Magic Leap Patent | Methods, devices, and systems for illuminating spatial light modulators

Patent: Methods, devices, and systems for illuminating spatial light modulators

Publication Number: 20250155720

Publication Date: 2025-05-15

Assignee: Magic Leap

Abstract

An optical device may include a wedge-shaped light turning element, a first surface that is parallel to a horizontal axis, a second surface opposite to the first surface that is inclined with respect to the horizontal axis by a wedge angle, and a light module including light emitters. The light module can be configured to combine light emitted by the emitters. The optical device can further include a light input surface that is between the first and the second surfaces and disposed with respect to the light module to receive light emitted from the emitters. The optical device may include an end reflector disposed on a side opposite the light input surface. Light coupled into the light turning element may be reflected by the end reflector and/or reflected from the second surface towards the first surface.

Claims

What is claimed is:

1. An optical device comprising:a wedge-shaped light turning element comprising:a first surface parallel to a horizontal axis;a second surface that is opposite the first surface and inclined with respect to the horizontal axis by a wedge angle;a light input surface between the first and the second surfaces, the light input surface configured to receive light emitted from a light source, wherein the light includes light having a first polarization state and light having a second polarization state;an end reflector disposed on a side of the light turning element that is opposite the light input surface; anda plurality of light turning features disposed on the second surface, the plurality of light turning features including a polarization selective element to redirect, toward the first surface, light having the first polarization state and to not redirect light having the second polarization state,wherein the second surface is inclined such that a height of the light input surface is less than a height of the side on which the end reflector is disposed, andwherein at least a portion of the light received into the light turning element is reflected by the end reflector and redirected by the plurality of turning features towards the first surface.

2. The optical device of claim 1, wherein the first polarization state is an s-polarization state, and wherein the second polarization state is a p-polarization state.

3. The optical device of claim 1, wherein the polarization selective element comprises at least one of a thin film, a dielectric coating, or a wire grid.

4. The optical device of claim 1, wherein the end reflector is configured to reflect at least a portion of the light received through the light input surface back toward the light input surface along a direction that is substantially parallel to the horizontal axis.

5. The optical device of claim 1, wherein the end reflector comprises a spherical mirror or a parabolic mirror.

6. The optical device of claim 1, wherein the end reflector comprises a reflective holographic structure comprising one or more holograms.

7. The optical device of claim 1, further comprising a spatial light modulator disposed with respect to the first surface such that at least a portion of the light received into the light turning element through the input surface is reflected by the end reflector and redirected by the plurality of turning features towards the first surface and toward the spatial light modulator.

8. The optical device of claim 7, wherein the plurality of light turning features are configured to redirect, toward the spatial light modulator, a portion of the light that is received through the light input surface and that has the first polarization state.

9. The optical device of claim 7, wherein the plurality of turning features are configured to transmit at least a portion of the light that is reflected from the spatial light modulator and that has the second polarization state.

10. The optical device of claim 7, wherein the spatial light modulator is configured to modulate received light and direct the modulated light back toward the first surface.

11. The optical device of claim 10, wherein the spatial light modulator is configured to emit modulated light having the second polarization state.

12. The optical device of claim 11, wherein the optical device further comprises a clean-up polarizer that is configured to transmit light having the second polarization state and block light having the first polarization state.

13. The optical device of any of claim 1, further comprising a refractive optical element disposed over the light turning element.

14. The optical device of claim 13, further comprising a polarization selective component disposed over the refractive optical element.

15. The optical device of claim 1, wherein the wedge angle is between about 15 degrees and about 45 degrees.

16. The optical device of claim 1, further comprising the light source, wherein the light source is disposed with respect to the light input surface such that at least a portion of the light from the light source that is received into the light turning element through the input surface is reflected by the end reflector and redirected by the plurality of turning features towards the first surface in an angular range between about ±10 degrees with respect to a normal to the first surface.

17. The optical device of claim 1, wherein the end reflector is configured to collimate the light that is incident on the end reflector.

