Patent Description:
Near-eye light field displays project images directly into a user's eye, encompassing both near-eye displays (NEDs) and electronic viewfinders. Conventional near-eye displays (NEDs) generally have a display element that generates image light that passes through one or more lenses before reaching the user's eyes. Additionally, NEDs in virtual reality systems and/or augmented reality systems are typically required to be compact and light weight, and to provide large exit pupil with a wide field-of-vision for ease of use. However, designing a conventional NED with a wide field-of -view can result in rather large lenses, and a relatively bulky and heavy NED.

<CIT> describes a projection display which includes first and second waveguide elements, wherein the first waveguide element has two input regions for injecting image bearing light into the first waveguide element. In this manner, the total field of view of the image to be displayed at the second waveguide element is divided into two sub-images prior to injection of one sub-image into one input region and the other sub-image into the other input region of the first waveguide element. This results in a smaller first waveguide element, thereby reducing obscuration of an observers view of a forward scene over which to the image to be displayed is overlaid.

<CIT> describes an optical device comprising: a transparent blade the first surface of which is reflective; a first partially reflective and partially transmissive layer covering a second surface of the transparent blade opposite the first surface, and a second layer covering the surface of the first layer opposite the transparent blade, wherein the second layer is made of a material having an optical index which differs from the optical index of the transparent blade by less than <NUM>% and preferably by less than <NUM>%, and the second layer comprises, on the surface thereof opposite the first layer, structures forming a diffraction grating suitable for promoting the extraction of light towards the outside of the transparent blade.

According to an aspect of the invention, there is provided a waveguide assembly for a waveguide display, the waveguide assembly comprising a source waveguide and an output waveguide, the waveguide assembly being according to claim <NUM>.

In some embodiments, the source waveguide receives the first image light at a first region and the second image light at a second region, the first region and the second region located at an edge of the source waveguide. The first entrance area may include a first coupling element and the second entrance area may include a second coupling element, each of the first coupling element and the second coupling element including grating elements of a grating period selected based on a refractive index of a material forming the source waveguide.

According to another aspect of the invention, there is provided a waveguide display according to claim <NUM>.

Further features according to embodiments of the invention are defined in the dependent claims.

The figures depict embodiments of the present disclosure for purposes of illustration only. One skilled in the art will readily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles, or benefits touted, of the disclosure described herein.

A tiled waveguide display (also referred to as a "waveguide display") is a display that can widen a field of view of image light emitted from the waveguide display. In some embodiments, the waveguide display is incorporated into, e.g., a near-eye-display (NED) as part of an artificial reality system. The waveguide display includes a tiled waveguide assembly and an output waveguide. The tiled waveguide assembly includes a first light source that emits a first image light corresponding to a first portion of an image, a second light source that emits a second image light corresponding to a second portion of the image that is different than the first portion of the image, a source waveguide including a first entrance area, a second entrance area, a first exit area, and a second exit area, and an output waveguide including a third entrance area and a third exit area. Light from each of the first light source and the second light source is coupled into the source waveguide which emits the image light at specific locations along the source waveguide. Each of the first light source and the second light source may project a one-dimensional line image to an infinite viewing distance through a small exit pupil. The one-dimensional line image can be formed by, for example, using a linear array of sources and a collimating lens. The source waveguide includes a plurality of grating elements with a constant period determined based on the conditions for total internal reflection and first order diffraction of the received image light. To form a two-dimensional image, the source waveguide is scanned line-by-line in a direction orthogonal with respect to the one-dimensional line image projected by the first light source and the second light source. The source waveguide may be tiled around an axis of the projected one-dimensional line image to form the two-dimensional image. The emitted image light is coupled into the output waveguide at a plurality of entrance locations. The output waveguide outputs a plurality of expanded image light at a location offset from the entrance location, and the location/direction of the emitted expanded image light is based in part on the orientation of the first light source and the second light source. Each of the plurality of expanded image light is associated with a field of view of the expanded image light emitted by the output waveguide. In some examples, the total field of view of the tiled waveguide display may be a sum of the field of view of each of the expanded image light.

Embodiments of the invention may include or be implemented in conjunction with an artificial reality system. Artificial reality is a form of reality that has been adjusted in some manner before presentation to a user, which may include, e.g., a virtual reality (VR), an augmented reality (AR), a mixed reality (MR), a hybrid reality, or some combination and/or derivatives thereof. Artificial reality content may include completely generated content or generated content combined with captured (e.g., real-world) content. The artificial reality content may include video, audio, haptic feedback, or some combination thereof, and any of which may be presented in a single channel or in multiple channels (such as stereo video that produces a three-dimensional effect to the viewer). Additionally, in some embodiments, artificial reality may also be associated with applications, products, accessories, services, or some combination thereof, that are used to, e.g., create content in an artificial reality and/or are otherwise used in (e.g., perform activities in) an artificial reality. The artificial reality system that provides the artificial reality content may be implemented on various platforms, including a head-mounted display (HMD) connected to a host computer system, a standalone HMD, a mobile device or computing system, or any other hardware platform capable of providing artificial reality content to one or more viewers.

