Waveguide assembly

Abstract

A waveguide assembly is disclosed. The waveguide assembly comprises a first waveguide slab and a second waveguide slab. The first waveguide slab is arranged to receive image-bearing light and enlarge a pupil size of the image-bearing light parallel to a first axis. The first waveguide slab comprises a first input coupling device arranged to couple image-bearing light into the first waveguide slab under total internal reflection (TIR), and a first out-coupling region arranged to decouple image-bearing light out of the first waveguide slab by means of reflection. The second waveguide slab is arranged to couple at least a portion of the out-coupled image-bearing light from the first waveguide slab into the second waveguide slab and enlarge the pupil size parallel to a second axis, the second axis substantially orthogonal to the first axis. The second waveguide slab comprises a diffractive in-coupling region and a transmissive diffractive out-coupling region, through which a user can view real world imagery and the out-coupled image-bearing light simultaneously.

Description

(19) *EP004730011A2* (11) EP 4 730 011 A2 (12) EUROPEAN PATENT APPLICATION (43) Date of publication: 22.04.2026 Bulletin 2026 / 17 (21) Application number: 26153313.7 (22) Date of filing: 08.09.2021 (51) International Patent Classification (IPC): G02B 27 / 00 (2006.01) (52) Cooperative Patent Classification (CPC): G02B 27 / 0172; G02B 27 / 0081 (84) Designated Contracting States: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR (30) Priority: 28.09.2020 EP 20275151 28.09.2020 GB 202015292 (62) Document number(s) of the earlier application(s) in accordance with Art. 76 EPC: 21770059.0 / 4 217 652 (71) Applicant: Snap Inc. Santa Monica, California 90405 (US) (72) Inventors: • MILLS, Rory Thomas Alexander Santa Monica, 90405 (US) • MACKEN, Ian Thomas deceased (GB) (74) Representative: Gill Jennings & Every LLP The Broadgate Tower 20 Primrose Street London EC2A 2ES (GB) Remarks: This application was filed on 21‑01‑2026 as a divisional application to the application mentioned under INID code 62. (54) WAVEGUIDE ASSEMBLY (57) A waveguide assembly is disclosed. The wave- guide assembly comprises a first waveguide slab and a second waveguide slab. The first waveguide slab is ar- ranged to receive image-bearing light and enlarge a pupil size of the image-bearing light parallel to a first axis. The first waveguide slab comprises a first input coupling device arranged to couple image-bearing light into the first waveguide slab under total internal reflection (TIR), and a first out-coupling region arranged to decouple image-bearing light out of the first waveguide slab by means of reflection. The second waveguide slab is ar- ranged to couple at least a portion of the out-coupled image-bearing light from the first waveguide slab into the second waveguide slab and enlarge the pupil size par- allel to a second axis, the second axis substantially orthogonal to the first axis. The second waveguide slab comprises a diffractive in-coupling region and a trans- missive diffractive out-coupling region, through which a user can view real world imagery and the out-coupled image-bearing light simultaneously. EP 4 73 0 01 1 A 2 Processed by Luminess, 75001 PARIS (FR) 2 1 EP 4 730 011 A2 2 Description BACKGROUND

[0001] It is desirable, for augmented reality applica- tions, for the field of view of the display to be large. Due to the variation in users’ physical features it is also desirable for the display to encompass a large exit pupil to allow for generic fitment of the displays and allow for movement of the users eyes with respect to the display surface. In order to reduce the overall size of the optics used to display the images, whilst providing a large FOVand exit pupil, pupil expansion techniques are used. BRIEF DESCRIPTION OF DRAWINGS