Description

PRIORITY CLAIM

This application is a continuation of U.S. patent application Ser. No. 18/470,801, filed on Sep. 20, 2023, which is a continuation of U.S. patent application Ser. No. 17/456,083, filed on Nov. 22, 2021, which is a continuation of U.S. patent application Ser. No. 15/927,970, filed on Mar. 21, 2018, which claims the benefit of priority under 35 U.S.C. § 119(e) to U.S. Provisional Patent Application No. 62/474,591, filed on Mar. 21, 2017. The entire contents of each of the applications recited in this paragraph are hereby incorporated by reference into this application.

BACKGROUND

Field

The present disclosure relates to optical devices, including augmented reality imaging and visualization systems.

Description of the Related Art

Modern computing and display technologies have facilitated the development of systems for so called “virtual reality” or “augmented reality” experiences, in which digitally reproduced images or portions thereof are presented to a user in a manner wherein they seem to be, or may be perceived as, real. A virtual reality, or “VR”, scenario typically involves the presentation of digital or virtual image information without transparency to other actual real-world visual input; an augmented reality, or “AR”, scenario typically involves presentation of digital or virtual image information as an augmentation to visualization of the actual world around the user. A mixed reality, or “MR”, scenario is a type of AR scenario and typically involves virtual objects that are integrated into, and responsive to, the natural world. For example, an MR scenario may include AR image content that appears to be blocked by or is otherwise perceived to interact with objects in the real world.

Referring to FIG. 1, an augmented reality scene 10 is depicted. The user of an AR technology sees a real-world park-like setting 20 featuring people, trees, buildings in the background, and a concrete platform 30. The user also perceives that he/she “sees” “virtual content” such as a robot statue 40 standing upon the real-world platform 30, and a flying cartoon-like avatar character 50 which seems to be a personification of a bumble bee. These elements 50, 40 are “virtual” in that they do not exist in the real world. Because the human visual perception system is complex, it is challenging to produce AR technology that facilitates a comfortable, natural-feeling, rich presentation of virtual image elements amongst other virtual or real-world imagery elements.

Systems and methods disclosed herein address various challenges related to AR and VR technology.

Polarizing beam splitters may be used in display systems to direct polarized light to light modulators and then to direct this light to a viewer. There is a continuing demand to reduce the sizes of display systems generally and, as a result, there is also a demand to reduce the sizes of the constituent parts of the display systems, including constituent parts utilizing polarizing beam splitters.

SUMMARY

Various implementations described herein include an illuminating system configured to provide illumination (e.g., a front light or a back light) to one or more spatial light modulators (e.g., liquid crystal on silicon (LCOS) devices). The illumination systems contemplated herein are configured to direct light having a first polarization state towards a spatial light modulator and direct light reflected from the spatial light modulator having a second polarization state different from the first polarization towards a viewer. The illumination systems contemplated herein can be configured as polarization beam splitting components having a reduced size.

A head mounted display system can be configured to project light to an eye of a user to display augmented reality image content in a vision field of the user. The head-mounted display system may include a frame that is configured to be supported on a head of the user. The head-mounted display system may also include an eyepiece disposed on the frame. At least a portion of the eyepiece may be transparent and/or disposed at a location in front of the user's eye when the user wears the head-mounted display such that the transparent portion transmits light from the environment in front of the user to the user's eye to provide a view of the environment in front of the user. The eyepiece can include one or more waveguides disposed to direct light into the user's eye.

The head mounted display system may further include a light source that is configured to emit light and/or a wedge-shaped light turning element. The wedge-shaped light turning element may include a first surface that is parallel to an axis. The wedge-shaped light turning element can further include a second surface disposed opposite to the first surface and/or inclined with respect to the axis by a wedge angle. A light input surface between the first and the second surfaces can be configured to receive light emitted from a light source. The wedge-shaped light turning element can include an end reflector that is disposed on a side opposite the light input surface. The second surface of the wedge-shaped light turning element may be inclined such that a height of the light input surface is less than a height of the end reflector opposite the light input surface and/or such that light coupled into the wedge-shaped light turning element is reflected by the end reflector and redirected by the second surface towards the first surface.

The head mounted display system may further include a spatial light modulator that is disposed with respect to the wedge-shaped light turning element to receive the light ejected from the wedge-shaped light turning element and modulate the light. The wedge-shaped light turning element and the spatial light modulator may be disposed with respect to the eyepiece to direct modulated light into the one or more waveguides of the eyepiece such that the modulated light is directed into the user's eye to form images therein.

