Optical system including a two-dimensional expanding light guide optical element

Abstract

Improvements are needed in the optical system to direct image illumination towards the eye movement box for user viewing. [Solution] The optical system provides a two-stage magnification of the input optical aperture for a display based on a light guide optical element. The first magnification is achieved using two separate sets of mutually parallel partial reflective surfaces, each set passing through a different portion of the overall field of view presented to the eye. In some cases, a single image projector provides image illumination to two sets of facets integrated into the LOE. In other cases, two separate projectors deliver image illumination to their respective sets of facets, corresponding to two different portions of the field of view.

Description

Technical Field

[0001] The present invention relates to an optical system, and more particularly to an optical system including a light guiding optical element (LOE) for achieving optical aperture expansion.

Background Art

[0002] Many near-eye display systems include a transparent light guiding optical element (LOE) or "waveguide" placed in front of the user's eye, which transmits an image within the LOE by internal reflection and then externally couples the image towards the user's eye by means of a suitable output coupling mechanism. The output coupling mechanism may be based on an embedded partial reflector or "facet", or may use a diffractive element. The following description mainly refers to facet-based external coupling configurations.

Summary of the Invention

[0003] The present invention is an optical system for directing image illumination towards an eye movement box for viewing by a user's eye.

[0004] According to the teaching of embodiments of the present invention, an optical system for directing image illumination injected into at least one internal coupling region to an eye movement box for viewing by the user's eye, comprising a light guide optical element (LOE) formed of a transparent material, wherein the LOE comprises: (a) a first region comprising a first set of mutually parallel partial reflective surfaces of planes having a first orientation; (b) a second region comprising a second set of mutually parallel partial reflective surfaces of planes having a second orientation nonparallel to the first orientation; (c) a second region comprising a third set of mutually parallel partial reflective surfaces of planes having a third orientation nonparallel to each of the first and second orientations; and (d) a set of mutually parallel main outer surfaces comprising the first partial reflective surface An optical system is provided, comprising a set of mutually parallel main outer surfaces, the main outer surfaces extending across first and second regions, such that the main outer surfaces are all located between the main outer surfaces, and each of the first and second sets of partial reflective surfaces is oriented such that the third set of partial reflective surfaces is at an oblique angle to the main outer surfaces, and each of the first and second sets of partial reflective surfaces is oriented such that a portion of the image illumination propagating within the LOE by internal reflection from the main outer surfaces from the first region to the second region is externally coupled from the LOE toward the eye movement box, and a portion of the image illumination propagating within the LOE by internal reflection from at least one internal coupling region is deflected toward the second region.

[0005] According to further features of embodiments of the present invention, a first set of partial reflective surfaces deflects a first portion of the field of view of an image toward a second region, and a second set of partial reflective surfaces deflects a second portion of the field of view of an image toward a second region, so that the first and second portions of the field of view combine to provide a continuous combined field of view that is larger than each of the first and second portions.

[0006] According to further features of embodiments of the present invention, each of the first and second sets of partial reflectors includes a deflection surface configured to reflect most of the image illumination incident on the deflection surface, and the deflection surface is deployed to become the first partial reflector of each of the first and second sets of partial reflectors reached by image illumination injected into at least one internal coupling region.

[0007] According to further features of embodiments of the present invention, the deflection surfaces of the first set of partial reflectors and the deflection surfaces of the second set of partial reflectors intersect in a straight line.

[0008] According to further features of embodiments of the present invention, each of the first and second sets of partial reflectors includes a filler surface adjacent to the deflection surface, the filler surface having a length measured parallel to the main outer surface that is shorter than the length of the deflection surface and shorter than the length of another partial reflector adjacent to the filler surface.

[0009] According to further features of embodiments of the present invention, the first and second sets of partial reflective surfaces each have non-uniform spacing between them.

[0010] According to further features of embodiments of the present invention, each of the first and second sets of partial reflective surfaces has a length measured parallel to the main outer surface, and each of the first and second sets of partial reflective surfaces includes partial reflective surfaces having different lengths.

[0011] According to further features of embodiments of the present invention, the internal bonding region is located in the middle third of the LOE dimensions.

[0012] According to further features of embodiments of the present invention, at least one edge of the LOE adjacent to a first region of the LOE is implemented as a mirror surface perpendicular to the main outer surface, and the path of image illumination from the internal bonding region of the LOE to the second region includes at least one reflection from the mirror surface of at least one edge of the LOE.

[0013] According to further features of embodiments of the present invention, an image projector is also provided which is configured to project image illumination corresponding to a collimated image, the image projector being optically coupled to the LOE in an internal coupling region to inject the image illumination into a first region of the LOE so that it propagates within the LOE by internal reflections on the main outer surface, the image illumination being injected with an effective optical aperture and an effective propagation direction so that it is incident on both the partial reflective surfaces of a first set of partial reflective surfaces and a second set of partial reflective surfaces.

[0014] According to further features of embodiments of the present invention, the dimensions of a first set of partial reflectors perpendicular to the effective propagation direction are greater than the dimensions of a second set of partial reflectors perpendicular to the effective propagation direction.

[0015] According to further features of embodiments of the present invention, the angle formed between the first set of partial reflectors and the effective propagation direction is smaller than the angle formed between the second set of partial reflectors and the effective propagation direction.

[0016] A further feature of the embodiments of the present invention is also provided, a first image projector configured to project image illumination corresponding to a first portion of a collimated image, the first image projector being optically coupled to the LOE in a first internal coupling region to inject image illumination into a first region of the LOE such that it propagates within the LOE by internal reflections on a major outer surface and incident on partial reflective surfaces of a first set of partial reflective surfaces, and a second image projector being configured to project image illumination corresponding to a second portion of a collimated image, the second image projector being optically coupled to the LOE in a second internal coupling region to inject image illumination into a first region of the LOE such that it propagates within the LOE by internal reflections on a major outer surface and incident on partial reflective surfaces of a second set of partial reflective surfaces, so that the first and second portions of the collimated image are combined in an eye movement box to provide a combined image.

[0017] According to further features of embodiments of the present invention, the first and second sets of partial reflective surfaces are perpendicular to the main outer surface of the LOE.

[0018] According to further features of embodiments of the present invention, the first and second sets of partial reflective surfaces are oblique to the main outer surface of the LOE.

[0019] According to the teaching of embodiments of the present invention, an optical system for delivering an image to an eye movement box for viewing by the user's eye is also provided, the optical system being (a) a light guide optical element (LOE) formed from a transparent material, comprising an external coupling set of mutually parallel partial reflective surfaces and a set of mutually parallel main outer surfaces, wherein the external coupling set of partial reflective surfaces is located between the main outer surfaces; (b) a first image projector configured to project image illumination corresponding to a first portion of a collimated image from an optical aperture, the first image projector following a first optical path from the optical aperture to the LOE such that the image illumination propagates within the LOE by internal reflection from the main outer surfaces and is progressively externally coupled from the LOE toward the eye movement box by the external coupling set of partial reflective surfaces; and (c) a second image projector configured to project image illumination corresponding to a second portion of a collimated image from an optical aperture, wherein the image illumination is (d) a first optical magnification component comprising (d) a first optical magnification component comprising (e) a second optical magnification component comprising a second set of mutually parallel partial reflective surfaces having a first orientation, which is deployed in the first optical path to the optical aperture and (e) a second optical magnification component comprising a second set of mutually parallel partial reflective surfaces having a second orientation, which is deployed in the second optical path to magnify the optical aperture of the second image projector and direct the image light toward the externally coupled set of partial reflective surfaces.

[0020] According to further features of embodiments of the present invention, the first optical magnification component and the second optical magnification component are external components optically coupled to the LOE, and the injection of image illumination from the first and second image projectors into the LOE occurs via the first and second optical magnification components, respectively.

[0021] According to further features of embodiments of the present invention, the first and second optical magnification components are each mounted on a slab having two main surfaces, one of which is optically coupled to an internal coupling surface associated with the LOE.

[0022] According to further features of embodiments of the present invention, the internal bonding surface is angled obliquely with respect to the main outer surface of the LOE.