[0002] Figure 1 illustrates a waveguide configured to ex- pand an image-bearing pupil in a single dimension. Figure 2a is an expanded illustration of a waveguide assembly to expand an image-bearing pupil in two dimensions. Figure 2b is an illustration of a waveguide assembly to expandan image-bearing pupil in twodimensions. Figure 3a illustrates a single waveguide, with a fixed pitch grating, with red light coupled into the wave- guide. Figure 3b illustrates the same single waveguide as figure 3a with the same fixed pitch grating, with blue light coupled into the waveguide. Figure 4 illustrates a pupil expander that utilizes reflective coupling elements rather than diffractive elements. Figure 5a illustrates a side-on view of a reflective waveguide slab. Figure 5b illustrates a top-down view of a reflective waveguide slab. Figure 5c illustrates a top-down view of a transmis- sive waveguide slab. Figure 5d illustrates a side-on view of a transmissive waveguide slab. Figure 6 illustrates a co-planar waveguide arrange- ment comprising 3 waveguide slabs. Figure 7a illustrates a single ray under TIR in a waveguide. Figure 7b illustrates the single ray coupled out of the waveguide. Figure 8a illustrates a single ray confined in a wa- veguide comprising two waveguide slabs bonded together. Figure 8b illustrates the single ray output from the waveguide comprising twowaveguide slabs bonded together. Figure 9 illustrates a binocular arrangement. Figure 10 illustrates an alternative binocular ar- rangement. DETAILED DESCRIPTION

[0003] Pupil expansion can be achieved using a wa- veguide 100 comprising a diffraction grating, as illu- strated in Figure 1. The waveguide 100 comprises an input grating 110 and an output grating 120. The output grating is configured to output light out of the waveguide and expand light in a single dimension. A grating is a periodic structure that may splits and diffracts light into different directions. The periodic structures are often known as lines, and shall be referred to as such through- out the description.

[0004] Expansion in two dimensions can be achieved using two orthogonal waveguides, as illustrated in Figure 2. The grating lines on each waveguide are substantially orthogonal toeachother.An input pupil is coupled into the first waveguide 100a using input grating 110a. The input pupil is expanded within and out coupled from the wa- veguide 100a by the output grating 120a.

[0005] The second waveguide 100b is arranged such that the grating lines of the second expansion grating 120b are substantially orthogonal to the grating lines of the first expansion grating 120aand such that light output from the first waveguide by the output grating 120a is coupled into the second waveguide 100b by the input grating 110b. The output grating 120b of the second waveguide 100b is used to expand the pupil in a second direction orthogonal to the first direction and to output the light form the second waveguide.

[0006] The arrangement as shown in Figures 2a and 2b is inefficient due to the use of low efficiency gratings used to perform the cross-coupling between the first and the second waveguides. As the arrangement in Figures 2a and 2b uses diffraction gratings it also has inherent fieldof view (FOV)andwavelengthbandwidth limitations.

[0007] For a single diffractive waveguide, with a fixed pitch input grating, it is difficult to couple a large wave- length range over a large FOV, due to the diffracted angles for certain wavelengths falling outside the TIR conditions of the glass substrate.

[0008] Therefore for a wide FOV image comprising multiple wavelengths (i.e. full colour) multiple stacked waveguides are normally required for both the horizontal expander and vertical expander with this setup. A single waveguide with fixed pitch input grating is shown in Figure 3a. When red light is input, as shown in Figure 3a, the full redFOV is coupled under TIR.However, when blue light is input, as shown in Figure 3b, the blue FOV is mostly ejected as the FOV is not coupled as it cannot be constrained by TIR.

[0009] An alternative is to utilise a pupil expander that utilizes reflective coupling elements rather than diffrac- tive elements. This is illustrated in Figure 4.

[0010] A waveguide comprising a reflective or trans- missive input coupling device such as a prism does not have the same chromatic constraints as a diffraction grating and multiple wavelengths can be coupled over a larger FOV. Therefore a single waveguide can be used 5 10 15 20 25 30 35 40 45 50 55 3 3 EP 4 730 011 A2 4 to constrain a full colour, wide FOV image under TIR, in contrast to the arrangement of Figures 3a and 3b. A reflectiveoutput structureattached to thewaveguide slab can also output the waveguided light in a more efficient way than a typical diffractive grating.

