Time-multiplexed display of virtual content at various depths

Abstract

To provide techniques for operating an optical system.SOLUTION: World light may be linearly polarized along a first axis. When the optical system is operating in accordance with a first state, a polarization of the world light may be rotated by 90 degrees, the world light may be linearly polarized along a second axis perpendicular to the first axis, and zero net optical power may be applied to the world light. When the optical system is operating in accordance with a second state, virtual image light may be projected onto an eyepiece of the optical system, the world light and the virtual image light may be linearly polarized along the second axis, a polarization of the virtual image light may be rotated by 90 degrees, and non-zero net optical power may be applied to the virtual image light.SELECTED DRAWING: Figure 12A

Description

[Background technology]

[0001] (Cross-reference of related applications) This application claims the benefit of priority to U.S. Provisional Patent Application No. 62 / 791,441, filed on January 11, 2019, titled "TIME-MULTIPLEXED DISPLAY OF VIRTUAL CONTENT AT VARIOUS DEPTHS," the contents of which are incorporated herein by reference as a whole.

[0002] Modern computing and display technologies are driving the development of systems for so-called "virtual reality" or "augmented reality" experiences, in which digitally reproduced images or parts thereof are presented to the user in a manner that appears, or can be perceived, as real. Virtual reality, or "VR," scenarios typically involve the presentation of digital or virtual imagery without transparency to other real-world visual inputs. Augmented reality, or "AR," scenarios typically involve the presentation of digital or virtual imagery as an extension of the user's visualization of the real world around them.

[0003] Despite the advances made in these display technologies, there is a need in this field for improved methods, systems, and devices related to augmented reality systems, particularly display systems. [Overview of the project] [Means for solving the problem]

[0004] This disclosure relates, in general, to techniques for improving the performance and user experience of optical systems. More specifically, embodiments of this disclosure provide systems and methods for operating augmented reality (AR) devices comprising adaptive lens assemblies and / or shutter elements for displaying virtual content at various depths. While this disclosure is described with reference to AR devices, it is applicable to various applications in computer vision and image display systems. A description of this disclosure is provided below with reference to a series of embodiments.

[0005] Example 1 is a method for operating an optical system, comprising the steps of: receiving light associated with a world object in the optical system; when the optical system is operating according to a first state, linearly polarizing the light associated with the world object along a first axis using the world-side polarizer of the optical system; rotating the polarization of the light associated with the world object by 90 degrees using the world-side switchable waveplate of the optical system; linearly polarizing the light associated with the world object along a second axis perpendicular to the first axis using the user-side polarizer of the optical system; applying a zero net refractive power to the light associated with the world object using the lens assembly of the optical system; when the optical system is operating according to a second state, projecting light associated with a virtual image onto the eyepiece of the optical system using the projector of the optical system; externally coupling the light associated with the virtual image toward the user-side polarizer using the eyepiece; and using the user-side polarizer The method includes the steps of linearly polarizing light associated with a world object and light associated with a virtual image along a second axis, rotating the polarization of the light associated with the virtual image by 90 degrees using a user-side switchable waveplate, and applying a non-zero net refractive force to the light associated with the virtual image using a lens assembly, wherein the optical system operates according to a first state when the world-side switchable waveplate is electrically activated and the user-side switchable waveplate is not electrically activated, and the optical system operates according to a second state when the user-side switchable waveplate is electrically activated and the world-side switchable waveplate is not electrically activated, and the world-side polarizer is coupled to the world-side switchable waveplate, the world-side switchable waveplate is coupled to the eyepiece on the world side of the eyepiece, the user-side polarizer is coupled to the eyepiece on the user side of the eyepiece, the lens assembly is coupled to the user-side polarizer, and the user-side switchable waveplate is positioned between the two layers of the lens assembly.

[0006] Embodiment 2 is an optical system comprising: a world-side polarizer configured to linearly polarize light associated with a world object along a first axis; a world-side switchable waveplate coupled to the world-side polarizer and configured to rotate the polarization of light associated with the world object by 90 degrees when the optical system is operating according to a first state; an eyepiece coupled to the world-side switchable waveplate; a projector configured to project light associated with a virtual image onto the eyepiece when the optical system is operating according to a second state; and an optical system coupled to the eyepiece and configured to linearly polarize light associated with a world object along a second axis perpendicular to the first axis when the optical system is operating according to a first state. The optical system comprises: a user-side polarizer configured to linearly polarize light associated with a world object and light associated with a virtual image along a second axis when operating according to a second state; a lens assembly coupled to the user-side polarizer and configured to apply a zero net refractive power to the light associated with the world object when the optical system is operating according to a first state, and to apply a non-zero net refractive power to the light associated with the virtual image when the optical system is operating according to a second state; and a user-side switchable waveplate positioned between two layers of the lens assembly and configured to rotate the polarization of the light associated with the virtual image by 90 degrees when the optical system is operating according to a second state.

[0007] Embodiment 3 is a method for operating an optical system, comprising the steps of: receiving light associated with a world object in the optical system; when the optical system is operating according to a first state, linearly polarizing the light associated with the world object along a first axis using one or more world-side shutter elements of the optical system; rotating the polarization of the light associated with the world object by 90 degrees using one or more world-side shutter elements; linearly polarizing the light associated with the world object along a second axis perpendicular to the first axis using one or more user-side shutter elements of the optical system; when the optical system is operating according to a second state, projecting light associated with a virtual image onto the eyepiece of the optical system using the projector of the optical system; linearly polarizing the light associated with the world object and the light associated with the virtual image along a second axis using one or more user-side shutter elements; and rotating the polarization of the light associated with the virtual image by 90 degrees using one or more user-side shutter elements.

[0008] Example 4 is the method of Example 3, further comprising the step of applying a zero net refractive power to the light associated with the world object by the lens assembly of the optical system when the optical system is operating according to the first state.

[0009] Example 5 is the method of Example 3, further comprising the step of applying a non-zero net refractive power to the light associated with the virtual image by the lens assembly of the optical system when the optical system is operating according to the second state.

[0010] Example 6 is the method of Example 3, further comprising the step of externally coupling light associated with a virtual image toward one or more user-side shutter elements by an eyepiece when the optical system is operating according to the second state.

[0011] Example 7 is the method according to Example 3, in which one or more world-side shutter elements include a world-side polarizer and a world-side switchable waveplate.

[0012] Example 8 is the method according to Example 7, in which one or more user-side shutter elements include a user-side polarizer and a user-side switchable waveplate.

[0013] Example 9 is the method according to Example 8, in which the optical system includes a lens assembly.

[0014] Example 10 is the method according to Example 9, in which the optical system operates according to a first state when the world-side switchable waveplate is electrically activated and the user-side switchable waveplate is not electrically activated.

[0015] Example 11 is the method according to Example 9, in which the optical system operates according to a second state when the user-side switchable waveplate is electrically activated and the world-side switchable waveplate is not electrically activated.

[0016] Example 12 is the method according to Example 9, in which the world-side polarizer is coupled to the world-side switchable waveplate.

[0017] Example 13 is the method according to Example 9, in which the world-side switchable waveplate is coupled to the eyepiece on the world side of the eyepiece.

[0018] Example 14 is the method according to Example 9, in which the user-side polarizer is coupled to the eyepiece on the user side of the eyepiece.

[0019] Example 15 is the method according to Example 9, in which the lens assembly is coupled to the user-side polarizer.

[0020] Example 16 is the method according to Example 9, in which the user-side switchable waveplate is positioned between two layers of the lens assembly.

[0021] Embodiment 17 is an optical system comprising: one or more world-side shutter elements configured to linearly polarize light associated with a world object along a first axis and rotate the polarization of the light associated with the world object by 90 degrees when the optical system is operating according to a first state; an eyepiece coupled to one or more world-side shutter elements; a projector configured to project light associated with a virtual image onto the eyepiece when the optical system is operating according to a second state; and one or more user-side shutter elements coupled to the eyepiece, configured to linearly polarize light associated with a world object along a second axis perpendicular to the first axis when the optical system is operating according to a first state, linearly polarize the light associated with a world object and the light associated with a virtual image along a second axis when the optical system is operating according to a second state, and rotate the polarization of the light associated with a virtual image by 90 degrees when the optical system is operating according to a second state.

[0022] Example 18 is the optical system described in Example 17, further comprising a lens assembly coupled to one or more user-side shutter elements.

[0023] Example 19 is the optical system described in Example 18, wherein the lens assembly is configured to apply zero net refractive power to the light associated with the world object when the optical system is operating according to the first state.

[0024] Example 20 is the optical system according to Example 18, wherein the lens assembly is configured to apply a non-zero net refractive power to the light associated with the virtual image when the optical system is operating according to the second state.

[0025] Example 21 is the optical system according to Example 17, wherein the eyepiece is configured to externally couple light associated with a virtual image toward one or more user-side shutter elements when the optical system is operating according to the second state.

[0026] Example 22 is the optical system described in Example 17, wherein one or more world-side shutter elements include a world-side polarizer and a world-side switchable waveplate.

[0027] Example 23 is the optical system described in Example 22, wherein one or more user-side shutter elements include a user-side polarizer and a user-side switchable waveplate.

[0028] Example 24 is the optical system described in Example 23, wherein the optical system operates according to the first state when the world-side switchable waveplate is electrically activated and the user-side switchable waveplate is not electrically activated.

[0029] Example 25 is the optical system described in Example 23, wherein the optical system operates according to a second state when the user-side switchable waveplate is electrically activated and the world-side switchable waveplate is not electrically activated.

[0030] Example 26 is the optical system described in Example 23, wherein the global polarizer is coupled to a global switchable waveplate.

[0031] Example 27 is the optical system described in Example 23, wherein the world-side switchable waveplate is coupled to the eyepiece on the world side of the eyepiece.

[0032] Example 28 is the optical system described in Example 23, wherein the user-side polarizer is coupled to the eyepiece on the user side of the eyepiece.

[0033] Example 29 is the optical system described in Example 23, wherein the lens assembly is coupled to a user-side polarizer.

[0034] Example 30 is the optical system described in Example 23, wherein a user-switchable waveplate is positioned between two layers of the lens assembly.

[0035] Embodiment 31 is a display device comprising: a waveguide assembly configured to guide light in a lateral direction parallel to the output surface of the waveguide assembly, further configured to externally couple the guided light through the output surface; and an adaptive lens assembly disposed on a first side of the waveguide assembly, which receives externally coupled light from the waveguide assembly and is configured to be selectively switched between a plurality of states having different refractive powers, wherein the adaptive lens assembly is configured to impart polarization-dependent refractive power to linearly polarized light, and the lens stack comprises a birefringent lens and an isotropic lens in contact with each other, wherein the contact surfaces of the birefringent lens and the isotropic lens form a conformal interface.

[0036] Embodiment 32 is a display device according to Embodiment 31, further comprising a second adaptive lens assembly positioned on a second side opposite to the first side of the waveguide assembly, the second adaptive lens assembly being configured to selectively switch between a plurality of states having different refractive powers and to impart polarization-dependent refractive power to linearly polarized light, the second lens stack comprising a second birefringent lens and a second isotropic lens in contact with each other, forming a conformal interface between them.

[0037] Example 33 is a display device according to Example 32, comprising a switchable half-wave plate having a twisted nematic (TN) liquid crystal (LC), the first and second adaptive lens assemblies of which are further optically coupled to a lens stack or a separate second lens stack, the switchable half-wave plate being configured to store the polarization of linearly polarized light passing through it when deactivated, and to modify the polarization of linearly polarized light passing through it when activated.

[0038] Example 34 is a display device according to Example 33, further comprising a shutter and a linear polarizer, which are configured to temporarily alternately block and pass light incident thereon on a second side opposite to the first side of the waveguide assembly.

[0039] Example 35 is a display device according to Example 34, wherein the waveguide assembly is configured to include a cholesteric liquid crystal and externally couple circularly polarized light.

[0040] Example 36 is the display device described in Example 35, wherein the waveguide assembly is interposed by a pair of quarter-wave plates.

[0041] Example 37 is an optical system comprising: a projector configured to emit light; at least one waveguide optically coupled to the projector and configured to receive light and redirect it toward a user; a shutter assembly positioned adjacent to the at least one waveguide and having at least one component, which is controllable to allow a variable amount of ambient light from the user's environment to pass through it toward the user; an adaptive lens assembly positioned between the at least one waveguide and the user, which is controllable to impart a variable amount of refractive power to the light passing through it toward the user; and a control circuit network communicatively coupled to the projector, the shutter assembly, and the adaptive lens assembly. The optical system includes a control network configured to synchronously switch between two or more states, including a first state in which a shutter assembly is configured to allow a first amount of ambient light from the user's environment to pass through it toward the user, and an adaptive lens assembly is configured to impart a first amount of refractive power to the light passing through it, and a second state in which the shutter assembly is configured to allow a second amount of ambient light from the user's environment to pass through it toward the user, and an adaptive lens assembly is configured to impart a second amount of refractive power to the light passing through it, wherein the second amount of ambient light is less than the first amount of ambient light, and the second amount of refractive power is greater than the first amount of refractive power.

[0042] Example 38 is the optical system according to Example 37, comprising a first amount of ambient light, the maximum amount of ambient light from the user's environment, configured such that the shutter assembly allows it to pass through to the user, and a first amount of refractive power, the minimum amount of refractive power, configured such that the adaptive lens assembly imparts to the light passing through it.

[0043] Example 39 is an optical system according to either Example 37 or 38, wherein in the second state, the control circuit network is configured to cause the projector to emit light representing virtual content, which will be perceived by the user as being positioned at a first depth in front of the user.

[0044] Example 40 is an optical system according to Example 39, wherein the control circuit network is configured to determine a second amount of ambient light and a second amount of refractive power based on a first depth in front of the user, where the virtual content will be perceived by the user.

[0045] Embodiment 41 is an optical system according to Embodiment 39, wherein in the first state, the control circuit network is configured to cause the projector to emit light representing virtual content that will be perceived by the user as being positioned at a second depth in front of the user, and the second depth is greater than the first depth.

[0046] Example 42 is the optical system described in Example 41, wherein the second depth is substantially equivalent to optical infinity.

[0047] Example 43 is the optical system described in Example 39, wherein in the first state, the control circuit network is configured to prevent the projector from emitting light.

[0048] Example 44 is an optical system according to either Example 37 or 38, wherein the control circuit network is configured to synchronously switch the shutter assembly and the adaptive lens assembly between two or more states at a rate greater than or equal to the minimum switching frequency.

[0049] Example 45 is the optical system described in Example 44, wherein the minimum switching frequency is 120 Hz.

[0050] Embodiment 46 is the optical system according to Embodiment 44, further comprising an ambient light sensor configured to measure the intensity of ambient light from the user's environment, wherein a control circuit network is communicatively coupled to the ambient light sensor and configured to further determine a rate at which the shutter assembly and adaptive lens assembly are synchronously switched between two or more states based on data received from the ambient light sensor.

[0051] Example 47 is the optical system described in Example 38, wherein the adaptive lens assembly is configured to impart a minimum amount of refractive power to the light passing through it, which is approximately zero.

[0052] Example 48 is an optical system according to any of the above embodiments, comprising a second amount of ambient light, a minimum amount of ambient light from the user's environment, configured therefor to allow the shutter assembly to pass through it toward the user, and a second amount of refractive power, a maximum amount of refractive power, configured therefor to impart to the light passing through it by the adaptive lens assembly.

[0053] Embodiment 49 is an optical system comprising: a projector configured to emit light; at least one waveguide optically coupled to the projector and configured to receive light and redirect it toward a user; a shutter assembly positioned adjacent to the at least one waveguide and comprising at least one component, which is controllable to allow a variable amount of ambient light from the user's environment to pass through it toward the user; an adaptive lens assembly positioned between the at least one waveguide and the user, which is controllable to impart a variable amount of refractive power to the light passing through it toward the user; and a control circuit network communicatively coupled to the projector, the shutter assembly, and the adaptive lens assembly, which is configured to synchronously vary the amount of refractive power imparted to the adaptive lens assembly toward the light passing through it toward the user, and to vary the amount of ambient light from the user's environment that is allowed to pass through it toward the user, in inverse proportion to the amount of refractive power imparted to the light passing through it by the adaptive lens assembly.

[0054] Example 50 is an optical system according to any of the above embodiments, wherein at least one waveguide is further configured to allow ambient light from the user's environment to pass through it toward the user.

[0055] Example 51 is an optical system according to any of the above embodiments, wherein at least one component of the shutter assembly is positioned between at least one waveguide and the user's environment, comprising at least one component.

[0056] Example 52 is an optical system according to any of the above embodiments, wherein at least one component of the shutter assembly is positioned between at least one waveguide and the user.

[0057] Example 53 is an optical system according to any of the above embodiments, comprising at least one component of the shutter assembly, wherein at least one component is positioned between at least one waveguide and an adaptive lens assembly.

[0058] Example 54 is an optical system according to any of the above examples, wherein at least one waveguide comprises a plurality of waveguides.