Embodiments of the invention may include or be implemented in conjunction with an artificial reality system. Artificial reality is a form of reality that has been adjusted in some manner before presentation to a user, which may include, e.g., a virtual reality (VR), an augmented reality (AR), a mixed reality (MR), a hybrid reality, or some combination and/or derivatives thereof. Artificial reality content may include completely generated content or generated content combined with captured (e.g., real-world) content. The artificial reality content may include video, audio, haptic feedback, or some combination thereof, and any of which may be presented in a single channel or in multiple channels (such as stereo video that produces a three-dimensional effect to the viewer). Additionally, in some embodiments, artificial reality may also be associated with applications, products, accessories, services, or some combination thereof, that are used to, e.g., create content in an artificial reality and/or are otherwise used in (e.g., perform activities in) an artificial reality. The artificial reality system that provides the artificial reality content may be implemented on various platforms, including a HMD connected to a host computer system, a standalone HMD, a mobile device or computing system, or any other hardware platform capable of providing artificial reality content to one or more viewers.

<FIG> is a diagram of a near-eye-display (NED) <NUM>, in accordance with an embodiment. The NED <NUM> presents media to a user. Examples of media presented by the NED <NUM> include one or more images, video, audio, or some combination thereof. In some embodiments, audio is presented via an external device (e.g., speakers and/or headphones) that receives audio information from the NED <NUM>, a console (not shown), or both, and presents audio data based on the audio information. The NED <NUM> is generally configured to operate as an artificial reality NED. In some embodiments, the NED <NUM> may augment views of a physical, real-world environment with computer-generated elements (e.g., images, video, sound, etc.).

The NED <NUM> shown in <FIG> includes a frame <NUM> and a display <NUM>. The frame <NUM> is coupled to one or more optical elements which together display media to users. In some embodiments, the frame <NUM> may represent a frame of eye-wear glasses. The display <NUM> is configured for users to see the content presented by the NED <NUM>. As discussed below in conjunction with <FIG>, the display <NUM> includes at least one waveguide display assembly (not shown) for directing one or more image light to an eye of the user. The waveguide display assembly includes at least one or more tiled waveguide displays. The waveguide display assembly may also include, e.g., a stacked waveguide display, a varifocal waveguide display, or some combination thereof. The tiled waveguide display is a display that can widen a field of view of the image light emitted from the waveguide display. The varifocal waveguide display is a display that can adjust a depth of focus of the image light emitted from the tiled waveguide display.

<FIG> is a cross-section <NUM> of the NED <NUM> illustrated in <FIG>, in accordance with an embodiment. The display <NUM> includes at least one display assembly <NUM>. An exit pupil <NUM> is a location where the eye <NUM> is positioned when the user wears the NED <NUM>. For purposes of illustration, <FIG> shows the cross section <NUM> associated with a single eye <NUM> and a single display assembly <NUM>, but in alternative embodiments not shown, another waveguide display assembly which is separate from the waveguide display assembly <NUM> shown in <FIG>, provides image light to another eye <NUM> of the user.

The display assembly <NUM>, as illustrated below in <FIG>, is configured to direct the image light to the eye <NUM> through the exit pupil <NUM>. The display assembly <NUM> may be composed of one or more materials (e.g., plastic, glass, etc.) with one or more refractive indices that effectively minimize the weight and widen a field of view (hereinafter abbreviated as 'FOV') of the NED <NUM>. In alternate configurations, the NED <NUM> includes one or more optical elements between the display assembly <NUM> and the eye <NUM>. The optical elements may act to, e.g., correct aberrations in image light emitted from the display assembly <NUM>, magnify image light emitted from the display assembly <NUM>, some other optical adjustment of image light emitted from the display assembly <NUM>, or some combination thereof. The example for optical elements may include an aperture, a Fresnel lens, a convex lens, a concave lens, a filter, or any other suitable optical element that affects image light.

In some embodiments, the display assembly <NUM> includes one or more tiled waveguide displays. In some embodiments, the tiled waveguide display may be part of the stacked waveguide display, or the varifocal display. The tiled waveguide display is a display that can widen a field of view of image light emitted from the waveguide display. The stacked waveguide display is a polychromatic display (e.g., a red-green-blue (RGB) display) created by stacking the tiled waveguide displays whose respective monochromatic sources are of different colors.

