Optical aperture expansion arrangement for near-eye displays

Abstract

The present disclosure relates to optical aperture expansion arrangements for near-eye displays. An optical aperture expansion arrangement particularly useful for near-eye displays employs a waveguide (30, 140, 145) with a wedge-like configuration (25, 26) to generate two modes of propagation of image illumination along the waveguide and to couple the two modes out of the waveguide. Various embodiments employ a rectangular waveguide in which image illumination propagates by four-fold internal reflection. In some cases, the wedge-like configuration is combined with an array of partially-reflecting internal surfaces (45, 150) to achieve two-dimensional aperture expansion.

Description

[0001] This application is a divisional application of the invention patent application filed on November 21, 2018, with application number "201880074821.6" and invention title "Optical Aperture Expansion Arrangement for Near-Eye Display". Technical Field

[0002] This invention relates to near-eye displays, and more particularly, to optical aperture expansion arrangements for near-eye displays. Background Technology

[0003] Some near-eye displays are based on waveguides that expand the aperture of a small projector to a larger aperture to display to the observer's eye. The waveguide includes an output coupling mechanism to deliver light from the waveguide to the eye.

[0004] Aperture expansion is typically subdivided into two stages, extending sequentially along two dimensions. The second dimension, which provides the output to the eye, can be based on a waveguide containing internal facets, commercially available from Lumus Ltd. (Israel), or it can employ a waveguide containing diffractive optics for coupling out the image.

[0005] Various arrangements can be used to provide aperture expansion in the first dimension. An example is described in PCT Patent Publication WO 2017 / 141242 (hereinafter referred to as "'242 Publication"), in which coupling in and coupling out are achieved by a wedge-shaped construction at the end of the waveguide (which forms a parallelogram structure when viewed from the side). Summary of the Invention

[0006] The present invention is an optical device that provides aperture expansion that is particularly useful in near-eye displays.

[0007] According to the teachings of embodiments of the present invention, an optical device is provided, comprising: a first optical waveguide having an elongation direction, the first optical waveguide having a first pair of parallel surfaces and a second pair of parallel surfaces, the first pair of parallel surfaces and the second pair of parallel surfaces being parallel to the elongation direction, forming a rectangular cross section for guiding light through quadruple internal reflection at the first pair of parallel surfaces and the second pair of parallel surfaces, each ray undergoing internal reflection thereby defining a set of four conjugate propagation directions, at least a portion of the first optical waveguide being delimited by a first wedge-shaped surface and a second wedge-shaped surface, the first wedge-shaped surface being configured such that it is connected to the first optical waveguide. At least a portion of the light corresponding to the injected image propagating along a first direction in a first set of conjugate propagation directions is deflected by reflection at a first wedge-shaped surface to propagate along a second direction in a second set of conjugate propagation directions. The second direction has a smaller angle with the elongation direction compared to the first direction. The second wedge-shaped surface is parallel to the first wedge-shaped surface to deflect the image propagating along at least one direction in the second set of conjugate directions to propagate along at least one direction in the first set of conjugate directions, and to couple the image propagating along one of the directions in the first set of conjugate directions out of the first optical waveguide.

[0008] According to another feature of an embodiment of the present invention, the first wedge-shaped surface is the outer surface of the first optical waveguide.

[0009] According to another feature of an embodiment of the invention, the first wedge-shaped surface is coated with a reflective coating.

[0010] Another feature of an embodiment of the invention is that the first wedge-shaped surface is coated with a partially reflective coating.

[0011] According to another feature of an embodiment of the invention, the first wedge-shaped surface is translucent, and wherein at least the portion of the parallel surface facing the first wedge-shaped surface is coated with a reflective coating.

[0012] According to another feature of an embodiment of the invention, the injected image introduced into the first optical waveguide is deflected from the injection direction to a direction in the first set of conjugate directions by a first reflection from the first wedge-shaped surface, and after additional reflection from at least one of the parallel planes, is further deflected from a direction in the first set of conjugate directions to a direction in the second set of conjugate directions by a second reflection from the first wedge-shaped surface.

[0013] According to another feature of an embodiment of the present invention, a coupling prism is also provided adjacent to or adjacent to the coupling region of the first waveguide, the coupling prism including at least one surface extending from the corresponding surface of the first waveguide.

[0014] According to another feature of an embodiment of the invention, a light guide having two principal parallel surfaces is also provided, wherein a first waveguide is deployed such that an image coupled out from the first waveguide is coupled into the light guide to propagate within the light guide by internal reflection at the two principal parallel surfaces, the light guide further including a coupling arrangement for coupling out the image propagating within the light guide to direct the image toward the user's eye.

[0015] According to another feature of an embodiment of the invention, a second optical waveguide is further provided, having a first pair of parallel surfaces and a second pair of parallel surfaces parallel to the elongation direction, forming a rectangular cross-section for guiding light through quadruple internal reflection at the first pair of parallel surfaces and the second pair of parallel surfaces. At least a portion of the second optical waveguide is delimited by a first wedge-shaped surface and a second wedge-shaped surface. The first and second optical waveguides are deployed in a stacked relationship and configured such that a projected image having a first aperture size is partially coupled into each of the first and second optical waveguides, and such that the second wedge-shaped surface of the first and second optical waveguides each serves as part of a coupling structure, the coupling structure being deployed to provide an effective output aperture having a size larger than the first aperture size.

