Tapered anti-reflective coating maintains image sharpness in waveguide combiners.

Abstract

Embodiments of the disclosure provided herein include waveguide combiners. More specifically, embodiments described herein provide waveguide combiners having waveguide layers and coatings having tapered portions disposed thereon. Waveguides include one or more grids, one or more grids include a plurality of grid structures disposed on a waveguide substrate, the grid structures include waveguide material, and the plurality of grid structures include external grid structures on the outer edges of one or more grids. Waveguide layers are disposed on a waveguide substrate between the external grid structures and the edges of the waveguide substrate, the waveguide layers include waveguide material, and coatings are disposed on the waveguide layers, and the coatings have tapered portions tapered from at least one of the external grid structures to a planar portion of the coating.

Description

Technical Field

[0001]

[0001] Embodiments of the present disclosure generally relate to waveguide combiners. More specifically, the embodiments described herein provide a waveguide combiner having a waveguide layer and a coating having a tapered portion disposed thereon.

Background Art

[0002] Description of Related Art

[0002] Virtual reality is generally considered to be a computer-generated simulated environment in which a user appears to have a physical presence. A virtual reality experience is generated three-dimensionally and can be viewed using a head-mounted display (HMD), such as glasses or other wearable display devices, having a near-eye display panel as a lens for displaying a virtual reality environment that replaces the actual environment.

[0003]

[0003] However, augmented reality enables an experience in which a user can view the surrounding environment through the display lens of glasses or other HMD device, but can also view an image of a virtual object that is generated for display and appears as part of the environment. Augmented reality can include not only virtual images, graphics, and videos that enhance or augment the environment experienced by the user, but also any type of input, such as audio and tactile input. The image sharpness of the virtual image can be affected by the environment.

[0004]

[0004] Therefore, there is a need for a waveguide combiner having a waveguide layer and a coating having a tapered portion disposed thereon.

Summary of the Invention

[0005]

[0005] The embodiments described herein generally relate to systems and methods used in waveguide combiners. More specifically, the embodiments described herein provide a waveguide combiner having a waveguide layer and a coating having a tapered portion disposed thereon.

[0006]

[0006] In one embodiment, a waveguide is provided. The waveguide includes one or more gratings, one or more gratings including a plurality of grating structures disposed on a waveguide substrate, the grating structures including waveguide material, and the plurality of grating structures including an outer grating structure on the outer edge of one or more gratings. A waveguide layer is disposed on the waveguide substrate between the outer grating structure and the edge of the waveguide substrate, the waveguide layer including waveguide material, and a coating is disposed on the waveguide layer, the coating having tapered portions tapered from at least one of the outer grating structures to the planar portion of the coating.

[0007]

[0007] In another embodiment, a waveguide is provided. The waveguide is one or more grids comprising a plurality of grid structures disposed on a waveguide substrate, wherein the plurality of grid structures comprises one or more grids comprising an outer grid structure at the outer edge of one or more grids, a waveguide layer disposed on the waveguide substrate between the outer grid structure and the edge of the waveguide substrate, and a coating disposed on the waveguide layer, the coating having a tapered portion that is tapered from at least one of the outer grid structures to a planar portion of the coating adjacent to the outer tapered edge of the tapered portion.

[0008]

[0008] In yet another embodiment, a waveguide is provided. The waveguide includes one or more grids, which include a plurality of grid structures disposed on a waveguide substrate. The plurality of grid structures include a waveguide material and an outer grid structure at the outer edge of one or more grids. The waveguide also includes a waveguide layer disposed on the waveguide substrate between the outer grid structure and the edge of the waveguide substrate, and a coating disposed on the waveguide layer, the coating having a tapered portion that is tapered from at least one of the outer grid structures to a planar portion of the coating. The waveguide layer includes a waveguide material having the same thickness as the plurality of grid structures.

[0009]

[0009] To enable a detailed understanding of the above-described features of the Disclosure, a more specific description of the Disclosure, which has been briefly summarized above, can be obtained by referring to embodiments. Some of these embodiments are illustrated in the accompanying drawings. However, it should be noted that the accompanying drawings only illustrate exemplary embodiments of the Disclosure and should not be considered to limit the scope of the Disclosure, as other equally valid embodiments of the Disclosure are also permissible. [Brief explanation of the drawing]

[0010] [Figure 1A] A schematic top view of a waveguide combiner according to a certain embodiment is shown. [Figure 1B] A schematic cross-sectional view of a portion of the waveguide combiner shown in Figure 1A, according to a certain embodiment, is provided. [Modes for carrying out the invention]

[0011]

[0012] To facilitate understanding, the same reference numerals were used where possible to indicate identical elements common to multiple figures. It is assumed that elements and features of one embodiment may be usefully incorporated into other embodiments without further description.

[0012]

[0013] Embodiments of this specification generally relate to waveguide combiners for augmented reality. More specifically, this disclosure relates to a system and method for a waveguide combiner having a waveguide layer and a coating having a tapered portion disposed thereon.