[0023] According to further features of embodiments of the present invention, the slab of the first optical magnification component is optically coupled to a first internal bonding surface associated with the LOE, and the slab of the second optical magnification component is optically coupled to a second internal bonding surface associated with the LOE, and the first and second internal bonding surfaces are non-coplanar.

[0024] According to further features of embodiments of the present invention, the internal bonding surface is coplanar or parallel to one of the main outer surfaces of the LOE, and the LOE includes at least one partial reflection internal bonding surface.

[0025] According to further features of embodiments of the present invention, a first set of partial reflective surfaces and a second set of partial reflective surfaces are located within the LOE between the main outer surfaces of the LOE.

[0026] According to further features of embodiments of the present invention, the first and second sets of partial reflective surfaces are perpendicular to the main outer surface of the LOE.

[0027] According to further features of embodiments of the present invention, the first and second sets of partial reflective surfaces are oblique to the main outer surface of the LOE.

[0028] According to a further feature of an embodiment of the present invention, the first optical enlarging component further includes a third set of mutually parallel partial reflection surfaces that are non-parallel to the first set of partial reflection surfaces, and the first and third sets of partial reflection surfaces enlarge the optical aperture of the first image projector in opposite directions and direct the image light towards the external coupling set of partial reflection surfaces.

[0029] According to a further feature of an embodiment of the present invention, the first image projector has a central optical axis, and the third set of partial reflection surfaces has an inclination with respect to the central optical axis that is different from the inclination of the first set of partial reflection surfaces with respect to the central axis. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The present invention is described herein by way of example only with reference to the accompanying drawings.

[0031] [Figure 1A] Schematic isometric views of optical systems implemented using a light guiding optical element (LOE), constructed and operable in accordance with the teachings of the first aspect of the present invention, showing a downward configuration and a side injection configuration, respectively. [Figure 1B] Schematic isometric views of optical systems implemented using a light guiding optical element (LOE), constructed and operable in accordance with the teachings of the first aspect of the present invention, showing a downward configuration and a side injection configuration, respectively. [Figure 1C] Schematic isometric views of optical systems implemented using a light guiding optical element (LOE), constructed and operable in accordance with the teachings of a further aspect of the present invention using two image projectors per display, showing a downward configuration and a side injection configuration, respectively. [Figure 1D] Schematic isometric views of optical systems implemented using a light guiding optical element (LOE), constructed and operable in accordance with the teachings of a further aspect of the present invention using two image projectors per display, showing a downward configuration and a side injection configuration, respectively. [Figure 2] Schematic plan view of an LOE configuration for implementing the optical systems of FIGS. 1A and 1B. [Figure 3] Figure 2 is a schematic enlarged view of the first region of the LOE, illustrating various geometric considerations for determining the desired spacing and development of the partial reflective surfaces in the first region of the LOE. [Figure 4] Figure 2 is a schematic enlarged view of the first region of the LOE, illustrating various geometric considerations for determining the desired spacing and development of the partial reflective surfaces in the first region of the LOE. [Figure 5] Figure 2 is a schematic enlarged view of the first region of the LOE, illustrating various geometric considerations for determining the desired spacing and development of the partial reflective surfaces in the first region of the LOE. [Figure 6] Figure 2 is a schematic enlarged view of the first region of the LOE, illustrating various geometric considerations for determining the desired spacing and development of the partial reflective surfaces in the first region of the LOE. [Figure 7] Figure 2 is a schematic enlarged view of the first region of the LOE, illustrating various geometric considerations for determining the desired spacing and development of the partial reflective surfaces in the first region of the LOE. [Figure 8] Figure 2 is a schematic diagram of an alternative implementation of LOE. [Figure 9] Figure 2 is a further schematic diagram of the LOE, showing the coupling of the image projector and the LOE via a wedge prism. [Figure 10A] These are schematic diagrams of the relative unfolding of the partial reflective surfaces within the LOE in Figure 2, showing a symmetrical configuration, an eccentric internal coupling region, and an asymmetrical inclination of the surfaces, respectively. [Figure 10B] These are schematic diagrams of the relative unfolding of the partial reflective surfaces within the LOE in Figure 2, showing a symmetrical configuration, an eccentric internal coupling region, and an asymmetrical inclination of the surfaces, respectively. [Figure 10C] These are schematic diagrams of the relative unfolding of the partial reflective surfaces within the LOE in Figure 2, showing a symmetrical configuration, an eccentric internal coupling region, and an asymmetrical inclination of the surfaces, respectively. [Figure 11] Combining the geometric considerations presented in Figures 3 to 7, a particularly preferred implementation of the first region of the LOE in Figure 2, using variable-length facets, is shown. [Figure 12A]Figure 2 is a schematic diagram of a further modified implementation of the LOE, in which the first and second sets of partial reflective surfaces are subdivided between the two segments of the LOE. [Figure 12B] Figure 2 is a schematic diagram of a further modified implementation of the LOE, in which the first and second sets of partial reflective surfaces are subdivided between the two segments of the LOE. [Figure 13] This is a schematic diagram of a further modified implementation form of the LOE shown in Figure 2, which uses the peripheral mirror surface. [Figure 14A] Figures 1C and 1D are schematic isometric views of the LOE configuration for implementing the optical system shown in Figures 1C and 1D. [Figure 14B] Figure 14A is a schematic diagram of the overall field of view subdivision between the two image projectors from the optical system. [Figure 15A] Figure 14A is an enlarged schematic isometric view of the LOE from the optical system, showing an implementation that uses orthogonal and obliquely angled partial reflectors, respectively, for the first optical aperture enlargement. [Figure 15B] Figure 14A is an enlarged schematic isometric view of the LOE from the optical system, showing an implementation that uses orthogonal and obliquely angled partial reflectors, respectively, for the first optical aperture enlargement. [Figure 16A] This is a side view of an alternative implementation of an optical system according to one aspect of the present invention, in which the first expansion of the optical aperture is performed using an aperture expansion component outside the LOE. [Figure 16B] Figure 16A shows the optical system taken along the lines of sight marked V1, V2, V3, and V4, respectively. [Figure 16C] Figure 16A shows the optical system taken along the lines of sight marked V1, V2, V3, and V4, respectively. [Figure 16D] Figure 16A shows the optical system taken along the lines of sight marked V1, V2, V3, and V4, respectively. [Figure 16E] Figure 16A shows the optical system taken along the lines of sight marked V1, V2, V3, and V4, respectively. [Figure 17] Figures 14A to 16E are schematic diagrams of a dual image projector assembly for use in the optical system. [Figure 18] The optical aperture expansion component of each image projector is a magnified schematic isometric view of a modified implementation of the LOE from the optical system in Figure 14A, which uses two sets of partial reflective surfaces. [Figure 19A] Figure 16A is an isometric view of a modified optical system, showing three options for optical coupling of the optical aperture expanding component with the LOE, using two sets of partial reflective surfaces for each image projector. [Figure 19B] Figure 16A is an isometric view of a modified optical system, showing three options for optical coupling of the optical aperture expanding component with the LOE, using two sets of partial reflective surfaces for each image projector. [Figure 19C] Figure 16A is an isometric view of a modified optical system, showing three options for optical coupling of the optical aperture expanding component with the LOE, using two sets of partial reflective surfaces for each image projector. [Figure 20A] Figure 16A shows front, top, and side views, respectively, of further modifications of the optical system, illustrating the optical coupling of the optical aperture expansion component to the main outer surface of the LOE. [Figure 20B] Figure 16A shows front, top, and side views, respectively, of further modifications of the optical system, illustrating the optical coupling of the optical aperture expansion component to the main outer surface of the LOE. [Figure 20C] Figure 16A shows front, top, and side views, respectively, of further modifications of the optical system, illustrating the optical coupling of the optical aperture expansion component to the main outer surface of the LOE. [Figure 21A] Figures 20A to 20C show the top view, front view, and side view of the optical aperture enlargement component in a modified mounting configuration of the optical system. [Figure 21B] Figures 20A to 20C show the top view, front view, and side view of the optical aperture enlargement component in a modified mounting configuration of the optical system. [Figure 21C] Figures 20A to 20C show the top view, front view, and side view of the optical aperture enlargement component in a modified mounting configuration of the optical system. [Figure 22A] Figures 21A to 21C show the side view, top view, and front view, respectively, of an optical system using the optical aperture enlargement component. [Figure 22B] Figures 21A to 21C show the side view, top view, and front view, respectively, of an optical system using the optical aperture enlargement component. [Figure 22C] Figures 21A to 21C show the side view, top view, and front view, respectively, of an optical system using the optical aperture enlargement component. [Modes for carrying out the invention]

[0032] This invention is an optical system for directing image illumination onto an eye movement box for viewing with the user's eyes.

