KR102338472B1 - light guide optical assembly - Google Patents

Abstract

The optical assembly for optical aperture expansion combines faceted reflection technology with diffractive technology. At least two components with opposite light outputs (matching) are used so that the chromatic dispersion introduced by the first diffractive component will be canceled out by the second diffractive component. Two diffractive components are used in combination with reflective optical components to achieve more efficient aperture expansion (for near-eye displays) while reducing design constraints on the system and individual components compared to the prior art, resulting in distortion and noise reduces the This assembly eliminates and/or reduces the need for polarization management while providing a wider field of view. Furthermore, in the embodiment, since the distortion patterns of the two techniques are not correlated, the non-uniformity can be reduced compared to the conventional single technique implementation.

Description

light guide optical assembly

FIELD OF THE INVENTION The present invention relates generally to optical assemblies, and more particularly to optical aperture expansion.

BACKGROUND OF THE INVENTION - Fig. 7a to degree 7b

Referring to FIG. 7A , a schematic diagram of a conventional optical aperture expansion using diffractive components within a waveguide is shown. In this figure, the incident light (image) is in the vertical direction entering from the outside of the drawing page (page). A couple-in element 1001 couples the incident light to a lateral extension element 1002 , which expands the light laterally (left to right in the figure). The laterally expanded light is then coupled to a vertically expanding element 1003, which vertically expands the light (top to bottom in the figure) and couples-out the light to the user (viewer's eye). )do.

Conventional diffractive elements cause chromatic dispersion, in which light rays having different wavelengths are diffracted at different angles. A narrow band light source (such as a laser) may be used to reduce chromatic dispersion. A more practical solution is to design the diffractive components to cancel each other's dispersion.

Referring to FIG. 7B , it is a diagram of FIG. 7A in which the diffraction direction of light propagates in an angular domain (angular space). The dashed and solid arrows indicate two different exemplary wavelengths. The starting angle in region 1005 represents the angle of the ray at which the ray reaches the first diffractive element (inwardly coupled element 1001 ) and leads to the light guide. Region 1007 indicates the direction of the ray after coupling element 1001 , region 1009 indicates after lateral extension element 1002 , and region 1005 indicates the direction of the light beam after coupling element 1001 . Shows the angle of the ray after it is connected outward from the guide. In order to minimize chromatic dispersion, the direction of the light rays incident on the light guide is the same as the direction of the light rays leading outward from the light guide. It is clear that lights of different wavelengths will have different directions as they propagate through the light guide, and will have the same direction as they exit the light guide.

Basic technique - Fig. 1 to degree 6

1 shows a conventional foldable optics device, in which a substrate 2 is illuminated by a display source 4 . This display is collimated by means of collimating optics 6 , for example lenses. The light from the display source 4 is connected to the substrate 2 by a first reflective surface 8 such that the main ray 11 is parallel to the substrate surface. A second reflective surface 12 directs light from the substrate and outwardly connects the eye of a viewer 14 . Despite the compactness of this configuration, this configuration has significant drawbacks. In particular, only a very limited FOV can be obtained.

2 , a side view of an exemplary light guide optical element (LOE) is shown. To overcome the above limitations, an array of selectively reflective surfaces can be used and fabricated in a light guide optical element (LOE). The first reflective surface 16 is illuminated by a collimated indicator light (beam) 18 emanating from a light source (not shown) located behind the device. For simplicity, only one ray, incident ray 38 (also referred to as 'beam' or 'incident ray') is schematically illustrated in this figure. Other incident rays, such as beams 18A and 18B, may be used to designate the corners of the incident pupil, such as the left and right corners of the pupil of the incident light. In general, when an image is represented by a beam of light, it is noted that this beam is a sample beam of the image, which is typically formed by multiple beams of slightly different angles, each corresponding to a point or pixel of the image. . The beam shown is typically the center of the image, except when specifically pointing to the end of the image.

The reflective surface 16 reflects the incident light from the source, causing the light to be trapped within the light guide 20 by total internal reflection. The light guide 20 is also referred to as a 'waveguide', a 'planar substrate', and a 'transmissive substrate'. The light guide 20 comprises at least two (major) surfaces parallel to each other, shown in the figure as a rear (major) surface 26 and an anterior (major) surface 26A. The designation of 'front' and 'rear' with respect to major surfaces 26, 26A is for convenience of reference, and light guide 20 is generally symmetrical (thus referring to major surfaces 26, 26A). can be used interchangeably, giving the same result). In the description herein, the light guide 20 is a one-dimensional (1D) waveguide, which guides the injected image only in one dimension between a pair of parallel planes (in this case, the major surfaces 26 and 26A).

Incident ray 38 enters the substrate at the front end of the substrate (right side of the figure). Light propagates along the light guide and generally along at least a plurality of facets and one or more facets, typically a plurality of facets, to the trailing end of the light guide (left side of the figure). Light propagates along the light guide in both an initial propagation direction 28 and another propagation direction 30 .

After being reflected several times from the surface of the substrate 2 , the trapped waves reach an array of selectively reflective surfaces 22 , which outwardly couple the light from the substrate to the viewer's eye 24 . In an alternative configuration, the selective reflective surface 22 is present immediately after the light ray 18 enters the substrate, and there is no first reflection at the surface of the substrate 2 .