[0016] According to another feature of an embodiment of the invention, for each of the first and second optical waveguides, a portion of one of the first wedge-shaped surface and the parallel surface that faces the first wedge-shaped surface forms a coupling configuration, and the optical device further includes a filling prism that substantially fills the wedge-shaped gap between the coupling configurations.

[0017] According to another feature of an embodiment of the invention, the first wedge-shaped surface of the second optical waveguide is coated to be partially reflective, thereby coupling a portion of the projected image in and allowing a portion of the projected image to reach the first coupling configuration.

[0018] According to another feature of an embodiment of the invention, a portion of one of the parallel surfaces that faces the first wedge-shaped surface of the first optical waveguide is coated to be partially reflective, thereby coupling a portion of the projected image in and allowing a portion of the projected image to reach the second coupling configuration.

[0019] According to another feature of an embodiment of the invention, the first optical waveguide and the second optical waveguide are part of a stack of at least three optical waveguides.

[0020] According to another feature of an embodiment of the invention, the image coupled from the second optical waveguide propagates through the first optical waveguide.

[0021] According to another feature of an embodiment of the invention, the first wedge-shaped surface and the second wedge-shaped surface of the first optical waveguide are inclined at an angle relative to the first pair of parallel surfaces and perpendicular to the second pair of parallel surfaces.

[0022] According to another feature of an embodiment of the invention, the first wedge-shaped surface and the second wedge-shaped surface of the first optical waveguide are inclined at an oblique angle relative to both the first pair of parallel surfaces and the second pair of parallel surfaces.

[0023] According to the teachings of embodiments of the present invention, an optical device is also provided, comprising: a first optical waveguide having at least a first pair of parallel surfaces for guiding light by internal reflection, the first optical waveguide including a plurality of mutually parallel partially reflective surfaces oriented not parallel to the paired parallel surfaces; a wedge-shaped configuration formed between a first wedge-shaped surface and one of the parallel surfaces, the wedge-shaped configuration being configured such that light corresponding to at least a portion of an injected image propagating in a first direction within the first optical waveguide is deflected by reflection at the first wedge-shaped surface to propagate in a second direction, the second direction having a smaller angle with the elongation direction of the first optical waveguide compared to the first direction. The light rays in the first and second directions are deflected at the partially reflective surface to a first deflection direction and a second deflection direction, respectively, to be coupled out from the first optical waveguide; the second optical waveguide has a second pair of parallel surfaces for guiding light by internal reflection, the second optical waveguide is deployed to receive portions of the injected image propagating along the first and second deflection directions, the second optical waveguide includes a coupling wedge structure formed between the second wedge-shaped surface and one of the second pair of parallel surfaces, the coupling wedge structure is deployed to couple out at least portions of the image propagating along the first deflection direction by a single reflection from the wedge-shaped surface and propagating along the second deflection direction by being reflected twice from the wedge-shaped surface. Attached Figure Description

[0024] In this document, the invention is described by way of example only with reference to the accompanying drawings, in which:

[0025] Figure 1A This is a schematic front view of an optical device including a waveguide constructed and operated according to an embodiment of the present invention;

[0026] Figure 1B Is with Figure 1A A schematic front view of an optical device with an alternative configuration for coupling a projected image, similar to the optical device in the example;

[0027] Figure 1C Through Figure 1A A schematic cross-sectional view of the waveguide in the image is shown twice to illustrate two different modes of image propagation.

[0028] Figure 2A Is adopted Figure 1B Front view of the optical device of the first waveguide and the second waveguide;

[0029] Figure 2B It is along Figure 2A A sectional view taken from line A in the diagram;

[0030] Figure 3A Is adopted with Figure 1A Front view of an optical device with similar waveguide stacking;

[0031] Figure 3B It is along Figure 3A A sectional view taken from line A in the diagram;

[0032] Figure 4 Is with Figure 3A Similarly, it shows the same as Figure 1B A similar alternative coupling construction's front view;

[0033] Figure 5A and Figure 5B This is a schematic isometric view of a waveguide with a coupling prism according to the teachings of the present invention, wherein the waveguide employs two sets of parallel surfaces and wedge-shaped surfaces that are inclined at an oblique angle to only one set of parallel surfaces.

[0034] Figures 6A to 6C These are schematic top, side, and front views of an apparatus for realizing two-dimensional optical aperture expansion according to another aspect of the present invention.

[0035] Figure 7A and Figure 7B They are Figures 6A to 6C The schematic side and front views of the device in the diagram show a modified implementation using an alternative coupling geometry; and

[0036] Figures 8A to 8C They are respectively with 6A to Figure 6C The diagram shows a schematic top view, side view, and front view of a device similar to the one shown, implemented using two plate waveguides. Detailed Implementation

[0037] The present invention is an optical device that provides aperture expansion, which is particularly useful in near-eye displays.