[0033] The principle and operation of the optical system according to the present invention can be better understood by referring to the drawings and accompanying description.

[0034] As a preface, particular aspects of the present invention relate to an optical system for directing image illumination via a light guide optical element (LOE) to an eye movement box (EMB) for viewing by the user's eye. The optical system provides optical aperture magnification for the purpose of a head-up display, most preferably a near-eye display, which may be a virtual reality display or more preferably an augmented reality display. The optical system preferably provides two-stage magnification of an input optical aperture, the first magnification being achieved using two separate sets of mutually parallel partial reflective surfaces ("facets"), each set passing through different (not identical, but preferably overlapping) portions of the overall field of view (FOV) presented to the eye. In a first subset of embodiments (Figures 1A, 1B, and 2-13), the optical system uses a single image projector ("POD") that provides image illumination to two sets of facets integrated into the LOE. In a second subset of the embodiment, two separate PODs deliver image illumination to their respective sets of facets, corresponding to two different (but not identical, preferably overlapping) portions of the FOV. In the latter case, the first magnification may use a set of facets that is either outside the LOE (Figures 16A–16D and 19A–22C) or integrated as part of the LOE (Figures 1C, 1D, 14A–15B, and 18) and is part of the corresponding magnification component. These various subsets of the non-limiting embodiment are each discussed separately below.

[0035] Collectively referring to various embodiments using facets integrated with the LOE (e.g., Figures 1A–1D), these all represent optical systems for directing image illumination injected into at least one internal coupling region to an eye movement box for viewing by the user's eye. Generally, the optical system includes a light guide optical element (LOE) 12 formed from a transparent material and includes a first region 16 including a first set of mutually parallel partial reflective surfaces ("facets") of a plane having a first orientation and a second set of mutually parallel partial reflective surfaces ("facets") of a plane having a second orientation nonparallel to the first orientation. (The facets are not visible in Figures 1A–1D but are schematically shown in the drawings below.) The LOE also includes a second region 18 including a third set of mutually parallel partial reflective surfaces (or "facets," also called "external coupling surfaces") of a plane having a third orientation nonparallel to each of the first and second orientations. The LOE is bounded by a set of mutually parallel primary outer surfaces extending across the first and second regions, such that the first, second, and third sets of partial reflective surfaces are all located between the primary outer surfaces.

[0036] A third set of partial reflective surfaces is positioned at an oblique angle to the main outer surface so that a portion of the image illumination propagating within the LOE by internal reflection from the main outer surface from the first region to the second region is externally coupled from the LOE toward the eye movement box for viewing by the user's eye. Each of the first and second sets of partial reflective surfaces is oriented so that a portion of the image illumination propagating within the LOE by internal reflection from at least one internal coupling region toward the second region.

[0037] Most preferably, each of the first and second sets of facets considers aperture enlargement of a distinct portion of the entire field of view. Specifically, the first set of partial reflective surfaces preferably deflects the first portion of the field of view of the image toward a second region, and the second set of partial reflective surfaces deflects the second portion of the field of view of the image toward a second region, so that the first and second portions of the field of view combine to provide a continuous combined field of view that is larger than each of the first and second portions of the FOV. The two portions of the FOV preferably substantially correspond to two sides (left and right or up and down) of the entire FOV, but correspond to an acceptable range of pupil positions of the observer on which the display is designed such that the central regions sufficiently overlap to ensure complete and continuous coverage of the central field of view across the eye movement box.

[0038] An exemplary implementation of the present invention envisions a form of near-eye display, generally designated 10, that uses an LOE 12. A compact image projector (or "POD") 14 is optically coupled to inject an image into the LOE 12 (in other words, referred to as the "waveguide," "substrate," or "slab"), within the LOE 12, where the image light is captured in one dimension by internal reflections on the main outer surface of the plane. The light collides with a first set and a second set of partial reflective surfaces (in other words, referred to as "facets"), each set of facets inclined obliquely with respect to the propagation direction of the image light, and each consecutive facet deflects a portion of the image light in the deflection direction, which is then captured / guided by internal reflections within the substrate. These first and second sets of facets are located in a first region of the LOE, designated 16, although they are not shown individually in Figures 1A–1D. This partial reflection at consecutive facets achieves a one-dimensional optical aperture expansion.

[0039] The first and second sets of partial reflective surfaces located in region 16 deflect the image illumination from a first propagation direction captured by total internal reflection (TIR) ​​within the substrate to a second propagation direction, also captured by TIR within the substrate. This partial reflection across consecutive facets achieves one dimension of optical aperture expansion. In Figures 1C and 1D, two image projectors 14 are provided to each display, and the image illumination of each is amplified by corresponding sets of partial reflective surfaces in region 16.

[0040] Next, the deflected image illumination passes through a second substrate region 18, which may be implemented as an adjacent separate substrate or as an extension of a single substrate, where an external coupling configuration (either a further set of partial reflective facets or a diffractive optical element) progressively externally couples a portion of the image illumination toward the observer's eye located within a region defined as the eye movement box (EMB), thus achieving two dimensions of optical aperture expansion. The entire device may be implemented separately for each eye, preferably supported against the user's head so that each LOE 12 faces the user's corresponding eye. In one particularly preferred option, as shown here, the support configuration is implemented as an eyeglass frame with sides 20 for supporting the device toward the user's ears. Other forms of support configurations may also be used, including but not limited to devices suspended from a headband, visor, or helmet.

[0041] In this specification, in the drawings and claims, the X-axis extends horizontally (Figures 1A and 1C) or vertically (Figures 1B and 1D) in the general extending direction of the first region of the LOE, and the Y-axis extends perpendicularly thereto, i.e., vertically in Figures 1A and 1C, and horizontally in Figures 1B and 1D.

[0042] Very broadly speaking, the first region 16 of the first LOE or LOE12 can be considered to achieve aperture expansion in the X direction, while the second region 18 of the second LOE or LOE12 achieves aperture expansion in the Y direction. Details of the angular spread of the different parts of the field of view are described more precisely below. The orientations shown in Figures 1A and 1C can be considered a “downward” configuration, in which image illumination entering the main (second region) of the LOE enters from the top, while the orientations shown in Figures 1B and 1D can be considered a “side-point” configuration, where the axis referred to as the Y-axis is horizontally extended. In the remaining drawings, various features of specific embodiments of the invention are shown in the context of the “downward” orientation, as in Figures 1A and 1C. However, it should be understood that all of these features are equally applicable to the side-point configuration, which is also within the scope of the invention. In specific cases, other intermediate orientations are also applicable and are included within the scope of the invention unless expressly excluded.

[0043] In a first set of preferred but non-limiting examples of the present invention, the aforementioned set of facets is perpendicular to the main outer surface of the substrate. In this case, both the injected image and its conjugate, which undergoes internal reflection as it propagates within region 16, are deflected, resulting in a conjugate image that propagates in the deflected direction. In an alternative set of preferred but non-limiting examples, the first and second sets of partial reflectors are angled obliquely to the main outer surface of the LOE. In the latter case, either the injected image or its conjugate forms the desired deflected image propagating within the LOE, while other reflections can be minimized, for example, by using angle-selective coatings on the facets that make them relatively transparent for a range of incident angles presented by images for which reflection is not desired.

