Near-eye display with uniform eye-box plane illumination

Abstract

A near-eye display includes a projector configured to produce an input beam and an optical waveguide. The optical waveguide includes two major surfaces and a coupling-in portion configured to cause the input beam to reflect between the major surfaces at a beam angle. The optical waveguide also includes a set of first facets configured to partially reflect the input beam as a plurality of beams. The optical waveguide further includes a set of second facets disposed at a facet angle relative to the major surfaces and configured to partially reflect the beams as a plurality of output beams out of the optical waveguide. In order to uniformly fill an eye-box plane, the beam angle and the facet angle may be made the same, the coupling-in portion may be configured to be a certain length, and / or a mixer implemented that is offset from a midplane between the major surfaces.

Description

NEAR-EYE DISPLAY WITH UNIFORM EYE-BOX PLANE ILLUMINATIONCROSS-REFERENCE TO RELATED APPLICATION

[0001] The subject application claims the benefit of U. S. Provisional Application No.63 / 716,743, filed on November 6, 2024, and U. S. Provisional Application No. 63 / 741,899, filed on January 5, 2025; the entire disclosures of which are incorporated herein by reference.FIELD

[0002] This disclosure is directed to optical waveguides, such as those used in near-eye displays.BACKGROUND

[0003] Optical waveguides are implemented in a variety of environments to manipulate and direct beams of light. For example, many near-eye displays (NEDs) and heads-up displays (HUDs) (e.g,, those used for virtual reality (VR) or augmented reality' (AR) applications) utilize an optical waveguide to direct beams generated by a projector to a user’s eye. The beams are injected into the optical waveguide via an aperture, propagate through the optical waveguide via total internal reflection (TIR), and exit the optical waveguide towards the user’s eye (e.g., an eye box) via one or more coupling-out elements.

[0004] In many cases, the optical waveguide also expands the beams in one or more dimensions. For example, the optical waveguide may be configured for two-dimensional (2D) aperture expansion via two sets of partially reflective facets, typically disposed in orthogonal directions. The first set expands the aperture in one dimension and reflects the image beam onwards to the second set which expands the aperture in a second direction and reflects the image towards the eye of the user. In such cases, an incorrect arrangement of the aperture and / or other components of the optical waveguide may result in reduced modulation transfer function (MTF) in regions in the eye box. In other words, beams may be coupled out towards the eye box in a non-uniform fashion (e.g., the eye box may be under or over filled / illuminated).SUMMARY

[0005] A near-eye display is described herein. The near-eye display includes a projector configured to produce an input beam and an optical waveguide. The optical waveguide includes a pair of major surfaces that are parallel and a coupling-in portion configured to receive the input beam and cause the input beam to reflect between the major surfaces at a beam angle relative to the major surfaces. The optical waveguide also includes a set of first facets disposed between the major surfaces that are planar, parallel, and partially reflective and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality of beams. The optical waveguide further includes a set of second facets disposed between the major surfaces that are planar, parallel, partially reflective, non-parallel with the first facets, and disposed at a facet angle relative to the major surfaces and configured to receive the plurality of beams from the set of first facets and partially reflect the plurality of beams as a plurality of output beams out of the optical waveguide. The beam angle and the facet angle are the same.

[0006] A method of configuring an optical waveguide for a near-eye display is also described herein. The method includes providing for a coupling-in portion within the optical waveguide that is configured to receive an input beam of the near-eye display and cause the input beam to reflect between major surfaces of the optical waveguide at a beam angle relative to the major surfaces. The method also includes providing for a set of first facets disposed between the major surfaces that are planar, parallel, and partially reflective and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality’ of beams. The method further includes providing for a set of second facets disposed between the major surfaces that are planar, parallel, partially reflective, non-parallel with the first facets, and disposed at a facet angle relative to the major surfaces and configured to receive the plurality’ of beams from the set of first facets and partially reflect the plurality of beams as a plurality of output beams out of the optical wavegui de. The method also includes configuring the beam angle and the facet angle such that they are the same.

[0007] Another near-eye display is described herein. The other near-eye display includes a projector configured to produce an input beam and an optical waveguide. The optical waveguideincludes a pair of major surfaces that are parallel and a coupling-in portion including a mirror configured to receive the input beam and cause the input beam to reflect between the major surfaces at a beam angle relative to the major surfaces. A length of the mirror multiplied by a cosine of an angle of the mirror relative to the major surfaces is equal to an input beam width. The optical waveguide also includes a set of first facets disposed between the major surfaces that are planar, parallel, and partially reflective and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality of beams. The optical waveguide further includes a set of second facets disposed between the major surfaces that are planar, parallel, partially reflective, non-parallel with the first facets, and disposed at a facet angle relative to the major surfaces and configured to receive the plurality of beams from the set of first facets and partially reflect the plurality of beams as a plurality of output beams out of the optical waveguide.

[0008] Another method of configuring an optical waveguide for a near-eye display is described herein. The other method includes providing for a coupling-in portion within the optical waveguide. The coupling-in portion includes a mirror configured to receive an input beam of the near-eye display and cause the input beam to reflect between major surfaces of the optical waveguide at a beam angle relative to the major surfaces. The other method also includes providing for a set of first facets disposed between the major surfaces. The set of first facets are planar, parallel, and partially reflective and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality of beams. The other method further includes providing for a set of second facets disposed between the major surfaces. The set of second facets are planar, parallel, partially reflective, non-parallel with the first facets, and disposed at a facet angle relative to the major surfaces and configured to receive the plurality of beams from the set of first facets and partially reflect the plurality of beams as a plurality of output beams out of the optical waveguide. The other method also includes configuring a mirror length of the mirror such that the mirror length multiplied by a cosine of a mirror angle of the mirror relative to the major surfaces is equal to an input beam width of the input beam.