[0011] A reflective output coupler used solely for pupil expansion (i.e. in the case of a horizontal expander) does not have a requirement to be transmissive / see-through so can be coated for high reflection (high efficiencymirror coating), with a graded efficiency to yield a uniform out- put.

[0012] Optimising a reflective out coupling structure to maintain a clear see-through path with minimised arte- factswithin the visual field canbedifficult due to theuseof multiple reflective surfaces within the line of sight. In comparison typical diffractive out coupling structures can be optimised to be highly see-through with minimal artefacts, especially when embedded within a glass sub- strate since the nanometre sized diffractive structures used are unperceivable by the human eye.

[0013] Therefore combining a reflective pupil expan- derwith a diffractive pupil expander can yield a combined two dimensional pupil expander which comprises the best qualities of both technologies.

[0014] A waveguide assembly 500 according to some examples is described with reference to Figures 5a-d. Waveguide assembly 500 comprises a first waveguide 10 slab 500a and a second waveguide slab 500b.

[0015] The first waveguide slab 500a is arranged to receive image-bearing light, and enlarge the pupil of the image bearing light parallel to a first axis. The first wa- veguide slab 500a comprises a first input coupling device 510aarranged to couple light into thefirstwaveguide slab under total internal reflection (TIR). The first waveguide slab 500a also comprises a first output coupling region 520a, arranged to expand the pupil in a direction parallel to a first axis by means of reflection. The first output coupling region 520a also is arranged to couple the image-bearing light out of the first waveguide slab 500a.

[0016] The first waveguide slab 500a is illustrated in a side-on view in Figure 5a, 20 and a top-down view in Figure 5b.

[0017] Thesecondwaveguide slab500b is arranged to couple at least a portion of the out-coupled light from the first waveguide slab 500a into the second waveguide slab 500b, and to expand the image-bearing light in a direction substantially parallel to a second axis. The second axis is substantially orthogonal to the first axis.

[0018] The second waveguide slab 500b comprises a diffractive in-coupling region 510b and a transmissive diffractive out-coupling region 520b, through which a user can view real world imagery and the out-coupled image-bearing light simultaneously.

[0019] The second waveguide slab 500b is illustrated in a top-down view in Figure 5c, and a side-on view in Figure 5d.

[0020] The first waveguide slab 500a comprising the first output coupling region 520a using reflective technol- ogy can carry a large FOV and spectral range within a single slab arrangement. The first waveguide slab 500a comprising the first output coupling region 520a can be optimised to be highly efficient and graded for uniformity without the requirement to be see-through.

[0021] In someexamples grading can be performedby varying the size, shape and spacing of the structures, preferably non-linearly.

[0022] In some examples the height or depth (e.g. 10’s um to100’sum)of thegratingmaybevaried, preferably in the range of 10’s µm to 100’s µm.

[0023] In some examples the spacing between adja- cent features may be varied, preferably in the range of 10’s µm to 1000’s µm. (e.g. 10’s um to 1000’s um).

[0024] In some examples the angles of the blaze face may be varied, preferably in the range of 20deg to 35deg.

[0025] Gradients of features may be optimised to yield the best output uniformity for a certain setup e.g. depen- dent upon FOV and output area required.

[0026] The second waveguide slab 500b using diffrac- tive technology can be optimised to be highly see- through with minimal see-through artefacts, whilst ex- panding the vertical pupil over a large area.

[0027] In someexamples the first input couplingdevice 510a is attached to the outside of the first waveguide slab 500a. This may allow the first input coupling device 510a to be manufactured separately and bonded or glued to the outside of the first waveguide slab 500a.

[0028] In someexamples the first input couplingdevice 510amaycompriseaprismaticdevice, suchasaprismor a plurality of prisms. A prismatic input device may be optimised to in-couple awide rangeofwavelengths anda large FOV.

[0029] In some examples the image-bearing light may be decoupled uniformly across the first out-coupling re- gion 520a.

