Optical system comprising a light guiding optical element with two-dimensional expansion

Abstract

The present disclosure relates to optical systems comprising light-guide optical elements with two-dimensional expansion. An optical system comprising a light-guide optical element (LOE) having a first set of mutually parallel partially reflecting surfaces and a second set of mutually parallel partially reflecting surfaces oriented differently from the first set. Both sets of partially reflecting surfaces are located between a set of mutually parallel major outer surfaces. Image illumination introduced at a coupling-in location propagates along the LOE, is redirected by the first set of partially reflecting surfaces towards the second set of partially reflecting surfaces, where the image illumination is coupled out towards a user's eye. The first set of partially reflecting surfaces is implemented as partial surfaces located at positions required for filling an eyebox with a desired image. Additionally or alternatively, the spacing of the first set of partially reflecting surfaces varies across a first region of the LOE. Additional features relate to the relative orientation of the projector and the partially reflecting surfaces to improve compactness and enable various adjustments.

Description

[0001] This application is a divisional application of the invention patent application filed on September 9, 2019, with application number "201980057892.X" and invention title "Optical System Including a Two-Dimensional Extended Optical Guide Element". Technical Field

[0002] The present invention relates to optical systems, and more particularly to optical systems comprising optical guide optical elements (LOEs) for achieving optical aperture expansion. Background Technology

[0003] Many near-eye display systems include a transparent light-guide optics (LOE) or "waveguide" placed in front of the user's eye. The LOE or waveguide transmits an image within itself via internal reflection and then couples the image out toward the user's eye via a suitable output coupling mechanism. The output coupling mechanism can be based on an embedded partial reflector or "facet," or it can employ a diffraction mode. The following description will primarily relate to facet-based coupling devices; however, it should be understood that various features of the invention also apply to diffraction devices. Summary of the Invention

[0004] This invention is an optical system.

[0005] According to the teachings of embodiments of the present invention, an optical system is provided for guiding an image illumination injected 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 includes: (a) a first region comprising a first set of flat, mutually parallel partially reflective surfaces having a first orientation; (b) a second region comprising a second set of flat, mutually parallel 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 both the first and second sets of partially reflective surfaces are located between the main outer surfaces, wherein the second set of partially reflective surfaces and... The main outer surface is angled 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 a first set of partially reflective surfaces is oriented such that a portion of the image illumination propagating from the coupled region within the LOE via internal reflection at the main outer surface is deflected toward the second region, wherein each of the partially reflective surfaces in the first set includes a partially reflective coating at an interface plane between two plates forming part of the LOE, and wherein the partially reflective coating is located on a first portion of the interface plane, and at least one of the partially reflective surfaces has a second portion of the interface plane that is joined to form an optical continuum between the two plates.

[0006] According to another feature of an embodiment of the invention, the envelope of a light path that propagates within the LOE from the coupling region, is deflected by a partial reflective surface of the first set of partial reflective surfaces, and is coupled out by a partial reflective surface of the second set of partial reflective surfaces in the direction of reaching the eye-tracking box defines the imaging region of a partial reflective surface of the first set of partial reflective surfaces, and wherein a region of the partial reflective surface of the first set of partial reflective surfaces located outside the envelope defines a non-imaging region of the partial reflective surface of the first set of partial reflective surfaces, wherein a majority of the non-imaging region is combined to form an optical continuum between the two plates.

[0007] According to another feature of an embodiment of the invention, the first set of partial reflective surfaces has a non-uniform spacing, such that the spacing between adjacent partial reflective surfaces closer to the coupling region is smaller than the spacing between adjacent partial reflective surfaces farther from the coupling region.

[0008] According to another feature of an embodiment of the invention, the optical system further includes an image projector for projecting a collimated image having an angular field of view around the optical axis. The image projector is optically coupled to the LOE to introduce the collimated image into the LOE at the coupling region as a propagating image propagating within the LOE via internal reflection at the primary outer surface. The propagating image is partially reflected by a first set of partially reflective surfaces to generate a deflected propagating image propagating within the LOE via internal reflection at the primary outer surface. The deflected propagating image is partially reflected by a second set of partially reflective surfaces to generate an outgoing image pointing outward from one of the primary outer surfaces toward the eye-tracking box. The optical axis of the outgoing image is tilted relative to the normal of the primary outer surface and has a non-zero tilt component along the in-plane extension direction of the second set of partially reflective surfaces.

[0009] According to another feature of an embodiment of the invention, an image is configured to project onto an eye-tracking box using a main axis, the main axis including an X-axis corresponding to a first horizontal or vertical axis of the projected image and a Y-axis corresponding to another axis of the projected image, wherein a second set of partially reflective surfaces has an extension direction parallel to the main outer surface, the extension direction having an angular offset relative to the X-axis.

[0010] According to another feature of an embodiment of the invention, an image is configured to project onto an eye-tracking box using a main axis, the main axis including an X-axis corresponding to a first horizontal or vertical axis of the projected image and a Y-axis corresponding to another axis of the projected image. The optical system further includes an image projector for projecting a collimated image having an angular field of view around the optical axis. The image projector is optically coupled to the LOE to introduce the collimated image into the LOE at a coupling region as a propagated image that propagates within the LOE via internal reflection at the main outer surface. The in-plane component of the optical axis of the propagated image is tilted relative to the X-axis toward the boundary of the second region.

[0011] According to another feature of an embodiment of the invention, the in-plane component of one end of the field of view of the propagating image is substantially parallel to the X-axis.

[0012] According to another feature of an embodiment of the invention, an image is configured to project onto an eye-tracking box using a main axis, the main axis including an X-axis corresponding to a first horizontal or vertical axis of the projected image and a Y-axis corresponding to another axis of the projected image. The optical system further includes an image projector for projecting a collimated image having an angular field of view around the optical axis. The image projector is optically coupled to the LOE to introduce the collimated image into the LOE at a coupling region as a propagated image propagating within the LOE via internal reflection at the main outer surface. The propagated image is partially reflected by a first set of partially reflective surfaces to generate a deflected propagated image propagating within the LOE via internal reflection at the main outer surface. The in-plane component of the optical axis of the deflected propagated image is tilted relative to the Y-axis.

[0013] According to the teachings of embodiments of the present invention, an optical system is also provided for projecting an image injected at a coupling region for viewing by a user's eye at an eye-tracking box. The image is viewed using a principal axis, which includes an X-axis corresponding to a horizontal or vertical axis of the projected image and a Y-axis corresponding to an axis perpendicular to the X-axis of the projected image. The optical system includes a light-guiding optical element (LOE) formed of a transparent material. The LOE includes: (a) a first region comprising a first set of flat, mutually parallel partially reflective surfaces having a first orientation; (b) a second region comprising a second set of flat, mutually parallel partially reflective surfaces having a second orientation not parallel to the first orientation; and (c) a set of mutually parallel principal axes. The outer surface, the main outer surface, extends across the first region and the second region, such that both the first set of partial reflective surfaces and the second set of partial reflective surfaces are located between the main outer surface, wherein the second set of partial reflective surfaces is at an angle 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 partial reflective surfaces is oriented such that a portion of the image illumination propagating from the coupled region within the LOE via internal reflection at the main outer surface is deflected toward the second region, and wherein the second set of partial reflective surfaces has an extension direction parallel to the main outer surface, the extension direction having an angular offset relative to the X-axis.