Internally partially reflective surfaces, such as selective reflective surface 22, are generally referred to herein as 'facets'. As a limitation, the facet may be either total reflection (100% reflectance or mirror, eg the final facet at the back end of the substrate) or may be minimal-reflection. In augmented reality applications, facets partially reflect light from the real world so that light enters through the upper surface 26A, traverses the substrate containing the facets, and passes the lower surface 26 to the viewer's eye 24 ) to exit. In virtual reality applications, the facet may have an alternative reflectivity, such as a first inwardly connected mirror with 100% reflectivity, so that image light from the real world does not need to traverse this mirror. The inner partially reflective surface 22 generally at least partially traverses the light guide 20 at an oblique angle (ie, not parallel or perpendicular) in the extension direction of the light guide 20 .

References to reflectivity are generally to nominal reflectance. Nominal reflectance is the total reflection required at a particular location on the substrate. For example, if the reflectivity of a facet is 50%, this is generally referred to as a nominal reflectance of 50%. If the nominal reflectivity is 10%, the reflectivity of the facet is 5% if the reflectivity is 50%. Those of ordinary skill in the art will understand to use a fraction of the reflectivity with respect to use. Partial reflection may be implemented by various techniques including, but not limited to, transmission of a portion of light or the use of polarized light.

3A and 3B show the desired reflective behavior of a selective reflective surface. In FIG. 3A , light ray 32 is partially reflected from facet 34 and outwardly connected 38B from substrate 2 . In FIG. 3B , light ray 36 passes through facet 34 without appreciable reflection.

4A is a detailed cross-sectional view illustrating an array of selectively reflective surfaces that direct light inwardly to a substrate and then outward to a viewer's eye. As shown, the light ray 38 from the light source 4 reaches the first partially reflective surface. A portion 41 of the light beam continues in its original direction and connects outwardly from the substrate. Another portion 42 of the light beam is inwardly coupled to the substrate by total internal reflection. The trapped rays are gradually outwardly coupled from the substrate by the other two partially reflective surfaces 22 at points 44 . The coating properties of the first reflective surface 16 need not necessarily be similar to those of the other reflective surfaces 22 , 46 . This coating can be a simple beam-splitter of metallic, dichroic or metallic-dichroic heterotypes. Similarly, in the case of a non-see-through system, the resulting reflective surface 46 may be a simple mirror.

4B is a detailed cross-sectional view of an apparatus comprising an array of reflective surfaces, wherein the final surface 46 is a total reflection mirror. The leftmost portion of the final reflective surface 46 may not be optically valid in this case, and the ray 48 at the periphery may not be coupled outwardly from the substrate. Thus, the output aperture of the device may be slightly smaller. However, the optical efficiency can be higher, and the manufacturing process of the LOE can be simpler.

It is important to note that, unlike the configuration shown in FIG. 2 , there are restrictions on the orientation of the reflective surfaces 16 , 22 . In the former configuration, all light was directed into the substrate by a reflective surface 16 . Accordingly, the reflective surface 16 need not be parallel to the substrate 22 . Further, the reflective surface will be oriented such that the light is directed outwardly from the substrate in a direction opposite to the direction of the incident wavelength. However, in the configuration shown in FIG. 4A , some of the input light is not reflected by the surface 16 , but continues in the original direction of the incident ray 38 and is immediately coupled outward from the substrate as output light 41 . Thus, to ensure that all rays originating from a coplanar wave have the same output direction, not only all reflective surfaces 22 must be parallel to each other, but also reflective surfaces 16 must be parallel to surface 22 .

Referring back to FIG. 4A , a system with two reflective surfaces for outwardly coupling light from a substrate is shown, however any number of reflective surfaces may be used depending on the thickness of the substrate and the output aperture required by the optical system. have. Of course, there are cases where only one outwardly facing connecting surface is required. In this case, the output aperture will essentially be twice the size of the system's input aperture. The reflective surfaces required in the final configuration are simple beam-splitters and mirrors.

In the arrangement shown in the figure, light from the display source is coupled inwardly to the substrate at the ends of the substrate, although there are systems in which it is desirable to have a symmetrical system. That is, the input light must be coupled inwardly to the substrate at the central portion of the substrate.

4C is a view showing a detailed cross-section of a transverse pupil dilated one-dimensional (1D) light guide with a symmetrical structure. This figure shows how to combine two identical substrates to form a symmetrical optical module. As shown, some of the light from the display source 4 exits the substrate directly past the partially reflective surface. Another portion of the light is coupled inwardly to the right side 20R of the substrate and the left side 20L of the substrate by partially reflective surfaces 16R and 16L, respectively. The trapped light is then gradually coupled outward by reflective surfaces 22R and 22L, respectively. Obviously the output aperture is three times the size of the input aperture of the system, the same magnification as shown in Figure 5b. However, unlike the system of Figure 5b, this system is symmetrical with respect to the midplane 29 of the right and left substrates.

5A and 5B, there is shown an exemplary embodiment of FIGS. 4B and 4C on top of a light guide. The configuration of Figures 4b and 4c laterally expands the incident light. The apparatus of FIG. 4B may be used to implement the first LOE 20a of FIG. 5A, the apparatus of FIG. 4C may be used to implement the first LOE 20a' of FIG. 5B, and the apparatus of FIG. 2 may be used to implement the second LOE 20a' of FIG. It can be used to implement LOE 20b.