[0059] Example 55 is a non-transient computer-readable medium that stores instructions, which, when executed by one or more processors, cause one or more processors to perform at least partially any of the methods of the above embodiments.

[0060] Embodiment 56 is an optical system comprising: a projector configured to emit light; at least one waveguide optically coupled to the projector and configured to receive light and redirect it toward a user; a shutter assembly positioned adjacent to the at least one waveguide and comprising at least one component, each shutter assembly selectively switchable between different states, configured to allow different amounts of ambient light from the user's environment to pass through it toward the user; an adaptive lens assembly positioned between the at least one waveguide and the user, each adaptive lens assembly selectively switchable between different states, configured to impart different amounts of wavefront divergence to the light passing through it toward the user; and a control network communicatively coupled to the projector, the shutter assembly, and the adaptive lens assembly.

[0061] Embodiment 57 is an optical system according to Embodiment 56, wherein the control circuit network is configured to synchronously switch between two or more states at a specific rate, the two or more states being: a first state in which the shutter assembly is configured to allow a first amount of ambient light from the user's environment to pass through it toward the user, and the adaptive lens assembly is configured to impart a first amount of wavefront divergence to the light passing through it; and a second state in which the shutter assembly is configured to allow a second amount of ambient light from the user's environment to pass through it toward the user, and the adaptive lens assembly is configured to impart a second amount of wavefront divergence to the light passing through it, wherein the second amount of ambient light is different from the first amount of ambient light, and the second amount of wavefront divergence is different from the first amount of wavefront divergence.

[0062] Example 58 is the optical system described in Example 57, wherein a specific rate for synchronously switching between two or more states, the shutter assembly and the adaptive lens assembly, is a rate greater than or equal to the minimum switching frequency.

[0063] Example 59 is an optical system according to Example 57 or 58, further comprising an ambient light sensor configured to measure the intensity of ambient light from the user's environment, wherein a control circuit network is communicably coupled to the ambient light sensor and configured to further determine a specific rate for synchronously switching between two or more states based on data received from the ambient light sensor.

[0064] Example 60 is the optical system described in Example 58 or 59, wherein the minimum switching frequency is 120 Hz.

[0065] Example 61 is an optical system according to Example 57, comprising a maximum amount of ambient light from the user's environment, wherein a first amount of ambient light is configured to allow the shutter assembly to pass through it toward the user, and a minimum amount of wavefront divergence is configured to impart a first amount of wavefront divergence to the light passing through it.

[0066] Example 62 is an optical system according to either Example 57 or 61, wherein in a second state, the control circuit network is configured to cause the projector to emit light representing virtual content, which will be perceived by the user as being positioned at a first depth in front of the user.

[0067] Example 63 is an optical system according to Example 62, wherein the control circuit network is configured to determine at least one of a second amount of ambient light and a second amount of wavefront divergence based on a first depth in front of the user where the virtual content will be perceived by the user.

[0068] Embodiment 64 is an optical system according to Embodiment 62, wherein in the first state, the control circuit network is configured to cause the projector to emit light representing virtual content, which will be perceived by the user as being positioned at a second depth directly in front of the user, and the second depth is greater than the first depth.

[0069] Example 65 is the optical system described in Example 64, wherein the second depth is substantially equivalent to optical infinity.

[0070] Example 66 is the optical system described in Example 62, wherein in the first state, the control circuit network is configured to prevent the projector from emitting light.

[0071] Example 67 is the optical system described in Example 61, wherein the adaptive lens assembly is configured to impart a minimum amount of wavefront divergence to the light passing through it, which is approximately zero.

[0072] Example 68 is the optical system according to claim 57, wherein the second amount of ambient light is less than the first amount of ambient light, and the wavefront divergence of the second amount is greater than the wavefront divergence of the first amount.

[0073] Example 69 is an optical system according to any of the above examples, comprising a second amount of ambient light, a minimum amount of ambient light from the user's environment, configured therefor to allow the shutter assembly to pass through it toward the user, and a second amount of wavefront divergence, a maximum amount of wavefront divergence, configured therefor to impart to the light passing through it by the adaptive lens assembly.

[0074] Example 70 is an optical system according to Example 56, wherein the control circuit network is configured to synchronously switch the shutter assembly and the adaptive lens assembly between different states in such a way that it results in an inverse relationship between the amount of ambient light from the user's environment that is allowed to pass through it toward the user by the shutter assembly and the amount of wavefront divergence imparted to the light that passes through it toward the user toward the user by the adaptive lens assembly.

[0075] Embodiment 71 is the optical system according to Embodiment 56, wherein the control circuit network is configured to alternate between at least two different operating modes, including a first operating mode in which the control circuit network is configured to control the state of the shutter assembly and the state of the adaptive lens assembly in an asynchronous manner, and a second operating mode in which the control circuit network is configured to control the state of the shutter assembly and the state of the adaptive lens assembly in a synchronous manner.

[0076] Embodiment 72 is an optical system according to Embodiment 71, wherein in a second operating mode, the control circuit network is configured to synchronously switch between two or more states, including a first state in which the shutter assembly is configured to allow a first amount of ambient light from the user's environment to pass through it toward the user, and the adaptive lens assembly is configured to impart a first amount of wavefront divergence to the light passing through it, and a second state in which the shutter assembly is configured to allow a second amount of ambient light from the user's environment to pass through it toward the user, and the adaptive lens assembly is configured to impart a second amount of wavefront divergence to the light passing through it, wherein the second amount of ambient light is different from the first amount of ambient light, and the second amount of wavefront divergence is different from the first amount of wavefront divergence.

[0077] Embodiment 73 is an optical system according to Embodiment 71, further comprising one or more cameras configured to capture images of one or both of the user's eyes, wherein a control circuit network is further configured to be communicatively coupled to one or more cameras and to alternate between at least two different operating modes, at least in part, based on data received from one or more cameras.

[0078] Embodiment 74 is an optical system according to Embodiment 73, wherein the control circuit network is further configured to determine the depth at which the user's eye is fixated based on data received from one or more cameras, and to alternate between at least two different operating modes based at least partially on the depth at which the user's eye is determined to be fixated.

[0079] Example 75 is the optical system described in Example 71, wherein the control circuit network is further configured to cause the projector to emit light representing virtual content.

[0080] Example 76 is an optical system according to Example 75, wherein the control circuit network is configured to further determine whether the near accommodation-convergence-divergence motion mismatch with respect to the virtual content exceeds a threshold, and to alternate between at least two different operating modes in response to the determination that the near accommodation-convergence-divergence motion mismatch with respect to the virtual content exceeds a threshold.

[0081] Embodiment 77 is an optical system according to Embodiment 75, wherein the control circuit network is further configured to alternate between at least two different operating modes based on the depth in front of the user, where the virtual content will be perceived by the user.

[0082] Example 78 is the optical system according to Example 71, wherein in the first operating mode, the control circuit network is configured to keep at least one of the shutter assembly and the adaptive lens assembly in a substantially fixed state.

[0083] Example 79 is an optical system according to any of the above embodiments, wherein at least one waveguide is further configured to allow ambient light from the user's environment to pass through it toward the user.

[0084] Example 80 is an optical system according to any of the above embodiments, wherein at least one component of the shutter assembly is positioned between at least one waveguide and the user's environment.

[0085] Example 81 is an optical system according to any of the above embodiments, wherein at least one component of the shutter assembly is positioned between at least one waveguide and the user, comprising at least one component.

[0086] Example 82 is an optical system according to any of the above embodiments, wherein at least one component of the shutter assembly is positioned between at least one waveguide and an adaptive lens assembly.

[0087] Example 83 is an optical system according to any of the above embodiments, wherein at least one waveguide comprises a plurality of waveguides.

[0088] Example 84 is an optical system comprising: a projector configured to emit light; at least one waveguide optically coupled to the projector and configured to receive light and redirect it toward a user; a shutter assembly positioned adjacent to the at least one waveguide, each selectively switchable between different states, configured to allow different amounts of ambient light from the user's environment to pass through it toward the user; an adaptive lens assembly positioned between the at least one waveguide and the user, each selectively switchable between different states, configured to impart different amounts of wavefront divergence to the light passing through it toward the user; and the projector, shutter assembly, and adaptive lens. An optical system comprising a control circuit network, communicatively coupled to an assembly, configured to synchronously switch between a shutter assembly and an adaptive lens assembly at a specific rate between two or more states, the control circuit network including a first state in which the shutter assembly is configured to allow a first amount of ambient light from the user's environment to pass through it toward the user, and the adaptive lens assembly is configured to impart a first amount of wavefront divergence to the light passing through it; and a second state in which the shutter assembly is configured to allow a second amount of ambient light from the user's environment to pass through it toward the user, and the adaptive lens assembly is configured to impart a second amount of wavefront divergence to the light passing through it, wherein the second amount of ambient light is different from the first amount of ambient light, and the second amount of wavefront divergence is different from the first amount of wavefront divergence.

[0089] Example 85 is the optical system described in Example 84, wherein the second amount of ambient light is less than the first amount of ambient light, and the wavefront divergence of the second amount is greater than the wavefront divergence of the first amount.

[0090] Example 86 is the optical system described in Example 84, wherein a specific rate for synchronously switching between two or more states, the shutter assembly and the adaptive lens assembly, is a rate greater than or equal to the minimum switching frequency.

[0091] Embodiment 87 is an optical system according to Embodiment 84, wherein in the second state, the control network is configured to cause the projector to emit light representing virtual content which will be perceived by the user as being positioned at a first depth in front of the user, and the control network is configured to determine at least one of a second amount of ambient light and a second amount of wavefront divergence based on the first depth in front of the user which the virtual content will be perceived by the user.

[0092] Example 88 is the optical system according to Example 84, wherein at least one component of the shutter assembly is positioned between at least one waveguide and the user.

[0093] Embodiment 89 is an optical system comprising: a projector configured to emit light; at least one waveguide optically coupled to the projector and configured to receive light and redirect it toward a user; a shutter assembly comprising at least one component positioned adjacent to the at least one waveguide, which is controllable to allow a variable amount of ambient light from the user's environment to pass through it toward the user; an adaptive lens assembly positioned between the at least one waveguide and the user, which is controllable to impart a variable amount of wavefront divergence to the light passing through it toward the user; and a control circuit network communicatively coupled to the projector, the shutter assembly, and the adaptive lens assembly, which is configured to synchronously vary the amount of wavefront divergence imparted to the adaptive lens assembly toward the light passing through it toward the user, and to vary the amount of ambient light from the user's environment that is allowed to pass through it toward the user, in inverse proportion to the amount of wavefront divergence imparted to the light passing through it by the adaptive lens assembly.

[0094] Example 90 is an optical system comprising a projector configured to emit light, at least one waveguide optically coupled to the projector and configured to receive light and redirect it toward a user, and a shutter assembly positioned adjacent to the at least one waveguide, each shutter assembly being selectively switchable between different states, configured to allow different amounts of ambient light from the user's environment to pass through it toward the user, and an adaptive lens assembly positioned between the at least one waveguide and the user, each adaptive lens being different An optical system comprising: an adaptive lens assembly, which is selectively switchable between different states and configured to impart a certain amount of wavefront divergence to the light passing through it toward the user; and a control network communicatively coupled to a projector, a shutter assembly, and the adaptive lens assembly, the control network configured to synchronously switch the shutter assembly and the adaptive lens assembly between different states in such a way that an inverse relationship is created between the amount of ambient light from the user's environment, which is made possible by the shutter assembly to pass through it toward the user, and the amount of wavefront divergence imparted to the light passing through it toward the user by the adaptive lens assembly.

[0095] Example 91 is an optical system comprising a projector configured to emit light, at least one waveguide optically coupled to the projector and configured to receive light and redirect it toward a user, and a shutter assembly positioned adjacent to the at least one waveguide, each shutter assembly being selectively switchable between different states, configured to allow different amounts of ambient light from the user's environment to pass through it toward the user, and an adaptive lens assembly positioned between the at least one waveguide and the user, each adaptive lens An optical system comprising: an adaptive lens assembly, which is selectively switchable between different states, configured to impart different amounts of wavefront divergence to light passing through it toward the user; and a control network, which is communicatively coupled to a projector, a shutter assembly, and the adaptive lens assembly, and is configured to alternate between at least two different operating modes, including a first operating mode in which the control network is configured to control the state of the shutter assembly and the state of the adaptive lens assembly in an asynchronous manner, and a second operating mode in which the control network is configured to control the state of the shutter assembly and the state of the adaptive lens assembly in a synchronous manner.

[0096] Embodiment 92 is a non-transient computer-readable medium that stores instructions, which, when executed by one or more processors, causes one or more processors to perform one or more of the operations performed by the control circuit network of any of the embodiments described above.

[0097] Numerous advantages over conventional techniques are achieved by the methods of this disclosure. Various embodiments described herein provide a compact, time-multiplexed display capable of applying refractive power to virtual image light such that world light remains undistorted while simultaneously providing virtual content at various depths. Various embodiments described herein also provide adaptive lens assemblies, including polarization-selective lens stacks. In one implementation, the polarization-selective lens stack comprises birefringent lenses, e.g., Fresnel birefringent lenses, and isotropic lenses in contact with each other. Such assemblies can be compact (e.g., they can have reduced thickness) and / or lightweight. These assemblies can also potentially offer various advantageous optical functionalities such as high bandwidth, increased switching speed, reduced chromatic aberration, increased ease of matching, and / or variable refractive power. Some embodiments of this disclosure offer to replace conventional front adaptive lens assemblies and shutter assemblies, resulting in smaller / lighter form factors and increased power savings. In addition, the various embodiments described herein can provide adaptive lens assemblies with relatively low levels of light leakage, which could otherwise lead to “afterimage” images. Other advantages of this disclosure will be readily apparent to those skilled in the art. [Brief explanation of the drawing]

[0098] [Figure 1] Figure 1 illustrates an augmented reality (AR) scene as viewed through a wearable AR device, according to an embodiment described herein.

[0099] [Figure 2] Figure 2 illustrates an embodiment of a display system comprising a pair of adaptive lens assemblies.

[0100] [Figure 3]Figure 3A illustrates an embodiment of the display system in Figure 2 that uses adaptive lenses to display virtual content to the user in a virtual depth plane. Figure 3B illustrates an embodiment of the display system in Figure 2 that provides the user with a view of real-world content through adaptive lenses.

[0101] [Figure 4A] Figures 4A-4C illustrate one or more general features of an AR device as described herein. [Figure 4B] Figures 4A-4C illustrate one or more general features of an AR device as described herein. [Figure 4C] Figures 4A-4C illustrate one or more general features of an AR device as described herein.

[0102] [Figure 5] Figure 5 illustrates a schematic diagram of the wearable AR device described herein.

[0103] [Figure 6] Figure 6A shows a cross-sectional view of an exemplary polarization-selective lens stack comprising a birefringent lens and an isotropic lens. Figure 6B shows the polarization-selective lens stack of Figure 6A in operation, where linearly polarized light passing through it has a first polarization. Figure 6C shows the polarization-selective lens stack of Figure 6A in operation, where linearly polarized light passing through it has a second polarization.

[0104] [Figure 7] Figure 7A illustrates the polarization-selective lens stack of Figure 6A with annotated parameters. Figure 7B illustrates cross-sectional and top-and-bottom views of an embodiment of the polarization-selective lens stack comprising a birefringent Fresnel lens and an isotropic lens.

[0105] [Figure 8]Figure 8A shows a cross-sectional view of an exemplary adaptive lens assembly comprising a polarization-selective lens stack coupled with a switchable waveplate having a torsion nematic liquid crystal. Figure 8B shows the switchable waveplate having a torsion nematic liquid crystal in the adaptive lens assembly shown in Figure 8A.

[0106] [Figure 9A] Figure 9A shows a cross-sectional view of an exemplary adaptive lens assembly comprising a first polarization-selective lens stack coupled to a first switchable waveplate having a torsion nematic liquid crystal, and a second polarization-selective lens stack coupled to a second switchable waveplate having a torsion nematic liquid crystal.

[0107] [Figure 9B] Figures 9B–9E illustrate exemplary adaptive lens assemblies of Figure 9A in operation under different configurations, configured to impart different refractive forces. [Figure 9C] Figures 9B–9E illustrate exemplary adaptive lens assemblies of Figure 9A in operation under different configurations, configured to impart different refractive forces. [Figure 9D] Figures 9B–9E illustrate exemplary adaptive lens assemblies of Figure 9A in operation under different configurations, configured to impart different refractive forces. [Figure 9E] Figures 9B–9E illustrate exemplary adaptive lens assemblies of Figure 9A in operation under different configurations, configured to impart different refractive forces.

[0108] [Figure 10] Figure 10 illustrates a cross-sectional view of an exemplary display device, comprising a waveguide assembly interposed between a first adaptive lens assembly and a second adaptive assembly, each having a polarization-selective lens stack.

[0109] [Figure 11A]Figure 11A illustrates a cross-sectional view of an exemplary display device comprising a waveguide assembly interposed between an adaptive assembly having a shutter and linear polarizer on a first side and a polarization-selective lens stack on a second side.