[0014] According to the teachings of embodiments of the present invention, an optical system is also provided for projecting an image injected at a coupling region for viewing by a user's eye at an eye-tracking box. The image is viewed using a principal axis, the principal axis including an X-axis corresponding to a horizontal or vertical axis of the projected image, and a Y-axis corresponding to an axis perpendicular to the X-axis of the projected image. The optical system includes a light-guide optical element (LOE) formed of a transparent material, the LOE comprising: (a) a first region including a first set of flat, mutually parallel partially reflective surfaces having a first orientation; (b) a second region including a second set of flat, mutually parallel 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 set of partially reflective surfaces and the second set of partially reflective surfaces... The surfaces are all located between the main outer surface, wherein the second set of partially reflective surfaces is at an angle 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 from the coupling region within the LOE via internal reflection at the main outer surface is deflected toward the second region. The optical system also includes an image projector for projecting a collimated image having an angular field of view around the optical axis. The image projector is optically coupled to the LOE to introduce the collimated image into the LOE at the coupling region as a propagated image propagating within the LOE via internal reflection at the main outer surface, wherein the in-plane component of the optical axis of the propagated image is inclined relative to the X-axis toward the boundary of the second region.

[0015] According to another feature of an embodiment of the invention, the in-plane component of one end of the field of view of the propagating image is substantially parallel to the X-axis.

[0016] According to the teachings of embodiments of the present invention, an optical system is also provided for projecting an image injected at a coupling region for viewing by a user's eye at an eye-tracking box. The image is viewed using a principal axis, the principal axis including an X-axis corresponding to a horizontal or vertical axis of the projected image, and a Y-axis corresponding to an axis perpendicular to the X-axis of the projected image. The optical system includes a light-guide optical element (LOE) formed of a transparent material, the LOE including: (a) a first region comprising a first set of flat, mutually parallel partially reflective surfaces having a first orientation; (b) a second region comprising a second set of flat, mutually parallel 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 both the first and second sets of partially reflective surfaces are located between the main outer surfaces, wherein the second set of partially reflective surfaces... The surface 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 from the coupling region within the LOE via internal reflection at the main outer surface is deflected toward the second region. The optical system also includes an image projector for projecting a collimated image having an angular field of view around the optical axis. The image projector is optically coupled to the LOE to introduce the collimated image into the LOE at the coupling region as a propagated image propagating within the LOE via internal reflection at the main outer surface. The propagated image is partially reflected by the first set of partially reflective surfaces to generate a deflected propagated image propagating within the LOE via internal reflection at the main outer surface, wherein the in-plane component of the optical axis of the deflected propagated image is tilted relative to the Y-axis.

[0017] According to another feature of an embodiment of the invention, the eye-tracking box is defined by at least one straight line parallel to the X-axis.

[0018] Another feature of an embodiment of the invention is that the projected image is a rectangular image with edges parallel to the X and Y axes.

[0019] According to another feature of an embodiment of the invention, a support device is also provided, which is configured to support the LOE relative to the user's head, wherein one of the main outer surfaces faces the user's eyes and is oriented horizontally relative to the user's eyes along an orientation such that the X-axis is horizontally oriented.

[0020] According to another feature of an embodiment of the invention, the first region and the second region are separated by a boundary extending parallel to the X-axis.

[0021] According to the teachings of embodiments of the present invention, an optical system is also provided for guiding an image illumination injected 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 includes: (a) a first region comprising a first set of flat, mutually parallel partially reflective surfaces having a first orientation; (b) a second region comprising a second set of flat, mutually parallel 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 set of partially reflective surfaces and the second set of partially reflective surfaces... The partial reflective surfaces are all located between the main outer surfaces, wherein the second set of partial reflective surfaces is at an angle 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 from the LOE toward the eye-tracking box, and wherein the first set of partial reflective surfaces is oriented such that a portion of the image illumination propagating from the coupling region within the LOE via internal reflection at the main outer surfaces is deflected toward the second region, and wherein the first set of partial reflective surfaces has a non-uniform spacing such that the spacing between adjacent partial reflective surfaces closer to the coupling region is smaller than the spacing between adjacent partial reflective surfaces farther from the coupling region.

[0022] According to the teachings of embodiments of the present invention, an optical system is also provided for guiding image illumination injected 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 includes: (a) a first region comprising a first set of flat, mutually parallel partially reflective surfaces having a first orientation; (b) a second region comprising a second set of flat, mutually parallel 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 both 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 from the LOE toward the eye-tracking box. The optical system further includes an image projector for projecting a collimated image having an angular field of view around the optical axis. The image projector is optically coupled to the LOE to introduce the collimated image into the LOE at the coupling region as a propagated image propagating within the LOE through internal reflection at the main outer surface. The propagated image is partially reflected by the first set of partial reflective surfaces to generate a deflected propagated image propagating within the LOE through internal reflection at the main outer surface. The deflected propagated image is partially reflected by the second set of partial reflective surfaces to generate an outgoing image pointing outward from one of the main outer surfaces toward the eye-tracking box. The optical axis of the outgoing image is tilted relative to the normal of the main outer surface and has a non-zero tilt component along the in-plane extension direction of the second set of partial reflective surfaces. Attached Figure Description

[0023] This invention has been described by way of example only with reference to the accompanying drawings, in which:

[0024] Figure 1A and Figure 1B The diagram is a schematic isometric view of an optical system implemented using a light-guiding optical element (LOE) constructed and operated according to the teachings of the present invention, showing a top-down configuration and a side-injection configuration, respectively.

[0025] Figure 2A and Figure 2B It comes from Figure 1A or Figure 1B A magnified schematic isometric view of the LOE, showing the ray paths of the two end fields of the image;

[0026] Figure 2C yes Figure 1A and Figure 1BAn overview of the combination of the field and the additional field of the overall envelope of the partial reflective surface required to form a complete image at the eye-tracking box;

[0027] Figure 2D yes Figure 2C An alternative implementation method, in which a portion of the reflective surface is selectively implemented;

[0028] Figure 2E It is similar to Figure 2D The view shows the variable spacing between the partially reflective surfaces;

[0029] Figure 2F It is similar to Figure 2E The view shows the area that can be removed in the LOE;

[0030] Figure 3A and Figure 3B It is similar to Figure 2E The view shows the potential ray paths that form ghosting with and without the partial reflective surface, outside the desired contour of the partially reflective surface;

[0031] Figure 4A It is based on Figure 1A or Figure 1B An enlarged schematic isometric view of the first region of another implementation of LOE, showing the ray paths of the two end fields;

[0032] Figure 4B It is similar to Figure 4A The view shows a partial representation of partially reflective surfaces with variable spacing between them;

[0033] Figure 4C It is similar to Figure 4B The view shows the various parts of the reflective surface required at the end of the field;

[0034] Figure 5A This includes, according to the above, regarding Figure 2E The principle shown is implemented with Figure 4C A magnified schematic isometric view of the first region, similar to the first region's LOE;

[0035] Figure 5B It is similar to Figure 5A The view shows the area of ​​the LOE that can be excised;

[0036] Figures 6A to 6D It is similar to Figures 2A to 2F A schematic isometric view illustrating the effects of various angular offset parameters; and

[0037] Figure 7This is a schematic top view of a near-eye display, illustrating the facial curves and angular offset required for convergence correction according to aspects of the invention. Detailed Implementation

[0038] Some embodiments of the present invention provide an optical system including a light-guiding optical element (LOE) for achieving optical aperture expansion for use in a head-up display, and most preferably a near-eye display that may be a virtual reality display or more preferably an augmented reality display.