[0044] The POD used in the device of the present invention is preferably configured to generate a collimated image, that is, in the collimated image, the light from each image pixel is a parallel beam collimated to infinity in the angular direction corresponding to the pixel's position. Thus, the image illumination extends over an angular range corresponding to the two-dimensional field of view.

[0045] The image projector 14 typically includes at least one light source deployed to illuminate a spatial light modulator, such as an LCOS chip. The spatial light modulator modulates the projection intensity of each pixel of the image, thereby generating the image. Alternatively, the image projector may include a scanning configuration, typically implemented using a fast scanning mirror, which scans the illumination from the laser light source across the image plane of the projector, while the beam intensity changes pixel by pixel in synchronous motion, thereby projecting the desired intensity onto each pixel. In either case, a collimating optical system is provided to produce an output projected image that is collimated to infinity. Some or all of the above components are typically arranged on the surface of one or more polarizing beam splitter (PBS) cubes or other prism configurations, as is well known in the art.

[0046] The optical coupling of the image projector 14 and the LOE 12 can be achieved by any suitable optical coupling, such as via a coupling prism having an obliquely angled input surface or via a reflective coupling configuration, through one of the side edges and / or main outer surfaces of the LOE. Details of the internal coupling configuration are not important to the present invention and are schematically shown here as a non-limiting example of a wedge prism 15 applied to the main outer surface of the LOE.

[0047] It will be understood that the near-eye display 10 includes various additional components, typically including a controller 22 for operating an image projector 14, which typically employs power from a small onboard battery (not shown) or some other suitable power source. It will be understood that the controller 22 includes all necessary electronic components, such as at least one processor or processing circuit, for driving the image projector, as is well known in the art.

[0048] The jointly assigned PCT patent application publication WO2020 / 049542A1 (hereinafter referred to as "'542 Publication") is referenced, which is unpublished as of the priority date of this application and is not prior art, but is incorporated herein by reference to its entirety as if it were fully described herein. All features of the present invention not otherwise specified should be understood to be as described in '542 Application.

[0049] A first aspect of the present invention differs from the configuration described in the '542 publication in that the first region 16 of the LOE hereof comprises not just one, as described in the '542 publication, but two separate sets of partial reflective facets, typically in different (non-parallel) orientations, each of which independently directs different portions of the image field of view toward the second LOE region 18 for external coupling toward the eye movement box. Such a configuration is implied by two opposite-direction arrows in Figures 1A and 1B and is schematically shown in Figure 2.

[0050] Specifically, in the non-limiting but preferred example shown in Figure 2, the POD 14 injects an image into a first region 16 of the LOE near the middle of the LOE's dimensions (typically within the middle third). The injected image is then partially reflected by two sets of partial reflective surfaces 161 and 162 so as to expand the image in the opposite direction along the X-axis and progressively deflect from consecutive facets toward a second region of the LOE, where it is progressively externally coupled toward the eye movement box by either a further set of inclined partial reflective facets or a diffractive optical element for observation by the observer.

[0051] The first facet of each of the first two sets of partial reflective surfaces is preferably a deflection surface (or referred to as an "internally coupled facet") having a relatively high reflectivity that reflects more than half, typically at least 80%, of the image illumination incident on the facet. Subsequent facets in each set preferably have a lower reflectivity (usually except the last facet) and may tend to increase reflectively and progressively from facet to facet, such as 25%, 33%, 50%, and 100%, thereby compensating for the progressive decrease in illumination intensity reaching successive facets and thereby providing a relatively uniform intensity output.

[0052] The use of two sets of facets that expand the optical aperture in opposite directions from an internal coupling region near the midpoint of the LOE dimensions can, in certain embodiments, shorten the optical path length from the projector to the eye movement box, and thereby reduce the overall required dimensions of the device to provide a given field of view to the observer, compared to the configuration of the aforementioned '542 application'.

[0053] According to one particularly preferred set of implementations of the present invention, facets are implemented as “partial facets” such that the partial reflection characteristics are located only within a sub-region of the cross-sectional area of ​​a first region that includes the “imaging area” of each facet plane and preferably excludes at least the majority of the “non-imaging area” of some or all of the facets. This is shown with the various lengths of facets 161 and 162 in Figure 2. The active (partial reflection) area of ​​a facet is preferably enlarged slightly beyond the minimum required to complete the geometric requirements of the EMB image projection in order to avoid anomalies that may be caused by defects at the edges of the coating, and the facets may also be further enlarged in some cases for additional considerations regarding integer overlaps between facets in the deflected image direction in order to achieve improved image uniformity.

[0054] If a first region is formed from a stack of coated plates and then cut at an appropriate angle (for example, as described in PCT Patent Publication WO2007054928A1 and known in the art), selective spatial deployment of a partial reflective surface can be advantageously achieved by forming a stack of plates in which the partial reflective coating lies on a first portion of the interface plane between the two plates, so as to form an optical continuum between the two plates, and the second portion of the interface plane is bonded (typically without coating, using an adhesive with a matching refractive index). Selective application of a partial reflective coating is typically achieved by applying a suitable masking layer before the coating process and removing the masking layer at the end of the coating process.

[0055] According to alternative manufacturing techniques, a stack of fully coated plates may be formed and then cut into the required shape for the volume containing the facets. The required form of the LOE is then completed by optically joining this irregular block containing the partially reflective facets with a complementary block of planar glass having a matching refractive index.

[0056] The optical axis is not actually parallel to the X-axis but lies in the XZ plane, and the Z component to the page is selected such that the entire range of angles of the depth dimension of the FOV is subjected to total internal reflection on the main substrate surface. As described in detail in application 542, the optical axis can also be offset from the X-axis in the Y direction to optimize the LOE design. For the sake of simplicity of presentation, the graphic representations and descriptions herein relate only to the in-plane (XY) component of the ray propagation direction, which is referred herein to as the “in-plane component” or “component parallel to the main outer surface of the LOE”.

[0057] It should be noted that some of the reflections from the left side of the field of view are lost because they are reflected from facets near the right side of the LOE in a direction that does not reach the EMB. Similarly, some of the rays from the right side of the field of view are lost because they are reflected from facets near the left side of the LOE and deflected in a direction that does not reach the EMB. Certain aspects of the present invention utilize these observations to reduce the dimensions (and therefore volume and weight) of the first LOE (or LOE region).

[0058] The distance between adjacent facets 161 and 162 depends on the FOV and the size of the entrance opening in the joining region, and must be designed to adequately replicate the entrance opening uniformly across the entire EMB without any empty space. For a given entrance opening size, a constant spacing between facets 161 or 162 results in uneven lighting, as shown in Figure 3, leading to a bright or dark "stripe" appearance. To avoid this, the distance between adjacent facets must be set using geometric considerations, as will be discussed in detail below, to minimize such a striped appearance.

[0059] As shown in Figure 4, the distance between adjacent facets should be chosen to replicate an entrance opening that is hole-free and non-overlapping. Since each facet reflects a specific subset of the full FOV, this distance needs to be optimized for the relevant subset of the FOV, and as illustrated in Figures 5-6, the distance is expected to vary between adjacent facets. However, changing the distance between adjacent facets can only minimize the effect of bright or dark stripes that start outside the internal bonding region. As schematically shown in Figure 7, the first dark “stripe” can be minimized by adding an additional facet between the first two facets, which redirects the light into the darker area.

[0060] Another embodiment of the present invention, which helps improve the uniformity of the illuminated output image across the entire EMB, is presented in Figure 8, which includes many closely spaced facets. By reducing the facet spacing by an integer compared to the above, the non-uniformity of the image is better averaged and thereby mitigated. Furthermore, since it is extremely difficult to design achromatic high-reflectivity coatings with a constant uniform reflectivity for large FOVs, it is advantageous to divide the reflectivity of the first facet into several facets, as illustrated by the gray facets in Figure 8.

[0061] Light needs to be coupled from the POD to the waveguide. One way to achieve this is to place a wedge that coincides between the optical axis of the POD's illumination system and the plane of the waveguide, as shown in Figure 9.