[0110] [Figure 11B] Figure 11B illustrates the waveguide assembly of the display device shown in Figure 11A, which includes a cholesteric liquid crystal and is configured to externally couple circularly polarized light.

[0111] [Figure 11C] Figure 11C illustrates the exemplary display device shown in Figure 11A in operation, configured for viewing a world image.

[0112] [Figure 11D] Figure 11D illustrates the exemplary display device shown in Figure 11A in operation, configured for viewing virtual images.

[0113] [Figure 12A] Figure 12A illustrates an embodiment of a display device having a single adaptive lens assembly on the user side of the eyepiece, according to some embodiments of the present disclosure.

[0114] [Figure 12B] Figure 12B illustrates an embodiment of a display device operating according to a first state, according to some embodiments of the present disclosure.

[0115] [Figure 12C] Figure 12C illustrates an embodiment of a display device operating according to a second state, according to some embodiments of the present disclosure.

[0116] [Figure 13] Figure 13 illustrates a method for operating an optical system according to several embodiments of the present disclosure.

[0117] [Figure 14] Figure 14 illustrates how to operate an optical system according to some embodiments of the present disclosure.

[0118] [Figure 15] Figure 15 illustrates exemplary embodiments of a method for operating an optical system according to some embodiments of the present disclosure.

[0119] [Figure 16A] Figure 16A illustrates an embodiment of a display device operating according to a first state, according to some embodiments of the present disclosure.

[0120] [Figure 16B] Figure 16B illustrates an embodiment of a display device operating according to a second state, according to some embodiments of the present disclosure.

[0121] [Figure 16C] Figure 16C illustrates an embodiment of a display device operating according to a third state, according to some embodiments of the present disclosure.

[0122] [Figure 17] Figure 17 illustrates a simplified computer system according to an embodiment described herein. [Modes for carrying out the invention]

[0123] Optical see-through (OST) augmented reality (AR) devices can enhance virtual content presented to a user by applying refractive power to virtual image light (i.e., light associated with a virtual image) using one or more adaptive lens assemblies arranged within an optical stack. One problem with such configurations is that the refractive power is also applied to world light (i.e., light associated with world objects) passing through it, causing distortion of perceived world objects and thereby reducing the user experience. Several embodiments described herein overcome these and other problems by providing various shutter elements arranged within an optical stack that can be sequentially activated to produce the result that world light passes through the AR device without distortion, and virtual image light is, if necessary, given refractive power from the adaptive lens assemblies.

[0124] Figure 1 illustrates an AR scene as viewed through a wearable AR device according to an embodiment described herein. AR scene 100 is depicted, and the user of the AR technology sees a real-world park-like setting 106 featuring people, trees, buildings in the background, and a concrete platform 120. In addition to these items, the user of the AR technology also perceives "seeing" a robotic figure 110 standing on the real-world platform 120 and a flying cartoonish avatar character 102 that appears to be a personification of a bumblebee, although these elements (character 102 and figure 110) do not exist in the real world. Due to the significant complexity of human visual perception and the nervous system, producing virtual reality (VR) or AR technologies that facilitate a comfortable, natural, and rich presentation of virtual image elements among other virtual or real-world image elements is challenging.

[0125] Figure 2 illustrates an embodiment of a display device 200, such as a wearable display device, comprising one or more adaptive lens assemblies, including a polarization-selective lens stack, for example, a pair of adaptive lens assemblies 204, 208, in an optical path 216 interposed by a waveguide assembly 212. As described herein, the waveguide assembly 212 may include a waveguide configured to propagate light (e.g., visible light) under total internal reflection and to externally couple the light in an optical axis extending from the optical output surface of the waveguide (e.g., the main surface of the waveguide) (e.g., in the direction normal thereto). In some embodiments, the light may be externally coupled by a diffraction grating. Each of the adaptive lens assemblies 204, 208 may be configured, at least partially, to transmit the externally coupled light through it. In the illustrated embodiment, each of the adaptive lens assemblies 204, 208 may receive the externally coupled light from the waveguide assembly 212 and be configured to focus or diverge the externally coupled light in the optical axis direction. Each adaptive lens assembly 204, 208 comprises a polarization-selective lens stack comprising a birefringent lens and an isotropic lens in contact with each other, the contact surfaces of the birefringent lens and the isotropic lens forming a conformal interface between them. Each adaptive lens assembly 204, 208 is configured to be selectively switched between multiple states having different refractive powers. That is, each adaptive lens assembly 204, 208 is configured to be selectively switched between multiple states in which the individual adaptive lens assembly is configured to impart different amounts of wavefront divergence or convergence to the light passing through it. Each adaptive lens assembly 204, 208 can further be configured to modify the polarization state of externally coupled light passing through it when activated (e.g., electrically activated).

[0126] As used herein, an adaptive lens assembly refers to a lens assembly having at least one optical property that can be tuned, for example, reversibly activated and deactivated using an external stimulus. Exemplary optical properties that can be reversibly activated and deactivated include, among other things, refractive power (focal length), phase, polarization, polarization selectivity, transmittance, reflectance, birefringence, and diffraction properties. In various embodiments, an adaptive lens assembly is capable of electrically varying the refractive power and polarization state of light passing through it.

[0127] In the illustrated embodiment, each pair of adaptive lens assemblies 204 and 208 is configured to be selectively switchable between at least two states, in the first state, each is configured to allow externally coupled light to pass through it without altering its polarization state, while in the second state, each is configured to alter the polarization state of the externally coupled light passing through it. For example, in the second state, each adaptive lens assembly 204 and 208 reverses the polarity of circularly polarized light, while in the first state, each adaptive lens assembly 204 and 208 preserves the polarity of circularly polarized light.

[0128] Still referring to Figure 2, the display device 200 may further include a waveguide assembly 212 interposed between a pair of adaptive lens assemblies 204, 208. Each of the waveguide assemblies 204, 208 may be configured to propagate light under total internal reflection in a lateral direction parallel to the main surface of the waveguide. Each of the waveguide assemblies 204, 208 may further be configured to externally couple light, for example, in a direction normal to the main surface of the waveguide.

[0129] Still referring to Figure 2, the first adaptive lens assembly 204 of the paired adaptive lens assembly is positioned on the first side of the waveguide assembly 212, for example, on the side of the world observed by the user, and the second adaptive lens assembly 208 of the paired lens assembly is positioned on the second side of the waveguide assembly 212, for example, on the side of the user's eye. As described below, the paired adaptive lens assemblies 204, 208 are configured to provide the user with virtual content from the waveguide assembly 212 into multiple virtual depth planes, as well as a real-world view. In some embodiments, there is little to no distortion due to the presence of the paired adaptive lens assemblies 204, 208. The real-world virtual content and view are provided to the user in response to the activation of the first and second adaptive lens assemblies 204, 208, as described below with reference to Figures 3A and 3B.

[0130] Figures 3A and 3B illustrate embodiments of display devices 300A and 300B, each comprising an adaptive lens assembly for outputting image information to the user during operation. Display devices 300A and 300B may correspond to the same display device at different times and / or different states. In some embodiments, display devices 300A and 300B are structurally identical in the unpowered state. Display device 300A is used herein to describe the step of outputting a virtual image to the user, while display device 300B is used herein to describe the step of transmitting a real-world image to the user through display device 300B. Display devices 300A and 300B include a pair of adaptive lens assemblies 204 and 208 configured to be electrically activated, for example, by the application of voltage or current. In some embodiments, in the deactivated state, for example, when no voltage or current is applied, the first and second adaptive lens assemblies 204 and 208 each have low refractive power, e.g., about zero. In some embodiments, when activated, for example, when a voltage or current is applied, the first adaptive lens assembly 204 on the world side has a first sign, for example, a first net refractive power (P) with a positive refractive power. net1 ) may provide. When activated, the second adaptive lens assembly 208 on the user's side provides a second sign, for example, a second net refractive power (P) with a negative refractive power. net2 ) may be provided. However, embodiments are not limited thereto, and in other embodiments, the first and second adaptive lens assemblies 200A, 200B may provide refractive power when deactivated, while providing substantially zero refractive power when activated.

[0131] Figure 3A illustrates an embodiment of the display system of Figure 2, which displays virtual content to the user in a virtual depth plane 304, according to several embodiments. As described above, a waveguide assembly 212 interposed between a pair of adaptive lens assemblies 204, 208 comprises a waveguide configured to receive light containing virtual image information and propagate the light under total internal reflection. The waveguide assembly 212 is further configured to externally couple the light toward the user's eye, for example, through a diffraction grating. The externally coupled light passes through the user-side adaptive lens assembly 208 prior to entering the user's eye. When activated, the user-side adaptive lens assembly 208 has a second net refractive power P net2 It has a value that can be negative, so that the user can see a virtual image in the virtual depth plane 304.

[0132] In some embodiments, the second net refractive power P net2 The second net refractive power (P) of the user-adaptive lens assembly 208 is electrically regulated. net2 The second net refractive power P of the user-side adaptive lens assembly 208 may be adjusted to adjust the distance to the virtual depth plane 304. For example, as the virtual object "moves" closer to and further away from the user's eye in the virtual three-dimensional space, the second net refractive power P of the user-side adaptive lens assembly 208 may be adjusted. net2 The virtual depth plane 304 may be adjusted accordingly to adjust to track the virtual object. Thus, the user will not experience relatively little or no near-or far-or-far accommodation / convergence-divergence motion mismatch beyond an acceptable threshold. In some embodiments, the magnitude of the distance to the virtual depth plane 304 may be adjusted in discrete steps, while in some other embodiments, the magnitude of the distance to the virtual depth plane 304 may be adjusted continuously.

[0133] FIG. 3B illustrates an example of the display system of FIG. 2 that provides a view of real-world content to a user, according to some embodiments. The user-side adaptive lens assembly 208 is activated and has a second net refractive power (P net2 ) to display virtual content on the virtual depth plane 304. Light from the real world passing through the user-side adaptive lens assembly 208 can also be converged or diverged according to the P net2 of the user-side adaptive lens assembly 208 that is activated. Thus, objects in the real world can appear out of focus or distorted. To reduce such distortion, according to embodiments, when activated, the adaptive lens assemblies 204, 208 may be configured to have refractive powers with opposite signs. In some embodiments, the light passing through the adaptive lens assemblies 204, 208 converges or diverges according to a combined refractive power having a magnitude that is approximately the difference between the magnitudes of the first and second net refractive powers P net1 , P net2 of the world-side and user-side adaptive lens assemblies 204, 208, respectively. In some embodiments, the waveguide assembly 212 may also have a refractive power, and the adaptive lens assembly 208 may be configured to account for the distortion caused by both the lens assembly 204 and the waveguide assembly 212. For example, the refractive power of the adaptive lens assembly 208 may be of the opposite sign to the sum of the refractive powers of the adaptive lens assembly 204 and the waveguide assembly 212.

[0134] In some embodiments, the world-side adaptive lens assembly 204 is configured to have a first net refractive power P net2 that is close to or the same magnitude as the magnitude of the second net refractive power P net1 of the user-side adaptive lens assembly 208 but with an opposite sign. As a result, when both the adaptive lens assemblies 204, 208 are activated, objects in the real world appear relatively unaffected by the refractive power of the user-side adaptive lens assembly 208 provided to display virtual content.

[0135] In some embodiments, when the first adaptive lens assembly 204 is activated, the first net refractive power P net1 However, the second net refractive power P of the user-adaptive lens assembly 208 net2 It may be configured to dynamically match. For example, the second net refractive power P of the user-side adaptive lens assembly 208 net2 However, as the world-side adaptive lens assembly 204 is adjusted to track virtual objects moving in a virtual 3D space, the first net refractive power P net1 The combined refractive power P = P net1 +P net2 The magnitude may be dynamically adjusted so that it can be kept below a predetermined value. Thus, according to the embodiment, an object in the real world has a combined refractive power P=P net1 +P net2 The first net refractive power (P) of the world-side adaptive lens assembly 204 remains small. net1 ) along with the second net refractive power (P) of the user-adaptive lens assembly 208, which may have a negative value. net2 By compensating for this, it is possible to prevent unacceptable out-of-focus rendering. As will be described in more detail below, in some implementations, the wearable display device may include a waveguide assembly and a user-side adaptive lens assembly, each functionally equivalent to or similar to the waveguide assembly 212 and the user-side adaptive lens assembly 208, but not including a world-side adaptive lens assembly similar to that of the world-side adaptive lens assembly 204. Alternatively, as will be described in more detail below, in these implementations, the display device may include one or more shutter elements and may be configured to control one or more such shutter elements, synchronized with the user-side adaptive lens, so that objects in the real world are not rendered unacceptably out of focus due to the refractive force imparted by the user-side adaptive lens.

[0136] Figure 4A illustrates one or more general features of the AR device 400 as disclosed herein. As shown in Figure 4A, the AR device 400 includes an eyepiece 402 and an adaptive lens assembly 405, which may be functionally equivalent to or similar to the waveguide assembly 212 and the user-side adaptive lens assembly 208, respectively, as described above. During operation, the projector 414 of the AR device 400 may project virtual image light 423 (i.e., light associated with a virtual image) onto the eyepiece 402, which may project a light field (i.e., an angular representation of the virtual content) onto the user's retina so that the user perceives the corresponding virtual content as being located in a place in the user's environment. For example, the user may perceive a character 102 as being located in or near a first virtual depth, and an image 110 as being located in or near a second virtual depth. The AR device 400 may include only one adaptive lens assembly 405 (for example, positioned on the user side of the eyepiece 402, i.e., on the side of the eyepiece 402 closest to the user's eye), but such an adaptive lens assembly may be capable of imparting multiple different non-zero refractive forces to the light passing through it. That is, the adaptive lens assembly 405 may be capable of imparting at least one of multiple different amounts of wavefront divergence and collimation to the light passing through it.

[0137] The AR device 400 may also include one or more shutter elements 403 coupled to the world side (the side of the eyepiece 402 furthest from the user's eye and closest to the world object 430) and / or the user side of the eyepiece 402. World light 432, associated with the world object 430, may pass through the AR device 400 with a zero net refractive force applied by the lens assembly 405 by sequentially electrically activating different elements / layers of the shutter element 403 as described herein, and virtual image light 423 may pass through it with a non-zero (e.g., negative) net refractive force applied by the lens assembly 405. Exemplary dimming components representing, or potentially included in, shutter element 403 and other shutter assemblies described herein are described in U.S. Patent Application No. 62 / 725,993 (Patent Attorney No. 101782-005600US-1083563) filed August 31, 2018, U.S. Patent Application No. 16 / 557,706 filed August 30, 2019, and International Patent Application No. PCT / US2019 / 051188 filed September 13, 2019 (all of which are incorporated herein by reference as a whole).

[0138] In some embodiments, the AR device 400 may include an ambient light sensor 434 configured to detect world light 432. The ambient light sensor 434 may be positioned to resemble and / or represent the world light 432 that the world light 432 detected by the ambient light sensor 434 strikes on the AR device 400 (e.g., the shutter element 403, the eyepiece 402, and / or lens assembly 405). In some embodiments, the ambient light sensor 434 may be configured to detect multiple spatially resolved light values ​​corresponding to different pixels in the field of view of the AR device 400. In some embodiments, or identical embodiments, the ambient light sensor 434 may be configured to detect a global light value corresponding to the average or single light intensity of world light 432. The detected ambient light may be used by the AR device 400 to determine the shutter frequency, which the AR device 400 alternates between operating according to a first state or a second state. In some instances, the shutter frequency may exceed the flicker fusion threshold so that the shutter is not easily perceptible to the user. For example, the shutter frequency may be at least 120 Hz (e.g., 160 Hz or 200 Hz).

[0139] Figure 4B illustrates an AR device 400 operating according to a first state, according to some embodiments of the present disclosure. While operating according to the first state, the projector 414 is turned off and one or more of the shutter elements 403 are electrically activated so that world light 432 passes through the AR device 400 with zero net refractive power applied by the lens assembly 405. This is accomplished using a world-side polarizer of the shutter element 403 for linearly polarizing the world light 432 along a first axis, a world-side switchable waveplate of the shutter element 403 for rotating the polarization of the world light 432 by 90 degrees, and a user-side polarizer of the shutter element 403 for linearly polarizing the world light 432 along a second axis perpendicular to the first axis.

[0140] In some embodiments, one or more components of the shutter element 403 are considered subcomponents of the lens assembly 405 (i.e., considered to be contained within the lens assembly 405). For example, the user-side polarizer of the shutter element 403 may be considered a subcomponent of the lens assembly 405. In such embodiments, when the AR device 400 is operating according to a first state, the lens assembly 405 is considered to be switched to a state in which a zero refractive force is applied to the light passing through it, activated, and / or controlled.

[0141] Figure 4C illustrates an AR device 400 operating according to a second state, according to some embodiments of the present disclosure. When operating according to the second state, the projector 414 is turned on and one or more of the shutter elements 403 are electrically activated so that the world light 432 is completely or at least partially reduced, blocked, or dimmed, and the virtual image light 423 passes through the AR device 400 with a non-zero net refractive power applied by the lens assembly 405. This is accomplished using a world-side polarizer of the shutter element 403 for linearly polarizing the world light 432 along a first axis, a user-side polarizer of the shutter element 403 for linearly polarizing the world light 432 and the virtual image light 423 along a second axis perpendicular to the first axis, and a user-side switchable waveplate of the shutter element 403 for rotating the polarization of the virtual image light 423 by 90 degrees.

