Optical guide optical assembly

Abstract

This provides an optical assembly with an enlarged optical aperture. [Solution] The optical assembly combines facet reflection technology with diffraction technology. At least two diffraction components having opposing (matching) optical powers are used, so that the chromatic dispersion introduced by the first diffraction component is subsequently canceled out by the second diffraction component. Compared to conventional technology, the two diffraction components are used in combination with reflective optics to achieve more efficient aperture expansion (for near-eye displays), thereby reducing distortion and noise, and also reducing design constraints on the system and individual components. The assembly eliminates and / or reduces the need for polarization management while enabling a wider field of view. Furthermore, because the distortion patterns of the two technologies are not correlated, non-uniformity can be reduced in embodiments compared to conventional single-technology implementations.

Description

Technical Field

[0001] The present invention generally relates to optical assemblies, and more particularly to the expansion of optical apertures.

Background Art

[0002] Referring to A of FIG. 7, a rough schematic diagram of a conventional expansion of an optical aperture using a diffractive component in a waveguide is shown. In the current figure, the incident light (image) is perpendicular from outside the page to the page. The coupling-in element (1001) couples the incident light to the lateral expansion element (1002), and the lateral expansion element (1002) expands the light laterally (from left to right in the current figure). Thereafter, the laterally expanded light is coupled to the vertical expansion element (1003), and the vertical expansion element (1003) expands the light vertically (from top to bottom in the current figure) and couples that light out to the user (viewer's eye).

[0003] Conventional diffractive elements introduce chromatic dispersion in which light rays with various wavelengths diffract at various angles. A narrow-band light source (such as a laser) can be used to reduce the chromatic dispersion. A more practical solution is to design diffractive components to cancel each other's dispersion.

[0004] Referring to B of FIG. 7, a diagram of the diffraction directions of FIG. 7A of light propagating in an angular region (angular interval) is shown. The dashed arrows and the solid arrows represent two different typical wavelengths. The starting angle of region (1005) represents the angle of the light ray when the light ray hits the first diffractive element (coupling-in element (1001)) where the light ray is coupled to the optical guide. Region (1007) represents the direction of the light ray after the coupling-in element (1001), region (1009) represents the direction of the light ray after the lateral expansion element (1002), and region (1005) further represents the angle of the light ray after coupling from the optical guide by the vertical expansion element (1003). The direction of the light ray entering the optical guide is equal to the direction of the light ray coupled from the optical guide in order to minimize chromatic dispersion. As various wavelengths of light propagate within the optical guide, the various wavelengths have different directions and have the same direction when output from the optical guide.

[0005] Basic Technology Figure 1 illustrates a conventional foldable optical structure, where a substrate (2) is illuminated by a display source (4). The display is collimated by a collimating optical system (6) (e.g., a lens). Light from the display source (4) is coupled to the substrate (2) by a first reflecting surface (8) such that the main rays (11) are parallel to the substrate plane. A second reflecting surface (12) couples the light from the substrate to the viewer's eye (14). Despite its compact size, this structure suffers from significant drawbacks, most notably its inability to achieve a very limited field of view (FOV).

[0006] Referring here to Figure 2, a side view of a typical optically guided element (LOE) is shown. To alleviate the above limitations, an array of selective reflective surfaces can be used and manufactured within the optically guided element (LOE). The first reflective surface (16) is illuminated by a collimated display ray (beam) (18) emitted from a light source (not shown) located behind the device. For the sake of brevity in the drawings, only one ray, namely the incident ray (38) (also called the “beam” or “incident ray”), is generally depicted. Other rays of incident light, such as beams (18A) and (18B), may also be used to specify the edges of the incident pupil, such as the left and right edges of the incident pupil. Generally, whenever an image is represented herein by rays, it should be noted that the rays are sample beams of the image, which are typically formed by multiple beams at slightly different angles, each corresponding to a point or pixel of the image. Unless specifically referred to as the tip of the image, the illustrated beams are typically the centroid of the image.

[0007] The reflective surface (16) reflects incident light from the light source, and the incident light is captured inside the optical guide (20) by internal total internal reflection. The optical guide (20) is also called a “waveguide,” “planar substrate,” and “optical transmission substrate.” The optical guide (20) includes at least two (principal) surfaces that are parallel to each other, shown in the drawings as the rear (principal) surface (26) and the front (principal) surface (26A). Note that the designations “front” and “rear” for the principal surfaces (26) and (26A) are for convenience of reference, as the optical guide (20) is usually symmetric (and therefore the references to the principal surfaces (26) and (26A) can be swapped to produce the same result). In the context of this specification, the optical guide (20) is called a one-dimensional (1D) waveguide and guides an injected image by only one dimension between a pair of parallel surfaces (in this case, principal surfaces (26) and (26A)).

[0008] The incident light ray (38) enters the substrate at its proximal end (right side of the figure). The light propagates toward the distal end of the optical guide (left side of the figure) through the optical guide and one or more facets, usually at least several facets, and typically several facets. The light propagates through the optical guide in both the initial propagation direction (28) and the alternative propagation direction (30).

[0009] After several reflections from the surface of the substrate (20), the captured wave reaches an array of selective reflectors (22), which connect the light from the substrate to the viewer's eye (24). In an alternative structure, the selective reflectors (22) enter the substrate immediately after the light ray (18) without first reflecting from the surface of the substrate (20).