<FIG> illustrates an isometric view of a waveguide display <NUM>, in accordance with an embodiment. In some embodiments, the waveguide display <NUM> (may also be referred to as a tiled waveguide display) is a component (e.g., display assembly <NUM>) of the NED <NUM>. In alternate embodiments, the waveguide display <NUM> is part of some other NED, or other system that directs display image light to a particular location.

The waveguide display <NUM> includes at least a tiled waveguide assembly <NUM>, an output waveguide <NUM>, and a controller <NUM>. For purposes of illustration, <FIG> shows the waveguide display <NUM> associated with a single eye <NUM>, but in some embodiments, another waveguide display separate (or partially separate) from the waveguide display <NUM>, provides image light to another eye of the user. In a partially separate system, one or more components may be shared between waveguide displays for each eye.

The tiled waveguide assembly <NUM> generates image light. The tiled waveguide assembly <NUM> includes a plurality of optical sources, a source waveguide, and a controller (e.g., as further described below with regard to <FIG>). The tiled waveguide assembly <NUM> generates and outputs image light <NUM> to a coupling element <NUM> of the output waveguide <NUM>.

The output waveguide <NUM> is an optical waveguide that outputs image light to an eye <NUM> of a user. The output waveguide <NUM> receives the image light <NUM> at one or more coupling elements <NUM>, and guides the received input image light to one or more decoupling elements <NUM>. In some embodiments, the coupling element <NUM> couples the image light <NUM> from the tiled waveguide assembly <NUM> into the output waveguide <NUM>. The coupling element <NUM> may be, e.g., a diffraction grating, a holographic grating, some other element that couples the image light <NUM> into the output waveguide <NUM>, or some combination thereof. For example, in embodiments where the coupling element <NUM> is diffraction grating, the pitch of the diffraction grating is chosen such that total internal reflection occurs, and the image light <NUM> propagates internally toward the decoupling element <NUM>. For example, the pitch of the diffraction grating may be in the range of <NUM> to <NUM>.

The decoupling element <NUM> decouples the total internally reflected image light from the output waveguide <NUM>. The decoupling element <NUM> may be, e.g., a diffraction grating, a holographic grating, some other element that decouples image light out of the output waveguide <NUM>, or some combination thereof. For example, in embodiments where the decoupling element <NUM> is a diffraction grating, the pitch of the diffraction grating is chosen to cause incident image light to exit the output waveguide <NUM>. For example, the pitch of the diffraction grating may be in the range of <NUM> to <NUM>. The pitch of the diffraction grating is chosen such that the image light <NUM> from the plurality of optical sources undergoes a total internal reflection inside the output waveguide <NUM> without leakage through higher order diffraction (e.g. second reflected order). An orientation and position of the image light exiting from the output waveguide <NUM> is controlled by changing an orientation and position of the image light <NUM> entering the coupling element <NUM>. In some embodiments, the direction of the image light exiting from the output waveguide <NUM> is same as the direction of the image light <NUM>. In one example, the position of the image light exiting from the output waveguide <NUM> is controlled by the location of the plurality of optical sources of the tiled waveguide assembly <NUM>, the location of the coupling element <NUM> and the location of the decoupling element <NUM>. Any change in the orientation of at least an optical source to cover a portion of the total FOV causes the image light exiting from the output waveguide <NUM> to cover the same portion of the total FOV. The total FOV is obtained by using a plurality of optical sources that cover the entire FOV. In addition, the total FOV is a function of a refractive index of the output waveguide <NUM>, the pitch of the diffraction grating, a total number of optical sources of the tiled waveguide assembly <NUM>, and a requirement of having no leakage light from the output waveguide <NUM> via second order diffraction.

The output waveguide <NUM> may be composed of one or more materials that facilitate total internal reflection of the image light <NUM>. The output waveguide <NUM> may be composed of e.g., silicon, plastic, glass, or polymers, or some combination thereof. The output waveguide <NUM> has a relatively small form factor. For example, the output waveguide <NUM> may be approximately <NUM> wide along X-dimension, <NUM> long along Y-dimension and <NUM>-<NUM> thick along Z-dimension.

The controller <NUM> controls the scanning operations of the tiled waveguide assembly <NUM>. The controller <NUM> determines display instructions for the tiled waveguide assembly <NUM> based at least on the one or more display instructions. Display instructions are instructions to render one or more images. In some embodiments, display instructions may simply be an image file (e.g., bitmap). The display instructions may be received from, e.g., a console of a VR system (e.g., as described below in conjunction with <FIG>). Display instructions are instructions used by the tiled waveguide assembly <NUM> to generate image light <NUM>. The display instructions may include, e.g., a type of a source of image light (e.g. monochromatic, polychromatic), an identifier for a particular light source assembly, an identifier for a particular tiled waveguide assembly, a scanning rate, an orientation of the source, one or more illumination parameters (described below with reference to <FIG>), or some combination thereof. The controller <NUM> receives display instructions that controls the orientation of the expanded light <NUM> associated with a total field of view of the image light exiting the output waveguide <NUM>. For example, the total field of view can be a sum of a field of view of each of the plurality of optical sources of the tiled waveguide assembly <NUM>. In some embodiments, the total field of view can be a weighted sum of the field of view of each of the plurality of optical sources with the weights of each of the individual field of view determined based on an amount of overlap between the field of view from different optical sources. In some embodiments, the controller <NUM> also receives display instructions that includes identifier information to select the tiled waveguide assembly that receives the display instructions. The controller <NUM> includes a combination of hardware, software, and/or firmware not shown here so as not to obscure other aspects of the disclosure.