Figure 5a shows an alternative method of extending the beam along two axes using a dual LOE configuration. The input wave 90 is coupled inwardly by a first reflective surface 16 to a first LOE 20a having an asymmetric structure similar to that shown in FIG. 4b , and then propagates along the η axis. Partially reflective surface 22a couples light outwardly from first LOE 20a, which is then inwardly coupled by reflective surface 16b to second asymmetric LOE 20b. The light then propagates along the ξ axis and is coupled outward by the selective reflective surface 22b. As shown, the original beam 90 expands along both axes, the overall expansion being determined by the ratio between the lateral dimensions of the elements 16a, 22b. The configuration shown in FIG. 5A is only an example of a dual LOE setup. Other configurations are possible in which two or more LOEs are combined together to form a composite optical system.

Referring to FIG. 5B , another method of extending a beam along two axes using a dual LOE configuration is shown. In general, the region where light is connected inwardly 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 need not be transparent. As a result, as can be seen from the drawings, even in the case of a see-through system, the first LOE 20a can be designed to have a generally symmetrical structure. The second LOE 20b has an asymmetric structure, so that the user can see the outside view. In this configuration, a portion 90 of the input beam continues along the original direction 92 to the inwardly connecting mirror 16b of the second LOE 20b, while another portion 94 is on the reflective surface 16a. It is coupled inwardly to the first LOE 20a' by means of which it propagates along the η-axis, and then inwardly connects to the second LOE 20b by means of a selective reflective surface 22a. All parts are then connected inwardly to the second asymmetric LOE 20b by reflective surface 16b, propagating along the ξ axis, and then outwardly connected by selective reflective surface 22b.

6 shows an example of the LOEs 20a/20a', 20b incorporated in the standard eyeglass frame 107. As shown in FIG. The display source 4 and the collimating optical device 6 of the folding type inside the arm part 112 of the eyeglass frame are assembled next to the LOE 20a/20a' located at the edge of the second LOE 20b. have. In the case where the display source is an electronic device such as a CRT, LCD or OLED, the driving electronics 114 of the display source may be assembled in the rear of the arm portion 112 . The power feed and data interface 116 may be connected to the arm 112 by a lead 118 or other communication means, including wireless or optical transmission. Alternatively, a battery and small data link electronics may be included in the frame. This figure is illustrative, and other possible head-mounted display elements may be constructed, including assemblies in which the display source is mounted parallel to or on top of the LOE plane.

Additional details of the underlying technology can be found in US Pat. No. 7,643,214 and PCT/IL2018/050025, which are unpublished and not prior art to the present invention.

In accordance with the teachings of this embodiment, an optical aperture expanding device is provided, comprising: at least one light guide; a set of three optical components associated with the at least one light guide, the set of three optical components including a pair of first and second matching diffractive optical components and a reflective optical element comprising a series of a plurality of partially reflective mutually parallel surfaces; and components working together to expand the inwardly coupled light into outwardly coupled light, wherein the inwardly coupled light is light coupled inwardly to the at least one light guide, and the expansion is two-dimensional.

In an optional embodiment, the first optical component of the set is configured to direct the inwardly coupled light toward a first direction of expansion within the first light guide to generate a first expanded light; a second optical component of the set is configured to inwardly couple the first expanded light in a second direction of extension to a second light guide to generate a second expanded light; a third optical component of the set is configured to outwardly couple the second expanded light as outgoing coupling light in a third direction; The first direction, the second direction and the third direction are not parallel to each other.

In another optional embodiment, further comprising as inwardly coupled light, a non-diffracting optical component configured to direct the light to at least one light guide, wherein the at least one light guide directs the inwardly coupled light within the one light guide. a first diffractive optical component configured to direct in a first extension direction to generate a first expanded light; a second diffractive optical component configured to expand the first expanded light in a second expansion direction within the one light guide to generate a second expanded light; and a reflective optical component configured to outwardly couple the second expanded light in a third direction as outward coupling light, the first direction, the second direction, and the third direction being non-parallel to each other.

In yet another optional embodiment, it further comprises a third and fourth pair of matched diffractive optical components and a fifth and sixth pair of matched diffractive optical components.

In yet another optional embodiment, each optical component of a matching pair has a diffraction space different from the optical component of the other matching pair, wherein in the diffraction space, each optical component of the matching pair is similar to the optical component of the other matching pair. It refracts different wavelengths at an angle.

In yet another optional embodiment, the wavelengths are red light, green light and blue light.

In yet another optional embodiment, the first light guide of the at least one light guide comprises a pair of first and second matched diffractive component optical components; the second light guide of the at least one light guide comprises a pair of third and fourth matched diffractive component optical components; A third light guide of the at least one light guide includes a pair of fifth and sixth matching diffractive component optical components.

In yet another optional embodiment, the reflective optical component is configured to expand the inwardly coupled light in a first direction of extension within the first light guide to produce a first expanded light; The first, third and fourth diffractive optical components extend respective wavelengths of the first expanded light in a second direction of extension within respective first, second and third light guides, such that each second expanded light is configured to create a; the second, fourth and sixth diffractive optical components are configured to outwardly couple each second expanded light as outwardly coupled light in a third direction, the first direction, the second direction, and the third direction being non-parallel to each other not.