[0142] As illustrated with reference to Figure 4B, in some embodiments, one or more components of the shutter element 403 are considered subcomponents of the lens assembly 405 (i.e., considered to be contained within the lens assembly 405). For example, the user-side polarizer of the shutter element 403 may be considered a subcomponent of the lens assembly 405. In such embodiments, when the AR device 400 is operating according to a second state, the lens assembly 405 is considered to be switched, activated, and / or controlled to apply a non-zero refractive force to the light passing through it. In some embodiments (for example, as illustrated with reference to Figures 11C and 11D), the polarizing eyepiece may also be switched, activated, and / or controlled with each state so that the refractive force applied to the light it externally couples can vary.

[0143] Figure 5 illustrates a schematic diagram of a wearable AR device 500 according to this disclosure. The AR device 500 may include a left eyepiece 502A, a left shutter element 503A, and a left lens assembly 505A, arranged in a juxtaposed configuration, and a right eyepiece 502B, a right shutter element 503B, and a right lens assembly 505B, similarly arranged in a juxtaposed configuration. In some embodiments, the AR device 500 includes, but is not limited to, one or more sensors, including a left-facing world camera 506A mounted directly to or near the left eyepiece 502A, a right-facing world camera 506B mounted directly to or near the right eyepiece 502B, a left-facing world camera 506C mounted directly to or near the left eyepiece 502A, a right-facing world camera 506D mounted directly to or near the right eyepiece 502B, a left-eye tracker positioned to observe the user's left eye, a right-eye tracker positioned to observe the user's right eye, and an ambient light sensor 534. In some embodiments, the AR device 500 includes one or more image projection devices, such as a left projector 514A optically linked to the left eyepiece 502A, and a right projector 514B optically linked to the right eyepiece 502B.

[0144] Some or all of the components of the AR device 500 may be mounted on the head so that the projected image can be viewed by the user. In one particular implementation, all of the components of the AR device 500 shown in Figure 5 are mounted on a single device (e.g., a single headset) that can be worn by the user. In another implementation, one or more components of the processing module 550 are physically separate from the other components of the AR device 500 and are communicatively coupled to them by one or more wired and / or wireless connections. For example, the processing module 550 may include a local module 552 on the head-mounted portion of the AR device 500 and a remote module 556 that is physically separate and communicatively linked to the local module 552. The remote module 556 may be mounted in various configurations, such as being fixed to a frame, fixed to a helmet or hat worn by the user, built into headphones, or otherwise removable by the user (e.g., in a backpack configuration, in a belt-mounted configuration, etc.).

[0145] The processing module 550 may include a processor and associated digital memory such as non-volatile memory (e.g., flash memory), both of which may be used to assist in data processing, caching, and storage. The data may include data captured from sensors such as a camera 506, an ambient light sensor 534, an eye tracker, a microphone, an inertial measurement unit, an accelerometer, a compass, a GPS unit, a wireless device, and / or a gyroscope (e.g., operably coupled to the AR device 500 or otherwise attached to the user). For example, the processing module 550 may receive an image 520 from the camera 506. Specifically, the processing module 550 may receive a left front image 520A from a left-facing world camera 506A, a right front image 520B from a right-facing world camera 506B, a left-side image 520C from a left-facing world camera 506C, and a right-side image 520D from a right-facing world camera 506D. In some embodiments, the image 520 may include a single image, a pair of images, a video comprising a stream of images, a video comprising a stream of paired images, and equivalents. The image 520 may be generated periodically while the AR device 500 is powered on and transmitted to the processing module 550, or generated in response to a command transmitted by the processing module 550 to one or more of the cameras. In another embodiment, the processing module 550 may receive ambient light information from the ambient light sensor 534. In another embodiment, the processing module 550 may receive gaze information from the eye tracker. In another embodiment, the processing module 550 may receive image information (e.g., image brightness values) from one or both of the projectors 514.

[0146] The eyepieces 502A and 502B may each include a transparent or translucent waveguide configured to direct and externally couple light from the projectors 514A and 514B, respectively. Specifically, the processing module 550 may cause the left projector 514A to output the left virtual image light 522A onto the left eyepiece 502A, and the right projector 514B to output the right virtual image light 522B onto the right eyepiece 502B. In some embodiments, each eyepiece 502 may include multiple waveguides corresponding to different colors and / or different depth planes. In some embodiments, the shutter element 503 may be coupled to and / or integrated with the eyepiece 502. For example, the shutter element 503 may be incorporated into a multilayer eyepiece and may form one or more layers constituting one of the eyepieces 502. In some embodiments, the processing module may electrically activate the shutter elements 503A and 503B using a left shutter control signal 519A and a right shutter control signal 519B, respectively. For example, the processing module 550 may apply different voltages to the shutter control signal 519 to alternate the AR device 500 between steps of presenting world light and virtual image light to the user.

[0147] Cameras 506A and 506B may be positioned to capture images that substantially overlap with the field of view of the user's left and right eyes, respectively. Therefore, the placement of camera 506 may be close to the user's eyes, but not so close that it obscures the user's field of view. Alternatively, or in addition, cameras 506A and 506B may be positioned to align with the internal coupling locations of virtual image beams 522A and 522B, respectively. Cameras 506C and 506D may be positioned, for example, to capture images on the user's side within or outside the user's peripheral vision. Images 520C and 520D captured using cameras 506C and 506D do not necessarily have to overlap with images 520A and 520B captured using cameras 506A and 506B. Polarization-selective lens stack with birefringent and isotropic lenses for adaptive lens assemblies

[0148] Various embodiments described herein provide adaptive lens assemblies comprising a polarization-selective lens stack. In one implementation, the polarization-selective lens stack comprises a birefringent lens, such as a Fresnel birefringent lens, and an isotropic lens, in contact with each other. Such assemblies can be compact (e.g., they can have reduced thickness) and / or lightweight. These assemblies can also potentially provide various advantageous optical functionalities such as high bandwidth, increased switching speed, reduced chromatic aberration, increased ease of matching, and / or variable refractive power. In addition, various embodiments described herein can provide adaptive lens assemblies with relatively low amounts of light leakage, which could otherwise lead to “afterimage” images. According to various embodiments, the adaptive assembly comprises a polarization-selective lens stack comprising a birefringent lens and an isotropic lens, as described herein.

[0149] Referring to Figure 6A, to provide images to multiple depth planes with high efficiency over a wide range of the visible spectrum, adaptive lens assemblies according to various embodiments include a polarization-selective lens stack 600 configured to impart polarization-dependent refractive power to linearly polarized light. The polarization-selective lens stack 600 may include a birefringent lens 604 having an optical axis 602 extending in a lateral direction perpendicular to the direction of light propagation, for example, the z-direction, for example, in the x-direction or y-direction. The birefringent lens 604 has a birefringence Δn, where the birefringence Δn is the anomalous refractive index n of the birefringent lens 604. e and normal refractive index n o This corresponds to the difference between the two. The birefringent lens 604 may have a radius of curvature R1 such that it is configured to impart a first refractive power p1 to light passing through it and having polarization parallel to the optical system axis, and a second refractive power p2 to light passing through it and having polarization perpendicular to the optical system axis.

[0150] Polarization-selective lens stack 600 also has a refractive index n cThe present invention may include an isotropic lens 608 having a second radius of curvature R2, which is configured to impart to the light passing through it a first refractive power p1 and a third refractive power p3 having the opposite sign to the second refractive power p2.

[0151] In the illustrated embodiment, the anomalous refractive index n of the isotropic lens 608 is, but is not limited to, e The normal refractive index n of the birefringent lens 604 o It has substantially the same value as [another value]. However, the anomalous refractive index n e In some other embodiments, the refractive index is typically n o Please understand that this may differ from the previous statement.

[0152] In the illustrated embodiment, though not limited, the first radius of curvature R1 and the second radius of curvature R2 are R, which are substantially the same in magnitude but have opposite signs. Furthermore, because R1 and R2 are substantially the same in magnitude, the birefringent lens 604 and the isotropic lens 608 are in continuous contact along the interface having a radius of curvature R. That is, the contact surfaces of the birefringent lens 604 and the isotropic lens 608 form a conformal interface between them.

[0153] Referring to Figure 6B, the polarization-selective lens stack 600 in operation is shown when the incident light 612, for example, linearly polarized light, has a polarization direction parallel to the direction of the optical system axis 602. Under these conditions, the light passing through the birefringent lens 604 has an anomalous refractive index n e The light passing through the isotropic lens 608, which is subject to the refractive index corresponding to n, normally has a refractive index of n. o Because it is subjected to the corresponding refractive index, the lens stack 600 imparts a refractive force to the light, which can be expressed as follows: [ka] In the formula, R represents the radius of the birefringent lens 604 and the isotropic lens 608.

[0154] Referring to Figure 6C, the polarization-selective lens stack 600 in operation is shown when the incident light 616, for example, linearly polarized light, has a polarization direction perpendicular to the direction of the optical axis 602. Under these conditions, the light passing through the birefringent lens 604 has a refractive index n o The lens stack 600 imparts a refractive power to the light, which corresponds to the refractive index of the light passing through the isotropic lens 608, and this is identical to the refractive index of the light passing through the isotropic lens 608, so that the lens stack 600 imparts a refractive power that can be expressed as follows: [ka] In the formula, R represents the radius of the birefringent lens 604 and the isotropic lens 608.

[0155] Referring still to Figures 6A-6C, in some embodiments the isotropic lens 608 may be formed from an isotropic material, such as glass or acrylic. On the other hand, the birefringent lens 604 may be formed from or consist of a birefringent material, such as liquid crystal, according to various embodiments. For example, the birefringent lens 604 may comprise a transparent substrate, such as a glass substrate, having liquid crystal (LC) molecules formed thereon, which are extended along a lateral direction (e.g., x-direction or y-direction) perpendicular to the light propagation direction (e.g., z-direction).

[0156] However, the embodiments are not limited in this way, and in other embodiments, the birefringent lens 604 may be formed from or made from a suitable birefringent material other than LC. For example, the birefringent lens 604 may include, to name a few, BaB2O4, Be3Al2(SiO3)6, CaCO3, LiNbO3, TiO2, SiC, tourmaline, and ZrSiO4. Polarization-selective lens stack with birefringent Fresnel lenses and isotropic lenses for adaptive lens assemblies

[0157] As described above with respect to Figures 6A-6C, a lens stack comprising a birefringent lens, for example, an LC-based birefringent lens, and an isotropic lens can provide a polarization-selective lens effect. Below, a polarization-selective lens stack comprising a liquid crystal-based birefringent lens configured as a Fresnel lens will be described.

[0158] A Fresnel lens may, for example, comprise a thin plate-type lens, which features a fractional prism-like structure formed by dividing a conventional curved (e.g., spherical) lens into a set of sections, such as concentric annular sections known as Fresnel zones. The Fresnel zones replace the sustained curvature of a sustained refractive lens with a set of identically shaped surfaces having discontinuity between them. A substantial reduction in thickness can be achieved by employing such fractional sections, allowing lenses with relatively large apertures to be manufactured using smaller volumes of material.

[0159] Figure 7A illustrates a cross-sectional side view of the lens stack 600 described above with respect to Figures 6A-6C, annotated with relevant optical dimensions, including the distance R from the focal point to a given location on the birefringent lens 604, the radial distance A from the central axis (e.g., optical axis) of the lens stack 600 to a given location, the angle θ defined by distance R and A, and the thickness d of the curved portion of the birefringent lens 604. As described above, in various implementations, the birefringent lens 604 and the isotropic lens 608 have substantially the same radius of curvature, and therefore the birefringent lens 604 and the isotropic lens 608 are in continuous contact along the interface formed between them, which has a radius of curvature R.

[0160] Figure 7B shows a cross-sectional side view 700A (top) and a cross-sectional view 700B (bottom) of a lens stack 700 comprising a birefringent Fresnel lens 704 and a corresponding lens, such as an isotropic Fresnel lens 708. By employing the Fresnel lens 704, the groove thickness d' of the curved portion of the birefringent lens 704 can be substantially reduced. Despite the substantially reduced thickness d', the lens stack 700 has a corresponding curvature, such as an effective radius of curvature R, which corresponds to the actual radius of curvature R of a conventional lens illustrated with respect to Figure 7A. Therefore, although not shown, the lens stack 700A also has a radial distance A of the Fresnel zone or groove 706 from the central axis of the lens stack 700. k and distance R and A k It has an angle θ defined by the . In some implementations, such as the one shown in Figure 7B, despite the groove separating the Fresnel zones, the birefringent Fresnel lens 704 and the isotropic lens 708 are in continuous contact through the entire interface formed between them, having an effective radius of curvature R. In some embodiments, the continuous Fresnel zone in the radially outward direction is separated by a different radial distance A k The distance between adjacent grooves 706 can be different. For example, in the illustrated embodiment, the distance between adjacent Fresnel zones is smaller in the radially outward direction of the birefringent Fresnel lens 704. However, embodiments are not limited in this way, and in other embodiments, the radial distance A of the continuous Fresnel zones may be different. k This can provide an optical effect similar to or identical to the illustrated embodiment, with each zone having a different groove thickness, while increasing linearly with a constant distance between adjacent Fresnel zones.

[0161] Referring to Figure 7B (below), the illustrated birefringent Fresnel lens 704 comprises, according to some embodiments, a plurality of concentric Fresnel zones. The birefringent Fresnel lens 704 has a radius A kThe lens has multiple grooves 716 that form the boundaries of the Fresnel zone 712 at a distance from the central axis represented by . According to various embodiments, the groove thickness d' of the birefringent lens 704 is designed such that the path length is a multiple of the design wavelength λ. This arrangement can create a 2 nm phase jump between zones that connects to the same wavefront. The value of d' can be selected (e.g., optimized) to balance the machining tolerance and reduce or minimize aberrations that may arise from the sharp edges of the grooves 716. In one embodiment, the radius R of the k-th Fresnel zone can be calculated by setting the thickness of the curved region to kd' using the following equation: [ka] In the formula, k represents the number of Fresnel zones counted from the center of the lens, and the groove thickness d' is constant across the surface of the illustrated birefringent Fresnel lens 704.

[0162] In some embodiments, the birefringent Fresnel lens 704 contains LC molecules. The LC molecules may have an elongation direction that is aligned laterally or substantially extends in the lateral direction 720 (e.g., the y-direction) indicated by the arrow. In addition, the alignment direction of the LC molecules may be substantially homogeneous throughout the entire thickness of the birefringent Fresnel lens 704 without rotation. That is, the local oriented elements n of the LC molecules may be substantially constant laterally across the area of ​​the birefringent Fresnel lens 704 and perpendicularly across its thickness (e.g., the z-direction). The illustrated alignment may be suitable, for example, to provide polarization selectivity for linearly polarized light. In these embodiments, linearly polarized light having a polarization direction (e.g., the y-direction) parallel to the direction of LC alignment is n e or n o While one of these may be affected, linearly polarized light having a polarization direction perpendicular to the LC matching direction (e.g., the x-direction) is n e or n oThe other may be affected. As a result, the lens stack 700 imparts a refractive power of Δn / R for light with one linear polarization, as described above, while substantially zero refractive power for light with the other linear polarization.

[0163] In various embodiments of this specification, and throughout this specification, the birefringent Fresnel lens 704 may have a representative, local, mean, median, maximum, or minimum birefringence Δn of 0.05-0.10, 0.15-0.20, 0.20-0.25, 0.25-0.30, 0.30-0.35, 0.35-0.40, 0.40-0.45, 0.45-0.50, 0.50-0.55, 0.55-0.60, 0.60-0.65, 0.65-0.70, or any value within any range defined by any of these values, for example, 0.05-0.40. In addition, the birefringent Fresnel lens 704 can have an intralayer birefringence (Δn) range of 0.01-0.05, 0.05-0.10, 0.15-0.20, 0.20-0.25, 0.25-0.30, 0.30-0.35, 0.35-0.40, or any value within any range defined by any of these values.

[0164] In various embodiments of this specification, and throughout this specification, the birefringent Fresnel lens 704 has a thickness of approximately 0.1 μm to 200 μm, 0.1 to 5 μm, 5 to 50 μm, 50 to 100 μm, 100 to 150 μm, 150 to 200 μm, or any value within the range defined by these values, for example, 5 to 200 μm. Adaptive lens assembly, comprising a polarization-selective lens stack coupled with a switchable waveplate.

[0165] To provide images to multiple depth planes with high efficiency over a wide range of the visible spectrum, adaptive lens assemblies, according to various embodiments, include a polarization-selective lens stack (e.g., 600 in Figures 6A-6C, 700 in Figure 7B) comprising a birefringent lens and an isotropic lens. According to various embodiments, the adaptive lens assembly can be selectively switched between multiple states with different refractive powers. Hereinafter, an adaptive lens assembly is disclosed in which the selective switching is performed by activating or deactivating a switchable waveplate coupled to a polarization-selective lens contained within the adaptive lens assembly, according to an embodiment.