[0009] Yet another near-eye display is described herein. The other near-eye display includes a projector configured to produce an input beam and an optical waveguide. The optical waveguide includes a pair of major surfaces that are parallel and a coupling-in portion configured to receive the input beam and cause the input beam to reflect between the major surfaces at a beam angle relative to the major surfaces. The optical waveguide also includes a set of first facets disposed between the major surfaces that are planar, parallel, and partially reflective and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality of beams. The optical waveguide further includes a set of second facets disposed between the major surfaces that are planar, parallel, partially reflective, non- parallel with the first facets, and disposed at a facet angle relative to the major surfaces and configured to receive the plurality' of beams from the set of first facets and partially reflect the plurality' of beams as a plurality’ of output beams out of the optical waveguide. An input beam width of the input beam is larger than half a length of the second facets multiplied by a cosine of the facet angle. The optical waveguide also includes a mixer disposed between the coupling-in portion and the set of second facets, parallel to the major surfaces, and offset from a midplane between the major surfaces.

[0010] Yet another method of configuring an optical waveguide for a near-eye display is described herein. The other method includes providing for a coupling-in portion within the optical waveguide configured to receive an input beam of the near-eye display’ and cause the input beam to reflect between major surfaces of the optical waveguide at a beam angle relative to the major surfaces. The other method also includes providing for a set of first facets disposed between the major surfaces that are planar, parallel, and partially reflective and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality’ of beams. The other method further includes providing for a set of second facets disposed between the major surfaces that are planar, parallel, partially reflective, non-parallel with the first facets, and disposed at a facet angle relative to the major surfaces and configured to receive the plurality' of beams from the set of first facets and partially reflect the plurality of beams as a plurality of output beams out of the optical waveguide. The other method also includes providing for a mixer disposed between the coupling-in portion and the set of secondfacets, parallel to the major surfaces, and offset from a midplane between the major surfaces. The other method further includes configuring an amount of the offset.

[0011] Eyeglasses are also described herein. The eyeglasses include a frame configured to hold any of the near-eye displays above.

[0012] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description. In the drawings, tike reference numbers indicate identical or functionally similar elements.BRIEF DESCRIPTION OF THE DRAWINGS

[0013] FIG. 1 illustrates an example of a near-eye display with an optical waveguide in accordance with this disclosure.

[0014] FIG. 2 illustrates an example of the optical waveguide of FIG, 1 shown folded without beams.

[0015] FIG. 3 illustrates another example of the optical waveguide of FIG. 1 shown unfolded with beams.

[0016] FIG. 4 A illustrates another example of the optical waveguide of FIG. 1 shown unfolded with beams.

[0017] FIG. 4B illustrates an enlarged portion of FIG, 4 A.

[0018] FIG. 5A illustrates another example of the optical waveguide of FIG. 1 shown unfolded with beams,

[0019] FIG. 5B illustrates an enlarged portion of FIG. 5 A.

[0020] FIG. 6 illustrates a method of configuring an optical waveguide for use in a near-eye display.

[0021] FIG. 7 illustrates another method of configuring an optical waveguide for use in a near-eye display.

[0022] FIG. 8 illustrates another method of configuring an optical waveguide for use in a near-eye display.DETAILED DESCRIPTIONOverview

[0023] Performance results in many applications of optical waveguides are often tied to an ability to configure / control beams entering, propagating, and exiting the optical waveguides. For example, an incorrect configuration / arrangement of an input beam, an aperture, a coupling-in element, facets, or other components of an optical waveguide configured for 2D expansion may affect filling of an eye box (e.g., the eye box may be under or over filled).

[0024] Described herein is a near-eye display with uniform eye-box plane illumination. The near-eye display includes a projector configured to produce an input beam and an optical waveguide. The optical waveguide includes two major surfaces and a coupling-in portion configured to cause the input beam to reflect between the major surfaces at a beam angle. The optical waveguide also includes a set of first facets configured to partially reflect the input beam as a plurality of beams. The optical waveguide further includes a set of second facets disposed at a facet angle relative to the major surfaces and configured to partially reflect the beams as a plurality of output beams out of the optical waveguide.

[0025] By configuring the optical waveguide such that the beam angle and the facet angle are the same, an eye-box plane may be uniformly filled / illuminated. Alternatively or additionally, by configuring the optical waveguide such that a mirror length of a mirror of the coupling-in portion multiplied by a cosine of a mirror angle of the mirror relative to the major surfaces is equal to an input beam width of the input beam, the eye-box plane may be uniformly filled / illuminated. Alternatively or additionally, by configuring the optical waveguide such that a mixer is offsetfrom a midplane when an input beam width of the input beam is larger than half a length of the second facets multiplied by a cosine of the facet angle, the eye-box plane may be uniformly filled / illuminated. Accordingly, uniform filling / illumination of the eye box may be achieved for many different configurations of the near eye display.

[0026] In the following description, numerous specific details are set forth, such as particular structures, components, materials, dimensions, processing steps and techniques, in order to provide an understanding of the various embodiments of the present application. However, it will be appreciated by one of ordinary skill in the art that the various embodiments of the present application may be practiced without these specific details. In other instances, well-known structures or processing steps have not been described in detail in order to avoid obscuring the present application.Example Near-Eye Display

[0027] FIG. 1 illustrates an example of a near-eye display 100 with an optical waveguide 102 in accordance with this disclosure. The near-eye display 100 is illustrated as a pair of eyeglasses (e.g., augmented reality glasses); however, the near-eye display 100 may take other forms without departing from the scope of this disclosure (e.g., HUD, single eye glass, monocle).