[0038] The principles and operation of the optical device according to the present invention can be better understood by referring to the accompanying drawings and description.

[0039] Now refer to the attached diagram, Figures 1A to 5B Various implementations of an optical device that provides aperture expansion, particularly useful in near-eye displays, are shown, comprising a first subset of the construction and operation according to a non-limiting embodiment of the invention.

[0040] In general, the optical device includes a first optical waveguide 30 having an elongation direction D. The optical waveguide 30 has a first pair of parallel planes 12a, 12b and a second pair of parallel planes 14a, 14b parallel to the elongation direction D. These parallel planes form a rectangular cross-section for guiding light through quadruple internal reflection at the first pair of parallel planes 12a, 12b and the second pair of parallel planes 14a, 14b. In this context, "rectangular" includes the special case of a square cross-section. As a result of this quadruple internal reflection, each ray undergoing internal reflection thus defines a set of four conjugate propagation directions, which, for example, in… Figure 1C The light rays are represented as a1, a2, a3, and a4.

[0041] According to one aspect of the invention, at least a portion of the optical waveguide 30 is defined by a first wedge-shaped surface 21 and a second wedge-shaped surface 22, which together with adjacent regions of one or more parallel surfaces form corresponding wedge-shaped structures 25 and 26, respectively.

[0042] The first wedge-shaped surface 21 is preferably configured such that light rays a3, a4 corresponding to at least a portion of an injected image propagating along at least a portion of a first direction a3 or a4 of a first set of conjugate propagation directions a1 to a4 within the first optical waveguide are deflected by reflection at the first wedge-shaped surface 21 to propagate along a second direction c1 or c2 of a second set of conjugate propagation directions c1 to c4, where the angle between the second direction and the elongation direction is smaller than that of the first direction. In other words, after the image has been coupled into the waveguide 30 along the first set of conjugate directions a1 to a4, further reflection at the wedge-shaped surface 21 deflects the image propagation direction to another set of conjugate directions c1 to c4, which strike the parallel surface at a shallower angle of incidence. The image itself propagating along the first set of conjugate directions a1 to a4 can be coupled in via the first reflection from the wedge-shaped surface 21, such as... Figure 1A and Figure 1B As shown. Therefore, in Figures 1A to 1C In the example, the light rays of the input projected image enter the first wedge-shaped structure 25 via one of the parallel surfaces 12a, and are then reflected once from the wedge-shaped surface 21 to generate a first deflected ray corresponding to ray a1 or a2 (which interchanges with each other via reflections at sides 14a and 14b). These rays are reflected at surface 12a to form conjugate rays a3 and a4. For the portion of the aperture indicated by the solid arrow, the next boundary reached by rays a3 and a4 is surface 12b beyond the end of the wedge-shaped surface. Thus, this portion of the projected image propagates via quadruple internal reflection as it travels along the waveguide, where quadruple internal reflections are as follows: Figure 1C(Left) As shown, rays a1 to a4 are interchanged. For another portion of this aperture, rays a3 and a4 again fall on the wedge-shaped surface 21, causing further deflection to generate rays c1 and / or c2, and passing through as... Figure 1C (Right) shows the quadruple internal reflection of conjugate rays c1 to c4 propagating along the waveguide. Compared to rays a1 to a4, rays c1 to c4 form smaller angles with the waveguide's extension direction D, but this difference is... Figure 1C It is not visible in the axial view.

[0043] Incidentally, whether the image is referred to herein as a beam or a ray, it should be noted that a beam is a sample bundle of the image, which is typically formed by multiple beams at slightly different angles, each corresponding to a point or pixel in the image. Except in cases specifically referred to as the extremity of the image, the bundles shown are generally the centroid of the image. Furthermore, illumination for each pixel is not limited to a specific ray location, but is preferably a wide, parallel ray beam that essentially “fills” the corresponding dimension of the waveguide. Therefore, the sample rays shown herein are typically part of a wider, continuous ray spanning the output aperture of the image projection device.

[0044] The tilt angle between the wedge-shaped surface 21 and the surface 12a is preferably chosen to satisfy several geometric requirements. First, for the entire field of view of the image, taking into account the expected injection direction of the projected image, the wedge angle is chosen such that the first reflected rays a1, a2 undergo internal reflection at the parallel plane of the waveguide. Furthermore, the wedge angle is chosen to be shallow enough that the aforementioned repeated reflections from the wedge-shaped surface for generating rays c1, c2 can occur, while ensuring that the field of view of the image in the first and second deflected images does not overlap in angular space. An example of how these conditions are numerically evaluated in the case of double reflection is presented in the aforementioned '242 disclosure, and as will be apparent to those skilled in the art, the example can be readily adapted to the case of quadruple reflection in this invention. The invention is not limited to two propagation modes, and a third propagation and its conjugate can also be used, particularly when only a relatively small angular field of view is required, wherein the third propagation and its conjugate are achieved after one of the rays c1 to c4 is further reflected at the wedge-shaped surface.