[0013]

[0014] Diffraction waveguide combiners use a grating on a transparent substrate to reconstruct and redirect a virtual image from a light source to the user's eye, allowing the user to see the surrounding environment. However, waveguide combiners use high refractive index substrates or coatings that reflect some of the incident light, resulting in low transmittance and undesirable reflections. This disclosure provides a waveguide combiner having a coating with a taper at the boundary between the grating region and the waveguide region. The tapered coating reduces phase breaks at the boundary, minimizes reflections from ambient light, and improves the modulation transfer function (MTF).

[0014]

[0015] Figure 1A is a schematic top view of a waveguide combiner 100. The waveguide combiner 100 includes one or more grids 112. One or more grids 112 may include an input coupling grid 102, a pupil expansion grid 104, and an output coupling grid 106. A coating 108 is placed on a waveguide substrate (not shown) between one or more grids 112. One or more grids 112 include a grid structure 114 of waveguide material. The waveguide material has a grid refractive index of about 2.0 to about 3.0. In some embodiments, the grid refractive index is about 2.2 to about 2.7. The waveguide material includes, but is not limited to, titanium oxide, niobium oxide, silicon nitride, silicon dioxide, or a combination thereof. The coating 108 has a coating refractive index lower than the grid refractive index, such as between about 1.4 and about 1.8. The coating may be an anti-reflective coating. The anti-reflective coating includes, but is not limited to, silicon oxide, silicon nitride, or a combination thereof.

[0015]

[0016] Furthermore, each of the input coupling grid 102, the pupil expanding grid 104, and the output coupling grid 106 may include one or more grids 112 disposed within them. The waveguide combiner 100 further includes at least one tapered portion 110 of the coating 108 over the input coupling grid 102, the pupil expanding grid 104, the output coupling grid 106, or a combination thereof, as shown in Figure 1A. Each of the at least one tapered portion 110 of the coating 108 begins from at least one of the external grid structures into the planar portion of the coating 102. The coating 108 has tapered portions 110 that taper from at least one of the external structures to the planar portion of the coating 102. The tapered portions 110 do not have to completely surround one or more grids 112, and may be located only on specific sides or portions of one or more grids 112. For example, when the waveguide region of a waveguide combiner is coated with an anti-reflective coating such as coating 102, the virtual image sharpness of the waveguide combiner is impaired. When a pupil corresponding to a desired wavelength and field of view propagates using total internal reflection (TIR) ​​at a sharp (e.g., non-tapered) coating boundary between the waveguide and the lattice region (such as the edge of coating 102 adjacent to one of the external lattice structures 114A), the amplitude and phase of the two parts of the pupil interacting with two different regions become discontinuous, which can reduce image sharpness. By including a taper, such as a tapered portion 110, on coating 102, the amplitude and phase of light propagation across the pupil are improved, enhancing the modulation transfer function and virtual image sharpness of the waveguide combiner. This improves transmittance through the waveguide and reduces undesirable reflections. Furthermore, the tapered portion 110 includes an angle and thickness that reduces wavefront aberration in the pupil as it is guided from the optical engine to the user's eye.

[0016]

[0017] The input coupling grating 102 receives an intensified incident light beam (virtual image) from a microdisplay (not shown). The incident light beam undergoes total internal reflection (TIR) ​​and propagates within the waveguide combiner 100, directing the virtual image to the pupil-expanding grating 104. The incident light beam continues under TIR and propagates within the waveguide combiner 100, directing the virtual image to the output coupling grating 106, where the incident light beam is outcoupled to the user. As the incident light beam propagates within the TIR of the waveguide combiner 100, a portion of the light beam is incident on the input coupling grating 102, the pupil-expanding grating 104, and the output coupling grating 106, while a portion of the light beam is incident on an adjacent region of the waveguide substrate.

[0017]

[0018] Figure 1B shows a schematic cross-sectional side view of a portion of the waveguide combiner 100 shown in Figure 1A. More specifically, Figure 1B shows a cross-section of the output coupling grid 106, although the components described herein may also be components of the input coupling grid 102 or the Pupil expansion grid 104.

[0018]

[0019] As shown in Figure 1B, the waveguide combiner 100 includes a waveguide substrate 116 which includes a grid region 120A and a waveguide region 120B. The grid region 120A includes one or more grids 112 on which a plurality of grid structures 114 are arranged. Each of the one or more grids 112 includes an external grid structure 114A located at the edge of the grid 112.

[0019]

[0020] Waveguide region 120A includes a waveguide layer 118 having waveguide material and positioned on top of 116. The waveguide layer 118 is positioned between the external lattice structure 114A and the edge 116A of the waveguide substrate 116. The thickness of the waveguide layer 118 is the same as that of the multiple lattice structures 114. The coating 108 has a thickness between approximately 10 nanometers (nm) and approximately 800 nm. The coating 108 is positioned on top of the waveguide layer 118 and has a tapered portion 110 from an outer tapered edge 126 to an inner tapered edge 124. As described above, the coating 108 is positioned adjacent to one or more lattices 112 and the edge 116A of the waveguide substrate 116. The inner tapered edge 124 is positioned adjacent to one of the external lattice structures 114A. The outer tapered edge 126 is at the boundary between the planar portions 122 of the coating 108. The planar portion 122 of the coating 108 is part of the coating 108 having a substantially uniform thickness. The distance of the tapered portion 110, for example, the distance between the outer tapered edge 126 and the inner tapered edge 124, is from about 1 micrometer (μm) to about 2000 μm. In some embodiments, the distance of the tapered portion 110 is from about 10 μm to about 1500 μm.