[0028] The near-eye display 100 includes a frame 104, the optical waveguide 102, and a projector 106. The optical waveguide 102 and / or the projector 106 may be supported by the frame 104. The frame 104 may be configured to support the optical waveguide 102 on a user’s head such that the optical waveguide 102 is in front of an eye of the user.

[0029] The projector 106 is configured to produce light beams (e.g., those corresponding to images) for injection into the optical waveguide 102. There may be at least one coupling-in element (not shown), such as a prism, to facilitate the injection of the beams into the optical waveguide 102.

[0030] The optical waveguide 102 includes two major surfaces that are flat and parallel to one another and configured to cause the injected beams from the projector 106 to reflect therebetween due to total internal reflection (TIR). The optical waveguide 102 includes a firstregion 108 that includes a set of first facets (not shown) and a second region 110 that includes a set of second facets (not shown). The first region 108 (e.g., the set of first facets) is configured to expand the beams in the Y-dimension while also redirecting the beams in the X-dimension towards the second region 110. The second region 110 (e.g., the set of second facets) is configured to expand the beams in the X-dimension while also redirecting the beams out of the optical waveguide 102 in the Z-dimension (e.g., couples the beams out of the optical waveguide 102). The facets are described further below.

[0031] It should be noted that the illustrated example has another optical waveguide and another projector (e.g., to the left of the optical waveguide 102 and projector 106). As the other waveguide and projector may be similar to the optical waveguide 102 and the projector 106, respectively, those will not be discussed herein. For example, there may be a left and a right optical waveguide (e.g., for left and right eyes of a user) with corresponding projectors.Furthermore, the projector 106 may be configured to supply beams for injection into both optical waveguides. Accordingly, the configuration of the near-eye display 100 may vary without departing from the scope of this disclosure.Example Optical Waveguides

[0032] FIG. 2 illustrates an example of the optical waveguide 102.. As discussed above, the optical waveguide 102 includes major surfaces 200 (e.g., major surface 200a and major surface 200b). The major surfaces 200 are flat and parallel to one another.

[0033] The optical waveguide 102 includes the first region 108 and the second region 110. The first region 108 includes the set of first facets 202 configured to receive the beams from the projector 106 and expand the beams in the Y-direction while also redirecting the beams towards the second region 110. The second region 110 includes a set of second facets 204 configured to receive the beams from the first facets 202 and expand the beams in the X-direction while also redirecting the beams out of the optical waveguide 102. In some implementations, however, the second facets 204 may not couple the beams out of the optical waveguide 102 (e.g., the coupling out may be performed via other optical elements).

[0034] There may be a transition surface 206 (or transition plane) between the first region 108 and the second region 110. The transition surface 206 may be oriented at any angle (e.g., perpendicular to the major surfaces 200 and aligned to the Y-direction, as shown). Furthermore, alternatively or additionally, there may be a mixer (not shown) disposed between the first region 108 and the second region 110. The mixer may be disposed parallel to the major surfaces 200.

[0035] The facets (e.g., the set of first facets 202 and the set of second facets 204) are partially reflective optical elements or surfaces. The facets are configured to have various optical properties, as discussed below. The facets of each set (e.g., the first facets 202 or the second facets 204) are parallel to one another. The first facets 202 and / or the second facets 204 may be perpendicular to the major surfaces 200 or may be oblique to the major surfaces 200. For example, the first facets 202 may be perpendicular to the major surfaces 200 (e.g., aligned in the Z-direction). Furthermore, first facets 202 and / or the second facets 204 may be perpendicular to surfaces other than the major surfaces 200 or may be oblique to the other surfaces. For example, the second facets 204 may be perpendicular to an end surface of the optical waveguide 102 (e.g., aligned in the Y-direction).

[0036] The optical waveguide 102 also includes an aperture 208. The aperture 208 is configured to accept input beams such as those from the projector 106. The aperture 208 may be disposed on any surface of the optical waveguide 102 and may have any size / shape. Beneath / behind the aperture 208 may be one or more coupling-in elements (not shown). The coupling-in elements may be configured to redirect the input beams such that they propagate through the optical waveguide 102 via TIR (e.g., towards the first facets 202). For example, the coupling-in elements may comprise a mirror configured to direct the input beams towards one of the major surfaces 200 at a beam angle. The beam angle may be the same as a facet angle of the second facets 204 relative to the major surfaces 200.

[0037] FIG. 3 illustrates an example of the optical waveguide 102 showing beams. The illustrated example is shown “unfolded.” In other words, some of the beams are shown as traveling in one direction and the components are positioned accordingly. It should be noted thatthe beams reflect between the major surfaces 200 until they are coupled out by the second facets 204 towards an eye-box plane 300.

[0038] As discussed above, the optical waveguide 102 includes the major surfaces 200. The “unfolded” view places optical components and beams outside of the major surfaces 200, however, as discussed above, they are contained within the major surfaces 200 (until coupled-out). When coupled-out the beams are directed towards an eye-box plane 300. The eye-box plane 300 is associated with an eye (or eyes) of a user.

[0039] Between the major surfaces 200 are the set of second facets 204. The set of first facets 202 are not shown. The set of second facets 204 have a facet length 302 and are inclined relative to the major surfaces at a facet angle 304.