<FIG> illustrates an alternate view of the waveguide display <NUM>, in accordance with an embodiment. <FIG> is an embodiment of the waveguide display <NUM> of <FIG>, and all the details described above with reference to <FIG> apply to <FIG> as well. <FIG> illustrates the propagation of one or more reflected image light <NUM> through the tiled waveguide assembly <NUM>.

The tiled waveguide assembly <NUM> receives image light from each of the optical source assemblies 410A and 410B, described in detail below in conjunction with <FIG>, and expands each of the image light along two opposite directions. The tiled waveguide assembly <NUM> generates a reflected light 315A that undergoes total internal reflection and propagates generally along a negative X-dimension. The tiled waveguide assembly <NUM> generates a reflected light 315B that undergoes total internal reflection and propagates generally along a positive X-dimension. The direction of propagation of the reflected light <NUM> is based on the pitch of the diffraction gratings and the occurrence of total internal reflection of the image light from each of the plurality of optical sources for a desired range of angles of incidence to achieve a specific order of diffraction of interest. For example, to achieve a positive first order of diffraction (+<NUM>), the pitch of diffraction grating of the coupling element <NUM> is designed such that the reflected light 315B propagates along the positive X direction. Similarly, the pitch of another diffraction grating of the coupling element <NUM> is designed such that the reflected light 315A propagates along the negative X direction to achieve a negative first order of diffraction (-<NUM>). The tiled waveguide assembly <NUM> generates and outputs an image light <NUM> to the output waveguide <NUM>. In some embodiments, the image light <NUM> includes an image light 340A and an image light 340B. The image light <NUM> undergoes total internal reflection at the output waveguide <NUM> as illustrated in <FIG>. The image light <NUM> decouples through the decoupling element <NUM> as expanded light <NUM> and reaches the eye <NUM>. In some embodiments, the expanded light 370A represents an expanded image light emitted at a perpendicular direction to the surface of the output waveguide <NUM>. The expanded light 370B represents an image light emitted at an angle of inclination to the surface of the output waveguide <NUM>. In some configurations, the angle of inclination of the expanded image light 370B can range from -<NUM> degrees to +<NUM> degrees.

<FIG> an isometric view of a waveguide display <NUM> including multiple tiled waveguide assemblies 310A and 310B, in accordance with an embodiment. <FIG> is an embodiment of the waveguide display <NUM> of <FIG>. The waveguide display <NUM> of <FIG> includes a tiled waveguide assembly 310A, a tiled waveguide assembly 310B, an output waveguide 320B, and the controller <NUM>. The tiled waveguide assembly 310A and 310B are substantially similar to the tiled waveguide assembly <NUM> of <FIG>. The output waveguide 320B is structurally similar to the output waveguide <NUM> of <FIG> except for a coupling element 350B. The coupling element 350B is an embodiment of the coupling element <NUM> of <FIG>.

The tiled waveguide assembly 310A outputs an image light 340A to the coupling element 350A. The tiled waveguide assembly 310B outputs an image light 340B to the coupling element 350B. The image light 340A and 340B are embodiments of the image light <NUM> of <FIG>. In the example of <FIG>, the tiled waveguide assembly 310A is oriented along the x-dimension and the tiled waveguide assembly 310B is oriented along the same x-dimension at an offset from the tiled waveguide assembly 310A. In some embodiments, the offset is determined by a desired size of an eye box, the total FOV, and an eye relief distance. The offset is also associated with defining how large of an output area (e.g. <NUM> x <NUM>) is needed to give the desired size of the eye box for a given total FOV, and the eye relief distance.

<FIG> illustrates a cross-section <NUM> of the waveguide assembly <NUM>, in accordance with an embodiment. The cross-section <NUM> of the tiled waveguide assembly <NUM> includes a source assembly 410A, a source assembly 410B, and a source waveguide <NUM>.