[0010] Internal partial reflective surfaces, such as the selective reflective surface (22), are generally referred to as “facets” in the context of this specification. In extreme cases, facets can be fully reflective (100% reflectivity or mirror, e.g., the last facet at the distal end of the substrate) or minimally reflective. For enhanced real-world applications, the facets are partially reflective, allowing light from the real world to enter through the upper surface (26A), traverse the substrate containing the facets, and exit the substrate through the lower surface (26) to the viewer’s eye (24). For virtual reality applications, the facets may have alternative reflectivity, such as a first internally linked mirror with 100% reflectivity, because image light from the real world does not need to traverse this mirror. The internal partial reflective surface (22) generally traverses the optical guide (20) at least partially at an oblique angle (i.e., neither parallel nor perpendicular) to the direction of extension of the optical guide (20).

[0011] References to reflectance generally refer to nominal reflectance. Nominal reflectance is the total internal reflection required at a particular location in the substrate. For example, when the reflectance of a facet is mentioned as 50%, this generally refers to 50% of its nominal reflectance. If the nominal reflectance is 10%, then 50% reflectance results in a 5% reflectance for that facet. Those skilled in the art will understand the use of reflectance percentages from the context of use. Partial reflection can be achieved by various techniques, but are not limited to, the use of a certain percentage of light transmission or polarization.

[0012] Figures 3A and 3B illustrate the desired reflectivity behavior of the selected reflective surface. In Figure 3A, the light ray (32) is partially reflected from the facet (34) and connected to the substrate (20) (38B). In Figure 3B, the light ray (36) is transmitted through the facet (34) with no significant reflection.

[0013] Figure 4A is a detailed cross-sectional view of an array of selective reflective surfaces that connect light to a substrate and then to the viewer's eye. As shown in the figure, a ray (38) from the light source (4) strikes the first partial reflective surface. A portion of the ray (41) continues in its original direction and is connected from the substrate. Another portion of the ray (42) is connected to the substrate by internal total internal reflection. The captured ray is gradually connected outward from the substrate at point (44) by the other two partial reflective surfaces (22). The coating properties of the first reflective surface (16) do not necessarily have to be similar to those of the other reflective surfaces (22), (46). This coating could be metallic, dichroic, or a hybrid metallic-dichroic, simpler beam splitter. Similarly, in a non-see-through system, the last reflective surface (46) could be a simple mirror.

[0014] Figure 4B is a detailed cross-sectional view of the apparatus including an array of reflective surfaces, where the last reflective surface (46) is a total reflection mirror. The leftmost portion of the last reflective surface (46) cannot be optically active in this case and cannot connect peripheral rays (48) from the substrate. Consequently, the output aperture of the device is slightly smaller. However, the optical efficiency is much higher and the manufacturing process of the LOE can be much simpler.

[0015] It is important to note that, unlike the structure shown in Figure 2, there are constraints on the orientation of the reflective surfaces (16) and (22). In the previous structure, all light is coupled internally within the substrate by the reflective surface (16). Therefore, surface (16) does not need to be parallel to surface (22). Furthermore, the reflective surfaces may be oriented so that the light is coupled outward from the substrate in the direction opposite to the direction of the input wave. In the structure illustrated in Figure 4A, however, some of the input light is not reflected by surface (16), but continues in the original direction of the input light (38) and is immediately coupled outward from the substrate as output light (41). Therefore, not only must all the reflective surfaces (22) be parallel to each other, but surface (16) must also be parallel to surface (22) so that all rays starting from the same plane wave have the same output direction.

[0016] Referring again to Figure 4A, a system with two reflective surfaces for coupling light from the substrate is shown; however, any number of reflective surfaces can be used depending on the required output aperture of the optical system and the thickness of the substrate. Naturally, there are cases where only one external coupling surface is required. In that case, the output aperture is effectively twice the size of the system's input aperture. The only reflective surfaces required for the last structure are a simple beam splitter and mirror.

[0017] In the apparatus shown in this figure, light from the display source is connected to the substrate at the edge of the substrate, but there is a preferred system that has a symmetrical structure. That is, the input light should be connected to the substrate at the center of the substrate.

[0018] Figure 4C is a diagram illustrating a detailed cross-sectional view of a one-dimensional (1D) optical guide for lateral pupil dilation with a symmetrical structure. This figure illustrates how two identical substrates are combined to produce a symmetrical optical module. As can be seen, some of the light from the light source (4) passes directly through the partial reflective surface and exits the substrate. Other portions of the light are coupled to the right side (20R) and left side (20L) of the substrate by the partial reflective surfaces (16R) and (16L), respectively. The captured light is then gradually coupled outward by the reflective surfaces (22R) and (22L), respectively. Clearly, the output aperture is three times the size of the system's input aperture, the same magnification as described in Figure 5B. However, unlike the previous system, the system here is symmetrical with respect to the junction surface (29) of the right and left substrates.

[0019] Referring here to Figures 5A and 5B, typical implementations of Figures 4B and 4C are shown (on top of) the optical guide. The configurations of Figures 4B and 4C are laterally magnified versions of the incident image. The apparatus in Figure 4B is used to implement the first LOE(20a) in Figure 5A, the apparatus in Figure 4C is used to implement the first LOE(20a') in Figure 5B, and the apparatus in Figure 2 may be used to implement the second LOE(20b).

[0020] Figure 5A illustrates an alternative method for expanding a beam along two axes using a dual LOE configuration. The input wave (90) is coupled by a first reflector (16a) to a first LOE (20a) having an asymmetric structure similar to the one illustrated in Figure 4B, and then propagates along the η-axis. A partial reflector (22a) couples the light as it exits the first LOE (20a), and the light is then coupled by a reflector (16b) to a second asymmetric LOE (20b). The light then propagates along the ξ-axis and is then externally coupled by a selective reflector (22b). As shown, the original beam (90) is expanded along both axes, where the overall expansion is determined by the ratio between the lateral dimensions of elements (16a) and (22b). The configuration given in Figure 5A is simply an example of a dual LOE setup. Furthermore, other configurations are possible in which two or more LOEs are combined to form complex optical systems.