[0040] The optical waveguide 102 receives an input beam 306 (e.g., from the projector 106). The input beam 306 is received by the aperture 208 and has an input beam width 308. The input beam width 308 may be dictated by the projector 106, any intermediate optical components (e.g., lenses), or any combination thereof. The input beam 306 passes through the aperture 208 and reflects off a coupling-in portion 310. The coupling-in portion 310 may be a mirror disposed at mirror angle 312 relative to the major surfaces 200. The coupling-in portion 310 may also be a prism or other reflective component. In the illustrated example, the coupling-in portion 310 extends to both of the major surfaces 200. The coupling-in portion 310 reflects the input beam 306 such that it reflects off the major surfaces 200 at a beam angle 314. Although the input beam 306 enters the aperture 208 at a right angle in the illustrated example, the input beam 306 may enter the aperture 208 at any angle. The coupling-in portion 310 may be adjusted based on the incident angle to achieve a desired beam angle 314 (e.g., to be the same as the facet angle 304).

[0041] The beam angle 314 may be equal to the facet angle 304. In the illustrated example, the input beam width 308 is equal to the facet length 302 multiplied by a cosine of the facet angle 304. In other words, the full waveguide aperture is filled by the input beam 306. Accordingly, based on the shown / disclosed geometries, the eye-box plane 300 is fully illuminated / filled.

[0042] FIG. 4 illustrates another example of the optical waveguide 102. The illustrated example is also shown as “unfolded.” Different from the example of FIG. 3, the input beam 306 has an input beam width 308 that does not fill the waveguide aperture. For example, it may be impractical to use a full-width projector (e.g., because of form factor), and, thus, a reduced aperture projector may be used. In the illustrated example, the input beam width 308 is equal to half of the facet length 302 multiplied by a cosine of the facet angle 304.

[0043] Similar to the above, the input beam 306 passes through the aperture 208, and hits the coupling-in portion 310. The coupling-in portion 310 is configured to reflect the input beam 306 such that it reflects off the major surfaces 200 at the beam angle 314, which may be the same as the facet angle 304. The coupling-in portion 310 may have a mirror length 400 that corresponds to the input beam width 308. For example, the input beam width 308 may be equal to the mirror length 400 multiplied by a cosine of the mirror angle 312. Even if the coupling-in portion 310 were to extend to the other major surface (e.g. longer than necessary), as long as the input beam 306 is controlled (e.g., width, location, incident angle), the resultant beams will not be affected.

[0044] Because the input beam 306 is half-width, a mixer 402 may be disposed between the major surfaces 200. More specifically, the mixer 402 may be disposed between the coupling-in portion 310 and the set of second facets 204. The mixer 402 is configured to allow incident beams to pass therethrough while creating conjugate beams. The beams and the conjugate beams reflect through the optical waveguide 102 and out of the optical waveguide 102 to fill the eye- box plane 300, as illustrated. The mixer 402 may have a mixer length 404 that is equal to the input beam width 308 divided by a cosine of the facet angle 304. In this implementation, the mixer 402 is disposed at a midplane between the major surfaces 200.

[0045] FIG. 5 illustrates another example of the optical waveguide 102. The illustrated example is also shown as “unfolded.” Different from the example of FIG. 4, the input beam 306 has an input beam width 308 that is larger than necessary / optimal. For example, the input beam 306 may be slightly oversized out of the projector 106, may spread out before entering the optical waveguide 102, or because of some other reason. The input beam width 308 is formed of a nominal beam width 500 and an additional beam width 502. The nominal beam width 500 maybe considered as similar to the input beam width 308 of FIG. 4. It should be noted that the portion of the input beam 306 corresponding to the nominal beam width 500 may or may not be a center field-of-view portion of the input beam 306 (e.g., from the projector 106). In other words, the portion corresponding to the nominal beam width 500 may be a portion of the input beam 306 corresponding to any angle of the field-of-view.

[0046] Same as the above, the input beam 306 passes through the aperture 208, and hits the coupling-in portion 310. The coupling-in portion 310 is configured to reflect the input beam 306 such that it reflects off the major surfaces 200 at the beam angle 314, which may be the same as the facet angle 304. In this implementation, the coupling-in portion 310 extends between the major surfaces 200. For example, in many cases, it may be easier to form the coupling-in portion 310 to extend to both major surfaces 200. Furthermore, while the coupling-in portion 310 may be shortened to not reflect the additional beam width 502, that portion of the light would be lost. Doing so may be detrimental to performance. Accordingly, the input beam width 308 is reflected by the coupling-in portion 310.

[0047] Because the input beam 306 is configured to not fill the entire aperture (e.g., as in FIG.3), the mixer 402 is still used. The mixer 402 may have the mixer length 404 that is equal to the nominal beam width 500 divided by a cosine of the facet angle 304. The mixer length 404 corresponds to only one angle of the field-of-view of the input beam 306. As opposed to being at the midplane between the major surfaces 200; however, the mixer 402 is placed at an offset 504 from the midplane. The offset 504 (e.g., an amount or distance from the midplane) may be equal to the additional beam width 502 multiplied by the cosine of the facet angle 304.

[0048] By offsetting the mixer 402 from the midplane, the input beam width 308 may be used even though it is larger than optimal (e.g., the nominal beam width 500). Accordingly, all of the light from the projector 106 may be sent to the eye-box plane 300 while still filling the eye-box plane 300.Methods

[0049] FIGS. 6-8 illustrate respective example methods of configuring an optical waveguide for use in a near-eye display. The steps may be split, combined, or rearranged without departing from the scope of this disclosure.