An optical device comprising may include a wedge-shaped light turning element. The optical device can include a first surface that is parallel to a horizontal axis and a second surface opposite to the first surface that is inclined with respect to the horizontal axis by a wedge angle α. The optical device may include a light module that includes a plurality of light emitters. The light module can be configured to combine light for the plurality of emitters. The optical device can further include a light input surface that is between the first and the second surfaces and is disposed with respect to the light module to receive light emitted from the plurality of emitters. The optical device may include an end reflector that is disposed on a side opposite the light input surface. The second surface may be inclined such that a height of the light input surface is less than a height of the side opposite the light input surface. The light coupled into the wedge-shaped light turning element may be reflected by the end reflector and/or reflected from the second surface towards the first surface.

An illumination system can include a light source that is configured to emit light, and a polarization sensitive light turning element. The polarization sensitive light turning element can include a first surface disposed parallel to an axis and a second surface opposite to the first surface. The polarization sensitive light turning element may include a light input surface that is between the first and the second surfaces and is configured to receive light emitted from the light source. The polarization sensitive light turning element can further include an end reflector that is disposed on a side opposite the light input surface. The second surface of the polarization sensitive light turning element may be such that light coupled into the polarization sensitive light turning element is reflected by the end reflector and/or redirected by the second surface towards the first surface. The illumination system can further include a spatial light modulator that is disposed with respect to the polarization sensitive light turning element to receive the light ejected from the polarization sensitive light turning element and modulate the light.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a user's view of augmented reality (AR) through an AR device, according to some embodiments.

FIG. 2 illustrates an example of wearable display system, according to some embodiments.

FIG. 3 illustrates a display system for simulating three-dimensional imagery for a user, according to some embodiments.

FIG. 4 illustrates aspects of an approach for simulating three-dimensional imagery using multiple depth planes, according to some embodiments.

FIGS. 5A-5C illustrate relationships between radius of curvature and focal radius, according to some embodiments.

FIG. 6 illustrates an example of a waveguide stack for outputting image information to a user, according to some embodiments.

FIG. 7 illustrates an example of exit beams outputted by a waveguide, according to some embodiments.

FIG. 8 illustrates an example of a stacked waveguide assembly in which each depth plane includes images formed using multiple different component colors, according to some embodiments.

FIG. 9A illustrates a cross-sectional side view of an example of a set of stacked waveguides that each includes an incoupling optical element, according to some embodiments.

FIG. 9B illustrates a perspective view of an example of the set of stacked waveguides of FIG. 9A, according to some embodiments.

FIG. 9C illustrates a top-down plan view of an example of the set of stacked waveguides of FIGS. 9A and 9B, according to some embodiments.

FIG. 10 schematically illustrates an example wedge illumination system, according to some embodiments.

FIG. 11 illustrates a ray trace with relation to the illumination system illustrated in FIG. 10, according to some embodiments.

FIG. 12A illustrates a perspective view of the illumination system illustrated in FIG. 10, according to some embodiments.

FIG. 12B illustrates an exploded perspective view of the illumination system illustrated in FIG. 12A, according to some embodiments.

FIG. 13A illustrates a method of manufacturing a polarization sensitive reflector, according to some embodiments.

FIG. 13B illustrates a polarization sensitive reflector, according to some embodiments.

FIG. 13C illustrates a method of manufacturing a polarization sensitive reflector manufactured as shown in FIG. 13A, according to some embodiments.

FIG. 13D illustrates a polarization sensitive reflector manufactured using the method illustrated in FIGS. 13A-13C, according to some embodiments.

FIG. 14A illustrates polarization coatings with cholesteric liquid crystal gratings, according to some embodiments.

FIG. 14B illustrates polarization coatings with cholesteric liquid crystal gratings, according to some embodiments.

FIG. 15 illustrates coating locations of a polarizing beam splitter, according to some embodiments.

FIG. 16 illustrates features of a polarizing beam splitter, according to some embodiments.