[0062] So far, we have discussed and presented symmetrical configurations as shown in Figure 10A. However, the two sections of facets 161 and 162 do not need to be symmetrical, and the FOVs treated by each set of facets may be different. For example, as shown in Figure 10B, it is often preferable to position the POD in a location that is not centered relative to the EMB. Also, as shown in Figure 10C, the angular orientation of the facets in the two regions may differ because the sizes of the FOVs illuminated by each section are different (in this case, the sizes of the two regions are almost always not the same), or because the azimuthal orientation of the facets in region 18 is not parallel / perpendicular to the principal axis of the FOV.

[0063] To minimize ghosting and increase efficiency, it is advantageous to use "partial facets" as described above. An implementation of this concept in the current application is schematically shown in Figure 11.

[0064] Another embodiment of the present invention is presented in Figures 12A–C, in which the two subsections of facets 161 and 162 are arranged sequentially, rather than adjacently in a side-by-side configuration as in all the figures to date. In such an embodiment, the orientation of the facets of regions 161 and 162 may be nearly opposite to each other, so that light propagates in opposite orientations (right and left in the figure) as in Figure 12A, or they may be nearly parallel, so that light from both sections propagates in the same general direction as in Figures 12B–C. In the latter configuration, the location of the internal bonding region is positioned around the edge of region 16, thereby simplifying the internal bonding structure and minimizing the effects of non-uniformity in the central FOV (principal ray). As shown in Figure 12C, the angular orientation of the facets 12A–B does not need to be identical. (Although not explicitly shown, the option to change the facet angles in the configuration of Figure 12A is also possible.)

[0065] Figure 13 presents a configuration in which the surface of the waveguide in region 16 is coated with a highly reflective coating, such as a silver coating, and facets 161 (162) are oriented so that light impacting them can be reflected by 163 (164) and then reflected back to 18, or transmitted through 161 (162), reflected at the edge 165 (166), reflected by 161 and directed back to 18. The angular orientation of 163-166 must be very precise; otherwise, a considerable amount of ghosting will be present.

[0066] Here and elsewhere in this document, the terms “trimmed” and “truncated” are used to refer to the shape or dimensions of the final product reduced relative to the theoretical starting point of the mounting configuration, typically resulting in situations where different facets have different lengths, as measurements parallel to the main outer surface of the LOE. The term does not include mounting configurations or other specific manufacturing techniques that physically cut away material. While it is not necessarily assumed that the LOE will be precisely trimmed along the boundaries of a designated area, it is assumed that these areas will provide design flexibility, allowing the LOE to be finished with any outer contour that is aesthetically pleasing and / or mechanically compatible with any additional details of the desired application.

[0067] It should be noted that the use of partial facets as described above can offer one or more advantages, including improved efficiency and brightness, as image transmission from facets further away from the internal joining region does not need to pass through so many additional facets before reaching the second LOE region. Furthermore, in some cases, omitting facets in areas not needed for image projection can avoid unwanted "ghost" reflections that can degrade image quality.

[0068] Now, looking at Figures 1C, 1D and 14A–22C, a set of further embodiments of the present invention uses two separate image projectors to provide separate portions of the entire field of view of an image displayed to the user's eye. Thus, generally according to this aspect of the present invention, the optical system 10 for delivering an image to an eye movement box for viewing by the user's eye includes a light guide optical element (LOE) 12 formed of a transparent material, which provides an external coupling of planar, mutually parallel partial reflective surfaces located between a set of mutually parallel main outer surfaces. The first image projector POD 1 is configured to project image illumination corresponding to a first portion of a collimated image from an optical aperture, and the image illumination follows a first optical path from the optical aperture to the LOE such that it propagates within the LOE by internal reflections from the main outer surfaces and is progressively externally coupled from the LOE toward the eye movement box by the external coupling set of partial reflective surfaces. A second image projector POD2 is configured to project image illumination corresponding to a second portion of the collimated image from the optical aperture, following a second optical path from the optical aperture to the LOE such that the image illumination propagates within the LOE by internal reflection from the main outer surface and is progressively externally coupled from the LOE toward the eye movement box by an external coupling set of partial reflective surfaces. Alternatively, the external coupling set of facets may be replaced by diffractive optical elements for progressively externally coupling the image illumination toward the EMB, as known in the art. The first and second portions of the collimated image are combined in the eye movement box to provide a combined image.

[0069] A particularly preferred feature of this aspect of the present invention is that the optical system further includes a first optical magnification component, which includes a first set of mutually parallel partial reflective surfaces having a first orientation and is deployed in a first optical path to enlarge the optical aperture of a first image projector and direct image light toward an externally coupled set of partial reflective surfaces. Similarly, the optical system includes a second set of mutually parallel partial reflective surfaces having a second orientation and is deployed in a second optical path to enlarge the optical aperture of a second image projector and direct image light toward an externally coupled set of partial reflective surfaces.

[0070] Figure 14B illustrates how the FOV is divided between two PODs in one non-limiting implementation of the present invention. Each POD illuminates a portion of the FOV, and together they constitute the entire FOV projected onto the observer's retina. Here, each of the two PODs is responsible for an equal-sized FOV, although, conversely, one POD may provide a larger portion of the FOV than the other. To reduce boundary artifacts, it is typically preferable to include an overlapping region in the FOV between the two PODs, as shown in the figure.

[0071] According to a first subset of these implementations, as shown in Figures 14A–15B and 18, the first and second sets of partial reflective surfaces 161 and 162 are located within the LOE 12 between the main outer surfaces of the LOE. As in previous embodiments, this implementation may use the first and second sets of partial reflective surfaces 161 and 162 that are perpendicular to the main outer surfaces of the LOE, as shown in Figures 14A and 15A. In this case, both the injected image and its conjugate, which receives internal reflection as it propagates within the region 16, are deflected, resulting in a conjugate image that propagates in the deflected direction. Alternatively, the first and second sets of partial reflective surfaces 161 and 162 may be used that are angled obliquely to the main outer surfaces of the LOE, as shown in Figure 15B. In the latter case, the injected image or its conjugate forms the desired deflected image propagating within the LOE, while other reflections can be minimized, for example, by using angle-selective coatings on the facets that make them relatively transparent to a range of incident angles presented by images for which reflection is not desired. In these implementations, the structural and design considerations for each part (e.g., half) of the first part 16 of LOE 12 are largely the same as those described in the aforementioned '542 publication.

[0072] Optionally, one or both of the PODs may have two sets of partial reflective facets in different orientations, such that one or both parts of the first portion 16 of LOE12 can be implemented according to the teachings in Figures 2 to 13 above. An example of such an implementation is schematically shown in Figure 18, in which the first image projector POD1 injects image illumination through a first optical magnification component that includes both a first set of partial reflective surfaces 161 and a third set of mutually parallel partial reflective surfaces 163 that are non-parallel to the surface 161. The first and third sets of facets 161 and 163 magnify the optical aperture of the first image projector POD1 in opposite directions along the X-axis in the same manner as described above, directing the image illumination toward the externally coupled set of partial reflective surfaces 181 of the second portion 18 of LOE12.

[0073] Preferably, the second image projector POD2 also injects image illumination through a second optical magnification component which includes both a second set of partial reflective surfaces 162 and a fourth set of mutually parallel partial reflective surfaces 164 that are non-parallel to the surface 162. The second and fourth sets of facets 162 and 164 magnify the optical aperture of the second image projector POD2 in opposite directions along the X-axis in the same manner as described above, directing the image illumination toward the externally coupled set of partial reflective surfaces 181 of the second portion 18 of LOE 12. As described above with reference to Figure 14B, the two portions of image illumination provided by the first and second image projectors combine at the EMB, preferably with slight overlap, to provide the user with a fully combined FOV.

[0074] When dual facets are used to enlarge the aperture of a single image projector, the configuration may be symmetrical or asymmetrical with respect to the positioning of the input aperture, the inclination of the facets, and other design considerations, as well as the length of the facets, and their reflectivity may vary along the sequence of facets, all as described above in the context of the implementation form of a single image projector.