Embodiments are described herein with reference to the accompanying drawings by way of example only.
1 is a side view of a conventional foldable optical device;
2 is a side view of an exemplary light guide optical element;
3a and 3b show the desired reflectance and transmittance characteristics of a selective reflective surface for two incident angle ranges;
4A shows an exemplary configuration of a light guide optical element;
Figure 4b is a view showing another configuration of the light guide optical element;
Figure 4c shows a detailed cross-section of a transverse pupil dilatation one-dimensional (1D) light guide with a symmetrical structure;
Figure 5a shows a method of extending a beam along two axes using a dual LOE configuration;
Figure 5b shows another method of extending the beam along two axes using a dual LOE configuration;
6 is a view showing an example of an LOE built into a standard eyeglass frame;
7A is a schematic diagram illustrating conventional optical aperture expansion using diffractive components within a waveguide;
Fig. 7B is a diagram showing the diffraction direction of light propagating in the angular domain in Fig. 7A;
8A and 8B are side and front schematic views, respectively, showing exemplary embodiments of diffraction-reflection-diffraction;
8C is a schematic diagram illustrating an exemplary embodiment of reflection-diffraction;
Fig. 8D is a diagram showing the diffraction direction of light propagating in the angular domain in Figs. 8A and 8B;
9A and 9B are side and front schematic views, respectively, showing an exemplary embodiment of diffraction-diffraction-reflection;
Fig. 9c is a diagram showing the diffraction direction of light propagating in the angular domain in Figs. 9a and 9b;
10A and 10B are side and front schematic views, respectively, showing exemplary embodiments of diffraction-reflection;
11A and 11B are side and front schematic views, respectively, showing an exemplary embodiment of diffraction-diffraction-reflection;
11C is a front schematic diagram illustrating an exemplary embodiment of superposition diffraction-reflection-diffraction;
12A and 12B are side and front schematic views, respectively, showing exemplary embodiments of diffraction-reflection;
12C is a front schematic diagram illustrating an exemplary embodiment of diffraction-diffraction-reflection;
13A and 13B are side and front schematic views showing an exemplary embodiment of diffraction-diffraction-reflection with each individual diffractive lateral dilator;
14A and 14B are side and front schematic views, respectively, showing an exemplary embodiment of diffraction-reflection;
14C is a front schematic diagram illustrating an exemplary embodiment of diffraction-diffraction-reflection;
15A, 15B, and 15C are side, front and top schematic views, respectively, showing exemplary embodiments of reflection-diffraction-diffraction;
Fig. 15D is a diagram showing the diffraction direction of light propagating in the angular domain in Figs. 15A, 15B and 15C.

Abbreviations and definitions

For convenience of reference, this paragraph presents a brief list of abbreviations, acronyms, and short definitions used in this document. This paragraph is not meant to be limiting. A more detailed description can be found below and in the applicable standards.

1D - 1D

2D - 2D

CRT - cathode ray tube

EMB - eye-motion-box

FOV - field-of-view

HMD - head-mounted display

HUD - heads-up display

LCD - liquid crystal display

LOE - Light Guide Optical Element

OLED - Organic Light Emitting Diode Array

OPL - optical path length

SLM - Spatial Light Modulator

TIR - Total Internal Reflection

Detailed Description - Figures 8a to 15d

The principle and operation of the apparatus according to the present embodiment will be better understood with reference to the drawings and the accompanying detailed description. The present invention is an optical assembly for optical aperture expansion. The device combines faceted reflection technology (reflective component) with diffractive technology (diffractive component). A groundbreaking embodiment that utilizes a diffractive component uses at least two components with opposite light outputs (matching) such that the chromatic dispersion introduced by the first diffractive component is canceled by the second diffractive component. By using two diffractive components in combination with a reflective optical component, more efficient aperture expansion (for near eye displays) while reducing design constraints on the system and individual components compared to prior art to reduce distortion and noise.

Currently, conventional optical aperture expansion uses one technique for both expansions (lateral and vertical). Current advances in the art are to optimize and improve either of these technologies. The two main techniques used are:

1) Reflection by oblique coated facets (eg, US Pat. No. 7,457,040 to Lumus). This reflective technology has a broad spectrum and can project the entire visible spectrum from a single light guide. Although facets perform both partial reflection and transmission of propagating light, in this specification, for the sake of simplicity, this technique is generally assumed to be implemented by a 'reflective optical component'. Reflection is typically dependent on polarization.

2) Diffraction pattern on the light guide face. As is known, a diffraction grating (pattern) can reflect or transmit a propagating light beam depending on the structure of the grating. In this specification, for the sake of simplicity, it is assumed that this technique is generally implemented by a 'diffractive optical component'. This diffraction technique is limited in both spectrum and angle. However, this technique has low polarization dependence.

By using a series of reflective and diffractive components, the need for polarization management is eliminated and/or reduced in varying degrees and order (in turn or vice versa) while making the field of view wider. Furthermore, in the embodiment, since the distortion patterns of the two techniques are not correlated, the non-uniformity can be reduced compared to the conventional single technique implementation.

Generally, an apparatus for expanding an optical aperture comprises at least one light guide and a set of three optical components associated with the at least one light guide. The set of three optical components includes a pair of matching diffractive optical components and one reflective optical component. The reflective optical component includes a series of a plurality of at least partially reflective mutually parallel surfaces. The optical components are configured to work together to achieve a two-dimensional expansion of outwardly coupled light. In other words, the components work together to expand inwardly coupled light into outwardly coupled light. Inwardly coupled light is light that couples inwardly into at least one light guide, and the extension is two-dimensional.

In the context of this description, the term 'matching' in relation to diffractive optical components generally refers to substantially exactly the same grating and/or spacing of grating elements such that the optical power of the diffractive components is equal and typically opposite. Although the overall physical dimensions of the components are different, the light output of the components is matched because the gratings are similar.