[0045] In this configuration, the second wedge-shaped surface 22 is parallel to the first wedge-shaped surface 21, thereby forming a second wedge-shaped structure 26. This structure couples out the image illumination propagating within the waveguide in a manner similar to the coupling described above. Specifically, the second wedge-shaped surface 22 deflects the image propagating along at least one of the second set of conjugate directions c1 to c4 so that the image propagates along at least one of the first set of conjugate directions a1 to a4, and further couples out the image propagating along one of the first set of conjugate directions a1 to a4 so that the image leaves the optical waveguide 30.

[0046] Figure 1A The construction, in the side view, appears similar to that described in the aforementioned '242 disclosure. However, the '242 disclosure involves a waveguide where reflection occurs only at a pair of parallel surfaces (i.e., double reflection), and the other dimension of this waveguide (as shown in the page) is relatively large to avoid light rays crossing the other ends of the waveguide. In contrast, certain preferred embodiments of the invention employ a rectangular waveguide approach, thereby providing guidance of image illumination in two dimensions through quadruple internal reflection, and thus allowing the use of optical elements that are much more compact than those that can be used with plate waveguide methods.

[0047] Although wedge-shaped surfaces 21 and 22 are shown here at an angle to a pair of parallel surfaces 12a, 12b and perpendicular to another pair of parallel surfaces 14a, 14b, the rectangular waveguide method also allows for the use of wedge-shaped surfaces inclined at an angle relative to the two pairs of parallel surfaces. References will follow. Figure 5A An example of this is shown. In general, as long as the wedge geometry is similar to the first wedge construction and the second wedge construction, the decoupling geometry still effectively “undoes” the effect of the incoupling geometry.

[0048] exist Figure 1A In its construction, depending on the injection angle of the projected image and the angle of the wedge itself, the wedge-shaped surface 21 can achieve sufficient internal reflection in some cases without the need for a coating. However, in most cases, it is preferable to provide a reflective coating to the wedge-shaped surface 21, or, in some cases discussed further below, a partially reflective coating. The second wedge-shaped surface 22 is preferably provided with a reflective coating. This reflective coating (indicated herein by bold lines) can be implemented using metallic or dielectric coatings as known in the art.

[0049] Figure 1BAlternative coupling geometries are shown, which in some implementations may facilitate a more compact overall product form factor. In this case, the first wedge-shaped surface 21 is the light-transmitting outer surface of the optical waveguide 30 and the surface through which the injected image is guided. At least the portion of face 12a facing the first wedge-shaped surface 21 is coated with a (fully or partially) reflective coating 27, thereby reflecting all or part of the injected image back to the wedge-shaped surface 21, where light undergoes reflection equivalent to... Figure 1A The first reflection in the structure. The remaining reflections are similar to the above combination. Figure 1A The reflection described.

[0050] Figure 1B The coupling configuration, including a variation employing a larger waveguide in another dimension to accommodate the entire field of view of the image using only double reflections in waveguide 30 (i.e., otherwise similar to the configuration described in the above '242 publication), is considered advantageous in a wide range of applications.

[0051] Figures 2A to 2B An implementation of a near-eye display is illustrated, wherein an image is transmitted using a waveguide 30 to a second waveguide (or “light guide”) 20 having two principal parallel surfaces 24a, 24b, from which the image is coupled toward the observer’s eye 47 (propagating in the form of light rays b1 and b2). In a particularly preferred but non-limiting example shown here, the second waveguide employs a plurality of mutually parallel, angled, internally partially reflective surfaces 45 for coupling the image toward the eye. The light guide 20 having internally partially reflective surfaces 45 can be readily implemented using design and manufacturing techniques known in the art, wherein similar elements are commercially available from a range of sources including Lumus Ltd. (Ness Ziona, Israel). Therefore, the structure of the light guide 20 itself will not be described in detail here.

[0052] In the device design shown here, waveguide 30 is tilted relative to the extension direction of the partial reflective surface 45 within waveguide 20 to generate vertical propagation within waveguide 20. In some cases, it may be desirable to employ other offset angles between the two waveguides (e.g., tilting about a “roll” axis along the extension direction of waveguide 30) to provide an improved optical coupling configuration between the two waveguides. Various modified coupling options that may also be employed here are described, particularly in Figures 19 to 26, in PCT Patent Application Publication No. WO 2018 / 065975 A1 (which was published after the priority date of this application and does not constitute prior art to this application), and will not be discussed here for the sake of brevity.

[0053] This example uses the above reference. Figure 1BThe coupling geometry is described. A coupling prism 11 is added to minimize chromatic aberration. An air gap or other low-index coupling material is provided between the coupling prism 11 and the wedge-shaped surface 21 to maintain total internal reflection characteristics at the wedge-shaped surface 21.

