflective inner surfaces parallel to each other, the third planar plate being joined to the transparent prism at a third planar interface, the third planar plate forming part of the rigid optical element, wherein the third set of partially reflective inner surfaces is parallel to the first set of partially reflective inner surfaces and the second set of partially reflective inner surfaces, and the third planar interface is not parallel to the first planar interface and the second planar interface.

8. The optical guide as described in claim 7, wherein, The first small planar plate and the second small planar plate abut against the third small planar plate.

9. The optical guide as described in claim 7, wherein, The first, second, and third planar plates form a continuous body around a portion of the transparent prism.

10. The optical guide as described in claim 6, wherein, The rigid optical element further includes a coupling light guide portion, which includes a coupling portion reflector oriented at an angle to the pair of parallel surfaces.

Images