[0021] Referring here to Figure 5B, a diagram is shown illustrating another method for expanding the beam along two axes using a dual LOE configuration. Typically, the region where light is coupled to the second LOE (20b) by the surface (16b) cannot be transparent to external light and is not part of the see-through region. Therefore, the first LOE (20a) does not need to be transparent. As a result, even with respect to see-through systems, it is usually possible to design the first LOE (20a) to have a symmetrical structure, as can be seen in this figure. The second LOE (20b) has an asymmetrical structure that allows the user to see the outside. In this configuration, a portion of the input beam (90) continues along its original direction (92) to the internally connected mirror (16b) of the second LOE (20b), while the other portion (94) is connected to the first LOE (20a') by a reflecting surface (16a), propagates along the η-axis, and is then connected to the second LOE (20b) by a selective reflecting surface (22a). Subsequently, both portions are connected to the second asymmetric LOE (20b) by a reflecting surface (16b), propagates along the ξ-axis, and is then connected by a selective reflecting surface (22b).

[0022] Figure 6 illustrates an example of LOE(20a) / (20a') and (20b) embedded in a standard eyeglass frame (107). The display source (4), folding optics, and collimating optics (6) are assembled inside the arm portion (112) of the eyeglass frame, directly beside the LOE(20a) / (20a'), located at the edge of the second LOE(20b). If the display source is an electronic device such as a small CRT, LCD, or OLED, the drive electronics (114) for the display source may be assembled inside the rear portion of the arm (112). The power and data interface (116) can be connected to the arm (112) by a lead (118) or other means of communication, including wireless or optical transmission. Alternatively, the battery and small data link electronics may be integrated into the eyeglass frame. This figure is an example, and other possible head-mounted display configurations can be constructed, including assemblies in which the display source is mounted parallel to the LOE plane or above the LOE.

[0023] Further details of this basic technology can be found in U.S. Patent No. 7,643,214 and PCT / IL 2018 / 050025, which has not been published and does not constitute prior art to the present invention. [Overview of the project]

[0024] According to the teachings of this embodiment, an apparatus for expanding an optical aperture is provided, the apparatus comprising at least one optical guide; a set of three optical components associated with at least one optical guide, comprising a pair of first and second matching diffractive optical components; and a set of three optical components comprising a reflective optical component comprising a plurality of partially reflective, parallel planes; and a cooperating optical component for expanding internally coupled light into externally coupled light, wherein the internally coupled light is coupled to at least one optical guide, and the expansion is two-dimensional.

[0025] In an optional embodiment, the first optical component of the set is configured to direct light interconnected in a first direction of expansion within a first optical guide, thereby generating first expanded light; the second optical component of the set is configured to couple the first expanded light to a second optical guide in a second direction of expansion, thereby generating second expanded light; and the third optical component of the set is configured to externally couple the second expanded light as externally coupled light in a third direction; wherein the first, second and third directions are not parallel to each other.

[0026] Another optional embodiment further includes a diffractive optical component configured to direct light as interconnected light to at least one optical guide; wherein the at least one optical guide is one optical guide, and the one optical guide is configured to direct light interconnected in a first direction of expansion within the one optical guide, thereby generating first expanded light, a first diffractive optical component; a second diffractive optical component configured to expand the first expanded light in the one optical guide in a second direction of expansion, thereby generating second expanded light; and a reflective optical component configured to externally couple the second expanded light as externally coupled light in a third direction; wherein the first, second and third directions are not parallel to each other.

[0027] Another optional embodiment further includes a pair of third and fourth matching diffractive optical components; and a pair of fifth and sixth matching diffractive optical components.

[0028] In another optional embodiment, each of the matching pairs of optical components has a different diffraction interval from the other matching pairs of optical components, and the diffraction interval is such that each of the matching pairs of optical components deflects different wavelengths at a similar angle from the other matching pairs of optical components.

[0029] In another optional embodiment, the wavelengths are red, green, and blue light.

[0030] In another optional embodiment, the first optical guide of at least one optical guide includes a pair of first and second matching diffractive optical components; the second optical guide of at least one optical guide includes a pair of third and fourth matching diffractive optical components; and the third optical guide of at least one optical guide includes a pair of fifth and sixth matching diffractive optical components.

[0031] In another optional embodiment, a reflective optical component is configured to magnify the internally connected light in a first direction of magnification within a first optical guide, thereby generating a first magnified light; first, third, and fourth diffractive optical components are configured to magnify each wavelength of the first magnified light in their respective first, second, and third optical guides in a second direction of magnification, thereby generating their respective second magnified light; and second, fourth, and sixth diffractive optical components are configured to externally connect their respective second magnified light as externally connected light in a third direction; where the first, second, and third directions are not parallel to each other. [Brief explanation of the drawing]