[0166] Referring to Figure 8A, in some embodiments, the adaptive lens assembly 800A is configured to be activated or deactivated by employing a switchable waveplate 804 that includes an LC in the same optical path as the polarization-selective lens stack 700 described above, comprising a birefringent Fresnel lens 704 and an isotropic lens 708. The Fresnel lens 704 may be formed using LC or other birefringent materials. The adaptive lens assembly 800A may be selectively switched between different states by electrically activating and deactivating the switchable waveplate 804 (or otherwise by changing the state of the waveplate, for example by applying different voltages). One embodiment of the switchable waveplate 804 is illustrated with respect to Figure 8B.

[0167] Referring to Figure 8B, in some embodiments, the switchable waveplate 802 may be a half-waveplate or polarizing rotor comprising a layer 802 of non-polymerized torsion nematic (TN) liquid crystal (LC), or a reactive mesogen (RM) comprising TN LC molecules configured to switch in response to the application of an electric field across the thickness of the TN LC layer 802. The TN LC layer 802 is placed between a pair of transparent substrates 812. Each transparent substrate 812 has conductive transparent electrodes 816, 820 formed on its inner surface. In some embodiments, the transparent electrodes 816, 820 may serve as substrates, and one or both of the substrates 812 may be omitted.

[0168] The surfaces of the transparent electrodes 816, 820 and / or the substrate 812 may be configured such that TN LC molecules in contact with or directly adjacent to the upper electrode 816 tend to be oriented with their long axes extending in a first lateral direction, while TN LC molecules in contact with or directly adjacent to the lower electrode 820 tend to be oriented with their long axes extending in a second lateral direction, which may intersect, for example, the first lateral direction at an angle of about 90 degrees. Thus, the TN LC molecules between electrodes 816 and 820 undergo torsion.

[0169] Referring again to Figure 8B (left), during operation, in the absence of an electric field traversing the TN LC layer 802 (deactivation state), the nematic orientors of the TN LC molecules undergo a smooth 90-degree twist across the thickness of the TN LC layer 802. As shown, incident light 808 polarized in a first direction (the same direction as the LC molecule closest to the lower electrode 812) is incident on the TN LC layer 802. The twisted arrangement of TN LC molecules within the TN LC layer 802 acts as an optical waveguide, rotating the plane of polarization by a quarter turn (90 degrees) before the light reaches the upper electrode 816. In this state, the TN LC layer 802 plays a role in shifting the polarization direction of linearly polarized light passing through it from one linear polarization direction to another. Therefore, the transmitted light 806A is polarized in a second direction (the same direction as the LC molecules adjacent to the upper electrode 816), which is opposite to the first direction.

[0170] On the other hand, when a voltage exceeding the threshold voltage (V>V) of the TN LC switchable waveplate 804 is applied across electrodes 816, 820 (right, activated state), the TN LC molecules in the TN LC layer 802 tend to match the resulting electric field, and the optical wave inductive properties of the TN LC layer 802, as described above for the deactivated state, are lost. In this state, the TN LC layer 802 plays a role in preserving the polarization direction of the light passing through it. Therefore, the incident light 808 and the transmitted light 806B are polarized in the same first direction (the same direction as the LC molecule closest to the lower electrode 820). When the electric field is turned off, the TN LC molecules relax to return to their twisted state, and the TN LC molecules of the TN LC layer 802 in the activated state return to the configuration of the TN LC molecules of the TN LC layer 802 in the deactivated state (left).

[0171] Still referring to Figure 8A, during operation, as described above, the polarization-selective lens stack 700 imparts a lens refractive force to the incident light 820 passing through it, depending on the polarization direction of the incident light 820. After the refractive force has been or has not been imparted thereto, depending on the relative polarization direction of the incident light, the light is incident on the switchable waveplate 804. As described above, the LC of the switchable waveplate 804 is configured such that when activated, for example electrically activated, the polarization of linearly polarized light passing through it is preserved, while when deactivated, for example electrically deactivated, the polarization of linearly polarized light passing through it is altered, for example, inverted or rotated. That is, a linearly perpendicularly polarized (LVP) light beam is converted to a linearly horizontally polarized (LHP) light beam, and vice versa, or the polarization is preserved depending on whether the switchable waveplate 804 is activated or deactivated.

[0172] During operation, the LC of the birefringent Fresnel lens 704 is configured such that when the polarization direction of linearly polarized incident light 820 is parallel to the optical axis of the birefringent Fresnel lens 704, the polarization-selective lens stack 700 imparts refractive power thereto, as described above with respect to Figure 6B; while when the polarization direction of linearly polarized incident light 820 is perpendicular to the optical axis, the polarization-selective lens stack 700 imparts substantially zero refractive power thereto, as described above with respect to Figure 6C. The polarization of linearly polarized light passing through the switchable waveplate 804 after passing through the birefringent lens stack 700 is preserved, while the polarization of linearly polarized light passing through the switchable waveplate 804 is reversed or rotated due to the rearrangement of the liquid crystal molecules when the stack is deactivated, for example, when the stack is deactivated.

[0173] With respect to Figures 8A-8B, an adaptive lens assembly is described, comprising a passive polarization-selective lens stack coupled to a waveplate (Figure 8A) for switchably imparting lens refractive power. The inventors recognize that by arranging multiple such elements, adaptive lens assemblies with multiple different lens refractive powers can be formed. Accordingly, embodiments of an adaptive waveplate lens assembly comprising multiple passive polarization-selective lens stacks coupled to a waveplate are disclosed below. Such an adaptive lens assembly may be integrated with a waveguide on either the user side or the world side to form a display device, for example, as described with respect to Figures 3A and 3B.

[0174] Figure 9A illustrates an embodiment of an adaptive lens assembly 900 comprising a plurality of passive polarization-selective lens stacks and a plurality of waveplates, which are arranged alternately to impart a plurality of refractive powers, for example, at least four possible, to the light passing through them. The adaptive lens assembly 900 comprises, in the order of light passing through it, a first switchable waveplate (HWP1) 804-1, e.g., a half-waveplate, a first polarization-selective lens stack (L1) 700-1, a second switchable waveplate (HWP2) 804-2, e.g., a half-waveplate, and a second polarization-selective lens stack (L2) 700-2. HWP1 804-1 and HWP2 804-2 are each configured in a manner similar to those described above with respect to Figures 8A and 8B. In addition, L1 700-1 and L2 700-2 are configured in a manner similar to those described above with respect to Figures 6A-6C, 7A-7B, and 8A-8B, respectively. However, the first and second polarization-selective lens stacks 700-1 and 700-2 have different optical axes, different curvatures (e.g., effective radius of curvature), and / or different birefringences. That is, L1 700-1 has a first optical axis (extending vertically or in the y-direction) and is configured to impart a first refractive force φ1 of Δn1 / R1 or substantially zero to light incident on it, having a polarization direction parallel or perpendicular to the optical axis, respectively, while 700-2 has a second optical axis (extending horizontally or in the x-axis) and is configured to impart a second refractive force φ2 of Δn2 / R2 or substantially zero to light incident on it, having a polarization direction parallel or perpendicular to the optical axis, respectively.

[0175] Figures 9B–9E illustrate the adaptive lens assembly 900 in operation with respect to incident light 820 having polarization parallel to the optical axis of L1 700-1 in four different states, corresponding to the states of HWP1 804-1 / HWP804-2 being deactivated (off) / deactivated (off) (Figure 9B), activated (ON) / activated (ON) (Figure 9C), off / on (Figure 9D), and on / off (Figure 9E). As described above, HWP1 804-1 and HWP2 804-2 can be turned off and on or deactivated and activated by removing and applying a voltage across the TN LC layer, respectively. HWP1 804-1 and HWP2 804-2 are configured, respectively, to alter the polarization state of light passing through them when electrically deactivated (off), for example, by rotating or reversing the polarization state, while configured, when activated (on), to substantially allow light to pass through them without altering the polarization state of the light passing through them. An electrical signal, such as a current signal or a voltage signal, for switching HWP1 804-1 and HWP2 804-2, respectively, may be provided by a switching circuit (not shown) electrically connected thereto. For illustrative purposes, both HWP1 804-1 and HWP2 804-2 are TN LC cells, respectively, having optical axis directions along the y and x directions in their two substrates, as in Figure 8B. In the illustrated embodiment, the incident light 820 has polarization parallel to the y direction, i.e., linear vertical polarization (LVP). However, it should be understood that the polarization axis of incident light 820 can be polarized in different directions to achieve different refractive power states, for example, linear horizontal polarization (LHP).

[0176] Referring to Figure 9B, HWP1 804-1 and HWP2 804-2 are each configured to rotate the polarization of linearly polarized light having one of LVP and LHP in the off state to linearly polarized light having the other of LVP and LHP. Thus, incident light 820 having LHP is converted into light 824 incident on L1 700-1 having LHP as it passes through HWP1 804-1, which imparts a substantially zero refractive power (φ1=0) due to the relative orthogonal orientation between the polarization of light 824 and the optical axis of L1 700-1. Subsequently, light 828 having LHP incident on HWP2 804-2 is converted into light 832 having LVP. L2 700-2 imparts virtually zero refractive power (φ2=0) due to the relative orthogonal orientation between the polarization of L2 700-2 and the optical axis of L2 700-2. In short, the adaptive lens assembly 900 imparts a net refractive power φ1+φ2 equal to approximately zero to the incident light 820 having LVP, without altering its polarization, thereby outputting light 836 having LVP.

[0177] Referring to Figure 9C, HWP1 804-1 and HWP2 804-2 are configured to be ON and store the polarization of linearly polarized light passing through them. Thus, the polarization of incident light 820, which has an LVP, is stored in light 824 incident on L1 700-1 as it passes through HWP1 804-1, which imparts a refractive power (φ1) due to the relative parallel orientation between the polarization of light 824 and the optical axis of L1 700-1. Subsequently, the polarization of light 828, which has an LVP and is incident on HWP2 802-2, is stored in light 832. L2 700-2 imparts a substantially zero refractive power (φ2=0) due to the relative orthogonal orientation between the polarization of light 832 and the optical axis of L2 700-2. In short, the adaptive lens assembly 900 imparts a net refractive power φ1 + φ2, equal to approximately φ1, to the incident light 820 having LVP, and outputs light 836 having LVP.

[0178] Referring to Figure 9D, HWP1 804-1 is configured in the off state to rotate the polarization of linearly polarized light having one of LVP and LHP to linearly polarized light having the other of LVP and LHP, while HWP2 804-2 is configured in the on state to store the polarization of linearly polarized light. Thus, incident light 820 having LVP is converted to light 824 having HVP as it passes through HWP1 804-1 and is incident on L1 700-1, which imparts a substantially zero refractive power (φ1=0) due to the relative orthogonal orientation between the polarization of light 824 and the optical axis of L1 700-1. Subsequently, the polarization of light 828 having HVP, which passes through HWP2 802-2, is stored in light 832. When light 832 is incident on L2 700-2, it has HVP, which imparts a refractive power (φ2) due to the relative parallel orientation between the polarization of light 832 and the optical axis of L2 700-2. In short, the adaptive lens assembly 900 imparts a net refractive power φ1 + φ2 equal to approximately φ2 to the incident light 820, which has LVP, and outputs light 836, which has LHP.

[0179] Referring to Figure 9E, HWP1 804-1 is configured in the ON state to store the polarization of linearly polarized light, while HWP2 804-2 is configured in the OFF state to rotate the polarization of linearly polarized light having one of LVP and LHP to linearly polarized light having the other of LVP and LHP. Thus, the polarization of incident light 820 having LVP is stored in light 824 incident on L1 700-1 having LVP as it passes through HWP1 804-1, which imparts a refractive force (φ1) due to the relative parallel orientation between the polarization of light 824 and the optical axis of L1 700-1. Subsequently, light 828 having LVP passing through HWP2 804-2 is converted to light 832 having HVP. L2 700-2 imparts a refractive power (φ2) due to the relative parallel orientation between the polarization of light 832 and the optical axis of L2 700-2. In short, the adaptive lens assembly 900 imparts a net refractive power φ1 + φ2 to the incident light 820 having LVP and outputs light 836 having LHP.

[0180] Therefore, as illustrated by Figures 9A-9E, four possible net refractive powers (0, φ1, φ2, and φ1+φ2) can be imparted to the light passing through the adaptive lens assembly 900 with respect to linearly polarized light. Using numerical examples, net refractive powers of 0, 0.75D, 1.5D, and 2.25D can be obtained using the adaptive lens assembly 900 with respect to φ1=0.75D and φ2=1.5D for the design wavelengths.

[0181] Referring still to Figures 9A-9E in conjunction with Figures 3A and 3B, in the illustrated embodiments, the incident light 820 may represent a light beam incident on either the world-side adaptive lens assembly 204 or the user-side adaptive lens assembly 208. By placing the adaptive lens assembly 900 on one side or both sides, the display system described above with respect to Figures 3A and 3B, for example, can be implemented according to various embodiments as described herein. A display device comprising an adaptive lens assembly having a polarization-selective lens stack coupled to a non-polarizing waveguide assembly.

[0182] In the following exemplary implementation, the adaptive lens assembly, comprising multiple switchable polarization-selective lens stacks (e.g., adaptive lens assembly 900, Figures 9A-9E), is integrated into a display device, such as the display device described above with respect to Figures 2, 3A, and 3B.

[0183] Figure 10 illustrates an exemplary display device 1000, which includes a waveguide assembly 1012 interposed between a first, i.e., a front adaptive lens assembly (FLA) 1004 and a second, i.e., a back adaptive lens assembly (BLA) 1008. Display device 1000 can be analogous to display devices 300A, 300B described above with respect to Figures 3A and 3B. In the illustrated embodiment, the BLA 1008 is configured similarly to the adaptive lens assembly 900 described above with respect to Figures 9A-9E and includes a first switchable waveplate (HWP1) 804-1, a first polarization-selective lens stack (L1) 700-1, a second switchable waveplate (HWP2) 804-2, and a second polarization-selective lens stack (L2) 700-2. The first and second polarization-selective lens stacks 700-1 and 700-2 have different, e.g., orthogonal optical axis, curvature (e.g., effective radius of curvature), and / or different birefringences, such that L1 700-1 is configured to impart a first refractive force φ1 of n1 / R1 or substantially zero with respect to light incident thereon having a polarization direction parallel or perpendicular to the optical axis, respectively, while L2 700-2 is configured to impart a second refractive force φ2 of n2 / R2 or substantially zero with respect to light incident thereon having a polarization direction parallel or perpendicular to the optical axis, respectively.

[0184] FLA1004 includes a third switchable waveplate (HWP3) 804-3, a third polarization-selective lens stack (L3) 700-3, a fourth switchable waveplate (HWP4) 804-4, and a fourth polarization-selective lens stack (L4) 700-4. The third and fourth polarization-selective lens stacks 700-3 and 700-4 have different, e.g., orthogonal optical axes, effective radius of curvature, and / or different birefringences, such that L3 700-3 is configured to impart a third refractive power φ3 of n3 / R3 or substantially zero to light incident on it having a polarization direction parallel or perpendicular to the optical axis, respectively, while L4 700-4 is configured to impart a fourth refractive power φ4 of n4 / R4 or substantially zero to light incident on it having a polarization direction parallel or perpendicular to the optical axis, respectively.

[0185] In various embodiments, the effective radii of curvature of L1 700-1 and L2 700-2 are such that φ1 and φ2 have a first sign, for example, a positive sign, while the effective radii of curvature of L3 700-3 and L4 700-4 are such that φ3 and φ4 have a second sign opposite to the first sign, for example, a negative sign. That is, when the non-zero net refractive powers (φ1, φ2, and φ1+φ2) that can be considered as three possibilities for FLA1004 may have one of the convergent or divergent effects (e.g., convergent), the non-zero net refractive powers (φ3, φ4, and φ3+φ4) that can be considered as three possibilities for BLA1008 may have the other of the convergent or divergent effects (e.g., divergent). In the illustrated embodiment, FLA1004 and BLA1008 are configured to be substantially identical except for the curvature of the interface between the birefringent lens and the isotropic lens (for example, one is concave and the other is convex, or vice versa). In particular, FLA1004 and BLA1008 form mirror images of each other around the waveguide assembly 1012. Thus, as configured, L1 804-1 and L3 804-3 have refractive powers φ1 and φ3, respectively, which are substantially the same in magnitude but opposite in sign, and L2 804-2 and L4 804-4 have refractive powers φ2 and φ4, respectively, which are substantially the same in magnitude but opposite in sign. That is, φ1 is approximately equal to -φ3, and φ2 is approximately equal to -φ4.