[0054] Turn now Figures 3A to 4 These figures illustrate how a greater aperture extension can be achieved using two or more stacked waveguides. In these figures, three stacked waveguides 30a, 30b, and 30c (each waveguide similar to waveguide 30 described so far) are arranged such that the projected input image is partially coupled to each waveguide. The waveguides are of different lengths, resulting in a staggered coupling wedge configuration, most preferably having a generally coplanar wedge-shaped surface 22 as shown, thereby providing coverage across the entire "width" dimension of the optical guide 20, which itself provides a second dimension of aperture extension, as described above. Figures 2A to 2B As shown in the diagram, an air gap or other internal reflection retention layer or multilayer structure is arranged between waveguides 30a, 30b, and 30c to maintain the internal reflection characteristics of these waveguides. At least in the coupling region, the boundary between the waveguides must be transparent to low-angle light to allow coupled light to pass through the interface. In other regions, a metallic reflective layer or other reflective layer may be used between the waveguides.

[0055] like Figure 3B As can be seen, the image illumination (light rays b1 and / or b2) coupled out from the wedge-shaped surfaces 22 of the upper waveguides 30b and 30c passes through the lower waveguide, where the front 14a and rear 14b serve as extensions of the optical guide 20 in the front-to-back direction. Figure 3A In the cross-sectional view, for clarity, the rays b1 to b2 and c1 to c4 in the upper waveguide have been omitted, but these rays are still present.

[0056] Figure 3BThe coupling configuration of the device is based on partial reflection from the wedge-shaped surface 21. Specifically, the wedge-shaped surfaces 21 of waveguides 30c and 30b are coated to be partially reflective, such that when a projected image is input as shown, a portion of the image illumination is deflected and coupled into waveguide 30c, a portion is transmitted and coupled into waveguide 30b, and a portion is transmitted through both waveguides 30c and 30b and coupled into waveguide 30a. The wedge-shaped surface 21 of waveguide 30a can be a full (i.e., close to 100%) reflector. To minimize distortion in the transmitted portion of the image illumination, a filler prism 31 is preferably deployed to substantially fill the wedge-shaped gap between the coupling configurations. The filler prism 31 can be integrated as an extension of the waveguide and can be separated from the underlying waveguide by the air gap shown. In some cases, for example, a coupling prism 32 can be provided to benefit the coupling geometry and minimize chromatic aberration.

[0057] Figure 4 It shows the relationship with Figure 3B Similar but based on Figure 1B The device architecture is based on the principle of coupling arrangement. In this case, partial coupling to multiple waveguides is achieved by applying a partially reflective coating to a portion of surface 12a, and the image is introduced from one side of the wedge-shaped surface 21. The uppermost waveguide 30c can employ a total reflection coating on the relevant portion of surface 12a. A filler wedge 31 is again provided, but it is shown here as being spaced apart from the wedge-shaped surface 21 by an air gap to maintain the TIR characteristics of surface 21, thereby providing low-loss transmission of the injected image illumination while capturing reflected rays. A coupling prism 11 is provided.

[0058] Although the embodiments of the invention shown so far all employ a first reflection from the first wedge-shaped surface 21 to couple image illumination into the waveguide (as light patterns a1 to a4), this is not a necessary feature, and alternative coupling arrangements may be preferred. As an example, Figure 5A and Figure 5B The following coupling arrangement is illustrated: In this arrangement, the coupling prism 40 is adjacent to or abuts the coupling region of the first waveguide 30 to provide a tilted input surface 42, which is correctly oriented to allow direct image injection along an image injection direction corresponding to one of the rays a1 to a4, wherein the remaining three conjugate rays are generated by internal reflection from the waveguide surface. One of these conjugate rays is reflected from the wedge-shaped surface 21 to generate one of the second mode rays c1 to c4, wherein the other three conjugate rays are regenerated by internal reflection within the waveguide.

[0059] The coupling prism 40 preferably includes at least one surface, and preferably two surfaces 44 and 46, which are coplanar extensions of corresponding surfaces of the first waveguide (which may be the shown surfaces 12b and 14b), or in some cases the coupling prism may include a wedge-shaped surface 21. These extended surfaces facilitate “filling” the waveguide with image illumination. In this implementation, the propagation of the first modes corresponding to rays a1 to a4 is directly injected into the waveguide (by injecting one of these images), while the second modes corresponding to rays c1 to c4 are formed by reflecting one of these images onto the wedge-shaped surface 21 and then generating a conjugate image through internal reflection.

[0060] Figure 5A and Figure 5B The implementation methods are basically similar, except that... Figure 5A The implementation of wedge-shaped surfaces 21 and 22 being inclined at an angle relative to both the first pair of parallel surfaces 12a, 12b and the second pair of parallel surfaces 14a, 14b is shown. Figure 5B The implementation of wedge-shaped surfaces 21 and 22 at an angle relative to the first pair of parallel surfaces 12a, 12b and perpendicular to the second pair of parallel surfaces 14a, 14b is shown.