In the context of this description, the term “component” is used with respect to optical elements, in particular reflective and diffractive optical elements. Techniques for the design and production of reflective and diffractive optical components are known. Based on the present description, components may be implemented according to needs in various shapes and sizes of reflective and diffractive optical components with various operating parameters including wavelength, power, and angle.

In the context of this description, diffractive optical components referred to as 'diffraction gratings' and 'diffraction patterns' may be embedded within the light guide or may be constructed or mounted to a surface (plane) of the light guide. For example, the diffractive optical component may be implemented as a diffraction grating or holographic element. The diffractive component is available from Horiba Scientific (Kyoto, Japan) and the like, and the reflective component is available from OE50 and the like of Lumus (Nesgiona, Israel).

8A and 8B, there are shown side and front schematic views, respectively, representing exemplary embodiments of diffraction-reflection-diffraction. Different optical components are combined to expand the light along various axes. The optical light guide 10 is a two-dimensional light guide with an extension direction arbitrarily shown herein as corresponding to the “x-axis”. In the sense that the light guide 10 guides the injected image in two dimensions by reflection between two parallel planes, as shown by the four arrows in the light guide 10 in FIG. 8A , the light guide ( 10) refers to the 2D waveguide. A series of plurality of inner partially reflective surfaces 40 within at least partially transverse light guide 10 are angled (ie, neither parallel nor perpendicular) with respect to the direction of extension.

The incident ray 38 is connected inwardly to the light guide by a diffractive component 5 . The inwardly coupled light enters the light guide 10 serving as a first lateral light guide dilator in a first direction. Light 38C extending from light guide 10 is coupled inwardly to light guide 2000 . Optical light guide 2000 guides light primarily along the “y-axis”. The expanded light 38C continues to be reflected within the light guide 2000 and extends in a second direction of expansion (y-axis) as shown by the arrow in the side view of FIG. 8A . The light in the light guide 2000 is referred to herein as the second expanded light 38D. When the second expanded light 38D arrives at the diffraction pattern 25 , the second expanded light is coupled outwardly from the light guide 2000 to the viewer 47 ( 38B ). A characteristic of this embodiment is that the diffractive components are not parallel to each other.

In general, the set of three optical components directs the inwardly connecting light 38 to a first light guide (a first direction of extension (x-axis) within the light guide 10 ) to direct the first expanded light 38C. a first optical component (diffractive component 5) configured to generate. A second optical component of the set (series of partially reflective surfaces 40) directs the first expanded light 38C in a second direction of extension ( y-axis) inwardly into a second light guide 2000 to produce a second expanded light 38D. A third optical component of this set (diffractive component 25) is a second expanded light 38D. configured to outwardly couple light 38D in a third direction as outward coupling light 38B.

In the context of this description, the term 'direction' generally refers to the average direction of propagation within a light guide, typically along the optical axis (usually the length) of the light guide. In other words, the path, or general direction, along which light trapped by total internal reflection (TIR) within a light guide slab travels along the light guide slab is a light guide slab that is an in-plane component of the ray propagating in the substrate of the light guide. is an extension path in the plane of

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

Referring to Fig. 8d, the diffraction direction of light propagating in the angular domain (angular space) is shown in Figs. 8a and 8b. The dashed and solid lines indicate two different exemplary wavelengths. Directional area 1005 is the angle of incidence as described with reference to FIG. 7B . Region 1007 represents the direction of a light ray (or 'ray' for short) after lateral expansion and reflection by a series of partially reflective surfaces 40 . Partially reflective surface 40 redirects the rays of light to area 1011 . However, reflection from region 1007 to region 1011 does not introduce additional dispersion, it only mirrors the propagation direction around the mirror direction (shown by dash-dotted line 1008 ). The mirror direction 1008 is determined by the tilt of the partially reflective surface 40 . The final diffractive element 25 diffracts the light beam into a region 1013 . As the ray is diffracted into the diffractive component 5 in a compensating manner, the output direction 1013 will not be dispersed and will not need to overlap 1005 . In this embodiment, dispersion is eliminated, but the output angle of outgoing coupling light 38B need not match the input angle of inward coupling light 38 .

Referring to FIG. 8C , a reflection-diffraction exemplary embodiment is schematically illustrated. This view is similar to FIGS. 8A and 8B except that the incident light 38 is coupled inwardly to the light guide 10 by a tilting prism 7 (instead of the diffractive component 5 ). Since this embodiment contains only one diffractive element (diffractive element 25), the chromatic dispersion will be large compared to the embodiment of Figs. 8a and 8b which contains two matching diffractive elements 5, 25. Chromatic dispersion (aberration) can be reduced by using a narrowband light source.

9A and 9B, respectively, side and front views of a diffraction-diffraction-reflection exemplary embodiment are shown. The light guide 2010 is a 2D light guide. In the present embodiment, the first optical component of the set is configured such that the inwardly coupled light 38 is directed in a first direction of extension (x-axis) within the light guide 2010 , thereby generating a first expanded light 38C. implemented by the configured diffractive component 5A. A second optical component of the set is a diffractive component configured to inwardly couple the first expanded light 38C in a second direction of extension (y-axis) to the light guide 20 to produce a second expanded light 38D. (370). The third optical component of this set is an outward coupling light of the second expanded light 38D by a series of a plurality of partially reflective surfaces (facets) 45 , preferably at least partially traversing light guide 20 . 38B, at an oblique angle with respect to the face of the light guide 20 configured to connect outwardly in the third direction.