[0030] In some examples at least one of the first wa- veguide slab 500a and the second waveguide slab 500b may be curved and / or non-planar.

[0031] As the user is not required to look through the first waveguide slab 500a, the first waveguide slab 500a or the first output coupling region 520a may be substan- tially reflective and / or non transmissive.

[0032] To cater for a wider FOV with multiple wave- lengths multiple waveguide slabs similar to second wa- veguide slab 500b can be used in a co-planar waveguide assembly 600. This is illustrated in Figure 6. Multiple wavelength waveguide assembly comprises a horizontal waveguide slab 610, a first vertical waveguide slab 620 and a second vertical waveguide slab 630. Horizontal waveguide slab 610 is substantially similar to first wave- guide slab 510, and comprises an output coupling region (not shown in Figure 6), arranged to expand the pupil in a direction parallel to a first axis bymeans of reflection. The output coupling region also is arranged to couple the image-bearing light out of the horizontal waveguide slab 610 towards the first vertical waveguide slab 620 and the second waveguide slab 630. 5 10 15 20 25 30 35 40 45 50 55 4 5 EP 4 730 011 A2 6

[0033] The horizontal waveguide slab 610 is arranged to expand the pupil parallel to a first axis. The first vertical waveguide slab 620 and the second vertical waveguide slab 630 are arranged co-planar to the horizontal wave- guide slab 610 and are arranged to expand the pupil parallel to a second axis, wherein the second axis is substantially orthogonal to the first axis. The first vertical waveguide slab 620 and the second vertical waveguide slab 630 are offset along a third axis, offset by a minimal gap. The first and second vertical waveguide slabs are substantially similar to the second waveguide slab 500b.

[0034] The gap may comprise an air gap, or may be filled with a material such as an optical glue.

[0035] In the co-planar waveguide assembly 600 the FOV is effectively split upon ejection from the horizontal waveguide slab 610, due to the optical path undertaken within the horizontal waveguide slab 610. The two ver- tical waveguide slabs can be arranged to only receive a portion of this FOV and couple it into the respective waveguides. The grating pitch of the two in-coupling gratings on the vertical waveguide slabs will likely be different, as differing grating pitches can be used to optimise coupling efficiency of the differing portions of FOV.

[0036] The co-planar waveguide assembly 600 may also comprise more than two vertical waveguide slabs.

[0037] In some examples at least one of the horizontal waveguide slab 610, first vertical waveguide slab 620 and the second vertical waveguide slab 630 may be curved and / or non-planar.

[0038] In some examples at least one of the first wa- veguide slab 500a and the second waveguide slab 500b may be formed from one or more substrates 10 bonded together. Optical coatings may be included between these bonded substrates.

[0039] In some examples the optical coatingmay com- prise a beam splitting coating. A beam splitting coating splits light into a transmitted and reflected component. Beamsplitting coatings are typically formed from low and high index dielectricmaterials (e.g.MgF2, SiO2, TiO2) or metallic materials (e.g. Al, Ag).

[0040] If the beam splitting coating is placed between substratesor slabsofnon-equal thickness (e.g. substrate 1 is 1mm thick and substrate 2 is 2mm thick) then the rays start to get split multiple times resulting in many genera- tions of rays being generated from a single source ray. This is illustrated in Figures 7a-b and 8a-b.

[0041] In Figure 7a a single ray propagates along the waveguide slab under TIR. When the ray is output from the waveguide slab, as shown in Figure 7b, there are gaps between the output rays.

[0042] In Figure 8a two waveguide slabs of different thickness are bonded together using a beam splitting coating. The single ray interacts with the beam splitting coating, and is split into a transmitted beam and a re- flected beam. The subsequent reflected and transmitted beams also interact with the beam splitting coating. This process is repeated multiple times.

[0043] When the light is emitted from the waveguide slab, as shown in Figure 8b, the gaps between the pupils are reduced in comparison to the example of Figure 7b.