The source assemblies 410A and 410B generate light in accordance with display instructions from the controller <NUM>. The source assembly 410A includes a source 440A, and an optics system 450A. The source 440A is a source of light that generates at least a coherent or partially coherent image light. The source 440A may be, e.g., a laser diode, a vertical cavity surface emitting laser, a light emitting diode, a tunable laser, or some other light source that emits coherent or partially coherent light. The source 440A emits light in a visible band (e.g., from about <NUM> to <NUM>), and it may emit light that is continuous or pulsed. In some embodiments, the source 440A may be a laser that emits light at a particular wavelength (e.g., <NUM> nanometers). The source 440A emits light in accordance with one or more illumination parameters received from the controller <NUM>. An illumination parameter is an instruction used by the source 440A to generate light. An illumination parameter may include, e.g., source wavelength, pulse rate, pulse amplitude, beam type (continuous or pulsed), other parameter(s) that affect the emitted light, or some combination thereof. The source assembly 410B is structurally similar to the source assembly 410A except for the identifier information in the display instructions from the controller <NUM>.

In some embodiments, the source assembly 410A and the source assembly 410B are located on opposite ends of the source waveguide <NUM>. The source assembly 410A generates an image light directed along the negative z-dimension and in-coupled by the source waveguide <NUM> so as to propagate toward the negative x-dimension. The source assembly 410B generates an image light directed along the positive z-dimension and in-coupled by the source waveguide <NUM> so as to propagate toward the positive x-dimension.

The optics system <NUM> includes one or more optical components that condition the light from the source <NUM>. Conditioning light from the source <NUM> may include, e.g., expanding, collimating, adjusting orientation in accordance with instructions from the controller <NUM>, some other adjustment of the light, or some combination thereof. The one or more optical components may include, e.g., lenses, mirrors, apertures, gratings, or some combination thereof. Light emitted from the optics system <NUM> (and also the source assembly <NUM>) is referred to as image light <NUM>. The optics system <NUM> outputs the image light <NUM> toward the source waveguide <NUM>.

The source waveguide <NUM> is an optical waveguide. The source waveguide <NUM> may be composed of one or more materials that facilitate total internal reflection of the image light <NUM>. The source waveguide <NUM> may be composed of e.g., silicon, plastic, glass, or polymers, a material with an index of refraction below <NUM>, or some combination thereof. The source waveguide <NUM> has a relatively small form factor. For example, the source waveguide <NUM> may be approximately <NUM> long along X-dimension, <NUM> wide along Y-dimension, and <NUM>-<NUM> thick along Z-dimension.

The source waveguide <NUM> includes a coupling element 460A and a decoupling element <NUM>. The source waveguide <NUM> receives the image light 455A emitted from the source assembly 410A at the coupling element 460A. The coupling element 460A couples the image light 455A from the source assembly 410A into the source waveguide <NUM>. The coupling element 460A may be, e.g., a diffraction grating, a holographic grating, a reflective surface, a prismatic structure, a side or edge of the body of the source waveguide <NUM>, some other element that couples the image light 455A into the source waveguide <NUM>, or some combination thereof. For example, in embodiments where the coupling element 460A is diffraction grating, the pitch of the diffraction grating is chosen such that total internal reflection occurs, and the image light 455A propagates internally toward the decoupling element <NUM>. For example, the pitch of the diffraction grating may be in the range of <NUM> to <NUM>.

The decoupling element <NUM> decouples the total internally reflected image light 455A from the source waveguide <NUM>. In some embodiments, the decoupling element <NUM> includes a variation in the design of the diffraction grating (e.g. pitch) so that decoupling of an image light is more efficient to a given range of angles of incidence in certain parts of the diffraction grating. The decoupling element <NUM> may be, e.g., a diffraction grating, a holographic grating, a reflective surface, a prismatic structure, a side or edge of the body of the source waveguide <NUM>, some other element that decouples image light out of the source waveguide <NUM>, or some combination thereof. For example, in embodiments where the decoupling element <NUM> is a diffraction grating, the pitch of the diffraction grating is chosen to cause incident image light to exit the source waveguide <NUM>. An orientation of the image light exiting from the source waveguide <NUM> may be altered by varying the orientation of the image light exiting the source assembly 410A, varying an orientation of the source assembly 410A, or some combination thereof. For example, the pitch of the diffraction grating may be in the range of <NUM> to <NUM>.

In a typical near-eye-display (NED) system using diffraction gratings as coupling elements, the limit for the FOV is based on satisfying two physical conditions: (<NUM>) an occurrence of total internal reflection of image light coupled into the source waveguide <NUM> and (<NUM>) an existence of a first order diffraction of the coupling element 460A and 460B over the FOV of their respective image sources. Conventional methods used by the NED systems based on diffracting gratings rely on satisfying the above two physical conditions in order to achieve a large FOV (e.g. above <NUM> degrees) by using materials with a high refractive index, wherein the said methods add significantly heavy and expensive components to the NED system. In contrast, the waveguide display <NUM> relies on splitting the FOV into two half spaces by separating the coupling elements 460A and 460B, each of the coupling elements configured to receive the image light 455A and the image light 455B, respectively. Accordingly, the value of the pitch of the diffraction grating inside the coupling element 460A determines the limit for the first order diffraction of the image light 455A and the limit for the total internal reflection of the image light 455A inside the source waveguide <NUM>.