[0032] This embodiment is described herein as merely one example with reference to the accompanying drawings. [Figure 1] This is a side view of a prior art foldable optical device. [Figure 2] This is a side view of a typical optical guide element. [Figure 3] A and B illustrate the desired reflection and transmittance characteristics of a selected reflective surface for two ranges of incidence angles. [Figure 4] A is a diagram illustrating a typical configuration of an optical guide element, B is a diagram illustrating another configuration of an optical guide element, and C is a diagram illustrating a detailed cross-sectional view of a lateral pupil dilation one-dimensional optical guide with a symmetrical structure. [Figure 5]Diagram A illustrates a method of expanding rays along two axes using a dual LOE configuration, and diagram B illustrates another method of expanding rays along two axes using a dual LOE configuration. [Figure 6] An example of LOE embedded in a standard eyeglass frame is shown. [Figure 7] Figure A is a rough schematic of conventional optical aperture expansion using a diffraction component in a waveguide, and Figure B is a diagram of the diffraction direction of light propagating in the angular domain in Figure 7A. [Figure 8] Figures A and B are rough side and front views of typical embodiments of diffraction-reflection-diffraction, respectively; Figure C is a rough diagram of a typical embodiment of reflection-diffraction; and Figure D is a diagram of the diffraction direction of light propagating in the angular domain in Figures 8A and 8B. [Figure 9] A and B are rough schematic side and front views, respectively, of typical embodiments of diffraction-diffraction-reflection, and C is a diagram of the diffraction direction of light propagating in the angular domain in Figures 9A and 9B. [Figure 10] Figures A and B are rough schematic diagrams of typical side and front views of diffraction-reflection embodiments, respectively. [Figure 11] A and B are rough side and front views of typical embodiments of diffraction-diffraction-reflection, respectively, and C is a rough front view of a typical embodiment of the overlapping diffraction-reflection-diffraction. [Figure 12] A and B are side and front views, respectively, of rough schematic diagrams of typical embodiments of diffraction-reflection, and C is a front view of a rough schematic diagram of a typical embodiment of diffraction-diffraction-reflection. [Figure 13] A and B are rough schematic diagrams of a typical embodiment of diffraction-diffraction-reflection, with separate lateral expanders for diffraction, in side and front views, respectively. [Figure 14]A and B are side and front views, respectively, of rough schematic diagrams of typical embodiments of diffraction-reflection, and C is a front view of a rough schematic diagram of a typical embodiment of diffraction-diffraction-reflection. [Figure 15] A, B, and C are side, front, and top views, respectively, of rough schematic diagrams of typical embodiments of reflection-diffraction-diffraction, and D is a diagram of the diffraction directions of light propagating in the angular domain in Figures 15A, 15B, and 15C.

[0033] Abbreviations and definitions For convenience of reference, this section contains a brief list of abbreviations, acronyms, and short definitions used herein. This section should not be considered to limit the invention. A more complete explanation can be found below and in applicable standards. 1D - one dimension 2D - two dimensions CRT - cathode ray tube EMB - iMotion Box FOV - field of view HMD - Head-Mounted Display HUD - Head-Up Display LCD - Liquid Crystal Display LOE - Optical Guide Element OLED - Organic Light-Emitting Diode Array OPL - Optical path length SLM - Spatial Light Modulator TIR - total internal reflection [Modes for carrying out the invention]

[0034] Detailed explanation - from Figure 8A to Figure 15D The principles and operation of the apparatus described in this embodiment may be fully understood by referring to the drawings and accompanying descriptions. The present invention is an optical assembly for optical aperture expansion. The apparatus combines diffraction techniques (diffractive components) and facet reflection techniques (reflective components). An innovative embodiment using diffractive components uses at least two components having opposing optical powers (matching), so that the wavelength dispersion introduced by the first diffractive component is subsequently canceled out by the second diffractive component. The two diffractive components are used in combination with reflective optics (for near-eye displays) to achieve more effective aperture expansion, reduce distortion and noise, and also reduce design constraints in the system and individual components compared to conventional techniques.

[0035] Current conventional optical aperture expansion employs a single technique for both lateral and vertical expansion. Current advances in this field involve optimizing and improving one of these techniques. The two main techniques used are as follows: 1) Reflection by a tilted coated facet (e.g., U.S. Patent No. 7,457,040 to Lumus, Ltd.). This reflection technique has a broad spectrum and can therefore project the entire visible spectrum from a single optical guide. This facet typically performs both partial reflection and transmission of propagating light rays, but for the sake of brevity herein, this technique is generally referred to as being carried out by a “reflective optical component.” This reflection is typically polarization-dependent. 2) Diffraction pattern on an optical guide plane. As is known in the art, a diffraction grating (pattern) reflects or transmits propagating light rays, depending on the structure of the diffraction grating. For the sake of brevity in this specification, this technique is generally referred to as being carried out by "diffraction optical components". This diffraction technique is limited in both spectrum and angle. However, the polarization dependence of this technique is low.

[0036] By using arrays of reflective and diffracting components in various quantities and orders (alternating and vice versa), the need for polarization control is eliminated and / or reduced, while a wider field of view is possible. In addition, since the distortion patterns of the two techniques are uncorrelated, the embodiment was able to reduce heterogeneity compared to the conventional single-technology implementation.

[0037] Generally, an apparatus for optical aperture expansion includes at least one optical guide and a set of three optical components associated with at least one optical guide. The set of three optical components includes a pair of matching diffractive optical components and a reflective optical component. The reflective optical component includes an array of multiple surfaces that are at least partially reflective and parallel to each other. These optical components are configured to cooperate to achieve two-dimensional expansion of outward-coupled light. In other words, these components cooperate to expand inward-coupled light to outward-coupled light. Inward-coupled light is light coupled to at least one optical guide, and its expansion is two-dimensional.

[0038] In the context of this explanation, the term "matching" in relation to diffractive optical components generally refers to substantially identical gratings and / or spacings of grating elements, and therefore the optical powers of diffractive components are equivalent and usually contradictory. While the overall physical dimensions of the components may differ, similar gratings will result in matching optical powers for the components.