[0061] Turn now Figures 6A to 8C These figures illustrate a second aspect of the invention, according to which the first and second wedge-shaped surfaces are not parallel surfaces because the image illumination is deflected between the first and second wedge-shaped structures. In the case shown here, the deflection occurs at a series of partially reflective tilted inner surfaces within the first waveguide, wherein this series of partially reflective tilted inner surfaces achieves aperture expansion in the first dimension and redirects the image illumination toward the second waveguide.

[0062] Three non-limiting examples of this implementation will now be described. In each case, an optical device including a first optical waveguide 140 is shown, the first optical waveguide 140 having at least a pair of parallel surfaces for guiding light by internal reflection. The optical waveguide 140 includes a series of mutually parallel partially reflective surfaces 150 oriented not parallel to the paired parallel surfaces. The optical waveguide 140 also includes a wedge-shaped configuration formed between a first wedge-shaped surface 125 and one of the parallel surfaces. This wedge-shaped configuration is configured to provide image illumination coupling to generate two different modes (or angular ranges) for propagating the image within the waveguide, as described in the previous embodiments with respect to the wedge-shaped surface 21. In this case, instead of propagating directly to the coupling wedge, the light rays corresponding to the two propagation modes of the image are deflected at the partially reflective surfaces 150 to the corresponding deflection directions for coupling out from the first optical waveguide.

[0063] The second optical waveguide 145 has a pair of parallel surfaces for guiding light via internal reflection and is configured to receive portions of the injected image propagating in directions corresponding to the two modes of image propagation deflected from surface 150. The second optical waveguide 145 includes a coupling wedge-shaped structure formed between the second wedge-shaped surface 122 and one of the parallel surfaces. This coupling wedge-shaped structure couples the two modes of image propagation in a manner entirely similar to the wedge-shaped surface 22 described above. When used as part of an augmented reality display, the wedge-shaped surface 122 is preferably implemented with a partially reflective coating, and complementary wedge prisms (not shown) can be added to provide a distortion-free view of the real world via the wedge-shaped structure.

[0064] exist Figures 6A to 6C and Figures 7A to 7B In this case, the first optical waveguide 140 is a rectangular waveguide in which image illumination is propagated by quadruple internal reflection, as described above with respect to waveguide 30. Figures 6A to 6C In the middle, the coupled wedge-shaped structure is in Figure 6A The best view is from the top view, while the coupled wedge-shaped structure is in Figure 6B It is best seen in the side view. It can also be seen in conjunction with the above. Figure 1B A similar alternative implementation is used, coupled via a wedge-shaped surface 125. Here, the orientation of the partial reflective surface 150 is most preferably inclined relative to the top and bottom surfaces of the waveguide 140 and perpendicular to the front and rear surfaces, as shown below. Figure 8C As shown.

[0065] Figure 7A and Figure 7B The implementation method in [the document] is similar in structure and function to [the previous one]. Figures 6A to 6C The implementation method employs different orientations of the coupling wedge, which provides additional flexibility in terms of product design compactness and ergonomics. Considering the quadruple reflections that occur during image propagation within the waveguide, in some cases a conjugate image with the desired orientation can be selected for coupling to the eye. In cases where the coupled image is an inverted image, this can be electronically compensated for by inverting the generated image, ensuring the coupled image is correctly oriented. Generally, the partially reflecting surface 150 is tilted relative to the two pairs of parallel outer surfaces of the waveguide.

[0066] Final turn Figures 8A to 8C These diagrams illustrate the relationship with Figures 6A to 6C The implementation method is similar to the implementation method, but in Figures 8A to 8C The first waveguide section 140 is a plate waveguide that guides image illumination in only one dimension between a pair of parallel planes. In the other dimension (e.g., Figure 8B and Figure 8CIn the upper and lower dimensions shown, the image projected within waveguide 140 unfolds according to its angular field of view and should not reach the end of the waveguide. Therefore, waveguide 140 typically needs to be slightly larger in the non-guided dimension than in previous implementations. Since internal reflection between waveguide 140 and waveguide 145 is not required (or desired), these elements can optionally be unified or optically combined into a single waveguide plate without inserting any air gaps or other optical elements. In all other respects, Figures 8A to 8C The structure and operation of the implementation method are similar to those described above. Figure 6A and Figure 6C The implementation method in the text.

[0067] In all the above embodiments, the described device is used in combination with multiple additional components to form a complete product. Thus, for example, wherever the light associated with the coupled image illumination is shown in the figures, this light is typically provided by a miniature image projector or “POD,” which generally includes an illumination source, a spatial light modulator such as an LCoS chip, and collimating optics, which are typically integrated onto the surface of a beam splitter prism block structure. Such image projectors are well-known and commercially available, and therefore will not be described in detail here.

[0068] Similarly, in the case of near-eye displays, the final product is typically integrated with a support structure, which may include a frame-type structure supported by the wearer's ears and nose, or a head-mounted structure such as a headband or helmet. All of these structures are well known and therefore do not need to be described herein.