[0039] exist Figure 1A and Figure 1B The diagram schematically illustrates an exemplary implementation of a near-eye display (generally designated 10) in the form of a LOE 12 employing the teachings of an embodiment of the invention. The near-eye display 10 employs a compact image projector (or "POD") 14 optically coupled to inject an image into the LOE (interchangeably referred to as a "waveguide," "substrate," or "plate") 12, in which image light is captured in one dimension by internal reflection at a set of mutually parallel, flat outer surfaces. Light is directed toward a set of partially reflective surfaces (interchangeably referred to as "facets") parallel to each other and obliquely inclined relative to the direction of image light propagation, wherein each successive facet deflects a portion of the image light in a deflection direction, which is also captured / guided within the substrate by reflection. The first set of facets is not in... Figure 1A and Figure 1B It is shown separately, but located in the first region of the LOE (designated as 16). This partial reflection at the successive facets achieves an expansion of the optical aperture in the first dimension.

[0040] In a first set of preferred but non-limiting examples of the invention, the aforementioned set of facets is orthogonal to the main outer surface of the substrate. In this case, the injected image and its conjugate, which undergoes internal reflection as it propagates within region 16, are both deflected and become conjugate images propagating in the deflection direction. In an alternative set of preferred but non-limiting examples, the first set of partially reflective surfaces is angled relative to the main outer surface of the LOE. In the latter case, the injected image or its conjugate forms the desired deflected image propagating within the LOE, while another reflection can be minimized, for example, by employing an angle-selective coating on the facets, wherein the angle-selective coating makes the facets relatively transparent to the range of incident angles from which images that do not require their reflection are presented.

[0041] The first set of partially reflective surfaces deflects the image illumination from a first direction of propagation captured within the substrate by total internal reflection (TIR) ​​to a second direction of propagation also captured within the substrate by TIR.

[0042] The deflected image is then directed into a second substrate region 18, which can be implemented as adjacent different substrates or as a continuation of a single substrate. In the second substrate region 18, coupling devices (another set of partially reflective facets or diffractive optical elements) gradually couple a portion of the image towards the observer's eye located within the area defined as the eye-tracking box (EMB), thereby achieving a second-dimensional optical aperture expansion. The overall device can be implemented individually for each eye and is preferably supported relative to the user's head, with each LOE 12 facing the corresponding eye. In a particularly preferred option as shown here, the support device is implemented as an eyeglass frame with sides 20 for supporting the device relative to the user's ears. Other forms of support devices can also be used, including but not limited to headbands, face shields, or devices suspended from a helmet.

[0043] This document refers to the X-axis and Y-axis in the accompanying drawings and claims, wherein the X-axis is horizontal along the general extension direction of the first region of the LOE. Figure 1A ) or vertical ( Figure 1B ) extends, and the Y-axis extends perpendicular to the X-axis, that is, in Figure 1A Extending vertically in the middle and Figure 1B Mid-level extension.

[0044] In very rough terms, one can consider that the first region 16 of the first LOE or LOE 12 achieves aperture expansion in the X direction, while the second region 18 of the second LOE or LOE 12 achieves aperture expansion in the Y direction. The details of the angular expansion of the different parts of the field of view will be described more precisely below. It should be noted that, as Figure 1A The orientation shown can be viewed as a "top-down" implementation, in which image illumination entering the main (second region) of the LOE enters from the top edge, while... Figure 1B The orientation shown can be considered a "lateral injection" implementation, in which the axis, referred to here as the Y-axis, is deployed horizontally. In the remaining figures, various features of certain embodiments of the invention will be shown in the context of a "top-down" orientation, similar to... Figure 1A However, it should be understood that all these features also apply to lateral injection implementations that fall within the scope of this invention. In some cases, other intermediate orientations are also applicable, and unless explicitly excluded, such other intermediate orientations are included within the scope of this invention.

[0045] The POD used with the apparatus of the present invention is preferably configured to generate a collimated image, i.e., in which the light for each image pixel is a parallel beam collimated to infinity, wherein the angular direction corresponds to the pixel position. Therefore, the image illumination spans an angular range corresponding to the angular field of view in two dimensions.

[0046] Image projector 14 includes at least one light source typically deployed to illuminate a spatial light modulator, such as an LCOS chip. The spatial light modulator modulates the projected intensity of each pixel of the image, thereby generating the image. Alternatively, the image projector may include a scanning device typically implemented using a fast scanning mirror that scans across the image plane of the projector from the illumination of the laser light source, while the intensity of the beam is changed synchronously with the pixel-by-pixel movement, thereby projecting the desired intensity for each pixel. In both cases, collimating optics are arranged to generate an output projected image collimated to infinity. Some or all of the above components are typically arranged on the surface of one or more polarization beam splitter (PBS) cubes or other prism devices known in the art.

[0047] Optical coupling between the image projector 14 and the LOE 12 can be achieved by any suitable optical coupling, for example, via a coupling prism having an angled input surface, or via a reflective coupling device, via a side edge and / or one of the main outer surfaces of the LOE. Details of the coupling configuration are not important to the present invention and are shown herein as a non-limiting example of a wedge prism 15 applied to one of the main outer surfaces of the LOE.

[0048] It should be understood that the near-eye display 10 includes various additional components, typically including a controller 22 for actuating the image projector 14, which is typically powered by a small onboard battery (not shown) or some other suitable power source. It should be understood that the controller 22 includes all the necessary electronic components for driving the image projector, such as at least one processor or processing circuitry, all of which are known in the art.

[0049] Now go to Figures 2A to 2FThe optical characteristics of the near-eye display implementation are shown in more detail. Specifically, a more detailed view of a light-guided optical element (LOE) 12 formed of a transparent material is shown. The LOE 12 includes a first region 16 and a second region 18. The first region 16 includes a first set of flat, mutually parallel partially reflective surfaces 17 having a first orientation, and the second region 18 includes a second set of flat, mutually parallel partially reflective surfaces 19 having a second orientation that is not parallel to the first orientation. A set of mutually parallel main outer surfaces 24 extends across the first region 16 and the second region 18, such that both the first set of partially reflective surfaces 17 and the second set of partially reflective surfaces 19 are located between the main outer surfaces 24. Most preferably, the set of main outer surfaces 24 is a pair of surfaces that are each continuous across the entire first region 16 and the second region 18; however, the choice of increasing or decreasing thickness between regions 16 and 18 also falls within the scope of the invention. Regions 16 and 18 can be placed close together such that they contact each other at the boundary, which can be a straight boundary or some other form of boundary. Alternatively, depending on the specific application, one or more additional LOE regions may be present between regions 16 and 18 to provide various additional optical or mechanical functions. Although the invention is not limited to any particular manufacturing technique, in some particularly preferred implementations, a particularly high-quality main outer surface is achieved by employing continuous outer plates with separately formed regions 16 and 18 sandwiched between the continuous outer plates to form a composite LOE structure.