[0039] In the context of this description, the term "component" is used for optical elements, particularly reflective and diffractive optical elements. Design and production techniques for reflective components and optical parts are known in the art. Based on this description, components can be implemented as required in various shapes and sizes of reflective and diffractive optical parts, with various operating parameters including wavelength, power, and angle.

[0040] In the context of this description, diffractive optical components, also referred to as "diffraction gratings" and "diffraction patterns," may be embedded in an optical guide, configured on the surface of the optical guide, or mounted on it. For example, diffractive optical components can be implemented as diffraction gratings or holographic elements. Diffraction components are available from companies such as Horiba Scientific (Kyoto, Japan), while reflection components are available from companies such as Lumus (Ness Ziona, Israel) with their OE50.

[0041] Referring here to Figures 8A and 8B, rough schematic diagrams of a side view and a front view, respectively, of a typical embodiment of diffraction-reflection-diffraction. Different combinations of optical components magnify light along different axes. The optical light guide (10) is a two-dimensional (2D) light guide with an extension direction arbitrarily illustrated herein to correspond to the "X-axis". The light guide (10) is referred to as a 2D waveguide in the sense that the light guide (10) guides the injected image in two dimensions by reflection between two sets of parallel planes, as shown in Figure 8A by four arrows inside the light guide (10). An array of multiple internal partial reflecting surfaces (40) at an oblique angle (i.e., neither parallel nor perpendicular) to the extension direction and at least partially traverses the light guide (10).

[0042] The incident light (38) is coupled to the optical guide (10) by the diffraction component (5). The internally coupled light enters the optical guide (10), which acts as a first side optical guide expander in a first direction. From the optical guide (10), the expanding light (38C) is coupled to the optical guide (2000). The optical guide (2000) guides the light mainly along the "Y axis". The expanding light (38C) continues to reflect within the optical guide (2000), which expands in a second expansion direction (Y axis), as indicated by the arrow in the side view of Figure 8A. The light in the optical guide (2000) is referred to in this context of this specification as the second expanding light (38D). When the second expanding light (38D) encounters the diffraction pattern (25), it externally couples the optical guide (2000) to the observer (47) (38B). A key feature of this embodiment is that the diffraction components are not parallel to each other.

[0043] Typically, a set of three optical components includes a first optical component (diffraction component (5)) configured to direct internally coupled light (38) in a first magnification direction (X-axis) within a first optical guide (optical guide (10)), thereby generating a first magnified light (38C). A second optical component of the set (arrangement of partial reflectors (40)) is configured to couple the first magnified light (38C) to a second optical guide (2000) in a second magnification direction (Y-axis), thereby generating a second magnified light (38D). A third optical component of the set (diffraction component (25)) is configured to couple the second magnified light (38D) in a third direction as externally coupled light (38B).

[0044] In the context of this description, the term “direction” typically refers to the average direction of propagation within the optical guide, usually along the optical axis (usually the length) of the optical guide. In other words, it is the course or usual path that light captured in the optical guide slab by total internal reflection (TIR) ​​travels along the optical guide slab, i.e., the course of expansion in the plane of the optical guide slab (the in-plane component of the light ray propagating within the substrate of the optical guide).

[0045] The first, second, and third directions are not parallel to each other.

[0046] Referring here to Figure 8D, a diagram of the diffraction directions of light propagating in angular regions (angular intervals) is shown in Figures 8A and 8B. The dotted and solid lines represent two different exemplary wavelengths. The directional region (1005) is the angle of incidence, as described with respect to Figure 7B. Region (1007) represents the direction of the ray (or simply "ray") after lateral expansion and reflection by the array of partial reflectors (40). The partial reflectors (40) redirect the direction of the ray to region (1011). However, this reflection from region (1007) to region (1011) does not introduce extra dispersion and only reflects the direction of propagation around the mirror direction (shown as the dashed line (1008)). The mirror direction (1008) is determined by the inclination of the partial reflectors (40). The last diffracting element (25) diffracts the ray to region (1013). When the light rays are diffracted to the diffracting component (5) in a compensatory manner, the output direction (1013) does not subsequently disperse, but (1005) does not need to be overlapped. In this embodiment, dispersion is eliminated, but the output angle of the externally coupled light (38B) does not have to match the input angle of the internally coupled light (38).

[0047] Referring here to Figure 8C, a rough schematic diagram of a typical reflection-diffraction embodiment is shown. This figure is similar to Figures 8A and B, except that the incident light (38) is coupled to the optical guide (10) by a tilted prism (7) (instead of the diffraction component (5)). Because this embodiment includes only one diffraction element (diffraction element (25)), the chromatic dispersion is significantly greater compared to embodiments of Figures 8A and B, which include two matching diffraction elements ((5) and (25)). Chromatic dispersion (aberration) can be reduced by using a narrowband light source.

[0048] Referring here to Figures 9A and 9B, rough schematic side and front views, respectively, of a typical embodiment of diffraction-diffraction-reflection. The optical guide (2010) is a 2D optical guide. In this embodiment, the first optical component of the set is implemented by a diffraction component (5A) configured to direct internally coupled light (38) in a first magnification direction (X-axis) within the optical guide (2010), thereby generating a first magnified light (38C). The second optical component of the set is implemented by a diffraction component (370) configured to couple the first magnified light (38C) to the optical guide (20) in a second magnification direction (Y-axis), thereby generating a second magnified light (38D). The third optical component of the set is implemented by an array of partial reflective surfaces (facets) (45) which are at least partially traversing the optical guide (20) at an angle to the plane of the optical guide (20), and which are configured to externally connect the second expanding light (38D) in a third direction as externally connected light (38B).