[0069] This invention also includes the following technical solutions:

[0070] Option 1. An optical device, comprising:

[0071] A first optical waveguide having an elongation direction, the first optical waveguide having a first pair of parallel surfaces and a second pair of parallel surfaces, the first pair of parallel surfaces and the second pair of parallel surfaces being parallel to the elongation direction, forming a rectangular cross-section for guiding light through quadruple internal reflection at the first pair of parallel surfaces and the second pair of parallel surfaces, each ray undergoing internal reflection thereby defining a set of four conjugate propagation directions, at least a portion of the first optical waveguide being defined by a first wedge-shaped surface and a second wedge-shaped surface.

[0072] The first wedge-shaped surface is configured such that light rays corresponding to at least a portion of an injected image propagating in the first set of conjugate propagation directions within the first optical waveguide are deflected by reflection at the first wedge-shaped surface and propagated in a second set of conjugate propagation directions, wherein the second direction forms a smaller angle with the elongation direction compared to the first direction.

[0073] Furthermore, the second wedge-shaped surface is parallel to the first wedge-shaped surface to deflect an image propagating along at least one of the second set of conjugate directions to propagate along at least one of the first set of conjugate directions, and to couple an image propagating along one of the first set of conjugate directions to exit from the first optical waveguide.

[0074] Scheme 2. The optical device according to Scheme 1, wherein the first wedge-shaped surface is the outer surface of the first optical waveguide.

[0075] Option 3. The optical device according to Option 1, wherein the first wedge-shaped surface is coated with a reflective coating.

[0076] Option 4. The optical device according to Option 1, wherein the first wedge-shaped surface is coated with a partially reflective coating.

[0077] Option 5. The optical device according to Option 1, wherein the first wedge-shaped surface is light-transmitting, and wherein at least the portion of the parallel surface facing the first wedge-shaped surface is coated with a reflective coating.

[0078] Option 6. The optical device according to Option 1, wherein the injected image introduced into the first optical waveguide is deflected from the injection direction to a direction in the first set of conjugate directions by a first reflection from the first wedge-shaped surface, and after additional reflection from at least one of the parallel planes, is further deflected from a direction in the first set of conjugate directions to a direction in the second set of conjugate directions by a second reflection from the first wedge-shaped surface.

[0079] Option 7. The optical device according to Option 1 further includes a coupling prism adjacent to or adjacent to the coupling region of the first waveguide, the coupling prism including at least one surface extending from a corresponding surface of the first waveguide.

[0080] Option 8. The optical device according to Option 1 further includes a light guide having two principal parallel surfaces, wherein the first waveguide is deployed such that an image coupled out from the first waveguide is coupled into the light guide to propagate within the light guide by internal reflection at the two principal parallel surfaces, the light guide further including a coupling arrangement for coupling out the image propagating within the light guide to direct the image toward the user's eye.

[0081] Option 9. The optical device according to Option 1 further includes a second optical waveguide having a first pair of parallel surfaces and a second pair of parallel surfaces. The first pair of parallel surfaces and the second pair of parallel surfaces of the second optical waveguide are parallel to the elongation direction, forming a rectangular cross-section for guiding light through quadruple internal reflection at the first pair of parallel surfaces and the second pair of parallel surfaces. At least a portion of the second optical waveguide is defined by a first wedge-shaped surface and a second wedge-shaped surface.

[0082] The first and second optical waveguides are deployed in a stacked relationship and configured such that a projected image having a first aperture size is partially coupled into each of the first and second optical waveguides, and such that the second wedge-shaped surface of the first and second optical waveguides each serves as part of a coupling configuration, the coupling configuration being deployed to provide an effective output aperture having a size larger than the first aperture size.

[0083] Option 10. The optical device according to Option 9, wherein, for each of the first optical waveguide and the second optical waveguide, a portion of the first wedge-shaped surface and one of the parallel surfaces that faces the first wedge-shaped surface forms a coupling configuration, the optical device further comprising a filling prism that substantially fills the wedge-shaped gap between the coupling configurations.

[0084] Option 11. The optical device according to Option 10, wherein the first wedge-shaped surface of the second optical waveguide is coated to partially reflect, thereby coupling a portion of the projected image and allowing a portion of the projected image to reach the first coupling configuration.

[0085] Option 12. The optical device according to Option 10, wherein the portion of one of the parallel surfaces that faces the first wedge-shaped surface of the first optical waveguide is coated to partially reflect, thereby coupling a portion of the projected image and allowing a portion of the projected image to reach the second coupling configuration.

[0086] Option 13. The optical device according to Option 9, wherein the first optical waveguide and the second optical waveguide are part of a stack of at least three optical waveguides.

[0087] Option 14. The optical device according to Option 9, wherein the image coupled from the second optical waveguide propagates through the first optical waveguide.

[0088] Option 15. The optical device according to Option 1, wherein the first wedge-shaped surface and the second wedge-shaped surface of the first optical waveguide are inclined at an oblique angle relative to the first pair of parallel surfaces and perpendicular to the second pair of parallel surfaces.

[0089] Option 16. The optical device according to Option 1, wherein the first wedge-shaped surface and the second wedge-shaped surface of the first optical waveguide are inclined at an oblique angle relative to both the first pair of parallel surfaces and the second pair of parallel surfaces.