[0044] Figure 6 illustrates light passing through first vertical waveguide slab 620 before being input into sec- ond vertical waveguide slab 630. However, in some ex- amples light input into second vertical waveguide slab 630maybe input into the secondwaveguide slab 630 in a direct optical path from the horizontal waveguide slab 610. A direct optical path refers to the fact that the light does not interact with other elements before being input into the second vertical waveguide slab 630. The light may subsequently interact with the first vertical wave- guide 620, for example if the firstwaveguide slab 620and the second waveguide slab are bonded together as described with relation to Figures 8a and 8b.

[0045] Multiple separate waveguide assemblies may be used to provide a binocular assembly, as illustrated in Figures 9 and 10. In the arrangement shown in Figure 9 the reflective waveguide slabs are arranged above the eyes of the user. In an alternative arrangement shown in Figure 10 the reflective waveguide slabs are arranged to the side of the user’s eyes.

[0046] In some examples the arrangements shown in Figures 9 and 10 may be used as augmented reality glasses. In some examples the arrangements shown in Figures 9 and 10 may be used in a head mounted display or head up display.

[0047] Some preferred aspects of the present disclo- sure are set out in the following numbered clauses: Clause 1. A waveguide assembly comprising: a first waveguide slab, arranged to receive im- age-bearing light and enlarge a pupil size of the image-bearing light parallel toafirst axis, thefirst waveguide slab comprising a first input coupling device arranged to couple image-bearing light into the first waveguide slab under total internal reflection (TIR), and a first out-coupling region arranged to decouple image-bearing light out of the first waveguide slab by means of reflection; a secondwaveguide slab, arranged to couple at least a portion of the out-coupled image-bearing light from the first waveguide slab into the sec- ond waveguide slab and enlarge the pupil size parallel to a second axis, the second axis sub- stantially orthogonal to the first axis; wherein the second waveguide slab comprises a diffrac- tive in-coupling region and a transmissive dif- fractive out-coupling region, through which a user can view real world imagery and the out- coupled image-bearing light simultaneously. Clause 2. The waveguide assembly according to Clause 1, wherein the first out-coupling region is attached to an outer surface of the first waveguide slab. 5 10 15 20 25 30 35 40 45 50 55 5 7 EP 4 730 011 A2 8 Clause3. Thewaveguideassemblyaccording toany of Clauses 1 or 2, wherein the image-bearing light is decoupled uniformly across the out-coupling region. Clause4. Thewaveguideassemblyaccording toany preceding Clause, wherein the first input coupling device comprises a prismatic device. Clause5. Thewaveguideassemblyaccording toany preceding Clause, wherein the first out-coupling re- gion is substantially fully reflective and / or non-trans- missive. Clause6. Thewaveguideassemblyaccording toany preceding Clause, further comprising a third wave- guide slab arranged to couple, under TIR into the third waveguide slab, image-bearing light from the first waveguide slab not coupled into the second waveguide slab and wherein the third waveguide slab comprises a transmissive diffractive out-cou- pling region, through which a user can view real world imagery and the out-coupled image-bearing light simultaneously. Clause 7. The waveguide assembly according to Clause 6, wherein light coupled into the third wave- guide slab does not interact with the second wave- guide slab before being input into the second wave- guide. Clause 8. The waveguide assembly according to Clause 6 or 7, wherein the in-coupling region of the second waveguide slab and the in-coupling re- gion of the third waveguide slab have different grat- ing pitch size. Clause9. Thewaveguideassemblyaccording toany of Clauses 6 to 8 wherein the third waveguide slab is coplanar with the second waveguide slab in the first axis and second axis and offset in a third axis, the third axis orthogonal to the first axis and the second axis. Clause 10. The