Waveguide combiner with reduced light leakage

Patent metadata

Field	Value
Publication number	US-12585118-B2
Application number	US-202318326484-A
Country	US
Kind code	B2
Filing date	May 31, 2023
Priority date	May 31, 2023
Publication date	Mar 24, 2026
Grant date	Mar 24, 2026

Abstract

Optical filters are disclosed for reducing leakage of light used for virtual images from a mixed-reality head-mounted display (HMD) device having a waveguide combiner. The optical filters include spectral-sensitive wideband and narrowband reflectors comprising triple-notch filters or single-notch filters that reflect forward-propagating virtual image light back to a user's eyes. The optical filters further include light deflectors having planar and curved configurations comprising volume Bragg gratings (VBGs), liquid crystal Bragg gratings, and partially-reflective mirror arrays. A light deflector steers forward-propagating virtual image light to impart an angular change in propagation direction. The steered light is absorbed and/or diffused by structures in the HMD device and/or deflected to prevent the outward appearance of virtual image overlay with the HMD device user's eyes.

First claim

What is claimed:

1 . A device comprising:
a waveguide combiner usable in a mixed-reality environment in which virtual images are displayed by the waveguide combiner over a user's views of a real world, including
a see-through waveguide through which the user views the real world, the waveguide having a frontside surface facing an eye of the user and a backside surface facing the real world;
an input coupler disposed on the waveguide configured to in-couple the virtual images which are generated by a display engine into the waveguide;
an output coupler disposed on the waveguide configured to out-couple the virtual images from the waveguide to the eye of the user; and
a spectral-sensitive reflector disposed on the backside surface of the waveguide and located along a forward-propagating light path extending from the output coupler of the waveguide combiner towards the real world, wherein the spectral-sensitive reflector reflects forward-propagating light out-coupled from the output coupler back towards the eye of the user; and
a light deflector that steers forward-propagating virtual image light that is leaking from the waveguide combiner by imparting an angular change in a propagation direction of the virtual image light to change the propagation direction to be away from the eye of the user towards a visor.

2 . The device of claim 1 in which the display engine outputs monochromatic virtual image light, and the spectral-sensitive reflector comprises a single-notch filter having a bandpass matching an output of the display engine.

3 . The device of claim 1 in which the display engine outputs virtual image light according to an RGB (red, green, blue) color model, and the spectral-sensitive reflector comprises a triple-notch filter having a bandpass matching the output of the display engine.

4 . The device of claim 1 in which the spectral-sensitive reflector comprises a thin film reflective coating that is disposed on a substrate as alternating layers of dielectric materials each having a different index of refraction.

5 . The device of claim 4 in which the dielectric materials comprise one of silicon dioxide (SiO 2 ), titanium dioxide (TiO 2 ), or aluminum oxide (Al 2 O 3 ).

6 . The device of claim 4 in which the substrate and the waveguide are coupled with an adhesive applied around a periphery of the substrate to maintain a uniform parallel gap between a plane of the substrate and a plane of the waveguide within a predetermined threshold.

7 . The device of claim 1 in which the display engine generates polychromatic virtual images based on a color model, the waveguide combiner comprises a single plate that propagates all colors of the color model,
wherein the light deflector is disposed along the forward-propagating light path,
wherein the light deflector is located on a transparent eye shield, and
further wherein the visor is a laterally extending visor above the eye shield in an as-worn orientation, wherein the angular change in the propagation direction of the virtual image light causes the forward-propagating virtual image light to be steered into the visor.

8 . A head-mounted display (HMD) device wearable by a user and supporting a mixed-reality experience comprising a display of virtual images for objects in a virtual world and real-world images for objects in a real world, comprising:
a visor; a display engine generating virtual image light for the virtual images; a waveguide combiner comprising a see-through waveguide having an eye-facing side and a real-world-facing side, an input coupler disposed on the waveguide configured for in-coupling the virtual image light from the display engine into the waveguide, and an output coupler disposed on the waveguide for out-coupling the virtual images from the waveguide to an eye of the user, wherein the waveguide combiner includes a see-through portion, located on the HMD device in front of the eye of the user when the HMD device is donned, through which the user views the real world; and a light deflector disposed along a forward-propagating light path extending from the output coupler of the waveguide combiner towards the real world, wherein the light deflector steers forward-propagating virtual image light to impart an angular change in a propagation direction of the virtual image light to change the propagation direction to be away from the eye of the user towards the visor.

9 . The HMD device of claim 8 further comprising an intermediate coupler in which the input coupler receives virtual image light generated by the display engine having an entrance pupil and the waveguide combiner is configured as an exit pupil expander to provide an exit pupil for virtual images that is expanded in two directions relative to the entrance pupil, wherein the intermediate coupler performs exit pupil expansion in a first direction and the output coupler performs exit pupil expansion in a second direction.

10 . The HMD device of claim 8 in which the display engine generates polychromatic virtual images based on a color model and the waveguide combiner comprises a single plate that propagates all colors of the color model.

11 . The HMD device of claim 8 further comprising a second see-through waveguide and a third see-through waveguide, each of the see-through waveguides having corresponding input couplers and out-couplers and being configured in a stack wherein each see-through waveguide in the waveguide combiner propagates one or more optical beams for the virtual images for a different component of a polychromatic color model.

12 . The HMD device of claim 8 in which the light deflector comprises one of volume Bragg grating (VBG), liquid-crystal Bragg grating, or one or more arrays of partial mirrors embedded in an optical substrate.

13 . The HMD device of claim 8 further comprising a transparent eye shield and in which the light deflector is located on the eye shield.

14 . The HMD device of claim 13 wherein the visor is laterally extending and is disposed on the HMD device above the eye shield in an as-worn orientation, wherein the angular change in the propagation direction of the virtual image light causes the forward-propagating virtual image light to be steered into the visor.

15 . The HMD device of claim 14 in which the visor includes one of light absorber or light diffuser.

16 . The HMD device of claim 8 in which the light deflector is planar or curved.

17 . The HMD device of claim 8 in which the angular change in the propagation direction of forward-propagating virtual image light shifts the virtual images to prevent overlay of the virtual images with the user's eyes responsively to the forward-propagating virtual image light being seen by an observer of the HMD device user.

18 . A method for reducing light leakage in an optical display system configured to display virtual images in a mixed-reality usage scenario in which the virtual images are seen by a user as superimposed over a physical real-world environment, comprising:
providing a see-through waveguide combiner comprising at least one transparent waveguide having a first surface towards which a user of the waveguide combiner looks to view the real-world environment, and a second surface opposite the first surface, in which an input coupler and an output coupler are disposed on the waveguide; configuring the waveguide combiner with a spectral-sensitive reflector on the first surface of the waveguide, the spectral-sensitive reflector reflecting forward-propagating virtual image light that is leaking from the

Assignees

• Microsoft Technology Licensing Llc

Inventors

• Poon Yarn Chee
• Bolas Mark T
• Chatterjee Ishan
• Kress Bernard C
• Zhang Yifei

Classifications

• G02B2027/0112

  comprising device for genereting colour display · CPC title

• G02B2027/0178

  Eyeglass type (eyeglass details G02C) · CPC title

• G02B27/0172 Primary

  characterised by optical features · CPC title