FIGS. 17A-17H illustrate various example configurations of an illumination module in relation to a polarizing beam splitter according to some embodiments.

FIGS. 18A-18M illustrate various example configurations of illumination modules, according to some embodiments.

FIGS. 18N-18P illustrate various example configurations of illumination modules combined with polarization beam splitters, according to some embodiments.

FIGS. 18Q-18V illustrate various example configurations of illumination modules, according to some embodiments.

FIG. 19 illustrates an illumination system that may include a delivery system between the illumination module and the PBS, according to some embodiments.

FIG. 20A shows an example light pipe integrator including color source areas, according to some embodiments.

FIG. 20B shows an example light pipe integrator including color source areas, according to some embodiments.

FIGS. 20C-20D show examples of an alternative illumination module.

FIG. 21A shows a basic structure of an integrated dichroic combiner and light integrator, according to some embodiments.

FIG. 21B shows an example of an embodiment of FIG. 21A with light emitters and combining elements, according to some embodiments.

FIG. 21C shows an example embodiment of FIG. 21A with only one combining element as well as a light integrator, according to some embodiments.

FIG. 22A shows a side view of an example reflective illumination module, according to some embodiments.

FIG. 22B shows an isometric view of the example reflective illumination module of FIG. 22A, according to some embodiments.

FIG. 22C shows an example reflective illumination module including an extension, according to some embodiments.

FIG. 23A shows an example of a broadband light source, according to some embodiments.

FIG. 23B shows a first color cell off-state, according to some embodiments.

FIG. 23C shows a second color cell off-state, according to some embodiments.

FIG. 23D shows a third color cell off-state, according to some embodiments.

FIG. 23E shows an on-state where transmission of each color of light is effected, according to some embodiments.

FIG. 24 illustrates a perspective view of an illumination system, according to some embodiments.

FIG. 25 illustrates a perspective view of another example illumination system, according to some embodiments.

FIG. 26 schematically illustrates an illumination system configured to provide illumination to a spatial light modulator, according to some embodiments.

FIG. 27 schematically illustrates an illumination system configured to provide illumination to a spatial light modulator associated with various embodiments of display systems contemplated herein, according to some embodiments. The inset in FIG. 27 provides an enlarged view of a section of the illumination system showing turning features including microstructure reflecting collimated light, according to some embodiments.

FIG. 28A illustrates an example implementation of turning features that are included in the illumination system illustrated in FIG. 27, according to some embodiments.

FIG. 28B illustrates an example implementation of turning features that are included in the illumination system illustrated in FIG. 27, according to some embodiments.

FIG. 28C illustrates an example implementation of turning features that are included in the illumination system illustrated in FIG. 27, according to some embodiments.

FIG. 28D illustrates an example implementation of turning features that are included in the illumination system illustrated in FIG. 27, according to some embodiments.

FIG. 29A illustrates an example implementation of the illumination system including turning features with optical power, according to some embodiments.

FIG. 29B illustrates an example implementation of the illumination system including turning features with optical power, according to some embodiments.

FIG. 30 illustrates an embodiment of the illumination system including a reflective holographic component, according to some embodiments.

FIG. 31 schematically illustrates a method of manufacturing an embodiment of a compact polarization beam splitter contemplated herein, according to some embodiments.

FIG. 32 illustrates an example of a display device incorporating a light recycling system to recycle light, according to some embodiments.

FIG. 33 illustrates an example of a display device incorporating a light recycling system to recycle light, according to some embodiments.

FIG. 34 illustrates an example of a display device incorporating a light recycling system to recycle light, according to some embodiments.

FIG. 35 illustrates an example of a display device incorporating a light recycling system to recycle light, according to some embodiments.

FIG. 36 illustrates an example of a display device incorporating a light recycling system to recycle light, according to some embodiments.

FIG. 37 illustrates an illumination device with an incoupling element that deflects light so as to couple into the light redirecting element, according to some embodiments.

FIG. 38 illustrates an illumination module and a polarization beam splitter used in combination with an eyepiece to provide images thereto, according to some embodiments.

The drawings are provided to illustrate example embodiments and are not intended to limit the scope of the disclosure. Like reference numerals refer to like parts throughout.