waveguide assembly according to anyofClauses6 to9,wherein thesecondwaveguide slab and the third waveguide slab are bonded to- gether. Clause 11. The waveguide assembly according to Clause 10, wherein the second waveguide slab and the third waveguide slab are different thicknesses. Clause 12. The waveguide assembly according to any preceding Clause, wherein the second wave- guide is curved and / or non-planar. Clause 13. The waveguide assembly according to any preceding Clause, wherein the first waveguide slab is arranged to receive collimated image-bearing light. Clause 14. The waveguide assembly according to any preceding Clause, further comprising a collimat- ing device to output a collimated exit pupil received by the first waveguide. Clause 15. A binocular arrangement comprising a first waveguide assembly according to any of Clauses 1 to 14, to provide a first image to a user’s eye, andasecondwaveguideassemblyaccording to any of Clauses 1 to 14, to provide a second image to a user’s eye. Clause 16. Augmented reality glasses comprising a binocular assembly according to Clause 15. Clause 17. A head mounted display or head up dis- play comprising awaveguide assembly according to any of Clauses 1 to 14. Claims 1. A waveguide assembly comprising: a first waveguide slab, arranged to receive im- age-bearing light and enlarge a pupil size of the image-bearing light parallel toafirst axis, thefirst waveguide slab comprising a reflective in-cou- pling region arranged to couple image-bearing light into the first waveguide slab under total internal reflection (TIR), and a reflective out- coupling region on a same side of the first wa- veguide slab as the reflective in-coupling region and arranged to decouple image-bearing light out of the first waveguide slab by means of reflection; and a secondwaveguide slab, arranged to couple at least a portion of the out-coupled image-bearing light from the first waveguide slab into the sec- ond waveguide slab and enlarge the pupil size parallel to a second axis, the second axis sub- stantially orthogonal to the first axis; wherein the second waveguide slab comprises a diffractive in-coupling region on a surface of the second waveguide slab and a transmissive diffractive out-coupling region embedded within the second waveguide slab, through which a user can view real world imagery and the out- coupled image-bearing light simultaneously. 2. The waveguide assembly according to claim 1, wherein the side of the first waveguide slab to which the reflective in-coupling region and the reflective out-coupling region are attached is an outer surface of the first waveguide slab. 5 10 15 20 25 30 35 40 45 50 55 6 9 EP 4 730 011 A2 10 3. The waveguide assembly according to any preced- ing claim, wherein the image-bearing light is de- coupled uniformly across the reflective out-coupling region. 4. The waveguide assembly according to any preced- ing claim, wherein the first input coupling region comprises a prismatic device. 5. The waveguide assembly according to any preced- ing claim, wherein the reflective out-coupling region is substantially fully reflective and / or non-transmis- sive. 6. The waveguide assembly according to any preced- ing claim, further comprising: a third waveguide slab arranged to couple, un- der TIR into the third waveguide slab, image- bearing light from the first waveguide slab that is not coupled into the second waveguide slab, wherein the third waveguide slab comprises a transmissive diffractive out-coupling region, through which the user can view the real world imagery and the out-coupled image-bearing light simultaneously, thesecondwaveguide slab being between the first and third waveguide slabs in a coplanar waveguide arrangement; and wherein light coupled into the third waveguide slab is input into the third waveguide slab in a direct optical path from the first waveguide slab which does not pass through the second wave- guide slab, such that the light does not interact with the second waveguide slab before being input into the second waveguide slab, wherein the diffractive in-coupling region of the second waveguide slab and an in-coupling re- gion of the third waveguide slab have different grating pitch size. 7. The waveguide assembly according to claim 6, wherein the third waveguide slab is coplanar with the second waveguide slab in the first axis and the second axis and offset in a third axis, the third axis orthogonal to the first axis and the second axis. 8. The waveguide assembly according to claim 7, wherein the second waveguide slab and the third waveguide slab are bonded together. 