[0186] Still referring to Figure 10, in the illustrated embodiment, the waveguide assembly 1012 is configured to externally couple unpolarized light that is fully internally reflected. In this configuration, the display device 1000 also includes a linear polarizer 1005 between the waveguide assembly 1012 and the BLA 1008, configured to reduce or eliminate, for example, reflect or absorb, light having a polarization state that does not lead to lensing by the BLA 1008. For example, in an array where the externally coupled light 1009 from the waveguide assembly 1012, or light 1020 transmitted unaffected through the FLA 1004, is not linearly polarized, for example, not LVP, the linear polarizer 1005 plays the role of linearly polarizing the transmitted light and sending the incident light 820 into the BLA 1008.

[0187] As configured, BLA1008 provides variable refractive power (φ1, φ2, and φ1+φ2) and plays a role in shaping the image into multiple depth planes for the virtual image emitted from the waveguide assembly 1012 toward the user's eye. BLA1008 provides the virtual image by focusing the image from the waveguide assembly 1012 toward multiple depth planes, but the world image may be distorted by BLA1008. FLA1004 plays a role in compensating for the distortion of the world image caused by BLA1008 by providing variable refractive power (φ3=-φ1, φ4=-φ2, and φ3+φ4=-(φ1+φ2)) so that the world image is presented to the user's eye without substantial distortion.

[0188] In various embodiments, for example, when deactivated, FLA1004 and BLA1008 may provide net refractive power (positive or negative) within the ranges of approximately ±5.0 diopters to 0 diopters, ±4.0 diopters to 0 diopters, ±3.0 diopters to 0 diopters, ±2.0 diopters to 0 diopters, and ±1.0 diopters to 0 diopters (including any range defined by any of these values, e.g., ±1.5 diopters). In some embodiments, FLA1004 between waveguide assembly 1012 and the world may have a positive refractive power, while BLA1008 between waveguide assembly 1012 and the user may have a negative refractive power, so that the refractive powers of FLA1004 and BLA1008 compensate for each other when viewing the world.

[0189] As described above, as the image of a virtual object produced by light externally coupled by the waveguide assembly 1012 moves in 3D, the net refractive power of the BLA 1008 on the user side is adjusted to conform to the changing depth of the virtual depth plane. At the same time, according to the embodiment, the net refractive power of the FLA 1004 is also adjusted in correspondence using a switching circuit so that the real-world view does not become undesirably out of focus or distorted. To address this and other needs, in some embodiments the display device 1000 includes a controller (not shown) configured such that when the net refractive power of one of the FLA 1004 and BLA 1008 is electrically adjusted, the net refractive power of the other FLA 1004 and BLA 1008 is adjusted in correspondence, and the combined net refractive power remains approximately constant, for example, approximately zero. The controller network and switchable waveplates are configured such that the time required to switch between HWPI804-1, HWP2 804-2, HWP3 804-3, and HWP4 804-4, adjust the virtual depth plane using user-side adaptive lens assembly 1008, and compensate for the real-world view using user-side adaptive lens assembly 1004 is less than approximately 100 milliseconds, less than approximately 50 milliseconds, less than approximately 10 milliseconds, less than approximately 5 milliseconds, less than approximately 10 milliseconds, less than approximately 10 milliseconds, less than approximately 5 milliseconds, less than approximately 1 millisecond, or within the range defined by any of these values. A display device including an adaptive lens assembly having a polarization-selective lens stack coupled to a polarization waveguide assembly.

[0190] Figure 11A illustrates exemplary display devices 1100 according to several embodiments. Similar to the display devices described above with respect to Figure 10, the display device 1100 includes a second adaptive lens assembly (BLA) 1008 which includes a first switchable waveplate (HWP1) 804-1, a first polarization-selective lens stack (L1) 700-1, a second switchable waveplate (HWP2) 804-2, and a second polarization-selective lens stack (L2) 700-2. However, unlike the display devices described above with respect to Figure 10, the display device 1100 includes a polarization waveguide assembly 1112 which externally couples polarization 1108, for example, circularly polarized light, into the BLA 1008. Therefore, BLA1008 also includes a first quarter-wave plate (QWP1) 1104, such as an achromatic quarter-wave plate, configured to convert the RHCP light 1108-R and LHCP light 1108-L externally coupled from the polarization waveguide assembly 1112 into linearly polarized light 820 incident on BLA1008. Thus, BLA1008 operates in a manner similar to that described above with respect to Figure 10.

[0191] However, unlike the display device 1000 in Figure 10, the display device 1100 does not have an FLA 1004, which is configured to compensate for or cancel out undesirable refractive power imparted to the world side light 1020 by the BLA 1008 when the BLA 1008 imparts refractive power to the light from the polarizing waveguide assembly 1112 containing virtual image information. Instead, the display device 1100 is configured to alternately display the world image and the virtual image. This is achieved by replacing the FLA 1004 (Figure 10) with a combination of the shutter 1120, the linear polarizer 1116, and the second quarter-wave plate (QWP2) 1114, for example, an achromatic quarter-wave plate. The polarizing waveguide assembly 1112 is described below with respect to Figure 11B, followed by the operating principle of the display device 1100 with respect to Figures 11C and 11D.

[0192] Figure 11B illustrates an embodiment of a polarizing waveguide assembly 1112 according to an embodiment. In some embodiments, the polarizing waveguide assembly 1112 is configured to output circularly polarized light, for example, circularly polarized light to right-hand circular polarization (RHCP) or left-hand circular polarization (LHCP). In various embodiments, the polarizing waveguide assembly 1112 may comprise a cholesteric liquid crystal (CLC) layer and / or a CLC grid (CLCG), which comprises liquid crystals arranged to have a plurality of chiral structures. Each chiral structure comprises a plurality of liquid crystal molecules that extend in the layer depth direction by at least a helical pitch and are continuously rotated in the rotational direction. The CLC layer or CLCG can be advantageously configured to substantially Bragg reflect elliptical or circularly polarized light having polarization palmarity that matches the rotational direction of the liquid crystal molecules, while substantially transmitting elliptical or circularly polarized light having polarization palmarity opposite to the rotational direction of the liquid crystal molecules. Based on these properties of CLC layers and CLCGs, various embodiments of display devices disclosed herein have a polarizing waveguide assembly 1112 comprising one or more CLC layers or CLCGs. According to embodiments, the polarizing waveguide assembly 1112 may also include a CLCG 1150 configured as an external coupling optical element such as an exit pupil expander (EPE). The polarizing waveguide assembly 1112 comprises a waveguide 1104 coupled to the CLCG 1150 and configured to propagate light by total internal reflection (TIR).

[0193] Referring still to Figure 11B, the liquid crystal molecules in the illustrated CLCG1150 are continuously rotated in the rotational direction, and the arrangement of the chiral liquid crystal molecules fluctuates periodically in the lateral direction (x, y direction) perpendicular to the layer depth direction (z direction). Due to the rotational arrangement of the liquid crystal molecules, when light 2604 is elliptical / circularly polarized light having polarization palmarity, for example, left-palmar or right-palmar, which matches the direction of rotation of the chiral liquid crystal molecules, light 2604 is Bragg reflected by CLCG1150. That is, the rotational arrangement of the liquid crystal molecules in CLCG1150 is such that CLCG1150 selectively Bragg reflects light with a certain palmarity, while non-Bragg reflecting or transmitting light with the opposite palmarity. In addition, since Bragg reflection occurs under diffraction conditions, the Bragg-reflected light 1108 is unidirectional (for example, most of the light is directed in one direction, such as the direction indicated by arrow 1108 in Figure 11B, when externally coupled). The externally coupled light can preserve a uniform polarization state, which corresponds to the chirality of the CLC material. Therefore, when configured as an optical external coupling element, the CLCG 1150 acts as both a polarizer and a unidirectional reflector, enabling efficient integration with other optical components within the display device 1100.

[0194] As described above, the display device 1100 is configured to alternately display a world image (Figure 11C) and a virtual image (Figure 11D). Referring to Figure 11C, when displaying the world image, the display device 1100 has configuration 1100C, in which both the shutter 1120 and the waveguide assembly 1112 are in the off state. In addition, both HWP-1 820-1 and HWP-2 820-2 are in the on and off states, respectively. As configured, the BLA 1008 is configured similarly to state 900B described above with respect to Figure 9B. Under this configuration, unpolarized light 1020 from the world is essentially unaffected, transmitted through the shutter 1120, and linearly polarized into light 1124 by the linear polarizer 1116, for example, linearly polarized horizontally (LHP). Light 1124 is converted to circularly polarized light 1108-L, e.g., LHCP light, which is incident on the polarization waveguide assembly 1112. Light 1108-L passes through the polarization waveguide assembly 1112 in the off state essentially unaffected and is converted by QWP1 1104 to linearly polarized light 820-2, e.g., LHP. BLA1008 is configured to impart substantially zero refractive power, as described above with respect to Figure 9B, thereby allowing light 820-2 to pass through essentially unaffected as seen by the eye.

[0195] Referring to Figure 11D, when displaying a virtual image, the display device has configuration 1100D in which both the shutter 1120 and the waveguide assembly 1112 are turned on. Thus, any light 1020 from the world side is blocked, for example, reflected. Thus, the display device configuration 1100D is substantially configured to display only virtual content externally coupled from the polarization waveguide assembly 1112, as described above with respect to Figure 11B. Light 1108-R, having circular polarization, e.g., RHCP, is incident on the QWP2 1104, and BLA 1008 is configured similarly to one of states 900C-900E described above with respect to Figures 9C-9E. Under this configuration, the circularly polarized light 1108-R is converted by the QWP2 1104 to linearly polarized light 820-1 having a polarization direction, e.g., perpendicular polarization direction (LVP). BLA1008 then applies refractive force according to one of the states 900C-900E described above with respect to Figures 9C-9E.

[0196] As described, the display device 1100 is configured to sequentially display a world image and a virtual image. To display both the world image and the virtual image to the user as if they were presented simultaneously, configurations 1100C (Figure 11C) and 1100D (Figure 11D) are time-multiplexed with respect to each other at a suitable frequency so that the human eye perceives them as essentially simultaneous. For example, shutters 1120 and HWP-1 820-1 and HWP-2 820-2 are alternated at a frequency at least twice the video refresh rate to minimize any switching artifacts. Advantageously, the display device 1100 can reduce the overall number of optical elements by replacing the FLA 1008 in the display device 1000. To compensate for the reduction in the intensity of the virtual image due to multiplexing and polarization, the intensity of the externally coupled light 1108-R can therefore be adjusted according to the embodiment. Display device including world-side and / or user-side shutter elements and user-side lens assembly

[0197] Figure 12A illustrates an embodiment of a display device 1200 having a single adaptive lens assembly 1208 on the user side of the eyepiece 1212 (the side of the eyepiece 1212 closest to the user's eye), according to some embodiments of the present disclosure. The lens assembly 1208 may include a variable focus element (VFE) assembly and may be configured to apply a positive, negative, or zero refractive force to the light passing through it. The display device 1200 may include one or more world-side shutter elements 1204 coupled to the world side of the eyepiece 1212 (the side of the eyepiece 1212 furthest from the user's eye and closest to world objects), and one or more user-side shutter elements 1202 coupled to the user side of the eyepiece 1212. Subsequently, by electrically activating the world-side shutter element 1204 and the user-side shutter element 1202 as described herein, world light 432 may pass through the display device 1200 with zero net refractive power applied by the lens assembly 1208, and virtual image light 423 may pass through it with a non-zero (e.g., negative) net refractive power applied by the lens assembly 1208.

[0198] In the illustrated embodiment, the world-side shutter element 1204 includes a world-side polarizer 1216 and a world-side switchable waveplate 1220. The world-side polarizer 1216 may be positioned closer to the world object 430 so that the world light 432 first passes through the world-side polarizer 1216 before passing through the world-side switchable waveplate 1220. In response to passing through the world-side polarizer 1216, the world light 432 is linearly polarized along a first axis. Thus, the world-side polarizer 1216 may comprise a linear polarizer. After passing through the world-side polarizer 1216, the world light 432 passes through the world-side switchable waveplate 1220. When electrically activated, the world-side switchable waveplate 1220 rotates the polarization of the world light 432 by 90 degrees, for example, so that LVP light is converted to LHP light, or LHP light is converted to LVP light. If not electrically activated, the world-side switchable waveplate 1220 leaves the world light 432 substantially unchanged.

[0199] In the illustrated embodiment, the user-side shutter element 1202 includes a user-side polarizer 1214 and a user-side switchable waveplate 1218. The user-side polarizer 1214 may be positioned closer to the eyepiece 1212 and the world object 430 so that the virtual image light 423 and the world light 432 first pass through the user-side polarizer 1214 before passing through the user-side switchable waveplate 1218. In response to passing through the user-side polarizer 1214, the virtual image light 423 and the world light 432 are linearly polarized along a second axis perpendicular to a first axis. Thus, the user-side polarizer 1214 may comprise a linear polarizer perpendicular to the world-side polarizer. After passing through the user-side polarizer 1214, the virtual image light 423 and the world light 432 pass through the first layer of the lens assembly 1208. As described herein, the first layer of the lens assembly 1208 can apply refractive power to the light passing through it. After passing through the first layer of the lens assembly 1208, the virtual image light 423 and the world light 432 pass through the user-switchable waveplate 1214. When electrically activated, the user-switchable waveplate 1214 rotates the polarization of the virtual image light 423 and the world light 432 by 90 degrees, for example, converting LVP light to LHP light, or LHP light to LVP light. When not electrically activated, the user-switchable waveplate 1214 leaves the virtual image light 423 and the world light 432 substantially unchanged.

[0200] After passing through the user-switchable waveplate 1218, the virtual image light 423 and the world light 432 pass through a second layer of the lens assembly 1208. As described herein, the second layer of the lens assembly 1208 may apply a refractive power to the light passing through it so as to cancel out or add to the refractive power applied to the light when it passes through the first layer. For example, the first and second layers of the lens assembly 1208 may be configured such that when the user-switchable waveplate 1218 is electrically activated, the light passing through both layers is applied a non-zero net refractive power, and when the user-switchable waveplate 1218 is not electrically activated, the light passing through both layers is applied a zero net refractive power, i.e., no net refractive power. Therefore, the first and second layers of the lens assembly 1208 may be configured to apply a positive refractive power to light having a first linear polarization and a negative refractive power (of equal magnitude) to light having a second linear polarization orthogonal to the first linear polarization.

[0201] In some embodiments, the first and second layers of the lens assembly 1208 are diffraction waveplate lenses. In some embodiments, the lens assembly 1208 may take the form of different types of VFEs, such as LC Fresnel lenses, deformable lenses, or equivalents. In some embodiments, one or more components of the user-side shutter element 1202 are considered subcomponents of the lens assembly 1208 (i.e., considered to be contained within the lens assembly 1208). In one embodiment, the user-side polarizer 1214 is considered a subcomponent of the lens assembly 1208. In another embodiment, the user-side switchable waveplate 1218 is considered a subcomponent of the lens assembly 1208. In yet another embodiment, both the user-side polarizer 1214 and the user-side switchable waveplate 1218 are considered subcomponents of the lens assembly 1208. Exemplary VFEs and other adaptive lens components that may be implemented as part of one or more of the lens assemblies described herein are U.S. Patent Application No. 15 / 902,927, filed on 22 February 2018 and published on 23 August 2018 as U.S. Patent Publication No. 2018 / 0239177, and U.S. Patent Application No. 2018 / 0239147, filed on 22 February 2018 and published on 23 August 2018. As described in U.S. Patent Application No. 15 / 902,814, filed on 22 March 2018 and published on 27 September 2018 as U.S. Patent Publication No. 2018 / 0275394, and U.S. Patent Application No. 16 / 006,080, filed on 12 June 2018 and published on 13 December 2018 as U.S. Patent Publication No. 2018 / 0356639 (all of which are expressly incorporated herein by reference as a whole).Additional embodiments of such components are provided in U.S. Provisional Patent Application No. 62 / 639,882 (Patent Attorney No. MLEAP.180PR), filed on 7 March 2018, and U.S. Patent Application No. 16 / 158,041 (Patent Attorney No. MLEAP.183A), filed on 11 October 2018 (both of which are also expressly incorporated herein by reference as a whole).

[0202] Figure 12B illustrates an embodiment of the display device 1200 operating according to a first state, according to some embodiments of the present disclosure. While operating according to the first state, the projector and input optics 1222 are turned off, the world-side switchable waveplate 1220 is electrically activated, and the user-side switchable waveplate 1218 is not electrically activated. The world light 432 is first linearly polarized along a first axis by the world-side polarizer 1216. The polarization of the world light 432 is then rotated by 90 degrees by the world-side switchable waveplate 1220. The world light 432 is then linearly polarized along a second axis perpendicular to the first axis by the user-side polarizer 1214. The first layer of the lens assembly 1208 then applies a first refractive force to the world light 432. The world light 432 then passes through the user-side switchable waveplate 1218 substantially unchanged. Subsequently, the second layer of the lens assembly 1208 applies a second refractive force to the world light 432 that is equal in magnitude to the first refractive force but has the opposite sign, thereby canceling out the first refractive force. The world light 432 then reaches the user's eye.