[0050] FIG. 6 illustrates an example method 600 of configuring an optical waveguide for use in a near-eye display. At 602, a coupling-in portion is provided within an optical waveguide configured to receive an input beam of a near-eye display and cause the input beam to reflect between major surfaces of the optical waveguide at a beam angle relative to the major surfaces. For example, the optical waveguide 102 may be designed to include the coupling-in portion 310 configured to receive the input beam 306 and cause the input beam 306 to reflect between the major surfaces 200 at the beam angle 314.

[0051] At 604, a set of first facets is provided that is disposed between the major surfaces, wherein the first facets are planar, parallel, and partially reflective and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality of beams. For example, the optical waveguide 102 may be designed to include the set of first facets 202.

[0052] At 606, a set of second facets is provided that is disposed between the major surfaces, wherein the second facets are planar, parallel, partially reflective, non-parallel with the first facets, and disposed at a facet angle relative to the major surfaces and configured to receive the plurality of beams from the set of first facets and partially reflect the plurality of beams as a plurality’ of output beams out of the optical waveguide. For example, the optical waveguide 102 may’ be designed to include the set of second facets 204 disposed at the facet angle 304.

[0053] At 608, the beam angle and / or the facet angle are configured such that they are the same. For example, the beam angle 314 and / or the facet angle 304 may be configured such that they are the same.

[0054] FIG. 7 illustrates an example method 700 of configuring an optical waveguide for use in a near-eye display. At 702, a coupling-in portion is provided within an optical waveguide comprising a mirror configured to receive an input beam of a near-eye display and cause theinput beam to reflect between major surfaces of the optical waveguide at a beam angle relative to the major surfaces. For example, the optical waveguide 102 may be designed to include the coupling-in portion 310 (e.g., coupling-in mirror) configured to receive the input beam 306 and cause the input beam 306 to reflect between the major surfaces 200 at the beam angle 314.

[0055] At 704, a set of first facets is provided that is disposed between the major surfaces, wherein the first facets are planar, parallel, and partially reflective and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality of beams. For example, the optical waveguide 102 may be designed to include the set of first facets 202.

[0056] At 706, a set of second facets is provided that is disposed between the major surfaces, wherein the second facets are planar, parallel, partially reflective, non-parallel with the first facets, and disposed at a facet angle relative to the major surfaces and configured to receive the plurality' of beams from the set of first facets and partially reflect the plurality of beams as a plurality’ of output beams out of the optical waveguide. For example, the optical waveguide 102 may’ be designed to include the set of second facets 204 disposed at the facet angle 304.

[0057] At 708, a mirror length of the mirror is configured such that the mirror length multiplied by a cosine of a mirror angle of the mirror relative to the major surfaces is equal to an input beam width of the input beam. For example, the mirror length 400 may be configured such that the mirror length 400 multiplied by a cosine of the mirror angle 312 is equal to the input beam width 308.

[0058] FIG. 8 illustrates an example method 800 of configuring an optical waveguide for use in a near-eye display. At 802, a coupling-in portion is provided within an optical waveguide configured to receive an input beam of a near-eye display and cause the input beam to reflect between major surfaces of the optical waveguide at a beam angle relative to the major surfaces. For example, the optical waveguide 102 may be designed to include the coupling-in portion 310 configured to receive the input beam 306 and cause the input beam 306 to reflect between the major surfaces 200 at the beam angle 314.

[0059] . At 804, a set of first facets is provided that is disposed between the major surfaces, wherein the first facets are planar, parallel, and partially reflective and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality ofbeams. For example, the optical waveguide 102 may be designed to include the set of first facets 202.

[0060] At 806, a set of second facets is provided that is disposed between the major surfaces, wherein the second facets are planar, parallel, partially reflective, non-parallel with the first facets, and disposed at a facet angle relative to the major surfaces and configured to receive the plurality of beams from the set of first facets and partially reflect the plurality of beams as a plurality of output beams out of the optical waveguide. For example, the optical waveguide 102 may be designed to include the set of second facets 204 disposed at the facet angle 304.

[0061] At 808, a mixer is provided that is disposed between the coupling-in portion and the set of second facets, parallel to the major surfaces, and offset from a midplane between the major surfaces. For example, the mixer 402 may be disposed between the coupling-in portion 310 and the set of second facets 204. More specifically, the mixer 402 may be disposed between the set of first facets 202 and the set of second facets 204. The mixer 402 may include the offset 504 from a midplane between the major surfaces 200.

[0062] At 810, an amount of the offset is configured. For example, offset 504 may be configured. More specifically, the offset 504 may be set to be equal to the additional beam width 502 multiplied by the cosine of the facet angle 304.Examples

[0063] Example 1: A near-eye display comprising: a projector configured to produce an input beam; and an optical waveguide comprising: a pair of major surfaces that are parallel; a coupling-in portion configured to receive the input beam and cause the input beam to reflect between the major surfaces at a beam angle relative to the major surfaces; a set of first facets disposed between the major surfaces, wherein the first facets are planar, parallel, and partially reflective and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality of beams; and a set of second facets disposed between the major surfaces, wherein the second facets are planar, parallel, partially reflective, non-parallel with the first facets, and disposed at a facet angle relative to the major surfaces and configured to receive the plurality' of beams from the set of first facets and partially reflect the plurality ofbeams as a plurality of output beams out of the optical waveguide, wherein the beam angle and the facet angle are the same.