9. The waveguide assembly according to claim 8, wherein the second waveguide slab and the third waveguide slab are different thicknesses. 10. The waveguide assembly according to any preced- ing claim, wherein at least one of the first waveguide slaband the secondwaveguide slab is curvedand / or non-planar. 11. The waveguide assembly according to any preced- ing claim, wherein the first waveguide slab is ar- ranged to receive collimated image-bearing light. 12. The waveguide assembly according to any preced- ing claim, further comprising: a collimating device to output a collimated exit pupil received by the first waveguide slab. 13. A binocular arrangement comprising a first wave- guide assembly according to any of claims 1 to 12, to provide a first image to a user’s eye, and a second waveguide assembly according to any of claims 1 to 12, to provide a second image to the user’s eye. 14. Augmented reality glasses comprising a binocular assembly according to claim 13. 15. Aheadmounted display or head up display compris- ingawaveguideassemblyaccording toanyof claims 1 to 12. 5 10 15 20 25 30 35 40 45 50 55 7 EP 4 730 011 A2 8 EP 4 730 011 A2 9 EP 4 730 011 A2 10 EP 4 730 011 A2 11 EP 4 730 011 A2 12 EP 4 730 011 A2 13 EP 4 730 011 A2 14 EP 4 730 011 A2 (19) *EP004730011A3* (11) EP 4 730 011 A3 (12) EUROPEAN PATENT APPLICATION (88) Date of publication A3: 01.07.2026 Bulletin 2026 / 27 (43) Date of publication A2: 22.04.2026 Bulletin 2026 / 17 (21) Application number: 26153313.7 (22) Date of filing: 08.09.2021 (51) International Patent Classification (IPC): G02B 27 / 01 (2006.01) G02B 27 / 00 (2006.01) (52) Cooperative Patent Classification (CPC): G02B 27 / 0172; G02B 27 / 0081 (84) Designated Contracting States: AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR (30) Priority: 28.09.2020 EP 20275151 28.09.2020 GB 202015292 (62) Document number(s) of the earlier application(s) in accordance with Art. 76 EPC: 21770059.0 / 4 217 652 (71) Applicant: Snap Inc. Santa Monica, California 90405 (US) (72) Inventors: • MILLS, Rory Thomas Alexander Santa Monica, 90405 (US) • MACKEN, Ian Thomas deceased (GB) (74) Representative: Mathys & Squire 32 London Bridge Street The Shard London SE1 9SG (GB) (54) WAVEGUIDE ASSEMBLY (57) A waveguide assembly is disclosed. The wave- guide assembly comprises a first waveguide slab and a second waveguide slab. The first waveguide slab is ar- ranged to receive image-bearing light and enlarge a pupil size of the image-bearing light parallel to a first axis. The first waveguide slab comprises a first input coupling device arranged to couple image-bearing light into the first waveguide slab under total internal reflection (TIR), and a first out-coupling region arranged to decouple image-bearing light out of the first waveguide slab by means of reflection. The second waveguide slab is ar- ranged to couple at least a portion of the out-coupled image-bearing light from the first waveguide slab into the second waveguide slab and enlarge the pupil size par- allel to a second axis, the second axis substantially orthogonal to the first axis. The second waveguide slab comprises a diffractive in-coupling region and a trans- missive diffractive out-coupling region, through which a user can view real world imagery and the out-coupled image-bearing light simultaneously. EP 4 73 0 01 1 A 3 Processed by Luminess, 75001 PARIS (FR) 2 EP 4 730 011 A3 5 10 15 20 25 30 35 40 45 50 55 3 EP 4 730 011 A3 5 10 15 20 25 30 35 40 45 50 55 4 EP 4 730 011 A3 5 10 15 20 25 30 35 40 45 50 55 摘要 公开了一种波导组件。所述波导组件包括第一波导板和第二波导板。所述第一波导板设 置为接收载像光并且沿平行于第一轴线的方向扩大所述载像光的光瞳尺寸。所述第一 波导板包括：第一输入耦合器件，其设置为将载像光耦至第一波导板中以进行全内反射 （TIR）；第一耦出区，其设置为通过反射方式将载像光从所述第一波导板解耦输出。所述 第二波导板设置为将从所述第一波导板耦出的载像光中的至少一部分耦合至所述第二 波导板内，并沿平行于第二轴线方向扩大所述光瞳尺寸，其中，所述第二轴线与所述第 一轴线基本正交。所述第二波导板包括衍射耦入区和透射式衍射耦出区，用户可通过衍 射耦入区和透射式衍射耦出区同时观看实景图像和所述耦出的载像光。