[0203] Figure 12C illustrates an embodiment of the display device 1200 operating according to a second state, according to some embodiments of the present disclosure. While operating according to the second state, the projector and input optics 1222 are turned on, the world-side switchable waveplate 1220 is not electrically activated, and the user-side switchable waveplate 1218 is electrically activated. World light 432, upon impact with the world-side polarizer 1216, is linearly polarized by the world-side polarizer 1216 along a first axis. The world light 432 then passes through the world-side switchable waveplate 1220 substantially unchanged. The world light 432 is then linearly polarized by the user-side polarizer 1214 along a second axis perpendicular to the first axis, reducing, blocking, or dimming the world light 432 completely or at least partially. In parallel, the virtual image light 423 is projected onto one or more waveguides of the eyepiece 1212 by the projector and input optics 1222. The virtual image light 423 is then externally coupled by the eyepiece 1212. The virtual image light 423 is then linearly polarized along a second axis by the user-side polarizer 1214. The first layer of the lens assembly 1208 then applies a first refractive force to the virtual image light 423. The polarization of the virtual image light 423 is then rotated by 90 degrees by the user-side switchable waveplate 1218. The second layer of the lens assembly 1208 then applies a second refractive force to the virtual image light 423 that is equal in magnitude and has the same sign as the first refractive force, thereby doubling the applied refractive force. The virtual image light 423 then reaches the user's eye.

[0204] Figure 13 illustrates a method 1300 for operating an optical system according to some embodiments of the present disclosure. One or more steps of method 1300 may be performed in a different order than in the illustrated embodiments, and one or more steps of method 1300 may be omitted during the implementation of method 1300. In some embodiments, one or more steps of method 1300 may be implemented as a computer-readable medium or computer program product comprising instructions that, when executed by one or more computers, cause one or more computers to perform at least partially some or all of the steps of method 1300. Such a computer program product may be transmitted over a wired or wireless network in a data carrier signal carrying the computer program product.

[0205] In step 1302, the light associated with the world object is received by the optical system. In step 1304, the light associated with the world object is linearly polarized along the first axis. In step 1306, it is determined whether the optical system is operating according to the first or second state. If the optical system is operating according to the first state, method 1300 proceeds to step 1308. If the optical system is operating according to the second state, method 1300 proceeds to step 1314. In step 1308, the polarization of the light associated with the world object is rotated by 90 degrees. In step 1310, the light associated with the world object is linearly polarized along the second axis perpendicular to the first axis. In step 1312, a zero net refractive power is applied to the light associated with the world object. The light associated with the world object then reaches the user's eye.

[0206] In step 1314, the light associated with the virtual image is projected onto the eyepiece of the optical system. In step 1316, the light associated with the virtual image is externally coupled by the eyepiece. In step 1318, the light associated with the world object and the light associated with the virtual image are linearly polarized along a second axis. In step 1320, the polarization of the light associated with the virtual image is rotated by 90 degrees. In step 1322, a non-zero net refractive power is applied to the light associated with the virtual image. The light associated with the virtual image then reaches the user's eye.

[0207] Figure 14 illustrates a method 1400 for operating an optical system according to several embodiments of the present disclosure. One or more steps of method 1400 may be performed in a different order than in the illustrated embodiments, and one or more steps of method 1400 may be omitted during implementation of method 1400. One or more steps of method 1400 may be combined with one or more steps of method 1300. In step 1402, ambient light is detected by an ambient light sensor. In step 1404, the shutter frequency is determined based on the detected ambient light. In step 1406, the optical system is made to switch between operation according to a first state and operation according to a second state based on the shutter frequency.

[0208] Figure 15 illustrates exemplary embodiments of Method 1400 according to several embodiments of the present disclosure. The upper plot of Figure 15 shows the detected ambient light intensity as a function of time (e.g., as detected by ambient light sensors 434, 534). The lower plot of Figure 15 shows the state switching between the first and second states as a function of time, with the time aligned with the upper plot. At time T1, the user of the optical system is in a shaded outdoor area, and the detected ambient light has a moderate intensity. Based on the detected ambient light at time T1, a first shutter frequency is determined. The step of determining the shutter frequency may include determining a first period P1, which is the duration during which the optical system operates according to the first state prior to switching to the second state, and a second period P2, which is the duration during which the optical system operates according to the second state prior to switching to the first state. Alternatively, or in addition, the step of determining the shutter frequency may include, among other possibilities, determining the ratio P1 / P2. Between times T1 and T2, the optical system is made to switch between a first state and a second state based on a first shutter frequency.

[0209] At time T2, the user of the optical system is repositioned in a low-light indoor area, and the detected ambient light has low intensity. Based on the detected ambient light at time T2, the second shutter frequency is determined to have a higher ratio P1 / P2 than the first shutter frequency. In other words, to improve the user experience and avoid excessive dimming of world light under low-light conditions, the shutter frequency may be adjusted to increase the amount of time that world light is allowed to pass through the optical system. Between times T2 and T3, the optical system is made to switch between the first and second states based on the second shutter frequency.

[0210] At time T3, the user of the optical system is repositioned in an outdoor area with direct sunlight, and the detected ambient light is of high intensity. Based on the detected ambient light at time T3, the third shutter frequency is determined to have a lower ratio P1 / P2 than both the first and second shutter frequencies. In other words, to improve the user experience and reduce world light under high-light conditions, the shutter frequency may be adjusted to reduce the amount of time that world light is allowed to pass through the optical system. After time T3, the optical system is switched between the first and second states based on the third shutter frequency.

[0211] Figure 16A illustrates an embodiment of the display device 1600 operating according to a first state, according to several embodiments of the present disclosure. The display device 1600 may include one or more components that are functionally equivalent or similar to one or more of those described above with reference to Figures 4A-4C, 5, 11A-11D, and / or 12A-12C. For example, the display device 1600 may have a single adaptive lens assembly 1605 on the user side of the eyepiece 1602 (the side of the eyepiece 1602 closest to the user's eye). The lens assembly 1605 may include a VFE assembly and may be configured to apply a positive, negative, or zero refractive force to the light passing through it. The display device 1600 may include a shutter element 1603 coupled to the world side of the eyepiece 1602 (the side of the eyepiece 1602 furthest from the user's eye and closest to world objects). While operating according to the first state, the controller 1620 turns off the projector 1614, deactivates the lens assembly 1605, and opens the shutter element 1603. When the shutter element 1603 is opened (i.e., electrically activated), the world light 432 passing through it remains substantially unchanged. When the lens assembly 1605 is inactive, it imparts zero net refractive power to the light (e.g., world light 432) passing through it. Thus, while operating according to the first state, the world light 432 can be presented to the user substantially unchanged. In some embodiments, as will be described in more detail below, the display device 1600 may maintain / continue the first state for an extended period of time (e.g., indefinitely, or until the display device 1600 is requested to present virtual content to the user).

[0212] Figure 16B illustrates an embodiment of the display device 1600 operating according to a second state, according to some embodiments of the present disclosure. While operating according to the second state, the controller 1620 turns on the projector 1614, activates the lens assembly 1605, and closes the shutter element 1603. When the shutter element 1603 is closed (i.e., not electrically activated), the world light 432 passing through it is substantially blocked. When the projector 1614 is turned on, the virtual image light 423 is projected onto the eyepiece 1602 and then externally coupled to the user's eye by the eyepiece 1602. When the lens assembly 1605 is active, the lens assembly 1605 imparts a non-zero net refractive power to the light passing through it (e.g., the virtual image light 423). Therefore, while operating according to the second state, the display device 1600 may present the user with virtual content that is perceived by the user as being positioned at one or more of the various possible depths. In some embodiments, as will be described in more detail below, the display device 1600 may hold / maintain the second state for an extended period of time (e.g., indefinitely, or until the display device 1600 is requested to provide the user with a view of the environment). In some embodiments, the display device 1600 may synchronously control the shutter element 1603 and the lens assembly 1605 to rapidly alternate between the first and second states at a specific rate or frequency.

[0213] Figure 16C illustrates an embodiment of the display device 1600 operating according to a third state, according to some embodiments of the present disclosure. While operating according to the third state, the controller 1620 turns on the projector 1614, deactivates the lens assembly 1605, and opens the shutter element 1603. When the shutter element 1603 is opened (i.e., electrically activated), the world light 432 passing through it remains substantially unchanged. When the projector 1614 is turned on, the virtual image light 423 is projected onto the eyepiece 1602 and then externally coupled to the user's eye by the eyepiece 1602. When the lens assembly 1605 is inactive, the lens assembly 1605 imparts zero net refractive power to the light passing through it (e.g., world light 432 and / or virtual image light 423). Therefore, while operating according to the third state, the display device 1600 may present the user with virtual content that is perceived by the user as being located at optical infinity.

[0214] Therefore, in the third state, the display device 1600 does not need to activate the lens assembly 1605 while it is directing light representing the virtual content at optical infinity into the eyepiece 1602, thus allowing light from the real world to pass towards the user without any problems. In some embodiments, as will be described in more detail below, the display device 1600 may hold / maintain the third state for an extended period of time (e.g., infinity, or until the display device 1600 is requested to present the virtual content below optical infinity). In some embodiments, the display device 1600 may synchronously control the shutter element 1603 and the lens assembly 1605 to rapidly alternate between the second and third states so as to rapidly present some virtual content below optical infinity and other virtual content at optical infinity. As described with reference to Figures 14 and 15, the shutter frequency for switching between the first, second, and / or third states may be determined based on the detected ambient light and / or the desired brightness of the virtual content.

[0215] As described above, in some embodiments, the display device 1600 does not have to control the shutter element 1603 and lens assembly 1605 synchronously to rapidly alternate between two or more states, but instead may selectively hold / maintain a single state (e.g., one of a first state, a second state, and a third state), or otherwise independently control the shutter element 1603 and lens assembly 1605 over a long period of time. In at least some of these embodiments, the display device 1600 may be configured to alternate between at least two different operating modes, including (i) a first operating mode in which the display device 1600 is configured to control the state of the shutter element 1603 and the state of the lens assembly 1605 independently or otherwise asynchronously, and (ii) a second operating mode in which the display device 1600 is configured to control the state of the shutter element 1603 and the state of the lens assembly 1605 synchronously. For example, in a first operating mode, the display device 1600 may hold / maintain a single state (e.g., one of a first state, a second state, and a third state), or otherwise control the shutter element 1603 and the lens assembly 1605 independently; in a second operating mode, the display device 1600 may synchronously switch between two or more states (e.g., two or more of a first state, a second state, and a third state).

[0216] In some embodiments, in the first operating mode, the display device 1600 may maintain a state similar to or equivalent to the second state for an extended period of time (e.g., indefinitely, or until the display device 1600 is requested to provide the user with a view of the environment). In at least some such embodiments, the first operating mode may correspond to a VR mode in which the controller 1620 turns on the projector 1614, optionally activates the lens assembly 1605, closes the shutter element 1603, or otherwise maintains a relatively dark state. Optionally, in the first operating mode, the controller 1620 may cause the lens assembly 1605 to switch states as needed, imparting an appropriate amount of refractive power to the light from the projector. In the embodiments described above, the controller 1620 may cause the display device 1600 to switch between and / or exit a first operating mode based on any of a variety of factors, including user input (as indicated by data received from one or more sensors, a user interface, an input device, etc.), an application launched on the display device 1600, user preferences, sensor data, and the equivalent. For example, the controller 1620 may switch to a first operating mode to initiate a VR experience that provides little to no see-through visibility of the environment in front of it, in response to the user launching or terminating the execution of a specific application on the display device 1600, receiving an indication that the user desires to switch to such a mode or exit another mode based on input received through a handheld controller and / or a graphical user interface, and / or the occurrence of one or more other events.Similarly, the controller 1620 may terminate the VR experience or terminate the first operating mode so that the user transitions to an AR or mixed reality (MR) experience, which is provided with increased see-through visibility of the environment in front of it, based on the launch or termination of a specific application on the display device 1600, the reception of an indication that the user desires to exit VR mode or transition to another mode (e.g., AR or MR mode), and / or the occurrence of one or more other events. Other configurations are also possible.

[0217] In other embodiments, in the first operating mode, the display device 1600 may maintain a state similar to or equivalent to the third state for an extended period of time (e.g., indefinitely, or until the display device 1600 is required to present the virtual content below optical infinity). In at least some such embodiments, the first operating mode may correspond to a mode in which the controller 1620 causes the projector 1614 to turn on, the lens assembly 1605 to hold in a fixed state, and the shutter element 1603 to be open and held. Optionally, in the first operating mode, the controller 1620 may cause the shutter element 1603 to switch between an open and closed state. In the embodiments described above, the controller 1620 may cause the display device 1600 to switch to and / or exit the first operating mode based on any of a variety of factors, including the depth at which the user's eyes are determined to be fixed, the depth in front of the user where the virtual content will be perceived by the user, the accommodative-convergence-divergence motion mismatch with respect to the virtual content, and equivalents. In some embodiments, the controller 1620 may utilize data from one or more inward-facing cameras (e.g., images of one or both of the user's eyes) to determine the depth at which the user's eyes are fixed, evaluate the determined depth against a set of criteria, and, based on the evaluation, switch to transitioning to and / or exiting the first operating mode. For example, in these embodiments, the controller 1620 may, at least partially, determine, based on the depth at which the user's eyes are determined to be fixed, whether the near-accommodative-convergence-divergence motion mismatch with respect to the virtual content exceeds one or more predetermined thresholds, and in response to the determination that the near-accommodative-convergence-divergence motion mismatch with respect to the virtual content exceeds one or more predetermined thresholds, switch to transitioning to and / or exiting the first operating mode.Exemplary systems and techniques for modulating the wavefront divergence of light representing virtual content for improved user perception, comfort, and / or experience, which may be implemented as part of or representing one or more of the systems and techniques described herein, include U.S. Patent Application No. 15 / 430,277, filed on 10 February 2017 and published on 17 August 2017 as U.S. Patent Publication No. 2017 / 0237974, and U.S. Patent Application No. 15 / 469,369, filed on 24 March 2017 and published on 28 September 2019 as U.S. Patent Publication No. 2017 / 0276948. As described in U.S. Patent Application No. 16 / 250,931, filed on 17 January 9 and published on 8 August 2019 as U.S. Patent Publication No. 2019 / 0243448; U.S. Patent Application No. 16 / 353,989, filed on 14 March 2019 and published on 10 October 2019 as U.S. Patent Publication No. 2019 / 0311527; and U.S. Patent Application No. 16 / 389,529, filed on 19 April 2019 and published on 24 October 2019 as U.S. Patent Publication No. 2019 / 0324276 (all of which are expressly incorporated herein by reference as a whole). In some embodiments, one or more of the systems and techniques described in one or more of the aforementioned patent applications may represent, or be implemented as part of, one or more systems and techniques for switching the transition to and / or termination of a first operating mode. Other configurations are also possible.

[0218] In the second operating mode, the controller 1620 of the display device 1600 may synchronously switch the shutter element 1603 and the lens assembly 1605 between different states in such a manner that an inverse relationship is created between the amount of ambient light from the user's environment that is allowed to pass through the shutter assembly 1603 toward the user and the amount of wavefront divergence imparted to the light that passes through the lens assembly 1605 toward the user. For example, in the second operating mode, the controller 1620 of the display device 1600 may synchronously switch the shutter element 1603 and the lens assembly 1605 between two states similar or equivalent to the first and second states as described above with reference to Figures 16A and 16B, respectively, or between two states similar or equivalent to the second and third states as described above with reference to Figures 16B and 16C, respectively.

[0219] Figure 17 illustrates a simplified computer system 1700 according to embodiments described herein. The computer system 1700 as illustrated in Figure 17 may be incorporated into devices as described herein. Figure 17 provides a schematic illustration of one embodiment of the computer system 1700 that can carry out some or all of the steps of the method provided by various embodiments. It should be noted that Figure 17 is intended solely to provide a generalized illustration of various components, any or all of which may be used as needed. Figure 17 thus illustrates, in a broad sense, how individual system elements may be implemented in a relatively separate or relatively more integrated manner.

[0220] The computer system 1700 is shown to include hardware elements that can be electrically coupled via a bus 1705, or communicate otherwise as needed. The hardware elements may include one or more processors 1710, including one or more general-purpose processors and / or one or more special-purpose processors, such as a digital signal processing chip, a graphics accelerator, and / or equivalent; one or more input devices 1715, which may include, but not limited to, a mouse, a keyboard, a camera, and / or equivalent; and one or more output devices 1720, which may include, but not limited to, a display device, a printer, and / or equivalent.

[0221] The computer system 1700 further includes and / or communicates with one or more non-transient storage devices 1725, which may include, but are not limited to, local and / or network-accessible storage devices and / or solid-state storage devices such as disk drives, drive arrays, optical storage devices, random access memory ("RAM"), and / or read-only memory ("ROM"), which may be programmable, flash-updatable, and / or equivalent. Such storage devices may be configured to implement any suitable data storage, including, but are not limited to, various file systems, database structures, and / or equivalents.