[0064] Example 2: The near-eye display of example 1, wherein: the coupling-in portion comprises a mirror; and a mirror length of the mirror multiplied by a cosine of a mirror angle of the mirror relative to the major surfaces is equal to an input beam width of the input beam.

[0065] Example 3: The near-eye display of example 1 or 2, wherein the coupling-in portion comprises a mirror that extends between the major surfaces.

[0066] Example 4: The near-eye display of any previous example, wherein a length of the second facets multiplied by a cosine of the facet angle is equal to an input beam width of the input beam.

[0067] Example 5: The near-eye display of any of examples 1 to 3, further comprising a mixer disposed between the coupling-in portion and the set of second facets and parallel to the major surfaces.

[0068] Example 6: The near-eye display of example 5, wherein the mixer is offset from a mi dp lane between the major surfaces.

[0069] Example 7: The near-eye display of example 5, wherein the mixer is disposed at a mi dp lane between the major surfaces.

[0070] Example 8: The near-eye display of any of examples 5 to 7, wherein the mixer has a length that is equal to an input beam width of the input beam divided by a cosine of the facet angle.

[0071] Example 9: The near-eye display of any of examples 5 to 8, wherein half a length of the second facets multiplied by a cosine of the facet angle is equal to an input beam width of the input beam.

[0072] Example 10: A method of configuring an optical waveguide for a near-eye display, the method comprising: providing for a coupling-in portion within the optical waveguide configured to receive an input beam of the near-eye display and cause the input beam to reflect between major surfaces of the optical waveguide at a beam angle relative to the major surfaces; providing for a set of first facets disposed between the major surfaces, wherein the first facets are planar, parallel, and partially reflective and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality of beams; providing for a set ofsecond facets disposed between the major surfaces, wherein the second facets are planar, parallel, partially reflective, non-parallel with the first facets, and disposed at a facet angle relative to the major surfaces and configured to receive the plurality of beams from the set of first facets and partially reflect the plurality of beams as a plurality of output beams out of the optical waveguide; and configuring the beam angle and the facet angle such that they are the same.

[0073] Example 11: A near-eye display comprising: a projector configured to produce an input beam; and an optical waveguide comprising: a pair of major surfaces that are parallel; couplingin portion comprising a mirror configured to receive the input beam and cause the input beam to reflect between the major surfaces at a beam angle relative to the major surfaces, wherein a mirror length of the mirror multiplied by a cosine of a mirror angle of the mirror relative to the major surfaces is equal to an input beam width of the input beam; a set of first facets disposed between the major surfaces, wherein the first facets are planar, parallel, partially reflective, and disposed at a facet angle relative to the major surfaces and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality' of beams; and a set of second facets disposed between the major surfaces, wherein the second facets are planar, parallel, partially reflective, and non-parallel with the first facets and configured to receive the plurality' of beams from the set of first facets and partially reflect the plurality of beams as a plurality of output beams out of the optical waveguide.

[0074] Example 12: The near-eye display of example 11, wherein the beam angle and the facet angle are the same.

[0075] Example 13: The near-eye display of example 11 or 12, wherein a length of the second facets multiplied by a cosine of the facet angle is equal to the input beam width,

[0076] Example 14: The near-eye display of example 11 or 12, further comprising a mixer disposed between the coupling-in portion and the set of second facets and parallel to the major surfaces.

[0077] Example 15: The near-eye display of example 14, wherein the mixer is disposed at a midplane between the major surfaces.

[0078] Example 16: The near-eye display of example 14 or 15, wherein the mixer has a length that is equal to the input beam width divided by a cosine of the facet angle.

[0079] Example 17: The near-eye display of any of examples 14 to 16, wherein the input beam width is equal to half a length of the second facets multiplied by a cosine of the facet angle.

[0080] Example 18: A method of configuring an optical waveguide for a near-eye display, the method comprising: providing for a coupling-in portion within the optical waveguide comprising a mirror configured to receive an input beam of the near-eye display and cause the input beam to reflect between major surfaces of the optical waveguide at a beam angle relative to the major surfaces, providing for a set of first facets disposed between the major surfaces, wherein the first facets are planar, parallel, and partially reflective and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality of beams; providing for a set of second facets disposed between the major surfaces, wherein the second facets are planar, parallel, partially reflective, non-parallel with the first facets, and disposed at a facet angle relative to the major surfaces and configured to receive the plurality of beams from the set of first facets and partially reflect the plurality of beams as a plurality of output beams out of the optical waveguide; and configuring a mirror length of the mirror such that the mirror length multiplied by a cosine of a mirror angle of the mirror relative to the major surfaces is equal to an input beam width of the input beam.

[0081] Example 19: A near-eye display comprising: a projector configured to produce an input beam; and an optical waveguide comprising: a pair of major surfaces that are parallel; a coupling-in portion configured to receive the input beam and cause the input beam to reflect between the major surfaces at a beam angle relative to the major surfaces; a set of first facets disposed between the major surfaces, wherein the first facets are planar, parallel, and partially reflective and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality of beams; a set of second facets disposed between the major surfaces, wherein the second facets are planar, parallel, partially reflective, non-parallel with the first facets, and disposed at a facet angle relative to the major surfaces and configured to receive the plurality of beams from the set of first facets and partially reflect the plurality of beams as a plurality of output beams out of the optical waveguide, wherein an input beam width of the input beam is larger than half a length of the second facets multiplied by a cosine of the facet angle; and a mixer disposed between the coupling-in portion and the set of second facets, parallel to the major surfaces, and offset from a midplane between the major surfaces.