[0050] The optical properties of the LOE can be understood by tracing the image illumination path in reverse. The second set of partially reflective surfaces 19 are angled to the main outer surface 24, such that a portion of the image illumination propagating from the first region 16 to the second region 18 within the LOE 12 via internal reflection at the main outer surface is coupled out of the LOE toward the eye-tracking box 26. The first set of partially reflective surfaces 17 is oriented such that a portion of the image illumination propagating within the LOE 12 via internal reflection at the main outer surface from the coupling region (coupling prism 15) is deflected toward the second region 18.

[0051] exist Figure 2A The angular spread of the projected image from image projector 14 in one dimension is represented by an illumination cone extending from the POD aperture on the right side of the LOE toward the left side of the LOE. In the non-limiting example shown here, the central optical axis of the POD defines a propagation direction aligned with the X-axis within the LOE, and the angular spread (within the LOE) is approximately ±16°. (It should be noted that the angular FOV increases in air due to variations in refractive index). A first set of partially reflective surfaces 17 is shown in the first region 16, and a second set of partially reflective surfaces 19 is shown in the second region 18.

[0052] The near-eye display is designed to provide the user's eye with the full field of view of the projected image, with the user's eye positioned within a permissible range of positions specified by the "eye-tracking box" (EMB) 26 (i.e., typically represented as a rectangle, spaced apart from the plane of the LOE from which the pupil will view the projected image). To reach the eye-tracking box, light must be coupled from the second region 18 toward the EMB 26 via a second set of partially reflective surfaces 19. To provide the full field of view, each point in the EMB must receive the entire angular range of the image from the LOE. A larger rectangle 28 can be indicated by the field of view traced back from the EMB, with correlated illumination coupled from the LOE toward the EMB from rectangle 28.

[0053] Figure 2A The first end of the field of view is shown, corresponding to the lower left pixel of the projected image. A beam of light coupled into the LOE with a width corresponding to the optical aperture of the projector is shown propagating left and upward from the POD and partially reflected from a series of partially reflective surfaces 17. As shown here, only a subset of the facets generates reflections useful to the corresponding pixel in the image viewed by the user, and only sub-regions of these facets contribute to the viewing image of that pixel. The relevant regions are shown in thick black lines, and the rays reflected from facet 17 and then coupled out by facet 19 to the four corners of the EMB 26 corresponding to that pixel in the redirected image are shown. Here, and throughout the specification, it will be noted that only the in-plane propagation direction of the light during propagation within the LOE is shown, but the light actually follows a zigzag path of repeated inward reflections from the two main outer surfaces, and the entire dimension of the image field of view is encoded by the angle of the light relative to the main outer surfaces corresponding to the pixel position in the Y dimension. As an additional example, the deflected and coupled rays corresponding to the upper left end of the image as seen at the upper left corner of the EMB are shown in dashed lines.

[0054] Figure 2B It shows the relationship with Figure 2A The same configuration is used, but here the rays reaching the four corners of the EMB corresponding to the lower right pixel of the field of view are shown, with the relevant areas of the relevant reflective surface 17 also shown in thick lines.

[0055] Clearly, by further tracing the corresponding ray paths of all fields (directions or pixels) of the image reaching all regions of the EMB, the envelope of all ray paths propagating within the LOE from the coupling region, deflected by one of the first set of partial reflective surfaces, and coupled out by one of the second set of partial reflective surfaces along the direction reaching the eye-tracking box can be plotted, and this envelope defines the "imaging region" in each facet 17, while the remaining portion of the facet 17 outside the envelope is the "non-imaging region," where the "imaging region" is required to deflect the portion of the image illumination that contributes to the image reaching the EMB, and the "non-imaging region" does not contribute to the desired image. Figure 2C The simplified outline of the envelope corresponding to the “imaging area” of all facets 17 is shown in bold lines.

[0056] According to a particularly preferred implementation of the invention, the facet 17 is implemented as a "partial facet" such that partial reflectivity exists only within a sub-region of the cross-sectional region of region 16, which includes the "imaging region" of each facet plane, and preferably excludes at least a majority of some or all of the "non-imaging regions" in the facet. Figure 2D This implementation is schematically illustrated. The effective (partially reflective) area of ​​the facet preferably extends slightly beyond the minimum required for completing the geometry of EMB image projection to avoid anomalies that may be caused by defects at the coating edges, and in some cases the facet may also be extended further due to additional considerations related to the integer overlap between facets in the deflection image direction to achieve improved image uniformity. According to certain particularly preferred implementations, as shown, the distance of the farthest partially reflective facet encountered along the line from the coupling position gradually increases over most of the angular range of the image projected from the projector 14 as the angle away from the boundary of the second region 18 increases clockwise.

[0057] In cases where the first region 16 is formed by a stack of coated plates that are then cut at an appropriate angle (e.g., as described in PCT Patent Publication WO2007054928A1, and as is known in the art), the selective spatial deployment of the partially reflective surface can advantageously be achieved by forming a stack of plates, wherein the partially reflective coating is located on a first portion of the interface plane between two plates, while a second portion of the interface plane is joined (typically using a refractive index matching adhesive and without a coating) to form an optical continuum between the two plates. The selective application of the partially reflective coating is typically achieved by applying a suitable masking layer prior to the coating process and removing the masking layer at the end of the coating process.

[0058] According to alternative manufacturing techniques, stacks of full-area coated plates can be formed and then cut into the desired shape to include the volume of facets (e.g., corresponding to...). Figure 2D (The region shown has a small facet). Then, the desired form of the LOE is achieved by optically combining this irregular block containing the partially reflective facet with a complementary block of a simple refractive index-matching glass.

[0059] Figure 2E Similar to Figure 2DHowever, the following optical system is shown: in this optical system, the first set of partial reflective surfaces 17 have a non-uniform spacing between the planes of the surfaces, such that the spacing between adjacent partial reflective surfaces closer to the coupling region is smaller than the spacing between adjacent partial reflective surfaces farther from the coupling region. This variable spacing is preferred in many cases to enhance the uniformity of the projected image, as will be further explained below.

[0060] The optical axis is not actually parallel to the X-axis, but lies in the XZ plane, where the Z component entering the page is chosen such that the entire angular range of the depth dimension of the FOV undergoes total internal reflection at the surface of the main substrate. For simplicity, the graphical representation and description in this paper will only involve the in-plane (XY) components of the light propagation direction, which are referred to herein as "in-plane components" or "components parallel to the main outer surface of the LOE".

[0061] It should be noted that the direction of the uppermost ray in the field of view corresponds to the left side of the field of view reaching the observer's eye, while the direction of the lowest ray corresponds to the right side of the field of view. It should also be noted that some reflections from the left side of the field of view are reflected from a small plane near the right side of the LOE in a direction that will not reach the EMB, and are therefore lost. Similarly, some rays from the right side of the field of view are reflected from a small plane near the left side of the LOE and deflected in a direction that will not reach the EMB, and are therefore lost. Certain aspects of the invention utilize these observations to reduce the size of the first LOE (or LOE region) (and thus reduce volume and weight).