[0090] Option 17. An optical device, comprising:

[0091] A first optical waveguide portion having at least a first pair of parallel surfaces for guiding light by internal reflection, the first optical waveguide including a plurality of mutually parallel partially reflective surfaces oriented not parallel to the paired parallel surfaces.

[0092] A wedge-shaped structure is formed between a first wedge-shaped surface and one of the parallel surfaces. The wedge-shaped structure is configured such that light rays corresponding to at least a portion of an injected image propagating in a first direction within the first optical waveguide are deflected at the first wedge-shaped surface and propagated in a second direction. The angle between the second direction and the elongation direction of the first optical waveguide is smaller than that of the first direction. Light rays in the first direction and light rays in the second direction are respectively deflected at the partially reflecting surface to a first deflection direction and a second deflection direction to couple out of the first optical waveguide.

[0093] The second optical waveguide has a second pair of parallel surfaces for guiding light by internal reflection. The second optical waveguide is deployed to receive portions of the injected image propagating along the first deflection direction and the second deflection direction.

[0094] The second optical waveguide includes a coupling wedge structure formed between the second wedge-shaped surface and one of the second pair of parallel surfaces. The coupling wedge structure is deployed to couple out at least a portion of the image that propagates along the first deflection direction by a single reflection from the wedge-shaped surface and that propagates along the second deflection direction by being reflected twice from the wedge-shaped surface.

[0095] It should be understood that the above description is intended to be illustrative only, and many other embodiments may exist within the scope of the invention as defined in the appended claims.

Claims

1. An optical device, comprising: A first optical waveguide portion and a second optical waveguide portion, the first optical waveguide portion having at least a first pair of parallel surfaces for guiding light by internal reflection, and the first optical waveguide portion having a plurality of mutually parallel partially reflective surfaces oriented not to be parallel to the pair of parallel surfaces disposed inside the first optical waveguide portion. A coupled wedge structure is formed between one of the parallel planes and a first wedge-shaped surface. The coupled wedge structure is configured such that two parallel, non-overlapping light rays corresponding to a portion of an injected image incident from within the first optical waveguide along a first direction onto the first wedge-shaped surface are deflected along a second direction by reflection at the first wedge-shaped surface. The second direction forms a first angle of incidence relative to the one of the parallel planes. A first ray of light propagates through internal reflection at the first angle of incidence at the paired parallel planes, and a second ray of light, after reflection at the one of the parallel planes, undergoes a second reflection from the wedge-shaped surface and is deflected along a third direction having a second angle of incidence relative to the one of the parallel planes, the second angle of incidence being greater than the first angle of incidence. The second ray propagates through internal reflection at the second angle of incidence at the paired parallel planes. Both the first and second rays are deflected toward the second optical waveguide at the partially reflecting surface. The second optical waveguide has a second pair of parallel surfaces. The second optical waveguide is deployed to receive the first and second light rays after deflection at the partially reflective surface, and to guide the first and second light rays through internal reflection at the second pair of parallel surfaces. The second optical waveguide includes a coupling wedge structure formed between one of the parallel planes of the second pair of parallel planes and the second wedge-shaped surface. The coupling wedge structure is deployed to couple the first light from the second optical waveguide by a single reflection from the second wedge-shaped surface and to couple the second light from the second optical waveguide by a double reflection from the second wedge-shaped surface.

2. The optical device according to claim 1, wherein, The first wedge-shaped surface is the outer surface of the first optical waveguide.

3. The optical device according to claim 1, wherein, The first wedge-shaped surface is coated with a reflective coating.

4. The optical device according to claim 1, wherein, The first wedge-shaped surface is coated with a partially reflective coating.

5. The optical device according to claim 1, wherein, The first wedge-shaped surface is translucent, and at least a portion of one of the first paired parallel surfaces that faces the first wedge-shaped surface is coated with a reflective coating.

6. The optical device according to claim 1, wherein, The first optical waveguide portion and the second optical waveguide portion are integrated into a single optical waveguide, such that each of the second pair of parallel surfaces is a continuation of the corresponding one of the first pair of parallel surfaces.

7. The optical device according to claim 1, wherein, The injected image introduced into the first optical waveguide is deflected from the injection direction to a direction from the first set of conjugate directions by a first reflection from the first wedge-shaped surface, and after additional reflection from at least one of the parallel planes, it is further deflected from the direction from the first set of conjugate directions to a direction from the second set of conjugate directions by a second reflection from the first wedge-shaped surface.

8. The optical device according to claim 1, further comprising a coupling prism adjacent to or adjacent to the coupling region of the first optical waveguide, the coupling prism comprising at least one surface extending from a corresponding surface of the first optical waveguide.

9. The optical device according to claim 1, wherein, The first optical waveguide has a third pair of parallel surfaces, which are perpendicular to the first pair of parallel surfaces and form a rectangular cross section. This cross section is used to guide the first light ray and the second light ray through quadruple internal reflection at the first pair of parallel surfaces and the third pair of parallel surfaces.

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