[0082] Example 20: The near-eye display of example 19, wherein the beam angle and the facet angle are the same.

[0083] Example 21: The near-eye display of example 19 or 20, wherein the coupling-in portion comprises a mirror that extends between the major surfaces.

[0084] Example 22: The near-eye display of any of examples 19 to 21, wherein: a difference between the input beam width of the input beam and half the length of the second facets multiplied by the cosine of the facet angle is an additional beam width; and an amount of the offset is equal to the additional beam width multiplied by the cosine of the facet angle.

[0085] Example 23: The near-eye display of any of examples 19 to 22, wherein: a difference between the input beam width of the input beam and the additional beam width is a nominal beam width; and the mixer has a length that is equal to the nominal beam width divided by the cosine of the facet angle.

[0086] Example 24: The near-eye display of example 23, wherein a portion of the input beam corresponding to the nominal beam width corresponds to a center field-of-view portion of the input beam.

[0087] Example 25: The near-eye display of example 23, wherein a portion of the input beam corresponding to the nominal beam width corresponds to a non-center field-of-view portion of the input beam.

[0088] Example 26: The near-eye display of any of examples 19-25, wherein the mixer has a length that is equal to the input beam width divided by a cosine of the facet angle.

[0089] Example 27: The near-eye display of any of examples 19-26, wherein the mixer has a length that corresponds to an angle of a field-of-view of the input beam.

[0090] Example 28: A method of configuring an optical waveguide for a near-eye display, the method comprising: providing for a coupling-in portion within the optical waveguide configured to receive an input beam of the near-eye display and cause the input beam to reflect between major surfaces of the optical waveguide at a beam angle relative to the major surfaces; providing for a. set of first facets disposed between the major surfaces, wherein the first facets are planar, parallel, and partially reflective and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality of beams; providing for a set of second facets disposed between the major surfaces, wherein the second facets are planar,parallel, partially reflective, non-parallel with the first facets, and disposed at a facet angle relative to the major surfaces and configured to receive the plurality of beams from the set of first facets and partially reflect the plurality of beams as a plurality of output beams out of the optical waveguide; providing for a mixer disposed between the coupling-in portion and the set of second facets, parallel to the major surfaces, and offset from a midplane between the major surfaces; and configuring an amount of the offset.

[0091] Example 29: A method of configuring the near-eye display of any of examples 1-9, 11-17, and 19-27.

[0092] Example 30: Ey eglasses comprising the near-eye display of any of examples 1-9, 11-17, and 19-27.

[0093] Example 31: An optical waveguide configured for use in the near-eye display of any of examples 1-9, 11-17, and 19-27.Conclusion

[0094] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms “a,” “an” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms “includes,” “comprises” and / or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. Further, the terms up, upper, down, lower, above, below, left, right, forward, rearward, and the like are intended to be understood in the context of the representations described and illustrated above so that a wearable device may have such an orientation in reference to the frame or to various elements as supported by the frame or as illustrated in the drawing figures.

[0095] The corresponding structures, materials, acts, and equivalents of all means or step plus function elements, if any, in the claims below are intended to include any structure, material, or act for performing the function in combination with other claimed elements as specifically claimed. The description of the present invention has been presented for purposes of illustrationand description, but is not intended to be exhaustive or limited to the invention in the form disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the invention. The various embodiments were chosen and described in order to best explain the principles of the invention and the practical application, and to enable others of ordinary skill in the art to understand the invention for various embodiments with various modifications as are suited to the particular use contemplated.

Claims

CLAIMSWhat is claimed is:

1. A near-eye display comprising:a projector configured to produce an input beam; andan optical waveguide comprising:a pair of major surfaces that are parallel;a coupling-in portion configured to receive the input beam and cause the input beam to reflect between the major surfaces at a beam angle relative to the major surfaces;a set of first facets disposed between the major surfaces, wherein the first facets are planar, parallel, and partially reflective and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality of beams; anda set of second facets disposed between the major surfaces, wherein the second facets are planar, parallel, partially reflective, non-parallel with the first facets, and disposed at a facet angle relative to the major surfaces and configured to receive the plurality of beams from the set of first facets and partially reflect the plurality of beams as a plurality of output beams out of the optical waveguide,wherein the beam angle and the facet angle are the same.

2. The near-eye display of claim 1, wherein:the coupling-in portion comprises a mirror; anda mirror length of the mirror multiplied by a cosine of a mirror angle of the mirror relative to the major surfaces is equal to an input beam width of the input beam.

3. The near-eye display of claim 1, wherein the coupling-in portion comprises a mirror that extends between the major surfaces.

4. The near-eye display of claim 1, wherein a length of the second facets multiplied by a cosineof the facet angle is equal to an input beam width of the input beam.

5. The near-eye display of claim 1, further comprising a mixer disposed between the coupling-in portion and the set of second facets and parallel to the major surfaces.

6. The near-eye display of claim 5, wherein the mixer is offset from a midplane between the major surfaces.

7. The near-eye display of claim 5, wherein the mixer is disposed at a midplane between the major surfaces.

8. The near-eye display of claim 5, wherein the mixer has a length that is equal to an input beam width of the input beam divided by a cosine of the facet angle.

9. The near-eye display of claim 5, wherein half a length of the second facets multiplied by a cosine of the facet angle is equal to an input beam width of the input beam.