Referring to Fig. 9C, the diffraction direction of light propagating in the angular domain (angular space) is shown in Figs. 9A and 9B. The angle vector is shown, where 1005 is the direction of incidence and the direction after the first element 5A is 1007. Since diffractive element 370 has opposite optical power, light will be coupled inwardly from light guide 2010 to light guide 20 with the same direction but no chromatic dispersion (overlapping 1005). Facet 45 reflects light in desired direction 1013 without chromatic dispersion. Some chromatic dispersion is introduced by the reflective component, and the remaining diffraction can compensate for this.

Referring to FIGS. 10A and 10B , side and front schematic views, respectively, of an exemplary embodiment of diffraction-reflection are shown. The light guide 2011 is a 2D light guide. Lateral expansion is achieved by diffractive components, while vertical expansion is achieved by reflective facets. A method of inwardly connecting to the light guide 2011 is not shown. Light propagates within the light guide 2011 , reaches a diffractive surface (component) 35 , and is diffracted towards the light guide 20 . The diffractive component 35 may be present on any surface (shown at the top in the figure) of the light guide 2011 . As the light propagates within the light guide 20 , it is outwardly coupled 38B to the eye 47 by facets 45 . This configuration does not require polarization management between the light guide 2011 and the light guide 20 . The polarization of the injected light may be oriented to match the polarization required for the facet 45 .

11A and 11B, there are shown side and front schematic views, respectively, representing exemplary embodiments of diffraction-diffraction-reflection. Non-diffractive optical component 501 is configured to direct light to light guide 2002 as inwardly coupled light, as indicated by light 38 . In this embodiment, one light guide 2002 is used and two diffractive components are implemented as part of the light guide 2002 . The first diffractive optical component 502 is configured to direct the inwardly coupled light 38 to a first direction of extension (x-axis) within one light guide 2002 to generate a first expanded light 38C. The second diffractive optical component 50 is configured to expand the first expanded light 38C in one light guide 2002 in a second direction of extension (y-axis) to generate a second expanded light 38D. do. The reflective optical component (series of plurality of facets 45 ) is configured to outwardly couple the second expanded light 38D as outward coupling light 38B in a third direction. In the above embodiment, the first, second and third directions are not parallel to each other.

A feature of this embodiment is the use of a single, one-dimensional light guide. Inward coupling to the light guide is by the non-diffractive component 501 , which is diverted by the strong diffraction pattern 502 . This light is guided in one dimension and thus extends in the other dimension while propagating from left to right along the diffractive component 50 . When the light reaches the diffraction pattern 50, it is diverted back down. As it propagates downward, this light is reflected by a reflective facet 45 (shown in side view FIG. 11A ) to an observer 47 . This configuration includes one light guide and does not require polarization management (the polarization of the light injected into the light guide can be adapted to the reflective facet 45). The combination of the diffraction pattern 502 and the diffraction pattern 50 does not cause chromatic dispersion.

Referring to FIG. 11C , it is a front schematic diagram illustrating an exemplary embodiment of superposition diffraction-reflection-diffraction. Due to the different techniques, the diffractive and reflective elements can be placed in an overlapping relationship in the same light guide. In this figure, the diffraction grating component 1110 expands the inwardly coupled light in a first direction to generate a first expanded light 38C. The lateral aperture expansion is implemented by overlapping the diagonal facets 114 that connect the light back and forth laterally, expanding the light in the second direction 38D, and introducing no chromatic aberration. A diffraction pattern 1112 is used to couple the light from the waveguide outward.

12A and 12B are side and front schematic views, respectively, representing exemplary embodiments of diffraction-reflection. Transverse expansion is based on a one-dimensional light guide (2012) (see, eg, US Pat. No. 7,643,214 to Lumus). In FIG. 12B , the inward coupling to the light guide 2012 is a highly reflective (partially reflecting and reflecting most of the energy) inner facet that reflects most of the inwardly coupled light 38 to the left and right of the light guide 2012 . 65 , a portion of the inwardly connecting light 38 goes through the inner facet 65 to the light guide 20 . Since this embodiment includes only one diffractive element, the chromatic dispersion is larger than that of the embodiment of FIG. 12C below. Chromatic dispersion (aberration) can be reduced by using a narrowband light source.

Referring to FIG. 12C , there is shown a front schematic diagram illustrating an exemplary embodiment of diffraction-diffraction-reflection. In this embodiment, the inward coupling to the light guide 2013 is performed by a diffractive component 66 with high efficiency that reflects most of the inwardly coupled light 38 to the left and right sides of the light guide 2013 and , a portion of the inwardly coupled light 38 goes through the diffractive component 66 to the light guide 20 .

Similar to FIG. 9B , the first expanded light 38C is diffracted by the diffractive component 67 in FIG. 12B and by the diffractive component 68 in FIG. 12C , such that the second expanded light within the light guide 20 is (38D).

As can be seen from the exemplary embodiment, the diffractive component may be positioned generally on any side of the light guide. In this embodiment, by injecting the appropriate polarization, no additional maintenance with the device is required.

Different wavelengths of light are refracted in different directions by the rotation pattern. This phenomenon is used, for example, in near-eye displays by implementing a separate light guide for each wavelength. A typical embodiment is three light guides, each wavelength corresponding to red (R), green (G) and blue (B) light. A separate diffractive lateral aperture expander (one for each color) is coupled to one vertical reflection aperture expander.