[0049] Referring here to Figure 9C, a diagram of the diffraction direction of light propagating in the angular region (angular interval) is shown in Figures 9A and B. The angular vectors are also shown, where (1005) is the entry direction and (1007) is the direction after the first element (5A). The diffracting element (370) has opposing optical power, and therefore the light is coupled from the optical guide (2010) to the optical guide (20) which has the same direction but no chromatic dispersion (overlap (1005)). Facet (45) reflects the light without dispersion in the preferred direction (1013) where there is no chromatic dispersion. Some chromatic dispersion may be introduced by the reflective component, and the remaining diffraction can compensate for this.

[0050] Referring here to Figures 10A and 10B, rough schematic diagrams of a side view and a front view, respectively, of a typical embodiment of diffraction-reflection. The optical guide (2011) is a 2D optical guide. Lateral expansion is performed by the diffraction component, while vertical expansion is performed by the reflection facet. The method of coupling to the optical guide (2011) is not shown. Light propagates within the optical guide (2011), strikes the diffraction surface (component) (35), and is diffracted toward the optical guide (20). The diffraction component (35) can be on any surface of the optical guide (2011) (shown at the top in this figure). As the light propagates within the optical guide (20), it is outwardly coupled toward the eye (47) by the facet (45) (38B). This configuration does not require polarization control between the optical guide (2011) and the optical guide (20). The injected polarization of the light can be oriented to match what the facet (45) requires.

[0051] Referring here to Figures 11A and 11B, rough schematic diagrams of a typical embodiment of diffraction-diffraction-reflection are shown in side and front views, respectively. A non-diffraction optical component (501) is configured to direct light to an optical guide (2002) as internally coupled light, indicated as light (38). In this embodiment, a single optical guide (2002) is used, and two diffraction components are implemented as parts of the optical guide (2002). The first diffraction optical component (502) is configured to direct internally coupled light (38) in a first expansion direction (X-axis) within one optical guide (2002), thereby generating a first expanded light (38C). The second diffraction optical component (50) is configured to expand the first expanded light (38C) in one optical guide (2002) in a second expansion direction (Y-axis), thereby generating a second expanded light (38D). The reflective optical component (an array of multiple facets (45)) is configured to externally connect a second expanding light (38D) in a third direction as an externally connected light (38B). As in the above embodiment, the first, second, and third directions are not parallel to each other.

[0052] A key feature of this embodiment is the use of a single one-dimensional optical guide. Connection to the optical guide is by a non-diffractive component (501), and the light is transformed by a strong diffraction pattern (502). The light is guided in one dimension and therefore propagates from left to right along the diffraction component (50), expanding in another dimension. When the light encounters the diffraction pattern (50), it is also transformed downward. While propagating downward, the light is reflected towards the observer (47) by a reflective facet (45) (shown in the side view of Figure 11A). This configuration includes a single optical guide and does not require polarization control (the polarization of the light injected into the optical guide may be appropriate for the reflective facet (45)). The combination of diffraction patterns (502) and (50) does not result in chromatic dispersion.

[0053] Referring here to Figure 11C, a rough schematic front view of a typical embodiment of overlapping diffraction-reflection-diffraction is shown. By different techniques, the diffraction and reflection elements can be positioned overlapping each other on the same optical guide. In this figure, the diffraction grating component (1110) magnifies the light (38) that is internally coupled in the first direction to produce a first magnified beam (38C). Lateral aperture magnification is achieved by overlapping diagonal facets (1114) that couple the light laterally front and back, thereby magnifying the light in a second direction (38D) without introducing chromatic aberration. The diffraction pattern (1112) is used to couple the light from the waveguide.

[0054] Referring here to Figures 12A and 12B, rough schematic diagrams of a side view and a front view, respectively, of an exemplary embodiment of diffraction-reflection. Lateral magnification is based on a one-dimensional optical guide (2012) (see, for example, U.S. Patent No. 7,643,214 of Lumus Ltd.). In Figure 12B, coupling to the optical guide (2012) is performed by a highly reflective (i.e., partially reflective and reflecting most of the energy) internal facet (65), which reflects most of the internally coupled light (38) to the left and right sides of the optical guide (2012), while some of the internally coupled light (38) passes through the internal facet (65) to the optical guide (20). When this embodiment includes only one diffracting element, chromatic dispersion becomes important compared to the embodiment in Figure 12C below. Chromatic dispersion (aberration) can be reduced by using a narrowband light source.

[0055] Referring now to Figure 12C, a rough schematic front view of an exemplary embodiment of diffraction-diffraction-reflection is shown. In this embodiment, coupling to the optical guide (2013) is performed by a high-performance diffraction component (66), which reflects most of the internally coupled light (38) to the left and right sides of the optical guide (2013), while some of the internally coupled light (38) passes through the diffraction component (66) to the optical guide (20).

[0056] Similar to the explanation in Figure 9B, the first expanding beam (38C) is diffracted by the diffraction component (67) in Figure 12B and by the diffraction component (68) in Figure 12C, generating a second expanding beam (38D) in the optical guide (20).

[0057] As can be seen from the exemplary embodiments, the diffraction component can generally be positioned on any side of the optical guide. As in the previous embodiments, with appropriate polarization injection, no further instrument-specific adjustments are required.

[0058] Different wavelengths of light are deflected by diffraction patterns in different directions. This phenomenon can be utilized, for example, by implementing separate optical guides for each wavelength in a near-eye display. An exemplary embodiment consists of three optical guides, one for each wavelength corresponding to red (R), green (G), and blue (B) colored light. Individual diffracting side aperture expanders (one for each color) are coupled to a single vertical reflection aperture expander.