[0075] An alternative set of implementations of this aspect of the present invention uses first and second optical magnification components located outside the LOE and optically coupled to the LOE. Examples of such implementations will now be described with reference to Figures 16A–16D and 19A–22C. In these non-limiting but preferred examples, the injection of image illumination from the first and second image projectors 210, 220 into the LOE 403 occurs via the first and second optical magnification components 203L and 203R, respectively.

[0076] As shown in Figures 16A to 16D, the first and second optical magnification components 203L and 203R may each be advantageously mounted on a slab having two main faces, one of which is optically coupled to an internal coupling surface associated with the LOE 403. In the present case, the two components are integrated into a single slab 203, thereby facilitating the manufacturing and assembly of the components. Optical coupling from slab 203 to LOE 403 may be achieved via a wedge prism 800 or other suitably formed coupling prism, providing an internal coupling surface angled obliquely to the main outer surface of the LOE 403. The oblique angle of the internal coupling surface is selected to allow direct internal coupling of image illumination within a range of angles propagating in the LOE 403 via internal reflections on the main outer surface. Direct optical coupling of the slab 203 and the inclined edge of the LOE 403 is also possible, as illustrated in Figure 19A below.

[0077] Figures 16A to 16D show the first and second optical magnification components 203L and 203R as parts of a planar slab 203 attached to a common planar internal bonding surface; however, in certain particularly preferred but non-limiting examples, separate internal bonding surfaces at different angles may be used. In such cases, as illustrated in Figure 19C, the slab of the first optical magnification component 203L is optically bonded to a first internal bonding surface 802L associated with LOE 403, and the slab of the second optical magnification component 203R is optically bonded to a second internal bonding surface 802R associated with LOE 403, with the first and second internal bonding surfaces 802L and 802R being non-coplanar. Using non-coplanar internal bonding surfaces may mitigate certain design considerations, particularly when seeking to achieve a wide field of view.

[0078] As an alternative to the edge coupling described above, other specific implementations of this aspect of the present invention utilize internal coupling of image illumination from the first and second optical magnification components 203L and 203R to the LOE403 via internal coupling surfaces, which are coplanar or parallel to one of the main outer surfaces of the LOE403. In this case, the LOE403 preferably includes at least one partially reflective internal coupling surface. Implementations of this approach are discussed herein with reference to Figures 20A to 22C.

[0079] Similar to the integrated implementation, the first and / or second optical magnification components 203L and 203R may also be implemented using two separate sets of partial reflective surfaces for optical aperture magnification per image projector, as illustrated in the examples in Figures 19A to 22C. An example of such an implementation is schematically shown in Figure 19A, where the first image projector POD1 injects image illumination through the first optical magnification component 203L, which includes both a first set of partial reflective surfaces 205 and a third set of mutually parallel partial reflective surfaces 207 that are non-parallel to the surface 205. The first and third sets of facets 205 and 207 magnify the optical aperture of the first image projector POD1 in opposite directions along the X-axis and direct the image illumination toward the internal coupling interface with waveguide 403 so that it propagates within LOE 403 by internal reflection until it is externally coupled toward EMB by external coupling facet 404.

[0080] Preferably, the second image projector POD2 also injects image illumination through a second optical expansion component 203R which includes both a second set of partial reflective surfaces 206 and a fourth set of mutually parallel partial reflective surfaces 208 that are non-parallel to surfaces 206. The second and fourth sets of facets 206 and 208 expand the optical aperture of the second image projector POD2 in opposite directions along the X-axis and direct the image illumination toward the internal coupling interface with waveguide 403 so that it propagates within LOE 403 by internal reflection until it is externally coupled toward EMB by external coupling facet 404. As described above with reference to Figure 14B, the two portions of image illumination provided by the first and second image projectors combine at EMB, preferably with slight overlap, to provide the user with a fully combined FOV.

[0081] When dual facets are used to enlarge the aperture of a single image projector, the configuration may be symmetrical or asymmetrical with respect to the positioning of the input aperture, the inclination of the facets, and other design considerations, as well as the length of the facets, and their reflectivity may vary along the sequence of facets, all as described above in the context of the single image projector implementation. An example of the first, and in this case the second, asymmetric facet inclination with respect to the central optical axis of the image projector is shown in Figures 21A and 21B. This allows for optimization of the facet angles of the corresponding portions of the field of view related to the illumination of the EMB.

[0082] Referring to Figure 17, an exemplary implementation of a system of optical magnification 201 is shown, which includes two optical aperture magnification components 203L and 203R integrated into a single slab element 203 for magnifying the optical apertures of two image projectors 210, 220 (not shown in this figure) for injection into the LOE. The optical aperture magnification components magnify the effective apertures of the two image projectors, which are then injected into the LOE for display to the user. The current figure is viewed from the edge of the optical aperture magnification components. The aperture magnification structure may be symmetrical and may include mirrors on the sides, or more generally, outside the field of view.

[0083] Figure 17 shows non-limiting details of possible implementations of the image projector suitable for use in any and all of the dual POD implementation configurations described herein. In the non-limiting examples shown herein, a common light source, e.g., an LED light source 202, is provided as part of an exemplary light source configuration 200 to illuminate both image projectors, the two “PODs” (microdisplay projectors), the left POD 210 and the right POD 220. Note that the use of “left” and “right” throughout this description is for ease and clarity of reference and does not restrict direction or position, etc. Each POD typically provides about half of the original image (original images are not shown), providing the left collimated image 204CL and the right collimated image 204CR to their respective aperture-enlarging components 203L and 203R. Two collimated images 204C propagate along the x-axis, are magnified by the aperture expansion component, and projected from the aperture expansion component onto LOE 403, represented as the principal rays, left externally coupled ray 238L and right externally coupled ray 238R. As shown in other figures, the left and right externally coupled rays (238L, 238R) traverse LOE 403 and are externally coupled from a single LOE 403 as externally coupled rays (left externally coupled ray 38L and right externally coupled ray 38R) in the direction of the user (user's eye) at the externally coupled partial reflecting surface 404 along the z-axis.

[0084] An exemplary light source 200 typically includes light 202 provided by one or more LEDs or other light sources known in the art, which is typically rapidly switchable between red, green, and blue illumination, illuminating together a sequence of color image separations that constitute a single “frame” of the projected image. The light 202 is typically expanded by an expander 205 and then split into two beams (shown as a dotted line on the left and a dashed line on the right) by, for example, a polarizing selective reflector (PBS) 206, which propagate to the left POD 210 and the right POD 220 via corresponding optical pipes (left optical pipe 207L and right optical pipe 207R), respectively.

[0085] Each of the exemplary PODs (left POD 210 and right POD 220) receives respective beams of light (left beam and right beam) crossing the POD via PBS (left PBS 214, right PBS 224) and collides with display devices (left display device 212 and right display device 222). Images can be acquired from each of the display devices (212, 222) either directly from a spatial light modulator (SLM) such as a cathode ray tube (CRT), liquid crystal display (LCD), liquid crystal on silicon (LCoS), digital micromirror device (DMD), OLED display, scanning source or similar device, or indirectly using a relay lens or fiber optic bundle. As described below with reference to Figure 14B, the image from each display device (212, 222) is typically about half of the entire displayed image. Each half of the image is propagated via PBS (left PBS214, left PBS216 and right PBS224, right PBS226) through the PODS (210, 220), collimated by the collimators (left collimator 218 and right collimator 228), and output from the POD (210, 220) as collimated images (left collimated image 204CL and right collimated image 204CR) to the respective aperture expansion components 203L and 203R.

[0086] The illustrative description of light sources 200 and PODs (210, 220) is non-limiting. Based on this description, those skilled in the art will be able to implement other light sources and image sources. For example, each POD may use different sections of a single LCOS, and each POD may have separate individual LEDs.