As both the coupling element 460A and the coupling element 460B reflect an image light to the same decoupling element <NUM>, the pitch of the diffraction grating is the same in order to form a non-distorted image. In this case, the optical sources are configured to provide half of the FOV, for example, the image light 455A provides from -FOV/<NUM> to <NUM> and the image light 455B provides from <NUM> to FOV/<NUM>. In a second example, the image light 455A provides from <NUM> to FOV/<NUM> and the image light 455B provides from -FOV/<NUM> to <NUM>. The pitch of the diffraction grating is selected so that the FOV corresponding to the image light 455A is coupled into a positive first (+<NUM>) order of diffraction and the FOV of the image light 455B is coupled into a negative first (-<NUM>) order of diffraction. To maximize the brightness of the display presented to the user's eye, the grating profile of the coupling element 460A and the coupling element 460B are designed separately to optimize the amount of light coupled into the desired diffraction orders, respectively. In addition, the pitch of the diffraction grating may be adjusted to minimize light leakage out of the source waveguide <NUM> via diffraction to higher order diffracted modes.

The decoupling element <NUM> outputs the image light 440A and the image light 440B to the output waveguide <NUM>. The value of the pitch of the diffraction grating inside the decoupling element <NUM> is selected to be equal to that of the coupling element 460A and the coupling element 460B in order to form an undistorted image for the image light in the display presented to the user's eyes. The grating profile is designed so that light is decoupled from the source waveguide <NUM> partially in each interception of the image light with the decoupling element <NUM>. The multiple partial diffractions of the light with the decoupling element <NUM> results in the total expansion along the x-dimension of the image light <NUM>.

The image light 440A exiting the source waveguide <NUM> is expanded at least along one dimension (e.g., may be elongated along x-dimension). The image light <NUM> couples to an output waveguide <NUM> as described above with reference to <FIG>.

In some embodiments, the decoupling element <NUM> has an extended length in the direction of propagation of an image light trapped inside the source waveguide <NUM>. The decoupling element <NUM> may represent an exit pupil of the source waveguide <NUM>.

The controller <NUM> controls the source assembly 410A by providing display instructions to the source assembly 410A. The display instructions cause the source assembly 410A to render light such that image light exiting the decoupling element <NUM> of the output waveguide <NUM> scans out one or more 2D images. For example, the display instructions may cause the tiled waveguide assembly <NUM> to generate a two-dimensional image from a <NUM>-D array pattern of image light generated by the source assembly <NUM> (e.g. using a <NUM>-D array of MicroLEDs and a collimating lens). The controller <NUM> controls the source waveguide <NUM> by providing scanning instructions to the source waveguide <NUM>. The scanning instructions cause the source waveguide <NUM> to perform a scanning operation of the source waveguide <NUM>, in accordance with a scan pattern (e.g., raster, interlaced, etc.) The display instructions control an intensity of light emitted from the source <NUM>, and the optics system <NUM> scans out the image by rapidly adjusting orientation of the emitted light. If done fast enough, a human eye integrates the scanned pattern into a single 2D image. The display instructions also control a direction (e.g. clock-wise or anti-clockwise) and a speed of rotation of the source waveguide <NUM>.

In some configurations, the total field of view of the tiled waveguide display <NUM> can be determined from the sum of the field of view corresponding to the image light 455A and the image light 455B. In a typical NED system, the field of view is restricted to half of the total field of view of the tiled waveguide display <NUM> as there is no splitting of the field of view using two source assemblies. In addition, the tiled waveguide display <NUM> has a relaxation in the form factor of the light source assemblies 410A and 410B as the field of view for each of the sources 440A and 440B is half of the field of view for a waveguide display with a single light source.

<FIG> is a block diagram of a system <NUM> including the NED <NUM>, according to an embodiment. The system <NUM> shown by <FIG> comprises the NED <NUM>, an imaging device <NUM>, and a VR input interface <NUM> that are each coupled to the VR console <NUM>. While <FIG> shows an example system <NUM> including one NED <NUM>, one imaging device <NUM>, and one VR input interface <NUM>, in other embodiments, any number of these components may be included in the system <NUM>. For example, there may be multiple NEDs <NUM> each having an associated VR input interface <NUM> and being monitored by one or more imaging devices <NUM>, with each NED <NUM>, VR input interface <NUM>, and imaging devices <NUM> communicating with the VR console <NUM>. In alternative configurations, different and/or additional components may be included in the system <NUM>. Similarly, functionality of one or more of the components can be distributed among the components in a different manner than is described here. For example, some or all of the functionality of the VR console <NUM> may be contained within the NED <NUM>. Additionally, in some embodiments the VR system <NUM> may be modified to include other system environments, such as an AR system environment, or more generally an artificial reality environment.