[0059] Referring here to Figures 13A and 13B, rough schematic side and front views, respectively, of an exemplary embodiment of diffraction-diffraction-reflection with separate diffraction side expanders are shown. This embodiment is based on the embodiment described above with respect to Figures 9A and 9B. The optical guide (2010) in Figure 9B is replaced with a set of optical guides (103), (102), and (101). Each set of optical guides has a first diffraction component ((133R), (133G), and (133B) respectively) configured for specific wavelengths in red, green, and blue in this example. Each set of optical guides has a second diffraction component ((134R), (134G), and (134B) respectively) that matches the first diffraction component. The internally coupled light (38) is injected through the first diffraction component. Each of these first diffraction components is wavelength-specific, diffracting a specific associated wavelength of light while allowing other wavelengths of light to pass through. Specific diffraction to each optical guide of a wavelength can be improved by adding a set of dichroic reflectors ((133R1), (133G1), (133B1) respectively) after each of the first diffraction components (133R), (133G), and (133B). The dichroic reflectors can be based on coated reflectors or diffraction reflectors, so that different wavelengths are coupled to different respective optical guides (103), (102), and (101). The wavelengths of light diffracted by the first diffraction components (133R), (133G), and (133B) are laterally amplified and propagated in the respective optical guides (103), (102), and (101) as the respective first amplified rays (38CR), (38CG), and (38CB). Each optical guide (103), (102), and (101) has its own second diffraction component (134R), (134G), and (134B), which diffract the respective first amplified rays (38CR), (38CG), and (38CB) toward the optical guide (20).Because the second diffraction components (134G), (134B) are wavelength-selective or have low diffraction efficiency for other wavelengths, light from the upper optical guide passes through the lower optical guide where distortion is least. In the optical guide (20), the array of multiple partial reflectors (45) reflects all wavelengths to the eye (47).

[0060] An alternative description of this embodiment is that a pair of first (133R) and second (134R) corresponding diffractive optical components is increased by 1) a pair of third (133G) and fourth (134G) corresponding diffractive optical components, and 2) a pair of fifth (133B) and sixth (134B) corresponding diffractive optical components. The diffraction spacing of each of the corresponding pairs of optical components is different from that of other corresponding pairs of optical components. The diffraction spacing is such that each of the corresponding pairs of optical components deflects different wavelengths by a similar angle from other corresponding pairs of optical components. The first optical guide (103) includes a pair of first (133R) and second (134R) corresponding diffractive optical components. The second optical guide (103) includes a pair of fourth (133G) and fourth (134G) corresponding diffractive optical components. The third optical guide (103) includes a pair of matching fifth (133B) and sixth (134B) diffractive optical components.

[0061] In this configuration, one optical guide may be in front of the eye (47), and the polarization between optical guides (103), (102), (101), and (20) cannot be arbitrarily controlled. In this configuration, the optical guides may be placed directly above each other (typically, gaps are used between the optical guides to maintain TIR).

[0062] Referring here to Figures 14A and 14B, rough schematic diagrams of the side and front views, respectively, of an exemplary embodiment of diffraction-reflection. This embodiment is similar to the operation described with respect to Figures 12A and 12B, except that the optical guide (2012) is replaced / increased (replaced with three optical guides (160R), (160G), and (160B)). The internal coupling of light (38) to each optical guide (160R), (160G), and (160B) is by their respective, highly reflective internal facets / central splitting mirrors (165R), (165G), and (165B). Lateral (lateral) expansion is diffracted at each optical guide (160R), (160G), (160B), and the first expanding light (38C) is then diffracted / converted to the optical guide (20) to connect outward to the user's eye (47).

[0063] Referring here to Figure 14C, a rough schematic front view of an exemplary embodiment of diffraction-diffraction-reflection is shown. This embodiment is similar to the operation described with respect to Figure 12C, where the diffraction component (66) is replaced / enhanced by a set of diffraction components (133R), (133G), (133B), and dichromatic reflectors ((133R1), (133G1), (133B1), respectively) are linked behind the first diffraction components (133R), (133G), (133B) at the center of each of the respective optical guides (159R), (159G), (159B). Matching diffracting elements (134R), (134G), and (134B) can be replaced by multiple diffracting elements (134R1), (134R2), (134G1), (134G2), (134B1), and (134B2) located on one side of the central diffracting component (133R), (133G), or (133B).

[0064] Referring here to Figures 15A, 15B, and 15C, rough schematic diagrams of the side, front, and top views, respectively, of an exemplary embodiment of diffraction-reflection-reflection. In this embodiment, the reflective aperture expander is located in front of the diffracting expander. Four optical guides are used, which are a reflective component (201) and three diffracting components (205), (206), and (207). The reflective component (201) is an optical guide that expands the reflection laterally. This reflective optical guide (201) may be a 1D optical guide (similar to optical guide (20) in Figure 4A) or a 2D optical guide (similar to optical guide (10) in Figure 8C). The light coupled to the reflective optical guide (201) includes all wavelengths of the coupled light (38), and therefore the reflective optical guide (201) may include a reflector (such as the reflective surface (16) in Figure 4A) or a prism (such as the tilted prism (7) in Figure 8C).

[0065] Facet (203) (depicted in Figure 15C in the plan view) directs the guided light forward and redirects it from optical guide (201) to optical guides (205), (206), and (207). Each of the optical guides (205), (206), and (207) has its own internally linked grating (209R), (209G), and (209B). These internally linked gratings (209R), (209G), and (209B) have different periods for each optical guide, and therefore different wavelengths will be linked by their respective internally linked gratings to their respective associated optical guides.