[0087] Each of the aperture-expanding components 203L and 203R includes a first region (left first region 54L and right first region 54R) to which the respective collimated images (left collimated image 204CL and right collimated image 204CR) are coupled to the substrate. Each of the aperture-expanding components includes a respective waveguide (left waveguide 20L and right waveguide 20R), also called the "planar substrate" and the "light-transmitting substrate." Each of the waveguides (20L, 20R) includes at least two (primary) surfaces that are parallel to each other, shown in the current figure as the lower (primary) surface 26 and the upper (primary) surface 26A. Each of the waveguides (20L, 20R) includes a respective set of facets (left facet 22L and right facet 22R), shown as a double line between the two first surfaces (26, 26A). Each set of facets (22L, 22R) includes the first facet (left first facet 40AL, right first facet 40AR) on the side of the facet closest to the first region (54L, 54R) where the collimated image (204CL, 204CR) is coupled to the substrate (20L, 20R). Similarly, each set of facets (22L, 22R) includes the last facet (left last facet 40BL, right last facet 40BR) on the distal side of the facet from the first region (54L, 54R). As the collimated light (204CL, 204CR) propagates along the sides (203L, 203R) of the respective aperture expander components, the captured propagating light is progressively externally coupled from the aperture expander 203 by the partially reflective surfaces of the facets (22R and 22L) as the left externally coupled ray 238L and the right externally coupled ray 238R. The area over which the rays are externally coupled from the sides of the aperture expander components (203L, 203R) into a single LOE 403 is indicated as the respective field of view (FOV) (left field of view FOV-L and right field of view FOV-R). The above configuration of the aperture expander components allows for the use of highly reflective surfaces or mirrors at specific locations, since these surfaces are not in the user's FOV. For example, the first facets (40AL, 40AR) and the last facets (40BL, 40BR) can be 100% reflective.

[0088] Using two separate PODs to inject different portions of the overall field of view can offer any of many advantages, including, but not limited to, achieving an enlarged field of view and reducing the size and weight of the PODs compared to what would be required with a single POD providing the entire image.

[0089] Each POD projects approximately half of the image beam. For example, in a 55.5° FOV system with an aspect ratio of 16 / 9, a single POD typically projects a beam of 48.44° horizontally and 27.22° vertically.

[0090] As explained, dividing the FOV horizontally using an aperture expansion component results in two PODs, each handling a 24.22° x 27.22° FOV. As mentioned above, some overlap between the two PODs is desirable. If each POD overlaps by 3°, each POD projects 27.22° x 27.22°, with 3° overlap. The image (photograph) can be divided into two display devices (212, 222) in each of the two PODs (210, 220) using some of the information common to the two PODs. The concept of dividing into two PODs can be better understood by referring to Figures 16A-16D, which include simulated ray traces. Each POD is assumed to have its own SLM (LCOS in this example) and may have its own lighting system or a shared lighting system.

[0091] Figures 16B, 16C, 16D, and 16E correspond to the views along lines V1, V2, V3, and V4, respectively, as shown in Figure 16A.

[0092] Referring to Figure 16C, a sketch of the system 201 from the apex angle is shown, with a single LOE 403 partially visible (at a certain angle) below the aperture expander 203. The left POD 210 is shown to provide the left collimated image 204CL to the aperture expanding component 203L, and the rays of the left collimated image 204CL are shown as the left first edge 410L and the left second edge 412L of the image. The rays of the left first and second edges (410L, 412L) propagate through the aperture expanding component 203L and are shown externally coupled to the single LOE 403 as the left externally coupled ray 238L, in which the left externally coupled ray 38L is then externally coupled toward the EMB.

[0093] Similarly, the right POD 220 is shown to provide the right collimated image 204CR to the aperture expansion component 203R, and the rays of the right collimated image 204CR are shown as the first right edge 410R and the second right edge 412R of the image. The rays of the first and second right edges (410R, 412R) propagate through the aperture expansion component 203R and are shown externally coupled to a single LOE 403 as the right externally coupled ray 238R, in which the right externally coupled ray 38RL is then externally coupled toward the EMB.

[0094] The propagating light rays are integrated into a single LOE403 at the position of the human eye (EMB), indicated by a square detector.

[0095] Referring to Figure 16E, a sketch of the system 201 viewed from the front is shown, with a single LOE 403 visible below the aperture expander 203. Since the z-axis is “off-page,” the external coupling rays (left external coupling ray 38L and right external coupling ray 38R) are “off-page” towards the user’s eye 10 and are not shown in this figure.

[0096] Referring to Figure 16D, a sketch of the system 201 viewed from above is shown, with a single LOE 403 not visible (below the aperture expander 203). The external coupling rays (left external coupling ray 38L and right external coupling ray 38R) are directed towards the EMB and the user's eye 10, along the z-axis (downward as shown). In this figure, the additional beams, the left third beam 414L and the right third beam 414R, are shown, indicating the left and right edges of the field of view near the centerline of the image height.

[0097] Referring to Figure 16A, a sketch of system 201 is shown from the left side, viewed from the side, propagating along the y and z axes. From this figure, it is clear that the illustrated beams 410L and 412L correspond to the lowest and highest edges of the field of view in the image, but are horizontally centered in the field of view (as is clear from Figures 16B and 16C). The wedge 800 is used to connect the aperture expander 203 to a single LOE 403. The wedge 800 is a non-limiting example of one type of connection that can be used between the aperture expander 203 and a single LOE 403. Depending on the specific requirements of the implementation form, other devices and configurations can be used to provide the desired angle and connection.

[0098] Referring to Figure 16B, a sketch of system 201 is shown, viewed from above at a 45-degree angle to the plane of a single LOE (y-axis). A single LOE 403 is visible below the aperture expander 203. Since the z-axis is "off-page", the external coupling rays (left external coupling ray 38L and right external coupling ray 38R) are "off-page" towards the user's eye 10, and their location is shown in the figure.

[0099] Referring here to Figures 20A–22C, these illustrate an alternative internal coupling configuration in which the aperture expansion component is optically associated with an internal coupling surface that is coplanar or parallel to one of the main outer surfaces of the LOE403. In this case, at least one internal reflective surface within the LOE403 is used for internal coupling of the image illumination so that it propagates within the LOE403 by internal reflection. According to certain particularly preferred implementations, internal coupling is achieved using a set of mutually parallel partial reflective internal coupling surfaces. Figures 20A–20C illustrate an implementation using this approach, which uses a single set of partial reflective surfaces for each aperture expansion component, while Figures 21A–21C illustrate an aperture expansion component that uses two sets of partial reflective surfaces per image projector, where the facets are asymmetrically tilted with respect to the main plane of the device. Figures 22A–22C illustrate an optical system using the aperture expansion components of Figures 21A–21C. Using asymmetrical tilting of facets may improve the system's performance and compactness. As seen in this system, the displayed field of view (FOV) of light is very large, but the pods required to fill the entire EMB (Earth Microscope) are relatively small.

[0100] In this example, and throughout this document, it should be noted that each set of partially reflective inner surfaces ("facets") may have uniform or non-uniform spacing and may extend across the entire thickness dimension of the opening enlargement component (between the two main parallel outer surfaces) or only over a portion of that thickness dimension.

[0101] All of the above principles can also be applied to a "landscape" configuration, in which case the image is injected from a POD located laterally outside the display area to combine with the user's eye, and then diffused vertically by a first set of facets and then horizontally by a second set of facets. It should be understood that all of the above configurations and variations are also applicable to side-note configurations.

[0102] Throughout the above description, the X and Y axes are referred to as shown, where the X axis is horizontal or vertical and corresponds to one dimension of optical aperture magnification, and the Y axis is another principal axis corresponding to a second dimension of magnification. In this context, X and Y may be defined with respect to the orientation of the device when worn on the user's head, as typically defined by the support configuration such as the aforementioned eyeglass frames in Figures 1A and 1B. Other terms that typically coincide with its definition of the X axis include (a) at least one straight line that demarcates the eye movement box which can be used to define a direction parallel to the X axis, (b) the edges of the rectangular projected image are typically parallel to the X and Y axes, and (c) the boundary between the first region 16 and the second region 18 typically extends parallel to the X axis.

[0103] The above description is intended to serve as an example only, and it will be understood that many other embodiments are possible within the scope of the invention as defined in the attached claims.