The IMU <NUM> is an electronic device that generates fast calibration data indicating an estimated position of the NED <NUM> relative to an initial position of the NED <NUM> based on measurement signals received from one or more of the position sensors <NUM>. A position sensor <NUM> generates one or more measurement signals in response to motion of the NED <NUM>. Examples of position sensors <NUM> include: one or more accelerometers, one or more gyroscopes, one or more magnetometers, another suitable type of sensor that detects motion, a type of sensor used for error correction of the IMU <NUM>, or some combination thereof. The position sensors <NUM> may be located external to the IMU <NUM>, internal to the IMU <NUM>, or some combination thereof. In the embodiment shown by <FIG>, the position sensors <NUM> are located within the IMU <NUM>, and neither the IMU <NUM> nor the position sensors <NUM> are visible to the user (e.g., located beneath an outer surface of the NED <NUM>).

Based on the one or more measurement signals generated by the one or more position sensors <NUM>, the IMU <NUM> generates fast calibration data indicating an estimated position of the NED <NUM> relative to an initial position of the NED <NUM>. For example, the position sensors <NUM> include multiple accelerometers to measure translational motion (forward/back, up/down, left/right) and multiple gyroscopes to measure rotational motion (e.g., pitch, yaw, roll). In some embodiments, the IMU <NUM> rapidly samples the measurement signals from various position sensors <NUM> and calculates the estimated position of the NED <NUM> from the sampled data. For example, the IMU <NUM> integrates the measurement signals received from one or more accelerometers over time to estimate a velocity vector and integrates the velocity vector over time to determine an estimated position of a reference point on the NED <NUM>. The reference point is a point that may be used to describe the position of the NED <NUM>. While the reference point may generally be defined as a point in space; however, in practice, the reference point is defined as a point within the NED <NUM> (e.g., the reference point <NUM> representing a center of the IMU <NUM>).

The imaging device <NUM> generates slow calibration data in accordance with calibration parameters received from the VR console <NUM>. The imaging device <NUM> may include one or more cameras, one or more video cameras, one or more filters (e.g., used to increase signal to noise ratio), or any combination thereof. The imaging device <NUM> is configured to detect image light emitted or reflected in the FOV of the imaging device <NUM>. In embodiments where the NED <NUM> include passive elements (e.g., a retroreflector), the imaging device <NUM> may retro-reflect the image light towards the image light source in the imaging device <NUM>. Slow calibration data is communicated from the imaging device <NUM> to the VR console <NUM>, and the imaging device <NUM> receives one or more calibration parameters from the VR console <NUM> to adjust one or more imaging parameters (e.g., focal length, focus, frame rate, ISO, sensor temperature, shutter speed, aperture, etc.).

The VR input interface <NUM> is a device that allows a user to send action requests to the VR console <NUM>. An action request is a request to perform a particular action. For example, an action request may be to start or end an application or to perform a particular action within the application. The VR input interface <NUM> may include one or more input devices. Example input devices include: a keyboard, a mouse, a game controller, or any other suitable device for receiving action requests and communicating the received action requests to the VR console <NUM>. An action request received by the VR input interface <NUM> is communicated to the VR console <NUM>, which performs an action corresponding to the action request. In some embodiments, the VR input interface <NUM> may provide haptic feedback to the user in accordance with instructions received from the VR console <NUM>. For example, haptic feedback is provided when an action request is received, or the VR console <NUM> communicates instructions to the VR input interface <NUM> causing the VR input interface <NUM> to generate haptic feedback when the VR console <NUM> performs an action.

The VR console <NUM> provides media to the NED <NUM> for presentation to the user in accordance with information received from one or more of: the imaging device <NUM>, the NED <NUM>, and the VR input interface <NUM>. In the example shown in <FIG>, the VR console <NUM> includes an application store <NUM>, a tracking module <NUM>, and a VR engine <NUM>. Some embodiments of the VR console <NUM> have different modules than those described in conjunction with <FIG>. Similarly, the functions further described below may be distributed among components of the VR console <NUM> in a different manner than is described here.

The application store <NUM> stores one or more applications for execution by the VR console <NUM>. An application is a group of instructions, that when executed by a processor, generates content for presentation to the user. Content generated by an application may be in response to inputs received from the user via movement of the NED <NUM> or the VR input interface <NUM>. Examples of applications include: gaming applications, conferencing applications, video playback application, or other suitable applications.