[0062] Specifically, Figure 2F The shadow was used to indicate Figure 2E The height of the first region 16 of the LOE 12 does not contribute to the image reaching the various regions of the EMB, and therefore these regions can be truncated without interfering with the image projection to the user's eye. It should also be noted that the optical aperture used to inject the image from the image projector is located in the lower half of the first region 16 of the LOE 12, because the portion of the image corresponding to the downward-angled light rays shown corresponds to the right side of the image field of view, which does not need to be reflected from the small plane closer to the left side of the first region 16. This allows for a relatively compact implementation of the first region 16 of the LOE 12. Specifically, the range of the LOE below the optical axis of the POD is chosen such that the light rays from the POD aperture corresponding to the rightmost pixel of the field of view reach the small plane that deflects the light rays toward the entire region of the EMB, but the small plane is shortened in areas where it can no longer reach the EMB at such angles. The reduction in the height of the first region 16 also results in a small reduction in the X-dimensionality, because the reduction in the LOE height brings the small plane closer to the EMB, and thus reduces the required X-dimensionality for covering the desired angular range of the FOV. Here and elsewhere in this document, it will be noted that the terms “resection” and “truncation” are used to refer to the final product relative to, for example, Figure 2AThe LOE is a theoretical starting point for the implementation of a reduced geometry or size, serving as a reference point. The term does not imply any implementation of physically cutting away material or any other particular manufacturing technique. It is not necessarily assumed that the LOE will be precisely truncated along the boundaries of the indicated areas, but rather that these areas provide design flexibility, allowing the LOE to be completed with any external profile deemed aesthetically preferred and / or mechanically compatible with additional details of the desired application.

[0063] It should be noted that, as mentioned above... Figures 2D to 2F The use of the facets can provide one or more of the following advantages, including improved efficiency and brightness, where the transmission of an image from a facet located far from the coupling region does not need to pass through so many additional facets before reaching the second LOE region. (See here for reference.) Figure 3A and Figure 3B This demonstrates another advantage.

[0064] Specifically, Figure 3A The region marked 17' is shown outside the envelope of the plane region required to transmit the projected image to the EMB. (This plane is typically one of many planes, but it is shown separately here for easier explanation.) Figure 3A The path of a downward-pointing image ray originating from the image projector is shown, passing directly through a partially reflective surface. This ray travels (through total internal reflection) into a second region 18, where it is incident on one of a second set of partially reflective surfaces 19 and, as shown, partially reflected, generating an undesirable "ghost" reflection that propagates upward back into the first region 16. The angle of this ray allows it to be reflected from a continuation of the facet 17' in a direction toward the EMB 24, in which case the ray can form a visible ghost that interferes with viewing the image.

[0065] Figure 3B The following diagram illustrates, in contrast, the occurrence of the same ghosting ray path when the facet is deployed only in or near the area required to form the output image within a reduced region. In this case, the light reflected from surface 19 and guided back to the first region 16 does not encounter any partially reflective surfaces as it propagates through the first region of the LOE. Therefore, the light continues its journey until it reaches the outer edge of the LOE, where it is preferably absorbed or diffused by a suitably positioned non-reflective surface.

[0066] exist Figures 2A to 2F In the example, the size of the first LOE region 16 above the optical axis of POD 14 cannot be significantly reduced because the leftmost region of the FOV must be reflected from the small plane at the leftmost end of the LOE. Figures 4A to 5BAn alternative method with additional features according to certain particularly preferred implementations of the invention is shown, which allows for a further reduction in the size of the first LOE region 16.

[0067] Specifically, in Figure 4A In the apparatus, the POD and / or coupling prism is rotated such that the central optical axis of the image projection forms a downward angle across the first LOE region 16, wherein, most preferably, this angle is chosen such that it is approximately parallel to the leftmost end of the projection FOV along the X-axis. In this case, the coupling of the POD is preferably at or near the upper end of the first LOE region 16 (typically at the upper third). The desired size of the LOD below the POD aperture is determined by a reference similar to [reference missing]. Figures 2A to 2F The aforementioned geometric considerations specify that all rays of the image should encounter a small plane that is properly positioned and angled to transmit the corresponding area of ​​the projected FOV to the entire EMB. In this case, the rightmost ray descends at a steeper angle, and the angle of the small plane is adjusted accordingly, but the overall Y-size of the first LOE is still further reduced.

[0068] In some cases, and such as Figure 4A The steeper angle shown on the right side of the mid-field of view particularly emphasizes the geometric requirement for "filling" the EMB, necessitating significantly different small-plane spacing between the right and left sides of the field of view. Therefore, in Figure 4A In the example shown, for the coupled optical aperture width as depicted, the left field is effectively filled by aligning one side of the pixel beam reflected from a small facet with the other side of the beam reflected from the adjacent facet. However, on the right side of the field, the uniform facet spacing, as shown, results in "black lines" (here shown as thick black lines) within which there is no image illumination. If the facet spacing decreases uniformly, this leads to the inverse problem of bright stripes near the left side of the field. To address this issue, a variable facet spacing is preferred, such as... Figure 4B The partial set of facets with corresponding geometry shown illustrates how to properly adjust the facet spacing to provide image illumination that “fills” the EMB for each end of the field of view. The facet spacing preferably varies gradually across the LOE region 16 (but not necessarily continuously or linearly).

[0069] As shown in the picture above Figures 2A to 2E The aforementioned method can identify the partial reflections provided by each small plane to fill the required area of ​​the EMB image for each field (pixel) of the image, such as for... Figure 4C The two end fields are shown in the diagram. Here, by defining an "envelope" encompassing all regions of all planes required to provide the output image at eye-tracking box 26, it is also possible to achieve a structure and function entirely similar to the reference above. Figure 2D and Figure 2EThe described method implements a first region 16 of LOE 12, which has selectively deployed partially reflective surfaces whose extent varies across the first region. Figure 5A The diagram shows the corresponding implementation of the overall optical system for this situation. Figure 5B The first and second LOEs are shown as additional regions that do not contribute to image projection and can be further excised as needed for each specific application, as illustrated in the figure.

[0070] Therefore, by deploying the image projector 14 and tilting the in-plane component of the optical axis of the propagating image relative to the X-axis toward the boundary of the second region 18, and most preferably ensuring that the in-plane component at one end of the field of view of the propagating image is substantially parallel to the X-axis, it is possible to achieve a result compared to Figures 2A to 2F The overall configuration is further compacted. In all other respects, it is used to achieve... Figures 4A to 5B The structure, function, and selection range of the device are as described above, referring to 2A to 2B. Figure 3B As stated above.

[0071] Apart from Figures 4A to 5B Besides the tilt of the optical axis of the image projector described, many other angular parameters can be used to achieve various adjustments to the characteristics of the optical system. Reference will now be made to... Figures 6A to 6D and Figure 7 Various examples are shown.

[0072] First refer to Figure 6A and Figure 6B These illustrate the geometry underlying the potential adjustment of the eye-tracking box position by the width dimension of the second region across LOE 12. Figure 6A In the middle, it is shown that is equivalent to Figures 2A to 2F The device, in which the light path corresponds to the central ray of the image viewed from the center of the eye-tracking box, results in the center localization of the EMB.

[0073] Figure 6BThe effect of implementing the second region 18 of LOE 12 is shown, wherein the facet 19 is angularly offset relative to the X-axis. In this case, the light rays forming the center of the field at the center of the eye-tracking box are shifted, resulting in a horizontally shifted eye-tracking box, which is useful in cases where an asymmetric deployment relative to the EMB of the LOE is required. In this context, the “extension direction” of the facet is considered to be the line of intersection between the facet and a plane parallel to the main outer surface of the LOE. An equivalent definition is the line of intersection between a plane containing a portion of the reflective surface and the main outer surface. This line is referred to herein as the extension direction of the facet parallel to the main outer surface, or the “in-plane” extension direction. In this context, the degree of “angular offset” relative to the X-axis depends on the desired degree of horizontal offset, but for some preferred cases, an offset in the range of 5 to 25 degrees is possible, although smaller and larger angular offsets are possible.