[0020]

[0021] This disclosure provides a tapered coating architecture on a waveguide combiner for head-mounted augmented reality applications. The coating is an anti-reflective coating that prevents light reflection at orthogonal angles within the waveguide substrate and promotes light propagation against total internal reflection. The coating not only reduces undesirable reflections on the lattice side but also enhances the sharpness of the virtual image, significantly improving the user experience and reducing distractions.

[0021]

[0022] The above description applies to embodiments of the present disclosure, but other embodiments and further embodiments of the present disclosure may be devised without departing from the basic scope of the present disclosure, and the scope of the present disclosure is determined by the following claims.

Claims

1. Waveguide, One or more grids, comprising multiple grid structures arranged on a waveguide substrate, The lattice structure includes a waveguide material, The plurality of grid structures include an outer grid structure at the outer edge of one or more of the grids. One or more grids, A waveguide layer disposed on the waveguide substrate between the external grid structure and the edge of the waveguide substrate, comprising the waveguide layer containing the waveguide material, A coating disposed on the waveguide layer, the coating having a tapered portion that tapers from at least one of the external grid structures to the planar portion of the coating, Waveguides, including

2. The waveguide according to claim 1, wherein the coating is disposed on the waveguide substrate between the external grid structure and the edge of the waveguide substrate.

3. The waveguide according to claim 1, wherein one or more of the grids are one of an input coupling region, an intermediate region, or an output coupling region.

4. The waveguide according to claim 1, wherein the waveguide layer and the grid structure have the same thickness.

5. The waveguide according to claim 1, wherein the coating has a refractive index of less than 2.

0.

6. The waveguide according to claim 1, wherein the coating includes a coating refractive index, the waveguide layer includes a waveguide layer refractive index, and the coating refractive index is smaller than the waveguide layer refractive index.

7. The waveguide according to claim 1, wherein the coating includes a planar portion adjacent to the outer tapered edge of the tapered portion.

8. Waveguide, One or more grids comprising a plurality of grid structures arranged on a waveguide substrate, wherein the plurality of grid structures include waveguides, and the outer edge of the one or more grids includes an outer grid structure, A waveguide layer having waveguide material, disposed on the waveguide substrate between the outer grid structure and the edge of the waveguide substrate, A coating disposed on the waveguide layer, having a coating refractive index smaller than the refractive index of the waveguide layer, and having a tapered portion that is tapered from at least one of the external lattice structures to a planar portion of the coating adjacent to the outer tapered edge of the tapered portion, Waveguides, including

9. The waveguide according to claim 8, wherein one or more of the grids are one of an input coupling region, an intermediate region, or an output coupling region.

10. The waveguide according to claim 8, wherein the coating has a thickness between approximately 10 nanometers and approximately 800 nanometers.

11. The waveguide according to claim 8, wherein the refractive index of the coating is less than 2.

0.

12. The waveguide according to claim 8, wherein the waveguide layer and the grid structure have the same thickness.

13. The waveguide according to claim 8, wherein the distance between the inner tapered edge and the outer tapered edge of the coating is approximately 1 micrometer to approximately 2000 micrometers.

14. Waveguide, One or more grids comprising a plurality of grid structures arranged on a waveguide substrate, wherein the plurality of grid structures comprises a waveguide material and an outer grid structure at the outer edge of the one or more grids, A waveguide layer disposed on the waveguide substrate between the outer grid structure and the edge of the waveguide substrate, comprising the waveguide material and having the same thickness as the plurality of grid structures, A coating disposed on the waveguide layer, the coating having a tapered portion that tapers from at least one of the external grid structures to the planar portion of the coating, Waveguides, including

15. The waveguide according to claim 14, wherein the one or more grids are one of an input coupling region, an intermediate region, or an output coupling region.

16. The waveguide according to claim 14, wherein the coating includes a coating refractive index, the waveguide layer includes a waveguide layer refractive index, and the coating refractive index is smaller than the waveguide layer refractive index.

17. The waveguide according to claim 16, wherein the refractive index of the coating is less than 2.

0.

18. The waveguide according to claim 14, wherein the coating has a thickness between approximately 10 nanometers and approximately 800 nanometers.

19. The waveguide according to claim 14, wherein the tapered portion includes an outer tapered edge adjacent to the planar portion of the coating and an inner tapered edge adjacent to the external grid structure.

20. The waveguide according to claim 20, wherein the distance between the inner tapered edge and the outer tapered edge of the coating is approximately 1 micrometer to approximately 2000 micrometers.

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