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EP-4737987-A2 - WAVEGUIDE DISPLAY WITH GAZE TRACKING

EP4737987A2EP 4737987 A2EP4737987 A2EP 4737987A2EP-4737987-A2

Abstract

A display may include a waveguide. An input coupler may couple image light into the waveguide and an output coupler may couple the image light out of the waveguide. A surface relief grating on the waveguide may couple infrared light into the waveguide and may couple the infrared light out of the waveguide. The surface relief grating may additionally or alternatively couple reflected infrared light into the waveguide and out of the waveguide and towards an infrared sensor. The surface relief grating may also form a cross-coupler for the image light. The infrared sensor may gather infrared sensor data based on the reflected infrared light. Control circuitry may perform gaze tracking operations based on the infrared sensor data. The input and output couplers may also be formed from surface relief gratings or may include other optical components.

Inventors

  • AIETA, Francesco
  • COCILOVO, BYRON R.
  • OH, SE BAEK
  • PFEIFFER, JONATHAN B.

Assignees

  • Apple Inc.

Dates

Publication Date
20260506
Application Date
20220204

Claims (15)

  1. A display system (10) comprising: a waveguide (26) configured to direct image light (22) having a visible wavelength; a light source (36) configured to generate infrared light (42); diffractive grating structures (32) on the waveguide (26) and configured to diffract the infrared light (42) onto an output angle (B) that is outside a total internal reflection (TIR) range of the waveguide; an output coupler (30) on the waveguide (26) and configured to couple the image light (22) out of the waveguide; and control circuitry (16) configured to perform gaze tracking operations based at least in part on the infrared light (42) diffracted by the diffractive grating structures.
  2. The display system of claim 1, wherein the diffractive grating structures comprise a surface relief grating.
  3. The display system of any preceding claim, wherein the output coupler comprises an additional surface relief grating.
  4. The display system of claims 1 or 2, wherein the output coupler comprises a volume hologram.
  5. The display system of claim 1, wherein the diffractive grating structures comprise a volume hologram.
  6. The display system of claim 5, wherein the output coupler comprises a surface relief grating.
  7. The display system of claim 5, wherein the output coupler comprises a volume hologram.
  8. The display system of any preceding claim, wherein the output coupler comprises a louvered mirror.
  9. The display system of any preceding claim, wherein the diffractive grating structures are configured to receive reflected infrared light (44) and is configured to couple the reflected infrared light into the waveguide.
  10. The display system of claim 10, wherein the diffractive grating structures are configured to couple the reflected infrared light out of the waveguide.
  11. The display system of any preceding claim, wherein the diffractive grating structures are configured to couple the infrared light into the waveguide.
  12. The display system of any preceding claim, further comprising an input coupler configured to couple the image light into the waveguide.
  13. The display system of any preceding claim, wherein the diffractive grating structures are configured to diffract the image light towards the output coupler.
  14. A method of operating a display system, comprising: propagating, using a waveguide (26), image light (22) having a visible wavelength within a total internal reflection (TIR) range of the waveguide; outputting, using a light source (36), infrared light (42); diffracting, using diffractive grating structures (42), the infrared light onto an output angle (B) that is outside the TIR range; coupling, using an output coupler (30), the image light out of the waveguide; and performing, using control circuitry (16), gaze tracking operations based at least in part on the infrared light (42) diffracted by the diffractive grating structures.
  15. The method of claim 14, further comprising: redirecting, using the diffractive grating structures, the image light towards the output coupler.

Description

This application claims priority to U.S. Provisional Patent Application No. 63/148,496, filed February 11, 2021, which is hereby incorporated by reference herein in its entirety. Background This relates generally to optical systems and, more particularly, to optical systems for displays. Electronic devices may include displays that present images to a user's eyes. For example, devices such as virtual reality and augmented reality headsets may include displays with optical elements that allow users to view the displays. It can be challenging to design devices such as these. If care is not taken, the components used in displaying content may be unsightly and bulky, can consume excessive power, and may not exhibit desired levels of optical performance. Summary An electronic device such as a head-mounted device may have one or more near-eye displays that produce images for a user. The head-mounted device may be a pair of virtual reality glasses or may be an augmented reality headset that allows a viewer to view both computer-generated images and real-world objects in the viewer's surrounding environment. The display may include a display module, an infrared emitter, an infrared sensor, and a waveguide. The display module may generate image light at visible wavelengths. The infrared emitter may emit infrared light. An input coupler may couple the image light into the waveguide. An output coupler may couple the image light out of the waveguide and towards an eye box. A surface relief grating on the waveguide may couple the infrared light into the waveguide. The surface relief grating may couple the infrared light out of the waveguide and towards an eye box after the infrared light coupled into the waveguide by the surface relief grating has reflected at least once off of a surface of the waveguide. The display may include a cross-coupler for the image light that is separate from the surface relief grating or the surface relief grating may also form a cross-coupler for the image light. The cross-coupler may redirect the image light towards the output coupler and may optionally expand the image light. The input coupler and output coupler may also be formed from surface relief gratings (e.g., in the same layer of grating medium as the surface relief grating for coupling the infrared light into and out of the waveguide). Alternatively, the input and output couplers may include prisms, partial reflectors, louvered mirrors, volume holograms, meta-gratings, thin film holograms, etc. The surface relief grating may receive reflected infrared light from the eye box. The reflected infrared light may be a version of the infrared light coupled out of the waveguide by the surface relief grating that has reflected off of a portion of the user's eye at the eye box. The surface relief grating may couple the reflected infrared light into the waveguide. The surface relief grating may couple the reflected infrared light out of the waveguide and towards an infrared sensor after the reflected infrared light has reflected at least once off of the surface of the waveguide. The infrared sensor may generate infrared sensor data based on the reflected infrared light coupled out of the waveguide by the surface relief grating. Control circuitry may perform gaze tracking operations based on the infrared sensor data. Brief Description of the Drawings FIG. 1 is a diagram of an illustrative display system having display and gaze tracking capabilities in accordance with some embodiments.FIG. 2 is a top view of an illustrative optical system having a display module that provides image light to a waveguide and having an infrared emitter and an infrared sensor for performing gaze tracking in accordance with some embodiments.FIG. 3 is a front view of an illustrative waveguide having a visible light input coupler, a visible light cross coupler, a visible light output coupler, and grating structures that perform infrared input coupling and infrared output coupling for gaze tracking in accordance with some embodiments.FIG. 4 is a cross sectional bottom view of an illustrative waveguide having surface relief gratings that form a visible light input coupler, a visible light cross coupler, a visible light output coupler, an infrared input coupler, and an infrared output coupler in accordance with some embodiments.FIG. 5 is a two-dimensional k-space diagram showing how an illustrative visible light cross-coupler may also perform infrared input coupling and infrared output coupling for gaze tracking in accordance with some embodiments.FIG. 6 is a cross sectional bottom view showing how multiple waveguides may be used to redirect image light and infrared light towards an eye box in accordance with some embodiments. Detailed Description An illustrative system having a device with one or more near-eye display systems is shown in FIG. 1. System 10 may be a head-mounted device having one or more displays such as near-eye displays 14 mounted within support structu