[0074] Go to Figure 6C and Figure 6D This illustrates another form of adjustment that allows for correction of "facial curvature" and / or convergence angle, such as... Figure 7 shown. Specifically, Figure 7 A schematic top view of a near-eye display is shown, in which the LOEs are deployed at an angle relative to each other, allowing the LOEs to be mounted within a "wrap-around" frame shaped to follow (to some extent) the side-to-side curvature of the face. To achieve stereoscopic vision in such a configuration, it is necessary to correct for the facial curvature so that the image follows parallel lines in space (…). Figure 7 The dotted line (in the diagram) is centered, and the parallel line is horizontally offset relative to the perpendicular line of the LOE. Alternatively or concurrently, in various applications, particularly but not exclusively for indoor use, it is desirable to provide a convergence angle between two displays so that an object viewed through the eyes of the displays appears to be in the user's desired direction. This correction also requires a deflection from the normal to the LOE plane with a component in the horizontal (X-axis) direction.

[0075] To achieve this correction, the image projector 14 and the first set of partial reflective surfaces 17 are oriented such that the propagating image coupled from the image projector 14 into the LOE is deflected by the facet 17 to generate a deflected propagating image that propagates with an in-plane component of the optical axis inclined relative to the Y-axis. After being coupled out by the facet 19, this offset results in the optical axis of the coupled image being deflected in the horizontal plane, i.e., inclined relative to the normal of the main outer surface, having a non-zero tilt component along the in-plane extension direction of the second set of partial reflective surfaces, such as... Figure 6D As shown.

[0076] Although these adjustments are presented as independent adjustments, it should be noted that various parameters such as the projector optical axis tilt, the plane angle of the first LOE region, and the plane angle of the second LOE region are interrelated. A change in one of these parameters will typically require corresponding adjustments to the others to ensure transmission across the entire field of view. Furthermore, these adjustments can cause the injected image to rotate around its central axis, which can be directly corrected by rotating the projector and / or coupling device. Figure 6D As shown schematically in the diagram.

[0077] As above Figure 1B As mentioned in the context, all the principles described above can also be applied to a "lateral" configuration, in which the image is injected from a POD located laterally outside the viewing area and vertically extended by a first set of facets, and then horizontally extended by a second set of facets for coupling into the user's eye. It should be understood that all the above configurations and variations also apply to lateral injection configurations.

[0078] Throughout the above description, reference has been made to the X-axis and Y-axis as shown in the figure, where the X-axis is horizontal or vertical and corresponds to the first dimension of optical aperture expansion, and the Y-axis is another principal axis corresponding to the second dimension of expansion. In this context, when the device is mounted on a user's head, its orientation relative to the device can be typically determined by a support device (e.g., the one described above). Figure 1A and Figure 1B The orientation defined by the eyeglass frame defines the X and Y axes. Other terms that are generally consistent with the definition of the X-axis include: (a) at least one straight line that demarcates the eye-tracking box, which may be used to define a direction parallel to the X-axis; (b) the edges of the rectangular projected image are generally parallel to the X and Y axes; and (c) the boundary between the first region 16 and the second region 18 generally extends parallel to the X-axis.

[0079] This invention also includes the following technical solutions:

[0080] 1. An optical system for guiding an image illumination injected at a coupling 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:

[0081] (a) A first region comprising a first set of flat, mutually parallel partially reflective surfaces having a first orientation;

[0082] (b) A second region comprising a second set of flat, mutually parallel partially reflective surfaces having a second orientation that is not parallel to the first orientation;

[0083] (c) A set of parallel main outer surfaces extending across the first region and the second region, such that both the first set of partial reflective surfaces and the second set of partial reflective surfaces are located between the main outer surfaces.

[0084] Wherein, the second set of partially reflective surfaces forms an oblique angle with 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 from the coupled region via internal reflection at the main outer surface is deflected toward the second region.

[0085] Each of the partially reflective surfaces in the first group of partially reflective surfaces includes a partially reflective coating at an interface plane between two plates forming part of the LOE, and wherein the partially reflective coating is located on a first portion of the interface plane, and at least one of the partially reflective surfaces has a second portion of the interface plane that is joined to form an optical continuum between the two plates.

[0086] 2. The optical system according to claim 1, wherein the envelope of a light path propagating within the LOE from the coupling region, deflected by a partial reflective surface of the first set of partial reflective surfaces, and coupled out by a partial reflective surface of the second set of partial reflective surfaces in the direction reaching the eye-tracking box defines the imaging region of the one partial reflective surface of the first set of partial reflective surfaces, and wherein a region of the one partial reflective surface of the first set of partial reflective surfaces located outside the envelope defines the non-imaging region of the one partial reflective surface of the first set of partial reflective surfaces, wherein a majority of the non-imaging region is combined to form an optical continuum between the two plates.

[0087] 3. The optical system according to Scheme 1, wherein the first set of partial reflective surfaces has a non-uniform spacing, such that the spacing between adjacent partial reflective surfaces near the coupling region is smaller than the spacing between adjacent partial reflective surfaces far from the coupling region.

[0088] 4. The optical system according to claim 1, wherein the optical system further includes an image projector for projecting a collimated image having an angular field of view around an optical axis, the image projector being optically coupled to the LOE to introduce the collimated image into the LOE at the coupling region as a propagating image propagating within the LOE via internal reflection at the primary outer surface, the propagating image being partially reflected by a first set of partially reflective surfaces to generate a deflected propagating image propagating within the LOE via internal reflection at the primary outer surface, the deflected propagating image being partially reflected by a second set of partially reflective surfaces to generate an outgoing image pointing outward from one of the primary outer surfaces toward the eye-tracking box, the optical axis of the outgoing image being tilted relative to the normal of the primary outer surface and having a non-zero tilt component along the in-plane extension direction of the second set of partially reflective surfaces.

[0089] 5. The optical system according to claim 1 is configured to project an image onto the eye-tracking box using a main axis, the main axis including an X-axis corresponding to a first horizontal or vertical axis of the projected image and a Y-axis corresponding to another axis of the projected image, wherein the second set of partial reflective surfaces has an extension direction parallel to the main outer surface, the extension direction having an angular offset relative to the X-axis.

[0090] 6. The optical system according to claim 1 is configured to project an image onto the eye-tracking box using a main axis, the main axis including an X-axis corresponding to a first horizontal or vertical axis of the projected image and a Y-axis corresponding to another axis of the projected image. The optical system further includes an image projector for projecting a collimated image having an angular field of view around the optical axis. The image projector is optically coupled to the LOE to introduce the collimated image into the LOE at the coupling region as a propagated image propagating within the LOE via internal reflection at the main outer surface, wherein the in-plane component of the optical axis of the propagated image is inclined relative to the X-axis toward the boundary of the second region.

[0091] 7. The optical system according to claim 6, wherein the in-plane component of one end of the field of view of the propagated image is substantially parallel to the X-axis.