The tracking module <NUM> calibrates the VR system <NUM> using one or more calibration parameters and may adjust one or more calibration parameters to reduce error in determination of the position of the NED <NUM>. For example, the tracking module <NUM> adjusts the focus of the imaging device <NUM> to obtain a more accurate position on the VR headset. Moreover, calibration performed by the tracking module <NUM> also accounts for information received from the IMU <NUM>. Additionally, if tracking of the NED <NUM> is lost, the tracking module <NUM> re-calibrates some or the entire system environment <NUM>.

The tracking module <NUM> tracks movements of the NED <NUM> using slow calibration information from the imaging device <NUM>. The tracking module <NUM> also determines positions of a reference point of the NED <NUM> using position information from the fast calibration information. Additionally, in some embodiments, the tracking module <NUM> may use portions of the fast calibration information, the slow calibration information, or some combination thereof, to predict a future location of the NED <NUM>. The tracking module <NUM> provides the estimated or predicted future position of the NED <NUM> to the VR engine <NUM>.

The VR engine <NUM> executes applications within the system <NUM> and receives position information, acceleration information, velocity information, predicted future positions, or some combination thereof of the NED <NUM> from the tracking module <NUM>. In some embodiments, the information received by the VR engine <NUM> may be used for producing a signal (e.g., display instructions) to the waveguide display assembly <NUM> that determines the type of content presented to the user. For example, if the received information indicates that the user has looked to the left, the VR engine <NUM> generates content for the NED <NUM> that mirrors the user's movement in a virtual environment by determining the type of source and the waveguide that operate in the waveguide display assembly <NUM>. For example, the VR engine <NUM> may produce a display instruction that would cause the waveguide display assembly <NUM> to generate content with red, green, and blue color. Additionally, the VR engine <NUM> performs an action within an application executing on the VR console <NUM> in response to an action request received from the VR input interface <NUM> and provides feedback to the user that the action was performed. The provided feedback may be visual or audible feedback via the NED <NUM> or haptic feedback via the VR input interface <NUM>.

The foregoing description of the embodiments of the disclosure has been presented for the purpose of illustration; it is not intended to be exhaustive or to limit the disclosure to the precise forms disclosed. Persons skilled in the relevant art can appreciate that many modifications and variations are possible in light of the above disclosure.

Some portions of this description describe the embodiments of the disclosure in terms of algorithms and symbolic representations of operations on information. These algorithmic descriptions and representations are commonly used by those skilled in the data processing arts to convey the substance of their work effectively to others skilled in the art. These operations, while described functionally, computationally, or logically, are understood to be implemented by computer programs or equivalent electrical circuits, microcode, or the like. Furthermore, it has also proven convenient at times, to refer to these arrangements of operations as modules, without loss of generality. The described operations and their associated modules may be embodied in software, firmware, hardware, or any combinations thereof.

Embodiments of the disclosure may also relate to an apparatus for performing the operations herein. This apparatus may be specially constructed for the required purposes, and/or it may comprise a general-purpose computing device selectively activated or reconfigured by a computer program stored in the computer. Such a computer program may be stored in a non-transitory, tangible computer readable storage medium, or any type of media suitable for storing electronic instructions, which may be coupled to a computer system bus. Furthermore, any computing systems referred to in the specification may include a single processor or may be architectures employing multiple processor designs for increased computing capability.

Embodiments of the disclosure may also relate to a product that is produced by a computing process described herein. Such a product may comprise information resulting from a computing process, where the information is stored on a non-transitory, tangible computer readable storage medium and may include any embodiment of a computer program product or other data combination described herein.

Claim 1:
A waveguide assembly (<NUM>) for a waveguide display, the waveguide assembly comprising a source waveguide (<NUM>) and an output waveguide, the
source waveguide comprising:
a first entrance area, a second entrance area, a first exit area, and a second exit area, and the first entrance area and the second entrance area are located on opposite ends of the source waveguide with the first exit area and the second exit area located between the first entrance area and the second entrance area, the source waveguide configured to:
in-couple a first image light (455A) at the first entrance area wherein the first image light corresponds to a first portion of an image, expand the first image light in a first dimension using total internal reflection, and output the expanded first image light via the first exit area, and in-couple a second image light (455B) at the second entrance area wherein the second image light corresponds to a second portion of the image that is different than the first portion of the image, expand the second image light in the first dimension using total internal reflection, and output the expanded second image light via the second exit area, and
the output waveguide (<NUM>) comprising:
a third entrance area and a third exit area, the output waveguide (<NUM>) configured to in-couple the first image light and the second image light at the third entrance area, expand the expanded first image light and the expanded second image light in at least one dimension that is orthogonal to the first dimension to generate a portion of a magnified image, and output the portion of the magnified image via the third exit area towards an eyebox.