13A and 13B , side and front schematics are shown illustrating an exemplary embodiment of diffraction-diffraction-reflection with each individual diffractive lateral dilator. This embodiment is based on the embodiment described above with respect to Figures 9a and 9b. In FIG. 9B , light guide 2010 is positioned within a set of light guides 103 , 103 , 101 . Each light guide in this set has a first diffractive component (133R, 133G, 133B, respectively) configured for a particular wavelength (red, green and blue in this example). Each light guide of this set has a second diffractive component (134R, 134G, 134B, respectively) that matches the first diffractive component. The inwardly coupled light 38 is injected through the first diffractive component. Each of these first diffractive components is wavelength dependent, diffracting light of a particular relevant wavelength and passing light of another wavelength. Wavelength dependent diffraction into each light guide may be implemented by adding a set of dichroic reflectors 133R1 , 133G1 , 133B1 after each first diffractive component 133R, 133G, 133B. The dichroic reflector may be based on a coating or a diffractive reflector, with a different wavelength coupled to each different light guide 103 , 102 , 101 . The wavelength of light diffracted by the first diffractive component 133R, 133G, 133B is expanded so as to laterally in the respective light guide 103, 102, 101 as the respective first expanded light 38CR, 38CG, 38CB. is propagated to Each light guide 103 , 102 , 101 has a respective second diffractive component 134R, 134G, 134B that diffracts a respective first expanded light 38CR, 38CG, 38CB toward the light guide 20 . have Light from the upper light guide passes through the lower light guide with minimal distortion because the second diffractive components 134G, 134B are either wavelength selective or have low diffraction efficiency for other wavelengths. In the light guide 20 , a series of a plurality of partially reflective surfaces 45 reflects all wavelengths to the eye 47 .

An alternative description of this embodiment is given in a first and second pair of matched diffractive optical components 133R, 134R, 1) a third and fourth pair of matched diffractive optical components 133G, 134G, and 2) a fifth and A sixth pair of matching diffractive optical components 133B, 134B is added. Each optical component of the matching pair has a different diffraction space than the optical component of the other matching pair. The diffractive space is such that each diffractive component of a matching pair refracts a different wavelength from an optical component of the other matching pair through a similar angle. The first light guide 103 includes first and second matched diffractive optical components 133R, 134R. The second light guide 102 includes a pair of third and fourth matched diffractive optical components 133G, 134G. The third light guide 101 includes a pair of third and fourth matched diffractive optical components 133G, 134G.

In this configuration, one light guide can be in front of the eye 47 , and optionally there is no polarization management between the light guides 103 , 102 , 101 , 20 . In this configuration the light guides can be placed directly on top of each (typically an air gap is used between the light guides to maintain the TIR).

14A and 14B, side and front schematics are shown, respectively, representing exemplary embodiments of diffraction-reflection. This embodiment is similar to the operation described above with reference to FIGS. 12A and 12B , wherein the light guide 2012 is replaced/added (replaced with three light guides 160R, 160G, 160B). The inward coupling of light to the respective light guides 160R, 160G, 160B is by means of the highly reflective inner facet/central split mirrors 165R, 165G and 165B, respectively. The lateral (transverse) extension is diffracted in each light guide 160R, 160G, 160B, and then the first expanded light 38C is diffracted/diffracted to the light guide 20 for outward coupling to the user's eye 47 is converted

Referring to FIG. 14C , there is a front schematic diagram illustrating an exemplary embodiment of diffraction-diffraction-reflection. This embodiment is similar to the operation described with reference to FIG. 12C , wherein the diffractive component 66 is replaced/added by a set of diffractive components 133R, 133G, 133B, each individual light guide 159R, 159G, 159B ), after each first diffractive component 133R, 133G, 133B in the center, is associated with a dichroic reflector (133R1, 133G1, 133B1, respectively). Matching diffractive elements 134R, 134G, 134B are replaced with a plurality of diffractive elements 134R1, 134R2, 134G1, 134G2, 134B1, 134B2 on either side of the central diffractive component 133R, 133G, 133B.

15A, 15B, and 15C are side, front and top schematic views, respectively, representing exemplary embodiments of reflection-diffraction-diffraction. In this embodiment, the reflective aperture expander precedes the diffractive expander. Four light guides: a reflective component 201 and three diffractive components 205 , 206 , 207 are used. The reflective component 201 is a reflective laterally expanding light guide. This reflective light guide 201 may be a 1D light guide (similar to light guide 20 in Fig. 4A) or a 2D light guide (similar to light guide 10 in Fig. 8C). The light that is inwardly coupled to the reflected light guide 201 includes all wavelengths of the inwardly coupled light 38, so the reflected light guide 201 is either a reflector (such as reflective surface 16 in FIG. 4A) or a prism ( such as the inclined prism of Figure 8c).

Facets 203 (shown in FIG. 15C ) direct the guided light towards light guide 201 and divert out of light guide 201 and out therefrom to light guides 205 , 206 , 207 . Each of the light guides 205, 206, 207 has a respective inwardly coupled grating 209R, 209G, 209B. These inwardly coupled gratings 209R, 209G, 209B have different durations for each light guide, so that different wavelengths Each associated light guide is connected by a respective inwardly coupled grating.

Light propagates within light guides 205 , 206 , 207 , with respective gratings 25R, 25G designated according to a wavelength within each light guide and matched to respective inwardly coupled gratings 209R, 209G, 209B, respectively. , 25B) outwardly connected to the observer 47 (38B).