10. A method of configuring an optical waveguide for a near-eye display, the method comprising:providing for a coupling-in portion within the optical waveguide configured to receive an input beam of the near-eye display and cause the input beam to reflect between major surfaces of the optical waveguide at a beam angle relative to the major surfaces;providing for a set of first facets disposed between the major surfaces, wherein the first facets are planar, parallel, and partially reflective and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality of beams, providing for a set of second facets disposed between the major surfaces, wherein the second facets are planar, parallel, partially reflective, non-parallel with the first facets, and disposed at a facet angle relative to the major surfaces and configured to receive the plurality of beams from the set of first facets and partially reflect the plurality of beams as a plurality of output beams out of the optical waveguide; andconfiguring the beam angle and the facet angle such that they are the same.

11. A near-eye display comprising:a projector configured to produce an input beam; andan optical waveguide comprising:a pair of major surfaces that are parallel;a coupling-in portion comprising a mirror configured to receive the input beam and cause the input beam to reflect between the major surfaces at a beam angle relative to the major surfaces, wherein a mirror length of the mirror multiplied by a cosine of a mirror angle of the mirror relative to the major surfaces is equal to an input beam width of the input beam;a set of first facets disposed between the major surfaces, wherein the first facets are planar, parallel, partially reflective, and disposed at a facet angle relative to the major surfaces and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality of beams; anda set of second facets disposed between the major surfaces, wherein the second facets are planar, parallel, partially reflective, and non-parallel with the first facets and configured to receive the plurality of beams from the set of first facets and partially reflect the plurality of beams as a plurality of output beams out of the optical waveguide.

12. The near-eye display of claim 11, wherein the beam angle and the facet angle are the same.

13. The near-eye display of claim 11, wherein a length of the second facets multiplied by a cosine of the facet angle is equal to the input beam width.

14. The near-eye display of claim 11, further comprising a mixer disposed between the couplingin portion and the set of second facets and parallel to the major surfaces.

15. The near-eye display of claim 14, wherein the mixer is disposed at a midplane between the major surfaces.

16. The near-eye display of claim 14, wherein the mixer has a length that is equal to the input beam width divided by a cosine of the facet angle.

17. The near-eye display of claim 14, wherein the input beam width is equal to half a length of the second facets multiplied by a cosine of the facet angle.

18. A method of configuring an optical waveguide for a near-eye display, the method comprising:providing for a coupling-in portion within the optical waveguide comprising a mirror configured to receive an input beam of the near-eye display and cause the input beam to reflect between major surfaces of the optical waveguide at a beam angle relative to the major surfaces, providing for a set of first facets disposed between the major surfaces, wherein the first facets are planar, parallel, and partially reflective and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality of beams;providing for a set of second facets disposed between the major surfaces, wherein the second facets are planar, parallel, partially reflective, non-parallel with the first facets, and disposed at a facet angle relative to the major surfaces and configured to receive the plurality of beams from the set of first facets and partially reflect the plurality of beams as a plurality of output beams out of the optical waveguide; andconfiguring a mirror length of the mirror such that the mirror length multiplied by a cosine of a mirror angle of the mirror relative to the major surfaces is equal to an input beam width of the input beam.

19. A near-eye display comprising:a projector configured to produce an input beam; andan optical waveguide comprising:a pair of major surfaces that are parallel,a coupling-in portion configured to receive the input beam and cause the input beam to reflect between the major surfaces at a beam angle relative to the major surfaces;a set of first facets disposed between the major surfaces, wherein the first facets are planar, parallel, and partially reflective and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality of beams;a set of second facets disposed between the major surfaces, wherein the second facets are planar, parallel, partially reflective, non-parallel with the first facets, and disposed at a facet angle relative to the major surfaces and configured to receive the plurality of beams from the set of first facets and partially reflect the plurality of beams as a plurality of output beams out of the optical waveguide, wherein an input beam width of the input beam is larger than half a length of the second facets multiplied by a cosine of the facet angle; anda mixer disposed between the coupling-in portion and the set of second facets, parallel to the major surfaces, and offset from a midplane between the major surfaces.

20. The near-eye display of claim 19, wherein the beam angle and the facet angle are the same.

21. The near-eye display of claim 19, wherein the coupling-in portion comprises a mirror that extends between the major surfaces.

22. The near-eye display of claim 19, wherein:a difference between the input beam width of the input beam and half the length of the second facets multiplied by the cosine of the facet angle is an additional beam width; andan amount of the offset is equal to the additional beam width multiplied by the cosine of the facet angle,23. The near-eye display of claim 22, wherein:a difference between the input beam width of the input beam and the additional beam width is a nominal beam width; andthe mixer has a length that is equal to the nominal beam width divided by the cosine of the facet angle.

24. The near-eye display of claim 19, wherein the mixer has a length that is equal to the input beam width divided by a cosine of the facet angle.

25. A method of configuring an optical waveguide for a near-eye display, the method comprising:providing for a coupling-in portion within the optical waveguide configured to receive an input beam of the near-eye display and cause the input beam to reflect between major surfaces of the optical waveguide at a beam angle relative to the major surfaces;providing for a set of first facets disposed between the major surfaces, wherein the first facets are planar, parallel, and partially reflective and are configured to receive the input beam from the coupling-in portion and partially reflect the input beam as a plurality of beams;providing for a set of second facets disposed between the major surfaces, wherein the second facets are planar, parallel, partially reflective, non-parallel with the first facets, and disposed at a facet angle relative to the major surfaces and configured to receive the plurality of beams from the set of first facets and partially reflect the plurality of beams as a plurality of output beams out of the optical waveguide;providing for a mixer disposed between the coupling-in portion and the set of second facets, parallel to the major surfaces, and offset from a midplane between the major surfaces; and configuring an amount of the offset.

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