Claims

1. An optical system for directing image illumination injected into at least one internal coupling region to an eye movement box for viewing by the user's eye, comprising a light guide optical element (LOE) formed from a transparent material, the LOE is (a) A first region comprising a first set of mutually parallel partial reflecting surfaces of a plane having a first orientation, (b) The first region further includes a second set of mutually parallel partial reflecting surfaces of a plane having a second orientation nonparallel to the first orientation, (c) A second region comprising a third set of mutually parallel partial reflecting surfaces of a plane, each having a third orientation that is not parallel to the first orientation and the second orientation, (d) A set of mutually parallel main outer surfaces, the set of mutually parallel main outer surfaces extending across the first and second regions such that the first set of partial reflective surfaces, the second set of partial reflective surfaces, and the third set of partial reflective surfaces are all located between the main outer surfaces, An optical system in which a third set of partial reflective surfaces is at an oblique angle to the main outer surface such that a portion of the image illumination propagating within the LOE due to internal reflection from the main outer surface from the first region to the second region is externally coupled toward the eye movement box from the LOE, and each of the first and second sets of partial reflective surfaces is oriented such that a portion of the image illumination propagating within the LOE due to internal reflection from the main outer surface from at least one internal coupling region is deflected toward the second region.

2. The optical system according to claim 1, wherein a first set of partial reflective surfaces deflects a first portion of the field of view of the image toward a second region, and a second set of partial reflective surfaces deflects a second portion of the field of view of the image toward a second region, so that the first and second portions of the field of view combine to provide a continuous combined field of view that is larger than each of the first and second portions.

3. The optical system according to claim 1, wherein each of the first and second sets of partial reflectors includes a deflection surface configured to reflect most of the image illumination incident on the deflection surface, and the deflection surface is deployed to become the first partial reflector of each of the first and second sets of partial reflectors reached by the image illumination injected into the at least one internal coupling region.

4. The optical system according to claim 3, wherein the deflection surface of the first set of partial reflective surfaces and the deflection surface of the second set of partial reflective surfaces intersect in a straight line.

5. The optical system according to claim 3, wherein each of the first and second sets of partial reflective surfaces includes a filler surface adjacent to the deflection surface, the filler surface having a length measured parallel to the main outer surface that is shorter than the length of the deflection surface and shorter than the length of another partial reflective surface adjacent to the filler surface.

6. The optical system according to claim 1, wherein the first and second sets of partial reflective surfaces each have non-uniform spacing between them.

7. The optical system according to claim 1, wherein each of the first and second sets of partial reflective surfaces has a length measured parallel to the main outer surface, and each of the first and second sets of partial reflective surfaces includes partial reflective surfaces having different lengths.

8. The optical system according to claim 1, wherein the internal coupling region is located in the middle third of the dimensions of the LOE.

9. The optical system according to claim 1, wherein at least one edge of the LOE adjacent to the first region of the LOE is mounted as a mirror surface perpendicular to the main outer surface, and the path of the image illumination from the internal bonding region of the LOE to the second region includes at least one reflection from the mirror surface of the at least one edge of the LOE.

10. The optical system according to claim 1, further comprising an image projector configured to project image illumination corresponding to a collimated image, wherein the image projector is optically coupled to the LOE in an internal coupling region to inject the image illumination into a first region of the LOE such that it propagates within the LOE by internal reflections on the main outer surface, and the image illumination is injected with an effective optical aperture and an effective propagation direction such that it is incident on both the first set of partial reflective surfaces and the second set of partial reflective surfaces.

11. The optical system according to claim 10, wherein the dimensions of the first set of partial reflectors perpendicular to the effective propagation direction are greater than the dimensions of the second set of partial reflectors perpendicular to the effective propagation direction.

12. The optical system according to claim 10, wherein the angle formed between the partial reflective surfaces of the first set of partial reflective surfaces and the effective propagation direction is smaller than the angle formed between the partial reflective surfaces of the second set of partial reflective surfaces and the effective propagation direction.

13. The optical system according to claim 1, further comprising a first image projector configured to project image illumination corresponding to a first portion of a collimated image, wherein the first image projector is optically coupled to the LOE in a first internal coupling region to inject the image illumination into a first region of the LOE such that it propagates within the LOE by internal reflection of the main outer surface and incident on a first set of partial reflective surfaces, and the first and second portions of the collimated image are combined in the eye movement box to provide a combined image.

14. The optical system according to claim 1, wherein the first and second sets of partial reflective surfaces are perpendicular to the main outer surface of the LOE.

15. The optical system according to claim 1, wherein the first and second sets of partial reflective surfaces are oblique to the main outer surface of the LOE.

16. An optical system for delivering images to an eye movement box for viewing by the user's eyes, (a) A light guide optical element (LOE) formed from a transparent material, comprising an external coupling set of mutually parallel planar partial reflective surfaces and a set of mutually parallel main outer surfaces, wherein the external coupling set of partial reflective surfaces is located between the main outer surfaces of the LOE, (b) A first image projector configured to project image illumination corresponding to a first portion of a collimated image from an optical aperture, the first image projector following a first optical path from the optical aperture to the LOE such that the image illumination propagates within the LOE by internal reflection of the main outer surface and is progressively externally coupled from the LOE toward the eye movement box by an external coupling set of the partial reflective surfaces, (c) A second image projector configured to project image illumination corresponding to a second portion of a collimated image from an optical aperture, the second image projector following a second optical path from the optical aperture to the LOE such that the image illumination propagates within the LOE by internal reflection of the main outer surface and is progressively externally coupled from the LOE toward the eye movement box by an external coupling set of partial reflective surfaces, the first and second portions of the collimated image being combined in the eye movement box to provide a combined image, (d) A first optical magnification component comprising a first set of mutually parallel partial reflective surfaces having a first orientation, the first optical magnification component being deployed in the first optical path to magnify the optical aperture of the first image projector and direct the image light toward the external coupling set of the partial reflective surfaces, (e) an optical system comprising a second optical magnification component including a second set of mutually parallel partial reflective surfaces having a second orientation, the second optical magnification component being deployed in the second optical path to magnify the optical aperture of the second image projector and direct the image light toward the externally coupled set of partial reflective surfaces.

17. The optical system according to claim 16, wherein the first optical magnification component and the second optical magnification component are external components optically coupled to the LOE, and the injection of the image illumination from the first and second image projectors into the LOE occurs via the first and second optical magnification components, respectively.

18. The optical system according to claim 17, wherein each of the first and second optical magnification components is mounted on a slab having two main surfaces, and one of the main surfaces is optically coupled to an internal coupling surface associated with the LOE.

19. The optical system according to claim 18, wherein the internal bonding surface is angled obliquely with respect to the main outer surface of the LOE.

20. The optical system according to claim 18, wherein the slab of the first optical magnification component is optically coupled to a first internal bonding surface associated with the LOE, the slab of the second optical magnification component is optically coupled to a second internal bonding surface associated with the LOE, and the first and second internal bonding surfaces are not coplanar.

21. The optical system according to claim 18, wherein the internal bonding surface is coplanar or parallel to one of the main outer surfaces of the LOE, and the LOE includes at least one partially reflective internal bonding surface.

22. The optical system according to claim 16, wherein the first set of partial reflective surfaces and the second set of partial reflective surfaces are located within the LOE, between the main outer surfaces of the LOE.

23. The optical system according to claim 22, wherein the first and second sets of partial reflective surfaces are perpendicular to the main outer surface of the LOE.

24. The optical system according to claim 22, wherein the first and second sets of partial reflective surfaces are oblique to the main outer surface of the LOE.

25. The optical system according to claim 16, wherein the first optical magnification component further includes a third set of parallel partial reflective surfaces that are non-parallel to the first set of partial reflective surfaces, the first and third sets of partial reflective surfaces magnify the first optical aperture of the first image projector in opposite directions and direct the image light toward the externally coupled set of partial reflective surfaces.

26. The optical system according to claim 25, wherein the first image projector has a central optical axis, and the third set of partial reflective surfaces has an inclination with respect to the central optical axis that is different from the inclination of the first set of partial reflective surfaces with respect to the central axis.

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