Generally, the reflective optical component (facet 203 ) is configured to expand inwardly coupled light 38 in a first direction of extension within first light guide 201 to produce first expanded light 38C. The first (209R), third (209G) and fourth (209B) diffractive optical components are each of the first expanded light within the respective first ( 205 ), second ( 206 ), and third ( 207 ) light guides. is configured to connect the wavelengths of The second (25R), fourth (25G) and sixth (25B) diffractive optical components are configured to expand and outwardly couple each light as outwardly coupled light 38B in a third direction.

Referring to Fig. 15d, the diffraction direction of light propagating in the angular domain (angular space) is shown in Figs. 15a, 15b and 15c. An angled front view of the single light guide shown in FIGS. 15A-15C is shown in FIG. 15D . The light is coupled inward as direction 1005 , and reflective mirror 203 diverts the light beam in direction 1007 without scattering. The diffractive inward coupling component (one of 209R, 209G, 209B) scatters and diverts the light beam, while the diffractive component (one of 25R, 25G, 25B) has the opposite optical power and thus couples the light outward without scattering (Direction Overlap (1007)).

This configuration has strong anti-dispersion properties, so a reduced number of components can be used to convey one or more color channels (R, G, B) into a narrow field (angle spectrum). For example, three light guides 205 , 206 , 207 may be implemented as a single light guide, or a combination of two color channels may be implemented in a single light guide ({red and green, blue} or {red). , as a set of green and blue }).

It is noted that the above examples, numbers used, and exemplary calculations are for the purpose of assisting in the description of the present embodiment. Unintentional typos, numerical errors, and/or use of simple calculations do not depart from the usefulness and basic advantages of the present invention.

If the appended claims have been drafted without multiple dependent claims, this is done only to meet formal requirements in jurisdictions that do not allow such multiple dependent claims. All possible combinations of features that make up the multiple dependent claims of the claims are expressly contemplated and are to be regarded as part of the invention.

It is to be understood that the above description has been given by way of example, and that many other embodiments defined in the appended claims are possible within the scope of the invention.

Claims (8)

A device for expanding the optical aperture is provided;
(a) at least one light guide comprising a first pair of outer surfaces parallel to each other for guiding light by internal reflection;
(b) a set of three optical components of the at least one light guide,
The set of three optical components is:
(i) a first matching diffractive optical component;
(ii) a reflective optical component comprising a set of facets; and
(iii) a second matching diffractive optical component;
The one set of facets is:
(A) comprising a plurality of partially reflective facets parallel to each other, (B) between the first pair of outer surfaces, (C) non-parallel to the first pair of outer surfaces;
wherein the set of three optical components work together to redirect coupled-in light to coupled-out light;
(i) the inwardly coupled light is inwardly coupled to the at least one light guide;
(ii) the at least one light guide is configured to redirect the inwardly coupled light in two dimensions
Device for optical aperture expansion.
The method of claim 1,
(a) a first matched diffractive optical component of the set is configured to direct the inwardly coupled light to a first direction of extension within a first light guide to produce a first expanded light;
(b) a second matched diffractive optical component of the set is configured to couple the first expanded light to a second light guide in a second expansion direction to produce a second expanded light;
(c) the reflective optical component of the set is configured to outwardly couple the second expanded light as the outwardly coupled light in a third direction;
(d) the first extension direction, the second extension direction and the third direction are not parallel to each other
Device.
The method of claim 1,
(a) the inwardly coupled light, a non-diffractive optical component configured to direct light to the at least one light guide
further comprising,
(b) the at least one light guide comprises:
(i) the first matched diffractive optical component configured to direct the inwardly coupled light in a first direction of extension within the one light guide to produce a first expanded light;
(ii) the second matched diffractive optical component configured to expand the first expanded light in a second direction of expansion within the one light guide to produce a second expanded light;
(iii) the reflective optical component configured to outwardly couple the second expanded light in a third direction as the outwardly coupled light
It is a single light guide comprising a,
(iv) the first direction, the second direction and the third direction are not parallel to each other
Device.
The method of claim 1,
(i) a third and fourth pair of matched diffractive optical components;
(ii) a pair of fifth and sixth matched diffractive optical components
A device further comprising a.
5. The method of claim 4,
each of the optical components of the matching pair has a diffraction space different from the optical component of the other matching pair,
In the diffraction space, each of the optical components of the matching pair refracts a different wavelength than the optical component of another matching pair.
Device.
6. The method of claim 5,
the wavelength is red light, green light and blue light
Device.
6. The method of claim 5,
(a) a first light guide of the at least one light guide comprises a pair of the first and second matched diffractive optical components;
(b) a second light guide of the at least one light guide comprises a pair of the third and fourth matched diffractive optical components;
(c) a third light guide of the at least one light guide comprises a pair of the fifth and sixth matched diffractive optical components;
Device.
8. The method of claim 7,
(a) the reflective optical component is configured to expand the inwardly coupled light in a first direction of extension within a first light guide to produce a first expanded light;
(b) the first, third and fifth matched diffractive optical components extend respective wavelengths of the first expanded light in a second direction of expansion within respective first, second and third light guides, respectively configured to generate a second expanded light of
(c) the second, fourth and sixth matched diffractive optical components are configured to outwardly couple the respective second expanded light as the outwardly coupled light in a third direction;
(d) the first direction, the second direction and the third direction are not parallel to each other
Device.

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