[0092] 8. The optical system according to claim 1 is configured to project an image onto the eye-tracking box using a principal axis, wherein the principal axis includes an X-axis corresponding to a first horizontal or vertical axis of the projected image and a Y-axis corresponding to another axis of the projected image. The optical system further includes an image projector for projecting a collimated image having an angular field of view around the optical axis. The image projector is optically coupled to the LOE to introduce the collimated image into the LOE at the coupling region as a propagating image propagating within the LOE via internal reflection at the principal outer surface. The propagating image is partially reflected by the first set of partially reflective surfaces to generate a deflected propagating image propagating within the LOE via internal reflection at the principal outer surface, wherein the in-plane component of the optical axis of the deflected propagating image is tilted relative to the Y-axis.

[0093] 9. An optical system for projecting an image injected at a coupling region for viewing by a user's eye at an eye-tracking box, the image being viewed using a principal axis, the principal axis including an X-axis corresponding to a horizontal or vertical axis of the projected image, and a Y-axis corresponding to an axis of the projected image perpendicular to the X-axis, the optical system including a light-guiding optical element (LOE) formed of a transparent material, the LOE comprising:

[0094] (a) A first region comprising a first set of flat, mutually parallel partially reflective surfaces having a first orientation;

[0095] (b) A second region comprising a second set of flat, mutually parallel partially reflective surfaces having a second orientation that is not parallel to the first orientation;

[0096] (c) A set of parallel main outer surfaces extending across the first region and the second region, such that both the first set of partial reflective surfaces and the second set of partial reflective surfaces are located between the main outer surfaces.

[0097] Wherein, the second set of partially reflective surfaces forms an oblique angle with 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 from the coupled region via internal reflection at the main outer surface is deflected toward the second region.

[0098] Furthermore, the second set of partially reflective surfaces has an extension direction parallel to the main outer surface, and the extension direction has an angular offset relative to the X-axis.

[0099] 10. An optical system for projecting an image injected at a coupling region for viewing by a user's eye at an eye-tracking box, the image being viewed using a principal axis, the principal axis including an X-axis corresponding to a horizontal or vertical axis of the projected image, and a Y-axis corresponding to an axis of the projected image perpendicular to the X-axis, the optical system including a light-guiding optical element (LOE) formed of a transparent material, the LOE comprising:

[0100] (a) A first region comprising a first set of flat, mutually parallel partially reflective surfaces having a first orientation;

[0101] (b) A second region comprising a second set of flat, mutually parallel partially reflective surfaces having a second orientation that is not parallel to the first orientation;

[0102] (c) A set of parallel main outer surfaces extending across the first region and the second region, such that both the first set of partial reflective surfaces and the second set of partial reflective surfaces are located between the main outer surfaces.

[0103] Wherein, the second set of partially reflective surfaces forms an oblique angle with 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 from the coupled region via internal reflection at the main outer surface is deflected toward the second region.

[0104] The optical system further includes an image projector for projecting a collimated image having an angular field of view around an optical axis. The image projector is optically coupled to the LOE to introduce the collimated image into the LOE at the coupling region as a propagated image that propagates within the LOE via internal reflection at the main outer surface, wherein the in-plane component of the optical axis of the propagated image is tilted relative to the X-axis toward the boundary of the second region.

[0105] 11. The optical system according to claim 10, wherein the in-plane component of one end of the field of view of the propagated image is substantially parallel to the X-axis.

[0106] 12. An optical system for projecting an image injected at a coupling region for viewing by a user's eye at an eye-tracking box, the image being viewed using a principal axis, the principal axis including an X-axis corresponding to a horizontal or vertical axis of the projected image, and a Y-axis corresponding to an axis of the projected image perpendicular to the X-axis, the optical system including a light-guiding optical element (LOE) formed of a transparent material, the LOE comprising:

[0107] (a) A first region comprising a first set of flat, mutually parallel partially reflective surfaces having a first orientation;

[0108] (b) A second region comprising a second set of flat, mutually parallel partially reflective surfaces having a second orientation that is not parallel to the first orientation;

[0109] (c) A set of parallel main outer surfaces extending across the first region and the second region, such that both the first set of partial reflective surfaces and the second set of partial reflective surfaces are located between the main outer surfaces.

[0110] Wherein, the second set of partially reflective surfaces forms an oblique angle with 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 from the coupled region via internal reflection at the main outer surface is deflected toward the second region.

[0111] The optical system further includes an image projector for projecting a collimated image having an angular field of view around the optical axis. The image projector is optically coupled to the LOE to introduce the collimated image into the LOE at the coupling region as a propagated image propagating within the LOE via internal reflection at the main outer surface. The propagated image is partially reflected by the first set of partially reflective surfaces to generate a deflected propagated image propagating within the LOE via internal reflection at the main outer surface, wherein the in-plane component of the optical axis of the deflected propagated image is tilted relative to the Y-axis.

[0112] 13. The optical system according to any one of claims 5 to 12, wherein the eye-tracking box is defined by at least one straight line parallel to the X-axis.

[0113] 14. The optical system according to any one of claims 5 to 12, wherein the projected image is a rectangular image having edges parallel to the X-axis and the Y-axis.

[0114] 15. The optical system according to any one of claims 5 to 12 further includes a support device configured to support the LOE relative to the user's head, wherein one of the main outer surfaces faces the user's eye and is oriented horizontally relative to the user's eye, such that the X-axis is horizontally oriented.

[0115] 16. The optical system according to any one of claims 5 to 12, wherein the first region and the second region are separated by a boundary extending parallel to the X-axis.

[0116] 17. An optical system for guiding an image illumination injected at a coupling 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:

[0117] (a) A first region comprising a first set of flat, mutually parallel partially reflective surfaces having a first orientation;

[0118] (b) A second region comprising a second set of flat, mutually parallel partially reflective surfaces having a second orientation that is not parallel to the first orientation;

[0119] (c) A set of parallel main outer surfaces extending across the first region and the second region, such that both the first set of partial reflective surfaces and the second set of partial reflective surfaces are located between the main outer surfaces.

[0120] Wherein, the second set of partially reflective surfaces forms an oblique angle with 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 from the coupled region via internal reflection at the main outer surface is deflected toward the second region.

[0121] Furthermore, the first set of partial reflective surfaces has a non-uniform spacing, such that the spacing between adjacent partial reflective surfaces closer to the coupling region is smaller than the spacing between adjacent partial reflective surfaces farther from the coupling region.

[0122] 18. An optical system for guiding an image illumination injected at a coupling 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:

[0123] (a) A first region comprising a first set of flat, mutually parallel partially reflective surfaces having a first orientation;

[0124] (b) A second region comprising a second set of flat, mutually parallel partially reflective surfaces having a second orientation that is not parallel to the first orientation;

[0125] (c) A set of parallel main outer surfaces extending across the first region and the second region, such that both the first set of partial reflective surfaces and the second set of partial reflective surfaces are located between the main outer surfaces.

[0126] Wherein, the second set of partially reflective surfaces forms an oblique angle with 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 from the coupled region via internal reflection at the main outer surface is deflected toward the second region.

[0127] The optical system further includes an image projector for projecting a collimated image having an angular field of view around an optical axis. The image projector is optically coupled to the LOE to introduce the collimated image into the LOE at the coupling region as a propagating image propagating within the LOE via internal reflection at the primary outer surface. The propagating image is partially reflected by a first set of partially reflective surfaces to generate a deflected propagating image propagating within the LOE via internal reflection at the primary outer surface. The deflected propagating image is partially reflected by a second set of partially reflective surfaces to generate an outgoing image pointing outward from one of the primary outer surfaces toward the eye-tracking box. The optical axis of the outgoing image is tilted relative to the normal of the primary outer surface and has a non-zero tilt component along the in-plane extension direction of the second set of partially reflective surfaces.