Claims

1. A waveguide assembly comprising: a first waveguide slab, arranged to receive image-bearing light and enlarge a pupil size of the image-bearing light parallel to a first axis, the first waveguide slab comprising a reflective in-coupling region arranged to couple image-bearing light into the first waveguide slab under total internal reflection (TIR), and a reflective out-coupling region on a same side of the first waveguide slab as the reflective in-coupling region and arranged to decouple image-bearing light out of the first waveguide slab by means of reflection; and a second waveguide slab, arranged to couple at least a portion of the out-coupled image-bearing light from the first waveguide slab into the second waveguide slab and enlarge the pupil size parallel to a second axis, the second axis substantially orthogonal to the first axis; wherein the second waveguide slab comprises a diffractive in-coupling region on a surface of the second waveguide slab and a transmissive diffractive out-coupling region embedded within the second waveguide slab, through which a user can view real world imagery and the out-coupled image-bearing light simultaneously.

2. The waveguide assembly according to claim 1, wherein the side of the first waveguide slab to which the reflective in-coupling region and the reflective out-coupling region are attached is an outer surface of the first waveguide slab.

3. The waveguide assembly according to any preceding claim, wherein the image-bearing light is decoupled uniformly across the reflective out-coupling region.

4. The waveguide assembly according to any preceding claim, wherein the first input coupling region comprises a prismatic device.

5. The waveguide assembly according to any preceding claim, wherein the reflective out-coupling region is substantially fully reflective and / or non-transmissive.

6. The waveguide assembly according to any preceding claim, further comprising: a third waveguide slab arranged to couple, under TIR into the third waveguide slab, image-bearing light from the first waveguide slab that is not coupled into the second waveguide slab, wherein the third waveguide slab comprises a transmissive diffractive out-coupling region, through which the user can view the real world imagery and the out-coupled image-bearing light simultaneously, the second waveguide slab being between the first and third waveguide slabs in a coplanar waveguide arrangement; and wherein light coupled into the third waveguide slab is input into the third waveguide slab in a direct optical path from the first waveguide slab which does not pass through the second waveguide slab, such that the light does not interact with the second waveguide slab before being input into the second waveguide slab, wherein the diffractive in-coupling region of the second waveguide slab and an in-coupling region of the third waveguide slab have different grating pitch size.

7. The waveguide assembly according to claim 6, wherein the third waveguide slab is coplanar with the second waveguide slab in the first axis and the second axis and offset in a third axis, the third axis orthogonal to the first axis and the second axis.

8. The waveguide assembly according to claim 7, wherein the second waveguide slab and the third waveguide slab are bonded together.

9. The waveguide assembly according to claim 8, wherein the second waveguide slab and the third waveguide slab are different thicknesses.

10. The waveguide assembly according to any preceding claim, wherein at least one of the first waveguide slab and the second waveguide slab is curved and / or non-planar.

11. The waveguide assembly according to any preceding claim, wherein the first waveguide slab is arranged to receive collimated image-bearing light.

12. The waveguide assembly according to any preceding claim, further comprising: a collimating device to output a collimated exit pupil received by the first waveguide slab.

13. A binocular arrangement comprising a first waveguide assembly according to any of claims 1 to 12, to provide a first image to a user's eye, and a second waveguide assembly according to any of claims 1 to 12, to provide a second image to the user's eye.

14. Augmented reality glasses comprising a binocular assembly according to claim 13.

15. A head mounted display or head up display comprising a waveguide assembly according to any of claims 1 to 12.

Images