[0066] Light propagates within the optical guides (205), (206), and (207) and is externally connected (38B) towards the observer (47) by the respective gratings (25R), (25G), and (25B), which are designed according to the wavelength within each optical guide and matched to the respective internally connected gratings (209R), (209G), and (209B).

[0067] Generally, the reflective optical component (facet (203)) is configured to expand the internally coupled light (38) in a first direction of expansion within the first optical guide (201), thereby generating the first expanded light (38C). The first diffractive optical component (209R), the third diffractive optical component (209G), and the fourth diffractive optical component (209B) are configured to couple the respective wavelengths of the first expanded light in the first optical guide (205), the second optical guide (206), and the third optical guide (207), respectively. The second diffractive optical component (25R), the fourth diffractive optical component (25G), and the sixth diffractive optical component (25B) are configured to expand and couple their respective light in a third direction as externally coupled light (38B).

[0068] Referring here to Figure 15D, diagrams of the diffraction directions of light propagating within an angular region (angular interval) are shown in Figures 15A, 15B, and 15C. The front view of the angular direction of a single optical guide shown in Figures 15A-15C is shown in Figure 15D. The light is coupled in direction (1005), and the reflective mirror (203) converts the ray to direction (1007) without dispersion. One of the diffraction coupling components ((209R), (209G), (209B)) converts the ray downward while dispersing it, while the diffraction component (one of the gratings (25R), (25G), (25B)) has opposing optical power, and therefore the light is coupled in the overlapping direction (1007) without dispersion.

[0069] This configuration has strong antidispersive properties and can therefore be used with a small number of components to transmit one or more color channels (R, G, B) in a narrow field (angular spectrum). For example, three optical guides (205), (206), and (207) can be implemented as a single optical guide, or a combination of two color channels can be implemented in a single optical guide (such as a set of {red and green, blue} or {red, green, and blue}).

[0070] It should be noted that the examples, symbols, and illustrative calculations described above are for the purpose of illustrating this embodiment. Careless typographical errors, mathematical inaccuracies, and / or simplified calculations will not impair the usefulness and fundamental advantages of the present invention.

[0071] The fact that the attached claims were drafted without multiple dependencies is simply to comply with formal requirements in legal jurisdictions that do not permit such multiple dependencies. It should be noted that any combination of features that would be implied by making the claims compound dependent should be explicitly assumed and considered as part of the invention.

[0072] The above description is provided for illustrative purposes 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. A device for optical aperture magnification: (a) at least one optical guide; (b) A set of three optical components associated with at least one optical guide, (i) a pair of first and second matching diffractive optical components; and (ii) A set of three optical components, each containing a reflective optical component comprising an array of mutually parallel surfaces that partially reflect; and (c) Includes optical components that cooperate to amplify internally coupled light into externally coupled light, (i) The internally connected light is light connected to the at least one light guide, and (ii) A device in which the magnification is two-dimensional.

2. (a) The first optical component of the set is configured to direct the internally connected light in a first direction of magnification within the first optical guide, thereby generating a first magnified light; (b) The second optical component of the set is configured to connect the first magnified light to a second optical guide in a second direction of magnification, thereby generating the second magnified light; and (c) The third optical component of the set is configured to externally connect the second magnified light as the externally connected light in a third direction; (d) The apparatus according to claim 1, wherein the first, second and third directions are not parallel to each other.

3. (a) further comprising a non-diffractive optical component configured to direct light as internally connected light toward the at least one optical guide; (b) Here, the at least one optical guide is one optical guide, and the one optical guide is (i) A first diffractive optical component configured to direct the internally connected light in a first direction of magnification within one optical guide, thereby generating a first magnified light; (ii) A second diffractive optical component configured to amplify the first amplified light in one optical guide in a second direction of augmentation, thereby generating a second augmented light; and (iii) Includes a reflective optical component configured to externally connect the second amplified light as the externally connected light in a third direction; (iv) The apparatus according to claim 1, wherein the first, second and third directions are not parallel to each other.

4. (i) a pair of third and fourth matching diffractive optical components; and (ii) The apparatus according to claim 1, further comprising a pair of matching fifth and sixth diffractive optical components.

5. The apparatus according to claim 4, wherein each of the matching pairs of diffractive optical components has a different diffraction interval than the other matching pair of diffractive optical components, the diffraction interval being such that each of the matching pairs of diffractive optical components deflects different wavelengths by a similar angle from the other matching pair of diffractive optical components.

6. The apparatus according to claim 5, wherein the wavelengths are red, green, and blue light.

7. (a) The first optical guide of the at least one optical guide includes the pair of first and second matching diffractive optical components; (b) The second optical guide of the at least one optical guide includes the pair of third and fourth matching diffractive optical components; and (c) The apparatus according to claim 5, wherein the third optical guide of the at least one optical guide includes the pair of matching fifth and sixth diffractive optical components.

8. (a) The reflective optical component is configured to amplify the internally connected light in a first direction of magnification within the first optical guide, thereby generating a first magnified light; (b) The first, third, and fourth diffractive optical components are configured to amplify the respective wavelengths of the first amplified light in the first, second, and third optical guides in the second direction of augmentation, thereby generating the respective second augmented light; and (c) The second, fourth, and sixth diffractive optical components are configured to externally connect the respective second amplified light as the externally connected light in the third direction; (d) The apparatus according to claim 7, wherein the first, second and third directions are not parallel to each other.

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