[0128] It should be understood that the above description is intended to be illustrative only, and many other embodiments are possible within the scope of the invention as defined in the appended claims.

Claims

1. A head-mounted display for displaying images to a user's eyes, the head-mounted display comprising: (a) A light guide structure formed of a transparent material, the light guide structure having a pair of parallel main surfaces for supporting the propagation of light through internal reflections at the pair of main surfaces within the light guide structure; (b) A support device for supporting the light guide structure on the user's head, wherein one of the pair of main surfaces faces the user's eye, and the horizontal axis of the light guide structure is parallel to the line between the user's pupils; and (c) An image projector optically coupled to the light guide structure to introduce light corresponding to a collimated image for propagation in a first direction within the light guide structure via internal reflection at the pair of main surfaces. The light guide structure includes a first set of parallel, flat, partially reflective inner surfaces located between the pair of main surfaces and a second set of parallel, flat, partially reflective inner surfaces located between the pair of main surfaces. The first set of partially reflective inner surfaces is configured to gradually deflect light propagating in a first direction to propagate in a second direction within the light guide structure via internal reflection at the pair of main surfaces. The second set of partially reflective inner surfaces is configured to gradually deflect light propagating in the second direction to couple out from the light guide structure toward the user's eye. Furthermore, most of both the first group of partially reflective inner surfaces and the second group of partially reflective inner surfaces are located within the viewing area of ​​the light guide structure, allowing the user's eye to view distant scenes through the viewing area; Furthermore, the second set of partially reflective inner surfaces has an elongation direction corresponding to the intersection line between the plane of one of the partially reflective inner surfaces of the second set of partially reflective inner surfaces and one of the main surfaces of the pair of main surfaces, the elongation direction being inclined to the horizontal axis of the light guide structure.

2. An optical system for guiding light corresponding to a collimated image projected by a projector into a form visible to a user's eye, the optical system comprising: (a) A first light guide portion having parallel, flat front and rear main outer surfaces, the front and rear main outer surfaces supporting the propagation of light within the first light guide portion via internal reflection at the front and rear main outer surfaces, the first light guide portion being surrounded by a set of edges including a flat lower edge, the first light guide portion including a set of mutually parallel, flat internal partial reflective surfaces, the internal partial reflective surfaces being oriented such that light propagating within the first light guide portion via internal reflection with the in-plane component along a first direction is gradually deflected by the partial reflective surfaces to propagate within the first light guide portion via internal reflection with the in-plane component along a second direction, the second direction not being parallel to the first direction; (b) A second light guide portion optically coupled to the first light guide portion at the flat lower edge to form a continuation of the first light guide portion, the second light guide portion having parallel, flat front main outer surface and rear main outer surface, the front main outer surface and rear main outer surface of the second light guide portion being a continuation of the front main outer surface and the rear main outer surface of the first light guide portion, the second light guide portion having a set of mutually parallel, flat internal portion reflective coupling surfaces obliquely inclined relative to the front main outer surface and the rear main outer surface, wherein the second light guide portion has a width in a direction parallel to the flat lower edge, the width of the second light guide portion gradually decreasing with increasing distance from the flat lower edge; Furthermore, in the second light guide portion, the internal partial reflective coupling surface has an elongation direction corresponding to the intersection line between the plane of one of the internal partial reflective coupling surfaces and one of the main outer surfaces of the front and rear main outer surfaces, the elongation direction being inclined to a horizontal axis, wherein the horizontal axis is parallel to the line between the user's pupils.

3. A head-mounted display for displaying images to a user's eyes, the head-mounted display comprising: (a) A light guide structure formed of a transparent material, the light guide structure having a pair of parallel main surfaces for supporting the propagation of light through internal reflections at the pair of main surfaces within the light guide structure; (b) A support device for supporting the light guide structure on the user's head, wherein one of the pair of main surfaces faces the user's eye, and the horizontal axis of the light guide structure is parallel to the line between the user's pupils; and (c) An image projector optically coupled to the light guide structure to introduce light corresponding to a collimated image for propagation in a first direction within the light guide structure via internal reflection at the pair of main surfaces. The light guide structure includes a first set of parallel, flat, partially reflective inner surfaces located between the pair of main surfaces and a second set of parallel, flat, partially reflective inner surfaces located between the pair of main surfaces. The first set of partially reflective inner surfaces is configured to gradually deflect light propagating in a first direction to propagate in a second direction within the light guide structure via internal reflection at the pair of main surfaces. The second set of partially reflective inner surfaces is configured to gradually deflect light propagating in the second direction to couple out from the light guide structure toward the user's eye. Furthermore, the second set of partially reflective inner surfaces has an elongation direction corresponding to the intersection line between the plane of one of the partially reflective inner surfaces of the second set of partially reflective inner surfaces and one of the main surfaces of the pair of main surfaces, the elongation direction being inclined to the horizontal axis of the light guide structure.

4. The head-mounted display according to claim 3, wherein, The first set of partially reflective inner surfaces are angled such that the second direction is perpendicular to the elongation direction of the second set of partially reflective inner surfaces.

5. A display for displaying an image to a user's eyes, the display comprising: (a) A light guide structure formed of a transparent material, the light guide structure having a pair of parallel main surfaces defining a plate-shaped light guide that supports the propagation of light through internal reflections at the pair of main surfaces within the light guide structure; and (b) An image projector optically coupled to the light guide structure via a coupling device to introduce light corresponding to a collimated image into the light guide structure for propagation in a first direction via internal reflection at the pair of main surfaces. The light guide structure includes a first set of parallel, flat, partially reflective inner surfaces located between the pair of main surfaces and a second set of parallel, flat, partially reflective inner surfaces located between the pair of main surfaces. The first set of partially reflective inner surfaces is configured to gradually deflect light propagating in a first direction to propagate in a second direction within the light guide structure via internal reflection at the pair of main surfaces. The second set of partially reflective inner surfaces is configured to gradually deflect light propagating in the second direction to couple out from the light guide structure toward the user's eye. Furthermore, the image projector projects a rectangular collimated image having an angular extension about a first axis corresponding to the width of the collimated image and an angular extension about a second axis corresponding to the height of the collimated image, and wherein the rotational orientation of the image projector and / or the coupling device causes the collimated image to propagate along the first direction within the light guide structure when neither the first axis nor the second axis is parallel to the main surface of the light guide structure.

6. The display according to claim 5, wherein, The orientation of the image projector and the first set of partially reflective inner surfaces and the second set of partially reflective inner surfaces is such that light coupled from the light guide structure toward the user's eye is tilted at an offset angle relative to the normal of the pair of main surfaces, having a non-zero tilt component along the extension direction of the second set of partially reflective inner surfaces, the extension direction corresponding to the intersection between the partially reflective inner surfaces and a plane parallel to the pair of main surfaces.

7. The display according to claim 6, further comprising a support device for supporting the light guide structure on the user's head, wherein, One of the pair of main surfaces faces the user's eye, and the offset angle corrects the facial curvature angle of the light guide structure relative to the user's eye.

8. The display according to claim 6, further comprising a support device for supporting the light guide structure on the user's head, wherein, One of the pair of main surfaces faces the user's eye, and the offset angle provides a convergence angle for the image viewed by the user's eye.

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