[0222] The computer system 1700 may also include a communication subsystem 1719, which may include, but is not limited to, modems, network cards (wireless or wired), infrared communication devices, wireless communication devices, and / or chipsets, such as Bluetooth® devices, 802.11 devices, WiFi devices, WiMAX devices, cellular communication equipment, etc. The communication subsystem 1719 may include one or more input and / or output communication interfaces that enable data to be exchanged with a network, such as a network of other computer systems, televisions, and / or any other devices described herein, as described below to give as an embodiment. Depending on the desired functionality and / or other implementation concerns, a portable electronic device or similar device may communicate images and / or other information via the communication subsystem 1719. In other embodiments, a portable electronic device, e.g., the first electronic device, may be incorporated into the computer system 1700, e.g., the electronic device, as an input device 1715. In some embodiments, the computer system 1700 may further include a working memory 1735, which may include a RAM or ROM device as described above.

[0223] The computer system 1700 may also include computer programs provided by various embodiments and / or may be designed to implement and / or configure the system, including one or more application programs 1745, an operating system 1740, device drivers, executable libraries, and / or other code, as indicated by the working memory 1735. Simply as an example, one or more procedures described with respect to the methods discussed above may be implemented as code and / or instructions executable by a computer or a processor in a computer, and in some respects such code and / or instructions may then be used to configure and / or adapt a general-purpose computer or other device to perform one or more operations in accordance with the methods described.

[0224] These instructions and / or sets of code may be stored on a non-transient computer-readable storage medium such as the storage device 1725 described above. In some cases, the storage medium may be incorporated into a computer system such as computer system 1700. In other embodiments, the storage medium is a removable medium separate from the computer system, such as a compact disk, and / or the storage medium may be provided in an installation package so that it can be used to program, configure, and / or adapt a general-purpose computer with the instructions / code stored thereon. These instructions may take the form of executable code that is executable by computer system 1700, and / or take the form of source and / or installable code that then takes the form of executable code, depending on compilation and / or installation on computer system 1700 using, for example, one of the various generally available compilers, installation programs, compression / decompression utilities, etc.

[0225] It will be apparent to those skilled in the art that substantial variations may be configured according to specific requirements. For example, customized hardware may also be used, and / or certain elements may be implemented in hardware, software including portable software such as applets, or both. Furthermore, connections to other computing devices, such as network input / output devices, may also be employed.

[0226] As described above, in one aspect, some embodiments may employ a computer system such as computer system 1700 to carry out the methods according to various embodiments of the Art. According to one embodiment, some or all of the procedures of such a method are carried out by computer system 1700 in response to processor 1710 executing one or more sequences of one or more instructions, and / or other code such as application program 1745, contained in working memory 1735. Such instructions may be read into working memory 1735 from another computer-readable medium, such as one or more of the storage devices 1725. Simply as an example, the execution of a sequence of instructions contained in working memory 1735 may cause processor 1710 to carry out one or more procedures of the methods described herein. In addition, or alternatively, some of the methods described herein may be carried out through special hardware.

[0227] The terms “machine-readable medium” and “computer-readable medium,” as used herein, refer to any medium involved in providing data that causes a machine to operate in a specific manner. In some embodiments implemented using computer system 1700, various computer-readable media may be involved in providing instructions / code for execution to processor 1710 and / or may be used to store and / or transport such instructions / code. In many implementations, computer-readable media are physical and / or tangible storage media. Such media may take the form of non-volatile or volatile media. Non-volatile media include, for example, optical and / or magnetic disks such as storage device 1725. Volatile media include, but are not limited to, dynamic memory such as working memory 1735.

[0228] Physical and / or tangible computer-readable media in general forms include, for example, floppy disks, flexible disks, hard disks, magnetic tapes, or any other magnetic media, CD-ROMs, any other optical media, punch cards, paper tapes, any other physical media with perforation patterns, RAM, PROMs, EPROMs, FLASH®-EPROMs, any other memory chips or cartridges, or any other media from which a computer can read instructions and / or code.

[0229] Various forms of computer-readable media may be involved in transporting one or more sequences of one or more instructions for execution to the processor 1710. For example, the instructions may first be transported on a magnetic disk and / or optical disk of a remote computer. The remote computer may load the instructions into its dynamic memory and transmit the instructions as signals via a transmission medium that is received and / or executed by the computer system 1700.

[0230] The communication subsystem 1719 and / or its components generally receive signals, and the bus 1705 can then transport the signals and / or the data, instructions, etc. carried by the signals to the working memory 1735, from which the processor 1710 reads and executes the instructions. Instructions received by the working memory 1735 may optionally be stored on the non-transient storage device 1725 either before or after execution by the processor 1710.

[0231] The methods, systems, and devices discussed above are embodiments. Various configurations may omit, substitute, or add various procedures or components as needed. For example, in alternative configurations, the method may be carried out in a different order than described, and / or various steps may be added, omitted, and / or combined. Also, features described in relation to one configuration may be combined in various other configurations. Different aspects and elements of a configuration may be combined in a similar manner. Furthermore, technology is evolving, and therefore many of the elements are embodiments and do not limit the scope or claims of this disclosure.

[0232] Specific details are given in the description to provide a complete understanding of the exemplary configurations, including their implementation. However, the configurations may be practiced without these specific details. For example, well-known circuits, processes, algorithms, structures, and techniques are shown without unnecessary details to avoid obscuring the configurations. This description provides only exemplary configurations and does not limit the scope, availability, or configurations of the claims. Rather, the foregoing description of configurations will provide a useful description for implementing the techniques described to those skilled in the art. Various modifications may be made to the function and arrangement of the elements without departing from the spirit or scope of this disclosure.

[0233] Furthermore, the configuration may be described as a process, depicted as a schematic flowchart or block diagram. Each may be described as a sequential process, although many operations may be performed in parallel or simultaneously. In addition, the order of operations may be rearranged. The process may have additional steps not included in the diagram. Moreover, embodiments of this method may be implemented in hardware, software, firmware, middleware, microcode, hardware description language, or any combination thereof. When implemented in software, firmware, middleware, or microcode, the program code or code segments for performing the required tasks may be stored in a non-transient computer-readable medium such as a storage medium. The processor may perform the described tasks.

[0234] While several exemplary configurations have been described, various modifications, alternative structures, and equivalents may be used without departing from the spirit of this disclosure. For example, the elements described herein may be components of a larger system, and other rules may take precedence over or modify them in a different way for the use of the art. Also, some steps may be taken before, during, or after the elements described herein are considered. Therefore, the foregoing description is not intended to restrict the scope of the claims.

[0235] As used herein and in the appended claims, the singular forms “a,” “an,” and “the” include plural references unless the context clearly indicates otherwise. Thus, for example, a reference to “user” includes multiple such users, and a reference to “processor” includes one or more processors and their equivalents known to those skilled in the art.

[0236] Furthermore, the words “comprise,” “comprising,” “contains,” “containing,” “include,” “including,” and “includes,” when used herein and in the following claims, are intended to specify the presence of the described feature, integer, component, or step, but they do not preclude the presence or addition of one or more other features, integers, components, steps, actions, or groups.

[0237] Furthermore, the examples and embodiments described herein are for illustrative purposes only, and it should be understood that various modifications or changes in light thereof are suggested to those skilled in the art and fall within the spirit, authority, and scope of the appended claims. The present invention provides, for example, the following: (Item 1) A method for operating an optical system, wherein the method is Receiving light associated with a world object, The light associated with the aforementioned world object is to be linearly polarized along the first axis, When the optical system is operating according to the first state, Rotating the polarization of light associated with the aforementioned world object, The light associated with the aforementioned world object is linearly polarized along a second axis perpendicular to the first axis, When the optical system is operating according to the second state, Projecting light associated with a virtual image onto the eyepiece, The light associated with the world object and the light associated with the virtual image are to be linearly polarized along the second axis. Methods that include... (Item 2) The method according to item 1, further comprising rotating the polarization of light associated with the virtual image when the optical system is operating according to the second state. (Item 3) The method according to item 1, further comprising applying a zero net refractive force to the light associated with the world object when the optical system is operating according to the first state. (Item 4) The method according to item 1, further comprising applying a non-zero net refractive power to the light associated with the virtual image when the optical system is operating according to the second state. (Item 5) The method according to item 1, further comprising externally coupling light associated with the virtual image when the optical system is operating according to the second state. (Item 6) An optical system, One or more world-side shutter elements, The light associated with the world object is linearly polarized along the first axis, When the optical system is operating according to the first state, it rotates the polarization of the light associated with the world object. One or more world-side shutter elements configured to perform the following: An eyepiece lens coupled to one or more of the world-side shutter elements, A projector, wherein the projector is configured such that when the optical system is operating according to a second state, it projects light associated with a virtual image onto the eyepiece. One or more user-side shutter elements coupled to the eyepiece, When the optical system is operating according to the first state, it linearly polarizes the light associated with the world object along a second axis perpendicular to the first axis. When the optical system is operating according to the second state, it linearly polarizes the light associated with the world object and the light associated with the virtual image along the second axis. One or more user-side shutter elements configured to perform the following: An optical system equipped with [the necessary components]. (Item 7) The aforementioned one or more user-side shutter elements further, The optical system according to item 6, wherein the optical system is configured to rotate the polarization of light associated with the virtual image when the optical system is operating according to the second state. (Item 8) The optical system according to item 6, further comprising a lens assembly coupled to one or more user-side shutter elements. (Item 9) The optical system according to item 8, wherein the lens assembly is configured to apply zero net refractive power to the light associated with the world object when the optical system is operating according to the first state. (Item 10) The optical system according to item 8, wherein the lens assembly is configured to apply a non-zero net refractive power to the light associated with the virtual image when the optical system is operating according to the second state. (Item 11) The optical system according to item 6, wherein the eyepiece is configured to externally couple the light associated with the virtual image toward the one or more user-side shutter elements when the optical system is operating according to the second state. (Item 12) The one or more world-side shutter elements are, World polarizer and World-side switchable waveplate and Includes, The one or more user-side shutter elements are: User-side polarizer, User-switchable waveplate and Optical systems as described in item 6, including the optical systems described in item 6. (Item 13) The optical system according to item 12, wherein the optical system operates according to the first state when the world-side switchable waveplate is electrically activated and the user-side switchable waveplate is not electrically activated. (Item 14) The optical system according to item 12, wherein the optical system operates according to the second state when the user-side switchable waveplate is electrically activated and the world-side switchable waveplate is not electrically activated. (Item 15) The optical system according to item 12, wherein the global polarizer is coupled to the global switchable waveplate. (Item 16) An optical system, A projector configured to emit light, At least one waveguide optically coupled to the projector, wherein the at least one waveguide is configured to receive light and redirect it toward the user, A shutter assembly comprising at least one component positioned adjacent to the at least one waveguide, wherein the shutter assembly is selectively switchable between different states, each configured to allow different amounts of ambient light from the user's environment to pass through it toward the user. An adaptive lens assembly positioned between the at least one waveguide and the user, wherein the adaptive lens assembly is selectively switchable between different states, each of which the adaptive lens is configured to impart different amounts of wavefront divergence to the light passing through it toward the user. A control network communicatively coupled to the projector, the shutter assembly, and the adaptive lens assembly, wherein the control network is configured to synchronously switch the shutter assembly and the adaptive lens assembly between two or more states at a specific rate, and the two or more states are A first state in which the shutter assembly is configured to allow a first amount of ambient light from the user's environment to pass through it toward the user, and the adaptive lens assembly is configured to impart a first amount of wavefront divergence to the light passing through it, In the second state, the shutter assembly is configured to allow a second amount of ambient light from the user's environment to pass through it toward the user, and the adaptive lens assembly is configured to impart a second amount of wavefront divergence to the light passing through it, wherein the second amount of ambient light is different from the first amount of ambient light, and the second amount of wavefront divergence is different from the first amount of wavefront divergence. A control network including, An optical system equipped with [the necessary components]. (Item 17) The optical system according to item 16, wherein the second amount of ambient light is less than the first amount of ambient light, and the wavefront divergence of the second amount is greater than the wavefront divergence of the first amount. (Item 18) The optical system according to item 16, wherein the specific rate at which the shutter assembly and the adaptive lens assembly are synchronously switched between the two or more states includes a rate equal to or greater than the minimum switching frequency. (Item 19) The optical system according to item 16, wherein in the second state, the control circuit network is configured to cause the projector to emit light representing virtual content that will be perceived by the user as being located at a first depth in front of the user, and the control circuit network is configured to determine at least one of the second amount of ambient light and the second amount of wavefront divergence based on the first depth in front of the user that the virtual content will be perceived by the user. (Item 20) The optical system according to item 16, wherein at least one component of the shutter assembly comprises at least one component positioned between the at least one waveguide and the user.

Claims

1. An optical system, A projector configured to emit light, At least one waveguide optically coupled to the projector, wherein the at least one waveguide is configured to receive light and redirect it toward the user, A shutter assembly comprising at least one component positioned adjacent to the at least one waveguide, wherein the shutter assembly is selectively switchable between different states such that the shutter assembly is configured to allow different amounts of ambient light from the user's environment to pass through it toward the user, and the at least one component of the shutter assembly comprises at least one component positioned between the at least one waveguide and the user, An adaptive lens assembly positioned between the at least one waveguide and the user, wherein the adaptive lens assembly is selectively switchable between different states, each configured to impart a different amount of wavefront divergence to the light passing through it toward the user; A control circuit network is communicatively coupled to the projector, the shutter assembly, and the adaptive lens assembly, wherein the control circuit network is configured to synchronously switch the shutter assembly and the adaptive lens assembly between two or more states at a specific rate, and the two or more states are A first state in which the shutter assembly is configured to allow a first amount of ambient light from the user's environment to pass through it toward the user, and the adaptive lens assembly is configured to impart a first amount of wavefront divergence to the light passing through it, In the second state, the shutter assembly is configured to allow a second amount of ambient light from the user's environment to pass through it toward the user, and the adaptive lens assembly is configured to impart a second amount of wavefront divergence to the light passing through it, wherein the second amount of ambient light is different from the first amount of ambient light, and the second amount of wavefront divergence is different from the first amount of wavefront divergence. A control network including, An optical system equipped with [the necessary components].

2. The optical system according to claim 1, wherein the second amount of ambient light is less than the first amount of ambient light, and the wavefront divergence of the second amount is greater than the wavefront divergence of the first amount.

3. The optical system according to claim 1, wherein the specific rate at which the shutter assembly and the adaptive lens assembly are synchronously switched between the two or more states includes a rate equal to or greater than the minimum switching frequency.

4. The optical system according to claim 1, wherein in the second state, the control circuit network is configured to cause the projector to emit light representing virtual content that will be perceived by the user as being positioned at a first depth in front of the user, and the control circuit network is configured to determine at least one of a second amount of ambient light and a second amount of wavefront divergence based on the first depth in front of the user at which the virtual content will be perceived by the user.

5. The optical system according to claim 1, wherein the optical system is an augmented reality (AR) device.

6. The optical system according to claim 1, wherein the at least one waveguide includes a plurality of waveguides that form an eyepiece of the optical system.

7. A method for operating an optical system, In a projector, emitting light and The projector is optically coupled to at least one waveguide, from which light is received and redirected toward the user. A shutter assembly comprising at least one component positioned adjacent to the at least one waveguide, wherein the shutter assembly selectively switches between different states, each allowing different amounts of ambient light from the user's environment to pass through it toward the user, wherein at least one component of the shutter assembly comprises at least one component positioned between the at least one waveguide and the user. An adaptive lens assembly positioned between the at least one waveguide and the user is configured to selectively switch between different states, each of which imparts a different amount of wavefront divergence to the light passing through it toward the user. A control circuit network is used to synchronously switch between two or more states at a specific rate, wherein the two or more states are: A first state in which the shutter assembly is configured to allow a first amount of ambient light from the user's environment to pass through it toward the user, and the adaptive lens assembly is configured to impart a first amount of wavefront divergence to the light passing through it, A second state includes a second state in which the shutter assembly is configured to allow a second amount of ambient light from the user's environment to pass through it toward the user, and the adaptive lens assembly is configured to impart a second amount of wavefront divergence to the light passing through it, wherein the second amount of ambient light is different from the first amount of ambient light, and the second amount of wavefront divergence is different from the first amount of wavefront divergence. Methods that include...

8. The method according to claim 7, wherein the second amount of ambient light is less than the first amount of ambient light, and the wavefront divergence of the second amount is greater than the wavefront divergence of the first amount.

9. The method according to claim 7, wherein the specific rate at which the shutter assembly and the adaptive lens assembly are switched synchronously between the two or more states includes a rate equal to or greater than the minimum switching frequency.

10. The method according to claim 7, wherein in the second state, the control circuit network causes the projector to emit light representing virtual content that will be perceived by the user as being positioned at a first depth in front of the user, and the control circuit network determines at least one of the second amount of ambient light and the second amount of wavefront divergence based on the first depth in front of the user at which the virtual content will be perceived by the user.

11. The method according to claim 7, wherein the optical system is an augmented reality (AR) device.

12. The method according to claim 7, wherein the at least one waveguide includes a plurality of waveguides that form the eyepiece of the optical system.

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